JPH09176233A - Method for hydrogenating hydroxy conjugated diene polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hydrogenate a hydroxy conjugated diene polymer at good efficiency while attaining a higher degree of hydrogenation without causing any scission of the intramolecular hydroxyl groups by using a ruthenium catalyst and a cyclic ether solvent. SOLUTION: One hundred (100) pts.wt. hydroxy conjugated diene copolymer having 1-10 hydroxyl groups in the molecule and a number - average molecular weight of 500-800,000 and obtained, for example, by a method comprising radical- polymerizing at least one conjugated diene monomer or a mixture thereof with a vinyl monomer in the presence of a catalyst such as a functional-group- containing azobis compound or a peroxide or anionically polymerizing such a monomer in the presence of a catalyst such as an alkali metal or an alkyllithium compound and adding an alkylene oxide to the reaction mixture to introduce hydroxyl groups into the polymer is hydrogenated at 100-180 deg.C under pressure of atmospheric pressure to 200kg/cm<2> G in the presence of 0.1-50 pts.wt. ruthenium catalyst and 10-200 pts.wt. cyclic ether solvent, the catalyst is removed from the reaction mixture, and the solvent is removed from the obtained mixture by hot drying.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for hydrogenating a hydroxyl group-containing conjugated diene polymer. More specifically, the present invention relates to a method capable of achieving a high hydrogenation rate at a high hydrogenation rate with almost no cleavage of hydroxyl groups in the molecule, and particularly suitable for hydrogenating a conjugated diene polymer having a hydroxyl group at the molecular end.

[0002]

2. Description of the Related Art Hydroxyl group-containing conjugated diene polymers, particularly polyisoprene and polybutadiene having a hydroxyl group at the molecular end, are useful as raw materials for polyurethane and the like. However, such a hydroxyl group-containing conjugated diene polymer is
Since it has an unsaturated bond in the molecule, it has a problem of poor weather resistance and heat resistance. For the purpose of solving such a problem, hydrogenation of an unsaturated bond in the molecule of the hydroxyl group-containing conjugated diene polymer is generally performed.

When hydrogenating a hydroxyl group-containing conjugated diene polymer, for example, a metal such as nickel or palladium is used as a catalyst. However, nickel catalysts generally have a slow hydrogenation rate, and the rate of reduction is particularly remarkable in the latter stage of hydrogenation. On the other hand, when hydrogenation is carried out using a palladium catalyst, there is no problem in terms of hydrogenation rate,
There is a problem that the hydroxyl group at the molecular end of the polymer is likely to be cleaved. As a method capable of solving such problems, a method for hydrogenating a hydroxyl group-containing conjugated diene polymer using a ruthenium catalyst has been proposed (JP-A-50-9).
0694 gazette).

[0004]

DISCLOSURE OF THE INVENTION The present inventors have focused on the technique disclosed in the above publication, and under the reaction conditions described in the publication, carry out a hydrogenation method for a hydroxyl group-containing conjugated diene polymer. Tried. As a result, it is possible to avoid cleavage of hydroxyl groups in the molecule, but the rate of hydrogenation is not sufficiently high, and it is necessary to perform hydrogenation for a relatively long time in order to achieve a high hydrogenation rate. Admitted that. Thus, the present invention provides a method for efficiently hydrogenating a hydroxyl group-containing conjugated diene polymer, which can achieve a high hydrogenation rate at a higher hydrogenation rate without causing cleavage of hydroxyl groups in the molecule. The challenge is to provide.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that when a hydrogen-containing conjugated diene polymer containing a hydroxyl group is hydrogenated using a ruthenium catalyst, a specific solvent is used. It was found that the use of the above-mentioned compound makes it possible to achieve a high hydrogenation rate in a short reaction time with almost no cleavage of hydroxyl groups in the molecule, and has completed the present invention. That is, the present invention is a method for hydrogenating a conjugated diene polymer having a hydroxyl group, which comprises using a ruthenium catalyst as a catalyst and a cyclic ether solvent as a solvent.

The "hydroxyl group-containing conjugated diene polymer" to be hydrogenated in the present invention means a conjugated diene polymer having a hydroxyl group in the molecule, for example, 1,3-butadiene. , 1,3-pentadiene, isoprene, 2,3-dimethylbutadiene, phenylbutadiene, and the like are referred to as a polymer having a hydroxyl group in the molecule produced by various known methods using a conjugated diene monomer as a raw material. Further, not only a homopolymer of the above conjugated diene monomer, but also a copolymer composed of two or more kinds of conjugated diene monomers and a copolymer of a conjugated diene monomer and a vinyl monomer can be used as the above-mentioned "hydroxyl group-containing conjugated diene polymer". ”. Here, there is no particular limitation on the ratio of the respective constituent components in the copolymer composed of two or more kinds of conjugated diene monomers and the copolymer of the conjugated diene monomer and the vinyl monomer. The form of these copolymers may be any of block, random, and taper forms.

Examples of the vinyl monomer include, for example,
Styrene, vinyltoluene, α-methylstyrene, vinylnaphthalene, coumaroneindene, vinylpyridine, vinylfuran, acrylonitrile, ethyl acrylate,
Examples thereof include methyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, acrylic acid and methacrylic acid. The vinyl monomer is used in an amount of 95% by weight or less, preferably 80% by weight or less, based on the total monomers.

As the number of hydroxyl groups contained in the hydroxyl group-containing conjugated diene polymer increases, cleavage of the hydroxyl groups in the molecule tends to occur during hydrogenation. Therefore, the number of hydroxyl groups contained in the hydroxyl group-containing conjugated diene polymer is preferably 10 or less per molecule of the polymer.

The number average molecular weight (Mn) of the hydroxyl group-containing conjugated diene polymer is preferably 500 to 800,000, more preferably 700 to 400,000. The number average molecular weight of the hydroxyl group-containing conjugated diene polymer referred to herein is the polystyrene equivalent number average molecular weight measured by gel permeation chromatography (GPC).

The hydroxyl group-containing conjugated diene polymer used in the present invention can be obtained by various methods. For example, one or more kinds of conjugated diene monomers, or a monomer mixture containing a conjugated diene monomer and a vinyl monomer is added to β, β′-azobis (β-cyano) -n-propanol, δ, δ′-
Azobis compounds having a functional group such as azobis (δ-cyano) -n-pentanol; or obtained by radical polymerization using hydrogen peroxide, cyclohexane peroxide, peroxides such as methylcyclohexanone peroxide as a catalyst. it can.

Further, the hydroxyl group-containing conjugated diene polymer is
At least one conjugated diene monomer or a monomer mixture comprising a conjugated diene monomer and a vinyl monomer may be used as an alkali metal such as sodium or lithium; an alkyllithium compound such as butyllithium; or 1,3-phenylenebis (3-methyl-1). It can also be obtained by anionic polymerization using a dilithium compound such as -phenylpentylidene) dilithium as a catalyst, and then adding alkylene oxide, epichlorohydrin or the like to introduce a hydroxyl group.

Further, as the hydroxyl group-containing conjugated diene polymer, in addition to these methods, JP-A-57-16003 is used.
N obtained by the method described in the publication
It is also possible to use a conjugated diene-based polymer containing a -hydroxyhydrocarbyl maleimide group in the molecule.

In the present invention, the above hydroxyl group-conjugated diene polymer is hydrogenated using a ruthenium catalyst as a catalyst and a cyclic ether solvent as a solvent.

As the ruthenium catalyst, known ones can be used without particular limitation. For example, those supported on a carrier such as carbon, alumina, silica, diatomaceous earth may be used, or ruthenium may be used. A ruthenium metal such as black may be used. When a ruthenium catalyst supported on a carrier is used, the amount of ruthenium supported is usually 0.05 to 100 with respect to 100 parts by weight of the carrier.
Parts by weight, preferably 0.1 to 50 parts by weight.

The amount of the ruthenium catalyst used is preferably 0.1 to 50 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the hydroxyl group-containing conjugated diene polymer.

Examples of the cyclic ether solvent used in the present invention include 1,4-dioxane, 1,3-dioxolane, trioxane and tetrahydrofuran.

In the present invention, the above cyclic ether type solvent may be mixed with a hydrocarbon type solvent for use, if desired. Examples of such a hydrocarbon solvent include hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene, xylene and the like.
The amount of the hydrocarbon-based solvent used is preferably within 100 times the weight of the cyclic ether-based solvent.

The amount of the solvent used varies depending on the molecular weight of the hydroxyl group-containing conjugated diene polymer to be subjected to hydrogenation.
10 per 100 parts by weight of the hydroxyl group-containing conjugated diene polymer
Is in the range of up to 200 parts by weight. It should be noted that the higher the molecular weight of the hydroxyl group-containing conjugated diene polymer, the better the tendency tends to be to obtain a larger amount of the solvent.

The hydrogenation is usually carried out at a temperature in the range of room temperature to 200 ° C., preferably at a temperature in the range of 100 to 180 ° C.

The hydrogenation may be carried out either under normal pressure or under increased pressure, but it is preferably carried out under a pressure in the range of normal pressure to 200 kg / cm ² G, and normal pressure to 100 kg.
More preferably, it is carried out under a pressure in the range of / cm ² G. The hydrogenation can be carried out in a stirred reactor with the catalyst suspended in the liquid phase, or in a fixed bed reactor packed with a supported catalyst. In addition, the method may be either continuous or batch.

The hydrogenated hydroxyl group-containing conjugated diene polymer can be obtained by treating the reaction mixture after completion of the hydrogenation reaction according to a conventional method. That is,
The hydrogenated hydroxyl group-containing conjugated diene polymer can be obtained by removing the catalyst from the reaction mixture by means such as filtration and then removing the solvent by heating and drying, steam stripping and the like.

According to the hydrogenation method of the present invention, at least 50% of the unsaturated portion of the hydroxyl group-containing conjugated diene polymer, which is the starting material, can be obtained even if the reaction time is as short as 3 hours.
Usually 70% or more can be hydrogenated. Further, according to the hydrogenation method according to the present invention, since hydrogenation can be carried out with almost no cleavage of hydroxyl groups in the molecule, when the obtained hydride is reacted with polyisocyanate or the like, the reaction is smoothly performed. Can be carried out.

[0023]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

EXAMPLE 1 Polyhydroxypolyisoprene obtained by radical polymerization using hydrogen peroxide in a 1 liter capacity autoclave [number average molecular weight (Mn): 2,600, contained in one molecule of polymer] Number of hydroxyl groups: 2.25] 100
g, carbon-supported ruthenium (Ru supported amount: 5%, manufactured by NE Chemcat) 0.5 g, and 1,4-dioxane 100 g as a solvent were charged, and the system was replaced with nitrogen gas. The internal temperature was raised to 150 ° C over a period of minutes. Hydrogen gas was supplied into the autoclave at the time when the steady state of 150 ° C was reached, and the system internal pressure was 50 kg / c.
Hydrogenation was carried out for 5 hours while maintaining m ² G and the reaction temperature at 150 ° C. After the reaction was completed, the reaction mixture was filtered to remove the catalyst, and then the solvent was distilled off to remove the hydrogenation product.
g was obtained. Table 1 shows the analytical values of the obtained hydrogenated products.

Example 2 Instead of 100 g of 1,4-dioxane as a solvent,
90 g of a hydrogenated product was obtained in the same manner as in Example 1 except that 100 g of trioxane was used. The analytical values of the obtained hydrogenated products are also shown in Table 1.

Example 3 Instead of 100 g of 1,4-dioxane as a solvent,
90 g of a hydrogenated product was obtained in the same manner as in Example 1 except that 100 g of tetrahydrofuran was used. The analytical values of the obtained hydrogenated products are also shown in Table 1.

Comparative Example 1 Instead of 100 g of 1,4-dioxane as a solvent,
Example 1 except that 100 g of cyclohexane was used
90 g of a hydrogenated product was obtained in the same manner as in. The analytical values of the obtained hydrogenated products are also shown in Table 1.

[0028]

[Table 1]

[0029]

EFFECT OF THE INVENTION According to the present invention, hydrogenation of a hydroxyl group-containing conjugated diene polymer capable of achieving an extremely high hydrogenation rate at a high hydrogenation rate with almost no cleavage of the hydroxyl group in the molecule. A method is provided.

Claims (1)

[Claims] 1. A method for hydrogenating a hydroxyl group-containing conjugated diene polymer, which comprises using a ruthenium catalyst as a catalyst and a cyclic ether solvent as a solvent. Hydrogenation method.