Rubber composition for hose and hose

Abstract

To provide a rubber composition for a hose and a hose that are excellent in oil resistance, product life and cold resistance.SOLUTION: A rubber composition for a hose includes: a rubber component including an acrylonitrile-butadiene copolymer rubber; carbon black; and a phosphoric ester, where an amount of acrylonitrile included in the acrylonitrile-butadiene copolymer rubber is 35-42 mass% based on the rubber component. A hose is formed using the rubber composition for a hose.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Marine hoses have been used as one type of hose, primarily for transporting gasoline and crude oil. Rubber compositions for marine hoses have been proposed, for example, as disclosed in Patent Document 1, with the aim of providing marine hoses and the like that can achieve both excellent oil resistance and long product life. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-138985 Summary of the Invention [Problem to be solved by the invention]

[0004] Under these circumstances, the present inventors, referring to Patent Document 1, prepared and evaluated rubber compositions containing extremely high nitrile NBR as acrylonitrile butadiene copolymer rubber (NBR) and diisononyl phthalate (DINP) as a plasticizer, and found that there are cases in which the above-mentioned rubber compositions have room for improvement in terms of oil resistance, product life, or cold resistance.

[0005] Therefore, an object of the present invention is to provide a rubber composition for a hose that is excellent in oil resistance, product life, and cold resistance. Another object of the present invention is to provide a hose. [Means for solving the problem]

[0006] As a result of intensive research to solve the above problems, the present inventors have found that the desired effects can be obtained by a rubber composition containing a rubber component containing acrylonitrile butadiene copolymer rubber (NBR), carbon black, and a phosphate ester, and the amount of acrylonitrile contained in the NBR is 35 to 42 mass % of the rubber component, thereby arriving at the present invention. The present invention is based on the above findings and solves the above problems by specifically providing the following configurations.

[0007] [1] A rubber composition for a hose, comprising a rubber component containing an acrylonitrile-butadiene copolymer rubber, carbon black, and a phosphate ester, wherein the amount of acrylonitrile contained in the acrylonitrile-butadiene copolymer rubber is 35 to 42 mass % of the rubber component. [2] The rubber composition for a hose according to [1], wherein the phosphate ester includes a triphosphate ester. [3] The rubber composition for a hose according to [1] or [2], wherein the phosphate ester contains tricresyl phosphate. [4] The rubber composition for a hose according to any one of [1] to [3], wherein the content of the phosphate ester is 10 to 30 parts by mass per 100 parts by mass of the rubber component. [5] The rubber composition for a hose according to any one of [1] to [4], wherein the carbon black comprises FT carbon black and / or SRF carbon black. [6] The rubber composition for a hose according to any one of [1] to [5], wherein the content of the carbon black is 60 to 100 parts by mass per 100 parts by mass of the rubber component. [7] The rubber composition for a hose according to any one of [1] to [6], further comprising a fatty acid metal salt. [8] The rubber composition for a hose according to any one of [1] to [7], further containing silica.

[0008] [9] A hose formed using the rubber composition for a hose according to any one of [1] to [8].

[10] The hose according to [9], which is a marine hose. [Effects of the Invention]

[0009] The rubber composition for a hose of the present invention has excellent oil resistance, product life, and cold resistance. Furthermore, the hose of the present invention has excellent oil resistance, product life, and cold resistance. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to". In this specification, unless otherwise specified, each component may be used alone or in combination of two or more substances. When a component contains two or more substances, the content of the component means the total content of the two or more substances. In this specification, the better the effect of the present invention, the better at least one of oil resistance, product life, and cold resistance.

[0011] [Rubber composition for hoses] The rubber composition for hoses of the present invention (rubber composition of the present invention) contains a rubber component containing an acrylonitrile-butadiene copolymer rubber, carbon black, and a phosphate ester, and the amount of acrylonitrile contained in the acrylonitrile-butadiene copolymer rubber is 35 to 42 mass % of the rubber component. Each component contained in the rubber composition of the present invention will be described in detail below.

[0012] [Rubber component] In the present invention, the rubber component contains an acrylonitrile butadiene copolymer rubber.

[0013] [Acrylonitrile-butadiene copolymer rubber] Acrylonitrile-butadiene copolymer rubber (NBR) is a copolymer of acrylonitrile and butadiene, or a hydrogenated product thereof.

[0014] <Amount of acrylonitrile> The amount of acrylonitrile in NBR (the amount of bound acrylonitrile; hereinafter sometimes referred to as "AN amount") is preferably 30% by mass or more, more preferably 35% by mass or more, and still more preferably 38% by mass or more in NBR from the viewpoint that the effects of the present invention (particularly oil resistance) are more excellent. Also, the AN amount of NBR is preferably 50% by mass or less, more preferably 42% by mass or less in NBR from the viewpoint that the effects of the present invention are more excellent. In the present invention, the amount of acrylonitrile in NBR can be measured by the Kjeldahl method in accordance with JIS K6451-2:2016.

[0015] [Other rubbers] The above rubber component may further contain rubbers other than NBR (other rubbers). Examples of other rubbers include conjugated diene rubbers such as natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), 1,2-butadiene rubber, styrene-butadiene rubber (SBR), chloroprene rubber (CR), and butyl rubber (IIR); and non-conjugated diene rubbers such as ethylene-propylene-diene rubber (EPDM).

[0016] <Content of NBR> The content of NBR (when two or more kinds of NBR are used in combination, the total amount of the above NBR) is preferably 80 to 100% by mass, more preferably 100% by mass in the total amount of the rubber component from the viewpoint that the effects of the present invention are more excellent.

[0017] [Amount of acrylonitrile in rubber component] In the present invention, the acrylonitrile amount (AN amount) of the acrylonitrile butadiene copolymer rubber (NBR) is 35 to 42 mass % in the rubber component. In the present invention, the AN amount of NBR in the rubber component is within the above numerical range, thereby providing excellent oil resistance, product life, and cold resistance. In the present invention, the AN amount of the NBR may be within the above-mentioned range in the rubber component, and there are no particular limitations on the NBR used and other rubbers that can be used as needed. The AN content of the NBR is preferably 38 to 41% by mass in the rubber component, from the viewpoint of achieving a better effect of the present invention.

[0018] NBR may be used alone or in combination of two or more. When two or more NBRs are used in combination, for example, NBRs having different AN amounts may be combined.

[0019] [Type of rubber component and AN amount] When the rubber component is only NBR When the rubber component is only NBR, the rubber component is entirely NBR, so the AN amount of the NBR may be 35 to 42% by mass. In the above case, NBR having an AN content of 35 to 42% by mass may be used alone, or two or more types of NBR having different AN contents may be used so long as the average AN content of these NBRs is 35 to 42% by mass.

[0020] When the rubber component further contains other rubbers When the rubber component further contains other rubber, the AN content of the NBR may be 35 to 42 mass % of the total amount of the rubber component.

[0021] [Carbon black] The rubber composition of the present invention contains carbon black. The carbon black is not particularly limited, and for example, conventionally known carbon black can be used.

[0022] <Nitrogen adsorption specific surface area of ​​carbon black> The nitrogen adsorption specific surface area (N2SA) of the carbon black is preferably 20 to 40 m from the viewpoint of achieving the effects of the present invention (especially oil resistance). 2 / g, and 20 to 30m 2 / g is more preferred. In the present invention, the nitrogen adsorption specific surface area of ​​carbon black can be measured in accordance with JIS K6217-2:2017 "Carbon black for rubber - Basic properties - Part 2: Determination of specific surface area - Nitrogen adsorption method - Single point method."

[0023] <Dibutyl phthalate oil absorption of carbon black> From the viewpoint of achieving better effects of the present invention (particularly oil resistance), the dibutyl phthalate oil absorption (DBP oil absorption) of the carbon black is preferably 20 to 80 ml / 100 g, and more preferably 20 to 50 ml / 100 g. In the present invention, the dibutyl phthalate oil absorption of carbon black can be measured in accordance with JIS K6217-4:2017 "Carbon black for rubber - Fundamental properties - Part 4: Determination of oil absorption (including compressed samples)."

[0024] From the viewpoint of achieving better effects of the present invention, the carbon black preferably contains soft carbon such as FT (Fine Thermal) carbon black, GPF (General Purpose Furnace) carbon black, or SRF (Semi-Reinforcing Furnace) carbon black, more preferably FT carbon black and / or SRF carbon black, and even more preferably FT carbon black.

[0025] [Carbon black content] From the viewpoint of achieving better effects of the present invention and excellent adhesion, the content of carbon black is preferably 60 to 100 parts by mass, more preferably 70 to 95 parts by mass, and even more preferably 75 to 85 parts by mass, per 100 parts by mass of the rubber component.

[0026] [Phosphate ester] The rubber composition of the present invention contains a phosphoric acid ester. A phosphate ester is a compound in which at least one OH group of phosphoric acid is esterified. In the present invention, the phosphate ester can function as a plasticizer that can plasticize or soften the rubber composition. The present invention provides excellent oil resistance, product life, and cold resistance by containing a phosphate ester. Furthermore, the present invention provides excellent oil resistance, product life, and cold resistance by containing a rubber component that includes acrylonitrile butadiene copolymer rubber (NBR) in which the acrylonitrile content of the NBR is 35 to 42 mass % in the rubber component, and a phosphoric acid ester.

[0027] Triphosphate ester From the viewpoint of achieving better effects of the present invention, the phosphate ester preferably contains triphosphate ester, and more preferably contains tricresyl phosphate. Triphosphate esters are compounds in which all of the hydrogen atoms of the OH groups of phosphoric acid are substituted with hydrocarbon groups.

[0028] The hydrocarbon group contained in the phosphate ester (the hydrocarbon group that substitutes the hydrogen atom of the OH group contained in the phosphoric acid and bonds to the oxygen atom) is not particularly limited. Examples include aliphatic hydrocarbon groups, aromatic hydrocarbon groups, and combinations thereof. From the viewpoint of achieving superior effects of the present invention, the hydrocarbon group preferably has an aromatic hydrocarbon group, and more preferably the aromatic hydrocarbon group is bonded to the oxygen atom of the OH group of the phosphoric acid to form an ester. The aromatic hydrocarbon group may also be bonded to an alkyl group. Examples of aromatic hydrocarbon groups include a phenyl group and a tolyl group (a group in which one hydrogen atom has been removed from the benzene ring of toluene).

[0029] Examples of tricresyl phosphate include compounds represented by the following formula: [ka]

[0030] <Phosphate ester content> The content of the phosphate ester is preferably 10 to 30 parts by mass, and more preferably 18 to 23 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint of achieving better effects of the present invention.

[0031] [Fatty acid metal salts] From the viewpoint of achieving superior effects of the present invention, the rubber composition of the present invention preferably further contains a fatty acid metal salt. The fatty acid metal salt is a salt of a fatty acid and a metal.

[0032] Examples of fatty acids that can form fatty acid metal salts include saturated fatty acids such as acetic acid, propionic acid, butanoic acid, pentanoic acid, isopentanoic acid, caproic acid (hexanoic acid), heptanoic acid, caprylic acid (octanoic acid), nonanoic acid, capric acid (decanoic acid), lauric acid (undecanoic acid), myristic acid (tetradecanoic acid), palmitic acid (hexadecanoic acid), stearic acid (octadecanoic acid), arachidic acid (eicosanoic acid), behenic acid (docosanoic acid), tetracosanoic acid, and hexacosanoic acid; unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, elaidic acid, and erucic acid; and hydroxy fatty acids such as ricinoleic acid and hydroxystearic acid. One type of fatty acid may be used alone, or two or more types may be used in combination.

[0033] Of these fatty acids, fatty acids having 6 or more carbon atoms are preferred from the viewpoint of achieving better effects of the present invention (particularly product life).

[0034] Examples of metals that can constitute fatty acid metal salts include alkali metals (lithium, potassium, sodium, etc.), alkaline earth metals (beryllium, magnesium, calcium, strontium, barium, etc.), transition metals (metals of groups 3 to 11), zinc, aluminum, germanium, tin, antimony, etc.

[0035] The metal is preferably zinc, from the viewpoints of providing a better effect of the present invention (particularly product life) and easily forming a complex with a fatty acid.

[0036] From the viewpoint of achieving better effects of the present invention (particularly oil resistance and product life), the fatty acid metal salt preferably contains a fatty acid zinc salt, and more preferably contains a saturated fatty acid zinc salt. Examples of zinc salts of fatty acids include at least one selected from the group consisting of zinc stearate, zinc oleate, zinc palmitate, zinc myristate, zinc laurate, and zinc linoleate. In the present invention, the fatty acid metal salt may be a mixture of the above-mentioned fatty acid metal salt with an aliphatic hydrocarbon and / or an inorganic filler (the same applies hereinafter).

[0037] The fatty acid metal salt preferably has a melting point of 85 to 105°C from the viewpoint of good processability. In the present invention, the melting point of the fatty acid metal salt can be measured by differential scanning calorimetry (DSC) in accordance with ASTM D3418 at a temperature increase rate of 10°C / min. When the fatty acid metal salt is used in the form of a mixture as described above, the melting point of the mixture can be the same as the melting point of the fatty acid metal salt described above.

[0038] Fatty acid metal salt content When the rubber composition of the present invention further contains a fatty acid metal salt, the content of the fatty acid metal salt is preferably 1.0 to 10 parts by mass per 100 parts by mass of the rubber component, from the viewpoint of achieving better effects of the present invention (particularly product life). When the fatty acid metal salt is used in the form of a mixture as described above, the content of the mixture per 100 parts by mass of the rubber component can be the same as the content of the fatty acid metal salt described above.

[0039] Furthermore, when the rubber composition of the present invention further contains a fatty acid metal salt, the mass ratio of the content of the phosphate ester to the content of the fatty acid metal salt (phosphate ester / fatty acid metal salt) is preferably 1.0 to 10.0, from the viewpoint of achieving better effects of the present invention. When the rubber composition of the present invention further contains a fatty acid metal salt and silica, the content of the fatty acid metal salt is preferably 5% by mass or more and less than 50% by mass, more preferably 5 to 45% by mass, of the silica content.

[0040] 〔silica〕 From the viewpoint of obtaining superior effects of the present invention, the rubber composition of the present invention preferably further contains silica. The silica is not particularly limited, and conventionally known silica can be used. The silica is preferably acidic silica, from the viewpoint of achieving a more excellent effect of the present invention. The pH of the acidic silica is not particularly limited as long as it is lower than 7. In the present invention, the pH of silica can be measured in accordance with JIS K5101-17-2:2004.

[0041] Silica content When the rubber composition of the present invention further contains silica, the content of silica is preferably 10 to 60 parts by mass, more preferably 15 to 50 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint of achieving better effects of the present invention.

[0042] [Additives] The rubber composition of the present invention may further contain additives as needed within the scope of the present invention, such as plasticizers other than phosphate esters, phenolic resins, antioxidants, antioxidants, antistatic agents, flame retardants, vulcanizing agents such as sulfur, vulcanization accelerators, zinc oxide, stearic acid, adhesion promoters, vulcanization retarders, and fillers other than silica and carbon black.

[0043] ·sulfur The rubber composition of the present invention preferably further contains sulfur, from the viewpoint of achieving superior effects of the present invention and excellent adhesion. The sulfur is not particularly limited. For example, conventionally known sulfur may be used. When the rubber composition of the present invention further contains sulfur, the content of sulfur is preferably 1 to 3 parts by mass, more preferably 1 to 2 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint of achieving better effects of the present invention and excellent adhesion.

[0044] Vulcanization accelerator From the viewpoint of achieving superior effects of the present invention and excellent adhesion, the rubber composition of the present invention preferably further contains a vulcanization accelerator, more preferably a sulfenamide vulcanization accelerator. The sulfenamide vulcanization accelerator is not particularly limited. For example, conventionally known sulfenamide vulcanization accelerators can be used. When the rubber composition of the present invention further contains a vulcanization accelerator, the content of the vulcanization accelerator is preferably 0.1 to 3 parts by mass, more preferably 0.5 to 2 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint of achieving better effects of the present invention and excellent adhesiveness.

[0045] The method for producing the rubber composition of the present invention is not particularly limited, and examples thereof include a method in which the above-mentioned components are mixed using a known method or apparatus (for example, a Banbury mixer, a kneader, a roll, etc.). The mixing temperature when producing the rubber composition of the present invention is preferably, for example, 50 to 120°C. The rubber composition of the present invention can be vulcanized under conventionally known vulcanization conditions.

[0046] The rubber composition of the present invention can be used to form a hose, such as a marine hose.

[0047] [hose] The hose of the present invention is a hose formed using the rubber composition for a hose of the present invention. The rubber composition used in the hose of the present invention is not particularly limited as long as it is the rubber composition of the present invention. The hose of the present invention is not particularly limited other than being formed using the above rubber composition. The hose of the present invention may be, for example, a marine hose.

[0048] There are no particular limitations on which component of a hose (e.g., a marine hose) the rubber composition of the present invention is used in. From the viewpoint of excellent oil resistance and the like, one preferred embodiment is to use the rubber composition of the present invention as the inner layer (e.g., the innermost layer) of a hose.

[0049] The hose of the present invention (for example, a marine hose; the same applies hereinafter) can have, for example, an innermost layer, a reinforcing layer, and an outermost layer in the above order. An intermediate rubber layer may further be provided between the innermost layer and the reinforcing layer, or between the reinforcing layer and the outermost layer. When a plurality of reinforcing layers are provided, an intermediate rubber layer may be further provided between the reinforcing layers. When the hose of the present invention has a plurality of reinforcing layers and can have an intermediate rubber layer between the reinforcing layers, the hose may have a configuration of, for example, innermost layer / [intermediate rubber layer / reinforcing layer]. n / intermediate rubber layer / outermost layer. In the above embodiment, the hose may have n layers of [intermediate rubber layer / reinforcing layer]. n may be, for example, 2 to 10. [Intermediate rubber layer / reinforcing layer] means, for example, a laminate of an intermediate rubber layer and a reinforcing layer, or an intermediate rubber layer previously applied to a reinforcing layer as a coating rubber.

[0050] [Innermost layer] One of the preferred embodiments of the hose of the present invention is one in which the innermost layer is formed using the rubber composition of the present invention. When the innermost layer is formed using the rubber composition of the present invention, the thickness of the innermost layer can be, for example, 1.5 to 8.0 mm.

[0051] [Reinforcing layer] The reinforcing layer is not particularly limited. Examples of materials for the reinforcing layer include metals and fiber materials (polyamide, polyester, etc.). Examples of the form of the reinforcing layer include those braided into a spiral structure or a braid structure, woven fabric (for example, canvas), and nonwoven fabric. The reinforcing layer may be surface-treated. Alternatively, the reinforcing layer may be one in which an intermediate rubber layer is previously applied to the reinforcing layer as a coating rubber. The thickness of a reinforcing layer (for example, one reinforcing layer) (or the thickness of a reinforcing layer to which a coating rubber has been applied in advance) can be, for example, 0.5 to 1.5 mm.

[0052] [Middle rubber layer] The intermediate rubber layer is not particularly limited, and examples of the rubber contained in the intermediate rubber layer include natural rubber and / or synthetic rubber. The thickness of the intermediate rubber layer can be, for example, 2.0 to 8.0 mm. When the intermediate rubber layer is formed by a reinforcing layer having a coating rubber applied to one or both sides in advance, the thickness of the intermediate rubber layer between the reinforcing layers (excluding the coating rubber layer) can be, for example, 0.5 mm or more.

[0053] [Outermost layer] The outermost layer is not particularly limited. The outermost layer may be, for example, a rubber layer. Examples of the rubber contained in the outermost layer include natural rubber and / or synthetic rubber. The outermost layer may be formed from the rubber composition of the present invention. The thickness of the outermost layer can be, for example, 2.0 to 10.0 mm.

[0054] The inner diameter of the hose of the present invention is not particularly limited and can be, for example, 10 to 30 inches. The length of the hose of the present invention is not particularly limited and can be, for example, 5 to 20 meters.

[0055] A method for producing a hose (e.g., a marine hose) formed from the rubber composition of the present invention involves, for example, first winding a sheet of the rubber composition of the present invention around a mandrel. The method for winding the sheet of the rubber composition of the present invention around the mandrel is not particularly limited, and examples include a method in which the sheets are wound while partially overlapping each other (e.g., spirally). Next, at least one layer selected from the group consisting of a resin layer, a reinforcing layer, an intermediate rubber layer, a buoyancy material layer, and an outermost layer (e.g., a cover rubber layer) can be laminated on the sheet of the rubber composition of the present invention. The various layers described above are not particularly limited. Examples include conventionally known layers. Furthermore, the materials, arrangement of the various layers in the hose, etc., are not particularly limited. The laminate obtained as described above can be subjected to vulcanization or the like to produce a hose (having an innermost layer) formed from the rubber composition of the present invention.

[0056] When the hose is a marine hose, since marine hoses are generally large, one preferred embodiment of the vulcanization or the like of the laminate is to initially heat the laminate at a temperature in the range of 100 to 110°C for 1 to 1.5 hours, and then heat it under conditions of 130 to 147°C to complete the vulcanization or the like. [Example]

[0057] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0058] <Production of Rubber Composition> A rubber composition was produced using the components in Table 1 below in the proportions (parts by mass) shown in the table. Specifically, the components shown in the table below, excluding sulfur and the vulcanization accelerator, were first mixed in a 1.5-liter internal mixer at 100°C for 5 minutes to obtain a masterbatch. Next, sulfur and the vulcanization accelerator were added to the obtained masterbatch in the amounts shown in the table below, and the mixture was mixed in an open roll at 50°C to produce a rubber composition.

[0059] <Evaluation> The rubber compositions produced as described above were subjected to the following evaluations, and the results are shown in Table 1. [Preparation of initial test specimen] Each rubber composition produced as described above was vulcanized for 195 minutes using a press molding machine at 148°C under a surface pressure of 3.0 MPa to prepare a vulcanized sheet having a thickness of 2 mm. In accordance with JIS K6251:2017, JIS No. 3 dumbbells were punched out from the vulcanized sheet to prepare initial test specimens.

[0060] [Oil resistance] The initial test specimen was immersed in test fuel oil C (2,2,4-trimethylpentane (isooctane) and toluene with a volume fraction of 50:50) specified in Appendix A of JIS K6258:2016 at room temperature for 48 hours. The volume of each test piece was measured before and after immersion, and the volume change rate was calculated using the following formula. Volume change rate (%) = [(volume after immersion - volume before immersion) / (volume before immersion)] × 100 ·Evaluation criteria for oil resistance In the present invention, a volume change rate of 26.0% or less was evaluated as having excellent oil resistance. The closer the volume change rate is to 0%, the more excellent the oil resistance is. On the other hand, when the volume change rate exceeded 26.0%, the oil resistance was evaluated as poor.

[0061] [Breaking characteristics (product life)] Using the initial test pieces, tensile tests were performed at room temperature at a tensile speed of 500 mm / min in accordance with JIS K6251:2017, and the fracture properties (breaking strength (TB) [MPa], elongation at break (EB) [%]) were measured. Product life evaluation criteria When TB was 13.0 MPa or more and EB was 450% or more, the product was evaluated as having a long lifespan. When the product life was evaluated as long, if TB was greater than 13.0 MPa and / or EB was greater than 450%, the product life was evaluated as longer. On the other hand, when TB was less than 13.0 MPa or EB was less than 450%, the product life was evaluated as short.

[0062] [Cold resistance (low temperature embrittlement)] Cold resistance was evaluated by measuring the low-temperature embrittlement temperature of the initial test specimens, which was measured in accordance with the "Low-temperature impact embrittlement test" of JIS K6261-2:2017. Cold resistance evaluation criteria When the low-temperature brittle temperature was less than -15.0°C, the cold resistance was evaluated as excellent. The lower the low-temperature brittle temperature is below -15.0°C, the better the cold resistance is evaluated to be. On the other hand, when the low-temperature brittle temperature was −15.0° C. or higher, the cold resistance was evaluated as poor.

[0063] [Table 1]

[0064] [Table 2]

[0065] The details of each component shown in Table 1 are as follows: NBR1: Nipol DN005M (AN content in NBR1: 45% by mass, Mooney viscosity: 50, manufactured by Zeon Corporation) NBR2: Nipol 1041 (AN content in NBR2: 40.5% by mass, Mooney viscosity: 78, manufactured by Zeon Corporation)

[0066] Carbon black: FT carbon (Asahi Thermal, nitrogen adsorption specific surface area 24m 2 / g, dibutyl phthalate oil absorption 28ml / 100g, Asahi Carbon Co., Ltd.)

[0067] Silica: Nipsil AQ (Tosoh Silica Corporation) acidic silica, pH 6.4

[0068] Comparative plasticizer: DINP: Diisononyl phthalate (manufactured by J-Plus) Phosphate ester TCP: Tricresyl phosphate (structure shown below, manufactured by Daihachi Chemical Industry Co., Ltd.) [ka]

[0069] Cardanol-derived phenolic resin: A compound derived from cardanol and represented by the following structure. Product name: CD-5L, manufactured by Tohoku Kako Co., Ltd. Liquid at 25°C. [ka] In the above structural formula, the position of each R is m relative to the OH group on each benzene ring. The above phenolic resin is a mixture of phenolic resins in which R is represented as follows and n is 1 to 3.

[0070] R=-C 15 H 31 (about 5%) -(CH2)7CH=CH(CH2)5CH3(approx. 35%) -(CH2)7CH=CHCH2CH=CH(CH2)2CH3(about 20%) -(CH2)7CH=CHCH2CH=CHCH2CH=CH2(about 40%) The percentage of each R is the mass % of the content of each R relative to the total amount of R contained in the phenolic resin.

[0071] Zinc oxide: Zinc oxide type 3 (Seongdong Chemical Industry Co., Ltd.) Stearic acid: Stearic acid YR (NOF CORPORATION) Antioxidant RD: Polymer of 2,2,4-trimethyl-1,2-dihydroquinoline (Nocrac 224, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)

[0072] Processing aid (fatty acid zinc): Mixed fatty acid zinc (trade name: Aktiplast ST, melting point: 85-100°C, manufactured by RheinChemie) contains saturated fatty acid zinc.

[0073] Sulfur: Oil-treated sulfur (Hosoi Chemical Industry Co., Ltd.) Vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazolylsulfenamide. Noccela CZ-G (Ouchi Shinko Chemical Industry Co., Ltd.) Vulcanization accelerator TOT-N: Tetrakis(2-ethylhexyl)thiuram disulfide. Noccela TOT-N (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)

[0074] From the results shown in Table 1, Comparative Examples 1, 2, and 5, in which the AN amount in the rubber component did not satisfy the predetermined range and no phosphate ester was contained, were at least poor in oil resistance and product life. Comparative Examples 2 and 5 also had poor cold resistance. Comparative Examples 3 and 4, in which the AN amount in the rubber component did not satisfy the predetermined range, were at least poor in oil resistance and cold resistance. Comparative Example 3 also had a poor product life. Comparative Examples 6 and 7, which did not contain a phosphate ester but contained DINP instead, had poor oil resistance.

[0075] In contrast, the rubber composition of the present invention is excellent in oil resistance, product life, and cold resistance. From the above results, it can be seen that the hose of the present invention (specifically, for example, a marine hose) has excellent oil resistance, product life, and cold resistance.

[0076] In Table 1, a comparison can be made between combination A of Comparative Examples 1 and 3 and combination B of Comparative Example 6 and Example 1 when replacing DINP with an equivalent amount of phosphate ester. That is, in combination B, in which the AN amount in the rubber component is within a predetermined range, when DINP in Comparative Example 6 was replaced with phosphate ester (Example 1), Example 1 improved to meet the standard values ​​in oil resistance, improved TB, suppressed a decrease in EB, and improved cold resistance compared to Comparative Example 6. On the other hand, in combination A, in which the AN amount in the rubber component is outside the predetermined range, when DINP in Comparative Example 1 was replaced with phosphate ester (Comparative Example 3), Comparative Example 3 continued to fail to meet the standard values ​​in oil resistance, and the EB and cold resistance were worse than those of Comparative Example 1, no longer meeting the standard values. When DINP was replaced with a phosphate ester containing an increased amount, a comparison of combination C in Comparative Examples 1 and 4 with combination D in Comparative Example 6 and Example 2 showed results similar to those of the comparison between combination A and combination B. The EB of Example 2 was improved compared to that of Comparative Example 6. From the above, it is believed that in the present invention, the combination of the amount of AN (derived from NBR) in the rubber component within a predetermined range and the use of a phosphate ester has an effect of improving oil resistance, product life, and cold resistance. The tendency of the effects of the present invention is believed to be different from when the amount of AN (derived from NBR) in the rubber component is outside the predetermined range and / or when a plasticizer other than a phosphate ester is used. In the present invention, the oil resistance and EB (product life) can be further improved by further increasing the content of phosphate ester in a rubber component in which the AN amount is within a predetermined range. Furthermore, when the rubber composition of the present invention further contains a fatty acid metal salt, the EB (product life) can be further improved.

Claims

1. a rubber component containing an acrylonitrile-butadiene copolymer rubber, carbon black, and a phosphate ester, wherein the amount of acrylonitrile contained in the acrylonitrile-butadiene copolymer rubber is 35 to 42% by mass of the rubber component; The rubber composition for a hose, wherein the phosphate ester includes a triphosphate ester.

2. The rubber composition for a hose according to claim 1 , wherein the phosphate ester comprises tricresyl phosphate.

3. 3. The rubber composition for a hose according to claim 1, wherein the content of the phosphate ester is 10 to 30 parts by mass based on 100 parts by mass of the rubber component.

4. The rubber composition for a hose according to any one of claims 1 to 3, wherein the carbon black comprises FT carbon black and / or SRF carbon black.

5. The rubber composition for a hose according to any one of claims 1 to 4, wherein the amount of the carbon black is 60 to 100 parts by mass based on 100 parts by mass of the rubber component.

6. The rubber composition for a hose according to any one of claims 1 to 5, further comprising a fatty acid metal salt.

7. The rubber composition for a hose according to any one of claims 1 to 6, further comprising silica.

8. A hose formed using the rubber composition for a hose according to any one of claims 1 to 7.

9. 9. The hose of claim 8, which is a marine hose.

Images