A solvent-free high-temperature-resistant silicone release film and a preparation method thereof

Abstract

The application relates to the technical field of coating materials, and particularly discloses a solvent-free high-temperature-resistant organic silicon release film and a preparation method thereof. The solvent-free high-temperature-resistant organic silicon release film is prepared from the following raw materials: end-vinyl silicone oil, hyperbranched polysiloxane, multifunctional vinyl silane oligomer, crosslinking agent, platinum gold catalyst, alkyne alcohol type retarder, epoxy silane coupling agent and MQ silicone resin; and the preparation method comprises the following steps: S1, mixing and stirring part of the raw materials; S2, adding the epoxy silane coupling agent and the alkyne alcohol type retarder into the base polymer blend and stirring uniformly; S3, adding the hydrogen-containing silicone oil crosslinking agent into the modified inhibition mixture; S4, adding the platinum gold catalyst into the crosslinking agent dispersion system; and S5, coating the solvent-free release agent composition on the surface of a base material. The release film can be used for flexible circuit board high-temperature processing protection and high-temperature pressure-sensitive adhesive tape release layers for electronic component processing, and has the advantages of high heat resistance, good dimensional stability, strong adhesion to the base material and solvent-free environmental protection.

Description

Technical Field

[0001] This application relates to the field of coating materials technology, and more specifically, to a solvent-free, high-temperature resistant silicone release film and its preparation method. Background Technology

[0002] The application of coating materials in the field of release films mainly achieves controllable release force by regulating surface energy. Its advantage lies in the ability to customize silicone, fluoropolymer or non-silicone coating systems according to different substrates and end-user requirements. These coatings not only provide stable peel performance, but also endow the film with excellent temperature resistance, chemical stability and residual adhesion. At the same time, the coating process ensures the ultra-thin uniformity and defect-free surface of the coating, thus outperforming uncoated or traditionally treated films in terms of improving die-cutting efficiency, protecting the integrity of the adhesive surface and meeting special industrial standards such as silicone-free transfer.

[0003] Related coating materials use silicone or fluorine-containing coatings to regulate the surface energy of the release film to achieve controllable peeling. However, when faced with stringent industrial requirements such as high-frequency miniaturized die-cutting and silicone-free transfer, these traditional systems often struggle to achieve a balance between high-temperature dimensional stability, substrate adhesion strength, and precise adjustment of release force. Insufficient crosslinking density of linear silicone can easily lead to network relaxation and release force drift at high temperatures, while conventional fluorine-containing coatings may cause interface damage or silicone oil migration and contamination of the adhesive surface during high-speed peeling due to weak adhesion to the substrate. This results in decreased die-cutting efficiency and increased risk of adhesive contamination in applications such as high-end electronic tapes and optical film lamination. Furthermore, it is difficult to simultaneously meet the performance consistency requirements of solvent-free environmentally friendly processes and complex working conditions. Summary of the Invention

[0004] To address the increased risk of adhesive contamination caused by the use of silicone or fluorine-containing coatings in related coating materials, this application provides a solvent-free, high-temperature resistant silicone release film and its preparation method.

[0005] In a first aspect, this application provides a solvent-free, high-temperature resistant silicone release film, employing the following technical solution: A solvent-free, high-temperature resistant silicone release film is made from raw materials comprising the following components in parts by weight: 100 parts of terminal vinyl silicone oil; 15-35 parts of hyperbranched polysiloxane; 5-15 parts of multifunctional vinyl silane oligomer; 4-12 parts of crosslinking agent; 0.2-2.0 parts of platinum catalyst; 0.1-0.8 parts of alkynyl alcohol retarder; 0.5-3 parts of epoxy silane coupling agent; and 2-8 parts of MQ silicone resin.

[0006] By employing the above technical solutions, vinyl-terminated silicone oil serves as the basic polymer skeleton, providing film-forming substances and reactive vinyl groups. Hyperbranched polysiloxanes, with their three-dimensional structure, introduce physical entanglement points and free volumes into the cured network, enhancing its thermal stability and cohesive strength. Multifunctional vinyl silane oligomers act as highly active crosslinking points, increasing the crosslinking density of the final cured network. Platinum catalysts catalyze hydrosilylation reactions, ensuring room-temperature operability and rapid high-temperature curing. Simultaneously, alkynyl alcohol retarders, through reversible coordination with the platinum catalyst, temporarily inhibit its catalytic activity, providing a controllable pot life for the composition. During curing, the epoxy groups of the epoxy-based coupling agent interact with the substrate surface, while its siloxane portion participates in the condensation reaction, enhancing the adhesion between the release layer and the substrate. MQ silicone resin, as a peel force modifier, with its cage-like structure, can be uniformly dispersed in the system, regulating the magnitude and stability of the release force. The synergistic effect of these components results in a release film with high high-temperature stability, stable release force, and high adhesion to the substrate without the need for solvents.

[0007] Preferably, the vinyl-terminated silicone oil has a viscosity of 350–3500 mPa·s at 25°C and a vinyl content of 0.15–0.8 wt%; the hyperbranched polysiloxane has a weight-average molecular weight of 3000–10000.

[0008] By adopting the above technical solution, the vinyl-terminated silicone oil within this viscosity range can ensure that the release agent composition has suitable rheological properties, which is convenient for uniform mixing and degassing before coating, and also facilitates the formation of a uniform and defect-free wet film during coating. The vinyl content within this range can ensure that the cured network has a moderate crosslinking density. Too low a content will lead to incomplete curing and poor cohesive strength, while too high a content will increase the brittleness of the film layer. The molecular weight of the hyperbranched polysiloxane is controlled within this range, which can maintain good compatibility and dispersibility in the system. Too low a molecular weight will have limited reinforcing effect, while too high a molecular weight will affect the processing performance due to solubility or viscosity problems. This molecular weight range can provide structural advantages without increasing the initial viscosity of the system.

[0009] Preferably, the crosslinking agent has a hydrogen content of 0.3 to 1.2 wt%, and the crosslinking agent is at least one of a copolymer of methylhydrosiloxane and dimethylsiloxane, a terminal hydrogen-containing silicone oil, or a side-chain hydrogen-containing silicone oil.

[0010] By adopting the above technical solution, the hydrogen content of the crosslinking agent needs to match the total vinyl content in the terminal vinyl silicone oil and the multifunctional vinyl silane oligomer. This content range can ensure that sufficient and appropriate amounts of silane-hydrogen bonds participate in the addition reaction. Too low a hydrogen content will lead to insufficient crosslinking, loose cured film network, and poor heat resistance. Too high a hydrogen content will cause side reactions due to residual silane-hydrogen bonds in subsequent high-temperature environments, or lead to excessive curing shrinkage stress. Selecting a specific type of hydrogen-containing silicone oil can adjust the distribution of crosslinking points on the polymer chain. Side chain hydrogen can provide more uniform network crosslinking, while terminal hydrogen tends to form chain extension. Different types and structures of crosslinking agents work together to improve the mechanical and thermal properties of the final three-dimensional network.

[0011] Preferably, the multifunctional vinyl silane oligomer is at least one of tetravinyltetramethylcyclotetrasiloxane, divinyltetramethyldisiloxane, or vinyl-terminated silsesquioxane; the alkynyl alcohol retarder is at least one of ethynylcyclohexanol, methylbutynol, or dimethylhexynol; and the epoxy silane coupling agent is at least one of γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, or β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0012] By adopting the above technical solutions, the selected multifunctional vinyl silane oligomers are all small molecules or cage-like structures with high reactive functional group density and spatial accessibility. Under platinum catalysis, they can react rapidly with crosslinking agents, serving as rigid nodes to enhance the crosslinking density and high-temperature rigidity of the polymer network. The alkynyl alcohol retardant molecules have a strong coordination ability with the platinum central atom in their molecular structure, resulting in stable retardation effects. Moreover, their dissociation characteristics vary at different temperatures, making it easy to match the requirements of different process windows through formulation adjustments. At the same time, the selected epoxy silane coupling agent molecules contain siloxane groups that can participate in hydrosilylation or hydrolysis-condensation reactions, as well as epoxy groups that can form chemical bonds with hydroxyl groups and other groups on the substrate surface. This dual reaction mechanism ensures a strong and durable chemical bond between the release layer and various substrates.

[0013] Secondly, this application provides a method for preparing a solvent-free, high-temperature resistant organosilicon release film, employing the following technical solution: A method for preparing a solvent-free, high-temperature resistant silicone release film includes the following steps: S1. Mix and stir the terminal vinyl silicone oil, hyperbranched polysiloxane, multifunctional vinyl silane oligomer and MQ silicone resin to obtain a basic polymer blend; S2. Add epoxy silane coupling agent and alkynyl alcohol retarder to the basic polymer blend obtained in S1, stir evenly, and obtain modified inhibition mixture; S3. Add the hydrogen-containing silicone oil crosslinking agent in batches to the modified inhibition mixture obtained in S2, and disperse it to obtain a crosslinking agent dispersion system. S4. Add platinum catalyst to the crosslinking agent dispersion system obtained in S3, mix under light-protected conditions, and filter to obtain a solvent-free release agent composition. S5. The solvent-free release agent composition obtained in S4 is coated onto the surface of a corona-treated substrate, and then thermo-cured under gradient heating conditions. After being wound up and cured, a solvent-free high-temperature resistant silicone release film is obtained.

[0014] By adopting the above technical solution, step S1 aims to premix the basic polymers and functional additives uniformly to form a continuous phase in the reaction system, laying the foundation for the efficient and uniform reaction of subsequent components. In step S2, an epoxy silane coupling agent is added first to allow sufficient time for pre-dispersion and partial interaction with the basic polymer blend. Then, an alkynyl alcohol-based retarder is added to pre-regulate the activity of the platinum catalyst to be introduced later. This sequence helps avoid interference between the coupling agent and the retarder. In step S3, the crosslinking agent is introduced in batches to avoid premature reaction with residual trace catalysts or active sites in the system due to excessively high local concentrations of the crosslinking agent, ensuring that the crosslinking agent can effectively react with the catalyst. The crosslinking agent is evenly and stably dispersed throughout the mixture. In step S4, the platinum catalyst is added after the crosslinking agent has been evenly dispersed and the system has been inhibited by the delay agent. Mixing under light-protected conditions can prevent catalyst deactivation. Filtration removes mechanical impurities or trace gel particles introduced during dispersion, resulting in a uniform and stable release agent working solution. In step S5, the working solution is transferred to the substrate by coating. Corona treatment enhances the surface energy of the substrate, improving wettability and adhesion. Gradient temperature curing allows the hydrosilylation reaction to proceed in an orderly manner from slow to rapid, which is beneficial for complete solvent release, stress relaxation, and the formation of a dense and uniform cured film. The subsequent curing process allows unreacted groups to react further, promoting the release force to reach a stable state.

[0015] Preferably, in step S1, the mixing temperature is 20–40°C, the mixing time is 20–50 min, and the mixing speed is 300–800 rpm.

[0016] By adopting the above technical solution, the temperature range is close to room temperature, which can prevent the material from oxidizing or slightly cross-linking prematurely due to excessive temperature. At the same time, it is beneficial for each component to maintain good fluidity to promote mixing. Sufficient stirring time combined with medium stirring speed can ensure that the high viscosity end vinyl silicone oil, hyperbranched polysiloxane and solid MQ silicone resin powder achieve molecular-level uniform blending, while avoiding the introduction of too much air or local overheating of the material due to long-term high-speed stirring.

[0017] Preferably, in step S2, the stirring time is 10-30 min and the stirring temperature is 20-40℃; the order of adding the epoxy silane coupling agent and the alkynyl alcohol retardant is as follows: first add the epoxy silane coupling agent and stir for 5-15 min, then add the alkynyl alcohol retardant and continue stirring for 5-15 min.

[0018] By adopting the above technical solution, maintaining the stirring temperature helps to keep the system viscosity stable and facilitates the diffusion and mixing of materials. By specifying the total stirring time and limiting the stirring time for the first addition of the epoxy silane coupling agent, this stage allows the coupling agent molecules to diffuse and begin to interact with the silanols or other active sites in the base polymer, thereby realizing its surface modification function on the system. Subsequently, an alkynyl alcohol retarder is added and stirring continues. This step allows the retarder to be evenly distributed throughout the system and to establish a pre-contact with the potential active sites of the platinum catalyst to be added later, thereby ensuring that the delay inhibition effect takes effect immediately and evenly in subsequent steps.

[0019] Preferably, in step S3, the hydrogen-containing silicone oil crosslinking agent is added in 2 to 4 batches, with an interval of 5 to 15 minutes between adjacent batches, and dispersed at a speed of 200 to 600 rpm for 3 to 10 minutes after each addition.

[0020] By adopting the above technical solution, the crosslinking agent is added in batches, reducing the amount added at one time and avoiding the risk of generating gel particles due to violent reaction with trace active substances in the system caused by the instantaneous high concentration of the crosslinking agent in a local area. After each addition, it is dispersed at a medium-low speed. This shear force is sufficient to uniformly shear and disperse the viscous crosslinking agent throughout the modified inhibitory mixture without inducing unnecessary side reactions due to excessive shearing or high speed. The controlled interval time provides time for viscosity homogenization and heat dissipation, ensuring that the system is in a stable state before each addition, and finally obtaining a highly uniform crosslinking agent dispersion system.

[0021] Preferably, in step S4, the weight ratio of platinum catalyst to alkynyl alcohol retarder is 1:0.2 to 1:1.5, so that the viscosity of the obtained solvent-free release agent composition is 500 to 3000 mPa·s at 40°C, and the viscosity growth rate does not exceed 30% within 12 hours.

[0022] By adopting the above technical solution, the ratio of platinum catalyst to alkynyl alcohol retarder determines the balance between the pot life and curing rate of the release agent composition. This ratio range ensures that the retarder can inhibit catalytic activity at room temperature, allowing sufficient working time for coating operations, while the inhibition can be smoothly released during heat curing. The viscosity is controlled within a specific range, which is suitable for solvent-free coating processes, ensuring both high transferability and spreadability while preventing sagging. A viscosity increase rate of no more than 30% within 12 hours indicates that the crosslinking reaction of the system is inhibited within this time period, and the rheological properties of the composition remain stable, meeting the production requirements for storage and continuous coating.

[0023] Preferably, in step S5, the gradient temperature curing specifically involves: first curing at 70–100°C for 20–40 seconds, then increasing the temperature to 110–130°C for 15–25 seconds, and finally curing at 140–160°C for 10–20 seconds; the dry coating weight of the release film is 0.3–1.5 g / m³. 2 The coating speed is 50–150 m / min; the curing conditions are 25–40 °C for 24–72 h.

[0024] By adopting the above technical solution, the gradient temperature curing process follows the principles of chemical reaction kinetics. The purpose of the first temperature range of 70 to 100°C is to initiate the reaction, perform preliminary gelation, and allow low-molecular-weight volatiles to escape, avoiding the generation of bubbles from sudden high temperatures. The second temperature range of 110 to 130°C is the main curing stage, where the hydrosilylation reaction is rapidly completed, forming a basic network structure. The third temperature range of 140 to 160°C is the post-curing stage, which aims to promote the complete reaction of residual active groups and facilitate the rearrangement and compaction of the network structure, thereby improving the heat resistance and chemical stability of the release film. The coating dry weight controls the thickness of the release layer, affecting the release force and cost. The coating speed is matched with the curing time and oven length to ensure that the film material has sufficient residence time in each curing zone. The curing process is carried out under mild conditions, which releases the small amount of residual stress present after curing and allows the release force to reach a stable and reproducible equilibrium value over time.

[0025] In summary, this application has the following beneficial effects: 1. This application utilizes a composite system composed of terminal vinyl silicone oil, hyperbranched polysiloxane, and multifunctional vinyl silane oligomers to form a high-crosslink density network under platinum catalysis. The hyperbranched structure provides physical reinforcement, while the small-molecule multifunctional crosslinking points enhance network rigidity. The synergistic effect of these two factors enables the release film to achieve high-temperature resistance and dimensional stability. Simultaneously, the epoxy-based silane coupling agent combines with the organosilicon network and substrate to enhance adhesion. The introduction of alkynyl alcohol retarder and MQ silicone resin endows the composition with a suitable operating window and adjustable release force, thereby achieving the effect of ensuring high-temperature stability, dimensional stability, strong adhesion to the substrate, processability, and controllable release performance of the release film under solvent-free conditions.

[0026] 2. In this application, terminal vinyl silicone oils with specific viscosity and vinyl content and hyperbranched polysiloxanes with limited molecular weight range are preferred. This ensures that the composition has suitable processing rheological properties and final network structure strength. At the same time, crosslinking agents with specific hydrogen content are preferred to match the total amount of vinyl in the system, avoiding performance defects caused by insufficient or excessive crosslinking, thereby achieving the effect of stable and reliable release film performance.

[0027] 3. In this application, the basic components are first blended, and then coupling agent and delay agent are added for pre-modification. This order avoids component interference. The crosslinking agent is added to the delayed system in batches to effectively prevent premature local reaction and ensure uniform dispersion. Finally, the catalyst is added and gradient temperature is increased for curing. This curing procedure is matched with the reaction characteristics of the delayed system so that the curing reaction proceeds in an orderly manner from slow to fast, thereby obtaining a release film product with uniform appearance and dense structure. Attached Figure Description

[0028] Figure 1 This is a flowchart of a method for preparing a solvent-free, high-temperature resistant organosilicon release film according to this application. Detailed Implementation

[0029] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] Technical concept: Related coating materials use silicone or fluorine-containing coatings to regulate the surface energy of the release film to achieve controllable peeling. However, when faced with stringent industrial requirements such as high-frequency miniaturized die-cutting and silicone-free transfer, these traditional systems often struggle to achieve a balance between high-temperature dimensional stability, substrate adhesion strength, and precise adjustment of release force. Insufficient crosslinking density of linear silicone can easily lead to network relaxation and release force drift at high temperatures, while conventional fluorine-containing coatings may cause interface damage or silicone oil migration and contamination of the adhesive surface during high-speed peeling due to weak adhesion to the substrate. This results in decreased die-cutting efficiency and increased risk of adhesive contamination in applications such as high-end electronic tapes and optical film lamination. Furthermore, it is difficult to simultaneously meet the performance consistency requirements of solvent-free environmentally friendly processes and complex working conditions.

[0031] This application discloses a solvent-free, high-temperature resistant silicone release film and its preparation method; it is made from the following raw materials: terminal vinyl silicone oil, hyperbranched polysiloxane, multifunctional vinyl silane oligomer, crosslinking agent, platinum catalyst, alkynyl alcohol retarder, epoxy silane coupling agent, and MQ silicone resin; the preparation method is as follows: S1, mixing and stirring a portion of the raw materials; S2, adding epoxy silane coupling agent and alkynyl alcohol retarder to the basic polymer blend and stirring evenly; S3, adding hydrogen-containing silicone oil crosslinking agent to the modified inhibition mixture; S4, adding platinum catalyst to the crosslinking agent dispersion system; S5, coating the solvent-free release agent composition onto the substrate surface.

[0032] This application utilizes a composite system composed of terminal vinyl silicone oil, hyperbranched polysiloxane, and multifunctional vinyl silane oligomers to form a high-crosslink density network under platinum catalysis. The hyperbranched structure provides physical reinforcement, while the small-molecule multifunctional crosslinking points enhance network rigidity. The synergistic effect of these two factors enables the release film to achieve high-temperature resistance and dimensional stability. Simultaneously, the epoxy-based silane coupling agent combines with the organosilicon network and substrate to enhance adhesion. The introduction of alkynyl alcohol retarder and MQ silicone resin endows the composition with a suitable operating window and adjustable release force, thereby achieving the effect of ensuring high-temperature stability, dimensional stability, strong adhesion to the substrate, processability, and controllable release performance of the release film under solvent-free conditions.

[0033] Example 1: This example provides a solvent-free, high-temperature resistant silicone release film, made from raw materials comprising the following components by weight: 100 parts of vinyl-terminated silicone oil; 15 parts of hyperbranched polysiloxane; 5 parts of multifunctional vinyl silane oligomer; 4 parts of crosslinking agent; 0.2 parts of platinum catalyst; 0.1 parts of alkynyl alcohol retarder; 0.5 parts of epoxy silane coupling agent; and 2 parts of MQ silicone resin.

[0034] The vinyl-terminated silicone oil has a viscosity of 350 mPa·s at 25°C and a vinyl content of 0.15 wt%. The hyperbranched polysiloxane has a weight-average molecular weight of 3000. The crosslinking agent has a hydrogen content of 0.3 wt% and is a copolymer of methylhydrosiloxane and dimethylsiloxane. The multifunctional vinyl silane oligomer is tetravinyltetramethylcyclotetrasiloxane. The alkynyl alcohol retarder is ethynylcyclohexanol. The epoxy silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0035] The preparation method of the solvent-free, high-temperature resistant silicone release film is as follows: S1. Mix and stir the terminal vinyl silicone oil, hyperbranched polysiloxane, multifunctional vinyl silane oligomer and MQ silicone resin to obtain a basic polymer blend; The mixing temperature was 20℃, the mixing time was 20 min, and the mixing speed was 300 rpm.

[0036] S2. Add epoxy silane coupling agent and alkynyl alcohol retarder to the basic polymer blend obtained in S1, stir evenly, and obtain modified inhibition mixture; The stirring time was 10 minutes, and the stirring temperature was 20°C. The epoxy silane coupling agent and the alkynyl alcohol retarder were added in the following order: first, the epoxy silane coupling agent was added and stirred for 5 minutes, then the alkynyl alcohol retarder was added and stirred for another 5 minutes.

[0037] S3. Add the hydrogen-containing silicone oil crosslinking agent in batches to the modified inhibition mixture obtained in S2, and disperse it to obtain a crosslinking agent dispersion system. The hydrogen-containing silicone oil crosslinking agent was added in two batches, with a 5-minute interval between each batch. After each addition, the mixture was dispersed at 200 rpm for 3 minutes.

[0038] S4. Add platinum catalyst to the crosslinking agent dispersion system obtained in S3, mix under light-protected conditions, and filter to obtain a solvent-free release agent composition. The platinum catalyst and the alkynyl alcohol retarder are in a weight ratio of 1:0.2, which makes the viscosity of the resulting solvent-free release agent composition 500 mPa·s at 40°C and the viscosity increase rate 0% within 12 hours.

[0039] S5. The solvent-free release agent composition obtained in S4 is coated onto the surface of a corona-treated substrate, and then thermo-cured under gradient heating conditions. After being wound up and cured, a solvent-free high-temperature resistant silicone release film is obtained.

[0040] The gradient temperature curing process specifically involves: first curing at 70℃ for 40 seconds, then increasing the temperature to 110℃ for 25 seconds, and finally curing at 140℃ for 20 seconds; the dry coating weight of the release film is 0.3 g / m². 2The coating speed was 50 m / min. The curing conditions were 72 hours at 25°C.

[0041] Example 2: This example provides a solvent-free, high-temperature resistant silicone release film, made from raw materials comprising the following components in parts by weight: 100 parts of terminal vinyl silicone oil; 25 parts of hyperbranched polysiloxane; 10 parts of multifunctional vinyl silane oligomer; 8 parts of crosslinking agent; 1.1 parts of platinum catalyst; 0.45 parts of alkynyl alcohol retarder; 1.75 parts of epoxy silane coupling agent; and 5 parts of MQ silicone resin.

[0042] The vinyl-terminated silicone oil has a viscosity of 1925 mPa·s at 25°C and a vinyl content of 0.475 wt%. The hyperbranched polysiloxane has a weight-average molecular weight of 6500. The crosslinking agent has a hydrogen content of 0.75 wt% and is a hydrogen-terminated silicone oil. The multifunctional vinyl silane oligomer is divinyltetramethyldisiloxane. The alkynyl alcohol retarder is methylbutynol. The epoxy silane coupling agent is γ-glycidoxypropyltriethoxysilane.

[0043] The preparation method of the solvent-free, high-temperature resistant silicone release film is as follows: S1. Mix and stir the terminal vinyl silicone oil, hyperbranched polysiloxane, multifunctional vinyl silane oligomer and MQ silicone resin to obtain a basic polymer blend; The mixing temperature was 30℃, the mixing time was 35 minutes, and the mixing speed was 550 rpm.

[0044] S2. Add epoxy silane coupling agent and alkynyl alcohol retarder to the basic polymer blend obtained in S1, stir evenly, and obtain modified inhibition mixture; The stirring time was 20 minutes, and the stirring temperature was 30°C. The epoxy silane coupling agent and the alkynyl alcohol retarder were added in the following order: first, the epoxy silane coupling agent was added and stirred for 10 minutes, then the alkynyl alcohol retarder was added and stirred for another 10 minutes.

[0045] S3. Add the hydrogen-containing silicone oil crosslinking agent in batches to the modified inhibition mixture obtained in S2, and disperse it to obtain a crosslinking agent dispersion system. The hydrogen-containing silicone oil crosslinking agent was added in three batches, with a 10-minute interval between each batch. After each addition, the mixture was dispersed at 400 rpm for 6.5 minutes.

[0046] S4. Add platinum catalyst to the crosslinking agent dispersion system obtained in S3, mix under light-protected conditions, and filter to obtain a solvent-free release agent composition. The platinum catalyst and the alkynyl alcohol retarder are in a weight ratio of 1:0.85, which makes the viscosity of the resulting solvent-free release agent composition 1750 mPa·s at 40°C, and the viscosity increases by 15% over 12 hours.

[0047] S5. The solvent-free release agent composition obtained in S4 is coated onto the surface of a corona-treated substrate, and then thermo-cured under gradient heating conditions. After being wound up and cured, a solvent-free high-temperature resistant silicone release film is obtained.

[0048] The gradient temperature curing process specifically involves: first curing at 85℃ for 30 seconds, then increasing the temperature to 120℃ for 20 seconds, and finally curing at 150℃ for 15 seconds; the dry coating weight of the release film is 0.9 g / m². 2 The coating speed was 100 m / min. The curing conditions were 32.5℃ for 48 hours.

[0049] Example 3: This example provides a solvent-free, high-temperature resistant silicone release film, made from raw materials comprising the following components in parts by weight: 100 parts of terminal vinyl silicone oil; 35 parts of hyperbranched polysiloxane; 15 parts of multifunctional vinyl silane oligomer; 12 parts of crosslinking agent; 2.0 parts of platinum catalyst; 0.8 parts of alkynyl alcohol retarder; 3 parts of epoxy silane coupling agent; and 8 parts of MQ silicone resin.

[0050] The vinyl-terminated silicone oil has a viscosity of 3500 mPa·s at 25°C and a vinyl content of 0.8 wt%. The hyperbranched polysiloxane has a weight-average molecular weight of 10000. The crosslinking agent has a hydrogen content of 1.2 wt% and is a side-chain hydrogen-containing silicone oil. The multifunctional vinyl silane oligomer is a vinyl-terminated silsesquioxane. The alkynyl alcohol retarder is dimethylhexynyl alcohol. The epoxy silane coupling agent is β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0051] The preparation method of the solvent-free, high-temperature resistant silicone release film is as follows: S1. Mix and stir the terminal vinyl silicone oil, hyperbranched polysiloxane, multifunctional vinyl silane oligomer and MQ silicone resin to obtain a basic polymer blend; The mixing temperature was 40℃, the mixing time was 50 min, and the mixing speed was 800 rpm.

[0052] S2. Add epoxy silane coupling agent and alkynyl alcohol retarder to the basic polymer blend obtained in S1, stir evenly, and obtain modified inhibition mixture; The stirring time was 30 minutes, and the stirring temperature was 40°C. The epoxy silane coupling agent and the alkynyl alcohol retarder were added in the following order: first, the epoxy silane coupling agent was added and stirred for 15 minutes, then the alkynyl alcohol retarder was added and stirred for another 15 minutes.

[0053] S3. Add the hydrogen-containing silicone oil crosslinking agent in batches to the modified inhibition mixture obtained in S2, and disperse it to obtain a crosslinking agent dispersion system. The hydrogen-containing silicone oil crosslinking agent was added in four batches, with a 15-minute interval between each batch. After each addition, the mixture was dispersed at 600 rpm for 10 minutes.

[0054] S4. Add platinum catalyst to the crosslinking agent dispersion system obtained in S3, mix under light-protected conditions, and filter to obtain a solvent-free release agent composition. The platinum catalyst and the alkynyl alcohol retarder are in a weight ratio of 1:1.5, which makes the viscosity of the resulting solvent-free release agent composition 3000 mPa·s at 40°C, and the viscosity increases by 30% within 12 hours.

[0055] S5. The solvent-free release agent composition obtained in S4 is coated onto the surface of a corona-treated substrate, and then thermo-cured under gradient heating conditions. After being wound up and cured, a solvent-free high-temperature resistant silicone release film is obtained.

[0056] The gradient temperature curing process specifically involves: first curing at 100℃ for 20 seconds, then increasing the temperature to 130℃ for 15 seconds, and finally curing at 160℃ for 10 seconds; the dry coating weight of the release film is 1.5 g / m². 2 The coating speed was 150 m / min. The curing conditions were 24 hours at 40°C.

[0057] Comparative Example 1: This comparative example is the same as that in Example 1, except that the viscosity of the vinyl-terminated silicone oil at 25°C was changed from 350 mPa·s to 120 mPa·s. The rest of the contents are the same as those in Example 1.

[0058] Comparative Example 2: This comparative example is the same as that in Example 1, except that the vinyl content of the vinyl-terminated silicone oil is changed from 0.15wt% to 0.05wt%, and the rest is the same as in Example 1.

[0059] Comparative Example 3: This comparative example is the same as that in Example 1, except that the amount of hyperbranched polysiloxane is reduced from 15 parts to 5 parts, and the rest is the same as that in Example 1.

[0060] Comparative Example 4: This comparative example is the same as that in Example 1, except that the hydrogen content of the crosslinking agent is increased from 0.3wt% to 1.8wt%, and the rest is the same as in Example 1.

[0061] Comparative Example 5: This comparative example is the same as that in Example 1, except that the amount of alkynyl alcohol retarder is reduced from 0.1 parts to 0.01 parts, and the rest is the same as in Example 1.

[0062] Comparative Example 6: This comparative example refers to the content of Example 1, except that the gradient temperature curing procedure in step S5 is changed to single temperature curing, specifically: curing at 140°C for 85 seconds, the rest of the content is the same as Example 1.

[0063] Performance testing Sample preparation: According to the formulas and preparation methods described in Examples 1-3 and Comparative Examples 1-6, corresponding solvent-free release agent compositions were prepared and coated onto corona-treated polyethylene terephthalate film substrates of the same specifications. After curing and aging processes as specified by each, the samples were cut into standard test strips for subsequent performance testing.

[0064] High-temperature resistance test: Each release film sample was placed in a preheated 180°C drying oven and heat-treated for 30 minutes. After removal, it was cooled and equilibrated under standard temperature and humidity conditions for 2 hours. Subsequently, the release force of the film against standard pressure-sensitive tape after aging was tested according to the 180° peel method specified in national standard GB / T2792, and the rate of change of the release force relative to the initial release force before aging was calculated. This test aims to simulate the long-term effect of high-temperature process on release performance and verify its heat resistance stability. The test standard for performance parameters is GB / T2792.

[0065] Table 1: High-temperature resistance test data (after heat treatment at 180℃ for 30 min)

[0066] Release force and residual adhesion testing: According to the national standard GB / T4850, the initial release force of the release film is tested using the 180-degree peel method. A standard test tape is laminated onto the surface of the release film at a fixed pressure and speed. After standing for 20 minutes under standard temperature and humidity conditions, it is peeled off at a speed of 300 mm per minute, and the average force value during the peeling process is recorded as the release force. Subsequently, the test tape is immediately adhered to a clean stainless steel plate, and after standing for 20 minutes, it is peeled off at the same speed, and the peeling force value is recorded as the residual adhesion. This test is used to evaluate the ease of release film peeling and its ability to protect the adhesive tape's adhesion. The test standard for performance parameters is GB / T4850.

[0067] Table 2: Test data on peel performance at room temperature

[0068] Adhesion test: Using a sharp blade, a 1 mm spacing grid of squares is drawn on the release film coating surface, cutting until the coating is completely penetrated and reaches the substrate. After gently sweeping away debris with a soft brush, standard pressure-sensitive adhesive tape is firmly adhered to the grid area and quickly peeled off in a 180-degree direction. The extent of coating peeling in the grid area is checked and rated according to the grading standards specified in national standard GB / T9286. This test directly reflects the degree of adhesion of the coating to the substrate. The test standard for performance parameters is GB / T9286.

[0069] Dimensional thermal stability testing: Strips 150 mm long and 15 mm wide are cut along both the longitudinal and transverse directions of the release film, and 100 mm test segments are precisely marked on the strips. The strips are suspended in an oven preheated to 150°C and allowed to heat freely for 10 minutes before being removed and cooled to room temperature under standard temperature and humidity conditions. The change in distance between the marked points is precisely measured, and the longitudinal and transverse thermal shrinkage rates are calculated. This test is used to evaluate the material's dimensional retention ability after high-temperature treatment. The testing standards for performance parameters refer to GB / T12027.

[0070] Table 3: Coating adhesion and dimensional stability test data

[0071] Example Conclusion: As can be seen from Examples 1-3 and Comparative Example 1, and Table 1, maintaining an appropriate viscosity of the vinyl-terminated silicone oil is beneficial for forming a uniform and dense cured coating; while excessively low viscosity will reduce the cohesive strength and film-forming properties of the coating, resulting in insufficient network structure stability of the release film at high temperatures, manifested as accelerated performance degradation after heat resistance, and a decrease in its adhesion to the substrate and its own dimensional retention ability; this indicates that controlling the viscosity of the base polymer plays a role in obtaining a release film with good overall performance. As can be seen from Examples 1-3 and Comparative Example 2, and Table 1, sufficient vinyl groups in the vinyl-terminated silicone oil are a prerequisite for constructing a high crosslinking density network. However, if the vinyl group content is too low, there will be insufficient crosslinking points participating in the hydrosilylation reaction, resulting in a looser cured network. This weakens the network's resistance to deformation and degradation at high temperatures, reduces the thermal stability of the release force, and also affects the adhesion of the coating. This indicates that ensuring sufficient reactive functional group content is the basis for achieving the high-temperature resistance properties of the release film. Combining Examples 1-3 and Comparative Example 3 with Table 3, it can be seen that an appropriate amount of hyperbranched polysiloxane, as a network reinforcing phase, can form physical entanglement and spatial barrier in the matrix resin through its three-dimensional structure. When the amount is insufficient, the restriction effect on the movement of polymer chain segments is weakened, and the release film is more prone to shrinkage at high temperatures, resulting in decreased dimensional stability. This demonstrates the enhancing effect of hyperbranched polysiloxane in improving the physical and mechanical properties and high-temperature dimensional retention of the release film. Based on Examples 1-3 and Comparative Example 4, and in conjunction with Table 1, it can be seen that the hydrogen content of the crosslinking agent needs to achieve stoichiometric balance with the total amount of vinyl groups in the system. Excessive hydrogen content can increase the crosslinking density, but it can also lead to excessive local crosslinking, network stress concentration, and side reactions of residual silane bonds at high temperatures, affecting the uniformity and stability of the network, resulting in increased performance degradation after high-temperature aging. This indicates that accurately matching the proportion of reactive groups helps to obtain a stable cured network. Based on Examples 1-3 and Comparative Example 5, and in conjunction with Tables 1 and 2, it can be seen that sufficient amounts of alkynyl alcohol retarder can ensure the process applicability of the release agent composition; however, if the amount of retarder is too small, its inhibition efficiency on the platinum catalyst will be insufficient, which will lead to a shortened pot life of the composition before coating and a faster increase in viscosity, thereby affecting the coating uniformity. Combining Examples 1-3 and Comparative Example 6 with Table 3, it can be seen that the gradient temperature curing process, compared to single-temperature curing, better conforms to the kinetics of the hydrosilylation reaction and the physical changes required during film curing. Gradient temperature increases allow for a gradual initiation of the reaction, sufficient escape of small molecules, and orderly network formation. Eliminating the gradient process and directly curing at high temperature leads to an excessively rapid reaction and increased internal stress, thereby affecting the dimensional stability of the release film at high temperatures, manifested as an increase in thermal shrinkage. This indicates that the improved curing process has an impact on achieving the densification and stability of the product's microstructure.

[0072] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A solvent-free, high-temperature resistant silicone release film, characterized in that, It is made from raw materials containing the following components in parts by weight: 100 parts of terminal vinyl silicone oil; 15-35 parts of hyperbranched polysiloxane; 5-15 parts of multifunctional vinyl silane oligomer; 4-12 parts of crosslinking agent; 0.2-2.0 parts of platinum catalyst; 0.1-0.8 parts of alkynyl alcohol retarder; 0.5-3 parts of epoxy silane coupling agent; and 2-8 parts of MQ silicone resin.

2. The solvent-free, high-temperature resistant silicone release film according to claim 1, characterized in that, The vinyl-terminated silicone oil has a viscosity of 350–3500 mPa·s at 25°C and a vinyl content of 0.15–0.8 wt%; the hyperbranched polysiloxane has a weight-average molecular weight of 3000–10000.

3. The solvent-free, high-temperature resistant silicone release film according to claim 1, characterized in that, The crosslinking agent has a hydrogen content of 0.3 to 1.2 wt%, and the crosslinking agent is at least one of a copolymer of methylhydrosiloxane and dimethylsiloxane, a terminal hydrogen-containing silicone oil, or a side-chain hydrogen-containing silicone oil.

4. The solvent-free, high-temperature resistant silicone release film according to claim 1, characterized in that, The multifunctional vinyl silane oligomer is at least one of tetravinyltetramethylcyclotetrasiloxane, divinyltetramethyldisiloxane, or vinyl-terminated silsesquioxane; the alkynyl alcohol retarder is at least one of ethynylcyclohexanol, methylbutynol, or dimethylhexynol; and the epoxy silane coupling agent is at least one of γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, or β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

5. A method for preparing a solvent-free, high-temperature resistant organosilicon release film, characterized in that, The solvent-free, high-temperature resistant silicone release film according to any one of claims 1-4 comprises the following steps: S1. Mix and stir the terminal vinyl silicone oil, hyperbranched polysiloxane, multifunctional vinyl silane oligomer and MQ silicone resin to obtain a basic polymer blend; S2. Add epoxy silane coupling agent and alkynyl alcohol retarder to the basic polymer blend obtained in S1, stir evenly, and obtain modified inhibition mixture; S3. Add the hydrogen-containing silicone oil crosslinking agent in batches to the modified inhibition mixture obtained in S2, and disperse it to obtain a crosslinking agent dispersion system. S4. Add platinum catalyst to the crosslinking agent dispersion system obtained in S3, mix under light-protected conditions, and filter to obtain a solvent-free release agent composition. S5. The solvent-free release agent composition obtained in S4 is coated onto the surface of a corona-treated substrate, and then thermo-cured under gradient heating conditions. After being wound up and cured, a solvent-free high-temperature resistant silicone release film is obtained.

6. The method for preparing a solvent-free, high-temperature resistant organosilicon release film according to claim 5, characterized in that, In step S1, the mixing temperature is 20–40°C, the mixing time is 20–50 min, and the mixing speed is 300–800 rpm.

7. The method for preparing a solvent-free, high-temperature resistant organosilicon release film according to claim 5, characterized in that, In step S2, the stirring time is 10-30 min and the stirring temperature is 20-40℃. The order of adding the epoxy silane coupling agent and the alkynyl alcohol retardant is as follows: first add the epoxy silane coupling agent and stir for 5-15 min, then add the alkynyl alcohol retardant and continue stirring for 5-15 min.

8. The method for preparing a solvent-free, high-temperature resistant organosilicon release film according to claim 5, characterized in that, In step S3, the hydrogen-containing silicone oil crosslinking agent is added in 2 to 4 batches, with an interval of 5 to 15 minutes between adjacent batches. After each addition, the mixture is dispersed at a speed of 200 to 600 rpm for 3 to 10 minutes.

9. The method for preparing a solvent-free, high-temperature resistant organosilicon release film according to claim 5, characterized in that, In step S4, the weight ratio of platinum catalyst to alkynyl alcohol retarder is 1:0.2 to 1:1.5, so that the viscosity of the resulting solvent-free release agent composition is 500 to 3000 mPa·s at 40°C, and the viscosity growth rate does not exceed 30% within 12 hours.

10. The method for preparing a solvent-free, high-temperature resistant organosilicon release film according to claim 5, characterized in that, In step S5, the gradient temperature curing process is as follows: first, cure at 70–100℃ for 20–40 seconds, then increase the temperature to 110–130℃ for 15–25 seconds, and finally cure at 140–160℃ for 10–20 seconds; the dry weight of the release film coating is 0.3–1.5 g / m³. 2 The coating speed is 50–150 m / min; the curing conditions are 25–40 °C for 24–72 hours.

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