CS268208B1 - Hydrogenation method of unsaturated polymers - Google Patents

Abstract

A method for hydrogenating unsaturated polymers containing hydrogenatable olefinic C-C bonds, preferably diene polymers and their copolymers with vinyl aromatic hydrocarbons such as poly(butadiene), poly(isoprene), butadiene-styrene and isoprene-styrene copolymers, catalyzed by nickel catalysts of the Ziegler type based on organonickel compounds and organoaluminum compounds of the general formula R^(R20)3_nAl, 1 2 where R denotes an ethyl group, R denotes an alkyl group containing one to eight carbon atoms, preferably methyl, ethyl, propyl and butyl groups and n is equal to 1 to 2.5 optionally sodium bis(2-methoxyethoxy)dialuminium hydride, consisting in that the hydrogenation is carried out in methyl-tert. butyl ether as a solvent.

Description

The present invention relates to a process for the hydrogenation of unsaturated polymers catalyzed by nickel catalysts of the Zlegler type using methyl tert-butyl ether as solvent.

It is known that the hydrogenation of polymers containing multiple bonds between carbon atoms is an industrial process to increase the oxidative stability of these products. The hydrogenation can be performed using a variety of heterogeneous and reaction-soluble catalysts, such as Raney nickel, nickel on diatomaceous earth (NSR Patent No. 1,106,961, Patent No. 2,322,234), Pd / CaCO 3 (J. Polym. Sel. , Polym. Phys. Ed. 17, 1211 (1979), 10% Pd on carbon and 1% Pt / AlgO-j (NSR Patent No. 2,845,615, Belgian Patent No. 871,348). soluble catalysts which have hitherto been obtained by reacting nickel compounds with trialkylanes, for example triethylalan (NSR Patent Nos. 2,322,234, 2,437,787, 2,748,884), organolithium compounds, in particular n-butyllithium (British Pat. No. 1,213,411 , Japanese Patent No. 70-39,556, U.S. Patent No. 3,541,064), sodium (Japanese Patent No. 71-02,381), organomagnesium compounds, e.g., diethylmagnesium (British Patent No. 1,213,411, U.S. Pat. U.S. Pat. No. 3,541,064), optionally complex hydrides, e.g. LIAIH 2 (British Pat. No. 1,229,573).

Hitherto, a narrow range of solvents from the class of cycloaliphatic or aromatic hydrocarbons, preferably cyclohexane and toluene, has been used in the treatment of unsaturated polymers by hydrogenation. This also applies to very efficient catalyst systems based on organic divalent nickel compounds, preferably nickel carboxylates or pentanediohates, and organoaluminum compounds of the general formula R (R 0) - Al (R denotes ethyl groups), R - denotes an alkyl group of 1 to 8 carbon atoms, n is equal to 1 to 2.5) (Czech Patent No. 226,096) and similar systems in which sodium bis (2-methoxyethoxy) aluminum dihydride (Czech Patent No. 227 105) acts as an activator.

Despite the undeniable advantages of the methods for hydrogenating unsaturated polymers described in the said authors' certificates, the use of defined solvents presents technical problems in cases where the production of an unsaturated polymer requires a different solvent. These are associated with the need to transfer the hydrogenated polymer to another solvent before the actual hydrogenation, usually by isolating it from the polymerization mixture and then dissolving it in an aromatic or cycloaliphatic solvent.

This applies not only to polymers produced by emulsion polymerization or copolymerization, but also to unsaturated polymers, reap, copolymers, the production of which uses anionic polymerization initiated, e.g. lithium adducts to conjugated dienes, in which ethereal solvents, preferably methyl tert. butyl ether, As described in MS. copyright certificate No. 229 066.

The hydrogenation process according to the invention eliminates the above-mentioned disadvantage. It is based on the finding that the catalytic activity in systems based on organic compounds of divalent nickel and alkylalkoxyalanes, resp. sodium bis (2-methoxyethoxy) aluminum dihydride can be generated in methyl tert-butyl ether as solvent. The catalysts thus prepared show high catalytic efficiency in the hydrogenation of solutions of unsaturated polymers in the same ethereal solvent.

Unsaturated polymers according to the invention are polymeric substances containing hydrogenable C = C bonds, preferably polymers formed by polymerization of conjugated dienes and their copolymerization with vinyl-substituted aromatic hydrocarbons. Examples of such unsaturated polymers are poly (butadiene), poly (isoprene), butadiene-styrene copolymer and butadiene-isoprene copolymer. Hydrogenation can be performed with both unfinished polymers and functional-terminated polymers. Although the above polymers can be produced by any of the known methods (e.g., bulk, emulsion copolymerization, etc.), to take full advantage of the hydrogenation process of the present invention, it is particularly advantageous to select anionic polymerization in methyl tert-butyl ether. The resulting solution of the product in this solvent can be directly hydrogenated after the addition of the catalyst. The polymer concentration is determined by technological and economic considerations. It is usually expedient to carry out, by hydrogenation, solutions containing polymer in a concentration of 1 to 25% by weight, preferably 5 to 15% by weight, depending on the viscosity of the solution, which may range from 2 to 1000 mPa s. C of the polymer bonds and the desired degree of hydrogenation, the hydrogenation is carried out without pressure or at a pressure of up to 10 MPa, at reaction temperatures of up to 130 ° C, preferably at temperatures of 40 to 50 ° C. It has been found that under the above conditions, the aliphatic double bonds of the polymer are selectively hydrogenated without the reaction being significantly accompanied by undesired degradation of the polymer. The following examples illustrate the process of the invention without limiting or limiting it.

Example 1

1.2 mmol of nickel pentane-2,4-dionate was introduced into the reaction vessel under nitrogen, 9.1 ml of methyl tert-butyl ether was added, and the mixture was heated to 50 ° C under an internal atmosphere with stirring. After five minutes, 5 ml of a 10% solution of triethylalan in methyl tert-butyl ether was gradually added to the mixture, and heating was continued for another 15 minutes. The reaction mixture was then cooled to room temperature. The catalytic activity of the resulting system is illustrated in Table 1.

Example 2

Example 1 was repeated except that a 10% solution of sodium bis (2-methoxyethoxy) aluminum dihydride in methyl tert-butyl ether was used instead of triethylalan (in this case the mixture contained a small amount of toluene in which said hydride is produced as a 70% solution. under the name Synhydrid, lachema Kolín). The effectiveness of this system is documented in Table 1.

Example 3.

The example was repeated except that nickel 2-ethylhexanoate was used as a precursor instead of nickel pentanedione. The properties of this system are listed in Table 1.

Example 4

The example was repeated except that the following solvents were used sequentially to prepare the catalyst: cyclohexane, toluene, tetrahydrofuran. The hydrogenation activity of the catalysts thus obtained is summarized in Table 1.

Example 5

After deaeration and hydrogenation, 110 volumes of a solution of the hydrogenated polymer in methyl tert-butyl ether were charged to a pressure hydrogenation reactor equipped with a stirrer, a hydrogen inlet and a metering meter, and 10 volumes of the catalyst solution of Examples 1 to 1 were added with stirring. 4. The hydrogen pressure was then adjusted to the desired value and the hydrogenation was performed at 40 ° C. The results are summarized in Table 1.

Table 1

The catalyst of the example Solvent ^and its preparation Hydrogenation (MTBE) substrate reaction pressure degree of hydrogenation,% thanks in MPa time, min 1 MTBE PBT 0.12 25 99 2 MTBE-T1 PBT 0.14 32 97 Solpren 1205 0.14 60 87 3 MTBE PBT 0.12 27 96 4 CHX PBT 0.12 50 92 TL 0.12 45 90 THF 0, 12 45 90

a - MTBE methyl tert-butyl ether, TL toluene, CHX cyclohexane, THF tetrahydrofuran b - PBT poly (butadlene) (average molecular weight 61,000), used as a 7% solution in MTBE and a 5% solution in other solvents, Solpren 1205 is a block styrene-butadiene copolymer with * 80,000, was used as a 2.5% solution in MTBE

Claims (2)

OBJECT OF THE INVENTION A process for the hydrogenation of unsaturated polymers containing hydrogenable C 1 -C olefinic bonds, preferably diene polymers and their copolymers with vinylaromatic hydrocarbons such as poly (butadiene), poly (isoprene), butadiene-styrene and isoprene-styrene copolymers, catalyzed by nickel Ziegler catalysts. type based on organic nickel compounds and organoaluminum compounds of general formula Wherein R is ethyl, R is alkyl of one to eight carbon atoms, preferably methyl, ethyl, propyl and butyl, and n is 1 to 2.5, optionally sodium bis (2-methoxyethoxy) aluminum dihydrochloride in a molar ratio. 1: 0.5 to 1: 5, characterized in that the hydrogenation is carried out in methyl tert. butyl ether as solvent. 2. The process according to claim 1, characterized in that the hydrogenation is carried out in mixed solvents containing methyl tert-butyl ether, preferably in a mixture of methyl tert-butyl ether and cyclohexane and methyl tert-butyl ether with toluene.