Rubber composition for hose and hose

Abstract

Provided is a hose which suppresses sticking between outer peripheral surfaces of the hose and has excellent compression set properties.　A rubber composition for a hose contains the following components (A)-(C), and the mass ratio ((A) / (B)) of component (A) to component (B) is 95 / 5-50 / 50.　(A) ethylene-(meth)acrylic acid ester binary copolymer, (B) ethylene-(meth)acrylic acid ester-carboxy group-containing monomer ternary copolymer, (C) organic peroxide crosslinking agent

Description

Rubber Composition for Hoses and Hoses

[0001] The present invention relates to a rubber composition for hoses. More specifically, the present invention relates to a rubber composition for hoses that is used as a material for oil hoses in transportation equipment such as automobiles, intake system hoses such as turbo air hoses, differential pressure sensor hoses such as for GPF, DPF, and EGR, exhaust system hoses such as for EGR, and to a hose using the composition.

[0002] Properties such as heat resistance and compression set resistance are required for oil hoses in transportation equipment such as automobiles, intake system hoses such as turbo air hoses, differential pressure sensor hoses such as for GPF, DPF, and EGR, and exhaust system hoses such as for EGR. Acrylic rubber, which is particularly excellent in heat resistance, is used as a material for forming these hoses (see Patent Documents 1 to 3). Specifically, for example, from the viewpoint of excellent strength and heat resistance, an ethylene-acrylate binary copolymer used in an organic peroxide crosslinking system is often used.

[0003] Japanese Patent No. 3587221, Japanese Patent No. 5252774, Japanese Unexamined Patent Publication No. 2012-207748

[0004] After being manufactured, the above-described hoses are stored in factories, warehouses, or transported to other locations. For convenience at that time, a plurality of the hoses are often brought into close contact and bundled with a string or the like. However, when hoses manufactured using the above ethylene-acrylate binary copolymer are bundled as described above, the outer peripheral surfaces of the hoses tend to stick firmly to each other. This imposes a great burden on workers when separating the stuck hoses into individual hoses, and furthermore, there is a risk that the outer peripheral surfaces of the hoses may be damaged during separation. Therefore, further improvement is required.

[0005] The present invention has been made in view of such circumstances, and provides a rubber composition for hoses that suppresses sticking between outer peripheral surfaces of hoses after manufacture and has excellent compression set properties, and various hoses obtained using the same.

[0006] In the process of diligently studying how to suppress the adhesion between the outer surfaces of the hoses, the inventors newly discovered that using a binary copolymer of ethylene-(meth)acrylic acid ester and a ternary copolymer of ethylene-(meth)acrylic acid ester and a carboxyl group-containing monomer tends to suppress the adhesion between the outer surfaces of the hoses. Based on this new finding, the inventors conducted further studies to simultaneously satisfy various properties required for various types of hoses. As a result, they found that by using a binary copolymer of ethylene-(meth)acrylic acid ester and a ternary copolymer of ethylene-(meth)acrylic acid ester and a specific blending ratio of the two, it is possible to reduce the tackiness of the outer surfaces of the hoses, suppress the adhesion between the outer surfaces of the hoses, and furthermore, achieve excellent compression set properties.

[0007] In other words, the gist of the present invention is as follows: [1] A rubber composition for hoses containing the following components (A) to (C), wherein the mass ratio of component (A) to component (B) ((A) / (B)) is 95 / 5 to 50 / 50. (A) Ethylene-(meth)acrylic acid ester binary copolymer (B) Ethylene-(meth)acrylic acid ester-carboxyl group-containing monomer terpolymer (C) Organic peroxide crosslinking agent [2] The rubber composition for hoses according to [1], wherein the content of component (C) is 0.8 to 2.5 parts by mass per 100 parts by mass of the total of components (A) and (B). [3] The rubber composition for hoses according to [1] or [2], further containing (D) a cocrosslinking agent. [4] The rubber composition for hoses according to any one of [1] to [3], further containing at least one of an organopolysiloxane and an alkylamine. [5] A hose rubber composition according to any one of [1] to [4], further comprising a modified organopolysiloxane having vinyl groups at its ends. [6] A hose comprising a layered structure in which a rubber layer made of the hose rubber composition according to any one of [1] to [5] and a rubber layer made of a rubber composition containing fluororubber are laminated.

[0008] According to the present invention, it is possible to provide a hose that can suppress adhesion between the outer surfaces of the hoses and has excellent compression set properties.

[0009] In other words, according to the present invention, since adhesion between the outer surfaces of the hoses can be suppressed, it is possible to provide a hose with excellent compression set properties while reducing the burden on workers and the risk of damage to the outer surface of the hose, without hindering storage or transportation.

[0010] Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to these embodiments.

[0011] In this specification, when "X to Y" (where X and Y are any numbers) is written, unless otherwise specified, it means "greater than or equal to X and less than or equal to Y," and also includes the meaning of "preferably greater than X" or "preferably less than Y." In this specification, for numerical ranges described in steps, the upper or lower limit of one step in the numerical range can be arbitrarily combined with the upper or lower limit of another step in the numerical range. In addition, in numerical ranges described in this specification, the upper or lower limit of that numerical range can be replaced with the values ​​shown in the examples. In this specification, "X and / or Y (where X and Y are any combination)" means at least one of X and Y, and can mean X only, Y only, or X and Y. Also, in this specification, "(meth)acrylic" refers to "acrylic" or "methacrylic."

[0012] The rubber composition for hoses of the present invention (hereinafter sometimes referred to as "this rubber composition for hoses") contains (A) an ethylene-(meth)acrylic acid ester binary copolymer, (B) an ethylene-(meth)acrylic acid ester-carboxyl group-containing monomer terpolymer, and (C) an organic peroxide crosslinking agent, characterized in that the mass ratio of component (A) to component (B) ((A) / (B)) is 95 / 5 to 50 / 50.

[0013] In the process of diligently studying how to suppress adhesion between the outer surfaces of hoses, the inventors conceived the idea of ​​reducing the tackiness of the outer surfaces of hoses by increasing the crosslinking density, and attempted to adjust the type of crosslinking agent and the amount of crosslinking agent. However, these methods failed to sufficiently reduce the tackiness of the outer surfaces of hoses, and moreover, sometimes adversely affected other properties (e.g., compression set resistance and scorch resistance). Based on these research results, the inventors further verified various formulations and newly discovered that by using (A) ethylene-(meth)acrylic acid ester binary copolymer and (B) ethylene-(meth)acrylic acid ester-carboxyl group-containing monomer terpolymer in combination, the tackiness of the outer surfaces of hoses is reduced, and adhesion between the outer surfaces of hoses tends to be significantly suppressed. Based on these new findings, the inventors conducted further studies to simultaneously satisfy the various properties required for various types of hoses. As a result, they discovered that by using (A) an ethylene-(meth)acrylic acid ester binary copolymer and (B) an ethylene-(meth)acrylic acid ester-carboxyl group-containing monomer terpolymer in combination, and by setting the blending ratio of the two within a specific range, the tackiness of the outer surface of the hose can be significantly reduced, adhesion between the outer surfaces of the hoses can be suppressed, and excellent compression set and scorch resistance can be achieved.

[0014] According to the present invention, by using this rubber composition for hoses, it is possible to significantly reduce the tackiness of the outer surface of the hose, suppress adhesion between the outer surfaces of the hoses, and provide a hose with excellent compression set properties, making it extremely useful.

[0015] Although the reason why the above-mentioned excellent effects are obtained with this rubber composition for hoses is not entirely clear, the inventors speculate that by using components (A) and (B) in specific proportions, the cohesive force in the rubber is moderately increased due to the presence of carboxyl group-containing monomer units in component (B) at a specific proportion, which significantly reduces the stickiness of the outer surface of the hose, suppresses sticking of the outer surfaces of the hoses together, and enables the achievement of excellent compression set properties.

[0016] Furthermore, the inventors investigated the processability of the rubber composition for hoses during manufacturing and found that the rubber composition for hoses, when using components (A) and (B) in combination, can sometimes have increased adhesion to metal extrusion jigs, for example, reducing the processability during hose manufacturing. From the viewpoint of improving the processability of the rubber composition for hoses, the inventors conducted further investigations into the conditions of processing aids to be added to the rubber composition containing components (A) and (B). As a result, they found that, among various processing aids, particularly by incorporating at least one of organopolysiloxane and alkylamine, it is possible to reduce the adhesion to metal extrusion jigs during hose manufacturing and achieve good processability.

[0017] Furthermore, after conducting further studies on organopolysiloxanes and alkylamines, the inventors discovered that by using a modified organopolysiloxane having vinyl groups at its termini, the adhesiveness reduction effect on the outer surface of the hose exhibited by the present invention is sufficiently maintained, while also providing excellent bloom resistance.

[0018] Therefore, in a preferred embodiment of the present invention, by including a modified organopolysiloxane having vinyl groups at its ends, the tackiness of the outer surface of the hose can be significantly reduced, preventing the outer surfaces of the hoses from sticking together. Furthermore, it is possible to provide a hose with excellent compression set properties, as well as good processability during hose manufacturing, high productivity, and a good appearance (resistance to bloom). This is extremely useful.

[0019] The following describes the various materials that make up the rubber composition for hoses.

[0020] (A) Ethylene-(meth)acrylic acid ester binary copolymer: Component (A) is a binary copolymer composed of ethylene and (meth)acrylic acid ester. These can be used alone or in combination of two or more.

[0021] The (meth)acrylic acid ester units in component (A) are constituent units derived from (meth)acrylic acid esters. Examples of (meth)acrylic acid esters include alkyl (meth)acrylic acid esters and alkoxyalkyl (meth)acrylic acid esters.

[0022] The alkyl (meth)acrylate esters mentioned above are not limited to the following, but include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate. The alkoxyalkyl (meth)acrylate esters mentioned above are not limited to the following, but include, for example, methoxymethyl (meth)acrylate, ethoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-propoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, and 4-methoxybutyl (meth)acrylate. These (meth)acrylate esters can be used alone or in combination of two or more.

[0023] The content of the above (meth)acrylic acid ester units is not particularly limited, but is, for example, 40% by mass or more, preferably 45 to 99% by mass, more preferably 50 to 97% by mass, and even more preferably 55 to 75% by mass, based on the total amount of component (A).

[0024] (A) Mooney viscosity of component (at 100°C, ml) １＋４The coefficient of viscosity (R) is not particularly limited, but for example, it is 10 to 40, preferably 19 to 32, and more preferably 19 to 29. The Mooney viscosity used herein is measured in accordance with the provisions of JIS K 6300-1:2013, using an L-shaped rotor, with a preheating time of 1 minute, a rotor rotation time of 4 minutes, and a test temperature of 100°C.

[0025] (B) Ethylene-(meth)acrylic acid ester-carboxyl group-containing monomer terpolymer. Component (B) is a terpolymer composed of ethylene, (meth)acrylic acid ester, and carboxyl group-containing monomer. These can be used individually or in combination of two or more.

[0026] The (meth)acrylic acid ester units in component (B) are constituent units derived from (meth)acrylic acid esters. Examples of (meth)acrylic acid esters include alkyl (meth)acrylic acid esters and alkoxyalkyl (meth)acrylic acid esters.

[0027] The alkyl (meth)acrylate esters mentioned above are not limited to the following, but include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate. The alkoxyalkyl (meth)acrylate esters mentioned above are not limited to the following, but include, for example, methoxymethyl (meth)acrylate, ethoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-propoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, and 4-methoxybutyl (meth)acrylate. These (meth)acrylate esters can be used alone or in combination of two or more.

[0028] The content of the above (meth)acrylic acid ester units is not particularly limited, but is, for example, 40% by mass or more, preferably 45 to 95% by mass, more preferably 50 to 90% by mass, and even more preferably 55 to 75% by mass, based on the total amount of component (B).

[0029] The above-mentioned carboxyl group-containing monomer units are constituent units derived from carboxyl group-containing monomers. Examples include acrylic acid, methacrylic acid, crotonic acid, 2-pentenoic acid, maleic acid, fumaric acid, itaconic acid, and unsaturated dicarboxylic acid monoesters. Examples of the above-mentioned unsaturated dicarboxylic acid monoesters include monoalkyl maleate, monoalkyl fumarate, monocyclohexyl maleate, and monocyclohexyl fumarate. More specifically, examples include mono-n-butyl maleate, monoethyl maleate, monomethyl maleate, mono-n-butyl fumarate, monoethyl fumarate, and monomethyl fumarate. These can be used individually or in combination of two or more.

[0030] The content of the above-mentioned carboxyl group-containing monomer units is not particularly limited, but is, for example, 0.5 to 10% by mass, preferably 1 to 7% by mass, on a total basis of component (B).

[0031] (B) Mooney viscosity of component (100°C, ML) １＋４ ) is not particularly limited, but for example, it is 10 to 50, preferably 13 to 41, and more preferably 13 to 19.

[0032] This rubber composition mainly contains component (A) and component (B) as polymer components. That is, the total content of component (A) and component (B) relative to the total amount of polymer components contained in this rubber composition (100% by mass) is 70% by mass or more, and may be 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass.

[0033] Furthermore, in this rubber composition, it is important to set the mass ratio of component (A) to component (B) ((A) / (B)) to 95 / 5 to 50 / 50, from the viewpoint of reducing the tackiness of the outer surface of the hose, suppressing sticking of the outer surfaces of the hoses to each other, and satisfying the compression set requirements. Outside of this range, the tackiness of the outer surface of the hoses is not sufficiently reduced, the outer surfaces of the hoses tend to stick to each other, and the compression set tends to be insufficient. The mass ratio ((A) / (B)) can be set appropriately within the above range, for example, 90 / 10 to 50 / 50, 80 / 20 to 55 / 45, 70 / 30 to 60 / 40, etc., but from the viewpoint of reducing the tackiness of the outer surface of the hoses, suppressing sticking of the outer surfaces of the hoses to each other, and satisfying the compression set requirements, 90 / 10 to 70 / 30 is preferred.

[0034] The content of component (A) is preferably 25 to 65% by mass, and more preferably 30 to 60% by mass, based on the total rubber composition for the hose (100% by mass). The content of component (A) can be appropriately set within the above range, and may be, for example, 40 to 60% by mass.

[0035] The content of component (B) is preferably 1.5 to 35% by mass, and more preferably 3 to 25% by mass, based on the total rubber composition for the hose (100% by mass). The content of component (B) can be appropriately set within the above range, and may be, for example, 5 to 20% by mass.

[0036] Commercially available products can be used for components (A) and (B), such as "Vamac ULTRA DX" and "Vamac G" (both manufactured by Celanese).

[0037] (C) Organic peroxide crosslinking agent This rubber composition for hoses contains (C) an organic peroxide crosslinking agent, which reduces the tackiness of the outer surface of the hose and suppresses sticking of the outer surfaces of the hoses together.Specifically, for example, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)cyclododecane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)octane, n-butyl-4,4-bis(t-butylperoxy)butane, n-butyl-4,4-bis(t-butylperoxy) Peroxyketals such as oxy(valerate), dialkylperoxides such as di-t-butylperoxide, dicumylperoxide, t-butylcumylperoxide, α,α'-bis(t-butylperoxy-m-isopropyl)benzene, α,α'-bis(t-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, acetylperoxide, isobutylylperoxide Diacyl peroxides such as octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, m-trioyl peroxide, and t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxylaurate, t-butyl peroxybenzoate, di-t-butyl peroxy Examples include peroxyesters such as buphthalates, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate, and cumylperoxyoctate, as well as hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, and 1,1,3,3-tetramethylbutylperoxide. These can be used individually or in combination of two or more.

[0038] The content of component (C) is preferably 0.8 to 2.5 parts by mass, more preferably 1 to 2 parts by mass, and still more preferably 1.5 to 2 parts by mass, per 100 parts by mass in total of component (A) and component (B). When a 100% pure raw material is not used as the organic peroxide crosslinking agent, the raw material is formulated such that the ratio in terms of raw material equivalent falls within the above range.

[0039] (Other Components) In addition to the above components, the rubber composition for hoses may appropriately contain additives such as other crosslinking agents, co-crosslinking agents, processing aids, fillers, and anti-aging agents. These may be used alone or in combination of two or more thereof.

[0040] <Diamine-based Crosslinking Agent> The rubber composition for hoses may optionally contain, for example, a diamine-based crosslinking agent within a range that does not inhibit the effects of the present invention. Examples thereof include aliphatic polyamines such as ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetraamine, and hexamethylenetetramine; aromatic polyamines such as p-phenylenediamine, cumenediamine, and N,N'-dicinnamylidene-1,6-hexanediamine; and amine carbamates such as ethylenediamine carbamate and hexamethylenediamine carbamate. These may be used alone or in combination of two or more thereof.

[0041] The content of the diamine-based crosslinking agent is not particularly limited, but is preferably 0.1 to 1 part by mass, more preferably 0.2 to 0.5 part by mass, per 100 parts by mass in total of component (A) and component (B). However, from the viewpoint of scorch resistance, a lower content of the diamine-based crosslinking agent is preferable. For example, the content is preferably less than 0.3 parts by mass, more preferably less than 0.1 parts by mass, and may be, for example, 0 parts by mass, per 100 parts by mass in total of component (A) and component (B).

[0042] (D) Co-crosslinking agent The rubber composition for this hose preferably contains a co-crosslinking agent in order to more significantly reduce the tackiness of the outer surface of the hose and suppress the adhesion between the outer surfaces of the hoses. Examples of co-crosslinking agents include polyfunctional monomers, maleimide compounds, quinone compounds, and sulfur-containing compounds. Examples of the polyfunctional monomers include divinylbenzene, ethylene glycol dimethacrylate, diallyl phthalate, trimethylolpropane trimethacrylate, triallyl cyanurate, triallyl isocyanurate (TAIC), triallyl trimellitate, and triallyl tricyanurate. Examples of the maleimide compounds include N,N'-m-phenylenebismaleimide and toluenebismaleimide. Examples of the quinone compounds include quinone dioxime and dibenzoyl-p-quinone dioxime. Examples of the sulfur-containing compounds include sulfur, dipentamethylenethuram tetrasulfide, and mercaptobenzothiazole.

[0043] From the viewpoint of significantly achieving the effects of the present invention, the content of component (D) is preferably, for example, 1 to 8 parts by mass, and more preferably 1.5 to 5 parts by mass, based on 100 parts by mass of the total of components (A) and (B).

[0044] (E) Processing aids: Examples of processing aids include higher fatty acids such as stearic acid; higher fatty acid amides such as stearic acid amide; aliphatic higher amines such as alkylamines having 4 to 30 carbon atoms; aliphatic higher alcohols such as stearyl alcohol; partial esters of fatty acids and polyhydric alcohols such as glycerin fatty acid esters; fatty acid metal salts such as zinc stearate; organopolysiloxanes such as dimethylpolysiloxane, methylvinylpolysiloxane, methylphenylpolysiloxane, and modified organopolysiloxanes having functional groups at their ends; and so on.

[0045] Among the components (E), aliphatic higher amines and organopolysiloxanes are preferred. That is, the rubber composition for hoses of the present invention may have increased adhesiveness to metal extrusion jigs and decrease processability, which is caused by the combined use of the component (A) and the component (B), and particularly due to the affinity between the carboxy group-containing monomer units of the component (B) and the metal constituting the extrusion jig. However, by blending the aliphatic higher amine and the organopolysiloxane, the interaction between the carboxy group-containing monomer units and the metal constituting the extrusion jig can be inhibited, and the adhesiveness to the metal extrusion jig is reduced, so that good processability can be achieved.

[0046] As the aliphatic higher amine, stearylamine is preferred from the viewpoint of remarkably exhibiting the above effects. As the organopolysiloxane, a modified organopolysiloxane having an amino group or a vinyl group at the terminal is preferred. Among these, a modified organopolysiloxane having a vinyl group at the terminal is particularly preferred because it does not adversely affect the effect of reducing the adhesiveness of the outer peripheral surface of the hose obtained by the combined use of the component (A) and the component (B), and is further excellent in blooming resistance.

[0047] The content of the component (E) is, for example, 0.3 to 5 parts by mass, preferably 0.5 to 3 parts by mass, more preferably 0.8 to 2.5 parts by mass, relative to 100 parts by mass in total of the component (A) and the component (B). Further, the content of the organopolysiloxane and / or stearylamine is, for example, 0.3 to 3 parts by mass, preferably 0.5 to 2 parts by mass, more preferably 0.8 to 1.5 parts by mass, relative to 100 parts by mass in total of the component (A) and the component (B).

[0048] (Filler) Examples of the filler include carbon black, silicon dioxide, calcium carbonate, talc, clay and the like. Among these, carbon black is preferred.

[0049] Examples of carbon black include those of SAF grade, ISAF grade, HAF grade, MAF grade, FEF grade, GPF grade, SRF grade, FT grade, MT grade and the like. Among these, MAF grade is preferred.

[0050] The specific surface area for nitrogen adsorption of carbon black is, for example, 10 to 150 m². 2 A value of / g is preferred, and more preferably 15 to 100 m 2 / g, more preferably 20 to 80m 2 / g, also 30-60m 2 It may also be expressed as / g. The specific surface area of ​​nitrogen adsorption of carbon black can be measured in accordance with the method described in JIS K 6217-2:2017.

[0051] The amount of iodine adsorbed by carbon black is preferably, for example, 10 to 150 mg / g, more preferably 10 to 75 mg / g, even more preferably 20 to 65 mg / g, and may also be 30 to 60 mg / g. The amount of DBP (dibutyl phthalate) absorbed by carbon black is preferably, for example, 20 to 180 mL / 100g, more preferably 20 to 150 mL / 100g. The iodine adsorbed by carbon black is a value measured in accordance with JIS K 6217-1 (Method A):2017, and the DBP absorbed by carbon black is a value measured in accordance with JIS K 6217-4:2017.

[0052] The content of the filler is not particularly limited, but for example, it may be 30 to 100 parts by mass, 35 to 95 parts by mass, 40 to 90 parts by mass, 45 to 85 parts by mass, or 45 to 80 parts by mass per 100 parts by mass of the total of components (A) and (B).

[0053] (Anti-aging agents) Examples of anti-aging agents include carbamate-based, phenylenediamine-based, phenol-based, diphenylamine-based, and quinoline-based anti-aging agents, as well as waxes. These can be used individually or in combination of two or more. The content of the anti-aging agent is not particularly limited, but for example, it is about 1 to 10 parts by mass and 1.5 to 8 parts by mass per 100 parts by mass of the total of components (A) and (B).

[0054] (Preparation Method) This rubber composition for hoses can be obtained, for example, by mixing components (A) to (C) above with other additives as needed, and kneading them using a kneader such as a roll, kneader, or Banbury mixer.

[0055] (Method for manufacturing a hose) As a method for manufacturing a hose using this rubber composition for hoses, for example, in the case of a single-layer structure, the above-mentioned rubber composition for hoses is used to extrude into a tubular shape onto a mandrel, and the uncrosslinked rubber hose extruded onto the mandrel is crosslinked with pressurized steam, and then the mandrel is removed to manufacture the desired hose. Although the above describes a single-layer hose having a single rubber layer, this rubber composition for hoses is not limited to this and can also be suitably used as a material for forming multilayer (multi-layer) hoses with two or more layers. For example, a hose with a layered structure in which a rubber layer made of a crosslinked material of this rubber composition for hoses and a rubber layer made of a crosslinked material of a rubber composition containing fluororubber are laminated is preferred. Specifically, a hose with a layered structure in which a rubber layer made of a crosslinked material of this rubber composition for hoses is laminated to the outer surface of a rubber layer made of a crosslinked material of a rubber composition containing fluororubber is preferred, and a hose in which the rubber layer made of a crosslinked material of this rubber composition for hoses is the outermost layer is preferred.

[0056] For example, an inner layer rubber composition and an outer layer rubber composition (e.g., the rubber composition for this hose) are prepared. These are then co-extruded, crosslinked with pressurized steam under predetermined conditions (e.g., 160°C for 45 minutes), and then secondary crosslinked in an oven under predetermined conditions (e.g., 150°C for 8 hours). As a result, the outer layer is laminated onto the outer surface of the inner layer, and a multi-layer hose can be obtained.

[0057] Furthermore, in one embodiment of the present invention, the hose may have at least one (single layer) of rubber made of the rubber composition for hoses. However, when forming a hose with a multi-layer structure of two or more layers, it is preferable that the outermost layer be made of the rubber composition for hoses from the viewpoint of exhibiting the effects of the present invention. The composition of other rubber layers adjacent to the inside of the rubber layer made of the rubber composition for hoses is not particularly limited, but for example, a rubber layer made of a rubber composition containing fluororubber can be used. Specifically, for example, a layer structure may be provided in which a rubber layer made of the rubber composition for hoses is located on the outer circumference of a rubber layer made of a rubber composition containing fluororubber. The rubber composition containing fluororubber is not particularly limited, but fluororubber may be used as the main component of the polymer component (50 to 100% by mass of the polymer component), or fluororubber and ethylene acrylic rubber may be used in combination.

[0058] Examples of the above-mentioned fluororubber (FKM) include VdF-based fluororubbers such as vinylidene fluoride (VdF)-hexafluoropropylene (HFP) systems, VdF-tetrafluoroethylene (TFE)-HFP systems, and VdF-chlorotrifluoroethylene (CTFE) systems, as well as TFE-propylene (Pr) systems, HFP-ethylene systems, VdF-perfluoro(alkyl vinyl ether) (PAVE) systems, TFE-PAVE systems, fluorosilicone rubber, fluorophosphazene rubber, and fluorine-containing thermoplastic elastomers.

[0059] The ethylene acrylic rubber used in combination with the above-mentioned fluororubber is not particularly limited, and components (A) and (B) used in this hose rubber composition may be used as appropriate.

[0060] In one preferred embodiment of the present invention, a hose having an inner layer made of a rubber composition containing fluororubber and ethylene acrylic rubber, and an outermost layer made of the rubber composition for this hose, exhibits the effect of reducing the tackiness of the outer surface of the hose and suppressing sticking between the outer surfaces of the hoses, while also having excellent interlayer adhesion.

[0061] The inner diameter, thickness, and length of a hose obtained using this rubber composition for hoses are not particularly limited, but for example, in the case of a single-layer hose, the inner diameter is preferably in the range of 5.0 to 25.0 mm and the thickness is preferably in the range of 2.0 to 5.0 mm. In the case of a multi-layer hose, although not particularly limited, the inner diameter of the rubber layer made of this rubber composition for hoses is preferably in the range of 5.0 to 25.0 mm and the thickness is preferably in the range of 2.0 to 5.0 mm.

[0062] (Applications) This rubber composition for hoses can be used for various types of hoses, such as all types of hoses that require heat resistance. For example, it is useful as an air system hose for automobiles, such as an air system hose that discharges an air mixture containing gasoline vapor or engine oil mist from the engine and supplies it to the engine for re-combustion, or as a fuel system hose. Specifically, the heat-resistant hose of the present invention can be suitably used as an automobile heat-resistant hose such as a fuel hose, air hose, turbo air hose (air hose for superchargers), vacuum brake hose, common rail diesel fuel hose, and DPF (diesel particulate filter) sensor hose. In addition, the heat-resistant hose of the present invention can be used not only as an automobile heat-resistant hose, but also as a heat-resistant hose for construction machinery, ships, and aircraft.

[0063] Next, embodiments of the present invention will be described together with comparative examples. However, the present invention is not limited to these embodiments.

[0064] First, prior to the examples and comparative examples, the following materials were prepared.

[0065] [(A) Ethylene-methyl acrylate binary copolymer] ・Vamac ULTRA DX (manufactured by Celanese, ethylene-methyl acrylate binary copolymer)

[0066] [(B) Ethylene-acrylic acid ester-carboxyl group-containing monomer terpolymer] ・Vamac G (manufactured by Celanese, ethylene-methyl acrylate-vinyl carboxylate monomer terpolymer)

[0067] [(C) Organic peroxide crosslinking agent] Perhexa 25B-40 (manufactured by NOF Corporation, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane)

[0068] [(D) Co-crosslinking agent] ・TAIC-M60 (manufactured by Mitsubishi Chemical Corporation, triallyl isocyanurate)

[0069] [(E) Processing aids] ・Organopolysiloxane (HT600DL, manufactured by Structol, reactive organosilicone derivative) ・Stearylamine stearic acid

[0070] (Other ingredients) ・Carbon black (FEF grade)

[0071] [Examples 1-8, Comparative Examples 1-3] The above components were blended in the proportions shown in Table 1 below, and kneaded using a mixing roll to produce a rubber composition for hoses. The outer layer rubber composition and the inner layer rubber composition made from this hose rubber composition were co-extruded, and after steam crosslinking at 160°C for 45 minutes, secondary crosslinking was performed in an oven at 150°C for 8 hours to produce a heat-resistant hose (inner diameter 15 mm, outer diameter 21 mm) in which the outer layer (thickness 2 mm) was directly formed on the outer surface of the inner layer (thickness 1 mm). Each property was evaluated according to the following criteria. The results are shown in Table 1 below.

[0072] The above-mentioned inner layer rubber composition contains 70 parts by mass of fluororubber (FKM), 30 parts by mass of ethylene acrylic rubber (AEM), 30 parts by mass of carbon black, and 1.5 parts by mass of an organic peroxide crosslinking agent, and is prepared by kneading using a mixing roll.

[0073] ≪Hose Outer Surface Adhesion Confirmation Test≫ After heating the fabricated hoses (30 cm in length) to 40°C, six hoses were stacked in a cylindrical shape and left at room temperature for one week. Then, one hose was removed, and the adhesion between the hoses was checked and evaluated according to the following criteria. [Evaluation Criteria] ○ (very good) ... When one hose is held, the other hoses do not lift, and there is no damage to the contact area. △ (good) ... When one hose is held, the other hoses do not lift, but there is damage to the contact area. × (poor) ... When one hose is held, it becomes one with the remaining hoses and lifts up as well.

[0074] <Compression Set Test> Large test specimens were prepared in accordance with JIS K 6262:2013 using each hose rubber composition by hot pressing at 160°C for 45 minutes. The compression set rate (%) after heat aging at 150°C for 72 hours was determined for the obtained test specimens in accordance with JIS K 6262:2013 and evaluated according to the following criteria. [Evaluation Criteria] ○ (very good) ... 30% or less △ (good) ... greater than 30% and 40% or less × (poor) ... greater than 40%

[0075] <<Scorch Resistance Test>> For each rubber composition for hoses, in accordance with JIS K 6300:2013, an L-shaped rotor was used, preheated to a test temperature of 121°C for 1 minute, and then the rotor was rotated. The time (t5) [minutes] at which the viscosity increased by 5 Mooney units from the minimum Mooney viscosity was measured. The Mooney scorch time (t5) was evaluated according to the following criteria: [Evaluation Criteria] ○ (very good) ... 45 minutes or more △ (good) ... 20 minutes or more but less than 45 minutes × (poor) ... less than 20 minutes

[0076] ≪Adhesion Test to Extruder Fittings (Productivity Test)≫ The ease of handling when disassembling the extruder head after hose extrusion molding was used as the evaluation indicator. The following criteria were used for evaluation. [Evaluation Criteria] ○ (very good) ... No rubber adhesion. △ (good) ... Rubber adhesion is present, but can be removed by the worker. × (poor) ... Rubber adhesion is present, and cannot be removed by the worker.

[0077] ≪Interlaminar Adhesion Test (against Fluororubber Layer)≫ A 25 mm wide test piece was cut from the fabricated hose, and the outer layer of the test piece was peeled off at a speed of 50 mm per minute using a tensile testing machine. The fracture state at that time was observed and evaluated according to the following criteria. [Evaluation Criteria] ○ (very good) ... Base material failure △ (good) ... Partial base material failure × (poor) ... Interfacial delamination

[0078]

[0079] As shown in Table 1 above, the rubber compositions for hoses of Examples 1 to 8 of the present invention all suppressed adhesion between the outer surfaces of the hoses and exhibited excellent compression set properties.

[0080] In contrast, the comparative examples that did not meet the requirements of the present invention either failed to suppress adhesion between the outer surfaces of the hoses or had insufficient compression set properties. Specifically, the rubber composition for hoses in Comparative Example 1 did not contain component (B), resulting in an inability to suppress adhesion between the outer surfaces of the hoses. Furthermore, although the rubber compositions for hoses in Comparative Examples 2 and 3 contained components (A) and (B), their mass ratio ((A) / (B)) was outside the specified range of the present invention, resulting in inferior compression set properties.

[0081] As shown above, this hose rubber composition, which contains components (A) to (C) and has a mass ratio of component (A) to component (B) of 95 / 5 to 50 / 50, is found to suppress hose sticking together and also exhibits excellent compression set properties.

[0082] Furthermore, from the results of Example 5, it was found that a particularly preferred range for the content of (C) organic peroxide crosslinking agent is 1 part by mass or more, for example, about 1 to 2 parts by mass.

[0083] Furthermore, the results from Example 8 showed that including at least one of organopolysiloxane and alkylamine suppresses adhesion to extrusion fittings and improves productivity.

[0084] While the above embodiments illustrate specific forms of the present invention, these embodiments are merely illustrative and should not be interpreted restrictively. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention.

[0085] The rubber composition for hoses of the present invention can be used for various types of hoses, such as all types of hoses that require heat resistance. For example, it is useful as an air system hose for automobiles, such as an air system hose that discharges an air mixture containing gasoline vapor or engine oil mist from the engine and supplies it to the engine for re-combustion, or as a fuel system hose. Specifically, the heat-resistant hose of the present invention can be suitably used as an automobile heat-resistant hose such as a fuel hose, air hose, turbo air hose (air hose for superchargers), vacuum brake hose, common rail diesel fuel hose, and DPF (diesel particulate filter) sensor hose. In addition, the heat-resistant hose of the present invention can be used not only as an automobile heat-resistant hose, but also as a heat-resistant hose for construction machinery, ships, and aircraft.

Claims

1. A rubber composition for hoses containing the following components (A) to (C), wherein the mass ratio of component (A) to component (B) ((A) / (B)) is 95 / 5 to 50 / 50. (A) Ethylene-(meth)acrylic acid ester binary copolymer (B) Ethylene-(meth)acrylic acid ester-carboxyl group-containing monomer terpolymer (C) Organic peroxide crosslinking agent 2. The rubber composition for hoses according to claim 1, wherein the content of component (C) is 0.8 to 2.5 parts by mass per 100 parts by mass of the total of component (A) and component (B).

3. The rubber composition for hoses according to claim 1 or 2, further comprising (D) a cocrosslinking agent.

4. The rubber composition for hoses according to any one of claims 1 to 3, further comprising at least one of an organopolysiloxane and an alkylamine.

5. The rubber composition for hoses according to any one of claims 1 to 4, further comprising a modified organopolysiloxane having vinyl groups at its ends.

6. A hose comprising a layered structure in which a rubber layer made of a hose rubber composition according to any one of claims 1 to 5 and a rubber layer made of a fluororubber-containing rubber composition are laminated.

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