JPH1180251A - Hydrogenation method of polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effect an industrially advantageous hydrogenation with reduced amount of a catalyst by hydrogenating a polymer having an olefinically unsaturated double bond in the presence of a catalyst comprising an organometallic compound of a group VIII metal and an organoaluminum compound at a specific ratio. SOLUTION: An organoaluminum compound is an alkyl aluminum compound represented by the formula: (R)3 Al (wherein R is an alkyl having 6 or more carbon atoms) having the molar number ratio of aluminum/the group VIII metal of 0.5/1-10/1. Examples of a polymer having an olefinically unsaturated double bond include a homopolymer of a conjugated diene compound, a copolymer of two or more conjugated diene compounds, a copolymer of a conjugated diene compound and an olefinic monomer, a norbornene-based polymer and a cyclopentene-based polymer, which are especially effective when employed in preparing a tri-substituted polymer having an olefinically unsaturated double bond.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for hydrogenating a polymer containing an olefinically unsaturated double bond (hereinafter referred to as an unsaturated bond-containing polymer).

[0002]

2. Description of the Related Art Unsaturated bond-containing polymers typified by conjugated diene polymers are used as base polymers such as asphalt modifiers, plastic modifiers and adhesives, and as substitute materials for vulcanized rubber. Is widely used as a base polymer for compounds and as a modifier for vulcanized rubber. Olefinic unsaturated double bonds in these unsaturated bond-containing polymers are effectively used in vulcanization treatments and the like, but on the other hand, due to the presence of such olefinic unsaturated double bonds, heavy The heat resistance and weather resistance of the coalescence itself are impaired. Therefore, in applications requiring heat resistance and weather resistance, the olefin unsaturated double bond in the molecule is hydrogenated to improve heat resistance and weather resistance before use.

[0003] As a method for hydrogenating an olefinically unsaturated double bond in an unsaturated bond-containing polymer, a Raney nickel catalyst or a metal such as nickel, platinum, palladium, ruthenium or rhodium can be used, such as carbon, silica, alumina and diatomaceous earth. Hydrogenation using a solid catalyst supported on a carrier, a bis (cyclopentadienyl) metal compound comprising a transition metal such as titanium, zirconium or hafnium and lithium, sodium, potassium, aluminum,
Hydrogenation using a homogeneous catalyst comprising an organometallic compound such as zinc or magnesium; an organometallic compound comprising a Group VIII metal such as nickel or cobalt and an organoaluminum such as triethylaluminum or triisobutylaluminum A method of hydrogenation using a homogeneous catalyst comprising a compound and the like are known.

[0004]

However, the solid catalyst used in the above method generally has a lower activity than a homogeneous catalyst, so that the amount of the catalyst used increases.
When hydrogenation of a high molecular weight polymer is carried out, filtration for removing the catalyst after the completion of hydrogenation requires a considerable time since the viscosity of the polymer solution is relatively high. For this reason, solid catalysts are actually used for hydrogenation of low molecular weight polymers, but are not suitable for hydrogenation of high molecular weight polymers.

It is said that the catalyst used in the above method does not need to be removed because the catalyst activity is sufficiently high and the amount used is small, but the obtained hydrogenated polymer is colored. There are problems such as doing. Then, the present inventors performed hydrogenation of the unsaturated bond-containing polymer using the above-mentioned catalyst, and as a result, although the catalytic activity for the olefinically unsaturated double bond up to 2 substitution was high,
The catalytic activity for the trisubstituted olefinically unsaturated double bond was very low, indicating that the hydrogenation reaction hardly proceeded.

On the other hand, the catalyst used in the above-mentioned method has a sufficient catalytic activity not only for olefinically unsaturated double bonds up to disubstitution but also for tertiary olefinically unsaturated double bonds. I have. However, the catalyst used in the above method requires a relatively large amount of the catalyst as compared with the catalyst used in the above method, which leads to an increase in the production cost and remains in the obtained hydrogenated polymer. The amount of the catalyst to be used is large, and may cause a decrease in heat resistance and weather resistance of the hydrogenated polymer. The present invention has been made in view of the above problems, and is applicable to an unsaturated bond-containing polymer having a trisubstituted olefinically unsaturated double bond. An object of the present invention is to provide an industrially advantageous method for hydrogenating an unsaturated bond-containing polymer, which requires a small amount.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have focused on the catalyst used in the above-mentioned method, and as a result, have found that the alkyl of the organoaluminum compound constituting the catalyst has been developed. The inventors have found that the structure of the group is an important factor influencing the catalytic activity, and as a result of further study, have completed the present invention.

That is, the present invention provides a method for hydrogenating an unsaturated bond-containing polymer using a catalyst comprising an organometallic compound comprising a Group VIII metal and an organoaluminum compound, wherein the organoaluminum compound is An alkylaluminum compound represented by the following formula (1) (R) ₃ Al (1) (wherein R represents an alkyl group having 6 or more carbon atoms), and the number of moles of aluminum in the organoaluminum compound is The second
A method for hydrogenating an unsaturated bond-containing polymer, wherein the ratio of the number of moles of the Group VIII metal is from 0.5 / 1 to 10/1.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the present invention, the unsaturated bond-containing polymer to be hydrogenated means a polymer containing an olefinic carbon-carbon double bond in the molecular chain or in a side chain of the polymer.
Specific examples of such a polymer include a homopolymer of a conjugated diene compound, a copolymer of two or more conjugated diene compounds, and a copolymer of at least one conjugated diene compound and at least one olefinic monomer. , Norbornene-based polymer,
Examples thereof include cyclopentene polymers, and the hydrogenation method of the present invention is particularly effective when applied to a polymer containing three or more olefinically unsaturated double bonds. Here, the ratio of each component in the copolymer of two or more conjugated diene compounds and the copolymer of the conjugated diene compound and the olefinic monomer is not particularly limited.
The molecular structure of these copolymers may be any of block, random, and tapered. Also,
In the unsaturated bond-containing polymer, the microstructure of the portion derived from the conjugated diene compound is not particularly limited.

Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-
Methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene and the like, among which 1,3-butadiene, Isoprene is preferred. Among such conjugated diene compounds, those which give an olefinically unsaturated double bond having three or more substitutions include isoprene, 2,3-dimethyl-1,3-butadiene, 2-
Methyl-1,3-pentadiene, 4,5-diethyl-
Examples thereof include 1,3-octadiene and 3-butyl-1,3-octadiene.

The olefinic monomer is not particularly limited as long as it can be copolymerized with a conjugated diene compound. Examples thereof include styrene, α-methylstyrene, p-methylstyrene and t-butyl. Styrene, 1-vinylnaphthalene, 3-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene, cumarone, indene, vinylpyridine , Vinylfuran, acrylonitrile, ethyl acrylate, methyl acrylate, methyl methacrylate, t-butyl methacrylate, hydroxyethyl methacrylate, acrylic acid, methacrylic acid, etc., of which styrene is particularly preferred.

The number average molecular weight (Mn) of the unsaturated bond-containing polymer used in the present invention is not particularly limited, but is usually from 500 to 2,000,000. Here, the number average molecular weight is a number average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

The unsaturated bond-containing polymer used in the present invention has a hydroxyl group at the molecular terminal or in the molecular chain.
It may have a substituent such as a carboxyl group, a carbonyl group, an ester group or an amino group.

Further, the form of the unsaturated bond-containing polymer used in the present invention is not particularly limited, and may be any of linear, branched or star. The method for producing the unsaturated bond-containing polymer used in the present invention is not particularly limited, and any known method may be used.

Next, the hydrogenation catalyst used in the present invention will be described. In the present invention, a catalyst comprising an organometallic compound comprising a Group VIII metal and an organoaluminum compound represented by the above formula (1) is used.
Group VIII metals include, for example, nickel, cobalt,
Iron, copper, etc. are used. As the organometallic compound comprising a Group VIII metal, various forms such as a carboxylate and a complex salt with acetylacetone can be used. Examples of the carboxylate include a Group VIII metal and naphthenic acid, 2-ethylhexanoic acid, octanoic acid,
Examples thereof include salts with methyloctanoic acid, nonanoic acid, linoleic acid, oleic acid, myristic acid, palmitic acid, stearic acid, benzoic acid, t-butylbenzoic acid, and the like.
Examples of the complex salt with acetylacetone include acetylacetone nickel complex, acetylacetone cobalt complex, and acetylacetone iron complex. Among these, nickel 2-ethylhexanoate, nickel acetylacetone complex, cobalt 2-ethylhexanoate, and acetylacetone cobalt complex are preferred. Organometallic compounds consisting of Group VIII metals may be used alone,
Two or more kinds may be used in combination.

In the above formula (1) representing the organoaluminum compound used in the present invention, examples of the alkyl group having 6 or more carbon atoms represented by R include, for example, n-
Hexyl group, n-heptyl group, 2-ethylhexyl group,
Examples include an n-octyl group, an n-nonyl group, an n-decyl group, an n-hexadecyl group, and an n-eicosyl group.
Usually, the number of carbon atoms is 20 or less, and among them, n-hexyl group and n-octyl group are preferable. Note that 3 in equation (1)
R generally represent the same thing, but may represent different things. The organoaluminum compound represented by the formula (1) may be used alone or in combination of two or more.

The composition of the hydrogenation catalyst used in the present invention is determined by the number of moles of aluminum in the organoaluminum compound represented by the formula (1) and the number of moles of the group VIII metal in the organometallic compound comprising the group VIII metal. (Hereinafter abbreviated as Al / M ratio) in a ratio of 0.5 / 1 to
It needs to be 10/1. When the proportion of the organoaluminum compound represented by the formula (1) is less than the above range, the catalytic activity decreases, and severe conditions such as high temperature and high pressure are required for hydrogenation. On the other hand, when the proportion of the organoaluminum compound represented by the formula (1) is more than the above range, a side reaction such as breaking of the molecular chain of the unsaturated bond-containing polymer may occur during hydrogenation, Not preferred. The composition of the hydrogenation catalyst preferably has an Al / M ratio of 2/1 to 6/1.

The amount of the hydrogenation catalyst used in the present invention varies depending on the reaction conditions such as the reaction temperature and the hydrogen pressure, but it depends on the number of moles of the olefinic carbon-carbon double bond in the unsaturated bond-containing polymer. On the other hand, the proportion of the organometallic compound comprising a Group VIII metal is 0.005 mol% or more, preferably 0.05 to 1 mol%. The hydrogenation catalyst used in the present invention can be prepared using a conventionally known method. Specific examples include a method of previously mixing a predetermined amount of an organoaluminum compound represented by the formula (1) and an organometallic compound comprising a Group VIII metal in a solvent such as cyclohexane, Formula (1) is added to the hydrogenation reaction vessel charged with coalescence.
And a method of supplying and mixing the organoaluminum compound and the organometallic compound comprising a Group VIII metal, respectively. The preparation of the hydrogenation catalyst used in the present invention is preferably performed, for example, under an inert gas such as nitrogen, helium, or argon, or a hydrogen atmosphere.

The hydrogenation reaction according to the present invention is usually carried out in the presence of a solvent. Here, as the solvent, those that are inert to the hydrogenation catalyst and do not adversely affect the hydrogenation reaction are used, for example, saturated aliphatic hydrocarbons such as pentane, hexane, heptane, and octane. Saturated alicyclic hydrocarbons such as cyclopentane, cyclohexane and methylcyclohexane; and aromatic hydrocarbons such as benzene and toluene. These solvents optionally contain ethers such as diethyl ether, dibutyl ether, tetrahydrofuran (THF), 1,4-dioxane, and 1,3-dioxolan; and glycol ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether. Is also good.

Although the amount of the solvent used is not particularly limited, the concentration of the unsaturated bond-containing polymer is usually 1 to 8 from the viewpoints of the reaction rate of hydrogenation, the volumetric efficiency of the reaction and the operability during the reaction.
The amount is in the range of 0% by weight, preferably 5 to 50% by weight. The hydrogen pressure in the hydrogenation reaction varies depending on the catalyst to be used, the desired hydrogenation rate, and the like.
It was 100 kg / cm ^2, preferably 4~50kg / cm ^2. The reaction temperature in the hydrogenation reaction is usually 0 to 15
0 ° C., preferably 50 to 130 ° C. Also,
The reaction time depends on the type and amount of the catalyst used, the reaction temperature,
It usually varies from 1 minute to 5 minutes, depending on the reaction conditions such as hydrogen pressure.
0 hours.

The hydrogenation reaction according to the present invention can be carried out in a reaction vessel such as a stirring system or a bubble column. Further, it can be carried out by any of a continuous system and a batch system.

The unsaturated bond-containing polymer hydrogenated by the hydrogenation method described above (hereinafter, abbreviated as a hydrogenated polymer) is usually brought into contact with an aqueous solution of an organic acid or an inorganic acid. Thus, after removing the catalyst from the reaction solution, it can be obtained by treating according to a known method. As a method for treating the polymer solution, for example, a method in which the polymer solution is put into hot water together with steam, the solvent is removed by steam distillation, and the hydrogenated polymer is recovered in a crumb form (steam stripping method);
A method in which the polymer solution is directly heated to distill off the solvent; or a method in which the polymer solution is poured into a poor solvent for the hydrogenated polymer to precipitate the hydrogenated polymer.

[0023]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples.
In the following Reference Examples and Examples, the number average molecular weight of the polymer and the vinyl bond content (1,2-bond and 3,4-bond
The total amount of bonds), the hydrogenation ratio and the molecular weight distribution were measured by the following methods. Number average molecular weight It was determined as the number average molecular weight in terms of polystyrene by GPC measurement. The vinyl bond content was calculated from the ¹ H-NMR spectrum. Hydrogenation rate The iodine value of the polymer before and after hydrogenation was measured, and the hydrogenation rate was calculated from the measured value. Change in molecular weight distribution GPC measurement was performed on each of the polymers before and after hydrogenation, and the results were compared to evaluate the presence or absence of a change in the molecular weight distribution. The expansion of the molecular weight distribution means that the molecular chain of the polymer was cut by hydrogenation.

Reference Example 1 A pressure-resistant reaction vessel purged with dry nitrogen was charged with cyclohexane as a solvent and sec-butyllithium as a polymerization initiator, and then was added with isoprene, followed by polymerization at 50 ° C. Polyisoprene having a molecular bond content of 40,000 and a vinyl bond content of 9 mol% was obtained (hereinafter abbreviated as polymer 1).

REFERENCE EXAMPLE 2 Cyclohexane as a solvent and sec-butyllithium as a polymerization initiator were charged into a pressure-resistant reaction vessel purged with dry nitrogen, and then THF was charged. Then, isoprene and styrene were added in this order, and 50 ° C. The polymerization was carried out. By this polymerization reaction, a random copolymer consisting of styrene and isoprene having a styrene content of 20% by weight, a number average molecular weight of 38,000 and a vinyl bond content of 40 mol% was obtained (hereinafter referred to as polymer 2). ).

Reference Example 3 A pressure-resistant reaction vessel replaced with dry nitrogen was charged with cyclohexane as a solvent and sec-butyllithium as a polymerization initiator, and then styrene and isoprene were added in this order to carry out polymerization at 50 ° C. . The addition of isoprene
It was performed after the polymerization of styrene was completed. As a result of such polymerization reaction, the number average molecular weight of the polymer block composed of styrene is 4,000, the number average molecular weight of the polymer block composed of isoprene is 36,000, the vinyl bond content is 9 mol%, and the styrene content is 10% by weight. % Of a diblock-type styrene-isoprene block copolymer (hereinafter, abbreviated as polymer 3).

Example 1 Cyclohexane and nickel acetylacetone were charged into a dry nitrogen-purged reaction vessel, and then trinormal octyl aluminum (hereinafter referred to as TNOAL
) Was added with stirring to prepare a cyclohexane solution of the hydrogenation catalyst. In this hydrogenation catalyst, the Al / M ratio was 3/1. Using the cyclohexane solution of the hydrogenation catalyst obtained above, hydrogenation of the polymer 1 in cyclohexane is performed so that the concentration of the polymer 1 is 20% by weight, the reaction temperature is 90 ° C., and the hydrogen pressure is 10 kg / cm ^2. It was carried out under conditions and stirring. The amount of the hydrogenation catalyst used was such that the ratio of nickel acetylacetone to the number of moles of the olefinically unsaturated double bond in Polymer 1 was 0.15 mol%. Table 1 shows the changes in the hydrogenation rate and the molecular weight distribution 4 hours after the start of the reaction.

Example 2 In Example 1, Polymer 2 was used in place of Polymer 1, and the amount of the hydrogenation catalyst used was changed based on the number of moles of the olefinically unsaturated double bond in Polymer 2 by acetylacetone. The same operation as in Example 1 was performed, except that the ratio of nickel was changed to 0.3 mol%, to hydrogenate the polymer. Table 1 shows the changes in the hydrogenation rate and the molecular weight distribution 4 hours after the start of the reaction.

Example 3 Hydrogenation of a polymer was carried out in the same manner as in Example 1 except that Polymer 3 was used instead of Polymer 1. Table 1 shows the changes in the hydrogenation rate and the molecular weight distribution 4 hours after the start of the reaction.

Example 4 A hydrogenation catalyst was prepared in the same manner as in Example 1 except that trinormal hexyl aluminum (hereinafter referred to as TNHAL) was used in the same mole number in place of TNOAL. Prepare a cyclohexane solution,
Thereafter, the same operation as in Example 1 was performed to hydrogenate the polymer 1. Table 1 shows the changes in the hydrogenation rate and the molecular weight distribution 4 hours after the start of the reaction.

Comparative Example 1 A hydrogenation catalyst cyclohexane was prepared in the same manner as in Example 1 except that triethylaluminum (hereinafter abbreviated as TEA) was used in the same mole number in place of TNOAL. A solution was prepared, and the same operation as in Example 1 was performed to hydrogenate the polymer 1. Table 1 shows the changes in the hydrogenation rate and the molecular weight distribution 4 hours after the start of the reaction.

Comparative Examples 2 and 3 In Example 1, nickel acetylacetone and TNOA
A cyclohexane solution of the hydrogenation catalyst was prepared in the same manner as in Example 1 except that the ratio of L and the amount of the hydrogenation catalyst used were changed as shown in Table 1, and the same operation as in Example 1 was performed. Hydrogenation of polymer 1 was performed. Table 1 shows changes in the hydrogenation rate and molecular weight distribution 4 hours after the start of the reaction.
Shown in

Comparative Example 4 In Comparative Example 1, Polymer 2 was used in place of Polymer 1,
The same as Comparative Example 1 except that the amount of the hydrogenation catalyst was changed such that the ratio of nickel acetylacetone to the number of moles of the olefinically unsaturated double bond in the polymer 2 was 0.3 mol%. The operation was performed to hydrogenate the polymer. Table 1 shows the changes in the hydrogenation rate and the molecular weight distribution 4 hours after the start of the reaction.

[0034]

[Table 1]

[0035]

According to the hydrogenation method provided by the present invention, the unsaturated bond-containing polymer can be hydrogenated industrially advantageously.

Claims (3)

[Claims] 1. A method for hydrogenating a polymer containing an olefinically unsaturated double bond using a catalyst comprising an organometallic compound comprising a Group VIII metal and an organoaluminum compound. The compound is an alkylaluminum compound represented by the following formula (1) (R) ₃ Al (1) (wherein R represents an alkyl group having 6 or more carbon atoms), and a mole of aluminum in the organoaluminum compound. Number and the number
A method for hydrogenating a polymer containing an olefinically unsaturated double bond, wherein the molar ratio of the Group VIII metal is from 0.5 / 1 to 10/1. 2. The method for hydrogenating a polymer according to claim 1, wherein the polymer containing an olefinically unsaturated double bond is a polymer containing three or more substituted olefinically unsaturated double bonds. 3. The method for hydrogenating a polymer according to claim 1, wherein the polymer containing an olefinically unsaturated double bond is a polymer containing a structural unit derived from isoprene.