Rubber composition and battery

Abstract

To provide a rubber composition capable of extinguishing fire in a short time with respect to ignition caused by rapid temperature rise of a battery cell, etc. and excellent in adhesiveness, workability, and ability to conform to an object being protected.　The present invention provides a rubber composition that contains 50-2000 mass parts of a metal hydroxide per 100 mass parts of a matrix polymer. The matrix polymer contains a liquid rubber and a solid elastomer, and the mass ratio of the liquid rubber and the solid elastomer is 95:5 to 50:50.　

Description

Rubber composition and battery

[0001] The present invention relates to a rubber composition and a battery, and more particularly to a rubber composition that is a putty-like composition and is mainly used for batteries.

[0002] In various types of batteries, such as lithium batteries, internal short circuits or the like can cause thermal runaway in battery cells, resulting in fires, smoke, and other problems. To mitigate the problems caused by such thermal runaway, attempts have been made to use protective materials, such as fireproofing materials or heat insulating layers, around battery cells. Such protective materials are expected to make it difficult for heat from high-temperature battery cells to propagate to other battery cells and the housing that houses the battery cells.

[0003] For example, Patent Document 1 discloses a fire-resistant resin composition containing a heat-absorbing agent having a thermal decomposition starting temperature of 800° C. or less and an endothermic amount of 300 J / g or more, and a resin.

[0004] Patent Publication No. 2019-143139

[0005] The fire-resistant resin composition of Patent Document 1 is, for example, a fire-resistant resin composition that is made by blending a large amount of aluminum hydroxide into EVA resin, and is capable of quickly extinguishing a fire that occurs in a battery of a mobile phone, etc. However, blending a large amount of inorganic compound into the resin impairs flexibility and adhesiveness, and the resin is unable to conform to the cylindrical battery cell, leaving gaps that could allow a fire to break out to the outside.

[0006] Therefore, the present invention provides a rubber composition that can extinguish fires caused by sudden temperature rises in battery cells in a short period of time, and that has excellent adhesion, workability, and conformability to objects to be protected.

[0007] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the above problems can be solved by using a composition with a specific blend, which has led to the completion of the present invention.

[0008] That is, the present invention provides the following inventions. [1] A rubber composition comprising 50 to 2000 parts by mass of a metal hydroxide relative to 100 parts by mass of a matrix polymer, wherein the matrix polymer comprises a liquid rubber and a solid elastomer, and the mass ratio of the liquid rubber to the solid elastomer is 95:5 to 50:50. [2] The rubber composition according to [1], wherein the metal hydroxide comprises aluminum hydroxide. [3] The rubber composition according to [1] or [2], which is in a putty form. [4] The rubber composition according to any one of [1] to [3], which is used in a battery. [5] A battery comprising a member constituted by the rubber composition according to any one of [1] to [4].

[0009] According to the present invention, it is possible to provide a rubber composition that can extinguish a fire caused by a sudden temperature rise in a battery in a short time, and that has excellent adhesion, workability, and conformability to an object to be protected. Such a rubber composition has an appropriate softness and can be used, for example, as a putty-like protective material that can conform to the shape of a cylindrical battery cell.

[0010] Fig. 1A is a schematic diagram showing how a rubber composition is attached to the surface of a cylindrical battery cell. Fig. 1B is a schematic diagram showing the state in which the rubber composition is attached to the surface of a cylindrical battery cell. Fig. 2 is a schematic diagram showing how an adhesion test is performed.

[0011] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail, but the present invention is not limited thereto and various modifications are possible within the scope of the present invention. Such a rubber composition is a composition with excellent deformability and can be used as a putty that can be easily adapted to a shape. In other words, the composition can also be provided as a putty-like fire-resistant composition.

[0012] The rubber composition of this embodiment contains a matrix polymer and a metal hydroxide. The matrix polymer contains a liquid rubber and a solid elastomer, and the mass ratio of the liquid rubber to the solid elastomer is 95:5 to 50:50. Each component will be described below.

[0013] 1. Matrix Polymer The matrix polymer contains a liquid rubber and a solid elastomer, and the mass ratio of the liquid rubber to the solid elastomer is 95:5 to 50:50. This mass ratio is preferably 93:7 to 60:40, and more preferably 90:10 to 70:30. If the proportion of liquid rubber is too high, workability will be poor, and if the proportion of liquid rubber is too low, tracking will be poor. If the total mass ratio of the liquid rubber and the solid elastomer is 100, the mass ratio of the solid elastomer may be, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50, or may be within a range between any two of the values ​​exemplified here. The mass ratio of the liquid rubber is calculated by subtracting the mass ratio of the solid elastomer from 100.

[0014] The rubber composition contains, for example, 5 to 70% by mass, preferably 6 to 25% by mass, and more preferably 7 to 15% by mass of the matrix polymer, based on 100% by mass of the rubber composition.

[0015] <Liquid Rubber> In the present invention, the liquid rubber may be any rubber that is fluid at room temperature (25°C), such as liquid polyisoprene, liquid polybutadiene, liquid polychloroprene, liquid polybutene, liquid butyl rubber, etc. However, it is not necessarily limited to one type, and two or more types may be mixed. The liquid rubber is preferably liquid polyisoprene or liquid polybutene, and more preferably liquid polyisoprene.

[0016] <Solid Elastomer> In the present invention, the solid elastomer may be any elastomer that is solid at room temperature (25°C), and examples thereof include natural rubber, isoprene rubber, butadiene rubber, 1,2-polybutadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, chlorinated butyl rubber, chlorinated polyethylene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM), ethylene-vinyl acetate rubber, chloroprene rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, acrylonitrile-butadiene rubber (NBR), crosslinkable rubber such as reclaimed rubber, fluororubber, urethane rubber, and styrene-based thermoplastic elastomers. However, the solid elastomer is not necessarily limited to one type, and two or more types may be mixed.

[0017] Styrenic thermoplastic elastomers are thermoplastic elastomers containing monomer units derived from vinyl aromatic hydrocarbons. Thermoplastic elastomers soften and become fluid when heated, and are distinguishable from rubbers that do not possess such properties. Styrenic thermoplastic elastomers are preferably block copolymers composed of a polymer block primarily composed of vinyl aromatic hydrocarbons and a polymer block primarily composed of conjugated dienes. Examples of vinyl aromatic hydrocarbons include styrene, p-methylstyrene, α-methylstyrene, vinylxylene, monochlorostyrene, dichlorostyrene, and monobromostyrene, which may be used alone or in combination of two or more. Examples of conjugated dienes include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene, which may be used alone or in combination of two or more.

[0018] Specific examples of styrene-based thermoplastic elastomers include styrene-butadiene-styrene (SBS) copolymer, styrene-isoprene-styrene (SIS) copolymer, styrene-ethylene-butylene-styrene (SEBS) copolymer, styrene-isoprene-hydrogenated styrene-isoprene-styrene (SEPS) copolymer, styrene-ethylene-propylene (SEP) copolymer, styrene-ethylene-propylene-styrene (SEPS) copolymer, and styrene-ethylene-ethylene-propylene-styrene (SEEPS) copolymer.

[0019] The solid elastomer is preferably rubber (rubber-like), and among these, butyl rubber, EPDM, or NBR is preferred, with butyl rubber being particularly preferred.

[0020] The matrix polymer may be composed only of liquid rubber and solid elastomer, or may contain other polymers. Examples of other polymers include resins that are neither liquid rubber nor solid elastomers (such as polyolefins and polystyrene). The matrix polymer contains 50% by mass or more of the liquid rubber and solid elastomer in total, preferably 80% by mass or more, more preferably 95% by mass, and even more preferably (substantially) 100% by mass of the matrix polymer.

[0021] 2. Metal hydroxide Examples of metal hydroxides include aluminum hydroxide, calcium hydroxide, magnesium hydroxide, etc., but they are not necessarily limited to one type and may be a mixture of two or more types. The metal hydroxide is preferably aluminum hydroxide or calcium hydroxide, and particularly preferably aluminum hydroxide.

[0022] The content of the metal hydroxide is 50 to 2000 parts by mass, preferably 250 to 2000 parts by mass, more preferably 250 to 1600 parts by mass, and even more preferably 480 to 1200 parts by mass, relative to 100 parts by mass of the matrix polymer. When the content of the metal hydroxide is 50 parts by mass or more, good fire extinguishing properties are achieved. When the content of the metal hydroxide is 2000 parts by mass or less, good flexibility, conformability, and adhesiveness are achieved. The content of the metal hydroxide is, for example, 50, 100, 150, 200, 250, 300, 350, 400, 450, 480, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, or 2000 parts by mass per 100 parts by mass of the matrix polymer, and may be within a range between any two of the numerical values ​​exemplified here.

[0023] 3. Other Components In the present embodiment, inorganic compounds other than metal hydroxides used in ordinary rubber compounds, fibrous organic compounds, plasticizers (softeners), antioxidants, processing aids, lubricants, flame retardants, tackifiers, and the like may be used in combination within a range that does not impair the effects of the rubber composition.

[0024] <Inorganic Compounds Other Than Metal Hydroxides> Examples of inorganic compounds other than metal hydroxides include metal oxides such as alumina, aluminosilicate, zinc oxide, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, antimony oxide, and ferrites; smectite clays such as sepiolite, bentonite, montmorillonite, and hectorite, fibrous clays such as palygorskite, clay minerals such as sericite, illite, glauconite, chlorite, talc, zeolite, beidellite, nontronite, saponite, hectorite, sauconite, stevensite, cristopalite, smectite, kaolin, and hydrotalcite; metal carbonates such as basic magnesium carbonate, calcium carbonate, magnesium carbonate, zinc carbonate, strontium carbonate, and barium carbonate; glass fibers (E glass fiber, C glass fiber, S glass fiber, Examples of inorganic fibrous compounds include D-glass fiber, rock wool, ceramic fibers (silica-alumina fiber, alumina fiber, silica fiber), zirconia fiber, carbon fiber, bulk alkaline earth silicate fiber, gypsum fiber, carbon fiber, metal fiber, slag fiber, and basalt fiber; calcium salts such as calcium sulfate and calcium silicate, glass beads, silica-based balun, aluminum nitride, boron nitride, silicon nitride, carbon black, graphite, carbon balun, charcoal powder, various metal powders, potassium titanate, magnesium sulfate, lead zirconate titanate, aluminum borate, molybdenum sulfide, silicon carbide, zinc borate, various magnetic powders, fly ash, inorganic hollow fillers, pearlite, obsidian, perlite, colophonite, diatomaceous earth, dewatered sludge, boron, sodium tetraborate hydrate (borax), silica, vermiculite, thermally expandable graphite, and inorganic phosphate compounds. These inorganic compounds may be used alone or in combination of two or more.

[0025] The content of the inorganic compound other than the metal hydroxide is, for example, 100 parts by mass or less, preferably 0.1 to 100 parts by mass, relative to 100 parts by mass of the matrix polymer. Specific examples of the content of the inorganic compound other than the metal hydroxide relative to 100 parts by mass of the matrix polymer include 0, 0.1, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0026] <Thermal Expandable Graphite> The rubber composition of the present invention may contain thermal expandable graphite. When thermal expandable graphite is contained, the thermal expandable graphite expands upon heating to form large-capacity voids and functions as a flame retardant, thereby suppressing the spread of fire.

[0027] Thermally expandable graphite refers to graphite that has the property of thermally expanding by 100 times or more when exposed to a temperature equal to or higher than the expansion starting temperature (about 200° C.) under normal pressure.

[0028] Such graphite is not particularly limited, but examples thereof include crystalline compounds obtained by surface-treating graphite powder such as natural graphite or pyrolytic graphite with an inorganic acid such as sulfuric acid or nitric acid and a strong oxidizing agent such as concentrated nitric acid or permanganate, while maintaining a graphite layer structure. Note that graphite powder such as natural graphite or pyrolytic graphite may be subjected to a deoxidation treatment or further a neutralization treatment.

[0029] The content of the thermally expandable graphite relative to the mass parts of the matrix polymer is, for example, 300 parts by mass or less, preferably 1 to 300 parts by mass, more preferably 20 to 200 parts by mass, and even more preferably 30 to 150 parts by mass. When the content of the thermally expandable graphite is within the above range, it becomes easier to form large-volume voids in the rubber composition, thereby improving flame retardancy.

[0030] <Inorganic Phosphate Compound> The inorganic phosphate compound refers to a compound containing at least one of a phosphate compound, a phosphite compound, a hypophosphite compound, a metaphosphate compound, a pyrophosphate compound, and a polyphosphate compound.

[0031] The phosphate compound is not particularly limited, but examples thereof include monoaluminum phosphate, monosodium phosphate, monopotassium phosphate, monocalcium phosphate, monozinc phosphate, dialuminum phosphate, disodium phosphate, dipotassium phosphate, dicalcium phosphate, dizinc phosphate, trialuminum phosphate, trisodium phosphate, tripotassium phosphate, tricalcium phosphate, trizinc phosphate, trimagnesium phosphate, monoammonium phosphate, diammonium phosphate, tricalcium phosphate, and aluminum phosphate.

[0032] Examples of the phosphite compounds include aluminum phosphite, aluminum hydrogen phosphite, sodium phosphite, potassium phosphite, calcium phosphite, and zinc phosphite.

[0033] Examples of hypophosphite compounds include aluminum hypophosphite, sodium hypophosphite, potassium hypophosphite, calcium hypophosphite, and zinc hypophosphite.

[0034] Examples of metaphosphate compounds include aluminum metaphosphate, sodium metaphosphate, potassium metaphosphate, calcium metaphosphate, zinc metaphosphate, and sodium hexametaphosphate.

[0035] Examples of pyrophosphate compounds include sodium pyrophosphate.

[0036] Examples of polyphosphate compounds include ammonium polyphosphate, sodium polyphosphate, and melamine-modified ammonium polyphosphate.

[0037] Among the inorganic phosphate compounds, ammonium hydrogen phosphite is preferred. The content of the inorganic phosphate compound is, for example, 200 parts by mass or less, preferably 3 to 200 parts by mass, more preferably 5 to 150 parts by mass, and even more preferably 10 to 100 parts by mass, relative to the parts by mass of the matrix polymer. When the content of the inorganic phosphate compound is within the above range, the rubber composition exposed to high temperatures and carbonized does not lose its shape, and shape stability is improved.

[0038] <Fibrous Organic Compound> The shape of the fibrous organic compound may be fibrous, and examples of the cross-sectional shape of the fiber include circular, elliptical, and polygonal. When the average fiber length of the fibrous organic compound is L and the average diameter is D, L / D is, for example, more than 10, preferably 50 or more, and more preferably 100 or more. The upper limit is not particularly specified, but is, for example, 10,000. The average diameter of the fibrous organic compound is, for example, 1 to 100 μm, preferably 2 to 50 μm, and more preferably 5 to 20 μm. The average fiber length of the fibrous organic compound is, for example, preferably 0.5 to 10 mm. This value may be, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0 mm, or may be within a range between any two of the values ​​exemplified here.

[0039] Examples of fibrous organic compounds include meta-aramid fibers, para-aramid fibers, amide fibers, cellulose fibers (e.g., pulp fibers), polyparaphenylenebenzbisoxazole fibers, polyarylate fibers, polyester fibers, acrylic fibers, acrylonitrile fibers, rayon, silk, cotton, hemp, and wool.

[0040] The average fiber length and average diameter of the fibrous organic compound are determined by measuring the fiber length and diameter of a sufficiently large number of fibrous organic compounds, i.e., 20 or more, and averaging the measured values.

[0041] The fiber length and diameter of the fibrous organic compound can be measured using, for example, a field emission scanning electron microscope (FE-SEM).

[0042] The content of the fibrous organic compound is, for example, 30 parts by mass or less, preferably 1 to 30 parts by mass, more preferably 3 to 24 parts by mass, and even more preferably 6 to 17 parts by mass, per 100 parts by mass of the matrix polymer. The content of the fibrous organic compound is, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 parts by mass, per 100 parts by mass of the matrix polymer, and may be within a range between any two of the values ​​exemplified here. When the content of the fibrous compound is within this range, the balance between the cohesion and adhesion of the rubber composition is improved.

[0043] <Plasticizer (Softener)> The content of the plasticizer is, for example, 16 parts by mass or less, preferably 0.5 to 15 parts by mass, and more preferably 1 to 10 parts by mass, relative to 100 parts by mass of the matrix polymer. The content of the plasticizer is, for example, 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 parts by mass, relative to 100 parts by mass of the matrix polymer, and may be within a range between any two of the numerical values ​​exemplified here.

[0044] <Antiaging Agent> The content of the antioxidant is, for example, 10 parts by mass or less, preferably less than 2.5 parts by mass, and more preferably 0.5 to 2 parts by mass, relative to 100 parts by mass of the matrix polymer. The content of the antioxidant is, for example, 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, or 10.0 parts by mass, relative to 100 parts by mass of the matrix polymer, and may be within a range between any two of the numerical values ​​exemplified here.

[0045] The rubber composition of the present embodiment can be prepared by kneading the above components using a known kneading device such as a Banbury mixer, a kneader mixer, or a two-roll mill, and then molding the mixture using a conventionally known molding method such as press molding, roll molding, extrusion molding, or calendar molding.

[0046] <Other Embodiments> A battery according to another embodiment of the present invention includes a member made of the rubber composition. The battery typically has at least one battery cell 3, and the putty-like rubber composition (putty-like composition) is attached to the battery as a member 1 such as a protective material or fireproof material ( FIG. 1 ). The rubber composition is typically attached to the surface of the battery cell. The battery may have one battery cell or two or more battery cells.

[0047] In addition, examples of battery cells include secondary batteries such as lithium ion batteries, lithium ion polymer batteries, nickel-metal hydride batteries, lithium-sulfur batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, sodium-sulfur batteries, lead-acid batteries, and air batteries, but are not limited to these.

[0048] Batteries are used in, but not limited to, small electronic devices such as mobile phones and smart phones, laptops, automobiles, power tools, and the like.

[0049] <Laminate> As described above, the rubber composition of the present invention may contain thermally expandable graphite. In one embodiment of the present invention, the rubber composition may be provided as a laminate in which layers of fire-resistant sheets or the like containing thermally expandable graphite are laminated.

[0050] The laminate may include, for example, a first layer and a second layer provided on the first layer directly or via another layer. The first layer is made of the rubber composition.

[0051] The second layer is composed of a thermally expandable composition containing thermally expandable graphite. The thermally expandable composition may further contain a matrix polymer in addition to the thermally expandable graphite, and may further contain an inorganic compound.

[0052] The matrix polymer contained in the thermally expandable composition of the second layer is not particularly limited, but examples thereof include rubber, elastomer, thermoplastic resin, thermosetting resin, etc. The matrix polymer may be the same as or different from the matrix polymer contained in the rubber composition.

[0053] The inorganic compound contained in the thermally expandable composition of the second layer is not particularly limited, but can be selected from the same options as the inorganic compounds (metal hydroxides or inorganic compounds other than metal hydroxides) that can be contained in the rubber composition of the first layer, for example.

[0054] The inorganic compound may be the same as or different from the inorganic compound contained in the rubber composition of the first layer.

[0055] The thermally expandable graphite contained in the thermally expandable composition of the second layer can be selected from the same options as the thermally expandable graphite that can be contained in the rubber composition of the first layer.

[0056] The content of the thermally expandable graphite in the thermally expandable composition of the second layer is preferably 1 to 300 parts by mass, more preferably 20 to 200 parts by mass, and even more preferably 30 to 150 parts by mass, relative to the mass of the matrix polymer.

[0057] In one example, the first layer may not contain thermally expandable graphite and the second layer may contain thermally expandable graphite, and in another example, both the first layer and the second layer may contain thermally expandable graphite.

[0058] The thickness of the second layer is not particularly limited, but is preferably 0.1 to 20 mm, for example.

[0059] The thickness of the laminate is not particularly limited, but is preferably 0.2 to 40 mm, for example.

[0060] The thickness ratio of the first layer to the second layer is not particularly limited, but is preferably, for example, first layer:second layer=1:200 (for example, 0.1 mm:20 mm) to 200:1 (for example, 20 mm:0.1 mm).

[0061] The laminate may be used as a component for a battery, and a battery according to an embodiment may include the laminate.

[0062] The present invention will be specifically explained below with reference to examples and comparative examples, but these examples do not limit the present invention.

[0063] 1. Preparation of Rubber Compositions The components shown in the formulations in Tables 1 to 3 were kneaded for 10 minutes at 80°C using a 3-liter kneader mixer to obtain rubber compositions for the Examples and Comparative Examples, which were then used as test specimens.

[0064]

[0065]

[0066]

[0067] Details of the components in the table are as follows: (1) Matrix polymer <Liquid rubber> Liquid polyisoprene: "LIR-30" manufactured by Kuraray Co., Ltd., molecular weight 28,000, Tg: -63°C, viscosity 70 Pa·s (38°C) Liquid polybutadiene: "LBR-302" manufactured by Kuraray Co., Ltd., molecular weight 5,500, Tg: -85°C, viscosity 0.6 Pa·s (38°C) Liquid polybutene: "HV-100" manufactured by JX Nippon Oil & Energy Corporation, molecular weight 980, kinematic viscosity 9,500 mm ２ / s (40 ° C)

[0068] <Solid elastomers> Butyl rubber: "Butyl 268" manufactured by JSR Corporation, rubber-like, softness (21°C) 25 [1 / 10 mm] EPDM: "EP51" manufactured by JSR Corporation, rubber-like, softness (21°C) 17 [1 / 10 mm] NBR: "Nipol DN401" manufactured by Zeon Corporation, rubber-like, softness (21°C) 13 [1 / 10 mm]

[0069] (2) Metal hydroxides Aluminum hydroxide (Al hydroxide): "C-301N" manufactured by Sumitomo Chemical Co., Ltd. Calcium hydroxide (Ca hydroxide): "Slaked lime" manufactured by Maruai Lime Industry Co., Ltd. Magnesium hydroxide (Mg hydroxide): "KISMA5A" manufactured by Kyowa Chemical Substances Co., Ltd.

[0070] (3) Other components <Other resins> EVA: "Evaflex EV460" manufactured by Mitsui DuPont Polychemicals Co., Ltd., resinous, softness (21°C) 7 [1 / 10 mm] <Inorganic compounds other than metal hydroxides> Calcium carbonate (Ca carbonate): "TA-044" manufactured by Chichibu Lime Industry Co., Ltd.

[0071] 2. Evaluation The rubber compositions of each Example and Comparative Example were subjected to the following measurements and evaluations. The results are shown in Tables 1 to 3. As shown in the tables, all Examples were good in terms of conformability, adhesion, workability (non-adhesion), and digestibility. On the other hand, all Comparative Examples were not good in at least one of these evaluation items.

[0072] <Conformability (Softness)> The softness of the test piece was measured in accordance with JIS A5752 at a load of 150 g and a temperature of 21°C. A specified cone was perpendicularly penetrated into the test piece, and the penetration depth was measured to the nearest 0.1 mm. Then, based on the penetration depth, the processability was evaluated according to the following criteria: ◎: 60 [1 / 10 mm] or more ○: 50 [1 / 10 mm] or more but less than 60 [1 / 10 mm] △: 40 [1 / 10 mm] or more but less than 50 [1 / 10 mm] ×: Less than 40 [1 / 10 mm]

[0073] <Adhesion> As shown in Figure 2, a 3g spherical test piece 5 was sandwiched between two aluminum plates 7 specified in JIS H4000 (A1050) and compressed to a thickness of 5mm. After 1 minute, the test piece was peeled vertically at a peeling speed of 300mm / min, and the adhesion was measured based on the peak strength at the time of peeling. The adhesion was then evaluated according to the following criteria: ◎: 3 [N] or more ○: 2 [N] or more but less than 3 [N] △: 1 [N] or more but less than 2 [N] ×: less than 1 [N]

[0074] <Workability (Non-adhesion)> After measuring the mass of the latex rubber glove, the subject put on the latex rubber glove and gripped a 100 g spherical test piece (putty) 10 times. The weight of the deposit on the glove was then measured, and the weight of the deposit was calculated using the following formula. Then, based on the weight of the deposit, non-adhesion was evaluated according to the following evaluation criteria: Weight of deposit [g] = (Weight of glove after gripping the putty 10 times) - (Original weight of glove) [Evaluation criteria] ◎: Weight of deposit is less than 0.5 [g]. ○: Weight of deposit is 0.5 [g] or more but less than 1.0 [g]. △: Weight of deposit is 1.0 [g] or more but less than 1.5 [g]. ×: Weight of deposit is 1.5 [g] or more.

[0075] <Fire extinguishing properties> A test specimen was prepared by placing the test piece around a laminated lithium ion battery used in smartphones so that it completely covered the battery. The test specimen was then placed on a hot plate set at 300°C, and the time from the release of fire to the extinguishing of the fire was evaluated. A shorter fire extinguishing time indicates better fire extinguishing performance. ◎: Fire extinguishing time is less than 3 seconds; ○: Fire extinguishing time is 3 to 5 seconds; △: Fire extinguishing time is 5 to 10 seconds; ×: Fire extinguishing time is 10 seconds or more.

Claims

1. A rubber composition comprising 50 to 2000 parts by mass of a metal hydroxide per 100 parts by mass of a matrix polymer, wherein the matrix polymer comprises a liquid rubber and a solid elastomer, and the mass ratio of the liquid rubber to the solid elastomer is 95:5 to 50:

50.

2. The rubber composition according to claim 1, wherein said metal hydroxide comprises aluminum hydroxide.

3. The rubber composition according to claim 1, wherein the content of the inorganic compound other than the metal hydroxide is 50 parts by mass or less per 100 parts by mass of the matrix polymer.

4. The rubber composition of claim 1, wherein said solid elastomer is rubbery.

5. The rubber composition according to claim 1, which is in the form of a putty.

6. The rubber composition according to any one of claims 1 to 5, which is used in a battery.

7. A battery comprising a member made of the rubber composition according to any one of claims 1 to 5.

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