JP2011236270A - Rubber composition and hose - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition having both excellent scorch time and excellent characteristics after performing vulcanization.SOLUTION: The rubber composition comprises: 100 pts.mass of a rubber component; 1-15 pts.mass of a predetermined bis-citraconimido compound; and 0.5-10 pts.mass of a crosslinking initiator, wherein the rubber component comprises chlorosulfonated polyethylene and/or alkylated chlorosulfonated polyethylene.

Description

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

  Conventionally, a rubber composition obtained by vulcanizing lead-vulcanized chlorosulfonated polyethylene (hereinafter also referred to as “CSM”) or alkylated chlorosulfonated polyethylene (hereinafter also referred to as “ACSM”) is, for example, a power steering hose (hydraulic type Used in hoses used in power steering piping.

  In recent years, CSM has been vulcanized with a bismaleimide compound in response to a demand for deleading while environmental awareness is increasing (see, for example, Patent Document 1).

JP 2009-126877 A

  However, when a bismaleimide compound is used as a vulcanizing agent for CSM or ACSM, the properties after vulcanization such as tensile strength, elongation at break, and hardness are equivalent to those of a lead vulcanized rubber composition, There was a problem that the scorch time was shortened.

  Then, an object of this invention is to provide the rubber composition which is excellent in the scorch time, and the characteristic after vulcanization is also favorable.

As a result of intensive studies to solve the above problems, the present inventor has excellent scorch time by blending a specific amount of a predetermined biscitraconimide compound and a crosslinking initiator with respect to CSM and / or ACSM, and The present inventors have found that a rubber composition having good characteristics after vulcanization can be obtained, thereby completing the present invention.
That is, the present invention provides the following (1) to (4).

  (1) 100 parts by mass of a rubber component containing chlorosulfonated polyethylene and / or alkylated chlorosulfonated polyethylene, 1 to 15 parts by mass of a biscitraconimide compound represented by the following general formula (I), and a crosslinking initiator 0 A rubber composition containing 5 to 10 parts by mass.

In the formula, A is a divalent group selected from the group consisting of an alkylene group, an alkali-ylene group, a cycloalkylene group, an arylene group, an aralkylene group and an alkenylene group, and R ¹ is a hydrogen atom or 1 to 18 carbon atoms. And a plurality of R ^{1 s} may be the same or different from each other.

  (2) The rubber composition according to (1), wherein the rubber component contains the chlorosulfonated polyethylene and / or the alkylated chlorosulfonated polyethylene in an amount of more than 50% by mass.

  (3) The rubber composition according to (1) or (2), wherein the biscitraconimide compound is bis (citraconimidomethyl) benzene represented by the following formula (II).

  (4) A hose comprising an inner tube, a reinforcing layer disposed on the outer peripheral side of the inner tube, and an outer tube disposed on the outer peripheral side of the reinforcing layer, the inner tube and / or the outer tube Is a hose made of the rubber composition according to any one of (1) to (3) above.

  According to the present invention, it is possible to provide a rubber composition having excellent scorch time and good characteristics after vulcanization.

It is a perspective view which cuts and shows each layer of a hose.

  The present invention is described in detail below. The rubber composition of the present invention comprises 100 parts by mass of a rubber component containing chlorosulfonated polyethylene and / or alkylated chlorosulfonated polyethylene, 1 to 15 parts by mass of a biscitraconimide compound represented by the above general formula (I), And a rubber composition containing 0.5 to 10 parts by mass of a crosslinking initiator.

<Rubber component>
The rubber component contained in the rubber composition of the present invention includes chlorosulfonated polyethylene (CSM) and / or alkylated chlorosulfonated polyethylene (ACSM).
In addition, when the said rubber component contains rubber components other than CSM or ACSM, the rubber component will not be specifically limited if it is a rubber component which can be bridge | crosslinked, For example, a diene rubber etc. are mentioned.

  The content of CSM or ACSM in the rubber component (when CSM and ACSM are used in combination) is preferably more than 50% by mass, more than 80% by mass More preferably.

(CSM)
The CSM contained in the rubber component is not particularly limited as long as it has a chlorosulfonyl group as a crosslinking point, and conventionally known linear or branched chlorosulfonated polyethylene can be used. And polyethylene chlorinated and chlorosulfonated using chlorine and sulfurous acid gas.

  The Mooney viscosity at 100 ° C. of the CSM is preferably 20 to 100, and more preferably 30 to 80. If the Mooney viscosity of the CSM is 20 or more, the rubber composition has excellent characteristics after vulcanization (tensile strength, elongation at break), and if the Mooney viscosity of the CSM is 100 or less, the processability of the rubber composition ( Excellent mixing and extrusion.

  The chlorine content of the CSM is preferably 20 to 50% by mass, and more preferably 23 to 45% by mass. If the chlorine content of the CSM is 20% by mass or more, the oil resistance of the rubber composition is excellent, and if the chlorine content of the CSM is 50% by mass or less, the compression set of the rubber composition is small.

  The sulfur content of the CSM is preferably 0.1 to 4% by mass, more preferably 0.2 to 1.8% by mass, and 0.5 to 1.5% by mass. Further preferred. When the sulfur content of the CSM is 0.1% by mass or more, the vulcanization density when the rubber composition is vulcanized is excellent, and when the sulfur content of the CSM is 4% by mass or less, the rubber composition is added. Excellent rubber elasticity after vulcanization.

Commercially available CSM can also be used as the CSM. For example, TOSO-CSM (registered trademark) 530 (manufactured by Tosoh Corporation, Mooney viscosity (ML _{1 + 4} , 100 ° C.) 56, chlorine content 35 mass%, sulfur content 1. 0 mass%), Hypalon (registered trademark, the same applies hereinafter) 40 (manufactured by DuPont, Mooney viscosity (ML _{1 + 4} , 100 ° C.) 55, chlorine content 35 mass%, sulfur content 1.0 mass%), etc. Available as

(ACSM)
The ACSM contained in the rubber component is not particularly limited as long as it has a chlorosulfonyl group as a crosslinking point. For example, a homopolymer of an olefin other than ethylene or a copolymer of an olefin other than ethylene and ethylene The polyolefin which is chlorinated and chlorosulfonated using chlorine and sulfurous acid gas.
In addition, the kind and content of olefins other than ethylene are not particularly limited as long as the chlorine content and sulfur content of the ACSM are within the ranges shown below.

  The ACSM has a Mooney viscosity at 100 ° C. of preferably 20 to 100, more preferably 30 to 80. If the Mooney viscosity of the ACSM is 20 or more, the rubber composition has excellent properties after vulcanization (tensile strength, elongation at break). If the Mooney viscosity of the ACSM is 100 or less, the processability of the rubber composition ( Excellent mixing and extrusion.

  The ACSM has a chlorine content of preferably 10 to 35% by mass, more preferably 20 to 35% by mass, and even more preferably 25 to 33% by mass. When the chlorine content of the ACSM is 10% by mass or more, the oil resistance of the rubber composition is excellent, and when the chlorine content of the ACSM is 35% by mass or less, the compression set of the rubber composition becomes small.

  The sulfur content of the ACSM is preferably 0.1 to 4% by mass, more preferably 0.2 to 1.8% by mass, and 0.5 to 1.5% by mass. Further preferred. If the ACSM sulfur content is 0.1% by mass or more, the rubber composition is excellent in vulcanization density, and if the ACSM sulfur content is 4% by mass or less, the rubber composition is vulcanized. Excellent rubber elasticity after vulcanization.

Commercially available ACSM can be used as the ACSM. For example, ECTOS (registered trademark) 8510 (manufactured by Tosoh Corporation, Mooney viscosity (ML _{1 + 4} , 100 ° C.) 40, chlorine content 30% by mass, sulfur content 0.9% by mass %), AXIUM (registered trademark, the same applies below) HPR-6367 (DuPont product, Mooney viscosity (ML _{1 + 4} , 100 ° C.) 43, chlorine content 27 mass%, sulfur content 1.0 mass%), etc. Available as

<Biscitraconimide compound>
The biscitraconimide compound contained in the rubber composition of the present invention is represented by the following general formula (I).

In the formula, A is a divalent group selected from the group consisting of an alkylene group, an alkali-ylene group, a cycloalkylene group, an arylene group, an aralkylene group and an alkenylene group, and R ¹ is a hydrogen atom or 1 to 18 carbon atoms. And a plurality of R ^{1 s} may be the same or different from each other.

Specific examples of the alkylene group include methylene group, ethylene group, n-propylene group, isopropylene group, n-butylene group, isobutylene group, sec-butylene group, tert-butylene group, hexylene group, n-octylene group, n -A dodecylene group, a stearylene group, etc. are mentioned.
The alkali-ylene group is a group in which two alkylene groups are bonded to an aromatic ring such as benzene. Specific examples thereof include an o-xylylene group, an m-xylylene group, and a p-xylylene group. It is done.
Specific examples of the cycloalkylene group include a cyclohexylene group.
The arylene group means a divalent monocyclic or polycyclic aromatic hydrocarbon group, and specific examples thereof include 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group. Biphenyl-4,4′-diyl group, diphenylmethane-4,4′-diyl group, 3,3′-dimethylbiphenyl-4,4′-diyl group, and the like.
The aralkylene group refers to —Ar—Alk— or —Alk—Ar— (wherein Ar represents an arylene group and Alk represents an alkylene group), and specific examples thereof include a benzylene group (—C ₆ H ₄ -CH ₂ - or _-CH 2 _-C 6 _{H 4} -), and the like.
Specific examples of the alkenylene group include a vinylene group and a propenylene group.

  A in the formula is not particularly limited as long as it is a divalent group selected from the group consisting of the above-mentioned groups, but from the viewpoint of usefulness of properties after vulcanization of the rubber composition, an alkali-ylene group or an arylene group Group is preferred, and an alkali-lene group is more preferred.

R ¹ in the formula is not particularly limited as long as it is a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. Specific examples of such an alkyl group include a methyl group, an ethyl group, n- Examples include propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, hexyl group, n-octyl group, n-dodecyl group, stearyl group and the like.
R ¹ in the formula is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom, from the viewpoint of crosslinking reaction activity with the CSM or ACSM.

  Specifically, as the biscitraconimide compound, for example, bis (citraconimidomethyl) benzene represented by the following formula (II) can be preferably used.

  Content of the said biscitraconimide compound is 1-15 mass parts with respect to 100 mass parts of said rubber components, and it is preferable that it is 3-7 mass parts. When the content of the biscitraconimide is within this range, the scorch time of the rubber composition of the present invention obtained is superior to the scorch time than the rubber composition containing the bismaleimide compound.

When a biscitraconimide compound is used as a vulcanizing agent, the scorch time is superior to that when a bismaleimide compound having C = C is used as a vulcanizing agent. This is considered to be because when the group represented by —CH ₂ —R ¹ is bonded, the reactivity with the chlorosulfonyl group which is a crosslinking point of the CSM or ACSM is weaker than that of the bismaleimide compound.

<Crosslinking initiator>
The crosslinking initiator contained in the rubber composition of the present invention is 0.5 to 10 parts by mass and 1 to 6 parts by mass with respect to 100 parts by mass of the rubber component because the scorch time of the rubber composition is excellent. Part.

  As the crosslinking initiator, for example, 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, 2-mercaptobenzimidazole, dibutyldithiocarbamic acid and the like can be preferably used.

  Furthermore, the rubber composition of the present invention contains various additives such as an acid acceptor, a pigment (dye), a processing aid, an antioxidant, and a plasticizer, as necessary, without departing from the object of the present invention. Can be contained.

The acid acceptor captures hydrochloric acid generated from CSM or the like, and examples of such an acid acceptor include magnesium oxide (MgO), calcium hydroxide (Ca (OH) ₂ ), and the like.

  Specific examples of the pigment include inorganic pigments such as titanium oxide, ultramarine blue, bengara, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride, sulfate, etc .; azo pigment, phthalocyanine pigment, quinacridone pigment, quinacridone Quinone pigment, dioxazine pigment, anthrapyrimidine pigment, anthanthrone pigment, indanthrone pigment, flavanthrone pigment, perylene pigment, perinone pigment, diketopyrrolopyrrole pigment, quinonaphthalone pigment, anthraquinone pigment, thioindigo pigment, benzimidazolone pigment, iso And organic pigments such as indoline pigments and carbon black.

  Specific examples of processing aids include, for example, higher fatty acids such as linoleic acid, ricinoleic acid, stearic acid, palmitic acid, and lauric acid; salts of higher fatty acids such as barium stearate and calcium stearate; esters of the above higher fatty acids. And the like.

  Specific examples of the antioxidant include butylhydroxytoluene (BHT), butylhydroxyanisole (BHA), nickel dibutyldithiocarbamate (NBC) 2,2,4-trimethyl-1,2-dihydroquinoline polymer. (TMDQ) and the like.

  Specific examples of the plasticizer include alkyl trimellitate plasticizers such as triisononyl trimellitate.

  Although the manufacturing method of the rubber composition of the present invention is not particularly limited, for example, an unvulcanized rubber composition containing each of the above-described components is mixed with a known method and apparatus (for example, a Banbury mixer, a kneader, a roll, etc.). And can be prepared by kneading or the like.

  The rubber composition of the present invention is not particularly limited except that the biscitraconimide compound is used as a vulcanizing agent, and can be vulcanized under conventionally known vulcanizing conditions.

  Next, the hose of the present invention will be described. The hose of the present invention is a hose comprising an inner tube, a reinforcing layer disposed on the outer peripheral side of the inner tube, and an outer tube disposed on the outer peripheral side of the reinforcing layer, the inner tube and / or The outer tube is a hose made of the rubber composition of the present invention.

Hereinafter, an example of a preferred embodiment of the hose of the present invention will be described with reference to FIG. FIG. 1 is a perspective view of each hose layer cut away.
As shown in FIG. 1, the hose 1 includes an inner tube 2, a reinforcing layer 3 disposed adjacent to the outer peripheral side of the inner tube 2, and an outer tube 4 disposed adjacent to the outer peripheral side of the reinforcing layer 3. And have.

  In the hose 1, at least the inner tube 2 is preferably composed of the rubber composition of the present invention. From the viewpoint that the hose 1 is excellent in durability, both the inner tube 2 and the outer tube 4 are the rubber composition of the present invention. It is preferable that it is comprised.

  The reinforcing layer 3 may be formed in a blade shape or may be formed in a spiral shape. Although the material which forms the reinforcement layer 3 is not specifically limited, Metal materials, such as fiber materials, such as a polyamide fiber and a polyester fiber, a hard steel wire (for example, a brass plating wire, a zinc plating wire), etc. are illustrated suitably, However, fiber materials are preferred, and polyamide fibers are more preferred.

  The hose of the present invention is not limited to the above-described three-layer structure. For example, the hose has a five-layer structure in which two reinforcing layers are provided and an interlayer rubber layer is provided between the two reinforcing layers. You may have. It is preferable that the said interlayer rubber layer is comprised with the rubber composition of this invention from a viewpoint that it is excellent in durability of a hose.

  The manufacturing method of the hose of this invention is not specifically limited, A conventionally well-known method can be used. Specifically, for example, after laminating an inner pipe, a reinforcing layer, and an outer pipe in this order on a mandrel, these layers are subjected to press vulcanization, steam under conditions of 140 to 190 ° C. and 30 to 180 minutes. Preferred examples include a method of vulcanization, oven vulcanization (hot air vulcanization), or hot vulcanization for vulcanization and production.

  Since the hose of the present invention uses the rubber composition of the present invention having good characteristics after vulcanization, it is excellent in repeated pressure durability.

  The use, application conditions, and the like of the hose of the present invention are not particularly limited. For example, the hose of the present invention is suitably used for a power steering hose used for piping of a hydraulic power steering.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely according to an Example, this invention is not limited to the following Example.

(Examples 1-1 to 1-6, Comparative Examples 1-1 to 1-10)
The components shown in Table 1 below were blended in the proportions (parts by mass) shown in Table 1 below.
Specifically, when the components shown in Table 1 below, excluding vulcanizing agent 1 or vulcanizing agent 2, were kneaded for 4 minutes with a Banbury mixer (3.4 liters) and reached 140 ° C. A master batch was obtained by discharge. Next, vulcanizing agent 1 or vulcanizing agent 2 was kneaded with the obtained master batch with an open roll to obtain a rubber composition.
The resulting each rubber composition was, by the following method, the lowest Mooney viscosity (Vm), the scorch time (t _5), tensile strength, elongation at break, and hardness was measured. The results are shown in Table 1 below.

<Minimum Mooney Viscosity (Vm), Scorch Time (t ₅ )>
The minimum Mooney viscosity (Vm) is determined based on the “Mooney viscosity test” described in JIS K6300-1: 2001 for each of the obtained rubber compositions using a Mooney viscometer (L-shaped rotor). It is the minimum value of the Mooney viscosity in the Mooney viscosity-time curve in which the rotor was rotated at a test temperature of 125 ° C. for 1 minute.
The scorch time (t ₅ ) represents a time of 5M increase from the minimum Mooney viscosity (Vm), and M represents Mooney units.

<Tensile strength, elongation at break>
The unvulcanized rubber composition was vulcanized for 60 minutes under a surface pressure of 3.0 MPa using a press molding machine at 157 ° 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: 2004, and tensile strength [MPa] and elongation at break [%] were measured at room temperature. It was measured.

<Hardness>
In accordance with JIS K6253: 2006, an unvulcanized rubber composition was vulcanized for 60 minutes under a surface pressure of 3.0 MPa using a press molding machine at 157 ° C. to prepare a 6 mm thick test piece. In accordance with JIS K6253: 2006, hardness (Shore A hardness) was measured using a durometer (type A).

The following components were used as the components in Table 1.
CSM: chlorosulfonated polyethylene (trade name: Hypalon 40, manufactured by DuPont, Mooney viscosity (ML _{1 + 4} , 100 ° C.) 55, chlorine content 35% by mass, sulfur content 1.0% by mass)
ACSM: alkylated chlorosulfonated polyethylene (trade name: Axium HPR-6367, manufactured by DuPont, Mooney viscosity (ML _{1 + 4} , 100 ° C.) 43, chlorine content 27 mass%, sulfur content 1.0 mass%)
Acid acceptor 1: Magnesium oxide (trade name: Kyowa Mag 150, manufactured by Kyowa Chemical Co., Ltd.)
・ Acid acceptor 2: calcium hydroxide (trade name: slaked lime, manufactured by Iriko Industry Co., Ltd.)
・ Carbon black: FEF carbon black (trade name: HTC # 100, manufactured by Nikka Chemical Co., Ltd.)
Processing aid: hydrophilic higher fatty acid ester (trade name: Struktol WB-212, SCHILL & Seillacher GMBH & CO.)
・ Antioxidant: NBC (trade name: NOCRACK NBC, manufactured by Ouchi Shinsei Chemical Co., Ltd.)
Crosslinking initiator: 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline (trade name: Nocrack AW, manufactured by Ouchi Shinsei Chemical Co., Ltd.)
Plasticizer: isononyl trimellitate (trade name: C-9N, manufactured by ADEKA)
・ Vulcanizing agent 1: N, N′-m-phenylenebismaleimide (trade name: HVA-2, manufactured by DuPont)
Vulcanizing agent 2: 1,3-bis (citraconimidomethyl) benzene (trade name: Perkalink 900, manufactured by Flexis)

  From the results shown in Table 1, Examples 1-1 to 1-6 show a scorch time superior to that of Comparative Example 1-1 or 1-6 using a bismaleimide compound as a vulcanizing agent. It was found to exhibit good post-vulcanization properties equal to or better than Examples 1-1 and 1-6.

(Examples 2-1 to 2-6, Comparative Examples 2-1 to 2-10)
Next, the hose was produced using the rubber composition which concerns on an Example or a comparative example.
First, an unvulcanized rubber composition is extruded onto a resin mandrel with a crosshead extruder, and a polyamide fiber is braided with a braiding machine to form a first reinforcing layer, and then an unvulcanized rubber composition is formed. After forming an interlayer rubber layer composed of a product, a polyamide fiber is braided with a braiding machine to form a second reinforcing layer, and an unvulcanized rubber composition is extruded thereon with a crosshead extruder. An outer tube was formed to obtain an unvulcanized hose.
Next, the obtained unvulcanized hose was covered with polymethylpentene resin (trade name: TPX, manufactured by Mitsui Chemicals) and vulcanized with a steam vulcanizer at 157 ° C. for 60 minutes, The polymethylpentene resin that had been coated was peeled off, the mandrel was removed, and a vulcanized hose was obtained. The vulcanized hose thus obtained had an inner diameter of 9.8 mm and an outer diameter of 18 mm.
That is, the hose according to the example and the comparative example has a five-layer structure including an inner tube, two reinforcing layers sandwiching an interlayer rubber layer, and an outer tube. The rubber compositions used for the inner tube, interlayer rubber layer, and outer tube of the hose according to each example are shown in Table 2 below.

<Hose extrusion moldability>
About the hose which concerns on an Example and a comparative example, hose extrusion moldability was evaluated by the hose extrusion external appearance. In addition, when it was a smooth hose appearance, it was evaluated as “◯”, when it was not smooth but there was no defect, it was evaluated as “△”, and when burnt grains were generated on the hose surface, “×” " The results are shown in Table 2 below.
From a practical viewpoint, the hose extrusion moldability is required to be “◯”.

<Repeated pressure durability>
In accordance with JIS K6330-8: 1998, the impact pressure test was performed on the hose according to the example and the comparative example, and repeated pressurization durability was evaluated.
That is, general hydraulic oil (EXXON 1982 ATF) was used, and at 150 ° C., a pressurization cycle was loaded with an upper limit of 400,000 cycles between 0 MPa and 10.3 MPa in a pressurization cycle of 35 cpm. “O” indicates that the hose did not have any abnormalities (for example, leakage at the joint bracket, disconnection of the joint bracket, hose rupture, etc.) after withstanding a pressure cycle of 400,000 times. “×”. In addition, when the hose had an abnormality, the number of pressurization cycles at that time was indicated. The results are shown in Table 2 below.
From a practical viewpoint, the repeated pressure durability is required to be “◯”.

  From the results shown in Table 2, it was found that Examples 2-1 to 2-6 were excellent in both hose extrusion moldability and repeated pressurization durability.

1 Hose 2 Inner pipe 3 Reinforcement layer 4 Outer pipe

Claims (4)

100 parts by weight of a rubber component comprising chlorosulfonated polyethylene and / or alkylated chlorosulfonated polyethylene;
1 to 15 parts by mass of a biscitraconimide compound represented by the following general formula (I);
0.5 to 10 parts by mass of a crosslinking initiator,
Containing a rubber composition.

(In the formula, A is a divalent group selected from the group consisting of an alkylene group, an alkali-ylene group, a cycloalkylene group, an arylene group, an aralkylene group, and an alkenylene group, and R ¹ is a hydrogen atom or a carbon atom having 1 to 18 carbon atoms. And a plurality of R ¹ may be the same or different.)   The rubber composition according to claim 1, wherein the rubber component contains more than 50% by mass of the chlorosulfonated polyethylene and / or the alkylated chlorosulfonated polyethylene. The rubber composition according to claim 1 or 2, wherein the biscitraconimide compound is bis (citraconimidomethyl) benzene represented by the following formula (II).
A hose comprising an inner tube, a reinforcing layer disposed on the outer peripheral side of the inner tube, and an outer tube disposed on the outer peripheral side of the reinforcing layer,
The hose in which the said inner pipe and / or the said outer pipe are comprised with the rubber composition in any one of Claims 1-3.