Method for preparing chlorinated ethylene propylene diene monomer rubber by solvent method

Abstract

The invention provides a method for preparing chlorinated ethylene propylene diene monomer by a solvent method, which comprises the following steps: putting ethylene propylene diene monomer raw materials and chloroform into a reaction kettle, and mixing to prepare an ethylene propylene diene monomer chloroform solution with the mass concentration of 3-5wt%; the method comprises the following steps: adding water and an initiator into an ethylene propylene diene monomer chloroform solution, mixing, and introducing chlorine to carry out chlorination reaction; and after the reaction is finished, carrying out post-treatment on the chlorination reaction liquid to obtain a chlorinated ethylene propylene diene monomer product with the chlorine content of 20-40wt%. According to the process, the water-containing chloroform is successfully used as a chlorine-resistant solvent to replace a carbon tetrachloride solvent in the preparation of the chlorinated ethylene propylene diene monomer by the solvent method, and the process has the advantages of simplicity and convenience in operation, low production cost, greenness, environmental friendliness and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer modification, and particularly relates to a method for preparing chlorinated ethylene-propylene-diene monomer rubber by a water-containing chlorine-resistant mixed solvent method. Background Art

[0002] Chlorinated ethylene-propylene-diene monomer rubber is a chlorine-containing polymer obtained by chlorination modification of ethylene-propylene-diene monomer rubber. Since polar chlorine atoms are introduced into the molecular chain of chlorinated ethylene-propylene-diene monomer rubber, it becomes a new polar polymer. It not only retains many valuable properties inherent in ethylene-propylene-diene monomer rubber but also adds many new characteristics. In particular, its adhesion performance has been significantly improved. It can be used in adhesives, polymer modification, high-performance rubber products, etc.

[0003] Before 2009, the industrial production of chlorinated ethylene-propylene-diene monomer rubber mainly adopted the solvent method process. In this method, ethylene-propylene-diene monomer rubber is completely dissolved in carbon tetrachloride under the conditions of heating and stirring, and then an initiator is added and chlorine gas is introduced to react at 70 - 100 °C. The chlorinated product is obtained through post-treatment steps such as solvent removal and drying to obtain the chlorinated ethylene-propylene-diene monomer rubber product. In addition to the solvent method, the aqueous suspension method evenly disperses powdered ethylene-propylene-diene monomer rubber in water with the help of additives and mechanical action, and then introduces chlorine gas for chlorination reaction. However, since chlorine gas is difficult to penetrate into the interior of ethylene-propylene-diene monomer rubber, the product chlorination is uneven, and there is a problem of poor adhesion performance of the product. Therefore, there are still technical bottlenecks in the aqueous suspension method, and it has not been industrially applied yet.

[0004] The most commonly used solvent in the solvent method is carbon tetrachloride. However, carbon tetrachloride is a substance that destroys the ozone layer. With the gradual implementation of the Montreal Protocol globally, China has prohibited the use of carbon tetrachloride in the production of chlorinated polyolefins by the solvent method since 2009. Currently, there is no ideal alternative solvent suitable for this process. Summary of the Invention

[0005] (I) Object of the Invention The object of the present invention is to provide a method for preparing chlorinated ethylene-propylene-diene monomer rubber by the solvent method. By adding water to chloroform, the two are used as solvents together, which not only inhibits the reaction between chloroform and chlorine gas but also can absorb the by-product hydrogen chloride, successfully replacing traditional carbon tetrachloride, and preparing a chlorinated ethylene-propylene-diene monomer rubber product with a content of 20 - 40 wt%. This method has the advantages of simple operation, low production cost, and more environmental protection.

[0006] (II) Technical Solution To solve the above problems, the present invention provides a method for preparing chlorinated ethylene-propylene-diene monomer rubber by the solvent method, which includes the following steps: 1) Put the ethylene-propylene-diene monomer (EPDM) raw material and chloroform into a reaction kettle, mix them to prepare an EPDM chloroform solution with a mass concentration of 3 - 5%. 2) Add water and an initiator to the EPDM chloroform solution obtained in step 1), mix them, and introduce chlorine gas for chlorination reaction. 3) After the reaction is completed, post-treat the chlorination reaction solution obtained in step 2) to obtain a chlorinated EPDM product with a chlorine content of 20 - 40 wt%.

[0007] Specifically, the mixing in step 1) has the following specific conditions: It is carried out under stirring conditions; The mixing temperature is 50 - 60 °C; The mixing time is 2 - 4 h; The feeding volume of the chloroform is 65 - 75% of the volume of the reaction kettle.

[0008] Under these conditions, it can not only ensure the normal progress of the chlorination reaction to obtain a chlorinated EPDM with a chlorine content of 20 - 40 wt%, but also maximize the production efficiency of the reaction kettle.

[0009] In an optional embodiment, the specific conditions for adding water and an initiator to the EPDM chloroform solution obtained in step 1), mixing them, and introducing chlorine gas for chlorination reaction include: First, add water to the EPDM chloroform solution obtained in step 1), and mix it under stirring conditions for 25 - 35 min; Then add part of the initiator and continue to stir and mix for 10 - 20 min, and the mass of the part of the initiator accounts for 40 - 60% of the total mass of the initiator; After the added initiator is completely dissolved, introduce chlorine gas for chlorination reaction; After reacting for 1 - 1.5 h, add the remaining initiator and continue to react for 1 - 1.5 h.

[0010] In another optional embodiment, the specific conditions for adding water and an initiator to the EPDM chloroform solution obtained in step 1), mixing them, and introducing chlorine gas for chlorination reaction include: First, add water to the EPDM chloroform solution obtained in step 1), and mix it under stirring conditions for 25 - 35 min; Then add the initiator and continue to stir and mix for 10 - 20 min; After the added initiator is completely dissolved, introduce chlorine gas for chlorination reaction for 2 - 3 h.

[0011] Preferably, the mass of the water added in step 2) is 2 - 15% of the mass of the chloroform added in step 1.

[0012] At this amount of water addition, not only can the side reaction of generating carbon tetrachloride be inhibited, and the conversion rate of chloroform be controlled below 2‰, but also a chlorinated ethylene-propylene-diene monomer (EPDM) rubber product with a chlorine content of 20-40 wt% and 15-30% by-product hydrochloric acid can be obtained.

[0013] More preferably, the mass of the water added in step 2) is 5-10% of the mass of the chloroform added in step 1). At this ratio, when the obtained 30 wt% chlorinated EPDM rubber product is applied to the adhesion of EPDM rubber vulcanizate / EPDM rubberized rubber system, the peel strength can reach more than 6.5 kN / m.

[0014] Preferably, the mass of the initiator added in step 2) is 0.5-2.0% of the mass of the EPDM rubber raw material added in step 1).

[0015] More preferably, the mass of the initiator added in step 2) is 0.5-1.0% of the mass of the EPDM rubber raw material added in step 1).

[0016] Specifically, the specific conditions of the chlorination reaction in step 2) include: The chlorine gas is uniformly introduced at a rate of 5-10 kg / h; The total amount of chlorine gas introduced is 0.5-1.35 times the mass of the EPDM rubber raw material; The reaction temperature is 50-60 °C.

[0017] Specifically, the EPDM rubber raw material in step 1) is 5-ethylidene-2-norbornene type EPDM rubber with a molecular weight of 50000-150000 g / mol; The initiator is azobisisobutyronitrile.

[0018] Specifically, the post-treatment in step 3) includes: dehydration concentration and desolvation.

[0019] Dehydration concentration: The chlorinated liquid is heated to a certain temperature to distill out about 70% of the chloroform in it, then fresh chloroform is added to restore the solution volume to the initial volume and then heated to distill out about 70% of the chloroform again. This process is cycled until the chlorinated liquid changes from turbid to transparent, indicating that the hydrochloric acid in it has been removed completely. During the evaporation process, water and hydrogen chloride escape from the chlorinated liquid together with the chloroform vapor. The distilled gas is then condensed to form hydrochloric acid and chloroform. Since hydrochloric acid and chloroform are immiscible, the two can be separated by a simple liquid-liquid separation method. The distilled chloroform can be recycled, and the by-product hydrochloric acid can be used as a by-product; Specifically, the heating temperature of the chlorinated liquid is 65-70 °C; The number of times of adding chloroform in the cycle is 2-3 times.

[0020] Precipitation: The chlorinated ethylene-propylene-diene monomer rubber solution after dehydration and concentration is sent into a twin-screw extrusion devolatilizer to remove the remaining chloroform to obtain the finished product.

[0021] The temperature of the conveying section of the twin-screw extrusion devolatilizer is controlled at 110 - 160 °C; The temperature of the discharging section is controlled at 90 - 100 °C.

[0022] (III) Beneficial effects The above technical solution of the present invention has the following beneficial technical effects: A method for preparing chlorinated ethylene-propylene-diene monomer rubber by a solvent method provided by the present invention, by introducing an appropriate amount of water into the reaction system, not only inhibits the reaction between chloroform and chlorine, making the conversion rate of chloroform not more than 2‰, but also can absorb the by-product hydrogen chloride to obtain by-product hydrochloric acid, realizing the alternative use of chloroform and water as a mixed solvent for carbon tetrachloride, and improving the safety and environmental protection of the process. This method has the characteristics of simple operation, low production cost, and more environmental protection, and has good industrial application prospects. Specific embodiments

[0023] To make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that these descriptions are exemplary and not intended to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0024] The raw materials and reagents used in each embodiment of the present invention are all conventional commercially available products, among which: Ethylene-propylene-diene monomer rubber is purchased from Dow Chemical Company, USA, grade 4725P; Chloroform is purchased from Jiangxi Lihua Chemical Industry Co., Ltd., industrial product with a purity of 99%; The initiator azobisisobutyronitrile is purchased from Liaoning Shuangqi Fine Chemical Industry Co., Ltd., industrial product with a purity of 99%; Water is industrial water with solid impurities removed, that is, conventional tap water.

[0025] Example 1 Charge 22 kg of ethylene propylene diene monomer rubber and 525 kg (350 L) of chloroform into a 500 L enamel reactor, heat up to 50 °C, and dissolve under stirring for 4 h. Then, charge 27 kg (27 L) of water into the reactor, stir for 30 minutes, then add 0.055 kg of azobisisobutyronitrile and stir for 15 minutes. Next, uniformly introduce 11.2 kg of chlorine gas into the reactor for reaction at a chlorine feeding rate of 5 kg / h. After reacting for 1.12 h, add another 0.055 kg of azobisisobutyronitrile and continue reacting for 1.12 h. After the reaction is completed, heat the chlorinated liquid (the common name in the industry for the chlorination reaction liquid) to 65 °C, distill out 368 kg (245 L) of chloroform, then add fresh chloroform to restore the solution volume to 377 L and continue heating to distill out 368 kg (245 L) of chloroform. Repeat this process 2 times. During the evaporation process, water and hydrogen chloride escape from the chlorinated liquid along with the chloroform vapor. Finally, send the remaining chlorinated liquid in the reactor to a screw extruder for devolatilization. The temperature of the conveying section is controlled at 110 - 160 °C; the temperature of the discharging section is controlled at 90 °C. After removing chloroform, a chlorinated ethylene propylene diene monomer rubber product with a chlorine content of 20 wt% is obtained, and the chloroform conversion rate is 1.1‰. The viscosity of a 20 wt% toluene solution of this product is 310 mPa·s. When the adhesive prepared with this product is applied to bond an ethylene propylene diene monomer rubber vulcanizate / ethylene propylene diene monomer rubber vulcanizate system, the peel strength is 3.20 kN / m.

[0026] Example 2 22 kg of ethylene-propylene-diene monomer rubber and 525 kg (350 L) of chloroform were charged into a 500 L enamel reactor, and the temperature was raised to 55 °C and dissolved for 3 h under stirring. Then, 37 kg (37 L) of water was added to the reactor, and after stirring for 30 minutes, 0.11 kg of azobisisobutyronitrile was added and stirred for 15 minutes. Subsequently, 19.1 kg of chlorine gas was uniformly introduced into the reactor for reaction at a chlorine gas feeding rate of 8 kg / h. After reacting for 1.2 h, 0.11 kg of azobisisobutyronitrile was added again, and the reaction continued for 1.2 h. After the reaction was completed, the chlorinated solution was heated to 68 °C, 368 kg (245 L) of chloroform was distilled off, and then fresh chloroform was added to restore the solution volume to 387 L and then heated to distill off 368 kg (245 L) of chloroform again. This process was repeated 3 times. During the evaporation process, water and hydrogen chloride escaped from the chlorinated solution together with the chloroform vapor. Finally, the remaining chlorinated solution in the reactor was sent to a screw extruder for devolatilization. The temperature of the conveying section was controlled at 110 - 160 °C; the temperature of the discharging section was controlled at 95 °C. After removing chloroform, a chlorinated ethylene-propylene-diene monomer rubber product with a chlorine content of 30 wt% was obtained, and the conversion rate of chloroform was 1.6‰. The viscosity of a 20 wt% toluene solution of this product was 250 mPa·s. When the adhesive prepared with this product was applied to bond an ethylene-propylene-diene monomer rubber vulcanizate / ethylene-propylene-diene monomer rubber vulcanizate system, the peel strength was 6.77 kN / m.

[0027] Example 3 Into a 500-L enamel reactor, 22 kg of ethylene propylene diene monomer (EPDM) and 525 kg (350 L) of chloroform were charged. The temperature was raised to 60 °C and dissolved under stirring for 2 h. Then, 53 kg (53 L) of water was added into the reactor. After stirring for 30 minutes, 0.11 kg of azobisisobutyronitrile was added and stirred for 15 minutes. Subsequently, 29.8 kg of chlorine gas was uniformly introduced into the reactor for reaction at a chlorine feeding rate of 10 kg / h. After reacting for 1.5 h, 0.11 kg of azobisisobutyronitrile was added and the reaction continued for 1.5 h. After the reaction ended, the chlorinated solution was heated to 70 °C, and 368 kg (245 L) of chloroform was distilled off. Then, fresh chloroform was added to restore the solution volume to 403 L, and then 368 kg (245 L) of chloroform was distilled off again. This process was repeated 3 times. During the evaporation process, water and hydrogen chloride escaped from the chlorinated solution together with the chloroform vapor. Finally, the remaining chlorinated solution in the reactor was sent to a screw extruder devolatilizer. The temperature of the conveying section was controlled at 110 - 160 °C; the temperature of the discharging section was controlled at 100 °C. After removing chloroform, a chlorinated EPDM product with a chlorine content of 40 wt% was obtained, and the chloroform conversion rate was 1.9‰. The viscosity of a 20 wt% toluene solution of this product was 110 mPa·s. When the adhesive prepared with this product was applied to bond the EPDM vulcanizate / EPDM vulcanizate system, the peel strength was 2.82 kN / m.

[0028] For the preparation methods provided in the embodiments of the present invention, the prepared chlorinated EPDM can be dissolved in a 20 wt% toluene or xylene solution of chlorinated EPDM. The solution is clear and transparent without suspended substances or precipitates, indicating that the product has good solubility and meets the requirements of downstream industries such as adhesives. Moreover, in the preparation process of the examples of the present invention, chloroform can be protected from being chlorinated by chlorine gas to form carbon tetrachloride, improving the environmental friendliness of the process, saving production costs, and can replace carbon tetrachloride for the solvent method to prepare chlorinated EPDM.

[0029] It should be understood that the above specific embodiments of the present invention are only used for exemplary illustration or explanation of the principle of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundary of the appended claims, or equivalent forms of such scope and boundary.

Claims

1. A method for preparing chlorinated ethylene-propylene-diene rubber by a solvent method, characterized in that, It includes the following steps: 1) Put the ethylene propylene diene monomer (EPDM) raw material and chloroform into a reaction kettle, mix them to prepare an EPDM chloroform solution with a mass concentration of 3 - 5 wt%. 2) Add water and an initiator to the EPDM chloroform solution obtained in step 1), mix them, and introduce chlorine gas for chlorination reaction. 3) After the reaction is completed, perform post-treatment on the chlorination reaction solution obtained in step 2) to obtain a chlorinated EPDM product with a chlorine content of 20 - 40 wt%.

2. The method according to claim 1, wherein The mixing described in step 1) specifically includes the following conditions: It is carried out under stirring conditions; The mixing temperature is 50 - 60 °C; The mixing time is 2 - 4 h; The feeding volume of the chloroform is 65 - 75% of the volume of the reaction kettle.

3. The method according to claim 1, characterized in that, The specific conditions for adding water and an initiator to the EPDM chloroform solution obtained in step 1) in step 2), and then introducing chlorine gas for chlorination reaction include: First, add water to the EPDM chloroform solution obtained in step 1), and mix for 25 - 35 min under stirring conditions; Then add part of the initiator, and continue to stir and mix for 10 - 20 min. The mass of the part of the initiator accounts for 40 - 60 wt% of the total mass of the initiator; After the added initiator is completely dissolved, introduce chlorine gas for chlorination reaction; After reacting for 1 - 1.5 h, add the remaining initiator and continue to react for 1 - 1.5 h.

4. The method according to claim 1 or 3, characterized in that, The mass of the water added in step 2) is 2 - 15% of the mass of the chloroform added in step 1.

5. The method according to claim 4, wherein The mass of the water added in step 2) is 5 - 10% of the mass of the chloroform added in step 1.

6. The method according to claim 1 or 3, characterized in that, The mass of the initiator added in step 2) is 0.5 - 2.0% of the mass of the EPDM raw material added in step 1.

7. The method according to claim 6, wherein The mass of the initiator added in step 2) is 0.5 - 1.0% of the mass of the EPDM raw material added in step 1.

8. The method according to claim 1 or 3, characterized in that, The specific conditions for the chlorination reaction in step 2) include: The chlorine gas is introduced at a uniform rate of 5 - 10 kg / h; The total amount of chlorine gas introduced is 0.5 - 1.35 times the mass of the EPDM raw material; The reaction temperature is 50 - 60 °C.

9. The method according to claim 1, characterized in that ； The EPDM raw material in step 1) is 5 - ethylidene - 2 - norbornene - type EPDM with a molecular weight of 50000 - 150000 g / mol; The initiator is azobisisobutyronitrile.

10. The method according to claim 1, wherein The post-treatment in step 3) includes: dehydration concentration and desolvation.