Modified methyl vinyl MQ silicon resin with low hydroxyl content and high vinyl content and preparation method of modified methyl vinyl MQ silicon resin

Abstract

The invention discloses modified methyl vinyl MQ silicon resin with low hydroxyl content and high vinyl content and a preparation method of the modified methyl vinyl MQ silicon resin. The preparation method comprises the following steps: (1) mixing and stirring water, an organic solvent, a catalyst and an end-capping reagent, and heating for reaction; (2) dropwise adding tetraethoxysilane into the mixed solution, and continuously reacting after dropwise adding; (3) after the reaction is finished, adding alkali to neutralize until the pH is 7-9, after the neutralization is finished, adding an extracting agent to extract, separating liquid, and washing with water until the solution is neutral; (4) carrying out vacuum devolatilization on the washed neutral mixture at 80 DEG C for 0.5-1 hour; then dropwise adding an isocyanate solution, keeping the temperature of 80 DEG C to react for 1-2 hours after dropwise adding is completed, and continuously removing the residual solvent to obtain the modified silicon resin powder. According to the invention, isocyanate is added and can react with hydroxyl on the silicon resin to generate carbamate, and the reaction does not need to add an additional catalyst, does not generate byproducts, does not need high temperature and does not cause yellowing of the resin; through the scheme, the silicon hydroxyl content of the silicon resin is effectively reduced, the silicon resin is modified, and the reinforcing effect of the silicon resin is improved.

Description

Technical Field

[0001] The invention relates to the technical field of silicone resin synthesis, and in particular to a low-hydroxyl, high-vinyl content modified methyl vinyl MQ silicone resin and a preparation method thereof. Background Art

[0002] Methyl vinyl MQ silicone resin, as a type of MQ silicone resin, is mainly used for liquid glue reinforcement. The reinforced liquid glue has good strength and does not significantly increase the viscosity of the liquid glue compared to white carbon black reinforcement. It is widely used in LED packaging, silicone leather and other fields. The current problems of vinyl silicone resin mainly include low vinyl content, easy yellowing, high silicon hydroxyl content, and strength needs to be further improved. Regarding the hydroxyl problem of silicone resin, CN 117777446 A discloses a hydroxyl treatment method, which uses alkoxysilanes such as hexamethyldisiloxane, dimethylvinylethoxysilane, tetramethyldisiloxane and diphenylethoxysilane to react with the hydroxyl of silicone resin under acidic conditions to achieve the purpose of reducing the silanol content, which can reduce the hydroxyl from about 5% to below 0.5%. However, in this scheme, high-hydroxy MQ silicone resin: solvent (alkoxysilane): acid catalyst = 1~2:3:0.5~1, a large amount of solvent and acid are used, and a large number of steps (salt washing, alkali washing, water washing, drying, etc.) are required to remove the solvent and acid later, and the process flow is long. CN 117247547 A discloses a synthesis method of vinyl MQ silicone resin with low hydroxyl content, which uses silazane to treat the hydroxyl on the surface of silicone resin, but the reaction produces ammonia and has no effect on improving the reinforcing effect of the silicone resin itself. In addition, there is a method of reducing the hydroxyl by promoting the self-condensation of silanol by high temperature, but when the vinyl content is high, the vinyl is easily detached and yellowing occurs. Summary of the invention

[0003] The present invention aims to provide a low-hydroxyl and high-vinyl content modified methyl vinyl MQ silicone resin and a preparation method thereof, which solves the problem of high hydroxyl content and easy yellowing of the methyl vinyl MQ silicone resin and improves the reinforcing effect of the silicone resin. The technical solution of the present invention is as follows: A method for preparing a low-hydroxyl, high-vinyl content modified methyl vinyl MQ silicone resin, the method comprising the following steps: (1) Mix water, organic solvent, catalyst and end-capping agent, stir and heat to react; (2) adding ethyl orthosilicate dropwise to the mixed solution, and continuing the reaction after the addition is complete; (3) After the reaction is completed, add alkali to neutralize to a pH of 7-9. After neutralization, add an extractant to extract, separate the liquids, and wash with water until neutral; (4) The neutral mixture after water washing is vacuum-desorbed at 80°C for 0.5-1h; then the isocyanate solution is added dropwise, and after the addition is completed, the temperature is maintained at 80°C for 1-2h, and the remaining solvent is continuously removed to obtain a modified silicone resin powder.

[0004] Preferably, the amount of water in step (1) is 30-70% of the amount of tetraethyl orthosilicate; the organic solvent is a mixture of ethanol and xylene, the mass ratio of which is 0.5-1:1; the total amount is 40-60% of the amount of tetraethyl orthosilicate; the catalyst is concentrated hydrochloric acid, the amount of the catalyst is 7%-12% of the amount of tetraethyl silicate; the end-capping agent is a mixture of hexamethyldisiloxane and tetramethyldivinyldisiloxane, the amount ratio of hexamethyldisiloxane to tetramethyldivinyldisiloxane is 0.5-1:1; the total amount is 30%-40% of the amount of tetraethyl orthosilicate; the mixing and stirring time is 10-30 minutes, and then the temperature is raised to 60-75°C for reaction for 0.5-1.5 hours.

[0005] Preferably, in step (2), ethyl orthosilicate is added dropwise to the mixed solution for 0.5-1 h, and after the addition is completed, the temperature is maintained at 65-85° C. for 4-6 h; Preferably, in step (3), the alkali is one of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium bicarbonate and potassium bicarbonate; the extractant is one of hexamethyldisiloxane, toluene and xylene, and the amount used is 50-150% of the amount of ethyl orthosilicate fed. Preferably, the isocyanate solution in step (4) is prepared by dissolving at least one of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate or p-toluenesulfonyl isocyanate in a solvent, the solvent is one of toluene, xylene, DMSO and DMF, the mass ratio of isocyanate to solvent is 1:1-3, and the amount of isocyanate solution is 1-10% of the mass of tetraethyl orthosilicate.

[0006] The beneficial effects of the present invention are: 1. By adding isocyanate, it can react with the hydroxyl group on the silicone resin to form carbamate. This reaction does not require the addition of additional catalysts, does not generate by-products, does not require high temperature, and will not cause the resin to yellow.

[0007] 2. By adding isocyanate, not only the silanol content of silicone resin is effectively reduced, but also the silicone resin is modified, thereby improving the reinforcing effect of silicone resin. DETAILED DESCRIPTION

[0008] The present invention is described in further detail below in conjunction with examples, but embodiments of the present invention are not limited thereto. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art. The test methods for which specific experimental conditions are not specified in the following examples are usually carried out according to conventional experimental conditions or according to the experimental conditions recommended by the manufacturer. Unless otherwise specified, reagents and raw materials used in the present invention can be obtained by commercial means or conventional methods.

[0009] Example 1 At room temperature (25°C), the following isocyanates were added into a flask respectively, and a solvent was added and stirred for 0.5 h to obtain an isocyanate solution. These isocyanate solutions were used as raw materials in the following examples respectively.

[0010] serial number 1 2 3 4 5 6 Isocyanate Type Toluene diisocyanate Isophorone diisocyanate Methylene diphenyl diisocyanate Dicyclohexylmethane diisocyanate Hexamethylene diisocyanate p-Toluenesulfonyl isocyanate Isocyanate dosage 10 10 10 10 10 10 Solvent type Toluene Xylene DMSO DMF Xylene Xylene Solvent dosage 30 10 10 20 20 10 Example 2 (1) Add 70 parts (all parts by mass) of water, 20 parts of ethanol, 40 parts of xylene, 7 parts of concentrated hydrochloric acid, 13 parts of hexamethyldisiloxane and 26 parts of tetramethyldivinyldisiloxane into a reaction kettle, stir at room temperature for 30 minutes, and then raise the temperature to 75°C for reaction for 0.5 hours.

[0011] (2) Add 100 parts of ethyl orthosilicate dropwise into the mixed solution for 0.5 h. After the addition is complete, keep the mixture warm to 65°C and continue the reaction for 6 h.

[0012] (3) After the reaction is completed, sodium carbonate is added to neutralize the pH to 7. After neutralization, 100 parts of xylene are added for extraction, separation, and washing with water until neutral.

[0013] (4) The neutral mixture after washing with water was vacuum-desorbed at 80°C for 1 hour; then 4 parts of the isocyanate solution No. 1 in the example were added dropwise, and after the addition was completed, the temperature was kept at 80°C for 2 hours, and the remaining solvent was further removed to obtain a modified silicone resin powder.

[0014] Example 3 (1) Add 60 parts (all parts by mass) of water, 20 parts of ethanol, 20 parts of xylene, 9 parts of concentrated hydrochloric acid, 12 parts of hexamethyldisiloxane and 22 parts of tetramethyldivinyldisiloxane into a reaction kettle, stir at room temperature for 20 minutes, and then heat to 70°C for reaction for 1 hour.

[0015] (2) Add 100 parts of ethyl orthosilicate dropwise into the mixed solution for 0.75 h. After the addition is complete, keep the mixture warm to 85°C and continue the reaction for 4 h.

[0016] (3) After the reaction is completed, sodium hydroxide is added to neutralize the pH to 8. After neutralization, 500 parts of toluene are added for extraction, separation, and washing with water until neutral.

[0017] (4) The neutral mixture after washing with water was vacuum-desorbed at 80°C for 1 hour; then 1 portion of the isocyanate solution No. 2 in the example was added dropwise, and after the addition was completed, the temperature was kept at 80°C for 2 hours, and the remaining solvent was further removed to obtain a modified silicone resin powder.

[0018] Example 4 (1) Add 50 parts (all parts by mass) of water, 30 parts of ethanol, 30 parts of xylene, 10 parts of concentrated hydrochloric acid, 15 parts of hexamethyldisiloxane and 20 parts of tetramethyldivinyldisiloxane into a reaction kettle, stir at room temperature for 10 minutes, and then heat to 65°C to react for 1.5 hours.

[0019] (2) Add 100 parts of ethyl orthosilicate dropwise into the mixed solution for 1 hour. After the addition is complete, keep the temperature at 75°C and continue the reaction for 5 hours.

[0020] (3) After the reaction is completed, sodium bicarbonate is added to neutralize the pH to 9. After neutralization, 100 parts of hexamethyldisiloxane is added for extraction, separation, and washing with water until neutral.

[0021] (4) The neutral mixture after washing with water was vacuum-desorbed at 80°C for 1 hour; then 2 parts of the isocyanate solution No. 3 in the example were added dropwise, and after the addition was completed, the temperature was kept at 80°C for 2 hours, and the remaining solvent was further removed to obtain a modified silicone resin powder.

[0022] Example 5 (1) Add 40 parts (all parts by mass) of water, 20 parts of ethanol, 30 parts of xylene, 12 parts of concentrated hydrochloric acid, 14 parts of hexamethyldisiloxane and 18 parts of tetramethyldivinyldisiloxane into a reaction kettle, stir at room temperature for 10 minutes, and then heat to 75°C to react for 1 hour.

[0023] (2) Add 100 parts of ethyl orthosilicate dropwise into the mixed solution for 1 hour. After the addition is complete, keep the temperature at 75°C and continue the reaction for 5 hours.

[0024] (3) After the reaction is completed, sodium bicarbonate is added to neutralize the pH to 7. After neutralization, 100 parts of xylene are added for extraction, separation, and washing with water until neutral.

[0025] (4) The neutral mixture after washing with water was vacuum-desorbed at 80°C for 1 hour; then 6 parts of the isocyanate solution No. 4 in the example were added dropwise, and after the addition was completed, the temperature was kept at 80°C for 2 hours, and the remaining solvent was further removed to obtain a modified silicone resin powder.

[0026] Example 6 (1) Add 30 parts (all parts by mass) of water, 20 parts of ethanol, 30 parts of xylene, 9 parts of concentrated hydrochloric acid, 18 parts of hexamethyldisiloxane and 18 parts of tetramethyldivinyldisiloxane into a reaction kettle, stir at room temperature for 10 minutes, and then heat to 75°C to react for 1 hour.

[0027] (2) Add 100 parts of ethyl orthosilicate dropwise into the mixed solution for 0.5 h. After the addition is complete, keep the mixture warm to 65°C and continue the reaction for 5 h.

[0028] (3) After the reaction is completed, sodium bicarbonate is added to neutralize the pH to 7. After neutralization, 100 parts of xylene are added for extraction, separation, and washing with water until neutral.

[0029] (4) The neutral mixture after washing was vacuum-desorbed at 80°C for 0.75h; then 10 parts of the isocyanate solution No. 5 in the example was added dropwise, and after the addition was completed, the temperature was kept at 80°C for 2h, and the remaining solvent was further removed to obtain a modified silicone resin powder.

[0030] Example 7 (1) Add 40 parts (all parts by mass) of water, 20 parts of ethanol, 30 parts of xylene, 10 parts of concentrated hydrochloric acid, 14 parts of hexamethyldisiloxane and 26 parts of tetramethyldivinyldisiloxane into a reaction kettle, stir at room temperature for 30 minutes, and then raise the temperature to 75°C for reaction for 0.5 hours.

[0031] (2) Add 100 parts of ethyl orthosilicate dropwise into the mixed solution for 0.5 h. After the addition is complete, keep the mixture warm to 75°C and continue the reaction for 5 h.

[0032] (3) After the reaction is completed, sodium bicarbonate is added to neutralize the pH to 7. After neutralization, 100 parts of xylene are added for extraction, separation, and washing with water until neutral.

[0033] (4) The neutral mixture after water washing was vacuum degassed at 80°C for 1 hour; then 5 parts of the isocyanate solution No. 6 in the example were added dropwise, and after the addition was completed, the temperature was kept at 80°C for 2 hours, and the remaining solvent was further removed to obtain a modified silicone resin powder.

[0034] Example 8 (1) Add 45 parts (all parts by mass) of water, 20 parts of ethanol, 30 parts of xylene, 9 parts of concentrated hydrochloric acid, 15 parts of hexamethyldisiloxane and 20 parts of tetramethyldivinyldisiloxane into a reaction kettle, stir at room temperature for 10 minutes, and then heat to 75°C for reaction for 1 hour.

[0035] (2) Add 100 parts of ethyl orthosilicate dropwise into the mixed solution for 0.5 h. After the addition is complete, keep the mixture warm to 85°C and continue the reaction for 5 h.

[0036] (3) After the reaction is completed, sodium bicarbonate is added to neutralize the pH to 8. After neutralization, 100 parts of xylene are added for extraction, separation, and washing with water until neutral.

[0037] (4) The neutral mixture after washing was vacuum-desorbed at 80°C for 0.5h; then 8 parts of the isocyanate solution No. 3 in the example were added dropwise, and after the addition was completed, the temperature was kept at 80°C for 2h, and the remaining solvent was further removed to obtain a modified silicone resin powder.

[0038] Comparative Example 1 (1) Add 30 parts (all parts by mass) of water, 20 parts of ethanol, 30 parts of xylene, 9 parts of concentrated hydrochloric acid, 18 parts of hexamethyldisiloxane and 18 parts of tetramethyldivinyldisiloxane into a reaction kettle, stir at room temperature for 10 minutes, and then heat to 75°C to react for 1 hour.

[0039] (2) Add 100 parts of ethyl orthosilicate dropwise into the mixed solution for 0.5 h. After the addition is complete, keep the mixture warm to 65°C and continue the reaction for 5 h.

[0040] (3) After the reaction is completed, sodium bicarbonate is added to neutralize the pH to 7. After neutralization, 100 parts of xylene are added for extraction, separation, and washing with water until neutral.

[0041] (4) The neutral mixture after washing with water was vacuum-desorbed at 80°C for 0.75h; then 10 parts of hexamethyldisilazane were added dropwise, and after the addition was completed, the temperature was kept at 80°C for 2h, and the remaining solvent was further removed to obtain a modified silicone resin powder.

[0042] Comparative Example 2 (1) Add 30 parts (all parts by mass) of water, 20 parts of ethanol, 30 parts of xylene, 9 parts of concentrated hydrochloric acid, 18 parts of hexamethyldisiloxane and 18 parts of tetramethyldivinyldisiloxane into a reaction kettle, stir at room temperature for 10 minutes, and then heat to 75°C to react for 1 hour.

[0043] (2) Add 100 parts of ethyl orthosilicate dropwise into the mixed solution for 0.5 h. After the addition is complete, keep the mixture warm to 65°C and continue the reaction for 5 h.

[0044] (3) After the reaction is completed, sodium bicarbonate is added to neutralize the pH to 7. After neutralization, 100 parts of xylene are added for extraction, separation, and washing with water until neutral.

[0045] (4) The neutral mixture after water washing is vacuum-deionized at 80°C for 0.75h to remove residual water; then the temperature is raised to 160°C to remove the remaining solvent to obtain silicone resin powder.

[0046] Example 9 The silicone resin samples obtained in Examples 2-8 and Comparative Examples 1-2 were tested for vinyl content and silanol content by iodine titration and gas titration, respectively. The appearance was visually inspected. The test results are shown in the following table.

[0047]

[0048] Example 10 Add 80 parts of 10000cp vinyl-terminated silicone oil and 20 parts of 100000cp vinyl-terminated silicone oil to a kneader, add 15 parts of hexamethyldisilazane, knead evenly, add 10 parts of white carbon black in batches, knead for 1 hour, add 30 parts of silicone resin in Examples 2-8 and Comparative Examples 1-2, knead evenly, and remove the base rubber. Add 1PPM of ethynyl cyclohexanol inhibitor and 10ppm of platinum catalyst (based on platinum content); add hydrogen-containing silicone oil at a molar ratio of hydrogen content to vinyl content of 1.15 to obtain liquid silicone rubber. The liquid rubber is vulcanized on a flat vulcanizer at 120°C for 5 minutes to prepare a sheet.

[0049] The liquid glue prepared above was subjected to a tensile strength test according to GB / T 1040.1-2006 and a hardness test according to GB / T 6031-2017; it was coated on the base glue and the middle coating as a silicone leather surface glue (coating thickness 30μm) and subjected to a wear resistance test according to GB / T19089-2012. The specific results are shown in the following table.

[0050] project Hardness (Shore A) Tensile strength (MPa) Wear times Example 2 75 6.22 130,000 damages Example 3 69 6.28 100,000 times damage Example 4 66 6.70 80,000 damages Example 5 66 7.24 90,000 damages Example 6 61 7.37 60,000 damages Example 7 73 6.61 120,000 damages Example 8 74 8.70 150,000 damages Comparative Example 1 58 5.08 40,000 damages Comparative Example 2 55 4.69 30,000 times broken The technical solution of the present invention is explained through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above specific embodiments to be implemented. Any improvements made by technicians in the relevant field based on the present invention, or equivalent replacement of the materials selected by the present invention, etc., fall within the scope of protection of the patent.

Claims

1. A method for preparing a low-hydroxyl, high-vinyl content modified methyl vinyl MQ silicone resin, characterized in that: The method comprises the following steps: (1) Mix water, organic solvent, catalyst and end-capping agent, stir and heat to react; (2) adding ethyl orthosilicate dropwise to the mixed solution, and continuing the reaction after the addition is complete; (3) After the reaction is completed, add alkali to neutralize to a pH of 7-9. After neutralization, add an extractant to extract, separate the liquids, and wash with water until neutral; (4) The neutral mixture after water washing is vacuum-desorbed at 80°C for 0.5-1h; then the isocyanate solution is added dropwise, and after the addition is completed, the temperature is maintained at 80°C for 1-2h, and the remaining solvent is continuously removed to obtain a modified silicone resin powder.

2. The method for preparing the low hydroxyl and high vinyl content modified methyl vinyl MQ silicone resin according to claim 1, characterized in that: The amount of water used in step (1) is 30-70% of ethyl orthosilicate.

3. The method for preparing the low hydroxyl and high vinyl content modified methyl vinyl MQ silicone resin according to claim 1, characterized in that: The organic solvent in step (1) is a mixture of ethanol and xylene, with a mass ratio of 0.5-1:1; the total amount is 40-60% of tetraethyl orthosilicate.

4. The method for preparing the low hydroxyl and high vinyl content modified methyl vinyl MQ silicone resin according to claim 1, characterized in that: The catalyst in step (1) is concentrated hydrochloric acid, and the amount of the catalyst used is 7%-12% of the amount of tetraethyl silicate used.

5. The method for preparing the low hydroxyl and high vinyl content modified methyl vinyl MQ silicone resin according to claim 1, characterized in that: The end-capping agent in step (1) is a mixture of hexamethyldisiloxane and tetramethyldivinyldisiloxane, the dosage ratio of hexamethyldisiloxane to tetramethyldivinyldisiloxane is 0.5-1:1; the total dosage is 30%-40% of the dosage of tetraethyl orthosilicate.

6. The method for preparing the low hydroxyl and high vinyl content modified methyl vinyl MQ silicone resin according to claim 1, characterized in that: In the step (1), the mixture is mixed and stirred for 10-30 minutes, and then the temperature is raised to 60-75° C. and reacted for 0.5-1.5 hours.

7. The method for preparing the low hydroxyl and high vinyl content modified methyl vinyl MQ silicone resin according to claim 1, characterized in that: In the step (2), ethyl orthosilicate is added dropwise to the mixed solution for 0.5-1 h. After the addition is completed, the temperature is maintained at 65-85° C. for 4-6 h.

8. The method for preparing the low hydroxyl and high vinyl content modified methyl vinyl MQ silicone resin according to claim 1, characterized in that: In the step (4), the isocyanate solution is prepared by dissolving at least one of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate or p-toluenesulfonyl isocyanate in a solvent, wherein the solvent is one of toluene, xylene, DMSO and DMF, the mass ratio of isocyanate to solvent is 1:1-3, and the amount of isocyanate solution used is 1-10% of the mass of tetraethyl orthosilicate.

9. The method for preparing the low hydroxyl and high vinyl content modified methyl vinyl MQ silicone resin according to claim 1, characterized in that: In the step (3), the base is one of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium bicarbonate and potassium bicarbonate.

10. The method for preparing the low hydroxyl and high vinyl content modified methyl vinyl MQ silicone resin according to claim 1, characterized in that: In the step (3), the extractant is one of hexamethyldisiloxane, toluene and xylene, and the amount used is 50-150% of the amount of ethyl orthosilicate fed.

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