A polysiloxane production system

Abstract

This invention relates to a polysiloxane production system. The polysiloxane production system includes a metering pump, a prepolymer reactor, a first gear pump, a first biaxial stirrer, a twin-screw extruder, a second biaxial stirrer, and a second gear pump, connected sequentially by pipelines; the twin-screw extruder is equipped with a vacuum system; the first and second biaxial stirrers are the biaxial stirrers themselves. Based on the characteristics of material viscosity and volatile matter content during the preparation process, and through the control of polymerization and de-oxidation conditions using the biaxial stirrers, ultra-high viscosity, ultra-low volatile matter polysiloxanes are prepared within the optimal operating range of the equipment.

Description

Technical Field

[0001] This invention relates to the field of polysiloxane production, and in particular to a polysiloxane production system. Background Technology

[0002] Industrial production of polysiloxanes commonly employs a mixed siloxane equilibrium method, using raw materials such as DMC (dimethylcyclosiloxane) or D4 (octamethylcyclotetrasiloxane) as raw materials, followed by ring-opening polymerization after dehydration. Unlike the preparation of other polymers, due to the chemical equilibrium of the polymerization reaction, some cyclosiloxanes are always not converted into polysiloxanes, with polymerization yields generally around 80-85%. Therefore, the residual cyclosiloxanes (low molecular weight) must be removed. Furthermore, trace amounts of residual low molecular weight polysiloxanes can, to some extent, affect their use in high-end fields such as electronics, optics, and cosmetics. For example, the EU REACH regulation stipulates that D4 and D5 in cosmetics must be less than 1000 ppm; and even in some electronics fields, the limit for D3-D10 is around 100 ppm.

[0003] Currently, the main production methods for ultra-high viscosity polysiloxanes include polymerization reactors, and the de-volatilization methods employed include strip devolatilization and direct de-volatilization within the reactor. These methods have two main problems: first, ordinary paddle-type stirred tanks are unsuitable for mixing and discharging ultra-high viscosity polysiloxanes during polymerization; second, strip devolatilization cannot meet the requirements for preparing ultra-low volatile ultra-high viscosity polysiloxanes, as the volatile content is generally around 5000-15000 ppm, making it difficult to reduce the volatile content to trace levels (D3-D10 < 100 ppm).

[0004] Chinese patent application No. 200910193006.1 discloses a reactor with an S-type stirrer, which uses dimethylcyclosiloxane or α,ω-dihydroxypolydimethylsiloxane as raw materials to intermittently prepare ultra-high molecular weight polysiloxane, while generating a high amount of volatile matter.

[0005] Chinese invention patent application number 201520828078.2 discloses a polymerization reactor polymerization process, static mixer desaturation, screw extrusion secondary desaturation, and reaction production to prepare ultra-high molecular weight polysiloxane with a volatile content of up to 6000 ppm.

[0006] Chinese invention patent application No. 201721186548.5 discloses a reactor with an S-shaped powerful stirring device for preparing ultra-high molecular weight polysiloxane.

[0007] Chinese invention patent CN111574714A discloses a method for preparing ultra-low volatile and ultra-high viscosity polysiloxane using α,ω-dihydroxy polydimethylsiloxane as raw material and a twin-screw extruder as a reactor, through flash evaporation and secondary de-degradation in a twin-screw extruder. However, this method is limited to raw materials, only α,ω-dihydroxy polydimethylsiloxane can be used, and the residence time of the secondary de-degradation in the twin-screw extruder is short, so the volatile content cannot reach the requirement of <100ppm.

[0008] In summary, existing technologies for preparing ultra-high viscosity polysiloxanes suffer from low production efficiency, poor product quality, difficulty in process control, high production costs, and product quality that fails to meet the requirements of high-end applications due to improper equipment selection and process control. Therefore, there is an urgent need to find a new production method for synthesizing ultra-high viscosity polysiloxanes. This method must not only meet the product's characteristics for continuous production but also ensure stable production, improve product quality, and successfully achieve industrial-scale production. Summary of the Invention

[0009] This patent addresses the shortcomings of existing technologies by developing a polysiloxane production system. This method is simple to operate, energy-efficient, and highly effective, reducing volatile matter to trace levels. The core of this invention lies in utilizing the characteristics of material viscosity and volatile matter content during the preparation process. Through a biaxial stirrer and control of polymerization and devolatile matter conditions, ultra-high viscosity, ultra-low volatile matter polysiloxanes are prepared within the optimal operating range of the equipment.

[0010] A polysiloxane production system includes a prepolymer reactor, a first gear pump, a first twin-screw agitator, a twin-screw extruder, a second twin-screw agitator, and a second gear pump connected sequentially by pipelines; the prepolymer reactor is also connected to several metering pumps for feeding; the twin-screw extruder is equipped with a vacuum system; the first and second twin-screw agitators are twin-screw agitators;

[0011] The first and second biaxial agitators each include two parallel agitator shafts arranged within a cylindrical body. Each shaft has several agitators, including a mixing disc and a stirring rod. The mixing disc is fixed to the first and second shafts. The stirring rod includes a stirring beam and a first and a second vertical rod fixed to both ends of the beam. The first and second vertical rods are perpendicular to the beam. The beam is vertically mounted on the outer circumference of the mixing disc and fits against the cylindrical body, such that the first and second vertical rods are located on opposite sides of the mixing disc. The first and second vertical rods are perpendicular to and point towards either the first or second agitator shaft. An end cap is provided at the end of the cylindrical body. The first and second shafts extend outside the cylindrical body through a sealing component and are connected to a power mechanism.

[0012] Along the direction of the first stirring shaft and the second stirring shaft, the second vertical rod on the first stirring shaft is located between the stirring plate on the second stirring shaft and the first vertical rod, so that when the first stirring shaft and the second stirring shaft are rotated, the second vertical rod on the first stirring shaft engages with the first vertical rod on the second stirring shaft.

[0013] The cylinder has a material inlet on one side and a discharge screw on the other side; the discharge screw has a terminator inlet in the middle and a material outlet.

[0014] Furthermore, the cylinder is divided into three sections: A, B, and C, and the cross-sectional area of ​​the stirring rod decreases sequentially from section A to section B to section C.

[0015] Furthermore, the gap between the stirring plate and the cylinder increases sequentially from section A to section B to section C, and the gap between the stirring plate and the cylinder in section A is <4mm.

[0016] Furthermore, a jacket or heat tracing pipe is provided on the outside of the dual-shaft agitator to compensate for latent heat dissipation.

[0017] Furthermore, the cylinder also has a heating medium inlet and a heating medium outlet, and the first and second stirring shafts are hollow structures, so that the heating medium is introduced into the hollow structure. The heating medium is saturated water vapor or heat transfer oil.

[0018] Furthermore, the biaxial stirrer has an opening on its upper side, which connects to a devolatilization chamber. The number of devolatilization chambers is 1 to 3, and each devolatilization chamber is connected to a vacuum system.

[0019] Furthermore, the terminator inlet is one or both of a liquid atomizing nozzle and a gas pressurizing device.

[0020] Furthermore, the number of metering pumps is three.

[0021] Furthermore, the twin-screw extruder includes two counter-rotating, meshing screws, and an extruder barrel composed of several second and third barrels.

[0022] Furthermore, the extruder barrel is composed of nine sections of second and third barrels, specifically, a second barrel, a second barrel, a third barrel, a second barrel, a second barrel, a third barrel, a second barrel, a third barrel, and a second barrel connected in sequence; the first section of the second barrel has a twin-screw extruder feed inlet; the third section of the third barrel has a gas feed inlet; the sixth and eighth sections of the third barrel have devolatilization outlets; and the ninth section of the second barrel has a material outlet. The first section of the second cylinder has a material inlet. The second cylinder in the first section is equipped with 32 / 32 and 48 / 48 combination screw components for material conveying. The second cylinder in the second section is equipped with a ZME12 / 24 screw component for strong mixing of the terminator and materials. The third cylinder in the third section has a gas inlet, a large-opening gas inlet, and is equipped with 32 / 32, 48 / 48, and 64 / 64 combination screw components. The fourth and fifth sections of the second cylinder are enclosed cylinders, containing ZME12 / 24, K90° / 5 / 48, and K60° / 4 / 32 combination screw components for secondary mixing of the terminator and materials. The sixth section of the third cylinder has a large-opening gas inlet. The first section has a devolatilization port 3-3-1. The third cylinder in the sixth section is equipped with 32 / 32, 48 / 48, and 64 / 64 combined screw components. The second cylinder in the seventh section is a closed cylinder, equipped with K90° / 5 / 48 and K60° / 4 / 32 combined screw components. The third cylinder in the eighth section has a large-opening devolatilization port 3-3-2, equipped with 32 / 32, 48 / 48, and 64 / 64 combined screw components. The second cylinder in the ninth section is a closed cylinder, equipped with 32 / 32 and 48 / 48 combined screw components, serving as a material conveying area. A material outlet is located at the tail end. Each heating cylinder is equipped with an electric heating module, which can be set to a reaction temperature of 30-300℃.

[0023] Furthermore, the twin-screw extruder has a length-to-diameter ratio of 20 to 50:1; a groove depth ratio (inner-to-outer diameter ratio) of 1.8; and a screw diameter of 50 to 100 mm. The feeding method is to feed from the tail of the screw and discharge from the root of the screw. The twin-screw extruder is equipped with 1-2 stopper ports for adding a stopper agent, and the neutralization length at each stop is 10-20 times the screw length.

[0024] The molecular structure of the ultra-high viscosity, ultra-low volatile polysiloxane is: X(MeRSiO). m (Me2SiO) n Me2SiX, where X is one of methyl, vinyl, or hydroxyl, R is one or two of methyl, phenyl, ethyl, trifluoropropyl, or vinyl, m+n≥5000, m≥0, and n≥0.

[0025] The siloxane is one of cyclosiloxane or α,ω-dihydroxypolysiloxane.

[0026] The sealing agent is X(Me2SiO). n Me2SiX, where X is one of methyl or vinyl, 10 <n<20。

[0027] The cyclosiloxane raw material is methylcyclosiloxane (Me2SiO). x methylvinylcyclosiloxane (MeViSiO) x Trifluoropropylmethylcyclotrisiloxane (C2H4CF3MeSiO) x phenylcyclosiloxane (Ph2ViSiO) x Methylphenylcyclosiloxane (MePhSiO) x One or more of the alkanes, where x is 3-6.

[0028] The α,ω-dihydroxy polysiloxane raw material is α,ω-dihydroxy polydimethylsiloxane HO (MeRSiO). y (Me2SiO) z H,α,ω-dihydroxypolymethylvinylsiloxane HO (MeViSiO) y (Me2SiO) z H,α,ω-dihydroxypolymethyltrifluoropropylsiloxane HO(C2H4CF3MeSiO) y (Me2SiO) z H,α,ω-dihydroxypolymethylphenylsiloxane HO(MePhSiO) y (Me2SiO) z H,α,ω-dihydroxypolydiphenylsiloxane HO(Ph₂SiO) y (Me2SiO) z One or more of H, of which 10 <y+z<20,y≥0,Z≥0。

[0029] The raw material is a cyclosiloxane, wherein the water content of the cyclosiloxane is 10-80 ppm, more preferably 10-50 ppm, and even more preferably 10-20 ppm.

[0030] Using cyclosiloxane as a raw material, the catalyst is one of potassium siloxaneol, sodium siloxaneol, and cesium siloxaneol, preferably potassium siloxaneol; the catalyst addition amount is 10-50 ppm, more preferably 10-30 ppm, and even more preferably 10-20 ppm. The diluent is cyclosiloxane, with a mass solubility controlled at 10-100 g / L, more preferably 10-50 g / L, and even more preferably 10-20 g / L.

[0031] Using cyclosiloxane as raw material, the prepolymerization reaction temperature is 80-140℃, more preferably 90-140℃, and even more particularly preferably 100-130℃.

[0032] Using cyclosiloxane as raw material, the average residence time of the prepolymerization reaction is 0.5-2h, more preferably 0.5-1.5h, and even more preferably 0.5-1h.

[0033] Using cyclosiloxane as raw material, the stirring rate of the prepolymerization reaction is 20-100 rpm, more preferably 20-80 rpm, and even more particularly preferably 20-60 rpm.

[0034] Using cyclosiloxane as raw material, the polymerization reaction temperature is 140-180℃, more preferably 150-180℃, and even more particularly preferably 160-170℃.

[0035] Using cyclosiloxane as raw material, the average residence time of the polymerization is preferably 2-5 hours, more preferably 3-5 hours, and even more particularly preferably 3-4 hours.

[0036] Using cyclosiloxane as a raw material, the terminator is one or more terminators such as silanized phosphate ester and phosphoric acid. The addition amount is 10-50 ppm, more preferably 10-30 ppm, and even more preferably 10-20 ppm. The diluent for the terminator is cyclosiloxane, with a mass solubility controlled at 10-100 g / L, more preferably 10-50 g / L, and even more preferably 10-20 g / L.

[0037] Using cyclosiloxane as raw material, the pre-degradation temperature is preferably 160-220℃, more preferably 160-210℃, and even more preferably 170-210℃.

[0038] Using cyclosiloxane as raw material, the pre-depressurization absolute pressure is preferably 100-500 Pa, more preferably 100-300 Pa, and even more particularly preferably 200-300 Pa.

[0039] Using cyclosiloxane as raw material, the de-lowering temperature is preferably 160-230℃, more preferably 170-220℃, and even more preferably 180-210℃.

[0040] Using cyclosiloxane as raw material, the absolute pressure of the de-depletion is preferably 20-80 Pa, more preferably 20-60 Pa, and even more particularly preferably 20-30 Pa.

[0041] Using cyclosiloxane as raw material, the desliming time is preferably 0.5-2h, more preferably 1-2h, and particularly preferably 1.5-2h.

[0042] Using α,ω-dihydroxypolysiloxane as a raw material, the catalyst is a phosphazene chloride catalyst, added at an amount of 2-20 ppm, more preferably 2-10 ppm, and even more preferably 2-5 ppm. The catalyst diluent is one or more of ethyl acetate, methyl acetate, ethyl formate, toluene, benzene, and xylene, with a mass solubility controlled at 10-100 g / L, more preferably 10-50 g / L, and even more preferably 10-20 g / L.

[0043] Using α,ω-dihydroxypolysiloxane as raw material, the prepolymerization reaction temperature is 0-50℃, more preferably 20-40℃, and even more particularly preferably 20-30℃.

[0044] Using α,ω-dihydroxypolysiloxane as raw material, the prepolymerization reaction time is 0.5-2h, more preferably 0.5-1.5h, and even more preferably 0.5-1h.

[0045] Using α,ω-dihydroxypolysiloxane as raw material, the stirring rate of the prepolymerization reaction is 20-100 rpm, more preferably 20-80 rpm, and even more particularly preferably 20-60 rpm.

[0046] Using α,ω-dihydroxypolysiloxane as raw material, the polymerization temperature is 80-180℃, more preferably 100-160℃, and even more particularly preferably 120-160℃.

[0047] Using α,ω-dihydroxypolysiloxane as raw material, the absolute pressure of the polymerization is preferably 20-100 Pa, more preferably 20-80 Pa, and even more preferably 20-60 Pa.

[0048] Using α,ω-dihydroxypolysiloxane as raw material, the polymerization time is preferably 10-120 min, more preferably 10-80 min, and even more preferably 10-40 min.

[0049] The terminator is one or more of diethylamine, triethylamine, tri-n-butylamine, hexamethyldisilazane, and cyclotrisilazane. The amount of the terminator added is 3-30 ppm, more preferably 3-15 ppm, and even more preferably 3-7 ppm. The catalyst diluent is one or more of ethyl acetate, cyclosiloxane, toluene, benzene, and xylene, with a mass solubility controlled at 10-100 g / L, more preferably 10-50 g / L, and even more preferably 10-20 g / L.

[0050] Using α,ω-dihydroxypolysiloxane as raw material, the pre-degradation temperature is preferably 160-220℃, more preferably 160-210℃, and even more preferably 170-210℃.

[0051] Using α,ω-dihydroxypolysiloxane as raw material, the pre-depressurization absolute pressure is preferably 50-100 Pa, more preferably 50-80 Pa, and even more particularly preferably 50-60 Pa.

[0052] Using α,ω-dihydroxypolysiloxane as raw material, the de-lowering temperature is preferably 160-230℃, more preferably 170-220℃, and even more preferably 180-210℃.

[0053] Using α,ω-dihydroxypolysiloxane as raw material, the absolute pressure of the de-depletion is preferably 20-100 Pa, more preferably 20-80 Pa, and even more preferably 20-60 Pa.

[0054] Using α,ω-dihydroxypolysiloxane as raw material, the desliming time is preferably 0.5-2h, more preferably 1-2h, and particularly preferably 1.5-2h.

[0055] The benefits and effects of this invention are as follows:

[0056] 1. The biaxial stirrer designed in this invention is applied for the first time in the synthesis of ultra-high viscosity polysiloxanes. It has good mixing and interface renewal capabilities for ultra-high viscosity polysiloxanes, and solves the problem that current industrial reactors cannot be stirred. The resulting product has a more uniform molecular weight distribution and more stable quality.

[0057] 2. This invention employs a twin-screw extruder for pre-desalination and a second twin-shaft agitator for dedesalination. The twin-screw pre-desalination reduces volatile matter to ~1-3%, creating innovative ultra-high vacuum conditions for the second twin-shaft agitator dedesalination. The second twin-shaft agitator dedesalination exhibits excellent mixing and interfacial renewal capabilities for ultra-high viscosity polysiloxanes, extending residence time from seconds to hours, reducing low molecular weight polysiloxanes to low content levels (<100ppm). Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the process flow of the polysiloxane production system of the present invention;

[0059] Figure 2 This is a schematic diagram of the structure of the first dual-shaft stirrer of the present invention;

[0060] Figure 3 This is a cross-sectional view of the first dual-shaft stirrer of the present invention;

[0061] Figure 4 This is a schematic diagram of the twin-screw extruder of the present invention;

[0062] Figure 5 This is a schematic diagram of the structure of the second dual-shaft stirrer of the present invention;

[0063] Figure 6This is a cross-sectional view of the second dual-shaft stirrer of the present invention;

[0064] The components include: a prepolymer reactor 1; a first biaxial stirrer 2 and a second biaxial stirrer 4; cylinders 2-1 and 4-1; end caps 2-2-1, 2-2-2, 4-2-1, and 4-2-2; a first stirring shaft 2-3-1 and 4-3-1; a second stirring shaft 2-3-2 and 4-3-2; stirring rods 2-4-1, 2-4-2, 2-4-3, 4-4-1, and 4-4-2; stirring discs 2-5-1, 2-5-2, 2-5-3, 2-5-4, 2-5-5, 2-5-6, 4-5-1, and 4-5-2; sealing components 2-6-1, 2-6-2, 2-6-3, 2-6-4, 4-6-1, 4-6-2, 4-6-3, and 4-6-4; and a descaling unit. Deviation chambers 2-7-1, 2-7-2, 2-7-3, 4-7-1, 4-7-2, 4-7-3; Heating medium inlet 2-8-1, 4-8-1; Heating medium outlet 2-8-2, 4-8-2; Material inlet 2-9, 4-9; Discharge screw 2-10, 4-10; Terminator feed inlet 2-10-1, 4-10-1; Material outlet 2-10-2, 4-10-2; Twin-screw extruder 3; Twin-screw extruder feed inlet 3-1; Gas feed inlet 3-2; Deviation ports 3-3-1, 3-3-2; Material outlet 3-3; Metering pumps 5-1, 5-2, 5-3; First gear pump 6; Second gear pump 7; Vacuum system 8, 9, 10. Detailed Implementation

[0065] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0066] like Figure 1As shown, a polysiloxane production system, based on the characteristics of material viscosity and volatile content during the preparation process, utilizes the design of a first bi-screw extruder 2, a second bi-screw extruder 4, and a screw devolatilization mechanism, along with control of polymerization and de-volatilization conditions, to produce ultra-high viscosity, ultra-low volatile polysiloxanes within the optimal operating range of the equipment. The system employs a pre-de-volatilization method using a twin-screw extruder 3 and a second bi-screw extruder 4. The pre-de-volatilization using the twin-screw extruder 3 reduces the volatile content to ~1-3%, creating innovative ultra-high vacuum conditions for the de-volatilization using the second bi-screw extruder 4. The de-volatilization using the second bi-screw extruder 4 exhibits excellent mixing and interface renewal capabilities for ultra-high viscosity polysiloxanes, extending residence time from seconds to hours, and reducing low molecular weight to low content levels (<100ppm). The end-capping agent, siloxane, and catalyst are metered and fed into the prepolymer reactor 1. After prepolymerization, they are fed into the first twin-shaft agitator 2 for polymerization. After polymerization, the polysiloxane semi-finished product is transported to the twin-screw extruder 3 for polymerization termination and pre-degradation, and then fed into the second twin-shaft agitator 4 for degradation. After degradation, the polysiloxane is cooled, filtered, and discharged to obtain the final product. The low-molecular-weight molecules separated from the pre-degradation and degradation processes are condensed and recovered, and returned to the polymerization system for reuse.

[0067] A polysiloxane production system includes a prepolymer reactor 1, a first gear pump 6, a first twin-screw agitator 2, a twin-screw extruder 3, a second twin-screw agitator 4, and a second gear pump 7 connected in sequence by pipelines; the prepolymer reactor 1 is also connected to several metering pumps 5-1, 5-2, and 5-3 for feeding; the twin-screw extruder 3 is equipped with a vacuum system 9;

[0068] like Figure 2-3The first dual-shaft agitator 2 includes two parallel agitation shafts 2-3-1 and 2-3-2 arranged within the cylinder 2-1. Each agitation shaft 2-3-1 and 2-3-2 is equipped with several agitation components, including agitation discs 2-5-1, 2-5-2, 2-5-3, 2-5-4, 2-5-5, and 2-5-6, and agitation rods 2-4-1, 2-4-2, and 2-4-3. The agitation discs 2-5-1, 2-5-3, and 2-5-5 are fixed... The first stirring shaft 2-3-1 is fixed, and the stirring discs 2-5-2, 2-5-4, and 2-5-6 are fixed on the second stirring shaft 2-3-2. The cylinder 2-1 is divided into three sections: A, B, and C. The cross-sectional areas of the stirring rods 2-4-1, 2-4-2, and 2-4-3 decrease sequentially from section A to section B to section C. The stirring discs 2-5-1 and 2-5-2 are located in section A, the stirring discs 2-5-3 and 2-5-4 are located in section B, and the stirring discs 2-5-5 and 2-5-6 are located in section C. The gaps between the mixing discs and the cylinder 2-1 increase sequentially from section A to section B to section C, with the gaps between mixing discs 2-5-1 and 2-5-2 in section A and the cylinder 2-1 being less than 4mm. The mixing rods 2-4-1, 2-4-2, and 2-4-3 include a mixing beam and a first vertical rod and a second vertical rod fixed to both ends of the mixing beam. The first and second vertical rods are perpendicular to the mixing beam, and the mixing beam is vertically installed on the outer circumference of the mixing discs 2-5-1, 2-5-3, and 2-5-5, respectively, and the cylinder 2-1. The first and second vertical rods are fitted together so that they are located on both sides of the stirring plates 2-5-1, 2-5-3, and 2-5-5. The first and second vertical rods are perpendicular to and point towards the first stirring shaft 2-3-1 or the second stirring shaft 2-3-2. End caps 2-2-1 and 2-2-2 are provided at the ends of the cylinder 2-1. The first stirring shaft 2-3-1 and the second stirring shaft 2-3-2 extend out of the cylinder 2-1 through sealing components 2-6-1, 2-6-2, 2-6-3, and 2-6-4 and are connected to the power mechanism.

[0069] Along the direction of the first stirring shaft 2-3-1 and the second stirring shaft 2-3-2, the second vertical rod on the first stirring shaft 2-3-1 is located between the stirring plate on the second stirring shaft 2-3-2 and the first vertical rod, so that when the first stirring shaft 2-3-1 and the second stirring shaft 2-3-2 are rotated, the second vertical rod on the first stirring shaft 2-3-1 meshes with the first vertical rod on the second stirring shaft 2-3-2.

[0070] The cylinder 2-1 has a material inlet 2-9 on one side and a discharge screw 2-10 on the other side; the discharge screw 2-10 has a terminator inlet 2-10-1 in the middle and a material outlet 2-10-2 in the middle.

[0071] The outer side of the first twin-shaft agitator 2 is provided with a jacket or heat tracing pipe to compensate for latent heat dissipation.

[0072] The cylinder 2-1 also has a heating medium inlet 2-8-1 and a heating medium outlet 2-8-2. The first stirring shaft 2-3-1 and the second stirring shaft 2-3-2 are both hollow structures, so that the heating medium is introduced into the hollow structure. The heating medium is saturated water vapor or heat transfer oil.

[0073] The first dual-shaft stirrer 2 has three openings on its upper side, which are connected to devolatilization chambers 2-7-1, 2-7-2, and 2-7-3. Each devolatilization chamber is connected to the vacuum system 8.

[0074] like Figure 5-6 The second biaxial mixer 4 is similar to the first biaxial mixer 2, including two parallel mixing shafts 4-3-1 and 4-3-2 arranged inside the cylinder 4-1. Each mixing shaft 4-3-1 and 4-3-2 is equipped with several mixing components, including mixing discs 4-5-1, 4-5-2, 4-5-3, 4-5-4, 4-5-5, 4-5-6 and mixing rods 4-4-1, 4-4-2, 4-4-3. Mixing discs 4-5-1, 4-5-3, and 4-5-5 are fixed to the first mixing shaft 4-3-1, and mixing discs 4-5-2, 4-5-4, and 4-5-6 are fixed to the second mixing shaft 4-3-2. Mixing discs 4-5-1 and 4-5-2 are located in section A, mixing discs 4-5-3 and 4-5-4 are located in section B, and mixing discs 4-5-5 and 4-5-6 are located in section C. The gap between the mixing disc and the cylinder 4-1 is <4mm; the mixing rods 4-4-1, 4-4-2, and 4-4-3 include a mixing beam and a first vertical rod and a second vertical rod fixed at both ends of the mixing beam. The first vertical rod and the second vertical rod are perpendicular to the mixing beam. The mixing beam is vertically installed on the outer circumference of the mixing discs 4-5-1, 4-5-3, and 4-5-5 and fits against the cylinder 4-1, so that the first vertical rod and the second vertical rod are located on both sides of the mixing discs 4-5-1, 4-5-3, and 4-5-5. The first vertical rod and the second vertical rod are perpendicular to and point towards the first mixing shaft 4-3-1 or the second mixing shaft 4-3-2; end caps 4-2-1 and 4-2-2 are provided at the ends of the cylinder 4-1; the first mixing shaft 4-3-1 and the second mixing shaft 4-3-2 extend out of the cylinder 4-1 through sealing components 4-6-1, 4-6-2, 4-6-3, and 4-6-4 and are connected to the power mechanism.

[0075] Along the direction of the first stirring shaft 4-3-1 and the second stirring shaft 4-3-2, the second vertical rod on the first stirring shaft 4-3-1 is located between the stirring plate on the second stirring shaft 4-3-2 and the first vertical rod, so that when the first stirring shaft 4-3-1 and the second stirring shaft 4-3-2 are rotated, the second vertical rod on the first stirring shaft 4-3-1 meshes with the first vertical rod on the second stirring shaft 4-3-2;

[0076] The cylinder 4-1 has a material inlet 4-9 on one side and a discharge screw 4-10 on the other side; the discharge screw 4-10 has a terminator inlet 4-10-1 in the middle and a material outlet 4-10-2 in the middle.

[0077] The outer side of the second twin-shaft agitator 4 is equipped with a jacket or heat tracing pipe to compensate for latent heat dissipation.

[0078] The cylinder 4-1 also has a heating medium inlet 4-8-1 and a heating medium outlet 4-8-2. The first stirring shaft 4-3-1 and the second stirring shaft 4-3-2 are both hollow structures, so that the heating medium is introduced into the hollow structure. The heating medium is saturated water vapor or heat transfer oil.

[0079] The second twin-shaft stirrer 4 has three openings on its upper side, which are connected to devolatilization chambers 4-7-1, 4-7-2, and 4-7-3. Each devolatilization chamber is connected to the vacuum system 10.

[0080] The terminator feed port 4-10-1 is a liquid atomizing nozzle, or one or both of a gas pressurization device.

[0081] There are 3 metering pumps.

[0082] like Figure 4 The twin-screw extruder 3 includes two counter-rotating, meshing screws, and an extruder barrel composed of several second and third barrels.

[0083] The extruder barrel is composed of nine sections of second and third barrels, specifically, the second barrel, second barrel, third barrel, second barrel, second barrel, third barrel, second barrel, third barrel, and second barrel connected in sequence; the first section of the second barrel has a twin-screw extruder inlet 3-1; the third section of the third barrel has a gas feed inlet 3-2; the sixth and eighth sections of the third barrel have devolatilization ports 3-3-1 and 3-3-2, respectively; and the ninth section of the second barrel has a material outlet 3-3.

[0084] The first twin-shaft stirrer 2 is basically the same as the second twin-shaft stirrer 4, except that:

[0085] like Figure 3 In the first dual-shaft mixer 2, the cross-sectional shape of the mixing plates 2-5-1 and 2-5-2 in area A is circular, the cross-sectional shape of the mixing plates 2-5-3 and 2-5-4 in area B is regular polygon, and the cross-sectional shape of the mixing plates 2-5-5 and 2-5-6 in area C is regular polygon with concave sides.

[0086] like Figure 6In the second dual-shaft mixer 4, the cross-sectional shape of the mixing discs 4-5-1 and 4-5-2 in area A is a regular polygon, the cross-sectional shape of the mixing discs 4-5-3 and 4-5-4 in area B is a regular polygon with concave sides, and the cross-sectional shape of the mixing discs 4-5-5 and 4-5-6 in area C is a rod-shaped cross-section and the cross-sectional shape of the mixing discs 4-5-6 is a regular polygon with concave sides.

[0087] The terminator inlet 2-10-1 is a liquid atomizing nozzle, and in some embodiments, a gas pressurizing device may also be used. The gas pressurizing device preferably has a gas pressure of 0.1-1 MPa, more preferably 0.1-0.6 MPa, and even more particularly preferably 0.2-0.4 MPa.

[0088] In use, the end-capping agent and siloxane are preheated to a certain temperature by metering pumps 5-1, 5-2, and 5-3 respectively, and then fed into the prepolymerization reactor 1. The catalyst, after dilution and without preheating, is metered into the prepolymerization reactor 1. The end-capping agent, siloxane, and catalyst are stirred and mixed in the prepolymerization reactor 1 and polymerized to a certain extent. Then, they are fed into the first twin-screw extruder 2 by the first gear pump 6. After reaching polymerization equilibrium under certain polymerization temperature and residence time or vacuum conditions, the polymer is fed into the twin-screw extruder 3 through the discharge screw 2-10. The terminator is metered and added through the terminator feed port 2-10-1 of the discharge screw 2-10 and the gas feed port 3-2 of the twin-screw extruder 3 to terminate the reaction. After pre-degradation under certain vacuum and temperature, the polymer is fed into the second twin-screw extruder 4 and degraded under certain temperature, time, and vacuum system 10. After degradation, the polymer is discharged through the discharge screw 4-10, the second gear pump 7, filtration, and cooling to obtain ultra-high molecular weight, ultra-low volatile polysiloxane.

[0089] Using cyclosiloxane as raw material, the addition amount is 80-150 kg / h, and the water content of cyclosiloxane is 10-80 ppm; the catalyst is potassium siloxaneol, sodium siloxaneol, or cesium siloxaneol, added at 10-50 ppm; the diluent is cyclosiloxane, with a mass solubility controlled at 10-100 g / L; the prepolymerization reaction temperature is 80-140℃; the average residence time of the prepolymerization reaction is 0.5-2 h; the stirring speed of the prepolymerization reaction is 20-100 rpm; the polymerization reaction temperature is 140-180℃; the preferred average residence time of polymerization is 2-5 h; the terminator is silicone phosphate or phosphoric acid, added at 10-50 ppm; the preferred absolute pressure for pre-degradation is 100-500 Pa; the preferred degradation temperature is 160-230℃; the preferred absolute pressure for degradation is 20-80 Pa; and the preferred degradation time is 0.5-2 h.

[0090] The reaction process uses α,ω-dihydroxypolysiloxane as raw material, with an addition rate of 100-200 kg / h; the catalyst is phosphazene chloride catalyst, with an addition rate of 2-20 ppm; the catalyst diluent is one or more of ethyl acetate, methyl acetate, ethyl formate, toluene, benzene, and xylene, with a mass concentration controlled at 10-100 g / L; the prepolymerization reaction temperature is 0-50℃; the prepolymerization reaction time is 0.5-2 h; the prepolymerization reaction stirring rate is 20-100 rpm; and the polymerization temperature is 80-180℃. The polymerization absolute pressure is preferably 20-100 Pa; the polymerization time is preferably 10-120 min; the terminator is one or more of diethylamine, triethylamine, tri-n-butylamine, hexamethyldisilazane, and cyclotrisilazane, and the amount of terminator added is 3-30 ppm; the pre-degradation temperature is preferably 160-220℃; the pre-degradation absolute pressure is preferably 50-100 Pa; the degradation temperature is preferably 160-230℃; the degradation absolute pressure is preferably 20-100 Pa; and the degradation time is preferably 0.5-2 h.

[0091] Method for determining the molecular weight of polysiloxanes: Based on the relative molecular weight range of the sample, prepare polystyrene and low molecular weight cyclosiloxane standards, establish a suitable fitting calibration curve, then weigh an appropriate amount of sample, dissolve it in toluene, prepare a sample test solution with a mass concentration of 2 mg / ml, and test it using a gel permeation chromatograph with a differential detector. Finally, use the established calibration curve to calculate the molecular weight and molecular weight distribution of the sample.

[0092] Test method for volatile matter of polysiloxane: Using a balance accurate to 0.001g, weigh about 2g of polysiloxane in a glass petri dish with a diameter of 75mm, place it in a forced-air oven at 105, 150 or 200℃ for 3 or 4 hours, weigh it again, and calculate the proportion of mass loss to the initial mass.

[0093] Test method for low molecular weight cyclic content of polysiloxane: 0.5g polysiloxane is dissolved in 10ml acetone, extracted at room temperature for 24h, and the supernatant is taken for GC analysis; D4-D6 are quantitatively analyzed, and D7-D10 are semi-quantitatively analyzed.

[0094] Example 1: Synthesis of Ultra-High Molecular Weight Methylvinyl Silicone Rubber

[0095] In this embodiment, the process flow is as follows: Figure 1 As shown, the first biaxial stirrer 2 and the second biaxial stirrer 4 are as follows: Figure 2-3 As shown in Figures 5-6, the twin-screw extruder 3... Figure 4 As shown, there are 5 metering pumps.

[0096] Methylcyclosiloxane (Me2SiO) 4-5The moisture content is 20-30 ppm, and the flow rate is controlled at 100 kg / h using a metering pump; (MeViSiO) 3-4 The water content is 20-30 ppm, and the flow rate is controlled at 0.25 kg / h using a metering pump; Vi(Me2SiO) 10-20 Me2SiVi, with a water content of 20-30 ppm, is metered and pumped at a flow rate controlled at 0.42 kg / h. It is then preheated to 130°C in a preheater before being fed into prepolymer reactor 1. A cyclosiloxane solution of potassium siloxane alkoxide catalyst, with a mass concentration of 10 g / L, is metered and pumped at a flow rate controlled at 3.3 mL / min. It is fed directly into prepolymer reactor 1 without preheating. The prepolymerization reaction is controlled at 130°C, with a stirring speed of 100 rpm and an average residence time of 1 h. After prepolymerization, the material is pumped through the first gear pump 6 and fed into the twin-shaft stirrer 2 via material inlets 2-9. The polymerization process is then controlled. The polymerization temperature was set at 160℃, the twin-shaft agitator 2 rotated at 20 rpm, and the average residence time was 3 hours. The vacuum system was shut off, and atmospheric pressure polymerization was carried out. 180℃ heat transfer oil was introduced into the heating medium inlet 2-8-1 for heating and atmospheric pressure polymerization. After polymerization, the material was connected to the twin-screw extruder inlet 3-1 via the material discharge screw 2-10 outlet 2-10-2. The material entered the twin-screw extruder 3, with a silica-based phosphate mass concentration of 10 g / L, and the feed rate was controlled at 4.0 mL / min. The material was added through the feed port 2-10-2 of the discharge screw 2-10. The material is premixed in screw 2-10 and then fed into twin-screw extruder 3 for uniform mixing. A carbon dioxide gas terminator is added through the gas feed port 3-2 in section 3 of the cylinder, with the pressure controlled at 0.3 MPa. After termination, the material undergoes pre-descaling through sections 6 and 8 of the cylinder, with a descaling vacuum of 200-300 Pa and a temperature of 170°C. After pre-descaling, the material is connected to the material outlet 3-3 of twin-screw extruder 3 and the feed port 4-9 of the twin-shaft agitator 4. The material enters the twin-shaft agitator 4, where the descaling temperature is 180°C, the vacuum is 50 Pa, the agitator 4 rotates at 30 rpm, and the average residence time after descaling is 1.5 hours. The material is degraded by introducing 210℃ heat transfer oil into the heating medium inlet 4-8-1 for heating. After degradation, the material is discharged through the material outlet 4-10-2 of the twin-shaft agitator 4 and connected to the second gear pump 7 via the discharge screw 4-10. The outlet of the second gear pump 7 is connected to the filter, and the filter outlet is connected to the cooler. Finally, the ultra-low volatile matter ultra-high molecular weight methyl vinyl silicone rubber is discharged, with a molecular weight of 590 kDa, a vinyl content of 0.24%, a volatile matter content of (200℃, 2g, 3h) < 0.1%, and a D3-D10 ring content of 36.8 ppm.

[0097] Example 2: Synthesis of Ultra-High Molecular Weight Methylphenyl Silicone Rubber

[0098] In this embodiment, the process flow is as follows: Figure 1As shown, the first biaxial stirrer 2 and the second biaxial stirrer 4 are as follows: Figure 2-3 As shown in Figures 5-6, the twin-screw extruder 3... Figure 4 As shown, there are 5 metering pumps.

[0099] Methylcyclosiloxane (Me2SiO)4, with a water content of 20-30 ppm, was metered at a flow rate of 82 kg / h; molten (MePhSiO)3, with a water content of 20-30 ppm, was metered at a flow rate of 17.6 kg / h; (MeViSiO) 3-4 The water content is 20-30 ppm, and the flow rate is controlled at 0.5 kg / h using a metering pump; Vi(Me2SiO) 10-20Me2SiVi, with a water content of 20-30 ppm, is metered and pumped at a flow rate of 0.32 kg / h. It is then preheated to 130°C in a preheater before being fed into prepolymer reactor 1. A cyclosiloxane solution of potassium siloxane alkoxide catalyst, with a mass concentration of 10 g / L, is metered and pumped at a flow rate of 6 mL / min without preheating and directly fed into prepolymer reactor 1. The prepolymerization reaction is controlled at 100°C, a stirring speed of 100 rpm, and an average residence time of 1 h. After prepolymerization, the material is pumped through the first gear pump 6 and fed into the twin-shaft stirrer 2 via material inlets 2-9, controlling the polymerization temperature. At 160℃, with the twin-shaft stirrer 2 rotating at 20 rpm and an average residence time of 3 hours, the vacuum system 8 was shut off, and atmospheric pressure polymerization was carried out. 180℃ heat transfer oil was introduced into the heating medium inlet 2-8-1 for heating and atmospheric pressure polymerization. After polymerization, the material, with a silicon-based phosphate mass concentration of 10 g / L, was added through the material screw outlet 2-10, the melt pump, and the twin-screw extruder inlet 3-1, connected to the screw outlet 2-10. The feed rate was controlled at 8 mL / min. The material was added through the discharge screw 2-10 inlet 2-10-2 and premixed through the discharge screw 2-10. The material is then fed into twin-screw extruder 3 for uniform mixing. A carbon dioxide gas terminator is added through the gas feed port 3-2 of the third cylinder section, with the pressure controlled at 0.3 MPa. After termination, the material undergoes pre-descaling through the sixth and eighth cylinder sections, with a descaling vacuum of 200-300 Pa and a temperature of 180°C. After pre-descaling, the material is connected to the material outlet 3-3 of twin-screw extruder 3 and the material inlet 4-9 of twin-shaft agitator 4. The material enters twin-shaft agitator 4, where the descaling temperature is 200°C, the vacuum is 50 Pa, the agitator speed is 30 rpm, and the average residence time is 1.5 hours. Descaling is then carried out. 210℃ heat transfer oil is input through the heat medium inlet 4-8-1 for heating; after desulfurization, the material is connected to the second gear pump 7 through the discharge screw 4-10 via the material outlet 4-10-2 of the twin-shaft agitator 4. The outlet of the second gear pump 7 is connected to the filter, and the filter outlet is connected to the cooler. Finally, the ultra-low volatile matter ultra-high molecular weight methyl vinyl silicone rubber is discharged, with a molecular weight of 680 kDa, a vinyl content of 0.46%, a phenyl content of 10%, a volatile matter content of (200℃, 2g, 3h) <0.1%, and a D3-D10 cyclic content of 41.2 ppm.

[0100] Example 3: Synthesis of Ultra-High Molecular Weight 107 Silicone Rubber

[0101] In this embodiment, the process flow is as follows: Figure 1 As shown, the first biaxial stirrer 2 and the second biaxial stirrer 4 are as follows: Figure 2-3 As shown in Figures 5-6, a twin-screw extruder is as follows: Figure 4 As shown, there are 2 metering pumps.

[0102] HO(Me2SiO) 10-20H, with a flow rate controlled at 100 kg / h by a metering pump, is fed into prepolymer reactor 1; ethyl acetate solution of the catalyst, phosphazene silicochloride, with a mass concentration of 10 g / L, is also fed into prepolymer reactor 1 with a flow rate controlled at 0.62 mL / min by a metering pump; the prepolymerization reaction is controlled at 0-30℃, a stirring speed of 100 rpm, and an average residence time of 1 h. After prepolymerization, the material is fed into twin-shaft stirrer 2 through material inlets 2-9 via the first gear pump 6. The polymerization temperature is controlled at 150℃, the twin-shaft stirrer 2 rotates at 120 rpm, and the average residence time is 1 h. The residence time is 0.5 hours, and the vacuum is 60 Pa for vacuum polymerization. 170℃ heat transfer oil is introduced into the heating medium inlet 2-8-1 for compensated heating, and atmospheric pressure polymerization is carried out. After polymerization, the material enters the twin-screw extruder 3 through the material screw outlet 2-10, the melt pump, and the feed inlet 3-1 of the twin-screw extruder 3. The cyclosiloxane concentrate in the cyclotrisilazane has a mass concentration of 20 g / L, and the feed rate is controlled at 6.2 mL / min. It is added through the feed port 2-10-2 of the discharge screw 2-10 and discharged through the discharge screw. Premixing is performed on screws 2-10, followed by uniform mixing in sections 1-5 of the twin-screw extruder 3. The gas feed port 3-2 in section 3 is then blind-plugged. After termination, pre-desalination is performed through sections 6 and 8, with a desalization vacuum of 50-60 Pa and a temperature of 180°C. Following pre-desalination, the material is connected to the material outlet 3-3 of the twin-screw extruder 3 and the feed port 4-9 of the twin-shaft agitator. The material enters the twin-shaft agitator 4, where the desalization temperature is 200°C, the vacuum is 50 Pa, the agitator speed is 30 rpm, and the average residence time is 1.5 hours. After descaling, 210℃ heat transfer oil is introduced into the heating medium inlet 4-8-1 for compensatory heating. After descaling, the material is connected to the second gear pump 7 through the material outlet 4-10-2 of the twin-shaft agitator 4 via the discharge screw 4-10. The outlet of the second gear pump 7 is connected to the filter, and the filter outlet is connected to the cooler. Finally, the ultra-low volatile matter ultra-high molecular weight 107 silicone rubber is discharged, with a molecular weight of 1160KDa, a volatile matter content of (200℃, 2g, 3h) <0.1%, and a D3-D10 ring content of 33.4ppm.

[0103] Example 4: Synthesis of Ultra-High Molecular Weight Fluorosilicone Rubber

[0104] In this embodiment, the process flow is as follows: Figure 1 As shown, the first biaxial stirrer 2 and the second biaxial stirrer 4 are as follows: Figure 2-3 As shown in Figures 5-6, a twin-screw extruder is as follows: Figure 4 As shown, there are 3 metering pumps.

[0105] HO(C2H4CF3MeSiO) 10-20 H is fed into prepolymer reactor 1 at a flow rate controlled at 100 kg / h via a metering pump; Me(Me2SiO) 10-20Me2SiMe, with a water content of 20-30 ppm, is fed into prepolymer reactor 1 at a flow rate controlled at 0.34 kg / h using a metering pump. An ethyl acetate solution of the catalyst, phosphazene silicochloride, with a mass concentration of 10 g / L, is also fed into prepolymer reactor 1 at a flow rate controlled at 0.55 mL / min using a metering pump. The prepolymerization reaction is controlled at 0-30℃, with a stirring speed of 100 rpm and an average residence time of 1 h. After prepolymerization, the material is fed into a twin-shaft stirrer 2 via material inlets 2-9 using a first gear pump 6. The polymerization temperature is controlled at 150℃, and the mixture is stirred by the twin shafts. The reactor operates at 120 rpm, with an average residence time of 0.5 h and a vacuum of 60 Pa for vacuum polymerization. 170°C heat transfer oil is fed into the heating medium inlet 2-8-1 for compensated heating, and atmospheric pressure polymerization is carried out. After polymerization, the material enters the twin-screw extruder 3 through the material screw outlet 2-10, the melt pump, and the twin-screw extruder inlet 3-1. The cyclosiloxane concentrate in the cyclotrisilazane has a mass concentration of 20 g / L, and the feed rate is controlled at 5.5 mL / min. The material is discharged through the feed port 2-1 of the discharge screw 2-10. 0-2 is added and premixed through discharge screws 2-10, then enters the first 5 sections of the twin-screw extruder 3 for uniform mixing. The gas feed port 3-2 of the third section is blind-plugged and closed. After termination, it is pre-de-cooled through sections 6 and 8, with a de-cooling vacuum of 50-60 Pa and a temperature of 170℃. After pre-de-cooling, the material is connected to the material outlet 3-3 of the twin-screw extruder 3 and the feed port 4-9 of the twin-shaft agitator. The material enters the twin-shaft agitator 4, with a de-cooling temperature of 180℃, a vacuum of 50 Pa, a rotation speed of 30 rpm, and an average residence time of 1 minute. After 0.5 hours, the material is degraded by inputting 210℃ heat transfer oil into the heating medium inlet 4-8-1 for compensatory heating. After the degradation is completed, the material is connected to the second gear pump 7 through the discharge screw 4-10 via the material outlet 4-10-2 of the twin-shaft agitator 4. The outlet of the second gear pump 7 is connected to the filter, and the filter outlet is connected to the cooler. Finally, the ultra-low volatile matter ultra-high molecular weight fluorosilicone rubber is discharged, with a molecular weight of 610KDa, a volatile matter content of (200℃, 2g, 3h) <0.1%, and a D3-D10 ring content of 52.5ppm.

[0106] Comparative Example 1

[0107] This comparative example uses 1m 3 The polymerization reaction was carried out in a polymerization reactor, and the low molecular weight molecules were removed by a strip devolatilizer. The reaction conditions were in accordance with those in Example 1 to produce ultra-high molecular weight methyl vinyl silicone rubber.

[0108] Methylcyclosiloxane (Me2SiO) 4-5 The moisture content is 20-30 ppm, and the material quantity is measured and prepared in 500 kg using a weighing module; (MeViSiO) 3-4The moisture content is 20-30 ppm, and the material quantity is 1.25 kg, measured by a weighing module; Vi(Me2SiO) 10-20 Me2SiVi, with a water content of 20-30 ppm, was weighed at a rate of 2.05 kg and preheated to 130°C in a preheater before being fed into the polymerization reactor. A cyclosiloxane solution of potassium siloxane alkoxide catalyst, with a mass concentration of 10 g / L, was weighed at a rate of 0.99 kg and directly fed into the polymerization reactor. The polymerization reaction was controlled at 160°C, a stirring rate of 20 rpm, and a polymerization equilibrium time of 3 hours. After polymerization, the silica-based phosphate ester had a mass concentration of 10 g / L, and 1.2 kg was weighed at a rate of 1.2 kg. The material is directly fed into the polymerization reactor by a transfer pump. At 160℃ and a stirring rate of 20 rpm, the neutralization reaction is carried out for 1 hour. After neutralization, the flow rate is controlled at 100 kg / h by a bottom discharge pump of the polymerization reactor. After being preheated to 180℃ by a preheater, the material enters the strip devolatilizer. Under 180℃ and 500 Pa vacuum conditions, the low molecular weight is removed. Finally, the ultra-high molecular weight methyl vinyl silicone rubber is discharged, with a molecular weight of 586 kDa, a vinyl content of 0.24%, a volatile content of 1.46% (200℃, 2g, 3h), and a D3-D10 cyclic content of 12650 ppm.

[0109] Comparative Example 2

[0110] This comparative example uses a 500L kneader for polymerization and de-molecular weight reduction, and the reaction conditions are the same as in Example 2 to produce ultra-high molecular weight methylphenyl silicone rubber.

[0111] Methylcyclosiloxane (Me2SiO)4, with a water content of 20-30 ppm, was prepared in a quantity of 164 kg using a weighing module; melted (MePhSiO)3, with a water content of 20-30 ppm, was prepared in a quantity of 35.2 kg using a weighing module; (MeViSiO) 3-4 The moisture content is 20-30 ppm, and the material quantity is measured and prepared in 1 kg using a weighing module; Vi(Me2SiO) 10-20Me2SiVi, with a water content of 20-30 ppm, was prepared in quantities of 0.64 kg using a weighing module. It was then pumped to a preheater and preheated to 130°C before being fed into a kneader. A cyclosiloxane solution of potassium siloxane alkoxide catalyst, with a mass concentration of 10 g / L, was prepared in quantities of 1.8 kg using a weighing module and fed directly into the kneader for polymerization without preheating. The polymerization reaction was controlled at 160°C, a stirring rate of 20 rpm, and a polymerization equilibrium time of 4 hours. After polymerization, the mass concentration of the silanized phosphate ester was 10 g / L. L, 2.2Kg of material was weighed and fed directly into the kneader by the conveying pump. The neutralization reaction was carried out at 160℃ and 20rpm for 1 hour. After neutralization, the kneader was heated to 200℃ and de-molecularly degraded under a vacuum of 500Pa for 8 hours. Finally, ultra-high molecular weight methylphenyl silicone rubber was discharged with a molecular weight of 683KDa, a vinyl content of 0.46%, a volatile content of 1.18% (200℃, 2g, 3h), and a D3-D10 ring content of 8790ppm.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A polysiloxane production system, characterized in that, The system includes a prepolymer reactor, a first gear pump, a first twin-screw agitator, a twin-screw extruder, a second twin-screw agitator, and a second gear pump, which are connected in sequence via pipelines. The prepolymer reactor is also connected to several metering pumps for feeding. The twin-screw extruder is equipped with a vacuum system. The first and second twin-screw agitators are twin-screw agitators. The first and second biaxial mixers include two parallel stirring shafts arranged in the cylinder. Each stirring shaft is provided with a plurality of stirring components, each stirring component including a stirring plate and a stirring rod. The stirring plate is fixed on the first and second stirring shafts. The stirring rod includes a stirring beam and a first and a second vertical rod fixed at both ends of the stirring beam. The first and second vertical rods are perpendicular to the stirring beam. The stirring beam is vertically installed on the outer circumference of the stirring plate and fits against the cylinder, such that the first and second vertical rods are located on both sides of the stirring plate. The first and second vertical rods are perpendicular to and point towards the first or second stirring shaft. End caps are installed at the ends of the cylinder; The first and second stirring shafts extend out of the cylinder body through sealing components and are connected to the power mechanism; Along the direction of the first stirring shaft and the second stirring shaft, the second vertical rod on the first stirring shaft is located between the stirring plate on the second stirring shaft and the first vertical rod, so that when the first stirring shaft and the second stirring shaft are rotated, the second vertical rod on the first stirring shaft engages with the first vertical rod on the second stirring shaft. The cylinder has a material inlet on one side and a discharge screw on the other side; the discharge screw has a terminator inlet in the middle and a material outlet. The cylinder is divided into three sections: A, B, and C. The cross-sectional area of ​​the stirring rod decreases sequentially from section A to section B to section C. The gap between the stirring plate and the cylinder increases sequentially from section A to section B to section C, and the gap between the stirring plate and the cylinder in section A is <4mm; Using cyclosiloxane as raw material, the average residence time of the prepolymerization reaction is 0.5h-2h, and the average residence time of the polymerization reaction is 2h-5h. Alternatively, using α,ω-dihydroxypolysiloxane as raw material, the prepolymerization reaction time is 0.5h-2h, and the polymerization time is 10min-120min.

2. The polysiloxane production system according to claim 1, characterized in that, The outer side of the twin-shaft agitator is provided with a jacket or heat tracing pipe to compensate for latent heat dissipation.

3. The polysiloxane production system according to claim 1, characterized in that, The cylinder also has a heating medium inlet and a heating medium outlet. The first and second stirring shafts are hollow structures, allowing the heating medium to pass through the hollow structure. The heating medium is saturated steam or heat transfer oil.

4. The polysiloxane production system according to claim 1, characterized in that, The biaxial stirrer has an opening on its upper side, which connects to a devolatilization chamber. There are 1 to 3 devolatilization chambers, and each devolatilization chamber is connected to a vacuum system.

5. A polysiloxane production system according to claim 1, characterized in that, The terminator feed port is one or both of the following: a liquid atomizing nozzle or a gas pressurizing device.

6. A polysiloxane production system according to claim 1, characterized in that, The number of metering pumps is 3.

7. A polysiloxane production system according to claim 1, characterized in that, The twin-screw extruder includes two counter-rotating, meshing screws, and an extruder barrel composed of several second and third barrels.

8. A polysiloxane production system according to claim 7, characterized in that, The extruder barrel is composed of nine sections of second and third barrels, specifically, the second barrel, second barrel, third barrel, second barrel, second barrel, third barrel, second barrel, third barrel, and second barrel connected in sequence; the first section of the second barrel has a twin-screw extruder feed inlet; the third section of the third barrel has a gas feed inlet; the sixth and eighth sections of the third barrel have volatilization outlets; and the ninth section of the second barrel has a material outlet.

9. A polysiloxane production system according to claim 7, characterized in that, The twin-screw extruder has a length-to-diameter ratio of 20~50:1; a groove depth ratio (inner-to-outer diameter ratio) of 1.8; and a screw diameter of 50~100 mm. The feeding method is to feed from the tail of the screw and discharge from the root of the screw. The twin-screw termination section is equipped with 1-2 termination agent addition ports, and the neutralization length of each port is 10-20 times the screw diameter.

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