Composition and application of anti-aging silicone pressure sensitive adhesive

Abstract

The application discloses a kind of composition and application of ageing-resistant organic silicon pressure sensitive adhesive.The pressure sensitive adhesive includes: end vinyl raw rubber, methyl MQ resin, organic solvent, organic silicon linear polymer with vinyl functional group, organic silicon branched polymer with vinyl functional group, organic silicon monomer with vinyl functional group, hydrogen-containing silicone oil.The pressure sensitive adhesive can be applied in the application scene with the range of bonding force 0-100g / inch, the bonding force climbing rate of organic silicon pressure sensitive adhesive high temperature and high humidity ageing can reach ≤50%, the maximum crystal point size of film surface is not more than 100 μm, and 200 times magnification microscope observation 1cm×1cm adhesive film cut randomly, crystal point rate ≤1000 / m 2 .

Description

Technical Field

[0001] This invention belongs to the field of organosilicon, and particularly relates to the composition and application of an aging-resistant organosilicon pressure-sensitive adhesive. Background Technology

[0002] Silicone pressure-sensitive adhesives (PSAs) are widely used as protective films in process protection and shipping protection due to their advantages such as low curing temperature and no by-products. The curing mechanism of silicone platinum PSAs is a hydrosilylation reaction, where vinyl functional groups undergo an addition reaction with silicon-hydrogen bonds, curing to form a cross-linked network. Common silicone platinum PSA formulations are primarily linear polymers, resulting in a limited number of cross-linking points. The resulting silicone film exhibits good initial adhesion and high bonding strength, but the adhesion to the adhered object will decrease over time. Depending on the application scenario, different performance requirements exist for silicone PSAs, with some applications demanding a high rate of aging degradation. After process protection is completed, especially in electronic applications, excessively high adhesion degradation may damage the adhered object during the removal of the protective film, resulting in losses. Typically, silicone addition-type pressure-sensitive adhesive formulations involve mixing vinyl raw rubber, high-viscosity vinyl silicone oil, and MQ resin. The mixing of high molecular weight, high viscosity polysiloxane with MQ resin places very high demands on the dispersion capabilities of the equipment. In high-viscosity systems, insufficiently dissolved and dispersed resin and raw rubber can easily form "crystal points" after the film surface cures. The presence of crystal points can cause localized stress concentration and affect the light transmittance of the film surface. Therefore, silicone pressure-sensitive adhesive protective films used in the production process of 3C digital and other electronic products have high requirements for the presence of crystal points on the film surface.

[0003] CN 114958295 A discloses an ultra-low adhesion, low creepage silicone pressure-sensitive adhesive, its preparation method, and its application. The pressure-sensitive adhesive prepared by this invention is suitable for ultra-low adhesion applications, i.e., applications with an adhesion range of 0–3 g / inch. Currently, there are no technological inventions that solve the low creepage problem for applications with adhesion greater than 3 g / inch.

[0004] In summary, the application of addition-type silicone pressure-sensitive adhesives still faces challenges such as high adhesion creep rate and high crystal point rate on the film surface, which urgently need to be addressed. Summary of the Invention

[0005] To address the aforementioned technical problems, one objective of this invention is to provide an aging-resistant silicone pressure-sensitive adhesive. This adhesive exhibits an adhesion strength ramp-up rate of ≤50% under high-temperature and high-humidity aging in application scenarios with an adhesion strength range of 0–100 g / inch. Furthermore, the maximum crystal point size on the film surface does not exceed 100 μm, and under a 200x magnifying microscope, a randomly cut 1cm × 1cm film shows a crystal point rate of ≤1000 crystal points / m². 2 .

[0006] To achieve the above-mentioned objectives, this application adopts the following technical solution:

[0007] An aging-resistant silicone pressure-sensitive adhesive, the pressure-sensitive adhesive comprising the following components in parts by weight:

[0008]

[0009] The inventors discovered a structurally symmetrical branched vinyl silicone oil that can provide a denser and more regular cross-linked network for the system during curing, improving the modulus and adhesive stability of the film. Specifically, the vinyl content of this branched vinyl silicone oil needs to be within a specific range; exceeding this range will result in excessively high cross-linking density in the film, leading to decreased initial tack and lower adhesive strength, failing to meet the requirements of most application scenarios. While providing sufficient cross-linking functional groups, the Q-type branched vinyl silicone oil exhibits excellent compatibility with the raw rubber and resin in pressure-sensitive adhesives (PSAs), and has a low viscosity, only 200-600 cP at 25°C. Compared to the high-viscosity linear polysiloxanes used in traditional silicone PSAs, this allows for better dispersion of the PSA system, facilitating the full dissolution of the PSA composition in organic solvents, thereby significantly reducing the crystal size and crystal point rate of the film surface.

[0010] The aforementioned aging-resistant, low crystal point ratio silicone pressure-sensitive adhesive exhibits an adhesion strength ramp-up rate of ≤50% under high-temperature and high-humidity aging in application scenarios with an adhesion strength range of 0–100 g / inch. The maximum crystal point size on the film surface does not exceed 100 μm, and under a 200x magnifying microscope, a randomly cut 1cm × 1cm film shows a crystal point ratio of ≤1000 crystal points / m². 2 .

[0011] In one embodiment of this application, the terminal vinyl raw rubber has a molecular weight of 450,000 to 850,000, a volatile content of <1%, and a vinyl content of 0.03 to 0.06%.

[0012] In one embodiment of this application, the M / Q ratio of the MQ resin is 0.6 to 1.0, and the hydroxyl content is 0.1 to 1.5%.

[0013] In one embodiment of this application, the organic solvent is a nonpolar small molecule solvent, preferably one or more of hexamethyldisiloxane, ethyl acetate, benzene, toluene, and xylene.

[0014] In one embodiment of this application, the linear polymer silicone oil containing vinyl functional groups is a vinyl-terminated silicone oil, preferably with a viscosity of 10,000 to 100,000 cP at 25°C.

[0015] In one embodiment of this application, the general formula of the branched polymer containing vinyl functional groups is as follows:

[0016]

[0017] Wherein, n and t are each selected from a natural number from 1 to 200, and R1 and R2 are each selected from an aliphatic hydrocarbon group below C4 and an alicyclic group of C5-6, preferably each selected from methyl, ethyl, propyl, isopropyl, butyl, 3,3,3-trifluoropropyl, cyclopentyl, cyclohexyl, and phenyl; preferably, the vinyl content in the branched polymer containing vinyl functional groups is 0.1-1%; preferably, the viscosity of the branched polymer containing vinyl functional groups at 25°C is 20-600 cP.

[0018] In one embodiment of this application, the organosilicon monomer containing vinyl functional groups is a difunctional small molecule vinylsiloxane, preferably one or more of divinyldimethoxysilane, divinyldiethoxysilane, tetramethyldivinyldisiloxane, and divinylhexamethyltrisiloxane.

[0019] In one embodiment of this application, the hydrogen-containing silicone oil has a hydrogen content of 0.2-1.6% and a viscosity of 10-100 cP at 25°C.

[0020] Another object of the present invention is to provide a branched polymer containing vinyl functional groups.

[0021] A branched polymer containing vinyl functional groups, wherein the branched polymer is the same branched polymer used in the aforementioned pressure-sensitive adhesive, and the general structural formula of the branched polymer containing vinyl functional groups is as follows:

[0022]

[0023] Wherein, n and t are each selected from a natural number from 1 to 200, and R1 and R2 are each selected from an aliphatic hydrocarbon group below C4 and an alicyclic group of C5-6, preferably each selected from methyl, ethyl, propyl, isopropyl, butyl, 3,3,3-trifluoropropyl, cyclopentyl, cyclohexyl, and phenyl; preferably, the vinyl content in the branched polymer containing vinyl functional groups is 0.1-1%; preferably, the viscosity of the branched polymer containing vinyl functional groups at 25°C is 20-600 cP.

[0024] Another object of the present invention is to provide a method for preparing branched polymers containing vinyl functional groups.

[0025] A method for preparing a branched polymer containing vinyl functional groups, wherein the branched polymer is the branched polymer used in the pressure-sensitive adhesive described above, or is another branched polymer described above, the method comprising the following steps:

[0026] S1: Tetramethyl orthosilicate, hexamethyldisiloxane, and tetramethyldivinyldisiloxane are added to the reactor, heated, and hydrolyzed with water under an acid catalyst.

[0027] S2: Add a neutralizing agent to remove byproducts and obtain vinyl branched silicone oil end-capping agent;

[0028] S3: Add octamethylcyclotetrasiloxane, vinyl branched silicone oil end-capping agent, and acid catalyst to carry out an equilibrium reaction, and obtain branched silicone oil after the small molecules are removed.

[0029] In one embodiment of this application, the heating temperature in S1 is 40–120°C.

[0030] In one embodiment of this application, the acid catalyst in S1 is one or more of trifluoromethanesulfonic acid, concentrated sulfuric acid, and acetic acid.

[0031] In one embodiment of this application, the acid catalyst in S1 is an organic oxyacid, preferably one or more of trifluoromethanesulfonic acid, concentrated sulfuric acid, and acetic acid.

[0032] In one embodiment of this application, the neutralizing agent in S2 is an inorganic salt, preferably one or more of sodium bicarbonate, calcium carbonate, and sodium carbonate.

[0033] In one embodiment of this application, the acid catalyst in S3 is one or more of trifluoromethanesulfonic acid, concentrated sulfuric acid, and acetic acid. In one embodiment of this application, the reaction temperature in S3 is 40–120°C.

[0034] Another object of the present invention is to provide an application of an aging-resistant silicone pressure-sensitive adhesive.

[0035] An application of an aging-resistant silicone pressure-sensitive adhesive, wherein the pressure-sensitive adhesive is the pressure-sensitive adhesive described above, or is a branched polymer described above, or a branched polymer prepared by the method described above, and the pressure-sensitive adhesive is used in the fields of process protection films in industrial production processes and shipping protection films for electronic digital product screens.

[0036] Compared with the prior art, the positive effects of the present invention are as follows:

[0037] (1) In application scenarios with an adhesion range of 0 to 100 g / inch, the adhesion creep rate of silicone pressure-sensitive adhesive under high temperature and high humidity aging can reach ≤50%.

[0038] (2) The maximum crystal point size on the film surface does not exceed 100 μm, and the crystal point ratio of a randomly cut 1 cm × 1 cm film observed under a 200x magnifying microscope is ≤1000 crystal points / m. 2 . Attached Figure Description

[0039] Figure 1This is a microscopic observation image of the membrane surface in Example 1. Figure 2 This is a microscopic observation of the membrane surface in Comparative Example 1. Detailed Implementation

[0040] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0041] Other key raw materials used in the following embodiments of the present invention are as follows:

[0042] Vinyl end-capped raw rubber: Hesheng Silicon Industry, 110-0, molecular weight 450,000, vinyl content 0.06%, volatile matter <1%; Hesheng Silicon Industry, 110-0, molecular weight 650,000, vinyl content 0.04%, volatile matter <1%; Hesheng Silicon Industry, 110-0, molecular weight 850,000, vinyl content 0.03%, volatile matter <1%.

[0043] Vinyl-terminated silicone oil, Zhejiang Runhe; RH-Vi301, viscosity 100000cP, RH-Vi360, viscosity 60000cP, RH-Vi302, viscosity 20000cP, RH-Vi303, viscosity 10000cP.

[0044] Divinyldimethoxysilane, Quzhou Jiancheng, purity > 99%;

[0045] High-hydrogen-content silicone oil RH202-30, viscosity 30 cP, Zhejiang Runhe; Side-containing hydrogen-content silicone oil RH-H512, hydrogen content 1.2%, viscosity 60 cP; Side-containing hydrogen-content silicone oil RH-H510, hydrogen content 1.0%, viscosity 15 cP.

[0046] Tetramethyldivinyldisiloxane, Quzhou Jiancheng, purity > 99%;

[0047] Hexamethyldisiloxane, purity > 99%, Zhejiang Runhe;

[0048] Trifluoromethanesulfonic acid, Aladdin, purity > 99%;

[0049] Octamethylcyclotetrasiloxane, Hengyecheng, purity > 98%;

[0050] Methyl MQ resin xylene solution, Chenfei Technology CF 808;

[0051] Castel platinum catalyst, CAT-Pt050, Jiangsu Kexing New Materials Co., Ltd.

[0052] Branched vinyl silicone oil, DY-V411, Shandong Dayi.

[0053] Calcium carbonate, analytical grade, Maclean's;

[0054] Sodium bicarbonate, analytical grade, Maclean's;

[0055] Acetic acid, analytical grade, Maclean's.

[0056] The main testing methods involved in the following embodiments of the present invention are as follows:

[0057] (1) Pressure-sensitive adhesive adhesion test includes reference standard GB / T 2792-2014.

[0058] (2) Aging and heat resistance test method: According to the test method of GB / T 2792-2014, the pressure-sensitive tape was attached to the steel plate and placed in an oven with 60% humidity and 70℃ for 3 days to age. After taking it out and cooling it down, the adhesion was then tested.

[0059] (3) Randomly cut 20 1×1cm square pieces from a 210mm×297mm film sample, place them on a glass slide, and observe the crystal point size on the film surface under an optical microscope at 1000x magnification. Record the average number of crystal points as n, and calculate the crystal point rate (points / m). 2 ).

[0060] The model of the testing instrument is as follows:

[0061] Viscometer: Borelfeld RV, 21# rotor, 25℃, 100rpm;

[0062] Titrator: Mettler E38 automatic titrator;

[0063] Nuclear magnetic resonance imaging instrument: ASCEND 600M;

[0064] Adhesion strength: Kejian KJ-1065C tape peel strength tester;

[0065] Optical microscope: OLYMPUS CX23 biological microscope.

[0066] Preparation Example 1

[0067] Branched vinyl silicone oil is synthesized according to the following method:

[0068] 45.00 g of tetraethyl orthosilicate and 45.30 g of tetramethyldivinyldisiloxane were added to a three-necked flask and preheated to 60 °C under a nitrogen atmosphere. 85 μL of trifluoromethanesulfonic acid was added, and the mixture was stirred for 2 h. 9.01 g of deionized water was slowly added dropwise, and the reaction was continued for 3 h. 20.00 g of calcium carbonate was added to neutralize the trifluoromethanesulfonic acid, and the mixture was stirred for 1 h. After filtration, the mixture was distilled under reduced pressure at 60 °C and 10 mbar for 2 h to remove the byproduct ethanol and water, yielding a branched silicone oil end-capping agent 1 with a vinyl content of 22.8%.

[0069] 1288.02g of octamethylcyclotetrasiloxane, 50.05g of the above-mentioned branched silicone oil end-capping agent 1, and 1.54g of trifluoromethanesulfonic acid were added to the system. The reaction was continued at 55℃ for 6 hours. Then, 30.8g of calcium carbonate was added and the mixture was stirred for 1 hour. After filtration, small molecules were removed at 60℃ and 10mbar to obtain branched vinyl silicone oil A1311.31g. The vinyl content was determined to be 0.50% by chemical titration. In its structure, n=8, t=1, and R2 and R3 are methyl groups.

[0070] Product characterization:

[0071] Vinyl content: 0.50%, viscosity: 446 cP.

[0072] NMR data for 29Si (80MHz, CDCl3): [d,ppm] = -4.15CH2CH-Si(CH3)2-O-, -22.02(-Si(CH3)2-O-), -108.01(-Si-(O-Si-)4).

[0073] Preparation Example 2

[0074] 45.00 g of tetraethyl orthosilicate and 80.53 g of tetramethyldivinyldisiloxane were added to a three-necked flask and preheated to 100 °C under a nitrogen atmosphere. 0.5 g of acetic acid was added and the mixture was stirred for 2 h. 15.38 g of deionized water was slowly added dropwise and the reaction was continued for 3 h. 40.00 g of sodium bicarbonate was added to neutralize trifluoromethanesulfonic acid. After stirring for 1 h, the mixture was filtered and then distilled under reduced pressure at 60 °C and 10 mbar for 2 h to remove the byproduct ethanol and water, yielding a branched silicone oil end-capping agent 2 with a vinyl content of 11.7%.

[0075] 1248.95g of octamethylcyclotetrasiloxane, 67.25g of the above-mentioned branched silicone oil end-capping agent 2, and 1.52g of trifluoromethanesulfonic acid were added to the system. The reaction was continued at 55℃ for 6 hours. Then, 30.8g of calcium carbonate was added and the mixture was stirred for 1 hour. After filtration, small molecules were removed at 60℃ and 10mbar to obtain branched vinyl silicone oil B1289.88g. The vinyl content was determined to be 0.24% and the viscosity was 197cP by chemical titration. In its structure, n=1, t=150, and R2 and R3 are methyl groups.

[0076] Preparation Example 3

[0077] 1467.21g of octamethylcyclotetrasiloxane, 77.42g of branched silicone oil end-capping agent 1 from Preparation Example 1, and 1.78g of trifluoromethanesulfonic acid were added to a three-necked flask. The reaction was continued at 60°C for 10 hours to maintain equilibrium. Then, 44.50g of calcium carbonate was added and the mixture was stirred for another hour. After filtration, small molecules were removed at 100°C and 50mbar to obtain 13.73g of branched vinyl silicone oil C15. The vinyl content was determined to be 0.19% and the viscosity to be 540cp by chemical titration. In its structure, n=8, t=90, R2 is trifluoropropyl, and R3 is methyl.

[0078] Preparation Example 4

[0079] 850.03 g of octamethylcyclotetrasiloxane, 65.77 g of branched silicone oil end-capping agent 2 from Preparation Example 1, and 1.06 g of trifluoromethanesulfonic acid were added to a three-necked flask. The reaction was continued at 70 °C for 4 h to maintain equilibrium. Then, 31.80 g of calcium carbonate was added and the mixture was stirred for 1 h. After filtration, small molecules were removed at 80 °C and 10 mbar to obtain branched vinyl silicone oil D897.49 g. The vinyl content was determined to be 0.68% and the viscosity to be 35 cP by chemical titration. In its structure, n = 1, t = 20, and R2 and R3 are phenyl groups.

[0080] Example 1

[0081] Add 34.29g of CF 808MQ resin xylene solution and 28g of 110-0 methyl vinyl raw rubber with a molecular weight of 65w to the reactor, keep it at 40℃ and stir for 2h. Then add 33.48g of 2w viscosity end vinyl silicone oil RH-Vi302, 0.4g of divinyldimethoxysilane, 8.98g of branched vinyl silicone oil A with a vinyl content of 0.5%, and 0.33g of high hydrogen content silicone oil RH202-30 (hydrogen content of 1.6%) and continue stirring for 2h to obtain the pressure-sensitive adhesive product.

[0082] Add 30.71g xylene solvent and 0.18g CAT-Pt050, stir at room temperature for 1 hour, then coat the film (substrate: 38μm PET), cure at 150℃ for 2 minutes, resulting in a film thickness of 17μm. After 24 hours of bonding, the initial peel strength was measured to be 12.6g / inch. After aging in a 70℃, 60% RH oven for 3 days, the peel strength was measured to be 17.9g / inch, with an aging ramp-up rate of 42%. The calculated crystal point density was 500 / m². 2 .

[0083] Example 2

[0084] Add 50.68g of MQ resin CF 808 xylene solution and 50g of 110-0 methyl vinyl raw rubber with a molecular weight of 45w to the reactor, and keep it at 50℃ and stir for 2h. Then add 52.93g of 6w viscosity end vinyl silicone oil RH-Vi360, 1.63g of tetramethyldivinyldisiloxane, 27.69g of branched vinyl silicone oil B with a vinyl content of 0.24%, and 1.36g of side-hydrogen-containing silicone oil RH-H510 (hydrogen content of 1.0%), and continue stirring for 2h to obtain the pressure-sensitive adhesive product. After adding 54.29 g of ethyl acetate solvent and 0.39 g of CAT-Pt050 caster catalyst, the mixture was stirred at room temperature for 1 hour. A film was then coated (substrate: 50 μm PET) and cured at 150 °C for 2 minutes, resulting in a film thickness of 17 μm. The initial peel strength was measured at 13.7 g / inch after 24 hours of bonding. After aging in a 70 °C, 60% RH oven for 3 days, the peel strength was measured at 15.5 g / inch, with an aging ramp-up rate of 13%. The calculated crystal point density was 500 crystals / m². 2 .

[0085] Example 3

[0086] 77.96g of xylene solution of MQ resin CF-808 and 34g of 110-0 methyl vinyl raw rubber with a molecular weight of 85w were added to the reactor and stirred at 50°C for 2h. Then, 19.8g of 6w viscosity end vinyl silicone oil, 1.63g of dipyrethylenediethoxysilane, 33.94g of branched vinyl silicone oil D with a vinyl content of 0.68% and 1.13g of side-hydrogen-containing silicone oil (with a hydrogen content of 1.2%) were added and stirred for another 2h to obtain the pressure-sensitive adhesive product. Add 29.43g of hexamethyldisiloxane solvent and 0.28g of CAT-Pt050, stir at room temperature for 1 hour, then coat the film (substrate: 50μm PET), cure at 150℃ for 2 minutes, resulting in a film thickness of 17μm. After 24 hours of bonding, the initial peel strength was measured to be 15.1g / inch. After aging in a 70℃, 60% RH oven for 3 days, the peel strength was measured to be 22.3g / inch, with an aging ramp-up rate of 48%. The calculated crystal point ratio on the film surface was 1000 points / m. 2 .

[0087] Example 4

[0088] Add 98.60g of MQ resin xylene solution SH-5201S and 77g of 110-0 methyl vinyl raw rubber with a molecular weight of 65w to the reactor, keep it at 50℃ and stir for 2h. Then add 33.90g of 1w viscosity end vinyl silicone oil RH-Vi303, 4.84g of dipyrethylenediethoxysilane, 58.11g of branched vinyl silicone oil A with a vinyl content of 0.50%, and 1.94g of high hydrogen content silicone oil RH202-30 (hydrogen content 1.6%) and continue stirring for 2h to obtain the pressure-sensitive adhesive product. Add 50.73g xylene solvent and 0.49g CAT-Pt050, stir at room temperature for 1 hour, then coat the film (substrate: 50μm PET), cure at 150℃ for 2 minutes, resulting in a film thickness of 17μm. After 24 hours of bonding, the initial peel strength was measured to be 10.8g / inch. After aging in a 70℃, 60% RH oven for 3 days, the peel strength was measured to be 15.1g / inch, with an aging ramp-up rate of 40%. The calculated crystal point density was 500 / m². 2 .

[0089] Example 5

[0090] 195.71g of MQ resin SH-5201S xylene solution and 156g of 110-0 methyl vinyl raw rubber with a molecular weight of 65w were added to the reactor and stirred at 50℃ for 2h. Then, 116.22g of 1w viscosity-end vinyl silicone oil 1w-RH-Vi301, 3.87g of dipyrethylenediethoxysilane, 48.34g of branched vinyl silicone oil A with a vinyl content of 0.50% and 1.4g of high hydrogen content silicone oil RH202-30 (hydrogen content 1.6%) were added and stirred for another 2h to obtain the pressure-sensitive adhesive product. Add 41.29g xylene solvent and 0.93g CAT-Pt050, stir at room temperature for 1 hour, then coat the film (substrate: 50μm PET), cure at 150℃ for 2 minutes, resulting in a film thickness of 17μm. After 24 hours of bonding, the initial peel strength was measured to be 11.3g / inch. After aging in a 70℃, 60% RH oven for 3 days, the peel strength was measured to be 16.4g / inch, with an aging ramp-up rate of 45%. The calculated crystal point ratio on the film surface was 1000 points / m. 2 .

[0091] Example 6

[0092] 214.29g of xylene solution of MQ resin MSR8808 and 200g of 110-0 methyl vinyl raw rubber with a molecular weight of 65w were added to the reactor and stirred at 50℃ for 2h. Then, 133.07g of 10w viscosity end vinyl silicone oil RH-Vi301, 4.44g of dipyrethylenediethoxysilane, 55.35g of branched vinyl silicone oil A with a vinyl content of 0.50% and 1.61g of high hydrogen content silicone oil (hydrogen content of 1.6%) were added and stirred for another 2h to obtain the pressure-sensitive adhesive product. Add 35.71g xylene solvent and 1.09g CAT-Pt050, stir at room temperature for 1 hour, then coat the film (substrate: 50μm PET), cure at 150℃ for 2 minutes, resulting in a film thickness of 17μm. After 24 hours of bonding, the initial peel strength was measured to be 6.9g / inch. After aging in a 70℃, 60% RH oven for 3 days, the peel strength was measured to be 9.7g / inch, with an aging ramp-up rate of 41%. The calculated crystal point density was 500 / m². 2 .

[0093] Example 7

[0094] 285.71g of xylene solution of MQ resin MSR8808 and 189g of 110-0 methyl vinyl raw rubber with a molecular weight of 65w were added to the reactor and stirred at 40℃ for 2h. Then, 159.39g of 6w viscosity end vinyl silicone oil 6w-RH-Vi360, 1.16g of tetramethyldivinyldisiloxane, 70.46g of branched methyl vinyl silicone oil C with a vinyl content of 0.19% and 1.93g of side hydrogen-containing silicone oil RH-H512 with a hydrogen content of 1.2% were added and stirred for another 2h to obtain the pressure-sensitive adhesive product. Add 64.29g xylene solvent and 1.24g CAT-Pt050, stir at room temperature for 1 hour, then coat the film (substrate: 50μm PET), cure at 150℃ for 2 minutes, resulting in a film thickness of 17μm. After 24 hours of bonding, the initial peel strength was measured to be 12.6g / inch. After aging in a 70℃, 60% RH oven for 3 days, the peel strength was measured to be 18.3g / inch, with an aging ramp-up rate of 45%. The calculated crystal point density was 500 / m². 2 .

[0095] Comparative Example 1

[0096] Compared with Example 1, the only difference is that the branched polymer described in this invention was not added.

[0097] Add 34.29g of mqCF-808 resin xylene solution and 28g of 110-0 methyl vinyl raw rubber with a molecular weight of 65w to the reactor, keep it at 40℃ and stir for 2h. Then add 39.46g of 2w viscosity end vinyl silicone oil RH-Vi302, 0.4g of divinyldimethoxysilane and 0.33g of high hydrogen content silicone oil RH202-30 (hydrogen content 1.6%) and continue stirring for 2h to obtain the pressure-sensitive adhesive product. Add 30.71g xylene solvent and 0.18g CAT-Pt050, stir at room temperature for 1 hour, then coat the film (substrate: 38μm PET), cure at 150℃ for 2 minutes, resulting in a film thickness of 17μm. After 24 hours of bonding, the initial peel strength was measured to be 14.4g / inch. After aging in a 70℃, 60% RH oven for 3 days, the peel strength was measured to be 26.9g / inch, with an aging ramp-up rate of 87%. The calculated crystal point density was 9500 / m². 2 .

[0098] Comparative Example 2

[0099] Compared with Example 1, the only difference is that the branched polymer described in this invention was not added, but an equal mass of commercially available branched silicone oil DY-V411 was added.

[0100] Add 34.29g of xylene solution of MQ resin CF-808 and 28g of methyl vinyl raw rubber with a molecular weight of 65W to the reactor, and stir at 40℃ for 2h. Then add 33.48g of 2w viscosity end vinyl silicone oil RH-Vi302, 0.4g of dipyrethylenedimethoxysilane, 8.98g of branched vinyl silicone oil DY-V411, and 0.33g of high hydrogen content silicone oil RH202-30 (hydrogen content 1.6%), and continue stirring for 2h to obtain the pressure-sensitive adhesive product. After adding 30.71g of xylene solvent and CAT-Pt050, the mixture was stirred at room temperature for 1 hour, followed by coating (substrate: 38μm PET). The film was cured at 150℃ for 2 minutes, resulting in a film thickness of 17μm. The initial peel strength was measured at 15.1g / inch after 24 hours of bonding. After aging in a 70℃, 60% RH oven for 3 days, the peel strength was measured at 33.8g / inch, with an aging ramp-up rate of 124%. The calculated crystal point density was 6500 / m². 2 .

[0101]

[0102] As can be seen from Comparative Examples 1 and 2, the addition-type pressure-sensitive adhesive without the addition of the special structured branched vinyl silicone oil of this application showed increased aging creep and film surface crystal point rate. In Examples 1 to 6, the aging adhesion creep and film surface crystal point rate were significantly improved.

[0103] 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. An aging-resistant silicone pressure-sensitive adhesive, characterized in that, The pressure-sensitive adhesive comprises the following components in parts by weight: 15-35 parts of vinyl-terminated raw rubber, 15-45 parts of methyl MQ resin, 5-25 parts organic solvent 10-30 parts of an organosilicon linear polymer containing vinyl functional groups. 5-20 parts of organosilicon branched polymers containing vinyl functional groups 0.1 to 1.5 parts of organosilicon monomers containing vinyl functional groups, Hydrogen-containing silicone oil: 0.1~0.8 parts; The general structural formula of the organosilicon branched polymer containing vinyl functional groups is as follows: Wherein, n is one of the natural numbers from 1 to 8, t is one of the natural numbers from 1 to 200, and R1 and R2 are respectively selected as one of the aliphatic hydrocarbon groups below C4 and the alicyclic group of C5-6.

2. The pressure-sensitive adhesive according to claim 1, characterized in that, The terminated vinyl raw rubber has a molecular weight of 450,000 to 850,000, a volatile content of <1%, and a vinyl content of 0.03% to 0.06%. And / or, the methyl MQ resin has an M / Q ratio of 0.6 to 1.0 and a hydroxyl content of 0.1 to 1.5%; And / or, the organic solvent is a nonpolar small molecule solvent; And / or, the organosilicon linear polymer containing vinyl functional groups is a vinyl-terminated silicone oil.

3. The pressure-sensitive adhesive according to claim 2, characterized in that, The organic solvent is one or more selected from hexamethyldisiloxane, ethyl acetate, benzene, toluene, and xylene; And / or, the vinyl-functionalized organosilicon linear polymer has a viscosity of 10,000~100,000 cP at 25°C.

4. The pressure-sensitive adhesive according to claim 1, characterized in that, In the general formula of the organosilicon branched polymer containing vinyl functional groups, R1 and R2 are selected from one of methyl, ethyl, propyl, isopropyl, butyl, cyclopentyl, and cyclohexyl, respectively. The vinyl content in the organosilicon branched polymer containing vinyl functional groups is 0.1% to 1%. The viscosity of the organosilicon branched polymer containing vinyl functional groups is 20-600 cP at 25°C.

5. The pressure-sensitive adhesive according to claim 1, characterized in that, The organosilicon monomer containing vinyl functional groups is a difunctional small-molecule vinylsiloxane; And / or, the hydrogen content of the hydrogen-containing silicone oil is 0.2~1.6%, and the viscosity at 25°C is 10~100 cP.

6. The pressure-sensitive adhesive according to claim 5, characterized in that, The organosilicon monomer containing vinyl functional groups is one or more of divinyldimethoxysilane, divinyldiethoxysilane, tetramethyldivinyldisiloxane, and divinylhexamethyltrisiloxane.

7. A branched polymer containing vinyl functional groups, said branched polymer being the branched polymer used in the pressure-sensitive adhesive according to any one of claims 1-6, characterized in that, The general structural formula of the branched polymer containing vinyl functional groups is as follows: Wherein, n is one of the natural numbers from 1 to 8, t is one of the natural numbers from 1 to 200, and R1 and R2 are respectively selected as one of the aliphatic hydrocarbon groups below C4 and the alicyclic group of C5-6.

8. The branched polymer according to claim 7, characterized in that, In the general formula of the organosilicon branched polymer containing vinyl functional groups, R1 and R2 are selected from one of methyl, ethyl, propyl, isopropyl, butyl, cyclopentyl, and cyclohexyl, respectively. The vinyl content in the organosilicon branched polymer containing vinyl functional groups is 0.1% to 1%. The viscosity of the organosilicon branched polymer containing vinyl functional groups is 20-600 cP at 25°C.

9. A method for preparing a branched polymer containing vinyl functional groups, wherein the branched polymer is the branched polymer used in the pressure-sensitive adhesive according to any one of claims 1-6, characterized in that, The method includes the following steps: S1: Tetramethyldivinyldisiloxane tetraethyl orthosilicate is added to the reactor, heated, and hydrolyzed with water under acid catalyst. S2: Add a neutralizing agent to remove byproducts and obtain vinyl branched silicone oil end-capping agent; S3: Add octamethylcyclotetrasiloxane, vinyl branched silicone oil end-capping agent, and acid catalyst to carry out an equilibrium reaction, and obtain branched silicone oil after the small molecules are removed.

10. The method according to claim 9, characterized in that, The heating temperature in S1 is 40~120℃; And / or, the acid catalyst in S1 is an organic oxyacid; And / or, the neutralizing agent in S2 is an inorganic salt; And / or, the acid catalyst in S3 is an organic oxyacid; And / or, the reaction temperature in S3 is 40~120℃.

11. The method according to claim 10, characterized in that, The acid catalyst in S1 is one or more of trifluoromethanesulfonic acid and acetic acid; And / or, the neutralizing agent in S2 is one or more of sodium bicarbonate, calcium carbonate, and sodium carbonate; And / or, the acid catalyst in S3 is one or more of trifluoromethanesulfonic acid and acetic acid.

12. The use of an aging-resistant silicone pressure-sensitive adhesive, wherein the pressure-sensitive adhesive is any one of claims 1-6, or a branched polymer as described in claim 7 or 8, or a branched polymer prepared by any one of claims 9-11, and the pressure-sensitive adhesive is used in the fields of process protection films in industrial production processes and shipping protection films for electronic digital product screens.

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