Composite sheet, method for manufacturing composite sheet, and molded body

Abstract

A composite sheet containing a thermoplastic resin composition (X) and inorganic fibers (Y), the thermoplastic resin composition (X) containing a thermoplastic resin and a thermally expandable flame retardant, and the density of the composite sheet being 1.3 g / cm3 or less. The present invention can provide a composite sheet having high flame shielding properties and light weight.

Description

Technical Field

[0001] The present invention relates to a composite sheet, a method for producing the composite sheet, and a molded body formed by molding the composite sheet. Background Art

[0002] In recent years, as part of environmental protection measures, research and development of electric vehicles and hybrid vehicles are being promoted, and high-energy-density battery development and lightweighting are being actively promoted to increase the cruising range. Such high-energy-density batteries have the potential to catch fire due to accidents. As a safety measure for passengers, the shell material needs to have high flame shielding properties. Therefore, in many cases, metal materials such as iron and refractory materials are used in combination.

[0003] However, metal materials have the disadvantage of being heavy, and when used in combination with refractory materials, processability and increased costs due to the increase in the number of parts become problems. Therefore, attempts have been made to make resins that can take into account both lightweight and flame shielding properties. Currently, in a society oriented towards sustainable development, the suppression of carbon dioxide and recyclability are gradually gaining attention. Thermosetting materials often have high flame retardancy and are very common as composite materials, but from the perspective of recyclability, thermoplastic resin raw materials are advantageous.

[0004] In addition, China has issued safety standards such as GB 38031-2020 "Safety Requirements for Power Batteries for Electric Vehicles", which stipulates that a warning must be issued 5 minutes before the battery's thermal runaway. It can be assumed that this can also be achieved through the shell material that shields the flame for more than 5 minutes after the battery catches fire.

[0005] To address these problems, for example, Patent Document 1 proposes a material in which a bromine-based flame retardant or an antimony oxide compound is added to a carbon fiber-reinforced polypropylene resin. However, the additives used here have a problem in terms of biopersistence.

[0006] In contrast, Patent Document 2 proposes a flame-retardant polyolefin composition containing a (poly)phosphate compound in a polyolefin resin as a technique for flame-retarding a polypropylene resin in consideration of biopersistence.

[0007] In addition, Patent Document 3 proposes a flame-retardant resin composition comprising long glass fibers and a phosphate compound contained in a polypropylene resin.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2014-62189

[0011] Patent Document 2: Japanese Patent Application Publication No. 2013-119575

[0012] Patent Document 3: Japanese Patent Application Publication No. 2011-88970 Summary of the invention

[0013] Problems to be solved by the invention

[0014] There are many deficiencies in the existing fiber-reinforced composite material technology that can achieve both lightweight and flame-barrier properties for high-energy-density batteries. Specifically, fiber-reinforced composite materials are required to have high flame-barrier properties and further improvements in lightweight properties.

[0015] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a molded product having high flame shielding properties and light weight, and a composite sheet for obtaining the molded product.

[0016] Solutions to the problem

[0017] The present inventors have conducted intensive studies to solve the above-mentioned problems and have found that a composite sheet of a thermoplastic resin and inorganic fibers containing a heat-expandable flame retardant in a thermoplastic resin, and a molded body formed by molding the composite sheet can solve the above-mentioned problems, and have completed the present invention based on these findings.

[0018] That is, the present invention provides the following [1] to

[15] .

[0019] [1] A composite sheet comprising a thermoplastic resin composition (X) and inorganic fibers (Y),

[0020] The thermoplastic resin composition (X) comprises a thermoplastic resin and a heat-expandable flame retardant,

[0021] The density of the composite sheet is 1.3 g / cm 3 the following.

[0022] [2] The composite sheet according to [1] above, wherein

[0023] When observing the cut surface of the composite sheet, there are multiple cross-sectional areas of 0.01mm 2 The pores above have a cross-sectional area of ​​0.01 mm 2 The average cross-sectional area of ​​the above pores is 0.03 mm 2 Above and 0.8mm 2 the following.

[0024] [3] The composite sheet according to [1] or [2] above, wherein the thickness ratio before and after heating at 1200° C. for 15 minutes (thickness after high temperature test / thickness before high temperature test) is 5 times or less.

[0025] [4] The composite sheet according to any one of [1] to [3] above, comprising a top sheet comprising a nonwoven fabric formed of resin fibers.

[0026] [5] The composite sheet according to any one of [1] to [4] above, wherein

[0027] The thermally expandable flame retardant includes a phosphorus-based flame retardant.

[0028] [6] The composite sheet according to any one of [1] to [5] above, wherein

[0029] The thermoplastic resin constituting the thermoplastic resin composition (X) includes a polyolefin resin.

[0030] [7] The composite sheet according to any one of [1] to [6] above, wherein

[0031] The above-mentioned thermoplastic resin composition (X) further contains a dispersant.

[0032] [8] The composite sheet according to [7] above, wherein

[0033] The above dispersant includes a copolymer of an α-olefin and an unsaturated carboxylic acid.

[0034] [9] The composite sheet according to [7] or [8] above, wherein

[0035] The content of the dispersant is more than 0 and 25 parts by mass or less based on 100 parts by mass of the heat-expandable flame retardant.

[0036]

[10] The composite sheet according to any one of [1] to [9] above, wherein

[0037] The inorganic fibers (Y) include at least one selected from the group consisting of glass fibers, ceramic fibers, metal fibers, and metal oxide fibers.

[0038]

[11] The composite sheet according to any one of [1] to

[10] above, wherein a mat composed of inorganic fibers (Y) is impregnated with the thermoplastic resin composition (X).

[0039]

[12] The method for producing a composite sheet according to any one of [1] to

[11] above, comprising:

[0040] A sheet composed of the thermoplastic resin composition (X) is stacked on a mat composed of the inorganic fibers (Y), and the mixture is heated and melted to impregnate the mat with the thermoplastic resin composition (X).

[0041]

[13] The method for producing a composite sheet according to

[12] above, wherein:

[0042] The mat composed of the inorganic fibers (Y) is laminated so as to be located between two sheets composed of the thermoplastic resin composition (X).

[0043]

[14] A molded body obtained by molding the composite sheet according to any one of [1] to

[11] above.

[0044]

[15] The molded article according to

[14] above, which is used for a battery case.

[0045] Effects of the Invention

[0046] According to the present invention, a molded product having high flame shielding properties and light weight, and a composite sheet for obtaining the molded product can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram showing the production process of the composite sheet of the present invention.

[0048] Figure 2 This is a schematic diagram showing the composite sheet of Example 1.

[0049] Explanation of symbols

[0050] 10-layer stack

[0051] 11 Fiberglass Mat

[0052] 12 Surface Sheets

[0053] 13 Thermoplastic resin sheet

[0054] 20 resin impregnated sheet

[0055] 30 composite tablets

[0056] 31PP sheet

[0057] 32 Fiberglass Mat

[0058] 33PP sheet

[0059] 34PET non-woven fabric DETAILED DESCRIPTION

[0060] Hereinafter, an embodiment of the present invention will be described in detail. However, the following description is an example of the embodiment of the present invention, and the present invention is not limited to these contents at all.

[0061] [Compound sheet]

[0062] The composite sheet of the present invention is characterized in that it comprises a thermoplastic resin composition (X) and an inorganic fiber (Y), wherein the thermoplastic resin composition (X) comprises a thermoplastic resin and a heat-expandable flame retardant, and the density of the composite sheet is 1.3 g / cm 3 the following.

[0063] The density of the composite sheet is 1.3g / cm 3 From the above viewpoints, the density of the composite sheet can be 1.2 g / cm 3 Below, or 1.0g / cm 3 Below, or 0.7g / cm 3 On the other hand, from the viewpoint of flame shielding property and strength of the composite sheet, the density of the composite sheet is preferably 0.1 g / cm 3 From this point of view, the density of the composite sheet can be 0.2 g / cm 3 Above, or 0.3g / cm 3 above.

[0064] Generally speaking, it is expected that the flame shielding property of the composite sheet will decrease as the density of the composite sheet decreases. However, the inventors unexpectedly found that the composite sheet of the present invention can ensure flame shielding property at a relatively low density. The reason is not clear, but it can be considered as follows: the density of the composite sheet is 1.3 g / cm 3 When the volume of the interstitial space in the composite sheet increases, the heat-expandable flame retardant contained in the composite sheet of the present invention expands in the interstitial space to form a dense char.

[0065] In order to make the density of the composite sheet 1.3g / cm 3 The following method is as follows: the resin impregnated sheet described later is heated to expand, and then the space in the mold is adjusted, thereby pressurizing and compressing the resin impregnated sheet arranged in the mold until the resin impregnated sheet reaches a given density. The heating temperature is preferably in the range of 180 to 250°C, more preferably in the range of 200 to 240°C, and further preferably in the range of 210 to 230°C. By setting the heating temperature to these ranges, moderate expansion can be caused to obtain a density of 1.3 g / cm 3 The composite sheet with suppressed strength reduction is described below. It should be noted that the method for producing the composite sheet will be described in detail below.

[0066] [Method for producing composite sheet]

[0067] The method for producing the composite sheet of the present invention will be described in detail later. Here, for the case where a glass fiber mat, a surface sheet, and a thermoplastic resin sheet are used, the following method is used. Figure 1Each step will be described. In the following, the case where glass fibers are used as the inorganic fibers (Y) will be described as an example.

[0068] Step (a): Overlaying the surface sheet 12 on both sides of the glass fiber mat 11, and overlaying the thermoplastic resin sheet 13 on the outside. That is, the glass fiber mat 11 becomes a layer structure sandwiched by the surface sheet 12, and the surface sheet 12 becomes a layer structure sandwiched by the glass fiber mat 11 and the thermoplastic resin sheet 13 ( Figure 1 (a)).

[0069] Step (b): Then, the laminate 10 having the above-mentioned layer structure is heated and pressurized. By heating and pressurizing, the thermoplastic resin sheet 13 is melted and impregnated into the voids in the glass fiber mat 11 and the voids in the surface sheet 12, thereby obtaining a resin-impregnated sheet 20 ( Figure 1 (b)).

[0070] Step (c): The resin-impregnated sheet 20 is cooled and pressurized, and the thermoplastic resin solidifies in the gaps in the glass fiber mat 11 and the gaps in the surface sheet 12, respectively, to form a layer structure in which the surface sheet 12 is bonded to both sides of the glass fiber mat 11.

[0071] Step (d): The resin-impregnated sheet 20 obtained in step (c) is subjected to a heat treatment, whereby the thermoplastic resin solidified in the voids in the glass fiber mat 11 and the voids in the surface sheet 12 is melted, and the glass fiber mat 11 expands due to the rebound of the fibers. Due to this rebound, the void ratio in the surface sheet 12 becomes smaller than the void ratio in the glass fiber mat 11. Then, the thermoplastic resin solidifies in the voids in the glass fiber mat 11 and the voids in the surface sheet 12 by natural cooling, and becomes a composite sheet having a greater thickness than that after step (c), for example, a thickness of more than twice.

[0072] As the surface sheet 12 used in the above process, nonwoven fabric is preferred. Figure 1 As shown in (b), the composite sheet of the present invention preferably has a top sheet 12 made of a nonwoven fabric formed of resin fibers.

[0073] The fiber used here is preferably formed of a fiber of a resin selected from polypropylene, polyester, polyethylene, nylon, vinylon, rayon, acrylic acid, aramid, polylactic acid, etc. By using a non-woven fabric, it is easy to pass through the gaps in the surface sheet 12 and impregnate the gaps in the glass fiber mat 11 when the thermoplastic resin sheet 13 is melted.

[0074] In addition, since the softening temperature of the resin fiber constituting the surface sheet 12 is higher than the softening temperature of the thermoplastic resin sheet 13, the shape of the surface sheet 12 can be maintained even when the thermoplastic resin sheet 13 is melted and the thermoplastic resin is impregnated into the gaps in the glass fiber mat 11 and the gaps in the surface sheet 12 respectively.

[0075] Furthermore, when the surface sheet 12 is impregnated with a thermoplastic resin, the bonding strength of the surface sheet 12 to the glass fiber mat 11 can be increased, and the non-peeling property of the surface sheet 12 can be improved.

[0076] Here, the thermoplastic resin sheet 13 is preferably formed of, for example, one resin selected from polypropylene, polyethylene, polyamide, polyester, and the like.

[0077] In addition, in the composite sheet of the present invention, it is preferred that when observing the cut surface of the composite sheet, there are a plurality of 2 The pores above have a cross-sectional area of ​​0.01 mm 2 The average cross-sectional area of ​​the above pores is 0.03 mm 2 Above and 0.8mm 2 When the average cross-sectional area of ​​the pores in the composite sheet is within the above range, flame shielding properties and light weight can be achieved at a high level. 2 The average cross-sectional area of ​​the above pores can be 0.05 mm 2 Above, or 0.1mm 2 Above, or 0.15mm 2 Above, or 0.2mm 2 On the other hand, it can be 0.7mm 2 Below, or 0.6mm 2 Below, or 0.5mm 2 As a method for observing the pores and measuring the cross-sectional area, the composite sheet can be cut using a cutter or the like, and the cut surface can be observed using an optical microscope or the like. The cross-sectional area of ​​the pores can be measured using general image analysis software.

[0078] In addition, the thickness ratio of the composite sheet of the present invention before and after heating at 1200°C for 15 minutes (thickness after high temperature test / thickness before high temperature test) is preferably 5 times or less. When it is 5 times or less, the density reduction caused by expansion can be suppressed, and the strength reduction caused by the density reduction can be suppressed. From the above viewpoints, the thickness ratio before and after heating is more preferably 4 times or less, and further preferably 3.5 times or less. On the other hand, when the thickness ratio before and after heating is 1.2 times or more, a thermal expansion layer can be formed by expansion to obtain excellent flame shielding properties. From the above viewpoints, the thickness ratio before and after heating is more preferably 1.5 times or more.

[0079] Hereinafter, each component used in the present invention and the obtained composite sheet will be described in detail.

[0080] <Thermoplastic resin composition (X)>

[0081] The thermoplastic resin composition (X) used for the composite sheet of the present invention is characterized by comprising (a) a thermoplastic resin and (b) a heat-expandable flame retardant.

[0082] (a) Thermoplastic resin

[0083] The thermoplastic resin contained in the thermoplastic resin composition (X) of the present invention is not particularly limited, and examples thereof include polyolefin resins, polycarbonate resins, polyester resins, acrylonitrile styrene resins, ABS resins, polyamide resins, and modified polyphenylene ethers. Among them, in the present invention, polyolefin resins are preferred. It should be noted that one or more of them may be used. For example, the thermoplastic resin (a) may be a composite resin of two or more of the above thermoplastic resins.

[0084] The polyolefin resin is not particularly limited, and the resins described below can be cited. The polyester resin is not particularly limited, and an example thereof is polybutylene terephthalate. The polyamide resin is not particularly limited, and an example thereof is nylon 66 and nylon 6.

[0085] The present invention is particularly useful when at least a polyolefin resin is included as (a) a thermoplastic resin. It should be noted that in the present invention, "polyolefin resin" refers to a resin in which the proportion of olefin units or cycloolefin units is 90 mol% or more relative to 100 mol% of all constituent units constituting the resin.

[0086] The proportion of the olefin unit or the cycloolefin unit relative to 100 mol % of all the structural units constituting the polyolefin resin is preferably 95 mol % or more, particularly preferably 98 mol % or more.

[0087] Examples of polyolefin resins include polyethylene, polypropylene, polybutene, poly(3-methyl-1-butene), poly(3-methyl-1-pentene), poly(4-methyl-1-pentene) and other α-olefin polymers; ethylene-propylene block or random copolymers, α-olefin-propylene block or random copolymers having 4 or more carbon atoms, ethylene-methyl methacrylate copolymers, ethylene-vinyl acetate copolymers and other α-olefin copolymers; polycyclohexene, polycyclopentene and other cycloolefin polymers. Examples of polyethylene include low-density polyethylene, linear low-density polyethylene, and high-density polyethylene. Examples of polypropylene include isotactic polypropylene, syndiotactic polypropylene, hemiisotactic polypropylene, and stereoblock polypropylene. Examples of α-olefins having 4 or more carbon atoms in α-olefin-propylene block or random copolymers include butene, 3-methyl-1-butene, 3-methyl-1-pentene, and 4-methyl-1-pentene. These polyolefin resins may be used alone or in combination of two or more.

[0088] Among the above-mentioned olefin resins, polypropylene resin (hereinafter sometimes referred to as “PP resin”) is particularly preferred.

[0089] (Melt Flow Rate (MFR))

[0090] The melt flow rate (hereinafter sometimes referred to as MFR) (230°C, 2.16 kg load) of the (a) thermoplastic resin used in the present invention is preferably 40 to 500 g / 10 minutes. When the MFR is 40 g / 10 minutes or more, for example, when a molded body is obtained by stamping, no defects will occur, and the processability will not be reduced. In addition, when it is 500 g / 10 minutes or less, burrs will not be generated in the manufacture of the composite sheet. From the above viewpoints, the MFR is preferably 50 to 400 g / 10 minutes, more preferably 60 to 400 g / 10 minutes, and more preferably 70 to 300 g / 10 minutes.

[0091] The MFR of the (a) thermoplastic resin can be adjusted by, for example, controlling the hydrogen concentration during polymerization.

[0092] In addition, MFR is a value measured according to JIS K7210.

[0093] ((a) Content of thermoplastic resin)

[0094] The content of the (a) thermoplastic resin in the composite sheet of the present invention is not particularly limited, and is preferably 15 to 80% by mass in the thermoplastic resin composition (X). When the content of the (a) thermoplastic resin is 15% by mass or more, the molding processability becomes particularly good, and the molding of the composite sheet becomes easy. On the other hand, when it is 80% by mass or less, a flame retardant, a dispersant and an inorganic fiber can be contained in sufficient amounts to obtain good flame shielding properties. From the above viewpoints, the content of the (a) thermoplastic resin in the thermoplastic resin composition (X) is preferably 35 to 70% by mass, more preferably 40 to 60% by mass.

[0095] <(a-1) Polypropylene resin>

[0096] The (a) thermoplastic resin used in the composite sheet of the present invention preferably includes a polypropylene resin. Examples of the polypropylene resin include propylene homopolymers and propylene-α-olefin copolymers. The propylene-α-olefin copolymer may be any of a random copolymer and a block copolymer.

[0097] (α-Olefins)

[0098] As the α-olefin constituting the above-mentioned copolymer, for example, ethylene, 1-butene, 2-methyl-1-propylene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 1-heptene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1-pentene, trimethyl-1-butene, 1-octene, etc. These can be copolymerized with propylene using one kind, and in addition, two or more kinds can be copolymerized with propylene. Among them, from the viewpoint of improving the impact resistance of the composite sheet, ethylene or 1-butene having a large effect is preferred, and ethylene is most preferred.

[0099] (Propylene-ethylene random copolymer)

[0100] In the case of a random copolymer of propylene and ethylene, it is preferably 90 to 99.5% by mass, more preferably 92 to 99% by mass of propylene units, and it is preferably 0.5 to 10% by mass, more preferably 1 to 8% by mass of ethylene units. When the ethylene units are above the lower limit, sufficient impact strength of the composite sheet can be obtained, and when it is below the upper limit, sufficient rigidity can be maintained.

[0101] The contents of propylene units and ethylene units in the random copolymer of propylene and ethylene can be adjusted by controlling the composition ratio of propylene to ethylene during the polymerization of the random copolymer of propylene and ethylene.

[0102] The propylene content of the random copolymer of propylene and ethylene is a value measured using a cross-classifier, FT-IR or the like, and the measurement conditions and the like may be determined by the method described in, for example, JP-A-2008-189893.

[0103] (Melt Flow Rate (MFR))

[0104] The MFR (230°C, 2.16 kg load) of the (a-1) polypropylene resin used in the present invention is preferably 40 to 500 g / 10 minutes. When the MFR is 40 g / 10 minutes or more, no defects will occur when a molded body is obtained by stamping, etc., and the processability will not be reduced. In addition, when it is 500 g / 10 minutes or less, burrs will not be generated in the manufacture of the composite sheet. From the above viewpoints, the MFR is preferably 50 to 400 g / 10 minutes, more preferably 60 to 400 g / 10 minutes, and further preferably 70 to 300 g / 10 minutes.

[0105] The MFR of the (a-1) polypropylene-based resin (propylene homopolymer) can be adjusted by controlling the hydrogen concentration during polymerization.

[0106] In addition, MFR is a value measured according to JIS K7210.

[0107] ((a-1) Content of polypropylene resin)

[0108] The content of (a-1) polypropylene resin in the composite sheet of the present invention is not particularly limited, and is preferably 15 to 80% by mass. When the content of polypropylene resin is 15% by mass or more, the molding processability becomes sufficient, and the molding of the composite sheet becomes easy. On the other hand, when it is 80% by mass or less, the content of flame retardant, dispersant and inorganic fiber becomes sufficient, and sufficient flame shielding can be obtained. From the above viewpoints, the content of polypropylene resin in the composite sheet is more preferably 35 to 70% by mass, and further more preferably 40 to 60% by mass.

[0109] <Modified polyolefin resin>

[0110] The composite sheet of the present invention may contain a modified polyolefin resin in addition to the above-mentioned polypropylene resin. Specific examples of the modified polyolefin resin include acid-modified polyolefin resins and hydroxy-modified polyolefin resins, which may be used alone or in combination.

[0111] It should be noted that the types of the acid-modified polyolefin-based resin and the hydroxy-modified polyolefin-based resin used as the modified polyolefin-based resin are not particularly limited, and any conventionally known modified polyolefin-based resin may be used.

[0112] (Acid-modified polyolefin resin)

[0113] Examples of acid-modified polyolefin resins include resins obtained by graft copolymerizing and chemically modifying polyolefins such as polyethylene, polypropylene, ethylene-α-olefin copolymers, ethylene-α-olefin-non-conjugated diene compound copolymers (EPDM, etc.), and ethylene-aromatic monovinyl compound-conjugated diene compound copolymer elastomers using unsaturated carboxylic acids such as maleic acid or maleic anhydride.

[0114] The graft copolymerization can be carried out by reacting the polyolefin with an unsaturated carboxylic acid in a suitable solvent using a free radical generator such as benzoyl peroxide. In addition, the unsaturated carboxylic acid or its derivative component can also be introduced into the polymer chain by random or block copolymerization with a polyolefin monomer.

[0115] Examples of the unsaturated carboxylic acid used for modification include compounds having a polymerizable double bond into which a carboxyl group and, if necessary, a hydroxyl group, an amino group or the like are introduced, such as maleic acid, fumaric acid, itaconic acid, acrylic acid, and methacrylic acid.

[0116] Derivatives of unsaturated carboxylic acids include anhydrides, esters, amides, imides, metal salts, etc., and specific examples thereof include maleic anhydride, itaconic anhydride, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, etc. Among them, maleic anhydride is preferred.

[0117] Preferred acid-modified polyolefin resins include resins modified by grafting maleic anhydride with an olefin polymer having ethylene and / or propylene as main polymer constituent units, resins modified by copolymerizing an olefin having ethylene and / or propylene as main components with maleic anhydride, etc. Specifically, combinations of polyethylene / maleic anhydride grafted ethylene-butene-1 copolymers, or combinations of polypropylene / maleic anhydride grafted polypropylene, etc. may be mentioned.

[0118] (Hydroxy-modified polyolefin resin)

[0119] The hydroxy-modified polyolefin resin is a modified polyolefin resin containing a hydroxy group. The hydroxy-modified polyolefin resin may have a hydroxy group at an appropriate position, for example, at the terminal of the main chain or at a side chain.

[0120] Examples of the olefin resin constituting the hydroxy-modified polyolefin resin include single products or copolymers of α-olefins such as ethylene, propylene, butene, 4-methylpentene-1, hexene, octene, nonene, decene, and dodecene, and copolymers of the above α-olefins and copolymerizable monomers.

[0121] Preferred hydroxy-modified polyolefin resins include, for example, low-density, medium-density or high-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, ethylene-(methyl)acrylate copolymers, ethylene-vinyl acetate copolymers and other hydroxy-modified polyethylene resins, polypropylene homopolymers such as isotactic polypropylene, random copolymers of propylene and α-olefins (such as ethylene, butene, hexane, etc.), propylene-α-olefin block copolymers, and hydroxy-modified polypropylene resins such as hydroxy-modified poly(4-methylpentene-1).

[0122] <(b) Thermally expandable flame retardant>

[0123] The thermoplastic resin composition (X) forming the composite sheet of the present invention contains (b) a heat-expandable flame retardant. (b) The heat-expandable flame retardant refers to a flame retardant that inhibits the combustion of the material by forming a surface expansion layer (intumescent) that prevents the diffusion of radiant heat from the combustion source, combustion gas and smoke from the combustion product to the outside.

[0124] Among the heat-expandable flame retardants, phosphorus-based flame retardants are preferred, and examples thereof include salts of (poly)phosphoric acid and nitrogen compounds (hereinafter also referred to as "compound (b1)"). Specifically, examples thereof include ammonium salts and amine salts of (poly)phosphoric acid such as ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, ammonium pyrophosphate, melamine pyrophosphate, and piperazine pyrophosphate.

[0125] In addition, examples of nitrogen compounds include ammonia, melamine, piperazine, and other nitrogen compounds. Examples of other nitrogen compounds include N,N,N',N'-tetramethyldiaminomethane, ethylenediamine, N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-diethylethylenediamine, 1,2-propanediol, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-diethylethylenediamine, 1,2-propanediol, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-diethylethylenediamine, 1,2-propanediol, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-diethylethylenediamine, 1,2-propanediol, N,N'-dimethylethylenediamine, N ... diamine, 1,3-propylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, trans-2,5-dimethylpiperazine, 1,4-bis(2-aminoethyl)piperazine, 1,4-bis(3-aminopropyl)piperazine, acetoguanamine, benzoguanamine, acrylic guanamine, 2,4-diamino-6-nonyl-1,3,5-triazine , 2,4-diamino-6-hydroxy-1,3,5-triazine, 2-amino-4,6-dihydroxy-1,3,5-triazine, 2,4-diamino-6-methoxy-1,3,5-triazine, 2,4-diamino-6-ethoxy-1,3,5-triazine, 2,4-diamino-6-propoxy-1,3,5-triazine, 2,4-diamino-6-isopropoxy-1,3,5-triazine, 2,4-diamino-6-mercapto-1,3 ,5-triazine, 2-amino-4,6-dimercapto-1,3,5-triazine, cyanuric acid diamide, benzoguanamine, acetoguanamine, o-phthaloguanamine, melamine isocyanurate, butylene diguanamine, norbornene diguanamine, methylene diguanamine, ethylene dimelamine, trimethylene dimelamine, tetramethylene dimelamine, hexamethylene dimelamine, 1,3-hexamethylene dimelamine, etc.

[0126] <Other flame retardants>

[0127] As described above, the composite sheet of the present invention is characterized by containing a heat-expandable flame retardant, but other flame retardants may be used in combination with the heat-expandable flame retardant. The other flame retardant is not particularly limited, and conventionally used flame retardants may be used.

[0128] Specifically, examples thereof include phosphorus-based flame retardants other than the above-mentioned heat-expandable flame retardants, bromine-based flame retardants, antimony-based flame retardants, etc. Among them, phosphorus-based flame retardants are preferred from the viewpoint of improving flame barrier properties.

[0129] (Phosphorus flame retardant)

[0130] The phosphorus-based flame retardant is a phosphorus compound, that is, a compound containing a phosphorus atom in a molecule. The phosphorus-based flame retardant forms a char when the composite sheet is burned, thereby exhibiting a flame retardant effect.

[0131] The phosphorus flame retardant may be a known phosphorus flame retardant, for example, (poly)phosphate, (poly)phosphate ester, etc. Here, "(poly)phosphate" means a phosphate or a polyphosphate, and "(poly)phosphate ester" means a phosphate ester or a polyphosphate ester.

[0132] It should be noted that the phosphorus-based flame retardant is preferably solid at 80°C.

[0133] As the phosphorus-based flame retardant, (poly)phosphate is preferred from the viewpoint of flame retardancy.

[0134] Examples of the (poly)phosphate include ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, piperazine orthophosphate, melamine pyrophosphate, piperazine pyrophosphate, melamine polyphosphate, and melamine orthophosphate. Examples of other phosphorus flame retardants include calcium phosphate and magnesium phosphate.

[0135] In the above examples, compounds obtained by replacing melamine or piperazine with other nitrogen compounds can also be used in the same manner. These (poly)phosphates may be used alone or in combination of two or more.

[0136] Examples of commercially available phosphorus flame retardants include ADK STAB FP-2100J, FP-2200, and FP-2500S (manufactured by ADEKA Corporation).

[0137] (Brominated flame retardants)

[0138] Examples of the bromine-based flame retardant include decabromodiphenyl ether, tetrabromobisphenol A, tetrabromobisphenol S, 1,2-bis(2',3',4',5',6'-pentabromophenyl)ethane, 1,2-bis(2,4,6-tribromophenoxy)ethane, 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine, 2,6-dibromophenol, 2,4-dibromophenol, brominated polystyrene, ethylenebistetrabromophthalimide, hexabromocyclododecane, hexabromobenzene, pentabromobenzyl acrylate, 2,2-bis[4'(2'',3''-dibromopropoxy)-3',5'-dibromophenyl]-propane, bis[3,5-dibromo-4-(2,3-dibromopropoxy)phenyl]sulfone, and tris(2,3-dibromopropyl)isocyanurate.

[0139] (Antimony flame retardant)

[0140] Examples of the antimony flame retardant include antimony trioxide, antimony tetroxide, antimony pentoxide, sodium pyroantimonate, antimony trichloride, antimony trisulfide, antimony oxychloride, antimony dichloride perchloropentane, and potassium antimonate. Antimony trioxide and antimony pentoxide are particularly preferred.

[0141] Among the flame retardants mentioned above, phosphorus-based flame retardants are preferred from the viewpoint of having no bioresidue and excellent flame retardancy, and halogen-free flame retardants are preferred from the viewpoint of environmental friendliness.

[0142] In addition, the above flame retardants may be used alone or in combination of two or more.

[0143] ((b) Content of thermal expansion flame retardant)

[0144] The content of the heat-expandable flame retardant in the composite sheet of the present invention is not particularly limited, and is preferably in the range of 1 to 30% by mass. When it is 1% by mass or more, it is possible to impart good flame retardancy to the composite sheet, and good flame shielding properties can be obtained. On the other hand, when the flame retardant is 30% by mass or less, it is possible to contain a thermoplastic resin with a sufficient content ratio, and therefore, molding processability becomes better. From the above viewpoints, the content of the heat-expandable flame retardant in the composite sheet is more preferably in the range of 1 to 25% by mass, and further preferably in the range of 3 to 20% by mass.

[0145] <(c) Dispersant>

[0146] It is preferred that the thermoplastic resin composition (X) of the present invention further contains a dispersant.

[0147] As (c) dispersant, as long as (b) heat-expandable flame retardant can be dispersed in (a) thermoplastic resin, there is no particular limitation, and from the aspect of compatibility with (a) thermoplastic resin, polymer dispersant can be suitably used. Preferably, a dispersant that can disperse (b) heat-expandable flame retardant in (a-1) polypropylene resin is used. As polymer dispersant, a polymer dispersant with functional groups is preferably used, and from the aspect of dispersion stability, a polymer dispersant with functional groups such as carboxyl, phosphoric acid, sulfonic acid, primary, secondary or tertiary amino, quaternary ammonium salt, and groups from nitrogen-containing heterocyclics such as pyridine, pyrimidine, and pyrazine is preferably used.

[0148] In the present invention, preferably, a polymer dispersant having a carboxyl group is used, and particularly, when a suitable phosphorus-based flame retardant is used as the flame retardant, preferably, a copolymer of an alpha-olefin and an unsaturated carboxylic acid is used. By using the dispersant, the dispersibility of the phosphorus-based heat-expandable flame retardant can be improved, and the content of the heat-expandable flame retardant can be reduced.

[0149] (Copolymer of α-olefin and unsaturated carboxylic acid)

[0150] The ratio of the α-olefin unit in the total of 100 mol % of the α-olefin unit and the unsaturated carboxylic acid unit in the "copolymer of α-olefin and unsaturated carboxylic acid" (hereinafter referred to as "copolymer (c1)") of the present invention is preferably 20 mol % to 80 mol %.

[0151] In the copolymer (c1), the ratio of the α-olefin unit to the total amount of the α-olefin unit and the unsaturated carboxylic acid unit is more preferably 30 mol% or more, and on the other hand, it is more preferably 70 mol% or less. When the ratio of the α-olefin is above the above lower limit, the compatibility with the polyolefin resin becomes better, and when it is below the above upper limit, the compatibility with the (b) thermal expansion flame retardant becomes better.

[0152] In the copolymer (c1), the α-olefin is preferably an α-olefin having 5 or more carbon atoms, and more preferably an α-olefin having 10 or more and 80 or less carbon atoms. When the carbon number of the α-olefin is 5 or more, there is a tendency for the compatibility with the thermoplastic resin (a) to become better, and when it is 80 or less, it is advantageous from the perspective of raw material cost. From the above viewpoints, the carbon number of the α-olefin is more preferably 12 or more and 70 or less, and particularly preferably 18 or more and 60 or less.

[0153] In the copolymer (c1), unsaturated carboxylic acids include, for example, (meth)acrylic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, tetrahydrophthalic acid, itaconic acid, crotonic acid, isocrotonic acid, glutaconic acid, norbornyl-5-ene-2,3-dicarboxylic acid, and esters, anhydrides, and imides of these unsaturated carboxylic acids. It should be noted that "(meth)acrylic acid" means acrylic acid or methacrylic acid.

[0154] Specific examples of esters, anhydrides or imides of unsaturated carboxylic acids include (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and glycidyl (meth)acrylate; dicarboxylic anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride; maleimide compounds such as maleimide, N-ethylmaleimide, and N-phenylmaleimide, etc. These may be used alone or in combination of two or more.

[0155] Among the above, esters and dicarboxylic anhydrides are preferred from the viewpoint of copolymerization reactivity. Among them, dicarboxylic anhydrides are preferred from the viewpoint of compatibility with a suitable thermally expandable phosphorus-based flame retardant as a flame retardant, and maleic anhydride is particularly preferred.

[0156] The weight average molecular weight of the copolymer (c1) is preferably 2000 or more, more preferably 3000 or more, and is preferably 50000 or less, more preferably 30000 or less. When the weight average molecular weight of the copolymer (c1) is within the above range, the dispersibility of the flame retardant (b) becomes more excellent.

[0157] The weight average molecular weight of the copolymer (c1) is a value calculated in terms of standard polystyrene obtained by dissolving the copolymer (c1) in tetrahydrofuran (THF) and measuring the result by gel permeation chromatography.

[0158] Examples of commercially available products of the copolymer (c1) include Licolub CE2 (manufactured by CLARIANT JAPAN) and DIACARNA 30M (manufactured by Mitsubishi Chemical Corporation).

[0159] The content of the (c) dispersant in the composite sheet of the present invention is more than 0 and 25 parts by mass or less, preferably 0.01 to 10 parts by mass, based on 100 parts by mass of the (b) heat-expandable flame retardant.

[0160] According to the research of the present inventors, by using thermoplastic resin as matrix resin and making heat-expandable flame retardant uniformly dispersed and present in inorganic fibers constituting composite sheets, the flame shielding property of composite sheets can be significantly improved. The detailed mechanism is not clear, but the present inventors speculate as follows. That is, in the case where heat-expandable flame retardant is uniformly dispersed in the resin between inorganic fibers, the coke formed by heat-expandable flame retardant contacting the flame is fixed to the gap between inorganic fibers. Further, the size of the coke formed by expansion when contacting the flame is limited by the gap between inorganic fibers, and thus, the size of the coke formed becomes uniform. It can be considered that by combining the fixing effect of the coke based on inorganic fibers with the homogenization of the size of the coke, a dense coke can be formed, which significantly improves the flame shielding property of composite sheets. Based on these insights, the present inventors found that by setting the ratio of the content of the dispersant to the heat-expandable flame retardant to a specific range, it is possible to control so that the heat-expandable flame retardant is uniformly present in the resin between inorganic fibers, which can significantly improve the flame shielding property of composite sheets.

[0161] Based on the above reasons, when the content of (c) dispersant is greater than 0, the dispersibility of (b) flame retardant becomes sufficient, and sufficient flame shielding can be given to the composite sheet. On the other hand, when it is less than 25 parts by mass, the physical properties of the composite sheet become sufficient. From the same point of view, the content of (c) dispersant is preferably more than 0.01 parts by mass, more preferably more than 0.1 parts by mass, further preferably more than 1 part by mass, and particularly preferably more than 2 parts by mass. On the other hand, with respect to the upper limit value, it is more preferably less than 20 parts by mass, more preferably less than 15 parts by mass, further more preferably less than 10 parts by mass, further more preferably less than 5 parts by mass, and particularly preferably less than 3 parts by mass.

[0162] In addition, the ratio of (c) dispersant to a total of 100 parts by mass of (a) thermoplastic resin and (b) heat-expandable flame retardant is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and further preferably 0.1 parts by mass or more. On the other hand, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, more preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less, and further preferably 1.0 parts by mass or less. When the ratio of (c) dispersant is above the lower limit, (b) heat-expandable flame retardant is more well dispersed, and the flame shielding, physical properties, and appearance of the obtained composite sheet become better. When the ratio of (c) dispersant is below the upper limit, the influence of (c) dispersant on the flame shielding of the composite sheet can be further suppressed. In particular, the ratio of (c) dispersant to a total of 100 parts by mass of polyolefin resin and (b) heat-expandable flame retardant is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and further preferably 0.1 parts by mass or more. On the other hand, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, further preferably 2.0 parts by mass or less, further preferably 1.5 parts by mass or less, further preferably 1.0 parts by mass or less.

[0163] In addition, for the (Y) inorganic fiber described in detail below, the ratio of the (c) dispersant to 100 parts by mass of the (Y) inorganic fiber is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and further preferably 0.1 parts by mass or more. On the other hand, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, and further preferably 2.0 parts by mass or less. When the ratio of the (c) dispersant is above the above lower limit, the flame shielding properties, physical properties and appearance of the obtained composite sheet become better. When the ratio of the (c) dispersant is below the above upper limit, the influence of the (c) dispersant on the flame shielding properties of the composite sheet can be further suppressed.

[0164] <(Y) Inorganic fiber>

[0165] The composite sheet of the present invention contains (Y) inorganic fibers. As (Y) inorganic fibers, various fibers can be used, for example: glass fibers, rock wool, alumina fibers, metal oxide fibers such as silica alumina fibers, potassium titanate fibers, calcium silicate (wollastonite) fibers, ceramic fibers such as ceramic fibers, carbon fibers, metal fibers, etc. These inorganic fibers can be used alone or in combination of two or more.

[0166] Among the above-mentioned inorganic fibers, at least one selected from glass fibers and alumina fibers is preferred from the viewpoint of flame shielding properties and processability.

[0167] As (Y) inorganic fiber, two or more inorganic fibers having different melting temperatures may be included. As a combination of two or more inorganic fibers having different melting temperatures, it is preferred that at least one of the inorganic fibers is glass fiber and the other one or more inorganic fibers are selected from alumina fiber, silica fiber, alkaline earth silicate fiber (biosoluble) and carbon fiber. By including two or more inorganic fibers having different melting temperatures, it is possible to effectively prevent the flame shielding function from being reduced.

[0168] In addition, the inorganic fibers used in the present invention may be used in combination with a sizing agent or a surface treatment agent. Examples of such sizing agents or surface treatment agents include compounds having functional groups such as epoxy compounds, silane compounds, and titanate compounds.

[0169] The average fiber diameter of the inorganic fibers is preferably 3 to 25 μm, and the average fiber length is preferably 0.1 mm or more, more preferably 1 mm or more, and even more preferably 5 mm or more.

[0170] It should be noted that the suitable ranges of the average fiber diameter and the average fiber length vary depending on the type of inorganic material constituting the inorganic fibers, and the specific suitable ranges will be described later.

[0171] In addition, the fiber diameter can be measured using a scanning electron microscope, etc., and the average fiber diameter can be obtained by, for example, randomly measuring the fiber diameters of 10 fibers and calculating the average value. In addition, the fiber length can be measured using a ruler, a vernier caliper, etc. from an image magnified by a microscope as needed, and the average fiber length can be obtained by, for example, randomly measuring the fiber lengths of 10 fibers and calculating the average value.

[0172] The content of inorganic fibers in the composite sheet of the present invention is preferably 1 to 80% by mass. When the content of inorganic fibers is 1% by mass or more, the strength, rigidity and impact resistance of the composite sheet become good. In addition, when it is 80% by mass or less, the manufacture and processing of the composite sheet become easy. In addition, when the content of inorganic fibers is 80% by mass or less, the specific gravity of the composite sheet becomes lighter, and the lightweight effect as a metal substitute is obvious.

[0173] From the above viewpoints, the content of the (Y) inorganic fibers in the composite sheet is more preferably 3 to 60% by mass, further preferably 10 to 50% by mass, and particularly preferably 30 to 45% by mass.

[0174] (Fiberglass)

[0175] As one of the (Y) inorganic fibers suitable for the composite sheet of the present invention, glass fibers can be cited. As glass fibers, for example, long fibers with an average fiber length of 30 mm or more can be fibers with a short average fiber length (chopped strands). From the viewpoints of flame shielding, rigidity, impact resistance, etc., glass fibers with a long average fiber length are preferably used.

[0176] More specifically, the average fiber length is preferably 5 mm or more. When the average fiber length is 5 mm or more, the strength and impact resistance of the composite sheet become good. From the above viewpoints, the average fiber length of the glass fiber is preferably 5 mm or more, and more preferably 30 mm or more.

[0177] It should be noted that there is no particular upper limit on the average fiber length of the glass fiber. For example, in the case of particles produced by using glass fibers through pultrusion, the length of the particles becomes the fiber length of the glass fibers, so the maximum is about 20 mm. In addition, in swirl mats using long glass fibers, the length of the glass fibers in the roving used for production becomes the maximum fiber length, so it will reach about 17000 m (17 km), but when cut according to the size of the composite sheet, the length after cutting becomes the maximum fiber length.

[0178] In addition, the average fiber diameter of the glass fiber is preferably in the range of 9 to 25 μm. When the average fiber diameter is 9 μm or more, the rigidity and impact resistance of the composite sheet become sufficient, while when the average fiber diameter is 25 μm or less, the strength of the composite sheet becomes good. From the above viewpoints, the average fiber diameter of the glass fiber is more preferably in the range of 10 to 15 μm.

[0179] In addition, the average fiber diameter and the average fiber length of the glass fiber can be measured by the above-mentioned method.

[0180] The material of the glass fiber used in the present invention is not particularly limited, and may be any of alkali-free glass, low-alkali glass, and alkali-containing glass, and materials of various compositions conventionally used as glass fibers may be used.

[0181] (Alumina Fiber)

[0182] As one of the (Y) inorganic fibers suitable for the composite sheet of the present invention, alumina fibers can be cited. Alumina fibers are generally fibers formed of alumina and silica, and in the composite sheet of the present invention, the composition ratio (mass ratio) of alumina / silica of the alumina fibers is preferably in the range of 65 / 35 to 98 / 2, which is called a mullite composition or a high alumina composition, more preferably in the range of 70 / 30 to 95 / 5, and particularly preferably in the range of 70 / 30 to 74 / 26.

[0183] The average fiber diameter of the alumina fibers is preferably in the range of 3 to 25 μm, and preferably substantially no fibers with a fiber diameter of 3 μm or less are included. Here, substantially no fibers with a fiber diameter of 3 μm or less means that fibers with a fiber diameter of 3 μm or less account for less than 0.1% by mass of the total inorganic fiber mass.

[0184] In addition, the average fiber diameter of the alumina fiber is more preferably 5 to 8 μm. If the average fiber diameter of the inorganic fiber is too thick, the resilience and toughness of the mat-shaped inorganic fiber assembly layer will decrease. On the contrary, if it is too thin, the amount of dust floating in the air will increase, and the probability of containing inorganic fibers with a fiber diameter of 3 μm or less will increase.

[0185] The alumina fibers preferably have an average fiber length of 5 mm or more, more preferably 30 mm or more, and even more preferably 50 mm or more. 3 mm or less, more preferably 1.0×10 3 When the average fiber length and average fiber diameter of the alumina fibers are within this range, the strength and impact resistance of the composite sheet become good.

[0186] (Carbon Fiber)

[0187] The suitable range of carbon fiber is also the same as that of glass fiber.

[0188] <Optional Additives>

[0189] In addition to the above-mentioned components, the composite sheet of the present invention may further contain any additional components for the purpose of further improving the effects of the present invention or imparting other effects, within a range that does not significantly impair the effects of the present invention.

[0190] Specifically, the colorants include pigments, light stabilizers such as hindered amines, ultraviolet absorbers such as benzotriazoles, nucleating agents such as sorbitols, antioxidants such as phenols and phosphorus, antistatic agents such as nonionic surfactants, neutralizing agents such as inorganic compounds, antibacterial / antifungal agents such as thiazoles, halogen compounds, flame retardants / flame retardant aids such as lignophenol, plasticizers, dispersants such as organic metal salts, lubricants such as fatty acid amides, metal deactivators such as nitrogen compounds, thermoplastic resins such as polyolefin resins other than the above-mentioned polypropylene resins, polyamide resins, and polyester resins, and elastomers (rubber components) such as olefin elastomers and styrene elastomers.

[0191] These optional additional components may be used in combination of two or more.

[0192] Colorants such as inorganic and organic pigments are effective for imparting or improving the colored appearance, aesthetics, feel, commercial value, weather resistance, durability, etc. of the composite sheet of the present invention.

[0193] As specific examples, inorganic pigments include carbon black such as furnace carbon and ketjen carbon; titanium oxide; iron oxide (red iron, etc.); chromic acid (chrome yellow, etc.); molybdic acid; selenium sulfide; ferrocyanide, etc., and organic pigments include azo pigments such as poorly soluble azo lakes, soluble azo lakes, insoluble azo chelates; condensed azo chelates; other azo chelates; phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; threne pigments such as anthraquinone, perinone, perylene, and thioindigo; dye lakes; quinacridones; diazine; Oxazine; isoindolinone, etc. In addition, in order to make a metallic style or a pearl style, aluminum flakes and pearl pigments may be contained. In addition, dyes may also be contained.

[0194] Light stabilizers and ultraviolet absorbers such as hindered amine compounds, benzotriazoles, benzophenones, salicylates, etc. are effective in imparting and improving the weather resistance and durability of the composite sheet of the present invention, and are effective in further improving the weather resistance and discoloration.

[0195] As specific examples, hindered amine compounds include condensates of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine; poly[[6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino]]; 1,2,3,4-butanetetracarboxylic acid tetra(2,2,6,6-tetramethyl-4-piperidyl) ester; 1,2,3,4-butanetetracarboxylic acid tetra(1,2,2,6,6-pentamethyl-4-piperidyl) ester; decanetetracarboxylic acid tetra(1,2,2,6,6-pentamethyl-4-piperidyl) ester; Examples of the benzotriazoles include 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole and 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole. Examples of the benzophenones include 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-octyloxybenzophenone. Examples of the salicylic acid esters include 4-tert-butylphenyl salicylate and 2,4-di-tert-butylphenyl 3',5'-di-tert-butyl-4'-hydroxybenzoate.

[0196] Here, a method of using the above-mentioned light stabilizer and ultraviolet absorber in combination is preferred because it has a significant effect of improving weather resistance, durability, weather resistance and discoloration.

[0197] As the antioxidant, for example, phenolic, phosphorus, sulfur-based antioxidants and the like are effective for imparting or improving the heat resistance stability, processing stability, heat aging resistance and the like of the composite sheet of the present invention.

[0198] In addition, as the antistatic agent, for example, nonionic, cationic or other antistatic agents are effective in imparting or improving the antistatic property of the composite sheet of the present invention.

[0199] As olefin elastomers, for example, there can be mentioned: ethylene / α-olefin copolymer elastomers such as ethylene / propylene copolymer elastomer (EPR), ethylene-butene copolymer elastomer (EBR), ethylene / hexene copolymer elastomer (EHR), ethylene / octene copolymer elastomer (EOR); ethylene / α-olefin / diene terpolymer elastomers such as ethylene / propylene / ethylidene norbornene copolymer, ethylene / propylene / butadiene copolymer, ethylene / propylene / isoprene copolymer; styrene / butadiene / styrene triblock copolymer elastomer (SBS), etc.

[0200] In addition, examples of styrene-based elastomers include styrene / isoprene / styrene triblock copolymer elastomers (SIS), styrene-ethylene / butylene copolymer elastomers (SEB), styrene-ethylene / propylene copolymer elastomers (SEP), styrene-ethylene / butylene-styrene copolymer elastomers (SEBS), styrene-ethylene / butylene-ethylene copolymer elastomers (SEBC), hydrogenated styrene / butadiene elastomers (HSBR), styrene-ethylene / propylene-styrene copolymer elastomers (SEPS), styrene-ethylene / ethylene / propylene-styrene copolymer elastomers (SEEPS), styrene-butadiene / butylene-styrene copolymer elastomers (SBBS), partially hydrogenated styrene-isoprene-styrene copolymer elastomers, partially hydrogenated styrene-isoprene / butadiene-styrene copolymer elastomers and the like, and hydrogenated polymer-based elastomers such as ethylene-ethylene / butylene-ethylene copolymer elastomers (CEBC) and the like.

[0201] Among them, when ethylene-octene copolymer elastomer (EOR) and / or ethylene-butene copolymer elastomer (EBR) are used, it is preferred for the polypropylene resin composition and composite sheet of the present invention because they can easily impart appropriate flexibility and tend to have excellent impact resistance.

[0202] <Method for producing thermoplastic resin composition (X)>

[0203] As described above, the thermoplastic resin composition (X) of the present invention contains (a) a thermoplastic resin, a modified polyolefin resin added as needed, (b) a heat-expandable flame retardant, and (c) a dispersant. In addition, any additional components may be further formulated. In the above-mentioned thermoplastic resin composition (X), when (a) the thermoplastic resin is (a-1) a polypropylene resin, it is sometimes specifically referred to as a polypropylene resin composition (hereinafter sometimes described as a "PP composition").

[0204] As a method for producing the thermoplastic resin composition (X) or the PP composition, a conventionally known method can be utilized, and the composition can be produced by blending the above-mentioned components, mixing, and melt-kneading.

[0205] Mixing can be performed using a mixer such as a tumbler, a V mixer, or a ribbon mixer, and melt kneading can be performed using a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll mixer, a Brabender mixer, a kneader, or the like to perform melt kneading and granulation.

[0206] <Method for producing composite sheet>

[0207] The composite sheet of the present invention is not particularly limited in its production method, but is preferably produced by impregnating the thermoplastic resin composition (X) or the PP composition into a mat composed of (Y) inorganic fibers (hereinafter sometimes referred to as "inorganic fiber mat"). That is, as one embodiment of the composite sheet, the thermoplastic resin composition (X) is impregnated into a mat composed of inorganic fibers (Y).

[0208] As the impregnation method, there are the following methods: a method of applying a thermoplastic composition (X) or a PP composition to an inorganic fiber mat (Y); a method of pre-preparing a sheet of a thermoplastic resin composition (X) or a PP composition (hereinafter sometimes referred to as a "thermoplastic resin sheet" or a "PP sheet"), laminating the thermoplastic resin sheet or the PP sheet on the inorganic fiber mat (Y), heating it, melting it, and impregnating it, etc.

[0209] In the present invention, from the viewpoint of impregnation of the resin in the composite sheet into the fiber, a method of laminating a thermoplastic resin sheet or a PP sheet on an inorganic fiber mat (Y), heating and melting the sheet is preferred. In particular, the inorganic fiber mat can be laminated so that the inorganic fiber mat is located between two thermoplastic resin sheets or PP sheets, and then the laminate is heated and pressurized, followed by cooling and solidification.

[0210] Here, the thickness of the thermoplastic resin sheet or the PP sheet is not particularly limited as long as it is within a range that allows the fiber mat to be impregnated satisfactorily.

[0211] It should be noted that, as described above, it is important for the composite sheet of the present invention to have a density of 1.3 g / cm 3 Next, the resin-impregnated sheet is expanded by heating or the like to reduce the density and obtain a composite sheet.

[0212] (Inorganic fiber mat)

[0213] The form of the inorganic fibers used in the method for producing the composite sheet is not particularly limited, and various forms of inorganic fibers can be used. However, inorganic fibers in a mat or sheet form are preferred.

[0214] More specifically, a mat formed of glass fibers (hereinafter referred to as “glass fiber mat”) or a mat formed of metal oxide fibers represented by alumina fibers (hereinafter referred to as “metal oxide mat”) is preferred.

[0215] The weight per unit area (average mass per unit area) of the inorganic fiber mat is not particularly limited and can be appropriately determined according to the intended use, but is preferably 300 g / m 2 More than 800 g / m 2 , more preferably greater than 1500g / m 2In addition, the weight per unit area of ​​the inorganic fiber mat is not particularly limited, but is preferably 5000 g / m 2 Below, more preferably 4500g / m 2 Below, more preferably 4000g / m 2 Below, particularly preferably 3500g / m 2 the following.

[0216] The thickness of the inorganic fiber mat of the present invention is not particularly limited, but is preferably 4 mm or more, more preferably 5 mm or more, and further preferably 6 mm or more. In addition, the thickness of the fiber mat is preferably 40 mm or less, further preferably 35 mm or less, and particularly preferably 30 mm or less.

[0217] By adjusting the average fiber amount per unit area when stacking the inorganic fiber aggregates constituting the inorganic fiber mat using a folding device, the average unit area weight per unit area of ​​the inorganic fiber mat (weight per unit area) can be set to the above range. In addition, the inorganic fiber mat of the present invention can be a structure formed by bonding multiple inorganic fiber mats or a single structure. From the perspective of handleability and peel strength at the bonding interface, a single structure is preferred.

[0218] (Fiberglass Mat)

[0219] As the form of the glass fiber mat used in the present invention, there can be mentioned felts and blankets obtained by processing short fiber glass wool, chopped strand mats obtained by processing continuous glass fibers, eddy current (swirl) mats of continuous glass fibers, unidirectionally drawn mats, etc. Among them, it is particularly preferred to use a glass fiber mat obtained by needle-punching a eddy current (swirl) mat of continuous glass fibers because the composite sheet has excellent strength and impact resistance.

[0220] (Metal Oxide Fiber Mat)

[0221] The metal oxide fiber mat of the present invention is a mat composed of metal oxide fibers such as alumina fibers and subjected to a needle punching treatment.

[0222] In the method of laminating a thermoplastic resin sheet or a PP sheet on an inorganic fiber mat, heating, and melting it, the heating temperature is preferably 170 to 300° C. When the heating temperature is 170° C. or higher, the fluidity of the polypropylene resin is sufficient, and the PP composition can be fully impregnated into the inorganic fiber mat, and a suitable resin-impregnated sheet can be obtained. On the other hand, when the heating temperature is 300° C. or lower, the thermoplastic resin composition or the PP composition does not deteriorate.

[0223] In addition, the pressurization pressure is preferably 0.1 to 1 MPa. When the pressurization pressure is 0.1 MPa or more, the thermoplastic resin composition or PP composition can be fully impregnated into the inorganic fiber mat, and a suitable resin-impregnated sheet can be obtained. On the other hand, by setting it to 1 MPa or less, the thermoplastic resin composition or PP composition flows and burrs are not generated.

[0224] The cooling temperature is not particularly limited as long as it is below the solidification point of the thermoplastic resin in the thermoplastic resin composition (X) or the PP composition. When the cooling temperature is 80° C. or below, the obtained resin-impregnated sheet will not be deformed when taken out. From the above viewpoints, the cooling temperature is preferably room temperature to 80° C.

[0225] As a method for obtaining a composite sheet by heating, pressurizing, and cooling the resin-impregnated sheet, the composite sheet can be produced by a method of performing compression molding in a mold with a heating device, or a lamination process in which the composite sheet is passed between two pairs of rollers with a heating device to perform heating and pressurization, etc. Lamination is particularly preferred because it allows continuous production and has good productivity.

[0226] <Thickness of composite sheet>

[0227] The thickness of the composite sheet of the present invention is usually 1 to 10 mm, preferably 2 to 5 mm. When the thickness of the composite sheet is 1 mm or more, the composite sheet can be easily manufactured. On the other hand, when the thickness of the composite sheet is 10 mm or less, when the composite sheet is processed by stamping, long-term preheating is not required, and good molding processability can be obtained.

[0228] <Molding body>

[0229] The molded article of the present invention is obtained by molding the composite sheet described above. The molding method is not particularly limited, and the composite sheet can be obtained in a desired shape by press molding the composite sheet described above according to a conventional method.

[0230] (use)

[0231] The molded article of the present invention can be used in various industrial fields such as automobile parts and electrical and electronic equipment parts. In particular, since the molded article has excellent strength, rigidity and conductivity, it can be suitably used in applications that require these properties to be more highly balanced, such as various housings and frames such as battery cases.

[0232] [Structure]

[0233] The structure formed using the molded article of the present invention is not particularly limited, and there is a form including a battery case and a battery cell, for example.

[0234] The structure formed by using the molded body of the present invention is preferably a battery, and the battery is not particularly limited. For example, secondary batteries such as lithium-ion batteries, nickel / hydrogen batteries, lithium / sulfur batteries, nickel / cadmium batteries, nickel / iron batteries, nickel / zinc batteries, sodium / sulfur batteries, lead storage batteries, and air batteries can be cited. Among them, lithium-ion batteries are preferred, and in particular, the battery casing of the present invention can be suitably used to suppress thermal runaway of lithium-ion batteries.

[0235] [Electric vehicles]

[0236] A structure formed using the molded article of the present invention is also useful for electric vehicles.

[0237] Here, the electric vehicle refers to transportation equipment such as vehicles, ships, and airplanes that run on electricity as an energy source. It should be noted that the vehicle includes hybrid vehicles in addition to electric vehicles (EVs).

[0238] A structure such as a battery having a battery case and a battery cell using the molded article of the present invention has high safety and is very useful for electric vehicles using a battery module with an increased energy density in order to extend the driving distance.

[0239] Example

[0240] Hereinafter, the present invention will be described in detail using Examples, but the present invention is not limited to these Examples.

[0241] (Evaluation method)

[0242] 1. Evaluation of flame shielding properties

[0243] For the composite sheets prepared in each embodiment and comparative example, one surface was exposed to the flame of a burner at 1300°C, and the flame was evaluated according to whether it penetrated after 15 minutes. The distance from the burner nozzle to the sample was set to 160 mm. The flame surface was set to reach 1200°C. The flame surface temperature was confirmed by a thermocouple thermometer.

[0244] 2. Evaluation of thermal insulation

[0245] In the flame shielding evaluation described in 1. above, the temperature of the surface (back side) of the test piece opposite to the surface in contact with the flame of the burner was measured by a non-contact radiation thermometer ("FT-H50K" manufactured by Keyence). The measurement area is φ35mm. The center of the measurement area was set by visual observation in a manner near the position directly above the burner flame. Table 1 shows the highest temperature (°C) reached on the back side until 600 seconds have passed, and the time (seconds) when the back side temperature first reaches 500°C.

[0246] 3. Evaluation of flame retardancy

[0247] The composite sheets prepared in each example and comparative example were evaluated for flame retardancy based on the UL94 50W (20 mm) vertical burning test. The evaluation was based on whether V-1 was achieved.

[0248] 4. Expansion rate

[0249] The thickness of the composite sheet prepared in each example was measured before and after the heating test, and the expansion rate was evaluated from the ratio of the thickness of the test piece after heating to the thickness of the test piece before the heating test.

[0250] (Heating test conditions)

[0251] The test piece was subjected to a heat treatment at 1200° C. for 15 minutes in the atmosphere.

[0252] 5. Determination of pore cross-sectional area

[0253] The composite sheets prepared in each example were cut by a cutter manufactured by DAHLE, and the cross-sections were observed at 30 times using a digital microscope "VHX-6000" manufactured by Keyence to obtain cross-sectional images. The cross-sectional area of ​​the voids (pores) was measured using the automatic area measurement tool of VHX-6000. The cross-sectional area was calculated to be 0.01 mm 2 The average cross-sectional area of ​​the pores above.

[0254] 6. Determination of flexural strength after firing

[0255] The composite sheets prepared in each example were heat treated at 700°C for 20 minutes in a nitrogen atmosphere (under oxygen-free conditions). A 100 mm × 50 mm test piece was cut from the heat-treated sheet, and the bending strength of the test piece was measured using AUTOGRAPH "AG-10TA" (manufactured by Shimadzu Corporation) at a test speed of 20 mm / min and a span of 100 mm.

[0256] 7. Determination of thermal conductivity after sintering

[0257] The composite sheets prepared in each example were heated at 700°C for 20 minutes in a nitrogen atmosphere (under oxygen-free conditions). A 150 mm × 100 mm test piece was cut from the heat-treated sheet. The thermal conductivity of the sample was calculated by comparing the temperature difference between the heating surface and the heat dissipation surface when the test sample was heated on one side with the temperature difference of the sheet sample with known thermal conductivity.

[0258] (Materials used)

[0259] 1. Polypropylene resin (component a)

[0260] “NOVATEC PP SA06GA” (melt flow rate: 60 g / 10 minutes) manufactured by Japan Polypropylene Co., Ltd. was used.

[0261] 2. Thermal expansion flame retardant (component b)

[0262] The phosphorus-based flame retardant composition (ADK STAB FP-2500S manufactured by ADEKA Corporation, containing 50-60% by mass of piperazine pyrophosphate, 35-45% by mass of melamine pyrophosphate, and 3-6% by mass of zinc oxide) is used.

[0263] 3. Dispersant (component C)

[0264] α-Olein / maleic anhydride copolymer (manufactured by Mitsubishi Chemical Corporation, DIACANNA 30M, weight average molecular weight 7800).

[0265] 4. Glass fiber mat (Y component)

[0266] A vortex mat (weight per unit area 880 g / m2) made of continuous roving glass fiber (fiber diameter 23 μm) was used. 2 ) is a glass fiber mat obtained by needle punching.

[0267] 5. PET non-woven fabric

[0268] PET nonwoven fabric ("VOLANS (registered trademark) 3401ND", manufactured by Toyobo Co., Ltd., weight per unit area 40 g / m 2 )

[0269] Preparation Example 1 (Preparation of PP composition)

[0270] The above-mentioned component a, component b and component c were mixed in proportions of 68 mass %, 30 mass % and 2 mass %, respectively, and melt-kneaded (230° C.) to prepare pellets of a polypropylene resin composition (PP composition).

[0271] Comparative Preparation Example 1

[0272] In Preparation Example 1, pellets of a polypropylene-based resin composition (PP composition) were prepared in the same manner as in Preparation Example 1, except that the component b and the component c were not used.

[0273] Example 1

[0274] Below, using Figure 2The method for manufacturing the composite sheet 30 of the present invention is described. It should be noted that: Figure 2 The layer structure before the glass fiber mat is impregnated with the thermoplastic resin composition is shown.

[0275] The pellets of the PP composition granulated in Preparation Example 1 are added to an extruder, and after melting, they are extruded into a sheet shape, and the glass fiber mat 32 is sandwiched from both sides of the extruded sheet PP sheet 31 and laminated. Further, PET non-woven fabric 34 is laminated on both sides, and PP sheet 33 is laminated on both sides in a manner that forms the outermost layer. Then, while applying a pressure of 0.3 MPa using a laminator, it is heated and pressurized at 230°C for 1 minute and 30 seconds, and then cooled and solidified to obtain a resin-impregnated sheet (thickness; 2.5 mm). The PP sheet is impregnated with the glass fiber mat to obtain an integrated resin-impregnated sheet. The mass ratio of the resin-impregnated sheet is PP sheet: PET non-woven fabric: glass fiber mat = 25:1:16. The resin-impregnated sheet is expanded by heating it at 220°C for 2 minutes, and is compressed in a mold adjusted to a given thickness to obtain a sheet with a density of 0.67 g / cm 3 The results of the evaluation by the above method are shown in Table 1. It should be noted that the thickness of the composite sheet before heating by the flame shield test was 5.4 mm, and the thickness after heating was 10.1 mm. The expansion ratio before and after the heating test was 1.9 times. In addition, the cross-section of the composite sheet was observed, and multiple pores with a cross-sectional area of ​​0.01 mm or more were observed. The average cross-sectional area of ​​pores with a cross-sectional area of ​​0.01 mm or more is 0.21 mm 2 .

[0276] Example 2

[0277] In Example 1, except that the mold was adjusted so as to have a predetermined thickness, a density of 0.84 g / cm was obtained in the same manner as in Example 1. 3 The results obtained by evaluating in the same manner as in Example 1 are shown in Table 1. It should be noted that the thickness of the composite sheet before heating by the flame shield test was 4.3 mm, and the thickness after heating was 8.3 mm. The expansion ratio before and after the heating test was 1.9 times. In addition, the average cross-sectional area of ​​pores with a cross-sectional area of ​​0.01 mm or more obtained by observing the cross section of the composite sheet was 0.15 mm 2 .

[0278] Example 3

[0279] In Example 1, except that the mold was adjusted so as to have a predetermined thickness, a density of 1.12 g / cm was obtained in the same manner as in Example 1. 3The results obtained by evaluating in the same manner as in Example 1 are shown in Table 1. It should be noted that the thickness of the composite sheet before heating by the flame shield test was 3.3 mm, and the thickness after heating was 10.1 mm. The expansion ratio before and after the heating test was 3.1 times. In addition, the average cross-sectional area of ​​pores with a cross-sectional area of ​​0.01 mm or more obtained by observing the cross section of the composite sheet was 0.06 mm. 2 .

[0280] Comparative Example 1

[0281] In Example 1, a composite sheet was obtained in the same manner as in Example 1 except that the pellets of the PP composition granulated in Comparative Preparation Example 1 were used instead of the pellets of the PP composition granulated in Preparation Example 1. The density of the composite sheet was 0.61 g / cm 3 The evaluation results are shown in Table 1. The thickness of the composite sheet before heating by the flame shielding test was 5.3 mm. In the flame shielding test, the flame penetrated the back surface to form holes, so the thickness after heating could not be measured.

[0282] Comparative Example 2

[0283] In Comparative Example 1, except that the mold was adjusted so as to have a predetermined thickness, a density of 0.76 g / cm was obtained in the same manner as in Comparative Example 1. 3 The results of the evaluation performed in the same manner as in Example 1 are shown in Table 1. It should be noted that the thickness of the composite sheet before heating by the flame shielding test was 4.3 mm. In the flame shielding test, the flame penetrated the back surface and formed a hole, so the thickness after heating could not be measured.

[0284] Comparative Example 3

[0285] In Comparative Example 1, except that the mold was adjusted so as to have a predetermined thickness, a density of 1.02 g / cm was obtained in the same manner as in Comparative Example 1. 3 The results of the evaluation performed in the same manner as in Example 1 are shown in Table 1. It should be noted that the thickness of the composite sheet before heating by the flame shielding test was 3.3 mm. In the flame shielding test, the flame penetrated the back surface and formed a hole, so the thickness after heating could not be measured.

[0286]

[0287] As shown in Examples 1 to 3, the composite sheet of the present invention has excellent flame shielding properties, and the flame was shielded even after 15 minutes had passed. In addition, the result was equivalent to V-1 in the UL94 test.

[0288] In contrast, the flame penetrated to the back surface in 87 seconds in Comparative Example 1, 94 seconds in Comparative Example 2, and about 95 seconds in Comparative Example 3. In addition, Comparative Examples 1 and 3 did not satisfy the V-1 standard.

[0289] Furthermore, as shown in Table 1, the composite sheets of Examples had better bending strength after firing and higher thermal conductivity after firing than the composite sheets of Comparative Examples.

[0290] If the bending strength after firing is good, it can also show resistance to the shock wave from the explosion when the high energy density battery runs out of control. In addition, if the thermal conductivity after firing is high, the heat generated by contact with the flame can be effectively transferred to the opposite side of the contact with the flame surface, and the temperature rise on the back side of the contact with the flame surface can be suppressed by heat dissipation.

[0291] Industrial Applicability

[0292] As described above, the composite sheet of the present invention has high flame shielding and combustion resistance, and is low in density and excellent in lightness. Therefore, it is useful as a material for various industrial parts requiring high safety, such as aircraft, ships, automobile parts, electrical and electronic equipment parts, and building materials. In particular, it can be suitably used in various housings and frames of batteries that have conventionally used metals, contributing to the safety of automobiles, and it can be expected that the lightweighting will lead to improved energy efficiency, CO 2 Reduction of emissions, etc.

[0293] The composite sheet of the present invention has excellent flame barrier properties, and because it is mainly composed of resin, it has excellent processability and is lightweight. Therefore, a structure using the composite sheet of the present invention is useful as an electric vehicle.

Claims

1. A composite sheet comprising a thermoplastic resin composition (X) and an inorganic fiber (Y), The thermoplastic resin composition (X) comprises a thermoplastic resin and a heat-expandable flame retardant, The density of the composite sheet is 1.3 g / cm 3 the following.

2. The composite sheet according to claim 1, in, When observing the cut surface of the composite sheet, there are multiple cross-sectional areas of 0.01mm 2 The pores above have a cross-sectional area of ​​0.01 mm 2 The average cross-sectional area of ​​the above pores is 0.03 mm 2 Above and 0.8mm 2 the following. 3 . The composite sheet according to claim 1 , wherein a thickness ratio before and after heating at 1200° C. for 15 minutes (thickness after high temperature test / thickness before high temperature test) is 5 times or less. 4 . The composite sheet according to claim 1 , comprising a surface sheet comprising a nonwoven fabric formed of resin fibers.

5. The composite sheet according to claim 1, in, The heat-expandable flame retardant includes a phosphorus-based flame retardant.

6. The composite sheet according to claim 1 or 4, in, The thermoplastic resin constituting the thermoplastic resin composition (X) includes a polyolefin resin.

7. The composite sheet according to claim 1, in, The thermoplastic resin composition (X) further comprises a dispersant.

8. The composite sheet according to claim 7, in, The dispersant includes a copolymer of an α-olefin and an unsaturated carboxylic acid.

9. The composite sheet according to claim 7 or 8, in, The content of the dispersant is more than 0 and 25 parts by mass or less based on 100 parts by mass of the heat-expandable flame retardant.

10. The composite sheet according to claim 1 or 4, in, The inorganic fibers (Y) include at least one selected from the group consisting of glass fibers, ceramic fibers, metal fibers, and metal oxide fibers. 11 . The composite sheet according to claim 1 , wherein a mat composed of inorganic fibers (Y) is impregnated with the thermoplastic resin composition (X).

12. A method for producing a composite sheet according to claim 1 or 4, wherein the method include: A sheet composed of the thermoplastic resin composition (X) is stacked on a mat composed of the inorganic fibers (Y), and the mixture is heated and melted to impregnate the mat with the thermoplastic resin composition (X).

13. The method for producing a composite sheet according to claim 12, wherein include: The mat composed of the inorganic fibers (Y) is laminated so as to be located between two sheets composed of the thermoplastic resin composition (X).

14. A molded product obtained by molding the composite sheet according to claim 1 or 4. The molded body according to claim 14 , which is used for a battery housing.

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