A dual shaft mixer and a system for removing volatile components from a polysiloxane

Abstract

The present application relates to a kind of double-shaft stirrer and the removal system of volatile in polysiloxane.The removal system of polysiloxane includes: first preheater, flash evaporator, first gear pump, second preheater, double-shaft stirrer, second gear pump and condenser connected in sequence.The removal system and removal method suitable for high, middle and low viscosity polysiloxane can efficiently remove volatile in polysiloxane.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polysiloxane volatile component removal, in particular to a double-shaft agitator and a polysiloxane volatile component removal system. BACKGROUND

[0002] The preparation of polysiloxane generally adopts an alkali catalytic equilibrium process, and after the reaction is completed, a large amount of oligomers and 15% or so of low molecular cyclic bodies such as octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) need to be removed. Domestic production generally adopts a single-stage or multi-stage falling strip type devolatilizer, a scraper type thin film evaporator, and a scraper type short path distillation for devolatilization, and the volatile component content after devolatilization is generally about 1.0-3.0%. With the development of organic silicon terminalization, the requirements of the semiconductor, medical, food and other fields are getting higher and higher, and even the requirement for the content of low molecular cyclic bodies is less than 100 ppm. Therefore, the further removal of polysiloxane volatile components is imperative.

[0003] Chinese patent CN102206349 discloses a kind of a, ω-dihydroxy polysiloxane purification method of falling and short path distillation in series of scraper type thin film devolatilization, at 50-90Pa, 20-50Pa in two stages, two-stage separation system, D4-D10 content reaches 50-120ppm;But this series of combined devolatilization method is only suitable for polysiloxane devolatilization below 200,000 mpa.s.

[0004] Chinese patent ZL201920744399.2 reports a kind of volatile component removal system and removal method of methyl vinyl silicone rubber, adopts falling strip devolatilizer flash predevolatilization, double screw secondary devolatilization method, which can remove volatile components of methyl vinyl silicone rubber to below 0.75%. This series of combined devolatilization method can be suitable for polysiloxane devolatilization of 100-5000 million mpa.s, but the main reason is that the screw residence time is short, the vacuum is low, and the volatile component can only be 0.2-0.5%, which cannot produce methyl vinyl raw rubber with cyclic body content less than 100 ppm. SUMMARY

[0005] The present application provides a double-shaft agitator and a polysiloxane volatile component removal system, which provides a removal system and method suitable for high, medium and low viscosity polysiloxane, and can efficiently remove volatile components in polysiloxane.

[0006] The double-shaft agitator comprises a first agitator shaft and a second agitator shaft arranged in parallel in a barrel, and a plurality of agitator pieces are arranged on the first agitator shaft and the second agitator shaft, wherein the agitator pieces comprise agitator discs and agitator rods, the agitator discs are fixed on the first agitator shaft and the second agitator shaft, the agitator rods comprise agitator beams and first vertical rods and second vertical rods fixed on both ends of the agitator beams, the first vertical rods and the second vertical rods are perpendicular to the agitator beams, the agitator beams are vertically installed on the outer circumferences of the agitator discs and are in close contact with the barrel, so that the first vertical rods and the second vertical rods are located on both sides of the agitator discs and are perpendicular to and point to the first agitator shaft or the second agitator shaft, end covers are arranged at the ends of the barrel, and the first agitator shaft and the second agitator shaft are connected with a power mechanism through sealing components and extend out of the barrel.

[0007] In the direction of the first agitator shaft and the second agitator shaft, the second vertical rod on the first agitator shaft is located between the agitator disc and the first vertical rod on the second agitator shaft, so that when the first agitator shaft and the second agitator shaft are rotated, the second vertical rod on the first agitator shaft is engaged with the first vertical rod on the second agitator shaft.

[0008] One side of the barrel is provided with a material feeding port, and the other side is provided with a discharging screw, and the discharging screw is provided with a material discharging port.

[0009] The barrel is divided into three sections A, B and C, the cross-sectional area of the agitator rod decreases in sequence from section A to section B to section C, the gap between the agitator disc and the barrel increases in sequence from section A to section B to section C, and the gap between the agitator disc in section A and the barrel is less than 4 mm.

[0010] Further, the agitator disc in section A is circular, the agitator disc in section B is elliptical, and the agitator disc in section C is a regular polygon.

[0011] Further, the barrel is further provided with three devolatilization chambers, and a second vacuum pumping unit is connected to the devolatilization chambers. The second vacuum pumping unit is connected to the exhaust port of the devolatilization chamber, and provides a vacuum condition for the devolatilization chamber. In some embodiments of the present application, the second vacuum pumping unit is a second vacuum pump. The present application does not have special limitations on the selection of the second vacuum pump, and any vacuum pump known to those skilled in the art can be used.

[0012] A polysiloxane removal system using the above-mentioned double-shaft agitator, comprising: a first preheater, a flash evaporator, a first gear pump, a second preheater, a double-shaft agitator, a second gear pump and a condenser connected in sequence. The flash evaporator is provided with a feed inlet, a discharge outlet and a devolatilization outlet. The feed inlet of the flash evaporator is connected with the discharge outlet of the preheater. The polysiloxane enters the flash evaporator through the feed inlet of the flash evaporator after preheating, and preliminary devolatilization is carried out under vacuum condition in the flash evaporator. The polysiloxane after devolatilization is discharged through the discharge outlet of the flash evaporator, and the volatile components are discharged through the devolatilization outlet of the flash evaporator.

[0013] Further, the flash evaporator is one of a falling strip devolatilizer, a wiped film evaporator and a short path distillation.

[0014] Further, the flash evaporator has a devolatilization outlet.

[0015] Further, the devolatilization outlet of the flash evaporator is connected with a first vacuum pumping unit. The flash evaporator is provided with a vacuum environment to carry out the first devolatilization. In some embodiments of the present application, the first vacuum pumping unit is a first vacuum pump. The present application does not have special limitations on the selection of the first vacuum pump, and a vacuum pump well known to those skilled in the art can be used.

[0016] The present application has the following beneficial effects:

[0017] After preheating, the polysiloxane enters the flash evaporator through the feed inlet of the flash evaporator, and the first devolatilization is carried out under vacuum condition in the flash evaporator. The polysiloxane after the first devolatilization is discharged through the discharge outlet of the flash evaporator, pumped into the preheater through the gear pump, preheated to the required temperature, and then enters the double-shaft agitator. The second devolatilization is carried out under vacuum condition in the double-shaft agitator. The polysiloxane after the second devolatilization is pumped into the condenser through the gear pump, cooled in the condenser, and then obtained is the ultra-low volatile polysiloxane. The devolatilization time reaches the order of hours, the volatile content is reduced to below 0.1 wt%, and the content of each of D4, D5 and D6 is reduced to below 50 ppm. Further, the volatile content can be reduced to below 0.05 wt%, and the content of each of D4, D5 and D6 can even be reduced to below 20 ppm. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a process flow diagram of a double-shaft agitator and a polysiloxane volatile removal system of the present application;

[0019] Figure 2 is a double-shaft agitator structure diagram of a double-shaft agitator and a polysiloxane volatile removal system of the present application;

[0020] Figure 3 is a cross-sectional view of a double-shaft agitator of a double-shaft agitator and a polysiloxane volatile removal system of the present application;

[0021] The components include: a first preheater 1; a flash evaporator 2; a first gear pump 3; a second preheater 4; a twin-shaft agitator 5; a cylinder 5-1; end caps 5-2-1 and 5-2-2; a first stirring shaft 5-3-1; a second stirring shaft 5-3-2; stirring rods 5-4-1, 5-4-2, and 5-4-3; stirring discs 5-5-2, 5-5-4, and 5-5-6; sealing components 5-6-1, 5-6-2, 5-6-3, and 5-6-4; devolatilization chambers 5-7-1, 5-7-2, and 5-7-3; a heating medium inlet 5-8-1; a heating medium outlet 5-8-2; a material inlet 5-9; a discharge screw 5-10; a second gear pump 6; a condenser 7; a first vacuum unit 8; and a second vacuum unit 9. Detailed Implementation

[0022] 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.

[0023] like Figures 2-3 As shown, the dual-shaft agitator 5 includes two parallel first agitation shafts 5-3-1 and 5-3-2 arranged inside the cylinder 5-1. Each of the first agitation shafts 5-3-1 and 5-3-2 is equipped with several agitation components, including agitation discs 5-5-2, 5-5-4, and 5-5-6, and agitation rods 5-4-1, 5-4-2, and 5-4-3. The agitation discs 5-5-2, 5-5-4, and 5-5-6 are fixed to the first agitation shafts 5-3-1 and 5-3-2. The agitation rods 5-4-1, 5-4-2, and 5-4-3 include a agitation beam and a first vertical rod and a second vertical rod fixed to both ends of the agitation beam. A first vertical rod and a second vertical rod are perpendicular to the stirring beam. The stirring beam is vertically installed on the outer circumference of the stirring pans 5-5-2, 5-5-4, and 5-5-6 and fits against the cylinder 5-1, so that the first vertical rod and the second vertical rod are located on both sides of the stirring pans 5-5-2, 5-5-4, and 5-5-6. The first vertical rod and the second vertical rod are perpendicular to and point towards the first stirring shaft 5-3-1 or the first stirring shaft 5-3-2. End caps 5-2-1 and 5-2-2 are provided at the ends of the cylinder 5-1. The first stirring shafts 5-3-1 and 5-3-2 extend out of the cylinder 5-1 through sealing components 5-6-1, 5-6-2, 5-6-3, and 5-6-4 and are connected to the power mechanism.

[0024] Along the direction of the first stirring shaft 5-3-1 and the first stirring shaft 5-3-2, the second vertical rod on the first stirring shaft 5-3-1 is located between the stirring plate on the first stirring shaft 5-3-2 and the first vertical rod, so that when the first stirring shaft 5-3-1 and the first stirring shaft 5-3-2 are rotated, the second vertical rod on the first stirring shaft 5-3-1 meshes with the first vertical rod on the first stirring shaft 5-3-2;

[0025] The barrel 5-1 has a material feeding port 5-9 on one side and a material discharging screw 5-10 on the other side; the material discharging screw 5-10 has a material discharging port.

[0026] The barrel 5-1 is divided into three sections A, B and C, the cross-sectional areas of the stirring rods 5-4-1, 5-4-2 and 5-4-3 decrease in order from section A to section B to section C; the gaps between the stirring discs 5-5-2, 5-5-4 and 5-5-6 and the barrel 5-1 increase in order from section A to section B to section C, and the gap between the stirring disc 5-5-2 of section A and the barrel 5-1 is less than 4 mm.

[0027] The stirring disc 5-5-1 of section A is circular, the stirring disc 5-5-3 of section B is elliptical, and the stirring disc 5-5-5 of section C is a regular polygon.

[0028] The barrel 5-1 also has three devolatilization chambers 5-7-1, 5-7-2 and 5-7-3, and the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 are connected to the second vacuum pumping unit 9.

[0029] The polysiloxane after the preliminary devolatilization is subjected to secondary devolatilization in the double-shaft stirrer 5 to obtain a polysiloxane with low volatile content. Specifically, the polysiloxane after the preliminary devolatilization is introduced into the double-shaft stirrer 5, and subjected to secondary devolatilization in the barrel section provided with an exhaust chamber under vacuum to obtain a polysiloxane with low volatile content.

[0030] As Figure 1 A polysiloxane devolatilization system using the above double-shaft stirrer 5, which provides a devolatilization system and method suitable for polysiloxanes with various viscosities, can efficiently remove volatile components from polysiloxanes, and comprises a first preheater 1, a flash evaporator 2, a first gear pump 3, a second preheater 4, a double-shaft stirrer 5, a second gear pump 6 and a condenser 7 connected in order.

[0031] The flash evaporator 2 is a falling rod devolatilizer, and in some embodiments, a wiped-film evaporator or a short-path distillation device can also be used.

[0032] The devolatilization port of the flash evaporator 2 is one.

[0033] The devolatilization port of the flash evaporator 2 is connected to the first vacuum pumping unit 8.

[0034] A devolatilization method using the above polysiloxane devolatilization system, comprising the following steps:

[0035] A) subjecting the polysiloxane to preliminary devolatilization in the flash evaporator 2 to obtain polysiloxane after preliminary devolatilization;

[0036] B) the polysiloxane after the initial devolatilization is subjected to secondary devolatilization in the double-shaft stirrer 5 to obtain a low-volatile polysiloxane.

[0037] The polysiloxane structure is X(MeRSiO) m (Me2SiO) n Me2SiX, wherein X is one of methyl, vinyl, and hydroxyl, R is one or two of methyl, phenyl, trifluoropropyl, and vinyl, 10000≥m+n≥1000, m≥0, and n≥0. The initial volatile content of the polysiloxane is 10-20%. Specifically, the initial volatile content of the polysiloxane is 10%, 15%, or 20%.

[0038] In the embodiments of the present application, the temperature of the initial devolatilization of the polysiloxane is 170-190°C, the absolute pressure of the initial devolatilization is 200-600 Pa, and the time of the initial devolatilization is 0.5-1 min. Specifically, the temperature of the initial devolatilization is 170°C, 180°C, or 190°C; the absolute pressure of the initial devolatilization is 200 Pa, 400 Pa, or 600 Pa; and the time of the initial devolatilization is 0.5 min, 0.6 min, or 1 min.

[0039] The polysiloxane after the initial devolatilization is subjected to secondary devolatilization in the double-shaft stirrer 5 to obtain a low-volatile polysiloxane. Specifically, the polysiloxane after the initial devolatilization enters the double-shaft stirrer 5, is subjected to secondary devolatilization under vacuum through the barrel segments provided with the devolatilization chambers 5-7-1, 5-7-2, and 5-7-3, and a low-volatile polysiloxane is obtained.

[0040] In the embodiments of the present application, the temperature of the secondary devolatilization is 180-220°C, and the absolute pressure of the secondary devolatilization is 20-100 Pa. Specifically, the temperature of the secondary devolatilization is 180°C, 200°C, and 220°C; and the absolute pressure of the secondary devolatilization is 20 Pa, 60 Pa, or 100 Pa.

[0041] In some embodiments of the present application, the rotation speed of the double-shaft stirrer 5 is 10-50 rpm, and the time of the secondary devolatilization is 1-3 h. Specifically, the rotation speed of the double-shaft stirrer 5 is 10 rpm, 20 rpm, or 50 rpm, and the time of the secondary devolatilization is 1 h, 2 h, or 3 h.

[0042] In some embodiments of the present application, if multiple devolatilization chambers 5-7-1, 5-7-2, and 5-7-3 are used simultaneously in the double-shaft stirrer 5, the temperatures of the corresponding barrels 5-1 of the multiple devolatilization chambers 5-7-1, 5-7-2, and 5-7-3 are the same, and the vacuum degrees of the devolatilization chambers 5-7-1, 5-7-2, and 5-7-3 are the same.

[0043] In some embodiments of the present application, the method for removing volatile components from the polysiloxane, the processing capacity of the polysiloxane is 50-150 kg / h.

[0044] The polysiloxane is preheated and then enters the flash evaporator 2 from the feed inlet of the flash evaporator 2. The first removal of volatile components is performed under vacuum conditions in the flash evaporator 2. The polysiloxane after the first removal of volatile components is discharged from the discharge outlet of the flash evaporator 2, pumped into the preheater 4 through the first gear pump 3, preheated to the required temperature, and then enters the double-shaft agitator 5. The second removal of volatile components is performed under vacuum conditions in the double-shaft agitator 5. The polysiloxane after the second removal of volatile components is pumped into the condenser 7 through the second gear pump 6 for cooling, to obtain the ultra-low volatile polysiloxane. The removal time of volatile components reaches the level of hours, the volatile components are reduced to less than 0.1 wt%, and the individual content of D4, D5, and D6 is reduced to less than 50 ppm. Further, the volatile components can be reduced to less than 0.05 wt%, and the individual content of D4, D5, and D6 can even be less than 20 ppm.

[0045] Example 1

[0046] The present embodiment provides a system for removing volatile components from a vinyl silicone oil as shown in Figure 1 The system comprises:

[0047] The flash evaporator 2 is a scraped film evaporator.

[0048] The feed inlet of the scraped film evaporator 2 is connected to the outlet of the first preheater 1.

[0049] The volatile component removal outlet of the scraped film evaporator 2 is connected to the first vacuum pumping unit 8.

[0050] The discharge outlet of the scraped film evaporator 2 is connected to the inlet of the first gear pump 3 and the inlet of the second preheater 4. The discharge outlet of the second preheater 4 is connected to the inlet of the double-shaft agitator 5.

[0051] The scraped film evaporator 2 is provided with one volatile component removal outlet.

[0052] The double-shaft agitator 5 is a double-shaft self-cleaning low-removal device, comprising:

[0053] A cylinder 5-1.

[0054] The number of volatile component removal chambers provided on the double-shaft agitator 5 is three, which are 5-7-1, 5-7-2, and 5-7-3.

[0055] The exhaust outlets of the volatile component removal chambers 5-7-1, 5-7-2, and 5-7-3 are connected to the second vacuum pumping unit 9.

[0056] The discharge screw 5-10 of the double-shaft agitator 5 is connected to the feed inlet of the second gear pump 6. The discharge outlet of the second gear pump 6 is connected to the inlet of the condenser 7.

[0057] The crude vinyl silicone oil in Example 1 has a structure of Vi(Me2SiO). 800-1000 Me2SiVi, volatile matter content ~15%, devolatilization treatment capacity ~100 kg / h (viscosity 10,000-20,000).

[0058] Specific process flow:

[0059] The crude vinyl silicone oil is preheated to ~180°C in the first preheater 1 and then enters the scraped thin film evaporator 2. The volatiles after devaporization are discharged from the devaporization port. The initial devaporization temperature is ~180°C, the vacuum pressure is ~400 Pa, and the average residence time is ~0.5 min.

[0060] After initial devolatilization, the vinyl silicone oil is preheated to ~200°C and then enters through the material inlet 5-9. The first stirring shafts 5-3-1 and 5-3-2 rotate within the cylinder 5-1 (at a speed of ~20 rpm), propelling the vinyl silicone oil forward. The forward-propelled vinyl silicone oil passes through the cylinder section equipped with devolatilization chambers 5-7-1, 5-7-2, and 5-7-3, undergoing secondary devolatilization under vacuum conditions. The volatiles are discharged through the exhaust ports of the devolatilization chambers. The temperature of the cylinder sections corresponding to devolatilization chambers 5-7-1, 5-7-2, and 5-7-3 is ~200°C, the vacuum absolute pressure of devolatilization chambers 5-7-1, 5-7-2, and 5-7-3 is ~60 Pa, and the average residence time for enhanced devolatilization is ~2 hours. After secondary devolatilization, the vinyl silicone oil is pumped through the discharge screw 5-10 and the second gear pump 6 into the condenser 7 for cooling, yielding ultra-low volatility vinyl silicone oil.

[0061] According to the volatile matter testing standard GBT28610-2012, the volatile matter content of the vinyl silicone oil after volatile matter removal was tested. The results showed that the volatile matter content in the vinyl silicone oil obtained in Example 1 was 0.06 wt%. The contents of D4, D5, and D6 in the obtained vinyl silicone oil were detected by GC headspace analysis. The results showed that the total content of D4, D5, and D6 in the obtained vinyl silicone oil was 39 ppm.

[0062] Example 2

[0063] This embodiment provides a method such as Figure 1 The system shown for removing volatiles from polyvinyl silicone oil includes:

[0064] Flash evaporator 2 is a scraped-plate short-path distillation unit;

[0065] The feed inlet of the scraper-type short-path distillation 2 is connected to the outlet of the first preheater 1;

[0066] The volatilization port of the scraper-type short-path distillation 2 is connected to the first vacuum unit 8;

[0067] The discharge port of the wiped short path distillation 2 is connected to the inlet of the first gear pump 3 and the inlet of the second preheater 4, and the discharge port of the preheater is connected to the inlet of the double-shaft agitator 5.

[0068] The wiped short path distillation 2 is provided with one devolatilization port.

[0069] The double-shaft agitator 5 is a double-shaft self-cleaning low-removal device, comprising:

[0070] The barrel 5-1;

[0071] The number of devolatilization chambers provided on the double-shaft agitator 5 is two, which are 5-7-1 and 5-7-2.

[0072] The exhaust ports of the devolatilization chambers 5-7-1 and 5-7-2 are connected to the second vacuum pumping unit 9.

[0073] The discharge screw 5-10 of the double-shaft agitator 5 is connected to the feeding inlet of the second gear pump 6, and the discharge port of the second gear pump 6 is connected to the inlet of the condenser 7.

[0074] The structure of the crude multi-vinyl silicone oil in Example 2 is Vi(MeViSiO) 5-20 (Me2SiO) 1800-2000 Me2SiVi, the volatile content is about 10%, and the devolatilization treatment amount is about 50 kg / h. (10 million viscosity)

[0075] The specific process flow is as follows:

[0076] The crude multi-vinyl silicone oil is preheated to about 170°C by the first preheater 1, enters the wiped short path distillation 2, and the volatiles after devolatilization are discharged from the devolatilization port. The temperature of the preliminary devolatilization is about 170°C, the vacuum absolute pressure is about 200 Pa, and the average residence time is about 0.5 min.

[0077] After the preliminary devolatilization, the multi-vinyl silicone oil is preheated to about 180°C again, enters from the material feeding port 5-9, the first stirring shaft 5-3-1 and the first stirring shaft 5-3-2 rotate in the barrel 5-1 (the rotating speed is about 10 rpm), and the multi-vinyl silicone oil is pushed forward. The multi-vinyl silicone oil pushed forward is subjected to secondary devolatilization under vacuum conditions in the barrel section provided with the devolatilization chambers 5-7-1 and 5-7-2, and the volatiles are discharged through the exhaust ports of the devolatilization chambers 5-7-1 and 5-7-2. The temperature of the barrel section corresponding to the devolatilization chambers 5-7-1 and 5-7-2 is about 180°C, the vacuum absolute pressure of the devolatilization chambers 5-7-1 and 5-7-2 is about 20 Pa, and the average residence time of the intensified devolatilization is about 3 h. After the secondary devolatilization, the multi-vinyl silicone oil is pumped into the condenser 7 through the discharge screw 5-10, the second gear pump 6, and the second gear pump 6, and after being cooled, the ultra-low volatile vinyl silicone oil is obtained.

[0078] The volatile matter test standard GBT28610-2012 was used to detect the volatile matter of the polyvinyl silicone oil, and the results showed that the volatile matter content of the polyvinyl silicone oil obtained in Example 2 was 0.08wt%. The contents of D4, D5 and D6 in the polyvinyl silicone oil obtained by GC headspace method were detected, and the results showed that the total content of D4, D5 and D6 in the polyvinyl silicone oil obtained was 92ppm.

[0079] Example 3

[0080] The embodiment provides a volatile matter removal system for methyl silicone oil as shown in the figure, which comprises: Figure 1

[0081] The flash evaporator 2 is a falling rod evaporator.

[0082] The feed inlet of the falling rod evaporator 2 is connected with the outlet of the first preheater 1.

[0083] The devolatilization port of the falling rod evaporator 2 is connected with the first vacuum pumping unit 8.

[0084] The discharge port of the falling rod evaporator 2 is connected with the inlet of the first gear pump 3 and the inlet of the second preheater 4, and the discharge port of the second preheater 4 is connected with the inlet of the double-shaft agitator 5.

[0085] The falling rod evaporator 2 is provided with one devolatilization port.

[0086] The double-shaft agitator 5 is a double-shaft self-cleaning low-removal device, which comprises:

[0087] The barrel 5-1;

[0088] The number of devolatilization chambers arranged on the double-shaft agitator 5 is three, which are 5-7-1, 5-7-2 and 5-7-3.

[0089] The exhaust ports of the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 are connected with the second vacuum pumping unit 9.

[0090] The discharge screw rod 5-10 of the double-shaft agitator 5 is connected with the feed inlet of the second gear pump 6, and the discharge port of the second gear pump 6 is connected with the inlet of the condenser 7.

[0091] The structure of the crude methyl silicone oil in Example 3 is Me(Me2SiO) 2500-3000 Me2SiMe, the volatile matter content is about 15%, and the devolatilization treatment capacity is about 150kg / h. (33 million viscosity)

[0092] The specific process flow is as follows:

[0093] ​The crude methyl silicone oil is preheated to about 190 DEG C by the first preheater 1, and then enters the falling-film evaporator 2. The volatile components are discharged from the devolatilization port. The temperature of the preliminary devolatilization is about 190 DEG C, the vacuum pressure is about 600 Pa, and the average residence time is about 1 min.

[0094] The methyl silicone oil after the preliminary devolatilization is preheated to about 220 DEG C again, and then enters the double-shaft agitator 5 through the material feeding port 5-9. The first stirring shaft 5-3-1 and the second stirring shaft 5-3-2 rotate in the cylinder 5-1 (at a speed of about 30 rpm) and push the methyl silicone oil forward. The methyl silicone oil pushed forward is subjected to secondary devolatilization under vacuum in the cylinder segments provided with the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3. The volatile components are discharged from the exhaust ports of the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3. The temperature of the cylinder segments corresponding to the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 is about 220 DEG C, the vacuum pressure of the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 is about 100 Pa, and the average residence time of the intensive devolatilization is about 1 h. The methyl silicone oil after the secondary devolatilization is pumped into the condenser 7 through the discharge screw 5-10 and the second gear pump 6, and then cooled to obtain ultra-low volatile methyl silicone oil.

[0095] The volatile methyl silicone oil is detected according to the volatile component test standard GBT28610-2012. The results show that the volatile component content of the methyl silicone oil obtained in Example 3 is 0.07 wt%. The contents of D4, D5 and D6 in the methyl silicone oil are detected by the GC headspace method. The results show that the total content of D4, D5 and D6 in the obtained methyl silicone oil is 78 ppm.

[0096] Example 4

[0097] The embodiment provides a volatile component removal system for a hydroxyl silicone oil as shown in the accompanying drawings. Figure 1 The embodiment provides a volatile component removal system for a hydroxyl silicone oil as shown in the accompanying drawings.

[0098] The flash evaporator 2 is a scraped-film evaporator.

[0099] The feeding port of the scraped-film evaporator 2 is connected with the outlet of the first preheater 1.

[0100] The devolatilization port of the scraped-film evaporator 2 is connected with the first vacuum pumping unit 8.

[0101] The discharge port of the scraped-film evaporator 2 is connected with the inlet of the second preheater 4 through the first gear pump 3, and the discharge port of the second preheater 4 is connected with the inlet of the double-shaft agitator 5.

[0102] The scraped-film evaporator 2 is provided with one devolatilization port.

[0103] The double-shaft agitator 5 is a double-shaft self-cleaning low-boiling component remover, which comprises:

[0104] cylinder 5-1;

[0105] The number of devolatilization chambers arranged on the double-shaft agitator 5 is 3, which are 5-7-1, 5-7-2 and 5-7-3 respectively.

[0106] The exhaust ports of the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 are connected with the second vacuum unit 9.

[0107] The discharge screw 5-10 of the double-shaft agitator 5 is connected with the feeding inlet of the second gear pump 6, and the discharge outlet of the second gear pump 6 is connected with the inlet of the condenser 7.

[0108] The structure of the crude hydroxyl silicone oil in Example 4 is HO(Me2SiO) 1800-2000 Me2SiOH, the volatile content is about 15%, and the devolatilization treatment amount is about 150 kg / h. (80,000 viscosity)

[0109] Specific process flow:

[0110] The crude hydroxyl silicone oil is preheated to about 190°C by the first preheater 1, enters the scraped film evaporator 2, and the volatiles after devolatilization are discharged from the devolatilization port. The temperature of the preliminary devolatilization is about 190°C, the vacuum absolute pressure is about 600 Pa, and the average residence time is about 0.5 min.

[0111] After the hydroxyl silicone oil after preliminary devolatilization is preheated to about 200°C again, it enters from the material feeding port 5-9, the first stirring shaft 5-3-1 and the first stirring shaft 5-3-2 rotate in the cylinder 5-1 (the rotating speed is 20 rpm) and push the hydroxyl silicone oil forward, the forward pushed hydroxyl silicone oil passes through the cylinder segment provided with the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3, and is subjected to secondary devolatilization under vacuum conditions. The volatiles are discharged through the exhaust ports of the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3. The temperature of the cylinder segment corresponding to the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 is about 200°C, the vacuum absolute pressure of the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 is about 100 Pa, and the time for intensive devolatilization is 1 h. After the secondary devolatilization, the hydroxyl silicone oil is pumped into the condenser 7 through the discharge screw 5-10, the second gear pump 6, and after being cooled, the ultra-low volatile hydroxyl silicone oil is obtained.

[0112] According to the volatile content test standard GBT28610-2012, the hydroxyl silicone oil after devolatilization is detected, and the results show that the volatile content of the hydroxyl silicone oil obtained in Example 4 is 0.08wt%. The contents of D4, D5 and D6 in the hydroxyl silicone oil are detected by GC headspace method, and the results show that the total content of D4, D5 and D6 in the obtained hydroxyl silicone oil is 89 ppm.

[0113] Example 5

[0114] The embodiment provides a volatile component removal system for a phenyl silicone oil as shown in the figure, comprising: Figure 1

[0115] The flash evaporator 2 is a short path distillation.

[0116] The feed inlet of the short path distillation 2 is connected with the outlet of the first preheater 1.

[0117] The devolatilization outlet of the short path distillation 2 is connected with the first vacuum unit 8.

[0118] The outlet of the short path distillation 2 is connected with the inlet of the first gear pump 3 and the second preheater 4, and the outlet of the second preheater 4 is connected with the inlet of the double-shaft agitator 5.

[0119] The short path distillation 2 is provided with one devolatilization outlet.

[0120] The double-shaft agitator 5 is a double-shaft self-cleaning low-removal device, comprising:

[0121] The barrel 5-1.

[0122] The number of devolatilization chambers arranged on the double-shaft agitator 5 is three, which are 5-7-1, 5-7-2 and 5-7-3.

[0123] The exhaust outlets of the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 are connected with the second vacuum unit 9.

[0124] The outlet screw rod 5-10 of the double-shaft agitator 5 is connected with the feed inlet of the second gear pump 6, and the outlet of the second gear pump 6 is connected with the inlet of the condenser 7.

[0125] The structure of the crude phenyl silicone oil in the embodiment 5 is Me(MePhSiO) 80-100 (Me2SiO) 800-1000 Me2SiMe, the volatile component content is about 15%, and the devolatilization treatment capacity is about 100 kg / h.

[0126] The specific process flow is as follows:

[0127] The crude phenyl silicone oil is preheated to about 190 DEG C through the first preheater 1 and then enters the scraped blade short path distillation 2, the volatile components after devolatilization are discharged from the devolatilization outlet, the temperature of the preliminary devolatilization is about 190 DEG C, the vacuum absolute pressure is about 200 pa, and the average residence time is about 0.5 min.

[0128] ​The phenyl silicone oil after the preliminary devolatilization is preheated again to about 220°C, and then is fed into the material feeding port 5-9, and the first stirring shaft 5-3-1 and the first stirring shaft 5-3-2 rotate in the cylinder 5-1 (at a speed of about 20 rpm) and push the phenyl silicone oil forward, and the forwardly pushed phenyl silicone oil passes through the cylinder segments provided with the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3, and is subjected to secondary devolatilization under vacuum, and the volatile components are discharged from the exhaust ports of the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3. The temperature of the cylinder segments corresponding to the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 is about 220°C, the vacuum absolute pressure of the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 is about 20 Pa, and the time for the intensified devolatilization is about 2 h. After the secondary devolatilization, the phenyl silicone oil is pumped into the condenser 7 through the discharge screw 5-10 and the second gear pump 6, and is cooled to obtain ultra-low volatile phenyl silicone oil.

[0129] The phenyl silicone oil after the removal of the volatile components is detected according to the volatile component test standard GBT28610-2012, and the results show that the content of the volatile components in the phenyl silicone oil obtained in Example 5 is 0.06 wt%. The contents of D4, D5 and D6 in the phenyl silicone oil are detected by the GC headspace method, and the results show that the total content of D4, D5 and D6 in the obtained phenyl silicone oil is 56 ppm.

[0130] Example 6

[0131] The present embodiment provides a system for removing volatile components from a methyl vinyl silicone rubber, as shown in Figure 1 The system comprises:

[0132] The flash evaporator 2 is a falling bar evaporator.

[0133] The feeding port of the falling bar evaporator 2 is connected with the outlet of the first preheater 1.

[0134] The devolatilization port of the falling bar evaporator 2 is connected with the first vacuumizing unit 8.

[0135] The discharge port of the falling bar evaporator 2 is connected with the inlet of the second preheater 4 through the first gear pump 3, and the discharge port of the second preheater 4 is connected with the inlet of the double-shaft stirrer 5.

[0136] The falling bar evaporator 2 is provided with one devolatilization port.

[0137] The double-shaft stirrer 5 is a double-shaft self-cleaning low devolatilizer, comprising:

[0138] The cylinder 5-1.

[0139] The number of the devolatilization chambers provided on the double-shaft stirrer 5 is three, which are 5-7-1, 5-7-2 and 5-7-3.

[0140] The exhaust ports of the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 are connected to the second vacuum unit 9.

[0141] The discharge screw 5-10 of the double-shaft agitator 5 is connected to the feed inlet of the second gear pump 6, and the discharge outlet of the second gear pump 6 is connected to the inlet of the condenser 7.

[0142] The crude methyl vinyl silicone rubber in Example 6 is composed of Me(MeViSiO) 200-500 (Me2SiO) 7500- 8000 Me2SiMe, the volatile content is about 15%, and the devolatilization treatment amount is about 50 kg / h.

[0143] The specific process flow is as follows:

[0144] The crude methyl vinyl silicone rubber is preheated to about 180°C by the first preheater 1 and then enters the strip evaporator 2. The volatiles after devolatilization are discharged from the devolatilization port. The temperature of the preliminary devolatilization is 180°C, the vacuum absolute pressure is about 200 Pa, and the average residence time is about 0.5 min.

[0145] After the preliminary devolatilization, the methyl vinyl silicone rubber is preheated to 190°C again and then enters from the material feed inlet 5-9. The first stirring shaft 5-3-1 and the first stirring shaft 5-3-2 rotate in the cylinder 5-1 (at a speed of about 10 rpm) and push the methyl vinyl silicone rubber forward. The methyl vinyl silicone rubber that is pushed forward is subjected to secondary devolatilization under vacuum conditions in the cylinder segments provided with the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3. The volatiles are discharged from the exhaust ports of the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3. The temperature of the cylinder segments corresponding to the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 is about 190°C, the vacuum absolute pressure of the devolatilization chambers 5-7-1, 5-7-2 and 5-7-3 is about 20 Pa, and the time for intensive devolatilization is 3 h. After the secondary devolatilization, the methyl vinyl silicone rubber is pumped into the condenser 7 through the discharge screw 5-10, the second gear pump 6, and the pump to obtain ultra-low volatile methyl vinyl silicone rubber after cooling.

[0146] According to the volatile test standard GBT28610-2012, the methyl vinyl silicone rubber after devolatilization is detected. The results show that the volatile content of the methyl vinyl silicone rubber obtained in Example 6 is 0.07 wt%. The contents of D4, D5 and D6 in the methyl vinyl silicone rubber are detected by GC headspace method. The results show that the total content of D4, D5 and D6 in the obtained methyl vinyl silicone rubber is 38 ppm.

[0147] Comparative Example 1

[0148] The equipment flash evaporator 2 of the present comparative example is a wiped film evaporator, and the low-temperature remover 5 is a wiped short-path evaporator. The process conditions are controlled as in Case 1.

[0149] The structure of the crude vinyl silicone oil in Comparative Example 1 is Vi(Me2SiO) 800-1000 Me2SiVi, the volatile content is about 15%, and the devolatilization treatment capacity is about 100 kg / h. (1-2 million viscosity)

[0150] The specific process flow is as follows:

[0151] The crude vinyl silicone oil is preheated to about 180°C by the first preheater 1, and then enters the wiped film evaporator 2. The volatiles after devolatilization are discharged from the devolatilization port. The temperature of the primary devolatilization is about 180°C, the vacuum absolute pressure is about 400 pa, and the average residence time is about 0.5 min.

[0152] The vinyl silicone oil after primary devolatilization is preheated to about 200°C again, and then enters the wiped short-path evaporator 5. The volatiles after devolatilization are discharged from the devolatilization port. The temperature of the secondary devolatilization is about 200°C, the vacuum absolute pressure is about 60 pa, and the average residence time is about 0.5 min. The low-volatile vinyl silicone oil is obtained. According to the volatile test standard GBT28610-2012, the volatile-removed vinyl silicone oil is detected. The results show that the volatile content of the vinyl silicone oil obtained in Comparative Example 1 is 0.31 wt%. The contents of D4, D5 and D6 in the vinyl silicone oil are detected by GC headspace method. The results show that the total content of D4, D5 and D6 in the obtained vinyl silicone oil is 530 ppm.

[0153] Comparative Example 2

[0154] The equipment flash evaporator 2 of the present comparative example is a wiped film evaporator, and the low-temperature remover 5 is a wiped short-path evaporator. The process conditions are controlled as in Case 1.

[0155] The structure of the crude methyl vinyl silicone rubber in Comparative Example 2 is Me(MeViSiO) 200-500 (Me2SiO) 7500- 8000 Me2SiMe, the volatile content is about 15%, and the devolatilization treatment capacity is about 50 kg / h.

[0156] The specific process flow is as follows:

[0157] The crude methyl vinyl silicone rubber is preheated to about 180°C by the first preheater 1, and then enters the wiped film evaporator 2. The volatiles after devolatilization are discharged from the devolatilization port. The temperature of the primary devolatilization is about 180°C, the vacuum absolute pressure is about 200 pa, and the average residence time is about 0.5 min.

[0158] The methyl vinyl silicone rubber after the preliminary devolatilization was preheated to 190℃ again and then entered into the twin-screw extruder 5. The volatile components after the devolatilization were discharged from the devolatilization port. The temperature for the secondary devolatilization was about 190℃, the vacuum absolute pressure was about 20 pa, and the average residence time was about 3 min. The low volatile component methyl vinyl silicone rubber was obtained.

[0159] According to the volatile component test standard GBT28610-2012, the methyl vinyl silicone rubber after the removal of the volatile components was detected. The results showed that the volatile component content in the methyl vinyl silicone rubber obtained in the comparative example 2 was 0.36 wt%. The contents of D4, D5 and D6 in the methyl vinyl silicone rubber were detected by the GC headspace method. The results showed that the total content of D4, D5 and D6 in the obtained methyl vinyl silicone rubber was 1690 ppm.

[0160] The above description is only the preferred embodiments of the present application, and does not limit the present application in any form. Although the present application has been disclosed as the above preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any modification, change, equivalent change and modification of the above embodiments, which does not depart from the technical solution of the present application, are still within the scope of the present application.

Claims

1. A twin-shaft stirrer, characterized in that, The device includes two parallel stirring shafts, a first stirring shaft and a second stirring shaft, arranged inside the cylinder. Each stirring shaft is equipped with several stirring components, including a stirring plate and a stirring rod. The stirring plate is fixed on the first stirring shaft and the second stirring shaft. The stirring rod includes a stirring beam and a first vertical rod and a second vertical rod fixed at both ends of the stirring beam. The first vertical rod and the second vertical rod 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 vertical rod and the second vertical rod are located on both sides of the stirring plate. The first vertical rod and the second vertical rod are perpendicular to and point towards the first stirring shaft or the second stirring shaft. End caps are provided 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 material outlet; the cylinder is divided into three sections, A, B, and C, from the material inlet to the discharge screw; the cross-sectional area of ​​the stirring rod decreases sequentially from section A to section B to section C; the gap between the stirring disc and the cylinder increases sequentially from section A to section B to section C, and the gap between the stirring disc and the cylinder in section A is <4mm; The mixing plate in section A is circular, the mixing plate in section B is elliptical, and the mixing plate in section C is a regular polygon. The cylinder also has three devolatilization chambers, each connected to a second vacuum unit.

2. A polysiloxane removal system employing the biaxial stirrer of claim 1, characterized in that, include: The components are connected in sequence: a first preheater, a flash evaporator, a first gear pump, a second preheater, a twin-shaft agitator, a second gear pump, and a condenser.

3. The polysiloxane removal system according to claim 2, characterized in that, The flash evaporator is one of a strip devolatilizer, a scraped thin-film evaporator, or a short-path distillation.

4. The polysiloxane removal system according to claim 2, characterized in that, The flash evaporator has a volatilization port.

5. The polysiloxane removal system according to claim 4, characterized in that, The flash evaporator's devastation port is connected to the first vacuum unit.

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