Resin sheets and multilayer sheets

Abstract

To provide low-volatility resin sheets and multilayer sheets. [Solution] A resin sheet comprising polyphenylene ether and an aromatic resin containing an acid anhydride group, and its applications.

Description

Technical Field

[0001] The present disclosure relates to a resin sheet and a multilayer sheet.

Background Art

[0002] Polyphenylene ether is a thermoplastic resin excellent in mechanical strength, heat resistance, dimensional stability, etc., and is used in various applications.

[0003] For example, Patent Document 1 describes a composition containing (a) polyphenylene ether resin alone or (b) a styrene resin.

[0004] Patent Document 2 describes 100 parts by weight of a composition composed of component (a) polyphenylene ether or a polyphenylene ether containing 80% by weight or less of a styrene resin and a styrene resin, and component (b) transition alumina having a central particle size of 150 μm or less and a BET surface area of 10 m ,

[0007] , , , , , , , , , ,

[0006] , / g or more and 0.1 to 15 parts by weight of alumina.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] [[ID=…]] When polyphenylene ether is heated during processing or the like, low-molecular amine compounds (mainly dibutylamine) volatilize, causing odors, contamination, etc.

[0007] This disclosure has been made in view of these circumstances, and the problem that one embodiment of this disclosure aims to solve is to provide a low-volatility resin sheet and a multilayer sheet. [Means for solving the problem]

[0008] This disclosure includes the following aspects: <1> A resin sheet comprising polyphenylene ether and an aromatic resin containing an acid anhydride group. <2> The acid anhydride group is a carboxylic acid anhydride group. <1> The resin sheet described above. <3> Aromatic resins containing acid anhydride groups are copolymers containing structural units derived from aromatic vinyl monomers and structural units derived from unsaturated carboxylic acid anhydrides. <1> or <2> The resin sheet described above. <4> Aromatic resins containing acid anhydride groups are styrene-maleic anhydride copolymers. <1> ~ <3> A resin sheet as described in one of the following. <5> The content of constituent units derived from unsaturated carboxylic acid anhydrides is 0.2 parts by mass or more per 100 parts by mass of polyphenylene ether. <3> The resin sheet described above. <6> The amount of amine in the volatilization test at 200°C is 30 ppm by mass or less. <1> ~ <5> A resin sheet as described in one of the following. <7> <1> ~ <6> A multilayer sheet comprising a resin sheet as described above and an adhesive layer disposed on at least one of the resin sheets. <8> The adhesive layer contains an acid-modified polyolefin. <7> The multilayer sheet described above. [Effects of the Invention]

[0009] According to one embodiment of the present disclosure, a low-volatility resin sheet and a multilayer sheet are provided. [Modes for carrying out the invention]

[0010] In this specification, a numerical range indicated using "~" means a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described stepwise in this specification, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Furthermore, in the numerical ranges described in this specification, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples.

[0011] In this specification, the amount of each component in a composition means the total amount of multiple substances present in the composition, unless otherwise specified, if there are multiple substances corresponding to each component in the composition. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, provided that the intended purpose of the process is achieved.

[0012] [Resin sheet] The resin sheet of this disclosure comprises a polyphenylene ether and an aromatic resin containing an acid anhydride group.

[0013] The resin sheet of this disclosure suppresses the volatilization of volatile components (e.g., low molecular weight amine compounds) derived from polyphenylene ether compared to conventional resin sheets. Since the resin sheet of this disclosure contains an aromatic resin containing an acid anhydride group along with polyphenylene ether, it is believed that the acid anhydride group captures the amine compound, thereby suppressing the volatilization of the amine compound.

[0014] On the other hand, Patent Document 1 describes reducing volatile components derived from polyphenylene ether by adding water and degassing during kneading, but this is not easy because it requires special equipment in the extruder. In addition, Patent Document 2 reduces odor by using alumina having a specific particle size. However, since alumina is hygroscopic, moisture may vaporize and foam during film formation.

[0015] <Polyphenylene ether> The resin sheet of the present disclosure contains at least one kind of polyphenylene ether. The polyphenylene ether has a phenylene ether structure and may be either a homopolymer or a copolymer.

[0016] Regarding the linking position of phenylene in the polyphenylene ether, it may be any of o-phenylene (1,2-phenylene), m-phenylene (1,3-phenylene), and p-phenylene (1,4-phenylene), and p-phenylene (1,4-phenylene) is preferred. The linking positions of phenylene in one molecule may be the same or different from each other.

[0017] The phenylene in the polyphenylene ether may be unsubstituted or may have a substituent. Examples of the substituent include a linear or branched alkyl group having 1 to 4 carbon atoms. The substituent is preferably a methyl group or an ethyl group, and more preferably a methyl group. The substituents in one molecule may be the same or different from each other.

[0018] Examples of the polyphenylene ether include poly(2,6-dimethyl-1,4-phenylene)ether, poly(2,6-diethyl-1,4-phenylene)ether, poly(2,6-dipropyl-1,4-phenylene)ether, poly(2-methyl-6-ethyl-1,4-phenylene)ether, and poly(2-methyl-6-propyl-1,4-phenylene)ether.

[0019] The weight average molecular weight of the polyphenylene ether is preferably from 10,000 to 100,000, and more preferably from 20,000 to 50,000.

[0020] In this disclosure, the weight-average molecular weight is the molecular weight on a polystyrene basis, which can be measured by gel permeation chromatography (GPC).

[0021] The polyphenylene ether content is preferably 50% to 95% by mass, and more preferably 70% to 90% by mass, based on the total amount of the resin sheet.

[0022] In the resin sheet of this disclosure, the polyphenylene ether may be contained as a polymer alloy. Examples of polymers that can be mixed with polyphenylene ether as polymer alloys include polyamides, polypropylenes, polyphenylene sulfides, and styrene-based thermoplastic elastomers.

[0023] From the viewpoint of moldability, it is preferable that polyphenylene ether be included as a polymer alloy. The resin sheet of this disclosure preferably further comprises at least one selected from the group consisting of polyamide, polypropylene, polyphenylene sulfide, and styrene-based thermoplastic elastomer.

[0024] In particular, from the viewpoint of compatibility, the polymer mixed with polyphenylene ether is preferably a styrene-based thermoplastic elastomer.

[0025] Examples of styrene-based thermoplastic elastomers include styrene-isoprene diblock copolymer (SI), styrene-butadiene diblock copolymer (SB), styrene-isoprene-styrene triblock copolymer (SIS), styrene-butadiene / isoprene-styrene triblock copolymer (SBIS), and styrene-butadiene-styrene triblock copolymer (SBS), as well as their hydrogenated derivatives. Examples of hydrogenated derivatives include styrene-ethylene-butylene-styrene copolymer (SEBS), styrene-ethylene-propylene-styrene copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS), and styrene-butylene-butadiene-styrene copolymer (SBBS). In particular, the styrene-based thermoplastic elastomer is preferably SEBS.

[0026] If a styrene-based thermoplastic elastomer is included, the content of the styrene-based thermoplastic elastomer is preferably 5% to 50% by mass, and more preferably 10% to 30% by mass, relative to the total content of polyphenylene ether and styrene-based thermoplastic elastomer.

[0027] <Aromatic resins containing acid anhydride groups> The resin sheet of this disclosure comprises at least one aromatic resin containing an acid anhydride group.

[0028] In aromatic resins containing acid anhydride groups, the acid anhydride group is preferably a carboxylic acid anhydride group from the viewpoint of compatibility with the resin. Aromatic resins are not particularly limited as long as they contain aromatic rings. Examples of aromatic rings include aromatic hydrocarbon rings such as benzene rings, naphthalene rings, anthracene rings, and pyrene rings; and heteroaromatic rings such as pyridine rings, pyrrole rings, furan rings, thiophene rings, imidazolyl rings, and acridone rings. Among these, aromatic hydrocarbon rings are preferred.

[0029] The aromatic resin containing acid anhydride groups is preferably a copolymer containing structural units derived from aromatic vinyl monomers and structural units derived from unsaturated carboxylic acid anhydrides.

[0030] Examples of aromatic vinyl monomers include styrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, ot-butylstyrene, mt-butylstyrene, pt-butylstyrene, p-chlorostyrene, and o-chlorostyrene.

[0031] Examples of unsaturated carboxylic acid anhydrides include maleic anhydride and itaconic anhydride. In particular, from the viewpoint of having a high rate of modification or copolymerizability, the unsaturated carboxylic acid anhydride is preferably maleic anhydride.

[0032] When an aromatic resin containing an acid anhydride group is a copolymer containing structural units derived from an aromatic vinyl monomer and structural units derived from an unsaturated carboxylic acid anhydride, it is preferable that the content of structural units derived from the unsaturated carboxylic acid anhydride is 0.2 parts by mass or more per 100 parts by mass of polyphenylene ether. By having a content of 0.2 parts by mass or more of constituent units derived from unsaturated carboxylic acid anhydrides, the effect of suppressing volatile components derived from polyphenylene ether is further enhanced.

[0033] From the above viewpoint, the content of constituent units derived from unsaturated carboxylic acid anhydrides is more preferably 0.3 parts by mass or more, and even more preferably 0.6 parts by mass or more. From the viewpoint of heat resistance, it is preferable that the content of constituent units derived from unsaturated carboxylic acid anhydrides be 5 parts by mass or less.

[0034] The aromatic resin containing the acid anhydride group is preferably a styrene-maleic anhydride copolymer. In the case of a styrene-maleic anhydride copolymer, it is possible to increase the content of constituent units derived from maleic anhydride, and the effects of this disclosure can be achieved with the addition of a small amount. A styrene-maleic anhydride copolymer refers to a copolymer containing structural units derived from styrene and structural units derived from maleic anhydride.

[0035] The styrene-maleic anhydride copolymer may contain structural units other than those derived from styrene and those derived from maleic anhydride.

[0036] In a styrene-maleic anhydride copolymer, the mass ratio of the content of styrene-derived structural units to the content of maleic anhydride-derived structural units is preferably 1 to 10, and more preferably 2 to 8.

[0037] The weight-average molecular weight of the aromatic resin containing acid anhydride groups is preferably 1,000 to 100,000, and more preferably 5,000 to 30,000.

[0038] From the viewpoint of achieving both heat resistance and suppression of volatile components, the content of aromatic resin containing acid anhydride groups is preferably 0.1% to 20% by mass, and more preferably 1% to 10% by mass, based on the total amount of the resin sheet.

[0039] The resin sheet of this disclosure may contain polyphenylene ether and other components other than aromatic resins containing acid anhydride groups. Other components include additives selected from the group consisting of antioxidants, UV absorbers, fillers, reinforcing fibers, mold release agents, processing aids, flame retardants, plasticizers, nucleating agents, antistatic agents, pigments, dyes, foaming agents, and combinations thereof.

[0040] The resin sheet of this disclosure preferably has an amine content of 30 ppm by mass or less in a volatilization test at 200°C, and more preferably 10 ppm by mass or less.

[0041] The volatilization test at 200°C is performed using the following method. The resin sheet is heated from 50°C to 200°C at a rate of 10°C / min. The gaseous components that volatilize from the resin sheet are cooled and liquefied. These components are then injected into a JEOL gas chromatograph (Jms-T2000GC) and measured while the temperature is increased from 40°C to 250°C at a rate of 10°C / min. A concentration calibration curve is created by measuring several concentrations of dibutylamine as standard samples under the same conditions. By comparing the peaks of the elution times, the concentration of dibutylamine (mass ppm) in the volatile components of the resin sheet is calculated.

[0042] [Multilayer sheet] The multilayer sheet of the present disclosure includes a resin sheet of the present disclosure and an adhesive layer disposed on at least one of the resin sheets. The multilayer sheet of the present disclosure may have the resin sheet of the present disclosure as the core layer, with an adhesive layer disposed on only one side of the resin sheet, or with adhesive layers disposed on both sides of the resin sheet of the present disclosure.

[0043] The resin sheet and the adhesive layer may be in direct contact, or other layers may be placed between the resin sheet and the adhesive layer. Examples of other layers include a primer layer and a tie layer to enhance the adhesion of the adhesive layer to the resin sheet.

[0044] The thickness of the resin sheet is preferably 40 μm to 350 μm, and more preferably 60 μm to 200 μm.

[0045] In this disclosure, the thickness of each layer constituting the multilayer sheet is the arithmetic mean of the thicknesses at three locations obtained by preparing a section having a cross-section perpendicular to the main surface of the multilayer sheet and measuring it using a digital microscope VHS-8000 (manufactured by Keyence Corporation).

[0046] From the viewpoint of heat resistance and film-forming properties, the adhesive layer preferably contains an acid-modified polyolefin.

[0047] In this disclosure, acid-modified polyolefins are obtained by grafting unmodified polyolefins with acid compounds.

[0048] The unmodified polyolefin before acid modification of the acid-modified polyolefin is not particularly limited, as long as it has constituent units derived from olefins. As unmodified polyolefins, homopolymers or copolymers of olefins having 2 to 20 carbon atoms, such as ethylene, propylene, butene, pentene, hexene, heptene, octene, and 4-methyl-1-pentene, are preferred, and homopolymers or copolymers of olefins having 2 to 6 carbon atoms are more preferred.

[0049] In particular, acid-modified polyolefin is preferably acid-modified polypropylene. Acid-modified polypropylene may be a homopolymer consisting solely of structural units derived from propylene. Unmodified polypropylene may be a copolymer containing 30% by mass or less of structural units derived from monomers other than propylene.

[0050] When the unmodified polypropylene before acid modification is a copolymer, other monomers include 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; and aromatic vinyl compounds such as vinyl acetate, (meth)acrylic acid esters, and styrene.

[0051] When the unmodified polypropylene before acid modification is a copolymer, the content of constituent units derived from other monomers is preferably 50% by mass or less, and more preferably 30% by mass or less, relative to the total amount of the unmodified polypropylene.

[0052] Examples of acid compounds used to obtain acid-modified polypropylene from unmodified polypropylene include unsaturated carboxylic acids and unsaturated carboxylic acid anhydrides.

[0053] Unsaturated carboxylic acids are compounds that contain both an ethylenic double bond and a carboxyl group within the same molecule, and include unsaturated monocarboxylic acids and unsaturated dicarboxylic acids. Acid compounds may be used individually or in combination of two or more.

[0054] Examples of unsaturated monocarboxylic acids include acrylic acid, methacrylic acid, crotonic acid, and isocrotonic acid.

[0055] Examples of unsaturated dicarboxylic acids include maleic acid, fumaric acid, itaconic acid, citraconic acid, nadic acid, and endic acid.

[0056] Unsaturated carboxylic acid anhydrides are compounds that have an ethylenic double bond and a carboxylic acid anhydride group within the same molecule, and examples include the acid anhydrides of the unsaturated dicarboxylic acids mentioned above.

[0057] Examples of unsaturated dicarboxylic acid acid anhydrides include maleic anhydride, fumaric anhydride, itaconic anhydride, citraconic anhydride, nadic anhydride, and endicic anhydride.

[0058] In particular, due to its high denaturing effect, the acid compound is preferably maleic acid or maleic anhydride, and more preferably maleic anhydride. In other words, the acid-modified polypropylene is preferably maleic acid-modified polypropylene or maleic anhydride-modified polypropylene, and more preferably maleic anhydride-modified polypropylene.

[0059] Known methods can be used for graft modification. For example, one method involves grafting an acid compound with polypropylene in a molten or solution state in the presence of a radical polymerization initiator such as an organic peroxide or an aliphatic azo compound.

[0060] The preferred temperature for the graft reaction is 80°C to 160°C when the reaction is carried out in solution, and 150°C to 300°C when the reaction is carried out in molten state. In both the solution and molten states, the reaction rate is high above the lower limit of the above reaction temperature range, and the decrease in molecular weight can be suppressed below the upper limit of the above reaction temperature range, thereby maintaining the mechanical strength of the resulting acid-modified polypropylene.

[0061] The radical polymerization initiator can be appropriately selected from commercially available organic peroxides, taking into consideration the reaction temperature and other factors.

[0062] If some of the acid compounds used for graft modification remain unreacted, it is preferable to remove the unreacted acid compounds by known methods such as reduced-pressure distillation, from the viewpoint of suppressing a decrease in adhesive strength.

[0063] The weight-average molecular weight (Mw) of the acid-modified polyolefin is preferably 10,000 to 300,000, more preferably 30,000 to 250,000, and even more preferably 50,000 to 200,000.

[0064] The content of acid-modified polyolefin is preferably 0.1% by mass or more, and more preferably 1% by mass or more, relative to the total amount of the adhesive layer. If the degree of acid modification of the acid-modified polyolefin is relatively low, the content of acid-modified polyolefin may be 10% by mass or more, or even 40% by mass or more, relative to the total amount of the adhesive layer. Depending on the acid-modified polyolefin, the entire polyolefin resin may be acid-modified polyolefin.

[0065] From the viewpoint of durability due to molecular weight maintenance, the content of acid-modified polyolefin is preferably 20% by mass or less, and more preferably 10% by mass or less, relative to the total amount of the adhesive layer. If the degree of acid modification of the acid-modified polyolefin is relatively low, the content of acid-modified polyolefin may be 80% by mass or less, relative to the total amount of the adhesive layer.

[0066] The adhesive layer may contain unmodified polyolefins in addition to acid-modified polyolefins. From the viewpoint of heat resistance, the total content of polyolefin resin (including acid-modified polyolefin and unmodified polyolefin) is preferably 60% by mass or more, and more preferably 70% by mass or more, relative to the total amount of the adhesive layer. There is no particular upper limit on the polyolefin resin content, and the adhesive layer may consist solely of polyolefin resin.

[0067] The adhesive layer may contain components other than acid-modified polyolefin.

[0068] The adhesive layer may further contain additives selected from the group consisting of antioxidants, ultraviolet absorbers, fillers, reinforcing fibers, mold release agents, processing aids, flame retardants, plasticizers, nucleating agents, antistatic agents, pigments, dyes, foaming agents, and combinations thereof.

[0069] The thickness of the adhesive layer is preferably 10 μm to 100 μm, and more preferably 15 μm to 60 μm.

[0070] The multilayer sheets of this disclosure can be manufactured using known molding methods. Examples of molding methods include, but are not limited to, heat lamination, extrusion lamination, and co-extrusion.

[0071] Thermal lamination can be performed using a known laminator. There are no restrictions on the lamination conditions; general conditions can be applied. The lamination temperature is preferably 50°C to 200°C, and more preferably 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 0.01 MPa to 10 MPa, and more preferably 0.1 MPa to 5 MPa.

[0072] The multilayer sheet of this disclosure is preferably a gasket for a fuel cell.

[0073] Fuel cell gaskets can be bonded to adherends made of various materials such as metal, glass, ceramics, and plastic. This allows for the creation of a joint including the fuel cell gasket and the adherend.

[0074] The metal used as the adherend may be a commonly known metal sheet, metal plate, or metal foil, and can be iron, copper, aluminum, lead, zinc, titanium, chromium, stainless steel, etc. Among these, iron, aluminum, titanium, or stainless steel are particularly preferred.

[0075] Various thermoplastic or thermosetting resins can be used as the adherend. Composite materials may also be used, which are resins compounded with inorganic materials such as glass or ceramics, or with fillers or fibers such as metal or carbon.

[0076] The multilayer sheet of this disclosure is suitably used as a gasket placed between the electrolyte membrane and the separator of a fuel cell. For example, in the multilayer sheet of this disclosure, one adhesive layer is placed on the electrolyte membrane side, and the other adhesive layer is placed on the separator side. [Examples]

[0077] The present disclosure will be explained in more detail below with reference to examples and comparative examples, but this disclosure is not limited thereto.

[0078] [Manufacturing of resin sheets] Each component listed in Table 1 was mixed and melted in a single-layer film forming machine to produce a resin sheet with a thickness of 100 μm. Details of each component listed in Table 1 are as follows:

[0079] <Polyphenylene ether> • PPE: Product name "PX100F", manufactured by Mitsubishi Engineering Plastics Corporation, glass transition temperature: 204℃

[0080] <Aromatic resins containing acid anhydride groups> • Styrene-maleic anhydride copolymer 1 Product name: "XIRAN2000", manufactured by Polyscope Corporation. Content of styrene-derived constituent units: Content of maleic anhydride-derived constituent units = 2:1 Molecular weight: 6500 • Styrene-maleic anhydride copolymer 2 Product name: "XIRAN EF40", manufactured by Polyscope. Content of styrene-derived constituent units: Content of maleic anhydride-derived constituent units = 4:1 Molecular weight: 10000 • Styrene-maleic anhydride copolymer 3 Product name "XIRAN EF80", manufactured by Polyscope, Content of constituent units derived from styrene: Constituent units derived from maleic anhydride = 8:1 Molecular weight: 13500

[0081] <sebs> • Product name: "ToughTech (registered trademark) MP10", manufactured by Asahi Kasei Corporation, styrene ratio: 30% by mass

[0082] The resulting resin sheet was used to evaluate the suppression rate of volatile components.

[0083] A resin sheet was heated from 50°C to 200°C at a rate of 10°C / min. The gaseous components that volatilized from the resin sheet were cooled and liquefied. These components were then injected into a JEOL gas chromatograph (Jms-T2000GC) and measured while the temperature was increased from 40°C to 250°C at a rate of 10°C / min. A concentration calibration curve was created by measuring several concentrations of dibutylamine as standard samples under the same conditions. The dibutylamine (DBA) concentration in the volatile components of the resin sheet was calculated by comparing the peaks of the elution times. Furthermore, the DBA concentration of Comparative Example 1, which did not contain the styrene-maleic anhydride copolymer, was used as the baseline value, and the ratio (%) of the reduced DBA concentration to the baseline value was calculated as the suppression rate of volatile components.

[0084] [Table 1]

[0085] As shown in Table 1, it was found that volatile components derived from polyphenylene ether could be significantly suppressed in Examples 1 to 7.

[0086] [Manufacturing of multilayer sheets] -Example 8- The raw material composition for the resin sheet of Example 2 was used as the base layer composition. As the adhesive layer composition, maleic anhydride-modified polypropylene (maleic anhydride graft amount: 0.8% by mass, melt flow rate at 230°C and 2.16 MPa load: 15 g / 10 min) was used. The base layer composition and the adhesive layer composition were molded using a T-die multilayer film molding machine (manufactured by the Plastics Engineering Research Institute) so that the base layer thickness was approximately 140 μm and the adhesive layer thickness was approximately 50 μm, thereby obtaining a three-layer sheet consisting of an adhesive layer, a base layer, and another adhesive layer.

[0087] -Comparative Example 2- A three-layer sheet was obtained in the same manner as in Example 8, except that the raw material composition of the resin sheet of Comparative Example 1 was used as the base layer composition.

[0088] Using the obtained three-layer sheet, the suppression rate of volatile components was evaluated in the same manner as with the resin sheet. In Example 8, the DBA concentration of Comparative Example 2 was used as the reference value, and the ratio (%) of the reduced DBA concentration to the reference value was calculated as the suppression rate of volatile components.

[0089] As shown in Table 2, it was found that in Example 8, volatile components derived from polyphenylene ether could be significantly suppressed.

[0090] [Table 2] [Industrial applicability]

[0091] The resin sheet of this disclosure is useful as a means of suppressing volatile components of a resin sheet containing polyphenylene ether, and can contribute to cost reduction and a significant improvement in productivity.< / sebs>

Claims

1. A resin sheet comprising polyphenylene ether and an aromatic resin containing an acid anhydride group.

2. The resin sheet according to claim 1, wherein the acid anhydride group is a carboxylic acid anhydride group.

3. The resin sheet according to claim 1, wherein the aromatic resin containing the acid anhydride group is a copolymer containing structural units derived from an aromatic vinyl monomer and structural units derived from an unsaturated carboxylic acid anhydride.

4. The resin sheet according to claim 1, wherein the aromatic resin containing the acid anhydride group is a styrene-maleic anhydride copolymer.

5. The resin sheet according to claim 3, wherein the content of constituent units derived from the unsaturated carboxylic acid anhydride is 0.2 parts by mass or more per 100 parts by mass of the polyphenylene ether.

6. The resin sheet according to claim 1, wherein the amount of amine in a volatilization test at 200°C is 30 ppm by mass or less.

7. A multilayer sheet comprising a resin sheet according to any one of claims 1 to 6, and an adhesive layer disposed on at least one of the resin sheets.

8. The multilayer sheet according to claim 7, wherein the adhesive layer comprises an acid-modified polyolefin.

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