阅读说明：本技术 聚二甲基硅氧烷的连续制备工艺 (Continuous preparation process of polydimethylsiloxane ) 是由 任海涛 刘彬 赵洁 曹鹤 李献起 张鹏硕 刘秋艳 严锦河 赵磊 胡质云 赵景辉 于 2019-09-30 设计创作，主要内容包括：本发明涉及二甲基硅氧烷的生产工艺,尤其是一种聚二甲基硅氧烷的连续制备工艺。将硅氧烷混合环体通过薄膜蒸发器一和干燥剂固定床脱除水分,通过活性炭固定床和离子交换树脂床去除金属离子；六甲基硅氧烷、硅氧烷混合环体按1:2～200的质量比经静态混合器混合后进入预热器预热到70～90℃；预热后物料进入列管式反应器中进行平衡化反应,列管内填充催化剂,反应温度70～90℃,反应停留时间0.5～2小时；通过过滤装置吸附残留的酸性物质和其他杂质；利用薄膜蒸发器二脱除低分子,真空度为0～-0.099Mpa,脱脂温度为150～250℃；脱除低分子后的成品经冷却降温后过滤包装。显著提高了生产效率,稳定了产品质量。(The invention relates to a dimethyl siloxane production process, in particular to a continuous preparation process of dimethyl polysiloxane. Removing water from the siloxane mixed ring body through a film evaporator I and a drying agent fixed bed, and removing metal ions through an active carbon fixed bed and an ion exchange resin bed; mixing hexamethyl siloxane and siloxane mixed ring bodies according to the mass ratio of 1: 2-200 by using a static mixer, and then preheating the mixture to 70-90 ℃ in a preheater; the preheated materials enter a tubular reactor for equilibrium reaction, catalysts are filled in the tubular reactor, the reaction temperature is 70-90 ℃, and the reaction residence time is 0.5-2 hours; adsorbing residual acidic substances and other impurities by a filtering device; removing low molecules by using a film evaporator II, wherein the vacuum degree is 0-minus 0.099Mpa, and the degreasing temperature is 150-250 ℃; and cooling the finished product after low molecular removal, filtering and packaging. Obviously improves the production efficiency and stabilizes the product quality.)

1. A continuous preparation process of polydimethylsiloxane is characterized by comprising the following steps:

A. Pretreatment of raw materials: removing water from the siloxane mixed ring body through a film evaporator I and a drying agent fixed bed, and removing metal ions through an active carbon fixed bed and an ion exchange resin bed, wherein the operating temperature of the film evaporator I is 60-80 ℃, and the vacuum degree is-0.06-0.08 Mpa;

B. preheating: mixing hexamethyl siloxane and siloxane mixed ring bodies according to the mass ratio of 1: 2-200 by using a static mixer, and then preheating the mixture to 70-90 ℃ in a preheater;

C. Telomerization: the preheated materials enter a tubular reactor for equilibrium reaction, catalysts are filled in the tubular reactor, the reaction temperature is 70-90 ℃, and the reaction residence time is 0.5-2 hours;

D. purifying: adsorbing residual acidic substances and other impurities by a filtering device;

E. Removing low molecules: removing low molecules by using a film evaporator II, wherein the vacuum degree is 0-minus 0.099Mpa, and the degreasing temperature is 150-250 ℃;

F. Cooling and packaging: and cooling the finished product after removing the low molecules, and then filtering and packaging.

2. The continuous process for the preparation of polydimethylsiloxanes according to claim 1, characterized in that: and B, adopting coconut shell activated carbon as activated carbon in the activated carbon fixed bed in the step A.

3. The continuous process for the preparation of polydimethylsiloxanes according to claim 1, characterized in that: and the desiccant fixed bed in the step A adopts spherical calcium chloride particles as a desiccant.

4. the continuous process for the preparation of polydimethylsiloxanes according to claim 1, characterized in that: and D, the heat required by the preheater in the step B is used as the waste heat of the finished product.

5. The continuous process for the preparation of polydimethylsiloxanes according to claim 1, characterized in that: and D, filling the catalyst filled in the tubes in the step C into acid clay or cation acid resin catalyst.

6. the continuous process for the preparation of polydimethylsiloxanes according to claim 1, characterized in that: and D, filling activated clay into the filtering device in the step D.

7. the continuous process for the preparation of polydimethylsiloxanes according to claim 1, characterized in that: and C, the tubular reactor in the step C is made of titanium.

Technical Field

the invention relates to a dimethyl siloxane production process, in particular to a continuous preparation process of dimethyl polysiloxane.

Background

In the production process of polydimethylsiloxane, dimethyl cyclosiloxane (D4 or DMC) with low molar mass and hexamethyldisiloxane are generally adopted industrially to be prepared by a kettle type batch reaction.

Disclosure of Invention

in order to solve the technical problems, the invention provides a continuous preparation process of polydimethylsiloxane with high efficiency and good product quality.

The invention adopts the following technical scheme:

A continuous preparation process of polydimethylsiloxane comprises the following steps:

A. Pretreatment of raw materials: removing water from the siloxane mixed ring body through a film evaporator I and a drying agent fixed bed, and removing metal ions through an active carbon fixed bed and an ion exchange resin bed, wherein the operating temperature of the film evaporator I is 60-80 ℃, and the vacuum degree is-0.06-0.08 Mpa;

B. preheating: mixing hexamethyl siloxane and siloxane mixed ring bodies according to the mass ratio of 1: 2-200 by using a static mixer, and then preheating the mixture to 70-90 ℃ in a preheater;

C. Telomerization: the preheated materials enter a tubular reactor for equilibrium reaction, catalysts are filled in the tubular reactor, the reaction temperature is 70-90 ℃, and the reaction residence time is 0.5-2 hours;

D. Purifying: adsorbing residual acidic substances and other impurities by a filtering device;

E. Removing low molecules: removing low molecules by using a film evaporator II, wherein the vacuum degree is 0-minus 0.099Mpa, and the degreasing temperature is 150-250 ℃;

F. Cooling and packaging: and cooling the finished product after removing the low molecules, and then filtering and packaging.

Compared with the prior art, the invention has the beneficial effects that:

The preparation process can realize continuous preparation, the production efficiency is high, and the prepared product has stable quality; the raw materials can ensure the service time of the resin catalyst after purification treatment, and the production cost is reduced; the crude product can remove residual acidic substances and other impurities through purification treatment, so that the quality of the product is further improved; the waste heat of the product provides heat for preheating, and the waste heat is circulated, so that more energy is saved.

Further, the invention adopts the following preferable scheme:

And B, adopting coconut shell activated carbon as activated carbon in the activated carbon fixed bed in the step A.

And the desiccant fixed bed in the step A adopts spherical calcium chloride particles as a desiccant.

And D, the heat required by the preheater in the step B is used as the waste heat of the finished product.

And D, filling the catalyst filled in the tubes in the step C into acid clay or cation acid resin catalyst.

And D, filling activated clay into the filtering device in the step D.

And C, the tubular reactor in the step C is made of titanium.

drawings

FIG. 1 is a schematic flow diagram of the present invention;

In the figure: a first thin film evaporator 1; a desiccant fixed bed 2; an activated carbon fixed bed 3; an ion exchange resin bed 4; a preheater 5; a tubular reactor 6; a filtering device 7; and a second thin film evaporator 8.

Detailed Description

The invention is further described below with reference to the accompanying drawings and specific embodiments.