A release film

Abstract

The present invention relates to the technical field of release films, and particularly relates to a release film, which comprises an upper surface layer, an intermediate layer and a lower surface layer. The intermediate layer comprises poly(4-methyl-1-pentene), poly(α-olefin), polyurethane, a crosslinking agent and a compatibilizer, and the intermediate layer takes polyurethane as a skeleton and forms a network structure through reaction with the crosslinking agent. The release film provided by the present invention has excellent peelability and conformability; in addition, the release film provided by the present invention does not require coating, is environmentally friendly, and has a simple process.

Description

Technical Field

[0001] The present invention relates to the technical field of functional films, and particularly to a preparation method of a release film for a multi-layer circuit board lamination process. Background Art

[0002] In the process of manufacturing flexible printed circuit boards (FPCs), multiple film materials or sheet materials need to be laminated together by heating and pressurizing. ① To prevent adhesion between the metal plate and the film material or sheet material during the high-temperature and high-pressure lamination process, a release film is usually used between the metal plate and the material to be laminated. ② There are uneven surfaces on the FPC circuit surface. ③ To connect the FPC to other electrical components, it is necessary to expose its connection points in advance. The adhesive used in the lamination process melts during the high-temperature and high-pressure process and easily flows to the exposed parts.

[0003] To meet the requirement of ① and achieve a relatively low bonding force between the metal plate and the FPC, common solutions include using paper, PET, PBT on the outer layer and coating them with fluorine-based or silicon-based release agents, or using materials with low surface tension such as PTFE (polytetrafluoroethylene), tetrafluoroethylene-hexafluoropropylene copolymer, polyolefin modified with fluorine-based materials, polymethylpentene or copolymer. Currently, the release film made mainly from TPX (4-methyl-1-pentene polymer) produced by Mitsui of Japan has the most commercialization or the most patents.

[0004] To meet the requirement of ②, the release film should have good shape adhesion at the lamination temperature, that is, it can closely adhere to the FPC surface even in uneven places.

[0005] To meet the requirement of ③, the release film needs to have good glue resistance (that is, during the lamination process, the release film enters according to the shape of the exposed holes to prevent the adhesive from flowing to the exposed connection points). The common solution is to use soft materials in the core layer or the layer connected to the outer layer. CN101479327A uses polyolefins with a Vicat softening point of 50 - 150 °C in the core layer: poly-α-olefin, EMA, EMMA, EAA, EMAA; CN109466124A uses PMMA, PE and other soft materials in the core layer; CN108235594A adopts an ABCBA five-layer structure, and layer B uses one of EMMA / EMA / EVA, as well as TPX, PE and PP; CN108215370A and CN108221477A adopt an ABC three-layer structure, and layer B uses a combination of EMMA, PE and PP; CN112622312A adopts an ABC three-layer structure, layer B uses, and the intermediate functional layer contains at least one soft resin with a melting point below 180 °C and 20 - 70 wt% of soft materials, and the soft resin is selected from polymers polymerized from at least one olefin among ethylene, propylene, butene, pentene, hexene and methylpentene.

[0006] CN101479327A and CN112622312A respectively disclose a release film. During the product design process, in order to achieve the followability of the uneven surface of the printed circuit board and at the same time have excellent cushioning properties, a large amount of polyolefin soft resin with a melting point lower than 180 °C or a Vicat softening point between 50 and 150 °C is used in its core layer. This will cause the phenomenon that the raw materials of the core layer of the release film leak out from the edge of the release film during the lamination process using high temperature and high pressure (temperature 180 °C, pressure 14 MPa) for multi-layer FPC, resulting in contamination of the lamination equipment and affecting the process efficiency.

[0007] The present invention adjusts the core layer formula to reduce the probability of raw material melting and leakage of the core layer during the high temperature and high pressure process. Summary of the Invention

[0008] In view of the above-mentioned drawbacks of the prior art, the present invention provides a release film. The release film provided by the present invention has excellent peelability and adhesion; in addition, the release film provided by the present invention does not require coating, is environmentally friendly, and has a simple process.

[0009] Technical Solution

[0010] To achieve the above object, the present invention is realized through the following technical solutions:

[0011] The present invention provides a release film, which includes an upper surface layer, an intermediate layer, and a lower surface layer. The intermediate layer includes poly(4-methyl-1-pentene), poly(α-olefin), polyurethane, a crosslinking agent, and a compatibilizer, and the intermediate layer forms a network structure through reaction with the crosslinking agent with polyurethane as the backbone.

[0012] Further, both the upper surface layer and the lower surface layer are composed of at least one material selected from poly(4-methyl-1-pentene), copolymer of 4-methyl-1-pentene and α-olefin, homopolymer or copolymer of α-olefin.

[0013] Further, the precursors of the hard segment of the polyurethane include at least one or more of toluene diisocyanate, diphenyl diisocyanate, naphthalene diisocyanate, methylene diphenyl diisocyanate, xylene diisocyanate, and their oligomers.

[0014] Further, the precursors of the soft segment of the polyurethane include at least one or more of polyethylene adipate, polybutylene adipate, polycaprolactone diol, polycarbonate diol, acrylic polyol ester, and polybutadiene polyol ester.

[0015] Further, the polyurethane is an aromatic polyurethane.

[0016] Further, the polyurethane has a density of 0.6 to 2.0 g / cm 3 , a relative molecular mass of 1,000 to 1,000,000, a melt index of 0.1 to 100 g / 10 min (test conditions: 190 °C, 2.16 kg), a Shore hardness of 05A to 90D, and a modulus of elasticity of 10 to 1,000 Mpa.

[0017] Further, the crosslinking agent is at least one or more of polyisocyanates, polyamines, polyols, polyglycidyl ethers, and polyoxyethylenes;

[0018] The compatibilizer includes at least one or more of ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-acrylic acid copolymer, hydrogenated styrene-ethylene / butene-styrene block copolymer, thermoplastic polyester elastomer, maleic anhydride grafted polyolefin, and copolymer of ethylene and α-olefin with eight or more carbon atoms.

[0019] Further, by mass fraction, both the upper surface layer and the lower surface layer are composed of at least one material of poly(4-methyl-1-pentene) (75%-100%) and copolymer of 4-methyl-1-pentene and α-olefin (0-25%), and homopolymer or copolymer of α-olefin (0-25%).

[0020] Further, by mass fraction, the intermediate layer includes 20-70% of poly(4-methyl-1-pentene), 10-60% of poly-α-olefin, 5-40% of polyurethane, 0.1-10% of compatibilizer, and 0.01-10% of crosslinking agent.

[0021] A production process of a release film, the preparation steps of which include dust removal of raw material particles - weighing, mixing and conveying of raw material particles - melt extrusion by an extruder - confluence by a three-layer coextrusion distributor - extrusion by a slit die head - cooling and forming by a cooling roll - trimming of edge materials - online thickness measurement - CCD defect detection - winding.

[0022] For the upper and lower surface layers, during the single-screw extrusion process of their materials, the temperature of the feeding section is set between 150 and 220 °C, and the temperatures of the plasticizing section and the metering section are set between 240 and 290 °C. For the intermediate layer, its material is extruded using a twin-screw extruder. The temperature of its conveying section is set between 40 and 150 °C, and the temperature of the melting and plasticizing section is set between 160 and 260 °C. The temperatures of the distributor and the slot die head are set between 220 and 290 °C, and the set temperature of the slot die head is 5 - 20 °C lower than the set temperature of the distributor. In the stage of the release film cooling and forming, there are a total of three independent cooling rollers, and their set temperatures are between 30 and 70 °C. The set temperatures of the second and third cooling rollers are the same and are 5 - 20 °C lower than the set temperature of the first cooling roller. In order to fully cool the release film, a negative pressure adsorption and electrostatic edge fixing device is installed between the slot die head and the first cooling roller, so that the release film fully adheres to the surface of the first cooling roller. The power of the negative pressure adsorption device is set between 20 and 60%. The voltage of the electrostatic edge fixing device is between 5 and 18 KV. The X-ray thickness gauge is linked with the automatic slot die head, and the die orifice gap of the slot die head is automatically adjusted online according to the measured product thickness to control the average error of the product thickness within 2%. In addition, according to the thickness and production speed of the product, the tension and pressure of the winding are adjusted and controlled within 100 N / m.

[0023] Advantageous Effects

[0024] The technical solution provided by the present invention has the following advantageous effects compared with the known public technology:

[0025] 1. By chemically cross-linking the intermediate layer of polyurethane to form a network structure, the present invention can effectively prevent the raw materials of the core layer of the release film from melting and leaking out from the edge of the release film during the lamination process of multi-layer FPC using high temperature and high pressure (temperature 180 °C, pressure 12 MPa), reduce the risk of polluting the lamination equipment, and improve the process efficiency. At the same time, the excellent flexibility of polyurethane can endow the release film with good glue resistance.

[0026] 2. The release film provided by the present invention has excellent peelability and adhesiveness; in addition, the release film provided by the present invention does not require coating, is environmentally friendly, and has a simple process. Brief Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 It is a schematic structural diagram of the release film described in the present invention;

[0029] Figure 2 This is the process flow chart for the preparation of the release film of the present invention;

[0030] The upper surface layer 1, the intermediate layer 2, and the lower surface layer 3. Detailed implementation manners

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] The present invention will be further described below with reference to the embodiments.

[0033] A release film, which includes an upper surface layer 1, an intermediate layer 2, and a lower surface layer 3. The intermediate layer 2 includes poly(4-methyl-1-pentene), poly(α-olefin), polyurethane, a crosslinking agent, and a compatibilizer, and the intermediate layer 2 has a polyurethane backbone and forms a network structure through reaction with the crosslinking agent.

[0034] Both the upper surface layer 1 and the lower surface layer 3 are composed of at least one of poly(4-methyl-1-pentene), a copolymer of 4-methyl-1-pentene and α-olefin, a homopolymer or copolymer of α-olefin.

[0035] The precursors of the hard segments of the polyurethane include at least one or more of toluene diisocyanate, diphenyl diisocyanate, naphthalene diisocyanate, methylene diphenyl diisocyanate, xylene diisocyanate, and their oligomers.

[0036] The precursors of the soft segments of the polyurethane include at least one or more of polyethylene adipate, polybutylene adipate, polycaprolactone diol, polycarbonate diol, acrylic polyol ester, and polybutadiene polyol ester.

[0037] The polyurethane is an aromatic polyurethane.

[0038] The polyurethane has a density of 0.6 - 2.0 g / cm 3 , a relative molecular mass of 1000 - 1000000, a melt index of 0.1 - 100 g / 10 min (test conditions: 190 °C, 2.16 kg), a Shore hardness of 05A - 90D, and an elastic modulus of 10 - 1000 Mpa.

[0039] The crosslinking agent is at least one or more of polyisocyanates, polyamines, polyols, polyglycidyl ethers, and polyoxyethylenes;

[0040] The compatibilizer includes at least one or more of ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-acrylic acid copolymer, hydrogenated styrene-ethylene / butene-styrene block copolymer, thermoplastic polyester elastomer, maleic anhydride grafted polyolefin, and copolymer of ethylene and α-olefin with eight or more carbon atoms.

[0041] By mass fraction, both the upper surface layer 1 and the lower surface layer 3 are composed of at least one material of 75%-100% of poly-4-methyl-1-pentene, 0-25% of copolymer of 4-methyl-1-pentene and α-olefin, and 0-25% of homopolymer or copolymer of α-olefin.

[0042] By mass fraction, the intermediate layer 2 includes 20-70% of poly-4-methyl-1-pentene, 10-60% of poly-α-olefin, 5-40% of polyurethane, 0.1-10% of compatibilizer, and 0.01-10% of crosslinking agent.

[0043] A production process of a release film, the preparation steps of which include dust removal of raw material particles - weighing, mixing and conveying of raw material particles - melt extrusion by an extruder - confluence by a three-layer co-extrusion distributor - extrusion by a slit die head - cooling and forming by a cooling roll - trimming of edge materials - online thickness measurement - CCD defect detection - winding.

[0044] For the upper and lower surface layers, during the single-screw extrusion process of their materials, the temperature of the feeding section is set between 150 and 220 °C, and the temperatures of the plasticizing section and the metering section are set between 240 and 290 °C. For the intermediate layer, its materials are extruded by a twin-screw extruder, the temperature of its conveying section is set between 40 and 150 °C, and the temperature of the melting and plasticizing section is set between 160 and 260 °C. The temperatures of the distributor and the slit die head are set between 220 and 290 °C, and the set temperature of the slit die head is 5-20 °C lower than that of the distributor. During the cooling and forming stage of the release film, there are three independent cooling rolls, the set temperature of which is between 30 and 70 °C, and the set temperatures of the second and third cooling rolls are the same, 5-20 °C lower than that of the first cooling roll. In order to fully cool the release film, a negative pressure adsorption and electrostatic edge fixing device is installed between the slit die head and the first cooling roll, so that the release film fully adheres to the surface of the first cooling roll. The power of the negative pressure adsorption device is set between 20 and 60%. The voltage of the electrostatic edge fixing device is between 5 and 18 KV. The X-ray thickness gauge is linked with the automatic slit die head, and the die gap of the slit die head is automatically adjusted online according to the measured product thickness, and the average error of the product thickness is controlled within 2%. In addition, according to the thickness and production speed of the product, the tension and pressure of winding are adjusted and controlled within 100 N / m.

[0045] (1) Preparation of Release Film

[0046] Example 1:

[0047] The upper and lower surface layer formulations are 100% by mass fraction of poly(4-methyl-1-pentene); the middle layer formulation is 15% by mass fraction of poly(4-methyl-1-pentene), 20% polyurethane, 10% ethylene-vinyl acetate copolymer, 54.45% polypropylene, 0.5% pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 0.05% of 1,5-naphthalene diisocyanate. The total thickness is 150 μm, and the layer ratio of the upper, middle, and lower layers is 1:6:1.

[0048] Example 2:

[0049] The upper and lower surface layer formulations are 100% by mass fraction of poly(4-methyl-1-pentene); the middle layer formulation is 15% by mass fraction of poly(4-methyl-1-pentene), 20% polyurethane, 10% ethylene-vinyl acetate copolymer, 54.4% polypropylene, 0.5% pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 0.1% of 1,5-naphthalene diisocyanate. The total thickness is 150 μm, and the layer ratio of the upper, middle, and lower layers is 1:6:1.

[0050] Example 3:

[0051] The upper and lower surface layer formulations are 100% by mass fraction of poly(4-methyl-1-pentene); the middle layer formulation is 15% by mass fraction of poly(4-methyl-1-pentene), 20% polyurethane, 10% ethylene-vinyl acetate copolymer, 54.2% polypropylene, 0.5% pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 0.3% of 1,5-naphthalene diisocyanate. The total thickness is 150 μm, and the layer ratio of the upper, middle, and lower layers is 1:6:1.

[0052] Example 4:

[0053] The upper and lower surface layer formulations are 100% by mass fraction of poly(4-methyl-1-pentene); the middle layer formulation is 15% by mass fraction of poly(4-methyl-1-pentene), 20% polyurethane, 10% ethylene-vinyl acetate copolymer, 54% polypropylene, 0.5% pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 0.5% of 1,5-naphthalene diisocyanate. The total thickness is 150 μm, and the layer ratio of the upper, middle, and lower layers is 1:6:1.

[0054] Example 5:

[0055] The upper and lower surface layer formulations are 100% by mass fraction of poly(4-methyl-1-pentene); the middle layer formulation is 15% by mass fraction of poly(4-methyl-1-pentene), 20% of polyurethane, 10% of ethylene-vinyl acetate copolymer, 53.5% of polypropylene, 0.5% of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 1% of 1,5-naphthalene diisocyanate. The total thickness is 150 μm, and the layer ratio of the upper, middle, and lower layers is 1:6:1.

[0056] Comparative Example 1:

[0057] The upper and lower surface layer formulations are 100% by mass fraction of poly(4-methyl-1-pentene); the middle layer formulation is 15% by mass fraction of poly(4-methyl-1-pentene), 20% of polyurethane, 10% of ethylene-vinyl acetate copolymer, 54.5% of polypropylene, 0.5% of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. The total thickness is 150 μm, and the layer ratio of the upper, middle, and lower layers is 1:6:1.

[0058] Comparative Example 2:

[0059] The upper and lower surface layer formulations are 100% by mass fraction of poly(4-methyl-1-pentene); the middle layer formulation is 15% by mass fraction of poly(4-methyl-1-pentene), 10% of ethylene-vinyl acetate copolymer, 73.5% of polypropylene, 0.5% of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 1% of 1,5-naphthalene diisocyanate. The total thickness is 150 μm, and the layer ratio of the upper, middle, and lower layers is 1:6:1.

[0060] Comparative Example 3:

[0061] The upper and lower surface layer formulations are 100% by mass fraction of poly(4-methyl-1-pentene); the middle layer formulation is 15% by mass fraction of poly(4-methyl-1-pentene), 10% of ethylene-vinyl acetate copolymer, 74% of polypropylene, 0.5% of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 0.5% of 1,5-naphthalene diisocyanate. The total thickness is 150 μm, and the layer ratio of the upper, middle, and lower layers is 1:6:1.

[0062] Among them, in Examples 1 - 5 and Comparative Examples 1 - 3:

[0063] The poly(4-methyl-1-pentene) is selected from RT18 of Mitsui Chemicals;

[0064] The polyurethane is selected from 60DT3 produced by Lubrizol;

[0065] Polyethylene-vinyl acetate copolymer, selected for EVA 2518 produced by Hanwha Total Petrochemical;

[0066] Polypropylene, selected for CF330 produced by Hanwha Total Petrochemical;

[0067] Pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], selected for antioxidant 1010 produced by BASF;

[0068] 1,5-Naphthalene diisocyanate, selected for Hangzhou Chongshun Chemistry.

[0069] In addition, the preparation process flows of the release films in Examples 1-5 and Comparative Examples 1-3 are the same, which are specifically as follows:

[0070] Dust removal of raw material particles - weighing, mixing and conveying of raw material particles - melt extrusion by an extruder - confluence by a three-layer coextrusion distributor - extrusion by a slot die head - cooling and forming by a cooling roll - trimming of edge materials - on-line thickness measurement - CCD defect detection - winding.( Figure 2 )

[0071] For the upper and lower surface layers, during the single-screw extrusion process of their materials, the temperature of the feeding section is set at 200 °C, and the temperatures of the plasticizing section and the metering section are set at 260 °C. For the middle layer, its material is extruded using a twin-screw extruder, the temperature of its conveying section is set at 90 °C, and the temperature of the melting and plasticizing section is set at 200 °C. The temperature of the distributor is set at 250 °C, and the temperature of the slot die head is set at 240 °C.

[0072] During the cooling and forming stage of the release film, there are a total of three independent cooling rolls. The temperature of the first cooling roll is set at 60 °C, and the temperatures of the second and third cooling rolls are the same, and their set temperature is 45 °C.

[0073] In order to fully cool the release film, a negative pressure adsorption and electrostatic edge fixing device is installed between the slot die head and the first cooling roll, so that the release film fully adheres to the surface of the first cooling roll. The power of the negative pressure adsorption device is set at 40%. The voltage of the electrostatic edge fixing device is between 12 KV. The X-ray thickness gauge is linked with the automatic slot die head, and the die gap of the slot die head is automatically adjusted online according to the measured product thickness, and the average error of the product thickness is controlled within 2%. In addition, according to the thickness and production speed of the product, the winding tension and pressure are adjusted and controlled within 100 N / m.

[0074] (II) Performance testing of the release film

[0075] The performance testing methods related to the release film are as follows:

[0076] 1. Release property: The release film, protective film, and flexible circuit board are laminated smoothly and reasonably. After lamination under the conditions of 180°C, 14 Mpa, pre-pressing for 10 s, and pressing for 140 s, if the release film can be easily peeled off from its surface without damage, it is qualified.

[0077] 2. Glue overflow property: The release film, protective film, and flexible circuit board are laminated smoothly and reasonably. After lamination under the conditions of 180°C, 14 Mpa, pre-pressing for 10 s, and pressing for 140 s, observe the end face of the laminated release film with a microscope. If the length of the glue extruded from the middle layer is less than 1 mm, it is qualified.

[0078] 3. Glue resistance property: The release film, protective film, and flexible circuit board are laminated smoothly and reasonably. After lamination under the conditions of 180°C, 14 Mpa, pre-pressing for 10 s, and pressing for 140 s, tear off the release film, and observe with a microscope. If the size of the glue overflowing at the intersection of the edge of the protective film at the reserved hole of the laminated flexible circuit board and the terminal interface at the reserved hole is less than 0.1 mm, it is qualified.

[0079] 4. Thermal shrinkage rate: Take a 100 mm X 100 mm square sample, place it in an oven at 180°C for 30 min, take out the sample and cool it to room temperature, and measure the size of the sample in the MD direction.

[0080]

[0081] Release property Resistance to glue Glue overflow property MD shrinkage rate (%) Example 1 Qualified Qualified Unqualified 1.1 Example 2 Qualified Qualified Qualified 0.8 Example 3 Qualified Qualified Qualified 0.2 Example 4 Qualified Qualified Qualified 0.2 Example 5 Qualified Qualified Qualified 0.2 Comparative example 1 Qualified Qualified Unqualified 2.8 Comparative example 2 Qualified Unqualified Unqualified 2.0 Comparative example 3 Qualified Unqualified Unqualified 2.0

[0082] From the test results in the above table, it can be seen that 1,5-naphthalene diisocyanate and polyurethane have a greater impact on the performance of the release film. Among them, from Examples 1 - 5 and Comparative Example 1, it can be seen that when the mass fraction of 1,5-naphthalene diisocyanate is between 0 - 0.05%, the glue overflow property is unqualified; from Examples 1 - 5 and Comparative Examples 2 - 3, it can be seen that when polyurethane is not added, both its glue resistance property and glue overflow property are unqualified.

[0083] It can be seen that by chemically cross-linking the middle layer of polyurethane to form a network structure, the present invention can effectively prevent the raw materials of the core layer of the release film from leaking out from the edge of the release film during the lamination process of multi-layer FPC using high temperature and high pressure (temperature 180°C, pressure 12 MPa), reduce the risk of polluting the lamination equipment, and improve the process efficiency. At the same time, the excellent flexibility of polyurethane can endow the release film with good glue resistance property.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A release film, characterized in that, It includes an upper surface layer, an intermediate layer and a lower surface layer. By mass fraction, the intermediate layer includes 15% of poly(4-methyl-1-pentene), 10-60% of polyalphaolefin, 5-40% of polyurethane, 0.1-10% of compatibilizer and 0.5-10% of crosslinking agent, and the intermediate layer takes polyurethane as the skeleton and forms a network structure through reaction with the crosslinking agent; The crosslinking agent adopts polyisocyanates; The polyurethane has a density of 0.6 to 2.0 g / cm 3 , a relative molecular mass of 1,000 to 1,000,000, a melt index of 0.1 to 100 g / 10 min, a Shore hardness of 05A to 90D, and a modulus of elasticity of 10 to 1,000 Mpa; Both the upper surface layer and the lower surface layer are composed of at least one material among poly(4-methyl-1-pentene), copolymer of 4-methyl-1-pentene and alpha-olefin, homopolymer of alpha-olefin and copolymer of alpha-olefin.

2. An anti-adhesive film according to claim 1, characterized in that, The precursors of the hard segments of the polyurethane include at least one or more of toluene diisocyanate, diphenyl diisocyanate, naphthalene diisocyanate, methylene diphenyl diisocyanate, xylene diisocyanate and their oligomers.

3. An anti-adhesive film according to claim 1, characterized in that, The precursors of the soft segments of the polyurethane include at least one or more of polyethylene adipate, polybutylene adipate, polycaprolactone diol, polycarbonate diol, acrylic polyol ester and polybutadiene polyol ester.

4. A release film according to claim 1, wherein The polyurethane is an aromatic polyurethane.

5. The release film according to claim 1, wherein The compatibilizer includes at least one or more of ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-acrylic acid copolymer, hydrogenated styrene-ethylene / butene-styrene block copolymer, thermoplastic polyester elastomer, maleic anhydride grafted polyolefin, copolymer of ethylene and alpha-olefin with eight or more carbon atoms.

6. A release film according to claim 1, wherein, By mass fraction, both the upper surface layer and the lower surface layer are composed of 75%-100% of poly(4-methyl-1-pentene), 0-25% of copolymer of 4-methyl-1-pentene and alpha-olefin, 0-25% of homopolymer of alpha-olefin or copolymer of alpha-olefin.

7. The manufacturing process of a release film as described in claim 1, characterized in that, Its preparation steps include dust removal of raw material particles - weighing, mixing and conveying of raw material particles - melt extrusion by an extruder - confluence by a three-layer coextrusion distributor - extrusion by a slit flat die head - cooling and forming by a cooling roll - trimming of side materials - online thickness measurement - CCD defect detection - winding.

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