JP2817982B2 - Rubber belt - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a chloroprene rubber belt having high hardness and modulus, excellent physical properties in normal conditions, and excellent heat resistance.

[Conventional technology]

Conventionally, natural rubber, styrene-butadiene rubber, and chloroprene rubber have been used for power transmission belts. In particular, chloroprene rubber (hereinafter often abbreviated as “CR”) is particularly superior to natural rubber and styrene-butadiene rubber. Because of its excellent heat resistance, it is widely used in various belts for automobiles.

In addition, as a rubber material for the belt, the hardness of the belt,
High modulus and normal physical properties (tensile strength, elongation)
Since it is desirable that CR is excellent, a sulfur-modified CR is generally used among CRs.

However, in the automobile industry, the temperature of the engine room of the automobile is higher than before due to the demand for energy saving, high performance, and compactness. Along with this, the demand for rubber belts having better heat resistance has been increasing year by year. From such a background, various studies have been made on improving the heat resistance of CR, but it cannot be said that it is still sufficient.

As a method for improving the heat resistance of the CR vulcanizate, for example, it is known to use a non-sulfur-modified CR as a base polymer. is there.

On the other hand, as a method for increasing the hardness or modulus of the vulcanized product, a method of increasing the amount of carbon black or silica as a reinforcing filler is generally known. Because the Mooney viscosity increases,
Not only does workability during processing deteriorate, but also the elongation and durability (fatigue properties, etc.) of the vulcanizate decrease.

[Problems to be solved by the invention]

The present invention has been made in view of the above points, and an object of the present invention is to provide a chloroprene-based rubber belt having high hardness and modulus, and excellent in normal physical properties and heat resistance.

[Means for solving the problem]

Means for Solving the ProblemsThe present inventors have conducted intensive studies in order to achieve the above object, utilizing the properties of 2,3-dichlorobutadiene-1,3 as a polymer structural unit as a rubber material for a belt. As a result, by mixing a polymer consisting of an extremely high proportion of 2,3-dichlorobutadiene-1,3 with a chloroprene-based polymer, high hardness and modulus can be obtained without impairing elongation, workability, and other physical properties. The present inventors have found that a chloroprene-based rubber composition having the same can be obtained, and this finding has led to the completion of the present invention.

That is, the present invention provides a chloroprene-based polymer containing at least 80% by weight of chloroprene units and a 2,3-dichlorobutadiene-1,3-based polymer containing at least 70% by weight of 2,3-dichlorobutadiene-1,3 units ( However, the rubber belt is formed by molding and vulcanizing a rubber composition containing no sulfur as a copolymer component).

The chloroprene-based polymer that can be used in the present invention can be produced by radical polymerization generally used for polymerization of chloroprene. In this case, the chloroprene-based polymer may be a homopolymer of chloroprene or chloroprene and a monomer copolymerizable therewith.
It is possible to use a copolymer which has been subjected to a copolymerization reaction so as not to exceed the weight%. There is no particular limitation on the monomer copolymerizable with chloroprene, and for example, 2,3-dichlorobutadiene-1,3, styrene, acrylonitrile, sulfur, or the like can be used, or two or more of these may be used. .

As the emulsifier, chain transfer agent, polymerization initiator and polymerization terminator used in the polymerization reaction, any of those commonly used in emulsion polymerization of chloroprene can be suitably used.

The polymerization conditions are not particularly limited, but the polymerization temperature is 10 ° C.
To 50 ° C. and the monomer conversion in the range of 50% to 90% are preferably used.

After the polymerization is completed, unreacted monomers are removed by a known method to obtain a chloroprene-based polymer latex.

The 2,3-dichlorobutadiene-1,3-based polymer as the other component of the present invention is produced by a general radical emulsion polymerization method, similarly to the chloroprene-based polymer. The 2,3-dichlorobutadiene-1,3 polymer is a homopolymer of 2,3-dichlorobutadiene-1,3 or other copolymers which can be copolymerized with 2,3-dichlorobutadiene-1,3. Monomer to monomer total amount 3
A copolymer copolymerized within a range not exceeding 0% by weight can be used. Monomers copolymerizable with 2,3-dichlorobutadiene-1,3 include, for example, chloroprene, acrylonitrile and the like, and one or more of them may be used. Among them, chloroprene is preferred.

The same emulsifier, chain transfer agent, polymerization initiator, and polymerization terminator as those used for the chloroprene polymer may be used for the emulsified weight.

The polymerization conditions are not particularly limited. In general, the polymerization may be performed at a polymerization temperature of 10 ° C. to 70 ° C. and a monomer conversion of 50% or more.

After completion of the polymerization, unreacted monomers were removed in the same manner as in the chloroprene-based polymer, and
A polymer latex is obtained.

The rubber composition for a rubber belt according to the present invention is obtained by mixing the above two polymers. In mixing, there are a method of mixing and drying after mixing both in the state of a polymer latex, and a method of mixing after isolating and drying each alone, but a method of mixing in a state of latex from the viewpoint of mixing properties and the like. Is preferred.

Chloroprene-based polymer and 2,3-dichlorobutadiene
The mixing ratio of the 1,3 polymers is 50 to 99 parts by weight of the chloroprene polymer, and 1 to 50 parts by weight of the 2,3-dichlorobutadiene-1,3 polymer when the sum of the two is 100 parts by weight. Is preferred,
Furthermore, 70 to 97 parts by weight of a chloroprene polymer and 3 to 30 parts by weight of a 2,3-dichlorobutadiene-1,3 polymer are particularly preferable.

The rubber belt of the present invention comprises a chloroprene polymer and 2,3
A mixture with a dichlorobutadiene-1,3-based polymer is kneaded together with a rubber compounding agent by a conventional method, and the kneaded material is vulcanized. In this kneading, it is preferable to use a rubber composition obtained by previously mixing a chloroprene-based polymer and a 2,3-dichlorobutadiene-1,3-based polymer as described above. Chloroprene polymer and 2,3-dichlorobutadiene
A method in which two kinds of rubbers are mixed by adding each of them for the first time in a place where a 1,3-based polymer is mixed with a rubber compounding agent may be used.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples. In the examples, parts are by weight unless otherwise specified.

Chloroprene polymer and 2,3-dichlorobutadiene-1,3 polymer were produced by the following method.

Emulsion polymerization of the chloroprene polymer was carried out in a nitrogen atmosphere using a 5 l four-neck flask as a reactor in a nitrogen atmosphere at a polymerization temperature of 40 ° C. while continuously dropping potassium persulfate. As soon as the conversion of the monomer reached 70%, 100 ppm of diethylhydrosylamine as a polymerization inhibitor was added to all the charged monomers to terminate the polymerization reaction. Unreacted monomers were removed using a steam stripping method.

2,3-dichlorobutadiene-1,3 polymer latex,
The chloroprene polymer latex was prepared in the same manner as in the chloroprene polymer latex except that 2,3-dichlorobutadiene-1,3 was used instead of chloroprene in Table 1.

Table 1 Chloroprene 100 parts Potassium rosinate 3.5 parts β-naphthalenesulfonic acid folimarin condensed part Nalorium salt 0.6 part Sodium hydroxide 0.3 part n-dodecyl mercaptan 0.2 part Water 150 parts Examples 1, 2 and Comparative Example 1 After mixing 2,3-dichlorobutadiene-1,3 polymer latex with the prepared chloroprene polymer latex, it was isolated and dried by a freeze-coagulation method, and the weight of Examples 1 and 2 and Comparative Example 1 shown in Table 2 was measured. A united composition (the mixing ratio is indicated by the polymer solid content) was obtained.

The obtained composition was blended with each of the chemicals according to the formulation shown in Table 2 and then press-vulcanized at 160 ° C. for 25 minutes to produce a vulcanized product. Table 2 shows the results of measurement of the physical properties and heat resistance in accordance with JISK-6301.

By comparing Examples 1 and 2 with Comparative Example 1, Example 1
It can be seen that the hardness and the modulus of each of Nos. 2 and 3 are improved.

[Effect of the Invention] From the above, the 2,3-dichlorobutadiene of the present invention-
It can be seen that the rubber belt using the 1,3-based polymer and the chloroprene-based polymer has a significantly improved hardness and modulus without impairing the properties of the chloroprene rubber.

In addition, since this rubber composition has an excellent balance of physical properties, it is expected to be used for industrial products other than belts.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C08L 7/00-21/02

Claims (1)

(57) [Claims] 1. A chloroprene polymer containing at least 80% by weight of a chloroprene unit and a 2,3-dichlorobutadiene-1,3 polymer containing at least 70% by weight of 1,3-dichlorobutadiene-1,3 units. A rubber belt obtained by molding and vulcanizing a rubber composition containing no sulfur as a copolymer component).