Silicone rubber composition for battery sealing material, and battery sealing material

Abstract

To provide a silicone rubber composition for a battery sealing material that has enhanced flame retardancy relative to a conventional art.SOLUTION: A battery silicone rubber composition in an aspect of the present invention contains a flame retardant silicone rubber compound and a fibrous flame retardant, the fibrous flame retardant being contained in an amount of 5 to 60 pts.wt. assuming that the flame retardant silicone rubber compound is contained in an amount of 100 pts.wt., and the flame retardant silicone rubber compound being rated as V-0 or higher in accordance with UL94 standard.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a silicone rubber composition for a battery sealant and to a battery sealant. [Background technology]

[0002] BACKGROUND ART In the past, compositions have been proposed in which various additives have been added to silicone rubber in order to impart industrially desirable physical properties (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 48-080656 [Patent Document 2] Japanese Patent Application Publication No. 57-209980 [Patent Document 3] Japanese Patent Application Publication No. 60-182199 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when silicone rubber is used as a sealing material for a battery, it is preferable that the silicone rubber be flame-retardant. The inventors' investigations have revealed that there is still room for improvement in the flame-retardant properties of existing flame-retardant silicone rubber compounds.

[0005] An object of one aspect of the present invention is to provide a silicone rubber composition for sealing materials that has improved flame retardancy compared to conventional compositions. [Means for solving the problem]

[0006] In order to solve the above problems, a silicone rubber composition according to one aspect of the present invention comprises: The flame-retardant silicone rubber compound and the fiber-based flame retardant are included, When the content of the flame-retardant silicone rubber compound is 100 parts by weight, the content of the fiber-based flame retardant is 5 to 60 parts by weight, The flame-retardant silicone rubber compound is rated V-0 or higher according to the UL94 standard. [Effects of the Invention]

[0007] According to one aspect of the present invention, there is provided a silicone rubber composition for sealing materials that has improved flame retardancy compared to conventional compositions. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a battery using a sealing material according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and various modifications are possible within the scope of the description. Embodiments in which the technical means disclosed in different embodiments are appropriately combined are also included in the technical scope of the present invention.

[0010] In this specification, "A to B" representing a numerical range means "A or more and B or less."

[0011] 1. Silicone rubber composition for sealing materials The silicone rubber composition for sealing materials according to one embodiment of the present invention contains a flame-retardant silicone rubber compound and a fibrous flame retardant. Each component will be described below.

[0012] [1.1. Flame-retardant silicone rubber compounds] Flame-retardant silicone rubber compounds are compositions that have been given flame retardancy by blending various additives into silicone rubber. Flame-retardant silicone rubber compounds have a flame retardancy rating of V-0 or higher according to the UL94 standard.

[0013] The UL94 standard is a standard for evaluating the flame retardancy of plastic products and is widely adopted worldwide. The UL94 standard grades, in descending order of flame retardancy, are 5VA, 5VB, V-0, V-1, V-2, and HB. Therefore, the flame-retardant silicone rubber compound is rated 5VA, 5VB, or V-0 under the UL94 standard. In one embodiment, the flame-retardant silicone rubber compound is rated V-0 under the UL94 standard. The test method for the UL94 standard is well known to those skilled in the art, so a description thereof will be omitted.

[0014] The flame-retardant silicone rubber compound contains a silicone rubber. In one embodiment, the silicone rubber is an organopolysiloxane resin. In the organopolysiloxane resin, the proportion of units having an organopolysiloxane structure among all units contained in the main chain is preferably 50% or more, more preferably 70% or more, and even more preferably 90% or more. Specific examples of silicone rubber include methylsilicone rubber, vinylmethylsilicone rubber, phenylmethylsilicone rubber, and fluorinated silicone rubber. These silicone rubbers may be contained alone or in combination of two or more. In one embodiment, the flame-retardant silicone rubber compound contains vinylmethylsilicone rubber. Examples of additives contained in the flame-retardant silicone rubber compound include platinum, platinum compounds, iron oxide, triazole compounds, and aluminum hydroxide. These additives may be contained alone or in combination of two or more. Many flame-retardant silicone rubber compounds are commercially available, and many related patent documents exist. Therefore, detailed explanation of the composition of the flame-retardant silicone rubber compound will be omitted.

[0015] Examples of commercially available flame-retardant silicone rubber compounds include SILASTIC™ SH502U, SH502U A / B, and SH1447 UA (all manufactured by Dow-Toray Industries, Inc.); KE-5620W-U, KE-5620BL-U, KE-5612E-U, KE-3494, KE-3490, KE-3467, KE-4890, KE-40RTV, KE-1831, KE-1867, KE-1891, KE-1204-LTV, KE-1292, KE-1800, and KE-1802 (all manufactured by Shin-Etsu Chemical Co., Ltd.); and ELASTOSIL® LR 3011 / 50 FR, LR 3001 / 55 FR, LR 3001 / 60 FR, and LR 3001 / 60 FR. 3170 / 40 (all manufactured by Asahi Kasei Wacker Silicone Co., Ltd.); TSE2186U, TSE2183U, TSE2187U, TSE2184U, TCM5406U, XE20-A7016 (all manufactured by Momentive Performance Materials Japan LLC).

[0016] Examples of patent documents disclosing flame-retardant silicone rubber compounds include JP-A-2004-149693, JP-A-2006-182911, and JP-A-2009-144024.

[0017] [1.2. Fiber-based flame retardants] The fibrous flame retardant refers to a flame retardant in a fibrous form. In this specification, the term "fibrous form" refers to a shape having an aspect ratio (length / diameter) of 3 or more.

[0018] The inventors have discovered that a silicone rubber composition combining a flame-retardant silicone rubber compound with a fiber-based flame retardant exhibits improved flame retardancy compared to the flame-retardant silicone rubber compound itself. However, the improved flame retardancy was not observed when flame retardants other than fiber-based flame retardants (such as phosphorus-based flame retardants or particulate inorganic flame retardants) were added (see the examples of this application for details). In other words, it can be said that the effects of the present invention were achieved by selecting a fiber-based flame retardant from among the various types of flame retardants.

[0019] The lower limit of the average fiber length of the fibrous flame retardant is preferably 50 μm or more, more preferably 70 μm or more, and even more preferably 100 μm or more. The upper limit of the average fiber length of the fibrous flame retardant is preferably 1500 μm or less, more preferably 1000 μm or less, and even more preferably 800 μm or less. The lower limit of the average diameter of the fibrous flame retardant is preferably 0.05 μm or more, more preferably 0.1 μm or more, even more preferably 0.15 μm or more, and particularly preferably 0.2 μm or more. The upper limit of the average diameter of the fibrous flame retardant is preferably 10.0 μm or less, more preferably 5.0 μm or less, even more preferably 3.0 μm or less, and particularly preferably 1.0 μm or less. The lower limit of the aspect ratio is preferably 5 or more, more preferably 50 or more, even more preferably 100 or more, and particularly preferably 150 or more. The upper limit of the aspect ratio is preferably 5000 or less, more preferably 4000 or less, even more preferably 1000 or less, particularly preferably 500 or less, and even more preferably 250 or less. The lower limit of the shot content of the fibrous flame retardant may be 0.1 wt% or more, 0.01 wt% or more, or substantially 0 wt% or more, based on the weight of the fibrous flame retardant. The upper limit of the shot content of the fibrous flame retardant is preferably 5 wt% or less, more preferably 1 wt% or less, and even more preferably 0.5 wt% or less, based on the weight of the fibrous flame retardant. Here, shot refers to non-fibrous particles that were not fiberized during the manufacturing process of the fibrous flame retardant.

[0020] Examples of fiber-based flame retardants include man-made mineral fibers, natural mineral fibers, and synthetic organic fibers. Examples of man-made mineral fibers include rock wool, stone wool, slag wool, mineral wool, glass wool, and mineral glass wool. Examples of natural mineral fibers include wollastonite and potassium titanate fiber. Examples of synthetic organic fibers include aramid fiber. Among these, man-made mineral fibers are preferred. Among man-made mineral fibers, rock wool is preferred. In one embodiment, the fiber-based flame retardant is an inorganic substance. In one embodiment, the fiber-based flame retardant is not asbestos.

[0021] [1.3. Other Ingredients] The silicone rubber composition for a seal according to one embodiment of the present invention may contain components other than those mentioned above, such as a curing agent.

[0022] The curing agent is a component that imparts rubber elasticity to the silicone rubber composition. Those skilled in the art can select an appropriate curing agent depending on the reaction mechanism for imparting rubber elasticity. Examples of reaction mechanisms involving curing agents include crosslinking reactions, condensation reactions, and addition reactions.

[0023] To impart rubber elasticity through a crosslinking reaction, organic peroxides can be used, such as benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, cumyl-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, and di-t-butyl peroxide.

[0024] When rubber elasticity is imparted by a condensation reaction, a silicon-containing crosslinking agent and a curing catalyst can be used. Examples of the silicon-containing crosslinking agent include alkoxysilane, acetoxysilane, and cyclic siloxane. Examples of the curing catalyst include metal carboxylates and organotin compounds.

[0025] When rubber elasticity is imparted by an addition reaction, organohydrogenpolysiloxane and a platinum catalyst can be used. Organohydrogenpolysiloxane is a polyorganosiloxane in which an average of two or more hydrogen atoms are bonded to silicon atoms per molecule.

[0026] The silicone rubber composition may contain an oil. Among oils, silicone oil is preferred, and modified silicone oil is more preferred. Silicone oil refers to an oil whose main component is polyorganosiloxane. Modified silicone oil refers to a silicone oil in which some of the methyl groups contained in dimethylsilicone oil are substituted with other functional groups. Examples of modified silicone oils include amino-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, carbinol-modified silicone oil, (meth)acrylic-modified silicone oil, mercapto-modified silicone oil, phenol-modified silicone oil, polyether-modified silicone oil, methylstyryl-modified silicone oil, alkyl-modified silicone oil, higher fatty acid ester-modified silicone oil, higher alkoxy-modified silicone oil, fluorine-modified silicone oil, and aralkyl-modified silicone oil. Modified silicone oils include non-reactive modified silicone oils and reactive modified silicone oils. Among these, non-reactive modified silicone oils are preferred.

[0027] The silicone rubber composition may contain various additives known in the art, such as reinforcing fillers (silica, diatomaceous earth, quartz powder, mica, titanium oxide, etc.), extending fillers (diatomaceous earth, quartz powder, mica, clay, glass beads, aluminum oxide, etc.), heat resistance improvers (carbon black, red iron oxide, alkali metal oxides, alkaline earth metal oxides, etc.), and pigments.

[0028] [1.4. Composition of Silicone Rubber Composition] Based on the total weight of the silicone rubber composition, the lower limit of the content of the flame-retardant silicone rubber compound is preferably 50% by weight or more, more preferably 55% by weight or more, and the upper limit of the content of the flame-retardant silicone rubber compound may be, for example, 98% by weight or less.

[0029] Based on the total weight of the silicone rubber composition, the lower limit of the silicone rubber polymer content is preferably 10% by weight or more, more preferably 15% by weight or more, and even more preferably 18% by weight or more. The upper limit of the silicone rubber polymer content may be, for example, 98% by weight or less.

[0030] When the silicone rubber composition contains a rubber component other than silicone rubber, the proportion of silicone rubber in the total rubber component is preferably 50% by weight or more, more preferably 70% by weight or more, and even more preferably 90% by weight or more. In one embodiment, the silicone rubber composition does not contain any rubber component other than silicone rubber. Examples of rubber components other than silicone rubber include fluororubber (FKM), natural rubber (NR), styrene-butadiene rubber (SBR), isoprene rubber (IR), butadiene rubber (BR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), butyl rubber (IIR), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), urethane rubber (U), ethylene-acrylic rubber (AEM), and acrylic rubber (ACM).

[0031] The lower limit of the content of the fiber-based flame retardant in the silicone rubber composition is 5 parts by weight or more, preferably 15 parts by weight or more, and more preferably 20 parts by weight or more, based on 100 parts by weight of the flame-retardant silicone rubber compound. When the lower limit of the content is within the above range, the silicone rubber composition tends to have sufficient flame retardancy. The upper limit of the content of the fiber-based flame retardant in the silicone rubber composition is 60 parts by weight or less, preferably 50 parts by weight or less, more preferably 45 parts by weight or less, and even more preferably 40 parts by weight or less, based on 100 parts by weight of the flame-retardant silicone rubber compound. When the upper limit of the content is within the above range, the silicone rubber composition tends to have a softness suitable for use as a sealing material.

[0032] The lower limit of the oil content in the silicone rubber composition is preferably 0.1 wt% or more, more preferably 0.3 wt% or more, and even more preferably 0.5 wt% or more, based on the total weight of the silicone rubber composition. If the oil content is less than 0.1 wt%, processability may be reduced. The upper limit of the oil content in the silicone rubber composition is preferably 15 wt% or less, more preferably 10 wt% or less, and even more preferably 5 wt% or less, based on the total weight of the silicone rubber composition. If the oil content exceeds 15 wt%, the silicone rubber composition may become excessively soft or bleeding may occur.

[0033] The amounts of other components can be appropriately determined by those skilled in the art according to common technical knowledge. For example, the content of the curing agent may be 0.2 to 5.0 parts by weight, assuming the content of the flame-retardant silicone rubber compound is 100 parts by weight.

[0034] [1.5. Physical Properties of Silicone Rubber Composition] The Shore A hardness of the silicone rubber composition is preferably 85 or less, and more preferably 80 or less. If the Shore A hardness is within the above range, it can be said that the composition has a softness suitable for use as a sealing material. In this specification, the Shore A hardness is measured using a Type A durometer based on JIS K6253. For more specific examples of the measurement method, see the examples of the present application. The Shore A hardness of the silicone rubber composition is measured using the silicone rubber composition after curing in its normal state (a state in which no heat resistance test or flame test has been performed).

[0035] The compression set of the silicone rubber composition after the heat resistance test is preferably 50 or less, more preferably 30 or less. If the compression set after the heat resistance test is within the above range, it can be said that the composition has sufficient elasticity even after exposure to high temperatures. In this specification, the compression set after the heat resistance test is measured based on JIS K6262. For more specific examples of the measurement method, see the examples of the present application. Note that the compression set of the silicone rubber composition after the heat resistance test is measured for the silicone rubber composition after curing.

[0036] The silicone rubber composition has improved flame retardancy compared to the flame-retardant silicone rubber compound alone. In this specification, "improved flame retardancy" means that one or more (preferably two or more, more preferably all) of the following three conditions are met. For the method of conducting the flame retardancy test, see the examples in this application. Smoke emergence time is delayed. The time of flame outbreak is delayed. - Flame duration is reduced.

[0037] [2. Sealing materials and batteries] A sealing material according to one embodiment of the present invention comprises the silicone rubber composition for sealing material described above. In this specification, the term "sealing material" refers to a molded product that is interposed between two or more components. The two or more components may be components whose relative positions change or may be components that are relatively stationary. The sealing material has the function of sealing, for example, the movement of a fluid (gas, liquid, or a mixture thereof).

[0038] The use of the sealing material is not particularly limited. Since the sealing material according to one embodiment of the present invention has improved flame retardancy, it is preferably used in products that require flame retardancy. Examples of such products include batteries, vehicles, housing construction materials, home appliances, and mobile terminals.

[0039] An example of application of a sealing material according to one embodiment of the present invention to a battery will be described below with reference to Fig. 1. The battery 10 includes a sealing material 1, a cell 2, a heat insulating material 3, and a container 4. The battery 10 is configured to extract power from two or more cells 2 (12 cells 2 in Fig. 1). Note that Fig. 1 does not show components for extracting power from the cells 2. A specific example of the battery 10 is a non-aqueous electrolyte secondary battery (such as a lithium ion secondary battery).

[0040] The sealing material 1 is a sealing material according to one embodiment of the present invention. The cell 2 is a power generation element in which a positive electrode, a negative electrode, a separator, an electrolyte, etc. are packaged. The heat insulating material 3 is a member that prevents heat generated by the cell 2 from being transmitted. The container 4 is a member that houses the sealing material 1, the cell 2, and the heat insulating material 3.

[0041] The interior of the container 4 is divided into two or more compartments by the insulating material 3. In FIG. 1, the container 4 is divided into four compartments: compartment A, compartment B, compartment C, and compartment D. If there are two or more cells 2, they are arranged in two or more of the two or more compartments. In FIG. 1, cells 2 are arranged in all four compartments A to D, but there may be a compartment in which no cell 2 is arranged. The sealing material 1 is arranged so as to close the gap between the insulating material 3 and the container 4.

[0042] For example, if cell 2 arranged in compartment A malfunctions and catches fire, sealing material 1 and insulating material 3 prevent the fire from spreading to compartment B. Since sealing material 1 is a sealing material according to one embodiment of the present invention, it has improved flame retardancy compared to conventional sealing materials. Therefore, battery 10 has improved safety compared to conventional batteries.

[0043] 3. Silicone rubber composition for sealing material and method for producing sealing material There are no particular limitations on the method for producing the silicone rubber composition for sealing material according to one embodiment of the present invention. For example, the silicone rubber composition for sealing material can be produced by kneading the components described in Section [1]. A kneader can be used to knead the components. Examples of kneaders include open rolls, kneaders, planetarium mixers, Banbury mixers, and extruders. The kneading temperature may be 25 to 200°C. The kneading time may be 1 minute to 1 hour.

[0044] The method for producing the sealing material according to one embodiment of the present invention is not particularly limited. For example, the sealing material can be produced by molding and curing the silicone rubber composition for sealing material described above. Examples of molding methods include injection molding, transfer molding, casting molding, compression molding, press processing, and extrusion molding. The curing temperature may be 25 to 200°C. The curing time may be 10 seconds to 120 minutes.

[0045] The order of curing and molding is not particularly limited. The silicone rubber composition may be molded after curing, the silicone rubber composition may be molded during the curing reaction, or the molded article may be cured after molding.

[0046] The cured molded article may be further subjected to secondary curing. The secondary curing temperature may be 25 to 250° C. The secondary curing time may be 30 minutes to 4 hours.

[0047] [4. Summary] The present invention includes the following configurations. <1> The flame-retardant silicone rubber compound and the fiber-based flame retardant are included, When the content of the flame-retardant silicone rubber compound is 100 parts by weight, the content of the fiber-based flame retardant is 5 to 60 parts by weight, The flame-retardant silicone rubber compound is a silicone rubber composition for sealing materials that meets the UL94 standard of V-0 or higher. <2> The fiber-based flame retardant is characterized in that it contains one or more selected from the group consisting of artificial mineral fibers, natural mineral fibers, and synthetic organic fibers. <1> 2. The silicone rubber composition for sealing materials according to claim 1. <3> The fiber-based flame retardant contains the artificial mineral fiber, The man-made mineral fiber includes rock wool. <2> 2. The silicone rubber composition for sealing materials according to claim 1. <4> The fiber-based flame retardant has a fiber length of 50 to 500 μm and a shot content of 5 wt % or less. <1> ~ <3> 1. The silicone rubber composition for sealing materials according to claim 1, <5> The content of the flame-retardant silicone rubber compound in the silicone rubber composition for sealing materials is 50% by weight or more. <1> ~ <4> 1. The silicone rubber composition for sealing materials according to claim 1, <6> Shore A hardness is 85 or less. <1> ~ <5> 1. The silicone rubber composition for sealing materials according to claim 1, <7> <1> ~ <6> A sealing material comprising the silicone rubber composition for sealing material according to any one of the above items. <8> two or more cells, a thermal insulator, and a container; <7> A battery comprising the sealing material according to claim 1, the two or more cells, the insulating material, and the sealing material are housed in the container; the thermal insulation material is arranged to divide the inside of the container into two or more compartments, The two or more cells are arranged in two or more of the two or more compartments, The sealing material is arranged to close a gap between the heat insulating material and the container. battery. <9> A battery comprising two or more cells, a thermal insulator, a container, and a seal, The sealing material is <1> ~ <6> A battery comprising the silicone rubber composition for sealing material according to any one of the above items.

[0048] The present invention also includes the following configurations. [A1] A method for producing a silicone rubber composition for sealing materials, comprising the steps of: The method includes mixing a flame-retardant silicone rubber compound and a fiber-based flame retardant; When the blending amount of the flame-retardant silicone rubber compound is 100 parts by weight, the blending amount of the fiber-based flame retardant is 5 to 60 parts by weight, The flame-retardant silicone rubber compound is rated V-0 or higher according to the UL94 standard. [A2] 1. A method for improving the flame retardancy of a flame retardant silicone rubber compound, comprising: The method includes mixing a flame-retardant silicone rubber compound and a fiber-based flame retardant; When the blending amount of the flame-retardant silicone rubber compound is 100 parts by weight, the blending amount of the fiber-based flame retardant is 5 to 60 parts by weight, The flame-retardant silicone rubber compound is rated V-0 or higher according to the UL94 standard. [Example]

[0049] Hereinafter, one embodiment of the present invention will be described in detail with reference to examples, although the present invention is not limited to these examples.

[0050] [Materials used] Flame-retardant silicone rubber compound Flame-retardant silicone rubber compound A (KE-5612E-U, Shin-Etsu Chemical Co., Ltd., vinyl methyl silicone rubber compound, UL94 standard: V-0) Flame-retardant silicone rubber compound B (SH502U, Dow Toray Industries, Inc., vinyl methyl silicone rubber compound, UL94 standard: V-0) Flame retardants Fiber-based flame retardant A (Rockwool, RS490ELS-Roxul1000, Rapinus, fiber length: 150-250 μm, shot content: 0.2% (average)) Fiber-based flame retardant B (Rockwool, FS021, JFE Rockfiber Corporation, shot content: 30-40%) Fiber-based flame retardant C (aramid fiber, Twaron (registered trademark) 3091, Teijin Limited, fiber length: 650-1150 μm) Phosphorus-based flame retardant (Fireguard FCX-210, Teijin Limited) Inorganic flame retardants (particulate aluminum hydroxide) Hardener Curing agent A (C-3, Shin-Etsu Chemical Co., Ltd., dicumyl peroxide) Curing agent B (RC4 50P, Dow Toray Industries, Inc., 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane)

[0051] [Examples 1 to 8, Comparative Examples 1 to 5] A vulcanized rubber sheet was prepared according to the following procedure. The vulcanized rubber sheet was used to prepare test pieces for the tests described below. 1. The components listed in Table 1 were kneaded using an open roll. The temperature during kneading was 20 to 100° C. The kneading time was 10 to 30 minutes. 2. Unvulcanized rubber sheets were produced from the resulting kneaded material. 3. The unvulcanized rubber sheet was press-vulcanized at 165°C for 10 minutes. 4. Further, secondary vulcanization was carried out for 4 hours at 200°C. In this way, a vulcanized rubber sheet with a thickness of 2 mm was obtained.

[0052] [Test method] [1. Hardness in normal state] The Shore A hardness of the silicone rubber composition was measured before the heat resistance test or the flame test in accordance with JIS K6253. The specific procedure is as follows. 1. Three 2mm thick vulcanized rubber sheets were stacked together to form the test specimen. 2. Measurements were made using a Type A durometer at 23°C and a relative humidity of 50%. The peak value of the durometer was taken as the Shore A hardness.

[0053] [2. Heat resistance test] The silicone rubber compositions were subjected to a heat resistance test in accordance with JIS K6262, and then the compression set was measured. The specific procedure was as follows. 1. Three sheets with a diameter of 13 mm were cut out from a 2 mm thick vulcanized rubber sheet. These three sheets were stacked together to form the test piece. 2. The test piece was compressed by 25% and kept in air at 150°C for 70 hours. 3. The compression was released and the compression set of the silicone rubber composition was calculated. A silicone rubber composition with a small compression set value is said to have a high recovery force even after being compressed for a long period of time.

[0054] [3. Dispersibility] The dispersibility of the fiber-based flame retardant was evaluated based on the appearance of the silicone rubber composition, using the following specific procedure. 1. The unvulcanized rubber sheet after kneading produced in the Examples or Comparative Examples was cut out with a cutter. 2. Using a filler dispersion meter (Dispersion Checker DCF50A, M&K Corporation), the dispersion of the fiber-based flame retardant in the cross section of the cut unvulcanized rubber sheet was measured. The measurement results were evaluated according to the following criteria. A higher dispersion is preferable. 1: Dispersion degree less than 80% 2: Dispersion degree 80% or more, less than 90% 3:Dispersion degree of 90% or more

[0055] [4. Combustion test] The silicone rubber compositions were subjected to a combustion test to evaluate their flame retardancy and shape retention after combustion. The specific procedures are as follows. 1. A test piece measuring 10 mm wide and 100 mm long was cut out from a 2 mm thick vulcanized rubber sheet. 2. The test specimen was fixed to the jig, and the burner flame was adjusted so that the temperature at the combustion point was 800°C. 3. The test piece was exposed to flame for 2 minutes. The time when the flame started to be applied was set as 0 seconds, and the time (seconds) when smoke and flames appeared were recorded. The duration (seconds) from the time the flame appeared until it was extinguished was also recorded. 4. After burning, the deflection and appearance of the test specimen were visually inspected.

[0056] The criteria for judging the deflection and appearance of the test piece after the combustion test are as follows: Deflection 1: There is a large deflection. 2: Moderate deflection. 3: There is a small deflection. 4: No deflection (or only very small deflection). Appearance 1: Poor. Numerous cracks, peeling, breaks, or shatters. 2: Normal. Large cracks. 3: Good, small or medium cracks present. 4: Very good. Only whitening and no cracks (or only very small cracks). [Table 1] TIFF2025120421000002.tif179169 TIFF2025120421000003.tif215169

[0057] 〔result〕 The test results are shown in Table 1. Comparing Examples 1 to 5 with Comparative Example 1, it is clear that the silicone rubber composition containing the added fiber-based flame retardant has improved flame retardancy. That is, the time at which smoke and flame appeared was later in Examples 1 to 5 than in Comparative Example 1. Furthermore, the flame duration was shorter in Examples 1 to 5 than in Comparative Example 1.

[0058] Improvements in flame retardancy were observed even when the type of flame-retardant silicone rubber compound was changed (Example 6). Similarly, improvements in flame retardancy were observed when the type of fiber-based flame retardant was changed (Examples 7 to 9). In Comparative Examples 2 and 3, in which a phosphorus-based flame retardant was added, a tendency for flame retardancy to decrease was observed. In Comparative Examples 4 and 5, in which an inorganic flame retardant was added, the flame retardancy was equivalent to that of the Examples, but the deflection and appearance after the combustion test were extremely poor.

[0059] Comparing the Examples, the degree of improvement in flame retardancy was greater in Examples 2 to 5 than in Example 1. Therefore, from the viewpoint of flame retardancy, it is preferable to increase the content of the fibrous flame retardant compared to Example 1 (for example, 15 parts by weight or more per 100 parts by weight of the flame-retardant silicone rubber compound).

[0060] Furthermore, the Shore A hardness in the normal state was smaller in Examples 1 to 4 than in Example 5. Therefore, from the viewpoint of use in general sealing material applications, it is preferable to make the content of the fibrous flame retardant lower than in Example 5 (for example, 45 parts by weight or less per 100 parts by weight of the flame-retardant silicone rubber compound).

[0061] Regarding the dispersibility of the fibrous flame retardant in the silicone rubber composition, fibrous flame retardant A was the best (Examples 1 to 6), followed by fibrous flame retardant B (Examples 7 and 8), and then fibrous flame retardant C (Example 9). Therefore, from the viewpoint of dispersibility, rock wool is preferred as the fibrous flame retardant. Similarly, from the viewpoint of dispersibility, a low shot content of the fibrous flame retardant is preferred (for example, 0.5 wt % or less based on the weight of the fibrous flame retardant). [Industrial Applicability]

[0062] The present invention can be used, for example, as a sealing material for batteries and the like. [Explanation of symbols]

[0063] 1: Sealing material 2: Cell 3: Insulation material 4: Container 10:Battery

Claims

1. The flame-retardant silicone rubber compound and the fiber-based flame retardant are included, When the content of the flame-retardant silicone rubber compound is 100 parts by weight, the content of the fiber-based flame retardant is 5 to 60 parts by weight, The flame-retardant silicone rubber compound is a silicone rubber composition for battery sealants that meets the UL94 standard of V-0 or higher.

2. 2. The silicone rubber composition for battery sealing materials according to claim 1, wherein the fiber-based flame retardant comprises one or more selected from the group consisting of artificial mineral fibers, natural mineral fibers, and synthetic organic fibers.

3. The fiber-based flame retardant contains the artificial mineral fiber, The man-made mineral fiber includes rock wool. The silicone rubber composition for battery sealing materials according to claim 2 .

4. 2. The silicone rubber composition for battery sealing materials according to claim 1, wherein the fiber-based flame retardant has a fiber length of 50 to 500 μm and a shot content of 5% by weight or less.

5. 2. The silicone rubber composition for a battery seal according to claim 1, wherein the content of said flame-retardant silicone rubber compound in said silicone rubber composition for a battery seal is 50% by weight or more.

6. 2. The silicone rubber composition for battery sealing materials according to claim 1, which has a Shore A hardness of 85 or less.

7. A battery sealant comprising the silicone rubber composition for battery sealants according to any one of claims 1 to 6.

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