A kind of neutralizing agent for synthesizing polyfluorosiloxane and its preparation method and application

Abstract

The invention relates to a neutralizing agent for synthesizing polyfluorosiloxane, a preparation method and application thereof. The preparation method comprises the steps of: (1) adding acetic acid dropwise to dihydrocarbyltetramethyldisilazane, filtering after reaction, and rectifying the filtrate under a protective gas to obtain hydrocarbyl dimethylacetoxysilane; (2) Hydrocarbyldimethylacetoxysilane and trifluoropropylmethylcyclotrisiloxane (D 3 F) Mix evenly, continue to add catalyst for reaction, add sodium acetate after the reaction, stir for 0.5 to 1 hour, filter, and rectify the filtrate under reduced pressure to obtain a neutralizing agent for synthesizing polyfluorosiloxane. Compared with the traditional neutralizing agent, the neutralizing agent used in the synthesis of polyfluorosiloxane provided by the invention has a purity of more than 99%, the neutralizing agent has the same reactivity, and the amount of the neutralizing agent can be accurately calculated and added. Compared with traditional neutralizers, the neutralization is more thorough, and the initial decomposition temperature of polyfluorosiloxane after neutralization can reach above 480°C.

Description

technical field [0001] The invention relates to a neutralizing agent for synthesizing polyfluorosiloxane, a preparation method and application thereof, and belongs to the field of organic silicon. Background technique [0002] The polymerization process of organopolysiloxane is generally divided into anionic polymerization and cationic polymerization. Among them, cationic polymerization requires the use of strong acid, and the post-neutralization and post-treatment process is complicated. Generally, only a few special organosilicon polymers use this process, and anionic polymerization catalysts are used. It is widely used in the preparation of polysiloxane, especially the preparation of high molecular weight polysiloxane. Anionic polymerization is used to prepare polysiloxane. After the polymerization reaction is completed, acidic substances are added to neutralize the basic catalyst, so as not to affect product quality or cause degradation of polysiloxane, especially fluoro...

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Problems solved by technology

Among the above neutralizing agents, α-chloroethanol, propionic acid, acetic acid, silicon-based phosphate, carbon dioxide, phosphoric acid, hydrochloric acid, trimethylchlorosilane, trimethylsilyl phosphate, etc. are compatible with polyfluorosiloxane poor sex

Although vinyl silyl phosphate has slightly better compatibility with polyfluorosiloxane, and has a better neutralization effect on polyfluorosiloxane oligomers, when the molecular weight of polyfluorosiloxane increases to gel, vinyl The neutralization effect of silicon-based phosphate ester will be significantly worse, and use vinyl silicon-based phosphate ester to neutralize, the vinyl group cannot be fully utilized, and the residual vinyl group will have an adverse effect on the vulcanization of high-temperature rubber. Phosphoric acid and D 3 The acid gel produced by the F reaction has good compatibility with high molecular weight polyfluorosiloxane, but after neutralization, it will cause hydroxyl end-blocking, which will cause degradation at high temperature and easily cause difficulty in mixing high molecular weight fluorosilicone polymers.

In addition, there are also literatures that use vinyl acyloxy polysiloxane for neutralization, but it is a mixture of materials with different molecular weights, and the activity of acetoxy groups is not completely the same, which is easy to cause uneven neutralization, and it is difficult to accurately measure it. Acetoxy content for neutralization

[0005] The existing technology cannot well solve the problems of rapid and accurate neutralization after the completion of the anionic polymerization reaction of high molecular weight polyfluorosiloxane and the absence of excess hydroxyl groups in the neutralized material.

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