JPH06107716A - Production of chloroprene-based polymer - Google Patents

Abstract

PURPOSE:To produce a chloroprene-based polymer having high rigidity represented by tensile stress. CONSTITUTION:Chloroprene monomer is polymerized as a main monomer in the presence of a polythiol compound to produce a chloroprene-based polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a chloroprene polymer characterized by carrying out polymerization in the presence of a polythiol compound. The polymer exhibits high rigidity and is suitable for applications such as automobile boots, hoses and belts.

[0002]

2. Description of the Related Art Chloroprene polymers are used for various purposes because they have a good balance of physical properties such as general rubber physical properties, heat resistance, cold resistance and chemical resistance. However, in recent years, in applications such as boots and belts for automobiles, the stress received by the rubber material has become larger, and the deformation of the rubber material under the high stress accompanying it has become a problem. Therefore, these rubber materials are required to have so-called high rigidity, which is less deformable even under high stress.

Generally, as a method of increasing the rigidity of a rubber material, a method of adding a reinforcing agent such as carbon black is known. However, in this method, the excessive addition of the reinforcing agent causes a decrease in fatigue resistance, cold resistance, etc.,
The amount added is naturally limited, and therefore improvement of the chloroprene polymer itself is desired.

In producing the chloroprene polymer,
Usually, a chain transfer agent such as alkyl mercaptan or dialkylxanthogen disulfide is added to control the molecular weight. However, the chloroprene polymer obtained by this method is not at a satisfactory level in terms of rigidity.

[0005]

An object of the present invention is to obtain a chloroprene polymer having high rigidity represented by tensile stress.

[0006]

[Means for Solving the Problems] As a result of various studies to achieve this object, the inventors have found that a chloroprene polymer polymerized by using a specific chain transfer agent exhibits high rigidity. The present invention has been reached.

That is, the present invention is a method for producing a chloroprene-based polymer, which comprises polymerizing a chloroprene monomer as a main monomer in the presence of a polythiol compound.

The chloroprene polymer in the present invention means a homopolymer of 2-chloro-1,3-butadiene or 2
-Refers to a copolymer of chloro-1,3-butadiene and another monomer.

Here, the other monomer is 2-chloro-
There is no particular limitation as long as it can be copolymerized with 1,3-butadiene, for example, styrene, acrylonitrile, 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, acrylic acid, acrylic acid. Examples thereof include esters, methacrylic acid, methacrylic acid esters, isoprene, and 1,3-butadiene.

Further, the polythiol compound referred to in the present invention may be a compound having two or more thiol groups in the molecule, for example, an alkylenedithiol having 2 or more carbon atoms, di (2-mercaptoethyl) ether, p -Xylylenedithiol and the like.

The method for polymerizing the chloroprene polymer of the present invention is not particularly limited, and either emulsion polymerization or solution polymerization can be used, but emulsion polymerization is generally used.

[0012]

The present invention will be described in detail below with reference to examples.

Example 1 A 5-necked 4-necked flask was used as a reactor, 1,6-hexanedithiol was used as a polythiol compound in the polymerization formulation shown in Table 1, and potassium persulfate was added at a polymerization temperature of 40 ° C. under a nitrogen atmosphere. Was continuously added dropwise to carry out emulsion polymerization. When the monomer conversion rate reached 65%, 100 ppm of diethylhydroxylamine was added to all charged monomers to terminate the polymerization reaction, and unreacted monomers were removed by steam stripping method. did. Then, the obtained polymer was blended according to the formulation shown in Table 3 and kneaded with an open roll kneader, followed by press vulcanization at 141 ° C. for 25 minutes to obtain a vulcanized product according to JIS K-6301. Then, the physical properties were tested. The test results are shown in Table 1.

Example 2 Polymerization and tests were conducted in the same manner as in Example 1 except that 0.14 parts by weight of 1,10-decanedithiol was used instead of 1,6-hexanedithiol. The test results are shown in Table 1.

Comparative Example 1 Polymerization and tests were carried out in the same manner as in Example 1 except that 0.17 parts by weight of n-dodecyl mercaptan was used instead of the polythiol compound. The test results are shown in Table 1.

Example 3 In the polymerization formulation shown in Table 2, di (2
Polymerization and testing were carried out in the same manner as in Example 1 using -mercaptoethyl) ether. The test results are shown in Table 2.

Comparative Example 2 Polymerization and testing were carried out in the same manner as in Example 3 except that 0.22 parts by weight of n-dodecyl mercaptan was used instead of di (2-mercaptoethyl) ether. The test results are shown in Table 2.

[0018]

From the above results, it can be seen that the vulcanized product of the chloroprene polymer of the present invention exhibits a large tensile stress and a high rigidity.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

Claims (1)

[Claims] 1. A method for producing a chloroprene polymer, which comprises polymerizing a chloroprene monomer as a main monomer in the presence of a polythiol compound.