High temperature resistant silicone pressure sensitive adhesive and method of synthesis thereof

Abstract

The application provides a high-temperature-resistant organic silicon pressure-sensitive adhesive and a synthesis method thereof, and belongs to the technical field of organic silicon.The method comprises the following steps: taking octamethylcyclotetrasiloxane, octaphenylcyclotetrasiloxane and methylvinylcyclosiloxane as raw materials, generating linear polymethylphenylvinylsiloxane through ring-opening copolymerization of the ring body, and preparing a high-molecular-weight phenyl raw rubber; taking phenyltrimethoxysilane or phenyltriethoxysilane as raw material, preparing a hydroxyl-containing phenyl silicone resin prepolymer through hydrolysis reaction and limited polycondensation; after the high-molecular-weight phenyl raw rubber is dissolved by a solvent, the hydroxyl-containing phenyl silicone resin prepolymer is added and dissolved by heating, and a catalyst is added and reacted, an organic silicon pressure-sensitive adhesive is prepared. Through the synergistic effect of the high-molecular-weight phenyl raw rubber and the phenyl in the resin, the final pressure-sensitive adhesive product can still maintain good structural stability in a high-temperature environment.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon technology, and specifically relates to high-temperature resistant organosilicon pressure-sensitive adhesives and their synthesis methods. Background Technology

[0002] Silicone pressure-sensitive adhesives, as a special type of pressure-sensitive adhesive material, are primarily composed of a silicon-oxygen bond backbone consisting entirely of alternating silicon and oxygen atoms, belonging to the polyorganosiloxane family. Silicone pressure-sensitive adhesives offer advantages such as good adhesion to both high-energy and low-energy surfaces, high temperature resistance, non-corrosiveness, and non-irritation. However, the heat resistance limit of conventional silicone pressure-sensitive adhesives is generally around 200℃, maintaining good performance with no residue and no delamination. In reality, the actual operating temperatures in the electronics industry and aerospace are 280℃-300℃, and in certain scenarios, exceed 300℃. When the temperature exceeds the temperature resistance limit of the silicone pressure-sensitive adhesive, some methyl siloxane bonds undergo thermal degradation, destroying the original cross-linked network structure. The small molecular fragments produced by degradation migrate to the surface, forming residue. Long-term high-temperature aging can also lead to interface failure, resulting in the peeling off of some adhesive layers.

[0003] Therefore, further improving the temperature resistance limit of silicone pressure-sensitive adhesives has great market value. Summary of the Invention

[0004] In view of this, the present invention provides a high-temperature resistant silicone pressure-sensitive adhesive and a method for synthesizing the same, aiming to solve at least one technical problem in the prior art.

[0005] This invention is implemented as follows: The first aspect of this invention provides a method for synthesizing a high-temperature resistant silicone pressure-sensitive adhesive, the method comprising the following steps: S1. Using octamethylcyclotetrasiloxane, octaphenylcyclotetrasiloxane, and methylvinylcyclosiloxane as raw materials, linear polymethylphenylvinylsiloxane is generated through cyclic ring-opening copolymerization to obtain high molecular weight phenyl raw rubber. S2. Using phenyltrimethoxysilane or phenyltriethoxysilane as raw materials, a hydroxyl-containing phenyl silicone resin prepolymer is prepared through hydrolysis and limited polycondensation. S3. The high molecular weight phenyl raw rubber is dissolved in a solvent, and then the hydroxyl-containing phenyl silicone resin prepolymer is added and heated to dissolve. A catalyst is added to react and obtain an organosilicon pressure-sensitive adhesive.

[0006] Furthermore, the synthesis method further includes: S4. Add inorganic filler to the silicone pressure-sensitive adhesive prepared in S3 and mix thoroughly; The inorganic filler is at least one of glass powder, heat-resistant aluminum powder, zirconium oxide, cerium oxide, boron nitride, and iron oxide. The amount of the inorganic filler is 0.5wt%-3wt% of the silicone pressure-sensitive adhesive.

[0007] Furthermore, the step of preparing high molecular weight phenyl raw gum in S1 specifically includes: S11. Prepare raw materials methylcyclotetrasiloxane, octaphenylcyclotetrasiloxane and methylvinylcyclosiloxane with a phenyl content of 5 mol%-15 mol% and a vinyl content of 0.01 mol%-0.05 mol% to obtain a mixed cyclic body; S12, the mixed ring is dehydrated and impurities are removed under vacuum or N2 protection at 55℃-95℃ to remove moisture and low-boiling substances. S13. Add end-capping agent and alkaline catalyst, and react at 90℃-160℃ for 5h-10h in N2 atmosphere to achieve cyclic ring-opening copolymerization to generate linear polymethylphenyl vinylsiloxane; S14. Increase the temperature to 140℃-160℃ to allow the alkaline catalyst to decompose on its own, or add an acidic neutralizing agent to terminate the reaction. S15, 140℃-200℃, vacuum (≤10 mmHg) to remove unreacted monomers and low-cyclic compounds until no distillate is obtained, yielding high molecular weight phenyl raw gum.

[0008] Further, the alkaline catalyst is tetramethylammonium hydroxide or KOH; its dosage is 0.01wt%-5wt% of the mixed rings. The capping agent is hexamethyldisiloxane, and its dosage is 0.02wt%-2wt% of the mixed ring.

[0009] Furthermore, the steps for preparing the hydroxyphenyl silicone resin prepolymer in S2 include: S21, phenyltrimethoxysilane or phenyltriethoxysilane combined with methyltrimethoxysilane to obtain a mixed raw material; S22. In an inert solvent or solvent-free system, deionized water is slowly added dropwise to the mixed raw materials at 0℃-10℃ under neutral or weakly acidic conditions to carry out the hydrolysis reaction; S23. After the hydrolysis reaction is completed, the system is heated to 40℃-60℃ and a limited polycondensation reaction is carried out for 2h-6h. S24. After the limited polycondensation reaction is completed, the product is washed with water until neutral and the solvent is removed by vacuum distillation to obtain a hydroxyphenyl silicone resin prepolymer.

[0010] Furthermore, the inert solvent is at least one of toluene and isopropanol.

[0011] Furthermore, the molar ratio of the deionized water to the hydrolyzed groups in the mixed raw materials is 1.0-1.2:1.

[0012] Furthermore, in S3, the mass ratio of high molecular weight phenyl raw gum to hydroxyphenyl silicone resin prepolymer is 1:1-15; the heating and dissolution temperature is 50℃-90℃.

[0013] Furthermore, the catalyst in S3 is tetramethylammonium hydroxide, KOH, NaOH, hydrochloric acid, or ethylenediamine; The catalyst dosage is 0.01%-0.1% of the total mass of high molecular weight phenyl raw gum and hydroxyl phenyl silicone resin prepolymer.

[0014] Furthermore, the reaction temperature in S3 is 50℃-110℃, and the reaction time is 3h-10h.

[0015] The second aspect of this invention is a high-temperature resistant organosilicon pressure-sensitive adhesive, which is prepared by the above-described synthesis method. Compared with the prior art, the present invention has the following beneficial effects: 1. This invention introduces phenyl and vinyl groups into the polysiloxane backbone, utilizing the phenyl group to impart higher thermal stability to the molecule, effectively improving the heat resistance of the silicone pressure-sensitive adhesive; using octaphenylcyclotetrasiloxane as a comonomer to participate in ring-opening copolymerization, the phenyl structural unit is directly introduced into the raw rubber molecular backbone; at the same time, the hydroxyl-containing phenyl silicone resin prepolymer prepared by this invention further introduces a rigid phenyl structure into the system; the synergistic effect of the phenyl groups in the raw rubber and resin enables the final pressure-sensitive adhesive product to maintain good structural stability under high temperature conditions.

[0016] 2. The silicone pressure-sensitive adhesive prepared by this invention can withstand high temperatures above 300°C, effectively overcoming the problem of traditional methyl silicone pressure-sensitive adhesives experiencing a sharp increase in crosslinking degree and adhesive failure due to the thermal decomposition of organic groups such as methyl silicone groups under high temperature conditions.

[0017] 3. This invention utilizes the polycondensation reaction of a hydroxyl-containing phenyl silicone resin prepolymer and a high-molecular-weight phenyl raw rubber to form a suitable cross-linked network structure. The polar silanol groups in the phenyl silicone resin endow the pressure-sensitive adhesive with good wetting ability and initial tack, while the high-molecular-weight phenyl raw rubber provides the necessary cohesive force. The synergistic effect of both results in the silicone pressure-sensitive adhesive prepared by this invention exhibiting excellent peel strength and holding power, while maintaining stable peel strength at high temperatures, thus avoiding problems such as residual adhesive and white mist precipitation after high-temperature baking. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] A method for synthesizing high-temperature resistant silicone pressure-sensitive adhesive, comprising the following steps: S1. Using octamethylcyclotetrasiloxane, octaphenylcyclotetrasiloxane, and methylvinylcyclosiloxane as raw materials, linear polymethylphenylvinylsiloxane is generated through cyclic ring-opening copolymerization to obtain high molecular weight phenyl raw rubber.

[0020] S1 specifically includes S11-S15: S11, Raw material ratio; High-purity octamethylcyclotetrasiloxane (D4) and octaphenylcyclotetrasiloxane (D4) ph ), methyl vinyl cyclosiloxanes (such as D4) vi Using 1,000 raw materials, homogeneous mixing yields a mixed ring; Specifically, the target phenyl content of the mixed ring is set at 5 mol%-40 mol% (preferably 5 mol%-15 mol%), and the vinyl content is set at 0.01 mol%-1.0 mol% (preferably 0.01 mol%-0.05 mol%), with the above molar contents based on silicon atoms (Si).

[0021] S12, Dehydration and impurity removal; The mixed rings are dehydrated and impurities are removed under vacuum or N2 protection at 55℃-95℃ (preferably 70℃-80℃) to remove trace amounts of water and low-boiling substances, thereby preventing side reactions. S13, ring-opening polymerization; By adding a capping agent and an alkaline catalyst, and reacting at 90℃-160℃ for 4h-10h in a N2 atmosphere, cyclic ring-opening copolymerization is achieved to generate linear polymethylphenyl vinylsiloxane. The alkaline catalyst is tetramethylammonium hydroxide (TMAH) or KOH, preferably TMAH, and the temperature is preferably 95℃-110℃, and the reaction time is preferably 4h-5h; its amount is 0.01wt%-5wt% of the mixed ring, preferably 0.02wt%-0.1wt%; the end-capping agent is hexamethyldisiloxane, and its amount is 0.02-2wt% of the mixed ring, preferably 0.05wt%-0.1wt%.

[0022] S14, Catalyst degradation; Heat to 140℃-160℃ and hold for 30min-60min to allow the alkaline catalyst to decompose on its own, or add an acidic neutralizing agent (such as phosphoric acid), stir thoroughly and check the pH until it is neutral, then terminate the reaction. S15, vacuum de-lowering molecules; Unreacted monomers and low-cyclic compounds are removed at 140℃-200℃ (preferably 160℃-180℃) under vacuum (≤10mmHg) until no distillate is obtained, yielding high molecular weight phenyl raw gum with a number average molecular weight range of 10. 5 Da-10 6 Da.

[0023] S2. Using phenyltrimethoxysilane or phenyltriethoxysilane as raw materials, a hydroxyl-containing phenyl silicone resin prepolymer is prepared through hydrolysis and limited polycondensation.

[0024] S2 specifically includes S21-S24: S21, Raw material ratio; Phenylacetyltrimethoxysilane or phenyltriethoxysilane is combined with methyltrimethoxysilane to obtain a mixed raw material; avoid using difunctional monomers (such as Ph2SiO2) to prevent premature crosslinking.

[0025] S22, hydrolysis reaction; In an inert solvent (such as toluene or isopropanol) or solvent-free system, deionized water is slowly added dropwise to the mixed raw materials at 0℃-10℃ under neutral or weakly acidic conditions to carry out the hydrolysis reaction. Weakly acidic conditions refer to adding a small amount of acetic acid to control the pH of the system to 4.5-6.5, in order to avoid local over-hydrolysis that could lead to gelation.

[0026] The molar ratio of deionized water to hydrolyzable groups in the mixed raw materials is 1.0-1.2:1; the hydrolyzable groups refer to alkoxy groups attached to silicon atoms, specifically ethoxy and / or methoxy groups in this invention.

[0027] S23, Polycondensation control; After the hydrolysis reaction is complete, the system is heated to 40℃-60℃ for a limited polycondensation reaction for 2-6 hours; no strong alkali or high temperature is applied to retain -SiOH. The reaction is then terminated by removing low-boiling substances and monitoring viscosity / hydroxyl value.

[0028] S24, Post-processing; After the limited polycondensation reaction is completed, the product is washed with water until neutral and the solvent is removed by vacuum distillation to obtain a hydroxyl-containing phenyl silicone resin prepolymer with a solid content of 50%-70%, a hydroxyl residue of about 0.5wt%-2wt%, a molecular weight of 3000-4000, and a phenyl content of 3wt%-30wt%. It needs to be stored in a sealed, light-proof container to prevent self-polymerization.

[0029] S3. The high molecular weight phenyl raw rubber is dissolved in a solvent, and then the hydroxyl-containing phenyl silicone resin prepolymer is added and heated to dissolve. A catalyst is added to react and obtain an organosilicon pressure-sensitive adhesive.

[0030] The mass ratio of high molecular weight phenyl raw gum to hydroxyphenyl silicone resin prepolymer is 1:1-15, preferably 1:1-2. The following examples illustrate a ratio of 1:1.5. The heating and dissolution temperature is 50℃-90℃. The catalyst is tetramethylammonium hydroxide, KOH, NaOH, hydrochloric acid, or ethylenediamine. The catalyst dosage is 0.01%-0.1% of the total mass of the high molecular weight phenyl raw gum and hydroxyphenyl silicone resin prepolymer. The following examples illustrate 0.1% tetramethylammonium hydroxide or hydrochloric acid. The reaction temperature is 50℃-110℃, and the reaction time is 3h-10h. The following examples illustrate a reaction at 110℃ for 5h, using an azeotropic dehydration separator. The selection of parameters and materials in the above conditions is not limited to the examples described below; other selections within the same range are also applicable. In specific implementation, in order to further improve the high temperature resistance of the silicone pressure-sensitive adhesive, the synthesis method of the present invention further includes S4: adding an inorganic filler to the silicone pressure-sensitive adhesive obtained in S3 and mixing it evenly; the inorganic filler is at least one of glass powder, heat-resistant aluminum powder, zirconium oxide, cerium oxide, boron nitride, and iron tetroxide; the amount of inorganic filler is 0.5wt%-3wt% of the silicone pressure-sensitive adhesive, and the following example uses 1wt% glass powder, but it is not limited to this, and other values ​​and inorganic fillers within the range are applicable.

[0031] Example 1 This embodiment describes a method for synthesizing a high-temperature resistant silicone pressure-sensitive adhesive, which includes the following steps: S1. Weigh 876.3g of octamethylcyclotetrasiloxane (D4, 2.954mol) and 123.4g of octaphenylcyclotetrasiloxane (D4). ph 0.156 mol), 0.3 g methylvinylcyclosiloxane (D4) vi 0.870 mmol) was homogeneously mixed to obtain a mixed cyclic compound; under N2 protection, it was heated to 80℃ and held for about 30 min to remove trace amounts of moisture and low-boiling substances; 0.5 g of alkaline catalyst tetramethylammonium hydroxide and 1 g of end-capping agent hexamethyldisiloxane were added, and the temperature was raised to 100℃ for ring-opening polymerization for 5 h; after the reaction was completed, the temperature was raised to 140℃ and held for 40 min to decompose the tetramethylammonium hydroxide and terminate the reaction; the temperature was raised to 170℃ and unreacted monomers and low-cyclic compounds were removed under a vacuum of ≤10 mmHg. The removal endpoint was determined by monitoring the content of acyclic compounds in the distillate by gas chromatography, and high molecular weight phenyl raw gum was obtained.

[0032] S2. Weigh 200g of phenyltrimethoxysilane (1.009mol) and 40g of methyltrimethoxysilane (0.294mol) to obtain a mixed raw material; add 400g of isopropanol and adjust the pH of the system to 5 with acetic acid. Under low temperature conditions (about 5℃), slowly add about 90g of deionized water dropwise while stirring to carry out the hydrolysis reaction; after the addition is complete, raise the temperature to 50℃ and keep it at that temperature for 4h for a limited polycondensation reaction; after the limited polycondensation reaction is completed, wash the product with water until neutral, remove the solvent isopropanol by vacuum distillation to obtain a hydroxyphenyl silicone resin prepolymer, and store it in a sealed, light-protected container.

[0033] S3. Weigh 100g of high molecular weight phenyl raw gum and 150g of hydroxyl phenyl silicone resin prepolymer. First, add the high molecular weight phenyl raw gum to toluene and dissolve the raw gum into a 10% solution. Then add the hydroxyl phenyl silicone resin prepolymer and heat to 70℃. After stirring evenly, add 0.25g of tetramethylammonium hydroxide and heat to 110℃ for 5 hours. Use a water separator to remove water through azeotropic distillation. After the reaction is complete, wash the product with water until neutral and remove the solvent by vacuum distillation to obtain the organosilicon pressure-sensitive adhesive.

[0034] Example 2 This embodiment describes a method for synthesizing a high-temperature resistant silicone pressure-sensitive adhesive, which includes the following steps: S1. Weigh 876.3g of octamethylcyclotetrasiloxane (D4) and 123.4g of octaphenylcyclotetrasiloxane (D4). ph ), 0.3g methylvinylcyclosiloxane (D4) vi The homogeneous mixture was used to obtain a mixed cyclic compound; the mixture was slowly evacuated and heated to 80°C, and held for about 30 minutes to remove trace amounts of moisture and low-boiling substances; 0.5 g of alkaline catalyst tetramethylammonium hydroxide and 1 g of end-capping agent hexamethyldisiloxane were added, and the mixture was heated to 100°C for ring-opening polymerization for 4 hours; after the reaction was completed, the mixture was heated to 140°C and held for 40 minutes to decompose the tetramethylammonium hydroxide and terminate the reaction; the mixture was heated to 170°C and removed unreacted monomers and low-cyclic compounds under a vacuum of ≤10 mmHg. The removal endpoint was determined by monitoring the content of acyclic compounds in the distillate using gas chromatography, thus obtaining high molecular weight phenyl raw gum.

[0035] S2. Weigh 200g of phenyltriethoxysilane (0.832mol) and 30g of methyltrimethoxysilane (0.220mol) to obtain a mixed raw material; add acetic acid to adjust the pH of the system to 5, and slowly add about 57g of deionized water dropwise while stirring under low temperature conditions (about 5℃) without other solvents to carry out the hydrolysis reaction; after the addition is complete, raise the temperature to 50℃ and keep it at that temperature for 4h for a limited polycondensation reaction; after the limited polycondensation reaction is completed, wash the product with water until neutral, remove the solvent by vacuum distillation to obtain a hydroxyphenyl silicone resin prepolymer, and store it in a sealed container away from light.

[0036] S3. Weigh 100g of high molecular weight phenyl raw gum and 150g of hydroxyl phenyl silicone resin prepolymer. First, add the high molecular weight phenyl raw gum to toluene and dissolve the raw gum into a 10% solution. Then add the hydroxyl phenyl silicone resin prepolymer and heat to 70℃. After stirring evenly, add 0.25g of hydrochloric acid and heat to 110℃ for 5 hours. Use a water separator to remove water through azeotropic distillation. After the reaction is complete, wash the product with water until neutral and remove the solvent by vacuum distillation to obtain the organosilicon pressure-sensitive adhesive.

[0037] Example 3 This embodiment describes a method for synthesizing a high-temperature resistant silicone pressure-sensitive adhesive, which includes the following steps: S1. Weigh 876.3g of octamethylcyclotetrasiloxane (D4) and 123.4g of octaphenylcyclotetrasiloxane (D4). ph ), 0.3g methylvinylcyclosiloxane (D4) vi The homogeneous mixture was used to obtain a mixed cyclic compound; nitrogen gas was applied and the mixture was heated to 80°C and held for about 30 minutes to remove trace amounts of moisture and low-boiling substances; 0.5 g of alkaline catalyst tetramethylammonium hydroxide and 1 g of end-capping agent hexamethyldisiloxane were added, and the mixture was heated to 100°C for a ring-opening polymerization reaction for 4 hours; after the reaction was completed, the mixture was heated to 140°C and held for 40 minutes to decompose the tetramethylammonium hydroxide and terminate the reaction; the mixture was heated to 170°C and unreacted monomers and low-cyclic compounds were removed under a vacuum of ≤10 mmHg. The removal endpoint was determined by monitoring the content of acyclic compounds in the distillate using gas chromatography, thus obtaining high molecular weight phenyl raw gum.

[0038] S2. Weigh 100g of phenyltrimethoxysilane (0.504mol), 100g of phenyltriethoxysilane (0.416mol), and 35g of methyltrimethoxysilane (0.257mol) to obtain a mixed raw material. Under low temperature conditions (approximately 5°C) without other solvents, slowly add approximately 64g of deionized water dropwise while stirring to carry out a hydrolysis reaction. After the addition is complete, raise the temperature to 50°C and maintain the temperature for a limited polycondensation reaction for 4 hours. After the limited polycondensation reaction is completed, wash the product with water until neutral, remove the solvent by vacuum distillation, and obtain a hydroxyl-containing phenyl silicone resin prepolymer, which is then sealed and stored in the dark.

[0039] S3. Weigh 100g of high molecular weight phenyl raw gum and 150g of hydroxyl phenyl silicone resin prepolymer. First, add the high molecular weight phenyl raw gum to toluene and dissolve the raw gum into a 10% solution. Then add the hydroxyl phenyl silicone resin prepolymer and heat to 70℃. After stirring evenly, add 0.25g of hydrochloric acid and heat to 110℃ for 5 hours. Use a water separator to remove water through azeotropic distillation. After the reaction is complete, wash the product with water until neutral and remove the solvent by vacuum distillation to obtain the organosilicon pressure-sensitive adhesive.

[0040] Example 4 In this embodiment, 1 wt% of glass powder was added to the silicone pressure-sensitive adhesive prepared in Example 1.

[0041] Example 5 In this embodiment, 1 wt% of glass powder was added to the silicone pressure-sensitive adhesive prepared in Example 2.

[0042] Example 6 In this embodiment, 1 wt% of glass powder was added to the silicone pressure-sensitive adhesive prepared in Example 3.

[0043] Example 7 The difference between this embodiment and Example 1 is that the amount of octaphenylcyclotetrasiloxane in S1 is reduced to 90g (0.114mol), while the other conditions and steps are the same as in Example 1.

[0044] Example 8 The difference between this embodiment and Example 1 is that the amount of octaphenylcyclotetrasiloxane in S1 is increased to 200g (0.252mol), while the other conditions and steps are the same as in Example 1.

[0045] Example 9 The difference between this embodiment and Example 1 is that the amount of octaphenylcyclotetrasiloxane in S1 is increased to 300g (0.366mol), while the other conditions and steps are the same as in Example 1.

[0046] Comparative Example 1 This comparative example is a conventional silicone pressure-sensitive adhesive, which is mainly composed of silicone rubber (107 silicone rubber) and methyl MQ resin in a mass ratio of 1:1.5, and is combined with an organic solvent (toluene) to form a silicone pressure-sensitive adhesive with a solid content of 60%.

[0047] Comparative Example 2 The only difference between this comparative example and Example 1 is that the raw material octaphenylcyclotetrasiloxane in S1 is replaced with a mixed cyclic form of methylphenylsiloxane. All other conditions and steps are the same as in Example 1.

[0048] Comparative Example 3 The only difference between this comparative example and Example 1 is that methyltrimethoxysilane is not added in S2; all other conditions and steps are the same as in Example 1.

[0049] Comparative Example 4 The only difference between this comparative example and Example 1 is that the hydroxyphenyl silicone resin prepolymer is replaced with methyl MQ resin; all other conditions and steps are the same as in Example 1.

[0050] The silicone pressure-sensitive adhesives prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were made into pressure-sensitive tapes and their performance was tested. The test results are shown in Tables 1 and 2 below.

[0051] The test method for initial tack is in accordance with the national standard GB / T 4852-2002 "Test method for initial tack of pressure-sensitive adhesive tape (rolling ball method)".

[0052] The peel strength test method refers to the national standard GB / T 2792-2014 "Test Method for Peel Strength of Adhesive Tapes", with a peel angle of 180°. Three parallel samples were set for each group of samples, and the average value was taken.

[0053] High-temperature resistance test: A 40mm × 40mm piece of silicone pressure-sensitive adhesive to be tested was adhered to a standard 304 stainless steel test plate and then rolled back and forth three times at a speed of 120mm / s under the weight of a pressure roller. The steel plate with the adhesive tape was then placed on a hot plate with a gradient temperature (test temperature range 200℃-400℃, gradient temperature interval 10℃) for 30 minutes. After cooling to room temperature, the plate was peeled off, and the amount of adhesive residue on the steel plate was recorded using a scanner. The temperature at which adhesive residue appeared was used as the characterization index for high-temperature resistance. Three parallel samples were set up for each group of samples, and the average value was taken.

[0054] High-temperature peel strength: After placing the silicone pressure-sensitive adhesive sample to be tested in an environment of 250℃ for 2 hours, the peel strength at 180° was tested. Three parallel samples were set up for each group of samples, and the average value was taken.

[0055] Table 1

[0056] Table 1 shows that the silicone pressure-sensitive material prepared in the embodiments of the present invention is basically no different from the conventional silicone material in Comparative Example 1 in terms of initial tack and room temperature peel strength. However, the high temperature resistance is significantly increased, and after long-term use at a high temperature of 250°C, the peel strength decreases by less than 15%, and in some embodiments, the decrease is even less than 3%.

[0057] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for synthesizing high-temperature resistant organosilicon pressure-sensitive adhesive, characterized in that, The synthesis method includes the following steps: S1. Using octamethylcyclotetrasiloxane, octaphenylcyclotetrasiloxane, and methylvinylcyclosiloxane as raw materials, linear polymethylphenylvinylsiloxane is generated through cyclic ring-opening copolymerization to obtain high molecular weight phenyl raw rubber. S2. Using phenyltrimethoxysilane or phenyltriethoxysilane as raw materials, a hydroxyl-containing phenyl silicone resin prepolymer is prepared through hydrolysis and limited polycondensation. S3. The high molecular weight phenyl raw rubber is dissolved in a solvent, and then the hydroxyl-containing phenyl silicone resin prepolymer is added and heated to dissolve. A catalyst is added to react and obtain an organosilicon pressure-sensitive adhesive.

2. The method for synthesizing the high-temperature resistant organosilicon pressure-sensitive adhesive according to claim 1, characterized in that, The synthesis method further includes: S4. Add inorganic filler to the silicone pressure-sensitive adhesive prepared in S3 and mix thoroughly; The inorganic filler is at least one of glass powder, heat-resistant aluminum powder, zirconium oxide, cerium oxide, boron nitride, and iron oxide. The amount of the inorganic filler is 0.5wt%-3wt% of the silicone pressure-sensitive adhesive.

3. The method for synthesizing the high-temperature resistant organosilicon pressure-sensitive adhesive according to claim 1, characterized in that, The specific steps in S1 for preparing high molecular weight phenyl raw gum include: S11. Prepare raw materials methylcyclotetrasiloxane, octaphenylcyclotetrasiloxane and methylvinylcyclosiloxane with a phenyl content of 5 mol%-15 mol% and a vinyl content of 0.01 mol%-0.05 mol% to obtain a mixed cyclic body; S12, the mixed ring is dehydrated and impurities are removed under vacuum or N2 protection at 55℃-95℃ to remove moisture and low-boiling substances. S13. Add end-capping agent and alkaline catalyst, and react at 90℃-160℃ for 5h-10h in N2 atmosphere to achieve cyclic ring-opening copolymerization to generate linear polymethylphenyl vinylsiloxane; S14. Increase the temperature to 140℃-160℃ to allow the alkaline catalyst to decompose on its own, or add an acidic neutralizing agent to terminate the reaction. S15, 140℃-200℃, vacuum (≤10 mmHg) to remove unreacted monomers and low-cyclic compounds until no distillate is obtained, yielding high molecular weight phenyl raw gum.

4. The method for synthesizing the high-temperature resistant organosilicon pressure-sensitive adhesive according to claim 3, characterized in that, The alkaline catalyst is tetramethylammonium hydroxide or KOH; its dosage is 0.01wt%-5wt% of the mixed rings. The capping agent is hexamethyldisiloxane, and its dosage is 0.02wt%-2wt% of the mixed ring.

5. The method for synthesizing the high-temperature resistant organosilicon pressure-sensitive adhesive according to claim 1, characterized in that, The step of preparing the hydroxyphenyl silicone resin prepolymer in step S2 includes: S21, phenyltrimethoxysilane or phenyltriethoxysilane combined with methyltrimethoxysilane to obtain a mixed raw material; S22. In an inert solvent or solvent-free system, deionized water is slowly added dropwise to the mixed raw materials at 0℃-10℃ under neutral or weakly acidic conditions to carry out the hydrolysis reaction; S23. After the hydrolysis reaction is completed, the system is heated to 40℃-60℃ and a limited polycondensation reaction is carried out for 2h-6h. S24. After the limited polycondensation reaction is completed, the product is washed with water until neutral and the solvent is removed by vacuum distillation to obtain a hydroxyphenyl silicone resin prepolymer.

6. The method for synthesizing the high-temperature resistant organosilicon pressure-sensitive adhesive according to claim 5, characterized in that, In S22, the inert solvent is at least one of toluene and isopropanol.

7. The method for synthesizing the high-temperature resistant organosilicon pressure-sensitive adhesive according to claim 5, characterized in that, In S22, the molar ratio of the deionized water to the hydrolyzable groups in the mixed raw materials is 1.0-1.2:

1.

8. The method for synthesizing the high-temperature resistant organosilicon pressure-sensitive adhesive according to claim 1, characterized in that, In S3, the mass ratio of high molecular weight phenyl raw gum to hydroxyphenyl silicone resin prepolymer is 1:1-15; the heating and dissolution temperature is 50℃-90℃; the reaction temperature is 50℃-110℃, and the reaction time is 3h-10h.

9. The method for synthesizing the high-temperature resistant organosilicon pressure-sensitive adhesive according to claim 1, characterized in that, The catalyst in S3 is tetramethylammonium hydroxide, KOH, NaOH, hydrochloric acid, or ethylenediamine; The catalyst dosage is 0.01%-0.1% of the total mass of high molecular weight phenyl raw gum and hydroxyl phenyl silicone resin prepolymer.

10. A high-temperature resistant silicone pressure-sensitive adhesive, characterized in that, It is prepared by the synthesis method of the high-temperature resistant organosilicon pressure-sensitive adhesive as described in any one of claims 1 to 9.

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