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WO2024238873A1 - Composition de revêtement pour élément d'étanchéité en caoutchouc - Google Patents

Composition de revêtement pour élément d'étanchéité en caoutchouc Download PDF

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Publication number
WO2024238873A1
WO2024238873A1 PCT/US2024/029825 US2024029825W WO2024238873A1 WO 2024238873 A1 WO2024238873 A1 WO 2024238873A1 US 2024029825 W US2024029825 W US 2024029825W WO 2024238873 A1 WO2024238873 A1 WO 2024238873A1
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WO
WIPO (PCT)
Prior art keywords
sealing member
rubber sealing
coating composition
fluororesin
coating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/US2024/029825
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English (en)
Inventor
Hoai-Nam Pham
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chemours Mitsui Fluoroproducts Co Ltd
Chemours Co FC LLC
Original Assignee
Chemours Mitsui Fluoroproducts Co Ltd
Chemours Co FC LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Chemours Mitsui Fluoroproducts Co Ltd, Chemours Co FC LLC filed Critical Chemours Mitsui Fluoroproducts Co Ltd
Priority to CN202480032298.6A priority Critical patent/CN121127545A/zh
Publication of WO2024238873A1 publication Critical patent/WO2024238873A1/fr
Anticipated expiration legal-status Critical
Pending legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D127/00—Coating compositions based on 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; Coating compositions based on derivatives of such polymers
    • C09D127/02—Coating compositions based on 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; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
    • C09D127/12—Coating compositions based on 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; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C09D127/18—Homopolymers or copolymers of tetrafluoroethene
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D115/00—Coating compositions based on rubber derivatives
    • C09D115/005—Hydrogenated nitrile rubber
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/63—Additives non-macromolecular organic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F114/00—Homopolymers 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
    • C08F114/18—Monomers containing fluorine
    • C08F114/26—Tetrafluoroethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F214/00—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
    • C08F214/18—Monomers containing fluorine
    • C08F214/26—Tetrafluoroethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F214/00—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
    • C08F214/18—Monomers containing fluorine
    • C08F214/26—Tetrafluoroethene
    • C08F214/262—Tetrafluoroethene with fluorinated vinyl ethers
    • 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
    • C08K5/00—Use of organic ingredients
    • C08K5/54—Silicon-containing compounds
    • C08K5/544—Silicon-containing compounds containing nitrogen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend

Definitions

  • the present invention relates to a fluororesin coating composition that can be suitably applied to rubber sealing members, and more specifically to a fluororesin coating composition that can provide excellent tack-free properties toward metals to rubber sealing members that come in contact with metal.
  • Rubber sealing members such as gaskets, valve seals, and check valves are widely used in automobiles, industrial machinery, and otherfields.
  • Rubber sealing members may have a film containing a coating agent made of rubber components and fluororesin particles formed on a surface of the rubber sealing member to prevent tackiness to the opposing material and to enable instantaneous opening and closing of the seal.
  • Patent Document 1 discloses a coating agent for oil-seals prepared as an organic solvent solution containing a total of 10 to 90 parts by weight of fluoropolymer particles with a particle size of 2 pm or less and filler particles other than fluoropolymer particles with a particle size of 0.5 to 30 pm and 10 to 40 parts by weight of wax with a melting point of 40 to 160°C, in proportion to 100 parts by weight of 1 ,2-polybutadiene containing an isocyanate group, wherein the fluoropolymer particlesat a ratio of 20 to 80% by weight of the total amount of filler.
  • the present inventors proposed a coating composition capable of forming a coating film that can express excellent releasability over a long period of time for a substrate having inferior heat resistance such as a rubber or plastic substrate (see Patent Document 2 below).
  • This coating composition also has high coating film adhesion to the substrate, so use on rubber sealing members such as those described above is also being considered.
  • Patent Document 1 International Publication WO 2021/014901
  • Patent Document 2 Japanese Unexamined Patent Application Publication 2022-136748
  • Rubber sealing members used in contact with metal are required to have tack-free properties so that they do not stick to metal even when lightly touched, so as not to impair sealing performance (to prevent adhesion to metal members by seal rings and gaskets, and to enable instantaneous opening and closing in valve seals and valves).
  • a coating film made of the coating composition described in Patent Document 2 is excellent in terms of providing mold-releasing properties to bladders and the like, but is unable to control tack-free properties (non-tacking properties) as required for metals.
  • an object of the present invention is to provide a coating composition capable of forming a coating film with excellent durability, which can be used for a rubber sealing member that is used in contact with metal, and which can exhibit excellent adhesion to rubber substrates and tack-free properties (non-tacking properties) to a metal member that is the opposing material, over a long period of time.
  • Another object of the present invention is to provide a rubber sealing member such as a seal ring, gasket, valve seal, check valve, or the like, having a coating film with excellent tack-free (non-tacking) properties to metal members.
  • the present invention provides a coating composition for a rubber sealing member containing hydrogenated acrylonitrile butadiene rubber (hereinafter also referred to as HNBR) and a perfluoro fluororesin (hereinafter also simply referred to as fluororesin), wherein the ratio of hydrogenated acrylonitrile butadiene rubber to perfluoro fluororesin (solid mass ratio) is 25:75 to 55:45.
  • HNBR hydrogenated acrylonitrile butadiene rubber
  • fluororesin perfluoro fluororesin
  • the perfluoro fluororesin is a hot-melt perfluoro fluororesin
  • the hot-melt perfluoro fluororesin is tetrafluoroethylene hexafluoropropylene copolymer
  • the hydrogenated acrylonitrile butadiene rubber and the perfluoro fluororesin are aqueous dispersion solutions, and form an aqueous coating composition
  • composition ratio of the hydrogenated acrylonitrile butadiene rubber and the perfluoro fluororesin is 35:65 to 50:50.
  • the present invention also provides a rubber sealing member, comprising a surface with a coating film containing hydrogenated acrylonitrile butadiene rubber and perfluoro fluororesin in a composition ratio of 25:75 to 55:45 (solid mass ratio).
  • the perfluoro fluororesin is a hot-melt perfluoro fluororesin
  • the hot-melt perfluoro fluororesin is tetrafluoroethylene hexafluoropropylene copolymer
  • the tack force (peak value) received by a probe is 20 gf or less when a 5 mm diameter probe (SUS304 material) at room temperature is pressed against the coating film at a speed of 5 mm/min and a load of 100 gf, held at a load of 100 gf for 3 seconds, and then pulled away at a speed of 10 mm/min; and
  • the rubber sealing member is a seal ring, gasket, valve seal or check valve.
  • the coating composition for a rubber sealing member of the present invention can impart tack-free (non-tacking) properties to rubber sealing members to prevent any adhesion whatsoever even after light contact with metal, which is the opposing material, as well as excellent abrasion resistance, in order to enable suitable expression of the sealing performance expected of rubber sealing members, and the excellent tack-free properties can be maintained for a long period of time.
  • the coating composition for a rubber sealing member of the present invention can form a coating film with excellent tracking properties at low temperature, even for rubber sealing members that are elastic and do not have high heat resistance.
  • the coating composition also has excellent durability.
  • the coating composition for a rubber sealing member can be a water-based coating composition where HNBR and fluororesin are dispersed in water, which is excellent from an environmental and cost perspective.
  • rubber sealing members such as seal rings and check valves that have a coating film made of the coating composition of the present invention have excellent tack-free properties and do not stick when in contact with metal, and thus the sealing performance of the rubber sealing member is maintained without loss.
  • the coating composition can also form a coating film at low temperature on the surface of a rubber sealing member that has poor heat resistance, and thus the coating composition has excellent productivity.
  • the coating composition for a rubber sealing member of the present invention is a coating composition containing hydrogenated acrylonitrile butadiene rubber and perfluoro fluororesin, and the composition ratio of the HNBR to the fluororesin (solid mass ratio) is 25:75 to 55:45, and a ratio of 35:65 to 50:50 is particularly preferable. If the amount of HNBR blended is less than the aforementioned range, forming a contiguous coating film will be more difficult than in the aforementioned range, which may cause coating film defects such as cracks, and may reduce adhesion between the rubber sealing member and the coating film. On the other hand, if the amount of HNBR added is higher than the aforementioned range, achieving the desired tack-free properties in the coating film will be more difficult than when the amount is within the aforementioned range.
  • HNBR which serves as the base resin
  • the HNBR is used in an unvulcanized condition and is vulcanized when forming the coating film.
  • the vulcanization treatment temperature can be 200°C or lower (and preferably 180°C or lower). Therefore, the coating composition of the present invention can be used without any problem on a rubber sealing member that can be used at or above that temperature.
  • the HNBR preferably has a hydrogenation ratio of 80 to 99%. Furthermore, the acrylonitrile content should be in a range of 18 to 50% by mass. Furthermore, the Mooney viscosity ML (1 + 4) at 100 °C (in accordance with JIS K6300) is preferably within a range of 30 to 150.
  • aqueous dispersions (latex) of HNBR prepared by conventionally known methods are suitably used.
  • the inclusion of perfluoro fluororesin reduces the surface energy of the coating film, which improves the slipperiness and controls the tack-free properties of the coating film. Furthermore, wear resistance is also improved by reducing the coefficient of friction. Thus, the tack-free properties are maintained over a long period of time, and therefore, the durability is also improved.
  • perfluoro fluororesins examples include polytetrafluoroethylene (PTFE); hot-melt perfluoro fluororesins such as low molecular weight polytetrafluoroethylene (low molecular weight PTFE), tetrafluoroethylene perfluoro (alkylvinyl ether) copolymer (PFA), tetrafluoroethylene hexafluoropropylene copolymer (FEP), tetrafluoroethylene/hexafluoropropylene/perfluoro (alkyl vinyl ether) copolymer, and the like.
  • PTFE polytetrafluoroethylene
  • hot-melt perfluoro fluororesins especially FEP, can be suitably used.
  • the FEP may be a copolymer containing only tetrafluoroethylene (TFE) and hexafluoropropylene (HFP), or a copolymer containing polymerized units of TFE, HFP, and monomers that can copolymerize with TFE and HFP.
  • TFE tetrafluoroethylene
  • HFP hexafluoropropylene
  • Polymer units based on monomers that can copolymerize with TFE and HFP include perfluoro(alkyl vinyl ether), and the like.
  • TFE tetrafluoroethylene
  • the melt flow rate (MFR) of the hot-melt fluoropolymer should be 1 to 100 g/10 min, more preferably 1 to 80 g/10 min, and even more preferably 1 to 50 g/10 min. MFR is measured in accordance with ASTM D1238 using a melt indexer at a temperature of 372°C and a weight of 5 kg.
  • the fluororesin can be used as powder particles of fluororesin, the fluororesin particles are preferably finely dispersed in the coating film to achieve excellent tack-free properties. Therefore, the dispersion obtained by emulsion polymerization is preferably added and used as a raw material for a coating.
  • the average particle diameter of the fluororesin particles is preferably 0.5 pm or less, and particularly preferably 0.3 pm or less. With the present invention, the average particle size refers to the particle size at an integrated value of 50% in the particle size distribution determined by a laser diffraction and scattering method.
  • a silane coupling agent is preferably included in order to improve adhesion between the coating film and the rubber sealing member.
  • silane coupling agents can be used as the silane coupling agent that can be used in the coating composition of the present invention, and examples can include, but are not limited to, y-(2- aminoethyl) aminopropyltrimethoxysilane, y-aminopropyltriethoxysilane, N-p (aminoethyl) y-aminopropyltrimethoxysilane, N-p (aminoethyl) y- aminopropylmethyldimethoxysilane, and other silane coupling agents containing an amino group; y-glycidoxypropyltrimethoxysilane, y- glycidoxypropylmethyldimethoxysilane, and other silane coupling agents containing a glycidyl group; y-mercaptopropyltrimethoxysilane and other silane coupling agents containing a mercapto group; vinyltriethoxysilane,
  • (meth)acryloyloxypropyldimethoxymethylsilane and other silane coupling agents containing a (meth)acryloyl group; y-isocyanate propyltriethoxysilane, y-isocyanate propyltrimethoxysilane, and other silane coupling agents containing an isocyanate group; and the like.
  • the silane coupling agent should be blended in an amount of 0.5 to 3.0% by mass, especially 0.8 to 2.5% by mass, based on the solid content of the total resin (sum of HNBR and fluoropolymer) in the coating composition. If the amount of the silane coupling agent is less than the aforementioned range, the aforementioned effect obtained by mixing the silane coupling agent cannot be sufficiently achieved. On the other hand, if the amount of silane coupling agent is higher than the aforementioned range, the tack-free properties of the coating film may be impaired as compared to when in the aforementioned range.
  • the coating composition according to the present invention may be any form of water or solvent based coating composition or powder coating composition, but the composition is, from an environmental perspective, preferably a water-based coating composition.
  • exemplary methods for preparing the coating composition include, but are not limited to, the methods described below.
  • the coating composition of the present invention is prepared as a water based coating composition
  • the coating composition can be prepared by a method of mixing: an aqueous dispersion of HNBR (latex) or a precursor solution of HNBR, prepared by a conventionally known method; an aqueous dispersion or mixture of fluororesin particles (for example, an existing fluororesin water based coating or the like), at a ratio (solid mass ratio) of 25:75 to 55:45; and if necessary, a silane coupling agent, or another additive as described below.
  • HNBR latex
  • a precursor solution of HNBR prepared by a conventionally known method
  • fluororesin particles for example, an existing fluororesin water based coating or the like
  • the aqueous dispersion of HNBR can be prepared by a conventionally known method, and can be prepared by, but not limited to, emulsion polymerization, suspension polymerization, a method using an emulsifying device such as a high-speed homogenizer or the like, an inversion emulsification method, a phase inversion temperature emulsification method, and an emulsification method using a surfactant, or the like.
  • HNBR particles having an average particle diameter of 0.01 to 0.5 pm are preferably dispersed to be 10 to 70% by weight in the aqueous dispersion.
  • the aqueous dispersion of fluororesin particles used in the coating composition can be prepared by dispersing the fluororesin uniformly and stably in an aqueous medium using a surfactant or the like, or by water based emulsion polymerizing the fluororesin using a surfactant and an initiator, or, if necessary, a chain transfer agent or the like.
  • aqueous dispersions of fluororesins prepared from aqueous dispersions obtained by aqueous emulsion polymerization can also be used.
  • the fluororesin particles having an average particle diameter of 0.01 to 180 pm are preferably dispersed to be 10 to 70% by weight in the aqueous dispersion.
  • aqueous dispersions of fluororesin particles having an average particle diameter of 0.1 to 0.3 pm are preferably used.
  • the aqueous dispersion of the aforementioned HNBR and an aqueous dispersion of fluororesin may be used as is, but a filler and various additives used in an ordinary coating may be added in accordance with required characteristics, such as dispersibility, conductivity, foaming prevention, wear resistance improvement, and the like.
  • Examples can include surfactants (examples thereof include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether type nonionic surfactants; such as LEOCOL® manufactured by LION, Inc., the TRITON® and TERGITOL® series manufactured by the Dow Chemical Company, and EMULGEN® manufactured by KAO, Inc., sulfosuccinates; such as LIPAL® manufactured by LION, Inc., EMAL®, PELEX® manufactured by KAO, Inc., and the like, anionic surfactants; such as alkyl ether sulfonic acid sodium salts, sulfate mono-long chain alkyl type, and polycarboxylate, acrylic salt type polymer surfactants, such as, LEOARL® manufactured by LION, Inc., OROTAN® manufactured by the Dow Chemical Company, and the like), film forming agents (examples include polymeric film forming agents such as polyamides, polyamide imides, acrylics, acetates
  • the water-based coating composition of the present invention can be prepared by mixing and stirring a water-based dispersion of HNBR prepared by the aforementioned method, a water-based dispersion of a fluororesin, or an aqueous composition (solution, ready-made coating, or the like).
  • aqueous coating composition water is preferred as the main medium from the perspective of the environmental and costs.
  • a polar solvent that is compatible with water can be added from the perspective of adjusting rheological properties such as the viscosity of the coating composition, improving the dispersibility of fillers, or improving the volatility of the solvent when drying after coating to form a uniform paint film.
  • Examples of these polar solvents include, but are not limited to, methanol, ethanol, 1 -propanol, 2-propanol, ethylene glycol, diethylene glycol, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol hexyl ether, diethylene glycol hexyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, ethylene glycol phenyl ether, propylene glycol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, propylene glycol,
  • a solvent-based coating composition can be prepared by preparing liquid HNBR, an HNBR solvent dispersion, fluororesin solution, or fluororesin solvent dispersion, and then stirring and mixing.
  • Various types of exemplified additives for water-based coating compositions can be used.
  • the aqueous dispersion of HNBR and aqueous dispersion of fluororesin prepared by the above methods can be prepared by agitating to coagglomerate the HNBR and the fluororesin.
  • composite powder containing primary particles of HNBR and fluororesin can be prepared by agitating at a speed of 100 to 500 rpm for 1 to 60 minutes in order to granulate agglomerated granules with an average particle diameter of 1 to 200 pm, followed by separation, washing and drying. Large coarse particles with particle diameters of at least 200 pm generated by aggregation or over-granulation can be crushed into fine particles as necessary.
  • an electrolytic material such as HCI, H2SO4, HNO3, H3PO4, Na 2 SO 4 , MgCI 2 , CaCI 2 , HCOONa, CH3COOK, (NH 4 ) 2 CO 3 , or the like is preferably added to chemically aggregate rubber/fluororesin primary particles.
  • an organic solvent incompatible with water preferably a fluorinated solvent is preferably added as needed so as to uniformly granulate the aggregated particles.
  • organic and inorganic fillers can be added to the coating composition according to the present invention, based on the characteristics required thereof.
  • examples of organic fillers include engineering plastics, such as polyarylene sulfides, polyether ether ketones, polyamides, polyimides, and the like.
  • Exemplary inorganic fillers include metal powders, metal oxides (aluminum oxide, zinc oxide, tin oxide, titanium oxide, etc.), glass, ceramics, silicon carbides, silicon oxides, calcium fluorides, carbon black, graphites, micas, barium sulfates, etc.
  • Various shapes of fillers can be used, such as particles, fibers, flakes, and the like. However, in order to obtain the flexibility in the coating film required for the coating composition of the present invention, a particle shaped filler with low anisotropy is preferably used, and a spherical filler is more preferably used.
  • a pigment and various additives conventionally used in coatings can be added in accordance with required characteristics, such as electrical conductivity, foam prevention, improved wear resistance, improved corrosion resistance, coloring, and the like.
  • fillers can be used to provide various properties to the coating film.
  • amount of filler cannot be generally specified depending on the type of filler used, a range of 0.1 to 10% by mass of coating solid in the coating composition (total amount of HNBR, fluororesin, and filler) is preferable. If the amount of added filler is below this range, the improvement to the properties due to the added filler will be insufficient, but if the amount is above this range, tack-free properties will be inferior and the elasticity will be degraded as compared to a case where the amount is in the aforementioned range.
  • the filler can be used by dispersing the filler in a liquid medium such as water or the like.
  • the coating composition of the present invention can be coated on a surface of a rubber sealing member by a conventionally known coating method such as spray coating, dip coating, and the like.
  • the coated coating composition is heat treated to the crosslinking temperature of the HNBR to form a coating film.
  • the crosslinking temperature of the HNBR is as low as 120 to 200°C. Therefore, even if the coating is applied directly to a rubber sealing member and heat treated, a uniform coating film can be formed without damaging the rubber sealing member.
  • heating conditions (baking conditions) of the coating composition of the present invention vary depending on the composition and form of the coating composition, the amount of coating, the desired crosslinking temperature, and the like, and thus cannot be generally specified.
  • the coating composition is preferably heated at a temperature higher than the crosslinking temperature of the HNBR for 5 to 120 minutes. Furthermore, crosslinking can be accelerated by performing the heat treatment a plurality of times, and wear resistance can also be improved.
  • the coating composition of the present invention has excellent adhesion to the rubber sealing member, and therefore can be coated directly onto a substrate surface without requiring a primer layer, surface treatment of the substrate, and the like.
  • the paint composition of the present invention can form a coating film at low temperature, can provide excellent tack-free (non-tacking) properties so as to not adhere whatsoever when lightly touched to metal, has excellent adhesion to rubber substrates, and has elasticity that can track the expansion and contraction of the rubber substrate. Therefore, the composition is suitable for use as a surface coating on rubber sealing members that come in contact with metal as an opposing material, such as O- rings, oil seals, gaskets, valve seals, or check valves such as umbrella type check valves and the like.
  • Rubber sealing members can be molded from various rubbers or thermoplastic elastomers (collectively referred to as "rubber materials”), depending on the type and application.
  • examples of the rubber include saturated polyolefin based rubbers such as ethylene-propylene copolymers, ethylene-a-olefin copolymers, propylene-a-olefin copolymers, chlorinated polyethylene, and chlorosulfonated polyethylene; a-olefin diene copolymer rubbers such as ethylene-propylene-diene copolymers, a-olefin-diene copolymers, ethylene-diene copolymers, propylene-diene copolymers, and halides and hydrogenated products thereof; diene copolymer rubbers such as isoprene rubbers, butadiene rubbers, and halides and hydrogenated products thereof, silicone based rubbers such as methyl silicone rubbers, vinyl methyl silicone rubbers, and phenyl methyl silicone rubbers; fluorine rubbers such as fluorinated silicone rubbers, fluorinated vinylidene rubbers,
  • thermoplastic elastomers include polystyrene based thermoplastic elastomers such as styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylene- butadiene-styrene block copolymers, styrene-isoprene-butadiene-styrene block copolymers, and styrene-ethylene-propylene-styrene block copolymers, and halides and hydrogenated products thereof; polyolefin based thermoplastic elastomers such as blends of olefin resins and olefin rubbers and blends of olefin resins and olefin-diene copolymers, and halides and hydrogenated products thereof; polyurethane based thermoplastic elastomers, polyester based thermoplastic elastomers
  • the paint composition of the present invention can provide the desired tack-free properties toward metals while maintaining excellent adhesion, especially to sealing members made of fluorine rubber, butyl rubber, and ethylene-propylene rubber (EPM, EPDM).
  • a crosslinking agent, polymerization initiator, filler, pigment, ultraviolet absorber, anti-aging agent, foaming agent, antifoaming agent, antioxidant, or the like can be added based on a conventional known formulation to the aforementioned rubber material forming the rubber sealing member.
  • the coating film formed from the coating composition of the present invention has excellent durability and is able to maintain tack-free properties (non-tacking properties) over a long period of time, and therefore the composition is particularly suitable for use as a coating for covering a surface of automotive seal rings or the like.
  • the thickness of the surface coating film of the rubber sealing member can be selected according to the type of sealing member and the application, or the like. However, when the rubber sealing member is used to provide tack-free properties to a sealing ring or check valve as described above, the coating should be applied such that the film thickness after heat treatment is 5 pm or more, especially 5 to 300 pm. If the film thickness is thinner than the above range, a continuous coating film cannot be formed as compared to when the film thickness is in the aforementioned range, which may cause coating film defects and may also cause early loss of coating film performance (tack-free properties and slipperiness) due to wear. On the other hand, even if the film thickness is thicker than the aforementioned range, further improvement in coating performance, such as tack-free properties, cannot be expected, and thus the economic efficiency thereof is inferior.
  • the coating film formed on the surface of the rubber sealing member has excellent tack-free properties and does not stick to metal. Therefore, a sealing member with this coating film formed on a surface will exhibit excellent sealing performance as a sealing member.
  • the coating film formed on the surface of the rubber sealing member has a contact angle with pure water of 90 degrees or more, preferably 95 degrees or more, indicating high tack-free properties from this perspective.
  • the coating film formed on the surface of the rubber sealing member has excellent adhesive strength (adhering power) to the rubber sealing member.
  • a rubber sealing member with this coating film formed on the surface can have excellent and stable tack-free properties, abrasion resistance, elasticity, and the like, of the coating film over a long period of time.
  • a method for measuring peel strength against rubber sealing members is described below.
  • Fluorinated vinylidene rubber (FKM) (size: 100 mm x 50 mm x 2 mm thick, manufactured by Paltec Co., Ltd.)
  • EPDM Ethylene propylene diene rubber
  • a coating was performed by spraying the coating compositions of the examples and comparative examples described below to an air blown substrate using an air spray coating gun (W-88-10E2 ⁇ p 1 mm nozzle (manual gun), manufactured by Anest Iwata Corporation) at an air pressure of 2.5 to 3.0 kgf/cm 2 .
  • Test pieces were fabricated by coating the coated liquid mass so as to be approximately 0.65 g (0.60 to 0.70 g) per substrate. Note that the baking conditions are as follows.
  • the tack force (peak value) (gf) received by a probe was measured using a TAG 1000 Tacking tester made by Rhesca Corporation by pressing a 5 mm diameter probe (SUS304 material) at room temperature against the coating film at a speed of 5 mm/min and a load of 100 gf, maintaining the load of 100 gf for 3 seconds, and then pulling away at a speed of 10 mm/min.
  • the results are shown in Table 2.
  • the contact angle (°) (droplet size: approximately 2 pL) of pure water was measured using a fully automatic contact angle meter (Kyowa Interface Science Co., Ltd., DM-701 ) in a measurement environment at 25°C and relative humidity of 60%. The results are shown in Table 2.
  • Scotch tape® is strongly pressed against the grid square portion, an edge of the tape is peeled off at an angle of 45 degrees at once, and then the condition of the grid square is evaluated.
  • Dumbbell-shaped specimens (in accordance with ASTM D-2116) were cut out from a test piece made by coating the coating compositions of Examples 2 to 5 onto a butyl rubber (HR) sheet, and then a stretching test was performed with a constant stretching repeated fatigue tester (MYSS Tester, H9537/H9606 manufactured by MYS-TESTER Company Limited) under the following conditions:
  • test pieces were subjected to a wear resistance test performed using a Suga Wear Testing Machine NUS-ISO3 available from Suga Test Instruments Co., Ltd., in accordance with JIS K5600-5-10 (test piece reciprocating method). The test conditions were as described below.
  • Abrasive paper used Silicon carbide paper, P-400 grade (12 mm wide)
  • N number of reciprocations (ds: double strokes)
  • the density p was a calculated value calculated from the composition ratios shown in Table 1 , using 1.02 g/cm 3 as the average specific gravity value for HNBR and 2.15 g/cm 3 as the average specific gravity value for FEP, PFA, and PTFE.
  • aqueous carbon black dispersion adjusted to a concentration of 25% by mass was added to the above mixture and stirred at 250 rpm for 5 minutes.
  • 16.10 g of a 6% methylcellulose aqueous solution and 2.46 g of a silane coupling agent (KBM-603 manufactured by Shin-Etsu Chemical Co., Ltd.) were added thereto and then stirred at 250 rpm for 15 minutes to obtain 500 g of a coating composition.
  • Coating compositions were prepared by the same procedures as Example 1 , and the composition ratio of fluoropolymer (FEP) and HNBR in the coating was adjusted to the proportions shown in Table 1 to achieve the same concentrations as in Example 1.
  • FEP fluoropolymer
  • a coating composition was prepared with the same content ratio as in Example 3, except that a PFA aqueous dispersion (Teflon® PFA 334-JR manufactured by Chemours-Mitsui Fluoro products Co., Ltd., PFA resin solid fraction: 60.0% by weight) was used as the fluororesin. (Example 5)
  • a coating composition was prepared with the same content ratio as in Example 3, except that a PTFE aqueous dispersion (Teflon® PTFE 31 -JR manufactured by Chemours-Mitsui Fluoroproducts Co., Ltd., PTFE resin solid fraction: 59.4% by weight) was used as the fluororesin.
  • a PTFE aqueous dispersion Teflon® PTFE 31 -JR manufactured by Chemours-Mitsui Fluoroproducts Co., Ltd., PTFE resin solid fraction: 59.4% by weight
  • a coating composition was prepared by the same procedure as in Example 1 so as to have the same resin solid content (sum of fluoropolymer and HNBR) as the coating composition of Example 1 , using only HNBR without using a fluororesin.
  • the coating composition for a rubber sealing member of the present invention can form a coating film that provides excellent tack-free properties towards metal over a long period of time, and can be suitably used as a coating for rubber sealing parts such as seal rings, gaskets, valve seals, check valves, and the like.

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Organic Chemistry (AREA)
  • Paints Or Removers (AREA)
  • Sealing Material Composition (AREA)

Abstract

L'invention vise à fournir une composition de peinture apte à former un film de revêtement ayant une excellente durabilité, qui peut être utilisée pour des éléments d'étanchéité en caoutchouc utilisés en contact avec du métal, et qui peut présenter une excellente adhérence à l'élément d'étanchéité lui-même et une absence d'adhésivité au produit métallique qui est le matériau homologue sur une longue période de temps. L'invention concerne une composition de peinture pour des éléments d'étanchéité en caoutchouc contenant du caoutchouc acrylonitrile butadiène hydrogéné et de la perfluorofluororésine, le rapport dudit caoutchouc acrylonitrile butadiène hydrogéné à ladite perfluorofluororésine (rapport en masse solide) étant de 25:75 à 55:45.
PCT/US2024/029825 2023-05-18 2024-05-17 Composition de revêtement pour élément d'étanchéité en caoutchouc Pending WO2024238873A1 (fr)

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JP2023082365A JP2024165833A (ja) 2023-05-18 2023-05-18 ゴム製シール部材用塗料組成物
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8287737B2 (en) * 2007-09-28 2012-10-16 Ge Healthcare Bio-Sciences Ab Sealing assembly for a chromatography column
US20150252181A1 (en) * 2012-09-25 2015-09-10 Nok Corporation Coating agent composition
US20200362940A1 (en) * 2018-10-17 2020-11-19 Bando Chemical Industries, Ltd. Toothed belt
WO2021014901A1 (fr) 2019-07-25 2021-01-28 Nok株式会社 Agent de revêtement pour joint étanche à l'huile
WO2022192118A1 (fr) * 2021-03-08 2022-09-15 The Chemours Company Fc, Llc Composition de revêtement

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8287737B2 (en) * 2007-09-28 2012-10-16 Ge Healthcare Bio-Sciences Ab Sealing assembly for a chromatography column
US20150252181A1 (en) * 2012-09-25 2015-09-10 Nok Corporation Coating agent composition
US20200362940A1 (en) * 2018-10-17 2020-11-19 Bando Chemical Industries, Ltd. Toothed belt
WO2021014901A1 (fr) 2019-07-25 2021-01-28 Nok株式会社 Agent de revêtement pour joint étanche à l'huile
WO2022192118A1 (fr) * 2021-03-08 2022-09-15 The Chemours Company Fc, Llc Composition de revêtement
JP2022136748A (ja) 2021-03-08 2022-09-21 三井・ケマーズ フロロプロダクツ株式会社 塗料組成物

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