JP7516960B2 - Chlorinated polymer and its manufacturing method - Google Patents

Description

The present invention relates to chlorinated polymers used in paints, coatings, etc., and to a method for producing the same.

Chlorinated polymers are polymers that are excellent in weather resistance, oil resistance, chemical resistance, heat resistance, and flame retardancy, and are widely used in paints, coatings, adhesives, and other applications (see, for example, Non-Patent Document 1). In many cases, they are used in these applications as solutions dissolved in solvents such as toluene, xylene, and chloroform (see, for example, Patent Document 1). In this case, there are concerns that the presence or absence or amount of insoluble components may affect processability, workability, or quality variation. On the other hand, chlorinated polymers can be produced in solution using the solvent method or in water using the aqueous suspension method, and the solution method is superior in terms of chlorination uniformity, physical properties, and quality. However, insoluble components have been an issue in producing solutions of chlorinated polymers produced by the solution method.

JP 2001-354912 A

NACET-6A Technical Committee Report on Chlorinated Rubber Coatings Application Techniques, Physical Properties, and Chemical Resistance

The present invention was made in consideration of the above problems, and its purpose is to provide a chlorinated polymer that has excellent solubility and can be used to make paints, coatings, adhesives, etc. that have excellent workability and quality stability.

The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, the present invention relates to the following items [1] to [4].
[1] A chlorinated polymer having a chlorine content of 60.0 to 75.0% by weight and containing 0.01 to 1.0% by weight of 1,1,2-trichloroethane.
[2] The chlorinated polymer according to [1], wherein the raw polymer is at least one selected from the group consisting of natural rubber, polyisoprene and chloroprene rubber.
[3] The chlorinated polymer according to [1] or [2], characterized in that a precipitate obtained by high-speed centrifugation of a chloroform solution in which the chlorinated polymer is dissolved at a concentration of 5% by weight at 10,000 rpm for 10 minutes accounts for 5.0% by weight or less of the dissolved chlorinated polymer.
[4] The method for producing a chlorinated polymer according to any one of [1] to [3], characterized in that the polymer is dissolved in a solvent and reacted with a chlorinating agent.

The chlorinated polymer of the present invention has a low content of insoluble components when dissolved, making it possible to manufacture paints, coatings, and adhesives that have excellent processability and workability.

The present invention is described in detail below.

The chlorinated polymer of the present invention is a polymer obtained by chlorinating various raw polymers. Examples of raw polymers include natural rubber, polyisoprene, polybutadiene, polychloroprene, polyethylene, polypropylene, EPDM, SBR, NBR, etc., and these can be used alone or in combination. Considering performance, processability, and productivity for paint or coating applications, natural rubber, polyisoprene, polybutadiene, polychloroprene, and polyethylene are preferred.

There are two methods for chlorinating raw polymers: the aqueous suspension method and the solution method. The solution method is preferred in terms of the uniformity of chlorine addition, solubility characteristics, amount of insoluble components, and quality stability of the resulting chlorinated polymer.

The solution method involves dissolving the raw polymer in a solvent and adding a chlorinating agent under appropriate temperature and pressure conditions to chlorinate the polymer.

The solvent used for chlorination in the solution method is not particularly limited, but from the standpoint of solubility and reactivity, examples include carbon tetrachloride, 1,1,1-trichloroethane, 1,1,2-trichloroethane, chloroform, chlorobenzene, 1,1,2-trichloroethylene, etc., but 1,1,2-trichloroethane is preferred to reduce insoluble components.

The raw polymer solution concentration when chlorinating using the solution method is not particularly limited, but taking into consideration productivity and preventing a decrease in workability due to high viscosity, a concentration of 3.5 wt% to 7.0 wt% is preferable.

The chlorine content of the chlorinated polymer of the present invention is preferably 60.0 to 75.0 wt% in order to provide good oil resistance, chemical resistance, flame retardancy and processability. More preferably, it is 64.0 wt% or more and 70.0 wt% or less.

For good solubility properties, it is desirable to contain 1,1,2-trichloroethane at 0.01 wt% or more and 1.0 wt% or less, more preferably 0.05 wt% or more and 0.5 wt% or less.

The chlorinating agent used for chlorinating the chlorinated polymer of the present invention is not particularly specified, and chlorinating agents such as chlorine gas, thionyl chloride, and sulfuryl chloride can be used. These may be used alone or in combination. In addition, a catalyst that promotes the chlorination reaction may be used as necessary. Examples of the catalyst include azo compounds and organic peroxides. Examples of azo compounds include α,α'-azobisisobutyronitrile, azobiscyclohexanecarbonitrile, and 2,2'-azobis(2,4-dimethylvaleronitrile), and examples of organic peroxides include benzoyl peroxide, acetyl peroxide, t-butyl peroxide, and t-butyl perbenzoate. Among these, azo compounds are preferred because they are highly stable in handling, and α,α'-azobisisobutyronitrile is even more preferred because they allow moderate chlorination and chlorosulfonation reactions to proceed.

The reaction temperature is not particularly limited as long as the chlorination reaction proceeds. For example, 15 to 110°C is preferable, and 30 to 80°C is preferable to achieve both a moderate chlorination reaction rate and reaction stability.

The reaction pressure is not particularly limited as long as the chlorination reaction proceeds. For example, 0 to 1.0 megapascals is preferred, and 0.1 to 0.5 megapascals is even more preferred in order to ensure that the chlorination proceeds appropriately.

When an acidic gas is used as the chlorinating agent, the acidic gas remaining in the reaction solution after the chlorination reaction is completed is removed by introducing an inert gas such as nitrogen. There are no particular limitations on the temperature conditions during removal, but a temperature of 50 to 100°C is preferred for stable and efficient acid removal.

After removing the remaining acid gases, the resulting solution can be used as is or after replacing it with a solvent such as toluene or xylene, but it is also possible to separate the solvent and chlorinated polymer using equipment such as steam distillation, a drum dryer, a vented extruder, or a spray dryer, and obtain only the product chlorinated polymer.

The resulting chlorinated polymer solution or the product chlorinated polymer can be used to make paints, coatings, adhesives, etc.

The present invention will be specifically described with reference to the following examples. However, the present invention is not limited to these examples.

<Insoluble component measurement method>
0.5 g of the chlorinated polymer obtained in the present invention was dissolved in 9.5 g of chloroform to prepare a 5 wt % chloroform solution. The solution was centrifuged at 10,000 rpm for 10 minutes to separate insoluble components. The insoluble components were dried at 120° C. for 2.0 hours, and then the weight was measured to calculate the proportion of the insoluble components.
<Measurement of 1,1,2-trichloroethane amount>
The chlorinated polymer was dissolved in chloroform to prepare a solution having a concentration of 2.0% by weight, and monochlorobenzene was added as an internal standard substance to calculate the content by the internal standard method using gas chromatography.

Example 1
720 g of 1,1,2-trichloroethane and 36 g of natural rubber RSS#3 were charged into a 1.0 liter glass autoclave. The internal temperature was raised to 70° C., and chlorine gas was continuously introduced into the reactor at a flow rate of 200 ml/min for 8 hours while maintaining the internal pressure at 0.1 MPa.

After the chlorination reaction was completed, the pressure was returned to normal pressure, the internal temperature was raised to 90°C, and nitrogen gas was then introduced to remove any acidic gas remaining in the reaction liquid over a period of 1.5 hours.

The resulting chlorinated rubber solution was extruded in a vented extruder at 160°C to separate the chlorinated polymer from the solvent.

Analysis revealed that the chlorine content of the chlorinated polymer was 64.6% by weight, and it contained 0.1% by weight of 1,1,2-trichloroethane. The insoluble components were 4.5% by weight.

Example 2
The raw material natural rubber was changed to SMR-10, and chlorination was carried out in the same manner as in Example 1. The chlorine content of the obtained chlorinated polymer was 65.5% by weight, and it contained 0.23% by weight of 1,1,2-trichloroethane. The insoluble component was 3.4% by weight.

Example 3
The raw material was changed to polyisoprene, and chlorination was carried out in the same manner as in Example 1.

The chlorine content of the resulting chlorinated polymer was 66.2% by weight, and it contained 0.35% by weight of 1,1,2-trichloroethane. The insoluble components were 2.6% by weight.

Comparative Example 1
Chlorination was carried out in the same manner as in Example 1, except that the solvent was changed from 1,1,2-trichloroethane to carbon tetrachloride.

The chlorine content of the resulting chlorinated polymer was 66.8% by weight and contained no 1,1,2-trichloroethane. The insoluble components were 10.6% by weight.

Comparative Example 2
Chlorination was carried out in the same manner as in Example 1, except that the solvent was changed to chloroform.

The chlorine content of the resulting chlorinated polymer was 64.8% by weight and contained no 1,1,2-trichloroethane. The insoluble components were 8.3% by weight.

The chlorinated polymer of the present invention has a low content of insoluble components when dissolved in chloroform, making it easy to process and work with, and enabling the manufacture of paints, coatings, adhesives, etc.

Claims (2)

A chlorinated polymer obtained by chlorinating at least one raw material polymer selected from the group consisting of natural rubber, polyisoprene and chloroprene rubber, the chlorine content being 60.0 to 75.0% by weight, containing 0.01 to 1.0% by weight of 1,1,2-trichloroethane , and the precipitate obtained by centrifuging a chloroform solution in which the chlorinated polymer is dissolved at a concentration of 5% by weight at 10,000 rpm for 10 minutes is 5.0% by weight or less of the dissolved chlorinated polymer . The method for producing a chlorinated polymer according to claim 1, characterized in that at least one raw material polymer selected from the group consisting of natural rubber, polyisoprene and chloroprene rubber is reacted with a chlorinating agent in a state where the raw material polymer is dissolved in 1,1,2-trichloroethane.