Preparation method of high-durability release film

Abstract

According to the preparation method of the high-durability release film provided by the invention, a coating system with a three-layer structure is constructed, so that the scratch resistance and the release stability of a film material are remarkably improved. The method comprises the following steps: carrying out a reaction on aminopropyltriethoxysilane, methyltrimethoxysilane and ethyl acetate to prepare a pre-modified silane solution, and adding an ultraviolet light initiator, a fluorine-containing polyether surface conditioning agent and epoxy-terminated polydimethylsiloxane to prepare the release coating liquid. The coating liquid is divided into three parts, the ratio of the cross-linking accelerant to the fluorine-containing regulator is adjusted respectively, a bottom layer coating liquid, a middle layer coating liquid and a surface layer coating liquid are prepared and sequentially coated on a PET film subjected to plasma treatment, and each layer is subjected to drying and ultraviolet curing treatment. And the surface layer adopts a segmented ultraviolet radiation mode to induce fluorine-containing components to be separated and enriched to the surface so as to form a functional layer with a periodic micro-nano structure. Finally, the film material is subjected to hot pressing and annealing treatment, and the high-durability release film with mechanical stability and excellent desorption performance is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of release films, and particularly to a preparation method of a high-durability release film. Background Art

[0002] In the prior art, release films are widely used in fields such as electronic devices, optical protective films, die-cutting materials, and new energy battery encapsulation. They mainly form a functional coating by coating an organosilicon release agent on the surface of a polyester-based substrate, thereby endowing it with certain peeling properties and surface lubricity. Common preparation methods for release films mostly adopt single-layer or double-layer coating structures, and initially regulate the release force, thermal stability, and interfacial adhesion properties by adjusting the type of silicone oil, crosslinking density, and additive amount of auxiliaries.

[0003] However, in the case of long-term high temperature and high humidity, repeated peeling, or high-intensity die-cutting applications of the above-mentioned conventional release films, problems such as surface scratches, large fluctuations in release force, and uncontrollable microstructure are likely to occur, resulting in shortened product life and decreased process yield. Especially in high-end electronic packaging and precision die-cutting scenarios, the release film has higher requirements for the stability of the peeling force, surface scratch resistance, and structural integrity, and it is difficult for traditional preparation methods to balance multiple performance indicators.

[0004] In view of this, there is an urgent need for a preparation method of a high-durability release film with a controllable structure, stable performance, and suitable for multiple harsh working conditions. Summary of the Invention

[0005] The present application provides a preparation method of a high-durability release film to improve the scratch resistance of the film material.

[0006] The present application provides a preparation method of a high-durability release film, including the following steps:

[0007] (1) Put 55 parts by mass of aminopropyltriethoxysilane, 190 parts of ethyl acetate, and 8 parts of methyltrimethoxysilane into a reaction vessel, and stir and react at 65 °C for 3 hours to obtain a pre-modified silane solution;

[0008] (2) Based on the mass of the pre-modified silane solution, add 0.5% of the ultraviolet light initiator 2-hydroxy-2-methyl-1-phenylpropanone, 1.0% of a fluorinated polyether-based surface modifier with a terminal perfluoroalkyl structure, and 1.5% of an epoxy-terminated polydimethylsiloxane to the pre-modified silane solution, and stir evenly at room temperature to obtain a release coating solution;

[0009] (3) Divide the release coating solution prepared in step (2) into three equal parts, and respectively formulate and add a crosslinking promoter and a fluorinated polyether-based surface modifier to sequentially obtain a bottom coating solution, an intermediate coating solution, and a surface coating solution, specifically including:

[0010] Based on the mass of the first release coating solution, 2.0% of dicumyl peroxide as a crosslinking accelerator and 0.5% of a fluorinated polyether-based surface modifier were added to the first release coating solution to obtain the bottom coating solution;

[0011] Based on the mass of the second release coating solution, 1.0% of dicumyl peroxide as a crosslinking accelerator and 0.5% of a fluorinated polyether-based surface modifier were added to the second release coating solution to obtain the intermediate layer coating solution;

[0012] Based on the mass of the third release coating solution, no dicumyl peroxide as a crosslinking accelerator was added, and only 2.0% of a fluorinated polyether-based surface modifier was added to the third release coating solution to obtain the surface coating solution;

[0013] (4) A PET film substrate treated with oxygen plasma was provided, and the bottom coating solution, the intermediate layer coating solution, and the surface coating solution were sequentially coated on the PET film substrate by gravure coating, specifically including:

[0014] The bottom coating solution was coated on the PET film substrate with a wet film thickness of 7 μm, dried with hot air at 100 °C for 2 minutes after coating, and ultraviolet light irradiation curing was performed using a high-pressure mercury lamp with a wavelength of 365 nm and a power density of 120 mW / cm 2 The irradiation energy density was 150 mJ / cm 2 ;

[0015] The intermediate layer coating solution was coated on the cured bottom layer with a wet film thickness of 7 μm, dried for 2 minutes, and ultraviolet light irradiation curing was performed using a high-pressure mercury lamp with a wavelength of 365 nm and a power density of 120 mW / cm 2 The irradiation energy density was 150 mJ / cm 2 ;

[0016] The surface coating solution was coated on the cured intermediate layer with a wet film thickness of 7 μm, dried for 2 minutes, and then ultraviolet light irradiation curing was performed using a high-pressure mercury lamp with a wavelength of 365 nm and a power density of 120 mW / cm 2 The irradiation process was carried out in three times, the energy density of each irradiation was 60 mJ / cm 2 There was an interval of 10 seconds between two irradiations, and the total irradiation energy density was 180 mJ / cm 2 to control the curing rate of the surface layer, promote the phase separation and migration of the fluorine-containing components during the curing process to the surface, and thus form a periodic micro-nano protrusion structure on the surface;

[0017] (5) The three-layer coated film after UV curing is placed under hot pressing treatment at 130 °C for 3 minutes with a pressure of 12 MPa, and then transferred to a hot air circulation oven at 150 °C for annealing for 10 hours, and cooled to room temperature to obtain a high-durability release film.

[0018] In the present invention, by controlling the rate and energy input process of UV curing, an environment conducive to the migration and phase separation of fluorinated polyether chain segments is formed on the surface layer. Specifically, three spaced UV irradiations (60 mJ / cm each time 2 , with an interval of 10 seconds and a total energy of 180 mJ / cm 2 ) are used instead of single continuous irradiation, which slows down the crosslinking rate and helps the highly migratory fluorinated chain segments to first aggregate at the interface and then be stably fixed during slow crosslinking. This process not only makes the surface layer chemically inhomogeneous but also causes physical surface tension differences, thereby naturally inducing the periodic arrangement of micro-nano-scale raised structures.

[0019] The measured average period of the surface microstructure is 600 ± 50 nm, and the depth is 100 ± 20 nm, effectively improving the surface scratch resistance of the film material and reducing the contact area, which is beneficial to the stability of the release process.

[0020] Compared with the prior art, the technical effects of the present invention are significant and multi-faceted. Using a unified coating liquid basic system, a three-layer functional coating structure is realized only through ratio adjustment, with a simple formula, an orderly structure, and good process compatibility; in the three-layer structure, the crosslinking degree decreases layer by layer, while the fluorine-containing component increases layer by layer, ensuring the internal structural strength while guaranteeing the surface lubrication and desorption ability; the surface layer induces the formation of micro-nano structures through segmented UV irradiation, effectively improving the scratch resistance and reducing the wear coefficient, endowing the release film with performance stability under multiple peelings; after film formation, hot pressing + annealing treatment further enhances the structural denseness, reduces internal stress, and improves the long-term service reliability of the film material. Specific Embodiments

[0021] Many specific details are set forth in the following description in order to provide a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0022] The first embodiment of the present invention provides a method for preparing a high-durability release film, including the following steps:

[0023] (1) 55 parts by mass of aminopropyltriethoxysilane, 190 parts of ethyl acetate, and 8 parts of methyltrimethoxysilane are placed in a reaction vessel and stirred and reacted at 65 °C for 3 hours to obtain a pre-modified silane solution;

[0024] (2) Based on the mass of the pre-modified silane solution, add 0.5% of the ultraviolet light initiator 2-hydroxy-2-methyl-1-phenylpropanone, 1.0% of the fluorinated polyether-based surface modifier with a terminal perfluoroalkyl structure, and 1.5% of the epoxy-terminated polydimethylsiloxane to the pre-modified silane solution, and stir evenly at room temperature to obtain a release coating solution;

[0025] (3) Divide the release coating solution prepared in step (2) into three equal parts, and respectively formulate and add a crosslinking promoter and a fluorinated polyether-based surface modifier to sequentially prepare a bottom coating solution, an intermediate layer coating solution, and a surface layer coating solution, specifically including:

[0026] Based on the mass of the first portion of the release coating solution, add 2.0% of the crosslinking promoter dicumyl peroxide to the first portion of the release coating solution, and add 0.5% of the fluorinated polyether-based surface modifier to prepare a bottom coating solution;

[0027] Based on the mass of the second portion of the release coating solution, add 1.0% of the crosslinking promoter dicumyl peroxide to the second portion of the release coating solution, and add 0.5% of the fluorinated polyether-based surface modifier to prepare an intermediate layer coating solution;

[0028] Based on the mass of the third portion of the release coating solution, do not add the crosslinking promoter dicumyl peroxide to the third portion of the release coating solution, and only add 2.0% of the fluorinated polyether-based surface modifier to prepare a surface layer coating solution;

[0029] (4) Provide a PET film substrate treated with oxygen plasma, and use the gravure coating method to sequentially coat the bottom coating solution, the intermediate layer coating solution, and the surface layer coating solution on the PET film substrate, specifically including:

[0030] Coat the bottom coating solution on the PET film substrate, with a wet film thickness of 7 μm, dry in hot air at 100 °C for 2 minutes after coating, and use a high-pressure mercury lamp with a wavelength of 365 nm and a power density of 120 mW / cm 2 for ultraviolet light irradiation curing, with an irradiation energy density of 150 mJ / cm 2 ;

[0031] Coat the intermediate layer coating solution on the already cured bottom layer, with a wet film thickness of 7 μm, dry for 2 minutes, and use a high-pressure mercury lamp with a wavelength of 365 nm and a power density of 120 mW / cm 2 for ultraviolet light irradiation curing, with an irradiation energy density of 150 mJ / cm 2 ;

[0032] Coat the surface layer coating solution on the already cured intermediate layer, with a wet film thickness of 7 μm, dry for 2 minutes, and then use a high-pressure mercury lamp with a wavelength of 365 nm and a power density of 120 mW / cm 2The UV light curing is carried out by using a high-pressure mercury lamp. The irradiation process is divided into three times, and the energy density of each irradiation is 60 mJ / cm 2 , with a 10-second interval between two irradiations, and the total irradiation energy density is 180 mJ / cm 2 , so as to control the curing rate of the surface layer, promote the phase separation of the fluorine-containing component during the curing process and migrate to the surface, thereby forming a periodic micro-nano convex structure on the surface;

[0033] (5) The UV-cured three-layer coating film is placed under the condition of 130 °C for hot pressing treatment for 3 minutes, and the pressure is 12 MPa. Then it is transferred to a hot air circulation oven at 150 °C for annealing for 10 hours, and cooled to room temperature to obtain a high-durability release film.

[0034] The specific implementation method is as follows:

[0035] In a 500-ml three-necked flask, 55 parts of aminopropyltriethoxysilane, 190 parts of ethyl acetate and 8 parts of methyltrimethoxysilane are added. After stirring and mixing evenly, it is heated at 65 °C and continuously stirred and reacted for 3 hours to obtain a transparent and homogeneous pre-modified silane solution. In this solution, the amino functional group and the methylsiloxane part undergo condensation to form a basic organic silicon network solution with preliminary reaction activity.

[0036] At room temperature, based on the mass of the above pre-modified silane solution, 0.5% of the UV initiator 2-hydroxy-2-methyl-1-phenylpropanone (Irgacure 1173, manufacturer is BASF), 1.0% of a fluorinated polyether surface modifier with a terminal perfluoroalkyl structure (English name is Fluorolink E10-H, Chinese name is polyperfluoroethoxymethoxydifluoroethyl PEG ether, manufacturer is Guangdong Wengjiang Chemical Reagent Co., Ltd.) and 1.5% of epoxy-terminated polydimethylsiloxane (the epoxypropoxylpropyl-terminated polydimethylsiloxane provided by Hubei Maidehao Biotechnology Co., Ltd. can be selected, model is MDH) are added. The mixed system is stirred evenly at room temperature for 45 minutes to obtain a clear, transparent and non-layered release coating liquid.

[0037] The obtained release coating solution was evenly divided into three portions, which were used to prepare the bottom coating solution, the intermediate coating solution, and the top coating solution with different functions respectively. In the first portion of the liquid, based on its mass, 2.0% of the crosslinking promoter dicumyl peroxide was added, and at the same time, the total dosage of the fluorinated surface regulator (English name: Fluorolink E10-H, Chinese name: polyperfluoroethoxy methoxy difluoroethyl PEG ether, manufacturer: Guangdong Wengjiang Chemical Reagent Co., Ltd.) was adjusted to 0.5% as the bottom coating solution. Similarly, in the second portion, 1.0% of dicumyl peroxide was added, and the fluorinated regulator was still 0.5% as the intermediate coating solution. In the third portion, no crosslinking promoter was added, but the fluorinated surface regulator (English name: Fluorolink E10-H, Chinese name: polyperfluoroethoxy methoxy difluoroethyl PEG ether, manufacturer: Guangdong Wengjiang Chemical Reagent Co., Ltd.) was added to 2.0% as the top coating solution.

[0038] A PET film with a thickness of 50 microns and a surface tension of about 42 mN / m was selected as the substrate, and oxygen plasma treatment (treatment power 60 watts, time 10 seconds) was carried out to enhance the coating adhesion. Subsequently, the three-layer structure was coated in sequence by the gravure coating method. The coating process is as follows: The bottom coating solution was uniformly applied to the substrate at a standard wet film thickness of 7 microns, dried by hot air at 100 °C for 2 minutes, and then ultraviolet irradiation curing was carried out using a high-pressure mercury lamp with a wavelength of 365 nm and a power density of 120 W / cm, and the irradiation energy density was 150 mJ / cm 2 . Then, the intermediate coating solution was coated on the cured bottom layer, with the same thickness of 7 microns, and the drying and ultraviolet curing conditions were the same. Finally, the top coating solution was coated on the intermediate layer, with a wet film thickness of 7 microns. After drying for 2 minutes, a segmented ultraviolet light irradiation curing was carried out using a high-pressure mercury lamp with a wavelength of 365 nm and a power density of 120 mW / cm 2 . This process was divided into three irradiations in total, and the energy density of each irradiation was 60 mJ / cm 2 , and the interval between two irradiations was 10 seconds, and the total energy density was accumulated to 180 mJ / cm 2 . Through this step-by-step irradiation method, the ultraviolet crosslinking rate of the top layer was effectively controlled, so that the fluorinated chain segments with strong migration ability in the system gradually enriched on the coating surface before complete curing and were locked by the network structure during the final stage of curing, thereby inducing the formation of a periodically arranged micro-nano protrusion structure. Actual tests showed that the average period of this structure was about 600 nanometers, and the average height was 100 ± 20 nanometers.

[0039] After the three-layer coating was completed and cured, the obtained film material was placed under a thermal pressing treatment at 130 °C, with a pressure of 12 MPa applied and maintained for 3 minutes, and then transferred to a hot air circulation oven at 150 °C for annealing for 10 hours to release internal stress. Finally, it was naturally cooled to room temperature to obtain a three-layer structured high-durability release film with a thickness of about 20 microns.

[0040] To verify the performance of the prepared film material, comprehensive tests including initial peel strength, peel strength retention rate at high temperature and high humidity, surface friction coefficient, scratch resistance, and microstructural morphology were carried out on it. The test results are as follows:

[0041] The initial peel strength of the prepared film was 15.6 g / in. After 5000 peelings under the conditions of 85 °C and 85% relative humidity, the peel strength retention rate still reached 91.2%. The surface friction coefficient measured by the steel ball sliding method was 0.19, which was significantly lower than 0.34 of the ordinary single-layer silicone oil release film. The scratch depth measured by a nano-scratch tester under a load of 10 mN was only 85 nm, showing obvious improvement compared with the 235 nm depth of the commercially available ordinary film. Using an atomic force microscope to observe the surface morphology, regularly distributed micro-nano protrusions could be seen, with good periodicity and uniformity, while there was no obvious structure on the surface of the comparative sample.

[0042] The experimental results show that the three-layer distributed release coating structure provided by the present invention, through the layer-by-layer regulation of the crosslinking degree and the concentration of fluorinated chain segments, while ensuring the overall structural strength, realizes the control of the surface energy and the adjustment of the microconfiguration of the surface layer, significantly improving the durability and stability of the film material under multiple uses and in hot and humid environments, and having excellent industrial application prospects.

[0043] Although this application is disclosed above with preferred embodiments, it is not used to limit this application. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of this application. Therefore, the protection scope of this application should be subject to the scope defined by the claims of this application.

Claims

1. A method for preparing a high-durability release film, characterized in that, It includes the following steps: (1) Put 55 parts by mass of aminopropyltriethoxysilane, 190 parts of ethyl acetate and 8 parts of methyltrimethoxysilane into a reaction vessel, and stir and react at 65 °C for 3 hours to obtain a pre-modified silane solution; (2) Based on the mass of the pre-modified silane solution, add 0.5% of the ultraviolet initiator 2-hydroxy-2-methyl-1-phenylpropanone, 1.0% of a fluorinated polyether surface modifier with a terminal perfluoroalkyl structure, and 1.5% of epoxy-terminated polydimethylsiloxane to the pre-modified silane solution, and stir evenly at room temperature to obtain a release coating solution; (3) Divide the release coating solution prepared in step (2) into three equal parts, and respectively formulate and add a crosslinking promoter and a fluorinated polyether surface modifier to sequentially obtain a bottom coating solution, an intermediate coating solution and a surface coating solution, specifically including: Based on the mass of the first portion of the release coating solution, add 2.0% of the crosslinking promoter dicumyl peroxide and 0.5% of the fluorinated polyether surface modifier to the first portion of the release coating solution to obtain a bottom coating solution; Based on the mass of the second portion of the release coating solution, add 1.0% of the crosslinking promoter dicumyl peroxide and 0.5% of the fluorinated polyether surface modifier to the second portion of the release coating solution to obtain an intermediate coating solution; Based on the mass of the third portion of the release coating solution, do not add the crosslinking promoter dicumyl peroxide, and only add 2.0% of the fluorinated polyether surface modifier to the third portion of the release coating solution to obtain a surface coating solution; (4) Provide a PET film substrate treated with oxygen plasma, and use the gravure coating method to sequentially coat the bottom coating solution, the intermediate coating solution and the surface coating solution on the PET film substrate, specifically including: Coat the bottom coating solution on the PET film substrate with a wet film thickness of 7 μm. After coating, dry it with hot air at 100 °C for 2 minutes, and use a high-pressure mercury lamp with a wavelength of 365 nm and a power density of 120 mW / cm 2 for ultraviolet light irradiation curing. The irradiation energy density is 150 mJ / cm 2 ; Apply the intermediate layer coating solution on the cured bottom layer, with a wet film thickness of 7 μm. After drying for 2 minutes, use a high-pressure mercury lamp with a wavelength of 365 nm and a power density of 120 mW / cm 2 for UV curing by irradiation, with an irradiation energy density of 150 mJ / cm 2 ; Apply the surface coating solution on the cured intermediate layer, with a wet film thickness of 7 μm. After drying for 2 minutes, use a high-pressure mercury lamp with a wavelength of 365 nm and a power density of 120 mW / cm 2 for ultraviolet light irradiation curing. The irradiation process is carried out in three times, and the energy density of each irradiation is 60 mJ / cm 2 , with an interval of 10 seconds between two irradiations. The total irradiation energy density is 180 mJ / cm 2 , to control the curing rate of the surface layer, promote the phase separation and migration of the fluorine-containing component to the surface during the curing process, so as to form a periodic micro-nano protrusion structure on the surface; (5) Place the three-layer coated film after ultraviolet curing under the conditions of 130 °C for hot pressing treatment for 3 minutes, with a pressure of 12 MPa, then transfer it to a hot air circulation oven at 150 °C for annealing for 10 hours, and cool to room temperature to obtain a high-durability release film.