阅读说明：本技术 一种用于合成聚氟硅氧烷的中和剂及其制备方法与应用 (Neutralizing agent for synthesizing polyfluorosiloxane and preparation method and application thereof ) 是由 田志钢 侯志伟 邵军强 夏金鹏 林峰 周建民 解乐福 于 2020-06-28 设计创作，主要内容包括：本发明涉及一种用于合成聚氟硅氧烷的中和剂及其制备方法与应用。所述制备方法,包括步骤：(1)向二烃基四甲基二硅氮烷中滴加乙酸,反应后过滤,滤液在保护气体下精馏得到烃基二甲基乙酰氧基硅烷；(2)将烃基二甲基乙酰氧基硅烷和三氟丙基甲基环三硅氧烷(D<Sub>3</Sub>F)混合均匀,继续加入催化剂进行反应,反应结束后加入乙酸钠,搅拌0.5～1h后过滤,滤液减压精馏得到用于合成聚氟硅氧烷的中和剂。本发明提供的用于合成聚氟硅氧烷的中和剂,相较于传统中和剂,纯度可高达99％以上,中和剂反应活性一致,中和剂用量可精确计算加入,并且相较于传统中和剂,中和更彻底,中和后聚氟硅氧烷的初始分解温度可达到480℃以上。(The invention relates to a neutralizing agent for synthesizing polyfluorosiloxane and a preparation method and application thereof. The preparation method comprises the following steps: (1) dropwise adding acetic acid into dialkyl tetramethyl disilazane, reacting, filtering, and rectifying filtrate under protective gas to obtain alkyl dimethyl acetoxy silane; (2) the hydrocarbyl dimethyl acetoxy silane and trifluoropropyl methyl cyclotrisiloxane (D) 3 F) And uniformly mixing, continuously adding a catalyst for reaction, adding sodium acetate after the reaction is finished, stirring for 0.5-1 h, filtering, and carrying out vacuum rectification on the filtrate to obtain a neutralizing agent for synthesizing the polyfluorosiloxane. Compared with the traditional neutralizing agent, the neutralizing agent for synthesizing the polyfluorosiloxane provided by the invention has the purity of over 99 percent, the reactivity of the neutralizing agent is consistent, the dosage of the neutralizing agent can be accurately calculated and added, and compared with the traditional neutralizing agentThe traditional neutralizing agent can neutralize more thoroughly, and the initial decomposition temperature of the neutralized polyfluorosiloxane can reach more than 480 ℃.)

1. A neutralizing agent for use in the synthesis of polyfluorosiloxanes having the structure:

2. the method of preparing a neutralizing agent for the synthesis of polyfluorosiloxane in accordance with claim 1, comprising the steps of:

(1) dropwise adding acetic acid into dialkyl tetramethyl disilazane, reacting for 1-2 h after dropwise adding, filtering, and rectifying filtrate under protective gas to obtain alkyl dimethyl acetoxy silane;

(2) the alkyl dimethyl acetoxy silicane prepared in the step (1) and trifluoropropyl methyl cyclotrisiloxane (D)₃F) And uniformly mixing, continuously adding a catalyst for reaction, adding sodium acetate after the reaction is finished, stirring for 0.5-1 h, filtering, and carrying out vacuum rectification on the filtrate to obtain a neutralizing agent for synthesizing the polyfluorosiloxane.

3. The method according to claim 2, wherein in the step (1), the dihydrocarbyl tetramethyldisilazane is divinyltetramethyldisilazane or hexamethyldisilazane.

4. The preparation method according to claim 2, wherein in the step (1), the molar ratio of the acetic acid to the dialkyl tetramethyl disilazane is (2-2.2): 1; the dropping time of the acetic acid is 1-3 h, and the dropping temperature is 40-50 ℃.

5. The preparation method according to claim 2, wherein in the step (1), the rectification conditions are as follows: at normal pressure, the temperature is 94-107 ℃, and the reflux ratio is 5: 1; the protective gas is nitrogen or argon.

6. The method according to claim 2, wherein in the step (2), the hydrocarbyl dimethyl acetoxy silane is reacted with D₃The molar ratio of F is (1.5-3): 1.

7. The preparation method according to claim 2, wherein in the step (2), the catalyst is a strong acid catalyst, and the mass ratio of the strong acid catalyst to the hydrocarbyl dimethyl acetoxy silane is (0.001-0.03): 1; further preferably trifluoromethanesulfonic acid, concentrated sulfuric acid or acid clay; most preferred is trifluoromethanesulfonic acid.

8. The method according to claim 2, wherein in the step (2), the hydrocarbyl dimethyl acetoxy silane and D are mixed₃The reaction temperature of F is 5-15 ℃, and the reaction time is 0.5-2 h.

9. The preparation method according to claim 2, wherein in the step (2), the mass ratio of the sodium acetate to the catalyst is (0.6-3): 1; the vacuum rectification conditions are as follows: the pressure is 266Pa, the temperature is 88-95 ℃, and the reflux ratio is 8: 1.

10. Use of the neutralizing agent for the synthesis of polyfluorosiloxane of claim 1 in the preparation of polymeric fluorosilicones;

furthermore, the neutralizing condition of the neutralizing agent for synthesizing the polyfluorosiloxane has no special requirement, and the neutralizing agent is added into a polymer system according to the acid-base molar ratio of 1:1 and stirred.

Technical Field

The invention relates to a neutralizing agent for synthesizing polyfluorosiloxane and a preparation method and application thereof, belonging to the field of organic silicon.

Background

The polymerization process of the organopolysiloxane is generally divided into anionic polymerization and cationic polymerization, wherein the cationic polymerization needs to use strong acid, the post-neutralization post-treatment process is complex, only a plurality of special organosilicon polymers are used in the process, the dosage of anionic polymerization catalysts is small, the complex post-treatment process is not needed, and the organopolysiloxane can be widely applied to the preparation of polysiloxane, in particular to the preparation of high molecular weight polysiloxane. The acidic substance is added to neutralize the alkaline catalyst after the polymerization reaction is finished in the preparation of polysiloxane by adopting anionic polymerization so as to avoid influencing the product quality or degrading the polysiloxane, and particularly, the acidic neutralizing agent which is sensitive to the alkaline substance has accurate actual adding amount and high reaction activity and plays an important role in the product quality. Polyfluorosiloxanes are more viscous and less compatible than polysiloxanes, and present greater difficulties in neutralization after completion of the anionic polymerization reaction.

In the prior art, after the anionic polymerization reaction of the organopolysiloxane is completed, carbon dioxide, acetic acid, phosphoric acid, silicon-based phosphate ester, phosphoric acid gum, vinyl silicon-based phosphate ester or vinyl acyloxy polysiloxane and the like are generally adopted as neutralizing agents, the neutralizing effects are different, and compared with common organopolysiloxane, the fluorosilicone polymer has the advantages of larger molecular rigidity, obviously improved viscosity, poorer compatibility with the neutralizing agent and poorer solubility for the neutralizing agent due to the introduction of fluorine atoms.

In the prior literature, for example, in Chinese patent literatureCN103910883A discloses a method for preparing fluorosilicone raw rubber with vinyl-containing end group, wherein the used neutralizer is one of α -chloroethanol, fluorine-containing organic silicon phosphonate, propionic acid or solid carbon dioxide, for example, in the method for preparing hydroxyl-terminated fluorosilicone raw rubber disclosed in Chinese patent document CN 104119535A, the used acidic compound is one of acetic acid, silicon-based phosphate, carbon dioxide, phosphoric acid, trimethylchlorosilane and hydrochloric acid, for example, in the method for preparing high molecular weight fluorosilicone raw rubber disclosed in Chinese patent document CN 103739845A, the used neutralizer is silicon-based phosphate generated by the reaction of hexamethyldisiloxane and phosphoric acid, for example, in the method for preparing fluorosilicone raw rubber with controllable molecular weight disclosed in Chinese patent document CN103012801, the used neutralizer is fluorine-containing silicon-based phosphate and is trifluoropropylmethyl cyclotrisiloxane (D)₃F) For example, in the method for preparing fluorosilicone crude rubber by using screw extruder disclosed in Chinese patent document CN102134321, the neutralizing agent used is one of carbon dioxide, chlorohydrin and organic silicon phosphate, among the above neutralizing agents, α -chlorohydrin, propionic acid, acetic acid, silicon-based phosphate, carbon dioxide, phosphoric acid, hydrochloric acid, trimethylchlorosilane, trimethylsilicon-based phosphate and the like have poor compatibility with polyfluorosiloxane₃The acid glue generated by the reaction of F has better compatibility with the high molecular weight polyfluorosiloxane, but the acid glue can cause hydroxyl end capping after neutralization, cause degradation at high temperature and easily cause the difficulty in mixing the high molecular weight fluorosilicone polymer. In addition, there is also a document that neutralization is carried out using a vinylacyloxy polysiloxane, but it is a mixture of materials of different molecular weights, the acetoxy activity is not completely the same, neutralization is liable to be nonuniform, and it is difficult to accurately measure the content of acetoxy therein which plays a role in neutralization.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a neutralizing agent for synthesizing polyfluorosiloxane and a preparation method and application thereof. The neutralizing agent has high purity, good compatibility with polyfluorosilicones with different molecular weights, high neutralizing efficiency, no hydroxyl generated after neutralization, and well solves the neutralizing problem of the polyfluorosilicone with high molecular weight.

The technical scheme of the invention is as follows:

a neutralizing agent for use in the synthesis of polyfluorosiloxanes having the structure:

according to the invention, the preparation method of the neutralizing agent for synthesizing the polyfluorosiloxane comprises the following steps:

(1) dropwise adding acetic acid into dialkyl tetramethyl disilazane, reacting for 1-2 h after dropwise adding, filtering, and rectifying filtrate under protective gas to obtain alkyl dimethyl acetoxy silane;

(2) the alkyl dimethyl acetoxy silicane prepared in the step (1) and trifluoropropyl methyl cyclotrisiloxane (D)₃F) And uniformly mixing, continuously adding a catalyst for reaction, adding sodium acetate after the reaction is finished, stirring for 0.5-1 h, filtering, and carrying out vacuum rectification on the filtrate to obtain a neutralizing agent for synthesizing the polyfluorosiloxane.

Preferably, in step (1), the dialkyl tetramethyldisilazane is divinyltetramethyldisilazane or hexamethyldisilazane.

According to the invention, in the step (1), the molar ratio of the acetic acid to the dialkyl tetramethyl disilazane is (2-2.2): 1. If the ratio of the two is less than 2:1, the silazane is not completely reacted, and if the ratio is more than 2.2:1, the content of acetic acid is too high, the separation is difficult, and the purity of the obtained alkyl dimethyl acetoxy silane is low.

According to the invention, in the step (1), the dripping time of the acetic acid is 1-3 h, and the dripping temperature is 40-50 ℃. If the dripping time of the acetic acid is less than 1h, the reaction temperature is increased too fast, a large number of byproducts are generated, and the dripping time is more than 3h, so that the reaction efficiency is influenced.

Preferably, in step (1), the rectification conditions are as follows: at normal pressure, the temperature is 94-107 ℃, and the reflux ratio is 5: 1; the protective gas is nitrogen or argon.

According to the invention, in step (2), the hydrocarbyl dimethyl acetoxy silane is preferably reacted with D₃The molar ratio of F is (1.5-3): 1. When hydrocarbyl dimethyl acetoxy silane is reacted with D₃The molar ratio of F is lower than 1.5:1, side reaction is easy to occur, a structural analogue of the compound I is generated, namely a mixture with 1-6 trifluoropropylsiloxy chain units, the compound I with higher purity cannot be obtained by rectification, when the alkyl dimethyl acetoxy silane and the D are reacted₃When the molar ratio of F is higher than 3:1, side reactions do not occur, but the rectification efficiency is affected by excessive hydrocarbyl dimethyl acetoxy silane.

According to the invention, in the step (2), the catalyst is a strong acid catalyst, and the mass ratio of the strong acid catalyst to the hydrocarbyl dimethyl acetoxy silane is (0.001-0.03): 1; further preferably trifluoromethanesulfonic acid, concentrated sulfuric acid or acid clay; most preferred is trifluoromethanesulfonic acid.

According to a preferred embodiment of the present invention, in step (2), said hydrocarbyl dimethyl acetoxy silane and D₃The reaction temperature of F is 5-15 ℃, and the reaction time is 0.5-2 h. If the reaction temperature is below 5 ℃, D₃F solidifies out to form a local D₃F is too much, silicon-oxygen chain rearrangement is easy to occur, the temperature is higher than 15 ℃, silicon-oxygen chain rearrangement reaction occurs, the number of trifluoropropylmethyl silicon-oxygen chain links cannot be controlled to be 3, but 1-6, and the high-purity compound I cannot be obtained. If the reaction time is less than 0.5h, D₃The F reaction is incomplete, the reaction time is more than 2h, and slow rearrangement reaction is easy to occur.

According to the invention, in the step (2), the mass ratio of the sodium acetate to the catalyst is (0.6-3): 1; the vacuum rectification conditions are as follows: the pressure is 266Pa, the temperature is 88-95 ℃, and the reflux ratio is 8: 1.

According to the invention, the use of a neutralizing agent for the synthesis of polyfluorosiloxane in the preparation of polymeric fluorosilicones; furthermore, the neutralizing condition of the neutralizing agent for synthesizing the polyfluorosiloxane has no special requirement, and the neutralizing agent is added into a polymer system according to the acid-base molar ratio of 1:1 and stirred.

The invention has not been described in detail, but is processed according to the conventional technology in the field.

The reaction equation of the invention is as follows:

the invention has the beneficial effects that:

1. compared with the traditional neutralizing agent, the neutralizing agent for synthesizing the polyfluorosiloxane has the advantages that the purity can reach more than 99 percent, the reactivity of the neutralizing agent is consistent, the using amount of the neutralizing agent can be accurately calculated and added, in addition, the neutralizing agent is more thorough compared with the traditional neutralizing agent, and the initial decomposition temperature of the polyfluorosiloxane after neutralization can reach more than 480 ℃.

2. The neutralizing agent for synthesizing the polyfluorosiloxane has good compatibility with the polyfluorosiloxane, generates no hydroxyl after neutralization, can be suitable for neutralizing polymeric fluorosilicones with different molecular weights, and is particularly suitable for neutralizing high-molecular-weight trimethyl-terminated or vinyl-terminated polyfluorosiloxane.

3. The preparation method disclosed by the invention is simple to operate, convenient and fast in process, low in production cost and easy to popularize and use to realize large-scale industrial production.

Drawings

FIG. 1 is a NMR spectrum of a neutralizer for synthesizing polyfluorosiloxane prepared in example 1.

Detailed Description

The present invention is further illustrated by, but is not limited to, the following specific examples.