Preparation method and application of low-hydroxyl methyl MQ silicon resin

Abstract

The invention discloses a preparation method and application of low-hydroxyl methyl MQ silicon resin, and the preparation method comprises the following steps: step S10, mixing silicate ester, an end-capping reagent, a catalyst, water, an organic solvent and alcohol for reaction to obtain a first MQ silicon resin solution; step S20, mixing the first MQ silicon resin solution with acid and water for reaction to obtain a second MQ silicon resin solution; step S30, washing the second MQ silicon resin solution with water, and removing moisture to obtain a third MQ silicon resin solution; and step S40, adding silazane into the third solution of the MQ silicon resin, reacting, and removing the organic solvent and the residual silazane to obtain the low-hydroxyl methyl MQ silicon resin. According to the scheme, two times of hydrolysis blocking are respectively carried out, so that the blocking efficiency is improved, and alkoxy and hydroxyl on the resin are reduced to the maximum extent. Besides, in the scheme, a small amount of silazane is finally used for treating the resin solution, residual acid in the resin solution is neutralized while hydroxyl is treated, and the influence of the residual acid on the stripping force of the pressure-sensitive adhesive is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicone resins, and more particularly relates to a method for synthesizing a methyl MQ silicone resin with a low hydroxyl content, and applications of the methyl MQ silicone resin prepared by the synthesis method. Background Art

[0002] MQ silicone resin is a kind of silicone resin composed of monofunctional siloxane chain segments (M units, structure R3SiO 1 / 2 ) and tetrafunctional siloxane segments (Q units, structured as SiO 4 / 2 ) is a silicone resin formed by co-hydrolysis and polycondensation. Its unique double-layer spherical structure (inorganic silicon oxide core + silicone shell) gives it excellent high and low temperature resistance, weather resistance, reinforcement, low dielectric properties, and optical properties.

[0003] The higher the silanol content, the worse its aging resistance. Reducing the hydroxyl content of MQ resins has been a hot research topic in the industry. Existing methods for synthesizing methyl MQ silicone resins are primarily divided into silicate and sodium silicate methods. The silicate method is more expensive, but the resulting silicone resin has a controllable M / Q ratio and a narrow molecular weight distribution. The sodium silicate method offers certain cost advantages, but the resulting silicone resin has a wide molecular weight distribution, a higher surface hydroxyl content, and poorer reinforcement properties.

[0004] Chinese patent CN117777446A discloses a hydroxyl treatment method, which uses a high-hydroxyl silicone resin to react under acidic conditions to achieve the purpose of reducing the silicon hydroxyl group. It can reduce the hydroxyl group from about 5% to below 0.5%. However, this solution uses a large amount of solvents and acids, and subsequently requires a large number of steps (salt washing, alkali washing, water washing, drying, etc.) to remove the solvents and acids. The process is relatively complicated, and a large amount of wastewater is generated during the process, and the subsequent treatment cost is high.

[0005] Chinese patent CN108219137A provides a method for capping residual silanol groups in silicone resins using trimethylchlorosilane. This process produces hydrogen chloride, and the system is strongly acidic, making post-processing more complicated. Summary of the Invention

[0006] The main purpose of the present invention is to provide a preparation method and application of a methyl MQ silicone resin with a low hydroxyl content, aiming to solve the technical problem of how to minimize the silanol content of the MQ resin.

[0007] To achieve the above object, the present invention provides a method for preparing a low-hydroxymethyl MQ silicone resin, comprising the following steps: Step S10, mixing silicate, end-capping agent, catalyst, water, organic solvent and alcohol to react to obtain a first MQ silicone resin solution; Step S20, mixing the first MQ silicone resin solution with acid and water to obtain a second MQ silicone resin solution; Step S30, washing the second MQ silicone resin solution with water until it becomes neutral, and then removing water to obtain a third MQ silicone resin solution; Step S40: adding silazane to the third MQ silicone resin solution, removing the organic solvent and the remaining silazane after the reaction, and obtaining a low-hydroxymethyl MQ silicone resin.

[0008] Optionally, in step S10, the mass ratio of silicate, end-capping agent, catalyst, water, organic solvent and alcohol is 100: (30-40): (40-60): (50-80): (40-60): (0.5-1).

[0009] Optionally, in step S10, the silicate is one or more of methyl orthosilicate, ethyl orthosilicate, Si28, and Si40.

[0010] Optionally, in step S10, the capping agent is one or more of hexamethyldisiloxane, trimethylmethoxysilane, and trimethylchlorosilane.

[0011] Optionally, in step S10, the catalyst is one or more of sulfuric acid, hydrochloric acid, and trifluoromethanesulfonic acid.

[0012] Optionally, in step S10, the organic solvent is selected from toluene, xylene, n-heptane, n-hexane, and 120# gasoline.

[0013] Optionally, in step S10, the alcohol is one or more of methanol, ethanol, propanol, and isopropanol.

[0014] Optionally, step S10 includes the following steps: Step S11: first mix the organic solvent, end-capping agent, water, catalyst, and alcohol, then dropwise add silicate, maintain the temperature at 25-40° C., and stir for 20-40 minutes; Step S12: heating and maintaining the temperature at 60-90° C., and reflux for 2-4 hours; Step S13: cooling and standing, separating and removing the water layer to obtain a first MQ silicone resin solution.

[0015] Optionally, in step S20, the mass ratio of the first MQ silicone resin solution, acid, and water is 100:2.7:1.2.

[0016] Optionally, in step S20, the acid is one or more of sulfuric acid, hydrochloric acid, propionic acid, and phosphoric acid.

[0017] Optionally, in step S20, the first MQ silicone resin solution is mixed with acid and water, and stirred for reaction for 1 to 3 hours.

[0018] Optionally, in step S30, the mass ratio of the washing water to the second MQ silicone resin solution is 1:2.

[0019] Optionally, step S30 includes the following steps: Step S31, stirring the second MQ silicone resin solution and water for 20-40 minutes, and then allowing to stand to separate the water layer; Step S32: raising the temperature again to evaporate the remaining water to obtain a third MQ silicone resin solution.

[0020] Optionally, in step S40, the silazane is hexamethyldisilazane.

[0021] Optionally, in step S40, the mass ratio of the third MQ silicone resin solution to silazane is 100:1.

[0022] Optionally, step S40 includes the following steps: Step S41, mixing the third MQ silicone resin solution and silazane, heating the mixture to 60-80° C. and maintaining the temperature for 2-3 hours; Step S42: heating the temperature to 110° C.-120° C. to evaporate the silazane and the organic solvent, and then cooling the temperature to obtain the low-hydroxymethyl MQ resin.

[0023] The present invention also proposes an application of the low-hydroxy methyl MQ silicone resin in the fields of silicone rubber reinforcement, pressure-sensitive adhesive and LED packaging materials.

[0024] This technical solution utilizes a two-stage hydrolysis end-capping process, performing two separate hydrolysis end-capping steps. This improves end-capping efficiency and minimizes the number of alkoxy and hydroxyl groups on the resin, resulting in a methyl MQ silicone resin with a silanol content of less than 0.5%. Furthermore, this solution also uses a small amount of silazane to treat the resin solution at the end. This treatment neutralizes the residual acid in the resin solution while removing the hydroxyl groups, minimizing the impact of residual acid on the release strength of the pressure-sensitive adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is a schematic diagram of a process of an embodiment of the low-hydroxymethyl MQ silicone resin provided by the present invention.

[0027] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0028] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0029] It should be noted that, in the embodiments, those without specifying specific conditions, are carried out according to conventional conditions or the conditions recommended by the manufacturer. Those for reagents or instruments used that do not specify the manufacturer are conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes schemes A, B, or A and B that meet the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but must be based on those of ordinary skill in the art. When the combination of the technical solutions is contradictory or cannot be realized, it should be considered that the combination of such technical solutions does not exist and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work belong to the scope of protection of the present invention.

[0030] The current method for removing hydroxyl groups from methyl MQ silicone resin is relatively complicated and has a high processing cost. For example, after treating the hydroxyl groups in Chinese patent CN117777446A, the steps of removing the solvent and acid are too cumbersome.

[0031] In view of this, the present invention provides a method for preparing a low-hydroxy methyl MQ silicone resin, combined with Figure 1 A schematic flow chart of an embodiment of a low-hydroxymethyl MQ silicone resin is provided, and the method includes the following steps.

[0032] Step S10: mixing silicate, end-capping agent, catalyst, water, organic solvent and alcohol to react and obtain a first MQ silicone resin solution.

[0033] In a specific implementation, an organic solvent, end-capping agent, water, catalyst, and alcohol are first mixed, followed by the dropwise addition of silicate. The temperature is maintained at 25-40°C and stirred for 20-40 minutes. The temperature is then raised and maintained at 60-90°C, refluxed for 2-4 hours, and the mixture is cooled and allowed to stand. The aqueous layer is then separated to obtain the first MQ silicone resin solution. During the reaction, hydrolysis and end-capping proceed simultaneously, initially removing the silanol groups.

[0034] In some embodiments, the mass ratio of silicate ester, end-capping agent, catalyst, water, organic solvent, and alcohol is 100:(30-40):(40-60):(50-80):(40-60):(0.5-1). In this embodiment, the mass ratio of silicate ester, end-capping agent, catalyst, water, organic solvent, and alcohol is preferably 100:30:40:50:50:0.5.

[0035] In some embodiments, the silicate is one or more of methyl orthosilicate, ethyl orthosilicate, Si28, and Si40. In this embodiment, methyl orthosilicate is preferred.

[0036] In some embodiments, the end-capping agent is one or more of hexamethyldisiloxane, trimethylmethoxysilane, and trimethylchlorosilane. In this embodiment, hexamethyldisiloxane is preferred.

[0037] In some embodiments, the catalyst is one or more of sulfuric acid, hydrochloric acid, and trifluoromethanesulfonic acid. In this embodiment, hydrochloric acid is preferred. More preferably, the concentration of the hydrochloric acid, i.e., the mass fraction, is 31%.

[0038] In some embodiments, the organic solvent is selected from toluene, xylene, n-heptane, n-hexane, and 120# gasoline, preferably toluene. The alcohol is one or more of methanol, ethanol, propanol, and isopropanol. In this embodiment, isopropanol is preferred.

[0039] Step S20: mixing the first MQ silicone resin solution with acid and water to obtain a second MQ silicone resin solution.

[0040] In a specific implementation, the first MQ silicone resin solution is mixed with acid and water, and stirred to react for 1 to 3 hours.

[0041] In some embodiments, the mass ratio of the MQ silicone resin first solution, acid, and water is 100:2.7:1.2; the acid is one or more of sulfuric acid, hydrochloric acid, propionic acid, and phosphoric acid. In this embodiment, hydrochloric acid is preferred. More preferably, the concentration of the hydrochloric acid, i.e., the mass fraction, is 31%. During the reaction, hydrolysis and endcapping are further performed to further remove the silanol groups.

[0042] Step S30: Wash the second MQ silicone resin solution with water and then remove moisture to obtain a third MQ silicone resin solution.

[0043] In a specific implementation, the second MQ silicone resin solution and water are stirred for 20-40 minutes, then allowed to stand to separate the water layer; the temperature is then raised to evaporate the remaining water to obtain a third MQ silicone resin solution. In this step, the residual acid after the reaction is partially removed by separation.

[0044] In some embodiments, the mass ratio of the washing water to the second MQ silicone resin solution is 1:2.

[0045] Step S40: adding silazane to the third MQ silicone resin solution, removing the organic solvent and the remaining silazane after the reaction, and obtaining a low-hydroxymethyl MQ silicone resin.

[0046] In practice, the third MQ silicone resin solution and silazane are mixed and heated to 60-80°C for 2-3 hours. The temperature is then raised to 110-120°C to evaporate the silazane and some of the organic solvent. The temperature is then lowered to yield a low-hydroxyl methyl MQ silicone resin solution. In this embodiment, the preferred reaction temperature is 70°C and the reaction time is 3 hours. The evaporation is performed at atmospheric pressure and 110°C. During the reaction, the silazane replaces the hydroxyl groups, and the resulting ammonia neutralizes any residual acid in the resin solution.

[0047] In some embodiments, the silazane is hexamethyldisilazane; and the mass ratio of the third MQ silicone resin solution to the silazane is preferably 100:(1-2).

[0048] The technical solution of the present invention utilizes a two-stage hydrolysis end-capping process, with end-capping performed after each hydrolysis step. This improves end-capping efficiency and minimizes the presence of alkoxy and hydroxyl groups on the resin. This solution uses a small amount of silazane to treat the resin solution, treating the hydroxyl groups while simultaneously neutralizing the residual acid in the resin solution, thereby reducing the impact of residual acid on the release strength of the pressure-sensitive adhesive.

[0049] The present invention also proposes an application of the low-hydroxymethyl MQ silicone resin prepared above in the fields of silicone rubber reinforcement, pressure-sensitive adhesive and LED packaging materials.

[0050] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention. Example 1

[0051] To a three-necked flask, add 30g hexamethyldisiloxane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropyl alcohol. After stirring, add 100g of ethyl orthosilicate dropwise. Maintain the temperature at 30°C and stir for 30 minutes. Reflux the mixture for 3 hours, cool, and allow to separate. Separate the aqueous layer, add 2.9g of 31% hydrochloric acid and 1.3g of water, and stir for 1 hour. Add 50g of water, stir for 30 minutes, and allow to separate. After separating the aqueous layer, heat the mixture to evaporate the water. After evaporating to dryness, cool the mixture to 50°C, add 1g hexamethyldisilazane, heat the mixture to 70°C, and maintain the temperature for 3 hours. Heat the mixture to 110°C to evaporate some of the toluene and silazane, and cool the mixture to obtain a methyl MQ silicone resin solution. Measure the molecular weight and silanol content of the sample. Example 2

[0052] To a three-necked flask, add 30g hexamethyldisiloxane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropyl alcohol. After stirring, add 100g of ethyl orthosilicate dropwise. Maintain the temperature at 30°C and stir for 30 minutes. Reflux the mixture for 4 hours, cool, and allow to separate. Separate the acid-water layer, add 2.9g of 31% hydrochloric acid and 1.3g of water, and stir for 1 hour. Add 50g of water, stir for 30 minutes, and allow to separate. Separate the water layer, heat the mixture, evaporate the water, and then cool to 50°C. Add 1g hexamethyldisilazane, heat the mixture to 70°C, and maintain the temperature for 3 hours. Heat the mixture to 110°C to evaporate some of the toluene and silazane, and cool the mixture to obtain a methylsilicon MQ silicone resin solution. Measure the molecular weight and silanol content of the sample. Example 3

[0053] To a three-necked flask, add 30g hexamethyldisiloxane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropyl alcohol. After stirring, add 100g of ethyl orthosilicate dropwise. Maintain the temperature at 25°C and stir for 30 minutes. Then, heat the mixture to reflux for 3 hours. After cooling, allow the mixture to separate and stratify. Separate the aqueous layer, add 2.9g of 31% hydrochloric acid and 1.3g of water, and stir for 1 hour. Add 50g of water, stir for 30 minutes, and allow the mixture to separate and stratify. After separating the aqueous layer, heat the mixture to evaporate the water. After evaporating the water, cool the mixture to 50°C, add 1g hexamethyldisilazane, heat the mixture to 70°C, and maintain the temperature for 3 hours. Then, heat the mixture to 110°C to evaporate some of the toluene and silazane. Cool the mixture to obtain a methyl MQ silicone resin solution. Measure the molecular weight and silanol content of the sample. Example 4

[0054] To a three-necked flask, add 30g hexamethyldisiloxane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropyl alcohol. After stirring, add 100g of ethyl orthosilicate dropwise. Maintain the temperature at 30°C and stir for 30 minutes. Then, heat the mixture to reflux for 3 hours. After cooling, allow the mixture to separate and stratify. Separate the aqueous layer, add 2.9g of 31% hydrochloric acid and 1.3g of water, and stir for 1 hour. Add 50g of water, stir for 30 minutes, and allow the mixture to separate and stratify. After separating the aqueous layer, heat the mixture to evaporate the water. After evaporating to dryness, cool the mixture to 50°C, add 1g hexamethyldisilazane, heat the mixture to 50°C, and maintain the temperature for 3 hours. Then, heat the mixture to 110°C to evaporate some of the toluene and silazane. Cool the mixture to obtain a methyl MQ silicone resin solution. Measure the molecular weight and silanol content of the sample. Example 5

[0055] To a three-necked flask, add 30g hexamethyldisiloxane, 80g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropyl alcohol. After stirring, add 100g of ethyl orthosilicate dropwise. Maintain the temperature at 30°C and stir for 30 minutes. Reflux the mixture for 3 hours, cool, and allow to separate. Separate the aqueous layer, add 2.9g of 31% hydrochloric acid and 1.3g of water, and stir for 1 hour. Add 50g of water, stir for 30 minutes, and allow to separate. After separating the aqueous layer, heat the mixture to evaporate the water. After evaporating to dryness, cool the mixture to 50°C, add 1g hexamethyldisilazane, heat the mixture to 70°C, and maintain the temperature for 3 hours. Heat the mixture to 110°C to evaporate some of the toluene and silazane, and cool the mixture to obtain a methyl MQ silicone resin solution. Measure the molecular weight and silanol content of the sample. Example 6

[0056] To a three-necked flask, add 20g hexamethyldisiloxane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropyl alcohol. After stirring, add 100g of ethyl orthosilicate dropwise. Maintain the temperature at 30°C and stir for 30 minutes. Then, heat the mixture to reflux for 3 hours. After cooling, allow the mixture to separate and stratify. Separate the aqueous layer, add 2.9g of 31% hydrochloric acid and 1.3g of water, stir for 1 hour, then add 50g of water, stir for 30 minutes, and allow the mixture to separate. After separating the aqueous layer, heat the mixture to evaporate the water. After evaporating to dryness, cool the mixture to 50°C, add 1g hexamethyldisilazane, heat the mixture to 70°C, maintain the temperature for 3 hours, then heat the mixture to 110°C to evaporate some of the toluene and silazane. Cool the mixture to obtain a methyl MQ silicone resin solution. Measure the molecular weight and silanol content of the sample. Example 7

[0057] In a three-necked flask, add 30g of hexamethyldisiloxane, 40g of 31% hydrochloric acid, 50g of water, 50g of toluene, and 0.5g of isopropyl alcohol. After stirring, add 100g of methyl orthosilicate dropwise. Maintain the temperature at 30°C, stir for 30 minutes, and then reflux for 3 hours. Hydrolysis is rapid, and gelation occurs during the reaction. Comparative Example 1

[0058] To a three-necked flask, add 30g of hexamethyldisiloxane, 40g of 31% hydrochloric acid, 50g of water, 50g of toluene, and 0.5g of isopropyl alcohol. After stirring, add 100g of ethyl orthosilicate dropwise. Maintain the temperature at 30°C and stir for 30 minutes. Then, heat and reflux for 3 hours. After cooling, allow the mixture to separate into separate layers. Separate the acid-water layer, add 50g of water, stir for 30 minutes, and allow the mixture to separate into separate layers. After separating the water layer, heat the mixture and evaporate the water. After cooling, obtain a methyl MQ resin solution. Measure the sample's molecular weight and silanol content. Comparative Example 2

[0059] To a three-necked flask, add 30g hexamethyldisiloxane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropyl alcohol. After stirring, add 100g of ethyl orthosilicate dropwise. Maintain the temperature at 30°C and stir for 30 minutes. Reflux the mixture for 3 hours, cool, and allow to separate. Separate the acidic aqueous layer, add 50g of water, stir for 30 minutes, and allow to separate. After separating the aqueous layer, heat the mixture to evaporate the water. After evaporating the water, cool the mixture to 50°C, add 1g hexamethyldisilazane, heat the mixture to 70°C, maintain the temperature for 3 hours, then heat the mixture to 110°C to evaporate some of the toluene and silazane. Cool the mixture to obtain a methyl MQ resin solution. Measure the molecular weight and silanol content of the sample.

[0060]

Performance evaluation

[0061] The test method for the silanol content in the examples is lithium aluminum hydride (LiAlH 4 ) reaction-gas chromatography.

[0062] The results are shown in Table 1.

[0063] Table 1

[0064] As can be seen from Table 1, the silanol content of the low-hydroxy methyl MQ resin solutions prepared in Examples 1 and 2 is both lower than 0.5%. Compared with Examples 1 and 2, the dehydroxylation effect of the single hydrolysis end-capping and the double hydrolysis end-capping in Comparative Examples 1 and 2 is not as good as that of the double hydrolysis end-capping.

[0065] Compared with Examples 1 and 2, the reaction temperature of the first hydrolysis and end-capping in Example 3 was lower, but the removal effect of the silanol groups became worse.

[0066] Compared with Examples 1 and 2, the reaction temperature of the secondary end-capping in Example 4 is lowered, but the removal effect of the silanol groups is worsened.

[0067] Compared with Examples 1 and 2, the catalyst content of the first hydrolysis end-capping in Example 5 is too high, resulting in an excessively large molecular weight of the methyl MQ silicone resin obtained by the reaction and a poor removal effect of silanol groups.

[0068] Compared with Examples 1 and 2, Example 6 reduces the amount of siloxane added as a reactant, resulting in an excessively large molecular weight of the methyl MQ silicone resin obtained by the reaction and a poor removal effect of silanol groups. Pressure sensitive adhesive peel force test

[0069] Take 110g each of Examples 1-6 and Comparative Examples 1-2, 44.3g of vinyl rubber, 200g of reagent-grade toluene, and 0.25g of ethynylcyclohexanol, stir evenly, and heat to evaporate the water in the toluene to prepare pressure-sensitive adhesive component A samples 1-9.

[0070] Pressure-sensitive adhesive components A 1-8 were mixed evenly with component B from the same batch having a silicon-hydrogen content of 0.5-0.6, 0.2 g of an anchoring agent, and 0.2 g of a platinum catalyst with a content of 5000 ppm at a mass ratio of 30:1 to prepare pressure-sensitive adhesive samples 1-8, respectively. The pressure-sensitive adhesive properties were tested by coating.

[0071] Pressure sensitive adhesive sample preparation and testing methods: Sample preparation: The mixed pressure-sensitive adhesive sample was evenly coated on the corona-treated PET film using a 25-micron coating rod, baked in a 150°C oven for 2 minutes, and then cut into tapes and attached to the steel plate.

[0072] Test: Use a tensile testing machine to test the peeling force of the pressure-sensitive adhesive. The test results are shown in Table 2: Table 2

[0073] It can be seen from Table 2 that the peeling performance of the pressure-sensitive adhesive prepared from the low-hydroxyl methyl MQ resin solution prepared in Examples 1 and 2 is significantly improved.

[0074] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for preparing a low-hydroxymethyl MQ silicone resin, characterized in that: The following steps are involved: Step S10, mixing silicate, end-capping agent, catalyst, water, organic solvent and alcohol to react to obtain a first MQ silicone resin solution; Step S20, mixing the first MQ silicone resin solution with acid and water to obtain a second MQ silicone resin solution; Step S30, washing the second MQ silicone resin solution with water, and then removing water to obtain a third MQ silicone resin solution; Step S40: adding silazane to the third MQ silicone resin solution, removing the organic solvent and the remaining silazane after the reaction, and obtaining a low-hydroxymethyl MQ silicone resin.

2. The method for preparing a low-hydroxymethyl MQ silicone resin according to claim 1, wherein: In step S10, the mass ratio of silicate, end-capping agent, catalyst, water, organic solvent and alcohol is 100: (30-40): (40-60): (50-80): (40-60): (0.5-1).

3. The method for preparing a low-hydroxymethyl MQ silicone resin according to claim 1, wherein: In step S10, the silicate is one or more of methyl orthosilicate, ethyl orthosilicate, Si28, and Si40; the capping agent is one or more of hexamethyldisiloxane, trimethylmethoxysilane, and trimethylchlorosilane; the catalyst is one of sulfuric acid, hydrochloric acid, and trifluoromethanesulfonic acid; the organic solvent is selected from toluene, xylene, n-heptane, n-hexane, and 120# gasoline; and the alcohol is one or more of methanol, ethanol, propanol, and isopropanol.

4. The method for preparing a low-hydroxymethyl MQ silicone resin according to claim 1, wherein: The step S10 includes the following steps: Step S11: first mix the organic solvent, end-capping agent, water, catalyst, and alcohol, then dropwise add silicate, maintain the temperature at 25-40° C., and stir for 20-40 minutes; Step S12: heating and maintaining the temperature at 60-90° C., and reflux for 2-4 hours; Step S13: cooling and standing, separating and removing the water layer to obtain a first MQ silicone resin solution.

5. The method for preparing a low-hydroxymethyl MQ silicone resin according to claim 1, wherein: In the step S20, the mass ratio of the first MQ silicone resin solution, acid, and water is 100:2.7:1.

2.

6. The method for preparing a low-hydroxymethyl MQ silicone resin according to claim 1, wherein: In step S20, the acid is one or more of sulfuric acid, hydrochloric acid, propionic acid, and phosphoric acid.

7. The method for preparing a low-hydroxymethyl MQ silicone resin according to claim 1, characterized in that: The step S30 includes the following steps: Step S31, stirring the second MQ silicone resin solution and water for 20-40 minutes, and then allowing to stand to separate the water layer; Step S32: raising the temperature again to evaporate the remaining water to obtain a third MQ silicone resin solution.

8. The method for preparing a low-hydroxymethyl MQ silicone resin according to claim 1, wherein: In step S40, the silazane is hexamethyldisilazane.

9. The method for preparing a low-hydroxymethyl MQ silicone resin according to claim 1, characterized in that: The step S40 includes the following steps: Step S41, mixing the third MQ silicone resin solution and silazane, heating the mixture to 60-80° C. and maintaining the temperature for 2-3 hours; Step S42: heating the temperature to 110° C. to 120° C. to evaporate the silazane and the organic solvent, and then cooling the temperature to obtain the low-hydroxymethyl MQ resin.

10. Use of the low-hydroxymethyl MQ silicone resin prepared by the preparation method of the low-hydroxymethyl MQ silicone resin according to any one of claims 1 to 9 in the fields of silicone rubber reinforcement, pressure-sensitive adhesive and LED packaging materials.

Images