JPH04255734A - Hydrogenated polymer and composition therefrom - Google Patents

Abstract

PURPOSE:To provide the title butadiene copolymer (and cross-linking rubber composition using the same) excellent in heat and ozone resistance, weatherability, processability, compatibility with other rubbers, etc., made up of two kinds of blocks having each specific structure. CONSTITUTION:The objective copolymer can be obtained by hydrogenating >=75% of the double bonds in the whole butadiene portion of a butadiene polymer 10000-1000000 in weight-average molecular weight and <=10 in molecular weight distribution index, made up of (A) 10-50wt.% of (co)polymer block with 20-35wt.% of the vinyl group in the butadiene portion, made up of (1) 100-50wt.% of butadiene and (2) 0-50wt.% of a vinyl aromatic compound and (B) 90-50wt.% of (co)polymer block with 35-70wt.% of the vinyl group in the butadiene portion, made up of constituents similar to those for the component A, with the amount difference in the vinyl groups for the components A and B being >=10wt.% and said blocks having A-B, A-B-A or B-A-B structure. The other objective rubber composition comprising (a) 100 pts.wt. of a stock rubber containing >=30wt.% of said hydrogenated polymer and (b) 0.1-10wt.% of a cross-linking agent.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogenated butadiene copolymer having excellent heat resistance, weather resistance, ozone resistance, and processability. More specifically, the present invention relates to a hydrogenated butadiene polymer consisting of two types of blocks having a specific structure, and a crosslinking rubber composition using the same.

0002

BACKGROUND OF THE INVENTION Hydrogenated styrene-butadiene copolymers have been known for a long time. For example, Japanese Patent Publication No. 36-3895, Japanese Patent Publication No. 42-89
No. 33 and Japanese Patent Publication No. 42-25304 disclose methods for producing hydrogenated styrene-butadiene copolymers. A method for producing a hydrogenated styrene-butadiene copolymer is described in Japanese Patent Publication No. 45-39274, and a composition with improved strength of an unvulcanized product is described in Japanese Patent Publication No. 46-35497. On the other hand, regarding lubricating oil compositions with little viscosity change,
It is disclosed in Publication No. 203.

On the other hand, a lubricating oil composition with high shear stability using a star-shaped hydrogenated styrene-butadiene copolymer is also disclosed in Japanese Patent Publication No. 50120/1983. In addition, JP-A No. 60-252643 discloses a composition with a polymodal molecular weight distribution and excellent workability and strength, and JP-A No. 62-45883 discloses a diblock type hydrogenated copolymer. , Japanese Patent Publication No. 1-21706
No. 9 discloses a bituminous composition of a diblock polymer consisting of crystalline blocks and amorphous blocks.

[0004] These copolymers are designed to improve heat resistance and crystallinity through hydrogenation, but this alone is sufficient to achieve a sufficient balance of strength, weather resistance, processability, heat resistance, and rubber elasticity at the same time. A satisfactory polymer has not been obtained. Also,
Conventional hydrogenated styrene-butadiene copolymers have poor compatibility when blended with other rubbers, and have insufficient strength and rubber elasticity.

[0005]

[Means for Solving the Problems] The present invention proposes a novel polymer that solves the above-mentioned problems. That is, the present invention provides a block consisting of a butadiene polymer or a butadiene-based random copolymer consisting of 100 to 50% by weight of butadiene and 0 to 50% by weight of a vinyl aromatic compound, and having a vinyl bond content of 20 to 35% in the butadiene moiety. A1
0 to 50% by weight, and 100 to 50% by weight of butadiene.
A block B consists of 90 to 50% by weight of a butadiene polymer or a butadiene random copolymer having a vinyl aromatic compound of 0 to 50% by weight and a vinyl bond amount of 35 to 70% in the butadiene moiety; The difference between the vinyl bonds of the butadiene moieties of block B is at least 1
0%, and the block has an A-B structure or an A-B-A
structure or B-A-B structure, and has a weight average molecular weight (M
w) is 10,000 to 1 million, molecular weight distribution (Mw/Mn) is 1
The present invention provides a hydrogenated polymer in which 75% or more of the double bonds in all butadiene moieties are hydrogenated in a butadiene-based polymer having a molecular weight of 0 or less.

The present invention also includes 100 parts by weight of a raw material rubber containing at least 30% by weight of the above-mentioned hydrogenated polymer, and 0.0% by weight of a crosslinking agent.
A rubber composition of 1 to 10 parts by weight is provided. The block A constituting the polymer before hydrogenation of the hydrogenated polymer of the present invention is one or two aromatic vinyl compounds selected from styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene, etc. A polymer or random copolymer containing 0 to 50% by weight, preferably 0 to 30% by weight of one or more aromatic vinyl compounds, and 100 to 50% by weight, preferably 100 to 70% by weight of 1,3-butadiene. be.

[0007] If the aromatic vinyl compound exceeds 50%, the hydrogenated copolymer loses its rubber elasticity, which is not preferable. The amount of vinyl bonds in the butadiene moiety is 20 to 35%, preferably 25 to 35%. If it is less than 20% by weight, the rubber elasticity decreases, and if it exceeds 35%, the strength decreases, which is not preferable. The content of block A is 10 to 50% by weight,
Preferably it is 10 to 40% by weight. If it exceeds 50% by weight, good rubber properties cannot be obtained, and if it is less than 10%, there is no effect of improving processability.

Block B contains 0 to 50% by weight of one or more aromatic vinyl compounds selected from aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-tert-butylstyrene. , preferably 0 to 30% by weight, 1,3-butadiene 100 to 50% by weight
% by weight, preferably 100-70% by weight of polymer or random copolymer. 50% aromatic vinyl compounds
Exceeding this is not preferable because the hydrogenated copolymer loses its rubber elasticity. The amount of vinyl bonds in the butadiene part is 35 to 70
%, preferably 35 to 60%. If it exceeds 70%, the strength of the hydrogenated polymer decreases, and if it exceeds 35%, it decreases the rubber elasticity of the hydrogenated polymer, which is not preferable.

The difference in the amount of vinyl bonds in the butadiene moiety between block A and block B is at least 10%. If it is less than 10%, the physical property balance between strength and rubber elasticity deteriorates, which is not preferable. When blocks A and B contain an aromatic vinyl compound, they are random copolymers, and the amount of block aromatic vinyl compounds (I.M.Kolthof
f; J. Polym. Sci. 1,429 (19
46). method) is not more than 10% by weight of each polymer block. Block aromatic vinyl compound is 10
If it exceeds % by weight, hardness increases and rubber elasticity is lost, which is not preferable.

On the other hand, the vinyl bonds in the butadiene moiety may exist uniformly within the molecule, or may increase or decrease along the molecular chain. It is necessary that the double bonds in the butadiene moiety of the hydrogenated polymer of the present invention are hydrogenated at least 75%, preferably at least 85%. If it is less than 75%, ozone resistance and heat resistance will be poor, which is not preferable.

The weight average molecular weight (Mw) of the hydrogenated copolymer of the present invention before hydrogenation is 10,000 to 1,000,000, and the molecular weight distribution (M
w/Mn) is 10 or less. Weight average molecular weight is 100
If it is more than 10,000, the processability will be extremely poor, and if it is less than 10,000, the strength of the hydrogenated polymer will be low. When Mw/Mn exceeds 10, surface stickiness due to low molecules becomes severe. The hydrogenated polymer of the present invention before hydrogenation may be produced by any method as long as it has the above-mentioned specific structure. Typical manufacturing methods for obtaining these polymers are shown below.

The polymer before hydrogenation is prepared in an inert solvent such as hexane, cyclohexane, or benzene using an organic lithium such as n-butyllithium or other alkali metal compound as a polymerization catalyst, and if necessary, a cocatalyst. Organic compounds such as alkoxides such as potassium butoxide, organic acid salts such as dodecyl benzene sulfonate, and sodium stearate are used as the components, and if necessary, ether is used as a compound to adjust the amount of vinyl bonds. It can be obtained by copolymerizing the monomer butadiene and optionally styrene in a predetermined ratio using a polar organic compound such as polyether, tertiary amine, polyamine, thioether, hexamethylphosphortriamide, etc. The amount of vinyl bonds can be controlled by the amount of the polar organic compound added and the polymerization temperature.

In addition, in the above polymerization method, various polymerization conditions may be changed, such as adjusting the method of adding monomers, changing the amount of a compound for adjusting the amount of vinyl bonds, the method of addition, and the polymerization temperature during the polymerization reaction. As a result, a copolymer can be obtained in which the styrene content and the amount of vinyl bonds are increased or decreased in the molecular chain as described above. In addition, in polymerization, acetylene, 1
, 2-butadiene, fluorene, primary amines, secondary amines, and the like can also be used.

[0014] Furthermore, the polymer chain having an active end obtained above is coupled with a polyfunctional compound such as silicon tetrachloride, tin tetrachloride, or a polyepoxy compound, or with a branching agent such as divinylbenzene. By adding this to the polymerization system, a branched or radial copolymer can be obtained. That is, block A and block B are combined using a bifunctional or higher coupling agent (X) to form (A)a
-X-(B)b [a+b=2-4, a and b are integers of 1 or more], (A-B)n-X [n=2-4] It is also possible to obtain a polymer having the structure.

The polymerization process for obtaining the above polymers can be a batch process, a continuous process, or a combination thereof. In addition, the copolymer before hydrogenation is
Other polymerization methods other than using lithium catalysts, such as organic compounds such as nickel, cobalt, titanium, etc., and lithium,
A method using a Ziegler catalyst comprising an organic metal component such as magnesium or aluminum or an emulsion polymerization method can also be used.

Any method and conditions for the hydrogenation reaction can be used as long as a polymer having the hydrogenation rate defined in the present invention can be obtained. Examples of such hydrogenation methods include methods using catalysts mainly composed of organometallic compounds of titanium, and methods using catalysts consisting of organic compounds of iron, nickel, and cobalt and organometallic compounds such as alkyl aluminum. A method of using organic complexes of organometallic compounds such as ruthenium and rhodium, palladium, platinum, ruthenium, cobalt,
There is a method of using a catalyst in which a metal such as nickel is supported on a carrier such as carbon, silica, or alumina.

Among various methods, recently developed homogeneous catalysts consisting of an organometallic compound of titanium alone or an organometallic compound of lithium, magnesium, or aluminum (JP-A-59-133203, JP-A-60
-220147) under mild conditions at low pressure and low temperature is industrially preferred. Hydrogenation is carried out in a solvent that is inert to the catalyst and in which the polymer is soluble. Preferred solvents include n-pentane, n-hexane, n-
- aliphatic hydrocarbons such as octane, cyclohexane,
It is a single or a mixture of alicyclic hydrocarbons such as cycloheptane, aromatic hydrocarbons such as benzene and toluene, and ethers such as diethyl ether and tetrahydrofuran.

The hydrogenation reaction is generally carried out by holding the polymer at a predetermined temperature under hydrogen or an inert atmosphere, adding a hydrogenation catalyst with or without stirring, and then introducing hydrogen gas to achieve the predetermined temperature. It is carried out by applying pressure. By inert atmosphere is meant an atmosphere that does not react with any participants in the hydrogenation reaction, such as helium, neon, argon, and the like. Air and oxygen are not preferable because they oxidize the catalyst and cause the catalyst to become deactivated. Further, nitrogen is not preferred because it acts as a catalyst poison during the hydrogenation reaction and reduces the hydrogenation activity. In particular, it is most optimal for the inside of the hydrogenation reactor to have an atmosphere containing only hydrogen gas.

The hydrogenation reaction process for obtaining the hydrogenated polymer can be a batch process, a continuous process, or a combination thereof. Further, when a titanocene diaryl compound is used as a hydrogenation catalyst, it may be added alone to the reaction solution as it is, or may be added as a solution in an inert organic solvent. As the inert organic solvent used when the catalyst is used as a solution, the various solvents mentioned above that do not react with any participating bodies in the hydrogenation reaction can be used. Preferably, it is the same solvent as used in the hydrogenation reaction. In addition, the amount of catalyst added is 0 per 100 g of polymer before hydrogenation.
．． 02-20 mmol.

The most preferable method for obtaining the hydrogenated polymer of the present invention is to carry out solution polymerization of the pre-hydrogenated polymer using an organolithium catalyst and use the obtained polymer solution as it is in the next hydrogenation reaction. It is extremely useful industrially. The hydrogenated polymer of the present invention can be obtained by removing the solvent from the solution obtained above and isolating the polymer.

[0021] The hydrogenated polymer of the present invention takes advantage of its properties and can be used to produce ethylene-propylene rubber, ethylene-propylene-
It can be used in applications where polyene copolymer rubber, butadiene rubber, and styrene-butadiene rubber are currently used. The hydrogenated butadiene copolymer of the present invention can be used alone or blended with natural rubber or other synthetic rubber, and can be mixed, molded, and
After vulcanization, it is used for final use. In this case, in order for the hydrogenated butadiene copolymer of the present invention to exhibit its effects, at least 30% of the raw rubber must be the hydrogenated copolymer of the present invention.

Examples of synthetic rubbers that can be used as a blend include ethylene-propylene rubber, ethylene-propylene-polyene copolymer rubber, butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene, epichlorohydrin rubber, hydrogen Acrylonitrile-butadiene rubber, styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, styrene-isoprene rubber, hydrogenated styrene-isoprene rubber, isoprene rubber,
Examples include chloroprene rubber. Particularly when blended with natural rubber, the hydrogenated butadiene copolymer having a block structure of the present invention brings about favorable effects. A preferred blend ratio is 30% to 90% of the hydrogenated butadiene copolymer and 70% to 10% of the natural rubber.

[0023] Further, in compounding, the compounding agents added to the raw material rubber include reinforcing agents, softeners, fillers, vulcanizing agents, vulcanization accelerators, vulcanization aids, colorants, flame retardants, and lubricants. , foaming agents, plasticizers, processing aids, antioxidants, anti-aging agents, anti-scorch agents, anti-ultraviolet agents, antistatic agents, anti-coloring agents, and other compounding agents, depending on the use of the composition. ,
It is selected and used as appropriate.

[0024] Examples of reinforcing agents to be added to the hydrogenated polymer composition of the present invention include carbon black SAF, SRF furnace black, thermal black such as MT and FT, white carbon, basic calcium carbonate, activated calcium carbonate. Inorganic reinforcing agents such as high styrene resin,
Organic reinforcing agents such as coumaron-indene resin and phenol formaldehyde resin are used, and carbon black and inorganic reinforcing agents are particularly preferred. When using a reinforcing agent, the amount used is 5 to 2 parts per 100 parts by weight of the polymer.
00 parts by weight.

As the filler, calcium carbonate, clay, talc, zeolite, diatomaceous earth, aluminum sulfate, barium sulfate, etc. can be used. Softeners include paraffinic process oil, naphthenic process oil, aromatic process oil, paraffin wax,
Petroleum resin, asphalt, vegetable oil-based softeners, sub-products, etc. are used. Particularly preferred are paraffinic process oils, naphthenic process oils, and aromatic process oils. When a softener is used, the amount used is 1 to 200 parts by weight per 100 parts by weight of the polymer. The amounts of the reinforcing agent and softening agent mentioned above are determined in consideration of the hardness and elastic modulus of the resulting crosslinked rubber composition.

As the crosslinking agent, radical generators such as organic peroxide compounds and azo compounds, as well as oxime compounds, nitroso compounds, and polyamine compounds can be used. As the vulcanizing agent, sulfur, sulfur chloride compounds, organic sulfur compounds, etc. can be used. As the vulcanization accelerator, compounds such as guazine type, aldehyde-amine type, aldehyde-ammonia type, thiazole type, sulfenamide type, thiourea type, thiuram type, dithiocarbamate type, and xanthate type can be used.

As the plasticizer, phthalic acid derivatives, oleic acid derivatives, stearic acid derivatives, phosphoric acid derivatives, etc. can be used. As processing aids, fatty acids such as stearic acid, lauric acid, and palmitic acid, and metal salts thereof can be used. As an antioxidant or anti-aging agent,
Amine derivatives such as diphenylamine and p-phenylenediamine, quinoline derivatives, hydroquinone derivatives, monophenols, diphenols, thiobisphenols, hindered phenols, and phosphorous esters can be used.

[0028] Ultraviolet inhibitor, lubricant, foaming agent, foaming aid,
Known flame retardants, antistatic agents, anticoloring agents, and other rubber compounding chemicals can be used depending on the purpose of use. The hydrogenated polymer composition of the present invention becomes a crosslinked rubber composition through the steps of blending, kneading, molding, and crosslinking using known methods. The crosslinked rubber composition of the present invention can be used as known rubber products, such as tire tubes, engine mounts, bushes, anti-vibration rubbers such as stoppers, window frames, glass steel, sponges, waterproof sheets, and roofings. , electric wires, packing, heater hoses,
It can be used for various purposes such as industrial supplies such as radiator hoses, automobile parts, and construction materials.

[0029]

[Examples] The present invention will be specifically explained below with reference to Examples and Comparative Examples, but these are not intended to limit the scope of the present invention. Example 1 Using a jacketed autoclave with an internal volume of 10 liters and equipped with a stirrer as a reactor, n-hexane was
0ml, n-butyllithium/n-hexane solution (concentration 5% by weight) 9.0ml, tetrahydrofuran (THF)
was introduced in a molar amount 16 times that of lithium, and a 1,3-butadiene/n-hexane solution (butadiene concentration 20% by weight) was
72 ml was added and polymerized at 60°C. Conversion rate is almost 1
After reaching 00%, THF was added in a molar amount 45 times that of lithium, 5510 ml of 1,3-butadiene/n-hexane solution (butadiene concentration 20% by weight) was added, and polymerization was carried out at 60°C. After the conversion rate reaches 100%,
Add methanol in an equimolar amount to living lithium,
Inactivated.

Di-p-tolylbis(1
-cyclopentadienyl) titanium/cyclohexane solution (concentration 1 mmol/liter) 250 ml and n-butyllithium solution (concentration 5 mmol/liter) 50 ml
A solution of 2.0 kg/cm2 of hydrogen at 0°C was added, and the mixture was heated to 90°C at a hydrogen partial pressure of 2.5 kg/cm2.
Allowed to react for minutes. The obtained hydrogenated copolymer contains 2,6- as an antioxidant.
Ditert-butylhydroxytoluene was added at 0.5 parts per polymer and the solvent was removed. Table 1 shows the analytical values of the obtained hydrogenated copolymer. Further, Table 2 shows the vulcanized physical properties of the carbon-blended composition of this hydrogenated copolymer.

[0031]

[Table 1]

[0032]

[Table 2]

Examples 2-6, 11-12, Comparative Examples 1-4
, 7-8 by changing the amount of monomer solution added and the amount of THF added,
A hydrogenated polymer was obtained under the same conditions as in Example 1 except that the abundance ratio of each block and the amount of vinyl bonds were varied. The analytical values of the hydrogenated polymer are shown in Table 1, and the vulcanized physical properties are shown in Table 2.

Example 7 A jacketed autoclave equipped with a stirrer and having an internal volume of 10 liters was used as a reactor, and n-hexane was reacted at 246
0 ml, 1,3-butadiene/n-hexane solution (butadiene concentration 20% by weight), 681 ml, styrene/n-
175 ml of hexane solution (styrene concentration 30% by weight)
After introducing THF in a molar amount 16 times that of lithium, a n-butyllithium/n-hexane solution (concentration 5% by weight) was added to 9.0%
ml was added and polymerized at 60°C. Conversion rate is almost 100
%, THF was added in a molar amount 45 times that of lithium, and 4688 ml of 1,3-butadiene/n-hexane solution (butadiene concentration 20% by weight) and 497 ml of styrene/n-hexane solution were added. Add at the same time, 6
Polymerization was carried out at 0°C. After the conversion rate reached 100%, methanol was added in an equimolar amount to living lithium to deactivate it.

Next, 250 ml of di-p-tolylbis(1-cyclopentadienyl) titanium/cyclohexane solution (concentration 1 mmol/liter) was used as a hydrogenation catalyst.
and 50 ml of n-butyllithium solution (concentration 5 mmol/liter) were added at 0°C under 2.0 kg/cm2 of hydrogen, and a hydrogen partial pressure of 2.5 kg/cm2 was added.
The reaction was carried out for 90 minutes. The obtained hydrogenated copolymer is
0.5 part of 2,6-ditertiarybutylhydroxytoluene was added per polymer as an antioxidant, and the solvent was removed. Table 1 shows the analytical values of the obtained hydrogenated copolymer. Further, Table 2 shows the vulcanized physical properties of the carbon-blended composition of this hydrogenated copolymer.

Examples 8 to 10, Comparative Examples 5 to 6, 9 Hydrogenation was carried out under the same conditions as in Example 7 except that the amount of monomer solution added, the amount of THF added, and the amount of hydrogen supplied during hydrogenation were changed. A copolymer was obtained. The analytical values of the hydrogenated copolymer are shown in Table 1, and the vulcanized physical properties are shown in Table 2.

Example 13 After the synthesis of the copolymer before hydrogenation, a hydrogenated copolymer having an A-B-A block structure was prepared under the same conditions as in Example 1 except that coupling with silicon dichloride was performed. Obtained union. The analytical values of the hydrogenated copolymer are shown in Table 1, and the vulcanized physical properties are shown in Table 2.

Example 14 70 parts by weight of the hydrogenated copolymer obtained in Example 1 and 30 parts by weight of natural rubber were roll blended and the vulcanization properties were measured.

Example 15 40 parts by weight of the hydrogenated copolymer obtained in Example 1 and 60 parts by weight of natural rubber were roll blended and the vulcanization properties were measured.

Comparative Example 10 40 parts by weight of the hydrogenated copolymer obtained in Comparative Example 1 and 60 parts by weight of natural rubber were roll blended and the physical properties of the vulcanization were measured.

The styrene content, the amount of vinyl bonds in the butadiene moiety, the weight average molecular weight (Mw), the molecular weight distribution (Mw/Mn), and the hydrogenation rate of the pre-hydrogenated polymer were measured by the methods shown below. The abundance ratio of each block was determined from the amount of monomer added. Styrene content: The copolymer before hydrogenation is dissolved in chloroform, and UV radiation due to the phenyl group of styrene is
It was measured by absorption at 254 nm.

Amount of vinyl bonds in the butadiene moiety: The copolymer before hydrogenation was dissolved in deuterated chloroform, and FT-NMR (
270MHz, manufactured by JEOL Ltd.), 1H-N
The MR spectrum was measured, and the chemical shift was 4.7 ppm ~
5.2 ppm of protons (=CH2
) and the integrated intensity ratio of protons (=CH-) with a chemical shift of 5.2 ppm to 5.8 ppm.

Weight average molecular weight and molecular weight distribution (Mw/M
n): The polymer before hydrogenation is made into a THF solution, and GPC (Pump: LC-5A manufactured by Shimadzu Corporation, Column: 1 each of polystyrene gel HSG-40, 50, 60, Detector:
The chromatogram was measured using a differential refractometer). The weight-average molecular weight (Mw) and number-average molecular weight (Mn) in terms of polystyrene were calculated by a standard method using a calibration curve showing the relationship between the peak molecular weight and retention volume of standard polystyrene.

Hydrogenation rate: The polymer before hydrogenation and the polymer after hydrogenation were dissolved in deuterated chloroform, and FT-NMR (
270MHz, manufactured by JEOL Ltd.), each NM
The R spectrum was measured, and for the polymer before hydrogenation, a proton (=CH2) due to a vinyl bond with a chemical shift of 4.7 ppm to 5.2 ppm, and a chemical shift of 5.2 p.
Calculate the integrated intensity of protons (=CH-) from pm to 5.8 ppm, while for the polymer after hydrogenation, the methyl protons (-CH-) due to hydrogenated vinyl bonds with chemical shifts from 0.6 ppm to 1.0 ppm. ), a proton due to an unhydrogenated vinyl bond (=CH2) with a chemical shift of 4.7 ppm to 5.2 ppm, and an integral of an unhydrogenated proton (=CH-) with a chemical shift of 5.2 ppm to 5.8 ppm, respectively. Find strength,
The hydrogenation rate was calculated.

Each performance of the vulcanizate shown in Table 2 was measured as follows. (1) Hardness, tensile test: Measured according to JIS-K-6301. (2) Compression set: 12 according to JIS-K-6301
Strain was measured after 70 hours at 5°C. (3) Ozone resistance: 40 according to JIS-K-6301
℃, 20% elongation, ozone concentration 1 ppm, 50
The occurrence of cracks (number, size, and depth of cracks) after 0-hour ozone exposure was observed. (4) Aging resistance: 125 according to JIS-K-6301
Air aging was performed in a Gya aging tester set at ℃.
Changes in tensile strength were measured. (5) Repulsion resilience: Measured using a Lübke type repulsion tester in accordance with JIS-K-6301.

[0046]

Effects of the Invention: By using the hydrogenated polymer having the structure specified by the present invention, a raw material rubber with excellent strength, heat resistance, ozone resistance, and impact resilience, with a particularly well-balanced physical property of compression set and impact resilience. is provided. Further, rubber compositions made from this raw rubber are useful as various industrial products, automobile parts, and construction materials.

Claims (2)

[Claims] Claim 1: A block consisting of a butadiene polymer or a butadiene-based random copolymer consisting of 100 to 50% by weight of butadiene and 0 to 50% by weight of a vinyl aromatic compound, and having a vinyl bond content of 20 to 35% in the butadiene moiety. 10-50% by weight of A and 100-50% by weight of butadiene
and a block B consisting of 90 to 50% by weight of a butadiene polymer or a butadiene random copolymer having a vinyl aromatic compound of 0 to 50% and a vinyl bond content of the butadiene moiety of 35 to 70%, and a block A of 90 to 50% by weight. and the vinyl bond of the butadiene moiety of block B is at least 10%, and the block has an A-B structure or an A-B-
It has an A structure or a B-A-B structure, and has a weight average molecular weight (
A hydrogenated polymer having a molecular weight distribution (Mw/Mn) of 10,000 to 1,000,000 and a molecular weight distribution (Mw/Mn) of 10 or less, characterized in that 75% or more of the double bonds in all butadiene moieties are hydrogenated. Combined. 2. A rubber composition comprising 100 parts by weight of a raw rubber containing at least 30% by weight of the hydrogenated polymer according to claim 1 and 0.1 to 10 parts by weight of a crosslinking agent.