JP2004018822A - Crosslinked rubber product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crosslinked product that shows no decrease in permanent compression set characteristics when it is used in contact with steam for a long time as well as excellent mechanical properties, and can be favorably used for rubber parts such as hoses, tubes and sealing materials for use in contact with steam. <P>SOLUTION: This crosslinked product is obtained by crosslinking a crosslinkable rubber composition comprising 100 pts.wt. of a nitrile group-containing copolymer rubber (A) having an iodine number of ≤100 and a content of an α, β-ethylenically unsaturated nitrile monomer unit of 10-60 wt.%, 1-30 pts.wt. of an organic peroxide (B) and 0.1-10 pts.wt. of an isocyanurate compound (C). The crosslinked product having a variation of tensile product of ≤120% when it is brought into contact with steam at 150°C for 72 hrs is used. <P>COPYRIGHT: (C)2004,JPO

Description

【００４５】
表１から明らかなように、ＴＡＩＣを使用せずにＴＭＰＴを配合した架橋性ゴム組成物の架橋物（比較例１及び比較例３）は、１５０℃のスチームと７２時間接触させた時の抗張積変化率が１２０％以上であり、この架橋物はスチームと長期に接触させた時の圧縮永久ひずみの増加が大きい。特にＴＭＰＴの配合が多いと（比較例３）、機械的特性（引張り強度、伸び）が劣る。また、酸化亜鉛を配合した架橋性ゴム組成物の架橋物（比較例２）も、１５０℃のスチームと７２時間接触させた時の抗張積変化率が１２０％以上であり、この架橋物はスチームと長期に接触させた時の圧縮永久ひずみの増加が大きく、引張り強度も低下する。
【００４６】
これに対して、１５０℃のスチームと７２時間接触させた時の抗張積変化率が１２０％以下である本発明の架橋物（実施例１及び実施例２）は、スチームと長期に接触させた時でも圧縮永久ひずみが小さく、機械的特性（引張り強度、伸び）にも優れていることが確認できる。
【００４７】
【発明の効果】
本発明によれば、機械的特性に優れ、スチームと長期に接触させて使用しても圧縮永久ひずみ特性が低下しない架橋物が提供される。この架橋物は、スチームと接触させて使用するホース、チューブ、シール材などのゴム部品に好適に使用することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a crosslinked product obtained by crosslinking a crosslinkable nitrile group-containing copolymer rubber composition, and more particularly to a crosslinked product suitable as a sealing material.
[0002]
[Prior art]
Hydrogenated NBR obtained by hydrogenating acrylonitrile-butadiene copolymer rubber (NBR) is known as a rubber material having excellent heat resistance and oil resistance. Hydrogenated NBR is used as a material for rubber parts for automobiles, such as hoses and tubes, as well as belts, utilizing this heat resistance and oil resistance.
In addition, hydrogenated NBR has excellent heat resistance and oil resistance even under high pressure conditions. Therefore, sealing materials such as O-rings, packings and gaskets that require pressure resistance in addition to heat resistance and oil resistance are required. Also widely used as.
[0003]
Many of such sealing materials are used in a state of being in contact with boiling water or steam for a long time, and improvement of steam resistance is one of the important technical issues of hydrogenated NBR.
[0004]
For example, Japanese Patent Application Laid-Open No. 60-86135 discloses a crosslinkable rubber composition comprising a nitrile group-containing copolymer rubber having an iodine value of 120 or less and an organic peroxide crosslinkable system, based on 100 parts by weight of the rubber. It has been reported that a product obtained by blending 8 to 30 parts by weight of a crosslinking accelerator and having excellent crosslinking resistance has excellent steam resistance.
[0005]
However, when a relatively large amount of a crosslinking accelerator is blended with hydrogenated NBR and crosslinked, generally, the mechanical properties of the obtained crosslinked product tend to change significantly, and sealing materials, hoses and tubes are generally used. In some cases, it was not possible to obtain suitable physical properties.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a crosslinked product of hydrogenated NBR which has excellent mechanical properties and does not deteriorate in compression set even when used in contact with steam or boiling water for a long period of time.
[0007]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, a rubber crosslinked product obtained by crosslinking a hydrogenated nitrile group-containing copolymer rubber with an organic peroxide and an isocyanuric acid ester compound, under specific conditions It was found that the tensile product change rate was small, the mechanical properties were excellent, and the compression set characteristics did not decrease even if it was brought into contact with steam for a long period of time, and based on this finding, the present invention was completed. Was.
[0008]
Thus, according to the present invention,
1. (1) A nitrile group-containing copolymer rubber (A) having an iodine value of 100 or less having an α, β-ethylenically unsaturated nitrile monomer unit content of 10 to 60% by weight, and 100 parts by weight of the rubber (A) A crosslinkable rubber composition containing 1 to 30 parts by weight of an organic peroxide (B) and 0.1 to 10 parts by weight of an isocyanuric acid ester compound (C), and
(2) a rubber crosslinked product, wherein the rate of change in tensile product when contacted with steam at 150 ° C. for 72 hours is 120% or less;
2. (1) A nitrile group-containing copolymer rubber (A) having an iodine value of 100 or less having an α, β-ethylenically unsaturated nitrile monomer unit content of 10 to 60% by weight, and 100 parts by weight of the rubber (A) A crosslinkable rubber composition containing 1 to 30 parts by weight of an organic peroxide (B) and 0.1 to 10 parts by weight of an isocyanuric acid ester compound (C) and containing substantially no zinc oxide A rubber crosslinked product obtained by crosslinking
3. The crosslinked product according to the above 1 or 2, wherein the isocyanuric acid ester compound (C) is triallyl isocyanuric acid ester,
4. The crosslinked product according to any one of the above 1 to 3, which is a sealing material,
Are provided respectively.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The crosslinked product of the present invention comprises (1) a nitrile group-containing copolymer rubber (A) having an iodine value of 100 or less (A) having an α, β-ethylenically unsaturated nitrile monomer unit content of 10 to 60% by weight. , Nitrile group-containing copolymer rubber (A) may be abbreviated as 100 parts by weight), 1 to 30 parts by weight of organic peroxide (B) and 0.1 to 10 parts by weight of isocyanurate compound (C). It is formed by crosslinking a crosslinkable rubber composition containing parts by weight, and
(2) The rate of change of the tensile product when exposed to steam at 150 ° C. for 72 hours is 120% or less.
[0010]
The nitrile group-containing copolymer rubber (A) used in the present invention is a rubber obtained by copolymerizing an α, β-ethylenically unsaturated nitrile monomer and another monomer by a known method.
[0011]
Examples of the α, β-ethylenically unsaturated nitrile monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile and the like, with acrylonitrile being preferred. The content of the α, β-ethylenically unsaturated nitrile monomer unit in the nitrile group-containing copolymer rubber (A) is 10 to 60% by weight, preferably 12 to 55% by weight, more preferably 15 to 50% by weight. %. If the content of the α, β-ethylenically unsaturated nitrile monomer unit in the nitrile group-containing copolymer rubber is too small, the oil resistance of the crosslinked product may be poor, and if it is too large, the cold resistance may be poor. is there.
[0012]
Examples of the monomer that can be copolymerized with the α, β-ethylenically unsaturated nitrile monomer include a conjugated diene monomer, a non-conjugated diene monomer, and an α-olefin.
Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene, and 1,3-butadiene is preferable. The non-conjugated diene monomer preferably has 5 to 12 carbon atoms, and examples thereof include 1,4-pentadiene, 1,4-hexadiene, vinylnorbornene, and dicyclopentadiene. As the α-olefin, those having 2 to 12 carbon atoms are preferable, and examples thereof include ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene.
[0013]
Further, the nitrile group-containing copolymer rubber (A) includes, in addition to the above-mentioned monomers, an aromatic vinyl monomer, a fluoroolefin monomer, an α, β-ethylenically unsaturated carboxylic acid-based monomer, and the like. It may be obtained by copolymerization within a range that does not impair the object of the present invention. In addition, these monomers may be copolymerizable antioxidants. The content of these monomer units in the nitrile group-containing copolymer rubber (A) is preferably from 0 to 30% by weight, more preferably from 0 to 25% by weight.
[0014]
Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinylpyridine and the like. Examples of the fluoroolefin monomer include fluoroethyl vinyl ether, fluoropropyl vinyl ether, o-trifluoromethylstyrene, vinyl pentafluorobenzoate, difluoroethylene, tetrafluoroethylene, and the like. α, β-ethylenically unsaturated carboxylic acid monomers include α, β-ethylenically unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; α, β such as ethyl acrylate, butyl acrylate and methoxyethyl acrylate -Ethylenically unsaturated monocarboxylic acid esters; α, β-ethylenically unsaturated polycarboxylic acids such as itaconic acid, fumaric acid and maleic acid; α, β-ethylenically unsaturated acids such as itaconic anhydride and maleic anhydride Polycarboxylic acid anhydrides; α, β-ethylenically unsaturated polycarboxylic acid esters such as monobutylitaconic acid and dibutylitaconic acid; and the like. Examples of the copolymerizable antioxidant include N- (4-anilinophenyl) acrylamide, N- (4-anilinophenyl) methacrylamide, N- (4-anilinophenyl) cinnamamide, and N- (4 -Anilinophenyl) crotonamide, N-phenyl-4- (3-vinylbenzyloxy) aniline, N-phenyl-4- (4-vinylbenzyloxy) aniline and the like.
[0015]
The iodine value of the nitrile group-containing copolymer rubber (A) is 100 or less, preferably 50 or less, more preferably 20 or less. If the iodine value is too large, heat resistance is poor.
[0016]
When an α, β-ethylenically unsaturated nitrile monomer and a conjugated diene monomer are copolymerized, the iodine value may exceed 100. In this case, the carbon-carbon unsaturated bond of the copolymer rubber (A) is hydrogenated by a known method so that the iodine value becomes 100 or less. The method of hydrogenation is not particularly limited, and may be a known method.
[0017]
The Mooney viscosity ML _{1 + 4} (100 ° C.) of the nitrile group-containing copolymer rubber (A) is preferably 10 to 300, more preferably 20 to 250, and particularly preferably 30 to 200. If the Mooney viscosity is too low, the mechanical properties of the crosslinked product may be poor, and if it is too high, processability may be poor.
[0018]
The organic peroxide (B) used in the present invention is not particularly limited as long as it is used as a rubber crosslinking agent, and a conventionally known organic peroxide crosslinking agent can be used.
[0019]
Examples of the organic peroxide (B) include dialkyl peroxide, diacyl peroxide, peroxyester, and the like, and dialkyl peroxide is preferable. Examples of the dialkyl peroxide include dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) -3-hexyne, and 2,5-dimethyl- Examples thereof include 2,5-di (t-butylperoxy) hexane and 1,3-bis (t-butylperoxyisopropyl) benzene. Examples of the diacyl peroxide include benzoyl peroxide and isobutyryl peroxide. Examples of the peroxyester include 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxyisopropyl carbonate, and the like.
The compounding amount of the organic peroxide (B) to the nitrile group-containing copolymer rubber (A) is 1 to 30 parts by weight, preferably 1.5 to 20 parts by weight, more preferably 1.5 to 20 parts by weight, per 100 parts by weight of the rubber (A). It is 2 to 10 parts by weight. If the amount of the organic peroxide (B) is too small, the crosslink density decreases and the compression set of the crosslinked product increases. If the amount of the organic peroxide (B) is too large, the rubber elasticity of the crosslinked product may be insufficient.
[0020]
The isocyanuric acid ester compound (C) used in the present invention is a compound having a structure in which at least one hydrogen bonded to the nitrogen atom of isocyanuric acid is replaced with a hydrocarbon group, and isocyanuric acid monoester, diester, and triester are In the present invention, diesters or triesters are preferred, and triesters are most preferred. Examples of the hydrocarbon group that can be replaced with hydrogen include an alkyl group and an alkenyl group. An alkenyl group is preferable, and among the alkenyl groups, an allyl group is most preferable.
Specific examples of such an isocyanuric acid ester compound (C) include isocyanuric acid triesters such as triallyl isocyanurate (TAIC) and trimethallyl isocyanurate; isocyanuric acid diesters such as diallyl isocyanurate and dimethallyl isocyanurate; Is mentioned. Of these, isocyanuric acid triesters are preferred, and triallyl isocyanurate is most preferred.
The compounding amount of the isocyanuric acid ester compound (C) with respect to the nitrile group-containing copolymer rubber (A) is 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, per 100 parts by weight of the rubber (A). Preferably it is 1 to 6 parts by weight. If the compounding amount of the isocyanuric acid ester compound (C) is too small, the compression set characteristic at the time of long-term steam contact is reduced, while if too large, the mechanical properties such as elongation of the crosslinked product are reduced.
[0021]
The crosslinkable rubber composition used in the present invention contains a nitrile group-containing copolymer rubber (A), an organic peroxide (B) and an isocyanurate compound (C).
[0022]
The crosslinkable rubber composition may be blended with a polyfunctional monomer such as bismaleimide, polyacrylate or quinonedioxime as a crosslinking assistant for the organic peroxide (B).
Examples of the bismaleimide include phenylene bismaleimide and naphthene bismaleimide. In the present invention, phenylenebismaleimide is most preferred, and N, N'-m-phenylenebismaleimide is most preferred. As the polyvalent acrylate, trimethylolpropane trimethacrylate and the like are preferable. Examples of the quinone dioxime include p-benzoquinone dioxime, 4,4′-diacetylbenzoquinone dioxime, 4,4′-dipropionylbenzoquinone dioxime, and 4,4′-dibenzoylbenzoquinone dioxime. Among them, 4,4′-dibenzoylbenzoquinonedioxime is most preferred.
These crosslinking aids may be dispersed in and blended with clay, calcium carbonate, silica and the like. The type and amount of these crosslinking assistants are not particularly limited, and may be determined according to the use of the crosslinked product, required performance, the type of organic peroxide, and the like.
[0023]
As the crosslinking agent, a sulfur-based crosslinking agent may be used in combination with the organic peroxide (B). Examples of the sulfur-based crosslinking agent include sulfur such as powdered sulfur and precipitated sulfur; and organic sulfur compounds such as 4,4′-dithiomorpholine, tetramethylthiuram disulfide, tetraethylthiuram disulfide, and high molecular polysulfide.
[0024]
When a sulfur-based cross-linking agent is used in combination, generally, a cross-linking accelerator such as a guanidine compound, a thiuram compound, a dithiocarbamate, or a sulfenamide, and a cross-linking auxiliary such as zinc oxide can be used. Preferably, the crosslinkable rubber composition does not contain zinc oxide. Even when zinc oxide is contained, its content is less than 5 parts by weight, preferably 3 parts by weight, per 100 parts by weight of the nitrile group-containing copolymer rubber. It is less than 1 part by weight, more preferably less than 1 part by weight. If the content of zinc oxide is too large, the rate of change in elongation at the time of steam contact of the crosslinked product increases.
[0025]
The crosslinkable rubber composition used in the present invention is a compounding agent generally used for rubber, for example, a reinforcing agent such as carbon black, silica, and short fiber; a filler such as calcium carbonate, clay, talc, and calcium silicate. A plasticizer; a pigment; an antioxidant; a tackifier; a processing aid; an anti-scorch agent; Further, the crosslinkable rubber composition of the present invention may contain a rubber or resin other than the nitrile group-containing copolymer rubber (A) within a range that does not substantially impair the effects of the present invention.
[0026]
The method for preparing the crosslinkable rubber composition used in the present invention is not particularly limited, and may be a general method for preparing a crosslinkable rubber composition. For example, an appropriate mixing method such as roll mixing, Banbury mixing, screw mixing, and solution mixing can be adopted. The order of blending is not particularly limited, but after sufficiently mixing components that are not easily reacted or decomposed by heat, a crosslinking agent or the like that is easily reacted or decomposed by heat may be mixed in a short time at a temperature at which no reaction or decomposition occurs. .
[0027]
The method for molding the crosslinkable rubber composition is not particularly limited. Any method such as compression molding, injection molding, transfer molding, or extrusion molding can be used. The crosslinking method may be selected according to the shape of the crosslinked product, and may be any of a method of performing molding and crosslinking at the same time or a method of performing crosslinking after molding.
[0028]
The crosslinked product of the present invention is obtained by crosslinking the above crosslinkable rubber composition. The method of crosslinking the crosslinkable rubber composition may be such that the rubber composition is heated to a predetermined temperature or higher. Generally, heating is performed after molding by the above method, or heating is performed simultaneously with molding.
[0029]
The crosslinking temperature is preferably from 100 to 200C, more preferably from 130 to 195C, particularly preferably from 140 to 190C. If the temperature is too low, the crosslinking time may be required for a long time or the crosslinking density may be low. If the temperature is too high, molding failure may occur. The crosslinking time varies depending on the crosslinking method, crosslinking temperature, shape, etc., but is preferably 1 minute to 4 hours from the viewpoint of crosslinking density and production efficiency.
[0030]
A heating method for crosslinking may be appropriately selected from methods used for rubber crosslinking such as press heating, steam heating, oven heating, and hot air heating.
[0031]
Depending on the shape and size of the crosslinked product, the inside may not be crosslinked even if the surface is crosslinked. In such a case, after crosslinking as described above, secondary crosslinking for maintaining a high temperature state may be performed.
[0032]
The crosslinked product of the present invention has a tensile product change rate of 120% or less, and preferably 110% or less when it is brought into contact with steam at 150 ° C. for 72 hours. Tensile product is the product of the tensile strength and elongation of rubber, and is one of the physical properties used for evaluating the physical properties of rubber in some test methods specified in JIS, and is required for breaking rubber. It is a physical property value representing energy. The rate of change of the tensile product when contacted with steam at 150 ° C. for 72 hours, that is, the crosslinked product in which the ratio of the tensile product after contact with steam for 72 hours to the tensile product before steam contact exceeds 120% is as follows: The compression set characteristic is degraded during long-term contact with steam.
The crosslinked product of the present invention has excellent mechanical properties and a small compression set upon long-term steam contact, so that it can be used for various applications. Its application is not particularly limited, for example, including industrial products such as seals, rubber belts, rubber rolls, rubber hoses and parts thereof, oil wells, packers used in oil wells, gas wells, etc. it can. Examples of the seal include movement seals for rotation, swinging, reciprocating movement, and the like, and fixing seals. Examples of the motion seal include an oil seal, a piston seal, and a mechanical seal, and examples of the fixing seal include an O-ring and various gaskets. Examples of the rubber belt include a flat belt, a V belt, a V-ribbed belt, a round belt, a square belt, and a toothed belt. Examples of rubber rolls include rolls that are parts of OA equipment such as printing equipment and copying equipment; rolls for fiber processing such as drawing rolls for spinning and draft rolls for spinning; and rolls for iron making such as bridle rolls, snubber rolls, and steering rolls. No. Examples of the rubber hose include a single tube rubber hose, a multilayer rubber hose, a braided reinforcing hose, and a cloth-wound reinforcing hose. Since the crosslinked product of the present invention has low mechanical properties and low compression set, it is particularly suitable for use in seals and rubber belts, and is most suitable as a sealant.
[0033]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples. Parts and percentages are by weight unless otherwise indicated. In addition, the evaluation method is as follows.
[0034]
(1) Mooney viscosity The Mooney viscosity of the crosslinkable rubber composition was measured at 100 ° C according to JIS K6300.
[0035]
(2) Tensile strength and elongation The crosslinked rubber composition having been adjusted was crosslinked at 170 ° C. under a pressure of 10 MPa for 15 minutes, and then subjected to secondary crosslinking at 150 ° C. for 4 hours to obtain a sheet having a thickness of 2 mm. This sheet was punched out using a No. 3 dumbbell to prepare a test piece. Using these test pieces, the tensile strength and elongation of the crosslinked product were measured as mechanical properties according to JIS K6251.
[0036]
(3) Tensile product change rate The tensile product change rate was determined by contacting a test piece similar to that prepared in the above (3) with steam at 150 ° C. for 72 hours, and then applying a tensile strength in the same manner as in (3). The tensile strength and elongation were measured, and the product of the tensile strength and the elongation was calculated, and the ratio of this and (3) to the product of the tensile strength and the elongation was calculated.
[0037]
(4) Compression set at the time of steam contact According to JIS K 6254, the crosslinkable rubber composition was crosslinked at 170 ° C for 15 minutes under a pressure of 10 MPa, and then subjected to secondary crosslinking at 150 ° C for 4 hours to obtain a cylindrical test piece. Got. Using this test piece, the compression set was measured over time when it was brought into contact with steam at 150 ° C. in a 25% compressed state.
[0038]
Example 1
100 parts of nitrile group-containing copolymer rubber A (Zetpol 2000, manufactured by Zeon Corporation, hydrogenated acrylonitrile-butadiene copolymer rubber, acrylonitrile unit content 36%, iodine value 4, Mooney viscosity ML _{1 + 4} , (100 ° C.) 83), After kneading 45 parts of carbon black (classified by ASTM D1765; N762) and 1 part of a diphenylamine-based antioxidant in a Banbury at 50 ° C., 1,3-bis (t-butylperoxyisopropyl) benzene (organic peroxide) Product) and 2 parts of triallyl isocyanurate (TAIC) were added and kneaded at 40 ° C. with an open roll to prepare a crosslinkable rubber composition.
[0039]
This crosslinkable rubber composition was crosslinked under the above conditions to obtain a crosslinked product. When the crosslinked product was brought into contact with steam at 150 ° C. for 72 hours, the tensile strength change rate was 103%. The tensile strength, elongation, and compression set at the time of steam contact of the crosslinked product were evaluated. Table 1 shows the results.
[0040]
Example 2
A crosslinkable rubber composition was produced in the same manner as in Example 1 except that the amount of TAIC was changed to 8 parts, and the composition was crosslinked to obtain a crosslinked product. When the crosslinked product was brought into contact with steam at 150 ° C. for 72 hours, the tensile product change rate was 102%. The tensile strength, elongation, and compression set at the time of steam contact of the crosslinked product were evaluated. Table 1 shows the results.
[0041]
Comparative Example 1
A crosslinkable rubber composition was produced in the same manner as in Example 1 except that 2 parts of trimethylolpropane triacrylate (TMPT) was used instead of TAIC, and was crosslinked to obtain a crosslinked product. When the crosslinked product was brought into contact with steam at 150 ° C. for 72 hours, the tensile product change rate was 129%. The tensile strength, elongation, and compression set at the time of steam contact of the crosslinked product were evaluated. Table 1 shows the results.
[0042]
Comparative Example 2
Further, a crosslinkable rubber composition was produced in the same manner as in Example 1 except that 5 parts of zinc oxide was added, and crosslinked to obtain a crosslinked product. When the crosslinked product was brought into contact with steam at 150 ° C. for 72 hours, the tensile product change rate was 128%. The tensile strength, elongation, and compression set at the time of steam contact of the crosslinked product were evaluated. Table 1 shows the results.
[0043]
Comparative Example 3
A crosslinkable rubber composition was produced in the same manner as in Comparative Example 1 except that the amount of TMPT was changed to 15 parts, and crosslinked to obtain a crosslinked product. When the crosslinked product was brought into contact with steam at 150 ° C. for 72 hours, the tensile product change rate was 130%. The tensile strength, elongation, and compression set at the time of steam contact of the crosslinked product were evaluated. Table 1 shows the results.
[0044]
[Table 1]

[0045]
As is clear from Table 1, the crosslinked products of the crosslinkable rubber composition containing TMPT without using TAIC (Comparative Example 1 and Comparative Example 3) exhibited an anti-shrinkage property when contacted with steam at 150 ° C. for 72 hours. The rate of change in tonicity is 120% or more, and this crosslinked product has a large increase in compression set when it is brought into contact with steam for a long time. In particular, when the content of TMPT is large (Comparative Example 3), the mechanical properties (tensile strength, elongation) are inferior. The crosslinked product of the crosslinkable rubber composition containing zinc oxide (Comparative Example 2) also had a tensile product change rate of 120% or more when contacted with steam at 150 ° C. for 72 hours. The increase in compression set upon long-term contact with steam is large, and the tensile strength is also reduced.
[0046]
On the other hand, the crosslinked product of the present invention (Examples 1 and 2) having a tensile product change rate of 120% or less when contacted with steam at 150 ° C. for 72 hours was brought into contact with steam for a long time. It can be confirmed that the compression set is small and the mechanical properties (tensile strength, elongation) are excellent even when the test is carried out.
[0047]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the crosslinked material which is excellent in mechanical characteristics and which does not reduce a compression set characteristic even if it is made to contact with steam for a long period of time is provided. This crosslinked product can be suitably used for rubber parts such as hoses, tubes, and sealing materials used in contact with steam.

Claims (4)

(1) A nitrile group-containing copolymer rubber (A) having an iodine value of 100 or less having an α, β-ethylenically unsaturated nitrile monomer unit content of 10 to 60% by weight, and 100 parts by weight of the rubber (A) A crosslinkable rubber composition containing 1 to 30 parts by weight of an organic peroxide (B) and 0.1 to 10 parts by weight of an isocyanuric acid ester compound (C), and
(2) A crosslinked rubber product having a change rate of tensile product of 120% or less when contacted with steam at 150 ° C. for 72 hours. (1) A nitrile group-containing copolymer rubber (A) having an iodine value of 100 or less having an α, β-ethylenically unsaturated nitrile monomer unit content of 10 to 60% by weight, and 100 parts by weight of the rubber (A) A crosslinkable rubber composition containing 1 to 30 parts by weight of an organic peroxide (B) and 0.1 to 10 parts by weight of an isocyanuric acid ester compound (C), and containing substantially no zinc oxide A rubber cross-linked product obtained by cross-linking 3. The crosslinked product according to claim 1, wherein the isocyanuric acid ester compound (C) is triallyl isocyanuric acid ester. 4. The crosslinked product according to claim 1, which is a sealing material.