JPH0613562B2 - Method for hydrogenating hydroxyl group-containing conjugated diene polymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for hydrogenating a hydroxyl group-containing conjugated diene polymer, and more particularly to a method for hydrogenating a diene polymer having a hydroxyl group at a terminal. In addition, the present invention relates to a method having a high hydrogenation rate and capable of preventing cleavage or desorption of water oxygen.

The polymer product made in this reaction system is particularly suitable for producing polyurethanes by reacting the hydroxyl group-containing polymer with a diisocyanate compound.

(Problems to be Solved by Conventional Techniques and Inventions) Hydroxyl group-containing conjugated diene-based polymers, particularly polyisoprene, polybutadiene or polychloroprene having a hydroxyl group at a molecular end have characteristic properties as raw materials for polyurethane and the like. ing. However, this polyurethane is inferior in weather resistance and heat resistance because of the unsaturated bond existing in the conjugated diene polymer. For the purpose of improving weather resistance and heat resistance, it is common to hydrogenate unsaturated bonds in the presence of a catalyst.

As a hydrogenation catalyst used in such a hydrogenation reaction, a catalyst in which nickel, palladium, ruthenium or rhodium is supported on a carrier such as silica, alumina or diatomaceous earth is known.

However, nickel and palladium catalysts have a low hydrogenation rate of the polymer, while ruthenium and rhodium have a problem of causing a hydroxyl group cleavage reaction of the polymer.

An object of the present invention is to solve the conventional problems described above, and to provide a method capable of hydrogenating a hydroxyl group-containing conjugated diene copolymer at a high hydrogenation rate without cleaving or desorbing the hydroxyl group. .

(Means for Solving Problems) As a hydrogenation method for a hydroxyl group-containing conjugated diene polymer, the present inventors have keenly sought a reaction method having a high hydrogenation rate and not causing hydroxyl group cleavage during hydrogenation. As a result of repeated research,
By using a so-called reduced nickel catalyst, and by using an ether organic solvent or a mixed solvent of an ether organic solvent and a hydrocarbon organic solvent as a solvent during hydrogenation,
The inventors have found that the hydrogenation rate is high, the hydrogenation rate is high, and that the hydroxyl group is not cleaved, and the present invention has been achieved.

That is, the gist of the present invention is to use a reduced nickel catalyst in hydrogenating a hydroxyl group-containing conjugated diene polymer, and use an ether organic solvent as a solvent during hydrogenation, or an ether organic solvent and a hydrocarbon organic solvent. It is to use a mixed solvent of solvents.

The `` hydroxyl group-containing conjugated diene polymer '' to which the hydrogenation method of the present invention is applied is a conjugated diene polymer having a hydroxyl group in the molecule, such as 1,3-butadiene, 1,3-pentadiene, It is a polymer produced by various known methods using monomers such as isoprene, 2,3-dimethylbutadiene and phenylbutadiene as raw materials. Further, not only the above-mentioned homopolymer of conjugated diene-based monomer, but also a copolymer of two or more kinds of conjugated diene-based monomers and a copolymer of conjugated diene-based monomer and vinyl monomer can be used in this reaction. . When copolymerizing two or more conjugated diene-based monomers, the ratio between the respective components is not particularly limited and may be arbitrary. Examples of the vinyl comonomers include styrene, vinyltoluene, alphamethylstyrene,
Examples thereof include vinyl naphthalene, coumarone indene, vinyl pyridine, vinyl furan, acrylonitrile, ethyl acrylate, methyl acrylate, methyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, acrylic acid and methacrylic acid.
Such comonomer is used in an amount of 95% by weight or less, preferably 80% by weight or less, based on the total monomers.

Further, as the number of hydroxyl groups contained in the “hydroxyl group-containing conjugated diene polymer” used here increases, the hydroxyl groups are likely to be cleaved by the hydrogenation reaction, and the hydrogenation catalyst is often deactivated. The preferred hydroxyl group content is 1 in one molecule of the polymer.
It is more than 10 and less than 10.

The number average molecular weight (M _n ) of the hydroxyl group-containing conjugated diene polymer used in the present invention is preferably 500 to 50,000, and more preferably 700 to 30,000. An oligomer having a molecular weight of 500 or less has a drawback that the flexibility of a polyurethane obtained by using the hydrogenated oligomer is insufficient. In addition, since polyurethane having a hydroxyl group-containing conjugated diene polymer hydride having a molecular weight of 50,000 or more has poor compatibility between the hard segment and the soft segment, the hard segment becomes too large and the mechanical strength is lowered. The number average molecular weight described here is a 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, an azobis compound having one or more conjugated diene monomers or a monomer composed of a conjugated diene monomer and a vinyl monomer having a functional group [for example, β, β'-azobis (β-cyano) -n-propanol, δ, δ '-Azobis (δ-cyano) -n-pentanol, etc.] or a peroxide (eg hydrogen peroxide, cyclohexane peroxide, methylcyclohexanone peroxide, etc.) may be used as a catalyst for radical polymerization. Specifically, the case where isoprene is used as a monomer in the experimental method will be described. 300 g of hexane as a solvent, 68 g of isoprene as a monomer, and cyclohexanone peroxide as a catalyst [Chemical Formula Product name Perhexa H 50% product (Nippon Yushi)] 44 g (=
10 mol% / monomer) was charged into one autoclave, heated to 80 ° C. with stirring, and polymerized for 20 hours to give hydroxyl group-containing polyisoprene (yield 65%, M _n
= 5500, OH value 21 mg / g).

The hydroxyl group-containing conjugated diene polymer of the present invention can also be produced by anionically polymerizing the above monomer with an alkali metal such as sodium or lithium as a catalyst, and then adding an alkylene oxide, epichlorohydrin or the like to give a hydroxyl group. A specific example using an isoprene monomer is as follows.
0 ml and 1.3 g of divinylbenzene as a catalyst base were added and kept at -20 ° C, 9.0 g of a 15 wt% solution of n-butyllithium was added dropwise, and the reaction was allowed to proceed for 30 minutes to synthesize a dilithium catalyst. Thereafter, the temperature is raised to −10 ° C., 68 g of isoprene monomer is added dropwise, and anion living reaction is carried out. Polymer yield 9 by 2 hours reaction
It will be 8%. Then, ethylene oxide is added to stop the reaction, and then water is added to obtain polyisoprene having hydroxyl groups added to both terminals (M _n = 7000, OH value 18 mg / g).

In addition to these methods, a method as described in JP-A-57-16003, that is, after adding maleic anhydride to a conjugated diene-based polymer, the formula H ₂ N-- _RA-- OH ( _RA
Is an alkyl group, an aryl group or an aralkyl group) and then heated and dehydrated to form N-hydroxyhydrocarbyl-maleinimide (chemical formula; A hydroxyl group-containing conjugated diene polymer obtained by a method of obtaining a conjugated diene-based polymer to which is added may be used.

When the hydroxyl group-containing conjugated diene polymer obtained by these methods is hydrogenated using reduced nickel as a catalyst and an ether solvent as a solvent, or a mixed solvent consisting of an ether solvent and a hydrocarbon solvent, a hydroxyl group is used. Can be hydrogenated to a high degree and without cutting.

The reduced nickel catalyst used in the present invention is used in the form of being supported on a carrier such as carbon, alumina, silica, diatomaceous earth and the like. Further, a reduced nickel catalyst in which 2 to 30% by weight of nickel is supported on the same carrier by using zirconium, an alkali metal or an alkaline earth metal as a cocatalyst may be used. In any case, the amount of reduced nickel supported on the carrier is 20 to
It may be in the range of 60% by weight, more preferably 30 to 50% by weight.

Examples of the ether-based organic solvent used in the present invention include ethyl ether, n-butyl ether, isopropyl ether, chain ethers such as diisoamyl ether, phenyl ether, anisole, phenetol, phenol ether such as amyl phenyl ether, and tetrahydrofuran. Cyclic ethers such as tetrahydropyran, dioxane, and trioxane are mentioned, and cyclic ethers are particularly preferable. Examples of the hydrocarbon-based organic solvent that can be used as a mixture with the ether-based organic solvent include hexane, heptane, octane, cyclohexane, methylcyclohexane, benzene, toluene and xylene.

The mixing ratio of the ether-based organic solvent and the hydrocarbon-based organic solvent is determined by the type of the organic solvent used and the degree of the target hydrogenation reaction rate, but usually the amount of the ether-based organic solvent in the mixed solvent. Is 1 to 100% by weight, preferably 1
It is 0 to 100% by weight.

The temperature during the hydrogenation reaction in the present invention is usually from room temperature to 2
The temperature can be arbitrarily selected within the range of 00 ° C, but is preferably 80 ° C.
To 180 ° C. If the reaction temperature is lower than room temperature, the hydrogenation rate will be too low, and if it exceeds 200 ° C., the cleavage of hydroxyl groups will be remarkable, such being undesirable.

The hydrogenation rate of the polymer is changed according to the purpose, but the water addition rate is determined by measuring the iodine value of the polymer before and after hydrogenation to obtain a polymer having a predetermined hydrogenation rate.

The amount of reduced nickel to be used can be arbitrarily selected in the range of 0.1 to 100 parts by weight as reduced nickel alone with respect to 100 parts by weight of the hydroxyl group-containing conjugated diene polymer as a raw material, but preferably in the range of 1 to 50 parts by weight. is there.

Also, hydrogen is a flow system at atmospheric pressure or 1 to 300 kg / cm ²
It may be used under moderate pressure, and the hydrogenation reaction may be carried out in a fixed bed,
Any reaction form such as a suspension method can be adopted.

In the method of the present invention, at least 50% of the unsaturated portion of the raw material hydroxyl group-containing conjugated diene polymer, usually 7
0% or more is hydrogenated.

Further, the hydrogenation rate is fast, and the number of hydroxyl groups per molecule hardly changes with respect to that of the raw material. That is, since the hydroxyl group is not cleaved, the curing can be performed very easily when the curing is performed using a conventionally known curing agent such as polyisocyanate in the subsequent steps. Upon curing, fillers such as carbon black, hydrous silica, cream, talc, mica, organic fibers and inorganic fibers can be used for reinforcement or modification.

Hereinafter, the present invention will be described in more detail according to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 Polyhydroxypolyisoprene (M _n = 2) obtained by radical polymerization with hydrogen peroxide in an autoclave having a volume of 1
600, OH number = 45.3mg / g) 100g, reduced nickel 1
0 g (40% nickel loading; diatomaceous earth carrier),
Then, 200 g of tetrahydrofuran was charged as a reaction solvent, the inside of the system was replaced with purified nitrogen gas, and the temperature was raised to 150 ° C. over 30 minutes. When a steady state of 150 ° C. was reached, high-purity hydrogen gas was supplied to the autoclave to carry out the hydrogenation reaction while maintaining the system internal pressure at 50 kg / cm ² . After reacting for a predetermined time, the hydrogenated product was taken out, the catalyst was removed by filtration, and the solvent was further distilled off to obtain a hydrogenated product.

The analytical values of the obtained hydrogenated product are shown in Table 1.

Example 2 Hydroxyl polyisoprene having both terminals (M _n = 1000) obtained by a method in which isoprene was polymerized using an anionic polymerization initiation catalyst composed of a naphthalene / sodium system and ethylene oxide and then water were added to an autoclave having a volume of
0, OH value = 10.5 mg / g) 50 g, reduced nickel 3 g (nickel loading 40%), 1,4-dioxane 200
Grams were charged and the hydrogenation reaction was carried out in the same manner as in Example 1.

The analytical values of the obtained hydrogenated product are shown in Table 1.

Comparative Example 1 A hydrogenated product was obtained by carrying out the hydrogenation reaction in the same manner as in Example 1 except that 200 g of cyclohexane was used as the solvent instead of tetrahydrofuran. The analytical values of the obtained hydrogenated product are shown in Table 1.

From this result, it was revealed that the cyclohexane solvent had a low ultimate addition rate.

Comparative Example 2 A hydrogenated product was obtained in the same manner as in Example 1 except that 10 g of Raney nickel was used as the catalyst instead of reduced nickel. The analysis value of the obtained hydrogenated product is shown in Table-
Shown in 1.

From this result, it was revealed that the Raney nickel catalyst had a low ultimate hydrogenation rate.

Example 3 A hydrogenation reaction was carried out in the same manner as in Example 1 except that a mixed solution containing 70% by weight of ethyl ether and 30% by weight of cyclohexane was used as a solvent. The analytical values of the obtained hydrogenated product are shown in Table 1.

Comparative Example 3 A hydrogenation reaction was carried out in the same manner as in Example 1 except that isopropyl alcohol was used as the solvent used. The analytical values of the obtained hydrogenated product are shown in Table 1.

From this result, it was clarified that the hydrogenation reaction using isopropyl alcohol as a solvent resulted in large cleavage of hydroxyl groups.

Examples 4 to 7 The hydrogenation reaction was carried out under the conditions shown in Table-1 and the results are shown in Table-1.

Comparative Examples 4 to 6 The hydrogenation reaction was performed under the conditions shown in Table-1 and the results are shown in Table-1.

(Effect of the invention) According to the method of the present invention, in the hydrogenation of a hydroxyl group-containing conjugated diene system, by using reduced nickel as a catalyst and an ether solvent as a solvent, or a mixed solution of an ether solvent and a hydrocarbon solvent. It is possible to achieve an extremely high hydrogenation rate with almost no cleavage or elimination of hydroxyl groups. Therefore, the industrial value of the present invention in the field of producing raw materials such as polyurethane and polyester is extremely large.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naotake Minano 36 Towada, Kamisu-cho, Kashima-gun, Ibaraki Prefecture Kuraray Co., Ltd. (56) References JP-A-53-26890 (JP, A)

Claims (6)

[Claims] 1. A method for catalytic hydrogenation of a hydroxyl group-containing conjugated diene polymer, wherein reduced nickel is used as a catalyst, and an ether solvent or a mixed solvent of an ether solvent and a hydrocarbon solvent is used as a solvent. How to characterize. 2. A conjugated diene polymer referred to as a hydroxyl group-containing conjugated diene polymer is a homopolymer of a conjugated diene monomer,
The method according to claim 1, which is a copolymer composed of two or more kinds of conjugated diene-based monomers or a copolymer of a conjugated diene-based monomer and a vinyl monomer. 3. The method according to claim 2, wherein the conjugated diene polymer is polyisoprene. 4. The method according to claim 1, wherein the hydroxyl group-containing conjugated diene polymer has hydroxyl groups at both ends of the molecule. 5. The method according to claim 1, wherein the solvent is a cyclic ether. 6. The method according to claim 1, wherein the cyclic ether is tetrahydrofuran or dioxane.