RU2205192C1 - Method of preparing conjugated diene copolymerization catalyst - Google Patents

Abstract

FIELD: polymerization catalysts. SUBSTANCE: conjugated diene copolymerization catalyst than may find use in production of general- destination rubbers is prepared via reaction, in hydrocarbon solvent, of catalyst components including rare-earth metal compounds, organohalogen compound, organoaluminum compound, and conjugated diene, said organohalogen compound being, in particular, carbon tetrachloride, which preliminarily undergoes reaction with part or all amount of organoaluminum compound at carbon tetrachloride-to-aluminum molar ratio (0.025-0.75):1 both and ambient or elevated temperature. Resulting product is then mixed with other components observing metal/aluminum/chlorine/diene molar ratio 1:(4-20):(3-3):(0.2-30). EFFECT: considerably reduced consumption of organoaluminum compound, lowered melting temperature of rubber, and increased frost resistance of vulcanized rubbers. 2 cl, 4 ex

Description

 The invention relates to methods for producing a conjugated diene copolymerization catalyst and may find application in the production of general-purpose rubbers in the synthetic rubber industry.

A known method of producing a catalyst for the copolymerization of conjugated dienes by reacting chelating halides of lanthanides, preferably lanthanum and cerium, with trialkylaluminum or dialkylaluminum hydride (US Patent 3,297,667 Cl 260-82.1, MKI ² C 08d, 1967). The starting lanthanide chelate halide is prepared by reacting anhydrous metal halides with a chelating agent, for example, salicylic aldehyde, aminophenol, hydroxyquinoline, oxalic acid, by boiling in ethanol for 24-40 hours. The solid product is isolated from ethanol and dried thoroughly. Then, an organoaluminum compound in a hydrocarbon solvent is added at room temperature. The molar ratio of lanthanide: halogen: aluminum is in the region of 1: 1-2.5: 25-100. The catalyst was kept at room temperature for 6-24 hours and then fed into an equimolar mixture of butadiene with isoprene in heptane. The temperature of the reaction mixture spontaneously rises within 1.5 hours to 72 ^{° C.} , and then drops to 37 ^° C. within 3 hours ^. The polymerization is interrupted and the copolymer yield is 18.2 kg / g-cerium atom. The content of butadiene and isoprene units in the copolymer corresponds to the amount of each monomer in the initial mixture.

 The disadvantages of the method include the complexity of the synthesis of lanthanide chelate halides, the use of relatively expensive and inaccessible compounds as a chelating agent, the duration of the catalyst preparation process, and a rather high consumption of an organoaluminum compound. In addition, the catalyst has a low activity, and the copolymer obtained using such a catalyst has insufficient stereoregularity (the content of cis-1.4 units does not exceed 95%).

 A known method of producing a catalyst for the copolymerization of diene hydrocarbons by the interaction of lanthanide alcoholates with trialkylaluminum or dialkylaluminum hydride and a halogen-containing compound, aluminum, boron, titanium, vanadium and molybdenum halides are selected (German Patent 2833721, C 08 F 36/00, 1978).

Catalysts can be prepared in the presence of diene hydrocarbons. The molar ratio of lanthanide: aluminum: halogen: diene is in the range 1: 1-120: 0.1-10: 5-50. The copolymerization of an equimolar mixture of butadiene and isoprene is carried out in a hydrocarbon solvent at a temperature of 10-80 ^o C. the Yield of the copolymer is 413.5 kg / g-atom of neodymium. Although the copolymers have a more regular microstructure than those obtained by the previous method, namely, the content of cis-1.4 units in the butadiene part is 98%, and in the isoprene part it is 95%, but it is not high enough. In addition, the activity of the catalyst is still quite low, and the copolymers obtained with its use have insufficiently good frost resistance. So, according to the authors of this application, the melting temperature of a sample of a copolymer with an intrinsic viscosity of 4.0 dl / g is minus 4 ^o C (DTA).

The closest in technical essence to the proposed method is a method for producing a catalyst for copolymerization of conjugated dienes by reacting in a hydrocarbon solvent compounds of individual lanthanides or a mixture thereof, mainly a carboxylate or neodymium alcoholate, with an organohalogen compound selected from the number of primary, secondary or tertiary alkyl-, cycloalkyl- , aryl-, alkylaryl-, vinyl-, alkoxy-, epoxyhalides, and trialkylaluminum or dialkylaluminum hydride (US Patent 4,444,903, MKI ³ C 08 F 4/62, 1984). The ratio of lanthanide: aluminum: halogen is in the range of 1: 30-200: 0.5-3. The components of the catalyst are mixed at room temperature in any order in the presence or absence of a small amount of monomer and incubated for 15 minutes. The catalyst is stable in time, has good activity. With an optimal molar ratio of the components of neodymium: aluminum: chlorine equal to 1: 50: 2, and a polymerization temperature of 60 ^o With the yield of the copolymer in 1 hour is more than 500 kg / g-atom of neodymium. The copolymer has a rather high intrinsic viscosity (more than 6 dl / g) and contains the amount of cis-1.4 units in the butadiene and isoprene parts, equal to 98-99% in total.

Despite the fact that the catalyst has good activity and allows to obtain copolymers with a high content of cis-1.4 units, it is not without a number of disadvantages. So, the organohalogen compounds used to prepare the catalyst are inaccessible and relatively expensive, and a high ratio of aluminum and neodymium (from 30: 1 to 200: 1) leads to an increase in the ash content in the copolymer. The composition of the resulting copolymer differs markedly from the composition of the initial mixture of monomers, for example, when 17% molar isoprene and 83% molar butadiene are introduced into the copolymerization zone, only 9% molar isoprene units are contained in the final product. The remaining amount of isoprene remains unpolymerized, which is economically disadvantageous and complicates the synthesis of copolymers with a given composition. In addition, the copolymers synthesized using the catalyst obtained by the described method have insufficiently good frost resistance, as evidenced by the reduced melting point of the copolymers with an intrinsic viscosity of 6.02 dl / g, equal to minus 9 ^° C (DTA).

 The objective of the proposed technical solution is to develop a method for producing a catalyst that can significantly reduce the consumption of organoaluminum compounds, using more affordable raw materials, as well as making it possible to obtain copolymers with improved frost resistance.

This object is achieved in that in the claimed method for producing a catalyst by reacting catalyst components in a hydrocarbon solvent, including a rare-earth metal compound, an organohalogen compound, an organoaluminum compound and a conjugated diene, carbon tetrachloride (CCl ₄ ) is used as the organohalogen compound, which is preliminarily reacted with a part or the entire amount of the organoaluminum compound with a molar ratio of CCl ₄ : aluminum equal to 0.025-0.75 both at room temperature and at elevated temperature, after which they are mixed at room temperature with other components with a molar ratio of rare earth metal: aluminum: chlorine: diene equal to 1: 4-20: 2-3: 0, 1-20.

The interaction of carbon tetrachloride with an organoaluminum compound is preferably carried out at a temperature of 50-70 ^o C.

The essence of the proposed method lies in the fact that in a glass reactor evacuated at 200 ^° C and filled with an inert gas, a solution of an organoaluminum compound in toluene is placed and carbon tetrachloride (GOST 20288-74) is added in an amount, usually corresponding to a molar ratio of CCl ₄ : aluminum, equal to 0.025-0.75, most preferably 0.025-0.50. The interaction is carried out both at room temperature and at elevated, but most preferably 50-70 ^o C, which provides a combination of achievable effect and the shortest time of synthesis.

 After cooling the solution to room temperature, it is mixed with a rare earth metal compound, a conjugated diene, and the remainder of the organoaluminum compound in any sequence. The molar ratio of rare earth metal: aluminum: chlorine: diene is 1: 4-20: 2-3: 0.1-20.

 Carboxylates or alcoholates formed by individual lanthanides with atomic number 57-71, for example neodymium (TU 48-4-186-72), praseodymium (TU 48-4-191-72), gadolinium (TU 48- 4-200-72), terbium (TU 48-4-190-72) or technical mixtures of metals, for example, the so-called "Didim", containing at least 85% neodymium and praseodymium from the sum of all metals (TU HELL 11.46-89), and acids, for example, petroleum, α- and α, α′-branched monocarboxylic (TU 2431-200-00203312-2000).

As organoaluminum compounds, trialkylaluminum is used, where alkyl is n- or iso-C ₁ -C ₁₀ alkyl, for example triethylaluminum (TU 6-02-638-76), triisobutylaluminum (TU 38.1031.54-79), diisobutylaluminum hydride (TU 6- 02-986-75), tetraalkylaluminoxane or mixtures thereof.

 Butadiene (TU 38.103658-88), isoprene (TU 38.103653-88), piperylene (TU 38.103300-83) can be used as conjugated dienes in the preparation of the catalyst.

 The organohalogen compound used as a catalyst component is obtained in aromatic hydrocarbons, preferably toluene, for the remaining components aliphatic, alicyclic, aromatic hydrocarbons can be used.

 After mixing the catalyst components, the mixture is incubated for 0.5 to 10 hours and used for copolymerization of conjugated dienes.

 As conjugated dienes, for example, butadiene, isoprene, piperylene can be used.

 The copolymerization is carried out in aliphatic, alicyclic, aromatic hydrocarbons or in a mixture of isoamylenes.

 The content of the sum of monomers in the solution is 10-20 vol.%.

The copolymerization is carried out at a temperature of 0-80 ^o C, preferably 20-60 ^o C.

 The viscosity of the copolymer can be controlled by a known method — introducing monomers in a hydrocarbon solvent into the solution before feeding the diisobutylaluminum hydride catalyst.

 At the end of the copolymerization, the catalyst is deactivated, and the copolymer is isolated by introducing ethanol containing 0.6 wt.% Agidol-2 [2,2'-methylene-bis (4-methyl-6-tert-butylphenol)] based on the copolymer as stabilizer. The copolymer is dried in vacuum to constant weight.

 The activity of the catalyst is evaluated in kg of copolymer obtained per 1 g-atom of rare-earth metal in 1 hour.

 The following are examples illustrating the invention.

Example 1
0.66 ml of triisobutylaluminium in toluene with a concentration of 0.4 mol / l are placed in a glass reactor with a magnetic stirrer, previously heated in vacuum and filled with dry argon, and 0.019 ml (0.2 mmol) of CCl ₄ is introduced with a syringe with stirring. The solution was heated to 70 ^° C. The molar ratio of CCI ₄ : aluminum was 0.75. The reaction mixture was incubated for 2 hours, then cooled to room temperature and 3.34 ml of a solution of triisobutylaluminum in toluene with a concentration of 0.4 mol / l, 1 ml of praseodymium 2-ethylhexanoate with a concentration in toluene of 0.4 mol / l and 0 were fed with stirring. , 35 ml (4 mmol) of butadiene. The molar ratio of praseodymium: aluminum: chlorine: butadiene is 1: 10: 2: 10.

After 2 hours, the mixture was used as a catalyst for the copolymerization of butadiene with isoprene. The molar ratio of butadiene to isoprene is 75:25. An 80-ml glass ampoule preheated and filled with dry argon is charged with 50 ml of a solution of butadiene and isoprene in cyclohexane containing 3.50 g of butadiene and 1.47 g of isoprene, the ampoule is thermostated at 40 ^° C and 0.12 ml of catalyst is added with a syringe. The molar ratio of the sum of monomers to praseodymium in this case is 20,000: 1.

After 1 hour, the copolymer is isolated. The copolymer yield is 886.5 kg / g praseodymium atom. The composition of the copolymer: 74.8 mol.% Butadiene and 25.2 mol.% Isoprene units. The cis-1.4 content is 99.0%, intrinsic viscosity 4.6 dl / g. The melting point T _PL (DTA) is minus 21 ^o C. The coefficient of frost resistance at -60 ^o With the vulcanizate of the copolymer reaches a value of 0.79.

Example 2
In a glass reactor with a magnetic stirrer, previously evacuated, heated and filled with dry argon, 20 ml of triethyl aluminum in toluene with a concentration of 0.4 mol / L are placed and, with stirring, 0.019 ml (0.2 mmol) of CCl ₄ is introduced with a microsyringe. The molar ratio of CCl ₄ : aluminum is 0.025. The temperature in the reactor was raised to 60 ^° C. The reaction mixture was kept for 0.5 hours. Then the solution is cooled to room temperature and 1 ml of neodymium naphthenate with a concentration of 0.4 mol / l in toluene and 0.004 ml of piperylene is fed with stirring. The molar ratio of neodymium: aluminum: chlorine: piperylene is 1: 20: 2: 0.1.

The mixture was incubated for 0.5 hours and used as a catalyst for the copolymerization of butadiene with isoprene. The molar ratio of butadiene and isoprene in the starting mixture is 90:10. A 50-ml solution of butadiene and isoprene in gasoline containing 4.19 g of butadiene and 0.59 g of isoprene is loaded into a glass ampoule preheated and filled with dry argon, the ampoule is thermostated at 60 ^° C and 0.227 ml of catalyst is added with a syringe. The molar ratio of the sum of monomers to neodymium is 20,000: 1.

After 1 hour, the copolymer is isolated. The copolymer yield is 930 kg / g-atom of neodymium. The copolymer consists of 89.8 mol.% Butadiene units and 10.2 mol.% Isoprene units, contains 99.2% cis-1.4 units and has a characteristic viscosity of 4.8 dl / g. The melting point T _PL (DTA) is minus 15 ^o C. The coefficient of frost resistance at -60 ^o With the copolymer vulcanizate is 0.69.

Example 3
In a glass reactor with a stirrer, heated in vacuo and filled with dry argon, 4 ml of triisobutylaluminium in toluene with a concentration of 0.4 mol / l are placed and, with stirring, 0.024 ml (0.25 mmol) of CCl ₄ is introduced with a microsyringe. The solution was heated to 50 ^° C. The molar ratio of CCl ₄ : aluminum was 0.156. After 3 hours, the solution was cooled to room temperature and, with stirring, it was fed into an ampoule, preheated, filled with argon, and containing 0.8 ml of isoprene and 1 ml of didim α, α′-dimethyl octanoate with a concentration of 0.4 mol / L in gasoline. The molar ratio of didim: aluminum: chlorine: isoprene is 1: 4: 2.5: 20. After 3 hours, the mixture was used as a catalyst for the copolymerization of butadiene with piperylene. The molar ratio of butadiene and piperylene is 90: 10. A 50 ml solution of butadiene and piperylene in a mixture of isoamylenes containing 4.19 g of butadiene and 0.59 g of piperylene is loaded into a preheated and filled with argon, the ampoule is thermostated at 20 ^° C and 0.062 is added ml of catalyst. The molar ratio of the sum of monomers to Didim is 20,000: 1.

 After 1 hour, the copolymer is isolated. The yield of copolymer is 894 kg / g-atom of didim.

The composition of the copolymer: 90.3% butadiene and 9.7% piperylene units. The content of CIS-1,4 units of 98.2%, a characteristic viscosity of 4.8 DL / g The melting point of T _PL (DTA) is -33 ^o C. The coefficient of frost resistance at -60 ^o With the copolymer vulcanizate is 0.75.

Example 4
In a glass reactor with a stirrer, heated in vacuo and filled with dry argon, 7 ml of triethylaluminum in toluene with a concentration of 0.4 mol / L was placed and 0.020 ml (0.210 mmol) CCl _{4 was} introduced with a microsyringe with stirring. The temperature in the reactor was maintained at 28 ^° C. The molar ratio of Cl ₄ : aluminum was 0.075. After 6 hours, the solution is fed into a vial preheated and filled with argon containing 10 ml of a solution of tetraisobutylaluminoxane in toluene with a concentration of 0.4 mol / l, 1 ml of a solution in toluene of α-ethyl, terbium α-butyl hexanoate with a concentration of 0.4 mol / l and 0.6 ml of piperylene. The molar ratio of terbium: aluminum: chlorine: piperylene is 1: 17: 2.1: 15.

The mixture was incubated for 10 hours and used as a catalyst for the copolymerization of butadiene with piperylene at a molar ratio of 70:30. For this purpose, a 50 ml solution of a mixture of monomers in toluene containing 3.26 g of butadiene, 1.76 g of piperylene, 1 ml of a solution of diisobutylaluminum hydride in toluene with a concentration of 0.1 mol / l, is loaded into an ampoule preheated in a vacuum and filled with argon. thermostat at 60 ^o C and add 0.31 ml of catalyst. The molar ratio of the sum of monomers to terbium is 15000: 1.

After 1 hour, the copolymer is isolated. The copolymer yield is 525 kg / g terbium atom. The composition of the copolymer: 70.8% butadiene and 29.2% piperylene units. The content of cis-1.4 units is 99.0%. Intrinsic viscosity 4.5 dl / g. The melting point of the copolymer is minus 36 ^o C. The coefficient of frost resistance at -60 ^o With the vulcanizate of the copolymer is 0.70.

 Thus, the proposed method can significantly reduce the consumption of organoaluminum compounds, using available raw materials. In addition, the application of the proposed method allows to obtain copolymers with high yield, while the ratio of monomer units in the copolymer corresponds to their content in the initial mixture of monomers. The application of the proposed method can significantly improve the low-temperature properties of polymers - to lower the melting point of rubbers, to increase the coefficient of frost resistance of rubbers based on them, so necessary for the manufacture of frost-resistant products in the production of rubber goods, tires, artificial leather, cables.

Claims (2)

 1. A method of producing a copolymerization catalyst for conjugated dienes by reacting catalyst components in a hydrocarbon solvent, including a rare-earth metal compound, an organohalogen compound, an organoaluminum compound and a conjugated diene, characterized in that carbon tetrachloride is used as an organohalogen compound, which is preliminarily reacted with part or all of organoaluminum compounds at a molar ratio of carbon tetrachloride od: aluminum, equal to 0.025-0.75 both at room temperature and at elevated, after which at room temperature they are mixed with other components with a molar ratio of rare earth metal: aluminum: chlorine: diene equal to 1: 4-20: 2 -3: 0.1-20. 2. A method of obtaining a catalyst for copolymerization of conjugated dienes according to claim 1, characterized in that the interaction of carbon tetrachloride with an organoaluminum compound is carried out at 50-70 ^o C.