JPH0738967B2 - Surface treatment method for rubber products - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for surface-treating a rubber product composed 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 of 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 work environment and increases the cost of equipment due to the use of high energy. There was a problem.

Further, regarding 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 adhesion of resin 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 resin can adhere to the surface, but the adhesive force There was a drawback that was weak

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 the part is easily peeled off and removed, which makes it difficult to use for a long time.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and a means thereof is a modified urethane emulsion in which at least polybutadiene polyol is used as a polyol on the surface of a rubber main body. Is applied to form a dry film.

[0008]

EXAMPLES Examples of the present invention will be described. The rubber main body is various rubber products made of natural rubber and diene-based synthetic rubber well known in the technical field of this kind, such as finger cots, medical devices (ice packs). , Draped bag, 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 A modified urethane emulsion using at least polybutadiene polyol as a polyol is applied to both the inner and outer surfaces by an arbitrary method such as coating, spraying or dipping, and dried to form a film.

The composition of the urethane emulsion comprises a copolymer of polyols, diisocyanates, chain extenders (polyhydric alcohols, polyhydric amines),
Considering factors such as hydrophilicity, high reactivity, adhesion, and low coefficient of friction as factors selected as the monomer for the modified urethane, good-performance polyols include poly-ε-caprolactone, polyhexamethylene carbonate, and polybutadiene. Examples thereof include polyols and silicone polyols.
Among them, particularly high-performance polyols are polyhexamethylene carbonate, polybutadiene polyol, and silicone polyol, and in the present invention, at least high-performance polybutadiene polyol is used as the polyols. As diisocyanates, tolylene diisocyanate, 4-4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, 4
-4'-methylenebis (cyclohexyl isocyanate), isophorone diisocyanate and the like. The chain extender is polyhydric alcohol such as ethylene glycol,
1,4 butanediol and the like, and polyvalent amines include isophoronediamine, 4-4′-diphenylmethanediamine, hydrazine and the like. Furthermore, it is possible to use the polybutadiene polyol as the basic polyol of the copolymer in combination with other ordinary polyols, and to blend one or more modified urethanes containing at least polybutadiene polyol as the polyols. It is also possible to use one.

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

The modified urethane emulsion using at least polybutadiene polyol as the polyols has a composition very close to that of the main body of the rubber product, and therefore has much better compatibility than conventional urethanes. Therefore, it firmly 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 catalysts, 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 containing 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 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 with 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 main body is coated with a modified urethane emulsion containing at least polybutadiene polyol as a polyol to form a dry film. Therefore, the non-adhesiveness and the physical properties (strength) are improved and the lubricity is improved. Of course, it is possible to obtain those improved, and it is extremely simple as compared with the conventional method without requiring pretreatment, and there is no peeling during use and elongation. .

That is, since the modified urethane emulsion using at least polybutadiene polyol as the polyol has a very high compatibility with the diene rubber, compared with the conventional urethane, acrylic and inert silicone emulsions having a high polarity. As a result, the adhesive strength is improved, and a strong film can be formed permanently on the surface of the rubber product, and since powder or the like is not used, it is not contaminated and is not removed at the time of use.

Claims (1)

[Claims] 1. A surface of a rubber body is coated with a polyol.
A method for surface treatment of a rubber product, which comprises applying a modified urethane emulsion containing at least polybutadiene polyol to form a dry film.