Composite film based on propylene polymers, process for its preparation and use

Abstract

This invention discloses a propylene polymer-based composite film, its preparation method, and its applications. The composite film comprises at least two distinct layers: layer a and layer b; wherein layer a and layer b each contain at least one propylene polymer; and at least one of layers a and b contains a propylene impact copolymer; wherein the propylene impact copolymer contains an elastic portion that forms a dispersed, strip-shaped rubber phase in the composite film, the rubber phases being arranged parallel to each other, and the average dimension of the rubber phases along their transverse axis being 20-200 nm and the average aspect ratio being 5-20. This composite film simultaneously exhibits excellent impact resistance and optical properties, even good tensile properties and / or good heat-sealing strength at relatively low heat-sealing temperatures, and even good uniformity. This composite film is particularly suitable for use in the packaging materials field, especially in battery packaging materials, electronic product packaging materials, or food packaging materials.

Description

Technical Field

[0001] This invention relates to the field of polymer films, and more specifically to composite films based on propylene polymers, methods for their preparation and applications, as well as packaging materials comprising said composite films. Background Technology

[0002] Polypropylene films are typically produced by methods such as casting and biaxial stretching, but polypropylene films made from homopolymer polypropylene raw materials usually have low impact strength. Since polypropylene films are commonly used in packaging, they require high impact resistance, and good optical properties are also desirable for visibility and aesthetic appeal of the contents.

[0003] To improve the impact resistance of polypropylene films, impact-resistant polypropylene can be used to prepare the film, or polyolefin elastomers can be added to the polypropylene. However, films prepared by these methods typically have high haze and poor optical properties such as transparency. Nucleating agents can also be added to the film simultaneously to reduce haze by refining the crystals within the film, but this method leads to a decrease in impact resistance.

[0004] To improve the impact resistance and toughness of films, multilayer co-extrusion can be used to prepare films. For example, CN101913279A uses a three-layer co-extrusion method to prepare composite films. The layers of the film contain elastomers and polypropylene blended in a ratio of 1:10 to 1:3, with the elastomers providing better impact resistance. However, this method suffers from difficulty in uniform dispersion when the elastomer content is high. Moreover, elastomers typically have poor flow properties, leading to uneven film surfaces and significant thickness differences along the machine direction (MD) and transverse direction (TD), making it difficult to obtain films with good optical properties. Furthermore, there are limitations on the amount of elastomer added, as phase separation can occur at higher levels, thus limiting further improvements in impact resistance. In addition, during multilayer co-extrusion, the elastomers can cause significant differences in flow properties between the core and surface layers, further exacerbating the unevenness of the film surface and potentially leading to inhomogeneity in the film's properties. Differences in the rheological properties of the raw materials between layers also affect the film's uniformity and consequently its optical and mechanical properties.

[0005] Existing propylene polymer-based films struggle to simultaneously possess both good optical and impact resistance. Furthermore, when used in packaging applications, propylene polymer films typically require good heat-sealing performance at relatively low temperatures, a requirement that current technologies fail to meet. Additionally, existing composite films exhibit poor uniformity in thickness and performance. Summary of the Invention Invention Overview

[0007] In view of the prior art as described above, the object of the present invention is to provide a low-haze, high-impact film based on propylene polymers and a method for preparing the same. Such a film can simultaneously possess excellent impact resistance and optical properties.

[0008] Another object of the present invention is to provide the above-described film, which may additionally have excellent mechanical properties (e.g., tensile properties) and / or excellent heat-sealing strength at a lower heat-sealing temperature.

[0009] Another object of the present invention is to provide a transparent impact-resistant composite film based on propylene polymer, which has good impact resistance and optical properties, as well as good uniformity of film thickness and properties.

[0010] Another object of the present invention is to provide a method for preparing the composite film, wherein the preparation process is stable and the resulting film has good uniformity.

[0011] According to the present invention, the objective is achieved by using a propylene impact copolymer containing a specific elastic portion as a raw material in at least one layer of the composite film, and preparing a composite film containing a specific microstructure with a uniformly dispersed strip-shaped rubber phase by extrusion casting.

[0012] Therefore, a first aspect of the present invention provides a composite film based on a propylene polymer, comprising at least two different layers: layer a and layer b;

[0013] Layer a and layer b each comprise at least one propylene polymer; and

[0014] At least one of layers a and b comprises a propylene impact copolymer;

[0015] The propylene impact copolymer contains an elastic portion that forms a dispersed, strip-shaped rubber phase in the composite film.

[0016] A second aspect of the present invention provides a method for preparing the composite film of the present invention, comprising extruding and casting a raw material composition for forming each layer to form the composite film.

[0017] A third aspect of the present invention provides the application of the composite film of the present invention in the field of packaging materials.

[0018] A fourth aspect of the present invention provides packaging materials comprising the composite film of the present invention.

[0019] Other aspects and advantages of the invention will become clear from the following detailed description and specific embodiments of the invention, taken in conjunction with the accompanying drawings. Attached Figure Description

[0020] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0021] Figure 1a and Figure 1b This is a schematic diagram illustrating the selection of sampling points for the thin film in this invention.

[0022] Figure 2 This is a scanning electron microscope (SEM) image of a cross-section of a propylene impact copolymer sample used in Example A1 of the present invention.

[0023] Figure 3 An atomic force microscope image of a cross-section of a thin film according to Embodiment A1 of the present invention.

[0024] Figure 4 The image shown is an atomic force microscope photograph of a cross-section of a thin film, which is not based on Comparative Example A3 of the present invention.

[0025] Figure 5 An atomic force microscope image of a cross-section of a thin film according to embodiment C1 of the present invention.

[0026] Figure 6a This is a SEM image of the cross-section of a propylene impact copolymer sample used in Example E1 of the present invention.

[0027] Figure 6b The image shows a cross-section of a propylene impact copolymer sample that was not used in Comparative Example E1 according to the present invention.

[0028] Figure 7 An atomic force microscope image of a cross-section of a thin film according to Embodiment E1 of the present invention. Invention Details

[0030] A first aspect of the present invention provides a composite film based on a propylene polymer, comprising at least two different layers: layer a and layer b;

[0031] Layer a and layer b each comprise at least one propylene polymer; and

[0032] At least one of layers a and b comprises a propylene impact copolymer;

[0033] The propylene impact copolymer contains an elastic portion that forms a dispersed, strip-shaped rubber phase in the composite film.

[0034] The term "dispersion" in this article refers to the non-continuous distribution of the rubber phase in the composite film. The rubber phase can be observed by examining a transverse (TD) section of the composite film using atomic force microscopy (AFM). Figure 3 , 5 As shown in the black portion of Figure 7, the rubber phase is uniformly dispersed in the film matrix in the form of multiple strips.

[0035] In this article, "strip-shaped" refers to a shape with an aspect ratio that is usually greater than 2.

[0036] In this article, aspect ratio refers to the ratio of the vertical axis to the horizontal axis of an object. The vertical axis refers to the longest dimension of the object (in this case, the rubber phase), that is, the distance between the two points furthest apart on the object's outline. The horizontal axis refers to the length between the points of intersection of the vertical axis and the object's outline.

[0037] In the composite film of the present invention, the average dimension of the horizontal axis of the rubber phase can be 20-200 nm, more preferably 20-150 nm. The average aspect ratio of the rubber phase can be 5-20, preferably 5-15.

[0038] The transverse dimension and aspect ratio were measured by observing the cross-section of the composite film cut along the transverse direction (TD) using an atomic force microscope. Based on 200 sample points, the average transverse dimension of the rubber phase was calculated as the average transverse dimension of the rubber phase, and the average aspect ratio of the rubber phase was calculated as the average aspect ratio of the rubber phase.

[0039] Longitudinal (MD) refers to the machining direction. Lateral (TD) refers to the direction perpendicular to the machining direction.

[0040] In the composite film of the present invention, the rubber phases are advantageously arranged in parallel to each other.

[0041] In this paper, the term "parallel arrangement" refers to the arrangement of the transverse cross-sections of the rubber phase parallel to each other along a certain direction. This excludes a small number of rubber phase particles located in local areas with different orientations due to the preparation process, which are inconsistent with the overall orientation of the rubber phase particles in the entire composite film, as well as rubber phase particles that cannot be clearly observed due to the preparation process or AFM method.

[0042] In this article, "parallel arrangement" includes cases where they are substantially parallel. The angle between the transverse sections of the rubber phases is no greater than about 10 degrees, and preferably less than about 5 degrees.

[0043] In this invention, layers a and b both contain at least one propylene polymer and are composed of propylene polymer-based compositions, but their specific compositions and / or thicknesses differ. The entire composite film is a propylene polymer-based composite film, and can also be referred to as a polypropylene composite film.

[0044] In this invention, layer a is intended to be used as the core layer of the composite film, that is, a layer that is relatively far from the medium that the composite film will contact during use. Layer b is intended to be used as the surface layer of the composite film, that is, a layer that is close to the medium that the composite film will contact during use, such as the electrolyte that the battery packaging material contacts.

[0045] According to the present invention, at least one of layers a and b comprises the propylene impact copolymer having a specific elastic portion, thereby enabling the entire composite film to contain a specifically dispersed rubber phase.

[0046] The elastic portion can be observed as a spherical or near-spherical rubber phase in scanning electron microscope images of impact specimens of propylene impact copolymers.

[0047] The propylene impact copolymer is preferably a propylene impact copolymer containing ethylene units, wherein the elastic portion is a copolymer containing ethylene units, preferably selected from ethylene-propylene copolymer and ethylene-butene copolymer.

[0048] Preferably, the propylene impact copolymer comprises a homopolymer portion of propylene and a copolymer portion containing ethylene units. The homopolymer portion of propylene may contain an isotactic polymer structure.

[0049] The copolymer containing ethylene units in the propylene impact copolymer is preferably 3-15% by weight, more preferably 7-12% by weight. 13 C NMR determination.

[0050] Based on the total weight of the propylene impact copolymer, the ethylene unit content of the propylene impact copolymer is preferably 1-14% by weight, more preferably 3-12% by weight. In the room-temperature xylene-soluble portion of the propylene impact copolymer, the ethylene unit content is preferably no more than 40% by weight. The ethylene unit group [EEE] content is preferably no more than 20% by weight, through… 13 C NMR determination.

[0051] The propylene impact copolymer may have a block structure or contain propylene block copolymers.

[0052] The melt mass flow rate (MFR) of the propylene impact copolymer at 230°C and 2.16 kg load can be 1-10 g / 10 min, preferably 1-8 g / 10 min, and is determined according to standard GB / T3682-2000, with a test temperature of 230°C and a load of 2.16 kg.

[0053] Available propylene impact copolymers are commercially available, such as propylene impact copolymer EP200K from Sinopec, propylene impact copolymers F200R and M180R from Shanghai Petrochemical, propylene impact copolymer PPB-M02D from Maoming Petrochemical, and propylene impact copolymer J410F from Hyosung, South Korea.

[0054] The propylene impact copolymer can also be prepared by continuous polymerization in the presence of a Ziegler-Natta catalyst with high stereoselectivity. The continuous polymerization method refers to a preparation process comprising at least two sequential steps, wherein the elastic and inelastic portions are each prepared in separate steps, and, except for the first step, the subsequent step is carried out in the presence of the polymer formed in the previous step and the catalyst used in the previous step.

[0055] Layer a may comprise homopolymer polypropylene and / or random copolymers of propylene.

[0056] The preferred melt flow rate of the homopolymer polypropylene at 230℃ and 2.16kg load is 2-15 g / 10min, determined according to standard GB / T 3682-2000, with a test temperature of 230℃ and a load of 2.16kg. The isotacticity of the homopolymer polypropylene is preferably greater than 97%, as determined by… 13 C NMR determination. The molecular weight distribution (Mw / Mn) of the homopolymer polypropylene is preferably 4.5-7.0, determined by gel permeation chromatography (GPC). Commercially available homopolymer polypropylene is available, for example, PPH-FA03 from Qingdao Refining & Chemical, PPH-FA03 from Zhongyuan Petrochemical, and FC801 from Shanghai Petrochemical; or it can be prepared by conventional methods in the art.

[0057] The propylene random copolymer can be a copolymer of propylene with ethylene and / or butene, such as an ethylene-propylene-butene ternary random copolymer, a propylene-ethylene binary random copolymer, or a propylene-butene binary random copolymer. The melt flow rate of the propylene random copolymer at 230°C and a load of 2.16 kg can be 2-15 g / 10 min, preferably 2-10 g / 10 min, as determined according to standard GB / T3682-2000. The molecular weight distribution (Mw / Mn) of the random copolymer is preferably 4.5-7.0, determined by GPC. Commercially available propylene random polymers are available, for example, the random propylene copolymer of Yanshan Petrochemical (brand name F5006), or the random propylene copolymer of Shanghai Petrochemical (brand names F500EPS, F800EDF, or F800EPS); or they can be prepared by conventional methods in the art.

[0058] Layer b may contain a propylene random copolymer. The propylene random copolymer is as described above. Layer b may be the same as or different from the propylene random copolymer in layer a. For example, layer b may contain 60-100% by weight of the propylene random copolymer.

[0059] In a preferred embodiment, at least one of layers a and b may contain a polyolefin elastomer, thereby advantageously further improving the impact resistance of the composite film.

[0060] The polyolefin elastomer can be an elastomer copolymer of ethylene and α-olefin. The α-olefin is preferably C3-C. 12 The α-olefin is more preferably selected from at least one of propylene, 1-butene, 1-hexene, and 1-octene. Available polyolefin elastomers are commercially available, for example, Dow's polyolefin elastomer 8200, Dow's polyolefin elastomer 8411, Mitsui's polyolefin elastomers DF640 or DF840, Exxon's polyolefin elastomers 6102, VM3980, or EXACT3139; or can be prepared by methods conventional in the art.

[0061] When a polyolefin elastomer is used in the composite film, the elastic portion of the propylene impact copolymer and the polyolefin elastomer form a dispersed rubber phase in the composite film. This rubber phase also takes the form of strips and is arranged parallel to each other. The average dimension of the transverse axis of such a rubber phase can be 20-200 nm, preferably 20-150 nm. The average aspect ratio of this rubber phase can be 5-20, preferably 5-15. The dimensions are determined by AFM as described above.

[0062] The presence of polyolefin elastomers can advantageously compensate for the potential uneven distribution of the rubber phase in propylene impact copolymers, thereby improving the uniformity of impact properties throughout the film.

[0063] In a preferred embodiment, the polyolefin elastomer has a temperature of 230°C and a shear rate of 160 s. -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 1.2-3, preferably 1.7-2.3. The polyolefin elastomer is subjected to a shear rate of 640 s at 230°C. -1 The shear viscosity η 640 Preferably 100-500 Pa·s, more preferably 140-400 Pa·s. Shear viscosity η 160 and η 640 The measurements were performed using a capillary rheometer according to ISO 11443:2014.

[0064] The melt flow rate of the material constituting layer a (propylene polymer composition) at 230°C and under a load of 2.16 kg can be 2-10 g / 10 min, preferably 2-8 g / 10 min, more preferably 3-7 g / 10 min, as determined according to standard GB / T3682-2000, with a test temperature of 230°C and a load of 2.16 kg.

[0065] The melt flow rate of the material constituting layer b (propylene polymer composition) at 230°C and under a load of 2.16 kg can be 2-10 g / 10 min, preferably 3-10 g / 10 min, more preferably 3-9 g / 10 min, and even more preferably 4-8 g / 10 min, as determined according to standard GB / T 3682-2000, with a test temperature of 230°C and a load of 2.16 kg.

[0066] Such a melt mass flow rate can advantageously make the thin film preparation process more stable, thereby giving the thin film better uniformity, mechanical properties and optical properties.

[0067] Layer a and layer b may both contain the propylene impact copolymer, wherein the propylene impact copolymer in layers a and b may be the same or different. Alternatively, only one of layers a and b may contain the propylene impact copolymer.

[0068] Layers a and b may both contain the polyolefin elastomer, wherein the polyolefin elastomers in layers a and b may be the same or different. Preferably, the weight ratio of the polyolefin elastomer in layer a to the weight ratio of the polyolefin elastomer in layer b is 6:1 to 1:6. Alternatively, only one of layers a and b may contain the polyolefin elastomer.

[0069] Layer a and layer b may both contain the propylene impact copolymer and the polyolefin elastomer, wherein the propylene impact copolymer in layer a and layer b may be the same or different, and the polyolefin elastomer in layer a and layer b may be the same or different.

[0070] It is also possible that only one of layers a and b contains the propylene impact copolymer, and one or both of layers a and b contain the polyolefin elastomer; or, only one of layers a and b contains the polyolefin elastomer, and one or both of layers a and b contain the propylene impact copolymer.

[0071] In one embodiment, layer a comprises the homopolymer polypropylene, the propylene impact copolymer, and the polyolefin elastomer, and layer b comprises the random propylene copolymer and the polyolefin elastomer.

[0072] In this embodiment, preferably, the weight ratio of the polyolefin elastomer in layer a to the weight ratio of the polyolefin elastomer in layer b is 2:1 to 1:4, for example, it can be 1.5:1, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, and any value between them, more preferably 1:1 to 1:2. When co-extruded bilayer or multilayer films, the aforementioned weight ratio of the polyolefin elastomer in layer a to the weight ratio of the polyolefin elastomer in layer b can further improve the impact resistance and optical properties of the composite film, while also making the extrusion process more stable.

[0073] Specifically, in this embodiment, layer a may comprise 40-90 wt%, preferably 50-90 wt%, more preferably 55-75 wt% of the homopolymer polypropylene, 5-40 wt%, preferably 10-30 wt% of the propylene impact copolymer, and 2-30 wt%, preferably 5-20 wt% of the polyolefin elastomer, each based on the total weight of layer a. Layer b may comprise 40-95 wt%, preferably 60-95 wt%, more preferably 75-90 wt% of the random propylene copolymer, and 5-60 wt%, preferably 5-40 wt%, more preferably 10-25 wt% of the polyolefin elastomer, each based on the total weight of layer b.

[0074] Composite films containing such surface and core layers can advantageously possess not only excellent optical properties but also improved heat-sealing strength.

[0075] In this embodiment, the thickness uniformity and performance uniformity of the film can be greatly improved when the polyolefin elastomers in both layer a and layer b meet the following conditions: at 230°C and a shear rate of 160 s. -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 1.2-3, preferably 1.7-2.3, and is achieved at 230°C and a shear rate of 640 s. -1 The shear viscosity η 640 The value is 100-500 Pa·s, preferably 140-400 Pa·s.

[0076] Furthermore, preferably, the propylene polymer composition used to form layer a and the propylene polymer composition used to form layer b are controlled at 230°C and a shear rate of 160 s. -1 The difference in shear viscosity (ηA) 160 -ηB 160 ) and at 230℃ and a shear rate of 640s -1 The difference in shear viscosity (ηA) 640 -ηB 640Both ) are ≥0, and the ratio of the two (ηA) 160 -ηB 160 ) / (ηA 640 -ηB 640 The ratio is 1-2.6, preferably 1.4-2.5, and more preferably 1.5-2.2. This allows for further improvement in the uniformity of film thickness and performance by adjusting the flowability of each layer of raw materials.

[0077] In another embodiment, layer a comprises a propylene polymer and the polyolefin elastomer, and layer b comprises the random propylene copolymer, the polyolefin elastomer, and the propylene impact copolymer. The propylene polymer in layer a may be selected from homopolymer polypropylene and / or the propylene impact copolymer. For example, layer a may comprise 70-100% by weight of the propylene polymer.

[0078] In this embodiment, preferably, the weight ratio of the polyolefin elastomer in layer a to the weight ratio of the polyolefin elastomer in layer b is 10:1-1:6, more preferably 6:1-1:4, and even more preferably 4:1-1:4. For example, it can be 3.5:1, 3:1, 2.5:1, 2:1, 1.5:1, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, and any value between them. When co-extrudeing bilayer or multilayer films, the aforementioned weight ratio of the polyolefin elastomer in layer a to the weight ratio of the polyolefin elastomer in layer b can further improve the impact resistance and optical properties of the composite film, while also making the extrusion process more stable.

[0079] Specifically, in this embodiment, layer a may comprise 50-95% by weight, preferably 70-95% by weight, more preferably 80-95% by weight, of the propylene polymer and 5-50% by weight, preferably 5-30% by weight, more preferably 5-20% by weight, of the polyolefin elastomer, each based on the total weight of layer a; layer b may comprise 40-90% by weight, preferably 50-90% by weight, more preferably 60-85% by weight, of the random propylene copolymer, 5-40% by weight, preferably 5-30% by weight, more preferably 5-20% by weight, of the polyolefin elastomer and 2-30% by weight, preferably 5-20% by weight, of the propylene impact copolymer, each based on the total weight of layer b.

[0080] Composite films containing such surface and core layers not only have improved impact resistance, optical and mechanical properties, but also, due to the synergistic effect between the propylene impact copolymer containing a specific rubber phase in the surface layer (heat seal layer) and other components, can effectively improve heat seal strength while reducing heat seal temperature.

[0081] In another embodiment, layer a comprises the polyolefin elastomer, the propylene impact copolymer, and other types of propylene polymers, the other types of propylene polymers being selected from the homopolymer polypropylene and / or the random copolymer of propylene; and layer b comprises the random copolymer of propylene and the polyolefin elastomer.

[0082] Specifically, in this embodiment, layer a may comprise 40-90 wt% of propylene impact copolymer, 5-40 wt% of other types of propylene polymer, and 2-30 wt% of polyolefin elastomer, preferably 55-75 wt% of propylene impact copolymer, 10-30 wt% of other types of propylene polymer, and 5-20 wt% of polyolefin elastomer, each based on the total weight of layer a; layer b may comprise 40-95 wt% of propylene random copolymer and 5-60 wt% of polyolefin elastomer, preferably 75-90 wt% of propylene random copolymer and 10-25 wt% of polyolefin elastomer, each based on the total weight of layer b.

[0083] This composite film can simultaneously possess excellent impact resistance, optical properties, and tensile properties, and can also exhibit good heat-sealing strength at relatively low heat-sealing temperatures.

[0084] In this paper, the sum of the weight percentages of all components in each layer is 100% by weight.

[0085] additive

[0086] Layer a and / or layer b may also contain at least one of the additives commonly used in polymer films, such as antioxidants, lubricants, antihalogen agents, light stabilizers, heat stabilizers, colorants, fillers, slip agents, surface adhesives, electromagnetic shielding aids, flame retardants, insulating additives, anti-sticking agents, and antistatic agents.

[0087] For example, antioxidants can be used to improve the oxidation resistance of the composite film during processing. The antioxidant can be at least one of various antioxidants commonly used in the art, such as antioxidant 1076, antioxidant 1010, antioxidant 168, and thioester antioxidants (e.g., DLTP, DSTP). Based on 100 parts by weight of the total weight of the layer, the content of the antioxidant can be 0.1-0.8 parts by weight, preferably 0.2-0.4 parts by weight.

[0088] To improve or impart other properties to the composite film (such as friction, stability, color, antistatic properties, strength, conductivity, insulation, slip, sliding properties, surface adhesion, electromagnetic shielding properties, flame retardancy, anti-blocking effect, etc.), the composite film may also contain other film additives conventionally used in the art, such as at least one selected from lubricants, halogen inhibitors, light stabilizers, heat stabilizers, colorants, fillers, slip agents, surface adhesives, electromagnetic shielding additives, flame retardants, insulating additives, anti-sticking agents, and antistatic agents. These film additives can be used in conventional amounts; for example, based on 100 parts by weight of the total weight of the layer, the content of each of the other film additives can be 0.01-0.5 parts by weight, preferably 0.05-0.3 parts by weight, more preferably 0.05-0.15 parts by weight, unless otherwise explicitly specified.

[0089] For example, a lubricant can be added to the composite film. The lubricant can be a PEG-based lubricant and / or a monoglyceride lubricant. Based on 100 parts by weight of the total weight of the layer, the lubricant content can be 0.01-0.5 parts by weight, preferably 0.05-0.2 parts by weight.

[0090] The composite film of the present invention can be modified with polar monomers as a surface adhesive, thereby enhancing the adhesion between the composite film and other materials, resulting in a highly adhesive and impact-resistant propylene polymer composite film. The modified polar monomers are particularly added to layer b.

[0091] In a preferred embodiment, based on the total weight of layer a, layer a may contain 40-90 wt%, preferably 50-85 wt%, of homopolymer polypropylene, 5-45 wt%, preferably 10-30 wt%, of propylene impact copolymer, and 2-40 wt%, preferably 5-20 wt%, of polyolefin elastomer; and based on the total weight of layer b, layer b may contain 40-99 wt%, preferably 70-90 wt%, of propylene random copolymer, 0-30 wt%, preferably 5-15 wt%, of polyolefin elastomer, and 1-30 wt%, preferably 5-15 wt%, of polar monomer modified polypropylene.

[0092] In another preferred embodiment, based on the total weight of layer a, layer a may contain 50-100 wt%, preferably 75-95 wt%, of polypropylene and 0-50 wt%, preferably 5-25 wt%, of polyolefin elastomer; and based on the total weight of layer b, layer b may contain 30-90 wt%, preferably 60-85 wt%, of propylene random copolymer, 5-40 wt%, preferably 5-20 wt%, of polyolefin elastomer, 2.5-20 wt%, preferably 5-10 wt%, of propylene impact copolymer and 2.5-20 wt%, preferably 5-10 wt%, of polar monomer modified polypropylene.

[0093] The polar monomer in the polar monomer-modified polypropylene can be selected from at least one of hydroxyl-containing comonomers, cyano-containing comonomers, and acid anhydride monomers. The hydroxyl-containing comonomer is preferably a hydroxy acid and / or vinyl alcohol. The cyano-containing comonomer is preferably cyanoacrylate. The acid anhydride monomer is preferably maleic anhydride and / or itaconic anhydride, more preferably maleic anhydride. Maleic anhydride-grafted polypropylene (PP-g-MAH) possesses both polar groups and non-polar olefin segments, retaining the basic physical properties of original polypropylene, such as high crystallinity, high strength, and high impact resistance, and exhibiting improved adhesion to other materials.

[0094] The polar monomer-modified polypropylene is commercially available, for example, maleic anhydride-modified polypropylene of Mitsui Chemicals Co., Ltd. with the brand name QF551A, maleic anhydride-modified polypropylene of Jia Yi Rong Co., Ltd. with the brand name CMG9801, and maleic anhydride-modified polypropylene of ExxonMobil Co., Ltd. with the brand name PO1015.

[0095] Conductive fillers can also be added to the composite film of the present invention to improve its antistatic properties. The conductive filler is preferably added to layer b. Based on 100 parts by weight of the matrix polymer in layer b, the amount of conductive filler added can be 0.1-10 parts by weight, preferably 0.5-4.5 parts by weight.

[0096] The conductive filler can be, for example, at least one of carbon black, graphite, carbon nanotubes, carbon fibers, conductive metal particles, conductive metal fibers, and metal oxides. The carbon black conductive filler includes, but is not limited to, at least one of acetylene black, superconducting carbon black, and highly conductive carbon black. The graphite conductive filler includes, but is not limited to, at least one of natural graphite, expandable graphite, expanded graphite, and graphene. The carbon nanotube conductive filler includes, but is not limited to, unmodified or surface-modified single-walled carbon nanotubes and / or multi-walled carbon nanotubes. The conductive metal in the conductive metal particles and conductive metal fibers can each independently be at least one of silver, aluminum, copper, iron, nickel, and stainless steel. The filler coated with conductive metal can be selected from at least one of lead-plated, nickel-plated, silver-plated glass spheres, glass fibers, and mica sheets. The metal oxide includes, but is not limited to, at least one of titanium oxide, zinc oxide, tin oxide, indium oxide, and cadmium oxide. An antistatic propylene polymer film with a surface resistivity of 10⁻⁶ can be prepared by adding conductive fillers. 2 -10 8 Ω, preferably 10 2 -10 4 The electrostatic discharge (ESD) was measured using a Keithley 6517B Electrometer. The film exhibits durable antistatic properties and is minimally affected by ambient humidity.

[0097] Alternatively, an electromagnetic shielding agent can be added to the composite film to prepare an electromagnetic shielding film. The electromagnetic shielding agent is preferably added to layer b. The electromagnetic shielding agent can be a conductive metal filler and / or a carbon material. The conductive metal filler is preferably conductive metal particles and / or conductive metal fibers. The metals in the conductive metal particles and conductive metal fibers can be independently selected from one or more of silver, aluminum, copper, iron, nickel, and stainless steel. The carbon material is preferably one or more of carbon black, graphite, graphene, and carbon nanotubes. The amount of electromagnetic shielding agent added can be 5-30 parts by weight, preferably 15-25 parts by weight, based on 100 parts by weight of the matrix polymer in layer b. The resulting composite film can achieve an electromagnetic shielding effectiveness of ≥25dB, preferably ≥28dB, tested using a flange coaxial testing device according to SJ20524 standard, with an electromagnetic wave band from 50MHz to 1GHz.

[0098] The electromagnetic shielding aid can also be used in combination with a coupling agent. The coupling agent improves the compatibility between the matrix polymer component (resin component) of the propylene polymer composition and the electromagnetic shielding aid. Its type, usage, and dosage can be conventionally selected in the art. For example, the coupling agent can be selected from titanate coupling agents, specifically one or more of monoalkoxy titanates, monoalkyl pyrophosphate titanates, coordination titanates, and chelate titanates. Preferably, the titanate coupling agent is selected from tetrabutyl titanate and / or tetraisopropyl titanate. Based on 100 parts by weight of the total weight of the matrix polymer component, the content of the coupling agent can be 1-6 parts by weight, preferably 4-6 parts by weight.

[0099] Flame retardants can also be added to the composite film to improve its flame retardant properties. For example, they can be added to layers a and / or b, or to another layer c, where layer c is a flame-retardant functional layer. For instance, by weight of layer c, layer c may contain 30-80% by weight, preferably 40-70% by weight, of a propylene polymer and 20-70% by weight, preferably 30-60% by weight, of a flame retardant. This achieves an oxygen index ≥21%, preferably ≥23%, as determined according to the method specified in GB / T 2406-2008.

[0100] The flame retardant may be selected from at least one of the following: hydrates of metal or non-metal hydroxides and / or oxides, phosphorus-based flame retardants, boron-based flame retardants, antimony-based flame retardants, and intumescent flame retardants. The hydrates of metal or non-metal hydroxides and / or oxides may be at least one of aluminum, magnesium, boron, zinc hydroxides, and layered bimetallic hydroxides; the phosphorus-based flame retardant may be at least one of red phosphorus, phosphates, polyphosphates, and phosphate esters; the boron-based flame retardant may be boric acid and / or borates, preferably ammonium borate and / or zinc borate; the antimony-based flame retardant may be at least one of antimony trioxide, antimony pentoxide, and sodium antimonate; the intumescent flame retardant may be at least two of sulfuric acid, pentaerythritol or its dimer or trimer, butanethyl alcohol, cyclohexanehexyl alcohol, sorbitol, glucose, maltose, starch, resorcinol, ammonium polyphosphate, dicyandiamide, melamine, urea, melamine, glycine, expandable graphite, and carbon nanotubes. In one embodiment, the flame retardant is an intumescent flame retardant, preferably a mixture of ammonium polyphosphate and pentaerythritol, specifically, the weight ratio of ammonium polyphosphate to pentaerythritol is 0.5-5:1. In another embodiment, the flame retardant is a mixture of magnesium hydroxide and aluminum hydroxide, specifically, the weight ratio of magnesium hydroxide to aluminum hydroxide is 0.5-2:1. Flame-retardant polypropylene films prepared by adding flame retardants have advantages such as easy processing and good performance.

[0101] To impart a colored appearance to the composite film, a colorant can be added. The colorant can be a conventional choice in the art, including but not limited to at least one of azo pigments, phthalocyanine pigments, heterocyclic pigments, lake pigments, dyes, fluorescent whitening agents, and fluorescent pigments. All of the above colorants are commercially available. The colorant is preferably added to layer a. Based on 100 parts by weight of the matrix polymer in layer a, the content of the colorant can be 0.1-1 parts by weight, preferably 0.3-0.8 parts by weight. Layer a may also include a dispersant. The dispersant can improve the processability and uniformity between the matrix polymer component and the colorant in layer a. Its type, usage, and amount can all be conventional choices in the art. For example, the dispersant can be a low molecular weight polyethylene wax, and the weight content of the dispersant can be 20-30% by weight of the colorant.

[0102] A slip agent may also be added to the composite film of the present invention. The slip agent may be an amide-based slip agent, preferably at least one selected from erucamide, oleamide, stearamide, behenamide, stearyl erucamide, and ethylene bis-stearamide. Alternatively, the slip agent may be a mixture of an amide-based slip agent and a migration-resistant slip agent, wherein the amide-based slip agent is preferably at least one selected from erucamide, oleamide, stearamide, behenamide, stearyl erucamide, and ethylene bis-stearamide. The migration-resistant slip agent is preferably at least one selected from polytetrafluoroethylene microparticles, polyimide microparticles, polyamide microparticles, polycarbonate microparticles, organosilicon, nano-calcium carbonate, mica, and nano-silica. Preferably, the weight ratio of the amide-based slip agent to the migration-resistant slip agent is 1:20-1:1, more preferably 1:10-1:2. The particle size range of the migration-resistant slip agent contained in the slip agent can be 0.1-5μm, preferably 0.3-2μm.

[0103] The slip agent can be added to layer a and / or layer b, and the amount added can be 0.01-1.5% by weight, preferably 0.08-0.6% by weight, based on the total weight of the layers.

[0104] Preferably, a slip agent is added to both layer a and layer b.

[0105] Preferably, the molecular weight of the amide-based slip agent in layer b is not less than the molecular weight of the amide-based slip agent in layer a.

[0106] Preferably, layer a contains an amide-based slip agent, while layer b contains a mixture of an amide-based slip agent and a migration-resistant slip agent.

[0107] By adding a composite slip agent to the surface layer, the initial slip properties of the film are improved. The migration-resistant slip agent portion of the composite slip agent provides some slip properties without requiring a precipitation process. By controlling the particle size range, the heat-sealing and optical properties of the film can be maintained. In addition, the amide-based slip agent in the surface layer also provides some slip properties, further reducing the coefficient of friction of the film and improving its initial slip properties. On the other hand, the use of the composite slip agent and the combination of core and surface slip agents provide good high-temperature slip properties and heat-sealing performance retention.

[0108] The resulting composite film can have a surface friction coefficient of <0.3, preferably ≤0.23; after heating at 60°C for 24 hours, the change in the film surface friction coefficient is ≤0.02, preferably ≤0.01.

[0109] In addition, insulating additives can be added to the composite film of the present invention, thereby improving the electrical insulation properties of the propylene polymer composite film. Preferably, propylene grafted polymers can be used as insulating additives.

[0110] The propylene graft polymer can be added to layer a and / or layer b. The amount of propylene graft polymer added can be 5-45% by weight, based on the total weight of the layer.

[0111] In a preferred embodiment, layer a comprises, by weight of layer a, 50-90 wt%, preferably 55-75 wt%, homopolymer polypropylene, 5-45 wt%, preferably 10-30 wt%, propylene graft polymer, and 2-40 wt%, preferably 5-20 wt%, polyolefin elastomer; and by weight of layer b, layer b comprises 40-100 wt%, preferably 70-90 wt%, propylene random copolymer, and 0-60 wt%, preferably 10-30 wt%, polyolefin elastomer.

[0112] In another embodiment, layer a comprises, by weight of layer a, 50-100 wt%, preferably 75-95 wt%, of a propylene polymer and 0-50 wt%, preferably 5-25 wt%, of a polyolefin elastomer; and by weight of layer b, layer b comprises 50-90 wt%, 60-85 wt%, of a propylene random copolymer, 5-40 wt%, preferably 5-20 wt%, of a polyolefin elastomer and 2-40 wt%, preferably 5-20 wt%, of a propylene graft polymer.

[0113] The propylene graft polymer may include structural units derived from copolymer polypropylene and structural units derived from graft monomers grafted thereon.

[0114] The grafting monomer may be selected from acrylates; acrylic acids; styrene compounds; alkenyl-containing silanes; alkenyl-containing heterocyclic monomers; or a combination of anhydrides having at least one olefin unsaturation degree and alkenyl-containing polymeric monomers.

[0115] The melt flow rate of the propylene graft polymer at 230°C and 2.16 kg load can be 0.01-30 g / 10 min, preferably 0.05-20 g / 10 min, more preferably 0.1-10 g / 10 min, and even more preferably 0.2-8 g / 10 min.

[0116] The copolymerized polypropylene can be a propylene copolymer containing ethylene or higher α-olefins, or a mixture thereof. Specifically, the comonomer of the copolymerized polypropylene is selected from at least one of ethylene and C4-C8 α-olefins. The C4-C8 α-olefins include, but are not limited to, at least one of 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene. The comonomer is preferably ethylene and / or 1-butene, and more preferably, the copolymerized polypropylene is composed of propylene and ethylene.

[0117] In addition to the above-mentioned compositional characteristics, the copolymerized polypropylene also has at least one of the following characteristics: the comonomer content is 0.5-30 mol%, preferably 4-25 mol%; the xylene-soluble content is 2-80 wt%, preferably 18-75 wt%, more preferably 30-70 wt%; the comonomer content in the soluble matter is 10-70 wt%, preferably 10-50 wt%, more preferably 20-35 wt%; the intrinsic viscosity ratio of the soluble matter to polypropylene is 0.3-5, preferably 0.5-3, more preferably 0.8-1.3; the melt mass flow rate at 230°C and 2.16 kg load is 0.01-60 g / 10 min, preferably 0.05-35 g / 10 min, more preferably 0.5-15 g / 10 min; the melt temperature Tm is above 100°C, preferably 110-180°C, more preferably 120-170°C; and the weight-average molecular weight is 20 × 10⁻⁶. 4 -60×10 4 g / mol.

[0118] The copolymerized polypropylene can be any commercially available suitable polypropylene powder, or it can be produced by commonly used polymerization processes described in the literature. For example, it can be prepared according to the methods described in CN101679557A and CN101058654A.

[0119] In one embodiment, the propylene graft polymer may include structural units derived from copolymer polypropylene and structural units grafted thereon derived from acrylate monomers and optionally acrylic monomers. Based on the weight of the propylene graft polymer, the content of the grafted structural units derived from acrylate monomers and optionally acrylic monomers may be 0.3-7% by weight, preferably 0.8-5% by weight. In the propylene graft polymer, the molar ratio of structural units derived from acrylate monomers to structural units derived from acrylic monomers may be 1:0-2, preferably 1:0.125-1.

[0120] The acrylate monomer used as the grafting monomer can be any monomeric acrylate compound capable of polymerization by free radicals, and can be selected from at least one of the monomers having the structure shown in Formula I.

[0121]

[0122] R1, R2, and R3 are each independently selected from H, C1-C6 straight-chain alkyl groups, and C3-C6 branched alkyl groups; R4 is selected from the following substituted or unsubstituted groups: C1-C 20 Straight-chain alkyl, C3-C 20 Branched alkyl, C3-C 12 cycloalkyl, C3-C 12 Epoxyalkyl, C3-C 12 The substituted group is selected from at least one of halogen, amino, and hydroxyl groups.

[0123] Preferably, the acrylate monomer is selected from at least one of methyl methacrylate, sec-butyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, coconut oleate methacrylate, octadecyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate, and glycidyl methacrylate.

[0124] The acrylic monomer can be any acrylic compound that can be polymerized by free radicals, and can be selected from at least one of the monomers having the structure shown in Formula II;

[0125]

[0126] In Equation II, R 1 R 2 R 3 Each is independently selected from H, C1-C6 straight-chain alkyl, and C3-C6 branched alkyl.

[0127] Preferably, the acrylic monomer is selected from at least one of acrylic acid, methacrylic acid and 2-ethylacrylic acid.

[0128] In this invention, C3-C 12 Epoxyalkyl refers to an alkyl group that has 3-12 carbon atoms and is substituted with an epoxyalkyl group, such as ethylene oxide methyl.

[0129] In this invention, structural units derived from acrylic monomers may be absent or may coexist with structural units derived from acrylate monomers. Preferably, the molar ratio of structural units derived from acrylate monomers to structural units derived from acrylic monomers is 1:0-2, and more preferably 1:0.125-1.

[0130] The ratio of the total mass of the acrylate monomers and optionally other acrylic monomers to the mass of the copolymerized polypropylene is 0.1-10:100, preferably 0.5-8:100, and more preferably 0.8-7:100. The molar ratio of the acrylate monomers to the acrylic monomers is 1:0-2, preferably 1:0.125-1.

[0131] In another embodiment, the propylene graft polymer may include structural units derived from copolymer polypropylene and structural units derived from styrene monomers. The content of grafted structural units derived from styrene monomers in the propylene graft polymer may be 0.5-14% by weight, preferably 1-7.5% by weight, and more preferably 1.5-5% by weight.

[0132] The styrene monomer used as the grafting monomer can be any styrene monomer compound capable of polymerization by free radicals, and can be selected from at least one of the monomers having the structure shown in Formula III, the structure shown in Formula IV, and the structure shown in Formula V.

[0133]

[0134] In Equation III, R 1 R 2 R 3 Each is independently selected from H, substituted or unsubstituted C1-C6 alkyl groups; R 4 -R 8 Each is independently selected from H, halogen, hydroxyl, amino, phosphate group, sulfonic acid group, substituted or unsubstituted C1-C. 12 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 ester group, substituted or unsubstituted C1-C 12 The amine group, wherein the substituent group is selected from halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C 12 Alkyl, C3-C 12 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 ester group, C1-C 12 The amino group; preferably, R 1 R 2 R 3 Each is independently selected from H, substituted or unsubstituted C1-C3 alkyl groups, R 4 -R 8Each is independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy;

[0135]

[0136] In formula IV, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C6 alkyl groups; R4-R 10 Each is independently selected from H, halogen, hydroxyl, amino, phosphate group, sulfonic acid group, substituted or unsubstituted C1-C. 12 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 ester group, substituted or unsubstituted C1-C 12 The amine group, wherein the substituent group is selected from halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C 12 Alkyl, C3-C 12 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 ester group, C1-C 12 The amino group; preferably, R1, R2, R3 are each independently selected from H, substituted or unsubstituted C1-C3 alkyl groups, R4-R 10 Each of the substituents is independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, wherein the substituent is selected from halogen, hydroxyl, amino, C1-C6 alkyl, C1-C6 alkoxy;

[0137]

[0138] In formula V, R1', R2', and R3' are each independently selected from H, substituted or unsubstituted C1-C6 alkyl groups; R4'-R 10 Each group is independently selected from H, halogen, hydroxyl, amino, phosphate, sulfonic acid, substituted or unsubstituted C1-C. 12 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 ester group, substituted or unsubstituted C1-C 12 The amine group, wherein the substituent group is selected from halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C 12 Alkyl, C3-C 12 cycloalkyl, C1-C 12 alkoxy groups, C1-C12 ester group, C1-C 12 The amino group; preferably, R1', R2', R3' are each independently selected from H, substituted or unsubstituted C1-C3 alkyl groups, R4'-R 10 Each of the substituents is independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, wherein the substituent is selected from halogen, hydroxyl, amino, C1-C6 alkyl, C1-C6 alkoxy.

[0139] Preferably, the styrene monomer is selected from at least one of styrene, α-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, monosubstituted or polysubstituted styrene, monosubstituted or polysubstituted α-methylstyrene, monosubstituted or polysubstituted 1-vinylnaphthalene, and monosubstituted or polysubstituted 2-vinylnaphthalene; the substituent group is preferably selected from at least one of halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, C1-C8 straight-chain alkyl, C3-C8 branched alkyl or cycloalkyl, C1-C6 straight-chain alkoxy, C3-C8 branched alkoxy or cyclic alkoxy, C1-C8 straight-chain ester, C3-C8 branched ester or cyclic ester, C1-C8 straight-chain amino, and C3-C8 branched amino or cyclic amino.

[0140] More preferably, the styrene monomer is selected from at least one of styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, and 4-methylstyrene.

[0141] The mass ratio of the styrene monomer to the copolymer polypropylene can be 0.5-16:100, preferably 1-12:100, and more preferably 2-10:100.

[0142] In another embodiment, the propylene graft polymer comprises structural units derived from copolymer polypropylene and structural units derived from alkenyl-containing silane monomers. Based on the weight of the propylene graft polymer, the content of the structural units grafted onto the propylene graft polymer b from alkenyl-containing silane monomers can be 0.2-6% by weight, preferably 0.2-2.5% by weight.

[0143] The alkenyl-containing silane monomer used as the grafting monomer can be any monomeric silane compound capable of free radical polymerization, and can be selected from at least one of the monomers having the structure shown in Formula VI.

[0144]

[0145] In equation VI, R1 is C2-C 12The alkenyl group, preferably a monounsaturated alkenyl group; R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C. 12 Straight-chain alkyl, substituted or unsubstituted C3-C 12 Branched alkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 The acyloxy group; preferably, R1 is a C2-C6 alkenyl group, more preferably a monounsaturated alkenyl group; R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C6 straight-chain alkyl groups, substituted or unsubstituted C3-C6 branched alkyl groups, substituted or unsubstituted C1-C6 alkoxy groups, and substituted or unsubstituted C1-C6 acyloxy groups.

[0146] More preferably, the alkenyl-containing silane monomer is selected from at least one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriisopropoxysilane, vinyltritert-butoxysilane, vinyltriacetoxysilane, methylvinyldimethoxysilane, ethylvinyldiethoxysilane, allyltriethoxysilane, allyltrimethoxysilane, allyltriisopropoxysilane, vinyltri(β-methoxyethoxy)silane, allyltri(β-methoxyethoxy)silane, allyltritert-butoxysilane, allyltriacetoxysilane, methylallyldimethoxysilane, and ethylallyldiethoxysilane.

[0147] The mass ratio of the alkenyl-containing silane monomer to the copolymerized polypropylene can be 0.5-12:100, preferably 0.8-9:100, and more preferably 1-6:100.

[0148] In another embodiment, the propylene graft polymer comprises structural units derived from copolymer polypropylene, structural units derived from anhydride monomers, and structural units derived from alkenyl-containing polymeric monomers. The alkenyl-containing polymeric monomer is selected from at least one of vinyl acetate, styrene, α-methylstyrene, (meth)acrylate, vinyl alkyl ether, vinylpyrrolidone, vinylpyridine, vinylimidazolium, and acrylonitrile. The anhydride is preferably selected from maleic anhydride and / or itaconic anhydride. The content of the structural units grafted onto the anhydride monomer and the alkenyl-containing polymeric monomer can be 0.1-5% by weight, preferably 0.4-3% by weight. The content of the structural units grafted onto the anhydride monomer can be 0.05-2% by weight, preferably 0.2-0.7% by weight. The molar ratio of the structural units derived from the anhydride monomer to the structural units derived from the alkenyl-containing polymeric monomer can be 1:1-20, preferably 1:1-10. The alkenyl-containing polymeric monomer used as the graft monomer is preferably selected from at least one of monomers having the structure shown in Formula 1.

[0149]

[0150] In Formula 1, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted alkyl groups; R4 is selected from substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryl groups, substituted or unsubstituted ester groups, substituted or unsubstituted carboxyl groups, substituted or unsubstituted cycloalkyl or heterocyclic groups, and cyano groups.

[0151] Preferably, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C6 alkyl groups; more preferably, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C3 alkyl groups; R4 is selected from substituted or unsubstituted C1-C6 alkyl groups. 20 Alkyl, substituted or unsubstituted C1-C 20 Alkoxy, substituted or unsubstituted C6-C 20 aryl, substituted or unsubstituted C1-C 20 Ester group, substituted or unsubstituted C1-C 20 Carboxyl group, substituted or unsubstituted C3-C 20 The substituted group is a cycloalkyl or heterocyclic group, or a cyano group, wherein the substituted group is a halogen, hydroxyl, amino, C1-C6 alkyl, or C3-C6 cycloalkyl; preferably, R4 is selected from substituted or unsubstituted C1-C6 groups. 12 Alkyl, substituted or unsubstituted C1-C 18 Alkoxy, substituted or unsubstituted C6-C 12 aryl, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 Carboxyl group, substituted or unsubstituted C3-C 12 The substituted group is a cycloalkyl or heterocyclic group, or a cyano group, wherein the substituted group is a halogen, a C1-C6 alkyl group, or a C3-C6 cycloalkyl group; more preferably, R4 is selected from substituted or unsubstituted C1-C6 alkyl groups, substituted or unsubstituted C1-C6 cycloalkyl groups, or C3-C6 cycloalkyl groups. 12 The group may contain alkoxy, substituted or unsubstituted C6-C8 aryl, substituted or unsubstituted C1-C6 ester, substituted or unsubstituted C1-C6 carboxyl, substituted or unsubstituted C3-C6 cycloalkyl or heterocyclic, or cyano. Specifically, preferably, the heterocyclic group is selected from imidazole, pyrazol, carbazole, pyrrolidone, pyridinyl, piperidinyl, caprolactam, pyrazinyl, thiazolyl, purine, morpholinyl, or oxazolinyl.

[0152] More preferably, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C6 alkyl groups;

[0153] R4 is selected from the group shown in Formula 2, the group shown in Formula 3, the group shown in Formula 4, the group shown in Formula 5, a combination of the group shown in Formula 5 and the group shown in Formula 6, and a heterocyclic group;

[0154]

[0155] In Equation 2, R 4 -R 8 Each is independently selected from H, halogen, hydroxyl, amino, phosphate group, sulfonic acid group, substituted or unsubstituted C1-C. 12 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 ester group, substituted or unsubstituted C1-C 12 The substituted amino group, wherein the substituted group is selected from halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C 12 Alkyl, C3-C 12 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 ester group, C1-C 12 The amino group; preferably, R 4 -R 8 Each is independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy;

[0156]

[0157] In Equation 3, R4-R 10 Each is independently selected from H, halogen, hydroxyl, amino, phosphate group, sulfonic acid group, substituted or unsubstituted C1-C. 12 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 ester group, substituted or unsubstituted C1-C 12 The substituted amino group, wherein the substituted group is selected from halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C 12 Alkyl, C3-C 12 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 ester group, C1-C 12 The amino group; preferably, R4-R 10 Each of the groups is independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, wherein the substituted group is selected from halogen, hydroxyl, amino, C1-C6 alkyl, C1-C6 alkoxy;

[0158]

[0159] In Equation 4, R4'-R 10 Each group is independently selected from H, halogen, hydroxyl, amino, phosphate, sulfonic acid, substituted or unsubstituted C1-C. 12 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 ester group, substituted or unsubstituted C1-C 12 The substituted amino group, wherein the substituted group is selected from halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C 12 Alkyl, C3-C 12 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 ester group, C1-C 12 The amino group; preferably, R4'-R 10 Each of the following is independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, wherein the substituted group is selected from halogen, hydroxyl, amino, C1-C6 alkyl, C1-C6 alkoxy;

[0160]

[0161] In Equation 5, R m Selected from the following groups, substituted or unsubstituted: C1-C 20 Straight-chain alkyl, C3-C 20 Branched alkyl, C3-C 12 cycloalkyl, C3-C 12 Epoxyalkyl, C3-C 12 The substituted group is selected from at least one of halogen, amino, and hydroxyl groups.

[0162] More preferably, the alkenyl-containing polymeric monomer is selected from at least one of vinyl acetate, styrene, α-methylstyrene, (meth)acrylate, vinyl alkyl ether, vinylpyrrolidone, vinylpyridine, vinylimidazolium, and acrylonitrile; the (meth)acrylate is preferably at least one of methyl (meth)acrylate, ethyl (meth)acrylate, and glycidyl (meth)acrylate. Preferably, the alkenyl-containing polymeric monomer is selected from vinyl acetate, styrene, and α-methylstyrene. More preferably, the alkenyl-containing polymeric monomer is styrene.

[0163] In the propylene graft polymer containing anhydride groups, the molar ratio of structural units derived from (maleic) anhydride monomers to structural units derived from alkenyl-containing polymer monomers can be 1:1-20, preferably 1:1-10.

[0164] The acid anhydride may be selected from acid anhydrides having at least one degree of olefin unsaturation; more preferably, the acid anhydride is selected from maleic anhydride and / or itaconic anhydride; even more preferably, the acid anhydride is maleic anhydride.

[0165] The mass ratio of the total mass of the anhydride monomer and the alkenyl-containing polymeric monomer to the mass of the copolymerized polypropylene can be 0.1-8:100, preferably 0.3-5:100. The mass amount of the anhydride monomer can be 5-100 wt% of the mass amount of the alkenyl-containing polymeric monomer, preferably 10-100 wt%.

[0166] In another embodiment, the propylene graft polymer comprises structural units derived from copolymerized polypropylene and structural units derived from alkenyl-containing heterocyclic monomers. Based on the weight of the propylene graft polymer, the content of the grafted structural units derived from alkenyl-containing heterocyclic monomers can be 0.5-6% by weight, preferably 0.5-4% by weight.

[0167] The alkenyl-containing heterocyclic monomer used as the grafting monomer can be any alkenyl-containing heterocyclic compound capable of free radical polymerization, selected from at least one of the following: alkenyl-substituted imidazole, alkenyl-substituted pyrazole, alkenyl-substituted carbazole, alkenyl-substituted pyrrolidone, alkenyl-substituted pyridine or pyridine salt, alkenyl-substituted piperidine, alkenyl-substituted caprolactam, alkenyl-substituted pyrazine, alkenyl-substituted thiazole, alkenyl-substituted purine, alkenyl-substituted morpholine, and alkenyl-substituted oxazoline; preferably, the alkenyl-containing heterocyclic monomer is a monoalkenyl-containing heterocyclic monomer.

[0168] Specifically, the alkenyl-containing heterocyclic monomer may be selected from at least one of the following: 1-vinylimidazolium, 2-methyl-1-vinylimidazolium, N-allylimidazolium, 1-vinylpyrazole, 3-methyl-1-vinylpyrazole, vinylcarbazole, N-vinylpyrrolidone, 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, vinylpyridine N-oxide, vinylpyridine salt, vinylpiperidine, N-vinylcaprolactam, 2-vinylpyrazine, N-vinylpiperazine, 4-methyl-5-vinylthiazole, N-vinylpurine, vinylmorpholine, and vinyloxazoline.

[0169] The mass ratio of the alkenyl-containing heterocyclic monomer to the copolymer polypropylene can be 0.3-12:100, preferably 0.5-10:100.

[0170] The grafting reaction described in this article is a free radical polymerization reaction. Through free radical polymerization, the grafting monomers form a covalent bond with the copolymer polypropylene (grafting).

[0171] Preferably, the propylene graft polymer can be prepared by solid-state grafting reaction of copolymerized polypropylene and grafting monomer, for example, according to the method described in Chinese patent applications with application numbers 202011195771.2, 202011191001.0, 202011195799.6, 202011190917.4, and 202011195819.X.

[0172] Specifically, the propylene graft polymer can be prepared by a method including the following steps: in the presence of an inert gas, a reaction mixture comprising copolymer polypropylene and graft monomer is subjected to a solid-phase grafting reaction to obtain the propylene graft polymer.

[0173] The solid-phase grafting reaction can be carried out using various methods conventional in the art, such as forming active graft sites on the copolymer polypropylene in the presence of grafting monomers, or first forming active graft sites on the copolymer polypropylene and then treating it with grafting monomers. Graft sites can be formed by treatment with free radical initiators, or by high-energy ionizing radiation or microwave treatment. Free radicals generated in the polymer as a result of chemical or radiation treatment form graft sites on the polymer and initiate monomer polymerization at these sites.

[0174] Preferably, the grafting site is initiated by a free radical initiator and a grafting reaction is further carried out. In this case, the reaction mixture further includes a free radical initiator; more preferably, the free radical initiator is selected from peroxide free radical initiators and / or azo free radical initiators.

[0175] The peroxide radical initiator is preferably selected from at least one of benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, dodecyl peroxide, tert-butyl peroxide, diisopropyl peroxide, tert-butyl peroxide, and dicyclohexyl peroxide; the azo radical initiator is preferably azobisisobutyronitrile and / or azobisisoheptanenitrile.

[0176] More preferably, the grafting site is initiated by a peroxide-based free radical initiator and the grafting reaction is further carried out.

[0177] In addition, the grafting reaction can also be carried out by the methods described in CN106543369A, CN104499281A, CN102108112A, CN109251270A, CN1884326A and CN101492517B.

[0178] The ratio of the mass of the free radical initiator to the total mass of the grafting monomer can be 0.1-10:100, preferably 0.5-5:100.

[0179] The grafting reaction can be carried out at a temperature of 30-130℃, preferably 60-120℃, and for a time of 0.5-10h, preferably 1-5h.

[0180] The “reaction mixture” includes all materials added to the grafting reaction system. The materials can be added all at once or at different stages of the reaction.

[0181] The reaction mixture may further include a dispersant, preferably an aqueous solution of water or sodium chloride. The mass percentage of the dispersant is preferably 50-300% of the mass of the copolymer polypropylene.

[0182] The reaction mixture may further include an interface agent, which is an organic solvent that has a swelling effect on polyolefins, preferably at least one of the following organic solvents that have a swelling effect on copolymer polypropylene: ether solvents, ketone solvents, aromatic solvents, alkane solvents; more preferably at least one of the following organic solvents: chlorobenzene, polychlorinated benzene, alkanes or cycloalkanes with more than C6 carbon atoms, benzene, C1-C4 alkyl-substituted benzene, C2-C6 aliphatic ethers, C3-C6 aliphatic ketones, decahydronaphthalene; even more preferably at least one of the following organic solvents: benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, diethyl ether, acetone, hexane, cyclohexane, decahydronaphthalene, heptane. The mass content of the interface agent is preferably 1-35% of the mass of copolymer polypropylene, more preferably 10-25%.

[0183] The reaction mixture may further include an organic solvent as a solvent for dissolving the solid free radical initiator. The organic solvent preferably includes at least one of C2-C5 alcohols, C2-C4 ethers, and C3-C5 ketones; more preferably, it includes at least one of C2-C4 alcohols, C2-C3 ethers, and C3-C5 ketones; and most preferably, it includes at least one of ethanol, diethyl ether, and acetone. The mass content of the organic solvent is preferably 1-35% of the mass of the copolymerized polypropylene.

[0184] During the grafting reaction, the grafting monomers can polymerize individually or together to form a certain amount of ungrafted polymer. Therefore, the propylene grafted polymer can include both the product (crude product) directly obtained from copolymerized polypropylene and grafting monomers via a grafting reaction, and the grafted modified polypropylene pure product obtained by further purification of the product. Therefore, the preparation method may optionally include a step of purifying the crude product. The purification can be carried out using various methods conventional in the art, such as extraction.

[0185] Preferably, the grafting efficiency of the grafting reaction is controlled at 5-100%, more preferably 30-100%, further preferably 25-80%, or 35-60%. The concept of grafting efficiency is well known to those skilled in the art, and refers to the amount of grafting monomers on the graft / the total amount of grafting monomers fed into the reaction.

[0186] The inert gas can be any of the inert gases commonly used in the field, including but not limited to nitrogen and argon.

[0187] Layer structure and properties of composite thin films

[0188] The composite film of the present invention can consist of only layer a and layer b, that is, a double-layer film.

[0189] In an alternative embodiment, in addition to layers a and b, the composite film of the present invention may also include one or more additional layers, i.e., three or more layers, thereby forming a three-layer film or a film with more than three layers, where layer b is the surface layer of the composite film. The composition of this additional layer may be the same as or different from that of layer a or layer b. This layer may also be formed by mixing the components of layer a and the components of layer b. For example, when the composite film is a three-layer film, this additional layer is called layer c, with layers b and c located on opposite sides of layer a, i.e., layer c is located on the side of layer a opposite to layer b, and in this case, layer c is also the surface layer. When the composite film is five layers, it is possible that two layers b serve as the top and bottom surface layers, two layers c serve as the middle layers, and one layer a serves as the core layer.

[0190] In this invention, the thicknesses of layers a, b, and optionally c, and other layers, are not particularly limited. The ratio of the sum of the thicknesses of all layers except layer a to the thickness of layer a can be 1:6 to 2:1, for example, 1:5.5, 1:5, 1:4.5, 1:4, 1:3.5, 1:3, 1:2.5, 1:2, 1:1.5, 1:1, 1.5:1, and any values ​​between them, preferably 1:4 to 2:1, more preferably 1:2 to 1:1. Such composite films can advantageously possess better mechanical properties (e.g., tensile strength) and performance stability.

[0191] Unexpectedly, it has been found that, due to the presence of dispersed, parallel-arranged strip-shaped rubber phases derived from propylene impact copolymers in the composite film of the present invention, the composite film of the present invention can simultaneously possess excellent impact resistance and optical properties, and even excellent mechanical properties (e.g., tensile strength) and / or excellent heat-sealing properties, exhibiting good heat-sealing strength at relatively low heat-sealing temperatures.

[0192] When, in addition to the rubber phase from the propylene impact copolymer mentioned above, the composite film of the present invention also contains homopolymer polypropylene and polyolefin elastomer, the rubber phase and inelastic portion of the propylene impact copolymer will have a synergistic interaction with the polymer spherulites formed by homopolymer polypropylene and the rubber phase of polyolefin elastomer, so that the impact resistance and optical properties of the composite film can be further improved simultaneously, and even its mechanical properties can be improved.

[0193] The composite film according to the invention may advantageously possess one or more of the following properties, preferably all of them:

[0194] 1) The impact strength of the pendulum is ≥0.4J, for example ≥0.5J, 0.6J or 0.7J, preferably ≥0.9J, more preferably ≥1.1J, for example ≥1.5J, or even ≥1.8J;

[0195] 2) The haze of the film is less than 7%, preferably ≤5%, more preferably ≤3%, for example ≤2.5%, and even more preferably ≤2%;

[0196] 3) The longitudinal (MD) tensile strength is ≥40MPa, preferably ≥50MPa;

[0197] 4) The heat-sealing strength at 150°C is ≥12N / 15mm, preferably ≥15N / 15mm, more preferably ≥17N / 15mm, more preferably ≥18N / 15mm, or even ≥19N / 15mm, for example ≥20N / 15mm;

[0198] 5) The thickness deviation in the MD direction is not greater than 1.3, for example, not greater than 1.0, preferably not greater than 0.5;

[0199] 6) The thickness deviation in the TD direction shall not exceed 1.5, for example, not exceed 1.3, preferably not exceed 0.75 or not exceed 0.8;

[0200] 7) The impact resistance deviation in the MD direction is not greater than 0.05, preferably not greater than 0.03;

[0201] 8) The deviation of impact resistance in the TD direction is not greater than 0.07, preferably not greater than 0.05, and more preferably not greater than 0.04;

[0202] 9) Surface energy ≥29mN / m, for example ≥33mN / m, ≥34.5mN / m, preferably ≥35mN / m;

[0203] 10) Volume resistivity ≥ 1.5 × 10⁻⁶ 15 Ω·m, preferred selection rate ≥2.0×10 15 Ω·m.

[0204] The measurement methods and standards for the aforementioned performance are as follows:

[0205] Pendulum impact strength: in accordance with standard GB / T 8809-2015;

[0206] Thin film haze: in accordance with standard GB / T 2410-2008;

[0207] Tensile strength: in accordance with standard GB / T 1040.3-2006, along the longitudinal direction of the film;

[0208] Heat sealing strength: According to standard QB / T 2358, the heat sealing temperature during sample preparation is 150℃, the heat sealing pressure is 0.2MPa, and the heat sealing time is 3s.

[0209] Thickness deviation in the MD direction: The film thickness was measured using a Mitutoyo 7301 thickness gauge (Japan). (See attached...) Figure 1a As shown, after the film is trimmed, a point is taken every 1 meter along the MD direction on the center line of the film, for a total of 10 points. The thickness of each point is tested according to the method specified in GB / T8809-2015, and the average value is taken as the thickness (MD) of the film. The standard deviation of the thickness is calculated based on the above data, which is taken as the thickness deviation in the MD direction.

[0210] Thickness deviation in the TD direction: as shown in the attached document. Figure 1b As shown, 10 points are uniformly selected along the TD direction at any point on the film, and the thickness of each point is tested according to the method specified in GB / T 8809-2015. The average value is taken as the thickness (TD) of the film. The standard deviation of the thickness is calculated based on the above data and is taken as the thickness deviation in the TD direction.

[0211] Impact strength deviation in the MD direction: as shown in the attached figure. Figure 1a As shown, after the film is trimmed, a point is taken every 1 meter along the MD direction on the center line of the film, for a total of 10 points. The impact strength of each point is tested according to the method specified in GB / T8809-2015, and the average value is taken as the impact strength (MD) of the film. The standard deviation of the impact strength is calculated based on the above data and used as the impact strength deviation in the MD direction.

[0212] Impact strength deviation in the TD direction: as shown in the attached figure. Figure 1b As shown, along the TD direction at any point on the film, 10 points are uniformly selected, and the impact strength of each point is tested according to the method specified in GB / T 8809-2015. The average value is taken as the impact strength (TD) of the film. The standard deviation of the impact strength is calculated based on the above data and is taken as the impact strength deviation in the TD direction.

[0213] Thin film surface energy: determined according to the method specified in GB / T 14216-2008.

[0214] Volume resistivity: determined according to the method specified in GB / T 1410-2006.

[0215] Preparation of composite thin films

[0216] A second aspect of the present invention provides a method for preparing the composite film of the present invention. The method of the present invention includes extruding and casting a raw material composition for forming the layers to form the composite film.

[0217] According to the present invention, prior to the extrusion process, the elastic portion of the propylene impact copolymer used in the raw material composition can be formed into a granular rubber phase, wherein the average particle size of the rubber phase is less than or equal to 1.8 μm, preferably less than or equal to 1.5 μm, and the maximum particle size does not exceed 2.5 μm, preferably not exceeding 2 μm, as determined by SEM observation of the cross-section of the sample.

[0218] The rubber phase is typically spherical or nearly spherical.

[0219] In this article, spherical and near-spherical refer to particles with an aspect ratio substantially in the range of 1-2. "Substantially" means that at least 90% of the rubber phase particles have an aspect ratio in the range of 1-2.

[0220] The average and maximum particle size of the rubber phase in the propylene impact copolymer of the raw material were determined by scanning electron microscopy (SEM) of the cross-section of impact test specimens prepared according to the method specified in standard GB / T8809-2015. For spherical particles, the particle diameter was measured; for near-spherical particles, the longitudinal axis of the particle (the distance between the two farthest points on the particle profile) was measured. The average value of the above dimensions of 50 sample points was obtained by observing SEM images as the average particle size, and the maximum value of the above dimensions among the sample points was taken as the maximum particle size.

[0221] According to the present invention, by controlling the size of the rubber phase in the raw material propylene impact copolymer, the size of the rubber phase in the composite film can be made to be within the specific range described in the present invention.

[0222] Prior to the extrusion process, the components of the polymer composition used to prepare the layers (including optional additives such as antioxidants, lubricants and other film-forming aids) can be mixed or blended and optionally granulated.

[0223] The granulation process can be carried out as follows: The components of propylene polymer composition A (for layer a), propylene polymer composition B (for layer b), and optional polymer compositions (for other layers), along with optional additives, are mixed uniformly in a high-speed mixer. The uniformly mixed material is then added to a twin-screw extruder for melt mixing and uniform extrusion granulation, followed by drying to obtain granules. The processing temperature of the twin-screw extruder can be controlled at 170-230°C.

[0224] The resulting granules are then extruded and cast to form a composite film. The extrusion casting process can be carried out using conventional methods and common equipment. The extrusion casting method may include feeding granules for preparing the polymer composition of each layer into multiple extruders. After co-extrusion and composite flow from the extruder dies, the granules sequentially pass through casting rollers and traction rollers, followed by edge trimming and winding to obtain the composite film. The extrusion casting temperature can be controlled between 170-230°C. The temperature of the casting rollers can be between 10-50°C.

[0225] According to the preparation method of the present invention, the rubber phase contained in the propylene impact copolymer used as raw material is deformed during the preparation process of the composite film, changing from a spherical or near-spherical shape to a strip shape, and oriented in a certain direction, i.e., arranged in parallel, and such microstructure is maintained in the final composite film product, thereby obtaining a composite film with good impact resistance and optical properties according to the present invention.

[0226] Advantageously, the polyolefin elastomer used also deforms during the preparation of the composite film, becoming a strip-shaped rubber phase and oriented in a certain direction, i.e., parallel arrangement. This microstructure is maintained in the final composite film product, while interacting synergistically with the rubber phase from the propylene impact copolymer, thereby further improving the impact resistance, optical properties, and other properties (mechanical properties, heat-sealing properties, film uniformity, etc.) of the composite film.

[0227] The resulting composite film can be stretched in subsequent processes, such as biaxial stretching, which can advantageously further improve the mechanical properties of the composite film.

[0228] According to some embodiments of the present invention, the method for preparing the composite film includes granulating the propylene polymer composition A and the propylene polymer composition B, followed by extrusion casting and stretching to obtain the composite film.

[0229] Applications of composite films

[0230] A third aspect of the present invention provides the application of the composite film of the present invention in the field of packaging materials.

[0231] Because the composite film of the present invention can simultaneously possess good impact resistance and optical properties, and even good tensile properties and / or good heat-sealing strength at lower heat-sealing temperatures, and even good thickness and / or performance uniformity, the composite film of the present invention is particularly suitable for high-end packaging applications, such as fields requiring both high impact resistance and optical properties, such as battery packaging materials, electronic product packaging, and high-end food packaging. The packaging materials may, for example, include those comprising aluminum-plastic composite films.

[0232] When using the composite film of the present invention, layer a serves as the core layer, i.e., the layer relatively far from the medium that the composite film will contact, and layer b serves as the surface layer, i.e., the layer close to the medium that the composite film will contact. The medium is, for example, the electrolyte that contacts battery packaging materials.

[0233] Accordingly, a fourth aspect of the invention provides packaging materials comprising the composite film of the invention. The packaging material may be, for example, battery packaging materials, electronic product packaging materials, or food packaging materials, particularly high-end food packaging materials. The packaging material may, for example, comprise aluminum-plastic composite films. Detailed Implementation

[0234] The present invention will be further illustrated below with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0235] In the following embodiments and comparative examples:

[0236] The film casting equipment was purchased from Labtech GmbH in Sweden, model LCR400.

[0237] The properties of the raw materials, polymer compositions, and films were measured using the following methods:

[0238] (1) Melt mass flow rate (MFR): The test was conducted according to the method specified in GB / T 3682-2000, with a test temperature of 230℃ and a load of 2.16kg.

[0239] (2) Tensile strength of film: The tensile strength of film shall be determined in accordance with the method specified in GB / T 1040.3-2006.

[0240] (3) Calculation of the impact strength and impact strength deviation of the diaphragm pendulum: The test was conducted according to the method specified in GB / T 8809-2015; specifically,

[0241] As attached Figure 1a As shown, after the film is trimmed, a point is taken every 1 meter along the MD direction on the center line of the film, for a total of 10 points. The impact strength of each point is tested according to the method specified in GB / T 8809-2015, and the average value is taken as the impact strength (MD) of the film. The standard deviation of the impact strength is calculated based on the above data and used as the impact strength deviation in the MD direction.

[0242] As attached Figure 1b As shown, along the TD direction at any point on the film, 10 points are uniformly selected, and the impact strength of each point is tested according to the method specified in GB / T 8809-2015. The average value is taken as the impact strength (TD) of the film. The standard deviation of the impact strength is calculated based on the above data and is taken as the impact strength deviation in the TD direction.

[0243] (4) Film haze: The haze shall be determined in accordance with the method specified in GB / T 2410-2008.

[0244] (5) Film heat seal strength: The test shall be conducted in accordance with the method specified in QB / T 2358. During sample preparation, the heat seal temperature is 150℃, the heat seal pressure is 0.2MPa, and the heat seal time is 3s.

[0245] (6) Isochronism: through 13 The carbon NMR spectrum of the propylene polymer was determined at 400 MHz using a Bruker AVANCE III nuclear magnetic resonance spectrometer (NMR) from Switzerland. 13 C-NMR was performed using deuterated o-dichlorobenzene as the solvent, with a sample concentration of 250 mg sample / 2.5 mL solvent. To prevent oxidative degradation of the sample during dissolution and data acquisition, 2 mg of 2,6-di-tert-butyl-4-methylphenol antioxidant (BHT) was added to the sample. The sample was dissolved at 140 °C, and data were collected. 13 C-NMR, test temperature 125℃, probe size 10 mm, 90° pulse, sampling time AQ 5 seconds, delay time D1 1 second, 6000 scans. The isotacticity was determined by the content of the two-unit group isotactic [mm].

[0246] (7) Molecular weight distribution (Mw / Mn): Determined by gel permeation chromatography (GPC) using a PL-GPC 220 gel permeation chromatograph manufactured by Polymer Laboratories, UK, combined with an IR5 infrared detector. The chromatographic column in the gel permeation chromatograph consisted of three PLgel 10μm MIXED-B columns connected in series. The solvent and mobile phase were both 1,2,4-trichlorobenzene (containing 0.3 g / 1000 mL of antioxidant 2,6-di-tert-butyl-p-cresol). The column temperature was 150℃, and the flow rate was 1.0 mL / min. The EasiCal PS-1 narrow distribution polystyrene standard manufactured by PL was used for universal standardization.

[0247] (8) Film thickness and thickness deviation test: The film thickness was tested using a Mitutoyo 7301 thickness gauge from Japan. (See attached...) Figure 1a As shown, after the film is trimmed, a point is taken every 1 meter along the MD direction on the center line of the film, for a total of 10 points. The thickness of each point is tested according to the method specified in GB / T 8809-2015, and the average value is taken as the thickness (MD) of the film. The standard deviation of the thickness is calculated based on the above data, which is taken as the thickness deviation in the MD direction.

[0248] As attached Figure 1bAs shown, 10 points are uniformly selected along the TD direction at any point on the film, and the thickness of each point is tested according to the method specified in GB / T 8809-2015. The average value is taken as the thickness (TD) of the film. The standard deviation of the thickness is calculated based on the above data and is taken as the thickness deviation in the TD direction.

[0249] (9) Calculation of standard deviation (S): Calculated according to formula (a).

[0250]

[0251] in, The average value of the measured data X1, X2...Xn is represented by N, which is the total number of data used.

[0252] (10) Determination of shear viscosity: The shear viscosity was measured using a Rheograph 25 capillary rheometer from GOTTFERT GmbH, Germany, according to the method described in ISO 11443:2014. The capillary rheometer temperature was set to 230℃, the die capillary length to 30mm, the capillary length-to-diameter ratio to 30:1, and the preheating time to 300 seconds. The shear rate was then measured. 160s -1 and 640s -1 The shear stress (δ) is calculated, and the shear viscosity η at the corresponding shear rate is calculated according to formula (b). 160 and η 640 .

[0253]

[0254] In the examples and comparative examples, propylene polymer composition A was subjected to a shear rate of 160 s. -1 and 640s -1 The shear viscosity at the following values ​​is denoted as ηA. 160 and ηA 640 The propylene polymer composition B was subjected to a shear rate of 160 s⁻¹. -1 and 640s -1 The shear viscosity at the following values ​​is denoted as ηB. 160 and ηB 640 Let P represent propylene polymer composition A and propylene polymer composition B at a shear rate of 160 s. -1 The difference in shear viscosity (ηA) 160 -ηB 160 ) and 640s -1 The difference in shear viscosity (ηA) 640 -ηB 640 The ratio of ηA to ηA 160 -ηB 160 ) / (ηA 640 -ηB640 ).

[0255] (11) Atomic force microscopy (AFM) images: A Bruker Dimension FastScan Icon atomic force microscope was used to scan and observe the cross-section of the thin film sample cut along the transverse direction using quantitative nanomechanical scanning mode.

[0256] (12) Dimensions and aspect ratio of the rubber phase in the film: The cross-section of the film sample cut along the transverse direction was scanned and observed using the quantitative nanomechanical scanning mode of the DimensionFastScan Icon atomic force microscope of Bruker Corporation, USA. The dimensions of the rubber phase were measured, calculated and statistically analyzed. The length between the intersection points of the longest straight line that intersects the object's outline with the vertical axis, the vertical axis (the distance between the two farthest points on the object's outline), and the aspect ratio were obtained based on 200 sample points.

[0257] (13) Average and maximum particle size of the rubber phase of the propylene impact copolymer in the raw material: The cross-section of the impacted sample after gold sputtering was scanned and observed using a COXEM EM-30AX scanning electron microscope from South Korea. The particle size of the rubber phase was measured and statistically analyzed to obtain the average and maximum particle size. For spherical particles, the diameter of the particles was measured; for near-spherical particles, the longitudinal axis of the particles (the distance between the two points furthest apart on the outline of the object) was measured. Based on 50 sample points, the maximum value of the above dimensions was obtained as the maximum particle size, and the average value of the above dimensions was calculated as the average particle size.

[0258] (14) Content of copolymerized ethylene units, ethylene unit content, and ethylene unit group [EEE] content in propylene impact copolymers: through... 13 C NMR determination.

[0259] 13 C10 NMR was performed using a 400MHz nuclear magnetic resonance spectrometer (AVANCE III) from Bruker, Switzerland. The solvent was deuterated o-dichlorobenzene, with a ratio of 250 mg sample to 2.5 ml solvent. To prevent oxidative degradation of the sample during dissolution and data acquisition, 2 mg of BHT antioxidant was added to the sample. The sample was dissolved at 140℃, and data were collected. 13 C-NMR, test temperature 125℃, probe size 10 mm, 90° pulse, sampling time AQ is 5 seconds, delay time D1 is 1 second, number of scans 6000.

[0260] (15) Surface energy of thin film: determined according to the method specified in GB / T 14216-2008.

[0261] (16) Comonomer content of propylene-grafted polymers in copolymerized polypropylene: The comonomer content was determined by quantitative Fourier transform infrared (FTIR) spectroscopy. The correlation of the determined comonomer content was calibrated by quantitative nuclear magnetic resonance (NMR) spectroscopy. 13 The calibration method for the C-NMR spectrometer results was performed according to conventional methods in the art.

[0262] (17) Xylene-soluble content, soluble copolymer monomer content, and intrinsic viscosity ratio of soluble content to copolymer polypropylene in propylene-grafted polymers: These were tested using a PolymerCharts CRYST-EX instrument. Trichlorobenzene solvent was used, and the mixture was heated to 150°C, held at that temperature for 90 min, and then sampled for testing. The temperature was then lowered to 35°C, held at that temperature for 70 min, and then sampled for testing again.

[0263] (18) Weight-average molecular weight of copolymer polypropylene in propylene-grafted polymers: determined by high-temperature GPC using a PL-GPC 220 gel permeation chromatography system from Polymer Laboratory. The sample was dissolved in 1,2,4-trichlorobenzene at a concentration of 1.0 mg / ml. The test temperature was 150℃, and the solution flow rate was 1.0 ml / min. A standard curve was established using the molecular weight of polystyrene as an internal reference, and the molecular weight and molecular weight distribution of the sample were calculated based on the elution time.

[0264] (19) Melting temperature Tm: Differential scanning calorimetry was used to analyze the melting and crystallization processes of the material. The specific operation was as follows: under nitrogen protection, 5-10 mg of sample was measured from 20℃ to 200℃ using a three-stage heating and cooling method. The change in heat flow reflected the melting and crystallization processes of the material, and the melting temperature Tm was calculated.

[0265] (20) Grafting efficiency GE and parameter M1: Place 2-4g of grafted product into a Soxhlet extractor and extract with ethyl acetate (or acetone for alkenyl silane monomers as grafting monomers) for 24 hours to remove unreacted monomers and their homopolymers, and obtain pure grafted product. Dry and weigh the product, and calculate parameter M1 and grafting efficiency GE.

[0266] Parameter M1 represents the total content of structural units derived from the grafted monomers in the propylene graft polymer. The formulas for calculating M1 and GE are as follows:

[0267]

[0268] In the above formulas, w0 is the mass of the PP matrix; w1 is the mass of the grafted product before extraction; w2 is the mass of the grafted product after extraction; and w3 is the total mass of the added grafted monomers.

[0269] The mass content (%) of maleic anhydride was tested and calculated according to the method described in the literature (Zhang Guangping, Solid-phase grafting of maleic anhydride onto polypropylene in a ribbon reactor, China Plastics, February 2002, Vol. 16, No. 2, pp. 69-71). MAH The parameter M2 represents the content of structural units derived from maleic anhydride monomers on the grafted propylene graft polymer. The formula for calculating M2 is as follows:

[0270]

[0271] In the above formulas, w1 is the mass of the grafted product before extraction; w2 is the mass of the grafted product after extraction; %G MAH It refers to the mass content of maleic anhydride.

[0272] (21) Volume resistivity: The volume resistivity shall be determined in accordance with the method specified in GB / T 1410-2006.

[0273] Example A1

[0274] (1) Preparation of propylene polymer composition A for preparing layer a:

[0275] Component a is a homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical Co., Ltd., with a melt flow rate of 3.1 g / 10 min, isotacticity of 98%, and molecular weight distribution Mw / Mn of 4.7); component b is a propylene impact copolymer of grade EP200K (purchased from Zhongsha Petrochemical Co., Ltd., with an ethylene content of 8 wt%, an ethylene-propylene copolymer content of 13 wt%, and a melt flow rate of 3.2 g / 10 min); component c is a polyolefin elastomer of grade 6102 (purchased from ExxonMobil, obtained by copolymerization of propylene and ethylene, with an ethylene structural unit content of 16 wt%). The components obtained above were weighed and mixed according to the specified proportions, wherein the mass fraction Wa of component a was 75 parts by weight, the mass fraction Wb of component b was 10 parts by weight, and the mass fraction Wc of component c was 15 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, and based on a total mass of 100 parts by weight for components a, b, and c, the amount of lubricant added is 0.1 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted and mixed evenly by the screws, the material is extruded, granulated, and dried. Granules of propylene polymer composition A are obtained. The melt mass flow rate (MFR) is measured. A = 3.6g / 10min.

[0276] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0277] Component x is a random propylene copolymer of grade F5006 (purchased from Yanshan Petrochemical, ethylene-propylene-butene terpolymer, melt flow rate of 5.2 g / 10 min); component y is a polyolefin elastomer of grade 6102 (purchased from Exxon). The components prepared above are weighed and mixed according to the ratio, wherein the mass part of component x, Wx, is 75 parts by weight and the mass part of component y, Wy, is 25 parts by weight. Wc:Wy is 3:5. Other operations are the same as in step (1), and finally granules of propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 3.2g / 10min.

[0278] (3) Preparation of composite films:

[0279] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the top surface extruder of the same machine. An inorganic anti-sticking agent (silica, Mizusawa, Japan, brand JC-50, hereinafter the same) is added to the top surface extruder. The weight ratio of the anti-sticking agent to the propylene polymer composition granules is 0.02:1. During the casting process, the temperature of the casting quench roll is set to 30°C, and then the film is wound up to form a composite film consisting of an upper surface layer (layer b) and a core layer (layer a). The film thickness is 50 μm, and the thickness ratio of layer b to layer a is 1:2.

[0280] An atomic force microscope image of the cross-section of the composite film is shown below. Figure 3 As shown in the figure, the black portion represents the rubber phase, which is dispersed, strip-shaped, and arranged parallel to each other. The average transverse dimension of the rubber phase is 56 nm, and the average aspect ratio is 10.3.

[0281] Example A2

[0282] (1) Preparation of propylene polymer composition A for preparing layer a:

[0283] Component a is homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical Co., Ltd., melt flow rate 3.1 g / 10 min, isotacticity 98%, molecular weight distribution Mw / Mn 4.7); component b is propylene impact copolymer of grade M180R (purchased from Shanghai Petrochemical Co., Ltd., ethylene content 11 wt%, ethylene-propylene copolymer content 15 wt%, melt flow rate 2.0 g / 10 min); component c is polyolefin elastomer of grade DF640 (obtained by copolymerization of ethylene and butene, butene structural unit content 32 wt%, purchased from Mitsui Chemicals Co., Ltd.). The above-prepared components were weighed and mixed according to the specified proportions, wherein component a (Wa) had a mass fraction of 65 parts by weight, component b (Wb) had a mass fraction of 30 parts by weight, and component c (Wc) had a mass fraction of 5 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, and based on a total mass of 100 parts by weight for components a, b, and c, the amount of lubricant added is 0.1 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of propylene polymer composition A are obtained. The melt mass flow rate (MFR) is measured. A = 3.2g / 10min.

[0284] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0285] Component x is a random propylene copolymer of grade F500EPS (purchased from Shanghai Petrochemical, ethylene-propylene-butene terpolymer, melt flow rate of 5.3 g / 10 min); component y is a polyolefin elastomer of grade DF640 (purchased from Mitsui Chemicals). The components prepared above were weighed and mixed according to the specified ratio, wherein the mass fraction of component x (Wx) was 90 parts by weight, and the mass fraction of component y (Wy) was 10 parts by weight. The ratio of Wc to Wy was 1:2. Other operations were performed as in step (1), and finally, granules of the propylene polymer composition B were obtained. The melt flow rate (MFR) was measured. B = 5.2g / 10min.

[0286] (3) Preparation of composite films:

[0287] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the upper and lower surface extruders of the multilayer extrusion casting machine. An inorganic anti-sticking agent (silica, as above) is also added to the upper and lower surface extruders. The weight ratio of the anti-sticking agent to the propylene polymer composition granules is 0.02:1. During the casting process, the temperature of the casting quench roll is set to 30°C, and then the film is wound up to form a composite film, which consists of upper and lower surface layers (layer b; layer c has the same composition as layer b) and a core layer (layer a). The film thickness is 50 μm, and the sum of the thicknesses of the upper and lower surface layers is 1:1 to the thickness of the core layer.

[0288] Example A3

[0289] (1) Preparation of propylene polymer composition A for preparing layer a:

[0290] Component a is homopolymer polypropylene of grade FC801 (purchased from Shanghai Petrochemical, melt flow rate 7.8 g / 10 min, isotacticity 98%, molecular weight distribution Mw / Mn 4.8); component b is propylene impact copolymer of grade PPB-M02D (purchased from Maoming Petrochemical, ethylene content 8 wt%, ethylene-propylene copolymer content 10 wt%, ethylene unit content in room temperature xylene solubles 36.3 wt%, ethylene unit group [EEE] content 18.5 wt%, melt flow rate 1.5 g / 10 min); component c is polyolefin elastomer of grade EXACT3139 (obtained by copolymerization of ethylene and octene, octene structural unit content 14 wt%, purchased from Exxon). The components obtained above were weighed and mixed according to the specified proportions, where component a (Wa) had a mass fraction of 55 parts by weight, component b (Wb) had a mass fraction of 25 parts by weight, and component c (Wc) had a mass fraction of 20 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, with a molecular weight of 10,000, and based on a total mass fraction of 100 parts by weight for components a, b, and c, the amount of lubricant added was 0.1 parts by weight). The mixture was then added to a high-speed mixer and mixed thoroughly. The mixed material was then fed into the feeder of a twin-screw extruder manufactured by W&P. The material entered the twin screws through the feeder. During processing, the screw temperature was maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of the propylene polymer composition A were obtained. The melt mass flow rate (MFR) was measured. A = 6.6g / 10min.

[0291] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0292] Component x is a random propylene copolymer of brand name F800EPS (purchased from Shanghai Petrochemical, it is an ethylene-propylene-butene terpolymer with a melt flow rate of 8.2 g / 10 min); component y is a polyolefin elastomer of brand name EXACT3139 (purchased from Exxon). The components prepared above are weighed and mixed according to the ratio, wherein the mass part of component x, Wx, is 80 parts by weight and the mass part of component y, Wy, is 20 parts by weight. Wc:Wy is 1:1. Other operations are the same as in step (1), and finally, granules of propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 7.9g / 10min.

[0293] (3) Preparation of composite films:

[0294] The preparation process is the same as step (3) of Example A1.

[0295] Example A4

[0296] (1) Preparation of propylene polymer composition A for preparing layer a:

[0297] The procedure is the same as step (1) of Example A1, except that the mass fraction Wa of component a is 80 parts by weight, the mass fraction Wb of component b is 18 parts by weight, and the mass fraction Wc of component c is 2 parts by weight. Finally, granules of propylene polymer composition A are obtained, and their melt mass flow rate (MFR) is measured. A = 2.8g / 10min.

[0298] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0299] The procedure is the same as step (2) in Example A1, except that the mass fraction of component x, Wx, is 92 parts by weight, and the mass fraction of component y, Wy, is 8 parts by weight. The ratio of Wc to Wy is 1:4. Finally, granules of the propylene polymer composition B are obtained, and their melt flow rate (MFR) is measured. B = 7.7g / 10min.

[0300] (3) Preparation of composite films:

[0301] The procedure is the same as step (3) in Example A1. The film thickness is 50 μm, wherein the thickness ratio of layer b to layer a is 1:3.

[0302] Example A5

[0303] (1) Preparation of propylene polymer composition A for preparing layer a:

[0304] The procedure is the same as step (1) of Example A3, except that the mass fraction Wa of component a is 90 parts by weight, the mass fraction Wb of component b is 5 parts by weight, and the mass fraction Wc of component c is 5 parts by weight. Granules of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 9.6g / 10min.

[0305] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0306] The procedure is the same as step (2) in Example A3, wherein the mass fraction of component x, Wx, is 80 parts by weight, and the mass fraction of component y, Wy, is 20 parts by weight. The ratio of Wc to Wy is 1:4. Finally, granules of the propylene polymer composition B are obtained, and their melt flow rate (MFR) is measured. B = 7.9g / 10min.

[0307] (3) Preparation of composite films:

[0308] The procedure is the same as step (3) in Example A2. The film thickness is 50 μm, wherein the sum of the thicknesses of the upper and lower surface layers is 2:1 to the thickness of the core layer.

[0309] Example A6

[0310] (1) Preparation of propylene polymer composition A for preparing layer a:

[0311] The procedure is the same as step (1) of Example A3, except that the mass fraction Wa of component a is 50 parts by weight, the mass fraction Wb of component b is 40 parts by weight, and the mass fraction Wc of component c is 10 parts by weight. Granules of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 4.6g / 10min.

[0312] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0313] The procedure is the same as step (2) of Example A3, except that the mass fraction of component x, Wx, is 60 parts by weight, and the mass fraction of component y, Wy, is 40 parts by weight. The ratio of Wc to Wy is 1:4. Finally, granules of the propylene polymer composition B are obtained, and their melt flow rate (MFR) is measured. B = 9.8g / 10min.

[0314] (3) Preparation of composite films:

[0315] The procedure is the same as step (3) in Example A3. The film thickness is 50 μm, wherein the ratio of the thickness of the upper surface layer to the thickness of the core layer is 1:4.

[0316] Example A7

[0317] (1) Preparation of propylene polymer composition A for preparing layer a:

[0318] The procedure is the same as step (1) of Example A1, except that the mass fraction Wa of component a is 50 parts by weight, the mass fraction Wb of component b is 20 parts by weight, and the mass fraction Wc of component c is 30 parts by weight. Granules of propylene polymer composition A are obtained, and their melt mass flow rate (MFR) is measured. A = 2.2g / 10min.

[0319] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0320] The procedure is the same as step (2) of Example A1, except that the mass fraction of component x, Wx, is 85 parts by weight, and the mass fraction of component y, Wy, is 15 parts by weight. The ratio of Wc to Wy is 2:1. Finally, granules of the propylene polymer composition B are obtained, and their melt flow rate (MFR) is measured. B = 4.5g / 10min.

[0321] (3) Preparation of composite films:

[0322] The procedure is the same as step (3) in Example A1. The film thickness is 50 μm, wherein the thickness ratio of layer b to layer a is 1:3.

[0323] Example A8

[0324] The composite film was prepared according to the method of Example A1, except that in the preparation of the propylene polymer composition A, the mass fraction of component a (Wa) was 40 parts by weight, the mass fraction of component b (Wb) was 40 parts by weight, and the mass fraction of component c (Wc) was 20 parts by weight. The ratio of Wc to Wy was 4:5. Granules of the propylene polymer composition A were obtained, and their melt flow rate (MFR) was measured. A = 2.8g / 10min.

[0325] Example A9

[0326] The composite film was prepared according to the method of Example A1, except that in the preparation of the propylene polymer composition A, the mass fraction of component a (Wa) was 50 parts by weight, the mass fraction of component b (Wb) was 45 parts by weight, and the mass fraction of component c (Wc) was 5 parts by weight. The ratio of Wc to Wy was 1:5. Granules of the propylene polymer composition A were obtained, and their melt flow rate (MFR) was measured. A = 3.1g / 10min.

[0327] Example A10

[0328] The composite film was prepared according to the method of Example A1. However, in the preparation of the propylene polymer composition A, the mass fraction Wa of component a was 50 parts by weight, the mass fraction Wb of component b was 10 parts by weight, and the mass fraction Wc of component c was 40 parts by weight. The Wc:Wy ratio was 8:5. Granules of the propylene polymer composition A were obtained, and their melt flow rate (MFR) was measured. A = 2.7g / 10min.

[0329] Example A11

[0330] The composite film was prepared according to the method of Example A1. However, in the preparation of the propylene polymer composition B, the mass fraction of component x (Wx) was 50 parts by weight, and the mass fraction of component y (Wy) was 50 parts by weight. The ratio of Wc to Wy was 3:10. Granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 4.7g / 10min.

[0331] Example A12

[0332] The composite film was prepared according to the method of Example A1. However, the propylene polymer composition B contained only component x.

[0333] Example A13

[0334] The composite film was prepared according to the method of Example A1. However, in the preparation of the propylene polymer composition B, the mass fraction of component x (Wx) was 92.5 parts by weight, and the mass fraction of component y (Wy) was 7.5 parts by weight. The ratio of Wc to Wy was 2:1. Finally, granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 5.5g / 10min.

[0335] Example A14

[0336] The composite film was prepared according to the method of Example A1. However, in the preparation of the propylene polymer composition B, the mass fraction of component x (Wx) was 85 parts by weight, and the mass fraction of component y (Wy) was 15 parts by weight. The ratio of Wc to Wy was 1:1. Finally, granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 5.1g / 10min.

[0337] Example A15

[0338] The composite film was prepared according to the method of Example A1. However, in the preparation of the propylene polymer composition B, the mass fraction of component x (Wx) was 70 parts by weight, and the mass fraction of component y (Wy) was 30 parts by weight. The ratio of Wc to Wy was 1:2. Finally, granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured.B = 4.4g / 10min.

[0339] Example A16

[0340] The composite film was prepared according to the method of Example A1. However, in the preparation of the propylene polymer composition B, the mass fraction of component x (Wx) was 40 parts by weight, and the mass fraction of component y (Wy) was 60 parts by weight. The ratio of Wc to Wy was 1:4. Finally, granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 2.9g / 10min.

[0341] Example A17

[0342] The composite film was prepared according to the method of Example A1, except that in the preparation of the propylene polymer composition B, the mass fraction of component x, Wx, was 97 parts by weight, and the mass fraction of component y, Wy, was 3 parts by weight. The ratio of Wc to Wy was 5:1. Finally, granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 6.0g / 10min.

[0343] Comparative Example A1

[0344] A composite film was prepared according to the procedure in Example A1, except that only propylene polymer composition A was used for extrusion casting into a single-layer film with a thickness of 50 μm.

[0345] Comparative Example A2

[0346] The composite film was prepared according to the procedure in Example A2, except that only the propylene polymer composition B was used for extrusion casting into a single-layer film with a thickness of 50 μm.

[0347] Comparative Example A3

[0348] The composite film was prepared according to the procedure in Example A1, except that the propylene polymer composition A contained only component b. Figure 4 As shown, according to AFM observation, the average transverse dimension of the rubber phase is 380 nm, and the average aspect ratio is 23.4.

[0349] Comparative Example A4

[0350] The composite film was prepared according to the procedure of Example A1, except that the propylene polymer composition A contained only component a and component b, wherein the mass part Wa of component a was 75 parts by weight and the mass part Wb of component b was 25 parts by weight.

[0351] Comparative Example A5

[0352] The composite film was prepared according to the procedure of Example A1, except that the propylene polymer composition A contained only component a and component c, wherein the mass part Wa of component a was 75 parts by weight and the mass part Wc of component c was 25 parts by weight.

[0353] Table 1

[0354]

[0355] The results in Table 1 show that the composite film according to the present invention can simultaneously possess excellent impact resistance and optical properties, and even excellent tensile strength and heat-sealing strength. Compared with single-layer films or composite films not based on the present invention, the composite film of the present invention can achieve a better balance of the above-mentioned properties, and exhibits better stability and thickness uniformity during extrusion casting.

[0356] Example B1

[0357] (1) Preparation of propylene polymer composition A for preparing layer a:

[0358] Component a is a homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical Co., Ltd., with a melt flow rate of 3.1 g / 10 min, isotacticity of 98%, and molecular weight distribution Mw / Mn of 4.7); component b is a polyolefin elastomer of grade 6102 (purchased from ExxonMobil). The components obtained above were weighed and mixed according to the specified proportions, wherein the mass fraction Wa of component a was 80 parts by weight and the mass fraction Wb of component b was 20 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, and based on a total mass of 100 parts by weight for components a and b, the amount of lubricant added is 0.1 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of propylene polymer composition A are obtained. The melt mass flow rate (MFR) is measured. A = 3.5g / 10min.

[0359] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0360] Component x is a random propylene copolymer of grade F5006 (purchased from Yanshan Petrochemical, ethylene-propylene-butene terpolymer, melt flow rate of 5.2 g / 10 min); component y is a polyolefin elastomer of grade 6102 (purchased from ExxonMobil); component z is a propylene impact copolymer of grade EP200K (purchased from Zhongsha Petrochemical, ethylene content of 8 wt%, ethylene-propylene copolymer content of 13 wt%, melt flow rate of 3.2 g / 10 min). The components prepared above were weighed and mixed according to the ratio, wherein the mass fraction of component x Wx was 85 parts by weight, the mass fraction of component y Wy was 5 parts by weight, and the mass fraction of component z Wz was 10 parts by weight. Wb:Wy was 4:1. Other operations were the same as in step (1), and finally, granules of propylene polymer composition B were obtained. The melt flow rate (MFR) was measured. B = 4.7g / 10min.

[0361] (3) Preparation of composite films:

[0362] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the top surface extruder of the same machine. An inorganic anti-sticking agent (silica, as above) is also added to the top surface extruder. The weight ratio of the anti-sticking agent to the propylene polymer composition granules is 0.02:1. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film consisting of an upper surface layer (layer b) and a core layer (layer a). The film thickness is 50 μm, and the thickness ratio of layer b to layer a is 1:2.

[0363] Example B2

[0364] (1) Preparation of propylene polymer composition A for preparing layer a:

[0365] Component a is a propylene impact copolymer of grade M180R (purchased from Shanghai Petrochemical, with an ethylene content of 11% by weight, an ethylene-propylene copolymer content of 15% by weight, and a melt flow rate of 2.0 g / 10 min); component b is a polyolefin elastomer of grade DF640 (purchased from Mitsui Chemicals). The components prepared above were weighed and mixed according to the specified proportions, wherein the mass fraction Wa of component a was 95 parts by weight and the mass fraction Wb of component b was 5 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, and based on a total mass of 100 parts by weight for components a and b, the amount of lubricant added is 0.1 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of propylene polymer composition A are obtained. The melt mass flow rate (MFR) is measured. A = 3.1g / 10min.

[0366] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0367] Component x is a random propylene copolymer of brand name F500EPS (purchased from Shanghai Petrochemical, ethylene-propylene-butene terpolymer, melt flow rate of 5.3 g / 10 min); component y is a polyolefin elastomer of brand name DF640 (purchased from Mitsui); component z is a propylene impact copolymer of brand name M180R (purchased from Shanghai Petrochemical, ethylene content of 11 wt%, ethylene-propylene copolymer content of 15 wt%, melt flow rate of 2.0 g / 10 min). The components prepared above were weighed and mixed according to the ratio, wherein the mass fraction of component x Wx was 60 parts by weight, the mass fraction of component y Wy was 20 parts by weight, and the mass fraction of component z Wz was 20 parts by weight. Wb:Wy was 1:4. Other operations were the same as in step (1), and finally, granules of propylene polymer composition B were obtained. The melt flow rate (MFR) was measured. B = 4.4g / 10min.

[0368] (3) Preparation of composite films:

[0369] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the upper and lower surface extruders of the multilayer extrusion casting machine. An inorganic anti-sticking agent (silica, as above) is also added to the upper and lower surface extruders. The weight ratio of the anti-sticking agent to the propylene polymer composition granules is 0.02:1. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film, which consists of upper and lower surface layers (layer b; layer c has the same composition as layer b) and a core layer (layer a). The film thickness is 50 μm, and the thickness ratio of the upper and lower surface layers to the core layer is 1:1.

[0370] Example B3

[0371] (1) Preparation of propylene polymer composition A for preparing layer a:

[0372] Component a is homopolymer polypropylene of grade FC801 (purchased from Shanghai Petrochemical, melt flow rate 7.8 g / 10 min, isotacticity 98%, molecular weight distribution Mw / Mn 4.8); component b is polyolefin elastomer of grade EXACT3139 (purchased from Exxon). The components prepared above were weighed and mixed according to the specified proportions, wherein component a (W) had a mass fraction Wa of 85 parts by weight and component b (Wb) had a mass fraction Wb of 15 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, and based on a total mass of 100 parts by weight for components a and b, the amount of lubricant added is 0.1 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of propylene polymer composition A are obtained. The melt mass flow rate (MFR) is measured. A = 7.9g / 10min.

[0373] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0374] Component x is a random propylene copolymer of grade F800EPS (purchased from Shanghai Petrochemical); component y is a polyolefin elastomer of grade EXACT3139 (purchased from ExxonMobil); and component z is a polypropylene impact copolymer of grade PPB-M02D (purchased from Maoming Petrochemical). The components obtained above were weighed and mixed according to the specified ratio, where component x (Wx) had a mass fraction of 85 parts by weight, component y (Wy) had a mass fraction of 10 parts by weight, and component z (Wz) had a mass fraction of 5 parts by weight. The ratio of Wb to Wy was 3:2. Other operations were performed as in step (1), and finally, granules of the propylene polymer composition B were obtained. The melt flow rate (MFR) was measured. B = 7.4g / 10min.

[0375] (3) Preparation of composite films:

[0376] The preparation process is the same as step (3) of Example B1.

[0377] Example B4

[0378] (1) Preparation of propylene polymer composition A for preparing layer a:

[0379] The procedure is the same as step (1) of Example B1, except that the mass fraction Wa of component a is 70 parts by weight and the mass fraction Wb of component b is 30 parts by weight. Granules of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 3.2g / 10min.

[0380] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0381] The operation is the same as step (2) of Example B1, except that the mass fraction of component x, Wx, is 90 parts by weight, the mass fraction of component y, Wy, is 5 parts by weight, and the mass fraction of component z, Wz, is 5 parts by weight. The ratio of Wb to Wy is 6:1. Other operations are the same as in step (1), and finally, granules of propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 8.2g / 10min.

[0382] (3) Preparation of composite films:

[0383] The procedure is the same as step (3) in Example B1. The film thickness is 50 μm, wherein the thickness ratio of layer b to layer a is 1:3.

[0384] Example B5

[0385] (1) Preparation of propylene polymer composition A for preparing layer a:

[0386] The procedure is the same as step (1) in Example B3, except that the mass fraction Wa of component a is 75 parts by weight and the mass fraction Wb of component b is 25 parts by weight. Granules of propylene polymer composition A are obtained, and their melt mass flow rate (MFR) is measured. A = 9.3g / 10min.

[0387] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0388] The procedure is the same as step (2) of Example B3, except that the mass fraction of component x, Wx, is 85 parts by weight, the mass fraction of component y, Wy, is 13 parts by weight, and the mass fraction of component z, Wz, is 2 parts by weight. The ratio of Wb to Wy is 25:13. Finally, granules of the propylene polymer composition B are obtained, and their melt flow rate (MFR) is measured. B = 9.2g / 10min.

[0389] (3) Preparation of composite films:

[0390] The operation is the same as step (3) in Example B2. The film thickness is 50 μm, wherein the sum of the thicknesses of the upper and lower surface layers is 2:1 to the thickness of the core layer.

[0391] Example B6

[0392] (1) Preparation of propylene polymer composition A for preparing layer a:

[0393] The procedure is the same as step (1) in Example B3, except that the mass fraction Wa of component a is 100 parts by weight. Granules of propylene polymer composition A are obtained, and their melt mass flow rate (MFR) is measured. A = 7.8g / 10min.

[0394] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0395] The procedure is the same as step (2) of Example B3, except that the mass fraction of component x, Wx, is 50 parts by weight, the mass fraction of component y, Wy, is 30 parts by weight, and the mass fraction of component z, Wz, is 20 parts by weight. Finally, granules of the propylene polymer composition B are obtained, and their melt flow rate (MFR) is measured. B = 6.8g / 10min.

[0396] (3) Preparation of composite films:

[0397] The procedure is the same as step (3) in Example B3. The film thickness is 50 μm, wherein the ratio of the thickness of the upper surface layer to the thickness of the core layer is 1:4.

[0398] Example B7

[0399] (1) Preparation of propylene polymer composition A for preparing layer a:

[0400] The procedure is the same as step (1) of Example B1. The mass fraction of component a, Wa, is 100 parts by weight. Granules of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 3.1g / 10min.

[0401] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0402] The operation is the same as step (2) of Example B1, except that the mass fraction of component x, Wx, is 50 parts by weight, the mass fraction of component y, Wy, is 20 parts by weight, and the mass fraction of component z, Wz, is 30 parts by weight. Other operations are the same as in step (1), and finally, granules of the propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 3.5g / 10min.

[0403] (3) Preparation of composite films:

[0404] The procedure is the same as step (3) in Example B1. The film thickness is 50 μm, wherein the thickness ratio of layer b to layer a is 1:3.

[0405] Example B8

[0406] The composite film was prepared according to the method of Example B1, except that in the preparation of propylene polymer composition A, the mass fraction Wa of component a was 100 parts by weight. Finally, granules of propylene polymer composition A were obtained, and their melt mass flow rate (MFR) was measured. A = 3.1g / 10min.

[0407] Example B9

[0408] The composite film was prepared according to the method of Example B1, except that in the preparation of the propylene polymer composition A, the mass fraction of component a, Wa, was 50 parts by weight, and the mass fraction of component b, Wb, was 50 parts by weight. The Wb:Wy ratio was 10:1. Finally, granules of the propylene polymer composition A were obtained, and their melt flow rate (MFR) was measured. A = 3.5g / 10min.

[0409] Example B10

[0410] The composite film was prepared according to the method of Example B1, except that in the preparation of the propylene polymer composition B, the mass fraction of component x (Wx) was 40 parts by weight, the mass fraction of component y (Wy) was 30 parts by weight, and the mass fraction of component z (Wz) was 30 parts by weight. The ratio of Wb to Wy was 2:3. Granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 4.5g / 10min.

[0411] Example B11

[0412] The composite film was prepared according to the method of Example B1, except that in the preparation of the propylene polymer composition B, the mass fraction of component x (Wx) was 50 parts by weight, the mass fraction of component y (Wy) was 40 parts by weight, and the mass fraction of component z (Wz) was 10 parts by weight. The ratio of Wb to Wy was 1:2. Granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 5.0g / 10min.

[0413] Example B12

[0414] The composite film was prepared according to the method of Example B1. However, in the preparation of the propylene polymer composition B, the mass fraction of component x (Wx) was 50 parts by weight, the mass fraction of component y (Wy) was 10 parts by weight, and the mass fraction of component z (Wz) was 40 parts by weight. The ratio of Wb to Wy was 2:1. Granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 4.8g / 10min.

[0415] Example B13

[0416] The composite film was prepared according to the method of Example B1, except that in the preparation of the propylene polymer composition A, the mass fraction of component a, Wa, was 99 parts by weight, and the mass fraction of component b, Wb, was 1 part by weight. The ratio of Wb to Wy was 1:5. Finally, granules of the propylene polymer composition A were obtained, and their melt flow rate (MFR) was measured. A = 3.2g / 10min.

[0417] Example B14

[0418] The composite film was prepared according to the method of Example B1, except that in the preparation of the propylene polymer composition A, the mass fraction of component a, Wa, was 97.5 parts by weight, and the mass fraction of component b, Wb, was 2.5 parts by weight. The Wb:Wy ratio was 1:2. Finally, granules of the propylene polymer composition A were obtained, and their melt mass flow rate (MFR) was measured. A = 3.1g / 10min.

[0419] Example B15

[0420] The composite film was prepared according to the method of Example B1, except that in the preparation of the propylene polymer composition A, the mass fraction of component a, Wa, was 95 parts by weight, and the mass fraction of component b, Wb, was 5 parts by weight. The Wb:Wy ratio was 1:1. Finally, granules of the propylene polymer composition A were obtained, and their melt flow rate (MFR) was measured. A = 3.2g / 10min.

[0421] Example B16

[0422] The composite film was prepared according to the method of Example B1. However, in the preparation of the propylene polymer composition A, the mass fraction Wa of component a was 90 parts by weight, and the mass fraction Wb of component b was 10 parts by weight. The Wb:Wy ratio was 2:1. Finally, granules of the propylene polymer composition A were obtained, and their melt flow rate (MFR) was measured. A = 3.3g / 10min.

[0423] Example B17

[0424] The composite film was prepared according to the method of Example B1, except that in the preparation of the propylene polymer composition A, the mass fraction of component a, Wa, was 75 parts by weight, and the mass fraction of component b, Wb, was 25 parts by weight. The Wb:Wy ratio was 5:1. Finally, granules of the propylene polymer composition A were obtained, and their melt flow rate (MFR) was measured. A = 3.1g / 10min.

[0425] Comparative Example B1

[0426] The composite film was prepared according to the method of Example B1, except that only propylene polymer composition A was used for extrusion casting into a single-layer film with a film thickness of 50 μm.

[0427] Comparative Example B2

[0428] The composite film was prepared according to the method of Example B2, except that only the propylene polymer composition B was used for extrusion casting into a single-layer film with a thickness of 50 μm.

[0429] Comparative Example B3

[0430] The composite film was prepared according to the method of Example B1, except that the propylene polymer composition B contained only component x.

[0431] Comparative Example B4

[0432] The composite film was prepared according to the method of Example B1, except that the propylene polymer composition B contained only component x and component y, wherein the mass fraction Wx of component x was 85 parts by weight and the mass fraction Wy of component y was 15 parts by weight.

[0433] Example B18

[0434] The composite film was prepared according to the method of Example B2, except that the propylene polymer composition B contained only component x and component z, wherein the mass fraction Wx of component x was 70 parts by weight and the mass fraction Wz of component z was 30 parts by weight.

[0435] Table 2

[0436]

[0437] The results in Table 2 show that the composite film according to the present invention possesses excellent impact resistance and optical properties, and even excellent tensile properties and heat-sealing strength. Compared with single-layer films or composite films not based on the present invention, the composite film of the present invention achieves a good balance of various properties, and exhibits better stability and thickness uniformity during extrusion casting.

[0438] Example C1

[0439] The operation of Example A1 is basically repeated, except that the polyolefin elastomer used in steps (1) and (2) is replaced with a polyolefin elastomer of grade 8200 (purchased from Dow Chemical Company, which is an ethylene-1-octene copolymer with an octene structural unit content of 38% by weight). This polyolefin elastomer is tested at 230°C and a shear rate of 160 s. -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 2.18, and the elastomer is tested at 230°C and a shear rate of 640 s. -1 The shear viscosity η 640 The weight ratio of the anti-sticking agent to the propylene polymer composition granules in step (3) is 0.2:100. The melt mass flow rate (MFR) is 185 Pa·s. A =3.8g / 10min, MFR B = 4.2g / 10min.

[0440] An atomic force microscope image of the cross-section of the composite film is shown below. Figure 5 As shown in the figure, the black portion represents the rubber phase, which is dispersed, strip-shaped, and arranged parallel to each other. The average transverse dimension of the rubber phase is 84 nm, and the average aspect ratio is 8.8.

[0441] Example C2

[0442] The operation of Example A2 is basically repeated, except that the polyolefin elastomer used in steps (1) and (2) is replaced with DF840 polyolefin elastomer (purchased from Mitsui Chemicals, an ethylene-1-butene copolymer with a butene structural unit content of 25% by weight). This polyolefin elastomer is tested at 230°C and a shear rate of 160 s. -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 1.75, and the elastomer is at 230℃ and a shear rate of 640s. -1 The shear viscosity η 640 The weight ratio of the anti-sticking agent to the propylene polymer composition granules in step (3) is 0.2:100. The melt mass flow rate (MFR) is 398 Pa·s. A = 3.4g / 10min, MFR B = 5.6g / 10min.

[0443] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 105 nm, and the average aspect ratio was 8.5.

[0444] Example C3

[0445] (1) Preparation of propylene polymer composition A for preparing layer a:

[0446] Component a is homopolymer polypropylene of grade FC801 (purchased from Shanghai Petrochemical, melt flow rate 7.8 g / 10 min, isotacticity 98%, molecular weight distribution Mw / Mn 4.8); component b is propylene impact copolymer of grade PPB-M02D (purchased from Maoming Petrochemical, ethylene content 8 wt%, ethylene-propylene copolymer content 10 wt%, ethylene unit content in xylene solubles at room temperature 36.3 wt%, ethylene unit group [EEE] content 18.5 wt%, melt flow rate 1.5 g / 10 min); component c is polyolefin elastomer of grade VM3980 (purchased from Exxon, propylene-ethylene copolymer, ethylene structural unit content 9 wt%, this polyolefin elastomer at 230℃ and shear rate 160 s). -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 2.26, and the elastomer is at 230°C and a shear rate of 640 s. -1 The shear viscosity η 640The concentration is 205 Pa·s. The components obtained above are weighed and mixed according to the specified ratio, where component a (Wa) has 55 parts by weight, component b (Wb) has 25 parts by weight, and component c (Wc) has 20 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant, Switzerland, molecular weight 10000, with 0.1 parts by weight based on the sum of the masses of components a, b, and c being 100 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried by the screws, granules of the propylene polymer composition A are obtained. The melt mass flow rate (MFR) is measured. A = 7.0g / 10min.

[0447] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0448] Component x is a random propylene copolymer of grade F800EDF (purchased from Shanghai Petrochemical, a propylene-ethylene binary copolymer with a melt flow rate of 7.8 g / 10 min); component y is a polyolefin elastomer of grade VM3980 (purchased from ExxonMobil, a propylene-ethylene copolymer with an ethylene structural unit content of 9% by weight; this polyolefin elastomer is suitable for use at 230°C and a shear rate of 160 s). -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 2.26, and the elastomer is at 230℃ and a shear rate of 640s. -1 The shear viscosity η 640 The concentration is 205 Pa·s. The components prepared above are weighed and mixed according to the specified ratio, wherein component x has a mass fraction Wx of 80 parts by weight and component y has a mass fraction Wy of 20 parts by weight. Other operations are the same as in step (1), and finally, granules of the propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 8.3g / 10min.

[0449] (3) Preparation of composite films:

[0450] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the upper and lower surface extruders of the multilayer extrusion casting machine. Inorganic anti-sticking agent (silica, as above) is added to the upper and lower surface extruders. The weight ratio of anti-sticking agent to propylene polymer composition granules is 0.2:100. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film, which consists of upper and lower surface layers (layer b; layer c has the same composition as layer b) and a core layer (layer a). The film thickness is 50 μm, and the sum of the thicknesses of the upper and lower surface layers is 1:4 of the thickness of the core layer.

[0451] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 88 nm, and the average aspect ratio was 9.6.

[0452] Example C4

[0453] (1) Preparation of propylene polymer composition A for preparing layer a:

[0454] The procedure is the same as step (1) of Example C1, except that the mass fraction Wa of component a is 80 parts by weight, the mass fraction Wb of component b is 18 parts by weight, and the mass fraction Wc of component c is 2 parts by weight. Component c is a polyolefin elastomer of grade 8411 (purchased from Dow Chemical, an ethylene-1-octene copolymer with an octene structural unit content of 36% by weight). This polyolefin elastomer is tested at 230°C and a shear rate of 160 s. -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 1.80, and the elastomer is at 230℃ and a shear rate of 640s. -1 The shear viscosity η 640 The granules of propylene polymer composition A were obtained, and their melt mass flow rate (MFR) was measured to be 148 Pa·s. A = 2.6g / 10min.

[0455] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0456] The procedure is the same as step (2) of Example C1, except that the mass fraction of component x, Wx, is 92 parts by weight and the mass fraction of component y, Wy, is 8 parts by weight. Other procedures are the same as in step (1), and finally, granules of the propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 7.5g / 10min.

[0457] (3) Preparation of composite films:

[0458] The procedure is the same as step (3) of Example C1. The film thickness is 50 μm, wherein the thickness ratio of layer b to layer a is 1:6.

[0459] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the horizontal axis of the rubber phase was 196 nm, and the average aspect ratio was 5.3.

[0460] Example C5

[0461] (1) Preparation of propylene polymer composition A for preparing layer a:

[0462] The procedure is the same as step (1) of Example C1, except that the mass fraction Wa of component a is 90 parts by weight, the mass fraction Wb of component b is 5 parts by weight, and the mass fraction Wc of component c is 5 parts by weight. Granules of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 3.0g / 10min.

[0463] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0464] The procedure is the same as step (2) of Example C1, except that the mass fraction of component x, Wx, is 80 parts by weight and the mass fraction of component y, Wy, is 20 parts by weight. Finally, granules of the propylene polymer composition B are obtained, and their melt flow rate (MFR) is measured. B = 3.5g / 10min.

[0465] (3) Preparation of composite films:

[0466] The operation is the same as step (3) of Example C2. The film thickness is 50 μm, wherein the sum of the thicknesses of the upper and lower surface layers is 2:1 to the thickness of the core layer.

[0467] Example C6

[0468] (1) Preparation of propylene polymer composition A for preparing layer a:

[0469] The procedure is the same as step (1) of Example C3, except that the mass fraction Wa of component a is 50 parts by weight, the mass fraction Wb of component b is 40 parts by weight, and the mass fraction Wc of component c is 10 parts by weight. Granules of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 4.8g / 10min.

[0470] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0471] The procedure is the same as step (2) of Example C3, except that the mass fraction Wx of component x is 60 parts by weight and the mass fraction Wy of component y is 40 parts by weight. Finally, granules of the propylene polymer composition B are obtained, and their melt flow rate (MFR) is measured. B = 9.6g / 10min.

[0472] (3) Preparation of composite film: The operation is the same as step (3) in Example C3.

[0473] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average dimension of the horizontal axis of the rubber phase was 23 nm, and the average aspect ratio was 19.8.

[0474] Example C7

[0475] (1) Preparation of propylene polymer composition A for preparing layer a:

[0476] The procedure is the same as in Example C1, except that the mass fraction Wa of component a is 50 parts by weight, the mass fraction Wb of component b is 20 parts by weight, and the mass fraction Wc of component c is 30 parts by weight. Granules of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 2.0g / 10min.

[0477] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0478] The procedure is the same as step (2) of Example C1, except that the mass fraction of component x, Wx, is 85 parts by weight and the mass fraction of component y, Wy, is 15 parts by weight. Other procedures are the same as in step (1), and finally, granules of the propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 4.3g / 10min.

[0479] (3) Preparation of composite films:

[0480] The operation is the same as in Example C1. The film thickness is 50 μm, wherein the thickness ratio of layer b to layer a is 1:3.

[0481] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the horizontal axis of the rubber phase was 145 nm, and the average aspect ratio was 12.1.

[0482] Example C8

[0483] A propylene polymer film was prepared according to the method of Example C1. The difference was that in the preparation of propylene polymer composition A, the mass fraction Wa of component a was 40 parts by weight, the mass fraction Wb of component b was 40 parts by weight, and the mass fraction Wc of component c was 20 parts by weight. Granules of propylene polymer composition A were obtained, and their melt flow rate (MFR) was measured. A = 3.1g / 10min.

[0484] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average dimension of the rubber phases along the horizontal axis was 88 nm, and the average aspect ratio was 17.0.

[0485] Example C9

[0486] A propylene polymer film was prepared according to the method of Example C1, except that in the preparation of propylene polymer composition B, the mass fraction of component x, Wx, was 95 parts by weight, and the mass fraction of component y, Wy, was 5 parts by weight. Finally, granules of propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 5.5g / 10min.

[0487] Example C10

[0488] A propylene polymer film was prepared according to the method of Example C1, except that in the preparation of propylene polymer composition B, the mass fraction of component x (Wx) was 70 parts by weight, and the mass fraction of component y (Wy) was 30 parts by weight. Finally, granules of propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 4.7g / 10min.

[0489] Example C11

[0490] A propylene polymer film was prepared according to the method of Example C1, except that in the preparation of propylene polymer composition B, the mass fraction of component x, Wx, was 40 parts by weight, and the mass fraction of component y, Wy, was 60 parts by weight. Finally, granules of propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 3.2g / 10min.

[0491] Example C12

[0492] Propylene polymer composition A was prepared according to the method of Example C3, and propylene polymer composition B was prepared according to the method of Example C2, such that (ηA) 160 -ηB 160 ) and (ηA 640 -ηB 640 All values ​​are less than 0. The composite film was prepared according to the method in Example C3.

[0493] Comparative Example C1

[0494] Propylene polymer films were prepared according to the method of Example C1, except that in the preparation of propylene polymer composition A, polyolefin elastomer c was replaced with polyolefin elastomer of grade DF740 (purchased from Mitsui Chemicals, with a butene structural unit content of 28% by weight). This polyolefin elastomer was tested at 230°C and a shear rate of 160 s. -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 1.63, and the elastomer is at 230℃ and a shear rate of 640s. -1 The shear viscosity η 640 The final product was propylene polymer composition A granules, and its melt mass flow rate (MFR) was measured to be 554 Pa·s. A = 2.4g / 10min.

[0495] Comparative Example C2

[0496] The propylene polymer film was prepared according to the method of Example C2, except that in the preparation of the propylene polymer composition B, the polyolefin elastomer y was replaced with a polyolefin elastomer of grade 8400 (purchased from Dow Chemical Company, propylene-octene copolymer, octene structural unit content of 35%). This polyolefin elastomer was tested at 230°C and a shear rate of 160 s. -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 2.45, and the elastomer is at 230℃ and a shear rate of 640s. -1 The shear viscosity η 640 The final product was propylene polymer composition B granules, and its melt mass flow rate (MFR) was measured to be 84 Pa·s. B = 8.4g / 10min.

[0497] Comparative Example C3

[0498] The composite film was prepared according to the method of Example C1, except that the propylene polymer composition B contained only component x.

[0499] Comparative Example C4

[0500] The composite film was prepared according to the method of Example C1, except that the propylene polymer composition A contained only component a and component b, wherein the mass part Wa of component a was 75 parts by weight and the mass part Wb of component b was 25 parts by weight.

[0501] Comparative Example C5

[0502] The composite film was prepared according to the method of Example C1, except that the propylene polymer composition A contained only component a and component c, wherein the mass part Wa of component a was 75 parts by weight and the mass part Wc of component c was 25 parts by weight.

[0503] Table 3

[0504]

[0505] Table 4

[0506]

[0507] The results in Tables 3 and 4 show that the composite film according to the present invention has both good impact resistance and optical properties, and even good film uniformity. In particular, when a polyolefin elastomer with a specific shear viscosity is used, the film surface is stable during extrusion casting, and the uniformity of film thickness and impact resistance is greatly improved.

[0508] Example D1

[0509] The operation is basically the same as that in Example B1, except that:

[0510] Replace the polyolefin elastomer used in step (1) with a polyolefin elastomer of brand name 8411 (purchased from Dow Chemical Company, ethylene-1-octene copolymer, octene structural unit content of 36% by weight), which is tested at 230°C and a shear rate of 160s. -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 1.80, and the elastomer is at 230℃ and a shear rate of 640s. -1 The melt mass flow rate (MFR) of the propylene polymer composition A pellets was determined to be at a shear viscosity of 148 Pa·s. A = 3.4g / 10min.

[0511] Replace the polyolefin elastomer used in step (2) with a polyolefin elastomer of grade 8200 (purchased from Dow Chemical Company, ethylene-1-octene copolymer, octene structural unit content of 38% by weight), which is tested at 230°C and a shear rate of 160 s. -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 2.18, and the elastomer is tested at 230°C and a shear rate of 640 s. -1 The shear viscosity η 640 The melt mass flow rate (MFR) of the propylene polymer composition B pellets was 185 Pa·s.B = 4.9g / 10min.

[0512] In step (3), the weight ratio of the anti-sticking agent to the propylene polymer composition granules is 0.2:100.

[0513] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 72 nm, and the average aspect ratio was 5.5.

[0514] Example D2

[0515] The operation of Example B2 is basically repeated, except that the polyolefin elastomer used in steps (1) and (2) is replaced with DF840 polyolefin elastomer (purchased from Mitsui Chemicals, ethylene-1-butene copolymer, butene structural unit content of 25% by weight), which is tested at 230°C and a shear rate of 160 s. -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 1.75, and the elastomer is at 230℃ and a shear rate of 640s. -1 The shear viscosity η 640 The weight ratio of the anti-sticking agent to the propylene polymer composition granules in step (3) is 0.2:100. The melt mass flow rate (MFR) is 398 Pa·s. A =3.3g / 10min, MFR B = 4.5g / 10min.

[0516] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 130 nm, and the average aspect ratio was 6.4.

[0517] Example D3

[0518] (1) Preparation of propylene polymer composition A for preparing layer a

[0519] Component a is homopolymer polypropylene of grade FC801 (purchased from Shanghai Petrochemical, melt flow rate 7.8 g / 10 min, isotacticity 98%, molecular weight distribution Mw / Mn 4.8); component b is polyolefin elastomer of grade VM3980 (purchased from Exxon, propylene-ethylene copolymer, ethylene structural unit content 9% by weight, this polyolefin elastomer at 230℃ and shear rate 160 s). -1 and 640s -1 The ratio of shear viscosity η 160 / η 640The value is 2.26, and the elastomer is at 230℃ and a shear rate of 640s. -1 The shear viscosity is 205 Pa·s. The components prepared above were weighed and mixed according to the specified ratio, where component a (Wa) had a mass fraction of 85 parts by weight and component b (Wb) had a mass fraction of 15 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, with 0.1 parts by weight based on a total mass fraction of 100 parts by weight for components a and b) was added. The mixture was then added to a high-speed mixer and mixed thoroughly. The mixed material was then fed into the feeder of a twin-screw extruder manufactured by W&P. The material entered the twin screws through the feeder. During processing, the screw temperature was maintained between 160-230°C. After melting and mixing evenly by the screws, extrusion, granulation, and drying, granules of the propylene polymer composition A were obtained. The melt mass flow rate (MFR) was measured. A = 7.4g / 10min.

[0520] (2) Preparation of propylene polymer composition B for preparing layer b

[0521] Component x is a propylene random copolymer of grade F800EDF (purchased from Shanghai Petrochemical, an ethylene-propylene binary copolymer with a melt flow rate of 7.8 g / 10 min); component y is a polyolefin elastomer of grade VM3980 (purchased from ExxonMobil, a propylene-ethylene copolymer with an ethylene structural unit content of 9% by weight, this polyolefin elastomer is suitable for use at 230°C and a shear rate of 160 s). -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 2.26, and the elastomer is at 230℃ and a shear rate of 640s. -1 The shear viscosity was 205 Pa·s. Component z was a propylene impact copolymer of brand name PPB-MO2D (purchased from Maoming Petrochemical, with an ethylene content of 8 wt%, an ethylene-propylene copolymer content of 10 wt%, an ethylene unit content of 36.3 wt% in its room temperature xylene solubles, an ethylene unit group [EEE] content of 18.5 wt%, and a melt mass flow rate of 1.5 g / 10 min). The components prepared above were weighed and mixed according to the proportions, wherein the mass fraction of component x, Wx, was 85 parts by weight, the mass fraction of component y, Wy, was 10 parts by weight, and the mass fraction of component z, Wz, was 5 parts by weight. Other operations were the same as in step (1), and finally, granules of propylene polymer composition B were obtained. The melt mass flow rate (MFR) was measured. B = 7.9g / 10min.

[0522] (3) Preparation of composite films

[0523] The preparation process is the same as step (3) of Example D1.

[0524] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the horizontal axis of the rubber phase was 72 nm, and the average aspect ratio was 13.2.

[0525] Example D4

[0526] (1) Preparation of propylene polymer composition A for preparing layer a

[0527] The procedure is the same as step (1) of Example D1, except that the mass fraction Wa of component a is 70 parts by weight and the mass fraction Wb of component b is 30 parts by weight. Granules of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 3.5g / 10min.

[0528] (2) Preparation of propylene polymer composition B for preparing layer b

[0529] The operation is the same as step (2) of Example D1, except that the mass fraction of component x, Wx, is 90 parts by weight, the mass fraction of component y, Wy, is 5 parts by weight, and the mass fraction of component z, Wz, is 5 parts by weight. Other operations are the same as in step (1), and finally, granules of the propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 5.2g / 10min.

[0530] (3) Preparation of composite films:

[0531] The operation is the same as step (3) of Example D1. The film thickness is 50 μm, wherein the thickness ratio of layer b to layer a is 1:3.

[0532] Example D5

[0533] (1) Preparation of propylene polymer composition A for preparing layer a

[0534] The procedure is the same as step (1) in Example D3, except that the mass fraction Wa of component a is 75 parts by weight and the mass fraction Wb of component b is 25 parts by weight. Granules of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 9.0g / 10min.

[0535] (2) Preparation of propylene polymer composition B for preparing layer b

[0536] The procedure is the same as step (2) of Example D3, except that the mass fraction of component x, Wx, is 85 parts by weight, the mass fraction of component y, Wy, is 13 parts by weight, and the mass fraction of component z, Wz, is 2 parts by weight. Finally, granules of the propylene polymer composition B are obtained, and their melt flow rate (MFR) is measured. B = 9.3g / 10min.

[0537] (3) Preparation of composite films:

[0538] The steps are the same as in Example D2. The film thickness is 50 μm, and the ratio of the sum of the thicknesses of the upper and lower surface layers to the thickness of the core layer is 2:1.

[0539] Example D6

[0540] (1) Preparation of propylene polymer composition A for preparing layer a

[0541] The operation is the same as step (1) in Example D3.

[0542] (2) Preparation of propylene polymer composition B for preparing layer b

[0543] The procedure is the same as step (2) of Example D3, except that the mass fraction of component x, Wx, is 50 parts by weight, and the mass fraction of component y, Wy, is 30 parts by weight. Component y is a polyolefin elastomer (ethylene-1-octene copolymer, octene structural unit content of 36% by weight), brand name 8411, purchased from Dow Chemical Company. This polyolefin elastomer is tested at 230°C and a shear rate of 160 s. -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 1.80, and the elastomer is at 230℃ and a shear rate of 640s. -1 The shear viscosity was 148 Pa·s. The mass fraction of component z, Wz, was 20 parts by weight. Finally, granules of the propylene polymer composition B were obtained, and their melt mass flow rate (MFR) was measured. B = 9.0g / 10min.

[0544] (3) Preparation of composite films:

[0545] The operation is the same as step (3) of Example D3. The film thickness is 50 μm, wherein the ratio of the thickness of the upper surface layer to the thickness of the core layer is 1:4.

[0546] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average dimension of the horizontal axis of the rubber phase was 25 nm, and the average aspect ratio was 19.7.

[0547] Example D7

[0548] (1) Preparation of propylene polymer composition A for preparing layer a

[0549] The operation is the same as step (1) in Example D1.

[0550] (2) Preparation of propylene polymer composition B for preparing layer b

[0551] The operation is the same as step (2) of Example D1, except that the mass fraction of component x, Wx, is 50 parts by weight, the mass fraction of component y, Wy, is 20 parts by weight, and the mass fraction of component z, Wz, is 30 parts by weight. Other operations are the same as in step (1), and finally, granules of the propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 3.7g / 10min.

[0552] (3) Preparation of composite films:

[0553] The operation is the same as step (3) of Example D1. The film thickness is 50 μm, wherein the thickness ratio of layer b to layer a is 1:3.

[0554] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the horizontal axis of the rubber phase was 67 nm, and the average aspect ratio was 17.5.

[0555] Example D8

[0556] The composite film was prepared according to the method of Example D1, except that in the preparation of propylene polymer composition A, the mass fraction Wa of component a was 50 parts by weight, and the mass fraction Wb of component b was 50 parts by weight. Finally, granules of propylene polymer composition A were obtained, and their melt flow rate (MFR) was measured. A = 3.6g / 10min.

[0557] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average dimension of the rubber phases along the horizontal axis was 190 nm, and the average aspect ratio was 5.1.

[0558] Example D9

[0559] The composite film was prepared according to the method of Example D1, except that in the preparation of the propylene polymer composition B, the mass fraction of component x (Wx) was 40 parts by weight, the mass fraction of component y (Wy) was 30 parts by weight, and the mass fraction of component z (Wz) was 30 parts by weight. Particles of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 4.4g / 10min.

[0560] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the horizontal axis of the rubber phase was 145 nm, and the average aspect ratio was 7.8.

[0561] Example D10

[0562] The composite film was prepared according to the method of Example D1, except that in the preparation of the propylene polymer composition B, the mass fraction of component x (Wx) was 50 parts by weight, the mass fraction of component y (Wy) was 40 parts by weight, and the mass fraction of component z (Wz) was 10 parts by weight. Granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 5.1g / 10min.

[0563] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average dimension of the rubber phases along the horizontal axis was 85 nm, and the average aspect ratio was 18.3.

[0564] Example D11

[0565] Propylene polymer composition A was prepared according to the method of Example D3, and propylene polymer composition B was prepared according to the method of Example D2, such that (ηA) 160 -ηB 160 ) and (ηA 640 -ηB 640 All values ​​are less than 0. The composite film was prepared according to the method in Example D3.

[0566] Comparative Example D1

[0567] The composite film was prepared according to the method of Example D1, except that the polyolefin elastomer b was replaced with a polyolefin elastomer of grade DF740 (purchased from Mitsui Chemicals Co., Ltd., which is effective at 230°C and a shear rate of 160 s). -1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 1.63, and the elastomer is at 230℃ and a shear rate of 640s. -1 The shear viscosity is 554 Pa·s. The melt mass flow rate (MFR) of propylene polymer composition A is... A = 2.6 g / 10 min. Film thickness is 50 μm.

[0568] Comparative Example D2

[0569] The composite film was prepared according to the method in Example D2, except that the polyolefin elastomer y was replaced with a polyolefin elastomer of grade DF740 (purchased from Mitsui Chemicals Co., Ltd., which is effective at 230°C and a shear rate of 160 s).-1 and 640s -1 The ratio of shear viscosity η 160 / η 640 The value is 1.63, and the elastomer is at 230℃ and a shear rate of 640s. -1 The shear viscosity was 554 Pa·s. Granules of propylene polymer composition B were obtained, and their melt mass flow rate (MFR) was measured. B = 4.2 g / 10 min. Film thickness is 50 μm.

[0570] Comparative Example D3

[0571] The composite film was prepared according to the method of Example D1, except that the propylene polymer composition B contained only component x.

[0572] Comparative Example D4

[0573] The composite film was prepared according to the method of Example D1, except that the propylene polymer composition B contained only component x and component y, wherein the mass part Wx of component x was 85 parts by weight and the mass part Wy of component y was 15 parts by weight.

[0574] Example D12

[0575] The composite film was prepared according to the method of Example D2, except that the propylene polymer composition B contained only component x and component z, wherein the mass fraction Wx of component x was 70 parts by weight and the mass fraction Wz of component z was 30 parts by weight.

[0576] Comparative Example D5

[0577] The composite film was prepared according to the method of Example D2. The difference is that the propylene polymer composition A contains only component a.

[0578] Table 5

[0579]

[0580] Table 6

[0581]

[0582]

[0583] The results in Tables 5 and 6 show that the composite film according to the present invention exhibits both good impact resistance and optical properties. Compared with composite films not based on the present invention, the composite film of the present invention has better overall performance, especially when using a polyolefin elastomer with a specific shear viscosity, resulting in stable film surface and significantly improved uniformity of film thickness and impact resistance during extrusion casting.

[0584] Example E1

[0585] (1) Preparation of propylene polymer composition A for preparing layer a:

[0586] Component a is a propylene impact copolymer of grade J410F (purchased from Hyosung, South Korea), with an average rubber phase particle size of 600 nm, a maximum rubber phase particle size of 800 nm, an ethylene unit content of 5.3 wt%, and an ethylene-propylene copolymer content of 7.2 wt%. In its room-temperature xylene-soluble fraction, the ethylene unit content is 26.0 wt%. The ethylene unit group [EEE] content is 6.9 wt%. The melt flow rate is 4.6 g / 10 min. Figure 6a The image shows an SEM photograph of the cross-section of the propylene impact copolymer sample. Component b is homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical Co., Ltd., with a melt flow rate of 3.0 g / 10 min and a molecular weight distribution Mw / Mn of 4.6). Component c is polyolefin elastomer of grade DF840 (purchased from Mitsui Chemicals, an ethylene-1-butene copolymer). The components prepared above were weighed and mixed according to the specified proportions, wherein the mass fraction Wa of component a was 65 parts by weight, the mass fraction Wb of component b was 30 parts by weight, and the mass fraction Wc of component c was 5 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, and based on a total mass of 100 parts by weight for components a, b, and c, the amount of lubricant added is 0.1 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of propylene polymer composition A are obtained. The melt mass flow rate (MFR) is measured. A = 4.1g / 10min.

[0587] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0588] Component x is a random copolymer of propylene, grade F500EPS (purchased from Shanghai Petrochemical, an ethylene-propylene-butene terpolymer with a melt flow rate of 5.3 g / 10 min); component y is a polyolefin elastomer, grade DF840 (purchased from Mitsui Chemicals, an ethylene-1-butene copolymer). The components prepared above were weighed and mixed according to the specified proportions, with component x having a mass fraction (Wx) of 90 parts by weight and component y having a mass fraction (Wy) of 10 parts by weight. Other operations were performed as in step (1), finally yielding granules of the propylene polymer composition B. The melt flow rate (MFR) was measured. B = 5.6g / 10min.

[0589] (3) Preparation of composite films:

[0590] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the upper and lower surface extruders of the multilayer extrusion casting machine. An inorganic anti-sticking agent (silica, as above) is added to both the upper and lower surface extruders, with a weight ratio of anti-sticking agent to propylene polymer composition granules of 0.2:100. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film consisting of upper and lower surface layers (layer b) and a core layer (layer a). The film thickness is 50 μm, and the sum of the thicknesses of the upper and lower surface layers is 1:1 with the thickness of the core layer.

[0591] An atomic force microscope image of the cross-section of the composite film is shown below. Figure 7 As shown, the black portion represents the rubber phase, which is dispersed, strip-shaped, and arranged parallel to each other. The average dimension of the rubber phase along its horizontal axis is 53 nm, and the average aspect ratio is 5.2.

[0592] Example E2

[0593] (1) Preparation of propylene polymer composition A for preparing layer a:

[0594] Component a is a propylene impact copolymer of grade F200R (purchased from Shanghai Petrochemical, with an ethylene unit content of 9.1 wt% and an ethylene-propylene copolymer content of 12.2 wt%. The average particle size of the rubber phase is 800 nm, the maximum particle size is 1 μm, and the ethylene unit content in its room temperature xylene-soluble fraction is 38.1 wt%. The ethylene unit group [EEE] content is 13.6 wt%. The melt flow rate is 2.1 g / 10 min); component b is a homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical, with a melt flow rate of 3.1 g / 10 min and a molecular weight distribution Mw / Mn of 4.7); component c is a polyolefin elastomer of grade 8200 (purchased from Dow Chemical, ethylene-1-octene copolymer). The components obtained above were weighed and mixed according to the specified proportions, where component a (Wa) had 75 parts by weight, component b (Wb) had 10 parts by weight, and component c (Wc) had 15 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, with 0.1 parts by weight based on the total mass of components a, b, and c being 100 parts by weight) was added. The mixture was then added to a high-speed mixer and mixed thoroughly. The mixed material was then fed into the feeder of a twin-screw extruder manufactured by W&P. The material entered the twin screws through the feeder. During processing, the screw temperature was maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, propylene polymer composition A granules were obtained. The melt mass flow rate (MFR) was measured. A =3.3g / 10min).

[0595] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0596] Component x is a propylene random copolymer of grade F5006 (purchased from Yanshan Petrochemical, ethylene-propylene-butene terpolymer, melt flow rate of 5.2 g / 10 min); component y is a polyolefin elastomer of grade 8200 (purchased from Dow Chemical, ethylene-1-octene copolymer). The components prepared above were weighed and mixed according to the specified proportions, wherein the mass fraction Wx of component x was 75 parts by weight and the mass fraction Wy of component y was 25 parts by weight. Other operations were performed as in step (1), finally yielding granules of the propylene polymer composition B. The melt flow rate (MFR) was measured. B = 4.2g / 10min.

[0597] (3) Preparation of composite films:

[0598] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the top surface extruder of the same machine. An inorganic anti-sticking agent (silica, as above) is added to the top surface extruder, and the weight ratio of the anti-sticking agent to the propylene polymer composition granules is 0.2:100. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film consisting of an upper surface layer (layer b) and a core layer (layer a). The film thickness is 50 μm, and the thickness ratio of layer b to layer a is 1:2.

[0599] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 62 nm, and the average aspect ratio was 11.2.

[0600] Example E3

[0601] Component a is a propylene impact copolymer of grade PPB-M02D (average rubber phase particle size 1.4 μm, maximum rubber phase particle size 1.9 μm, purchased from Maoming Petrochemical, ethylene content 8 wt%, ethylene-propylene copolymer content 10 wt%, ethylene unit content in room temperature xylene solubles 36.3 wt%, ethylene unit group [EEE] content 18.5 wt%, melt flow rate 1.5 g / 10 min); component b is a propylene-ethylene binary random copolymer polypropylene of grade F800EDF (purchased from Shanghai Petrochemical, melt flow rate 7.8 g / 10 min); component c is a polyolefin elastomer of grade VM3980 (purchased from Exxon, propylene-ethylene copolymer). The components obtained above were weighed and mixed according to the specified proportions, where component a (Wa) had a mass fraction of 55 parts by weight, component b (Wb) had a mass fraction of 25 parts by weight, and component c (Wc) had a mass fraction of 20 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, with a molecular weight of 10,000, and based on a total mass fraction of 100 parts by weight for components a, b, and c, the amount of lubricant added was 0.1 parts by weight). The mixture was then added to a high-speed mixer and mixed thoroughly. The mixed material was then fed into the feeder of a twin-screw extruder manufactured by W&P. The material entered the twin screws through the feeder. During processing, the screw temperature was maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of the propylene polymer composition A were obtained. The melt mass flow rate (MFR) was measured. A = 6.4g / 10min.

[0602] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0603] Component x is a random copolymer of propylene with grade F800EDF (purchased from Shanghai Petrochemical, a propylene-ethylene binary copolymer with a melt flow rate of 7.8 g / 10 min); component y is a polyolefin elastomer with grade VM3980 (purchased from ExxonMobil, a propylene-ethylene copolymer). The components prepared above were weighed and mixed according to the specified proportions, wherein the mass fraction Wx of component x was 80 parts by weight and the mass fraction Wy of component y was 20 parts by weight. Other operations were performed as in step (1), finally yielding granules of the propylene polymer composition B. The melt flow rate (MFR) was measured. B = 8.3g / 10min.

[0604] (3) Preparation of composite films:

[0605] The procedure is the same as step (3) in Example E1. Finally, a film with a thickness of 50 μm is obtained, wherein the sum of the thicknesses of the upper and lower surface layers is 1:4 to the thickness of the core layer.

[0606] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the horizontal axis of the rubber phase was 143 nm, and the average aspect ratio was 8.7.

[0607] Example E4

[0608] (1) Preparation of propylene polymer composition A for preparing layer a:

[0609] The procedure is the same as step (1) in Example E2, except that the mass fraction Wa of component a is 80 parts by weight, the mass fraction Wb of component b is 18 parts by weight, and the mass fraction Wc of component c is 2 parts by weight. Component c is a polyolefin elastomer of grade 8411 (purchased from Dow Chemical Company, an ethylene-1-octene copolymer). Granules of the propylene polymer composition A were obtained, and their melt flow rate (MFR) was measured. A = 3.1g / 10min.

[0610] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0611] The operation is the same as step (2) of Example E2, except that the mass fraction of component x, Wx, is 92 parts by weight, and the mass fraction of component y, Wy, is 8 parts by weight. Other operations are the same as in step (1), and finally, granules of the propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 7.5g / 10min.

[0612] (3) Preparation of composite films:

[0613] The procedure is the same as step (3) in Example E2. The film thickness is 50 μm, wherein the thickness ratio of layer b to layer a is 1:6.

[0614] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average dimension of the rubber phases was 77 nm and the average aspect ratio was 5.6.

[0615] Example E5

[0616] (1) Preparation of propylene polymer composition A for preparing layer a:

[0617] The procedure is the same as step (1) of Example E1, except that the mass fraction Wa of component a is 90 parts by weight, the mass fraction Wb of component b is 5 parts by weight, and the mass fraction Wc of component c is 5 parts by weight. Pellets of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 5.1g / 10min.

[0618] (2) Preparation of propylene polymer composition B:

[0619] The procedure is the same as step (2) of Example E2, except that the mass fraction of component x, Wx, is 80 parts by weight, and the mass fraction of component y, Wy, is 20 parts by weight. Finally, granules of the propylene polymer composition B are obtained, and their melt flow rate (MFR) is measured. B = 3.5g / 10min.

[0620] (3) Preparation of composite films:

[0621] The operation is the same as step (3) of Example E1. The film thickness is 50 μm, wherein the sum of the thicknesses of the upper and lower surface layers is 2:1 to the thickness of the core layer.

[0622] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped and parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 25 nm, and the average aspect ratio was 14.6.

[0623] Example E6

[0624] (1) Preparation of propylene polymer composition A for preparing layer a:

[0625] The procedure is the same as step (1) of Example E3, except that the mass fraction Wa of component a is 50 parts by weight, the mass fraction Wb of component b is 40 parts by weight, and the mass fraction Wc of component c is 10 parts by weight. Granules of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A= 2.3g / 10min.

[0626] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0627] The procedure is the same as step (2) of Example E3, except that the mass fraction of component x, Wx, is 60 parts by weight, and the mass fraction of component y, Wy, is 40 parts by weight. Finally, granules of the propylene polymer composition B are obtained, and their melt flow rate (MFR) is measured. B = 9.6g / 10min.

[0628] (3) Preparation of composite film: The operation is the same as step (3) of Example E3.

[0629] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 138 nm, and the average aspect ratio was 6.3.

[0630] Example E7

[0631] (1) Preparation of propylene polymer composition A for preparing layer a:

[0632] The procedure is the same as step (1) of Example E2, except that the mass fraction Wa of component a is 50 parts by weight, the mass fraction Wb of component b is 20 parts by weight, and the mass fraction Wc of component c is 30 parts by weight. Granules of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 3.6g / 10min.

[0633] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0634] The procedure is the same as step (2) of Example E2, except that the mass fraction of component x, Wx, is 85 parts by weight, and the mass fraction of component y, Wy, is 15 parts by weight. Other procedures are the same as in step (1), and finally, granules of the propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 4.3g / 10min.

[0635] (3) Preparation of composite films:

[0636] The procedure is the same as step (3) in Example E2. The film thickness is 50 μm, wherein the thickness ratio of layer b to layer a is 1:3.

[0637] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped and parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 106 nm, and the average aspect ratio was 8.6.

[0638] Example E8

[0639] The composite film was prepared according to the method of Example E2, except that in the preparation of propylene polymer composition A, the mass fraction Wa of component a was 40 parts by weight, the mass fraction Wb of component b was 40 parts by weight, and the mass fraction Wc of component c was 20 parts by weight. Granules of propylene polymer composition A were obtained, and their melt flow rate (MFR) was measured. A = 3.3g / 10min.

[0640] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped and parallel rubber phases were visible. The average dimension of the rubber phases was 94 nm and the average aspect ratio was 9.3.

[0641] Example E9

[0642] The composite film was prepared according to the method of Example E2, except that in the preparation of propylene polymer composition B, the mass fraction of component x, Wx, was 95 parts by weight, and the mass fraction of component y, Wy, was 5 parts by weight. Finally, granules of propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 5.5g / 10min.

[0643] Example E10

[0644] The composite film was prepared according to the method of Example E2, except that in the preparation of propylene polymer composition B, the mass fraction of component x, Wx, was 70 parts by weight, and the mass fraction of component y, Wy, was 30 parts by weight. Finally, granules of propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 4.7g / 10min.

[0645] Example E11

[0646] The composite film was prepared according to the method of Example E2, except that in the preparation of propylene polymer composition B, the mass fraction of component x, Wx, was 40 parts by weight, and the mass fraction of component y, Wy, was 60 parts by weight. Finally, granules of propylene polymer composition B were obtained, and their melt mass flow rate (MFR) was measured. B = 3.2g / 10min.

[0647] Comparative Example E1

[0648] The composite film was prepared according to the method of Example E2, except that in the preparation of the propylene polymer composition A, the propylene impact copolymer was replaced with propylene impact copolymer of grade F780R (purchased from Shanghai Petrochemical, with an average rubber phase particle size of 2.0 μm, a maximum rubber phase particle size of 3.0 μm, an ethylene unit content of 9.0 wt%, and an ethylene-propylene copolymer content of 17.1 wt%. The melt mass flow rate was 7.3 g / 10 min. Figure 6b (This is an SEM image of the cross-section of the propylene impact copolymer sample). Finally, granules of propylene polymer composition A were obtained, and their melt mass flow rate (MFR) was measured. A = 7.7g / 10min.

[0649] Example E12

[0650] The composite film was prepared according to the method of Example E2, except that the propylene polymer composition A contained only component a and component b, wherein the mass part Wa of component a was 75 parts by weight and the mass part Wb of component b was 25 parts by weight.

[0651] Comparative Example E2

[0652] The composite film was prepared according to the method of Example E2, except that the propylene polymer composition A contained only component a and component c, wherein the mass part Wa of component a was 75 parts by weight and the mass part Wc of component c was 25 parts by weight.

[0653] Table 7

[0654]

[0655] The results in Table 7 show that the composite film with the microstructure according to the present invention exhibits both good impact resistance and optical properties, and even good heat-sealing strength. In contrast, composite films prepared using propylene impact copolymers not according to the present invention, which do not possess the microstructure according to the present invention, have poor optical or impact resistance, and the film surface is unstable during extrusion casting, making it difficult to obtain films with uniform thickness.

[0656] Example F1

[0657] (1) Preparation of propylene polymer composition A for preparing layer a

[0658] Component a is a homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical Co., Ltd., with a melt flow rate of 3.1 g / 10 min, isotacticity of 98%, and molecular weight distribution Mw / Mn of 4.7); component b is a polyolefin elastomer of grade 8411 (purchased from Dow Chemical Co., Ltd., which is an ethylene-1-octene copolymer). The components obtained above were weighed and mixed according to the specified proportions, wherein the mass fraction Wa of component a was 80 parts by weight and the mass fraction Wb of component b was 20 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, and based on a total mass of 100 parts by weight for components a and b, the amount of lubricant added is 0.1 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of propylene polymer composition A are obtained. The melt flow rate (MFR) is then measured. A = 3.4g / 10min.

[0659] (2) Preparation of propylene polymer composition B for preparing layer b

[0660] Component x is a propylene random copolymer of grade F5006 (purchased from Yanshan Petrochemical, an ethylene-propylene-butene terpolymer with a melt flow rate of 5.2 g / 10 min); component y is a polyolefin elastomer of grade 8200 (purchased from Dow Chemical, an ethylene-1-octene copolymer); component z is a polypropylene impact copolymer of grade PPB-MO2D, with an average rubber phase particle size of 1.4 μm and a maximum rubber phase particle size of 1.9 μm, purchased from Maoming Petrochemical, with an ethylene content of 8% by weight and a melt flow rate of 1.5 g / 10 min). The components prepared above were weighed and mixed according to the specified proportions, wherein the mass fraction of component x (Wx) was 85 parts by weight, the mass fraction of component y (Wy) was 5 parts by weight, and the mass fraction of component z (Wz) was 10 parts by weight. The other steps are the same as in step (1), and finally the granules of propylene polymer composition B are obtained. The melt mass flow rate MFRB is tested to be 4.8 g / 10 min.

[0661] (3) Preparation of composite films:

[0662] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the top surface extruder of the same machine. An inorganic anti-sticking agent (silica, as above) is added to the top surface extruder, with a weight ratio of anti-sticking agent to propylene polymer composition granules of 0.2:100. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film consisting of an upper surface layer (layer b) and a core layer (layer a). The film thickness is 50 μm, and the thickness ratio of layer b to layer a is 1:2.

[0663] Atomic force microscopy images of the cross-section of the composite film show the presence of a rubber phase in the film. The rubber phase is uniformly dispersed, strip-shaped, and arranged parallel to each other. The average dimension of the rubber phase along its horizontal axis is 128 nm, and the average aspect ratio is 5.2.

[0664] Example F2

[0665] (1) Preparation of propylene polymer composition A for preparing layer a:

[0666] Component a is a propylene impact copolymer of brand name F200R (purchased from Shanghai Petrochemical, with an average rubber phase particle size of 800 nm, a maximum rubber phase particle size of 1 μm, an ethylene content of 9.1 wt%, an ethylene-propylene copolymer content of 12.2 wt%, and in its room temperature xylene-soluble fraction, an ethylene unit content of 38.1 wt%, an ethylene unit group [EEE] content of 13.6 wt%, and a melt flow rate of 2.1 g / 10 min); component b is a polyolefin elastomer of brand name DF840 (purchased from Mitsui Chemicals, an ethylene-1-butene copolymer). The components obtained above were weighed and mixed according to the specified proportions, wherein the mass fraction Wa of component a was 95 parts by weight, and the mass fraction Wb of component b was 5 parts by weight. Then, a lubricant (a PEG lubricant manufactured by Clariant AG, Switzerland, with a molecular weight of 10,000, and 0.1 parts by weight based on a total mass of 100 parts by weight of components a and b) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, propylene polymer composition A granules are obtained. The melt flow rate (MFR) is then measured. A = 3.6g / 10min.

[0667] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0668] Component x is a random copolymer of propylene (F500EPS, purchased from Shanghai Petrochemical, an ethylene-propylene-butene terpolymer with a melt flow rate of 5.3 g / 10 min); component y is a polyolefin elastomer (DF840, purchased from Mitsui); and component z is a polypropylene impact copolymer (F200R). The components prepared above were weighed and mixed according to the specified proportions, wherein component x (Wx) had a mass fraction of 60 parts by weight, component y (Wy) had a mass fraction of 20 parts by weight, and component z (Wz) had a mass fraction of 20 parts by weight. Other steps were the same as in step (1), ultimately yielding granules of the propylene polymer composition B. The melt flow rate (MFR) of the granules was then measured. B = 4.3g / 10min.

[0669] (3) Preparation of composite films:

[0670] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the upper and lower surface extruders of the multilayer extrusion casting machine. An inorganic anti-sticking agent (silica, as above) is added to both the upper and lower surface extruders, with a weight ratio of anti-sticking agent to propylene polymer composition granules of 0.2:100. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film consisting of upper and lower surface layers (layer b) and a core layer (layer a). The film thickness is 50 μm, and the sum of the thicknesses of the upper and lower surface layers is 1:1 to the thickness of the core layer.

[0671] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 88 nm, and the average aspect ratio was 7.5.

[0672] Example F3

[0673] (1) Preparation of propylene polymer composition A for preparing layer a:

[0674] Component a is homopolymer polypropylene of grade FC801 (purchased from Shanghai Petrochemical, melt flow rate 7.8 g / 10 min, isotacticity 98%, molecular weight distribution Mw / Mn 4.8); component b is polyolefin elastomer of grade VM3980 (purchased from ExxonMobil, propylene-ethylene copolymer, ethylene structural unit content 9% by weight). The components obtained above were weighed and mixed according to the specified proportions, wherein component a (W) had a mass fraction Wa of 85 parts by weight and component b (Wb) had a mass fraction Wb of 15 parts by weight. Then, a lubricant (a PEG lubricant manufactured by Clariant AG, Switzerland, with a molecular weight of 10,000, and 0.1 parts by weight based on a total mass of 100 parts by weight of components a and b) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, propylene polymer composition A granules are obtained. The melt flow rate (MFR) is then measured. A = 7.4g / 10min.

[0675] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0676] Component x is a propylene random copolymer of grade F800EPS (purchased from Shanghai Petrochemical, an ethylene-propylene-butene terpolymer with a melt flow rate of 8.2 g / 10 min); component y is a polyolefin elastomer of grade VM3980 (purchased from ExxonMobil, a propylene-ethylene copolymer with an ethylene structural unit content of 9 wt%); component z is a polypropylene impact copolymer of grade J410F (purchased from Hyosung, South Korea, with an average rubber phase particle size of 600 nm, a maximum rubber phase particle size of 800 nm, an ethylene content of 5.3 wt%), and an ethylene-propylene copolymer content of 9 wt%. The polymer content is 7.2% by weight, and the ethylene unit content in its room temperature xylene-soluble fraction is 26.0% by weight, the ethylene unit group [EEE] content is 6.9% by weight, and the melt mass flow rate is 4.6 g / 10 min. The components prepared above are weighed and mixed according to the proportions, wherein the mass part of component x (Wx) is 85 parts by weight, the mass part of component y (Wy) is 10 parts by weight, and the mass part of component z (Wz) is 5 parts by weight. Other steps are the same as in step (1), and finally, granules of propylene polymer composition B are obtained. The melt mass flow rate (MFR) of the granules is tested. B = 8.4g / 10min.

[0677] (3) Preparation of composite films:

[0678] The preparation process is the same as step (3) of Example F1.

[0679] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 54 nm, and the average aspect ratio was 9.8.

[0680] Example F4

[0681] (1) Preparation of propylene polymer composition A for preparing layer a:

[0682] The procedure is the same as step (1) of Example F1, except that the mass fraction Wa of component a is 70 parts by weight and the mass fraction Wb of component b is 30 parts by weight. Pellets of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 3.5g / 10min.

[0683] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0684] The steps are the same as step (2) in Example F1, except that the mass fraction of component x, Wx, is 90 parts by weight, the mass fraction of component y, Wy, is 5 parts by weight, and the mass fraction of component z, Wz, is 5 parts by weight. Other operations are the same as in step (1), and finally, granules of the propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 5.5g / 10min.

[0685] (3) Preparation of composite films:

[0686] The steps are the same as in Example F1. The film thickness is 50 μm, wherein the thickness ratio of layer B to layer A is 1:3.

[0687] Example F5

[0688] (1) Preparation of propylene polymer composition A for preparing layer a:

[0689] The procedure is the same as step (1) of Example F2, except that the mass fraction Wa of component a is 75 parts by weight and the mass fraction Wb of component b is 25 parts by weight. Pellets of propylene polymer composition A are obtained, and their melt flow rate (MFR) is measured. A = 4.0g / 10min.

[0690] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0691] The procedure was the same as in Example F3, except that the mass fraction of component x, Wx, was 85 parts by weight, the mass fraction of component y, Wy, was 13 parts by weight, and the mass fraction of component z, Wz, was 2 parts by weight. Finally, granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 8.2g / 10min.

[0692] (3) Preparation of composite films:

[0693] The operation is the same as in Example F2. The film thickness is 50 μm, and the ratio of the sum of the thicknesses of the upper and lower surface layers to the thickness of the core layer is 2:1.

[0694] Example F6

[0695] (1) Preparation of propylene polymer composition A for preparing layer a:

[0696] The operation is the same as step (1) in embodiment F3.

[0697] (2) Preparation of propylene polymer composition B used to prepare layer a:

[0698] The procedure is the same as step (2) of Example F3, except that the mass fraction of component x, Wx, is 50 parts by weight, the mass fraction of component y, Wy, is 30 parts by weight, and component y is a polyolefin elastomer (ethylene-1-octene copolymer, purchased from Dow Chemical Company) with brand name 8411. The mass fraction of component z, Wz, is 20 parts by weight. Finally, granules of propylene polymer composition B are obtained, and their melt flow rate (MFR) is measured. B = 8.6g / 10min.

[0699] (3) Preparation of composite films:

[0700] The procedure is the same as step (3) of Example F3. The film thickness is 50 μm, wherein the ratio of the thickness of the upper surface layer to the thickness of the core layer is 1:4.

[0701] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average dimension of the rubber phases along the horizontal axis was 28 nm, and the average aspect ratio was 14.5.

[0702] Example F7

[0703] (1) Preparation of propylene polymer composition A for preparing layer a:

[0704] The operation is the same as step (1) of embodiment F1.

[0705] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0706] The operation is the same as step (2) of Example F1, except that the mass fraction of component x, Wx, is 50 parts by weight, the mass fraction of component y, Wy, is 20 parts by weight, and the mass fraction of component z, Wz, is 30 parts by weight. Other operations are the same as in step (1), and finally, granules of the propylene polymer composition B are obtained. The melt flow rate (MFR) is measured. B = 4.3g / 10min.

[0707] (3) Preparation of composite films:

[0708] The procedure is the same as step (3) of Example F1. The film thickness is 50 μm, wherein the thickness ratio of layer B to layer A is 1:3.

[0709] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 147 nm, and the average aspect ratio was 6.3.

[0710] Example F8

[0711] The composite film was prepared according to the method of Example F1, except that in the preparation of propylene polymer composition A, the mass fraction Wa of component a was 50 parts by weight, and the mass fraction Wb of component b was 50 parts by weight. Finally, granules of propylene polymer composition A were obtained, and their melt mass flow rate (MFR) was measured. A = 3.6g / 10min.

[0712] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 120 nm, and the average aspect ratio was 5.5.

[0713] Example F9

[0714] The composite film was prepared according to the method of Example F1, except that in the preparation of the propylene polymer composition B, the mass fraction of component x (Wx) was 40 parts by weight, the mass fraction of component y (Wy) was 30 parts by weight, and the mass fraction of component z (Wz) was 30 parts by weight. Granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 4.2g / 10min.

[0715] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 145 nm, and the average aspect ratio was 7.4.

[0716] Example F10

[0717] The composite film was prepared according to the method of Example F1, except that in the preparation of the propylene polymer composition B, the mass fraction of component x (Wx) was 50 parts by weight, the mass fraction of component y (Wy) was 40 parts by weight, and the mass fraction of component z (Wz) was 10 parts by weight. Granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 5.3g / 10min.

[0718] When the composite film was observed under an atomic force microscope, dispersed, strip-shaped, parallel rubber phases were visible. The average size of the rubber phases along the horizontal axis was 102 nm, and the average aspect ratio was 9.3.

[0719] Comparative Example F1

[0720] The composite film was prepared according to the method in Example F1, except that in the preparation of the propylene polymer composition B, the polypropylene impact copolymer z was replaced with a polypropylene impact copolymer of grade F780R (purchased from Shanghai Petrochemical, with an average particle size of 2.0 μm and a maximum particle size of 3.0 μm in the rubber phase, an ethylene unit content of 9.0 wt%, an ethylene-propylene copolymer content of 17.1 wt%, and a melt flow rate of 7.3 g / 10 min). Finally, granules of the propylene polymer composition B were obtained, and their melt flow rate (MFR) was measured. B = 7.9 g / 10 min. Film thickness is 50 μm.

[0721] Comparative Example F2

[0722] The composite film was prepared according to the method of Example F2, except that component a in composition A and component z in composition B were replaced with a propylene impact copolymer of grade F780R, resulting in granules of propylene polymer composition A (melt mass flow rate MFR). A =7.3 g / 10 min) and granules of propylene polymer composition B (melt mass flow rate MFR) B =6.5g / 10min). The film thickness is 50μm.

[0723] Comparative Example F3

[0724] The composite film was prepared according to the method of Example F1, except that the propylene polymer composition B contained only component x.

[0725] Comparative Example F4

[0726] The composite film was prepared according to the method of Example F1, except that the propylene polymer composition B contained only component x and component y, wherein the mass fraction Wx of component x was 85 parts by weight and the mass fraction Wy of component y was 15 parts by weight.

[0727] Comparative Example F5

[0728] The composite film was prepared according to the method of Example F2, except that the propylene polymer composition B contained only component x and component z, wherein the mass fraction Wx of component x was 70 parts by weight and the mass fraction Wz of component z was 30 parts by weight.

[0729] Table 8

[0730]

[0731] The results in Table 8 show that the composite film prepared using the propylene impact copolymer according to the present invention, which has the microstructure according to the present invention, exhibits excellent impact resistance and optical properties, as well as good tensile properties and good heat-sealing strength. In contrast, the composite film prepared using the propylene impact copolymer not according to the present invention, which does not have the microstructure according to the present invention, has poor optical properties or impact resistance, as well as poor tensile properties or heat-sealing strength; moreover, during extrusion casting, the film surface is unstable, making it difficult to obtain a film with uniform thickness.

[0732] Example G1 (using maleic anhydride-modified polypropylene)

[0733] (1) Preparation of propylene polymer composition A for preparing layer a:

[0734] Component a is a homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical Co., Ltd., with a melt flow rate of 3.1 g / 10 min, isotacticity of 98%, and molecular weight distribution Mw / Mn of 4.7); component b is a propylene impact copolymer of grade EP200K (purchased from Zhongsha Petrochemical Co., Ltd., with an ethylene content of 8% by weight and a melt flow rate of 3.2 g / 10 min); and component c is a polyolefin elastomer of grade 6102 (purchased from ExxonMobil, an ethylene-propylene copolymer). The components obtained above were weighed and mixed according to the specified proportions, wherein component a (W) had a mass fraction Wa of 75 parts by weight, component b (Wb) had a mass fraction Wb of 10 parts by weight, and component c (Wc) had a mass fraction Wc of 15 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant FL7540L, with a molecular weight of 10,000, and based on a total mass of 100 parts by weight for components a, b, and c, the amount of lubricant added is 0.1 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of propylene polymer composition A are obtained. The melt flow rate (MFR) is then measured. A= 3.6g / 10min.

[0735] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0736] Component x is a random copolymer of propylene, grade F5006 (purchased from Yanshan Petrochemical, an ethylene-propylene-butene terpolymer with a melt flow rate of 5.2 g / 10 min); component y is a polyolefin elastomer, grade 6102 (purchased from ExxonMobil, an ethylene-propylene copolymer); and component z is maleic anhydride modified polypropylene, grade QF551A (purchased from Mitsui Chemicals). The components prepared above were weighed and mixed according to the specified ratio, where component x (Wx) had a mass fraction of 70 parts by weight, component y (Wy) had a mass fraction of 15 parts by weight, and component z (Wz) had a mass fraction of 15 parts by weight. The ratio of Wc to Wy was 1:1. Other steps were the same as in step (1), and finally, granules of the propylene polymer composition B were obtained. The melt flow rate (MFR) of the granules was then tested. B = 3.5g / 10min.

[0737] (3) Preparation of composite films:

[0738] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the top surface extruder of the same machine. An inorganic anti-sticking agent (silica, as above) is added to the top surface extruder, with a weight ratio of anti-sticking agent to propylene polymer composition granules of 0.2:100. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film consisting of an upper surface layer (layer b) and a core layer (layer a). The composite film thickness is 50 μm, with a thickness ratio of layer b to layer a of 1:2.

[0739] The composite film was observed under an atomic force microscope, revealing a rubber phase with an average horizontal dimension of 65 nm and an average aspect ratio of 10.9.

[0740] Example G2 (using polypropylene-glycidyl methacrylate)

[0741] I. Preparation of polypropylene-glycidyl methacrylate

[0742] The basic copolymer polypropylene powder with the following characteristics was selected: ethylene content of comonomer 18.1 wt%, xylene-soluble content 48.7 wt%, comonomer content in soluble matter 31.9 wt%, soluble matter / copolymer polypropylene intrinsic viscosity ratio 0.89, and weight-average molecular weight 34.3 × 10⁻⁶. 4The MFR (Mean Flow Rate) at 230℃ and 2.16kg load was 1.21g / 10min, Tm = 143.4℃, and fine powder smaller than 40 mesh was removed by sieving. 2.0kg of the above-mentioned basic copolymer polypropylene powder was weighed and added to a 10L reactor equipped with a mechanical stirrer. The reaction system was sealed, and nitrogen was used for purging and deoxygenation. 2.5g of benzoyl peroxide and 80g of glycidyl methacrylate were added, stirred and mixed for 30min, and the temperature was raised to 90℃ for 4 hours. After the reaction, nitrogen was purged and the mixture cooled to obtain polypropylene-glycidyl methacrylate with a melt flow rate of 0.49g / 10min, M1 of 2.96%, and grafting efficiency of 77%.

[0743] II. Preparation of Composite Thin Films

[0744] (1) Preparation of propylene polymer composition A for preparing layer a:

[0745] Component a is homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical Co., Ltd., melt flow rate 3.1 g / 10 min, isotacticity 98%, molecular weight distribution Mw / Mn 4.7); component b is polypropylene-glycidyl methacrylate prepared as above; component c is polyolefin elastomer of grade 6102 (purchased from ExxonMobil, ethylene-propylene copolymer). The components prepared above were weighed and mixed according to the specified proportions, wherein component a (Wa) had a mass fraction of 75 parts by weight, component b (Wb) had a mass fraction of 10 parts by weight, and component c (Wc) had a mass fraction of 15 parts by weight. Then, a lubricant (a PEG lubricant manufactured by Clariant AG, Switzerland, with a molecular weight of 10,000, and 0.1 parts by weight based on a total mass of 100 parts by weight of components a, b, and c) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of the propylene polymer composition A are obtained. The melt flow rate (MFR) is then measured. A = 2.8g / 10min.

[0746] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0747] Component x is a random copolymer of propylene, grade F5006 (purchased from Yanshan Petrochemical, an ethylene-propylene-butene terpolymer with a melt flow rate of 5.2 g / 10 min); component y is a polyolefin elastomer, grade 6102 (purchased from ExxonMobil, an ethylene-propylene copolymer). The components prepared above were weighed and mixed according to the specified ratio, wherein the mass fraction of component x, Wx, was 75 parts by weight, and the mass fraction of component y, Wy, was 25 parts by weight. The ratio of Wc to Wy was 3:5. Other steps were the same as in step (1), finally yielding granules of the propylene polymer composition B. The melt flow rate (MFR) of the granules was then tested. B = 3.2g / 10min.

[0748] (3) Preparation of composite films:

[0749] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the top surface extruder of the same machine. An inorganic anti-sticking agent (silica, as above) is added to the top surface extruder, with a weight ratio of anti-sticking agent to propylene polymer composition granules of 0.2:100. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film consisting of an upper surface layer (layer b) and a core layer (layer a). The film thickness is 50 μm, and the thickness ratio of layer b to layer a is 1:2.

[0750] Example G3 (using polypropylene-g-styrene)

[0751] I. Preparation of polypropylene-g-styrene

[0752] The basic copolymer polypropylene powder with the following characteristics was selected: ethylene content of comonomer 18.1 wt%, xylene-soluble content 48.7 wt%, comonomer content in soluble matter 31.9 wt%, soluble matter / copolymer polypropylene intrinsic viscosity ratio 0.89, and weight-average molecular weight 34.3 × 10⁻⁶. 4 The MFR (Mean Flow Rate) at 230℃ and 2.16kg load was 1.21g / 10min, Tm = 143.4℃, and fine powder smaller than 40 mesh was removed by sieving. 2.0kg of the above-mentioned basic copolymer polypropylene powder was weighed and added to a 10L reactor equipped with a mechanical stirrer. The reaction system was sealed, and nitrogen was used for purging to remove oxygen. 2g of benzoyl peroxide and 100g of styrene were added, and the mixture was stirred and mixed for 60min. The mixture swelled at 40℃ for 4 hours, then the temperature was raised to 95℃ and reacted for 4 hours. After the reaction was completed, nitrogen was used to purge and cool the mixture, yielding polypropylene-g-styrene with a melt flow rate of 0.75g / 10min, M1 of 2.91%, and grafting efficiency of 61%.

[0753] II. Preparation of Composite Thin Films

[0754] (1) Preparation of propylene polymer composition A for preparing layer a:

[0755] Component a is homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical Co., Ltd., melt flow rate 3.1 g / 10 min, isotacticity 98%, molecular weight distribution Mw / Mn 4.7); component b is polypropylene-g-styrene prepared as above; component c is polyolefin elastomer of grade 6102 (purchased from ExxonMobil, ethylene-propylene copolymer). The components prepared above were weighed and mixed according to the specified proportions, wherein component a (Wa) had a mass fraction of 75 parts by weight, component b (Wb) had a mass fraction of 10 parts by weight, and component c (Wc) had a mass fraction of 15 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, and based on a total mass of 100 parts by weight for components a, b, and c, the amount of lubricant added is 0.1 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of propylene polymer composition A are obtained. The melt flow rate (MFR) is then measured. A = 2.9g / 10min.

[0756] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0757] Component x is a random copolymer of propylene, grade F5006 (purchased from Yanshan Petrochemical, an ethylene-propylene-butene terpolymer with a melt flow rate of 5.2 g / 10 min); component y is a polyolefin elastomer, grade 6102 (purchased from ExxonMobil, an ethylene-propylene copolymer). The components prepared above were weighed and mixed according to the specified ratio, wherein the mass fraction of component x, Wx, was 75 parts by weight, and the mass fraction of component y, Wy, was 25 parts by weight. The ratio of Wc to Wy was 3:5. Other steps were the same as in step (1), finally yielding granules of the propylene polymer composition B. The melt flow rate (MFR) of the granules was then tested. B = 3.2g / 10min.

[0758] (3) Preparation of composite films:

[0759] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the top surface extruder of the same machine. An inorganic anti-sticking agent (silica, as above) is added to the top surface extruder, with a weight ratio of anti-sticking agent to propylene polymer composition granules of 0.2:100. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film consisting of an upper surface layer (layer b) and a core layer (layer a). The film thickness is 50 μm, and the thickness ratio of layer b to layer a is 1:2.

[0760] Example G4 (using polypropylene-g-vinyltriethoxysilane)

[0761] I. Preparation of polypropylene-g-vinyltriethoxysilane

[0762] The basic copolymer polypropylene powder with the following characteristics was selected: ethylene content of comonomer 18.1 wt%, xylene-soluble content 48.7 wt%, comonomer content in soluble matter 31.9 wt%, soluble matter / copolymer polypropylene intrinsic viscosity ratio 0.89, and weight-average molecular weight 34.3 × 10⁻⁶. 4 The MFR (Mean Flow Rate) at 230℃ and 2.16kg load was 1.21g / 10min, Tm = 143.4℃, and fine powder smaller than 40 mesh was removed by sieving. 2.0kg of the above-mentioned basic copolymer polypropylene powder was weighed and added to a 10L reactor equipped with a mechanical stirrer. The reaction system was sealed, and nitrogen was used for purging to remove oxygen. 2.5g of lauroyl peroxide and 50g of vinyltriethoxysilane were added, stirred and mixed for 30min, swelled at 40℃ for 1 hour, and then the temperature was raised to 90℃ and reacted for 4 hours. After the reaction was completed, nitrogen was purged, and the mixture was cooled to obtain polypropylene-g-vinyltriethoxysilane with a melt flow rate of 1.15g / 10min, M1 of 1.03%, and grafting efficiency of 42%.

[0763] II. Preparation of Composite Thin Films

[0764] (1) Preparation of propylene polymer composition A for preparing layer a:

[0765] Component a is homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical Co., Ltd., with a melt flow rate of 3.1 g / 10 min, isotacticity of 98%, and molecular weight distribution Mw / Mn of 4.7); component b is polypropylene-g-vinyltriethoxysilane prepared as above; and component c is polyolefin elastomer of grade 6102 (purchased from ExxonMobil, an ethylene-propylene copolymer). The components prepared above were weighed and mixed according to the specified proportions, wherein component a (Wa) had a mass fraction of 75 parts by weight, component b (Wb) had a mass fraction of 10 parts by weight, and component c (Wc) had a mass fraction of 15 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, and based on a total mass of 100 parts by weight for components a, b, and c, the amount of lubricant added is 0.1 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of propylene polymer composition A are obtained. The melt flow rate (MFR) is then measured. A = 3.0g / 10min.

[0766] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0767] Component x is a random copolymer of propylene, grade F5006 (purchased from Yanshan Petrochemical, an ethylene-propylene-butene terpolymer with a melt flow rate of 5.2 g / 10 min); component y is a polyolefin elastomer, grade 6102 (purchased from ExxonMobil, an ethylene-propylene copolymer). The components prepared above were weighed and mixed according to the specified ratio, wherein the mass fraction of component x, Wx, was 75 parts by weight, and the mass fraction of component y, Wy, was 25 parts by weight. The ratio of Wc to Wy was 3:5. Other steps were the same as in step (1), finally yielding granules of the propylene polymer composition B. The melt flow rate (MFR) of the granules was then tested. B = 3.2g / 10min.

[0768] (3) Preparation of composite films:

[0769] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the top surface extruder of the same machine. An inorganic anti-sticking agent (silica, as above) is added to the top surface extruder, with a weight ratio of anti-sticking agent to propylene polymer composition granules of 0.2:100. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film consisting of an upper surface layer (layer b) and a core layer (layer a). The film thickness is 50 μm, and the thickness ratio of layer b to layer a is 1:2.

[0770] Example G5 (using polypropylene-g-4-vinylpyridine)

[0771] I. Preparation of polypropylene-g-4-vinylpyridine

[0772] The basic copolymer polypropylene powder with the following characteristics was selected: ethylene content of comonomer 18.1 wt%, xylene-soluble content 48.7 wt%, comonomer content in soluble matter 31.9 wt%, soluble matter / copolymer polypropylene intrinsic viscosity ratio 0.89, and weight-average molecular weight 34.3 × 10⁻⁶. 4 The MFR (Mean Flow Rate) at 230℃ and 2.16kg load was 1.21g / 10min, Tm = 143.4℃, and fine powder smaller than 40 mesh was removed by sieving. 2.0kg of the above-mentioned basic copolymer polypropylene powder was weighed and added to a 10L reactor equipped with a mechanical stirrer. The reaction system was sealed, and nitrogen was used for purging to remove oxygen. 1.2g of benzoyl peroxide and 40g of 4-vinylpyridine were added, stirred and mixed for 30min, swelled at 50℃ for 30min, and then heated to 90℃ for 4 hours. After the reaction, nitrogen was used for purging and cooling to obtain polypropylene-g-4-vinylpyridine with a melt flow rate of 0.89g / 10min, M1 of 0.92%, and grafting efficiency of 47%.

[0773] II. Preparation of Composite Thin Films

[0774] (1) Used in the preparation of propylene polymer composition A:

[0775] Component a is homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical Co., Ltd., with a melt flow rate of 3.1 g / 10 min, isotacticity of 98%, and molecular weight distribution Mw / Mn of 4.7); component b is polypropylene-g-4-vinylpyridine prepared as above; and component c is polyolefin elastomer of grade 6102 (purchased from ExxonMobil, an ethylene-propylene copolymer). The components prepared above were weighed and mixed according to the specified proportions, wherein component a (W) had a mass fraction Wa of 75 parts by weight, component b (Wb) had a mass fraction Wb of 10 parts by weight, and component c (Wc) had a mass fraction Wc of 15 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, and based on a total mass of 100 parts by weight for components a, b, and c, the amount of lubricant added is 0.1 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of propylene polymer composition A are obtained. The melt flow rate (MFR) is then measured. A = 3.1g / 10min.

[0776] (2) Preparation of propylene polymer composition B:

[0777] Component x is a random copolymer of propylene, grade F5006 (purchased from Yanshan Petrochemical, an ethylene-propylene-butene terpolymer with a melt flow rate of 5.2 g / 10 min); component y is a polyolefin elastomer, grade 6102 (purchased from ExxonMobil, an ethylene-propylene copolymer). The components prepared above were weighed and mixed according to the specified ratio, wherein the mass fraction of component x, Wx, was 75 parts by weight, and the mass fraction of component y, Wy, was 25 parts by weight. The ratio of Wc to Wy was 3:5. Other steps were the same as in step (1), finally yielding granules of the propylene polymer composition B. The melt flow rate (MFR) of the granules was then tested. B = 3.2g / 10min.

[0778] (3) Preparation of composite films:

[0779] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the top surface extruder of the same machine. An inorganic anti-sticking agent (silica, as above) is added to the top surface extruder, with a weight ratio of anti-sticking agent to propylene polymer composition granules of 0.2:100. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film consisting of an upper surface layer (layer b) and a core layer (layer b). The film thickness is 50 μm, and the thickness ratio of layer b to layer a is 1:2.

[0780] Example G6 (using polypropylene-g-styrene prepared in Example G3)

[0781] (1) Preparation of propylene polymer composition A for preparing layer a:

[0782] Component a is a homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical Co., Ltd., with a melt flow rate of 3.1 g / 10 min, isotacticity of 98%, and molecular weight distribution Mw / Mn of 4.7); component b is a polyolefin elastomer of grade 6102 (purchased from ExxonMobil, an ethylene-propylene copolymer). The components prepared above were weighed and mixed according to the specified proportions, wherein component a (W) had a mass fraction Wa of 80 parts by weight, and component b (Wb) had a mass fraction Wb of 20 parts by weight. Then, a lubricant (a PEG lubricant manufactured by Clariant AG, Switzerland, with a molecular weight of 10,000, and 0.1 parts by weight based on a total mass of 100 parts by weight of components a and b) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws via the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of the propylene polymer composition A are obtained. The melt flow rate (MFR) is then measured. A = 3.5g / 10min.

[0783] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0784] Component x is a random copolymer of propylene, grade F5006 (purchased from Yanshan Petrochemical, an ethylene-propylene-butene terpolymer with a melt flow rate of 5.2 g / 10 min); component y is a polyolefin elastomer, grade 6102 (purchased from ExxonMobil, an ethylene-propylene copolymer); component z is the polypropylene-g-styrene prepared in Example G3. The components obtained above were weighed and mixed according to the specified ratio, wherein the mass fraction of component x (Wx) was 85 parts by weight, the mass fraction of component y (Wy) was 5 parts by weight, and the mass fraction of component z (Wz) was 10 parts by weight. The ratio of Wb to Wy was 4:1. Other steps were the same as in step (1), and finally, granules of the propylene polymer composition B were obtained. The melt flow rate (MFR) of the granules was then tested. B = 4.64g / 10min.

[0785] (3) Preparation of composite films:

[0786] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the top surface extruder of the same machine. An inorganic anti-sticking agent (silica, as above) is added to the top surface extruder, with a weight ratio of anti-sticking agent to propylene polymer composition granules of 0.2:100. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film consisting of an upper surface layer (layer b) and a core layer (layer a). The film thickness is 50 μm, and the thickness ratio of layer b to layer a is 1:2.

[0787] Example G7 (using polypropylene-g-styrene / maleic anhydride)

[0788] I. Preparation of polypropylene-g-styrene / maleic anhydride

[0789] The basic copolymer polypropylene powder with the following characteristics was selected: ethylene content of comonomer 18.1 wt%, xylene-soluble content 48.7 wt%, comonomer content in soluble matter 31.9 wt%, soluble matter / copolymer polypropylene intrinsic viscosity ratio 0.89, and weight average molecular weight 34.3 × 10⁻⁶. 4The MFR (Mean Flow Rate) at 230℃ and 2.16kg load was 1.21g / 10min, Tm = 143.4℃, and fine powder smaller than 40 mesh was removed by sieving. 2.0kg of the above-mentioned basic copolymer polypropylene powder was weighed and added to a 10L reactor equipped with a mechanical stirrer. The reaction system was sealed, and nitrogen was used for purging to remove oxygen. A solution of 1.3g benzoyl peroxide, 10g maleic anhydride, and 40g styrene was added, stirred and mixed for 30min, swelled at 40℃ for 2 hours, and then heated to 90℃ for 4 hours. After the reaction was completed, nitrogen was used for purging and cooling to obtain polypropylene-g-styrene / maleic anhydride with a melt flow rate of 0.71g / 10min, M1 of 1.27%, M2 of 0.44%, and grafting efficiency of 52%.

[0790] II. Preparation of Composite Thin Films

[0791] (1) Preparation of propylene polymer composition A for preparing layer a:

[0792] Component a is homopolymer polypropylene of grade PPH-FA03 (purchased from Qingdao Refining & Chemical Co., Ltd., melt flow rate 3.1 g / 10 min, isotacticity 98%, molecular weight distribution Mw / Mn 4.7); component b is polypropylene-g-styrene / maleic anhydride prepared as above; component c is polyolefin elastomer of grade 6102 (purchased from ExxonMobil, ethylene-propylene copolymer). The components prepared above were weighed and mixed according to the specified proportions, wherein component a (Wa) had a mass fraction of 75 parts by weight, component b (Wb) had a mass fraction of 10 parts by weight, and component c (Wc) had a mass fraction of 15 parts by weight. Then, a lubricant (PEG lubricant manufactured by Clariant AG, Switzerland, molecular weight 10000, and based on a total mass of 100 parts by weight for components a, b, and c, the amount of lubricant added is 0.1 parts by weight) is added. The mixture is then added to a high-speed mixer and mixed thoroughly. The mixed material is then fed into the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screws through the feeder. During processing, the screw temperature is maintained between 160-230°C. After being melted, mixed, extruded, granulated, and dried, granules of propylene polymer composition A are obtained. The melt flow rate (MFR) is then measured. A = 2.9g / 10min.

[0793] (2) Preparation of propylene polymer composition B used to prepare layer b:

[0794] Component x is random polypropylene of grade F5006 (purchased from Yanshan Petrochemical, an ethylene-propylene-butene terpolymer with a melt flow rate of 5.2 g / 10 min); component y is polyolefin elastomer of grade 6102 (purchased from ExxonMobil, an ethylene-propylene copolymer). The components obtained above were weighed and mixed according to the specified ratio, wherein the mass fraction of component x (Wx) was 75 parts by weight, and the mass fraction of component y (Wy) was 25 parts by weight. The ratio of Wc to Wy was 3:5. Other steps were the same as in step (1), and finally, granules of the propylene polymer composition B were obtained. The melt flow rate (MFR) was then measured. B = 3.2g / 10min.

[0795] (3) Preparation of composite films:

[0796] The propylene polymer composition A and propylene polymer composition B granules obtained in steps (1) and (2) above are dried. Then, propylene polymer composition A is added to the core extruder of a multilayer extrusion casting machine, and propylene polymer composition B is added to the top surface extruder of the same machine. An inorganic anti-sticking agent (silica, the same below) is added to the top surface extruder, and the weight ratio of the anti-sticking agent to the propylene polymer composition granules is 0.2:100. During the casting process, the temperature of the casting quench roll is set to 30°C, and the film is wound up to form a composite film consisting of an upper surface layer (layer b) and a core layer (layer a). The film thickness is 50 μm, and the thickness ratio of layer b to layer a is 1:2.

[0797] Table 9

[0798]

[0799] Note: - indicates not measured

[0800] As can be seen from the results in Table 9, adding polar monomers to modify polypropylene in the composite film of the present invention can achieve higher surface energy, thereby enabling the resulting composite film to have better adhesion to other materials. Adding propylene-grafted polymers can achieve higher volume resistivity, thus the resulting composite film exhibits better electrical insulation properties.

[0801] The present invention has been described above by way of example with reference to embodiments; however, the description is not exhaustive and is not intended to limit the scope of the invention. Many modifications and alterations will be apparent to those skilled in the art without departing from the scope and spirit of the invention.

[0802] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. Furthermore, different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the spirit of the present invention, and should also be considered as part of the disclosure of the present invention.

[0803] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A composite film based on propylene polymers comprising at least two different layers: layer a and layer b; wherein each of layer a and layer b comprises at least one propylene polymer; and at least one of layer a and layer b comprises a propylene impact copolymer; wherein the propylene impact copolymer comprises an elastomeric fraction which forms dispersed, strip-like rubber phases in the composite film, the rubber phases being arranged parallel to each other, and the average size of the transverse axes of the rubber phases being in the range of from 20 to 200 nm and the average value of the aspect ratio of the rubber phases being in the range of from 5 to 20, as determined by atomic force microscopy on a cross-section of the composite film cut in the transverse direction (TD); wherein the film haze of the composite film is less than 7%.

2. The composite film according to claim 1, wherein the average size of the transverse axes of the rubber phases is in the range of from 20 to 150 nm and the average value of the aspect ratio of the rubber phases is in the range of from 5 to 15, as determined by atomic force microscopy on a cross-section of the composite film cut in the transverse direction.

3. The composite film according to claim 1 or 2, characterized in that, the angle between the transverse cross-sections of the rubber phases is not more than 10 degrees, as determined by atomic force microscopy on a cross-section of the composite film cut in the transverse direction.

4. The composite film according to claim 1 or 2, characterized by, the elastomeric fraction appears as globular or near-globular rubber phases in a scanning electron micrograph of an impact bar of the propylene impact copolymer.

5. The composite film according to claim 1 or 2, wherein the propylene impact copolymer is a propylene impact copolymer containing ethylene units, wherein the elastomeric fraction is a copolymer fraction containing ethylene units.

6. The composite film according to claim 5, wherein the elastomeric fraction is selected from the group consisting of ethylene-propylene copolymer fractions and ethylene-butylene copolymer fractions.

7. The composite film of claim 5, wherein the propylene impact copolymer comprises a propylene homopolymer fraction and the copolymer fraction containing ethylene units; and / or the content of the copolymer fraction containing ethylene units in the propylene impact copolymer is in the range of from 3 to 15 wt.%; and / or the content of ethylene units in the propylene impact copolymer is in the range of from 1 to 14 wt.%, based on the total weight of the propylene impact copolymer; and / or, the content of ethylene units in the room temperature xylene-soluble fraction of the propylene impact copolymer is not more than 40 wt.%; and / or, The content of ethylene unit groups [EEE] in the room temperature xylene soluble fraction of the propylene impact copolymer is not more than 20 wt.%, determined by 13 C NMR determination; and / or, the melt mass flow rate of the propylene impact copolymer is in the range of from 1 to 10 g / 10 min at 230°C under a load of 2.16 kg.

8. The composite film according to claim 1 or 2, wherein both layer a and layer b comprise the propylene impact copolymer, wherein the propylene impact copolymer in layer a and layer b is the same or different; or only one of layer a and layer b contains the propylene impact copolymer.

9. The composite film according to claim 1 or 2, wherein at least one of layer a and layer b comprises a polyolefin elastomer.

10. The composite film of claim 9, wherein The polyolefin elastomer is an elastomeric copolymer of ethylene and an alpha olefin, wherein the alpha olefin is a C3-C 12 alpha olefin.

11. The composite film of claim 10, wherein the alpha-olefin is selected from at least one of propylene, 1-butene, 1-hexene and 1-octene.

12. The composite film of claim 9, wherein the polyolefin elastomer has a ratio of shear viscosities, η -1 / η -1 at 230°C, shear rate 160 s 160 -1 and 640 s 640 -1, of 1.2 to 3; and / or, The polyolefin elastomer was subjected to a shear rate of 640 s at 230 °C. -1 The shear viscosity η 640 The shear viscosity is 100-500 Pa·s, and the shear viscosity is determined by a capillary rheometer according to ISO 11443:2014.

13. The composite film of claim 9, wherein the elastomeric fraction in the propylene impact copolymer and the polyolefin elastomer form dispersed rubber phases in the composite film, the rubber phases being in the form of strips, the average size of the transverse axes of the rubber phases being in the range of from 20 to 200 nm; and the average value of the aspect ratio of the rubber phases being in the range of from 5 to 20, as determined by atomic force microscopy on a cross-section of the composite film cut in the transverse direction.

14. The composite film according to claim 9, wherein both layer a and layer b comprise the polyolefin elastomer, wherein the polyolefin elastomer in layer a and layer b is the same or different; or Only one of the layers a and b contains the polyolefin elastomer.

15. The composite film of claim 14, wherein, The ratio between the proportion by weight of the polyolefin elastomer in layer a and the proportion by weight of the polyolefin elastomer in layer b is from 6:1 to 1:

6.

16. The composite film according to claim 1 or 2, wherein Layer a comprises a homopolymer polypropylene and / or a propylene random copolymer.

17. The composite film of claim 16, wherein, The homopolymer polypropylene has a melt mass flow rate at 230 °C under a load of 2.16 kg of from 2 to 15 g / 10 min; and / or, The homopolymer polypropylene has an isotacticity of more than 97%; and / or, The homopolymer polypropylene has a molecular weight distribution Mw / Mn of from 4.5 to 7.

0.

18. The composite film according to claim 16, characterized in that The propylene random copolymer is selected from at least one of an ethylene-propylene-butylene ter random copolymer, a propylene-ethylene binary random copolymer, a propylene-butylene binary random copolymer; and / or, The propylene random copolymer has a melt mass flow rate at 230 °C under a load of 2.16 kg of from 2 to 15 g / 10 min; and / or, The propylene random copolymer has a molecular weight distribution Mw / Mn of from 4.5 to 7.

0.

19. The composite film according to claim 1 or 2, wherein Layer b comprises a propylene random copolymer.

20. The composite film according to claim 19, characterized in that The propylene random copolymer is selected from at least one of an ethylene-propylene-butylene ter random copolymer, a propylene-ethylene binary random copolymer, a propylene-butylene binary random copolymer; and / or, The propylene random copolymer has a melt mass flow rate at 230 °C under a load of 2.16 kg of from 2 to 15 g / 10 min; and / or, The propylene random copolymer has a molecular weight distribution Mw / Mn of from 4.5 to 7.

0.

21. The composite film of claim 19, wherein Layer a comprises a polyolefin elastomer, the propylene impact copolymer and a further propylene polymer selected from a homopolymer polypropylene and / or a propylene random copolymer; and layer b comprises a propylene random copolymer and a polyolefin elastomer.

22. The composite film according to claim 21, characterized in that Layer a comprises from 40 to 90 wt.-% of the propylene impact copolymer, from 5 to 40 wt.-% of the further propylene polymer and from 2 to 30 wt.-% of the polyolefin elastomer, based on the total weight of layer a; and and Layer b comprises from 40 to 95 wt.-% of the propylene random copolymer and from 5 to 60 wt.-% of the polyolefin elastomer, based on the total weight of layer b.

23. The composite film of claim 19, wherein, Layer a comprises a homopolymer polypropylene, the propylene impact copolymer and a polyolefin elastomer and layer b comprises a propylene random copolymer and a polyolefin elastomer.

24. The composite film according to claim 23, characterized in that The ratio between the proportion by weight of the polyolefin elastomer in layer a and the proportion by weight of the polyolefin elastomer in layer b is from 2:1 to 1:4; and / or Layer a comprises from 40 to 90 wt.-% of the homopolymer polypropylene, from 5 to 40 wt.-% of the propylene impact copolymer and from 2 to 30 wt.-% of the polyolefin elastomer, based on the total weight of layer a; and and layer b comprises from 40 to 95 wt.-% of the propylene random copolymer and from 5 to 60 wt.-% of the polyolefin elastomer, based on the total weight of layer b.

25. The composite film according to claim 24, wherein, a ratio between a weight proportion of the polyolefin elastomer in layer a and a weight proportion of the polyolefin elastomer in layer b is 1:1-1:

2.

26. The composite film of claim 19, wherein layer a comprises a propylene polymer selected from homopolymer polypropylene and / or the propylene impact copolymer and a polyolefin elastomer; and layer b comprises a propylene random copolymer, a polyolefin elastomer and the propylene impact copolymer.

27. The composite film according to claim 26, wherein, a ratio between a weight proportion of the polyolefin elastomer in layer a and a weight proportion of the polyolefin elastomer in layer b is 6:1-1:4; and / or layer a comprises 50-95 wt% of the propylene polymer and 5-50 wt% of the polyolefin elastomer, based on the total weight of layer a; and layer b comprises 40-90 wt% of the propylene random copolymer, 5-40 wt% of the polyolefin elastomer and 2-30 wt% of the propylene impact copolymer, based on the total weight of layer b.

28. The composite film of claim 1 or 2, wherein, layer a and / or layer b further comprises an additive selected from at least one of an antioxidant, a lubricant, an anti-halogen agent, a light stabilizer, a heat stabilizer, a colorant, a filler, a slip agent, an anti-blocking agent, a surface adhesion agent, an electromagnetic shielding aid, a flame retardant, an insulation additive and an antistatic agent.

29. The composite film according to claim 28, wherein, the antioxidant is selected from at least one of antioxidant 1076, antioxidant 1010, antioxidant 168 and a sulfur ester antioxidant; and / or, the lubricant is a PEG-based lubricant and / or a monoglyceride-based lubricant; and / or, the filler is at least one electrically conductive filler selected from carbon black, graphite, carbon nanotube, carbon fiber, electrically conductive metal particle, electrically conductive metal fiber, electrically conductive metal-coated filler and metal oxide; and / or, the electromagnetic shielding aid is an electrically conductive metal filler and / or a carbon material; wherein the electrically conductive metal filler is electrically conductive metal particle and / or electrically conductive metal fiber; the carbon material is one or more of carbon black, graphite, graphene and carbon nanotube; and / or, the flame retardant is selected from at least one of phosphorus-based flame retardant, boron-based flame retardant and antimony-based flame retardant; and / or, the colorant is selected from at least one of azo pigment, phthalocyanine pigment, dye, fluorescent whitening agent and fluorescent pigment; and / or the slip agent is selected from an amide-based slip agent or a mixture of an amide-based slip agent and a migration-resistant slip agent, wherein the amide-based slip agent is at least one of erucic acid amide, oleic acid amide, stearic acid amide, behenic acid amide, stearyl erucic acid amide and ethylene bis-stearamide, and the migration-resistant slip agent is at least one of polytetrafluoroethylene microparticle, polyimide microparticle, polyamide microparticle, polycarbonate microparticle, silicone, nano calcium carbonate, mica and nano silicon dioxide.

30. The composite film of claim 28, wherein, the flame retardant is a hydrate of a metal or non-metal hydroxide and / or oxide.

31. The composite film of claim 28, wherein, the flame retardant is an intumescent flame retardant.

32. The composite film of claim 28, wherein, the colorant is a heterocyclic pigment.

33. The composite film of claim 28, wherein, the colorant is a lake pigment.

34. The composite film of claim 28, wherein, The content of the antioxidant is 0.1 to 0.8 parts by weight based on 100 parts by weight of the total weight of the layer.

35. The composite film of claim 28, wherein, The content of the lubricant is 0.01 to 0.5 parts by weight based on 100 parts by weight of the total weight of the layer.

36. The composite film of claim 29, wherein, The conductive filler is added in layer b in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the total weight of the base polymer in layer b.

37. The composite film of claim 28, wherein, The electromagnetic shielding aid is added in layer b in an amount of 5 to 30 parts by weight based on 100 parts by weight of the base polymer in layer b.

38. The composite film of claim 28, wherein, The electromagnetic shielding aid is used in combination with a titanate-based coupling agent.

39. The composite film of claim 28, wherein, The flame retardant is added in a layer other than layer a and layer b.

40. The composite film of claim 28, wherein, The colorant is added in layer a.

41. The composite film of claim 29, wherein, A slip agent is added in both layer a and layer b, wherein an amide-based slip agent is added in layer a, and a mixture of an amide-based slip agent and a transfer-resistant slip agent is added in layer b.

42. The composite film of claim 28, wherein, The surface adhesive is a polar monomer-modified polypropylene, wherein the polar monomer is selected from at least one of a hydroxyl group-containing comonomer, a cyano group-containing comonomer, and an acid anhydride monomer.

43. The composite film of claim 42, wherein, The polar monomer is selected from a hydroxy acid, a vinyl alcohol, a cyano acrylate, a maleic anhydride, and an itaconic anhydride.

44. The composite film of claim 42, wherein, The polar monomer-modified polypropylene is added in layer b in an amount of 1 to 30 wt% based on the total weight of layer b.

45. The composite film of claim 28, wherein, The insulation additive is a propylene graft polymer.

46. The composite film of claim 45, wherein, The insulation additive is added in layer a and / or layer b in an amount of 5 to 45 wt% based on the total weight of the layer.

47. The composite film of claim 45, wherein, The propylene graft polymer comprises structural units derived from a copolypropylene and structural units derived from grafting monomers selected from the group consisting of: acrylate-based; acrylic-based; styrene-based; alkenyl group-containing silane-based; alkenyl group-containing heterocyclic-based monomers; acid anhydride having at least one olefinic unsaturation; and alkenyl group-containing polymeric monomers.

48. The composite film of claim 47, wherein, The propylene graft polymer is prepared by a solid phase grafting reaction of a copolypropylene with grafting monomers; and / or The comonomer other than propylene in the copolypropylene is selected from at least one of ethylene and C4-C8 α-olefins; and / or The copolymerized polypropylene has at least one of the following characteristics: a comonomer content of 0.5 to 30 mol%; a xylene solubles content of 2 to 80 wt%; a comonomer content in the solubles of 10 to 70 wt%; a ratio of the intrinsic viscosity of the solubles to the copolymerized polypropylene of 0.3 to 5; a melt mass flow rate at 230°C under a load of 2.16 kg of 0.01 to 60 g / 10 min; a melting temperature Tm of 100°C or more; a weight average molecular weight of 20 x 10 4 - 60 x 10 4 g / mol; and / or, The propylene graft polymer has a melt mass flow rate of 0.01 to 30 g / 10 min at 230°C under a load of 2.16 kg.

49. The composite film of claim 48, wherein, The copolypropylene has a melting temperature Tm of 110 to 180°C.

50. The composite film according to claim 45, wherein The propylene graft polymer comprises structural units derived from a copolypropylene and structural units derived from grafting onto the copolypropylene acrylate-based monomers and optionally acrylic-based monomers; wherein the content of the structural units derived from grafting onto the copolypropylene acrylate-based monomers and optionally acrylic-based monomers is 0.3 to 7 wt% based on the weight of the propylene graft polymer; and the molar ratio of the structural units derived from acrylate-based monomers to the structural units derived from acrylic-based monomers in the propylene graft polymer is 1:0 to 2; or The propylene graft polymer comprises structural units derived from the copolymerized polypropylene and structural units derived from a styrene-based monomer; the content of the structural units derived from the graft of the styrene-based monomer in the propylene graft polymer is 0.5-14% by weight; or, The propylene graft polymer comprises structural units derived from the copolymerized polypropylene and structural units derived from an alkenyl-containing silane-based monomer; wherein the content of the structural units derived from the graft of the alkenyl-containing silane-based monomer in the propylene graft polymer b is 0.2-6% by weight; or, The propylene graft polymer comprises structural units derived from the copolymerized polypropylene, structural units derived from an anhydride monomer, and structural units derived from an alkenyl-containing polymerized monomer; the alkenyl-containing polymerized monomer is selected from at least one of vinyl acetate, styrene, α-methyl styrene, (meth)acrylate, vinyl alkyl ether, vinyl pyrrolidone, vinyl pyridine, vinyl imidazole, and acrylonitrile; the anhydride is selected from maleic anhydride and / or itaconic anhydride; the content of the structural units derived from the graft of the anhydride monomer and the alkenyl-containing polymerized monomer is 0.1-5% by weight; and / or, the content of the structural units derived from the graft of the anhydride monomer is 0.05-2% by weight; and / or, the molar ratio of the structural units derived from the anhydride monomer to the structural units derived from the alkenyl-containing polymerized monomer is 1:1-20; or, The propylene graft polymer comprises structural units derived from the copolymerized polypropylene and structural units derived from an alkenyl-containing heterocyclic monomer; the content of the structural units derived from the graft of the alkenyl-containing heterocyclic monomer is 0.5-6% by weight based on the weight of the propylene graft polymer.

51. The composite film of claim 50, wherein, The molar ratio of the structural units derived from the acrylate monomer to the structural units derived from the acrylic monomer in the propylene graft polymer is 1:0.125-1.

52. The composite film according to claim 1 or 2, wherein The propylene polymer composition A used for forming layer a has a melt mass flow rate of 2-10 g / 10 min at 230°C under a load of 2.16 kg; and / or The propylene polymer composition B used for forming layer b has a melt mass flow rate of 2-10 g / 10 min at 230°C under a load of 2.16 kg.

53. The composite film of claim 1 or 2, wherein, The difference between the shear viscosities of the propylene polymer composition A for constituting layer a and the propylene polymer composition B for constituting layer b at 230 °C, shear rate 160 s -1 -1, i.e. ηA 160 - ηB 160 , and at 230 °C, shear rate 640 s -1 -1, i.e. ηA 640 - ηB 640 , are both > 0, and the ratio of the two (ηA 160 - ηB 160 ) / (ηA 640 - ηB 640 ) is 1-2.6, said shear viscosities being determined according to ISO 11443:2014, using a capillary rheometer; wherein the shear viscosities of the propylene polymer composition A at shear rates of 160 s -1 and 640 s -1 are denoted ηA 160 and ηA 640 , respectively, and the shear viscosities of the propylene polymer composition B at shear rates of 160 s -1 and 640 s -1 are denoted ηB 160 and ηB 640 , respectively.

54. The composite film of claim 1 or 2, wherein, The composite film further comprises one or more additional layers, and layer b is the surface layer of the composite film, wherein the composition of the additional layer is the same as or different from that of layer a or layer b.

55. The composite film of claim 54, wherein, The composite film is a three-layer film, and the additional layer is referred to as layer c, and layer b and layer c are respectively located on both sides of layer a.

56. The composite film of claim 53, wherein, The ratio of the sum of the thicknesses of the layers other than layer a to the thickness of layer a in the composite film is 1:6-2:

1.

57. The composite film of claim 56, wherein, The ratio of the sum of the thicknesses of the layers other than layer a to the thickness of layer a in the composite film is 1:4-2:

1.

58. The composite film of claim 56, wherein, The ratio of the sum of the thicknesses of the layers other than layer a to the thickness of layer a in the composite film is 1:2-1:

1.

59. The composite film of claim 1 or 2, wherein, The composite film has one or more of the following properties: 1) a pendulum impact strength of > 0.4 J; 2) a film haze of < 5%; 3) a machine direction tensile strength of > 40 MPa; 4) a heat seal strength at 150°C of > 12 N / 15 mm; 5) a thickness deviation in the MD direction of not more than 1.3; 6) a thickness deviation in the TD direction of not more than 1.5; 7) a deviation in the impact resistance in the MD direction of not more than 0.05; 8) a deviation in the impact resistance in the TD direction of not more than 0.07; 9) a surface energy of > 29 mN / m; 10) volume resistivity > 1.5 x 10 15 Ω-m.

60. A process for producing a composite film according to any one of claims 1 to 59, comprising: extrusion casting the composite film from a raw material composition used for forming the respective layers after an optional granulation process, wherein prior to the extrusion process, the elastomeric fraction of the propylene impact copolymer used in the raw material composition forms a particulate rubber phase having an average particle size of less than or equal to 1.8 μm and a maximum particle size of not more than 2.5 μm, as determined by scanning electron microscopy of the impact bar fracture surface.

61. The method of claim 60, wherein, the elastomeric fraction of the propylene impact copolymer used in the raw material composition forms a spherical or near-spherical rubber phase.

62. The method of claim 60 or 61, wherein, the process further comprises stretching the resulting composite film.

63. The method of claim 62, wherein, the process further comprises biaxially stretching the resulting composite film.

64. Use of a composite film according to any one of claims 1 to 59 or obtained by a process according to any one of claims 60 to 63 in the field of packaging materials.

65. Use according to claim 64, wherein the packaging material is a battery packaging material or a food packaging material.

66. Use according to claim 65, wherein the packaging material is an electronics packaging material.

67. A packaging material comprising a composite film according to any one of claims 1 to 59 or obtained by a process according to any one of claims 60 to 63.

68. A packaging material according to claim 67, wherein the packaging material is a battery packaging material or a food packaging material.

69. A packaging material according to claim 68, wherein the packaging material is an electronics packaging material.

70. A packaging material according to claim 68, wherein the packaging material comprises an aluminum laminate.

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