CN115349004A - Sealing material - Google Patents

Sealing material Download PDF

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Publication number
CN115349004A
CN115349004A CN202180025002.4A CN202180025002A CN115349004A CN 115349004 A CN115349004 A CN 115349004A CN 202180025002 A CN202180025002 A CN 202180025002A CN 115349004 A CN115349004 A CN 115349004A
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China
Prior art keywords
sealing material
fluororesin
inorganic filler
average particle
sheet
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CN202180025002.4A
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Chinese (zh)
Inventor
中出贤志郎
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Walka Corp
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Walka Corp
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
    • C09K3/1006—Materials in mouldable or extrudable form for sealing or packing joints or covers characterised by the chemical nature of one of its constituents
    • C09K3/1009—Fluorinated polymers, e.g. PTFE
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
    • C08K3/013—Fillers, pigments or reinforcing additives
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
    • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
    • 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

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Sealing Material Composition (AREA)
  • Gasket Seals (AREA)

Abstract

One embodiment of the present invention provides a sealing material having improved sealing properties while maintaining creep resistance required for the sealing material, the sealing material comprising a fluororesin having a crystallinity of 50% or more and an inorganic filler.

Description

Sealing material
Technical Field
One embodiment of the present invention relates to a sealing material.
Background
A fluororesin sheet filled with a filler is a sheet obtained by processing a mixture of a fluororesin and a filler into a sheet, and is widely used for sealing materials and the like by adding, in addition to the properties such as chemical resistance and heat resistance of the fluororesin, the inherent functions and properties of the filler or by improving the creep resistance which is a defect of the fluororesin.
As such a fluororesin sheet filled with a filler, for example, a fluororesin sheet filled with a filler containing a fluororesin and an inorganic filler having a modified mohs hardness of 8 or more described in patent document 1 is known.
Documents of the prior art
Patent literature
Patent document 1: japanese patent laid-open publication No. 2010-235755
Disclosure of Invention
Technical problem to be solved by the invention
Since the above-mentioned conventional filler-filled fluororesin sheet tends to have a reduced creep resistance (is susceptible to stress relaxation) if the sealing properties thereof are to be improved, and a reduced sealing properties if the creep resistance thereof is to be improved (is inhibited from stress relaxation), the sealing properties and the creep resistance have a trade-off relationship, and the other property is sacrificed when the sealing properties and the creep resistance are to be improved.
For example, if the amount of the fluororesin is increased to improve the sealing property of the conventional fluororesin sheet filled with a filler as described in patent document 1 and the like, the creep resistance is decreased, and there is a limit to improve the sealing property while maintaining the creep resistance required for the sealing material.
One embodiment of the present invention provides a sealing material having improved sealing properties while maintaining the creep resistance required for the sealing material.
Means for solving the problems
The present inventors have conducted extensive studies to solve the above-described problems, and as a result, have found that the above-described problems can be solved by the following configuration examples, thereby completing the present invention.
The constitution of the present invention is as follows.
[1] A sealing material comprising a fluororesin and an inorganic filler, the fluororesin having a crystallinity of 50% or more.
[2] The sealing material according to [1], wherein the ratio of the total volume of the fluororesin to the total volume of the inorganic filler (volume of fluororesin/volume of inorganic filler) is 40/60 to 70/30.
[3] The sealing material according to [1] or [2], wherein the inorganic filler has an average particle diameter of 1 to 30 μm.
[4] The sealing material according to any one of [1] to [3], wherein the inorganic filler contains 2 or more types of particles having different average particle diameters.
[5] The sealing material according to any one of [1] to [4], wherein the sealing material is a gasket.
ADVANTAGEOUS EFFECTS OF INVENTION
According to one embodiment of the present invention, a sealing material having improved sealing properties compared to a conventional fluororesin sheet filled with a filler can be provided while maintaining creep resistance required for a sealing material of the same degree as the creep resistance of the conventional fluororesin sheet filled with a filler.
Further, according to one embodiment of the present invention, a sealing material which is not easily deformed and has high tensile strength can be easily obtained.
Detailed Description
Sealing Material
A sealing material according to an embodiment of the present invention (hereinafter also referred to as "the present sealing material") includes an inorganic filler and a fluororesin having a crystallinity of 50% or more.
The sealing material exhibits the above-described effects, and therefore, is suitably used as a gasket, particularly a gasket for a pipe (e.g., a pipe flange) or a valve, a sealing material for a valve opening/closing member, a gasket for a lid of a container, a tank, or the like, a gasket for a meter, an observation window, or the like attached to a container, a tank, or the like.
The shape and size of the sealing material are not particularly limited, and may be selected according to the intended use.
< fluororesin >
The fluororesin is not particularly limited as long as it is a fluororesin having a crystallinity of 50% or more (hereinafter also referred to as "fluororesin a").
The fluororesin a contained in the present sealing material may be 1 kind or 2 or more kinds. The present sealing material may contain 1 or 2 or more kinds of fluororesins a, and may further contain a fluororesin b having a crystallinity of less than 50%. The content of the fluororesin a relative to the total amount of the fluororesin included in the present sealing material is preferably 30 to 100 mass%.
The crystallinity of the fluororesin a is 50% or more, preferably 55% or more, more preferably 60% or more, from the viewpoint of easily obtaining a sealing material or the like which has improved sealing properties while maintaining creep resistance, and the upper limit thereof is preferably 80% or less from the viewpoint of easily obtaining a sealing material or the like which has high tensile strength and is less likely to be crushed.
The crystallinity of the fluororesin included in the conventional filling material-filled fluororesin sheet is generally about 45%, and the crystallinity of the fluororesin a is significantly higher than that of the fluororesin included in the conventional filling material-filled fluororesin sheet.
The crystallinity of the fluororesin of the present invention is the crystallinity of the fluororesin contained in the sealing material, and is not the crystallinity of the fluororesin used as a raw material for producing the sealing material. That is, the present sealing material may contain a fluororesin having a crystallinity within the above range, and the crystallinity of the fluororesin used as a raw material for producing the sealing material may be within the above range or outside the above range.
The crystallinity of the fluororesin in the present specification can be measured specifically by the method described in the following examples.
Examples of the fluororesin include Polytetrafluoroethylene (PTFE), modified PTFE, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (EPE), vinyl fluoride-vinyl ether copolymer (FEVE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and ethylene-chlorotrifluoroethylene copolymer (ECTFE).
Among these, PTFE or modified PTFE is preferred from the viewpoint of being able to more easily obtain the present sealing material containing a fluororesin having a crystallinity within the above range, moldability, processability, and the like.
The fluororesin used as a raw material for producing the present sealing material may be in the form of a powder or a dispersion of fluororesin powder. When a dispersion of a fluororesin powder is used as a raw material for producing the sealing material, there is an advantage that the inorganic filler can be uniformly dispersed.
The content of the fluororesin a in the present sealing material is preferably 8 to 82% by mass, more preferably 15 to 82% by mass, from the viewpoint of further enabling the characteristics of the fluororesin to be exhibited and facilitating the production of a sealing material having improved sealing properties while maintaining creep resistance.
< inorganic Filler Material >
The inorganic filler is not particularly limited, and conventionally known inorganic fillers can be used.
The number of the inorganic sealing materials contained in the sealing material may be 1 or 2 or more. When the sealing material contains 2 or more kinds of inorganic fillers, 2 or more kinds of inorganic fillers having different kinds (materials) may be used, or 2 or more kinds of inorganic fillers having different average particle diameters or shapes may be used.
Examples of the inorganic filler include carbon fillers such as graphite, carbon black, expanded graphite, activated carbon, carbon nanotubes, diamond, and carbon fibers, oxide fillers such as magnesia, silica, alumina, and (fused) zirconia, nitride fillers such as boron nitride and silicon nitride, carbide fillers such as boron carbide, silicon carbide, tungsten carbide, and tantalum carbide, carbonate fillers such as calcium carbonate, sulfate fillers such as barium sulfate and calcium sulfate, and mineral fillers such as talc, mica, clay, garnet, topaz, and rock wool.
Among them, carbon black, silica, alumina, silicon carbide, barium sulfate, and clay are preferable, and silica, alumina, silicon carbide, barium sulfate, and clay are more preferable, from the viewpoint of easily obtaining a sealing material that is not easily deformed (hardly deformed) even in a high-temperature state.
The shape of the inorganic filler is not particularly limited, and may be any shape such as a particle shape (including a flake shape) and a fiber shape, and is preferably a particle shape.
When the inorganic filler is in the form of particles, the average particle diameter thereof is preferably 1 to 30 μm, more preferably 1 to 20 μm, and still more preferably 1 to 15 μm, from the viewpoint of easy availability of a sealing material having a low compressibility even at high temperatures.
In the present specification, the "average particle diameter" is a particle diameter (median diameter) at which the cumulative number in the particle size distribution measured by the laser refraction and scattering method reaches 50%. The particle size distribution can be prepared, for example, by using a dynamic light scattering particle size distribution measuring device (horiba manufactured by horiba corporation), commercial product number: LB-550.
The present sealing material preferably contains 2 or more kinds of inorganic fillers (particles) having different average particle diameters, from the viewpoint of easily obtaining a sealing material having improved sealing properties while maintaining creep resistance and having a low compressibility even at high temperatures.
As described above, when the present sealing material contains 2 or more kinds of inorganic fillers (particles) having different average particle diameters, it is preferable to contain the inorganic filler a having an average particle diameter in the range of 7 to 30 μm and the inorganic filler B having an average particle diameter in the range of 1 to 5 μm, from the viewpoint of easy availability of a sealing material having a low compressibility even at high temperatures.
The average particle diameter of the inorganic filler A is more preferably 7 to 20 μm, and the average particle diameter of the inorganic filler B is more preferably 2 to 5 μm.
When the present sealing material contains the inorganic fillers a and B, the volume ratio (inorganic filler a/inorganic filler B) is preferably 45/55 to 80/20, more preferably 50/50 to 75/25, from the viewpoint of easy availability of a sealing material having a low compressibility even at high temperatures.
The ratio of the total volume of the fluororesin, particularly the fluororesin a, to the total volume of the inorganic filler (volume of the fluororesin/volume of the inorganic filler) in the present sealing material is preferably 40/60 to 70/30, more preferably 40/60 to 60/40, and still more preferably 45/55 to 55/45, from the viewpoint of easily obtaining a sealing material having excellent sealing properties and a low compressibility even at high temperatures.
If the content of the fluororesin is less than the above range, the sealing property tends to be lowered, and if the content of the fluororesin is more than the above range, the creep resistance tends to be lowered.
< other ingredients >
The present sealing material may be a sealing material composed of only the fluororesin and the inorganic filler, or may further contain other conventionally known components usable for sealing materials other than the fluororesin and the inorganic filler within a range not affecting the object of the present invention.
Examples of the other component include a tackiness imparting agent such as terpene resin, terpene-phenol resin, coumarone-indene resin, rosin, an ultraviolet absorber, an antioxidant, a polymerization inhibitor, a coloring agent such as a pigment, a powder of a resin such as PPS, and an organic fiber such as an aramid fiber.
These other components may be used in 1 kind or more than 2 kinds.
< method for producing the sealing material >
The sealing material can be produced, for example, by molding a resin composition containing a fluororesin, an inorganic filler, and if necessary, a processing aid or the other components into a sheet form.
The fluororesin used in the resin composition may be in the form of a powder or a dispersion liquid obtained by dispersing a fluororesin powder in a dispersion medium. When the dispersion of the fluororesin powder is used, the inorganic filler can be uniformly dispersed.
The amount of the fluororesin and the inorganic filler in the resin composition may be such that the amount of the fluororesin and the inorganic filler in the obtained sealing material falls within the above range.
The processing aid is not particularly limited, and examples thereof include petroleum-based carbon solvents such as paraffin-based hydrocarbon solvents.
The petroleum hydrocarbon solvent may be a commercially available solvent, and examples thereof include Isopar C, isopar E, isopar G, isopar H, isopar L and Isopar M [ trade names of the above products, manufactured by Exxon Mobil).
The content of the processing aid in the resin composition may be appropriately selected depending on the kind of the sealing material, and is not always determined, but is preferably about 5 to 35% by mass.
The resin composition can be prepared by mixing a fluororesin, an inorganic filler, a processing aid used as needed, the other components, and the like in an arbitrary order, all at once or a small number of times so as to have a uniform composition. In order to obtain a resin composition having a uniform composition, a processing aid may be added to the resin composition in an excess amount, and after sufficiently stirring, the excess processing aid may be removed by means of, for example, filtration, volatilization, or the like.
The method for molding the resin composition into a sheet shape is not particularly limited, but the resin composition is preferably produced by sequentially preforming, rolling, (drying if necessary), and firing the resin composition.
The preforming may be performed, for example, by extrusion-molding the resin composition. By this extrusion molding, a preform (extrusion molded article) can be obtained. The preform is not particularly limited in shape, but is preferably rod-shaped or tape-shaped in consideration of efficiency of sheet formation thereafter, sheet-shaped homogeneity, and the like.
The calendering preferably calenders the resulting preform. The preform may be rolled by, for example, passing the preform between two rolling rolls such as biaxial rolls to roll the preform into a sheet. The rolled sheet obtained by rolling the preform may be further repeatedly rolled a plurality of times. By repeating the rolling, the inside of the rolled sheet can be further densified. In the case of repeating the rolling with the biaxial rolls, it is preferable to gradually narrow the roll interval of the reduction rolls for each repetition of the rolling.
When a rolled sheet is produced by rolling a preform with a biaxial roller, a method of rolling the preform with the distance between the rolling rollers adjusted to 0.5 to 20mm and the moving speed of the surface of the rolling rollers (sheet extrusion speed) set to 5 to 50 mm/sec may be mentioned.
When the processing aid remains in the rolled sheet obtained as described above, the processing aid may be removed by leaving the rolled sheet at room temperature or heating the rolled sheet at a temperature lower than the melting point of the fluororesin, if necessary.
Next, the rolled sheet obtained above was fired. As a method for firing the rolled sheet, for example, a method of heating the rolled sheet to a temperature equal to or higher than the melting point of the fluororesin and firing the same may be mentioned. The heating temperature varies depending on the type of the fluororesin, but is preferably about 340 to 370 ℃ from the viewpoint of uniformly baking the whole rolled sheet and suppressing the generation of fluorine-based gas at high temperature.
The sheet after firing is usually used after being cooled to about room temperature, and by cooling at a cooling rate of preferably 1.0 ℃/min or less, more preferably 0.85 ℃/min or less, and still more preferably 0.7 ℃/min or less by slow cooling at that time, a sealing material comprising a fluororesin having a crystallinity within the above-mentioned range can be easily obtained.
The cooling rate is preferably 0.1 ℃/min or more, in view of easy availability of a sealing material having high tensile strength.
The sheet produced as described above can be used as a gasket as it is, or can be used as a sealing material after being cut into a desired shape.
Examples
The present invention will be described in further detail below with reference to examples, but the present invention is not limited to the examples.
[ example 1]
Fluororesin powder [ product of AGC co., ltd., polytetrafluoroethylene powder, product number: CD-1, density: 2200kg/m 3 1000g, silicon carbide particles [ hydrochloric acid (hydrochloric acid), producing (hydrochloric acid) into particles (hydrochloric acid), commercial numbers: #1200, average particle diameter: 1400g of 9.5 μm, auxiliary A (trade name: isopar C, fraction temperature: 97 to 104 ℃ C. ], 125G of an auxiliary B (product name: isopar G, cut fraction temperature: 158 to 175 ℃ C., manufactured by Exxon Mobil Co., ltd.) and 125G of an auxiliary B were mixed in a kneader for 5 minutes, and then the mixture was left to stand at room temperature (25 ℃ C.) for 16 hours to be cured to obtain a composition for forming a sheet。
The sheet-forming composition obtained above was extruded at room temperature (25 ℃ C.) using a die 300 mm. Times.20 mm extruder to obtain a preform. The preform obtained above was rolled with a biaxial roller under the conditions of a roller diameter of 700mm, a roller interval of 20mm, a roller speed of 6m/min and a roller temperature of 40 ℃. The rolled sheet was subjected to further rolling with biaxial rolls having a roll interval of 10mm, then the further rolled sheet was subjected to further rolling with biaxial rolls having a roll interval of 5mm, and finally the above-rolled sheet was subjected to further rolling with biaxial rolls having a roll interval of 1.5mm, thereby obtaining a rolled sheet having a thickness of 1.5 mm.
The rolled sheet obtained above was left to stand at room temperature (25 ℃) for 24 hours, after removing the auxiliary agent, was fired at 350 ℃ for 3 hours in an electric furnace, and then slowly cooled at a cooling rate of 0.7 ℃/min, thereby obtaining a sealing material. The volume ratio of the fluororesin and the inorganic filler in the sealing material (fluororesin/inorganic filler) was 51/49.
[ example 2]
In the same manner as in example 1, a rolled sheet was obtained, and the obtained rolled sheet was left at room temperature (25 ℃) for 24 hours, after removing the auxiliary agent, it was fired at 350 ℃ for 3 hours in an electric furnace, and then gradually cooled at a cooling rate of 0.5 ℃/minute, thereby obtaining a sealing material.
[ example 3]
A rolled sheet was obtained in the same manner as in example 1, and the obtained rolled sheet was left at room temperature (25 ℃) for 24 hours, after removing the auxiliary agent, fired at 350 ℃ for 3 hours in an electric furnace, and then gradually cooled at a cooling rate of 0.25 ℃/min to obtain a sealing material.
[ example 4]
A rolled sheet was obtained in the same manner as in example 1, and the obtained rolled sheet was left at room temperature (25 ℃) for 24 hours, after removing the auxiliary agent, fired at 350 ℃ for 3 hours in an electric furnace, and then gradually cooled at a cooling rate of 0.1 ℃/minute, to obtain a sealing material.
[ example 5]
A sealing material was produced in the same manner as in example 2, except that CD-1 and silicon carbide particles were used so that the volume ratio of the fluororesin to the inorganic filler (fluororesin/inorganic filler) was 40/60.
[ example 6]
A sealing material was produced in the same manner as in example 2, except that CD-1 and silicon carbide particles were used so that the volume ratio of the fluororesin to the inorganic filler (fluororesin/inorganic filler) was 60/40 or more.
[ example 7]
Except that silicon carbide particles [ product number, product name, manufactured by concentrated electric smelting: #4000, average particle diameter: a sealing material was obtained in the same manner as in example 2 except that the thickness was changed to 3 μm.
[ example 8]
Except that silicon carbide particles [ product number, product name, manufactured by concentrated electric smelting: #8000, average particle diameter: a sealing material was obtained in the same manner as in example 2 except for 14 μm.
[ example 9]
Except that silicon carbide particles [ product number, product name, manufactured by concentrated electric smelting: #7000, average particle diameter: a sealing material was obtained in the same manner as in example 2 except for the thickness of 17 μm.
[ example 10]
Except that silicon carbide particles (product number of shinny electric smelting corporation: #5000, average particle diameter: a sealing material was obtained in the same manner as in example 2 except for the thickness of 25 μm.
[ example 11]
Except that silica (manufactured by deyama corporation (ltd.) \\1246312510: a sealing material was obtained in the same manner as in example 2 except for the thickness of 10 μm.
[ example 12]
Except that α -alumina (made by showa electrical corporation) was used as the inorganic filler, a-420, average particle diameter: a sealing material was obtained in the same manner as in example 2 except that the thickness was changed to 3.9. Mu.m.
[ example 13]
Except that clay (manufactured by showa KDE corporation, NK300, average particle diameter: a sealing material was obtained in the same manner as in example 2 except that the thickness was changed to 9.5. Mu.m.
[ example 14]
Except that barium sulfate (produced by Zhuyuan chemical industry Co., ltd., W-10, average particle diameter: a sealing material was obtained in the same manner as in example 2 except for the difference of 10 μm.
[ example 15]
Except that silicon carbide particles [ product number, product name, manufactured by concentrated electric smelting: #4000, average particle diameter: 3 μm, 350g, and silicon carbide particles (product of shinny electric smelting Co., ltd., trade name: #1200, average particle diameter: a sealing material was obtained in the same manner as in example 2 except for 9.5 μm 1050 g.
[ example 16]
Except that silicon carbide particles [ product number, product name, manufactured by concentrated electric smelting: #4000, average particle diameter: 3 μm, and silicon carbide particles [ product number of Funiu electric smelting Co., ltd.: #1200, average particle diameter: a sealing material was prepared in the same manner as in example 2 except that 700g of 9.5. Mu.m.was used.
Comparative example 1
In the same manner as in example 1, a rolled sheet was obtained, and the obtained rolled sheet was left at room temperature (25 ℃) for 24 hours, after removing the auxiliary agent, fired at 350 ℃ for 3 hours in an electric furnace, followed by air cooling, to obtain a sealing material.
Comparative example 2
A sealing material was produced in the same manner as in comparative example 1, except that CD-1 and silicon carbide particles were used so that the volume ratio of the fluororesin to the inorganic filler (fluororesin/inorganic filler) was 39/61.
Comparative example 3
A sealing material was produced in the same manner as in comparative example 1, except that CD-1 and silicon carbide particles were used so that the volume ratio of the fluororesin to the inorganic filler (fluororesin/inorganic filler) was 73/27.
< crystallinity of fluororesin in sealing Material >
The crystallinity of the fluororesin in the sealing material obtained above was measured as follows. The results are shown in Table 1.
DSC6200 manufactured by a precision instruments (124751245212467\\1254012512512584 \ (12412523), was used as a device, and the heat of fusion (Δ H) calculated from the peak area of the endothermic peak observed at the 1 st temperature rise curve at this time was measured at a temperature rise rate of 5 ℃/min from 30 ℃.
Crystallinity (%) =Δh × 100/(Δhb × w)
[ Here,. DELTA.Hb represents the calorific value of the fluororesin in terms of melting, and w represents the content (mass%) of the fluororesin in the sealing material. ]
The heat of fusion value Δ Hb of the fluororesin as a raw material to be used can be measured in the same manner as in the method for measuring the heat of fusion of a sealing material. When the fluororesin contained in the sealing material is PTFE, a value of 54.8mJ/mg is used as Δ Hb in the present invention, and when the fluororesin contained in the sealing material is modified PTFE, a value of 50.0mJ/mg is used as Δ Hb in the present invention.
Specifically, the content w of the fluororesin in the sealing material is calculated from the weight loss amount visible in the vicinity of 420 to 645 ℃ when measured by a thermogravimetric analyzer (TG) under the following conditions.
The using device comprises the following steps: TG/DTA6200 (precision instruments manufactured by Seiko Co., ltd.)
Test temperature: 30-800 DEG C
Temperature rise rate: 10 ℃/min
Atmosphere: nitrogen gas
< sealing >
A gasket having an outer shape of 65mm and an inner shape of 50mm was obtained from the sealing material obtained above. The obtained gasket was sandwiched by a metal platen, nitrogen gas having an internal pressure of 0.98MPa was sealed under a load stress of 19.8MPa, and the nitrogen gas leaking from the gasket was collected by a sleeve, and the sealing property (leakage amount) was measured by a diaphragm flowmeter. As an evaluation, the amount of leakage was 1.7X 10 -4 Pa·m 3 Time-recorder below sO, the leakage amount exceeds 1.7X 10 -4 Pa·m 3 When the amount is/s, it is expressed as X. The results are shown in Table 1.
< creep resistance (stress relaxation Rate) >
The sealing material obtained above was prepared into a sample piece, and the stress relaxation rate was measured in accordance with JIS R3453. For the evaluation, the stress relaxation rate was rated as "o" when it was 70% or less, and rated as "x" when it exceeded 70%. The results are shown in Table 1.
< tensile Strength >
The sealing material obtained above was prepared into a sample piece, and the tensile strength was measured in accordance with JIS R3453. As the evaluation, the tensile strength was rated as "good" when it was 9.8MPa or more, as "delta" when it was 5MPa or more but less than 9.8MPa, and as "x" when it was less than 5 MPa. The results are shown in Table 1.
[ Table 1]
Figure BDA0003866202450000121

Claims (5)

1. A sealing material comprising a fluororesin and an inorganic filler, the fluororesin having a crystallinity of 50% or more.
2. The sealing material according to claim 1, wherein the ratio of the total volume of the fluororesin to the total volume of the inorganic filler, that is, the volume of the fluororesin/the volume of the inorganic filler is 40/60 to 70/30.
3. The sealing material according to claim 1 or 2, wherein the inorganic filler has an average particle diameter of 1 to 30 μm.
4. The sealing material according to any one of claims 1 to 3, wherein the inorganic filler contains 2 or more types of particles having different average particle diameters.
5. The sealing material according to any one of claims 1 to 4, wherein the sealing material is a gasket.
CN202180025002.4A 2020-04-15 2021-04-05 Sealing material Pending CN115349004A (en)

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JP2020072948 2020-04-15
JP2020-072948 2020-04-15
PCT/JP2021/014433 WO2021210435A1 (en) 2020-04-15 2021-04-05 Sealing material

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US20040173978A1 (en) * 2003-03-06 2004-09-09 Christopher Bowen PTFE membranes and gaskets made therefrom
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JP5491758B2 (en) 2009-03-31 2014-05-14 日本バルカー工業株式会社 Filled fluororesin sheet, method for producing the same, and gasket
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