A crystalline unsaturated polyester resin composition for battery holders, granular material made from the composition, and a battery holder formed by molding the granular material.

Abstract

To provide a crystalline unsaturated polyester resin composition capable of providing a product having excellent thermal conductivity by using a crystalline unsaturated polyester resin as an unsaturated polyester resin.SOLUTION: A crystalline unsaturated polyester resin composition for a battery holder at least includes a crystalline unsaturated polyester resin and an inorganic filler. The crystalline unsaturated polyester resin includes a crystalline unsaturated polyester and a copolymerizable monomer and / or a copolymerizable polymer.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an unsaturated polyester resin composition for a battery holder, a granular material composed of the composition, and a battery holder formed by molding the granular material. In particular, it relates to a resin composition composed of a crystalline unsaturated polyester, a granular material composed of the composition, and a battery holder formed by molding the granular material.

Background Art

[0002] Rechargeable batteries are widely used in electronic devices such as smartphones and notebook computers, as well as in transportation equipment such as electric vehicles and infrastructure such as power storage systems. There are concerns about a large amount of power consumption in a short time, rapid charging, and heat generation due to long-time charging in electric vehicles and power storage systems, and accidents accompanied by fires have occurred. With the occurrence of accidents, safe members are required, and there is a demand for highly reliable holders made of thermosetting resins.

[0003] In a battery, thermal runaway occurs suddenly due to the reaction of the positive electrode and negative electrode with the electrolyte and the thermal decomposition of the positive electrode and negative electrode, leading to rupture and ignition. It is known that thermal runaway of a battery occurs due to the overlap of internal and external short circuits, overcharging, over-discharging, and their combined factors. If the battery can be preheated before thermal runaway occurs, it is possible to prevent accidents.

[0004] Conventionally, there is known a battery holder that is at least composed of a tubular body having a through space for housing a battery inside and having a uniform thickness, the tubular body being formed of a resin composition containing an inorganic filler, the thickness of the tubular body being within the range of 0.5 to 3.0 mm, and the ratio of the maximum width of the through space of the tubular body to the maximum width of the battery being within the range of 60% to 100% (Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] However, as mentioned in Patent Document 1 above, in this field, there is a technical challenge in that the structure of the battery holder is limited, which imposes constraints on the design. Therefore, there is a need for the development of a resin composition that can be applied without depending on the structure of the battery holder.

[0007] Furthermore, as mentioned above, there are concerns about heat generation due to rapid charging and prolonged charging. Moreover, battery thermal runaway occurs due to a combination of factors, including internal and external short circuits, overcharging and over-discharging, and combinations thereof. For this reason, there is a need for a resin composition that can provide products with good heat dissipation properties, i.e., good thermal conductivity, to prevent thermal runaway.

[0008] Therefore, the present invention aims to provide a crystalline unsaturated polyester resin composition that can provide a product having good thermal conductivity by using a crystalline unsaturated polyester resin as the unsaturated polyester resin. [Means for solving the problem]

[0009] The inventors of the present invention have conducted extensive and multifaceted studies on the use of unsaturated polyester resins in resin compositions for battery holders, and as a result have discovered the crystalline unsaturated polyester resin composition of the present invention.

[0010] In other words, the crystalline unsaturated polyester resin composition for battery holders of the present invention is a crystalline unsaturated polyester resin composition comprising at least a crystalline unsaturated polyester resin and an inorganic filler, wherein the crystalline unsaturated polyester resin comprises a crystalline unsaturated polyester and a copolymerizable monomer and / or copolymerizable polymer.

[0011] Furthermore, in a preferred embodiment of the crystalline unsaturated polyester resin composition for battery holders of the present invention, the ash content of the resin composition after heating it at 625°C for 3 hours is 30-75%.

[0012] Furthermore, in a preferred embodiment of the crystalline unsaturated polyester resin composition for battery holders of the present invention, the inorganic filler is characterized in that it is 50 to 80% by mass of the total amount of the resin composition.

[0013] Furthermore, in a preferred embodiment of the crystalline unsaturated polyester resin composition for battery holders of the present invention, the inorganic filler is characterized by containing at least one of aluminum hydroxide, alumina, magnesium hydroxide, and magnesium oxide.

[0014] Furthermore, in a preferred embodiment of the crystalline unsaturated polyester resin composition for battery holders of the present invention, the average particle size of the inorganic filler is in the range of 0.1 to 50 μm.

[0015] Furthermore, the granular material of the present invention is characterized by being composed of the crystalline unsaturated polyester resin composition for battery holders of the present invention.

[0016] Furthermore, the molded article of the present invention is characterized by being formed from granular material made of the crystalline unsaturated polyester resin composition for battery holders of the present invention.

[0017] Furthermore, in a preferred embodiment of the molded article of the present invention, the thermal conductivity of the molded article is characterized by being 0.8 W / m·K or higher.

[0018] Furthermore, in a preferred embodiment of the molded article of the present invention, the flame retardancy based on the UL94 combustion test is V-0 at a thickness of 0.8 mm of the molded article.

[0019] Furthermore, in a preferred embodiment of the molded article of the present invention, the molded article is characterized in that it is a battery holder.

[0020] Further, the battery pack of the present invention is characterized by including the battery holder of the present invention.

Advantages of the Invention

[0021] According to the crystalline unsaturated polyester resin composition for a battery holder of the present invention, there is an advantageous effect of excellent flame retardancy. Further, according to the crystalline unsaturated polyester resin composition for a battery holder of the present invention, there is an advantageous effect of having good thermal conductivity.

Embodiments for Carrying Out the Invention

[0022] The crystalline unsaturated polyester resin composition for a battery holder of the present invention is a crystalline unsaturated polyester resin composition containing at least a crystalline unsaturated polyester resin and an inorganic filler, wherein the crystalline unsaturated polyester resin is composed of a crystalline unsaturated polyester and a copolymerizable monomer and / or a copolymerizable polymer. In the present specification, the crystalline unsaturated polyester resin composition for a battery holder may be simply referred to as a crystalline unsaturated polyester resin composition.

[0023] Further, in a preferred embodiment of the crystalline unsaturated polyester resin composition for a battery holder of the present invention, from the viewpoint of moldability, the ash content of the resin composition after heating the resin composition at 625°C for 3 hours is 30 to 75%.

[0024] The crystalline unsaturated polyester resin composition of the present invention is characterized in that it consists of a crystalline unsaturated polyester resin composition. This is because the inventors have repeatedly studied the above problems in the resin composition for a battery holder using an unsaturated polyester resin from various viewpoints, and as a result, have found that desired effects can be obtained when using a crystalline unsaturated polyester resin.

[0025] The crystalline unsaturated polyester resin in the present invention can be obtained by mixing a crystalline unsaturated polyester with a copolymerizable monomer and / or a copolymerizable polymer, etc. The copolymerizable monomer and / or the copolymerizable polymer are usually mixed with the resin together with other mixtures during the preparation of the resin composition, but they may also be mixed with the resin prior to the preparation of the resin composition.

[0026] Here, the explanation of crystalline and amorphous unsaturated polyester resins is as follows. There are two types of unsaturated polyester resins: amorphous unsaturated polyester resins and crystalline unsaturated polyester resins. Amorphous unsaturated polyester resins dissolved in a copolymerizable monomer such as a styrene monomer are common.

[0027] Unsaturated polyester resin compositions that can be injection-molded and use common copolymerizable monomers such as styrene monomers are known as wet BMCs at normal temperature. BMCs use amorphous unsaturated polyester resins, and (a) when injecting BMC, ancillary equipment such as a plunger pushed into the molding machine is required, (b) due to being in a块状 form, they are inferior in handling properties and workability because they are amorphous, and (c) due to being wet, they are inferior in storage stability. These are some of the improvement points.

[0028] Amorphous unsaturated polyester resin compositions that can be injection-molded and are solid at normal temperature solve the above problems (a) to (c) by using a copolymerizable monomer, a copolymerizable polymer that is solid at normal temperature, and a copolymerizable monomer that is liquid within the usable range in amorphous unsaturated polyesters. On the other hand, the inventors focused on the fact that crystalline unsaturated polyesters can combine liquid or solid copolymerizable monomers and copolymerizable polymers in any range, and there are no restrictions on the combination of crystalline unsaturated polyesters with copolymerizable monomers and copolymerizable polymers.

[0029] The difference between conventionally used amorphous unsaturated polyesters and crystalline unsaturated polyesters is as follows: Crystalline unsaturated polyester resins, composed of a copolymerizable monomer that is liquid at room temperature, are solid at room temperature, while amorphous unsaturated polyester resins are low-viscosity liquids above the melting point of crystalline unsaturated polyester resins. However, as mentioned above, amorphous unsaturated polyester resins, composed of an amorphous unsaturated polyester copolymerizable monomer that is liquid at room temperature, are liquid at room temperature. This significant difference in properties affects handling and storage stability, and as will be evident in the examples described later, it brings advantageous effects such as good thermal conductivity and heat resistance to resin compositions, granules, and ultimately, battery holders.

[0030] The crystalline unsaturated polyester resin used for battery holders, which incorporates inorganic fillers, exhibits storage dimensional stability in a temperature range below its melting point, ensuring ease of handling.

[0031] The inventors have found that, due to the properties of such crystalline unsaturated polyester, it offers the following advantages when used in battery holders. Specifically, because crystalline unsaturated polyester resin has low viscosity in the plasticization temperature range of the resin composition during battery holder molding, inorganic fillers can be used.

[0032] Furthermore, crystalline unsaturated polyester resins, which consist of crystalline unsaturated polyester, copolymerizable monomers that are liquid at room temperature, and copolymerizable polymers within a range that does not impair the heat resistance characteristics, have low viscosity when melted, allowing for high-density filling of inorganic fillers with excellent flame retardancy and thermal conductivity.

[0033] Furthermore, in a preferred embodiment of the present invention, the crystalline unsaturated polyester resin is solid in a temperature range of 50°C or lower, from the viewpoint of storage shape stability, handling, and workability. That is, it is solid at temperatures above room temperature and below 50°C, and can be processed by crushing or extrusion pelletizing.

[0034] Furthermore, the crystalline unsaturated polyester resin composition for battery holders of the present invention may contain amorphous unsaturated polyester to the extent that it does not impair the flame retardancy and other characteristics of the present invention.

[0035] Furthermore, in a preferred embodiment of the crystalline unsaturated polyester resin composition for battery holders of the present invention, the crystalline unsaturated polyester resin is characterized by comprising 40 to 95 parts by mass of crystalline unsaturated polyester and 60 to 5 parts by mass of copolymerizable monomers and / or copolymerizable polymers. Preferably, the crystalline unsaturated polyester resin is blended in a ratio of 50 to 95 parts by mass of crystalline unsaturated polyester to 50 to 5 parts by mass of copolymerizable monomers and / or copolymerizable polymers. The above range is set because if the amount of copolymerizable monomers and / or copolymerizable polymers blended with the crystalline unsaturated polyester is greater than the above range, it may become impossible to process it into pulverized or extruded pellets, and handling properties may be significantly reduced. On the other hand, if the amount of copolymerizable monomers and / or copolymerizable polymers is less than the above range, curability may be reduced.

[0036] Furthermore, in a preferred embodiment of the crystalline unsaturated polyester resin composition for battery holders of the present invention, the copolymerizable monomer is characterized by being 50% by weight or more of the copolymerizable monomer and / or copolymerizable polymer in liquid form at room temperature relative to the total amount of copolymerizable monomer and / or copolymerizable polymer. By using a crystalline unsaturated polyester resin, even if 50% by weight or more of the copolymerizable monomer is liquid at room temperature relative to the total amount of copolymerizable monomer and / or copolymerizable polymer, a crystalline unsaturated polyester resin composition that is solid in a temperature range of 50°C or less can be obtained.

[0037] Furthermore, in a preferred embodiment of the crystalline unsaturated polyester resin composition for battery holders of the present invention, the crystalline unsaturated polyester resin is present in an amount of 10 to 35% by mass of the total composition, from the viewpoint of fluidity and heat resistance, and the amount of inorganic filler is present in an amount of 50 to 80% by mass of the total composition.

[0038] The blending ratio of the crystalline unsaturated polyester resin to the total amount of the composition is preferably in the range of 10 to 35% by weight. If it is less than 10% by weight, the fluidity may decrease and moldability may deteriorate, and if it is 35% by weight or more, the heat resistance may decrease.

[0039] The crystalline unsaturated polyester in this invention is a solid crystalline unsaturated polyester resin at room temperature, consisting of a mixture of crystalline unsaturated polyester and copolymerizable monomers and / or copolymerizable polymers, and is incompatible with acetone, styrene monomer, etc., at room temperature. At room temperature, even when acetone, styrene monomer, etc., is added to the crystalline unsaturated polyester, the crystalline unsaturated polyester does not dissolve. On the other hand, amorphous unsaturated polyester is compatible with acetone, styrene monomer, etc., and becomes liquid when acetone, styrene monomer, etc., is added to the amorphous unsaturated polyester, and the mixture of amorphous unsaturated polyester and copolymerizable monomers, etc., is a liquid resin.

[0040] Unsaturated polyesters are produced by known dehydration condensation reactions of unsaturated polybasic acids, saturated polybasic acids, and glycols, and typically have an acid value of 5 to 40 mg-KOH / g. In the production of unsaturated polyesters, crystalline unsaturated polyesters can be produced by appropriately selecting and combining the acid components of unsaturated polybasic acids and saturated polybasic acids, as well as the glycols and their respective blending ratios.

[0041] Examples of unsaturated polybasic acids include maleic acid, maleic anhydride, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and glutaconic acid.

[0042] Examples of saturated polybasic acids include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebatic acid, azelaic acid, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, hetic acid, and tetrabromphthalic anhydride.

[0043] Examples of glycols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, hydrogenated bisphenol A, bisphenol A propylene oxide compounds, cyclohexanedimethanol, and dibromoneopentyl glycol.

[0044] In the present invention, among crystalline unsaturated polyesters, crystalline unsaturated polyesters are preferred in which fumaric acid is used as the unsaturated polybasic acid and isophthalic acid or terephthalic acid as the saturated polybasic acid, and ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and cyclohexanedimethanol are used as the main glycol components.

[0045] Examples of copolymerizable monomers to be mixed with the crystalline unsaturated polyester of the present invention include vinyl aromatic compounds such as styrene monomers having a vinyl group, α-methylstyrene, vinyltoluene, and α-chlorostyrene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl lactate, vinyl butyrate, and beova monomer (manufactured by Shell Chemical Co., Ltd.); and (meth)acrylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, and n-butyl methacrylate.

[0046] Furthermore, two- or more copolymerizable monomers such as triallyl cyanurate, diethylene glycol dimethacrylate, diallyl tetrabrom phthalate, phenoxyethyl acrylate, 2-hydroxyethyl acrylate, and 1,6-hexanediol diacrylate can be used. In addition, two- or more copolymerizable monomers that are solid at room temperature, such as polyethylene glycol di(meth)acrylate, ethoxylated isocyanuric acid triacrylate, and pentaerythritol tetraacrylate, can be used. These copolymerizable monomers may be used individually or in combination of two or more.

[0047] As copolymerizable monomers, both liquid copolymerizable monomers at room temperature and solid copolymerizable monomers can be used. In this case, it is preferable that the amount of liquid copolymerizable monomers at room temperature be 50% by weight or more relative to the total amount of copolymerizable monomers and / or copolymerizable polymers. By using 50% by weight or more of liquid copolymerizable monomers at room temperature relative to the total amount of copolymerizable monomers and / or copolymerizable polymers, it becomes possible to increase the filling capacity of the filler contained in the resin composition, thereby improving heat resistance. The ratio of liquid copolymerizable monomers at room temperature relative to the total amount of copolymerizable monomers and / or copolymerizable polymers is preferably 70% by weight or more, more preferably 90% by weight or more. Styrene monomer, methyl methacrylate, and diethylene glycol dimethacrylate can be suitably used as liquid copolymerizable monomers at room temperature. Amorphous unsaturated polyester resin compositions consisting of amorphous unsaturated polyester and copolymerizable monomers that are liquid at room temperature may have reduced tactile drying properties, potentially leading to decreased workability and storage stability. However, copolymerizable polymers can be used as long as fluidity during molding is not impaired. Diallyl phthalate prepolymers can be used as copolymerizable polymers.

[0048] In the crystalline unsaturated polyester resin composition for battery holders of the present invention, an inorganic filler may be incorporated. In a preferred embodiment, the inorganic filler is characterized by containing at least one of the following: aluminum hydroxide, alumina, magnesium hydroxide, magnesium oxide, calcium carbonate, magnesium carbonate, barium carbonate, calcium hydroxide, and mica. Of these, aluminum hydroxide is preferred from the viewpoint of flame retardancy. These may be used individually or in combination of two or more.

[0049] Furthermore, in a preferred embodiment of the crystalline unsaturated polyester resin composition for battery holders of the present invention, the average particle size of the inorganic filler is preferably in the range of 0.1 to 50 μm, more preferably 1.0 to 30 μm, from the viewpoint of fluidity. The average particle size can be measured by laser diffraction / scattering.

[0050] Furthermore, in a preferred embodiment of the crystalline unsaturated polyester resin composition for battery holders of the present invention, from the viewpoint of heat dissipation, the inorganic filler is 50 to 80% by mass, preferably 55 to 75% by mass, relative to the total amount of the resin composition.

[0051] In the crystalline unsaturated polyester resin composition for battery holders of the present invention, a reinforcing material can be incorporated. By using a reinforcing material, an unsaturated polyester resin composition for battery holders with excellent strength properties and dimensional stability can be obtained.

[0052] The reinforcing material used in the present invention is typically glass fiber, which is used as a reinforcing material in unsaturated polyester resin compositions used in FRP (Fiber Reinforced Plastics) such as BMC and SMC (Sheet Molding Compound). However, it is not limited to glass fiber, and other materials can also be used.

[0053] Examples of glass fibers include E-glass (alkali-free glass for electrical use), C-glass (alkali-containing glass for chemical use), A-glass (acid-resistant glass), and S-glass (high-strength glass), which are made from silicate glass and borosilicate glass. These can be used in the form of long fibers (roving) or short fibers (chopped strands). Furthermore, these glass fibers can also be used after surface treatment.

[0054] The crystalline unsaturated polyester resin composition for battery holders of the present invention, which comprises a crystalline unsaturated polyester resin, an inorganic filler, and a reinforcing material, preferably in the aforementioned proportions, has storage shape stability at temperatures below 50°C and excellent workability.

[0055] The crystalline unsaturated polyester resin composition for battery holders of the present invention may use, as a polymerization initiator, a thermal decomposition type organic peroxide or polymerization inhibitor, which are commonly used in unsaturated polyester resin compositions.

[0056] Examples of organic peroxides include t-butylperoxy-2-ethylhexyl monocarbonate, 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane, t-butylperoxyoctoate, benzoyl peroxide, methyl ethyl ketone peroxide, acetylacetone peroxide, t-butylperoxybenzoate, and dicumyl peroxide. These may be used individually or in combination of two or more.

[0057] Among these, from the viewpoint of molding conditions and storage stability, it is preferable to use an organic peroxide with a 10-hour half-life temperature of 100°C or higher, and specifically, dicumyl peroxide can be suitably used.

[0058] Examples of polymerization inhibitors include quinones such as hydroquinone, monomethyl ether hydroquinone, toluhydroquinone, di-t-4-methylphenol, monomethyl ether hydroquinone, phenothiazine, t-butylcatechol, parabenzoquinone, and pyrogallol, as well as phenolic compounds such as 2,6-di-t-butyl-p-cresol, 2,2-methylene-bis-(4-methyl-6-t-butylphenol), and 1,1,3-tris-(2-methyl-4-hydroxy-5-t-butylphenyl)butane. These may be used individually or in combination of two or more.

[0059] A mold release agent can be used with the crystalline unsaturated polyester resin composition for battery holders of the present invention. As the mold release agent, waxes such as fatty acid-based, fatty acid metal salt-based, and mineral-based waxes commonly used with thermosetting resins can be used, and in particular, fatty acid-based and fatty acid metal salt-based waxes, which have excellent heat discoloration resistance, can be preferably used.

[0060] Examples of these release agents include stearic acid, zinc stearate, aluminum stearate, and calcium stearate. These release agents may be used individually or in combination of two or more.

[0061] These release agents can be blended in an amount of 3 to 15 parts by weight per 100 parts by weight of unsaturated polyester resin. Good release properties can be ensured when the amount of release agent is within this range.

[0062] In addition to these components, the present invention may appropriately incorporate curing catalysts and polymerization inhibitors, colorants, thickeners, and other organic and inorganic additives as needed to adjust the curing conditions of the unsaturated polyester resin composition.

[0063] The unsaturated polyester resin composition for battery holders of the present invention can be manufactured by blending each component, thoroughly mixing them uniformly using a mixer, blender, etc., then preparing and granulating it using a heat-pressure kneader, extruder, etc.

[0064] Furthermore, the granular material of the present invention is characterized by being composed of the crystalline unsaturated polyester resin composition for battery holders of the present invention. The granular material made from the unsaturated polyester resin composition for battery holders of the present invention may be a powder obtained by crushing the composition, or it may be in the form of pellets.

[0065] Furthermore, the molded article of the present invention is characterized by being formed from granular material made of the crystalline unsaturated polyester resin composition for battery holders of the present invention. The molded article can be formed by conventional methods and by various thermosetting resin composition molding methods.

[0066] Furthermore, because the crystalline unsaturated polyester resin composition for battery holders of the present invention is dry-formed and has good thermal stability during melting, it can be suitably used as a molding method for melt-heat molding, such as injection molding, injection compression molding, transfer molding, and direct pressure molding.

[0067] Among these methods, injection molding using an injection molding machine is particularly suitable, as it allows for shorter molding times and the production of molded products such as battery holders with complex shapes.

[0068] Furthermore, in a preferred embodiment of the molded article of the present invention, the thermal conductivity of the molded article is characterized by being 0.8 W / m·K or higher, from the viewpoint of battery safety.

[0069] Furthermore, in a preferred embodiment of the molded article of the present invention, from the viewpoint of freedom in product design, the molded article is characterized in that, at a thickness of 0.8 mm, the flame retardancy based on the UL94 combustion test is V-0. Furthermore, in a preferred embodiment of the molded article of the present invention, the molded article is characterized in that it is a battery holder.

[0070] Furthermore, the battery pack of the present invention is characterized by comprising the battery holder of the present invention. The battery pack of the present invention is not particularly limited as long as it comprises the battery holder of the present invention, and the battery holder can be provided by conventional methods. [Examples]

[0071] The following describes in more detail one embodiment of the present invention with reference to examples, but the present invention is not limited in any way to these examples.

[0072] <Example of manufacturing a crystalline unsaturated polyester resin composition for battery holders> Examples 1-3, Comparative Example 1 The crystalline unsaturated polyester resin compositions for battery holders in Examples 1 to 3 shown in Table 1, and the thermosetting resin composition in Comparative Example 1 were blended in the amounts indicated in Table 1, uniformly prepared using a pressurized and heated kneader or stirrer, and then the prepared material was fed into an extruder for granulation or extraction to produce thermosetting resin compositions.

[0073] [Table 1]

[0074] The following ingredients were used in the formulation. (1) Thermosetting resin 1. Unsaturated polyester: Crystalline unsaturated polyester (T-855, manufactured by Nippon Yupika) 2. Epoxy acrylate: V-774 (manufactured by Nippon Yupika) 3. Reactive diluent: Styrene monomer (manufactured by Asahi Kasei Corporation)

[0075] (2) Inorganic filler 1. Inorganic filler 1: Calcium carbonate (average particle size 2 μm) 2. Inorganic filler 2: Aluminum hydroxide (average particle size 10 μm)

[0076] (3) Additives 1. Reinforcement material: Glass fiber (Nitto Boseki Co., Ltd. CS 3 PE-908) 2. Release agent: Zinc stearate (GF-200, manufactured by NOF Corporation) 3. Polymerization initiator: Dicumyl peroxide (Percumyl D, manufactured by NOF Corporation) 4. Pigment: Carbon black (manufactured by Mitsubishi Chemical Corporation) 5. Polymerization inhibitor: Parabensoquinone

[0077] <Method for evaluating physical properties>

[0078] <Thermal conductivity> The thermal conductivity was measured according to ISO 22007-2. The thermal conductivity was measured using molded articles of the thermosetting resin compositions of Examples 1 to 3 and Comparative Example 1 shown in Table 1. Molded articles of the radical polymerizable resin composition were cut to 40 mm square and 7 mm thick, and measured at 23°C using the hot disk method (thermal conductivity measuring device TPS2500S manufactured by Kyoto Electronics Manufacturing Co., Ltd.). The results are shown in Table 1. The target thermal conductivity was 0.8 W / m·K or higher.

[0079] <Flame-retardant> The flame retardancy was measured using the UL94 V-0 standard. The UL standard is an international standard established by Underwriters Laboratories, Inc. in the United States. The V-0 test was performed using molded articles of the thermosetting resin compositions shown in Examples 1 to 3 and Comparative Example 1 in Table 1. The V-0 test method was a vertical combustion test, in which a gas burner was applied to the lower end of a vertically held molded article for 10 seconds. If combustion stopped within 30 seconds, the flame was applied for another 10 seconds. The judgment criteria for the result must satisfy all of the following items. (1) None of the molded bodies continued to burn for more than 10 seconds after any of the flame contact. (2) The total burning time for 10 flame applications for 5 molded bodies shall not exceed 50 seconds. (3) After the second application of flame, no molded body remains red-hot for more than 30 seconds. (4) There is no burning molded body up to the position of the fixing clamp. (5) The molded body does not drop any burning particles that would ignite the cotton wool placed beneath it.

[0080] <ash content> The ash content was measured according to JIS K 7025. A cleaned porcelain crucible was weighed and its mass was determined to be M1. The thermosetting resin compositions of Examples 1-3 and Comparative Example 1 shown in Table 1 were placed in the porcelain crucible and weighed, and their mass was determined to be M2. The porcelain crucible containing the test specimens was placed in a muffle furnace set to 625°C and fired until a certain mass was reached. The porcelain crucible and the resulting ash were cooled to room temperature in a desiccator. This was weighed and its mass was determined to be M3. The ash content M was calculated using the following formula, with a target of 30-75% by mass. However, even if the above strict criteria are not met, conditions other than 30-75% by mass may be suitable depending on the desired application and required quality, so this should be considered as a guideline. M = 100 × [(M3 - M1) / (M2 - M1)] M: Ash content (%) M1: Mass of the porcelain crucible (g) M2: Total mass of the porcelain crucible and test specimen (g) M3: Total mass of the porcelain crucible and residue after firing (g)

[0081] <Evaluation Results> As shown in Table 1, based on a comprehensive assessment, the crystalline radical polymerizable compositions shown in Examples 1 to 3 of the present invention were found to exhibit excellent effects.

[0082] Comparative Example 1 is a thermosetting resin composition in which the resin of Example 2 is replaced with epoxy acrylate, and inorganic fillers and reinforcing materials are not used. The thermal conductivity was lower than the target, and flame retardancy of V-0 could not be achieved. Furthermore, the ash content also did not meet the target.

[0083] Based on the comprehensive assessment described above, it was found that a crystalline unsaturated polyester resin composition satisfying the requirements for thermal conductivity and ash content exhibits excellent performance as a crystalline unsaturated polyester resin composition for battery holders. In other words, it was found that the crystalline unsaturated polyester resin composition for battery holders of the present invention has the advantageous effect of providing a resin composition with high thermal conductivity, regardless of the structure of molded products such as battery holders. [Industrial applicability]

[0084] The crystalline unsaturated polyester resin composition for battery holders of the present invention has high thermal conductivity and flame retardancy, making it suitable for a wide range of applications.

Claims

1. A crystalline unsaturated polyester resin composition for a battery holder, comprising at least a crystalline unsaturated polyester resin and an inorganic filler, wherein the crystalline unsaturated polyester resin comprises a crystalline unsaturated polyester and a copolymerizable monomer and / or copolymerizable polymer.

2. The crystalline unsaturated polyester resin composition for a battery holder according to claim 1, characterized in that the ash content of the resin composition after heating the resin composition at 625°C for 3 hours is 30 to 75%.

3. The crystalline unsaturated polyester resin composition for a battery holder according to claim 1 or 2, characterized in that the inorganic filler is 50 to 80% by mass of the total amount of the resin composition.

4. The crystalline unsaturated polyester resin composition for a battery holder according to claim 1 or 2, characterized in that the inorganic filler contains at least one of aluminum hydroxide, alumina, magnesium hydroxide, and magnesium oxide.

5. The crystalline unsaturated polyester resin composition for a battery holder according to claim 1 or 2, characterized in that the average particle size of the inorganic filler is in the range of 0.1 to 50 μm.

6. Granular material made of the crystalline unsaturated polyester resin composition for battery holders according to claim 1 or 2.

7. A molded article characterized by being formed from granular material made of the crystalline unsaturated polyester resin composition for battery holders described in claim 6.

8. The molded article according to claim 7, characterized in that the thermal conductivity of the molded article is 0.8 W / m·K or higher.

9. The molded article according to claim 7, characterized in that the flame retardancy based on the UL94 combustion test is V-0 at a thickness of 0.8 mm.

10. The molded product is a battery holder, as described in claim 7.

11. A battery pack comprising the battery holder according to claim 10.

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