JPH066639B2 - Rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrogenated polymer of a random copolymer composed of an aromatic vinyl compound and a diene compound.

Conventionally, as a hydrogenated polymer, for example, JP-A-56-30401,
57-2344, 56-30404, 56-30447, 56-30455 disclose hydrogenated polybutadiene. Hydrogenated products of styrene-butadiene block copolymers are also known.
However, although these hydrogenated polymers are generally improved in terms of aging resistance, they have not been satisfactory in terms of breaking strength and permanent set.

An object of the present invention is to provide a rubber composition containing a hydrogenated product of an aromatic vinyl compound / diene random copolymer, which has excellent aging resistance, good processability, and breaking strength.

According to the present invention, the content of the bound aromatic vinyl compound is 3 to.
An aromatic vinyl compound / diene random copolymer having a content of unsaturated bonds in the side chains of the diene portion of 70% by weight of 12% or more and 90% or less and a bimodal or trimodal pattern of the molecular weight distribution, A rubber composition comprising a copolymer hydrogenated to 30% or more and 90% or less of an unsaturated bond of a diene part, and another rubber component,
A rubber composition containing 20% by weight or more of the above copolymer is provided.

The aromatic vinyl compound / diene copolymer used in the present invention is advantageously produced by anionic polymerization.

As the aromatic vinyl compound, styrene, p-methylstyrene, m-methylstyrene, p-tertiarybutylstyrene, α-methylstyrene, chloromethylstyrene,
Examples include vinyltoluene and the like.

Preferred examples include styrene, p-methylstyrene,
Examples include α-methylstyrene.

As the diene compound, butadiene, isoprene, pentadiene, 2,3-dimethylbutadiene, etc. are used.

The anionic polymerization is performed under a known condition using a usual method, and an alkali metal or an alkaline earth metal can be used as a polymerization catalyst. Living polymerization using an organolithium compound catalyst is particularly preferable. In order to further contain a branched polymer as a high molecular weight region in the polymer, (i) further perform a coupling reaction after the polymerization reaction, or (ii)
In the polymerization, a polyfunctional monomer can be used as a copolymerization reaction.

Examples of the coupling agent using the coupling reaction include halides having at least trifunctional groups, ester compounds, epoxy compounds, aldehydes, ketone compounds, and the like.

Specifically, the halides include CCl ₄ , SiCl ₄ , RSi
Cl ₃ (where R is an alkyl group having 1 to 20 carbon atoms), SnC
Aliphatic halides such as l ₄ , GeCl ₄ , CBr ₄ , tetrachloroethane, and hexachlorobutadiene; charcoal aromatic halides such as trichlorobenzene, tribromobenzene, hexachlorobenzene, and hexabromobenzene; or
Various halogen-containing flame retardants are used.

As the ester compound, adipic acid diester, terephthalic acid ester, isophthalic acid ester, ethylene carbonate ester, propylene carbonate ester and the like are used.

As the epoxy compound, epoxidized liquid polybutadiene, epoxidized liquid polyisoprene, epoxidized soybean oil, epoxidized linseed oil and the like are used.

Examples of the polyisocyanate include benzene-1,2,4-triisocyanate and triphenylmethane triisocyanate.

As the polyfunctional monomer as the copolymerization component (ii), for example, divinylbenzene is used. The proportion of the polyfunctional monomer used is 0.02 to 5 parts by weight based on 100 parts by weight of all the monomers. If it exceeds this level, gelation occurs, and if it is less than this range, a branched polymer is difficult to obtain.

In the present invention, bimodal or trimodal means that the molecular weight distribution by gel permeation chromatography (GPC) gives a pattern in which two or three peaks are found. High molecular weight range, especially at least 3
In the case of a functional branched polymer, the molecular weight distribution is widened and the processability is large. The content of the branched polymer is not particularly limited, but it is preferably 20% by weight or more from the viewpoint of processability.

Next, the hydrogenated polymer is obtained by subjecting a solution of the above aromatic vinyl compound / diene random copolymer in an organic solvent to hydrogenation reaction under hydrogen pressure in the presence of a catalyst.

The reaction temperature is usually 20 to 150 ° C., and the pressure is not particularly specified, but a higher hydrogen pressure is preferable because the reaction is faster. The hydrogenation reaction time can be arbitrarily selected. As the hydrogenation reaction catalyst, palladium-carbon, reduced nickel, heterogeneous catalyst such as rhodium: nickel naphthenate,
Organic nickel compounds such as nickel octoate or cobalt naphthenates, organic cobalt compounds such as cobalt octoate and organoaluminum compounds such as triethylaluminum and triisobutylaluminum or n-
A homogeneous catalyst combining an organolithium compound such as butyllithium and sec-butyllithium can be used. As a co-catalyst, an ether compound such as tetrahydrofuran, ethyl glycol dimethyl ether, diethylene glycol dimethyl ether may be used.

The hydrogenated copolymer of the present invention has a content of the bound aromatic vinyl compound of 3-70% by weight, preferably 5 to 55% by weight, and a diene moiety having a side chain represented by a 1,2 or 3,4-vinyl structure. Content of unsaturated bond is 12% or more and 90% or less, preferably 6
It is a hydrogenated product of a polymodal random copolymer of 0% to 90%. When the content of the bound aromatic vinyl compound is less than 3% by weight, the breaking strength is low and not practical, while when it exceeds 70% by weight, the rubber-like property is lost and the strength is lowered, and the outer permanent strain is increased.

In addition, it is industrially difficult to obtain a polymer having a content of unsaturated bonds in the side chain of less than 12%, and since the balance of processability and physical properties is imparted to the hydrogenated polymer, the hysteresis loss is further increased. The unsaturated bond amount of the side chain is preferably 60% or more.

In the present invention, hydrogenation is 30% or more and 90% or less, preferably 50 to 9% of the unsaturated bond amount of the diene portion of the above copolymer.
It is performed at a rate of 0%. If the hydrogenation rate is less than 30%, the effect of improving weather resistance and heat resistance is insufficient, and it is preferable to increase the hydrogenation rate as much as possible. However, depending on the application, it is preferable to leave at least 10% of the unhydrogenated portion for vulcanization.

Further, when the hydrogenated polymer contains a branched polymer in the high molecular weight range, the processability is improved, and the hysteresis loss becomes large in addition to the aging resistance and the breaking strength, which makes it a suitable material for vibration damping materials. . It is considered that, when the branched polymer is introduced, when the molecular weight is the same as that of the straight-chain polymer, the free end chain is expanded and the hysteresis loss is increased.

The hydrogenated polymer of the present invention can be used alone or in a blend with another rubber component. Examples of such rubber include natural rubber, polyisoprene rubber, emulsion-polymerized styrene / butadiene rubber, solution-polymerized styrene / butadiene rubber, high vinyl polybutadiene, high vinyl unhydrogenated SBR and star polymer, butadiene / acrylonitrile rubber, Examples thereof include ethylene-propylene or ethylene-propylene-diene copolymer, butyl rubber and halogenated butyl rubber. In the case of blending, if the hydrogenated polymer is less than 20% by weight, the weather resistance, heat resistance and strength are not sufficiently improved.

If necessary, the composition of the present invention may be added with compounding agents usually used in the rubber industry such as carbon black, extender oil, sulfur, vulcanization accelerator, vulcanization aid, antiaging agent and the like.

The compounding and vulcanization reaction of the rubber composition is not particularly limited, and after the respective components are sufficiently compounded and mixed by a mixer such as a roll or Banbury, the compound can be vulcanized by an ordinary method such as a vulcanizing press.

The rubber composition of the present invention is used for various industrial products such as tire materials and anti-vibration rubber.

The present invention will be further described below with reference to examples. In the examples, the hydrogenation rate is H'at 100 MHz measured as follows.
-It is calculated from the decrease in the spectrum of the unsaturated bond part of NMR.
The solvent was measured using carbon tetrachloride at a concentration of 15% by weight. The amount of branched polymer was measured from the peak area of the polymer portion of GPC (gel permeation chromatograph manufactured by Waters). Column is STYRAGEL10 ⁶ , 10 ⁶ , 10
^{5, 10} 4 4-ft (× 4) tetrahydrofuran was used as a carrier used. Dunlop Rb was used as an index of hysteresis loss. This measuring method was based on BS903. The heat aging resistance was measured according to JIS K6301.

Example 5 2 degassed and dehydrated cyclohexane was added to an autoclave.
000g, styrene 100g, butadiene 400g
After charging, 5 g of tetrahydrofuran and 0.28 g of n-butyllithium were added to carry out polymerization. Polymerization temperature is 3
Polymerization was carried out at a temperature of 0 to 80 ° C. After the conversion reached almost 100%, 0.16 g of SiCl ₄ was added. Then 2,6-
Ditertiary butyl catechol was added to remove the solvent by the steam stripping method, and the sample was obtained by drying with a 120 ° C. hot roll.

By changing the monomer composition, the branching agent type, and the amount of tetrahydrofuran used in the same manner, the polymer of Sample BK in Table 1 before hydrogenation was obtained.

Various polymers having different bound styrene (%), vinyl content (%) of butadiene part, and branching agent species obtained above were charged into 3 autoclaves to prepare a 15% toluene solution. After substituting the system with nitrogen, a catalyst solution of nickel naphthenate: n-butyllithium: tetrahydrofuran = 1: 8: 20 (molar ratio) prepared in another container in advance was used as a polymer 1
It was charged so that 1 mol of nickel was obtained per 000 mol. Then, hydrogen was introduced into the reaction system, and the reaction was carried out at 60 ° C. After hydrogenating to the desired amount, remove hydrogen from the system with nitrogen and clean it to 5 ml.
Samples A to K were obtained by adding 2-6-ditert-butyl haracresol dissolved in the alcohol of 1. above, terminating the reaction, removing the solvent by a conventional method, and drying with a roll at 110 ° C.

The results are summarized in Table-1. The mixture was kneaded according to the formulation shown in Table 2 and vulcanized at 160 ° C. for 20 minutes. The results of workability and physical properties are shown in Table-3 and Table-4. The polymer of the present invention has an excellent balance of processability and physical properties. Comparative Examples-1, 2 and 3 are inferior to the Examples in breaking strength or workability. Comparative Example-4 is inferior in heat aging resistance. Furthermore, the hysteresis loss is inferior to that of the second embodiment. Similar results have been obtained in blends with other diene rubbers.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Noboru Oshima 2-11-24 Tsukiji, Chuo-ku, Tokyo Within Nippon Synthetic Rubber Co., Ltd. (72) Inventor Yoshihisa Fujinaga 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (72) Inventor Tatsuo Fujimaki 3-2-3 Fujimicho, Higashimurayama City, Tokyo Shin Musashino Sky Heights 613

Claims (4)

[Claims] 1. The content of bound aromatic vinyl compound is 3 to 7.
0% by weight and the content of unsaturated bonds in the side chain of the diene part is 1
Aromatic vinyl compound of 2% or more and 90% or less and having a bimodal or trimodal molecular weight distribution pattern /
A copolymer obtained by hydrogenating a diene random copolymer to 30% or more and 90% or less of the unsaturated bonds of the diene part,
And a rubber composition comprising another rubber component, the rubber composition containing 20% by weight or more of the copolymer. 2. A high molecular weight region in the aromatic vinyl compound / diene random copolymer is a branched polymer obtained by reacting a produced polymer with a coupling agent having three or more functional groups. The rubber composition according to claim 1. 3. The random copolymer, wherein the content of unsaturated bond in the side chain of the diene part of the random copolymer is 60% or more and 90% or less, and the content of bound aromatic compound is 5 to 55% by weight.
The rubber composition according to the item. 4. The hydrogenation ratio of the hydrogenated copolymer is 50.
The rubber composition according to claim 1, which is ˜90%.