Method for synthesizing low-viscosity room temperature vulcanized methyl silicone rubber

A technology of methyl silicone rubber and room temperature vulcanization, which is applied in the field of organic chemistry, can solve the problems of low 107 rubber, affect transparency and quality, and cannot prepare viscosity, etc., achieve the effect of large viscosity deviation and save production cost

Active Publication Date: 2018-11-30
HUBEI XINGRUI SILICON MATERIAL CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These patents and papers respectively introduce the low-viscosity 107 glue synthesis process, but there are the following problems in the actual production process: (1) Carbonate is used as the basic catalyst, because the amount of low-carbonate with catalytic activity is large, when the product is filtered It cannot be filtered thoroughly, and part of the salt is dissolved in the product, which affects the transparency and quality; (2) DMC is used for high-temperature catalysis, and then degraded by adding water. Due to factors such as reaction activation energy and equilibrium reaction, it is impossible to prepare 107 glue with low viscosity; (3) Using hydrolyzate or linear body under the condition of strong acid resin catalyst, low viscosity 107 glue can be prepared. In the actual production process, the cost of resin catalyst is high and it needs to be treated as hazardous waste after deactivation

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] A multi-stage filtration system is used to filter 5500kg of hydrolyzate, and the line body of the hydrolyzate is HO[Si(CH 3 ) 2 O] n The H content is 80%, the acid value is 0.005mgKOH / g, the viscosity is 20-150mPa.s, the turbidity is 0.5-5.0NTU, the calcium content is 0-2ppm, the iron content is 0-2ppm, and the aluminum content is 0-0.2 ppm, the filtered material is poured into the polymerization kettle, the stirring is started and the material is heated up, and the stirring frequency is 30Hz. When the material temperature is 120°C, add a 20% potassium hydroxide aqueous solution with a mass fraction of 5.5 g of potassium hydroxide. After 30 minutes, nitrogen gas is blown to the bottom of the polymerization tank at a rate of 3 m3 / h. When the viscosity of the material increases to 70 mPa.s Stop nitrogen sparging. Continue the reaction, the viscosity of the material increases to 105mPa.s, add a phosphoric acid solution with a mass concentration of 75% for neutralization...

Embodiment 2

[0020] A multi-stage filtration system is used to filter 5500kg of hydrolyzate, and the line body of the hydrolyzate is HO[Si(CH 3 ) 2 O] n The H content is 90%, the acid value is 0.015mgKOH / g, the viscosity is 20-150mPa.s, the turbidity is 0.5-5.0NTU, the calcium content is 0-2ppm, the iron content is 0-2ppm, and the aluminum content is 0-0.2 ppm, the filtered material is poured into the polymerization kettle, the stirring is started and the temperature of the material is raised, and the stirring frequency is 40Hz. When the material temperature is 80°C, add a 5% potassium hydroxide aqueous solution with a mass fraction of 20g of potassium hydroxide. After 40 minutes, nitrogen gas is blown to the bottom of the polymerization kettle. The nitrogen gas rate is 2.5m3 / h, and when the viscosity of the material increases to 40mPa.s Stop nitrogen sparging. Continue the reaction, the viscosity of the material increases to 75mPa.s, and add silicon-based phosphoric acid for neutraliza...

Embodiment 3

[0022] A multi-stage filtration system is used to filter 5500kg of hydrolyzate, and the line body of the hydrolyzate is HO[Si(CH 3 ) 2 O] n The H content is 75%, the acid value is 0.10mgKOH / g, the viscosity is 20-150mPa.s, the turbidity is 0.5-5.0NTU, the calcium content is 0-2ppm, the iron content is 0-2ppm, and the aluminum content is 0-0.2 ppm, the filtered material is poured into the polymerization kettle, the stirring is started and the temperature of the material is raised, and the stirring frequency is 40Hz. When the material temperature was 108.8°C, potassium hydroxide silicon alkoxide was added (the content of potassium hydroxide was 50g, and the mass of dimethylsiloxane mixed ring DMC was 1500g). After 30 minutes, nitrogen gas was blown to the bottom of the polymerization kettle, and the nitrogen gas rate was 1.5 m3 / h, stop blowing nitrogen when the viscosity of the material increases to 20mPa.s. Continue the reaction, the viscosity of the material increases to 65...

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PUM

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Abstract

The invention relates to a method for synthesizing low-viscosity room temperature vulcanized methyl silicone rubber. According to the method, a dimethyl dichlorosilane concentrated-acid hydrolyzate istaken as a raw material to undergo a polycondensation reaction under action of a basic catalyst, the viscosity of the reaction material is monitored by a low-range online viscometer, a neutralizing agent is added after a target viscosity is reached, the reaction product is subjected to low-molecule removal treatment at a high temperature under vacuum, so that a low-viscosity room temperature vulcanized methyl silicone rubber product is obtained. According to the invention, on the basis of conventional viscosity room temperature vulcanized methyl silicone rubber production technologies, the method further makes the viscosity change of the reaction system one-way smooth by reducing the catalyst usage amount, lowering the reaction temperature condition, shortening the reaction equilibrium time, widening raw material loop ratio requirements and employing other technological means. The inorganic salt content of the catalytic system is reduced by 70% or more on year-on-year basis, the production efficiency is increased by 50% or more, the primary viscosity qualification rate reaches 95%, the product turbidity is 1.0 NTU or below, the Mw / Mn ratio is small and the hydroxyl value is high,and meanwhile, the dehydration process is optimized and product quality is stable.

Description

technical field [0001] The invention relates to a synthesis process of room temperature vulcanized silicone rubber, which belongs to the field of organic chemistry. Background technique [0002] In the silicone series products, hydroxyl-terminated dimethyl siloxane is a special rubber that can be vulcanized at room temperature. It has a wide range of operating temperatures, radiation resistance, high and low temperature resistance, and excellent heat dissipation. Adhesive, fluidity and mold release properties. Silicone rubber can maintain a certain degree of softness, resilience, aging resistance and interface hardness within the temperature range of use. It is widely used in construction, coatings, arts and crafts and other fields. [0003] It has been disclosed that the low-viscosity 107 glue has the following preparation methods: Patent CN 105254893A "A Low-viscosity 107 glue and its preparation method" introduces the use of DMC under negative pressure polymerization at 1...

Claims

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Application Information

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IPC IPC(8): C08G77/06C08G77/08
CPCC08G77/06C08G77/08
Inventor 孙刚肖靖袁盛泽胡东华蒋安军陈泽雨张光荣马强
Owner HUBEI XINGRUI SILICON MATERIAL CO LTD
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