阅读说明：本技术 一种分步聚合制备液体氯丁橡胶的方法及其制备的液体氯丁橡胶 (Method for preparing liquid chloroprene rubber through step polymerization and liquid chloroprene rubber prepared through method ) 是由 毛利军 郭立平 贾佳 高文龙 李俊 刘慧彬 张淑娟 刘日� 齐中华 魏凯 公冶波 于 2020-06-17 设计创作，主要内容包括：本发明属于氯丁橡胶制备技术领域,提供了一种分步聚合制备液体氯丁橡胶的方法及其制备的液体氯丁橡胶。溶解于甲苯的氯丁二烯单体与分子量调节剂在氮气保护下升温,加入油溶性引发剂引发反应制备得到活性种,将得到的活性种作为二次聚合反应的引发剂,加入到溶解于甲苯的氯丁二烯单体溶液、分子量调节剂反应体系中,继续聚合反应,反应结束后添加终止剂终止反应,即得液体氯丁橡胶。通过改变反应所用调节剂与引发剂的量可以得到不同粘度的液体氯丁橡胶,作为活性种又可以制得不同粘度的最终产物。对工艺操作简单,聚合周期短,转化率高,生产成本低。制备的液体氯丁橡胶颜色浅,环保性好,利于工业化应用。制备过程更加高效,产品更符合环保要求。(The invention belongs to the technical field of chloroprene rubber preparation, and provides a method for preparing liquid chloroprene rubber by step polymerization and the prepared liquid chloroprene rubber. Heating the chloroprene monomer dissolved in toluene and a molecular weight regulator under the protection of nitrogen, adding an oil-soluble initiator to initiate reaction to prepare active species, taking the obtained active species as an initiator of secondary polymerization reaction, adding the initiator into a reaction system of the chloroprene monomer solution dissolved in toluene and the molecular weight regulator, continuing the polymerization reaction, and adding a terminator to terminate the reaction after the reaction is finished, thus obtaining the liquid chloroprene rubber. Liquid chloroprene rubber with different viscosities can be obtained by changing the amount of the regulator and the initiator used in the reaction, and the liquid chloroprene rubber can be used as an active species to prepare final products with different viscosities. Simple technological operation, short polymerization period, high conversion rate and low production cost. The prepared liquid chloroprene rubber has light color and good environmental protection property, and is beneficial to industrial application. The preparation process is more efficient, and the product meets the environmental protection requirement.)

1. A method for preparing liquid chloroprene rubber by step polymerization is characterized by comprising the following steps: heating the chloroprene monomer dissolved in toluene and a molecular weight regulator under the protection of nitrogen, adding an oil-soluble initiator to initiate reaction to prepare active species, taking the obtained active species as an initiator of secondary polymerization reaction, adding the initiator into a reaction system of the chloroprene monomer solution dissolved in toluene and the molecular weight regulator, continuing the polymerization reaction, and adding a terminator to terminate the reaction after the reaction is finished, thus obtaining the liquid chloroprene rubber.

2. The method for preparing liquid chloroprene rubber by step polymerization according to claim 1, characterized in that: in the preparation system of the active species: 100 parts by weight of 2-chloro-1, 3-butadiene monomer is dissolved in 80 parts by weight of toluene, 20 to 80 parts by weight of molecular weight regulator is added, and 0.2 to 0.8 part by weight of initiator is added after dissolution for reaction.

3. The method for preparing liquid chloroprene rubber by step polymerization according to claim 1, characterized in that: in the system of the secondary polymerization reaction: dissolving 1000 parts by weight of chloroprene monomer in 800 parts by weight of toluene, adding 60-150 parts by weight of molecular weight regulator, adding 50 parts by weight of active species after dissolving, and adding 0.5-1 part by weight of terminator after reaction.

4. A process for the stepwise polymerization of liquid neoprene according to any one of claims 1-3, wherein: the molecular weight regulator is any one of diisopropyl disulfide orthoester, dodecyl mercaptan or thioglycolic acid; the oil-soluble initiator is cumene hydroperoxide, dibenzoyl peroxide or azobisisobutyronitrile; the terminator is any one of antioxidant TBC, antioxidant 264, antioxidant 1010 or antioxidant 168.

5. A process for the stepwise polymerization of liquid neoprene according to any one of claims 1-3, wherein: the method comprises the following specific steps:

(1) preparing reactive species: uniformly mixing chloroprene monomers and toluene in proportion, adding a molecular weight regulator into the mixed solution, fully stirring and dissolving, heating to 45-55 ℃ under the protection of nitrogen, adding an initiator, and reacting for 38-48h to obtain active species;

2) and preparing liquid chloroprene rubber: uniformly mixing chloroprene monomers and toluene, adding a molecular weight regulator, fully stirring and dissolving, heating to 45-55 ℃ under the protection of nitrogen, adding the prepared active species, reacting for 3-8 hours, adding a terminator into the system, and terminating the reaction;

3) and (3) product treatment: after the reaction is ended, the reaction solution is decompressed and concentrated at room temperature, the temperature is increased to 75 ℃ until no bubbles are generated, simultaneously, no methylbenzene is generated at a condenser, and the precipitated product is repeatedly washed by methanol or ethanol for 3-5 times to obtain the liquid chloroprene rubber.

6. The method of making liquid neoprene according to claim 5, wherein: in the step (1), the reaction temperature is 55 ℃, and the reaction time is 48 hours; in the step (2), the reaction temperature is 55 ℃, and the reaction time is 8 h.

7. A liquid neoprene rubber prepared by the method of any one of claims 1 to 3.

Technical Field

The invention belongs to the technical field of chloroprene rubber preparation, and particularly relates to a method for preparing liquid chloroprene rubber by step polymerization and the prepared liquid chloroprene rubber.

Background

At present, most of products applied to the chloroprene rubber market are solid chloroprene rubber, and the application field of liquid chloroprene rubber is small.

The solid chloroprene rubber has higher energy consumption in the production process, more pollutants are generated along with the solid chloroprene rubber, the processing process is complicated, the factors limit the further development of the solid chloroprene rubber, and a larger development space is left for the liquid chloroprene rubber.

Solid chloroprene rubber is required to be a product required in production and life, and a plurality of processes such as mixing with various auxiliary agents and compounding agents, molding, vulcanization and the like are required, while liquid chloroprene rubber can be prepared by blending various other required raw materials and carrying out a crosslinking reaction by heating. The liquid chloroprene rubber has the advantages of easy processing and low energy consumption. It is still in liquid state after being mixed with various raw materials, and when it is used for making small-sized components and parts, it can be solidified after being injected into small gap, so that it is very convenient in processing operation. Liquid neoprene, despite these advantages, is detrimental to production technology, among other factors, such as: initiation is difficult, no ideal initiator is available; the reaction period is longer than that of emulsion polymerization used for solid chloroprene rubber; the product viscosity is unstable; poor appearance and color. The development of which is limited by various technical reasons, the field of application is currently small compared to other liquid rubbers.

Disclosure of Invention

The invention aims to solve the problems of the existing liquid chloroprene rubber, and provides a method for preparing the liquid chloroprene rubber by step polymerization and the prepared liquid chloroprene rubber. The characteristics increase the competitiveness of the liquid chloroprene rubber and other liquid rubbers, and are beneficial to popularization and use.

In order to achieve the purpose, the invention is realized by the following technical scheme: a method for preparing liquid chloroprene rubber by step polymerization comprises the steps of heating chloroprene monomers dissolved in methylbenzene and a molecular weight regulator under the protection of nitrogen, adding an oil-soluble initiator to initiate reaction to obtain active species, taking the obtained active species as an initiator of secondary polymerization reaction, adding the initiator into a chloroprene monomer solution dissolved in methylbenzene and a molecular weight regulator reaction system, continuing the polymerization reaction, and adding a terminator to terminate the reaction after the reaction is finished, thus obtaining the liquid chloroprene rubber.

In the preparation system of the active species: 100 parts by weight of 2-chloro-1, 3-butadiene monomer is dissolved in 80 parts by weight of toluene, 20 to 80 parts by weight of molecular weight regulator is added, and 0.2 to 0.8 part by weight of initiator is added after dissolution for reaction.

In the system of the secondary polymerization reaction: dissolving 1000 parts by weight of chloroprene monomer in 800 parts by weight of toluene, adding 60-150 parts by weight of molecular weight regulator, adding 50 parts by weight of active species after dissolving, and adding 0.5-1 part by weight of terminator after reaction.

The molecular weight regulator is any one of diisopropyl disulfide orthoester, dodecyl mercaptan or thioglycolic acid; the oil-soluble initiator is cumene hydroperoxide, dibenzoyl peroxide or azobisisobutyronitrile; the terminator is any one of antioxidant TBC, antioxidant 264, antioxidant 1010 or antioxidant 168.

The method comprises the following specific steps:

(1) preparing reactive species: uniformly mixing chloroprene monomers and toluene in proportion, adding a molecular weight regulator into the mixed solution, fully stirring and dissolving, heating to 45-55 ℃ under the protection of nitrogen, adding an initiator, and reacting for 38-48h to obtain active species;

2) and preparing liquid chloroprene rubber: uniformly mixing chloroprene monomers and toluene, adding a molecular weight regulator, fully stirring and dissolving, heating to 45-55 ℃ under the protection of nitrogen, adding the prepared active species, reacting for 3-8 hours, adding a terminator into the system, and terminating the reaction;

3) and (3) product treatment: after the reaction is ended, concentrating under reduced pressure at room temperature, raising the temperature to 75 ℃ until no bubbles are generated, and distilling out toluene, a part of dimer and other compounds with smaller molecular weight; meanwhile, no methylbenzene is generated at the condenser, and the precipitated product is repeatedly washed by methanol or ethanol for 3-5 times to obtain the liquid chloroprene rubber.

Preferably: in the step (1), the reaction temperature is 55 ℃, and the reaction time is 48 hours; in the step (2), the reaction temperature is 55 ℃, and the reaction time is 8 h.

The liquid chloroprene rubber is prepared by adopting the method.

The mass of each raw material added in the experimental process is calculated based on the mass of the chloroprene monomer.

The liquid chloroprene rubber prepared by the invention has the advantages of short polymerization period, high monomer conversion rate in unit time, proper viscosity and good controllability.

The temperature at which the reaction is initiated cannot be too high because chloroprene has a relatively low boiling point and is technically limited, but the activation temperature of the conventional initiators is generally high regardless of whether they are azo-type or peroxy-type, so that solution polymerization is not easy to proceed in practice although chloroprene has relatively high reactivity.

The invention adopts a polymerization method for preparing liquid chloroprene rubber solution by step polymerization, and adds the polymerization product of the previous experiment into the next reaction system, so that the polymerization reaction is faster, and the polymerization period can be shortened to about 20 percent of the original period. The solution polymerization after the initiation of the polymerization system containing a large amount of active species is utilized, the reaction is easier to carry out, the efficiency is high, and the environmental protection performance of the product is good.

According to the invention, liquid chloroprene rubbers with different viscosities can be obtained by changing the amounts of the regulator and the initiator used in the reaction, and then a part of the liquid chloroprene rubbers can be used as active species to prepare final products with different viscosities.

After the prepared liquid chloroprene rubber is subjected to solution reaction for a certain time, active groups in the system are obviously increased, the reaction is accelerated, a great number of active species are contained after the reaction is finished, and a part of the liquid chloroprene rubber is taken out from the system and added into a monomer solution of the next polymerization reaction, so that the reaction speed can quickly reach an ideal speed, and the time and the energy consumption can be saved. The reaction method is similar to a seed polymerization method in emulsion polymerization, an initiator is hardly added in the subsequent reaction, and the obtained product after the reaction is finished has light color, small smell and good solvent reusability and meets the requirement of environmental protection.

The invention has the beneficial effects that: the invention applies the seed polymerization method to the solution polymerization process of the liquid chloroprene rubber, so that the preparation and production efficiency of the liquid chloroprene rubber is improved to a great extent, and the obtained product is more environment-friendly.

The preparation method of the liquid chloroprene rubber has the advantages of simple process operation, short polymerization period, high conversion rate and low production cost. The prepared liquid chloroprene rubber has light color and good environmental protection property, and is beneficial to industrial application.

Drawings

FIG. 1 shows the washing and purification of liquid neoprene, wherein: 1 is methanol washing liquid chloroprene rubber; 2, standing and precipitating liquid chloroprene rubber; 3 is viscous final product liquid chloroprene rubber.

Detailed Description

The present invention is further illustrated by the following specific examples, which are not intended to limit the scope of the invention.

Example 1: firstly, preparing reactive species: 100g of chloroprene monomer and 80g of toluene are uniformly mixed, 15g of diisopropyl disulfide orthoester is added, the mixture is fully stirred and dissolved, the temperature is raised to 55 ℃ under the protection of nitrogen, 3g of cumene hydroperoxide is added, the reaction is carried out for 48 hours, the toluene is removed, and the viscosity of the liquid chloroprene rubber is 6780.

Secondly, preparing liquid chloroprene rubber: mixing 1000g of chloroprene monomer and 800g of toluene uniformly, adding 150g of diisopropyl disulfide orthoester, fully stirring and dissolving, heating to 55 ℃ under the protection of nitrogen, adding 50g of prepared active species, reacting for 8 hours, adding 0.5g of TBC into the system, and stopping the reaction.

And (3) product treatment: the reaction solution was distilled under reduced pressure at room temperature using a reduced pressure rotary evaporator, and then the temperature was gradually increased to 75 ℃ until no more bubbles were generated and no toluene was generated at the condenser, as shown in fig. 1, and the precipitated product was repeatedly washed with methanol 3 to 5 times. As shown in fig. 1, 2, the liquid chloroprene rubber is left to stand and precipitate; as shown in 3 in figure 1, the liquid chloroprene rubber containing few volatile substances, being relatively environment-friendly, light in color and small in smell is prepared. The product viscosity was found to be 34600 and the yield of liquid neoprene was 70%, transparent, slightly yellowish, sticky with a faint odor.

Example 2: firstly, preparing reactive species: 100g of chloroprene monomer and 80g of toluene are uniformly mixed, 10g of dodecyl mercaptan is added, the mixture is fully stirred and dissolved, the temperature is raised to 55 ℃ under the protection of nitrogen, 3g of cumene hydroperoxide is added, the reaction is carried out for 48 hours, the toluene is removed, and the viscosity of the liquid chloroprene rubber is 5700.

Secondly, preparing liquid chloroprene rubber: mixing 1000g of chloroprene monomer and 800g of toluene uniformly, adding 100g of dodecyl mercaptan, fully stirring and dissolving, heating to 55 ℃ under the protection of nitrogen, adding 50g of prepared active species, reacting for 8 hours, adding 0.5g of TBC into the system, and stopping the reaction.

And (3) product treatment: and (3) distilling the reaction solution at room temperature under reduced pressure by using a reduced pressure rotary evaporator, gradually increasing the temperature to 75 ℃ until no bubbles are generated, simultaneously, no methylbenzene is generated at a condenser, and repeatedly washing the precipitated product for 3-5 times by using methanol. The product viscosity was found to be 32400, the yield of liquid neoprene was found to be 71%, it was transparent and slightly yellowish viscous, and the smell was weak.

Example 3: firstly, preparing reactive species: 100g of chloroprene monomer and 80g of toluene are uniformly mixed, 6g of thioglycolic acid is added, the mixture is fully stirred and dissolved, the temperature is raised to 55 ℃ under the protection of nitrogen, 3g of cumene hydroperoxide is added, the reaction is carried out for 48 hours, the toluene is removed, and the viscosity of the liquid chloroprene rubber is 7080.

Secondly, preparing liquid chloroprene rubber: mixing 1000g of chloroprene monomer and 800g of toluene uniformly, adding 60g of thioglycolic acid, fully stirring and dissolving, heating to 55 ℃ under the protection of nitrogen, adding 50g of prepared active species, reacting for 8 hours, adding 0.5g of TBC into the system, and stopping the reaction.

And (3) product treatment: and (3) distilling the reaction solution at room temperature under reduced pressure by using a reduced pressure rotary evaporator, gradually increasing the temperature to 75 ℃ until no bubbles are generated, simultaneously, no methylbenzene is generated at a condenser, and repeatedly washing the precipitated product for 3-5 times by using methanol. The product viscosity was found to be 47600 and the yield of liquid neoprene was 66% and was transparent, slightly yellowish, viscous and smelly.

Example 4: firstly, preparing reactive species: 100g of chloroprene monomer and 80g of toluene are uniformly mixed, 15g of diisopropyl disulfide orthoester is added, the mixture is fully stirred and dissolved, the temperature is raised to 55 ℃ under the protection of nitrogen, 4g of dibenzoyl peroxide is added, the reaction is carried out for 48 hours, the toluene is removed, and the viscosity of the liquid chloroprene rubber is measured to be 11780.

Secondly, preparing liquid chloroprene rubber: mixing 1000g of chloroprene monomer and 800g of toluene uniformly, adding 150g of diisopropyl disulfide orthoester, fully stirring and dissolving, heating to 55 ℃ under the protection of nitrogen, adding 50g of prepared active species, reacting for 8 hours, adding 0.5g of TBC into the system, and stopping the reaction.

And (3) product treatment: and (3) distilling the reaction solution at room temperature under reduced pressure by using a reduced pressure rotary evaporator, gradually increasing the temperature to 75 ℃ until no bubbles are generated, simultaneously, no methylbenzene is generated at a condenser, and repeatedly washing the precipitated product for 3-5 times by using methanol. The product viscosity was found to be 54600, the yield of liquid neoprene was 72%, it was transparent and slightly yellowish thick with a faint odor.

Example 5: firstly, preparing reactive species: 100g of chloroprene monomer and 80g of toluene are mixed uniformly, 10g of dodecyl mercaptan is added, the mixture is fully stirred and dissolved, the temperature is raised to 55 ℃ under the protection of nitrogen, 4g of dibenzoyl peroxide is added, the reaction is carried out for 48 hours, the toluene is removed, and the viscosity of the liquid chloroprene rubber is 9700.

Secondly, preparing liquid chloroprene rubber: mixing 1000g of chloroprene monomer and 800g of toluene uniformly, adding 100g of dodecyl mercaptan, fully stirring and dissolving, heating to 55 ℃ under the protection of nitrogen, adding 50g of prepared active species, reacting for 8 hours, adding 0.5g of TBC into the system, and stopping the reaction.

And (3) product treatment: and (3) distilling the reaction solution at room temperature under reduced pressure by using a reduced pressure rotary evaporator, gradually increasing the temperature to 75 ℃ until no bubbles are generated, simultaneously, no methylbenzene is generated at a condenser, and repeatedly washing the precipitated product for 3-5 times by using methanol. The product viscosity was 48400 and the yield of liquid neoprene was 67%, transparent, slightly yellowish, sticky, and weak in odor.

Example 6: firstly, preparing reactive species: 100g of chloroprene monomer and 80g of toluene are mixed uniformly, 6g of thioglycollic acid is added, the mixture is fully stirred and dissolved, the temperature is raised to 55 ℃ under the protection of nitrogen, 4g of dibenzoyl peroxide is added, the reaction is carried out for 48 hours, the toluene is removed, and the viscosity of the liquid chloroprene rubber is 12080.

Secondly, preparing liquid chloroprene rubber: mixing 1000g of chloroprene monomer and 800g of toluene uniformly, adding 60g of thioglycolic acid, fully stirring and dissolving, heating to 55 ℃ under the protection of nitrogen, adding 50g of prepared active species, reacting for 8 hours, adding 0.5g of TBC into the system, and stopping the reaction.

And (3) product treatment: and (3) distilling the reaction solution at room temperature under reduced pressure by using a reduced pressure rotary evaporator, gradually increasing the temperature to 75 ℃ until no bubbles are generated, simultaneously, no methylbenzene is generated at a condenser, and repeatedly washing the precipitated product for 3-5 times by using methanol. The product viscosity was found to be 57520, the yield of liquid neoprene was 68%, it was transparent and slightly yellowish in consistency, and the smell was slightly strong.

Experimental example: different regulators and initiators and the same regulators and initiators but different dosages are adopted to detect the properties of the prepared liquid chloroprene rubber such as quality, viscosity and the like. The choice of modifier and initiator is shown in table 1.

Table 1: data table of relationship between viscosity of liquid chloroprene rubber and dosage of regulator and initiator

The data in the above table show the relationship between viscosity and modifier and initiator, and it can be seen from experiments 1 to 9 that, in any molecular weight modifier, the product viscosity increases greatly when the amount is reduced, wherein the effect on viscosity when the amount of diisopropyl disulfide orthoester is changed is significantly greater than that of thioglycolic acid.

From experiments 10 to 18, it can be seen that, when the amount of the molecular weight regulator is constant, the viscosity of the product increases with the amount of the initiator, which is less than that of the regulator, and the increase decreases when the amount of the initiator reaches a certain level. It was found by experiment that the product obtained with thioglycolic acid as modifier smells slightly more strongly than diisopropyl disulfide orthoester and dodecyl mercaptan and the colour difference was not significant. The toluene content in the product after vacuum distillation and multiple washing purification is within 60 ppm.

The viscosity of the obtained liquid chloroprene rubber can be obviously changed by changing the dosage of the regulator, and the viscosity of the liquid chloroprene rubber can be influenced to a certain extent by changing the dosage of the initiator, but the overall change is not as much as the influence of the regulator.