JP2016030793A - Rubber composition for hose and hose - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a hose having excellent processability and thermal aging resistance after vulcanization.SOLUTION: There is provided a rubber composition for a hose which comprises a diene-based rubber containing an ethylene-propylene-diene rubber, carbon black, an organic peroxide and a fatty acid metal salt, wherein the content of the ethylene-propylene-diene rubber in the diene-based rubber is 90 mass% or more, the content of the carbon black is 75 to 115 pts.mass based on 100 pts.mass of the diene-based rubber, the content of the organic peroxide is 1 to 5 pts.mass based on 100 pts.mass of the diene-based rubber and the content of the fatty acid metal salt is 1 to 5 pts.mass based on 100 pts.mass of the diene-based rubber.SELECTED DRAWING: None

Description

  The present invention relates to a rubber composition for a hose and a hose.

Conventionally, the rubber composition for hoses used for the rubber layer of a hose is known (for example, refer patent document 1).
Specific examples of hoses include hydraulic hoses (power steering hoses) used in power steering circuits for the purpose of transmitting hydraulic pressure and reducing hydraulic pump drive noise, refrigerant transport hoses used in car air conditioners, etc., oil such as crude oil Marine hose that transports

JP 2006-307987 A

The inventor tried to improve physical properties of a conventional rubber composition for a hose.
Specifically, for the rubber composition for hoses, a large amount of ethylene-propylene-diene rubber (hereinafter also referred to as “EPDM”) in the diene rubber is blended, and an organic peroxide is used as a vulcanizing agent. Therefore, we tried to improve the heat aging resistance after vulcanization. Heat aging resistance is particularly required in the cover rubber layer of the hose. In addition, by increasing the content of carbon black, attempts were made to improve normal physical properties (eg, tensile strength) after vulcanization.

As a result, for such a rubber composition for hose, the normal physical properties after vulcanization are relatively good, but the processability is inferior and the heat aging resistance after vulcanization is also insufficient. It became clear.
Then, when this inventor mix | blended fatty acid ester, although the improvement effect of workability was seen, the heat aging resistance after vulcanization was still inadequate.

  This invention is made | formed in view of the above point, and it aims at providing the rubber composition for hoses which is excellent in workability and the heat aging resistance after a vulcanization | cure.

  As a result of intensive investigations to achieve the above object, the present inventors have improved the workability of the rubber composition for hoses and the heat aging resistance after vulcanization by blending a specific amount of fatty acid metal salt. The present invention has been completed.

That is, the present invention provides the following (1) to (4).
(1) A diene rubber containing ethylene-propylene-diene rubber, carbon black, an organic peroxide, and a fatty acid metal salt, and the content of the ethylene-propylene-diene rubber in the diene rubber is 90. The carbon black content is 75 to 115 parts by mass with respect to 100 parts by mass of the diene rubber, and the organic peroxide content is 100 parts by mass of the diene rubber. The rubber composition for hoses which is 1-5 mass parts with respect to 100 mass parts of said diene rubbers, and is 1-5 mass parts.
(2) The rubber composition for hoses according to (1) above, wherein the ethylene-propylene-diene rubber has a Mooney viscosity at 100 ° C. of 41 or more.
(3) DBP absorption amount of the carbon black is 90~130cm ³ / 100g, an iodine adsorption amount of the carbon black is 30 to 50 mg / g, rubber hose according to (1) or (2) Composition.
(4) A hose having a rubber layer formed using the rubber composition for a hose according to any one of (1) to (3).

  ADVANTAGE OF THE INVENTION According to this invention, the rubber composition for hoses which is excellent in workability and heat aging resistance after vulcanization can be provided.

It is a perspective view which shows an example of the hose of this invention.

Below, the rubber composition for hoses of this invention and the hose of this invention are demonstrated.
In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Rubber composition for hose]
The rubber composition for hose of the present invention (hereinafter also referred to as a unit “the rubber composition of the present invention”) includes a diene rubber containing ethylene-propylene-diene rubber, carbon black, an organic peroxide, and a fatty acid metal salt. The ethylene-propylene-diene rubber content in the diene rubber is 90% by mass or more, and the carbon black content is 75-115 mass with respect to 100 parts by mass of the diene rubber. And the content of the organic peroxide is 1 to 5 parts by mass with respect to 100 parts by mass of the diene rubber, and the content of the fatty acid metal salt with respect to 100 parts by mass of the diene rubber. 1 to 5 parts by mass of a rubber composition for hoses.
Hereinafter, each component contained in the rubber composition of the present invention will be described in detail.

[Diene rubber]
The diene rubber contained in the rubber composition of the present invention includes ethylene-propylene-diene rubber (EPDM).
In the present invention, the content of the EPDM in the diene rubber is 90% by mass or more, preferably 95% by mass or more, from the viewpoint of improving the heat aging resistance after vulcanization of the rubber composition for hoses. 100 mass% is more preferable.

  The rubber component other than EPDM is not particularly limited. For example, isoprene rubber (IR), butadiene rubber (BR), aromatic vinyl-conjugated diene copolymer rubber (for example, styrene butadiene rubber (SBR)), acrylonitrile- Examples thereof include butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and chloroprene rubber (CR).

<EPDM>
Ethylene-propylene-diene rubber (EPDM) introduces a small amount of diene component as a third component into ethylene-propylene rubber (EPM), which is a copolymer of ethylene and propylene, and has a double bond in the main chain. It is
Representative diene components include, for example, ethylidene norbornene (ENB), 1,4-hexadiene (1,4-HD), dicyclopentadiene (DCP), and among them, ENB is preferable.
Further, the content of the diene component in EPDM is preferably 7 to 11% by mass.

The Mooney viscosity at 100 ° C. of the above EPDM is preferably 41 or more, more preferably 60 or more, and even more preferably 70 or more, from the viewpoint of improving the normal properties after vulcanization of the rubber composition for hoses. On the other hand, the upper limit value of Mooney viscosity is not particularly limited, and examples include 120 or less.
The Mooney viscosity is a viscosity measured according to JIS K6300-1-2013 using an L-shaped rotor under conditions of a preheating time of 1 minute, a rotor rotation time of 4 minutes, and a test temperature of 100 ° C. (ML1 + 4, 100 ° C).

〔Carbon black〕
The rubber composition of the present invention contains carbon black. From the viewpoint of improving the heat aging resistance after vulcanization of the rubber composition for hoses, the content of the carbon black is relatively reduced to the amount of rubber that is likely to be heat-aged. On the other hand, it is 75 to 115 parts by mass, preferably 90 to 115 parts by mass, more preferably more than 90 parts by mass and 115 parts by mass or less, and further preferably 93 to 115 parts by mass.

DBP oil absorption amount of the carbon black from the viewpoint of the reinforcing property of the rubber is preferably ^{90~130cm 3 / 100g, 95~120cm 3 /} 100g and more preferably.
Here, the DBP oil absorption amount (absorption amount) is a measure of the ability of carbon black to absorb liquid (DBP), and the larger this value, the larger the structure of carbon black.
The DBP oil absorption is measured according to JIS K 6217-4: 2008 “Carbon black for rubber—Basic characteristics—Part 4: Determination of oil absorption”.

The iodine adsorption amount of the carbon black is preferably 30 to 50 mg / g, more preferably 35 to 45 mg / g, from the viewpoint of rubber reinforcement.
The iodine adsorption amount is measured according to JIS K 62177-1: 2008 “Carbon black for rubber—Basic characteristics—Part 1: Determination of iodine adsorption amount (titration method)”.

Further, the nitrogen adsorption specific surface area of the carbon black is not particularly limited, but is preferably ^{30~50m 2 / g, 35~45m 2 /} g is more preferable.
Here, the nitrogen adsorption specific surface area refers to a specific surface area obtained by a nitrogen adsorption method, and usually, the smaller this value, the larger the particle size of the carbon black.
The nitrogen adsorption specific surface area is measured according to JIS K 6217-2: 2001 “carbon black for rubber—basic characteristics—part 2: determination of specific surface area—nitrogen adsorption method—single point method”.

[Organic peroxide]
The rubber composition of the present invention contains an organic peroxide as a vulcanizing agent from the viewpoint of improving the heat aging resistance after vulcanization.
In general, the intermolecular crosslinking of unsaturated bonds such as sulfur is called vulcanization, but in the present invention, crosslinking by a vulcanizing agent (crosslinking agent) such as an organic peroxide other than sulfur is also added. Called sulfur.
The organic peroxide is not particularly limited, and conventionally known ones can be used. Specific examples thereof include dicumyl peroxide, di-t-butyl peroxide, 1,3-bis (t-butyl peroxide). Oxyisopropyl) benzene, 4,4′-di (t-butylperoxy) valeric acid n-butyl, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, and the like. 1 type may be used independently and 2 or more types may be used together.
Content of the said organic peroxide is 1-5 mass parts with respect to 100 mass parts of said diene rubbers, and 1-3 mass parts is preferable.

[Fatty acid metal salt]
The rubber composition of the present invention is excellent in processability and heat aging resistance after vulcanization by containing a fatty acid metal salt, which is a fatty acid metal salt.
Such an effect is a surprising effect that cannot be obtained when using only a fatty acid (eg, stearic acid) or a fatty acid ester (eg, methyl stearate).

  12-26 are preferable and, as for carbon number of the fatty acid which comprises the said fatty acid metal salt, 16-22 are more preferable. Moreover, as said fatty acid, a linear or branched saturated or unsaturated fatty acid is mentioned.

  Specific examples of saturated fatty acids include hexanoic acid (caproic acid; carbon number 6), octanoic acid (caprylic acid; carbon number 8), decanoic acid (capric acid; carbon number 10), dodecanoic acid (lauric acid; carbon number 12). ), Tetradecanoic acid (myristic acid; carbon number 14), hexadecanoic acid (palmitic acid; carbon number 16), heptadecanoic acid (margaric acid; carbon number 17), octadecanoic acid (stearic acid; carbon number 18), eicosanoic acid (arachidin) Examples include acid; carbon number 20), docosanoic acid (behenic acid; carbon number 22), tetracosanoic acid (lignoceric acid; carbon number 24), hexacosanoic acid (serotinic acid; carbon number 26), and the like.

  Specific examples of the unsaturated fatty acid include myristoleic acid (carbon number 14), 9-hexadecenoic acid (palmitoleic acid; carbon number 16), cis-9-octadecenoic acid (oleic acid; carbon number 18), elaidic acid (carbon 18), 11-octadecenoic acid (vaccenic acid; carbon number 18), cis, cis-9,12-octadecadienoic acid (linoleic acid; carbon number 18), 9,12,15-octadecatrienoic acid (( 9,12,15) -linolenic acid; carbon number 18), 6,9,12-octadecatrienoic acid ((6,9,12) -linolenic acid; carbon number 18), pinolenic acid (carbon number 18), 9,11,13-octadecatrienoic acid (eleostearic acid; carbon number 18), gadoleic acid (carbon number 20), eicosenoic acid (carbon number 20), eicosadienoic acid (carbon number 20), , 11-icosadienoic acid (carbon number 20), 5,8,11-icosatrienoic acid (carbon number 20), 5,8,11,14-icosatetraenoic acid (arachidonic acid; carbon number 20), erucic acid (carbon number 22) ), Docosadienoic acid (carbon number 22), cis-15-tetradocosanoic acid (nervonic acid (carbon number 24)), and the like.

  Examples of the metal element that forms a salt with the fatty acid include group 1 elements (alkali metals), group 2 elements (alkaline earth metals), group 3 elements, zinc, and aluminum in the periodic table. Of these, zinc is preferred.

  A commercial item can be used as said fatty acid metal salt, for example, C14-C18 unsaturated fatty acid zinc salt (STRUKTOL A50P, the product made by STRUKTOL) is mentioned suitably.

The said fatty acid metal salt may be used individually by 1 type, and may use 2 or more types together.
Content of the said fatty acid metal salt is 1-5 mass parts with respect to 100 mass parts of said diene rubbers, and 1-4 mass parts is preferable.

[Optional ingredients]
The rubber composition of the present invention can contain various additives such as a filler, a plasticizer, an anti-aging agent, a softening agent, a crosslinking aid, an adhesion aid, and a processing aid as necessary.
Specific examples of the filler include calcium carbonate, barium sulfate, talc, clay, titanium oxide, and silica.
Specific examples of the plasticizer include synthetic plasticizers such as phthalate ester, diallyl phthalate, adipic acid ester, fatty acid ester, trimellitic acid ester; liquid rubber; and the like.
The anti-aging agent is not particularly limited as long as it is a heat-resistant anti-aging agent, a weather-resistant anti-aging agent and the like which are usually used in rubber compositions. Specific examples thereof include N- (1,3-dimethylbutyl). ) -N'-phenyl-p-phenylenediamine (6PPD), N, N'-dinaphthyl-p-phenylenediamine (DNPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), styrenated phenol (SP) etc. are mentioned.
Specific examples of the softener include paraffin oil (process oil) and vegetable oil.
Specific examples of the crosslinking aid include triallyl isocyanurate (TAIC, manufactured by Nippon Kasei Co., Ltd.).
Specific examples of the adhesion assistant include 2,4,6-trimercapto-1,3,5-triazine.

[Method for producing rubber composition for hose]
The method for producing the rubber composition of the present invention is not particularly limited, and specific examples thereof include, for example, each component described above using a known method and apparatus (for example, a Banbury mixer, a kneader, a roll, etc.) Examples thereof include a kneading method.
The rubber composition of the present invention can be vulcanized under conventionally known vulcanization conditions.

[hose]
The hose of the present invention is a hose having a rubber layer formed using the rubber composition for a hose of the present invention.
Since the hose of the present invention has a rubber layer formed using the rubber composition of the present invention, it is excellent in heat aging resistance as described above.
Examples of the hose that can use the rubber composition for a hose of the present invention include a hydraulic hose (power steering hose), a refrigerant transport hose, a marine hose, and the like.

Here, an example of the suitable embodiment of the hose of this invention is demonstrated using FIG. FIG. 1 is a perspective view of each hose layer cut away.
As shown in FIG. 1, the hose 1 has an inner rubber layer 2 as an inner tube, and has a reinforcing layer 3 and a cover rubber layer 4 as an outer tube on the upper layer.
Next, the rubber layer (inner rubber layer, cover rubber layer) and the reinforcing layer constituting the hose of the present invention will be described in detail.

[Rubber layer]
The rubber layer is a layer formed using the rubber composition of the present invention. When the rubber layer has an inner rubber layer and a cover rubber layer, at least one of the rubber layers is formed using the rubber composition of the present invention. To form.
The inner rubber layer preferably has a thickness of 0.2 to 4.0 mm, and more preferably 0.4 to 2.5 mm.
Similarly, the thickness of the cover rubber layer is preferably 0.2 to 4.0 mm, and more preferably 0.4 to 2.5 mm.

(Reinforcement layer)
The reinforcing layer is a layer provided on the outside of the rubber layer (inner rubber layer in the case of having an inner rubber layer and a cover rubber layer) from the viewpoint of maintaining strength.
In the present invention, the reinforcing layer may be formed in a blade shape or a spiral shape.
Moreover, the material which forms the said reinforcement layer is not specifically limited, A conventionally well-known metal wire and various fiber materials (nylon, polyester, etc.) can be used.

[Other rubber layers, resin layers]
The hose of the present invention may have another rubber layer or a resin layer between the rubber layer and the reinforcing layer.
The rubber material forming the other rubber layer is not particularly limited, and for example, rubber used for the production of the rubber composition of the present invention can be used.
Moreover, the resin material which forms the said resin layer is not specifically limited, For example, a conventionally well-known polyamide resin, a polyester resin, etc. can be used.

[Method of manufacturing hose]
The method for producing the hose of the present invention having the rubber layer and the reinforcing layer is not particularly limited, and a conventionally known method can be used.
Specifically, on the mandrel, the rubber layer (inner rubber layer if the inner rubber layer and the cover rubber layer are provided), the reinforcing layer and the rubber layer (cover rubber if the inner rubber layer and the cover rubber layer are provided) Layer) in this order, and then press vulcanization, steam vulcanization, oven vulcanization (hot air vulcanization) or hot water vulcanization under conditions of 140 to 190 ° C. and 30 to 180 minutes. For example, a method of producing by vulcanization and bonding is preferably exemplified.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

[Preparation of rubber composition for hose]
The components shown in Table 1 below were blended in the proportions (parts by mass) shown in Table 1 below to prepare a rubber composition for hoses. Specifically, among the components shown in Table 1 below, the components excluding organic peroxides were kneaded for 5 minutes with a Banbury mixer (3.4 liters) and released when the temperature reached 170 ° C. Got. Next, an organic peroxide was kneaded with the obtained master batch with an open roll to obtain a rubber composition for a hose.

[Machinability]
The minimum Mooney viscosity of each obtained rubber composition for hose was measured. The minimum Mooney viscosity means a value (Vm) measured at 125 ° C. in the Mooney scorch test of JIS K 6300-1: 2013.
Further, a round bar-shaped head was assembled in a small screw type extruder (a screw used a compression type), and the extrusion performance was confirmed at a head and cylinder temperature of 80 ° C. and a rotation speed of 60 rpm. And the thing in the shape which can be used as a hose, such as an external appearance, was shown as "(circle)", and the thing in the unusable level was shown as "x".
If the minimum Mooney viscosity is 70 or less and the extrudability is “◯”, it can be evaluated as having excellent workability. The results are shown in Table 1 below.

[Normal physical properties]
The obtained rubber composition for hoses was vulcanized for 45 minutes under a pressure of 3.0 MPa using a press molding machine at 150 ° C. to prepare a vulcanized sheet having a thickness of 2 mm. A JIS No. 3 dumbbell-shaped test piece was punched from this sheet, and a tensile test at a tensile speed of 500 mm / min was conducted in accordance with JIS K6251: 2010. Tensile strength (T _B ) [MPa] and elongation at break (E _B ) [%] Was measured at room temperature.
Further, according to JIS K6253-3: 2012 type A durometer, the hardness (H _S ) of the vulcanized sheet at room temperature was measured.
The results are shown in Table 1 below.

[Heat aging resistance]
The vulcanized sheet was subjected to an aging test at 150 ° C. × 72 hours or 150 ° C. × 168 hours, and the elongation at break was measured in the same manner as described above (in the following Table 1, “E _B (150 ° C. × 72 h) ”and“ E _B (150 ° C. × 168 h) ”).
Further, during cutting when the rate of change of elongation was determined [%] (the following Table 1 before and after the aging test, referred to as "ΔE _B (150 ℃ × 72h)" and "ΔE _B (150 ℃ × 168h)" ).
If ΔE _B (150 ° C. × 72 h) exceeds −21% and ΔE _B (150 ° C. × 168 h) exceeds −55%, it can be evaluated as having excellent heat aging resistance. The results are shown in Table 1 below.

Details of each component shown in Table 1 are as follows.
EPDM: Mitsui EPT4070 (diene component: ENB, diene content: 8.1 mass%, Mooney viscosity at 100 ° C .: 89, manufactured by Mitsui Chemicals, Inc.)
Carbon black: HTC # 100 (DBP absorption amount: 105cm ³ / 100g, iodine adsorption: 42mg / g, manufactured by Nippon Carbon Co., Ltd.)
・ Zinc oxide: Zinc Hana 3 (manufactured by Shodo Chemical Industry Co., Ltd.)
・ Crosslinking aid: triallyl isocyanurate (TAIC, Nippon Kasei Co., Ltd.)
・ Fatty acid metal salt: STRUKTOL A50P (manufactured by STRUKTOL)
-Fatty acid ester 1: Methyl stearate-Fatty acid ester 2: Sorbitan tristearate-Paraffin oil: Process oil 123 (made by Showa Shell Sekiyu KK)
Organic peroxide: 1,3-bis (t-butylperoxyisopropyl) benzene (Perkadox 14/40 (40% by mass), manufactured by Kayaku Akzo)

As is clear from the results shown in Table 1, the rubber compositions for hoses of Examples 1 to 4 containing a fatty acid metal salt were excellent in processability and heat aging resistance after vulcanization.
In comparison with Example 3 and Example 4, Example 3 having a higher carbon black content was more excellent in heat aging resistance after vulcanization.
On the other hand, the rubber composition for hoses of Comparative Example 1 containing no fatty acid metal salt was inferior in processability and heat aging resistance after vulcanization.
Moreover, the rubber composition for hoses of Comparative Examples 2 to 5 containing fatty acid ester 1 or fatty acid ester 2 instead of the fatty acid metal salt was inferior in heat aging resistance after vulcanization.
Moreover, although the fatty acid metal salt was contained, the comparative example 6 in which the content of carbon black was too low was inferior in heat aging resistance after vulcanization.

1: Hose 2: Inner rubber layer 3: Reinforcement layer 4: Cover rubber layer

Claims (4)

Containing a diene rubber including ethylene-propylene-diene rubber, carbon black, an organic peroxide, and a fatty acid metal salt;
The ethylene-propylene-diene rubber content in the diene rubber is 90% by mass or more,
The carbon black content is 75 to 115 parts by mass with respect to 100 parts by mass of the diene rubber,
The content of the organic peroxide is 1 to 5 parts by mass with respect to 100 parts by mass of the diene rubber,
The rubber composition for hoses whose content of the said fatty-acid metal salt is 1-5 mass parts with respect to 100 mass parts of said diene rubbers.   The rubber composition for hoses according to claim 1, wherein the ethylene-propylene-diene rubber has a Mooney viscosity at 100 ° C of 41 or more. Wherein a DBP absorption of carbon black is 90~130cm ³ / 100g, an iodine adsorption amount of the carbon black is 30 to 50 mg / g, rubber composition for a hose as claimed in claim 1 or 2.   The hose which has a rubber layer formed using the rubber composition for hoses of any one of Claims 1-3.