JP2024081072A - Battery holder - Google Patents

Abstract

[Problem] The object of the present invention is to provide a battery holder that has impact resistance to protect the batteries from external shocks and prevents short circuits between batteries. [Solution] The battery holder of the present invention is for storing multiple cylindrical batteries, and is characterized in that it is made from a material that contains resin, at least a portion of the side surface of the cylindrical batteries is surrounded by the battery holder, and the ratio R1 of the area of the side surface surrounded by the battery holder to the total area of the cylindrical battery's side surface (100%) is 10% or greater. [Selected Figure] Figure 1

Description

The present invention relates to a battery holder.

Secondary batteries are sometimes used as a power source for automobiles, etc. A secondary battery may be used as a pack by mounting multiple batteries in a single module.
Battery holders are used when mounting multiple batteries in a single module. Battery holders can also be used as trays for transporting and assembling batteries during battery manufacturing, and are used widely from auxiliary items during battery manufacturing to parts in battery packs.

An example of a battery holder is described in Patent Document 1.

JP 2005-197192 A

Secondary batteries such as lithium-ion batteries have a high risk of fire due to short circuits, etc. The battery holder described in Patent Document 1 is not made of resin and does not have sufficient insulation properties. In addition, battery holders are required to have even greater impact resistance to protect the batteries.

Therefore, the object of the present invention is to provide a battery holder that is shock-resistant to protect the battery from external shocks and prevents short circuits between batteries.

That is, the present invention is as follows.
[1]
1. A battery holder for storing a plurality of cylindrical batteries, comprising:
Made from raw materials including resin,
at least a portion of the side surface of the cylindrical battery is surrounded by the battery holder, and a ratio R1 of the area of the side surface surrounded by the battery holder to the total area of the cylindrical battery's side surface (100%) is 10% or greater;
A battery holder characterized by:
[2]
The battery holder according to [1], wherein the shape of the portion of the battery holder that houses the cylindrical battery is approximately similar to the shape of the side surface of the cylindrical battery.
[3]
The battery holder according to [1] or [2], wherein the ratio R2 of the area of the portion where the cylindrical battery contacts the side surface with the battery holder to the total area (100%) of the side surface of the cylindrical battery is 10% or greater.
[4]
The battery holder according to any one of [1] to [3], wherein the integral value J75 of the compressive strength within a strain ratio range of 0 to 0.75 per ^mm2 area calculated from the compressive strength SS curve is 0.1 to 50 N/ ^mm2 .
[5]
The battery holder according to any of [1] to [4], wherein the battery holder satisfies the relationship of formula (1) below in a test in which a battery holder housing a multiple cylindrical batteries is dropped in a direction perpendicular to the direction in which the batteries are housed:
J5×A1×d1/1000<W×g×h<J75×A1×d1/1000 ・・・(1)
(In the above formula (1), J5 is the integral value (N/mm ² ) of the compressive strength of the battery holder when the strain ratio per mm ² ranges from 0 to 0.05 as calculated from the compressive strength SS curve; J75 is the integral value (N/mm ² ) of the compressive strength of the battery holder when the strain ratio per mm ² ranges from 0 to 0.75 as calculated from the compressive strength SS curve; A1 is "(projected area of the battery when the battery located at the lowest point in the vertical direction is projected with light in the direction of fall) x (ratio of the area of the side surface of the battery surrounded by the battery holder to 100% of the total area of the side surfaces of the battery R1)/100" (mm ² ); d1 is the distance in the direction of fall from the battery located at the lowest point in the vertical direction to the end of the battery holder (mm); W is the total weight (kg) of batteries included in the area obtained by cutting the battery holder in the direction of fall at the largest cross section that has the largest area among the cross sections perpendicular to the fall direction of the battery located at the lowest point in the vertical direction; g is the acceleration of gravity (m/s ² ); and h is the fall height (m).)
[6]
The battery holder according to any one of [1] to [5], wherein the thickness of the thinnest part between the portions that house the batteries in the battery holder is greater than 0 mm and not greater than 10 mm.
[7]
The battery holder according to any one of [1] to [6], wherein the flame retardancy of the battery holder is V-2 or higher.
[8]
The battery holder according to any one of [1] to [7], wherein the battery holder has a deflection temperature under load of 90° C. or higher.
[9]
The battery holder according to any one of [1] to [8], which is made of a foam.
[10]
The battery holder according to any one of [1] to [9], which is made of a bead foam.
[11]
Further, the battery case includes a cover that surrounds at least a portion of an upper end surface and/or a lower end surface of the portion that houses the at least one battery,
The battery holder according to any one of [1] to [10], wherein the lid is made of a foam containing resin.
[12]
The battery holder according to [11], wherein the foam is a bead foam.
[13]
The battery holder according to [11], wherein the lid has an integral value J75 of compressive strength within a strain ratio range of 0 to 0.75 per ^mm2 area calculated from a compressive strength SS curve of 0.1 to 50 N/ ^mm2 .
[14]
The battery holder according to [11], wherein the thickness of the lid is greater than 0 mm and not greater than 5 mm.

The battery holder of the present invention has the above-mentioned configuration, and therefore has impact resistance that can protect the battery from external impacts and can prevent short circuits between batteries.

FIG. 2 is a schematic diagram showing an example of a battery holder according to the present embodiment. (A) is a perspective view of the battery holder with covers attached to the top and bottom, (B) is a perspective view of the battery holder without the top cover and with a battery stored in the storage compartment, and (C) is a cross-sectional view of the battery holder with the top cover taken along line X-X in (B). 1A is a schematic diagram of a battery to be housed, and FIG. 1B is a diagram for explaining a drop test of an embodiment. FIG. 4 is a diagram illustrating a drop test in which the drop direction is different from that in FIG. FIG. 11 is an explanatory diagram showing a compressive strength SS curve and calculation of compressive strength integral values J5 and J75 from the compressive strength SS curve. FIG. 2 is a perspective view of the battery holder produced in Example 1. FIG. 11 is a perspective view of the battery holder produced in Example 2. FIG. 13 is a perspective view of the battery holder produced in Example 3 etc. FIG. 11 is a perspective view of the battery holder produced in Example 4. FIG. 13 is a perspective view of the battery holder produced in Example 5. FIG. 13 is a perspective view of the battery holder produced in Example 6. FIG. 13 is a perspective view of the battery holder produced in Example 7. FIG. 13 is a perspective view of the battery holder produced in Example 8. FIG. 13 is a perspective view of the battery holder produced in Example 9. FIG. 13 is a perspective view of the battery holder produced in Example 10. FIG. 13 is a perspective view of the battery holder produced in Example 11. FIG. 13 is a perspective view of the battery holder produced in Example 14, etc. FIG. 2 is a perspective view of the battery holder produced in Comparative Example 1 etc.

The following describes in detail the form for carrying out the present invention (hereinafter referred to as the "present embodiment"). The present invention is not limited to the following description, and can be carried out in various modifications within the scope of the gist of the invention.

[Battery holder]
The battery holder of this embodiment is a battery holder for storing multiple cylindrical batteries, is made of a material containing resin, at least a portion of the side surface of the cylindrical batteries is surrounded by the battery holder, and the ratio R1 of the area of the side surface surrounded by the battery holder to the total area of the cylindrical battery side surface (100%) is 10% or greater. It is preferable that ratio R1 be 20% or greater.
Of the storage sections which are portions for storing the cylindrical batteries, at least one storage section may satisfy the ratio R1, or all storage sections may satisfy the ratio R1.

The battery holder may have a "main body" including a storage section that surrounds at least a portion of the side surface of a cylindrical battery, and a "lid" that surrounds at least a portion of the upper surface (top surface, upper end surface) and/or lower surface (bottom surface, lower end surface) of the storage section. The battery holder may consist of only the main body, or may consist of the main body and the lid. It may also include other members in addition to the main body and the lid.
The body may be made of one member or may be made of multiple members.
The body and the lid may be connected or independent.
In this specification, the side surface refers to the surface that corresponds to a rectangle when the cylinder is unfolded, and the top surface and bottom surface refer to the surfaces that correspond to a circle when the cylinder is unfolded.

It is preferable that the multiple cylindrical batteries are stored in the same direction in the battery holder. For example, the direction in which the batteries are stored (i.e., the depth direction of the storage section) may be the height direction of the cylindrical batteries (Figure 1). Also, if the main body of the battery holder is a roughly rectangular parallelepiped, the direction in which the batteries are stored may be the thickness direction (Figure 1).

＜Main unit＞
The main body is preferably made of the raw material, more preferably includes a foam made of the raw material, and is preferably made of only the foam made of the raw material.

(material)
The raw material includes a resin and may further include other components.

-resin-
The resin may be a crystalline resin, an amorphous resin, or a mixture thereof. The resin may be used alone or in the form of a mixture of two or more kinds.

--Amorphous resin--
The amorphous resin is not particularly limited as long as it is a resin having amorphous properties, and examples thereof include polyphenylene ether (PPE)-based resins such as polyphenylene ether (PPE) resin, polyphenylene ether resin/polystyrene resin alloy, polyphenylene ether resin/high impact polystyrene resin alloy, polyphenylene ether resin/polystyrene resin/high impact polystyrene resin alloy, and polyphenylene ether resin/polypropylene resin alloy; polystyrene resins such as polystyrene resin, rubber-reinforced polystyrene resin (high impact polystyrene resin), and acrylonitrile-butadiene-styrene copolymer (ABS resin); polycarbonate resins such as polycarbonate resin, polycarbonate resin/ABS resin alloy, and polycarbonate resin/polybutylene terephthalate resin alloy; polyvinyl chloride; acrylic resins; polymethyl methacrylate; polyethersulfone, polyetherimide; polyamideimide; and the like.
Among these, from the viewpoints of heat resistance, dimensional stability, and ease of molding, polyphenylene ether resins, polystyrene resins, acrylic resins, and polycarbonate resins are preferred, and polyphenylene ether resins and polystyrene resins are more preferred.

As the polyphenylene ether-based resin, for example, as described above, there can be mentioned polyphenylene ether resin, polyphenylene ether resin/polystyrene resin alloy, polyphenylene ether resin/high impact polystyrene resin alloy, polyphenylene ether resin/polystyrene resin/high impact polystyrene resin alloy, etc. For example, the alloy may contain more than 50 mass% of polyphenylene ether resin.
These may be used alone or in combination of two or more.

一般式（Ｉ）中、Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４は、それぞれ独立して、水素原子、ハロゲン原子、アルキル基、アルコキシ基、フェニル基、又はハロゲン原子と一般式（Ｉ）中のベンゼン環との間に少なくとも２個の炭素原子を有するハロアルキル基若しくはハロアルコキシ基で第３α－炭素原子を含まないもの、を示す。また、一般式（Ｉ）中、ｎは、重合度を表す整数である。上記アルキル基、アルコキシ基中の炭素数としては、１～７個であってよい。 The polyphenylene ether resin of the polyphenylene ether-based resin refers to a polymer containing a repeating unit (structural unit) represented by the following formula (I), and examples thereof include a homopolymer consisting only of a repeating unit represented by the following formula (I), and a copolymer containing a repeating unit represented by the following general formula (I). The above copolymer is a copolymer having a repeating unit represented by the following formula (I) as a main repeating unit (for example, a copolymer in which the mass ratio of the repeating unit represented by the following formula (I) is more than 50 mass% (preferably 70 mass% or more) relative to 100 mass% of the copolymer). The above polyphenylene ether resin may be used alone or in combination of two or more types.

In general formula (I), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a phenyl group, or a haloalkyl group or a haloalkoxy group having at least two carbon atoms between the halogen atom and the benzene ring in general formula (I) and not including a tertiary α-carbon atom. In addition, in general formula (I), n is an integer representing the degree of polymerization. The number of carbon atoms in the alkyl group or alkoxy group may be 1 to 7.

Specific examples of polyphenylene ether resins include poly(2,6-dimethyl-1,4-phenylene) ether, poly(2,6-diethyl-1,4-phenylene) ether, poly(2-methyl-6-ethyl-1,4-phenylene) ether, poly(2-methyl-6-propyl-1,4-phenylene) ether, poly(2,6-dipropyl-1,4-phenylene) ether, poly(2-ethyl-6-propyl-1,4-phenylene) ether, poly(2,6-dibutyl-1,4-phenylene) ether, poly(2,6-dilauryl-1,4-phenylene) ether, poly(2,6-diphenyl-1,4-diphenylene) ether, poly(2,6-dimethoxy-1 ,4-phenylene) ether, poly(2,6-diethoxy-1,4-phenylene) ether, poly(2-methoxy-6-ethoxy-1,4-phenylene) ether, poly(2-ethyl-6-stearyloxy-1,4-phenylene) ether, poly(2,6-dichloro-1,4-phenylene) ether, poly(2-methyl-6-phenyl-1,4-phenylene) ether, poly(2,6-dibenzyl-1,4-phenylene) ether, poly(2-ethoxy-1,4-phenylene) ether, poly(2-chloro-1,4-phenylene) ether, poly(2,6-dibromo-1,4-phenylene) ether and the like, but are not limited thereto. Among these, a resin containing a repeating unit in which ^R1 and ^R2 are alkyl groups having 1 to 4 carbon atoms, and ^R3 and ^R4 are hydrogen or an alkyl group having 1 to 4 carbon atoms in general formula (I) is particularly preferred, and a homopolymer consisting of only such repeating units is more preferred.

The polyphenylene ether resin is not particularly limited and can be produced by known methods. For example, it can be easily produced by oxidatively polymerizing 2,6-xylenol using a complex of cuprous salt and amine by Hay described in U.S. Pat. No. 3,306,874 as a catalyst. Other examples include methods described in U.S. Pat. Nos. 3,306,875, 3,257,357, 3,257,358, JP-B-52-17880, JP-A-50-51197, and JP-A-63-152628.

The polyphenylene ether resin may be a modified polyphenylene ether resin in which some or all of the repeating units constituting the polyphenylene ether resin are modified with an unsaturated or saturated carboxylic acid or a derivative thereof.
Examples of the modified polyphenylene ether resin include those described in JP-A-2-276823 (U.S. Pat. No. 5,159,027, U.S. Reissue Patent No. 35,695), JP-A-63-108059 (U.S. Pat. Nos. 5,214,109, 5,216,089), JP-A-59,724, and the like.
The modified polyphenylene ether resin is produced, for example, by melt-kneading and reacting the polyphenylene ether resin with an unsaturated or saturated carboxylic acid or a derivative thereof in the presence or absence of a radical initiator, or by dissolving the polyphenylene ether resin and the unsaturated or saturated carboxylic acid or a derivative thereof in an organic solvent in the presence or absence of a radical initiator and reacting them in the solution.

Examples of unsaturated carboxylic acids or derivatives thereof include maleic acid, fumaric acid, itaconic acid, halogenated maleic acid, cis-4-cyclohexene 1,2-dicarboxylic acid, endo-cis-bicyclo(2,2,1)-5-heptene-2,3-dicarboxylic acid, and the like, as well as the acid anhydrides, esters, amides, imides, and the like of these dicarboxylic acids, as well as acrylic acid, methacrylic acid, and the like, as well as the esters and amides, and the like of these monocarboxylic acids.

Furthermore, examples of saturated carboxylic acids or derivatives thereof include compounds that can be thermally decomposed at the reaction temperature during the production of modified polyphenylene ether resin and become derivatives of modified polyphenylene ether resin. Specific examples include malic acid and citric acid.

Examples of polystyrene resins that can be used in the polymer alloy of polyphenylene ether resin include homopolymers of styrene compounds, copolymers of two or more styrene compounds, and rubber-modified styrene resins (high impact polystyrene resins) in which rubber-like polymers are dispersed in particulate form in a matrix of styrene compound polymers. Examples of styrene compounds that produce these polymers include styrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, α-methylstyrene, ethylstyrene, α-methyl-p-methylstyrene, 2,4-dimethylstyrene, monochlorostyrene, and p-tert-butylstyrene.

When using a polymer alloy as described above as the polyphenylene ether resin, the polystyrene resin contained in the polyphenylene ether resin may be a copolymer obtained by combining two or more types of styrene compounds or a high impact polystyrene resin.

The weight average molecular weight (Mw) of the polyphenylene ether resin is preferably 20,000 to 60,000.
The weight average molecular weight (Mw) refers to the weight average molecular weight obtained by measuring the resin by gel permeation chromatography (GPC) and calculating the molecular weight of the peak in the chromatogram using a calibration curve (created using the peak molecular weight of the standard polystyrene) obtained from measurements of commercially available standard polystyrene.

The content of the polyphenylene ether resin is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 35 to 60% by mass, based on 100% by mass of the base resin. When the content of the PPE resin is 20% by mass or more, excellent heat resistance and flame retardancy are easily obtained. Also, when the content of the PPE resin is 80% by mass or less, excellent processability is easily obtained.
In this specification, the base resin refers to the raw materials of the battery holder excluding the foaming agent. The mass ratio of the base resin to 100 mass% of the raw materials may be 95 mass% or more, or may be 99 mass% or more.

The polystyrene-based resin refers to homopolymers of styrene and styrene derivatives, and copolymers containing styrene and styrene derivatives as main components (components contained in the polystyrene-based resin at 50% by mass or more).
Examples of the styrene derivatives include o-methylstyrene, m-methylstyrene, p-methylstyrene, t-butylstyrene, α-methylstyrene, β-methylstyrene, diphenylethylene, chlorostyrene, and bromostyrene.

Examples of the homopolymer polystyrene resin include polystyrene, poly-α-methylstyrene, and polychlorostyrene.
Examples of the polystyrene-based copolymer resin include binary copolymers such as styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, styrene-maleimide copolymer, styrene-N-phenylmaleimide copolymer, styrene-N-alkylmaleimide copolymer, styrene-N-alkyl-substituted phenylmaleimide copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-n-alkyl acrylate copolymer, styrene-n-alkyl methacrylate copolymer, and ethylvinylbenzene-divinylbenzene copolymer; ternary copolymers such as ABS and butadiene-acrylonitrile-α-methylbenzene copolymer; graft copolymers such as styrene-grafted polyethylene, styrene-grafted ethylene-vinyl acetate copolymer, (styrene-acrylic acid) grafted polyethylene, and styrene-grafted polyamide; and the like.
These may be used alone or in combination of two or more.

The polystyrene resin may be produced by any conventionally known production method.

Examples of polycarbonate-based resins include polycarbonate resins, polycarbonate resin/ABS resin alloys, polycarbonate resin/polybutylene terephthalate resin alloys, etc. For example, the alloys may contain more than 50% by mass of polycarbonate resin.
These may be used alone or in combination of two or more.

The polycarbonate resin may be a bisphenol A-type polycarbonate polymerized using bisphenol A, or any of various polycarbonates having high heat resistance or low water absorption rate polymerized using other dihydric phenol compounds.
Examples of the other dihydric phenol compounds include hydroquinone, 4,4'-dihydroxydiphenyl, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfoxide, bis(4-hydroxyphenyl)ketone, bis(4-hydroxyphenyl)ether, and halogenated bisphenols such as 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane.

In addition to linear polycarbonates, the polycarbonate resins may be branched polycarbonates polymerized with trifunctional phenols, or copolymer polycarbonates copolymerized with aliphatic dicarboxylic acids, aromatic dicarboxylic acids, or divalent aliphatic or alicyclic alcohols.

The polycarbonate resin may be produced by any conventional method.

As the acrylic resin, one or more polymers selected from the group consisting of the following (a) to (d) and mixtures thereof can be used.
(a) Homopolymers or copolymers of methacrylic acid monomers, acrylic acid monomers, methacrylic acid ester monomers, acrylic acid ester monomers, and mixtures thereof.
(b) Copolymers of a methacrylic acid monomer, an acrylic acid monomer, a methacrylic acid ester monomer, an acrylic acid ester monomer, and one or more of a styrene-based monomer and an isopropenyl aromatic monomer, and mixtures thereof.
(c) Copolymers of methacrylic acid monomers, acrylic acid monomers, methacrylic acid ester monomers, acrylic acid ester monomers with styrene-based monomers, isopropenyl aromatic monomers, and/or maleic anhydride, and mixtures thereof.
(d) Copolymers of methacrylic acid monomers, acrylic acid monomers, methacrylic acid ester monomers, acrylic acid ester monomers with styrene-based monomers, isopropenyl aromatic monomers, and/or maleic anhydride, and/or other copolymerizable monomers, and mixtures thereof.
Specific examples of the methacrylic acid ester monomer include butyl methacrylate, ethyl methacrylate, methyl methacrylate, propyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, 2-ethylhexyl methacrylate, t-butylcyclohexyl methacrylate, benzyl methacrylate, and 2,2,2-trifluoroethyl methacrylate, with methyl methacrylate being preferred.
Specific examples of the acrylic ester monomer include methyl acrylate, ethyl acrylate, butyl acrylate, isopropyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, and phenyl acrylate.
The methacrylic acid ester monomers, the acrylic acid ester monomers, the methacrylic acid monomers, and the acrylic acid monomers may be used alone or in combination of two or more kinds.
The styrene-based monomer is a monomer having a styrene skeleton in its structure. Specific examples thereof include alkyl-substituted styrenes such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, and p-tert-butylstyrene, and 1,1-diphenylethylene, with styrene being preferred.
These styrene monomers may be used alone or in combination of two or more.
Specific examples of isopropenyl aromatic monomers include alkyl-substituted isopropenylbenzenes such as α-methylstyrene, isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylpentylbenzene, isopropenylhexylbenzene, and isopropenyloctylbenzene, with α-methylstyrene being preferred.
These isopropenyl aromatic monomers may be used alone or in combination of two or more.
Specific examples of monomers other than those mentioned above that are copolymerizable with the methacrylic acid monomer, acrylic acid monomer, methacrylic acid ester monomer, and acrylic acid ester monomer include vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, maleimide monomers such as N-phenylmaleimide and N-cyclohexylmaleimide, unsaturated carboxylic acid monomers such as itaconic acid, maleic acid, and fumaric acid, unsaturated dicarboxylic acid anhydride monomers such as itaconic acid, ethylmaleic acid, methylitaconic acid, and chloromaleic acid, and conjugated diene monomers such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Two or more of these monomers may be added and copolymerized.
Among the above, more preferred acrylic resins include methyl methacrylate homopolymers and copolymers of methyl methacrylate and acrylic esters from the viewpoints of economy, mechanical properties, transparency, and weather resistance.

--Crystalline resin--
The crystalline resin is not particularly limited as long as it is a resin having crystallinity, and examples thereof include polyethylene resin, polypropylene resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene sulfide resin, polyether ether ketone resin, liquid crystal polymer, polytetrafluoroethylene resin, etc. Among them, from the viewpoints of heat resistance, moldability, and cushioning properties, polyethylene resin, polypropylene resin, and polyamide resin are preferred.

Examples of the polyethylene resin include high density polyethylene, low density polyethylene, linear low density polyethylene, copolymers of ethylene and α-olefins, and propylene-ethylene copolymers.
These may be used alone or in combination of two or more.
Furthermore, these polyethylene resins may have a crosslinked structure by using a crosslinking agent or the like.

Examples of the polyamide resin include polyamides, polyamide copolymers, and mixtures thereof. The polyamide resin may include a polymer obtained by self-condensation of an aminocarboxylic acid, ring-opening polymerization of a lactam, or polycondensation of a diamine and a dicarboxylic acid.
Examples of polyamides include nylon 66, nylon 610, nylon 612, nylon 46, nylon 1212, etc., which are obtained by polycondensation of diamine and dicarboxylic acid, and nylon 6 and nylon 12, etc., which are obtained by ring-opening polymerization of lactam.
Examples of polyamide copolymers include nylon 6/66, nylon 66/6, nylon 66/610, nylon 66/612, nylon 66/6T (T represents a terephthalic acid component), nylon 66/6I (I represents an isophthalic acid component), nylon 6T/6I, and the like.
Examples of such mixtures include mixtures of nylon 66 and nylon 6, mixtures of nylon 66 and nylon 612, mixtures of nylon 66 and nylon 610, mixtures of nylon 66 and nylon 6I, and mixtures of nylon 66 and nylon 6T.
These may be used alone or in combination of two or more.

The mass ratio of the resin to 100% by mass of the raw material is preferably 70% by mass or more, and more preferably 80% by mass or more. The mass ratio of the resin to 100% by mass of the base resin is preferably 70% by mass or more, and more preferably 80% by mass or more.

-Other ingredients-
The other components include flame retardants, flame retardant assistants, heat stabilizers, antioxidants, antistatic agents, inorganic fillers, anti-dripping agents, ultraviolet absorbers, light absorbers, plasticizers, release agents, dyes and pigments, rubber components, foaming agents, etc., and may be added within a range that does not impair the effects of the present invention. The other components may be components other than resins.

From the viewpoint of maintaining heat resistance and processability, the mass ratio of the other components in the raw materials is preferably 0 to 40 parts by mass, more preferably 0 to 30 parts by mass, and even more preferably more than 0 parts by mass and not more than 20 parts by mass, per 100 parts by mass of the resin.

The flame retardant includes organic flame retardants and inorganic flame retardants.
Examples of organic flame retardants include halogen-based compounds such as bromine compounds, phosphorus-based compounds, and non-halogen-based compounds such as silicone-based compounds.
Examples of inorganic flame retardants include metal hydroxides such as aluminum hydroxide and magnesium hydroxide, and antimony compounds such as antimony trioxide and antimony pentoxide.
These may be used alone or in combination of two or more.

Among the above flame retardants, from the viewpoints of compatibility with resins, minimizing the impact on the environment, and foaming properties when made into a foam, non-halogenated organic flame retardants are preferred, phosphorus-based flame retardants and silicone-based flame retardants are more preferred, and phosphorus-based flame retardants are even more preferred.

The phosphorus-based flame retardant may contain phosphorus or a phosphorus compound. Examples of phosphorus include red phosphorus. Examples of phosphorus compounds include phosphate esters, phosphazene compounds having a bond between a phosphorus atom and a nitrogen atom in the main chain, trialkylphosphine oxides, triphenylphosphine oxides, and the like.
Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, dimethyl ethyl phosphate, methyl dibutyl phosphate, ethyl dipropyl phosphate, hydroxyphenyl diphenyl phosphate, resorcinol bisdiphenyl phosphate, and the like. Further examples include phosphate ester compounds of the above types modified with various substituents, various condensation type phosphate ester compounds, and phosphate ester compounds having a cyclic structure.
Among these, from the viewpoints of heat resistance, flame retardancy, foaming property, and economic efficiency, phosphazene compounds, triphenyl phosphates such as bisphenol A bisphosphate, condensation type phosphate ester compounds, and phosphate ester compounds having a cyclic structure are preferred.
These may be used alone or in combination of two or more.

Furthermore, examples of silicone-based flame retardants include (mono- or poly)organosiloxanes.
Examples of the (mono- or poly)organosiloxane include monoorganosiloxanes such as dimethylsiloxane and phenylmethylsiloxane; polydimethylsiloxanes and polyphenylmethylsiloxanes obtained by polymerizing these; and organopolysiloxanes such as copolymers of these.
In the case of organopolysiloxane, the bonding groups of the main chain and the branched side chains are hydrogen, alkyl groups, and phenyl groups, preferably phenyl groups, methyl groups, ethyl groups, and propyl groups, but are not limited thereto. The terminal bonding groups may be hydroxyl groups, alkoxy groups, alkyl groups, and phenyl groups. There is no particular limitation on the shape of the silicones, and any shape such as oil, gum, varnish, powder, and pellets can be used.
These may be used alone or in combination of two or more.

The mass ratio of the flame retardant in 100% by mass of the raw materials is preferably 0 to 30 parts by mass, and more preferably 5 to 25 parts by mass, per 100 parts by mass of the resin, from the viewpoint of improving flame retardancy while minimizing the effect on heat resistance.

Examples of the inorganic fillers include fibrous inorganic fillers such as glass fibers, potassium titanate fibers, gypsum fibers, brass fibers, stainless steel fibers, steel fibers, ceramic fibers, and boron whisker fibers; plate-like inorganic fillers such as mica, talc, kaolin, calcined kaolin, and glass flakes; granular inorganic fillers such as titanium oxide, apatite, glass beads, silica, calcium carbonate, and carbon black; and needle-like inorganic fillers such as wollastonite and xonotlite.

Examples of the rubber component include, but are not limited to, butadiene, isoprene, and 1,3-pentadiene. These are preferably dispersed in the form of particles in a continuous phase made of a polystyrene-based resin. As a method for adding these rubber components, the rubber components themselves may be added, or resins such as styrene-based elastomers and styrene-butadiene copolymers may be used as a rubber component supply source.
When a rubber component is added, the content of the rubber component may be within the range of the content of the additive, and is preferably 0.3 to 15 parts by mass, more preferably 0.5 to 8 parts by mass, and even more preferably 1 to 5 parts by mass, based on 100 parts by mass of the resin. When the content is 0.3 parts by mass or more, particularly when used as a base resin for a foam described later, the resin has excellent flexibility and elongation, the foam cell membrane is less likely to break during foaming, and a foam having excellent moldability and mechanical strength is easily obtained.

(Production method)
The main body is preferably a foam, and more preferably a foam made from the above-mentioned raw materials.
The method for producing the foam is not particularly limited, but examples thereof include an extrusion foaming method, an injection foaming method, a bead foaming method (in-mold foaming method), a stretch foaming method, and a solvent extraction foaming method.
The extrusion foaming method is a method in which an organic or inorganic foaming agent is forced into a molten resin using an extruder, and the pressure is released at the extruder outlet to obtain a plate-, sheet-, or columnar-shaped foam having a specific cross-sectional shape.
The injection foaming method is a method in which a foamable resin is injection molded and foamed in a mold to obtain a foam having voids.
The bead expansion method (in-mold expansion method) is a method for obtaining a foam by filling a mold with foam beads and heating the beads with steam or the like to expand the beads and simultaneously heat-fuse the beads together.
The stretch foaming method is a method in which additives such as fillers are mixed into a resin in advance, and the resin is stretched to generate microvoids and create a foam.
The solvent extraction foaming method is a method in which an additive that dissolves in a specific solvent is added to a resin, and a molded product is then immersed in the specific solvent to extract the additive and create a foam.

In the case of extrusion foaming, the obtained foam is in the form of a plate, sheet, etc., and processing of this requires a punching step to cut it into the desired shape and a heat lamination step to laminate the cut parts together.
On the other hand, in the case of the bead expansion method, a mold of the desired shape is prepared and expanded beads are filled therein for molding, so that it is easy to mold the foam into a finer or more complex shape.
Even with the injection foaming method, it is possible to mold the foam into a complex shape, but with bead foaming, it is easier to increase the expansion ratio of the foam and it is easier to develop flexibility in addition to heat insulation properties.

The foaming agent is not particularly limited, and any commonly used gas can be used.
Examples of such fluorocarbons include air, carbon dioxide, nitrogen gas, oxygen gas, ammonia gas, hydrogen gas, argon gas, helium gas, and neon gas; trichlorofluoromethane (R11), dichlorodifluoromethane (R12), chlorodifluoromethane (R22), tetrachlorodifluoroethane (R112), dichlorofluoroethane (R141b), chlorodifluoroethane (R142b), difluoroethane (R152a), HFC-245fa, HFC-236ea, HFC-245ca, and HFC-225ca; saturated hydrocarbons such as propane, n-butane, i-butane, n-pentane, i-pentane, and neopentane; dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, furan, and the like. ethers such as fural, 2-methylfuran, tetrahydrofuran, and tetrahydropyran; ketones such as dimethyl ketone, methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, methyl i-butyl ketone, methyl n-amyl ketone, methyl n-hexyl ketone, ethyl n-propyl ketone, and ethyl n-butyl ketone; alcohols such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, and t-butyl alcohol; carboxylates such as methyl formate, ethyl formate, propyl formate, butyl formate, amyl formate, methyl propionate, and ethyl propionate; and chlorinated hydrocarbons such as methyl chloride and ethyl chloride.
These may be used alone or in combination of two or more.

From the viewpoint of flame retardancy, it is preferable that the foaming agent has no or little flammability and flame-supporting properties, and from the viewpoint of gas safety, inorganic gases are more preferable. In addition, inorganic gases are less soluble in resins than organic gases such as hydrocarbons, and gases are easily released from the resin after the foaming process or molding process, so there is also the advantage that the dimensional stability of the foamed body after molding is better over time. Furthermore, when inorganic gases are used, the resin is less likely to be plasticized by the remaining gas, and there is also the advantage that excellent heat resistance is easily exhibited at an earlier stage without going through a process such as aging. Among inorganic gases, carbon dioxide gas is preferable from the viewpoint of solubility in resins and ease of handling. In addition, hydrocarbon-based organic gases are generally highly flammable, and tend to deteriorate in flame retardancy if they remain in the foam.

The foam is preferably produced by the bead expansion method described above and is preferably made of expanded beads.
By using the bead expansion method for molding, the shapeability of the battery holder can be improved.

The bead foam is an expansion molded product produced by the bead expansion method and obtained by fusion molding of resin foam particles.
The expanded resin particles can be obtained, for example, by impregnating the base resin with a foaming agent and expanding the same.

As the foaming agent, any gas that is commonly used can be used.
The foaming agent includes those mentioned above.
These may be used alone or in combination of two or more.
The foaming agent is preferably an inorganic gas from the viewpoint of improving flame retardancy. However, the foaming agent is not limited to the above, and chemical foaming agents may also be used.

The resin foam particles can be produced through a bead expansion process in which the base resin is impregnated with a foaming agent and expanded.
In the bead expansion step, an example of a method for containing (impregnating) the base resin with a blowing agent and expanding the base resin is a method similar to that described in Example 1 of JP-A-4-372630, in which a raw material (pellet-shaped, bead-shaped, etc.) is placed in a pressure-resistant container, the gas in the container is replaced with dry air, and then a blowing agent (gas) is pressed in to impregnate the base resin with the blowing agent (gas), and the pressure is released to transfer the raw material pellets from the pressure container to a foaming furnace, and the raw material pellets are heated with pressurized steam while rotating an agitating blade in the foaming furnace to expand, thereby producing expanded resin particles.

As a method for incorporating a blowing agent into the base resin, a commonly used method can be applied, and examples thereof include a method in which a suspension system such as water is used in an aqueous medium (suspension impregnation), a method using a thermally decomposable blowing agent such as sodium bicarbonate (blowing agent decomposition method), a method in which a gas is brought into an atmosphere of not less than the critical pressure and brought into liquid phase contact with the base resin (liquid phase impregnation), and a method in which a gas is brought into contact with the base resin in a gas phase in a high pressure atmosphere below the critical pressure (gas phase impregnation).
Among these, the method of gas-phase impregnation under a high pressure atmosphere below the critical pressure is particularly preferred.
The gas phase impregnation method has better solubility of gas in resin than suspension impregnation, which is carried out under high temperature conditions, and the content of the blowing agent can be increased. Therefore, it is easy to achieve a high expansion ratio and uniform bubble size. The blowing agent decomposition method is not only carried out under high temperature conditions, but also the amount of gas generated tends to be relatively small because not all of the added thermal decomposition type blowing agent becomes gas. Therefore, gas phase impregnation has the advantage that the content of the blowing agent can be increased more easily. In addition, gas phase impregnation is easier to use equipment such as pressure-resistant equipment and cooling equipment in a more compact manner than liquid phase impregnation, making it easier to keep equipment costs low.

The atmospheric pressure under the gas phase impregnation conditions is preferably 0.5 to 10 MPa, more preferably 0.5 to 5 MPa. The atmospheric temperature is preferably -30 to 100°C, more preferably -20 to 80°C. The impregnation time is preferably 0.1 to 72 hours, more preferably 1 to 24 hours. When the atmospheric pressure, atmospheric temperature, and impregnation time are within the above ranges, gas dissolution into the base resin proceeds more efficiently. In particular, if the atmospheric temperature is low, the amount of impregnation increases but the impregnation speed slows, and if the atmospheric temperature is high, the amount of impregnation decreases but the impregnation speed tends to increase. In order to efficiently proceed with gas dissolution into the base resin, it is preferable to set the above atmospheric temperature in consideration of the balance. In addition, from the viewpoint of improving productivity, the higher the atmospheric temperature, the more preferable it is, and in general, it is easy to increase the impregnation speed and amount of impregnation with amorphous resins.

The amount of the foaming agent impregnated is preferably 0.13 to 20% by mass, more preferably 0.5 to 10% by mass, based on the resin contained in the raw material.
When the amount of the foaming agent (e.g., carbon dioxide gas) is 0.13% by mass or more, a higher expansion ratio is easily achieved, and the variation in the bubble size is reduced, making it easier to suppress the variation in the expansion ratio. When the amount is 20% by mass or less, the bubble size becomes appropriate, making it easier to suppress the decrease in the closed cell ratio due to over-foaming.

The method of foaming the raw material in the bead foaming process is not particularly limited, but examples include a method of suddenly releasing from a high-pressure condition to a low-pressure atmosphere to expand the foaming agent (e.g., gas) dissolved in the resin, and a method of heating with pressurized steam or hot air to expand the foaming agent (e.g., gas) dissolved in the resin. Among these, the method of foaming by heating is particularly preferred. This is because the size of the bubbles inside the resin is more likely to be uniform than the method of suddenly releasing from a high-pressure condition to a low-pressure atmosphere. In addition, this method has the advantage that it is easier to control the foaming ratio, especially the low foaming ratio.
Furthermore, when the resin is suddenly released from a high-pressure condition to a low-pressure atmosphere, foaming starts simultaneously from all points, which makes it difficult to form a skin layer. On the other hand, when foaming by heating, the foaming gas dissipates from the surface layer of the raw material while the resin is heated to the foaming start temperature, making it easy to form a skin layer. Another advantage is that the thickness of the skin layer can be adjusted by adjusting the heating rate and heating temperature, and the faster the heating rate and the higher the heating temperature, the thinner the skin layer tends to be.

When expanding the resin foam particles to the desired expansion ratio, the resin foam particles may be expanded to the desired expansion ratio in one stage, or may be expanded to the desired expansion ratio in multiple stages such as secondary expansion and tertiary expansion. In addition, it is preferable to apply pressure treatment with inorganic gas to preliminary beads (beads that have not been expanded in the final stage) before expansion in each stage.

A foamed molded article (for example, the main body of the present embodiment) can be produced through a foam molding step in which the resin foam particles are fusion molded.
In the foam molding process, for example, resin foam particles are filled into a mold, and the resin foam particles are heated with water vapor or the like to expand the resin foam particles, while at the same time thermally fusing the resin foam particles together to obtain a foam molded body.
In the bead expansion method, a mold of a desired shape is prepared and resin foam particles are filled therein to form a foamed molded article, so that the foamed molded article can be easily formed into a finer or more complex shape. In addition, the bead expansion method can easily increase the expansion ratio of the foamed molded article, and the obtained foamed molded article can easily exhibit flexibility in addition to heat insulation.

The resin foam particles obtained in the bead expansion process may be used in the foam molding process either continuously or at intervals.

Methods for filling the resin foam particles include, for example, the cracking method, in which the mold is slightly open when filling, the compression method, in which compressed beads are filled by applying pressure while the mold is closed, and the compression cracking method, in which compressed beads are filled and then cracked.

Examples of the method for molding the resin foam particles in the foam molding step include a reduced pressure molding method (e.g., JP-B-46-38359) in which a pair of molds for molding the conventional resin foam particles in-mold is used, the resin foam particles are filled into the mold cavity under pressurized atmospheric pressure or reduced pressure, the molds are closed to compress the mold cavity volume by reducing the volume by 0 to 70%, and then a heat medium such as steam is supplied into the mold to heat and fuse the resin foam particles; and a pressure molding method (e.g., JP-B-51-22951) in which the resin foam particles are pressurized in advance with a pressurized gas to increase the pressure inside the resin foam particles, thereby increasing the secondary foamability of the resin foam particles, and the resin foam particles are filled into the mold cavity under atmospheric pressure or reduced pressure while maintaining the secondary foamability, the molds are closed, and then a heat medium such as steam is supplied into the mold to heat and fuse the resin foam particles.
Molding can also be performed by a compression filling molding method (JP-B-46217) in which a cavity pressurized to atmospheric pressure or higher by a compressed gas is filled with resin foam particles pressurized to the said pressure or higher, and then a heat medium such as steam is supplied into the cavity to heat and fuse the resin foam particles. Molding can also be performed by a normal pressure filling molding method (JP-B-649795) in which the secondary expansion power of the resin foam particles is increased under special conditions, the resin foam particles are filled into a pair of mold cavities under atmospheric pressure or reduced pressure, and then a heat medium such as steam is supplied to heat and fuse the resin foam particles, or a combination of the above methods (JP-B-622919).

In the foam molding process, the maximum steam pressure of the pressurized steam inside the mold (inside the foaming furnace) is preferably 30 to 700 kPa·G from the viewpoint of easily obtaining the desired expansion ratio and improving the appearance.

Methods for processing the foam into the desired shape include, but are not limited to, filling a mold with foam particles or molten resin and molding it, cutting with a blade such as a saw blade or a punch blade, cutting with a mill, and bonding multiple foam pieces with heat or a pressure sensitive adhesive or glue.

(shape)
The shape of the main body will now be described.

The shape of the main body may be a cube, a rectangular parallelepiped, an approximately circular cylinder, an approximately polygonal prism, etc.

The main body has a plurality of storage sections each capable of storing a single cylindrical battery. The number of storage sections only needs to be equal to or greater than the number of batteries stored in the battery holder, and the number of storage sections may be the same as the number of stored batteries.
The shapes of the storage sections of the main body may be the same or different.

The main body can surround at least a part of the side surface of the cylindrical battery.
A cross section is created of a battery holder housing a cylindrical battery, passing through a point on the side surface of the cylindrical battery and perpendicular to the direction from the top to the bottom of the cylindrical battery. When the battery holder (e.g., the main body) is on a line that starts at the center of the battery and passes through the point on the side surface of the cylindrical battery, the point is surrounded by the battery holder. Here, the point may be separated from the battery holder or may be in contact. When the point is in contact with the battery holder, the cylindrical battery and the battery holder are in contact at the point. The distance between the point and the battery holder is preferably 30 mm or less, more preferably 20 mm or less, even more preferably 10 mm or less, and particularly preferably 5 mm or less.
The same applies to the top or bottom surface of a cylindrical battery. A cross section is created passing through a point on the top or bottom surface of a cylindrical battery in the direction from the top to the bottom of the cylindrical battery. When the battery holder (e.g., the lid) is present on a line that starts at the center of the battery and passes through the point on the top or bottom surface of the cylindrical battery, the point is surrounded by the battery holder. The distance between the point and the battery holder (e.g., the lid) is preferably 30 mm or less, more preferably 20 mm or less, even more preferably 10 mm or less, and particularly preferably 5 mm or less. When the point and the battery holder are in contact, the cylindrical battery and the battery holder are in contact at the point.

When a cylindrical battery is stored in the battery holder (e.g., the main body), the battery holder may completely or partially surround the side surface of the cylindrical battery. For example, the side surface of the storage section may have a hole having a shape such as a circle or a polygon.
The ratio R1 of the area of the battery surrounded by the battery holder to the total side surface area of the cylindrical battery (100%) is preferably 10% or more, more preferably 20 to 100%, and even more preferably 50 to 100%, from the viewpoints of increasing the contact area to hold the battery firmly and providing cushioning against drops and shocks.
The above numerical range may be the same or different for each storage section. When the area ratio R1 differs for each storage section, it is preferable that the area ratio R1 of all storage sections that store batteries is within the above range. It is also preferable that the average area ratio R1 of all storage sections that store batteries is within the above range.
The above ratio R1 may be a value when a cylindrical battery that is roughly similar in shape to the storage section and accounts for 70 volume % or more (preferably 80 volume % or more, more preferably 90 volume % or more, even more preferably 95 volume % or more, and particularly preferably 99 volume % or more) of the volume of the storage section is stored.

When a cylindrical battery is stored in the battery holder (eg, the main body), the battery holder may be in contact with a portion of the side surface of the cylindrical battery, or may be in contact with the entire side surface.
The ratio R2 of the area of contact between the battery and the battery holder (e.g., the inner surface of the storage section) to the total side surface area of the cylindrical battery (100%) is preferably 10% or more, more preferably 20 to 100%, and even more preferably 50 to 100%, from the standpoint of firmly holding the battery and appropriately exhibiting cushioning properties.
Moreover, from the viewpoint of improving maintainability and ease of assembly by maintaining an appropriate clearance, it may be less than 100%.
The above numerical range may be the same or different for each storage section. When the area ratio R2 differs for each storage section, it is preferable that the area ratio R2 of all storage sections that store batteries is within the above range. It is also preferable that the average area ratio R2 of all storage sections that store batteries is within the above range.
The ratio R2 is preferably equal to or less than the ratio R1, and may be the same as the ratio R1 or may be 5% or more lower than the ratio R1.
The above ratio R2 may be a value when a cylindrical battery that is roughly similar in shape to the storage section and accounts for 70 volume % or more (preferably 80 volume % or more, more preferably 90 volume % or more, even more preferably 95 volume % or more, and particularly preferably 99 volume % or more) of the volume of the storage section is stored.

The cross-sectional shape of the storage section perpendicular to the direction from the top to the bottom of the cylindrical battery to be stored (up-down direction) may be approximately circular, approximately polygonal (e.g., approximately rectangular, approximately pentagonal, approximately hexagonal, etc.), or a shape with part of the outer periphery missing, and it is preferable that the cross-sectional shape of the storage section perpendicular to the up-down direction be approximately similar to the shape of the cylindrical battery to be stored.
The term "approximately similar shapes" refers to shapes that have the same shape but different radii and shapes similar to them. Examples of similar shapes include shapes in which part of the periphery of a cross-sectional shape perpendicular to the vertical direction is changed to a curve, wavy line, broken line, or the like, shapes in which the ratio of the distance from the center of gravity of two corresponding cross-sectional shapes perpendicular to the vertical direction to all points on the periphery is within a range of 0.8 to 1.2 (preferably 0.9 to 1.1) times the average value of the ratio (for example, in the case of an ellipse, the ratio of the distance between the center of gravity of the corresponding two shapes on the periphery and the points on the periphery is calculated at all points on the periphery of the shapes, and the ratio at all points on the periphery is within a range of 0.8 to 1.2, etc.)), and combinations of these shapes, and may be approximately cylindrical. For example, when the battery and the storage section of the battery holder are in contact with each other, an approximately similar shape of a cylindrical battery may be approximately cylindrical. Also, when a hole is made in the storage section of the battery holder, the shape is an approximately circular shape with part of the periphery missing.

The cross-sectional shape of the storage section perpendicular to the vertical direction may be the same or different from the top to the bottom of the stored battery.

From the standpoint of increasing storage efficiency and maintaining appropriate ease of molding, the thickness of the thinnest part between the storage sections of the battery holder (FIGS. 3(B) and 4) is preferably more than 0 mm and not more than 10 mm, more preferably more than 0.5 mm and not more than 10 mm, even more preferably 1.0 to 5.0 mm, and particularly preferably 1.0 to 3.0 mm.
The thinnest portion may be the thinnest location between adjacent storage portions.
The thickness of the thinnest part between each storage section may be the same or different.

From the viewpoints of maintaining appropriate cushioning properties and improving light weight, the density of the main body is preferably 0.5 to 0.01 g/cm ³ , more preferably 0.35 to 0.02 g/cm ³ , and even more preferably 0.35 to 0.05 g/cm ^3. The expansion ratio of the foam is defined as the reciprocal of the density.

(Physical Properties)
The physical properties of the battery holder of this embodiment (for example, the main body and the lid described below) will be described below.

From the standpoint of maintaining appropriate cushioning properties and improving lightweight properties, the ratio of the mass of the battery holder (e.g., the main body) to the total mass of the cylindrical batteries housed in the battery holder (100%) is preferably 25% or less, more preferably 0.5 to 20%, and even more preferably 1.0 to 15%.
Here, the mass of the battery holder may include a top cover and bottom cover if they are separate parts from the main body.

The integral value J75 (FIG. 5) of the compressive strength in the range of strain ratio 0 to 0.75 per ^mm2 area calculated from the compressive strength SS curve created from the relationship between the strain ratio ((initial thickness before compression (mm)-thickness after compression (mm))/initial thickness before compression (mm)) and compressive strength (MPa=N/ ^mm2 ) of the battery holder (e.g., the main body) is preferably 0.1 to 50 N/ ^mm2 , more preferably 0.1 to 30 N/ ^mm2 , and even more preferably 0.5 to 20 N/ ^mm2 , from the viewpoint of maintaining appropriate cushioning properties. J75 can be measured by the method described in the Examples below.
Similarly, the integral value J5 (FIG. 5) of the compressive strength in the range of strain ratio 0 to ^0.05 per mm2 area calculated from the compressive strength SS curve created from the relationship between the strain ratio ((initial thickness before compression (mm) - thickness after compression (mm))/initial thickness before compression (mm)) and the compressive strength (MPa = N/ ^mm2 ) of the battery holder (e.g., the main body) is preferably 0.001 to 1.0 N/ ^mm2 , more preferably 0.01 to 1 N/ ^mm2 , and even more preferably 0.05 to 0.5 N/ ^mm2 , from the viewpoint of maintaining appropriate cushioning properties.
J5 can be measured by the method described in the Examples below.
The above J5 and J75 indicate the amount of energy required to give a 5% and 75% strain per ¹ mm2, respectively. By generating these strains, the energy of the impact is absorbed and the contents are protected.

From the viewpoint of easily achieving appropriate cushioning against a drop impact in the area surrounding the battery holder (e.g., the main body) and the stored cylindrical batteries, in a test in which a battery holder with batteries stored in all storage locations is dropped in a direction perpendicular to the direction in which the batteries are stored, it is preferable that the area surrounded by the cylindrical batteries satisfy the following relationship (1): If the battery holder has the function of protecting the contents from the drop impact, it is easier to adequately protect the contents (batteries, etc.) when transporting the batteries, when assembling a battery pack or module, when using the holder stored in a battery pack, etc.
J5×A1×d1/1000<W×g×h<J75×A1×d1/1000 ・・・(1)
Here, W represents the total mass (kg) of cylindrical batteries housed in the battery holder in the vertical direction of the drop. Specifically, W refers to the total weight of batteries contained in the area obtained by cutting the battery holder in the direction of drop at the largest cross section perpendicular to the drop direction of the battery located at the lowest vertical position in the direction of drop (Figures 3(B) and 4).
g represents the acceleration due to gravity (m/s ² ).
h indicates the drop height (m). Any value can be used for h, but for designs that are generally expected to withstand drop impacts, a value of 1.2 m, for example, may be used. The drop height may be the height from the drop surface to the bottom end of the battery holder in the direction of drop during the drop test.
A1 indicates the area ( ^mm2 ) of the battery that receives the impact of being dropped. A1 may be calculated as "(projected area when light is projected in the direction of the drop onto the battery located at the lowest vertical position in the direction of the drop) x (area ratio R1 of the side surface surrounded by the battery holder to the total area of the side surface of the battery, which is 100%)/100." For example, when the side surface of the battery located at the lowest vertical position in the direction of the drop is 100% surrounded by the battery holder, in the case where the battery is dropped in the radial direction of the cylindrical battery, A1 is calculated as the diameter x height x 100/100 of the cylindrical battery.
d1 indicates the thickness (mm) of the part of the battery holder that receives impact during the drop test. In general, in the case of a drop or collision, the part of the battery holder that receives the most impact is the part between the part that is first struck by the impact object and the contents located directly above it. For example, in the drop test in which a cylindrical battery is dropped in the radial direction, d1 may be the distance (mm) in the drop direction from the battery located at the lowest vertical position in the drop direction to the end of the battery holder that is lowest vertically in the drop direction (Figures 3(B) and 4).

Cushioning properties indicate the degree to which a product can absorb the shock generated when dropped or hit, and reduce the impact on internal parts and products. When considering cushioning properties, two perspectives are required.
The first is whether the energy of the impact can be absorbed. For example, it is important whether the battery holder in this embodiment can absorb the energy generated when it is dropped with the contents (batteries) stored inside. In this case, if the energy of the impact generated when dropped is within the range of the energy that the battery holder can absorb, calculated taking into account the characteristics of the material itself (J5 or J75), the weight of the contents, and the area of the part that receives the impact, J5' (J5 x A1 x d1/1000) to J75' (J75 x A1 x d1/1000), this means that the holder can absorb all of the impact energy by generating a deformation of about 5% to 75% of the initial thickness of the part that receives the impact. If the energy can be absorbed within this range, the battery holder can absorb the energy while appropriately deforming, but if the distortion is too small, the battery holder cannot deform sufficiently when an impact is applied, so the acceleration described below becomes too large, and if the distortion is too large, the battery holder will deform completely when an impact is applied and will not be able to absorb all of the energy.
The second point of view is how to reduce the acceleration of the contents when an impact is actually applied. The force generated on the contents is related to F=ma (F: force, m: mass, a: acceleration) according to Newton's law, that is, the impact force on the contents can be reduced by reducing the acceleration. Even if the energy generated by the collision is within the range of J5' to J75' described above, if the acceleration is large, the force applied will be large and lead to damage to the contents. In general, the allowable G value is determined depending on the contents (G value: a value indicating how many times the acceleration of gravity the acceleration generated on the contents when some kind of impact is received), and the acceleration of the contents when an impact occurs must be smaller than the allowable G value. For this reason, for example, in the holder in this embodiment, it is preferable to design the parts that are easily affected by impacts due to drops, collisions, etc. (such as the outer periphery of the holder and the parts that protect the top/bottom parts of the battery) to an appropriate thickness. Specifically, the time required for shock absorption is calculated from the speed immediately before impact with the ground and the allowable G value of the contents, so if the speed change from the impact speed until the speed becomes completely 0 (stops) is known, the deformation in the time required for shock absorption calculated from the impact speed and the allowable G value can be calculated, and the thickness required for shock absorption can be calculated from that. If it is assumed that the speed change from the impact speed until the speed becomes completely 0 (stops) changes linearly from the impact speed to 0 m/s, it is also possible to roughly calculate the required thickness.

From the viewpoint of improving safety, the flame retardancy of the battery holder (e.g., the main body) is preferably V-2 or higher in the UL94 V flammability test, more preferably V-1 or higher, and even more preferably V-0. In particular, when the batteries are lithium ion secondary batteries and the battery holder is used with them stored therein, lithium ion secondary batteries generally pose a risk of explosion or fire in the event of an abnormality, so it is preferable for the battery holder to be flame retardant.
The flame retardancy can be measured by the method described in the Examples below.

The deflection temperature under load of the battery holder (eg, the main body) is preferably 90° C. or higher, and more preferably 100° C. or higher, from the standpoint of retaining the contents even when exposed to a high-temperature environment.
The deflection temperature under load can be measured by the method described in the Examples section below.

<Cover>
The lid is preferably made of the above-mentioned raw materials, more preferably made of only a foam made of the above-mentioned raw materials, and more preferably made of a bead foam.
The lid preferably comprises a resin.
The lid may be of the same composition as the body or of a different composition.
The lid can be manufactured in a similar manner as the body.

The lid may completely surround or at least partially surround the upper and/or lower surface of at least one of the cylindrical batteries.
The ratio of the area of the cylindrical battery surrounded by the lid to the total area (100%) of the upper or lower surfaces of the battery is preferably 10 to 100%, more preferably 30 to 100%, and even more preferably 50 to 100%, from the viewpoint of maintaining appropriate cushioning against impact.
The lid may surround the entire upper end face and/or the lower end face in the storing direction of the storage section, or may surround at least a part of the upper end face and/or the lower end face. From the viewpoint of maintaining appropriate cushioning against impact, the ratio of the area surrounded by the lid to the total area (100%) of the upper end face or the lower end face is preferably 10% or more, more preferably 30 to 100%, and even more preferably 50 to 100%. "Surrounding" means that when the lid is present on a line drawn parallel to the storing direction from any one point in the storage section, a point on the end face of the storage section that passes through the line is surrounded by the lid.
From the viewpoint of maintaining appropriate shock-absorbing properties, the battery holder may be 100% enclosed (i.e., the entire upper or lower surface of the cylindrical battery is enclosed by the battery holder). The lid may be provided with holes for connecting the battery terminals to external wiring, etc.
The above numerical ranges may be the same or different for each lid of the storage section, and may be the same or different for the upper and lower surfaces.

The lid may be in contact with a part of the upper surface and/or the lower surface of the cylindrical battery, or may be in contact with the entire surface.
The ratio of the area of contact between the battery and the lid to the total area (100%) of the upper or lower surface of the cylindrical battery is preferably 10% or more, more preferably 20 to 100%, and even more preferably 30 to 100%, from the viewpoint of firmly holding the battery and maintaining appropriate cushioning against impact.

From the viewpoint of firmly holding the battery and maintaining appropriate cushioning against impact, the thickness of the lid is preferably more than 0 mm and not more than 50 mm, more preferably 1 to 30 mm, even more preferably 1 to 10 mm, and particularly preferably 1 to 5 mm. For example, it may be more than 0 mm and not more than 5 mm.
The thickness may be the same or different for each lid of the storage section, and may be the same or different for the upper and lower surfaces.

The integral value J75 (FIG. ⁵ ) of the compressive strength in the range of strain ratio 0 to 0.75 per ^mm2 area calculated from the compressive strength SS curve created from the relationship between the strain ratio ((initial thickness before compression (mm) - thickness after compression (mm)) / initial thickness before compression (mm)) and the compressive strength (MPa = N/mm2) of the above lid is preferably 0.1 to 50 N/ ^mm2 , more preferably 0.1 to 30 N/ ^mm2 , and even more preferably 0.5 to 20 N/ ^mm2 , from the viewpoint of maintaining appropriate cushioning properties.
It is preferable that the energy J75 satisfies the above range at the portion where the lid contacts the upper surface and/or the lower surface of the battery.
Similarly, the integral value J5 (FIG. ⁵ ) of the compressive strength in the range of strain ratio 0 to 0.05 per mm2 area calculated from the compressive strength SS curve created from the relationship between the strain ratio ((initial thickness before compression (mm)-thickness after compression (mm))/initial thickness before compression (mm)) and the compressive strength (MPa=N/ ^mm2 ) of the lid is preferably 0.001 to 1.0 N/ ^mm2 , more preferably 0.01 to 1 N/ ^mm2 , and even more preferably 0.05 to 0.5 N/ ^mm2 from the viewpoint of maintaining appropriate cushioning properties. It is preferable that the energy J5 satisfies the above range at the contact portion between the lid and the upper and/or lower surface of the battery.

The main body and the lid may be connected or may be independent.
For example, during battery manufacturing, only the main body may be provided to facilitate easy insertion and removal of the battery from the battery holder, and the independent lid may be placed over the battery after manufacturing.

<Batteries>
The cylindrical battery stored in the battery holder of this embodiment may be substantially cylindrical.
The number of batteries stored in the battery holder of this embodiment may be between 2 and 1000. In particular, when considering the impact of a drop, the number of batteries aligned vertically may be between 2 and 50.
The battery is preferably a secondary battery, and may be a lithium ion battery.
The cylindrical battery is preferably approximately similar in shape to the shape of the storage section of the battery holder of this embodiment. The cylindrical battery preferably has a volume of 70% or more, more preferably 80% or more, even more preferably 90% or more, still more preferably 95% or more, and particularly preferably 99% or more, of the 100% volume of the storage section of the battery holder of this embodiment. An example of 100% by volume is when R2 is 100%.

<Applications>
The battery holder of this embodiment can store multiple cylindrical batteries and can be used, for example, as a holder used from battery production through to transportation, such as for aging, charging, and other steps in battery assembly, as a battery positioning holder for maintaining the position of each battery during battery assembly and use, etc.
The battery of this embodiment can be used in applications where at least a portion of the side surface of the cylindrical battery is surrounded by a battery holder, so that the ratio R1 of the area of the side surface surrounded by the battery holder to the total area of the cylindrical battery's side surface is 10% or more.Furthermore, the battery can be used in applications where the ratio R2 of the area of the part where the battery side surface and the battery holder contact each other to the total area of the cylindrical battery's side surface (100%) is 10% or more.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

The measurement and evaluation methods used in the examples and comparative examples are described below.

(1) Density and Expansion Ratio of Battery Holder Samples measuring 30 mm square and 10 mm thick were prepared in the same manner as in the battery holders obtained in the Examples and Comparative Examples, and the mass [g] of each sample was measured and divided by the sample volume [ ^cm3 ] to calculate the density (g/ ^cm3 ).

(2) Flame Retardancy of Battery Holder The battery holders obtained in the examples and comparative examples were subjected to a test in accordance with the UL-94 vertical method (20 mm vertical flame test) of the US UL standard to evaluate their flame retardancy.
The details of the measurement method are shown below.
The same material as in each Example and Comparative Example was prepared, and five test pieces with a length of 125 mm, width of 13 mm, and foam thickness of 10.0 mm were prepared and used. The test pieces were attached vertically to a clamp and exposed to a 20 mm flame for 10 seconds twice, and the burning behavior was judged as V-0, V-1, or V-2. When measuring the unfoamed material described in Comparative Example 2, the thickness of the sample was changed to 1.5 mm and the measurement was performed.
V-0: The duration of flaming combustion was within 10 seconds for both the first and second tests, the total of the duration of flaming combustion and the flameless combustion time for the second test was within 30 seconds, the total of the flaming combustion times for the five test pieces was within 50 seconds, no samples burned up to the position of the fixing clamps, and no cotton was ignited by burning falling debris.
V-1: The duration of flaming combustion was within 30 seconds for both the first and second tests, the sum of the duration of flaming combustion and the flameless combustion time for the second test was within 60 seconds, the total flaming combustion time for the five test pieces was within 250 seconds, no samples burned up to the position of the fixing clamps, and no cotton was ignited by burning falling debris.
V-2: The duration of flaming combustion for both the first and second tests was within 30 seconds, the sum of the duration of flaming combustion and the flameless combustion time for the second test was within 60 seconds, the total flaming combustion time for the five test pieces was within 250 seconds, no samples burned up to the position of the fixing clamps, and cotton was ignited by burning falling debris.
Anything not falling under any of the above V-0, V-1, or V-2 was deemed non-compliant (x).

(3) Battery holder deflection temperature under load (HDT)
The same materials as the battery holders in each of the Examples and Comparative Examples described below were prepared, and the deflection temperature under load was measured in accordance with ISO 75-1 and 75-2 as described below.
First, a sample of 80 mm long x 13 mm wide x 10 mm thick was prepared using the same material as the battery holder of each of the examples and comparative examples described below. The obtained sample was set in a HDT tester machine test (model 3M-2) manufactured by Toyo Seiki Seisakusho Co., Ltd. so that the distance between the supports was 64 mm. A pressing tool was set on the center part of the set sample, and the sample was immersed in an oil bath with a force of 0.45 MPa applied. Thereafter, the temperature was increased at a rate of 120 ° C./hour, and the sample temperature at the time when the pressing tool moved until the bending threshold value of 0.34 mm was reached was taken as the load deflection temperature (° C.). The unfoamed material described in Comparative Example 2 was measured in accordance with ASTM D648.

(4) Measurement of the compressive strength of the battery holder First, a sample of 20 mm wide x 200 mm long x 30 mm thick was prepared using the same material as the battery holder in each of the examples and comparative examples described below. Next, a compression test was performed at a strain rate of 1 (/s) in a room temperature environment using an autograph (AG-X plus series AG-50kNPlus, manufactured by Shimadzu Corporation). In addition, it is preferable to set the strain rate during the compression strength measurement to a strain rate as close as possible to the actual impact rate in considering the impact properties described later, but it may be used as a reference value even if the strain rate is significantly different.
A graph was prepared of the strain ratio ((initial thickness before compression (mm) - thickness after compression (mm))/initial thickness before compression (30 mm)) versus compressive strength (MPa), and a compressive strength SS curve was prepared.
The integral value J75 (N/mm ² ) in the strain ratio range of 0 to 0.75 and the integral value J5 (N/mm ² ) in the strain ratio range of 0 to 0.05 were calculated.

The raw materials used in the examples and comparative examples are described below.

(1) Foam 5 (foaming ratio 5.0 cm ³ /g)
60% by mass of S201A (manufactured by Asahi Kasei Corporation) as a polyphenylene ether resin (PPE), 15% by mass of bisphenol A bis(diphenyl phosphate) (BBP) as a non-halogen flame retardant, 10% by mass of high impact polystyrene resin (HIPS) with a rubber concentration of 6% by mass, and 15% by mass of GP685 (manufactured by PS Japan Co., Ltd.) as a general-purpose polystyrene resin (PS) were added, and the mixture was heated, melted, kneaded in an extruder and then extruded to prepare base resin pellets.
In accordance with the method described in Example 1 of JP-A-4-372630, the base resin pellets were placed in a pressure vessel, the gas in the vessel was replaced with dry air, and then carbon dioxide (gas) was injected as a foaming agent. The base resin pellets were impregnated with carbon dioxide over a period of 3 hours under conditions of a pressure of 3.0 MPa and a temperature of 10° C., and the base resin pellets were immediately transported after being removed from the pressure vessel. The base resin pellets were foamed in a foaming furnace with pressurized steam of up to 260 kPa·G while rotating an agitating blade at 77 rpm, to obtain foamed particles.
In the foaming step, the time from removal from the pressure vessel to the start of heating with pressurized steam was 10 seconds. The content of hydrocarbon gas in the foamed beads was measured by gas chromatography immediately after foaming, and was below the detection limit (0.01% by mass).
The expanded beads were then placed in a container and pressurized by introducing pressurized air (pressure was increased to 0.4 MPa over 4 hours, and then maintained at 0.4 MPa for 16 hours). The resulting mixture was filled into an in-mold molding die having a steam hole, heated with steam to expand and fuse the expanded beads to each other, cooled, and removed from the molding die to obtain a foam 5.0 (expansion ratio 5.0 ^cm3 /g) made of expanded beads.

(2) Foam 10 (foaming ratio 10 cm ³ /g)
Foam 10 (expansion ratio 10 cm ³ /g) made of foamed beads was obtained in the same manner as Foam 5, except that in the heating step after impregnation with carbon dioxide, the pressure of the pressurized steam was set to 330 kPa·G.

(3) Foam 5H
A foam 5H (expansion ratio 5.0 cm ³ /g) made of expanded beads was obtained in the same manner as in Example 2, except that the base resin pellets were changed as follows.
Base resin pellets:
60% by mass of GP685 (manufactured by PS Japan Co., Ltd.) as a polystyrene-based resin (PS) and 40% by mass of S201A (manufactured by Asahi Kasei Corporation) as a polyphenylene ether-based resin (PPE) were heated, melted, kneaded in an extruder, and then extruded to prepare base resin pellets.

(4) Foam EE15
The internal pressure of the expanded beads in the production process of the secondary expanded beads was adjusted by adjusting the expansion temperature with reference to the contents of Example 3 of JP-A-4-372630 so that the expansion ratio of the final foam would be 15.0 ^cm3 /g, and the obtained secondary expanded beads were used for molding with reference to the production method of Foam 2.5 to obtain Foam EE15 (expansion ratio 15 ^cm3 /g). The content of hydrocarbon gas in the obtained expanded beads (secondary expanded beads) was measured immediately after foaming, and was below the detection limit (0.01% by mass).

(5) Foam XE15
With reference to JP 2006-077218 A, a foam was produced in the following manner.
First, low-density polyethylene (PE) (density 922 kg/m ³ , MI=7.0 g/10 min) was fed at a rate of 900 kg/hr into the feed region of a screw-type extruder having a barrel inner diameter of 150 mm, together with 1.2 parts by mass of talc powder (particle size 8.0 μm) as a bubble nucleating agent and 0.8 parts by mass of a gas permeability regulator (stearic acid monoglyceride) per 100 parts by mass of the resin. The barrel temperature of the extruder was adjusted to 190-210° C., and a foaming agent consisting of 100% by mass of n-butane was injected from a foaming agent injection port attached to the tip of the extruder in an amount of 3 parts by mass per 100 parts by mass of the resin, and mixed with the molten resin composition to obtain a foamable molten mixture.
This foamable molten mixture was cooled to 108°C by a cooling device attached to the outlet of the extruder, and then continuously extruded and foamed through an orifice plate having an average thickness of about 4.0 mm and an opening shape of about 226 mm in width into an atmosphere at room temperature and atmospheric pressure. The resin foam was molded while adjusting the take-up speed to obtain a plate-shaped foam with a thickness of 52 mm, a width of 560 mm, a length of 1000 mm, and an expansion ratio of 15 ( ^cm3 /g). The content of hydrocarbon gas contained in this resin foam was 2.4% by mass. After storing for 3 months in a 40°C environment and confirming that the content of hydrocarbon gas was below the detection limit (0.01% by mass), foam XE15 (expansion ratio 15 ( ^cm3 /g)) was obtained. Note that the obtained foam was a plate-shaped extruded foam, so it was used to manufacture a battery holder by performing secondary processing such as cutting and bonding.

(6) Foam EP15 (foaming ratio 15 ^cm3 /g)
A foam was molded in the same manner as for Foam 5 using Eperan PP (manufactured by Kaneka Corporation, expansion ratio 15 cm ³ /g) to obtain Foam EP15 (expansion ratio 15 cm ³ /g).

(7) PC (density 1.19 g/cm ³ )
A battery holder was made by injection molding using polycarbonate (LEXAN EXL9330 manufactured by Savic Corporation).

(8) PA2.8 foam (foaming ratio 2.8 ^cm3 /g)
Nylon 666 (nylon 66/6) (trade name: Novamid 2430A, manufactured by DSM Co., Ltd.) was used as a polyamide resin, copper iodide and potassium iodide were used as heat stabilizers, and talc was used as a nucleating agent. The mixture was mixed at 0.8 parts by mass of talc, 0.03 parts by mass of copper iodide, and 0.29 parts by mass of potassium iodide per 100 parts by mass of polyamide resin, melt-kneaded under heating conditions in a twin-screw extruder, extruded into a strand shape, cooled in a cold water tank, and cut to produce pellets for polyamide resin expanded particles in the form of pellets. The average pellet length of the obtained pellets for polyamide resin expanded particles was 1300 μm, and the average pellet diameter was 900 μm.
The obtained pellets for polyamide-based resin expanded particles were immersed in water at 50°C for 1 hour, and then dehydrated in a commercially available washing machine to obtain pellets for water-absorbing polyamide-based resin expanded particles in the form of pellets containing 14% by mass of water.
The obtained water-containing pellets for water-absorbing polyamide-based resin expanded particles were placed in a pressure cooker at 10°C, and carbon dioxide gas of 4 MPa was blown in and absorbed for 12 hours, so that the pellets for water-absorbing polyamide-based resin expanded particles contained 1.6 mass% of carbon dioxide gas as a foaming agent. The foaming agent-impregnated pellets for polyamide-based resin expanded particles containing carbon dioxide gas were then transferred to a foaming device, and 175°C air was blown in for 20 seconds to obtain polyamide-based resin expanded particles.
The obtained expanded polyamide resin particles were placed in a water-permeable nonwoven bag and immersed in a thermostatic water bath heated to 50° C. for 30 minutes to obtain expanded hydrous polyamide resin particles. The expanded hydrous polyamide resin particles had a water absorption rate of 12%.
The thus obtained hydrous polyamide-based resin expanded particles were placed in an autoclave, and compressed air was introduced into the autoclave over one hour until the pressure therein reached 0.95 MPa. Thereafter, the pressure was maintained at 0.95 MPa and the temperature at 70°C for 24 hours, thereby subjecting the polyamide-based resin expanded particles to a pressure treatment.
The pressurized polyamide resin foamed beads were filled into an internal molding die having a steam hole, heated with steam to expand and fuse the foamed beads to each other, and then cooled and removed from the molding die to obtain a PA2.8 foamed bead (expansion ratio 2.8 ^cm3 /g).

Example 1
A molded product having the shape shown in FIG. 6 was produced from the materials shown in Table 1, and used as a battery holder. That is, a battery holder was produced having 28 cylindrical storage sections each having a diameter of 46 mm extending in the height direction of the battery holder in a main body having a length of 411 mm, a width of 260 mm, and a height of 80 mm. The thickness of the thinnest part between the storage sections was 9 mm. The lithium ion batteries shown in Table 1 were prepared and stored in the obtained battery holder. The characteristics of the holder and the battery were also measured, and the results are shown in Table 1. Cylindrical batteries having a diameter of 46 mm, a height of 80 mm, and a weight of 358 g were stored in all storage sections (FIG. 3(A)).
Furthermore, a test was conducted in which the battery holder was dropped from a height of 1.2 m in the longitudinal direction with batteries stored therein, as shown in Fig. 3(B), and the shock-absorbing properties were examined with a focus on the number and shape of the battery holder and batteries present in the direction of the drop (Table 1). The potential energy (W x g x h) of the holder containing the batteries immediately before the drop was greater than J5' and smaller than J75'. In the above drop test, the direction in which the batteries were stored was the horizontal direction, and the direction of drop was the direction perpendicular to the direction in which the batteries were stored (Fig. 3(B)). Note that Fig. 3(B) is a schematic diagram for explaining the drop test, and therefore has a different number of storage sections from Fig. 6, which shows the battery holder of this embodiment. In Fig. 3(B), when the battery located at the bottommost vertically in the direction of drop is projected with light in the direction of drop, one side 7 of the projection surface of the battery is equal to one side of the largest cross section with the largest area among the cross sections perpendicular to the direction of drop of the battery located at the bottommost vertically in the direction of drop.
The drop test results showed that the battery holder was able to absorb the impact energy generated by the drop impact by appropriately deforming. The energy that the battery holder could absorb was not so small that it would be destroyed, and there was no risk of the battery holder deforming too little when a drop impact occurred, resulting in too great an impact force on the batteries. Therefore, it was determined that the battery holder had good energy absorption properties.

(Examples 2 to 17)
Battery holders were manufactured in the same manner as in Example 1, except for the changes noted in Table 1, the change in the shape of the battery holder as shown in Figures 7 to 17 as noted in Table 1, and the change in the size of the batteries to be stored.
Moreover, the same batteries as in Example 1 were placed in all the storage compartments, and the same drop test was carried out.
In Examples 9 to 11, because holes were provided that penetrated the battery holder in the longitudinal or lateral direction, the ratio R1 was less than 100%.
In all of Examples 2 to 17, the impact energy generated by the drop impact was absorbed by the battery holder through appropriate deformation. The energy that the battery holder could absorb was not too small to cause the battery holder to be destroyed, nor was the deformation of the battery holder too small when a drop impact occurred to result in an excessively large impact force on the batteries. Therefore, energy absorption was determined to be good.

(Comparative Examples 1 to 2)
A battery holder was manufactured in the same manner as in Example 1 except for the changes shown in Table 1.
Moreover, the same batteries as in Example 1 were placed in all the storage compartments, and the same drop test was carried out.
In addition, since a hole was provided penetrating the ionization holder in the longitudinal or lateral direction, the ratio R1 was 5%.
In Comparative Examples 1 and 2, the proportion of the area of the battery side surface surrounded by the battery holder was small, so the impact energy generated by the drop impact could not be absorbed and the battery holder was destroyed, and therefore energy absorption was judged to be poor.On the other hand, in Comparative Example 2, the holder was made of an unfoamed resin, and almost no deformation due to compression during the drop test occurred, resulting in an extremely large impact force on the battery.
In addition, since Comparative Example 2 was made of unfoamed resin, the compressive strength could not be measured.

The dimensions of each battery holder in Figures 7 to 18 are as follows:
Figure 7: A rectangular parallelepiped with a length of 361 mm, a width of 260 mm, and a height of 80 mm. The storage section has a diameter of 46 mm and a height of 80 mm.
Figure 8: A rectangular parallelepiped with a length of 777 mm, a width of 260 mm, and a height of 80 mm. The storage section has a diameter of 46 mm and a height of 80 mm.
Figure 9: A rectangular parallelepiped with a length of 1092 mm, a width of 254 mm, and a height of 80 mm. The storage section has a diameter of 46 mm and a height of 80 mm.
Figure 10: A rectangular parallelepiped with a length of 304 mm, a width of 214 mm, and a height of 80 mm. The storage section has a diameter of 46 mm and a height of 80 mm.
Figure 11: A rectangular parallelepiped with a length of 1128 mm, a width of 114 mm, and a height of 65 mm. The storage section has a diameter of 18 mm and a height of 65 mm.
Figure 12: A rectangular parallelepiped with a length of 588 mm, a width of 114 mm, and a height of 65 mm. The storage section has a diameter of 18 mm and a height of 65 mm.
Figure 13: A rectangular parallelepiped with a length of 375 mm, a width of 120 mm, and a height of 65 mm. The storage section has a diameter of 18 mm and a height of 65 mm.
Figure 14: A holder consisting of two rectangular parallelepipeds, 777 mm long, 260 mm short, and 4 mm high. The upper and lower end faces of the stored batteries are aligned with the upper and lower end faces of each component (Figure 14). The storage section is 46 mm in diameter and 80 mm high.
Figure 15: A holder consisting of two rectangular parallelepipeds, 777 mm long, 260 mm short, and 16 mm high. The upper and lower end faces of the stored batteries are aligned with the upper and lower end faces of each component (Figure 15). The storage section is 46 mm in diameter and 80 mm high.
Figure 16: A holder consisting of two rectangular parallelepipeds, 777 mm long, 260 mm short, and 32 mm high. The upper and lower end faces of the stored batteries are aligned with the upper and lower end faces of each component (Figure 16). The storage section is 46 mm in diameter and 80 mm high.
Figure 17: A rectangular parallelepiped with a length of 238 mm, a width of 168 mm, and a height of 80 mm. The storage section has a diameter of 46 mm and a height of 80 mm.
Figure 18: A holder consisting of two rectangular parallelepipeds, 777 mm long, 260 mm short, and 2 mm high. The upper and lower end faces of the stored batteries are aligned with the upper and lower end faces of each component (Figure 18). The storage section is 46 mm in diameter and 80 mm high.

1 Battery holder (main unit)
2 Cylindrical battery 3 Storage compartment 4 Top cover 5 Battery holder (main body and top cover)
6 Area when the battery holder is cut in the falling direction at the largest cross section that has the largest area among cross sections perpendicular to the falling direction of the battery located at the lowest vertical position in the falling direction 7 Side d1 of the projection surface of the battery located at the lowest vertical position in the falling direction when the battery is projected with light in the falling direction d2 Distance in the falling direction from the battery located at the lowest vertical position in the falling direction to the edge of the battery holder J5 Thickness of the thinnest part between the storage sections J75 Integrated value of compressive strength in the strain ratio range of 0 to 0.05 calculated from the compressive strength SS curve J75 Integrated value of compressive strength in the strain ratio range of 0 to 0.75 calculated from the compressive strength SS curve

Claims (14)

1. A battery holder for storing a plurality of cylindrical batteries, comprising:
Made from raw materials including resin,
at least a portion of the side surface of the cylindrical battery is surrounded by the battery holder, and a ratio R1 of the area of the side surface surrounded by the battery holder to the total area of the cylindrical battery's side surface (100%) is 10% or greater;
A battery holder characterized by: The battery holder according to claim 1, wherein the shape of the portion of the battery holder that houses the cylindrical battery is approximately similar to the shape of the side of the cylindrical battery. The battery holder according to claim 1 or 2, in which the ratio R2 of the area of the portion where the side surface of the cylindrical battery contacts the battery holder to the total area (100%) of the side surface of the cylindrical battery is 10% or more. 3. The battery holder according to claim 1, wherein the integral value J75 of compressive strength within a strain ratio range of 0 to 0.75 per ^mm2 area calculated from a compressive strength SS curve is 0.1 to 50 N/ ^mm2 . 3. The battery holder of claim 1 or 2, wherein the battery holder contains multiple cylindrical batteries, and in a test in which the battery holder is dropped in a direction perpendicular to the direction in which the batteries are contained, satisfies the relationship of the following formula (1):
J5×A1×d1/1000<W×g×h<J75×A1×d1/1000 ・・・(1)
(In the above formula (1), J5 is the integral value (N/mm ² ) of the compressive strength of the battery holder when the strain ratio per mm ² ranges from 0 to 0.05 as calculated from the compressive strength SS curve; J75 is the integral value (N/mm ² ) of the compressive strength of the battery holder when the strain ratio per mm ² ranges from 0 to 0.75 as calculated from the compressive strength SS curve; A1 is "(projected area of the battery when the battery located at the lowest point in the vertical direction is projected with light in the direction of fall) x (ratio of the area of the side surface of the battery surrounded by the battery holder to 100% of the total area of the side surfaces of the battery R1)/100" (mm ² ); d1 is the distance in the direction of fall from the battery located at the lowest point in the vertical direction to the end of the battery holder (mm); W is the total weight (kg) of batteries included in the area obtained by cutting the battery holder in the direction of fall at the largest cross section that has the largest area among the cross sections perpendicular to the fall direction of the battery located at the lowest point in the vertical direction; g is the acceleration of gravity (m/s ² ); and h is the fall height (m).) The battery holder according to claim 1 or 2, wherein the thickness of the thinnest part between the battery-storing portions of the battery holder is greater than 0 mm and less than or equal to 10 mm. The battery holder according to claim 1 or 2, wherein the flame retardancy of the battery holder is V-2 or higher. The battery holder according to claim 1 or 2, wherein the deflection temperature under load of the battery holder is 90°C or higher. The battery holder according to claim 1 or 2, which is made of foam. The battery holder according to claim 1 or 2, which is made of bead foam. Further, the battery housing includes a cover that surrounds at least a portion of an upper end surface and/or a lower end surface of the portion that houses the at least one battery,
3. The battery holder according to claim 1, wherein the lid is made of a foam containing a resin. The battery holder of claim 11, wherein the foam is a bead foam. 12. The battery holder according to claim 11, wherein the lid has an integral value J75 of compressive strength within a strain ratio range of 0 to 0.75 per ^mm2 area calculated from a compressive strength SS curve, which is 0.1 to 50 N/ ^mm2 . The battery holder according to claim 11, wherein the thickness of the lid is greater than 0 mm and less than or equal to 5 mm.

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