Battery box sealing structure

Abstract

To provide a battery box that allows the sealing material to be held securely without misalignment. [Solution] A battery box in which a battery cover and a battery tray are joined via a facing region, wherein the battery cover is made of fiber-reinforced plastic comprising discontinuous reinforcing fibers and thermoplastic resin, the battery cover having a main body, a first reinforced portion, and a second reinforced portion, the first reinforced portion and the second reinforced portion protruding from the main body toward the facing region, a groove is formed by the first wall surface of the first reinforced portion, the second wall surface of the second reinforced portion, and the groove bottom surface between the first wall surface and the second wall surface, and at least one of the angle θ1 between the first wall surface and the groove bottom surface, or the angle θ2 between the second wall surface and the groove bottom surface, is less than 90 degrees.

Description

Technical Field

[0001] The present invention relates to a battery box using a battery cover which is a fiber reinforced plastic containing discontinuous reinforcing fibers and a thermoplastic resin, and a method for manufacturing the same.

Background Art

[0002] Fiber reinforced plastics using reinforcing fibers as reinforcing materials have high tensile strength and tensile modulus of elasticity, small linear expansion coefficient, excellent dimensional stability, and are also excellent in heat resistance, chemical resistance, fatigue resistance characteristics, wear resistance, etc. Therefore, fiber reinforced plastics using reinforcing fibers are widely applied to automobiles, sports and leisure, aerospace, general industrial uses, etc.

[0003] The invention described in Patent Document 1 relates to a battery box with high waterproofness. It is composed of a battery tray having a bottom wall on which a battery is placed and a peripheral side wall surrounding the periphery, and a battery cover covering it. A groove portion is formed on the upper surface of the peripheral side wall of the battery tray, and a sealing material is assembled in the groove portion. When the battery tray and the battery cover are fixed, the sealing material is sandwiched to ensure waterproofness. Further, the battery cover has a protrusion corresponding to the groove portion to press the sealing material. Furthermore, a frame-shaped frame is provided outside the peripheral side wall of the battery tray and is fixed by a flange portion and a fastening member.

[0004] The invention described in Patent Document 2 relates to a battery box for accommodating a driving battery of an electric vehicle. It includes a tray member for supporting a battery, a cover member fixed thereon by overlapping, and a gasket interposed between the two. The cover member has positioning pins, and the tray member has positioning holes into which the pins are inserted. The gasket is disposed in an annular groove portion and is compressed and deformed during joining to ensure waterproofness.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-194982 [Patent Document 2] Japanese Patent Publication No. 2012-124131 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the sealing material described in Patent Document 1 is fixed by being pressed by a projection, and the position of the sealing material is prone to shifting. Similarly, the gasket described in Patent Document 2 ensures waterproofness by compressing and deforming during joining, but this requires a gasket with a complex shape. [Means for solving the problem]

[0007] Therefore, the present invention aims to provide a battery box in which the battery cover is made of fiber-reinforced plastic, grooves are formed in the fiber-reinforced plastic, and the sealing material is gripped in these grooves, thereby allowing the sealing material to be gripped stably without displacement.

[0008] To solve the above problems, the present invention provides the following means. 1. A battery box in which a battery cover and a battery tray are joined via a facing region, wherein the battery cover is made of fiber-reinforced plastic containing discontinuous reinforcing fibers and thermoplastic resin, The battery cover has a main body, a first reinforced portion, and a second reinforced portion. The first reinforced portion and the second reinforced portion protrude from the main body portion toward the opposite region, A groove is formed by the first wall surface of the first build-up portion, the second wall surface of the second build-up portion, and the bottom surface of the groove between the first wall surface and the second wall surface. At least one of the angles θ1 between the first wall surface and the groove bottom surface, or the angle θ2 between the second wall surface and the groove bottom surface, is less than 90 degrees. Battery box. 2. The facing area is formed around the entire circumference of the battery cover. The battery box according to claim 1, wherein the groove is formed continuously around the entire circumference of the battery cover. 3. The battery box according to either 1 or 2, wherein a sealing material is placed in the groove and the sealing material is held by the first build-up portion and the second build-up portion. 4. The battery tray and the battery cover are joined together, so that the sealing material is sandwiched between the battery tray and the battery cover. A battery box as described in any one of items 1 to 3 above. 5. A battery box according to any one of 1 to 4, wherein, when the inside of the groove is observed, a thickened portion is formed between the first reinforced portion and the second reinforced portion. 6. The battery cover and the battery tray each have a flange portion, The flange portion of the battery cover and the flange portion of the battery tray are joined together to form the facing region. A battery box as described in any one of items 1 to 5 above. 7. A battery box according to any one of items 1 to 6 above, The angle θ1 and the angle θ2 are less than 90 degrees. Battery box. 8. The battery box according to any one of 1 to 7, wherein the weight-average fiber length of the discontinuous reinforcing fiber is 1 mm or more and 100 mm or less. 9. A battery box according to any one of items 1 to 8 above, which satisfies the following formula (1). Formula (1): t1×E>t1+t2 t1: Thickness of the fiber-reinforced plastic in the opposing region. t2: Clearance between the battery cover and the battery tray in the aforementioned facing area. E: Expansion rate of the fiber-reinforced plastic after 600 seconds of applying a burner flame to the surface of the fiber-reinforced plastic in the aforementioned facing region, such that the flame surface temperature is between 950°C and 1000°C. 10. The battery box according to 9, wherein when the battery box is heated, the fiber-reinforced plastic expands toward the facing region. 11. The battery box according to 10, wherein when the battery box is heated, the fiber-reinforced plastic expands, thereby sealing the sealing material with the fiber-reinforced plastic. 12. A method for manufacturing any one of the battery boxes described in 1 to 11 above, The battery cover is created by compression molding a plate-shaped composite material using a mold. The angle between the first wall surface and the groove bottom surface immediately after molding is pθ1. When the angle between the second wall surface and the groove bottom surface immediately after molding is pθ2, A method for manufacturing a battery box that satisfies at least one of the following conditions: pθ1 > θ1 or pθ2 > θ2. 13. A method for manufacturing a battery box as described in item 12 above, A method for manufacturing a battery box, wherein the mold has a first recess for forming the first build-up portion and a second recess for creating the second build-up portion, and the first recess and the second recess have a draft angle. [Effects of the Invention]

[0009] In the battery box of the present invention, the battery cover is made of fiber-reinforced plastic, and grooves are formed using the fiber-reinforced plastic. To allow the sealing material to be held, at least one of the angles θ1 between the first wall surface forming the groove and the groove bottom surface, or the angle θ2 between the second wall surface and the groove bottom surface, is less than 90 degrees, thus facilitating the gripping of the sealing material. [Brief explanation of the drawing]

[0010] [Figure 1]Schematic diagram showing the sealing structure in the battery box of the present invention. [Figure 2] Schematic diagram showing an example of a vehicle structure using the battery box of the present invention. [Figure 3] Enlarged view of the sealing structure portion in the battery box of the present invention. [Figure 4] Schematic diagram showing the sealing structure in a conventional battery box. [Figure 5] Schematic diagram showing a structure in which a thick portion is formed between the first build-up portion and the second build-up portion. [Figure 6] Schematic diagram of the lower mold for compression molding. [Figure 7] Schematic diagram showing the state where the sealing material is sealed. [Embodiments for Carrying Out the Invention]

[0011] [Reinforcing Fiber] In this specification, the reinforcing fiber is preferably at least one selected from the group consisting of carbon fiber, aramid fiber, and glass fiber. More preferably, the reinforcing fiber is carbon fiber or glass fiber.

[0012] [Reinforcing Fiber: Carbon Fiber] 1. Carbon Fiber in General As the carbon fiber used in the present invention, generally, polyacrylonitrile (PAN)-based carbon fiber, petroleum and coal pitch-based carbon fiber, rayon-based carbon fiber, cellulose-based carbon fiber, lignin-based carbon fiber, phenol-based carbon fiber, etc. are known, but in the present invention, any of these carbon fibers can be suitably used. Among them, in the present invention, it is preferable to use polyacrylonitrile (PAN)-based carbon fiber in terms of excellent tensile strength. As the PAN-based carbon fiber, for example, the carbon fiber "Tenax" (registered trademark) STS40-24KS (average fiber diameter 7 μm) manufactured by Teijin Limited can be used.

[0013] 2. Sizing Agent for Carbon Fiber The carbon fibers used in the present invention may have a sizing agent attached to their surface. When using carbon fibers with a sizing agent attached, the type of sizing agent can be appropriately selected according to the type of carbon fiber and the type of resin used in the composite material, and is not particularly limited.

[0014] [Reinforced fiber: glass fiber] The present invention will now describe the case where the reinforcing fiber used is glass fiber. 1. All types of glass fibers The glass fibers used in this invention may be any glass fibers that are generally referred to as glass fibers. The glass composition is not particularly limited to A glass, C glass, E glass, etc., and may contain components such as TiO2 and P2O5 depending on the circumstances. As a glass fiber, for example, RV P204-4800TEX manufactured by Owens Corning can be used.

[0015] 2. Glass fiber sizing agent The glass fibers used in the present invention may have a sizing agent attached to their surface. When using glass fibers with a sizing agent attached, the type of sizing agent can be appropriately selected according to the type of glass fiber and the type of resin, and is not particularly limited. Preferably, glass fibers that have been pre-treated with conventionally known coupling agents such as organosilane compounds, organotitanium compounds, organoborane compounds, and epoxy compounds can be used.

[0016] 3. Single-ended roving and multi-ended roving In the fiber-reinforced plastic of the present invention, it is preferable that single-end roving glass fibers GFs and multi-end roving glass fibers GFm are mixed in a volume ratio of GFm:GFs of 50:50 to 90:10. If the proportion of GFm is 50% or more, the work rate can be easily kept below the upper limit. If the proportion of GFm is 90% or less, the work rate can be kept below the lower limit.

[0017] Multi-end roving refers to roving where the ends of the glass strands are not aligned. In multi-end roving, the glass fibers have multiple ends. Single-end roving refers to roving where the ends of the glass strands are aligned to a single point. In single-end roving, the glass fibers have only one end.

[0018] [Reinforcement fibers: Dispersed in the in-plane direction] It is preferable that the discontinuous reinforcing fibers contained in the fiber-reinforced plastic are dispersed in the in-plane direction. Furthermore, the fiber-reinforced plastic of the present invention is molded from a composite material containing discontinuous fibers and a thermoplastic resin. Therefore, it is more preferable that the discontinuous reinforcing fibers contained in the composite material are also dispersed in the in-plane direction. Dispersion of discontinuous reinforcing fibers in the in-plane direction means that the fiber axes of the discontinuous reinforcing fibers are dispersed so as to be oriented in the in-plane direction. It is preferable that the angle that the fiber axes of the discontinuous reinforcing fibers make with the in-plane direction is 45° or less.

[0019] 1. In-plane direction The composite material used to manufacture fiber-reinforced plastics is preferably in the form of a sheet. The in-plane direction refers to an undefined direction of parallel planes perpendicular to the thickness direction of the composite material.

[0020] 2. Random distribution in 2.2 dimensions It is preferable that the discontinuous reinforcing fibers are randomly dispersed in a two-dimensional direction in the in-plane direction. When the composite material is press-molded without flowing (non-flow molding), the shape of the reinforcing fibers is largely maintained before and after molding. In the case of non-flow molding, it is preferable to orient the discontinuous reinforcing fibers contained in the composite material in a two-dimensional random manner so that the discontinuous reinforcing fibers contained in the fiber-reinforced plastic (molded body) formed from the composite material are similarly dispersed in a two-dimensional random manner in the in-plane direction.

[0021] Here, "randomly dispersed in two dimensions" means that the discontinuous reinforcing fibers are oriented in a disordered manner within the in-plane direction of the fiber-reinforced plastic (or composite material), rather than in a specific direction such as one direction, and are arranged within the sheet surface without exhibiting a particular direction overall. The fiber-reinforced plastic (or composite material) obtained using these randomly dispersed discontinuous reinforcing fibers is substantially isotropic, without anisotropy within the plane.

[0022] The degree of two-dimensional random orientation is evaluated by determining the ratio of the tensile moduli in two mutually orthogonal directions. If the ratio (Eδ) obtained by dividing the larger of the measured tensile moduli in any direction and in a direction orthogonal thereto by the smaller value is 5 or less, more preferably 2 or less, and even more preferably 1.5 or less, then it can be evaluated that the discontinuous reinforcing fibers are dispersed randomly in two dimensions. When the fiber-reinforced plastic includes curved surfaces, a good method for evaluating the two-dimensional random dispersion in the in-plane direction is to heat it above the softening temperature to return it to a flat plate shape and then solidify it. After that, by cutting out a test piece and determining the tensile modulus, the random dispersion state in the two-dimensional direction can be confirmed.

[0023] [Reinforcement fiber: Fiber length] The weight-average fiber length of the discontinuous reinforcing fibers is preferably between 1 mm and 100 mm. Since the weight-average fiber length does not change before and after molding in composite materials and fiber-reinforced plastics (molded articles), the weight-average fiber length Lw of the reinforcing fibers contained in the fiber-reinforced plastic (molded article) can be determined by examining the weight-average fiber length of the reinforcing fibers contained in the composite material.

[0024] The lower limit of the weight-average fiber length of the discontinuous reinforcing fibers is preferably 5 mm or more, and more preferably 10 mm or more. Conversely, the upper limit of the weight-average fiber length is preferably 80 mm or less, and more preferably 70 mm or less. When the weight-average fiber length is 1 mm or more, the mechanical strength of the resulting fiber-reinforced plastic does not tend to decrease, which is preferable. When the weight-average fiber length is 100 mm or less, the fluidity of the material does not tend to decrease when the composite material is manufactured by press molding, and it is easier to create the composite material into the desired shape. The preferred weight-average fiber length range for the discontinuous reinforcing fibers is 5 mm to 80 mm, and more preferably 10 mm to 60 mm.

[0025] [Reinforcement fibers: Number-average fiber length Ln and weight-average fiber length Lw] Generally, if the fiber length of each reinforcing fiber is Li, the number-average fiber length Ln and the weight-average fiber length Lw can be calculated using the following equations (X) and (Y). The units for the number-average fiber length Ln and the weight-average fiber length Lw are mm.

[0026]

number

[0027] When the fiber length is constant, the number-average fiber length and the weight-average fiber length will be the same value. Reinforcement fibers can be extracted from fiber-reinforced plastics, for example, by heat treatment at approximately 500°C for 1 hour, followed by removal of the resin in the furnace.

[0028] The average fiber length can be determined, for example, by measuring the fiber length of 100 randomly selected fibers from fiber-reinforced plastic to the nearest 1 mm using a caliper or similar tool, and then calculating it based on formula (X).

[0029] If short fibers that cannot be measured with calipers are present, the resin is removed, and the resulting reinforced fibers are placed in water containing a surfactant and thoroughly stirred using ultrasonic vibration. A random sample of the stirred dispersion is taken using a measuring spoon to obtain an evaluation sample, and the length of 3000 fibers is measured using a Nireco Luzex AP image analysis device. Using the measured fiber lengths, the number-average fiber length Ln and weight-average fiber length Lw can be determined in the same manner as the above-mentioned equations (X) and (Y).

[0030] [Reinforcement fiber: volume percentage] The volume percentage (Vf) of reinforcing fibers in fiber-reinforced plastics can be calculated using the following formula (Z). Reinforcement fiber volume ratio (Vf) = 100 × reinforcement fiber volume / (reinforcement fiber volume + resin volume) Equation (Z) There are no particular limitations on the volume percentage of reinforcing fibers, but the volume percentage of reinforcing fibers (Vf) is preferably 10 to 60 Vol%, more preferably 20 to 50 Vol%, and even more preferably 25 to 45 Vol%.

[0031] [Analysis of the volume percentage (Vf) of reinforcing fibers] There are no limitations to the analysis of the reinforcing fiber volume ratio, but it is recommended to measure it as follows: Cut a sample from the fiber-reinforced plastic, burn off the thermoplastic resin in a furnace at 500°C for 1 hour, and weigh the sample before and after treatment to calculate the mass of the reinforcing fiber and resin. Next, calculate the volume of the reinforcing fiber by dividing the mass of the reinforcing fiber by the density of the reinforcing fiber, and calculate the volume of the thermoplastic resin by dividing the mass of the thermoplastic resin by the density of the resin. Next, calculate the ratio Vf of the volume of the reinforcing fiber to the total volume of the reinforcing fiber and thermoplastic resin.

[0032] [Thermoplastic resin] The type of thermoplastic resin used in this invention is not particularly limited, and any resin having a desired softening point or melting point can be appropriately selected and used. Typically, thermoplastic resins with a softening point in the range of 80°C to 350°C, preferably 100°C to 350°C, and more preferably 180°C to 350°C are used, but the invention is not limited thereto.

[0033] Examples of thermoplastic resins include polyolefin resins, polystyrene resins, polyamide resins, polyester resins, polyacetal resins (polyoxymethylene resins), polycarbonate resins, (meth)acrylic resins, polyarylate resins, polyphenylene ether resins, polyimide resins, polyethernitrile resins, phenoxy resins, polyphenylene sulfide resins, polysulfone resins, polyketone resins, polyetherketone resins, thermoplastic urethane resins, fluoropolymer resins, and thermoplastic polybenzimidazole resins.

[0034] The thermoplastic resin used in the fiber-reinforced plastic of the present invention may be of one type or two or more types. Examples of using two or more thermoplastic resins in combination include, but are not limited to, a combination of thermoplastic resins with different softening points or melting points, or a combination of thermoplastic resins with different average molecular weights. When using thermoplastic resins, it is more preferable to use polyolefin resins, and even more preferable to use polypropylene resins.

[0035] [Flame retardant] 1. Overview The fiber-reinforced plastic of the present invention preferably contains a flame retardant. The flame retardant is not particularly limited, and examples include phosphorus-based flame retardants, bromine-based flame retardants, and antimony-based flame retardants. Among these, phosphorus-based flame retardants are preferred from the viewpoint of improving flame resistance. Furthermore, in a classification focusing on the mechanism of action of the flame retardant, it is preferable that the flame retardant be an intomessecent flame retardant from the viewpoint of improving flame resistance.

[0036] 2. Phosphorus-based flame retardants 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.

[0037] The phosphorus-based flame retardant may be any known type, such as (poly)phosphate or (poly)phosphate ester. Here, "(poly)phosphate" refers to a phosphate or polyphosphate, and "(poly)phosphate ester" refers to a phosphate ester or polyphosphate ester. It is preferable that the phosphorus-based flame retardant is solid at 80°C.

[0038] 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 orphosphate, calcium phosphate, and magnesium phosphate.

[0039] 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.

[0040] Examples of commercially available phosphorus-based flame retardants include ADEKA® FP-2100J, FP-2200, FP-2500S (manufactured by ADEKA Corporation), ADEKA® FP-2100 JC, and Clariant's Exolit® AP462 and Exolit OP1230.

[0041] 3. Intomesse-type flame retardants Intomescent flame retardants are flame retardants that suppress the combustion of materials by forming a surface expansion layer (intumescent) that prevents radiant heat from the combustion source and the diffusion of combustion gases and smoke from the burning material to the outside.

[0042] Intomessent flame retardants cause the resin composition to form a surface expansion layer (intomescent) which is foamed char when burned. The formation of this surface expansion layer suppresses the diffusion of decomposition products and heat transfer, resulting in excellent flame retardancy. Examples of intomessent flame retardants include salts of (poly)phosphate and nitrogen compounds, specifically ammonium salts and amine salts of (poly)phosphate.

[0043] 4. Brominated flame retardants 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.

[0044] 5. Antimony-based flame retardants 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.

[0045] [Flame retardant content] The flame retardant content in fiber-reinforced plastics is preferably 1 to 50 parts by mass per 100 parts by mass of thermoplastic resin. More preferably, it is in the range of 1 to 30 parts by mass, and even more preferably, in the range of 5 to 25 parts by mass. When the amount is 1 part by mass or more, good flame retardancy can be imparted to the fiber-reinforced plastic, and good flame shielding properties can be obtained. On the other hand, when the amount of flame retardant is 50 parts by mass or less, the moldability is further improved.

[0046] [Dispersant] 1. Overview As a dispersant, it is sufficient that the flame retardant can be dispersed in the thermoplastic resin, and there are no particular limitations, but polymer dispersants can be suitably used in terms of compatibility with the resin. Preferably, a dispersant that can disperse the flame retardant in polypropylene resin can be used. As a polymer dispersant, a polymer dispersant having a functional group is preferred, and from the viewpoint of dispersion stability, polymer dispersants having functional groups such as carboxyl groups, phosphate groups, sulfonic acid groups, primary, secondary or tertiary amino groups, quaternary ammonium bases, pyridine, pyrimidine, pyrazine, and other nitrogen-containing heterocycle-derived groups are preferred.

[0047] 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.

[0048] 2. The necessity of dispersants The fiber-reinforced plastic (or composite material) in this invention does not necessarily need to contain a dispersant. It is not necessary as long as flame retardancy can be ensured.

[0049] [Other agents] The fiber-reinforced plastic of the present invention may contain additives such as various fibrous or non-fibrous fillers of organic or inorganic fibers, UV resistant agents, stabilizers, mold release agents, pigments, softeners, plasticizers, and surfactants, to the extent that the objectives of the present invention are not impaired.

[0050] [Battery box] 1. Battery cover and battery tray Figure 2 is a cross-sectional view showing an example of a battery box. As shown in Figure 2, the battery 206 is housed in a battery box comprising a battery tray 208 and a battery cover 207. It is preferable that the battery box is for use in a vehicle.

[0051] 2. Face-to-face area The battery cover and battery tray of this invention are joined together via opposing regions. The opposing region is the region for joining the battery cover and the battery tray. Preferably, this region is one in which the clearance between the battery cover and the battery tray is less than or equal to the height of the first reinforced portion and the height of the second reinforced portion.

[0052] More specifically, the area where the clearance between the battery cover and the battery tray is 10 mm or less may be defined as the facing area, or the area where the clearance between the battery cover and the battery tray is 5 mm or less may be defined as the facing area. Figure 1 is a schematic diagram showing that the battery cover 101 and the battery tray 102 form a facing area 103. The battery cover 101 and the battery tray 102 face each other in the facing area 103 and are fastened together by bolts 104.

[0053] As shown in Figure 1, the battery cover 101 and the battery tray 102 each have a flange portion 105 of the battery cover 101 and a flange portion 106 of the battery tray 102, and it is preferable that the flange portion 105 of the battery cover 101 and the flange portion 106 of the battery tray 102 are joined together to form a facing region.

[0054] Furthermore, in the opposing region, the battery cover and the battery tray do not need to be in close contact. In particular, as in the present invention, since there is a first build-up portion and a second build-up portion, there is a certain amount of space between the battery cover 101 and the battery tray 102. When fastening the flange portion 105 of the battery cover 101 and the flange portion 106 of the battery tray 102 with bolts 104, once the bolts 104 are tightened to a certain extent, the sealant 107 fills the groove portion 307. To complete the tightening of the bolts 104 in the filled state, (1) a collar 108 can be inserted around the bolts 104 in the opposing region 103, or (2) the thickness of the first or second member can be increased. This allows the fastening to be completed when the lowest point of the first or second build-up portion contacts the flange 106.

[0055] 3. Sealant A sealing material 107 is placed in the opposing area 103. Commonly used sealing materials include silicone, polyurethane, and epoxy resin. The sealing material used in the battery box is used for (1) waterproofing and dustproofing to prevent water and dust from entering the battery box and damaging the battery and other electronic components, and (2) vibration and shock absorption to protect the battery from vibrations and shocks that occur during the use of the vehicle or equipment. In addition, since batteries generate heat during use, the sealing material needs to withstand high temperatures (heat resistance is required) and must be resistant to chemicals that may leak from the battery (chemical resistance is required).

[0056] There are no particular limitations on the size or shape of the sealing material, but a solid or semi-solid sealing material with a height of 6 mm or more is preferable because it ensures sufficient compressibility and reassembly capability.

[0057] [Holding the sealing material with the battery cover] 1. Overview The battery box of the present invention will be explained with reference to Figure 3. Figure 3 is a magnified view of the portion of the battery box in Figure 1 in which the battery cover grips the sealing material.

[0058] The battery cover has a main body 303, a first reinforced portion 301, and a second reinforced portion 302. The first build-up portion 301 and the second build-up portion 302 protrude from the main body portion 303 toward the opposite region. A groove portion 307 is formed by the first wall surface 304 of the first build-up portion 301, the second wall surface 305 of the second build-up portion 302, and the groove bottom surface 306 located between the first wall surface 304 and the second wall surface 305. At least one of the angles θ1 between the first wall surface 304 and the groove bottom surface 306, or the angle θ2 between the second wall surface 305 and the groove bottom surface 306, is less than 90 degrees.

[0059] 2. First and second layers of thickened material There are no particular restrictions on the size of the first and second meat mounds, The height of the first and second build-up portions is preferably 1 mm to 10 mm, more preferably 2 mm to 8 mm, and even more preferably 4 mm to 6 mm.

[0060] Of the reinforced concrete portions forming the first reinforced concrete portion and the second reinforced concrete portion, the surfaces on which the first reinforced concrete portion and the second reinforced concrete portion face each other are called the first wall surface 304 and the second wall surface 305, respectively. The groove bottom surface 306 refers to the bottom surface located between the first wall surface 304 and the second wall surface 305.

[0061] 3. Groove Preferably, a sealing material is placed in the groove 307, and the sealing material is held in place by the first build-up portion and the second build-up portion. The groove 307 may be partially provided in the battery cover. If the groove 307 is partially provided in the battery cover 101, it is possible to suppress the detachment of the sealing material after it has been placed in the battery cover until it is joined to the battery tray. In addition, if the groove 307 is partially provided in the battery cover 101, the force required to remove the battery cover from the mold can also be reduced.

[0062] On the other hand, the opposing region may be formed around the entire circumference of the battery cover, and the groove 307 may be formed continuously around the entire circumference of the battery cover 101. By forming the groove continuously around the entire circumference, the battery cover can grip the sealing material more securely.

[0063] The depth of the groove is preferably 1 mm to 10 mm, more preferably 2 mm to 8 mm, and even more preferably 4 mm to 6 mm.

[0064] 4. Preventing the sealant from falling off. The sealing material of the present invention can be securely gripped because at least one of the angles θ1 between the first wall surface 304 and the groove bottom surface 306, or the angle θ2 between the second wall surface 305 and the groove bottom surface 306, is less than 90 degrees.

[0065] As shown in Figure 4, if both the angle θ1 between the first wall surface 304 and the groove bottom surface 306, or the angle θ2 between the second wall surface 305 and the groove bottom surface 306, are 90 degrees or greater, the sealing material will fall off even if it is gripped by the battery cover. Therefore, it becomes difficult to grip the sealing material onto the battery cover before assembling the battery tray and battery cover. A preferred angle θ1 is 85 degrees or less, and a more preferred angle θ1 is 80 degrees or less. A preferred angle θ2 is 85 degrees or less, and a more preferred angle θ2 is 80 degrees or less. If at least one of angles θ1 and θ2 is less than 90 degrees, the other angle does not necessarily have to be less than 90 degrees. For example, if angle θ1 is 85 degrees, angle θ2 may be 91 degrees. In other words, it is preferable that angle θ1 + angle θ2 < 180 degrees, more preferable that angle θ1 + angle θ2 < 175 degrees, and even more preferable that angle θ1 + angle θ2 < 170 degrees.

[0066] Furthermore, in order to increase the gripping force of the sealing material on the battery cover, it is preferable that angles θ1 and θ2 be less than 90 degrees, more preferably 85 degrees or less, and even more preferably 80 degrees or less.

[0067] 5.Thick part When observing the inside of the groove, it is preferable that a thickened portion 501, as shown in Figure 5, is formed between the first and second reinforced portions. By providing such a thickened portion 501, it is easy to make at least one of the angles θ1 between the first wall surface 304 and the groove bottom surface 306, or the angle θ2 between the second wall surface 305 and the groove bottom surface 306, less than 90 degrees. The thickened portion 501 makes it easy to form such that pθ1 > θ1 or pθ2 > θ2. It is preferable that the thickened portion 501 extends continuously from the groove bottom surface 306.

[0068] [Sealant clamping] After assembling the battery cover and battery tray to form a battery box, it is preferable that a sealing material is sandwiched between the battery tray and the battery cover when the battery tray and battery cover are joined together. This ensures that the battery box is airtight and watertight.

[0069] [Sealing by expansion of fiber-reinforced plastic] 1. Overview In some cases, fire-resistant agents are added to sealants to improve their fire resistance in the event of a fire occurring in a battery stored inside a battery box. However, sealants mixed with additives to improve fire resistance tend to lose elasticity, which reduces the airtightness of the battery box.

[0070] Therefore, the inventors devised a method to seal the battery with fiber-reinforced plastic when exposed to flames, in order to prevent damage to the sealing material in the event of a fire while maintaining the elasticity of the sealing material. In other words, in the battery box of the present invention, it is preferable that the sealing material is sealed by the fiber-reinforced plastic as the fiber-reinforced plastic expands when heated. Figure 7 shows the sealing of the sealing material.

[0071] 2. Sealing mechanism 2.1 Overview The battery box of the present invention preferably satisfies the following formula (1). Formula (1): t1×E>t1+t2 Here t1: Thickness of fiber-reinforced plastic in the facing area t2: Clearance between the battery cover and battery tray in the face-to-face area. E: Expansion rate of the fiber-reinforced plastic after 600 seconds of applying a burner flame to the surface of the fiber-reinforced plastic in the aforementioned facing region, such that the flame surface temperature is between 950°C and 1000°C. That is the case.

[0072] 2.2 Thickness t1 of fiber-reinforced plastic in the facing area The battery cover of the present invention is made of fiber-reinforced plastic. Therefore, the thickness t1 of the fiber-reinforced plastic in the facing region is the thickness of the battery cover 101 in the facing region as shown in Figure 1. If the thickness is not constant, the average value of 10 measurements of the thickness of the fiber-reinforced plastic in the facing region may be used. However, the thickness of the first and second reinforced portions is not included in the thickness t1 of the fiber-reinforced plastic.

[0073] The thickness t1 of the fiber reinforced plastic in the present invention is Formula (2) 1.3 mm < t1 < 10.0 mm is preferred. Formula (2) is preferably Formula (2a), more preferably Formula (2b), and even more preferably Formula (2c). Formula (2a) 1.4 mm < t1 < 8.0 mm, and more preferably Formula (2b) 1.5 mm < t1 < 7.0 mm, and even more preferably Formula (2c) 1.5 mm < t1 < 6.0 mm.

[0074] If t1 is 1.3 mm or more, the fiber reinforced plastic can be sufficiently expanded during flame exposure. If t1 is 10.0 mm or less, when using the fiber reinforced plastic as a battery cover, the thickness can be reduced and weight can be reduced, and in the interior design of an automobile, the design space where the battery box is installed can be expanded.

[0075] 2.3 Clearance between the battery cover and the battery tray in the facing area The clearance between the battery cover and the battery tray in the facing area means the distance of the gap on the facing surface of the battery cover and the battery tray. As shown in FIG. 7, the battery cover and the battery tray are not completely in close contact, and there is a slight gap. The distance of 703 in FIG. 7 is defined as the clearance between the battery cover and the battery tray.

[0076] 2.4 Expansion rate E The expansion rate E is the expansion rate of the fiber reinforced plastic after 600 seconds when the surface of the fiber reinforced plastic in the facing area is brought into contact with a burner so that the flame surface is 950 °C or more and 1000 °C or less.

[0077] Apply a burner flame to the material so that the flame surface reaches a temperature between 950°C and 1000°C. After 600 seconds, if the fiber-reinforced plastic ignites and burns, extinguish the flame after another 600 seconds and observe the result. Observe the area where the burner flame directly contacted the material.

[0078] The expansion coefficient E is given by the following equation (3). Equation (3) E = t3 / t1 t1: Thickness of fiber-reinforced plastic in the facing area t3: The thickness of the fiber-reinforced plastic after 600 seconds of applying a burner flame to the surface of the fiber-reinforced plastic in the facing area, with the flame surface temperature between 950°C and 1000°C.

[0079] 2.5 Encapsulation In other words, by satisfying equation (1), if there is a fire 702 as shown in Figure 7, the temperature of the fiber-reinforced plastic in the opposing region rises and it expands. The expanded portion is shown as 701 in Figure 7. As a result, the sealant 107 is sealed by the expanded portion 701 and is not exposed to the flame. Consequently, the temperature of the sealant is less likely to rise, and thermal degradation can be suppressed. Note that, as shown in Figure 7, it is not necessarily the case that all surfaces of the sealant are sealed. It is sufficient for the sealant to be at least partially sealed to prevent heating from the direction exposed to the flame.

[0080] 3. Direction of expansion 3.1 When the battery box is heated, it is preferable that the fiber-reinforced plastic expands toward the opposite region. The expanded portion 701 in Figure 7 is expanding toward the opposite region. 3.2 When the battery box is heated, the fiber-reinforced plastic may expand in the direction of the normal to the opposite region. The direction of the normal to the opposite region is the negative direction of the Y-axis in Figure 7. In other words, the "direction of the normal to the opposite region" refers to the direction perpendicular to the opposite region, and the direction directly above or directly below the opposite region is the direction of the normal to the opposite region. In Figure 7, the expanded portion is formed when the fiber-reinforced plastic expands in the direction normal to the opposite side (Y direction), creating an expanded portion 609. 3.3 When the battery box is heated, the fiber-reinforced plastic may expand in a direction along the opposing surface of the opposing area (not shown).

[0081] 4. Fiber-reinforced plastics For the sealant to be sealed by the fiber-reinforced plastic due to the expansion of the fiber-reinforced plastic when the battery box is heated, the battery cover must be made of fiber-reinforced plastic containing discontinuous fibers and thermoplastic resin.

[0082] The battery tray may be made of metal such as iron or aluminum, or of fiber-reinforced plastic containing continuous fibers. Both the battery cover and the battery tray may be made of fiber-reinforced plastic containing discontinuous fibers and thermoplastic resin.

[0083] [Springback of composite materials and fiber-reinforced plastics] 1. Springback of composite materials To perform cold-press molding using composite materials, it is necessary to preheat and heat the composite material to a predetermined temperature to soften and melt it. When a composite material containing discontinuous reinforcing fibers with a weight-average fiber length of 1 mm to 100 mm (especially when the reinforcing fibers are in a mat-like state) is preheated, the thermoplastic resin becomes plastic. Due to the springback of the discontinuous reinforcing fibers, the preheated composite material expands, and the bulk density of the composite material changes. When the bulk density changes during preheating, the composite material becomes porous, increasing its surface area, and air flows into the interior of the composite material, accelerating the thermal decomposition of the thermoplastic resin. Here, the springback rate is the value obtained by dividing the thickness of the composite material after preheating by the thickness of the composite material before preheating.

[0084] The springback rate tends to increase when the reinforcing fiber bundles in composite materials become highly open (single-fiber rich) or when the fiber length increases.

[0085] In this invention, it is preferable that the springback rate of the composite material is between 1.05 and 8.0. If the springback rate of the composite material is 8.0 or less, it is possible to prevent the fiber-reinforced plastic (battery cover) molded from the composite material from expanding too much during combustion and coming into contact with the battery. Conversely, if the springback rate is 1.05 or higher, the composite material using the composite material expands easily when heated, thus providing an insulating effect.

[0086] A preferred springback ratio for composite materials is 2.0 to 8.0, a more preferred springback ratio for composite materials is 3.0 to 7.0, and an even more preferred springback ratio is 4.0 to 6.0.

[0087] 2. Springback of fiber-reinforced plastics The fiber-reinforced plastic (battery cover) of the present invention preferably has a springback rate of 1.05 to 8.0, similar to composite materials. A preferred springback rate for fiber-reinforced plastic is 2.0 to 8.0, a more preferred springback rate is 3.0 to 7.0, and an even more preferred springback rate is 4.0 to 6.0. If the springback rate of the fiber-reinforced plastic is 1.05 or higher, the composite material expands easily when heated, making it easier to obtain a heat insulating effect.

[0088] [Manufacturing method for fiber-reinforced plastic (battery cover)] The battery cover of the present invention is a fiber-reinforced plastic containing discontinuous reinforcing fibers and a thermoplastic resin. The following describes a method for manufacturing the fiber-reinforced plastic battery cover.

[0089] Here, the composite material is a material used to create fiber-reinforced plastic, and the composite material is preferably in the form of a flat plate. On the other hand, fiber-reinforced plastic is a molded product and has a defined shape. In this invention, the battery cover is made of fiber-reinforced plastic, but both the battery cover and the battery tray may be made of fiber-reinforced plastic.

[0090] 1. Cold press (molding) method In manufacturing the fiber-reinforced plastic (molded article) of the present invention, press molding (sometimes called compression molding) is used as the molding method, and in particular, press molding using cold press is preferred. In the cold press molding method, for example, a composite material heated to a first predetermined temperature is placed into a mold set to a second predetermined temperature, and then pressurized and cooled.

[0091] Specifically, if the thermoplastic resin constituting the composite material is crystalline, the first predetermined temperature is above the melting point of the thermoplastic resin, and the second predetermined temperature is below the melting point. If the thermoplastic resin is amorphous, the first predetermined temperature is above the glass transition temperature of the thermoplastic resin, and the second predetermined temperature is below the glass transition temperature.

[0092] In other words, the cold press molding method includes at least the following steps A-1) to A-2). Step A-1) A step of heating the composite material to a temperature above the melting point of the thermoplastic resin or below the decomposition temperature of the thermoplastic resin if the thermoplastic resin is crystalline, or above the glass transition temperature of the thermoplastic resin or below the decomposition temperature if the thermoplastic resin is amorphous. Step A-2) A step in which the composite material heated in Step A-1) above is placed in a mold whose temperature is controlled to be below the melting point if the thermoplastic resin is crystalline, or below the glass transition temperature if the thermoplastic resin is amorphous, and then pressurized. By performing these steps, the molding of the composite material can be completed.

[0093] Each of the above steps must be performed in the order listed above, but other steps may be included between each step. Other steps include, for example, a forming step performed before step A-2), in which a different forming die than the one used in step A-2) is used to pre-form the shape of the cavity of the forming die.

[0094] 2. Hot Press (Molding) Method The hot press (molding) method involves, for example, placing a composite material into a mold, applying pressure while raising the temperature of the mold to a first predetermined temperature, and then cooling the mold to a second predetermined temperature. Specifically, if the thermoplastic resin constituting the composite material is crystalline, the first predetermined temperature is above the melting point of the thermoplastic resin, and the second predetermined temperature is below the melting point. If the thermoplastic resin constituting the composite material is amorphous, the first predetermined temperature is above the glass transition temperature of the thermoplastic resin, and the second predetermined temperature is below the glass transition temperature.

[0095] The hot press molding method preferably includes at least the following steps B-1) to B-4). B-1) The process of placing the composite material into the mold (lower mold). B-2) A process (first pressing process) in which the mold is heated and pressurized to a temperature above the melting point of the thermoplastic resin but below the thermal decomposition temperature if the thermoplastic resin is crystalline, or to a temperature above the glass transition temperature of the thermoplastic resin but below the thermal decomposition temperature if the thermoplastic resin is amorphous. B-3) A process (second pressing process) that involves one or more stages, in which the pressure in the final stage is increased to 1.2 times or more and 100 times or less the pressure in the first pressing process. B-4) A step to adjust the mold temperature to below the melting point if the thermoplastic resin is crystalline, or below the glass transition temperature if the thermoplastic resin is amorphous. By performing these steps, the molding of the composite material can be completed.

[0096] 3. Common features of cold press molding and hot press molding methods Steps A-2) and B-3) are steps in which pressure is applied to the composite material to obtain a molded body of the desired shape. There are no particular limitations on the molding pressure at this time, but it is preferable to keep it as low as possible within the range in which the desired molded body shape can be obtained. Specifically, it is preferable that the molding pressure be less than 30 MPa relative to the projected area of ​​the mold cavity, more preferably 20 MPa or less, and even more preferably 10 MPa or less. When the molding pressure is less than 30 MPa, it is preferable because it does not require capital investment or maintenance costs for the press machine. Also, naturally, various steps may be inserted between the above steps during compression molding, for example, vacuum compression molding, in which compression molding is performed under vacuum, may be used.

[0097] [Manufacturing method for fiber-reinforced plastic (battery cover): Angle change] 1. Overview The method for manufacturing the battery box of the present invention is: A battery cover is created by compression molding a sheet-shaped composite material using a mold. The angle between the first wall surface and the groove bottom surface immediately after molding is pθ1. When the angle between the second wall surface and the groove bottom surface immediately after molding is pθ2, It is preferable that at least one of the following conditions is met: pθ1 > θ1, or pθ2 > θ2. Here, pθ1 and pθ2 immediately after molding are angles measured within 1.5 minutes after the completion of molding. On the other hand, the angle θ1 between the first wall and the groove bottom and the angle θ2 between the second wall and the groove bottom are angles measured more than 1 hour after the completion of molding.

[0098] 2. Angle Change In other words, it is preferable that the angle between one wall surface and the bottom of the groove, and the angle between the second wall surface and the bottom of the groove, gradually change angle from immediately after molding, so that the angle becomes smaller. This means that immediately after molding, the thermoplastic resin contained in the fiber-reinforced plastic has not yet cooled completely, and as the fiber-reinforced plastic cools, the first and second build-up sections will tilt towards the groove.

[0099] Furthermore, by providing the thickened portion 501, it is possible to more actively shrink the thermoplastic resin, making it easier for the first and second build-up portions to tilt towards the groove. In other words, by providing the thickened portion 501, it is possible to easily complete the molding so that pθ1 > θ1 or pθ2 > θ2.

[0100] Preferably, pθ1 > θ1+1 degrees or pθ2 > θ2+1 degrees, more preferably pθ1 > θ1+3 degrees or pθ2 > θ2+3 degrees, and even more preferably pθ1 > θ1+5 degrees or pθ2 > θ2+5 degrees.

[0101] Furthermore, it is preferable that pθ1 > θ1+1 degrees and pθ2 > θ2+1 degrees, more preferably pθ1 > θ1+3 degrees and pθ2 > θ2+3 degrees, and even more preferably pθ1 > θ1+5 degrees and pθ2 > θ2+5 degrees.

[0102] 3. Draft angle Figure 6 shows an example of a lower mold used in compression molding, where upper and lower molds are used as the molding die. The lower mold in Figure 6 is shown in an enlarged view of the areas of the first recess 601 for forming the first build-up portion and the second recess for forming the second build-up portion.

[0103] Here, the mold preferably has a first recess 601 for forming a first build-up portion and a second recess 602 for creating a second build-up portion, and the first and second recesses preferably have a draft angle for removing the fiber-reinforced plastic from the mold.

[0104] A draft angle is a slope added to the side of fiber-reinforced plastic to make it easier to remove the plastic from the mold. (1) Makes it easier to take out The draft angle prevents the fiber-reinforced plastic from getting caught in the mold, eliminating the risk of breakage during removal. (2) Extending the lifespan of the molding die By providing an appropriate draft angle, wear and damage to the mold can be reduced, extending the mold's lifespan. (3) Improvement of molding quality The presence of a draft angle makes the surface of fiber-reinforced plastic less susceptible to scratches, thus improving its quality.

[0105] There are no particular limitations on the draft angle, but as shown in Figure 6, draft angles θ3 and θ4 are preferably between 1 degree and 5 degrees, and more preferably between 1 degree and 3 degrees.

[0106] However, the draft angle θ3 is the angle between the first side surface 603 of the first recess 601 and the molded surface 605 of the main body. The draft angle θ4 is the angle between the second side surface 604 of the second recess 602 and the molded surface 605 of the main body. The first side surface 603 and the second side surface 604 are the sides for forming the groove 307. [Examples]

[0107] [Creation of composite materials] [material] 1. Reinforced fiber We prepared the following two types of reinforcing fibers. (1) Fiberglass multi-end roving (Owens Corning: OC Paneluxe® 2400Tex) (2) Fiberglass single-ended roving (Owens Corning: SE2348 roving 2000Tex) 2. Resin Polypropylene resin: Novatec® PP BC03C manufactured by Nippon Polypropylene Co., Ltd. 3. Flame retardant ADEKA Corporation's ADEKA stub (registered trademark) FP2100-JC 4. Sealant Commercially available silicone O-ring, 6mm in diameter

[0108] [Example 1] As a thermoplastic resin, a mixture of polypropylene resin (Novatec PP BC03C from Nippon Polypropylene Co., Ltd.) with 11 parts by mass of a flame retardant (Adekastab FP2100-JC) added was prepared. A unidirectional, continuously moving, permeable support with a suction mechanism at its bottom was installed below the polypropylene resin dispenser. While moving the permeable support at 2 m / min, the polypropylene resin was sprayed from the dispenser onto the permeable support, fixing the polypropylene resin onto the permeable support to prepare a polypropylene resin aggregate.

[0109] A rotary cutter was placed above the breathable support, and the single-ended roving from (2) was cut to a constant length of 20 mm using the rotary cutter. At this time, compressed air was supplied directly below the rotary cutter, and the negative pressure generated by the airflow separated the glass fibers from the roll. The compressed air flow rate was 170 L / min.

[0110] Cut glass fibers were scattered onto a pre-fabricated polypropylene resin aggregate on a breathable support and fixed in place to obtain a glass fiber aggregate.

[0111] By adjusting the supply quantities, a composite composition of polypropylene resin aggregate and glass fiber aggregate was prepared with dimensions of 600 mm in width and 3 m in length. The prepared composite composition was heated in a continuous impregnation apparatus to impregnate the glass fibers with polypropylene resin, and then cooled to obtain composite material 1 with a glass fiber volume ratio of 40% and an average thickness of 5.0 mm.

[0112] The composite material 1 is cold-press molded with the mold temperature set to 100°C to create a battery cover having a flange portion and having a first and second thickened portion, as shown in Figures 1 and 3.

[0113] The various dimensions at this time are as follows: Battery cover dimensions: 210cm x 100cm Height of the first build-up section: 4mm Thickness of the first reinforced section: 5mm Height of the second build-up section: 4mm Thickness of the second reinforced section: 5mm pθ1:91 degrees pθ2: 91 degrees θ1:89 degrees θ2: 89 degrees θ3 (pullout angle): 1 degree θ4 (pullout angle): 1 degree In this case, the angle changes are pθ1-θ1=2 degrees and pθ2-θ2=2 degrees.

[0114] Place the battery cover with the first and second thick sections facing upwards, grip the sealant in the groove, and insert it into the battery cover. In this case, the sealant will not fall out even if the battery cover is turned upside down.

[0115] Furthermore, an aluminum battery tray was prepared. The battery tray and the battery cover were fastened together with bolts, and the aforementioned sealing material was sandwiched between the battery tray and the battery cover to obtain a battery box. [Explanation of symbols]

[0116] 101: Battery cover 102: Battery tray 103: Face-to-face area 104: Bolt 105: Flange section of the battery cover 106: Flange section of the battery tray 107: Sealant 108: Color X: Direction in which the opposing area is formed Y: Normal direction of the opposite vector 201: Battery bottom protective cover 202: Fastening rod 203: Insertion hole 204: Insertion platform 205: Impact-absorbing material 206: Battery 207: Battery cover 208: Battery tray 301:First overlay part 302:Second overlay part 303: Main body 304:First wall 305:Second wall 306: Groove bottom surface 307: Groove θ1: Angle between the first wall surface and the bottom surface of the groove. θ2: Angle between the second wall surface and the bottom surface of the groove. 501:Thick part θ3: Draft angle θ4: Draft angle 601: First recess 602: Second recess 603: First side 604:Second side 605: Molding surface 701: Expansion part 702: Fire 703: Clearance between the battery cover and the battery tray

Claims

1. A battery box in which a battery cover and a battery tray are joined via an opposing region, wherein the battery cover is made of fiber-reinforced plastic containing discontinuous reinforcing fibers and thermoplastic resin, The battery cover has a main body, a first reinforced portion, and a second reinforced portion. The first reinforced portion and the second reinforced portion protrude from the main body portion toward the opposite region, A groove is formed by the first wall surface of the first build-up portion, the second wall surface of the second build-up portion, and the bottom surface of the groove between the first wall surface and the second wall surface. At least one of the angles θ1 between the first wall surface and the groove bottom surface, or the angle θ2 between the second wall surface and the groove bottom surface, is less than 90 degrees. Battery box.

2. The opposing area is formed around the entire circumference of the battery cover. The battery box according to claim 1, wherein the groove is formed continuously around the entire circumference of the battery cover.

3. A battery box according to claim 1 or 2, wherein a sealing material is placed in the groove and the sealing material is held by the first build-up portion and the second build-up portion.

4. When the battery tray and the battery cover are joined together, the sealing material is sandwiched between the battery tray and the battery cover. A battery box according to any one of claims 1 to 3.

5. The battery box according to any one of claims 1 to 4, wherein, when the inside of the groove is observed, a thickened portion is formed between the first reinforced portion and the second reinforced portion.

6. The battery cover and the battery tray each have a flange portion, The flange portion of the battery cover and the flange portion of the battery tray are joined together to form the facing region. The battery box according to any one of claims 1 to 5.

7. A battery box according to any one of claims 1 to 6, The angle θ1 and the angle θ2 are less than 90 degrees. Battery box.

8. The battery box according to any one of claims 1 to 7, wherein the weight-average fiber length of the discontinuous reinforcing fiber is 1 mm or more and 100 mm or less.

9. A battery box according to any one of claims 1 to 8, satisfying the following formula (1). Formula (1): t1×E>t1+t2 t1: Thickness of the fiber-reinforced plastic in the opposing region. t2: Clearance between the battery cover and the battery tray in the aforementioned facing area. E: Expansion rate of the fiber-reinforced plastic after 600 seconds of applying a burner flame to the surface of the fiber-reinforced plastic in the aforementioned facing region, such that the flame surface temperature is between 950°C and 1000°C.

10. The battery box according to claim 9, wherein when the battery box is heated, the fiber-reinforced plastic expands toward the facing region.

11. The battery box according to claim 10, wherein when the battery box is heated, the fiber-reinforced plastic expands, thereby sealing the sealing material with the fiber-reinforced plastic.

12. A method for manufacturing a battery box according to any one of claims 1 to 11, The battery cover is created by compression molding a plate-shaped composite material using a mold. The angle between the first wall surface and the groove bottom surface immediately after molding is pθ1. When the angle between the second wall surface and the groove bottom surface immediately after molding is denoted as pθ2, A method for manufacturing a battery box that satisfies at least one of the following conditions: pθ1 > θ1 or pθ2 > θ2.

13. A method for manufacturing a battery box according to claim 12, A method for manufacturing a battery box, wherein the mold has a first recess for forming the first build-up portion and a second recess for creating the second build-up portion, and the first recess and the second recess have a draft angle.

Images