RU2136699C1 - Diene (co)polymer hydrogenation process - Google Patents

Abstract

FIELD: rubber industry. SUBSTANCE: invention relates to hydrogenation of carbo-chain polymers and can be used for production of rubber products applied in various areas. Diene (co)polymers are treated with hydrogen in hydrocarbon solvent in presence of catalytic system consisting of nickel compounds, trialkylaluminum, and a modifying additive, in particular, compound of formula (RCOO)₃Fe wherein R is C₅-C₁₆-alkyl at molar ratio nickel/modifier/trialkylaluminum (0.1-0.9):90.9-0.1):(3-6) and amount of nickel 0.01 to 0.5% of unsaturated (co)polymer weight. EFFECT: increased degree of hydrogenation and simplified removal of catalyst from product. 1 tbl, 11 ex

Description

 The invention relates to the production of hydrogenated carbochain polymers and can be used in the synthetic rubber industry to obtain materials used in the automotive, medical, electrical and other industries.

A known method of hydrogenation of (co) polymers of dienes by treatment with hydrogen in a hydrocarbon solvent in the presence of a triple catalyst composition consisting of an organometallic compound of an iron group, a lithium or organoaluminum compound and a modifying additive. As a modifying additive, copolymers of butadiene with styrene are used (US Pat. No. 3,531,445; C 08 F 27/25; claimed 15.04.69, published 29.09.70)
The specified additive does not sufficiently improve the activity of the catalytic composition and, in addition, when using there are technological difficulties associated with cleaning the polymer from the catalyst and cleaning the return solvent.

 The closest in technical essence and the achieved result to the alleged invention is a method for the catalytic hydrogenation of diene polymers (US Pat. Germany 2748884; C 08 F 8/04; application. 2.11.77, publ. 3.05.79) in the presence of a catalytic system based on organic compounds nickel, trialkylaluminium and water used as a modifying additive.

 The disadvantage of this method is the insufficiently high degree of hydrogenation of the polymers and technological difficulties associated with the introduction of water into the system, as well as with the destruction and removal of the catalyst due to the formation of polymer aluminoxanes from trialkyl aluminum in the system.

 The technical task of the invention is to increase the degree of hydrogenation of polymers by increasing the activity of the catalytic system and simplifying the conditions for separation of the catalyst.

The problem is solved in that the method of hydrogenation of (co) polymers of dienes is carried out by treating with hydrogen in a hydrocarbon solvent in the presence of a catalytic system consisting of nickel, trialkylaluminum compounds and a modifying additive, which is used as a compound of the general formula (RCOO) ₃ Fe, where R - alkyl C ₅ -C ₁₆ , at a molar ratio of nickel compound: modifying additive: trialkylaluminum (0.1-0.9): (0.9-0.1): (3: 6) and a dosage of nickel 0.01- 0.5% by weight of unsaturated (co) polymer.

The use of the organo-iron compound (RCOO) ₃ Fe in the catalyst system, where R is alkyl with a C ₅ -C ₁₆ hydrocarbon chain length, partially water-soluble salts are obtained with a hydrocarbon chain length below C ₅ , which leads to technological difficulties associated with the disposal of effluents in the process synthesis of compounds. With a hydrocarbon chain length above C ₁₆ , salts are obtained that are hardly soluble in hydrocarbon solvents and form heterogeneous complexes with low activity.

 With the ratio of nickel compound: modifying additive: trialkylaluminum (0.1-0.9) :( 0.9-0.1) :( 3: 6) a high catalytic activity of the system is achieved.

 The nickel compound is dosed based on a nickel content of 0.01-0.5% by weight of the unsaturated (co) polymer, and a high rate and degree of hydrogenation of the copolymers are achieved. When the dosage of nickel is less than 0.01%, the reaction slows down in time, a dosage of more than 0.5% by weight of the unsaturated (co) polymer is undesirable due to overuse of the catalyst.

Hydrogenation is carried out under mild conditions at a hydrogen pressure of 0.01-0.5 MPa and a temperature of 20-70 ^o C. The hydrogenation time is 0.1-1.0 hours and varies only by the possibility of heat removal of the reaction. The choice of solvent is determined by polymer synthesis conditions or hydrogenation conditions, and aliphatic aromatic or mixed solvents may be used. Linear or cyclic ethers (diglyme, tetrahydrofuran), which are used in the synthesis of (co) polymers for hydrogenation and are contained in the polymerizate, do not affect the activity of the catalytic system.

The catalytic system is prepared at 10-50 ^o C by adding a solution of trialkylaluminum to a mixture of nickel salts and a modifying additive in a selected ratio in an inert atmosphere (nitrogen, argon), followed by aging for 30 minutes with stirring.

 The content of double bonds in polymers after hydrogenation was determined by the ozonation method.

 The metal content in the polymers was determined by X-ray powder diffraction (X-ray fluorescence analysis).

 The invention is illustrated by examples of specific purposes.

 Example 1

 In a 200 ml reactor, a solution of 10 g of a styrene butadiene copolymer of structure B / C-C in 140 ml of a mixed solvent is loaded. The polymer contains 55.4 wt.% Bound styrene, of which 17.5% are in the form of a “C” block, 38% are 1,2 units and has a weight average molecular weight of 130,000 (on a polystyrene scale).

The reactor was purged with argon, after which the catalytic system (11.15 ml) was added, obtained by mixing at 30 ^° C in argon 18 ml of a mixed solvent, 1 ml of a 0.1705 M solution of nickel 2-ethylhexanoate, 0.95 ml of a 0.1792 M solution Iron 2-ethylhecoanoate and 2.3 ml of a 0.295 M solution of triisobutylaluminum (TIBA). The ratio of Nickel salt: iron salt: TIBA 0.5: 0.5: 4 and the dosage of Nickel on the polymer of 0.05 wt.%.

Hydrogenation is carried out at 50 ^o C and a hydrogen pressure of 0.2 MPa.

To destroy and remove the catalyst, the polymer solution after hydrogenation is heated to 65 ^o C, add 0.5 ml of water, mix and after 10-15 minutes the precipitate is separated by centrifugation.

 The results are shown in the table at the end of the description.

 Example 2 (prototype).

0.9 L of butadiene and 0.5 L of styrene are dissolved in 4.8 L of cyclohexane in the presence of 15 ml of tetrahydrofuran. To the solution was added 16.5 ml of a 10% solution of n-butyllithium in hexane and the polymerization was carried out for 1 hour at 60-70 ^° C. 0.3 g of nickel acetylacetonate, 9 ml of toluene and 11 ml of 10% were added to the solution of the obtained styrene-butadiene copolymer a solution of triisobutylaluminum in hexane. The components of the catalytic system are mixed at a temperature of 25-30 ^o C. Then add 0.3 ml of water (14 mol per 1 mol of nickel acetylacetonate), the absorption of hydrogen occurs, which ends after 1 hour.

 Example 3

 Similarly to that described in Example 1, the styrene-butadiene copolymer of structure B / C-C is hydrogenated in the presence of the catalytic system 2-ethylhexanoate nickel: 2-ethylhexanoate iron: TIBA, varying the ratio of components in the complex at a fixed value of TIBA.

 The results are shown in the table.

 Example 4

 Similarly to example 1, the styrene-butadiene copolymer of structure B / C-C is hydrogenated in the presence of the catalytic system 2-ethylhexanoate nickel: 2-ethylhexanoate iron: TIBA, varying the ratio of TIBA at the optimum value of nickel salt: iron salt 0.5: 0.5 .

 The results are shown in the table.

 Example 5

 Similarly to that described in Example 1, the styrene-butadiene copolymer of structure B / C-C is hydrogenated in the presence of the catalyst system 2-ethylhexanoate nickel: 2-ethylhexanoate iron: TIBA with a fixed ratio of components 0.5: 0.5: 4, varying the dosage of nickel per polymer .

 The results are shown in the table.

 Example 6

Similarly to that described in example 1, the styrene-butadiene copolymer of structure B / C-C is hydrogenated in the presence of the catalyst system 2-ethylhexanoate nickel: iron carboxylate (RCOO) ₃ Fe: TIBA, varying the substituent (R) in the carboxylate with a molar ratio of components of 0.6: 0.4: 3.

 The results are shown in the table.

 Example 7

 Similar to the example in Example 1, a styrene-butadiene block copolymer of the C-B-C structure containing 30.2 wt.% Bound styrene, 42% of 1,2 units with a weight average molecular weight of 72,000 (on a polystyrene scale) was hydrogenated using the catalytic system various nickel and triethylaluminum compounds in combination with iron 2-ethylhexanoate.

 The results are shown in the table.

 Example 8

Hydrogenated polyisoprene lithium polymerization with a molecular weight of 85,000 (viscometric data) in the presence of the catalyst system of example 1. At a temperature of 60 ^o C and a hydrogen pressure of 0.5 MPa after 1 hour, the degree of hydrogenation is 97.6%.

 Example 9

Isoprene copolymer with styrene of structure С-И-С with a molecular weight of 68000 (in a polystyrene scale) is hydrogenated in the presence of the catalytic system of Example 1. At a temperature of 40 ^° C. and a hydrogen pressure of 0.5 MPa, the degree of hydrogenation is 96.5%.

 Example 10

 The butadiene copolymer with styrene of the structure B / C-C-B was hydrogenated in the presence of the catalytic system of Example 1, using toluene, cyclohexane, nephras as a solvent. The results shown in the table show that the solvent does not affect the activity of the catalyst composition.

 Example 11

Hydrogenated lithium polymerization polybutadiene with a molecular weight of 150,000 and a content of 1,2 units of 42% in the presence of the catalytic system of example 1 with a ratio of components of 0.8: 0.2: 3 and a dosage of nickel of 0.1%. At a temperature of 50 ^o C and a hydrogen pressure of 0.5 MPa after 0.5 hours, the degree of hydrogenation is 99%.

 The results are shown in the table.

 From the data in the table shows that the proposed method allows to achieve a high degree of hydrogenation of polymers and to simplify the removal of the catalyst from the polymer after hydrogenation, the catalyst is easily destroyed by water and can be removed by known methods, such as sludge, filtration, centrifugation.

Claims (1)

A method for hydrogenating diene (co) polymers by treatment with hydrogen in a hydrocarbon solvent in the presence of a catalytic system consisting of nickel, trialkylaluminum compounds and a modifying additive, characterized in that the compound of the general formula (RCOO) ₃ Fe is used as a modifying additive, where R is alkyl C ₅ - C ₁₆ , with a molar ratio of nickel compound: modifying additive: trialkylaluminum (0.1 - 0.9): (0.9 - 0.1): (3 - 6) and a dosage of nickel of 0.01 - 0, 5% by weight of unsaturated (co) polymer.

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