JPS63280967A - Manufacture of fluorine resin covered rubber o-ring - Google Patents

Abstract

PURPOSE:To manufacture a seal material having both rubber-like elasticity and sufficient corrosion proof against corrosive fluid by inserting a string-like elastomer into the inside of fluorine resin tube to make a ring-like tube, heating, melting and interconnecting both ends of the tube. CONSTITUTION:A fluorine resin tube 1 of PFA or FEP material is cut to a predetermined length and a string-like elastomer 2 having the diameter conforming to the inside of said pipe is inserted in said tube 1. Said elastomer 2 is cut to the length corresponding to that of said tube 1. Next, they are set in a metal mold, heated and fusion interconnected on both ends of said tube 1 to form a seamless complete cover. Also, preferably the seam of said elastomer 2 does not coincide with that of said tube 1.

Description

[Detailed Description of the Invention] B) Industrial Application Field Is this invention contaminated by corrosive fluids and eluates from sealing materials?
: This relates to a method for producing rubber O-rings coated with fluororesin, which are used as sealing materials for containers, transportation equipment, piping, etc. that handle unwanted fluids.

(B) Prior Art Conventionally, O-rings made of fluororubber, silicone rubber, nitrile rubber, thermoplastic elastomer, fluororesin, etc. have been widely used as sealing materials for containers, transportation equipment, piping, etc. that handle corrosive fluids. However, these rubbers and elastomers did not have sufficient corrosion resistance, and deterioration such as swelling and hardening was observed over time. Further, purity f: A single O-ring made of fluororesin was used for the fluid required.

However, although fluororesin alone has sufficient corrosion resistance and purity, it lacks rubber-like elasticity and has drawbacks in sealing performance. For this reason, attempts have been made to combine fluororesin and rubber elastic material. For example, a method has been adopted in which a fluororesin sheet is preformed into a ring shape, a rubber elastic body is placed in the center of the ring, the material is sandwiched between molds, and the fluororesin sheet is melted and bonded by heating and pressure. (C) Purpose of the Invention This invention involves inserting a string-like rubber elastic body inside a fluororesin chip, and forming a ring shape by fully melting and joining both ends of the rubber elastic body. The aim is to stabilize the quality and provide the product at a low cost through mass production.

B) Means for Solving All Problems The manufacturing method for obtaining the fluororesin-coated rubber O-ring of the present invention will be explained as follows based on the drawings.

FIG. 1 shows the entirety of a fluororesin temporary rubber O-ring in which a string-like rubber elastic body (2) is completely covered with a fluororesin tube (2).

Fig. 2 shows the state before the fluororesin tube (1) is fully inserted into a string-like rubber elastic body (2) in the form of a ring and both ends thereof are melt-bonded, and Fig. 3 shows the mold 2 for melt-bonding.

First, cut the fluorine #i fat cheap ■ to a predetermined length, and insert the string-like rubber elastic body ■ with a diameter that matches the inside of it.

Cut the length of the string-like rubber elastic body ■ to match the length of the flowing plastic resin.

Next, by setting this in the mold shown in FIG. 3 and heating it, both ends of the fluororesin tube (2) are melted and joined, forming a complete, seamless covering. It is preferable that the seam of the string-like elastic body (■) be joined and not at the position of the seam of the fluororesin tube (■).

In addition, if the target O-ring has a large diameter, this invention allows you to manufacture O-rings of any size by melting and joining only a part of the circumference using a mold. PFA (tetrafluoroethylene, par 70-alkyl vinyl ether copolymer resin 11&) and PEP (tetrafluoroethylene/hexafluoroethylene brohylene copolymer resin) are suitable for the fluorine at fat cheap material used for.

This fluororesin tube ■ has residual stress due to the molecular orientation during extrusion molding, so it tends to expand and contract when heated during melt bonding.To avoid this, heat it in advance to remove as much of the stress as possible. It is necessary. For example, it is desirable to preheat PFA to 250 C'FEP to 180 CcLc.

The material of the string-like rubber elastic body (■) needs to be able to withstand the melting temperature of the fluorine resin tube (■) for several minutes, so fluorine rubber, silicone rubber, etc., which have high heat resistance, are optimal.

(E) Effects of the Invention As explained above, this invention involves inserting a string-like rubber elastic body inside a fluororesin tube, setting it in a ring shape in a mold, and heating it to completely melt and join the both ends. Using a simple method, mass production of fluororesin-coated rubber O-rings that maintains full rubber-like elasticity, has sufficient corrosion resistance against corrosive fluids, and can be used stably and for long periods of time as sealing materials for containers, transportation equipment piping, etc. This makes it possible to make it easier to use and provide it at a lower cost.

[Brief explanation of drawings]

Claims (1)

[Claims] 1. A method for producing a rubber O-ring coated with a fluororesin, which is characterized by inserting a string-like rubber elastic body inside a fluororesin tube, forming a ring shape, and melting and joining both ends of the string.