JPH11255930A - Non-tacky fluororubber and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a non-tacky fluororubber excellent in nontackiness of the rubber surface while having elastic characteristics required for the rubber itself and useful as a valve, a packing, a sealing material, etc., by composing the rubber so as to provide the surface of a vulcanized fluororubber with a specific non-tacky layer. SOLUTION: This rubber is composed so as to provide the surface of (A) a vulcanized fluororubber with (B) a non-tacky layer having the surface treated with a surface treating agent consisting essentially of a phosphorus-based cross- linking agent such as preferably a bisphenolphosphonium salt represented by the formula (R and R' are each H or the like). The component A is obtained by adding and mixing magnesium oxide, carbon black and Ca(OH)2 with, e.g. a vinylidene fluoride-hexafluoropropylene copolymer and vulcanizing the fluororubber. The resultant rubber is produced by applying the surface treating liquid to the component A according to a dipping method, etc., and then heat- treating the prepared component A preferably at a temp. of 20-120 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-adhesive fluororubber and a method for producing the same, and more particularly, to a non-adhesive fluororubber in which the crosslink density of only the surface of the fluororubber is increased to reduce the adhesiveness and a method for producing the same. .

[0002]

2. Description of the Related Art In addition to excellent rubber elasticity, fluororubber vulcanizates have excellent heat resistance, oil resistance and ozone resistance, and are widely used as valves, packings and sealing materials. These materials are often used to maintain sealing properties, and are usually used in a state of contact with metal or plastic.

[0003] However, since the surface of the vulcanized fluororubber has tackiness, if the state of contact with metal or plastic is prolonged, the vulcanized fluororubber and metal or the like will adhere to each other. For example, when used as a valve of an opening / closing valve, there is a problem that the original opening / closing function as the opening / closing valve does not work properly, and when used as a packing, it is difficult to perform a regular replacement work. Was.

[0004] In order to solve such a problem, various proposals have conventionally been made for reducing the tackiness of the rubber surface while maintaining the elastic properties of the rubber itself. These proposals can be roughly divided into (1) a treatment by compounding a rubber composition, for example, a method of lowering the tackiness of the rubber itself by compounding a filler, and (2) a modification treatment of only the rubber surface, for example, And a method of increasing the crosslinking density only on the rubber surface and decreasing the adhesiveness.

[0005]

However, non-adhesive fluororubbers which have been proposed and have been treated in a known manner can be expected to reduce the adhesiveness of the rubber surface to some extent. In some cases, better non-adhesiveness of the rubber surface may be required than before, and in such a case, conventionally known ones cannot cope.

The present invention has been made in view of such circumstances, and the object of the present invention is to provide not only the rubber itself with the elastic properties required, but also a more excellent An object of the present invention is to provide a non-adhesive fluororubber having a non-adhesive property on a rubber surface and a method for producing the same.

[0007]

Means for Solving the Problems In order to solve the above problems, the inventors of the present application have conducted intensive studies, particularly focusing on a crosslinking agent used for increasing the crosslinking density on the rubber surface. The present inventors have found that the use of a phosphorus-based compound as a cross-linking agent makes it possible to reduce the tackiness of the rubber surface more than before, and has arrived at the present invention.

That is, the non-adhesive fluororubber of the present invention has a non-adhesive layer which is surface-treated with a surface treatment liquid containing a phosphorus-based crosslinking agent as a main component on the surface of a vulcanized fluororubber. It is configured as follows.

The method for producing a non-adhesive fluororubber of the present invention is characterized in that a surface treatment liquid containing a phosphorus-based crosslinking agent as a main component is adhered to the surface of a vulcanized fluororubber, followed by heat treatment. It is composed of

In a more preferred embodiment of the present invention, the phosphorus-based crosslinking agent is a bisphenolphosphonium salt represented by the following general formula (1) (wherein R and R ′ each represent hydrogen Or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms).

[0011]

Embedded image The heat treatment temperature in the method for producing a non-adhesive fluororubber of the present invention is configured to be 20 ° C to 120 ° C.

[0012]

Embodiments of the present invention will be described below in detail.

[0013] The non-adhesive fluororubber of the present invention is obtained by using a surface treatment liquid containing a main part of a vulcanized fluororubber obtained by vulcanizing the fluororubber and a phosphorus-based crosslinking agent as a main component. It has a non-adhesive layer whose surface is surface-treated. That is, the non-adhesive fluororubber of the present invention has only a very non-adhesive non-adhesive layer formed on its surface only,
The main part of the rubber except the non-adhesive layer has elastic properties inherent to rubber.

The non-adhesive layer in the present invention is formed by treating the surface of a vulcanized fluororubber with a surface treatment solution containing a phosphorus-based crosslinking agent as a main component as described above.

The phosphorus-based crosslinking agent used in the present invention is preferably a bisphenolphosphonium salt represented by the following general formula (1).

[0016]

Embedded image In the general formula (1), R and R ′ each represent hydrogen or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms (particularly preferably, an alkyl group having 1 to 4 carbon atoms). Among these, further preferred forms of R and R ′ are
These are a methyl group and an ethyl group. R and R ′ may be the same substituent or different substituents.
These may be used alone or in combination of two or more.

By using such a crosslinking agent,
The adhesiveness of the rubber surface can be reduced more than before. Of course, the balance with the elasticity of the rubber main part for maintaining the sealing property is also very good.

Such a phosphorus-based cross-linking agent usually becomes a surface treatment liquid for the rubber surface by being mixed in a solvent. The content of the phosphorus-based crosslinking agent is 5 to 15 parts by weight, preferably 8 to 12 parts by weight, based on 100 parts by weight of the solvent. If this content is too large, the reaction will be excessive and the surface will be hardened excessively, resulting in a problem that the sealing property will be reduced.If the content is too small, the reaction will be insufficient and satisfactory non-adhesiveness will result. The disadvantage that it cannot be obtained occurs.

As the solvent, for example, an alcohol solvent such as methyl alcohol is preferably used.

The material of the fluororubber vulcanizate used in the present invention is not particularly limited, and various rubber materials such as binary and ternary rubbers are used. Specific preferred examples include vinylidene fluoride-propylene hexafluoride copolymer,
Examples include terpolymers of vinylidene fluoride-propylene hexafluoride-ethylene tetrafluoride, terpolymers of vinylidene fluoride-ethylene tetrafluoride-perfluorovinyl methyl ether, and the like.

The above-mentioned vulcanized fluororubber is produced by various known general methods. That is, vulcanizing agents,
A vulcanized fluororubber can be obtained by adding an organic or metal accelerator, a stabilizer, a plasticizer, and the like and vulcanizing under general vulcanizing conditions. Further, fillers such as carbon black and silica may be contained as additives.

Next, a method for producing the non-adhesive fluororubber of the present invention will be described.

First, a surface treatment liquid containing the above-mentioned predetermined phosphorus-based crosslinking agent is prepared, and this surface treatment liquid is adhered to the surface of the fluororubber vulcanizate to be treated. When adhering, the surface of the fluororubber vulcanizate is immersed in a solution of the surface treatment liquid (immersion method), or the surface treatment liquid is sprayed on the surface of the fluororubber vulcanizate (spraying method). Or a method (coating method) of applying a surface treatment liquid to the surface (partially or entirely). Which of these adhesion methods is selected may be appropriately selected in consideration of the degree of non-adhesion, cost, and the like.

The fluororubber vulcanizate thus treated with the surface treatment liquid is preferably subjected to a heat treatment. Suitable heat treatment conditions are a temperature of about 20 ° C to 120 ° C,
The processing time is about 60 to 90 minutes. When the adhesion treatment is performed by the immersion method, usually, washing is performed with water or alcohol in order to remove unreacted substances.
The heat treatment is performed again for about 5 to 24 hours to complete the process. Also, when the adhesion process is performed by the coating method,
Usually, after the first heat treatment is performed, washing is performed with water or alcohol, and then drying is performed to complete the treatment.

[0025]

The present invention will be described below in further detail with reference to specific examples.

Example 1 First, a fluororubber vulcanizate and a surface treatment liquid for a rubber vulcanizate were treated in the following manner.
Each was prepared and prepared.

Preparation of Fluorinated Rubber Vulcanizate Vinylidene fluoride-propylene hexafluoride binary copolymer (Daiel G-701, manufactured by Daikin Industries, Ltd.) 10
A masterbatch consisting of 0 parts by weight, 15 parts by weight of magnesium oxide (Kyowa Mag # 30, manufactured by Kyowa Chemical Industry Co., Ltd.), and 10 parts by weight of carbon black (Thermax MT, manufactured by Cancarb Co.) was mixed with 6 parts by weight of Ca ( OH) ₂ was added and mixed, and the mixture was thermally vulcanized at 170 ° C. for 10 minutes to obtain a fluororubber vulcanizate.

Preparation of Surface Treatment Solution A surface treatment solution containing 10 parts by weight of a bisphenolphosphonium salt represented by the above formula (1) and 10 parts by weight of a vulcanizing agent in 100 parts by weight of methyl alcohol was prepared.

Sample preparation based on specific surface treatment operations
The surface treatment solution of manufacturing the above were above the fluororubber vulcanizate are immersed for 60 minutes at 20 ° C. (heat treatment), then the surface of the fluororubber vulcanizate are washed with aqueous methanol, dried, and thereafter, 200 ° C. A re-heat treatment was performed for 4 hours to produce a sample of Example 1.

The thus prepared sample of Example 1 was subjected to an adhesion test on the rubber surface in the following manner.
The adhesive strength (adhesive strength) was determined.

(Tackiness test of rubber surface) The surface-treated vulcanized fluororubber was processed into a donut shape having a contact area of about 1 cm ² , contacted with a PBT (polybutylene terephthalate) plate, and a 1 kg load was applied. , Temperature 60 ° C, humidity 80
% Atmosphere for 72 hours. Thereafter, the adhesion strength was measured using a strograph (W2-C type, manufactured by Toyo Seiki Seisaku-sho, Ltd.), and a measurement test of the adhesive strength was performed.

The average value of the adhesive force (adhesive force) obtained by using the above method is 70 g / cm ² (maximum value: 285 g / cm ² ).
cm ² ; minimum value: 0 g / cm ² ). In addition, each sample has moderate rubber elasticity, and the balance between surface hardening (non-adhesiveness) for preventing surface adhesion and elasticity for maintaining sealing properties is very good. Was confirmed.

(Comparative Example 1) For comparison with the above-mentioned Example 1, a sample of Comparative Example 1 in which no rubber surface treatment was performed was produced. The sample of Comparative Example 1 was subjected to the same adhesion test as described above, and the average value of the obtained adhesion (adhesion) was 2000 g / cm ² (maximum value:
4285 g / cm ² ; minimum value: 1142 g / cm ² ).

[0034]

The effects of the present invention are apparent from the above results. That is, the non-adhesive fluororubber of the present invention is configured to have a non-adhesive layer surface-treated with a surface treatment liquid containing a phosphorus-based crosslinking agent as a main component on the surface of the fluororubber vulcanizate. Therefore, the rubber surface is much more non-adhesive than the conventional one. Of course, the rubber has moderate rubber elasticity, and the balance between surface hardening for preventing surface adhesion and elasticity for maintaining sealing properties is very good. As a result, the range of selection of the non-adhesive rubber can be broadened according to the application, as compared with the related art.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsuhiko Sekine 1-840 Mitsuhashi, Omiya City, Saitama Prefecture Inside the Omiya Plant of Fujikura Rubber Industries, Ltd.

Claims (5)

[Claims] 1. A non-adhesive fluororubber comprising, on a surface of a vulcanized fluororubber, a nonadhesive layer surface-treated with a surface treatment solution containing a phosphorus-based crosslinking agent as a main component. 2. The phosphorus-based crosslinking agent is a bisphenolphosphonium salt represented by the following general formula (1) (wherein R and R ′ are each hydrogen or substituted or unsubstituted The non-adhesive fluororubber according to claim 1, which represents an alkyl group having 1 to 6 carbon atoms). Embedded image 3. A method for producing a non-adhesive fluororubber, which comprises applying a surface treatment liquid containing a phosphorus-based crosslinking agent as a main component to the surface of a vulcanized fluororubber, followed by heat treatment. 4. The phosphorus-based crosslinking agent is a bisphenolphosphonium salt represented by the following general formula (1) (wherein R and R ′ are each hydrogen or substituted or unsubstituted The alkylene group having 1 to 6 carbon atoms). Embedded image 5. The method according to claim 3, wherein the heat treatment temperature is 20 ° C. to 120 ° C.