JPH0599343A - Sanitary piping gasket and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a sanitary piping gasket excellent in heat resistance and chemical resistance further with a high compression restoring rate, having a stable high seal characteristic for a long period in a production device for medicines or the like. CONSTITUTION:In a sanitary piping gasket 1 which is a disk annular body of concentrically hollowing the center part to provide a predetermined thickness, having protruded parts (3) above and below a disk part (2) concentrically circular annularly with the annular body, the sanitary piping gasket is formed integrally of porous polytetrafluoroethylene with density of the disk part (2) 1.0 to 1.9g/cm<3> and density of the protruded part (3) 0.3 to 1.4g/cm<3>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sanitary piping gasket used in a piping system of a production apparatus for medicines, foods and the like. More specifically, the present invention relates to a sanitary pipe gasket integrally formed of porous polytetrafluoroethylene.

[0002]

2. Description of the Related Art Gaskets for sanitary piping used in manufacturing equipment for pharmaceuticals, foods, etc. are designed to prevent impurities from eluting into the product from the material forming them.
Materials were carefully selected, and in the past, many were made of silicone plastic. In the manufacture of the above drugs,
Since it is necessary to strictly control the product, the frequency of cleaning the device is extremely high as compared with other manufacturing devices. In these apparatuses, particularly in pharmaceutical manufacturing apparatuses, in order to remove pyrogen, which is a so-called heat-generating substance for living bodies, alkali cleaning or cleaning with alkali and saturated steam is often performed. However, conventionally used silicon-based plastics have poor alkali resistance and may have various adverse effects after cleaning. For example, even if a small amount of alkaline component remains on the gasket surface, there is a defect that the gasket adheres to the flange metal surface when the apparatus is steam sterilized.

On the other hand, in order to solve the drawbacks of the above-mentioned silicone plastic gaskets and to be used in various devices, polytetrafluoroethylene resin packings, gaskets, O-rings and the like having excellent heat resistance and chemical resistance are used. Sealing parts are known. For example, JP-A-63-2
No. 42610 and Japanese Patent Laid-Open No. 62-21819. Further, for example, Japanese Utility Model Publication No. 2-45594 proposes a sealing material using a stretched porous body of polytetrafluoroethylene.

[0004]

However, as a sanitary piping gasket that handles pharmaceuticals and the like that are strict against elution of impurities and require cleaning under severe conditions,
In particular, a gasket examined in consideration of usage conditions has not been proposed yet. The inventors initially applied a conventional polytetrafluoroethylene resin, which is also excellent in alkali resistance, to the sanitary piping gasket in place of the conventional silicone resin sanitary piping gasket. However, since the gasket for sanitary piping made of ordinary polytetrafluoroethylene resin used for conventional sealing members has a higher hardness than the conventional silicone resin, the tightening pressure of the flange portion must be increased. Gas such as steam leaks, and once the flange that has been tightened is retightened, it is extremely difficult to prevent the gas from leaking from the second tightening without elastic recovery to the original state. I found out. Therefore, based on the above findings, the inventors have excellent chemical resistance, particularly excellent alkali resistance,
The present invention has been achieved as a result of intensive studies aimed at providing a gasket for sanitary piping which is excellent in elastic recovery.

[0005]

According to the present invention, there is provided a disc annular body having a predetermined thickness which is formed by hollowing out a center portion in a concentric shape, and the disc portion is concentric with the annular body and protrudes upward and downward from the disc portion. In a gasket for sanitary piping having a portion, the disc portion has a density of 1.0 to 1.9 g / cm ³ , and the convex portion has a density of 0.3 to 1.4 g / cm ^3. A sanitary pipe gasket integrally formed by the above is provided.

Further, in a molding die which is a disc annular body having a predetermined thickness which is concentrically cut through the central portion, and which is formed concentrically with the annular body so as to have convex portions above and below the disc portion. With a density of 0.3-1.4 g / cm ³ and a thickness of 1-10 m
There is provided a method for producing the above-mentioned gasket for sanitary piping, in which a porous polytetrafluoroethylene sheet having a size of m is arranged, heated at room temperature or heated, and locally pressed in the thickness direction of the sheet to be molded.

[0007]

The present invention is constructed as described above and uses a gasket for sanitary piping, which is made of porous polytetrafluoroethylene, and has a disc portion density of 1.0 to 1.9 g / c.
m ³ and the density of the protrusions are integrally formed to 0.3 to 1.4 g / cm ³ , so they can be applied to joint parts such as ferrules and flanges that connect sanitary piping systems, and can be aligned with good positional accuracy. Can be easily fixed. Also, although the disc portion is porous, since it is molded to the above specific density,
In combination with the water repellency and mold releasability inherent in polytetrafluoroethylene, it is possible to prevent the sealing fluid from penetrating into the gasket surface and prevent the gasket of the present invention from adhering to the contact surface such as a ferrule or a flange. There is no possibility of sticking to the surface of a contact metal such as a ferrule like a silicone resin gasket. Furthermore, since the gasket of the present invention is porous, it is rich in elasticity, excellent in elastic recovery even after repeated use a plurality of times, high in shape restoring force, and excellent in sealability of the sanitary piping system to be applied. ..

The present invention will be described in detail below. FIG. 1 is a plan and cross-sectional explanatory view of one embodiment of the gasket for sanitary piping of the present invention, and FIG. 2 is a cross-sectional explanatory view of another embodiment of the gasket for sanitary piping of the present invention. In FIGS. 1 and 2, the disc-shaped gaskets 1 and 1 ′ have concentric annular protrusions 3 and 3 ′ on the disc portions 2 and 2 ′, respectively. Such a shape is prescribed by the International Organization for Standardization (ISO) as a gasket for sanitary piping. In particular, it is specified as a sanitary pipe gasket that is strict with respect to the purity of the contents so that it can be fixed at an appropriate position so as not to cause a liquid pool or the like inside the pipe. Therefore, the convex portions 3 and 3 ′ are
Place it so that it matches the position of the recess on the flange to be used. Further, the diameter r of the central space portion concentric with the disk portion of the gasket 1 of the gasket 1 is set to be substantially the same diameter according to the inner diameter of the flange to be applied, so that the adhesion or accumulation of the chemical liquid in the apparatus does not occur. Is formed as. The gasket 1'of FIG. 2 is exactly the same as the gasket of FIG. 1 except that it has a hook 4 for temporarily fixing the gasket to the flange at the outer peripheral edge portion. The thickness of the disk portion of the sanitary piping gasket after molding is not specified by ISO, but is usually 0.1 to 8 mm, preferably 0.5 to 5 mm.

The porous polytetrafluoroethylene of the present invention uses polytetrafluoroethylene as a porous material. The polytetrafluoroethylene (hereinafter referred to as PTFE) can be made porous by a known method, for example, a PTFE sheet having a melting point or lower and a width and thickness of 300 ° C. or higher while substantially maintaining its width and thickness. , A sheet stretching method in which it is stretched in the length direction to produce crazes and heat treated to make it porous, a mixture obtained by adding a liquid lubricant such as solvent naphtha or petroleum to PTFE is extruded, and the same as above. An extrusion stretching method for stretching, a method for burning and removing the combustible substance added to PTFE to remove the combustible substance to make it porous,
There is a porous method such as a sintering method in which fibrous PTFE is sintered to be porous. Further, PTFE used for the above-mentioned porosification
Unlike the conventional manufacturing of gaskets for general equipment, in order to prevent impurities and the like from eluting into the reaction products of equipment where sanitary piping gaskets are used, it is possible to add porous materials without adding inorganic substances or blending copolymers. It is preferable to use for qualification.

The porous polytetrafluoroethylene constituting the gasket for sanitary piping of the present invention has a disc portion density of 1.0 to 1.9 g / cm ³ (porosity 12 to 50).
%), And the density of the protrusions is 0.3 to 1.4 g / cm.
³ (porosity 40 to 86%). The density of the disk part is 1.
If it is less than 0 g / cm ³ , the permeation-preventing action is lowered, and
If it exceeds 1.9 g / cm ³ , the elasticity is poor and the conformability at the time of tightening becomes poor, which is not preferable. On the other hand, the density of less than 0.3 g / cm ³ of the convex portion is difficult arrangement fixed to the shape retention is difficult joint of protrusions, especially after the mounting workability, 0.6 g / cm ³ or more is preferable .. Also,
When the density of the convex portion exceeds 1.4 g / cm ³ , it becomes rigid,
It is not preferable because the fitting property of the joint portion such as the flange and the ferrule is lost. Further, in this case, in the gasket having the shape shown in FIG. 2, the density of the hook 4 is not particularly limited, and may be the same as that of either the convex portion 3 ′ or the disc portion 2 ′. It may be appropriately selected depending on the method.

In the present invention, the manufacture of the above sanitary piping gasket is not particularly limited. Preferably, porous PTFE having a small density corresponding to the convex portion of the gasket is used, and by heating and locally applying pressure in a mold for molding into the above-mentioned shape, a porous material having a density higher than that of the convex portion is formed. It is preferable to form a disc portion made of a flexible PTFE.

In the sanitary piping system of the present invention, the convex portion of the sanitary piping gasket is fitted into the concave portion of the joint portion such as the flange as described above, and then it is tightened with the ferrule flange or the like to secure the inside of the piping system. The flowed material is sealed and tightly joined without leaking to the outside. In the pipe system of the present invention joined as described above, it is usually 4 to 60 ° C. and / or 0.5 to 10 at the time of manufacturing pharmaceuticals, foods and the like.
Under a wide range of temperature and pressure of kg / cm ² (absolute pressure),
It is possible to circulate various medicinal liquids such as physiologically active substances and injectable drugs, and in the connection of the piping system of the present invention, at the time of circulating the various medicinal liquids under the above-mentioned conditions, seal them without leaking to the outside, and the piping system Impurities are prevented from entering from the outside, and the gasket component of the present invention disposed in the joint portion does not exude, and the impurities can be completely excluded from the flow products in the piping system. Further, in particular, in the piping system of the present invention, after the product is manufactured, as described above, it is necessary to manage the product under severe conditions for extremely strict cleaning, for example, 10 to 60 ° C.
Then, 0.1-10 wt% alkaline aqueous solution, saturated steam,
The alkaline aqueous solution and saturated steam may be used in combination, or nitric acid or the like may be used for cleaning. Even in these cleanings, in the piping system of the present invention, the cleaning liquid and / or gas can be tightly sealed without leaking to the outside, and deterioration of the gasket does not occur. The operation can be performed.

[0013]

EXAMPLES The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples. Example 1 (Manufacture of Gasket for Sanitary Piping) PTFE was crystallized in advance by a pressure roll and then stretched in the length direction at a stretch ratio of 110 to 300% at a temperature of less than 327 ° C. using a rubber-coated pinch roll. Porous PT with porosity of 40-86%
The FE sheet was used. The diameter of the central space shown in FIG. 3 is 2
A disc-shaped molding die 5 having a diameter of 3.2 mm and an outer diameter of 50.5 mm has an inner diameter of 23.2 mm and a thickness of 20 m.
Each of the obtained porous sheets 10 was arranged in the mold space 6 of m. Then, the mold is heated to 150 ° C., and 200 kg / cm ^{2 to} 600 kg is hydraulically applied from the upper portion 7 of the mold 5.
Pressurized at / cm ² . As a result, the porous PTFE sheet was molded into the shape of the recess 8 of the molding die 5, and at the same time, the portion of the molding die 5 corresponding to the disc portion 9 was densified.

The density of the convex portion corresponding to the concave portion 8 of the molding die 5 of each of the sanitary piping gaskets obtained as described above is almost the same as the density of the obtained porous PTFE sheet, 0.3, 0.6, 1.0, 1.2, 1.4
It was g / cm ³ , but the disk part was 1.0,
The sanitary piping gaskets having the shapes shown in FIG. 1, which were densified to 1.2, 1.3, 1.4, and 1.8 g / cm ^{3 and} had different densities of the disk portion and the convex portion, were obtained.

Example 2 Using the gaskets for sanitary piping obtained in Example 1, the compression recovery rate of the disk portion of the gasket for sanitary piping when the tightening surface pressure was set to 300 kg / cm ² was conducted by the Amsler test. It was measured by a machine. The result is 10 as shown in FIG. 4 as the relationship between the restoration rate and the density of the gasket.
It shows a restoration rate of ~ 16%, and the density of the disk is 1.2g.
Good results were obtained at / cm ³ or more.

Comparative Example 1 In the same manner as in Example 1, porous PTFE having a porosity of 90% was used.
A sheet was prepared and used to obtain a gasket for sanitary piping having a convex density of about 0.25 g / cm ³ and a disk density of 0.6 g / cm ^{3 in} the same manner as in Example 1. .. The compression recovery rate of the disk portion of the gasket for sanitary piping obtained in the same manner as in Example 2 was measured. As a result, as shown in FIG. 4, the restoration rate was as low as 6%, and the gasket after the measurement had a large deformation.

Comparative Example 2 Instead of the porous PTFE sheet of Example 1, porous P was used.
The raw material PTFE used for manufacturing the TFE sheet was heated and melted at 380 ° C. in the same molding die as in Example 1 to manufacture a PTFE gasket having the same shape. The obtained PTFE
As for the gasket, the density of the convex portion and the disc portion are both about 2.1.
It was g / cm ³ . The compression recovery rate was measured in the same manner as in Example 2. The results are shown in Fig. 4. It is clear from FIG. 4 that only a lower restoration rate can be obtained than any of the gaskets obtained in Example 1.

Example 3 Density of convex portions obtained in the same manner as in Example 1 1.0 g / cm
^{In 3} , a 1-inch identically shaped sanitary piping gasket having a disk portion density of 1.3 g / cm ³ was provided in a part of the saturated steam piping system shown in FIG. That is, in FIG. 5, a pipe 12 branched from the saturated steam supply pipe 11
Is connected to a T-type joint 14 via a ball valve 13.
Further, the diaphragm valve 1 is provided on one joint side of the T-shaped joint 14.
5 was connected, and the pipe 16 was connected to the other joint side. Further, a pipe 17 was further connected to the diaphragm valve. In the saturated steam pipe configured as described above, the ferrule in which the 1-inch gasket is arranged is installed at the connecting portion 18 between the diaphragm valve 15 and the T-type joint 14, and 1.9 is set.
Steam at a pressure of kg / cm ² was passed at a frequency of 2 to 4 times a week for about 2 hours each. This operation was continued for 6 months. During this period, the gasket placed every month was taken out and inspected, and then placed again at the same position and repeatedly used, but no steam leaked in particular. Also,
No particular change or abnormality was observed in the shape or appearance of the gasket that was taken out and inspected.

Comparative Example 3 Example 3 was repeated except that the porous PTFE gasket obtained in Comparative Example 1 was placed in the ferrule and installed in the connecting portion 18.
Saturated steam was circulated in the same manner as in. As a result, the gasket itself was poor in shape retention, and the mounting work was difficult. Further, the gasket after pressurizing was deformed to the inner and outer diameter sides, so that it could not be used continuously.

Example 4 The same 1-inch sanitary piping gasket as in Example 3 was immersed in a 2 wt% caustic soda alkaline aqueous solution for 1 week, washed with water, and then placed in the piping system shown in FIG. That is, in FIG. 6, a filter 22 loaded with a filter medium 30 for removing dust and the like in the chemical liquid is connected to the chemical liquid supply pipe 21, and a pipe 23 and a T-shaped joint 25 connected to the outlet side of the filter 22. And are connected via a diaphragm valve 24. A steam supply pipe 27 is connected to one joint side of the T-shaped joint 25 via a diaphragm valve 26,
Further, a chemical liquid discharge pipe 28 is connected to the other joint side.
In the piping system configured as described above, the ferrule in which the 1-inch sanitary piping gasket was arranged was installed in the connection portion 29 between the T-type joint 25 and the chemical liquid discharge pipe 28. This piping system is first autoclaved with high-pressure saturated steam, and then the chemical solution is continuously squeezed from the piping 21 to 1
Supplied for hours. Further, no contamination of impurities was observed in the chemical liquid flowing through the piping system and discharged. After that, the gasket was taken out from the connection portion 29, the same alkali immersion and water washing as described above were performed again, and the operation of deploying the same in the above piping system was repeated once a week for 6 months.
As a result, even after 6 months of operation, there is no leakage of steam or chemicals or sticking of the gasket to the ferrule, and the gasket after use has elasticity,
No abnormal deformation was observed. In addition, no impurities were mixed into the drug solution.

Comparative Example 4 The PTFE gasket obtained in Comparative Example 2 was immersed in an alkaline aqueous solution in the same manner as in Example 4, then washed with water, placed on the ferrule and placed in the connecting portion 29, and after autoclave sterilization,
The chemical solution was distributed. As a result, the gasket had a local abnormal deformation due to the creep phenomenon, and when repeatedly used, it did not come into close contact with the flange surface, resulting in leakage of steam and chemicals.

Comparative Example 5 A commercially available silicone resin gasket was used in Example 4
After immersing in an alkaline aqueous solution in the same manner as above, water washing was performed, the ferrule was placed on the ferrule, and the connection portion 29 was set. As a result, when the gasket was taken out from the connection part 29 after the first operation, a part of the silicon gasket adhered to the pipe ferrule part, and the gasket surface was peeled off, and repeated use was impossible.

As is clear from the above-mentioned examples and comparative examples, the sanitary piping gasket of the present invention has a high restoration rate against the tightening pressure of the joint portion, is excellent in shape recovery force, and can be used even when it is repeatedly used a plurality of times. Also has excellent sealing properties. Further, it has high durability against superheated steam and alkali, and even if it is repeatedly washed and used, the gasket does not adhere to the fitting and the impurities are not mixed into the circulating chemical solution. On the other hand, the conventional PTFE gasket and the porous PTFE gasket out of the specific range of the present invention have a low recovery rate against the applied pressure, and there is gas leakage from the beginning, or gas is already discharged after repeated use several times. A leak has occurred. In addition, it can be seen that in the conventional commercially available silicone resin gasket, the gasket is fixed to the fitting and the impurities are mixed into the flowing liquid.

[0024]

Industrial Applicability The gasket for sanitary piping of the present invention does not elute impurities into the production equipment for pharmaceuticals and the like, and is suitable for sealing the connection flange of the piping of those equipment. In addition, it has excellent resistance to high temperatures and chemicals such as acids and alkalis, and also has high elasticity and excellent compression restoring force. It is extremely useful industrially without leaking.

[Brief description of drawings]

FIG. 1 is a plan view and a cross-sectional explanatory view of an embodiment of a gasket for sanitary piping of the present invention.

FIG. 2 is a sectional explanatory view of another embodiment of the gasket for sanitary piping of the present invention.

FIG. 3 is a cross-sectional explanatory view of a molding die used for manufacturing a gasket for sanitary piping in the example of the present invention.

FIG. 4 is a diagram showing the relationship between the density of the disc portion of the gasket for sanitary piping of the present invention and the restoration rate associated with compression due to surface pressure.

FIG. 5 is an explanatory diagram of a saturated steam distribution piping system used in one embodiment of the present invention.

FIG. 6 is an explanatory diagram of a chemical liquid distribution piping system used in one embodiment of the present invention.

[Explanation of symbols]

1 Sanitary Piping Gasket 2 Disc Part 3 Convex Part 4 Hook 5 Mold 6 Mold Space 7 Upper Part 8 Recess 9 Disc Part 10 Porous Sheet 11, 12, 16, 17, 21, 23, 27, 28 Piping 13 Ball valve 15, 24, 26 Diaphragm valve 18, 19 Joint part 22 Filter 30 Filter material

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Takahisa Ueda Inventor Takahisa Ueda No. 541, Shimouchi-jin, Sanda City, Hyogo Prefecture Japan Pillar Industry Co., Ltd. Mita Factory (72) Inventor Takashi Murakami Nonaka, Yodogawa-ku, Osaka-shi, Osaka Minami 2-chome 11-48 Nippon Pillar Industry Co., Ltd.

Claims (2)

[Claims] 1. A sanitary pipe gasket, which is a disc annular body having a predetermined thickness which is concentrically cut through a central portion, and which has concavities concentric with the annular body and which has convex portions above and below the disc portion. The density of the disk part is 1.0 to 1.9 g / cm
^{3. A} sanitary pipe gasket integrally formed of porous polytetrafluoroethylene so that the density of the protrusions is 0.3 to 1.4 g / cm ³ . 2. A disk annular body having a predetermined thickness which is hollowed out concentrically in a central portion, and is provided in a molding die which is formed concentrically with the annular body and has convex portions above and below the disk portion. , Arranging a porous polytetrafluoroethylene sheet having a density of 0.3 to 1.4 g / cm ³ and a thickness of 1 to 10 mm,
The method for manufacturing a gasket for sanitary piping according to claim 1, wherein the gasket is formed by locally pressing in the thickness direction of the sheet at room temperature or by heating and molding.