WO2024135571A1

WO2024135571A1 - Multilayer sheet

Info

Publication number: WO2024135571A1
Application number: PCT/JP2023/045113
Authority: WO
Inventors: 圭悟岩槻; 雄希宮澤; 隆行尾鍋
Original assignee: 東亞合成株式会社
Priority date: 2022-12-20
Filing date: 2023-12-15
Publication date: 2024-06-27

Abstract

A multilayer sheet according to the present invention is characterized by: comprising a substrate layer (A) containing a polyphenylene ether, and an adhesive agent layer (B) containing an acid-modified polyolefin; and further comprising, between the substrate layer (A) and the adhesive layer (B), a tie layer (C) containing a styrene-based elastomer, a polyphenylene ether, and a polyolefin.

Description

Multi-layer sheet

The present invention relates to a multilayer sheet with excellent adhesiveness and heat resistance that can be used to bond or seal various parts and can be used as a sheet-like member by itself, and a base sheet that is a manufacturing material for the multilayer sheet.

In recent years, 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.

For battery applications, hot melt adhesive compositions are required to have durability against the constituent materials of the battery in addition to adhesive strength. In lithium ion batteries, lithium hexafluorophosphate used as an electrolyte may react with moisture to generate hydrofluoric acid, and in fuel cells, acids such as hydrofluoric acid may be generated from the electrolyte membrane, which is a constituent material of the battery, so acid resistance is required. Furthermore, in lithium ion batteries, durability against ethylene carbonate or diethyl carbonate used as a solvent for the electrolyte is required, and in nickel-metal hydride batteries, durability against strong alkaline aqueous solutions is required. In addition, in fuel cells, a coolant containing ethylene glycol or propylene glycol is circulated inside the battery to cool the battery that generates heat due to power generation, so durability against the ethylene glycol, etc. is also required.

Patent Document 1 discloses a resin composition consisting of 50-99% by mass of a low-viscosity propylene-based base polymer that satisfies specific properties and 1-50% by mass of an acid-modified propylene-based elastomer that satisfies specific properties, as well as a hot melt adhesive that contains said resin composition. This has excellent adhesion to polyolefin-based substrates and also has excellent adhesion to metal substrates. Patent Document 2 describes acid-modified polypropylene as an adhesive between metal and nylon-based resin.

By laminating an acid-modified polyolefin adhesive film or sheet onto a substrate layer to form a multilayer sheet, it is possible to obtain an adhesive member with even higher performance and functionality. Engineering plastics with excellent rigidity and heat resistance are used for the substrate layer of this multilayer sheet. By forming the acid-modified polyolefin adhesive into such a multilayer sheet, the strength, rigidity, gas barrier properties, chemical resistance, acid and alkali resistance, heat resistance, etc. are improved, making it suitable for use in applications requiring these durability, such as the lithium ion batteries and fuel cells mentioned above. In addition, by using the multilayer sheet as an adhesive member for lithium ion batteries and fuel cells, it is possible to reduce the number of constituent materials and parts, which also enables cost reduction and productivity improvement.

In terms of heat resistance, rigidity, dimensional stability, and cost, engineering plastics used as the base material of multilayer sheets have included polyethylene naphthalate, heat-resistant polyolefins such as cycloolefin polymers, polyphenylene ether alloys, and aromatic polyamide resins. For example, Patent Document 3 describes a laminate sheet for sealing electronic devices in which a first sheet and a second sheet are laminated, the first sheet containing an acid-modified polyolefin thermoplastic resin, the second sheet having a higher melting point than the first sheet, and the peel strength of the second sheet against the first sheet at 25°C being 0.5 to 10.0 [N/15 mm]. Patent Document 3 describes polyethylene naphthalate as a specific example of the second sheet.

JP 2013-060521 A JP 2017-109613 A International Publication No. 2011/013389

As mentioned above, a multilayer sheet made by laminating an adhesive layer containing acid-modified polyolefin and a base layer containing heat-resistant polyolefins such as polyethylene naphthalate and cycloolefin polymers, and engineering plastics such as polyphenylene ether and aromatic polyamide resins, is used as an adhesive member. However, polyethylene naphthalate and aromatic polyamide resins undergo hydrolysis during long-term use, and there are problems with their durability in environments where they come into contact with moisture. Cycloolefin polymers have a problem in that their softening point is not high enough, limiting the bonding temperature. Cycloolefin polymers also have low toughness, making them prone to problems such as cracking after long-term use.

Although polyphenylene ether does not have the problems of deterioration over long-term use seen with other engineering plastics, it does have the serious problem of not adhering to the acid-modified polyolefin used in the adhesive layer, and easily undergoing interlayer delamination.

The problem that the present invention aims to solve is to provide a multilayer sheet that includes an adhesive layer containing an acid-modified polyolefin and a base layer containing polyphenylene ether, the multilayer sheet having high interlayer peel strength. Another problem that the present invention aims to solve is to provide a base sheet containing polyphenylene ether that can be firmly adhered to an adhesive containing an acid-modified polyolefin.

The inventors conducted extensive research to solve the above problems when developing a multilayer sheet containing an adhesive layer containing an acid-modified polyolefin and a substrate layer containing polyphenylene ether. Specifically, they searched for various resin materials with the idea of providing a new tie layer with excellent adhesive strength between the adhesive layer containing an acid-modified polyolefin and the substrate layer containing polyphenylene ether, and discovered a resin composition suitable for the tie layer, thus completing the present invention.

Means for solving the above problems include the following aspects.
[1] A multilayer sheet comprising a substrate layer (A) containing a polyphenylene ether and an adhesive layer (B) containing an acid-modified polyolefin, and further comprising a tie layer (C) between the substrate layer (A) and the adhesive layer (B) containing a styrene-based elastomer, a polyphenylene ether, and a polyolefin.
[2] The multilayer sheet according to [1], wherein the styrene-based elastomer is selected from the group consisting of a styrene-diene block copolymer, a hydrogenated styrene-diene block copolymer, a modified styrene-diene block copolymer, a modified hydrogenated styrene-diene block copolymer, and combinations thereof.
[3] The multilayer sheet according to [1] or [2], wherein the styrene-based elastomer comprises a modified product of a hydrogenated styrene-diene block copolymer, and the modified product of the hydrogenated styrene-diene block copolymer has a functional group selected from the group consisting of a carboxylic acid group, a carboxylic anhydride group, an epoxy group, an amino group, and combinations thereof.
[4] The multilayer sheet according to any one of [1] to [3], wherein the polyolefin of the tie layer (C) is polypropylene.
[5] The multilayer sheet according to any one of [1] to [4], wherein the polyolefin of the tie layer (C) is a metallocene-based polypropylene.
[6] The multilayer sheet according to any one of [1] to [5], wherein in the tie layer (C), a mass ratio of the styrene-based elastomer to the polyphenylene ether is 30/70 to 80/20.
[7] The multilayer sheet according to any one of [1] to [6], wherein in the tie layer (C), a mass ratio of the total amount of the styrene-based elastomer and the polyphenylene ether to the polyolefin is 50/50 to 85/15.
[8] The multilayer sheet according to any one of [1] to [7], wherein the softening point of the base layer (A) is 175° C. or higher.
[9] The multilayer sheet according to any one of [1] to [8], wherein the storage modulus of the base layer (A) at 160° C. is 500 MPa or more.
[10] The multilayer sheet according to any one of [1] to [9], wherein the acid-modified polyolefin is a maleic anhydride-modified polyolefin.
[11] The multilayer sheet according to any one of [1] to [10], wherein the base layer (A) has a thickness of 50 to 300 μm, the adhesive layer (B) has a thickness of 10 to 100 μm, and the tie layer (C) has a thickness of 2 to 50 μm.
[12] A substrate sheet comprising a substrate layer (A) containing polyphenylene ether, and a tie layer (C) containing a styrene-based elastomer, polyphenylene ether, and a polyolefin.
[13] The base sheet according to [12], wherein in the tie layer (C), a mass ratio of the styrene-based elastomer to the polyphenylene ether is 30/70 to 80/20.
[14] The base sheet according to [12] or [13], wherein in the tie layer (C), a mass ratio of the total amount of the styrene-based elastomer and the polyphenylene ether to the polyolefin is 50/50 to 85/15.
[15] A method for producing a multilayer sheet, comprising: preparing a base sheet comprising a base layer (A) containing polyphenylene ether and a tie layer (C) containing a styrene-based elastomer, polyphenylene ether, and a polyolefin; and laminating an adhesive layer (B) containing an acid-modified polyolefin on the tie layer (C).

According to one embodiment of the present invention, a multilayer sheet can be provided that includes an adhesive layer containing an acid-modified polyolefin and a base layer containing polyphenylene ether, and that has high interlayer peel strength. Also, according to one embodiment of the present invention, a base sheet can be provided that includes polyphenylene ether and can be firmly adhered to an adhesive containing an acid-modified polyolefin.

By providing a tie layer between the adhesive layer and the base layer, whose main components are styrene-based elastomer, polyphenylene ether, and polyolefin, the interface between the adhesive layer and the base layer can be firmly bonded, producing a multi-layer sheet with excellent adhesion and heat resistance. This makes it possible to provide high-performance, economical sheet-type battery components, etc.

The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, the word "~" is used to mean that the numerical values before and after it are included as the lower and upper limits.

In the numerical ranges described in this specification in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in this specification, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples.

The multilayer sheet of the present invention comprises a substrate layer (A) containing polyphenylene ether and an adhesive layer (B) containing an acid-modified polyolefin, and further comprises a tie layer (C) containing a styrene-based elastomer, polyphenylene ether and polyolefin between the substrate layer (A) and the adhesive layer (B). The tie layer is a layer disposed between the substrate layer and the adhesive layer, firmly bonding them together and increasing the peel strength of the multilayer sheet. Typical layer configurations of the multilayer sheet include a three-layer sheet of substrate layer (A)/tie layer (C)/adhesive layer (B) and a five-layer sheet of adhesive layer (B)/tie layer (C)/substrate layer (A)/tie layer (C)/adhesive layer (B).

The substrate sheet of the present invention has a substrate layer (A) containing polyphenylene ether and a tie layer (C) containing a styrene-based elastomer, polyphenylene ether, and a polyolefin. Typical layer configurations of the substrate sheet include a two-layer sheet of substrate layer (A)/tie layer (C) and a three-layer sheet of tie layer (C)/substrate layer (A)/tie layer (C). The above multilayer sheet can be produced using the substrate sheet.

The substrate layer (A) contains polyphenylene ether. Polyphenylene ether is typically a homopolymer or copolymer containing monomer units represented by the following formula:

In the formula, R ₁ to R ₄ are selected from a hydrogen atom, a halogen atom, a primary or secondary alkyl group, an aryl group, an aminoalkyl group, a haloalkyl group, an alkoxy group and a haloalkoxy group, R ₁ and R ₃ are preferably hydrogen atoms, and R ₂ and R ₄ are preferably methyl groups.

Representative examples of polyphenylene ether homopolymers include poly(2,6-dimethyl-1,4-phenylene) ether, poly(2-methyl-6-ethyl-14-phenylene) ether, poly(2,6-diethyl-1,4-phenylene) ether, poly(2-ethyl-6-n-propyl-1,4-phenylene) ether, poly(2,6-di-n-propyl-1,4-phenylene) ether, poly(2-methyl-6-n-butyl-1,4-phenylene) ether, poly(2-ethyl-6-isopropyl-1,4-phenylene) ether, poly(2-methyl-6-chloroethyl-1,4-phenylene) ether, poly(2-methyl-6-hydroxyethyl-1,4-phenylene) ether, and poly(2-methyl-6-chloroethyl-1,4-phenylene) ether.
Representative examples of polyphenylene ether copolymers include a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol, a copolymer of 2,6-dimethylphenol and o-cresol, and a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol and o-cresol.
Among the polyphenylene ethers, poly(2,6-dimethyl-1,4-phenylene) ether is preferred.

Polyphenylene ether can be produced by a known method. For example, it can be polymerized using a metal catalyst such as copper. Specifically, it can be produced in accordance with the method for producing polyphenylene ether described in the examples of International Publication WO2012/046308 and the like.
In addition, it is also available as a commercial material, and NORYL manufactured by SAIBC or the like can be suitably used.

The mass ratio of polyphenylene ether in the base layer (A) is preferably 50 mass% or more, more preferably 60 mass% or more, particularly preferably 70 mass% or more, and may be 100 mass%. When the mass ratio of polyphenylene ether in the base layer (A) is within such a range, the heat resistance of the multilayer sheet can be improved. There is no particular upper limit to the mass ratio of polyphenylene ether in the base layer (A), but for example, when a polymer other than polyphenylene ether is used in the base layer (A), the mass ratio of polyphenylene ether in the base layer (A) is preferably 99.9 mass% or less, more preferably 98 mass% or less, particularly preferably 95 mass% or less. When the mass ratio of polyphenylene ether is within such a range, the moldability of the multilayer sheet can be improved.

The substrate layer (A) may optionally contain a polystyrene component selected from the group consisting of polystyrene, styrene-based elastomers, and combinations thereof.

Typical polystyrenes are general-purpose polystyrene (GPPS), which is a polymer of styrene alone, and high impact polystyrene (HIPS), which is GPPS with added rubber to give it impact resistance, but copolymers of styrene and acrylonitrile or (meth)acrylic acid esters can also be used.

Examples of styrene-based elastomers include styrene-butadiene binary block copolymers, styrene-butadiene-styrene ternary block copolymers, styrene-isoprene binary block copolymers, styrene-isoprene-styrene ternary block copolymers, and hydrogenated products thereof. These block copolymers and graft copolymers may be modified with an acid such as maleic anhydride, epoxy modified with an oxidizing agent, or terminal amine modified to provide functional groups such as carboxylic acid groups, carboxylic anhydride groups, epoxy groups, and amino groups. These functional groups may be effective in improving the interfacial adhesion with the tie layer (C). The inclusion of these components improves toughness and molding stability at low temperatures.

The total amount of polyphenylene ether, polystyrene, and styrene-based elastomer in the base layer (A) is preferably 60% by mass or more, and more preferably 70% by mass or more. There is no particular upper limit to the total amount of polyphenylene ether, polystyrene, and styrene-based elastomer in the base layer (A), but in one embodiment of the present invention, the total amount of polyphenylene ether, polystyrene, and styrene-based elastomer in the base layer (A) 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 softening point of the base layer (A) is preferably 175°C or higher, more preferably 180°C or higher, and particularly preferably 185°C or higher. Having a softening point within this range improves the heat resistance of the multilayer sheet.

The storage modulus of the base layer (A) 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 (A) 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 of the multilayer sheet due to thermocompression during adhesion can be prevented.

The softening point and storage modulus in this invention are values determined using a tensile viscoelasticity device (DMS6100 manufactured by Hitachi High-Tech Sanence Corporation). Specifically, the temperature is raised 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 δ with temperature are recorded. The softening point in this invention refers to the temperature at which tan δ is at its maximum.

In terms of heat resistance, the creep rate of the base layer (A) in a compression creep test is preferably 30% or less, and more preferably 25% or less. The creep rate is measured according to the method described in the examples shown below.

In terms of heat resistance, the thermal deformation rate of the base layer (A) in a heat shrinkage test is preferably 0.50% or less, and more preferably 0.30% or less. The thermal deformation rate is measured according to the method described in the examples shown below.

The melt flow rate of the base layer (A) is preferably 1 g/10 min or more, more preferably 2 g/10 min or more. The melt flow rate of the base layer (A) is preferably 50 g/10 min or less, more preferably 30 g/10 min or less. When the melt flow rate of the base layer (A) is equal to or higher than the lower limit, the material strength is improved. When the melt flow rate of the base layer (A) is equal to or lower than the upper limit, the fluidity is improved and the moldability is improved.

Here, the melt flow rate is a value measured in accordance with JIS K7210:2014. The melt flow rate of the base layer (A) was measured at a resin temperature of 300°C and a load of 2.16 kg.

The base layer (A) may contain, in addition to the above composition, polymers other than polyphenylene ether, polystyrene, and styrene-based elastomers (hereinafter referred to as other polymers (A)) to the extent that the characteristics of the present invention are not impaired. Examples of other polymers (A) include ethylene homopolymers, metal neutralized products of ethylene-acrylic acid copolymers and ethylene-methacrylic acid copolymers, ethylene-butyl acrylate copolymers, propylene homopolymers, propylene-α-olefin copolymers, butene homopolymers, polyamide-based resins such as nylon 6 and nylon 66, and other resins. These may be used alone or in combination of two or more. The base layer (A) may further contain additives selected from the group consisting of antioxidants, ultraviolet 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 (B) contains an acid-modified polyolefin. The acid-modified polyolefin is an unmodified polyolefin (hereinafter also simply referred to as "polyolefin") that has been graft-modified with an acid compound selected from the group consisting of unsaturated carboxylic acids, unsaturated carboxylic anhydrides, and combinations thereof.

Examples of monomer units constituting polyolefins include monomer units derived from monomers selected from the group consisting of α-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.

Among these, polyolefins selected from the group consisting of polyethylene, polypropylene, polymer blends of polyethylene and polypropylene, ethylene-propylene copolymers, copolymers of the above-mentioned monomer units with one or more monomers selected from 1-octene, vinyl acetate, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, glycidyl (meth)acrylate, (meth)acrylic acid, metal neutralized (meth)acrylic acid, maleic anhydride, and vinyl silanes, and combinations thereof, are preferred because they have high adhesive strength to the substrate.

Polyethylene is a polymer containing ethylene units as the main component, and may be either a homopolymer or a copolymer. When it 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 it is a copolymer, the content of propylene units in the polypropylene is preferably 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.

In addition to physical blends consisting of multiple components of these resins, polyolefins also include reactive blends in which functional groups are reacted between different polymers in a molding machine, graft copolymers and block copolymers consisting of multiple segments, and compositions in which physical blends using these as compatibilizers are microdispersed.

In all monomer units contained in the polyolefin, 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.

　Manufacturing methods for polyolefins include known manufacturing methods that use polymerization catalysts. Polymerization catalysts include Ziegler catalysts and metallocene catalysts, and 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 acid compound used in producing the acid-modified polyolefin is selected from the group consisting of unsaturated carboxylic acids, unsaturated carboxylic anhydrides, and combinations thereof.

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.

Specific examples of unsaturated monocarboxylic acids include acrylic acid, methacrylic acid, crotonic acid, and isocrotonic acid.

Specific examples of unsaturated dicarboxylic acids include maleic acid, fumaric acid, itaconic acid, citraconic acid, nadic acid, and endic acid.

Unsaturated carboxylic acid anhydrides are compounds that have an ethylenic double bond and a carboxylic acid anhydride group in the same molecule, and examples thereof include the acid anhydrides of the unsaturated dicarboxylic acids mentioned above. Specific examples of acid anhydrides of unsaturated dicarboxylic acids include maleic anhydride, fumaric anhydride, itaconic anhydride, citraconic anhydride, nadic anhydride, and endic anhydride.

Among these, maleic acid and maleic anhydride are preferably used because of their high modifying effect, with maleic anhydride being particularly preferred.

The method of modifying a polyolefin with an acid compound is not particularly limited, and examples of the method include a solution modification method in which an acid compound and a radical generator are added to a solution in which the polyolefin is dissolved in an organic solvent, and the solution is reacted at a temperature of usually 60 to 350°C, preferably 80 to 190°C, for usually 0.5 to 15 hours, preferably 1 to 10 hours, or a melt modification method in which the polyolefin and the acid compound are melted at a temperature above the melting point of the polyolefin, for example 170 to 280°C, using an extruder or the like, and reacted for usually about 0.5 to 10 minutes. Whichever modification method is used, it is preferable to carry out the reaction in the presence of a radical generator in order to efficiently react the acid compound for modification.

The radical generator to be used may be selected from commercially available organic peroxides, taking into consideration the reaction temperature, etc.

If some of the acid compound used in the graft modification remains unreacted, it is preferable to remove the unreacted acid compound by a known method such as vacuum distillation in order to prevent adverse effects on the adhesive strength.

The graft amount of the acid compound is preferably 0.01 mass% or more, more preferably 0.4 mass% or more, and particularly preferably 0.6 mass% or more. When the graft amount is within this range, the adhesiveness of the adhesive layer (B) can be improved.

The graft amount of the acid compound is preferably 5% by mass or less, more preferably 2% by mass or less, and particularly preferably 1% by mass or less. If the graft amount is within this range, it is possible to suppress the appearance of the product due to fish eyes, bumps, etc. during molding, and also to improve adhesion.

In this specification, the graft amount means the amount of an acid compound introduced by graft copolymerization to the main chain of an unmodified polyolefin. The graft amount can be calculated from the acid value of the acid-modified polyolefin by the following formula:
Graft amount (mass%)=acid value×M×100/(1000×56.1×V)
In the formula, M and V are defined as follows:
M = (molecular weight of acid compound) + (number of unsaturated groups in acid compound) x 1.008
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 acid-modified polyolefin, and is measured in accordance with JIS K 0070:1992.

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 and adhesive strength at high temperatures of the adhesive layer (B) 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.

In the present invention, the melting point refers to the temperature at the top of the endothermic peak that occurs when a differential scanning calorimeter (DSC) is used, the temperature is first held at 180°C for several minutes, then cooled to 0°C at a rate of 10°C per minute, and then heated to 200°C at a rate of 10°C per minute.

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.

In the present invention, the melt flow rate is a value measured in accordance with JIS K7210:2014. The melt flow rate of the adhesive layer (B) 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 (B) may be 2% by mass or more. For example, the acid-modified polyolefin may be used in a mixture with an unmodified polyolefin, and when an acid-modified polyolefin with a high degree of acid modification is used, a small amount of about 2% by mass may be used. The content of the acid-modified polyolefin in the adhesive layer (B) is not particularly limited, and may be a high content of, for example, 50% by mass or more.

In order to improve the adhesive strength at low temperatures, adhesive durability, and molding stability, and to improve adhesion to the tie layer (C), a polymer other than the acid-modified polyolefin (hereinafter referred to as "other polymer (B)") can be added to the adhesive layer (B). Examples of other polymers (B) include unmodified polyolefins such as polyethylene, polypropylene, and ethylene-α-olefin copolymers, styrene-butadiene-styrene block copolymers and their hydrogenated products, styrene-isoprene-styrene block copolymers and their hydrogenated products, styrene-isobutylene-styrene block copolymers, styrene-based graft copolymers in which styrene homopolymers or copolymers are grafted to polyolefins, and polyamide resins such as nylon 6 and nylon 66.

When the other polymer (B) is used, the lower limit of the content of the other polymer (B) in the adhesive layer (B) is preferably 1% by mass or more, more preferably 2% by mass or more, and particularly preferably 3% by mass or more. When the amount added is within this range, the improving effect of the other polymer (B) is enhanced.

When using other polymers (B), the content of other polymers (B) in the adhesive layer (B) is not limited as long as the adhesive performance is not reduced. As described above, when using an acid-modified polyolefin with a high degree of acid modification, the content of the acid-modified polyolefin can be reduced. In such a case, the content of unmodified polyolefin may be high, and the content of unmodified polyolefin in the adhesive layer (B) may be, for example, 50% by mass or more, and the content of unmodified polyolefin in the adhesive layer (B) may be, for example, 98% by mass or less. When the amount added is within such a range, the adhesive layer (B) can obtain high heat resistance and high adhesive strength at high temperatures. The total amount of the acid-modified polyolefin and the unmodified polyolefin in the adhesive layer (B) is preferably 80% by mass or more, and more preferably 90% by mass or more.

The adhesive layer (B) may further contain 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 tie layer (C) contains styrene-based elastomer, polyphenylene ether and polyolefin.

Examples of styrene-based elastomers include styrene-butadiene diblock copolymers, styrene-butadiene-styrene triblock copolymers, styrene-isoprene diblock copolymers, styrene-isoprene-styrene triblock copolymers, and hydrogenated products thereof. Among these block copolymers, styrene-ethylene-butylene block copolymers, which are hydrogenated products of styrene-butadiene block copolymers, and styrene-ethylene-propylene block copolymers, which are hydrogenated products of styrene-isoprene block copolymers, are preferably used, and styrene-ethylene-butylene-styrene triblock copolymers (hereinafter sometimes abbreviated as SEBS) and styrene-ethylene-propylene-styrene triblock copolymers (hereinafter sometimes abbreviated as SEPS) are particularly preferably used because they are readily available commercially. These block copolymers and graft copolymers may be modified with acids such as maleic anhydride, epoxy modified with an oxidizing agent, or modified with terminal amines to give functional groups such as carboxylic acid groups, carboxylic anhydride groups, epoxy groups, and amino groups. These functional groups may be effective in improving the interfacial adhesion between the substrate layer and the adhesive layer.

The polyphenylene ether may be the same as that described for the substrate layer (A). The polyphenylene ether used in the tie layer (C) may be the same as or different from the polyphenylene ether used in the substrate layer (A). The polyphenylene ether used in the tie layer (C) is preferably poly(2,6-dimethyl-1,4-phenylene) ether, as in the substrate layer (A).

Polyolefins are resins containing monomer units derived from monomers selected from the group consisting of α-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.

As a polyolefin, polypropylene is particularly preferred. Polypropylene is a polymer containing propylene units as the main component, and may be a homopolymer or copolymer, or may be an alloy or blend with other polymer components.

Specific examples of polypropylene include homopolymers such as amorphous polypropylene and crystalline polypropylene, copolymers whose main component is propylene, such as ethylene-propylene copolymers and propylene-diene monomer copolymers, halogen-modified products such as chlorinated polypropylene, and alloys or blends of polypropylene with other polymers.

Other monomer units constituting polypropylene copolymers and alloys include monomer units derived from monomers selected from the group consisting of α-olefins such as ethylene, 1-butene, 1-pentene, 1-hexene, and 4-methyl-1-pentene, diene monomers such as butadiene, isoprene, chloroprene, and diene monomers, aromatic vinyl compounds such as vinyl acetate, (meth)acrylic acid esters, and styrene, and combinations thereof. The polypropylene may be acid-modified polypropylene. Acid modification increases the affinity with the adhesive layer (B), and is expected to improve the interfacial adhesive strength.

Polyolefin can be produced by the production method described above for the adhesive layer (B), but as the polyolefin used in the tie layer (C), a polyolefin polymerized using a metallocene catalyst (hereinafter referred to as a metallocene polyolefin) is preferred, and polypropylene polymerized using a metallocene catalyst (hereinafter referred to as a metallocene polypropylene) is particularly preferred. A metallocene catalyst is a catalyst consisting of a transition metal compound of Group 4 of the periodic table containing a ligand having a cyclopentadienyl skeleton (a so-called metallocene compound), a cocatalyst that can be activated to a stable ion state by reacting with the metallocene compound, and, if necessary, an organoaluminum compound, and any known metallocene catalyst can be used. As the polymerization method, any type of method can be adopted as long as the catalyst components and each monomer are efficiently contacted. Specific polymerization methods include a slurry method in the presence of a metallocene catalyst, a gas-phase fluidized bed method, a solution method, and a high-pressure bulk polymerization method.

The mass ratio of the styrene-based elastomer to polyphenylene ether in the tie layer (C) (styrene-based elastomer/polyphenylene ether) is preferably 30/70 to 80/20, more preferably 35/65 to 70/30, and particularly preferably 40/60 to 60/40. When the mass ratio is equal to or greater than the lower limit of the above range, it is possible to increase the strength of the tie layer (C). When the mass ratio is equal to or less than the upper limit of the above range, it is possible to improve heat resistance.

The mass ratio of the total amount of the styrene-based elastomer and polyphenylene ether to the polyolefin in the tie layer (C) (total amount/polyolefin) is preferably 50/50 to 85/15, more preferably 60/40 to 80/20, and particularly preferably 70/30 to 80/20. When the mass ratio is equal to or greater than the lower limit of the above range, the adhesion to the base layer (A) can be improved. When the mass ratio is equal to or less than the upper limit of the above range, the adhesion to the adhesive layer (C) can be improved.

The total amount of the styrene-based elastomer, polyphenylene ether and polyolefin in the tie layer (C) is preferably 50% by mass or more, more preferably 70% by mass or more, and may be 100% by mass.

The melt flow rate of the tie layer (C) is preferably 0.5 g/10 min or more, more preferably 1 g/10 min or more. The melt flow rate of the tie layer (C) is preferably 50 g/10 min or less, more preferably 30 g/10 min or less. When the melt flow rate of the tie layer (C) is equal to or higher than the lower limit, the melt viscosity becomes appropriate and sheet forming becomes easy, and when it is equal to or lower than the upper limit, the melt tension becomes appropriate and sheet forming becomes easy.

Here, the melt flow rate is a value measured in accordance with JIS K7210:2014. The melt flow rate of the tie layer (C) was measured at a resin temperature of 260°C and a load of 2.16 kg.

The tie layer (C) may further comprise 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 (A) preferably has a thickness in the range of 50 to 300 μm, more preferably in the range of 70 to 250 μm, and particularly preferably in the range of 100 to 200 μm. When the thickness of the substrate layer (A) is equal to or greater than this lower limit, sufficient rigidity is obtained. When the thickness of the substrate layer (A) 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 adhesive layer (B) preferably has a thickness in the range of 10 to 100 μm, more preferably in the range of 20 to 80 μm, and particularly preferably in the range of 30 to 70 μm. When the thickness of the adhesive layer (B) is equal to or greater than this lower limit, the occurrence of poor adhesion can be suppressed. When the thickness of the adhesive layer (B) is equal to or less than this upper limit, the adhesive can be prevented from overflowing from the multilayer sheet, and defects can be prevented in articles incorporating the multilayer sheet, such as batteries.

The tie layer (C) preferably has a thickness in the range of 2 to 50 μm, more preferably in the range of 5 to 40 μm, and particularly preferably in the range of 10 to 30 μm. When the thickness of the tie layer (C) is equal to or greater than this lower limit, sufficient adhesion is obtained. When the thickness of the tie layer (C) 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.

By controlling the thickness of each layer of the multilayer sheet within this range, the multilayer sheet and the bonded body using it can exhibit excellent adhesive performance, durability, productivity, and cost-effectiveness.

The base layer (A), adhesive layer (B) and tie layer (C) can each be manufactured from a resin composition as a raw material. The resin composition as the raw material of the base layer (A), adhesive layer (B) and tie layer (C) is a composition mainly composed of resin, which is composed of the components of the base layer (A), adhesive layer (B) and tie layer (C) described above. For example, the resin composition used for each layer can be manufactured by blending and mixing the components in the above-mentioned blending ratio in any order using a super mixer, Henschel mixer, etc., and kneading and granulating using a normal kneading machine such as a single-screw extruder, twin-screw extruder, Banbury mixer, roll mixer, Brabender plastograph, co-kneader, kneader-ruder, etc. In this case, it is preferable to select a kneading and granulation method that can achieve good dispersion of each component, and kneading and granulating using a twin-screw extruder is particularly preferable from the standpoint of economy, etc.

The temperature for melt-kneading the resin composition used in the base layer (A) is preferably 150 to 320°C, more preferably 180 to 300°C, and the kneading time is usually 0.5 to 20 minutes, preferably 1 to 15 minutes.

The temperature for melt-kneading the resin composition used in the adhesive layer (B) is preferably 150 to 270°C, more preferably 170 to 250°C, and the kneading time is usually 0.5 to 20 minutes, preferably 1 to 15 minutes.

The melt-kneading temperature of the resin composition used in the tie layer (C) is preferably 150 to 320°C, more preferably 170 to 300°C, and the kneading time is usually 0.5 to 20 minutes, preferably 1 to 15 minutes.

The resin composition used in the base layer (A), the resin composition used in the adhesive layer (B), and the resin composition used in the tie layer (C) obtained in this manner can be made into multilayer sheets of various shapes according to the application by conventionally known methods such as compression molding, injection molding, extrusion molding, multilayer extrusion molding, profile extrusion molding, or blow molding.

The substrate layer (A), adhesive layer (B) and tie layer (C) may be prepared in advance as sheets and then heat-laminated to form a multilayer, or may be formed into a multilayer by simultaneously forming a sheet and forming a multilayer, as in multilayer extrusion molding. In either case, it is preferable to bring the substrate layer (A) and the tie layer (C) into contact with each other while at least one of the substrate layer (A) and the tie layer (C) is in a molten state, and bring the tie layer (C) and the adhesive layer (B) into contact with each other while at least one of the tie layer (C) and the adhesive layer (B) is in a molten state. It is more preferable to bring the substrate layer (A) and the tie layer (C) into contact with each other while both the substrate layer (A) and the tie layer (C) and the tie layer (C) and the adhesive layer (B) are in a molten state. The contact temperature is preferably 160°C or higher, more preferably 190°C or higher, and particularly preferably 220°C or higher. When the contact temperature is equal to or higher than the lower limit, fusion between the adhesive layer (B) and the tie layer (C), and between the tie layer (C) and the base layer (A) proceeds sufficiently, and the interlayer adhesive strength can be increased. The base layer (A) and the adhesive layer (B) may be contacted with the tie layer (C) simultaneously or separately.

In terms of productivity and manufacturing costs, it is preferable to form the multilayer sheet by multilayer extrusion molding. In general extrusion molding, the layered molten resin extruded from a T-die is cooled and stretched by rolls or the like to form a sheet. Multilayer molding is possible by "co-extrusion", which extrudes multiple resins simultaneously. Specific methods of co-extrusion include the "feed block method", in which the resins are joined just before the T-die, and the "multi-manifold method", in which the single layers are spread in a manifold and then joined at the lip, which is the discharge outlet of the T-die. Any of these methods or other methods may be used in the manufacture of the multilayer sheet of the present invention. The multilayer sheet extruded by multilayer extrusion molding may be subsequently heat laminated (thermocompression bonded) by a heated roll. The interlayer adhesive strength may be further improved by adding a heat lamination process. The preferable temperature conditions for the heat lamination process are as described above.

The base sheet can be manufactured by laminating the base layer (A) and the tie layer (C) in the same manner as the multilayer sheet. After the base sheet is formed, an adhesive containing an acid-modified polyolefin can be applied or laminated to provide an adhesive layer (B) on the tie layer (C) provided on the surface of the base sheet, thereby forming a multilayer sheet.

The multilayer sheet of the present invention can be bonded to an adherend formed of various materials such as metal, glass, ceramics, or plastic. This makes it possible to produce an assembly including the multilayer sheet and the adherend. For example, an assembly including the multilayer sheet can be used as a member or part of a layered battery.

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.

Various types of 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 present invention will be explained in more detail below with reference to examples. Unless otherwise specified, "parts" below means parts by mass and "%" means % by mass.

Details of the resins used in the substrate layer (A), adhesive layer (B) and tie layer (C) in Table 1 are as follows:
PPE-1: Polyphenylene ether PX100F, made by Mitsubishi Engineering Plastics, Tg = 204°C (DSC)
PPE-2: SABIC, NORYL (registered trademark) polyphenylene ether PPO630, Tg = 208 ° C. (DSC)
SEBS-1: Asahi Kasei, Tuftec (registered trademark), terminal amine-modified hydrogenated styrene-based thermoplastic elastomer (SEBS) MP10, styrene content 30%
SEBS-2: Asahi Kasei, Tuftec (registered trademark), acid-modified hydrogenated styrene-based thermoplastic elastomer (SEBS) M1913, styrene content 30%
TM55: Aronmelt (registered trademark) TM55, manufactured by Toagosei, maleic anhydride modified polyolefin, melting point 142°C, MFR 15g/10min
PP-1: Japan Polypropylene, Wintech (registered trademark) WMG03, metallocene polypropylene, melting point 142°C
PP-2: Sanallomer (registered trademark) PC630A, random polypropylene, melting point 142°C, manufactured by Sanallomer

The evaluation results shown in Table 1 were evaluated as follows:

(1) Melt Flow Rate The melt flow rate (MFR) was measured using a commercially available melt indexer (G-02 manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with JIS K7210: 2014. The measurement temperature for the base layer (A) was 300°C, the measurement temperature for the adhesive layer (B) was 230°C, and the measurement temperature for the tie layer (C) was 260°C, and all layers were measured under a load of 2.16 kg.

(2) Softening point and storage modulus The resin composition for the base layer (A) was molded into a sheet having a thickness of about 0.2 mm using a tabletop press molding machine. The resin sheet was cut into a size of 10 mm x 4.5 mm, and the viscoelastic properties were measured using a tensile viscoelasticity device (Hitachi High-Tech San-Ens Co., Ltd. DMS6100). Specifically, the temperature was raised 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 δ due to temperature were recorded. The softening point was the temperature at which the value of tan δ was the maximum value.

(3) Compression creep test The resin composition for the base layer (A) was molded into a sheet having a thickness of 1 mm using a bench press molding machine. This resin sheet was cut into a size of 10 mm x 10 mm, and five sheets were stacked to form a sample having a thickness of 5 mm. Using a heat press device (Shinto Kogyo Digital Press CYPT-50), the sample was heated at a temperature of 170 ° C. and a pressure of 6 MPa for 12 hours, and the ratio of the thickness change before and after the test to the thickness before the test was calculated as the creep rate (%).

(4) Heat shrinkage test The resin composition for the base layer (A) was molded into a sheet having a thickness of 1 mm using a tabletop press molding machine. This resin sheet was cut into a size of 10 mm x 10 mm, and five sheets were stacked to form a sample having a thickness of 5 mm. Using a heat press device (Shinto Kogyo Digital Press CYPT-50), the sample was heated at a temperature of 170 ° C. and a pressure of 6 MPa for 12 hours, and the ratio of the thickness change before and after the test to the thickness before the test was calculated as the creep rate (%). The resin composition for the base layer (A) was molded into a sheet having a thickness of about 100 μm using a tabletop press molding machine. This resin sheet was cut into a size of 200 mm x 100 mm to form a sample. The prepared sample was hung in a 180 ° C. dryer for 30 seconds, and the thermal deformation rate was calculated from the dimensional change before and after heating. The thermal deformation rate is the average of the absolute value of the change rate of the long side and the absolute value of the change rate of the short side.

(5) Hot Water Peel Test A SUS304 plate with a thickness of 0.1 mm was used as an adherend, and both sides of the multilayer sheet were sandwiched between SUS304 plates and heat-pressed (180°C, 4 seconds, 3 MPa) with a precision press to produce a bonded body. This bonded body was cut into a strip with a width of 10 mm to prepare a test piece. The bonded part of the test piece was 10 mm wide and 15 mm long. In the hot water peel test, a load cell (eDPU-50N, manufactured by Imada) was attached to a measurement stand (MX2-1000N, manufactured by Imada), a heated water bath with a hook attached to the bottom was filled with hot water at 95°C, and the test piece was immersed in the water and peeled at 30 mm/min to evaluate the peel strength (N/10 mm).

(6) Adhesion durability in water A constant load immersion test was carried out to evaluate the adhesion durability in water. The constant load immersion test is a test method in which a test piece is held in 120°C pressurized hot water under a constant peel load to evaluate the adhesion durability. The test piece is the same as that used for measuring the peel strength. One end of the handle of the test piece was connected to a fixed stand with a wire, and the other end was connected to a weight. The test piece was hung from a fixed stand installed above the water surface together with the weight in 95°C hot water, and a peel load (0.5N) was applied by the weight in the water. After 2000 hours, the test piece was taken out and the above-mentioned hot water peel test was carried out to evaluate the peel strength (N/10mm). Note that, for test pieces that peeled off and fell in less than 2000 hours, only the fall time is indicated in Table 1.

<Examples 1 to 3>
PPE-1 and SEBS-1 were mixed in the ratio shown in Table 1 and melt-kneaded at 300° C. in a twin-screw extruder (TEX25αIII, manufactured by Japan Steel Works, Ltd.) to obtain resin composition A-1 for the substrate layer (A).
PPE-2, SEBS-1, and PP-1 were mixed in the ratios shown in Table 1 and melt-kneaded at 280°C in a twin-screw extruder (TEX25αIII, manufactured by Japan Steel Works) to obtain resin compositions C-1 to C-3 for the tie layer (C), respectively.
TM55 was used as the resin composition B-1 for the adhesive layer (B).
Next, the above resin composition was molded using a T-die multilayer film molding machine (manufactured by Plastics Engineering Research Institute) so that the thickness of each layer was approximately 150 μm for the base material layer (A), approximately 50 μm for the adhesive layer (B), and approximately 25 μm for the tie layer (C), to obtain five-layer sheets of adhesive layer (B)/tie layer (C)/base material layer (A)/tie layer (C)/adhesive layer (B).

Example 4
The same resin compositions A-1 and B-1 as in Example 1 were used for the base layer (A) and adhesive layer (B).
PPE-2, SEBS-1, and PP-2 were mixed in the ratio shown in Table 1 and melt-kneaded in the same manner as in Example 1 to obtain a resin composition C-4 for the tie layer (C).
A five-layer sheet was obtained in the same manner as in Example 1.

<Examples 5 to 8>
The same resin compositions A-1 and B-1 as in Example 1 were used for the base layer (A) and adhesive layer (B).
PPE-1, SEBS-1, and PP-2 were mixed in the ratios shown in Table 1 and melt-kneaded in the same manner as in Example 1 to obtain resin compositions C-5 to C-8 for the tie layer (C), respectively.
In the same manner as in Example 1, five-layer sheets were obtained.

<Example 9>
The same resin compositions A-1 and B-1 as in Example 1 were used for the base layer (A) and adhesive layer (B).
PPE-2, SEBS-2, and PP-2 were mixed in the ratio shown in Table 1 and melt-kneaded in the same manner as in Example 1 to obtain a resin composition C-9 for the tie layer (C).
A five-layer sheet was obtained in the same manner as in Example 1.

Example 10
Resin composition A-1 for the substrate layer (A) and resin composition C-2 for the tie layer (C) used in Example 2 were molded in a T-die multilayer film molding machine (manufactured by Plastics Engineering Research Institute) to obtain a substrate sheet of tie layer (C)/substrate layer (A)/tie layer (C). Resin composition B-1 for the adhesive layer (B) was molded in a T-die monolayer film molding machine (manufactured by Technovel) to obtain a monolayer sheet of adhesive layer (B).
A single layer sheet of the adhesive layer (B) was laminated onto both sides of the three-layer sheet (190° C., 0.3 MPa, 1.8 m/min) to obtain a five-layer sheet.

<Comparative Example 1>
The same resin compositions A-1 and B-1 as in Example 1 were used for the base layer (A) and adhesive layer (B).
Without providing a tie layer (C), molding was performed using a T-die multilayer film molding machine (manufactured by Plastics Engineering Research Institute) to obtain a three-layer sheet of adhesive layer (B)/substrate layer (A)/adhesive layer (B).

<Comparative Example 2>
The same resin compositions A-1 and B-1 as in Example 1 were used for the base layer (A) and adhesive layer (B).
PPE-1 and SEBS-1 were mixed in the ratio shown in Table 1 and melt-kneaded in the same manner as in Example 1 to obtain a resin composition C-10 for the tie layer (C).
A five-layer sheet was obtained in the same manner as in Example 1.

In addition, in the test results in the table, items marked with "--" mean that they have not been evaluated.

From the results of Table 1, by using the multilayer sheet of the present invention, the adhesive strength and durability with the adherend were significantly improved. From the results of Example 1 and Comparative Example 1, it was confirmed that the base material layer (A) and the adhesive layer (B) were firmly bonded by providing the tie layer (C), and the adhesive strength with the adherend was improved. From the results of Example 5 and Example 6, it was confirmed that the adhesive strength and durability with the adherend were improved when a resin composition in which the mass ratio of the styrene-based elastomer and the polyphenylene ether is within a specific range is used as the tie layer (C). From the results of Example 6 and Example 8, it was confirmed that the adhesive strength and durability with the adherend were improved when a resin composition in which the total amount of the styrene-based elastomer and the polyphenylene ether and the mass ratio of the polyolefin are within a specific range is used as the tie layer (C). In Example 10, a base material sheet consisting of the tie layer (C) / base material layer (A) / tie layer (C) was produced, and an adhesive layer (B) was provided on both sides to produce a multilayer sheet. It was confirmed that a multilayer sheet having the same adhesive strength as Example 2 can also be produced by the manufacturing method of Example 10.
Comparing Examples 1 to 3 with Example 4, it was confirmed that the durability in water was further improved by using metallocene-based polypropylene as the polyolefin in the tie layer (C).

The multilayer sheet of the present invention 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 has a base layer (A) with excellent rigidity and heat resistance, and by adding a tie layer (C) of a specific composition to this, the interfacial strength between the base layer (A) and the adhesive layer (B) is improved, forming a strong bonded body. Therefore, the multilayer sheet of the present invention is useful as a component of a battery, and can contribute to reducing the number of battery parts and costs, and significantly improving productivity.

Other applications include, for example, electric wires and cables in which metal conductors or optical fibers are covered with resin molded products, automotive mechanism 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 sealants for various layered batteries, etc.

The disclosure of Japanese Patent Application No. 2022-203014, filed on December 20, 2022, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

A multilayer sheet comprising a substrate layer (A) containing polyphenylene ether and an adhesive layer (B) containing an acid-modified polyolefin, and further comprising a tie layer (C) between the substrate layer (A) and the adhesive layer (B) containing a styrene-based elastomer, polyphenylene ether, and a polyolefin.
The multilayer sheet according to claim 1, wherein the styrene-based elastomer is selected from the group consisting of styrene-diene block copolymers, hydrogenated styrene-diene block copolymers, modified styrene-diene block copolymers, modified hydrogenated styrene-diene block copolymers, and combinations thereof.
The multilayer sheet according to claim 1, wherein the styrene-based elastomer comprises a modified product of a hydrogenated styrene-diene block copolymer, and the modified product of the hydrogenated styrene-diene block copolymer has a functional group selected from the group consisting of a carboxylic acid group, a carboxylic anhydride group, an epoxy group, an amino group, and combinations thereof.
The multilayer sheet of claim 1, wherein the polyolefin of the tie layer (C) is polypropylene.
The multilayer sheet of claim 1, wherein the polyolefin of the tie layer (C) is a metallocene-based polypropylene.
The multilayer sheet according to claim 1, wherein the mass ratio of the styrene-based elastomer to the polyphenylene ether in the tie layer (C) is 30/70 to 80/20.
The multilayer sheet according to claim 6, wherein the mass ratio of the total amount of the styrene-based elastomer and the polyphenylene ether to the polyolefin in the tie layer (C) is 50/50 to 85/15.
The multilayer sheet according to claim 1, wherein the softening point of the substrate layer (A) is 175°C or higher.
The multilayer sheet according to claim 1, wherein the storage modulus of the base layer (A) at 160°C is 500 MPa or more.
The multilayer sheet according to claim 1, wherein the acid-modified polyolefin is a maleic anhydride-modified polyolefin.
The multilayer sheet according to claim 1, wherein the base layer (A) has a thickness of 50 to 300 μm, the adhesive layer (B) has a thickness of 10 to 100 μm, and the tie layer (C) has a thickness of 2 to 50 μm.
A substrate sheet comprising a substrate layer (A) containing polyphenylene ether and a tie layer (C) containing a styrene-based elastomer, polyphenylene ether, and a polyolefin.
The substrate sheet according to claim 12, wherein the mass ratio of the styrene-based elastomer to the polyphenylene ether in the tie layer (C) is 30/70 to 80/20.
The substrate sheet according to claim 13, wherein in the tie layer (C), the mass ratio of the total amount of the styrene-based elastomer and the polyphenylene ether to the polyolefin is 50/50 to 85/15.
A method for producing a multilayer sheet, comprising: preparing a substrate sheet including a substrate layer (A) containing polyphenylene ether and a tie layer (C) containing a styrene-based elastomer, polyphenylene ether, and a polyolefin; and laminating an adhesive layer (B) containing an acid-modified polyolefin on the tie layer (C).