Title of Invention	CHLORINATED RUBBER COMPOSITION AND HOSE
Abstract	A chlorinated rubber composition including a chlorinated rubber, a metal deactivator, an acid acceptor, and an antioxidant respectively at a particular amount is provided. The chlorinated rubber composition is capable of providing a chlorinated rubber composition which can be used in producing a hose exhibiting excellent resistance to degradation by zinc together with the sufficient physical properties such as resistance to thermal aging, oil resistance, and adhesion, as well as a hose produced by using such chlorinated rubber composition for the rubber layer.

Title of Invention

CHLORINATED RUBBER COMPOSITION AND HOSE

Abstract

A chlorinated rubber composition including a chlorinated rubber, a metal deactivator, an acid acceptor, and an antioxidant respectively at a particular amount is provided. The chlorinated rubber composition is capable of providing a chlorinated rubber composition which can be used in producing a hose exhibiting excellent resistance to degradation by zinc together with the sufficient physical properties such as resistance to thermal aging, oil resistance, and adhesion, as well as a hose produced by using such chlorinated rubber composition for the rubber layer.

Full Text	DESCRIPTION CHLORINATED RUBBER COMPOSITION AND HOSE Technical Field [0001] This invention relates to a chlorinated rubber composition and a hose produced by using such chlorinated rubber composition. Background Art [0002] Chlorinated rubbers (for example, chlorinated polyethylene rubbers and chlorosulfonated polyethylenes) have excellent properties such as resistance to thermal aging, oil resistance, cold resistance, weatherability, flame resistance, and electric properties, and they are used as the molding materials of various high pressure hoses as such as automobile power stearing hoses; cable sheaths; gaskets; packings; and other molded articles. [0003] Of such molding materials, the high pressure hoses produced by using a chlorinated rubber for the rubber layer should have sufficient resistance to degradation by zinc because, when such hoses become in contact with a metal part, and in particular, with zinc-plated joint at a high pressure and a high temperature, the chlorinated rubber constituting the rubber layer is rapidly and harshly degraded or hardened with cracks formation in the rubber layer or embrittlement or tearing of the rubber layer. [0004] As a technnique to solve such problems, patent document 1 discloses a composition for chlorinated polyethylene crosslinked rubber comprising (a) 100 parts by weight of chlorinated polyethylene, (b) 2 to 10 parts by weight of organic peroxide, (c) 3 to 20 parts by weight of crosslinking aid, and (d) 3 to 40 parts by weight of at least one acid acceptor selected from hydrotalcites and zeolites (claim 1}. [0005] Patent document 1: JP 2001-226546 A Disclosure of the Invention Problems to be solved by the Invention [0006] However, the hose produced by using the composition for a chlorinated polyethylene crosslinked rubber of JP 2001- 226546 A for the rubber layer was found to be insufficient in the resistance to degradation by zinc despite its sufficient physical properties such as resistance to thermal aging, oil resistance, and adhesion. In view of the situation as described above, an object of the present invention is to provide a chlorinated rubber composition which can be used in producing a hose exhibiting excellent resistance to degradation by zinc together with the sufficient physical properties such as resistance to thermal aging, oil resistance, and adhesion. Another object of the present invention is to provide a hose produced by using such chlorinated rubber composition for the rubber layer. Means to solve the Problems [0007] In order to solve the problems as described above, the inventors of the present invention made an intensive study and found that a hose exhibiting excellent resistance to degradation by zinc together with the sufficient physical properties such as resistance to thermal aging, oil resistance, and adhesion can be produced by using a chlorinated rubber composition containing a metal deactivator, an acid acceptor, and an antioxidant respectively at a particular amount in relation to the chlorinated rubber composition. The present invention has been completed on the bases of such finding. Accordingly, the present invention provides the following (1) to (5): [0008] (1) A chlorinated rubber composition comprising a chlorinated rubber, a metal deactivator, an acid acceptor, and an antioxidant, wherein the metal deactivator is included at a content of at least 0.3 parts by weight in relation to 100 parts by weight of the chlorinated rubber, the acid acceptor is included at a content of at least 1 parts by weight in relation to.100 parts by weight of the chlorinated rubber, and the antioxidant is included at a content of 0.1 to 10 parts by weight in relation to 100 parts by weight of the chlorinated rubber. [0009] (2) A chlorinated rubber composition according to (1) wherein the metal deactivator is at least one member selected from the group consisting of 1,2,3-benzotriazole, 3-(N- salicyloyl)amino-1,2,4-triazole, decamethylenedicarboxylic acid disalicyloylhydrazide, N,N'-bis[3-(3,5-di-t-butyl-4- hydroxyphenyl)propionyl]hydrazine, 2,2'-oxamidebis[ethyl 3- (3,5-t-butyl-4-hydroxyphenyl)propionate], oxalic acid bisbenzylidenehydrazide, isophthalic acid bis(2-phenoxy propionylhydrazide), 2,4,6-triamino-l,3,5-triazine, ethylenediandnetetraacetic acid, alkali metal (such as Li, Na, or K) salt of ethylenediandnetetraacetic acid, tris[2-t-butyl- 4-thio(2'-methyl-4' -hydroxy-5' -t-butyl) phenyl-5-methyl]- phenyl phosphite, and 3,9-bis[2-(3,5-diamino-2,4,6- triazaphenyl) ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane. [0010] (3) A chlorinated rubber composition according to (1) or (2) wherein the acid acceptor is at least one member selected from the group consisting of Ca-Mg-Zn based complex stabilizer, hydrotalcite, and fatty acid metallic soap. [0011] (4) A chlorinated rubber composition according to any one of (1) to (3) wherein the antioxidant is at least one member selected from the group consisting of phenol-based antioxidant, phosphorus-based antioxidant, and sulfur-based antioxidant. [0012] (5) A hose comprising a rubber layer and a reinforcement layer adjacent to the rubber layer formed by using the chlorinated rubber composition of any one of (1) to (4). Effects of the Invention [0013] As described below, the present invention is capable of providing a chlorinated rubber composition which can be used in producing a hose exhibiting excellent resistance to degradation by zinc together with the sufficient physical properties such as resistance to thermal aging, oil resistance, and adhesion, as well as a hose produced by using such chlorinated rubber composition for the rubber layer. Brief Description of the Drawings [0014] FIG. 1 is a perspective view showing an embodiment of the hose according to the present invention. FIG. 2 shows views taken by a microscope used in evaluating the rubber compositions (the vulcanized rubber sheets) produced in Comparative Example 1 and Example 10 for their resistance to degradation by zinc. FIG. 3 shows views taken by a microscope used in evaluating the rubber compositions (the vulcanized rubber sheets) produced in Comparative Example 15 and Example 24 for their resistance to degradation by zinc. Description of symbols [0015] 1 Hose 2 Rubber inner layer 3 Reinforcement layer 4 Rubber outer layer Best Mode for Carrying out the Invention [0016] Next, the present invention is described in further detail. The chlorinated rubber composition of the present invention (hereinafter simply referred to as "the rubber composition of the present invention") comprises a chlorinated rubber, a metal deactivator, an acid acceptor, and an antioxidant. The metal deactivator is included at a content of at least 0.3 parts by weight in relation to 100 parts by weight of the chlorinated rubber. The acid acceptor is included at a content of at least 1 parts by weight in relation to 100 parts by weight of the chlorinated rubber. The antioxidant is included at a content of 0.1 to 10 parts by weight in relation to 100 parts by weight of the chlorinated rubber. Next, the chlorinated rubber, the metal deactivator, the acid acceptor, and the antioxidant included in the rubber composition of the present invention are described in detail. [0017] The chlorinated rubber is an rubber elastomer produced by chlorinating and chlorosulfonating a powder or particles of a polyolefin such as polyethylene or polypropylene; a styrene- butadiene block copolymer; or a styrene-isoprene block copolymer. [0018] In the present invention, the method used in the chlorination or chlorosulfonation is not particularly limited, and any method known in the art may be used for the chlorination and chlorosulfonation. [0019] In the present invention, chlorine (CI) content in the chlorinated rubber is not particularly limited. However, the chlorine content is preferably in the range of 20 to 50 % by weight, and more preferably 25 to 45 % by weight in view of the balance between workability of the unvulcanized rubber composition and properties of the vulcanized rubber composition such as tensile properties, oil resistance, heat resistance, and cold resistance. [0020] Preferable examples of such chlorinated rubbers include chlorinated polyethylene (CM) such as those prepared by chlorinating polyethylene, chlorosulfonated polyethylene (CSM) prepared by simultaneously chlorinating and chlorosulfonating polyethylene, and chlorinated ethylene-a-olefin copolymer rubber. Among these, the preferred are CM and CSM in view of favorable weatherability, ozone resistance, heat resistance, flame retardancy, oil resistance, and the like. [0021] Exemplary chlorinated rubbers which may be used in the present invention include commercially available products such as chlorinated polyethylene (product name: Tyrin CM0136, chlorine content: 36%, manufactured by Dupont Dow Elastmer), chlorinated polyethylene (product name: Elaslen 301AE, chlorine content: 32%, manufactured by Showa Denko K.K.), chlorinated polyethylene (product name: Weipren CM6235, chlorine content: 35%, manufactured by Yaxing Chemical), chlorosulfonated polyethylene (product name: Hypalon40S, chlorine content: 35%, manufactured by Dupont), and chlorosulfonated polyethylene (product name: TOSO-CSM CN-530, chlorine content: 35%, manufactured by Tosoh). [0022] In the present invention, the chlorinated rubber may be a mixture of two or more chlorinated rubbers mixed at an arbitrary ratio. Also, the chlorinated rubber may optionally include a rubber other than the chlorinated rubber (hereinafter referred to as "other rubbers") to the extent that does not adversely affect the object of the present invention. Examples of such other rubbers include acrylic rubber (ACM), ethyl acrylate-ethylene copolymer (AEM), ethyl acrylate-acrylonitrile copolymer (ANM), ethylene-propylene- diene terpolymer (EPDM), ethylene-propylene copolymer (EPM), ethylene-vinyl acetate copolymer (EVM), fluorinated rubber (FKM), fully hydrogenated nitrile rubber (NBM), epichlorohydrin rubber (CO), ethylene oxide-epichlorohydrin copolymer (ECO), dimethyl silicone rubber (MQ), acrylate butadiene rubber (ABR), butadiene rubber (BR), chloroprene rubber (CR), natural rubber (NR), epoxidated natural rubber (ENR), isoprene rubber (IR), acrylonitrile-isoprene rubber (NIR), butyl rubber (IIR), hydrogenated nitrile rubber (HNBR), nitrile rubber (NBR), styrene butadiene rubber (SBR), styrene- isoprene-butadiene rubber (SIBR), carboxylated butadiene rubber (XBR), carboxylated nitrile rubber (XNBR), carboxylated styrene butadiene rubber (XSBR), brominated butyl rubber (BUR), chlorinated butyl rubber (CIIR), polysulfide rubber (OT), and polyester urethane (AU), which may be used alone or in combination of two or more. Such rubber other than the chlorinated rubber used by blending with the chlorinated rubber may be used at an amount up to 30% by weight in relation to the total weight after the blending. [0023] The metal deactivator is a chelating agent having the function of chelating the metal ion to prevent the metal ion from acting as the catalyst. In the present invention, the zinc that has moved into the chlorinated rubber is chelated to thereby suppress the reaction between the hydrogen chloride generated by the dechlorination of the chlorinated rubber and the zinc, and to further prevent the dechlorination induced by the catalytic function of the zinc chloride (ZnCl2) produced by such reaction between the hydrogen chloride and the zinc. [0024] The metal deactivators which may be used in the present invention include heavy metal deactivators known in the art such as benzotriazole derivatives, oxalic acid derivatives, salicylic acid derivatives, hydrazide derivatives, hydroxybenzoic acid anilide derivatives, and sulfur-containing phosphites disclosed in "Manual on Additives for Rubbers and Plastics, New Edition" (Rubber Digest), pages 90 to 91. and "Developments in the Macromolecullar Additives" (The Nikkan Kogyo Shimbun, Ltd.), pages 76 to 85. Exemplary metal deactivators include 1,2,3-benzotriazole, 3-(N-salicyloyl)amino-1,2,4-triazole, disalicyloylhydrazide decamethylenedicarboxylic acid, N,N'-bis[3-[3,5-di-t-butyl-4- hydroxyphenyl]propionyl]hydrazine, 2,2' -oxamidebis[ethyl-3- (3,5-t-butyl-4-hydroxyphenyl)propionate], bisbenzylidenehydrazide oxalic acid, bis(2- phenoxypropionylhydrazide) isophthalic acid, 2,4,6-triamino- 1,3,5-triazine, 3,9-bis[2-(3,5-diamino-2,4,6-triazaphenyl)- ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, ethylenediaminetetraacetic acid, alkali metal (such as Li, Na, or K) salt of ethylenediaminetetraacetic acid, and tris[2-t- butyl-4-thio(2' -methyl-4' -hydroxy-5' -t-butyl)phenyl-5-methyl]- phenyl phosphite, which may be used alone or in combination of two or more. [0025) Among these, the preferred is bisbenzylidenehydrazide oxalic acid in view of suppressing the reaction between the hydrogen chloride generated by the dechlorination of the chlorinated rubber and the zinc. [0026] Examples of the commercially available metal deactivator which may be used in the present invention include oxalic acid bisbenzylidene hydrazide (product name: Inhibitor OABH, manufactured by Eastman), 3-(N-salicyloyl)amino-l,2,4-triazole (product name: Adeka Stab CDA-1 and CDA-1M, manufactured by ADEKA), decamethylene dicarboxylic disalicyloylhydrazide (product name: Adeka StabCDA-6, manufactured by ADEKA), N,N'- bis[3-[3,5-di-t-butyl-4-hydroxyphenyl]propionyl]hydrazine (product name: Irganox MD 1024, manufactured by Ciba Geigy), . and 2,2'-oxamide bis[ethyl-3-(3,5-t-butyl-4- hydroxyphenyl)propionate] (product, name: Naugard XL-1, manufactured by Shiraishi Calcium). [0027] In the present invention, the metal deactivator is incorporated at an amount of at least 0.3 parts by weight, preferably at 0.5 to 20 parts by weight, and more preferably 1 to 10 parts by weight in relation to 100 parts by weight of the chlorinated rubber. [0028) The acid acceptor is an additive (stabilizer) which stabilizes the polymer by reacting with the halogenated hydrogen (acid) generated by thermal decomposition or the like of the polymer. In the present invention, hydrogen chloride which is formed in the course of the dechlorination of the chlorinated rubber is trapped to thereby suppress formation of the zinc chloride (ZnCl2) which plays the role of catalyst in the dechlorination. [0029] Exemplary acid acceptors include Ca-Mg-Zn, Ba-Mg-Zn, Ca- Zn-Sn, and Ba-Zn based complex stabilizer; hydrotalcites; fatty acid metallic soaps; inorganic acid salts; and organotin compounds; which may be used alone or in combination of two or more. Among these, the preferred are Ca-Mg-Zn, Ba-Mg-Zn, Ca- Zn-Sn, and Ba-Zn based complex stabilizer; fatty acid metallic soaps; and hydrotalcites (and in particular, basic carbonate of Mg and/or Al) since they are free from heavy metals such as lead that cause environmental pollution, and they have excellent thermal stability. Typical fatty acid metallic soaps are alkali metal salts of fatty acid and the preferable examples include lithium salt, potassium salt, and sodium salt of a saturated fatty acid containing 1 to 18 carbon atoms, an unsaturated fatty acid containing 3 to 18 carbon atoms, an aliphatic dicarboxylic acid, and an aromatic carboxylic acid. [0030] In the present invention, the acid acceptor may preferably comprise a combination of hydrotalcite and a fatty acid metallic soap since they are synergetic in trapping the hydrogen chloride. [0031] Exemplary acid acceptors which may be used in the present invention include commercially available products such as sodium stearate (product name: SS-40N, manufactured by Kao), potassium stearate (product name: Nonsoul SK-1, manufactured by NOF Corporation), calcium stearate (product name: calcium stearate G, manufactured by NOF Corporation), Ca-Mg-Zn based complex stabilizer (product name: Adeka Stab RUP 110, manufactured by ADEKA), Ba-Zn based complex stabilizer (product name: Adeka Stab RUP 14, manufactured by ADEKA), and hydrotalcites (product names: DHT-4A, DHT-4A-2, DHT-4C, KW- 2000, KW-2100, and KW-2200, manufactured by Kyowa Chemical Industry Co.,Ltd.). [0032] In the present invention, the acid acceptor may be included at a content of at least 1 parts by weight, preferably at 1 to 40 parts by weight, and more preferably at 1 to 20 parts by weight in relation to 100 parts by weight of the chlorinated rubber. [0033] The antioxidant is blended for the purpose of suppressing the oxidation chain reaction of the rubber, and in the present invention, the antioxidant is used for the purpose of suppressing generation of radicals in the initial stage of the chlorinated rubber degradation (for example, the polymer radical, polymer hydroperoxide radical, and the like as described below), trapping the polymer radical, and suppressing the binding (curing) of the polymer radical. [0034] Exemplary antioxidants include phenol-based antioxidants, phosphorus-based antioxidant, and sulfur-based antioxidants. [0035) Examples of the phenol-based antioxidants include tetrakis [methylene-3(3',5' di-t-butyl-4- hydroxyphenyl)propionate]methane, n-octadecyl-3-(4'-hydroxy- s', 5' -di-t-butylphenyl)propionate, 3,9-bis[2-{3-(3-t-butyl-4- hydroxy-5-methylphenyl) propionyloxy}-1,1-dimethyl ethyl]- 2,4,8,10-tetraoxaspiro[5,5]undecane, triethylene glycol-N-bis- 3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate, 1,6- hexanediol bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], and 2,2-thio bis-diethylene bis[3-(3,5-di-t-butyl-4- hydroxyphenyl)propionate], which may be used alone or in combination of two or more. [0036] Exemplary phosphorus-based antioxidants include tris (nonylphenyl)phosphite, tris(2,4-di-t- butylphenyl)phosphite, distearyl pentaerythritoldiphosphite, bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite, bis(2,4-di-t-butyl-6-methylphenyl) pentaerythritol diphosphite, bis (2, 6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis{2,4-dicumylphenyl)pentaerythritol diphosphite, tetrakis (2,4-di-t-butylphenyl)-4,4' -diphenylene diphosphonite, 2,2' -methylenebis (4, 6-di-t-butylphenyl) 2-ethylhexyl phosphite, 2,2' -ethylidene bis(4,6-di-t-butylphenyl) fluorophosphite, bis (2, 4-di-t-butyl-6-methylphenyl) ethylphosphite, 2- (2,4, 6- tri-t-butylphenyl) -5-ethyl-5-butyl-l, 3,2-oxaphosholinane, and 2,2', 2" -nitrilo[triethyl-tris (3,3', 5,5' -tetra-t-butyl-1,1' - biphenyl-2,2'-diyl) phosphite, which may be used alone or in combination of two or more. [0037] Exemplary sulfur-based antioxidants include dilauryl 3, 3'-thiodipropionate, tridecyl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3'- thiodipropionate, lauryl stearyl 3,3'-thiodipropionate, neopentanetetrayltetrakis(3-lauryl thiopropionate), and bis[2- methyl-4- (3-n-Ci2-n alkyl-thiopropionyloxy) -5-t-butylphenyl] sulfide, which may be used alone or in combination of two or more. [0038] Among these, the preferred are phenol-based antioxidants in view of the improved stabilization and antioxidant effects during the processing. [0039] Examples of the commercially available antioxidants which may be used in the present invention include tetrakis [methylene-3 (3', 5' -di-t-butyl-4-hydroxyphenyl)propionate] methane (product name: Irganox 1010, manufactured by Ciba Geigy), n-octadecyl-3-(4'-hydroxy-3',5'-di-t- butylphenyl)propionate (product name: Adeka Stab AO-50, manufactured by ADEKA), tris(nonylphenyl) phosphite (product name: Adeka Stab 1178, manufactured by ADEKA), and dilauryl 3,3'-thiodipropionate (product name: Antiox L, manufactured by NOF Corporation). [0040] In the present invention, the antioxidant may be included at a content of 0.1 to 10 parts by weight, preferably at 0.5 to 5 parts by weight, and more preferably at 0.5 to 3 parts by weight in relation to 100 parts by weight of the chlorinated rubber. [0041] The rubber composition of the present invention contains a predetermined amount of each of the chlorinated rubber, the metal deactivator, the acid acceptor, and the antioxidant in relation to the chlorinated rubber, and this enables production of a hose having excellent resistance to degradation by zinc together with sufficient physical properties such as resistance to thermal aging, oil resistance, and adhesion. The inventors of the present invention estimate that the resistance to degradation by zinc is realized by the following reasons. [0042] Presumably, the main reason for the degradation of the chlorinated rubber by zinc is hardening and embrittlement of the polymer by zinc chloride (ZnCl2) which is formed by the reaction between the chlorine and the zinc. More specifically, the degradation of the chlorinated rubber by zinc is postulated to involve the following elementary reactions (1) to (4). [0043] (1) Dechlorination The chlorinated polymer under the influence of heat is postulated to undergo the dechlorination represented by the following reaction scheme: wherein RC1 is the chlorinated part of the chlorinated rubber, RH is the polyolefin part of the chlorinated rubber, R- represents polymer radical, and CI- represents chlorine radical. [0044] (2) Formation of zinc chloride Presumably, the hydrogen chloride formed by the dechlorination formes zinc chloride (ZnCl2) by reacting with zinc or zinc oxide by the reaction scheme: 2HC1 + Zn → ZnCl2 + H2 2HC1 + ZnO → ZnCl2 + H2O [0045] (3) Chain reaction of dechlorination and radical formation in the presence of zinc chloride (ZnCl2) The thus formed ZnCl2 is a Louis acid catalyst which functions as a catalyst in the dechlorination of the halogenated alkyl, and therefore, it should promote dechlorination of the chlorinated rubber and formation of polymer radical. [Chemical formula 1] wherein ROO- is polymer hydroperoxide radical, and ROOH is polymer hydroperoxide. [0046] (4) Hardening Mutual binding (hardening) or crosslinking of the thus formed polymer radical results in the increase in the crosslinking density, and the polymer becomes even more brittle. The embrittled chlorinated rubber is subject to crack formation and breakage by the externally applied stress, thereby experiencing the degradation by zinc. R- + R∙ → R-R ROO- + R∙ → ROOR [0047] Based on such estimation of the mechanism of the degradation by zinc of the chlorinated polymer, the inventors of the present invention arrived at the following integral countermeasure for such zinc degradation of the chlorinated polymer. (A) Trapping of chlorine (countermeasure for dechlorination and ZnCl2 formation) Formation of the ZnCl2 which is the catalyst for the dechlorination can be suppressed if the chlorine that had left the chlorinated rubber could be trapped without delay. (B) Trapping of zinc (countermeasure for ZnCl2 formation) Formation of the ZnCl2, and hence, dechlorination can be suppressed if zinc in the chlorinated rubber could be stabilized by chelation. (C) Trapping of radical (countermeasure for hardening) Mutual binding (hardening) of the polymer radical, and hence, the embrittlement of the chlorinated rubber can be suppressed if the polymer radical that had been formed could be eliminated. [0048] Incorporation of the metal deactivator as described above at a predetermined amount should prevent dechlorination of the chlorinated rubber by chelation of the zinc that has moved into the chlorinated rubber; suppress the reaction between the hydrogen chloride generated by the dechlorination of the chlorinated rubber and the zinc; and prevent the dechlorination of the chlorinated rubber promoted by the zinc chloride (ZnCl2) generated in such dechlorination acting as a catalyst (see (B), above). Incorporation of the acid acceptor at a predetermined amount is believed to enable trapping of the hydrogen chloride generated in the course of the dechlorination of the chlorinated rubber to thereby suppress the promotion of the decomposition of the chlorinated rubber and the generation of the zinc chloride (ZnCl2) by the escaped hydrogen chloride (see (A), above). Furthermore, incorporation of the antioxidant at a predetermined amount is believed to suppress generation of the radicals generated in the initial stage of the chlorinated rubber deterioration, and facilitate trapping of the polymer radical as well as suppression of the mutual binding of the polymer radical (hardening) (see (C), above). [0049] In the present invention, resistance to degradation by zinc was evaluated as described below and in the Examples. First, the vulcanized sheet comprising the rubber composition of the present invention having a thickness of 2 mm was brought in contact with a zinc sheet, and after compressing the laminate by 20%, the sheet was left in an oven at 150°C for 72 hours. The laminate was allowed to cool to room temperature, and the vulcanized sheet was separated from the zinc sheet. The vulcanized sheet was bent at an angle of 180°C by using a clip, and the surface on the side that had been in contact with the zinc sheet was checked for the generation of cracks by using a microscope (at a magnification of 100), The resistance to degradation by zinc was evaluated to be acceptable when no cracks were found on the surface. [0050] If desired, the rubber composition of the present invention may optionally contain additives such as a filler, reinforcing agent, antiaging agent, vulcanizer, vulcanization accelerator, vulcanization aid, plasticizer, pigment (dye), tackifier, lubricant, dispersant, and processing aid at an amount that does not adversely affect the object of the present invention. [0051] The method used for producing the rubber composition of the present invention is not particularly limited, and in an exemplary method, the chlorinated rubber, the metal deactivator, the acid acceptor, and the antioxidant are mixed (kneaded) by an open roll, kneader, extruder, universal agitator, batch kneader, or the like. The temperature used for the mixing of the components is not particularly limited since the temperature is determined by the apparatus used for the mixing. When a batch kneader is used for the mixing, the mixing is preferably conducted at a temperature of 50 to 160°C, and more preferably at 50 to 120°C. Also, the time used for the mixing is not particularly limited since the temperature is determined by the apparatus used for the mixing. In the case of a batch kneader, the mixing is preferably accomplished in about 1 to 15 minutes. [0052] The hose of the present invention is a hose comprising the rubber layer(s) formed by using the rubber composition of the present invention and a reinforcement layer adjacent to the rubber layer(s). [0053] A preferred embodiment of the hose of the present invention is shown in FIG. 1. FIG. 1 is a perspective view in which the layers of the hose are partially cut away. As shown in FIG. 1, hose 1 comprises a rubber inner layer 2 as an inner tube overlaid with a reinforcement layer 3 and a rubber outer layer 4 as an outer tube. [0054] Next, the rubber layers (the rubber inner layer and the rubber outer layer) and the reinforcement layer constituting the hose of the present invention are described in detail. [0055] The rubber layers are the layers adjacent to the reinforcement layer, and the hose of the present invention has the rubber inner layer and the rubber outer layer. In the present invention, the rubber inner layer or the rubber outer layer in contact with metal parts are formed by using the rubber composition of the present invention in order to improve resistance to degradation by zinc when such rubber layer became in contact with a zinc-plated joint and other metal parts. Even if the zinc plating is covered by another plating layer of chromium or the like, the rubber composition of the present invention may be used if the exposed zinc may become in contact with the chlorinated rubber. By forming the rubber layers using the rubber composition of the present invention, a hose having an improved resistance to degradation by zinc can be produced even if the reinforcement layer was formed by using a fiber material or a metal material such as a steel wire for the reinforcement layer. [0056] In the present invention, the rubber inner layer may have a thickness of 0.2 to 4.0 mm, and more preferably 0.5 to 2.0 mm. Similarly, the rubber outer layer may have a thickness of 0.2 to 4.0 mm, and more preferably 0.5 to 2.0 mm. [0057] The reinforcement layer is the layer formed in the exterior of the rubber inner layer as described above for the purpose of maintaining the strength of the product. In the present invention, the reinforcement layer may comprise either a braid or a coil, and the material used for the reinforcement layer is not particularly limited. Exemplary preferable materials include polyester fibers, polyamide fibers, alamid fibers, vinilon fibers, rayon fibers, PBO (polyparaphenylene benzobisoxazole) fibers, polyallylate fibers, and polyketone fibers. The reinforcement layer may also comprise a metal reinforcement layer, and the metal materials used for such reinforcement layer is also not limited. Exemplary preferable metal materials include hard steel wire (brass plated wires). Among these, the preferred are polyester fibers and polyamide fibers in view of the improved size stability, heat resistance, and fatigue resistance. [0058] The method used for producing the hose of the present invention comprising the rubber layer and the reinforcement layer is not particularly limited, and any method known in the art can be used in producing such hose of the present invention. In an exemplary process, the rubber inner layer, the reinforcement layer, and the rubber outer layer may be disposed in this order on a mandrel, and these layers may be adhered by press vulcanization, vapor vulcanization, oven vulcanization (hot air vulcanization), or hot water vulcanization conducted for 30 to 180 minutes under the conditions of 140 to 190°C. Examples [0059] Next, the rubber composition of the present invention is described in detail by referring to the Examples which by no means limit the scope of the present invention. [0060] (Examples 1 to 14 and Comparative Examples 1 to 14) The components shown in Table 1 were blended at the ratio (part by weight) shown in Table 1 to prepare the rubber composition. More specifically, the components shown in Table 1 except for the crosslinking agent 1 were kneaded in Banbury mixer (3.4 liters) for 4 minutes, and the content was removed from the mixer when the temperature reached 140°C. The master batch was thereby obtained. Next, the crosslinking agent 1 was kneaded with the thus obtained master batch by open rolls to prepare the rubber composition. The thus obtained rubber compositions were evaluated for their tensile properties after vulcanization, resistance to thermal aging, oil resistance, adhesion, and resistance to degradation by zinc by the procedure as described below. The results are shown in Table 1. [0061] (1) Tensile properties The resulting rubber composition was vulcanized for 60 minutes by using a press molding machine at 157°C under the surface pressure of 3.0 MPa to produce a vulcanized sheet having a thickness of 2 mm. JIS No. 3 dumbbell test pieces were blanked from this sheet, and tensile test was conducted in accordance with JIS K6251-2004 at a tensile speed of 500 mm/minute to measure tensile strength (TB)[MPa], elongation at break (EB)[%], and 50% modulus {M50) [MPa] at room temperature. [0062] (2) Resistance to thermal aging The same vulcanized sheet having a thickness of 2 mm as one used in measuring the tensile properties was left in an oven at 150°C for 72 hours, and the sheet was measured for the elongation at break (EB) [%] in accordance with JIS K6251-2004. [0063] (3) Oil resistance The same vulcanized sheet having a thickness of 2 mm as one used in evaluating the tensile properties was immersed in a test oil (IRM 903, manufactured by Japan Sun Oil Corporation., Ltd.) at 150°C for 72 hours, and elongation "at break (EB) [%] after the immersion was measured by JIS K6258- 2003. [0064] (4) Adhesion A test piece in the shape of a hose comprising a rubber outer layer comprising the thus obtained rubber composition and a reinforcement layer comprising the nylon 66 fibers (comprising 3 twisted 1000 dtex strands) which had been dipped in RFL solution was prepared by the procedure as described below. The nylon 66 fibers were braided on a mandrel having an outer diameter of 34 mm to form the reinforcement layer. Next, an unvulcanized sheet having a thickness of 2.5 mm was formed by using the products of Examples 1 to 14 and Comparative Examples 1 to 14, and this sheet was adhered on the reinforcement layer. This test piece was then vulcanized to prepare the vulcanized test piece. The rubber outer layer was peeled off the hose-shaped test piece at a peeling speed of 50 mm/min to measure the adhesion strength (unit: N per width of 25 mm). [0065] (5) Resistance to degradation by zinc The same vulcanized sheet having a thickness of 2 mm as one used in measuring the tensile properties was brought in contact with a zinc sheet, and after compressing the laminate by 20%, the sheet was left in an oven at 150°C for 72 hours. The laminate was allowed to cool to room temperature, and the vulcanized sheet was separated from the zinc sheet. The vulcanized sheet was bent at an angle of 180°C by using a clip, and the surface on the side that had been in contact with the zinc sheet was checked for the generation of cracks by using a microscope (at a magnification of 100). When cracks were found, their average length was measured. [0066] [Table 1] [0067] [Table 2] [0068] [Table 3] [0069} The components indicated in Table 1 are as described below. - Chlorinated rubber 1: chlorinated polyethylene (product name: Tyrin CM0136, chlorine content: 36%, manufactured by Dupont Dow Elastmer) - Chlorinated rubber 2: chlorosulfonated polyethylene (product name: Hypalon 40S, chlorine content: 35%, manufactured by Dupont) - EPDM: ethylene-propylene-diene terpolymer (product name: MITSUI EPT 4070, ethylene content: 56%, ethylidene norbornene content: 8%, manufactured by Mitsui Petrochemical Industries) - NBR: nitrile rubber (product name: Nipol 1041, nitrile content: 40.5%, Mooney viscosity ML (1+4 at 100°C): 82.5, manufactured by ZEON Corporation) - AEM: methyl acrylate-ethylene copolymer (product name: VAMAC DP, Mooney viscosity ML (1+4 at 100°C): 22, manufactured by Mitsui Du-Pont Polychemical) - Magnesium oxide: kyowamag 150 (specific surface area 150 m2/g), manufactured by Kyowa Chemical Industry Co.,Ltd. [0070] - Metal deactivator 1: bisbenzylidenehydrazide oxalic acid (product name: Inhibitor OABH, manufactured by Eastman) - Metal deactivator 2: N,N+-bis[3-[3,5-di-t-butyl-4- hydroxyphenyl]propionyl]hydrazine (product name: Irganox MD 1024, manufactured by Ciba-Geigy) - Metal deactivator 3: 2,2'-oxamidebis[ethyl 3-(3,5-t- butyl-4-hydroxyphenyl)propionate] (product name: Naugard XL-1, manufactured by Shiraishi Calcium) - Metal deactivator 4: disalicyloylhydrazide decamethylene dicarboxylic acid (product name: Adeka Stab CDA- 6, manufactured by ADEKA) - Acid acceptor 1: Ca-Mg-Zn based complex stabilizer (product name: Adeka Stab RUP 110, manufactured by ADEKA) - Acid acceptor 2: hydrotalcite (product name: DHT-4A, manufactured by Kyowa Chemical Industry Co.,Ltd) - Acid acceptor 3: sodium stearate (product name: SS-40N, manufactured by Kao) - Antioxidant 1: tetrakis [methylene-3(3',5'di-t-butyl-4- hydroxyphenyl)propionate] methane (product name: Irganox 1010, manufactured by Ciba-Geigy) - Antioxidant 2: tris(nonylphenyl)phosphite (product name: Adeka Stab 1178, manufactured by ADEKA) - Antioxidant 3: dilauryl 3,3'-thiodipropionate (product name: Antiox L, manufactured by NOF Corporation) [0071] - Carbon black 1: SRF grade carbon black, manufactured by Asahi Carbon - Processing aid: hydrophilic higher fatty acid ester (product name: Struktol WB212, manufactured by Schill & Seilacher GMBH & CO.) - Crosslinking aid: pentaerythritol (product name: Neulizer P, manufactured by The Nippon Synthetic Chemical Industry Co., Ltd.) - Plasticizer: isononyl trimellitate (product name: C-9N, manufactured by ADEKA) - Co-crosslinking agent: triallyl isocyanurate (product name: TAIC, manufactured by Nippon Kasei) - Crosslinking agent 1: dicumyl peroxide (product name: Percumyl D-40, manufactured by NOF corporation) [0072] (Example 15 to 26 and Comparative Example 15 to 29) The components shown in Table 2 were blended at the ratio (part by weight) shown in Table 2 to prepare the rubber composition. More specifically, the components shown in Table 2 except for the crosslinking agent 2 were kneaded in Banbury mixer (3.4 liters) for 4 minutes, and the content was removed from the mixer when the temperature reached 140°C. The master batch was thereby obtained. Next, the crosslinking agent 2 was kneaded with the thus obtained master batch by open rolls to prepare the rubber composition. The thus obtained rubber compositions were evaluated for their tensile properties after vulcanization, resistance to thermal aging, oil resistance, adhesion, and resistance to degradation by zinc by the procedure as described above. The results are shown in Table 2. [0074][Table 5] [0075] The components shown in Table 2 which are different from those shown in Table 1 are as described below. - Carbon black 2: FEF grade carbon black, manufactured by Nippon Steel Chemical Carbon Co., Ltd. - Crosslinking agent 2: N,N'-m-phenylene dimaleimide (product name: HVA-2, manufactured by Dupont) [0076] As evident from the results shown in Tables 1 and 2, the rubber compositions prepared in Examples 1 to 26 containing the metal deactivator, the acid acceptor, and the antioxidant at the predetermined amount in relation to the chlorinated rubber are rubber compositions which can be used in producing a hose which has excellent resistance to degradation by zinc simultaneously with the physical properties such as resistance to thermal aging, oil resistance and adhesion, in contrast to the rubber compositions prepared in Comparative Examples 1 to 29 not containing such components at the predetermined amount. [0077] The picture taken by a microscope in the evaluation of the rubber compositions (the vulcanized rubber sheets) prepared in Comparative Example 1 and Example 10 for their resistance to degradation by zinc are shown in FIG. 2. The picture taken by a microscope in the evaluation of the rubber compositions (the vulcanized rubber sheets) prepared in Comparative Example 15 and Example 24 are also shown in FIG. 3. As evident from FIGS. 2 and 3, cracks were confirmed in the vulcanized rubber sheets prepared in Comparative Examples 1 and 15 while no cracks were confirmed in the vulcanized rubber sheets prepared in Examples 10 and 24. CLAIMS 1. A chlorinated rubber composition comprising a chlorinated rubber, a metal deactivator, an acid acceptor, and an antioxidant, wherein the metal deactivator is included at a content of at least 0.3 parts by weight in relation to 100 parts by weight of the chlorinated rubber, the acid acceptor is included at a content of at least 1 parts by weight in relation to 100 parts by weight of the chlorinated rubber, and the antioxidant is included at a content of 0.1 to 10 parts by weight in relation to 100 parts by weight of the chlorinated rubber. 2. A chlorinated rubber composition according to claim 1 wherein the metal deactivator is at least one member selected from the group consisting of 1,2,3-benzotriazole, 3-(N- salicyloyl)amino-1,2,4-triazole, decamethylenedicarboxylic acid disalicyloylhydrazide-, N,N' -bis [3- (3,5-di-t-butyl-4- hydroxyphenyl)propionyl]hydrazine, 2,2'-oxamidebis[ethyl 3- (3,5-t-butyl-4-hydroxyphenyl)propionate], oxalic acid bisbenzylidenehydrazide, isophthalic acid bis(2-phenoxy propionylhydrazide), 2,4, 6-triamino-l,3,5-triazine, ethylenediaminetetraacetic acid, alkali metal salt of ethylenediaminetetraacetic acid, tris[2-t-butyl-4-thio(2'- methyl-4'-hydroxy-5'-t-butyl) phenyl-5-methyl]-phenyl phosphite, and 3,9-bis[2-(3,5-diamino-2,4,6-triazaphenyl) ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane. 3. A chlorinated rubber composition according to claim 1 or 2 wherein the acid acceptor is at least one member selected from the group consisting of Ca-Mg-Zn based complex stabilizer, hydrotalcite, and fatty acid metallic soap. 4. A chlorinated rubber composition according to any one of claims 1 to 3 wherein the antioxidant is at least one member selected from the group consisting of phenol-based antioxidant, phosphorus-based antioxidant, and sulfur-based antioxidant. 5. A hose comprising a rubber layer and a reinforcement layer adjacent to the rubber layer formed by using the chlorinated rubber composition of any one of claims 1 to 4. A chlorinated rubber composition including a chlorinated rubber, a metal deactivator, an acid acceptor, and an antioxidant respectively at a particular amount is provided. The chlorinated rubber composition is capable of providing a chlorinated rubber composition which can be used in producing a hose exhibiting excellent resistance to degradation by zinc together with the sufficient physical properties such as resistance to thermal aging, oil resistance, and adhesion, as well as a hose produced by using such chlorinated rubber composition for the rubber layer.

Full Text

DESCRIPTION
CHLORINATED RUBBER COMPOSITION AND HOSE
Technical Field
[0001]
This invention relates to a chlorinated rubber
composition and a hose produced by using such chlorinated
rubber composition.
Background Art
[0002]
Chlorinated rubbers (for example, chlorinated
polyethylene rubbers and chlorosulfonated polyethylenes) have
excellent properties such as resistance to thermal aging, oil
resistance, cold resistance, weatherability, flame resistance,
and electric properties, and they are used as the molding
materials of various high pressure hoses as such as automobile
power stearing hoses; cable sheaths; gaskets; packings; and
other molded articles.
[0003]
Of such molding materials, the high pressure hoses
produced by using a chlorinated rubber for the rubber layer
should have sufficient resistance to degradation by zinc
because, when such hoses become in contact with a metal part,

and in particular, with zinc-plated joint at a high pressure
and a high temperature, the chlorinated rubber constituting
the rubber layer is rapidly and harshly degraded or hardened
with cracks formation in the rubber layer or embrittlement or
tearing of the rubber layer.
[0004]
As a technnique to solve such problems, patent document
1 discloses a composition for chlorinated polyethylene
crosslinked rubber comprising (a) 100 parts by weight of
chlorinated polyethylene, (b) 2 to 10 parts by weight of
organic peroxide, (c) 3 to 20 parts by weight of crosslinking
aid, and (d) 3 to 40 parts by weight of at least one acid
acceptor selected from hydrotalcites and zeolites (claim 1}.
[0005]
Patent document 1: JP 2001-226546 A
Disclosure of the Invention
Problems to be solved by the Invention
[0006]
However, the hose produced by using the composition for
a chlorinated polyethylene crosslinked rubber of JP 2001-
226546 A for the rubber layer was found to be insufficient in
the resistance to degradation by zinc despite its sufficient

physical properties such as resistance to thermal aging, oil
resistance, and adhesion.
In view of the situation as described above, an object
of the present invention is to provide a chlorinated rubber
composition which can be used in producing a hose exhibiting
excellent resistance to degradation by zinc together with the
sufficient physical properties such as resistance to thermal
aging, oil resistance, and adhesion. Another object of the
present invention is to provide a hose produced by using such
chlorinated rubber composition for the rubber layer.
Means to solve the Problems
[0007]
In order to solve the problems as described above, the
inventors of the present invention made an intensive study and
found that a hose exhibiting excellent resistance to
degradation by zinc together with the sufficient physical
properties such as resistance to thermal aging, oil resistance,
and adhesion can be produced by using a chlorinated rubber
composition containing a metal deactivator, an acid acceptor,
and an antioxidant respectively at a particular amount in
relation to the chlorinated rubber composition. The present
invention has been completed on the bases of such finding.

Accordingly, the present invention provides the
following (1) to (5):
[0008]
(1) A chlorinated rubber composition comprising a
chlorinated rubber, a metal deactivator, an acid acceptor, and
an antioxidant, wherein
the metal deactivator is included at a content of at
least 0.3 parts by weight in relation to 100 parts by weight
of the chlorinated rubber,
the acid acceptor is included at a content of at least 1
parts by weight in relation to.100 parts by weight of the
chlorinated rubber, and
the antioxidant is included at a content of 0.1 to 10
parts by weight in relation to 100 parts by weight of the
chlorinated rubber.
[0009]
(2) A chlorinated rubber composition according to (1)
wherein the metal deactivator is at least one member selected
from the group consisting of 1,2,3-benzotriazole, 3-(N-
salicyloyl)amino-1,2,4-triazole, decamethylenedicarboxylic
acid disalicyloylhydrazide, N,N'-bis[3-(3,5-di-t-butyl-4-
hydroxyphenyl)propionyl]hydrazine, 2,2'-oxamidebis[ethyl 3-
(3,5-t-butyl-4-hydroxyphenyl)propionate], oxalic acid
bisbenzylidenehydrazide, isophthalic acid bis(2-phenoxy

propionylhydrazide), 2,4,6-triamino-l,3,5-triazine,
ethylenediandnetetraacetic acid, alkali metal (such as Li, Na,
or K) salt of ethylenediandnetetraacetic acid, tris[2-t-butyl-
4-thio(2'-methyl-4' -hydroxy-5' -t-butyl) phenyl-5-methyl]-
phenyl phosphite, and 3,9-bis[2-(3,5-diamino-2,4,6-
triazaphenyl) ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane.
[0010]
(3) A chlorinated rubber composition according to (1) or
(2) wherein the acid acceptor is at least one member selected
from the group consisting of Ca-Mg-Zn based complex stabilizer,
hydrotalcite, and fatty acid metallic soap.
[0011]
(4) A chlorinated rubber composition according to any
one of (1) to (3) wherein the antioxidant is at least one
member selected from the group consisting of phenol-based
antioxidant, phosphorus-based antioxidant, and sulfur-based
antioxidant.
[0012]
(5) A hose comprising a rubber layer and a reinforcement
layer adjacent to the rubber layer formed by using the
chlorinated rubber composition of any one of (1) to (4).
Effects of the Invention
[0013]

As described below, the present invention is capable of
providing a chlorinated rubber composition which can be used
in producing a hose exhibiting excellent resistance to
degradation by zinc together with the sufficient physical
properties such as resistance to thermal aging, oil resistance,
and adhesion, as well as a hose produced by using such
chlorinated rubber composition for the rubber layer.
Brief Description of the Drawings
[0014]
FIG. 1 is a perspective view showing an embodiment of
the hose according to the present invention.
FIG. 2 shows views taken by a microscope used in
evaluating the rubber compositions (the vulcanized rubber
sheets) produced in Comparative Example 1 and Example 10 for
their resistance to degradation by zinc.
FIG. 3 shows views taken by a microscope used in
evaluating the rubber compositions (the vulcanized rubber
sheets) produced in Comparative Example 15 and Example 24 for
their resistance to degradation by zinc.
Description of symbols
[0015]
1 Hose

2 Rubber inner layer
3 Reinforcement layer
4 Rubber outer layer
Best Mode for Carrying out the Invention
[0016]
Next, the present invention is described in further
detail.
The chlorinated rubber composition of the present
invention (hereinafter simply referred to as "the rubber
composition of the present invention") comprises a chlorinated
rubber, a metal deactivator, an acid acceptor, and an
antioxidant.
The metal deactivator is included at a content of at
least 0.3 parts by weight in relation to 100 parts by weight
of the chlorinated rubber.
The acid acceptor is included at a content of at least 1
parts by weight in relation to 100 parts by weight of the
chlorinated rubber.
The antioxidant is included at a content of 0.1 to 10
parts by weight in relation to 100 parts by weight of the
chlorinated rubber.

Next, the chlorinated rubber, the metal deactivator, the
acid acceptor, and the antioxidant included in the rubber
composition of the present invention are described in detail.
[0017]

The chlorinated rubber is an rubber elastomer produced
by chlorinating and chlorosulfonating a powder or particles of
a polyolefin such as polyethylene or polypropylene; a styrene-
butadiene block copolymer; or a styrene-isoprene block
copolymer.
[0018]
In the present invention, the method used in the
chlorination or chlorosulfonation is not particularly limited,
and any method known in the art may be used for the
chlorination and chlorosulfonation.
[0019]
In the present invention, chlorine (CI) content in the
chlorinated rubber is not particularly limited. However, the
chlorine content is preferably in the range of 20 to 50 % by
weight, and more preferably 25 to 45 % by weight in view of
the balance between workability of the unvulcanized rubber
composition and properties of the vulcanized rubber
composition such as tensile properties, oil resistance, heat
resistance, and cold resistance.

[0020]
Preferable examples of such chlorinated rubbers include
chlorinated polyethylene (CM) such as those prepared by
chlorinating polyethylene, chlorosulfonated polyethylene (CSM)
prepared by simultaneously chlorinating and chlorosulfonating
polyethylene, and chlorinated ethylene-a-olefin copolymer
rubber.
Among these, the preferred are CM and CSM in view of
favorable weatherability, ozone resistance, heat resistance,
flame retardancy, oil resistance, and the like.
[0021]
Exemplary chlorinated rubbers which may be used in the
present invention include commercially available products such
as chlorinated polyethylene (product name: Tyrin CM0136,
chlorine content: 36%, manufactured by Dupont Dow Elastmer),
chlorinated polyethylene (product name: Elaslen 301AE,
chlorine content: 32%, manufactured by Showa Denko K.K.),
chlorinated polyethylene (product name: Weipren CM6235,
chlorine content: 35%, manufactured by Yaxing Chemical),
chlorosulfonated polyethylene (product name: Hypalon40S,
chlorine content: 35%, manufactured by Dupont), and
chlorosulfonated polyethylene (product name: TOSO-CSM CN-530,
chlorine content: 35%, manufactured by Tosoh).
[0022]

In the present invention, the chlorinated rubber may be
a mixture of two or more chlorinated rubbers mixed at an
arbitrary ratio.
Also, the chlorinated rubber may optionally include a
rubber other than the chlorinated rubber (hereinafter referred
to as "other rubbers") to the extent that does not adversely
affect the object of the present invention.
Examples of such other rubbers include acrylic rubber
(ACM), ethyl acrylate-ethylene copolymer (AEM), ethyl
acrylate-acrylonitrile copolymer (ANM), ethylene-propylene-
diene terpolymer (EPDM), ethylene-propylene copolymer (EPM),
ethylene-vinyl acetate copolymer (EVM), fluorinated rubber
(FKM), fully hydrogenated nitrile rubber (NBM),
epichlorohydrin rubber (CO), ethylene oxide-epichlorohydrin
copolymer (ECO), dimethyl silicone rubber (MQ), acrylate
butadiene rubber (ABR), butadiene rubber (BR), chloroprene
rubber (CR), natural rubber (NR), epoxidated natural rubber
(ENR), isoprene rubber (IR), acrylonitrile-isoprene rubber
(NIR), butyl rubber (IIR), hydrogenated nitrile rubber (HNBR),
nitrile rubber (NBR), styrene butadiene rubber (SBR), styrene-
isoprene-butadiene rubber (SIBR), carboxylated butadiene
rubber (XBR), carboxylated nitrile rubber (XNBR), carboxylated
styrene butadiene rubber (XSBR), brominated butyl rubber
(BUR), chlorinated butyl rubber (CIIR), polysulfide rubber

(OT), and polyester urethane (AU), which may be used alone or
in combination of two or more.
Such rubber other than the chlorinated rubber used by
blending with the chlorinated rubber may be used at an amount
up to 30% by weight in relation to the total weight after the
blending.
[0023]
The metal deactivator is a chelating agent having the
function of chelating the metal ion to prevent the metal ion
from acting as the catalyst. In the present invention, the
zinc that has moved into the chlorinated rubber is chelated to
thereby suppress the reaction between the hydrogen chloride
generated by the dechlorination of the chlorinated rubber and
the zinc, and to further prevent the dechlorination induced by
the catalytic function of the zinc chloride (ZnCl2) produced
by such reaction between the hydrogen chloride and the zinc.
[0024]
The metal deactivators which may be used in the present
invention include heavy metal deactivators known in the art
such as benzotriazole derivatives, oxalic acid derivatives,
salicylic acid derivatives, hydrazide derivatives,
hydroxybenzoic acid anilide derivatives, and sulfur-containing
phosphites disclosed in "Manual on Additives for Rubbers and
Plastics, New Edition" (Rubber Digest), pages 90 to 91. and

"Developments in the Macromolecullar Additives" (The Nikkan
Kogyo Shimbun, Ltd.), pages 76 to 85.
Exemplary metal deactivators include 1,2,3-benzotriazole,
3-(N-salicyloyl)amino-1,2,4-triazole, disalicyloylhydrazide
decamethylenedicarboxylic acid, N,N'-bis[3-[3,5-di-t-butyl-4-
hydroxyphenyl]propionyl]hydrazine, 2,2' -oxamidebis[ethyl-3-
(3,5-t-butyl-4-hydroxyphenyl)propionate],
bisbenzylidenehydrazide oxalic acid, bis(2-
phenoxypropionylhydrazide) isophthalic acid, 2,4,6-triamino-
1,3,5-triazine, 3,9-bis[2-(3,5-diamino-2,4,6-triazaphenyl)-
ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane,
ethylenediaminetetraacetic acid, alkali metal (such as Li, Na,
or K) salt of ethylenediaminetetraacetic acid, and tris[2-t-
butyl-4-thio(2' -methyl-4' -hydroxy-5' -t-butyl)phenyl-5-methyl]-
phenyl phosphite, which may be used alone or in combination of
two or more.
[0025)
Among these, the preferred is bisbenzylidenehydrazide
oxalic acid in view of suppressing the reaction between the
hydrogen chloride generated by the dechlorination of the
chlorinated rubber and the zinc.
[0026]
Examples of the commercially available metal deactivator
which may be used in the present invention include oxalic acid

bisbenzylidene hydrazide (product name: Inhibitor OABH,
manufactured by Eastman), 3-(N-salicyloyl)amino-l,2,4-triazole
(product name: Adeka Stab CDA-1 and CDA-1M, manufactured by
ADEKA), decamethylene dicarboxylic disalicyloylhydrazide
(product name: Adeka StabCDA-6, manufactured by ADEKA), N,N'-
bis[3-[3,5-di-t-butyl-4-hydroxyphenyl]propionyl]hydrazine
(product name: Irganox MD 1024, manufactured by Ciba Geigy), .
and 2,2'-oxamide bis[ethyl-3-(3,5-t-butyl-4-
hydroxyphenyl)propionate] (product, name: Naugard XL-1,
manufactured by Shiraishi Calcium).
[0027]
In the present invention, the metal deactivator is
incorporated at an amount of at least 0.3 parts by weight,
preferably at 0.5 to 20 parts by weight, and more preferably 1
to 10 parts by weight in relation to 100 parts by weight of
the chlorinated rubber.
[0028)

The acid acceptor is an additive (stabilizer) which
stabilizes the polymer by reacting with the halogenated
hydrogen (acid) generated by thermal decomposition or the like
of the polymer. In the present invention, hydrogen chloride
which is formed in the course of the dechlorination of the
chlorinated rubber is trapped to thereby suppress formation of

the zinc chloride (ZnCl2) which plays the role of catalyst in
the dechlorination.
[0029]
Exemplary acid acceptors include Ca-Mg-Zn, Ba-Mg-Zn, Ca-
Zn-Sn, and Ba-Zn based complex stabilizer; hydrotalcites;
fatty acid metallic soaps; inorganic acid salts; and organotin
compounds; which may be used alone or in combination of two or
more.
Among these, the preferred are Ca-Mg-Zn, Ba-Mg-Zn, Ca-
Zn-Sn, and Ba-Zn based complex stabilizer; fatty acid metallic
soaps; and hydrotalcites (and in particular, basic carbonate
of Mg and/or Al) since they are free from heavy metals such as
lead that cause environmental pollution, and they have
excellent thermal stability.
Typical fatty acid metallic soaps are alkali metal salts
of fatty acid and the preferable examples include lithium salt,
potassium salt, and sodium salt of a saturated fatty acid
containing 1 to 18 carbon atoms, an unsaturated fatty acid
containing 3 to 18 carbon atoms, an aliphatic dicarboxylic
acid, and an aromatic carboxylic acid.
[0030]
In the present invention, the acid acceptor may
preferably comprise a combination of hydrotalcite and a fatty

acid metallic soap since they are synergetic in trapping the
hydrogen chloride.
[0031]
Exemplary acid acceptors which may be used in the
present invention include commercially available products such
as sodium stearate (product name: SS-40N, manufactured by Kao),
potassium stearate (product name: Nonsoul SK-1, manufactured
by NOF Corporation), calcium stearate (product name: calcium
stearate G, manufactured by NOF Corporation), Ca-Mg-Zn based
complex stabilizer (product name: Adeka Stab RUP 110,
manufactured by ADEKA), Ba-Zn based complex stabilizer
(product name: Adeka Stab RUP 14, manufactured by ADEKA), and
hydrotalcites (product names: DHT-4A, DHT-4A-2, DHT-4C, KW-
2000, KW-2100, and KW-2200, manufactured by Kyowa Chemical
Industry Co.,Ltd.).
[0032]
In the present invention, the acid acceptor may be
included at a content of at least 1 parts by weight,
preferably at 1 to 40 parts by weight, and more preferably at
1 to 20 parts by weight in relation to 100 parts by weight of
the chlorinated rubber.
[0033]

The antioxidant is blended for the purpose of
suppressing the oxidation chain reaction of the rubber, and in
the present invention, the antioxidant is used for the purpose
of suppressing generation of radicals in the initial stage of
the chlorinated rubber degradation (for example, the polymer
radical, polymer hydroperoxide radical, and the like as
described below), trapping the polymer radical, and
suppressing the binding (curing) of the polymer radical.
[0034]
Exemplary antioxidants include phenol-based antioxidants,
phosphorus-based antioxidant, and sulfur-based antioxidants.
[0035)
Examples of the phenol-based antioxidants include
tetrakis [methylene-3(3',5' di-t-butyl-4-
hydroxyphenyl)propionate]methane, n-octadecyl-3-(4'-hydroxy-
s', 5' -di-t-butylphenyl)propionate, 3,9-bis[2-{3-(3-t-butyl-4-
hydroxy-5-methylphenyl) propionyloxy}-1,1-dimethyl ethyl]-
2,4,8,10-tetraoxaspiro[5,5]undecane, triethylene glycol-N-bis-
3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate, 1,6-
hexanediol bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],
and 2,2-thio bis-diethylene bis[3-(3,5-di-t-butyl-4-
hydroxyphenyl)propionate], which may be used alone or in
combination of two or more.
[0036]

Exemplary phosphorus-based antioxidants include
tris (nonylphenyl)phosphite, tris(2,4-di-t-
butylphenyl)phosphite, distearyl pentaerythritoldiphosphite,
bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite,
bis(2,4-di-t-butyl-6-methylphenyl) pentaerythritol diphosphite,
bis (2, 6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite,
bis{2,4-dicumylphenyl)pentaerythritol diphosphite,
tetrakis (2,4-di-t-butylphenyl)-4,4' -diphenylene diphosphonite,
2,2' -methylenebis (4, 6-di-t-butylphenyl) 2-ethylhexyl phosphite,
2,2' -ethylidene bis(4,6-di-t-butylphenyl) fluorophosphite,
bis (2, 4-di-t-butyl-6-methylphenyl) ethylphosphite, 2- (2,4, 6-
tri-t-butylphenyl) -5-ethyl-5-butyl-l, 3,2-oxaphosholinane, and
2,2', 2" -nitrilo[triethyl-tris (3,3', 5,5' -tetra-t-butyl-1,1' -
biphenyl-2,2'-diyl) phosphite, which may be used alone or in
combination of two or more.
[0037]
Exemplary sulfur-based antioxidants include dilauryl
3, 3'-thiodipropionate, tridecyl 3,3'-thiodipropionate,
dimyristyl 3,3'-thiodipropionate, distearyl 3,3'-
thiodipropionate, lauryl stearyl 3,3'-thiodipropionate,
neopentanetetrayltetrakis(3-lauryl thiopropionate), and bis[2-
methyl-4- (3-n-Ci2-n alkyl-thiopropionyloxy) -5-t-butylphenyl]
sulfide, which may be used alone or in combination of two or
more.

[0038]
Among these, the preferred are phenol-based antioxidants
in view of the improved stabilization and antioxidant effects
during the processing.
[0039]
Examples of the commercially available antioxidants
which may be used in the present invention include tetrakis
[methylene-3 (3', 5' -di-t-butyl-4-hydroxyphenyl)propionate]
methane (product name: Irganox 1010, manufactured by Ciba
Geigy), n-octadecyl-3-(4'-hydroxy-3',5'-di-t-
butylphenyl)propionate (product name: Adeka Stab AO-50,
manufactured by ADEKA), tris(nonylphenyl) phosphite (product
name: Adeka Stab 1178, manufactured by ADEKA), and dilauryl
3,3'-thiodipropionate (product name: Antiox L, manufactured by
NOF Corporation).
[0040]
In the present invention, the antioxidant may be
included at a content of 0.1 to 10 parts by weight, preferably
at 0.5 to 5 parts by weight, and more preferably at 0.5 to 3
parts by weight in relation to 100 parts by weight of the
chlorinated rubber.
[0041]
The rubber composition of the present invention contains
a predetermined amount of each of the chlorinated rubber, the

metal deactivator, the acid acceptor, and the antioxidant in
relation to the chlorinated rubber, and this enables
production of a hose having excellent resistance to
degradation by zinc together with sufficient physical
properties such as resistance to thermal aging, oil resistance,
and adhesion.
The inventors of the present invention estimate that the
resistance to degradation by zinc is realized by the following
reasons.
[0042]
Presumably, the main reason for the degradation of the
chlorinated rubber by zinc is hardening and embrittlement of
the polymer by zinc chloride (ZnCl2) which is formed by the
reaction between the chlorine and the zinc. More specifically,
the degradation of the chlorinated rubber by zinc is
postulated to involve the following elementary reactions (1)
to (4).
[0043]
(1) Dechlorination
The chlorinated polymer under the influence of heat is
postulated to undergo the dechlorination represented by the
following reaction scheme:

wherein RC1 is the chlorinated part of the chlorinated rubber,
RH is the polyolefin part of the chlorinated rubber, R-
represents polymer radical, and CI- represents chlorine
radical.
[0044]
(2) Formation of zinc chloride
Presumably, the hydrogen chloride formed by the
dechlorination formes zinc chloride (ZnCl2) by reacting with
zinc or zinc oxide by the reaction scheme:
2HC1 + Zn → ZnCl2 + H2
2HC1 + ZnO → ZnCl2 + H2O
[0045]
(3) Chain reaction of dechlorination and radical formation in
the presence of zinc chloride (ZnCl2)

The thus formed ZnCl2 is a Louis acid catalyst which
functions as a catalyst in the dechlorination of the
halogenated alkyl, and therefore, it should promote
dechlorination of the chlorinated rubber and formation of
polymer radical.
[Chemical formula 1]

wherein ROO- is polymer hydroperoxide radical, and ROOH is
polymer hydroperoxide.
[0046]
(4) Hardening
Mutual binding (hardening) or crosslinking of the thus
formed polymer radical results in the increase in the
crosslinking density, and the polymer becomes even more
brittle. The embrittled chlorinated rubber is subject to
crack formation and breakage by the externally applied stress,
thereby experiencing the degradation by zinc.
R- + R∙ → R-R
ROO- + R∙ → ROOR
[0047]
Based on such estimation of the mechanism of the
degradation by zinc of the chlorinated polymer, the inventors
of the present invention arrived at the following integral
countermeasure for such zinc degradation of the chlorinated
polymer.
(A) Trapping of chlorine (countermeasure for dechlorination
and ZnCl2 formation)
Formation of the ZnCl2 which is the catalyst for the
dechlorination can be suppressed if the chlorine that had left
the chlorinated rubber could be trapped without delay.
(B) Trapping of zinc (countermeasure for ZnCl2 formation)

Formation of the ZnCl2, and hence, dechlorination can be
suppressed if zinc in the chlorinated rubber could be
stabilized by chelation.
(C) Trapping of radical (countermeasure for hardening)
Mutual binding (hardening) of the polymer radical, and
hence, the embrittlement of the chlorinated rubber can be
suppressed if the polymer radical that had been formed could
be eliminated.
[0048]
Incorporation of the metal deactivator as described
above at a predetermined amount should prevent dechlorination
of the chlorinated rubber by chelation of the zinc that has
moved into the chlorinated rubber; suppress the reaction
between the hydrogen chloride generated by the dechlorination
of the chlorinated rubber and the zinc; and prevent the
dechlorination of the chlorinated rubber promoted by the zinc
chloride (ZnCl2) generated in such dechlorination acting as a
catalyst (see (B), above).
Incorporation of the acid acceptor at a predetermined
amount is believed to enable trapping of the hydrogen chloride
generated in the course of the dechlorination of the
chlorinated rubber to thereby suppress the promotion of the
decomposition of the chlorinated rubber and the generation of

the zinc chloride (ZnCl2) by the escaped hydrogen chloride
(see (A), above).
Furthermore, incorporation of the antioxidant at a
predetermined amount is believed to suppress generation of the
radicals generated in the initial stage of the chlorinated
rubber deterioration, and facilitate trapping of the polymer
radical as well as suppression of the mutual binding of the
polymer radical (hardening) (see (C), above).
[0049]
In the present invention, resistance to degradation by
zinc was evaluated as described below and in the Examples.
First, the vulcanized sheet comprising the rubber
composition of the present invention having a thickness of 2
mm was brought in contact with a zinc sheet, and after
compressing the laminate by 20%, the sheet was left in an oven
at 150°C for 72 hours.
The laminate was allowed to cool to room temperature,
and the vulcanized sheet was separated from the zinc sheet.
The vulcanized sheet was bent at an angle of 180°C by using a
clip, and the surface on the side that had been in contact
with the zinc sheet was checked for the generation of cracks
by using a microscope (at a magnification of 100),
The resistance to degradation by zinc was evaluated to
be acceptable when no cracks were found on the surface.

[0050]
If desired, the rubber composition of the present
invention may optionally contain additives such as a filler,
reinforcing agent, antiaging agent, vulcanizer, vulcanization
accelerator, vulcanization aid, plasticizer, pigment (dye),
tackifier, lubricant, dispersant, and processing aid at an
amount that does not adversely affect the object of the
present invention.
[0051]
The method used for producing the rubber composition of
the present invention is not particularly limited, and in an
exemplary method, the chlorinated rubber, the metal
deactivator, the acid acceptor, and the antioxidant are mixed
(kneaded) by an open roll, kneader, extruder, universal
agitator, batch kneader, or the like.
The temperature used for the mixing of the components is
not particularly limited since the temperature is determined
by the apparatus used for the mixing. When a batch kneader is
used for the mixing, the mixing is preferably conducted at a
temperature of 50 to 160°C, and more preferably at 50 to 120°C.
Also, the time used for the mixing is not particularly
limited since the temperature is determined by the apparatus
used for the mixing. In the case of a batch kneader, the
mixing is preferably accomplished in about 1 to 15 minutes.

[0052]
The hose of the present invention is a hose comprising
the rubber layer(s) formed by using the rubber composition of
the present invention and a reinforcement layer adjacent to
the rubber layer(s).
[0053]
A preferred embodiment of the hose of the present
invention is shown in FIG. 1. FIG. 1 is a perspective view in
which the layers of the hose are partially cut away.
As shown in FIG. 1, hose 1 comprises a rubber inner
layer 2 as an inner tube overlaid with a reinforcement layer 3
and a rubber outer layer 4 as an outer tube.
[0054]
Next, the rubber layers (the rubber inner layer and the
rubber outer layer) and the reinforcement layer constituting
the hose of the present invention are described in detail.
[0055]

The rubber layers are the layers adjacent to the
reinforcement layer, and the hose of the present invention has
the rubber inner layer and the rubber outer layer.
In the present invention, the rubber inner layer or the
rubber outer layer in contact with metal parts are formed by
using the rubber composition of the present invention in order

to improve resistance to degradation by zinc when such rubber
layer became in contact with a zinc-plated joint and other
metal parts. Even if the zinc plating is covered by another
plating layer of chromium or the like, the rubber composition
of the present invention may be used if the exposed zinc may
become in contact with the chlorinated rubber.
By forming the rubber layers using the rubber
composition of the present invention, a hose having an
improved resistance to degradation by zinc can be produced
even if the reinforcement layer was formed by using a fiber
material or a metal material such as a steel wire for the
reinforcement layer.
[0056]
In the present invention, the rubber inner layer may
have a thickness of 0.2 to 4.0 mm, and more preferably 0.5 to
2.0 mm. Similarly, the rubber outer layer may have a
thickness of 0.2 to 4.0 mm, and more preferably 0.5 to 2.0 mm.
[0057]

The reinforcement layer is the layer formed in the
exterior of the rubber inner layer as described above for the
purpose of maintaining the strength of the product.
In the present invention, the reinforcement layer may
comprise either a braid or a coil, and the material used for

the reinforcement layer is not particularly limited.
Exemplary preferable materials include polyester fibers,
polyamide fibers, alamid fibers, vinilon fibers, rayon fibers,
PBO (polyparaphenylene benzobisoxazole) fibers, polyallylate
fibers, and polyketone fibers. The reinforcement layer may
also comprise a metal reinforcement layer, and the metal
materials used for such reinforcement layer is also not
limited. Exemplary preferable metal materials include hard
steel wire (brass plated wires).
Among these, the preferred are polyester fibers and
polyamide fibers in view of the improved size stability, heat
resistance, and fatigue resistance.
[0058]
The method used for producing the hose of the present
invention comprising the rubber layer and the reinforcement
layer is not particularly limited, and any method known in the
art can be used in producing such hose of the present
invention.
In an exemplary process, the rubber inner layer, the
reinforcement layer, and the rubber outer layer may be
disposed in this order on a mandrel, and these layers may be
adhered by press vulcanization, vapor vulcanization, oven
vulcanization (hot air vulcanization), or hot water

vulcanization conducted for 30 to 180 minutes under the
conditions of 140 to 190°C.
Examples
[0059]
Next, the rubber composition of the present invention is
described in detail by referring to the Examples which by no
means limit the scope of the present invention.
[0060]
(Examples 1 to 14 and Comparative Examples 1 to 14)
The components shown in Table 1 were blended at the
ratio (part by weight) shown in Table 1 to prepare the rubber
composition.
More specifically, the components shown in Table 1
except for the crosslinking agent 1 were kneaded in Banbury
mixer (3.4 liters) for 4 minutes, and the content was removed
from the mixer when the temperature reached 140°C. The master
batch was thereby obtained.
Next, the crosslinking agent 1 was kneaded with the thus
obtained master batch by open rolls to prepare the rubber
composition.
The thus obtained rubber compositions were evaluated for
their tensile properties after vulcanization, resistance to
thermal aging, oil resistance, adhesion, and resistance to

degradation by zinc by the procedure as described below. The
results are shown in Table 1.
[0061]
(1) Tensile properties
The resulting rubber composition was vulcanized for 60
minutes by using a press molding machine at 157°C under the
surface pressure of 3.0 MPa to produce a vulcanized sheet
having a thickness of 2 mm. JIS No. 3 dumbbell test pieces
were blanked from this sheet, and tensile test was conducted
in accordance with JIS K6251-2004 at a tensile speed of 500
mm/minute to measure tensile strength (TB)[MPa], elongation at
break (EB)[%], and 50% modulus {M50) [MPa] at room temperature.
[0062]
(2) Resistance to thermal aging
The same vulcanized sheet having a thickness of 2 mm as
one used in measuring the tensile properties was left in an
oven at 150°C for 72 hours, and the sheet was measured for the
elongation at break (EB) [%] in accordance with JIS K6251-2004.
[0063]
(3) Oil resistance
The same vulcanized sheet having a thickness of 2 mm as
one used in evaluating the tensile properties was immersed in
a test oil (IRM 903, manufactured by Japan Sun Oil

Corporation., Ltd.) at 150°C for 72 hours, and elongation "at
break (EB) [%] after the immersion was measured by JIS K6258-
2003.
[0064]
(4) Adhesion
A test piece in the shape of a hose comprising a rubber
outer layer comprising the thus obtained rubber composition
and a reinforcement layer comprising the nylon 66 fibers
(comprising 3 twisted 1000 dtex strands) which had been dipped
in RFL solution was prepared by the procedure as described
below.
The nylon 66 fibers were braided on a mandrel having an
outer diameter of 34 mm to form the reinforcement layer.
Next, an unvulcanized sheet having a thickness of 2.5 mm
was formed by using the products of Examples 1 to 14 and
Comparative Examples 1 to 14, and this sheet was adhered on
the reinforcement layer. This test piece was then vulcanized
to prepare the vulcanized test piece.
The rubber outer layer was peeled off the hose-shaped
test piece at a peeling speed of 50 mm/min to measure the
adhesion strength (unit: N per width of 25 mm).
[0065]
(5) Resistance to degradation by zinc

The same vulcanized sheet having a thickness of 2 mm as
one used in measuring the tensile properties was brought in
contact with a zinc sheet, and after compressing the laminate
by 20%, the sheet was left in an oven at 150°C for 72 hours.
The laminate was allowed to cool to room temperature,
and the vulcanized sheet was separated from the zinc sheet.
The vulcanized sheet was bent at an angle of 180°C by using a
clip, and the surface on the side that had been in contact
with the zinc sheet was checked for the generation of cracks
by using a microscope (at a magnification of 100). When
cracks were found, their average length was measured.
[0066]

[Table 1]

[0067]
[Table 2]

[0068] [Table 3]

[0069}
The components indicated in Table 1 are as described
below.

- Chlorinated rubber 1: chlorinated polyethylene
(product name: Tyrin CM0136, chlorine content: 36%,
manufactured by Dupont Dow Elastmer)
- Chlorinated rubber 2: chlorosulfonated polyethylene
(product name: Hypalon 40S, chlorine content: 35%,
manufactured by Dupont)
- EPDM: ethylene-propylene-diene terpolymer (product
name: MITSUI EPT 4070, ethylene content: 56%, ethylidene
norbornene content: 8%, manufactured by Mitsui Petrochemical
Industries)
- NBR: nitrile rubber (product name: Nipol 1041, nitrile
content: 40.5%, Mooney viscosity ML (1+4 at 100°C): 82.5,
manufactured by ZEON Corporation)
- AEM: methyl acrylate-ethylene copolymer (product name:
VAMAC DP, Mooney viscosity ML (1+4 at 100°C): 22, manufactured
by Mitsui Du-Pont Polychemical)
- Magnesium oxide: kyowamag 150 (specific surface area
150 m2/g), manufactured by Kyowa Chemical Industry Co.,Ltd.
[0070]
- Metal deactivator 1: bisbenzylidenehydrazide oxalic
acid (product name: Inhibitor OABH, manufactured by Eastman)
- Metal deactivator 2: N,N+-bis[3-[3,5-di-t-butyl-4-
hydroxyphenyl]propionyl]hydrazine (product name: Irganox MD
1024, manufactured by Ciba-Geigy)

- Metal deactivator 3: 2,2'-oxamidebis[ethyl 3-(3,5-t-
butyl-4-hydroxyphenyl)propionate] (product name: Naugard XL-1,
manufactured by Shiraishi Calcium)
- Metal deactivator 4: disalicyloylhydrazide
decamethylene dicarboxylic acid (product name: Adeka Stab CDA-
6, manufactured by ADEKA)
- Acid acceptor 1: Ca-Mg-Zn based complex stabilizer
(product name: Adeka Stab RUP 110, manufactured by ADEKA)
- Acid acceptor 2: hydrotalcite (product name: DHT-4A,
manufactured by Kyowa Chemical Industry Co.,Ltd)
- Acid acceptor 3: sodium stearate (product name: SS-40N,
manufactured by Kao)
- Antioxidant 1: tetrakis [methylene-3(3',5'di-t-butyl-4-
hydroxyphenyl)propionate] methane (product name: Irganox 1010,
manufactured by Ciba-Geigy)
- Antioxidant 2: tris(nonylphenyl)phosphite (product
name: Adeka Stab 1178, manufactured by ADEKA)
- Antioxidant 3: dilauryl 3,3'-thiodipropionate (product
name: Antiox L, manufactured by NOF Corporation)
[0071]
- Carbon black 1: SRF grade carbon black, manufactured
by Asahi Carbon

- Processing aid: hydrophilic higher fatty acid ester
(product name: Struktol WB212, manufactured by Schill &
Seilacher GMBH & CO.)
- Crosslinking aid: pentaerythritol (product name:
Neulizer P, manufactured by The Nippon Synthetic Chemical
Industry Co., Ltd.)
- Plasticizer: isononyl trimellitate (product name: C-9N,
manufactured by ADEKA)
- Co-crosslinking agent: triallyl isocyanurate (product
name: TAIC, manufactured by Nippon Kasei)
- Crosslinking agent 1: dicumyl peroxide (product name:
Percumyl D-40, manufactured by NOF corporation)
[0072]
(Example 15 to 26 and Comparative Example 15 to 29)
The components shown in Table 2 were blended at the
ratio (part by weight) shown in Table 2 to prepare the rubber
composition.
More specifically, the components shown in Table 2
except for the crosslinking agent 2 were kneaded in Banbury
mixer (3.4 liters) for 4 minutes, and the content was removed
from the mixer when the temperature reached 140°C. The master
batch was thereby obtained.

Next, the crosslinking agent 2 was kneaded with the thus
obtained master batch by open rolls to prepare the rubber
composition.
The thus obtained rubber compositions were evaluated for
their tensile properties after vulcanization, resistance to
thermal aging, oil resistance, adhesion, and resistance to
degradation by zinc by the procedure as described above. The
results are shown in Table 2.

[0074][Table 5]

[0075]
The components shown in Table 2 which are different from
those shown in Table 1 are as described below.
- Carbon black 2: FEF grade carbon black, manufactured
by Nippon Steel Chemical Carbon Co., Ltd.
- Crosslinking agent 2: N,N'-m-phenylene dimaleimide
(product name: HVA-2, manufactured by Dupont)
[0076]
As evident from the results shown in Tables 1 and 2, the
rubber compositions prepared in Examples 1 to 26 containing
the metal deactivator, the acid acceptor, and the antioxidant
at the predetermined amount in relation to the chlorinated
rubber are rubber compositions which can be used in producing
a hose which has excellent resistance to degradation by zinc
simultaneously with the physical properties such as resistance
to thermal aging, oil resistance and adhesion, in contrast to
the rubber compositions prepared in Comparative Examples 1 to
29 not containing such components at the predetermined amount.
[0077]
The picture taken by a microscope in the evaluation of
the rubber compositions (the vulcanized rubber sheets)
prepared in Comparative Example 1 and Example 10 for their
resistance to degradation by zinc are shown in FIG. 2. The
picture taken by a microscope in the evaluation of the rubber

compositions (the vulcanized rubber sheets) prepared in
Comparative Example 15 and Example 24 are also shown in FIG. 3.
As evident from FIGS. 2 and 3, cracks were confirmed in the
vulcanized rubber sheets prepared in Comparative Examples 1
and 15 while no cracks were confirmed in the vulcanized rubber
sheets prepared in Examples 10 and 24.

CLAIMS
1. A chlorinated rubber composition comprising a
chlorinated rubber, a metal deactivator, an acid acceptor, and
an antioxidant, wherein
the metal deactivator is included at a content of at
least 0.3 parts by weight in relation to 100 parts by weight
of the chlorinated rubber,
the acid acceptor is included at a content of at least 1
parts by weight in relation to 100 parts by weight of the
chlorinated rubber, and
the antioxidant is included at a content of 0.1 to 10
parts by weight in relation to 100 parts by weight of the
chlorinated rubber.
2. A chlorinated rubber composition according to claim 1
wherein the metal deactivator is at least one member selected
from the group consisting of 1,2,3-benzotriazole, 3-(N-
salicyloyl)amino-1,2,4-triazole, decamethylenedicarboxylic
acid disalicyloylhydrazide-, N,N' -bis [3- (3,5-di-t-butyl-4-
hydroxyphenyl)propionyl]hydrazine, 2,2'-oxamidebis[ethyl 3-
(3,5-t-butyl-4-hydroxyphenyl)propionate], oxalic acid
bisbenzylidenehydrazide, isophthalic acid bis(2-phenoxy
propionylhydrazide), 2,4, 6-triamino-l,3,5-triazine,
ethylenediaminetetraacetic acid, alkali metal salt of

ethylenediaminetetraacetic acid, tris[2-t-butyl-4-thio(2'-
methyl-4'-hydroxy-5'-t-butyl) phenyl-5-methyl]-phenyl
phosphite, and 3,9-bis[2-(3,5-diamino-2,4,6-triazaphenyl)
ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane.
3. A chlorinated rubber composition according to claim 1 or
2 wherein the acid acceptor is at least one member selected
from the group consisting of Ca-Mg-Zn based complex stabilizer,
hydrotalcite, and fatty acid metallic soap.
4. A chlorinated rubber composition according to any one of
claims 1 to 3 wherein the antioxidant is at least one member
selected from the group consisting of phenol-based antioxidant,
phosphorus-based antioxidant, and sulfur-based antioxidant.
5. A hose comprising a rubber layer and a reinforcement
layer adjacent to the rubber layer formed by using the
chlorinated rubber composition of any one of claims 1 to 4.

A chlorinated rubber composition including a chlorinated rubber, a metal deactivator, an acid acceptor, and an antioxidant respectively at a particular amount is provided. The chlorinated rubber composition is capable of providing a
chlorinated rubber composition which can be used in producing a hose exhibiting excellent resistance to degradation by zinc together with the sufficient physical properties such as
resistance to thermal aging, oil resistance, and adhesion, as well as a hose produced by using such chlorinated rubber composition for the rubber layer.

CHLORINATED RUBBER COMPOSITION AND HOSE

Documents:

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PCT Conventions: