JP2020152863A - Rubber composition and cross-linked body thereof - Google Patents

Abstract

To provide a rubber composition having excellent oil resistance while maintaining the other characteristics of an ethylene α-olefin non-conjugated polyene copolymer such as EPDM; and to provide a rubber cross-linked body.SOLUTION: The rubber composition includes 100 pts.mass of an ethylene 3-20C α-olefin non-conjugated polyene copolymer (A) and 3 to 40 pts.mass of an ethylene vinyl acetate copolymer (B). Preferably, the content of vinyl acetate in the ethylene vinyl acetate copolymer (B) is 5 to 50 pts.mass.SELECTED DRAWING: None

Description

The present invention relates to a rubber composition and a crosslinked product thereof.

Ethylene propylene / diene copolymer rubber (EPDM) has excellent heat aging resistance, weather resistance, and ozone resistance compared to general-purpose conjugated diene rubber because it does not have an unsaturated bond in the main chain of its molecular structure. It is widely used in various applications such as parts for electric wires, materials for electric wires, electrical / electronic parts, building civil engineering materials, and industrial material parts.

EPDM is often used in the form of a rubber composition containing a reinforcing material such as carbon black, and is used for producing a rubber crosslinked product. The rubber composition containing EPDM and the like is subjected to molding and cross-linking in a form further containing a cross-linking agent, and is guided to a rubber cross-linked body.

By the way, the rubber composition containing EPDM and the rubber crosslinked product may be required to have oil resistance when used in an environment where they may be exposed to oil, particularly when used for automobile applications. However, EPDM has a structure composed of hydrocarbons and is non-polar, so that it tends to have poor oil resistance as compared with polar rubber and the like. Therefore, rubber compositions and rubber crosslinked products containing EPDM need to have improved oil resistance when used in an environment where they may be exposed to oil. Under such circumstances, various attempts have been conventionally made to improve the oil resistance of the rubber composition containing EPDM or the crosslinked rubber.

There are various methods for improving the oil resistance of the rubber composition containing EPDM or the crosslinked rubber.
For example, increasing the oil content in the rubber composition containing EPDM reduces the amount of oil absorbed from the outside of the rubber crosslinked product to some extent when the obtained rubber crosslinked product is exposed to oil. be able to.

Attempts have also been made to blend polar rubber with a rubber composition containing EPDM. For example, Patent Document 1 discloses a rubber composition containing a blend material obtained by blending EPDM and nitrile rubber having excellent oil resistance in a specific ratio as a rubber composition used as a raw material for a hose. Patent Document 1 also shows an evaluation of oil resistance of a crosslinked product obtained by vulcanizing a rubber composition.

Attempts have also been made to add fillers to EPDM. For example, Patent Document 2 discloses, as an oil-resistant hose, a hose formed by molding a mixture of EPDM and a filler, and when the amount of the filler with respect to EPDM is a specific ratio, the oil resistance is improved. It has been shown to improve. In relation to this, Patent Document 3 describes an EPDM rubber composition in which, as an EPDM rubber composition having excellent oil resistance, a blend of a plurality of specific types of fillers in a specific ratio is adopted as the filler. Is disclosed. Here, Patent Document 3 also discloses that this EPDM rubber composition can be suitably used for a hose that conveys an oil-based medium.

Japanese Unexamined Patent Publication No. 2001-206987 Japanese Unexamined Patent Publication No. 2002-295734 Japanese Unexamined Patent Publication No. 2016-089120

As described above, various attempts have been made in the past to improve the oil resistance of the rubber composition containing EPDM or the crosslinked rubber, but there is still room for improvement in consideration of other properties.

In this respect, when the oil content in the rubber composition containing EPDM is increased, there is a certain limit to the improvement of oil resistance.
Further, when a polar rubber is blended with a rubber composition containing EPDM, the compatibility between EPDM and the polar rubber is poor, so that the strength of the crosslinked rubber may decrease. In addition, the heat resistance characteristic of EPDM may be reduced by blending with polar rubber. Therefore, it is desired to improve the oil resistance of the rubber composition and the crosslinked rubber body without impairing other properties.

Therefore, the present invention provides a rubber composition and a rubber crosslinked product having excellent oil resistance while maintaining other properties of an ethylene / α-olefin / non-conjugated polyene copolymer such as EPDM. The purpose.

The present inventors have found that adding a specific amount of EVA to EPDM can improve oil resistance without deteriorating other physical properties, and have completed the present invention.
The present invention relates to the following [1] to [8].

[1]
Ethylene, α-olefin, non-conjugated polyene copolymer (A) having 3 to 20 carbon atoms, 100 parts by mass, and
A rubber composition containing 3 to 40 parts by mass of an ethylene-vinyl acetate copolymer (B).
[2]
The rubber composition according to the above [1], wherein the vinyl acetate content in the ethylene-vinyl acetate copolymer (B) is 5 to 50% by mass.
[3]
A rubber crosslinked body obtained by cross-linking the rubber composition according to any one of [1] to [2].
[4]
A hose containing the rubber crosslinked body according to the above [3].
[5]
A multi-layer hose including an outer layer made of the rubber crosslinked body according to the above [3].
[6]
The hose according to the above [4] or the multi-layer hose according to the above [5], which is a water-based hose.
[7]
The hose according to the above [4] or the multi-layer hose according to the above [5], which is an air hose.
[8]
The hose according to the above [4] or the multi-layer hose according to the above [5], which is an automobile hose.

According to the present invention, it is possible to provide a rubber composition and a rubber crosslinked product having excellent oil resistance while maintaining other properties of an ethylene / α-olefin / non-conjugated polyene copolymer such as EPDM. it can.

[Rubber composition]
The rubber composition according to the present invention
Ethylene / α-olefin / non-conjugated polyene copolymer (A) having 3 to 20 carbon atoms and
Includes ethylene-vinyl acetate copolymer (B).

Here, in the present specification, the mass part of each component with respect to 100 parts by mass of the ethylene / α-olefin / non-conjugated polyene copolymer (A) having 3 to 20 carbon atoms may be referred to as “phr”. In addition, the expression "phr" is sometimes used for the amount of oil spread in the oil spread rubber. In that case, the amount of oil blended with respect to 100 parts by mass of the constituent rubber in the oil spread rubber is used. Represent.
Hereinafter, the rubber composition of the present invention and each component constituting the rubber composition of the present invention will be described in detail.

<Ethylene / α-olefin / non-conjugated polyene copolymer (A) having 3 to 20 carbon atoms>
Ethylene, α-olefin, non-conjugated polyene copolymer (A) having 3 to 20 carbon atoms constituting the rubber composition of the present invention (in the present specification, it may be simply referred to as "copolymer (A)". There is) is a copolymer of ethylene, an α-olefin having 3 to 20 carbon atoms, and a non-conjugated polyene. That is, the copolymer (A) contains a structural unit derived from ethylene, a structural unit derived from an α-olefin having 3 to 20 carbon atoms, and a structural unit derived from a non-conjugated polyene. In the rubber composition of the present invention, the copolymer (A) functions as a rubber main agent.

Here, in the present specification, the term "ethylene-derived structural unit" means a structural unit corresponding to ethylene, that is, a structural unit represented by −CH ₂ −CH ₂ −. “Structural units derived from α-olefins having 3 to 20 carbon atoms” and “structural units derived from non-conjugated polyenes” are also interpreted in the same manner, and structural units corresponding to α-olefins having 3 to 20 carbon atoms, respectively. , And the structural unit corresponding to the non-conjugated polyene.

The copolymer (A) used in the present invention is a rubber component, and may be a random copolymer or a block copolymer. The copolymer (A) is preferable because it is excellent in weather resistance, vulcanization property and the like.

Here, as the α-olefin having 3 to 20 carbon atoms, specifically, propylene, 1-butene, 4-methylpentene-1,1-hexene, 1-hexene, 1-octene, 1-nonene , 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-nonadecene, 1-eicosene, 9-methyldecene-1,11-methyldodecene -1 and 12-ethyltetradecene-1 and the like can be mentioned. Of these, propylene, 1-butene, 4-methylpentene-1, 1-hexene and 1-octene are preferable, and propylene is particularly preferable. These α-olefins may be used alone or in combination of two or more.

Also, as a specific example of non-conjugated polyene,
1,4-Hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 4,5-dimethyl-1,4-hexadiene, 7- Chain non-conjugated diene such as methyl-1,6-octadiene, 8-methyl-4-ethylidene-1,7-nonadien, 4-ethylidene-1,7-undecadien;
Norbornene, 5-methylene-2-norbornene, 5-vinyl-2-norbornene (VNB), 5-isopropenyl-2-norbornene, 5- (2-propenyl) -2-norbornene, 5-isobutenyl-2-norbornene, 5- (3-butenyl) -2-norbornene, 5- (1-methyl-2-propenyl) -2-norbornene, 5- (4-pentenyl) -2-norbornene, 5- (1-methyl-3-butenyl) ) -2-Norbornene, 5- (5-hexenyl) -2-Norbornene, 5- (1-methyl-4-pentenyl) -2-Norbornene, 5- (2,3-dimethyl-3-butenyl) -2- Norbornene, 5- (2-ethyl-3-butenyl) -2-norbornene, 5- (6-heptenyl) -2-norbornene, 5- (3-methyl-5-hexenyl) -2-norbornene, 5- (3) , 4-Dimethyl-4-pentenyl) -2-norbornene, 5- (3-ethyl-4-pentenyl) -2-norbornene, 5- (7-octenyl) -2-norbornene, 5- (2-methyl-6) -Heptenyl) -2-norbornene, 5- (1,2-dimethyl-5-hexenyl) -2-norbornene, 5- (5-ethyl-5-hexenyl) -2-norbornene, 5- (1,2,3 Unsaturated norbornene derivatives such as −trimethyl-4-pentenyl) -2-norbornene, 5-vinylidene-2-norbornene, 5-ethylidene-2-norbornene (ENB), 5-isopropylidene-2-norbornene, methyltetrahydroinden, And cyclic non-conjugated diene, such as dicyclopentadiene;
2,3-Diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornene, 4-ethylidene-8-methyl-1,7-nonadien, etc. Trien and the like can be mentioned. Of these non-conjugated polyenes, VNB and ENB are preferred.

These non-conjugated polyenes may be used alone or in combination of two or more.
Specific examples of the copolymer (A) include ethylene / propylene / 5-ethylidene-2-norbornene random copolymer, ethylene / propylene / 5-vinyl-2-norbornene random copolymer, and ethylene / propylene / 5-ethylidene. Examples thereof include -2-norbornene and 5-vinyl-2-norbornene random copolymers.

The copolymer (A) contains a structural unit derived from ethylene, preferably 40 to 80% by mass, more preferably 45 to 75% by mass, and further preferably 50 to 70% by mass. Further, the structural unit derived from the non-conjugated polyene is preferably contained in an amount of 2 to 15% by mass, more preferably 2 to 10% by mass, still more preferably 3 to 8% by mass. In the present specification, the content of the ethylene-derived structural unit in the copolymer (A) may be referred to as "ethylene content", and the content of the non-conjugated polyene-derived structural unit in the copolymer (A). The content is sometimes referred to as the "non-conjugated polyene content".

Further, in the above-mentioned copolymer (A), the mass ratio of the structural unit derived from ethylene to the structural unit derived from α-olefin having 3 to 20 carbon atoms is 90/10 to 40/60, preferably 60/40 to 60. It is 70/30. When this mass ratio is within the above range, a material having good mechanical strength can be obtained.

The ethylene / α-olefin / non-conjugated polyene copolymer having 3 to 20 carbon atoms constituting the copolymer (A) may be used alone or in combination of two or more. Is also good.

In the present invention, the copolymer that can form the copolymer (A) may be in the form of an oil-extended rubber obtained by adding oil, or may be in the form of a non-oil-extended rubber.
However, when an oil-extended rubber is used as the copolymer (A), the "parts by mass" and "mass%" of the copolymer (A) are oil-expanded unless otherwise specified. The remaining mass after subtracting the mass of oil contained in the oil-extended rubber from the total mass of rubber is used as a reference. For example, when an oil spreading rubber X (g) having an oil spreading amount a (phr) is adopted as the copolymer (A), the mass of the copolymer (A), which is a reference of "parts by mass", is Xx. It becomes 100 / (100 + a) (g).

<Ethylene-vinyl acetate copolymer (B)>
The rubber composition of the present invention is an ethylene-vinyl acetate copolymer (B) in addition to the above-mentioned copolymer (A) (in the present specification, it may be simply referred to as "copolymer (B)"). including. In the present invention, the ethylene-vinyl acetate copolymer (B) is an essential component, because the ethylene-vinyl acetate copolymer (sometimes also referred to as "EVA") is the above-mentioned copolymer (A) such as EPDM. ), And when combined with the copolymer (A), the oil resistance can be improved without deteriorating the various physical properties of the copolymer (A). ing. It is presumed that this is probably because the combination of the copolymer (A) with the copolymer (B) reduces the cross-linking density in the rubber cross-linked product obtained by cross-linking the rubber composition.

Here, the rubber composition of the present invention is compared with the rubber composition without the copolymer (B) when the ratio of the copolymer (B) to the copolymer (A) is within a certain range. , The oil resistance per elongation at the tensile break point tends to be high. On the other hand, if the ratio of the copolymer (B) to the copolymer (A) is excessively large, the rubber crosslinked product tends to be difficult to stretch. Based on these, in the present invention, the content of the copolymer (B) in the rubber composition is set to 3 to 40 parts by mass with respect to 100 parts by mass of the copolymer (A). The content of the copolymer (B) is preferably 5 to 30 parts by mass.

Further, the copolymer (B) preferably contains a structural unit derived from vinyl acetate in an amount of 5% by mass to 50% by mass, more preferably 15% by mass to 50% by mass, and 20% by mass to 50% by mass. % Is more preferable. When the content of the structural unit derived from vinyl acetate in the copolymer (B) is within the above range, the oil resistance due to the vinyl acetate structure is sufficiently exhibited, and the polyethylene structure causes the rubber component (copolymer (A)). It tends to be well compatible with the copolymer (B).

Here, in the present specification, the term "structural unit derived from vinyl acetate" refers to a structural unit corresponding to vinyl acetate, that is, a structure represented by −CH ₂ −CH (OC (= O) CH ₃ ) −. Means a unit. In the present specification, the content of the structural unit derived from ethylene in the copolymer (B) may be referred to as "ethylene content", and the content of the structural unit derived from vinyl acetate in the copolymer (B) is contained. The amount is sometimes referred to as the "vinyl acetate content".

<Crosslinking agent (C)>
The rubber composition of the present invention contains the above-mentioned copolymer (A) and copolymer (B), and in a normal embodiment, further contains a cross-linking agent (C). The cross-linking agent (C) constituting the rubber composition of the present invention is not particularly limited as long as the copolymer (A) can be cross-linked, and is usually used in the field of rubber such as sulfur compounds and peroxide-based cross-linking agents. It may be of various types used.

As one of the cross-linking agents (C) that can be used in the present invention, a sulfur-based compound (C1) can be mentioned.
Examples of the type of the sulfur compound (C1) include sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, selenium dithiocarbamate and the like. Of these, sulfur and tetramethylthiuram disulfide are preferable.

On the other hand, as a cross-linking agent (C) suitable in the present invention, a peroxide-based cross-linking agent (C2) can be mentioned.
As a peroxide-based cross-linking agent (C2),
1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) octane, Peroxyketals such as 1,1-bis (t-butylperoxy) cyclododecane, as well as
Di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, α, α'-bis (t-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (T-Butylperoxy) Hexane-3, t-Butylperoxy-2-ethylhexanoate, t-Butylperoxy-3,5,5-trimethylhexanoate, 2,5-dimethyl-2,5 -Dialkyl peroxides such as di (benzoyl peroxy) hexane can be mentioned.

The content of the cross-linking agent (C) in the rubber composition of the present invention is 0.01 to 10 parts by mass, preferably 0.01 to 7 parts by mass with respect to 100 parts by mass of the copolymer (A). is there.
Here, when the sulfur-based compound (C1) is used as the cross-linking agent (C), the content thereof is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the copolymer (A). ..
On the other hand, when the peroxide-based cross-linking agent (C2) is used as the cross-linking agent (C), the content thereof shall be 0.5 to 7 parts by mass with respect to 100 parts by mass of the copolymer (A). Is preferable.

<Other ingredients>
The rubber composition of the present invention contains the above-mentioned copolymer (A) and copolymer (B). The rubber composition of the present invention may further contain other components depending on the intended use.
Other components that can be contained in the rubber composition of the present invention include a reinforcing material (hereinafter referred to as "reinforcing material (D)"), a plasticizer, a vulcanization accelerator, a co-crosslinking agent, a vulcanization aid, a processing aid, and aging. Examples include various additives such as inhibitors, activators and antigelling agents.

Reinforcing material (D)
The rubber composition of the present invention may contain a reinforcing material (D) in order to enhance mechanical properties such as tensile strength, tear strength, and abrasion resistance when formed into a crosslinked product.
Examples of the type of the reinforcing material (D) include carbon black, silica, activated calcium carbonate, light calcium carbonate, heavy calcium carbonate, talc, clay and the like. These reinforcing materials may be used alone or in combination of two or more.

Among these, the reinforcing material (D) is one or more selected from the group consisting of carbon black and silica from the viewpoint of uniform dispersibility in the rubber matrix, excellent reinforcing property, and versatility (cost). preferable.

The type of carbon black is not particularly limited, and examples thereof include known types usually used in the rubber industry, such as furnace black (classified by ASTM D 1765), channel black, thermal black, and acetylene black, depending on the purpose of use. ..

Here, carbon black may be used by surface-treating it with a silane coupling agent or the like.
On the other hand, the type of silica is not particularly limited, and examples thereof include known dry silica and wet silica usually used in the rubber industry, depending on the purpose of use.

Further, as the heavy calcium carbonate, commercially available "Whiten SB" (trade name; Shiraishi Calcium Co., Ltd.) or the like can be used.
The type and blending amount of the reinforcing material (D) can be appropriately selected depending on the intended use, but is usually 10 to 400 parts by mass, preferably 10 to 350 parts by mass per 100 parts by mass of the copolymer (A). Is.

Plasticizer The rubber composition of the present invention may further contain a known plasticizer commonly used as a softener in the field of rubber, depending on its use.
Specific examples of such plasticizers include process oil (for example, "Diana Process Oil PS-430" (trade name; manufactured by Idemitsu Kosan Co., Ltd.)), lubricating oil, paraffin oil, liquid paraffin, petroleum asphalt, and Petroleum-based softeners such as vaseline; hydrocarbon-based softeners such as coal tar and coal tar pitch; fatty oil-based softeners such as paraffin oil, flaxseed oil, rapeseed oil, soybean oil, and palm oil; beeswax, carnauba wax, And waxes such as lanolin; fatty acids such as ricinolic acid, palmitic acid, stearic acid, barium stearate, calcium stearate, and zinc laurate or salts thereof; naphthenic acid, pine oil, and rosin or derivatives thereof; terpenic acid, petroleum Synthetic polymer substances such as resins, atactic polypropylene, and kumaron inden resins; ester-based softeners such as dioctyl phthalate, dioctyl adipate, and dioctyl sebacate; other microcrystallin wax, liquid polybutadiene, modified liquid polybutadiene, liquid thiocol , Hydrocarbon-based synthetic lubricating oil, tall oil, and sub (factis). Of these, petroleum-based softeners are preferable. Among the petroleum-based softeners, petroleum-based process oils are preferable, and among them, paraffin-based process oils, naphthen-based process oils, aroma-based process oils and the like are more preferable.

Here, the content of the plasticizer can be appropriately selected depending on the intended use, and is usually up to 200 parts by mass, preferably up to 150 parts by mass, and more preferably up to 130 parts by mass with respect to 100 parts by mass of the copolymer (A). The mass part is desirable.

Vulcanization Accelerator When the rubber composition according to the present invention contains a cross-linking agent (C), this rubber composition is in addition to the above-mentioned copolymer (A), copolymer (B) and cross-linking agent (C). May further contain a vulcanization accelerator.

Here, in the rubber composition according to the present invention, the content of the vulcanization accelerator is preferably 0.1 to 15 parts by mass, more preferably 0, with respect to 100 parts by mass of the copolymer (A). It is 5 to 10 parts by mass. When the vulcanization accelerator is contained in the rubber composition at such a content, the rubber composition has excellent cross-linking properties, and the generation of bloom in the obtained rubber cross-linked body can be further reduced.

Specific examples of the sulfide accelerator include N-cyclohexyl-2-benzothiazole sulfenamide (for example, "Sunceller CM" (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), N-oxydiethylene-2- Benzothiazole sulfenamide, N, N'-diisopropyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole (for example, "Suncella M" (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), 2- (4-morpholinodithio) penzothiazole (for example, "Noxeller MDB-P" (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), 2- (2,4-dinitrophenyl) mercaptobenzothiazole, 2- (4) 2,6-diethyl-4-morpholinothio) Thiazoles such as benzothiazole and dibenzothiadyldisulfide; guanidines such as diphenylguanidine, triphenylguanidine and diorsotrilguanidine; acetaldehyde-aniline condensate, butylaldehyde-aniline Condensate, aldehyde amine type; imidazoline type such as 2-mercaptoimidazolin; thiourea type such as diethyl thiourea and dibutyl thiourea; tetramethyl thiuram monosulfide, tetramethyl thiuram disulfide (for example, "Suncella TT" (trade name; Sanshin Kagaku) (Manufactured by Kogyo Co., Ltd.), etc.), tetraethylthiuram disulfide (for example, "Sunceller TET" (trade name; manufactured by Sanshin Kagaku Kogyo Co., Ltd.), etc.) and other thiuram-based; Dithioate systems such as zinc (for example, "Suncella BZ" (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), telluryl diethyldithiocarbamate, etc .; ethylenethiourea (for example, "Suncella 22-C" (trade name; Sanshin Chemical Industry Co., Ltd.) (Manufactured by Shinkagaku Kogyo Co., Ltd.), etc.), Thiourea type such as N, N'-diethylthiourea; Zantate type such as zinc dibutylxatogenate; Other zinc flower (for example, "META-Z102" (trade name; Inoue Lime Industry Co., Ltd.) Zinc oxide) such as)) and the like.

Co-crosslinking agent When a peroxide-based cross-linking agent (C2) is used as the cross-linking agent (C), the rubber composition according to the present invention includes the copolymer (A), the copolymer (B), and the copolymer (B). In addition to the cross-linking agent (C), an appropriate co-cross-linking agent can be further contained, if necessary, for the purpose of improving physical properties and vulcanization rate.

As an example of a co-crosslinking agent
Triallyl isocyanurate (TAIC) such as Tyke (trade name; manufactured by Mitsubishi Chemical Corporation);
Triallyl cyanurate (TAC) such as Tuck (trade name; manufactured by Musashino Chemical Laboratory Co., Ltd.);
Polyethylene glycol dimethacrylate (PEGDM) such as Blemmer PDE-100 (trade name; manufactured by Nichiyu Co., Ltd.), tetrahydrofurfuryl methacrylate (THMMA) such as acrylic ester THF (trade name; manufactured by Mitsubishi Chemical Co., Ltd.), sun ester Ethylene glycol dimethacrylate (EDMA) such as EG (trade name: manufactured by Sanshin Chemical Industry Co., Ltd.) and Acryester ED (trade name: manufactured by Mitsubishi Chemical Co., Ltd.), Acryester BD (trade name: manufactured by Mitsubishi Chemical Co., Ltd.) ), Dimethacrylic acid 1,3-butylene glycol (BDMA), Sun Ester TMPMA (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.), Acryester TMP (trade name; manufactured by Mitsubishi Chemical Co., Ltd.) and High Cloth M (trade name: manufactured by Mitsubishi Chemical Co., Ltd.) Trade name: Trimethylol acrylate propane (TMPMA) such as Seiko Kagaku Co., Ltd., a methacrylic ester having two or more functional groups that can participate in the cross-linking reaction;
Dialyl Phthalate (DAP)
And so on.

The amount of the copolymer (A) added is appropriately about 1 to 10 parts by mass with respect to 100 parts by mass of the copolymer (A).
Further, in the rubber composition of this embodiment, triallyl isocyanurate (TAIC) such as methacrylic acid ester or Tyke (trade name; manufactured by Mitsubishi Chemical Co., Ltd.) is used during vulcanization using a peroxide-based cross-linking agent. May be further added as a vulcanization aid.

Vulcanization Auxiliary Agent When the rubber composition according to the present invention contains a cross-linking agent (C), the rubber composition may contain the above-mentioned copolymer (A), copolymer (B) and cross-linking agent (C). May further contain a vulcanization aid.

Specific examples of the vulcanization aid include magnesium oxide, zinc oxide (for example, "META-Z102" (trade name; manufactured by Inoue Lime Industry Co., Ltd.) and zinc oxide such as zinc oxide 2 types). The content is usually 1 to 20 parts by mass with respect to 100 parts by mass of the copolymer (A).

Processing aid The rubber composition according to the present invention may further contain a processing aid in addition to the above-mentioned copolymer (A) and copolymer (B).

As the processing aid, a compound used for ordinary rubber processing can be used. Specifically, higher fatty acids such as ricinolic acid, stearic acid, partiminic acid, and lauric acid; salts of higher fatty acids such as barium stearate, zinc stearate, and calcium stearate; ricinolic acid, stearic acid, partimic acid, lauric acid, etc. Examples of higher fatty acid esters of.

Such a processing aid is usually used in a ratio of 10 parts by mass or less, preferably 5 parts by mass or less with respect to 100 parts by mass of the copolymer (A), but is appropriately used depending on the required physical property values. It is desirable to determine the optimum amount.

Anti-aging agent The rubber product produced from the rubber composition according to the present invention may contain an anti-aging agent in order to further extend the product life. In addition, examples of the anti-aging agent include conventionally known anti-aging agents such as amine-based anti-aging agents, phenol-based anti-aging agents, and sulfur-based anti-aging agents.

Specifically, aromatic secondary amine-based antiaging agents such as phenylbutylamine, N, N-di-2-naphthyl-p-phenylenediamine, dibutylhydroxytoluene, tetrakis- [methylene-3- (3', 3',). 5'-di-t-butyl-4'-hydroxyphenyl) propionate] Phenolic anti-aging agents such as methane; bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-t-butylphenyl ] Thioether-based anti-aging agents such as sulfide; Dithiocarbamate-based anti-aging agents such as nickel dibutyldithiocarbamate; 2-mercaptobenzoylimidazole, zinc salt of 2-mercaptobenzoimidazole, dilaurylthiodipropionate, distearylthiodipro Examples thereof include sulfur-based anti-aging agents such as pionate.

These antioxidants can be used alone or in combination of two or more, and the content of such antioxidants is usually 0, based on 100 parts by mass of the copolymer (A). It is 3 to 10 parts by mass, preferably 0.5 to 7.0 parts by mass, and more preferably 0.7 to 5.0 parts by mass. When the content of the anti-aging agent is within the above range, the inhibition of vulcanization at the time of cross-linking of the rubber composition can be reduced, and the generation of bloom in the obtained cross-linked rubber body can be reduced.

Activator The rubber composition of the present invention may contain one or more activators, if necessary. Specific examples of the activator include di-n-butylamine, dicyclohexylamine, monoethanolamine, "Acting B" (trade name; manufactured by Yoshitomi Pharmaceutical Co., Ltd.), and "Acting SL" (trade name; Yoshitomi Pharmaceutical Co., Ltd.). Amines such as (manufactured by); diethylene glycol, polyethylene glycol, lecithin, triallyl trimellitate, zinc compounds of aliphatic and aromatic carboxylic acids (eg, "Structol activator 73", "Structor IB 531" and "Structor FA541" Product name; Amine-based activator such as Schill &Seilacher); Zinc peroxide modifier such as "ZEONET ZP" (Product name: Nippon Zeon Co., Ltd.); Octadecyltrimethylammonium bromide, synthetic hydrotalcite, special Examples thereof include a quaternary ammonium compound (for example, "Arcard 2HF" (trade name; manufactured by Lion Axo Co., Ltd.)).
The content of the activator is 0.2 to 10 parts by mass, preferably 0.3 to 5 parts by mass, and more preferably 0.5 to 4 parts by mass with respect to 100 parts by mass of the copolymer (A). ..

Antigelling agent The rubber composition of the present invention may contain an antigelling agent, if necessary. Examples of the antigelling agent include bis [3- (triethoxysilyl) propyl] tetrasulfide. This bis [3- (triethoxysilyl) propyl] tetrasulfide is available as a commercially available product such as "Si69" (manufactured by Evonik Industries).

The content of the antigelling agent is 0.1 to 5 parts by mass, preferably 0.2 to 2 parts by mass, and more preferably 0.5 to 1 part by mass with respect to 100 parts by mass of the copolymer (A). Is.
The rubber composition of the present invention may further contain other additives, if necessary. Examples of other additives include heat-resistant stabilizers, weather-resistant stabilizers, antistatic agents, colorants, lubricants, thickeners and the like.

<Manufacturing method of rubber composition>
The rubber composition of the present invention comprises the above-mentioned predetermined parts by mass of the copolymer (A) and the copolymer (B), a cross-linking agent (C) to be blended if necessary, and the above-mentioned "other components" to be blended if necessary. ", It can be prepared by the same method as the general method for preparing a rubber compound.

For example, using an internal mixer such as a Banbury mixer, a kneader, or an intermix, each of the above-mentioned components is preferably prepared at a temperature of 80 to 190 ° C., more preferably 80 to 170 ° C., preferably for 2 to 20 minutes. , More preferably after kneading for 3 to 10 minutes, kneading at a roll temperature of 40 to 80 ° C. for 3 to 30 minutes using a roll such as an open roll or a kneader, and then extruding / dispensing the kneaded product. Can be prepared. Further, when the kneading temperature in the internal mixers is low, a vulcanization accelerator or a vulcanization aid may be kneaded at the same time. Further, the kneading using the internal mixers may be performed by using rolls instead of the internal mixers depending on the kneading temperature and the like.

<Rubber crosslinked body>
The rubber composition of the present invention can be used as a raw material for a rubber crosslinked product. The rubber crosslinked body of the present invention is obtained by crosslinking the above-mentioned rubber composition. The rubber crosslinked body of the present invention has high oil resistance. Therefore, it is very useful as a rubber product in each field where oil resistance is required.

Here, the rubber crosslinked product of the present invention can be obtained by cross-linking the above-mentioned rubber composition. In order to produce a crosslinked product from the composition of the present invention, an unvulcanized rubber composition is prepared by the method as described above in the same manner as in the case of vulcanizing general rubber, and then this rubber composition is prepared. May be vulcanized after being formed into the intended shape.

The unvulcanized rubber composition prepared as described above can be molded and vulcanized by various molding methods, but is molded and vulcanized by mold molding such as compression molding, injection molding and injection molding. It can exert its characteristics most in the field.

In the case of compression molding, for example, a pre-weighed unvulcanized rubber composition is placed in a mold, and after closing the mold, the crosslinked product is heated at a temperature of 120 to 270 ° C. for 30 seconds to 120 minutes. Is obtained.

In the case of injection molding, for example, a ribbon-shaped or pellet-shaped rubber composition is supplied to the pot in a preset amount by a screw. Subsequently, the preheated rubber composition is fed into the mold by a plunger in 1 to 20 seconds. After injecting the rubber composition, it is heated at a temperature of 120 to 270 ° C. for 30 seconds to 120 minutes to obtain a desired crosslinked product.

In the case of injection molding, for example, a pre-weighed rubber composition is placed in a pot and injected into a mold by a piston in 1 to 20 seconds. After injecting the rubber composition, the crosslinked product is obtained by heating at a temperature of 120 to 270 ° C. for 30 seconds to 120 minutes.

Applications of the rubber crosslinked product of the present invention thus obtained include rubber products in various fields in which oil resistance, particularly oil resistance to machine oil and fuel, is required.
A hose is particularly preferable among such rubber products. That is, the hose of the present invention contains the rubber crosslinked body. The hose of the present invention is particularly excellent in oil resistance. The hose of the present invention may be a single-layer hose made of the rubber crosslinked body, or may be a multi-layer hose including a layer made of the rubber crosslinked body.

Here, in one of the preferred embodiments of the present invention, the multilayer hose includes an outer layer made of the rubber crosslinked body. Further, the multi-layer hose may further have an inner layer inside the outer layer, similarly to a general multi-layer hose. In this case, the inner layer may be made of the crosslinked rubber, or acrylonitrile butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber (HNBR), acrylic rubber (ACM), ethylene acrylate rubber (AEM). ), Fluoro rubber, fluororesin, polyamide resin, etc., may be made of a material other than the above-mentioned rubber crosslinked body. Such a multi-layer hose may consist of only the outer layer and the inner layer, and the outer layer and the inner layer may be laminated in this order, or the outer layer and the reinforcing layer or the intermediate rubber layer may be laminated. Other layers such as the above and the inner layer may be further included in this order.
Examples of applications of the hose of the present invention and the laminated hose of the present invention include water-based hoses, air hoses, hoses for automobiles, and the like.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. The measurement method of each physical property is as follows.
<Evaluation of unvulcanized rubber physical properties>
(Moony viscosity (ML (1 + 4) 125 ° C.)
The Mooney viscosity (ML (1 + 4) 125 ° C.) at 125 ° C. was measured under the condition of 125 ° C. using a Mooney viscometer (SMV202 type manufactured by Shimadzu Corporation) in accordance with JIS K6300.

<Evaluation of vulcanized rubber physical properties>
(Tensile breaking point stress, tensile breaking point elongation)
The tensile breaking point stress and the tensile breaking point elongation of the sheet made of the rubber crosslinked body were measured by the following methods.

A sheet made of a rubber crosslinked body is punched out to prepare a No. 3 dumbbell test piece described in JIS K 6251 (2017), and this test piece is used to measure a measurement temperature 23 according to the method specified in JIS K 6251. Tensile tests were conducted under the conditions of ° C., relative humidity of 50%, and tensile speed of 500 mm / min. Tensile stress (25% modulus (M25)) when the elongation rate was 25%, and tensile strength when the elongation rate was 50%. Stress (50% modulus (M50)), tensile stress when elongation is 100% (100% modulus (M100)), tensile stress when elongation is 200% (200% modulus (M200)), Tensile stress (300% modulus (M300)), tensile breaking point stress (TB) and tensile breaking point elongation (EB) when the elongation rate was 300% were measured.

(Crosslink density)
After cutting the sheet-shaped sample to a size of 20 mm × 20 mm × 2 mm, it is immersed in toluene for 37 ° C. × 72 hours to swell according to JIS K 6258 (1993), and the effective network chain is according to the formula (B) of Fly-Rehner. The density (crosslink density) was calculated.

In formula (B), ν (pieces / cm ³ ) is the effective mesh chain density (crosslink density), which is the number of effective mesh chains in 1 cm ^{3 of} pure rubber, and V _R is the pure rubber in the swollen crosslinked rubber. V ₀ is the molecular volume of the solvent, μ is the rubber-solvent interaction constant = 0.49, and A is the Avogadro number.

(Oil resistance)
Using IRM903 as the test solution, the sample was immersed in the test solution at 100 ° C. for 72 hours, the pre-test volume (V1; cm ³ ) and the post-test volume (V2; cm ³ ) were measured, and the weight change rate was calculated from the following formula. Was calculated.
ΔV (%) = (V2-V1) / V1

<Regarding the components used in Examples and Comparative Examples>
In the examples and comparative examples, the following were used as the ethylene / propylene / non-conjugated polyene copolymer and the ethylene / vinyl acetate copolymer:
EPDM: Ethylene / propylene / ENB copolymer (trade name: Mitsui EPT ™ X-3042E (manufactured by Mitsui Chemicals, Inc.)), ML (1 + 4) 100 ° C: 37, ethylene content: 66% by mass, ENB content : 4.7% by mass, oil spread: 120 phr.
EVA: Ethylene-vinyl acetate copolymer (trade name: EVAFlex (trade name) EV45LX (manufactured by Mitsui Chemicals, DuPont Polychemical Co., Ltd.)), vinyl acetate content: 46% by mass, density: 980 kg / m ³ , MFR ( 190 ° C., 2.16 kg load): 2.5 g / 10 minutes.

[Example 1]
As the first step, using MIXTRON BB MIXER (manufactured by Kobe Steel, BB-4 type, volume 2.95 L, rotor 4WH),
As the copolymer (A), 220 parts by mass of EPDM (corresponding to 100 parts by mass of the copolymer component amount) and
As the copolymer (B), 5 parts by mass of EVA and
As the reinforcing material (D), FEF carbon black (Asahi # 60UG: manufactured by Asahi Carbon Co., Ltd.) 180 parts by mass, SRF carbon black (Asahi # 50G: manufactured by Asahi Carbon Co., Ltd.) 60 parts by mass, and talc. (Mystron vapor: manufactured by Nippon Mystron Co., Ltd.) 50 parts by mass and
As a vulcanization aid, 5 parts by mass of zinc oxide (2 types of zinc oxide: manufactured by HakusuiTech Co., Ltd.)
As a processing aid, 1 part by mass of stearic acid (bead stearic acid camellia: manufactured by NOF CORPORATION) and
As an activator, 1 part by mass of polyethylene glycol (PEG # 4000: manufactured by NOF CORPORATION) and
As a silane coupling agent (antigel), 0.5 parts by mass of bis [3- (triethoxysilyl) propyl] tetrasulfide (Si69: manufactured by Evonik Industries) was kneaded to obtain a compound. The kneading conditions were a rotor rotation speed of 50 rpm, a floating weight pressure of 3 kg / cm ² , and a kneading time of 5 minutes, and the kneading discharge temperature was 120 ° C.

The composition of the formulation obtained in the first step is shown in Table 1. Here, regarding the blending amount of EPDM, the value shown in the upper row represents the total amount of the oil-extended rubber, and the value shown in the diagonal brackets in the lower row is the amount of the copolymer component (that is, the oil-extended rubber). The remaining amount obtained by subtracting the amount of oil contained in the oil-extended rubber from the total amount of rubber).

Next, as a second step, using an 8-inch roll on the formulation obtained in the first step,
Triallyl isocyanurate (TAIC: manufactured by Mitsubishi Chemical Corporation) as a co-crosslinking agent, 2 parts by mass,
As a cross-linking agent (C), 10.2 parts by mass of dicumyl peroxide (Park Mill D-40: manufactured by NOF CORPORATION; purity 40%) was added and kneaded to obtain an uncrosslinked rubber composition. The kneading conditions were such that the roll temperature was front roll / rear roll: 50 ° C./50 ° C., the roll rotation speed was front roll / rear roll: 18 rpm / 15 rpm, and the roll gap was 2 mm, and the kneading time was 8 minutes. The composition of the uncrosslinked rubber composition is shown in Table 1.
The physical properties of the obtained uncrosslinked rubber composition (unvulcanized rubber physical properties) were measured based on the above-mentioned "evaluation of unvulcanized rubber physical properties". The results are shown in Table 1.

Further, this uncrosslinked rubber composition was crosslinked by pressing at 180 ° C. for 10 minutes using a press molding machine to prepare a rubber sheet having a thickness of 2 mm as a rubber crosslinked body. The physical properties of the obtained rubber sheet (vulcanized rubber physical properties) were measured based on the above-mentioned "evaluation of vulcanized rubber physical properties". Specifically, the durometer A hardness of the obtained rubber sheet, tensile stress (M25, M50, M100, M200, M300), breaking point strength TB (MPa), breaking point elongation EB (%), cross-linking density, and Oil resistance was measured respectively. The results are shown in Table 2 below.

[Example 2]
The procedure was the same as in Example 1 except that the amount of the cross-linking agent (C) was changed to 17.0 parts by mass.
Table 1 shows the composition of the uncrosslinked rubber composition and the physical properties of the unvulcanized rubber, and Table 2 shows the results of the physical properties of the vulcanized rubber.

[Example 3]
The procedure was the same as in Example 1 except that the amount of the copolymer (B) was changed to 10 parts by mass.
Table 1 shows the composition of the uncrosslinked rubber composition and the physical properties of the unvulcanized rubber, and Table 2 shows the results of the physical properties of the vulcanized rubber.

[Example 4]
The procedure was the same as in Example 2 except that the amount of the copolymer (B) was changed to 10 parts by mass.
Table 1 shows the composition of the uncrosslinked rubber composition and the physical properties of the unvulcanized rubber, and Table 2 shows the results of the physical properties of the vulcanized rubber.

[Example 5]
The procedure was the same as in Example 1 except that the amount of the copolymer (B) was changed to 20 parts by mass.
Table 1 shows the composition of the uncrosslinked rubber composition and the physical properties of the unvulcanized rubber, and Table 2 shows the results of the physical properties of the vulcanized rubber.

[Example 6]
The procedure was the same as in Example 2 except that the amount of the copolymer (B) was changed to 20 parts by mass.
Table 1 shows the composition of the uncrosslinked rubber composition and the physical properties of the unvulcanized rubber, and Table 2 shows the results of the physical properties of the vulcanized rubber.

[Comparative Example 1]
The procedure was the same as in Example 1 except that the copolymer (B) was not blended and the amount of the cross-linking agent (C) was changed to 6.8 parts by mass.
Table 1 shows the composition of the uncrosslinked rubber composition and the physical properties of the unvulcanized rubber, and Table 2 shows the results of the physical properties of the vulcanized rubber.

[Comparative Example 2]
The procedure was the same as in Example 1 except that the copolymer (B) was not blended.
Table 1 shows the composition of the uncrosslinked rubber composition and the physical properties of the unvulcanized rubber, and Table 2 shows the results of the physical properties of the vulcanized rubber.

Claims (8)

Ethylene, α-olefin, non-conjugated polyene copolymer (A) having 3 to 20 carbon atoms, 100 parts by mass, and
A rubber composition containing 3 to 40 parts by mass of an ethylene-vinyl acetate copolymer (B). The rubber composition according to claim 1, wherein the vinyl acetate content in the ethylene-vinyl acetate copolymer (B) is 5 to 50% by mass. A rubber crosslinked body obtained by cross-linking the rubber composition according to any one of claims 1 and 2. A hose containing the rubber crosslinked body according to claim 3. A multi-layer hose including an outer layer made of the rubber crosslinked body according to claim 3. The hose according to claim 4 or the multilayer hose according to claim 5, which is a water-based hose. The hose according to claim 4 or the multilayer hose according to claim 5, which is an air hose. The hose according to claim 4 or the multilayer hose according to claim 5, which is an automobile hose.