WO2024051671A1

WO2024051671A1 - Polymerization-termination device and method for continuous production of organopolysiloxanes

Info

Publication number: WO2024051671A1
Application number: PCT/CN2023/116914
Authority: WO
Inventors: 高东静; 李鹏翀; 邹灯旺; 戈录才; 吴超波
Original assignee: 江西蓝星星火有机硅有限公司
Priority date: 2022-09-06
Filing date: 2023-09-05
Publication date: 2024-03-14
Also published as: CN115417991A; CN115417991B

Abstract

The present invention relates to a polymerization-termination device and method for the continuous production of organopolysiloxanes. The device of the present invention comprises a reactor 1 and a reactor 2, which are directly connected to each other, wherein the polymerization reaction of a siloxane and devolatilization are performed in the reactor 1, and the termination of the polymerization reaction and deep devolatilization are performed in the reactor 2. The device of the present invention has a simple structure, improves the efficiency of polymerization and termination, and realizes controllable polymerization. The produced organopolysiloxane has a good quality, including a preparable product having a wide viscosity range, a small quantity of volatile components, a low content of impurities, a high transparency, a high thermal stability, etc.

Description

Polymerization-termination device and method for continuous production of organopolysiloxane

Technical field

The present invention relates to the technical field of organopolysiloxane production.

Background technique

Linear organopolysiloxane is a type of silicone polymer with -Si-O-Si- bonds as the main chain. It is the basic polymer material in the silicone industry. A large number of downstream silicone formula products with different functions can be obtained by adding various additives, fillers, etc. to the linear organopolysiloxane. The industrial production of linear organopolysiloxane is usually obtained by heating the raw material octamethylcyclotetrasiloxane (D4) or dimethylsiloxane ring (DMC) to the polymerization temperature (> 80℃), under the catalysis of strong acid or strong alkali, it goes through the process of polymerization chain growth-chain transfer-chain termination, and is kept at this temperature for a period of time. After the polymer is adjusted to the required viscosity, a terminator is added to terminate the reaction. The above process is a catalytic equilibrium process, and there is about 10-16% cyclosiloxane in the final product. It is necessary to remove small molecules and low boilers through a high temperature and pressure reduction process to obtain the target product. Various Bronsted acids and bases and Lewis acids and bases can be used as catalysts in the siloxane polymerization process.

According to different types of polymerization, polymerization reactions can be divided into ring-opening polymerization and condensation polymerization. For example, Chinese patent CN102093651B proposes to prepare catalysts A and B by reacting potassium hydroxide or tetramethylammonium hydroxide with dimethylsiloxane rings respectively. A and B are mixed and refined in a certain proportion to obtain a composite catalyst. Efficient catalysis to prepare 107 glue from high ring body. CN107216456A discloses that a mixture of polydimethylsiloxane rings and linear bodies is used as raw material, and a silicone-hydroxyl-containing polymer is used as the end-capping agent. Under the catalysis of a caged phosphazene superbase, a silicone-hydroxyl-terminated polydiethylene is obtained. Methyl siloxane, and finally add an acidic substance to terminate the reaction.

The process flow of siloxane polymerization can be roughly divided into three categories: batch method, semi-continuous method and continuous method, each using different forms of reaction devices.

The batch method, that is, the polymerization reactor batch process is the most commonly used method. Before the polymerization begins, various materials, including cyclic siloxane or linear siloxane, end-capping agents and catalysts, need to be mixed evenly in the reactor. , and heated from normal temperature to reaction temperature (80-180°C). Limited by the stirring efficiency of the paddle reactor, it takes a long time for mass transfer and heat transfer to be uniform. In the later stage of the reaction, due to the certain viscosity of the product, the mass transfer and heat transfer process becomes more difficult. In order to fully react with all materials and achieve In the polymerization equilibrium state, it is necessary to extend the residence time of the material in the reactor, so the polymerization The combined reaction time is usually more than 3-4h.

For the polymerization process of siloxane, the batch method has the disadvantage of low reaction efficiency. In the presence of commonly used alkaline catalysts such as potassium hydroxide, it is necessary to add a terminator to the reactor in time after the polymerization is completed to terminate the catalytic process and at the same time neutralize the pH of the product. Also due to low stirring efficiency, it takes a long time to achieve full dispersion after the terminator is added, which will increase the process time. Even so, for high-viscosity silicone products, it is still impossible to achieve a sufficient dispersion effect, that is, the uniformity and immediacy of the reaction system cannot be guaranteed, which makes the molecular weight, viscosity, volatile matter and other indicators of the polymerized product uncontrolled and deviating from the specification requirements. scope. Therefore, in order to achieve better termination (neutralization) effect, the terminator is generally required to be in a large excess over the catalyst. However, more inorganic salts will be produced when the reaction is terminated and remain in the system, resulting in a decrease in product purity, stability and transparency.

The batch method also has the disadvantage of poor devolatilization effect. The polymerization reaction is generally an equilibrium reaction. After the reaction is completed, there are a large number of low-boiling substances in the product that need to be removed. Since the products in the reactor accumulate from bottom to top and are thick, there is no effective film-forming mechanism to increase the gas-liquid mass transfer area. Especially when the viscosity of the organic silicon product is large, the devolatilization process becomes more difficult. In addition, the temperature difference formed in the upper space of the reaction kettle can easily cause the vaporized low-boiling substances to re-condensate and reflux. Even if inert gases such as nitrogen are blown from the bottom to bring out the vaporized substances, the effect will be caused by insufficient bubble dispersion and easy aggregation. Limited, but it will lead to environmental pollution due to difficulty in exhaust gas recovery. In addition, the low-boiling substances in the ring have a high boiling point, and the devolatilization process requires heating and pressure reduction. The heating temperature is usually above 200°C. High temperatures for a long time can easily cause local overheating, and may cause product deterioration, cross-linking, etc. in the stirring dead zone. contaminate the final product. In order to keep the volatile content of silicone products at around 1%, more power is required and a devolatilization time of up to 4-10 hours is required. It can be seen that the batch method has the disadvantages of low reaction efficiency and poor devolatilization effect. In addition to the above defects, there will inevitably be quality differences in products produced in different batches using the intermittent method, making it difficult to accurately control quality.

Semi-continuous equipment usually uses multiple larger polymerization reactors connected in series, which can separate the polymerization process, termination reaction and devolatilization process, thereby saving time and improving production capacity. However, larger production space and more complex operating procedures are inevitably required. When the product viscosity is high, material transfer between different reactors becomes extremely difficult and energy-consuming. Other drawbacks of the batch process, such as broad product molecular weight distribution due to uneven stirring, still exist in semi-continuous processes.

The continuous method generally uses a tubular reactor with strong convection characteristics as the polymerization equipment, but it can only produce products with a maximum molecular weight of about 600,000-800,000. If higher molecular weight silicone products are produced, it is difficult to overcome the problem of raw materials and products. The huge viscosity difference between the two causes back-mixing, which means that the plug flow cannot be maintained, and the molecular weight uniformity becomes very Difference. High-viscosity products need to maintain a certain flow rate in the tubular reactor, which requires a huge pressure drop to maintain, which increases power loss. In addition, after the reaction is completed, additional reactors are still needed to terminate the reaction and complete the low-volatilization process. There are many ancillary equipment and high investment.

In summary, although with the development of the silicone industry, the synthesis scale of linear or cyclic organopolysiloxanes has gradually increased, various defects in traditional processes and devices still restrict the realization of low energy consumption and low emissions. , low pollution and high efficiency production are the main reasons. Moreover, it is difficult for organopolysiloxanes prepared with the existing technology to have excellent quality. Generally, the product viscosity range is narrow, the viscosity is difficult to accurately control, the molecular weight distribution is uneven, the volatile content is high, and the thermal stability and long-term storage stability are Various shortcomings such as poor stability, high content of inorganic salt impurities, and poor transparency have greatly affected the performance and stability of downstream formulated product applications.

Although some methods for producing organopolysiloxane have been proposed in the prior art, they all have various deficiencies that are difficult to solve.

US4551515A discloses a process for the continuous production of organic silicone rubber. First, mix the siloxane ring with the chain end-capping agent, preheat it to above 130°C, and then add potassium silanolate as a catalyst. The above mixture first enters the first The preliminary polymerization reaction is carried out in a static pre-reactor, and the obtained preliminary polymerization product continues to enter the second static pre-reactor for polymerization. At this time, the viscosity of the discharged material is about 2,000,000cP, and then enters the single-screw Buss- with multiple kneading units. The Condux device performs deep polymerization and removes low-boiling substances, and at the same time injects silyl phosphate into the rear end of the single screw to terminate the reaction. Finally, a raw rubber product with a uniform molecular weight distribution can be obtained, and the subsequent application performance is consistent with the polymer produced by the batch method. .

However, this process can only produce silicone polymers with a viscosity above 500,000 cP. This may be because the single-screw structure is prone to leakage and cannot carry low-viscosity materials. Moreover, before the reaction materials enter the screw reactor, they need to be premixed and preheated, and then polymerized through two series-connected static mixers to reach a certain viscosity. The single-screw structure increases the complexity of the equipment. In addition, the single-screw kneading effect is poor, and the surface renewal rate of the material in the exhaust zone is small. Therefore, the gas-liquid mass transfer effect is poor, and the volatile matter of the resulting products is high.

US6221993B1 discloses a process for continuously producing silicone polymers, which can use linear siloxane containing terminal silanol groups as raw materials (condensation polymerization), or cyclosiloxane as raw materials (ring-opening polymerization), or the above-mentioned The mixture of the two substances is used as raw material and is polymerized in the reaction zone of a twin-screw extruder in the presence of a catalyst phosphazene base and a small amount of water as a promoter. The initial polymerization product obtained has a higher yield; the initial polymerization product is continued Transported to the neutralization zone of the twin-screw extruder and thoroughly mixed with the terminator silylphosphonate to terminate the polymerization reaction; leave the neutralization zone The materials continue to travel to the stripping zone of the Z-slurry kneader or twin-screw extruder, where the low boiling matter is removed by raising the temperature and reducing the pressure. The final product has less than 1% volatile matter and extremely high stability, with a decomposition temperature as high as 567°C.

The above-mentioned process carries out polymerization, termination and devolatilization processes in different sections of an extruder respectively, resulting in each functional section being relatively cramped. Moreover, the length-to-diameter ratio of the screw is limited, and the complete completion of each stage of the process cannot be guaranteed. The concentration of different functional sections on one extruder also increases the risk of malfunctions and misoperation during continuous production. In addition, in the examples, only silicone polymers with a molecular weight of more than 90,000 were prepared, and the applicable product range Single, not suitable for producing lower viscosity organopolysiloxane products.

CN111574714B discloses a production method of polysiloxane, in which the polymerization reaction is completed by a polymerization twin-screw extruder, the termination reaction is completed by a static mixer, and the devolatilization process is performed by a falling strip devolatilizer and another Devolatilization twin-screw extruder is completed together. The overall design of the equipment is bloated, which greatly increases the risk of failure during continuous production. Moreover, it is difficult to achieve real-time control of product viscosity with static mixers. When the static mixer handles the termination reaction of high-viscosity materials, because the flow values of the high-viscosity materials and the terminator are very different, and the viscosities of the two types of fluids are also very different, within the static mixing residence time of usually ten seconds to several minutes, It is difficult to mix the two types of materials evenly, and the neutralization efficiency is low, that is, the internal reaction of the high-viscosity material cannot be completely terminated during this process; and the high-viscosity material contains a certain amount of low-boiling by-products, which makes the viscosity difference with the final product smaller. Large, so it is impossible to achieve instant control of product viscosity/molecular weight. Although this patent mentions that lower viscosity polysiloxane can be prepared, due to the use of a drop-type devolatilizer, it is not suitable for the preparation of low-viscosity products in industrial practice. In addition, due to the use of static mixers and drop-type devolatilizers, they are not suitable for seamless switching of production lines and cannot prepare various types of organopolysiloxanes. In addition, the polymerization, termination and devolatilization processes are carried out in different equipment, which increases the time consumption of the overall process.

CN205115352U discloses a device that can be used for devolatilization of ultra-high molecular weight polysiloxane. A porous plate, front and back cones containing holes, etc. are provided in the tank, which are respectively arranged in different spatial positions. The ultra-high molecular weight polysiloxane can be devolatilized. The siloxane is divided into ribbon-shaped colloids and flows down, increasing the specific surface area and extending its residence time in the device, strengthening the mixing process and helping to quickly remove volatile matter. After treating ultra-high molecular weight polysiloxane for 2-3 hours, a product with a volatile content of less than 0.8% can be obtained, and its uniformity is improved.

Although this patent can achieve a lower volatile content, the devolatilization process still takes more than a few hours. This is because the principle of the polymer devolatilization process is to increase the surface area of high-viscosity materials to create a gas-liquid phase interface for mass transfer, and update the interface during multiple mixing processes to increase the driving force of gas-liquid mass transfer. However, due to the large volume of the formed ribbon colloid, the specific surface area is still small, and the surface renewal rate caused by passive mixing is slow, which makes the devolatilization treatment time longer.

CN102140170B discloses a new process for synthesizing permethyl silicone oil with a molecular weight of 55,000-70,000. After the reaction is terminated, the material is dispersed into filaments through the flower plate and then flashed in the devaporizer to remove low-molecular impurities, which can complete the devolatilization process quickly. However, this document does not mention the value of volatile matter in the final product.

CN103435808A proposes dehydrating the siloxane ring, heating it to a predetermined temperature through a preheater, feeding it into an online mixer together with the catalyst, stirring evenly, and entering the polymerization cylinder to continue heating to the reaction temperature. After 1-1.5 hours of reaction, Then it enters the degrader to react with water vapor for degradation, and finally enters the twin-screw glue discharging machine to remove water vapor and low-boiling products and decompose the catalyst to continuously produce 107 glue. The disadvantage of this document is that the volatile content is still high, and the twin-screw glue machine only plays a devolatilization role in the process. The early polymerization process is still similar to the traditional process and takes a long time.

CN205241587U proposes to carry out the polymerization reaction in the reactor, then enter the material into a static mixer for de-lowering, then enter the counter-rotating conical twin-screw extruder, and discharge the material into a parallel vacuum twin-screw extruder for secondary de-lowering. The volatile content of the prepared organopolysiloxane with a molecular weight of 1 million to 2 million is less than 0.6%. The disadvantage is that in order to achieve lower volatile matter, multiple sets of equipment are used in series, which results in redundant functions and takes a long time.

The above existing technologies respectively explore the polymerization reaction, termination reaction and devolatilization process in the industrial production of organopolysiloxane, but there are various unresolved problems. Although patent US6221993B1 concentrates polymerization, termination and devolatilization on one device, it can only prepare products with a molecular weight of more than 90,000, and the volatile fraction of the final product is about 1%, which is still difficult to meet the needs of various downstream formulation applications. Silicone polymer requirements.

There is still an urgent need for a method that can efficiently and continuously produce organopolysiloxane, which can solve the various shortcomings and defects in the existing technology mentioned above.

The object of the present invention is to provide a polymerization-termination device for the continuous production of organopolysiloxane and a method thereof. This method achieves many improvements.

1. Overcoming the shortcomings of traditional process equipment such as complex and complicated structure, low spatiotemporal efficiency, high energy consumption and low productivity, the present invention has a simplified structure and good process repeatability.

2. Improve the efficiency of polymerization reaction and termination reaction. The device of the present invention has strong distribution and mixing ability, easy mass and heat transfer, easy feeding and discharging, and high production efficiency.

3. The device of the present invention can achieve effective control of the termination reaction, thereby obtaining the desired product viscosity range and achieving precise control of the product molecular weight/viscosity.

4. Organopolysiloxane products with a wide viscosity range can be prepared, including various types of low-viscosity silicone oil, high-viscosity silicone oil and silicone rubber raw rubber, etc. to meet the needs of downstream production. The organopolysiloxanes produced have a viscosity range from 300 mPa·s to 20,000,000 mPa·s (cP).

5. Improve the quality of organopolysiloxane products. The products have low volatile content, uniform molecular weight distribution, low inorganic salt content, good transparency, and high thermal stability. More importantly, a narrow molecular weight distribution can be maintained over a very wide product viscosity range.

6. Short devolatilization time.

Contents of the invention

The present invention relates to a polymerization-termination device for the continuous production of organopolysiloxane, comprising:

Reactor 1, which is used for polymerization of siloxane;

The feed port of reactor 2 is connected with the discharge port of reactor 1 and is used to terminate the polymerization reaction.

In a preferred embodiment, reactor 1 removes volatile matter while carrying out polymerization reaction, and/or reactor 2 removes volatile matter while carrying out termination of polymerization reaction.

In a preferred embodiment, the viscosity range of the produced organopolysiloxane is 300-20,000,000mPa·S, preferably 1,000-10,000mPa·S, more preferably 100,000-1,000,000mPa·S, even more preferably 3,000,000- 10,000,000mPa·S. More specifically, the organopolysiloxanes produced have a viscosity range selected from the group consisting of 300, 1000, 2000, 3000, 5000, 10,000, 20,000, 50,000, 80,000, 100,000, 300,000, 500,000, 1,000,000, 3,000,000, 5,000,000 , 10,000,000, 15,000,000 , 20,000,000mPa·S or any sub-interval between them.

In a preferred embodiment, the organopolysiloxane produced has a volatile content of less than 0.5%, preferably less than 0.3%.

In a preferred embodiment, the produced organopolysiloxane has a narrow molecular weight distribution, preferably 1.4-2.3, more preferably 1.5-2.0.

In a preferred embodiment, the organopolysiloxane produced has a low inorganic salt content, preferably <11 ppm, more preferably <0.1 ppm.

In a preferred embodiment, the organopolysiloxane produced has a high thermal stability, preferably a thermal decomposition temperature The thermal decomposition temperature is 380°C-510°C, and the more preferred thermal decomposition temperature is 385°C-470°C.

In a preferred embodiment, the reactor 1 is a co-rotating or counter-rotating twin-screw extruder 1, and the reactor 2 is a co-rotating or counter-rotating twin-screw extruder 2.

In a preferred embodiment, the front end of the reactor 2 is provided with a terminator feeding port.

In a preferred embodiment, the outlet of the reactor 1 is directly connected to the inlet of the reactor 2, preferably in a straight line or vertically to each other or at other angles.

In a preferred embodiment, the screw diameter of the twin-screw extruder 1 is 36-360mm, preferably 120-240mm.

In a preferred embodiment, the screw diameter of the twin-screw extruder 2 is 36-240mm, preferably 80-240mm.

In a preferred embodiment, the screw speed of the twin-screw extruder 1 is 1-200 rpm, preferably 1-150 rpm, more preferably 50-120 rpm.

In a preferred embodiment, the screw speed of the twin-screw extruder 2 is 1-600 rpm, preferably 1-150 rpm, more preferably 60-150 rpm.

In a preferred embodiment, the temperature of the reactor 1 is 20-180°C, preferably 110-150°C, more preferably 80-110°C.

In a preferred embodiment, the temperature of the reactor 2 is 20-180°C, preferably 100-170°C, more preferably 160-170°C.

In a preferred embodiment, the pressure of the reactor 2 is 0-50kPa, preferably 0-5kPa.

In a preferred embodiment, the raw material used to produce the organopolysiloxane may be a linear siloxane, a cyclic siloxane or a mixture of the two.

In a preferred embodiment, for the linear siloxane raw material, the temperature of reactor 1 is 80-110°C, the rotation speed of reactor 1 is 50-120rpm, and the temperature of reactor 2 is 160-170°C. The rotation speed of 2 is 60-150 rpm, so that organopolysiloxanes with a wide molecular weight/viscosity range can be prepared, such as organopolysiloxanes with a viscosity of 20,000mPa·S-20,000,000mPa·S. More importantly, the ability to maintain a narrow molecular weight distribution, such as 1.5-1.8, over a very wide molecular weight/viscosity range.

The present invention also relates to a polymerization-termination method for continuously producing organopolysiloxane using the device of the present invention, which includes the following steps:

a) Sequentially add siloxane, end-capping agent and catalyst including linear siloxane or cyclic siloxane or a mixture of the two into reactor 1 to perform polymerization reaction while performing partial devolatilization to obtain the unpolymerized product. terminated initial product;

b) Extrude the unterminated initial product of the polymerization reaction from the reactor 1 and transport it to the reactor 2, where it is fully mixed with the terminator to terminate the polymerization reaction and perform deep devolatilization at the same time to obtain organic Polysiloxane products.

In a preferred embodiment, the linear siloxane or cyclic siloxane in step a) has the following repeating structural unit - [SiR ¹ R ² -O-] _n , where n is 1 to 500 , preferably 2-100, more preferably 3-20, R ¹ and R ² are H or optionally substituted alkyl, alkenyl, aryl, alkaryl or aralkyl, etc.

In a preferred embodiment, the end-capping agent is selected from divinyltetramethyldisiloxane, hexamethyldisiloxane, represented by the general formula R ³ -[SiMe ₂ -O-] _n - Linear polymers represented by SiMe ₂ R ³ and mixtures thereof, wherein n is 1 to 20, and R ³ is H, OH or optionally substituted alkyl, alkenyl, aryl, alkaryl or aralkyl.

In a preferred embodiment, the catalyst is selected from potassium hydroxide, sodium hydroxide, cesium hydroxide, lithium hydroxide, tetramethylammonium hydroxide, phosphazene, or silicon alkoxides of the foregoing substances. one or more.

In a preferred embodiment, the terminator is selected from one or more of the following: phosphoric acid, acetic acid, octanoic acid, tertiary amines with the general formula R ⁴ ₃ N, secondary amines with the general formula R ⁴ ₂ NH Amine, a primary amine of the general formula R ⁴ NH ₂ , where R ⁴ is an alkyl group having 2 to 10 carbon atoms, a silazane, or a silicon alkoxide of the foregoing.

In one embodiment of the invention, the organopolysiloxanes produced include α,ω-hydroxyl-terminated 107 gum, trimethylsiloxy-terminated polydimethylsiloxane, bis-vinyl-terminated Polydimethylsiloxane, bis-vinyl-terminated or methyl-terminated polydimethylsiloxane with a vinyl group in the middle segment, polydimethylsiloxane with Si-H bonds in the end group, Various organopolysiloxanes, such as polydimethylsiloxane, which is terminated by methyl or Si-H bonds and contains Si-H bonds in the middle segment.

The present invention provides a high-efficiency polymerization-termination device and method for continuously and efficiently producing organopolysiloxane, so as to solve various problems existing in the above-mentioned prior art.

The device of the invention has strong distribution and mixing ability, is easy to transfer mass and heat, allows materials to participate in the reaction evenly, is easy to feed and discharge, and has high production efficiency. It can effectively improve the efficiency of polymerization and termination reactions. At the same time, in the above process, the Due to sufficient stirring, tensile shear produces a large amount of liquid film and the surface renewal rate is fast. The large mass transfer area helps to remove volatile matter quickly and efficiently. Various types of organopolysiloxanes can be continuously produced using the device and method of the present invention, and the viscosity range is accurately controllable between 300-20,000,000 cP. In addition, the obtained product has a narrow molecular weight distribution, low inorganic salt impurity content, high thermal stability, and a volatile content of less than 0.5%. More importantly, the ability to maintain a narrow molecular weight distribution over a very broad molecular weight/viscosity range.

The polymerization-termination device for continuous production of organopolysiloxane of the present invention is low in complexity and consists of only two directly connected reactors (such as twin-screw extruders), thereby saving production space and facilitating production control. All processes involved in the organopolysiloxane production process can be continuously performed and completed quickly in this set of equipment, which greatly improves the time and space efficiency of the equipment. The material sequentially completes the polymerization reaction and optional partial devolatilization in reactor 1, and completes the termination reaction and deep devolatilization in reactor 2. The two reactors are directly connected, so the material transfer time can be almost ignored, the efficiency is higher, and the reaction can be terminated in a more timely manner, which facilitates real-time and accurate control of the polymer molecular weight and viscosity. Compared with the prior art process, the present invention can achieve synchronous devolatilization, eliminating the additional time-consuming and energy-consuming devolatilization process, and greatly saving production time.

The device of the present invention can prepare linear polysiloxanes with a very wide viscosity range. On the one hand, low-viscosity polysiloxane can be produced because the device is simple to connect and not prone to leakage. On the other hand, high-viscosity polysiloxanes can also be prepared due to the efficient mixing of the twin-screw extruder, which allows effective mass and heat transfer and avoids back-mixing. More importantly, the device of the present invention can quickly function as a terminator, thereby achieving precise control of product viscosity/molecular weight.

In addition, the device of the present invention does not leave sediment materials inside the equipment, can directly switch production lines without causing contamination to the product, and facilitates the preparation of various types of organopolysiloxanes. The organopolysiloxane produced according to the device and method of the present invention has the following excellent qualities at the same time: small molecular weight/viscosity fluctuations, uniform molecular weight distribution, extremely low volatile matter, low inorganic salt impurity content, and good thermal stability and long-term storage stability. .

If traditional screws are added to static mixers and other equipment, their sealing performance may be reduced to a certain extent due to multi-pipeline connections, and the twin screws in the static mixer cannot achieve sealing and maintain vacuum when loading low-viscosity materials. Meet the preparation conditions for low-viscosity polysiloxane. On the contrary, in the present invention, two twin-screw reactors are directly connected in series, which reduces pipeline connections and avoids the installation of additional sealing interfaces. Sealing and high vacuum can be maintained throughout the production process, which is beneficial to the preparation of low-viscosity Organopolysiloxane.

This invention does not use a static mixer, which is difficult to accurately control the product viscosity in real time, but uses the excellent stirring ability of the twin-screw to quickly and fully mix and react the materials with the catalyst and terminator, making the polymerization reaction instantly controllable. Polymers of various viscosities can be obtained accurately.

In one embodiment of the present invention, a screw extruder for efficient polymerization of siloxane and a screw extruder for efficient termination of polymerization are directly connected in series, realizing a flexible combination of reactors with different functions and saving production. space and short material transfer time.

Overall, the polymerization-termination device and method for continuously producing organopolysiloxane according to the present invention have the following advantages.

a) Wide applicability: The entire device of the present invention has excellent distribution and mixing capabilities when preparing various types of organopolysiloxanes such as low viscosity, high viscosity or raw rubber. The heat and mass transfer process is fast and uniform, and can make various The reaction materials are mixed evenly, the reaction is complete in a short residence time, and there is a stable plug flow in the axial direction without back-mixing, making the prepared polymer evenly distributed and suitable for continuous production;

b) Strong controllability: The initial polymerization product in reactor 1 is directly transported to reactor 2 for terminating the reaction, without intermediate residence time; using the excellent stirring ability of the twin-screw, the materials, catalyst, and terminator are quickly and fully mixed The mixing and reaction make the polymerization reaction instantly controllable, and polymers of various viscosities can be accurately obtained;

c) Excellent process: During the mixing process, the twin-screw extruder can form a large number of extremely thin liquid films through strong stretching and shearing, increasing the specific surface area of the product, helping to form a gas-liquid interface for mass transfer, and thus Low boiling matter is discharged, and these liquid films can continue to mix with the materials in the cavity to form new liquid films, that is, the surface renewal rate is fast, which strengthens the gas-liquid mass transfer process, and the final devolatilization effect is excellent;

d) Functional modularization: Two twin-screw extruders are used for polymerization reaction, termination reaction and devolatilization process respectively, which facilitates the control of each process separately. Simple parameter changes can obtain different polymerization effects and degassing effects. product.

Description of the drawings

Figure 1 is a schematic diagram of a polymerization-termination device and method for continuously producing organopolysiloxane according to an embodiment of the present invention.

Detailed ways

As shown in Figure 1, the polymerization-termination device for continuous production of organopolysiloxane of the present invention includes:

Reactor 1, which is used to efficiently carry out the polymerization reaction of siloxane;

Reactor 2, which is directly connected to the outlet of reactor 1 and used to efficiently terminate the polymerization reaction;

In certain embodiments of the present invention, reactors 1 and 2 used in the polymerization-termination device of the present invention can be twin-screw extruders respectively, which can also be replaced by other types of continuous paddle extrusion equipment. In certain embodiments of the invention, the twin-screw extruder 1 has a feed port, a vent, a discharge port and an exhaust port. The feed port of the twin-screw extruder 1 is connected to various raw material storage tanks. In certain embodiments of the present invention, the twin-screw extruder 1 is a co-rotating or counter-rotating twin-shaft extrusion reactor. In some embodiments of the present invention, the feeding mode of the twin-screw extruder 1 used for polymerization is: feeding from the head of the extruder 1, discharging from the barrel outlet at the tail of the screw, and The outlet is directly connected to the twin-screw extruder 2 used to terminate the polymerization reaction. The barrel of the twin-screw extruder 1 is closed, thereby establishing a high vacuum environment to improve the sealing performance of the reactor 1 .

In certain embodiments of the invention, the twin-screw extruder 1 includes:

Twin-screw extruder body; a feed port is provided at the barrel of the screw head of the twin-screw extruder, and a discharge port is provided at the barrel of the screw tail. The discharge port is connected to the twin-screw extruder. Machine 2 is directly connected;

The present invention has no special restrictions on the structure of the twin-screw extruder body, which can be any combination of various barrels, screws and threaded elements well known to those skilled in the art.

In certain embodiments of the present invention, the screw diameter of the twin-screw extruder body is 36 to 240 mm, and the aspect ratio of the screw is 18 to 60:1. Preferably, the screw diameter of the twin-screw extruder body is 240 mm, and the screw length-to-diameter ratio is 28:1.

In certain embodiments of the present invention, linear siloxane, cyclic siloxane or a mixture of both, an end-capping agent and a catalyst as reaction raw materials are charged into the feed port of the twin-screw extruder 1 , after the raw materials are mixed and heated evenly in the twin-screw extruder 1, with the twin-screw stirring, the material is gradually transported forward and the polymerization reaction of siloxane occurs at the same time, and then the initial material after polymerization is extruded from the twin-screw The discharge port of discharge machine 1 directly enters twin-screw extruder 2. That is, in the working state, the reaction raw materials enter from the feed port of the twin-screw extruder 1 body, polymerization occurs, and the polymerized material is discharged from the discharge port.

The twin-screw extruder 1 also includes a devolatilization chamber. The devolatilization chamber is arranged on the barrel of the twin-screw extruder 1 body. When the forward-moving material passes through the cylinder section equipped with a devolatilization chamber, it is devolatilized under vacuum conditions, and the low-boiling materials are discharged through the exhaust port of the devolatilization chamber. The devolatilized material is discharged through the discharge port of the twin-screw extruder 1, and the volatile matter is discharged from the exhaust port of the devolatilization chamber.

The more common form of reactor 2 used in the polymerization-termination device of the present invention is a twin-screw extruder. In the embodiment of the present invention, the twin-screw extruder 2 is provided with a feed port, a terminator injection port, a discharge port and an exhaust port. The feed port of the twin-screw extruder 2 is directly connected to the discharge port of the reactor 1. In certain embodiments of the present invention, reactor 2 is a devolatilization twin-screw extruder with co-rotating or counter-meshing twin-screw extruders.

In some embodiments of the present invention, the feeding mode of reactor 2 is: feeding from the connection between the screw tail and reactor 1, and discharging from the barrel of the screw head. The barrel of the reactor 2 is a closed barrel, so that a high vacuum environment can be established to help improve the sealing performance of the screw.

In certain embodiments of the invention, the devolatilization twin-screw extruder 2 includes:

The body of the twin-screw extruder; the barrel at the tail of the screw is provided with a feed port directly connected to the reactor 1, and the barrel at the head of the screw is provided with a discharge port;

A devolatilization chamber provided on the barrel of the devolatilization twin-screw extruder body.

The present invention has no special restrictions on the structure of the twin-screw extruder body, which may include various barrels, screws and threaded elements well known to those skilled in the art, and any combination thereof. In some embodiments of the present invention, the screw diameter of the twin-screw extruder body is 36 to 240 mm, and the aspect ratio of the screw is 36 to 60:1. Preferably, the screw diameter of the twin-screw extruder body is 55 mm, and the screw length-to-diameter ratio is 38:1.

In the working state, the reaction material discharged from the outlet of reactor 1 enters from the inlet of reactor 2 and is evenly mixed with the terminator, thereby terminating the polymerization reaction. At the same time, the material forms an extremely thin liquid film with an extremely large specific surface area under strong stretching and shearing, which facilitates mass transfer and removal of low boiling matter at the gas-liquid interface. Continuous stirring can form a new liquid film, and the interface renewal rate is fast, which strengthens the mass transfer power in low boiling removal, thus strengthening the discharge of the devolatilized organopolysiloxane product from the outlet of reactor 2 discharge.

The devolatilization twin-screw extruder also includes a devolatilization chamber. The devolatilization chamber is arranged on the barrel of the twin-screw extruder body. When the forward-moving material passes through the cylinder section equipped with a devolatilization chamber, it undergoes enhanced devolatilization under vacuum conditions, and the volatile components are discharged through the exhaust port of the devolatilization chamber. The devolatilized organopolysiloxane product is discharged through the discharge port of the reactor 2, and the volatile matter is discharged from the exhaust port of the devolatilization chamber of the reactor 2.

The present invention also relates to a method for continuously producing organopolysiloxane using the above-mentioned polymerization-termination device, comprising the following steps:

a) The siloxane including linear siloxane, cyclic siloxane or a mixture of the two is treated together with an end-capping agent and a catalyst. Load into reactor 1 through the feed port;

b) The feed materials are rapidly mixed and heated uniformly in reactor 1 to perform the polymerization reaction of siloxane;

c) Feed the initial polymerization product leaving reactor 1 to reactor 2 and quickly mix it with the terminator to terminate the polymerization reaction;

d) Deeply devolatilize the material in reactor 2 to obtain organopolysiloxane.

In certain embodiments of the present invention, the siloxane used as the raw material may be a linear siloxane or a cyclic siloxane of the chemical formula -(SiR ¹ R ² -O-) _n or a mixture of the two, wherein, n is 1 to 500, preferably n is 2 to 100, and R ¹ and R ² are H or an optionally substituted alkyl group, alkenyl group, aryl group, alkaryl group or aralkyl group, etc. In certain embodiments of the present invention, the feed rate of the silicone raw material is 50-400kg/h, preferably 200kg/h, more preferably 150kg/h.

In certain embodiments of the invention, the catalyst is one or more catalysts selected from the group consisting of potassium hydroxide, sodium hydroxide, cesium hydroxide, lithium hydroxide, tetramethylammonium hydroxide, phosphazene Catalysts, or silicon alkoxides of the above substances. In certain embodiments of the present invention, the feed amount of the catalyst solution is 0.01-2kg/h. In certain embodiments, the feed rate of the catalyst solution is 0.05-1 kg/h.

In certain embodiments of the invention, the end-capping agent is selected from divinyltetramethyldisiloxane, hexamethyldisiloxane, represented by the general formula R ³ -[SiMe ₂ -O-] _n Linear polymers represented by SiMe ₂ R ³ and mixtures thereof, wherein n is 1 to 20, and R ³ is H, OH or optionally substituted alkyl, alkenyl, aryl, alkaryl or aralkyl. In certain embodiments of the present invention, the feeding amount of the capping agent is 0.2-15kg/h. In certain embodiments, the feed rate of the capping agent is 1-10 kg/h.

The feed is polymerized in reactor 1 (such as a twin-screw extruder) to obtain a polymerized initial product.

In some embodiments of the present invention, the screw barrel temperature of reactor 1 is 23-200°C. In some embodiments, the screw barrel temperature of the reactor 1 is 100-150°C. In some embodiments of the present invention, the screw speed of reactor 1 is 10-600 rpm. In certain embodiments, reactor 1 is a polymerization twin-screw extruder with a screw speed of 200 rpm. In some embodiments of the present invention, the polymerization reaction in reactor 1 is performed under a vacuum of 50 to 50,000 Pa.

In certain embodiments of the invention, the terminator is phosphoric acid, acetic acid, octanoic acid, a tertiary amine with the general formula R ⁴ ₃ N, and a secondary amine with the general formula R ⁴ ₂ NH, with the general formula R ⁴ NH ₂ For primary amines, R ⁴ is one or more of an alkyl group with 2-10 carbon atoms, silazane or silicon alkoxide of the above materials. In certain embodiments of the invention, the feed of terminator solution The amount is 0.02~5kg/h.

The polymerized initial product is extruded from reactor 1 and fed to reactor 2 (such as twin-screw extruder 2), where it is evenly mixed with the terminator to terminate the polymerization reaction. At the same time, the materials in reactor 2 are deeply devolatilized under stirring, high vacuum and high temperature to discharge low boilers and obtain organopolysiloxane products.

In some embodiments of the present invention, the barrel temperature of the screw section of the reactor 2 is 20 to 180°C. Preferably, the temperature of the barrel of the screw section is 120°C. In some embodiments of the present invention, the screw speed of the reactor 2 is 10-600 rpm, preferably, the screw speed is 100 rpm. In some embodiments of the present invention, the vacuum degree of reactor 2 is 100 to 10,000 Pa.

The present invention has no special restrictions on the feed source of the above-mentioned reactor 1, and it can come from commercially available products.

The feed containing siloxane, capping agent and catalyst is transported to the feed port of reactor 1 via a metering pump and loaded into it. Under the action of vigorous stirring and kneading, the feed materials are quickly mixed evenly and heated to the reaction temperature, and polymerization begins under the action of the catalyst. Due to the mixing process produced by the screw stirring, the materials can be quickly mixed and reacted completely in the radial distribution, while the axial push will not affect the distributed mixing. That is, there is almost no back-mixing between materials at adjacent locations and no mutual influence. During this process, various by-products generated by the polymerization reaction, including some low-boiling substances, can also be desorbed from the liquid film interface generated during the distribution mixing process and discharged from the devolatilization chamber. The obtained unterminated polymerization initial product is continuously transported to the reactor 2 and mixed evenly with the terminator to terminate the polymerization reaction. During the termination process, the residual low-boiling substances are released from the interior of the polymer under the combined effects of high temperature, low pressure, large mass transfer area, and fast interface renewal rate, and are removed through the devolatilization chamber of reactor 2 to obtain different properties. The viscosity range is precisely controllable and ultra-low volatile organopolysiloxane product.

The following examples are only intended to illustrate the present invention and are not intended to limit the present invention.

Example 1

This embodiment provides a polymerization-termination device for continuous production of organopolysiloxane as shown in Figure 1, including:

Twin-screw extruder1 for efficient silicone polymerization;

A twin-screw extruder 2 directly connected to the discharge port of the twin-screw extruder 1 for efficiently terminating the polymerization reaction;

Among them, the twin-screw extruder 1 includes:

Twin-screw extruder body; a feed port is provided at the barrel of the screw head of the body, and a feed port is provided at the barrel at the tail of the screw. There is a discharge port provided;

A devolatilization chamber provided on the barrel of the twin-screw extruder body.

The screw diameter of the twin-screw extruder body is 240mm, and the aspect ratio of the screw is 28:1.

Twin screw extruder 2 includes:

Twin-screw extruder body; a feed port is provided at the screw tail barrel, and a discharge port is provided at the screw head barrel;

A devolatilization chamber provided on the main body barrel of the twin-screw extruder.

The screw diameter of the twin-screw extruder body is 55mm, and the aspect ratio of the screw is 38:1.

The polymerization-termination method for continuous production of polysiloxane using the above device includes:

1) Use continuous transportation to transport the feed including linear siloxane, catalyst and end-capping agent to the twin-screw extruder 1 through the feed port of the reactor 1. The feed is mixed and heated to start the polymerization reaction. At the same time, the volatile matter is removed to obtain the polymerized initial product;

The chemical formula of the linear siloxane is HO-[SiMe ₂ -O-] _n H, where n is 1 to 500, and the feed rate is 150kg/h; the catalyst is trimethylsiloxane of phosphazene base catalyst (effective mass concentration is 0.1wt.%), the feed rate is 0.75kg/h; the chemical formula of the end-capping agent is Vi(SiMe ₂ O) _n SiMe ₂ Vi, where n is 1 to 20, and Me represents formazan Base, Vi represents vinyl. The feed rate is 10kg/h, the average screw barrel temperature of the twin-screw extruder 1 is 120°C, the screw speed is 100rpm, and the vacuum degree is 500-2,000Pa.

2) Discharge the polymerized initial product obtained in step 1) from the outlet of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying manner at a rate of 0.75kg/h. The terminator is continuously transported into the twin-screw extruder 2 to terminate the polymerization reaction. The terminator is a tri-n-propylamine solution (mass concentration 0.2wt.%) in Vi(SiMe ₂ O) _n SiMe ₂ Vi with a viscosity of 350 cp. The material undergoes deep devolatilization while terminating the polymerization reaction in the twin-screw extruder 2. The average temperature of the screw barrel is 160°C, the screw speed is 100 rpm, and the vacuum degree is 200-1,000 Pa. Finally, ultra-low volatile organic matter is obtained. Polysiloxane products.

Example 2

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

The body of the twin-screw extruder; a feed port is provided at the barrel of the screw head of the body, and a discharge port is provided at the barrel of the screw tail;

The screw diameter of the twin-screw extruder body is 300mm, and the aspect ratio of the screw is 16:1.

Twin screw extruder 2 includes:

The screw diameter of the twin-screw extruder body is 35mm, and the aspect ratio of the screw is 68:1.

1) Use continuous transportation to transport the feed including the siloxane ring mixture, catalyst and end-capping agent to the twin-screw extruder 1 through the feed port of the reactor 1, and start after the feed is mixed and heated The polymerization reaction simultaneously devolatilizes to obtain the polymerized initial product;

The siloxane ring is a mixture of chemical formulas [SiMe ₂ O] _n and [SiMeViO] _n , where n is 3 to 50, and the feed amount is 200kg/h; the catalyst is potassium silanolate (mass concentration is 15wt.%), the feed rate is 0.015kg/h; the chemical formula of the end-capping agent is Vi(SiMe ₂ O) _n SiMe ₂ Vi, where n is 1 to 20, the feed rate is 5.20kg/h, twin-screw The average temperature of the screw barrel of extruder 1 is 160°C, the screw speed is 150 rpm, and the vacuum degree is 10,000-50,000 Pa.

2) Discharge the polymerized initial product obtained in step 1) from the discharge port of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying manner, and at the same time, add the terminator silicon alkoxide phosphate The material is continuously transported into the twin-screw extruder 2 at a rate of 0.025kg/h (mass concentration 9wt.%) to terminate the polymerization reaction. The material undergoes deep devolatilization while terminating the polymerization reaction in the twin-screw extruder 2. The screw The average temperature of the cylinder is 180°C, the screw speed is 100rpm, and the vacuum degree is 100-300Pa. Finally, an ultra-low volatile organopolysiloxane product is obtained.

Example 3

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

The chemical formula of the linear siloxane is HO-[SiMe ₂ -O-] _n H, where n is 1 to 500, and the feed amount is 100kg/h; the catalyst is an ethyl acetate solution of phosphazene (mass The concentration is 0.2wt.%), the feeding amount is 0.50kg/h; the chemical formula of the end-capping agent is Vi(SiMe ₂ O) _n SiMe ₂ Vi, where n is 1 to 20, and the feeding amount is 3.40kg/h , the average temperature of the screw barrel of the twin-screw extruder 1 is 130°C, the screw speed is 100rpm, and the vacuum degree is 500-1,000Pa.

2) Discharge the polymerized initial product obtained in step 1) from the discharge port of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying mode, and at the same time, add the terminator trinonylamine Ethyl acetate solution at 1.00kg/h (mass concentration 0.2wt.%) is continuously transported into the twin-screw extruder 2 to terminate the polymerization reaction. The material is deeply devolatilized while terminating the polymerization reaction in the twin-screw extruder 2. The average temperature of the screw barrel The temperature is 170℃, the screw speed is 130rpm, and the vacuum degree is 200-500Pa. Finally, an ultra-low volatile organopolysiloxane product is obtained.

Example 4

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

The screw diameter of the twin-screw extruder body is 75mm, and the length-to-diameter ratio of the screw is 52:1.

The chemical formula of the linear siloxane is HO-[SiMe ₂ -O-] _n H, where n is 1 to 500, and the feed amount is 150kg/h; the catalyst is a toluene solution of phosphazene (mass concentration: 0.08wt.%), the feed rate is 0.56kg/h; the chemical formula of the end-capping agent is Me(SiMe ₂ O) _n SiMe ₃ , where n is 1 to 20, the feed rate is 2.35kg/h, twin-screw squeeze The average temperature of the screw cylinder coming out of machine 1 is 100℃, the screw speed is 80rpm, and the vacuum degree is 1000-5,000Pa.

2) Discharge the polymerized initial product obtained in step 1) from the outlet of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying mode, and at the same time, add the terminator silazane The toluene solution is continuously transported into the twin-screw extruder 2 at a rate of 0.45kg/h (mass concentration 0.2wt.%) to terminate the polymerization reaction. The material is subjected to deep dehydration while terminating the polymerization reaction in the twin-screw extruder 2. The average temperature of the screw barrel is 170°C, the screw speed is 150rpm, and the vacuum degree is 200-500Pa. Finally, an ultra-low volatile organopolysiloxane product is obtained.

Example 5

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

1) The feed including siloxane ring body, catalyst and end-capping agent is transported to the twin-screw extruder 1 through the feed port of the reactor 1 by continuous transportation. The feed is mixed and heated to start polymerization. The reaction simultaneously devolatilizes and obtains the polymerized initial product;

The chemical formula of the siloxane ring is [SiMe ₂ O] _n , where n is 3 to 50, and the feed rate is 150kg/h; the catalyst is the silicon alkoxide of tetramethylammonium hydroxide (mass concentration is 10wt.%), the feed rate is 0.015kg/h; the chemical formula of the end-capping agent is Vi(SiMe ₂ O) _n SiMe ₂ Vi, where n is 1 to 20, the feed rate is 2.71kg/h, double The average temperature of the screw barrel of the screw extruder 1 is 120°C, the screw speed is 120 rpm, and the vacuum degree is 10,000-50,000 Pa.

2) Discharge the polymerized initial product obtained in step 1) from the outlet of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying manner. In 2, the temperature of the material rises, and tetramethylammonium hydroxide is thermally decomposed to terminate the polymerization reaction. The material undergoes deep devolatilization while terminating the polymerization reaction in the twin-screw extruder 2. The average temperature of the screw barrel is 160°C. The screw speed is 50 rpm and the vacuum degree is 100-300 Pa. Finally, an ultra-low volatile organopolysiloxane product is obtained.

Example 6

Twin-screw extruder1 for efficient silicone polymerization;

Twin screw extruder 1 includes:

Twin screw extruder 2 includes:

1) The feed including linear siloxane and catalyst is transported to the twin-screw extruder 1 through the feed port of the reactor 1 by continuous transportation. After the feed is mixed and heated, the polymerization reaction starts and the volatile matter is devolatilized. , to obtain the polymerized initial product;

The chemical formula of the linear siloxane is HO-[SiMe ₂ -O-] _n H, where n is 1 to 500, and the feed amount is 150kg/h; the catalyst is an ethyl acetate solution of phosphazene (mass The concentration is 0.1wt.%), the feed rate is 0.45kg/h; the average temperature of the screw barrel of the twin-screw extruder 1 is 80°C, the screw speed is 120rpm, and the vacuum degree is 3000-10,000Pa.

2) Discharge the polymerized initial product obtained in step 1) from the discharge port of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying mode, and at the same time, add the terminator tri-n-butylamine The ethyl acetate solution is continuously transported into the twin-screw extruder 2 at a rate of 0.90kg/h (mass concentration 0.1wt.%) to terminate the polymerization reaction. While the material is being terminated in the twin-screw extruder 2, the polymerization reaction is terminated. After deep devolatilization, the average temperature of the screw barrel is 170°C, the screw speed is 150rpm, and the vacuum degree is 300-1,000Pa, finally obtaining an ultra-low volatile organopolysiloxane product.

Example 7

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

1) Use continuous transportation to transport the feed including the mixture of siloxane ring and linear siloxane, catalyst and end-capping agent to the twin-screw extruder 1 through the feed port of the reactor 1, and feed After mixing and heating, the polymerization reaction starts and the volatile matter is removed simultaneously to obtain the polymerized initial product;

The chemical formula of the linear siloxane is HO-[SiMe ₂ -O-] _n H, where n is 1 to 500, and the chemical formula of the siloxane ring is [SiMe ₂ O] _n , where n is 3 to 50, the two are mixed in a certain proportion, the feed rate is 200kg/h; the catalyst is alkali gum of potassium silanolate (effective mass concentration is 5wt.%), the feed rate is 0.04kg/h; end-capping The chemical formula of the agent is Vi(SiMe ₂ O) _n SiMe ₂ Vi, where n is 1 to 20, the feed rate is 2.40kg/h, the average screw barrel temperature of the twin-screw extruder 1 is 160°C, and the screw speed is 150rpm, vacuum degree is 10,000-50,000Pa.

2) The polymerized initial product obtained in step 1) is discharged from the discharge port of the twin-screw extruder 1 and directly transported into the twin-screw extruder 2 in a continuous conveying manner. At the same time, the terminator octanoic acid silanol hydrochloride is added The glue is continuously transported into the twin-screw extruder 2 at a rate of 0.04kg/h (mass concentration 5wt.%) to terminate the polymerization reaction. The material is deeply devolatilized while terminating the polymerization reaction in the twin-screw extruder 2. The average temperature of the screw barrel is 180°C, the screw speed is 50 rpm, and the vacuum degree is 100-300 Pa. Finally, an ultra-low volatile organopolysiloxane product is obtained.

Example 8

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

The chemical formula of the linear siloxane is HO-[SiMe ₂ -O-] _n H, where n is 1 to 500, and the feed rate is 150kg/h; the catalyst is a tetrachloroethane solution of phosphazene ( The mass concentration is 0.1wt.%), the feed rate is 0.45kg/h; the average temperature of the screw barrel of the twin-screw extruder 1 is 90°C, the screw speed is 90rpm, and the vacuum degree is 3000-10,000Pa.

2) Discharge the polymerized initial product obtained in step 1) from the outlet of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying mode, and at the same time, add the terminator silazane The tetrachloroethane solution is continuously transported into the twin-screw extruder 2 at a rate of 0.90kg/h (mass concentration 0.1wt.%) to terminate the polymerization reaction. The material is terminated in the twin-screw extruder 2 while the polymerization reaction is being terminated. After deep devolatilization, the average temperature of the screw barrel is 170°C, the screw speed is 100rpm, and the vacuum degree is 300-1,000Pa, finally obtaining an ultra-low volatile organopolysiloxane product.

Example 9

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

The siloxane ring has the chemical formula [SiMe ₂ O] _n , where n is 3 to 50, and the feed rate is 200kg/h; the catalyst is potassium silanolate alkali gum (mass concentration: 5wt.%), The feed rate is 0.04kg/h; the chemical formula of the end-capping agent is Vi(SiMe ₂ O) _n SiMe ₂ Vi, where n is 1 to 50, the feed rate is 3.40kg/h, the twin-screw extruder 1 The average temperature of the screw barrel is 160°C, the screw speed is 150rpm, and the vacuum degree is 10,000-50,000Pa.

2) Discharge the polymerized initial product obtained in step 1) from the outlet of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying manner, and at the same time, add the terminator phosphate silicon alkoxide The material is continuously transported into the twin-screw extruder 2 at a rate of 0.04kg/h (mass concentration 5wt.%) to terminate the polymerization reaction. The material is deeply devolatilized while terminating the polymerization reaction in the twin-screw extruder 2. The screw The average temperature of the cylinder is 180°C, the screw speed is 100rpm, and the vacuum degree is 100-300Pa. Finally, an ultra-low volatile organopolysiloxane product is obtained.

Example 10

Twin-screw extruder1 for efficient silicone polymerization;

A twin-screw extruder directly connected to the outlet of the twin-screw extruder 1 for efficiently terminating the polymerization reaction. Machine 2;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

The chemical formula of the siloxane ring is [SiMe ₂ O] _n , where n is 3 to 50, and the feed rate is 150kg/h; the catalyst is cesium hydroxide silicon alkoxide (mass concentration is 5wt. %), the feed rate is 0.03kg/h; the chemical formula of the end-capping agent is Me(SiMe ₂ O) _n SiMe ₃ , where n is 1 to 80, the feed rate is 3.53kg/h, twin-screw extruder The average temperature of the screw barrel of 1 is 120℃, the screw speed is 120rpm, and the vacuum degree is 10,000-50,000Pa.

2) The polymerized initial product obtained in step 1) is discharged from the discharge port of the twin-screw extruder 1 and directly transported into the twin-screw extruder 2 in a continuous conveying manner. At the same time, the terminator silicone acetate hydrochloride is added The glue is continuously transported into the twin-screw extruder 2 at a rate of 0.03kg/h (mass concentration 5wt.%) to terminate the polymerization reaction. The material is deeply devolatilized while terminating the polymerization reaction in the twin-screw extruder 2. The average temperature of the screw barrel is 180°C, the screw speed is 90 rpm, and the vacuum degree is 100-300 Pa. Finally, an ultra-low volatile organopolysiloxane product is obtained.

Example 11

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

The chemical formula of the linear siloxane is HO-[SiMe ₂ -O-] _n H, where n is 1 to 500, and the chemical formula of the siloxane ring is [SiMe ₂ O] _n , where n is 3 to 50, the two are mixed in a certain proportion, and the feed rate is 200kg/h; the catalyst is an n-hexane solution of phosphazene (effective mass concentration is 5wt.%), the feed rate is 0.04kg/h; end-capping The chemical formula of the agent is Me(SiMe ₂ O) _n SiMe ₃ , where n is 1 to 80, the feed rate is 2.30kg/h, the average temperature of the screw barrel of the twin-screw extruder 1 is 160°C, and the screw speed is 150rpm. , the vacuum degree is 10,000-50,000Pa.

2) Discharge the polymerized initial product obtained in step 1) from the discharge port of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying manner. At the same time, the terminator silicone phosphate hydrochloride is added The glue is continuously transported into the twin-screw extruder 2 at a rate of 0.03kg/h (mass concentration 6wt.%) to terminate the polymerization reaction. The material is extruded in the twin-screw In machine 2, deep devolatilization is performed while terminating the polymerization reaction. The average temperature of the screw cylinder is 180°C, the screw speed is 50 rpm, and the vacuum degree is 100-300 Pa. Finally, an ultra-low volatile organopolysiloxane product is obtained.

Example 12

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

The chemical formula of the linear siloxane is HO-[SiMe ₂ -O-] _n H, where n is 1 to 500, and the feed amount is 150kg/h; the catalyst is an ethyl acetate solution of phosphazene (mass The concentration is 0.1wt.%), the feed rate is 0.45kg/h; the average temperature of the screw barrel of the twin-screw extruder 1 is 100°C, the screw speed is 70rpm, and the vacuum degree is 3000-10,000Pa.

2) Discharge the polymerized initial product obtained in step 1) from the discharge port of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying mode, and at the same time, add the terminator trinonylamine The ethyl acetate solution is continuously transported into the twin-screw extruder 2 at a rate of 0.90kg/h (mass concentration 0.1wt.%) to terminate the polymerization reaction. The material is terminated in the twin-screw extruder 2 while the polymerization reaction is being terminated. After deep devolatilization, the average temperature of the screw barrel is 170°C, the screw speed is 80 rpm, and the vacuum degree is 300-1,000 Pa. Finally, an ultra-low volatile organopolysiloxane product is obtained.

Example 13

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

The siloxane ring body has the chemical formula [SiMe ₂ O] _n , where n is 3 to 50, and the feed rate is 180kg/h; The catalyst is silicon alkali gum of tetramethylammonium hydroxide (mass concentration: 5wt.%), and the feed rate is 0.05kg/h; the chemical formula of the end-capping agent is Vi(SiMe ₂ O) _n SiMe ₂ Vi, where , n is 1 to 80, the feed rate is 2.25kg/h, the average temperature of the screw barrel of the twin-screw extruder 1 is 120°C, the screw speed is 150rpm, and the vacuum degree is 10,000-50,000Pa.

2) Discharge the polymerized initial product obtained in step 1) from the outlet of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying manner. The temperature of the material in extruder 2 rises, and tetramethylammonium hydroxide is thermally decomposed to terminate the polymerization reaction. The material undergoes deep devolatilization while terminating the polymerization reaction in twin-screw extruder 2. The average temperature of the screw barrel is 160°C. , the screw speed is 120rpm, the vacuum degree is 100-300Pa, and finally an ultra-low volatile organopolysiloxane product is obtained.

Example 14

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

1) Continuously transport the feed including linear siloxane, catalyst and end-capping agent through the reactor 1 The feed port is transported to the twin-screw extruder 1. After the feed is mixed and heated, the polymerization reaction starts and the volatile matter is devolatilized to obtain the initial polymerized product;

The chemical formula of the linear siloxane is HO-[SiMe ₂ -O-] _n H, where n is 1 to 500, and the feed amount is 150kg/h; the catalyst is a toluene solution of phosphazene (mass concentration: 0.1wt.%), the feed rate is 0.75kg/h; the chemical formula of the end-capping agent is Me(SiMe ₂ O) _n SiMe ₃ , where n is 1 to 100, the feed rate is 3.10kg/h, twin-screw The average temperature of the screw barrel of extruder 1 is 120°C, the screw speed is 60 rpm, and the vacuum degree is 500-2,000 Pa.

2) Discharge the polymerized initial product obtained in step 1) from the outlet of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying mode, and at the same time, add the terminator silazane The toluene solution is continuously transported into the twin-screw extruder 2 at a rate of 0.75kg/h (mass concentration 0.1wt.%) to terminate the polymerization reaction. The material is subjected to deep dehydration while terminating the polymerization reaction in the twin-screw extruder 2. The average temperature of the screw barrel is 180°C, the screw speed is 120rpm, and the vacuum degree is 200-500Pa. Finally, an ultra-low volatile organopolysiloxane product is obtained.

Example 15

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

1) The feed including the linear siloxane mixture, catalyst and end-capping agent is transported to the twin-screw extruder 1 through the feed port of the reactor 1 by continuous transportation. The feed is mixed and heated to start polymerization. The reaction simultaneously devolatilizes and obtains the polymerized initial product;

The linear siloxane is a mixture of the chemical formula HO-[SiMe ₂ -O-] _m H and HO-[SiMe ₂ -O-] _n -[SiMeVi-O] _p H, where m, n, p are 10 ~100, the feed amount is 160kg/h; the catalyst is a dichloromethane solution of phosphazene (mass concentration is 0.2wt.%), the feed amount is 0.80kg/h; the chemical formula of the end-capping agent is Vi(SiMe ₂ O) _n SiMe ₂ Vi, where n is 1 to 80, the feed rate is 4.30kg/h, the average temperature of the screw barrel of the twin-screw extruder 1 is 130°C, the screw speed is 120rpm, and the vacuum degree is 300- 1,000Pa.

2) The polymerized initial product obtained in step 1) is discharged from the discharge port of the twin-screw extruder 1 and directly transported into the twin-screw extruder 2 in a continuous conveying manner. At the same time, the acetic acid of the terminator tripropylamine is added The ethyl ester solution is continuously transported into the twin-screw extruder 2 at a rate of 0.40kg/h (mass concentration 0.8wt.%) to terminate the polymerization reaction. The material is advanced in the twin-screw extruder 2 while terminating the polymerization reaction. After devolatilization, the average temperature of the screw barrel is 170°C, the screw speed is 100rpm, and the vacuum degree is 200-500Pa. Finally, an ultra-low volatile organopolysiloxane product is obtained.

Example 16

Twin-screw extruder1 for efficient silicone polymerization;

Among them, the twin-screw extruder 1 includes:

Twin screw extruder 2 includes:

The chemical formula of the linear siloxane is HO-[SiMe ₂ -O-] _n H, where n is 1 to 500, and the feed amount is 150kg/h; the catalyst is an ethyl acetate solution of phosphazene (mass The concentration is 0.1wt.%), the feed rate is 0.45kg/h; the average temperature of the screw barrel of the twin-screw extruder 1 is 110°C, the screw speed is 50rpm, and the vacuum degree is 3000-10,000Pa.

2) Discharge the polymerized initial product obtained in step 1) from the discharge port of the twin-screw extruder 1 and directly transport it into the twin-screw extruder 2 in a continuous conveying mode, and at the same time, add the terminator trinonylamine The ethyl acetate solution is continuously transported into the twin-screw extruder 2 at a rate of 0.90kg/h (mass concentration 0.1wt.%) to terminate the polymerization reaction. The material is terminated in the twin-screw extruder 2 while the polymerization reaction is being terminated. After deep devolatilization, the average temperature of the screw barrel is 170°C, the screw speed is 60 rpm, and the vacuum degree is 300-1,000 Pa, finally obtaining an ultra-low volatile organopolysiloxane product.

Example 17

The physical and chemical properties of various types of organopolysiloxanes with different viscosities prepared in Examples 1-16 were tested, and the test results are shown in Table 1:

Table 1 Various performance indicators of organopolysiloxane prepared in Examples 1-16

a. Define the temperature at which 5wt.% mass loss occurs in polysiloxane as its thermal decomposition temperature. Experimental conditions: heating rate The rate is 10℃/min, nitrogen atmosphere.

As can be seen from the above table, the organopolysiloxane product prepared by the device and method of the present invention has a wide viscosity range, low volatile matter, uniform molecular weight distribution, low inorganic salt content, good transparency, and high thermal stability.

Among them, Examples 6, 8, 12, and 16 prepared α,ω-dihydroxypolydimethylsiloxane with different viscosities. It uses linear siloxane, that is, low-viscosity α,ω-dihydroxypolydimethylsiloxane, as raw material, and is prepared by polycondensation without the addition of end-capping agent. Usually this reaction rate is fast, and traditional and existing technologies are difficult to control its viscosity/molecular weight in real time. Even after the terminator is added, the viscosity of the material will continue to increase because it is difficult to mix the two evenly. It depends greatly on the manufacturer's preparation experience. Only by adding the terminator in advance before the material reaches the required viscosity/molecular weight can the target product be obtained.

In this patent, the twin-screw reactor 2 is used for efficient polymerization termination reaction, and the residence time is usually controlled within 2 minutes, and in most cases is about 30 seconds. Therefore, compared with the traditional process and the static mixer termination process, the continuous dynamic mixing-termination process of the present invention not only has the advantages of high termination efficiency and small amount of termination required, but also makes it easier to control the viscosity/molecular weight of the product in real time. In the above embodiment, samples were taken from the tail end of the twin-screw extruder 1 (and the reaction was quickly quenched), and samples were taken from the outlet of the twin-screw extruder 2. It was found that the molecular weight distribution and viscosity were almost the same. No significant difference.

The comparison of sampling viscosity before and after termination of the reaction in the above-mentioned Examples 6, 8, 12, and 16 and the reaction parameters are shown in Table 2:

Table 2 Comparison before and after terminating the reaction of Examples 6, 8, 12, and 16

As can be seen from Table 2, thanks to the efficient and rapid termination reaction, when the product is pushed to the end of reactor 1, compared with the final product exiting from the end of reactor 2, there is no significant difference in properties such as viscosity and molecular weight distribution. . The above results show that the device and method of the present invention can achieve real-time control of the viscosity/molecular weight of organopolysiloxane (such as α,ω-dihydroxypolydimethylsiloxane).

Although the invention has been described with reference to one or more embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Additionally, all numerical values stated herein should be construed as if both precise values and approximations were expressly stated.

Claims

Polymerization-termination unit for continuous production of organopolysiloxanes, including:

Reactor 1, which is used for polymerization of siloxane;

The feed port of reactor 2 is connected with the discharge port of reactor 1 and is used to terminate the polymerization reaction.
The device according to claim 1, wherein the reactor 1 removes volatile matter while carrying out polymerization reaction, and/or the reactor 2 removes volatile matter while carrying out the termination of polymerization reaction.
The device according to claim 1, wherein the viscosity range of the produced organopolysiloxane is 300-20,000,000mPa·S, preferably 1,000-10,000mPa·S, more preferably 100,000-1,000,000mPa·S, even more preferably 3,000,000 -10,000,000mPa·S.
The device according to claim 1, wherein the produced organopolysiloxane has low volatile matter, preferably less than 0.5%, more preferably less than 0.3%.
The device according to claim 1, wherein the produced organopolysiloxane has a narrow molecular weight distribution, preferably 1.4-2.3, more preferably 1.5-2.0.
The device according to claim 1, wherein the produced organopolysiloxane has a low inorganic salt content, preferably <11 ppm, more preferably <0.1 ppm.
The device according to claim 1, wherein the produced organopolysiloxane has high thermal stability, preferably the thermal decomposition temperature is 380°C-510°C, and more preferably the thermal decomposition temperature is 385°C-470°C.
The device according to claim 1, characterized in that the reactor 1 is a co-rotating or counter-rotating twin-screw extruder 1, and the reactor 2 is a co-rotating or counter-rotating twin-screw extruder 2. .
According to the device of claim 1, a terminator feeding port is provided at the front end of the reactor 2.
The device according to claim 1, characterized in that the discharge port of the reactor 1 is directly connected to the feed port of the reactor 2, preferably in a straight line or vertically connected to each other or connected at other angles. .
The device according to claim 8, wherein the screw diameter of the twin-screw extruder 1 is 36-360mm, preferably 120-240mm.
The device according to claim 8, wherein the screw diameter of the twin-screw extruder 2 is 36-240mm, preferably 80-240mm.
The device according to claim 8, wherein the screw speed of the twin-screw extruder 1 is 1-200rpm, preferably 1-150rpm, more preferably 50-120rpm.
The device according to claim 8, wherein the screw speed of the twin-screw extruder 2 is 1-600rpm, preferably 1-150rpm, more preferably 60-150rpm.
The device according to claim 1, wherein the temperature of the reactor 1 is 20-180°C, preferably 110-150°C, more preferably 80-110°C.
The device according to claim 1, wherein the temperature of the reactor 2 is 20-180°C, preferably 100-170°C, more preferably 160-170°C.
The device according to claim 1, wherein the pressure of the reactor 2 is 0-50kPa, preferably 0-5kPa.
The polymerization-termination method for continuously producing organopolysiloxane using the device according to any one of claims 1-17 includes the following steps:

a) Sequentially add siloxane, end-capping agent and catalyst including linear siloxane or cyclic siloxane or a mixture of the two into reactor 1 to perform polymerization reaction while performing partial devolatilization to obtain the initial polymerized product;

b) Extrude the polymerized initial product from reactor 1 and transport it to reactor 2, where it is thoroughly mixed with the terminator to terminate the polymerization reaction while performing deep devolatilization to obtain organopolysiloxane .
The method according to claim 18, characterized in that the linear siloxane or cyclic siloxane in step a) has the following repeating structural unit - [SiR 1 R 2 -O-] n , where n It is 1 to 500, preferably 2 to 100, more preferably 3 to 20, and R 1 and R 2 are H or optionally substituted alkyl, alkenyl, aryl, alkaryl or aralkyl.
The method according to claim 18, characterized in that the end-capping agent is selected from divinyltetramethyldisiloxane, hexamethyldisiloxane, and is composed of the general formula R 3 -[SiMe 2 -O -] n Linear polymers represented by SiMe 2 R 3 and mixtures thereof, where n is 1 to 20, R 3 is H, OH or optionally substituted alkyl, alkenyl, aryl, alkaryl or aralkyl base.
The method according to claim 18, wherein the catalyst is selected from the group consisting of potassium hydroxide, sodium hydroxide, cesium hydroxide, lithium hydroxide, tetramethylammonium hydroxide, phosphazene, or silicon alkoxides of the foregoing substances. one or more.
The method according to claim 18, the terminator is selected from one or more of the following: phosphoric acid, acetic acid, octanoic acid, a tertiary amine with a general formula of R 4 3 N, a tertiary amine with the general formula of R 4 2 NH Amine, a primary amine of the general formula R 4 NH 2 , where R 4 is an alkyl group having 2 to 10 carbon atoms, a silazane, or a silicon alkoxide of the foregoing.