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

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...

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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