WO2023120571A1 - Fluororesin gasket and production method therefor - Google Patents

Fluororesin gasket and production method therefor Download PDF

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Publication number
WO2023120571A1
WO2023120571A1 PCT/JP2022/047091 JP2022047091W WO2023120571A1 WO 2023120571 A1 WO2023120571 A1 WO 2023120571A1 JP 2022047091 W JP2022047091 W JP 2022047091W WO 2023120571 A1 WO2023120571 A1 WO 2023120571A1
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Prior art keywords
gasket
fluororesin
less
thickness
preform
Prior art date
Application number
PCT/JP2022/047091
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French (fr)
Japanese (ja)
Inventor
清華 戸田
真也 黒河
Original Assignee
株式会社バルカー
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Application filed by 株式会社バルカー filed Critical 株式会社バルカー
Priority to CN202280058667.XA priority Critical patent/CN117897570A/en
Publication of WO2023120571A1 publication Critical patent/WO2023120571A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
    • B29C55/18—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets by squeezing between surfaces, e.g. rollers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J15/00—Sealings
    • F16J15/02—Sealings between relatively-stationary surfaces
    • F16J15/06—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
    • F16J15/10—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a fluororesin gasket and its manufacturing method. More particularly, the present invention relates to a fluororesin gasket that can be suitably used in applications requiring thin gaskets, such as pumps and valves, and a method for producing the same.
  • Fluororesin gaskets are used for flanges, etc., due to their chemical resistance, heat resistance, non-adhesiveness, and low wear.
  • fluororesins, fillers, and processing aids have been proposed.
  • a petroleum-based hydrocarbon solvent having a fractionation temperature of 120° C. or less is used as the processing aid when rolling the sheet-forming resin composition containing the agent using a rolling roll having a roll temperature of 40 to 80° C.
  • a method for producing a filled fluororesin sheet using a processing aid containing 30% by mass or more (see, for example, Patent Documents 1 and 2), fluororesin, powder filler A, powder filler B, and processing aid A step of preparing a sheet-forming resin composition by mixing and rolling the sheet-forming resin composition with a rolling roll having a roll temperature of 40 to 80 ° C., cumulative in the particle size distribution of the powder filler A
  • the particle size D A (50) when the number is 50% and the particle size D B (50) when the cumulative number in the particle size distribution of the powder filler B is 50 % are expressed by the formula (1): D B (50) ⁇ 0.73 D A (50) (1) and the volume V A of the powder filler A and the volume V B of the powder filler B are represented by the formula (2): 1 ⁇ V A /V B ⁇ 3 (2)
  • a method for manufacturing a filler-filled fluororesin sheet using a processing aid that satisfies the relationship represented by Patent Document 3) has been proposed.
  • the method for producing a filler-containing fluororesin sheet it is possible to produce a fluororesin sheet having excellent stress relaxation properties and airtightness (sealing properties) even when the filling rate of the filler is high. .
  • the present invention provides a fluororesin gasket that can be suitably used in equipment such as pump casings where a thin gasket is required, and the thickness of the gasket is 0.8 mm or less.
  • An object of the present invention is to provide a fluororesin gasket capable of ensuring high airtightness (sealing property) between the gasket and a flange.
  • the present invention (1) A fluororesin gasket containing a fluororesin and a filler, having a thickness of 0.8 mm or less, a surface roughness Ra of 2.1 ⁇ m or less, and a compactness of 0.920 or more.
  • a fluororesin gasket characterized by (2) A method for producing a fluororesin gasket according to (1) above, wherein a preform containing a fluororesin and a filler and having a thickness of 20 to 200 mm is used, and the thickness is 0.8 mm.
  • a method for manufacturing a fluororesin gasket characterized by repeating rolling of the preform until the surface roughness Ra is 2.1 ⁇ m or less and the density is 0.920 or more, and (3) rolling the preform.
  • a fluororesin gasket capable of ensuring high airtightness (sealing property) between the gasket and the flange while the thickness of the gasket is 0.8 mm or less.
  • the fluororesin gasket of the present invention contains a fluororesin and a filler, has a thickness of 0.8 mm or less, and has a surface roughness Ra of 2.1 ⁇ m or less. and a compactness of 0.920 or more. According to the fluororesin gasket of the present invention, it is possible to ensure high airtightness (sealing property) with respect to the flange while the thickness of the gasket is 0.8 mm or less.
  • the thickness of the fluororesin gasket is 0.8 mm or less, when the gasket is installed between the flanges and the flanges are tightened, the compression ratio of the gasket is low due to the thin thickness of the gasket. Airtightness (sealing property) at the interface between the gasket and the flange is inevitably degraded compared to gaskets having a thickness greater than 0.8 mm.
  • the thickness of the gasket is 0.8 mm or less
  • the high airtightness (sealing property) is mainly due to the gasket
  • the surface roughness Ra of the gasket is 2.1 ⁇ m or less
  • the denseness of the gasket is 0.920 or more.
  • the fluororesin gasket of the present invention can ensure high airtightness (sealing property) even though the thickness of the fluororesin gasket is 0.8 mm or less.
  • Equipment WHEREIN It can be used suitably for the use where a gasket with thin thickness is required.
  • the fluororesin gasket of the present invention contains, for example, a fluororesin and a filler, uses a preform having a thickness of 20 to 200 mm, and has a thickness of 0.8 mm or less and a surface roughness Ra of 2.1 ⁇ m or less. , by repeating rolling of the preform until the compactness reaches 0.920 or more.
  • a gasket-forming resin composition containing a fluororesin and a filler can be used as a raw material for a fluororesin gasket.
  • fluororesins examples include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer polymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), etc., but the present invention is limited only to such examples. not something.
  • PTFE polytetrafluoroethylene
  • PFA tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer
  • FEP tetrafluoroethylene-hexafluoropropylene copolymer
  • ETFE tetrafluoroethylene-ethylene copolymer polymer
  • PVDF polyvinylidene fluoride
  • the fluororesin can usually be used in the form of a powder, but it can also be used in the form of a dispersion of fluororesin powder in which the fluororesin is dispersed in a dispersion medium.
  • a dispersion of fluororesin powder has the advantage that a component such as a filler can be easily and uniformly dispersed in the dispersion.
  • fillers include carbon-based fillers such as graphite, carbon black, expanded graphite, activated carbon, and carbon nanotubes; inorganic powders such as silicon carbide, talc, mica, clay, calcium carbonate, and magnesium oxide; and resins such as polyphenylene sulfide.
  • carbon-based fillers such as graphite, carbon black, expanded graphite, activated carbon, and carbon nanotubes
  • inorganic powders such as silicon carbide, talc, mica, clay, calcium carbonate, and magnesium oxide
  • resins such as polyphenylene sulfide.
  • powder such as powder, glass fiber, carbon fiber, aramid fiber, and short fiber such as rock wool, but the present invention is not limited to these examples. These fillers may be used alone or in combination of two or more.
  • the particle size of the powdery filler is not particularly limited, but from the viewpoint of improving the mechanical strength of the fluororesin gasket, it is preferably 1 ⁇ m or more, more preferably 2 ⁇ m or more, and still more preferably 3 ⁇ m or more. From the viewpoint of improving the smoothness of the gasket surface, the thickness is preferably 100 ⁇ m or less, more preferably 80 ⁇ m or less, and even more preferably 30 ⁇ m or less.
  • the particle size of the powdery filler means the particle size measured by the Coulter Counter method. In the Coulter counter method, an electrolyte in which a filler is suspended is passed through an aperture, and the particle size is measured by reading the change in voltage pulse generated in proportion to the volume of the filler at that time. The method.
  • the fiber length of the fibrous filler is not particularly limited, but from the viewpoint of improving the mechanical strength and surface smoothness of the fluororesin gasket, it is preferably 15 ⁇ m or less, more preferably 3 to 15 ⁇ m, and still more preferably 3 ⁇ m. ⁇ 10 ⁇ m.
  • the filler per 100 parts by mass of the fluororesin is preferably 10 to 200 parts by mass, from the viewpoint of improving the mechanical strength of the fluororesin gasket and the airtightness (sealing property) at the interface between the fluororesin gasket and the gasket. More preferably 100 to 180 parts by mass.
  • the gasket-forming resin composition contains a processing aid from the viewpoint of expanding the fluororesin in the initial step of rolling a preform obtained by molding the gasket-forming resin composition into a rod or ribbon. preferably included.
  • processing aids include petroleum hydrocarbon compounds such as paraffin hydrocarbon compounds.
  • the fractionation temperature of the processing aid is not particularly limited, it is preferably 200° C. or less, more preferably 180° C. or less from the viewpoint of allowing the processing aid to sufficiently remain in the fluororesin gasket.
  • the petroleum-based hydrocarbon compound in which the fractionation temperature of the processing aid is 200°C or less include paraffinic hydrocarbon compounds in which the fractionation temperature of the processing aid is 200°C or less. , is not limited to such examples. Processing aids having a fractional distillation temperature of 200° C. or less are readily commercially available.
  • processing aids include, for example, Exxon Mobil Company, trade names: Isopar C (fractionation temperature: 97 to 104° C.), Isopar G (fractionation temperature: 158 to 175° C.) ) and the like.
  • the amount of the processing aid per 100 parts by mass of the total amount of the fluororesin and the filler is preferably 5 to 50 parts by mass, more preferably 10 to 50 parts by mass, from the viewpoint of moderate expansion of the fluororesin when the preform is rolled. 30 parts by mass, more preferably 15 to 30 parts by mass.
  • the gasket-forming resin composition may contain, within a range that does not hinder the object of the present invention, tackifiers such as terpene resins, terpene-phenol resins, coumarone resins, coumarone-indene resins, rosin, ultraviolet absorbers, Antioxidants, polymerization inhibitors, coloring agents such as pigments and dyes may be contained in appropriate amounts.
  • tackifiers such as terpene resins, terpene-phenol resins, coumarone resins, coumarone-indene resins, rosin, ultraviolet absorbers, Antioxidants, polymerization inhibitors, coloring agents such as pigments and dyes may be contained in appropriate amounts.
  • the gasket-forming resin composition may be prepared by mixing fluororesin, filler, and, if necessary, processing aids, additives, etc., in an arbitrary order all at once or in small portions over multiple times, so as to have a uniform composition.
  • a preform is manufactured from the gasket-forming resin composition.
  • the method for producing a preform from a gasket-forming resin composition include a method for producing a preform by extrusion molding a gasket-forming resin composition, and a method for producing a preform by compression molding a gasket-forming resin composition. Examples include a method for producing a foam, but the present invention is not limited to such examples.
  • the preform is rolled with rolling rolls.
  • the preform is repeatedly rolled until the fluororesin gasket has a thickness of 0.8 mm or less, a surface roughness Ra of 2.1 ⁇ m or less, and a density of 0.920 or more.
  • One of the features of the present invention is that In the present invention, since the above operation is adopted, it is possible to obtain a fluororesin gasket capable of ensuring high airtightness (sealing property) in spite of having a thickness of 0.8 mm or less.
  • a fluororesin gasket having a thickness of 0.8 mm or less, a surface roughness Ra of 2.1 ⁇ m or less, and a compactness of 0.920 or more is used when the fluororesin sheet is compressed when the preform is rolled. It can be produced by appropriately adjusting the magnification and/or the number of times of compression.
  • Rolling of the fluororesin sheet can be performed using rolling rolls such as biaxial rolls.
  • the surface temperature of the rolling roll may be room temperature, may be higher than room temperature, or may be lower than room temperature. From the viewpoint of obtaining a fluororesin gasket capable of ensuring high airtightness (sealing property), the temperature is preferably 40 to 80°C.
  • the rolling of the preform is repeated multiple times.
  • the thickness of the preform is gradually reduced by narrowing the roll gap between the rolling rolls each time the preform is rolled, and the compression ratio and compactness of the fluororesin sheet are improved. can increase
  • the gap between the rolling rolls when rolling the preform varies depending on the thickness of the fluororesin sheet before rolling, the number of times of rolling, etc., so it cannot be generally determined, but usually the fluororesin sheet before rolling It is preferably about 40 to 60% of the thickness of the roll and the roll speed is about 3 to 10 m/min.
  • the fluororesin gasket of the present invention can be obtained, for example, by rolling a preform with a rolling roll at a compression ratio of 60 times or more, or rolling a preform with a rolling roll at a rolling number of times of 7 or more, and measuring the surface roughness Ra. It can be obtained by adjusting the density to 2.1 ⁇ m or less and the density to 0.920 or more. In the present invention, either one of the compression ratio and the number of times of rolling may be adopted, or both of them may be adopted.
  • the compression ratio of the preform should be 60 times or more from the viewpoint of producing a fluororesin gasket that can ensure high airtightness (sealing property) between the gasket and the flange while being 0.8 mm or less. is preferred.
  • the upper limit of the compression ratio of the preform is not particularly limited, but from the viewpoint of efficiently producing the fluororesin gasket of the present invention, it is preferably 500 times or less, more preferably 400 times or less. Therefore, the compression ratio of the fluororesin sheet is preferably 60 times or more, more preferably 60 to 500 times, still more preferably 60 to 400 times.
  • the preform In the range of the compression ratio of the preform, if the compression ratio is low enough to obtain a fluororesin gasket having a predetermined surface roughness Ra and a predetermined denseness, the preform is within the scope of the present invention. By increasing the number of times of rolling, it is possible to obtain a fluororesin gasket having a predetermined surface roughness Ra and a predetermined denseness.
  • the number of times the preform is rolled means the number of times the preform is rolled.
  • the number of rolling of the preform should be 6 or more from the viewpoint of producing a fluororesin gasket capable of ensuring high airtightness (sealing property) between the gasket and the flange while being 0.8 mm or less. is preferred.
  • the upper limit of the number of times the preform is rolled is not particularly limited, but from the viewpoint of efficiently producing the fluororesin gasket of the present invention, it is preferably 20 times or less, more preferably 15 times or less. Therefore, the preform is preferably rolled 6 times or more, more preferably 6 to 20 times, and still more preferably 6 to 15 times.
  • the preform In the range of the number of rolling times of the preform, if the number of rolling times is small enough to obtain a fluororesin gasket having a predetermined surface roughness Ra and a predetermined denseness, the preform can be rolled within the scope of the present invention. By increasing the compression ratio, it is possible to obtain a fluororesin gasket having a predetermined surface roughness Ra and a predetermined compactness.
  • the surface roughness Ra is 2.1 ⁇ m or less, and the density is 0.920 or more, the surface roughness Ra is 2.1 ⁇ m. or less, and a fluororesin gasket having a compactness of 0.920 or more is obtained.
  • the thickness, surface roughness Ra and compactness of the fluororesin gasket are all values at room temperature (approximately 25°C).
  • the surface roughness Ra of the fluororesin gasket means the arithmetic mean roughness Ra specified in JIS B0601 (2013).
  • the surface roughness Ra of the fluororesin gasket is from the viewpoint of obtaining a fluororesin gasket that can ensure high airtightness (sealing property) between the gasket and the flange while the thickness of the gasket is 0.8 mm or less. Therefore, it is 2.1 ⁇ m or less, preferably 2.09 ⁇ m or less.
  • the lower limit of the surface roughness Ra of the fluororesin gasket is not particularly limited, it is preferably small.
  • the above-mentioned "density of the fluororesin gasket obtained from the true density of each nonvolatile component contained in the fluororesin gasket” is, specifically, the true density of each nonvolatile component contained in the fluororesin gasket and the fluororesin
  • the formula: [Density of fluororesin gasket obtained from the true density of each non-volatile component contained in the fluororesin gasket] ⁇ (Dm ⁇ Cm)/100
  • Dm is the true density of the specific non-volatile component constituting the fluororesin gasket
  • Cm is the content (% by mass) of the specific non-volatile component in all the non-volatile components constituting the fluororesin gasket
  • Means the value obtained by the formula represented by The true density of the specific non-volatile component is, for example, 2.2 g/cm 3 for polytetrafluoroethylene (PTFE), 2.6 g/cm 3 for fine powder clay, and 3.2
  • the denseness of the fluororesin gasket is ideally the same as the density of the fluororesin gasket obtained from the true density of each non-volatile component contained in the fluororesin gasket.
  • the denseness of the fluororesin gasket is usually a smaller value than the density of the fluororesin gasket obtained from the true density of each non-volatile component contained in the fluororesin gasket. The denseness of the fluororesin gasket changes depending on the compression ratio and the number of compressions of the preform, and tends to increase as the compression ratio of the preform increases and the number of compressions increases.
  • the density of a fluororesin gasket can be obtained by measuring the mass and volume of the fluororesin gasket.
  • the density of a fluororesin gasket obtained from the true density of each non-volatile component contained in the fluororesin gasket can be obtained by separating each non-volatile component from the fluororesin gasket, determining the true density of each non-volatile component It can be determined by measuring the content of each non-volatile component.
  • the denseness of the fluororesin gasket is: 0.920 or more.
  • the upper limit of the denseness of the fluororesin gasket is not particularly limited, the higher the density, the better.
  • the fluororesin gasket obtained above may be left at room temperature or heated as appropriate to volatilize and remove the processing aid contained in the laminated sheet.
  • the fluororesin gasket can be baked by heating at a temperature higher than the melting point of the fluororesin.
  • the heating temperature varies depending on the type of fluororesin and cannot be determined unconditionally, but from the viewpoint of uniformly baking the fluororesin gasket and avoiding decomposition of the fluororesin, it is usually about 340 to 370°C. Preferably.
  • the fluororesin gasket of the present invention may be used as it is, or may be used after being cut into a desired shape and size.
  • the thickness of the fluororesin gasket of the present invention varies depending on the application of the fluororesin gasket, but high airtightness (sealing property) is ensured even if the thickness of the fluororesin gasket of the present invention is thin. It is preferably 0.8 mm or less from the viewpoint of sufficiently exhibiting the property of being able to
  • the fluororesin gasket of the present invention can ensure high airtightness (sealing property) in spite of its thickness being 0.8 mm or less. In equipment, it can be suitably used for applications where a gasket with a small thickness is required.
  • Examples 1-7 and Comparative Examples 1-3 Polytetrafluoroethylene (PTFE) fine powder [manufactured by Daikin Industries, Ltd., product number: F104] 1000 g, fine powder clay as a filler [manufactured by Showa KDE Co., Ltd., product number: NK-300] 1450 g (Example 1- 6 and Comparative Examples 1 to 3) or silicon carbide [manufactured by Showa Denko K.K., product number: #1200] 1450 g (used in Example 7), processing aid [manufactured by ExxonMobil, product name: Isopar C] After mixing 125 g and 125 g of a processing aid [manufactured by ExxonMobil, trade name: Isopar G] in a kneader for 5 minutes, the resulting mixture was extruded in an extruder having a rectangular die opening size of 300 mm x 20 mm. Preforms having the thicknesses shown in Table
  • the preform obtained above was run at a running speed of 6 m/min. It is passed between the rolls of the biaxial rolls, successively passed between the rolls of the biaxial rolls in which the gap between the rolls of the biaxial rolls is gradually narrowed, and rolled, and finally the fluororesin shown in Table 1.
  • a fluororesin gasket was obtained by passing between rolls of biaxial rolls having a gap corresponding to the thickness of the gasket and rolling. The number of times the preform is rolled by passing it between the rolls of the biaxial rolls (the number of rolling times) and the compression ratio of the preform are as shown in the manufacturing conditions column in Table 1.
  • the thickness, surface roughness and denseness of the fluororesin gasket obtained above are shown in the gasket performance column in Table 1.
  • the gasket When the leak rate is 3.0 ⁇ 10 ⁇ 4 Pa ⁇ m 3 /sec or less, the gasket satisfies the airtightness (sealing property) acceptance criteria.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
  • Gasket Seals (AREA)
  • Sealing Material Composition (AREA)

Abstract

Provided is a fluororesin gasket with which it is possible, with a gasket thickness of 0.8 mm or less, to ensure a high degree of airtightness (sealability) between flanges. This fluororesin gasket contains a fluororesin and a filler, and has a thickness of 0.8 mm or less. This fluororesin gasket has a surface roughness Ra of 2.1 μm or less and a denseness of 0.920 or more.

Description

フッ素樹脂製ガスケットおよびその製造方法Fluororesin gasket and manufacturing method thereof
　本発明は、フッ素樹脂製ガスケットおよびその製造方法に関する。さらに詳しくは、例えば、ポンプ、バルブなどの機器において、厚さが薄いガスケットが必要とされる用途に好適に使用することができるフッ素樹脂製ガスケットおよびその製造方法に関する。 The present invention relates to a fluororesin gasket and its manufacturing method. More particularly, the present invention relates to a fluororesin gasket that can be suitably used in applications requiring thin gaskets, such as pumps and valves, and a method for producing the same.
　フッ素樹脂製ガスケットは、耐薬品性、耐熱性、非粘着性および低摩耗性を有することから、フランジなどに使用されている。 　Fluororesin gaskets are used for flanges, etc., due to their chemical resistance, heat resistance, non-adhesiveness, and low wear.
　近年、フッ素樹脂の充填率が低く、充填材の充填率が高くても高い応力緩和性および高い気密性（シール性）を有するフッ素樹脂シートを製造する方法として、フッ素樹脂、充填材および加工助剤を含有するシート形成用樹脂組成物をロール温度が４０～８０℃である圧延ロールを用いて圧延する際に、前記加工助剤として分留温度が１２０℃以下である石油系炭化水素溶剤を３０質量％以上含有する加工助剤を用いる充填材入りフッ素樹脂シートの製造方法（例えば、特許文献１および特許文献２参照）、およびフッ素樹脂、粉末充填材Ａ、粉末充填材Ｂおよび加工助剤を混合してシート形成用樹脂組成物を調製する工程、およびロール温度が４０～８０℃である圧延ロールで前記シート形成用樹脂組成物を圧延する際に、粉末充填材Ａの粒度分布における累積個数が５０％のときの粒径ＤA（５０）および粉末充填材Ｂの粒度分布における累積個数が５０％のときの粒径ＤB（５０）が、式(1):
　ＤB（５０）≦０．７３ＤA（５０）　　　　　　　　　　(1)
で表される関係を満たし、粉末充填材Ａの体積ＶAおよび粉末充填材Ｂの体積ＶBが式(2):
　１≦ＶA／ＶB≦３　　　　　　　　　　　　　　　　　　(2)
で表される関係を満たし、前記加工助剤として分留温度が１２０℃以下である石油系炭化水素溶剤を３０質量％以上含む加工助剤を用いる充填材入りフッ素樹脂シートの製造方法（例えば、特許文献３参照）が提案されている。 In recent years, as a method for producing a fluororesin sheet with a low fluororesin filling rate and high stress relaxation and high airtightness (sealing properties) even with a high filler filling rate, fluororesins, fillers, and processing aids have been proposed. A petroleum-based hydrocarbon solvent having a fractionation temperature of 120° C. or less is used as the processing aid when rolling the sheet-forming resin composition containing the agent using a rolling roll having a roll temperature of 40 to 80° C. A method for producing a filled fluororesin sheet using a processing aid containing 30% by mass or more (see, for example, Patent Documents 1 and 2), fluororesin, powder filler A, powder filler B, and processing aid A step of preparing a sheet-forming resin composition by mixing and rolling the sheet-forming resin composition with a rolling roll having a roll temperature of 40 to 80 ° C., cumulative in the particle size distribution of the powder filler A The particle size D A (50) when the number is 50% and the particle size D B (50) when the cumulative number in the particle size distribution of the powder filler B is 50 % are expressed by the formula (1):
D B (50) ≤ 0.73 D A (50) (1)
and the volume V A of the powder filler A and the volume V B of the powder filler B are represented by the formula (2):
1≦V A /V B ≦3 (2)
A method for manufacturing a filler-filled fluororesin sheet using a processing aid that satisfies the relationship represented by Patent Document 3) has been proposed.
特許第４２１３１６７号公報Japanese Patent No. 4213167 特許第４７７７３８９号公報Japanese Patent No. 4777389 特許第５２２６９３８号公報Japanese Patent No. 5226938
　前記充填材入りフッ素樹脂シートの製造方法によれば、充填材の充填率が高くても応力緩和性および気密性（シール性）に優れているフッ素樹脂シートを製造することができるとされている。 According to the method for producing a filler-containing fluororesin sheet, it is possible to produce a fluororesin sheet having excellent stress relaxation properties and airtightness (sealing properties) even when the filling rate of the filler is high. .
　しかし、近年、ポンプのケーシングなどの機器に厚さが１ｍｍ以下であるフッ素樹脂製ガスケットが使用されている。当該ガスケットがフランジ間で圧縮されたとき、当該ガスケットの厚さが薄いことから当該ガスケットの圧縮率が低くなる。したがって、当該ガスケットとフランジとの界面における気密性（シール性）を十分に確保することができない。 However, in recent years, fluororesin gaskets with a thickness of 1 mm or less have been used in equipment such as pump casings. When the gasket is compressed between the flanges, the compressibility of the gasket is low due to the thin thickness of the gasket. Therefore, sufficient airtightness (sealing property) cannot be ensured at the interface between the gasket and the flange.
　本発明は、ポンプのケーシングなどの機器において、厚さが薄いガスケットが必要とされる用途に好適に使用することができるフッ素樹脂製ガスケットであって、ガスケットの厚さが０．８ｍｍ以下でありながらガスケットとフランジとの間で高い気密性（シール性）を確保することができるフッ素樹脂製ガスケットを提供することを課題とする。 The present invention provides a fluororesin gasket that can be suitably used in equipment such as pump casings where a thin gasket is required, and the thickness of the gasket is 0.8 mm or less. An object of the present invention is to provide a fluororesin gasket capable of ensuring high airtightness (sealing property) between the gasket and a flange.
　本発明は、
（１）　フッ素樹脂および充填材を含有し、厚さが０．８ｍｍ以下であるフッ素樹脂製ガスケットであって、表面粗さＲａが２．１μｍ以下であり、緻密度が０．９２０以上であることを特徴とするフッ素樹脂製ガスケット、
（２）　前記（１）に記載のフッ素樹脂製ガスケットを製造する方法であって、フッ素樹脂および充填材を含有し、厚さが２０～２００ｍｍであるプレフォームを用い、厚さが０．８ｍｍ以下、表面粗さＲａが２．１μｍ以下、緻密度が０．９２０以上となるまで当該プレフォームの圧延を繰り返すことを特徴とするフッ素樹脂製ガスケットの製造方法、および
（３）　プレフォームを圧延するときの圧延ロールの表面温度が４０～８０℃である前記（２）に記載のフッ素樹脂製ガスケットの製造方法
に関する。 The present invention
(1) A fluororesin gasket containing a fluororesin and a filler, having a thickness of 0.8 mm or less, a surface roughness Ra of 2.1 μm or less, and a compactness of 0.920 or more. A fluororesin gasket characterized by
(2) A method for producing a fluororesin gasket according to (1) above, wherein a preform containing a fluororesin and a filler and having a thickness of 20 to 200 mm is used, and the thickness is 0.8 mm. Hereinafter, a method for manufacturing a fluororesin gasket characterized by repeating rolling of the preform until the surface roughness Ra is 2.1 μm or less and the density is 0.920 or more, and (3) rolling the preform. The method for producing a fluororesin gasket according to (2) above, wherein the rolling roll has a surface temperature of 40 to 80°C.
　本発明によれば、ガスケットの厚さが０．８ｍｍ以下でありながらガスケットとフランジとの間で高い気密性（シール性）を確保することができるフッ素樹脂製ガスケットが提供される。 According to the present invention, there is provided a fluororesin gasket capable of ensuring high airtightness (sealing property) between the gasket and the flange while the thickness of the gasket is 0.8 mm or less.
　本発明のフッ素樹脂製ガスケットは、前記したように、フッ素樹脂および充填材を含有し、厚さが０．８ｍｍ以下であるフッ素樹脂製ガスケットであり、表面粗さＲａが２．１μｍ以下であり、緻密度が０．９２０以上であることを特徴とする。本発明のフッ素樹脂製ガスケットによれば、ガスケットの厚さが０．８ｍｍ以下でありながらフランジとの間で高い気密性（シール性）を確保することができる。 As described above, the fluororesin gasket of the present invention contains a fluororesin and a filler, has a thickness of 0.8 mm or less, and has a surface roughness Ra of 2.1 μm or less. and a compactness of 0.920 or more. According to the fluororesin gasket of the present invention, it is possible to ensure high airtightness (sealing property) with respect to the flange while the thickness of the gasket is 0.8 mm or less.
　フッ素樹脂製ガスケットの厚さが０．８ｍｍ以下である場合、当該ガスケットをフランジ間に設置してフランジを締め付けたとき、当該ガスケットの厚さが薄いことから当該ガスケットの圧縮率が低いため、当該ガスケットとフランジとの界面における気密性（シール性）が、厚さが０．８ｍｍよりも大きいガスケットと対比して必然的に低下する。 If the thickness of the fluororesin gasket is 0.8 mm or less, when the gasket is installed between the flanges and the flanges are tightened, the compression ratio of the gasket is low due to the thin thickness of the gasket. Airtightness (sealing property) at the interface between the gasket and the flange is inevitably degraded compared to gaskets having a thickness greater than 0.8 mm.
　これに対して、本発明のフッ素樹脂製ガスケットによれば、このようにガスケットの厚さが０．８ｍｍ以下であるにもかかわらず、高い気密性（シール性）を有するのは、主として当該ガスケットの表面粗さＲａが２．１μｍ以下であるとともに、当該ガスケットの緻密度が０．９２０以上であるという構成要件を有することに基づく。 In contrast, according to the fluororesin gasket of the present invention, although the thickness of the gasket is 0.8 mm or less, the high airtightness (sealing property) is mainly due to the gasket The surface roughness Ra of the gasket is 2.1 μm or less, and the denseness of the gasket is 0.920 or more.
　本発明のフッ素樹脂製ガスケットは、フッ素樹脂製ガスケットの厚さが０．８ｍｍ以下であるにもかかわらず、高い気密性（シール性）を確保することができることから、例えば、ポンプ、バルブなどの機器において、厚さが薄いガスケットが必要とされる用途に好適に使用することができる。 The fluororesin gasket of the present invention can ensure high airtightness (sealing property) even though the thickness of the fluororesin gasket is 0.8 mm or less. Equipment WHEREIN: It can be used suitably for the use where a gasket with thin thickness is required.
　本発明のフッ素樹脂製ガスケットは、例えば、フッ素樹脂および充填材を含有し、厚さが２０～２００ｍｍであるプレフォームを用い、厚さが０．８ｍｍ以下、表面粗さＲａが２．１μｍ以下、緻密度が０．９２０以上となるまで当該プレフォームの圧延を繰り返すことにより、製造することができる。 The fluororesin gasket of the present invention contains, for example, a fluororesin and a filler, uses a preform having a thickness of 20 to 200 mm, and has a thickness of 0.8 mm or less and a surface roughness Ra of 2.1 μm or less. , by repeating rolling of the preform until the compactness reaches 0.920 or more.
　フッ素樹脂製ガスケットの原料として、フッ素樹脂および充填材を含有するガスケット形成用樹脂組成物を用いることができる。 A gasket-forming resin composition containing a fluororesin and a filler can be used as a raw material for a fluororesin gasket.
　フッ素樹脂としては、例えば、ポリテトラフルオロエチレン（ＰＴＦＥ）、テトラフルオロエチレン－パーフルオロアルキルビニルエーテル共重合体（ＰＦＡ）、テトラフルオロエチレン－ヘキサフルオロプロピレン共重合体（ＦＥＰ）、テトラフルオロエチレン－エチレン共重合体（ＥＴＦＥ）、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリクロロトリフルオロエチレン（ＰＣＴＦＥ）、クロロトリフルオロエチレン－エチレン共重合体（ＥＣＴＦＥ）などが挙げられるが、本発明は、かかる例示のみに限定されるものではない。これらのフッ素樹脂は、それぞれ単独で用いてもよく、２種類以上を併用してもよい。これらのフッ素樹脂のなかでは、ポリテトラフルオロエチレン（ＰＴＦＥ）は、成形性および加工性を向上させる観点から好ましい。 Examples of fluororesins include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer polymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), etc., but the present invention is limited only to such examples. not something. Each of these fluororesins may be used alone, or two or more of them may be used in combination. Among these fluororesins, polytetrafluoroethylene (PTFE) is preferable from the viewpoint of improving moldability and workability.
　フッ素樹脂は、通常、粉末状で用いることができるが、フッ素樹脂を分散媒に分散させたフッ素樹脂粉末の分散液の形態で用いることもできる。フッ素樹脂粉末の分散液は、充填材などの成分を当該分散液に容易に均一に分散させることができるという利点を有する。 The fluororesin can usually be used in the form of a powder, but it can also be used in the form of a dispersion of fluororesin powder in which the fluororesin is dispersed in a dispersion medium. A dispersion of fluororesin powder has the advantage that a component such as a filler can be easily and uniformly dispersed in the dispersion.
　充填材としては、例えば、黒鉛、カーボンブラック、膨張黒鉛、活性炭、カーボンナノチューブなどの炭素系充填材、炭化ケイ素、タルク、マイカ、クレー、炭酸カルシウム、酸化マグネシウムなどの無機粉末、ポリフェニレンサルファイドなどの樹脂粉末などの粉末、ガラス繊維、炭素繊維、アラミド繊維、ロックウールなどの短繊維などが挙げられるが、本発明は、かかる例示のみに限定されるものではない。これらの充填材は、それぞれ単独で用いてもよく、２種類以上を併用してもよい。 Examples of fillers include carbon-based fillers such as graphite, carbon black, expanded graphite, activated carbon, and carbon nanotubes; inorganic powders such as silicon carbide, talc, mica, clay, calcium carbonate, and magnesium oxide; and resins such as polyphenylene sulfide. Examples include powder such as powder, glass fiber, carbon fiber, aramid fiber, and short fiber such as rock wool, but the present invention is not limited to these examples. These fillers may be used alone or in combination of two or more.
　粉末状の充填材の粒子径は、特に限定されないが、フッ素樹脂製ガスケットの機械的強度を向上させる観点から、好ましくは１μｍ以上、より好ましくは２μｍ以上、さらに好ましくは３μｍ以上であり、フッ素樹脂製ガスケットの表面の平滑性を向上させる観点から、好ましくは１００μｍ以下、より好ましくは８０μｍ以下、さらに好ましくは３０μｍ以下である。粉末状の充填材の粒子径は、コールターカウンター法で測定したときの粒子径を意味する。前記コールターカウンター法は、充填材を懸濁させた電解質を細孔（アパチャ－）に通過させ、そのときに充填材の体積に比例して発生する電圧パルスの変化を読み取って粒子径を測定する方法である。繊維状の充填材の繊維長は、特に限定されないが、フッ素樹脂製ガスケットの機械的強度および表面の平滑性を向上させる観点から、好ましくは１５μｍ以下、より好ましくは３～１５μｍ、さらに好ましくは３～１０μｍである。 The particle size of the powdery filler is not particularly limited, but from the viewpoint of improving the mechanical strength of the fluororesin gasket, it is preferably 1 μm or more, more preferably 2 μm or more, and still more preferably 3 μm or more. From the viewpoint of improving the smoothness of the gasket surface, the thickness is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 30 μm or less. The particle size of the powdery filler means the particle size measured by the Coulter Counter method. In the Coulter counter method, an electrolyte in which a filler is suspended is passed through an aperture, and the particle size is measured by reading the change in voltage pulse generated in proportion to the volume of the filler at that time. The method. The fiber length of the fibrous filler is not particularly limited, but from the viewpoint of improving the mechanical strength and surface smoothness of the fluororesin gasket, it is preferably 15 μm or less, more preferably 3 to 15 μm, and still more preferably 3 μm. ~10 μm.
　フッ素樹脂１００質量部あたりの充填材は、フッ素樹脂製ガスケットの機械的強度およびフッ素樹脂製ガスケットとガスケットとの界面における気密性（シール性）を向上させる観点から、好ましくは１０～２００質量部、より好ましくは１００～１８０質量部である。 The filler per 100 parts by mass of the fluororesin is preferably 10 to 200 parts by mass, from the viewpoint of improving the mechanical strength of the fluororesin gasket and the airtightness (sealing property) at the interface between the fluororesin gasket and the gasket. More preferably 100 to 180 parts by mass.
　ガスケット形成用樹脂組成物には、当該ガスケット形成用樹脂組成物をロッド状またはリボン状に成形することによって得られたプレフォームを圧延させる初期工程でフッ素樹脂を膨張させる観点から、加工助剤が含まれていることが好ましい。 The gasket-forming resin composition contains a processing aid from the viewpoint of expanding the fluororesin in the initial step of rolling a preform obtained by molding the gasket-forming resin composition into a rod or ribbon. preferably included.
　加工助剤としては、例えば、パラフィン系炭化水素化合物などの石油系炭化水素化合物などが挙げられる。加工助剤の分留温度は、特に限定されないが、加工助剤をフッ素樹脂製ガスケットに十分に残存させる観点から、好ましくは２００℃以下、より好ましくは１８０℃以下である。加工助剤の分留温度が２００℃以下である石油系炭化水素化合物としては、例えば、加工助剤の分留温度が２００℃以下であるパラフィン系炭化水素化合物などが挙げられるが、本発明は、かかる例示のみに限定されるものではない。分留温度が２００℃以下である加工助剤は、商業的に容易に入手することができる。商業的に容易に入手することができる加工助剤としては、例えば、エクソンモービル社製、商品名：アイソパーＣ（分留温度：９７～１０４℃）、アイソパーＧ（分留温度：１５８～１７５℃）などが挙げられる。 Examples of processing aids include petroleum hydrocarbon compounds such as paraffin hydrocarbon compounds. Although the fractionation temperature of the processing aid is not particularly limited, it is preferably 200° C. or less, more preferably 180° C. or less from the viewpoint of allowing the processing aid to sufficiently remain in the fluororesin gasket. Examples of the petroleum-based hydrocarbon compound in which the fractionation temperature of the processing aid is 200°C or less include paraffinic hydrocarbon compounds in which the fractionation temperature of the processing aid is 200°C or less. , is not limited to such examples. Processing aids having a fractional distillation temperature of 200° C. or less are readily commercially available. Commercially readily available processing aids include, for example, Exxon Mobil Company, trade names: Isopar C (fractionation temperature: 97 to 104° C.), Isopar G (fractionation temperature: 158 to 175° C.) ) and the like.
　フッ素樹脂および充填材の合計量１００質量部あたりの加工助剤の量は、プレフォームを圧延させるときにフッ素樹脂を適度に膨張させる観点から、好ましくは５～５０質量部、より好ましくは１０～３０質量部、さらに好ましくは１５～３０質量部である。 The amount of the processing aid per 100 parts by mass of the total amount of the fluororesin and the filler is preferably 5 to 50 parts by mass, more preferably 10 to 50 parts by mass, from the viewpoint of moderate expansion of the fluororesin when the preform is rolled. 30 parts by mass, more preferably 15 to 30 parts by mass.
　ガスケット形成用樹脂組成物には、本発明の目的が阻害されない範囲内で、例えば、テルペン樹脂、テルペン－フェノール樹脂、クマロン樹脂、クマロン－インデン樹脂、ロジンなどの粘着性付与剤、紫外線吸収剤、酸化防止剤、重合禁止剤、顔料、染料などの着色剤などが適量で含まれていてもよい。 The gasket-forming resin composition may contain, within a range that does not hinder the object of the present invention, tackifiers such as terpene resins, terpene-phenol resins, coumarone resins, coumarone-indene resins, rosin, ultraviolet absorbers, Antioxidants, polymerization inhibitors, coloring agents such as pigments and dyes may be contained in appropriate amounts.
　ガスケット形成用樹脂組成物は、フッ素樹脂、充填材、必要により、加工助剤、添加剤などを任意の順序で一度に、または少量ずつ複数回に分けて均一な組成を有するように混合することによって調製することができる。なお、均一な組成を有するガスケット形成用樹脂組成物を得るために、ガスケット形成用樹脂組成物に加工助剤を過剰量で添加し、十分に撹拌した後に、当該過剰量の加工助剤を、例えば、濾過、揮散などの手段によって除去してもよい。 The gasket-forming resin composition may be prepared by mixing fluororesin, filler, and, if necessary, processing aids, additives, etc., in an arbitrary order all at once or in small portions over multiple times, so as to have a uniform composition. can be prepared by In order to obtain a gasket-forming resin composition having a uniform composition, an excessive amount of a processing aid is added to the gasket-forming resin composition, and after sufficient stirring, the excessive amount of the processing aid is added, For example, it may be removed by means such as filtration and volatilization.
　次に、ガスケット形成用樹脂組成物からプレフォームを製造する。ガスケット形成用樹脂組成物からプレフォームを製造する方法としては、例えば、ガスケット形成用樹脂組成物を押出成形することによってプレフォームを製造する方法、ガスケット形成用樹脂組成物を圧縮成形することによってプレフォームを製造する方法などが挙げられるが、本発明は、かかる例示のみに限定されるものではない。 Next, a preform is manufactured from the gasket-forming resin composition. Examples of the method for producing a preform from a gasket-forming resin composition include a method for producing a preform by extrusion molding a gasket-forming resin composition, and a method for producing a preform by compression molding a gasket-forming resin composition. Examples include a method for producing a foam, but the present invention is not limited to such examples.
　プレフォームの厚さは、ガスケットの厚さは、０．８ｍｍ以下でありながらガスケットとフランジとの間で高い気密性（シール性）を確保することができるフッ素樹脂製ガスケットを作製する観点から、２０～２００ｍｍとなるように調整される。 From the viewpoint of producing a fluororesin gasket that can ensure high airtightness (sealing property) between the gasket and the flange while the thickness of the preform is 0.8 mm or less, It is adjusted to be 20 to 200 mm.
　次に、プレフォームを圧延ロールで圧延する。本発明においては、フッ素樹脂製ガスケットの厚さが０．８ｍｍ以下、表面粗さＲａが２．１μｍ以下、緻密度が０．９２０以上となるまで当該プレフォームの圧延を繰り返すという操作が採られている点に本発明の特徴の１つがある。本発明では、前記操作が採られているので、厚さが０．８ｍｍ以下であるにもかかわらず、高い気密性（シール性）を確保することができるフッ素樹脂製ガスケットを得ることができる。 Next, the preform is rolled with rolling rolls. In the present invention, the preform is repeatedly rolled until the fluororesin gasket has a thickness of 0.8 mm or less, a surface roughness Ra of 2.1 μm or less, and a density of 0.920 or more. One of the features of the present invention is that In the present invention, since the above operation is adopted, it is possible to obtain a fluororesin gasket capable of ensuring high airtightness (sealing property) in spite of having a thickness of 0.8 mm or less.
　厚さが０．８ｍｍ以下であり、表面粗さＲａが２．１μｍ以下であり、緻密度が０．９２０以上であるフッ素樹脂製ガスケットは、プレフォームを圧延する際に、フッ素樹脂シートの圧縮倍率および／または圧縮回数を適切に調整することにより、作製することができる。 A fluororesin gasket having a thickness of 0.8 mm or less, a surface roughness Ra of 2.1 μm or less, and a compactness of 0.920 or more is used when the fluororesin sheet is compressed when the preform is rolled. It can be produced by appropriately adjusting the magnification and/or the number of times of compression.
　フッ素樹脂シートの圧延は、二軸ロールなどの圧延ロールを用いて行なうことができる。圧延ロールの表面温度は、室温であってもよく、室温よりも高温であってもよく、あるいは室温よりも低温であってもよいが、厚さが０．８ｍｍ以下であるにもかかわらず、高い気密性（シール性）を確保することができるフッ素樹脂製ガスケットを得る観点から、４０～８０℃であることが好ましい。 Rolling of the fluororesin sheet can be performed using rolling rolls such as biaxial rolls. The surface temperature of the rolling roll may be room temperature, may be higher than room temperature, or may be lower than room temperature. From the viewpoint of obtaining a fluororesin gasket capable of ensuring high airtightness (sealing property), the temperature is preferably 40 to 80°C.
　プレフォームの圧延は、複数回繰り返して行なわれる。プレフォームの圧延を繰り返して行なう際、当該プレフォームの圧延を繰り返すごとに圧延ロールのロール間隔を狭くすることにより、プレフォームの厚さを徐々に薄くし、フッ素樹脂シートの圧縮倍率および緻密度を高めることができる。 The rolling of the preform is repeated multiple times. When the preform is repeatedly rolled, the thickness of the preform is gradually reduced by narrowing the roll gap between the rolling rolls each time the preform is rolled, and the compression ratio and compactness of the fluororesin sheet are improved. can increase
　プレフォームを圧延するときの圧延ロールのロール間の間隔は、圧延前のフッ素樹脂シートの厚さ、圧延回数などによって異なるので一概には決定することができないが、通常、圧延前のフッ素樹脂シートの厚さの４０～６０％程度であり、ロール速度は３～１０ｍ／ｍｉｎ程度であることが好ましい。 The gap between the rolling rolls when rolling the preform varies depending on the thickness of the fluororesin sheet before rolling, the number of times of rolling, etc., so it cannot be generally determined, but usually the fluororesin sheet before rolling It is preferably about 40 to 60% of the thickness of the roll and the roll speed is about 3 to 10 m/min.
　本発明のフッ素樹脂製ガスケットは、例えば、プレフォームを圧延ロールで６０倍以上の圧縮倍率で圧延するか、またはプレフォームを圧延ロールで７回以上の圧延回数で圧延し、表面粗さＲａを２．１μｍ以下、緻密度を０．９２０以上に調整することにより、得ることができる。なお、本発明においては、前記圧縮倍率および前記圧延回数のうち、いずれか一方のみを採用してもよく、双方を採用してもよい。 The fluororesin gasket of the present invention can be obtained, for example, by rolling a preform with a rolling roll at a compression ratio of 60 times or more, or rolling a preform with a rolling roll at a rolling number of times of 7 or more, and measuring the surface roughness Ra. It can be obtained by adjusting the density to 2.1 μm or less and the density to 0.920 or more. In the present invention, either one of the compression ratio and the number of times of rolling may be adopted, or both of them may be adopted.
　フッ素樹脂シートの圧縮倍率は、式：
［圧縮倍率（倍）］＝［初期のプレフォームの厚さ（ｍｍ）］／［フッ素樹脂製ガスケットの厚さ（ｍｍ）］
によって求められる。プレフォームの圧縮倍率は、０．８ｍｍ以下でありながらガスケットとフランジとの間で高い気密性（シール性）を確保することができるフッ素樹脂製ガスケットを作製する観点から、６０倍以上であることが好ましい。プレフォームの圧縮倍率の上限値は、特に限定されないが、本発明のフッ素樹脂製ガスケットを効率よく製造する観点から、好ましくは５００倍以下、より好ましくは４００倍以下である。したがって、フッ素樹脂シートの圧縮倍率は、好ましくは６０倍以上、より好ましくは６０～５００倍、さらに好ましくは６０～４００倍である。 The compression ratio of a fluororesin sheet is expressed by the formula:
[Compression ratio (times)] = [initial thickness of preform (mm)]/[thickness of fluororesin gasket (mm)]
sought by The compression ratio of the preform should be 60 times or more from the viewpoint of producing a fluororesin gasket that can ensure high airtightness (sealing property) between the gasket and the flange while being 0.8 mm or less. is preferred. The upper limit of the compression ratio of the preform is not particularly limited, but from the viewpoint of efficiently producing the fluororesin gasket of the present invention, it is preferably 500 times or less, more preferably 400 times or less. Therefore, the compression ratio of the fluororesin sheet is preferably 60 times or more, more preferably 60 to 500 times, still more preferably 60 to 400 times.
　なお、前記プレフォームの圧縮倍率の範囲において、所定の表面粗さＲａおよび所定の緻密度を有するフッ素樹脂製ガスケットを得るのに圧縮倍率が低い場合には、本発明の範囲内でプレフォームの圧延回数を増加させることにより、所定の表面粗さＲａおよび所定の緻密度を有するフッ素樹脂製ガスケットを得ることができる。 In the range of the compression ratio of the preform, if the compression ratio is low enough to obtain a fluororesin gasket having a predetermined surface roughness Ra and a predetermined denseness, the preform is within the scope of the present invention. By increasing the number of times of rolling, it is possible to obtain a fluororesin gasket having a predetermined surface roughness Ra and a predetermined denseness.
　プレフォームの圧延回数は、プレフォームの圧延を行なう回数を意味する。プレフォームの圧延回数は、０．８ｍｍ以下でありながらガスケットとフランジとの間で高い気密性（シール性）を確保することができるフッ素樹脂製ガスケットを作製する観点から、６回以上であることが好ましい。プレフォームの圧延回数の上限値は、特に限定されないが、本発明のフッ素樹脂製ガスケットを効率よく製造する観点から、好ましくは２０回以下、より好ましくは１５回以下である。したがって、プレフォームの圧延回数は、好ましくは６回以上、より好ましくは６～２０回、さらに好ましくは６～１５回である。 The number of times the preform is rolled means the number of times the preform is rolled. The number of rolling of the preform should be 6 or more from the viewpoint of producing a fluororesin gasket capable of ensuring high airtightness (sealing property) between the gasket and the flange while being 0.8 mm or less. is preferred. The upper limit of the number of times the preform is rolled is not particularly limited, but from the viewpoint of efficiently producing the fluororesin gasket of the present invention, it is preferably 20 times or less, more preferably 15 times or less. Therefore, the preform is preferably rolled 6 times or more, more preferably 6 to 20 times, and still more preferably 6 to 15 times.
　なお、前記プレフォームの圧延回数の範囲において、所定の表面粗さＲａおよび所定の緻密度を有するフッ素樹脂製ガスケットを得るのに圧延回数が少ない場合には、本発明の範囲内でプレフォームの圧縮倍率を高めることにより、所定の表面粗さＲａおよび所定の緻密度を有するフッ素樹脂製ガスケットを得ることができる。 In the range of the number of rolling times of the preform, if the number of rolling times is small enough to obtain a fluororesin gasket having a predetermined surface roughness Ra and a predetermined denseness, the preform can be rolled within the scope of the present invention. By increasing the compression ratio, it is possible to obtain a fluororesin gasket having a predetermined surface roughness Ra and a predetermined compactness.
　以上のようにして厚さが０．８ｍｍ以下、表面粗さＲａが２．１μｍ以下、緻密度が０．９２０以上となるまでプレフォームの圧延を繰り返すことにより、表面粗さＲａが２．１μｍ以下であり、緻密度が０．９２０以上であるフッ素樹脂製ガスケットが得られる。なお、フッ素樹脂製ガスケットの厚さ、表面粗さＲａおよび緻密度は、いずれも室温（約２５℃）における値である。 By repeating the rolling of the preform until the thickness is 0.8 mm or less, the surface roughness Ra is 2.1 μm or less, and the density is 0.920 or more, the surface roughness Ra is 2.1 μm. or less, and a fluororesin gasket having a compactness of 0.920 or more is obtained. The thickness, surface roughness Ra and compactness of the fluororesin gasket are all values at room temperature (approximately 25°C).
　フッ素樹脂製ガスケットの表面粗さＲａは、ＪＩＳ　Ｂ０６０１（２０１３）に規定されている算術平均粗さＲａを意味する。フッ素樹脂製ガスケットの表面粗さＲａは、ガスケットの厚さが０．８ｍｍ以下でありながらガスケットとフランジとの間で高い気密性（シール性）を確保することができるフッ素樹脂製ガスケットを得る観点から、２．１μｍ以下、好ましくは２．０９μｍ以下である。フッ素樹脂製ガスケットの表面粗さＲａの下限値は、特に限定されないが、小さいことが好ましい。 The surface roughness Ra of the fluororesin gasket means the arithmetic mean roughness Ra specified in JIS B0601 (2013). The surface roughness Ra of the fluororesin gasket is from the viewpoint of obtaining a fluororesin gasket that can ensure high airtightness (sealing property) between the gasket and the flange while the thickness of the gasket is 0.8 mm or less. Therefore, it is 2.1 μm or less, preferably 2.09 μm or less. Although the lower limit of the surface roughness Ra of the fluororesin gasket is not particularly limited, it is preferably small.
　フッ素樹脂製ガスケットの緻密度は、式：
［フッ素樹脂製ガスケットの緻密度（－）］＝［フッ素樹脂製ガスケットの実際の密度（ｇ／ｃｍ3）］／［フッ素樹脂製ガスケットに含まれる各不揮発成分の真密度から求められるフッ素樹脂製ガスケットの密度］
によって求められる。 Density of fluororesin gaskets is expressed by the formula:
[Density of fluororesin gasket (-)] = [Actual density of fluororesin gasket (g/cm 3 )] / [Made of fluororesin obtained from the true density of each non-volatile component contained in the fluororesin gasket Gasket density]
sought by
　前記「フッ素樹脂製ガスケットに含まれる各不揮発成分の真密度から求められるフッ素樹脂製ガスケットの密度」は、具体的には、フッ素樹脂製ガスケットに含まれている各不揮発成分の真密度とフッ素樹脂製ガスケットにおける当該各不揮発成分の含有率とに基づき、式：
［フッ素樹脂製ガスケットに含まれる各不揮発成分の真密度から求められるフッ素樹脂製ガスケットの密度］＝Σ（Ｄｍ×Ｃｍ）／１００
〔式中、Ｄｍはフッ素樹脂製ガスケットを構成している特定不揮発成分の真密度、Ｃｍはフッ素樹脂製ガスケットを構成している全不揮発成分における特定不揮発成分の含有率（質量％）を示す〕
で表される式によって求められる値を意味する。前記特定不揮発成分の真密度は、例えば、ポリテトラフルオロエチレン（ＰＴＦＥ）では２．２ｇ／ｃｍ3であり、微粉末クレーでは２．６ｇ／ｃｍ3であり、炭化ケイ素では３．２ｇ／ｃｍ３である。 The above-mentioned "density of the fluororesin gasket obtained from the true density of each nonvolatile component contained in the fluororesin gasket" is, specifically, the true density of each nonvolatile component contained in the fluororesin gasket and the fluororesin The formula:
[Density of fluororesin gasket obtained from the true density of each non-volatile component contained in the fluororesin gasket] = Σ (Dm × Cm)/100
[In the formula, Dm is the true density of the specific non-volatile component constituting the fluororesin gasket, and Cm is the content (% by mass) of the specific non-volatile component in all the non-volatile components constituting the fluororesin gasket]
Means the value obtained by the formula represented by The true density of the specific non-volatile component is, for example, 2.2 g/cm 3 for polytetrafluoroethylene (PTFE), 2.6 g/cm 3 for fine powder clay, and 3.2 g/cm 3 for silicon carbide. is.
　フッ素樹脂製ガスケットの緻密度は、理想的にはフッ素樹脂製ガスケットに含まれる各不揮発成分の真密度から求められるフッ素樹脂製ガスケットの密度と同一である。しかし、実際にはフッ素樹脂製ガスケットに含まれている各不揮発成分間に不可避的に間隙が存在していたり、加工助剤などの不揮発成分がフッ素樹脂製ガスケットに含まれていたりすることから、フッ素樹脂製ガスケットの緻密度は、通常、フッ素樹脂製ガスケットに含まれる各不揮発成分の真密度から求められるフッ素樹脂製ガスケットの密度よりも小さい値となる。フッ素樹脂製ガスケットの緻密度は、プレフォームの圧縮倍率および圧縮回数によって変化し、プレフォームの圧縮倍率が高くなり、圧縮回数が増加するにしたがって高くなる傾向がある。 The denseness of the fluororesin gasket is ideally the same as the density of the fluororesin gasket obtained from the true density of each non-volatile component contained in the fluororesin gasket. However, in reality, there are inevitably gaps between the non-volatile components contained in fluororesin gaskets, and non-volatile components such as processing aids are contained in fluororesin gaskets. The denseness of the fluororesin gasket is usually a smaller value than the density of the fluororesin gasket obtained from the true density of each non-volatile component contained in the fluororesin gasket. The denseness of the fluororesin gasket changes depending on the compression ratio and the number of compressions of the preform, and tends to increase as the compression ratio of the preform increases and the number of compressions increases.
　フッ素樹脂製ガスケットの密度は、当該フッ素樹脂製ガスケットの質量および体積を測定することにより、求めることができる。フッ素樹脂製ガスケットに含まれている各不揮発成分の真密度から求められるフッ素樹脂製ガスケットの密度は、フッ素樹脂製ガスケットから各不揮発成分を分離し、各不揮発成分の真密度およびフッ素樹脂製ガスケットにおける各不揮発成分の含有率を測定することにより、求めることができる。 The density of a fluororesin gasket can be obtained by measuring the mass and volume of the fluororesin gasket. The density of a fluororesin gasket obtained from the true density of each non-volatile component contained in the fluororesin gasket can be obtained by separating each non-volatile component from the fluororesin gasket, determining the true density of each non-volatile component It can be determined by measuring the content of each non-volatile component.
　フッ素樹脂製ガスケットの緻密度は、ガスケットの厚さが０．８ｍｍ以下でありながらガスケットとフランジとの間で高い気密性（シール性）を確保することができるフッ素樹脂製ガスケットを得る観点から、０．９２０以上である。フッ素樹脂製ガスケットの緻密度の上限値は、特に限定されないが、高いほど好ましい。 From the viewpoint of obtaining a fluororesin gasket that can ensure high airtightness (sealing property) between the gasket and the flange while the thickness of the gasket is 0.8 mm or less, the denseness of the fluororesin gasket is: 0.920 or more. Although the upper limit of the denseness of the fluororesin gasket is not particularly limited, the higher the density, the better.
　前記で得られたフッ素樹脂製ガスケットは、必要により、常温で放置するか、あるいは適宜加熱することにより、積層シートに含まれている加工助剤などを揮散除去させてもよい。 If necessary, the fluororesin gasket obtained above may be left at room temperature or heated as appropriate to volatilize and remove the processing aid contained in the laminated sheet.
　また、フッ素樹脂製ガスケットは、フッ素樹脂の融点以上の温度で加熱することによって焼成することができる。加熱温度は、フッ素樹脂の種類によって異なるので一概には決定することができないが、フッ素樹脂製ガスケットを均一に焼成する観点およびフッ素樹脂の分解を回避する観点から、通常、３４０～３７０℃程度であることが好ましい。 In addition, the fluororesin gasket can be baked by heating at a temperature higher than the melting point of the fluororesin. The heating temperature varies depending on the type of fluororesin and cannot be determined unconditionally, but from the viewpoint of uniformly baking the fluororesin gasket and avoiding decomposition of the fluororesin, it is usually about 340 to 370°C. Preferably.
　本発明のフッ素樹脂製ガスケットは、そのままの状態で用いてもよく、あるいは所望の形状および大きさに裁断した後に用いてもよい。 The fluororesin gasket of the present invention may be used as it is, or may be used after being cut into a desired shape and size.
　なお、本発明のフッ素樹脂製ガスケットの厚さは、当該フッ素樹脂製ガスケットの用途などによって異なるが、本発明のフッ素樹脂製ガスケットの厚さが薄くても高い気密性（シール性）を確保することができるという性質を十分に発揮させる観点から、０．８ｍｍ以下であることが好ましい。 The thickness of the fluororesin gasket of the present invention varies depending on the application of the fluororesin gasket, but high airtightness (sealing property) is ensured even if the thickness of the fluororesin gasket of the present invention is thin. It is preferably 0.8 mm or less from the viewpoint of sufficiently exhibiting the property of being able to
　以上説明したように本発明のフッ素樹脂製ガスケットは、その厚さが０．８ｍｍ以下であるにもかかわらず、高い気密性（シール性）を確保することができることから、例えば、ポンプ、バルブなどの機器において、厚さが薄いガスケットが必要とされる用途に好適に使用することができる。 As described above, the fluororesin gasket of the present invention can ensure high airtightness (sealing property) in spite of its thickness being 0.8 mm or less. In equipment, it can be suitably used for applications where a gasket with a small thickness is required.
　次に本発明を実施例に基づいてさらに詳細に説明するが、本発明はかかる実施例のみに限定されるものではない。 Next, the present invention will be described in more detail based on examples, but the present invention is not limited only to such examples.
実施例１～７および比較例１～３
　ポリテトラフルオロエチレン（ＰＴＦＥ）ファインパウダー〔ダイキン工業（株）製、品番：Ｆ１０４〕１０００ｇ、充填材として微粉末のクレー〔昭和ＫＤＥ（株）製、品番：ＮＫ－３００〕１４５０ｇ（実施例１～６および比較例１～３で使用）または炭化ケイ素［昭和電工（株）製、品番：＃１２００］１４５０ｇ（実施例７で使用）、加工助剤〔エクソンモービル社製、商品名：アイソパーＣ〕１２５ｇおよび加工助剤〔エクソンモービル社製、商品名：アイソパーＧ〕１２５ｇをニーダーで５分間混合した後、得られた混合物をダイの開口部の大きさが３００ｍｍ×２０ｍｍの長方形である押出機で押し出すことにより、表１に示す厚さを有するプレフォームを作製した。 Examples 1-7 and Comparative Examples 1-3
Polytetrafluoroethylene (PTFE) fine powder [manufactured by Daikin Industries, Ltd., product number: F104] 1000 g, fine powder clay as a filler [manufactured by Showa KDE Co., Ltd., product number: NK-300] 1450 g (Example 1- 6 and Comparative Examples 1 to 3) or silicon carbide [manufactured by Showa Denko K.K., product number: #1200] 1450 g (used in Example 7), processing aid [manufactured by ExxonMobil, product name: Isopar C] After mixing 125 g and 125 g of a processing aid [manufactured by ExxonMobil, trade name: Isopar G] in a kneader for 5 minutes, the resulting mixture was extruded in an extruder having a rectangular die opening size of 300 mm x 20 mm. Preforms having the thicknesses shown in Table 1 were made by extrusion.
　次に、圧延ロールとして二軸ロール（ロールの直径：７００ｍｍ、初期のロール間の間隔：２０ｍｍ、ロールの表面温度：６０℃）を用い、前記で得られたプレフォームを走行速度６ｍ／ｍｉｎで当該二軸ロールのロール間に通過させ、引き続いて二軸ロールのロール間の間隔が徐々に狭められた二軸ロールのロール間に順次通過させて圧延し、最後に表１に示すフッ素樹脂製ガスケットの厚さに対応する間隔を有する二軸ロールのロール間に通過させて圧延することにより、フッ素樹脂製ガスケットを得た。プレフォームを二軸ロールのロール間に通過させて圧延させる回数（圧延回数）およびプレフォームの圧縮倍率は、表１に記載の製造条件の欄に示すとおりである。 Next, using biaxial rolls (roll diameter: 700 mm, initial gap between rolls: 20 mm, roll surface temperature: 60°C) as rolling rolls, the preform obtained above was run at a running speed of 6 m/min. It is passed between the rolls of the biaxial rolls, successively passed between the rolls of the biaxial rolls in which the gap between the rolls of the biaxial rolls is gradually narrowed, and rolled, and finally the fluororesin shown in Table 1. A fluororesin gasket was obtained by passing between rolls of biaxial rolls having a gap corresponding to the thickness of the gasket and rolling. The number of times the preform is rolled by passing it between the rolls of the biaxial rolls (the number of rolling times) and the compression ratio of the preform are as shown in the manufacturing conditions column in Table 1.
　前記で得られたフッ素樹脂製ガスケットの厚さ、表面粗さおよび緻密度を表１に記載のガスケットの性能の欄に示す。 The thickness, surface roughness and denseness of the fluororesin gasket obtained above are shown in the gasket performance column in Table 1.
　次に、前記で得られたフッ素樹脂製ガスケットの気密性（シール性）を以下の方法に基づいて調べた。その結果を表１に記載のガスケットの性能の欄に示す。 Next, the airtightness (sealing property) of the fluororesin gasket obtained above was examined based on the following method. The results are shown in the gasket performance column in Table 1.
〔気密性（シール性）の測定方法〕
　ＪＩＳ　Ｂ２４９０（２００８）の「管フランジ用ガスケットの密封特性試験方法」の付属書Ｃに準じて気密性（シール性）を調べた。なお、試料として内径４８ｍｍ、外形６７ｍｍの寸法に打ち抜いたガスケットを用い、当該ガスケットを直径が１００ｍｍ、高さが５０ｍｍ、表面粗さＲｚが３μｍである鋼フランジ間に装着し、圧縮試験機により面圧が１９．６ＭＰａとなるよう荷重を負荷した。フランジに設けられた圧力導入用の貫通孔からガスケットの内径側に窒素ガスで０．９８ＭＰａの圧力を付与し、５分間放置した後、石鹸膜流量計を用いて当該窒素ガスの漏れ量を求めた。 [Method for measuring airtightness (sealing property)]
The airtightness (sealing property) was examined according to Appendix C of JIS B2490 (2008) "Methods for testing sealing characteristics of gaskets for pipe flanges". As a sample, a gasket with an inner diameter of 48 mm and an outer diameter of 67 mm was used. A load was applied so that the pressure was 19.6 MPa. Apply a pressure of 0.98 MPa with nitrogen gas to the inner diameter side of the gasket from the through hole for introducing pressure provided in the flange, leave it for 5 minutes, and then determine the leakage amount of the nitrogen gas using a soap film flow meter. rice field.
　前記漏れ量が３．０×１０-4Ｐａ・ｍ3／ｓｅｃ以下であるとき、ガスケットは、気密性（シール性）の合格基準を満たす。 When the leak rate is 3.0×10 −4 Pa·m 3 /sec or less, the gasket satisfies the airtightness (sealing property) acceptance criteria.
Figure JPOXMLDOC01-appb-T000001
  
Figure JPOXMLDOC01-appb-T000001
  
　表１に示された結果から、各実施例で得られたフッ素樹脂製ガスケットは、いずれも充填材の種類に関係なく、当該フッ素樹脂製ガスケットの厚さが０．８ｍｍ以下であるにもかかわらず、表面粗さＲａが２．１μｍ以下であり、緻密度が０．９２０以上であることから、気密性（シール性）に優れていることがわかる。

  From the results shown in Table 1, it can be seen that the fluororesin gaskets obtained in each example have a thickness of 0.8 mm or less regardless of the type of filler. However, since the surface roughness Ra is 2.1 μm or less and the density is 0.920 or more, it can be seen that the airtightness (sealing property) is excellent.

Claims (3)

  1. 　フッ素樹脂および充填材を含有し、厚さが０．８ｍｍ以下であるフッ素樹脂製ガスケットであって、表面粗さＲａが２．１μｍ以下であり、緻密度が０．９２０以上であることを特徴とするフッ素樹脂製ガスケット。 A fluororesin gasket containing a fluororesin and a filler, having a thickness of 0.8 mm or less, and having a surface roughness Ra of 2.1 μm or less and a density of 0.920 or more. Fluorine resin gasket.
  2. 　請求項１に記載のフッ素樹脂製ガスケットを製造する方法であって、フッ素樹脂および充填材を含有し、厚さが２０～２００ｍｍであるプレフォームを用い、厚さが０．８ｍｍ以下、表面粗さＲａが２．１μｍ以下、緻密度が０．９２０以上となるまで当該プレフォームの圧延を繰り返すことを特徴とするフッ素樹脂製ガスケットの製造方法。 A method for manufacturing a fluororesin gasket according to claim 1, wherein a preform containing a fluororesin and a filler and having a thickness of 20 to 200 mm is used, the thickness is 0.8 mm or less, and the surface roughness is A method for producing a fluororesin gasket, characterized in that rolling of the preform is repeated until the thickness Ra is 2.1 μm or less and the compactness is 0.920 or more.
  3. 　プレフォームを圧延するときの圧延ロールの表面温度が４０～８０℃である請求項２に記載のフッ素樹脂製ガスケットの製造方法。 The method for producing a fluororesin gasket according to claim 2, wherein the surface temperature of the rolling rolls when rolling the preform is 40 to 80°C.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008007607A (en) * 2006-06-28 2008-01-17 Nippon Valqua Ind Ltd Filler-filled fluororesin sheet and process for producing filler-filled fluororesin sheet
JP2011153254A (en) * 2010-01-28 2011-08-11 Nippon Valqua Ind Ltd Sheet forming composition, filler-containing fluororesin sheet, and method for producing the filler-containing fluororesin sheet
JP2020524096A (en) * 2017-06-15 2020-08-13 ダブリュ．エル．ゴア アンド アソシエイツ，インコーポレイティドＷ．Ｌ． Ｇｏｒｅ ＆ Ａｓｓｏｃｉａｔｅｓ， Ｉｎｃｏｒｐｏｒａｔｅｄ Supported elastomer foam and method of making supported elastomer foam
WO2021210435A1 (en) * 2020-04-15 2021-10-21 株式会社バルカー Sealing material

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008007607A (en) * 2006-06-28 2008-01-17 Nippon Valqua Ind Ltd Filler-filled fluororesin sheet and process for producing filler-filled fluororesin sheet
JP2011153254A (en) * 2010-01-28 2011-08-11 Nippon Valqua Ind Ltd Sheet forming composition, filler-containing fluororesin sheet, and method for producing the filler-containing fluororesin sheet
JP2020524096A (en) * 2017-06-15 2020-08-13 ダブリュ．エル．ゴア アンド アソシエイツ，インコーポレイティドＷ．Ｌ． Ｇｏｒｅ ＆ Ａｓｓｏｃｉａｔｅｓ， Ｉｎｃｏｒｐｏｒａｔｅｄ Supported elastomer foam and method of making supported elastomer foam
WO2021210435A1 (en) * 2020-04-15 2021-10-21 株式会社バルカー Sealing material

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