A pet matte film with mountainous surface and a preparation method thereof

Abstract

The application discloses a PET matte film with mountainous surface and a preparation method thereof, and relates to the technical field of matte films.The preparation method of the PET matte film with mountainous surface is as follows: after surface layer matte particles and intermediate layer materials are melt co-extruded, calender setting is carried out to form a sheet; the raw material of the surface layer matte particles comprises a first resin, a second resin and an additive, the first resin is any one or a combination of two of polyethylene terephthalate and polyethylene terephthalate copolymer, and the second resin is any one or a combination of multiple of nylon, polyolefin and styrene resin; after the sheet is sequentially subjected to longitudinal stretching, transverse stretching and heat setting, the PET matte film with mountainous surface is prepared.The PET matte film with mountainous surface can form a matte surface with mountainous surface in an orderly concave-convex manner on the surface of the PET matte film, has a smooth hand feeling, and solves the problem of poor hand feeling of the PET matte film prepared by adding inorganic small particle substances to a surface layer in a traditional manner.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of matte film, in particular to a PET matte film with mountainous surface and a preparation method thereof. BACKGROUND

[0002] The matte film is also called the matt film and the extinction film, which can give people soft, comfortable and hazy visual effect. The matte film is usually produced by using PP, PE and PET resins through the processes of biaxial stretching or blowing film and casting.

[0003] At present, most of the PET matte films are prepared by using the multilayer co-extrusion biaxial stretching process. The PET matte film with certain matte characteristics is prepared by adding inorganic granular substances (such as silicon dioxide) with the size of 2-15 microns in the surface layer. The principle of forming the matte surface is mainly because the inorganic particles form enough protruding points on the surface. When the light is irradiated on the surface, the scattered light is generated, thereby giving people the matte effect. The PET matte film produced by using the process route has the protruding part (i.e. the inorganic particles protruding from the surface of the surface layer) and the concave part which are not smoothly connected, and the concave part is flat. The surface of the matte film made in this way has poor hand feeling and is rough, and the touch is not smooth enough. If the existing PET matte film is used as the release film of the surface mold, the surface of the object transferred from the surface of the release film will present a small point-shaped pit, and the hand feeling is also poor. SUMMARY

[0004] In view of the problems in the background art, the present application aims to provide a preparation method of a PET matte film with mountainous surface, which can form a concave-convex mountainous matte surface on the surface of the PET matte film, and has smooth hand feeling, thereby solving the problem of poor hand feeling of the PET matte film prepared by adding inorganic small particle substances in the surface layer.

[0005] Another object of the present application is to provide a PET matte film with mountainous surface prepared by the above method.

[0006] To achieve the above object, the present application adopts the following technical scheme:

[0007] A preparation method of a PET matte film with mountainous surface, comprising the following steps:

[0008] (1) melt-extruding the surface matte particles and the intermediate layer material to form a sheet, wherein the raw materials of the surface matte particles include a first resin, a second resin and an additive, the first resin is any one or a combination of polyethylene terephthalate and polyethylene terephthalate copolymer, and the second resin is any one or a combination of nylon, polyolefin and styrene resin;

[0009] (2) stretching the sheet in the longitudinal direction, then in the transverse direction, and then heat setting to obtain a PET matte film with mountain-shaped surface.

[0010] Preferably, in the step (1), the surface matte particles include first surface matte particles and second surface matte particles, and the raw materials of the first surface matte particles and the second surface matte particles are the same.

[0011] The preparation method of the step (1) is as follows: melt-extruding the first surface matte particles, the intermediate layer material and the second surface matte particles to form a sheet.

[0012] Preferably, in the step (2), the stretching ratio of the sheet in the longitudinal direction is 3-5 times, and the stretching temperature is 75-85℃.

[0013] Preferably, in the step (2), the stretching ratio of the sheet in the transverse direction is 7-10 times, and the stretching temperature is 110-130℃.

[0014] The heat setting temperature of the sheet after transverse stretching is 200-250℃.

[0015] Preferably, in the step (1), the surface matte particles include the following raw materials in mass fraction: 50-90 parts of the first resin, 10-50 parts of the second resin and 0.1-5 parts of the additive.

[0016] Further, before the step (1), the preparation step of the surface matte particles is further included, and the preparation method of the matte particles is as follows: uniformly stirring and mixing the first resin, the second resin and the additive at a stirring speed of 100-300 r / min for 1-10 min to obtain a mixture; feeding the mixture into a double-screw extruder, and fully plasticizing and fusing the mixture under high temperature and high-speed shearing action of the screw, then extruding a strip through a porous die, cooling the strip through cooling water, cutting the cooled strip in a pelletizer to obtain the surface matte particles.

[0017] Preferably, the raw materials of the intermediate layer material include polyethylene terephthalate and / or polyethylene terephthalate copolymer.

[0018] The PET matte film with the mountainous surface is prepared by the preparation method of the PET matte film with the mountainous surface.

[0019] The PET matte film with the mountainous surface has the following effects: the first resin and the second resin in the surface matte particles are shrunk to different degrees after melting and cooling, and the shrinkage difference is generated to make the surface of the final product have a concave-convex shape, so that the matte effect is achieved. The PET matte film with the mountainous surface is prepared by using the surface matte particles as the surface raw material, and the concave-convex mountainous matte surface is formed in the PET matte film after the biaxial stretching process. The surface of the PET matte film prepared by the technical scheme has a continuous concave-convex shape like a mountain, and the hand feeling is smooth. The surface of the object transferred from the surface of the PET matte film has a mountainous matte surface, and the hand feeling is also good. The PET matte film solves the problem of poor hand feeling of the traditional matte PET film prepared by adding inorganic small particles to the surface. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The surface effect diagram of the PET matte film prepared by an embodiment of the present application;

[0021] Figure 2 The surface effect diagram of the PET matte film purchased from the market for Comparative Example 1. DETAILED DESCRIPTION

[0022] The technical scheme of the present application is further described below in combination with the specific embodiments.

[0023] A preparation method of a PET matte film with a mountainous surface, comprising the following steps:

[0024] (1) melt and co-extrude the surface matte particles and the intermediate layer material, and then perform calendering and setting to form a sheet; the raw material of the surface matte particles comprises a first resin, a second resin and an additive, the first resin is any one or a combination of two of polyethylene terephthalate and polyethylene terephthalate copolymer, and the second resin is any one or a combination of multiple of nylon, polyolefin and styrene resin;

[0025] (2) sequentially perform longitudinal stretching, transverse stretching and heat setting on the sheet to prepare the PET matte film with the mountainous surface.

[0026] It is worth mentioning that the surface layer matte particles include the first resin and the second resin, and the first resin and the second resin will shrink to different degrees after melting and cooling, resulting in shrinkage difference, so that the surface layer of the final product has concave-convex shape, thereby achieving the matte effect. The above surface layer matte particles are used as the surface layer raw material in the technical solution, and after the biaxial stretching process, the PET matte film has a concave-convex mountain-shaped matte surface on the surface of the surface layer (as shown in Figure 1 The surface of the PET matte film prepared by the technical solution is a continuous mountain-shaped concave-convex surface, and the hand feeling is smooth. The PET matte film is applied in the release film of the surface mold, and the surface of the object transferred from the surface of the PET matte film also has a mountain-shaped matte surface, and the hand feeling is also good. The surface of the PET matte film prepared by the technical solution has a smooth surface.

[0027] Specifically, the technical solution uses surface layer matte particles including two kinds of mixed resins as the surface layer raw material to prepare the PET matte film. The mechanism is based on the fact that the melt specific gravity of the resin is usually different from the specific gravity after cooling. Usually, the specific gravity after cooling increases. The difference between the two is set as D value. By selecting resins with a certain difference (such as a difference of 0.2-0.5) and having good compatibility with PET resin, good film production performance, and other specific requirements, two or more of these resins are prepared into a mixed resin. When the mixed resin is used as the surface layer material to prepare the film, the part of the mixed resin with a large D value will shrink more and cause concave, thereby forming a PET matte film with a continuous mountain-shaped concave-convex surface.

[0028] Further, in the step (1), the surface layer matte particles include first surface layer matte particles and second surface layer matte particles, and the raw materials of the first surface layer matte particles and the second surface layer matte particles are the same.

[0029] The preparation method of the step (1) is as follows: melt co-extrusion of the first surface layer matte particles, the intermediate layer material, and the second surface layer matte particles, and then calendering and setting to form a sheet.

[0030] The PET matte film in the technical solution is prepared by melt co-extrusion. The matte layer can be prepared only on one surface of the PET matte film, or the matte layer can be provided on both surfaces of the PET matte film. When the double-sided matte layer is needed, the first surface layer matte particles, the intermediate layer material, and the second surface layer matte particles are respectively melted, plasticized, and extruded by three extruders, converged in the same mold, and then flowed out of the mold. The melt is cooled by a casting roll to form a sheet with a certain thickness. Then, the sheet is sequentially subjected to longitudinal stretching, transverse stretching, and heat setting to obtain a PET matte film with a mountain-shaped surface on both surfaces.

[0031] Further, in the step (2), the stretching ratio of the sheet in the longitudinal direction is 3-5 times, and the stretching temperature is 75-85℃.

[0032] Further, in the step (2), the stretching ratio of the sheet in the longitudinal direction is 3-5 times, and the stretching temperature is 75-85℃.

[0033] The temperature for heat setting of the sheet after transverse stretching is 200-250℃.

[0034] It is worth pointing out that the PET matte film production process in the present technical solution is as follows:

[0035] The prepared surface matte particles are put into the extruder for melting and plasticizing, and then pass through a rapid filtering screen, a metering pump, a hanger multi-layer die, a calender setting, a longitudinal stretching machine, a cooling setting device, a traction device, a transverse stretching machine, an edge cutting device, a traction device, and a winding device to produce the PET matte film.

[0036] In the above process, the surface matte particles are first fully melted and plasticized, and then cooled and set during calender setting. In this process, the surface matte particles are rapidly cooled and set from a molten state (about 250-300℃) to a sheet (about 25-50℃), and then undergo longitudinal stretching, transverse stretching (the longitudinal stretching ratio is 3-5 times, and the stretching temperature is 75-85℃; the transverse stretching ratio is 7-10 times, and the stretching temperature is 110-130℃), and heat setting (the maximum temperature can reach 250℃). During the heat process of stretching and setting, the crystalline resin in the surface matte particles of the matte layer generates a large amount of crystals and uniformly disperses in the surface layer (i.e., the matte layer). The crystalline regions form depressions due to the higher density, and a large number of depressions are densely distributed on the surface and are closely connected. After longitudinal and transverse stretching, the depressions are more uniformly and finely distributed, forming the required matte surface like mountain ranges.

[0037] Further, in the step (1), the surface matte particles include the following raw materials in mass fractions: 50-90 parts of the first resin, 10-50 parts of the second resin, and 0.1-5 parts of the auxiliary agent.

[0038] Preferably, the melting temperature of the first resin is 200-300℃, and the intrinsic viscosity is 0.65-5. The intrinsic viscosity of the first resin is set according to the biaxial stretching process. If the intrinsic viscosity of the first resin is too low, below 0.65, the flowability of the first resin is too high, the melt strength is poor, the extrusion is unstable, and it is difficult to form a film. If the intrinsic viscosity of the first resin is too high, above 5, the flowability of the first component resin is very low, it is difficult to smoothly extrude, the equipment load is large during melting, and it is also not conducive to film formation. Therefore, the intrinsic viscosity needs to be controlled in the range of 0.65-5.

[0039] It is worth pointing out that the second resin is any one or a combination of nylon, polyolefin and styrene resin, the nylon used in the second resin is any one or a combination of aliphatic nylon, aromatic nylon and copolymer thereof, the relative viscosity of the nylon is 1-10; the polyolefin is any one or a combination of polypropylene, polyethylene, polybutylene and polypropylene homopolymer, the melt index of the polyolefin is 1-20 g / 10 min under the condition of 230 DEG C and 2.16 kg; the styrene resin is any one or a combination of general purpose polystyrene, MBS resin, SAN resin and impact grade polystyrene. The materials in the above parameter range are selected to meet the requirements of the later biaxial stretching film processing technology, which is beneficial to the stable molding.

[0040] Specifically, the general purpose polystyrene is abbreviated as GPPS; the MBS resin refers to the terpolymer of methyl methacrylate (M), butadiene (B) and styrene (S), and the MBS resin has both processing modification and toughening effect; the SAN resin is Styrene Acrylonitrile, which is a colorless and transparent polypropylene-based engineering plastic with high mechanical strength, and the chemical stability of the SAN resin is good; the impact grade polystyrene is abbreviated as HIPS, and is commonly known as modified benzene.

[0041] Preferably, the auxiliary agent used in the surface layer matte particle is a compatibilizing agent and / or an exchange reaction inhibitor, the compatibilizing agent can be selected from any one of maleic anhydride grafted polyolefin, styrene-maleic anhydride copolymer and polyethylene terephthalate, and the exchange reaction inhibitor is a maleic anhydride-acrylate copolymer. The exchange reaction inhibitor can prevent the exchange reaction of esters (such as polyethylene terephthalate and polyethylene terephthalate) and amides (nylon) from causing molecular chain scission when mixed in a high temperature molten state.

[0042] The surface layer matte particle of the technical solution not only has uniform extinction effect, but also has good high temperature resistance and still has good extinction effect under high temperature conditions, and has the advantages of low screen pressure, less film breaking times and no precipitation due to excellent dispersion performance. The surface layer matte particle is blended by using a high molecular alloy method, the mixing ratio of the first resin and the second resin is high, and no inorganic powder is added in the surface layer matte particle. The miscibility of organic matters is better than that of inorganic powder, so that the surface of the product made of the surface layer matte particle has uniform extinction effect. At the same time, the surface layer matte particle is in a softened and flowing state at high temperature, is easy to pass through the filter screen, and is stable in extrusion without the problem of blocking the filter screen. At the same time, the first resin and the second resin have limited molecular thermal motion ability after cooling, and will not migrate and precipitate like small molecular organic matters.

[0043] Further, the surface layer matte particle includes 50-90 parts of the first resin, 10-50 parts of the second resin, and 0.1-5 parts of the additive. The content of the first resin and the second resin can be set according to the required extinction degree of the product. If the amount of the first resin is less than 50 parts, the extinction effect is not obvious, which cannot meet the user's requirements. If the amount of the first resin is more than 90 parts, the dispersibility and other mechanical properties of the overall material will be poor, which will result in poor extinction uniformity of the PET matte film made of the surface layer matte particle, and the overall effect and quality will be reduced.

[0044] Specifically, the surface layer matte particle is a semi-transparent to light white small cylindrical or flaky particle.

[0045] Further, before the step (1), the preparation step of the surface layer matte particle is further included. The preparation method of the matte particle is as follows: the first resin, the second resin, and the additive are stirred and mixed uniformly at a stirring speed of 100-300 r / min and a stirring time of 1-10 min. After being fully mixed and uniformly mixed, a mixture is obtained. The mixture is put into a double screw extruder. The mixture is fully plasticized and fused under high temperature and high speed shearing action of the screw, and then is extruded into a strip through a porous die. After being cooled by cooling water, a material strip is obtained. The cooled material strip is cut into particles in a pelletizer to obtain the surface layer matte particle.

[0046] It is worth noting that the surface layer matte particle is first prepared by fully mixing the resin components in a high-speed stirrer, and then is prepared by melt plasticizing, extruding, and cooling and cutting in a double screw granulator. The surface layer matte particle can make the PET matte film have a uniform and delicate matte surface layer. At the same time, the surface layer matte particle has good high temperature resistance and still maintains a good matte surface under high temperature (above 120℃).

[0047] Specifically, the preparation method of the surface layer matte particle is as follows:

[0048] (1) The resin prone to moisture absorption in the components is pre-treated by vacuum drying, such as PET, nylon, etc. The drying temperature is 120 degrees, and the drying time is 5-20 hours, so that the moisture is less than 1000 ppm, preventing molecular degradation caused by hydrolysis. The first resin, the second resin, and the additive are added to a high-speed stirrer in a certain ratio, fully mixed at a certain stirring speed and time, and then unloaded for standby to obtain a mixture;

[0049] (2) The mixture obtained in the previous step is fed into the hopper of the twin-screw extruder, and the temperature of each section of the twin-screw extruder barrel is set. The twin-screw extruder is started at a certain speed and feeding begins at the same time. The material is fully plasticized and fused under the high temperature and high-speed shearing action of the screw. After passing through the multi-hole die head, it immediately enters the cooling water for cooling. The cooled material strip is then pulled into the high-speed rotating pelletizer and cut into small particles with uniform shape and color. After drying, it is weighed and packaged for storage to obtain matte surface particles.

[0050] It is worth noting that in the production process of matte surface granules, the mixing speed of the mixer is 100–300 r / min, and the mixing time is 1–10 min. The twin-screw extruder used has a screw diameter of 30–80 mm, an aspect ratio of 35–50, a temperature of 200–300℃, a die temperature of 230–300℃, a feeding speed of 10–60 r / min, a screw speed of 100–300 r / min, a cooling water length of no more than 0.5 m, and a pelletizer speed of 100–300 r / min, resulting in matte surface granules. By setting the above process parameters, a better melting and mixing state can be achieved, ensuring a certain stirring speed, time, screw length-to-diameter ratio, and rotation speed, which is conducive to the full and uniform mixing of materials. Moreover, within the temperature range set by this technical solution, it can be ensured that the materials can be fully melted without high-temperature degradation. Setting a certain cooling water length is beneficial for the cooling and traction of the material strip, while ensuring that the moisture content of the finished masterbatch is not too high, so as to facilitate subsequent film formation processing. This results in the preparation of matte surface granules with the advantages of stable processing performance and good matting uniformity.

[0051] Further explanation: the raw materials of the intermediate layer material include polyethylene terephthalate and / or polyethylene terephthalate copolymer.

[0052] It is worth noting that the raw material for the interlayer of the PET matte film in this technical solution is polyethylene terephthalate (PET) and / or polyethylene terephthalate copolymer (PET copolymer). Compared with PP and PE, PET has higher heat resistance, strength, and stiffness. PET has a melting point of 250-255℃, a tensile strength greater than 190MPa, and a flexural modulus of approximately 4000MPa; while PP has a melting point of 155-165℃, a tensile strength of only 20-30MPa, and a flexural modulus of approximately 1500MPa; PE has a melting point of 100-130℃, a tensile strength of only 12-20MPa, and a flexural modulus of approximately 1000MPa. Therefore, the use of PET and its copolymers as the raw material for the interlayer of this technical solution results in a PET matte film with good heat resistance, high strength, and high stiffness.

[0053] The PET matte film with mountainous surface is prepared by the method for preparing the PET matte film with mountainous surface.

[0054] The technical solutions of the present application are further described below in combination with specific examples.

[0055] Example 1

[0056] The method for preparing the PET matte film with mountainous surface comprises the following steps:

[0057] (1) After the surface matte particles and the intermediate layer material are respectively melt co-extruded, calender setting (cooling setting is adopted) is performed, and in this process, the surface matte particles are rapidly cooled and set from the molten state to form a sheet; according to the mass fraction, the raw materials of the surface matte particles include 71 parts of the first resin (PET), 24 parts of the second resin (nylon) and 4 parts of the auxiliary agent (maleic anhydride-acrylate copolymer);

[0058] (2) After the sheet is sequentially subjected to longitudinal stretching, transverse stretching and heat setting, the PET matte film with mountainous surface is prepared; wherein the stretching multiple of the sheet subjected to longitudinal stretching is 4 times, the stretching temperature is 75℃; the stretching multiple of the sheet subjected to transverse stretching is 8 times, the stretching temperature is 120℃, and the temperature of the sheet subjected to heat setting after transverse stretching is 230℃.

[0059] Example 2

[0060] The method for preparing the PET matte film with mountainous surface comprises the following steps:

[0061] (1) After the surface matte particles and the intermediate layer material are respectively melt co-extruded, calender setting (cooling setting is adopted) is performed, and in this process, the surface matte particles are rapidly cooled and set from the molten state to form a sheet; according to the mass fraction, the raw materials of the surface matte particles include 68 parts of the first resin (PET), 30 parts of the second resin (aromatic nylon MXD-6) and 2 parts of the auxiliary agent (maleic anhydride-acrylate copolymer);

[0062] (2) After the sheet is sequentially subjected to longitudinal stretching, transverse stretching and heat setting, the PET matte film with mountainous surface is prepared; wherein the stretching multiple of the sheet subjected to longitudinal stretching is 5 times, the stretching temperature is 80℃; the stretching multiple of the sheet subjected to transverse stretching is 7 times, the stretching temperature is 110℃, and the temperature of the sheet subjected to heat setting after transverse stretching is 200℃.

[0063] Example 3

[0064] The method for preparing the PET matte film with mountainous surface comprises the following steps:

[0065] (1) melt-extruding the surface matt granules and the intermediate layer material respectively, then carrying out calendering and setting (using cooling setting), in this process the surface matt granules are rapidly cooled and set from the molten state to form a sheet; according to mass fraction, the raw materials of the surface matt granules include 75 parts of the first resin (PET), 22 parts of the second resin (nylon 6-nylon 66 copolymer) and 3 parts of the auxiliary agent (maleic anhydride-acrylate copolymer);

[0066] (2) after sequentially carrying out longitudinal stretching, transverse stretching and heat setting on the sheet, the PET matt film with mountainous surface is prepared; wherein the stretching multiple of the sheet during longitudinal stretching is 3 times, and the stretching temperature is 85°C; the stretching multiple of the sheet during transverse stretching is 10 times, and the stretching temperature is 130°C, and the temperature for heat setting of the sheet after transverse stretching is 250°C.

[0067] Example 4

[0068] The preparation method of the PET matt film with mountainous surface in this example includes the following steps:

[0069] (1) melt-extruding the surface matt granules and the intermediate layer material respectively, then carrying out calendering and setting (using cooling setting), in this process the surface matt granules are rapidly cooled and set from the molten state to form a sheet; according to mass fraction, the raw materials of the surface matt granules include 76 parts of the first resin (polyethylene terephthalate copolymer), 19 parts of the second resin (polypropylene homopolymer) and 5 parts of the auxiliary agent (maleic anhydride grafted polyolefin);

[0070] (2) after sequentially carrying out longitudinal stretching, transverse stretching and heat setting on the sheet, the PET matt film with mountainous surface is prepared; wherein the stretching multiple of the sheet during longitudinal stretching is 4 times, and the stretching temperature is 80°C; the stretching multiple of the sheet during transverse stretching is 8 times, and the stretching temperature is 110°C, and the temperature for heat setting of the sheet after transverse stretching is 220°C.

[0071] Specifically, according to the test method in the national standard GB / T 16958-2008 “Biaxially Oriented Polyester Film for Packaging”, the glossiness and light transmittance of the surface of the PET matt film prepared in Examples 1-4 are respectively tested, and the test results are shown in Table 1.

[0072] Table 1 Test results of Examples 1-4

[0073] Examples Gloss ( % ) Transmittance ( % ) Example 1 16.7 83.2 Example 2 17.1 83.9 Example 3 16.4 82.3 Example 4 16.6 82.8

[0074] As can be seen from the test results in Table 1, the PET matte films prepared in Examples 1-4 have a good matte effect with a gloss of 16.4% to 17.1%. The lower the gloss, the better the matte effect. At the same time, the PET matte films prepared in Examples 1-4 still have good light transmittance while having good matte properties, with a light transmittance of more than 80%.

[0075] Specifically, the surface microstructure of the matte PET film prepared in the examples was observed using an optical microscope, and the surface effect image is shown below. Figure 1 As shown, from Figure 1 As can be seen, the PET matte film prepared in Example 1 forms a textured, mountain-like matte surface with a continuous mountain-like texture and a silky smooth feel.

[0076] Comparative Example 1

[0077] This comparative example uses commercially available matte PET film. The matte effect of this PET matte film is mainly achieved by adding inorganic particulate matter (silica) to the surface layer.

[0078] Specifically, the performance of the comparative example PET matte film was tested. The results showed that the gloss of the comparative example PET matte film was 20.4%, and the light transmittance was 70.1%. Therefore, compared to the PET matte films prepared in Examples 1-4, the comparative example PET matte film has poorer matteness and relatively poorer light transmittance. Furthermore, the surface microstructure of the comparative example PET matte film was observed using an optical microscope, and the surface effect image is shown below. Figure 2 As shown, from Figure 2 As can be seen, the protrusions and recesses on the surface of the PET matte film in this comparative example are not smoothly connected. As a result, the surface of the matte film produced by this method has a poor feel, is rough, and does not have a silky smooth texture.

[0079] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a matte PET film with a mountain-like surface, characterized in that, Includes the following steps: (1) After the surface matte particles and the intermediate layer material are melt-co-extruded, they are calendered and shaped to form a sheet; the raw materials of the surface matte particles include a first resin, a second resin and an additive, wherein the first resin is any one or a combination of two of polyethylene terephthalate and polyethylene terephthalate copolymer, and the second resin is any one or a combination of nylon, polyolefin and styrene resin; (2) After the sheet is stretched longitudinally, stretched laterally and heat-set in sequence, a matte PET film with a mountain-like surface is obtained; In step (2), the longitudinal stretching ratio of the sheet is 3 to 5 times and the stretching temperature is 75 to 85°C; the transverse stretching ratio of the sheet is 7 to 10 times and the stretching temperature is 110 to 130°C; the heat setting temperature of the transversely stretched sheet is 200 to 250°C. The additives used in the matte surface particles are compatibilizers and / or exchange reaction inhibitors. The compatibilizers are selected from maleic anhydride-grafted polyolefins or styrene-maleic anhydride copolymers, and the exchange reaction inhibitors are maleic anhydride-acrylate copolymers.

2. The method for preparing a matte PET film with a mountain-like surface according to claim 1, characterized in that, In step (1), the surface matte particles include a first surface matte particle and a second surface matte particle, and the raw material composition of the first surface matte particle and the second surface matte particle is the same. The preparation method of step (1) is as follows: after the first surface matte particles, the intermediate layer material and the second surface matte particles are melted and co-extruded, they are calendered and shaped to form a sheet.

3. The method for preparing a matte PET film with a mountain-like surface according to claim 1, characterized in that, In step (1), the surface matte particles comprise the following parts by weight of raw materials: 50-90 parts of first resin, 10-50 parts of second resin, and 0.1-5 parts of additives.

4. The method for preparing a matte PET film with a mountain-like surface according to claim 3, characterized in that, Before step (1), the preparation step of the surface matte particles is also included. The preparation method of the matte particles is as follows: the first resin, the second resin and the additives are stirred and mixed evenly at a stirring speed of 100r~300r / min and a stirring time of 1~10min. After being fully mixed evenly, a mixture is obtained. The mixture is fed into a twin-screw extruder. The mixture is fully plasticized and fused under high temperature and high-speed shearing action of the screw. The extruded strip is made through a multi-hole die and cooled with cooling water to obtain a strip. The cooled strip is pelletized in a pelletizer to obtain surface matte particles.

5. The method for preparing a matte PET film with a mountain-like surface according to claim 1, characterized in that, The raw materials for the intermediate layer material include polyethylene terephthalate and / or polyethylene terephthalate copolymer.

6. A matte PET film with a mountain-like surface, characterized in that, It is prepared by the method for preparing a PET matte film with a mountain-like surface as described in any one of claims 1-5.

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