阅读说明：本技术 一种聚硅氧烷的连续化生产系统及生产方法 (Continuous production system and production method of polysiloxane ) 是由 郑智 刘继 朱晓英 于 2020-05-15 设计创作，主要内容包括：本发明涉及硅橡胶生产技术领域,尤其涉及一种聚硅氧烷的连续化生产系统及生产方法。所述聚硅氧烷的连续化生产系统包括：预混器；与所述预混器的出料口相连的聚合型双螺杆挤出机；与所述聚合型双螺杆挤出机的排气口相连的第一抽真空系统；与所述聚合型双螺杆挤出机的出料口相连的静态混合器；与所述静态混合器的出料口相连的落条式脱挥器；与所述落条式脱挥器的真空口相连的第二抽真空系统；与所述落条式脱挥器的出料口相连的脱挥型双螺杆挤出机；与所述脱挥型双螺杆挤出机的真空口相连的第三抽真空系统。最终生产得到的聚硅氧烷粘度较高,挥发分较低。(The invention relates to the technical field of silicone rubber production, in particular to a continuous production system and a continuous production method for polysiloxane. The continuous production system of the polysiloxane comprises: a premixer; a polymerization type double-screw extruder connected with the discharge port of the premixer; a first vacuum pumping system connected with an exhaust port of the polymerization type double-screw extruder; a static mixer connected with a discharge port of the polymerization type double-screw extruder; the falling strip type devolatilization device is connected with the discharge hole of the static mixer; the second vacuum pumping system is connected with the vacuum port of the falling strip devolatilizer; a devolatilization type double-screw extruder connected with a discharge port of the falling strip devolatilizer; and the third vacuum-pumping system is connected with a vacuum port of the devolatilization type double-screw extruder. The polysiloxane finally produced has high viscosity and low volatile component.)

1. A continuous production system for polysiloxanes, comprising:

a premixer;

a feeding port of the polymerization type double-screw extruder is connected with a discharging port of the premixer;

a first vacuum pumping system connected with an exhaust port of the polymerization type double-screw extruder;

the feed inlet of the static mixer is connected with the discharge outlet of the polymerization type double-screw extruder;

the feeding hole of the falling strip devolatilizer is connected with the discharging hole of the static mixer;

the second vacuum pumping system is connected with the vacuum port of the falling strip devolatilizer;

a devolatilization type double-screw extruder with a feed port connected with a discharge port of the falling strip devolatilizer;

and the third vacuum-pumping system is connected with a vacuum port of the devolatilization type double-screw extruder.

2. The continuous production system of claim 1, wherein the premixer is an in-line two-phase mixer;

the in-line two-phase mixer comprises:

the cylinder comprises an upper chamber and a lower chamber;

a stirring shaft penetrating through the upper chamber and extending to the lower chamber;

the double-layer frame blade paddles are arranged on the stirring shaft, the upper frame blade paddle of the double-layer frame blade paddles rotates around the stirring shaft in the upper cavity, and the lower frame blade paddle of the double-layer frame blade paddles rotates around the stirring shaft in the lower cavity; the blades of the double-layer frame blade paddle are provided with flow guide holes; a motor connected with a stirring shaft extending out of the upper cavity;

a siloxane feeding port is arranged on the side surface of the lower chamber;

the bottom of the lower chamber is provided with a head sealing agent feed opening and a catalyst feed opening;

and a discharge hole is formed in the side surface of the upper cavity.

3. The continuous production system according to claim 1, wherein the polymeric twin-screw extruder is a corotating twin-screw extruder;

the feeding mode of the polymerization type double-screw extruder is as follows: feeding materials from a barrel at the tail part of the screw, and discharging materials from a barrel at the root part of the screw;

the devolatilization type screw extruder is characterized in that the feeding mode is as follows: feeding from the tail part of a screw of the devolatilization type double-screw extruder, and discharging from the root part of the screw.

4. The continuous production system of claim 1, wherein the static mixer comprises one or more of a SMK type static mixer, a SMX type static mixer, a SMH type static mixer, and a SML type static mixer.

5. The continuous production system according to claim 1, wherein the first vacuum system is a first vacuum pump; the second vacuum pumping system is a second vacuum pump; the third vacuum-pumping system is a third vacuum pump.

6. A method for the continuous production of polysiloxanes, comprising the steps of:

A) premixing alpha, omega-dihydroxy polydimethylsiloxane and a catalyst solution to obtain a premix;

B) carrying out polymerization reaction on the premix in a polymerization type double-screw extruder, and terminating the polymerization reaction of the mixture after the polymerization reaction and a terminator solution in a static mixer to obtain an ultra-high viscosity polysiloxane crude product;

C) pre-devolatilizing the ultra-high viscosity polysiloxane crude product in a falling strip devolatilizer;

D) and carrying out secondary enhanced devolatilization on the pre-devolatilized ultrahigh-viscosity polysiloxane in a devolatilization type screw extruder to obtain polysiloxane.

7. The continuous production method according to claim 6, wherein in step A), the step A) is performedThe chemical formula of alpha, omega-dihydroxy polydimethylsiloxane is HO (Me)₂SiO)_mH, wherein m is 20-60; the feeding amount of the alpha, omega-dihydroxy polydimethylsiloxane is 40-400 kg/h;

the catalyst is selected from one of phosphazene, dodecyl benzene sulfonic acid and trifluoromethanesulfonic acid; the solvent in the catalyst solution is selected from ethyl acetate, dichloromethane or tetrachloroethane; the concentration of the catalyst solution is 5-20 g/L; the feeding amount of the catalyst solution is 0.02-0.2 kg/h;

the premixed raw materials also comprise a sealing head agent; the chemical formula of the end socket agent is Me (Me)₂SiO)_nMe or CH₂＝CH(Me₂SiO)_nCH＝CH₂Wherein n is 2-50; the feeding amount of the end sealing agent is 0.1-4 kg/h.

8. The continuous production method according to claim 6, wherein in the step B), the terminating agent is selected from one of diethylamine, tri-n-butylamine, trinonyl amine and silazane; the solvent in the terminator solution is selected from ethyl acetate, dichloromethane or tetrachloroethane; the mass solubility of the terminator solution is 5-20 g/L; the feeding amount of the terminator solution is 0.02-1 kg/h;

the vacuum degree of the polymerization reaction is 80-120 Pa;

the temperature of a screw barrel of the polymerization type double-screw extruder is 140-200 ℃, and the rotating speed of the screw is 90-150 rpm.

9. The continuous production method according to claim 6, wherein in the step C), the temperature of the pre-devolatilization is 140 to 160 ℃, and the vacuum degree of the pre-devolatilization is 60 to 100 Pa.

10. The continuous production method according to claim 6, wherein in the step D), the vacuum degree of the secondary enhanced devolatilization is 30-60 Pa;

the temperature of a cylinder body at the screw section of the devolatilization type screw extruder is 160-220 ℃, and the rotating speed of the screw is 110-170 rpm.

Technical Field

The invention relates to the technical field of silicone rubber production, in particular to a continuous production system and a continuous production method for polysiloxane.

Background

27.6.2018, European chemical administration (ECHA) officially published a newly added 19 th batch of 10 SVHC cleaners on the official networkMono, in which D is₄、D₅And D₆High interest is included, requiring individual content < 0.1%. With increasing demands on the level of environmental and health protection, reducing the potential risks of D4, D5, and D6 and providing risk-reducing measures, more is being moved to the manufacturer.

The synthesis of the ultrahigh viscosity polysiloxane mostly adopts a catalytic equilibrium process, and the used equipment is a polymerization kettle. In order to obtain polysiloxanes with very high viscosities, prolonged polymerization times and run-down times are generally used in production. 12-15% octamethylcyclotetrasiloxane (D) is present after the reaction is finished₄) Decamethylcyclopentasiloxane (D)₅) And dodecamethylcyclohexasiloxane (D)₆) And Volatile Organic Compounds (VOCs) to be removed. This preparation method has the following drawbacks: 1) the stirring system is high in requirement, and the fluidity is poor along with the increase of the viscosity of the polymer, so that the stirring is insufficient, the local overheating is caused, and the crosslinking or yellowing is generated. 2) The viscosity is high, and the material is not easy to discharge. 3) The volatile component of the product is higher, generally 1-3%.

Chinese patent application No. 201310331091.2 entitled "production method and production system for continuously producing 107 glue by twin-screw" discloses that dimethylcyclosiloxane is dehydrated by a dehydration kettle, a static mixer is used for mixing and dispersing catalyst, degradation is carried out in a degradation device, and 50000cp107 glue is continuously prepared by screw devolatilization discharging. Chinese patent application No. 200910193006.1 entitled "preparation method of polyorganosiloxane with ultra-high molecular weight" discloses a reactor with S-shaped stirring, which takes dimethylcyclosiloxane or alpha, omega-dihydroxy polydimethylsiloxane as raw material to intermittently prepare the polyorganosiloxane with ultra-high molecular weight, and the generated volatile components are high. The invention provides a production device of ultrahigh molecular weight polysiloxane, which is named as 'production device of ultrahigh molecular weight polysiloxane' and discloses that polymerization is carried out in a polymerization kettle, a static mixer is used for removing low, a screw extruder is used for removing low for the second time, and the lowest volatile component of the ultrahigh molecular weight polysiloxane prepared by reaction can reach 0.6%. Chinese patent application No. 201721186548.5 entitled "simple production device for ultrahigh molecular weight polysiloxane" discloses a reactor with an S-shaped strong stirring device for preparing ultrahigh molecular weight polysiloxane.

Disclosure of Invention

In view of the above, the present invention provides a continuous production system and a continuous production method for polysiloxane, which can obtain polysiloxane with higher viscosity and lower volatile component.

The invention provides a continuous production system of polysiloxane, which comprises:

a premixer;

a feeding port of the polymerization type double-screw extruder is connected with a discharging port of the premixer;

a first vacuum pumping system connected with an exhaust port of the polymerization type double-screw extruder;

the feed inlet of the static mixer is connected with the discharge outlet of the polymerization type double-screw extruder;

the feeding hole of the falling strip devolatilizer is connected with the discharging hole of the static mixer;

the second vacuum pumping system is connected with the vacuum port of the falling strip devolatilizer;

a devolatilization type double-screw extruder with a feed port connected with a discharge port of the falling strip devolatilizer;

and the third vacuum-pumping system is connected with a vacuum port of the devolatilization type double-screw extruder.

Preferably, the premixer is an in-line two-phase mixer;

the in-line two-phase mixer comprises:

the cylinder comprises an upper chamber and a lower chamber;

a stirring shaft penetrating through the upper chamber and extending to the lower chamber;

the double-layer frame blade paddles are arranged on the stirring shaft, the upper frame blade paddle of the double-layer frame blade paddles rotates around the stirring shaft in the upper cavity, and the lower frame blade paddle of the double-layer frame blade paddles rotates around the stirring shaft in the lower cavity; the blades of the double-layer frame blade paddle are provided with flow guide holes; a motor connected with a stirring shaft extending out of the upper cavity;

a siloxane feeding port is arranged on the side surface of the lower chamber;

the bottom of the lower chamber is provided with a head sealing agent feed opening and a catalyst feed opening;

and a discharge hole is formed in the side surface of the upper cavity.

Preferably, the polymerization type twin-screw extruder is a co-rotating intermeshing type twin-screw extruder;

the feeding mode of the polymerization type double-screw extruder is as follows: feeding materials from a barrel at the tail part of the screw, and discharging materials from a barrel at the root part of the screw;

the devolatilization type screw extruder is characterized in that the feeding mode is as follows: feeding from the tail part of a screw of the devolatilization type double-screw extruder, and discharging from the root part of the screw.

Preferably, the static mixer comprises one or more of an SMK type static mixer, an SMX type static mixer, an SMH type static mixer and an SML type static mixer.

Preferably, the first vacuum-pumping system is a first vacuum pump; the second vacuum pumping system is a second vacuum pump; the third vacuum-pumping system is a third vacuum pump.

The invention also provides a continuous production method of polysiloxane, which comprises the following steps:

A) premixing alpha, omega-dihydroxy polydimethylsiloxane and a catalyst solution to obtain a premix;

B) carrying out polymerization reaction on the premix in a polymerization type double-screw extruder, and terminating the polymerization reaction of the mixture after the polymerization reaction and a terminator solution in a static mixer to obtain an ultra-high viscosity polysiloxane crude product;

C) pre-devolatilizing the ultra-high viscosity polysiloxane crude product in a falling strip devolatilizer;

D) and carrying out secondary enhanced devolatilization on the pre-devolatilized ultrahigh-viscosity polysiloxane in a devolatilization type screw extruder to obtain polysiloxane.

Preferably, in step a), the chemical formula of the a, ω -dihydroxy polydimethylsiloxane is HO (Me)₂SiO)_mH, wherein m is 20 to E60, adding a solvent to the mixture; the feeding amount of the alpha, omega-dihydroxy polydimethylsiloxane is 40-400 kg/h;

the catalyst is selected from one of phosphazene, dodecyl benzene sulfonic acid and trifluoromethanesulfonic acid; the solvent in the catalyst solution is selected from ethyl acetate, dichloromethane or tetrachloroethane; the concentration of the catalyst solution is 5-20 g/L; the feeding amount of the catalyst solution is 0.02-0.2 kg/h;

the premixed raw materials also comprise a sealing head agent; the chemical formula of the end socket agent is Me (Me)₂SiO)_nMe or CH₂＝CH(Me₂SiO)_nCH＝CH₂Wherein n is 2-50; the feeding amount of the end sealing agent is 0.1-4 kg/h.

Preferably, in step B), the terminating agent is selected from one of diethylamine, tri-n-butylamine, trinonyl amine and silazane; the solvent in the terminator solution is selected from ethyl acetate, dichloromethane or tetrachloroethane; the mass solubility of the terminator solution is 5-20 g/L; the feeding amount of the terminator solution is 0.02-1 kg/h;

the vacuum degree of the polymerization reaction is 80-120 Pa;

the temperature of a screw barrel of the polymerization type double-screw extruder is 140-200 ℃, and the rotating speed of the screw is 90-150 rpm.

Preferably, in the step C), the temperature of the pre-devolatilization is 140-160 ℃, and the vacuum degree of the pre-devolatilization is 60-100 Pa.

Preferably, in the step D), the vacuum degree of the secondary enhanced devolatilization is 30-60 Pa;

the temperature of a cylinder body at the screw section of the devolatilization type screw extruder is 160-220 ℃, and the rotating speed of the screw is 110-170 rpm.

The invention provides a continuous production system of polysiloxane, which comprises: a premixer; a polymerization type double-screw extruder connected with the discharge port of the premixer; a first vacuum pumping system connected with an exhaust port of the polymerization type double-screw extruder; a static mixer connected with a discharge port of the polymerization type double-screw extruder; the falling strip type devolatilization device is connected with the discharge hole of the static mixer; the second vacuum pumping system is connected with the vacuum port of the falling strip devolatilizer; a devolatilization type double-screw extruder connected with a discharge port of the falling strip devolatilizer; and the third vacuum-pumping system is connected with a vacuum port of the devolatilization type double-screw extruder. In the invention, the end capping agent, the catalyst and the alpha, omega-dihydroxy polydimethylsiloxane are premixed in the premixer, and are subjected to polymerization reaction in the polymerization type double-screw extruder, so that the problem of difficult stirring of the ultrahigh molecular weight polysilane due to high viscosity is solved, the continuous production is facilitated, the rapid polymerization reaction can be completed within 5-8 min of residence time, the mixture after the polymerization reaction and the terminator solution terminate the polymerization reaction in the static mixer, the pre-devolatilization is performed in the falling strip devolatilizer, and the secondary intensive mixing of the screws is terminated, so that the problem that the ultrahigh viscosity polysiloxane is difficult to completely terminate is solved. Finally, the prepared polysiloxane has high viscosity and low volatile component.

Experimental results show that the viscosity of the polysiloxane prepared by the continuous production system of the polysiloxane is 300-8000 ten thousand cp, and the volatile content of the polysiloxane is not more than 0.13 wt%.

Drawings

FIG. 1 is a schematic flow chart of a system for continuously producing a polysiloxane according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an in-line two-phase mixer provided in accordance with one embodiment of the present invention;

FIG. 3 is a schematic structural view of a polymeric twin-screw extruder provided in one embodiment of the present invention;

FIG. 4 is a schematic diagram of the structure of a devolatilizing twin screw extruder provided in accordance with one embodiment of the present invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a continuous production system of polysiloxane, which comprises:

a premixer;

a polymerization type double-screw extruder connected with the discharge port of the premixer;

a first vacuum pumping system connected with an exhaust port of the polymerization type double-screw extruder;

a static mixer connected with a discharge port of the polymerization type double-screw extruder;

the falling strip type devolatilization device is connected with the discharge hole of the static mixer;

the second vacuum pumping system is connected with the vacuum port of the falling strip devolatilizer;

a devolatilization type double-screw extruder connected with a discharge port of the falling strip devolatilizer;

and the third vacuum-pumping system is connected with a vacuum port of the devolatilization type double-screw extruder.

See fig. 1. FIG. 1 is a schematic flow chart of a system for continuously producing a polysiloxane according to an embodiment of the present invention.

The continuous production system of the polysiloxane comprises a premixer. In certain embodiments of the present invention, the premixer is an in-line two-phase mixer.

In certain embodiments of the present invention, the in-line two-phase mixer comprises:

the cylinder comprises an upper chamber and a lower chamber;

a stirring shaft penetrating through the upper chamber and extending to the lower chamber;

the double-layer frame blade paddles are arranged on the stirring shaft, the upper frame blade paddle of the double-layer frame blade paddles rotates around the stirring shaft in the upper cavity, and the lower frame blade paddle of the double-layer frame blade paddles rotates around the stirring shaft in the lower cavity; the blades of the double-layer frame blade paddle are provided with flow guide holes; a motor connected with a stirring shaft extending out of the upper cavity;

a siloxane feeding port is arranged on the side surface of the lower chamber;

the bottom of the lower chamber is provided with a head sealing agent feed opening and a catalyst feed opening;

and a discharge hole is formed in the side surface of the upper cavity.

See fig. 2. Fig. 2 is a schematic structural diagram of an in-line two-phase mixer according to an embodiment of the present invention.

In certain embodiments of the invention, the upper chamber and the lower chamber are opposed. In some embodiments of the invention, the upper and lower chambers are equal in volume. In some embodiments of the present invention, the volume of the cylinder is 2-15L. In certain embodiments, the volume of the barrel is 5L. In some embodiments of the present invention, the height of the cylinder is 0.3 to 0.5 m. In certain embodiments, the height of the barrel is 0.3 m.

In some embodiments of the invention, the blade diameter of the double-layer frame blade is 0.08-0.18 m. In certain embodiments, the blade diameter of the double layer frame blade paddle is 0.13 m.

In some embodiments of the invention, the length of the upper frame blade along the direction of the stirring shaft is 0.13-0.23 m. In some embodiments, the length of the upper frame blade in the direction of the stirring shaft is 0.13 m. In some embodiments of the invention, the length of the lower frame blade in the direction of the stirring shaft is 0.13-0.23 m. In some embodiments, the length of the lower frame blade in the direction of the stirring shaft is 0.13 m.

In some embodiments of the present invention, the rotation speed of the stirring shaft is 100 to 500 rpm. In certain embodiments, the stirring shaft has a rotational speed of 150rpm or 500 rpm.

The invention has no special limitation on the arrangement mode of the diversion holes on the blades, and the diversion holes can be linearly arranged along the direction parallel to the stirring shaft.

In some embodiments of the present invention, the diameter of the flow guiding hole is 5-10 mm. In some embodiments, the diameter of the flow guide hole is 5 mm. The effect of water conservancy diversion hole is to improve stirring effect, reduces the energy consumption, the energy saving.

In some embodiments of the invention, the number of the flow guide holes on the blade of the upper frame blade is 2-4. In some embodiments, the number of the flow guide holes on the blade of the upper frame blade is 3. In some embodiments of the invention, the number of the flow guide holes on the blade of the lower frame blade is 2-4. In some embodiments, the number of the flow guide holes on the blade of the lower frame blade is 3.

In some embodiments of the present invention, the capping agent is introduced from a capping agent feed port of the lower chamber, the catalyst is introduced from a catalyst feed port of the lower chamber, the α, ω -dihydroxypolydimethylsiloxane is introduced from a siloxane feed port of the lower chamber, the preliminary mixing is performed in the lower chamber, the further mixing is performed in the upper chamber, and then the capping agent is discharged from a discharge port of the upper chamber.

The continuous production system of the polysiloxane also comprises a polymerization type double-screw extruder. In an embodiment of the present invention, the polymerization type twin-screw extruder is provided with a feed port, a discharge port and a vent port. And a feed inlet of the polymerization type double-screw extruder is connected with a discharge outlet of the premixer. In certain embodiments of the present invention, the polymeric twin screw extruder is a corotating twin screw extruder. In certain embodiments of the present invention, the polymeric twin screw extruder is fed in the following manner: feeding from the barrel at the tail part of the screw and discharging from the barrel at the root part of the screw. The barrel at the tail part of the screw is a closed barrel, so that a local high vacuum environment can be established, and the sealing property of the screw is improved.

In certain embodiments of the present invention, the polymeric twin screw extruder comprises:

a twin screw extruder body; a feed inlet is arranged at the barrel at the tail part of the screw rod, and a discharge outlet is arranged at the barrel at the root part of the screw rod;

a devolatilization chamber arranged on the barrel body of the screw extruder body.

See fig. 3. FIG. 3 is a schematic structural view of a polymerization type twin-screw extruder provided in one embodiment of the present invention.

The structure of the twin-screw extruder body is not particularly limited in the present invention, and may be a combination of a screw and a barrel well known to those skilled in the art.

In certain embodiments of the present invention, the diameter of the screw of the twin-screw extruder body is 50 to 100mm, and the length-diameter ratio of the screw is 60 to 80: 1. specifically, the diameter of a screw of the double-screw extruder body is 75mm, and the length-diameter ratio of the screw is 80: 1.

when the double-screw extruder works, the premix discharged from the discharge port of the premixer enters the double-screw extruder body from the feed port of the double-screw extruder body to carry out polymerization reaction, and the reactant after the polymerization reaction is discharged from the discharge port.

The polymeric twin screw extruder further comprises a devolatilization chamber. The devolatilization chamber is arranged on the cylinder body of the double-screw extruder body. When the reactant pushed forward passes through the cylinder section provided with the devolatilization chamber, devolatilization is carried out under the vacuum condition, and the volatile matter is discharged through an exhaust port of the devolatilization chamber.

In some embodiments of the present invention, the devolatilization chamber is a cuboid, the length of the cuboid is 2 to 8 times the diameter of the screw, the width of the cuboid is 2 to 4 times the diameter of the screw, and the height of the cuboid is 4 to 8 times the diameter of the screw. In certain embodiments, the devolatilization chamber is a cuboid having a length that is 8 times the diameter of the screw, a width that is 4 times the diameter of the screw, and a height that is 8 times the diameter of the screw.

In some embodiments of the present invention, the number of devolatilization chambers is 3 to 5. In certain embodiments, the number of devolatilization chambers is 4 or 5. When there are a plurality of devolatilization chambers, the present invention is not particularly limited to the interval between the devolatilization chambers in the barrel, and it is preferable that the intervals between the devolatilization chambers are the same.

In some embodiments of the present invention, the diameter of the devolatilization chamber exhaust port is 100 to 200 nm.

And discharging the devolatilized reactant through a discharge port of a polymerization type double-screw extruder, and discharging the volatile component from a gas outlet of the devolatilization chamber.

The continuous production system of the polysiloxane also comprises a first vacuum-pumping system. The first vacuum-pumping system is connected with an exhaust port of the polymerization type double-screw extruder and provides a vacuum environment for polymerization reaction in the polymerization type double-screw extruder. In certain embodiments of the present invention, the first evacuation system is a first vacuum pump. The first vacuum pump is not particularly limited, and any vacuum pump known to those skilled in the art may be used.

The continuous production system of the polysiloxane also comprises a static mixer. The static mixer is connected with a discharge port of the polymerization type double-screw extruder. And terminating the polymerization reaction of the mixture after the polymerization reaction and the terminating agent solution in a static mixer to obtain the crude product of the ultrahigh-viscosity polysiloxane. In certain embodiments of the invention, the static mixer is provided with a feed inlet, a terminator inlet and a discharge outlet. And the feed inlet of the static mixer is connected with the discharge outlet of the polymerization type double-screw extruder.

In certain embodiments of the invention, the static mixer comprises one or more of a SMK type static mixer, a SMX type static mixer, a SMH type static mixer, and a SML type static mixer. In certain embodiments of the invention, the static mixers include SMX-type static mixers and SMH-type static mixers.

In certain embodiments of the invention, the static mixer is a static mixer of the SMX type manufactured by Sulzer, comprising 2 or 3 segments of 35mm or 50mm diameter and 300mm length; 3 sections with the diameter of 50mm or 80mm and the length of 500mm are connected in series from small to large.

The continuous production system of the polysiloxane also comprises a falling strip devolatilizer. The falling strip type devolatilization device is connected with a discharge hole of the static mixer. The falling strip type devolatilization device is provided with a feed inlet, a discharge outlet and a devolatilization port. And the feed inlet of the falling strip devolatilizer is connected with the discharge outlet of the static mixer. And feeding the ultra-high viscosity polysiloxane crude product discharged from the static mixer into a falling strip devolatilizer through a feed inlet of the falling strip devolatilizer, pre-devolatilizing in the falling strip devolatilizer under a vacuum condition, discharging the pre-devolatilized ultra-high viscosity polysiloxane crude product through a discharge outlet of the falling strip devolatilizer, and discharging the volatile component through a devolatilization port of the falling strip devolatilizer.

In certain embodiments of the present invention, the drop bar devolatilizer is a drop bar devolatilizer. The structure of the falling-strip devolatilizer of the present invention is not particularly limited, and a falling-strip devolatilizer known to those skilled in the art may be used. In certain embodiments of the present invention, the source of the falling strip devolatilizer is generally commercially available. In certain embodiments of the present invention, the falling strand devolatilizer comprises a feed port, a discharge port, and a vacuum port.

In some embodiments of the present invention, the devolatilization chamber of the falling strand devolatilizer has a height of 1400mm, a diameter of 1200mm, a pore size (diameter) of the perforated plate of 3mm, and 1 vacuum pumping port.

The continuous production system of the polysiloxane also comprises a second vacuum-pumping system. And the second vacuum pumping system is connected with the vacuum port of the falling strip devolatilizer and provides a vacuum environment for pre-devolatilization of the falling strip devolatilizer. In certain embodiments of the present invention, the second evacuation system is a second vacuum pump. The second vacuum pump is not particularly limited in the present invention, and any vacuum pump known to those skilled in the art may be used.

The continuous production system of the polysiloxane also comprises a devolatilization type double-screw extruder. In an embodiment of the present invention, the devolatilization twin screw extruder is provided with a feed port, a discharge port, and a vent port. And the feed inlet of the devolatilization type double-screw extruder is connected with the discharge outlet of the falling strip devolatilizer. In certain embodiments of the present invention, the devolatilizing twin screw extruder is a corotating twin screw extruder. In certain embodiments of the present invention, the devolatilizing twin screw extruder is fed in the following manner: feeding from the barrel at the tail part of the screw and discharging from the barrel at the root part of the screw. The barrel at the tail part of the screw is a closed barrel, so that a local high vacuum environment can be established, and the sealing property of the screw is improved.

In certain embodiments of the present invention, the devolatilizing twin screw extruder comprises:

a twin screw extruder body; a feed inlet is arranged at the barrel at the tail part of the screw rod, and a discharge outlet is arranged at the barrel at the root part of the screw rod;

a devolatilization chamber arranged on the barrel body of the screw extruder body.

See fig. 4. FIG. 4 is a schematic diagram of the structure of a devolatilizing twin screw extruder provided in accordance with one embodiment of the present invention.

The structure of the twin-screw extruder body is not particularly limited in the present invention, and may be a combination of a screw and a barrel well known to those skilled in the art.

In certain embodiments of the present invention, the diameter of the screw of the twin-screw extruder body is 60 to 120mm, and the length-diameter ratio of the screw is 40 to 60: 1. specifically, the diameter of the screw of the double-screw extruder body is 80mm, and the length-diameter ratio of the screw is 60: 1 or 40: 1.

when the device works, the ultrahigh-viscosity polysiloxane discharged from the discharge hole of the falling bar type devolatilizer enters the double-screw extruder body from the feed hole of the double-screw extruder body to be subjected to secondary enhanced devolatilization, and the ultrahigh-viscosity polysiloxane subjected to enhanced devolatilization is discharged from the discharge hole.

The devolatilization twin screw extruder also includes a devolatilization chamber. The devolatilization chamber is arranged on the cylinder body of the double-screw extruder body. When the ultra-high viscosity polysiloxane pushed forward passes through a cylinder section provided with a devolatilization chamber, the enhanced devolatilization is carried out under the vacuum condition, and volatile components are discharged through an exhaust port of the devolatilization chamber.

In some embodiments of the present invention, the devolatilization chamber is a cuboid, the length of the cuboid is 2 to 8 times the diameter of the screw, the width of the cuboid is 2 to 4 times the diameter of the screw, and the height of the cuboid is 4 to 8 times the diameter of the screw. In certain embodiments, the devolatilization chamber is a cuboid having a length that is 8 times the diameter of the screw, a width that is 4 times the diameter of the screw, and a height that is 8 times the diameter of the screw.

In some embodiments of the present invention, the number of devolatilization chambers is 2 to 4. In certain embodiments, the number of devolatilization chambers is 3 or 4. When there are a plurality of devolatilization chambers, the present invention is not particularly limited to the interval between the devolatilization chambers in the barrel, and it is preferable that the intervals between the devolatilization chambers are the same.

And discharging the devolatilized ultrahigh-viscosity polysiloxane through a discharge port of a devolatilization type double-screw extruder, and discharging volatile components from an exhaust port of the devolatilization chamber.

The continuous production system of the polysiloxane further comprises a third vacuum-pumping system. And the third vacuum pumping system is connected with a vacuum port of the devolatilization type double-screw extruder and provides a vacuum environment for secondary strengthening devolatilization in the devolatilization type double-screw extruder. In certain embodiments of the present invention, the third vacuum pumping system is a third vacuum pump. The third vacuum pump is not particularly limited in the present invention, and any vacuum pump known to those skilled in the art may be used.

In certain embodiments of the present invention, the continuous production system for polysiloxane further comprises a cooling device and a filtering device. And a feed inlet of the cooling device is connected with a discharge outlet of the devolatilization type double-screw extruder. And the feed inlet of the filtering device is connected with the discharge outlet of the cooling device. Please supplement the filtering effect. In certain embodiments of the invention, the cooling device is a generally conventional heat exchanger. In certain embodiments of the invention, the filtration device is a conventional stainless steel filter.

The invention also provides a method for continuously producing polysiloxane by adopting the continuous production system of polysiloxane, which comprises the following steps:

A) premixing alpha, omega-dihydroxy polydimethylsiloxane and a catalyst solution to obtain a premix;

B) carrying out polymerization reaction on the premix in a polymerization type double-screw extruder, and terminating the polymerization reaction of the mixture after the polymerization reaction and a terminator solution in a static mixer to obtain an ultra-high viscosity polysiloxane crude product;

C) pre-devolatilizing the ultra-high viscosity polysiloxane crude product in a falling strip devolatilizer;

D) and carrying out secondary enhanced devolatilization on the pre-devolatilized ultrahigh-viscosity polysiloxane in a devolatilization type screw extruder to obtain polysiloxane.

In certain embodiments of the invention, the alpha, omega-dihydroxy polydimethylsiloxane has the formula HO (Me)₂SiO)_mH, wherein m is 20-60. In some embodiments, m is 25 to 45. In certain embodiments of the present invention, the alpha, omega-dihydroxy polydimethylsiloxane may be fed at a rate of 40 to 400 kg/h. In certain embodiments, the feed rate of the alpha, omega-dihydroxy polydimethylsiloxane is 100 kg/h.

In certain embodiments of the present invention, the catalyst is selected from one of phosphazenes, dodecylbenzene sulfonic acid, and trifluoromethanesulfonic acid. In certain embodiments of the invention, the solvent in the catalyst solution is selected from ethyl acetate, dichloromethane or tetrachloroethane. In certain embodiments of the present invention, the concentration of the catalyst solution is 5 to 20 g/L. In certain embodiments, the concentration of the catalyst solution is 5 g/L. In certain embodiments of the invention, the catalyst solution is fed in an amount of 0.02 to 0.2 kg/h. In certain embodiments, the catalyst solution is fed in an amount of 0.06 kg/h.

In certain embodiments of the present invention, the premixed feed further comprises a capping agent.

In certain embodiments of the invention, the capping agent has the formula Me (Me)₂SiO)_nMe or CH₂＝CH(Me₂SiO)_nCH＝CH₂Wherein n is 2 to 50. In some embodiments, n is 20 to 40. In certain embodiments of the invention, the feeding amount of the capping agent is 0.1-4 kg/h. In certain embodiments, the capping agent is fed at 0.273 kg/hr, 0.241 kg/hr, 0.203 kg/hr, or 0.183 kg/hr.

In the present invention, the premixing is carried out in a premixer.

In some embodiments of the present invention, the stirring rate of the premixing is 100 to 500 rpm. In certain embodiments, the agitation rate of the pre-mixing is 150rpm, 500rpm, or 200 rpm.

And after obtaining the pre-mixture, carrying out polymerization reaction on the pre-mixture in a polymerization type double-screw extruder, and terminating the polymerization reaction of the mixture after the polymerization reaction and a terminator solution in a static mixer to obtain the ultra-high viscosity polysiloxane crude product.

In certain embodiments of the present invention, the polymeric twin-screw extruder has a screw barrel temperature of 140 to 200 ℃. In certain embodiments, the polymeric twin-screw extruder has a screw barrel temperature of 160 ℃ to 180 ℃ or 190 ℃. In certain embodiments of the present invention, the polymeric twin-screw extruder has a screw speed of 90 to 150 rpm. In certain embodiments, the polymeric twin screw extruder has a screw speed of 100 to 140rpm, 120rpm, or 100 rpm.

In some embodiments of the present invention, the degree of vacuum of the polymerization reaction is 80 to 120 Pa. In some embodiments, the vacuum degree of the polymerization reaction is 80-100 Pa.

In certain embodiments of the present invention, the terminating agent is selected from one of diethylamine, tri-n-butylamine, trinonyl amine, and silazane. In certain embodiments of the present invention, the solvent in the terminator solution is selected from ethyl acetate, dichloromethane, or tetrachloroethane. In some embodiments of the invention, the mass solubility of the terminator solution is 5-20 g/L. In certain embodiments, the terminator solution has a mass solubility of 5-10 g/L or 10 g/L. In certain embodiments of the invention, the amount of the terminator solution fed is 0.02 to 1kg/h or 0.06 kg/h.

After the ultrahigh-viscosity polysiloxane crude product is obtained, pre-devolatilizing the ultrahigh-viscosity polysiloxane crude product in a falling strip devolatilizer.

In some embodiments of the present invention, the temperature of the pre-devolatilization is 140 to 160 ℃. In certain embodiments, the temperature of the pre-devolatilization is 180 ℃. The vacuum degree of the pre-devolatilization is 60-100 Pa. In some embodiments, the vacuum degree of the pre-devolatilization is 60-80 Pa.

After pre-devolatilization, carrying out secondary enhanced devolatilization on the pre-devolatilized ultrahigh-viscosity polysiloxane in a devolatilization type screw extruder to obtain polysiloxane.

In certain embodiments of the present invention, the barrel temperature of the screw section of the devolatilizing screw extruder is 160 to 220 ℃. In certain embodiments, the barrel temperature of the screw section of the devolatilizing screw extruder is 160-180 ℃, 190 ℃ or 200 ℃. In certain embodiments of the present invention, the devolatilization screw extruder has a screw speed of 110 to 170 rpm. In certain embodiments, the devolatilization screw extruder has a screw speed of 110 to 140rpm, 100rpm, or 120 rpm.

In some embodiments of the present invention, the vacuum degree of the secondary enhanced devolatilization is 30 to 60 Pa. In some embodiments, the vacuum degree of the secondary enhanced devolatilization is 30-50 Pa.

In some embodiments of the present invention, cooling and filtering are further included after the secondary enhanced devolatilization. The cooling and filtering method of the present invention is not particularly limited, and a cooling and filtering method known to those skilled in the art may be used.

The source of the above-mentioned raw materials is not particularly limited in the present invention, and may be generally commercially available.

Alpha, omega-dihydroxy polydimethylsiloxane, a catalyst and an end sealing agent are metered and conveyed into a mixer for premixing, the mixture is uniformly mixed and then continuously input into a double-screw extruder for polymerization, by-product water is discharged from an exhaust chamber, the obtained crude product of the non-terminated ultra-high viscosity polysiloxane is continuously input into a static mixer for combination and termination, the obtained terminated ultra-high viscosity polysiloxane crude product is continuously input into a falling bar devolatilizer for pre-devolatilization, low molecules are discharged from a vacuum-pumping port of the devolatilizer, the obtained pre-low ultra-high viscosity polysiloxane is continuously input into a devolatilization type double screw for secondary strengthening devolatilization, meanwhile, the pre-low ultra-high viscosity polysiloxane is secondarily heated in the devolatilization type screw extruder, the heat loss in the falling bar devolatilizer can be compensated, the interface update difference in the later stage of the devolatilization is strengthened, low molecules coated inside are released, and the low molecules are discharged from the exhaust chamber, cooling and filtering to obtain the polysiloxane with ultrahigh viscosity and ultralow volatile matter.

The technical advantages of the invention are as follows:

(1) the invention adopts the double-screw extruder as the polymerization reactor, overcomes the problem of difficult stirring of the ultrahigh molecular weight polysilane due to high viscosity, is beneficial to continuous production, and can complete rapid polymerization reaction within 5-8 min of residence time.

(2) In the invention, the double-screw extruder has excellent mixing effect, the reaction termination residence time of the static mixer can be freely regulated and controlled, and the problem that the ultrahigh-viscosity polysiloxane is difficult to completely terminate is solved by primary termination of the static mixer and secondary enhanced mixing termination of the screw.

(3) The invention adopts a strip falling devolatilizer for primary devolatilization and a double-screw secondary reinforced devolatilization process to solve the problem that the ultra-high viscosity polysiloxane is difficult to be deeply devolatilized, and the volatile matter can be reduced to below 0.2 wt%.

(4) The polymerization and devolatilization type screw adopts a screw original piece as a reverse conveying original piece, the feeding mode is feeding from the barrel at the tail part of the screw, and discharging from the barrel at the root part of the screw, so that the tightness of the screw can be further obviously improved, the high vacuum degree of polymerization reaction and devolatilization can be established, and the synthesis of polysiloxane with ultrahigh viscosity and ultralow volatility is facilitated.

Experimental results show that the viscosity of the polysiloxane prepared by the continuous production system of the polysiloxane is 300-8000 ten thousand cp, and the volatile content of the polysiloxane is not more than 0.13 wt%.

In order to further illustrate the present invention, the following examples are provided to describe the continuous production system and the production method of a polysiloxane of the present invention in detail, but they should not be construed as limiting the scope of the present invention.