JPH049666B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Industrial Application This invention relates to a fluororesin composite material having a fluororesin layer heated and fired on the surface of a rubber material, and a method for producing the same.

(2) Conventional technology Fluororesins, such as tetrafluoroethylene resin (hereinafter referred to as
PTFE) tetrafluoroethylene-perfluorovinyl ether copolymer (hereinafter referred to as PFA),
As is well known, tetrafluoroethylene-hexafluoropropylene copolymer (hereinafter referred to as FEP) has excellent chemical resistance,
It has excellent properties such as heat resistance, electrical insulation, self-lubricating properties, and non-stick properties, and has a wide range of applications in industrial and daily life fields.However, these properties make it difficult to process. It is. Especially PTFE is 327
PFA has a transition point at 306°C, and PFA has a melting point at 306°C, and both can exhibit the above-mentioned excellent characteristics only when heated above this temperature.

For this reason, conventionally, PTFE,
Attempts have been made to form a PFA layer to overcome the drawbacks of the rubber material itself, such as non-adhesiveness, chemical resistance, solvent resistance, and oil resistance, but when PTFE and PFA are heated and baked,
Even if you use highly heat-resistant rubber, such as silicone rubber or fluorine rubber, the rubber material itself will decompose and deteriorate.
In reality, there has never been a rubber material with a heat-sintered layer of PTFE or PFA formed on its surface.

For this reason, conventionally, after producing fired sheets, tubes, sleeves, etc. of PTFE, PFA, etc.,
Paste rubber material or insert PTFE into the tube.
Inject PFA, or pour PFA,
A fired shrink tube of PTFE was created, and this shrink tube was placed over the surface of a rubber sheet, roll, rod, etc. and heat-shrinked. With these methods, there is a limit to how thin the layer of PTFE, PFA, etc. can be to lower the price, and also due to the characteristics of PTFE, PFA, etc.
Because the PFA layer is thick, it has the disadvantage that the elasticity, which is a characteristic of rubber materials, is significantly impaired. moreover
PTFE, PFA, etc. are extremely difficult to adhere to the surface of rubber materials due to their non-adhesive properties, so the surface of PTFE is etched with an alkali metal and the adhesive is bonded with a physical anchor effect. ,
I had to use a very complicated method of pasting it on top of that. In addition, in order to improve its adhesion, a method has been devised in which PTFE itself is made into a porous material and the porous material is bonded to rubber.

(3) Problems to be Solved by the Invention The present invention provides non-adhesive properties to the surface of the rubber material without damaging the elasticity of the rubber material, which could not be obtained by the conventional methods described above. The aim is to form an extremely thin heat-sintered layer of fluororesin that has excellent mold releasability, corrosion resistance, and solvent resistance.

(4) Means for solving the problems The composite material of the present invention has a heated and fired layer of fluororesin on the surface of the rubber material.

In addition, in the method for manufacturing the above composite material, the surface of the rubber material is coated with fluororesin, and then the fluororesin is heated to 500°C.
It is heated and baked at the above temperature in a very short time.

(5) Function The present invention includes unfired PTFE in the rubber material,
After coating PFA, FEP, etc. using methods such as laminating, dipping, and painting, this
It can be obtained by heating for a very short time at a temperature of 500°C or higher, which is higher than the transition point or melting point of PTFE, PFA, and FEP and is beyond conventional wisdom.

That is, conventionally, PTFE was usually fired at a temperature of 360° C. to 380° C. for 8 minutes or more (Plastic Materials Course 6 Futsuso Resin Nikkan Kogyo Shimbun Publishing, P86).

Therefore, the professional guidance for fluororesin also states that ``When compounding with fluororesin, the material to be coated must be iron, stainless steel, aluminum, glass, etc., as long as it can withstand the baking temperature (400℃). (Published by Daikin, POLYFLON)
Handbook P73), and with conventional existing technology, PTFE, PFA, and FEP can be baked at 360°C to 380°C.
It was said that it was necessary to take a long time to fire at a temperature of 400℃ or less.

The present invention surpasses existing technology and somehow manages to produce PTFE, PFA, and rubber materials without applying heat to rubber materials.
The idea of firing only the FED made it possible for the product to pass through temperatures of 500℃ or higher, which was unimaginable under conventional wisdom, in a short period of time.
Therefore, when analyzed structurally, the fluororesin is melted and fired by rapidly applying radiant heat as high as 500°C to the fluororesin surface, and the narrow temperature range in which fluororesin melts, which was previously thought, has been exceeded. This seems to overturn the logic that it cannot be fired unless it is heated for a certain period of time at a temperature within .

In the above manner, PTFE and PFA are added to the rubber material.
The above-mentioned rubber materials include not only silicone rubber and fluorine rubber, but also butyl rubber, ethylene vinyl acetate copolymer, and acrylic rubber depending on the temperature selection. Any material can be applied.
In addition, rubber materials can be processed into various complex shapes such as rolls, sheets, tubes, O-rings, and rods, and rubber materials can also be made into composite materials with other materials, i.e., It can be processed into various materials, such as fiber-containing materials, composite materials with metals, glass, and aromatic polyamides, and is not limited to the shape or structure of the rubber material. Additionally, rubber materials can be processed depending on the situation, such as applying fluorine treatment to the rubber material before vulcanization and then vulcanizing it, or applying fluorine treatment to the rubber material after vulcanization. Mechanically polished products, liquid honing treatment, chemical surface treatment, and of course,
Those without surface treatment can be used depending on the purpose and required characteristics.

Fluororesin coatings can also be applied to sheets, tubes, and rods by methods including aqueous dispersion, enamel dipping, painting, powder coating, and molding, extrusion, and rolling of a fluororesin compound containing a liquid lubricant. This includes all products that are manufactured and then crimped onto a rubber material as is, or are bonded together by crimping after removing the liquid lubricant, and are composited with a rubber material and then fired.

Therefore, the coating thickness of the fluororesin on the rubber material can be freely selected from about 10 .mu.m to about 1 mm.

(6) Examples Example 1 Rubber roller with silicone rubber pasted onto a metal shaft and finished with vulcanization, diameter φ80mm, roll length 600
After polishing the surface of mm with sandpaper #320,
Tetrafluoroethylene resin aqueous dispersion (Asahi Glass Co., Ltd. AD)
-1) to a thickness of about 18μ, dry it in a 200℃ oven for about 5 minutes, and then
A tunnel furnace with a diameter of 100 mm and a length of 2 m was manufactured at 650°C, and the rolls were rotated slowly in the furnace and passed through the furnace for about 4 minutes.

As a result, the tetrafluoroethylene resin, which was white and unbaked before passing through the furnace, became completely transparent and fired, and the surface of the silicone rubber roll was coated with silicone rubber covered with the tetrafluoroethylene resin. A composite roller with ethylene chloride resin was obtained. Thereafter, the hardness of this rubber was measured, and it was 50, which was exactly the same as the initial value, and there was no rubber deterioration.

Example 2 100 parts of PTFE fine powder (trade name: Polyflon F103, manufactured by Daikin Industries, Ltd.) and 23 parts of naphtha oil were mixed on one side of an unvulcanized fluororubber sheet with a thickness of 3 mm, a width of 150 mm, and a length of 200 mm. After that, the sheet was extruded and pressurized, rolled to a thickness of 120μ using calendar rolls, dried and stretched, then placed in a hot plate press heated to 310℃, and left under a pressure of approximately 3Kg/cm ² for 1 hour. The mixture was heated and vulcanized.

As a result, a rubber plate with a PTFE sheet composite on one side was obtained.

However, the attached PTFE sheet was still in an unfired state.

The rubber plate thus obtained was passed under a radiant heat plate (length 50 cm) at a temperature of 530° C. for about 4 minutes.

As a result, an elastic sheet was obtained in which a completely fired PTFE sheet was attached to one side of a fluororubber sheet.

Example 3 Powdered PFA (manufactured by Dupont) was applied to a 10 mmφ acrylic rubber string to a thickness of about 20 μ by powder coating, and after drying by heating at 120°C for about 15 minutes, the temperature was adjusted to 900°C. It was run at a speed of 20 m/min through a 1 m long furnace.

As a result, the PFA was translucent and milky white, and a composite material was obtained in which the fired PFA was wrapped around the rubber string.

When this material was subjected to a tensile test, the tensile strength was 156, which was almost no different from that of a single rubber cord.
Kg/cm ² and elongation of 140%, making it an elastic composite material.

(7) Effects According to the manufacturing method of the present invention, the elasticity of the rubber material, which could not be obtained with conventional methods, is not impaired, and the non-adhesion, mold releasability, corrosion resistance, and solvent resistance of PTFE and PFA are achieved. It is also possible to form an extremely thin film layer that has high properties, and can be manufactured at a lower cost.

In addition, the rubber and calcined PTFE obtained according to the present invention,
Composites with PFA and the like can be formed into sheets, rolls, tubes, strips, or any complex shape.

In addition, as a product processed into a composite material, it has chemical resistance,
It can be applied to O-ring rubber rolls, rubber sheets, rubber belts, coated cables, etc. that require corrosion resistance, mold release resistance, and elasticity.Furthermore, if fluororubber or silicone rubber is used as the rubber material, its heat resistance can be improved. It can be applied to the above products used in high temperature conditions in the range.

[Brief explanation of drawings]

The drawing is an enlarged cross-sectional view of the composite material of the present invention. 1...Rubber material, 2...Heat-sintered layer of fluororesin.

Claims (1)

[Claims] 1. After coating the surface of the rubber material with an unfired fluororesin, the unfired fluororesin is heated and fired at a high temperature of 500°C or more and less than 900°C to form a heated and fired layer of fluororesin on the surface of the rubber material. A method for producing a fluororesin composite material, characterized by forming a fluororesin composite material.