KR101086729B1 - Method for hydrogenationof conjugated diene copolymer - Google Patents

Abstract

The present invention relates to a hydrogenation method of a conjugated diene-based copolymer, and more particularly, lithium hydride (LiH) is formed by spontaneous termination at a predetermined temperature or higher in an alpha-methyl styrene-terminated conjugated diene-based living copolymer. The present invention relates to a hydrogenation method of a conjugated diene copolymer having high hydrogenation rate and hydrogenation reproducibility in a short time without using a reducing agent under an organic titanium catalyst.

Conjugated diene copolymer, hydrogenation method, alphamethyl styrene terminal, lithium hydride, organic titanium catalyst

Description

Method for hydrogenation of conjugated diene copolymers {Method for hydrogenation of conjugated diene copolymer}

The present invention relates to a hydrogenation method of a conjugated diene copolymer.

Polymers of conjugated dienes such as 1,3-butadiene and isoprene or copolymers with vinylaromatic monomers such as styrene copolymerizable with conjugated dienes are widely used as elastomers. These block copolymers of conjugated dienes and vinylaromatic monomers are non-vulcanized thermoplastic elastomers and are used as impact resistant transparent resins or modifiers of polyolefins and polystyrene resins. However, polymers containing olefinically unsaturated double bonds have been applied in a limited range that causes problems in stability such as heat resistance, oxidation resistance and weather resistance due to the reactivity of the double bonds and is not exposed to sunlight or high temperature. In order to overcome this problem, in order to improve the durability and oxidation resistance of the polymer, hydrogen is added to the double bonds in the polymer and partially or completely saturated.

On the other hand, in general, a variety of methods have been reported for the hydrogenation of the polymer having an olefinic double bond, it is largely divided into the following two methods.

The first is a method using a heterogeneous catalyst using metal supported catalysts using noble metal catalysts such as platinum, palladium and rhodium on a support such as carbon, silica or alumina, and the second is Ziegler using nickel and cobalt. It is a method using a catalyst or a homogeneous catalyst of an organometallic compound such as rhodium or titanium.

Hydrogenation reaction using heterogeneous catalyst generally proceeds under high temperature and high pressure conditions, and after the reaction, it is difficult to recover and reuse expensive catalysts by using a filter. There is an expensive disadvantage. On the other hand, when a homogeneous catalyst is used, even in milder conditions, such as low temperature and low pressure, the catalytic activity is high and a high yield of hydrogenation can be expected even with a small amount, and the installation cost is low. There is a disadvantage that it is difficult to separate from the product.

There are several methods for hydrogenating or selectively hydrogenating unsaturated double bonds of conjugated diene polymers. For example, US Pat. Nos. 3,494,942 3,670,054 and 3,700,633 and the like contain polymers containing ethylenically unsaturated double bonds and aromatic and ethylene Described are methods of using suitable catalysts known in the prior art, in particular catalysts containing Group 8, 9, 10 metals or catalyst precursors, to hydrogenate or optionally hydrogenate polymers having sex unsaturated double bonds.

In the process described in this patent, the catalyst is prepared by combining a Group 9, 10 metal, in particular a nickel or cobalt compound with a suitable reducing agent such as aluminum alkyl. In addition, aluminum alkyl is a preferred reducing agent, but it is also known in the prior art that the Group 1, 2 and 13 metals of the Periodic Table of the Elements, in particular lithium, magnesium and aluminum alkyl or hydrides, are effective reducing agents. At this time, the Group 1, Group 2 and Group 13 metals and Group 8, 9 and 10 metals are combined in a range of 0.1: 1 to 20: 1 molar ratio, preferably 1: 1 to 10: 1 molar ratio.

U.S. Patent 4,501,85 discloses that the double bonds in the polymer can be selectively hydrogenated by hydrogenating the conjugated diene polymer in the presence of at least one bis (cyclopentadienyl) titanium compound and at least one hydrocarbon lithium compound. .

In addition, U.S. Patent No. 4,980,421 discloses similar hydrogenation activity by using a combination of an alkoxy lithium compound and a bis (cyclopentadienyl) titanium compound which can be added directly or as an reaction mixture with an organolithium compound and an alcoholic or phenolic compound. Revealed that you can have. It has been mentioned here that the catalyst is active enough to be effective and does not require a deliming step even if the catalyst is used in small amounts so as not to adversely affect the stability of the hydrogenated polymer.

U.S. Patent No. 4,673,714 shows that bis (cyclopentadienyl) titanium compounds preferably hydrogenate double bonds of conjugated dienes, which do not require the use of alkyllithium. A specific example of such a titanium compound is bis (cyclopentadienyl) titanium diaryl compound, which mentions the use of an alkyl lithium compound as an advantage of this catalyst system.

U. S. Patent 5,039, 755 also discloses a process for hydrogenating conjugated diene polymers comprising polymerizing or copolymerizing conjugated diene monomers in organic solvents to produce living polymers. At this time, the resulting living polymer is terminated by the addition of hydrogen. Selective hydrogenation of the double bond in the conjugated diene unit of the terminated polymer is (C ₅ H ₅ ) ₂ TiR ₂ (R = arylalkyl group) carried out in the presence of a catalyst. The hydrogenation step is carried out in the absence of alkyllithium and alkoxylithium compounds. From this patent, US Pat. Nos. 5,132,372 and 5,206,307 refer to the use of alkylbenzoates as promoters to enhance the hydrogenation reaction in the hydrogenation step.

In Korean Patent No. 267,080, at least one conjugated diene is homopolymerized or copolymerized with an organic alkali metal as an initiator to form a living polymer, and the living polymer formed is inactivated, and then lithium hydride and a monocyclopentadienyl titanium compound are combined with hydrogen. And optionally hydrogenated the conjugated diene. In Korean Patent No. 515,452, a lithium hydride having a precisely controlled particle diameter was prepared from a reactor equipped with a high-speed jet nozzle, and used as a main catalyst reducing agent, and a method of hydrogenating a bis (cyclopentadienyl) titanium compound with hydrogen was added. .

However, such techniques, in particular US Pat. Nos. 5,039,755, 5,132,372, and 5,206,307, have had a problem of vigorous stirring to deactivate living polymers with hydrogen gas. In addition, as the scale of the reaction is increased in the preparation of lithium hydride as described in Korean Patent No. 267,080, the end point of the reaction is increased, so that vigorous stirring is required to shorten the reaction time, and the particle size is increased so that the activity control is improved. It is difficult and shows the tendency for the activity as a reducing agent to fall rapidly. Therefore, there is a problem in that a large amount of lithium hydride is required for the stable reaction.

Accordingly, the present inventors have studied to solve the problem in hydrogenating unsaturated double bonds of conjugated diene copolymers using the homogeneous catalyst as described above, and as a result, a constant temperature in the conjugated diene-based living copolymer of The hydrogenation method of a conjugated diene copolymer having high hydrogenation rate and hydrogenation reproducibility within a short time without using a reducing agent under an organic titanium catalyst through a reaction in which lithium hydride (LiH) is produced through spontaneous termination. The present invention has been completed by the development.

Accordingly, an object of the present invention is to provide a new method for hydrogenating conjugated diene copolymers capable of producing hydrogenated polymers with high hydrogenation rate and high reproducibility without exhibiting problems with general homogeneous hydrogenation catalysts.

The present invention

Using a conjugated diene monomer and an aromatic vinyl monomer under a hydrocarbon solvent to produce an living block copolymer of alphamethyl styrene ends using an organolithium compound as an initiator;

Heating and stirring the living block copolymer to produce lithium hydride; And

Selectively hydrogenating only the conjugated diene by adding a bis (cyclopentadienyl) titanium compound represented by the following Chemical Formula 1 and hydrogen as a catalyst to a copolymer of lithium hydride;

There is a feature in the method for producing a hydrogenated conjugated diene polymer comprising;

[Formula 1]

In the above formula, R ₁ and R ₂ are the same as or different from each other, halogen group, C ₁ ~ C ₈ alkyl group, C ₁ ~ C ₈ alkoxy group, C ₆ ~ C ₂₀ arylalkyl, C ₆ ~ C ₂₀ aryloxy group , C ₇ ~ C ₂₀ alkoxyaryl and carbonyl group.

In the present invention, the living end of the conjugated diene-based polymer having alpha methyl styrene as a terminal generates spontaneous termination when heated to 80 ° C. or higher, thereby inactivating the polymer while producing lithium hydride. The lithium hydride formed as described above has a high level of hydrogenation reaction efficiency even at low Li / Ti due to its excellent activity compared to lithium hydride particles which are distributed to the polymer at a molecular level and manufactured and added externally. Can alleviate It is particularly useful industrially because it is an economical and simple ring process that can improve the inefficiency such as high-pressure and high-speed agitation and inefficiencies such as a long time reaction process, which is a problem of a system for producing lithium hydride by terminating polymerization with hydrogen gas. This can be used.

The present invention will be described in detail as follows.

The present invention relates to a hydrogenation method of a conjugated diene copolymer under an organotitanium catalyst without using a reducing agent in a method for hydrogenating a conjugated diene copolymer having alphamethyl styrene as a terminal.

As shown in Scheme 1, the lithium hydride produced by self-termination of the living terminal of alphamethyl styrene without using a separate polymerization terminator and a reducing agent is used for the hydrogenation reaction.

Scheme 1

The hydrogenation method of the conjugated diene copolymer according to the present invention will be described in more detail as follows.

Using a conjugated diene monomer and an aromatic vinyl monomer in an hydrocarbon solvent as an organic lithium compound as an initiator, a living block copolymer terminated with alphamethyl styrene after polymerization is prepared. In addition, the polymerization reaction is such that when the concentration of the polymer is too high, the solution viscosity is rapidly increased, so that the gas and liquid reaction is difficult to efficiently occur so that the concentration of the polymer in the hydrocarbon solvent is 1 to 50% by weight for the reason that the yield of the hydrogenation reaction is lowered. It is preferable to carry out. As the hydrocarbon solvent, aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane and aliphatic ring hydrocarbons such as cyclohexane and cycloheptane may be used, and more preferably, cyclohexane is used.

Lithium hydride is produced by spontaneous termination reaction by heating the copolymer to 80 ° C. or higher (80 to 150 ° C.), and then selectively hydrogenating only a conjugated diene by adding a cyclopentadienyl titanium compound of Formula 1 and hydrogen. .

The hydrogenation reaction is generally carried out under the conditions of reaction temperature 80 ~ 150 ℃, reaction pressure 1 ~ 100 kgf / cm ² , catalyst amount 0.01 ~ 20 mmol / 100 g-polymer, reaction time 15 ~ 1440 minutes, more preferably The reaction temperature is 80 ~ 140 ℃, reaction pressure 5 ~ 20 kgf / cm ² , the amount of catalyst is 0.05 ~ 2 mmol / 100 g-polymer, it is advantageously carried out under the conditions of the reaction time 30 ~ 360 minutes.

Conjugated diene copolymers are generally prepared by anionic polymerization, and the usable conjugated diene monomers are specifically 1,3-butadiene, isoprene, piperylene, phenylbutadiene, 3,4-dimethyl-1,3-hexa Preferred are conjugated diene compounds containing 4 to 12 carbon atoms, such as dienes, 4,5-diethyl-1,3-octadiene, and more preferably 1,3-butadiene and isoprene. . The aromatic vinyl monomer copolymerizable with the conjugated diene monomer is specifically vinyl aryl such as styrene, alpha-methyl styrene, alkoxy-substituted styrene, 2-vinyl pyridine, 4-vinyl pyridine, vinyl naphthalene and vinyl naphthalene substituted with alkyl groups. Compounds may be used, preferably at least one selected from styrene and alphamethyl styrene.

The conjugated diene-based copolymer is prepared by a polymerization method generally used in the art, the present invention is to carry out anionic polymerization using an organolithium compound as an initiator to produce a living copolymer (hydrogenation) using the same The reaction is carried out to prepare a hydrogenated conjugated diene copolymer.

As the catalyst used in the hydrogenation reaction, a bis (cyclopentadienyl) titanium compound generally used in the art may be used. At this time, the catalyst is used alone without a reducing agent.

Such catalysts include, for example, bis (cyclopentadienyl) titanium dihalide compounds, bis (cyclopentadienyl) titanium dialkyl compounds, bis (cyclopentadienyl) titanium diaryl compounds and bis (cyclopentadienyl) It is selected from titanium dialkoxy compounds and can be used alone or in combination.

Unlike styrene, alphamethyl styrene is more stable after lithium hydride is formed because a vinyl group is substituted with a methyl group, and thus, alphamethyl styrene end is more easily produced than lithium styrene end.

In addition, the use of a highly active lithium hydride generated from the living alphamethyl styrene end is less than the amount used when the lithium hydride from the outside has the advantage of preventing the degradation of the transparency and color degradation of the product produced.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

[ Alphamethyl  Styrene-end Living  Block copolymer synthesis]

Comparative Production Example  1: Styrene-butadiene-styrene terminal type Living  Block copolymer

4800 g of cyclohexane, 9.6 g of tetrahydrofuran, and 120 g of styrene monomer were added to a 10-liter autoclave reactor, the temperature was adjusted to 40 ° C., and 13.5 mmol of n-butyllithium was injected to incubate for 30 minutes. Was performed. Next, 560 g of 1,3-butadiene monomer was injected into the reactor and polymerized for 1 hour. Then 120 g of styrene monomer was added and polymerized for 30 minutes, without anion deactivation. The bound styrene content of the copolymer prepared above was 30%, the 1,2-vinyl bond content of the butadiene unit was 38%, and the styrene-butadiene-styrene terminal type living block copolymer having a number average molecular weight of about 62,000 was obtained.

Manufacturing example  1: Styrene-Butadiene- Alphamethyl  Styrene-end Living  Block copolymer

4800 g of cyclohexane, 9.6 g of tetrahydrofuran and 120 g of styrene monomer were added to a 10 L autoclave reactor, the temperature was adjusted to 40 ° C., and 13.5 mmol of n-butyllithium was injected to insulate the reaction for 30 minutes. Was performed. Next, 560 g of 1,3-butadiene monomer was injected into the reactor and polymerized for 1 hour. Then 120 g of alphamethyl styrene monomer was added and polymerized for 30 minutes, without anion deactivation. The styrene-bonded styrene content of the copolymer prepared above is 30%, the 1,2-vinyl bond content of the butadiene unit is 38%, and the number-average molecular weight (Mn) 60,000 is a styrene-butadiene-alphamethyl styrene terminal living block copolymer. Was obtained.

Manufacturing example  2: styrene-butadiene-styrene- Alphamethyl  Styrene-end Living  Block copolymer

4800 g of cyclohexane, 9.6 g of tetrahydrofuran and 120 g of styrene monomer were added to a 10 L autoclave reactor, the temperature was adjusted to 40 ° C., and 13.5 mmol of n-butyllithium was injected to insulate the reaction for 30 minutes. Was performed. Next, 560 g of 1,3-butadiene monomer was injected into the reactor and polymerized for 1 hour. Then 115 g of styrene monomer were added and polymerized for 30 minutes. Then 5 g of alphamethyl styrene was added and polymerized for 10 minutes without anion deactivation. The styrene-linked styrene content of the copolymer prepared above was 30%, the 1,2-vinyl bond content of the butadiene unit was 38%, and the styrene-butadiene-styrene-alphamethyl styrene terminal block copolymer having a number average molecular weight of about 62,000 was Obtained.

Manufacturing example  3: styrene-butadiene- Alphamethyl  Styrene-end Living  Block copolymer

4800 g of cyclohexane, 9.6 g of tetrahydrofuran, and 120 g of styrene monomer were added to a 10-liter autoclave reactor, the temperature was adjusted to 40 ° C., and then 7.6 mmol of n-butyllithium was added to insulate the reaction for 30 minutes. Was performed. Next, 560 g of 1,3-butadiene monomer was injected into the reactor and polymerized for 1 hour. This was followed by addition of 120 g of alphamethyl styrene monomer and polymerization for 30 minutes, without anion deactivation. The styrene-bonded styrene content of the copolymer prepared above was 30%, the 1,2-vinyl bond content of the butadiene unit was 38%, and the styrene-butadiene-alphamethyl styrene terminal type living block copolymer having a number average molecular weight of about 114,000 was obtained. lost

Manufacturing example  4: styrene-butadiene-styrene- Alphamethyl  Styrene-end Living  Block copolymer

4800 g of cyclohexane, 9.6 g of tetrahydrofuran, and 120 g of styrene monomer were added to a 10-liter autoclave reactor, the temperature was adjusted to 40 ° C., and then 7.6 mmol of n-butyllithium was added to insulate the reaction for 30 minutes. Was performed. Next, 560 g of 1,3-butadiene monomer was injected into the reactor and polymerized for 1 hour. Then 115 g of styrene monomer were added and polymerized for 30 minutes. Then 5 g of alphamethyl styrene were added and polymerized for 10 minutes, without anion deactivation. The styrene-bonded styrene content of the copolymer prepared above was 30%, the 1,2-vinyl bond content of the butadiene unit was 38%, and the styrene-butadiene-styrene-alphamethyl styrene-terminated living block copolymer had a number average molecular weight of about 118,000. Was obtained

Comparative Production Example  2: styrene-butadiene-styrene terminal block copolymer

4800 g of cyclohexane, 9.6 g of tetrahydrofuran, and 120 g of styrene monomer were added to a 10-liter autoclave reactor, the temperature was adjusted to 40 ° C., and 13.5 mmol of n-butyllithium was injected to incubate for 30 minutes. Was performed. Next, 560 g of 1,3-butadiene monomer was injected into the reactor and polymerized for 1 hour. Then 120 g of styrene monomer were added and polymerized for 30 minutes. 12.9 mmol of 2,6-di-t-butyl-4-methylphenol was added to deactivate. The styrene-butadiene-styrene terminal block copolymer having a bound styrene content of the copolymer prepared above was 30%, a 1,2-vinyl bond content of 38% butadiene units, and a number average molecular weight (Mn) 62,000. .

Comparative Production Example  3: styrene-butadiene-styrene terminal block copolymer

4800 g of cyclohexane, 9.6 g of tetrahydrofuran, and 120 g of styrene monomer were added to a 10-liter autoclave reactor, the temperature was adjusted to 40 ° C., 13.5 mmol of n-butyllithium was injected, and the adiabatic reaction was performed for 30 minutes. Was performed. Next, 560 g of 1,3-butadiene monomer was injected into the reactor and polymerized for 1 hour. Then 120 g of styrene monomer were added and polymerized for 30 minutes. 6.9 mmol of 2,6-di-t-butyl-4-methylphenol was added to deactivate. A styrene-butadiene-styrene terminal block copolymer having a bound styrene content of the copolymer prepared above was 30%, a 1,2-vinyl bond content of 38% butadiene units, and a number average molecular weight (Mn) of 117,000. .

[ Of lithium hydride (LiH)  synthesis]

Reference Example

In a 5 L autoclave reactor was added 3.5 L n-butyllithium solution or s-butyllithium solution (0.2 M cyclohexane solution) in an inert gas atmosphere and 500 g of tetrahydrofuran was added. The reactor temperature was maintained at room temperature and gas was added while hydrogen was rotated at 500 rpm, and left for 1 hour while maintaining a pressure of 10 kg / cm ² . After one hour, the solution turned into a white suspension. The end point of the reaction is to visually confirm that there is no change in color by taking part of the solution and reacting with the styrene monomer. If unreacted alkyl lithium remains in solution, the polymerization of styrene monomer proceeds to yellow.

[ Conjugated diene system Living  Hydrogenation of Block Copolymer]

Example  1 to 4 and Comparative example  One

2800 g of a solution containing 400 g of the polymer obtained in Comparative Preparation Example 1 and Preparation Examples 1 to 4 was placed in a 5 L autoclave reactor and stirred at 80 ° C. for 10 minutes to produce lithium hydride. Then bis (cyclopentadienyl) titanium dichloride Hydrogenation was carried out for 3 hours by adding 1.6 mmol and pressurizing with 10 kg / cm ² of hydrogen at 400 rpm (rpm). After the reaction was completed, the reactor was cooled to 25 ° C., the pressure was adjusted to atmospheric pressure (760 mmHg), and the reaction solution was added to 200 vol% or more of methanol to precipitate the polymer.

As a result of ¹ H-NMR analysis of the obtained hydrogenated polymer, the hydrogenation rate of butadiene units and the hydrogenation rate of styrene units in the final hydrogenation rate are shown in Table 1 below.

As shown in Table 1, the hydrogenation reaction after stirring for 10 minutes at 80 ℃ resulted in a higher hydrogenation rate of the butadiene units of Preparation Examples 1 to 4 the terminal is living alpha methyl styrene than Comparative Preparation Example 1 of the terminal of the living styrene polymer .

Example  5 to 9

2800 g of a solution containing 400 g of the polymer obtained in Preparation Example 1 was placed in a 5 L autoclave reactor and stirred at 80 ° C. for 10 minutes to produce lithium hydride. Subsequently, the bis (cyclopentadienyl) titanium dichloride input was added in a variable amount as shown in Table 2 below, and pressurized with 10 kg / cm ² of hydrogen at 400 rpm (rpm) to carry out hydrogenation for 3 hours. . After the reaction was completed, the reactor was cooled to 25 ° C., the pressure was adjusted to atmospheric pressure (760 mmHg), and the reaction solution was added to 200 vol% or more of methanol to precipitate the polymer.

As a result of ¹ H-NMR analysis of the obtained hydrogenated polymer, the hydrogenation rate of butadiene units and the hydrogenation rate of styrene units in the final hydrogenation rate are shown in Table 2 below.

Example  10 to 13 and Comparative example  1-4

Examples 10 to 13 put 2800 g of a solution containing 400 g of the polymers obtained in Preparation Examples 1 to 4 into a 5 L autoclave reactor and stirred at 80 ° C. for 10 minutes to produce lithium hydride. Comparative Examples 1 to 4 were prepared by varying the lithium hydride shown in Table 3 to the polymer obtained in Comparative Preparation Examples 2 to 3 and then performing a hydrogenation reaction. In each of Examples 10 to 13 and Comparative Examples 1 to 4, 1.2 mmol of bis (cyclopentadienyl) titanium dichloride was added and hydrogenated at 400 rpm (rpm) with 10 kg / cm ² of hydrogen for 3 hours. The reaction was carried out. After the reaction was completed, the reactor was cooled to 25 ° C., the pressure was adjusted to atmospheric pressure (760 mmHg), and the reaction solution was added to 200 vol% or more of methanol to precipitate the polymer.

As a result of ¹ H-NMR analysis of the obtained hydrogenated polymer, the hydrogenation rate of butadiene units and the hydrogenation rate of styrene units in the final hydrogenation rate are shown in Table 3 below.

As shown in Table 3, when the lithium hydride from the outside when the ratio is about 10 compared to the titanium catalyst it can be seen that the hydrogenation rate is more than 90%.

Claims (9)

Using a conjugated diene monomer and an aromatic vinyl monomer under a hydrocarbon solvent to produce an living block copolymer of alphamethyl styrene ends using an organolithium compound as an initiator; Heating and stirring the living block copolymer to produce lithium hydride; And Selectively hydrogenating only the conjugated diene by adding a bis (cyclopentadienyl) titanium compound represented by the following Chemical Formula 1 and hydrogen as a catalyst to a copolymer of lithium hydride; Hydrogenation method of the conjugated diene-based copolymer comprising a; [Formula 1]

In the above formula, R ₁ and R ₂ are the same as or different from each other, halogen group, C ₁ ~ C ₈ alkyl group, C ₁ ~ C ₈ alkoxy group, C ₆ ~ C ₂₀ arylalkyl, C ₆ ~ C ₂₀ aryloxy group , C ₇ ~ C ₂₀ alkoxyaryl and carbonyl group. The method of claim 1, wherein the temperature for producing the lithium hydride by heating and stirring the living block copolymer is 10 to 150 ℃. The method of claim 1, wherein the conjugated diene monomer is isoprene or 1,3-butadiene. The hydrogenation method according to claim 1, wherein the aromatic vinyl monomer is at least one selected from styrene and alphamethyl styrene. The hydrogenation method according to claim 1, wherein the conjugated diene monomer and the aromatic vinyl monomer are mixed and used in a weight ratio of 1: 9 to 9: 1. The hydrogenation method of claim 1, wherein the organolithium compound is n-butyllithium or sec-butyllithium. According to claim 1, wherein the hydrogenation is carried out under the conditions of reaction temperature 80 ~ 150 ℃, reaction pressure 1 ~ 100 kgf / cm ² , catalyst amount 0.01 ~ 20 mmol / 100 g-polymer, reaction time 15 ~ 1440 minutes Hydrogenation method to use. According to claim 1 or 7, wherein the hydrogenation of the reaction temperature of 80 ~ 140 ℃, reaction pressure 5 ~ 20 kgf / cm ² , the amount of catalyst is 0.05 ~ 2 mmol / 100 g-polymer, reaction time 30 ~ 360 minutes Hydrogenation process characterized in that carried out under. According to claim 1, wherein the hydrogenation method characterized in that the concentration of the polymer in the hydrocarbon solvent to 1 to 50% by weight in the preparation of the copolymer.