Rubber composition for extruded hoses, and hoses

Abstract

In a rubber composition for extruded hoses, the deterioration of swell caused by the combined use of recycled carbon black and non-recycled carbon black is suppressed, and deterioration of extrusion length and extrusion volume is also suppressed. [Solution] A rubber composition for extruded hoses containing the following components (A) to (C). (A) Rubber component (B) Recycled carbon black with DBP absorption of 70-170 ml / 100g (C) Non-recycled carbon black with DBP absorption of 50-160 ml / 100g

Description

[Technical Field]

[0001] The present invention relates to a rubber composition for extruded hoses suitable for extrusion molding, and to a hose made from the rubber composition for extruded hoses. [Background technology]

[0002] In recent years, recycled carbon black has attracted attention from the perspective of resource conservation and environmental protection. Specifically, with the aim of achieving carbon neutrality (CO2 reduction), there is consideration to replacing non-recycled carbon black (virgin carbon black, vCB) with recycled carbon black (rCB) obtained by thermally decomposing waste tires and other materials.

[0003] For example, Patent Document 1 describes a tire rubber composition comprising diene rubber, recycled carbon black, and non-recycled carbon black. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-146475 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] As mentioned above, from the perspective of resource conservation and environmental protection, attempts are being made to replace some of the non-recycled carbon black used in rubber compositions for tires and other applications with recycled carbon black, and to use both in combination. The inventors have diligently researched rubber compositions for extruded hoses in particular among various rubber compositions. In the course of this research, when comparing rubber compositions for extruded hoses using recycled carbon black alone with rubber compositions for extruded hoses using non-recycled carbon black alone, the inventors' investigations revealed that the swell (wall thickness and outer diameter) during extrusion molding was equivalent and no difference was observed. However, when recycled carbon black and non-recycled carbon black were used in combination, the swell during extrusion molding deteriorated.

[0006] This invention was made in view of new problems revealed through the inventors' studies, and provides a rubber composition for extruded hoses that can suppress the deterioration of swell caused by the combined use of recycled carbon black and non-recycled carbon black. [Means for solving the problem]

[0007] The inventors diligently conducted research to solve the above problems. In the course of this research, they discovered that by using recycled carbon black and non-recycled carbon black that satisfy specific conditions among various types of carbon black, it is possible to obtain a rubber composition for extruded hoses that can suppress the deterioration of swell caused by the combined use of both.

[0008] The present invention discloses the following inventions [1] to [5], but is not limited to these. [1] A rubber composition for extruded hoses containing the following components (A) to (C). (A) Rubber component (B) Recycled carbon black with DBP absorption of 70-170 ml / 100g (C) Non-recycled carbon black with DBP absorption of 50-160 ml / 100g [2] The rubber composition for extruded hoses described in [1], wherein the above component (C) is non-recycled carbon black with a DBP absorption amount of 80 to 160 ml / 100 g. [3] The rubber composition for extruded hoses according to [1] or [2], wherein the mass ratio (B / C) of component (B) to component (C) is 10 / 90 to 90 / 10. [4] The rubber composition for extruded hoses according to any one of [1] to [3], wherein the total amount of carbon black contained in the above extruded hose rubber composition (total amount of component (B) and component (C)) is 100 parts by mass or more per 100 parts by mass of component (A). [5] A hose made of a rubber composition for extruded hoses as described in any of [1] to [4]. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a rubber composition for extruded hoses that can suppress the deterioration of swell caused by the combined use of non-recycled carbon black and recycled carbon black.

[0010] Furthermore, according to one embodiment of the present invention, it is possible to suppress the deterioration of swell caused by the combined use of non-recycled carbon black and recycled carbon black, and to further improve the balance between swell, discharge volume, and discharge length. [Brief explanation of the drawing]

[0011] [Figure 1] This is a diagram showing an example of a hose according to the present invention. [Modes for carrying out the invention]

[0012] Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described below.

[0013] In this specification, "X and / or Y (X and Y are arbitrary configurations)" means at least one of X and Y, and includes three cases: only X, only Y, and X and Y. Also, in this specification, when expressing "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it means "X or more and Y or less", and also includes the meaning of "preferably exceeding X" or "preferably less than Y". Regarding the numerical ranges described stepwise in this specification, the upper limit value or lower limit value of a numerical range at a certain step can be arbitrarily combined with the upper limit value or lower limit value of a numerical range at another step. Also, in the numerical ranges described in this specification, the upper limit value or lower limit value of the numerical range can be replaced with the values shown in the test examples.

[0014] <<Rubber Composition for Extruded Hose>> The present invention relates to a rubber composition for an extruded hose supplied to an extruder, and provides a rubber composition for an extruded hose capable of suppressing the deterioration of swell caused by the combined use of recycled carbon black and non-recycled carbon black. Specifically, the present invention provides, for example, a rubber composition for an extruded hose (hereinafter sometimes referred to as "this rubber composition") containing a rubber component, recycled carbon black having a DBP absorption of 70 to 170 ml / 100 g, and non-recycled carbon black having a DBP absorption of 50 to 160 ml / 100 g.

[0015] As described above, when comparing a rubber composition for an extruded hose using recycled carbon black alone as the carbon black with a rubber composition for an extruded hose using non-recycled carbon black alone as the carbon black, the swell during extrusion is the same and no difference is observed. On the other hand, when recycled carbon black and non-recycled carbon black are used in combination, it has been revealed by the study of the present inventors that, unexpectedly, the swell during extrusion deteriorates.

[0016] The inventors then conducted further research to solve these new problems and found that a rubber composition for extruded hoses containing a rubber component, recycled carbon black with a DBP absorption rate of 70-170 ml / 100g, and non-recycled carbon black with a DBP absorption rate of 50-160 ml / 100g can solve the above problems. Furthermore, the inventors have found that a rubber composition for extruded hoses containing recycled carbon black with a DBP absorption rate of 70-170 ml / 100g and non-recycled carbon black with a DBP absorption rate of 50-160 ml / 100g not only suppresses the deterioration of swell, but also improves the balance between swell, discharge volume, and discharge length.

[0017] The inventors of the present invention surmise that the reason the above problems occur is that when recycled carbon black is used alone or when non-recycled carbon black is used alone, the internal pressure during extrusion tends to be uniformly distributed, whereas when both are used in combination, the internal pressure tends to be uneven, resulting in a deterioration of swell. The inventors of the present invention surmise that the reason why the above problems can be solved and the excellent effects are not entirely clear is that the appropriate structure of certain non-recycled carbon black improves the transport force during extrusion molding through interaction with recycled carbon black, etc., thereby improving swell. In other words, the inventors surmise that non-recycled carbon black with a DBP absorption amount of 50-160 ml / 100g, which is an indicator that reflects the structure of carbon black, acts complementaryly with recycled carbon black with a DBP absorption amount of 70-170 ml / 100g, forming an appropriate three-dimensional network within the rubber matrix and contributing to the improvement of transport force during extrusion molding. For example, non-recycled carbon black with a DBP absorption of less than 50 ml / 100g is thought to have an insufficient structure, resulting in poor contact between carbon black particles and between carbon black particles and rubber. This makes it difficult to contribute to flow stabilization and suppression of elastic recovery, leading to high extrusion resistance and a tendency for swell to worsen. Conversely, non-recycled carbon black with an excessively developed structure is thought to have an excessive aggregate skeleton between particles, reducing dispersibility in the rubber matrix, inhibiting fluidity, and worsening extrusion resistance and swell. On the other hand, non-recycled carbon black with a DBP absorption of 50-160 ml / 100g is thought to possess an appropriate void skeleton and specific surface area. This interacts with the skeleton structure and surface properties of recycled carbon black, appropriately and efficiently transmitting shear stress in the extrusion path, stabilizing the discharge behavior, suppressing elastic recovery after passing through the die, and improving swell.

[0018] In conventional research and development, the problem of swell deterioration due to the combined use of non-recycled carbon black and recycled carbon black has not yet been reported. Furthermore, the technical concept of solving the above problem by using carbon black having a specific range of DBP absorption, as in the present invention, is completely unknown. Therefore, the usefulness of the rubber composition for extruded hoses according to the present invention is extremely high. Embodiments of the present invention will be described in detail below.

[0019] [(A) Rubber component] The rubber components used in this rubber composition are not particularly limited, but examples include diene rubbers such as natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), isoprene rubber (IR), and acrylonitrile-butadiene rubber (NBR), and non-diene rubbers such as ethylene-propylene rubber (EPM), ethylene-propylene-diene ternary copolymer (EPDM), butyl rubber (IIR), and acrylic rubber (ACM). These can be used individually or in combination of two or more.

[0020] Among the rubber components mentioned above, in one example of the embodiments of this rubber composition, ethylene-propylene rubber such as EPDM and EPM is preferred, and EPDM is particularly preferred. Furthermore, in one example of the embodiments of this rubber composition, (A) rubber component is preferably mainly composed of ethylene-propylene rubber, and is particularly preferably mainly composed of EPDM. The term "main component" above refers to a component that accounts for 50% or more by mass of the total rubber components (100% by mass) contained in this rubber composition, preferably 55% or more by mass, more preferably 60% or more by mass, and even more preferably 70% or more by mass. It may also be 80% or more by mass, 90% or more by mass, 95% or more by mass, or even 100% by mass.

[0021] The ethylene content of EPDM is not particularly limited, but is preferably 48-70% by mass, and more preferably 50-62% by mass. The propylene content of EPDM is not particularly limited, but is preferably 22-46% by mass, and more preferably 30-44% by mass.

[0022] The content of the diene monomer used as the third component constituting EPDM is not particularly limited, but is preferably 3 to 11% by mass, and more preferably 3.5 to 6% by mass.

[0023] The diene monomer used as the third component of EPDM is not particularly limited, but diene monomers having 5 to 20 carbon atoms are preferred. Specifically, examples include 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 2,5-dimethyl-1,5-hexadiene, 1,4-octadiene, 1,4-cyclohexadiene, cyclooctadiene, dicyclopentadiene (DCP), 5-ethylidene-2-norbornene (ENB), and 5-butylidene-2-norbornene. These can be used individually or in combination of two or more. Among these, DCP and ENB are preferred.

[0024] Mooney viscosity of EPDM (ML) 1+4 The temperature (125°C) is not particularly limited, but is preferably 30 to 110°C, and more preferably 60 to 90°C.

[0025] Furthermore, in one example of the embodiments of this rubber composition, (A) the rubber component may be mainly composed of acrylonitrile-butadiene rubber (NBR). The meaning of "main component" is the same as described above.

[0026] The amount of acrylonitrile (AN) in NBR is not particularly limited, but is preferably 18 to 50% by mass, and more preferably 20 to 42% by mass.

[0027] NBR Mooney viscosity (ML) 1+4The temperature (up to 100°C) is not particularly limited, but for example, 40 to 82°C is preferred, more preferably 48 to 80°C, and even more preferably 50 to 78°C.

[0028] (A) The content of the rubber component is not particularly limited, but is, for example, 20% by mass or more, preferably 22% by mass or more, more preferably 22-60% by mass, and may be 24-50% by mass, etc., relative to the rubber composition (100% by mass).

[0029] Furthermore, in one example of the embodiment of the present invention, the EPDM content is not particularly limited, but is, for example, 20% by mass or more, preferably 22% by mass or more, more preferably 22-60% by mass, and may be 24-50% by mass, etc., relative to the rubber composition (100% by mass).

[0030] Furthermore, in one embodiment of the present invention, the NBR content is not particularly limited, but is, for example, 30% by mass or more, preferably 35% by mass or more, more preferably 40-80% by mass, and may be 40-70% by mass, relative to the rubber composition (100% by mass).

[0031] [(B) Recycled carbon black] Recycled carbon black, also known as "rCB (recovered carbon black)," is carbon black obtained by recovering it from raw materials that are waste materials used for recycling. As recycled carbon black, it can be obtained by thermally decomposing carbon black-containing rubber products such as waste tires, industrial conveyor belts, power transmission belts, and rubber hoses using known methods. It should be noted that, unlike non-recycled carbon black, recycled carbon black does not have functional groups on its surface, and is therefore known to have poor interaction with rubber components.

[0032] It is important that the DBP (dibutyl phthalate) absorption of the recycled carbon black used in this rubber composition is within a specific range of 70 to 170 ml / 100g. By controlling the DBP absorption of both the recycled carbon black and the non-recycled carbon black within this specific range, the deterioration of swell described above can be suppressed, and the balance between swell, discharge volume, and discharge length can be improved. The DBP absorption of the recycled carbon black can be appropriately set within the above range; for example, 85 to 105 ml / 100g is preferred, and it may also be 85 to 100 ml / 100g, 88 to 100 ml / 100g, etc. The DBP absorption of carbon black is measured in accordance with JIS K6217-4:2017.

[0033] Recycled carbon black is produced by burning waste tires, industrial conveyor belts, power transmission belts, and carbon black-containing rubber products such as rubber hoses, and therefore contains ash derived from rubber components. The ash content is typically 2 to 20% by mass, preferably 5 to 20% by mass, more preferably 10 to 20% by mass, and may also be 15 to 17% by mass. The ash content can be measured according to the method compliant with JIS K6218-2:2005. This ash content consists of particles compounded with carbon black in recycled carbon black. While the particle size varies, it can be broadly classified into three categories: less than 1 μm, around 10 μm, and over 100 μm. The average particle size of the recycled carbon black is not particularly limited, but from the viewpoint of significantly achieving the effects of the present invention, for example, 100-500 nm is preferred, and more preferably 100-300 nm. The average particle size of the carbon black is the number-average particle size and is measured using a transmission electron microscope.

[0034] The specific surface area for nitrogen adsorption of recycled carbon black is not particularly limited, but from the viewpoint of significantly demonstrating the effects of the present invention, for example, 25 to 100 m² is recommended. 2 The value is / g, preferably 40-90m 2 / g, more preferably 50-80m 2The value is / g. The nitrogen adsorption specific surface area is measured, for example, by degassing the sample at 200°C for 15 minutes, and then using a mixed gas (N2: 70%, He: 30%) as the adsorbed gas, with a nitrogen adsorption specific surface area analyzer (e.g., Microdata 4232-II).

[0035] The amount of iodine adsorbed by recycled carbon black is not particularly limited, but is, for example, 25 to 100 g / kg, preferably 30 to 90 g / kg. The amount of iodine adsorbed by carbon black is measured in accordance with JIS K6217-1:2008 (Method A).

[0036] The amount of recycled carbon black is, for example, 5 to 200 parts by mass or 10 to 200 parts by mass per 100 parts by mass of (A) rubber component, preferably 20 to 180 parts by mass, more preferably 30 to 170 parts by mass, even more preferably 40 to 160 parts by mass, and particularly preferably 50 to 150 parts by mass, and may also be 10 to 100 parts by mass, 60 to 120 parts by mass, etc. Furthermore, in one embodiment of the present invention, the recycled carbon black content is, for example, 5 to 100 parts by mass, preferably 10 to 90 parts by mass, more preferably 15 to 80 parts by mass, and even more preferably 20 to 70 parts by mass, per 100 parts by mass of (A) rubber component, and may also be 10 to 100 parts by mass, 20 to 50 parts by mass, etc.

[0037] [(C) Non-recycled carbon black] Non-recycled carbon black, also known as "vCB (Virgin Carbon Black)," is carbon black that is directly manufactured using hydrocarbons such as coal as raw materials; in other words, it is carbon black that is not recycled. Examples of non-recycled carbon black include petroleum-derived carbon black. Examples include furnace black (furnace carbon black) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black (acetylene carbon black); thermal black (thermal carbon black) such as FT and MT; channel black (channel carbon black) such as EPC, MPC, and CC; and graphite. These can be used individually or in combination of two or more types.

[0038] It is important that the DBP (dibutyl phthalate) absorption of the non-recycled carbon black used in this rubber composition is within a specific range of 50 to 160 ml / 100g. By controlling the DBP absorption of both recycled and non-recycled carbon black within a specific range, the deterioration of swell described above can be suppressed, and the balance between swell, discharge volume, and discharge length can be improved. The DBP absorption of non-recycled carbon black can be appropriately set within the above range, preferably 80 to 160 ml / 100g, more preferably 90 to 160 ml / 100g, and even more preferably 100 to 160 ml / 100g, or 110 to 160 ml / 100g, 120 to 160 ml / 100g, etc. The DBP absorption of carbon black is measured in accordance with JIS K6217-4:2017.

[0039] The average particle size of non-recycled carbon black is not particularly limited, but is preferably 10 to 120 nm, more preferably 20 to 100 nm, and even more preferably 30 to 70 nm. The average particle size of carbon black is the number-average particle size and is measured by a transmission electron microscope.

[0040] The specific surface area for nitrogen adsorption of non-recycled carbon black is not particularly limited, but for example, it is 20 to 140 m². 2 The value is / g, preferably 30-100m 2 / g, more preferably 40-90m 2 The value is / g. The nitrogen adsorption specific surface area is measured, for example, by degassing the sample at 200°C for 15 minutes, and then using a mixed gas (N2: 70%, He: 30%) as the adsorbed gas, with a nitrogen adsorption specific surface area analyzer (e.g., Microdata 4232-II).

[0041] The amount of iodine adsorbed by non-recycled carbon black is not particularly limited, but for example, it is 20 to 160 mg / g, preferably 30 to 100 mg / g, and more preferably 40 to 90 mg / g. The amount of iodine adsorbed by carbon black is measured in accordance with JIS K6217-1:2008 (Method A).

[0042] As mentioned above, recycled carbon black contains ash derived from rubber components, while non-recycled carbon black contains almost no ash. The ash content in non-recycled carbon black is typically 0.5% by mass or less, 0.3% by mass or less, or 0.1% by mass or less. Ash content can be measured according to the method compliant with JIS K6218-2:2005.

[0043] In one embodiment of the present invention, the content of non-recycled carbon black in this rubber composition is preferably 5 to 200 parts by mass, more preferably 20 to 150 parts by mass, even more preferably 25 to 130 parts by mass, and particularly preferably 30 to 110 parts by mass, per 100 parts by mass of (A) rubber component, and may also be 30 to 90 parts by mass, 30 to 80 parts by mass, etc. Furthermore, in one embodiment of the present invention, the content of non-recycled carbon black is, for example, 3 to 60 parts by mass, preferably 5 to 70 parts by mass, more preferably 8 to 60 parts by mass, and even more preferably 10 to 50 parts by mass, per 100 parts by mass of (A) rubber component, or it may be 10 to 30 parts by mass, etc.

[0044] Furthermore, when this rubber composition contains non-recycled carbon black, the mass ratio of recycled carbon black to non-recycled carbon black (recycled CB / non-recycled CB) is preferably 10 / 90 to 90 / 10, more preferably 20 / 80 to 85 / 15, even more preferably 30 / 70 to 80 / 20, and may also be 40 / 60 to 75 / 25, etc. When the above ratio is within the above range, the effects of the present invention tend to be more favorably obtained.

[0045] Furthermore, the total amount of carbon black contained in this rubber composition (total amount of recycled carbon black and non-recycled carbon black) is preferably 100 parts by mass or more, more preferably 110 parts by mass or more, and particularly preferably 120 parts by mass or more, per 100 parts by mass of the rubber component in one example of the embodiment of the present invention. The upper limit is, for example, 200 parts by mass or less, preferably 180 parts by mass or less, and more preferably 150 parts by mass or less. Furthermore, if the rubber composition contains non-recycled carbon black, the total amount of carbon black contained in the rubber composition (total amount of recycled carbon black and non-recycled carbon black) is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and particularly preferably 30 parts by mass or more, per 100 parts by mass of the rubber component in one example of the embodiments of the present invention. The upper limit is, for example, 100 parts by mass or less, preferably 90 parts by mass or less, and more preferably 80 parts by mass or less.

[0046] (Other ingredients) This rubber composition may contain compounding agents commonly used in the rubber industry, such as plasticizers, vulcanizing agents, vulcanization accelerators, vulcanization aids, antioxidants, and fillers (excluding carbon black), to the extent that they do not impair the effects of the present invention. These can be used individually or in combination of two or more.

[0047] [Plasticizer] The plasticizer is not particularly limited, but examples include aromatic oils, ether ester plasticizers, and process oils. These can be used individually or in combination of two or more.

[0048] Examples of aromatic oils include Diana Process AC-12, Diana Process AC-460, Diana Process AH-16 (all manufactured by Idemitsu Showa Shell Co., Ltd.), JSO Aroma 790 (manufactured by Nippon Sun Oil Co., Ltd.), Aromax 1, and Aromax 3 (both manufactured by Fuji Kosan Co., Ltd.). Examples of ether ester plasticizers include plasticizers that have both ether and ester bonds in a single molecule, specifically adipic acid ether ester plasticizers such as bis[2-(2-butoxyethoxy)ethyl] adipate. Examples of process oils include naphthenic oils and paraffinic oils.

[0049] If the rubber composition contains a plasticizer, the amount is not particularly limited, but is, for example, 10 to 120 parts by mass, preferably 20 to 100 parts by mass, and more preferably 30 to 95 parts by mass, per 100 parts by mass of (A) rubber component. It may also be 40 to 90 parts by mass, 50 to 90 parts by mass, etc.

[0050] [Vulcanizing agent] Examples of vulcanizing agents include sulfur-based vulcanizing agents and peroxide-based vulcanizing agents. These can be used individually or in combination of two or more types.

[0051] Examples of sulfur-based vulcanizing agents include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur.

[0052] Examples of peroxide-based vulcanizing agents include 2,4-dichlorobenzoyl peroxide, benzoyl peroxide, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-dibenzoylperoxyhexane, n-butyl-4,4'-di-t-butylperoxyvalerate, dicumyl peroxide, t-butylperoxybenzoate, di-t-butylperoxy-diisopropylbenzene, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexyn-3, and 1,3-bis-(t-butylperoxy-isopropyl)benzene.

[0053] When a sulfur-based vulcanizing agent is used as the vulcanizing agent, its content is preferably 0.4 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and may also be 0.5 to 6 parts by mass, per 100 parts by mass of the rubber component (A).

[0054] Furthermore, when a peroxide-based vulcanizing agent is used as the vulcanizing agent, its content is preferably 0.5 to 30 parts by mass, more preferably 1 to 20 parts by mass, and even more preferably 1.5 to 10 parts by mass, per 100 parts by mass of (A) rubber component.

[0055] [Vulcanization accelerator] The vulcanization accelerator is not particularly limited, but examples include thiram-based vulcanization accelerators such as dibenzothiazole disulfide, tetramethylthiuram disulfide, dipentamethylenethiuram tetrasulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, and tetrabenzylthiuram disulfide; N-oxydiethylene-2-benzothiazolyl sulfenamide, N-cyclohexyl-2-benzothiazolyl sulf Examples include sulfenamide-based vulcanization accelerators such as phenamide, Nt-butyl-2-benzothiazoylsulfenamide, and N,N'-dicyclohexyl-2-benzothiazoylsulfenamide; thiazole-based vulcanization accelerators such as dibenzothiadyl disulfide, 2-mercaptobenzothiazole, 2-mercaptobenzothiazole sodium salt, and 2-mercaptobenzothiazole zinc salt (ZnMBT); dithioate-based vulcanization accelerators such as dibutyldithiocarbamate zinc; and sulfur chloride and sulfur disulfide. These can be used individually or in combination of two or more.

[0056] If the rubber composition contains a vulcanization accelerator, the amount is not particularly limited, but is usually 0.1 to 10 parts by mass, preferably 0.5 to 8 parts by mass, and more preferably 1 to 5 parts by mass, per 100 parts by mass of (A) rubber component.

[0057] [Vulcanization aid] While not particularly limited, examples of vulcanization aids include zinc oxide, zinc oxide (ZnO), stearic acid, and magnesium oxide. These can be used individually or in combination of two or more.

[0058] Examples of zinc oxide include zinc oxide type 1, zinc oxide type 2, zinc oxide type 3, and fine zinc oxide.

[0059] If the rubber composition contains a vulcanization aid, the amount is not particularly limited, but is usually 1 to 25 parts by mass, preferably 2 to 10 parts by mass, per 100 parts by mass of (A) rubber component.

[0060] [Filler] The fillers are not particularly limited, but examples include talc, mica, clay, and calcium carbonate. These can be used individually or in combination of two or more.

[0061] If the rubber composition contains a filler, its content is not particularly limited, but is usually 20 to 180 parts by mass, preferably 50 to 160 parts by mass, and more preferably 60 to 120 parts by mass, per 100 parts by mass of (A) rubber component.

[0062] [Anti-aging agent] Examples of anti-aging agents include carbamate-based anti-aging agents, phenylenediamine-based anti-aging agents, phenol-based anti-aging agents, phenylamine-based anti-aging agents, diphenylamine-based anti-aging agents, quinoline-based anti-aging agents, imidazole-based anti-aging agents, and waxes. These can be used individually or in combination of two or more.

[0063] If the rubber composition contains an anti-aging agent, the amount is not particularly limited, but is usually 0.5 to 10 parts by mass, preferably 0.7 to 8 parts by mass, and more preferably 1 to 6 parts by mass, per 100 parts by mass of (A) rubber component.

[0064] [Preparation of this rubber composition] This rubber composition can be prepared, for example, by appropriately blending rubber components, recycled carbon black, non-recycled carbon black, and the various materials mentioned above as needed, and then kneading them using a kneader, roll, Banbury mixer, or other mixing machine.

[0065] This rubber composition is preferably used as a rubber composition for extruded hoses. The hose made of this rubber composition is not particularly limited in whether it has a single-layer structure or a multi-layer structure with two or more layers laminated together, but it is preferable that at least the innermost layer (or that layer in the case of a single-layer structure) is made of this rubber composition.

[0066] [Hose manufacturing method] The following describes an example of a method for manufacturing a hose made from this rubber composition using an extruder. First, as mentioned above, the rubber component, recycled carbon black, non-recycled carbon black, and various other materials as needed are appropriately blended and mixed using a kneader, roll, Banbury mixer, or other mixing machine to prepare the rubber composition. Referring to Figure 1, a hose made of this rubber composition is manufactured by extruding the rubber composition onto a hollow or mandrel using an extrusion molding machine to form an inner rubber layer 11. Next, a reinforcing yarn layer 12 is formed on the outer surface of the inner rubber layer 11 by spirally braiding reinforcing yarns made of various fibers or plated wires such as brass plated wire. Then, an outer rubber layer 13 is formed by extruding the rubber composition for forming the outer rubber layer onto the outer surface of the reinforcing yarn layer 12. Finally, a three-layer hose can be manufactured by vulcanizing (steam vulcanization, etc.) this laminate under predetermined conditions (for example, 140-170°C for 10-60 minutes).

[0067] In a hose made of the rubber composition obtained as described above, the thickness of the innermost layer (or the single layer in the case of a single-layer structure) is preferably 0.25 to 10 mm, and more preferably 0.5 to 5 mm. Also, when an outer rubber layer 13 is provided as shown in Figure 1, its thickness is preferably 0.25 to 10 mm, and more preferably 0.5 to 5 mm. Furthermore, the inner diameter of the hose is preferably 5 to 60 mm, and more preferably 10 to 40 mm.

[0068] Furthermore, hoses made from this rubber composition can be suitably used as engine cooling system hoses such as radiator hoses used to connect the engine and radiator in vehicles such as automobiles, heater hoses used to connect the engine and heater core, refrigerant transport hoses for coolers, methanol fuel hoses, hydrogen fuel hoses for fuel cell vehicles, and gasoline fuel hoses. In addition, these hoses can be used not only for automobiles but also for other transport machinery (industrial transport vehicles such as airplanes, forklifts, excavators, and cranes, and railway vehicles, etc.).

Example

[0069] Next, the test examples of the present invention will be described. However, the present invention is not limited to these test examples.

[0070] <Test Example> This test example demonstrates that in a rubber composition for an extruded hose using non-reclaimed carbon black and reclaimed carbon black in combination, by using carbon black having a DBP absorption amount within a specific range in combination, excellent effects can be achieved in terms of swell, discharge length, and discharge amount. First, the materials shown below were prepared.

[0071] [(A) Rubber Component] · Rubber Component 1 (EPDM, manufactured by ENEOS MATERIALS, "EP103AF") · Rubber Component 2 (NBR, manufactured by ARLANXEO, Bellprene "3965F")

[0072] [(B) Reclaimed Carbon Black] · Reclaimed CB1 (DBP absorption amount 95 ml / 100 g, ash content 17 mass%, "P365" manufactured by Taiwan Huantuo Technology Co., Ltd.) · Reclaimed CB2 (DBP absorption amount 166 ml / 100 g, ash content 2 mass%, "Synt CB" manufactured by Syntoil)

[0073] [(C) Non-reclaimed Carbon Black] · Non-reclaimed CB1 (DBP absorption amount 43 ml / 100 g, average particle diameter 280 nm, nitrogen adsorption specific surface area 10 m 2 / g, manufactured by Cancarb, "Thermax (registered trademark) 990") · Non-reclaimed CB2 (DBP absorption amount 68 ml / 100 g, average particle diameter 66 nm, nitrogen adsorption specific surface area 27 m 2 / g, iodine adsorption amount 26 g / kg, manufactured by Tokai Carbon Co., Ltd., "Seast (registered trademark) S") · Non-reclaimed CB3 (DBP absorption amount 113 ml / 100 g, average particle diameter 19 nm, nitrogen adsorption specific surface area 250 m 2( / g, iodine adsorption capacity 139g / kg, manufactured by Tokai Carbon Co., Ltd., "Seast (registered trademark) 9M") • Non-regenerated CB4 (DBP absorption rate 115 ml / 100 g, nitrogen adsorption specific surface area 108 m²) 2 ( / g, iodine adsorption capacity 119g / kg, manufactured by Cabot Japan, "VULCAN(registered trademark) 6J") • Non-regenerated CB5 (DBP absorption rate 119 ml / 100 g, nitrogen adsorption specific surface area 90 m²) 2 ( / g, iodine adsorption capacity 92g / kg, manufactured by Cabot Japan, "VULCAN(registered trademark) 3D") • Non-regenerated CB6 (DBP absorption rate 129 ml / 100 g, nitrogen adsorption specific surface area 46 m²) 2 ( / g, iodine adsorption capacity 52g / kg, manufactured by Cabot Japan, "SPHERON(registered trademark) 1420G") • Non-regenerated CB7 (DBP absorption rate 158 ml / 100 g, average particle size 38 nm, nitrogen adsorption specific surface area 56 m²) 2 ( / g, iodine adsorption capacity 62g / kg, manufactured by Tokai Carbon Co., Ltd. "Seasto (registered trademark) G116HM")

[0074] [Test Example 1-1] The above various materials are blended at the ratios shown in Table 1 below. Further, 1.0 part by mass of a vulcanizing agent (“SULFAX (registered trademark) T-10” manufactured by Tsurumi Chemical Industry Co., Ltd.), 0.5 part by mass of vulcanization accelerator 1 (“Sunceler (registered trademark) TT-G” manufactured by Sanshin Chemical Industry Co., Ltd.), 0.5 part by mass of vulcanization accelerator 2 (“Sunceler (registered trademark) TET-G” manufactured by the same company), 1.0 part by mass of vulcanization accelerator 3 (“Sunceler (registered trademark) CZ-G” manufactured by the same company), 1.0 part by mass of vulcanization accelerator 4 (“Nocceler (registered trademark) DM-P” manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), 1.0 part by mass of vulcanization accelerator 5 (“Nocceler (registered trademark) TRA” manufactured by the same company), 5 parts by mass of vulcanization aid 1 (“Zinc Oxide Type 2” manufactured by Mitsui Mining & Smelting Co., Ltd.), 1 part by mass of vulcanization aid 2 (“Bead Stearic Acid Sakura” manufactured by Nippon Oil & Fats Co., Ltd.), and 70 parts by mass of calcium carbonate (“Whiton (registered trademark) SB” manufactured by Shiraishi Calcium Co., Ltd.) are blended (the above are the contents relative to 100 parts by mass of the rubber component (EPDM), and these are collectively referred to as “additional components”). These are kneaded using a Banbury mixer and an open roll to prepare a rubber composition for an extruded hose.

[0075] [Test Example 1-2] The above various materials are blended at the ratios shown in Table 2. Further, the additional components are blended in the same manner as above. These are kneaded using a Banbury mixer and an open roll to prepare a rubber composition for an extruded hose.

[0076] [Test Example 1-3] The above various materials are blended at the ratios shown in Table 3. Further, 0.5 part by mass of a vulcanizing agent (“Sunmix (registered trademark) S-80NBR” manufactured by Sanshin Chemical Industry Co., Ltd.), 2.5 parts by mass of a vulcanizing agent (“Sunmix (registered trademark) CZ-80NBR” manufactured by the same company), 2.0 parts by mass of vulcanization accelerator 1 (“Sunceler (registered trademark) TT-PTC” manufactured by the same company), 4 parts by mass of vulcanization aid 1 (“Zinc Oxide Type 2” manufactured by Mitsui Mining & Smelting Co., Ltd.), 1 part by mass of vulcanization aid 2 (“Bead Stearic Acid Sakura” manufactured by Nippon Oil & Fats Co., Ltd.), 2 parts by mass of an anti-aging agent (3C), and 2 parts by mass of an anti-aging agent (TMQ) are blended (the above are the contents relative to 100 parts by mass of the rubber component (NBR)). These are kneaded using a Banbury mixer and an open roll to prepare a rubber composition for an extruded hose.

[0077] The rubber composition for extruded hoses obtained in this manner was used for the following evaluations. The results are shown in Tables 1-3.

[0078] A rubber composition for extruded hoses was extruded into a hose shape under the following conditions, and the wall thickness, outer diameter swell (times), discharge length (mm / 20sec.), and discharge volume (g / 20sec.) were measured. The results are shown in Tables 1 to 3. Swell was calculated by leaving the extruded tube undisturbed in an RT environment for 24 hours and measuring its outer diameter and wall thickness. Discharge length and discharge volume were measured by the mass and length during continuous discharge for 20 seconds. The swell, discharge length, and discharge volume shown in each table are converted values ​​with the measured values ​​from Test Example 1-1a, Test Example 1-2a, or Test Example 1-3a set to 100. [Extrusion conditions] • Extruder (φ20, L / D=16, manufactured by Mitsuba Seisakusho Co., Ltd.) • Fixture settings: Die 10φ, spindle 7φ • Rotation speed: 40 rpm Temperature settings: Head 100℃, Cylinder head 80℃, Die 89~90℃ (Discharge rubber temperature 90~92℃)

[0079] [Table 1]

[0080] [Table 2]

[0081] [Table 3]

[0082] [Test Example 1-1] (Swell (thick)) As shown in Table 1, when comparing the case where non-recycled carbon black is used alone (Test Example 1-1a) with the case where recycled carbon black is used alone (Test Example 1-1b), it was confirmed that the swell (wall thickness) was the same. However, when non-recycled and recycled carbon black were used in combination (Test Examples 1-1c to 1-1i), it became clear that the swell (wall thickness) worsened compared to when either non-recycled or recycled carbon black was used alone.

[0083] Furthermore, as shown in Test Example 1-1c, when a non-regenerating CB with low DBP absorption (DBP absorption: 43 ml / 100 g) was used in combination, it was confirmed that the swell (wall thickness) worsened from "100" to "136". On the other hand, as in the case of test examples 1-1d to 1-1i, when non-regenerated CBs with DBP absorption rates of 68 to 158 ml / 100g are used in combination, it was confirmed that swell can be suppressed to "118" or "109", effectively suppressing the deterioration of swell (wall thickness).

[0084] Based on the above, it was confirmed that a rubber composition for extruded hoses containing (A) a rubber component, (B) recycled carbon black with a DBP absorption rate of 70-170 ml / 100g, and (C) non-recycled carbon black with a DBP absorption rate of 50-160 ml / 100g can suppress the deterioration of swell (wall thickness) caused by the combined use of components (B) and (C).

[0085] (Swell (outer diameter)) Similar results were observed for swell (outer diameter). Specifically, as shown in Table 1, when comparing the case where non-recycled CB is used alone as carbon black (Test Example 1-1a) and the case where recycled CB is used alone (Test Example 1-1b), the swell (outer diameter) was found to be the same. However, when non-recycled CB and recycled CB were used in combination as carbon black (Test Examples 1-1c to 1-1i), it became clear that the swell (outer diameter) worsened compared to when either non-recycled CB or recycled CB was used alone.

[0086] Furthermore, as shown in Test Example 1-1c, when a non-regenerating CB with low DBP absorption (DBP absorption: 43 ml / 100 g) was used in combination, it was confirmed that the swell (outer diameter) worsened from "100" to "118". On the other hand, as in the case of test examples 1-1d to 1-1i, when non-regenerating CBs with a DBP absorption rate of 68 to 158 ml / 100g are used in combination, the swell (outer diameter) value can be suppressed to "109", confirming that the deterioration of swell (outer diameter) can be effectively suppressed.

[0087] (discharge length) Furthermore, as shown in Table 1, when using non-regenerated CBs with a DBP absorption rate of 68-158 ml / 100g as the non-regenerated CB used in combination, a significant effect on the dispensing length was confirmed. In other words, as shown in the results in Table 1, when non-regenerated CB and regenerated CB were used in combination as carbon black (Test Examples 1-1c to 1-1i), a tendency for the discharge length to worsen was observed compared to when non-regenerated CB was used alone as carbon black (Test Example 1-1a). Furthermore, as in Test Example 1-1c, when using a non-regenerated CB with low DBP absorption (DBP absorption: 43 ml / 100 g), it was confirmed that the dispensing length was reduced to 42% compared to Test Example 1-1a, which used a non-regenerated CB alone. On the other hand, as in the case of test examples 1-1d to 1-1i, when non-regenerating CBs with a DBP absorption rate of 68 to 158 ml / 100g are used in combination, the dispensing length is 52 to 77%, confirming that the deterioration of the dispensing length can be effectively suppressed.

[0088] (Discharge amount) Furthermore, as shown in Table 1, when using non-regenerated CBs with a DBP absorption rate of 68-158 ml / 100g as the non-regenerated CB used in combination, a significant effect on the discharge volume was confirmed. In other words, as shown in the results in Table 1, when non-recycled CB and recycled CB were used in combination as carbon black (Test Examples 1-1c to 1-1i), a tendency for the discharge volume to worsen was observed compared to when non-recycled CB was used alone (Test Example 1-1a). Furthermore, as in Test Example 1-1c, when using non-regenerated CB with low DBP absorption (DBP absorption: 43 ml / 100 g), it was confirmed that the discharge volume was reduced to 60% compared to Test Example 1-1a, which used non-regenerated CB alone. On the other hand, as in the case of Test Examples 1-1d to 1-1i, when non-regenerated CBs with a DBP absorption rate of 68 to 158 ml / 100g are used in combination, the discharge volume is 66 to 90%, confirming that the deterioration of the discharge volume can be effectively suppressed.

[0089] [Test Example 1-2] Test Example 1-2, shown in Table 2, is a test example in which the type of regenerated CB used in Test Example 1-1 was changed. As shown in the results in Table 2, the same results as in Test Example 1-1 were obtained.

[0090] [Test Examples 1-3] Test Examples 1-3, shown in Table 3, are test examples in which the rubber component used in Test Example 1-1 was changed to NBR. As shown in the results in Table 3, the same results as in Test Example 1-1 were obtained.

[0091] Based on the above, it was confirmed that a rubber composition for extruded hoses containing (A) a rubber component, (B) recycled carbon black with a DBP absorption rate of 70-170 ml / 100g, and (C) non-recycled carbon black with a DBP absorption rate of 50-160 ml / 100g can suppress the deterioration of swell (wall thickness, outer diameter) caused by the combined use of components (B) and (C), and can also suppress the deterioration of extrusion length and extrusion volume, thus demonstrating a significant effect in improving the balance of these properties. [Industrial applicability]

[0092] The rubber composition for extruded hoses of the present invention can be suitably used as hoses for automobiles, such as radiator hoses used to connect the engine and radiator in vehicles such as automobiles, heater hoses used to connect the engine and heater core, refrigerant transport hoses for coolers, methanol fuel hoses, hydrogen fuel hoses for fuel cell vehicles, and gasoline fuel hoses. Furthermore, these hoses can be used not only for automobiles but also for other transport machinery (industrial transport vehicles such as airplanes, forklifts, excavators, and cranes, and railway vehicles). [Explanation of Symbols]

[0093] 11. Inner rubber layer 12 Reinforcement thread layer 13. Outer rubber layer

Claims

1. A rubber composition for extruded hoses, comprising the following components (A) to (C), wherein the content of component (B) is 20 to 180 parts by mass and the content of component (C) is 15 to 150 parts by mass per 100 parts by mass of rubber component (A). (A) Rubber component (B) Recycled carbon black with DBP absorption of 70-170 ml / 100g (C) Non-recycled carbon black with DBP absorption of 50-160 ml / 100g and nitrogen adsorption specific surface area of ​​56-250 m² / g

2. The rubber composition for extruded hoses according to claim 1, wherein component (C) is non-recycled carbon black with a DBP absorption amount of 80 to 160 ml / 100 g.

3. The rubber composition for extruded hoses according to claim 1 or 2, wherein the mass ratio (B / C) of component (B) to component (C) is 10 / 90 to 90 / 10.

4. The rubber composition for extruded hoses according to claim 1 or 2, wherein the total amount of carbon black contained in the above extruded hose rubber composition (total amount of component (B) and component (C)) is 100 parts by mass or more per 100 parts by mass of component (A).

5. A hose made of the rubber composition for extruded hoses according to claim 1 or 2.

6. A method for manufacturing an extruded hose, comprising the step of extruding a rubber composition for extruded hoses obtained by kneading the following components (A) to (C), wherein swell in the above step is suppressed, wherein the content of component (B) in the extruded hose rubber composition is 20 to 180 parts by mass and the content of component (C) is 15 to 150 parts by mass per 100 parts by mass of rubber component (A). (A) Rubber component (B) Recycled carbon black with DBP absorption of 70-170 ml / 100g (C) Non-recycled carbon black with DBP absorption of 50-160 ml / 100g and nitrogen adsorption specific surface area of ​​56-250 m² / g

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