JPS59218830A - Surface treatment process of rubber product - Google Patents

Abstract

PURPOSE:To produce at low cost a surface treated rubber product having anti adhesive and smooth slidable surface and further untifouling effect without the reducing of rubber property by exposing the rubber product to fluorine gas diluted to a specified concentration with inactive gas. CONSTITUTION:A rubber product is exposed to 0.1-20vol% fluorine gas diluted with inactive gas preferably for 1sec-5min under the condition of room temperature and atmosperic pressure. Fluorine of 0.002 or more atom is combined with carbon of 1 atom on the surface of said rubber product. Thus obtained rubber product may be used for the industrial products such as a packing and a bearing or for the medical products such as the pipe joint in a liquid transferring pipe circuit without cleaning by solution in that condition.

Description

[Detailed description of the invention] The invention relates to a surface treatment method for Meisen rubber products.

More specifically, the present invention relates to a method of fluorinating the surface of a rubber product by exposing the rubber product to a fluorine gas atmosphere for a short period of time.

Conventionally, rubber products have been used in large quantities in industrial products such as gaskets and bearings, and in medical products such as pipe joints in infusion circuits. However, rubber products are sticky,
In addition, due to the large coefficient of friction, when packaging rubber products or incorporating rubber products into other parts, the rubber products may stick together and become integrated, or the packaging bag number ζ 14 may become inconvenient, resulting in poor handling. In order to reduce the stickiness and M coefficient of the rubber products mentioned above and improve their handling properties, it has been widely practiced to chlorinate the surface of the rubber products by immersing them in a 111J solution of NaGe0 and ■Ce. . Although this method has the effect of lowering the coefficient of friction, it has poor workability because it uses a liquid, and water marks may remain on the surface of the rubber product due to poor drying conditions after cleaning. Furthermore, there has been a problem that the above-mentioned method causes excessive chlorination, which causes the surface of the treated rubber product to harden and cause micro-cracks.

Recently, in addition to the above treatment methods, the surface of rubber products has a low coefficient of friction.
A method of forming a fluororesin layer having excellent properties such as non-adhesion was proposed in Japanese Patent Publication No. 56650/1983.

This method involves melting a mixed gas of an inert gas and antimony pentafluoride gas to fluorinate the surface of the rubber product, and then converting the antimony compound remaining on the surface of the rubber product to an alkali metal. In this method, rubber products are removed with a carbon salt solution, and then the rubber product is washed with water and dried. Since the above method uses gaseous antimony pentafluoride, it is possible to form a uniform fluorinated layer on the entire surface regardless of the shape of the rubber product, and the fluorinated layer does not impair the properties of the rubber product. Although this method has excellent effects, cleaning and drying of the liquid used to remove the antimony compound remaining on the surface of the rubber product is required, and the problem of leaving water channels on the surface of the rubber product still remains. It remained as it was.

Such water channels on the surface must be avoided in medical products or non-registered products (ζ) as they reduce the commercial value.

The inventors of the present invention have made intensive studies to solve the problems of conventional surface treatment methods for comb products, and as a result have reached the invention number ζ. That is, the present invention uses 0 diluted with an inert gas.
, by exposing the rubber product to 1 to 208 M% fluorine gas, at least 0.002 or more fluorine atoms are bonded to one carbon atom on the surface of the rubber product. This is a method for surface treatment of products.

The novel idea of the present invention is to contact the rubber product with fluorine gas diluted with an inert gas.

Based on this idea, it is possible to uniformly fluorinate part or all of the surface of a rubber product without impairing the properties of the product, and the surface-treated rubber product can be used as is without cleaning with a solution. can.

The rubber products of the present invention include, for example, hydrocarbons, halogenated hydrocarbons (natural rubber, butadiene rubber, isoprene rubber, butadiene-styrene rubber, chloroprene rubber, ethylene-propylene rubber, copolymers of fluorine-containing monomers,
and similar products), which are molded from a vulcanizate using butadiene-nitrile rubber as a substrate.

The mixed gas to be brought into contact with the rubber product does not contain oxygen and has a concentration of 0.1
% to 20% (by volume) of fluorine gas and 99.1 to 80% (by volume) of a suitable inert gas such as nitrogen, argon, helium and their analogues. If oxygen coexists in the mixed gas, the oxygen may bond to the gumshi Q product, which is undesirable.The concentration of fluorine gas in the mixed gas may be reduced to zero
．． If it is less than 1%, it will take a long time to fluorinate the surface of the rubber product, which poses a practical problem. When fluorine is at this concentration, it reacts violently and is difficult to control.Furthermore, fluorine gas has a fluorine content, and once used, it is difficult to recover one fluorine gas, so it is economical to keep the fluorine gas concentration below 20%. It is true.

It is usually appropriate to use a fluorine gas concentration or a mixed gas with a concentration of 1% to 10%.

When treating rubber products according to the present invention, the treatment temperature and the pressure after diluting the fluorine gas can be arbitrarily selected within a wide range. The surface treatment is carried out at a general temperature of 0° C. to 100° C., preferably room temperature, and a pressure of 0.5 atm to 5 atm, preferably atmospheric pressure. Above condition #'i! The surface of the rubber product can be fluorinated in a relatively short time of about 1 second to 5 minutes.

The amount of fluorine required to reduce the tackiness and surface ordering coefficient of the rubber product may be within a small range.

The degree of fluorination on the surface of rubber products varies depending on the exposure time to fluorine gas and the concentration of fluorine gas, but the degree of fluorination on the surface of rubber products is usually determined using X-ray electron spectroscopy (BSOA).
) at least 0.0 per carbon atom as measured by
If 02 or more fluorine atoms are bonded, the stickiness and friction coefficient of the rubber product will be about 1/2 to 1 that of untreated rubber products.
It can be reduced to /6. Number of carbon atoms: 1 (i+M
If j is less than 0.00243, the object of the present invention will not be achieved. Further, even if zero or one or more fluorine atoms are bonded, no effect is required. Usually, 0.04 to 0.06 pieces of fluorine particles are suitable.

Rubber'9 product, in which 0.0024iIj of fluorine is bonded to one urea atom, shows no visible fluorine in the infrared absorption spectrum, but X-ray electron spectroscopy (Esch
), a fluorine peak is observed (7), while an untreated rubber product (ζ) shows no fluorine peak at all.

The fluorination equipment used in the method of the present invention; d is not particularly limited, and conventionally known equipment can be used.

Such equipment can be operated under the conditions described above to fluorinate the surface of rubber products. per lζ to be fluorinated, m
It is necessary to completely remove oxygen from the 11J container and rubber products. As a method for removing oxygen, a dense ρ-1 valley vessel containing a rubber product is used at u, 1 Torr to 1″l'orr.
After the container is evacuated under a positive pressure of 0.000, the container is filled with an inert gas such as helium, and the inert gas is further heated to 0.000. ITorr
Oxygen in the container can be removed by evacuation at a positive pressure of 1 Torr. - If oxygen cannot be removed by the evacuation operation twice, the above operation may be performed multiple times.

After surface treatment of rubber products, the sealed container is heated to 0.1 Torr.
After exhausting the processing gas at a positive pressure of 1 Torr and filling the container with inert gas to completely remove unreacted fluorine gas and hydrogen fluoride residue, the rubber products are removed from the closed container. is taken out. When forming a relatively thick fluorinated layer on the surface of a rubber product using low-concentration fluorine gas, a fluorinated layer of the desired thickness is formed by performing the fluorine gas filling and discharging operations multiple times. be able to.

The method of the present invention has superior operability compared to conventional surface treatment methods for rubber products, and since only the outermost layer is fluorinated, it does not impair the properties of the rubber and the surface is non-smooth. It has the characteristics of viscosity, slipperiness, and surface stain resistance, and is expected to expand the use of rubber products and reduce costs. It is extremely large.

Next, the method of the present invention will be explained in more detail with reference to Examples.

Example 9 A rubber plate with a diameter of 20M and a length of sarrrm made from a vulcanizate using 95% isoprene rubber as a substrate was housed in 11 Monel metal containers, and the sealed container was heated to I Torr.
After evacuating to a positive pressure of I Torr and then filling with helium gas, the helium gas was evacuated to an autogenous pressure of I Torr - and the closed vessel was sealed. Next, a mixed gas containing 5 ml (trough h1) of fluorine gas and 95% (by volume) helium gas was introduced into the closed container until atmospheric pressure was reached.The reaction time was The starting point was when the inside of the container reached atmospheric pressure. After aerating the rubber plate in the mixed gas for a predetermined time, the mixed gas in the scale container was evacuated at a pressure of 1°l'orr, and helium was removed. After purging with gas, the rubber plate was taken out from the container, the surface of the rubber plate was observed with bsaA, and the tensile force based on the frictional force was added by t1tII.The results are shown in Figure 1.

The tensile force based on the vibrational force Cζ between the rubber plate whose surface was fluorinated and the polyethylene film was measured as follows. A polyethylene film with a thickness of 0.11 rJn and a width of 5 Wn is spread across a rubber plate at 90 degrees, and a spring scale is attached to the upper end of the film, and a 5 g square is placed on the lower end of the film. The film was pulled and the tension caused by the friction and force of the rubber plate when the film started to slip was determined.

-1 Licensed hrt 1 person Kuraray Co., Ltd. (T,'ft month agent patent attorney Ken Honda 1)

Claims (1)

[Claims] 1. By exposing a rubber product to 0.1 to 20% fluorine gas diluted with an inert gas, at least 0.002 carbon atoms per one carbon atom on the surface of the rubber product are removed. A method for surface treatment of rubber products characterized by bonding fluorine atoms.