BOPP (Biaxially-oriented Polypropylene) matt film with optimized cutting performance based on paper-plastic lamination and preparation method of BOPP matt film

Abstract

The invention relates to the field of films, in particular to a BOPP matt film with optimized cutting performance based on paper-plastic lamination and a preparation method of the BOPP matt film. The BOPP matt film comprises a matt layer, a core layer and a lower surface layer; the matt layer is prepared from polypropylene random copolymer, 40 to 55 weight percent of high-density polyethylene and 5 to 10 weight percent of polymethyl methacrylate-poly (butyl acrylate)-polymethyl methacrylate triblock copolymer; the core layer is prepared from homo-polypropylene, 10 to 15 weight percent of styrene-maleic anhydride copolymer and 3 to 8 weight percent of maleic anhydride grafted polypropylene; and the lower surface layer comprises homo-polypropylene. The components of the core layer and the matt layer are optimized, the brittleness of the core layer and the matt layer is improved, and the fracture resistance is reduced, so that after a laminated product obtained by laminating the BOPP matt film and paper is cut and broken, the length of a tail film is shortened, even the tail film is not generated, the application requirements of downstream customers are met, and high-speed automatic production can be realized.

Description

Technical Field

[0001] The present invention relates to the field of thin films, and particularly to a BOPP matte film with optimized cutting performance based on paper-plastic lamination and a preparation method thereof. Background Art

[0002] The biaxially oriented polypropylene matte film (BOPP matte film) can be a BOPP film with one matte side and one shiny side or both sides matte. Its matte effect is mainly achieved by scattering light; the matte effect can enhance the grade of printed outer packaging, giving a soft, fashionable and elegant high-class feeling, and can relieve eye fatigue. Therefore, the BOPP matte film is increasingly widely used in the packaging field, especially suitable for deep processing industries and fields such as coating and lamination.

[0003] Currently, the BOPP matte film used in the packaging field is mainly composed of a matte layer, a core layer and a shiny layer. Common processing applications include paper-plastic lamination (laminating with paper or paper boxes after coating or pre-coating an adhesive layer on the shiny side) or making labels. The commonly used thicknesses are 12μm and 15μm. In the application scenario of paper-plastic lamination, the shiny layer of the BOPP matte film will be continuously laminated with multiple sheets of paper after coating the glue, and then it is necessary to cut according to the size of the paper by a slitting knife to obtain several paper-plastic laminated products; during cutting, the slitting knife will first make a notch on one side of the paper-plastic laminated product, and then use the speed difference between the rear pressure roller and the front pressure roller to perform differential film breaking at the position corresponding to the notch.

[0004] The inventor found through a large number of practices that the existing BOPP matte film has the problem of poor lamination cutting performance. Poor lamination cutting performance will cause a small section of matte film (tail film) more than the paper to appear after film breaking. If the tail film is too long, the glue carried in the tail film will cause adjacent two layers of paper-plastic laminated products to stick together, resulting in the inability to normally carry out subsequent processing procedures such as UV and hot stamping that require automatic paper suction operation. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a BOPP matte film with optimized cutting performance based on paper-plastic lamination and a preparation method thereof. By optimizing the components of the core layer and the matte layer, the brittleness of the core layer and the matte layer is increased, so that the ability of the BOPP matte film to resist fracture is significantly reduced, and the BOPP matte film has good lamination cutting performance. When subjected to external stress, it will not show excessive deformation tolerance and fracture resistance. Furthermore, after the laminated product obtained by laminating the BOPP matte film with paper is cut and the film is broken, the length of the excess matte film (tail film) on the paper is reduced, and the problem that adjacent two layers of paper-plastic laminated products stick together due to the glue carried in the tail film is improved, or even no tail film is generated, meeting the application requirements of downstream customers and enabling high-speed automated production.

[0006] The technical solution of the present invention is realized in the following way: A BOPP matte film with optimized cutting performance based on paper-plastic lamination, comprising an extinction layer, a core layer and a lower surface layer arranged in sequence; the extinction layer comprises random copolymerized polypropylene, 40-55 wt% high-density polyethylene and 5-10 wt% polymethyl methacrylate-butyl acrylate-polymethyl methacrylate triblock copolymer; the core layer comprises homopolypropylene, 10-15 wt% styrene-maleic anhydride copolymer, 3-8 wt% maleic anhydride grafted polypropylene; the lower surface layer comprises homopolypropylene.

[0007] The inventor found through practice and analysis that: The main reason for the poor lamination cutting performance of the existing BOPP matte film is that the BOPP matte film has too high toughness and insufficient brittleness. The excessive deformation accommodation ability and fracture resistance (too strong ability to resist fracture) of the BOPP matte film, accompanied by a significant lack of brittleness, make it impossible for the BOPP matte film to break effectively when subjected to external stresses such as disc knife cutting and differential film breaking, and thus there will be a tail film with too long length.

[0008] First, in the three-layer structure of the extinction layer, core layer and lower surface layer of the existing BOPP matte film, the core layer has the highest proportion and is the main reflection layer of the mechanical properties of the BOPP matte film. Therefore, the selection of the core layer material directly affects the brittleness of the BOPP matte film; the currently common core layer substrate is homopolypropylene, and its glass transition temperature (Tg) is generally -10°C, showing a rubber phase (high elastic state) at room temperature. According to the brittle-ductile transition mechanism of polymer, when the temperature changes from low temperature to room temperature, the system changes from the glassy state at low temperature to the high elastic state, and the segmental movement ability of the molecular chain begins to be active. Therefore, by increasing the Tg of the core layer substrate, the brittle-ductile transition temperature of the core layer of the matte film can be shifted towards a higher temperature, so that the core layer substrate of the BOPP matte film is still in the glassy state at room temperature, thereby improving the room temperature brittleness of the core layer substrate and increasing the overall brittleness of the BOPP matte film substrate; specifically, introducing rigid or cross-linked groups into the core layer to form a three-dimensional network structure can enhance the intermolecular interaction force of polypropylene, limit the movement space and freedom of the homopolypropylene molecular chain, help to increase the Tg of the core layer, and is beneficial to increasing the overall brittleness of the core layer.

[0009] In addition, since the proportion of the matting layer in the BOPP matting film is second only to that of the core layer, the mechanical properties of the matting layer will also affect the brittleness of the BOPP matting film substrate; the main components of the matting layer are usually random copolymer polypropylene and high-density polyethylene (HDPE). Microscopically, the structure of the matting layer is similar to a "sea-island" structure, in which the random copolymer polypropylene acts as the soft phase and wraps the dispersed phase of high-density polyethylene; during the process of slitting the BOPP matting film with a slitting knife, the soft phase of the random copolymer polypropylene in the matting layer is the main phase that is cut and stretched. Similarly, according to the brittle-ductile transition mechanism of polymer, the overall brittleness of the matting layer can be improved by increasing the Tg of the soft phase, synergistically improving the brittleness of the core layer, and increasing the overall brittleness of the BOPP matting film, which is beneficial to reducing the length of the excess matting film (tail film) on the paper when the BOPP matting film undergoes slitting and differential film breaking during paper-plastic lamination applications, and even being able to not generate a tail film and form a neat cut.

[0010] Based on this, the present invention adds 10-15 wt% of styrene-maleic anhydride copolymer and 3-8 wt% of maleic anhydride grafted polypropylene to the core layer. Under the synergistic action of the two, the movement space and freedom of the homopolypropylene molecular chains are restricted, the Tg of the core layer of the BOPP matting film is increased, so that the core layer is still in a glassy state at room temperature, the brittleness of the core layer of the BOPP matting film is increased, which is beneficial to reducing the length of the excess matting film (tail film) on the paper when the BOPP matting film undergoes slitting during paper-plastic lamination applications, and even being able to not generate a tail film and form a neat cut.

[0011] Specifically, the present invention adds a styrene-maleic anhydride copolymer to the core layer. On the one hand, during the melt blending process of the homopolypropylene and the strong polar anhydride group of maleic anhydride in the styrene-maleic anhydride copolymer, some anhydride groups and homopolypropylene molecular chain segments are combined through a free radical grafting reaction to form physical cross-linking points with the homopolypropylene molecular chains, enhancing the intermolecular interaction force of the homopolypropylene and restricting the movement of the homopolypropylene chain segments to a certain extent. On the other hand, the Tg of the styrene-maleic anhydride copolymer is much higher than that of the homopolypropylene, and the overall Tg of the core layer can be effectively increased by blending. However, since the homopolypropylene is a non-polar polymer and has poor compatibility with the polar polymer of the styrene-maleic anhydride copolymer, the present invention also adds 3-8 wt% of maleic anhydride grafted polypropylene to the core layer to improve the compatibility between the homopolypropylene and the polar polymer of the styrene-maleic anhydride copolymer. By improving the compatibility of the interface between the two phases with maleic anhydride grafted polypropylene, the styrene-maleic anhydride copolymer can be evenly dispersed in the homopolypropylene matrix, and then the rigid benzene ring structure in the styrene-maleic anhydride copolymer can be fully utilized to further physically restrict the movement of the polypropylene molecular chain segments.

[0012] On this basis, if the content of styrene-maleic anhydride copolymer in the core layer is less than 10 wt%, the styrene-maleic anhydride copolymer cannot effectively enhance the intermolecular interaction of polypropylene and restrict the movement of polypropylene molecular segments, which is not conducive to increasing the Tg of the BOPP matte film substrate, and thus not conducive to improving the brittleness of the BOPP matte film substrate. If the content of styrene-maleic anhydride copolymer is higher than 15 wt%, the content of benzene ring rigid groups in the styrene-maleic anhydride copolymer is too high, which is likely to increase the risk of film breakage during the stretching process. If the content of maleic anhydride grafted polypropylene is less than 3 wt%, it is not conducive to improving the compatibility between the styrene-maleic anhydride copolymer and the homopolypropylene matrix, not conducive to the dispersion of the cyclic rigid structure in the styrene-maleic anhydride copolymer in the polypropylene matrix to restrict the movement of polypropylene molecular segments, not conducive to improving the overall brittleness of the BOPP matte film substrate, and not conducive to reducing the length of the tail film generated during the slitting of the BOPP matte film by a slitting knife in the paper-plastic lamination application. If the content of maleic anhydride grafted polypropylene is higher than 8 wt%, the polar groups in maleic anhydride aggregate in the non-polar homopolypropylene matrix to form rigid aggregates, and these aggregates will cause stress concentration during the biaxial stretching process, affecting the smoothness of production.

[0013] The poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer added in the matte layer of the present invention has poly(methyl methacrylate) side chains at both ends of the triblock structure. On the one hand, the poly(methyl methacrylate) chain segment belongs to a rigid chain segment, which is conducive to restricting the movement of the random copolymer polypropylene molecular chain. The triblock structure has the structural characteristics of hard-soft-hard, which is more conducive to restricting the movement of the random copolymer polypropylene molecular chain, thereby improving the brittleness of the matte layer and synergistically improving the overall brittleness of the matte film with the core layer. On the other hand, the Tg of the poly(methyl methacrylate) chain segment is as high as 105 °C, which can effectively increase the Tg of the soft-phase random copolymer polypropylene. Since both end segments of the triblock structure are poly(methyl methacrylate), it is more conducive to increasing the Tg of the soft-phase random copolymer polypropylene, thereby improving the brittleness of the matte layer. On the other hand, the flexible poly(butyl acrylate) chain segment in the triblock copolymer can form a physical bond with the random copolymer polypropylene soft phase through molecular chain entanglement to form an anchoring effect, reduce the interfacial tension between the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer and the random copolymer polypropylene, and improve the compatibility. Moreover, as a flexible elastomer, the poly(butyl acrylate) chain segment can also alleviate the appearance quality problem of cracks in the matte layer during the biaxial stretching of the matte film caused by the addition of the rigid poly(methyl methacrylate) chain segment through the bridging action of the elastomer microdomains.

[0014] On this basis, if the content of the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer in the matte layer is less than 5 wt%, it is not conducive to improving the brittleness of the soft phase of the matte layer, nor is it conducive to synergistically improving the overall brittleness of the BOPP matte film substrate with the core layer; if the content of the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer is higher than 15 wt%, due to the excessive content of the rigid chain segments of poly(methyl methacrylate), the risk of film breakage increases during the stretching process, affecting the smoothness of production.

[0015] Furthermore, in the chain segments of the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer that composes the matte layer, the ester groups in the poly(methyl methacrylate) chain segments have a certain polarity and can interact with the maleic anhydride polar groups in the styrene-maleic anhydride copolymer and maleic anhydride grafted polypropylene in the core layer, enabling the molecular chains of the matte layer and the core layer to penetrate and interweave with each other, forming a continuous network structure. This further restricts the degree of freedom of movement of the molecular chains in the matte layer and the core layer, making the molecular chains require higher energy to move, which is conducive to increasing the glass transition temperature of the overall matte film and reducing interface defects and stress concentration points. In addition, the poly(methyl methacrylate) chain segments added to the matte layer and the poly(butyl acrylate) chain segments (PBA chain segments) will form a microphase separation structure due to their different chemical properties. The poly(methyl methacrylate) chain segments and the molecular chains of the styrene-maleic anhydride copolymer in the core layer form an interpenetrating crosslinked network structure at the interface. This structure not only enhances the interfacial bonding force between layers but also restricts the overall movement of the molecular chains through chain segment entanglement, thereby increasing the glass transition temperature (Tg) of the film. At the same time, the PBA chain segments play a plasticizing and buffering role with their flexible long-chain structure. By forming an elastic transition layer at the phase interface, they effectively absorb the stress during the processing. This synergistic mechanism ensures the necessary flexibility of the film, not only ensuring the smooth stretching and forming of the film during production but also optimizing the cutting performance after subsequent paper-plastic lamination, achieving a balance between rigidity and toughness.

[0016] For the BOPP matte film with optimized cutting performance based on paper-plastic lamination of the present invention, by optimizing the components of the core layer and the matte layer and increasing the brittleness of the core layer and the matte layer, the ability of the BOPP matte film to resist fracture is significantly reduced. When subjected to external stress, it will not exhibit excessive deformation tolerance and fracture toughness, thereby reducing the length of the excess matte film (tail film) on the paper after the BOPP matte film is laminated with the paper and cut. Even no tail film is generated and a neat cut is formed, that is, the BOPP matte film has good lamination cutting performance.

[0017] Further, the preparation method of the styrene-maleic anhydride copolymer comprises the following steps: adding styrene and maleic anhydride monomers into a toluene solvent, and carrying out a free radical copolymerization reaction under the action of an azobisisobutyronitrile initiator; the molar content of the styrene monomer in the styrene-maleic anhydride copolymer is 3-4 mol%. When the molar content of the styrene monomer in the styrene-maleic anhydride copolymer is 3-4 mol%, the obtained styrene-maleic anhydride copolymer has the best effect of increasing the Tg of the core layer homopolypropylene and improving the brittleness of the core layer of the BOPP matte film; if the molar content of the styrene monomer in the styrene-maleic anhydride copolymer is lower than 3 mol%, the compatibility between the styrene-maleic anhydride copolymer and the homopolypropylene is poor, resulting in the agglomeration of the styrene-maleic anhydride copolymer in the homopolypropylene matrix, increasing the risk of stress concentration during the stretching process and affecting the smoothness of production; if the molar content of the styrene monomer in the styrene-maleic anhydride copolymer is higher than 4 mol%, the polarity of the styrene-maleic anhydride copolymer decreases, which is not conducive to the formation of physical cross-linking points with the molecular chains of the homopolypropylene, resulting in the weakening of the intermolecular interaction force of the homopolypropylene, reducing the Tg of the core layer homopolypropylene matrix, being not conducive to improving the brittleness of the BOPP matte film, being not conducive to shortening the length of the tail film generated after cutting and film breaking of the composite product made of the BOPP matte film and paper, and being not conducive to forming a neat cut on the paper for the BOPP matte film.

[0018] Further, the preparation method of the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer comprises the following steps: using toluene and anisole as a mixed solvent, adding methyl methacrylate, pentamethyldiethylenetriamine, and stannous octoate into a reaction flask, and reacting under the action of a double-ended brominated poly(butyl acrylate) macroinitiator and a catalyst CuCl2; the content of the poly(methyl methacrylate) chain segment in the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer is 60-80 mol%, and the content of the poly(butyl acrylate) chain segment is 20-40 mol%. If the content of the poly(butyl acrylate) chain segment in the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer > 40 mol%, it is not conducive to improving the brittleness of the soft phase (random copolymerized polypropylene) of the matte layer and is not conducive to synergistically improving the overall brittleness of the BOPP matte film with the core layer; if the content of the poly(butyl acrylate) chain segment in the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer < 20 mol%, too little poly(butyl acrylate) chain segment increases the risk of appearance quality problems such as cracks in the matte layer during the biaxial stretching process.

[0019] Further, the grafting rate of maleic anhydride in the maleic anhydride grafted polypropylene is 3-5 wt%, and the melt index of the maleic anhydride grafted polypropylene is measured to be 15-20 g / 10 min under the conditions of 230 °C and 2.16 kg. Within the above-defined ranges of the grafting rate and melt index of maleic anhydride, it is beneficial to the compatibility between the homopolypropylene and the styrene-maleic anhydride copolymer and the smooth production of the film. Preferably, the polypropylene in the maleic anhydride grafted polypropylene is homopolypropylene.

[0020] Further, the melt index of the homopolypropylene is measured to be 3-8 g / 10 min under the conditions of 230 °C and 2.16 kg. Within the above-defined range of the melt index, the homopolypropylene is beneficial to the thickness uniformity and smooth production during the biaxial stretching process.

[0021] Further, the melt index of the high-density polyethylene is measured to be 9-20 g / 10 min under the conditions of 190 °C and 2.16 kg; the melt index of the random copolymer polypropylene is measured to be 6-10 g / 10 min under the conditions of 230 °C and 2.16 kg, and the random copolymer polypropylene is a random ethylene-propylene copolymer. The high-density polyethylene and the random copolymer polypropylene within the above-defined ranges of the melt index are beneficial to obtaining an extinction layer with uniform extinction effect during the biaxial stretching process.

[0022] Further, the core layer further comprises 1-3 wt% of an antistatic agent, and the antistatic agent is a quaternary ammonium salt-based methacrylate copolymer.

[0023] Further, the lower surface layer further comprises 0.1-0.5 wt% of an anti-blocking agent, and the anti-blocking agent is one or more of silica, talcum powder, and calcium carbonate, and the particle size of the anti-blocking agent is 3-6 μm. Adding an appropriate amount of anti-blocking agent to the lower surface layer is beneficial to increasing the smoothness of unwinding and rewinding of the matte film. If the content of the anti-blocking agent is less than 0.1 wt%, it cannot play an effective anti-blocking role. If the content of the anti-blocking agent is higher than 0.5 wt%, on the one hand, the anti-blocking agent is likely to fall off and contaminate the guide roller during the production process, and on the other hand, it will increase the haze and reduce the glossiness, affecting the appearance of the product.

[0024] The present invention also provides a preparation method of the BOPP matte film with optimized cutting performance based on paper-plastic lamination as described in any one of the above, comprising the following steps: Ingredient preparation and plasticization: Set the raw material usage ratio in the control system of the biaxial stretching film production line, and then the ingredient system will automatically convey each layer of dried raw materials to the extruder according to the input ratio. After melting and plasticizing in the extruder, the melt enters the die head through the flow channel and the distributor; Sheet casting: After being extruded from the die head, the melt immediately contacts the cooling roll to form a thick sheet; Longitudinal stretching: The thick sheet is heated to a set temperature by multiple groups of preheating rollers, then starts longitudinal stretching and is then shaped. Transverse stretching: After preheating the thick sheet that has undergone longitudinal stretching to a set temperature, transverse stretching begins. After transverse stretching, shaping and cooling treatments are carried out. Traction and winding: The multi-layer structured film output from the transverse stretching unit enters the traction unit. After thickness measurement and corona treatment, it enters the winding unit to obtain the master roll. Slitting: The master roll that has undergone aging treatment is slit to obtain film rolls with specified widths and lengths.

[0025] Furthermore, the melting and extrusion temperature of the matte layer: 200 - 260 °C; the melting and extrusion temperature of the core layer and the lower surface layer: 230 - 260 °C; in the process of the melt contacting the cooling roll, the temperature of the chilled water and the cooling roll: 15 - 50 °C; the temperature in the longitudinal stretching zone: 90 - 130 °C; the temperature in the transverse stretching zone: 155 - 165 °C; the longitudinal stretching ratio is 4.5 - 5.5 times; the transverse stretching ratio: 8 - 10 times; the corona power factor of the matte layer: 20 - 25 W·min / m.

[0026] For better understanding and implementation, the present invention will be described in detail below. Specific embodiments

[0027] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the embodiments of the present application.

[0028] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0029] The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims. In the description of the present application, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects, and do not have to be used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0030] In addition, in the description of the present application, unless otherwise specified, "a plurality of" means two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0031] It should be understood that the embodiments of the present application are not limited to the exact structures described above, and various modifications and changes can be made without departing from its scope. The scope of the embodiments of the present application is only limited by the appended claims.

[0032] As an embodiment of the present invention, this embodiment provides a BOPP matte film with optimized cutting performance based on paper-plastic lamination, including an extinction layer, a core layer, and a lower surface layer arranged in sequence; the extinction layer includes random copolymerized polypropylene, 40-55 wt% high-density polyethylene, and 5-10 wt% polymethyl methacrylate-butyl acrylate-polymethyl methacrylate triblock copolymer; the core layer includes homopolypropylene, 10-15 wt% styrene-maleic anhydride copolymer, 3-8 wt% maleic anhydride grafted polypropylene; the lower surface layer includes homopolypropylene.

[0033] Further, the preparation method of the styrene-maleic anhydride copolymer includes the following steps: adding styrene and maleic anhydride monomers to a toluene solvent, and performing a free radical copolymerization reaction under the action of an azobisisobutyronitrile initiator; the molar content of styrene monomers in the styrene-maleic anhydride copolymer is 3-4 mol%.

[0034] Further, the preparation method of the polymethyl methacrylate-butyl acrylate-polymethyl methacrylate triblock copolymer includes the following steps: using toluene and anisole as a mixed solvent, adding methyl methacrylate, pentamethyldiethylenetriamine, and stannous octoate to a reaction flask, and reacting under the action of a double-ended brominated polybutyl acrylate macromolecular initiator and a catalyst CuCl2; the content of the polymethyl methacrylate chain segment in the polymethyl methacrylate-butyl acrylate-polymethyl methacrylate triblock copolymer is 60-80 mol%, and the content of the polybutyl acrylate chain segment is 20-40 mol%. The double-ended brominated polybutyl acrylate macromolecular initiator of the present invention is obtained by reacting butyl acrylate, bis(2-ethylhexyl) 2-bromoisobutyrate, copper bromide, pentamethyldiethylenetriamine, and stannous octoate reductant using toluene and anisole as a mixed solvent; the bis(2-ethylhexyl) 2-bromoisobutyrate of the present invention is obtained by reacting ethylene glycol, triethylamine, and α-bromoisobutyryl bromide using tetrahydrofuran as a solvent.

[0035] Further, the grafting rate of maleic anhydride in the maleic anhydride grafted polypropylene is 3-5 wt%, and the melt index of the maleic anhydride grafted polypropylene is measured to be 15-20 g / 10 min under the conditions of 230 °C and 2.16 kg.

[0036] Further, the melt index of the homopolypropylene is measured to be 3-8 g / 10 min under the conditions of 230 °C and 2.16 kg.

[0037] Further, the melt index of the high-density polyethylene is measured to be 9-20 g / 10 min under the conditions of 190 °C and 2.16 kg; the melt index of the random copolymer polypropylene is measured to be 6-10 g / 10 min under the conditions of 230 °C and 2.16 kg, and the random copolymer polypropylene is a random ethylene-propylene copolymer.

[0038] Further, the core layer further comprises 1-3 wt% of an antistatic agent, and the antistatic agent is a quaternary ammonium salt-based methacrylate copolymer.

[0039] Further, the lower surface layer further comprises 0.1-0.5 wt% of an anti-blocking agent, and the anti-blocking agent is one or more of silica, talcum powder, and calcium carbonate, and the particle size of the anti-blocking agent is 3-6 μm. In order to balance the surface layer thickness and the peeling problem, it is preferably 4-5 μm.

[0040] Further, the thickness of the matte layer is 1.8-2.2 μm, the thickness of the lower surface layer is 0.8-1.2 μm, and the total thickness of the biaxially oriented polypropylene matte film is 12-15 μm.

[0041] The present invention also provides a preparation method of the BOPP matte film for optimizing the cutting performance based on paper-plastic lamination as described in any one of the above, comprising the following steps: Formulation and plasticization: Set the raw material usage ratio in the control system of the biaxial stretching film production line, and then the batching system will automatically convey the dried raw materials of each layer to the extruder according to the input ratio. After melting and plasticizing in the extruder, the melt enters the die head through the runner and the distributor; Sheet casting: After being extruded from the die head, the melt immediately contacts the cooling roll to form a thick sheet; Longitudinal stretching: The thick sheet is heated to the set temperature by multiple groups of preheating rolls, and then longitudinal stretching is carried out, followed by shaping; Transverse stretching: After preheating the thick sheet that has been longitudinally stretched to the set temperature, transverse stretching is started, and after transverse stretching, shaping and cooling treatments are carried out; Traction and winding: The multi-layer structure film output from the transverse stretching unit enters the traction unit, and after thickness measurement and corona treatment, it enters the winding unit to obtain a master roll; Slitting: The aged master roll is slit to obtain film rolls with specified width and length.

[0042] Furthermore, the melt extrusion temperature of the matte layer: 200 - 260°C; the melt extrusion temperature of the core layer and the lower surface layer: 230 - 260°C; in the process of the melt contacting the cooling roll, the temperature of the chilled water and the chilled roll: 15 - 50°C; the temperature of the longitudinal stretching zone: 90 - 130°C; the temperature of the transverse stretching zone: 155 - 165°C; the longitudinal stretching ratio is 4.5 - 5.5 times; the transverse stretching ratio: 8 - 10 times; the corona power factor of the matte layer: 20 - 25 W·min / m.

[0043] The physical property indexes and their test methods of the embodiments or comparative examples of the present invention are specifically as follows: The melt index (melt mass flow rate MFR) is measured according to GB / T3682 - 2018.

[0044] Laminating and cutting performance: After the matte film is laminated with paper after applying glue, the length of the excess matte film on the paper after film breakage is visually judged (good effect: the length of the excess matte film on the paper is 0 - 1 mm; poor effect: the length of the excess matte film on the paper is > 1 mm).

[0045] Tensile strength: Tested according to GB / T1040.3 - 2006.

[0046] The antistatic agent in the embodiments and comparative examples of the present invention is a quaternary ammonium salt-based methacrylate copolymer.

[0047] The anti-blocking agent in the embodiments and comparative examples of the present invention is silica with a particle size of 4.5 μm.

[0048] It should be noted that the proportions described in the embodiments or comparative examples of the present invention are all weight percentages, and the component and content of each layer in the embodiments and comparative examples of the present invention are shown in Table 1 below.

[0049] Table 1

[0050] Example 1 This example provides a BOPP matte film with optimized cutting performance based on paper-plastic lamination, including a matte layer, a core layer, and a lower surface layer arranged in sequence. The preparation method of the resin of each layer of the BOPP matte film with optimized cutting performance based on paper-plastic lamination in this example includes the following steps: Preparation of the matting layer resin: Take 40 wt% of high-density polyethylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 15 g / 10 min), 50 wt% of random copolymerized polypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 8 g / 10 min), and 10 wt% of poly(methyl methacrylate-butyl acrylate-methyl methacrylate) triblock copolymer (the molar contents of the three segments in the poly(methyl methacrylate-butyl acrylate-methyl methacrylate) triblock copolymer are 40 mol%, 20 mol%, and 40 mol% in sequence), and mix them evenly to obtain the matting layer resin.

[0051] Preparation of the core layer resin: Take 86 wt% of homopolypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min), 10 wt% of styrene-maleic anhydride copolymer (the molar content of styrene monomer in the styrene-maleic anhydride copolymer is 3 mol%), 3 wt% of maleic anhydride grafted polypropylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 15 g / 10 min, and the grafting rate of maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 3 wt%), and 1 wt% of antistatic agent (quaternary ammonium salt-based methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0052] Preparation of the lower surface layer resin: Take 99.7 wt% of homopolypropylene (the isotacticity is 96%, and the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min) and 0.3 wt% of antiblocking agent (silica, particle size is 4.5 μm), and mix them evenly to obtain the lower surface layer resin.

[0053] The preparation method of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this embodiment includes the following steps: Ingredient preparation and plasticization: Set the raw material usage ratio in the control system of the biaxially oriented film production line. Then, the ingredient system will automatically convey the dried raw materials of each layer to the corresponding extruders according to the input ratio. After melting and plasticizing in the extruders, the melts of each layer enter the die head through the flow channels and distributors. Sheet casting: After being extruded from the die head, the melt immediately contacts the cooling roll to form a thick sheet. Longitudinal stretching: The thick sheet is heated to the set temperature by multiple groups of preheating rolls, and then longitudinal stretching is carried out, followed by shaping. Transverse stretching: After preheating the thick sheet that has undergone longitudinal stretching to the set temperature, transverse stretching is started. After transverse stretching, shaping and cooling treatments are carried out. Traction and winding: The multi-layer structure film output from the transverse stretching unit enters the traction unit. After thickness measurement and corona treatment, it enters the winding unit to obtain the master roll. Slitting: The aged master roll is slit to obtain a roll of BOPP matte film with optimized cutting performance based on paper-plastic lamination, having a specified width and length.

[0054] The melting extrusion temperature of the matte layer is 235°C; the melting extrusion temperature of the core layer is 250°C; the melting extrusion temperature of the lower surface layer is 250°C; the temperature of the chilled water and the chilled roll when the melt contacts the chilled roll is 40°C; the temperature for longitudinal stretching is 125°C; the temperature for transverse stretching is 160°C; the longitudinal stretching ratio is 5.3 times; the transverse stretching ratio is 8.5 times; the corona power factor of the matte layer is 23.5 W·min / m.

[0055] The total thickness of the matte film is 12 µm, where the thickness of the matte layer is 1.8 µm and the thickness of the lower surface layer is 1 µm.

[0056] Example 2 This example provides a BOPP matte film with optimized cutting performance based on paper-plastic lamination, including a matte layer, a core layer, and a lower surface layer arranged in sequence. The preparation method of the resins for each layer of the BOPP matte film with optimized cutting performance based on paper-plastic lamination in this example includes the following steps: Preparation of matte layer resin: Take 50 wt% high-density polyethylene (with a melt index of 15 g / 10 min measured under the conditions of 190°C and 2.16 kg), 42 wt% random copolymerized polypropylene (with a melt index of 8 g / 10 min measured under the conditions of 230°C and 2.16 kg), and 8 wt% poly(methyl methacrylate-butyl acrylate-methyl methacrylate) triblock copolymer (the molar contents of the three segments in the poly(methyl methacrylate-butyl acrylate-methyl methacrylate) triblock copolymer are 35 mol%, 30 mol%, and 35 mol% in sequence), and mix them evenly to obtain the matte layer resin. Preparation of core layer resin: Take 82 wt% homopolypropylene (with a melt index of 3 g / 10 min measured under the conditions of 230°C and 2.16 kg), 12 wt% styrene-maleic anhydride copolymer (the molar content of styrene monomer in the styrene-maleic anhydride copolymer is 3 mol%), 5 wt% maleic anhydride grafted polypropylene (with a melt index of 17 g / 10 min measured under the conditions of 190°C and 2.16 kg, and the grafting rate of maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 4 wt%), and 1 wt% antistatic agent (quaternary ammonium base methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0057] Preparation of lower surface layer resin: Take 99.7 wt% homopolypropylene (isotacticity is 96%, with a melt index of 3 g / 10 min measured under the conditions of 230°C and 2.16 kg) and 0.3 wt% anti-blocking agent (silica, particle size is 4.5 µm), and mix them evenly to obtain the lower surface layer resin.

[0058] The preparation method of the BOPP matte film with optimized cutting performance based on paper-plastic lamination in this example is the same as that in Example 1, so it will not be elaborated here.

[0059] The total thickness of the matte film is 12 µm, among which the thickness of the matte layer is 1.8 µm and the thickness of the lower surface layer is 1 µm.

[0060] Example 3 This example provides a BOPP matte film with optimized cutting performance based on paper-plastic lamination, including a matte layer, a core layer, and a lower surface layer arranged in sequence. The preparation method of the resins for each layer of the BOPP matte film with optimized cutting performance based on paper-plastic lamination in this example includes the following steps: Preparation of the matte layer resin: Take 55 wt% high-density polyethylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 15 g / 10 min), 40 wt% random copolymer polypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 8 g / 10 min), and 5 wt% polymethyl methacrylate - polybutyl acrylate - polymethyl methacrylate triblock copolymer (the molar contents of the three segments in the polymethyl methacrylate - polybutyl acrylate - polymethyl methacrylate triblock copolymer are 30 mol%, 40 mol%, and 30 mol% in sequence), and mix them evenly to obtain the matte layer resin. Preparation of the core layer resin: Take 76 wt% homopolypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min), 15 wt% styrene - maleic anhydride copolymer (the molar content of the styrene monomer in the styrene - maleic anhydride copolymer is 4 mol%), 8 wt% maleic anhydride grafted polypropylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 20 g / 10 min, and the grafting rate of the maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 5 wt%), and 1 wt% antistatic agent (quaternary ammonium salt-based methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0061] Preparation of the lower surface layer resin: Take 99.7 wt% homopolypropylene (the isotacticity is 96%, and the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min) and 0.3 wt% anti-blocking agent (silica, with a particle size of 4.5 µm), and mix them evenly to obtain the lower surface layer resin.

[0062] The preparation method of the BOPP matte film with optimized cutting performance based on paper-plastic lamination in this example is the same as that in Example 1, so it will not be elaborated here.

[0063] The total thickness of the matte film is 12 µm, among which the thickness of the matte layer is 1.8 µm and the thickness of the lower surface layer is 1 µm.

[0064] Comparative Example 1 This comparative example provides a BOPP matte film with optimized cutting performance based on paper-plastic lamination, which includes a matte layer, a core layer, and a lower surface layer arranged in sequence. The preparation method of the resins for each layer of the BOPP matte film with optimized cutting performance based on paper-plastic lamination in this comparative example includes the following steps: Preparation of matte layer resin: Take 55 wt% high-density polyethylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 15 g / 10 min), and 45 wt% random copolymer polypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 8 g / 10 min), and mix them evenly to obtain the matte layer resin.

[0065] Preparation of core layer resin: Take 82 wt% homopolypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min), 12 wt% styrene-maleic anhydride copolymer (the molar content of styrene monomer in the styrene-maleic anhydride copolymer is 3 mol%), 5 wt% maleic anhydride grafted polypropylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 20 g / 10 min, and the grafting rate of maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 5 wt%), and 1 wt% antistatic agent (quaternary ammonium base methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0066] Preparation of lower surface layer resin: Take 99.7 wt% homopolypropylene (isotacticity is 96%, and the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min) and 0.3 wt% antiblocking agent (silica, particle size is 4.5 μm), and mix them evenly to obtain the lower surface layer resin.

[0067] The preparation method of the BOPP matte film with optimized cutting performance based on paper-plastic lamination in this comparative example is the same as that in Example 1, so it will not be elaborated here.

[0068] The total thickness of the matte film is 12 µm, among which the thickness of the matte layer is 1.8 µm, and the thickness of the lower surface layer is 1 µm.

[0069] Comparative Example 2 This comparative example provides a BOPP matte film with optimized cutting performance based on paper-plastic lamination, which includes a matte layer, a core layer, and a lower surface layer arranged in sequence. The preparation method of the resins for each layer of the BOPP matte film with optimized cutting performance based on paper-plastic lamination in this comparative example includes the following steps: Preparation of the matting layer resin: Take 55 wt% of high-density polyethylene (with a melt index of 15 g / 10 min measured under the conditions of 190 °C and 2.16 kg), 43 wt% of random copolymerized polypropylene (with a melt index of 8 g / 10 min measured under the conditions of 230 °C and 2.16 kg), and 2 wt% of poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer (the molar contents of the three segments in the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer are 30 mol%, 40 mol%, and 30 mol% in sequence), and mix them evenly to obtain the matting layer resin.

[0070] Preparation of the core layer resin: Take 82 wt% of homopolypropylene (with a melt index of 3 g / 10 min measured under the conditions of 230 °C and 2.16 kg), 12 wt% of styrene-maleic anhydride copolymer (the molar content of styrene monomer in the styrene-maleic anhydride copolymer is 3 mol%), 5 wt% of maleic anhydride grafted polypropylene (with a melt index of 20 g / 10 min measured under the conditions of 190 °C and 2.16 kg, and the grafting rate of maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 5 wt%), and 1 wt% of antistatic agent (quaternary ammonium salt-based methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0071] Preparation of the lower surface layer resin: Take 99.7 wt% of homopolypropylene (isotacticity is 96%, with a melt index of 3 g / 10 min measured under the conditions of 230 °C and 2.16 kg) and 0.3 wt% of antiblocking agent (silica, particle size is 4.5 μm), and mix them evenly to obtain the lower surface layer resin.

[0072] The preparation method of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example is the same as that in Example 1, so it will not be elaborated here.

[0073] The total thickness of the matting film is 12 µm, among which the thickness of the matting layer is 1.8 µm and the thickness of the lower surface layer is 1 µm.

[0074] Comparative Example 3 This comparative example provides a BOPP matting film with optimized cutting performance based on paper-plastic lamination, including a matting layer, a core layer, and a lower surface layer arranged in sequence. The preparation methods of the resins for each layer of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example include the following steps: Preparation of the matting layer resin: Take 45 wt% of high-density polyethylene (with a melt index of 15 g / 10 min measured under the conditions of 190 °C and 2.16 kg), 40 wt% of random copolymer polypropylene (with a melt index of 8 g / 10 min measured under the conditions of 230 °C and 2.16 kg), and 15 wt% of poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer (the molar contents of the three segments in the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer are 30 mol%, 40 mol%, and 30 mol% in sequence), and mix them evenly to obtain the matting layer resin.

[0075] Preparation of the core layer resin: Take 82 wt% of homopolypropylene (with a melt index of 3 g / 10 min measured under the conditions of 230 °C and 2.16 kg), 12 wt% of styrene-maleic anhydride copolymer (the molar content of styrene monomer in the styrene-maleic anhydride copolymer is 3 mol%), 5 wt% of maleic anhydride grafted polypropylene (with a melt index of 20 g / 10 min measured under the conditions of 190 °C and 2.16 kg, and the grafting rate of maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 5 wt%), and 1 wt% of antistatic agent (quaternary ammonium salt-based methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0076] Preparation of the lower surface layer resin: Take 99.7 wt% of homopolypropylene (isotacticity is 96%, with a melt index of 3 g / 10 min measured under the conditions of 230 °C and 2.16 kg) and 0.3 wt% of antiblocking agent (silica, particle size is 4.5 μm), and mix them evenly to obtain the lower surface layer resin.

[0077] The preparation method of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example is the same as that in Example 1, so it will not be elaborated here.

[0078] The total thickness of the matting film is 12 µm, among which the thickness of the matting layer is 1.8 µm, and the thickness of the lower surface layer is 1 µm.

[0079] Comparative Example 4 This comparative example provides a BOPP matting film with optimized cutting performance based on paper-plastic lamination, including a matting layer, a core layer, and a lower surface layer arranged in sequence. The preparation method of each layer resin of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example includes the following steps: Preparation of the matting layer resin: Take 50 wt% of high-density polyethylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 15 g / 10 min), 42 wt% of random copolymerized polypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 8 g / 10 min), and 8 wt% of poly(methyl methacrylate-butyl acrylate-methyl methacrylate) triblock copolymer (the molar contents of the three segments in the poly(methyl methacrylate-butyl acrylate-methyl methacrylate) triblock copolymer are 20 mol%, 60 mol%, and 20 mol% in sequence), and mix them evenly to obtain the matting layer resin.

[0080] Preparation of the core layer resin: Take 82 wt% of homopolypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min), 12 wt% of styrene-maleic anhydride copolymer (the molar content of styrene monomer in the styrene-maleic anhydride copolymer is 3 mol%), 5 wt% of maleic anhydride grafted polypropylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 20 g / 10 min, and the grafting rate of maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 5 wt%), and 1 wt% of antistatic agent (quaternary ammonium salt-based methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0081] Preparation of the lower surface layer resin: Take 99.7 wt% of homopolypropylene (isotacticity is 96%, and the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min) and 0.3 wt% of antiblocking agent (silica, particle size is 4.5 μm), and mix them evenly to obtain the lower surface layer resin.

[0082] The preparation method of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example is the same as that in Example 1, so it will not be elaborated here.

[0083] The total thickness of the matting film is 12 µm, among which the thickness of the matting layer is 1.8 µm, and the thickness of the lower surface layer is 1 µm.

[0084] Comparative Example 5 This comparative example provides a BOPP matting film with optimized cutting performance based on paper-plastic lamination, including a matting layer, a core layer, and a lower surface layer arranged in sequence. The preparation method of each layer of resin of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example includes the following steps: Preparation of the matting layer resin: Take 50 wt% of high-density polyethylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 15 g / 10 min), 42 wt% of random copolymerized polypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 8 g / 10 min), and 8 wt% of poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer (the molar contents of the three segments in the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer are 45 mol%, 10 mol%, and 45 mol% in sequence), and mix them evenly to obtain the matting layer resin.

[0085] Preparation of the core layer resin: Take 82 wt% of homopolypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min), 12 wt% of styrene-maleic anhydride copolymer (the molar content of styrene monomer in the styrene-maleic anhydride copolymer is 3 mol%), 5 wt% of maleic anhydride grafted polypropylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 20 g / 10 min, and the grafting rate of maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 5 wt%), and 1 wt% of antistatic agent (quaternary ammonium base methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0086] Preparation of the lower surface layer resin: Take 99.7 wt% of homopolypropylene (the isotacticity is 96%, and the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min) and 0.3 wt% of antiblocking agent (silica, particle size is 4.5 μm), and mix them evenly to obtain the lower surface layer resin.

[0087] The preparation method of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example is the same as that in Example 1, so it will not be elaborated here.

[0088] The total thickness of the matting film is 12 µm, among which the thickness of the matting layer is 1.8 µm, and the thickness of the lower surface layer is 1 µm.

[0089] Comparative Example 6 This comparative example provides a BOPP matting film with optimized cutting performance based on paper-plastic lamination, including a matting layer, a core layer, and a lower surface layer arranged in sequence. The preparation method of each layer resin of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example includes the following steps: Preparation of the matting layer resin: Take 50 wt% of high-density polyethylene (with a melt index of 15 g / 10 min measured under the conditions of 190 °C and 2.16 kg), 42 wt% of random copolymerized polypropylene (with a melt index of 8 g / 10 min measured under the conditions of 230 °C and 2.16 kg), and 8 wt% of poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer (the molar contents of the three segments in the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer are 30 mol%, 40 mol%, and 30 mol% in sequence), and mix them evenly to obtain the matting layer resin.

[0090] Preparation of the core layer resin: Take 94 wt% of homopolypropylene (with a melt index of 3 g / 10 min measured under the conditions of 230 °C and 2.16 kg), 5 wt% of maleic anhydride grafted polypropylene (with a melt index of 20 g / 10 min measured under the conditions of 190 °C and 2.16 kg, and the grafting rate of maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 5 wt%), and 1 wt% of antistatic agent (quaternary ammonium base methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0091] Preparation of the lower surface layer resin: Take 99.7 wt% of homopolypropylene (isotacticity is 96%, with a melt index of 3 g / 10 min measured under the conditions of 230 °C and 2.16 kg) and 0.3 wt% of antiblocking agent (silica, particle size is 4.5 μm), and mix them evenly to obtain the lower surface layer resin.

[0092] The preparation method of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example is the same as that in Example 1, so it will not be elaborated here.

[0093] The total thickness of the matting film is 12 µm, among which the thickness of the matting layer is 1.8 µm, and the thickness of the lower surface layer is 1 µm.

[0094] Comparative Example 7 This comparative example provides a BOPP matting film with optimized cutting performance based on paper-plastic lamination, including a matting layer, a core layer, and a lower surface layer arranged in sequence. The preparation method of the resins for each layer of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example includes the following steps: Preparation of the matting layer resin: Take 50 wt% of high-density polyethylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 15 g / 10 min), 42 wt% of random copolymerized polypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 8 g / 10 min), and 8 wt% of poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer (the molar contents of the three segments in the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer are 30 mol%, 40 mol%, and 30 mol% in sequence), and mix them evenly to obtain the matting layer resin.

[0095] Preparation of the core layer resin: Take 89 wt% of homopolypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min), 5 wt% of styrene-maleic anhydride copolymer (the molar content of styrene monomer in the styrene-maleic anhydride copolymer is 3 mol%), 5 wt% of maleic anhydride grafted polypropylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 20 g / 10 min, and the grafting rate of maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 5 wt%), and 1 wt% of antistatic agent (quaternary ammonium base methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0096] Preparation of the lower surface layer resin: Take 99.7 wt% of homopolypropylene (isotacticity is 96%, and the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min) and 0.3 wt% of anti-blocking agent (silica, particle size is 4.5 μm), and mix them evenly to obtain the lower surface layer resin.

[0097] The preparation method of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example is the same as that in Example 1, so it will not be elaborated here.

[0098] The total thickness of the matting film is 12 µm, among which the thickness of the matting layer is 1.8 µm and the thickness of the lower surface layer is 1 µm.

[0099] Comparative Example 8 This comparative example provides a BOPP matting film with optimized cutting performance based on paper-plastic lamination, including a matting layer, a core layer, and a lower surface layer arranged in sequence. The preparation method of the resins of each layer of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example includes the following steps: Preparation of the matting layer resin: Take 50 wt% of high-density polyethylene (with a melt index of 15 g / 10 min measured under the conditions of 190 °C and 2.16 kg), 42 wt% of random copolymerized polypropylene (with a melt index of 8 g / 10 min measured under the conditions of 230 °C and 2.16 kg), and 8 wt% of poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer (the molar contents of the three segments in the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer are 30 mol%, 40 mol%, and 30 mol% in sequence), and mix them evenly to obtain the matting layer resin.

[0100] Preparation of the core layer resin: Take 74 wt% of homopolypropylene (with a melt index of 3 g / 10 min measured under the conditions of 230 °C and 2.16 kg), 20 wt% of styrene-maleic anhydride copolymer (the molar content of styrene monomer in the styrene-maleic anhydride copolymer is 3 mol%), 5 wt% of maleic anhydride grafted polypropylene (with a melt index of 20 g / 10 min measured under the conditions of 190 °C and 2.16 kg, and the grafting rate of maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 5 wt%), and 1 wt% of antistatic agent (quaternary ammonium base methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0101] Preparation of the lower surface layer resin: Take 99.7 wt% of homopolypropylene (isotacticity is 96%, with a melt index of 3 g / 10 min measured under the conditions of 230 °C and 2.16 kg) and 0.3 wt% of antiblocking agent (silica, particle size is 4.5 μm), and mix them evenly to obtain the lower surface layer resin.

[0102] The preparation method of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example is the same as that in Example 1, so it will not be elaborated here.

[0103] The total thickness of the matting film is 12 μm, among which the thickness of the matting layer is 1.8 μm and the thickness of the lower surface layer is 1 μm.

[0104] Comparative Example 9 This comparative example provides a BOPP matting film with optimized cutting performance based on paper-plastic lamination, including a matting layer, a core layer, and a lower surface layer arranged in sequence. The preparation method of the resins of each layer of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example includes the following steps: Preparation of the matting layer resin: Take 50 wt% high-density polyethylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 15 g / 10 min), 42 wt% random copolymerized polypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 8 g / 10 min), and 8 wt% poly(methyl methacrylate-butyl acrylate-methyl methacrylate) triblock copolymer (the molar contents of the three segments in the poly(methyl methacrylate-butyl acrylate-methyl methacrylate) triblock copolymer are 30 mol%, 40 mol%, and 30 mol% in sequence), and mix them evenly to obtain the matting layer resin.

[0105] Preparation of the core layer resin: Take 82 wt% homopolypropylene (the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min), 12 wt% styrene-maleic anhydride copolymer (the molar content of styrene monomer in the styrene-maleic anhydride copolymer is 6 mol%), 5 wt% maleic anhydride grafted polypropylene (the melt index measured under the conditions of 190 °C and 2.16 kg is 20 g / 10 min, and the grafting rate of maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 5 wt%), and 1 wt% antistatic agent (quaternary ammonium salt-based methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0106] Preparation of the lower surface layer resin: Take 99.7 wt% homopolypropylene (isotacticity is 96%, and the melt index measured under the conditions of 230 °C and 2.16 kg is 3 g / 10 min) and 0.3 wt% anti-blocking agent (silica, particle size is 4.5 μm), and mix them evenly to obtain the lower surface layer resin.

[0107] The preparation method of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example is the same as that in Example 1, so it will not be elaborated here.

[0108] The total thickness of the matting film is 12 µm, among which the thickness of the matting layer is 1.8 µm, and the thickness of the lower surface layer is 1 µm.

[0109] Comparative Example 10 This comparative example provides a BOPP matting film with optimized cutting performance based on paper-plastic lamination, including a matting layer, a core layer, and a lower surface layer arranged in sequence. The preparation methods of the resins for each layer of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example include the following steps: Preparation of the matting layer resin: Take 50 wt% of high-density polyethylene (with a melt index of 15 g / 10 min measured under the conditions of 190 °C and 2.16 kg), 42 wt% of random copolymerized polypropylene (with a melt index of 8 g / 10 min measured under the conditions of 230 °C and 2.16 kg), and 8 wt% of polymethyl methacrylate-butyl acrylate-polymethyl methacrylate triblock copolymer (the molar contents of the three segments in the polymethyl methacrylate-butyl acrylate-polymethyl methacrylate triblock copolymer are 30 mol%, 40 mol%, and 30 mol% in sequence), and mix them evenly to obtain the matting layer resin.

[0110] Preparation of the core layer resin: Take 82 wt% of homopolypropylene (with a melt index of 3 g / 10 min measured under the conditions of 230 °C and 2.16 kg), 12 wt% of styrene-maleic anhydride copolymer (the molar content of styrene monomer in the styrene-maleic anhydride copolymer is 1 mol%), 5 wt% of maleic anhydride grafted polypropylene (with a melt index of 20 g / 10 min measured under the conditions of 190 °C and 2.16 kg, and the grafting rate of maleic anhydride grafted polypropylene in the maleic anhydride grafted polypropylene is 5 wt%), and 1 wt% of antistatic agent (quaternary ammonium base methacrylate copolymer), and mix them evenly to obtain the core layer resin.

[0111] Preparation of the lower surface layer resin: Take 99.7 wt% of homopolypropylene (isotacticity is 96%, with a melt index of 3 g / 10 min measured under the conditions of 230 °C and 2.16 kg) and 0.3 wt% of antiblocking agent (silica, particle size is 4.5 μm), and mix them evenly to obtain the lower surface layer resin.

[0112] The preparation method of the BOPP matting film with optimized cutting performance based on paper-plastic lamination in this comparative example is the same as that in Example 1, so it will not be elaborated here.

[0113] The total thickness of the matting film is 12 µm, among which the thickness of the matting layer is 1.8 µm, and the thickness of the lower surface layer is 1 µm.

[0114] The performance test and lamination cutting performance test results of the BOPP matting films with optimized cutting performance based on paper-plastic lamination in Examples 1 to 3 and Comparative Examples 1 to 10 are shown in Table 2 below.

[0115] Table 2

[0116] From the above performance test data, it can be seen that in Examples 1-3 of the present invention, the lamination cutting performance is improved, and when the BOPP matting film is subjected to external stress, it does not exhibit excessive deformation tolerance and fracture resistance toughness. That is, its ability to resist fracture is significantly reduced, so that after the glue is applied and laminated with the paper, the length of the excess matting film on the paper after film breakage meets the application requirements of downstream customers and meets the high-speed automated production of the BOPP matting film.

[0117] For the BOPP matting film with improved lamination cutting performance in Comparative Example 1, the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer is not added to the matting layer, and the deformation tolerance and fracture resistance toughness are strong. Therefore, the tensile strength is low and the tail film is long. For the BOPP matting film with improved lamination cutting performance in Comparative Example 2, the content of the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer added to the matting layer is too low, which is not conducive to improving the brittleness of the soft phase of the matting layer and is not conducive to synergistically improving the overall brittleness of the BOPP matting film substrate with the core layer. Therefore, the tensile strength is low and the tail film is long. For the BOPP matting film with improved lamination cutting performance in Comparative Example 3, the content of the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer added to the matting layer is too high, and film breakage occurs during the stretching process, affecting the smoothness of production. For the BOPP matting film with improved lamination cutting performance in Comparative Example 4, the content ratio of the poly(butyl acrylate) chain segment in the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer added to the matting layer is too high, which is not conducive to improving the brittleness of the soft phase of the matting layer and is not conducive to synergistically improving the overall brittleness of the BOPP matting film substrate with the core layer, resulting in a decrease in tensile strength and an increase in the tail film length. For the BOPP matting film with improved lamination cutting performance in Comparative Example 5, the content ratio of the poly(butyl acrylate) chain segment in the poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) triblock copolymer added to the matting layer is too low, and during the biaxial stretching process of the BOPP matting film, appearance quality problems such as cracks appear in the matting layer. For the BOPP matting film with improved lamination cutting performance in Comparative Example 6, the styrene-maleic anhydride copolymer is not added to the core layer, and the movement space and freedom of the homopolypropylene molecular chains in the core layer are not restricted. The Tg of the BOPP matting film core layer is not increased, and the BOPP matting film substrate is still in a glassy state at room temperature. The overall brittleness of the BOPP matting film substrate is low. Therefore, the tensile strength is low and the tail film is long. For the BOPP matte film with improved lamination cutting performance in Comparative Example 7, the content of styrene-maleic anhydride copolymer added to the core layer is too low, and the effect of the styrene-maleic anhydride copolymer in enhancing the intermolecular interaction of polypropylene and restricting the movement of polypropylene molecular segments in the polypropylene matrix is insufficient, which is not conducive to increasing the Tg of the BOPP matte film substrate and has a poor effect on improving the brittleness of the BOPP matte film substrate. Therefore, the tensile strength is low and the tail film is long; For the BOPP matte film with improved lamination cutting performance in Comparative Example 8, the content of styrene-maleic anhydride copolymer added to the core layer is too high, and the content of cyclic rigid groups in the styrene-maleic anhydride copolymer is too much, resulting in film breakage during the stretching process; For the BOPP matte film with improved lamination cutting performance in Comparative Example 9, the molar content of styrene monomer in the styrene-maleic anhydride copolymer in the core layer is too high, resulting in a decrease in the polarity of the styrene-maleic anhydride copolymer, which is not conducive to forming physical cross-linking points with the homopolypropylene molecular chains and enhancing the intermolecular interaction of polypropylene. Moreover, it reduces the Tg of the styrene-maleic anhydride copolymer, which is not conducive to improving the overall brittleness of the BOPP matte film substrate and is not conducive to improving the performance of the BOPP matte film in forming neat incisions during die cutting in paper-plastic lamination applications. Therefore, the tensile strength is low and the tail film is long; For the BOPP matte film with improved lamination cutting performance in Comparative Example 10, the molar content of styrene monomer in the styrene-maleic anhydride copolymer in the core layer is too low, and the effect of improving the compatibility between the styrene-maleic anhydride copolymer and homopolypropylene is poor, resulting in agglomeration of the styrene-maleic anhydride copolymer in the homopolypropylene matrix. Coupled with the influence of the benzene ring rigid group, film breakage occurs during the stretching process, affecting the smoothness of production.

[0118] The above-described embodiments merely represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and the present invention also intends to include these changes and modifications.

Claims

1. A BOPP matte film with optimized cutting performance based on paper-plastic lamination, characterized in that, It includes an extinction layer, a core layer, and a lower surface layer arranged in sequence; the extinction layer includes random copolymerized polypropylene, 40-55 wt% high-density polyethylene, and 5-10 wt% polymethyl methacrylate-butyl acrylate-polymethyl methacrylate triblock copolymer; the core layer includes homopolypropylene, 10-15 wt% styrene-maleic anhydride copolymer, 3-8 wt% maleic anhydride grafted polypropylene; the lower surface layer includes homopolypropylene.

2. The BOPP matte film with optimized cutting performance based on paper-plastic lamination according to claim 1, characterized in that, The preparation method of the styrene-maleic anhydride copolymer includes the following steps: adding styrene and maleic anhydride monomers into a toluene solvent, and carrying out free radical copolymerization reaction under the action of an azodiisobutyronitrile initiator; the molar content of styrene monomer in the styrene-maleic anhydride copolymer is 3-4 mol%.

3. The BOPP matte film with optimized cutting performance based on paper-plastic lamination according to claim 1, wherein, The preparation method of the polymethyl methacrylate-butyl acrylate-polymethyl methacrylate triblock copolymer includes the following steps: using toluene and anisole as a mixed solvent, adding methyl methacrylate, pentamethyldiethylenetriamine, and stannous octoate into a reaction flask, and reacting under the action of a double-ended brominated polybutyl acrylate macroinitiator and a catalyst CuCl2; the content of the polymethyl methacrylate chain segment in the polymethyl methacrylate-butyl acrylate-polymethyl methacrylate triblock copolymer is 60-80 mol%, and the content of the polybutyl acrylate chain segment is 20-40 mol%.

4. The BOPP matte film with optimized cutting performance based on paper-plastic lamination according to claim 1, characterized in that, The grafting rate of maleic anhydride in the maleic anhydride grafted polypropylene is 3-5 wt%, and the melt index of the maleic anhydride grafted polypropylene is measured to be 15-20 g / 10 min under the conditions of 230 °C and 2.16 kg.

5. The BOPP matte film with optimized cutting performance based on paper-plastic lamination according to claim 1, characterized in that, The melt index of the homopolypropylene is measured to be 3-8 g / 10 min under the conditions of 230 °C and 2.16 kg.

6. The BOPP matte film with optimized cutting performance based on paper-plastic lamination according to claim 1, characterized in that, The melt index of the high-density polyethylene is measured to be 9-20 g / 10 min under the conditions of 190 °C and 2.16 kg; the melt index of the random copolymerized polypropylene is measured to be 6-10 g / 10 min under the conditions of 230 °C and 2.16 kg, and the random copolymerized polypropylene is a random ethylene-propylene copolymer.

7. The BOPP matte film with optimized cutting performance based on paper-plastic lamination according to claim 1, wherein The core layer further includes 1-3 wt% of an antistatic agent, and the antistatic agent is a quaternary ammonium salt-based methacrylate copolymer.

8. The BOPP matte film with optimized cutting performance based on paper-plastic lamination according to claim 1, characterized in that, The lower surface layer further includes 0.1-0.5 wt% of an anti-blocking agent, the anti-blocking agent is one or more of silica, talcum powder, and calcium carbonate, and the particle size of the anti-blocking agent is 3-6 μm.

9. A method for preparing a BOPP matte film with optimized cutting performance based on paper-plastic lamination according to any one of claims 1 to 8, characterized in that, It includes the following steps: Batching and plasticizing: Set the raw material usage ratio in the control system of the biaxially stretched film production line, and then the batching system will automatically convey the dried raw materials of each layer to the extruder according to the input ratio. After melting and plasticizing in the extruder, the melt enters the die through the runner and distributor. Sheet casting: After being extruded from the die, the melt immediately contacts the cooling roll to form a thick sheet. Longitudinal stretching: The thick sheet is heated to the set temperature by multiple groups of preheating rolls, starts longitudinal stretching, and then is shaped. Transverse stretching: After preheating the thick sheet that has been longitudinally stretched to the set temperature, start transverse stretching, and after transverse stretching, carry out shaping and cooling treatment. Traction and winding: The multi-layer structured film output from the transverse stretching unit enters the traction unit, and after thickness measurement and corona treatment, it enters the winding unit to obtain the master roll; Slitting: The master roll that has undergone aging treatment is slit to obtain film rolls of specified width and length.

10. The preparation method of the BOPP matte film with optimized cutting performance based on paper-plastic lamination according to claim 9, characterized in that, Melting and extrusion temperature of the matte layer: 200 - 260 °C; Melting and extrusion temperature of the core layer and the lower surface layer: 230 - 260 °C; In the process of the melt contacting the cooling roll, the temperature of the quenching water and the cooling roll: 15 - 50 °C; Temperature of the longitudinal stretching zone: 90 - 130 °C; Temperature of the transverse stretching zone: 155 - 165 °C; Longitudinal stretching ratio: 4.5 - 5.5 times; Transverse stretching ratio: 8 - 10 times; Corona power factor of the matte layer: 20 - 25 W·min / m.

Images