Method for preparing chlorosulfonated polyethylene through supercritical reaction

Abstract

The invention provides a method for preparing chlorosulfonated polyethylene through supercritical reaction, and belongs to the technical field of chlorosulfonated polyethylene preparation. The method comprises the following steps: adding a first initiator and first liquid chlorine into a mixed system containing chlorinated polyethylene and a medium, and carrying out chlorination reaction under supercritical conditions to obtain a chlorinated product; and mixing the chlorination product, liquid sulfur dioxide, a second initiator and second liquid chlorine, and carrying out chlorosulfonation reaction under supercritical conditions to obtain the chlorosulfonated polyethylene. According to the invention, carbon dioxide, liquid nitrogen or hydrogen chloride is adopted as a medium, and chlorination reaction is carried out under the supercritical condition, so that an organic chlorine solvent is prevented from being used in the reaction process; the problems of environmental pollution caused by escape of the organic chlorine solvent and poison to operators caused by volatilization of the residual organic chlorine solvent in the product in the processing and using process can be solved, and the corrosion to equipment is small.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of chlorosulfonated polyethylene, and particularly relates to a method for preparing chlorosulfonated polyethylene by a supercritical reaction. Background Art

[0002] Chlorosulfonated polyethylene (hereinafter referred to as CSM) is a special synthetic rubber obtained by the chlorination and chlorosulfonation reactions of polyethylene. Due to the saturation of its structure and the presence of chlorosulfonyl groups, it has good crosslinkability, and the vulcanized rubber has excellent weather resistance, ozone resistance, oil resistance, chemical resistance, abrasion resistance, radiation resistance, flame retardancy and airtightness, and good color stability. It is widely used in automotive rubber parts, flame retardant wires and cables, roofing waterproofing and rubber dams, anti-corrosion linings for chemical equipment, shoemaking and coatings and other fields.

[0003] There are two production methods for chlorosulfonated polyethylene: the solvent method and the gas-solid phase method. In the gas-solid phase method, chlorine gas and sulfur dioxide are introduced into polyethylene or chlorinated polyethylene in a fluidized bed or a fixed bed for reaction. Since the reaction occurs at the gas-solid interface, there is a phenomenon of uneven chlorosulfonation, and the product performance is inferior to that of the solvent method. Moreover, early scorching is likely to occur during the processing, and its application range is limited. Currently, the solvent method is commonly used in industrial production. The solvent method for preparing chlorosulfonated polyethylene includes the following steps: dissolving polyethylene in carbon tetrachloride, first introducing chlorine gas for reaction, then introducing chlorine gas and sulfur dioxide for reaction to obtain a carbon tetrachloride solution of chlorosulfonated polyethylene, and then separating carbon tetrachloride to obtain CSM. However, this method uses and consumes a large amount of carbon tetrachloride during the production process, which damages the atmospheric ozone layer, and the residual organic chlorine solvent in the product volatilizes during the processing and use, which will be toxic to the operators. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for preparing chlorosulfonated polyethylene by a supercritical reaction. The present invention conducts the chlorination reaction under supercritical conditions, avoiding the use of organic chlorine solvents, and can solve the environmental pollution caused by the escape of organic chlorine solvents and the toxicity of the residual organic chlorine solvents in the product to the operators during the processing and use.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing chlorosulfonated polyethylene by a supercritical reaction, including the following steps:

[0007] Adding a first initiator and first liquid chlorine into a mixed system containing chlorinated polyethylene and a medium, and conducting a chlorination reaction under supercritical conditions to obtain a chlorinated product;

[0008] Mix the chlorinated product, liquid sulfur dioxide, second initiator and second liquid chlorine, and carry out a chlorosulfonation reaction under supercritical conditions to obtain the chlorosulfonated polyethylene.

[0009] Preferably, the medium includes one or more of carbon dioxide, liquid nitrogen and hydrogen chloride.

[0010] Preferably, the pressure of the system obtained after addition is 10 - 20 MPa.

[0011] Preferably, the pressure of the chlorination reaction is ≤35 MPa, the temperature is 60 - 115 °C, and the time is 60 - 120 min.

[0012] Preferably, the pressure of the chlorination reaction is ≤30 MPa, the temperature is 65 - 95 °C, and the time is 70 - 90 min.

[0013] Preferably, the mass ratio of the chlorinated polyethylene, total liquid chlorine and liquid sulfur dioxide is 100:30 - 60:5 - 14. The total liquid chlorine includes first liquid chlorine and second liquid chlorine, and the content of the first liquid chlorine in the total liquid chlorine is 55 - 80 wt%.

[0014] Preferably, the dosages of the first initiator and the second initiator are independently 0.05 - 3 wt% of the chlorinated polyethylene, and the first initiator and the second initiator independently include azo dinitrile initiators and / or peroxide initiators.

[0015] Preferably, the chlorinated polyethylene is in powder form, with a chlorine content of 20 - 32 wt%, a Mooney viscosity of volatile matter <0.5 wt%, and an average particle size <400 μm.

[0016] Preferably, the pressure of the chlorosulfonation reaction is ≤35 MPa, the temperature is 85 - 115 °C, and the time is 70 - 150 min. The time is calculated from the completion of the addition of the reaction raw materials.

[0017] Preferably, the pressure of the chlorosulfonation reaction is ≤30 MPa, the temperature is 95 - 105 °C, and the time is 80 - 120 min.

[0018] The present invention provides a method for preparing chlorosulfonated polyethylene by a supercritical reaction, which includes the following steps: Add a first initiator and first liquid chlorine to a mixed system containing chlorinated polyethylene (CPE) and a medium, and carry out a chlorination reaction under supercritical conditions to obtain a chlorinated product; Mix the chlorinated product, liquid sulfur dioxide, second initiator and second liquid chlorine, and carry out a chlorosulfonation reaction under supercritical conditions to obtain the chlorosulfonated polyethylene.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The present invention uses carbon dioxide, liquid nitrogen and hydrogen chloride as media and conducts a chlorination reaction under supercritical conditions, thereby avoiding the use of organic chlorine solvents during the reaction process. This can solve the environmental pollution caused by the escape of organic chlorine solvents and the toxicity to operators caused by the volatilization of residual organic chlorine solvents in the product during processing and use, and also has little corrosion to equipment. The present invention has the advantages of being suitable for large-scale industrial production, being green and environmentally friendly, having product performance equivalent to that of products obtained by the solvent method, and having stable quality. Specific Embodiments

[0021] The present invention provides a method for preparing chlorosulfonated polyethylene by a supercritical reaction, which includes the following steps:

[0022] Adding a first initiator and first liquid chlorine to a mixed system containing chlorinated polyethylene and a medium, and conducting a chlorination reaction under supercritical conditions to obtain a chlorinated product;

[0023] Mixing the chlorinated product, liquid sulfur dioxide, a second initiator and second liquid chlorine, and conducting a chlorosulfonation reaction under supercritical conditions to obtain the chlorosulfonated polyethylene.

[0024] In the present invention, unless otherwise specified, the raw materials and equipment used are all commercially available products in the art.

[0025] The present invention adds a first initiator and first liquid chlorine to a mixed system containing chlorinated polyethylene and a medium, and conducts a chlorination reaction under supercritical conditions to obtain a chlorinated product.

[0026] In the present invention, the chlorinated polyethylene is preferably in powder form, the chlorine content is preferably 20-32 wt%, specifically it can be 20, 21.8, 22.5, 25.3, 30 or 32 wt%, and the Mooney viscosity is preferably The volatile matter is preferably <0.5 wt%, specifically it can be 0.18 or 0.3 wt%, the average particle size is preferably <400 μm, more preferably <250 μm, specifically it can be 197 or 210 μm; the chlorine content of the chlorinated polyethylene determines the chlorine content of the product, the Mooney viscosity determines the processing performance of the product, the volatile matter mainly refers to water, and water will react with sulfur dioxide to generate sulfuric acid, which is difficult to separate, and if the particle size is too large, it is not easy to dissolve.

[0027] In the present invention, the medium preferably includes one or more of carbon dioxide, liquid nitrogen and hydrogen chloride, more preferably carbon dioxide, and further preferably liquid carbon dioxide.

[0028] In the present invention, the pressure of the system obtained after addition is preferably 10-20 MPa, specifically it can be 10, 12, 14, 16, 18 or 20 MPa. Under this condition, it can not only ensure reaching the supercritical state, but also avoid excessive pressure resulting in increased energy consumption.

[0029] In the present invention, the first initiator preferably includes azo dinitrile initiators and / or peroxide initiators. The azo dinitrile initiators preferably include azodiisooctylonitrile, and the peroxide initiators preferably include acetyl cyclohexylsulfonyl peroxide and / or chloral diperoxide.

[0030] In the present invention, the dosage of the first initiator is preferably 0.05 - 3 wt% of the chlorinated polyethylene, specifically it can be 0.05, 0.08, 0.1, 0.5, 1, 1.5, 2, 2.5 or 3 wt%. The dosage of the first initiator determines the chlorination reaction rate. If the addition amount is too much, the chlorination reaction rate is too fast, and the heat generated by the chlorination reaction makes it difficult to control the temperature.

[0031] In the present invention, the chlorination reaction is preferably carried out in a high-pressure chlorination reactor. The high-pressure chlorination reactor is preferably an autoclave reactor, which preferably consists of a stirrer, an internal heat exchanger, a frame and a transmission system, a sealing system, baffles, a jacket and a cold water circulation cooling system. The design pressure of the autoclave reactor is preferably ≥40 MPa.

[0032] In the present invention, the materials of the reactor body and the inner wall of the autoclave reactor, as well as the stirrer and the baffles, are all preferably corrosion-resistant materials lined with steel, and more preferably fluoroplastics lined with steel.

[0033] In the present invention, the pressure of the chlorination reaction is preferably ≤35 MPa, more preferably ≤30 MPa, the temperature is preferably 60 - 115 °C, more preferably 65 - 95 °C, and the time is preferably 60 - 120 min, more preferably 70 - 90 min. Specifically, it can be 60, 70, 80, 90, 100, 110 or 120 min. The conditions of the chlorination reaction are affected by the type and dosage of the initiator and the heat transfer factor of the chlorination reaction. If the temperature is too low, the reaction does not occur or the reaction rate is slow. If the temperature is too high, the corresponding pressure is high, and the equipment's bearing capacity is limited. The chlorination reaction is a process in which the temperature and pressure change continuously. As the temperature rises, the pressure also gradually rises.

[0034] The present invention preferably adds the chlorinated polyethylene into a high-pressure chlorination reactor, starts the stirring of the reactor, with a rotation speed of 0 to 80 revolutions per minute (preferably 0 to 40 revolutions per minute, more preferably 0 to 20 revolutions per minute, specifically it can be 25 or 15 revolutions per minute), fills the medium until the pressure in the reactor rises to 0.5 to 2 MPa (specifically it can be 0.5, 1 or 2 MPa), then releases the pressure, and repeats the above operations 1 to 3 times to remove the moisture contained in the chlorinated polyethylene and the oxygen in the reactor space. Then, the medium is filled until the pressure in the reactor is 10 to 20 MPa, and then steam is introduced into the internal heat exchanger to heat the material to 60 to 80 °C. The first initiator is added, and the first liquid chlorine is introduced into the reactor with a high-pressure pump until the total chlorine (total liquid chlorine) input reaches 55 to 80 wt% (specifically it can be 55, 60, 65, 70, 75 or 80 wt%), and the chlorination reaction is carried out.

[0035] In the present invention, the feeding flow rate of the first liquid chlorine is preferably 100 to 200 g / min.

[0036] After obtaining the chlorinated product, the present invention mixes the chlorinated product, liquid sulfur dioxide, the second initiator and the second liquid chlorine, and carries out a chlorosulfonation reaction under supercritical conditions to obtain the chlorosulfonated polyethylene.

[0037] In the present invention, the mass ratio of the chlorinated polyethylene, the total liquid chlorine and the liquid sulfur dioxide is preferably 100:30 to 60:4 to 14, more preferably 100:40 to 50:5 to 10, specifically it can be 25:10.8:2.4, 50:24.3:5.6 or 70:26.9:3.9. The total liquid chlorine includes the first liquid chlorine and the second liquid chlorine, and the content of the first liquid chlorine in the total liquid chlorine is preferably 55 to 80 wt%.

[0038] In the present invention, the second initiator preferably includes an azo dinitrile initiator and / or a peroxide initiator. The azo dinitrile initiator preferably includes azodiisooctylonitrile, and the peroxide initiator preferably includes acetyl cyclohexylsulfonyl peroxide and / or chloral diperoxide.

[0039] In the present invention, the dosage of the second initiator is preferably 0.05 to 3 wt% of the chlorinated polyethylene, specifically it can be 0.05, 0.08, 0.1, 0.5, 0.7, 1, 1.5, 2, 2.5 or 3 wt%. The dosage of the second initiator determines the rate of the chlorosulfonation reaction. If the added amount is too much, the rate of the chlorosulfonation reaction is too fast, and the heat generated by the chlorosulfonation reaction makes the temperature difficult to control.

[0040] In the present invention, the mass ratio of the second liquid chlorine to the liquid sulfur dioxide is preferably 1:0.3 to 0.7.

[0041] In the present invention, the pressure of the chlorosulfonation reaction is preferably ≤35 MPa, more preferably ≤30 MPa, the temperature is preferably 85 - 115 °C, more preferably 95 - 105 °C, and the time is preferably 70 - 150 min, more preferably 80 - 120 min. Specifically, it can be 80, 90, 100, 110 or 120 min. The time is calculated from the completion of the addition of the reaction raw materials. The conditions of the chlorosulfonation reaction are affected by the variety and dosage of the initiator and the heat transfer factor of the chlorosulfonation reaction. If the temperature is too low, the reaction does not occur or the reaction rate is slow. If the temperature is too high, the corresponding pressure is high and the equipment's bearing capacity is limited. The chlorosulfonation reaction is a process in which the temperature and pressure change continuously. As the temperature rises, the pressure also gradually increases.

[0042] In the present invention, it is preferred to add the second initiator to the reaction kettle, then introduce liquid sulfur dioxide and second liquid chlorine, introduce cooling water into the built-in cooler, control the reaction temperature to carry out the chlorosulfonation reaction. After the chlorosulfonation reaction is completed, continue to stir for 30 - 60 min, lower the temperature of the obtained material to 45 - 65 °C (specifically, it can be 49 or 53 °C), open the discharge valve at the bottom of the reaction kettle, and discharge the obtained reaction product under reduced pressure to the receiver. After separating and removing hydrogen chloride and chlorine from the gas phase part (the main components include carbon dioxide, hydrogen chloride, chlorine and sulfur dioxide), the solid phase part is collected and then transferred to a purifier, and nitrogen is blown to displace the residual acidic gas to obtain the chlorosulfonated polyethylene.

[0043] In the present invention, the receiver preferably comprises a steel-lined fluoroplastic kettle body, a rotary spray head, a top cyclone separator and two-stage series spray towers. The effective volume of the corrosion-resistant pressure vessel is preferably 10 - 20 times that of the high-pressure chlorination reactor.

[0044] In the present invention, the waste gas outlet of the cyclone separator is preferably connected in series with two-stage spray absorption towers. The spray absorption towers preferably include a hydrogen chloride spray absorption tower and a tail gas spray absorption tower connected in series in sequence. The hydrogen chloride spray absorption tower reacts hydrogen chloride and sulfur dioxide in the gas phase part with water to prepare by-product acid. The residual chlorine and hydrogen chloride in the gas phase part are preferably purified with 5 wt% NaOH in the tail gas spray absorption tower, and the purified tail gas is discharged into the atmosphere.

[0045] In the present invention, after the reaction product is discharged to the receiver under reduced pressure, it is preferably filled with liquid carbon dioxide to a pressure of 10 - 20 MPa, stirred for 10 min, and the pressure is released to the receiver. The above operation is repeated 1 - 3 times, and then the discharge valve is closed. The function of this step is to clean the materials adhering to the reactor wall and the built-in heat exchanger.

[0046] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0047] In the embodiments of the present invention, the test standard for Mooney viscosity is GB / T 1232.1;

[0048] Testing of vulcanizate properties:

[0049] Detection formula (parts by mass): chlorosulfonated polyethylene 100; magnesium oxide 10; carbon black N330 20; carbon black N774 20; trioctyl trimellitate (TOTM, plasticizer) 16; pentaerythritol 3; dipentamethylene thiuram tetrasulfide (DPTT, vulcanization accelerator) 2;

[0050] Vulcanization conditions: 160 °C, 10 min.

[0051] Test the tensile strength and elongation at break of the vulcanizate according to the standard of GB / T 1701-2001.

[0052] Example 1

[0053] A method for preparing chlorosulfonated polyethylene by a supercritical reaction, comprising the following steps:

[0054] (1) Selection; Mooney viscosity Add 25 kg of chlorinated polyethylene powder with a chlorine content of 22.5 wt%, an average particle size of 210 μm, and a volatile content of 0.18 wt% into a high-pressure chlorination reactor (designed pressure 40 MPa, equipped with stirring), start stirring, the rotation speed is 25 revolutions per minute, and seal.

[0055] (2) Add liquid carbon dioxide to the reaction kettle of the high-pressure chlorination reactor, gradually increase the pressure to 1 MPa, release the pressure to 0 MPa after 5 minutes, repeat the above operation once, and then fill with liquid carbon dioxide until the pressure reaches 20 MPa. Pass steam into the built-in heat exchanger to heat the material to 65 °C, and supplement liquid carbon dioxide until the pressure reaches 20 MPa.

[0056] (3) Use the built-in heat exchanger to heat the material to 75 °C, add 180 g of azobisisobutyronitrile, start the high-pressure pump to inject the first liquid chlorine into the reactor, control the flow rate at 100 g / min, make the material temperature rise, control the temperature at 75-94 °C, the pressure < 24 MPa, when the material temperature rises to 94 °C, pass cooling water into the built-in heat exchanger to cool the system, control the temperature at 94-105 °C, the pressure < 29 MPa, until the chlorine feeding amount of the first liquid chlorine reaches 6.9 kg.

[0057] (4) Add 180 g of azobisisobutyronitrile, start the high-pressure pump to inject the second liquid chlorine and liquid sulfur dioxide into the reactor. The reaction temperature is 100 °C, the pressure is 28 MPa. After injecting 3.9 kg of the second liquid chlorine and 2.4 kg of sulfur dioxide, stop injecting chlorine and sulfur dioxide, and continue to cool to 49 °C.

[0058] The total chlorine injection amount is 10.8 kg, and the sulfur dioxide is 2.4 kg.

[0059] (5) Open the discharge bottom valve, control the discharge speed, and discharge the material into the receiver. The gas phase part is dedusted by a cyclone separator and discharged after two-stage spray absorption. The two-stage spray absorption tower successively includes a hydrogen chloride spray absorption tower and a tail gas spray absorption tower. The hydrogen chloride spray absorption tower uses water for absorption, and the tail gas spray absorption tower uses 5 wt% NaOH. The collected solid powder is purified by nitrogen replacement to obtain 29.76 kg of finished product.

[0060] Test results of the product: chlorine content 33.8 wt% (GB / T 9872); sulfur content 1.10 wt% (GB4497); Mooney viscosity Volatile matter 0.21 wt%.

[0061] Mechanical strength of vulcanized rubber: tensile strength 34.6 MPa, elongation at break 312%.

[0062] Example 2

[0063] A method for preparing chlorosulfonated polyethylene by supercritical reaction, comprising the following steps:

[0064] (1) Select; Mooney viscosity Add 50 kg of chlorinated polyethylene powder with a chlorine content of 21.8 wt%, an average particle size of 210 μm, and a volatile matter of 0.18 wt% into a high-pressure chlorination reactor (designed pressure 40 MPa, equipped with stirring). Start stirring, the rotation speed is 15 revolutions per minute, and seal.

[0065] (2) Add liquid carbon dioxide to the reaction kettle of the high-pressure chlorination reactor, gradually increase the pressure to 0.5 MPa, release the pressure to 0 MPa after 5 minutes, repeat the above operation 3 times, and then fill with liquid carbon dioxide until the pressure reaches 15 MPa. Pass steam into the built-in heat exchanger to heat the material to 60 °C, and supplement liquid carbon dioxide until the pressure reaches 15 MPa.

[0066] (3) Use the built-in heat exchanger to heat the material to 60 °C, add 400 g of azobisisobutyronitrile, start the high-pressure pump to inject the first liquid chlorine into the reactor, control the flow rate at 200 g / min, make the material temperature rise, control the temperature at 60 - 94.5 °C, the pressure < 24 MPa. When the material temperature rises to 94.5 °C, pass cooling water into the built-in heat exchanger to cool the system. The chlorine injection amount of the first liquid chlorine is 14.5 kg.

[0067] (4) Add 400 g of azobisisobutyronitrile. Start the high-pressure pump to inject the second liquid chlorine and liquid sulfur dioxide into the reactor. The reaction temperature is 90 °C, the pressure is 28 MPa. After injecting 9.8 kg of the second liquid chlorine and 5.6 kg of sulfur dioxide, stop injecting chlorine and sulfur dioxide, and continue to cool to 53 °C.

[0068] The total amount of injected chlorine is 24.3 kg, and the amount of sulfur dioxide is 5.6 kg.

[0069] (5) Open the discharge bottom valve, control the discharge speed, and discharge the material into the receiver. The gas phase part is dedusted by a cyclone separator and discharged after two-stage spray absorption. The two-stage spray absorption tower sequentially includes a hydrogen chloride spray absorption tower and a tail gas spray absorption tower. The hydrogen chloride spray absorption tower uses water for absorption, and the tail gas spray absorption tower uses 5 wt% NaOH. The collected solid powder is purified by nitrogen displacement to obtain 60.1 kg of the finished product.

[0070] Test results of the product: chlorine content 36.4 wt% (GB / T 9872); sulfur content 1.30 wt% (GB4497); Mooney viscosity Volatile matter 0.2 wt%.

[0071] Mechanical strength of vulcanized rubber: tensile strength 36.1 MPa, elongation at break 367%.

[0072] Example 3

[0073] A method for preparing chlorosulfonated polyethylene by supercritical reaction, comprising the following steps:

[0074] (1) Select; Mooney viscosity Add 70 kg of chlorinated polyethylene powder with a chlorine content of 25.3 wt%, an average particle size of 197 μm, and a volatile matter of 0.3 wt% into a high-pressure chlorination reactor (designed pressure 40 MPa, equipped with stirring). Start the stirring, with a rotation speed of 15 revolutions per minute, and seal it.

[0075] (2) Add liquid carbon dioxide to the reaction kettle of the high-pressure chlorination reactor, gradually increase the pressure to 0.5 MPa, release the pressure to 0 MPa after 5 minutes, repeat the above operation 3 times, and then fill with liquid carbon dioxide until the pressure reaches 13 MPa. Pass steam into the built-in heat exchanger to heat the material to 65 °C, and supplement liquid carbon dioxide until the pressure reaches 13 MPa.

[0076] (3) Use the built-in heat exchanger to heat the material to 60 °C, add 400 g of azobisisobutyronitrile, start the high-pressure pump to inject the first liquid chlorine into the reactor, control the flow rate at 100 g / min, make the material temperature rise, control the temperature at 105 °C, and the pressure < 20 MPa. When the material temperature rises to 105 °C, pass cooling water into the built-in heat exchanger to cool the system. The amount of injected chlorine of the first liquid chlorine is 15 kg.

[0077] (4) Add 400 g of azobisisobutyronitrile, turn on the high-pressure pump to inject second liquid chlorine and liquid sulfur dioxide into the reactor. The reaction temperature is 90 °C, the pressure is 28 MPa. After introducing 11.9 kg of chlorine and 3.9 kg of sulfur dioxide, stop introducing chlorine and sulfur dioxide, and continue to cool to 53 °C.

[0078] The total amount of chlorine introduced is 26.9 kg, and sulfur dioxide is 3.9 kg.

[0079] (5) Open the discharge bottom valve, control the discharge speed, and discharge the material into the receiver. The gas phase part is dust-removed by a cyclone separator and discharged after two-stage spray absorption. The two-stage spray absorption tower sequentially includes a hydrogen chloride spray absorption tower and a tail gas spray absorption tower. The hydrogen chloride spray absorption tower uses water for absorption, and the tail gas spray absorption tower uses 5 wt% NaOH. The collected solid powder is purified by nitrogen displacement to obtain 80.1 kg of finished product.

[0080] Test results of the product: chlorine content 35.7 wt% (GB / T 9872); sulfur content 1.24 wt% (GB4497); Mooney viscosity Volatile matter 0.4 wt%.

[0081] Mechanical strength of vulcanized rubber: tensile strength 37.6 MPa, elongation at break 332%.

[0082] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing chlorosulfonated polyethylene by supercritical reaction, characterized in that, Comprising the following steps: Adding a first initiator and first liquid chlorine into a mixed system containing chlorinated polyethylene and a medium, and carrying out a chlorination reaction under supercritical conditions to obtain a chlorinated product; Mixing the chlorinated product, liquid sulfur dioxide, a second initiator and second liquid chlorine, and carrying out a chlorosulfonation reaction under supercritical conditions to obtain the chlorosulfonated polyethylene.

2. The method according to claim 1, characterized in that The medium includes one or more of carbon dioxide, liquid nitrogen and hydrogen chloride.

3. The method according to claim 1 or 2, characterized in that The pressure of the system obtained after the addition is 10 - 20 MPa.

4. The method according to claim 1, wherein The pressure of the chlorination reaction is ≤ 35 MPa, the temperature is 60 - 115 °C, and the time is 60 - 120 min.

5. The method according to claim 4, wherein The pressure of the chlorination reaction is ≤ 30 MPa, the temperature is 65 - 95 °C, and the time is 70 - 90 min.

6. The method according to claim 1, wherein The mass ratio of the chlorinated polyethylene, total liquid chlorine and liquid sulfur dioxide is 100:30 - 60:4 - 14. The total liquid chlorine includes first liquid chlorine and second liquid chlorine, and the content of the first liquid chlorine in the total liquid chlorine is 55 - 80 wt%.

7. The method according to claim 1, wherein The dosages of the first initiator and the second initiator are independently 0.05 - 3 wt% of the chlorinated polyethylene. The first initiator and the second initiator independently include azo dinitrile initiators and / or peroxide initiators.

8. The method according to claim 1, wherein The chlorinated polyethylene is in powder form, with a chlorine content of 20 to 32 wt%, and a Mooney viscosity of volatile matter < 0.5 wt%, and an average particle size < 400 μm.

9. The method according to claim 1, characterized in that, The pressure of the chlorosulfonation reaction is ≤ 35 MPa, the temperature is 85 - 115 °C, and the time is 70 - 150 min. The time is calculated from the completion of the addition of the reaction raw materials.

10. The method according to claim 9, wherein The pressure of the chlorosulfonation reaction is ≤ 30 MPa, the temperature is 95 - 105 °C, and the time is 80 - 120 min.

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