GB2044277A - Process for producing a cyclopentadiene copolymer and a composition comprising said copolymer and a rubber - Google Patents

Abstract

A cyclopentadiene copolymer is produced by copolymerizing cyclopentadiene and a copolymerizable unsaturated hydrocarbon (which is preferably either a chain-conjugated diolefin or a monoolefin) using, as catalyst, a complex solution comprising a Lewis acid, an oxygen-containing electron donor and an aromatic hydrocarbon. This copolymer can be blended with a diene rubber (e.g. natural rubber or a styrene-butadiene copolymer rubber) to improve the properties of the rubber.

Description

SPECIFICATION Process for producing a cyclopentadiene copolymer and a composition comprising said copolymers and a rubber This invention relates to a process for producing a cyclopentadiene copolymer, as well as to a rubber composition obtainable from this copolymer and a diene type rubber.

More particularly, this invention relates to a process for obtaining a copolymer containing no gel and soluble in organic solvents in a high yield which comprises copolymerizing a cyclopentadiene and an unsaturated hydrocarbon copolymerizable therewith by the use of a catalyst consisting of a Lewis acid/oxygen-containing electron donor/aromatic hydrocarbon complex solution, as well as to a rubber composition improved in processability and tackiness of the unvulcanized rubber and markedly improved in mechanical properties of the vulcanized rubber which can be obtained by blending 4-40 parts by weight of the resin obtainable by said process, having a bromine number of 70-240, with 100 parts by weight of a diene type rubber and, if necessary, further blending the resulting mixture with carbon black, vulcanizing agent and so on.

In general, various process oils and plasticizers are used for the purpose of giving plasticity to rubbers and improving their processability. Although these materials can improve unvulcanized rubbers with regard to their processability and particularly plasticity, these materials have a problem that they lower the mechanical properties of vulcanized rubbers, such as tensile properties, hardness, cut resistance, etc., and their migration causes pollution and inhibits the bonding to cords. A variety of softening agents or plasticizers have hitherto been proposed for the purpose of improving these properties.

For example, it is disclosed to use styrene telomer (Nippon Gomu Kyokai-shi, 46, No. 10 (1973)), reaction product of sulfur monochioride and aromatic petroleum fraction (Japanese Patent Publication No. 8135/1972), chlorinated paraffin (Japanese Patent Publication No. 8340/1970), ethylene glycol dimethacrylate or oxystyrene and ester of poiybasic carboxylic acid (Japanese Patent Kokai (Laid-Open) No. 149337/1976) and the like as a reactive softening agent or plasticizer.

However, they are hardly in use practically because they are unsatisfactory for the reason of the corrosion of die by the hydrogen halogenide formed therefrom, the insufficient plasticizing effect, the scorching, etc. As an example of softening agent having less problem on rubber processing, petroleum resins mainly constituted of cyclopentadiene or dicyclopentadiene are disclosed in U.S.

Patent 3,927,144. However, vulcanized products of rubbers containing these petroleum resins as a softening agent are improved in physical properties insufficiently still. Further, the production at around room temperature of cyclopentadiene copolymer substantially free from gel resin has been difficult to perform hitherto.

That is, it has hitherto been disclosed to use tin tetrachloride, boron trifluoride, aluminum trichloride, titanium tetrachloride and the like as a catalyst for the copolymerization of cyclopentadiene and unsaturated hydrocarbons. However, when these catalysts are used, the polymerization reaction has to be carried out at a low temperature and, furthermore, gelation of the polymerization system is apt to occur so that the copolymerization reaction lacks uniformity. Therefore, these catalysts are poor in practicability for the industrial production of the copolymer.

As an improvernent thereof, there is disclosed in Japanese Patent Publication No. 30111/1975 a process for copolymerizing cyclopentadiene with conjugated diolefin by the use of a compound catalyst comprising allyl halide and an organoaluminum compound composed of trialkylaluminum and alkylaluminum halide. However, this process is stiil unable to overcome the above-mentioned disadvantages satisfactorily.

The present inventors conducted earnest studies on the process for producing a cyclopentadiene copolymer free from the above-mentioned faults and on the improvement of properties of rubber by the use of the resin thus obtained. As the result, there was found out a catalyst system with which the polymerization can be carried out in the neighborhood of room temperature without gelation in a high yield. In addition, it was found that the resin thus obtained can improve the processability and tackiness of unvulcanized rubber and can markedly improve the mechanical properties of vulcanized rubber.

Based on these findings, this invention was accomplished.

It is an object of this invention to provide a process for producing a cyclopentadiene copolymer containing no gel.

It is another object of this invention to provide a rubber composition comprising said copolymer and a diene type rubber.

Other objects and advantages of this invention will be apparent from the descriptions given below.

Thus, this invention provides a process for copolymerizing a cyclopentadiene with at least one member selected from the unsaturated hydrocarbons copolymerizable therewith by the use of a catalyst consisting essentially of a Lewis acid/oxygen-containing electron donor/aromatic hydrocarbon complex solution, as well as a rubber composition in which the processability and tackiness of unvulcanized rubber and the mechanical properties of vulcanized rubber can be improved markedly by blending 4-40 parts by weight of the resin obtainable by this process, having a bromine number of 70-240, with 100 parts by weight of a diene type rubber.

As the cyclopentadienes usable in this invention, cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, dimethyicyclopentadiene and the like can be referred to, though they are mentioned in no limitative way. They can be used either alone or in the form of a mixture.

Said unsaturated hydrocarbons include monoolefins, diolefins and the like and ar enot particularly limited so far as they are copolymerizable with cyclopentadienes. Concrete examples of said unsaturated hydrocarbons include 1 -butene, 2-butene, isobutylene, 1 -pentene, 2-pentene, I -hexene, 2- hexene, butadiene, isoprene, piperylene, cyclopentene, cyclooctene, 1 ,3-cyclooctadiene, dicyclopentadiene, styrene, a-methylstyrene, vinyltoluene, indene and the like. They may be used either alone or in the form of a mixture.Among them, chain conjugated diolefins and C4-C5 monoolefins are preferable, and chain conjugated diolefins such as butadiene, isoprene, piperylene and the like are preferable particularly when a resin of high unsaturation is intended for the purpose of improving the reactivity with rubber. Among the monoolefins, isobutylene is particularly preferable.

Further, a C5 fraction comprising unsaturated hydrocarbons having 5 carbon atoms and having a main boiling point range of 0--700C taken from the cracked oil formed by the thermal or catalytic cracking of petroleum fractions such as naphtha, kerosene, light oil and heavy oil or a crude petroleum oil can also be used.

Though the proportion of said cyclopentadiene to said unsaturated hydrocarbon mixed therewith may be arbitrary and any proportion may be-selected in accordance with the performances and properties required of the copolymer, the amount of cyclopentadiene is usually 598% by weight-and preferably 35% by weight or more based on the total monomer. Particularly, this invention can be practised without difficulty even in the copolymerization of monomer mixture containing 5% by weight or more of cyclopentadienes of which copolymerization has been difficult to do hitherto.

The copolymerization catalyst used in this invention for copolymerizing a cyclopentadiene with an unsaturated hydrocarbon copolymerizable therewith is a solution type complex catalyst of high uniformity consisting of a Lewis acid, an oxygen-containing electron donor and an aromatic hydrocarbon.

If a Lewis acid which is usually solid is used alone as a catalyst for copolymerizing a cyclopentadiene and an unsaturated hydrocarbon, gelation takes place in the course of polymerization and the only product is a polymer insoluble in organic solvents. However, by adding an oxygencontaining electron donor to such Lewis acid and further adding an aromatic hydrocarbon to-give a solution type catalyst system for the sake of making it a catalyst solution of higher uniformity, no gelation takes place in the course of polymerization and a copolymer soluble in organic solvents can be obtained in a high yield.

The Lewis acids usable in this invention are metal halides generally employed as Friedel Crafts type polymerization catalyst, such as aluminum trichloride, aluminum tribromide, titanium tetrachloride, titanium tetrabromide, tin tetrachloride, tin tetrabromide, boron trifluoride and the like, among which aluminum trichloride is preferable.

As said oxygen-containing electron donors, water and oxygen-containing organic compounds can be referred to. Typical examples of the oxygen-containing organic compounds include epoxide compounds such as propylene oxide and butadiene monoxide; monohydric and polyhydric alcohol compounds such as methyl alcohol, ethyl alcohol, n-butyl alcohol, ethylene glycol and glycerin; phenolic compounds such as phenol; aliphatic, aromatic and alicyclic carboxylic acids such as acetic acid, propionic acid, benzoic acid and cyclohexanecarboxylic acid or acid anhydrides thereof; polybasic carboxylic acids such as succinic acid and maleic acid or acid anhydrides thereof; carboxylic esters obtainable from carboxylic acid and alcohol or phenolic compound such as ethyl acetate, ethyl benzoate and dimethyl succinate; cyclic esters such as -caprolactone; ketone compounds such as acetone, methyl ethyl ketone and cyclopentanone; ether compounds such as diethyl ether, di-n-butyl ether, diphenyl ether and tetrahydrofuran; and the like. Among them, alcohol compounds and ether compounds are preferable. These compounds have at most 20 carbon atoms in general, and those having 1 8 or less carbon atoms are particularly preferable. They may be used either alone or in combination of two or more kinds. Among them, ethyl alcohol, butyl alcohol, diethyl ether, dibutyl ether and tetrahydrofuran are particularly preferred.

As the aromatic hydrocarbons usable in this invention, benzene, toluene, xylene, ethylbenzene, propylbenzene, hemimellitene, pseudocumeme, mesitylene and mixtures thereof can be referred to, among which toluene, ethylbenzene, xylene, mesitylene and mixtures thereof are preferable.

The proportion of oxygen-containing electron donor to Lewis acid varies with the kind of Lewis acid and oxygen-containing compound used, and it is appropriately selected from such a range as to give a uniform catalyst solution and a catalyst activity, with consideration of the kind and composition of monomer. The amount of oxygen-containing compound is usually in the range of 0.5-5.0 moles and preferbly in the range of 0.8-3.0 moles per one mole of Lewis acid. If it is less than 0.5 mole, no uniform complex solution catalyst is obtainable or no soluble copolymer is obtainable. If it exceeds 5.0 moles, the activity of catalyst so markedly drops that no copolymer is obtainable sometimes, and such a catalyst is poor in industrial vaiue. The aromatic hydrocarbon is also used in such a range as to give a uniform catalyst solution. Its amount is usually in the range of 1.0-1 0 moles and preferably in the range of 2.5-6.0 moles per one mole of Lewis acid. If th9 amount of aromatic hydrocarbon is less than 1.0 mole or greater than 10 moles, a uniform complex solution is difficult to obtain sometimes. Such a catalyst is not suitable for the object of this invention.

The method for preparing catalyst is not particularly limited, and any method may be employed so far as a uniform Lewis acid/oxygen-containing electron donor/aromatic hydrocarbon complex solution can be obtained. For example, it can be prepared easily by reacting a Lewis acid with an oxygen containing compound in an aromatic hydrocarbon with stirring.

The amount of catalyst used is appropriately decided on the bsis of yield and characteristic properties of the copolymer to be obtained, with consideration of the kind and composition of monomer.

The amount of catalyst is usually in the range of 0.115.0% by weight and preferably in the range of 0.3-10.0% by weight in terms of the quantity of Lewis acid based on monomer. If the quantity of Lewis acid is less than 0.1 % by weight, the yield is low and a gel forms readily. If it exceeds 15.09/0 by weight, there arises an economical disadvantage and the molecular weight of the resulting copolymer drops.

Though the polymerization of this invention can be pradtised even in the absence of any inert organic solvent, it is more preferable to use such a solvent in order to facilitate the control of reaction.

Typical examples of said solvent include aromatic hydrocarbons such as benzene, toluene, ethyl benzene and xylene; aliphatic hydrocarbons such as n-pentane, hexane and heptane; alicyclic hydrocarbons such as cyclohexane; halogenated hydrocarbons such as methylene dichtoride, dichloroethane, dichloroethylene, tetrachlornethane, chlorobenzene; dichlorobenzene and trichiornbenzene; and the like. These solvents may be used either alone or in the form of solvent mixture.

The Polymerization is usually carried out by dissolving a monomer into a solvent and then adding a catalyst solution. Though the concentration of monomer is not particularly limited, a monomer concentration of 560% by weight is usually preferable.

The order in which cyclopentadiene, unsaturated hydrocarbon, catalyst and-inert solvent are added may be selected arbitrarily and is not particularly limited.

The polymerization reaction is carried out at an arbitrary temperature between -50oC and + 100 C and preferably between OOC and 900 C, under an ordinary or elevated pressure, and in an atmosphere of inert gas. Though the duration of polymerization is not particularly limited, it is 5 minutes to 10 hours.

The polymerization of this invention may be carried out by any polymerization processes such as batch polymerization, semi-batch polymerization, continuous polymerization and the like.

After completion of the polymerization reaction, the polymerization is stopped by, for example, contacting the reaction mixture with an alcohol, after which the catalyst is removed by the usual treatment such as washing with alkali, and subsequently the unreacted compounds and solvents are removed by distillation, concentration or the like. Otherwise, the reaction mixture is thrown into a lower alcohol. By these procedures, the intended copolymer can be obtained.

The copolymer obtained according to this invention has some properties. unobtainable hitherto in that it contains no gei, it is readily soluble in hydrocarbon solvents such as toluene, it is a transparent resin, it has a high degree of unsaturation and it is rich in reactivity. If necessary, further excellent properties can be given to it by incorporating usually employed antioxidant, ultraviolet absorber, heat stabilizer, plasticizer, filler and the like, into it.

When incorporated with a diene type rubber, the cyclopentadiene copolymer obtained by the above-mentioned production process can improve the processability and tackiness of unvulcanized rubber and can markedly improve the mechanical properties of vulcanized rubber.

The diene type rubbers usable in this invention include natural rubber, styrene-butadiene copolymer rubber, polyisoprene rubber, polybutadiene rubber, polychloroprene rubber, isoprene isobutylene copolymer rubber, acrylonitrile-butadiene copolymer rubber and the like. They may be used either alone or in the form of mixture.

In order that the cyclopentadien copolymer obtained by the production process mentioned above can exhibit an effectiveness on the properties of vulcanized rubber, they must have a bromine number of 70-240, preferably 80-240, and more preferably 1 50-240, with consideration of the reactivity of their double bond. If the bromine number is less than 70, they are low in reactivity and limited in co vulcanization effect with rubber. On the other hand, production of a resin having a bromine number greater than 240 is difficult.

Though softening point of said resin is not particularly limited if the conditions of rubber compounding and processing are taken into consideration, it is usually 2000C or lower and preferably 1 500C or lower. If it exceeds 2000 C, the resin is poor in plasticizing effect and ineffective for the improvement of processability.

Though the ratio at which said resin is blended with rubber varies depending on the use and object, it is in the range of 4-40 parts by weight of resin per 100 parts by weight of diene type rubber from the viewpoint of processabiiity and properties of vulcanized rubber. Formulating ingredients generally employed in the rubber industry such as carbon black, sulfur, vulcanization accelerator, vulcanization assistants and the like are added to this mixture, and then it can be vulcanized. The amount of carbon black incorporated is 1 0-200 parts by weight per 100 parts by weight of diene type rubber.

Since the rubber composition of this invention is a blend of a resin substantially containing no gel, it is excellent in miscibility with rubber and improved in processability. In addition, since the resin contains cyclopentadienes excellent in reactivity, it is excellent in co-vulcanizing reactivity with rubber, can improve the mechanical strength of vulcanized rubber, is free from the problem of migration such as that experienced in case of process oils, and has a good balance between physical properties.

Having these excellent properties, the rubber composition of this invention can be used as a rubber for automobile tires (particularly tire tread) and other industrial and general articles.

With reference to the following examples, this invention will be illustrated more concretely. This invention is by no means limited by these examples. Among the properties of resin, softening point was measured by ring and ball method in accordance with JIS K 2531, the number average molecular weight was measured by means of vapor pressure osmometry, and the bromine number was measured by a method in accordance with JIS K2543. In examples, percents and parts are all by weight.

EXAMPLES 1-3 33.4 g of aluminum trichloride and 88.0 g of xylene were charged into a 300 ml glass reactor equipped with a thermometer, a reflux condenser, a dropping funnel and a stirrer after replacement with nitrogen. While stirring the charged materials at 400 C, 36.5 g of a solution of diethyl ether in xylene (18.5 g of diethyl ether and 18.0 g of xylene) was dropped from the dropping funnel in 30 minutes. After stirring for an additional one hour, there was obtained aluminum trichloride-diethyl ether-xylene solution catalyst (aluminum trichloride/diethyl ether/xylene = 1/1/4 by mole).

For polymerization, cyclopentadiene and isoprene were charged in the proportion shown in Table 1 together with 110 ml of an hydros toluene into a 300 ml glass reactor equipped with a thermometer, a stirrer, and a reflux condenser after replacement with nitrogen. Then 2.3 g of the catalyst solution prepared above (as aluminum trichloride, 3.0% based on the monomer charged) was added and the mixture was reacted at 250C for one hour. After completion of the reaction, methanol was added to stop the polymerization and 0.1 g of 2,6-di-tert.-butyl-4-methylphenol was added as a stabilizer. The mixture was washed with aqueous solution of sodium hydroxide and water, the oily layer was separated from the aqueous layer, and the unreacted monomer and the solvent were distilled off from the oily layer to obtain a light yellow resinous copolymer.Yields and properties of the copolymer are shown in Table 1.

TABLE 1

Example 1 j 2 1 3 Cyclopentadiene (g) 8.2 4.1 12.3 Monomer Isoprene (g) 8.2 12.3 4.1 charged Cyclopentadiene I Isoprene (ratio by %) 50/50 25/75 75/25 Yield (%) 85 81 92 Softening point ("C) 93 67 123 Properties Number average of molecular weight 1900 1500 2700 copclymer -- Bromine number 165 140 180 Solubility in toluene Soluble Soluble Soluble The results shown above demonstrate that, in any of Examples 1-3, a copolymer of cyclopentadiene and isoprene was obtained in a high yield and the copolymer was substantially soluble in organic solvent.

EXAMPLE 4 The procedure of Example 1 was repeated, except that 2.33 g of aluminum trichloride-diethyl ether-xylene solution catalyst (aluminum trichloride/diethyl ether/xylene = 1/4/2 by mole) prepared by the same procedure as in Example 1 was used as a catalyst for the polymerization. A copolymer having a softening point of 78 C, a number average molecular weight of 1,450 and a bromine number of 1 75 was obtained in a yield of 42%. It contained no gel at all and was completely soluble in toluene.

EXAMPLE 5 The procedure of Example 2 was repeated, except that 2.19 g of aluminum trichloride-diethyl ether-xylene solution catalyst (aluminum trichloride/diethyl ether/xylene = 1/0.6/4 by mole) prepared by the same procedure as in Example 1 was used as a catalyst for the polymerization. A copolymer having a softening point of 11 00C, a number average molecular weight of 1,700 and a bromine number of 145 was obtained in a yield of 96%. It was soluble in toluene and contained no gel.

EXAMPLES 6-9 Copolymers were prepared by repeating the procedure of Example 1 except that the isoprene used in Example 1 was replaced by the unsaturated hydrocarbons shown in Table 2. Yields and properties of the copolymers are shown in Table 2.

TABLE 2

Example 6 7 8 9 Monomer charged Unsaturated hydrocarbon Butadiene Piperylene Isobutylene Styrene Yield (%) 68 88 82 95 Softening point ("C) 73 70 95 120 Properties of Number average 1,300 1,500 2,500 2,200 copolymer molecular weight Bromine number 170 170 130 95 Solubility in toluene Soluble Soluble Soluble Soluble EXAMPLES 10-13 In the preparation of catalyst solution mentioned in Example 1, the diethyl ether was replaced by the oxygen-containing compounds shown in Table 3. By preparing catalyst and conducting polymerization under various conditions, there were obtained copolymers. The results are shown in Table 3.

TABLE 3

Example 10 11 12 13 Oxygen-containing Di-n-butyl Ethyl n-Buthyl Tetrahydro compound ether alcohol alcohol furan Preparation of catalyst Aluminium trichloride/ oxygen-containing 1/1 1/1 1/1 1/0.8 compound (ratio by mole) Cyclopentandiene/ isoprene (ratio by %) 50/50 50/50 50/50 50/50 Amount of catalyst (% of aluminium tri Polymerization chloride on 3.0 2.0 2.0 3.0 monomer) Temperature of poly merization ( C) 50 25 25 35 Duration of poly merization (hr) 1 1 1 2 Yield (%) 87 97 98 80 Softening point ( C) 132 108 95 85 Properties of Number average copolymer molecular weight 2,500 2,000 2,200 1,550 Bromine number 160 165 170 175 Solubility in toluene Soluble Soluble Soluble Soluble EXAMPLE 14 The procedure of Example 11 was repeated except that the charged monmers were 4.1 g of cyclopentadiene, 4.1 g of isoprene and 8.2 g of isobutylene.A copolymer having a softening point of 51 OC, a number average molecular weight of 1,650 and a bromine number of 120 was obtained in a yield of 88%. It was soluble in toluene and contained no gel at all.

EXAMPLE 15 A cyclopentadiene-isoprene copolymer was obtained by repeating the procedure of Example 1, except that the xylene was replaced by ethylbenzene in the preparation of catalyst solution mentioned in Example 1. Its yield was 82%. It had a softening point of 91 C, a number average molecular weight of 1,850 and a bromine number of 1 70. It was completely soluble in toluene.

COMPARATIVE EXAMPLE 1 In Example 1,0.8 g of 10% triethylaluminumxylene solution and 0.5 g of allyl chloride were added as catalyst in place of the aluminum trichloride-diethyl ether-xylene solution catalyst and the polymerization was started at 25 C. After about 50 minutes, a rapid exothermic reaction took place to form a gel. The polymer obtained was insoluble in toluene.

COMPARATIVE EXAMPLE 2 The procedure of Example 1 was repeated, except that 1.52 g of aluminum trichloride/hydrogen chloride/xylene solution catalyst (1/0.5/2 by mole) containing hydrogen chloride in place of diethyl ether was used as a catalyst. A large quantity of gel was formed just after the start of polymerization and no copolymer soluble in.organic solvent was obtained.

COMPARATIVE EXAMPLE 3 The procedure of Example 1 was repeated, except that the polymerization.was carried out by using 3.64 g of a catalyst solution (aluminum trichloride/diethyl ether/xylene = 1/6/4 by mole) prepared by using 111 g of diethyl ether in place of its 18.5 g in the preparation of catalyst solution mentioned in Example 1. As the result, the yield was so low as 2%, though no formation of gel was observed.

-COMPARATIVE EXAMPLE 4 In the preparation of catalyst solution in Example 1, the amount of diethyl ether was changed from 18.5 g to 1.85 gIn the catalyst thus prepared (aluminum trichloride/diethyl ether/xylene = 1/0.1/4 by mole) alumirrnm trichloride did not dissolve, so that no uniform catalyst solution was obtained.

Polymerization was carried out in the same manner as in Example- 1 by the use of2.06 g of this heterogeneous catalyst. A large quantity of gel was formed just after the start of polymerization, and no copolymer soluble in organic solvent was obtained.

COMPARATIVE EXAMPLE 5 The procedure of Example 1 was repeated, except that the polymerization was carried out by using 1.35 g of aluminum trichloride-ethyl acetate-xylene solution catalyst (aluminum trichloride/ethyl acetate/xylene = 1/0.3/2) prepared by the same procedure as in Example 1 by using ethyl acetate in place of the diethyl ether. A gel was formed in the course of polymerization and no copolymer soluble in organic solvent was obtained.

EXAMPLES 16-(1)-(8) AND COMPARATIVE EXAMPLES 6-(1)-(2) (A) Resins AB (a) 33.4 g of aluminum trichloride and 88.0 g of xylene were charged into a 300 ml glass reactor equipped with a thermometer, a reflux condenser, a dropping funnel and a stirrer after replacement with nitrogen. While stirring the materials at 400C, 36.5 g of diethyl ether-xylene solution (18.5 g of diethyl ether and 1 8.0 g of xylene) was dropped from the dropping funnel in 30 minutes. After stirring the mixture for an additional one hour, there was obtained an aluminum trichloride-diethyl ether-xylene solution catalyst (aluminum trichloride/diethyl ether/xylene = 1/1/4 by mole).

(b) For polymerization, cyclopentadiene monomer and isoprene monomer (100 g in the total) were charged in the proportion shown in Table 4 together with 500 ml of anhydrous toluene into a 1 liter glass reactor equipped with a thermometer, a stirrer and a reflux condenser after replacement with nitrogen. Then, 14.2 g of the catalyst solution prepared above (3.0% in term of the quantity of aluminum trichloride, based on the monomer charged) was added and the mixture was reacted at 300C for one hour. After completion of the reaction, methanol was added to stop the polymerization, and 0.1 g of 2,6-di-tert-butyl-4-methylphenol was added as a stabilizer.The mixture was washed with aqueous solution of sodium hydroxide and water, the oily layer was separated from the aqueous layer, and the unreacted monomer and the solvent were distilled off from the oily layer to obtain a light yellow resin (referred to as "resin A-B"). Yields and properties of these resins are shown in Table 4.

(B) Resin C An aluminum trichloride-ethyl alcohol-xylene solution catalyst was prepared in the same manner as in (A)-(a), except that ethyl alcohol was used in place of the diethyl ether. By carrying out polymerization in the same manner as in (A)-(b) with said catalyst, a light yellow resin (referred to as "resin C") was obtained. Properties of this resin are shown in Table 4.

(C) Resins D-G Resins (referred to as "resins D-G") were obtained by carrying out polymerization in the same manner as in (A)-(b), except that the unsaturated hydrocarbons shown in Table 4 were used in the same amount as the amount of cyclopentadiene in place of the isoprene. Properties of these resins are shown in Table 4.

TABLE 4

Resin A B C D E F G Cyclopentadienes (I) CPD* CPD* CPD* CPD* CPD* CPD* CPD* Monomer Unsatured hydrocomposition carbons (II) Isoprene Isoprene Isoprene Butadiene Piperylene Isobutylene Styrene (I)/(II) (by %) 50/50 20/80 50/50 50/50 50/50 50/50 50/50 Yield (%) 88 83 96 73 92 86 94 Softening point ( C) 95 76 112 79 85 93 122 Properties of Number average resin molecular weight 2,050 1,700 2,150 1,450 1,900 2,700 2,350 Bromine number 170 135 165 170 165 130 100 Solubility in toluene Soluble Soluble Soluble Soluble Soluble Soluble Soluble * CPD: Cyclopentadiene (D) Rubber Composition To the compound mixture mentioned below, the above-mentioned resin, a process oil as a conventional softening agent for SBR and a petroleum resin were added in the proportion shown in Table 5 per 100 parts of styrene-butadiene copolymer rubber (SBR). The resulting mixture was blended and kneaded with a roll mill. Mooney viscosity of the unvulcanized rubber was measured according to JIS K 6300 to evaluate its plasticity. Three days after the kneading, tackiness of the unvulcanized rubber was evaluated by using a Monsanto Tel-Tak.

This blended rubber composition was vulcanized at a temperature of 1 500C for a time period of 40 minutes to obtain a vulcanized rubber, and it was subjected to tensile test, impact cut test and extractability test.

The tensile test was carried out in accordance with JIS K 6301. The impact cut test was carried out by dropping a knife having a sharp edge onto the sample from a height of 20 cm with a load of 10 kg. The relative depth of the cut on each sample was expressed by an index, taking the depth of cut on the sample of Comparative Example 6(1) containing process oil as 100. It is generally said that this test corresponds to the cut property of tire tread occurring when driven on rough roads.

Since all the resins were soluble in chloroform, the extractability test was carried out by extracting a sample with chloroform for 48 hours in a Soxhlet extractor. By taking the extraction in a standard sample to which nothing was added as zero and taking the extraction in the sample of Comparative Example 6-( 1) to which process oil was added as 100, the results obtained were employed for expressing the co-vulcanization reactivity between each resin and rubber.

Compounded mixture: SBR 1 500 (manufactured by Sumitomo chemical Co.) 100 parts HAF Black 50.0 ZnO 5.0 Stearic acid 3.0 Sulfur 2.0 Soxinol) CZ (manufactured by Sumitomo Chemical Co.) 1.0 The results of the test are summarized in Table 5.

TABLE 5

Example 16 (1) (2) (3) (4) Composition Resin added Resin A Resin A Resin B Resin C of rubber Amount (parts) 10 20 10 10 Properties of Mooney viscosity 55 47 50 56 unvulcanized ML1+4 (100 C) rubber Tackiness (g/14 mm) 300 340 310 300 Tensile strength 240 223 243 238 (kg/cm) Elongation (%) 385 395 390 390 Properties of 300% Modulus (kg/cm) 202 200 200 208 vulcanized rubber Hardness 72 74 68 71 Cut resistance )index) 42 40 58 45 Extractibility (%) 9 13 27 8 TABLE 5 (Continued)

Comparative Example 6 Standard (5) (6) (7) (8) (1) (2) Example Resin D Resin E Resin F Resin G Process oil Note 1) Petroleum resin Note 2) None 10 10 10 10 10 10 52 54 56 58 52 53 64 310 300 290 270 190 320 300 235 245 206 230 242 253 220 380 390 320 350 390 450 310 207 196 187 204 153 130 205 67 66 69 70 62 63 68 55 51 62 68 100 98 65 8 9 28 33 100 100 0 Note 1) Sundex # 790 manufactured by Sun Oil Co.

Note 2) Escorez # 1102B manufactured by Esso Chemical Co., aliphatic petroleum resin comprising C5 fraction, softening point 100 C, molecular weight 1,400, bromine number 40.

COMPARATIVE EXAMPLE 7 The same procedure as in the case of Resin (A) of Example 1 6 was repeated, except that, in (A)-(a) of Example 16, an aluminum trichloride-hydrogen chloride-xylene solution catalyst (1/0.5/2 by mole) containing hydrogen chloride in place of the diethyl ether was used. A large quantity of gel was formed just after start of the polymerization.

Since the polymerized oil was difficult to wash, it was directly dried in vacuum for the sake of removing the unreacted matter and the solvent. The polymer obtained was insoluble in toluene and showed no tendency of softening in the temperature range up to 2000 C. Pulverized product of said polymer was blended with SBR and kneaded in the same manner as in Example 1 6-(D). However, it was difficult to disperse and dissolve this product uniformly into rubber.

EXAMPLE 1 7-( 1 )-(3), AND COMPARATIVE EXAMPLE 8-( 1 )-(2) The same test as in Example 1 6-(1) (5) and (6) was carried out on natural rubber (NR) systems.

As the compounded mixture, that having the following formulation was used: Compounded mixture: NR 100 parts HAF Black 45.0 ZnO 5.0 Stearic acid 3.0 Sulfur 2.0 Soxinol CZ (manufactured by Sumitomo Chemical Co.) 1.0 " The resins added and the results of the test are summarized in Table 6.

TABLE 6

Example 17 Comparative Example 8 Standard (1) (2) (3) (1) (2) Example Process Petroleum Composition Resin added Resin A Resin D Resin E oil resin None of Note 3) Note 4) rubber Amount (parts) 10 10 10 10 10 Properties Mooney viscosity 25 21 22 22 23 32 of ML1+4(100 C) vulcanized rubber Tackiness (g/14 mm) 700 730 710 540 720 700 Tensile strength (kg/cm) 278 271 286 250 243 274 Elongation (%) 505 510 530 575 605 490 Properties of 300% Modulus 138 135 132 93 64 142 vulcanized (kg/cm) rubber Hardness 70 66 65 62 61 68 Cut resistance 48 56 60 100 110 55 (index) Extractibility (%) 13 17 15 100 93 0 Note 3) Tamasof # manufactured by Arakawa Chemical Co.

Note 4) Escorez # 1102B manufactured by Esso Chemical Co, (the same as Note 2).

EXAMPLE 18 AND COMPARATIVE EXAMPLE 9-(1) AND (2) (A) Resin H 250 g of a C5 petroleum fraction having a principal carbon number of 5 and a boiling point range of 0--700C (it is constituted of 42.1% of paraffins,24.2% of monoolefins and 33.7% of diolefins comprising 12.5% of isoprene, 13.0% of cyclopentadiene and 1.8% of dicyclopentadiene) was charged into a 500 ml glass reactor equipped with a thermometer, a reflux condenser and a stirrer after replacement with nitrogen. Then 17.7 g of a solution catalyst prepared by the method mentioned in Example 1 (it corresponded to 1.5% of aluminum trichloride based on the starting-oil) was added as a catalyst, and the mixture was reacted at 250C for one hour.After completion of the reaction, the procedure of the Example 1 was repeated to obtain 65 g of a resin having a number average molecular weight of 2,100, a softening point of 930C and a bromine number of 135. This resin is referred to as "Resin H".

(B) Resin I The procedure of Example 1 8 (A) was repeated, except that a C5 fraction from which the major part of cyclopentadiene had been removed by a heat treatment (it was constituted of 48.8% of paraffins, 28.7% of monoolefins and 22.5% of diolefins comprising 14.8% of isoprene and 0.8% of cyclopentadiene) was used as the starting oil and 10.2 g of the same catalyst as used in Comparative Example 2 was used as the catalyst. Thus, 90 g of a resin having a number average molecular weight of 1,300, a softening point of 960C and a bromine number of 60 was obtained. It was soluble in toluene and contained no gel. This resin is referred to as "Resin I".

(C) Rubber Composition The same test as in Example 1 6-(D) was practised on resins (H) and (I). Similarly to Example 1 7-(1) to (3), the compounded mixture used was that of natural rubber type formulation. The results are summarized in Table 7.

TABLE 7

Comparative Comparative Standard Example 18 Example 9-(1) Example 9-(2) Example Resin added Resin H Resin I Process oil None Composition of rubber Amount (parts) 10 10 10 Properties Mooney viscosity, 22 24 20 31 of ML1+4(100 C) vulcanized rubber Tackiness (g/14 mm) 740 740 540 710 Tensile strength 282 240 242 287 (kg/cm) Elongation (%) 470 590 550 440 Properties 300% Modulus 137 72 95 152 of (kg/cm) vulcanized rubber Hardness 67 62 62 69 Cut resistance 59 105 100 51 (index) Extractibility (%) 25 95 100 0 Note 5) Tamasof # manufactured by Arakawa Chemical Co.

Claims (23)

1. A process for producing a cyclopentadiene copolymer in which cyclopentadiene is copolymerized.with at least one copolymerizable unsaturated hydrocarbon in the presence of a catalyst comprising.a Lewis acid/oxygen-containing electron donor/aromatic hydrocarbon complex solution.

2. A process according to Claim 1, in which said cyclopentadiene is cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene or dimethylcyclopentadiene.

3. A process according to Claim 1, in which said cyclopentadiene is cyclopentadiene itself.

4. A process according to any one of the preceding Claims, in which said unsaturated hydrocarbon is a chain-conjugated diolefin and/or a monoolefin having 4 or 5 carbon atoms.

5. A process according to Claim 4, in which said chain-conjugated diolefin is butadiene, isoprene or piperylene.

6. A process according to Claim 4, in which said monoolefin is isobutylene.

7. A process according to Claim 1, in which said cyclopentadiene and at least one said unsaturated hydrocarbon are provided in the form of a C5 fraction formed from a cracked crude petroleum or a cracked petroleum fraction and comprising as main component unsaturated hydrocarbon(s) having 5 carbon atoms.

8. A process according to anyone of the preceding Claims, in which said Lewis acid is aluminum trichloride.

9. A process according to any one of the preceding Claims, in which said electron donor is an alcohol or an ether.

10; A process according to Claim 9, in which said alcohol is ethyl alcohol or.butyl alcohol.

11. A process according to Claim 9, in which said ether is diethyl ether, dibutyl ether or tetrahydrofuran.

12. A process according to any one of the preceding Claims, in which said aromatic hydrocarbon is toluene, ethylbenzene, xylene or mesitylene.

13. A process according to any one of the preceding Claims, in which the molar ratio of said Lewis acid to said electron donor to said aromatic hydrocarbon in said catalyst is 1 :0.55.0: 1.010.

14. A process according to any one of the preceding Claims, in which the polymerization is effected in the presence, as solvent, of an aromatic hydrocarbon.

15. A process according to Claim 14, in which the aromatic hydrocarbon employed as solvent is benzene, toluene, ethylbenzene or xylene.

16. A process for producing a cyclopentadiene copolymer in which cyclopentadiene and isoprene are copolymerized in the presence of a catalyst consisting essentially of an aluminium trichloride/diethyl ether or dibutyl ether/xylene complex solution having a molar ratio of 1:1:4.

17. A cyclopentadiene copolymer when produced by a process according to any one of the preceding Claims.

18. A rubber composition comprising a diene rubber and a cyclopentadiene copolymer according to Claim 17 and having a bromine number of from 70 to 240.

19. A composition according to Claim 18, comprising 100 parts by weight of said diene rubber and from 4 to 40 parts by weight of said cyclopentadiene copolymer.

20. A composition according to Claim 19, additionally comprising from 10 to 200 parts by weight of carbon black.

21. A composition according to any one of Claims 18 to 20, in which said diene rubber is natural rubber or a styrene-butadiene copolymer rubber.

22. A composition according to any one of Claims 18 to 21, in which said cyclopentadiene copolymer has a bromine number of from 150 to 240.

23. A product obtained by vulcanizing a rubber composition according to any one of Claims 18 to 22.