Stampable sheet and molded article using the same

Abstract

To provide a stampable sheet that is superior in both flame shielding and heat insulation.SOLUTION: A stampable sheet contains a thermoplastic resin composition (X) and inorganic fiber (Y). The thermoplastic resin composition (X) contains a thermoplastic resin and a phosphorous flame retardant. The stampable sheet has an expansion ratio of 300% or more when heated at 1200°C for 5 minutes.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a stampable sheet and a molded article using the same. [Background technology]

[0002] In recent years, research and development of electric and hybrid vehicles has been progressing as part of environmental measures, and there has been a surge in the development and weight reduction of high-energy-density batteries aimed at improving driving range. Such high-energy-density batteries pose a risk of ignition in the event of an accident, and as a safety measure for passengers, their housing material needs to have high flame resistance, so metal materials such as iron are often used in combination with fire-resistant materials. However, metal materials have the disadvantage of being heavy, and when used in combination with fire-resistant materials, processability and increased costs due to the increased number of parts become challenges. Therefore, attempts are being made to use resins, which have the potential to achieve both lightness and flame resistance. Currently, in order to move towards a sustainable society, the reduction of carbon dioxide emissions and recyclability are becoming increasingly important. Thermosetting materials often have high flame retardancy and are common as composite materials, but thermoplastic resin materials have an advantage in terms of recyclability.

[0003] Furthermore, China has published a safety standard, GB 38031-2020, "Safety Requirements for Batteries for Electric Vehicles," which mandates that a warning be issued 5 minutes before battery thermal runaway occurs. However, this is believed to be achievable by using housing materials that provide flame protection for more than 5 minutes after the battery ignites.

[0004] To address these challenges, for example, Patent Document 1 proposes a carbon fiber-reinforced polypropylene resin to which brominated flame retardants or antimony oxide compounds have been added. However, the additives used in this invention have problems with their persistence in living organisms. In response to this, and taking into consideration biopersity, Patent Document 2 proposes a flame-retardant polyolefin composition containing a (poly)phosphate compound in a polyolefin resin as a technology for making polypropylene resins flame-retardant. Furthermore, Patent Document 3 proposes a flame-retardant resin composition containing glass long fibers and a phosphate compound in a polypropylene resin. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-62189 [Patent Document 2] Japanese Patent Publication No. 2013-119575 [Patent Document 3] Japanese Patent Publication No. 2011-88970 [Overview of the project] [Problems that the invention aims to solve]

[0006] Conventional fiber-reinforced composite material technology, which has the potential to achieve both weight reduction and flame resistance in high-energy-density batteries, has many shortcomings. Specifically, stampable sheets, which are the material for fiber-reinforced composite materials, require high flame resistance and further improvements in heat insulation.

[0007] This invention was made to solve the above-mentioned problems, and aims to provide a stampable sheet that combines high flame-retardant properties and heat-insulating properties. [Means for solving the problem]

[0008] The present inventors, in order to solve the above problems, conducted diligent research and found that a stampable sheet comprising a thermoplastic resin composition (X) and inorganic fibers (Y), wherein the thermoplastic resin composition (X) comprises a thermoplastic resin and a phosphorus-based flame retardant, and which has an expansion ratio of 300% or more when heated under specific conditions, can solve the above problems. Based on these findings, the present invention was completed. In other words, the present invention provides the following [1] to

[10] . [1] A stampable sheet comprising a thermoplastic resin composition (X) and an inorganic fiber (Y), wherein the thermoplastic resin composition (X) comprises a thermoplastic resin and a phosphorus-based flame retardant, and its expansion ratio when heated at 1200°C for 5 minutes is 300% or more. [2] The stampable sheet according to [1] above, wherein the inorganic fiber (Y) is an inorganic fiber nonwoven fabric. [3] The stampable sheet according to [2] above, wherein the needle penetration depth of the inorganic fiber nonwoven fabric is 15 mm or more. [4] The stampable sheet according to any one of [1] to [3] above, wherein the thermoplastic resin constituting the thermoplastic resin composition (X) is a polyolefin resin. [5] The stampable sheet according to any one of [1] to [4] above, wherein the thermoplastic resin composition (X) further comprises a dispersant. [6] The stampable sheet according to [5], wherein the dispersant is a copolymer of an α-olefin and an unsaturated carboxylic acid. [7] The stampable sheet according to [5] or [6] above, wherein the content of the dispersant per 100 parts by mass of the phosphorus-based flame retardant is greater than 0 and less than or equal to 25 parts by mass. [8] The stampable sheet according to any one of [1] to [7] above, wherein the inorganic fiber (Y) is at least one selected from glass fiber, ceramic fiber, metal fiber and metal oxide fiber. [9] The stampable sheet according to any one of [1] to [8] above, wherein the content of the phosphorus-based flame retardant is 1 to 30% by mass with respect to the total weight.

[10] A molded body obtained by stamping a stampable sheet as described in any of [1] to [9] above. [Effects of the Invention]

[0009] According to the present invention, a stampable sheet can be provided that combines high flame-retardant properties with high heat-insulating properties. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing the structure and manufacturing method of the stampable sheet of the present invention. [Figure 2] It is a schematic diagram showing the structure and manufacturing method of the stampable sheet of the present invention.

[0011] Hereinafter, embodiments of the present invention will be described in detail. However, the following description is an example of an embodiment of the present invention, and the present invention is not limited to these contents at all.

[0012] [Stampable Sheet] The stampable sheet of the present invention contains a thermoplastic resin composition (X) and inorganic fibers (Y). The thermoplastic resin composition (X) contains a thermoplastic resin and a phosphorus-based flame retardant. Further, it is characterized in that the expansion ratio (hereinafter sometimes simply referred to as "expansion ratio") when heated at 1200 °C for 5 minutes is 300% or more. Since the expansion ratio is high, it becomes easy to form a char by the phosphorus-based flame retardant contained in the thermoplastic resin composition (X) in the gap space of the inorganic fibers Y generated by the expansion. On the other hand, since the formed char is fixed in the gaps of the inorganic fibers, the formation of a dense char is promoted. Thereby, the effects of high flame shielding property and heat insulation property are exhibited. By the expansion ratio of the stampable sheet of the present invention being 300% or more, a stampable sheet excellent in flame shielding property and heat insulation property can be obtained. The stampable sheet of the present invention only needs to have an expansion ratio of 300% or more. However, from the viewpoint of exhibiting higher levels of flame shielding property and heat insulation property, the expansion ratio is preferably 310% or more, and more preferably 320% or more. On the other hand, from the viewpoint of ensuring sufficient strength, the expansion ratio is preferably 1000% or less, and more preferably 800% or less.

[0013] As a specific embodiment, for example, a stampable sheet having a layer in which a thermoplastic resin composition (X) and an inorganic fiber nonwoven fabric are integrated can be mentioned. As an example of a preferred embodiment, a stampable sheet having a depth of 15 mm or more of the needles of the inorganic fiber nonwoven fabric can be mentioned. When the depth of the needles is 15 mm or more, the expansion due to springback when the stampable sheet is heated becomes larger, and the flame shielding property and heat insulating property of the stampable sheet can be improved. From the same viewpoint, the depth of the needles of the inorganic fiber nonwoven fabric is preferably 15 mm or more. On the other hand, from the viewpoint of productivity, it is preferably 20 mm or less, more preferably 18 mm or less.

[0014] As another example of a preferred embodiment, a stampable sheet having a layer in which a thermoplastic resin composition (X) and three or more inorganic fiber nonwoven fabrics are integrated can be mentioned. When there are three or more inorganic fiber nonwoven fabrics, the expansion due to springback when the stampable sheet is heated becomes larger, and the flame shielding property and heat insulating property of the stampable sheet can be improved. From the same viewpoint, the number of inorganic fiber nonwoven fabrics can be four or more, or five or more. On the other hand, from the viewpoint of productivity, it is preferably 10 or less, more preferably 8 or less.

[0015] [Thermoplastic resin composition (X)] The thermoplastic resin composition (X) according to the present invention contains at least (a) a thermoplastic resin and (b) a phosphorus-based flame retardant. Hereinafter, (a) the thermoplastic resin and (b) the phosphorus-based flame retardant will be described in detail.

[0016] <(a) Thermoplastic resin> The thermoplastic resin used in the stampable sheet 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, modified polyphenylene oxides, and the like. These may be used alone or in combination of two or more. For example, the thermoplastic resin (a) may be a composite resin of two or more of the above thermoplastic resins.

[0017] There are no particular restrictions on the polyolefin resin, and examples include those described below. There are no particular restrictions on the polyester resin, and examples include polybutylene terephthalate. There are no particular restrictions on the polyamide resin, and examples include nylon 66 and nylon 6. In particular, the present invention is especially useful when (a) the thermoplastic resin includes at least a polyolefin resin. In this invention, "polyolefin resin" means a resin in which the proportion of olefin units or cycloolefin units is 90 mol% or more of the total constituent units of the resin. The proportion of olefin units or cycloolefin units relative to 100 mol% of all constituent units of the polyolefin resin is preferably 95 mol% or more, and particularly preferably 98 mol% or more.

[0018] Examples of polyolefin resins include α-olefin polymers such as polyethylene, polypropylene, polybutene, poly(3-methyl-1-butene), poly(3-methyl-1-pentene), and poly(4-methyl-1-pentene); α-olefin copolymers such as ethylene-propylene blocks or random copolymers, α-olefin-propylene blocks or random copolymers having 4 or more carbon atoms, ethylene-methyl methacrylate copolymers, and ethylene-vinyl acetate copolymers; and cycloolefin polymers such as polycyclohexene and polycyclopentene. 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. In α-olefin-propylene blocks or random copolymers having 4 or more carbon atoms, examples of α-olefins having 4 or more carbon atoms include butene, 3-methyl-1-butene, 3-methyl-1-pentene, and 4-methyl-1-pentene. These polyolefin resins may be used individually or in combination of two or more types. Of the olefin resins mentioned above, polypropylene resin (hereinafter sometimes referred to as "PP resin") is particularly preferred.

[0019] (Melt Flow Rate (MFR)) In the present invention, the melt flow rate (hereinafter sometimes abbreviated as MFR) (230°C, 2.16 kg load) of the thermoplastic resin (a) is preferably 40 to 500 g / 10 min. When the MFR is 40 g / 10 min or more, no defects occur when stamping the stampable sheet, and the processability does not decrease. When the MFR is 500 g / 10 min or less, no burrs are generated in the manufacture of the stampable sheet. From these viewpoints, the MFR is preferably 50 to 400 g / 10 min, more preferably 60 to 400 g / 10 min, and more preferably 70 to 300 g / 10 min. (a) The MFR of thermoplastic resins can be adjusted, for example, by controlling the hydrogen concentration during polymerization. Note that the MFR value was measured in accordance with JIS K7210.

[0020] (a) Thermoplastic resin content) (a) The content of the thermoplastic resin in the stampable sheet of the present invention is not particularly limited, but is preferably 15 to 80% by mass. When the thermoplastic resin content is 15% by mass or more, the moldability is particularly good, and the stampable sheet is easy to mold. On the other hand, when it is 80% by mass or less, a sufficient amount of flame retardant, dispersant and inorganic fiber can be included, and good flame resistance can be obtained. From the above viewpoint, the thermoplastic resin content in the stampable sheet is preferably 35 to 70% by mass, and more preferably 40 to 60% by mass.

[0021] <(a-1) Polypropylene resin> The thermoplastic resin used in the stampable sheet of the present invention preferably includes a polypropylene-based resin. Examples of polypropylene-based resins include propylene homopolymers or propylene-α-olefin copolymers. Here, the propylene-α-olefin copolymer may be either a random copolymer or a block copolymer.

[0022] (α-olefin) Examples of α-olefins constituting the above copolymer include ethylene, 1-butene, 2-methyl-1-propene, 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, and 1-octene. These may be copolymerized with propylene using one type, or with propylene using two or more types. Among these, ethylene or 1-butene are preferred from the viewpoint of improving the impact strength of the stampable sheet, and ethylene is the most preferred.

[0023] (Propylene-ethylene random copolymer) In the case of a random copolymer of propylene and ethylene, it preferably contains 90 to 99.5% by mass of propylene units, more preferably 92 to 99% by mass, and 0.5 to 10% by mass of ethylene units, more preferably 1 to 8% by mass. If the amount of ethylene units is above the lower limit, sufficient impact strength of the stampable sheet is obtained, and if it is below the upper limit, sufficient rigidity is maintained. The content of propylene units and ethylene units in a random copolymer of propylene and ethylene can be adjusted by controlling the composition ratio of propylene and ethylene during polymerization of the random copolymer. Furthermore, the propylene content of a random copolymer of propylene and ethylene is a value measured using a cross-fractionation device or FT-IR, and the measurement conditions can be, for example, those described in Japanese Patent Publication No. 2008-189893.

[0024] (Melt Flow Rate (MFR)) The melt flow rate (hereinafter sometimes abbreviated as 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 min. If the MFR is 40 g / 10 min or more, no defects will occur when stamping the stampable sheet, and the processability will not decrease. If the MFR is 500 g / 10 min or less, no burrs will be generated in the manufacture of the stampable sheet. From these viewpoints, the MFR is preferably 50 to 400 g / 10 min, more preferably 60 to 400 g / 10 min, and more preferably 70 to 300 g / 10 min. (A-1) Polypropylene resins (propylene homopolymers) can have their MFR adjusted by controlling the hydrogen concentration during polymerization. Note that the MFR value was measured in accordance with JIS K7210.

[0025] ((a-1) Polypropylene resin content) The content of (a-1) polypropylene resin in the stampable sheet of the present invention is not particularly limited, but is preferably 15 to 80% by mass. When the polypropylene resin content is 15% by mass or more, the moldability is sufficient, and the stampable sheet is easy to mold. On the other hand, when it is 80% by mass or less, the content of flame retardants, dispersants and inorganic fibers becomes insufficient, and sufficient flame resistance cannot be obtained. From the above viewpoint, the polypropylene resin content in the stampable sheet is more preferably 35 to 70% by mass, and even more preferably 40 to 60% by mass.

[0026] <Modified polyolefin resin> The stampable sheet of the present invention may further contain a modified polyolefin resin in addition to the polypropylene resin described above. Specifically, examples of modified polyolefin resins include acid-modified polyolefin resins and hydroxy-modified polyolefin resins, which can be used individually or in combination. Furthermore, there are no particular restrictions on the types of acid-modified polyolefin resins and hydroxy-modified polyolefin resins used as modified polyolefin resins; conventionally known resins may be used.

[0027] (Acid-modified polyolefin resin) Examples of acid-modified polyolefin resins include those obtained by graft copolymerizing polyolefins such as polyethylene, polypropylene, ethylene-α-olefin copolymers, ethylene-α-olefin-non-conjugated diene compound copolymers (such as EPDM), and ethylene-aromatic monovinyl compound-conjugated diene compound copolymer elastomers using an unsaturated carboxylic acid such as maleic acid or maleic anhydride, thereby chemical modification. This graft copolymerization is carried out, for example, by reacting the above-mentioned polyolefin with an unsaturated carboxylic acid in a suitable solvent using a radical generator such as benzoyl peroxide. Alternatively, the unsaturated carboxylic acid or its derivative can be introduced into the polymer chain by random or block copolymerization with a monomer for polyolefins.

[0028] Examples of unsaturated carboxylic acids used for modification include compounds having polymerizable double bonds into which carboxyl groups and, if necessary, functional groups such as hydroxyl groups or amino groups have been introduced, such as maleic acid, fumaric acid, itaconic acid, acrylic acid, and methacrylic acid. Furthermore, derivatives of unsaturated carboxylic acids include their acid anhydrides, esters, amides, imides, and metal salts. Specific examples include maleic anhydride, itaconic anhydride, methyl acrylate, ethyl acrylate, butyl acrylate, and methyl methacrylate. Of these, maleic anhydride is preferred.

[0029] Preferred acid-modified polyolefin resins include those obtained by graft polymerization of maleic anhydride onto an olefin polymer whose main polymer constituent units are ethylene and / or propylene, and those obtained by copolymerizing an olefin mainly composed of ethylene and / or propylene with maleic anhydride. Specifically, examples include combinations of polyethylene / maleic anhydride-grafted ethylene-butene-1 copolymer, or polypropylene / maleic anhydride-grafted polypropylene.

[0030] (Hydroxy-modified polyolefin resin) Hydroxyl-modified polyolefin resins are modified polyolefin resins that contain hydroxyl groups. Hydroxyl-modified polyolefin resins may have hydroxyl groups at appropriate locations, for example, at the ends of the main chain or in side chains. Examples of olefin resins constituting hydroxy-modified polyolefin resins include α-olefins alone or copolymers such as ethylene, propylene, butene, 4-methylpentene-1, hexene, octene, nonene, decene, and dodecene, as well as copolymers of the α-olefins with copolymerizable monomers. Examples of preferred hydroxy-modified polyolefin resins include hydroxy-modified polyethylene resins such as low-density, medium-density, or high-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, ethylene-(meth)acrylic acid ester copolymers, and ethylene-vinyl acetate copolymers; polypropylene homopolymers such as isotactic polypropylene; random copolymers of propylene and α-olefins (e.g., ethylene, butene, hexane, etc.); propylene-α-olefin block copolymers; and hydroxy-modified polypropylene resins such as hydroxy-modified poly(4-methylpentene-1).

[0031] (b) Phosphorus-based flame retardants The fiber-reinforced resin composite material of the present invention contains (b) a phosphorus-based flame retardant. Phosphorus-based flame retardants are preferred from the viewpoint of improving flame resistance, having no biological residue, and possessing excellent flame retardancy. In the present invention, a phosphorus-based flame retardant is essential, but other flame retardants may be used in combination, specifically bromine-based flame retardants, antimony-based flame retardants, etc. Furthermore, in terms of classification focusing on the mechanism of action of flame retardants, (b) the flame retardant is preferably an intomessecent flame retardant from the viewpoint of improving flame resistance.

[0032] Phosphorus-based flame retardants are phosphorus compounds, that is, compounds containing phosphorus atoms in their molecules. Phosphorus-based flame retardants exert their flame-retardant effect by causing char to form during the combustion of resin compositions. Phosphorus-based flame retardants may be any known type, such as (poly)phosphates and (poly)phosphate esters. Here, "(poly)phosphate" refers to a phosphate or polyphosphate, and "(poly)phosphate ester" refers to a phosphate ester or polyphosphate ester. Furthermore, it is preferable that the phosphorus-based flame retardant is solid at 80°C.

[0033] As a phosphorus-based flame retardant, (poly)phosphates are preferred in terms of flame retardancy. Examples of (poly)phosphates include ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, piperazine orthophosphate, melamine pyrophosphate, piperazine pyrophosphate, melamine polyphosphate, melamine orthophosphate, calcium phosphate, and magnesium phosphate. Furthermore, compounds in which melamine or piperazine is replaced with other nitrogen compounds in the above examples can also be used. 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-propanediamine, 1,3-propanediamine, tetramethyl Diadiamine, 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, acrylicguanamine, 2,4-diamino-6-nonyl-1,3,5-triamine Zin, 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, Examples include 3,5-triazine, 2-amino-4,6-dimercapto-1,3,5-triazine, ammeline, benzguanamine, acetoguanamine, phthalodiguanamine, melamine cyanurate, melamine pyrophosphate, butylenediguanamine, norbornenediguanamine, methylenediguanamine, ethylenedimelamine, trimethylenedimelamine, tetramethylenedimelamine, hexamethylenedimelamine, and 1,3-hexylenedimelamine. These (poly)phosphates may be used individually or in combination of two or more.

[0034] Among the phosphorus-based flame retardants mentioned above, a salt of (poly)phosphoric acid and a nitrogen compound (hereinafter also referred to as "compound (b1)") is preferred. Compound (b1) is an intomessent flame retardant that forms a foamed char surface expansion layer (intomescent) when the resin composition is burned. The formation of the surface expansion layer suppresses the diffusion of decomposition products and heat transfer, resulting in excellent flame retardancy. Examples of nitrogen compounds in compound (b1) include ammonia, melamine, piperazine, and the other nitrogen compounds mentioned above.

[0035] Examples of commercially available phosphorus-based flame retardants include ADEKA FP-2100J, FP-2200, and FP-2500S (manufactured by ADEKA Corporation).

[0036] (Bromine-based flame retardant) Examples of brominated flame retardants 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, Examples include brominated polystyrene, ethylene bistetrabromophthalimide, 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.

[0037] (Antimony-based flame retardant) Examples of antimony-based flame retardants include antimony trioxide, antimony tetroxide, antimony pentoxide, sodium pyroantimonate, antimony trichloride, antimony trisulfide, antimony oxychloride, antimony perchloropentane dichloride, and potassium antimonate, with antimony trioxide and antimony pentoxide being particularly preferred.

[0038] (Intomessent flame retardant) Intomescent flame retardants are flame retardants that suppress the combustion of materials by forming an intumescent surface expansion layer that prevents radiant heat from the combustion source and the diffusion of combustion gases and smoke from the burning material to the outside. Examples of intomescent flame retardants include salts of (poly)phosphate and nitrogen compounds. Specifically, examples include ammonium salts and amine salts of (poly)phosphate such as ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, ammonium pyrophosphate, melamine pyrophosphate, and piperazine pyrophosphate.

[0039] Of the above flame retardants, non-halogen flame retardants are preferred from an environmental standpoint. Furthermore, intomescent flame retardants are preferred from the viewpoint of improving the flame-retardant properties of the resulting stampable sheet. Furthermore, the above-mentioned flame retardants can be used individually or in combination of two or more types.

[0040] ((b) Content of phosphorus-based flame retardants) The content of the phosphorus-based flame retardant in the stampable sheet of the present invention is not particularly limited, but is preferably in the range of 1 to 30% by mass in the thermoplastic resin composition (X). If it is 1% by mass or more, good flame retardancy can be imparted to the stampable sheet, and good flame shielding properties can be obtained. On the other hand, if the flame retardant is 30% by mass or less, the thermoplastic resin can be included in a sufficient proportion, so the moldability is better. From the above viewpoint, the content of the flame retardant in the thermoplastic resin composition (X) is more preferably in the range of 1 to 25% by mass, and even more preferably in the range of 3 to 20% by mass.

[0041] (c) Dispersant (c) The dispersant is not particularly limited as long as it can disperse (b) the phosphorus-based flame retardant in (a) the thermoplastic resin, but a polymer dispersant can be suitably used in terms of compatibility with (a) the thermoplastic resin. Preferably, one that can disperse (b) the phosphorus-based flame retardant in (a-1) the polypropylene resin can be suitably used. A polymer dispersant having a functional group is preferred, and from the viewpoint of dispersion stability, a polymer dispersant having a functional group such as a carboxyl group, a phosphate group, a sulfonic acid group, a primary, secondary or tertiary amino group, a quaternary ammonium base, a nitrogen-containing heterocycle-derived group such as pyridine, pyrimidine, or pyrazine is preferred. In the present invention, polymeric dispersants having carboxyl groups are preferred, and in particular, when using phosphorus-based flame retardants suitable as flame retardants, copolymers of α-olefins and unsaturated carboxylic acids are preferred. By using such dispersants, the dispersibility of phosphorus-based flame retardants can be improved, and the content of the flame retardant can be reduced.

[0042] (Copolymer of α-olefin and unsaturated carboxylic acid) In the "polymer of α-olefin and unsaturated carboxylic acid" according to the present invention (hereinafter referred to as "polymer (c1)"), it is preferable that the proportion of α-olefin units in the total 100 mol% of α-olefin units and unsaturated carboxylic acid units is 20 mol% or more and 80 mol% or less. In copolymer (c1), the ratio of α-olefin units to the total amount of α-olefin units and unsaturated carboxylic acid units is more preferably 30 mol% or more, while it is more preferably 70 mol% or less. If the ratio of α-olefin is above the lower limit, (a) compatibility with polyolefin resins is improved, and if it is below the upper limit, (b) compatibility with phosphorus-based flame retardants is improved.

[0043] In copolymer (c1), α-olefins having 5 or more carbon atoms are preferred, and α-olefins having 10 to 80 carbon atoms are more preferred. If the α-olefin has 5 or more carbon atoms, (a) compatibility with thermoplastic resins tends to be better, and if it has 80 or fewer carbon atoms, it is advantageous in terms of raw material costs. From the above viewpoint, it is even more preferable that the α-olefin has 12 to 70 carbon atoms, and particularly preferable that it has 18 to 60 carbon atoms.

[0044] Furthermore, in copolymer (c1), examples of unsaturated carboxylic acids include (meth)acrylic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, glutaconic acid, norbornane-5-ene-2,3-dicarboxylic acid, and esters, anhydrides, and imides of these unsaturated carboxylic acids. Note that "(meth)acrylic acid" refers to acrylic acid or methacrylic acid. Specific examples of esters, anhydrides, or imides of unsaturated carboxylic acids include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and glycidyl (meth)acrylate; dicarboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic acid anhydride; and maleimide compounds such as maleimide, N-ethylmaleimide, and N-phenylmaleimide. These may be used individually or in combination of two or more. Among the above, esters and dicarboxylic acid anhydrides are preferred from the viewpoint of copolymerization reactivity. In particular, dicarboxylic acid anhydrides are preferred from the viewpoint of compatibility with phosphorus-based flame retardants which are suitable as flame retardants, and maleic anhydride is especially preferred.

[0045] The weight-average molecular weight of copolymer (c1) is preferably 2,000 or more, more preferably 3,000 or more, while it is preferably 50,000 or less, and more preferably 30,000 or less. If the weight-average molecular weight of copolymer (c1) is within the above range, the dispersibility of (b) the flame retardant will be better. The weight-average molecular weight of copolymer (c1) is a value on a standard polystyrene basis, measured by gel permeation chromatography after dissolving copolymer (c1) in tetrahydrofuran (THF).

[0046] Examples of commercially available copolymers (c1) include Recolb CE2 (manufactured by Clariant Japan Co., Ltd.) and Diacarna 30M (manufactured by Mitsubishi Chemical Corporation).

[0047] The content of (c) dispersant in this stampable sheet relative to (b) phosphorus-based flame retardant per 100 parts by mass is greater than 0 and less than or equal to 25 parts by mass, preferably in the range of 0.01 to 10 parts by mass. According to the inventors' research, the flame retardant can be significantly improved when a flame retardant is uniformly dispersed in the inorganic fibers constituting the stampable sheet using a thermoplastic resin as the matrix resin. Although the detailed mechanism is unknown, the inventors speculate as follows: When the flame retardant is uniformly dispersed in the resin between the inorganic fibers, the char formed when the phosphorus-based flame retardant comes into contact with flame is fixed in the gaps between the inorganic fibers. Furthermore, the gaps between the inorganic fibers limit the size of the char that expands and is formed when it comes into contact with flame, resulting in a uniform size of the formed char. The inventors believe that the combination of the char fixing effect by the inorganic fibers and the uniformity of char size results in the formation of a dense char, significantly improving the flame retardant of the stampable sheet. Based on these findings, the inventors have discovered that by controlling the ratio of the dispersant content to the flame retardant within a specific range, the flame retardant can be uniformly distributed in the resin between the inorganic fibers, thereby significantly improving the flame retardant of the stampable sheet. For the reasons stated above, if the content of (c) dispersant is greater than 0, the dispersibility of (b) phosphorus-based flame retardant becomes sufficient, and sufficient flame-retardant properties cannot be imparted to the stampable sheet. On the other hand, if the content is 25 parts by mass or less, the physical properties of the stampable sheet become sufficient. From a similar viewpoint, the content of (c) dispersant is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 2 parts by mass or more. On the other hand, the upper limit is more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less.

[0048] Furthermore, the ratio of (c) dispersant to 100 parts by mass of the total of (a) thermoplastic resin and (b) phosphorus-based flame retardant is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more 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, even more preferably 2.0 parts by mass or less, even more preferably 1.5 parts by mass or less, and even more preferably 1.0 part by mass or less. If the ratio of (c) dispersant is above the lower limit, the (b) phosphorus-based flame retardant will be dispersed more well, resulting in better flame resistance and physical properties of the resulting stampable sheet and better appearance of the resulting molded article. If the ratio of (c) dispersant is below the upper limit, the influence of (c) dispersant on the flame resistance of the stampable sheet can be further suppressed. In particular, the ratio of (c) dispersant to 100 parts by mass of the total of the polyolefin resin and (b) phosphorus-based flame retardant is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more 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, even more preferably 2.0 parts by mass or less, even more preferably 1.5 parts by mass or less, and even more preferably 1.0 part by mass or less.

[0049] Furthermore, for the inorganic fibers (Y) described in detail below, the ratio of the dispersant (c) to 100 parts by mass of the inorganic fibers (Y) is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more 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 even more preferably 2.0 parts by mass or less. If the ratio of the dispersant (c) is above the lower limit, the flame resistance and physical properties of the resulting stampable sheet and the appearance of the resulting molded article will be better. If the ratio of the dispersant (c) is below the upper limit, the influence of the dispersant (c) on the flame resistance of the stampable sheet can be further suppressed.

[0050] <(Y) Inorganic Fibers> The stampable sheet of the present invention contains (Y) inorganic fibers. Various types of fibers can be used as (Y) inorganic fibers, for example, metal oxide fibers such as glass fibers, rock wool, alumina fibers, silica alumina fibers, ceramic fibers such as potassium titanate fibers, calcium silicate (wollastonite) fibers, and ceramic fibers, carbon fibers, and metal fibers. These inorganic fibers may be used individually or in combination of two or more types. Of the inorganic fibers mentioned above, at least one selected from glass fibers and alumina fibers is preferred from the viewpoint of flame resistance and processability. (Y) The inorganic fiber may include two or more inorganic fibers with different melting temperatures. Preferably, the combination of two or more inorganic fibers with different melting temperatures includes at least one glass fiber and one or more other inorganic fibers selected from the group consisting of alumina fiber, silica fiber, alkali earth silicate fiber (biosoluble), and carbon fiber. Including two or more inorganic fibers with different melting temperatures effectively prevents a decrease in flame-retardant function. Furthermore, the inorganic fibers used in the present invention may be used in combination with a consolidating agent or a surface treatment agent. Examples of such consolidating agents or surface treatment agents include compounds having functional groups such as epoxy compounds, silane compounds, and titanate compounds.

[0051] The average fiber diameter of the inorganic fibers is preferably 3 to 25 μm. Furthermore, fiber diameter can be measured using a scanning electron microscope, and the average fiber diameter can be obtained, for example, by measuring the fiber diameter of 10 randomly selected fibers and calculating the average value.

[0052] The average fiber length is preferably 30 mm or more, more preferably 40 mm or more, and even more preferably 50 mm or more. When the average fiber length is 30 mm or more, the resin components are easily constrained by the continuous long fibers, making it easy to form a dense char. Therefore, the stampable sheet of the present invention can obtain excellent flame resistance. Furthermore, fiber length can be measured using a ruler, calipers, etc., from magnified images obtained with a microscope, etc., as needed. The average fiber length can be obtained, for example, by measuring the fiber length of 10 randomly selected fibers and calculating the average value.

[0053] The inorganic fiber content in the stampable sheet of the present invention is 1 to 80% by mass overall. When the inorganic fiber content is 1% by mass or more, the strength, rigidity, and impact resistance of the stampable sheet are sufficient, and when it is 80% by mass or less, it is preferable in terms of manufacturing and processing the stampable sheet. Furthermore, when the inorganic fiber content is 80% by mass or less, the specific gravity of the stampable sheet becomes lighter, and the weight reduction effect as a metal substitute becomes significant. From the above perspective, the content of (Y) inorganic fibers in the stampable sheet is more preferably 3 to 60% by mass, even more preferably 10 to 50% by mass, and particularly preferably 30 to 45% by mass.

[0054] (Glass fiber) Glass fiber is one of the inorganic fibers (Y) suitable for the stampable sheet of the present invention. The glass fiber may be, for example, a long fiber with an average fiber length of 30 mm or more, or a short fiber (chopped strand) with an average fiber length, but it is preferable to use glass fiber with a long average fiber length from the viewpoint of flame resistance, rigidity, impact resistance, etc.

[0055] Furthermore, the average fiber diameter of the glass fibers is preferably in the range of 9 to 25 μm. If the average fiber diameter is 9 μm or more, the rigidity and impact resistance of the stampable sheet will be sufficient, while if the average fiber diameter is 25 μm or less, the strength of the stampable sheet will be good. From the above viewpoint, it is even more preferable that the average fiber diameter of the glass fibers is in the range of 10 to 15 μm. The average fiber diameter and average fiber length of glass fibers can be measured using the method described above.

[0056] There are no special restrictions on the material of the glass fiber used in this invention; it may be alkali-free glass, low-alkali glass, or alkali-containing glass, and various compositions that have been conventionally used as glass fibers can be used.

[0057] (Alumina fiber) Alumina fiber is one of the inorganic fibers (D) suitable for the stampable sheet of the present invention. Alumina fiber is a fiber that is usually composed of alumina and silica, and in the stampable sheet of the present invention, the alumina / silica composition ratio (mass ratio) of the alumina fiber is preferably in the range of 65 / 35 to 98 / 2, which is called a mullite composition or 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.

[0058] The average fiber diameter of the alumina fibers is preferably in the range of 3 to 25 μm, and it is preferable that the fibers substantially do not contain fibers with a fiber diameter of 3 μm or less. Here, "substantially free of fibers with a fiber diameter of 3 μm or less" means that the amount of fibers with a fiber diameter of 3 μm or less is 0.1% by mass or less of the total inorganic fiber mass. Furthermore, it is more preferable that the average fiber diameter of the alumina fibers be 5 to 8 μm. If the average fiber diameter of the inorganic fibers is too thick, the resilience and toughness of the mat-like inorganic fiber aggregate layer will decrease, and conversely, if it is too thin, the amount of dust that floats in the air will increase, and the probability of containing inorganic fibers with a fiber diameter of 3 μm or less will increase.

[0059] (Carbon fiber) The range of suitable applications for carbon fiber is similar to that of glass fiber.

[0060] <Optional addition ingredients> In addition to the above-mentioned components, the stampable sheet of the present invention may contain any additional components to enhance the effects of the invention, or to impart other effects, to the extent that they do not significantly impair the effects of the present invention. Specifically, examples include colorants such as 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 and antifungal agents such as thiazoles, flame retardants and flame retardant aids such as halogen compounds and lignophenols, plasticizers, dispersants such as organometallic salts, lubricants such as fatty acid amides, metal deactivators such as nitrogen compounds, polyolefin resins other than the aforementioned polypropylene resins, thermoplastic resins such as polyamide resins and polyester resins, elastomers (rubber components) such as olefin elastomers and styrene elastomers. Two or more of these optional additives may be used in combination.

[0061] As colorants, inorganic and organic pigments, for example, are effective in imparting and improving the colored appearance, aesthetics, texture, commercial value, weather resistance, and durability of polypropylene resin compositions and their molded articles. Specific examples of inorganic pigments include carbon black such as furnace carbon and Ketjencarbon; titanium dioxide; iron oxide (such as red iron oxide); chromic acid (such as yellow lead); molybdic acid; selenides sulfides; and ferrocyanides. Organic pigments include azo pigments such as sparingly soluble azo lakes, soluble azo lakes, insoluble azo chelates, condensing azo chelates, and other azo chelates; phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; slene pigments such as anthraquinone, perinone, perylene, and thioindigo; dye lakes; quinacridone-based pigments; dioxazine-based pigments; and isoindolinone-based pigments. In addition, aluminum flakes and pearl pigments can be included to create metallic or pearlescent finishes. Dyes can also be included.

[0062] For example, hindered amine compounds, benzotriazole compounds, benzophenone compounds, and salicylate compounds are effective as light stabilizers and ultraviolet absorbers in providing and improving the weather resistance and durability of polypropylene resin compositions and their molded articles, and are also effective in further improving weather resistance and discoloration. Specific examples of hindered amine compounds include the condensate 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]]; tetrakis(2,2,6,6-tetramethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate; tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate; bis(1,2,2,6,6-pentame Examples of benzotriazoles include 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole and 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole. Examples of benzophenones include 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-octoxybenzophenone. Examples of salicylates include 4-t-butylphenyl salicylate and 2,4-di-t-butylphenyl 3',5'-di-t-butyl-4'-hydroxybenzoate. In this context, the method of using the light stabilizer and the ultraviolet absorber in combination is highly preferable due to its significant improvement in weather resistance, durability, and resistance to weather-induced discoloration.

[0063] For example, antioxidants such as phenolic, phosphorus-based, and sulfur-based antioxidants are effective in imparting and improving the heat resistance, processing stability, and heat aging resistance of polypropylene resin compositions and their molded articles. Furthermore, antistatic agents such as nonionic and cationic agents are effective in imparting and improving the antistatic properties of polypropylene resin compositions and their molded articles.

[0064] Examples of olefin-based elastomers include ethylene-α-olefin copolymer elastomers such as ethylene-propylene copolymer elastomer (EPR), ethylene-butene copolymer elastomer (EBR), ethylene-hexene copolymer elastomer (EHR), and ethylene-octene copolymer elastomer (EOR); ethylene-α-olefin-diene terpolymer elastomers such as ethylene-propylene-ethylidene norbornene copolymer, ethylene-propylene-butadiene copolymer, and ethylene-propylene-isoprene copolymer; and styrene-butadiene-styrene triblock copolymer elastomer (SBS). Examples of styrene-based elastomers include styrene-isoprene-styrene triblock copolymer elastomer (SIS), styrene-ethylene-butylene copolymer elastomer (SEB), styrene-ethylene-propylene copolymer elastomer (SEP), styrene-ethylene-butylene-styrene copolymer elastomer (SEBS), styrene-ethylene-butylene-ethylene copolymer elastomer (SEBC), hydrogenated styrene-butadiene elastomer (HSBR), styrene-ethylene-propylene-styrene copolymer elastomer (SEPS), styrene-ethylene-ethylene-propylene-styrene copolymer elastomer (SEEPS), styrene-butadiene-butylene-styrene copolymer elastomer (SBBS), partially hydrogenated styrene-isoprene-styrene copolymer elastomer, partially hydrogenated styrene-isoprene-butadiene-styrene copolymer elastomer, and hydrogenated polymer elastomers such as ethylene-ethylene-butylene-ethylene copolymer elastomer (CEBC). In particular, the use of ethylene-octene copolymer elastomer (EOR) and / or ethylene-butene copolymer elastomer (EBR) is preferred because it is easier to impart appropriate flexibility and other properties to the polypropylene resin composition and molded articles thereof of the present invention, and they tend to have excellent impact resistance.

[0065] <Method for producing thermoplastic resin composition (X)> The thermoplastic resin composition (X) according to the present invention, as described above, contains (a) a thermoplastic resin, a modified polyolefin resin which may be added as needed, (b) a phosphorus-based flame retardant, and (c) a dispersant which may be added as needed. In addition, optional additives may be included. In the above thermoplastic resin composition (X), if (a) the thermoplastic resin is (a-1) a polypropylene resin, it may be specifically referred to as a polypropylene resin composition (hereinafter sometimes referred to as "PP composition"). A conventionally known method can be used to produce the thermoplastic resin composition (X) or the PP composition, and it can be produced by blending, mixing, and melt-kneading the above components. Mixing is carried out using mixers such as tumblers, V-blenders, and ribbon blenders, and melt kneading is performed using equipment such as single-screw extruders, twin-screw extruders, Banbury mixers, roll mixers, Brabender plastographs, and kneaders, followed by melt kneading and granulation.

[0066] <Method for manufacturing stampable sheets> The stampable sheet of the present invention is not particularly limited in its manufacturing method, but preferably it is manufactured by impregnating a mat made of inorganic fibers (Y) (hereinafter sometimes referred to as "inorganic fiber mat (Y)") with the thermoplastic resin composition (X) or PP composition. Methods of impregnation include coating the inorganic fiber mat (Y) with the thermoplastic composition or PP composition, preparing a sheet of the thermoplastic resin composition or PP composition (hereinafter sometimes referred to as "thermoplastic resin sheet" or "PP sheet"), laminating the thermoplastic resin sheet or PP sheet onto the inorganic fiber mat, and impregnating it by heating and melting. In the present invention, from the viewpoint of the impregnation of the resin into the fibers of the stampable sheet, a method of laminating a thermoplastic resin sheet or PP sheet onto an inorganic fiber mat, heating, and melting is preferred. In particular, the inorganic fiber mat is laminated so that it is between two thermoplastic resin sheets or PP sheets, and then the laminate is heated and pressurized, and then cooled and solidified to obtain the stampable sheet. Here, there are no particular restrictions on the thickness of the thermoplastic resin sheet or PP sheet, as long as it is within a range that allows for good impregnation into the fiber mat.

[0067] (Inorganic fiber mat) There are no particular restrictions on the form of inorganic fibers used in the manufacturing method of stampable sheets, and various forms can be used, but those formed in the form of a mat or sheet are preferred. More specifically, mats formed from glass fibers (hereinafter referred to as "glass fiber mats") and mats formed from metal oxide fibers, such as alumina fibers (hereinafter referred to as "metal oxide mats") are preferred.

[0068] The basis weight (mass per unit area) of the inorganic fiber mat is not particularly limited and can be determined appropriately depending on the application, but is preferably 300 g / m². 2 More preferably 800 g / m² 2 Ultra-comfortable 1500g / m 2 It is superior. Furthermore, there are no particular restrictions on the basis weight of the inorganic fiber mat, but it is preferably 5000 g / m². 2 More preferably, 4500 g / m² 2 More preferably, 4000 g / m² 2 The following is particularly preferred: 3500 g / m² 2 The following applies:

[0069] The basis weight (weight per unit area) of the inorganic fiber mat can be set to the above range by adjusting the amount of fiber per unit area when the inorganic fiber aggregates constituting the inorganic fiber mat are laminated using a folding device. Furthermore, the inorganic fiber mat of the present invention may be composed of multiple inorganic fiber mats bonded together or as a single mat, but a single mat is preferable in terms of handling and peel strength at the adhesive interface.

[0070] (Glass fiber mat) Examples of glass fiber mats used in the present invention include felts and blankets processed from short-fiber glass cotton, chopped strand mats processed from continuous glass fibers, swirl mats of continuous glass fibers, and unidirectional aligned mats. Among these, using a glass fiber mat made by needle-punching a swirl mat of continuous glass fibers is particularly preferable because it provides excellent strength and impact resistance for the stampable sheet.

[0071] (Metal oxide fiber mat) The metal oxide fiber mat according to the present invention is a mat composed of metal oxide fibers such as alumina fibers and subjected to a needling treatment.

[0072] In a method of laminating a thermoplastic resin sheet or PP sheet onto an inorganic fiber mat and then 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, allowing the PP composition to be sufficiently impregnated into the inorganic fiber mat, resulting in a suitable stampable sheet. On the other hand, when the heating temperature is 300°C or lower, the thermoplastic resin composition or PP composition does not deteriorate. Furthermore, the pressurized pressure is preferably 0.1 to 1 MPa. When the pressurized pressure is 0.1 MPa or higher, the thermoplastic resin composition or PP composition can be sufficiently impregnated into the inorganic fiber mat, resulting in a suitable stampable sheet. On the other hand, when the pressure is 1 MPa or lower, the thermoplastic resin composition or PP composition flows, and no burrs are formed. Furthermore, while the cooling temperature is not particularly limited as long as it is below the freezing point of the thermoplastic resin in the thermoplastic resin composition or PP composition, a cooling temperature of 80°C or lower prevents deformation when removing the resulting stampable sheet. From this viewpoint, a cooling temperature of room temperature to 80°C is preferable.

[0073] Methods for obtaining a stampable sheet by heating, pressurizing, and cooling the above-mentioned laminate include press molding the laminate in a mold equipped with a heating device, and lamination, in which the laminate is heated and pressurized by passing it between two pairs of rollers equipped with heating devices. Lamination is particularly preferable because it allows for continuous production and thus has high productivity.

[0074] <Thickness of stampable sheet> The thickness of the stampable sheet of the present invention is typically 1 to 10 mm, preferably 2 to 5 mm. If the thickness of the stampable sheet is 1 mm or more, it is easy to manufacture. On the other hand, if the thickness of the stampable sheet is 10 mm or less, prolonged preheating is not required when processing the stampable sheet by stamping molding, and good moldability can be obtained.

[0075] <Molded body> The stampable sheet of the present invention can be molded into a desired shape by stamping it according to a conventional method, thereby obtaining a molded body made from the stampable sheet.

[0076] (Application) Applications of the stampable sheet of the present invention include, for example, various components in industrial fields such as automotive parts and electrical and electronic equipment components. In particular, because it has excellent strength, rigidity, conductivity, and processability, it can be suitably used in applications where these properties are balanced and highly required, such as various housings and enclosures such as battery cases.

[0077] <Textiles> The fibers in the fiber-reinforced resin according to the present invention may be organic or inorganic fibers, but inorganic fibers are preferred from the viewpoint of heat resistance. Examples include glass fibers, rock wool, basalt fibers, alumina fibers, silica-alumina fibers, potassium titanate fibers, calcium silicate (wollastonite) fibers, alkali earth silicate fibers (biosoluble), silica fibers, carbon fibers, etc. These inorganic fibers may be used individually or in combination of two or more types.

[0078] [Structure] The structure of the present invention comprises a battery housing and a battery cell. The battery housing of the present invention is as described in detail above. The structure in the present invention is preferably a battery, and is not particularly limited to any battery. Examples include secondary batteries such as lithium-ion batteries, nickel-metal hydride batteries, lithium-sulfur batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, sodium-sulfur batteries, lead-acid batteries, and air batteries. Among these, lithium-ion batteries are preferred, and in particular, the battery housing of the present invention is suitably used to suppress thermal runaway of lithium-ion batteries. That is, the battery housing of the present invention is preferably a battery housing for a lithium-ion battery.

[0079] [Electric Mobility] In this invention, electric mobility refers to transportation equipment such as vehicles, ships, and airplanes that operate using electricity as an energy source. Vehicles include not only electric vehicles (EVs) but also hybrid cars. The battery housing and battery cell structures of the present invention described above are highly safe and extremely useful for electric mobility devices that use battery modules with high energy density to extend driving range. [Examples]

[0080] The first aspect of the present invention will be described in detail below using examples, but the present invention is not limited to these examples. (Evaluation method) 1. Evaluation of flame resistance For each example and comparative example, the sheets prepared were evaluated by applying a 1300°C burner flame from one surface for 15 minutes and checking whether the flame penetrated the sheet. The distance from the burner nozzle to the sample was 160 mm. The flame surface temperature was set to 1200°C. The flame surface temperature was confirmed using a thermocouple thermometer.

[0081] 2. Evaluation of thermal insulation performance In the flame-retardant evaluation described in 1. above, the temperature of the back surface (opposite side) of the test specimen to the side exposed to the burner flame was measured using a non-contact infrared thermometer (Keyence FT-H50K). The measurement area was φ35 mm. The center of the measurement area was visually positioned so that it was approximately directly above the position of the burner flame. Table 1 shows the maximum temperature (°C) reached on the back surface after 120 seconds.

[0082] (Materials used) 1. Polypropylene resin (component a) We used "Novatec PP SA06GA" (melt flow rate: 60g / 10min) manufactured by Nippon Polypropylene Co., Ltd.

[0083] 2. Flame retardant (component b) Phosphorus-based flame retardant composition (Manufactured by ADEKA Corporation, ADEKA Stab FP-2500S, containing 50-60% by mass of piberazine pyrophosphate, 35-45% by mass of melamine pyrophosphate, and 3-6% by mass of zinc oxide, based on the total mass of the phosphorus-based flame retardant composition)

[0084] 3. Dispersant (component c) α-olefin / maleic anhydride copolymer (manufactured by Mitsubishi Chemical Corporation, Diacarna 30M, weight-average molecular weight 7,800).

[0085] 5. Glass fiber mat (component Y) (1) Glass fiber mat A Swirl mat (basis weight 880g / m²) manufactured from continuous glass fibers (fiber diameter 23μm) of roving. 2 A long-fiber glass fiber mat was used, which was needle-punched with a needle-punching depth set to 16.0 mm. (1) Glass fiber mat B A swirl (spiral) mat (basis weight 880 g / m 2 ) made from continuous glass fibers of roving (fiber diameter 23 μm) was needle punched at a needle punching depth of 14.6 mm to obtain a long fiber glass fiber mat, which was used.

[0086] Preparation Example 1 (Preparation of PP composition) Pellets of a polypropylene-based resin composition (PP composition) were prepared by melt kneading (at 230 °C) at a ratio of 68% by mass of the above component a, 30% by mass of component b, and 2% by mass of component c.

[0087] Comparative 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 components b and c were not used.

[0088] Example 1 Hereinafter, it will be described with reference to FIG. 1. The pellets of the PP composition granulated in Preparation Example 1 were put into an extruder, melted, and then extruded into a sheet shape. At the same time, with respect to the extruded sheet-shaped thermoplastic resin composition (X) (hereinafter referred to as "sheet X"; 11 in FIG. 1), a glass fiber mat A (12 in FIG. 1) was sandwiched from both sides to obtain a laminate. Here, the glass fiber mat A used has a needle punching depth of 16.0 mm. Next, sheet X (13 in FIG. 1) was laminated on both surfaces of the laminate, and while applying a pressure of 0.3 MPa using a laminator, heating and pressurization were performed at 230 °C for 4 minutes, and then cooling and solidification were carried out to obtain a stampable sheet (thickness:

[0089] The layer structure and composition of Example 1 are shown in Table 1. Also, the results evaluated by the above method are shown in Table 2. In Table 2, the results of evaluation are shown with the surface on the sheet X side as the flame contact surface as the outermost layer.

[0089] Example 2 The following explanation will use Figure 2. In Preparation Example 1, pellets of the granulated PP composition were placed in an extruder, melted, and then extruded into a sheet. The extruded sheet-like thermoplastic resin composition (X) (sheet X, 21 in Figure 2) was then laminated between glass fiber mats B (22 in Figure 2) to obtain a laminate. Next, glass fiber mats B (22' in Figure 2) were laminated onto both surfaces of the laminate. Sheet X was further laminated onto both surfaces so that the outermost layer would be sheet X (21'' in Figure 2). Subsequently, a stampable sheet (thickness: 2.5 mm) was obtained by heating and pressurizing at 230°C for 4 minutes under a pressure of 0.3 MPa using a laminator, and then cooling and solidifying. In the stampable sheet, the thermoplastic resin composition components in sheet X were impregnated into the three glass fiber mats B, forming a layer in which the glass fiber mats and the resin composition were integrated. The layer structure and composition of Example 3 are shown in Table 1. The results of the evaluation using the above method are shown in Table 2.

[0090] Comparative Example 1 In Example 1, a stampable sheet was obtained in the same manner as in Example 1, except that glass fiber mat B was used instead of glass fiber mat A, and the pellets obtained in Comparative Preparation Example 1 were used (thickness: 2.5 mm). The layer structure and composition of Comparative Example 1 are shown in Table 1. The evaluation results are shown in Table 2.

[0091] [Table 1]

[0092] [Table 2]

[0093] As shown in Examples 1 and 2, the stampable sheet of the present invention exhibited excellent flame-retardant properties, with flames being blocked even after 15 minutes. Furthermore, the maximum temperature reached up to 120 seconds (2 minutes) was suppressed, demonstrating excellent heat insulation properties. In contrast, in Comparative Example 1, the flame penetrated to the back surface in about 140 seconds. Furthermore, the maximum temperature reached up to 120 seconds (2 minutes) was significantly higher than in Examples 1 and 2. [Industrial applicability]

[0094] The stampable sheet of the present invention has high flame-retardant and heat-insulating properties, making it useful as a material for various industrial parts requiring high safety, such as aircraft, ships, automobile parts, electrical and electronic equipment components, and building materials. In particular, it can be suitably used in various housings and enclosures of batteries, where metal has conventionally been used, contributing to automobile safety and is expected to improve energy efficiency through weight reduction and reduce CO2 emissions. [Explanation of symbols]

[0095] 10 Stampable Sheets 11 Sheet X (Thermoplastic Resin Sheet) 12 Fiberglass Mat A 13 Sheet X (Thermoplastic Resin Sheet) 20 Stampable Sheets 21 Sheet X (Thermoplastic Resin Sheet) 21' Sheet X (Thermoplastic Resin Sheet) 22 Fiberglass Mat B 22' Fiberglass Mat B

Claims

1. A stampable sheet comprising a thermoplastic resin composition (X) and inorganic fibers (Y), The thermoplastic resin composition (X) comprises a thermoplastic resin and a phosphorus-based flame retardant. The inorganic fiber (Y) is an inorganic fiber nonwoven fabric. The phosphorus-based flame retardant is an intomessent flame retardant. A stampable sheet that expands by more than 300% when heated at 1200°C for 5 minutes.

2. The stampable sheet according to claim 1, wherein the needle penetration depth of the inorganic fiber nonwoven fabric is 15 mm or more.

3. The stampable sheet according to claim 1, wherein the thermoplastic resin constituting the thermoplastic resin composition (X) is a polyolefin resin.

4. The stampable sheet according to claim 1, wherein the thermoplastic resin composition (X) further comprises a dispersant.

5. The stampable sheet according to claim 4, wherein the dispersant is a copolymer of an α-olefin and an unsaturated carboxylic acid.

6. The stampable sheet according to claim 4, wherein the content of the dispersant relative to 100 parts by mass of the phosphorus-based flame retardant is greater than 0 and less than or equal to 25 parts by mass.

7. The stampable sheet according to claim 1, wherein the inorganic fiber (Y) is at least one selected from glass fiber, ceramic fiber, metal fiber, and metal oxide fiber.

8. The stampable sheet according to claim 1, wherein the content of the phosphorus-based flame retardant is 1 to 30% by mass with respect to the total weight.

9. A molded body obtained by stamping a stampable sheet according to any one of claims 1 to 8.

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