JP2000044708A - Surface-treatment of rubber article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for surface-treating a rubber article to impart nonstickiness, lubricity, and other barrier effects thereto which method comprises surface-treating the rubber article in an unvulcanized or vulcanized state with a treatment solution prepared by mixing an aqueous formic acid or acetic acid solution having a specified concentration with hydrogen peroxide in an amount corresponding to a specified molar ratio of the acid and epoxidizing the surface layer of the product. SOLUTION: An aqueous solution containing 1-20 wt.% organic acid such as acetic acid or formic acid is mixed with hydrogen peroxide in an amount corresponding to a hydrogen peroxide/organic acid molar ratio of 1.5-20 to prepare a peracetic acid or performic acid treatment solution having a peroxy acid concentration of 1-4 wt.%. Next an unvulcanized or vulcanized rubber article comprising a natural rubber or a synthetic diene rubber is surface-treated by immersion in the treatment solution to epoxidize a part of the double bonds on the surface layer of the article to thereby obtain a surface-treated article improved in abrasion resistance, chemical resistance, gas barrier properties, wet grip performances, surface gloss, and coating film transparency. The organic peroxy acid is represented by the formula: RCO3H and is exemplified by performic acid, peracetic acid, perbenzoic acid, or perphthalic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for imparting non-adhesion or lubricity to the surface of a rubber product.

[0002]

2. Description of the Related Art Conventionally, as a method for imparting a barrier effect such as non-adhesiveness, lubricity and blooming prevention to the surface of a rubber product, (1) a halogen such as chlorine is added and reacted.
(2) powder of silica, talc, corn starch, etc. (3) silicone, fluorine resin, urethane resin,
Surface coating with hydrogel polymer, etc., (4) Surface modification by specific organic acid, inorganic acid, plasma etching, corona discharge treatment, etc., (5) Surface cleaning by solvent treatment, (6) Hot water, slightly alkaline, acid There is surface extraction with a solution.

[0003]

SUMMARY OF THE INVENTION
Although the method (1) is effective for imparting non-adhesiveness and lubricity, the problems of deterioration of the working environment due to toxic gas, treatment of wastewater, and separation of halogen after commercialization become problems. Have. The above method (2) is often used as the most common means, but it has been pointed out that there is a problem of dust contamination during the work process and during use, especially in the medical field where powder contamination causes various infectious diseases. In the field of precision machines and electronic components, there is a problem that defective products are caused, and in a process such as bonding, defective bonding is caused. In order to cope with these problems, there has been adopted a method of removing powder by washing before use. However, it is difficult to completely remove powder, and dust-free is an important problem.

In the above method (3), since the surface of the rubber body is coated with a different kind of polymer or the like through a complicated process, the original properties and physical properties of the body itself affect the rubber body, or the rubber body is dropped. There is a problem that there is a possibility that the operation may be performed. Also, in the above (4), there is a problem that the processing equipment becomes large and the processing steps become complicated, and the methods (5) and (6) cannot be expected to have a sufficient effect for the purpose of imparting non-adhesiveness and lubricity. . Furthermore, in recent years, the necessity of separation due to the disposal or incineration of materials has also raised a problem that the use of halogens and surface complexing with different polymers leads to an increase in total cost.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and the method comprises adding hydrogen peroxide to an aqueous solution of peracid, particularly acetic acid or formic acid. To produce a peracetic acid or formic acid solution, which is used to epoxidize a portion of the double bond of natural rubber and other diene-based synthetic rubbers as represented by the following formula: This imparts non-adhesiveness, lubricity and other barrier effects to the surface of the rubber product. As a method of epoxidizing a double bond between carbon atoms, it is known that a peracid of an organic compound is used.
Expressed as CO3 H. For example, there are formic acid, peracetic acid, perbenzoic acid, perphthalic acid and the like.

[0006]

Embedded image

[0007]

Embodiments of the present invention will be described below.

The surface layer is uniformly epoxidized by immersing a film prepared from the following natural rubber latex vulcanization compounding solution into a treatment solution obtained by adding hydrogen peroxide to an aqueous solution of acetic acid or formic acid. The obtained rubber film was obtained.

Latex formulation for immersion Concentrated natural rubber latex 100 Dry parts by weight S 1 Dry parts by weight ZnO 1 Dry parts by weight Vulcanization accelerator PX 0.8 Dry parts by weight Antioxidant 1 Dry parts by weight

[0010]

Example 1 Treatment liquid formulation Formic acid (98%) 4% by weight Hydrogen peroxide solution (35%) 16% by weight Distilled water Remainder

[0011]

Example 2 Treatment liquid formulation Formic acid (98%) 10 parts by weight Hydrogen peroxide solution (35%) 40 parts by weight Distilled water Remainder

[0012]

Example 3 Treatment liquid formulation Formic acid (98%) 1.4 parts by weight Hydrogen peroxide solution (35%) 44.0 parts by weight Distilled water Remainder

[0013]

Example 4 Treatment liquid formulation Acetic acid (98%) 5 parts by weight Hydrogen peroxide solution (35%) 20 parts by weight Distilled water Remainder

[0014]

[Comparative Example 1] Treatment liquid formulation Sodium hypochlorite (15% Cl) 2 parts by weight Concentrated hydrochloric acid 1 part by weight Distilled water balance

[0015]

Comparative Example 2 A talc powder was applied to the surface of a rubber film.

[Treatment Step] A rubber film containing the above natural rubber latex was produced by the steps shown in Table 1.
4 and Comparative Example 1, and Comparative Example 2
And a rubber coating sample was obtained.

[0017]

[Table 1] Table 2 shows Examples 1-4, Comparative Examples 1-2, and untreated surface treatment conditions and results, and Table 3 shows Examples 1, Comparative Example 2, and untreated physical properties.

[0018]

[Table 2] In Table 2 above, in the test method for slipperiness, a sample was fixed on a table whose inclination angle could be freely changed, a 2 g weight was placed on the sample, and the angle at which the sample slipped off was measured. The adhesion test method is based on JIS Z0237 rolling ball tack test. The number of days of whitening of the surface is the number of days until the rubber surface is whitened in ventilation, shade exposure, 30 ° C. and 70% humidity.

[0019]

[Table 3] In the above embodiment, the rubber product is immersed in an aqueous solution of peracid for surface treatment. For example, an aqueous solution (hydrogen peroxide solution) obtained by adding hydrogen peroxide to an acetic acid or formic acid solution is used. A method of epoxidizing a surface layer of a rubber product by applying or spraying on the surface may be adopted.

[0020]

As described above, according to the present invention, the double bond portion of the molecule on the surface of natural rubber and other diene-based synthetic rubber products is epoxidized with a peracid so that a relatively simple treatment equipment can be obtained. The non-adhesiveness, lubricity, and other barrier effects of the rubber product surface could be imparted without compromising the inherent elasticity, elongation, tensile strength, and the like of the rubber product, using inexpensive raw materials.

Further, according to the method of the present invention, there is no generation of harmful gas or contamination by dust in the manufacturing process, and the working environment can be remarkably improved.

Furthermore, the epoxidation of the rubber product surface layer enhances abrasion resistance, chemical resistance, gas permeation resistance, wet gripping property, surface gloss, transparency of the film and continuity of their aesthetic characteristics. Etc. were obtained.

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[Procedure amendment]

[Submission date] June 23, 1999 (1999.6.2
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

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[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

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[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and comprises adding hydrogen peroxide to an aqueous solution of peracid, especially acetic acid or formic acid.
Peroxidic acid or formic acid solution
By using a treatment liquid obtained by adding hydrogen water, a part of the double bond of natural rubber and other diene-based synthetic rubbers is epoxidized as shown in the following formula to obtain the surface of the rubber product. To impart non-adhesiveness, lubricity, and other barrier effects to the film. It is known that a peracid of an organic compound is used as a method of epoxidizing a double bond between carbon atoms,
The general formula is represented by RCO3H. For example, there are formic acid, peracetic acid, perbenzoic acid, perphthalic acid and the like. Simply peracid, eg
For example, an aqueous solution of peracetic acid (for example, an aqueous solution of about 1 to 4%)
In the process of immersing and overheating rubber products,
Non-adhesive without giving sufficient lubricity to the surface
Stay or clean the rubber surface in aqueous solution
May increase the adhesiveness. 4% or more peracid
If you try to react efficiently at the concentration, cracks on the rubber surface
Phenomena such as this occur, and the physical properties of rubber products are greatly reduced.
As in the present invention described above, the presence of a peracid and a peroxide depends on the rubber surface.
Is important in the reaction stage leading to epoxidation of
Incorporate excess peroxide in a range of molar ratios
Allows the minimum amount of organic acids to act efficiently,
Or even in the presence of more peracid,
Epoxy surface layer of rubber products without deteriorating physical properties
To impart non-stick, lubricity and other barrier effects
can do. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] September 29, 1999 (1999.9.2)
9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

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[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems described above, acetic acid
Or an aqueous solution obtained by adding hydrogen peroxide to an aqueous solution of formic acid.
The concentration of the aqueous solution of acetic acid or formic acid is 1 to 20%
And the molar ratio of hydrogen peroxide / acid is in the range of 1.5 to 20
By using a processing solution that is, as shown in the following formula, by epoxidizing a part of the double bond of natural rubber and other diene-based synthetic rubber, non-adhesive to the surface of the rubber product,
It imparts lubricity and other barrier effects. As a method of epoxidizing a double bond between carbon atoms, it is known that a peracid of an organic compound is used.
Expressed as CO3 H. For example, there are formic acid, peracetic acid, perbenzoic acid, perphthalic acid and the like. In a treatment in which a rubber product is simply immersed in an aqueous solution of a peracid, for example, peracetic acid (for example, an aqueous solution of about 1 to 4%) and heated, the rubber product becomes non-adhesive without providing sufficient lubricity to the surface. The rubber surface may remain or be washed in an aqueous solution, and the tackiness may be increased. In addition, if the reaction is attempted efficiently at a peracid concentration of 4% or more, phenomena such as cracks occur on the rubber surface, and the physical properties of the rubber product are greatly reduced. As in the present invention, by adding an excess of peroxide to acetic acid or formic acid in a certain range of molar ratio, a minimum amount of organic acid can be efficiently actuated, and 1 to 4% or more of excess organic acid can be used. Even in the presence of an acid, the surface layer of the rubber product can be epoxidized without deteriorating the physical properties of the rubber product, and non-adhesiveness, lubricity, and other barrier effects can be imparted.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takashi Sugai 3318-2 Nakatsu, Aikawa-cho, Aiko-gun, Kanagawa Prefecture F-term in Retex Inc. (reference) 4F073 AA05 AA10 AA17 BA04 EA01 EA31 EA36 EA59 EA63 HA13

Claims (4)

[Claims] 1. An unvulcanized or vulcanized rubber product is surface-treated with an aqueous solution in the presence of a peracid to epoxidize a rubber product surface layer and impart non-adhesiveness, lubricity, and other barrier effects. A method for treating a surface of a rubber product. 2. The method for treating a rubber product surface according to claim 1, wherein the peracid is an aqueous solution obtained by adding hydrogen peroxide to an aqueous solution of acetic acid or formic acid, or perbenzoic acid, perphthalic acid, formic acid, or peracetic acid. A method for treating a surface of a rubber product, characterized by using: 3. The method for treating a surface of a rubber product according to claim 2, wherein the concentration of the aqueous solution of acetic acid or formic acid is from 0.1 to 0.1.
50% by weight, preferably 0.5 to 20% by weight, and a peroxide / acid molar ratio of 0.3 to 50, preferably 1.0
35. A method for treating a surface of a rubber product, which is in the range of from 30 to 30. 4. The method for treating a surface of a rubber product according to claim 2, wherein the peracids are formic acid, peracetic acid, perbenzoic acid,
A surface treatment method for a rubber product, wherein the concentration of perphthalic acid is in the range of 0.1 to 50% by weight, preferably 0.5 to 30% by weight.