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

Abstract

The application discloses a preparation method and application of low-hydroxyl methyl MQ silicone resin, and comprises the following steps: step S10, mixing and reacting silicate, end-capping agent, catalyst, water, organic solvent and alcohol to obtain an MQ silicone resin first solution; step S20, mixing and reacting the MQ silicone resin first solution with acid and water to obtain an MQ silicone resin second solution; step S30, washing the MQ silicone resin second solution with water, and then removing water to obtain an MQ silicone resin third solution; and step S40, adding silazane into the MQ silicone resin third solution, removing organic solvent and residual silazane after reaction, and obtaining the low-hydroxyl methyl MQ silicone resin. The method is hydrolyzed and capped twice, improves the capping efficiency, and maximally reduces alkoxy and hydroxyl on the resin. In addition, a small amount of silazane is used to treat the resin solution at the end, the hydroxyl is treated, the residual acid in the resin solution is neutralized, and the influence of the residual acid on the peeling force of the pressure-sensitive adhesive is reduced.

Description

Technical Field

[0001] This invention belongs to the field of silicone resin technology, and more specifically, relates to a method for synthesizing a methyl MQ silicone resin with low hydroxyl content, and the application of the methyl MQ silicone resin prepared by this synthesis method. Background Technology

[0002] MQ silicone resin is a type of silicone resin composed of monofunctional siloxane units (M units, with the structure R3SiO). 1 / 2 ) and tetrafunctional siloxane repeating units (Q units, with a structure of SiO) 4 / 2 It is an organosilicon resin formed through co-hydrolysis and condensation. Its unique double-layer spherical structure (inorganic silicon-oxygen core + organosilicon shell) endows it with excellent high and low temperature resistance, weather resistance, reinforcement, low dielectric and optical properties.

[0003] The higher the silanol content, the worse the aging resistance. Reducing the hydroxyl content of MQ resin has always been a hot research topic in the industry. Current methods for synthesizing methyl MQ silicone resin mainly include the silicate ester method and the sodium silicate method. The silicate ester method has a higher cost, but the resulting silicone resin has a controllable M / Q value and a narrow molecular weight distribution. The sodium silicate method has a certain cost advantage, but the resulting silicone resin has a wider molecular weight distribution, a higher hydroxyl content on the surface, and poorer reinforcing performance.

[0004] Chinese patent CN117777446A discloses a method for treating hydroxyl groups, which uses a high-hydroxyl silicone resin to react under acidic conditions to reduce the hydroxyl content of silanol groups. This method can reduce the hydroxyl content from about 5% to below 0.5%. However, this method uses a large amount of solvent and acid, and subsequent steps (salt washing, alkali washing, water washing, drying, etc.) are required to remove the solvent and acid. The process is relatively complex, generates a large amount of wastewater, and has high subsequent treatment costs.

[0005] Chinese patent CN108219137A provides a method for using trimethylchlorosilane to cap residual silanol groups in organosilicon resin. This process generates hydrogen chloride, the system is strongly acidic, and the post-processing is relatively complicated. Summary of the Invention

[0006] The main objective of this invention is to propose a method for preparing and applying methyl MQ silicone resin with low hydroxyl content, aiming to solve the technical problem of how to minimize the silanol content of MQ resin.

[0007] To achieve the above objectives, this invention proposes a method for preparing low-hydroxymethyl MQ silicone resin, comprising the following steps:

[0008] Step S10: Mix silicate ester, capping agent, catalyst, water, organic solvent and alcohol to react and obtain MQ silicone resin first solution;

[0009] Step S20: The first MQ silicone resin solution is mixed with acid and water to react and obtain the second MQ silicone resin solution;

[0010] Step S30: Wash the second MQ silicone resin solution with water until it is neutral, and then remove the water to obtain the third MQ silicone resin solution.

[0011] Step S40: Add silazane to the third solution of the MQ silicone resin, and after the reaction, remove the organic solvent and the remaining silazane to obtain low hydroxymethyl MQ silicone resin.

[0012] Optionally, in step S10, the mass ratio of silicate ester, capping agent, catalyst, water, organic solvent and alcohol is 100:(30~40):(40~60):(50~80):(40~60):(0.5~1).

[0013] Optionally, in step S10, the silicate ester is one or more of methyl orthosilicate, ethyl orthosilicate, Si28, and Si40.

[0014] Optionally, in step S10, the capping agent is one or more of hexamethyldisiloxane, trimethylmethoxysilane, and trimethylchlorosilane.

[0015] Optionally, in step S10, the catalyst is one or more of sulfuric acid, hydrochloric acid, and trifluoromethanesulfonic acid.

[0016] Optionally, in step S10, the organic solvent is selected from toluene, xylene, n-heptane, n-hexane, and 120# gasoline.

[0017] Optionally, in step S10, the alcohol is one or more of methanol, ethanol, propanol, and isopropanol.

[0018] Optionally, step S10 includes the following steps:

[0019] Step S11: First, mix the organic solvent, end-capping agent, water, catalyst, and alcohol, then add silicate ester dropwise, keep the temperature at 25~40℃, and stir for 20~40 minutes.

[0020] Step S12: Heat and maintain the temperature at 60~90℃, reflux for 2~4 hours;

[0021] Step S13: Cool down and let stand, then separate the water layer to obtain the first MQ silicone resin solution.

[0022] Optionally, in step S20, the mass ratio of the MQ silicone resin first solution, acid, and water is 100:2.7:1.2.

[0023] Optionally, in step S20, the acid is one or more of sulfuric acid, hydrochloric acid, propionic acid, and phosphoric acid.

[0024] Optionally, in step S20, the first solution of MQ silicone resin is mixed with acid and water and then stirred for 1 to 3 hours.

[0025] Optionally, in step S30, the mass ratio of the water used for washing to the second MQ silicone resin solution is 1:2.

[0026] Optionally, step S30 includes the following steps:

[0027] Step S31: Stir the second solution of MQ silicone resin and water for 20-40 minutes, then let it stand to separate the water layer;

[0028] Step S32: Heat up again to evaporate the remaining water, and obtain the third solution of MQ silicone resin.

[0029] Optionally, in step S40, the silazane is hexamethyldisilazane.

[0030] Optionally, in step S40, the mass ratio of the MQ silicone resin third solution to the silazane is 100:1.

[0031] Optionally, step S40 includes the following steps:

[0032] Step S41: Mix the MQ silicone resin third solution and silazane, then heat to 60~80℃ and maintain for 2~3 hours;

[0033] Step S42: Heat to 110℃-120℃ to evaporate silazane and organic solvent, and then cool down to obtain low hydroxyl methyl MQ resin.

[0034] The present invention also proposes the application of the above-mentioned low-hydroxyl methyl MQ silicone resin in the fields of silicone rubber reinforcement, pressure-sensitive adhesives and LED packaging materials.

[0035] This technical solution employs a two-stage hydrolysis sealing process, performing hydrolysis sealing twice to improve sealing efficiency and minimize alkoxy and hydroxyl groups on the resin. The prepared methylMQ silicone resin has a silanol content of less than 0.5%. Furthermore, this solution uses a small amount of silazane to treat the resin solution, neutralizing residual acid in the resin solution while treating the hydroxyl groups, thus reducing the impact of residual acid on the peel strength of the pressure-sensitive adhesive. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic flowchart of an embodiment of the low hydroxymethyl MQ silicone resin provided by the present invention.

[0038] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0040] It should be noted that, unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available products. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0041] Currently, methods for removing hydroxyl groups from methyl MQ silicone resin are quite complex and costly. For example, Chinese patent CN117777446A, after treating the hydroxyl groups, involves overly complicated steps for removing solvents and acids.

[0042] In view of this, the present invention provides a method for preparing a low-hydroxyl methyl MQ silicone resin, combined with... Figure 1 A schematic flowchart of an embodiment of the provided low-hydroxymethyl MQ silicone resin is shown, the method including the following steps.

[0043] Step S10: Mix silicate ester, capping agent, catalyst, water, organic solvent and alcohol to react and obtain MQ silicone resin first solution.

[0044] In the specific implementation, the organic solvent, end-capping agent, water, catalyst, and alcohol are first mixed, and then silicate ester is added dropwise. The temperature is maintained at 25~40℃, and the mixture is stirred for 20~40 minutes. The temperature is then raised and maintained at 60~90℃, and refluxed for 2~4 hours. After cooling and standing, the aqueous layer is separated to obtain the first MQ silicone resin solution. During the reaction, hydrolysis and end-capping occur simultaneously, initially removing silanol groups.

[0045] In some embodiments, the mass ratio of silicate ester, 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 preferred mass ratio of silicate ester, capping agent, catalyst, water, organic solvent, and alcohol is 100:30:40:50:50:0.5.

[0046] In some embodiments, the silicate ester is one or more selected from methyl orthosilicate, tetraethyl orthosilicate, Si28, and Si40. In this embodiment, methyl orthosilicate is preferred.

[0047] In some embodiments, the capping agent is one or more selected from hexamethyldisiloxane, trimethylmethoxysilane, and trimethylchlorosilane. In this embodiment, hexamethyldisiloxane is preferred.

[0048] In some embodiments, the catalyst is one or more selected from sulfuric acid, hydrochloric acid, and trifluoromethanesulfonic acid. In this embodiment, hydrochloric acid is preferred. More preferably, the concentration of hydrochloric acid, i.e., its mass fraction, is 31%.

[0049] 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 selected from methanol, ethanol, propanol, and isopropanol. In this embodiment, isopropanol is preferred.

[0050] Step S20: Mix the first MQ silicone resin solution with acid and water to obtain the second MQ silicone resin solution.

[0051] In practice, the first solution of MQ silicone resin is mixed with acid and water and stirred for 1 to 3 hours.

[0052] 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 selected from sulfuric acid, hydrochloric acid, propionic acid, and phosphoric acid. In this embodiment, hydrochloric acid is preferred. More preferably, the concentration of hydrochloric acid, i.e., the mass fraction, is 31%. During the reaction, hydrolysis and end-capping are performed again to further remove silanol groups.

[0053] Step S30: Wash the second MQ silicone resin solution with water and then remove the water to obtain the third MQ silicone resin solution.

[0054] In practice, the second MQ silicone resin solution and water are stirred for 20-40 minutes, then allowed to stand to separate the aqueous layer; the remaining water is then evaporated by heating to obtain the third MQ silicone resin solution. In this step, the acid remaining after the reaction is partially removed through layering.

[0055] In some embodiments, the mass ratio of water used for washing to the second MQ silicone resin solution is 1:2.

[0056] Step S40: Add silazane to the third solution of MQ silicone resin. After the reaction, remove the organic solvent and the remaining silazane to obtain low hydroxymethyl MQ silicone resin.

[0057] In specific implementation, the third solution of MQ silicone resin and silazane are mixed and heated to 60-80°C, maintained for 2-3 hours; then the temperature is raised to 110-120°C to evaporate the silazane and part of the organic solvent. After cooling, a low-hydroxyl methyl MQ silicone resin solution is obtained. In this embodiment, the preferred reaction temperature is 70°C, the reaction time is 3 hours, and the evaporation is carried out at atmospheric pressure at a temperature of 110°C. During the reaction, the silazane replaces the hydroxyl group, and the generated ammonia can neutralize the residual acid in the resin solution.

[0058] In some embodiments, the silazane is hexamethyldisilazane; the mass ratio of the MQ silicone resin third solution to the silazane is preferably 100:(1~2).

[0059] In the technical solution of this invention, a two-stage hydrolysis end-capping method is adopted, with end-capping performed after two separate hydrolysis processes. This improves the 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, neutralizing residual acid in the resin solution while treating the hydroxyl groups, thus reducing the impact of residual acid on the peel force of the pressure-sensitive adhesive.

[0060] This invention also proposes an application of the low-hydroxymethyl MQ silicone resin prepared above in the fields of silicone rubber reinforcement, pressure-sensitive adhesives, and LED packaging materials.

[0061] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0062] Example 1

[0063] In a three-necked flask, add 30g hexamethyldisilazane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropanol. After stirring, add 100g tetraethyl orthosilicate dropwise. Maintain the temperature at 30℃ and stir for 30min. Reflux for 3h, then cool and allow to separate into layers. Separate the acidic aqueous layer. Add 2.9g 31% hydrochloric acid and 1.3g water, stir for 1h, then add 50g water and stir for 30min. Allow to separate into layers. Separate the aqueous layer and heat to evaporate the water. After evaporating to dryness, cool to 50℃, add 1g hexamethyldisilazane, heat to 70℃, maintain for 3h, then heat to 110℃ to evaporate some toluene and silazane. After cooling, obtain a methylMQ silicone resin solution. Measure the molecular weight and silanol content of the sample. Example 2

[0064] In a three-necked flask, add 30g hexamethyldisilazane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropanol. After stirring, add 100g tetraethyl orthosilicate dropwise. Maintain the temperature at 30℃ and stir for 30min. Reflux for 4h, then cool and allow to separate into layers. Separate the acidic aqueous layer. Add 2.9g 31% hydrochloric acid and 1.3g water, stir for 1h, then add 50g water and stir for 30min. Allow to separate into layers. Separate the aqueous layer and heat to evaporate the water. After evaporating to dryness, cool to 50℃, add 1g hexamethyldisilazane, heat to 70℃, maintain for 3h, then heat to 110℃ to evaporate some toluene and silazane. After cooling, obtain a methylsiloxane MQ silicone resin solution. Measure the molecular weight and silanol content of the sample. Example 3

[0065] In a three-necked flask, add 30g hexamethyldisilazane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropanol. After stirring, add 100g tetraethyl orthosilicate dropwise. Maintain the temperature at 25℃ and stir for 30 minutes. Reflux for 3 hours, then cool and allow to separate into layers. Separate the acidic aqueous layer. Add 2.9g 31% hydrochloric acid and 1.3g water, stir for 1 hour, then add 50g water and stir for 30 minutes. Allow to separate into layers. Separate the aqueous layer and heat to evaporate the water. After evaporating to dryness, cool to 50℃, add 1g hexamethyldisilazane, heat to 70℃, maintain this temperature for 3 hours, then heat to 110℃ to evaporate some toluene and silazane. After cooling, obtain a methylMQ silicone resin solution. Measure the molecular weight and silanol content of the sample. Example 4

[0066] In a three-necked flask, add 30g hexamethyldisilazane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropanol. After stirring, add 100g tetraethyl orthosilicate dropwise. Maintain the temperature at 30℃ and stir for 30min. Reflux for 3h, then cool and allow to separate into layers. Separate the acidic aqueous layer. Add 2.9g 31% hydrochloric acid and 1.3g water, stir for 1h, then add 50g water and stir for 30min. Allow to separate into layers. Separate the aqueous layer and heat to evaporate the water. After evaporating to dryness, cool to 50℃, add 1g hexamethyldisilazane, heat to 50℃, maintain for 3h, then heat to 110℃ to evaporate some toluene and silazane. After cooling, obtain a methylMQ silicone resin solution. Measure the molecular weight and silanol content of the sample. Example 5

[0067] In a three-necked flask, add 30g hexamethyldisilazane, 80g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropanol. After stirring, add 100g tetraethyl orthosilicate dropwise. Maintain the temperature at 30℃ and stir for 30min. Reflux for 3h, then cool and allow to separate into layers. Separate the acidic aqueous layer. Add 2.9g 31% hydrochloric acid and 1.3g water, stir for 1h, then add 50g water and stir for 30min. Allow to separate into layers. Separate the aqueous layer and heat to evaporate the water. After evaporating to dryness, cool to 50℃, add 1g hexamethyldisilazane, heat to 70℃, maintain for 3h, then heat to 110℃ to evaporate some toluene and silazane. After cooling, obtain a methylMQ silicone resin solution. Measure the molecular weight and silanol content of the sample. Example 6

[0068] In a three-necked flask, add 20g hexamethyldisilazane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropanol. After stirring, add 100g tetraethyl orthosilicate dropwise. Maintain the temperature at 30℃ and stir for 30min. Reflux for 3h, then cool and allow to separate into layers. Separate the acidic aqueous layer. Add 2.9g 31% hydrochloric acid and 1.3g water, stir for 1h, then add 50g water and stir for 30min. Allow to separate into layers. Separate the aqueous layer and heat to evaporate the water. After evaporating to dryness, cool to 50℃, add 1g hexamethyldisilazane, heat to 70℃, maintain for 3h, then heat to 110℃ to evaporate some toluene and silazane. Cool to obtain a methylMQ silicone resin solution. Measure the molecular weight and silanol content of the sample. Example 7

[0069] Add 30g hexamethyldisiloxane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropanol to a three-necked flask. After stirring, add 100g methyl orthosilicate dropwise. Maintain the temperature at 30℃, stir for 30 minutes, and then reflux for 3 hours. Hydrolysis is rapid, and gelation occurs during the reaction. Comparative Example 1

[0070] Add 30g hexamethyldisiloxane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropanol to a three-necked flask. After stirring, add 100g tetraethyl orthosilicate dropwise. Maintain the temperature at 30℃ and stir for 30 minutes. Then, reflux for 3 hours. After cooling, allow the mixture to stand and separate into layers. Separate the acidic aqueous layer. Add 50g water and stir for 30 minutes. Allow the mixture to stand and separate into layers. Separate the aqueous layer and evaporate the water. After cooling, obtain a methyl MQ resin solution. Measure the molecular weight and silanol content of the sample. Comparative Example 2

[0071] In a three-necked flask, add 30g hexamethyldisiloxane, 40g 31% hydrochloric acid, 50g water, 50g toluene, and 0.5g isopropanol. After stirring, add 100g tetraethyl orthosilicate dropwise. Maintain the temperature at 30℃ and stir for 30 minutes. Then, reflux for 3 hours and allow to stand to separate the layers. Separate the acidic aqueous layer, add 50g water, stir for 30 minutes, and allow to stand to separate the layers. Separate the aqueous layer, heat to evaporate the water, and after drying, cool to 50℃. Add 1g hexamethyldisiloxane, heat to 70℃, maintain this temperature for 3 hours, and then heat to 110℃ to evaporate some toluene and silazane. After cooling, obtain a methyl MQ resin solution. Measure the molecular weight and silanol content of the sample.

[0072] [Performance Evaluation]

[0073] The molecular weight and hydroxyl content of Examples 1-6 and Comparative Examples 1-2 were determined respectively.

[0074] The molecular weight determination method in the examples was performed using gel permeation chromatography (GPC) with toluene as the mobile phase.

[0075] The method for testing the silanol content in the examples is: lithium aluminum hydride (LiAlH4) reaction-gas chromatography.

[0076] The results are shown in Table 1.

[0077] Table 1

[0078]

[0079] As can be seen from Table 1, the silanol content of the low-hydroxyl methyl MQ resin solutions prepared in Examples 1 and 2 is less than 0.5%. Compared with Examples 1 and 2, the dehydroxylation effect of the single hydrolysis end-capping and the single hydrolysis two-times end-capping in Comparative Examples 1 and 2 is not as good as that of the two-times hydrolysis end-capping.

[0080] Compared to Examples 1 and 2, the reaction temperature of the first hydrolysis sealing in Example 3 was lower, but the removal effect of silanol groups was worse.

[0081] Compared to Examples 1 and 2, the reaction temperature for secondary capping in Example 4 was lower, but the removal effect of silanol groups was worse.

[0082] Compared to Examples 1 and 2, the catalyst content in the first hydrolysis end-capping of Example 5 was too high, resulting in an excessively large molecular weight of the methyl MQ silicone resin obtained from the reaction and a poorer removal effect of silanol groups.

[0083] Compared to Examples 1 and 2, Example 6 reduced the amount of reactant siloxane added, resulting in an excessively large molecular weight of the methyl MQ silicone resin obtained from the reaction, and a poorer removal effect of silanol groups.

[0084] Pressure-sensitive adhesive peel force test

[0085] Take 110g each of Examples 1-6 and Comparative Examples 1-2, 44.3g of vinyl raw rubber, 200g of reagent-grade toluene, and 0.25g of ethynylcyclohexanol. Stir evenly and heat to remove moisture from the toluene to obtain pressure-sensitive adhesive component A samples 1-9.

[0086] Component A of the pressure-sensitive adhesive (1-8) was mixed with component B of the same batch (containing 0.5-0.6% silane, 0.2g of anchoring agent, and 0.2g of platinum catalyst with a content of 5000ppm) at a mass ratio of 30:1 to prepare pressure-sensitive adhesive samples 1-8. The performance of the pressure-sensitive adhesive was tested by coating.

[0087] Pressure-sensitive adhesive sample preparation and testing methods:

[0088] Sample preparation: The mixed pressure-sensitive adhesive sample is evenly coated onto the corona-treated PET film using a 25-micron coating rod, baked in a 150℃ oven for 2 minutes, and then cut into tape and attached to the steel plate.

[0089] Test: The peel force of the pressure-sensitive adhesive was tested using a tensile testing machine. The test results are shown in Table 2.

[0090] Table 2

[0091]

[0092] As can be seen from Table 2, the peel strength of the pressure-sensitive adhesive prepared from the low-hydroxyl methyl MQ resin solutions in Examples 1 and 2 is significantly improved.

[0093] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0094] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a low-hydroxymethyl MQ silicone resin, characterized in that, Includes the following steps: Step S10: Mix silicate ester, capping agent, catalyst, water, organic solvent and alcohol to react, and separate the aqueous layer to obtain the first solution of MQ silicone resin; Step S20: The first MQ silicone resin solution is mixed with acid and water to react and obtain the second MQ silicone resin solution; Step S30: Wash the second MQ silicone resin solution with water and then remove the water to obtain the third MQ silicone resin solution; Step S40: Add silazane to the third solution of MQ silicone resin, and after the reaction, remove the organic solvent and the remaining silazane to obtain low hydroxymethyl MQ silicone resin. In step S10, 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); the silicate ester is one or more of tetraethyl orthosilicate, Si28, and Si40; the end-capping agent is one or more of hexamethyldisiloxane, trimethylmethoxysilane, and trimethylchlorosilane; the catalyst is a 31% hydrochloric acid solution; 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, and propanol. In step S20, the acid is 31% hydrochloric acid; In step S40, the silazane is hexamethyldisilazane; Step S10 includes the following steps: Step S11: First, mix the organic solvent, end-capping agent, water, catalyst, and alcohol, then add silicate ester dropwise, keep the temperature at 30~40℃, and stir for 20~40 minutes. Step S12: Heat and maintain the temperature at 60~90℃, reflux for 2~4 hours; Step S13: Cool down and let stand, then separate the water layer to obtain the first MQ silicone resin solution; In step S20, the mass ratio of the MQ silicone resin first solution, acid, and water is 100:2.7:1.

2. Step S40 includes the following steps: Step S41: Mix the MQ silicone resin third solution and silazane, then heat to 60~80℃ and maintain for 2~3 hours; Step S42: Heat to 110℃~120℃ to evaporate silazane and organic solvent, and then cool down to obtain low hydroxyl methyl MQ resin.

2. The method for preparing a low-hydroxymethyl MQ silicone resin according to claim 1, characterized in that, Step S30 includes the following steps: Step S31: Stir the second solution of MQ silicone resin and water for 20-40 minutes, then let it stand to separate the water layer; Step S32: Heat up again to evaporate the remaining water, and obtain the third solution of MQ silicone resin.

3. The application of the low-hydroxymethyl MQ silicone resin prepared by the method of any one of claims 1-2 in the fields of silicone rubber reinforcement, pressure-sensitive adhesives and LED packaging materials.

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