JP2006307079A - Polar rubber composition and crosslinked product thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polar rubber composition which has a high affinity to such an adhesive as a phenol resin used for the bonding of a rubber and a metal material and is excellent in the adhesive strength at the time of crosslinking-bonding with a metal material and also is excellent in the permanent compression set resistance after the crosslinking. <P>SOLUTION: The polar rubber composition containing a polar rubber and a petroleum resin is characterized in that the composition has a content of the above petroleum resin of 2-30 parts by weight relative to 100 parts by weight of the above polar rubber. The crosslinked product is obtained by crosslinking this polar rubber composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polar rubber composition and a cross-linked product thereof. More specifically, for example, an adhesive such as a phenol resin is used to provide high adhesive force when cross-bonded to a metal material, and after cross-linking. The present invention relates to a polar rubber composition having excellent compression set resistance and a crosslinked product obtained by crosslinking the polar rubber composition.

  Various rubbers are often used as composite materials with metal materials, fibers, inorganic compounds, plastics, and the like. In particular, a composite material obtained by bonding rubber and a metal material is used as various parts such as metal gaskets, oil seals, and vibration-proof rubbers for automobiles and machine tools.

  Adhesion techniques for manufacturing such rubber and metal composites include, for example, the ebonite method, the cyclized rubber method, the phenol resin method, the halogenated rubber method, the brass plating method, and the electroless plating method. Etc. are known.

  Among these, the phenol resin method is preferably used because the phenol resin used as an adhesive is inexpensive. Such a phenol resin method is usually used for adhesion between a nitrile rubber (NBR) and a metal. Specifically, a metal plate and an uncrosslinked nitrile rubber are laminated through a phenol resin, Next, a cross-linking reaction is performed by heating to obtain a composite material of rubber and metal material (for example, Patent Document 1).

  However, depending on the type of nitrile rubber (NBR), the adhesiveness with a phenol resin as an adhesive is low, and particularly when the nitrile content is low (for example, 33% or less), adhesion failure is likely to occur. There was a problem.

  Therefore, in order to improve the adhesive force between the rubber and the adhesive layer, for example, Patent Documents 2 and 3 disclose an adhesive composition in which an uncrosslinked nitrile rubber is added to a phenol resin as an adhesive. ing. However, in these documents, when the amount of NBR added increases, the adhesive strength with NBR improves, but the viscosity increases, making it difficult to apply, and the strength of adhesion with metal decreases. .

JP 2000-919 A JP 2003-261850 A JP 2003-147314 A

  The present invention was made in view of such a situation, and has high affinity with an adhesive used for bonding a rubber such as a phenolic resin and a metal material, and has excellent adhesion when cross-linked with a metal material, And it aims at providing the polar rubber composition which is excellent in the compression set resistance after bridge | crosslinking. Another object of the present invention is to provide a crosslinked product obtained by crosslinking this polar rubber composition.

  As a result of intensive studies to achieve the above object, the present inventors have found that a novel polar rubber composition containing a specific amount of petroleum resin in a polar rubber uses, for example, an adhesive such as a phenol resin. In this case, the present invention was found to be excellent in adhesiveness with a metal material, and that the obtained cross-linked product was excellent in compression set resistance. Based on this finding, the present invention was completed.

That is, the polar rubber composition according to the present invention is
A polar rubber composition comprising a polar rubber and a petroleum resin,
The content of the petroleum resin is 2 to 30 parts by weight with respect to 100 parts by weight of the polar rubber.

In the polar rubber composition of the present invention, preferably, the petroleum resin is at least one selected from an aliphatic petroleum resin, an aromatic / aliphatic copolymer petroleum resin, and an alicyclic petroleum resin.
In the polar rubber composition of the present invention, preferably, the aliphatic petroleum resin, aromatic / aliphatic copolymer petroleum resin and alicyclic petroleum resin have a reactive functional group.
The polar rubber composition of the present invention is preferably at least one of ethylenically unsaturated nitrile conjugated diene copolymer rubber and acrylic rubber.
The crosslinked product of the present invention is a crosslinked product obtained by crosslinking one of the polar rubber compositions described above.

  Since the polar rubber composition of the present invention contains a polar rubber and a specific amount of petroleum resin, it has high adhesion when it is cross-linked with a metal material via an adhesive such as a phenol resin. And has excellent compression set resistance. Therefore, for example, it can be suitably used for a composite material of rubber and a metal material used as a metal gasket, oil seal, anti-vibration rubber or the like for automobiles or machine tools.

  In particular, in the present invention, the affinity with an adhesive such as a phenol resin can be increased by including a specific amount of petroleum resin in the polar rubber. Therefore, it is possible to effectively prevent the occurrence of peeling between the rubber and the adhesive layer, which has been a problem in the past.

Polar rubber composition The polar rubber composition of the present invention is a composition comprising at least a polar rubber and a petroleum resin.
The content of the petroleum resin is 2 to 30 parts by weight, preferably 3 to 25 parts by weight, and more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the polar rubber. If the content of the petroleum resin in the polar rubber composition is too small, the adhesiveness when crosslinked and bonded tends to decrease. On the other hand, if the amount is too large, the compression set resistance tends to decrease.
Hereinafter, the polar rubber and petroleum resin contained in the polar rubber composition of the present invention will be described.

The polar rubber is not particularly limited, and various rubbers can be used. In addition to carbon (C) and hydrogen (H), the molecular structure includes nitrogen (N), oxygen (O), sulfur ( A rubber having a polar group containing atoms such as S), halogen (F, Cl, Br, etc.), phosphorus (P), etc. is preferred. Examples of such polar rubber include ethylenically unsaturated nitrile-conjugated diene copolymer rubber, acrylic rubber (ACM, ANM), chloroprene rubber (CR), chlorosulfonated polyethylene (CSM), epichlorohydrin rubber ( ECO, CHC), chlorinated polyethylene (CM), polysulfide rubber (T), fluororubber (FKM), hydrogenated ethylenically unsaturated nitrile-conjugated diene rubber and the like. These may be used alone or in combination of two or more.

  The polar rubber used in the present invention preferably has a number average molecular weight in the range of 5,000 to 2,000,000, more preferably in the range of 10,000 to 500,000. If the number average molecular weight is too small, the strength properties of the rubber may be inferior. On the other hand, if it is too large, the moldability tends to be inferior, and in some cases, it tends to be impossible to mold.

Moreover, Mooney viscosity (ML1 _{+ 4} , 100 degreeC) becomes like this. Preferably it is 10-200, More preferably, it is 20-150. If the Mooney viscosity is too low, the strength properties of the rubber may be inferior. On the other hand, when too high, the handleability in an uncrosslinked state will deteriorate, and workability and moldability may be inferior.

  Among these, ethylenically unsaturated nitrile-conjugated diene copolymer rubber and acrylic rubber (ACM) are particularly preferred because of their high polarity and excellent adhesiveness.

  Ethylenically unsaturated nitrile-conjugated diene copolymer rubber (hereinafter referred to as “nitrile rubber” as appropriate) is a conjugated diene, an ethylenically unsaturated nitrile, and other copolymerizable with these. It is a polymer obtained by copolymerizing a monomer.

As said conjugated diene, a C4-C12 aliphatic conjugated diene compound is mentioned, for example.
Specific examples include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, halogen-substituted butadiene, and the like. Is preferred. These can be used individually by 1 type or in combination of 2 or more types.

As said ethylenically unsaturated nitrile, the C3-C18 ethylenically unsaturated compound which has a nitrile group is mentioned, for example.
Specific examples include acrylonitrile, methacrylonitrile, halogen-substituted acrylonitrile and the like, and acrylonitrile is particularly preferable. These can be used individually by 1 type or in combination of 2 or more types.

  The content of the ethylenically unsaturated nitrile monomer unit in the nitrile rubber is preferably 10 to 80% by weight, more preferably 20 to 60% by weight. When there is too little content of an ethylenically unsaturated nitrile monomer unit, there exists a possibility that polarity may become low. On the other hand, if the amount is too large, the flexibility of the rubber may be reduced.

  Examples of other copolymerizable monomers used as necessary include ethylenically unsaturated carboxylic acid, non-conjugated diene, α-olefin, aromatic vinyl, ethylenically unsaturated monocarboxylic acid ester, fluoroolefin, Examples include ethylenically unsaturated carboxylic acid amides.

Examples of the ethylenically unsaturated carboxylic acid include C3-C18 carboxyl group-containing ethylenically unsaturated compounds.
Specific examples include ethylenically unsaturated monocarboxylic acids, ethylenically unsaturated polyvalent carboxylic acids, and ethylenically unsaturated polyvalent carboxylic acid partial esters.

Examples of the ethylenically unsaturated monocarboxylic acid include acrylic acid, methacrylic acid, ethyl acrylic acid, crotonic acid, and cinnamic acid.
Examples of the ethylenically unsaturated polyvalent carboxylic acid include maleic acid, fumaric acid, itaconic acid, citraconic acid, and chloromaleic acid.
Examples of the ethylenically unsaturated polyvalent carboxylic acid partial ester include monomethyl maleate, monoethyl maleate, monobutyl maleate, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, mono-2-hydroxyethyl fumarate, monomethyl itaconate, Examples thereof include monoethyl itaconate and monobutyl itaconate.

  Non-conjugated dienes include non-conjugated dienes having 5 to 12 carbon atoms, and specific examples include 1,4-pentadiene, 1,4-hexadiene, vinylnorbornene, and dicyclopentadiene.

  The α-olefin is a chain monoolefin having a double bond between a terminal carbon of a hydrocarbon having 2 to 12 carbon atoms and a carbon adjacent thereto, ethylene, propylene, 1-butene, 4-methyl- Examples include 1-pentene, 1-hexene, 1-octene and the like.

  Examples of the aromatic vinyl include styrene and styrene derivatives having 8 to 18 carbon atoms, and examples of the derivatives include α-methylstyrene, vinyltoluene and the like.

  The ethylenically unsaturated monocarboxylic acid ester is an ester of an ethylenically unsaturated monocarboxylic acid and an aliphatic alcohol having 1 to 12 carbon atoms. Methyl (meth) acrylate [meaning methyl methacrylate and methyl acrylate. The same applies to (meth) acrylamide hereinafter. ], Butyl (meth) acrylate, methoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, and the like.

  The fluoroolefin is an unsaturated fluorinated compound having 2 to 12 carbon atoms, and examples thereof include difluoroethylene, tetrafluoroethylene, fluoroethyl vinyl ether, fluoropropyl vinyl ether, o-trifluoromethylstyrene, and pentafluorovinyl vinylate.

  Examples of the ethylenically unsaturated carboxylic acid amide include (meth) acrylamide and N-methylol (meth) acrylamide.

  Nitrile rubber is obtained by performing a polymerization reaction by a known emulsion polymerization method using the above conjugated diene, ethylenically unsaturated nitrile, ethylenically unsaturated carboxylic acid and other monomers used as necessary. be able to.

The nitrile rubber used in the present invention preferably has a number average molecular weight in the range of 10,000 to 1,000,000, and has a Mooney viscosity (ML _{1 + 4} , 100 ° C.) in the range of 20 to 150. preferable.

  Acrylic rubber (ACM, ANM) means (meth) acrylic acid ester monomer [acrylic acid ester monomer or / and methacrylic acid ester monomer in the molecule. The same applies to methyl (meth) acrylate. ] A polymer containing units. The content of the (meth) acrylic acid ester monomer is preferably 80% by weight or more, more preferably 90% by weight or more, and still more preferably 95% by weight or more.

  Examples of (meth) acrylic acid ester monomers include (meth) acrylic acid alkyl ester monomers and (meth) acrylic acid alkoxyalkyl ester monomers.

  The (meth) acrylic acid alkyl ester monomer is preferably an ester of an alkanol having 1 to 8 carbon atoms and (meth) acrylic acid, specifically, methyl (meth) acrylate or ethyl (meth) acrylate. , N-propyl (meth) acrylate, n-butyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate And cyclohexyl (meth) acrylate. Of these, ethyl (meth) acrylate and n-butyl (meth) acrylate are preferred.

  The (meth) acrylic acid alkoxyalkyl ester monomer is preferably an ester of an alkoxyalkanol having 2 to 8 carbon atoms and (meth) acrylic acid, specifically, methoxymethyl (meth) acrylate, (meth) Ethoxymethyl acrylate, 2-ethoxyethyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-propoxyethyl (meth) acrylate, (meth) acrylic acid Examples include 3-methoxypropyl and 4-methoxybutyl (meth) acrylate. Among these, 2-ethoxyethyl (meth) acrylate and 2-methoxyethyl (meth) acrylate are particularly preferable, 2-ethoxyethyl acrylate and 2-methoxyethyl acrylate.

  Moreover, the acrylic rubber may contain a monomer unit copolymerizable with the (meth) acrylic acid ester monomer. Examples of such copolymerizable monomer units include aromatic vinyl monomers, α, β-ethylenically unsaturated nitrile monomers, and monomers having two or more acryloyloxy groups (polyfunctional acrylic monomers). And olefin monomers other than these, monomers having a crosslinkable group such as a carboxyl group, a halogen atom, an epoxy group or a hydroxyl group, and a diene monomer.

  The acrylic rubber can be obtained by performing a polymerization reaction by a known emulsion polymerization method using the (meth) acrylic acid ester monomer and a monomer copolymerizable therewith.

The acrylic rubber used in the present invention preferably has a number average molecular weight in the range of 10,000 to 100,000, and has a Mooney viscosity (ML _{1 + 4} , 100 ° C.) in the range of 20 to 150. preferable.

Petroleum resin The polar resin constituting the polar rubber composition of the present invention may be at least one selected from aliphatic petroleum resins, aromatic / aliphatic copolymer petroleum resins and alicyclic petroleum resins. An aromatic / aliphatic copolymer petroleum resin or an alicyclic petroleum resin is more preferable.

The above-mentioned aliphatic petroleum resin is mainly composed of olefin / diolefin having 4 to 6 carbon atoms such as isoprene, piperylene, 2-methylbutene-1 among cracked oil fractions by-produced from an ethylene plant by petroleum steam cracking. In the present invention, those using piperylene as the main raw material are particularly preferred.
The aromatic / aliphatic copolymer petroleum resin can be obtained by copolymerizing the olefin / diolefin having 4 to 6 carbon atoms and the aromatic unit having 8 to 11 carbon atoms. Examples of such aromatic units having 8 to 11 carbon atoms include styrene, vinyltoluene, α-methylstyrene, indene, and methylindene.
The alicyclic petroleum resin can be obtained by polymerizing a cyclopentadiene monomer as a main component. Specific examples of cyclopentadiene monomers include cyclopentadiene; alkyl-substituted products of cyclopentadiene such as methylcyclopentadiene and ethylcyclopentadiene; cyclopentadiene such as dicyclopentadiene, tricyclopentadiene and methyldicyclopentadiene or alkyl thereof. Multimers of substitutions are exemplified.
The aliphatic petroleum resin, aromatic / aliphatic copolymer petroleum resin, and alicyclic petroleum resin may be hydrogenated hydrogenated products.

  It is more preferable that the aliphatic petroleum resin, aromatic / aliphatic copolymer petroleum resin, and alicyclic petroleum resin each have a reactive functional group. That is, a functional group-containing aliphatic petroleum resin, a functional group-containing aromatic / aliphatic copolymer petroleum resin, and a functional group-containing alicyclic petroleum resin are more preferable. By having a reactive functional group, the adhesive strength at the time of cross-linking adhesion can be improved.

  Such functional group-containing aliphatic petroleum resins, functional group-containing aromatic / aliphatic copolymer petroleum resins, functional group-containing alicyclic petroleum resins, for example, using acids and acid anhydrides, It can be obtained by modifying an aliphatic petroleum resin, an aromatic / aliphatic copolymer petroleum resin or an alicyclic petroleum resin, or by copolymerizing these petroleum resins. Examples of the reactive functional group include a hydroxyl group, an acid anhydride group, a carboxyl group, a halogen group, an epoxy group, a vinyl group, an isocyanate group, a mercapto group, an amino group, and an ester group. Among these, it is particularly preferable that an acid anhydride group, a carboxyl group, or a hydroxyl group is contained. The content of such a reactive functional group is not particularly limited, but in the case of an acid anhydride group or a carboxyl group, the acid value is preferably 0.1 to 100 mg · KOH / g, more preferably 0.5 to 50 mg. -KOH / g. In the case of a hydroxyl group, the hydroxyl value is preferably 40 to 400 mg · KOH / g, more preferably 60 to 300 mg · KOH / g.

The petroleum resin used in the present invention preferably has a number average molecular weight (Mn) in the range of 200 to 5000, more preferably in the range of 300 to 3000. If the molecular weight is too small, the adhesive force tends to decrease. On the other hand, if it is too large, dispersion tends to be poor when kneaded with rubber.
Moreover, it is preferable that a softening point is the range of 60 to 170 degreeC, More preferably, it is 70 to 150 degreeC. If the softening point is too low, stickiness and handleability tend to be poor when kneaded into rubber, and if the softening point is too high, melting tends to be difficult, resulting in poor dispersion.

Crosslinking agent The polar rubber composition of the present invention can be made into a crosslinkable rubber composition by further containing a crosslinking agent.
Such a crosslinking agent is not particularly limited, and various commonly used crosslinking agents suitable for each rubber can be used. When nitrile rubber is used, in the present invention, it is preferable to use a sulfur-based crosslinking agent as the crosslinking agent. Examples of such a sulfur-based crosslinking agent include sulfur or a sulfur donor.

Specifically, examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.
The sulfur donor includes disulfide compounds such as morpholine disulfide and tetramethylthiuram disulfide, polysulfides such as dipentamethylenethiuram tetrasulfide, poly (ethylene tetrasulfide), poly (propylene tetrasulfide), poly ( Polymer polysulfides such as tetraethylene sulfide), N, N′-dithiodi (polymethyleneimine), N, N′-bis (2-benzothiazoylthio) piperazine, and the like.

  The content of the crosslinking agent in the polar rubber composition of the present invention is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 3 parts by weight with respect to 100 parts by weight of the polar rubber. When there is too little content of a crosslinking agent, bridge | crosslinking may become inadequate and there exists a possibility that it may become difficult to maintain the shape of a crosslinked material. On the other hand, if the amount is too large, the cross-linked product becomes too hard, and the elasticity as a cross-linked rubber may be impaired.

Other Additives The polar rubber composition of the present invention may contain other crosslinking accelerators, crosslinking accelerators, reinforcing agents, processing aids, light stabilizers, plasticizers, lubricants, pressure-sensitive adhesives, lubricants, difficulty, etc. You may contain additives, such as a flame retardant, an antifungal agent, an antistatic agent, a coloring agent, and a filler.

  The crosslinking accelerator may be selected from those suitable for each rubber, and is not particularly limited. However, when a nitrile rubber is used, guanidine, aldehyde-amine, aldehyde-ammonia, thiazole, thiuram , Sulfenamide-based and thiourea-based compounds; alkali metal salts of weak acids, and the like. Among these, thiazole compounds, thiuram compounds, and alkali metal salts of weak acids can be preferably used. These can be used alone or in combination of two or more.

  Examples of thiazole compounds include 2-mercaptobenzothiazole, 2-mercaptobenzothiazole zinc salt, 2-mercaptobenzothiazole-cyclohexylamine salt, dibenzothiazyl disulfide, and the like.

Examples of thiuram compounds include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, and the like.
Examples of the weak metal alkali metal salts include inorganic weak acid salts such as sodium or potassium phosphates and carbonates, or organic weak acid salts such as stearates and laurates.

  The amount of the crosslinking accelerator used is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 3 parts by weight with respect to 100 parts by weight of the polar rubber. When there are too many crosslinking accelerators, there is a possibility that the crosslinking rate becomes too fast at the time of crosslinking, the crosslinking accelerator blooms on the surface of the crosslinked product, or the crosslinked product becomes too hard. When there are too few crosslinking accelerators, the tensile strength of a crosslinked material may fall remarkably.

  In the present invention, in addition to the crosslinking accelerator, a crosslinking acceleration assistant may be used. The crosslinking accelerator aid is added to activate the crosslinking accelerator and further accelerate the reaction. Examples of the crosslinking accelerating aid include metal oxides such as zinc oxide and fatty acids such as stearic acid.

  As a method for preparing the polar rubber composition of the present invention, polar rubber, petroleum resin, and additives used as necessary are mixed by an appropriate method such as roll mixing, Banbury mixing, screw mixing, solution mixing and the like. The method can be adopted. The order of blending is not particularly limited. However, after sufficiently mixing components that are not easily reacted or decomposed by heat, components that are easily reacted by heat or components that are easily decomposed, such as crosslinking agents and crosslinking accelerators, are not reacted or decomposed. What is necessary is just to mix for a short time at the temperature which is not.

Cross-linked product The cross-linked product of the present invention is obtained by molding and crosslinking the above-described polar rubber composition of the present invention at a high temperature and high pressure by a molding method such as extrusion molding, injection molding, transfer molding or compression molding. Obtainable.

When the cross-linked product of the present invention is cross-linked and adhered to a metal material through an adhesive layer such as a phenol resin to form a composite material of rubber and metal material, for example, the following method may be employed.
That is, first, a metal plate that has been roughened by shot blasting, scotch bride, hairline, dull finish or the like is prepared. Although it does not specifically limit as a metal plate, A stainless steel plate, a copper plate, an aluminum plate etc. can be used.

  Next, an adhesive layer is formed on the roughened metal plate. Examples of the adhesive for forming the adhesive layer include a phenol resin, and specifically, a novolac type phenol resin or a resol type phenol resin is preferably used, and contains a curing agent as necessary. You may do it. These phenolic resins are applied onto a metal material by a brush coating method, a dipping method, a spray method, a spray method, a roll coater method, or the like in a state diluted with a solvent such as ethanol. Then, after drying at room temperature or warm air, if necessary, it is baked at a temperature of 100 to 250 ° C. for 10 to 30 minutes to form an adhesive layer.

  Next, an uncrosslinked molded body formed into a sheet shape is formed on a metal material via an adhesive layer to obtain a laminate. And the obtained laminated body is heated and compressed with a compression molding machine, whereby the molded body is crosslinked and bonded, and a composite material of a crosslinked polar rubber and a metal material can be obtained.

  The cross-linked product of the present invention is a cross-linked product obtained by cross-linking a polar rubber composition containing a polar rubber and a petroleum resin, and in particular, an adhesive used for bonding a rubber such as a phenol resin and a metal material. It has high affinity with the agent, excellent adhesion when bonded to a metal material, and high compression set resistance. Therefore, by using the cross-linked polar rubber of the present invention as a composite material with a metal material, it can be suitably used, for example, as a metal gasket, oil seal, anti-vibration rubber or the like for automobiles or machine tools.

  The present invention will be specifically described below with reference to examples and comparative examples. [Part] and [%] in these examples are based on weight unless otherwise specified. However, the present invention is not limited only to these examples. In addition, each obtained sample was evaluated by the following method.

Metal Adhesive As a sample for evaluating metal adhesiveness, a laminate sample in which rubber (cross-linked product) and a metal plate were bonded was produced by the following method.
That is, first, a 3 mm × 25 mm × 60 mm metal plate (JIS G 3141 SPCCSD) was prepared, and the surface of the metal plate was roughened by using 320 mesh sandpaper to roughen the surface of the metal plate. Was washed using toluene and acetone. Next, a 25% ethanol solution of phenolic resin (adhesive, product number RM-1 manufactured by Qingdao Yashiko Kogyo Co., Ltd.) was applied to the surface of the roughened metal plate, allowed to stand for 30 minutes and air-dried. Then, an oven was heated in an oven at a temperature of 150 ° C. for 20 minutes to perform a baking treatment to form an adhesive layer.

  Next, a 2.5 mm × 25 mm × 125 mm uncrosslinked rubber composition sheet was placed on the metal plate on which the adhesive layer was formed to obtain a laminate before crosslinking. And this laminated body before bridge | crosslinking is put into a 5 mm x 25 mm x 125 mm metal mold | die, pressure 12MPa, temperature 160 degreeC, 20 minutes (however, as for Example 2, temperature 170 degreeC, 20 minutes) The rubber composition was subjected to a crosslinking reaction to obtain a laminate sample for metal adhesion test (the contact area between the rubber and the metal plate was 25 mm × 60 mm).

  Using the laminate sample prepared above, a 90 degree peel test was performed in accordance with JIS K 6256, and the 90 degree peel strength and the breakage rate of the rubber part of the peel failure were evaluated to evaluate the metal adhesion. . It is preferable that the 90 degree peel strength and the breakage rate of the peeled rubber part are higher. In this example, the 90 degree peel strength is preferably 7 N / mm or more, more preferably 8 N / mm or more. The breakage ratio of the part is preferably 70% or more, more preferably 80% or more.

Compression set resistance First, a sheet of an uncrosslinked rubber composition was punched into a circle, and a plurality of the obtained circular rubber compositions were stacked to form a cylindrical shape having a diameter of 29 mm and a height of 12.5 mm. Next, this cylindrical rubber composition is placed in an oven and heated under the conditions of a temperature of 160 ° C. and 20 minutes (however, in Example 2, the temperature is 170 ° C. and 20 minutes), whereby a cylindrical crosslinked product is obtained. Was made. Then, according to JIS K 6262, after the obtained crosslinked product was compressed by 25% and placed in an environment of 120 ° C. for 70 hours, the compression was released and the compression set was measured. The compression set rate is better as the numerical value is smaller and the material is more difficult to deform.

Example 1
Nitrile rubber (Nipol DN2850, Nippon Zeon Co., Ltd., Mooney viscosity (ML _{1 + 4} , 100 ° C.) 50, nitrile content 28%): 100 parts by weight, zinc white: 5 parts by weight, stearic acid: 1 part by weight, phthalic acid Dioctyl (plasticizer): 5 parts by weight, carbon black (FEF carbon, SEAST SO manufactured by Tokai Carbon Co., Ltd.): 60 parts by weight, aromatic / aliphatic copolymer petroleum resin (Quinton U190 manufactured by Nippon Zeon Co., Ltd.) : 10 parts by weight was kneaded using a 1.7 L Banbury mixer. Subsequently, 1.5 parts by weight of sulfur as a crosslinking agent, 1.5 parts by weight of dibenzothiazyl disulfide as a crosslinking accelerator, and 0.4 parts by weight of tetramethylthiuram monosulfide are added to the kneaded material obtained. And the sheet | seat of the uncrosslinked rubber composition was manufactured with the 8-inch roll.

  The petroleum resin used in this example (Quinton U190 manufactured by Nippon Zeon Co., Ltd.) is an aromatic / aliphatic copolymer petroleum resin having a number average molecular weight of 1,000 and a softening point of 89 ° C.

  Next, using the obtained sheet-like rubber composition, a metal adhesion test and a compression set test were respectively performed according to the above methods. The results are shown in Table 1.

Example 2
Instead of nitrile rubber, the same amount of acrylic rubber (Nipol AR72LS, Mooney viscosity (ML _{1 + 4} , 100 ° C.) 33, manufactured by Nippon Zeon Co., Ltd.) 33, sulfur: 1.5 parts by weight as a crosslinking agent and crosslinking accelerator, Instead of 1.5 parts by weight dibenzothiazyl disulfide and 0.4 parts by weight tetramethylthiuram monosulfide: 0.3 parts by weight sulfur, 3 parts by weight sodium stearate, 0.5 parts by weight potassium stearate An uncrosslinked rubber composition sheet was produced in the same manner as in Example 1 except that the parts were used. And using the obtained sheet-like rubber composition, according to said method, the metal-adhesion test and the compression set test were done, respectively. The results are shown in Table 1.

Examples 3 and 4
Uncrosslinked in the same manner as in Example 1, except that the content of the aromatic / aliphatic copolymer petroleum resin was changed to 5 parts by weight (Example 3) and 20 parts by weight (Example 4), respectively. A sheet of the rubber composition was produced and subjected to a metal adhesion test and a compression set test, respectively. The results are shown in Table 1.

Example 5
An uncrosslinked rubber composition in the same manner as in Example 1 except that a modified alicyclic petroleum resin (Quinton 1700 manufactured by Nippon Zeon Co., Ltd.) was used instead of the aromatic / aliphatic copolymer petroleum resin. The sheet | seat of the thing was manufactured and the metal-adhesion test and the compression set test were done, respectively. The results are shown in Table 1. The modified alicyclic petroleum resin (Quinton 1700) used in this example has a number average molecular weight of 380, a hydroxyl value of 220 mg · KOH / g, and a hydroxyl group-containing alicyclic petroleum resin having a softening point of 100 ° C. It is.

Example 6
In the same manner as in Example 1, except that an acid-modified aromatic / aliphatic copolymer petroleum resin (Quinton D200 manufactured by Nippon Zeon Co., Ltd.) was used instead of the aromatic / aliphatic copolymer petroleum resin, A sheet of an uncrosslinked rubber composition was produced and subjected to a metal adhesion test and a compression set test, respectively. The results are shown in Table 1. The quinton D200 used in this example is an acid-modified aromatic / aliphatic copolymer petroleum resin having a number average molecular weight of 1,250, an acid value of 17.0 mg · KOH / g, and a softening point of 102 ° C. is there.

Comparative Example 1
Instead of nitrile rubber, the same amount of styrene butadiene rubber (Nipol 1502, manufactured by Nippon Zeon Co., Ltd., Mooney viscosity (ML _{1 + 4} , 100 ° C.) 52), instead of dioctyl phthalate, the same amount of naphthenic oil, Except for the use, a sheet of an uncrosslinked rubber composition was produced in the same manner as in Example 1, and a metal adhesion test and a compression set test were performed. The results are shown in Table 1.

Comparative Example 2
Example 1 except that the same amount of coumarone-indene resin (manufactured by Nippon Steel Chemical Co., Ltd., product number coumarone G90: softening point 90 ° C.) was used instead of the aromatic / aliphatic copolymer petroleum resin. Thus, a sheet of an uncrosslinked rubber composition was produced, and a metal adhesion test and a compression set test were performed, respectively. The results are shown in Table 1.

Comparative Example 3
A sheet of an uncrosslinked rubber composition was produced in the same manner as in Example 1 except that the content of the aromatic / aliphatic copolymer petroleum resin was changed to 50 parts by weight, and a metal adhesion test and compression were performed. Each permanent set test was performed. The results are shown in Table 1.

  From Table 1, Examples 1-6 which used polar rubber composition containing polar rubber and a predetermined amount of petroleum resin are excellent in metal adhesiveness and compression set resistance, and from rubber and a metal material. It was confirmed that the composite material was suitable.

  On the other hand, in the comparative example 1 which uses the styrene butadiene rubber which is a nonpolar rubber instead of a polar rubber, it resulted in inferior to adhesiveness.

Further, in Comparative Example 2 in which a coumarone-indene resin was used instead of the petroleum resin, the adhesiveness was similarly inferior.
Furthermore, in Comparative Example 3 in which the content of the aromatic / aliphatic copolymer petroleum resin was 50 parts by weight outside the scope of the present invention, the adhesiveness could be secured, but the results were inferior in compression set resistance. became.

Claims (5)

A polar rubber composition comprising a polar rubber and a petroleum resin,
The polar rubber composition whose content of the said petroleum resin is 2-30 weight part with respect to 100 weight part of said polar rubbers.   The polar rubber composition according to claim 1, wherein the petroleum resin is at least one selected from an aliphatic petroleum resin, an aromatic / aliphatic copolymer petroleum resin, and an alicyclic petroleum resin.   The polar rubber composition according to claim 2, wherein the aliphatic petroleum resin, the aromatic / aliphatic copolymer petroleum resin, and the alicyclic petroleum resin have a reactive functional group.   The polar rubber composition according to claim 1, wherein the polar rubber is at least one of an ethylenically unsaturated nitrile-conjugated diene copolymer rubber and an acrylic rubber.   A cross-linked product obtained by cross-linking the polar rubber composition according to claim 1.