Method for preparing methyl silicone oil containing side chain monovinyl and application

Abstract

The invention belongs to the field of organic silicon synthesis, and discloses a preparation method of methyl silicone oil containing side chain monovinyl, which is applied to preparation of liquid silicone rubber. The preparation method comprises the following steps: carrying out condensation polymerization on alpha, omega-hydroxyl polydimethylsiloxane and alpha, omega-hydroxyl polymethylvinyl siloxane under the action of a linear phosphonitrile chloride catalyst, then adding hexamethyldisiloxane for chain scission equilibrium, adding a terminator for neutralization reaction after the reaction is finished, and carrying out condensation polymerization to obtain the polydimethylsiloxane. And removing the low content of the obtained silicone oil intermediate to obtain the monovinyl methyl silicone oil product. The silicone oil is used for preparing the liquid silicone rubber, and the obtained liquid silicone rubber has good mechanical properties and does not produce oil after being stored for 3 months.

Description

Technical Field

[0001] The invention belongs to the technical field of organic silicon, and in particular relates to the synthesis and application of methyl vinyl silicone oil. Background Art

[0002] As one of the four major categories of silicone, silicone oil is the most widely used silicone product. Silicone oil is usually divided into methyl silicone oil, vinyl silicone oil, phenyl silicone oil, etc. Methyl silicone oil is the most common type of silicone oil, with good chemical stability, lubricity, heat resistance, and electrical insulation. Vinyl silicone oil is a product in which some of the methyl groups in methyl silicone oil are replaced by vinyl groups. It has excellent lubricity, high and low temperature resistance, and compatibility, and is mainly used as an additive for addition-type silicone rubber. Methyl silicone oil can be used in silicone rubber to increase the softness, elasticity, low-temperature resistance, and processing properties of silicone rubber, improve the internal micropores and defects of the rubber, and enhance its resistance to compression deformation and tensile strength. It is used in industries such as mold manufacturing. Adding methyl silicone oil to the base rubber stage can improve the fluidity and mixing uniformity of the material, thereby reducing the generation of bubbles. By adjusting the proportion of methyl silicone oil, silicone rubber products with a wide range of hardness can be produced to meet the needs of different industries and application scenarios. In order to make silicone rubber products more resilient and flexible, silicone oil is often added as a release agent or diluent. However, if methyl silicone oil is added in excess, it will separate from the base rubber and seep out during the subsequent application of the silicone rubber, causing serious oil leakage on the surface and affecting its use.

[0003] Vinyl-containing polydimethylsiloxane, particularly in the preparation of addition-type silicone rubber, can participate in the hydrosilylation reaction, reducing the oiling phenomenon seen in pure methyl silicone oils and increasing crosslinking density and rubber strength. However, excessive vinyl content can lead to high crosslinking density and a harder silicone rubber, resulting in poor performance in some mold applications.

[0004] The present invention uses methylvinyldichlorosilane to prepare α,ω-hydroxypolymethylvinylsiloxane as a raw material, and α,ω-hydroxypolydimethylsiloxane under the action of a linear chlorophosphazene catalyst to prepare a methyl silicone oil containing a vinyl group in the side chain. The silicone oil with this structure mainly has the properties and application performance of methyl silicone oil. During the preparation of silicone rubber, the vinyl group participates in the reaction and is bonded to the silicone rubber through chemical bonds. This can solve the problem of oil leakage when methyl silicone oil is used in silicone rubber, while also having the advantage of methyl silicone oil in improving the flexibility of liquid silicone rubber. Summary of the Invention

[0005] In view of the above content, the purpose of the present invention is to provide a method for synthesizing methyl silicone oil containing a vinyl group in the side chain, which has a simple preparation process and can be applied to the preparation of silicone rubber.

[0006] The present invention is achieved through the following technical solutions: (1) Methylvinyldichlorosilane and dimethyldichlorosilicone oil are mixed evenly at 25-35°C and added dropwise to aqueous ammonia for hydrolysis reaction to obtain a mixture of crude vinyl hydroxy silicone oil and aqueous ammonium chloride solution; then, α,ω-hydroxypolymethylvinylsiloxane is obtained after oil-water separation, decolorization and decolorization.

[0007] (2) Mixing α,ω-hydroxy polydimethylsiloxane and α,ω-hydroxy polymethylvinylsiloxane uniformly at 50-120°C, vacuum dehydration, adding linear phosphazene chloride catalyst, vacuum polycondensation reaction, adding hexamethyldisiloxane for equilibrium, adding terminator for neutralization reaction after the reaction, and obtaining silicone oil intermediate; (3) The intermediate is desulfurized at 180-200°C to obtain the finished silicone oil.

[0008] (4) A method for preparing liquid silicone rubber: vinyl-terminated silicone oil, hexamethyldisilazane, water, hydrogenated silicone oil, silicone oil, and vinylsilazane are stirred and mixed, and then white carbon black is added. The mixture is heated to 160-170°C and stirred for reaction for 3-4 hours. The mixture is vacuumed and reacted for 1-2 hours. The vinyl-terminated silicone oil is then added and diluted evenly. The mixture is reacted under vacuum for 1-2 hours to degas. The mixture is poured into a mold and cured and vulcanized to obtain liquid silicone rubber.

[0009] In the step (1), the ratio of methylvinyldichlorosilane to dimethyldichlorosilicone oil is 1:5 wt%-25wt% (or understood as a mass ratio of 100:5-25), the concentration of ammonia water is 5-9wt%, and the final product obtained is α,ω-hydroxypolymethylvinylsiloxane with a viscosity of 20-40mm 2 / s, vinyl content is 2.5wt%-6wt%. Preferably, the ratio of methylvinyldichlorosilane to dimethyldichlorosilicone oil is 1:8wt%, and the obtained α,ω-hydroxypolymethylvinylsiloxane has a viscosity of 30mm 2 / s, vinyl content is 4%. The structural formula is as follows: n=1-3, m=5-20.

[0010] In the step (1), the reaction conditions are as follows: the hydrolysis temperature is 25-35°C, preferably 30°C; the decolorization temperature is 50-100°C, preferably 80°C; and activated carbon treatment is used for decolorization.

[0011] In the step (2), the raw material α, ω-hydroxy polydimethylsiloxane has a viscosity of 20-200 mm 2 / s, volatile matter is 1%-3%.

[0012] Preferred viscosity 100mm 2 / s, volatile matter is 2%.

[0013] In the step (2), the ratio of α,ω-hydroxypolydimethylsiloxane, α,ω-hydroxypolymethylvinylsiloxane and hexamethyldisiloxane is 1:5wt%-25wt%:1.8wt%-10wt% (or understood as a mass ratio of 100:5-25:1.8-10).

[0014] In the step (2), the catalyst is a linear phosphazene chloride solution, the addition amount is 5-8ppm, and the solvent is 10-100mm 2 / s low viscosity methyl silicone oil, toluene, ethyl acetate, acetone, etc., with a concentration of 1wt%-5wt%, preferably 2wt% toluene solution.

[0015] In step (2), the terminator is an alkaline substance, such as triethylamine, tripropylamine, diisopropylamine, hexamethyldisilazane, butyl lithium or a combination thereof, preferably triethylamine; the amount added is 1-3 times the mass of the catalyst, preferably 1.5 times.

[0016] In step (2), the reaction is carried out under vacuum conditions, with the vacuum degree maintained at 1-50 mbar. After the terminator is added, the reaction is carried out under normal pressure.

[0017] The polycondensation and equilibrium reactions are carried out under vacuum conditions, maintaining a vacuum degree of less than 50 mbar. After the terminator is added, the reaction is carried out under normal pressure.

[0018] In step (2), the vacuum polycondensation reaction temperature is 50-120°C, and the polycondensation time is 8-12 hours. The temperature at which the terminator is added is the polymerization temperature, and the termination time is 0.5-2 hours. Preferably, the reaction temperature is 100°C for 10 hours, and the neutralization time is 0.5 hours.

[0019] In the step (2), the volatile matter of the obtained silicone oil intermediate is 1%-3% and the viscosity is 35-350mm 2 / s.

[0020] In step (2), the desulfurization temperature is 180-200°C and the desulfurization time is 2-5 hours, preferably 200°C for 3 hours.

[0021] In the step (3), the viscosity of the silicone oil product is 35-350mm 2 / s, volatile matter is 0.1%-0.7%, and vinyl content is 0.2%-0.8%.

[0022] In some specific cases, the preparation method of the liquid silicone rubber includes the following steps: Take 500g of 60,000mm 2 / s of vinyl-terminated silicone oil, add 3-6wt% hexamethyldisilazane, 1.0-1.8wt% water, 2-4wt% hydrogenated silicone oil, 3-8wt% methyl silicone oil containing side chain monovinyl, 0.1-0.5wt% vinylsilazane, mix well in a planetary mixer, add 20-30wt% white carbon black in batches, heat to 170℃ and stir for 4 hours, vacuum and react for 2 hours. Then add the remaining 500g of 60,000mm 2 The vinyl-terminated silicone oil with a concentration of 100 μg / s was uniformly diluted and reacted under vacuum for 2 hours to degas. The mixture was poured into a mold and cured at 160°C for 20 minutes, followed by vulcanization at 200°C for 4 hours to obtain liquid silicone rubber.

[0023] The method of the present invention has many excellent technical effects, including: (1) The α,ω-hydroxypolymethylvinylsiloxane prepared with methylvinylchlorosilane as raw material has the advantages of low raw material cost, simple reaction, low environmental protection treatment cost, and obvious overall economic advantages; the obtained α,ω-hydroxypolymethylvinylsiloxane product has controllable viscosity and controllable vinyl content.

[0024] (2) Utilizing the ultra-high activity of linear phosphonitrile chloride catalysts for chain scission rearrangement, the polycondensation reaction of hydroxysiloxanes is catalyzed at extremely low dosages. This allows for a one-step polycondensation chain scission rearrangement, resulting in simple steps, high reaction conversion rates, and significant cost savings. Furthermore, the reaction does not produce a large amount of low-volatile substances, which reduces the difficulty of the desulfurization process, saves energy costs, and simplifies post-processing. The resulting silicone oil has a uniform molecular chain distribution and a low silanol content.

[0025] (3) The monovinylmethyl silicone oil prepared by this method can be used to prepare liquid silicone rubber, which can reduce the hardness of liquid silicone rubber, increase the flexibility of liquid silicone rubber, and improve the processing performance. It can be used in the mold manufacturing industry and has high stability in subsequent processing and use without oil leakage. DETAILED DESCRIPTION

[0026] Example 1 Take a 2L three-necked flask, add 100 grams of methyldichlorosilane and 8 grams of methylvinyldichlorosilane to the reaction bottle, mix them evenly, and add them dropwise to 1000 grams of 9% ammonia solution at room temperature for hydrolysis reaction. Balance for 10 minutes after the addition is completed. After the reaction is completed, use a separatory funnel to separate the oil and water to obtain a crude α, ω-hydroxypolymethylvinylsiloxane. Heat the crude product to 80°C to remove water and low molecular weight compounds, then add activated carbon for adsorption and decolorization. After filtration, the finished α, ω-hydroxypolymethylvinylsiloxane is obtained. The viscosity is tested to be 30mm 2 / s, vinyl content is 4%, silanol content is 6%. Its structural formula is: n=1-3, m=5-20.

[0027] Example 2 Take a 2L three-necked flask, add 1000 grams of α, ω-hydroxy polydimethylsiloxane and 140 grams of α, ω-hydroxy polymethylvinylsiloxane (prepared in Example 1) into the reaction flask, heat to 70°C, and stir under vacuum for 30 minutes. Then break the vacuum, add 0.342 grams of linear chlorophosphazene toluene solution (2wt%), vacuum the reaction, and raise the temperature to 100°C. Stir for 10 minutes, the reaction will quickly become viscous, then add 48 grams of hexamethyldisiloxane, stir the reaction at normal pressure for 30 minutes, and then vacuum the reaction at 10mbar for 10 hours. After the reaction is completed, add 0.513 grams of triethylamine-toluene solution (2wt%) to terminate the reaction and stir at normal pressure for 30 minutes. A silicone oil intermediate is obtained with a volatile matter of 4.2% and a viscosity of 89.2mm 2 / s. The temperature was raised to 200℃ and vacuum was applied to remove low-volatile substances for 3 hours to obtain the final silicone oil product with a viscosity of 101.5mm 2 / s, volatile matter 0.52%, vinyl content 0.47%, silanol content 1.02.

[0028] Example 3 Take a 2L three-necked flask, add 1000 grams of α, ω-hydroxy polydimethylsiloxane and 54 grams of α, ω-hydroxy polymethylvinylsiloxane (prepared in Example 1) into the reaction flask, heat to 70°C, and stir under vacuum for 30 minutes. Then break the vacuum, add 0.315 grams of linear chlorophosphazene toluene solution (2wt%), vacuum the reaction, and raise the temperature to 100°C. Stir for 10 minutes, the reaction will quickly become viscous, then add 18 grams of hexamethyldisiloxane, stir the reaction at normal pressure for 30 minutes, and then vacuum the reaction at 18mbar for 12 hours. After the reaction is completed, add 0.47 grams of triethylamine-toluene solution (2wt%) to terminate the reaction and stir at normal pressure for 60 minutes. A silicone oil intermediate is obtained with a volatile matter of 2.8% and a viscosity of 335mm 2 / s. The temperature was raised to 200℃ and vacuum was applied to remove low-volatile substances for 3 hours to obtain the final silicone oil product with a viscosity of 352.3mm 2 / s, volatile matter 0.34%, vinyl content 0.2%, silanol content 1.03.

[0029] Example 4 Take a 2L three-necked flask, add 1000 grams of α, ω-hydroxy polydimethylsiloxane and 250 grams of α, ω-hydroxy polymethylvinylsiloxane (prepared in Example 1) into the reaction flask, heat to 70°C, and stir under vacuum for 30 minutes. Then break the vacuum, add 0.375 grams of linear chlorophosphazene toluene solution (2wt%), vacuum the reaction, and raise the temperature to 100°C. Stir for 10 minutes, the reaction will quickly become viscous, then add 94 grams of hexamethyldisiloxane, stir the reaction at normal pressure for 30 minutes, and then vacuum the reaction at 25mbar for 10 hours. After the reaction is completed, add 0.57 grams of triethylamine-toluene solution (2wt%) to terminate the reaction and stir at normal pressure for 30 minutes. A silicone oil intermediate is obtained with a volatile matter of 8.7% and a viscosity of 36mm. 2 / s. The temperature was raised to 200℃ and vacuum was applied to remove low-volatile substances for 3 hours to obtain the final silicone oil product with a viscosity of 51.6mm. 2 / s, volatile matter 0.7%, vinyl content 0.74%, silanol content 1.02.

[0030] Example 5 Take 500g of 60,000mm 2 / s of vinyl-terminated silicone oil, adding 6wt% hexamethyldisilazane, 1.8wt% water, 2wt% hydrogenated silicone oil, 5wt% 100mm 2 / s methyl silicone oil containing side chain monovinyl (prepared in Examples 2-4 respectively), 0.5wt% vinyl silazane, mixed evenly in a planetary mixer, 30% white carbon black was added in batches, heated to 170℃ and stirred for 4 hours, vacuum reacted for 2 hours. Then the remaining 500g of 60,000mm 2 The vinyl-terminated silicone oil containing 1% PEG / s was uniformly diluted and allowed to react under vacuum for 2 hours to degas. The mixture was poured into a mold and cured at 160°C for 20 minutes, followed by vulcanization at 200°C for 4 hours to obtain liquid silicone rubber. Examples 2-4 were named Liquid Silicone Rubber 1, Liquid Silicone Rubber 2, and Liquid Silicone Rubber 3, respectively.

[0031] Comparative Example 1 Take a 2L three-necked flask, add 1000 grams of α, ω-hydroxy polydimethylsiloxane and 140 grams of α, ω-hydroxy polymethylvinylsiloxane (prepared in Example 1) into the reaction flask, heat to 70°C, and stir under vacuum for 30 minutes. Then break the vacuum, add 0.342 grams of linear chlorophosphazene toluene solution (2wt%), vacuum the reaction, and raise the temperature to 110°C. Stir for 10 minutes, the reaction will quickly become viscous, then add 48 grams of hexamethyldisiloxane, stir the reaction at normal pressure for 30 minutes, and then vacuum the reaction at 200mbar for 10 hours. After the reaction is completed, add 0.513 grams of triethylamine-toluene solution (2wt%) to terminate the reaction and stir at normal pressure for 30 minutes. Obtain a silicone oil intermediate with a volatile matter of 6.5% and a viscosity of 354mm 2 / s. The temperature was raised to 200℃ and vacuum was applied to remove low-volatile substances for 3 hours to obtain the final silicone oil product with a viscosity of 421mm 2 / s, volatile matter 0.48%, vinyl content 0.45%, silanol content 1.25, product indicators are unqualified.

[0032] Comparative Example 2 Take 500g of 60,000mm 2 / s of vinyl-terminated silicone oil, add 6wt% hexamethyldisilazane, 1.8wt% water, 2wt% hydrogenated silicone oil, 5wt% 100mm 2 / s methyl silicone oil, 0.5wt% vinyl silazane, mixed evenly in a planetary mixer, added 30% white carbon black in batches, heated to 170℃ and stirred for 4 hours, vacuum reacted for 2 hours. Then added the remaining 500g of 60,000mm 2 The vinyl-terminated silicone oil with a concentration of 100 μg / s was uniformly diluted and reacted under vacuum for 2 hours to degas. The mixture was poured into a mold and cured at 160°C for 20 minutes, followed by vulcanization at 200°C for 4 hours to obtain liquid silicone rubber 4.

[0033] Mechanical testing of all liquid silicone rubbers, including: According to GB / T529-2008, cut into rectangular samples, set 5 parallel samples for each sample, and test the tear strength; Dumbbell-shaped samples were cut according to GB / T528-2009, and 5 parallel samples were set for each sample to test the elongation at break and tensile strength.

[0034] Oil yield test: Cut the sample into 30 x 30 mm squares and weigh its initial mass, M1. Wrap the sample in filter paper, clamp it with glass slides, and place it in a 150°C constant-temperature drying oven for 72 hours. Remove the sample and weigh it, M2. Oil yield = (M1 - M2) / M1 * 100%.

[0035] The cured liquid silicone rubber was observed for oil exudation and the oil exudation rate was measured, and was left to stand for 3 months at room temperature, and observed for oil exudation and the oil exudation rate was measured.

[0036] The test results were as follows: .

Claims

1. A method for preparing methyl silicone oil containing a side chain monovinyl group, characterized in that: The following steps are involved: (1) Methylvinyldichlorosilane and dimethyldichlorosilicone oil are mixed evenly at 25-35°C, and then added dropwise to aqueous ammonia for hydrolysis reaction to obtain a mixture of crude vinyl hydroxy silicone oil and aqueous ammonium chloride solution; then, α,ω-hydroxy polymethylvinylsiloxane is obtained after oil-water separation, decolorization and decolorization. (2) Mixing α,ω-hydroxy polydimethylsiloxane and α,ω-hydroxy polymethylvinylsiloxane uniformly at 50-120°C, vacuum dehydration, adding linear phosphazene chloride catalyst solution, vacuum polycondensation reaction, adding hexamethyldisiloxane for equilibrium, adding terminator for neutralization reaction after the reaction, and obtaining silicone oil intermediate; (3) The intermediate is desulfurized at 180-200°C to obtain the finished silicone oil.

2. The method according to claim 1, characterized in that In step (1), the ratio of methylvinyldichlorosilane to dimethyldichlorosilicone oil is 1:5 wt%-25wt%, the concentration of ammonia water is 5-9wt%, the decolorization temperature is 50-100°C, and activated carbon is used for decolorization.

3. The method according to claim 2, characterized in that The obtained α,ω-hydroxy polymethylvinylsiloxane has a viscosity of 20-40mm 2 / s, vinyl content 2.5wt%-6wt%, structural formula is as follows: 。 4. The method according to claim 1, wherein The raw material α,ω-hydroxy polydimethylsiloxane in step (2) has a viscosity of 20-200mm 2 / s, volatile matter is less than 3%.

5. The method according to claim 1, wherein The raw materials in step (2) are α,ω-hydroxypolydimethylsiloxane, α,ω-hydroxypolymethylvinylsiloxane, and hexamethyldisiloxane in a ratio of 1:5wt%-25wt%:1.8wt%-10wt%.

6. The method according to claim 1, characterized in that In step (2), the catalyst is a linear phosphazene chloride solution with a concentration of 1wt%-5wt% and a solvent of 10-100mm 2 / s any one or more combinations of low-viscosity methyl silicone oil, toluene, ethyl acetate, and acetone; the terminator is an alkaline substance, including one or a combination of triethylamine, tripropylamine, diisopropylamine, hexamethyldisilazane, and butyl lithium, and the added amount is 1-3 times the mass of the catalyst.

7. The method according to claim 1, characterized in that In step (2), the polycondensation and equilibrium reactions are carried out under vacuum conditions, maintaining a vacuum degree of less than 50 mbar, and the reaction is carried out under normal pressure after the terminator is added; the polymerization reaction temperature is 50-120°C, and the polycondensation time is 8-12 hours; the temperature for adding the terminator is the polymerization temperature, and the termination time is 0.5-2 hours.

8. The method according to claim 1, characterized in that The intermediate in step (3) is deoxidized at a temperature of 180-200°C and for a time of 2-4 hours.

9. The methyl silicone oil containing a side chain monovinyl group prepared according to the method according to any one of claims 1 to 8, characterized in that: The methyl silicone oil product containing side chain monovinyl has a volatile content of less than 0.5%, a silanol content of 1.0±0.05, and a viscosity of 35-350mm 2 / s, vinyl content is 0.2%-0.5%.

10. A method for preparing liquid silicone rubber, characterized in that: Take vinyl-terminated silicone oil, hexamethyldisilazane, water, hydrogen-containing silicone oil, methyl silicone oil containing side chain monovinyl, and vinylsilazane, stir and mix well, then add white carbon black, heat to 160-170℃ and stir to react for 3-4 hours, vacuum react for 1-2 hours, then add vinyl-terminated silicone oil to dilute evenly, react under vacuum for 1-2 hours to degas, pour into a mold and solidify and vulcanize to obtain liquid silicone rubber.

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