Rubber composition and rubber member using the same

Abstract

To provide a non-halogen flame-retardant rubber composition having low smoke emission when burning, no generation of toxic halogenated gases and properties such as weather resistance, heat resistance, and ozone resistance suitable for applications such as hoses, gaskets, and packings.SOLUTION: There is provided a rubber composition which comprises an ethylene-α-olefin-non-conjugated polyene copolymer rubber, intumescent phosphate as a flame retardant and a phosphoric acid ester-based plasticizer having a solubility parameter (SP value) of less than 8.5 (cal / cm3)1 / 2 as a plasticizer, wherein the blending amount of the intumescent phosphate is 25 vol.% or more based on the total volume of the rubber composition and the blending amount of the phosphoric acid ester-based plasticizer is more than 1 pt.wt. and 30 pts.wt. or less based on 100 pts.wt. of the ethylene-α-olefin-non-conjugated polyene copolymer rubber.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a rubber composition and a rubber member used in an environment where flame retardancy is required. More specifically, the present invention relates to a flame-retardant rubber composition and a rubber member suitable for use as a hose, gasket, packing, etc. in an environment where flame retardancy is required.

Background Art

[0002] When attempting to impart flame retardancy to a rubber material, a technique of blending a flame retardant into a rubber composition used as a raw material is known. As the flame retardant, phosphorus-based flame retardants, halogen-based flame retardants, antimony-based flame retardants, hydrated metal compound-based flame retardants, etc. are known. In particular, it is generally known that an excellent flame retardant effect can be obtained by using a halogen-based flame retardant and antimony trioxide in combination. However, in recent years, due to the increasing environmental awareness, it has been required to improve the flame retardancy while reducing the smoke generation during combustion (low smoke generation) and further reducing the generation of toxic gases during combustion. From such a viewpoint, the technique of using a halogen-based flame retardant and antimony trioxide in combination has problems in terms of the environment.

[0003] Patent Document 1 provides a rubber composition for a buffer rubber for railway vehicles, which contains polychloroprene rubber and natural rubber as rubber components, uses an intumescent phosphate as a flame retardant, does not contain a halogen-based flame retardant and antimony trioxide, has low smoke generation during combustion, and takes environmental considerations into account with less generation of toxic gases during combustion.

[0004] Although a non-halogenated intumescent flame retardant is used as the flame retardant in the composition, when using polychloroprene rubber or natural rubber as hoses, gaskets, packings, etc., it is insufficient in terms of physical properties such as weather resistance, heat resistance, and ozone resistance. In addition, since the polychloroprene rubber component contains chlorine, it cannot be said to be a completely non-halogenated rubber composition, and it releases halogen upon combustion, so it cannot be said to be an environmentally considerate rubber composition. On the other hand, when a hydrated metal compound-based flame retardant is used in an ethylene-α-olefin-non-conjugated polyene copolymer rubber, it is difficult to obtain sufficient flame retardancy.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, the problem to be solved by the present invention is to provide a non-halogenated flame-retardant rubber composition that uses a rubber material other than polychloroprene rubber and natural rubber, has low smoke generation during combustion, does not generate toxic halogen-based gases, and has physical properties such as weather resistance, heat resistance, and ozone resistance suitable for applications such as hoses, gaskets, and packings.

Means for Solving the Problems

[0007] The inventor of the present invention has adopted a rubber material that does not contain halogen such as chlorine as the rubber component, used a specific phosphate as the flame retardant in a specific blending amount, and used a specific phosphate ester-based plasticizer as the plasticizer in a specific blending amount to solve the above problems. That is, the present invention includes the following. [1] An ethylene-α-olefin-non-conjugated polyene copolymer rubber, an intumescent phosphate as a flame retardant, and a phosphate ester-based plasticizer with a solubility parameter (SP value) of 8.5 (cal / cm 3) 1 / 2 A rubber composition containing a phosphate ester plasticizer having a solubility parameter (SP value) of less than 8.5 (cal / cm The blending amount of the intumescent phosphate is 25% by volume or more based on the total volume of the rubber composition, The blending amount of the phosphate ester plasticizer is greater than 1 part by weight and 30 parts by weight or less with respect to 100 parts by weight of the ethylene-α-olefin-non-conjugated polyene copolymer rubber, Rubber composition. [2] The rubber composition according to [1], wherein the ethylene-α-olefin-non-conjugated polyene copolymer rubber is at least one selected from the group consisting of ethylene-propylene-diene copolymer (EPDM) and ethylene-butene-diene copolymer (EBDM). [3] The rubber composition according to [1] or [2], wherein the intumescent phosphate contains magnesium phosphate and ammonium phosphate. [4] A rubber member obtained by crosslinking and molding the rubber composition according to any one of [1] to [3]. [Advantages of the Invention]

[0008] According to the present invention, in an environment where flame retardancy is required, a flame-retardant rubber composition suitable for hoses, gaskets, packings, etc., which has low smoke generation during combustion and takes into account the environmental aspect of not generating toxic halogen-based gases, can be provided. [Embodiments for Carrying Out the Invention]

[0009] The rubber composition according to the present invention is an ethylene-α-olefin-non-conjugated polyene copolymer rubber, an intumescent phosphate as a flame retardant, and a phosphate ester plasticizer having a solubility parameter (SP value) of less than 8.5 (cal / cm 3 ) 1 / 2 A rubber composition containing a phosphate ester plasticizer having a solubility parameter (SP value) of less than 8.5 (cal / cm The blending amount of the intumescent phosphate is 25% by volume or more based on the total volume of the rubber composition, The compounding amount of the phosphate ester plasticizer is greater than 1 part by weight and 30 parts by weight or less with respect to 100 parts by weight of the ethylene-α-olefin-non-conjugated polyene copolymer rubber. It is a rubber composition. It will be described in order below.

[0010] [Ethylene-α-olefin-non-conjugated polyene copolymer rubber] As the α-olefin in the ethylene-α-olefin-non-conjugated polyene copolymer rubber, an α-olefin having 3 to 20 carbon atoms is preferable, and examples thereof include linear α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and branched α-olefins such as 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene. Preferably, it is propylene or 1-butene.

[0011] Examples of non-conjugated polyenes include chain non-conjugated dienes such as 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene, etc.; cyclic non-conjugated dienes such as cyclohexadiene, dicyclopentadiene, methyltetralin, 5-vinyl-2-norbornene, 5-(2-propenyl)-2-norbornene, 5-(3-butenyl)-2-norbornene, 5-(4-pentenyl)-2-norbornene, 5-(5-hexenyl)-2-norbornene, 5-(5-heptenyl)-2-norbornene, 5-(7-octenyl)-2-norbornene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, etc.; and trienes such as 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, 1,3,7-octatriene, 1,4,9-decatriene, 6,10-dimethyl-1,5,9-undecatriene, 5,9-dimethyl-1,4,8-decatriene, 4-ethylidene-8-methyl-1,7-nonadiene, 13-ethyl-9-methyl-1,9,12-pentadecatriene, 8,14,16-trimethyl-1,7,14-hexadecatriene, 4-ethylidene-12-methyl-1,11-pentadecadiene, etc. Preferably, they are chain or cyclic non-conjugated dienes.

[0012] Therefore, the ethylene-α-olefin-non-conjugated polyene copolymer rubber is preferably at least one selected from the group consisting of ethylene-propylene-non-conjugated diene copolymer (EPDM) and ethylene-butene-non-conjugated diene copolymer (EBDM).

[0013] [Intumescent phosphate] In the present invention, an intumescent phosphate is used as a flame retardant. Intumescent phosphates form an intumescent (foaming and swelling layer) on the rubber surface during the combustion of ethylene-α-olefin-non-conjugated polyene copolymer rubber, and by virtue of their heat insulation effect and high gas barrier effect, they suppress the acceleration of rubber decomposition due to heat and the supply of fuel to the combustion site by the generation of decomposition gases, thereby stopping the combustion cycle and improving the flame retardancy of the rubber.

[0014] Examples of phosphoric acid constituting the salt include inorganic phosphoric acids such as orthophosphoric acid, phosphorous acid, hypophosphorous acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, and tetraphosphoric acid; and organic phosphoric acids such as phosphonic acid and phosphinicocarboxylic acid. Among these, orthophosphoric acid is preferred. As the phosphate, it is particularly preferable to use magnesium phosphate or ammonium phosphate. Note that phosphoric acid can also be a condensed one (polyphosphoric acid). Examples of polyphosphoric acid include chain polyphosphoric acid and cyclic polymetaphosphoric acid. The degree of condensation of these polyphosphoric acids is usually 3 to 50.

[0015] Examples of the flame retardant containing magnesium phosphate, ammonium phosphate, etc. include "FP-2500S" manufactured by ADEKA Corporation.

[0016] In the present invention, in order to obtain flame retardancy (equivalent to V-0 according to the UL94V standard), it is preferable that the rubber composition contains 25% by volume or more of the intumescent phosphate.

[0017] [Plasticizer] From the viewpoint of not inhibiting flame retardancy, it is preferable to use a phosphate ester-based plasticizer as the plasticizer. Due to the compatibility with ethylene-α-olefin-non-conjugated polyene copolymer rubber, the SP value (solubility parameter) of the phosphate ester-based plasticizer is 8.4 (cal / cm 3 ) 1 / 2 The following is preferable. The SP value (solubility parameter) is 8.4 (cal / cm 3 ) 1 / 2When it is greater than or more than 30 parts by weight, the compatibility with the ethylene-α-olefin-non-conjugated polyene copolymer rubber is poor, and a phenomenon called bleed occurs where the plasticizer oozes out from the rubber composition, resulting in a decrease in kneading processability, an increase in the defective rate due to mold contamination during vulcanization, and problems with adhesion to metals. Further, as a product, it is treated as a defective appearance.

[0018] Here, the SP value is the solubility parameter, and a very large amount of data has been proposed, such as measured values from evaporation latent heat and solubility, or calculation methods by Small, Fedors, or Hansen. In the present invention, however, the value obtained by the widely known Hoy method is used. Examples of literature on the Hoy method include H.L. Hoy: J. Paint Tech., 42(540), 76-118(1970) and SP Value Basics, Applications, and Calculation Methods (Yamamoto, Information Center, 2005).

[0019]

Number

[0020] Specific examples of the phosphate ester plasticizer include tributyl phosphate (TBP), tris(2-ethylhexyl) phosphate (TOP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), and the like.

[0021] When the ethylene-α-olefin-non-conjugated polyene copolymer rubber is 100 parts by weight, the phosphate ester plasticizer is preferably 30 parts by weight or less.

[0022] [Other Additives]

[0023] In the rubber composition according to the present invention, in addition to the rubber component, phosphate, and plasticizer, fillers such as carbon black and clay, vulcanizing agents, vulcanization accelerators, vulcanization accelerator aids, vulcanization retarders, softening agents, anti-aging agents, processing aids, and other compounding agents usually used in the rubber industry can be appropriately compounded and used within a range that does not impair the effects of the present invention.

[0024] [Carbon black] By blending carbon black as a filler in the rubber composition according to the present invention, it is possible to improve the mechanical properties such as the breaking strength of the obtained rubber member. There are various types of carbon black, and an appropriate one is selected and used according to the application. As the carbon black, known ones can be used, and generally, SAF, ISAF, HAF, MAF, FEF, GPF, SRF, etc., which are furnace blacks commonly used in rubber, can be mentioned. The carbon black may be used alone or blended with two or more kinds.

[0025] The carbon black is preferably blended in an amount of 10 parts by weight or more, more preferably 20 parts by weight or more, preferably 120 parts by weight or less, and more preferably 80 parts by weight or less with respect to 100 parts by weight of the ethylene-α-olefin-non-conjugated polyene copolymer rubber in the rubber composition according to the present invention.

[0026] There are various commercially available carbon blacks that can be used in the present invention. Specifically, Asahi #60, #60U, #50, #50U, #51, #35 (above, Asahi Carbon Co., Ltd.), SHOW BLACK N762 (Showa Cabot Co., Ltd.), SEAST S (Tokai Carbon Co., Ltd.), DIABLACK R, DIABLACK N760M (above, Mitsubishi Chemical Corporation), etc., and SRF grade carbon blacks can be mentioned.

[0027] [Vulcanizing agent] As the vulcanizing agent, organic peroxides and the like can be used. As the organic peroxide, any one can be used as long as it decomposes at a temperature of 100 ° C or higher to generate radicals. The organic peroxide is generally selected in consideration of the film-forming temperature, the adjustment conditions of the composition, the curing (bonding) temperature, the heat resistance of the adherend, and the storage stability. In particular, those having a decomposition temperature of 70 ° C or higher for a half-life of 10 hours are preferred. If the decomposition temperature is less than 70 ° C, the processability during rubber kneading or rubber molding may deteriorate.

[0028] Examples of organic peroxides include peroxycarbonates, diacyl peroxides, dialkyl peroxides, peroxyketals, alkyl peresters, and the like.

[0029] Specific examples of organic peroxides are 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, t-butyl cumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumyl peroxide, α,α'-bis(t-butylperoxyisopropyl)benzene, n-butyl-4,4-bis(t-butylperoxy)valerate, 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)trimethylcyclohexane, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, t-butyl peroxybenzoate, benzoyl peroxide, t-butyl peroxyacetate, methyl ethyl ketone peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, methyl ethyl ketone peroxide, 2,5-dimethylhexyl-2,5-bisperoxybenzoate, t-butyl hydroperoxide, p-menthane hydroperoxide, p-chlorobenzoyl peroxide, hydroxyheptyl peroxide, Chlorohexanone peroxide, Octanoyl peroxide, Decanoyl peroxide, Lauroyl peroxide, Cumyl peroxyoctoate, Succinic peroxide, Acetyl peroxide, t-Butyl peroxy (2-ethylhexanoate), m-Toluoyl peroxide, t-Butyl peroxyisobutyrate, and 2,4-Dichlorobenzoyl peroxide can be mentioned, but it is not limited thereto.

[0030] One kind of organic peroxide may be used, or two or more kinds may be used in combination. Further, these can also be used as diluted products or masterbatch products having silica or calcium carbonate as a carrier. All of these are available as commercial products (for example, Parkmill D, Parkmill D-40, Parkmill D-40MB manufactured by NOF Corporation).

[0031] The compounding amount of the organic peroxide is not particularly limited. Preferably, the compounding amount of the organic peroxide is 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the ethylene-α-olefin-non-conjugated polyene copolymer rubber in the rubber composition according to the present invention.

[0032] [Vulcanization accelerator] As the vulcanization accelerator, triallyl isocyanurate, triallyl cyanurate, triallyl isocyanate, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, glycidyl methacrylate, diallyl phthalate, quinone dioximes, bismaleimides, metal dimethacrylates, metal diacrylates, sulfur compounds, 1,2-polybutadiene, etc. can be used. All of these are available as commercial products (for example, Sun Ester TMP manufactured by Sanshin Chemical Industry Co., Ltd.).

[0033] The compounding amount of the vulcanization accelerator is not particularly limited. Preferably, the compounding amount of the vulcanization accelerator is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the ethylene-α-olefin-non-conjugated polyene copolymer rubber in the rubber composition according to the present invention.

[0034] [Vulcanization accelerator aid] Examples of the vulcanization accelerator aid include fatty acids such as stearic acid, oleic acid, and cottonseed fatty acid, and metal oxides such as magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, red lead, white lead, litharge, hydrotalcite, and zinc white.

[0035] The addition amount of the vulcanization accelerator aid is set according to the crosslinking agent used. Usually, it is 0.1 to 10 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the ethylene-α-olefin-non-conjugated polyene copolymer rubber in the rubber composition according to the present invention.

[0036] [Vulcanization retarder] Examples of the vulcanization retarder include phthalic anhydride, benzoic acid, salicylic acid, N-nitrosodiphenylamine, N-(cyclohexylthio)-phthalimide (CTP), sulfonamide derivatives, diphenylurea, bis(tridecyl)pentaerythritol-diphosphite, etc., and N-(cyclohexylthio)-phthalimide (CTP) can be mentioned.

[0037] The compounding amount of the vulcanization retarder is not particularly limited. Preferably, the compounding amount of the vulcanization retarder is usually 0.1 to 10 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the ethylene-α-olefin-non-conjugated polyene copolymer rubber in the rubber composition according to the present invention.

[0038] [Softening agent] Examples of softeners include petroleum-based softeners such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, and petrolatum; coal-tar-based softeners such as coal tar and coal-tar pitch; vegetable oil-based softeners such as castor oil, linseed oil, rapeseed oil, and coconut oil; waxes such as tall oil, suet, beeswax, carnauba wax, and lanolin; aliphatic dibasic acid esters such as bis(2-ethylhexyl) sebacate; orthophosphoric acid esters such as tris(2-ethylhexyl) phosphate; fatty acids and fatty acid salts such as ricinoleic acid, palmitic acid, stearic acid, barium stearate, calcium stearate, and zinc laurate; and synthetic polymer substances such as petroleum resins, atactic polypropylene, and coumarone-indene resins. All of these are commercially available.

[0039] The compounding amount of the softener is not particularly limited. Preferably, the compounding amount of the softener is usually 0.1 to 10 parts by weight, preferably 0.5 to 3 parts by weight, per 100 parts by weight of the ethylene-α-olefin-non-conjugated polyene copolymer rubber in the rubber composition according to the present invention.

[0040] [Antioxidant] As the antioxidant, known ones can be used, and examples include amine-ketone-based antioxidants, phenolic antioxidants, imidazole-based antioxidants, and amine-based antioxidants. Specific commercially available products include Nocrack CD (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., 4,4'-bis(α,α-dimethylbenzyl)diphenylamine), Nocrack 224 (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., 2,2,4-trimethyl-1,2-dihydroquinoline polymer), and the like.

[0041] The compounding amount of the antioxidant is not particularly limited. Preferably, the compounding amount of the antioxidant is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of the ethylene-α-olefin-non-conjugated polyene copolymer rubber in the rubber composition according to the present invention.

[0042] [Processing Aids] For processing aids, those suitable for the purpose may be selected. Generally, well-known higher fatty acids, fatty acid metal salts, fatty acid esters, fatty acid amides, hydrocarbons, etc. may be used alone or in combination of two or more. All of these are available as commercial products.

[0043] The compounding amount of the processing aid is not particularly limited. Preferably, the compounding amount of the antioxidant is 0.1 to 10 parts by weight based on 100 parts by weight of the ethylene-α-olefin-non-conjugated polyene copolymer rubber in the rubber composition according to the present invention. Also, silica, calcium carbonate, fine powder talc, fine powder aluminum silicate, etc. may be used as reinforcing agents.

[0044] [Method for preparing rubber composition] The rubber composition according to the present invention can be prepared by compounding the above components using a known method for preparing a rubber composition. For example, using a known mixer such as a Banbury mixer, a single-screw or twin-screw extruder, a kneader, an internal mixer such as an intermix, the softening agent, the reinforcing agent, the antioxidant, etc. and the ethylene-α-olefin-non-conjugated polyene copolymer rubber are kneaded at a temperature of 80 to 170°C for 3 to 10 minutes, and then, using rolls such as an open roll or a kneader, a crosslinking agent, a crosslinking accelerator, a processing aid, etc. are added as necessary at a temperature of 40 to 80°C and kneaded for 5 to 30 minutes to prepare it.

[0045] The rubber composition according to the present invention is particularly suitable for the production of rubber members used in gaskets such as joint sheet gaskets, rubber sheet gaskets, herringbone gaskets (sanitary gaskets), spiral gaskets (semi-metallic gaskets), metal jacket gaskets, metal joints, etc., packings such as gland packings, mechanical seals, oil seals, etc., and O-rings.

[0046] [Rubber member] The rubber composition obtained by kneading can be crosslinked and formed into a desired rubber member by a known extrusion molding machine, compression molding machine, injection molding machine, transfer molding machine, etc. The molding conditions are, for example, 150 to 220 °C and 1 to 30 minutes.

Examples

[0047] Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples and Comparative Examples.

[0048] <Method for Preparing Rubber Composition> 〇Manufacturing Method of Rubber Composition For 100 parts by weight of rubber, rubber compositions of Examples 1 to 6 and Comparative Examples 1 to 6 were compounded according to the compounding formulations in Table 1 and kneaded on a 6-inch open roll to prepare rubber compositions.

[0049] The details of each formulation described in Table 1 are shown below. a) Rubber Component Ethylene-propylene-diene copolymer (EPDM); manufactured by Sumitomo Chemical Co., Ltd., trade name "Esprene 501A" b) Flame Retardant Intumescent phosphate (containing magnesium phosphate and ammonium phosphate); manufactured by ADEKA Corporation, trade name "Adekastab FP-2500S" c) Carbon Black; manufactured by Asahi Carbon Co., Ltd., "Asahi 60U" d) Plasticizer Phosphate ester plasticizer; manufactured by Daihachi Chemical Industry Co., Ltd., Trade name "TOP" SP value 8.2 Trade name "TBP" SP value 8.6 Trade name "TCP" SP value 9.9 Sebacic acid ester plasticizer; manufactured by Daihachi Chemical Industry Co., Ltd., Trade name "DOS" SP value 8.4 e) Antioxidant; manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., trade name "Nocrack 224" f) Processing Aid Stearic acid; manufactured by Shin Nippon Rika Co., Ltd., trade name "Stearic Acid 50S" g) Vulcanizing agent Organic peroxide; manufactured by NOF Corporation, trade name "Perk Mill D40" h) Vulcanization accelerator; manufactured by Sanshin Chemical Industry Co., Ltd., trade name "Sun Ester TMP"

[0050]

Table 1

[0051] <Test piece preparation method and test conditions> 〇Test piece preparation conditions The rubber composition obtained by kneading was cross-linked using a press molding machine to obtain a 2-mm-thick sheet-shaped test piece.

[0052] 〇Test conditions: (Normal physical properties) The hardness of the rubber member was measured using a durometer hardness type A in accordance with JIS K6253. The tensile strength, elongation, and 100% modulus value of the rubber member were measured in accordance with JIS K6251. For the test piece, dumbbell No. 5 shape was used based on JIS K 6251.

[0053] (Flame retardancy test) The flame retardancy of the rubber member was measured in accordance with the UL94V standard. A test piece of a predetermined size (13 mm × 125 mm × 2 mm) was cut out from the above sheet-shaped test piece, and a vertical burning test in accordance with the UL94V standard was performed on the test piece. Specifically, the test piece was vertically attached to a predetermined clamp, and indirect flaming with a 20-mm flame was performed twice for 10 seconds, and the combustion behavior was used for judgment. "Equivalent to V-0" of the UL94V standard was marked as ○, and the others were marked as ×.

[0054] (Appearance of rubber vulcanizate) The appearance of the rubber vulcanizate was visually observed, and those without bleeding of the plasticizer were marked as ○, and those with bleeding were marked as ×.

[0055] (Compression set test) The heat resistance is evaluated using the compression set test of JIS K 6262:2018. A test is conducted for 70 hours in an environment of 25% compression and 150°C. When the compression set at that time is 40% or less, it is regarded as having heat resistance and marked as ○. "Unable to measure" means that the test piece could not be produced due to bleeding of the unvulcanized rubber.

Industrial Applicability

[0056] According to the present invention, in an environment where flame retardancy is required, a flame-retardant rubber composition suitable for hoses, gaskets, packings, etc., which have low smoke generation during combustion and consider the environmental aspect of not generating toxic halogen-based gases, can be provided.

Claims

1. An ethylene-α-olefin-non-conjugated polyene copolymer rubber, an intumescent phosphate as a flame retardant, and a phosphate plasticizer having a solubility parameter (SP value) of less than 8.5 (cal / cm ３ ) １／２ A rubber composition containing a rubber composition, The blending amount of the intumescent phosphate is 25% by volume or more based on the total volume of the rubber composition, and the blending amount of the phosphate ester plasticizer is greater than 1 part by weight and 30 parts by weight or less with respect to 100 parts by weight of the ethylene-α-olefin-non-conjugated polyene copolymer rubber, a rubber composition.

2. The rubber composition according to claim 1, wherein the ethylene-α-olefin-non-conjugated polyene copolymer rubber is at least one selected from the group consisting of ethylene-propylene-diene copolymer (EPDM) and ethylene-butene-diene copolymer (EBDM).

3. The rubber composition according to claim 1 or 2, wherein the intumescent phosphate contains magnesium phosphate and ammonium phosphate.

4. A rubber member obtained by crosslinking and molding the rubber composition according to any one of claims 1 to 3.

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