阅读说明：本技术 一种皮革用离型膜及其制备方法 (Release film for leather and preparation method thereof ) 是由 张初强 于 2021-07-09 设计创作，主要内容包括：本发明公开一种皮革用离型膜的制备方法,其包括：制备预涂层涂料；制备离型层涂料；利用电晕处理制备基材；于基材上涂覆预涂层涂料,经固化后构成预涂层,得到预涂基材；采用狭缝涂布方式辅以电子束,将离型层涂料压纹固化于预涂基材上构成离型层,获得皮革用离型膜；还公开一种皮革用离型膜。本发明中的皮革用离型膜包括三层结构：由脂肪族聚氨酯丙酸树脂合成的离型层、水性丙烯酸乳液的预涂层、及已电晕处理的基材,采用辅以电子束直接辊压的方式固化压纹,实现压纹和固化同时进行,解决传统离型膜因基材物理强度的限制而导致产品的平整度和纹路逼真度差的问题,所得产品具有纹路逼真、重复使用率高、及耐溶剂性、表面抗刮性、平整度好的优点。(The invention discloses a preparation method of a release film for leather, which comprises the following steps: preparing a precoating paint; preparing a release layer coating; preparing a base material by using corona treatment; coating a precoating layer coating on a base material, and forming a precoating layer after curing to obtain a precoated base material; embossing and curing the release layer coating on the pre-coated substrate to form a release layer by adopting a slit coating mode and assisting with an electron beam to obtain a release film for leather; also discloses a release film for leather. The release film for leather comprises a three-layer structure: the embossing film is characterized in that a release layer synthesized by aliphatic polyurethane propionic acid resin, a precoating layer of water-based acrylic emulsion and a corona-treated substrate are used for curing embossing in a mode of being assisted by direct rolling of an electron beam, embossing and curing are carried out simultaneously, the problem that the flatness and the line fidelity of a product are poor due to the limitation of the physical strength of the substrate in the traditional release film is solved, and the obtained product has the advantages of line fidelity, high reuse rate, solvent resistance, surface scratch resistance and good flatness.)

1. A preparation method of a release film for leather is characterized by comprising the following steps:

step 1, preparing a precoating paint;

step 2, preparing a release layer coating;

step 3, preparing a base material by using corona treatment;

step 4, coating the precoating coating on the base material, and curing to form a precoating layer to obtain a precoated base material;

and 5, embossing and curing the release layer coating on the pre-coated substrate to form a release layer by adopting a slit coating mode and assisting with an electron beam, so as to obtain the release film for the leather.

2. The method for preparing the release film for leather according to claim 1, wherein in the step 1, the pre-coating paint consists of the following components in parts by weight: 40-60 parts of deionized water, 20-40 parts of water-based acrylic emulsion and 1-10 parts of functional auxiliary agent.

3. The preparation method of the release film for leather according to claim 2, wherein in the step 2, the release layer coating comprises the following components in parts by weight: 30-80 parts of aliphatic polyurethane propionic resin, 30-80 parts of modified epoxy acrylate, 10-80 parts of a monomer agent, 1-5 parts of a functional assistant, 1-5 parts of a release agent and 1-5 parts of a filler.

4. The method for preparing the release film for leather according to claim 3, wherein the release layer coating further comprises 1-5 parts by weight of antistatic particles, and the antistatic particles are carbon nanotube particles, silver powder, nickel powder, copper powder, polythiophene compounds or quaternary phosphonium salt particles.

5. The method for preparing the release film for leather according to claim 4, wherein in the step 3, the corona treatment process parameters are as follows: the high-frequency alternating voltage is 5000-15000V/m²The production speed is 10-30 mpm.

6. The preparation method of the release film for leather according to claim 5, wherein the specific steps of the step 4 are as follows: the precoating coating is applied to the substrate by a dimple or anilox roller and cured by heating at 120 ℃ for 90 seconds to form the precoating layer, thereby obtaining the precoated substrate.

7. The method for preparing the release film for leather according to claim 6, wherein the step 5 specifically comprises the following steps: on electron beam curing equipment, the precoated substrate is guided to a coating device from an unreeling device, a slit coating mode is adopted to coat the release layer coating on the precoated layer to form the release layer, then the release layer is placed in the electron beam curing device, the release layer is subjected to embossing and curing by a pattern roller under electron beams to obtain the release film for leather, and the release film for leather is reeled by a reeling device.

8. The method for preparing the release film for leather according to claim 7, wherein the electron beam curing energy is 100KeV to 500 KeV.

9. The method for preparing the release film for leather according to claim 3, wherein the release agent is a photo-curing silicone release agent.

10. A release film for leather is characterized by comprising: the release film for leather is prepared by the preparation method of the release film for leather as claimed in any one of claims 1 to 9, and comprises a base material, a pre-coating layer and a release layer which are sequentially arranged.

Technical Field

The invention relates to the field of release film production, in particular to a release film for leather and a preparation method thereof.

Background

The traditional release paper for the artificial leather is limited by the physical strength of the base paper, the tearing problem is easy to occur due to the reduction of the strength after repeated use, the base paper can shrink in the high-temperature process to easily generate the curling problem, and the flatness of grains can be influenced due to the deformation of the base paper after repeated use.

At present, most release paper has complex hierarchical structures and complicated preparation methods, for example, chinese patent CN107722323A proposes a release film for UV-cured synthetic leather production, which is prepared by coating an embossing layer coating formed by mixing UV resin, a leveling agent and a photosensitizer on a PET film of 100-200 μm, and embossing and UV-irradiating the embossing layer coating at 85-95 ℃ in a semi-cured state to prepare a patterned release film, but the technology is subjected to limited energy density and irradiation of ultraviolet rays to limit the thickness of the ultraviolet-cured coating, so the ultraviolet-cured release film is only suitable for the pattern of a plane or a polar line, and the embossing layer coating is required to be in the semi-cured state in the manufacturing process, which is complicated in the manufacturing process.

Disclosure of Invention

In order to overcome the technical problems, the invention discloses a preparation method of a release film for leather; also discloses a release film for leather.

The technical scheme adopted by the invention for realizing the purpose is as follows:

a preparation method of a release film for leather comprises the following steps:

step 1, preparing a precoating paint;

step 2, preparing a release layer coating;

step 3, preparing a base material by using corona treatment;

step 4, coating the precoating coating on the base material, and curing to form a precoating layer to obtain a precoated base material;

and 5, embossing and curing the release layer coating on the pre-coated substrate to form a release layer by adopting a slit coating mode and assisting with an electron beam, so as to obtain the release film for the leather.

In the step 1, the pre-coating paint comprises the following components in parts by weight: 40-60 parts of deionized water, 20-40 parts of water-based acrylic emulsion and 1-10 parts of functional auxiliary agent.

In the step 2, the release layer coating is composed of the following components in parts by weight: 30-80 parts of aliphatic polyurethane propionic resin, 30-80 parts of modified epoxy acrylate, 10-80 parts of a monomer agent, 1-5 parts of a functional assistant, 1-5 parts of a release agent and 1-5 parts of a filler.

According to the preparation method of the release film for leather, the release layer coating further comprises 1-5 parts of antistatic particles by weight, and the antistatic particles are carbon nano tube particles, silver powder, nickel powder, copper powder, polythiophene compounds or quaternary phosphonium salt particles.

In the above method for preparing the release film for leather, in step 3, the corona treatment process parameters are as follows: the high-frequency alternating voltage is 5000-15000V/m²The production speed is 10-30 mpm.

The preparation method of the release film for leather comprises the following specific steps of the step 4: the precoating coating is applied to the substrate by a dimple or anilox roller and cured by heating at 120 ℃ for 90 seconds to form the precoating layer, thereby obtaining the precoated substrate.

The preparation method of the release film for leather comprises the following steps of: on electron beam curing equipment, the precoated substrate is guided to a coating device from an unreeling device, a slit coating mode is adopted to coat the release layer coating on the precoated layer to form the release layer, then the release layer is placed in the electron beam curing device, the release layer is subjected to embossing and curing by a pattern roller under electron beams to obtain the release film for leather, and the release film for leather is reeled by a reeling device.

The preparation method of the release film for leather comprises the step of curing the release film for leather by electron beams, wherein the electron beam curing energy is 100 KeV-500 KeV.

The preparation method of the release film for leather comprises the step of preparing a release agent, wherein the release agent is a photo-curing organic silicon release agent.

A release film for leather, comprising: the release film for leather is prepared by the preparation method, and comprises a base material, a pre-coating layer and a release layer which are sequentially arranged.

The invention has the beneficial effects that:

(1) the release film for leather comprises a three-layer structure, wherein the first layer is a release layer synthesized by aliphatic polyurethane propionic acid resin, the second layer is a precoating layer of water-based acrylic emulsion, the third layer is a PET (polyethylene terephthalate) base material which is subjected to corona treatment, and the embossing and the solidification of the release layer are simultaneously carried out by adopting a mode of assisting electron beam direct rolling to solidify and emboss, so that the problems of poor flatness and clear and vivid line of a product caused by the limitation of the physical strength of the base material of the traditional release film are solved, and the obtained product has the advantages of vivid line, solvent resistance, good surface scratch resistance, good flatness and high reuse rate;

(2) the release layer coating and the pre-coating adopted in the invention adopt the photo-curing material and the water-based coating, and no solvent is required to be added, thus having better environmental protection benefit;

(3) the formula and the proportion of the release layer coating and the pre-coating can be regulated and controlled according to different production requirements, so that the wear resistance, the solvent resistance, the peeling strength, the high temperature resistance and the line fidelity of the release paper are effectively coordinated and enhanced;

(4) the components in the pre-coating paint are coordinated with each other, so that the irregular structure of the surface of the base material is effectively eliminated, the roughness and the matching property of the surface of the base material are enhanced, and the adhesion and the bonding force between the release layer and the base material are further improved, so that the good characteristics of the release layer can be fully expressed;

(5) the pattern roller is used for embossing the pattern layer coating to form a film under the curing action of the electron beam, the grains on the pattern roller are directly transferred to the surface of the release film, and the simultaneous curing and embossing are realized, compared with the traditional ultraviolet curing technology, the manufactured grains are clear, the simulation degree can approach to 100% of the original grains of the pattern roller, the pattern roller has the advantages of high curing speed, high embossing precision, low energy consumption and no pollution, and the release layer has low surface energy, good adhesive force and peeling strength;

(6) the preparation method mainly adopts the reaction kettle and the electron beam curing equipment, has higher production efficiency, saves the production cost, has high production efficiency and is beneficial to large-scale production.

Detailed Description

The invention provides a preparation method of a release film for leather, which comprises the following steps:

step 1, preparing a precoating paint;

step 2, preparing a release layer coating;

step 3, preparing a base material by using corona treatment;

step 4, coating the precoating coating on the base material, and curing to form a precoating layer to obtain a precoated base material;

and 5, embossing and curing the release layer coating on the pre-coated substrate to form a release layer by adopting a slit coating mode and assisting with an electron beam, so as to obtain the release film for the leather.

It should be noted that the steps 1 to 3 do not have a strictly required preparation sequence, and the preparation sequence of the release layer material, the precoat material and the substrate can be set according to actual production requirements.

Preferably, in the step 1, the pre-coating paint consists of the following components in parts by weight: 40-60 parts of deionized water, 20-40 parts of water-based acrylic emulsion and 1-10 parts of functional auxiliary agent.

Preferably, the functional auxiliary agent is one or more of a silane coupling agent, a titanate coupling agent, a leveling agent, a surfactant and a defoaming agent; the functional auxiliary agent is used for adjusting the functions of surface tension, leveling property, defoaming property and the like of the pre-coating paint; the leveling agent, the surfactant, the defoaming agent and the like can effectively improve the coating surface effect of the precoating layer and reduce the problems of bubbles, poor leveling property and the like.

Preferably, in the step 2, the release layer coating consists of the following components in parts by weight: 30-80 parts of aliphatic polyurethane propionic resin, 30-80 parts of modified epoxy acrylate, 10-80 parts of a monomer agent, 1-5 parts of a functional assistant, 1-5 parts of a release agent and 1-5 parts of a filler.

Further, the release layer coating also comprises 1-5 parts of antistatic particles by weight, wherein the antistatic particles are carbon nano tube particles, silver powder, nickel powder, copper powder, polythiophene compounds or quaternary salt particles; the antistatic particles are convenient to adjust the antistatic performance of the release layer.

Preferably, the aliphatic polyurethane propionic acid resin is one or more of acrylic acid carbamate, alpha-hydrogen omega-hydroxyl (oxygen-1, 4-butanediyl), 1' -methylenebis (4-isocyanatocyclohexane), 2-propionic acid, 2-hydroxyethyl ester and 1, 6-hexanediol diacrylate; specifically, the aliphatic polyurethane propionic acid resin is used for controlling the functions of surface hardness, flexibility, solvent resistance, scratch resistance and the like of the release layer.

Preferably, the monomer is one or more of 1, 6-hexanediol diacrylate, tripropylene glycol diacrylate, cyclotrimethylolpropane formal acrylate, isodecyl alcohol acrylate, ethoxylated trimethylolpropane triacrylate, modified polyurethane acrylate and aliphatic diacrylate; specifically, the monomer agent is used for adjusting the viscosity of the release layer coating.

Preferably, the functional auxiliary agent is one or more of a silane coupling agent, a titanate coupling agent, a leveling agent, a surfactant and a defoaming agent; the functional auxiliary agent is used for adjusting the functions of surface tension, leveling property, defoaming property and the like of the release layer coating; the silane coupling agent and the titanate coupling agent can improve the coupling effect with the filler, so that the using amount of the filler is increased, the using amount of the aliphatic polyurethane propionic acid resin is reduced, and the production cost is reduced; the leveling agent, the surfactant, the defoaming agent and the like can effectively improve the coating surface effect of the release layer and reduce the problems of bubbles, poor leveling property and the like.

Preferably, the release agent is a photo-curing organic silicon release agent; the filler is one or more of light calcium carbonate, fumed silica, barium sulfate, calcined kaolin, talcum powder and titanium dioxide; specifically, the filler is used for reducing the manufacturing cost of the release layer coating and improving the functions of scratch resistance, whiteness and the like of the release layer.

Preferably, in step 3, a corona treatment is performed on a substrate raw material with a high-frequency alternating voltage to obtain a corona-treated substrate, the substrate raw material is a PET substrate, and the corona treatment process parameters are as follows: the high-frequency alternating voltage is 5000-15000V/m²The production speed is 10 ~ 30mpm, it is right that the substrate can improve its surface after corona treatment the adhesive force of precoating, and then improve the substrate is with the bonding performance from the type layer, and secondly, the physical strength and the roughness of PET membrane are high, can be used to produce the high type membrane product of repeated use rate, reduce the cost of artificial leather production.

Preferably, the specific steps of step 4 are: the precoating coating is applied to the substrate by a dimple or anilox roller and cured by heating at 120 ℃ for 90 seconds to form the precoating layer, thereby obtaining the precoated substrate.

Preferably, the step 5 specifically includes the following steps: guiding the precoated substrate from an unreeling device to a coating device on electron beam curing equipment, placing the release layer coating in a trough, coating the release layer coating on the precoated layer in a slit coating mode to form the release layer, then entering an electron beam curing device under the traction action of a guide roller, embossing and curing the release layer through a pattern roller under an electron beam to obtain the release film for the leather, and rolling the release film for the leather by a rolling device; specifically, the electron beam curing energy is 100 KeV-500 KeV, and the dose is 3-10 MR; the slit width of the slit coating was 10 μm, the coating amount of the release layer was measured by an X-ray detector, and an electron beam was irradiated from the back surface of the precoated substrate and passed through the precoated substrate to cure the release layer.

Specifically, the adopted micro-concave or anilox roller and pattern roller can be nickel embossing rollers or steel rollers formed by carving patterns through laser, and the lines of the steel rollers can be effectively and directly transferred onto the film surface of the pre-coating layer or the release layer in the curing process, so that the manufactured lines are clear and vivid, and the simulation degree is close to 100%.

Specifically, the coating weight of the precoat layer is 1-10 g/m²The coating weight of the release layer is 20-100 g/m²And the working speed of the electron beam curing equipment is 30-150 m/min.

The invention also discloses a release film for leather, which comprises: the release film for leather is prepared by the preparation method, and comprises a base material, a pre-coating layer and a release layer which are sequentially arranged.

Preferably, the precoating layer consists of the following components in parts by weight: 40-60 parts of deionized water, 20-40 parts of water-based acrylic emulsion and 1-10 parts of functional auxiliary agent.

Preferably, the functional auxiliary agent is one or more of a silane coupling agent, a titanate coupling agent, a leveling agent, a surfactant and a defoaming agent; the functional auxiliary agent is used for adjusting the functions of surface tension, leveling property, defoaming property and the like of the precoat layer; the leveling agent, the surfactant, the defoaming agent and the like can effectively improve the coating surface effect of the precoating layer and reduce the problems of bubbles, poor leveling property and the like.

Preferably, the release layer consists of the following components in parts by weight: 30-80 parts of aliphatic polyurethane propionic resin, 30-80 parts of modified epoxy acrylate, 10-80 parts of a monomer agent, 1-5 parts of a functional assistant, 1-5 parts of a release agent and 1-5 parts of a filler.

Further, the release layer further comprises 1-5 parts by weight of antistatic particles, wherein the antistatic particles are carbon nano tube particles, silver powder, nickel powder, copper powder, polythiophene compounds or quaternary salt particles; the antistatic particles are convenient to adjust the antistatic performance of the release layer.

Preferably, the aliphatic polyurethane propionic acid resin is one or more of acrylic acid carbamate, alpha-hydrogen omega-hydroxyl (oxygen-1, 4-butanediyl), 1' -methylenebis (4-isocyanatocyclohexane), 2-propionic acid, 2-hydroxyethyl ester and 1, 6-hexanediol diacrylate; specifically, the aliphatic polyurethane propionic acid resin is used for controlling the functions of surface hardness, flexibility, solvent resistance, scratch resistance and the like of the release layer.

Preferably, the monomer is one or more of 1, 6-hexanediol diacrylate, tripropylene glycol diacrylate, cyclotrimethylolpropane formal acrylate, isodecyl alcohol acrylate, ethoxylated trimethylolpropane triacrylate, modified polyurethane acrylate and aliphatic diacrylate; specifically, the monomer agent is used for adjusting the viscosity of the release layer.

Preferably, the functional auxiliary agent is one or more of a silane coupling agent, a titanate coupling agent, a leveling agent, a surfactant and a defoaming agent; the functional auxiliary agent is used for adjusting the functions of surface tension, leveling property, defoaming property and the like of the release layer; the silane coupling agent and the titanate coupling agent can improve the coupling effect with the filler, so that the using amount of the filler is increased, the using amount of the aliphatic polyurethane propionic acid resin is reduced, and the production cost is reduced; the leveling agent, the surfactant, the defoaming agent and the like can effectively improve the coating surface effect of the release layer and reduce the problems of bubbles, poor leveling property and the like.

Preferably, the release agent is a photo-curing organic silicon release agent; the filler is one or more of light calcium carbonate, fumed silica, barium sulfate, calcined kaolin, talcum powder and titanium dioxide; specifically, the filler is used for reducing the manufacturing cost of the release layer and improving the functions of scratch resistance, whiteness and the like of the release layer.

The present invention is further illustrated by the following specific examples, which are intended to facilitate the understanding and appreciation of the technical solutions of the present invention, rather than to limit the invention thereto.

Example 1: the embodiment provides a release film for leather and a preparation method thereof, and the preparation method comprises the following steps:

step 1, preparing a precoating coating: sequentially putting 45 parts of deionized water, 30 parts of aqueous acrylic emulsion, 2 parts of surfactant and 2 parts of defoaming agent into a container, and mixing and stirring to obtain uniform pre-coating paint;

step 2, preparing release layer coating: according to the weight parts, 30 parts of acrylic carbamate, 70 parts of modified epoxy acrylate, 10 parts of tripropylene glycol diacrylate, 10 parts of ethoxylated trimethylolpropane triacrylate, 2 parts of perfluoro methacrylate, 2 parts of gamma-methacryloxypropyl trimethylsilane, 1 part of photo-curing organosilicon release agent and 5 parts of light calcium carbonate are sequentially put into a container to be mixed and stirred so as to promote solid components to be fully dissolved, so that the uniform release layer coating is obtained, and a vacuum pump is adopted to pump out air bubbles and dark bubbles in the release layer coating so as to avoid the problems of fisheyes, pinholes and the like on the release layer in the subsequent curing process;

step 3, preparing a base material by corona treatment: carrying out high-frequency alternating-current voltage corona treatment on a PET (polyethylene terephthalate) base material to obtain a corona base material; wherein the high frequency AC voltage is 10000V/m²The production speed is 20 mpm;

step 4, coating 10g of the pre-coating paint on 200g of the base material, and forming a pre-coating layer after curing for 90s at 100 ℃ to obtain a pre-coated base material; wherein the coating weight of the precoat layer is 10g/m²；

Step 5, guiding the precoated substrate from an unreeling device to a coating device on an electron beam curing device, placing the release layer coating in a trough, coating 100g of the release layer coating on the precoated layer in a slit coating mode to form a release layer, then entering an electron beam curing device under the traction action of a guide roller, embossing by a pattern roller with the assistance of an electron beam with 300KeV energy and 5MR dosage under the condition that the working speed is 150m/min, curing the release layer by the electron beam to obtain the release film for the leather, and reeling the release film for the leather by a reeling device; wherein the coating amount of the release layer is measured by an X-ray detector, the slit width of the slit coating is 10 μm, and the coating amount of the release layer is 40g/m²。

Example 2: the embodiment provides a release film for leather and a preparation method thereof, and the preparation method comprises the following steps:

step 1, preparing a precoating coating: sequentially putting 50 parts of deionized water, 35 parts of aqueous acrylic emulsion, 2 parts of surfactant and 2 parts of defoaming agent into a container, and mixing and stirring to obtain uniform pre-coating paint;

step 2, preparing release layer coating: according to the weight parts, 50 parts of acrylic carbamate, 50 parts of modified epoxy acrylate, 10 parts of tripropylene glycol diacrylate, 10 parts of ethoxylated trimethylolpropane triacrylate, 2 parts of perfluoro methacrylate, 2 parts of gamma-methacryloxypropyl trimethylsilane, 3 parts of photocuring organic silicon release agent and 5 parts of light calcium carbonate are sequentially placed into a container to be mixed and stirred so as to promote solid components to be fully dissolved, and uniform release layer coating is obtained, and a vacuum pump is adopted to pump out air bubbles and dark bubbles in the release layer coating so as to avoid the problems of fisheyes, pinholes and the like on the release layer in the subsequent curing process;

step 3, preparing a base material by corona treatment: carrying out high-frequency alternating-current voltage corona treatment on a PET (polyethylene terephthalate) base material to obtain a corona base material; wherein the high frequency AC voltage is 12000V/m²The production speed is 20 mpm;

step 4, coating 10g of the pre-coating paint on 200g of the base material, and forming a pre-coating layer after curing for 90s at 100 ℃ to obtain a pre-coated base material; wherein the coating weight of the precoat layer is 10g/m²；

Step 5, guiding the precoated substrate from an unreeling device to a coating device on an electron beam curing device, placing the release layer coating in a trough, coating 100g of the release layer coating on the precoated layer in a slit coating mode to form a release layer, then entering an electron beam curing device under the traction action of a guide roller, embossing by a pattern roller with the assistance of an electron beam with 300KeV energy and 5MR dosage under the condition that the working speed is 150m/min, curing the release layer by the electron beam to obtain the release film for the leather, and reeling the release film for the leather by a reeling device; wherein the coating amount of the release layer is measured by an X-ray detector, the slit width of the slit coating is 10 μm, and the coating amount of the release layer is 40g/m²。

Example 3: the embodiment provides a release film for leather and a preparation method thereof, and the preparation method comprises the following steps:

step 1, preparing a precoating coating: sequentially putting 50 parts of deionized water, 35 parts of aqueous acrylic emulsion, 2 parts of surfactant and 2 parts of defoaming agent into a container, and mixing and stirring to obtain uniform pre-coating paint;

step 2, preparing release layer coating: according to the weight parts, 70 parts of alpha-hydrogen omega-hydroxyl (oxygen-1, 4-butanediyl), 30 parts of modified epoxy acrylate, 10 parts of 1, 6-hexanediol diacrylate, 10 parts of ethoxylated trimethylolpropane triacrylate, 2 parts of perfluoro methacrylate, 2 parts of gamma-methacryloxypropyltrimethylsilane, 3 parts of a photocuring organic silicon release agent and 5 parts of light calcium carbonate are sequentially placed into a container to be mixed and stirred so as to promote the solid components to be fully dissolved, so that the uniform release layer coating is obtained, and air bubbles and dark bubbles in the release layer coating are pumped out by a vacuum pump so as to avoid the problems of fish eyes, pinholes and the like on the release layer in the subsequent curing process;

step 3, preparing a base material by corona treatment: carrying out high-frequency alternating-current voltage corona treatment on a PET (polyethylene terephthalate) base material to obtain a corona base material; wherein the high frequency AC voltage is 12000V/m²The production speed is 20 mpm;

step 4, coating 10g of the pre-coating paint on 200g of the base material, and forming a pre-coating layer after curing for 90s at 100 ℃ to obtain a pre-coated base material; wherein the coating weight of the precoat layer is 10g/m²；

Step 5, guiding the precoated substrate from an unreeling device to a coating device on an electron beam curing device, placing the release layer coating in a trough, coating 100g of the release layer coating on the precoated layer in a slit coating mode to form a release layer, then entering an electron beam curing device under the traction action of a guide roller, embossing by a pattern roller with the assistance of an electron beam with 300KeV energy and 5MR dosage under the condition that the working speed is 150m/min, curing the release layer by the electron beam to obtain the release film for the leather, and reeling the release film for the leather by a reeling device; wherein the coating amount of the release layer is measured by an X-ray detector, and the slit coating is narrowThe width of the seam is 10 mu m, and the coating weight of the release layer is 40g/m²。

Example 4: the embodiment provides a release film for leather and a preparation method thereof, and the preparation method comprises the following steps:

step 1, preparing a precoating coating: sequentially putting 50 parts of deionized water, 35 parts of aqueous acrylic emulsion, 2 parts of surfactant and 2 parts of defoaming agent into a container, and mixing and stirring to obtain uniform pre-coating paint;

step 2, preparing release layer coating: according to the weight parts, 70 parts of alpha-hydrogen omega-hydroxyl (oxygen-1, 4-butanediyl), 30 parts of modified epoxy acrylate, 10 parts of 1, 6-hexanediol diacrylate, 10 parts of ethoxylated trimethylolpropane triacrylate, 2 parts of perfluoro methacrylate, 2 parts of gamma-methacryloxypropyltrimethylsilane, 3 parts of carbon nanotube particles, 1 part of nickel powder, 3 parts of light-cured organic silicon release agent and 5 parts of light calcium carbonate are sequentially placed in a container to be mixed and stirred so as to promote the solid components to be fully dissolved, so that the uniform release layer coating is obtained, and a vacuum pump is adopted to pump out air bubbles and dark bubbles in the release layer coating so as to avoid the problems of fish eyes, pinholes and the like on the release layer in the subsequent curing process;

step 3, preparing a base material by corona treatment: carrying out high-frequency alternating-current voltage corona treatment on a PET (polyethylene terephthalate) base material to obtain a corona base material; wherein the high frequency AC voltage is 12000V/m²The production speed is 20 mpm;

step 4, coating 10g of the pre-coating paint on 200g of the base material, and forming a pre-coating layer after curing for 90s at 100 ℃ to obtain a pre-coated base material; wherein the coating weight of the precoat layer is 10g/m²；

Step 5, guiding the precoated base material from an unreeling device to a coating device on an electron beam curing device, coating 100g of release layer coating on the precoated layer in a slit coating mode to form the release layer, then enabling the release layer to enter the electron beam curing device, conducting embossing on the release layer through a pattern roller under the condition that the working speed is 150m/min by assisting with electron beams with 300KeV energy and 5MR dosage, and curing the release layer by electron beams to obtain the release layerThe release film for the leather is wound by a winding device; wherein the slit width of the slit coating is 10 μm, and the coating amount of the release layer is 40g/m²。

The release films for leather prepared in examples 1 to 4 were subjected to the following performance tests:

1. temperature resistance and solvent resistance:

respectively preparing the release films for leather prepared in the embodiments 1 to 4 into small samples with the specification of 100mm x 100mm under the same condition, dripping 10N, N-Dimethylformamide (DMF) of 0.2mL at different positions on the surface of the release film for leather, putting the release film for leather into a thermostat with the temperature of 105 ℃ for 5 minutes, putting a sample into the thermostat with the temperature of 150 ℃ for 3 minutes, taking out the release film and observing the number of coating explosion at the position where the N, N-dimethylformamide is dripped; and if the coating is not blasted, the coating is regarded as qualified.

2. The repeated use times are as follows:

coating PU slurry with the thickness of 150 mu m on the surface of the release film for leather, drying at 150 ℃ for 3 minutes to form a film, scraping glue and base cloth on the PU film, putting the PU film into an oven for drying, peeling the base cloth, cleaning the film surface of the release film for leather, repeating the operations until the release film falls off or cannot be peeled, and recording the maximum repeated use times.

3. Tape peel force:

with standard pressure sensitive adhesive tapes 25mm wide, for example: tesa 7475, 7476, 4651, 4154 and Takstrip, etc., or a face material coated with a standard pressure sensitive adhesive, cutting a 25mm by 100mm sample of leather from a release film, placing the sample on a glass plate, placing a flat metal plate on the sample, the metal plate and the above accessories uniformly providing 70g/cm²At a temperature of 23 ℃ (± 2 ℃) for 20 hours and at standard test conditions of 23 ± 2 ℃ and 50 ± 5% RH for not less than 4 hours.

During detection, the peel strength of the sample is measured when the peel strength meter peels the release film from the leather film at an angle of 180 degrees and a speed of 300 mm/min. Parallel 5 times, average, unit: n/25 mm.

4. Residual situation

Coating PU slurry with the thickness of 150 mu m on the surface of a release film, drying at 150 ℃ for 3 minutes to form a film, then scraping glue and base fabric on the PU film, putting the PU film into an oven for drying, and peeling off the leather film. The film surface was observed for PU residue.

Through determination, the performance test results of the release films for leather prepared in examples 1 to 4 are as follows:

table 1 results of performance testing

As can be seen from the performance test results, the release film for leather prepared by the preparation method provided by the invention has the characteristics of good high temperature resistance, solvent resistance, release performance, peeling property, residue resistance and the like.

The invention has the following advantages:

(1) the release film for leather comprises a three-layer structure, wherein the first layer is a release layer synthesized by aliphatic polyurethane propionic acid resin, the second layer is a precoating layer of water-based acrylic emulsion, the third layer is a PET (polyethylene terephthalate) base material which is subjected to corona treatment, and the embossing and the solidification of the release layer are simultaneously carried out by adopting a mode of assisting electron beam direct rolling to solidify and emboss, so that the problems of poor flatness and clear and vivid line of a product caused by the limitation of the physical strength of the base material of the traditional release film are solved, and the obtained product has the advantages of vivid line, solvent resistance, good surface scratch resistance, good flatness and high reuse rate;

(2) the release layer coating and the pre-coating adopted in the invention adopt the photo-curing material and the water-based coating, and no solvent is required to be added, thus having better environmental protection benefit;

(3) the formula and the proportion of the release layer coating and the pre-coating can be regulated and controlled according to different production requirements, so that the wear resistance, the solvent resistance, the peeling strength, the high temperature resistance and the line fidelity of the release paper are effectively coordinated and enhanced;

(4) the components in the pre-coating paint are coordinated with each other, so that the irregular structure of the surface of the base material is effectively eliminated, the roughness and the matching property of the surface of the base material are enhanced, and the adhesion and the bonding force between the release layer and the base material are further improved, so that the good characteristics of the release layer can be fully expressed;

(5) the pattern roller is used for embossing the pattern layer coating to form a film under the curing action of the electron beam, the grains on the pattern roller are directly transferred to the surface of the release film, and the simultaneous curing and embossing are realized, compared with the traditional ultraviolet curing technology, the manufactured grains are clear, the simulation degree can approach to 100% of the original grains of the pattern roller, the pattern roller has the advantages of high curing speed, high embossing precision, low energy consumption and no pollution, and the release layer has low surface energy, good adhesive force and peeling strength;

(6) the preparation method mainly adopts the reaction kettle and the electron beam curing equipment, has higher production efficiency, saves the production cost, has high production efficiency and is beneficial to large-scale production.

The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. Those skilled in the art can make many possible variations and modifications to the invention using the above disclosed technical means and teachings, or can modify equivalent embodiments with equivalent variations, without departing from the scope of the invention. Therefore, all equivalent changes made according to the shape, structure and principle of the present invention should be covered by the protection scope of the present invention without departing from the contents of the technical scheme of the present invention.