JPH03153706A - Hydrogenated nitrile rubber composition and its production - Google Patents

Abstract

PURPOSE:To obtain a hydrogenated nitrile rubber of markedly improved processability and improved storage stability by selectively hydrogenating the C-C double bonds in a nitrile rubber molecule in the presence of a thiuram compound or a benzothiazole compound. CONSTITUTION:A process for obtaining a hydrogenated nitrile rubber by selectively hydrogenating the C-C double bonds in a nitrile rubber molecule, wherein 0.01-5 pts.wt., per 100 pts.wt. rubber component, at least one of compounds of formulas I and II is added, In the formulas, (x) is 1-6, X is formula III (wherein R and R' are each phenyl or 1-6C alkyl) or formula IV, and R''' is H, formula V, formula VI or the like. Examples of the compounds of formula I include tetramethylthiuram monosulfide and tetramethylthiuram disulfide. Examples of the compounds of formula II include 2-mercaptobenzothiazole and dibenzothiazyl disulfide.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a hydrogenated nitrile rubber composition with improved processability and storage stability, and a method for producing the same. The hydrogenated nitrile rubber of the present invention can be used for automobile rubber parts,
It is also used as a raw material for other industrial rubber parts.

(Prior art) Hydrogenated nitrile rubber, which is obtained by selectively hydrogenating the carbon-carbon double bonds in the molecules of nitrile rubber, which is an oil-resistant rubber, maintains the oil resistance of conventional nitrile rubber and has high heat resistance. Due to its improved weather resistance, its use has been expanding in recent years as a rubber member for automobile parts and the like, which require physical properties such as oil resistance, heat resistance, and weather resistance.

(Problem to be Solved by the Invention) However, when nitrile rubber is hydrogenated, the Mooney viscosity of the rubber increases due to the reduction of carbon-carbon double bonds in the molecule, which causes problems in the rolls used when kneading the rubber. There is a noticeable tendency for processability such as wrapability to deteriorate. This point is a major drawback of hydrogenated nitrile rubber, and is an obstacle when manufacturing rubber parts, and improvements are desired.

One way to improve the processability of rubber is to add chemicals such as plasticizers and processing aids, but if you change the rubber formulation using this method, the desired rubber product will not be produced. This is not preferable because the physical properties change. Therefore,
It is desired to improve the processability of the rubber itself without changing the formulation or physical properties of the rubber.

Additionally, the metal catalysts used when hydrogenating nitrile rubber often have the property of promoting rubber deterioration, and if large amounts of these metal catalysts remain in the rubber, the storage stability of the rubber deteriorates. There is.

For this reason, it has become common practice to remove used metal catalysts during the manufacturing process of hydrogenated nitrile rubber. However, it is impossible to completely remove the catalyst industrially, and it is desired to develop a hydrogenated nitrile rubber that has excellent storage stability even if a small amount of the catalyst remains in the rubber.

(Means for Solving the Problems) As a result of intensive studies to improve the processability of hydrogenated nitrile rubber, the inventors of the present invention have developed the following method in the process of hydrogenating nitrile rubber to obtain hydrogenated nitrile rubber. Surprisingly, by adding at least one of the compounds represented by the general formula ([) or (n), processability can be improved without changing physical properties such as tensile properties and compression set of hydrogenated nitrile rubber. It has been discovered that this can be significantly improved and the storage stability of the rubber can also be improved, leading to the present invention.

The compound represented by the following general formula (1) or (II) is a chemical that is widely used as a rubber vulcanization accelerator in -fG, and when blended with rubber or when the blended amount is varied, it improves the vulcanization of rubber. It was common knowledge in the rubber industry to think that it changes the sex. However, in the present invention, even when this compound was added, the desired objective was successfully achieved without changing the vulcanizability of the hydrogenated nitrile rubber. This holds true for both sulfur vulcanization systems and peroxide vulcanization systems.

That is, an object of the present invention is to provide a hydrogenated nitrile rubber composition with improved processability and storage stability, and a method for producing the same. In the process of selectively hydrogenating carbon double bonds to obtain hydrogenated nitrile rubber, the following general formula (N or ([
A method for producing hydrogenated nitrile rubber, characterized in that 0.01 to 5 parts by weight of at least one of the compounds represented by r) is added to 100 parts by weight of the rubber component,
, R' represents a phenyl group or Al having 1 to 6 carbon atoms] [However, -R'' is -H1CH.

CH.

and a hydrogenated nitrile rubber composition produced thereby.

Hereinafter, the hydrogenated nitrile rubber composition of the present invention and the method for producing the same will be described in detail.

The raw material nitrile rubber used in the present invention contains a conjugated diene and α,
They are copolymers of β-unsaturated nitrile compounds and, if necessary, other monomers that can be copolymerized with them.

Conjugated dienes include butadiene, isoprene, 1.3-
Examples include pentagene, but butadiene is preferred.

Examples of the α,β-unsaturated nitrile compound include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, and the like, with acrylonitrile being preferred.

Other monomers that can be copolymerized with them include α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid, or methyl esters of these α,β-unsaturated carboxylic acids; ethyl ester, n
-esters such as butyl esters and isodecyl esters,
Non-conjugated divinyl compounds such as divinylbenzene, divinylxylene and divinyl ether; polyhydric (meth)acrylate compounds such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate;
-anilinophenyl)maleimide, N-(4-(4
-methylanilinophenyl]maleimide, anilinostyrene, l-anilinophenyl-2-methyl-1,
3-butadiene, 2-anilinophenyl-1,3-butadiene, 2-anilinophenyl-3-methyl-1,3-butadiene, 3-((4-anilino)phenylimino)-2
Methylpropene, 4-anilino-N-(4-vinylbenzyl)aniline, 4-anilinophenyl-4-vinylbenzyl ether, N-(4-anilinophenyl)vinylsulfonamide, N-(4-anilinophenyl) )-4-
Vinylbenzenesulfonamide, N-(4-anilinophenyl)acrylamide, N-(4-anilinophenyl)methacrylamide, N-(4-anilinophenyl)cinnamamide, N-(4-anilinophenyl)crotonamide , N-(4-(4-methylanilino)phenyl)
Methacrylamide, 3-N-(4-anilinophenyl)
Amino-2-hydroxypropyl (meth)allyl ether, 1O-N-(4-anilinophenyl)amino-9-
Hydroxy-10-〇-octyldecyl (meth)acrylate, 5-N-(4-anilinophenyl)amino-2
-Hydroxypentyl (meth)acrylate, 2-N-
Examples include vinyl deterioration inhibitor monomers having an anilinophenyl skeleton in the molecule, such as (4-anilinophenyl)aminoethyl (meth)acrylate. Other monomers that can be copolymerized with these conjugated dienes and the α,β-unsaturated nitrile compound may be used alone or in combination, if necessary.

The ratio of the conjugated diene, the α,β-unsaturated nitrile compound, and other monomers that can be copolymerized with them in the raw nitrile rubber used in the present invention is not particularly limited; From the viewpoint of the desired physical property balance of the hydrogenated nitrile rubber, it is preferable that the amount of the α,β-unsaturated nitrile compound is 20 to 55% by weight and the other monomer copolymerizable with them is 0 to IO% by weight.

There are no particular restrictions on the method of polymerizing the raw material nitrile rubber used in the present invention, and a typical emulsion polymerization method can be employed.

The production of hydrogenated nitrile rubber in the present invention must include a step of adding the compound represented by the general formula (1) or (II) to the step of hydrogenating the raw nitrile rubber.

In the step of hydrogenating the raw nitrile rubber, a method may be adopted in which carbon-carbon double bonds in the nitrile rubber molecules are selectively hydrogenated. For example, the latex of the raw nitrile rubber or the raw nitrile rubber is dissolved in an organic solvent. A hydrogenation catalyst is added to the solution and brought into contact with atomic or gaseous hydrogen under heating in a reaction vessel. There is no particular limit to the degree of hydrogenation (hydrogenation rate) of the carbon-carbon double bonds in the nitrile rubber molecules, but from the viewpoint of the physical properties of the desired hydrogenated nitrile rubber, the carbon-carbon double bonds of the raw material nitrile rubber Preferably, 70% or more of the bonds are hydrogenated. As a catalyst, Pt, Pd, Rh
, Ru, etc. can be supported on porous carbon or the like, or used in the form of a metal complex. After the hydrogenation reaction is completed,
By removing the solvent by an appropriate method and drying, a solid hydrogenated nitrile rubber can be obtained.

The step of adding the compound represented by the general formula (1) or (II) is 1. It may be carried out before, after or during the hydrogenation reaction of the raw material nitrile rubber, but in order to carry out the hydrogenation reaction smoothly, it is preferably carried out after the hydrogenation reaction.

There is no particular restriction on the method of adding the compound represented by the general formula (1) or (II), as long as the compound is added uniformly and effectively to the hydrogenated nitrile rubber. For example, this compound can be dissolved in an organic solvent and added to the nitrile rubber solution after the hydrogenation reaction, or after recovering the hydrogenated nitrile rubber from the nitrile rubber solution after the hydrogenation reaction, it can be directly used using a roll or extruder. Just add it.

The amount of at least one compound represented by the above general formula (1) or (II) to be added is 0.01 to 5 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the rubber component.
Parts by weight. If the amount added is too small, the effect of improving processability and storage stability will be reduced, and if it is too large, the physical properties of the hydrogenated nitrile rubber will be unbalanced, which is not preferable.

Examples of the compound represented by the general formula (1) are:
Tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram monosulfide, tetrabutylthiuram disulfide, N-N'-dimethyl-N-N' diphenylthiuram disulfide, dipentamethylene Examples include thiuram monosulfide, dipentamethylenethiuram, disulfide, dipentamethylenethiuram tetrasulfide, dipentamethylenethiuram hexasulfide, and the like.

Examples of the compound represented by the general formula (n) are:
2-mercaptobenzothiazole, dibenzothiazyl disulfide, N-cyclohexylbenzothiazyl-2-
Examples include sulfenamide, N-oxydiethylenebenzothiazyl-2-sulfenamide, N-tertbutylbenzothiazyl-2-sulfenamide, and the like.

Hereinafter, the present invention will be explained in detail with reference to examples, but the present invention is not limited to the following examples unless the gist thereof is exceeded.

[Examples 1 to 12 and Comparative Examples 1 to 4] Raw material nitrile rubbers having the grades shown in [Table 1] were prepared by an emulsion polymerization method.

These raw nitrile rubbers were dissolved in acetone, [Table-
Hydrogenation was carried out under the conditions shown in 2]. A compound represented by general formula (1) or (II) dissolved in a small amount of acetone is added to the hydrogenated solution, and then water is added to precipitate hydrogenated nitrile rubber. After drying, Mooney viscosity was measured according to JIS K6384. The results are shown in [Table 3]. Note that the hydrogenation rate was calculated by the iodine value method.

Mooney viscosity is generally used as an index of rubber processability, and as can be seen from [Table 3], the examples according to the present invention have lower Mooney viscosity and superior processability than comparative examples.

Next, to examine storage stability, an accelerated test was conducted in which these rubbers were placed in a gear oven and heated at 70°C for 3 and 6 days. Storage stability can be judged by the change in Mooney viscosity, and as shown in [Table 3], the examples according to the present invention have better stability than the comparative examples even when heated at 70°C for 3 to 6 days. Excellent storage stability with little change in Mooney viscosity.

[Examples 13 to 14 and Comparative Examples 5 to 61 Hydrogenated nitrile rubber prepared according to the present invention and hydrogenated nitrile rubber prepared under exactly the same conditions except for adding tetramethylthiuram disulfide are shown in [Table 4]. [Table 5] shows the results of examining the rubber physical properties of samples that were kneaded and vulcanized using the method shown below in [Table 4] using the compounding recipe shown.

From [Table 5], the examples according to the present invention have lower Mooney viscosity than the comparative examples, and are actually excellent in Banbury mixer processability and roll processability.

From the Mooney scorch value, it can be seen that the vulcanizability does not change in both the sulfur vulcanization system and the peroxide vulcanization system.

In addition, the physical properties of the rubber such as tensile properties, hardness, and compression set are the same as those of the comparative example for both the sulfur-cured and peroxide-cured rubbers.

(Kneading method) Hydrogenated nitrile rubber, carbon black, stearic acid, and zinc oxide were placed in a Banbury-type closed mixer heated to 70°C and kneaded for 3 minutes. When the rubber mixture is discharged from the Banbury-type closed mixer, the state of the mixture is visually judged as "Banbury mixer workability" (judgment criteria; ○: the mixture is aggregated into lumps, but there is a slight amount of powder). Mixed, Δ: Divided into small lumps with many powdery substances) The rubber mixture discharged from the Banbury type closed mixer was mixed with 70
It was wound around two rolls heated to ℃ and sheeted for 1 minute. The wrapping state of the rubber at that time was judged visually and was defined as r-roll processability J.

(Judgment criteria; ◎: Closely adheres to the roll and does not buggy at all.
Δ: Difficult to baggy and wrap around a roll) Furthermore, the rubber mixture prepared in this way was coated on the vulcanized side (
Sulfur, C3, TT or "Perc Mill D40") were mixed in a Banbury-type closed mixer and formed into a sheet with two rolls to form an unvulcanized rubber compound.

(Vulcanization method) 160 in the case of sulfur vulcanization of unvulcanized rubber compound
'C130 minute press vulcanization, 160 for peroxide vulcanization
A test vulcanizate was prepared by vulcanization at 150'C for 150 minutes and then secondary vulcanization at 150'C for 2 hours.

(Effects of the Invention) The hydrogenated nitrile rubber produced according to the present invention is extremely stable during storage before producing rubber parts, and
It is suitable for use in automobile parts and industrial rubber parts because it is easy to process when manufacturing rubber parts and does not change the vulcanizability of the compound or the physical properties of the rubber parts.

Claims (2)

[Claims] (1) In the step of selectively hydrogenating carbon-carbon double bonds in the molecules of nitrile rubber to obtain hydrogenated nitrile rubber, at least one of the compounds represented by the following general formula (I) or (II) is used. A method for producing hydrogenated nitrile rubber, characterized in that 0.01 to 5 parts by weight of is added to 100 parts by weight of the rubber component. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) [However, x is an integer from 1 to 6, -X is ▲Mathematical formulas, chemical formulas,
There are tables, etc. ▼ (R, R' are phenyl groups or 1 carbon number
~6 alkyl group) or ▲There are mathematical formulas, chemical formulas, tables, etc.▼. ] ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(II) [However, -R''' is -H, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, Indicates ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼.] (2) A hydrogenated nitrile rubber composition produced by the production method according to claim 1.