A silicone pressure-sensitive adhesive suitable for protecting a hard coating film, a preparation method and applications thereof

Abstract

The application discloses a kind of organic silicon pressure sensitive adhesive suitable for the protection of hard coating film, preparation method and application, belong to the technical field of organic silicon pressure sensitive adhesive material, the organic silicon pressure sensitive adhesive is realized to the protection of hard coating film using a kind of organic silicon modified borate, collocation vinyl silicone oil, crosslinking agent, anchoring agent, catalyst, film tearing force is stable and does not climb, silicon transfer degree is low, does not affect the smoothness of hard coating film itself.

Description

Technical Field

[0001] This invention relates to the field of silicone pressure-sensitive adhesive protective film technology, and particularly to a silicone pressure-sensitive adhesive suitable for curing coating film protection, its preparation method, and its application. Background Technology

[0002] 3D curved screens and foldable screen phones are increasingly favored by the market, making screen protectors for their flexible displays indispensable and crucial for protecting the bare screen. Conventional screen protector substrates are typically made of polyethylene terephthalate (PET), thermoplastic polyurethane (TPU), and polyimide (PI), which have poor scratch resistance and no fingerprint resistance. Currently, the mainstream choice in the market is to coat a 1-3µm colorless transparent hardened coating (HC) film onto the surface of the conventional base film to meet the application requirements of flexible screen protectors.

[0003] The conventional hardened coating is based on a polyurethane-modified acrylic system, with added fluorine-containing additives to improve the scratch resistance and slip properties of the HC liquid. This is then coated onto a conventional base film and cured by UV light to form the HC film. This type of hardened coating film has excellent hardness, providing sufficient protection for the underlying conventional base film, optically transparent adhesive, and flexible bare screen.

[0004] Before the aforementioned 3D screen mobile phones are shipped to the end market, a protective film is needed to protect the HC film. This protective film mainly consists of a layer of acrylic or silicone pressure-sensitive adhesive coated on a PET film, which has a certain peel force on the HC film (generally 1-4 g / inch) without affecting the smoothness of the HC film itself. Conventional acrylic pressure-sensitive adhesives exhibit peel force creep and noise when peeling off the film, affecting the end customer's experience; while silicone pressure-sensitive adhesives have stable peel force, but they themselves have a certain degree of silicone transfer, which reduces the smoothness of the HC film itself, also failing to meet the needs of end customers. Therefore, there is an urgent need for a silicone pressure-sensitive adhesive suitable for protecting hardened coating films to solve the problems existing in the above-mentioned technologies. Summary of the Invention

[0005] The purpose of this invention is to provide an organosilicon pressure-sensitive adhesive suitable for protecting hardened coating films. By synthesizing an organosilicon-modified borate ester and combining it with vinyl silicone oil, the hardened coating film can be protected. This results in stable tear force without creeping, low silicone transfer, and no impact on the smoothness of the hardened coating film itself.

[0006] Another object of the present invention is to provide a method for preparing such an organosilicon pressure-sensitive adhesive suitable for curing coating film protection.

[0007] Another object of the present invention is to provide an application of this silicone pressure-sensitive adhesive suitable for the protection of hardened coating films.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] An organosilicon pressure-sensitive adhesive suitable for curing coating film protection comprises vinyl silicone oil, organosilicon-modified borate ester, crosslinking agent, anchoring agent and catalyst.

[0010] In this invention, the vinyl silicone oil component is obtained by uniformly stirring the following raw materials in a reaction vessel:

[0011] 40-60 parts by weight of vinyl silicone oil A, 15-25 parts by weight of vinyl silicone oil B, 20-40 parts by weight of vinyl silicone oil C and 0.1-0.3 parts by weight of ethynylcyclohexanol.

[0012] Among them, vinyl silicone oil A has a viscosity of 9000–11000 mPa·s and a vinyl content of 0.12–0.16 wt%; vinyl silicone oil B has a viscosity of 54000–66000 mPa·s and a vinyl content of 0.08–0.10 wt%; and vinyl silicone oil C has a viscosity of 1000–1100 mPa·s and a vinyl content of 0.21–0.25 wt%.

[0013] In this invention, the organosilicon-modified borate ester component is obtained by reacting the following raw materials in a vacuum distillation reactor:

[0014] 5-10 parts by weight of triallyl borate, 4-8 parts by weight of tri(methacrylate-ethyl) borate and 5-9 parts by weight of tri(methacrylate-ethyl) borate; 40-80 parts by weight of dimethylisopropylsilane.

[0015] In this invention, the crosslinking agent component is a hydrogen-based polysiloxane with a hydrogen content of 0.95-1.05%; preferably, the structure of the hydrogen-based polysiloxane as the crosslinking agent component is (CH3)3SiO[(CH3)2SiO]. m [(CH3)(H)SiO] n Si(CH3)3, where m is a natural number greater than or equal to 0 and less than 3, and n is a natural number greater than or equal to 0.

[0016] In this invention, the anchoring agent component is a hydrogen-based polysiloxane containing one or more of epoxy, ether, and acyl groups; preferably, the hydrogen-based polysiloxane used as the anchoring agent component has the specific structure (R1)(CH3)2SiO[(CH3)(H)SiO] k [(CH3)(X)SiO] j Si(CH3)2(R2), where R1 and R2 are alkyl or H, X is an epoxy, ether or acyl group, and k and j are natural numbers, with 1≤k≤7 and 1≤j≤4.

[0017] In this invention, the catalyst component is a platinum catalyst formed by coordination of platinum and divinyltetramethyldisiloxane, wherein the platinum content is 4000-6000 ppm.

[0018] In this invention, the amounts of each component by weight are as follows: 100 parts of vinyl silicone oil, 6-12 parts of organosilicon-modified borate ester, 1.4-1.6 parts of crosslinking agent, 0.8-1.2 parts of anchoring agent, and 1.2-1.4 parts of catalyst.

[0019] On the other hand, the present invention also provides a method for preparing the aforementioned silicone pressure-sensitive adhesive suitable for curable coating film protection, comprising the following steps:

[0020] 1) Preparation of organosilicon-modified borate ester component: 5-10 parts by weight of triallyl borate, 4-8 parts by weight of tri(methacrylate ethyl) borate and 5-9 parts by weight of tri(methacrylate ethyl) borate are added to a vacuum distillation reactor, stirred evenly, and then 40-80 parts by weight of dimethyl isopropylsilane are added and stirred to obtain organosilicon-modified borate ester component.

[0021] 2) Preparation of vinyl silicone oil component: 40-60 parts by weight of vinyl silicone oil A, 15-25 parts by weight of vinyl silicone oil B, 20-40 parts by weight of vinyl silicone oil C and 0.1-0.3 parts by weight of ethynylcyclohexanol are added sequentially to a reaction vessel and stirred at room temperature to obtain the vinyl silicone oil component.

[0022] 3) Preparation of pressure-sensitive adhesive: Add 100 parts of vinyl silicone oil component to 120 parts of ethyl acetate and stir for 9-12 minutes. Then, while stirring, add 6-12 parts of organosilicon modified borate ester component, 1.4-1.6 parts of crosslinking agent component, and 0.8-1.2 parts of anchoring agent component. Stir for 10 minutes. Finally, add 1.2-1.4 parts of catalyst component. After all the components are added, stir to obtain the final pressure-sensitive adhesive bath solution.

[0023] 4) Curing of pressure-sensitive adhesive: The prepared bath solution is applied to the PET film and then placed in an oven for curing to obtain an organosilicon pressure-sensitive adhesive film suitable for hardened coating film protection.

[0024] In this invention, the stirring temperature in step 1) is 80-120℃ and the stirring time is 4-6 hours; the stirring time at room temperature in step 2) is 4-6 hours; the stirring time in step 3) is 14-16 minutes; and the oven temperature in step 4) is 145-155℃ and the curing time is 1.5-2 minutes.

[0025] On the other hand, the aforementioned silicone pressure-sensitive adhesives suitable for curable coating film protection or the silicone pressure-sensitive adhesives prepared by the aforementioned methods are preferably suitable for curable coating film protection applications in the field of electronic protective films.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1) The peeling force of the silicone pressure-sensitive adhesive of the present invention on the colorless transparent hardened coating (HC) film is controllable. By changing the amount of silicone-modified borate ester component added, the peeling force is stabilized in the range of 1 to 4 g / inch. Generally, if the peeling force is <1 g / inch, there is a risk that the silicone pressure-sensitive adhesive film will fall off from the HC film. If the peeling force is >4 g / inch, the peeling will feel heavy and affect the end customer's peeling experience.

[0028] 2) The silicone pressure-sensitive adhesive of the present invention has a low degree of silicon transfer to the colorless transparent curable coating (HC) film, so it will not affect the slip properties of the HC film itself; conventional silicone pressure-sensitive adhesives use MQ resin as a tackifier. MQ resin is an inert mixture with a wide molecular weight distribution range. Inevitably, small siloxane molecules will migrate to the surface of the HC film, thereby reducing the slip properties of the HC film.

[0029] 3) In this invention, three vinyl silicone oils with different vinyl structures are combined with a crosslinking agent (hydrogen-containing silicone oil) to achieve stable peel force. The vinyl positions and vinyl contents in the three vinyl silicone rubbers are different, providing multiple active sites for crosslinking reactions in space, thereby achieving a high crosslinking density. After adding the organosilicon tackifier, the peel force tends to be stable and will not increase due to high temperature baking and room temperature storage time verification.

[0030] 5) In this invention, a special organosilicon-modified borate ester component is synthesized as a tackifier for organosilicon pressure-sensitive adhesive to increase peel strength, while avoiding silicon transfer caused by conventional MQ resin as a tackifier; the aforementioned organosilicon-modified borate ester component has vinyl functional groups, which undergo an addition reaction with the crosslinking agent (containing hydrogen silicone oil) to avoid silicon transfer as much as possible; the borate ester structure forms intermolecular forces with the polar groups on the HC film surface to achieve a certain range of tackification effect. Detailed Implementation

[0031] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims of the present invention.

[0032] The present invention will be further explained and illustrated below through more specific embodiments, but these do not constitute any limitation.

[0033] In all embodiments, unless otherwise stated, all quantities are by weight; for ease of description, the sources of the main raw materials used in each embodiment and comparative example are as follows:

[0034] Vinyl silicone oil A: Hesheng HS-10000, viscosity 9000~11000mPa·s, vinyl content 0.12-0.16%, volatile matter ≤1.5%;

[0035] Vinyl silicone oil B: Hesheng HS-60000, viscosity 54000~66000mPa·s, vinyl content 0.08-0.10%, volatile matter ≤1.5%;

[0036] Vinyl silicone oil C: Runhe RH-Vi305B, viscosity 1000mPa·s, vinyl content 0.21-0.25%, volatile matter ≤1%;

[0037] Triallyl borate: Aladdin, analytical grade;

[0038] Tris(methacrylate ethyl) borate: Aladdin, analytical grade

[0039] Tris(ethyl acrylate) borate: Aladdin, analytical grade

[0040] Dimethylisopropylsilane: Aladdin, analytical grade

[0041] Ethynylcyclohexanol: Aladdin, analytical grade;

[0042] Ethyl acetate: Aladdin, analytical grade;

[0043] Crosslinking agent: Runhe, RH510;

[0044] Anchoring agent: Tianqi New Materials, SK-M02 or SK-M03;

[0045] Catalyst: Heraeus, platinum content 5000ppm.

[0046] Example 1:

[0047] 1) Preparation of organosilicon-modified borate ester components:

[0048] Five parts by weight of triallyl borate, eight parts by weight of tri(methacrylate ethyl) borate and seven parts by weight of tri(methacrylate ethyl) borate were added to a vacuum distillation reactor, stirred evenly, and then 80 parts by weight of dimethyl isopropylsilane were added and stirred at 80°C for 6 hours to obtain the organosilicon-modified borate ester component.

[0049] 2) Preparation of vinyl silicone oil component: 40 parts by weight of vinyl silicone oil A, 20 parts by weight of vinyl silicone oil B, 40 parts by weight of vinyl silicone oil C and 0.22 parts by weight of ethynylcyclohexanol were added to the reaction vessel in sequence and stirred at room temperature for 4 hours to obtain the vinyl silicone oil component.

[0050] 3) Preparation of pressure-sensitive adhesive: Add 100 parts of vinyl silicone oil component to 120 parts of ethyl acetate and stir for 10 minutes. Then, while stirring, add 6 parts of organosilicon modified borate ester component, 1.5 parts of crosslinking agent component, and 1.0 part of anchoring agent component and stir for 10 minutes. Finally, add 1.3 parts of catalyst component and stir for 15 minutes after all the components have been added to obtain the final pressure-sensitive adhesive bath.

[0051] 4) Curing of pressure-sensitive adhesive: The prepared bath solution is applied to a 50um PET film and then placed in a 150℃ oven for curing for 1.5 minutes to obtain the final pressure-sensitive adhesive protective film; the HC film is then laminated for performance testing, and its performance parameters are shown in Table 1.

[0052] Example 2:

[0053] 1) Preparation of organosilicon-modified borate ester components:

[0054] 10 parts by weight of triallyl borate, 4 parts by weight of tri(methacrylate ethyl) borate and 6 parts by weight of tri(methacrylate ethyl) borate were added to a vacuum distillation reactor, stirred evenly, and then 80 parts by weight of dimethyl isopropylsilane were added and stirred at 100°C for 5 hours to obtain the organosilicon-modified borate ester component.

[0055] 2) Preparation of vinyl silicone oil component: 60 parts by weight of vinyl silicone oil A, 15 parts by weight of vinyl silicone oil B, 25 parts by weight of vinyl silicone oil C and 0.22 parts by weight of ethynylcyclohexanol were added to the reaction vessel in sequence and stirred at room temperature for 6 hours to obtain the vinyl silicone oil component.

[0056] 3) Preparation of pressure-sensitive adhesive: Add 100 parts of vinyl silicone oil component to 120 parts of ethyl acetate and stir for 10 minutes. Then, while stirring, add 8 parts of organosilicon modified borate ester component, 1.5 parts of crosslinking agent component, and 1.0 part of anchoring agent component and stir for 10 minutes. Finally, add 1.3 parts of catalyst component and stir for 15 minutes after all the components have been added to obtain the final pressure-sensitive adhesive bath.

[0057] 4) Curing of pressure-sensitive adhesive: The prepared bath solution is applied to a 50um PET film and then placed in a 150℃ oven for curing for 1.5 minutes to obtain the final pressure-sensitive adhesive protective film; the HC film is then laminated for performance testing, and its performance parameters are shown in Table 1.

[0058] Example 3:

[0059] 1) Preparation of organosilicon-modified borate ester components:

[0060] 7 parts by weight of triallyl borate, 8 parts by weight of tri(methacrylate ethyl) borate and 5 parts by weight of tri(methacrylate ethyl) borate were added to a vacuum distillation reactor, stirred evenly, and then 80 parts by weight of dimethyl isopropylsilane were added and stirred at 120°C for 4 hours to obtain the organosilicon-modified borate ester component.

[0061] 2) Preparation of vinyl silicone oil component: 55 parts by weight of vinyl silicone oil A, 25 parts by weight of vinyl silicone oil B, 20 parts by weight of vinyl silicone oil C and 0.22 parts by weight of ethynylcyclohexanol were added to the reaction vessel in sequence and stirred at room temperature for 6 hours to obtain the vinyl silicone oil component.

[0062] 3) Preparation of pressure-sensitive adhesive: Add 100 parts of vinyl silicone oil component to 120 parts of ethyl acetate and stir for 10 minutes. Then, while stirring, add 10 parts of organosilicon modified borate ester component, 1.5 parts of crosslinking agent component, and 1.0 part of anchoring agent component and stir for 10 minutes. Finally, add 1.3 parts of catalyst component and stir for 15 minutes after all the components have been added to obtain the final pressure-sensitive adhesive bath.

[0063] 4) Curing of pressure-sensitive adhesive: The prepared bath solution is applied to a 50um PET film and then placed in a 150℃ oven for curing for 1.5 minutes to obtain the final pressure-sensitive adhesive protective film; the HC film is then laminated for performance testing, and its performance parameters are shown in Table 1.

[0064] Example 4:

[0065] 1) Preparation of organosilicon-modified borate ester components:

[0066] Five parts by weight of triallyl borate, six parts by weight of tri(methacrylate ethyl) borate and nine parts by weight of tri(methacrylate ethyl) borate were added to a vacuum distillation reactor, stirred evenly, and then 80 parts by weight of dimethyl isopropylsilane were added and stirred at 120°C for 5 hours to obtain the organosilicon-modified borate ester component.

[0067] 2) Preparation of vinyl silicone oil component: 50 parts by weight of vinyl silicone oil A, 20 parts by weight of vinyl silicone oil B, 30 parts by weight of vinyl silicone oil C and 0.22 parts by weight of ethynylcyclohexanol were added to the reaction vessel in sequence and stirred at room temperature for 5 hours to obtain the vinyl silicone oil component.

[0068] 3) Preparation of pressure-sensitive adhesive: Add 100 parts of vinyl silicone oil component to 120 parts of ethyl acetate and stir for 10 minutes. Then, while stirring, add 12 parts of organosilicon modified borate ester component, 1.5 parts of crosslinking agent component, and 1.0 part of anchoring agent component and stir for 10 minutes. Finally, add 1.3 parts of catalyst component and stir for 15 minutes after all the components have been added to obtain the final pressure-sensitive adhesive bath.

[0069] 4) Curing of pressure-sensitive adhesive: The prepared bath solution is applied to a 50um PET film and then placed in a 150℃ oven for curing for 1.5 minutes to obtain the final pressure-sensitive adhesive protective film; the HC film is then laminated for performance testing, and its performance parameters are shown in Table 1.

[0070] Comparative Example 1:

[0071] 1) Organosilicon MQ resin (similar in function to the organosilicon-modified borate ester component mentioned above):

[0072] The aforementioned is a 75% solids content methyl MQ silicone tackifier, wherein the structural formula of the methyl MQ silicone tackifier is [(CH3)3SiO 1 / 2 ] a [SiO 4 / 2 ] c ;wherein [(CH3)3SiO 1 / 2 ] a For M-units, [SiO 4 / 2 ] c The unit is Q; the ratio of M unit to Q unit is a / c, which is 0.6-0.8; the powder bulk density is 0.2-0.3 g / cm³. 3 Molecular weight: 4000-6000; Average particle size: 90-110μm; Hydroxyl content: ≤0.5%

[0073] 2) Preparation of vinyl silicone oil component: 40 parts by weight of vinyl silicone oil A, 20 parts by weight of vinyl silicone oil B, 40 parts by weight of vinyl silicone oil C and 0.22 parts by weight of ethynylcyclohexanol were added to the reaction vessel in sequence and stirred at room temperature for 5 hours to obtain the vinyl silicone oil component.

[0074] 3) Preparation of pressure-sensitive adhesive: Add 100 parts of vinyl silicone oil component to 120 parts of ethyl acetate and stir for 10 minutes. Then, while stirring, add 6 parts of organosilicon MQ resin, 1.5 parts of crosslinking agent component, and 1.0 part of anchoring agent component and stir for 10 minutes. Finally, add 1.3 parts of catalyst component. After all the components are added, stir for 15 minutes to obtain the final pressure-sensitive adhesive bath.

[0075] 4) Curing of pressure-sensitive adhesive: The prepared bath solution is applied to a 50um PET film and then placed in a 150℃ oven for curing for 1.5 minutes to obtain the final pressure-sensitive adhesive protective film; the HC film is then laminated for performance testing, and its performance parameters are shown in Table 2.

[0076] Comparative Example 2:

[0077] 1) Organosilicon MQ resin (similar in function to the organosilicon-modified borate ester component mentioned above):

[0078] The aforementioned is a 75% solids content methyl MQ silicone tackifier, wherein the structural formula of the methyl MQ silicone tackifier is [(CH3)3SiO 1 / 2 ] a [SiO 4 / 2 ] c ;wherein [(CH3)3SiO 1 / 2 ] a For M-units, [SiO 4 / 2 ] c The unit is Q; the ratio of M unit to Q unit is a / c, which is 0.6-0.8; the powder bulk density is 0.2-0.3 g / cm³. 3 Molecular weight: 4000-6000; Average particle size: 90-110μm; Hydroxyl content: ≤0.5%

[0079] 2) Preparation of vinyl silicone oil component: 50 parts by weight of vinyl silicone oil A, 20 parts by weight of vinyl silicone oil B, 30 parts by weight of vinyl silicone oil C and 0.22 parts by weight of ethynylcyclohexanol were added to the reaction vessel in sequence and stirred at room temperature for 6 hours to obtain the vinyl silicone oil component.

[0080] 3) Preparation of pressure-sensitive adhesive: Add 100 parts of vinyl silicone oil component to 120 parts of ethyl acetate and stir for 10 minutes. Then, while stirring, add 12 parts of organosilicon MQ resin, 1.5 parts of crosslinking agent component, and 1.0 part of anchoring agent component and stir for 10 minutes. Finally, add 1.3 parts of catalyst component. After all the components are added, stir for 15 minutes to obtain the final pressure-sensitive adhesive bath.

[0081] 4) Curing of pressure-sensitive adhesive: The prepared bath solution is applied to a 50um PET film and then placed in a 150℃ oven for curing for 1.5 minutes to obtain the final pressure-sensitive adhesive protective film; the HC film is then laminated for performance testing, and its performance parameters are shown in Table 2.

[0082] Comparative Example 3

[0083] 1) Preparation of organosilicon-modified borate ester components:

[0084] 7 parts by weight of triallyl borate, 8 parts by weight of tri(methacrylate ethyl) borate and 5 parts by weight of tri(methacrylate ethyl) borate were added to a vacuum distillation reactor, stirred evenly, and then 80 parts by weight of dimethyl isopropylsilane were added and stirred at 120°C for 4 hours to obtain the organosilicon-modified borate ester component.

[0085] 2) Preparation of vinyl silicone oil component: 60 parts by weight of vinyl silicone oil A, 40 parts by weight of vinyl silicone oil C and 0.22 parts by weight of ethynylcyclohexanol were added sequentially to a reaction vessel and stirred at room temperature for 6 hours to obtain the vinyl silicone oil component.

[0086] 3) Preparation of pressure-sensitive adhesive: Add 100 parts of vinyl silicone oil component to 120 parts of ethyl acetate and stir for 10 minutes. Then, while stirring, add 10 parts of tributyl borate, 1.5 parts of crosslinking agent component, and 1.0 part of anchoring agent component and stir for 10 minutes. Finally, add 1.3 parts of catalyst component. After all the components are added, stir for 15 minutes to obtain the final pressure-sensitive adhesive bath.

[0087] 4) Curing of pressure-sensitive adhesive: The prepared bath solution is applied to a 50um PET film and then placed in a 150℃ oven for curing for 1.5 minutes to obtain the final pressure-sensitive adhesive protective film; the HC film is then laminated for performance testing, and its performance parameters are shown in Table 2.

[0088] Comparative Example 4

[0089] 1) Use tributyl borate directly;

[0090] 2) Preparation of vinyl silicone oil component: 55 parts by weight of vinyl silicone oil A, 25 parts by weight of vinyl silicone oil B, 20 parts by weight of vinyl silicone oil C and 0.22 parts by weight of ethynylcyclohexanol were added to the reaction vessel in sequence and stirred at room temperature for 6 hours to obtain the vinyl silicone oil component.

[0091] 3) Preparation of pressure-sensitive adhesive: Add 100 parts of vinyl silicone oil component to 120 parts of ethyl acetate and stir for 10 minutes. Then, while stirring, add 10 parts of tributyl borate, 1.5 parts of crosslinking agent component, and 1.0 part of anchoring agent component and stir for 10 minutes. Finally, add 1.3 parts of catalyst component. After all the components are added, stir for 15 minutes to obtain the final pressure-sensitive adhesive bath.

[0092] 4) Curing of pressure-sensitive adhesive: The prepared bath solution is applied to a 50um PET film and then placed in a 150℃ oven for curing for 1.5 minutes to obtain the final pressure-sensitive adhesive protective film; the HC film is then laminated for performance testing, and its performance parameters are shown in Table 2.

[0093] The performance tested in Examples 1-4 and Comparative Examples 1-4 above is as follows:

[0094] 1. Tearing force test: The pressure-sensitive tape (10um thickness) coated on the PET film and fully cured was bonded to the HC film, and then cut into standard test pieces with a width of 25.4mm and a length of 300mm. It was aged at room temperature for 1 day / 7 days and at 70℃ for 1 day / 7 days. During the test, the pressure-sensitive tape was peeled 180° with the pressure-sensitive tape facing upward (peeling speed of 300mm / min). The test result is the tearing force. The test environment is temperature 23±2℃ and relative humidity 50±5% RH.

[0095] 2. Low Silicon Transfer Test: The smoothness of the HC membrane surface was tested using a friction coefficient tester (equipment model: YH-9819, test standard: GB 10006-88). The test results are expressed as the dynamic friction coefficient U. d Presented to characterize the degree of silicon transfer from the pressure-sensitive tape to the HC film; where: U d The smaller the value, the smoother the HC membrane surface, indicating a lower degree of silicon transfer. Generally, the initial U of the HC membrane... d The value is around 0.10. After applying the pressure-sensitive tape, the U value of the HC film... d A value ≤ 0.3 indicates a low degree of silicon transfer, which meets the technical requirements for HC film protection.

[0096] Table 1 shows the performance test results for Examples 1-4:

[0097]

[0098] Table 2 shows the performance test results for Comparative Examples 1-4:

[0099]

[0100]

[0101] In summary:

[0102] As can be seen from Examples 1, 2, 3, and 4, the silicone pressure-sensitive adhesive of the present invention, combined with three vinyl silicone oils with different vinyl contents and positions, can achieve controllable tear force on HC films. By changing the amount of silicone-modified borate ester component added, the tear force can be stabilized at 1-2 g / inch (Examples 1 and 2) and 2-4 g / inch (Examples 3 and 4). The peel force under room temperature time tracking and high temperature aging tracking shows almost no increase or decrease.

[0103] As can be seen from Examples 1, 2, 3, and 4, the silicone pressure-sensitive adhesive of the present invention exhibits a low degree of silicon transfer to the colorless transparent curable coating (HC) film, which is significantly lower than that of the kinetic friction U. d The upper limit of the index value (≤0.3) will not affect the smoothness of the HC membrane itself.

[0104] Comparative Examples 1 and 2 show that the conventional silicone pressure-sensitive adhesive tackifier (MQ resin) exhibits a higher degree of tear strength increase under both room temperature and high temperature aging conditions compared to the silicone-modified borate ester component presented in this paper. More importantly, its coefficient of dynamic friction is significantly higher than that of the conventional silicone pressure-sensitive adhesive tackifier (MQ resin). d The upper limit of the index value (≤0.3) directly affects the smoothness of the HC membrane.

[0105] As can be seen from Comparative Examples 3 and 4, when only two types of vinyl silicone oil are mixed to form a vinyl silicone oil component and borate n-butyl ester is used as a tackifying component, the degree of increase in tear strength during room temperature aging and high temperature aging is much higher than that of Examples 1, 2, 3, and 4.

[0106] Although the present invention has been described in detail through the preferred embodiments described above, it should be understood that the above description should not be considered as a limitation of the present invention. Those skilled in the art will understand that modifications or adjustments can be made to the present invention based on the teachings of this specification. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A silicone pressure-sensitive adhesive suitable for curable coating film protection, comprising, by weight, 100 parts of vinyl silicone oil, 6-12 parts of silicone-modified borate ester, 1.4-1.6 parts of crosslinking agent, 0.8-1.2 parts of anchoring agent, and 1.2-1.4 parts of catalyst; wherein the silicone-modified borate ester is obtained by reacting the following raw materials in a vacuum distillation reactor: 5-10 parts by weight of triallyl borate, 4-8 parts by weight of tri(methacrylate ethyl) borate and 5-9 parts by weight of tri(methacrylate ethyl) borate; 40-80 parts by weight of dimethylisopropylsilane. The vinyl silicone oil component is obtained by uniformly stirring the following raw materials in a reaction vessel: The composition comprises 40-60 parts by weight of vinyl silicone oil A, 15-25 parts by weight of vinyl silicone oil B, 20-40 parts by weight of vinyl silicone oil C, and 0.1-0.3 parts by weight of ethynylcyclohexanol; vinyl silicone oil A has a viscosity of 9000-11000 mPa·s and a vinyl content of 0.12-0.16 wt%; vinyl silicone oil B has a viscosity of 54000-66000 mPa·s and a vinyl content of 0.08-0.10 wt%; vinyl silicone oil C has a viscosity of 1000-1100 mPa·s and a vinyl content of 0.21-0.25 wt%. The crosslinking agent component is a hydrogen-based polysiloxane with a hydrogen content of 0.95-1.05%; the structure of the hydrogen-based polysiloxane serving as the crosslinking agent component is as follows: , where m is a natural number greater than or equal to 0 and less than 3, and n is a natural number greater than 0; The anchoring agent component is a hydrogen-based polysiloxane containing epoxy groups; its specific structure is as follows: In this system, R1 and R2 are alkyl or H, X is an epoxy group, and k and j are natural numbers, with 1≤k≤7 and 1≤j≤4.

2. The silicone pressure-sensitive adhesive as described in claim 1, characterized in that, The catalyst component is a platinum catalyst formed by coordination of platinum and divinyltetramethyldisiloxane, wherein the platinum content is 4000-6000 ppm.

3. A method for preparing an organosilicon pressure-sensitive adhesive suitable for curable coating film protection as described in claim 1 or 2, comprising the following steps: 1) Preparation of organosilicon-modified borate ester component: 5-10 parts by weight of triallyl borate, 4-8 parts by weight of tri(methacrylate ethyl) borate and 5-9 parts by weight of tri(methacrylate ethyl) borate are added to a vacuum distillation reactor, stirred evenly, and then 40-80 parts by weight of dimethyl isopropylsilane are added and stirred to obtain organosilicon-modified borate ester component. The stirring temperature in step 1) is 80-120℃ and the stirring time is 4-6 hours. 2) Preparation of vinyl silicone oil component: 40-60 parts by weight of vinyl silicone oil A, 15-25 parts by weight of vinyl silicone oil B, 20-40 parts by weight of vinyl silicone oil C and 0.1-0.3 parts by weight of ethynylcyclohexanol are added sequentially to a reaction vessel and stirred at room temperature to obtain the vinyl silicone oil component. 3) Preparation of pressure-sensitive adhesive: Add 100 parts of vinyl silicone oil component to 120 parts of ethyl acetate and stir for 9-12 minutes. Then, while stirring, add 6-12 parts of organosilicon-modified borate ester component, 1.4-1.6 parts of crosslinking agent component, and 0.8-1.2 parts of anchoring agent component. Stir for 10 minutes. Finally, add 1.2-1.4 parts of catalyst component. After all the components are added, stir to obtain the final pressure-sensitive adhesive bath solution. 4) Curing of pressure-sensitive adhesive: The prepared bath solution is applied to the PET film and then placed in an oven for curing to obtain an organosilicon pressure-sensitive adhesive film suitable for hardened coating film protection.

4. The preparation method according to claim 3, characterized in that, In step 2), the stirring time at room temperature is 4-6 hours; and / or, in step 3), the stirring time is 14-16 minutes; and / or, in step 4), the oven temperature is 145-155℃ and the curing time is 1.5-2 minutes.

5. The application of the silicone pressure-sensitive adhesive for curable coating film protection as described in any one of claims 1-2, or the silicone pressure-sensitive adhesive for curable coating film protection prepared by the preparation method as described in any one of claims 3-4, in the field of electronic protective films.

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