JPH0222339A - Rubber molded product with excellent ozone resistance - Google Patents

Abstract

PURPOSE:To obtain a molded rubber product improved in ozone resistance by subjecting the surface of a rubber material having double bonds in the backbone chain to plasma hydrogenation treatment. CONSTITUTION:A molded rubber product obtained by subjecting the surface of a rubber material having double bonds in the backbone chain to plasma hydrogenation treatment and saturating the double bonds in the backbone chain.

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] Various rubber materials are used for rubber molded products depending on their uses and required characteristics, but cracks occur on their surfaces for various reasons. The main types of cracks are 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 ppbs of ozone. It is known that ozone, which exists in small amounts, has a great effect on the deterioration and cracking of vulcanized rubber, and cracks and cracks occur even when rubber molded products are subjected to slight distortion. There is. Most of the rubber molded products in practical use undergo some deformation before use.

Therefore, in order to prevent the occurrence of cracks due to ozone, it is necessary to improve the monthly interest rate itself.

It is well known that among various rubber materials, those having a double bond in the main chain have poor ozone resistance. However, there are cases where this type of material must be used due to its other properties. For example, rubber materials based on styrene-butadiene rubber (SBR) are used for tires.

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, or paraffin wax filters have been used in a slightly larger amount. 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.

[Problem to be Solved by the Invention 1] However, the method of adding an anti-ozone deterioration agent to impart ozone resistance to a rubber material does not allow the cracks to spread to a certain degree. Although it is possible, it is not a perfect method, and it has the disadvantage that cracks can easily occur if it is used in a manner that is subjected to large amounts of strain.Additionally, many of these anti-ozone deterioration inhibitors contain amine compounds. This was a problem because some of the products could contaminate (change color) when they came into contact with Haku products.

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 that protects the surface is not properly maintained due to rubbing etc. There was a problem with durability.

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 problem] The gist of the present invention is that the surface of the rubber material is subjected to plasma hydrogenation treatment to saturate the double bonds in the main chain of the rubber, thereby significantly improving ozone resistance. This has been improved.

Here, examples of the rubber material having a double bond in the main chain include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, polypropylene rubber, 21-lyl rubber, polynorbornene, and the like.

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

[Example] A rubber material with the standard composition shown in Table 1 was heated at 60°C.
After kneading with an inch roll, press vulcanization was performed at 150°C for 30 minutes to form a 2# thick sheet. 15X from now on
A test piece of 14011+#+ was prepared.

This sample was placed in a capacitively coupled low-temperature plasma generator with an external electrode, and the inside of the plasma vessel was evacuated to generate olefin monomer gas of 20I11! /sin flow and the pressure was adjusted to 0.5 Torrk:. 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 hydrogenation treatment for 10 to 30 minutes.

Example 1 is a sample subjected to plasma hydrogenation treatment for 10 minutes.
1! Example 2 is trial r1 which was subjected to plasma hydrogenation treatment for 30 minutes.

Comparative example 1 is 4! ! Samples were subjected to plasma hydrogenation treatment with the same composition as they were; Comparative Example 2 was a sample with 2 Phr of paraffin wax added to the standard composition; Comparative Example 3 was N, N'-
Dibutyl-p-phenylenediamine (DPPD) 2Ph
This is a sample with r added.

The ozone resistance test uses a dynamic ozone test to determine the amount of low-temperature ozone sea urchin! - Using a meter, ozone 0 degrees 50 ± 59 pbl
, test piece vulcanization conditions: 150°C x 30 minutes, dynamic temperature: 0 to 10
% (eccentric cam type) and the test temperature was 40°C.

Table Ozone crack evaluation criteria were determined according to Table 2 based on JIS K6301-75 (vulcanized rubber physical theory method).

Comparative Example 2 in which surface fin wax was added was slightly better than the case in which no fin wax was added, but a small number of cracks that were visible to the naked eye occurred after 7 hours. In addition, Comparative Example 3 in which 0PPD@added ozone deterioration inhibitor was more effective than Comparative Example 2, but 14
Time I! Cracks that were visible to the naked eye appeared after the test.

Table 3 As shown in Table 3, in Example 1 in which the plasma hydrogenation surface treatment was performed for 10 minutes and 30 minutes, respectively, a small number of visible cracks occurred after 240 hours had passed.

In Example 2, cracks occurred after 240 hours! It was in good condition. On the other hand, in Comparative Example 1, which was not subjected to plasma treatment and did not contain anti-A-sin deterioration inhibitor, 1 #1 after 5 hours had passed.
A large number of cracks with a diameter of less than 10 (for example 5 (
B-3) 5 is crack initiation time (hr), B-3 in parentheses
indicates no tearing according to JIS K6301-75.

[Effects of the invention 1

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 has been subjected to plasma hydrogenation treatment.