Preparation method of methyl silicone resin for high-temperature mica plate

Abstract

A method for preparing methyl silicone resin for high-temperature mica boards includes: (1) Solution A is a mixture of methyltrimethoxysilane, dimethyldimethoxysilane, and epoxysilane coupling agent, which account for 87%-95%, 3%-7%, and 2%-6% of the total amount of A, respectively; (2) Adding 0.5-1.0 times the amount of benzene solvent, 0.2-0.3 times the amount of isopropanol, and adding 0.5%-1% of the total amount of A acidic catalyst to obtain solution B; (3) Heating B to 70℃-80℃, and uniformly adding deionized water, and adding... The time is controlled at 2-3 hours. After the addition is completed, continue stirring for half an hour to obtain solution C. The amount of deionized water is 40%-50% of the total amount of A. (4) Transfer C to a separatory funnel and let it stand to separate into layers. The lower layer of methanol solution is purified by distillation, and the upper layer of silanol solution is washed with water until neutral to obtain solution D. (5) Heat D and reflux for condensation reaction. Maintain the temperature at 130℃-140℃ for half an hour, then cool to room temperature and add benzene solvent to form a 50%-60% concentration of methyl silicone resin for high-temperature mica boards. The benzene solvent content is 40%-50%. It is environmentally friendly, has a simple process, excellent bending resistance, and good moisture resistance.

Description

Technical Field

[0001] This invention relates to the field of organic chemical synthesis, and specifically to a method for preparing methyl silicone resin for high-temperature mica boards. Background Technology

[0002] High-temperature mica board is made by baking and pressing mica paper as a base material and methyl silicone resin as a binder at high temperatures. Mica boards made with methyl silicone resin as an adhesive possess excellent properties such as resistance to high and low temperatures, electrical insulation, low weight loss at high temperatures, low smoke emission, moisture resistance, and water resistance. They are widely used in industries such as new energy vehicles, home appliances, metallurgy, and chemicals.

[0003] In patent CN113637450A, the inventors proposed adding a mixture of methyltrichlorosilane and toluene dropwise to a mixture of n-butanol, toluene, and deionized water. After the reaction was complete, the mixture was allowed to stand and separate into layers. The lower layer of acidic water was removed, and the upper silanol solution was washed with water until neutral. Then, the mixture was heated and stirred, concentrated, and polymerized to obtain a methyl silicone resin product. However, this preparation method generates a large amount of hydrogen chloride during the hydrolysis of methyltrichlorosilane, and the upper silanol solution requires multiple washes with a large amount of water to reach neutrality. The production process generates a large amount of acidic wastewater containing organic solvents and hydrogen chloride gas. The hydrogen chloride gas causes severe corrosion to equipment and environmental pollution, and the waste gas and wastewater treatment costs are extremely high. The mica boards made using this methyl silicone resin have generally poor bending strength and moisture resistance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing methyl silicone resin for high-temperature mica boards that is environmentally friendly, simple in process, has excellent bending strength, and better moisture resistance.

[0005] The preparation method of methyl silicone resin for high-temperature mica plates of the present invention is carried out according to the following steps: (1) Mix methyltrimethoxysilane, dimethyldimethoxysilane, and epoxy silane coupling agent to form solution A, wherein methyltrimethoxysilane accounts for 87%-95% of the total amount of solution A, dimethyldimethoxysilane accounts for 3%-7% of the total amount of solution A, and epoxy silane coupling agent accounts for 2%-6% of the total amount of solution A; (2) Add 0.5-1.0 times the amount of benzene solvent and 0.2-0.3 times the amount of isopropanol to solution A, and add an acidic catalyst at 0.5%-1% of the total amount of solution A to obtain solution B; (3) Heat solution B to 70℃-80℃, add deionized water dropwise at a uniform rate, and control the addition time to 2-3 hours. After the addition is complete, continue stirring for half an hour to obtain solution C. The amount of deionized water used is 40%-50% of the total amount of A. (4) Transfer solution C to a separatory funnel and allow it to stand to separate into layers. Purify the lower methanol layer by distillation and wash the upper silanol layer with an appropriate amount of water until neutral to obtain solution D; (5) Heat solution D and reflux it to condense the reaction. Maintain the temperature at 130℃-140℃ for half an hour. When the temperature drops to room temperature, add benzene solvent to prepare a methyl silicone resin for high-temperature mica boards with a concentration of 50%-60%, wherein the benzene solvent content is 40%-50%.

[0006] As a preferred method, the benzene solvent is one or a mixture of toluene and xylene.

[0007] As a preferred method, the amount of dimethyldimethoxysilane used is preferably 3% to 7% of the total amount of solution A.

[0008] As a preferred method, the epoxy silane coupling agent is preferably one or a mixture of β-(3,4-epoxycyclohexane)ethyltrimethoxysilane (KH-566), 3-glycidyl etheroxypropyltrimethoxysilane (KH-560), and 3-glycidyl etheroxypropyltriethoxysilane (KH-561).

[0009] As a preferred approach, the acidic catalyst is an organic acid or an inorganic acid.

[0010] As a preferred method, the acidic catalyst is preferably one of toluenesulfonic acid, hydrochloric acid, and formic acid.

[0011] As a preferred method, methyl silicone resin for high-temperature mica boards is a polysiloxane with silicon-oxygen bonds as the main chain. After curing and cross-linking, it becomes a slightly elastic and tough cross-linked resin. The molecular weight is 7000-8000, the hydroxyl content is 2%-3%, and the low-boiling point content is less than 0.3%.

[0012] The methyl silicone resin used in the preparation of high-temperature mica boards of this invention uses raw materials such as methyltrimethoxysilane, dimethyldimethoxysilane, epoxy silane coupling agent, benzene solvent, and isopropanol.

[0013] This invention, after extensive experimental screening, employs a reverse hydrolysis method. A siloxane monomer, an epoxy silane coupling agent, a benzene solvent, and isopropanol are mixed in a specific ratio and added to a four-necked flask along with an acidic catalyst. Deionized water is poured into a constant-pressure dropping funnel and added dropwise to the flask at a uniform rate, while the reaction temperature is maintained in a water bath. After the addition is complete, stirring continues for half an hour. The material is then transferred to a separating funnel and allowed to separate into layers. The lower methanol layer is purified by distillation, and the upper silanol layer is washed with water until neutral. The neutral silanol solution is heated and stirred under reflux for condensation. After cooling, a benzene solvent is added to prepare a 50%-60% concentration methyl silicone resin for high-temperature mica boards. The water from the distillation of the lower methanol layer and the washing water are neutralized and reused for the hydrolysis of the siloxane.

[0014] Compared with existing technologies, the advantages of this invention are: the raw materials used in this invention are all conventional reagents, which are inexpensive, the synthesis process is simple and easy to control, and it is suitable for large-scale production. There is no gel formation during the production process, and water is recycled without external discharge. The methyl silicone resin prepared by this invention, due to the introduction of epoxy groups, can significantly increase the adhesiveness of the silicone resin and improve its hydrophobic properties. Attached Figure Description

[0015] Figure 1 Comparison data table of Examples 1-3 of the present invention and methyl silicone resin for ordinary mica boards. Detailed Implementation

[0016] In the following description, embodiments of a method for preparing methyl silicone resin for high-temperature mica boards according to the present invention will be described with reference to the accompanying drawings and examples.

[0017] The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the invention, and are illustrative and exemplary, and should not be construed as limiting the implementation and scope of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0018] The steps of the preparation method of methyl silicone resin for high-temperature mica board according to the present invention are as follows: (1) Mix methyltrimethoxysilane, dimethyldimethoxysilane, and epoxy silane coupling agent to form solution A, wherein methyltrimethoxysilane accounts for 87%-95% of the total amount of solution A, dimethyldimethoxysilane accounts for 3%-7% of the total amount of solution A, and epoxy silane coupling agent accounts for 2%-6% of the total amount of solution A; (2) Add 0.5-1.0 times the amount of benzene solvent and 0.2-0.3 times the amount of isopropanol to solution A, and add an acidic catalyst at 0.5%-1% of the total amount of solution A to obtain solution B; (3) Heat solution B to 70℃-80℃, add deionized water dropwise at a uniform rate, and control the addition time to 2-3 hours. After the addition is complete, continue stirring for half an hour to obtain solution C. The amount of deionized water used is 40%-50% of the total amount of A. (4) Transfer solution C to a separatory funnel and allow it to stand to separate into layers. Purify the lower methanol layer by distillation and wash the upper silanol layer with an appropriate amount of water until neutral to obtain solution D; (5) Heat solution D and reflux it to condense the reaction. Maintain the temperature at 130℃-140℃ for half an hour. When the temperature drops to room temperature, add benzene solvent to prepare methyl silicone resin for high-temperature mica boards with a concentration of 50%-60%.

[0019] In this invention, the benzene solvent can be one or a mixture of toluene and xylene.

[0020] In this invention, the amount of dimethyldimethoxysilane used is preferably 3%-7% of the total amount of solution A.

[0021] In this invention, 2%-6% of the total amount of solution A is used as an epoxy silane coupling agent. With the help of epoxy silane, epoxy groups are introduced, which can significantly increase the adhesion of silicone resin and improve the hydrophobic properties of silicone resin.

[0022] In this invention, the epoxy silane coupling agent is preferably one or a mixture of β-(3,4-epoxycyclohexane)ethyltrimethoxysilane (KH-566), 3-glycidyl etheroxypropyltrimethoxysilane (KH-560), and 3-glycidyl etheroxypropyltriethoxysilane (KH-561).

[0023] In this invention, the acidic catalyst can be an organic acid or an inorganic acid.

[0024] Furthermore, the acidic catalyst is preferably one of toluenesulfonic acid, hydrochloric acid, or formic acid.

[0025] In this invention, the solid content of methyl silicone resin is 50%-60%, and the content of toluene or xylene is 40%-50%.

[0026] In this invention, the methyl silicone resin for high-temperature mica boards is a polysiloxane with silicon-oxygen bonds as the main chain, which, after curing and cross-linking, becomes a slightly elastic and tough cross-linked resin. It has a molecular weight of 7000-8000, a hydroxyl content of 2%-3%, and a low-boiling-point content of less than 0.3%.

[0027] Examples 1, 2 and 3 are given below for preparing methyl silicone resin for high-temperature mica boards according to the above method.

[0028] Example 1 In a 1000ml four-necked flask, 261g of methyltrimethoxysilane, 27g of dimethyldimethoxysilane, and 18g of β-(3,4-epoxycyclohexane)ethyltrimethoxysilane were added to obtain solution A. Then, 150g of toluene, 60g of isopropanol, and 1.5g of hydrochloric acid were added to solution A to obtain solution B. Solution B was heated to 70℃, and 120g of deionized water was added dropwise over 2 hours. After the addition was complete, the reaction continued for half an hour to obtain solution C, with the reaction temperature maintained in a water bath. Solution C was transferred to a separatory funnel for separation. The lower alcoholic solution was discarded, and the upper intermediate silicon solution was washed with a small amount of water until neutral to obtain solution D. Solution D was heated to perform a reflux condensation reaction, maintaining the temperature at 130-140℃ for half an hour. After the temperature dropped to room temperature, toluene was added to prepare a 50% solids methyl silicone resin.

[0029] Example 2 In a 1000ml four-necked flask, 285g of methyltrimethoxysilane, 9g of dimethyldimethoxysilane, and 6g of 3-glycidyl etheroxypropyltrimethoxysilane were added to obtain solution A. Then, 300g of xylene, 90g of isopropanol, and 3g of formic acid were added to solution A to obtain solution B. Solution B was heated to 80℃, and 150g of deionized water was added dropwise over 3 hours. After the addition was complete, the reaction continued for half an hour to obtain solution C, with the reaction temperature maintained in a water bath. Solution C was transferred to a separatory funnel for separation. The lower alcoholic solution was discarded, and the upper intermediate silicon solution was washed with a small amount of water until neutral to obtain solution D. Solution D was heated to perform a reflux condensation reaction, maintaining the temperature at 130-140℃ for half an hour. After the temperature dropped to room temperature, toluene was added to prepare a 50% solids methyl silicone resin.

[0030] Example 3 In a 1000ml four-necked flask, 270g of methyltrimethoxysilane, 20g of dimethyldimethoxysilane, and 12g of 3-glycidyl etheroxypropyltriethoxysilane were added to obtain solution A. Then, 250g of toluene, 80g of isopropanol, and 2g of hydrochloric acid were added to solution A to obtain solution B. Solution B was heated to 75°C, and 130g of deionized water was added dropwise over 2.5 hours. After the addition was complete, the reaction continued for another half hour to obtain solution C, with the reaction temperature maintained in a water bath. Solution C was transferred to a separatory funnel for separation. The lower alcoholic solution was discarded, and the upper intermediate silicon solution was washed with a small amount of water until neutral to obtain solution D. Solution D was heated to perform a reflux condensation reaction, maintaining the temperature at 130-140°C for half an hour. After the temperature dropped to room temperature, toluene was added to prepare a 60% solids methyl silicone resin.

[0031] The comparison results between the methyl silicone resin prepared in this embodiment and the methyl silicone resin used in ordinary mica boards are as follows: Figure 1 As shown, Figure 1 This is a comparison data table of methyl silicone resin used in Examples 1-3 and ordinary mica boards.

[0032] like Figure 1 As shown in the comparison table, the mica sheets made using Examples 1-3 can significantly increase the bending strength of the mica sheets, while also improving their hydrophobic properties.

[0033] The specific embodiments of the preparation method of methyl silicone resin for high-temperature mica boards proposed in this invention have been described in detail above, with the aim of illustrating the technical concept and core spirit of this invention. It should be understood that those skilled in the art can make adaptive modifications, equivalent substitutions, and reasonable combinations of the technical features in the above embodiments without departing from the essential spirit and technical solution of this invention. Therefore, the scope of protection of this invention should not be limited to the specific embodiments described above. Furthermore, the technical features disclosed in this specification are not limited to the disclosed combinations. Those skilled in the art can make other reasonable combinations and arrangements of the technical features according to the inventive purpose of this invention. As long as such combinations can achieve the technical purpose of this invention, they should fall within the scope of protection of this invention.

Claims

1. A method for preparing methyl silicone resin for high-temperature mica boards, comprising the following steps: (1) Mix methyltrimethoxysilane, dimethyldimethoxysilane, and epoxy silane coupling agent to form solution A, wherein methyltrimethoxysilane accounts for 87%-95% of the total amount of solution A, dimethyldimethoxysilane accounts for 3%-7% of the total amount of solution A, and epoxy silane coupling agent accounts for 2%-6% of the total amount of solution A; (2) Add 0.5-1.0 times the amount of benzene solvent and 0.2-0.3 times the amount of isopropanol to solution A, and add an acidic catalyst at 0.5%-1% of the total amount of solution A to obtain solution B; (3) Heat solution B to 70℃-80℃, add deionized water dropwise at a uniform rate, and control the addition time to 2-3 hours. After the addition is complete, continue stirring for half an hour to obtain solution C. The amount of deionized water used is 40%-50% of the total amount of A. (4) Transfer solution C to a separatory funnel and allow it to stand to separate into layers. Purify the lower layer of methanol solution by distillation, and wash the upper layer of silanol solution with an appropriate amount of water until neutral to obtain solution D; (5) Heat solution D and reflux it to condense the reaction. Maintain the temperature at 130℃-140℃ for half an hour. When the temperature drops to room temperature, add benzene solvent to prepare a methyl silicone resin for high-temperature mica boards with a concentration of 50%-60%, wherein the benzene solvent content is 40%-50%.

2. The method for preparing methyl silicone resin for high-temperature mica boards according to claim 1, characterized in that: The benzene solvent is one or a mixture of toluene and xylene.

3. The method for preparing methyl silicone resin for high-temperature mica boards according to claim 1, characterized in that: The preferred amount of dimethyldimethoxysilane is 3%–7% of the total amount of solution A.

4. The method for preparing methyl silicone resin for high-temperature mica boards according to claim 1, characterized in that: The epoxy silane coupling agent is preferably one or a mixture of β-(3,4-epoxycyclohexane)ethyltrimethoxysilane (KH-566), 3-glycidyl etheroxypropyltrimethoxysilane (KH-560), and 3-glycidyl etheroxypropyltriethoxysilane (KH-561).

5. The method for preparing methyl silicone resin for high-temperature mica boards according to claim 1, characterized in that: The acidic catalyst is an organic acid or an inorganic acid.

6. The method for preparing methyl silicone resin for high-temperature mica boards according to claim 1, characterized in that: The acidic catalyst is preferably one of toluenesulfonic acid, hydrochloric acid, and formic acid.

7. The method for preparing methyl silicone resin for high-temperature mica boards according to claim 1, characterized in that: The methyl silicone resin used in high-temperature mica boards is a polysiloxane with silicon-oxygen bonds as the main chain. After curing and cross-linking, it becomes a slightly elastic and tough cross-linked resin. It has a molecular weight of 7000-8000, a hydroxyl content of 2%-3%, and a low-boiling-point content of less than 0.3%.

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