JPS62212442A - Rubber molding having coated surface - Google Patents

Abstract

PURPOSE:To provide the titled molding having excellent sealing properties and non-stickiness, by coating the surface of a molding composed of a rubber material with a mixture of a solid lubricant and fluororubber to form a film. CONSTITUTION:5-95wt%, pref. 20-80wt% solid lubricant (a) (e.g., powdered polytetrafluoroethylene) is mixed with 5-95wt%, pref. 20-80wt% fluororubber (b) (e.g., a copolymer rubber composed of 40-50mol% of propylene, 50-60mol% of tetrafluoroethylene and 0.2-5mol% of glycidyl vinyl ether) and optionally, 0.1-10pts.wt. [per 100pts.wt. component (b)] vulcanizing agent (c) to obtain a mixture (B). 5-50wt% component B is dispersed in an org. solvent (e.g., ethyl acetate) to obtain a coating soln. Optionally, a primer is applied to the surface of a molding (A) molded from a rubber material (e.g., silicone rubber). The soln. is then applied thereto in such a coating weight as to give a film having a thickness of 5-1,000mu, composed of the component B.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to surface-coated rubber molded articles.

More specifically, the present invention relates to a rubber molded article that is used as a dynamic sealing material and has a coating that makes the surface of the molded article non-adhesive.

[Conventional technology]

Many types of dynamic sealing materials are molded from rubber materials, but in the case of sealing materials that repeatedly come into contact and non-contact, such as valve seats, it is generally not possible to reduce adhesion while maintaining sealing performance. was difficult.

Various proposals have been made to improve the surface adhesion of rubber molded products, but when used for surface treatment of dynamic sealing materials, all of them have the following drawbacks and are unsatisfactory. This is not a method that can be used.

(1) A method of roughening the surface of a rubber molded product. This method does not have a large anti-stick effect. (2) A method of curing the surface of a rubber molded product with chemicals. This method cannot maintain airtightness with the mating material. 3) Method of forming a resin-based film on the surface of a rubber molded product Again, airtightness with the mating material cannot be maintained (4) Method of forming a rubber-based film on the surface of a rubber molded product Except for fluororubber, high temperature It cannot be used in an atmosphere that exceeds the heat resistance temperature of the coated rubber material [Problem to be solved by the invention] The present inventor has discovered that when a rubber molded product used as a dynamic sealing material is brought into contact with a material, After various studies in search of a method to make the surface of rubber molded products non-adhesive while maintaining sealability (airtightness) with the mating material, we formed a solid lubricant-fluororubber mixture coating on the surface of the molded product. It has been found that this problem can be effectively solved by doing so.

[Means for Solving the Problems] and [Operations] Accordingly, the present invention relates to a surface-coated rubber molded article, in which the surface of the molded article is coated with a mixture coating of a solid lubricant and fluororubber. It will be done.

The rubber molded product on which the film is formed is fluororubber.

Including rubbers with excellent heat resistance such as silicone rubber, ethylene-propylene (-diene) based rubbers.

It is a molded product made from chloroprene rubber, acrylic rubber, etc., and is generally molded into the shape of various sealing materials including dynamic sealing materials.

As the solid lubricant which is one of the components forming the mixture film, for example, polytetrafluoroethylene, graphite, molybdenum disulfide, graphite fluoride, hard polyethylene, silicone resin, etc. are used, and preferably polytetrafluoroethylene is used. It will be done. The polytetrafluoroethylene used may be either fired or unfired, and may be fine powder, molding powder, or telomerized wax.

Examples of the fluororubber, which is the other component that forms the mixture film together with these solid lubricants, include propylene-tetrafluoroethylene-glycidyl vinyl ether copolymer rubber, propylene-tetrafluoroethylene copolymer rubber, vinylidene fluoride-hexafluoro Propene copolymer rubber, tetrafluoroethylene-perfluorovinylether copolymer rubber, vinylidene fluoride-trifluorochloroethylene copolymer rubber, vinylidene fluoride-pentafluoropropene copolymer rubber, tetrafluoroethylene-ditylene-isobutylene copolymer rubber .

Ethylene-hexafluoropropene copolymer rubber 1, tetrafluoroethylene-butene-1 copolymer rubber, tetrafluoroethylene-ethyl vinyl ether copolymer rubber, perfluoroalkyl acrylate elastomer, fluorine-containing nitroso-type elastomer, fluorine-containing siloxane type Elastomers and the like are used.

Among these various fluororubbers, propylene-tetrafluoroethylene-glycidyl vinyl ether copolymer rubber, in which glycidyl groups are copolymerized, has excellent adhesion to the base material,
It is particularly suitable from the viewpoint of adhesiveness and workability during film formation. As a copolymer rubber that bends, propylene is about 4
0-50 mol%, about 40-50 tetrafluoroethylene
Mole count, glycidyl vinyl ether approximately 0.2-5 mol%
A copolymer having a copolymer composition of

The solid lubricant and fluororubber are both about 5-95% by weight.
, preferably in a proportion of about 20-80% by weight to form the mixture.

The mixture film is formed by dispersing the solid lubricant and fluororubber in an organic solvent, applying it to the surface of the molded product by any coating method such as dipping, spraying, or brushing, drying, and then applying the necessary coatings. Burning is done through processing. In this case, the organic solvent used is ethyl acetate, n-butyl acetate, amyl acetate, acetone, methyl ethyl ketone, etc., and a solution having a solid content concentration of about 5 to 50% by weight is formed therein.

When a copolymer rubber obtained by copolymerizing glycidyl vinyl ether is used as the fluororubber, a tertiary amine or a salt thereof is added as a vulcanizing agent for the fluororubber in an amount of about 0.1 per 100 parts by weight of the fluororubber. A coating solution is prepared by adding ~10 parts by weight. The vulcanizing agent can be added directly to the coating solution, but generally it is dissolved in a mixed solution containing an organic solvent such as ethyl acetate mentioned above and phenol, etc. that promotes the dissolution of the vulcanizing agent. It is used after

The surface of the molded product to be coated must be coated with a primer, e.g.
-Aminopropyltriethoxysilane.

N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane,
A silane coupling agent such as γ-glycidoxypropylmethyldimethoxysilane or at least one type of hexamethylsilazane is used as it is or in toluene,
It is preferable to apply the primer in a diluted form with an organic solvent such as n-hexane or methanol, and it is also possible to dissolve the primer in the coating solution and use it in combination.

The mixture film formed on the surface of the rubber molded product has a thickness of about 5 to 10
00μ, preferably about 5-100μ.

〔Effect of the invention〕

The present invention enables the surface of rubber molded products such as dynamic sealing materials to reduce adhesion while maintaining sealing properties by forming a mixture film of a solid lubricant and fluororubber on the surface of the molded product. It can be effectively applied to improve characteristics.

〔Example〕

Next, the present invention will be explained with reference to examples.

Example 1 Powdered polytetrafluoroethylene (Daikin product Lublon L5-F) 100 parts (weight, same hereinafter), propylene-tetrafluoroethylene-glycidyl vinyl ether (mole ratio 43155/2) copolymer rubber (Asahi Glass product, molecular weight approx. 60,000) and 1 part of γ-glycidoxypropyltrimethoxysilane was mixed with 300 parts of ethyl acetate to prepare a coating base solution.

Separately, prepare a vulcanizing agent solution consisting of 15 parts of ethyl acetate, 4 parts of phenol, and 1 part of tris(dimethylaminomethyl)phenol, and add 1 part of this and 1 part of the above base resin solution.
A coating solution was prepared from 00 parts.

A primer solution prepared by dissolving 1 part of γ-glycidoxypropyltrimethoxysilane in 100 parts of toluene is applied to the surface of a fluororubber molded product, and after drying this at 25°C for 30 minutes, the above coating solution is applied. did.

After drying in an oven at 50°C for 2 hours, baking was performed in an oven at 200°C for 30 minutes to form a 15μ thick mixture film on the surface of the molded product.

The following items were measured for this mixture film-formed fluororubber molded product.

Friction coefficient: A load of 50 g was measured using a point pressure dynamic friction coefficient measurement method using a HEIDON-14 surface property measuring machine manufactured by Shinto Kagaku.
Measured at a speed of 50 cm/min Adhesion: The end face of a round rod sample with a diameter of 11 was brought into contact with a surface-polished aluminum plate, and the contact surface was placed in an oven at 200°C with a pressure of 50 g applied. , when taken out after 24 hours, measure the force required to peel off the sample and the aluminum plate.Sealing property: In the state of contact between the round rod-shaped sample and the aluminum plate, the contact area is approximately 0.8-
When a small hole with a perforation area of about 0.1 - is provided on the aluminum plate side at the center of the circular contact part, and compressed air is sent toward the hole at a pressure of 0.35 kg/aJ. Measurement of the amount of air leakage at the contact surface using a flowmeter Example 2 In Example 1, the amount of propylene-tetrafluoroethylene-glycidyl vinyl ether copolymer rubber used was
Changed to 00 copies.

Comparative Example 1 Similar measurements were performed on the fluororubber samples used to form the molded products of Examples 1 and 2.

Comparative Example 2 A coating of a 1:1 weight ratio of powdered polytetrafluoroethylene (Lubrune L5-F) and polyamide-imide resin was formed on the surface of the molded products of Examples 1 and 2 to a thickness of 15 μm. The same measurements were carried out.

The results obtained in each of the above Examples and Comparative Examples are shown in the following table.

Table 1 1 Dingya 1-J Junyokkei” Friction coefficient after completion of the drama
0.15 0,40 1,30 0.15
Adhesion (kgf) 0.5 3.0 12.0 0.
5 Sealing performance (+sl/min) <0.1 <0.
1 <0.1 5.0 Procedural amendment (0.

Claims (1)

[Scope of Claims] 1. A rubber molded article whose surface is coated with a mixture film of a solid lubricant and fluororubber. 2. The rubber molded article according to claim 1, wherein the solid lubricant is polytetrafluoroethylene. 3. The rubber molded article according to claim 1, wherein the fluororubber is a propylene-tetrafluoroethylene-glycidyl vinyl ether copolymer rubber. 4. The rubber molded article according to claim 1, wherein the mixture coating is formed to have a thickness of about 5 to 1000 microns.