Compact and producing method thereof, as well as battery undercover using the compact

Abstract

To provide a compact that is easy to mold a compact, difficult to pass heat generated from an engine, has fire retardancy, fire resistance, and heat resistance capable of enduring flame or heat due to vehicle fire, and has adiabatic property not allowing heat to pass to a surface opposite a surface facing direct fire and a producing method thereof, as well as a battery undercover formed with the compact.SOLUTION: A compact comprises a shell composed of a fiber reinforced resin and a foam layer formed inside the shell body, wherein the shell is a prepreg cured product in which an inorganic fiber fabric is arranged between the layers of a thermosetting resin film containing an endothermic filler and laminated and integrated, and the foam layer is an expanded material of a foam of thermal expansion particles, and a producing method of the compact, as well as a battery undercover using the compact.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a molded article having a shell-shaped body made of fiber-reinforced resin and a foam layer formed inside the shell-shaped body, a manufacturing method thereof, and a battery undercover using the molded article. [Background technology]

[0002] In recent years, in the fields of automobiles, aircraft, railway cars, etc., molded articles that combine high-strength materials such as fiber-reinforced resins with lightweight core materials such as resin foams have been used as an alternative to metals, which are inferior in terms of light weight. However, acrylic foams and styrene foams, which are widely used as foamed resins, have low heat distortion temperatures, and molded articles that use these foams as core materials are prone to deformation when exposed to high temperatures and have problems with heat resistance, so there is a demand for products with excellent heat resistance (see Patent Document 1).

[0003] In particular, the engine compartment of an automobile, which is prone to high temperatures, contains parts that deteriorate due to heat, and among these, automobile batteries can have their surface heated by the heat from the engine, which is a high-temperature heat source, causing the battery fluid inside to become hot.As a result, there is a risk that the battery's lifespan will be shortened, and there is a demand for covering the battery with a molded body that has excellent thermal insulation properties (see Patent Document 2).

[0004] In addition, vehicle fires caused by lithium-ion batteries have become a problem for electric vehicles (EVs), whose market has expanded rapidly in recent years. Conventional vehicle batteries use inorganic and non-flammable electrolytes, whereas lithium-ion batteries for electric vehicles use flammable organic solvents. This makes it difficult to extinguish the fire once it heats up and catches fire, and in the worst case scenario, it could lead to a major fire. In addition, electric vehicle batteries are often placed under the floor of the vehicle (under the seats), which makes it difficult to extinguish the fire once it catches fire, as they are in a position where water for extinguishing the fire is difficult to reach. For this reason, there is a demand for a battery cover that is flame-retardant and fire-resistant so that the battery will not ignite, at least for the time that people inside the vehicle can escape, even if a vehicle fire occurs. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2018-053079 [Patent Document 2] Republished 2019-098231 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent documents 1 and 2 aim to deal with high temperatures during normal use in automobiles, etc., and Patent document 2 only shows the insulation properties when placed next to a heat source heater heated to 95°C. Therefore, the flame retardancy, fire resistance, and heat resistance of the molded body at extremely high temperatures (approximately 1,000°C) during a fire, as well as the insulation properties of the foam, are unknown. Furthermore, these molded articles are produced by a method in which a thermosetting resin layer is attached to a foamed article after foaming, and therefore the process for obtaining a finished product is complicated.

[0007] The present invention has been made in consideration of the above-mentioned problems, and has an objective of providing a molded body that is easy to mold, is resistant to the passage of heat generated by the engine, has flame retardancy, fire resistance, and heat resistance capable of withstanding flames and heat caused by vehicle fires, etc., and has heat insulating properties that do not allow heat to pass through on the surface opposite to the surface directly exposed to flames, as well as a method for manufacturing the same, and a battery undercover made using the molded body. [Means for solving the problem]

[0008] As a result of extensive research into solving the above-mentioned problems, the inventors discovered that all of the problems of the present invention can be solved by forming a foamed layer of thermally expandable particles inside a shell-shaped body made of flame-retardant fiber-reinforced resin, and thus arrived at the present invention.

[0009] That is, the present invention provides a molded body comprising a shell-shaped body made of fiber-reinforced resin and a foam layer formed inside the shell-shaped body, the shell-shaped body being a cured product of a prepreg in which an inorganic fiber fabric is arranged between layers of a thermosetting resin film containing a heat-absorbing filler and the layers are laminated together, and the foam layer is a foam of thermally expandable particles, as well as a battery undercover for an electric vehicle made using the molded body.

[0010] The present invention also provides a method for producing the molded body, comprising the steps of: placing an inorganic fiber fabric between layers of a thermosetting resin film containing a heat-absorbing filler, and heating and pressurizing the inorganic fiber fabric to impregnate the inorganic fiber fabric with a thermosetting resin and integrate the layers into a prepreg; and placing a foamable sheet having heat-expandable particles supported on a carrier between the layers of the prepreg, and foaming the heat-expandable particles in a molding die to produce the molded body. Effect of the Invention

[0011] According to the molded article of the present invention, it is possible to provide a molded article which is easy to mold, has flame retardancy (non-flammability) and fire resistance so that it will not burn even if it is directly exposed to flames as at a fire scene, and heat resistance so that it will not melt even when exposed to the heat of a flame, and also has heat insulation properties so that it does not pass heat to the surface opposite to the surface that comes into contact with the flame, as well as a battery undercover for an electric vehicle which uses the molded article. In particular, with regard to flame retardancy and fire resistance, the material has flame retardancy (non-flammability) and fire resistance equivalent to passing the fire resistance evaluation test stipulated in Annex 8E of the UN standard Regulation No. 100, making it possible to provide molded products that can withstand flames and heat in the event of a fire.

[0012] According to the method for producing a molded article of the present invention, the heat-expanding particles start to expand by heating the molding die to form a foamed layer, so that a molded article containing a foamed layer (thermal insulating layer) can be produced at once. Therefore, the molded article can be produced in fewer steps while improving the adhesion between the foamed layer and the shell-shaped body. In addition, a molded article with a highly flexible shape that fits the die can be produced. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view illustrating an outline of a molded article of the present invention. [Diagram 2] 1A to 1C are diagrams illustrating a method for producing a molded article according to the present invention. [Diagram 3] FIG. 1 is a diagram illustrating a fire resistance test method. [Figure 4] FIG. 13 is a diagram showing the relationship between flame contact time and back surface temperature in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] As shown in FIG. 1, a molded article 10 of the present invention is composed of a shell-shaped body 2 and a foamed layer 1 formed inside the shell-shaped body 2.

[0015] <Foam layer> The foamed layer 1 in the present invention is formed by foaming a foamable sheet, in which thermally expandable particles are supported on a carrier via an adhesive, in a molding die by heating the foamed sheet in the die. In the present invention, the foam layer contributes to heat insulation.

[0016] The density of the foam layer is 0.06g / cm 3 It is preferable that the density is 0.06 g / cm or less. In other words, it is preferable that the proportion of air is high. 3 If the density is less than 0.05 g / cm, sufficient heat insulation can be achieved, making it difficult for heat to be transmitted to the surface opposite to the surface in contact with fire (hereinafter referred to as the "reverse side"). 3 More preferably, 0.04 g / cm 3 The following is the result.

[0017] Reference symbol (i) in FIG. 1 indicates the thickness of the foamed layer after foaming. The thickness (i) of the entire foam layer is preferably 2 mm to 20 mm. The thickness of the foam layer can be adjusted by the molding temperature and molding pressure of the molded product, and can also be adjusted by increasing the number of laminated foamable sheets described below. If the thickness (i) is within the above range, sufficient heat insulating performance can be exhibited. It is more preferably 2 mm to 15 mm, and even more preferably 2 mm to 10 mm. If the heat insulating performance is sufficient, it is desirable that the thickness (i) of the foam layer is small (i.e., thin).

[0018] <Thermal expansion particles> The thermally expandable particles are preferably so-called microspheres in which a foaming agent (expansion agent) is enclosed in a shell made of a thermoplastic resin. The microspheres have the property that the thermoplastic resin shell softens when heated, and the softened shell expands under the pressure at which the foaming agent inside changes into gas. Examples of the foaming agent include low-boiling aliphatic hydrocarbons.

[0019] The expansion ratio of the thermally expandable particles is preferably 3 to 9 times. The expansion ratio can be adjusted by the molding temperature and molding pressure. The higher the molding temperature, the higher the expansion ratio, and the lower the molding pressure, the higher the expansion ratio. If the expansion ratio is too high, the cell structure during expansion tends to be open cells, making it difficult to form closed cells. If the expansion ratio is within the above range, the particles have sufficient expansion power to form a foamed layer. It is more preferably 3 to 7 times, and even more preferably 4 to 6 times. The structure of the thermally expandable particles after foaming may be either closed cell or open cell. A closed cell structure is preferred because it is difficult for the air in the foam layer to escape to the outside and it easily returns to its original shape, has a repulsive force, and so on.

[0020] The thermally expandable particles preferably have an average particle size of 5 μm to 40 μm before expansion. If the average particle size is less than 5 μm, bubbles of sufficient size may not be formed, and if the average particle size is more than 40 μm, the bubbles may be distributed too densely in the foam layer, and sufficient heat insulating performance may not be exhibited. The average particle size is more preferably 5 μm to 30 μm, and even more preferably 5 μm to 20 μm.

[0021] The microspheres used are commercially available. Specifically, the following can be mentioned: Advancell EM series manufactured by Sekisui Chemical Co., Ltd.; Expancell DU series and WU series manufactured by AkzoNovel; Matsumoto Microsphere F series and FN series manufactured by Matsumoto Yushi Seiyaku Co., Ltd.; and Kureha Microsphere H series manufactured by Kureha Corporation. Among these, low-temperature expansion type microspheres having an expansion start temperature of 70°C to 120°C are preferred. Furthermore, it is preferred that the expansion start temperature is lower than the reaction start temperature of the thermosetting resin described below. By lowering the expansion start temperature to a temperature lower than the reaction start temperature of the thermosetting resin, the thermosetting resin starts to react after the thermoexpandable particles expand, and a molded body can be produced without interfering with the foaming of the foamed layer, so that a molded body of a desired shape can be easily obtained. The temperature is more preferably 80°C to 120°C, and even more preferably 90°C to 110°C.

[0022] The thermally expandable particles are preferably supported on a carrier when used, which allows them to be easily laminated in a desired shape. Examples of carriers for carrying the thermally expandable particles include nonwoven fabrics, cloths, sheets, paper, resin films, etc. Among these, nonwoven fabrics are preferred because they allow the thermally expandable particles to be attached uniformly, they require a small storage area, they are less likely to affect the foamed layer or shell-shaped body even when exposed to heat during molding, and they have a small basis weight.

[0023] Examples of fibers that can be used as nonwoven fabrics include synthetic fibers such as polyester fibers, polycarbonate fibers, polyacrylonitrile fibers, oxidized polyacrylonitrile fibers, vinylon fibers, olefin fibers, polyurethane fibers, aramid fibers, acrylic fibers, polylactic acid fibers, polyvinyl chloride fibers, vinylidene fibers, polyphenylene sulfide fibers, polyetherimide fibers, polyethersulfone fibers, polyetherimide fibers, and polyetheretherketone fibers; inorganic fibers such as carbon fibers, glass fibers, and ceramic fibers; natural fibers such as cotton, hemp, wool, and silk; and regenerated fibers such as rayon, cupra, and lyocell. These fibers may be used alone or in combination of two or more. Among these, polyester fibers are preferred in terms of cost, ease of handling, heat resistance, and the like. The weight of the nonwoven fabric is 10g / m 2 ~30g / m 2 This allows the carrier to support sufficient thermo-expandable particles for forming a foamed layer, and also reduces the influence of the properties of the carrier itself (density, thermal conductivity, etc.). More preferably, it is 10 g / m 2 ~20g / m 2 , and more preferably 10 g / m 2 ~15g / m 2 It is.

[0024] <Adhesive> The adhesive is not particularly limited, and known adhesives can be used. The adhesive may be selected based on the excellent retention of thermally expandable particles. Specific examples of the adhesive include acrylic resin adhesives, vinyl copolymer resin adhesives, ethylene vinyl acetate copolymer adhesives, urethane resin adhesives, epoxy resin adhesives, chloroprene rubber adhesives, nitrile rubber adhesives, styrene-butadiene rubber adhesives, and natural rubber adhesives.

[0025] <Foamable sheet> In the present invention, the expandable sheet (reference numeral 11 in FIG. 2) refers to a sheet-like material before expansion (unexpanded state) in which the thermally expandable particles are supported on a carrier (nonwoven fabric or the like) via an adhesive. The shape is preferably a sheet from the viewpoints of ease of setting (fixing) in a mold during molding and reduction in storage area, but may be a film. The foamable sheet may be used alone or in a laminate of multiple sheets. The upper limit of the number of sheets to be laminated is not particularly limited as long as the thickness after foaming does not exceed the above-mentioned thickness (i) of the entire foam layer.

[0026] As a method for supporting the thermally expandable particles on the carrier, known methods can be used, such as a method in which the thermally expandable particles and the adhesive are mixed in water, the aqueous dispersion is stirred and dispersed, and the aqueous dispersion is applied to the carrier by a roller, a spray, a brush, or the like, and then dried, or a method in which the carrier is immersed (dipped) in a bathtub containing the aqueous dispersion and then dried. Among these, dipping is preferred because it is easy to attach the particles uniformly to the carrier and is easy to work with. The drying method is not particularly limited, and may be any method such as natural drying, air drying, drying with a dryer, etc.

[0027] The basis weight of the foam sheet is 50g / m 2 ~250g / m 2 Within the above range, a foamed layer can be formed with a sufficient thickness, and there is no risk of impairing the heat insulating properties. The foamable sheet can increase the thickness of the foamed layer after foaming by increasing the basis weight. More preferably, it is 100 g / m 2 ~200g / m 2 , and more preferably 120 g / m 2 ~180g / m 2 It is.

[0028] The thickness of the expandable sheet before expansion is preferably 0.1 mm to 1.0 mm. If it is within the above range, it is possible to obtain a sheet that supports a sufficient amount of thermally expandable particles as a foamed layer, and since it is not bulky, it is easy to store. It is more preferably 0.2 mm to 0.7 mm, and further preferably 0.2 mm to 0.4 mm.

[0029] <Shell-like body> The shell-shaped body of the present invention (reference numeral 2 in FIG. 1 ) is made by preparing a film from a resin composition containing a thermosetting resin, a heat-absorbing filler, etc., and then arranging an inorganic fiber fabric between the layers of the obtained resin film to laminate them together to obtain a prepreg, which is then reacted and cured by heating in a molding machine. In the present invention, the shell-shaped bodies contribute to flame retardancy, fire resistance, and heat resistance.

[0030] <Thermosetting resin> In the present invention, a thermosetting resin is used as the resin constituting the fiber-reinforced resin layer because a resin with a high heat distortion temperature and melting point is suitable. Since the present invention aims to provide flame retardancy, fire resistance, and heat resistance that can withstand even exposure to flames exceeding 1,000°C, a thermoplastic resin is insufficient. Examples of the thermosetting resin include epoxy resin, phenol resin, unsaturated polyester resin, vinyl ester resin, maleimide resin, bismaleimide resin, cyanate resin, benzoxazine resin, urea resin, melamine resin, benzocyclobutene, and the like, as well as copolymers and modified products thereof. These resins may be used alone or in combination of two or more. Among these, epoxy resin, unsaturated polyester resin, and benzoxazine resin are preferred from the viewpoints of adhesion to inorganic fiber fabrics and ease of handling.

[0031] The epoxy resin used in the present invention is not particularly limited as long as it is a curable epoxy compound having two or more epoxy groups in one molecule. The epoxy resin may be solid at room temperature, liquid at room temperature, or liquid at room temperature after being diluted with a reactive diluent, and two or more of these may be used in combination. When an epoxy resin that is solid at room temperature and an epoxy resin that is liquid at room temperature are used in combination, the amount of liquid epoxy resin to be blended with respect to the total amount of thermosetting resin is preferably 10% to 45%. By blending within the above range, a resin varnish with good handleability can be obtained even when a large amount of heat absorbing filler is blended. More preferably, it is 10% to 35%, even more preferably 10% to 30%, and particularly preferably 10% to 25%.

[0032] As the epoxy resin that is solid at room temperature, a polyfunctional epoxy resin having a plurality of glycidyl groups is preferred. For example, bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, and bisphenol S type epoxy resin; novolac type epoxy resins such as phenol novolac type epoxy resin and cresol novolac type epoxy resin; glycidylamine type epoxy resin; epoxy resin having a naphthalene skeleton; epoxy resin having a dicyclopentadiene skeleton; alicyclic epoxy resin, etc. may be used alone or in combination of two or more. Among these, bisphenol A type epoxy resin is preferred from the viewpoint of mechanical strength properties.

[0033] The liquid epoxy resin that can be used in the present invention is an epoxy resin having a viscosity of about 5,000 cp or less at room temperature (25° C.). Among liquid epoxy resins, bisphenol A type liquid epoxy resin is preferred because of its excellent heat resistance. When a liquid epoxy resin is blended with a large amount of a heat absorbing filler described later, it gives the desired viscosity and sufficient fluidity (handling property) to enable coating on a process paper. In addition, in order to impart tackiness to a resin film or prepreg, adhesion at room temperature is necessary, and while a large amount of epoxy resin is preferable for improving adhesion and toughness, it is preferable to use as little as possible in order to reduce smoke generation from the cured composition and not impair heat resistance and flame retardancy. When used in combination with an epoxy resin that is solid at room temperature, the solid epoxy resin is dissolved in a solvent before being introduced, which makes it easy to impart the desired viscosity and fluidity.

[0034] A solvent or a reactive diluent can be used to dissolve and dilute the thermosetting resin. The solvent is not particularly limited. Specific examples of the solvent include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol butyl ether acetate, methyl lactate, ethyl lactate, and butyl lactate; alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol; aliphatic hydrocarbons such as octane and decane; and petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha.

[0035] As the reactive diluent, a monofunctional or polyfunctional epoxy-based reactive diluent can be used. As the epoxy-based reactive diluent, one or a mixture of two or more selected from a monofunctional diluent, a bifunctional diluent, and a trifunctional diluent can be used. Specific examples of the reactive diluent include the following. Examples of monofunctional diluents include n-butyl glycidyl ether, pt-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, C8-C10 alkyl glycidyl ether, C12-C14 alkyl glycidyl ether, pt-butylphenyl glycidyl ether, nonylphenyl glycidyl ether, phenyl glycidyl ether, o-cresyl glycidyl ether, and dicyclopentadiene diepoxide. Examples of bifunctional diluents include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, and cyclohexanedimethanol diglycidyl ether. Examples of trifunctional diluents include trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, and triglycidyl paraaminophenol.

[0036] <Heat absorbing filler> Examples of the endothermic filler in the present invention include aluminum hydroxide and magnesium hydroxide. One type may be used alone, or two or more types may be used in combination. Among them, aluminum hydroxide is particularly preferred. The endothermic filler generates water when heated, so that it can delay the temperature rise of the shell-shaped body when the molded body is exposed to a flame, and contributes to flame retardancy (non-combustibility) and heat resistance. In addition, since it is not an organic substance, it does not generate toxic gases even when exposed to a flame, and can suppress human damage. The content of the endothermic filler is preferably in the range of 1.1 to 3.0 times by weight relative to the total amount of the thermosetting resin. If it is less than 1.1 times the total amount of the thermosetting resin, it becomes difficult to impart non-flammability to the cured product, and if it exceeds 3.0 times the total amount of the thermosetting resin, it becomes difficult to disperse the endothermic filler in the composition. It is more preferably 1.2 to 2.5 times by weight, even more preferably 1.4 to 2.0 times by weight, and particularly preferably 1.6 to 1.9 times by weight.

[0037] Furthermore, in addition to the above-mentioned components, the thermosetting resin composition of the present invention may contain a curing agent, a curing accelerator, a thermoplastic resin, an elastomer, a flame retardant, an ultraviolet absorber, an antioxidant, an adhesion improver, a silane coupling agent, etc., within the scope of not impairing the effects of the present invention. The above-mentioned additives may be used alone or in combination of two or more kinds. Examples of the curing agent include amine-based curing agents such as dicyandiamide, aromatic polyamines, aliphatic amines, aminobenzoic acid esters, thiourea-added amines, and hydrazides; phenol-based curing agents such as bisphenol, phenol novolac resins, cresol novolac resins, and polyphenol compounds; acid anhydride-based curing agents such as phthalic anhydride, maleic anhydride, succinic anhydride, and carboxylic acid anhydrides; mercaptan-based curing agents such as polymercaptan and polysulfide resins; etc. These may be used alone or in combination of two or more. As the curing accelerator, curing accelerators for epoxy resins such as imidazoles and their derivatives, organic phosphorus compounds, secondary amines, tertiary amines, and quaternary ammonium salts can be used, and one type can be used alone or two or more types can be used in combination. These additives are preferably mixed in an amount of 0 to 5 parts by weight based on 100 parts by weight of the thermosetting resin.

[0038] <Resin film> The resin film of the present invention can be obtained by applying a thermosetting resin composition, which is prepared by mixing and dispersing a heat absorbing filler, a thermosetting resin, and other additives, onto a release paper, drying the composition, and peeling off the release paper after drying. The method of coating the release paper is not particularly limited, and any known method can be used. Specifically, roll coating, spray coating, dipping, brush coating, trowel coating, etc. are included. Among these, roll coating and spray coating are preferred because they are easy to control the film thickness and can be applied uniformly. The drying method is not particularly limited, and may be any method such as natural drying, air drying, drying with a dryer, etc.

[0039] <Prepreg> The prepreg of the present invention is obtained by sandwiching an inorganic fiber fabric between layers of the resin film obtained above and pressing the fabric to impregnate the inorganic fiber fabric with a thermosetting resin. The weight of the prepreg is 500g / m 2 ~1,000g / m 2Within the above range, there is no problem with resin impregnation, winding onto a roll during production, and handling during molding. More preferably, it is 600 g / m 2 ~1,000g / m 2 , and more preferably 700 g / m 2 ~900g / m 2 It is.

[0040] The inorganic fiber fabric is preferably flame retardant (particularly non-flammable), and specific examples thereof include carbon fiber, glass fiber, metal fiber, and the like. Among these, carbon fiber and glass fiber are preferred in terms of cost and ease of processing. The carbon fiber can be appropriately selected from polyacrylonitrile-based, rayon-based, and pitch-based fibers. These fibers may be used alone or in combination of two or more types.

[0041] The shape of the inorganic fiber fabric is preferably one selected from the group consisting of woven fabric, knitted fabric, and nonwoven fabric, of which woven fabric is more preferred for the reason of flame resistance. Examples of the woven fabric include a so-called tow sheet in which non-flammable fibers are arranged in one direction, a bidirectional woven fabric, a multiaxial woven fabric such as a triaxial woven fabric, and the like. Examples of knitted fabrics include those knitted by a weft knitting machine such as a circular knitting machine, and a warp knitting machine such as a tricot knitting machine, a raschel knitting machine, or a Milanese knitting machine.

[0042] The weight of inorganic fiber fabric is 50g / m 2 ~500g / m 2 If the basis weight is too large, it becomes difficult to impregnate the thermosetting resin in a short time. On the other hand, if the basis weight is too small, the mechanical properties of the fiber-reinforced resin layer may be insufficient. More preferably, it is 50 g / m 2 ~450g / m 2 , and more preferably 75 g / m 2 ~400g / m 2 There is no limit to the number of inorganic fiber fabrics used, but from the perspective of weight reduction, four or less is preferable.

[0043] <Method of manufacturing molded body> The molded article of the present invention can be obtained by a step of producing a prepreg from a resin film made of a thermosetting resin composition and an inorganic fiber fabric, and a step of producing a molded article from the prepreg and a foamable sheet.

[0044] (1) Prepreg manufacturing process This process is a process in which a film is produced from a resin composition containing a heat absorbing filler, a thermosetting resin, and other additives, and the resulting resin film and an inorganic fiber fabric are laminated to produce a thermosetting resin prepreg. The method of laminating the resin film and the inorganic fiber fabric is not particularly limited as long as both sides of the fiber fabric are sandwiched between the resin films. Specifically, a method of laminating one or more resin films on each side of the fabric, or a method of laminating two or more fabrics with three or more resin films alternately can be mentioned. Increasing the number of layers can increase the strength of the shell-shaped body. On the other hand, it may become difficult to adjust the thickness of the foamed layer.

[0045] (2) Manufacturing process of molded body In this step, an unfoamed foamable sheet is laminated between the layers of the prepreg produced in the previous step, fixed to a molding machine, and the molding die is heated to foam the heat-expanding particles in the molding machine and harden the thermosetting resin to produce a molded body. At this time, it is essential that the hardening temperature of the thermosetting resin is higher than the reaction temperature of the heat-expanding particles. As shown in FIG. 2(b), when fixed to the molding machine, the foamable sheet 11 is arranged so that the entire sheet is placed on the prepreg 12. During molding, the ends of the prepreg are bonded to seal the foamable sheet.

[0046] According to the method for producing a molded product of the present invention, a molded product that conforms to the shape of a mold can be obtained, and thus the degree of freedom in shape is high, compared with a conventional molded product in which a fiber-reinforced resin or the like is attached to a foamed body. In addition, since a molded product containing a foamed layer can be obtained at once, the adhesion between the foamed layer and the fiber-reinforced resin that constitutes the shell-shaped body is good, and there is no need to bother with bonding between the layers.

[0047] The lamination method is not particularly limited as long as both sides of the foamable sheet are sandwiched between prepregs. Specifically, there are a three-layer structure in which one prepreg is laminated on each side of the foamable sheet, a modified five-layer structure in which two prepregs are laminated on each side of the foamable sheet (FIG. 2(a)), a modified four-layer structure in which two prepregs are laminated on one side of the foamable sheet and one prepreg on the other side, and a five-layer structure or more in which two or more foamable sheets are alternately laminated with three or more prepregs (multilayer structure). In addition, the modified five-layer structure and modified four-layer structure may have three or more prepregs on one side.

[0048] As a molding method in the process for producing the molded article of the present invention, a pressure / vacuum molding method such as press molding, vacuum bag molding, autoclave molding, or normal pressure molding method can be adopted. The pressure during pressure / vacuum molding is preferably in the range of 0 MPa to 0.3 MPa. The expansion ratio of the foamed layer can be adjusted by adjusting the pressure, and the lower the pressure, the higher the expansion ratio of the foamed layer. The pressure is more preferably 0 MPa to 0.2 MPa, and even more preferably 0 MPa to 0.1 MPa. The temperature of the molding die during molding is not particularly limited as long as it is a temperature at which the thermosetting resin and the thermally expandable particles used react. Specifically, it is preferably 100°C to 160°C. If it is within the above range, it becomes easy to adjust the expansion ratio of the thermally expandable particles. It is more preferably 120°C to 150°C, and even more preferably 130°C to 140°C.

[0049] According to the present invention, it is possible to obtain a molded body that has fire resistance, heat resistance, and flame retardancy equivalent to passing the evaluation test (at about 1,000°C level) specified in Annex 8E of the UN standard Regulation No. 100 (Uniform provisions concerning the approval of vehicles with regard to specific requirements for the electric power train), and that also has excellent thermal insulation properties. For the evaluation of heat insulation, it is preferable that the temperature of the back side of the test specimen is less than 250°C in a test equivalent to the above-mentioned standard. If it is less than 250°C, there are advantages such as suppressing the shortening of the battery life caused by heat from the engine, etc., and suppressing heat generation and ignition of electric vehicle batteries. It is more preferable that it is less than 230°C, and even more preferable that it is less than 200°C.

[0050] Reference symbol (ii) in FIG. 1 indicates the thickness of the molded article of the present invention. The thickness of the molded article is preferably 1 mm to 25 mm. If it is within this range, it is possible to provide a battery cover that can withstand flames and heat in the event of a fire. It is more preferably 2 mm to 20 mm, and further preferably 3 mm to 18 mm.

[0051] In the molded article of the present invention, the fiber-reinforced resin layer (shell-shaped body) has flame retardancy (non-flammability), heat resistance, and fire resistance, so that even if the molded article comes into contact with a flame due to a fire or the like, the flame will not penetrate the fiber-reinforced resin layer. In addition, since the foam layer has heat insulating properties, it not only does not transmit heat generated from an engine or the like, but also exhibits heat insulating properties that make it difficult for heat to be transmitted to the back side even if the molded article comes into contact with a flame. Therefore, the molded article can be suitably used as a battery cover for an automobile, particularly as a battery undercover for an electric automobile. EXAMPLES

[0052] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0053] [Materials used] (1) Thermosetting resin composition (a-1) Thermosetting resin 1: Epoxy resin (E-001-75MEK (containing 25% methyl ethyl ketone), manufactured by Ohtake Meishin Chemical Co., Ltd.) (a-2) Thermosetting resin 2: Liquid epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation) (b) Hardener: Dicyandiamide (DDA 5, Huntsman) (c-1) Curing accelerator: Imidazole-based curing accelerator (Curesol 2P4MHZ, manufactured by Shikoku Chemical Industries, Ltd.) (c-2) Curing accelerator: Imidazole-based curing accelerator (Curesol 2PHZ-PW, manufactured by Shikoku Chemical Industries, Ltd.) (c-3) Curing accelerator: Imidazole-based curing accelerator (Curesol 2MZ-A, manufactured by Shikoku Chemical Industries, Ltd.) (d) Endothermic filler: Aluminum hydroxide (CWL-325J, manufactured by Sumitomo Chemical Co., Ltd.) (e) Solvent: Methyl ethyl ketone

[0054] (2) Glass fiber cloth (ERW 320-554A / T, basis weight 320g / m 2 (manufactured by Central Fiber)

[0055] (3) Foaming agent composition (f) Foaming agent: thermally expandable microspheres (Matsumoto Microsphere FN-77, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) (g) Adhesive: Vinyl copolymer resin adhesive (CVC700, manufactured by Konishi Co., Ltd.) (h) Diluent: Water

[0056] (4) Carrier: Polyethylene terephthalate nonwoven fabric (Eltas E01012, basis weight 12 g / m 2 (manufactured by Asahi Kasei Corporation)

[0057] Table 1 shows the amounts of each composition (raw material) used in Examples 1 to 3 and Comparative Examples 1 to 3.

[0058] [Table 1]

[0059] Example 1 After dissolving the epoxy resin (a-1) in a solvent (methyl ethyl ketone (e)), the liquid epoxy resin (a-2) is introduced into the epoxy resin solution and mixed in. The curing agent (b), the curing accelerator (c-1), and aluminum hydroxide (d) are added thereto and stirred and dispersed to prepare a thermosetting resin composition.

[0060] (A) Preparation of resin film The composition was applied to a release paper using a bar coder, introduced into a dryer, and dried to remove the solvent, thereby producing a resin film. The basis weight of the obtained resin film was about 235 g / m 2 The gel time of the resin film at 130°C was 15 minutes.

[0061] (a) Preparation of prepreg The glass fiber cloth was sandwiched between the resin films on both sides and pressed in a mold heated to 80°C for 2 minutes (pressure 0.2 MPa) to impregnate the glass fiber cloth with the resin to obtain a prepreg. The basis weight of the obtained prepreg was about 850 g / m 2 It was.

[0062] (c) Preparation of foam sheet The foaming agent (f), adhesive (g) and diluent (h) were placed in a bath and stirred and dispersed, and then a polyethylene terephthalate nonwoven fabric was immersed in the bath to adhere the foaming agent composition. The fabric was then introduced into a dryer and dried to produce a foamable sheet. The basis weight of the foamable sheet obtained after drying was about 140 g / m 2 The basis weight (calculated value) of the foaming agent in the foamable sheet was about 96 g / m 2 The foaming start temperature of the foamable sheet was about 100°C.

[0063] (D) Lamination method of molded bodies Two prepregs (12) were laminated on each side of the foamable sheet (11) in the order and number shown in Fig. 2(a), and the laminate was set in a vacuum bag molding die. The prepreg 12 had a weight of 194 g and a basis weight of 3079 g / m 2 The foamable sheet 11 had a weight of 7.5 g and a basis weight of 137 g / m 2 The number of ply in Table 3 indicates the number of layers of the prepreg 12.

[0064] (E) Method for forming molded body After being fixed to the mold, the temperature was raised from room temperature to 140°C over approximately 1 hour while reducing the pressure to 0.1 MPa, and then the temperature was held for another hour before being allowed to cool. Burrs generated during molding were removed to produce a molded body 10 (test plate).

[0065] (F) Fire resistance test As shown in Fig. 3, the prepared test plate 10 was fixed horizontally, and a Bunsen burner 13 was placed so that the tip of the flame was 5 cm away from the test plate 10. The burner was ignited, and the test plate 10 was evaluated after being exposed to the flame for 130 seconds with the tip of the flame in contact with the test plate 10. The evaluation items were confirmation (visual inspection) of the presence or absence of through holes (holes) due to exposure to flame, and continuous measurement of the temperature of the back side during exposure to flame. The back side temperature was measured using an infrared radiation thermometer (CS-40TAC-HT, manufactured by Optex FA Co., Ltd.).

[0066] (Examples 2 to 3) Test plates were prepared in the same manner as in Example 1, except that the molding thickness of the molded bodies (test plates) was changed, and a fire resistance test was carried out in the same manner as in Example 1.

[0067] (Comparative Examples 1 to 3) (D) Test panels were prepared in the same manner as in Example 1, except that no foaming sheet was used and the number of laminated prepregs was changed, and a fire resistance test was carried out in the same manner as in Example 1.

[0068] Table 2 shows the amounts of each composition (raw material) used in Examples 4-9 and Comparative Examples 4-6.

[0069] [Table 2]

[0070] Example 4 (A) A resin film was produced in the same manner as in Example 1. The basis weight of the resin film was about 245 g / m 2 The gel time at 130°C was 15 minutes. (a) Using the obtained resin film, a prepreg was produced in the same manner as in Example 1. The weight of the obtained prepreg was about 810 g / m 2 It was. (c) A foamable sheet was produced in the same manner as in Example 1. The basis weight of the obtained foamable sheet was about 150 g / m 2 The calculated basis weight of the foaming agent in the foamable sheet was about 95 g / m 2 The foaming start temperature of the foamable sheet was about 100°C. (d) The foamable sheet and the prepreg were laminated and fixed to the mold in the same manner as in Example 1. The prepreg had a weight of 143 g and a basis weight of 3240 g / m 2 The foam sheet was cut to a size of 22 cm wide x 20 cm long and had a weight of 2.16 g and a basis weight of 150 g / m 2 The size of the sample was 12cm wide x 12cm long. (E) A molded body (test plate) was produced in the same manner as in Example 1 (vacuum bag), except that the pressure during molding was reduced to 0.06 MPa. (f) The obtained test panels were subjected to a fire resistance test in the same manner as in Example 1.

[0071] Example 5 Test plates were prepared in the same manner as in Example 4, except that (a) the curing accelerator in the resin composition was changed to c-2, and (e) the molding temperature during molding was changed to 160°C and the molding pressure was changed to a reduced pressure of 0.1 MPa. Fire resistance tests were conducted in the same manner as in Example 4. The weight of the resin film is approximately 245g / m 2 The gel time at 160°C was 15 minutes.

[0072] (Comparative Examples 4 to 5) Test panels were prepared in the same manner as in Example 4, except that (e) the number of layers of prepregs (number of plies) was changed, and (e) the pressure during molding was reduced by 0.1 MPa. Fire resistance tests were conducted in the same manner as in Example 4.

[0073] Comparative Example 6 Test plates were prepared in the same manner as in Example 4, except that (a) the curing accelerator in the resin composition was changed to c-3, and (e) the molding temperature during molding was changed to 110°C and the molding pressure was changed to a reduced pressure of 0.1 MPa. Fire resistance tests were conducted in the same manner as in Example 4.

[0074] Example 6 (E) Test panels were prepared in the same manner as in Example 4, except that the molding method for the molded bodies was changed, and a fire resistance test was carried out in the same manner as in Example 4. The molding method was as follows: the prepreg and foam sheet were placed on a flat aluminum mold and then placed in a dryer, where the temperature was raised from room temperature to 140°C over approximately one hour, and then held for a further hour before being allowed to cool. Burrs generated during molding were then removed to produce the test plates (normal pressure molding).

[0075] Example 7 A test plate was prepared in the same manner as in Example 6 (normal pressure molding), except that (a) the curing accelerator in the resin composition was changed to c-2, and (e) the molding temperature during molding was changed to 160°C. A fire resistance test was performed in the same manner as in Example 6. The weight of the resin film is approximately 245g / m 2 The gel time at 160°C was 15 minutes.

[0076] Example 8 (E) Test panels were prepared in the same manner as in Example 4, except that the molding method for the molded bodies was changed, and a fire resistance test was carried out in the same manner as in Example 4. The molding method involved placing the laminated prepreg and foaming sheet in a vacuum bag and applying pressure (0.1 MPa) while reducing the pressure (-0.1 MPa). While reducing and applying pressure, the temperature was raised from room temperature to 140°C over about an hour, and then held for another hour before being allowed to cool. Flash generated during molding was removed to produce a test panel (autoclave molding).

[0077] Example 9 (E) Test plates were prepared in the same manner as in Example 8 (autoclave molding) except that the pressure (pressurization) during molding was changed to 0.2 MPa, and a fire resistance test was carried out in the same manner as in Example 8.

[0078] Table 3 shows the test results for the test plates prepared in Examples 1-9 and Comparative Examples 1-6.

[0079] [Table 3]

[0080] From the results of Table 3 and FIG. 4, the molded article of the present invention having a foam layer can suppress the rise in the temperature on the back side compared to the molded article without a foam layer (Examples 1-3, Comparative Examples 1-3). In other words, it is found that the molded article exhibits high thermal insulation performance on the back side even under the ultra-high temperatures assumed in a fire. In addition, since no through holes are observed in the molded article even when it is exposed to fire in a fire, the safety of the back side can be ensured. The same effect is achieved when the molding conditions are changed (Examples 4-5). It is also evident that the molded article of the present invention can maintain the back surface temperature and combustion state at the same level even when the molding method is changed (Examples 6 to 9). [Industrial Applicability]

[0081] The molded article of the present invention has excellent flame retardancy (non-flammability), fire resistance, heat resistance, and heat insulation properties, and can therefore be used for interior materials and parts of railway cars, aircraft, and other vehicles. In particular, it can be suitably used as a battery cover for automobiles, and particularly as a battery undercover for electric automobiles. [Explanation of symbols]

[0082] 1 Foam layer 2. Shell-like body 10 Molded body 11 Foam Sheet 12 Prepreg 13 Burner

Claims

1. The present invention comprises a shell-shaped body made of a fiber-reinforced resin and a foam layer formed inside the shell-shaped body, The shell-shaped body is a cured prepreg obtained by arranging an inorganic fiber fabric between layers of a thermosetting resin film containing a heat absorbing filler and laminating and integrating the layers, The foam layer is a foam of thermally expandable particles. A molded article characterized by:

2. The molded article according to claim 1 , wherein the thermally expandable particles are supported on a carrier.

3. The molded article according to claim 1, wherein the expansion ratio of the thermally expandable particles is 3 to 9 times.

4. The density of the foam layer is 0.06 g / cm ３ The molded body according to claim 1 , wherein:

5. A battery undercover for an electric vehicle, comprising the molded article according to any one of claims 1 to 4.

6. A method for producing the molded body according to any one of claims 1 to 4, a step of disposing an inorganic fiber fabric between layers of a thermosetting resin film containing a heat absorbing filler, and impregnating the inorganic fiber fabric with a thermosetting resin by heating and pressurizing the inorganic fiber fabric to produce a laminated and integrated prepreg; a step of disposing a foamable sheet having thermally expandable particles supported on a carrier between the layers of the prepreg, and expanding the thermally expandable particles in a molding die to produce a molded body; A method for producing a molded article, comprising the steps of:

7. The method for producing a molded article according to claim 6, wherein the molding method in the step of producing the molded article is vacuum bag molding, autoclave molding or atmospheric molding.

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