JPS6358696B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rubber surface treatment method. More specifically, the present invention relates to a rubber surface treatment method that provides a molded rubber material with excellent friction and wear characteristics. Conventionally, various methods have been proposed for improving the surface friction and wear characteristics of molded rubber materials, and they can be broadly classified into the following three types. (1) Chemical treatment: Modify the surface of molded rubber materials by reacting chemicals with rubber, such as sulfuric acid treatment and halogen treatment. This processing method has problems unique to wet processing, such as safety and hygiene and pollution, since it handles hazardous materials, and also has the disadvantage of easily deteriorating the rubber. (2) Physical treatment: Cover-coat the surface of the molded rubber material with another material by means such as coating, dipping, or painting. This treatment method has the problem of adhesion to rubber, making it difficult to apply to products with complex shapes and structures, and has the drawback of increasing equipment costs and increasing costs. (3) Energy irradiation treatment: When molded rubber materials are irradiated with appropriate energy such as ultraviolet rays or corona discharge, the deterioration of the rubber tends to be accelerated compared to normal conditions, for example, 100%
When the stretched state is observed with a scanning electron microscope, numerous cracks are observed, making it difficult to apply it to improving the friction and wear characteristics of rubber. The present inventor has conducted various studies on rubber surface treatment methods that do not cause these problems or drawbacks found in conventional techniques aimed at improving the surface friction and abrasion characteristics of molded rubber materials, and has developed a new technology called high-frequency plasma. By applying the method of high frequency sputter etching, which is a field, to molded rubber materials,
It has been found that the above problems can be effectively solved. Therefore, the present invention relates to a rubber surface treatment method, and this rubber surface treatment is performed by treating the surface of a molded rubber material attached to one of a pair of electrodes to a temperature of 10 ^-2 to 10 -2 .
10 ^-1 Torr (approximately 1~10Pa) pressure condition and 100W
This is done by high frequency sputter etching under the following output conditions. Conventionally, the surface of polymer materials such as polyethylene and polytetrafluoroethylene has been treated with oxygen plasma or non-oxidizing plasma, especially rare gas such as helium or argon, or hydrogen gas plasma to improve surface adhesion. However, the causes of this effect include the formation of a cross-linked film with a large molecular weight on the material surface and the weak sputtering of contaminants and low-molecular compounds attached to the material surface due to plasma gas. Removal based on effectiveness is mentioned (Chemistry Area Special Issue No. 111, "Low Temperature Plasma Chemistry", pp. 50-51). However, with these resinous polymeric materials, although their surface adhesion may be a problem, it is not the case with rubber materials that their tackiness or increased coefficient of friction is a problem. It can be said that it is unlikely. Therefore, although sputter etching has long been known to improve the surface adhesion of resinous polymeric materials, it has not been shown that sputter etching can improve the surface friction and wear characteristics of rubbery polymeric materials. It can be said that there is nothing out there that can predict what can be achieved. In high frequency sputter etching, approximately 10 ^-2 ~
High frequency discharge (frequency 13.56MHz) is performed under low pressure conditions of 10 ^-1 Torr (approximately 1 to 10Pa). High-frequency discharge is generally performed using an inert gas such as argon, neon, or krypton, but in consideration of ionization rate, cost, etc., it is desirable to use argon. In addition, helium and air can also be used, and it has been confirmed that they provide almost the same treatment effect as when using argon. The molded rubber material to be surface-treated is attached to one electrode of a pair of electrodes having a constant distance therebetween by suitable means. The distance between the electrodes is set in relation to the size of the electrodes, but if the distance is longer than a certain value, the sputter etching effect will be uneven due to misalignment of the molded rubber material at the installed position. become invisible. In this regard, in order to further reduce the unevenness of the sputter etching effect due to the shape of the molded rubber material, it is possible to minimize the effect by rotating the molded rubber material during processing. Further, when the output (incident wave - reflected wave) is 100 W or less, if the value of the number of watts x the discharge time is constant, the amount of spatter etching will be approximately the same. Specifically, the surface treatment of the molded rubber material is performed, for example, according to the illustrated flow sheet. That is, a molded rubber material 4 is attached to one electrode 3 side of a pair of electrodes 2 and 3 with a distance of 30 mm between the electrodes installed in a bell gear type chamber 1 by an appropriate means. The pressure inside the chamber is reduced to the order of 10 ^-7 Torr (approximately 10 ^-5 Pa) by an exhaust line 5 connected to an oil rotary pump and an oil diffusion pump (both not shown). Argon gas is introduced through the gas introduction line 6 to reduce the pressure inside the chamber to 10 ^-4 Torr (approx.
10 ^-2 Pa). Then adjust the main valve to increase the pressure to 10 ^-2
~10 ^-1 Torr (approximately 1 to 10 Pa). A high frequency wave oscillated by a high frequency oscillator 7 is adjusted by a matching device 8 so that the difference between the incident wave and the reflected wave is maximized. Note that the output is variable. The discharge is performed by argon, and positive ions of argon attack the electrode on the rubber material side, causing spatter etching at this time. After discharging for a certain period of time and stopping the discharge, a leak is caused and the surface-treated molded rubber material is taken out. The most important feature of the rubber surface treatment method according to the present invention is that such a treatment method can be applied even when there is no unsaturated bond in the main chain of the rubber molecules constituting the molding material. The object of the present invention is to greatly improve the surface friction and wear characteristics of molded rubber materials. In conventional surface treatment methods, especially chemical surface treatment methods, it is difficult to apply such treatment methods unless unsaturated bonds are present in the main chain of the rubber molecule, and therefore the scope of application is limited. There was a limit. However, in the present invention, not only is there no limit to the scope of application, but the improvement in surface friction and wear properties is not sacrificed in exchange for deterioration of other rubber properties. The effectiveness is very satisfactory. Therefore, the rubber surface treatment method of the present invention can be effectively applied to natural rubber and various synthetic rubber molding materials. Examples of synthetic rubber include styrene butadiene rubber, acrylonitrile butadiene rubber, acrylic rubber, chloroprene rubber,
It can be applied to a wide range of materials including hydrin rubber, ethylene propylene rubber, and fluorine rubber. Next, the present invention will be explained with reference to examples. Example 1 The following rubber vulcanized compound was kneaded on a roll,
Press vulcanization was performed at 180°C for 4 minutes to create a sample rubber sheet with a thickness of 2 mm. Nitrile rubber (Nippon Zeon product DN-302)
100 parts by weight FEF carbon black 60 Zinc white 5 parts by weight Stearic acid 1 Tetramethylthiuram disulfide 2.5 Sulfur 0.8 N-cyclohexyl-2-benzothiazylsulfinamide 2.0 This sample rubber sheet was subjected to the above-mentioned sputter etching device. 1 high frequency discharge with an output of 90W
The kinetic friction coefficient was measured for 2 minutes, 2 minutes or 3 minutes. The coefficient of dynamic friction (μ) is
Measurements were made using a Suzuki friction and wear tester under the following conditions. Rotation speed: 150 rpm (0.179 m/sec) constant Load: 1 to 3 Kg (0.5 to 1.5 Kg/ ^cm2 ) variable Contact area: 2 ^cm 2Mating material: S45C Measurement time: variable from 1 to 30 minutes The results obtained are , as shown in Tables 1 and 2 below. For comparison, data obtained for an untreated sample rubber sheet and a sample rubber sheet treated with sulfuric acid are also shown. The sulfuric acid treatment was performed by immersing the sample in 1st class reagent concentrated sulfuric acid (95%) at 20°C for 4 seconds.
It was immediately washed with plenty of water and dried.
The sample rubber sheet treated with sulfuric acid had numerous cracks even when it was slightly bent.

【table】

[Table] Example 2 The following rubber vulcanized compound was kneaded on a roll,
Press vulcanization was carried out at 190°C for 10 minutes, followed by secondary vulcanization at 200°C for 30 hours to prepare a sample rubber sheet with a thickness of 2 mm. Fluorine rubber (DuPont product Viton E)
60C) 100 parts by weight MT carbon black 20 Magnesium oxide 3 Calcium hydroxide 6 This sample rubber sheet was subjected to high-frequency discharge at an output of 80W for 1 time using the sputter etching device described above.
The kinetic friction coefficient was measured for 2 minutes, 2 minutes or 3 minutes. The results obtained are shown in Table 3 below. In addition,
For comparison, data obtained for an untreated sample rubber sheet and a halogen-treated sample rubber sheet are also shown. Halogen treatment is
Immerse for 5 minutes at 20°C in a solution prepared by adding 1 part of glacial acetic acid to 100 parts of a 1% aqueous solution of grade 1 sodium hypochlorite (available chlorine 0.05%), then immediately wash with water and dry. It was done. Most of the sample rubber sheets treated in this manner remained untreated, indicating that halogen treatment is not effective on rubbers other than those having unsaturated bonds in the main chain.

[Table] Example 3 The following rubber vulcanized compound was kneaded on a roll,
Press vulcanization was performed at 190°C for 8 minutes to create a sample rubber sheet with a thickness of 2 mm. Acrylic rubber (Japan Oil Seal Industrial Products A-
1095) 100 parts by weight HF carbon black 40 Stearic acid 1 Dibasic lead phosphite 5 Hexamethylene diamine carbamate 1.1 This sample rubber sheet was subjected to high frequency discharge at an output of 50 W using the sputter etching device described above for 50 minutes.
The kinetic friction coefficient was measured for 1 minute. The results obtained are shown in Table 4 below. For comparison, data obtained for an untreated sample rubber sheet is also shown.

【table】 [Brief explanation of the drawing]

The drawing is a flow sheet for carrying out one embodiment of the method of the present invention. In this drawing, reference numeral 1
2 and 3 are electrodes, 4 is a molded rubber material, 7 is a high frequency oscillator, and 8 is a matching device, respectively.

Claims (1)

[Claims] 1. The surface of a molded rubber material made of a rubber selected from natural rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, hydrin rubber, ethylene-propylene rubber, and fluorine rubber attached to one of a pair of electrodes. , 10 ^-2 to 10 ^-1 Torr (approximately 1 to
A rubber surface treatment method characterized by performing high-frequency sputter etching under a pressure condition of 10 Pa) and a power output of 100 W or less.