High-dispersity and low-thermal-weight-loss vinyl MQ silicon resin and preparation method thereof

Abstract

The invention discloses vinyl MQ silicon resin with high dispersibility and low thermal weight loss and a preparation method thereof, and the preparation method comprises the following steps: (1) mixing and stirring water, an organic solvent, a catalyst and an end-capping reagent for 30 min, then heating to 60-75 DEG C, and reacting for 0.5-1.5 h; (2) cooling to 30-45 DEG C, dropwise adding 100 parts of tetraethoxysilane into the mixed solution for 0.5-1 hour, and continuously keeping the temperature at 30-45 DEG C to react for 0.5-1 hour after dropwise adding is completed; (3) raising the temperature to 60-80 DEG C, and continuously reacting for 4-6 hours; (4) adding alkali for neutralization after the reaction is finished, adding an extracting agent for extraction after the neutralization is finished, separating liquid, and washing to be neutral; (5) gradually heating the washed neutral mixture to 120 DEG C, and removing residual water; and heating to 150 DEG C, and removing the solvent in vacuum to obtain the powdery silicon resin. By controlling the temperature of different reaction stages, the hydrolysis rate and the polycondensation rate of different reactants are controlled, and the dispersity and the thermal stability of the final product are improved; the product is high in hydrolytic condensation degree, low in final alkoxy and hydroxyl content and suitable for reinforcement of addition type liquid glue.

Description

Technical Field

[0001] The invention relates to the technical field of silicone resin synthesis, and in particular to a high-dispersibility, low-thermal-weight-loss vinyl MQ silicone resin and a preparation method thereof. Background Art

[0002] MQ silicone resin is a nonlinear organic polysiloxane, which is composed of a tetrafunctional siloxane chain (Q unit, SiO 4 / 2 ) and a monofunctional siloxane link (abbreviated as M unit, R1R2R3SiO0.5). MQ silicone resin can be divided into methyl MQ silicone resin, methyl vinyl MQ silicone resin, vinyl MQ silicone resin, hydrogen-containing MQ silicone resin, etc. according to the different M units. In addition to the difference in M ​​units, the MQ ratio is also an important parameter that affects the performance and application area of ​​MQ silicone resin. Generally speaking, with the increase of the MQ ratio, the softening point of MQ silicone resin gradually decreases, and it changes from solid powder to liquid at room temperature and pressure, and its properties gradually change from inorganic polymer to organic polymer. The ratio of M unit to Q unit in commonly used MQ silicone resin is usually between 0.6-1.2. The properties of MQ silicone resin are between those of ordinary inorganic and organic polymer compounds. It has properties that are difficult for ordinary resins to achieve, such as high temperature resistance, water repellency and chemical resistance. In addition, it has excellent electrical insulation properties, mechanical properties, heat resistance, flexibility, film-forming properties and adhesion. It has high industrial application value and is widely used in liquid silicone rubber reinforcing fillers, tackifiers, pressure-sensitive adhesives, surface treatment agents, personal care product additives and other fields.

[0003] Methyl vinyl MQ, as a type of MQ silicone resin, is mainly used in liquid adhesive reinforcement and pressure-sensitive adhesive, and has high requirements for the dispersibility and thermal stability of silicone resin. In the prior art, most of the focus is on the preparation of conventional methyl vinyl MQ silicone resin, mainly the research on feeding methods, raw materials, catalysts, etc., to improve the controllability of the reaction process, improve the yield, etc.; there are few studies on the application properties of silicone resin, such as solubility in silicone oil, heat resistance, etc. For example, CN102775612A discloses a method for synthesizing methyl vinyl MQ silicone resin, using dimethyl vinyl ethoxysilane as the source of M chain segments, with an efficiency increase of 10% and a yield increase of 3-5%. CN106084230A discloses a method for preparing a silicone resin with low thermal weight loss, low refractive index and narrow molecular weight distribution. The advantages of the technical solution mentioned in the invention are that it is not easy to gel, the amount of solvent used is small, the double head utilization rate is high, the structure is easy to control and it is environmentally friendly. It mainly focuses on the controllability of the preparation process and the reaction yield. Although it is mentioned that the residual amount of the prepared methyl vinyl silicone resin at 600°C is 61.95%, no corresponding research has been conducted. At the same time, high-temperature coatings, high-temperature adhesives, high-temperature sealing gaskets, high-temperature resistant electronic component packaging and other fields have higher requirements for resin thermal weight loss; and the patent does not provide solubility and dispersibility data of silicone resin in silicone oil, which has certain limitations in guiding the use of vinyl MQ silicone resin in the field of liquid glue reinforcement, especially in the field of high-temperature liquid glue reinforcement. Summary of the invention

[0004] The invention aims to provide a high-dispersibility, low-thermal-weight-loss vinyl MQ silicone resin and a preparation method thereof, which solves the problems of high thermal-weight-loss and difficulty in dispersion of methyl vinyl MQ silicone resin. The technical solution of the present invention is as follows: A method for preparing a high-dispersibility, low-weight-loss-on-heat 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) Cooling down, adding ethyl orthosilicate dropwise to the mixed solution, and continuing the reaction after the addition is complete; (3) Raise the temperature and continue the reaction; (4) After the reaction is completed, add alkali to neutralize the pH to 7-9. After neutralization, add an extractant to extract, separate the liquids, and wash with water until neutral; (5) The neutral mixture after washing with water is gradually heated to 120°C to remove residual water; then the temperature is raised to 150°C to remove the solvent in vacuo to obtain a powdered silicone resin.

[0005] Preferably, the amount of water in step (1) is 30-70% of ethyl orthosilicate.

[0006] Preferably, the organic solvent in step (1) is one or a mixture of several lower aliphatic alcohols, specifically methanol, ethanol, isopropanol or a mixture thereof, and the amount used is 25-60% of ethyl orthosilicate. Preferably, the catalyst in step (1) is one of concentrated sulfuric acid, concentrated hydrochloric acid, concentrated nitric acid, benzoic acid, benzenesulfonic acid and heteropoly acid, and the amount of the catalyst is 5%-15% of the amount of tetraethyl silicate. Preferably, the end-capping agent in step (1) is a mixture of a methyl end-capping agent and a vinyl end-capping agent, and the dosage ratio of the methyl end-capping agent to the vinyl end-capping agent is (1-20):1; the total dosage is 25%-60% of the dosage of tetraethyl orthosilicate.

[0007] Further preferably, the methyl end-capping agent is one of hexamethyldisiloxane, trimethylmethoxysilane, trimethylchlorosilane or a mixture thereof; the vinyl end-capping agent is one or more of vinyl double end-capping (tetramethyldivinyldisiloxane), vinyl single end-capping (dimethylvinylethoxysilane), trivinylethoxysilane. Preferably, in step (1), the mixture is mixed and stirred for 20-35 minutes, and then the temperature is raised to 60-75° C. and reacted for 0.5-1.5 hours.

[0008] Preferably, in step (2), the temperature is lowered to 30-45°C, and ethyl orthosilicate is added dropwise to the mixed solution for 0.5-1h. After the addition is completed, the temperature is maintained at 30-45°C for 0.5-1h. In step (3), the temperature is raised to 60-80°C and the reaction is continued for 4-6 hours; In step (5), the neutral mixture after washing with water is gradually heated to 120°C, and then heated to 150°C to remove the solvent in vacuo.

[0009] Preferably, in step (3), the base is one of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium bicarbonate and potassium bicarbonate. Preferably, in step (3), the extractant is one or two of hexamethyldisiloxane, benzene, toluene and xylene, and the amount used is 50-150% of the amount of ethyl orthosilicate fed. The beneficial effects of the present invention are: 1. By controlling the temperature at different reaction stages, the hydrolysis rate and polycondensation rate of different reactants can be controlled to improve the dispersibility and thermal stability of the final product.

[0010] 2. By controlling the reaction temperature at different stages, the product has a high degree of hydrolysis and condensation, and the final alkoxy and hydroxyl content of the product is low, which is suitable for addition type liquid adhesive reinforcement.

[0011] 3. Through the joint control of the feeding (dropping of ethyl orthosilicate) speed and the temperature during the feeding stage, the hydrolysis of ethyl orthosilicate and the condensation balance with the end-capping agent can be effectively controlled to improve the dispersibility and thermal stability of silicone resin. DETAILED DESCRIPTION

[0012] 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.

[0013] Normal temperature refers to the ambient temperature without heating or cooling operation, which is 10-30℃.

[0014] Example 1 (1) Add 70 parts (all parts by mass) of water, 25 parts of methanol, 15 parts of concentrated hydrochloric acid, 40 parts of hexamethyldisiloxane and 2 parts of vinyl double-capped (tetramethyldivinyldisiloxane) into a reaction kettle, stir at room temperature for 30 minutes, and then heat to 75°C for reaction for 0.5 hours.

[0015] (2) Cool the mixture to 30°C and add 100 parts of ethyl orthosilicate dropwise to the mixture for 0.5 h. After the addition is complete, continue to maintain the temperature at 30°C for 1 h.

[0016] (3) Raise the temperature to 60°C and continue the reaction for 5 hours.

[0017] (4) 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.

[0018] (5) The neutral mixture after washing with water is gradually heated to 120°C to remove residual water; then the temperature is raised to 150°C to remove the solvent in vacuo to obtain a powdered silicone resin.

[0019] Example 2 (1) Add 60 parts of water, 35 parts of ethanol, 12 parts of benzoic acid, 45 parts of trimethylmethoxysilane and 3 parts of vinyl monocapping agent (dimethylvinylethoxysilane) into a reactor, stir at room temperature for 30 minutes, and then heat to 70°C for reaction for 1 hour.

[0020] (2) Cool the mixture to 40°C and add 100 parts of ethyl orthosilicate dropwise to the mixture for 0.75 h. After the addition is complete, continue to maintain the temperature at 40°C for 1 h.

[0021] (3) Raise the temperature to 70°C and continue the reaction for 6 hours.

[0022] (4) After the reaction is completed, sodium bicarbonate is added to neutralize the pH to 7. After neutralization, 50 parts of benzene is added for extraction, separation, and washing with water until neutral.

[0023] (5) The neutral mixture after washing with water is gradually heated to 120°C to remove residual water; then the temperature is raised to 150°C to remove the solvent in vacuo to obtain a powdered silicone resin.

[0024] Example 3 (1) Add 50 parts of water, 45 parts of ethanol, 10 parts of concentrated nitric acid, 25 parts of trimethylmethoxysilane and 5 parts of vinyl double-capped (tetramethyldivinyldisiloxane) into a reactor, stir at room temperature for 30 minutes, and then raise the temperature to 65°C for reaction for 1.5 hours.

[0025] (2) Cool the mixture to 45°C and add 100 parts of ethyl orthosilicate dropwise to the mixture for 1 hour. After the addition is complete, continue to maintain the temperature at 45°C for 0.5 hour.

[0026] (3) Raise the temperature to 78°C and continue the reaction for 6 hours.

[0027] (4) After the reaction is completed, sodium bicarbonate is added to neutralize the pH to 8. After neutralization, 150 parts of MM (hexamethyldisiloxane) is added for extraction, separation, and washing with water until neutral.

[0028] (5) The neutral mixture after washing with water is gradually heated to 120°C to remove residual water; then the temperature is raised to 150°C to remove the solvent in vacuo to obtain a powdered silicone resin.

[0029] Example 4 (1) Add 40 parts of water, 50 parts of isopropanol, 5 parts of concentrated sulfuric acid, 12.5 parts of hexamethyldisiloxane and 12.5 parts of tetramethyldivinyldisiloxane into a reaction kettle, stir at room temperature for 30 minutes, and then heat to 65°C for reaction for 1 hour.

[0030] (2) Cool the mixture to 35°C and add 100 parts of ethyl orthosilicate dropwise to the mixture for 0.5 h. After the addition is complete, continue to maintain the temperature at 35°C for 1 h.

[0031] (3) Raise the temperature to 80°C and continue the reaction for 5 hours.

[0032] (4) After the reaction is completed, sodium bicarbonate is added to neutralize the pH to 9. After neutralization, 125 parts of xylene are added for extraction, separation, and washing with water until neutral.

[0033] (5) The neutral mixture after washing with water is gradually heated to 120°C to remove residual water; then the temperature is raised to 150°C to remove the solvent in vacuo to obtain a powdered silicone resin.

[0034] Example 5 (1) Add 30 parts of water, 20 parts of methanol, 40 parts of isopropanol, 5 parts of concentrated hydrochloric acid, 15 parts of trimethylchlorosilane and 10 parts of tetramethyldivinyldisiloxane into a reactor, stir at room temperature for 30 minutes, and then heat to 70°C and react for 0.5 hours.

[0035] (2) Cool the mixture to 30°C and add 100 parts of ethyl orthosilicate dropwise to the mixture for 1 hour. After the addition is complete, continue to maintain the temperature at 30°C for 1 hour.

[0036] (3) Raise the temperature to 70°C and continue the reaction for 4 hours.

[0037] (4) After the reaction is completed, sodium bicarbonate is added to neutralize the pH to 7. After neutralization, 100 parts of toluene are added for extraction, separation, and washing with water until neutral.

[0038] (5) The neutral mixture after washing with water is gradually heated to 120°C to remove residual water; then the temperature is raised to 150°C to remove the solvent in vacuo to obtain a powdered silicone resin.

[0039] Comparative Example 1 In a four-necked bottle, 1.60g of concentrated sulfuric acid, 17.00g of vinyl double-capped (tetramethyldivinyldisiloxane), 46.08Gmm (hexamethyldisiloxane), 19.10g of ethanol and 3.00g of water were added to the bottle, and the mixture was reacted at a speed of 300 rpm and 25°C for 1 hour. After the reaction was completed, 50.40g of water and 208.33g of ethyl orthosilicate were added dropwise at room temperature. The temperature in the system was controlled at 40°C. After the addition was completed, the mixture was reacted at 70°C for 2 hours, and then the ethanol in the system was evaporated at 80°C. Then, 123.10g of toluene and an appropriate amount of NaHCO3 were added to adjust the pH of the system to 9, and the mixture was reacted at 90°C for 1 hour. Then, the mixture was heated to 120°C to evaporate the remaining ethanol and water in the system, and finally, the temperature was lowered, acid was added for neutralization, and the mixture was washed with water until the pH of the system was 6. The toluene in the system was evaporated at 120°C to obtain methylvinyl MQ silicone resin.

[0040] Example 6 100 parts of MQ silicone resin (powdered silicone resin) prepared in Examples 1-5 and Comparative Example 1 and an equal mass of vinyl silicone oil (terminated vinyl silicone oil, viscosity 350 cs) were mixed evenly, dispersed at 2500 r / min in a high-speed disperser for 30 minutes, vacuum degassed, and the dissolution and dispersion of the silicone resin was observed.

[0041] Table 1

[0042] The MQ silicone resins prepared in Examples 1-5 and Comparative Example 1 were subjected to thermogravimetric analysis, respectively, with a heating rate of 20°C / min, a test temperature of 30-800°C, and a nitrogen atmosphere. The mass loss was as follows: Table 2

[0043] The MQ silicone resins prepared in Examples 1-5 and Comparative Example 1 were subjected to NMR silicon spectrum analysis, and the results are shown in Table 3.

[0044] Table 3

[0045] It can be seen from Tables 1-3 that the vinyl MQ silicone resin prepared by this scheme can be dissolved in vinyl silicone oil in equal mass, and the viscosity of the silicone oil can be increased without significantly increasing through regulation, which is conducive to the preparation of low-viscosity liquid silicone rubber; at the same time, the thermal weight loss at 800°C is low, which is suitable for high temperature resistant scenarios.

[0046] Example 6 is based on Example 1, with other details unchanged, except for step 2) the dropping time, with other details unchanged.

[0047] Example 6-1: Step 2) Addition time: 15 min; Example 6-2: Step 2) Addition time: 45 min; Example 6-3: Step 2) Addition time: 1 h; Example 6-4: Step 2) Addition time: 1.5 h.

[0048] 100 parts of MQ silicone resin prepared in Example 6-1-6-4 and an equal mass of vinyl silicone oil (terminated vinyl silicone oil, viscosity 350 cs) were mixed evenly, dispersed at 2500 r / min in a high-speed disperser for 30 minutes, and vacuum degassed to observe the dissolution and dispersion of the silicone resin.

[0049] Table 4 Example 1 Example 6-1 Example 6-2 Example 6-3 Example 6-4 Dissolution and dispersion Dissolve Partially dissolved Dissolve Dissolve Partially dissolved Dissolved state Colorless and transparent Particle suspension Colorless and transparent Colorless and transparent Particle suspension Viscosity after dissolution / cs 5545 / 5428 6859 / The MQ silicone resins prepared in Examples 6-1 to 6-4 were subjected to thermogravimetric analysis, respectively, with a heating rate of 20°C / min, a test temperature of 30-800°C, and a nitrogen atmosphere. The mass loss was as follows: Table 5 Example 1 Example 6-1 Example 6-2 Example 6-3 Example 6-4 Quality loss / % 39.35 42.24 34.66 37.43 38.25 The MQ silicone resin prepared in Example 6-1-6-4 was subjected to NMR silicon spectrum analysis. The results are shown in Table 6.

[0050] Table 6 Example 1 Example 6-1 Example 6-2 Example 6-3 Example 6-4 Si-OH 0.04% 0.04% 0.05% 0.05% 0.05% <![CDATA[Si-OCH2CH3]]> 1.0% 1.5% 0.9% 0.8% 0.8% It can be seen from Table 1-3 that the solubility and thermal weight loss of vinyl MQ silicone resin can be improved through the effective coordination of feeding temperature and feeding time. By adjusting the feeding time to 0.5-1h, the silicone resin can ensure good solubility in silicone oil.

[0051] 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 high-dispersibility, low-weight-loss-on-heat 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) Cooling down, adding ethyl orthosilicate dropwise to the mixed solution, and continuing the reaction after the addition is complete; (3) Raise the temperature and continue the reaction; (4) 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; (5) Gradually heating the neutral mixture after washing to 120°C to remove residual water; Then the temperature was raised to 150°C and the solvent was removed in vacuo to obtain a powdered silicone resin.

2. The method for preparing the high-dispersibility, low-weight-loss-on-heat 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 high-dispersibility, low-weight-loss-on-heat vinyl MQ silicone resin according to claim 1, characterized in that: The organic solvent in step (1) is one or a mixture of several lower aliphatic alcohols, specifically methanol, ethanol, isopropanol or a mixture thereof, and the amount used is 25-60% of ethyl orthosilicate.

4. The method for preparing the high-dispersibility, low-weight-loss-on-heat vinyl MQ silicone resin according to claim 1, characterized in that: The catalyst in step (1) is one of concentrated sulfuric acid, concentrated hydrochloric acid, concentrated nitric acid, benzoic acid, benzenesulfonic acid and heteropoly acid, and the amount of the catalyst is 5%-15% of the amount of tetraethyl silicate.

5. The method for preparing the high-dispersibility, low-weight-loss-on-heat vinyl MQ silicone resin according to claim 1, characterized in that: The end-capping agent in step (1) is a mixture of a methyl end-capping agent and a vinyl end-capping agent, and the dosage ratio of the methyl end-capping agent to the vinyl end-capping agent is (1-20):1; the total dosage is 25%-60% of the dosage of tetraethyl orthosilicate.

6. The method for preparing the high-dispersibility, low-weight-loss-on-heat vinyl MQ silicone resin according to claim 5, characterized in that: The methyl end-capping agent is one of hexamethyldisiloxane, trimethylmethoxysilane, trimethylchlorosilane or a mixture thereof; the vinyl end-capping agent is one or more of vinyl double-end capping (tetramethyldivinyldisiloxane), vinyl single-end capping (dimethylvinylethoxysilane) and trivinylethoxysilane.

7. The method for preparing the high-dispersibility, low-weight-loss-on-heat vinyl MQ silicone resin according to claim 1, characterized in that: In the step (1), the mixture is stirred for 20-35 minutes, and then the temperature is raised to 60-75° C. and reacted for 0.5-1.5 hours.

8. The method for preparing the high-dispersibility, low-weight-loss-on-heat vinyl MQ silicone resin according to claim 1, characterized in that: In the step (2), the temperature is lowered to 30-45°C, and ethyl orthosilicate is added dropwise to the mixed solution for 0.5-1h. After the addition is completed, the temperature is maintained at 30-45°C for reaction for 0.5-1h. In the step (3), the temperature is raised to 60-80°C and the reaction is continued for 4-6h. In step (5), the neutral mixture after washing with water is gradually heated to 120°C, and then heated to 150°C to remove the solvent in vacuo.

9. The method for preparing the high-dispersibility, low-weight-loss-on-heat 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 high-dispersibility, low-weight-loss-on-heat vinyl MQ silicone resin according to claim 1, characterized in that: In the step (3), the extractant is one or two of hexamethyldisiloxane, benzene, toluene and xylene, and the amount used is 50-150% of the amount of tetraethyl orthosilicate fed.

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