JP6320680B2 - Fluororesin gasket for piping seal - Google Patents

Description

  The present invention relates to a fluororesin gasket for piping sealing. More specifically, for example, the present invention relates to a fluororesin gasket for piping seal that can be suitably used as a piping sealing material or the like in a connection portion between piping.

  Generally, gaskets such as fluororesin gaskets, metal jacket gaskets, and spiral wound gaskets are used as piping sealing materials. When a gasket is attached and tightened during piping, the flange is often not smooth. In particular, since the glass-lined flange is repeatedly sintered, the waviness of the flange is large. Therefore, the waviness of the flange needs to be absorbed by the gasket. The gasket is preferably a soft sheet in order to absorb waviness of the flange, but on the other hand, the mechanical strength decreases as it becomes softer.

  Therefore, as a fluororesin sheet with a filler that achieves both high stress relaxation and high airtightness (sealing performance) even when the filling rate of the fluororesin is low and the filling rate of the filler is high, for example, graphite, carbon There has been proposed a fluororesin sheet containing a filler in which a filler such as a carbon filler such as black, an inorganic filler such as talc, a resin powder, or a fiber material such as carbon fiber is blended (for example, patent document). 1).

  The fluororesin sheet has high stress relaxation properties and high air tightness, but since the compression rate is small, a gap is formed between the flange and the gasket, and gas or liquid in the pipe may leak from the gap. .

  Therefore, in recent years, development of a fluororesin gasket for pipe sealing that has a high compression ratio when compressed and excellent sealing properties has been desired.

JP 2007-253519 A

  This invention is made | formed in view of the said prior art, and makes it a subject to provide the fluororesin gasket for piping seals with the high compression rate when compressed and excellent in sealing performance.

The present invention is a fluororesin gasket used for sealing a connection portion between pipes, containing a fluororesin and a filler, and a filler having an average particle diameter of 40 to 150 μm is used as the filler. , 10 to 60% by weight the content of the filler, the glass particles as a filler, fluorine pipe seal, characterized in that used silicon carbide particles and alumina particles children or we selected particles The present invention relates to a resin gasket.

  ADVANTAGE OF THE INVENTION According to this invention, the compressibility when compressed and the fluororesin gasket for piping seals which was excellent in the sealing performance are provided.

  As described above, the fluororesin gasket for piping seal of the present invention is a gasket used for sealing a connection portion between pipes, contains a fluororesin and a filler, and has an average particle diameter as the filler. A filler of 30 to 150 μm is used, and the content of the filler is 5 to 60% by mass.

  The fluororesin gasket for piping seal of the present invention can be produced by, for example, molding a gasket-forming resin composition containing a fluororesin and a filler into a sheet shape.

  The resin composition for forming a gasket used in the present invention contains a fluororesin and a filler.

  Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene copolymer. Polymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), and the like are exemplified, but the present invention is limited only to such examples. It is not something. These fluororesins may be used alone or in combination of two or more. Among these fluororesins, polytetrafluoroethylene (PTFE) is preferable from the viewpoints of moldability and processability.

  The fluororesin may be in the form of a powder or may be a dispersion in which a fluororesin powder is dispersed in a solvent. The dispersion of the fluororesin powder has an advantage that the filler can be easily and uniformly dispersed.

  In the present invention, a filler having an average particle diameter of 30 to 150 μm is used as the filler.

  Fillers can be broadly classified into inorganic fillers and organic fillers. The inorganic filler and the organic filler may be used alone or in combination.

  Examples of the inorganic filler include silica particles, alumina particles, silicon carbide particles, silicon nitride particles, boron nitride particles, calcium silicate particles, aluminum silicate particles, calcium sulfate particles, barium sulfate particles, magnesium carbonate particles, glass particles, metal Although particles etc. are mentioned, this invention is not limited only to this illustration. These inorganic fillers may be used alone or in combination of two or more.

  Examples of the organic filler include polyester resin particles, polyamide resin particles, acrylic resin resin particles, polystyrene resin particles, vinyl chloride resin resin particles, vinyl acetate resin resin particles, phenol resin resin particles, and epoxy. Resin particles such as resin resin particles, silicone resin particles, polyurethane resin particles, and the like may be mentioned, but the present invention is not limited to such examples. These organic fillers may be used alone or in combination of two or more.

  The average particle diameter of the filler is 30 μm or more, preferably 40 μm or more, more preferably 50 μm or more from the viewpoint of increasing the compression ratio when the gasket is compressed, and the sealability is improved although it varies depending on the thickness of the gasket. From the viewpoint of making it, 150 μm or less, preferably 120 μm or less, and more preferably 100 μm or less.

  In addition, the average particle diameter of a filler means the volume average particle diameter when measured by the Coulter counter method. In the Coulter counter method, an electrolyte in which a filler is suspended is passed through pores, and the particle diameter is measured by reading a change in voltage pulse generated in proportion to the volume of the filler. It is a method, and the volume distribution histogram of the filler is obtained by measuring the voltage pulse height one by one.

  In the present invention, the particle size of the filler is determined by using a particle size distribution measuring device (product number: Multisizer 4) manufactured by Beckman Coulter, using ISOTON (registered trademark) II as a dispersion medium, an aperture diameter of 20 μm, and a dispersant. Is the value when ethanol is used and the sonication time is adjusted to 3 minutes.

  The content of the filler in the gasket is 5% by mass or more, preferably 10% by mass or more from the viewpoint of increasing the compression rate when the gasket is compressed, and 60% by mass from the viewpoint of suppressing the embrittlement of the gasket. Hereinafter, it is preferably 55% by mass or less, more preferably 50% by mass or less.

  The gasket-forming resin composition used in the present invention may contain a filler other than the filler as long as the purpose is not impaired. As other fillers, for example, graphite, carbon black, talc, mica, clay, calcium carbonate, magnesium oxide, etc., inorganic fine particles having an average particle diameter of less than 30 μm, carbon nanotubes, glass fibers, carbon fibers, aramid fibers, Although short fibers, such as rock wool, are mentioned, this invention is not limited only to this illustration. These other fillers may be used alone or in combination of two or more.

  The gasket-forming resin composition used in the present invention contains an appropriate amount of a processing aid for expanding the fluororesin when the gasket-forming resin composition is formed into a sheet and the preform is rolled. You may let them. Examples of the processing aid include petroleum hydrocarbon compounds such as paraffinic hydrocarbon compounds, but the present invention is not limited to such examples. Processing aids are readily available commercially. As processing aids that can be easily obtained commercially, for example, Isopar C, Isopar E, Isopar G, Isopar H, Isopar L, Isopar M [above, ExxonMobil Corp., trade name] etc. Although mentioned, this invention is not limited only to this illustration.

  The gasket-forming resin composition includes, for example, a terpene resin, a terpene-phenol resin, a coumarone resin, a coumarone-indene resin, a tackifier such as rosin, an ultraviolet absorber, and the like within a range that does not hinder the object of the present invention. Antioxidants, polymerization inhibitors, fillers, colorants such as pigments, and the like may be contained in appropriate amounts.

  The resin composition for forming a gasket has a uniform composition in which a fluororesin, a filler, and if necessary, other fillers, processing aids, additives and the like are divided into a plurality of times in an arbitrary order at once or in small portions. Can be prepared by mixing. In order to obtain a gasket-forming resin composition having a uniform composition, after adding a processing aid to the gasket-forming resin composition in an excessive amount and stirring sufficiently, It may be removed by means such as filtration, volatilization.

  The fluororesin gasket for piping seal of the present invention can be produced, for example, by molding a gasket-forming resin composition into a sheet by extrusion molding or the like. If necessary, the obtained fluororesin gasket for piping seal can be volatilized and removed from processing aids contained in the gasket by leaving it at room temperature or appropriately heating it.

  Moreover, the fluororesin gasket for piping seal of the present invention can be fired by heating at a temperature equal to or higher than the melting point of the fluororesin. The heating temperature varies depending on the type of fluororesin and cannot be determined unconditionally. However, from the viewpoint of uniformly firing the entire sheet and avoiding decomposition of the fluororesin, it is usually about 340 to 370 ° C. Is preferred.

  The fluororesin gasket for piping seal fired as described above may be used as it is as a gasket, or may be used as a gasket after being cut into a desired shape.

  Since the fluororesin gasket for piping seal of the present invention has a high compressibility and excellent sealing properties, it can be suitably used as, for example, a piping sealing material at a connection portion between piping.

EXAMPLES Next, although this invention is demonstrated further in detail based on an Example, this invention is not limited only to this Example. In addition, Example 1 , 6, and 10 are handled as a reference example.

Example 1
Glass particles (average particle diameter: 50 μm) are used as the filler, and the filler (glass particles) and polytetrafluoroethylene (PTFE) so that the content of the filler (glass particles) in the gasket is 5% by mass. Fine powder [Daikin Kogyo Co., Ltd., product number: F104] was mixed, and 1350 g of the obtained mixture was mixed with hydrocarbon organic solvent [ExxonMobil Co., Ltd., trade name: Isopar G] 250 g with a kneader. After mixing for a minute, the preform was extruded by an extruder having a die opening size of 300 mm × 20 mm.

  Next, the preform obtained above was adjusted to a linear pressure during rolling of 10 kN / m, a roll speed of 6 m / min, a roll temperature of room temperature (about 25 ° C.), and a biaxial roll (roll Diameter: 700 mm, roll interval: 20 mm), biaxial roll (roll diameter: 700 mm, roll interval: 10 mm), biaxial roll (roll diameter: 700 mm, roll interval: 5 mm) and biaxial roll ( A sheet having a thickness of 3 mm was produced by sequentially passing through a roll diameter of 700 mm and a roll interval of 3 mm.

  The sheet obtained above was allowed to stand for 24 hours in an atmosphere of room temperature (about 25 ° C.) to volatilize and remove the solvent contained in the sheet. Then, the sheet was placed in an electric furnace, and the sheet was placed at 350 ° C. for 3 hours. By baking, a sheet-like gasket having a thickness of 3 mm was obtained.

  Next, as the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined based on the following methods. The results are shown in Table 1.

(1) Compression rate The compression rate when a pressure of 34.3 MPa was applied in accordance with JIS R3453 was measured and evaluated based on the following evaluation criteria.
(Evaluation criteria)
◎: Compression rate is 20% or more ○: Compression rate is 15% or more ×: Compression rate is less than 15%, or gasket is difficult to manufacture due to embrittlement

(2) Sealing property A gasket test piece punched to an inner diameter of 48 mm and an outer diameter of 67 mm is mounted between steel flanges having a diameter of 100 mm, a height of 50 mm, and a surface roughness R _{max of} 12 μm. The load was applied so that After applying a pressure of 20 MPa with nitrogen gas from the pressure introducing through hole provided in the flange to the inner diameter side of the gasket test piece, the pressure introducing pipe was sealed and the state was maintained for 1 hour. The pressure change before and after holding was read with a pressure sensor, the amount of leakage was determined from the amount of pressure drop, and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: Leakage amount is less than 1.7 × 10 ⁻⁵ Pa · m ³ / s ○: Leakage amount is 1.7 × 10 ⁻⁵ Pa · m ³ / s or more, 3.5 × 10 ⁻⁵ Pa · m ³ Less than / s ×: Leakage is 3.5 × 10 ⁻⁵ Pa · m ³ / s or more, or it is difficult to produce a gasket due to embrittlement

Example 2
In Example 1, a sheet-like gasket was obtained by performing the same operation as in Example 1 except that the content of the filler (glass particles) in the gasket was adjusted to 10% by mass. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 3
In Example 1, a sheet-like gasket was obtained by performing the same operation as in Example 1 except that the content of the filler (glass particles) in the gasket was adjusted to 20% by mass. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 4
In Example 1, a sheet-like gasket was obtained by performing the same operation as in Example 1 except that the content of the filler (glass particles) in the gasket was adjusted to 50% by mass. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 5
In Example 1, a sheet-like gasket was obtained by performing the same operation as in Example 1 except that the content of the filler (glass particles) in the gasket was adjusted to 60% by mass. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 6
In Example 1, glass particles (average particle diameter: 30 μm) were used as the filler, and the same as Example 1 except that the content of the filler (glass particles) in the gasket was adjusted to 20% by mass. By performing the above operations, a sheet-like gasket was obtained. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 7
In Example 1, glass particles (average particle diameter: 100 μm) were used as the filler, and the same as Example 1 except that the content of the filler (glass particles) in the gasket was adjusted to 20% by mass. By performing the above operations, a sheet-like gasket was obtained. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 8
In Example 1, implementation was performed except that silicon carbide particles (average particle diameter: 50 μm) were used instead of glass particles as the filler, and the content of the filler (silicon carbide particles) in the gasket was adjusted to 10% by mass. By performing the same operation as in Example 1, a sheet-like gasket was obtained. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 9
In Example 1, alumina particles (average particle diameter: 50 μm) were used as the filler instead of glass particles, and the content of the filler (alumina particles) in the gasket was adjusted to 10 mass%. A sheet-like gasket was obtained by performing the same operation as in Example 1. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 10
In Example 1, silica particles (average particle diameter: 50 μm) were used as the filler instead of glass particles, and the content of the filler (silica particles) in the gasket was adjusted to 10 mass%. A sheet-like gasket was obtained by performing the same operation as in Example 1. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1
In Example 1, a sheet-like gasket was obtained by performing the same operation as in Example 1 except that the content of the filler (glass particles) in the gasket was adjusted to 3% by mass. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2
In Example 1, a sheet-like gasket was obtained by performing the same operation as in Example 1 except that the content of the filler (glass particles) in the gasket was adjusted to 70% by mass. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3
Example 1 is the same as Example 1 except that glass particles (average particle size: 10 μm) are used as the filler and the content of the filler (glass particles) in the gasket is adjusted to 20% by mass. By performing the above operations, a sheet-like gasket was obtained. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 4
In Example 1, glass particles (average particle diameter: 200 μm) were used as the filler, and the same as Example 1 except that the content of the filler (glass particles) in the gasket was adjusted to 20% by mass. By performing the above operations, a sheet-like gasket was obtained. As the physical properties of the sheet-like gasket obtained above, the compressibility and the sealing property were examined in the same manner as in Example 1. The results are shown in Table 1.

  From the results shown in Table 1, it can be seen that each of the gaskets obtained in each example has a high compression ratio and excellent sealing properties as compared with the gasket obtained in each comparative example. .

Claims (1)

A fluororesin gasket used for sealing a connection portion between pipes, containing a fluororesin and a filler, and a filler having an average particle diameter of 40 to 150 μm is used as the filler, and the filler content of from 10 to 60 wt%, glass particles, the pipe sealing fluororesin gasket, characterized in that used silicon carbide particles and alumina particles children or we selected particles as the filler.