Polymethoxy-terminated structured auxiliary agent and preparation method thereof, and high-transparency silicone rubber

Abstract

The invention relates to the technical field of polymers, and discloses a polymethoxy-terminated structured assistant, a preparation method and high-transparency silicone rubber, the structured assistant comprises the following raw materials: methyltrimethoxysilane, a solvent, a silane coupling agent, a reactant and a terminator, the structured auxiliary agent is prepared from methyltrimethoxysilane as a main raw material through hydrolytic polycondensation reaction, the viscosity of the structured auxiliary agent is 2-20 cst, the structured auxiliary agent is not easy to volatilize, the flammable and explosive risk is low, the safety is high, the structured auxiliary agent is terminated by polymethoxy groups, the content is large, the activity is high, the surface of the white carbon black can be effectively modified, the dispersity of the white carbon black is improved, and the service life of the white carbon black is prolonged. The product obtained after the reaction of the structured auxiliary agent and white carbon black is methanol which is easy to remove, and the transparency of the silicone rubber can be remarkably improved.

Description

Technical Field

[0001] The invention relates to the field of polymer technology, and in particular to a polymethoxy-terminated structural auxiliary agent and a preparation method thereof, and highly transparent silicone rubber. Background Art

[0002] Structuring additive is an important functional additive for organic silicon rubber compound, which can modify the surface of silica, improve the compatibility and dispersibility of silica in the compound, lubricate the molecular structure of silicone rubber, and improve the processing performance of the compound. At present, the commonly used structuring additive is hydroxy silicone oil, such as the technical scheme of publication number CN101570601B. Hydroxyl silicone oil contains 5-10% hydroxyl group, which has a good effect on the surface modification of silica. However, the polarity of hydroxy silicone oil is greater than that of silicone rubber, and it generates water after reacting with the hydroxyl group on the surface of silica. Therefore, the compound prepared with it has a large viscosity before vulcanization, and the transparency of the product after vulcanization is poor.

[0003] Therefore, in order to alleviate the above problems, methoxy silicone oil and hydroxy silicone oil are used together as structuring additives in the prior art. The viscosity of methoxy silicone oil is generally 3-5 cst, and it is terminated with methoxy groups. It has good compatibility with silicone rubber, and it reacts with the hydroxyl groups on the surface of silica to generate methanol, which is easy to remove. Therefore, the appearance of the mixed rubber prepared by it is more delicate before vulcanization, and the viscosity is lower. The transparency of the product after vulcanization is also higher than that of the single use of hydroxy silicone oil. However, due to the poor surface modification effect of methoxy silicone oil on silica, it is difficult to effectively improve the dispersibility of silica, so the subsequent Continuously increasing its dosage, or even using it alone as a structuring agent, has no obvious effect on further improving the transparency of the mixed rubber. In addition, vinyl trimethoxy silane, vinyl triethoxy silane, etc. are also often used as structuring agents, such as the high thermal conductivity silicone rubber thermal interface material and preparation method using hydroxy silicone oil and methyl ethyl silicone oil disclosed in publication number CN106317886A, which is also helpful in promoting the dispersion of white carbon black and improving the transparency of the mixed rubber, but they all have defects such as low viscosity, high volatility, low flash point, and flammability and explosion. Summary of the invention

[0004] In order to overcome the problems of volatility, flammability, explosion and low safety of the structuring additives in the prior art, the present invention provides a polymethoxy-terminated structuring additive and a preparation method, and a highly transparent silicone rubber. The structuring additive uses methyltrimethoxysilane as a main raw material, and is prepared by hydrolysis and polycondensation reaction to have a viscosity of 2 to 20 cst, is not volatile, has a low risk of combustion and explosion, and is highly safe. The structuring additive is polymethoxy-terminated, has a large content, high activity, can effectively modify the surface of silica, and improve the dispersibility of silica. The product of the reaction between the structuring additive and silica is methanol, which is easy to remove and can significantly improve the transparency of the silicone rubber.

[0005] The specific technical scheme of the present invention is: A polymethoxy-terminated structuring auxiliary agent, the raw materials of which include methyltrimethoxysilane, a solvent, a silane coupling agent, a catalyst, water and a terminator.

[0006] Preferably, the molar ratio of methyltrimethoxysilane to solvent is 1:0.5-5.

[0007] Preferably, the molar ratio of methyltrimethoxysilane to water is 1:0.5-2.

[0008] Preferably, the molar ratio of methyltrimethoxysilane to catalyst is 1:10 -4 ~10 -2 .

[0009] Preferably, the molar ratio of the methyltrimethoxysilane to the silane coupling agent is 1:0 to 0.1.

[0010] Preferably, the molar ratio of the terminator to the catalyst is 1 to 4:1.

[0011] Preferably, the catalyst is one of hydrochloric acid, sulfuric acid, nitric acid and acetic acid.

[0012] Preferably, the terminator is one of calcium carbonate, calcium oxide and magnesium oxide.

[0013] Preferably, the solvent is one or more of methanol, ethanol and isopropanol.

[0014] Preferably, the viscosity of the polymethoxy-terminated structuring aid is 2 to 20 cst.

[0015] Preferably, the silane coupling agent is one of vinyltrimethoxysilane, vinyltriethoxysilane, dimethyldimethoxysilane and dimethyldiethoxysilane.

[0016] The invention provides a polymethoxy-terminated structuring auxiliary agent, which is prepared by hydrolyzing and polycondensing methyltrimethylsilane and a silane coupling agent, has a viscosity of 2 to 20 cst, is not easily volatile, has a low risk of combustion and explosion, and is highly safe. The structuring auxiliary agent is polymethoxy-terminated, has a large content, and is highly active, and can effectively modify the surface of white carbon black and improve the dispersibility of white carbon black. The product of the reaction between the structuring auxiliary agent and white carbon black is methanol, which is easy to remove and can significantly improve the transparency of silicone rubber.

[0017] A method for preparing the above-mentioned polymethoxy-terminated structuring auxiliary agent comprises the following steps: uniformly mixing methyltrimethoxysilane, a silane coupling agent and methanol, adding a reactant to carry out a hydrolysis and polycondensation reaction, adding a terminator to terminate the reaction to obtain a mixture, and distilling and filtering the mixture to obtain the polymethoxy-terminated structuring auxiliary agent.

[0018] Preferably, the temperature of the hydrolysis and polycondensation reaction is 30-60°C.

[0019] Preferably, the hydrolysis and polycondensation reaction time is 3 to 5 hours.

[0020] Preferably, the distillation temperature is 60-100°C.

[0021] A highly transparent silicone rubber, the raw materials of which include: methyl vinyl rubber, white carbon black, a structuring aid and a release agent, wherein the structuring aid includes hydroxy silicone oil and the above-mentioned polymethoxy-terminated structuring aid.

[0022] Compared with the prior art, this application has the following technical effects: The invention provides a polymethoxy-terminated structuring auxiliary agent and a preparation method thereof, and highly transparent silicone rubber. The structuring auxiliary agent adopts methyltrimethoxysilane as a main raw material and is prepared by hydrolysis and polycondensation reaction. The structuring auxiliary agent has a viscosity of 2 to 20 cst, is not easy to volatilize, has a low risk of combustion and explosion, and is highly safe. The structuring auxiliary agent is polymethoxy-terminated, has a large content, and is highly active. The surface of white carbon black can be effectively modified to improve the dispersibility of white carbon black. The product of the reaction between the structuring auxiliary agent and white carbon black is methanol, which is easy to remove and can significantly improve the transparency of the silicone rubber. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the embodiments.

[0024] Embodiment 1: A polymethoxy-terminated structural auxiliary agent, the raw materials include: 1 mol of methyltrimethoxysilane, 5 mol of solvent Hydrochloric acid 10 -4 mol, water 0.5 mol, terminator 10 -4 mol, the solvent is methanol, no silane coupling agent is added, the terminator is calcium carbonate, and the viscosity of the polymethoxy-terminated structuring additive is 2cst.

[0025] A preparation method of the above-mentioned polymethoxy-terminated structuring auxiliary agent comprises the following steps: uniformly mixing methyltrimethoxysilane and methanol at room temperature, slowly adding a mixed solution of hydrochloric acid and water, heating to 30°C for hydrolysis and polycondensation reaction for 5 hours, adding calcium carbonate to terminate the reaction to prepare a mixture, further heating to 60°C, distilling to remove the solvent in the mixture, and filtering to obtain the polymethoxy-terminated structuring auxiliary agent.

[0026] A highly transparent silicone rubber, the raw materials comprising by weight: 100 parts of methyl vinyl rubber, viscosity 650,000, vinyl content 0.08%, 30 parts of white carbon black, white carbon black is fumed white carbon black, specific surface area 200m 2 / g, 5 parts of structuring aids, including 1 part of hydroxy silicone oil and 4 parts of polymethoxy-terminated structuring aids, the content of hydroxyl groups in the hydroxy silicone oil is 8%, 0.1 part of release agent, the release agent is zinc stearate.

[0027] Embodiment 2: A polymethoxy-terminated structural auxiliary agent, the raw materials include: 1 mol of methyltrimethoxysilane, 0.5 mol of solvent Sulfuric acid 3×10 -4 mol, water 2mol, terminator 12×10 -4 mol, the solvent is methanol, no silane coupling agent is added, the terminator is magnesium oxide, and the viscosity of the polymethoxy-terminated structuring additive is 20 cst.

[0028] A method for preparing the above-mentioned polymethoxy-terminated structuring auxiliary agent comprises the following steps: Methyltrimethoxysilane and methanol were mixed evenly at room temperature, and then a mixed solution of sulfuric acid and water was slowly added, the temperature was raised to 60°C for hydrolysis and condensation reaction for 4 hours, and then magnesium oxide was added to terminate the reaction to prepare a mixture, and then the temperature was continued to be raised to 80°C, the solvent in the mixture was distilled off, and then filtered to obtain a polymethoxy-terminated structuring additive.

[0029] A highly transparent silicone rubber, the raw materials comprising by weight: 100 parts of methyl vinyl rubber, viscosity 650,000, 50 parts of vinyl content 0.08% and 0.05%, 50 parts of white carbon black, white carbon black is fumed white carbon black, with a specific surface area of ​​200m 2 / g, 10 parts of structuring aids, including 2 parts of hydroxy silicone oil and 8 parts of polymethoxy-terminated structuring aids, the content of hydroxyl groups in the hydroxy silicone oil is 8%, 0.5 parts of release agent, the release agent is zinc stearate.

[0030] Embodiment 3: A polymethoxy-terminated structural auxiliary agent, the raw materials include: 1 mol of methyltrimethoxysilane, 0.1 parts of a silane coupling agent, 2 mol of a solvent, 10 parts of nitric acid -3 mol, water 1.2 mol, terminator 3×10 -3 mol, the solvent is methanol, the silane coupling agent is vinyl trimethoxy silane, the terminator is calcium oxide, and the viscosity of the polymethoxy-terminated structuring additive is 18 cst.

[0031] A preparation method of the above-mentioned polymethoxy-terminated structuring auxiliary agent comprises the following steps: uniformly mixing methyltrimethoxysilane, vinyltrimethoxysilane and methanol at room temperature, slowly adding a mixed solution of nitric acid and water, heating to 40°C for hydrolysis and polycondensation reaction for 4 hours, adding calcium oxide to terminate the reaction to prepare a mixture, further heating to 80°C, distilling to remove the solvent in the mixture, and filtering to obtain the polymethoxy-terminated structuring auxiliary agent.

[0032] A highly transparent silicone rubber, the raw materials comprising by weight: 100 parts of methyl vinyl rubber, viscosity 650,000, 50 parts of vinyl content 0.08% and 0.05%, 40 parts of white carbon black, white carbon black is fumed white carbon black, with a specific surface area of ​​200m 2 / g, 8 parts of structuring aids, including 2 parts of hydroxy silicone oil and 6 parts of polymethoxy-terminated structuring aids, the content of hydroxyl groups in the hydroxy silicone oil is 8%, 0.2 parts of release agent, the release agent is zinc stearate.

[0033] Embodiment 4: A polymethoxy-terminated structural auxiliary agent, the raw materials include: 1 mol of methyltrimethoxysilane, 0.05 parts of silane coupling agent, 3 mol of solvent, 10 parts of acetic acid -2 mol, water 1.8 mol, terminator 4×10 -2 mol, the solvent is isopropanol, the silane coupling agent is 0.03 parts of isobutyltrimethoxysilane and 0.02 parts of isobutyltriethoxysilane, the terminator is calcium carbonate, and the viscosity of the polymethoxy-terminated structuring additive is 14 cst.

[0034] A preparation method of the above-mentioned polymethoxy-terminated structuring auxiliary agent comprises the following steps: uniformly mixing methyltrimethoxysilane, isobutyltrimethoxysilane and isopropanol at room temperature, slowly adding a mixed solution of acetic acid and water, heating to 60°C for hydrolysis and polycondensation reaction for 4 hours, adding calcium carbonate to terminate the reaction to prepare a mixture, further heating to 100°C, distilling to remove the solvent in the mixture, and filtering to obtain the polymethoxy-terminated structuring auxiliary agent.

[0035] A highly transparent silicone rubber, the raw materials comprising by weight: 100 parts of methyl vinyl rubber, viscosity 650,000, 40 parts of vinyl content 0.08%, 60 parts of vinyl content 0.05%, 35 parts of white carbon black, white carbon black is fumed white carbon black, specific surface area 300m 2 / g, 9 parts of structuring aids, including 3 parts of hydroxy silicone oil and 6 parts of polymethoxy-terminated structuring aids, the content of hydroxyl groups in the hydroxy silicone oil is 8%, 0.1 part of release agent, the release agent is zinc stearate.

[0036] Embodiment 5: A polymethoxy-terminated structural auxiliary agent, the raw materials include: 1 mol of methyltrimethoxysilane, 0.02 parts of silane coupling agent, 2 mol of solvent, 10 parts of hydrochloric acid -4 mol, water 1 mol, terminator 4×10 -4 mol, the solvent is ethanol, the silane coupling agent is 0.01 part of dimethyldimethoxysilane and 0.01 part of vinyltriethoxysilane, the terminator is calcium carbonate, and the viscosity of the polymethoxy-terminated structuring additive is 8.5 cst.

[0037] A preparation method of the above-mentioned polymethoxy-terminated structuring auxiliary agent comprises the following steps: uniformly mixing methyltrimethoxysilane, dibutyldimethoxysilane and ethanol at room temperature, slowly adding a mixed solution of hydrochloric acid and water, heating to 60°C for hydrolysis and polycondensation reaction for 3 hours, adding calcium carbonate to terminate the reaction to prepare a mixture, further heating to 80°C, distilling to remove the solvent in the mixture, and filtering to obtain the polymethoxy-terminated structuring auxiliary agent.

[0038] A highly transparent silicone rubber, the raw materials comprising by weight: 100 parts of methyl vinyl rubber, viscosity 650,000, 90 parts of vinyl content 0.08%, 10 parts of vinyl content 0.12%, 30 parts of white carbon black, white carbon black is fumed white carbon black, specific surface area 200m 2 / g, 8 parts of structuring aids, including 2 parts of hydroxy silicone oil and 6 parts of polymethoxy-terminated structuring aids, the content of hydroxyl groups in the hydroxy silicone oil is 8%, 0.1 part of release agent, the release agent is stearic acid.

[0039] Embodiment 6: A polymethoxy-terminated structural auxiliary agent, the raw materials include: 1 mol of methyltrimethoxysilane, 2 mol of solvent, 2×10 -4 mol, water 1.2 mol, terminator 4×10 -4 mol, the solvent is methanol, no silane coupling agent is added, the terminator is calcium carbonate, and the viscosity of the polymethoxy-terminated structuring additive is 12.5 cst.

[0040] A preparation method of the above-mentioned polymethoxy-terminated structuring auxiliary agent comprises the following steps: uniformly mixing methyltrimethoxysilane and methanol at room temperature, slowly adding a mixed solution of hydrochloric acid and water, heating to 60°C for hydrolysis and polycondensation reaction for 3 hours, adding calcium carbonate to terminate the reaction to prepare a mixture, further heating to 80°C, distilling to remove the solvent in the mixture, and filtering to obtain the polymethoxy-terminated structuring auxiliary agent.

[0041] A highly transparent silicone rubber, the raw materials comprising by weight: 100 parts of methyl vinyl rubber, viscosity 650,000, vinyl content 0.08% 95 parts, vinyl content 0.12% 5 parts, 60 parts of white carbon black, white carbon black is fumed white carbon black, specific surface area 200m 2 / g, 9 parts of structuring aids, including 0 parts of hydroxy silicone oil and 9 parts of polymethoxy-terminated structuring aids, and 0.1 parts of a release agent, which is zinc stearate.

[0042] Embodiment 7: A polymethoxy-terminated structural auxiliary agent, the raw materials include: 1 mol of methyltrimethoxysilane, 1 mol of solvent, 1.5×10 -4 mol, water 1.4 mol, terminator 6×10 -4 mol, the solvent is methanol, no silane coupling agent is added, the terminator is magnesium oxide, and the viscosity of the polymethoxy-terminated structuring additive is 17.9 cst.

[0043] A preparation method of the above-mentioned polymethoxy-terminated structuring auxiliary agent comprises the following steps: uniformly mixing methyltrimethoxysilane and methanol at room temperature, slowly adding a mixed solution of hydrochloric acid and water, heating to 55°C for hydrolysis and polycondensation reaction for 3 hours, adding calcium carbonate to terminate the reaction to prepare a mixture, further heating to 70°C, distilling to remove the solvent in the mixture, and filtering to obtain the polymethoxy-terminated structuring auxiliary agent.

[0044] A highly transparent silicone rubber, the raw materials include, by mass: 100 parts of methyl vinyl rubber, with a viscosity of 650,000 and a vinyl content of 0.08%, and 45 parts of white carbon black, which is fumed white carbon black with a specific surface area of ​​200m 2 / g, 10 parts of structuring aids, which include 0 parts of hydroxy silicone oil and 10 parts of polymethoxy-terminated structuring aids, and 0.2 parts of a release agent, which is zinc stearate.

[0045] Comparative Example 1: Compared with Example 6, in Comparative Example 1, all the polymethoxy-terminated structuring additives were replaced with methoxy silicone oils; A highly transparent silicone rubber, the raw materials comprising by weight: 100 parts of methyl vinyl rubber, viscosity 650,000, vinyl content 0.08% 95 parts, vinyl content 0.12% 5 parts, 60 parts of white carbon black, white carbon black is fumed white carbon black, specific surface area 200m 2 / g, 9 parts of structuring aid, the structuring aid is methoxy silicone oil, 0.1 part of release agent, the release agent is zinc stearate.

[0046] Comparative Example 2: Compared with Example 6, in Comparative Example 1, the polymethoxy-terminated structuring auxiliary agent is replaced with hydroxy silicone oil; A highly transparent silicone rubber, the raw materials comprising by weight: 100 parts of methyl vinyl rubber, viscosity 650,000, vinyl content 0.08% 95 parts, vinyl content 0.12% 5 parts, 60 parts of white carbon black, white carbon black is fumed white carbon black, specific surface area 200m 2 / g, 9 parts of structuring aid, the structuring aid is hydroxy silicone oil, hydroxyl value 8%, 0.1 part of release agent, the release agent is zinc stearate.

[0047] Comparative Example 3: Compared with Example 6, in Comparative Example 3, 1.2 mol of water was replaced with 2.2 mol, and the viscosity of the polymethoxy-terminated structuring additive was 31.8 cst; A polymethoxy-terminated structural auxiliary agent, the raw materials include: 1 mol of methyltrimethoxysilane, 2 mol of solvent, 2×10 -4 mol, water 2.2 mol, terminator 4×10 -4 mol, the solvent is methanol, no silane coupling agent is added, the terminator is calcium carbonate, and the viscosity of the polymethoxy-terminated structuring additive is 31.8 cst.

[0048] A preparation method of the above-mentioned polymethoxy-terminated structuring auxiliary agent comprises the following steps: uniformly mixing methyltrimethoxysilane and methanol at room temperature, slowly adding a mixed solution of hydrochloric acid and water, heating to 60°C for hydrolysis and polycondensation reaction for 3 hours, adding calcium carbonate to terminate the reaction to prepare a mixture, further heating to 80°C, distilling to remove the solvent in the mixture, and filtering to obtain the polymethoxy-terminated structuring auxiliary agent.

[0049] Comparative Example 4: Compared with Example 6, in Comparative Example 4, 1.2 mol of water was replaced with 0.2 mol, and the viscosity of the polymethoxy-terminated structuring additive was 1.5 cst; A polymethoxy-terminated structural auxiliary agent, the raw materials include: 1 mol of methyltrimethoxysilane, 2 mol of solvent, 2×10 -4mol, water 0.2 mol, terminator 4×10 -4 mol, the solvent is methanol, no silane coupling agent is added, the terminator is calcium carbonate, and the viscosity of the polymethoxy-terminated structuring additive is 1.5 cst.

[0050] A preparation method of the above-mentioned polymethoxy-terminated structuring auxiliary agent comprises the following steps: uniformly mixing methyltrimethoxysilane and methanol at room temperature, slowly adding a mixed solution of hydrochloric acid and water, heating to 60°C for hydrolysis and polycondensation reaction for 3 hours, adding calcium carbonate to terminate the reaction to prepare a mixture, further heating to 80°C, distilling to remove the solvent in the mixture, and filtering to obtain the polymethoxy-terminated structuring auxiliary agent.

[0051] Comparative Example 5: Compared with Example 6, in Comparative Example 5, 2 mol of methanol was replaced with 0.2 mol, and the other contents remained unchanged. The viscosity of the polymethoxy-terminated structuring additive was 21.5 cst; A polymethoxy-terminated structural auxiliary agent, the raw materials include: 1 mol of methyltrimethoxysilane, 0.2 mol of solvent, 2×10 -4 mol, water 0.2 mol, terminator 4×10 -4 mol, the solvent is methanol, no silane coupling agent is added, the terminator is calcium carbonate, and the viscosity of the polymethoxy-terminated structuring additive is 21.5 cst.

[0052] A preparation method of the above-mentioned polymethoxy-terminated structuring auxiliary agent comprises the following steps: uniformly mixing methyltrimethoxysilane and methanol at room temperature, slowly adding a mixed solution of hydrochloric acid and water, heating to 60°C for hydrolysis and polycondensation reaction for 3 hours, adding calcium carbonate to terminate the reaction to prepare a mixture, further heating to 80°C, distilling to remove the solvent in the mixture, and filtering to obtain the polymethoxy-terminated structuring auxiliary agent.

[0053] Comparative Example 6: Compared with Example 6, in Comparative Example 6, 2 mol of methanol was replaced with 6 mol, and the other contents remained unchanged, and the viscosity of the polymethoxy-terminated structuring additive was 1.9 cst; A polymethoxy-terminated structural auxiliary agent, the raw materials include: 1 mol of methyltrimethoxysilane, 6 mol of solvent, 2×10 -4 mol, water 0.2 mol, terminator 4×10 -4 mol, the solvent is methanol, no silane coupling agent is added, the terminator is calcium carbonate, and the viscosity of the polymethoxy-terminated structuring additive is 1.9 cst.

[0054] A preparation method of the above-mentioned polymethoxy-terminated structuring auxiliary agent comprises the following steps: uniformly mixing methyltrimethoxysilane and methanol at room temperature, slowly adding a mixed solution of hydrochloric acid and water, heating to 60°C for hydrolysis and polycondensation reaction for 3 hours, adding calcium carbonate to terminate the reaction to prepare a mixture, further heating to 80°C, distilling to remove the solvent in the mixture, and filtering to obtain the polymethoxy-terminated structuring auxiliary agent.

[0055] Test example 1: The properties of the silicone rubbers prepared in Examples 1 to 7 and Comparative Examples 1 to 6 were tested; The Shore A hardness test method refers to the standard "GB / T 531-2008 Test method for indentation hardness of vulcanized rubber or thermoplastic rubber Part 1: Shore A hardness tester method"; The tensile strength test method refers to the standard "GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber"; The elongation at break test method refers to the standard "GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber"; The tear strength test method refers to the standard "GB / T 529-2009 Determination of tear strength of vulcanized rubber or thermoplastic rubber". The plasticity was tested using a rubber Wei-type plasticity testing machine (High Speed ​​Rail Company); The light transmittance was measured using a transmittance meter YT1020 (Sanens Company); The test results are shown in Table 1; Table 1 Performance test results of silicone rubber As shown in Table 1, it can be seen from the results of Examples 1 to 5 that the elongation at break of the structuring auxiliary agent with the addition of silane coupling agent is significantly increased, the plasticity is significantly reduced, but the transmittance is still greater than 72%. While having a high transmittance, the plasticity is significantly reduced, and the processing performance and storage performance are significantly increased. It can be seen from the results of Examples 6 and 7 that the plasticity of the structuring auxiliary agent without the addition of silane coupling agent is increased, and the transparency is up to 80%, which has extremely high transparency.

[0056] The structuring aid in Comparative Example 1 only uses methoxy silicone oil, and the structuring aid in Comparative Example 2 only uses hydroxy silicone oil. It is found that the transparency of Comparative Example 1 is only 77%, while the transparency of Comparative Example 2 is only 73%. The results of Comparative Example 1, Comparative Example 2 and Example 6 show that the polymethoxy-terminated structuring aid of the present invention has higher transparency than the traditional hydroxy silicone oil and methoxy silicone oil used in the compound rubber.

[0057] In Comparative Example 3, the amount of water was increased (the molar ratio of methyltrimethoxysilane to water was 1:2.2), which promoted the hydrolysis of methyltrimethoxysilane. The viscosity was greater than 20 cst and was used in the rubber compound. The transparency was still high, but the plasticity increased significantly, which was not conducive to processing and storage.

[0058] In Comparative Example 4, the amount of water was reduced (the molar ratio of methyltrimethoxysilane to water was 1:0.2). The hydrolysis of methyltrimethoxysilane was limited, and the viscosity was less than 2 cst. When used in the rubber compound, the transparency was still high, but the plasticity was also significantly increased, which was not conducive to processing and storage.

[0059] Comparative Examples 5 and 6 adjust the viscosity of the polymethoxy-terminated structuring additive by changing the amount of solvent methanol. The products obtained in Comparative Examples 5 and 6 have higher transparency, but the plasticity is still too large, which is not conducive to processing and storage.

[0060] Test example 2: The viscosity and volatile matter of the polymethoxy-terminated structuring additives prepared in Examples 1 to 7 were tested; the viscosity was tested using an annual tester; the volatile matter was tested by heating at 105° C. for 30 minutes; the test results are shown in Table 2; Table 2 Test results Viscosity / cst Volatile matter (105℃×30min) / % Example 1 2 25 Example 2 20 5 Example 3 18 6 Example 4 14 7 Example 5 8.5 10 Example 6 12.5 15 Example 7 17.9 6 Methyltrimethoxysilane 0.8 90 Methoxy silicone oil 3.2 25 As shown in Table 2, the viscosity of the structuring additives of Examples 1 to 7 is 2 to 17.9 cst, and the volatile matter is 5 to 25%. Compared with methyltrimethoxysilane and methoxy silicone oil, the polymethoxy-terminated structuring additive provided by the present invention has high viscosity, low volatile matter, lower waste during application, low risk of combustion and explosion, and higher safety.

[0061] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A polymethoxy-terminated structuring additive, characterized in that: The raw materials include methyltrimethoxysilane, solvent, silane coupling agent, catalyst, water and terminator, wherein the molar ratio of methyltrimethoxysilane to catalyst is 1:

10. -4 ~10 -2 , the catalyst is one of hydrochloric acid, sulfuric acid, nitric acid and acetic acid.

2. The polymethoxy-terminated structuring aid according to claim 1, characterized in that: The molar ratio of methyltrimethoxysilane to solvent is 1:0.5-5; the molar ratio of methyltrimethoxysilane to water is 1:0.5-2; the molar ratio of methyltrimethoxysilane to silane coupling agent is 1:0-0.1; the molar ratio of terminator to catalyst is 1-4:1; the terminator is one of calcium carbonate, calcium oxide and magnesium oxide.

3. The polymethoxy-terminated structuring aid according to claim 1, characterized in that: The solvent is one or more of methanol, ethanol and isopropanol.

4. The polymethoxy-terminated structuring aid according to claim 1, characterized in that: The viscosity of the polymethoxy-terminated structuring additive is 2~20 cst.

5. The polymethoxy-terminated structuring aid according to claim 1, characterized in that: The silane coupling agent is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, isobutyltrimethoxysilane and isobutyltriethoxysilane.

6. A method for preparing the polymethoxy-terminated structuring additive according to any one of claims 1 to 5, characterized in that: The following steps are involved: After methyltrimethoxysilane, silane coupling agent and solvent are uniformly mixed, a catalyst and water mixed solution are added to carry out hydrolysis and polycondensation reaction, a terminator is added to terminate the reaction, and distillation and filtration are carried out to obtain a polymethoxy-terminated structuring auxiliary agent.

7. The preparation method according to claim 6, characterized in that: The temperature of the hydrolysis and polycondensation reaction is 30-60°C.

8. The preparation method according to claim 6 or 7, characterized in that: The hydrolysis and polycondensation reaction time is 3 to 5 h.

9. The preparation method according to claim 6, characterized in that: The distillation temperature is 60-100°C.

10. A highly transparent silicone rubber, characterized in that: The raw materials include: methyl vinyl rubber, white carbon black, a structuring aid and a release agent, wherein the structuring aid includes hydroxy silicone oil and the polymethoxy-terminated structuring aid according to any one of claims 1 to 5.

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