JPS5891737A - Vulcanizing composition for chloroprene rubber - Google Patents

Abstract

PURPOSE:To provide the titled composition especially excellent in scorch resistance during processing, prepared by compounding a thioamide compound as a vulcanization promotor. CONSTITUTION:The titled composition has a thioamide compound shown by formula (wherein R<1> and R<2> are each 1-4C alkyl or cyclohexyl, or R<1> and R<2> are combined together to form -(CH2)n-or-CH2CH2OCH2CH2-; m is 0-16; and n is 4 or 5) (e.g., N, N-dimethylacetamide, N-pentamethylenepropionthioamide) as a vulcanization promotor compounded therein. The thioamide compound is nearly equal to ethyleneurea which is used most widely in the vulcanization speed, the ordinary physical values of a vulcanizing composition and heat resistance but extremely excellent in scorch resistance during processing. Therefore, it is unnecessary to use a scorch retarder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tetrachloroprene rubber vulcanization composition obtained by using a thioamide compound as a vulcanization accelerator for chloroprene rubber (hereinafter abbreviated as "OR").

In general, OR has superior ozone resistance, heat resistance, weather resistance, and oil resistance compared to other diene rubbers, and for this reason, it is widely known that it is used in large quantities in industrial parts as a so-called durable rubber. This is where they match.

However, in order to maximize the performance of such OR characteristics, various additives have a large effect, and in particular, the method of using the vulcanization accelerator has a large effect. One reason for this effect is that OR has fewer types of vulcanization accelerators than other diene rubbers. For example, vulcanization accelerators for diene rubbers include thiazole compounds (2-mercaptobenzothiazole, dibenzothiazyl disulfide, etc.), sulfenamide compounds (N-cyclohexyl-2-benzothiazolylsulfenamide, N-oxydiethylene-2-benzothiazolylsulfenamide, etc.), guanidine compounds (l,3-diphenylguanidine, l,3-di0-)zylguanidine).

Thiuram compounds (tetramethylthiuram disulfide, tetramethylthiuram disulfide, etc.), dithioate compounds (dimethyldithiocarbamine vertebral surface r″, sodium dithyl dithiocarbamate, etc.) and multi-M”&v
On the other hand, the most effective vulcanization accelerators for CR in the current issue are thiourea compounds (ethylenethiourea, tetramethylthiourea, etc.).

In particular, the most widely used thiourea compound is ethylene thiourea (hereinafter referred to as "ETU").
It is abbreviated as. ).

The reason why this 17'T 1 piece is preferred and praised is that, compared to other thiourea compounds, 1) the heat resistance of the vulcanizate is good, 2) the normal physical properties of the vulcanizate are good, and 3) ) The reason for this is that the amount added is small (0, s~/, Ophr). However, with the recent development of the automobile industry, there has been a demand for higher durability of rubber parts from the viewpoint of resource saving measures. For this reason, more advanced processing is required for rubber parts, and as the processing process inevitably becomes more contact-separated, the scorch stability during processing of OR (C) used as an accelerator for unvulcanized rubber. There is a need to slow down the speed by several steps.

In order to meet this demand, we have developed the conventional JP-A Shoj,! ! ' −
/ 3 j-/ + Although scorch inhibitors have been proposed in Publication No. 7, none of them are satisfactory.

Daikaisha Co., Ltd. Published October 20, 1939 (P., 2 & ~ 2). Furthermore, the use of such scorch inhibitors is uneconomical. For this reason, there is a strong demand for a vulcanization accelerator that can essentially stabilize scorch during processing and provide a vulcanizate with good normal physical properties.

An object of the present invention is to develop and provide a vulcanization accelerator for OR that should meet such demands.

In order to achieve the above object, the inventors conducted extensive research and found that the present invention exhibits excellent effects, and based on this knowledge, they completed the present invention.

The gist of this invention is a chloroprene rubber vulcanization composition containing one or more thioamide compounds represented by the following general formula as a vulcanization accelerator.

A detailed and specific explanation of the constituent elements of this invention will be given below.

The thioamide compound used as the vulcanization accelerator for OR according to the present invention can be produced by the synthesis method described below. The following are representative examples. That is, N.

N-dimethylacetothioamide, N,N-dimethylpropionthioamide, N-methyl-Nn-butylpropionthioamide, N,N-dicyclohexylpropionthioamide, N-pentamethylenepropionthioamide,
N-oxydiethylenepropionthioamide, N,N-
Examples include dicyclohexylstearoylthioamide, but are not limited to these compounds. Moreover, it is preferable that the molecular weight is small, since the addition amount can be small, which is economical.

These compounds can be easily produced according to the reaction formula below.

Amide compound Genjun L! J (target)
That is, the desired product can be obtained by heating the amide compound with niline pentasulfide in the presence of a suitable solvent, cooling, and then distilling off the solvent.

The characteristic values of typical thioamide compounds according to the present invention are shown in Table 1.

Next, embodiments of the present invention will be described.

The chloroprene vulcanized compositions of this invention are manufactured according to conventional rubber processing methods. When compounding CRK with the thioamide compound according to the present invention as a vulcanization accelerator,
The amount added is 0.7- to 1 part by weight of 0R10.
is in parts by weight, preferably O65~/j parts by weight. In this case, if it is less than 0.7 parts 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.

The chloroprene rubber vulcanization composition of the present invention also contains metal oxides such as zinc oxide, magnesium oxide, and lead oxide, as well as commonly used vulcanization accelerators and anti-aging agents for diene rubber.

Fillers, reinforcing agents, pigments, plasticizers, and other compounding agents can be added, and sulfur can also be used.

Therefore, vulcanization can be carried out using methods commonly used in conventional OR vulcanization processes, such as press vulcanization, injection vulcanization, and vulcanization machines.

Next, the effects of this invention will be described.

7- The thioamide compound according to the present invention has a high vulcanization humidity and other vulcanization accelerators for OR, and is completely compatible with conventional thiourea compound vulcanization accelerators, especially ETU or tetramethylthiourea (TIATU). Therefore, the normal physical properties of the resulting OR vulcanized composition are almost the same as those of ETU, which is currently most widely used. However, Mooney's hooch time (t, t) takes 10 to 13 minutes longer than when using ]'eTU;
and the lowest Mooney value (V
A remarkable feature that clearly indicates the effect that m) is lower than ETU by io~/j% is observed (Table 3).

Hereinafter, the effects of the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Production example /, Production of N,N-dimethylacetothioamide N,N-dimethylacetamide, 2/, Ig and xylene 2j Oml! The mixture was placed in a fourth r 00 ml flask, and 2.2 g of niline trisulfide was added thereto, followed by stirring for g hours under reflux. Then, after cooling,
When the solvent of the filtered p-liquid was distilled off, 20% of the black solid matter was removed.
．． I got it. The sublimation purified product of this substance has a melting point of 73.0.
~74I! , 0°C white crystals. Sulfur analysis confirmed that it was N,N-dimethylacetothioamide.

Sulfur analysis 3 /,! ; 7% (theoretical value 3/, 0
7%) Other compounds according to this invention were produced in the same manner, and each was identified from the sulfur analysis value (Table-)
).

Example 1. Measurement of scourge time and vulcanization rate of unvulcanized compositions Compounds according to the present invention or comparative compounds according to the present invention were used as test vulcanization accelerators according to the conventional rubber processing method based on the formulation shown in Table 2 below. A predetermined amount of the above is kneaded using a kneading roll machine to make an unvulcanized composition, and these are subjected to Mooney scorch according to JK SK Otsu 300-/R 7II (Unvulcanized Rubber Physical Testing Method) K. Tests were conducted and the Japan Rubber Association Standards SR Engineering S 310.2-/977 (
Rheometer vulcanization test (Testing machine manufactured by Toyo Seiki: die diameter 30 mm).

Amplitude: ±3°, Frequency: 1 cpm, Temperature: 730°C
) was used to measure the vulcanization rate. The results are shown in Table 3.
Shown below.

Table -2゜Chloroprene rubber-w 1ooH part oxidation Zinc S Magnesium oxide Carbon black SRF JQ #Example 2.
Example 1: Measurement of normal state physical properties of vulcanized composition. Regarding the vulcanized compositions prepared by press-curing the unvulcanized compositions containing the respective test vulcanization accelerators at iso°C for 0 minutes, J.
Normal state physical property values were measured in accordance with '0■ Sulfur rubber physical test method).

The results are shown in Table μ.

Example 3. Heat Aging Test for Vulcanized Compositions Regarding the vulcanized compositions containing each of the test vulcanization accelerators prepared in Example-1, J Kogyo SKA30/-/
97! (Vulcanized Rubber Physical Test Methods) A heat aging test was conducted at 20″O in accordance with the test method of 4B (Test Tube Heat Aging Test), and the test period was 4/!r~9 hours later. The rate of change or change in physical property values was measured.The results are shown in Table 5.
, as shown in .

As can be seen from the above examples, the vulcanization composition obtained by using the thioamide compound prepared according to the present invention as a vulcanization accelerator for KuriT] Brene rubber can be obtained by using a known vulcanization accelerator that has been conventionally used. It is clear that the scorch stability among the properties of the vulcanized composition is particularly excellent compared to the vulcanized composition obtained using the above-mentioned method.

patent applicant 17- Japanese Patent Application Publication No. 58-91737 (7)

Claims (1)

[Scope of Claims] A chloroprene rubber vulcanization composition comprising /IMi or two or more of the thioamide compounds represented by the following general formula as a vulcanization accelerator. general formula