Rubber composition for hoses and hoses

Abstract

To provide: a rubber composition for a hose excellent in workability and excellent in flame retardancy, abrasion resistance and compression set of rubber obtained; and a hose.SOLUTION: Provided is a rubber composition for a hose, comprising: a rubber component including chloroprene rubber and butadiene rubber; sulfur; and an aromatic oil, where the content of the chloroprene rubber is 60 mass% or more and less than 75 mass% of the total mass of the rubber component, the content of the butadiene rubber is more than 25 mass% and 40 mass% or less of the total mass of the rubber component, the content of the sulfur is more than 0.2 pt.mass and less than 2.5 pts.mass relative to 100 pts.mass of the rubber component, the content of the aromatic oil is 10 pts.mass or more relative to 100 pts.mass of the rubber component, and the content of a silane coupling agent is 0-2 mass% relative to the total mass of the rubber component.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a rubber composition for hoses and a hose. [Background technology]

[0002] Hydraulic hoses used in construction machinery, machine tools, and other hydraulic systems (hydraulic piping hoses, hydraulic hoses) have seen increased use in coal mines and other mines in recent years, and therefore, flame retardancy is required for safety during operation. In this context, the flame retardancy required for hydraulic piping hoses is primarily defined in the MSHA standard (Mine Safety Authority of America) in the United States, for example.

[0003] As such a flame-retardant rubber composition for hoses, Patent Document 1 describes "a rubber composition for hoses comprising a rubber component, carbon black, and a plasticizer component, wherein 100 parts by mass of the rubber component contains 60 parts by mass or more of chloroprene rubber, and the carbon black is blended in proportion to 100 parts by mass of the rubber component, and the plasticizer component contains a flame-retardant plasticizer, wherein the flame-retardant plasticizer is blended in proportion to 100 parts by mass of the rubber component in proportion to 2 parts by mass or more" ([Claim 1]). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2016 / 199388 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] On the other hand, hydraulic hoses are prone to wear due to friction between the reels and other hoses, which causes the rubber outer layer to wear down. If this friction continues, the reinforcing wire layer may become exposed from the hydraulic hose, leading to premature failure of the hose. Thus, abrasion resistance is also required for hydraulic hoses. Under these circumstances, the inventors considered that incorporating chloroprene rubber (CR) and silica into the rubber composition would be effective in improving flame retardancy, and that incorporating a silane coupling agent into the rubber composition would be effective in improving abrasion resistance. Based on Patent Document 1, they prepared a rubber composition and evaluated it. However, it has been found that, depending on the rubber compounding or the silane coupling agent compounding, such rubber compositions may have a short scorch time, or the resulting rubber may have poor compression set or abrasion resistance. A short Mooney scorch time indicates poor processability (processing stability; the same applies hereinafter) of the rubber composition. As mentioned above, if the abrasion resistance is poor, the durability of the hose is likely to be reduced. If the compression set is poor, there is a high probability that leaks will occur at the point where the hose is connected.

[0006] Therefore, the present invention aims to provide a rubber composition for hoses that has excellent processability and the resulting rubber has excellent flame retardancy, abrasion resistance, and compression set. Furthermore, the present invention also aims to provide a hose that is excellent in processability, flame retardancy, abrasion resistance, and sealing properties. [Means for solving the problem]

[0007] As a result of diligent research to solve the above problems, the inventors of the present invention have found that the desired effect can be obtained by containing specific amounts of a rubber component including chloroprene rubber and butadiene rubber, sulfur, and an aromatic oil, and by having a silane coupling agent content of 0 to 2% by mass relative to the rubber component, leading to the present invention. The present invention is based on the above findings, and specifically solves the above problems with the following configuration.

[0008] [1] It contains rubber components including chloroprene rubber and butadiene rubber, sulfur, and aromatic oils. The chloroprene rubber content is 60% by mass or more and less than 75% by mass of the total mass of the rubber components. The content of the above-mentioned butadiene rubber is greater than 25% by mass and less than or equal to 40% by mass of the total mass of the above-mentioned rubber components. The sulfur content is greater than 0.2 parts by mass and less than 2.5 parts by mass per 100 parts by mass of the rubber component. The amount of the above-mentioned aromatic oil is 10 parts by mass or more per 100 parts by mass of the above-mentioned rubber component. A rubber composition for hoses, wherein the silane coupling agent content is 0 to 2% by mass relative to the total mass of the above rubber components. [2] The rubber composition for hoses according to [1], wherein the total content of the above-mentioned chloroprene rubber and the above-mentioned butadiene rubber exceeds 90% by mass of the total mass of the above-mentioned rubber components. [3] The rubber composition for hoses according to [1] or [2], wherein the rubber component consists solely of the chloroprene rubber and the butadiene rubber. [4] Furthermore, it contains carbon black, A rubber composition for hoses according to any one of [1] to [3], wherein the carbon black content is more than 50 parts by mass per 100 parts by mass of the rubber component. [5] A rubber composition for hoses according to any one of [1] to [4], wherein the sulfur content is 0.9 to 2.0 parts by mass per 100 parts by mass of the rubber component. [6] A rubber composition for hoses according to any one of [1] to [5], wherein the content of the flame retardant plasticizer is 0 parts by mass or less than 2 parts by mass per 100 parts by mass of the rubber component. [7] The chloroprene rubber content is 65% by mass or more and less than 75% by mass of the total mass of the rubber components. The content of the above-mentioned butadiene rubber is greater than 25% by mass and less than or equal to 35% by mass of the total mass of the above-mentioned rubber components. A rubber composition for hoses according to any one of [1] to [6], wherein the sulfur content is 0.9 to 1.3 parts by mass per 100 parts by mass of the rubber component. [8] Furthermore, a hose rubber composition according to any one of [1] to [7], containing silica.

[0009] [9] A hose having a rubber layer formed of a hose rubber composition according to any one of [1] to [8].

[10] The hose according to [9], wherein the rubber layer is the outermost layer. [Advantages of the Invention]

[0010] The hose rubber composition of the present invention is excellent in processability, and the resulting rubber is excellent in flame retardancy, abrasion resistance, and compression set. The hose of the present invention is excellent in processability, flame retardancy, abrasion resistance, and sealing performance. [Brief Description of the Drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing an example of the hose of the present invention with each layer cut away. [Figure 2] FIG. 2 is a perspective view showing another example of the hose of the present invention with each layer cut away. [Embodiments for Carrying Out the Invention] [[ID=X37]]

[0012] The present invention will be described in detail below. In this specification, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. In this specification, unless otherwise specified, each component can be used alone or in combination of two or more of the substances corresponding to the component. 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, with respect to the rubber composition for hoses, if at least one of the following is superior: processability, flame retardancy, abrasion resistance, and compression set, then the effect of the present invention may be considered superior. Furthermore, with respect to the hose, if at least one of the following is superior: processability, flame retardancy, abrasion resistance, and sealing properties, then the effect of the present invention may be considered superior.

[0013] [Rubber composition for hoses] The rubber composition for hoses of the present invention (the rubber composition of the present invention) It contains rubber components including chloroprene rubber and butadiene rubber, sulfur, and aromatic oils. The chloroprene rubber content is 60% by mass or more and less than 75% by mass of the total mass of the rubber components. The content of the above-mentioned butadiene rubber is greater than 25% by mass and less than or equal to 40% by mass of the total mass of the above-mentioned rubber components. The sulfur content is greater than 0.2 parts by mass and less than 2.5 parts by mass per 100 parts by mass of the rubber component. The amount of the above-mentioned aromatic oil is 10 parts by mass or more per 100 parts by mass of the above-mentioned rubber component. This is a rubber composition for hoses, wherein the silane coupling agent content is 0 to 2% by mass relative to the total mass of the above rubber components. The following describes in detail each component contained in the rubber composition of the present invention.

[0014] [Rubber components] In the present invention, the rubber component includes chloroprene rubber and butadiene rubber.

[0015] [Chloroprene rubber] In the present invention, the chloroprene rubber (CR) contained in the rubber component is not particularly limited. Examples of CRs include homopolymers of chloroprene, copolymers of chloroprene and monomers copolymerizable therewith. CR may be modified in ways such as sulfur modification, mercaptomodification, or chitosantogene modification.

[0016] [Butadiene rubber] In the present invention, the butadiene rubber (BR) contained in the rubber component is not particularly limited, and examples include conventionally known types. The weight-average molecular weight of butadiene rubber is not particularly limited, but is preferably 50,000 to 1,000,000, and more preferably 200,000 to 800,000.

[0017] From the viewpoint of achieving superior effects of the present invention, butadiene rubber having a high-cis structure is preferred. Specifically, butadiene rubber with a cis-1,4 bond content of 90% or more is more preferred, and butadiene rubber with a cis-1,4 bond content of 95% or more is even more preferred. High-cis butadiene rubber can be polymerized using conventional methods, such as those employing Ziegler catalysts or neodymium catalysts.

[0018] [CR content] In the present invention, the chloroprene rubber content is 60% by mass or more and less than 75% by mass of the total mass of the rubber components (of the total mass). Because the CR content is within the above range, the rubber composition of the present invention exhibits excellent flame retardancy, abrasion resistance, and compression set. From the viewpoint of achieving superior effects of the present invention (particularly flame retardancy), the CR content is preferably 65% ​​by mass or more and less than 75% by mass of the total mass of the rubber components.

[0019] [BR content] In the present invention, the butadiene rubber content is greater than 25% by mass and 40% by mass or less of the total mass of the rubber components. Because the BR content is within the above range, the rubber composition of the present invention exhibits excellent abrasion resistance and compression set. From the viewpoint of achieving superior effects of the present invention, the BR content is preferably more than 25% by mass and 35% by mass or less of the total mass of the rubber components.

[0020] (Total content of CR and BR) From the viewpoint of achieving superior effects of the present invention, the total content of chloroprene rubber and butadiene rubber is preferably more than 90% by mass of the total mass of the rubber components, and more preferably 95% by mass or more.

[0021] From the viewpoint of achieving superior effects in the present invention, it is preferable that the rubber component consists only of chloroprene rubber and butadiene rubber (containing only chloroprene rubber and butadiene rubber).

[0022] (Any rubber band) The rubber component may also contain any other rubber, provided that it contains chloroprene rubber and butadiene rubber in the above-mentioned mass percentages. Other optional rubbers include, for example, conjugated diene rubbers such as natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), butyl rubber (IIR), and halogenated butyl rubber (Br-IIR, Cl-IIR).

[0023] If any other rubber is styrene-butadiene rubber (SBR), the SBR content is preferably 0% by mass or less than 10% by mass of the total mass of the rubber components, from the viewpoint of achieving superior effects of the present invention.

[0024] [sulfur] The rubber composition of the present invention contains sulfur. The sulfur used is not particularly limited as long as it is in its elemental form. Examples include those that are already known.

[0025] [Sulfur content] In the present invention, the sulfur content is greater than 0.2 parts by mass and less than 2.5 parts by mass per 100 parts by mass of the above rubber component. Because the sulfur content is within this range, the rubber composition of the present invention exhibits excellent processability, wear resistance, and compression set. From the viewpoint of achieving superior effects of the present invention, the sulfur content is preferably 0.9 to 2.0 parts by mass, and more preferably 0.9 to 1.5 parts by mass, per 100 parts by mass of the rubber component.

[0026] (Content of CR, BR, and sulfur) In terms of the combination of the contents of CR, BR, and sulfur being more excellent in the effects of the present invention (particularly, having more excellent scorch time and flame retardancy, and excellent balance among scorch time, flame retardancy, compression set, and abrasion resistance), the content of chloroprene rubber is preferably 65% by mass or more and less than 75% by mass of the total mass of the rubber components, the content of butadiene rubber is preferably more than 25% by mass and 35% by mass or less of the total mass of the rubber components, and the content of sulfur is preferably 0.9 to 1.3 parts by mass per 100 parts by mass of the rubber components.

[0027] [Aromatic oil] The rubber composition of the present invention contains an aromatic oil. In the present invention, the aromatic oil refers to an oil in which the content rate (C A ) of aromatic hydrocarbons contained in a certain oil is 20% by mass or more in that oil.

[0028] (C A ) The content rate (C A ) of aromatic hydrocarbons in the aromatic oil is preferably 25 to 70% by mass from the viewpoint of the effects of the present invention being more excellent. (C P ) The content rate (C P ) of paraffinic hydrocarbons in the aromatic oil is preferably 20 to 70% by mass from the viewpoint of the effects of the present invention being more excellent. (C N ) The content rate (C N ) of naphthenic hydrocarbons in the aromatic oil is preferably 10 to 50% by mass from the viewpoint of the effects of the present invention being more excellent. C A , C P , C N of the oil can be measured according to the ring analysis method (n-d-M method) (ASTM D3238).

[0029] [Aromatic oil] In the present invention, the content of aromatic oil is 10 parts by mass or more per 100 parts by mass of the above-mentioned rubber component. Due to this aromatic oil content, the rubber composition of the present invention exhibits excellent processability. From the viewpoint of achieving superior effects of the present invention, the amount of aromatic oil is preferably 10 to 25 parts by mass, more preferably 11 to 18 parts by mass, and even more preferably 11 to 14 parts by mass, per 100 parts by mass of the rubber component.

[0030] [Silane coupling agent] In the present invention, the content of the silane coupling agent is 0 to 2% by mass relative to the total mass of the rubber components. By having the silane coupling agent content within this range, the rubber composition of the present invention exhibits excellent compression set. From the viewpoint of achieving superior effects of the present invention, the content of the silane coupling agent is preferably 0 to 1% by mass relative to the total mass of the rubber components.

[0031] The silane coupling agent is not particularly limited as long as it is a compound that can be used as a silane coupling agent in a rubber composition. A silane coupling agent typically refers to a compound having a hydrolyzable silyl group and a functional group (which does not include a hydrolyzable silyl group). Examples of hydrolyzable silyl groups include alkoxysilyl groups. Examples of the functional groups include hydroxyl groups, amino groups, epoxy groups, and thiol groups. The hydrolyzable silyl group and the functional group can be bonded via a linking group, and the linking group is not particularly limited.

[0032] (Carbon Black) The rubber composition of the present invention preferably further contains carbon black, as this improves the reinforcing properties of the resulting rubber or hose. There are no particular restrictions on the type of carbon black. Examples of carbon black include SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS, FEF, GPF, and SRF. Carbon black can be used alone or in combination of two or more types.

[0033] (Carbon black content) If the rubber composition of the present invention further contains carbon black, the carbon black content is preferably more than 50 parts by mass, more preferably 60 to 90 parts by mass, and even more preferably 65 to 80 parts by mass, per 100 parts by mass of the above rubber component, from the viewpoint of achieving superior effects of the present invention and improving the reinforcing properties of the resulting rubber (or hose).

[0034] (silica) From the viewpoint of achieving superior effects of the present invention (particularly flame retardancy), the rubber composition of the present invention preferably further contains silica. The type of silica is not particularly limited. Examples of silica include natural silica, fused silica, amorphous silica, hollow silica, and fumed silica. If the rubber composition of the present invention further contains silica, the silica content is preferably 5 to 25 parts by mass, and more preferably 10 to 20 parts by mass, per 100 parts by mass of the above rubber component, from the viewpoint of achieving superior effects of the present invention.

[0035] (Flame retardant plasticizer) In the present invention, the content of the flame retardant plasticizer is preferably 0 parts by mass or less than 2 parts by mass, and more preferably 0 to 1 part by mass, per 100 parts by mass of the rubber component.

[0036] The flame-retardant plasticizer is not particularly limited as long as it is a plasticizer that has flame retardant properties. Examples of flame-retardant plasticizers include chlorinated aliphatic compounds such as chlorinated paraffins; halogenated phosphate ester compounds such as trischloropropyl phosphate and condensates of trischloropropyl phosphate and dialkylene glycol; non-halogenated phosphate ester compounds such as triphenyl phosphate and tricresyl phosphate; and silicone compounds such as polydialkylsiloxanes. Furthermore, the flame retardant plasticizer does not contain the above-mentioned aromatic oils.

[0037] (Additives) The rubber composition of the present invention may further contain additives as needed. Examples of additives include aromatic oils, plasticizers other than flame retardant plasticizers, fillers other than silica and carbon black, softeners, anti-aging agents, antioxidants, antistatic agents, flame retardants (excluding flame retardant plasticizers), vulcanization accelerators, vulcanization accelerators (e.g., stearic acid, zinc oxide), vulcanization retarders, adhesion aids, waxes, and the like.

[0038] • Plasticizers other than aromatic oils and flame retardants Examples of plasticizers other than aromatic oils and flame retardants include ester compounds such as dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate (DOA), isodecyl succinate, diethylene glycol dibenzoate, pentaerythritol ester, butyl oleate, methyl acetylricinoleate, trimellitic acid ester, propylene glycol adipate polyester, and butylene glycol adipate polyester; naphthenic oils and paraffinic oils.

[0039] Flame retardant Examples of flame retardants include inorganic oxides (excluding silica) such as aluminum hydroxide and magnesium hydroxide. If the rubber composition of the present invention further contains the above-mentioned flame retardant, the amount of the flame retardant (excluding silica) is preferably 1 to 10 parts by mass per 100 parts by mass of the above-mentioned rubber component, from the viewpoint of achieving superior effects of the present invention (particularly flame retardancy).

[0040] (Method for manufacturing rubber composition) The method for producing the rubber composition of the present invention is not particularly limited. For example, one method may involve mixing the above-mentioned components using known methods and apparatus (e.g., Banbury mixer, kneader, roll, etc.). If the rubber composition of the present invention contains a vulcanizing agent or a vulcanization accelerator, for example, the rubber composition can be produced by mixing the above essential components and optional additives (excluding the vulcanizing agent and vulcanization accelerator) in a Banbury mixer or the like to prepare a mixture, and then adding the vulcanizing agent and vulcanization accelerator to the above mixture and mixing them further. The vulcanization of the rubber composition of the present invention is not particularly limited. For example, it can be vulcanized by conventionally known methods and conditions.

[0041] The rubber composition of the present invention can be used as a rubber composition for hoses. A hose having a rubber layer formed with the rubber composition of the present invention can be a flame-retardant hose.

[0042] [hose] The hose of the present invention is a hose having a rubber layer formed from the rubber composition for hoses of the present invention.

[0043] The hose of the present invention may be any hose having a rubber layer formed from the rubber composition for hoses of the present invention. The rubber composition used to form the rubber layer of the hose of the present invention is not particularly limited as long as it is the rubber composition for hoses of the present invention (the rubber composition of the present invention). The hose of the present invention has a rubber layer formed using the rubber composition of the present invention, and therefore exhibits good processability, flame retardancy, abrasion resistance, and sealing properties (compression set). The hose of the present invention can be used as a flame-retardant hose.

[0044] [Rubber layer] Typical rubber layers found in ordinary hoses include, for example, an outermost layer, an inner layer, and an intermediate rubber layer. The hose of the present invention, like ordinary hoses, can also have, for example, an outermost layer, an inner layer, and an intermediate rubber layer as its rubber layers. In the hose of the present invention, the rubber layer formed using the rubber composition of the present invention may be the outermost layer, the inner layer, or the intermediate rubber layer.

[0045] In the hose of the present invention, the rubber layer formed using the rubber composition of the present invention is preferably at least the outermost layer, from the viewpoint of achieving superior effects of the present invention. When the outermost layer of the hose of the present invention is a rubber layer formed using the rubber composition of the present invention, the rubber composition forming the inner layer is not particularly limited and may be the rubber composition of the present invention. The same applies to the intermediate rubber layer.

[0046] <Outermost layer> One preferred embodiment of the present invention is that the hose has an outermost layer, and the outermost layer is formed using the rubber composition of the present invention. The thickness of the outermost layer can be 0.2 to 4 mm.

[0047] <Inner layer> The rubber composition forming the inner layer is not particularly limited. For example, conventionally known compositions can be used. The inner layer may also be formed using the rubber composition of the present invention. The thickness of the inner layer can be, for example, 0.2 to 4 mm.

[0048] <Intermediate rubber layer> The rubber composition forming the intermediate rubber layer is not particularly limited. For example, conventionally known compositions can be used. The intermediate rubber layer may also be formed using the rubber composition of the present invention. The hose of the present invention may have one or more intermediate rubber layers. The thickness of the intermediate rubber layer can be, for example, 0.2 to 0.7 mm.

[0049] <Reinforcement layer> If there are multiple rubber layers, the hose of the present invention may have further reinforcing layers between the rubber layers. The reinforcing layers may be one or more. The material of the reinforcing layer is not particularly limited. Examples include metals and fibrous materials (polyamide, polyester, etc.). Examples of the form of the reinforcing layer include braids and spirals.

[0050] The hose of the present invention will be described below with reference to the attached drawings. However, the present invention is not limited to the attached drawings. Figure 1 is a perspective view showing an example of the hose of the present invention, with each layer cut out. In Figure 1, the hose 1 has an inner layer 2, a reinforcing layer 3 on top of it, and an outermost layer 4 as the outer layer.

[0051] Figure 2 is a perspective view showing another example of the hose of the present invention, with each layer cut out. In Figure 2, the hose 5 has an inner layer 10 as its innermost layer, an outermost layer 23, and between the inner layer 10 and the outermost layer 23, it alternately has intermediate rubber layers 11, 13, 15, 17, 19, 21 and reinforcing layers 12, 14, 16, 18, 20, 22.

[0052] (Hose manufacturing method) The hose of the present invention is not particularly limited by its manufacturing method. For example, one method of manufacturing the hose of the present invention involves laminating an inner layer, an intermediate rubber layer, a reinforcing layer, and an outermost layer on a mandrel in that order, and then covering the laminate with nylon cloth or the like, and then vulcanizing and bonding it by steam vulcanization, oven vulcanization (hot air vulcanization), or hot water vulcanization at a temperature of 140 to 190°C.

[0053] (Uses of hoses) The hose of the present invention can be used, for example, as a hydraulic hose, a refrigerant transport hose, a marine hose, and the like. [Examples]

[0054] The present invention will be specifically described below with reference to examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the examples shown below.

[0055] <Manufacturing of rubber compositions> Using a Banbury mixer, the components listed in Table 1 below, excluding four components (sulfur, zinc oxide, vulcanization accelerator TS, and vulcanization accelerator DPG), were mixed in the proportions (parts by mass) shown in the same table to prepare a masterbatch. Next, the four components mentioned above were added to the obtained masterbatch, and these were mixed in an open roll to produce each rubber composition.

[0056] <Rating> The following evaluations were performed using each rubber composition manufactured as described above. The results are shown in Table 1. Each evaluation result, except for flame retardancy, is expressed as an index with the result of Comparative Example 5 set to 100.

[0057] <Mooney's Scorch Test: Processability> For each rubber composition obtained, the scorch time (ML 5 up) was measured using a Mooney viscometer (L-type rotor) in accordance with the "Mooney scorch test" described in JIS K6300-1:2013 (Unvulcanized rubber - Physical properties - Part 1: Method for determining viscosity and scorch time using a Mooney viscometer), under the conditions of a preheating time of 1 minute and a test temperature of 125°C.

[0058] • Criteria for evaluating scorching time If the scorch time (index) was 40 or higher, the processability of the rubber composition was evaluated as excellent and indicated with a "○". If the scorch time (index) was 80 or higher, the processability of the rubber composition was even better. On the other hand, if the scorch time (index) was less than 40, the processability of the rubber composition was evaluated as poor and indicated as "×".

[0059] <Compression set: sealing properties> Each of the obtained rubber compositions was vulcanized using a press molding machine at 148°C and a surface pressure of 3.0 MPa for 45 minutes to create sheets. These sheets were then punched out to a diameter of 13.0 ± 0.5 mm and a thickness of 6 mm to produce disc-shaped test specimens. Using the above test specimens, the compression set (%) was measured in accordance with JIS K6262:2013 at a test temperature of 100°C, a test time of 72 hours, and a compressibility of 25%.

[0060] • Evaluation criteria for compression set In this invention, if the compression set (index) is less than 100, the sealing performance of the hose is evaluated as excellent and is indicated by "○". The lower the compression set (index) is below 100, the better the sealing performance of the hose, and if the compression set (index) is 77 or less, the sealing performance is even better. On the other hand, if the compression set (index) was 100 or higher, the hose's sealing performance was evaluated as poor and marked with "×".

[0061] <Abrasion resistance (pico abrasion test)> For each rubber composition obtained, test specimens were prepared by vulcanizing them for 45 minutes at 148°C and a surface pressure of 3.0 MPa using a press molding machine, in accordance with JIS K6264-2:2005 (pico abrasion test). The amount of abrasion (mL) was then measured using these test specimens at 23°C, with an applied force of 44 N and a rotation speed of 60 ± 2 rotations per minute.

[0062] • Evaluation criteria for wear testing In this invention, if the wear amount (index) is 110 or less, it is evaluated as having excellent wear resistance and is indicated by "○". The lower the wear amount (index) is than 110, the better the wear resistance. On the other hand, if the wear amount (index) exceeded 110, it was evaluated as having poor wear resistance and was marked with "×".

[0063] <Flame-retardant> Each of the obtained rubber compositions was press-vulcanized in a mold at 148°C and a surface pressure of 3.0 MPa for 45 minutes. Flame retardancy evaluation samples were obtained by cutting out pieces from the resulting vulcanized rubber sheets that were 150 mm long, 12.7 mm wide, and 2.5 mm thick. Based on the flame retardancy evaluation of the MSHA standard (US Mine Safety Standard) ASTP5007 (version: 2012-02-12), the flame extinction time and afterglow extinction time were measured using the flame retardancy evaluation samples obtained as described above. The flame retardancy was evaluated by applying the obtained flame extinction time and afterglow extinction time to the following criteria.

[0064] • Evaluation criteria for flame extinction time and afterglow extinction time If the flame extinction time was 30 seconds or less and the afterglow extinction time was 120 seconds or less, it was evaluated as having superior flame retardancy and was marked with "◎". If the flame extinction time was 60 seconds or less and the afterglow extinction time was 180 seconds or less, it was evaluated as having excellent flame retardancy and was marked with "〇". However, this excludes the above-mentioned ◎. If the flame extinction time exceeded 60 seconds or the afterglow extinction time exceeded 180 seconds, the flame retardancy was evaluated as poor and marked with "×".

[0065] [Table 1]

[0066] [Table 2]

[0067] [Table 3]

[0068] [Table 4]

[0069] The details of each component shown in Table 1 are as follows: (Rubber component) • BR: Butadiene rubber. Nipol BR1220 (manufactured by Nippon Zeon Co., Ltd.) • CR: Chloroprene rubber. Denka Chloroprene S-41 (manufactured by Denka Co., Ltd.) • SBR: Styrene-butadiene rubber. Nipol 1502 (manufactured by Zeon Corporation)

[0070] • CB (FEF): Carbon Black. Nitelon #10N (FEF grade carbon black, manufactured by Shin-Nippon Chemical Carbon Co., Ltd.) • Silica: NipSeal AQ (manufactured by Tosoh Silica Co., Ltd.) • Magnesium oxide: Kyowa Mag 150 (manufactured by Kyowa Chemical Industry Co., Ltd.)

[0071] • Stearic acid: Industrial grade stearic acid N (manufactured by Chiba Fatty Acid Co., Ltd.)

[0072] • Silane coupling agent: Si69 [Bis-(3-triethoxysilylpropyl)tetrasulfide, manufactured by Evonik Degussa]

[0073] • Aromatic oil: Aromatic oil. A / O MIX 2010 (manufactured by Sankyo Yuka Kogyo Co., Ltd.). The above product is an aromatic oil (containing aromatic hydrocarbons (C)) in the present invention. A This corresponds to an oil in which ) makes up 20% or more by mass of the oil.

[0074] • Zinc oxide: 3 types of zinc oxide (manufactured by Seido Chemical Industry Co., Ltd.) • Sulfur: Oil-treated sulfur (manufactured by Hosoi Chemical Industry Co., Ltd.) • Vulcanization accelerator TS: Sunceller TS-G (manufactured by Sanshin Chemical Industry Co., Ltd.) • Vulcanization accelerator DPG: Sunceller DG (manufactured by Sanshin Chemical Industry Co., Ltd.)

[0075] As shown in Table 1, Comparative Example 1, in which BR and CR did not meet the specified content levels, exhibited poor flame retardancy. Comparative Examples 2 and 7, which did not meet the specified range for the content of aromatic oils, exhibited poor processability. Comparative Examples 3 and 9, which contained more sulfur than the specified range, exhibited poor processability. Comparative Example 4, in which the BR content was 25% by mass of the rubber component and the CR content was 75% by mass of the rubber component, exhibited poor abrasion resistance. Comparative Example 5, which contained a silane coupling agent at an amount of 3% by mass of the total rubber component content, exhibited poor compression set (sealing performance as a hose). Comparative Example 6, in which BR did not meet the specified content, exhibited poor compression set (sealing performance as a hose) and abrasion resistance. Comparative Example 8, in which the amount of sulfur was below the specified range, exhibited poor abrasion resistance.

[0076] In contrast, the rubber composition of the present invention exhibits excellent processability, and the resulting rubber has superior flame retardancy, abrasion resistance, and compression set. Based on the above results, it can be said that the hose of the present invention has excellent processability, flame retardancy, abrasion resistance, and sealing properties. [Explanation of Symbols]

[0077] 1, 5: Hose 2, 10: Inner layer 3, 12, 14, 16, 18, 20, 22: Reinforcement layer 4, 23: Outermost layer 11, 13, 15, 17, 19, 21: Intermediate rubber layer

Claims

1. It contains rubber components including chloroprene rubber and butadiene rubber, sulfur, and aromatic oils. The chloroprene rubber content is 65% by mass or more and less than 75% by mass of the total mass of the rubber components. The content of the butadiene rubber is greater than 25% by mass and less than or equal to 35% by mass of the total mass of the rubber components. The sulfur content is greater than 0.2 parts by mass and less than 2.5 parts by mass per 100 parts by mass of the rubber component. The amount of the aromatic oil is 10 parts by mass or more per 100 parts by mass of the rubber component. A rubber composition for hoses, wherein the content of the silane coupling agent is 0 to 2% by mass relative to the total mass of the rubber components.

2. The rubber composition for hoses according to claim 1, wherein the total content of the chloroprene rubber and the butadiene rubber exceeds 90% by mass of the total mass of the rubber components.

3. The rubber composition for hoses according to claim 1 or 2, wherein the rubber component consists only of the chloroprene rubber and the butadiene rubber.

4. Furthermore, it contains carbon black, The rubber composition for hoses according to any one of claims 1 to 3, wherein the carbon black content is more than 50 parts by mass per 100 parts by mass of the rubber component.

5. The rubber composition for hoses according to any one of claims 1 to 4, wherein the sulfur content is 0.9 to 2.0 parts by mass per 100 parts by mass of the rubber component.

6. The rubber composition for hoses according to any one of claims 1 to 5, wherein the content of the flame retardant plasticizer is 0 parts by mass or less than 2 parts by mass per 100 parts by mass of the rubber component.

7. The rubber composition for hoses according to any one of claims 1 to 6, wherein the sulfur content is 0.9 to 1.3 parts by mass per 100 parts by mass of the rubber component.

8. Furthermore, the rubber composition for hoses according to any one of claims 1 to 7, further containing silica.

9. A hose having a rubber layer formed of the rubber composition for hoses described in any one of claims 1 to 8.

10. The hose according to claim 9, wherein the rubber layer is the outermost layer.

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