Classifications

• • 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
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells

Definitions

• hot melt adhesive compositions have come to be used as adhesive films or sheets (hereinafter collectively referred to as "adhesive members") in chemical batteries such as lithium ion batteries and fuel cells that are incorporated into notebook computers, smartphones, tablets, automobiles, etc., as well as physical batteries such as solar cells and capacitors. It is known that relatively good adhesive strength can be obtained by using hot melt adhesive compositions whose main component is an acid-modified olefin thermoplastic resin (hereinafter also referred to as “acid-modified polyolefin”) to bond metal substrates such as iron, aluminum, titanium, and other metals, as well as alloys thereof, which are used as the substrates for the components of these batteries.
• acid-modified polyolefin an acid-modified olefin thermoplastic resin
• Patent Document 2 describes a gasket member for a polymer electrolyte fuel cell that is composed of a laminate that includes at least a base layer and adhesive layers disposed on both sides of the base layer, and the laminate has a breaking elongation retention rate of 60% or more after being left in water at 120°C for 300 hours.
• Patent Document 1 JP 2018-135467
• Patent Document 2 WO 2022/172983
• a multilayer sheet comprising, in this order, a base layer, a primer layer disposed on at least one surface side of the base layer, and an adhesive layer, wherein the base layer contains a polymer having a structural unit containing at least one structure selected from the group consisting of an imide structure, a sulfone structure, an amide structure, and a sulfide structure, and the primer layer contains an acid-modified polyolefin.
• the primer layer further contains a curing agent.
• the curing agent contains at least one selected from an isocyanate compound and an epoxy compound.
• the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range.
• the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.
• the molecular weight of a compound having a molecular weight distribution is the weight average molecular weight (Mw).
• Mw weight average molecular weight
• “mass %” and “weight %” are synonymous, and “parts by mass” and “parts by weight” are synonymous.
• combinations of two or more preferred aspects are more preferred aspects.
• the substrate layer is an intermediate layer or a surface layer
• the adhesive layer is a surface layer
• the primer layer is an intermediate layer
• only the primer layer may be the intermediate layer, and both the base layer and the adhesive layer may be surface layers.
• Typical layer configurations of multilayer sheets include a three-layer sheet of substrate layer/primer layer/adhesive layer, and a five-layer sheet of adhesive layer/primer layer/substrate layer/primer layer/adhesive layer.
• the multilayer sheet according to the present disclosure comprises, in this order, a base layer, a primer layer disposed on at least one side of the base layer, and an adhesive layer. It is presumed that the base layer contains a specific polymer and the primer layer contains an acid-modified polyolefin, thereby improving hydrolysis resistance even in high temperature and moisture-containing environments, and providing excellent adhesion durability.
• the adhesive durability is measured by applying the adhesive layer of the multilayer sheet to an adherend (specifically, a thickness of 0.
• a test piece is prepared from the bonded body obtained by bonding the test piece to a SUS304 plate (1 mm thick), and the test piece is kept in water at 120° C. for 1500 hours, after which the peel strength is evaluated. Details of the evaluation method and conditions for adhesion durability will be described in the Examples section below.
• the structural unit of the specific polymer may contain one type of structure selected from the group consisting of an imide structure, a sulfone structure, an amide structure, and a sulfide structure (hereinafter also referred to as a "specific structure"), or may contain two or more types.
• the total amount of the specific polymer in the substrate layer is preferably 60% by mass or more, more preferably 70% by mass or more. There is no particular upper limit to the total amount of the specific polymer in the substrate layer, but in one embodiment of the present disclosure, the total amount of the specific polymer in the substrate layer is preferably 99.9% by mass or less, more preferably 98% by mass or less, and even more preferably 95% by mass or less.
• the base layer may contain a polymer other than the specific polymer (hereinafter also referred to as "other polymer A”) for the purposes of heat resistance, hydrolysis resistance, ease of formability, etc.
• other polymer A a polymer other than the specific polymer
• polymer A examples include, for example, phenol resin, urea resin, melamine resin, benzoguanamine resin, alkyd resin, unsaturated polyester resin, vinyl ester resin, diallyl terephthalate resin, silicone resin, urethane resin, furan resin, ketone resin, xylene resin, benzoxazine resin, active ester resin, aniline resin, cyanate ester resin, styrene-maleic anhydride (SMA) resin, polyethylene resin, polypropylene resin, polystyrene resin, rubber-modified polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene (AS) resin, polymethyl methacrylate resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyethylene terephthalate resin, ethylene vinyl alcohol resin, etc.
• SMA styrene-maleic anhydride
• the resin examples include polyolefin resins, cellulose acetate resins, ionomer resins, polyacrylonitrile resins, polyacetal resins, polybutylene terephthalate resins, polylactic acid resins, polyphenylene ether resins, modified polyphenylene ether resins, polycarbonate resins, polyarylate resins, polyether ether ketone resins, polyketone resins, liquid crystal polyester resins, fluororesins, syndiotactic polystyrene resins, cyclic polyolefin resins, ⁇ -olefin copolymers, propylene-based elastomers, polyisoprene, hydrogenated polyisoprene, polybutadiene, cycloolefin polymers, cycloolefin copolymers, polyamines, polyamides, melamine resins, urea resins, styrene-based thermoplastic resins, hydroxyl group
• the content of other polymer A in the base layer is preferably 50% by mass or less, more preferably 35% by mass or less, and particularly preferably 20% by mass or less.
• the multilayer sheet can further improve the heat resistance, hydrolysis resistance, and ease of formability.
• the storage modulus of the base layer at 160°C is preferably 500 MPa or more, more preferably 700 MPa or more, and particularly preferably 1000 MPa or more.
• the storage modulus of the base layer at 170°C is preferably 500 MPa or more, more preferably 700 MPa or more, and particularly preferably 1000 MPa or more. If the storage modulus in this temperature range is 500 MPa or more, deformation and damage to the multilayer sheet due to thermocompression during adhesion can be prevented.
• the thickness change rate of the base layer in a compression creep test is preferably 30% or less, more preferably 25% or less, and particularly preferably 20% or less.
• the thermal change rate of the base layer in a heat shrinkage test is preferably 0.50% or less, more preferably 0.30% or less, and particularly preferably 0.20% or less.
• the softening point and storage modulus are values determined using a tensile viscoelasticity device (DMS6100 manufactured by Hitachi High-Tech Sanence Corporation). Specifically, the object to be measured is heated from room temperature to 250°C at a frequency of 1 Hz and a heating rate of 2°C/min, and the changes in storage modulus, loss modulus, and tan ⁇ with temperature are recorded.
• the softening point refers to the temperature at which tan ⁇ is at its maximum.
• the melt flow rate of the base layer is a value measured in accordance with JIS K7210:2014 (ISO 1133 2011).
• the melt flow rate of the base layer was measured at a resin temperature of 300°C and a load of 2.16 kg.
• the substrate layer may further include an additive selected from the group consisting of antioxidants, UV absorbers, fillers, reinforcing fibers, release agents, processing aids, flame retardants, plasticizers, nucleating agents, antistatic agents, pigments, dyes, foaming agents, and combinations thereof.
• an additive selected from the group consisting of antioxidants, UV absorbers, fillers, reinforcing fibers, release agents, processing aids, flame retardants, plasticizers, nucleating agents, antistatic agents, pigments, dyes, foaming agents, and combinations thereof.
• the primer layer contains an acid-modified polyolefin.
• the content of the acid-modified polyolefin in the primer layer is preferably 50% by mass or more, more preferably 70% by mass or more, based on the total amount of the primer layer.
• the content of the acid-modified polyolefin is in such a range, the effect of improving the adhesion durability of the primer layer is enhanced.
• Unsaturated carboxylic acids are compounds that have an ethylenic double bond and a carboxylic acid group in the same molecule, and examples include various unsaturated monocarboxylic acids and unsaturated dicarboxylic acids. These acid compounds may be used alone or in combination of two or more types.
• maleic acid and maleic anhydride are preferably used because of their high modifying effect, and maleic anhydride is particularly preferably used.
• the acid-modified polyolefin contained in the primer layer is preferably maleic anhydride-modified polyolefin.
• the temperature for the grafting reaction is preferably 80 to 160°C when the reaction is carried out in a solution state, and 150 to 300°C when the reaction is carried out in a molten state.
• the reaction rate is high at or above the lower limit of the reaction temperature range mentioned above, and the decrease in the molecular weight of the resin can be suppressed at or below the upper limit of the reaction range mentioned above, and the mechanical strength of the resulting acid-modified polyolefin can be maintained.
• the amount of acid compound grafted to the acid-modified polyolefin is preferably 0.2 mass% or more, more preferably 0.4 mass% or more, and particularly preferably 0.6 mass% or more.
• the amount of the grafted acid compound is within such a range, the adhesion of the primer layer can be improved.
• the amount of the acid compound grafted to the acid-modified polyolefin is defined by the following formula based on the acid value of the acid-modified polyolefin.
• Graft amount (mass%) acid value ⁇ M ⁇ 100/(1000 ⁇ 56.1 ⁇ V)
• V valence of acid group (however, in the case of containing an acid anhydride group, this is the valence of the acid group when the acid anhydride group is completely hydrolyzed)
• the acid value indicates the number of milligrams of potassium hydroxide required to neutralize the acid contained in 1 g of a sample, and is measured in accordance with JIS K 0070:1992.
• the melting point of the acid-modified polyolefin is preferably 50°C or higher, and more preferably 60°C or higher. If the melting point of the acid-modified polyolefin is within this range, the heat resistance and adhesive strength at high temperatures of the primer layer can be further improved.
• the melting point of the acid-modified polyolefin is preferably 160°C or less, and more preferably 100°C or less. If the melting point of the acid-modified polyolefin is within this range, good thermocompression bonding properties can be obtained, and the adhesive durability at low temperatures can be improved.
• the acidic polyolefin contained in the primer layer may be a commercially available product.
• commercially available acidic polyolefins include "MODIC” manufactured by Mitsubishi Chemical Corporation, “ADMER” and “UNISTOLL” manufactured by Mitsui Chemicals, Inc., “TOYOTAC” manufactured by Toyobo Co., Ltd., “UMEX” manufactured by Sanyo Chemical Industries, Ltd., “REXPERL EAA” and “REXPERL ET” manufactured by Japan Polyethylene Co., Ltd., "PRIMACOL” manufactured by Dow Chemical Co., Ltd., "NUCREL” manufactured by Mitsui-DuPont Polychemicals, and “BONDINE” manufactured by Arkema.
• the primer layer may contain a polymer other than the above-mentioned acid-modified polyolefin (hereinafter also referred to as "other polymer B") for the purpose of improving adhesion, hydrolysis resistance, heat resistance, etc.
• other polymer B may be one type or two or more types.
• polymer B examples include phenolic resin, urea resin, melamine resin, benzoguanamine resin, alkyd resin, unsaturated polyester resin, vinyl ester resin, diallyl terephthalate resin, silicone resin, urethane resin, furan resin, ketone resin, xylene resin, thermosetting polyimide resin, benzoxazine resin, active ester resin, aniline resin, cyanate ester resin, styrene-maleic anhydride (SMA) resin, polyethylene resin, polypropylene resin, polystyrene resin, rubber-modified polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene (AS) resin, polymethyl methacrylate resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyethylene terephthalate resin, ethylene vinyl alcohol resin, cellulose acetate resin, ionomer resin, poly
• the isocyanate compound is preferably a compound having two or more isocyanate groups (-NCO) (i.e., a polyfunctional isocyanate compound), and examples of such compounds include bifunctional diisocyanates, and trifunctional or higher isocyanates having structures such as adduct structures, isocyanurate structures, and biuret structures.
• -NCO isocyanate groups
• isocyanate compound commercially available products may be used.
• examples of commercially available isocyanate compounds include Duranate TPA-100, Duranate T4900-70B, Duranate MFA-75B, Duranate MHG80B, and Duranate 21S-75E (manufactured by Asahi Kasei Corporation), Takenate A-3, Takenate A-50, Takenate 500, Takenate 600, Stabio D-370N, and Stabio D-376N (manufactured by Mitsui Chemicals, Inc.).
• epoxy compounds include bisphenol type epoxy resins such as bisphenol A type epoxy resins (different from hydrogenated bisphenol A type epoxy resins) and bisphenol F type epoxy resins; hydrogenated bisphenol type epoxy resins; novolac type epoxy resins; biphenyl type epoxy resins; stilbene type epoxy resins; hydroquinone type epoxy resins; naphthalene skeleton type epoxy resins; tetraphenylolethane type epoxy resins; trishydroxyphenylmethane type epoxy resins; dicyclopentadiene phenol type epoxy resins; 3' alicyclic epoxy resins such as 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol, and the like; polyglycidyl esters of polybasic acids such as diglycidyl ester of hexahydrophthalic anhydride, and the like; sorbitol polyglycidyl ether, sorbitan polyg
• glycidyl ethers such as glycidyl ether, glycerol polyglycidyl ether, hexanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, and cyclohexanedimethanol diglycidyl ether; diene polymer type epoxy resins such as polybutadiene or polyisoprene; glycidyl amine type epoxy resins such as tetraglycidyldiaminodiphenylmethane, tetraglycidylbisaminomethylcyclohexane, diglycidylaniline, and tetraglycidylmetaxylylenediamine; and heterocycle-containing epoxy resins such as triazine or hydantoin.
• epoxy compound commercially available products may be used.
• examples of commercially available epoxy compounds include EPICLON HP7200, EPICLON HP4700, EPICLON HP4710 (manufactured by DIC Corporation), jER828, jER157S70 (manufactured by Mitsubishi Chemical Corporation), JP-100, JP-200 (manufactured by Nippon Soda Co., Ltd.), EPPN-501H, NC-7000 (manufactured by Nippon Kayaku Co., Ltd.), TETRAD-C, TETRAD-X (Mitsubishi Gas Chemical Co., Ltd.), etc.
• the amount of hardener to be added can be determined appropriately depending on the type and content of the acidic polyolefin, the type and content of the other polymer B, etc. Only one type of hardener may be used, or two or more types may be used.
• the amount of the isocyanate compound added is preferably 0.1% by mass to 50% by mass, more preferably 5% by mass to 40% by mass, and even more preferably 10% by mass to 35% by mass, relative to the content of the acid-modified polyolefin.
• the amount of the isocyanate compound added is within the above range, the adhesive durability of the multilayer sheet tends to improve, and shape stability tends to be easily obtained.
• the amount of the epoxy compound added is preferably 0.1% by mass to 40% by mass, more preferably 1% by mass to 30% by mass, and even more preferably 5% by mass to 20% by mass, relative to the content of the acid-modified polyolefin.
• the amount of the epoxy compound added is within the above range, the adhesive durability of the multilayer sheet tends to be improved and overcuring tends to be easily suppressed.
• additive X an additive selected from imidazole compounds, dioctyl tin laurate, amine compounds, phosphorus compounds, etc.
• additive X may be added to the primer layer.
• Additive X may be a catalyst added in order to promote the reaction of the curing agent.
• additive X The amount of additive X to be added can be determined appropriately depending on the type and amount of curing agent used, the type and amount of acid-modified polyolefin used, etc. Additive X may be used alone or in combination of two or more types.
• the primer layer may further include an additive selected from the group consisting of antioxidants, UV absorbers, fillers, reinforcing fibers, release agents, processing aids, flame retardants, plasticizers, nucleating agents, antistatic agents, pigments, dyes, foaming agents, and combinations thereof.
• an additive selected from the group consisting of antioxidants, UV absorbers, fillers, reinforcing fibers, release agents, processing aids, flame retardants, plasticizers, nucleating agents, antistatic agents, pigments, dyes, foaming agents, and combinations thereof.
• the adhesive layer is a layer that exhibits adhesion to an adherend.
• the adhesive layer is preferably a layer containing at least one selected from polyethylene, polypropylene, an ethylene-propylene copolymer, a styrene-based thermoplastic elastomer, polyester, polyamide, and an acid-modified polyolefin, and more preferably a layer containing an acid-modified polyolefin.
• examples of monomer units constituting the polyolefin include monomer units derived from monomers selected from the group consisting of ⁇ -olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, and 4-methyl-1-pentene, diene monomers such as butadiene, isoprene, and chloroprene, aromatic vinyl compounds such as styrene, and combinations thereof.
• the number of carbon atoms of the monomer is as follows: Preferably, it is 2 to 10, more preferably 2 to 5.
• Polyethylene is a polymer containing ethylene units as the main component, and may be either a homopolymer or a copolymer.
• polyethylene is a copolymer
• the content of ethylene units in the polyethylene is preferably 50% by mass or more, and may be 70% by mass or more.
• Specific examples of polyethylene include homopolymers such as low-density polyethylene, high-density polyethylene, and linear low-density polyethylene; copolymers such as ethylene-diene monomer copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid ester copolymers, and ethylene-methacrylic acid ester copolymers; and halogen-modified products such as chlorinated polyethylene.
• Polypropylene is a polymer containing propylene units as the main component, and may be either a homopolymer or a copolymer. When polypropylene is a copolymer, the content of propylene units in the polypropylene is 50% by mass or more, and may be 70% by mass or more. Specific examples of polypropylene include homopolymers such as amorphous polypropylene and crystalline polypropylene, copolymers such as propylene-diene monomer copolymer, and halogen-modified products such as chlorinated polypropylene.
• Ethylene-propylene copolymer is a polymer containing ethylene units and propylene units, and may be composed of only ethylene units and propylene units, or may further contain other monomer units in addition to ethylene units and propylene units.
• An example of an ethylene-propylene copolymer containing other monomer units is an ethylene-propylene-diene monomer copolymer.
• the total amount of ethylene units and propylene units in the ethylene-propylene copolymer is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.
• polyolefins also include reactive blends in which functional groups are reacted between different polymers in a molding machine, graft copolymers or block copolymers made of multiple segments, and compositions in which physical blends of these are microdispersed using them as compatibilizers.
• the total amount of ethylene units and propylene units is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.
• the mass ratio of ethylene units to propylene units contained in the polyolefin is preferably 10/90 to 40/60, more preferably 15/85 to 35/65. When the mass ratio of ethylene units is equal to or greater than the lower limit of this range, the thermocompression bondability of the acid-modified polyolefin is improved, and the adhesive strength can be improved.
• the mass ratio of ethylene units is equal to or less than the upper limit of this range, the adhesive strength at high temperatures can be improved.
• the mass ratio of ethylene units to propylene units within the range shown above, it is possible to achieve both adhesive durability at high temperatures and adhesive durability at low temperatures.
• the "mass ratio of ethylene units and propylene units contained in the polyolefin" means the mass ratio of ethylene units and propylene units in all ethylene units and propylene units contained in the polyethylene and polypropylene.
• the mass ratio of ethylene units and propylene units is determined from the absorbance ratio of the characteristic absorption of polyethylene (719 cm -1 ) and the characteristic absorption of polypropylene (1167 cm -1 ) in the IR spectrum. Specifically, a calibration curve is used to convert the absorbance ratio of ethylene units and propylene units to a mass ratio.
• the calibration curve can be created by blending commercially available polyethylene and polypropylene at various ratios and plotting the blending ratio and the absorbance ratio.
• Polyethylene, polypropylene and ethylene-propylene copolymers may contain monomer units other than ethylene units and propylene units.
• monomers that form monomer units other than ethylene units and propylene units include ⁇ -olefins such as 1-butene, 1-pentene, 1-hexene, and 4-methyl-1-pentene, diene monomers such as butadiene, isoprene, and chloroprene, unsaturated carboxylic acids and derivatives thereof such as vinyl acetate, acrylic acid esters, acrylic acid, methacrylic acid, and methacrylic acid esters, and aromatic vinyl compounds such as styrene.
• ⁇ -olefins such as 1-butene, 1-pentene, 1-hexene, and 4-methyl-1-pentene
• diene monomers such as butadiene, isoprene, and chloroprene
• unsaturated carboxylic acids and derivatives thereof such as vinyl acetate, acrylic acid esters
• the content of monomer units other than ethylene units and propylene units in polyolefins is preferably 30% by mass or less, more preferably 20% by mass or less, and particularly preferably 10% by mass or less. If the content of monomer units other than ethylene units and propylene units is within such a range, the properties of the polyolefin such as water resistance, chemical resistance, and durability are improved, and polyolefins can be produced at low cost.
• Manufacturing methods for polyolefins include known manufacturing methods that use polymerization catalysts.
• polymerization catalysts include Ziegler catalysts or metallocene catalysts, and examples of polymerization methods include slurry polymerization and gas phase polymerization.
• Impact-resistant polypropylene also known as polypropylene block polymer, is essentially a mixture of polypropylene and a propylene-ethylene random copolymer, and can be manufactured by a process consisting of a first step of obtaining a propylene homopolymer and a second step of obtaining a propylene-ethylene random copolymer.
• the weight average molecular weight (Mw) of the acid-modified polyolefin contained in the adhesive layer is preferably 50,000 to 1,000,000, more preferably 100,000 to 750,000, and even more preferably 150,000 to 500,000.
• the melting point of the acid-modified polyolefin is preferably 130°C or higher, and more preferably 135°C or higher. If the melting point of the acid-modified polyolefin is within this range, the heat resistance of the adhesive layer and its adhesive strength at high temperatures can be improved.
• the melting point of the acid-modified polyolefin is preferably 160°C or less, and more preferably 150°C or less. When the melting point of the acid-modified polyolefin is within this range, good thermocompression bonding properties can be obtained, and the adhesive durability at low temperatures can be improved.
• the melt flow rate of the acid-modified polyolefin is preferably 3 g/10 min or more, more preferably 7 g/10 min or more.
• the melt flow rate of the acid-modified polyolefin is preferably 50 g/10 min or less, more preferably 30 g/10 min or less.
• the melt flow rate of the adhesive layer is a value measured in accordance with JIS K7210:2014 (ISO 1133 2011).
• the melt flow rate of the adhesive layer was measured at a resin temperature of 230°C and a load of 2.16 kg.
• the content of the acid-modified polyolefin in the adhesive layer may be 2% by mass or more.
• the acid-modified polyolefin may be used in a mixture with an unmodified polyolefin.
• a small amount of about 2% by mass of the acid-modified polyolefin may be used.
• the content of the acid-modified polyolefin in the adhesive layer is preferably 30% by mass or more, more preferably 70% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.
• a polymer other than the acid-modified polyolefin (hereinafter referred to as "other polymer C") can be added to the adhesive layer for the purpose of improving the adhesive strength at low temperatures, adhesive durability, molding stability, and adhesion to the base layer.
• other polymer C include styrene-based block copolymers such as styrene-butadiene-styrene block copolymers and hydrogenated products thereof, styrene-isoprene-styrene block copolymers and hydrogenated products thereof, and styrene-isobutylene-styrene block copolymers, as well as styrene-based graft copolymers in which a styrene homopolymer or copolymer is grafted onto a polyolefin.
• Unmodified polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymers may also be added as
• the lower limit of the content of other polymer C in the adhesive layer is preferably 1 mass% or more, more preferably 2 mass% or more, and particularly preferably 3 mass% or more. When the amount added is within this range, the improving effect of the other polymer C is enhanced.
• the upper limit of the content of other polymer C in the adhesive layer is preferably 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 10% by mass or less.
• the adhesive layer can obtain high heat resistance and high adhesive strength at high temperatures.
• an acid-modified polyolefin with a high degree of acid modification is used, the content of acid-modified polyolefin can be reduced. In such a case, the content of unmodified polyolefin may be high, and the upper limit of the content of unmodified polyolefin in the adhesive composition may be 98% by mass.
• a crosslinkable resin may be added to the adhesive layer, it is preferable that the content of the crosslinkable resin in the adhesive layer is small or not present at all.
• the content of the crosslinkable resin is small, the crystallinity of the acid-modified polyolefin increases, improving heat resistance and hydrolysis resistance.
• the content of the crosslinkable resin is small, it is possible to prevent the molecular weight from becoming excessively large due to crosslinking, and to improve the moldability of the adhesive layer.
• the content of the crosslinkable resin in the adhesive layer is preferably less than 3 mass%, more preferably less than 1 mass%, particularly preferably less than 0.5 mass%, and may be 0 mass%.
• the crosslinkable resin is capable of crosslinking the main component of the adhesive layer, and examples of such resins include resins having multiple functional groups such as phenol novolac-modified epoxy resin, oxazoline group-containing styrene resin, and epoxy group-containing polyolefin resin.
• the adhesive layer may further include an additive selected from the group consisting of antioxidants, UV absorbers, fillers, reinforcing fibers, release agents, processing aids, flame retardants, plasticizers, nucleating agents, antistatic agents, pigments, dyes, foaming agents, and combinations thereof.
• an additive selected from the group consisting of antioxidants, UV absorbers, fillers, reinforcing fibers, release agents, processing aids, flame retardants, plasticizers, nucleating agents, antistatic agents, pigments, dyes, foaming agents, and combinations thereof.
• the substrate layer preferably has a thickness in the range of 10 ⁇ m to 300 ⁇ m, more preferably in the range of 30 ⁇ m to 250 ⁇ m, and particularly preferably in the range of 50 ⁇ m to 200 ⁇ m.
• a thickness of the substrate layer is equal to or greater than this lower limit, sufficient rigidity is obtained.
• the thickness of the substrate layer is equal to or less than this upper limit, the effect on the thickness of an article incorporating the multilayer sheet, such as a battery, can be reduced.
• the primer layer preferably has a thickness in the range of 1 ⁇ m to 20 ⁇ m, more preferably in the range of 5 ⁇ m to 20 ⁇ m, and particularly preferably in the range of 10 ⁇ m to 20 ⁇ m.
• a thickness of the primer layer is equal to or greater than this lower limit, sufficient adhesion is obtained.
• the thickness of the primer layer is equal to or less than this upper limit, the effect on the thickness of the article incorporating the multilayer sheet, such as a battery, can be reduced.
• the adhesive layer preferably has a thickness in the range of 10 ⁇ m to 200 ⁇ m, more preferably in the range of 20 ⁇ m to 150 ⁇ m, and particularly preferably in the range of 30 ⁇ m to 100 ⁇ m.
• the thickness of the adhesive layer is equal to or greater than this lower limit, the occurrence of poor adhesion can be suppressed.
• the thickness of the adhesive layer is equal to or less than this upper limit, the adhesive can be prevented from spilling out of the multilayer sheet, and defects can be prevented in products incorporating the multilayer sheet, such as batteries.
• the multilayer sheet and the bonded body using the multilayer sheet can exhibit excellent adhesive performance, durability, productivity, and cost-effectiveness.
• the total thickness of the multilayer sheet is preferably 30 ⁇ m to 400 ⁇ m, more preferably 50 ⁇ m to 350 ⁇ m, and especially preferably 50 ⁇ m to 300 ⁇ m.
• the thickness of the multilayer sheet and each layer that constitutes the multilayer sheet is the arithmetic average of the thicknesses at three points measured by preparing a slice having a cross section perpendicular to the main surface of the multilayer sheet and measuring it using a VHS-8000 digital microscope (manufactured by Keyence Corporation).
• the base layer and adhesive layer are generally each manufactured from a resin composition as a raw material.
• the resin compositions that are the raw materials for the base layer and adhesive layer are compositions whose main component is resin and are made from the components of the base layer and adhesive layer described above.
• the resin composition that forms the base layer and adhesive layer can be produced by melt-kneading the main resin component and, if necessary, other components in an extruder, Banbury mixer, or heated roll, etc., and then cooling and solidifying the strands extruded from the nozzle holes of the die head while pulling them with water, etc., and cutting them into pellets.
• the temperature for melt-kneading the resin composition used in the base layer is preferably 150°C to 320°C, more preferably 180°C to 300°C, and the kneading time is usually 0.5 minutes to 20 minutes, preferably 1 minute to 15 minutes.
• the temperature for melt-kneading the resin composition used in the adhesive layer is preferably 150°C to 270°C, more preferably 170°C to 250°C, and the kneading time is usually 0.5 minutes to 20 minutes, preferably 1 minute to 15 minutes.
• the substrate layer and adhesive layer can be obtained by molding the resin composition used for the substrate layer and the resin composition used for the adhesive layer thus obtained into a film using a conventional method (e.g., extrusion molding).
• the primer layer is preferably formed on at least one side of the substrate layer by using a coating method. That is, the primer layer is preferably a coating layer.
• the primer layer can be formed by dissolving or dispersing the components of the primer layer described above in a solvent to prepare a primer layer-forming composition, coating the primer layer-forming composition on the substrate layer using a coating means, volatilizing the solvent to form a substrate layer with a coating film, bonding the substrate layer with the coating film obtained to an adhesive layer, and then curing the coating film.
• the solvent may be an organic solvent capable of dissolving or dispersing the components of the primer layer.
• a means for applying the primer layer-forming composition include a bar coater, a spray gun, a dispenser, a roll coater, a curtain coater, and a dip coater.
• the temperature and time for volatilizing the solvent can be set appropriately taking into consideration the type of solvent, etc., and can be, for example, 50°C to 200°C and 0.1 minutes to 5 minutes.
• the multilayer sheet according to the present disclosure can be produced as follows. First, the substrate layer with the coating film and the adhesive layer are each prepared in advance. Next, the surface of the substrate layer on which the coating film is disposed is placed opposite the adhesive layer, and a multi-layer laminate is obtained by thermal lamination. The laminate is then cured to harden the coating, yielding a multi-layer sheet.
• the thermal lamination can be carried out using a known laminator. There are no limitations on the lamination conditions, and general conditions can be applied.
• the lamination temperature is preferably from 50°C to 200°C, and more preferably from 80°C to 150°C.
• the transport speed during lamination is preferably 0.01 m/min to 200 m/min, and more preferably 0.1 m/min to 100 m/min.
• the lamination pressure is preferably from 0.01 MPa to 10 MPa, and more preferably from 0.1 MPa to 5 MPa.
• the coating hardens and a multilayer sheet is obtained in which the base layer, primer layer, and adhesive layer are more firmly bonded.
• the curing conditions are, for example, to leave the laminate at rest for 0.5 to 7 days at a temperature of 40°C to 150°C.
• the multilayer sheet according to the present disclosure can be bonded to an adherend formed of various materials such as metal, glass, ceramics, or plastic. This allows the production of an assembly including the multilayer sheet and the adherend.
• an assembly including the multilayer sheet can be used as a member or part of a layered battery.
• the multilayer sheet according to the present disclosure is preferably used as a gasket member for a fuel cell.
• the metal used as the adherend may be a commonly known metal plate, flat metal plate or metal foil, and iron, copper, aluminum, lead, zinc, titanium, chromium, stainless steel, etc. can be used. Among these, iron, aluminum, titanium and stainless steel are particularly preferred.
• thermoplastic or thermosetting resins can be used as the plastic to be used as the adherend.
• Composite materials in which inorganic materials such as glass or ceramics, or fillers or fibers such as metal or carbon are combined with resin can also be used.
• the multilayer sheet according to the present disclosure is not limited to the following examples.
• Substrate layer material Polyphenylsulfone film (PPSU): The PPSU film used was Radel R-5000 (manufactured by Solvay), and a film having a thickness of 70 ⁇ m was produced using a T-die extruder.
• PI Polyimide film
• PEN Polyethylene naphthalate film
• the PEN film used was Teonex Q51 (thickness: 100 ⁇ m, manufactured by Toyobo Co., Ltd.).
• Primer layer material ⁇ Acid-modified polyolefin-1 (PO-1) Propylene-butene-1 copolymer, melting point: 70°C, molecular weight: Mw 100,000, maleic anhydride modification rate: 1.1% by mass ⁇ Acid-modified polyolefin-2 (PO-2) Propylene-butene-1 copolymer, melting point 80°C, molecular weight Mw90,000, maleic anhydride modification rate 1.1% by mass ⁇ Polycarbonate diol-1 (PD-1) Duranol T5652 (manufactured by Asahi Kasei Corporation) ⁇ Polycarbonate diol-2 (PD-2) Duranol T5650J (manufactured by Asahi Kasei Corporation) ⁇ Polycarbonate diol-3 (PD-3) Duranol T3452 (manufactured by Asahi Kasei Corporation)
• ⁇ Curing Agent> ⁇ Isocyanate compound-1 Duranate TPA-100 (manufactured by Asahi Kasei Corporation) Epoxy compound-1 EPICLON HP-7200 (DIC Corporation)
• Adhesive layer material TM55 (Aronmelt (registered trademark) TM55, melting point 142° C., manufactured by Toagosei Co., Ltd.) was used to prepare a film having a thickness of 55 ⁇ m using a T-die extruder.
• Substrate layer Both sides of the substrate were treated with a corona treatment machine (Navidas, Polydyne 1, discharge amount: 81.5 W ⁇ min/m 2 , one round trip).
• Adhesive layer One side (only the surface to be bonded to the primer layer) was treated with a corona treatment machine (Navidas, Polydyne 1, discharge amount: 81.5 W ⁇ min/m 2 , one round trip).
• compositions for forming a primer layer As compositions for forming a primer layer, primer 1 (P-1) to primer 7 (P-7) were prepared as follows.
• Primer 1 (P-1) 14.9 g of acid-modified polyolefin (PO-1) was dissolved in a mixed solvent of 36.2 g of methyl ethyl ketone and 50.8 g of methylcyclohexane at 60° C. under heating, and then 0.3 g of dioctyl tin laurate, 2.4 g of isocyanate compound-1, and 2.4 g of isocyanate compound-2 were dissolved therein to obtain primer 1 (PO-1).
• Primer 2 (P-2) 20.0 g of acid-modified polyolefin (PO-2) was dissolved in a mixed solvent of 35.5 g of toluene, 8.3 g of methyl ethyl ketone, and 82.9 g of methylcyclohexane at 60° C. under heating, and then 2.0 g of epoxy compound-1 and 0.03 g of imidazole compound-1 were dissolved therein to obtain primer 2 (PO-2).
• PO-2 acid-modified polyolefin
• Primer 3 50.0 g of polycarbonate diol-1 (PD-1) was dissolved in a mixed solvent of 50.0 g of toluene and 5.0 g of methyl ethyl ketone, and then 10.0 g of isocyanate compound-1 was dissolved therein to obtain primer 3 (P-3).
• Primer 4 (P-4) 67.0 g of polycarbonate diol-2 (PD-2) was dissolved in a mixed solvent of 33.0 g of toluene and 14.9 g of methyl ethyl ketone, and then 30.1 g of isocyanate compound-1 was dissolved therein to obtain Primer 4 (P-4).
• Primer 5 50.0 g of polycarbonate diol-3 (PD-3) was dissolved in a mixed solvent of 50.0 g of toluene and 5.0 g of methyl ethyl ketone, and then 10.0 g of isocyanate compound-1 was dissolved therein to obtain primer 5 (P-5).
• compositions of primer 1 (P-1) to primer 5 (P-5) are summarized in Table 1 below.
• P-1 to P-5 correspond to primer 1 (P-1) to primer 5 (P-5), respectively.
• the unit of composition is "g.”
• Primer 6 (P-6) As a two-component urethane adhesive, Takelac A-1143 (polyester polyol; manufactured by Mitsui Chemicals, Inc.) and Takenate A-3 (aromatic isocyanate; manufactured by Mitsui Chemicals, Inc.) were mixed in a mass ratio of 9:1 to obtain Primer 6 (P-6), which is a two-component urethane adhesive.
• Example 1 Primer 1 (P-1) was applied to one side of a polyphenylsulfone film (PPSU, thickness 70 ⁇ m) with a bar coater to a coating thickness of 10 ⁇ m (dry), and the solvent was evaporated at 100° C. for 1 minute to obtain a coated film (coated substrate layer). Thereafter, the coating surface of the obtained coated film was bonded to TM55 (acid-modified polypropylene film; thickness 55 ⁇ m) by thermal lamination (100° C., 0.3 m/min, 0.3 MPa). Primer 1 (P-1) was also applied to the uncoated side of the PPSU film in the same manner, and the film was bonded to TM55 to obtain a laminate.
• PPSU polyphenylsulfone film
• TM55 acid-modified polypropylene film
• the obtained laminate was then aged at 100° C. for 4 days to harden the coating.
• a multilayer sheet (thickness 200 ⁇ m) was obtained in which the adhesive layer (thickness 55 ⁇ m) / primer layer (thickness 10 ⁇ m) / base layer (thickness 70 ⁇ m) / primer layer (thickness 10 ⁇ m) / adhesive layer (thickness 55 ⁇ m) were laminated in this order.
• Example 2 Primer 2 (P-2) was applied to one side of a polyphenylsulfone film (PPSU, thickness 70 ⁇ m) with a bar coater to a coating thickness of 10 ⁇ m (dry), and the solvent was evaporated at 100° C. for 1 minute to obtain a coated film (coated substrate layer). The coating surface of the obtained coated film was then bonded to TM55 (acid-modified polypropylene film; thickness 55 ⁇ m) by thermal lamination (100° C., 0.3 m/min, 0.3 MPa). Primer 2 (P-2) was also applied to the uncoated side of the PPSU film in the same manner, and the film was bonded to TM55 to obtain a laminate.
• PPSU polyphenylsulfone film
• TM55 acid-modified polypropylene film
• the resulting laminate was then aged at 80°C for 2 days to harden the coating, thereby obtaining a multilayer sheet (thickness 200 ⁇ m) in which an adhesive layer (thickness 55 ⁇ m)/primer layer (thickness 10 ⁇ m)/substrate layer (thickness 70 ⁇ m)/primer layer (thickness 10 ⁇ m)/adhesive layer (thickness 55 ⁇ m) were laminated in that order.
• Example 3 Primer 1 (P-1) was applied to one side of a polyimide film (PI, thickness 125 ⁇ m) with a bar coater to a coating thickness of 10 ⁇ m (dry), and the solvent was evaporated at 100° C. for 1 minute to obtain a coated film (coated substrate layer). Thereafter, the coating surface of the obtained coated film was bonded to TM55 (acid-modified polypropylene film; thickness 55 ⁇ m) by thermal lamination (100° C., 0.3 m/min, 0.3 MPa). Primer 1 (P-1) was also applied to the uncoated side of the PI film in the same manner, and the laminate was obtained by bonding with TM55.
• TM55 acid-modified polypropylene film
• the resulting laminate was then aged at 100°C for 4 days to harden the coating, thereby obtaining a multilayer sheet (thickness 255 ⁇ m) in which an adhesive layer (thickness 55 ⁇ m)/primer layer (thickness 10 ⁇ m)/substrate layer (thickness 125 ⁇ m)/primer layer (thickness 10 ⁇ m)/adhesive layer (thickness 55 ⁇ m) were laminated in that order.
• Example 4 Primer 2 (P-2) was applied to one side of a polyimide film (PI, thickness 125 ⁇ m) with a bar coater to a coating thickness of 10 ⁇ m (dry), and the solvent was evaporated at 100° C. for 1 minute to obtain a coated film (coated substrate layer). Thereafter, the coating surface of the obtained coated film was bonded to TM55 (acid-modified polypropylene film; thickness 55 ⁇ m) by thermal lamination (100° C., 0.3 m/min, 0.3 MPa). Primer 2 (P-2) was also applied to the uncoated side of the PI film in the same manner, and the laminate was obtained by bonding with TM55.
• TM55 acid-modified polypropylene film
• the resulting laminate was then cured at 80°C for 2 days to harden the coating, thereby obtaining a multilayer sheet (thickness 255 ⁇ m) in which an adhesive layer (thickness 55 ⁇ m)/primer layer (thickness 10 ⁇ m)/substrate layer (thickness 125 ⁇ m)/primer layer (thickness 10 ⁇ m)/adhesive layer (thickness 55 ⁇ m) were laminated in that order.
• Primer 3 (P-3) was applied to one side of a polyphenylsulfone film (PPSU, thickness 70 ⁇ m) with a bar coater to a coating thickness of 10 ⁇ m (dry), and the solvent was evaporated at 100° C. for 1 minute to obtain a coated film. Thereafter, the coating surface of the obtained coated film was bonded to TM55 (acid-modified polypropylene film; thickness 55 ⁇ m) by lamination (roll normal temperature, 0.3 m/min, 0.3 MPa). Primer 3 (P-3) was also applied to the uncoated side of the PPSU film in the same manner, and the laminate was bonded to TM55 to obtain a laminate.
• TM55 acid-modified polypropylene film
• the resulting laminate was then aged at 60°C for 2 days to harden the coating, thereby obtaining a multilayer sheet (thickness 200 ⁇ m) in which an adhesive layer (thickness 55 ⁇ m)/primer layer (thickness 10 ⁇ m)/substrate layer (thickness 70 ⁇ m)/primer layer (thickness 10 ⁇ m)/adhesive layer (thickness 55 ⁇ m) were laminated in that order.
• Comparative Example 2 A multilayer sheet (thickness 200 ⁇ m) was obtained in the same manner as in Comparative Example 1, except that "Primer 4 (P-4)" was used instead of "Primer 3 (P-3)" as the resin composition forming the primer layer.
• the multilayer sheet (thickness 200 ⁇ m) was laminated in the following order: adhesive layer (thickness 55 ⁇ m) / primer layer (thickness 10 ⁇ m) / base layer (thickness 70 ⁇ m) / primer layer (thickness 10 ⁇ m) / adhesive layer (thickness 55 ⁇ m).
• Primer 3 (P-3) was applied to one side of a polyimide film (PI, thickness 125 ⁇ m) with a bar coater to a coating thickness of 10 ⁇ m (dry), and the solvent was evaporated at 100° C. for 1 minute to obtain a coated film (coated substrate layer). Thereafter, the coating surface of the obtained coated film was bonded to TM55 (acid-modified polypropylene film; thickness 55 ⁇ m) by lamination (roll normal temperature, 0.3 m/min, 0.3 MPa). Primer 3 (P-3) was also applied to the uncoated side of the PI film in the same manner, and the laminate was bonded to TM55 to obtain a laminate.
• TM55 acid-modified polypropylene film
• the resulting laminate was then cured at 60°C for 2 days to harden the coating, thereby obtaining a multilayer sheet (thickness 255 ⁇ m) in which an adhesive layer (thickness 55 ⁇ m)/primer layer (thickness 10 ⁇ m)/substrate layer (thickness 125 ⁇ m)/primer layer (thickness 10 ⁇ m)/adhesive layer (thickness 55 ⁇ m) were laminated in that order.
• Primer 2 (P-2) was applied to one side of a polyethylene naphthalate (PEN) film (thickness 100 ⁇ m) with a bar coater to a coating thickness of 10 ⁇ m (dry), and the solvent was evaporated at 100° C. for 1 minute to obtain a coated film. Thereafter, the coating surface of the obtained coated film was bonded to TM55 (acid-modified polypropylene film; thickness 55 ⁇ m) by lamination (roll normal temperature, 0.3 m/min, 0.3 MPa). Primer 3 (P-3) was similarly applied to the uncoated side of the PEN film, and the film was bonded to TM55 to obtain a laminate.
• TM55 acid-modified polypropylene film
• the resulting laminate was then aged at 80°C for 2 days to harden the coating, thereby obtaining a multilayer sheet (thickness 230 ⁇ m) in which an adhesive layer (thickness 55 ⁇ m)/primer layer (thickness 10 ⁇ m)/substrate layer (thickness 100 ⁇ m)/primer layer (thickness 10 ⁇ m)/adhesive layer (thickness 55 ⁇ m) were laminated in that order.
• the initial peel strength was measured by the hot water peel test described below.
• a SUS304 plate having a thickness of 0.1 mm was used as an adherend, and the multilayer sheet produced in the examples and comparative examples was sandwiched between the SUS304 plates and heat-pressed (180°C, 3 seconds, 1 MPa) with a precision press to produce a bonded body.
• This bonded body was cut into a strip of 10 mm width to prepare a test piece.
• the bonded part of the test piece was 10 mm wide and 15 mm long.
• P-1 to P-7 correspond to primer 1 (P-1) to primer 7 (P-7), respectively.
• the multilayer sheet of the embodiment in which the base layer contains a specific polymer and the primer layer contains an acid-modified polyolefin has superior adhesion durability in high temperature and moisture environments compared to the comparative example in which the primer layer does not contain an acid-modified polyolefin.
• the multilayer sheet according to the present disclosure is useful for bonding and sealing metals and other materials, and can be suitably used in applications where the resulting bonded body may come into contact with moisture continuously or intermittently.
• the multilayer sheet according to the present disclosure has excellent adhesive durability even in high temperature and moisture-containing environments, and therefore has a wide range of applications.
• Multilayer sheets according to the present disclosure include, for example, electric wires and cables in which metal conductors or optical fibers are covered with resin molded products, automotive mechanical parts, automotive exterior parts, automotive interior parts, molded power supply substrates, light reflectors for reflecting light sources, fuel cases for solid methanol batteries, insulation for metal pipes, insulation for vehicles, fuel cell water pipes, decorative molded products, water cooling tanks, boiler exterior cases, peripheral parts and components for printer ink, water piping, joints, secondary battery alkaline storage battery tanks, gasket seal materials for various layered batteries, etc.

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