Polypropylene film and polypropylene decorative film

Abstract

The invention discloses a polypropylene film and a polypropylene decorative film, the polypropylene film comprises a printing surface layer, the printing surface layer comprises the following raw materials by weight: 46-65 parts of polypropylene; 4 to 10 parts of grafted polypropylene; 8-25 parts of a polar ethylene copolymer; the vicat softening point temperature of the polypropylene is 100-125 DEG C; and the Vicat softening point temperature of the printing surface layer is 90-110 DEG C. Therefore, the polypropylene film provided by the invention has excellent ink adhesive force, and especially can keep good ink adhesive force after being attached to a transparent mask at a high temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of plastic films, and in particular relates to a polypropylene film and a polypropylene decorative film. Background Art

[0002] At present, the main finishing materials of decorative panels are melamine impregnated paper, PVC and paint. Both impregnated paper and paint contain volatile small molecules, which will release free formaldehyde during the manufacturing and use process. As people pay more attention to environmental protection and health, the pollution and harm of free formaldehyde have attracted much attention. PVC itself contains chlorine and plasticizers, which will also harm human health and cause environmental pollution.

[0003] With the society's concern about environmental safety and people's emphasis on health, products such as decorative panels and their raw materials are also turning towards green, environmentally friendly and high-performance. Polypropylene is a polymer with high temperature resistance, good toughness and strong chemical corrosion resistance. It does not contain harmful substances such as chlorine, formaldehyde, heavy metals, etc. It has excellent comprehensive performance. It is the most promising thermoplastic polymer material today and one of the preferred materials for environmentally friendly decorative films. However, polypropylene itself is a non-polar polymer, and it is difficult to print ink on the surface. Although it has been corona treated, the polypropylene surface can be printed with ink. However, after the printed product is pasted with a transparent mask at high temperature, the ink adhesion on the polypropylene surface will be significantly reduced. When testing the adhesion between the mask and the polypropylene film, the printed ink will easily peel off the polypropylene film, and the methods for improving the adhesion between the polypropylene film and the ink in the prior art do not involve the adhesion performance of the polypropylene film with the ink after the transparent mask is pasted with a high-temperature heat. Therefore, it is urgent to improve the ink adhesion of the polypropylene film, especially the ink adhesion ability of the polypropylene film after the transparent mask is pasted with a high-temperature heat. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art to a certain extent. To this end, the present invention provides a polypropylene film and a polypropylene decorative film, wherein the polypropylene film of the present invention can still have good ink adhesion after being treated with a transparent mask at high temperature.

[0005] Therefore, in the first aspect of the present invention, the present invention provides a polypropylene film, the polypropylene film includes a printed surface layer, and the printed surface layer includes the following raw materials in parts by weight:

[0006] Polypropylene 46-65 parts;

[0007] 4-10 parts of grafted polypropylene;

[0008] 8-25 parts of polar ethylene copolymer;

[0009] The Vicat softening point of polypropylene is 100-125°C; the Vicat softening point of the printed surface is 90-110°C.

[0010] According to the embodiment of the present invention, after the polypropylene film is printed with ink and attached to a transparent mask at high temperature, the peeling force between the ink and the printed surface layer can reach more than 5N / cm. Therefore, the polypropylene film of the present invention has excellent ink adhesion, especially can maintain good ink adhesion after being attached to a transparent mask at high temperature.

[0011] In some embodiments, the polypropylene includes at least one of terpolymer polypropylene and random copolymer polypropylene.

[0012] In some embodiments, the grafted polypropylene satisfies at least one of the following:

[0013] (1) The grafting rate of grafted polypropylene is 1 to 1.5%;

[0014] (2) The Vicat softening point of grafted polypropylene is 95-110°C;

[0015] (3) The grafting monomer of the grafted polypropylene contains a carbonyl functional group.

[0016] In some embodiments, the polar ethylene copolymer satisfies at least one of the following:

[0017] (A) the polar ethylene copolymer comprises a carbonyl functional group;

[0018] (B) The polar ethylene copolymer is formed by polymerization of polar monomers and ethylene, wherein the content of the polar monomers in the reactants of the polymerization reaction is 18-28%.

[0019] In some embodiments, the printed surface layer further comprises the following raw materials in parts by weight:

[0020] 8-15 parts of alpha olefin copolymer;

[0021] 2 to 8 parts of filler;

[0022] Anti-aging agent 0.05 to 1 part.

[0023] In some embodiments, the printed surface layer satisfies at least one of the following:

[0024] (a) the α-olefin copolymer comprises at least one of an ethylene-α-olefin copolymer and a propylene-α-olefin copolymer;

[0025] (b) the Vicat softening point temperature of the α-olefin copolymer is 50 to 70°C;

[0026] (c) the filler comprises at least one of aluminum oxide, calcium carbonate, magnesium carbonate, aluminum sulfate, barium sulfate, aluminum silicate, magnesium silicate, titanium dioxide, and silicon dioxide;

[0027] (d) The anti-aging agent includes at least one of an antioxidant, an ultraviolet absorber, a light stabilizer and a free radical quencher.

[0028] In some embodiments, the polypropylene film further includes an intermediate layer and a composite surface layer, wherein the intermediate layer is located between the printed surface layer and the composite surface layer.

[0029] In some embodiments, the middle layer includes the following raw materials in parts by weight: polyolefin, 74 to 90 parts by weight; filler, 9 to 25 parts by weight; anti-aging agent, 0.5 to 3 parts by weight.

[0030] In some embodiments, the composite surface layer includes the following raw materials in parts by weight: polyolefin, 65 to 89 parts by weight; alpha-olefin copolymer, 10 to 30 parts by weight; filler, 0 to 8 parts by weight; anti-aging agent, 0.2 to 1.5 parts by weight.

[0031] In the second aspect of the present invention, the present invention provides a polypropylene decorative film, comprising the polypropylene film of the first aspect. Thus, the printing ink in the polypropylene decorative film has good adhesion to the polypropylene film, thereby increasing the stability of the product.

[0032] Compared with the prior art, the present invention has the following beneficial technical effects:

[0033] (1) The present invention provides a resin system for polypropylene film, wherein polar ethylene copolymer and grafted polypropylene are added as adhesive resins, and alpha olefin copolymer is added to improve the compatibility of the system, and the amount of polypropylene in the formula system is greater than 50% of the total amount. The printed surface layer of the polypropylene film has good ink adhesion and good interlayer bonding strength;

[0034] (2) The present invention uses polypropylene with a Vicat softening point temperature between 100 and 125°C to adjust the resin system so that the Vicat softening point temperature of the printed surface layer is 90 to 110°C, thereby ensuring that the polypropylene film still has good ink adhesion after the heat-bonded mask is completed.

[0035] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0037] Figure 1 It is a schematic diagram of the structure of the polypropylene film of the present invention;

[0038] Figure 2This is a schematic diagram of the structure of a polypropylene film containing a printed pattern of the present invention;

[0039] Figure 3 It is a schematic diagram of the structure of the polypropylene decorative film containing a functional coating or a transparent mask of the present invention;

[0040] Among them, 1-printed surface layer; 2-intermediate layer; 3-composite surface layer; 4-printed pattern; 5-functional coating or transparent mask. DETAILED DESCRIPTION

[0041] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0042] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0043] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0044] In this document, the terms “include” or “comprising” are open expressions, that is, including the contents specified in the present invention but not excluding other contents.

[0045] In a first aspect of an embodiment of the present invention, the present invention provides a polypropylene film, the polypropylene film includes a printed surface layer, and the printed surface layer includes the following raw materials in parts by weight:

[0046] Polypropylene 46-65 parts;

[0047] Grafted polypropylene 4-10 parts;

[0048] 8-25 parts of polar ethylene copolymer;

[0049] The Vicat softening point of polypropylene is 100-125°C; the Vicat softening point of the printed surface is 90-110°C.

[0050] The rigidity of the polypropylene used in the present invention is relatively small, and the small rigidity is beneficial to prevent the printing ink from being easily peeled off from the polypropylene film after the polypropylene film is processed by ink printing and high-temperature bonding transparent mask. The Vicat softening point temperature of polypropylene is 100-125°C, and its melting point is low and has certain heat resistance. It can maintain a good surface state when used at room temperature. In the production of polypropylene decorative film, when the bonding process is carried out, the bonding processing temperature is generally 110-150°C. Therefore, the use of this kind of polypropylene can maintain the printed surface in a state of softening but not melting during the hot bonding process, thereby ensuring the good bonding performance of the polypropylene film and the printing ink. Adding grafted polypropylene to the printed surface layer can enhance the compatibility of polypropylene with other components in the printed surface layer, and at the same time increase the adhesion of the printed surface layer to the ink. Adding polar ethylene copolymers can effectively improve the polarity of polypropylene and ensure that the printed surface layer has excellent ink adaptability.

[0051] The inventors found that when the Vicat softening temperature of the printed surface is too high, the stress matching degree between the ink and the printed surface will decrease during the thermal bonding process, which will cause the printed ink to easily fall off the printed surface during the subsequent peeling test. Therefore, in the formulation design of the printed surface, it is necessary to ensure that the Vicat softening point temperature measured by the formulation is 90-110°C.

[0052] Therefore, the polypropylene film of the present invention has excellent ink adhesion, and can especially maintain good ink adhesion after being attached to a transparent mask at high temperature.

[0053] In some embodiments of the present invention, the polypropylene includes at least one of terpolymer polypropylene and random copolymer polypropylene.

[0054] Polypropylene materials are generally divided into homopolymer polypropylene and copolymer polypropylene, and copolymer polypropylene includes block copolymer polypropylene, wherein homopolymer polypropylene and block copolymer polypropylene are characterized by greater rigidity, higher melting point, and higher softening point temperature, which can generally reach above 150°C. The inventors have discovered that using this material in the printed surface layer will cause the printed surface layer to be too rigid, which will cause the film to be easily peeled off from the polypropylene film when the peeling force between the mask and the polypropylene film is tested after the film is printed and treated with a high-temperature transparent mask. However, the terpolymer polypropylene and random copolymer polypropylene in the copolymer polypropylene have relatively low rigidity, low melting point and certain heat resistance, and can maintain a good surface state when used at room temperature. Therefore, the use of terpolymer polypropylene and / or random copolymer polypropylene can maintain the printed surface layer in a state that begins to soften but does not melt during the thermal bonding process, thereby ensuring good bonding performance between the polypropylene film and the printing ink.

[0055] In some embodiments of the present invention, the grafted polypropylene satisfies at least one of the following:

[0056] (1) The grafting rate of grafted polypropylene is 1 to 1.5%;

[0057] (2) The Vicat softening point of grafted polypropylene is 95-110°C;

[0058] (3) The grafting monomer of the grafted polypropylene contains a carbonyl functional group.

[0059] When the grafting rate of grafted polypropylene is 1-1.5%, it can not only modify the polypropylene, but also avoid the degradation of polypropylene, so that it has a good use effect in the printed surface layer. The grafted monomer includes a carbonyl functional group, and the grafting polarity is higher, which can more easily form intermolecular forces with the printing ink, thereby increasing the adhesion between the printed surface layer and the ink.

[0060] As an example, the grafting monomer includes maleic anhydride.

[0061] In some embodiments of the present invention, the polar ethylene copolymer satisfies at least one of the following:

[0062] (A) the polar ethylene copolymer comprises a carbonyl functional group;

[0063] (B) The polar ethylene copolymer is formed by polymerization of polar monomers and ethylene, wherein the content of the polar monomers in the reactants of the polymerization reaction is 18-28%.

[0064] The use of ethylene copolymers containing carbonyl groups improves the polarity of the printed surface layer and makes the printed surface layer have excellent ink adaptability. When the content of polar monomers in the reactants is 18-28%, it is ensured that the content of polar groups in the formulation of the printed surface layer can meet the bonding requirements of the printing ink, and is also beneficial to the compatibility of the polar ethylene copolymer in the system and the interlayer fastness of the printed surface layer and the middle layer. Therefore, the polypropylene film of the present invention has excellent ink adhesion, especially can maintain good ink adhesion after high temperature bonding of transparent mask.

[0065] As an example, the ethylene copolymer includes at least one of ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-methyl acrylate copolymer (EMA).

[0066] In some embodiments of the present invention, the printed surface layer further comprises the following raw materials in parts by weight:

[0067] 8-15 parts of alpha olefin copolymer;

[0068] 2 to 8 parts of filler;

[0069] Anti-aging agent 0.05 to 1 part.

[0070] Alpha olefin copolymer is a copolymer material with many branches, which has good compatibility with polypropylene and polar ethylene copolymer, and plays the role of compatibilizer. Fillers can improve the coverage of polypropylene film and shield ultraviolet light, thereby increasing the service life of polypropylene film. At the same time, the raw materials of fillers are widely available and easy to obtain, which can reduce production costs. Anti-aging agents can prevent the aging of polypropylene film and extend its service life.

[0071] In some embodiments of the present invention, the printed surface layer satisfies at least one of the following:

[0072] (a) the α-olefin copolymer comprises at least one of an ethylene-α-olefin copolymer and a propylene-α-olefin copolymer;

[0073] (b) the Vicat softening point temperature of the α-olefin copolymer is 50 to 70°C;

[0074] (c) the filler comprises at least one of aluminum oxide, calcium carbonate, magnesium carbonate, aluminum sulfate, barium sulfate, aluminum silicate, magnesium silicate, titanium dioxide, and silicon dioxide;

[0075] (d) The anti-aging agent includes at least one of an antioxidant, an ultraviolet absorber, a light stabilizer and a free radical quencher.

[0076] In some embodiments of the present invention, the polypropylene film further comprises an intermediate layer and a composite surface layer, wherein the intermediate layer is located between the printed surface layer and the composite surface layer (eg Figure 1 shown).

[0077] In some embodiments of the present invention, the middle layer comprises the following raw materials in parts by weight: polyolefin, 74 to 90 parts by weight; filler, 9 to 25 parts by weight; anti-aging agent, 0.5 to 3 parts by weight.

[0078] In some embodiments of the present invention, the intermediate layer satisfies at least one of the following:

[0079] (1) The polyolefin comprises at least one of homopolypropylene, block polypropylene and random polypropylene, wherein the polypropylene content accounts for more than 85% of the total amount of the polyolefin, and may also contain other polyolefin resins such as high-density polyethylene, low-density polyethylene, linear low-density polyethylene, metallocene polyethylene, etc.;

[0080] (2) The filler includes at least one of aluminum oxide, calcium carbonate, magnesium carbonate, aluminum sulfate, barium sulfate, aluminum silicate, magnesium silicate, titanium dioxide, and silicon dioxide;

[0081] (3) The anti-aging agent includes at least one of an antioxidant, an ultraviolet absorber, a light stabilizer and a free radical quencher.

[0082] In some embodiments of the present invention, the composite surface layer includes the following raw materials in parts by weight: polyolefin, 65 to 89 parts by weight; alpha olefin copolymer, 10 to 30 parts by weight; filler, 0 to 8 parts by weight; anti-aging agent, 0.2 to 1.5 parts by weight.

[0083] In some embodiments of the present invention, the composite skin layer satisfies at least one of the following:

[0084] (A) the polyolefin comprises at least one of homopolypropylene, block polypropylene and random polypropylene, wherein the polypropylene content accounts for more than 85% of the total amount of the polyolefin, and may also contain other polyolefin resins such as high-density polyethylene, low-density polyethylene, linear low-density polyethylene, metallocene polyethylene, etc.;

[0085] (B) the α-olefin copolymer includes at least one of an ethylene-α-olefin copolymer and a propylene-α-olefin copolymer;

[0086] (C) the filler comprises at least one of aluminum oxide, calcium carbonate, magnesium carbonate, aluminum sulfate, barium sulfate, aluminum silicate, magnesium silicate, titanium dioxide, and silicon dioxide;

[0087] (D) The anti-aging agent includes at least one of an antioxidant, an ultraviolet absorber, a light stabilizer and a free radical quencher.

[0088] In some embodiments of the present invention, the method for preparing the polypropylene film includes a multi-layer co-extrusion process; the multi-layer co-extrusion process includes: mixing raw materials for preparing the polypropylene film and then performing a multi-layer co-extrusion process to obtain the polypropylene film.

[0089] The method is simple, convenient, easy to implement and easy to industrialize. The specific process conditions and parameters of the multi-layer co-extrusion process can adopt the process conditions and parameters of the multi-layer co-extrusion process known in the art.

[0090] In a second aspect of the embodiment of the present invention, the present invention provides a polypropylene decorative film, comprising the polypropylene film of the first aspect. Thus, the printing ink in the polypropylene decorative film has good adhesion to the polypropylene film, thereby increasing the stability of the product.

[0091] In some embodiments of the present invention, the polypropylene decorative film includes at least one of a pattern, a functional coating, and a transparent mask (such as Figure 2 and Figure 3 shown).

[0092] In some embodiments of the present invention, the method of printing the pattern includes multi-color overprinting.

[0093] In some embodiments of the present invention, the coating method of the functional coating includes gravure coating.

[0094] In some embodiments of the present invention, the method of laminating the transparent mask includes high-temperature lamination.

[0095] The scheme of the present invention will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are not indicated by the manufacturer and are all conventional products that can be obtained commercially.

[0096] Example 1

[0097] The raw materials for preparing the polypropylene film are mixed by three T-die extruders using a casting method and then subjected to multi-layer co-extrusion treatment to obtain a polypropylene film having a printed surface layer, an intermediate layer and a composite surface layer.

[0098] The printed surface layer is composed of 56 parts by weight of random polypropylene (Vicat softening point temperature 118°C, melt index 7g / 10min, 230°C / 2.16kg), 8 parts by weight of grafted polypropylene (grafting rate 1.0%, Vicat softening point temperature 100°C), 21.5 parts by weight of polar ethylene copolymer (EMA, MA content 22wt%), 12 parts by weight of ethylene-propylene copolymer (ethylene content 6%), 2 parts by weight of filler (titanium dioxide), and 0.5 parts by weight of anti-aging agent (antioxidant 1010). The Vicat softening point temperature of the printed surface layer is 99°C.

[0099] The middle layer is 80 parts by weight of polyolefin (100% homopolypropylene, melt index 4g / 10min, 230°C / 2.16kg), 18 parts by weight of filler (titanium dioxide), and 2 parts by weight of anti-aging agent (90% antioxidant 1010, 10% light stabilizer UV622).

[0100] The composite surface layer is 80 parts by weight of polyolefin (85% block polypropylene, melt index 5g / 10min, 230℃ / 2.16kg; 15% low-density polyethylene, melt index 4g / 10min, 190℃ / 2.16kg), 23 parts by weight of ethylene-propylene copolymer (ethylene content 6%), 1.5 parts by weight of filler (silicon dioxide), and 0.5 parts by weight of anti-aging agent (antioxidant 1010).

[0101] After each layer is fully mixed in a mixer, it is loaded into different screw extruders respectively, and extruded and cast into a composite film through a multi-channel T-die head according to the extrusion amount of printed surface layer: middle layer: composite surface layer = 1:6:1. The film is corona treated on both sides to obtain a polypropylene film with a thickness of 120 μm.

[0102] Example 2

[0103] The raw materials for preparing the polypropylene film are mixed by three T-die extruders using a casting method and then subjected to multi-layer co-extrusion treatment to obtain a polypropylene film having a printed surface layer, an intermediate layer and a composite surface layer.

[0104] The printed surface layer is 46 parts by weight of random polypropylene (Vicat softening point temperature 110°C, melt index 6g / 10min, 230°C / 2.16kg), 7.9 parts by weight of grafted polypropylene (grafting rate 1.0%, Vicat softening point temperature 100°C), 25 parts by weight of polar ethylene copolymer (EMA, MA content 18wt%), 15 parts by weight of ethylene-propylene copolymer (ethylene content 12%), 6 parts by weight of filler (silicon dioxide), and 0.1 parts by weight of anti-aging agent (antioxidant 1010). The Vicat softening point temperature of the printed surface layer is 90°C.

[0105] The middle layer is 83 parts by weight of polyolefin (100% homopolypropylene, melt index 4g / 10min, 230°C / 2.16kg), 15 parts by weight of filler (titanium dioxide), and 2 parts by weight of anti-aging agent (85% antioxidant 1010, 15% ultraviolet absorber UV1577).

[0106] The composite surface layer is 65 parts by weight of polyolefin (90% homopolypropylene, melt index 8g / 10min, 230℃ / 2.16kg; 10% metallocene polyethylene, melt index 3.5g / 10min, 190℃ / 2.16kg), 30 parts by weight of ethylene-propylene copolymer (ethylene content 8%), 4.5 parts by weight of filler (titanium dioxide), and 0.5 parts by weight of anti-aging agent (antioxidant 1010).

[0107] After each layer is fully mixed in a mixer, it is loaded into different screw extruders respectively, and extruded and cast into a composite film through a multi-channel T-die head according to the extrusion amount of printed surface layer: middle layer: composite surface layer = 1:6:1. The film is corona treated on both sides to obtain a polypropylene film with a thickness of 120 μm.

[0108] Example 3

[0109] The raw materials for preparing the polypropylene film are mixed by three T-die extruders using a casting method and then subjected to multi-layer co-extrusion treatment to obtain a polypropylene film having a printed surface layer, an intermediate layer and a composite surface layer.

[0110] The printed surface layer is composed of 59 parts by weight of terpolymer (Vicat softening point temperature 100°C, melt index 7g / 10min, 230°C / 2.16kg), 8.5 parts by weight of grafted polypropylene (grafting rate 1.0%, Vicat softening point temperature 100°C), 18 parts by weight of polar ethylene copolymer (EMA, MA content 20wt%), 8 parts by weight of propylene-octene copolymer (octene content 9%), 6 parts by weight of filler (silicon dioxide), and 0.5 parts by weight of antioxidant (90% antioxidant 1010, 10% antioxidant 168). The Vicat softening point temperature of the printed surface layer is 95°C.

[0111] The middle layer is polyolefin (95% block polypropylene, melt index 4g / 10min, 230℃ / 2.16kg; 5% linear low density polyethylene, melt index 4g / 10min, 190℃ / 2.16kg) 74 weight parts, filler (titanium dioxide 60%, calcium carbonate 40%) 25 weight parts, and anti-aging agent (antioxidant 1010) 1 weight part; the composite surface layer is polyolefin (100% block polypropylene, melt index 5g / 10min, 230℃ / 2.16kg) 75 weight parts, propylene octene copolymer (octene content 9%) 20 weight parts, filler (titanium dioxide) 4.5 weight parts, and anti-aging agent (90% antioxidant 1010, 10% antioxidant 168) 0.5 weight part.

[0112] After each layer is fully mixed in a mixer, it is loaded into different screw extruders respectively, and extruded and cast into a composite film through a multi-channel T-die head according to the extrusion amount of printed surface layer: middle layer: composite surface layer = 1:6:1. The film is corona treated on both sides to obtain a polypropylene film with a thickness of 120 μm.

[0113] Example 4

[0114] The raw materials for preparing the polypropylene film are mixed by three T-die extruders using a casting method and then subjected to multi-layer co-extrusion treatment to obtain a polypropylene film having a printed surface layer, an intermediate layer and a composite surface layer.

[0115] The printed surface layer is 65 parts by weight of random polypropylene (Vicat softening point temperature 120°C, melt index 8g / 10min, 230°C / 2.16kg), 6 parts by weight of grafted polypropylene (grafting rate 1.5%, Vicat softening point temperature 95°C), 8 parts by weight of polar ethylene copolymer (EMA, MA content 28wt%), 12 parts by weight of ethylene-propylene copolymer (ethylene content 8%), 8 parts by weight of filler (titanium dioxide), and 1 part by weight of anti-aging agent (antioxidant 3114). The Vicat softening point temperature of the printed surface layer is 107°C.

[0116] The middle layer is 74.5 parts by weight of polyolefin (100% block polypropylene, melt index 3.5g / 10min, 230°C / 2.16kg), 25 parts by weight of filler (titanium dioxide), and 0.5 parts by weight of anti-aging agent (antioxidant 3114).

[0117] The composite surface layer is 65 parts by weight of polyolefin (100% random polypropylene, melt index 6g / 10min, 230℃ / 2.16kg), 26.5 parts by weight of ethylene-propylene copolymer (ethylene content 8%), 8 parts by weight of filler (titanium dioxide), and 0.5 parts by weight of anti-aging agent (antioxidant 3114).

[0118] After each layer is fully mixed in a mixer, it is loaded into different screw extruders respectively, and extruded and cast into a composite film through a multi-channel T-die head according to the extrusion amount of printed surface layer: middle layer: composite surface layer = 1:6:1. The film is corona treated on both sides to obtain a polypropylene film with a thickness of 120 μm.

[0119] Example 5

[0120] The raw materials for preparing the polypropylene film are mixed by three T-die extruders using a casting method and then subjected to multi-layer co-extrusion treatment to obtain a polypropylene film having a printed surface layer, an intermediate layer and a composite surface layer.

[0121] The printed surface layer is 59 parts by weight of terpolymer (Vicat softening point 115°C, melt index 7g / 10min, 230°C / 2.16kg), 4 parts by weight of grafted polypropylene (grafting rate 1.5%, Vicat softening point temperature 95°C), 22 parts by weight of polar ethylene copolymer (EMA, MA content 22wt%), 10.4 parts by weight of ethylene-octene copolymer (melt index 6g / 10min, 190°C / 2.16kg), 4 parts by weight of filler (silicon dioxide), and 0.6 parts by weight of anti-aging agent (95% antioxidant 1010, 5% light stabilizer UV622). The Vicat softening point temperature of the printed surface layer is 98°C.

[0122] The middle layer is 90 parts by weight of polyolefin (100% homopolymer polypropylene, melt index 4g / 10min, 230°C / 2.16kg), 9 parts by weight of filler (titanium dioxide), and 1 part by weight of anti-aging agent (95% antioxidant 1010, 5% light stabilizer UV622).

[0123] The composite surface layer is 89 parts by weight of polyolefin (100% block polypropylene, melt index 5g / 10min, 230℃ / 2.16kg), 10 parts by weight of ethylene-octene copolymer (melt index 6g / 10min, 190℃ / 2.16kg), and 1 part by weight of anti-aging agent (antioxidant 1010).

[0124] After each layer is fully mixed in a mixer, it is loaded into different screw extruders respectively, and extruded and cast into a composite film through a multi-channel T-die head according to the extrusion amount of printed surface layer: middle layer: composite surface layer = 1:6:1. The film is corona treated on both sides to obtain a polypropylene film with a thickness of 120 μm.

[0125] Comparative Example 1

[0126] The raw materials for preparing the polypropylene film are mixed by three T-die extruders using a casting method and then subjected to multi-layer co-extrusion treatment to obtain a polypropylene film having a printed surface layer, an intermediate layer and a composite surface layer.

[0127] The printed surface layer is composed of 59 parts by weight of homopolypropylene (Vicat softening point temperature 155°C, melt index 5g / 10min, 230°C / 2.16kg), 8.5 parts by weight of grafted polypropylene (grafting rate 1.0%, Vicat softening point temperature 100°C), 18 parts by weight of polar ethylene copolymer (EMA, MA content 18wt%), 8 parts by weight of ethylene-propylene copolymer (ethylene content 8%), 6 parts by weight of filler (silicon dioxide), and 0.5 parts by weight of anti-aging agent (antioxidant 1010). The Vicat softening point temperature of the printed surface layer is 130°C.

[0128] The middle layer is composed of 74 parts by weight of polyolefin (100% homopolymer polypropylene, melt index 3g / 10min, 230°C / 2.16kg), 25 parts by weight of filler (titanium dioxide) and 1 part by weight of anti-aging agent.

[0129] The composite surface layer is 75 parts by weight of polyolefin (90% homopolypropylene, melt index 5g / 10min, 230℃ / 2.16kg; 10% low-density polyethylene, melt index 4g / 10min, 190℃ / 2.16kg), 20 parts by weight of ethylene-propylene copolymer (ethylene content 8%), 4.5 parts by weight of filler (titanium dioxide), and 0.5 parts by weight of anti-aging agent (antioxidant 1010).

[0130] After each layer is fully mixed in a mixer, it is loaded into different screw extruders respectively, and extruded and cast into a composite film through a multi-channel T-die head according to the extrusion amount of printed surface layer: middle layer: composite surface layer = 1:6:1. The film is corona treated on both sides to obtain a polypropylene film with a thickness of 120 μm.

[0131] Comparative Example 2

[0132] The raw materials for preparing the polypropylene film are mixed by three T-die extruders using a casting method and then subjected to multi-layer co-extrusion treatment to obtain a polypropylene film having a printed surface layer, an intermediate layer and a composite surface layer.

[0133] The printed surface layer is composed of 75 parts by weight of random polypropylene (Vicat softening point temperature 110°C, melt index 6g / 10min, 230°C / 2.16kg), 18.5 parts by weight of ethylene-propylene copolymer (ethylene content 8%), 6 parts by weight of filler (silicon dioxide), and 0.5 parts by weight of anti-aging agent (antioxidant 1010). The Vicat softening point temperature of the printed surface layer is 100°C.

[0134] The middle layer is 83 parts by weight of polyolefin (100% homopolymer polypropylene, melt index 4g / 10min, 230°C / 2.16kg), 5 parts by weight of filler (titanium dioxide), and 2 parts by weight of anti-aging agent (antioxidant 1010).

[0135] The composite surface layer is 65 parts by weight of polyolefin (90% homopolypropylene, melt index 8g / 10min, 230℃ / 2.16kg; 10% metallocene polyethylene, melt index 3.5g / 10min, 190℃ / 2.16kg), 30 parts by weight of ethylene-propylene copolymer (ethylene content 8%), 4.5 parts by weight of filler (titanium dioxide), and 0.5 parts by weight of anti-aging agent (antioxidant 1010).

[0136] After each layer is fully mixed in a mixer, it is loaded into different screw extruders respectively, and extruded and cast into a composite film through a multi-channel T-die head according to the extrusion amount of printed surface layer: middle layer: composite surface layer = 1:6:1. The film is corona treated on both sides to obtain a polypropylene film with a thickness of 120 μm.

[0137] Comparative Example 3

[0138] The raw materials for preparing the polypropylene film are mixed by three T-die extruders using a casting method and then subjected to multi-layer co-extrusion treatment to obtain a polypropylene film having a printed surface layer, an intermediate layer and a composite surface layer.

[0139] The printed surface layer is composed of 59 parts by weight of metallocene polyethylene (Vicat softening point temperature 85°C, melt index 3g / 10min, 190°C / 2.16kg), 8.5 parts by weight of grafted polypropylene (grafting rate 1.0%, Vicat softening point temperature 100°C), 18 parts by weight of polar ethylene copolymer (EMA, MA content 20wt%), 8 parts by weight of ethylene-propylene copolymer (ethylene content 8%), 6 parts by weight of filler (silicon dioxide), and 0.5 parts by weight of anti-aging agent (antioxidant 1010). The Vicat softening point temperature of the printed surface layer is 81°C.

[0140] The middle layer is 74 parts by weight of polyolefin (95% block polypropylene, melt index 4g / 10min, 230℃ / 2.16kg; 5% linear low-density polyethylene, melt index 4g / 10min, 190℃ / 2.16kg), 25 parts by weight of filler (60% titanium dioxide, 40% calcium carbonate), and 1 part by weight of anti-aging agent (antioxidant 1010).

[0141] The composite surface layer is 75 parts by weight of polyolefin (100% block polypropylene, melt index 5g / 10min, 230℃ / 2.16kg), 20 parts by weight of ethylene-propylene copolymer (ethylene content 8%), 4.5 parts by weight of filler (titanium dioxide), and 0.5 parts by weight of anti-aging agent (antioxidant 1010).

[0142] After each layer is fully mixed in a mixer, it is loaded into different screw extruders respectively, and extruded and cast into a composite film through a multi-channel T-die head according to the extrusion amount of printed surface layer: middle layer: composite surface layer = 1:6:1. The film is corona treated on both sides to obtain a polypropylene film with a thickness of 120 μm.

[0143] Performance Test:

[0144] After the polypropylene film is prepared in the above embodiments and comparative examples, a printing machine is used to print ink on the printed surface of the polypropylene film. After printing, the adhesion of the printing ink on the surface of the polypropylene film is tested. A transparent mask and a polypropylene film containing printing ink are thermally bonded at 130°C to complete the preparation of a polypropylene decorative film. The interlayer peeling force between the transparent mask and the polypropylene film is tested.

[0145] 1. Test method:

[0146] 1. Printing ink adhesion test: Evaluate according to ASTM D3359;

[0147] 2. Test method for peeling force of laminated mask: peel off the laminated decorative film, and then test according to item 6.7 of GB / T 31034-2014, using a universal tensile testing machine of model ETM-104B.

[0148] 2. Test results:

[0149] The performance test results of various embodiments and comparative examples are shown in Table 1.

[0150] Table 1 Performance test results of various embodiments and comparative examples

[0151]

[0152]

[0153] As shown in Table 1, the samples in Examples 1-5 have printing ink adhesion that meets the 5B requirement, the peeling force of the mask is greater than 5N / cm, and the interlayer fastness is not stratified. It shows that the polypropylene film of the present invention has excellent ink adhesion, especially can maintain good ink adhesion after high temperature bonding transparent mask. In Comparative Example 1, due to the high Vicat softening point temperature of polyethylene in the printed surface layer, and the Vicat softening point temperature of the printed surface layer is also too high, the ink falls off from the polypropylene film. The printed surface layer of Comparative Example 2 can meet the softening point requirements, but because the polar ethylene copolymer is not used in the components of the printed surface layer, its ink adhesion cannot meet the requirements of 5B, and the problem of ink falling off from the polypropylene film occurs when the peeling test is performed after thermal bonding. In Comparative Example 3, due to the low Vicat softening point temperature of polyethylene in the printed surface layer, it is the main resin of the printed surface layer. Although the ink adhesion can meet the requirements of 5B, its interlayer fastness is insufficient. When the peeling test is performed, the printed surface layer and the intermediate layer are stratified, indicating that the product stability is insufficient.

[0154] This indicates that the polypropylene film of the present invention has excellent ink adhesion, and can especially maintain good ink adhesion after being attached to a transparent mask at high temperature.

[0155] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0156] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A polypropylene film, characterized in that The polypropylene film comprises a printed surface layer, and the printed surface layer comprises the following raw materials in parts by weight: Polypropylene 46-65 parts; 4-10 parts of grafted polypropylene; 8-25 parts of polar ethylene copolymer; The Vicat softening point temperature of the polypropylene is 100-125°C; the Vicat softening point temperature of the printed surface layer is 90-110°C.

2. The polypropylene film according to claim 1, characterized in that The polypropylene includes at least one of terpolymer polypropylene and random copolymer polypropylene.

3. The polypropylene film according to claim 1, characterized in that The grafted polypropylene satisfies at least one of the following: (1) The grafting rate of the grafted polypropylene is 1 to 1.5%; (2) The Vicat softening point temperature of the grafted polypropylene is 95 to 110° C.; (3) The grafting monomer of the grafted polypropylene contains a carbonyl functional group.

4. The polypropylene film according to claim 1, characterized in that The polar ethylene copolymer satisfies at least one of the following: (A) the polar ethylene copolymer comprises a carbonyl functional group; (B) The polar ethylene copolymer is formed by polymerization of polar monomers and ethylene, and the content of the polar monomers in the reactants of the polymerization reaction is 18-28%.

5. The polypropylene film according to claim 1, characterized in that The printed surface layer also includes the following raw materials in parts by weight: 8-15 parts of alpha olefin copolymer; 2 to 8 parts of filler; Anti-aging agent 0.05 to 1 part.

6. The polypropylene film according to claim 5, characterized in that The printed surface layer satisfies at least one of the following: (a) the α-olefin copolymer comprises at least one of an ethylene-α-olefin copolymer and a propylene-α-olefin copolymer; (b) the Vicat softening point temperature of the α-olefin copolymer is 50 to 70° C.; (c) the filler comprises at least one of aluminum oxide, calcium carbonate, magnesium carbonate, aluminum sulfate, barium sulfate, aluminum silicate, magnesium silicate, titanium dioxide, and silicon dioxide; (d) The anti-aging agent includes at least one of an antioxidant, an ultraviolet absorber, a light stabilizer and a free radical quencher.

7. The polypropylene film according to claim 1, characterized in that The polypropylene film further comprises an intermediate layer and a composite surface layer, wherein the intermediate layer is located between the printed surface layer and the composite surface layer.

8. The polypropylene film according to claim 7, characterized in that The intermediate layer comprises the following raw materials in parts by weight: polyolefin, 74-90 parts by weight; filler, 9-25 parts by weight; anti-aging agent, 0.5-3 parts by weight.

9. The polypropylene film according to claim 7, characterized in that The composite surface layer comprises the following raw materials in parts by weight: polyolefin, 65-89 parts by weight; alpha olefin copolymer, 10-30 parts by weight; filler, 0-8 parts by weight; anti-aging agent, 0.2-1.5 parts by weight.

10. A polypropylene decorative film, characterized in that: The polypropylene film comprises the polypropylene film according to any one of claims 1 to 9.

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