JP2011012132A - Nitrile rubber composition, crosslinkable rubber composition, and rubber crosslinked material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nitrile rubber composition giving a nitrile rubber crosslinked material having good oil resistance and excellent gasoline permeation resistance and cold resistance, and to provide a crosslinked material.SOLUTION: The nitrile rubber composition comprises 100 pts.wt of a polymer component (A) having the following component and 0.1 to 200 pts.wt of a plasticizer (B) having an SP value ranging from 8.0 to 10.2 (cal/cm)by Hoy method. A crosslinkable rubber composition and a crosslinked material are also provided. The polymer component (A) comprises: 40 to 95 wt.% of a nitrile rubber (a) containing 36 to 54 wt.% of α,β-ethylenically unsaturated nitrile monomer units and conjugated diene monomer units which may be at least partially hydrogenated, and having less than 20 wt.% of a methylethylketone-insoluble content; and 60 to 5 wt.% of a polymer (b) containing 50 to 100 wt.% of vinyl monomer units comprising aromatic vinyl monomer units or α,β-ethylenically unsaturated nitrile monomer units and 50 to 0 wt.% of conjugated diene monomer units which may be at least partially hydrogenated, and having 20 wt.% or more of a methylethylketone-insoluble content.

Description

  The present invention relates to a nitrile rubber composition and a crosslinkable rubber composition that give a crosslinked nitrile rubber excellent in gasoline permeation resistance and cold resistance, and the crosslinked product.

  Conventionally, a rubber (nitrile rubber) containing an α, β-ethylenically unsaturated nitrile monomer unit and a conjugated diene monomer unit has been known as a rubber excellent in oil resistance, and is mainly a fuel hose. It is used as a material for rubber products around various oils, such as industrial parts and automobiles, such as fuel gaskets, fuel packings, oil seals and inlet hoses.

An excellent requirement for oil resistance and cold resistance is an important requirement for this application, but recently, efforts to reduce the transpiration of fuels such as gasoline into the atmosphere due to increasing global environmental protection activities. Progressing. For example, in Japan and Europe, NO _X emissions is restricted, has been required to reduce the fuel transpiration Along with this, therefore, fuel hoses, seals, it is required even lower gasoline permeability in applications such as packing It has been.

  Under such circumstances, Patent Document 1 proposes to disperse a layered silicate that swells in an aqueous medium such as bentonite in rubber latex, and Patent Document 2 discloses an aqueous montmorillonite that is a layered clay mineral in rubber latex. It has been proposed to stir and mix the suspension and a surfactant such as pyrophosphate compound at high speed to improve gas barrier properties. However, these methods have insufficient gasoline permeation resistance. there were.

  Patent Document 3 is a nitrile rubber of ultra-high nitrile having a nitrile content of 55 to 80% by weight, having a glass transition temperature of 15 to 30 ° C. and an extrapolation end temperature of the glass transition of 70 ° C. or less. Has proposed. This rubber is excellent in mechanical strength, oil resistance and weather resistance, and has particularly high gas permeation resistance. As the gas permeation resistance, “Fuel C (equal volume ratio of isooctane and toluene is included. ) "Was small, it was expected to reduce gasoline permeability, but cold resistance was not sufficient.

  Therefore, in Patent Document 4, by adding a plasticizer and magnesium silicate having an aspect ratio of 2 to 100 to a nitrile rubber of ultra high nitrile having a nitrile content of 55 to 80% by weight, gasoline permeability is further improved. Small nitrile rubber compositions have been proposed. However, even in this Patent Document 4, it has not been possible to realize cold resistance that is satisfactory in use.

JP 2004-51748 A JP 2006-70137 A JP 2002-206011 A JP 2007-224161 A

  An object of the present invention is to provide a nitrile rubber composition and a crosslinkable rubber composition that give a crosslinked nitrile rubber excellent in gasoline permeation resistance and cold resistance, and a crosslinked product thereof.

  As a result of intensive research to solve the above problems, the present inventors have found that a nitrile rubber having a predetermined amount of an α, β-ethylenically unsaturated nitrile monomer unit and a methylethylketone insoluble content of 20% by weight or more. It has been found that the above object can be achieved by a nitrile rubber composition comprising a polymer component containing a specific copolymer and a specific plasticizer, and the present invention has been completed.

That is, according to the present invention,
an α, β-ethylenically unsaturated nitrile monomer unit and a conjugated diene monomer unit which may be at least partially hydrogenated, the α, β-ethylenically unsaturated nitrile monomer unit Nitrile rubber (a) having a content of 36 to 54% by weight and an insoluble content of methyl ethyl ketone of less than 20% by weight, and 40 to 95% by weight, and
At least a part of at least one vinyl monomer unit selected from the group consisting of an aromatic vinyl monomer unit and an α, β-ethylenically unsaturated nitrile monomer unit is at least partially hydrogenated. A polymer component (A) containing 50 to 0% by weight of a conjugated diene monomer unit, and 60 to 5% by weight of a polymer (b) having an insoluble content of methyl ethyl ketone of 20% by weight or more; And
The SP value by the HOY method is in the range of 8.0 to 10.2 (cal / cm ³ ) ^1/2 at a ratio of 0.1 to 200 parts by weight with respect to 100 parts by weight of the polymer component (A). Plasticizer (B);
The nitrile rubber composition characterized by containing is provided.

  The nitrile rubber composition of the present invention is a nitrile rubber composition in which at least one of the nitrile rubber (a) and the polymer (b) further contains 0 to 30% by weight of a cationic monomer unit. It is preferable.

  In the nitrile rubber composition of the present invention, at least one of the nitrile rubber (a) and the polymer (b) is obtained by hydrogenating a carbon-carbon unsaturated bond of a conjugated diene monomer unit. A nitrile rubber composition is preferred.

  Further, according to the present invention, at least one thermoplastic resin selected from the group consisting of polyvinyl chloride resin and acrylic resin is 10 to 100 parts by weight with respect to 100 parts by weight of the polymer component (A). A nitrile rubber composition is provided.

  Furthermore, according to this invention, the nitrile rubber composition which contains the inorganic filler whose aspect ratio is 30-2,000 in the ratio of 1-100 weight part with respect to 100 weight part of said polymer components (A). Things are provided.

  The present invention also provides a crosslinkable nitrile rubber composition obtained by adding a crosslinking agent to the nitrile rubber composition described above, and a rubber crosslinked product obtained by crosslinking the crosslinkable nitrile rubber composition. The

  ADVANTAGE OF THE INVENTION According to this invention, the nitrile rubber composition and crosslinkable nitrile rubber composition which give the nitrile rubber crosslinked material excellent in gasoline permeability resistance and cold resistance, and the rubber crosslinked material can be provided. As a result, the rubber cross-linked product obtained from the nitrile rubber composition of the present invention is excellent in gasoline permeation resistance and cold resistance in addition to the original characteristics of nitrile rubber having good oil resistance.

The nitrile rubber composition of the present invention is
an α, β-ethylenically unsaturated nitrile monomer unit and a conjugated diene monomer unit which may be at least partially hydrogenated, the α, β-ethylenically unsaturated nitrile monomer unit Nitrile rubber (a) having a content of 36 to 54% by weight and an insoluble content of methyl ethyl ketone of less than 20% by weight, and 40 to 95% by weight, and
At least a part of at least one vinyl monomer unit selected from the group consisting of an aromatic vinyl monomer unit and an α, β-ethylenically unsaturated nitrile monomer unit is at least partially hydrogenated. A polymer component (A) containing 60 to 5% by weight of a polymer (b) containing 50 to 0% by weight of a conjugated diene monomer unit and having an insoluble content of methyl ethyl ketone of 20% by weight or more; ,
The SP value by the HOY method is in the range of 8.0 to 10.2 (cal / cm ³ ) ^1/2 at a ratio of 0.1 to 200 parts by weight with respect to 100 parts by weight of the polymer component (A). Plasticizer (B);
It is a nitrile rubber composition characterized by containing.

Nitrile rubber (a)
The nitrile rubber (a) used in the present invention contains an α, β-ethylenically unsaturated nitrile monomer unit and a conjugated diene monomer unit which may be at least partially hydrogenated. The content ratio of the β-ethylenically unsaturated nitrile monomer unit is 36 to 54% by weight.

  The α, β-ethylenically unsaturated nitrile monomer forming the α, β-ethylenically unsaturated nitrile monomer unit is particularly limited as long as it is an α, β-ethylenically unsaturated compound having a nitrile group. Although not, for example, acrylonitrile; α-halogenoacrylonitrile such as α-chloroacrylonitrile and α-bromoacrylonitrile; α-alkylacrylonitrile such as methacrylonitrile; Among these, acrylonitrile and methacrylonitrile are preferable, and acrylonitrile is particularly preferable. These can be used individually by 1 type or in combination of multiple types.

  The content ratio of the α, β-ethylenically unsaturated nitrile monomer unit in the nitrile rubber (a) is 36 to 54% by weight, preferably 39 to 52% by weight, based on the total monomer units. Preferably it is 41-51 weight%. When the content ratio of the α, β-ethylenically unsaturated nitrile monomer unit is too low, the oil resistance of the resulting rubber cross-linked product is deteriorated and the gasoline permeability is increased. On the other hand, if the content is too high, the resulting rubber cross-linked product has a high embrittlement temperature and is inferior in cold resistance.

  The nitrile rubber (a) used in the present invention contains a conjugated diene monomer unit so that the obtained rubber cross-linked product has rubber elasticity.

  The conjugated diene monomer forming the conjugated diene monomer unit is preferably a conjugated diene monomer having 4 to 6 carbon atoms, such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3. -Butadiene, 1,3-pentadiene and the like. Of these, 1,3-butadiene is preferred. These can be used individually by 1 type or in combination of multiple types.

  The content ratio of the conjugated diene monomer unit in the nitrile rubber (a) is preferably 46 to 64% by weight, more preferably 47.7 to 61% by weight, and particularly preferably 48.60% by weight with respect to the total monomer units. 5 to 59% by weight.

  When the content rate of a conjugated diene monomer unit is too low, there exists a possibility that the rubber elasticity of the rubber crosslinked material obtained may fall. On the other hand, if the content ratio of the conjugated diene monomer unit is too large, the gasoline permeation resistance of the resulting rubber cross-linked product may be deteriorated.

  The nitrile rubber (a) used in the present invention contains a cationic monomer unit as an α, β-ethylenically unsaturated monomer unit other than the α, β-ethylenically unsaturated nitrile monomer unit. It is preferable to do. The cationic monomer unit means at least one monomer unit selected from the group consisting of a cation-containing monomer unit and a monomer unit capable of forming a cation.

  The cation-containing monomer that forms the cationic monomer unit may be any monomer that forms a monomer unit that is positively charged when the resulting polymer contacts water or an aqueous acid solution. There is no particular limitation. Examples of such cation-containing monomers include monomers containing a quaternary ammonium base. In addition, as a monomer that forms a monomer unit capable of forming a cation, an ammonium salt (for example, amine hydrochloride or amine sulfate) is brought into contact with an aqueous acid solution such as hydrochloric acid and sulfuric acid such as a tertiary amino group. And a monomer having a precursor part (substituent) that forms a cation such as a salt).

  Specific examples of the cation-containing monomer include (meth) acryloyloxytrimethylammonium chloride, (meth) acryloyloxyhydroxypropyltrimethylammonium chloride, (meth) acryloyloxytriethylammonium chloride, (meth) acryloyloxydimethylbenzylammonium chloride, (Meth) acrylic acid ester monomer containing a group having a quaternary ammonium salt such as (meth) acryloyloxytrimethylammonium methyl sulfate; (meth) acrylamidopropyltrimethylammonium chloride, (meth) acrylamidopropyldimethylbenzylammonium chloride And (meth) acrylamide monomers containing a group having a quaternary ammonium salt such as

  Specific examples of the monomer that forms a monomer unit capable of forming a cation include vinyl group-containing cyclic tertiary amine monomers such as 2-vinylpyridine and 4-vinylpyridine; dimethyl (meth) acrylate Tertiary amino group-containing (meth) acrylic acid ester monomer such as aminoethyl; tertiary amino group-containing (meth) acrylamide single amount such as (meth) acrylamide dimethylaminoethyl and N, N-dimethylaminopropyl acrylamide N- (4-anilinophenyl) acrylamide, N- (4-anilinophenyl) methacrylamide, N- (4-anilinophenyl) cinnamamide, N- (4-anilinophenyl) crotonamide, N- Phenyl-4- (3-vinylbenzyloxy) aniline, N-phenyl-4- (4-vinylbenzyloxy) aniline, etc. And the like. These can be used individually by 1 type or in combination of multiple types.

  Among the above monomers, the effects of the present invention become more prominent, so that a vinyl group-containing cyclic tertiary amine monomer, a tertiary amino group-containing (meth) acrylate monomer, and Tertiary amino group-containing (meth) acrylamide monomers are preferred, vinyl group-containing cyclic tertiary amine monomers and tertiary amino group-containing acrylamide monomers are more preferred, vinyl group-containing cyclic tertiary amine monomers More preferred is a monomer, of which vinyl group-containing pyridines are particularly preferred, and 2-vinylpyridine is most preferred.

  The content ratio of the cationic monomer unit is preferably 0 to 30% by weight, more preferably 0.1 to 18% by weight, still more preferably 0.3 to 13% by weight, based on all monomer units. Particularly preferred is 0.5 to 10% by weight. By containing a cationic monomer unit, the obtained rubber cross-linked product becomes more excellent in gasoline permeation resistance and cold resistance.

  Further, the nitrile rubber (a) used in the present invention is a monomer other than the above α, β-ethylenically unsaturated nitrile monomer unit, conjugated diene monomer unit, and cationic monomer unit. It may contain a unit of another monomer copolymerizable with the monomer forming the body unit. The content ratio of such other monomer units is preferably 30% by weight or less, more preferably 20% by weight or less, and still more preferably 10% by weight or less based on the total monomer units.

  Examples of such other copolymerizable monomers include fluorine containing fluoroethyl vinyl ether, fluoropropyl vinyl ether, o- (trifluoro) methylstyrene, vinyl pentafluorobenzoate, difluoroethylene, tetrafluoroethylene and the like. Vinyl compounds; non-conjugated diene compounds such as 1,4-pentadiene, 1,4-hexadiene, vinyl norbornene, dicyclopentadiene; ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-hexene Α-olefin compounds such as octene; α, β-ethylenically unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, fumaric anhydride, etc. α, β-ethylenically unsaturated polyvalent carboxylic acid And anhydrides thereof; α, β-ethylenically unsaturated carboxylic acid alkyl esters such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; maleic acid Monoethyl, diethyl maleate, monobutyl maleate, dibutyl maleate, monoethyl fumarate, diethyl fumarate, monobutyl fumarate, dibutyl fumarate, monocyclohexyl fumarate, dicyclohexyl fumarate, monoethyl itaconate, diethyl itaconate, monobutyl itaconate , Monoesters and diesters of α, β-ethylenically unsaturated polyvalent carboxylic acids such as dibutyl itaconate; α such as methoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, butoxyethyl (meth) acrylate Alkoxyalkyl esters of β-ethylenically unsaturated carboxylic acids; hydroxyalkyl esters of α, β-ethylenically unsaturated carboxylic acids such as 2-hydroxyethyl (meth) acrylate and 3-hydroxypropyl (meth) acrylate; divinyl Divinyl compounds such as benzene; Di (meth) acrylates such as ethylene di (meth) acrylate, diethylene glycol di (meth) acrylate, and ethylene glycol di (meth) acrylate; Tri (meta) such as trimethylolpropane tri (meth) acrylate In addition to polyfunctional ethylenically unsaturated monomers such as acrylic acid esters; self-crosslinking compounds such as N-methylol (meth) acrylamide and N, N′-dimethylol (meth) acrylamide;

The Mooney viscosity of the nitrile rubber (a) (hereinafter sometimes referred to as “polymer Mooney viscosity”) (ML _{1 + 4} , 100 ° C.) is preferably 3 to 250, more preferably 15 to 180, and still more preferably 20. ~ 160. If the polymer Mooney viscosity of the nitrile rubber (a) is too low, the strength properties of the resulting crosslinked rubber may be lowered. On the other hand, if it is too high, the workability may be deteriorated.

  The nitrile rubber (a) used in the present invention can be produced by copolymerizing each monomer constituting the nitrile rubber (a). The method for copolymerizing each monomer is not particularly limited, but for example, emulsification that obtains a latex of a copolymer having an average particle diameter of about 50 to 1,000 nm using an emulsifier such as sodium dodecylbenzenesulfonate. A polymerization method or a suspension polymerization method (including a fine suspension polymerization method) for obtaining a latex of a copolymer having an average particle size of about 0.2 to 200 μm using a dispersant such as polyvinyl alcohol is preferably used. be able to. Among these, the emulsion polymerization method is more preferable because the polymerization reaction can be easily controlled.

The emulsion polymerization method is preferably performed according to the following procedure.
In the following, the α, β-ethylenically unsaturated nitrile monomer is referred to as “monomer (m1)”, the conjugated diene monomer is referred to as “monomer (m2)”, and a cationic monomer The monomer forming the body unit is referred to as “monomer (m3)”.

  That is, monomer (m1) 20 to 80% by weight, preferably 30 to 70% by weight, more preferably 40 to 60% by weight, monomer (m2) 80 to 20% by weight, preferably 70 to 30% by weight More preferably 60 to 40% by weight, and the monomer (m3) is 0 to 20% by weight, preferably 0.3 to 15% by weight, particularly preferably 0.5 to 10% by weight. The monomer mixture (however, the total amount of the monomer (m1), the monomer (m2) and the monomer (m3) is 100% by weight) is subjected to emulsion polymerization, and the polymerization conversion rate is preferably 50. A method of removing the unreacted monomer as desired after stopping the polymerization reaction at a time of ˜95% by weight is preferable.

  If the amount of the monomer (m1) used in the emulsion polymerization method is too small, the oil resistance and gasoline permeation resistance of the resulting rubber cross-linked product deteriorate, while the amount of the monomer (m1) used is large. If too much, cold resistance tends to deteriorate. If the amount of the monomer (m2) used is too small, the cold resistance of the resulting rubber cross-linked product will deteriorate. On the other hand, if the amount of the monomer (m2) used is too large, the resulting rubber cross-linked product will be gasoline resistant. There is a tendency for permeability to deteriorate. Further, by using the monomer (m3) within the above range, it is possible to further improve the gasoline permeation resistance of the obtained rubber cross-linked product.

  If the polymerization conversion rate for terminating the polymerization reaction is too low, it becomes very difficult to recover the unreacted monomer. On the other hand, if it is too high, the normal physical properties of the resulting rubber cross-linked product will deteriorate.

  In conducting the emulsion polymerization, conventionally known emulsifiers, polymerization initiators, polymerization auxiliary materials and the like can be appropriately used in the field of emulsion polymerization, and the polymerization temperature and polymerization time may be appropriately adjusted.

  In addition, the polymerization reaction may be started using the total amount of the monomers (m1) to (m3) used for the emulsion polymerization, but the composition distribution of each monomer unit of the copolymer to be produced is controlled, and more From the viewpoint of obtaining a rubber cross-linked product rich in rubber elasticity, a polymerization reaction is started using a part of the total amount of monomers (m1) to (m3) used for emulsion polymerization, and then used for emulsion polymerization. The remainder of the bodies (m1) to (m3) is preferably added to the reactor for polymerization. This is because if the total amount of the monomers (m1) to (m3) used for the emulsion polymerization is reacted from the start of the polymerization reaction, the composition distribution of the copolymer may be expanded.

  In this case, the monomer (m1) used for the polymerization is preferably 10 to 100% by weight, more preferably 20 to 100% by weight, particularly preferably 30 to 100% by weight, preferably the monomer (m2) used for the polymerization. Is from 5 to 90% by weight, more preferably from 10 to 80% by weight, particularly preferably from 15 to 70% by weight, and preferably from 0 to 100% by weight, more preferably from 30 to 70% by weight of the monomer (m3) used in the polymerization. A monomer mixture comprising 100% by weight, particularly preferably 70 to 100% by weight, is charged into the reactor, and after the polymerization reaction is started, the polymerization conversion rate with respect to the monomer mixture charged into the reactor is preferably 5 to 80 It is preferable to continue the polymerization reaction by adding the remaining monomer to the reactor in the range of% by weight. Even when the monomer (m3) is not used, the polymerization reaction is started using the above-mentioned amounts of the monomer (m1) and the monomer (m2) used for the polymerization, and the monomer It is preferable to polymerize by adding the remainder of (m1) and (m2) to the reactor.

  The method for adding the remaining monomer is not particularly limited, but it may be added all at once, dividedly, or continuously. In the present invention, from the viewpoint that the composition distribution of the copolymer to be obtained can be more easily controlled, it is preferable to add the remaining monomer in divided portions, and it is particularly preferable to add in one to six portions. preferable. When the remaining monomer is added in divided portions, the amount of the monomer to be added in divided portions and the timing of the divided addition may be adjusted according to the progress of the polymerization reaction so that the desired nitrile rubber (a) is obtained. Good.

  After completion of the polymerization reaction, a latex of the nitrile rubber (a) can be obtained by removing unreacted monomers using a known method such as heating distillation, vacuum distillation, steam distillation or the like, if desired. In the present invention, the solid content concentration of the nitrile rubber (a) latex obtained by the emulsion polymerization method is preferably 5 to 70% by weight, more preferably 10 to 60% by weight, and particularly preferably 15 to 50% by weight. is there.

  The nitrile rubber (a) used in the present invention is obtained by hydrogenating (hydrogenating at least a part of carbon-carbon unsaturated bonds in the conjugated diene monomer unit portion of the copolymer obtained by copolymerization as described above. Hydrogenated nitrile rubber subjected to addition reaction) may be used. The method for hydrogenation is not particularly limited, and a known method may be employed. When the nitrile rubber (a) is a hydrogenated nitrile rubber, the iodine value is preferably in the range of 0 to 70, more preferably in the range of 4 to 60. By hydrogenating the nitrile rubber (a) to obtain a hydrogenated nitrile rubber, heat resistance, weather resistance, ozone resistance and the like can be improved.

  Moreover, the methyl ethyl ketone insoluble content of the nitrile rubber (a) is less than 20 wt%, preferably less than 10 wt%, and the methyl ethyl ketone insoluble content may be substantially 0 wt%.

Polymer (b) having a methyl ethyl ketone insoluble content of 20% by weight or more
The polymer (b) having an insoluble content of methyl ethyl ketone of 20% by weight or more used in the present invention is at least selected from the group consisting of an aromatic vinyl monomer unit and an α, β-ethylenically unsaturated nitrile monomer unit. Containing 50 to 100% by weight of one kind of vinyl monomer unit and 50 to 0% by weight of conjugated diene monomer unit which may be at least partially hydrogenated, and having an insoluble content of methyl ethyl ketone of 20% by weight or more It is a polymer.

  Examples of the aromatic vinyl monomer that forms the aromatic vinyl monomer unit include styrene, α-methylstyrene, p-tert-butylstyrene, and the like, and styrene is preferable. Examples of the α, β-ethylenically unsaturated nitrile monomer forming the α, β-ethylenically unsaturated nitrile monomer unit include those similar to the case of the nitrile rubber (a) described above, and acrylonitrile and Methacrylonitrile is preferred and acrylonitrile is particularly preferred.

  Examples of the conjugated diene monomer forming the conjugated diene monomer unit include the same ones as in the case of the nitrile rubber (a) described above, and 1,3-butadiene is preferable.

  The content ratio of the vinyl monomer units in the polymer (b) is 50 to 100% by weight, preferably 55 to 100% by weight, particularly preferably 60 to 100% by weight, based on all monomer units. When the content ratio of the vinyl monomer unit is less than 50% by weight, the gasoline permeation resistance deteriorates.

  In addition, the α, β-ethylenically unsaturated nitrile monomer unit in the polymer (b) is preferably 10 to 90% by weight, particularly preferably 30 to 80% by weight. The aromatic vinyl monomer unit in the polymer (b) is preferably 0 to 90% by weight, more preferably 0 to 70% by weight, and particularly preferably 0 to 30% by weight.

  The polymer (b) used in the present invention may further contain a cationic monomer unit similar to that in the case of the nitrile rubber (a) described above. The content ratio of the cationic monomer unit is preferably 0 to 30% by weight with respect to the total monomer units.

  Further, the polymer (b) used in the present invention is the same as the above-mentioned nitrile rubber (a) except for the vinyl monomer unit, the conjugated diene monomer unit, and the cationic monomer unit. These may contain other monomer units copolymerizable with the monomers forming the monomer units. The content ratio of such other monomer units is preferably 30% by weight or less, more preferably 20% by weight or less, and particularly preferably 10% by weight or less based on the total monomer units.

  In addition, as a monomer which forms such another monomer unit, the same thing as the case of the above-mentioned nitrile rubber (a) is mentioned.

  Moreover, the weight average molecular weight (polystyrene conversion by GPC) of the tetrahydrofuran soluble part of a polymer (b) becomes like this. Preferably it is 5,000-2,000,000, More preferably, it is 7,000-1,500,000, Furthermore, Preferably it is 10,000-1,000,000, Most preferably, it is 20,000-800,000.

The methyl ethyl ketone insoluble polymer (b) needs to have a methyl ethyl ketone insoluble content of 20% by weight or more. The methyl ethyl ketone insoluble matter was obtained by immersing 1 g of the polymer (b) in 200 ml of methyl ethyl ketone, leaving it to stand at 23 ° C. for 24 hours, filtering using a 325 mesh wire net, evaporating the filtrate by evaporation and solidifying, The solid content [methyl ethyl ketone soluble content: (y) g] is weighed, and the methyl ethyl ketone insoluble content is calculated by the following equation.

    Methyl ethyl ketone insoluble matter (% by weight) = 100 × (1-y) / 1

  The polymer (b) can be produced by copolymerizing each monomer. The method for copolymerizing each monomer is not particularly limited, but for example, emulsification that obtains a latex of a copolymer having an average particle diameter of about 50 to 1,000 nm using an emulsifier such as sodium dodecylbenzenesulfonate. A polymerization method or a suspension polymerization method (including a fine suspension polymerization method) for obtaining a latex of a copolymer having an average particle size of about 0.2 to 200 μm using a dispersant such as polyvinyl alcohol is preferably used. be able to. Among these, the emulsion polymerization method is more preferable because the polymerization reaction can be easily controlled.

  The procedure of the emulsion polymerization method may be the same as described above for the nitrile rubber (a). After completion of the polymerization reaction, a latex of the polymer (b) can be obtained by removing unreacted monomers by using a known method such as heating distillation, vacuum distillation, steam distillation or the like. In the present invention, the latex concentration of the polymer (b) latex obtained by the emulsion polymerization method is preferably 5 to 70% by weight, more preferably 10 to 60% by weight, and particularly preferably 15 to 50% by weight. is there.

  Adjustment of the insoluble matter of methyl ethyl ketone includes (a) decreasing the amount of chain transfer agent and increasing the polymerization temperature, and (b) polyfunctional ethylene such as divinylbenzene, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, etc. By increasing the insoluble content by copolymerizing self-crosslinking compounds such as water-soluble unsaturated monomers, N-methylol (meth) acrylamide, and N, N'-dimethylol (meth) acrylamide Can do.

  When the methyl ethyl ketone insoluble content of the polymer (b) is less than 20% by weight, the gasoline permeation resistance deteriorates. On the other hand, the methyl ethyl ketone insoluble matter of the nitrile rubber (a) is less than 20% by weight, and the methyl ethyl ketone insoluble matter may be substantially 0%. The methyl ethyl ketone insoluble matter of nitrile rubber (a) is the same as that of polymer (b) by using “nitrile rubber (a) 1 g” as a measurement sample instead of “polymer (b) 1 g”. It can be determined by measuring.

  The polymer (b) used in the present invention is a hydrogenated polymer obtained by hydrogenating (hydrogenation reaction) at least a part of the unsaturated bond portion in the conjugated diene monomer unit portion of the polymer (b). There may be. The method for hydrogenation is not particularly limited, and a known method may be employed. When making a polymer (b) into a hydrogenated polymer, the iodine value becomes like this. Preferably it is the range of 0-70, More preferably, it is the range of 4-60. By hydrogenating the polymer (b) to obtain a hydrogenated polymer, heat resistance, weather resistance, ozone resistance and the like can be improved.

Polymer component (A)
The nitrile rubber composition of the present invention contains a polymer component (A) containing 40 to 95% by weight of nitrile rubber (a) and 60 to 5% by weight of polymer (b).

  The ratio of the α, β-ethylenically unsaturated nitrile monomer unit to the polymer component (A) in the total of all monomer units of the nitrile rubber (a) and the polymer (b) is preferably 35. It is desirable that it is ˜65% by weight, more preferably 40 to 62% by weight, in terms of a balance between cold resistance, gasoline permeation resistance and oil resistance.

Plasticizer (B)
The nitrile rubber composition of the present invention contains a specific plasticizer (B). As the plasticizer (B), a plasticizer having an SP value (solubility parameter) by the HOY method of 8.0 to 10.2 (cal / cm ³ ) ^1/2 is used. If the SP value of the plasticizer (B) is too large, the resulting rubber cross-linked product tends to be inferior in cold resistance, and if the SP value is too small, the resulting rubber cross-linked product tends to deteriorate in gasoline permeability resistance. is there. When the plasticizer (B) having an SP value of 8.0 to 10.2 (cal / cm ³ ) ^1/2 is used, the resulting rubber cross-linked product has excellent cold resistance and excellent gasoline permeability resistance. It becomes.

Specific examples of such a plasticizer (B) (the unit of SP value is “(cal / cm ³ ) ^1/2 ”) include, for example, dibutoxyethyl adipate (SP value: 8.8), adipic acid Ester compound of adipic acid such as di (butoxyethoxyethyl) (SP value: 9.2) and ether bond-containing alcohol; azelaic acid such as dibutoxyethyl azelate, azelaic acid di (butoxyethoxyethyl) and ether bond Ester compounds with alcohols; ester compounds of sebacic acid and ether-bonded alcohols such as dibutoxyethyl sebacate and di (butoxyethoxyethyl) sebacate; dibutoxyethyl phthalate, di (butoxyethoxyethyl) phthalate, etc. Ester compound of phthalic acid and ether bond-containing alcohol; isophthalic acid Ester compounds of isophthalic acid such as dibutoxyethyl and di (butoxyethoxyethyl) isophthalate and alcohols containing an ether bond; di- (2-ethylhexyl) adipate (SP value: 8.5), diisodecyl adipate (SP value) : 8.3), diisononyl adipate, dialkyl esters of adipate such as dibutyl adipate (SP value: 8.9); di- (2-ethylhexyl) azelate (SP value: 8.5), diisooctyl azelate , Azelaic acid dialkyl esters such as azelaic acid di-n-hexyl; di-n-butyl sebacate (SP value: 8.7), di- (2-ethylhexyl) sebacate (SP value: 8.4), etc. Of dialkyl esters of sebacic acid: dibutyl phthalate (SP value: 9.4), di- (2-ethylhexyl phthalate) (SP value: 9.0), di-n-octyl phthalate, diisobutyl phthalate, diheptyl phthalate (SP value: 9.0), diisodecyl phthalate (SP value: 8.5), diundecyl phthalate (SP value: 8.5), dialkyl phthalates such as diisononyl phthalate (SP value: 8.9); dicycloalkyl phthalates such as dicyclohexyl phthalate; diphenyl phthalate, butylbenzyl phthalate ( SP value: 10.2) phthalic acid aryl esters; isophthalic acid di- (2-ethylhexyl), isophthalic acid dialkyl esters such as diisooctyl isophthalic acid; tetrahydrophthalic acid di- (2-ethylhexyl), tetrahydrophthalic acid Tetrahydro, such as di-n-octyl and diisodecyl tetrahydrophthalate Lophthalic acid dialkyl esters; trimellitic acid tri- (2-ethylhexyl) (SP value: 8.9), trimellitic acid tri-n-octyl (SP value: 8.9), trimellitic acid triisodecyl (SP value: 8.4), trimellitic acid such as triisooctyl trimellitic acid, tri-n-hexyl trimellitic acid, triisononyl trimellitic acid (SP value: 8.8), triisodecyl trimellitic acid (SP value: 8.8) Acid derivatives; epoxy plasticizers such as epoxidized soybean oil (SP value: 9.0), epoxidized linseed oil (SP value: 9.3); phosphorus such as tricresyl phosphate (SP value: 9.7) And acid ester plasticizers. These can be used individually by 1 type or in combination of multiple types.

  Among these, since the cold resistance and gasoline permeation resistance of the resulting cross-linked product can be improved, dibasic acids such as adipic acid, azelaic acid, sebacic acid and phthalic acid, and an ether bond are contained. An ester compound with an alcohol is preferred, an ester compound of adipic acid and an ether bond-containing alcohol is more preferred, and di (butoxyethoxyethyl) adipate is particularly preferred.

  The content of the plasticizer (B) in the nitrile rubber composition of the present invention is 0.1 to 200 parts by weight, preferably 1 to 150 parts by weight, more preferably 100 parts by weight of the polymer component (A). Is 2 to 100 parts by weight, particularly preferably 5 to 50 parts by weight. When the content of the plasticizer (B) is in the above range, in addition to preventing bleeding, the effect of the present invention becomes even more remarkable.

Thermoplastic resin The nitrile rubber composition of the present invention can contain other rubbers and polymers in addition to the nitrile rubber (a) and the polymer (b) as long as the effects of the present invention are not impaired. It is preferable to further have at least one thermoplastic resin selected from the group consisting of polyvinyl chloride resin and acrylic resin. By containing at least one thermoplastic resin selected from the group consisting of a polyvinyl chloride resin and an acrylic resin, ozone resistance can be further improved when a rubber cross-linked product is obtained.

  With the polyvinyl chloride resin used in the present invention, the main constituent monomer constituting the resin is vinyl chloride, and the content of the monomer unit is preferably 50 to 100% by weight, more preferably 60 to 100% by weight, particularly preferably 70 to 100% by weight. In the acrylic resin used in the present invention, the main constituent monomer constituting the resin is a (meth) acrylic acid alkyl ester, and the content of the monomer unit is preferably 50 to 100% by weight, more preferably Is 60 to 100% by weight, particularly preferably 70 to 100% by weight. Carbon number of an alkyl group becomes like this. Preferably it is 1-20, More preferably, it is 1-18, Most preferably, it is 1-10.

  The average particle diameter of these thermoplastic resins is preferably 0.01 μm to 1 mm, more preferably 0.05 to 100 μm, and particularly preferably 0.1 to 10 μm. The average particle size is measured by a laser diffraction scattering particle size distribution measuring device. If the average particle size of the resin is too small, the ozone resistance of the rubber cross-linked product may be reduced. Conversely, if it is too large, poor dispersion may occur during kneading.

  Moreover, it is preferable that Tg (glass transition temperature) of a thermoplastic resin is 50-180 degreeC, and it is especially preferable that Tg of an acrylic resin is 60-150 degreeC.

  The polymerization degree or molecular weight of the polyvinyl chloride resin and the acrylic resin is not particularly limited, but in the case of the polyvinyl chloride resin, the average polymerization degree according to the solution viscosity method defined in JIS K6721 is preferably 400 to 3,000, more preferably 600-2,000. In the acrylic resin, the number average molecular weight in terms of standard polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent is preferably 10,000 to 7,000,000, more preferably 100,000 to 2,000,000. It is.

  If the degree of polymerization or the molecular weight is too small, the ozone resistance of the rubber cross-linked product may be deteriorated. Conversely, if it is too large, the moldability may be inferior.

  The content of at least one thermoplastic resin selected from the group consisting of a polyvinyl chloride resin and an acrylic resin is preferably 10 to 100 parts by weight, more preferably 20 to 100 parts by weight with respect to 100 parts by weight of the polymer component (A). 85 parts by weight, particularly preferably 30 to 70 parts by weight. If the content of at least one thermoplastic resin selected from the group consisting of polyvinyl chloride resin and acrylic resin is too small, it is difficult to obtain the effect of addition. On the other hand, if too much, cold resistance may be deteriorated.

Inorganic filler In the nitrile rubber composition of the present invention, an inorganic filler having an aspect ratio of 30 to 2,000 is added to the polymer component (A) in order to enhance the penetration blocking effect of gasoline on the obtained rubber cross-linked product. It is preferable to contain in the ratio of 1-100 weight part with respect to 100 weight part. The inorganic filler having an aspect ratio in the above range is a flat plate-like filler. By combining this with the polymer component (A) and the plasticizer (B), the resulting cross-linked product is converted into gasoline-resistant. While the permeability and mechanical strength are good, the cold resistance can be excellent. When the aspect ratio is too small, the gasoline permeation resistance of the resulting rubber cross-linked product is deteriorated. On the other hand, if it is too large, it will be difficult to disperse in the nitrile rubber composition, and the mechanical strength of the crosslinked rubber will decrease. The aspect ratio is more preferably 100 to 1,500, and particularly preferably 200 to 1,000.

  The aspect ratio of the inorganic filler can be calculated by determining the ratio between the average surface diameter and the average thickness of the primary particles of the inorganic filler. Here, the surface average diameter and the average thickness are the values of the number average calculated by measuring the surface diameter and thickness of 100 inorganic fillers randomly selected with an atomic force microscope and calculating the arithmetic average value thereof. It is.

  The average particle diameter (average primary particle diameter) of the inorganic filler is preferably 0.001 to 20 μm, more preferably 0.005 to 15 μm, and still more preferably 0.01 to 10 μm. In the present invention, the average particle size of the inorganic filler is defined as a 50% volume cumulative diameter obtained by measuring the particle size distribution by the X-ray transmission method. If the average particle size of the inorganic filler is too small, the elongation of the resulting rubber cross-linked product may be reduced. Conversely, if it is too large, a stable latex composition may not be prepared.

  The inorganic filler having an aspect ratio of 30 to 2,000 is not particularly limited, and it may be a natural product or a synthetic product, regardless of whether it is derived from a natural product or a natural product subjected to a treatment such as purification. There may be. Specific examples include kaolinites such as kaolinite and halosite; smectites such as montmorillonite, beidellite, nontronite, saponite, hectorite, stevensite, mica; and vermiculites; chlorite; talc; E Examples thereof include glass flakes which are amorphous plate-like particles such as glass or C glass. Of these, smectites are preferable, and montmorillonite, mica, and saponite are particularly preferable.

  Here, among the above, montmorillonite is contained as a main component in bentonite. Therefore, as montmorillonite, bentonite, preferably obtained by purifying can be used.

  The content of the inorganic filler is preferably 1 to 100 parts by weight, more preferably 3 to 75 parts by weight, and particularly preferably 5 to 50 parts by weight with respect to 100 parts by weight of the polymer component (A). . If the content of the inorganic filler is too small, the gasoline permeation resistance tends to deteriorate. On the other hand, when there is too much content, it exists in the tendency for the elongation of the rubber crosslinked material obtained to fall.

  Note that montmorillonite, mica, and saponite have a multilayer structure having exchangeable cations between layers, and thus have excellent dispersibility in the cationic monomer units in the nitrile rubber (A).

Preparation of Nitrile Rubber Composition The method for preparing the nitrile rubber composition of the present invention is not particularly limited, but is preferably performed by the following method.

  That is, as the nitrile rubber (a) and the polymer (b), those obtained as a polymer latex having an average particle size of preferably 0.05 to 10 μm by emulsion polymerization or suspension polymerization, respectively, are mixed. In addition, a plasticizer is added as an aqueous emulsion and mixed. The latex composition is coagulated to form a crumb, filtered, washed and then dried to obtain a mixture containing nitrile rubber (a), polymer (b) and a plasticizer. Knead the other ingredients. When this method is adopted, the nitrile rubber (a), the polymer (b) and the plasticizer are uniformly mixed, and the plasticizer is less likely to bleed, and the rubber cross-linking excellent in gasoline permeability resistance and cold resistance. Things are easy to get.

  The method for preparing the aqueous plasticizer emulsion is not particularly limited, but the plasticizer is added while vigorously stirring the aqueous medium containing the surfactant in an amount of 0.5 to 10% by weight of the plasticizer. It is preferable to prepare. Surfactants include anionic surfactants such as potassium rosinate, sodium lauryl sulfate, potassium oleate, sodium dodecylbenzenesulfonate; polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan alkyl ester, etc. Nonionic surfactants such as: cationic surfactants such as didecyldimethylammonium chloride and stearyltrimethylammonium chloride. In addition, it is preferable that the plasticizer density | concentration of an aqueous emulsion shall be 5-70 weight%.

  The method for coagulating the latex composition is not particularly limited, but a known method such as salting out coagulation is applied. Among these, it is preferable to carry out by salting out the latex composition by adding it to an aqueous solution containing a coagulant. Examples of the coagulant include calcium chloride, sodium chloride, calcium hydroxide, aluminum sulfate, and aluminum hydroxide. The amount of the coagulant used is preferably 0.5 to 150 parts by weight, particularly preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the nitrile rubber (a).

  Here, when one or both of the nitrile rubber (a) and the polymer (b) contain a cationic monomer unit, a dilute sulfuric acid aqueous solution or the like is used when salting out the latex composition. It is preferable to control the pH of the aqueous coagulant solution to be equal to or lower than the isoelectric point of the latex composition of the nitrile copolymer (A). By controlling the pH of the aqueous solution of the coagulant, the zeta potential of the functional group of the cationic monomer unit contained in one or both of the nitrile rubber (a) and the polymer (b) is increased. The dispersibility of the filler is improved, and the crumb particle size obtained by solidification can be increased. The crumb particle size greatly affects the degree of dehydration in the vibrating screen and squeezer following the coagulation and washing process, the crumb recovery rate, and the dryness in the drying process. It is preferably 5 to 40 mm. The crumb washing, dehydration and drying methods are the same as the washing / dehydration and drying methods in general rubber production. As a washing / dehydrating method, a crumb obtained by coagulation and water may be separated using a mesh filter, a centrifugal separator, etc., then washed, and the crumb may be dehydrated with a squeezer or the like. Next, the nitrile rubber composition of the present invention can be obtained by drying to a desired moisture content by a band drier, a twin screw extruder or the like generally used for rubber production. Moreover, you may perform coagulation | solidification and drying simultaneously within a twin-screw extruder.

  When the nitrile rubber composition of the present invention contains at least one thermoplastic resin selected from the group consisting of a polyvinyl chloride resin and an acrylic resin, a latex-state polymer produced by a conventionally known emulsion polymerization method is used. A vinyl chloride resin or an acrylic resin may be mixed (latex blend) with the latex composition containing the polymer component (A) and the plasticizer (B) prepared as described above.

  Further, a polyvinyl chloride resin or an acrylic resin is rolled into a rubber composition obtained by coagulating and drying the latex composition containing the polymer component (A) and the plasticizer (B) prepared as described above. You may knead with kneading machines, such as a Banbury mixer.

  The method for incorporating the inorganic filler having an aspect ratio of 30 to 2,000 in the nitrile rubber composition of the present invention is not particularly limited, but the polymer component (A) and the plasticizer (prepared as described above) What is necessary is just to add the aqueous dispersion of a flat inorganic filler to the latex composition containing B) under stirring.

  The rubber composition obtained by coagulating the latex composition and drying as necessary, is added with components such as filler, anti-aging agent, reinforcing agent, kneading machines such as rolls and Banbury mixers The nitrile rubber composition of the present invention is prepared by kneading with the above.

  As a method for preparing the nitrile rubber composition of the present invention, in addition to the method described above, for example, a plasticizer, a flat inorganic filler added as necessary to the latex of the nitrile rubber (a), In addition, all the components of polyvinyl chloride resin or acrylic resin added as necessary, or the total amount of one or more components or a part thereof are contained, and then coagulated and dried to obtain a filler and an anti-aging agent. It can also be obtained by kneading ingredients such as reinforcing agents with a kneading machine such as a roll or a Banbury mixer.

  In addition, the nitrile rubber composition of the present invention includes a nitrile rubber (a), a polymer (b), and a polymer other than the above-described polyvinyl chloride resin and acrylic resin as long as the effects of the present invention are not impaired. You may make it contain. The polymer other than the nitrile rubber (a) and the polymer (b) is not particularly limited, but acrylic rubber, ethylene-acrylic acid copolymer rubber, fluororubber, ethylene-propylene copolymer rubber, ethylene-propylene- Examples thereof include diene terpolymer rubber, epichlorohydrin rubber, urethane rubber, chloroprene rubber, ethylene-vinyl acetate copolymer, chlorosulfonated polyethylene, natural rubber, and polyisoprene rubber. The blending amount in the case of blending other polymer is preferably 100 parts by weight or less, more preferably 50 parts by weight or less, and further preferably 30 parts by weight or less, with respect to 100 parts by weight of the nitrile rubber (a). The amount is particularly preferably 10 parts by weight or less.

Crosslinkable nitrile rubber composition The crosslinkable nitrile rubber composition of the present invention comprises the nitrile rubber composition of the present invention containing a crosslinking agent. Examples of the crosslinking agent include a sulfur-based crosslinking agent and an organic peroxide crosslinking agent. Although these can be used individually by 1 type or in combination of multiple types, it is preferable to use a sulfur type crosslinking agent.

  Sulfur-based crosslinking agents include powdered sulfur, sulfur white, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, and other sulfur; sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, dibenzothiazyl disulfide, N, Sulfur-containing compounds such as N′-dithio-bis (hexahydro-2H-azenopine-2), phosphorus-containing polysulfides, polymer polysulfides; tetramethylthiuram disulfide, selenium dimethyldithiocarbamate, 2- (4′-morpholinodithio) And sulfur donating compounds such as benzothiazole; These can be used individually by 1 type or in combination of multiple types.

  Examples of the organic peroxide crosslinking agent include dicumyl peroxide, cumene hydroperoxide, t-butylcumyl peroxide, paramentane hydroperoxide, di-t-butyl peroxide, 1,3-bis (t-butylperoxyisopropyl) benzene, 1,4-bis (t-butylperoxyisopropyl) benzene, 1,1-di-t-butylperoxy-3,3-trimethylcyclohexane, 4,4-bis- (t-butyl-peroxy) -n-butylvale 2,5-dimethyl-2,5-di-t-butylperoxyhexane, 2,5-dimethyl-2,5-di-t-butylperoxyhexyne-3, 1,1-di-t-butyl Peroxy-3,5,5-trimethylcyclohexane, p-chlorobenzoyl peroxide, t-butylperoxy Propyl carbonate, t- butyl peroxybenzoate, and the like. These can be used individually by 1 type or in combination of multiple types.

  The content of the crosslinking agent in the crosslinkable nitrile rubber composition formed from the nitrile rubber composition of the present invention is not particularly limited, but is 100 parts by weight in total of the nitrile rubber (a) and the polymer (b). The amount is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight.

  When an organic peroxide crosslinking agent is used, a multifunctional monomer such as trimethylolpropane trimethacrylate, divinylbenzene, ethylene dimethacrylate, or triallyl isocyanurate can be used in combination as a crosslinking aid. Although the usage-amount of these crosslinking adjuvants is not specifically limited, Preferably it is the range of 0.5-20 weight part with respect to a total of 100 weight part of nitrile rubber (a) and a polymer (b).

  When using a sulfur-based crosslinking agent, a crosslinking assistant such as zinc white or stearic acid; a crosslinking accelerator such as guanidine, aldehyde-amine, aldehyde-ammonia, thiazole, sulfenamide, thiourea Can be used in combination. The amounts of these crosslinking aids and crosslinking accelerators are not particularly limited, and are preferably in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the nitrile rubber (a).

  In addition, the crosslinkable nitrile rubber composition formed from the nitrile rubber composition of the present invention includes other compounding agents used for general rubber as necessary, for example, a crosslinking retarder, an anti-aging agent, a lubricant, Additives such as pressure-sensitive adhesives, lubricants, processing aids, flame retardants, antifungal agents, antistatic agents, and coloring agents may be blended. As the anti-aging agent, an anti-aging agent such as phenol, amine, benzimidazole or phosphoric acid can be used. In the phenol system, 2,2′-methylenebis (4-methyl-6-tert-butylphenol) and the like are used, and in the amine system, 4,4′-bis (α, α-dimethylbenzyl) diphenylamine, N-isopropyl-N ′. -Phenyl-p-phenylenediamine and the like, and benzimidazole type include 2-mercaptobenzimidazole and the like. These may be used alone or in combination of two or more.

  The method for preparing the crosslinkable nitrile rubber composition of the present invention is not particularly limited, but a nitrile rubber composition obtained by the above method is added with a crosslinking agent, a crosslinking aid and other compounding agents, What is necessary is just to knead with kneading machines, such as a Banbury mixer. In this case, the blending order is not particularly limited, but components (such as a crosslinking agent and a crosslinking accelerator) that are easily decomposed by heat after sufficiently mixing components that are not easily reacted or decomposed by heat do not decompose. What is necessary is just to mix in temperature for a short time.

The crosslinkable nitrile rubber composition of the present invention has a Mooney viscosity (hereinafter sometimes referred to as “compound Mooney viscosity”) (ML _{1 + 4} , 100 ° C.) of preferably 5 to 300, more preferably 10 to 250. is there.

Cross-linked rubber The cross-linked rubber of the present invention is obtained by cross-linking the cross-linkable nitrile rubber composition.

  When the crosslinkable nitrile rubber composition is crosslinked, it is molded by a molding machine corresponding to the shape of the molded article (rubber crosslinked product) to be produced, for example, an extruder, an injection molding machine, a compressor, a roll, etc. The shape of the crosslinked product is fixed by crosslinking reaction. When cross-linking is performed, the cross-linking may be performed after molding or may be performed simultaneously with the molding. The molding temperature is usually 10 to 200 ° C, preferably 25 to 120 ° C. The crosslinking temperature is usually 100 to 200 ° C., preferably 130 to 190 ° C., and the crosslinking time is usually 1 minute to 24 hours, preferably 2 minutes to 1 hour.

  Depending on the shape, size, etc. of the rubber cross-linked product, even if the surface is cross-linked, it may not be sufficiently cross-linked to the inside. Therefore, secondary cross-linking may be performed by heating.

  The rubber cross-linked product of the present invention thus obtained is a nitrile rubber cross-linked product excellent in gasoline permeation resistance and cold resistance in addition to the original characteristics of nitrile rubber having good oil resistance.

  As a result, the nitrile rubber composition of the present invention and the cross-linked product thereof are suitable for use in many fields such as fuel hoses and fuel seals, and the transpiration amount of fuel such as gasoline into the atmosphere is reduced. By reducing, the effect which can reduce the load to an environment can be show | played.

  The rubber cross-linked product of the present invention is suitably used as a fuel hose or the like by forming a hose consisting of one layer or two or more layers having at least one layer of the rubber cross-linked product of the present invention. In the case of a laminate of two or more layers, the layer made of the rubber cross-linked product of the present invention may be used for any of the inner layer, intermediate layer, and outer layer. As other layers of the laminate, in addition to the nitrile rubber having an α, β-ethylenically unsaturated nitrile monomer unit content of preferably 5 to 35% by weight, more preferably 18 to 30% by weight, the nitrile Rubber containing polyvinyl chloride resin or acrylic resin, fluoro rubber, chloroprene rubber, hydrin rubber, chlorosulfonated polyethylene rubber, acrylic rubber, ethylene-acrylic acid copolymer, ethylene-propylene copolymer, ethylene- Propylene-diene terpolymer, butyl rubber, isoprene rubber, natural rubber, styrene-butadiene copolymer, fluororesin, polyamide resin, polyvinyl alcohol, ethylene-vinyl acetate copolymer resin, ethylene-vinyl alcohol copolymer resin, Polybutylene naphthalate, polyphenylene sulfide, poly Olefin resins, and polyester resins. These can be used individually by 1 type or in combination of multiple types.

  Further, if necessary, in order to adhere the layer made of the rubber cross-linked product of the present invention and the other layer, a phosnium salt is present in either / or both of the layer made of the rubber cross-linked product of the present invention and the other layer. 1,8-diazabicyclo (5.4.0) undecene-7 salt (DBU salt), 1,5-diazabicyclo (4.3.0) -nonene-5 salt (DBN salt), and the like. .

  The method for producing the hose including the rubber cross-linked product of the present invention having the above-described configuration is not particularly limited, but the hose can be produced by forming into a cylindrical shape using an extruder or the like and crosslinking it. it can. The crosslinkable nitrile rubber composition formed from the nitrile rubber composition of the present invention has the property that mandrel cracks are unlikely to occur, and therefore can be produced using a mandrel. That is, when the hose is a single layer made only of the crosslinked nitrile rubber of the present invention, the crosslinkable nitrile rubber composition formed from the nitrile rubber composition of the present invention is first molded into a cylindrical shape. The shape can be fixed by inserting a mandrel into the obtained cylindrical molded body, and the crosslinkable nitrile rubber composition can be crosslinked.

  The rubber cross-linked product of the present invention includes seal members such as packing, gasket, O-ring and oil seal; hoses such as oil hose, fuel hose, inlet hose, gas hose, brake hose and refrigerant hose; diaphragms; accumulator prada; Suitable for boots; Examples of the gas of the gas hose include air, nitrogen, oxygen, hydrogen, carbon dioxide, carbon monoxide, methane, ethane, propane, dimethyl ether, LPG, and water vapor.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples. Tests or evaluation methods for physical properties and characteristics are as follows. In the following, “part” means “part by weight”.

(1) Mooney viscosity (polymer Mooney viscosity) [ML _{1 + 4} (100 ° C.)]
The polymer Mooney viscosity [ML _{1 + 4} (100 ° C.)] was measured according to JIS K6300.

(2) Normal physical properties (tensile strength, elongation, 100% tensile stress, hardness)
The nitrile rubber composition was put into a mold having a length of 15 cm, a width of 15 cm, and a depth of 0.2 cm, and press-molded at 160 ° C. for 20 minutes while applying pressure of 10 MPa to obtain a sheet-like rubber cross-linked product. The obtained sheet-like rubber cross-linked product was punched with a JIS No. 3 dumbbell to prepare a test piece. The tensile strength, elongation and 100% tensile stress of the crosslinked product were measured according to JIS K6251 using these test pieces. The hardness of the crosslinked product was measured using a durometer hardness tester type A in accordance with JIS K6253.

(3) Cold resistance For cold resistance, the brittle temperature (° C.) was measured according to JIS K6261 for the sheet-like rubber cross-linked product obtained in the same manner as (2) above. The lower the embrittlement temperature, the better the cold resistance.

(4) Gasoline permeation resistance Gasoline permeation was measured by an aluminum cup method using test fuel oil CE-20 (volume ratio: isooctane / toluene / ethanol = 40/40/20). That is, 50 ml of test fuel oil CE-20 was put into a 100 ml capacity aluminum cup, and the sheet-like rubber obtained in the same manner as (2) above having a thickness of 2 mm cut into a disk shape having a diameter of 61 mm. Cover with a cross-linked product, and adjust with a fastener so that the area separating the inside and outside of the aluminum cup is 25.50 cm ² , and leave the aluminum cup in a constant temperature bath at 23 ° C. every 24 hours. The permeation amount of the test fuel oil every 24 hours was measured, and the maximum value was defined as the gasoline permeation amount P (unit: g · mm / m ² · day). The smaller the gasoline permeation, the better the gasoline permeation resistance.

(5) Methyl ethyl ketone insoluble matter 1 g of the polymer was immersed in 200 ml of methyl ethyl ketone, allowed to stand at 23 ° C. for 24 hours, filtered using a 325 mesh wire net, the filtrate was evaporated to dryness, and the resulting dry solid content was obtained. [Methyl ethyl ketone soluble matter: (y) g] was weighed, and methyl ethyl ketone insoluble matter was calculated by the following formula.
Methyl ethyl ketone insoluble matter (% by weight) = 100 × (1-y) / 1

[Example 1]
Production Example 1 ( Production of latex of nitrile rubber (a1))
A reaction vessel was charged with 240 parts of water, 42 parts of acrylonitrile and 2.5 parts of sodium dodecylbenzenesulfonate (emulsifier), and the temperature was adjusted to 5 ° C. Next, after the gas phase was depressurized and sufficiently deaerated, 52 parts of 1,3-butadiene, 0.06 part of paramentane hydroperoxide as a polymerization initiator, 0.02 part of sodium ethylenediaminetetraacetate, first sulfuric acid sulfate First stage reaction of emulsion polymerization was started by adding 0.006 part of iron (7 water salt) and 0.06 part of sodium formaldehyde sulfoxylate and 1 part of t-dodecyl mercaptan as a chain transfer agent. When the polymerization conversion rate with respect to the charged monomer reached 42% by weight, 10 parts of 1,3-butadiene was added to the reaction vessel to carry out the second stage polymerization reaction. Thereafter, when the polymerization conversion ratio with respect to all charged monomers reached 75% by weight, 0.3 part of hydroxylamine sulfate and 0.2 part of potassium hydroxide were added to stop the polymerization reaction. After the reaction was stopped, the contents of the reaction vessel were heated to 70 ° C., and the unreacted monomer was recovered by steam distillation under reduced pressure to obtain a latex of nitrile rubber (a1) (solid content: 24% by weight). It was.

  A part of the latex was sampled, coagulated with a large amount of methanol, filtered and dried to obtain a nitrile rubber (a1). When the content ratio of each monomer unit constituting the obtained nitrile rubber (a1) was measured using an FT-NMR apparatus (JNM-EX400WB) manufactured by JEOL Ltd., 42% by weight of acrylonitrile monomer unit was obtained. The 1,3-butadiene unit was 58% by weight. Moreover, the Mooney viscosity (polymer Mooney viscosity) of the nitrile rubber (a1) was 68, and the insoluble matter in methyl ethyl ketone was 0.1% by weight.

Production Example 2 ( Production of latex of polymer (b1))
A reaction vessel was charged with 240 parts of water, 24 parts of styrene, 45 parts of acrylonitrile and 2.5 parts of sodium dodecylbenzenesulfonate (emulsifier), and the temperature was adjusted to 20 ° C. Next, after depressurizing and sufficiently degassing the gas phase, 31 parts of 1,3-butadiene, 0.06 part of paramentane hydroperoxide as a polymerization initiator, 0.02 part of sodium ethylenediaminetetraacetate, first sulfuric acid sulfate First stage reaction of emulsion polymerization was started by adding 0.006 part of iron (7 water salt) and 0.06 part of sodium formaldehyde sulfoxylate and 0.05 part of chain transfer agent t-dodecyl mercaptan. When the polymerization conversion ratio with respect to all charged monomers reached 75% by weight, 0.3 part of hydroxylamine sulfate and 0.2 part of potassium hydroxide were added to stop the polymerization reaction. After the reaction was stopped, the contents of the reaction vessel were heated to 70 ° C., and unreacted monomers were recovered by steam distillation under reduced pressure to obtain a latex of polymer (b1) (solid content: 20% by weight). It was.

  The content ratio of each monomer unit constituting the obtained polymer (b1) was replaced with a FT-NMR apparatus manufactured by JEOL Ltd., and a solid NMR measurement apparatus (Bruker BioSpin Corporation, ADVANCE III400) was used. The amount of styrene monomer unit was 20% by weight, the amount of acrylonitrile monomer unit was 40% by weight, and the amount of 1,3-butadiene unit was 40% by weight. Further, the methyl ethyl ketone insoluble matter of the obtained copolymer was 60% by weight.

(Preparation of nitrile rubber composition)
50 weight of di (butoxyethoxyethyl) adipate as a plasticizer (B) [trade name “Adekasizer RS-107” manufactured by Asahi Denka Kogyo; SP value 9.2 (cal / cm ³ ) ^1/2 ] A% aqueous emulsion was prepared by mixing 2% by weight of the plasticizer with potassium oleate as an emulsifier and mixing under strong agitation.

  While stirring the nitrile rubber (a1) latex produced in Production Example 1 in a container, the polymer produced in Production Example 2 (b1) with respect to 60 parts of the solid content (nitrile rubber amount) of the nitrile rubber (a1) latex ) Latex (containing 40 parts of polymer (b1)) was added and dispersed.

  Adipic acid prepared above with respect to a total of 100 parts (in terms of solid content) of nitrile rubber (a1) and polymer (b1) in latex in which nitrile rubber (a1) and polymer (b1) are dispersed 30 parts of an emulsion containing di (butoxyethoxyethyl) (15 parts of plasticizer) was added and mixed and dispersed to obtain a nitrile rubber copolymer latex composition.

The obtained nitrile rubber copolymer latex composition was used in an amount of 4% by weight of calcium chloride (coagulant) based on the total amount of nitrile rubber (a1) and polymer (b1) in the latex composition. 10% dilute sulfuric acid is appropriately added to the aqueous solution containing 2 to adjust the pH so that the pH of the aqueous solution during coagulation becomes 2, and the solution is poured and stirred to solidify the nitrile rubber (a1) and the polymer ( A crumb consisting of a mixture of b1) was produced. The content of acrylonitrile in the polymer component (A) in the crumb is
42 wt% x (60/100) + 40 wt% x (40/100) = 41.2 wt%.

  The obtained crumb was filtered and washed with water, and then dried under reduced pressure at 60 ° C. to obtain a nitrile rubber composition.

(Preparation of crosslinkable nitrile rubber composition and production of crosslinked nitrile rubber)
Next, using a Banbury mixer, 10 parts of MT carbon black (“Thermax® medium thermal carbon black N990”, manufactured by CANCARB) per 100 parts of nitrile rubber (a1) in the nitrile rubber composition, as a crosslinking aid 5 parts of zinc white and 1 part of stearic acid were added and mixed at 50 ° C. Then, this mixture was transferred to a roll and 0.5 parts of 325 mesh sulfur as a crosslinking agent and 1.5 parts of tetramethylthiuram disulfide (trade name “Noxeller TT”, manufactured by Ouchi Shinsei Chemical Co., Ltd.), and N-cyclohexyl were used. -2-Benzothiazolylsulfenamide (trade name “Noxeller CZ”, manufactured by Ouchi Shinsei Chemical Co., Ltd., crosslinking accelerator) 1.5 parts was added and kneaded at 50 ° C. to obtain a crosslinkable nitrile rubber composition. Prepared.

  About the rubber cross-linked product obtained by cross-linking the obtained cross-linkable nitrile copolymer rubber composition, normal properties (tensile strength, elongation, 100% tensile stress, hardness), cold resistance, gasoline permeation resistance Each evaluation was performed. The results are shown in Table 1.

[Example 2]
In Example 1, when the nitrile rubber was produced, the monomer charged for the first stage of the emulsion polymerization was changed to 75.7 parts of acrylonitrile and 22 parts of 1,3-butadiene, respectively. Started. When the polymerization conversion ratio with respect to the charged monomer reached 42% by weight and when it reached 60% by weight, 12 parts of 1,3-butadiene were added to the reaction vessel, respectively, in the second and third stages. An eye polymerization reaction was performed. Thereafter, when the polymerization conversion rate with respect to all charged monomers reached 75% by weight, 0.3 part of hydroxylamine sulfate and 0.2 part of potassium hydroxide were added to terminate the polymerization reaction. After the reaction was stopped, the contents of the reaction vessel were heated to 70 ° C., and unreacted monomer was recovered by steam distillation under reduced pressure to obtain a nitrile rubber (a2) latex (solid content: 24% by weight). It was.

  When the content ratio of each monomer unit constituting the obtained nitrile rubber (a2) was measured in the same manner as in Production Example 1, acrylonitrile monomer unit 50% by weight, 1,3-butadiene unit 50% by weight. Met. Moreover, the Mooney viscosity (polymer Mooney viscosity) of the nitrile rubber (a2) was 75, and the insoluble matter in methyl ethyl ketone was 0.2% by weight.

  And the nitrile rubber composition was prepared like Example 1 except having used the obtained nitrile rubber (a2), and it evaluated similarly. The results are shown in Table 1.

[Comparative Example 1]
In Example 2, a nitrile rubber composition was used in the same manner as in Example 2 except that the latex of the polymer (b1) was not used and the solid content (nitrile rubber amount) of the nitrile rubber (a2) latex was changed to 100 parts. Were prepared and evaluated in the same manner. The results are shown in Table 1.

[Comparative Example 2]
In Example 1, when the nitrile rubber was produced, the monomer charged for the first stage of emulsion polymerization was changed to 95.5 parts of acrylonitrile and 3 parts of 1,3-butadiene, respectively, and the first stage reaction was carried out. Started. After the start of the reaction, when the polymerization conversion ratio with respect to the charged monomer reached 12% by weight, 22% by weight, 32% by weight, 42% by weight and 52% by weight, respectively, 3 parts, 3 parts, 3 parts, 4 parts and 4 parts were added to carry out the second, third, fourth, fifth and sixth stage polymerization reactions. Thereafter, when the polymerization conversion rate with respect to all charged monomers reached 60% by weight, 0.3 part of hydroxylamine sulfate and 0.2 part of potassium hydroxide were added to stop the polymerization reaction. After stopping the reaction, the contents of the reaction vessel were heated to 70 ° C., and unreacted monomers were recovered by steam distillation under reduced pressure to obtain latex of nitrile rubber (a3) (solid content 20% by weight). . The nitrile rubber (a3) had a monomer content of 60% by weight of acrylonitrile monomer units, 40% by weight of 1,3-butadiene units, and a Mooney viscosity of 83.

  And the nitrile rubber composition was prepared like Example 2 except having used the obtained nitrile rubber (a3), and it evaluated similarly. The results are shown in Table 1.

[Comparative Example 3]
In Example 1, when producing nitrile rubber, the same procedure as in Example 1 was conducted except that the monomer charged in the first stage of emulsion polymerization was changed to 23 parts of acrylonitrile and 70 parts of 1,3-butadiene. A polymerization reaction was performed to obtain a nitrile rubber (a4) having an acrylonitrile monomer unit of 30% by weight, a 1,3-butadiene unit of 70% by weight and a Mooney viscosity of 69. And the nitrile rubber composition was prepared like Example 2 except having used the obtained nitrile rubber (a4), and it evaluated similarly. The results are shown in Table 1.

[Comparative Example 4]
In Example 2, except that the solid content (nitrile rubber amount) of the nitrile rubber (a2) latex was changed to 97 parts, and the solid content (polymer (b1) amount) of the polymer (b1) latex was changed to 3 parts. A nitrile rubber composition was prepared in the same manner as in Example 2 and evaluated in the same manner. The results are shown in Table 1.

[Comparative Example 5]
In Example 2, except that the solid content (nitrile rubber amount) of the nitrile rubber (a2) latex was changed to 30 parts, and the solid content (polymer (b1) amount) of the polymer (b1) latex was changed to 70 parts. A nitrile rubber composition was prepared in the same manner as in Example 2 and evaluated in the same manner. The results are shown in Table 1.

(Note) (* 1) Acrylonitrile, (* 2) 1,3-butadiene, (* 3) 2-vinylpyridine, (* 4) Styrene. The same applies to Tables 2-5.

  As can be seen from Example 2 and Comparative Example 1, blending the polymer (b1) has an effect of improving the gasoline permeation resistance while improving the cold resistance. Further, in Example 1 using the nitrile rubber (a1) having a low content of acrylonitrile, although the gasoline permeation resistance was slightly lowered, the cold resistance was further improved and a substantially balanced physical property was realized.

  On the other hand, as in Comparative Example 2, in the nitrile rubber (a3) in which the content ratio of acrylonitrile exceeds 54% by weight defined in the present invention, the gasoline permeation resistance is improved, but the cold resistance is −3 ° C. However, it was very unbearable for use in cold regions. On the other hand, when the content of acrylonitrile in the nitrile rubber (a4) is less than 36% by weight as defined in the present invention as in Comparative Example 3, the gasoline permeation resistance is significantly deteriorated. For example, for applications such as transportation hoses. It cannot be used at all.

  Further, when the blending amount of the polymer (b1) is less than the amount specified in the present invention as in Comparative Example 4, the cold resistance is hardly improved and the gasoline permeation resistance is not improved. Moreover, when the compounding quantity of a polymer (b1) exceeds the quantity prescribed | regulated by this invention like the comparative example 5, not only cold resistance will deteriorate notably, but gasoline permeability resistance may also deteriorate. I understood.

[Example 3]
In Example 1, when the polymer (b1) was produced, the monomer charged for the first stage of emulsion polymerization was added to 8.5 parts of styrene, 85 parts of acrylonitrile and 6.5 parts of 1,3-butadiene. The amount of t-dodecyl mercaptan of the chain transfer agent was changed to 0.5 part, and the first stage reaction was started. When the polymerization conversion ratio with respect to the charged monomer reaches 36% by weight and 56% by weight, 9 parts of 1,3-butadiene are added to the reaction vessel respectively in the second and third stages. An eye polymerization reaction was performed. Thereafter, when the polymerization conversion rate with respect to all charged monomers reached 70% by weight, 0.3 part of hydroxylamine sulfate and 0.2 part of potassium hydroxide were added to terminate the polymerization reaction. After the reaction was stopped, the contents of the reaction vessel were heated to 70 ° C., and the unreacted monomer was recovered by steam distillation under reduced pressure to obtain a latex of polymer (b2) (solid content: 20% by weight). It was.

  When the content ratio of each monomer unit constituting the obtained polymer (b2) was measured in the same manner as in Production Example 2, the styrene monomer unit was 10% by weight, the acrylonitrile monomer unit was 60% by weight, The 1,3-butadiene unit was 30% by weight. Further, the methyl ethyl ketone insoluble matter of the obtained copolymer was 35% by weight. And the nitrile rubber composition was prepared like Example 2 except having used the obtained polymer (b2), and it evaluated similarly. The results are shown in Table 2.

[Example 4]
In Example 1, when the polymer (b1) was produced, the preparation monomer for the first stage of emulsion polymerization was changed to 7 parts of styrene and 93 parts of acrylonitrile without using 1,3-butadiene. Then, the first stage reaction was started. When the polymerization conversion ratio with respect to the charged monomer reaches 22% by weight, 40% by weight and 54% by weight, 6 parts, 5 parts and 5 parts of styrene are added to the reaction vessel, respectively. Then, the second, third and fourth stage polymerization reactions were carried out. Thereafter, when the polymerization conversion ratio with respect to all monomers charged reached 65% by weight, 0.3 part of hydroxylamine sulfate and 0.2 part of potassium hydroxide were added to stop the polymerization reaction. After stopping the reaction, the contents of the reaction vessel were heated to 70 ° C., and unreacted monomers were recovered by steam distillation under reduced pressure to obtain a latex (solid content: 20% by weight) of the polymer (b3). It was. When the content ratio of each monomer unit constituting the obtained polymer (b3) was measured in the same manner as in Production Example 2, the styrene monomer unit was 30% by weight and the acrylonitrile monomer unit was 70% by weight. there were. Moreover, the methyl ethyl ketone insoluble matter of the obtained polymer was 56 weight%. And the nitrile rubber composition was prepared like Example 2 except having used the obtained polymer (b3), and it evaluated similarly. The results are shown in Table 2.

[Example 5]
In Example 1, when the polymer (b1) was produced, it was changed to 95 parts of acrylonitrile and 5 parts of 1,3-butadiene, respectively, without using styrene as a charge monomer for the first stage of emulsion polymerization. In addition, the amount of t-dodecyl mercaptan of the chain transfer agent was changed to 0.5 part, and the first stage reaction was started. After the start of the reaction, when the polymerization conversion ratio with respect to the charged monomer reached 20% by weight, reached 38% by weight, and reached 53% by weight, 1,3-butadiene was added to the reaction vessel at 5% each. Part, 4.5 parts and 4 parts were added to carry out the second, third and fourth stage polymerization reactions. Thereafter, when the polymerization conversion ratio with respect to all monomers charged reached 65% by weight, 0.3 part of hydroxylamine sulfate and 0.2 part of potassium hydroxide were added to stop the polymerization reaction. After stopping the reaction, the contents of the reaction vessel are heated to 70 ° C., and unreacted monomers are recovered by steam distillation under reduced pressure to obtain a latex (solid content: 20% by weight) of the polymer (b4). It was.

  When the content ratio of each monomer unit constituting the obtained polymer (b4) was measured in the same manner as in Production Example 2, acrylonitrile monomer unit 75% by weight, 1,3-butadiene unit 25% by weight. Met. The methyl ethyl ketone insoluble matter of the obtained polymer was 57% by weight. And the nitrile rubber composition was prepared like Example 2 except having used the obtained polymer (b4), and it evaluated similarly. The results are shown in Table 2.

[Comparative Example 6]
In Example 1, when the polymer (b1) was produced, the monomer charged for the first stage of emulsion polymerization was changed to 25 parts of styrene, 44 parts of acrylonitrile and 31 parts of 1,3-butadiene, The polymerization reaction was conducted in the same manner as in Example 1 except that the amount of t-dodecyl mercaptan of the chain transfer agent was changed to 1.0 part, and the styrene monomer unit was 20% by weight and the acrylonitrile monomer unit was 40% by weight. Thus, a polymer (b5) having 40% by weight of 1,3-butadiene units and 2% by weight of insoluble matter in methyl ethyl ketone was obtained. And the nitrile rubber composition was prepared like Example 2 except having used the obtained polymer (b5), and it evaluated similarly. The results are shown in Table 2.

[Comparative Example 7]
In Example 1, when the polymer (b1) was produced, the monomer charged for the first stage of emulsion polymerization was added to 15.5 parts of styrene, 15.5 parts of acrylonitrile and 69 parts of 1,3-butadiene, respectively. Except for the change, the polymerization reaction was carried out in the same manner as in Example 1. The styrene monomer unit was 10% by weight, the acrylonitrile monomer unit was 20% by weight, the 1,3-butadiene unit was 70% by weight, and the methyl ethyl ketone insoluble matter was 60%. A weight percent polymer (b6) was obtained. And the nitrile rubber composition was prepared like Example 2 except having used the obtained polymer (b6), and it evaluated similarly. The results are shown in Table 2.

  As can be seen from Table 2, as in Example 2 (repost), Example 3, Example 4, and Example 5, the vinyl monomer unit is 50% by weight or more, and the methyl ethyl ketone insoluble matter is 20% by weight or more. By blending the polymers (b1) to (b4), excellent cold resistance and excellent gasoline permeation resistance could be realized.

On the other hand, in Comparative Example 6 in which the polymer (b5) having a methylethylketone insoluble content of 2% by weight was blended, the gasoline permeation resistance deteriorated and exceeded 600 (g · mm / m ² · day). Oops. Further, even in Comparative Example 7 in which the polymer (b6) having a vinyl monomer unit of less than 50% by weight was blended, the gasoline permeation resistance deteriorated and exceeded 800 (g · mm / m ² · day). It was.

[Comparative Example 8]
In Example 2, a nitrile rubber composition was prepared and evaluated in the same manner as in Example 2 except that the plasticizer (B) was not used. The results are shown in Table 3.

[Comparative Example 9]
Alkyl naphthenic oil (C ₁₀ H ₇ -C _n H _{2n + 1} (n = 16-18) (product name: Barrel Process) having an SP value of 7.8 (cal / cm ³ ) ^1/2 as a plasticizer A nitrile rubber composition was prepared and evaluated in the same manner as in Example 2 except that Oil B-28N (Matsumura Oil Co., Ltd.) was used, and the results are shown in Table 3.

[Comparative Example 10]
The same as in Example 2 except that dimethyl phthalate (product name: DMF, Daihachi Chemical Industry Co., Ltd.) having an SP value of 10.5 (cal / cm ³ ) ^1/2 by the HOY method was used as the plasticizer. A nitrile rubber composition was prepared and evaluated in the same manner. The results are shown in Table 3.

  From Table 3, in Comparative Example 9 in which a plasticizer having an SP value of 7.8 was blended, in addition to having little effect of improving cold resistance, the gasoline permeability resistance was remarkably deteriorated and could not be used. On the other hand, when a plasticizer with SP of 10.5 was blended as in Comparative Example 10, the cold resistance was further deteriorated and the gasoline permeability resistance was also deteriorated. Further, in Comparative Example 8 in which no plasticizer was blended, the cold resistance deteriorated. After all, only when the plasticizer (B) having an SP value of 8.0 to 10.2 was blended (Example 2), it was excellent in both cold resistance and gasoline permeability resistance.

[Example 6]
In Example 1, when the nitrile rubber was produced, the monomer charged for the first stage of the emulsion polymerization was changed to 75.7 parts of acrylonitrile, 22 parts of 1,3-butadiene, and 2.2 parts of 2-vinylpyridine. Each change was made and the first stage reaction was started. When the polymerization conversion ratio with respect to the charged monomer reached 42% by weight and when it reached 60% by weight, 12 parts of 1,3-butadiene were added to the reaction vessel, respectively, in the second and third stages. An eye polymerization reaction was performed. Thereafter, when the polymerization conversion rate with respect to all charged monomers reached 75% by weight, 0.3 part of hydroxylamine sulfate and 0.2 part of potassium hydroxide were added to terminate the polymerization reaction. After the reaction was stopped, the contents of the reaction vessel were heated to 70 ° C., and the unreacted monomer was recovered by steam distillation under reduced pressure to obtain a latex of nitrile rubber (a5) (solid content: 24% by weight). It was.

  When the content ratio of each monomer unit constituting the obtained nitrile rubber (a5) was measured in the same manner as in Production Example 1, 50% by weight of acrylonitrile monomer unit, 2% by weight of 2-vinylpyridine, 1% , 3-butadiene unit was 48% by weight. Moreover, the Mooney viscosity (polymer Mooney viscosity) of the nitrile rubber (a5) was 73, and the methyl ethyl ketone insoluble matter was 0.4% by weight. And the nitrile rubber composition was prepared like Example 1 except having used the obtained nitrile rubber (a5), and it evaluated similarly. The results are shown in Table 4.

[Example 7]
(Manufacture of latex of polyvinyl chloride resin)
A pressure-resistant reaction vessel was charged with 120 parts of water, 0.8 part of sodium lauryl sulfate and 0.06 part of potassium persulfate, and after repeated vacuum degassing twice, 100 parts of vinyl chloride was charged and heated while stirring. The emulsion polymerization was carried out at 47 ° C. After the polymerization conversion reached 90%, it was cooled to room temperature to remove unreacted monomers. The concentration of the obtained polyvinyl chloride resin latex was 41% by weight. The average particle diameter of the polyvinyl chloride resin measured by centrifugal sedimentation turbidity method was 0.3 μm, the average polymerization degree according to JIS K6721 was 1,300, and the glass transition temperature was 80 ° C.

In Example 2, when preparing a nitrile rubber composition, di (butoxyethoxyethyl) adipate as a plasticizer (B) is used for 100 parts in total of the nitrile rubber (a2) and the polymer (b1). The nitrile rubber composition was changed in the same manner as in Example 2 except that the content ratio of was changed to 35 parts and latex of the polyvinyl chloride resin produced above (45 parts as the amount of polyvinyl chloride resin) was further added. I got a thing.
Then, evaluation was performed in the same manner as in Example 2. The results are shown in Table 4.

[Example 8]
(Manufacture of acrylic resin latex)
In a reactor equipped with a thermometer and a stirring device, 150 parts of ion exchange water, 2 parts of sodium octyl sulfate, 0.3 part of ammonium persulfate (polymerization initiator), 80 parts of methyl methacrylate, 20 parts of acrylonitrile and t-dodecyl mercaptan (Molecular weight adjusting agent) 0.05 part was added, emulsion polymerization was started at a temperature of 80 ° C. with stirring, and the reaction was stopped after 5 hours to obtain a latex. The concentration of the obtained acrylic resin latex was 39% by weight, and the polymerization conversion rate was 98% by weight. The average particle diameter of the acrylic resin was 0.2 μm, the number average molecular weight was 600,000, and the glass transition temperature was 103 ° C.

In Example 2, when preparing the nitrile rubber composition, the content of di (butoxyethoxyethyl) adipate as a plasticizer with respect to 100 parts in total of the nitrile rubber (a2) and the polymer (b1) Was changed to 35 parts, and a nitrile rubber composition was obtained in the same manner as in Example 2 except that the latex of the acrylic resin produced above (45 parts as the amount of acrylic resin) was further added.
Then, evaluation was performed in the same manner as in Example 2. The results are shown in Table 4.

[Example 9]
(Production of inorganic filler aqueous dispersion)
As an inorganic filler, 100 parts of purified bentonite (Hojun Co., Ltd., trade name “Bengel”, aspect ratio: 280), which is a plate-like filler, is added to 1995 parts of distilled water in the presence of 5 parts of sodium polyacrylate. Then, the mixture was vigorously stirred to obtain an aqueous inorganic filler dispersion having a solid content concentration of 5%.

  When preparing the nitrile rubber composition, it is obtained as described above so as to be 20 parts of a plate-like filler with respect to 100 parts in total of the nitrile rubber (a2) and the copolymer (b1) (in terms of solid content). An inorganic filler aqueous dispersion was added, and a nitrile rubber composition was obtained in the same manner as in Example 2. Then, evaluation was performed in the same manner as in Example 2. The results are shown in Table 4.

  In Example 6 in which (a5) containing 2-vinylpyridine, which was a cationic monomer, was copolymerized and contained as a component of the nitrile polymer rubber (a), further excellent cold resistance and gasoline permeability were obtained. Could be realized. In Example 7 and Example 8 in which a polyvinyl chloride resin or an acrylic resin was further blended with the polymer component (A), it was possible to achieve even better cold resistance and gasoline permeation resistance. Moreover, in Example 9 which mix | blended the inorganic filler whose aspect-ratio is 30-2,000, it was able to implement | achieved much more excellent cold resistance and gasoline permeability resistance.

[Example 10]
(Manufacture of latex of hydrogenated nitrile rubber (a6))
About the latex of the nitrile rubber (a2) obtained in Example 2, a palladium catalyst (1 wt% palladium acetate / acetone solution) was added to the reactor so that the palladium content was 1000 ppm with respect to the dry rubber weight contained in the latex. And a solution obtained by mixing equal weight of ion-exchanged water) and a hydrogenation reaction was performed at a hydrogen pressure of 3 MPa and a temperature of 50 ° C. for 6 hours to obtain a latex of hydrogenated nitrile rubber (a6).

  When the content ratio of each monomer unit constituting the obtained hydrogenated nitrile rubber (a6) was measured in the same manner as in Production Example 1, 50% by weight of acrylonitrile monomer unit, 1,3-butadiene unit and Total 50% by weight with saturated butadiene units. The hydrogenated nitrile rubber (a6) had a Mooney viscosity (polymer Mooney viscosity) of 155, an iodine value of 20, and a methyl ethyl ketone insoluble content of 0.6% by weight.

  A nitrile rubber composition was prepared and evaluated in the same manner as in Example 2 except that the obtained hydrogenated nitrile rubber (a6) was used. The results are shown in Table 5.

[Comparative Example 11]
In Example 10, the nitrile rubber composition was prepared in the same manner as in Example 2 except that the polymer (b1) was changed to the polymer (b5) having a methylethylketone insoluble content of 2% by weight used in Comparative Example 6. Prepared and evaluated in the same manner. The results are shown in Table 5.

  In Example 10 using the hydrogenated nitrile rubber (a6), extremely excellent cold resistance and gasoline permeation resistance could be realized, but the methyl ethyl ketone insoluble content of the polymer (b) was reduced. In Comparative Example 11 of less than 20% by weight, only cold resistance was poor, although cold resistance was excellent.

  According to the present invention, there are provided a nitrile rubber composition that provides a nitrile rubber crosslinked product excellent in gasoline permeation resistance and cold resistance in addition to the original characteristics of nitrile rubber having good oil resistance, and a crosslinked product thereof. be able to. Therefore, the nitrile rubber composition of the present invention and the cross-linked product thereof can be applied to many fields such as a fuel hose and a fuel seal, and the environment can be reduced by reducing the transpiration amount of fuel such as gasoline into the atmosphere. The load on can be reduced.

Claims (7)

an α, β-ethylenically unsaturated nitrile monomer unit and a conjugated diene monomer unit which may be at least partially hydrogenated, the α, β-ethylenically unsaturated nitrile monomer unit Nitrile rubber (a) having a content of 36 to 54% by weight and an insoluble content of methyl ethyl ketone of less than 20% by weight, and 40 to 95% by weight, and
At least a part of at least one vinyl monomer unit selected from the group consisting of an aromatic vinyl monomer unit and an α, β-ethylenically unsaturated nitrile monomer unit is at least partially hydrogenated. A polymer component (A) containing 60 to 5% by weight of a polymer (b) containing 50 to 0% by weight of a conjugated diene monomer unit and having an insoluble content of methyl ethyl ketone of 20% by weight or more; ,
The SP value by the HOY method is in the range of 8.0 to 10.2 (cal / cm ³ ) ^1/2 at a ratio of 0.1 to 200 parts by weight with respect to 100 parts by weight of the polymer component (A). Plasticizer (B);
A nitrile rubber composition comprising:   The nitrile rubber composition according to claim 1, wherein at least one of the nitrile rubber (a) and the polymer (b) further contains a cationic monomer unit in a proportion of 0 to 30% by weight.   The nitrile rubber composition according to claim 1 or 2, wherein at least one of the nitrile rubber (a) and the polymer (b) is a hydrogenated carbon-carbon unsaturated bond of a conjugated diene monomer unit. .   It contains at least one thermoplastic resin selected from the group consisting of a polyvinyl chloride resin and an acrylic resin in a ratio of 10 to 100 parts by weight with respect to 100 parts by weight of the polymer component (A). The nitrile rubber composition according to any one of claims 1 to 3.   The inorganic filler having an aspect ratio of 30 to 2,000 is contained in a proportion of 1 to 100 parts by weight with respect to 100 parts by weight of the polymer component (A). The nitrile rubber composition according to any one of the above.   A crosslinkable nitrile rubber composition obtained by adding a crosslinking agent to the nitrile rubber composition according to any one of claims 1 to 5.   A crosslinked rubber product obtained by crosslinking the crosslinkable nitrile rubber composition according to claim 6.