JP2001240680A - Method for compounding rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for compounding a rubber composition, capable of stabilizing adhesion development of the rubber composition having high adhesiveness a metal, a high modulus, a high setting resistance and a high heat resistance. SOLUTION: This method for compounding a rubber composition comprises compounding the rubber composition containing 1-100 mass pts. of a raw material rubber crosslinkable with an organic peroxide, 1-100 mass pts. of a polymer containing an organic peroxide crosslinkable epoxy group, 1-10 mass pts. of an organic peroxide and 0.1-15 mass pts. of a 2,4-dimercapto-6-substituted-1,3,5- triazine of the following formula 1 (R is a group selected from the group consisting of a mercapto group, an alkoxy group, a monoalkylamino group, a dialkylamino group, a monocycloalkylamino group, a dicycloalkylamino group and an N-alkyl-N-arylamino group) maintaining the rubber composition at <=140 deg.C throughout the whole process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mixing a rubber composition having high adhesion to metal and excellent heat resistance.

[0002]

2. Description of the Related Art Non-diene rubbers are widely used because of their excellent heat resistance. Non-diene rubber is
In use, it is necessary to crosslink with an organic peroxide, and sulfur having good adhesion to metal cannot be used as a crosslinking agent. Therefore, it is extremely difficult to bond non-diene rubber directly to metal, and a composite of rubber and metal such as hose, belt, tire, roll, and mold, for example, rubber combined with brass-plated steel plate or steel wire Many studies have been made on formulas that exhibit adhesiveness when used in products. The present inventors have conducted intensive studies and as a result,
Organic peroxide crosslinkable raw material rubber, organic peroxide crosslinkable polymer having epoxy group, organic peroxide, and 2,4-dimercapto-6-substituted compound represented by the following formula 1
A rubber composition containing 1,3,5-triazine has been proposed.

[0003]

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(Wherein R is selected from the group consisting of mercapto, alkoxy, monoalkylamino, dialkylamino, monocycloalkylamino, dicycloalkylamino and N-alkyl-N-arylamino groups. However, the rubber composition is excellent in adhesiveness to a copper-containing metal such as brass (brass) and bronze, but is not sufficiently stable in adhesiveness. . Specifically, there has been no known technique for constantly expressing a certain or more adhesive force.

[0005]

DISCLOSURE OF THE INVENTION The present invention has high adhesiveness to metal, and has high modulus, high set resistance and high heat resistance. Therefore, the present invention relates to rubber for hoses, belts, tires, rolls, molds and the like. It is an object of the present invention to provide a method of mixing a rubber composition which can stably exhibit adhesion of a rubber composition which can be suitably used for a metal composite.

[0006]

That is, the present invention relates to an organic peroxide-crosslinkable raw material rubber of 100 parts by mass, an organic peroxide-crosslinkable epoxy-group-containing polymer having 1 to 100 parts by mass, an organic peroxide. A method for mixing a rubber composition containing 1 to 10 parts by mass and 0.1 to 15 parts by mass of 2,4-dimercapto-6-substituted-1,3,5-triazine represented by the following formula 1, Provided is a method for mixing a rubber composition, which maintains the temperature of the rubber composition at 140 ° C. or lower throughout the entire process.

[0007]

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Wherein R is selected from the group consisting of mercapto, alkoxy, monoalkylamino, dialkylamino, monocycloalkylamino, dicycloalkylamino, and N-alkyl-N-arylamino groups. Represents a group represented by

The 2,4-dimercapto-6-substituted-
It is preferable to maintain the temperature of the rubber composition in a step after the addition of 1,3,5-triazine at 100 ° C. or lower.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The present invention is characterized in that by maintaining the temperature at the time of mixing the rubber composition in a certain range, the adhesiveness can be stably obtained. Here, that the adhesiveness is stable means that there is little variation in adhesiveness when the rubber composition is cured.

First, the rubber composition will be described. The raw rubber used in the rubber composition is not particularly limited as long as it can be crosslinked by an organic peroxide.
Both diene rubber and non-diene rubber are used.

The organic peroxide crosslinkable diene rubber is
For example, natural rubber, isoprene rubber, chloroprene rubber, styrene-butadiene copolymer rubber, butadiene rubber (high cis-butadiene rubber, low cis-butadiene rubber), halogen-containing rubber (for example, brominated butyl rubber, chlorinated butyl rubber), acrylonitrile-butadiene And copolymer rubber (NBR).

Non-diene rubbers that can be crosslinked with an organic peroxide include, for example, hydrogenated acrylonitrile-butadiene copolymer rubber (HNBR), hydrogenated styrene-butadiene copolymer rubber, and olefin-based rubber (eg, ethylene-propylene copolymer). Rubber (EPM), ethylene-propylene-diene copolymer rubber (EPDM)), ethylene-acrylate copolymer rubber (AEM) (for example, ethylene-methyl acrylate copolymer rubber, ethylene-ethyl acrylate copolymer rubber, Ethylene-methyl methacrylate copolymer rubber), ionomer, halogen-containing rubber (for example, bromide of isobutylene-paramethylstyrene copolymer, chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene rubber (CM)), silicone rubber (For example, methyl vinyl silicone Rubber, methylphenylvinyl silicone rubber), fluorine rubber (e.g., vinylidene fluoride rubbers, fluorine-containing vinyl ether rubbers, fluorine-containing phosphazene rubber), and the like. Above all, H
NBR, AEM, EPM, EPDM are preferred.

The polymer having an epoxy group used in the rubber composition can be crosslinked with an organic peroxide. Since epoxy resin such as bisphenol A type hardly cross-links with organic peroxide,
It is not included in the epoxy group-containing polymer used in the rubber composition. When an epoxy resin is used instead of the polymer having an epoxy group used in the rubber composition, the bonding between the rubber composition and the metal is insufficient because the bonding with the raw rubber is small. The content of the polymer having an epoxy group in the rubber composition is generally 1 to 100 parts by mass, preferably 5 to 50 parts by mass with respect to 100 parts by mass of the raw rubber, though it depends on the amount of the epoxy group having the same. . If the amount is less than 1 part by mass, the adhesion between the rubber composition and the metal may be insufficient. If it exceeds 100 parts by mass, the adhesion between the rubber composition and the metal and the heat resistance may be reduced. When the amount is 5 to 50 parts by mass, the balance between the adhesion between the rubber composition and the metal, the tensile stress (modulus), the set resistance (compression set resistance), and the heat resistance becomes better.

The polymer having an epoxy group used in the rubber composition is not particularly limited as long as it reacts with the raw rubber by an organic peroxide. In consideration of the adhesiveness between the rubber composition and the metal, a preferred example of the polymer having an epoxy group is a graft copolymer, in which the main chain is crosslinkable by a raw rubber and an organic peroxide, At least one of them has an epoxy group.

The main chain of the graft copolymer is not particularly limited, but is preferably an ethylene polymer. Ethylene-based polymers include, for example, low density polyethylene (LDPE),
Ethylene-vinyl acetate copolymer resin (EVA), ethylene-acrylate copolymer (for example, ethylene-
Methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl methacrylate copolymer (EMMA)), ethylene-propylene copolymer (EPM), and polypropylene (PP) No. Glycidyl methacrylate (GMA) or the like is preferably used as the graft chain monomer. The main chain and the graft chain may each be obtained from one type of monomer, or may be obtained from two or more types of monomers. The graft copolymer has a structure in which the graft chain is branched and bonded to the main chain, and the main chain and the raw rubber are crosslinked, and the epoxy group which is the graft chain is 2,4- Dimercapto-6-substituted-1,3,5
-It is considered that it reacts with triazine and adheres the raw rubber and the metal via the graft copolymer. Preferred examples of the combination of the raw rubber and the polymer having an epoxy group, which is a graft copolymer, include CM and EMA-g-GMA (graft copolymer having a main chain of EMA and a graft chain of GMA), EPM and EMA- g-GMA, AEM and EMA-
g-GMA, NBR and EMA-g-GMA, HNBR and EMA-g-GMA, EPDM and EMA-g-GMA.

Further, when the raw rubber is a polymer having an epoxy group, for example, an ethylene-acrylate-glycidyl methacrylate copolymer rubber, the raw rubber itself is a polymer having an epoxy group. It can be suitably used without adding a polymer having an epoxy group.

The organic peroxide used in the rubber composition functions as a crosslinking agent for the raw rubber and the polymer having an epoxy group. The organic peroxide is not particularly limited as long as it is generally used for rubber cross-linking, but is preferably an organic peroxide in which a cross-linking reaction does not extremely proceed at a processing temperature in a rubber composition, and a decomposition temperature ( Half-life is 10
A dialkyl peroxide having a temperature of 80 ° C. or more is preferable. Specifically, dicumyl peroxide, di-t-butyl peroxide, 1,3-bis-
(T-butylperoxyisopropyl) benzene, 4,
4'-di- (t-butylperoxy) valeric acid n-
Butyl and 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane are exemplified. The content of the organic peroxide in the rubber composition is preferably set at 10
It is 1 to 10 parts by mass with respect to 0 parts by mass. If the amount is less than 1 part by mass, the crosslink density becomes low, and the modulus or the like may be impaired. If it exceeds 10 parts by mass, the crosslink density may be high and the elongation at break may be low.

The 2,4-dimercapto-6-substituted-1,3,5-substituted compound represented by the above formula 1 used in the rubber composition is used.
In the triazine, R in the formula is selected from the group consisting of a mercapto group, an alkoxy group, a monoalkylamino group, a dialkylamino group, a monocycloalkylamino group, a dicycloalkylamino group, and an N-alkyl-N-arylamino group. Is the base. Considering the bonding rate with the metal and the polymer having an epoxy group, 2,4,6-trimercapto-1,3, in which R is a mercapto group,
5-Triazine is preferred. Further, two or more 2,4-dimercapto-6-substituted-1,3,5-triazines represented by the above formula 1 having different Rs may be used in combination.

The content of the 2,4-dimercapto-6-substituted-1,3,5-triazine represented by the above formula 1 in the rubber composition is preferably 100 parts by mass of the raw rubber used in the rubber composition. 0.1 to 15 parts by mass per part. If the amount is less than 0.1 part by mass, the adhesion between the rubber composition and the metal may be insufficient. If the amount exceeds 15 parts by mass, crosslinking may be inhibited, and the modulus may decrease. If the amount exceeds 15 parts by mass, a large amount of reaction with the polymer having an epoxy group described above occurs. In some cases, the adhesion between the metal and the metal becomes insufficient.

JP-A-55-125155 discloses an organic peroxide-crosslinkable polymer, an organic peroxide,
Epoxy resin and 2,4-dimercapto-6-substituted-
Although there is a description of a polymer composition comprising 1,3,5-triazine, the composition is characterized in that chlorine in a chlorine-containing polymer such as chlorinated polyethylene and 2,4-dimercapto-
Reaction of 6-substituted-1,3,5-triazine, reaction of 2,4-dimercapto-6-substituted-1,3,5-triazine with epoxy resin, 2,4-dimercapto-6-substituted-
It utilizes a reaction between 1,3,5-triazine and copper in brass, and a non-chlorine-containing polymer does not cause an adhesive reaction, so that the adhesiveness was insufficient. Further, in the above publication, there is no mention of the adhesiveness of the non-chlorine-containing polymer, and chlorinated polyethylene rubber and chlorosulfonated polyethylene rubber are used in Examples. Furthermore, no mention is made of the crosslinkability of the epoxy resin by organic peroxide crosslinking, and an epoxy resin having no organic peroxide crosslinking property is used in the examples. That is,
Epoxy resins are 2,4-dimercapto-6-substituted-1,3,5 reacted with chlorine in the polymer and copper in the brass.
-It is presumed that it was added in expectation of the effect of adhesion to a metal by intercalating with and cross-linking with a triazine, and an adhesion reaction by the same reaction mechanism in a non-chlorine-containing polymer could not be expected. Are not co-crosslinked with non-chlorine-containing polymers, but due to a different mechanism of action.

On the other hand, the rubber composition is not an epoxy resin which is generally considered to greatly contribute to adhesion to metals, but has other organic peroxide crosslinkable epoxy groups. It has been found that the use of a polymer improves the adhesiveness. Although the reason for this has not been elucidated, general epoxy resins have poor radical reactivity and are unlikely to undergo hydrogen abstraction, and since there is no double bond other than the aromatic ring in the main chain, a cross-linking reaction other than epoxy groups occurs. On the other hand, the polymer having an epoxy group used in the rubber composition has a high radical reactivity of a methylene chain such as ethylene, or a cross-linking reaction such as a double bond other than an aromatic ring in the main chain. It can also have a contributing part, so that the bond with the raw rubber effectively occurs, and at the same time, 2,4-dimercapto-6-substituted-1,
3,5-Triazine binds to a metal via a mercapto group, and forms a bond with a polymer having an epoxy group by a ring-opening reaction of an epoxy group via another mercapto group in the same molecule. Conceivable. That is, the bond between the raw rubber and the polymer having an epoxy group, the bond between the polymer having an epoxy group and the 2,4-dimercapto-6-substituted-1,3,5-triazine represented by the above formula 1 and the bond represented by the above formula 1 2,4-dimercapto-6-substituted-
Since the 1,3,5-triazine and the metal are simultaneously bonded, the rubber composition and the metal are bonded and integrated.
In addition, some of the polymers having an epoxy group are bonded by reacting with a metal, and when a polymer having such an epoxy group is selected, a polymer having a stronger bond between the rubber composition and the metal is used. Becomes

In addition to the above-mentioned components, the rubber composition may further comprise a crosslinking aid, a reinforcing agent (such as carbon black) as necessary, as long as the adhesion to metal, the modulus, the set resistance and the heat resistance are not impaired. ), Additives such as fillers, anti-aging agents, processing aids, plasticizers, softeners, and the like.

It is preferable that triallyl isocyanurate and / or triallyl cyanurate be blended as a crosslinking aid because modulus and adhesion to metal are improved. Triallyl isocyanurate and triallyl cyanurate are trifunctional polymerizable monomers, and are used as a crosslinking aid of an organic peroxide-crosslinked rubber composition,
When used in the rubber composition, the crosslinking density can be increased and the modulus can be improved. Only one of triallyl isocyanurate and triallyl cyanurate may be used, or both may be used in combination. The content of triallyl isocyanurate and / or triallyl cyanurate in the rubber composition depends on the content of the epoxy group in the polymer having an epoxy group, but generally 100 parts by mass of the raw rubber used in the rubber composition. Is preferably 0.1 to 30 parts by mass.

Examples of the filler include silica (white carbon), calcium carbonate, barium sulfate, talc, clay and titanium oxide. Among them, silica is preferred. Silica is an acidic compounding agent and effectively contributes to the control of the reaction rate of 2,4-dimercapto-6-substituted-1,3,5-triazine represented by the above formula 1, and stabilizes physical properties and adhesiveness. . Although silica (white carbon) is not particularly limited, for example, dry white carbon, wet white carbon used as a filler for rubber,
Colloidal silica and precipitated silica described in JP-A-62-62838 are exemplified. Among them, wet-process white carbon mainly containing hydrous silicate is preferable. Hydrous silicate, which is a main component of wet process white carbon, has a nitrogen adsorption specific surface area (BET method) of 50 to 400 m ^2.
/ G, preferably 100 to 250 m ² / g of hydrous silicic acid. Further, hydrous silicic acid is p
H (hydrogen ion concentration) is preferably less than 7.0, and more preferably pH 6.7 or less. pH
Is within the above range, the early reaction of 2,4-dimercapto-6-substituted-1,3,5-triazine can be suppressed. Incidentally, the nitrogen adsorption specific surface area was determined according to ASTM D303.
7 This is a value measured by the BET method according to 81,
Is a value obtained by stirring silica in water, filtering the silica, and then measuring the pH of the filtrate using a pH meter. The content of silica in the rubber composition depends on, for example, the content of the epoxy group in the polymer having an epoxy group, but is generally preferably 1 to 50 parts by mass relative to 100 parts by mass of the raw rubber.

Although triallyl isocyanurate and / or triallyl cyanurate and silica are effective even if they are separately mixed, a mixture containing triallyl isocyanurate and / or triallyl cyanurate and silica is heat-treated. It is particularly preferable to mix the resulting mixture into a solidified product. The solidified product is preferably triallyl isocyanurate or the like, preferably 30 to 80% by mass,
More preferably, it is a solidified substance present on the silica surface of 50 to 70% by mass. Details of this solidification are unknown,
Triallyl isocyanurate and / or triallyl cyanurate, which are polymerizable monomers, are formed by performing a heat treatment on the surface of silica particles, with a portion of the surface of the silica particles being subjected to a polymerization reaction using a hydroxyl group or the like present on the silica particle surface as a catalyst. It is thought that it was done. The conditions for the heat treatment are as follows:
Any conditions may be used as long as the triallyl isocyanurate and / or the triallyl cyanurate and the silica are solidified, but preferably at least 150 ° C, more preferably at a temperature of 160 to 200 ° C, preferably at least 10 minutes, More preferably, heating is performed in air for about 30 minutes to 24 hours. When the heat treatment conditions are in this range, a solid can be obtained efficiently.

The anti-aging agent is not particularly limited as long as it is a heat-resistant anti-aging agent, a weather-resistant anti-aging agent and the like which are usually used in rubber compositions. Examples thereof include naphthylamines (phenyl-α-naphthylamine and the like). , Diphenylamines (such as octylated diphenylamine), p-phenylenediamines (N-isopropyl-N'-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl)-
N'-phenyl-p-phenylenediamine, N, N'-
Amine-based antioxidants such as di-2-naphthyl-p-phenylenediamine and the like; 2,2,4-trimethyl-1,2-
A quinoline antioxidant such as a polymer of dihydroquinoline;
Monophenols (2,6-di-t-butyl-4-methylphenol, styrenated phenol, etc.), bis, tris, polyphenols (tetrakis- [methylene-3-)
(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane and the like.

Examples of the softener include process oils such as paraffin, naphthene and aroma; plant oils such as castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, and rosin.

The plasticizer is, for example, diethyl phthalate,
Phthalates such as dibutyl phthalate, di- (2-ethylhexyl) phthalate and di-n-octyl phthalate; di- (2-ethylhexyl) adipate, di-
Synthetic plasticizers such as adipate esters such as (butoxyethoxyethyl) adipate; and trimellitate esters such as tri- (2-ethylhexyl) trimellitate.

The method of mixing a rubber composition according to the present invention is a method of obtaining the rubber composition by mixing the above-mentioned components, wherein the temperature of the rubber composition is maintained at 140 throughout the mixing process.
C. or lower, preferably 130.degree. C. or lower. Generally, the ring-opening reaction of the epoxy group is activated in the presence of a catalyst such as an acid or an amine, and is further promoted at a high temperature exceeding 140 ° C. The epoxy group of the polymer having an epoxy group, which is a component of the rubber composition, is also similar to a normal epoxy group, in the presence of a catalyst such as an acid or an amine, particularly at a high temperature exceeding 140 ° C., and ring-opening of the epoxy group. Reaction is likely to occur. Accordingly, by maintaining the temperature of the rubber composition at 140 ° C. or lower throughout the entire mixing process, the epoxy group of the polymer having an epoxy group during mixing and the 2,4-dimercapto-acid represented by the above formula 1, which is an acidic additive, are added. 6-substitution-
Even in the presence of 1,3,5-triazine, the reaction with the mercapto group of 2,4-dimercapto-6-substituted-1,3,5-triazine occurs, and the adhesion to the crosslinked metal becomes unstable. Can be prevented. Further, silica as an acidic compounding agent suppresses the activation of 2,4-dimercapto-6-substituted-1,3,5-triazine represented by the above formula 1, and the epoxy group and 2,4-dimercapto- It is considered that this has an effect of suppressing the progress of the reaction of the mercapto group of 6-substituted-1,3,5-triazine.

Further, in the method of mixing the rubber composition of the present invention, the 2,4-dimercapto-6 represented by the above formula (1) is used.
-It is preferable to maintain the temperature of the rubber composition in the step after the addition of the substituted-1,3,5-triazine at 100 ° C or lower. The 2,4-dimercapto-6-substituted-1,
When the temperature exceeds 100 ° C., 3,5-triazine becomes more effective as a ring-opening catalyst for epoxy groups.
By maintaining the temperature of the rubber composition at 100 ° C. or lower in the process after the addition of dimercapto-6-substituted-1,3,5-triazine, it is possible to prevent the adhesive strength to the metal after crosslinking from becoming unstable. In addition, it is possible to prevent physical properties such as modulus after crosslinking from being reduced.

In the method of mixing the rubber composition of the present invention, the temperature may be adjusted as described above, and the order and number of inputs of the essential and optional components of the rubber composition, the mixing time, the type of mixer used, and the like. Is not particularly limited. Further, the mixing step may be divided into a plurality of times.

The method of adjusting the temperature is not particularly limited. Since the rubber composition generates heat during mixing, in order to suppress the heat generation and adjust the temperature as described above, it is possible to reduce the charge amount or mix while cooling the mixer. Further, it is preferable that the mixing step is divided into two or more times, the rubber composition is discharged before reaching the upper limit temperature, and after cooling, the temperature is adjusted by a method of performing the next step. The number of steps of the divided mixing process is preferably 2 to 5 times, and more preferably 2 times because the operation is less complicated. Furthermore, the temperature may be adjusted by appropriately combining them.

The mixer to be used includes, for example, a closed mixer, an open-type kneading roll machine, and a continuous mixer. Examples of the closed mixer include a Banbury mixer, an intermix, and a kneader. Above all, a Banbury mixer is preferable.

Hereinafter, preferred examples of the method for mixing the rubber composition of the present invention will be described, but the present invention is not limited thereto. (1) 100 parts by mass of an organic peroxide crosslinkable raw material rubber is charged into a Banbury mixer and mixing is started. (2) After 0 second to 1 minute, 1 to 100 parts by mass of a polymer having an epoxy group capable of crosslinking with an organic peroxide is charged. (3) After 0 seconds to 2 minutes, an appropriate amount of various additives, which are optional components, and 2,4-dimercapto-
0.1 to 15 parts by mass of 6-substituted-1,3,5-triazine are introduced. (4) After 0 to 5 minutes, a crosslinking aid (triallyl isocyanurate and / or triallyl cyanurate and diallyl phthalate), which is an optional component, is further added. (5) After 2 to 10 minutes, the rubber composition is inverted by raising and lowering the ram of the Banbury mixer. (6) After 3 to 15 minutes, the temperature of the rubber composition is 130 to 14
When the temperature reaches about 0 ° C., the rubber composition is discharged, and Step 1 is completed. (7) After allowing the rubber composition obtained in Step 1 to cool, put it in a Banbury mixer together with 1 to 10 parts by mass of the organic peroxide and restart mixing. (8) After 5 seconds to 5 minutes, the temperature of the rubber composition is 80 to 100.
When the temperature reaches about ° C, the rubber composition is discharged, and Step 2 is completed to complete the mixing.

The following is another preferred example. In the following mixing method, the temperature of the rubber composition in the step after the addition of the 2,4-dimercapto-6-substituted-1,3,5-triazine represented by the above formula 1 is maintained at 100 ° C. or less. preferable. (1) 100 parts by mass of an organic peroxide crosslinkable raw material rubber is charged into a Banbury mixer and mixing is started. (2) After 0 second to 1 minute, 1 to 100 parts by mass of a polymer having an epoxy group capable of crosslinking with an organic peroxide is charged. (3) After 0 seconds to 2 minutes, appropriate amounts of various additives, which are optional components, are further added. (4) After 0 to 5 minutes, a crosslinking aid (triallyl isocyanurate and / or triallyl cyanurate and diallyl phthalate), which is an optional component, is further added. (5) After 2 to 10 minutes, the rubber composition is inverted by raising and lowering the ram of the Banbury mixer. (6) After 3 to 15 minutes, the temperature of the rubber composition is 130 to 14
When the temperature reaches about 0 ° C., the rubber composition is discharged, and Step 1 is completed. (7) After allowing the rubber composition obtained in Step 1 to cool, a Banbury mixer is used to prepare 0.1 to 15 of 2,4-dimercapto-6-substituted-1,3,5-triazine represented by the above formula 1.
The mixing is resumed by charging together with 1 part by mass and 1 to 10 parts by mass of the organic peroxide. (8) After 5 seconds to 5 minutes, the temperature of the rubber composition is 80 to 100.
When the temperature reaches about ° C, the rubber composition is discharged, and Step 2 is completed to complete the mixing.

The rubber composition obtained by the mixing method of the present invention stably exhibits adhesion to metal. Since the rubber composition obtained by the mixing method of the present invention has high modulus, high set resistance and high heat resistance,
For rubber and metal composites, hoses, belts, tires,
It can be used for a wide range of applications such as rolls and molds. In particular, since it has a high adhesiveness to copper or an alloy containing copper, it can be used very suitably for rubber products combined with steel plates or steel wires of brass plating or the like.

[0038]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. <Raw material of rubber composition> (1) Raw rubber Hydrogenated acrylonitrile-butadiene copolymer rubber (HN
BR) Composition: Unit portion from unsaturated nitrile (Y portion; VC)
N) 33.0% by mass, unit portion from conjugated diene (Z portion; C = C) 1.3% by mass, unit portion from ethylenically unsaturated monomer other than unsaturated nitrile and unit from conjugated diene A hydrogenated unit (X; CC)
65.7% by mass

(2) Compounding agent I (polymer having epoxy group) EMA-g-GMA (ethylene-methyl acrylate copolymer rubber obtained by graft polymerization of glycidyl methacrylate):
Bond First 7L, manufactured by Sumitomo Chemical Co., Ltd.

(3) Compounding agent II SRF grade carbon black: Asahi # 50, zinc oxide (ZnO) stearic acid manufactured by Asahi Carbon Co., Ltd. Antioxidant: Nocrack MBZ, Ouchi Shinko Chemical Co., Ltd. wax (WAX): Sunwax 171P , Manufactured by Sanyo Chemical

(4) Compounding agent III 2,4,6-trimercapto-1,3,5-triazine: ZISNET-F, manufactured by Sankyo Chemical Co., Ltd.

(5) Combination agent IV triallyl isocyanurate (TAIC) diallyl phthalate (DAP)

(6) Crosslinking agent (organic peroxide) 1,3-bis (t-butylperoxyisopropyl) benzene: Percadox 14/40 (40% by mass)
Chemicals manufactured by Akzo

<Preparation of Rubber Composition> Each rubber composition was obtained from the above raw materials at the mass ratios shown in Table 1 using a Banbury mixer by the following mixing method (Table 2). (Example 1) (1) Raw rubber and compounding agent I were added to a Banbury mixer.
(Polymer having epoxy group) was charged and mixing was started. (2) After one minute, the ingredients II and III were further charged. (3) When the temperature of the rubber composition reached about 110 ° C. (about 3 minutes), the compounding agent IV was further added. (4) After 3 minutes, the rubber composition was inverted by raising and lowering the ram of the Banbury mixer. (5) When the temperature of the rubber composition reached about 130 ° C. (about 4 minutes), the rubber composition was discharged, and Step 1 was completed. (6) After allowing the rubber composition obtained in Step 1 to cool, the mixture was added to a Banbury mixer together with a crosslinking agent (organic peroxide) to restart mixing. (7) When the temperature of the rubber composition reached about 100 ° C. (about 1 minute), the rubber composition was discharged, and Step 2 was completed to complete the mixing.

(Example 2) (1) Raw rubber and compounding agent I were added to a Banbury mixer.
(Polymer having epoxy group) was charged and mixing was started. (2) One minute later, the compounding agent II was further charged. (3) When the temperature of the rubber composition reached about 110 ° C. (about 3 minutes), the compounding agent IV was further added. (4) After 3 minutes, the rubber composition was inverted by raising and lowering the ram of the Banbury mixer. (5) When the temperature of the rubber composition reached about 130 ° C. (about 4 minutes), the rubber composition was discharged, and Step 1 was completed. (6) After allowing the rubber composition obtained in Step 1 to cool, the mixture was added to the Banbury mixer together with the compounding agent III and the crosslinking agent (organic peroxide) to restart mixing. (7) When the temperature of the rubber composition reached about 100 ° C. (about 1 minute), the rubber composition was discharged, and Step 2 was completed to complete the mixing.

Comparative Example 1 (1) Raw rubber and compounding agent I were added to a Banbury mixer.
(Polymer having epoxy group) was charged and mixing was started. (2) After one minute, the ingredients II and III were further charged. (3) When the temperature of the rubber composition reached about 130 ° C. (about 4 minutes), the compounding agent IV was further added. (4) After 4 minutes, the rubber composition was inverted by raising and lowering the ram of the Banbury mixer. (5) When the temperature of the rubber composition reached about 160 ° C. (about 5 minutes), the rubber composition was discharged, and Step 1 was completed. (6) After allowing the rubber composition obtained in Step 1 to cool, the mixture was added to a Banbury mixer together with a crosslinking agent (organic peroxide) to restart mixing. (7) When the temperature of the rubber composition reached about 100 ° C. (about 1 minute), the rubber composition was discharged, and Step 2 was completed to complete the mixing.

[0047]

[Table 1]

[0048]

[Table 2]

The following tests were performed on each rubber composition obtained by each of the above mixing methods. <Adhesion Test> The adhesion test was carried out in accordance with the provisions of JIS K6256 “90 ° Peeling Test of Metal Piece and Vulcanized Rubber”. Each of the obtained rubber compositions is formed into a sheet having a thickness of 2.5 mm by a laboratory roll, and combined with a brass plate,
Crimped. However, a cellophane paper was disposed in a portion to be gripped by the chuck during peeling, so that the upper and lower layers did not adhere. Then, it was vulcanized under pressure at a surface pressure of 3.0 MPa at 160 ° C. for 60 minutes using a laboratory press molding machine and integrated to obtain a test piece that was a composite of brass and rubber. After the test piece was left at room temperature for 24 hours, the test piece was cut into a width of 2.54 cm, and a peeling test for peeling the rubber composition from the brass plate was performed. The peel strength is measured according to JIS K6256.
The test was performed at a tensile speed of 50 mm / min using a tensile tester specified in JIS K6256 in accordance with the provisions of “90-degree peel test of metal piece and vulcanized rubber”. When the value of the peel strength was 150 N / 25 mm or more, it was determined that the adhesiveness was good.

<Tensile Stress (Modulus) Test> Each of the obtained rubber compositions was vulcanized under pressure at 160 ° C. for 60 minutes to form a sheet having a thickness of 2 mm. In accordance with the provisions of JIS K6251, a dumbbell-shaped No. 3 test piece was punched out of this sheet, and the test piece was cut out in accordance with the provisions of JIS K6251.
The% modulus (M ₁₀₀ ) was measured. When the value of the 100% modulus (M ₁₀₀ ) was 9.0 MPa or more, it was regarded as good.

The results are shown in Table 3. The rubber composition obtained by the method of mixing the rubber composition of the present invention (Examples 1 and 2) has a rubber composition temperature of 14 throughout the mixing process.
Since the mixture was maintained at 0 ° C. or less, it was found that the mixture exhibited high adhesion to metal. In particular, the temperature of the rubber composition in the step after the addition of the 2,4-dimercapto-6-substituted-1,3,5-triazine represented by the above formula 1 is set to 10
It can be seen that when the rubber composition was mixed while being kept at 0 ° C. or lower (Example 2), the obtained rubber composition was also excellent in modulus. On the other hand, when the temperature of the rubber composition exceeds 140 ° C. in all the mixing steps (Comparative Example 1), the adhesiveness to metal becomes unstable.

[0052]

[Table 3]

[0053]

According to the method of mixing a rubber composition of the present invention, the rubber composition exhibits a stable adhesiveness to metal. Since the rubber composition obtained by the mixing method of the present invention has high modulus, high set resistance and high heat resistance,
For rubber and metal composites, hoses, belts, tires,
It can be used for a wide range of applications such as rolls and molds. In particular, since it has high adhesiveness to copper or an alloy containing copper, it can be very suitably used for rubber products and the like combined with brass-plated steel plates and steel wires.

 ──────────────────────────────────────────────────の Continued on the front page F-term (reference) 4F070 AA05 AA06 AA07 AA08 AA09 AA13 AA15 AA16 AA18 AA23 AA32 AA34 AA40 AB08 AB16 AC15 AC16 AC23 AC27 AC45 AC50 AC56 AC66 AC87 AE01 AE02 AE03 AE08 FB06 AC1 AC03 AC03 AC04 AC081 AC091 AC111 AC121 BB071 BB151 BB231 BB241 BB271 BD121 BD141 BG041 CD012 CP031 CQ011 EK036 EU187 EV347 FD010 FD020 FD030 FD146 FD150 GM01 GN01

Claims (2)

[Claims] 1. An organic peroxide-crosslinkable raw material rubber (100 parts by mass), an organic peroxide-crosslinkable epoxy group-containing polymer (1-100 parts by mass), an organic peroxide (1-10 parts by mass) and A method for mixing a rubber composition containing 0.1 to 15 parts by mass of the indicated 2,4-dimercapto-6-substituted-1,3,5-triazine, wherein the temperature of the rubber composition is kept at 140 throughout the mixing process. A method for mixing a rubber composition which is maintained at a temperature of not more than ℃. Embedded image Wherein R is a group selected from the group consisting of a mercapto group, an alkoxy group, a monoalkylamino group, a dialkylamino group, a monocycloalkylamino group, a dicycloalkylamino group, and an N-alkyl-N-arylamino group. Represents.) (2) The 2,4-dimercapto-6-substituted-
The method for mixing a rubber composition according to claim 1, wherein the temperature of the rubber composition in a step after the addition of 1,3,5-triazine is maintained at 100C or lower.