JPH0119415B2 - - Google Patents

Description

[Detailed description of the invention]

This invention is based on chloroprene rubber (hereinafter referred to as "CR")
This invention relates to a chloroprene rubber vulcanization composition obtained by using a pyridazine derivative as a vulcanization accelerator. In general, compared to other diene rubbers, CR has
It is widely agreed that it has excellent ozone resistance, heat resistance, weather resistance, and oil resistance, and for this reason, it is used in large quantities as a so-called durable rubber for industrial parts. However, various additives play a large role in maximizing the characteristics of CR, and in particular, the method of using the vulcanization accelerator plays a large role. This effect is partly due to the fact that CR has fewer types of vulcanization accelerators than other diene rubbers. For example, in diene rubber, the vulcanization accelerators are thiazole compounds (2-mercaptobenzothiazole, dibenzothiazolyl disulfide, etc.), sulfenamide compounds (N-
cyclohexyl-2-benzothiazolyl sulfenamide, N-oxydiethylene-2-benzothiazolyl sulfenamide, etc.), guanidine compounds (1,3-diphenylguanidine, 1,3
-di-o-tolylguanidine, etc.), thiuram compounds (tetramethylthiuram disulfide, tetramethylthiuram monosulfide, etc.), dithioate salt compounds (zinc dimethyldithiocarbamate, sodium diethyldithiocarbamate, etc.) While it is spread across various systems,
To date, the most effective vulcanization accelerators in CR are thiourea compounds (ethylenethiourea, tetramethylthiourea, etc.).
It can be said to be a system of In particular, among these thiourea compounds, ethylene thiourea (hereinafter abbreviated as "ETU") is the most widely used. Compared to other thiourea compounds, this ETU is preferred because of (1) good heat resistance of the vulcanizate, (2) good normal physical properties of the vulcanizate, and (3) additives. This is based on the small amount (0.5 to 1.0 phr). However, with the recent development of the automobile industry, and from the standpoint of resource conservation, rubber parts with even greater durability are becoming necessary. In particular, there is a need for CR vulcanized compositions to have heat resistance several steps higher than that of the current vulcanized compositions using ETU as a vulcanization accelerator. In order to meet this demand, research has been actively conducted to improve heat resistance by relying on anti-aging agents. but,
Since such countermeasures using anti-aging agents alone are insufficient, there is a strong demand for fundamentally increasing the heat resistance of vulcanized compositions essentially using vulcanization accelerators. An object of the present invention is to develop and provide a vulcanization accelerator for CR that should meet such demands. As a result of intensive research to achieve the above object, the inventors found that pyridazine derivatives are almost equivalent to ETU in terms of vulcanization rate and normal physical properties of vulcanized compositions, but the heat resistance of vulcanized compositions is In
It was discovered that the effect was superior to that of ETU, and based on this knowledge, the present invention was completed. The gist of this invention is a chloroprene rubber vulcanization composition comprising one or more pyridazine derivatives represented by the following general formula, or, or, as a vulcanization accelerator. general formula [However, R ¹ represents hydrogen or a methyl group, R ² represents hydrogen, or R ¹ −R ² represents −CH=CH−CH=CH−, and when R ³ is hydrogen, R ⁴ represents hydrogen or

[Formula], R ³ is

[Formula] When R ⁴ is

Represents [formula]. ] General formula [However, R ¹ represents hydrogen or a methyl group, R ² represents hydrogen, or R ¹ -R ² represents -CH=CH-CH=CH-. ] General formula [However, R ¹ represents hydrogen or a methyl group, R ² represents hydrogen, or R ¹ -R ² represents -CH=CH-CH=CH-. ] A detailed and specific explanation of the constituent elements of this invention will be described below. The pyridazine derivative used as the vulcanization accelerator for CR according to the present invention can be produced by a known synthesis method described below. The following are representative examples. That is, pyridazine-
3,6-dithiol, 4-methylpyridazine-
3,6-dithiol, phthalazine-1,4-dithiol, pyridazine-3,6-bistiuronium dichloride, bis(6-mercapto-3-pyridazinyl) disulfide, 1-methyl-3-methylthiopyridazine-6-thione , 1,2-dimethylpyridazine-3,6-dithione, etc., but are not limited to these compounds. Also,
Preferably, those having a small molecular weight are economical since they require a small amount to be added. Among those compounds, pyridazine-3,6-
Dithiol, 4-methylpyridazine-3,6-dithiol, phthalazine-1,4-dithiol, pyridazine-3,6-bistiuronium dichloride, etc. correspond to the above general formula, and they are published by Manpei Shitani: Nihon Kagaku. It can be easily produced according to the following reaction formula in accordance with the method published in Magazine Vol. 81, No. 10, p. 1604 (1960). That is, when 3,6-dichloropyridazines are heated with thiourea in the presence of a suitable solvent, pyridazine-3,6-bistiuronium dichloride is obtained. This bistiuronium salt is heated and hydrolyzed in an aqueous sodium hydroxide solution and then neutralized with hydrochloric acid to obtain the desired product, pyridazine-3,6-dithiol. Also, in the compound of the general formula, R ³ is hydrogen and R ⁴
but

Bis(6-mercapto-3-pyridazinyl) disulfide of [formula] can be easily prepared according to the following reaction formula based on the method of Manpei Motoya: Nippon Kagaku Zasshi Vol. 81, No. 10, p. 1604 (1960). can be manufactured to That is, pyridazine dithiols are oxidized with iodine in the presence of a basic solvent such as pyridine, the solvent is distilled off, and then dissolved in an aqueous sodium hydroxide solution, filtered, and neutralized with hydrochloric acid to obtain the desired product. It will be done. In addition, 1-methyl-3-methylthiopyridazine-6-thione, etc. correspond to the general formula, and Gordon Bieberlin: The Journal
of the chemical society, parkin
1199 pages (1974) [Gordon B, Barlin:
The Journal of the Chemical Society,
Perkin, p. 1199 (1974)], it can be easily produced according to the following reaction formula. That is, bismethylthiopyridazine is obtained by methylating pyridazine dithiols with methyl iodide in the presence of a suitable solvent and alkali, distilling off the solvent, and removing the insoluble portion in an aqueous sodium hydroxide solution. This bismethylthiopyridazine is reacted at room temperature in the presence of a suitable solvent and methyl iodide, the solvent and excess methyl iodide are distilled off, and the residue is recrystallized from tert-butyl alcohol to form bismethylpyridazine methiodide. is obtained, which is thermally decomposed in a suitable solvent, the solvent is distilled off, and then recrystallized from ligroin to obtain the desired product. In addition, on the other hand, 1,2-dimethylpyridazine-3,
6-dithion, etc. correspond to the general formula described above, and are described in Gordon B. Berlin: The Journal of the Chemical Society,
Parkin 1199 pages (1974) [Gordon B,
Barlin: The Journal of the Chemical
Society, Perkin, p. 1199 (1974)] according to the following reaction formula. That is, 1,2-dimethylpyridazine-3,
6-diones are heated with phosphorus pentasulfide in the presence of an appropriate solvent, then after the solvent is distilled off, water is added to decompose excess phosphorus pentasulfide, extracted using an appropriate solvent, and then extracted using a column. The desired product can be obtained by separating it. Table 1 shows the characteristic values of the pyridazine derivative according to the present invention.

[Table] Next, embodiments of the present invention will be described. The chloroprene rubber vulcanized composition of this invention is manufactured according to conventional rubber processing methods. and,
When the pyridazine derivative according to this invention is added to CR as a vulcanization accelerator, the amount added is CR100.
The amount is 0.1 to 5 parts by weight, preferably 0.3 to 1.5 parts by weight. In this case, if it is less than 0.1 part by weight, the vulcanization rate will drop significantly and it is not practical. On the other hand, adding 5 parts by weight or more does not inhibit the vulcanized composition, but no particular effect is observed and it is uneconomical. In addition, the chloroprene rubber vulcanization composition of the present invention contains metal oxides such as zinc oxide, magnesium oxide, and lead oxide, as well as commonly used vulcanization accelerators for diene rubber, anti-aging agents, and fillers. , pigments, plasticizers, and other compounding agents, and sulfur can also be used. Furthermore, the method of using the pyridazine derivative according to the present invention as a vulcanization accelerator is no different from that of conventional vulcanization accelerators for CR. Therefore, conventionally
Vulcanization can be carried out using a method commonly used in the CR vulcanization process, such as press vulcanization or in-die extension vulcanization, or using a vulcanization machine. Next, the effects of this invention will be described. The pyridazine derivative according to the present invention is a common thiourea compound vulcanization accelerator, especially ETU, in terms of vulcanization temperature and in combination with other vulcanization accelerators.
Or, since it is completely equivalent to tetramethylthiourea (MTU), the normal physical properties of the resulting CR vulcanized composition are almost equivalent to ETU, which is currently most widely used. However, the heat resistance in the heat aging test was 10% higher than that of the ETU vulcanizate.
A remarkable feature is recognized when the effect shows an improvement of ~30%. Hereinafter, the effects of the present invention will be explained in more detail with reference to Examples, but the invention is not limited thereto. Example 1 Measurement of vulcanization time of unvulcanized composition Based on the formulation shown in Table 2 below, a predetermined amount of the compound according to the present invention or a comparative compound as a test vulcanization accelerator was added according to a conventional rubber processing method. Knead using a kneading roll machine and meet the Japan Rubber Association standards.
In accordance with SRIS3102-1977 (vulcanization test method using a vulcanization tester), rheometer vulcanization test (Toyo Seishinki, die diameter 30 mm, amplitude ±3°, frequency
6cpm, test temperature 170°C). The results are shown in Table-3. Table-2 Chloroprene rubber W 100 parts by weight Zinc oxide 5 Magnesium oxide 4 Carbon black SRF 30 Sample flow accelerator 1/200 mol

[Table] Example 2 Measurement of normal state physical properties of vulcanized compositions Unvulcanized compositions containing each of the test vulcanization accelerators prepared in Example 1 were press-cured at 150°C for 40 minutes. Regarding vulcanized compositions, JIS
Normal state physical property values were measured in accordance with K6301-1975 (vulcanized rubber physical test method). The results are shown in Table 4.

【table】

[Table] Example 3 Heat aging test of vulcanized compositions JIS
In accordance with the test method of K6301-1975 (vulcanized rubber physical test method) 6.6 (test tube heat aging test), 120℃
A heat aging test was conducted, and the rate of change or change in physical property values after 96 hours of the test period was measured. The results are shown in Table-5.

[Table] As can be seen from the above examples, the vulcanization composition obtained by using the pyridazine derivative according to the present invention as a vulcanization accelerator for chloroprene rubber can be obtained by using a conventionally known and commonly used vulcanization accelerator. It is clear that among the various physical properties of the vulcanized composition obtained using this method, heat resistance is particularly effective.

Claims (1)

[Scope of Claims] 1. A chloroprene rubber vulcanization composition comprising one or more pyridazine derivatives represented by the following general formula, or, or, as a vulcanization accelerator. general formula [However, R ¹ represents hydrogen or a methyl group, R ² represents hydrogen, or R ¹ -R ² represents -CH=CH-CH=CH-, and when R ³ is hydrogen, R ⁴ is hydrogen or [Formula ], and when R ³ is [formula], R ⁴ represents [formula]. ] General formula [However, R ¹ represents hydrogen or a methyl group, R ² represents hydrogen, or R ¹ -R ² represents -CH=CH-CH=CH-. ] General formula [However, R ¹ represents hydrogen or a methyl group, R ² represents hydrogen, or R ¹ -R ² represents -CH=CH-CH=CH-. ]