JPH05123641A - Surface treatment of rubber product - Google Patents

Abstract

PURPOSE:To impart nonstickiness and lubricity to the surface of a rubber prod uct by coating the surface of the rubber body with a surface treating agent made of a modified urethane emulsion and forming a coating film by drying. CONSTITUTION:The surface of the rubber body of a rubber product is coated with a surface treating agent made of a modified urethane emulsion and a coating film is formed by drying. Since the modified urethane emulsion has very high compatibility with diene rubber, adhesive strength is enhanced as compared with the case of an ordinary urethane, acrylic or silicone emulsion and a tough coating film is permanently formed on the surface of the rubber product. The nonstickiness and physical property (strength) of the rubber product are improved, lubricity is imparted and exfoliation is not caused even at the time of use and by elongation.

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 a rubber product made of natural rubber and a diene-based synthetic rubber, and more particularly to a method for obtaining a rubber product provided with non-adhesion and lubricity.

[0002]

2. Description of the Related Art Conventionally, as a method for treating the surface of a rubber product composed of natural rubber and diene-based synthetic rubber, (1) chlorine is added to the surface (chlorination), (2) surface degreasing by solvent treatment, (3) Surface oxidation such as strong acid treatment, plasma treatment, corona treatment, (4) surface roughening by blast treatment, (5)
There were adhesion of powder of silica, talc, starch, and (6) adhesion of resin such as silicone and fluororesin.

[0003]

However, these methods are labor-intensive, and the use of harmful substances and strong oxidants lowers the working environment and increases the cost of equipment due to the use of high energy. There was a problem.

Further, with respect to the chlorinated product, water marks may remain on the rubber product depending on the drying condition after washing, and the chlorinated product may harden the surface of the rubber to cause minute cracks. There was also a problem.

Regarding the resin adhesion to the surface, the natural and synthetic rubbers, which are the raw materials of these rubber products, have few functional groups because of their composition, so that the resins can adhere to the surface, but the adhesive force There was a defect that was weak

[0006] Silicone oil and powders have the drawback that they are removed from the rubber surface after a short period of use, giving a sticky feeling, and other synthetic resins also have a weak adhesive force and thus extend rubber products. In such a case, cracks are formed and are easily peeled off and partially removed, which makes it difficult to use for a long time.

[0007]

The present invention has been made in view of such circumstances, and means for applying a modified urethane emulsion to the surface of a rubber main body,
It is to provide a dry film.

[0008]

EXAMPLES Examples of the present invention will be described. The rubber main body is made of various kinds of rubber products made of natural rubber and diene-based synthetic rubber, which are well known in the technical field of this kind, such as finger cots, medical devices (ice packs). , Drapeback, catheter balloon, urethral catheter), tube, glove, packing rubber, rubber band, etc., which are obtained by well-known manufacturing methods such as dipping method and extrusion method, and the surface thereof, that is, the outer surface or inner surface or The modified urethane emulsion is coated on both the inner and outer surfaces by an arbitrary method such as coating, spraying, dipping, and dried to form a film.

The composition of the modified urethane emulsion is composed of a copolymer of polyols, diisocyanates and chain extenders (polyhydric alcohols, polyhydric amines), and factors selected as monomers include Hydrophilic,
Considering high reactivity, adhesion, low coefficient of friction, etc., good performance polyols include poly-ε-caprolactone,
Examples of the polyisocyanate include polyhexamethylene carbonate, polybutadiene polyol, and silicone polyol, and the diisocyanates include tolylene diisocyanate and 4-
4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, 4-4'-methylenebis (cyclohexyl isocyanate), isophorone diisocyanate and the like. Further, the chain extender is polyhydric alcohol such as ethylene glycol and 1,4 butanediol,
As polyvalent amines, isophoronediamine, 4-4'-
Examples include diphenylmethanediamine and hydrazine. Particularly high-performance polyols are polyhexamethylene carbonate, polybutadiene polyol, silicone polyol and the like. It is also possible to use these as the basic polyol of the copolymer in combination with other polyols, that is, to use the modified polyol alone or a blend of these other modified urethanes.

Further, in the present invention, it is necessary to adjust the solution concentration of the modified urethane emulsion so as to be suitable for each rubber body, and the range of 0.1 to 10% is suitable, and 0.5 to 7 for ordinary rubber products. % Can be more effective.

Since the composition of the above-mentioned modified urethane emulsion is very close to that of the main body of the rubber product, the compatibility is far better than that of the conventional urethane. Therefore, it adheres to the surface of the rubber product body.

In order to improve the solvent resistance, heat resistance and water resistance of such an emulsion, water-soluble melamine, epoxy resin or the like is used as a cross-linking agent, organic amines or ammonium salts are used as a catalyst, and rubber is used. In order to improve the lubricity of polybutadiene-based urethane, which has excellent adhesiveness, epoxy-modified silicone is added as a surface treatment agent, and a good lubricant such as silicone powder, urethane powder, polyethylene wax, fluorine It is also possible to add resin powder or the like, and the rubber body is dipped in this surface treatment agent, or the surface treatment agent is sprayed or coated on the surface.

An example of the formulation of the treatment liquid of this surface treatment agent is as follows: 100 parts by weight of the modified urethane emulsion (40%), 300 to 40,000 parts by weight of water, and 1 to 10 parts of the water-soluble epoxy resin.
Appropriate amount of parts by weight and lubricant. The coating amount should be taken into consideration when it is dried to form a film, but it should be formed as thin as possible so as not to change the texture of the rubber product.

Next, specific embodiments and comparative examples (conventional methods) will be described in detail. Example 1 and Comparative Example 1 A rubber tube was formed from the following natural dry rubber compound by an extrusion method and processed by the steps shown in Table 1. The compounding example of the surface treatment agent in Example 1 is 100 parts by weight of the modified urethane emulsion (40% urethane solid content) (40 parts by weight of polybutadiene-based urethane emulsion and 60 parts by weight of polycarbonate-based urethane emulsion) and 30 parts of water.
0 parts by weight, 4 parts by weight of a water-soluble epoxy resin (epoxy crosslinking agent), and 1 part by weight of silicone powder were added.

Natural rubber 100 parts by weight S 2 parts by weight ZnO 3 parts by weight TET 1 part by weight TMT 0.5 part by weight Stearic acid 1 part by weight Anti-aging agent 1 part by weight

[0016]

[Table 1]

Example 2 and Comparative Example 2 Rubber gloves are molded in the following natural rubber latex formulation by the dipping method, that is, by the steps shown in Table 2. The surface treatment agent in Example 2 has the same composition as in Example 1.

Natural rubber latex (DRY) 100 parts by weight S 1 part by weight ZnO 1 part by weight Dithiocarbamate vulcanization accelerator 0.8 parts by weight Antioxidant 1 part by weight Stabilizer proper amount

[0019]

[Table 2]

Example 3 A rubber film prepared by blending the natural rubber latex shown in Example 2 above was prepared, and the physical properties and performance tables of the rubber film having the surface treatment agent and the untreated rubber film in Example 1 are shown in Table 3. Show.

[0021]

[Table 3]

[0022]

According to the present invention, the surface of the rubber body is coated with the modified urethane emulsion to form a dry film, so that the non-adhesiveness and the physical properties (strength) are improved and the sliding property is imparted. An improved product is obtained, and it is extremely simple as compared with the conventional method without requiring pretreatment, and is free from peeling during use and elongation.

That is, since the modified urethane emulsion has extremely high compatibility with the diene rubber, the adhesive strength is improved as compared with conventional urethane, acrylic and inert silicone emulsions having high polarity.
A strong film can be formed permanently on the surface of the rubber product, and since no powder or the like is used, it is not contaminated and is not removed during use.

Claims (1)

[Claims] 1. A method for surface treatment of a rubber product, which comprises applying a modified urethane emulsion to the surface of a rubber body to form a dry film.