JPH0633822B2 - Method for manufacturing diaphragm valve membrane - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for manufacturing a diaphragm valve membrane, and more specifically, polytetrafluoroethylene (hereinafter referred to as PTF).
(Hereinafter sometimes abbreviated as “E”) and the like.

Technical Background of the Invention and Problems Thereof In a diaphragm pump or diaphragm valve, fluid movement is controlled by displacing and driving a diaphragm valve membrane by air pressure. The diaphragm valve body used for such a diaphragm pump or diaphragm valve generally has a structure as shown in FIG. That is, the diaphragm valve body 1 is
A valve membrane main body 2 made of fluororesin such as PTFE whose central portion is curved in an arc shape excluding the circumferential portion, and a back rubber provided on the back surface of the valve membrane main body 2 in substantially the same shape as the main body 2 are called. And a reinforced rubber valve membrane 3 made of rubber, and a boss portion 4 for attaching the valve membrane body 2 to the diaphragm pump body or the diaphragm valve body is provided in the central portion of the valve membrane 2. And in this rubber reinforced valve membrane 3,
The reinforcing core material 3a may be embedded, and the valve membrane main body 2
Are reinforced.

By the way, since fluororesins such as PTFE have excellent chemical resistance and heat resistance, in industries such as the semiconductor manufacturing industry that are extremely reluctant to contaminate fluids controlled by diaphragm valve bodies or diaphragm pumps. Used favorably. And in recent years in the semiconductor manufacturing field,
The size of the apparatus is being increased for the purpose of improving the processing capacity, and accordingly, an apparatus that can be used under high temperature and under high pressure is required.

However, the PT having the rubber-reinforced valve membrane 3 as described above
Fluorine resin valve membranes such as FE have a serious problem that they cannot withstand use under high temperature and high pressure conditions. This is because the strength of fluororesins such as PTFE decreases sharply at high temperatures.

In order to solve such a problem, it is conceivable to thicken the rubber-reinforced valve membrane or the fluororesin valve membrane itself such as PTFE. However, if the thickness of the leaflet is increased, the flexibility or operability of the leaflet is impaired, and the durability of the leaflet is also reduced. Further, as described above, in the semiconductor manufacturing field, the contamination of the processing fluid is extremely disliked. Therefore, it is not always preferable to use the rubber reinforced valve membrane.

Therefore, it is strongly desired to develop a method for manufacturing a diaphragm valve membrane that can obtain a diaphragm valve body having excellent flexibility and operability that can be used under high temperature and high pressure conditions without using a rubber reinforced valve membrane. It was rare.

An object of the present invention is to solve the problems associated with the prior art as described above, and does not use a rubber reinforced valve membrane that may contaminate a processing fluid, and yet high temperature and high pressure. It is an object of the present invention to provide a method for producing a diaphragm valve membrane that exhibits excellent flexibility and operability even when used under conditions.

SUMMARY OF THE INVENTION The method for manufacturing a diaphragm valve membrane according to the present invention includes a fluororesin valve membrane forming sheet, a reinforcing cloth having heat resistance,
The sheet and the reinforcing cloth are integrated by inserting through a fluororesin powder or a heat-meltable fluororesin film or both, and then compressing while heating to a temperature not lower than the melting point of the fluororesin forming the valve membrane. It is characterized by that.

DETAILED DESCRIPTION OF THE INVENTION A method for manufacturing a diaphragm valve membrane according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a diaphragm valve body including a diaphragm valve membrane obtained by the present invention, and FIG.
It is a schematic cross section explaining the diaphragm valve membrane obtained by this invention. In the following description, the same members as those of the diaphragm valve body shown in FIG. 3 are designated by the same reference numerals.

A diaphragm valve body 1 including a diaphragm valve membrane 8 obtained according to the present invention includes a diaphragm valve membrane 8 whose central portion is curved in an arc shape except for a circumferential portion, and the diaphragm valve membrane 8 which is a diaphragm pump main body or a diaphragm valve main body. The diaphragm valve membrane 8 is composed of a valve membrane main body 2 made of a fluororesin and a reinforcing member 5 embedded in the valve membrane main body 2.

Next, a method for manufacturing the above diaphragm valve membrane will be specifically described.

In the method for manufacturing a diaphragm valve membrane according to the present invention, first,
A sheet for forming the valve leaflet main body 2 is made of fluororesin.

The fluororesin used is polytetrafluoroethylene (PTFE), PF which is a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether.
Examples thereof include A, FEP which is a copolymer of tetrafluoroethylene and hexafluoropropylene, and EPE which is a copolymer of tetrafluoroethylene, hexafluoropropylene and perfluoroalkyl vinyl ether. Of these, considering the mechanical strength of the valve leaflet main body 2,
PTFE is particularly preferred.

As described above, at the stage of forming the sheet for forming the valve membrane main body 2 from the fluororesin, it is not necessary to use the sheet for forming the valve membrane main body formed with a curl, and a flat film-like fluororesin is used. In addition, you may use the sheet | seat with which the center part of the film-shaped fluororesin was attached.

Techniques for forming a film-shaped valve body main body forming sheet from such a fluororesin are known, and any of these known methods can be adopted. For example, PTFE molding powder is preformed under a pressure of 100 to 300 kg / cm ² , and the obtained preform is fired at a temperature of 327 ° C. or higher to prepare a cylindrical shaped product, and then this cylindrical shaped product is prepared. A sheet for forming the valve membrane main body 2 is obtained by removing the film to form a film, heating the film PTFE to a temperature of 327 ° C. or higher to form a gel, and then rapidly cooling. Alternatively, in a mold having a space corresponding to the shape of the valve membrane main body forming sheet,
After filling with PTFE molding powder and pressurizing and preforming, the obtained film-like preform is prebaked to a temperature of 327 ° C. or higher, and then heated again to a temperature of 327 ° C. or higher to be in a gel state. Just quench it. Furthermore,
A mixture of unsintered PTFE fine powder and a liquid lubricant is biaxially rolled to form a film, and the liquid lubricant is removed from the obtained film body and baked at a temperature of 327 ° C. or higher. It may be rapidly cooled to obtain a valve body main body forming sheet.

Next, a reinforcing cloth 5 having heat resistance as described below is inserted between the above-mentioned sheets for forming a valve-membrane main body made of a fluororesin through the fluororesin powder or the heat-meltable fluororesin film or both of them.

The reinforcing cloth 5 embedded in such a valve membrane body preferably has heat resistance, and specifically, cloth made of aromatic polyamide fiber or the like is preferably used. As the cloth, any of woven cloth such as woven cloth, knit, braid, lace, net, and non-woven cloth can be used. Felt is also used as the non-woven fabric.

Specifically, the reinforcing cloth 5 as described above is sufficiently impregnated with PTFE dispersion, PFE dispersion, FEP dispersion or EPE dispersion, and the fluororesin powder 6 is attached to the reinforcing cloth 5. This dispersion is preferably made of the same fluororesin material as the fluororesin forming the valve membrane main body. For example, when using a PTFE valve membrane, it is preferable to use PTFE dispersion.

Next, the reinforcing cloth 5 treated as described above is heated to a temperature equal to or lower than the melting point of the fluororesin powder 6 contained in the dispersion to evaporate the solvent and the like, and thereafter, two fluororesin valve membrane moldings are formed. It can be sandwiched between sheets for use.

The PTFE dispersion was 25c.
p. It is commercially available as an aqueous suspension having a resin content of 60% by weight, and can be applied or impregnated to a reinforcing cloth as it is. In this way, the reinforcing cloth 5
The purpose of adhering the fluororesin powder 6 is to improve the adhesiveness between the fluororesin valve membrane forming sheet and the reinforcing cloth 5.

In the present invention, as described above, the reinforcing cloth to which the fluororesin powder is adhered may be sandwiched between the fluororesin valve film forming sheets, and a heat such as PFA or FEP may be provided between the fluororesin valve film forming sheets. The reinforcing cloth 5 may be inserted via the fusible film 7.

Of course, as shown in FIG. 2, the reinforcing cloth 5 to which the above-mentioned fluororesin powder 6 is adhered is inserted through the fluororesin film 7 such as PFA or FEP, which is heat fusible, to form a fluororesin valve film forming sheet. It may be inserted between 2a, and in this case, a strong adhesion is obtained between the valve body 2 and the reinforcing cloth 5.

Since the reinforcing cloth 5 has many meshes or irregularities on its surface, it is considered that the reinforcing cloth 5 is firmly bonded to the fluororesin valve membrane main body 2 via the fluororesin powder 6 or the fluororesin film 7. .

Next, after inserting the reinforcing cloth 5 between the fluororesin valve membrane forming sheets 2a as described above, the obtained reinforcing cloth insert is used to form the fluororesin valve membrane forming sheet 2a. While being heated (compressed) to a temperature equal to or higher than the melting point, the fluororesin valve membrane forming sheet 2a and the reinforcing cloth 5 are bonded to each other to integrate them. For example, PT
When using the FE valve film forming sheet 2a, 327
~ 380 ° C, preferably 2-3kg / c at a temperature of 340 ° C
A pressure of m ² is sufficient. When aromatic polyamide fibers (Kevlar) are used as the reinforcing cloth 5, the Kevlar decomposition temperature is around 425 ° C., so that no significant deterioration of the Kevlar is observed even when pressure is applied under such temperature conditions. .

After the fluororesin valve membrane main body 2 and the reinforcing cloth 5 are integrated in this manner, the obtained valve cloth with a reinforcing cloth (diaphragm valve membrane) 8 is heated to a temperature equal to or lower than the melting point of the fluororesin forming the diaphragm valve membrane. (In other words, it is heated to a temperature equal to or lower than the melting point of the fluororesin forming the valve membrane main body 2) and the central portion of the diaphragm valve membrane 8 is bent in an arc shape.
This method is known in the art.

In the diaphragm valve membrane 8 thus obtained, the heat-resistant reinforcing cloth 5 is embedded over almost the entire length.

By thus embedding the reinforcing cloth 5 in the fluororesin valve body 2 as described above, the strength of the valve membrane is dramatically improved and a valve body having flexibility is obtained. Even without using, a diaphragm valve membrane that can be sufficiently used alone can be obtained. In particular, even under high temperature and high pressure conditions, its operability is not lost, and a diaphragm valve membrane excellent in durability and bending fatigue characteristics can be obtained. In addition, since the reinforcing cloth 5 is embedded in the fluororesin, it does not come into direct contact with the fluid, so that there is no possibility of contaminating the fluid at all.

The method of using the diaphragm valve membrane obtained by the present invention is
It is similar to a conventional diaphragm valve membrane.

Further, a method for attaching the boss portion 4 to the diaphragm valve membrane 8 is known, and for example, the diaphragm valve membrane 8 and the boss portion 4 can be mechanically attached, or can be attached via a heat-melting fluororesin. You can also

The diaphragm valve body 1 thus obtained has a diaphragm valve membrane 8 whose central portion is curved in an arc shape excluding the circumferential portion, and a boss portion for attaching the diaphragm valve membrane 8 to the diaphragm pump main body or the diaphragm valve main body. And the diaphragm valve membrane 8 described above.
Is composed of a valve membrane main body 2 made of fluororesin and a reinforcing cloth 5 embedded in the valve membrane main body 2.

The diaphragm valve membrane obtained by the present invention can be used by attaching the boss portion as described above, but it can also be applied to a flat plate diaphragm, a dish diaphragm, a folded diaphragm, etc., which is made of only the diaphragm valve membrane without attaching the boss portion. Applicable.

Advantageous Effects of Invention In the method for manufacturing a diaphragm valve membrane according to the present invention, PTF is used.
Fluororesin for forming a valve membrane by inserting a heat-resistant reinforcing cloth such as aromatic polyamide between fluororesin valve membrane-forming sheets such as E through a fluororesin powder and / or a heat-meltable fluororesin film, and then forming a valve membrane (That is, since the valve membrane main body and the reinforcing cloth are integrated while being compressed while being heated to a temperature equal to or higher than the melting point of the fluororesin forming the valve membrane main body, the fluororesin valve membrane main body and the reinforcing cloth strongly adhere to each other,
Even if they are used under high temperature and high pressure, they do not separate, and a diaphragm valve membrane exhibiting excellent flexibility and operability under high temperature and high pressure can be obtained.

[Brief description of drawings]

1 is a sectional view of a diaphragm valve body including a diaphragm valve membrane obtained by the present invention, and FIG. 2 is a sectional view of a diaphragm valve membrane obtained by the present invention,
FIG. 3 is a sectional view of a conventional diaphragm valve body. 1 ... Diaphragm valve body, 2 ... Valve body, 2a ... Diaphragm valve film forming sheet, 3 ... Reinforcing valve film, 4 ... Boss part, 5 ... Reinforcing cloth, 6 ...
Fluororesin powder, 7 ... Fluororesin film, 8 ... Diaphragm valve membrane.

Claims (5)

[Claims] 1. A fluorine-containing valve cloth is formed by inserting a heat-resistant reinforcing cloth between the fluororesin valve-membrane forming sheets via a fluororesin powder or a heat-meltable fluororesin film or both of them. A method for producing a diaphragm valve membrane, characterized in that the sheet and the reinforcing cloth are integrated by being compressed while being heated to a temperature equal to or higher than the melting point of the resin. 2. The method for producing a diaphragm valve membrane according to claim 1, wherein the fluororesin forming the valve membrane is polytetrafluoroethylene. 3. The method for producing a diaphragm valve membrane according to claim 1, wherein the reinforcing cloth is a woven cloth made of aromatic polyamide fiber. 4. The reinforcing cloth is impregnated with a fluororesin dispersion containing fluororesin powder, and is inserted between the fluororesin valve membrane forming sheets. Manufacturing method of diaphragm valve membrane. 5. A reinforcing cloth is impregnated with a fluororesin dispersion containing fluororesin powder, and then this reinforcing cloth is inserted between the fluororesin valve membrane forming sheets via a heat-meltable fluororesin film. The method for manufacturing a diaphragm valve membrane according to claim 1, wherein: