JPS5811895B2 - Gomukariyuusokushinhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for promoting rubber vulcanization,
More specifically, (in the formula, R represents an alkyl group, X represents a linear or branched lower alkyl group or lower alkoxy group, and n represents an integer of 1 or 2.

This is a method for vulcanizing natural rubber and/or synthetic rubber, which is characterized in that one or more of the compounds represented by the following formulas are used as a vulcanization accelerator.

Conventionally, 2-mercaptobenzothiazole, dibenzothiazole disulfide, N-tert-butyl-2-benzothiazyl-sulfenamide, etc. have been used as muddying accelerators for rubber. The workability was not always satisfactory.

As a result of research into a method for accelerating vulcanization that does not have the above drawbacks, the present inventors found that the benzothiazole compound represented by the general formula (■) can be used as an accelerator to be added to a rubber mixture containing natural or synthetic rubber. The present invention was completed based on the discovery that the results were very good.

When the novel benzothiazole compound of the present invention is used, it is possible not only to significantly improve the aging and fatigue properties of vulcanized rubber, but also to achieve significantly higher strength than known benzothiazole vulcanization accelerators. , giving a highly elastic vulcanized rubber.

When using the novel benzothiazole compounds according to the process of the invention, also in the case of raw rubber mixtures with the addition of bioactive fillers, reinforcing fillers and also optionally anti-aging agents and anti-ozone protectants. Even in the case of mixtures containing 20% or more, these new benzothiazole compounds have an excellent effect on safely and reliably processing, making it possible to use high temperatures for mixing and injection. As a result, the mixing and processing times can therefore be significantly reduced.

It is also possible to easily process the raw rubber mixture and vulcanize it in a relatively narrow temperature range.

The vulcanization accelerator according to the present invention can be used for natural rubber, synthetic natural rubber, butadiene-styrene copolymer rubber, butadiene rubber, nitrile rubber, and the like.

In carrying out the method of the invention, the vulcanization accelerator of the invention is mixed with the rubber together with a vulcanizing agent, reinforcing carbon black or other filler, and then the rubber is vulcanized by conventional methods.

The blending ratio of these new accelerators is not particularly limited, but it is generally sufficient to add them in an amount of about 0.1 to 4% (by weight) based on the raw rubber content.

When producing vulcanized rubber using synthetic rubber, the range of 0.2 to 4% is usually good, with 0.6% being especially suitable.
~3%.

Moreover, these vulcanization accelerators may be used alone,
Further, two or more of the compounds represented by the general formula (■) may be used together, or they may be used in combination with a conventionally known vulcanization accelerator as appropriate.

The benzothiazole compound used in the method of the present invention is produced, for example, as follows.

Next, Table 1 shows 20 representative examples of compounds according to the present invention.

Next, examples of the method of the present invention will be shown.

Example 1 SBR-1712 (Japan Synthetic Rubber) 100 parts Highly aromatic oil 50 HAF (N-330) 75 u Each of the above formulations was mixed with about 50 parts according to a conventional method.
Roll knead at ℃ to make dough.

This kneaded dough was taken and left at room temperature for one day, and then re-kneaded with rolls under the same conditions as above to a thickness of 1.3 to 2.0 mm for the vulcanization test.
mm plate, and for Mooney viscosity test, thickness 9~
Divide into 10 mm plates.

(1) Vulcanization test: Cut the re-kneaded plate into an appropriate size and cut it into 20 x 20 cm.
Place it in a plate-shaped mold of size m and press under the following conditions.

Temperature: 140°C Pressure: 39 kg/crA Time: 10 minutes, 20 minutes, 40 minutes, 80 minutes The press sheet has a thickness of 1.3 to 1.6 mm. From now on 3
A strength test was conducted by punching out a No. 1 dumbbell test piece, and the hardness was measured by stacking several sheets.

All measurements were conducted in accordance with the method described in JIS K6301.

The results of the test are shown in Tables 2 and 3.

(2) Mooney viscosity test Circular test pieces with a diameter of 11/2'' (38.1 mm) were punched out from the re-kneaded plate and subjected to Mooney viscosity (100°C) and scorch tests at 125°C according to the method described in JIS K6300. .

The measurement results are shown in Table 4.

As is clear from Tables 2 and 3, compared to conventionally known benzothiazole-based vulcanization accelerators (control materials), the present invention provides the highest strength within 40 minutes of vulcanization when added to natural rubber and SBR. , breaking strength and elongation are both significantly increased, making it possible to produce excellent rubber with high strength and high elasticity.

Furthermore, as can be seen from Table 4, the accelerators of the present invention exhibit approximately the same scorch properties as the known vulcanization accelerators.

From the above, the compound of the present invention can be added in an amount of about 0.1 to 4%, preferably 0.6 to 3%, based on the raw rubber content, regardless of whether it is 5BR (styrene-butadiene rubber) or natural rubber. Compared to known intermittent vulcanization accelerators, the breaking strength shows an increase of about 10-30% at optimum vulcanization, and in particular reaches even 30% in SBR.

Also, the elongation increases by more than 40%.

In other words, when this vulcanization accelerator is used, the workability and hardness are
It is possible to produce excellent rubber with high strength and high elasticity without changing from conventional accelerators.

Claims (1)

[Scope of Claims] 1 General formula (wherein R is a lower alkyl group having 1 to 3 carbon atoms, X is a linear or branched lower alkyl group having 1 to 4 carbon atoms, n
represents an integer of 1 or 2. 1. A method for vulcanizing natural rubber and/or synthetic rubber, which comprises using one or more of the compounds represented by the following as a vulcanization accelerator.