JPH0222338A - Molded product of rubber excellent in ozone resistance - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a rubber molded product, particularly a rubber molded product with improved ozone resistance.

[Prior Art 1] Various rubber materials are used for molded products depending on their use and required characteristics, but cracks occur on the surface for various reasons. Examples of cracks include non-directional network cracks (crazing) caused by sunlight, cracks caused by dynamic repeated deformation, and cracks caused by ozone.

By the way, it is said that the air contains at most 1 to 5 ppbm of ozone. It is known that ozone present in such a small amount has a large influence on the deterioration of vulcanized rubber and the generation of cracks, and that cracks occur when rubber molded products are subjected to slight distortion. Most of the rubber molded products in practical use are modified to some degree.

Therefore, it is necessary to improve the feed itself to prevent cracks caused by ozone.

It is well known that various rubber materials, especially those having double bonds in their main chains, have poor ozone resistance. However, there are cases in which it is necessary to use this type of material in relation to other properties. For example, styrene for tires.
A rubber material based on butadiene rubber (SBR) is used.

Conventionally, in order to improve the ozone resistance of rubber materials that have double bonds in their main chains, various anti-ozone deterioration inhibitors have been added to the rubber materials, and paraffin wax has been added to the rubber materials in slightly larger amounts. A method has been adopted in which the material is added to cause blooming on the surface of the material, creating a protective film on the surface.

[Problems to be Solved by the Invention] However, the method of incorporating an anti-ozone deterioration agent in order to impart ozone resistance to a rubber material can extend the crack generation time to some extent, but is not a perfect method; If used in a way that causes significant distortion, DI'
It has the disadvantage of generating cracks in the l. In addition, many of these ozone deterioration inhibitors contain amine compounds, and when they come into contact with other products, they may stain (discolor) the products, which is a problem.

On the other hand, the method of adding a slightly larger amount of paraffin wax, etc. has the disadvantage that ozone resistance will drop significantly and cracks will occur if the paraffin wax film that protects the surface is lost due to rubbing etc. There was a problem with sexuality.

An object of the present invention is to provide a rubber molded product that can eliminate the drawbacks of the prior art described above and can significantly improve ozone resistance.

[Means and effects for solving the problems] The gist of the present invention is that the surface of a rubber base material is fluorinated by plasma treatment, and the ozone resistance is greatly improved by erosion.

Here, rubber materials with double bonds in the main chain include natural rubber, isoprene rubber, butadiene rubber, styrene rubber,
Examples include butadiene rubber, chloroprene rubber, nitrile rubber, and polynorbonene rubber.

In addition, these can be used individually or in mixture of 2 or more types.

In addition, examples of fluorine compounds include CF, CF31'', CF
, octafluorocyclobutane, and the like.

[Example] A rubber material with the standard composition shown in Table 1 was heated at 60°C.
After kneading with an inch roll, the mixture was press-vulcanized at 150° C. for 30 minutes to obtain a sheet with a thickness of 2 m. From now on 15X1
A 40s test piece was prepared.

This sample was placed in a suspended cryogenic plasma generator with an external electrode, and the pressure was adjusted to Q, 5 Torr while evacuating the plasma chamber and flowing a fluorine compound gas at a rate of 20IIIl/sin. It was adjusted to Thereafter, plasma was generated using a high frequency wave with a frequency of 13.56 MHz and an output of 50 W, and the sample was subjected to plasma treatment for 10 to 30 minutes.

Example 1 was a case in which detrafluoromethane was used as the fluorine-based compound, and Example 2 was a case in which octafluorocyclobutane was used.

Comparative Example 1 is a sample with the standard composition without plasma treatment, Comparative Example 2 is a sample with the standard composition and 2P of paraffin wax.
The sample to which hr was added, Comparative Example 3, was N.

N'-dibutyl-p-phinyl diamine (DPPD>
This is a sample to which 2Phr was added.

The ozone resistance test was conducted using a low-temperature ozone weather meter using a dynamic ozone test at an ozone concentration of 50±5 ppba.
+, test piece vulcanization conditions 150℃ x 30 minutes, dynamic compatibility O ~ 1
The test was carried out under conditions of 0% (5A centrifugal system) and a test temperature of 40°C.

Table Ozone crack evaluation criteria were determined according to Table 2 based on JIS K630175 (vulcanized rubber physical test method).

A small number of visible cracks occurred. Further, Comparative Example 3 in which the ozone deterioration inhibitor DPPD was added was more effective than Comparative Example 2, but cracks that were visible to the naked eye occurred after 14 hours.

Table 3 As shown in Table 3, in Example 1.2 in which plasma fluorinated surface treatment was performed, no cracking was observed after 240 hours, whereas in Example 1.2, which was subjected to plasma fluorination surface treatment, no cracking was observed after 240 hours. In Comparative Example 1, in which paraffin wax was not added, many cracks smaller than 1s1 occurred after 5 hours, and in Comparative Example 2, in which paraffin wax was added, it was slightly better than in the case without paraffin wax, but it was confirmed with the naked eye after 7 hours (Note). 18 For example, 5 in 5 (B-3) indicates crack initiation time (hr), and 8-3 in parentheses indicates no cracking according to JIS K 6301-7.5.

[Effects of the Invention] As explained above, according to the present invention, it is possible to provide a rubber molded product in which the ozone resistance of a rubber material having a double bond in its main chain is significantly improved.

Claims (1)

[Claims] 1. A rubber molded product characterized in that the surface of a rubber material having a double bond in its main chain is subjected to plasma fluorination treatment.