Laminate, housing for accommodating battery, battery pack, and movable body

Abstract

The present invention provides a laminate comprising a flame retardant layer containing a resin and a flame retardant, reinforcing fibers, and a matrix resin. The thermal conductivity on the surface of a heat-conductive layer is 0.2-10 W / m∙K, or the reinforcing fibers are arranged in one direction or a plurality of directions.

Description

Laminate, housing for accommodating battery, battery pack, and mobile body

[0001] The present invention relates to a laminate, a housing for accommodating a battery, a battery pack, and a mobile object.

[0002] Traditionally, metals such as iron have been used for barriers that require fire resistance and heat resistance. However, in recent years, development of barriers made of resin has also been progressing for the purpose of weight reduction. For example, a housing for housing a battery and installing it in an electric vehicle is required to have fire resistance and heat resistance that can withstand thermal runaway of the battery. Furthermore, by making the housing out of lightweight resin, it is expected that the fuel efficiency of the electric vehicle can also be improved.

[0003] As a resin material with excellent fire resistance, Patent Document 1 describes a laminate having a core member containing a foam and an outer layer reinforced with fibers embedded in polyvinylidene fluoride (PVDF). Patent Document 2 describes a laminate having a flame-retardant foam layer with a flammability level of V-2 to V-0 measured based on the UL94 vertical flame test, and a non-combustible layer containing a fiber-reinforced resin and having an oxygen index of 25 or higher as determined in accordance with JIS K7201-2. Patent Document 2 also describes that when a gas burner was applied to the non-combustible layer containing the fiber-reinforced resin, the laminate was resistant to temperature rise, deformation, and ignition.

[0004] JP 2016-519010 A International Publication No. 2022 / 209723

[0005] As described in Patent Documents 1 and 2, resin materials with excellent fire resistance have been investigated. However, applications using such materials often require not only fire resistance but also high-temperature impact resistance. For example, a housing for a battery is required to have heat resistance sufficient to withstand thermal runaway of the battery, as well as to be resistant to deformation and damage caused by high-temperature ejection material emitted from the battery during thermal runaway. However, laminates having a foam layer as described in Patent Documents 1 and 2 have problems such as being easily deformed by heat and being easily damaged due to low strength.

[0006] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a laminate that is highly heat resistant and is resistant to deformation at high temperatures and damage due to impact, a housing that houses a battery including the laminate, a battery pack including the housing, and a mobile object that includes the battery.

[0007] One aspect of the present invention for solving the above problems relates to laminates according to the following [1] to

[11] . [1] A laminate comprising a flame-retardant layer containing a resin composition including a flame retardant, and a thermally conductive layer containing reinforcing fibers and a matrix resin, wherein the thermally conductive layer has a thermal conductivity of 0.2 W / m·K or more and 10 W / m·K or less at the surface, or is a layer in which the reinforcing fibers are oriented in one direction or multiple directions. [2] The laminate according to [1], wherein the thermally conductive layer contains carbon fibers as the reinforcing fibers. [3] The laminate according to [1] or [2], wherein the thermally conductive layer is a layer in which the reinforcing fibers are oriented in one direction or multiple directions. [4] The laminate according to [3], wherein the thermally conductive layer is a layer containing the reinforcing fibers oriented in multiple directions that are perpendicular to each other. [5] The laminate according to [3] or [4], wherein the layer containing reinforcing fibers is formed from a sheet-like molding containing the reinforcing fibers oriented in one direction and the matrix resin impregnated into the reinforcing fibers. [6] The laminate according to any one of [1] to [5], wherein the flame-retardant layer contains reinforcing fibers. [7] The laminate according to [6], wherein the flame-retardant layer contains glass fibers as the reinforcing fibers. [8] The laminate according to [6] or [7], wherein the flame-retardant layer is a layer in which the reinforcing fibers are randomly arranged. [9] The laminate according to any one of [1] to [8], wherein the thermally conductive layer contains polyolefin as the matrix resin, and the flame-retardant layer contains polyolefin.

[10] The laminate according to any one of [1] to [9], wherein the thermally conductive layer contains polypropylene as the matrix resin, and the flame-retardant layer contains polypropylene.

[11] The laminate according to any one of [1] to

[10] , which is a heat-resistant member and has the thermally conductive layer disposed on the side opposite to the side where heat is generated with respect to the flame-retardant layer.

[0008] Another aspect of the present invention for solving the above problems relates to a housing for housing a battery according to the following items

[12] and

[13] .

[12] A housing for housing a battery, which includes the laminate according to any one of items [1] to

[11] in at least a part of a wall surface.

[13] A housing for housing the battery according to item

[12] , which includes the laminate in a lid material.

[0009] Another aspect of the present invention for solving the above problem relates to a battery pack according to the following item

[14] :

[14] A battery pack comprising: a housing for housing the battery according to item

[12] or

[13] ; and the battery housed in the housing.

[0010] Another aspect of the present invention for solving the above problem relates to a mobile body as set forth in the following

[15] :

[15] A mobile body having the battery pack as set forth in

[14] .

[0011] According to the present invention, there are provided a laminate that is highly heat resistant and is resistant to deformation at high temperatures and damage due to impact, a housing that houses a battery including the laminate, a battery pack including the housing, and a mobile device that includes the battery.

[0012] Figures 1A and 1B are cross-sectional views showing a schematic configuration of a laminate according to a first embodiment of the present invention. Figures 2A and 2B are cross-sectional views in a direction perpendicular to the stacking direction, showing an exemplary configuration of a thermally conductive layer. Figure 3 is a cross-sectional view in a direction perpendicular to the stacking direction, showing an exemplary configuration of a flame-retardant layer. Figure 4A is a perspective view showing a schematic configuration of a battery pack in which batteries are housed in a housing including a laminate. Figure 4B is an exploded view of the battery pack shown in Figure 4A.

[0013] 1A and 1B are cross-sectional views showing a schematic configuration of a laminate according to a first embodiment of the present invention. The laminate 100 includes a flame-retardant layer 110 and a thermally conductive layer 120. The flame-retardant layer 110 is a layer containing a resin composition including a flame retardant. The thermally conductive layer 120 is a layer containing reinforcing fibers and a matrix resin.

[0014] The flame-retardant layer 110, which contains a flame retardant, enhances the heat resistance and flame resistance of the laminate 100. Furthermore, the thermally conductive layer 120, which has high thermal conductivity, dissipates heat accumulated in the flame-retardant layer 110 laterally (in a direction perpendicular to the stacking direction) and toward the surface of the thermally conductive layer 120. Due to the effects of these layers, the laminate 100 has high heat resistance and flame resistance, and is less susceptible to damage or deformation due to heat. Furthermore, because the thermally conductive layer 120 contains reinforcing fibers, it is strong and less susceptible to deformation. Therefore, the laminate 100 is less susceptible to damage or deformation even when subjected to impact at high temperatures. The flame-retardant layer may or may not contain reinforcing fibers.

[0015] The thermal conductivity of the surface of the thermally conductive layer 120 is preferably 0.2 W / m·K or more and 10 W / m·K or less, and more preferably 1.0 W / m·K or more and 7.0 W / m·K or less. The thermal conductivity of the surface of the thermally conductive layer 120 can be a value measured by a laser flash method. When the thermally conductive layer 120 is located inside another layer, the other layer on the surface side can be removed to expose the thermally conductive layer 120, and the thermal conductivity of the surface can be measured. The thermal conductivity of the thermally conductive layer 120 can be adjusted by changing the type or content of the reinforcing fibers 122 (described below) or the type or content of the matrix resin 124.

[0016] The number of flame-retardant layers 110 and thermally conductive layers 120 is not particularly limited. The laminate 100 may have one flame-retardant layer 110 and one thermally conductive layer 120, one of either layer and multiple layers of the other, or multiple layers of both. For example, the laminate 100 shown in FIG. 1A is a two-layer laminate having one flame-retardant layer 110 and one thermally conductive layer 120. The laminate 100 shown in FIG. 1B is a three-layer laminate having one flame-retardant layer 110 and two thermally conductive layers 120 arranged on either side of the flame-retardant layer 110. However, the number of each layer is not limited to these, and multiple flame-retardant layers 110 and multiple thermally conductive layers 120 may be stacked. The two-layer laminate 100 shown in FIG. 1A can reduce the overall thickness, increasing the design flexibility of components using the laminate 100. In the laminate 100 shown in FIG. 1B , in which the thermally conductive layers 120 are disposed on both sides of the flame-retardant layer 110, the thermally conductive layers 120 on both sides are relatively resistant to deformation, thereby suppressing warpage of the flame-retardant layer 110, improving the moldability of the laminate 100 and making it easier to give the laminate 100 a desired shape.

[0017] The laminate 100 may also have other layers in addition to these. The other layers may be disposed between the flame-retardant layer 110 and the thermally conductive layer 120, between two flame-retardant layers 110, between two thermally conductive layers 120, or as the outermost layer of the laminate 100 as a protective layer or the like.

[0018] 2A and 2B are cross-sectional views taken in a direction perpendicular to the stacking direction, showing an exemplary configuration of the thermally conductive layer 120. FIG.

[0019] As shown in Figures 2A and 2B, the thermally conductive layer 120 preferably includes reinforcing fibers 122 oriented in one or more directions and a matrix resin 124 impregnated into the reinforcing fibers 122. The aligned reinforcing fibers 122 serve as a heat conduction path, further enhancing the thermal conductivity of the thermally conductive layer 120. Also, as shown in Figures 2A and 2B, the thermally conductive layer 120 preferably includes multiple orientation layers 120a and 120b in which the reinforcing fibers 122 are oriented at different angles. The multiple orientation layers 120a and 120b further enhance the strength of the thermally conductive layer 120, making the laminate 100 less susceptible to breakage or deformation when subjected to an impact at high temperatures.

[0020] The configuration of the thermally conductive layer 120 is not limited to this. For example, the thermally conductive layer 120 may include reinforcing fibers 122, which are randomly arranged short fibers. From the viewpoint of facilitating heat dissipation from the surface of the thermally conductive layer 120 and further improving the heat resistance, flame resistance, and impact resistance at high temperatures of the laminate 100, it is preferable that the laminate 100 have a thermally conductive layer 120 that does not have any other flame-retardant layers 110 on the outer side thereof.

[0021] When the thermally conductive layer 120 includes reinforcing fibers oriented in one direction and a matrix resin impregnated into the reinforcing fibers, the orientation direction of the reinforcing fibers is not particularly limited. Furthermore, when the thermally conductive layer 120 includes reinforcing fibers oriented in multiple directions and a matrix resin impregnated into the reinforcing fibers, the angle at which the reinforcing fibers in one orientation layer of the thermally conductive layer 120 are oriented relative to the angle (assumed to be 0°) at which the reinforcing fibers in the other orientation layers are oriented can be ±90°, ±45°, or any other angle. From the perspective of further improving the heat resistance, flame resistance, and impact resistance at high temperatures of the laminate 100, it is preferable that the thermally conductive layer 120 have a layer in which the reinforcing fibers are oriented at ±90° relative to 0° (i.e., the thermally conductive layer 120 includes reinforcing fibers oriented in multiple directions perpendicular to each other).

[0022] When the thermally conductive layer 120 includes reinforcing fibers oriented in multiple different directions, the reinforcing fibers oriented at 0° and the reinforcing fibers oriented in other directions (e.g., 90°) may form a woven fabric or may be included in different orientation layers. From the viewpoint of further improving the impact resistance of the laminate 100 at high temperatures, it is preferable that the reinforcing fibers oriented in multiple directions be included in different orientation layers. On the other hand, forming a woven fabric makes it difficult for the reinforcing fibers to shift during the manufacturing of the laminate 100, making it easier to mold.

[0023] 1B , when the laminate 100 has thermally conductive layers 120 on both sides of the flame-retardant layer 110, the types of matrix resin, the types of reinforcing fibers, the lengths of the fibers, the number and arrangement of each orientation layer when the fibers are long, the orientation direction of each orientation layer, and the stacking order of the orientation layers may be the same or different. From the viewpoint of making it easier to suppress warpage of the flame-retardant layer 110 by the thermally conductive layers 120, it is preferable that the thermally conductive layers 120 on both sides have the same type of matrix resin and the same type and arrangement of reinforcing fibers, and it is more preferable that the orientation layers have the same orientation angle of the reinforcing fibers arranged symmetrically across the flame-retardant layer 110.

[0024] The thermally conductive layer 120 preferably has a thermal conductivity of 0.2 W / m·K or more and 10 W / m·K or less at the surface, or is a layer in which the reinforcing fibers 122 are oriented in one direction or multiple directions. Such a configuration makes it easier to dissipate heat from the surface of the thermally conductive layer 120, thereby further improving the heat resistance, flame resistance, and impact resistance at high temperatures of the laminate 100.

[0025] The thickness of the flame-retardant layer 110 (when the laminate 100 has multiple flame-retardant layers 110, the thickness of each flame-retardant layer 110) can be increased to improve the heat resistance, flame resistance, and strength of the laminate 100. On the other hand, the thickness of the flame-retardant layer 110 can be reduced to reduce the living space and increase the cruising range due to increased battery capacity. From the viewpoint of balancing these factors, the thickness of the flame-retardant layer 110 is preferably 1000 μm or more and 4000 μm or less, and more preferably 2000 μm or more and 3000 μm or less. By making the thickness of the flame-retardant layer 110 1000 μm or more, the heat resistance and fire resistance of the laminate 100 can be further improved. By making the thickness of the flame-retardant layer 110 4000 μm or less, the overall thickness of the laminate 100 can be reduced, thereby increasing the degree of freedom in designing components using the laminate 100. When the laminate 100 has a plurality of flame-retardant layers 110, the thicknesses of these flame-retardant layers 110 may be the same or different.

[0026] The overall thickness of the thermally conductive layer 120 (when the laminate 100 has multiple thermally conductive layers 120, the combined thickness of the multiple thermally conductive layers 120) is preferably 100 μm or more and 3000 μm or less, more preferably 300 μm or more and 2000 μm or less, and even more preferably 500 μm or more and 1000 μm or less. Furthermore, the thickness of each thermally conductive layer 120 is preferably 50 μm or more and 2000 μm or less, more preferably 150 μm or more and 1800 μm or less, and even more preferably 250 μm or more and 500 μm or less. By making the thickness of the thermally conductive layer 120 150 μm or more, the laminate 100 can be made less susceptible to damage or deformation due to heat, or damage or deformation when subjected to impact at high temperatures. By making the thickness of the thermally conductive layer 120 2000 μm or less, the overall thickness of the laminate 100 can be reduced, thereby increasing the degree of freedom in designing components using the laminate 100. When the laminate 100 has a plurality of thermally conductive layers 120, the thicknesses of these thermally conductive layers 120 may be the same or different.

[0027] The ratio of the thickness of the flame-retardant layer 110 to the thickness of the thermally conductive layer 120 (when there are multiple layers, the ratio of their average thicknesses) (thickness of the flame-retardant layer 110) / (thickness of the thermally conductive layer 120) is preferably 2000 / 3000 or more and 4000 / 150 or less, and more preferably 2000 / 1800 or more and 2000 / 150 or less. The higher the thickness ratio of the flame-retardant layer 110, the more the heat resistance and fire resistance of the laminate 100 can be improved. The higher the thickness ratio of the thermally conductive layer 120, the more the laminate 100 can be made less susceptible to damage or deformation due to heat, or to damage or deformation when subjected to impact at high temperatures.

[0028] The thermally conductive layer 120 may be formed on the entire surface of the flame-retardant layer 110, or may be formed on only a portion of the surface of the flame-retardant layer 110; the flame-retardant layer 110 may be formed on the entire surface of the thermally conductive layer 120, or may be formed on only a portion of the surface of the thermally conductive layer 120.

[0029] 1-1. Flame-Retardant Layer 110 The flame-retardant layer is a layer containing a resin composition containing a flame retardant.

[0030] 1-1-1. Flame Retardant The type of flame retardant contained in the flame retardant layer 110 is not particularly limited.

[0031] Examples of flame retardants include organic halogen flame retardants, combinations of organic halogen flame retardants with one or more selected from the group consisting of antimony oxide, zinc borate, zinc stannate, and iron oxide, organic phosphorus flame retardants, combinations of organic phosphorus flame retardants with silicone compounds, combinations of inorganic phosphorus such as red phosphorus, organopolysiloxanes, and organic metal compounds, hindered amine flame retardants, inorganic flame retardants such as magnesium hydroxide, alumina, calcium borate, and low-melting-point glass, etc. These may be used alone or in combination of two or more.

[0032] Among these, organophosphorus flame retardants form a heat insulating layer during combustion, and therefore are less susceptible to combustion promotion due to capillary action of fibers that occurs during combustion than organohalogen flame retardants, and therefore organophosphorus flame retardants are preferred from the viewpoint of further improving the heat resistance and combustion resistance of the laminate 100.

[0033] Examples of the organophosphorus flame retardant include phosphate compounds, phosphine compounds, phosphinate compounds, phosphine oxide compounds, and phosphazene compounds.

[0034] Examples of the phosphate compound include phosphoric acid esters such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylyl phosphate, cresyl diphenyl phosphate, xylyl diphenyl phosphate, tolyldixylyl phosphate, tris(norylphenyl)phosphate, and (2-ethylhexyl)diphenyl phosphate; hydroxyl groups such as resorcinol diphenyl phosphate and hydroquinone diphenyl phosphate; and condensed phosphate ester compounds such as phosphate-containing esters, resorcinol bis(diphenyl phosphate), hydroquinone bis(diphenyl phosphate), bisphenol-A bis(diphenyl phosphate), bisphenol-S bis(diphenyl phosphate), resorcinol bis(dixylyl phosphate), hydroquinone bis(dixylyl phosphate), bisphenol-A bis(ditolyl phosphate), bisphenol-A bis(dixylyl phosphate), and bisphenol-S bis(dixylyl phosphate).

[0035] Examples of the phosphine compound include trilaurylphosphine, triphenylphosphine, tritolylphosphine, and the like.

[0036] The phosphinate compound is a compound represented by the following general formula (I).

[0037]

[0038] In formula (1), R １ and R ２ are each independently a linear or branched alkyl group or an aryl group having from 1 to 6 carbon atoms. M is at least one metal atom selected from the group consisting of Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, and K. m is an integer of from 1 to 4.

[0039] Specific examples of the phosphinate compound include aluminum diethylphosphinate, magnesium diethylphosphinate, and the like.

[0040] Examples of the phosphine oxide compound include triphenylphosphine oxide and tritolylphosphine oxide.

[0041] Examples of the phosphazene compound include hexaphenoxycyclotriphosphazene, monophenoxypentakis(4-cyanophenoxy)cyclotriphosphazene, diphenoxytetrakis(4-cyanophenoxy)cyclotriphosphazene, triphenoxytris(4-cyanophenoxy)cyclotriphosphazene, tetraphenoxybis(4-cyanophenoxy)cyclotriphosphazene, pentaphenoxy(4-cyanophenoxy)cyclotriphosphazene, monophenoxypentakis(4-methoxyphenoxy)cyclotriphosphazene, C) Cyclotriphosphazene, diphenoxytetrakis(4-methoxyphenoxy)cyclotriphosphazene, triphenoxytris(4-methoxyphenoxy)cyclotriphosphazene, tetraphenoxybis(4-methoxyphenoxy)cyclotriphosphazene, pentaphenoxy(4-methoxyphenoxy)cyclotriphosphazene, monophenoxypentakis(4-methylphenoxy)cyclotriphosphazene, diphenoxytetrakis(4-methylphenoxy)cyclotriphosphazene, triphenoxy Triphenoxytris(4-methylphenoxy)cyclotriphosphazene, tetraphenoxybis(4-methylphenoxy)cyclotriphosphazene, pentaphenoxy(4-methylphenoxy)cyclotriphosphazene, triphenoxytris(4-ethylphenoxy)cyclotriphosphazene, triphenoxytris(4-propylphenoxy)cyclotriphosphazene, monophenoxypentakis(4-cyanophenoxy)cyclotriphosphazene, diphenoxytetrakis(4-hydroxyphenoxy)cyclotriphosphazene triphosphazene, triphenoxytris(4-hydroxyphenoxy)cyclotriphosphazene, tetraphenoxybis(4-hydroxyphenoxy)cyclotriphosphazene, pentaphenoxy(4-hydroxyphenoxy)cyclotriphosphazene, triphenoxytris(4-phenylphenoxy)cyclotriphosphazene, triphenoxytris(4-methacrylphenoxy)cyclotriphosphazene, triphenoxytris(4-acrylphenoxy)cyclotriphosphazene, and the like.

[0042] The content of the flame retardant relative to the total mass of each flame-retardant layer 110 is preferably 15% by mass or more and 45% by mass or less, more preferably 20% by mass or more and 40% by mass or less, and even more preferably 25% by mass or more and 30% by mass or less. The higher the content of the flame retardant, the higher the heat resistance and flame resistance of the flame-retardant layer 110 and the laminate 100. The lower the content of the flame retardant, the higher the strength and moldability of the flame-retardant layer 110 and the laminate 100.

[0043] The flame-retardant layer 110 preferably has a larger content of flame retardant by mass than the content of flame retardant in the thermally conductive layer 120. The flame-retardant layer 110, which has a higher content of flame retardant and improved heat resistance and fire resistance, can more efficiently suppress the spread of fire and heat-induced deformation of the laminate.

[0044] The flame-retardant layer 110 may contain a flame-retardant auxiliary in addition to the flame retardant. Examples of the flame-retardant auxiliary include metal oxides and metal hydroxides. Among these, zinc borate, boehmite, zinc stannate, iron oxide, and tin oxide are preferred, and zinc borate is more preferred.

[0045] The content of the flame retardant aid is preferably 0.1 mass% or more and 5.0 mass% or less, more preferably 0.5 mass% or more and 5.0 mass% or less, and even more preferably 1.0 mass% or more and 3.0 mass% or less, relative to the total mass of each flame retardant layer 110.

[0046] 1-1-2. Resin 114 The type of resin 114 contained in the flame-retardant layer 110 is not particularly limited. The resin 114 may be a thermoplastic resin or a thermosetting resin. These thermoplastic resins and thermosetting resins may be derived from fossil fuels, biomass raw materials, or a mixture thereof.

[0047] Examples of the thermoplastic resin include polyolefin resins such as polyethylene, polypropylene, polybutene, and poly4-methyl-1-pentene, polyamide resins, polyester resins, polystyrene resins, thermoplastic polyimide resins, polyamideimide resins, polycarbonate resins, polyphenylene ether resins, polyphenylene sulfide resins, polyacetal resins, acrylic resins, polyetherimide resins, polysulfone resins, polyether ketone resins, polyether ether ketone resins, polyarylate resins, polyether nitrile resins, vinyl chloride resins, ABS resins, and fluororesins.

[0048] Examples of the thermosetting resin include epoxy resin, phenol resin, melamine resin, urea resin, diallyl phthalate resin, silicone resin, urethane resin, furan resin, ketone resin, xylene resin, thermosetting polyimide resin, unsaturated polyester resin, and diallyl terephthalate resin.

[0049] Among these, thermoplastic resins are preferred from the viewpoint of improving recyclability and productivity. Among the thermoplastic resins, polyamide resins and polyolefin resins are preferred from the viewpoint of improving moldability, and polyolefin resins are more preferred, with polypropylene being even more preferred, from the viewpoint of improving water resistance and light weight.

[0050] The content of resin 114 relative to the total mass of each flame-retardant layer 110 is preferably 20% by mass or more and 80% by mass or less, more preferably 30% by mass or more and 60% by mass or less, and even more preferably 35% by mass or more and 52% by mass or less. The higher the content of resin 114, the more easily the flame-retardant layer 110 can be molded, making it easier to impart a desired shape to the laminate 100. The lower the content of resin 114, the more effectively the strength, heat resistance, and flame resistance of the flame-retardant layer 110 and the laminate 100 can be improved.

[0051] 1-1-3. Reinforcement Fiber 112 The flame-retardant layer 110 preferably contains reinforcing fiber.

[0052] The flame-retardant layer 110 containing reinforcing fibers has high strength and is resistant to deformation. Therefore, in addition to the heat resistance and fire resistance provided by the flame retardant, the flame-retardant layer 110 imparts high strength to the laminate 100, making the laminate 100 less susceptible to breakage or deformation when subjected to impact at high temperatures. For example, a heat-resistant resin layer can be formed using a resin foam. However, foams cannot increase strength and are prone to breakage or deformation when subjected to impact at high temperatures. Furthermore, foams require a large thickness to increase heat resistance. In contrast, in this embodiment, the flame-retardant layer 110 containing reinforcing fibers and a flame retardant can increase the heat resistance and fire resistance of the laminate while reducing its thickness, and further make the laminate less susceptible to breakage or deformation when subjected to impact at high temperatures.

[0053] Furthermore, when the flame-retardant layer 110 contains reinforcing fibers, the reinforcing fibers act as a path for dissipating heat within the flame-retardant layer 110, making it easier for heat to be dissipated from the laminate 100, thereby further improving the heat resistance, flame resistance, and impact resistance at high temperatures of the laminate 100.

[0054] FIG. 3 is a cross-sectional view taken perpendicular to the lamination direction, showing an exemplary configuration of a flame-retardant layer 110 including reinforcing fibers 112.

[0055] 3, the flame-retardant layer 110 including the reinforcing fibers 112 preferably includes the reinforcing fibers 112, which are randomly arranged short fibers, and a matrix resin 114. The short reinforcing fibers 112 improve the moldability of the flame-retardant layer 110 (e.g., moldability by injection molding), making it easier to impart a desired shape to the laminate 100. Furthermore, the flame-retardant layer 110 in which the short reinforcing fibers 112 are randomly arranged tends to increase strength against impacts from multiple directions, particularly strength against impacts in the stacking direction.

[0056] However, the configuration of the flame-retardant layer 110 is not limited to this. For example, the flame-retardant layer 110 may include reinforcing fibers 112 that are oriented in one direction or in multiple directions.

[0057] When the flame-retardant layer 110 includes reinforcing fibers oriented in one direction and a matrix resin impregnated into the reinforcing fibers, the orientation direction of the reinforcing fibers is not particularly limited. Furthermore, when the flame-retardant layer 110 includes reinforcing fibers oriented in multiple directions and a matrix resin impregnated into the reinforcing fibers, the angle at which the reinforcing fibers in one orientation layer of the flame-retardant layer 110 are oriented relative to the angle (defined as 0°) at which the reinforcing fibers in the other orientation layers are oriented can be ±90°, ±45°, or any other angle.

[0058] The type of reinforcing fibers 112 contained in the flame-retardant layer 110 is not particularly limited. For example, the reinforcing fibers 112 may be carbon fibers, glass fibers, aramid fibers, alumina fibers, silicon carbide fibers, boron fibers, metal fibers, etc. Of these, from the viewpoint of increasing the strength of the flame-retardant layer 110 and the laminate 100, the reinforcing fibers 112 are preferably carbon fibers or glass fibers, and from the viewpoint of further increasing the heat resistance and combustion resistance of the flame-retardant layer 110 and the laminate 100, glass fibers are more preferable.

[0059] The reinforcing fibers 112 may be short fibers having an average fiber length of less than 1.0 mm, or long fibers having an average fiber length of 1.0 mm or more.

[0060] The average fiber length of the reinforcing fibers 112 is preferably 0.01 mm or more and 100 mm or less, more preferably 0.1 mm or more and 50 mm or less, and even more preferably 1 mm or more and 30 mm or less. When the average fiber length is within the above range, it is easy to increase the mechanical strength of the laminate 100. Note that, when it is desired to increase the strength of the laminate 100 (particularly the strength against impact in the stacking direction), the average fiber length of the reinforcing fibers 112 is preferably less than 1.0 mm, more preferably 100 μm or more and 800 μm or less, and even more preferably 200 μm or more and 500 μm or less.

[0061] The average fiber diameter of the reinforcing fibers is preferably 1 μm or more and 30 μm or less, and more preferably 5 μm or more and 20 μm or less. When the average fiber diameter is within the above range, the mechanical strength (particularly impact resistance and rigidity), heat resistance, and flame resistance of the laminate 100 are easily improved.

[0062] The average fiber length and average fiber diameter of the reinforcing fibers 112 can be determined, for example, by measuring the lengths and diameters of 100 reinforcing fibers 112 randomly selected from a photograph of the reinforcing fibers 112 taken with an optical microscope, and then taking the arithmetic average.

[0063] The reinforcing fibers 112 may be bundled with a sizing agent, which may be any of an acrylic sizing agent, a urethane sizing agent, an acid copolymer sizing agent, or the like.

[0064] The mass ratio (loss on ignition) of the sizing agent to the reinforcing fibers 112 is preferably 0.1% by mass or more and 1.5% by mass or less. When the loss on ignition is 0.1% by mass or more, the interface between the reinforcing fibers 112 and the matrix resin 114 is stabilized, and the heat resistance and flame resistance of the laminate 100 are likely to be improved. When the loss on ignition is 1.5% by mass or less, the heat resistance and flame resistance of the laminate 100 are less likely to be reduced by the sizing agent. The mass ratio (loss on ignition) of the sizing agent is a value measured on fibers obtained by applying the sizing agent to the reinforcing fibers with an applicator or the like and drying the fibers to completely volatilize the volatile substances, in accordance with JIS R 3420:2006 7.3.2.

[0065] The content of the reinforcing fibers 112 relative to the total mass of each flame-retardant layer 110 is preferably 10% by mass or more and 50% by mass or less, more preferably 20% by mass or more and 40% by mass or less, and even more preferably 25% by mass or more and 35% by mass or less. The greater the content of the reinforcing fibers 112, the greater the strength of the flame-retardant layer 110 and the laminate 100, making the laminate 100 less susceptible to breakage or deformation. The smaller the content of the reinforcing fibers 112, the greater the heat resistance, flame resistance, and moldability of the flame-retardant layer 110 and the laminate 100.

[0066] 1-1-4. Other Components The flame-retardant layer 110 may contain other known components.

[0067] Examples of other components include nucleating agents, lubricants, colorants (pigments, dyes), corrosion resistance improvers, anti-drip agents, ion scavengers, elastomers (rubbers), antistatic agents, anti-slip agents, antifungal agents, antibacterial agents, softeners, mold release agents, antioxidants (phenols, amines, sulfurs, phosphorus compounds, etc.), and light stabilizers (benzotriazoles, triazines, benzophenones, benzoates, hindered amines, oxanilides, etc.).

[0068] 1-2. Thermal Conduction Layer 120 1-2-1. Reinforcement Fibers 122 The type of reinforcing fibers 122 contained in the thermal conduction layer 120 is not particularly limited. For example, the reinforcing fibers 122 may be carbon fibers, glass fibers, aramid fibers, alumina fibers, silicon carbide fibers, boron fibers, metal fibers, or the like. Of these, from the viewpoint of increasing the strength of the thermal conduction layer 120 and the laminate 100, the reinforcing fibers 122 are preferably carbon fibers or glass fibers. However, from the viewpoint of further increasing the thermal conductivity of the thermal conduction layer 120, facilitating heat dissipation from the surface of the thermal conduction layer 120, and further improving the heat resistance, combustion resistance, and impact resistance at high temperatures of the laminate 100, carbon fibers are more preferable.

[0069] The reinforcing fibers 122 may be short fibers having an average fiber length of less than 1.0 mm, or long fibers having an average fiber length of 1.0 mm or more.

[0070] The average fiber length of the reinforcing fibers 122 is preferably 0.01 mm or more and 100 mm or less, more preferably 0.1 mm or more and 50 mm or less, and even more preferably 1 mm or more and 30 mm or less. When the average fiber length is within the above range, the mechanical strength of the laminate 100 is easily increased. When it is desired to increase the thermal conductivity of the thermally conductive layer 120, the average fiber length of the reinforcing fibers 112 is preferably 1.0 mm or more, more preferably 15 mm or more, even more preferably 20 mm or more, even more preferably 100 mm or more, and particularly preferably 500 mm or more. The maximum upper limit of the length of the reinforcing fibers 122 is, for example, 50 m.

[0071] The average fiber diameter of the reinforcing fibers 122 is preferably 1 μm or more and 30 μm or less, and more preferably 5 μm or more and 20 μm or less. When the average fiber diameter is within the above range, the mechanical strength (particularly impact resistance and rigidity), heat resistance, and flame resistance of the laminate 100 are easily improved, and the appearance of the laminate 100 is improved.

[0072] The average fiber length and average fiber diameter of the reinforcing fibers 122 can be determined, for example, by measuring the lengths and diameters of 100 reinforcing fibers 122 randomly selected from a photograph of the reinforcing fibers 122 taken with an optical microscope, and then taking the arithmetic average.

[0073] The reinforcing fibers 122 may also be subjected to a sizing treatment using a sizing agent.

[0074] The sizing agent is not particularly limited, but is preferably a modified polyolefin, more preferably a modified polyolefin containing a metal carboxylate. The modified polyolefin is, for example, an unmodified polyolefin in which a carboxylic acid group, a carboxylic anhydride group, or a carboxylic ester group is grafted onto the polymer chain of the unmodified polyolefin, and a salt is formed between the functional group and a metal cation.

[0075] The unmodified polyolefin is preferably an ethylene polymer containing 50 mol% or more of structural units derived from ethylene, or a propylene polymer containing 50 mol% or more of structural units derived from propylene. Examples of the ethylene polymer include ethylene homopolymers and copolymers of ethylene and an α-olefin having from 3 to 10 carbon atoms. Examples of the propylene polymer include propylene homopolymers and copolymers of propylene and ethylene or an α-olefin having from 4 to 10 carbon atoms. The unmodified polyolefin is preferably homopolypropylene, homopolyethylene, ethylene-propylene copolymer, propylene-1-butene copolymer, or ethylene-propylene-1-butene copolymer. The α-olefins constituting these unmodified polyolefins and modified polyolefins may be derived from fossil fuels, biomass materials, or mixtures thereof.

[0076] Furthermore, when the reinforcing fibers 122 are long fibers, they may be gathered into fiber bundles and then opened. In this case, the number of single fibers per converged carbon fiber bundle is preferably 100 to 100,000, and more preferably 1,000 to 50,000.

[0077] The content of the reinforcing fibers 122 relative to the total mass of each thermally conductive layer 120 is preferably 50% by mass or more and 90% by mass or less, more preferably 60% by mass or more and 80% by mass or less, and even more preferably 65% ​​by mass or more and 75% by mass or less. The greater the content of the reinforcing fibers 122, the greater the strength of the thermally conductive layer 120 and the laminate 100, making the laminate 100 less susceptible to breakage or deformation. Furthermore, when the reinforcing fibers are highly thermally conductive fibers such as carbon fibers, the greater the content of the reinforcing fibers 122, the greater the thermal conductivity of the thermally conductive layer 120. The smaller the content of the reinforcing fibers 122, the greater the moldability of the thermally conductive layer 120 and the laminate 100.

[0078] The thermally conductive layer 120 preferably has a larger reinforcing fiber content by mass than the reinforcing fiber content of the flame-retardant layer 110. The thermally conductive layer 120 has a higher reinforcing fiber content, which increases its strength and makes it less susceptible to deformation, thereby more efficiently suppressing thermal deformation of the flame-retardant layer 110.

[0079] 1-2-2. Matrix Resin 124 The type of matrix resin 124 contained in the thermally conductive layer 120 is not particularly limited. The matrix resin 124 may be a thermoplastic resin or a thermosetting resin. These thermoplastic resins and thermosetting resins may be derived from fossil fuels, biomass materials, or a mixture thereof.

[0080] Examples of the thermoplastic resin include polyolefin resins such as polyethylene, polypropylene, polybutene, and poly4-methyl-1-pentene, polyamide resins, polyester resins, polystyrene resins, thermoplastic polyimide resins, polyamideimide resins, polycarbonate resins, polyphenylene ether resins, polyphenylene sulfide resins, polyacetal resins, acrylic resins, polyetherimide resins, polysulfone resins, polyether ketone resins, polyether ether ketone resins, polyarylate resins, polyether nitrile resins, vinyl chloride resins, ABS resins, and fluororesins.

[0081] Examples of the thermosetting resin include epoxy resin, phenol resin, melamine resin, urea resin, diallyl phthalate resin, silicone resin, urethane resin, furan resin, ketone resin, xylene resin, thermosetting polyimide resin, unsaturated polyester resin, and diallyl terephthalate resin.

[0082] Among these, thermoplastic resins are preferred from the viewpoint of improving recyclability and productivity. Among the thermoplastic resins, polyamide resins and polyolefin resins are preferred from the viewpoint of improving moldability, and polyolefin resins are more preferred, with polypropylene being even more preferred, from the viewpoint of improving water resistance and light weight.

[0083] Furthermore, the matrix resin 124 contained in the thermally conductive layer 120 may be the same type of resin as the matrix resin 114 contained in the flame-retardant layer 110, or may be a different type of resin. From the viewpoint of further increasing the bonding strength between the flame-retardant layer 110 and the thermally conductive layer 120, it is preferable that these matrix resins be thermoplastic resins that are mutually compatible. "Compatible" means that these thermoplastic resins are combined in such a way that a single phase is formed when they are heated to a temperature higher than the melting points of all the resins, mixed, and then cooled to 25°C. From the same viewpoint, it is also preferable that these matrix resins be the same type of resin.

[0084] The content of the matrix resin 124 relative to the total mass of each thermally conductive layer 120 is preferably 10% by mass or more and 50% by mass or less, more preferably 20% by mass or more and 40% by mass or less, and even more preferably 25% by mass or more and 35% by mass or less. The higher the content of the matrix resin 124, the more easily the thermally conductive layer 120 can be molded, making it easier to impart a desired shape to the laminate 100. The lower the content of the matrix resin 124, the more effectively the strength, heat resistance, and flame resistance of the thermally conductive layer 120 and the laminate 100 can be improved.

[0085] 1-2-3. Other Components The thermally conductive layer 120 may contain other known components.

[0086] Examples of other components include nucleating agents, lubricants, colorants (pigments, dyes), corrosion resistance improvers, anti-drip agents, ion scavengers, elastomers (rubbers), antistatic agents, anti-slip agents, flame retardants, flame retardant aids, antifungal agents, antibacterial agents, flame retardants, softeners, mold release agents, antioxidants (phenols, amines, sulfurs, phosphorus compounds, etc.), and light stabilizers (benzotriazoles, triazines, benzophenones, benzoates, hindered amines, oxanilides, etc.).

[0087] The thermally conductive layer 120 may contain a flame retardant. Examples of the flame retardant contained in the thermally conductive layer 120 include the various compounds described as the flame retardants that may be contained in the flame-retardant layer 110. The flame retardant contained in the thermally conductive layer 120 may be the same compound as the flame retardant contained in the flame-retardant layer 110, or may be a different compound. Note that the amount of flame retardant contained in the thermally conductive layer 120 is preferably less than the amount of flame retardant contained in the flame-retardant layer 110.

[0088] The thermally conductive layer 120 may also contain metal materials (such as metal particles) for increasing thermal conductivity, and the thermal conductivity at the surface may be increased by these materials for increasing thermal conductivity.

[0089] 2. Method for Producing the Laminate The method for producing the laminate 100 is not particularly limited.

[0090] For example, the flame-retardant layer 110 and the thermally conductive layer 120 may be prepared and bonded together with an adhesive or a double-sided adhesive sheet.

[0091] Furthermore, when the matrix resin 114 contained in the flame-retardant layer 110 and the matrix resin 124 contained in the thermally conductive layer 120 are both thermoplastic resins, the laminate 100 may be manufactured by joining these layers using a method such as heat press molding or fusion bonding by laser irradiation.

[0092] Alternatively, the laminate 100 may be manufactured by insert molding, in which the material of the other thermally conductive layer 120 or flame-retardant layer 110 is melted and injected into a mold in which a previously prepared flame-retardant layer 110 or thermally conductive layer 120 is placed. Alternatively, the laminate 100 may be manufactured by a molding method suited to the type of resin, the shape of the laminate 100, or the like, such as co-extrusion molding, compression molding, transfer molding, vacuum molding, or compressed air molding.

[0093] The flame-retardant layer 110 or the thermally conductive layer 120 may be prepared in advance by a known method such as injection molding, extrusion molding, or press molding. For example, the flame-retardant layer 110 or the thermally conductive layer 120, which includes reinforcing fibers oriented in one direction or multiple directions and a matrix resin impregnated into the reinforcing fibers, may be a sheet-shaped molded product (UD sheet) containing the reinforcing fibers oriented in one direction and the matrix resin impregnated into the reinforcing fibers, or may be a product obtained by stacking multiple UD sheets and fusing them together under heat and pressure. When fusing multiple UD sheets, the orientation direction of the reinforcing fibers can be changed for each stacked UD sheet, thereby obtaining a material for the flame-retardant layer 110 or the thermally conductive layer 120 containing reinforcing fibers oriented in multiple directions and a matrix resin impregnated into the reinforcing fibers.

[0094] 3. Uses of the Laminate The laminate 100 can be used as a fire-resistant and heat-resistant barrier in mobile objects such as automobiles, electric vehicles (including hybrid vehicles), trucks, buses, ships, trains, and airplanes, as well as in electrical appliances. Furthermore, because the laminate 100 is resistant to damage and deformation even when subjected to impact at high temperatures, it is preferably used as a barrier separating components that are subject to scattering due to explosions during combustion, such as internal combustion engines and fuel tanks, components that are subjected to high temperatures and high loads, such as oil field drilling equipment, and components that emit high-temperature ejecta due to thermal runaway, such as batteries, from other components. Furthermore, when the laminate 100 contains carbon fiber, it can also be used for electromagnetic wave shielding purposes.

[0095] When used as a heat-resistant member such as the partition wall, the laminate 100 preferably has at least one thermally conductive layer 120 disposed on the side opposite to the side where heat is generated relative to the flame-retardant layer 110. Such an arrangement makes it easier for the thermally conductive layer 120 to release heat absorbed by the flame-retardant layer 110 disposed on the heat-generating side, thereby efficiently exhibiting the heat resistance of the laminate 100 and suppressing thermal deformation of the flame-retardant layer 110. Furthermore, when the thermally conductive layer 120 has an orientation layer that is less likely to deform, the above arrangement more significantly suppresses thermal deformation of the flame-retardant layer 110.

[0096] Fig. 4A is a perspective view showing a schematic configuration of a battery pack in which batteries are housed in a case including the laminate 100. Fig. 4B is an exploded view of the battery pack shown in Fig. 4A.

[0097] 4A and 4B , battery pack 300 has a housing 310 and a battery 320 housed inside housing 310. Housing 310 has a housing member 312 that forms the side and bottom surfaces of housing 310, and a removable lid member 314 that forms the top surface of housing 310. Battery 320 is, for example, a secondary battery such as a lithium-ion secondary battery.

[0098] The battery 320 is housed inside the housing member 312 so that terminals 322, such as positive and negative electrodes, face the lid member 314. The lid member 314 is then attached to seal the battery 320. In this type of battery pack 300, if the battery 320 experiences thermal runaway, high-temperature ejection material is emitted from the terminal 322 toward the lid member 314. In this embodiment, the lid member 314 is formed from the laminate 100 described above. Therefore, the lid member 314 is less likely to be damaged or deformed by heat and ejection material when the battery 320 experiences thermal runaway. In this way, the safety of the battery pack 300 is further enhanced by the laminate 100.

[0099] In addition, during thermal runaway, the side and bottom surfaces of the housing material 312 may also be exposed to high temperatures or impacted by ejected material. For this reason, the housing 310 may include the laminate 100 on at least a portion of the wall surfaces of the housing material 312 and the lid material 314, and preferably in the lid material 314. The housing 310 may also include the laminate 100 on at least a portion of the wall surfaces. For example, the laminate 100 may be included in a position of the lid material 314 facing the terminals 322 that are likely to be directly hit by ejected material, and other positions may be formed of a different material. From the perspective of making the housing 310 less susceptible to damage or deformation due to heat and ejected material, it is preferable that the entire wall surfaces, for example, the entire lid material 314, be formed of the laminate 100.

[0100] The laminate 100 included in the wall surface may be a two-layer laminate as shown in Fig. 1A, or may be a laminate in which thermally conductive layers 120 are arranged on both sides of a flame-retardant layer 110 as shown in Fig. 1B. When the laminate is a two-layer laminate as shown in Fig. 1A, it is preferable that the flame-retardant layer 110 is arranged on the battery 320 side of the laminate 100, and the thermally conductive layer 120 is arranged on the opposite side of the battery 320.

[0101] The battery pack 300 can be used as a power source for a mobile object, a stationary storage battery for home use, etc. A mobile object having the battery pack 300 or a stationary storage battery having the battery pack 300 is unlikely to emit flames or ejected material outside the housing 310 even if the battery 320 experiences thermal runaway, making it highly safe.

[0102] 4. Other Embodiments The above description is an exemplary embodiment of this embodiment, and it goes without saying that the present invention is not limited to the above embodiment.

[0103] For example, in the above-described embodiment, the reinforcing fibers 112 contained in the flame-retardant layer 110 are preferably glass fibers, and the reinforcing fibers 122 contained in the thermally conductive layer 120 are preferably carbon fibers. However, other types of fibers may be used in the flame-retardant layer 110 and the thermally conductive layer 120. Furthermore, the reinforcing fibers contained in the flame-retardant layer 110 and the thermally conductive layer 120 may be reinforcing fibers of the same material or different materials.

[0104] In the above-described embodiment, it is preferable that the matrix resin 114 contained in the flame-retardant layer 110 and the matrix resin 124 contained in the thermally conductive layer 120 are both polypropylene. However, other types of resins may be used for the flame-retardant layer 110 and the thermally conductive layer 120. The matrix resins contained in the flame-retardant layer 110 and the thermally conductive layer 120 may be resins of the same material or resins of different materials.

[0105] In the above-described embodiment, the flame-retardant layer 110 includes the reinforcing fibers 112, which are randomly arranged short fibers, and the thermally conductive layer 120 includes an orientation layer including the reinforcing fibers 122 oriented in one direction or multiple directions. However, the flame-retardant layer 110 may be formed of an orientation layer including a flame retardant in the matrix resin 114, or the thermally conductive layer 120 may include the reinforcing fibers 122, which are randomly arranged short fibers.

[0106] The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

[0107] 1. Materials The following materials were used. (Raw Materials) Glass fiber masterbatch (GF-PP): Mostron L-5071PL9 manufactured by Prime Polymer Co., Ltd. (glass fiber content: 50% by mass, polypropylene 50% by mass) Phosphorus-based flame retardant masterbatch (FR-PP): MB32B manufactured by JLS (phosphorus-based flame retardant: 75% by mass (melamine polyphosphate: concentration 39% by mass, polyphosphoric acid salt compound: concentration 36% by mass), polypropylene: 25% by mass) Polypropylene (PP): J137G manufactured by Prime Polymer Co., Ltd. (homopolypropylene, MFR at 230°C and 2.16 kg load in accordance with ASTM D1238: 30 g / 10 min) CF-UD sheet (sheet containing carbon fibers oriented in one direction and polypropylene impregnated into the carbon fibers): TAFNEX manufactured by Mitsui Chemicals, Inc. (carbon fiber content: 67% by mass, polypropylene: 33% by mass) GF-UD sheet (a sheet containing glass fibers oriented in one direction and polypropylene (resin) impregnated into the glass fibers): MCP1238 (glass fiber content: 75% by mass, polypropylene (resin): 25% by mass), manufactured by Maruhachi Co., Ltd.

[0108] 2. Preparation of Test Pieces 2-1. Test Piece 1 60 parts by mass of GF-PP, 33 parts by mass of FR-PP, and 7 parts by mass of PP were dry-blended to obtain Raw Material Mixture 1. Raw Material Mixture 1 was placed in an injection molding machine (JSW Corporation, 280E II-SP injection molding machine) and injection molded at a barrel temperature of 220°C, an injection speed of 12 mm / s, a back pressure of 2 MPa, and a mold temperature of 65°C to obtain Plate 1, which was a flame-retardant layer. The dimensions of Plate 1 were 310 mm x 200 mm x 2 mm.

[0109] A 200 mm x 200 mm area was cut from the center of the flat plate 1 to form the flat plate test piece 1. Twelve CF-UD sheets were stacked on one side of the cut flat plate test piece 1, and press molding was performed using a press molding machine (Mini Test Press-10, manufactured by Toyo Seiki Co., Ltd.). The CF-UD sheets were stacked so that the carbon fiber orientation direction was [0° / 45° / 90° / 0° / 45° / 90° / 90° / 45° / 0° / 90° / 45° / 0°] from the flat plate test piece 1 side. The press molding involved preheating at a temperature of 180°C and a pressure of 0.5 MPa for 4 minutes to melt the resin components, followed by pressurization at a temperature of 180°C and a pressure of 5 MPa for 2 minutes. This resulted in a laminate in which the CF-UD sheet (thermal conductive layer) was fused to the flat plate test piece 1 (flame retardant layer). A test piece 1 having a thickness of 3.8 mm (flame-retardant layer: 2.0 mm, thermally conductive layer: 1.8 mm) was obtained. The thermal conductivity of the surface of the thermally conductive layer was measured by the laser flash method (lamella method) and was found to be 1.18 W / m·K.

[0110] 2-2. Test Piece 2: This is a laminate in which a CF-UD sheet (thermal conductive layer) was fused to a flat test piece 1 (flame retardant layer) in the same manner as test piece 1, except that two CF-UD sheets were placed on each side of flat test piece 1 so that the carbon fiber orientation was at 0° / 90° from the flat test piece 1 side, and then press-molded. Test piece 2 was obtained with a thickness of 2.6 mm (flame retardant layer: 2.0 mm, thermal conductive layer: 0.3 mm each). The thermal conductivity of the surface of the thermal conductive layer was measured using the laser flash method (lamella method) and found to be 1.18 W / m·K.

[0111] 2-3. Test Piece 3 47 parts by mass of FR-PP and 53 parts by mass of PP were dry-blended to obtain Raw Material Mixture 2. Plate 2, which is a flame-retardant layer, was obtained in the same manner as Plate 1, except that Raw Material Mixture 2 was used. The dimensions of Plate 2 were 310 mm × 200 mm × 2 mm.

[0112] A 200 mm x 200 mm area was cut from the center of plate 2 to prepare plate test piece 2. Two CF-UD sheets were placed on each side of plate test piece 2 so that the carbon fiber orientation was 0° / 90° from plate test piece 1, and then press-molded in the same manner as test piece 1. This resulted in a laminate in which a CF-UD sheet (thermal conductive layer) was fused to plate test piece 2 (flame-retardant layer). Test piece 3, measuring 2.6 mm in thickness (flame-retardant layer: 2.0 mm, thermal conductive layer: 0.3 mm each), was obtained. The thermal conductivity of the surface of the thermal conductive layer was measured using the laser flash method (lamella method) and found to be 1.18 W / m·K.

[0113] 2-4. Test Piece 4: This laminate was prepared in the same manner as Test Piece 1, except that two GF-UD sheets were placed on each side of Flat Test Piece 1 so that the orientation of the glass fibers was 0° / 90° from the Flat Test Piece 1 side, and then press-molded. This was a laminate in which a GF-UD sheet (thermal conductive layer) was fused to Flat Test Piece 1 (flame-retardant layer). Test Piece 4 was obtained with a thickness of 2.8 mm (flame-retardant layer: 2.0 mm, thermal conductive layer: 0.4 mm each). The thermal conductivity of the surface of the thermal conductive layer was measured using the laser flash method (lamella method) and found to be 0.33 W / m·K.

[0114] 2-5. Test Piece 5: This is a laminate in which a CF-UD sheet knit (thermal conductive layer) was fused to a flat test piece 1 (flame retardant layer) in the same manner as test piece 1, except that a CF-UD sheet knit, obtained by weaving CF-UD sheets cut into tape-like shapes with the carbon fibers intersecting at right angles, was layered on both sides of the flat test piece 1 and press-molded. Test piece 2 was obtained, measuring 2.6 mm in thickness (flame retardant layer: 2.0 mm, thermal conductive layer: 0.3 mm each). The thermal conductivity of the surface of the thermal conductive layer was measured using the laser flash method (lamella method) and found to be 1.18 W / m K.

[0115] 2-6. Test Piece 6 A flat plate test piece to which no UD sheet had been fused was obtained in the same manner as in the production of Laminate 1, except that the thickness of the flat plate was 4 mm.

[0116] 2-7. Test Piece 7 A flat test piece to which no UD sheet had been fused, obtained in the same manner as in the preparation of Laminate 1, was designated as Test Piece 7.

[0117] 3. Evaluation In accordance with UL2596 (2022), 25 100% charged battery cells (Panasonic lithium-ion batteries (NCR18650B 3300mAh)) were placed in five rows of five in an iron box with internal dimensions of 100mm x 100mm x 80mm. A heater and thermocouple were attached to the cell (hereinafter referred to as the trigger cell) located in the center of the box, and the cell temperature was measured during the test. Sixteen 11mm diameter holes were drilled in the test specimen, and the gasket, test specimen, and iron fixing jig were placed on top of the box and fastened in that order. Test specimen 1 was positioned so that the flame-retardant layer faced the battery cell side. Thermocouples were attached to the inner and outer surfaces of the test specimen, and the surface temperature of the test specimen was measured during the test. The heater temperature was increased to cause thermal runaway.

[0118] 3-1. Heat resistance strength If no holes were formed in the test piece due to thermal runaway, it was rated as passed (◯), and if holes were formed, it was rated as failed (×).

[0119] 3-2. Heat dissipation The time from the start of thermal runaway until the surface temperature of the test piece dropped (temperature decay start time) was measured.

[0120] 3-3. Deformation Resistance After thermal runaway, the thickness of the test piece was measured for the area with no deformation and the area with the largest deformation in the thickness direction. The difference in thickness (deformation amount) between these areas was calculated. The thickness was measured using a micrometer manufactured by Mitutoyo Corporation.

[0121] The materials and compositions of test pieces 1 to 3, as well as the evaluation results, are shown in Table 1. In Table 1, "CF" stands for carbon fiber, "GF" for glass fiber, and "PP" for polypropylene. Furthermore, "one side" of the thermally conductive layer indicates that the thermally conductive layer was disposed on only one side of the flame-retardant layer, and "both sides" indicates that the thermally conductive layer was disposed on only one side of the flame-retardant layer. Test piece 7 did not withstand the thermal runaway test, so evaluation of heat dissipation and deformation resistance was not performed.

[0122]

[0123] As shown in Table 1, the laminate having the flame-retardant layer and the thermally conductive layer was resistant to thermal runaway, had high heat dissipation properties, and was less deformed by heat.

[0124] This application claims priority from Japanese Patent Application No. 2023-139989, filed August 30, 2023. The entire disclosures of the specification, claims, and drawings of that application as originally filed are incorporated herein by reference.

[0125] The present invention provides a laminate that is highly heat resistant and is also resistant to deformation at high temperatures and damage due to impact.

[0126] REFERENCE SIGNS LIST 100 Laminate 110 Flame retardant layer 112 Reinforced fiber 114 Matrix resin 120 Thermally conductive layer 120a, 120b Oriented layer 122 Reinforced fiber 124 Matrix resin 300 Battery pack 310 Housing 312 Storage material 314 Lid material 320 Battery 322 Terminal

Claims

1. A laminate comprising: a flame-retardant layer containing a resin composition including a flame retardant; and a thermally conductive layer containing reinforcing fibers and a matrix resin, wherein the thermally conductive layer has a thermal conductivity of 0.2 W / m K or more and 10 W / m K or less at its surface, or the reinforcing fibers are oriented in one direction or in multiple directions.

2. The laminate according to claim 1, wherein the heat conductive layer contains carbon fiber or glass fiber as the reinforcing fiber.

3. The laminate according to claim 1, wherein the thermally conductive layer is a layer in which the reinforcing fibers are oriented in one direction or in multiple directions.

4. The laminate according to claim 3, wherein the thermally conductive layer is a layer containing the reinforcing fibers oriented and arranged in a plurality of directions perpendicular to each other.

5. The laminate according to claim 3, wherein the layer containing the reinforcing fibers is formed from a sheet-like molding containing the reinforcing fibers oriented in one direction and the matrix resin impregnated into the reinforcing fibers.

6. The laminate according to claim 1, wherein the flame retardant layer comprises reinforcing fibers.

7. The laminate according to claim 6, wherein the flame-retardant layer contains glass fibers as the reinforcing fibers.

8. The laminate according to claim 6, wherein the flame retardant layer is a layer in which the reinforcing fibers are randomly arranged.

9. The laminate according to claim 1, wherein the thermally conductive layer contains a polyolefin as the matrix resin, and the flame-retardant layer contains a polyolefin.

10. The laminate according to claim 1, wherein the thermally conductive layer contains polypropylene as the matrix resin, and the flame-retardant layer contains polypropylene.

11. The laminate according to claim 1, which is a heat-resistant member, and the heat conductive layer is disposed on the side opposite to the side where heat is generated with respect to the flame-retardant layer.

12. A housing for housing a battery, comprising the laminate according to any one of claims 1 to 11 on at least a portion of its wall.

13. A housing for housing the battery according to claim 12, wherein the laminate is included in a lid material.

14. A battery pack comprising: a housing for housing the battery according to claim 12; and a battery housed in said housing.

15. A mobile object comprising the battery pack according to claim 14.

Images