JPH11302453A - Composition for vibration insulating rubber and vibration insulating rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition for the preparation of a vibration insulating rubber exhibiting durability as well as vibrationproofing properties well-balanced with soundproofing properties. SOLUTION: This vibration insulating rubber composition comprises (1) a rubber component comprising (a) 5-95 wt.%, of an aromatic vinyl monomer- butadiene copolymer rubber which bears an amino and/or a substituted amino group and has an average bound aromatic vinyl monomer content (such as styrene or the like) of 10-40 wt.% and a 1,2-linkage content in the whole butadiene units of 50 wt.% or more, the bound aromatic vinyl monomer content increasing or decreasing along the polymer chain from one end to the other, and (b) 95-5 wt.% of a diene rubber component other than the component (a) such as a polybutadiene rubber and the like and (2) a plasticizer such as DOP (dioctyl phthalate) having a freezing point or a pour point of -50 deg.C or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration rubber composition which can be used for engine mounts for automobiles and the like, and more particularly, it is used for producing an anti-vibration rubber having a balance between anti-vibration and sound-proof characteristics. Rubber composition.

[0002]

2. Description of the Related Art Anti-vibration rubber used for automobile engine mounts and the like is required to have anti-vibration and sound-proof properties. or,
The required anti-vibration characteristics are different depending on the portion where the anti-vibration rubber is mounted, and are various. Vibration isolation means that the frequency of shakes caused by engine vibrations is 5 to 30 Hz
The soundproofing property is a performance that reduces engine noise, muffled sound having a frequency of about 100 to 200 Hz generated by contact between a tire and a road surface, or unevenness of a road, and the like. However, in general, the vibration-proof property and the sound-proof property are opposite properties. For example, regarding the sound-proof property, natural rubber (NR) or NR / polybutadiene rubber (BR) is used.
Is excellent, but the anti-vibration, strength and heat resistance are insufficient. On the other hand, the styrene-butadiene copolymer rubber (SBR) / NR blend is excellent in anti-vibration and heat resistance. However, it is inferior in soundproofing, and it is difficult to obtain a vibration-proof rubber that satisfies the above two performances only with the rubber component.

[0003] For the above reasons, in recent years, a liquid seal mount has been used as an engine mount. The liquid ring mount is provided with a hollow chamber divided by a membrane in a rubber block, and a liquid such as ethylene glycol is sealed in the hollow chamber. In the liquid ring mount, a rubber block is formed by a rubber material having a function of damping vibration by a liquid moving between hollow chambers through a communication passage (orifice) provided in a membrane and a rubber material having characteristics similar to a spring. Function to enhance soundproofing. However, the liquid ring mount has a complicated structure, requires many man-hours for manufacturing, and is costly. Therefore, a vibration-proof rubber made of a rubber composition having a vibration-proof property and a sound-proof property is required.

In order to meet such a demand, a method of using a synthetic rubber having a molecule modified as a rubber component (Japanese Patent Publication No.
JP-A-62808), a method using a rubber composition to which an agent for reacting carbon with a rubber component is added (Japanese Patent Publication No. 2-522438), the amount of bound styrene is increased from one end to the other end along the polymer molecular chain. A method using a tapered styrene-butadiene copolymer rubber which increases or decreases toward the end (Japanese Patent Publication No. 7-88439) has been proposed. However, these methods cannot provide vibration-proof rubber and sound-proofing at a satisfactory level to the vibration-proof rubber, and require further improvement in soundproofing.

[0005] In order to enhance the soundproofing properties, usually, the amount of a rubber component is increased by reducing the amount of a filler such as carbon black, and the amount of a softening agent (process oil) is reduced.
Measures such as increasing the proportion of polybutadiene rubber in the raw rubber component have been taken. However, when the amount of carbon black or the like is reduced, it becomes difficult to impart the required hardness to the vibration-proof rubber, and when the amount of the softening agent is reduced, the workability is hindered, and in the use of polybutadiene rubber, When the ratio increases, problems such as insufficient dynamic fatigue resistance and heat resistance occur. Also, Japanese Patent Application Laid-Open No. 8-736
No. 58 and JP-A-8-269237 propose the use of a polybutadiene rubber having a modified terminal and a natural rubber, but satisfactory dynamic fatigue resistance cannot be obtained.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to manufacture a vibration-proof rubber having durability and a balance between vibration-proof and sound-proof. It is to provide a rubber composition which enables the following. The present inventors have conducted intensive studies to achieve the above object, and as a result, have an amino group, and the amount of bound aromatic vinyl monomer increases or decreases from one end to the other along the polymer molecular chain. The present invention finds that the object can be achieved by using a rubber composition containing a tapered aromatic vinyl monomer-butadiene copolymer rubber and a diene rubber other than this as a rubber component and a specific plasticizer. Was completed.

[0007]

Thus, according to the present invention, there is provided (1) (a) a copolymer rubber of an aromatic vinyl monomer and butadiene having an amino group and / or a substituted amino group. The average amount of the bonded aromatic vinyl monomer is 10 to 40% by weight, the content of 1,2 bonds in all butadiene units is 50% by weight or more, and the amount of the bonded aromatic vinyl monomer is A copolymer rubber of butadiene and an aromatic vinyl monomer increasing or decreasing from one end to the other along
95% by weight and (b) a rubber component composed of 95 to 5% by weight of a diene rubber other than the above, and (2) a solidification point or a pour point is-
A composition for a vibration-proof rubber characterized by containing a plasticizer at 50 ° C. or lower and a vibration-proof rubber obtained by molding and vulcanizing the composition are provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to embodiments. The copolymer rubber of the component (a) used in the present invention is a copolymer rubber of an aromatic vinyl monomer and a butadiene having an amino group and / or a substituted amino group, and has an average binding aromatic vinyl monomer Body weight is 10
40% by weight, the amount of bound aromatic vinyl monomer increases or decreases from one end to the other along the polymer molecular chain, and the content of 1,2 bonds in all butadiene units is 50% by weight or more. Is a copolymer rubber.

The aromatic vinyl monomer used for polymerizing the copolymer rubber of the component (a) is a vinyl monomer having an aromatic ring structure and a vinyl monomer having a benzene ring or a pyridine ring. Styrene, α-methylstyrene, 2-methylstyrene, 3-methyl-styrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t
Amino group-free aromatic vinyl monomers such as -butylstyrene, 5-t-butyl-2-methylstyrene, monochlorostyrene, dichlorostyrene and monofluorostyrene;
Aminostyrene, 2-N, N-dimethylaminostyrene, 4-N, N-dimethylaminostyrene, 2-N, N
-Bis (trimethylsilyl) aminostyrene, 2-vinyl (N, N-diisopropylbenzamide), 4-vinyl (N, N-diisopropylbenzamide), N, N-
Examples thereof include amino group-containing aromatic vinyl monomers such as dimethylaminoethylstyrene, N, N-diethylaminoethylstyrene, 2-vinylpyridine, and 4-vinylpyridine. Among these, an aromatic vinyl monomer containing no amino group is preferable, and styrene is particularly preferable.

The copolymer rubber of the component (a) is obtained by converting an aromatic vinyl monomer and butadiene using an organic alkali metal or organic alkaline earth metal catalyst and using a vinylating agent such as an ether or a tertiary amine. It can be obtained by conventionally known anionic polymerization using a Lewis base. For example, in the polymerization system before the start of polymerization, only butadiene is put as a monomer, and the amount of the aromatic vinyl monomer in the unreacted monomer in the polymerization reaction solution is gradually increased from the start of the polymerization. Alternatively, an aromatic vinyl monomer is added until the end of the polymerization so as to increase continuously. The polymerization temperature is preferably from -80 to + 120 ° C, more preferably from 0 to 110 ° C, particularly preferably from 20 to 100 ° C. The copolymer rubber (a) of the present invention may contain a monomer copolymerizable with an aromatic vinyl monomer and butadiene as long as the effects of the present invention are not impaired. it can.

As the polymerization solvent, any of the solvents conventionally used for the above-mentioned anionic polymerization of an aromatic vinyl monomer and butadiene can be used, which inhibits the polymerization reaction,
The solvent is not particularly limited as long as the solvent does not dissolve the monomer or the produced polymer. For example, n-pentane, n-hexane, cyclohexane, toluene, n-heptane and the like can be mentioned. These may be used in combination of two or more.

As the organic alkali metal, for example, n-
Organic lithium compounds such as butyllithium, sec-butyllithium, t-butyllithium, and phenyllithium;
Organic sodium compounds such as sodium naphthalene; and organic potassium compounds such as potassium naphthalene. Examples of the organic alkaline earth metal include organic magnesium compounds such as n-butyl magnesium and n-hexyl magnesium; organic calcium compounds such as ethoxy calcium and calcium stearate; and organic barium compounds such as ethoxy barium. These are 2
More than one species may be used in combination. Of these, organolithium compounds are preferred.

Unless the polymerization reaction is terminated by adding a polymerization terminator such as an alcohol such as methanol or ethanol or water to the obtained copolymer rubber, the above-mentioned active metal is added to the terminal of the polymer chain. A living polymer that is bound. One of the methods for introducing an amino group and / or a substituted amino group into a copolymer rubber is to introduce an amino group-containing aromatic vinyl monomer as a part of the aromatic vinyl monomer by copolymerization. And a method of copolymerizing a monomer other than an aromatic vinyl monomer having no amino group, butadiene and an aromatic vinyl monomer having an amino group and / or a substituted amino group copolymerizable therewith. This method is introduced by polymerization.

As another method, a living copolymer rubber is combined with (A) a compound having a bond represented by the following general formula (1) in a molecular chain, and (B) an amino group and / or a substituted amino group. End-modification method of reacting at least one compound selected from benzophenones and thiophenones, and a method of adding an alkali metal and / or an alkaline earth metal to a copolymer rubber after termination of polymerization and reacting with the above compound And the like. Among these copolymer rubbers, those obtained by using styrene as an aromatic vinyl monomer and modifying the terminal thereof are preferable. (Where X is an oxygen atom or a sulfur atom.) The details of the modification reaction will be described later.

The composition for vibration-proof rubber of the present invention comprises (1) a rubber component comprising a copolymer rubber of component (a) and a diene rubber other than component (b) (a), and (2) a plasticizer. Is blended. In the copolymer rubber of the component (a), the average amount of the bonded aromatic vinyl monomer is 10 to 40% by weight, preferably 15 to 30% by weight. When the average amount of the bonded aromatic vinyl monomer is too large, the loss factor at room temperature is large, but even if other diene rubbers of component (b) are blended, the dynamic magnification does not decrease, and the low-temperature vibration damping property is obtained. May be insufficient. On the other hand, when the average amount of the bonded aromatic vinyl monomer is too small, the loss coefficient at room temperature is small, and it is difficult to obtain a sufficient vibration damping effect. The copolymer rubber of the component (a) has a 1,2 bond content in all butadiene units of 50% by weight or more, preferably 60% by weight or more. 1,
If the content of the two bonds is too small, the compatibility with the diene rubber of the component (b) may be deteriorated, and the durability and the low-temperature vibration-proof property are improved while maintaining the excellent vibration-proof effect at room temperature. It becomes difficult.

In the copolymer rubber of the component (a), the amount of the bound aromatic vinyl monomer increases or decreases from one end to the other along the polymer molecular chain. The tendency to increase or decrease may be reversed in a very short molecular chain portion, but the tendency to increase or decrease from one end to the other is uniform and does not reverse as a whole.

The distribution (the degree of taper) of the amount of the bound aromatic vinyl monomer is such that 10% by weight of the total molecular chain length is measured from one end of the polymer chain.
In the portion, the amount of the bonded aromatic vinyl monomer is preferably １ ／ or less of the average amount of the bonded aromatic vinyl monomer,
More preferably, it is 1/5 or less, and in the portion of 10% by weight of the molecular chain length from the other end of the polymer chain, the amount of the bonded aromatic vinyl monomer is 1% of the average amount of the bonded aromatic vinyl monomer. It is preferably at least 0.5 times, more preferably at least 2 times. If the amount of the bound aromatic vinyl monomer at the end is too small or too large, the compatibility with the diene rubber of the component (b) may be deteriorated, and the durability and the low-temperature vibration-proof properties are improved. It becomes difficult.

The diene rubber of the component (b) used in the present invention is not particularly limited as long as it is a diene rubber other than the component (a). For example, natural rubber, polyisoprene rubber (high cis-1,4 bond content and low cis-1,4 bond content), polybutadiene rubber (high cis-1,4 bond content and low cis-1,4 bond content) SBR (emulsion polymerization SBR (random), solution polymerization SBR (random and styrene tapered)) other than the copolymer rubber of component (a), ethylene-propylene copolymer rubber (EP
M, EPDM), acrylonitrile-butadiene copolymer rubber (NBR) and the like. Further, among these, S, other than the polybutadiene rubber and the copolymer rubber of the component (a),
As the BR, those modified like the copolymer rubber of the component (a) can be used.

The Mooney viscosities (ML _{1 + 4} , 100 ° C.) of the rubbers of the components (a) and (b) are generally from 10 to 200, preferably from 30 to 100, more preferably from 45 to 80.
These rubbers can be used as an oil-extended rubber regardless of the Mooney viscosity before the oil-extension if the Mooney viscosity after the oil-extension is within the above range.

In the vibration damping rubber composition of the present invention, the blending ratio of the copolymer rubber of the component (a) and the diene rubber of the component (b) is such that the copolymer rubber of the component (a) is 5 to 95%. % By weight, preferably 20 to 60% by weight, and the diene rubber of the component (b) is 95 to 5% by weight, preferably 80 to 40% by weight. If the amount of the copolymer rubber of the component (a) in the rubber component is too small and the amount of the diene rubber of the component (b) is too large, the excellent anti-vibration properties at room temperature of the copolymer rubber of the component (a) will be obtained.
In many cases, it is difficult to maintain the durability and heat resistance, and when the amount of the copolymer rubber of the component (a) is too large and the amount of the diene rubber of the component (b) is too small, the anti-vibration properties at a low temperature, In many cases, it is difficult to improve soundproofing.

The plasticizer used in the present invention has a freezing point or a pour point of -50 ° C or lower, preferably -55 ° C or lower, more preferably -60 ° C or lower. If the freezing point or pour point is too high, the soundproofing properties of the anti-vibration rubber of the present invention may be insufficient, and it is usually difficult to obtain a plasticizer having a freezing point or pour point of -80 ° C or lower.

As such a plasticizer, for example, dioctyl phthalate (DOP), diisobutyl phthalate (D
Phthalates such as IBP) and diallyl phthalate (DAP); adipic esters such as dioctyl adipate (DOA), diisooctyl adipate (DIOA), diisodecyl adipate (DIDA) and benzyloctyl adipate; dioctyl azelate (DO)
Z), azelaic esters such as diisooctyl azelate (DIOZ); dioctyl sebacate (DOS)
And the like. Sebacic acid esters such as dioctyl dodecaneioate (DODN) and diisooctyl dodecaneioate; di-n-butylmaleate (DBM), dimethylmalate (DBM), dioctyl Maleic esters such as melate (DOM); fumaric esters such as dioctyl fumarate (DOF); triethyl citrate (TEC);
citrates such as n-butyl citrate; triethyl phosphate (TEP), tributyl phosphate (TBP), trioctyl phthalate (TOP, TO
F) and phosphoric esters such as tributoxyethyl phosphate (TBEP).

In the vibration-insulating rubber composition of the present invention, the ratio of the plasticizer to be added to the rubber component is appropriately determined according to the soundproofing properties and other properties required of the rubber. There is no particular limitation. Usually, rubber component 100
5 to 100 parts by weight per part by weight, preferably 10
The amount is from 70 to 70 parts by weight, and more preferably from 20 to 50 parts by weight. If the amount of the plasticizer is too small, the sound insulation may be insufficient. If the amount is too large, the strength may decrease and bleeding may occur.

The composition for vibration-isolating rubber of the present invention is obtained by mixing the above-mentioned rubber component and plasticizer with various compounding agents conventionally used for the production of vibration-isolating rubber by mixing a commonly used roll, Banbury or the like. It can be obtained by mixing and kneading using a machine. In the present invention, the type and amount of the compounding agent other than the rubber component and the plasticizer are not particularly limited, and can be appropriately determined so as to satisfy the performance required for the vibration-proof rubber. The above rubber components (a) and (b) may be used after being blended in advance, or may be mixed and kneaded with a compounding agent at the time of preparing the composition and blended at a predetermined ratio.

Commonly used compounding agents include vulcanizing agents, vulcanization accelerators, vulcanizing aids, reinforcing / filling agents, extender oils, processing aids, antioxidants, and antiozonants. These compounding amounts are usually, for example, 0.3 to 20 parts by weight of a vulcanizing agent, 0.1 to 10 parts by weight of a vulcanization accelerator, and 0 to 100 parts by weight of a reinforcing / filling agent with respect to 100 parts by weight of a rubber component. , Extension oil 0-100
Parts by weight, 0.1 to 5 parts by weight of an antioxidant.

Examples of the vulcanizing agent include sulfur, sulfur donating compounds such as tetramethylthiuram disulfide, and peroxides such as dicumyl peroxide. As the component rubber (b), natural rubber and polyisoprene rubber are used. When a diene rubber such as the above is used, sulfur is preferred from the viewpoint of durability. Examples of the vulcanization aid include zinc white and stearic acid. Examples of the vulcanization accelerator include guanidine-based, thiazole-based, sulfenamide-based, thiuram-based, dithioate-based, and thiourea-based vulcanization accelerators.

As the reinforcing / filling agent, for example, FEF,
Reinforcing agents such as carbon black such as SRF, silica, and clay are exemplified. Examples of the filler include calcium carbonate, magnesium silicate and the like. Among them, carbon black and silica are preferred. Examples of the extender oil include process oils such as aromatic oils, naphthenic oils, and paraffin oils. In the present invention, aromatic oils and naphthenic oils are preferred from the viewpoint of processability.

As the anti-aging agent, for example, poly-
(2,2,4-trimethyl-1,2-dihydroquinone)
Amine-ketones, such as N-phenyl-N'-isopropyl-p-phenylenediamine; 2,2 '
Examples of the phenolic antioxidant such as -methylenebis (4-ethyl-6-t-butylphenol) include waxes such as paraffin wax and carnauba wax.

The composition for a vibration-isolating rubber of the present invention obtained by mixing and kneading the above-mentioned rubber component, plasticizer and each compounding agent is molded and vulcanized by a method usually used in the production of a vibration-isolating rubber. By doing so, a vibration-proof rubber can be obtained. By using the composition for a vibration isolating rubber of the present invention, it is possible to produce a vibration isolating rubber for an automobile engine mount, a suspension bush and the like.

Finally, modification of the copolymer rubber of the component (a) and the copolymer rubber other than the component (a) of the component (b) and the polybutadiene rubber will be described. Modifications can be made to polymer chain ends and / or backbone. Hereinafter, the copolymer rubber of the component (a) will be described, but the same applies to the rubber of the component (b). The copolymer rubber of the component (a) obtained by the above-mentioned anionic polymerization has an active terminal at the polymer chain end unless a polymerization terminator such as alcohol such as methanol or ethanol or water is added to terminate the polymerization reaction. This is a so-called living polymer to which the above-mentioned catalytic metal having a bond is bonded.

When the terminal is modified, the active terminal metal of the living copolymer rubber and (A) a bond represented by the following general formula (1) (wherein X represents an oxygen or sulfur atom) are bonded in the molecular chain. And (B) one or more compounds selected from benzophenones and thiobenzophenones having an amino group and / or a substituted amino group. (In the formula, X is an oxygen atom or a sulfur atom.)

The compound (A) having a bond represented by the general formula (1) includes, for example, formamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N, N-dimethylacetamide, N, N-dimethylacetamide, N-diethylacetamide, aminoacetamide, N, N-dimethyl-N ', N'-dimethylaminoacetamide,
N ', N'-dimethylaminoacetamide, N'-ethylaminoacetamide, N, N-dimethyl-N'-ethylaminoacetamide, N, N-dimethylaminoacetamide, N-phenyldiacetamide, acrylamide, N, N- Dimethylacrylamide, N, N-dimethylmethacrylamide, propionamide, N, N-dimethylpropionamide, N, N-dimethyl-4-pyridylamide,

4-pyridylamide, benzamide, N-
Ethylbenzamide, N-phenylbenzamide,
N, N-dimethylbenzamide, N ', N'-(p-dimethylamino) benzamide, p-aminobenzamide, N ', N'-(p-diethylamino) benzamide, N '-(p-methylamino) benzamide N'-
(P-ethylamino) benzamide, N, N-dimethyl-N '-(p-ethylamino) benzamide, N, N-
Dimethyl-N ', N'-(p-diethylamino) benzamide, N, N-dimethyl-p-aminobenzamide,
N-methyldibenzamide, N-acetyl-N-2-naphthylbenzamide, succinamide, maleamide, phthalamide, N, N, N ', N'-tetramethylmaleamide, N, N, N ', N'-tetramethylphthalamide, succinimide, N-methylsuccinimide, maleimide, N-methylmaleimide, phthalimide,

N-methylphthalimide, oxamide,
N, N, N ', N'-tetramethyloxamide, N, N
-Dimethyl-p-amino-benzylacetamide, nicotinamide, N, N-diethylnicotinamide, 1,2
-Cyclohexanedicarboximide, N-methyl-1,
2-cyclohexanedicarboximide, methyl carbamate, N-methyl-methyl carbamate, N, N-diethyl-ethyl carbamate, ethyl carbanylate, p-
Amides and imides such as ethyl N, N-diethylamino-carbanilate; urea, N, N'-dimethylurea,
Ureas such as N, N, N ', N'-tetramethylurea, 1,3-dimethylethyleneurea, N, N'-diethylpropyleneurea, and N-methyl-N'-ethylpropyleneurea;formanilide; N-methylacetanilide, aminoacetanilide, benzanilide,

Anilides such as p, p'-di (N, N-diethyl) aminobenzanilide; δ-caprolactam, ε-caprolactam, N-methyl-ε-caprolactam, N-acetyl-ε-caprolactam, N- Vinyl-ω-laurylolactam, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N
-Vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, 2-piperidone, N-methyl-2-piperidone,
N-vinyl-2-piperidone, N-phenyl-2-piperidone, 2-quinolone, N-methyl-2-quinolone,
Lactams such as indolinone, N-methyl-2-indolinone; 3-diethyl-2-imidazolidinone,
-Methyl-3-ethyl-2-imidazoline dinone, 1-
Imidazolidinones such as methyl-3- (2-methoxyethyl) -2-imidazolidinone; isocyanuric acid,
Isocyanuric acids such as N, N ', N'-trimethylisocyanuric acid and the like and their corresponding sulfur-containing compounds. Particularly preferred compounds are compounds in which an alkyl group is bonded to nitrogen.

The benzophenones and thiobenzophenones (B) having an amino group and / or a substituted amino group include, for example, 4-aminobenzophenone, 4-dimethylaminobenzophenone, 4-dimethylamino-4 '
-Methylbenzophenone, 4,4'-diaminobenzophenone, 4,4'-bis (dimethylamino) benzophenone, 4,4'-bis (diethylamino) benzophenone, 4,4'-bis (ethylamino) benzophenone,
3,3'-dimethyl-4,4'-bis (diethylamino) benzophenone, 3,3'-dimethoxy-4,4 '
-Bis (dimethylamino) benzophenone, 3,3 ',
5,5'-tetraaminobenzophenone, 2,4,6-
Triaminobenzophenone, 3,3 ', 5,5'-tetra (diethylamino) benzophenone, and the like, and their corresponding thiobenzophenones. As the substituted amino group, those having an alkyl group are preferable, and a dialkyl-substituted amino group is particularly preferable. Substituents other than the amino group and substituted amino group may be present as long as they do not adversely affect the reaction.

The amount of the compound to be reacted with the living copolymer rubber may be equimolar or slightly excess with respect to the amount of the metal (the above-mentioned polymerization catalyst metal) bonded to the copolymer rubber. After completion of the reaction, a metal is removed by adding a coagulant which is also a polymerization terminator such as methanol to the reaction solution, or by blowing steam to coagulate steam while reacting the terminal with water which is a polymerization terminator, A terminal-modified copolymer rubber in which the above compound is bonded to the terminal is obtained.

Next, as a method for modifying the main chain of the copolymer rubber of the component (a) and the diene rubber of the component (b), for example, A method in which an alkali metal and / or an alkaline earth metal is added and reacted with the above compound is used. If terminal-modified SBR, BR, or the like is used, SBR, BR, or the like in which both the terminal and the main chain of the polymer chain are modified can be obtained. Another method of modifying the main chain is to use 2-N, N-dimethylaminostyrene, 4-N, N-method, when copolymerizing an amino vinyl-free aromatic vinyl monomer and butadiene as described above.
-Dimethylaminostyrene, 2-N, N-dimethylaminomethylstyrene, 4-N, N-dimethylaminomethylstyrene, aminostyrene, 2-vinylpyridine, 4-
Amino group-containing aromatic vinyl monomers such as vinyl pyridine, 2-vinyl (N, N-diisopropylbenzamide), 4-vinyl (N, N-diisopropylbenzamide), N, N-dimethylaminoethylstyrene and / or This is a method of copolymerizing other amino group-containing monomers.
Also, by reacting the above compound with a living polymer of the copolymer rubber, a copolymer rubber or BR having both main chain and terminal modified can be obtained.

In the present invention, the average amount of the bonded aromatic vinyl monomer in the copolymer rubber of the component (a) and the content of the 1,2 bonds in all butadiene units can be determined by the Hampton method using infrared spectroscopy. , Anal. Chem., Vol. 21, 923 (1949)).

[0040]

The present invention will be described more specifically below with reference to examples and comparative examples. The parts and percentages in the following examples are based on weight unless otherwise specified. The prevention characteristics were measured by the following method.

(1) Dynamic characteristics Hydraulic servo dynamic characteristic tester (EFH-20 manufactured by Sagimiya Seisakusho)
−50-2.5), the loss tangent (tan δ) at 23 ° C. and 15 Hz and the dynamic elastic modulus (K _d ) at 23 ° C. and 100 Hz were measured. divided by the _{K s) (K d / K} s), i.e., calculates the dynamic magnification. The measurement sample was a rubber vulcanizate having a diameter of 1 inch and a height of 2 inches.
tan δ and K _d are initially 2m with dynamic servo
m, and at 15 Hz, an amplitude of ± 0.5 mm,
At 100 Hz, measurement was performed with an amplitude of ± 0.05 mm. K _s is the displacement of the height of the sample is to compress at a rate of 1 mm / 15 seconds so that 2 mm, a compressed state depressurized after holding 30 seconds to restore the displacement 0 mm. This cycle is repeated three times, and the displacement during the third compression is 1 m
The elastic modulus was determined from the compressive stress during the period from m to 2 mm.
The larger the tan δ and the smaller the K _d / K _s (dynamic magnification), the better the vibration and soundproofing properties.

(2) Durability Test A crack growth test in a constant elongation fatigue test was performed using a Demasher bending tester. The constant elongation bending crack growth test was performed by JI
A B-type dumbbell described in S-K6301 and a test piece having a crack of 2.03 mm were subjected to an elongation rate of 10 using a demasher bending tester.
Attach it to 0%, reciprocate at 23 ° C at 300 times / min, and measure the length of the crack after 10,000 reciprocations. The smaller the crack length, the better the durability. (3) Physical properties under normal conditions Tensile strength (MPa), elongation at break (%), and hardness (using a JIS spring type A hardness tester) are measured according to JIS K6301.

Examples 1, 2 and Comparative Examples 1 to 5 The terminal-modified tapered SBR (average bound styrene content 20% by weight, 1,1% in all butadiene units) used in this example
2 bond content 65%, Mooney viscosity (ML _{1 + 4} , 100 ℃)
62) (SBR-1) was prepared by the following method.
In an autoclave with a stirrer whose internal volume is 15 liters,
8 kg of cyclohexane, 75 g of styrene, 925 g of 1,3-butadiene, 24 mmol of N, N, N ', N'-tetramethylethylenediamine were charged, and further,
A cyclohexane solution containing 18 mmol of n-butyllithium was added, and polymerization was started at 40 ° C. Start of polymerization 10
Minutes later, a mixture of 80 g of styrene and 520 g of 1,3-butadiene was continuously added over 20 minutes, and then a mixture of 150 g of styrene and 150 g of 1,3-butadiene was added for 1 minute.
It was added continuously over 5 minutes, and finally 100 g of styrene was added continuously over 15 minutes.

A portion of the reaction mixture was sampled at the time when 10% of all the monomers used had been polymerized from the start of polymerization (the portion forming one end of the total polymer chain length of 10%), and the resulting polymer was bound. When the amount of styrene was analyzed by infrared spectroscopy, it was 6.3%. Further, at the time when 90% of all the monomers used are polymerized and at the time when 100% are polymerized, the other end 10 of the total polymer chain length obtained from the difference in the amount of bound styrene of the sampled polymer, respectively.
The amount of bound styrene in the% portion was 48.9%.

After confirming that the polymerization conversion reached 100%, 1 mmol of tin tetrachloride was added and reacted for 20 minutes, and then 20 g of 1,3-butadiene was added to add 1 mmol.
After reacting for 0 minutes, 10 mmol of 4,4'-bis (diethylamino) benzophenone was added and reacted for another 30 minutes. After completion of the reaction, the reaction was stopped by adding 20 mmol of methanol. 2,6-di-
20 g of t-butyl-p-cresol (BHT) was added,
The modified SBR produced by steam stripping was coagulated, dehydrated with a dehydrating roll, and dried under reduced pressure at 60 ° C. for 24 hours.

According to the following formulation, the rubber component and the compounding agent other than the vulcanizing agent are mixed and kneaded with a Banbury mixer (0.8 liter), and the obtained mixture and the vulcanizing agent are mixed using a roll. And kneaded to produce a vulcanizable rubber composition. Specimen for measuring physical properties and durability under normal conditions (2 m thick)
m sheet) was produced by press vulcanization at 160 ° C. for 15 minutes. Also, a test piece (2 inches high x
A cylindrical block having a radius of 1 inch) was produced by press vulcanization at 160 ° C. for 20 minutes. Table 1 shows the evaluation results measured based on these test pieces.

Formulation rubber component (Table 1) 100 parts FEF carbon black 65 parts Zinc white 5 parts Stearic acid 2 parts Sulfur 1.8 parts Vulcanization accelerator (*) 1.2 parts Plasticizer or extender oil (Table 1) ) 50 parts (Note) (*) Noxeller CZ manufactured by Ouchi Shinko Chemical Co., Ltd.

[0048]

[Table 1] (Note) (1) Nipol BR1220 (high cis polybutadiene rubber) manufactured by Zeon Corporation (2) Dioctyl adipate (freezing point −60 ° C. or less) (3) Dibutyl phthalate (freezing point −35 ° C.) (4) Aromatics manufactured by Fujikosan System oil (pour point 10 ° C)

Example 1 is different from Comparative Example 1 in which a small amount of polybutadiene rubber was used instead of the copolymer rubber of the component (a) and a small amount of extender oil was used instead of the plasticizer of the component (2).
It has a small dynamic magnification, very good durability, and excellent heat aging resistance. Further, in Example 1, a comparison was made using only the diene rubber of the component (b) without using the copolymer rubber of the component (a), and using the same amount of extender oil instead of the plasticizer of the component (2). In comparison with Example 2, not only the dynamic magnification is small in dynamic characteristics, but also tan δ is small, and further excellent in durability,
Hardness change after heat aging is also small. Comparative Example 3 which is the same as Example 1 except that component (b) is used without using component (a)
Comparing Example 1 with Example 1, Example 1 is excellent in durability.

Example 1 is different from Comparative Example 4 which is the same as Example 1 except that a plasticizer having a freezing point higher than the range of the present invention is used as the plasticizer of the component (2). The tan δ and the dynamic magnification are small, and the change in elongation and the change in hardness are small in the heat aging resistance. Example 1
Compared with Comparative Example 5 which is the same as Example 1 except that an extender oil is used in place of the plasticizer of the component (2), tan δ and dynamic magnification are smaller in dynamic characteristics and durability is excellent. ing. Therefore, by using such a rubber composition of the present invention, vibration proof (tan δ) and sound proof (dynamic magnification) are obtained.
This makes it possible to produce an anti-vibration rubber excellent in durability and heat aging resistance.

[0051]

According to the present invention described above, it is possible to provide an anti-vibration rubber which is excellent in durability and heat resistance, and has a balance between anti-vibration and sound-proof properties. Such anti-vibration rubber can be used as anti-vibration rubber for engine mounts for automobiles, suspension bushes, and the like.

A preferred embodiment of the present invention is as follows. (1) In claim 1, the copolymer rubber (a) is a copolymer rubber of a living aromatic vinyl monomer having an active terminal and butadiene and (A) a bond represented by the following general formula (1). And (B) a reaction product with at least one compound selected from benzophenones and thiobenzophenones having an amino group and / or a substituted amino group. (In the formula, X is an oxygen atom or a sulfur atom.) (2) In claim 1 or (1), (a) has an average bound aromatic vinyl monomer amount of 15 to 30% by weight, based on all butadiene units. Is a copolymer rubber having a 1,2 bond content of 60% by weight or more. (3) In claim 1 or (1) or (2), (a)
Is 20 to 60% by weight, and (b) is 80 to 40% by weight. (4) In any one of claims 1, (1) to (3), the aromatic vinyl monomer is styrene. (5) In any one of claims 1, (1) to (4), (b) is at least one diene rubber selected from natural rubber, polybutadiene rubber, and random styrene-butadiene copolymer rubber. is there. (6) In any one of claims 1, (1) to (5), the use ratio of the plasticizer is 5 to 100 parts by weight, preferably 10 to 70 parts by weight, per 100 parts by weight of the rubber component. More preferably, it is 20 to 50 parts by weight.

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[Procedure amendment]

[Submission date] May 6, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

[Title of the Invention] Vibration-proof rubber composition and vibration-proof rubber

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // C08C 19/22 C08C 19/22 C08F 236/06 C08F 236/06 (C08F 236/06 212: 14)

Claims (2)

[Claims] (1) (1) (a) A copolymer rubber of an aromatic vinyl monomer and butadiene, which has an amino group and / or a substituted amino group, and has an average amount of the bonded aromatic vinyl monomer. 10
-40% by weight, the content of 1,2-bonds in all butadiene units is 50% by weight or more, and the amount of bound aromatic vinyl monomer increases or decreases from one end to the other along the polymer molecular chain 5 to 95% by weight of a copolymer rubber of an aromatic vinyl monomer and butadiene, and (b) a diene rubber 9 other than the above.
A composition for an anti-vibration rubber comprising: a rubber component consisting of 5 to 5% by weight; and (2) a plasticizer having a freezing point or a pour point of −50 ° C. or less. 2. An anti-vibration rubber obtained by molding and vulcanizing the composition according to claim 1.