JP2002161154A - Method for modifying rubber surface and rubber wiper blade made by using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for modifying a rubber surface which can reduce a friction coefficient of the rubber surface, and provide a rubber wiper blade made by using it. SOLUTION: A valcanized rubber to which an activating treatment is given in advance is immersed in an isocyanate treatment solution, then the surface of the valcanized rubber is cured for surface modification.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber surface modification method capable of reducing the friction coefficient of a rubber surface and a rubber wiper blade using the same.

[0002]

2. Description of the Related Art A member used for a wiper for an automobile is formed by sliding the surface of the member with an object (glass or the like).
It functions to remove rainwater, dust and the like. A member made of rubber is usually used for such an automobile wiper.

In general, since a member made of rubber has poor surface slipperiness, it is preferable that the coefficient of friction is reduced so as not to cause creaking noise and uneven wiping during use. For this reason, various attempts have been made to reduce friction, such as, for example, bloom, bleed, laminating, lubricant, resin, physical treatment such as kneading of fibers, acid, Chemical treatment with various chemicals such as alkalis and halogens can be mentioned. Above all, halogen treatment such as chlorination treatment is common.

[0004] By performing the above chlorination treatment, the initial friction coefficient is reduced, but when used for a long period of time, there is a problem that the friction coefficient becomes high and the slidability deteriorates. That is, since the chlorination treatment is a method of modifying the rubber surface by deteriorating the rubber with chlorine, the modified rubber surface gradually drops as it comes into sliding contact with the object (glass or the like),
There is a problem that the friction coefficient becomes high and the reduced friction coefficient cannot be maintained for a long time.

In recent years, it has been pointed out that harmful substances such as dioxin may be generated during incineration of chlorine-containing compounds, and dehalogenation is also required for members used for automobile wipers. The chlorinated member has a problem in that halogenous harmful substances are generated at the time of incineration disposal.

[0006]

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a method for modifying the surface of rubber, which can reduce the coefficient of friction of the rubber surface, and a rubber wiper blade using the same. It is assumed that.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method for modifying the surface of rubber, in which a vulcanized rubber which has been previously activated is impregnated with an isocyanate treatment solution, and then the surface of the vulcanized rubber is cured. is there. Hereinafter, the present invention will be described in detail.

[0008] In the rubber surface modification method of the present invention,
It is necessary to previously activate the vulcanized rubber. The vulcanized rubber used in the present invention is not particularly limited. For example, natural rubber (NR), isoprene rubber (I
R), butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), chloroprene rubber (CR), fluoro rubber (FKM), butyl rubber (IIR), ethylene-propylene copolymer Polymerized rubber (EPM), ethylene-propylene-diene terpolymer rubber (EPDM), hydrogenated nitrile rubber (hydrogenated NBR), silicone rubber, epichlorohydrin rubber (CO, ECO), polysulfide rubber (T),
A vulcanizing agent, a matrix component such as urethane rubber (U),
Vulcanization accelerators, softeners, anti-aging agents, fillers, silane coupling agents, silica, carbon black, and other additives blended by conventional methods such as press vulcanization. Can be mentioned.

As the above-mentioned activation treatment, a known activation treatment can be appropriately used, and is not particularly limited. Examples of the activation treatment include ultraviolet treatment, plasma treatment, electron beam treatment, radiation treatment, ion beam treatment, and the like. Corona discharge treatment or the like is preferably used. By performing such activation treatment, reaction sites such as hydroxyl groups are generated on the surface of the vulcanized rubber.

[0010] In the case of performing the ultraviolet treatment as the activation treatment, the conditions are not particularly limited and can be appropriately determined depending on the irradiation target of the ultraviolet light.
The surface of the vulcanized rubber can be activated by irradiating ultraviolet rays having a wavelength of about 450 nm for 1 to 10 minutes.

In the rubber surface modification method of the present invention,
Next, the vulcanized rubber that has been previously activated is impregnated with the isocyanate treatment liquid. The isocyanate treatment liquid is obtained by dissolving an isocyanate compound in a solvent.

The isocyanate compound is not particularly limited as long as it has two or more NCO groups.
For example, tolylene diisocyanate (2,4, 2,6
Isomer), 4,4'-diphenylmethane diisocyanate (pure MDI, polymeric MDI), m-phenylene diisocyanate; tetramethylene diisocyanate, hexamethylene diisocyanate; 4,4 ', 4 "-triphenylmethane triisocyanate, 2,4', 4 "-
Examples thereof include biphenyl triisocyanate, 2,4,4 "-diphenylmethane triisocyanate, modified products thereof, and polymers thereof. Among them, 4,4'- Those having a relatively low molecular weight, such as diphenylmethane diisocyanate and tolylene diisocyanate, are suitably used.These isocyanate compounds may be used alone or in combination of two or more.

The concentration of the isocyanate compound in the above-mentioned isocyanate treatment solution is not particularly limited.
It is preferably 0% by weight. If it is less than 1% by weight,
In some cases, the surface of the vulcanized rubber is not sufficiently modified, and the coefficient of friction does not decrease. On the other hand, if it exceeds 50% by weight, the rubber hardness after the modification becomes too large, and the rubber elasticity may be extremely lowered. More preferably 5 to 30% by weight
It is.

The solvent is not particularly limited as long as it dissolves the isocyanate compound, and examples thereof include n-butyl acetate, ethyl acetate, toluene, MEK, acetone and the like.

In the rubber surface modification method of the present invention,
Further, a step of curing the surface of the vulcanized rubber is performed. A reaction site such as a hydroxyl group formed by the activation treatment and the isocyanate compound react with each other to form a cured layer on the surface of the vulcanized rubber by crosslinking and curing.

The method for curing the surface of the vulcanized rubber is not particularly limited, and examples thereof include a method of treating at a high temperature in an oven. When the curing treatment is performed by such a method, the curing treatment temperature is not particularly limited, but is preferably 50 to 250 ° C. 50
If the temperature is lower than 0 ° C, the isocyanate compound may not be sufficiently cured, and the surface friction coefficient of the vulcanized rubber may not be reduced. On the other hand, if the temperature exceeds 250 ° C., the entire vulcanized rubber may be thermally aged. More preferably 70 to 2
00 ° C.

The vulcanized rubber treated by the method for modifying the surface of rubber of the present invention has a hardened layer having a considerable thickness on the surface, which is strongly crosslinked, and has the flexibility and the flexibility of the vulcanized rubber inside. Since it has an elastic layer that retains elasticity, as a whole, it has excellent properties such as wear resistance, low compression set, rebound resilience and heat resistance.

By using the rubber surface modification method of the present invention, for example, the surface of a rubber wiper blade can be modified. According to the method for modifying the surface of rubber of the present invention, a cured layer can be formed on the surface of the vulcanized rubber, and furthermore, the formed cured layer has a sufficient thickness. Rubber wiper blades for automobiles do not have a problem that the coefficient of friction does not increase even after long-term use and the slidability deteriorates. A rubber wiper blade obtained by using the rubber surface modification method of the present invention is also one of the present invention.

The rubber surface modification method of the present invention is not particularly limited, and may be used not only for rubber wiper blades for automobiles, but also for rubber rollers which require good sliding properties and abrasion resistance. It is also suitably used for various members such as rubber belts, rubber hoses, and sealing materials such as lip seals.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

<Preparation of Wiper Blade Rubber> A composition having the composition shown in Table 1 was kneaded and vulcanized at 150 ° C. for 10 minutes to prepare an untreated wiper blade rubber.

[0022]

[Table 1]

The obtained untreated wiper blade rubber was subjected to an isocyanate treatment in Examples 1 to 3 and a chlorination treatment in Comparative Example 2 as described below.
Each of the treated wiper blade rubbers was subjected to an evaluation test. In Comparative Example 1, an evaluation test was performed using untreated wiper blade rubber as it was.

Examples 1 to 3 <Isocyanate treatment> Crude MDI was dissolved in n-butyl acetate such that the solid content concentration was as shown in Table 2, to prepare an isocyanate treatment solution. 365 nm
After irradiating the untreated wiper blade rubber with ultraviolet light having a wavelength of 10 mm for 10 minutes, the wiper blade rubber was immersed in the above isocyanate treatment liquid for 10 minutes. Next, the wiper blade rubber is dried at room temperature for 10 minutes,
Thereafter, the sample was cured in an oven at 150 ° C. × 10 minutes to prepare a sample for evaluation.

[0025]

[Table 2]

Comparative Example 2 <Chlorination treatment> 3 g of powder exposed to 2 kg of water and 5 g of 12N hydrochloric acid
and chlorinated solution was prepared. An untreated wiper blade rubber was immersed in the chlorination solution for 10 minutes to perform a surface treatment, thereby preparing a sample for evaluation.

<Evaluation Items and Test Methods> The friction coefficient at the initial stage and after sliding 10,000 times on the dry glass surface was measured. The measurement was performed using a friction coefficient meter (HEIDON-14 manufactured by Shinto Kagaku Co., Ltd.)
D). The results are shown in Table 3.

[0028]

[Table 3]

As is clear from the results shown in Table 3, the product of the example had a lower coefficient of friction than the product of the comparative example. Moreover, the example product was able to maintain a low friction coefficient even after sliding 10,000 times. In contrast, the chlorinated wiper blade rubber of Comparative Example 2 showed an effect of reducing the friction coefficient immediately after the surface treatment, but the friction coefficient was significantly increased after 10,000 sliding operations. The product of Example 3 had a higher initial friction coefficient than that of Comparative Example 2, but showed little change in the coefficient of friction even after 10,000 slides, and had lower friction properties after long-term use than the product of Comparative Example 2. Was excellent.

[0030]

According to the present invention, the surface of the vulcanized rubber can be modified by forming a cured layer having a sufficient thickness on the surface of the vulcanized rubber. A vulcanized rubber having a low coefficient of friction and excellent abrasion resistance can be obtained.

Claims (4)

[Claims] 1. A method for modifying the surface of rubber, comprising impregnating a vulcanized rubber which has been subjected to an activation treatment in advance with an isocyanate treatment liquid, and then curing the surface of the vulcanized rubber. 2. The method according to claim 1, wherein the activation treatment is at least one selected from the group consisting of an ultraviolet treatment, a plasma treatment, an electron beam treatment, a radiation treatment, an ion beam treatment, and a corona discharge treatment. Rubber surface modification method. 3. A rubber wiper blade obtained by using the method for modifying a surface of rubber according to claim 1. 4. A rubber wiper blade obtained by using the method for modifying a surface of rubber according to claim 2.