Battery pack member and battery pack

Abstract

Provided is a battery pack member which includes a liquid crystal polyester and glass fibers, wherein: the length weighted average fiber length of the glass fibers is 0.3 mm or more; and the content of the glass fibers is 20% by mass to 70% by mass with respect to a total content of 100% by mass of the liquid crystal polyester and the glass fibers.

Description

Battery pack components and battery packs

[0001] This application claims priority to Japanese Patent Application No. 2023-139117, filed on August 29, 2023, the contents of which are incorporated herein by reference.

[0002] In recent years, efforts to replace conventional metal parts with plastic parts have been considered in order to reduce the weight of vehicle bodies. Strength is one of the basic performance requirements for battery peripheral components installed in electric vehicles, etc., and high-strength materials are also required for the components that make up the battery pack that houses and protects the battery.

[0003] Patent Document 1 discloses long glass fiber reinforced polyamide resin composition pellets that are said to be capable of achieving high strength and high rigidity while being thin-walled, and that are flame retardant, impact resistance, chemical resistance, dimensional stability, and weldability.

[0004] JP 2017-82028 A

[0005] However, there is room for improvement in flame retardancy of the polyamide resin composition disclosed in Patent Document 1. An object of the present invention is to provide a battery pack member that can achieve both strength and flame retardancy.

[0006] The present inventors have conducted extensive research to solve the above problems and have found that a molded article containing a liquid crystalline polyester and glass fiber has sufficient strength, such as creep resistance, and excellent flame retardancy, and is therefore suitable as a battery pack component, thereby completing the present invention.

[0007] <1> A battery pack member comprising: a liquid crystal polyester; and glass fibers, wherein the glass fibers have a length-weighted average fiber length of 0.3 mm or more; and wherein the content of the glass fibers is 20% by mass or more and 70% by mass or less relative to 100% by mass of a total content of the liquid crystal polyester and the glass fibers.

[0008] <2> The battery pack member according to <1>, wherein the glass fibers have a length-weighted average fiber length of 0.6 mm or more. <3> The battery pack member according to <1> or <2>, wherein the glass fibers have a number average fiber diameter of 5 μm or more and 35 μm or less.

[0009] <4> The battery pack member according to any one of <1> to <3>, wherein the glass fibers include glass fibers having a fiber length of 1 mm or more, and a content ratio of the glass fibers having a fiber length of 1 mm or more is 30% or more with respect to a total amount (100%) of the glass fibers contained in the battery pack member.

[0010] <5> The battery pack member according to any one of <1> to <4>, further comprising a fatty acid metal salt.

[0011] <6> The battery pack member according to any one of <1> to <5>, wherein the liquid crystalline polyester contains a repeating unit represented by the following formula (1): (1) -O-Ar 1 -CO- (In formula (1), Ar 1 represents a phenylene group, a naphthylene group, or a biphenylylene group; Ar 1 Each hydrogen atom in the group represented by the formula (I) may be independently substituted with a halogen atom, an alkyl group, or an aryl group.

[0012] <7> The battery pack member according to <6>, wherein the liquid crystal polyester further contains a repeating unit represented by the following formula (2) and a repeating unit represented by the following formula (3): (2) -CO-Ar 2 -CO- (3)-X-Ar 3 -Y- (In formulas (2) to (3), Ar 2 and Ar 3 each independently represents a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4): X and Y each independently represent an oxygen atom or an imino group. 2 or Ar 3 Each hydrogen atom in the group represented by the formula (4) may be independently substituted with a halogen atom, an alkyl group, or an aryl group. 4 -Z-Ar5 - (In formula (4), Ar 4 and Ar 5 each independently represents a phenylene group or a naphthylene group; Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.

[0013] <8> A flat plate of the battery pack member having a size of 99 mm x 99 mm x 2 mm thick was used as a test piece, and the test piece was subjected to a radiation intensity test of 50 kW / m in accordance with ISO 5660-1. ２ , the total heat release measured in a 10-minute test period is 40 MJ / m ２ The battery pack member according to any one of <1> to <7>, which is:

[0014] <9> The battery pack member according to any one of <1> to <8>, which is an upper cover, a lower cover, a shock absorbing member, a bus bar frame, an enclosure, a blanket, or a housing of a battery pack.

[0015] <10> A battery pack including a battery and the battery pack member according to any one of <1> to <9>.

[0016] According to the present invention, it is possible to provide a battery pack member that is both strong and flame-retardant.

[0017] FIG. 1 is a schematic diagram illustrating an example of a battery pack.

[0018] Hereinafter, embodiments of the battery pack member of the present invention will be described.

[0019] <Battery Pack Component> A battery pack component according to an embodiment includes a liquid crystal polyester and glass fibers, wherein the glass fibers have a length-weighted average fiber length of 0.3 mm or more, and the content of the glass fibers is 20% by mass or more and 70% by mass or less relative to 100% by mass of the total content of the liquid crystal polyester and the glass fibers.

[0020] The battery pack member of the embodiment contains liquid crystal polyester and glass fiber, and therefore achieves both strength and flame retardancy.

[0021] A battery pack may include a structure in which a battery and various battery-related components are packaged together. In addition to the battery, the battery pack may also include various battery control modules, wiring, and the like. In this specification, "battery pack components" refer to components that constitute a battery pack. The battery pack components can house, connect, or protect the battery or other structures included in the battery pack. In an embodiment, the battery pack components may be an upper cover, a lower cover, a shock-absorbing component, a bus bar frame, an enclosure, a blanket, or a housing of the battery pack.

[0022] The type of battery is not particularly limited, but may be a rechargeable storage battery, preferably a lithium ion battery, and may be in the form of a battery module in which a plurality of battery cells are connected together.

[0023] FIG. 1 is a schematic diagram showing an example of a battery pack. The battery pack 1 shown in FIG. 1 includes a box-shaped battery module 10 sandwiched between an upper cover 12 and a lower cover 14. Shock-absorbing members 16a and 16b are disposed on the sides of the battery pack 1 so as to face each other. A blanket 21 is inserted between the battery module 10 and the upper cover 12. A cooling plate 50 and a blanket 22 are inserted between the battery module 10 and the lower cover 14, in this order, from the lower cover 14 side. A battery junction box 30 is connected to the top surface of the upper cover 12. A connector 42 and battery control units 46a and 46b are connected to one side of the battery module 10. Bus bars 44 are embedded in recesses between the battery modules 10.

[0024] In the battery pack 1, battery pack components include an upper cover 12, a lower cover 14, shock absorbing members 16a and 16b, blankets 21 and 22, a bus bar frame which is an insulator covering the bus bar 44, a housing for the battery module 10, a housing for the battery junction box 30, and housings for the battery control units 46a and 46b. The upper cover 12 and the lower cover 14 are also called a battery case, a battery cover, a battery housing, a battery shell, or a battery tray. The bus bar frame is also called a bus bar cover.

[0025] In addition to those exemplified with reference to FIG. 1 , examples of battery pack components include a battery frame, a cross member, a battery module end cap, spacers between battery cells, a battery module, a battery junction box, and a bus bar frame in a battery control unit.

[0026] In a battery pack, from the viewpoint of being able to more effectively demonstrate the flame retardancy of the battery pack members of the embodiment, the battery pack members may be arranged so that the shortest distance between the surface of the battery pack member and the surface of the battery is within 10 cm, or may be arranged so that the shortest distance is within 5 cm, or may be arranged so that the shortest distance is within 3 cm.

[0027] The battery pack is also called a battery box or the like. The battery pack is preferably for use in a vehicle such as an automobile. Examples of the vehicle include an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, and a bicycle.

[0028] The battery pack member of the embodiment may be a molded article of a resin composition, the resin composition including a liquid crystal polyester and glass fibers, the length-weighted average fiber length of the glass fibers being 0.3 mm or more, and the content of the glass fibers being 20% ​​by mass or more and 70% by mass or less relative to 100% by mass of the total content of the liquid crystal polyester and the glass fibers. The molded article is preferably an injection-molded article.

[0029] The battery pack member of the embodiment can contain liquid crystal polyester, glass fiber, and optional components that may be contained as needed, with the total content (mass %) of these components not exceeding 100 mass % of the total mass of the battery pack member (100 mass %).

[0030] The liquid crystal polyester and glass fiber contained in the battery pack member of the embodiment, as well as optional components that may be contained as needed, will be described below.

[0031] <Liquid Crystal Polyester> The liquid crystal polyester contained in the battery pack member of the present embodiment is not particularly limited as long as it is a polyester resin that exhibits liquid crystallinity in a molten state. The liquid crystal polyester is preferably one that melts at a temperature of 450° C. or less.

[0032] The flow initiation temperature of the liquid crystalline polyester is preferably 250° C. or higher, more preferably 270° C. or higher, and even more preferably 280° C. or higher. The flow initiation temperature of the liquid crystalline polyester is preferably 400° C. or lower, more preferably 360° C. or lower, and even more preferably 340° C. or lower.

[0033] For example, the flow initiation temperature of the liquid crystal polyester is preferably 250°C or higher and 400°C or lower, more preferably 270°C or higher and 360°C or lower, and even more preferably 280°C or higher and 340°C or lower.

[0034] In this specification, the flow initiation temperature of the liquid crystalline polyester is measured by subjecting the liquid crystalline polyester to a pressure of 9.8 MPa (100 kg / cm) using a flow tester. ２ When the liquid crystal polyester is melted under a load of 1000 kJ / cm2 at a temperature increasing rate of 4° C. / min and extruded through a nozzle having an inner diameter of 1 mm and a length of 10 mm, the liquid crystal polyester exhibits a viscosity of 4800 Pa·s (48,000 poise).

[0035] The liquid crystal polyester is preferably a wholly aromatic liquid crystal polyester having only repeating units derived from aromatic compounds.

[0036] In this specification, the term "derived from" means that during polymerization of the raw material monomer, the chemical structure of the functional group that contributes to polymerization changes, but other chemical structures do not change. The term "derived from" as used herein is a concept that also encompasses cases where the raw material monomer is derived from a polymerizable derivative thereof.

[0037] Examples of polymerizable derivatives of compounds having a carboxyl group, such as aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids, include esters in which the carboxyl group is converted to an alkoxycarbonyl group or an aryloxycarbonyl group; acid halides in which the carboxyl group is converted to a haloformyl group; and acid anhydrides in which the carboxyl group is converted to an acyloxycarbonyl group.

[0038] Examples of polymerizable derivatives of compounds having a hydroxyl group, such as aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxyamines, include acylated products in which the hydroxyl group is acylated to convert it into an acyloxyl group, etc. Examples of polymerizable derivatives of compounds having an amino group, such as aromatic hydroxyamines and aromatic diamines, include acylated products in which the amino group is acylated to convert it into an acylamino group, etc.

[0039] The liquid crystal polyester preferably has a repeating unit represented by the following formula (1) (hereinafter also referred to as "repeating unit (1)"), and more preferably has the repeating unit (1), a repeating unit represented by the following formula (2) (hereinafter also referred to as "repeating unit (2)"), and a repeating unit represented by the following formula (3) (hereinafter also referred to as "repeating unit (3)").

[0040] (1) -O-Ar １ -CO- (2) -CO-Ar ２ -CO- (3)-X-Ar ３ -Y- (wherein, Ar １ represents a phenylene group, a naphthylene group, or a biphenylylene group. ２ and Ar ３ each independently represents a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4): X and Y each independently represent an oxygen atom or an imino group (—NH—).１ , Ar ２ or Ar ３ Each hydrogen atom in the group represented by the formula (I) may be independently substituted with a halogen atom, an alkyl group, or an aryl group.

[0041] (4)-Ar ４ -Z-Ar ５ - (wherein, Ar ４ and Ar ５ each independently represents a phenylene group or a naphthylene group; Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.

[0042] Ar １ , Ar ２ or Ar ３ Examples of halogen atoms that can substitute for hydrogen atoms in include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0043] Ar １ , Ar ２ or Ar ３ Examples of the alkyl group that can substitute for a hydrogen atom in include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-hexyl group, a 2-ethylhexyl group, an n-octyl group, and an n-decyl group, and an alkyl group having 1 to 10 carbon atoms is preferred. The alkyl group may be linear or branched.

[0044] Ar １ , Ar ２ or Ar ３ Examples of aryl groups that can substitute for hydrogen atoms in include phenyl, o-tolyl, m-tolyl, p-tolyl, 1-naphthyl, and 2-naphthyl groups, with aryl groups having 6 to 20 carbon atoms being preferred. The aryl group may be a monocyclic group or a condensed ring. The aryl group may also be a group in which a hydrogen atom on an aromatic ring is substituted with an alkyl group, such as a tolyl group.

[0045] Ar １ , Ar ２ or Ar ３When a hydrogen atom of is substituted with the above-mentioned group, the number of substitutions is preferably one or two, and more preferably one.

[0046] Examples of the alkylidene group for Z in formula (4) include a methylene group, an ethylidene group, an isopropylidene group, an n-butylidene group, and a 2-ethylhexylidene group, and an alkylidene group having 1 to 10 carbon atoms is preferred.

[0047] The repeating unit (1) may be Ar １ A repeating unit in which is a 1,4-phenylene group or a repeating unit in which is a 2,6-naphthylene group is preferred.

[0048] The repeating unit (2) may be Ar ２ is preferably a repeating unit in which Ar is a 1,4-phenylene group, a 1,3-phenylene group, a 2,6-naphthylene group, a 2,7-naphthylene group, a 4,4'-biphenylylene group, or a diphenylether-4,4'-diyl group, ２ More preferred are repeating units in which R is a 1,4-phenylene group, a 1,3-phenylene group, or a 2,6-naphthylene group.

[0049] The repeating unit (3) is Ar ３ A repeating unit in which R is a 1,4-phenylene group or a repeating unit in which R is a 4,4'-biphenylylene group is preferred.

[0050] The repeating unit (3) preferably has a repeating unit in which X and Y are each an oxygen atom, since this tends to reduce the melt viscosity of the liquid crystal polyester. It is more preferable that the repeating unit (3) contains only repeating units in which X and Y are each an oxygen atom.

[0051] More specifically, the liquid crystal polyester having the repeating units (1) to (3) preferably has a repeating unit represented by the following formula (11), a repeating unit represented by the following formula (12), and a repeating unit represented by the following formula (13): (11)-O-Ar １１ -CO- (12)-CO-Ar １２ -CO- (13)-O-Ar１３ -O- (Ar １１ represents a 2,6-naphthylene group or a 1,4-phenylene group. １２ represents a 2,6-naphthylene group, a 2,7-naphthylene group, a 1,4-phenylene group, a 1,3-phenylene group, a 4,4'-biphenylylene group, or a diphenylether-4,4'-diyl group. １３ represents a 1,4-phenylene group or a 4,4'-biphenylylene group. １１ , Ar １２ or Ar １３ Each hydrogen atom in the group represented by the formula (I) may be independently substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

[0052] Preferred liquid crystal polyesters having the repeating units (11) to (13) include Ar １１ A repeating unit (11) in which Ar is a 1,4-phenylene group, and １２ A repeating unit (12) in which Ar is a 1,4-phenylene group, and １２ A repeating unit (12) in which Ar is a 1,3-phenylene group, and １３ and a repeating unit (13) in which is a 4,4'-biphenylylene group.

[0053] The number of repeating units (1) is preferably 30% or more and 80% or less, more preferably 40% or more and 70% or less, and even more preferably 45% or more and 70% or less, of the total number (100%) of all repeating units constituting the liquid crystal polyester (hereinafter referred to as the "total number of all repeating units").

[0054] The number of repeating units (2) is preferably 10% to 35%, more preferably 15% to 30%, and even more preferably 15% to 27.5%, of the total number of all repeating units.

[0055] The number of repeating units (3) is more preferably 10% to 35%, more preferably 15% to 30%, and even more preferably 15% to 27.5%, of the total number of all repeating units.

[0056] In the liquid crystal polyester having repeating units (1) to (3), for example, the number of repeating units (1) is preferably 30% or more and 80% or less of the total number of all repeating units, and the number of repeating units (2) and the number of repeating units (3) are preferably both 10% or more and 35% or less of the total number of all repeating units.

[0057] In addition, in the liquid crystal polyester, the number of repeating units (1) is 40% or more and 70% or less of the total number of all repeating units, and it is more preferable that the number of repeating units (2) and the number of repeating units (3) are both 15% or more and 30% or less of the total number of all repeating units.

[0058] Furthermore, in the liquid crystal polyester, the number of repeating units (1) is 45% or more and 70% or less of the total number of all repeating units, and the number of repeating units (2) and the number of repeating units (3) are each preferably 15% or more and 27.5% or less of the total number of all repeating units.

[0059] The ratio of the content of repeating units (2) to the content of repeating units (A3), expressed as [number of repeating units (2)] / [number of repeating units (3)], is preferably 0.9 / 1 to 1 / 0.9, more preferably 0.95 / 1 to 1 / 0.95, and even more preferably 0.98 / 1 to 1 / 0.98.

[0060] The liquid crystal polyester may have two or more types of each of the repeating units (1), (2), and (3). The liquid crystal polyester may also have repeating units other than the repeating units (1), (2), and (3), but the number of such repeating units is preferably 10% or less, more preferably 5% or less, of the total number of all repeating units.

[0061] In the liquid crystal polyester (A) containing the repeating unit (1), the repeating unit (2), and the repeating unit (3), the sum of the content of the repeating unit (1), the content of the repeating unit (2), and the content of the repeating unit (3) does not exceed 100%.

[0062] In this specification, the number of each repeating unit is determined by the analytical method described in JP 2000-19168 A. Specifically, the liquid crystal polyester is depolymerized by reacting it with a lower alcohol in a supercritical state, and the depolymerized product (monomers that derive each repeating unit) is quantified by liquid chromatography, whereby the number of each repeating unit relative to the total number of repeating units can be calculated.

[0063] The liquid crystal polyester may be used alone or in combination of two or more kinds.

[0064] The content ratio of the liquid crystal polyester relative to the total mass (100 mass%) of the battery pack components of the embodiment may be 30 mass% or more and 80 mass% or less, 40 mass% or more and 70 mass% or less, or 45 mass% or more and 60 mass% or less.

[0065] [Method for Producing Liquid Crystalline Polyester] Liquid crystal polyester can be produced by melt-polymerizing raw material monomers corresponding to the structural units that constitute it. For example, it can be produced according to the method described in Japanese Patent No. 6439027.

[0066] <Glass Fiber> The type of glass fiber in this embodiment is not particularly limited, and known glass fibers can be used, for example, E-glass (i.e., alkali-free glass), C-glass (i.e., glass for acid-resistant applications), AR-glass (i.e., glass for alkali-resistant applications), S-glass, T-glass, etc. Among these, the glass fiber is preferably E-glass.

[0067] The glass fiber may be untreated or treated. The glass fiber may be treated with a sizing agent, a silane coupling agent, a boron compound, or the like. Examples of the sizing agent include aromatic urethane-based sizing agents, aliphatic urethane-based sizing agents, and acrylic-based sizing agents.

[0068] The length-weighted average fiber length of the glass fibers contained in the battery pack member of this embodiment is 0.3 mm or more, preferably 0.6 mm or more, more preferably 1.0 mm or more, even more preferably 1.5 mm or more, particularly preferably 3.0 mm or more, and most preferably 5 mm or more. The length-weighted average fiber length of the glass fibers is preferably less than 50 mm, more preferably 40 mm or less, even more preferably 20 mm or less, and particularly preferably 15 mm or less. For example, the length-weighted average fiber length of the glass fibers is preferably 0.3 mm or more and less than 50 mm, preferably 0.6 mm or more and less than 50 mm, more preferably 1.0 mm or more and less than 40 mm, even more preferably 1.5 mm or more and less than 40 mm, particularly preferably 3.0 mm or more and less than 20 mm, and most preferably 5 mm or more and less than 15 mm.

[0069] When the length-weighted average fiber length of the glass fibers is equal to or greater than the lower limit of the preferred range, the flame retardancy of the battery pack components is improved, while when the length-weighted average fiber length is equal to or less than the upper limit of the preferred range, the battery pack components are more easily molded.

[0070] In this embodiment, the fiber length and length-weighted average fiber length of the glass fibers in the battery pack components are measured by the following procedure.

[0071] [Measurement of the length-weighted average fiber length of glass fibers] Procedure (1): Cut a test piece measuring 20 mm wide x 20 mm long x 2 mm thick from the center of a battery pack component. Procedure (2): Heat the test piece in a muffle furnace at 500-600°C for 1-4 hours to remove the resin. Procedure (3): Disperse the test piece cut out in procedure (2) (from which the resin has been removed, leaving only the glass fiber) in 1000 mL of an aqueous solution containing 0.05% by volume of a surfactant (e.g., Micro90, manufactured by INTERNATIONAL PRODUCTS CORPORATION) to prepare a dispersion. Procedure (4): Take 100 mL of the dispersion and dilute it 5-15 times with pure water. 50 mL of the diluted dispersion is taken out and the glass fibers are dispersed in a petri dish. Subsequently, the glass fibers dispersed in the petri dish are observed using a microscope (for example, VH-ZST manufactured by KEYENCE Corporation, magnification 20x), and 10 images are taken for each sample so that the photographed areas do not overlap. Step (5): The lengths of all glass fibers present in one photographed image are measured using the measurement tool of the microscope. Note that bent glass fibers are measured by multi-point measurement. The same operation is performed sequentially on the 10 photographed images until the total number of measured glass fibers exceeds 500, and the fiber lengths of the glass fibers are measured. Step (6): From the fiber lengths of the glass fibers measured in step (5), the length-weighted average fiber length lm = (Σli ２ x ni) / (Σli x ni) is calculated (Σni>500), where li is the fiber length of the glass fiber, and ni is the number of glass fibers with fiber length li.

[0072] The glass fibers contained in the battery pack member may include glass fibers having a fiber length of 1 mm or more. The content ratio of glass fibers having a fiber length of 1 mm or more in the battery pack member is preferably 30% or more, more preferably 60% or more, and even more preferably 80% or more, relative to the total amount of the glass fibers contained in the battery pack member (100%). The higher the content ratio of glass fibers having a fiber length of 1 mm or more, the more preferable, but the upper limit may be, for example, 99% or less, or 95% or less. For example, the content ratio of glass fibers having a fiber length of 1 mm or more in the battery pack member is preferably 30% or more and 99% or less, more preferably 60% or more and 99% or less, and even more preferably 80% or more and 95% or less, relative to the total amount of the glass fibers contained in the battery pack member (100%). When the content ratio of glass fibers having a fiber length of 1 mm or more is within the above-mentioned preferred range, the flame retardancy of the battery pack member is further improved.

[0073] In this embodiment, the content ratio of glass fibers having a fiber length of 1 mm or more in the battery pack components is a value obtained by the following measurement method.

[0074] [Measurement of the proportion of glass fibers with a fiber length of 1 mm or more] Using the data on the fiber length of the glass fibers measured in step (5) of [Measurement of the length-weighted average fiber length of glass fibers] above, the total fiber length of the glass fibers with a fiber length of 1 mm or more divided by the total fiber length of the fibers is used as the proportion (%) of the glass fibers with a fiber length of 1 mm or more to the total amount of glass fibers contained in the battery pack components (100%).

[0075] The fineness of the glass fibers contained in the battery pack members of this embodiment is not particularly limited, but is preferably 200 g / 1000 m or more, more preferably 500 g / 1000 m or more, and even more preferably 800 g / 1000 m or more. The fineness of the glass fibers is preferably 3750 g / 1000 m or less, more preferably 3200 g / 1000 m or less, and even more preferably 2500 g / 1000 m or less. That is, the fineness of the glass fibers contained in the battery pack members is preferably 200 g / 1000 m or more and 3750 g / 1000 m or less, and more preferably 800 g / 1000 m or more and 2500 g / 1000 m or less.

[0076] In this specification, the term "fineness" refers to the thickness of a bundle of glass fibers aligned in one direction (thickness of the fiber bundle).

[0077] The number average fiber diameter of the glass fibers contained in the battery pack components is not particularly limited, but is preferably 5 μm or more and 35 μm or less, more preferably 10 μm or more and 25 μm or less, and even more preferably 10 μm or more and 20 μm or less.

[0078] The number-average fiber diameter of the glass fibers contained in the battery pack components can be measured, for example, by removing the resin components using the same method as in step (1) of the above-mentioned [Measurement of the Length-Weighted Average Fiber Length of Glass Fibers], observing the resulting glass fibers under a scanning electron microscope (1000x magnification), and measuring the fiber diameters of 500 randomly selected glass fibers. If the number-average fiber diameter of the glass fibers is equal to or greater than the lower limit of the above-mentioned preferred range, the glass fibers are easily dispersed in the battery pack components. On the other hand, if the number-average fiber diameter is equal to or less than the upper limit of the above-mentioned preferred range, the glass fibers effectively exhibit the effect of improving the strength of the battery pack components.

[0079] In the battery pack member of the embodiment, the content of the glass fiber relative to the total content of the liquid crystal polyester and the glass fiber (100% by mass) is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. In the battery pack member of the embodiment, the content of the glass fiber relative to the total content of the liquid crystal polyester and the glass fiber (100% by mass) is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 55% by mass or less. For example, in the battery pack member of the embodiment, the content of the glass fiber relative to the total content of the liquid crystal polyester and the glass fiber (100% by mass) is preferably 20% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 60% by mass or less, and even more preferably 40% by mass or more and 55% by mass or less. When the content of the glass fiber relative to the total content of the liquid crystal polyester and the glass fiber (100% by mass) is equal to or greater than the lower limit of the above preferred range, the flame retardancy of the battery pack member is further improved. In addition, the strength of the battery pack member is improved, particularly the creep resistance. When the content of the glass fiber relative to the total content of the liquid crystal polyester and the glass fiber (100% by mass) is equal to or less than the upper limit of the above-mentioned preferable range, the battery pack members can be more easily molded.

[0080] In another aspect, the battery pack member of the embodiment preferably has a glass fiber content of 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, relative to 100% by mass of the battery pack member. In another aspect, the battery pack member of the embodiment preferably has a glass fiber content of 70% by mass or less, more preferably 60% by mass or less, and even more preferably 55% by mass or less, relative to 100% by mass of the battery pack member. For example, the battery pack member of the embodiment preferably has a glass fiber content of 20% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 60% by mass or less, and even more preferably 40% by mass or more and 55% by mass or less, relative to 100% by mass of the battery pack member.

[0081] <Optional Components> In addition to the liquid crystal polyester and glass fiber described above, the battery pack member of the embodiment may contain, as necessary, one or more optional components such as fillers other than glass fiber, additives, etc. It is preferable that the battery pack member of the embodiment does not contain any fibrous fillers other than glass fiber.

[0082] Examples of additives include metering stabilizers, flame retardants, conductivity imparting agents, crystal nucleating agents, ultraviolet absorbers, antioxidants, vibration dampers, antibacterial agents, insect repellents, deodorizing agents, coloration inhibitors, heat stabilizers, release agents, antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, foam control agents, viscosity adjusters, and surfactants.

[0083] (Fatty Acid Metal Salt) The battery pack member of the embodiment may further include a fatty acid metal salt. The fatty acid metal salt is preferably a higher fatty acid metal salt. The fatty acid metal salt may be contained as the above-mentioned metering stabilizer.

[0084] As used herein, a "higher fatty acid metal salt" refers to a metal salt of a long-chain fatty acid having 12 or more carbon atoms. The carbon number is preferably 12 to 28, and more preferably 12 to 18. Specific examples of such long-chain fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, behenic acid, and montanic acid. By including a fatty acid metal salt in the battery pack member of the embodiment, the stability of the metering time during molding can be improved and the metering time during molding can be shortened. This reduces breakage of glass fibers during molding, improving the strength of the battery pack member.

[0085] Specific examples of the higher fatty acid metal salt in this embodiment include lithium laurate, calcium laurate, barium laurate, lithium stearate, barium stearate, sodium stearate, potassium stearate, calcium stearate, aluminum stearate, magnesium behenate, calcium behenate, and barium behenate.

[0086] In this embodiment, the melting point of the fatty acid metal salt is preferably 230°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower. If the melting point of the fatty acid metal salt is equal to or lower than the above-mentioned preferred upper limit, molding at a lower temperature becomes possible, allowing the glass fibers to remain for a longer period of time, thereby improving the strength of the battery pack components. The lower limit of the melting point of the fatty acid metal salt is not particularly limited, and is, for example, 90°C or higher. For example, the melting point of the fatty acid metal salt is preferably 90°C or higher and 230°C or lower, more preferably 90°C or higher and 180°C or lower, and even more preferably 90°C or higher and 160°C or lower.

[0087] In this specification, the melting point of a fatty acid metal salt is defined as the position of the highest endothermic peak observed when measured by differential calorimetry at a temperature rise rate of 10°C / min from room temperature.

[0088] Specific examples of higher fatty acid metal salts having a melting point of 230°C or lower include calcium laurate, barium laurate, lithium stearate, barium stearate, sodium stearate, potassium stearate, calcium stearate, aluminum stearate, magnesium behenate, and calcium behenate. Of these, calcium behenate, magnesium behenate, and calcium stearate are preferred, with calcium behenate being more preferred.

[0089] The content of the fatty acid metal salt in this embodiment is preferably 0.02 to 0.15 parts by mass, more preferably 0.02 to 0.12 parts by mass, and even more preferably 0.02 to 0.08 parts by mass, relative to the mass (100 parts by mass) of the battery pack member of this embodiment excluding the content of the fatty acid metal salt. When the content of the higher fatty acid metal salt is equal to or greater than the above-mentioned preferable lower limit, the molding processability of the battery pack member is further improved. When the content of the higher fatty acid metal salt is equal to or less than the above-mentioned preferable upper limit, a decrease in the strength of the battery pack member is suppressed. Furthermore, contamination of the mold used and swelling of the molded body tend to be less likely to occur.

[0090] The battery pack member of the embodiment has excellent flame retardancy. The flame retardancy of the battery pack member of the embodiment can be evaluated by a cone calorimeter test (heat generation test) in accordance with ISO 5660-1.

[0091] The battery pack member of the embodiment is a test piece of a 99 mm x 99 mm x 2 mm thick flat plate of the battery pack member, and is measured in accordance with ISO 5660-1 with a radiation intensity of 50 kW / m ２ , the total heat release measured in a 10-minute test period is 40 MJ / m ２ Preferably, it is 35 MJ / m or less. ２ More preferably, it is 25 MJ / m or less. ２ In the battery pack member of the embodiment, a flat plate of the battery pack member having a size of 99 mm x 99 mm x 2 mm thick is used as a test piece, and the test is conducted in accordance with ISO 5660-1 to measure a radiation intensity of 50 kW / m or less. ２, the total heat generation measured in a 10-minute test period is 1 MJ / m ２ More than 40MJ / m ２ It is preferable that the concentration is 2 MJ / m or less. ２ More than 35MJ / m ２ More preferably, it is 3 MJ / m or less. ２ 25MJ / m or more ２ It is even more preferable that:

[0092] The battery pack member of the embodiment is a test piece of a 99 mm x 99 mm x 2 mm thick flat plate of the battery pack member, and is measured in accordance with ISO 5660-1 with a radiation intensity of 50 kW / m ２ , 10 minutes after the start of heating, the maximum heat generation rate is 200 kW / m for 10 seconds or more ２ It is preferable not to exceed

[0093] The battery pack member of the embodiment is a test piece of a 99 mm x 99 mm x 2 mm thick flat plate of the battery pack member, and is measured in accordance with ISO 5660-1 with a radiation intensity of 50 kW / m ２ The maximum heat release rate measured in a 10-minute test period is 200 kW / m ２ Preferably, it is less than 150 kW / m ２ More preferably, it is 140 kW / m or less. ２ In the battery pack member of the embodiment, a flat plate of the battery member having dimensions of 99 mm x 99 mm x 2 mm thick is used as a test piece, and the test results are measured in accordance with ISO 5660-1 and show a radiation intensity of 50 kW / m or less. ２ , the maximum heat release rate measured in a 10-minute test period is 10 kW / m ２ More than 200kW / m ２ Preferably, it is less than 20 kW / m ２ More than 150kW / m ２ More preferably, it is 30 kW / m or less. ２ More than 140kW / m ２ It is even more preferable that:

[0094] The battery pack member of the embodiment has excellent strength. The strength of the battery pack member of the embodiment can be evaluated based on the values ​​measured for the following test specimen in the "Bending Creep Test" described below.

[0095] [Bending Creep Test] A multipurpose test piece (Type A1) (thickness: 4 mm) conforming to JIS K7139 was molded from the battery pack member of the embodiment, and this was cut into a size of 10 mm x 80 mm to serve as a test piece. A three-point load bending creep test conforming to ISO899-2 (Plastics - Test method for creep properties) was carried out under the conditions of a load of 123 MPa, a load time of 500 hours, and a measurement temperature of 23°C.

[0096] Regarding the strength of the battery pack components, as an example, the smaller the strain (%) measured in the bending creep test, the higher the creep resistance, and the strain is preferably 1.50% or less, more preferably 1.35% or less, and even more preferably 1.20% or less.

[0097] <<Method for manufacturing battery pack member>> Examples of the method for manufacturing a battery pack member include molding a resin composition into a desired shape of a battery pack member, wherein the resin composition contains a liquid crystal polyester and glass fibers, the glass fibers have a length-weighted average fiber length of 0.3 mm or more, and the content of the glass fibers is 20% by mass or more and 70% by mass or less relative to 100% by mass of the total content of the liquid crystal polyester and the glass fibers.

[0098] The resin composition can be obtained by mixing the liquid crystal polyester, the glass fiber, and optional components used as needed all at once or in an appropriate order. The resin composition may be provided in the form of pellets.

[0099] In the manufacturing method of the battery pack member of the embodiment, the liquid crystal polyester, glass fiber, and optional components, as well as the amounts thereof, can be exemplified by the same components and amounts as those described above in the <<Battery Pack Member>>.

[0100] A method for manufacturing a battery pack member according to an embodiment may include melt-molding the resin composition.

[0101] Examples of melt molding methods include injection molding, extrusion molding such as the T-die method and inflation method, compression molding, blow molding, vacuum molding, and press molding.

[0102] A method for manufacturing a battery pack member may include injection molding the resin composition.

[0103] For example, when pellets of the resin composition are used as a molding material and molded by injection molding, the pellets of the resin composition can be melted using a known injection molding machine and the molten pellets of the resin composition can be injected into a mold to mold the resin composition.

[0104] The temperature conditions for injection molding are determined appropriately depending on the type of liquid crystal polyester. Other injection conditions such as mold temperature, screw rotation speed, back pressure, injection speed, dwell pressure, and dwell time may be appropriately adjusted.

[0105] According to the manufacturing method of the battery pack member of the embodiment, the battery pack member of the above embodiment can be manufactured.

[0106] The battery pack member in the manufacturing method of the battery pack member of the embodiment may be the same as the battery pack member described in <Battery Pack Member> of the above embodiment, and preferably may be the battery pack member described in any one of <1> to <9>.

[0107] <<Use>> In another aspect, the present invention provides a use of a molded body containing a liquid crystal polyester and a glass fiber as a battery pack member, in which the glass fiber has a length-weighted average fiber length of 0.3 mm or more, and the content of the glass fiber relative to 100 mass% of the battery pack member is 20 mass% or more and 70 mass% or less.

[0108] When used as a battery pack member, the liquid crystal polyester, glass fiber, and optional components, as well as the amounts thereof, can be exemplified by the same components and amounts as those described in the "Battery Pack Member" of the above embodiment.

[0109] The molded article used as a battery pack member of the embodiment may be the same as the battery pack member described in <Battery Pack Member> of the above embodiment, and preferably may be the battery pack member described in any one of <1> to <9>.

[0110] In one embodiment, a molded body containing a liquid crystal polyester and glass fibers is used as a battery pack member, wherein the length-weighted average fiber length of the glass fibers contained in the molded body is 0.3 mm or more, preferably 0.3 mm or more and less than 50 mm, more preferably 0.6 mm or more and less than 50 mm, even more preferably 1.5 mm or more and 40 mm or less, particularly preferably 3.0 mm or more and 20 mm or less, and most preferably 5 mm or more and 15 mm or less, and the content of the glass fibers relative to 100 mass% of the molded body is 20 mass% or more and 70 mass% or less, and 30 mass% or more and 60 mass% or less. The content of glass fibers having a fiber length of 1 mm or more contained in the molded body is preferably 30% or more, more preferably 60% or more, and even more preferably 80% or more, relative to 100% of the total amount of the glass fibers contained in the molded body. The liquid crystalline polyester contains a repeating unit represented by the following formula (11), and preferably the liquid crystalline polyester further contains a repeating unit represented by the following formula (12) and a repeating unit represented by the following formula (13) in addition to the repeating unit represented by the following formula (11). １１ -CO- (12)-CO-Ar １２ -CO- (13)-O-Ar １３ -O- (Ar １１ represents a 2,6-naphthylene group or a 1,4-phenylene group. １２represents a 2,6-naphthylene group, a 2,7-naphthylene group, a 1,4-phenylene group, a 1,3-phenylene group, a 4,4'-biphenylylene group, or a diphenylether-4,4'-diyl group. １３ represents a 1,4-phenylene group or a 4,4'-biphenylylene group. １１ , Ar １２ or Ar １３ Each hydrogen atom in the group represented by the formula (I) may be independently substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

[0111] In another aspect, the present invention provides a use of a resin composition containing a liquid crystal polyester and a glass fiber for producing a battery pack member, wherein the length-weighted average fiber length of the glass fiber contained in the battery pack member is 0.3 mm or more, and the content of the glass fiber relative to 100 mass% of the battery pack member is 20 mass% or more and 70 mass% or less.

[0112] The use for producing the battery pack member includes molding a resin composition containing a liquid crystal polyester and a glass fiber into the shape of the battery pack member, and the molding may be injection molding. The length-weighted average fiber length of the glass fiber contained in the battery pack member may be 0.3 mm or more, and the content of the glass fiber relative to 100 mass% of the battery pack member may be 20 mass% or more and 70 mass% or less.

[0113] The liquid crystal polyester, glass fiber, and optional components, as well as the amounts thereof, used to manufacture battery pack components can be exemplified by the same components and amounts as those described in the "Battery Pack Components" section of the above embodiment.

[0114] The battery pack member used to manufacture the battery pack member of the embodiment may be the same as the battery pack member described in <Battery Pack Member> of the above embodiment, and preferably may be the battery pack member described in any one of <1> to <9>.

[0115] In one embodiment, a resin composition containing a liquid crystal polyester and a glass fiber is used to manufacture a battery pack member, wherein the length-weighted average fiber length of the glass fiber contained in the battery pack member is 0.3 mm or more, preferably 0.3 mm or more and less than 50 mm, more preferably 0.6 mm or more and less than 50 mm, even more preferably 1.5 mm or more and 40 mm or less, particularly preferably 3.0 mm or more and 20 mm or less, and most preferably 5 mm or more and 15 mm or less, and the content of the glass fiber relative to 100 mass% of the battery pack member is 20 mass% or more and 70 mass% or less, and 30 mass% or more and 60 mass% or less. The content of glass fibers having a fiber length of 1 mm or more contained in the battery pack member is preferably 30% or more, more preferably 60% or more, and even more preferably 80% or more, relative to 100% of the total amount of the glass fibers contained in the battery pack member. The liquid crystal polyester contains a repeating unit represented by the following formula (11), and preferably the liquid crystal polyester further has a repeating unit represented by the following formula (12) and a repeating unit represented by the following formula (13) in addition to the repeating unit represented by the following formula (11). １１ -CO- (12)-CO-Ar １２ -CO- (13)-O-Ar １３ -O- (Ar １１ represents a 2,6-naphthylene group or a 1,4-phenylene group. １２ represents a 2,6-naphthylene group, a 2,7-naphthylene group, a 1,4-phenylene group, a 1,3-phenylene group, a 4,4'-biphenylylene group, or a diphenylether-4,4'-diyl group. １３ represents a 1,4-phenylene group or a 4,4'-biphenylylene group. １１ , Ar １２ or Ar １３ Each hydrogen atom in the group represented by the formula (I) may be independently substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

[0116] <Battery Pack> A battery pack according to an embodiment includes a battery and a battery pack member. The battery pack member includes a liquid crystal polyester and glass fibers. The glass fibers have a length-weighted average fiber length of 0.3 mm or more, and a content of the glass fibers relative to a total content of the liquid crystal polyester and the glass fibers (100% by mass) is 20% by mass or more and 70% by mass or less.

[0117] The liquid crystal polyester, glass fiber, and optional components contained in the battery pack components in the battery pack, as well as the amounts thereof, can be exemplified by the same components and amounts as those described in the "Battery Pack Components" of the above embodiment.

[0118] The battery pack members in the battery pack of the embodiment may be the same as those exemplified in <Battery Pack Members> of the above embodiment, and preferably may be the battery pack members described in any one of <1> to <9>.

[0119] The battery in the battery pack of the embodiment may be the same as that exemplified in the "Battery Pack Components" of the above embodiment, may be a rechargeable storage battery, preferably a lithium-ion battery, or may be in the form of a battery module in which a plurality of battery cells are connected.

[0120] In one embodiment, the battery pack includes a battery and a battery pack member, the battery pack member including a liquid crystal polyester and a glass fiber, the length-weighted average fiber length of the glass fiber included in the battery pack member is 0.3 mm or more, preferably 0.3 mm or more and less than 50 mm, more preferably 0.6 mm or more and less than 50 mm, further preferably 1.5 mm or more and 40 mm or less, particularly preferably 3.0 mm or more and 20 mm or less, and most preferably 5 mm or more and 15 mm or less, and the content of the glass fiber relative to 100 mass% of the battery pack member is 20 mass% or more and 70 mass% or less, and 30 mass% or less. The battery pack preferably contains glass fibers having a fiber length of 1 mm or more in a proportion of 30% or more, more preferably 60% or more, and even more preferably 80% or more, based on 100% of the total amount of the glass fibers contained in the battery pack, and the liquid crystal polyester contains a repeating unit represented by the following formula (11), and preferably the liquid crystal polyester has a repeating unit represented by the following formula (12) and a repeating unit represented by the following formula (13) in addition to the repeating unit represented by the following formula (11). １１ -CO- (12)-CO-Ar １２ -CO- (13)-O-Ar １３ -O- (Ar １１ represents a 2,6-naphthylene group or a 1,4-phenylene group. １２ represents a 2,6-naphthylene group, a 2,7-naphthylene group, a 1,4-phenylene group, a 1,3-phenylene group, a 4,4'-biphenylylene group, or a diphenylether-4,4'-diyl group. １３ represents a 1,4-phenylene group or a 4,4'-biphenylylene group. １１ , Ar １２ or Ar １３Each hydrogen atom in the group represented by the formula (I) may be independently substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

[0121] <<Method for manufacturing battery pack>> In an embodiment, the method for manufacturing a battery pack includes a step of directly or indirectly connecting a battery and a molded body, wherein the molded body contains a liquid crystal polyester and glass fibers, the glass fibers have a length-weighted average fiber length of 0.3 mm or more, and the content of the glass fibers relative to 100% by mass of the battery pack members is 20% by mass or more and 70% by mass or less.

[0122] In the manufacturing method of the battery pack of the embodiment, the liquid crystal polyester, glass fiber, and optional components, as well as the amounts thereof, can be exemplified by the same components and amounts as those described above in the <<Battery Pack Members>>.

[0123] The molded body in the manufacturing method of the battery pack of the embodiment may be the same as the battery pack member described in <Battery Pack Member> of the above embodiment, and preferably may be the battery pack member described in any one of <1> to <9>.

[0124] The battery in the battery pack manufacturing method of the embodiment may be the same as that exemplified in the "Battery Pack Member" of the above embodiment, may be a rechargeable storage battery, preferably a lithium ion battery, or may be in the form of a battery module in which a plurality of battery cells are connected.

[0125] In one embodiment, a method for manufacturing a battery pack includes a step of directly or indirectly connecting a battery and a molded body, the molded body including a liquid crystal polyester and glass fibers, and the length-weighted average fiber length of the glass fibers included in the molded body is 0.3 mm or more, preferably 0.3 mm or more and less than 50 mm, more preferably 0.6 mm or more and less than 50 mm, further preferably 1.5 mm or more and 40 mm or less, particularly preferably 3.0 mm or more and 20 mm or less, and most preferably 5 mm or more and 15 mm or less, and the content of the glass fibers relative to 100 mass% of the molded body is 20 mass% or more and 70 mass% or less. The content of glass fibers having a fiber length of 1 mm or more contained in the molded body is preferably 30% or more, more preferably 60% or more, and even more preferably 80% or more, relative to 100% of the total amount of the glass fibers contained in the molded body. The liquid crystalline polyester contains a repeating unit represented by the following formula (11), and preferably the liquid crystalline polyester has a repeating unit represented by the following formula (12) and a repeating unit represented by the following formula (13) in addition to the repeating unit represented by the following formula (11). １１ -CO- (12)-CO-Ar １２ -CO- (13)-O-Ar １３ -O- (Ar １１ represents a 2,6-naphthylene group or a 1,4-phenylene group. １２ represents a 2,6-naphthylene group, a 2,7-naphthylene group, a 1,4-phenylene group, a 1,3-phenylene group, a 4,4'-biphenylylene group, or a diphenylether-4,4'-diyl group. １３ represents a 1,4-phenylene group or a 4,4'-biphenylylene group. １１ , Ar １２ or Ar １３ Each hydrogen atom in the group represented by the formula (I) may be independently substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

[0126] <<Method>> In another aspect, the present invention provides a method for protecting a battery, the method including a step of covering the battery with a molded body, the molded body including a liquid crystal polyester and glass fibers, the glass fibers having a length-weighted average fiber length of 0.3 mm or more, and a content of the glass fibers relative to 100% by mass of the battery pack members being 20% ​​by mass or more and 70% by mass or less.

[0127] In another aspect, the present invention provides a method for flame-retarding a battery pack, the method comprising: covering a battery with a molded body; the molded body comprising a liquid crystal polyester and glass fibers; a length-weighted average fiber length of the glass fibers being 0.3 mm or more; and a content of the glass fibers relative to 100 mass% of the battery pack components being 20 mass% or more and 70 mass% or less.

[0128] Here, the battery may be completely covered with the molded body, or may be partially covered with the molded body.

[0129] The molded body in the protection method and flame retardant method of the embodiment may be the same as the battery pack member described in <Battery Pack Member> of the above embodiment, and preferably may be the battery pack member described in any one of <1> to <9>.

[0130] The molded article in the protection method and flame retardant method of the embodiment may be an upper cover, a lower cover, an impact absorbing member, a bus bar frame, an enclosure, a blanket, or a housing of the battery pack.

[0131] The battery in the protection method and flame retardant method of the embodiment may be the same as that exemplified in the "battery pack member" of the above embodiment, may be a rechargeable storage battery, preferably a lithium ion battery, or may be in the form of a battery module in which a plurality of battery cells are connected.

[0132] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0133] <<Production of Powdered Liquid Crystal Polyester (LCP1)>> p-Hydroxybenzoic acid (994.5 g, 7.2 mol), 4,4'-dihydroxybiphenyl (446.9 g, 2.4 mol), terephthalic acid (299.0 g, 1.8 mol), isophthalic acid (99.7 g, 0.6 mol), acetic anhydride (1347.6 g, 13.2 mol), and 0.9 g of 1-methylimidazole were placed in a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer, and a reflux condenser, and the atmosphere inside the reactor was thoroughly purged with nitrogen gas. Thereafter, under a nitrogen gas flow, the temperature inside the reactor was increased from room temperature to 150°C over 30 minutes, and the mixture was refluxed for 1 hour while maintained at 150°C. Next, 1-methylimidazole (0.9 g) was added to the reactor, and while distilling off by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 150°C to 320°C over 2 hours and 50 minutes. The reaction was terminated when an increase in torque was observed, and the contents were removed and cooled to room temperature to obtain a solid. The obtained solid was pulverized in a pulverizer until the particle size was approximately 0.1 to 1 mm, and then, in a nitrogen atmosphere, the temperature was raised from room temperature to 250°C over 1 hour, then from 250°C to 285°C over 5 hours, and maintained at 285°C for 3 hours, thereby carrying out solid-state polymerization. After solid-state polymerization, the mixture was cooled to obtain a powdered liquid crystal polyester (LCP1). The liquid crystal polyester (LCP1) obtained here contained 100% Ar based on the total amount of all repeating units. １ 60 mol % of repeating units (1) in which Ar is a 1,4-phenylene group, ２ 15 mol % of repeating units (2) in which Ar is a 1,4-phenylene group, ２ 5 mol % of repeating units (2) in which Ar is a 1,3-phenylene group, ３ The polymer contained 20 mol % of repeating units (3) in which the repeating unit (3) was a 4,4'-biphenylylene group, and its flow initiation temperature was 327°C.

[0134] <<Production of Powdered Liquid Crystal Polyester (LCP2)>> A reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer, and a reflux condenser was charged with p-hydroxybenzoic acid (994.5 g, 7.2 mol), 4,4'-dihydroxybiphenyl (446.9 g, 2.4 mol), terephthalic acid (239.2 g, 1.44 mol), isophthalic acid (159.5 g, 0.96 mol), and acetic anhydride (1347.6 g, 13.2 mol), and 1-methylimidazole (0.9 g) was added, and the atmosphere inside the reactor was thoroughly purged with nitrogen gas. Thereafter, under a nitrogen gas flow, the temperature inside the reactor was raised from room temperature to 150°C over 30 minutes, and the temperature was maintained at 150°C and refluxed for 1 hour. Next, 1-methylimidazole (0.9 g) was added to the reactor, and while distilling off by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 150°C to 320°C over 2 hours and 50 minutes. The reaction was terminated when an increase in torque was observed, and the contents were removed and cooled to room temperature to obtain a solid. The obtained solid was pulverized in a pulverizer until the particle size was approximately 0.1 to 1 mm, and then, under a nitrogen atmosphere, the temperature was raised from room temperature to 220°C over 1 hour, then from 220°C to 240°C over 0.5 hours, and maintained at 240°C for 10 hours, thereby carrying out solid-state polymerization. After solid-state polymerization, the mixture was cooled to obtain a powdered liquid crystal polyester (LCP2). The liquid crystal polyester (LCP2) obtained here contained 100% Ar based on the total amount of all repeating units. １ 60 mol % of repeating units (1) in which Ar is a 1,4-phenylene group, ２ 12 mol % of repeating units (2) in which Ar is a 1,4-phenylene group, ２ 8 mol % of repeating units (2) in which Ar is a 1,3-phenylene group, ３ The polymer contained 20 mol % of repeating units (3) in which the repeating unit (3) was a 4,4'-biphenylylene group, and its flow initiation temperature was 291°C.

[0135] <Production of Neat Pellets (A)> The obtained powdered liquid crystal polyester (LCP2) was granulated in a twin-screw extruder (PCM-30, manufactured by Ikegai Co., Ltd.) at a cylinder temperature of 290°C to produce neat pellets (A). The flow initiation temperature of the obtained neat pellets (A) was 284°C.

[0136] <<Production of Resin Pellets (1)>> Resin pellets (1) were produced using a production apparatus similar to that shown in FIG. 1 of JP 2021-28373 A, as follows. A GTS-40 type extruder (manufactured by Plastics Engineering Research Institute Co., Ltd.) was used as the extruder. An EBD-1500A (manufactured by Imex Co., Ltd.) was used as the belt-type take-up machine. The following glass fiber GF1 was used as the glass fiber.

[0137] [Glass fiber] GF1: Glass fiber roving (E glass, number average fiber diameter 10 μm, fineness 1400 g / 1000 m, manufactured by Nippon Electric Glass Co., Ltd.)

[0138] Resin pellets (1) were obtained in which the total of LCP1 and LCP2 was 100 parts by mass (75 parts by mass of LCP1 and 25 parts by mass of LCP2) and the glass fiber GF1 was 70 parts by mass. Specifically, the resin pellets were produced as follows.

[0139] Step of obtaining a resin structure: By operating the belt-type take-up machine, a glass fiber bundle was continuously unwound from the glass fiber roving at a take-up speed of 10 m / min. The glass fiber bundle was first heated to 150°C in the preheating section and dried. Next, the dried glass fiber bundle was fed into a die attached to the tip of the extruder, while molten LCP1 and LCP2 were introduced from the extruder through a feed port. In the die, LCP1 and LCP2 were melted at 380°C and impregnated into the glass fiber bundle. The strand diameter was adjusted at the die outlet using a die head with a nozzle diameter of 1.8 mm to obtain a resin structure containing 70 parts by mass of glass fiber per 100 parts by mass of LCP1 and LCP2 (75 parts by mass of LCP1 and 25 parts by mass of LCP2). In the resin structure obtained here, the glass fibers were aligned approximately parallel to the longitudinal direction of the liquid crystal polyester resin layer containing LCP1 and LCP2. Thereafter, the resin structure that had been heated in the die was cooled to 150° C. or less in a cooling section.

[0140] Step of obtaining pellets: Next, the cooled resin structure was taken up in the form of a strand by the belt-type take-up machine, fed to a pelletizer, and cut into a predetermined length (12 mm) in the longitudinal direction to obtain cylindrical resin pellets (1).

[0141] <<Production of Resin Pellets (2)>> Resin pellets (2) were produced in the same manner as in the production of Resin Pellets (1) above, except that a die head with a nozzle diameter of 1.3 mm was used. The obtained Resin Pellets (2) contained 165 parts by mass of glass fiber GF1 relative to a total of 100 parts by mass of LCP1 and LCP2 (75 parts by mass of LCP1 and 25 parts by mass of LCP2).

[0142] <<Production of Resin Pellets (3)>> 100 parts by mass of a total of LCP1 and LCP2 obtained above (46 parts by mass of LCP1, 54 parts by mass of LCP2) was mixed with 100 parts by mass of the following glass fiber GF2, and then melt-kneaded using a twin-screw extruder (PCM30HS, manufactured by Ikegai Corporation) to produce resin pellets (3). The melt-kneading conditions were a cylinder setting temperature of 340°C and a screw rotation speed of 150 rpm.

[0143] [Glass fiber] GF2: Glass fiber (CS-3J-260S, number average fiber length 3 mm, number average fiber diameter 11 μm, manufactured by Nitto Boseki Co., Ltd.)

[0144] <<Production of Resin Pellets (4)>> Resin pellets (4) were produced in the same manner as in the production of Resin Pellets (3) above, except that the LCP used in the production of Resin Pellets (3) was changed to 100 parts by mass of LCP1 alone.

[0145] <Production of Liquid Crystal Polyester Composition> An injection-molded article of each example was produced by a step of mixing resin pellets, neat pellets, and a metering stabilizer, or a step of mixing resin pellets and a metering stabilizer to obtain a pellet mixture, and a step of injection-molding the pellet mixture.

[0146] Example 1 Step of Obtaining a Pellet Mixture: Resin pellets (1) and neat pellets (A) were mixed in a mass ratio of 25:9, and then 0.06 parts by mass of CS-7 (calcium behenate, manufactured by Nitto Kasei Kogyo Co., Ltd.) was added as a weighing stabilizer to 100 parts by mass of the obtained mixture, and the mixture was mixed uniformly to obtain a pellet mixture.

[0147] Step of injection molding the pellet mixture: The pellet mixture was placed in the hopper of an injection molding machine TR450EH3 (manufactured by Sodick Co., Ltd.). The mixture was melt-kneaded in the injection molding machine at a melt-kneading temperature (plasticizing section) of 350°C, and injected into a mold at a mold temperature of 100°C at an injection speed of 200 mm / sec to mold a multipurpose test piece (Type A1) (thickness 4 mm) conforming to JIS K7139. Furthermore, a 150 mm x 150 mm x 2 mm thick plate-shaped molded article was molded by injection at an injection speed of 20 mm / sec. Other injection conditions: plunger temperature 360°C, screw rotation speed (plasticizing section) 100 rpm, back pressure 0.3 MPa, dwell pressure 70 MPa, dwell time 5 seconds.

[0148] Example 2 Multipurpose test pieces and flat plate-shaped molded articles were molded in the same manner as in Example 1, except that the melt-kneading temperature of the injection molding machine was changed to 300°C.

[0149] (Example 3) A multipurpose test piece and a flat plate-shaped molded body were molded in the same manner as in Example 1, except that the resin pellets (4) were used instead of the mixture of the resin pellets (1) and the neat pellets (A) in Example 1.

[0150] (Example 4) Multipurpose test pieces and flat plate-shaped molded bodies were molded in the same manner as in Example 1, except that instead of mixing the resin pellets (1) and the neat pellets (A) in Example 1, the resin pellets (2) and the neat pellets (A) were mixed in a mass ratio of 25:6.

[0151] Example 5 A multipurpose test piece and a flat plate-shaped molded article were molded in the same manner as in Example 4, except that the melt-kneading temperature of the injection molding machine was changed to 300°C.

[0152] (Example 6) A multipurpose test piece and a flat plate-shaped molded body were molded in the same manner as in Example 1, except that 100 parts by mass of resin pellets (3) were used instead of the mixture of resin pellets (1) and neat pellets (A) in Example 1.

[0153] Comparative Example 1 Glass fiber reinforced polyamide 66 (Plastron (registered trademark) PA66-GF50-01, manufactured by Polyplastics Co., Ltd.; containing 100 parts by mass of glass fiber per 100 parts by mass of PA66, pellet length 9 mm, length-weighted average fiber length of the glass fiber in the pellet 9 mm) was charged into the hopper of an injection molding machine (TR450EH3, manufactured by Sodick Co., Ltd.). The mixture was melt-kneaded in the injection molding machine at a melt-kneading temperature (plasticization zone) of 300°C, and injected into a mold at a mold temperature of 80°C at an injection speed of 200 mm / sec to mold a multipurpose test piece (Type A1) (thickness 4 mm) in accordance with JIS K7139, and then injected at an injection speed of 20 mm / sec to mold a 150 mm x 150 mm x 2 mm thick plate-like molded article. In the case of a multipurpose test piece, the gate was a one-sided gripping portion, and in the case of a flat-plate molded body, the upper side of the flat-plate molded body was a 4 mm thick film gate. Other injection conditions: plunger temperature 300°C, screw rotation speed (plasticization part) 100 rpm, back pressure 1 MPa, dwell pressure 70 MPa, dwell time 5 seconds

[0154] [Measurement of Length-Weighted Average Fiber Length of Glass Fibers] Procedure (1): A test piece measuring 20 mm wide x 20 mm long x 2 mm thick was cut from the center of the 150 mm x 150 mm x 2 mm thick flat plate molded body produced above. Procedure (2): The test piece was heated in a muffle furnace at 500-600°C for 1-4 hours to remove the resin. Procedure (3): The test piece cut out in Procedure (2) from which the resin had been removed (glass fiber only) was dispersed in 1000 mL of an aqueous solution containing 0.05 vol% of a surfactant (Micro90, manufactured by INTERNATIONAL PRODUCTS CORPORATION) to prepare a dispersion. Procedure (4): 100 mL of the dispersion was removed and diluted 5-15 times with pure water. 50 mL of the diluted dispersion was taken out and the glass fibers were dispersed in a petri dish. Subsequently, the glass fibers dispersed in the petri dish were observed under a microscope (KEYENCE Corporation, VH-ZST, 20x magnification), and 10 images were taken for each sample so that the photographed areas did not overlap. Step (5): The lengths of all the glass fibers present in one photographed image were measured using the measurement tool of the microscope. Note that, bent glass fibers were measured by multi-point measurement. The same operation was performed sequentially on the 10 photographed images until the total number of measured fibers exceeded 500, and the fiber lengths (mm) of the glass fibers were measured. Step (6): From the fiber lengths of the glass fibers measured in step (5), the length-weighted average fiber length lm = (Σli ２ × ni) / (Σli × ni) was calculated (Σni>500), where li is the fiber length of the glass fiber, and ni is the number of glass fibers with fiber length li.

[0155] [Measurement of the proportion of glass fibers having a fiber length of 1 mm or more in a molded body] The total fiber length of glass fibers having a fiber length of 1 mm or more measured in the above procedure (5) was divided by the total fiber length of the fibers, and the result was used as the proportion (%) of glass fibers having a fiber length of 1 mm or more relative to the total amount of glass fibers contained in the injection molded body (100%).

[0156] [Cone calorimeter test] The 2 mm thick plate-shaped molded product produced above was cut into a size of 99 mm x 99 mm to serve as a test piece. The test piece was subjected to a test using a cone calorimeter according to ISO 5660-1 (a test method using a cone calorimeter) with a radiation intensity of 50 kW / m ２ , total heat generation during 10 minutes of testing (MJ / m ２ ), and the heat generation rate is 200 kW / m ２ (excessive duration, s), maximum heat release rate (kW / m ２ The presence or absence of blisters of 13 mm or more was measured to evaluate the flame retardancy. The measurements were carried out using a cone calorimeter (manufactured by Toyo Seiki Seisakusho, Ltd.).

[0157] [Combustion test] The test was conducted in accordance with UL94 (6th 2022-03-11) 5 VA vertical flammability test using a 500 W test flame, except that the above-produced flat molded article measuring 150 mm x 150 mm x 2 mm thick was used as a test specimen and was continuously exposed to flame for 10 minutes. After the test, the condition of the test specimen was visually observed, and the flame retardancy was evaluated according to the following evaluation criteria.

[0158] A: The carbonized area of ​​the flame-contact surface of the test piece was about 1 / 4 of the total area, and no carbonization was observed on the back side of the flame-contact surface, indicating excellent flame retardancy. F: The carbonized area of ​​the flame-contact surface of the test piece was more than half of the total area, and carbonization was observed on the back side of the flame-contact surface, indicating poor flame retardancy.

[0159] [Bending Creep Test] The multipurpose test piece (Type A1) produced above was cut into a size of 10 mm × 80 mm to serve as a test piece, and a three-point load bending creep test in accordance with ISO 899-2 (Plastics - Test method for creep properties) was carried out under the conditions of a load of 123 MPa, a load time of 500 hours, and a measurement temperature of 23° C. A six-channel motor-controlled creep tester (manufactured by Shimadzu Access Co., Ltd.) was used for the measurement.

[0160] Table 1 shows the amount (parts by mass) of each component contained in the molded body obtained in each Example and Comparative Example, as well as the results of the above measurements.

[0161]

[0162] The molded articles of Examples 1 to 6, to which the present invention was applied, had lower values ​​in each item of the cone calorimeter test results and were superior in flame retardancy compared to the molded article of Comparative Example 1. No cracks or holes penetrating to the back surface were observed in the test pieces after the cone calorimeter test. Furthermore, the molded articles of Examples 1 to 5 also showed superior results in a combustion test based on the UL94 5 VA vertical combustion test compared to the molded article of Comparative Example 1.

[0163] In addition, in the bending creep test, the molded articles of Examples 1 to 3, although having a low glass fiber content, showed low strain values ​​of less than 2% in the bending creep test results, and thus had good creep resistance. The molded articles of Examples 4 to 6 showed lower strain values ​​in the bending creep test results than the molded article of Comparative Example 1, and thus had excellent creep resistance.

[0164] With reference to each example, the molded bodies of Examples 4 and 5, which contained glass fibers with a longer length-weighted average fiber length than the molded body of Example 6, exhibited superior flame retardancy. Similarly, the molded bodies of Examples 4 and 5, which contained a higher proportion of glass fibers with a fiber length of 1 mm or more than the molded body of Example 6, exhibited superior flame retardancy. Furthermore, the molded bodies of Examples 4 to 6, which contained 50 parts by mass of glass fiber, tended to exhibit superior flame retardancy than the molded bodies of Examples 1 to 3, which contained 30 parts by mass of glass fiber. In addition, the molded bodies of Examples 4 to 6 also tended to exhibit superior creep resistance (strength) than the molded bodies of Examples 1 to 3.

[0165] The above results show that the molded articles of the examples to which the present invention is applied have sufficient strength, such as creep resistance, and excellent flame retardancy, and can be suitably used as battery pack components.

[0166] The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to each embodiment, but is limited only by the scope of the claims.

[0167] DESCRIPTION OF SYMBOLS 1... battery pack, 10... battery module, 12... upper cover, 14... lower cover, 16a... shock absorbing member, 16b... shock absorbing member, 21... blanket, 22... blanket, 30... battery junction box, 42... connector, 44... bus bar, 46a... battery control unit, 46b... battery control unit, 50... cooling plate

Claims

1. A battery pack component comprising a liquid crystal polyester and glass fibers, wherein the glass fibers have a length-weighted average fiber length of 0.3 mm or more, and the content of the glass fibers relative to a total content of the liquid crystal polyester and the glass fibers (100 mass%) is 20 mass% or more and 70 mass% or less.

2. The battery pack member according to claim 1, wherein the length-weighted average fiber length of the glass fibers is 0.6 mm or more.

3. The battery pack member according to claim 1 or 2, wherein the number average fiber diameter of the glass fibers is 5 μm or more and 35 μm or less.

4. The battery pack member according to claim 1 or 2, wherein the glass fibers include glass fibers having a fiber length of 1 mm or more, and the content of the glass fibers having a fiber length of 1 mm or more is 30% or more relative to 100% of the total amount of the glass fibers contained in the battery pack member.

5. The battery pack component according to claim 1 or 2, further comprising a fatty acid metal salt.

6. The battery pack member according to claim 1 or 2, wherein the liquid crystal polyester contains a repeating unit represented by the following formula (1): (1) -O-Ar 1 -CO- (In formula (1), Ar 1 represents a phenylene group, a naphthylene group, or a biphenylylene group; Ar 1 Each hydrogen atom in the group represented by the formula (I) may be independently substituted with a halogen atom, an alkyl group, or an aryl group.

7. The battery pack member according to claim 6, wherein the liquid crystal polyester further comprises a repeating unit represented by the following formula (2) and a repeating unit represented by the following formula (3): (2)-CO-Ar 2 -CO- (3)-X-Ar 3 -Y- (In formulas (2) to (3), Ar 2 and Ar 3 Each of X and Y independently represents an oxygen atom or an imino group. 2 Or Ar 3 Each hydrogen atom in the group represented by the formula (4) may be independently substituted with a halogen atom, an alkyl group or an aryl group. 4 -Z-Ar 5 - (In formula (4), Ar 4 and Ar 5 each independently represents a phenylene group or a naphthylene group; Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.

8. A flat plate of the battery pack member with dimensions of 99 mm x 99 mm x 2 mm thickness was used as a test piece, and the test piece was subjected to a radiation intensity test of 50 kW / m2 in accordance with ISO 5660-1. ２ The total heat release measured over a 10-minute test period is 40 MJ / m ２ 3. The battery pack member of claim 1, wherein:

9. The battery pack member according to claim 1 or 2, which is an upper cover, a lower cover, a shock absorbing member, a bus bar frame, an enclosure, a blanket or a housing in a battery pack.

10. A battery pack comprising a battery and the battery pack member according to claim 1 or 2.

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