CA2316770A1 - A process for the preparation of a copolymer based on vinyl aromatic compounds and conjugated dienes and the use thereof for the manufacture of vulcanizates with outstanding damping behavior - Google Patents
A process for the preparation of a copolymer based on vinyl aromatic compounds and conjugated dienes and the use thereof for the manufacture of vulcanizates with outstanding damping behavior Download PDFInfo
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F236/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
- C08F236/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
- C08F236/04—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
- C08F236/10—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated with vinyl-aromatic monomers
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Abstract
According to the process of the invention, copolymers based on vinyl aromatic compounds and conjugated dimes with an average molecular weight (Mn) from 50,000 to 600,000 g/mole, a vinyl aromatic compound content from S to 50 wt.%
and a conjugated dime content from SO to 95 wt.% are prepared by reacting a vinyl aromatic compound with a conjugated dime in the presence of a lithium metal-containing initiator, wherein polymerization is controlled such that the damping in the glass process encompasses a frequency range which is characterized in that the half width of the maximum of the loss factor tan 8 is greater than 3 frequency decades.
and a conjugated dime content from SO to 95 wt.% are prepared by reacting a vinyl aromatic compound with a conjugated dime in the presence of a lithium metal-containing initiator, wherein polymerization is controlled such that the damping in the glass process encompasses a frequency range which is characterized in that the half width of the maximum of the loss factor tan 8 is greater than 3 frequency decades.
Description
Le A 33 727-Foreign Countries Bg/ngb/NT
A PROCESS FOR THE PREPARATION OF A COPOLYMER BASED ON
VINYL AROMATIC COMPOUNDS AND CONJUGATED DIENES AND
THE USE THEREOF FOR THE MANUFACT URE OF VULCANIZATES
WITH OUTSTANDING DAMPING BEHAVIOR
FIELD OF THE INVENTION
The present invention provides a process for the preparation of a copolymer based on vinyl aromatic compounds and conjugated dimes and the use thereof for the manufacture of vulcanizates with outstanding damping behavior, coupled with particularly good wet skid behavior and combined with good processability of the copolymers during the manufacture of corresponding vulcanizates.
It is well known to improve the wet skid behavior (wet skid safety) of styrene-butadiene copolymers by increasing the breadth of dispersion of the vinyl content or of the styrene content. DE 31 15 878, EP 0 530 795 and EP 553 689 should be mentioned, in particular, in this connection. A disadvantage of the styrene-butadiene copolymers described in the patent publications mentioned is, in particular, the complicated method of preparation thereof, wherein it. is important to ensure 1) that a particular temperature gradient is observed during the reaction or 2) that the amount of modifier or of monomers increases constantly during the reaction, entailing a special monitoring operation during polymerization.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a simplified process for the preparation of copolymers based on vinyl aromatic compounds and conjugated dimes which does not require a particularly laborious monitoring of the monomers to Le A 33 727-Foreign Countries be used, the temperature and the amount of modifier. Moreover, the copolymers and vulcanizates thereof should have improved wet skid behavior and outstanding damping behavior and good processing behavior during the manufacture of corresponding vulcanizates from the copolymers.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides, therefore, a process for the preparation of copolymers based on vinyl aromatic compounds and conjugated dimes with an average molecular weight (Mn) from 50,000 to 600,000 g/mole, a vinyl aromatic compound content from 5 to 50 wt.% and a conjugated dime content from 50 to 95 wt.%, which is characterized in that a vinyl aromatic compound is reacted with a conjugated dime in the presence of a lithium metal-containing initiator, polymerization being controlled such that the damping in the glass process encompasses a frequency range which is characterized in that the half width of the maximum of the loss factor tan b is greater than 3, preferably 3.5 to 6, more preferably 4 to 6 frequency decades.
Due to the continuously changing vinyl aromatic compound content in the polymer chain in the process according to the present invention, the damping behavior in the glass transition zone of the copolymer also changes. The damping behavior in the glass transition zone can then be characterized by measuring the half width of the loss factor tan 8.
Frequency spectra of the complex shear modulus are prepared in order to determine the half width of the loss factor tan 8 (see, in this connection, the dissertation by C.
Wrana, University of Ulm, 1996, p. 2-23). By applying the frequency/temperature superposition principle, the apparatus-related frequency range of the shear modulus spectra of the measuring device used may be extended to the relevant frequency range. From the maximum of the loss factor tan 8, which is caused by the glass relaxation process in the case of elastomers and can be found in a frequency range Le A 33 727-Foreign Countries from 1 Hz to 1 GHz at a reference temperature of 20°C, the half width is determined by subtraction of the two loss factors and which lie at greater and lower frequencies than the maximum and amount to exactly half of the maximum value.
According to the process of the present invention, copolymers are prepared preferably on the basis of vinyl aromatic compounds and conjugated dimes having an average molecular weight (Mn) from 100,000 to 500,000 g/mole (determined by gel permeation chromatography with polystyrene as the standard), an aromatic vinyl compound content from 10 to 45 wt.% and a conjugated dime content from 55 to 90 wt. %.
Conjugated dimes, which may be used in the process according to the present invention, are 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 1-phenyl-1,3-butadiene, 1,3-hexadiene and 1,3-heptadiene. 1,3-butadiene and isoprene are preferably used.
Vinyl aromatic compounds which may be used in the process according to the invention in addition to styrene are p-methylstyrene, a-methylstyrene, 3,5-dimethyl-styrene, vinylnaphthalene, p-tert.-butylstyrene, divinylbenzene and diphenylethylene, preferably styrene.
The vinyl aromatic compounds and the conjugated dimes may be used individually or in mixture as monomers for the preparation of the copolymers.
Suitable lithium metal-containing initiators for the process according to the present invention are the lithium metal-containing initiators well known for anionic polymerization, for example, n-butyllithium, sec.-butyllithium, tert.-butyllithium, n-propyllithium, isopropyllithium, ethyllithium, cyclohexyllithium, phenyllithium and 2-naphthyllithium, preferably n-butyllithium.
Le A 33 727-Foreign Countries The lithium metal-containing initiators are normally used in the process according to the present invention in amounts from 0.1 to 1 S mmole, preferably 0.2 to 10 mmole, based on 100 g of polymer.
It may be advantageous for the process according to the present invention if alkali metal compounds are used in addition to the lithium metal-containing initiators.
The alkali metal compounds may be selected from alkali metal compounds according to the following general formulae:
R1M, R20M, R3COOM and R4RSNM, wherein Rl, R2, R3, R4 and RS is an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or a partially substituted group thereof, and M is Na, K, Rb or Cs.
Examples of an alkali metal compound having the formula RtM include compounds such as methylsodium, ethylpotassium, n-propylrubidium, ethylcaesium, t-butylsodium, t-amylpotassium, n-hexylrubidium, 4-methylcyclohexyl sodium, 3-hexenylpotassium, 2,5-decadienylrubidium, 4,6-di-n-butyldecylsodium, phenyl-potassium, benzylsodium and 4-tolylpotassium.
Alkali metal compounds having the formula RZOM which may be used are alkali metal salts of mono- and polyhydric alcohols and phenols such as sodium, potassium, rubidium or caesium salts of methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, t-butyl alcohol, t-amyl alcohol, n-hexyl alcohol, cyclohexylalcohol, 2-butenyl alcohol, 4-methylcyclohexenyl alcohol, 3-cyclo-pentenyl alcohol, 3-hexenylalcohol, 2,5-decadienyl alcohol, allyl alcohol, 1,3-dihydrohexane, 1,5,9-trihydroxytridecane, benzyl alcohol, phenol, catechol, Le A 33 727-Foreign Countries resorcinol, hydroquinone, pyrogallol, 1-naphthol, 2-naphthol, 2,6-di-t-butyl-4-methylphenol, 2,4,5,6-tri-t-butylphenol, n-nonylphenol and 1,12-dodecane diol.
Alkali metal compounds having the formula R3COOM which may be used are alkali metal salts of mono- or polyvalent carboxylic acids such as sodium, potassium, rubidium or caesium salts of lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, sebacic acid, phthalic acid and 1,8,16-hexadecanetoloyl carboxylic acid.
Alkali metal compounds having the formula R4RSNM which may be used are alkali metal salts of secondary amines such as sodium, potassium, rubidium or caesium salts of dimethylamine, di-n-butylamine, methyl-n-hexylamine, di-(3-hexenyl)amine, diphenylamine and dibenzylamine.
Alkali metal-containing alcoholates are used in preference in the process according to the present invention, such as sodium, potassium, rubidium or caesium salts of methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, tert.-butyl alcohol, tert.-amyl alcohol, n-hexyl alcohol, cyclohexylalcohol, butyl alcohol, phenol and 1-naphthol. More particularly preferably, the potassium salt of tert.-amyl alcohol is used.
The alkali metal compounds are normally used in the process according to the present invention in an amount such that the molar ratio of lithium metal-containing initiator to alkali metal compounds is 1 : 0.005 to 1 : 0.25.
Of course, it is also possible to carry out the process according to the invention in the presence of so-called modifiers such as ethers and/or amine compounds such as tertiary amines, which are capable of controlling the vinyl content in the polymer chain. More particularly, ether compounds and amine compounds which may be mentioned include triethylamine, pyridine, tetramethylethylene diamine (TMEDA), tetrahydrofuran (THF), diethylether, diphenylether, anisole, ethylene glycol Le A 33 727-Foreign Countries dimethylether, ethylene glycol diethylether, ethylene glycol ethyl-tert.-butyl ether, 2,2-bis-(2-oxolanyl)propane, and oligomeric oxolanyl alkanes. The modifiers mentioned may be used both individually and in mixture.
The optimum amount of modifiers to be used may be determined easily by appropriate preliminary tests and depends on the desired vinyl group content in the polymer chain. Amounts from about 0.005 to 400 mmole per 100 g of monomers used are customary.
The process according to the present invention may be earned out at temperatures from about 40°C to 160°C, preferably 50°C to 130°C. The process according to the present invention may be carried out at a pressure below atmospheric, at normal pressure and at elevated pressure, preferably at elevated pressure, for example, at pressures from 1 to 10 bar.
The process according to the present invention may be carried out both continuously and batchwise.
The process according to the present invention is earned out in the presence of the conventional inert solvents which are well known for anionic polymerization.
These are, more particularly, aromatic and/or aliphatic hydrocarbons with 2 to 12 carbon atoms, such as ethane, propane, iso- and n-butane, iso- and n-pentane, iso-and n-hexane, iso- and n-heptane, iso- and n-octane, cyclobutane, cyclopentane, cyclo-hexane, cycloheptane, cyclooctane, where n-hexane and cyclohexane are preferable.
The solvents may be used both individually and in mixture, and of course in the form of their isomer mixtures.
The most favourable amount of solvent in each case may also be determined easily by appropriate preliminary tests.
Le A 33 727-Foreign Countries _7_ The copolymers prepared according to the present invention based on aromatic vinyl compounds and conjugated dimes are suitable for the manufacture of vulcanizates which have outstanding damping behavior coupled with superior wet skid behavior, which is why the copolymers prepared according to the present invention are S particularly suitable for the manufacture of tires, preferably tire treads.
Of course, other vulcanized molded articles in which the above-mentioned physical properties are of importance may be manufactured from the copolymers according to the present invention.
EXAMPLES
The polymerization reactions were carried out under nitrogen with the exclusion of air and moisture.
The determination of the styrene content in the polymer and of the selectivity of polybutadiene (1,4-cis, 1,4-trans and 1,2-content) is carried out by IR
spectroscopy, the damping behavior and the determination of the half width of the loss factor by frequency-dependent measurements of complex material quantities.
Examples 1 to 4 Polymerization Polymerization was earned out in a 2 liter Buchi glass autoclave with stirrer and jacket heating. The amounts of styrene, 1,3-butadiene, hexane (mixture of isomers), initiator solution (n-butyllithium in n-hexane), alkali metal alcoholate potassium-tert.-amylate (KTA) and modifier diethoxyethane (DEE) given in Table 1 were added under nitrogen. The temperature was set at 60°C. After complete conversion had been achieved (about 2 h), the polymer was isolated by precipitation of the polymer solution in ethanolBHT (2,6-di-tert.-butyl-4-methylphenol) and dried at 60°C in a Le A 33 727-Foreign Countries _g_ vacuum drying oven until a constant weight was obtained. The batch sizes, reaction conditions and the properties of the polymers obtained are given in Table 1.
Table 1: Examples 1 to 4 S
Example 1 2 3 4 Polymerization BuLi in mmole 1.13 1.13 1.13 1.13 Hexane in g 850 850 850 850 Styrene in g 37.5 37.5 37.5 37.5 1,3-butadiene in g 112.5 112.5 112.5 112.5 KTA in mmole 0 0.023 0.057 0.283 DEE in mmole 1.75 1.75 1.75 1.75 Polymer Styrene content in wt.% 23.1 23.8 23.7 23.9 Butadiene content in 76.9 76.2 76.3 76.1 wt.%
cis in % 12.3 12.0 12.4 16.0 trans in % 18.3 17.2 17.5 24.4 1,2- in % 46.3 47.0 46.4 35.7 Half width in log (f/Hz)4.4 3 3 6.3 Frequency position in 5.3 4.4 4.7 -0.6/9.8 log (f/Hz) Examples 5-8 Polymerization Polymerization was carried out in the same way as in Examples 1 to 4, but without the use of an ether. The quantities used, the reaction conditions and the properties of the resulting polymers are shown in Table 2.
Le A 33 727-Foreign Countries Table 2: Examples 5 to 8 Example 5 6 7 g Polymerization BuLi in mmoles 1.25 1.25 1.25 1.25 Hexane in g 850 850 850- 850 Styrene in g 37.5 37.5 37.5 37.5 1,3-butadiene in g 112.5 112.5 112.5 112.5 KTA in mmoles 0 0.063 0.125 0.25 Polymer Styrene content in wt.% 25.5 26.2 26.4 26.1 Butadiene content in 74.5 73.8 73.6 73.9 wt.%
cis in % 30.0 28.7 27.4 25.6 trans in % 37.4 35.9 34.4 32.4 1,2- in % 7.1 9.2 11.8 15.9 Half width in log (f/Hz)4.4 4.3 3.7 5.0 Frequency position in 6.9 6.5 6.0 ~ 5.6 log (f/Hz)
A PROCESS FOR THE PREPARATION OF A COPOLYMER BASED ON
VINYL AROMATIC COMPOUNDS AND CONJUGATED DIENES AND
THE USE THEREOF FOR THE MANUFACT URE OF VULCANIZATES
WITH OUTSTANDING DAMPING BEHAVIOR
FIELD OF THE INVENTION
The present invention provides a process for the preparation of a copolymer based on vinyl aromatic compounds and conjugated dimes and the use thereof for the manufacture of vulcanizates with outstanding damping behavior, coupled with particularly good wet skid behavior and combined with good processability of the copolymers during the manufacture of corresponding vulcanizates.
It is well known to improve the wet skid behavior (wet skid safety) of styrene-butadiene copolymers by increasing the breadth of dispersion of the vinyl content or of the styrene content. DE 31 15 878, EP 0 530 795 and EP 553 689 should be mentioned, in particular, in this connection. A disadvantage of the styrene-butadiene copolymers described in the patent publications mentioned is, in particular, the complicated method of preparation thereof, wherein it. is important to ensure 1) that a particular temperature gradient is observed during the reaction or 2) that the amount of modifier or of monomers increases constantly during the reaction, entailing a special monitoring operation during polymerization.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a simplified process for the preparation of copolymers based on vinyl aromatic compounds and conjugated dimes which does not require a particularly laborious monitoring of the monomers to Le A 33 727-Foreign Countries be used, the temperature and the amount of modifier. Moreover, the copolymers and vulcanizates thereof should have improved wet skid behavior and outstanding damping behavior and good processing behavior during the manufacture of corresponding vulcanizates from the copolymers.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides, therefore, a process for the preparation of copolymers based on vinyl aromatic compounds and conjugated dimes with an average molecular weight (Mn) from 50,000 to 600,000 g/mole, a vinyl aromatic compound content from 5 to 50 wt.% and a conjugated dime content from 50 to 95 wt.%, which is characterized in that a vinyl aromatic compound is reacted with a conjugated dime in the presence of a lithium metal-containing initiator, polymerization being controlled such that the damping in the glass process encompasses a frequency range which is characterized in that the half width of the maximum of the loss factor tan b is greater than 3, preferably 3.5 to 6, more preferably 4 to 6 frequency decades.
Due to the continuously changing vinyl aromatic compound content in the polymer chain in the process according to the present invention, the damping behavior in the glass transition zone of the copolymer also changes. The damping behavior in the glass transition zone can then be characterized by measuring the half width of the loss factor tan 8.
Frequency spectra of the complex shear modulus are prepared in order to determine the half width of the loss factor tan 8 (see, in this connection, the dissertation by C.
Wrana, University of Ulm, 1996, p. 2-23). By applying the frequency/temperature superposition principle, the apparatus-related frequency range of the shear modulus spectra of the measuring device used may be extended to the relevant frequency range. From the maximum of the loss factor tan 8, which is caused by the glass relaxation process in the case of elastomers and can be found in a frequency range Le A 33 727-Foreign Countries from 1 Hz to 1 GHz at a reference temperature of 20°C, the half width is determined by subtraction of the two loss factors and which lie at greater and lower frequencies than the maximum and amount to exactly half of the maximum value.
According to the process of the present invention, copolymers are prepared preferably on the basis of vinyl aromatic compounds and conjugated dimes having an average molecular weight (Mn) from 100,000 to 500,000 g/mole (determined by gel permeation chromatography with polystyrene as the standard), an aromatic vinyl compound content from 10 to 45 wt.% and a conjugated dime content from 55 to 90 wt. %.
Conjugated dimes, which may be used in the process according to the present invention, are 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 1-phenyl-1,3-butadiene, 1,3-hexadiene and 1,3-heptadiene. 1,3-butadiene and isoprene are preferably used.
Vinyl aromatic compounds which may be used in the process according to the invention in addition to styrene are p-methylstyrene, a-methylstyrene, 3,5-dimethyl-styrene, vinylnaphthalene, p-tert.-butylstyrene, divinylbenzene and diphenylethylene, preferably styrene.
The vinyl aromatic compounds and the conjugated dimes may be used individually or in mixture as monomers for the preparation of the copolymers.
Suitable lithium metal-containing initiators for the process according to the present invention are the lithium metal-containing initiators well known for anionic polymerization, for example, n-butyllithium, sec.-butyllithium, tert.-butyllithium, n-propyllithium, isopropyllithium, ethyllithium, cyclohexyllithium, phenyllithium and 2-naphthyllithium, preferably n-butyllithium.
Le A 33 727-Foreign Countries The lithium metal-containing initiators are normally used in the process according to the present invention in amounts from 0.1 to 1 S mmole, preferably 0.2 to 10 mmole, based on 100 g of polymer.
It may be advantageous for the process according to the present invention if alkali metal compounds are used in addition to the lithium metal-containing initiators.
The alkali metal compounds may be selected from alkali metal compounds according to the following general formulae:
R1M, R20M, R3COOM and R4RSNM, wherein Rl, R2, R3, R4 and RS is an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or a partially substituted group thereof, and M is Na, K, Rb or Cs.
Examples of an alkali metal compound having the formula RtM include compounds such as methylsodium, ethylpotassium, n-propylrubidium, ethylcaesium, t-butylsodium, t-amylpotassium, n-hexylrubidium, 4-methylcyclohexyl sodium, 3-hexenylpotassium, 2,5-decadienylrubidium, 4,6-di-n-butyldecylsodium, phenyl-potassium, benzylsodium and 4-tolylpotassium.
Alkali metal compounds having the formula RZOM which may be used are alkali metal salts of mono- and polyhydric alcohols and phenols such as sodium, potassium, rubidium or caesium salts of methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, t-butyl alcohol, t-amyl alcohol, n-hexyl alcohol, cyclohexylalcohol, 2-butenyl alcohol, 4-methylcyclohexenyl alcohol, 3-cyclo-pentenyl alcohol, 3-hexenylalcohol, 2,5-decadienyl alcohol, allyl alcohol, 1,3-dihydrohexane, 1,5,9-trihydroxytridecane, benzyl alcohol, phenol, catechol, Le A 33 727-Foreign Countries resorcinol, hydroquinone, pyrogallol, 1-naphthol, 2-naphthol, 2,6-di-t-butyl-4-methylphenol, 2,4,5,6-tri-t-butylphenol, n-nonylphenol and 1,12-dodecane diol.
Alkali metal compounds having the formula R3COOM which may be used are alkali metal salts of mono- or polyvalent carboxylic acids such as sodium, potassium, rubidium or caesium salts of lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, sebacic acid, phthalic acid and 1,8,16-hexadecanetoloyl carboxylic acid.
Alkali metal compounds having the formula R4RSNM which may be used are alkali metal salts of secondary amines such as sodium, potassium, rubidium or caesium salts of dimethylamine, di-n-butylamine, methyl-n-hexylamine, di-(3-hexenyl)amine, diphenylamine and dibenzylamine.
Alkali metal-containing alcoholates are used in preference in the process according to the present invention, such as sodium, potassium, rubidium or caesium salts of methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, tert.-butyl alcohol, tert.-amyl alcohol, n-hexyl alcohol, cyclohexylalcohol, butyl alcohol, phenol and 1-naphthol. More particularly preferably, the potassium salt of tert.-amyl alcohol is used.
The alkali metal compounds are normally used in the process according to the present invention in an amount such that the molar ratio of lithium metal-containing initiator to alkali metal compounds is 1 : 0.005 to 1 : 0.25.
Of course, it is also possible to carry out the process according to the invention in the presence of so-called modifiers such as ethers and/or amine compounds such as tertiary amines, which are capable of controlling the vinyl content in the polymer chain. More particularly, ether compounds and amine compounds which may be mentioned include triethylamine, pyridine, tetramethylethylene diamine (TMEDA), tetrahydrofuran (THF), diethylether, diphenylether, anisole, ethylene glycol Le A 33 727-Foreign Countries dimethylether, ethylene glycol diethylether, ethylene glycol ethyl-tert.-butyl ether, 2,2-bis-(2-oxolanyl)propane, and oligomeric oxolanyl alkanes. The modifiers mentioned may be used both individually and in mixture.
The optimum amount of modifiers to be used may be determined easily by appropriate preliminary tests and depends on the desired vinyl group content in the polymer chain. Amounts from about 0.005 to 400 mmole per 100 g of monomers used are customary.
The process according to the present invention may be earned out at temperatures from about 40°C to 160°C, preferably 50°C to 130°C. The process according to the present invention may be carried out at a pressure below atmospheric, at normal pressure and at elevated pressure, preferably at elevated pressure, for example, at pressures from 1 to 10 bar.
The process according to the present invention may be carried out both continuously and batchwise.
The process according to the present invention is earned out in the presence of the conventional inert solvents which are well known for anionic polymerization.
These are, more particularly, aromatic and/or aliphatic hydrocarbons with 2 to 12 carbon atoms, such as ethane, propane, iso- and n-butane, iso- and n-pentane, iso-and n-hexane, iso- and n-heptane, iso- and n-octane, cyclobutane, cyclopentane, cyclo-hexane, cycloheptane, cyclooctane, where n-hexane and cyclohexane are preferable.
The solvents may be used both individually and in mixture, and of course in the form of their isomer mixtures.
The most favourable amount of solvent in each case may also be determined easily by appropriate preliminary tests.
Le A 33 727-Foreign Countries _7_ The copolymers prepared according to the present invention based on aromatic vinyl compounds and conjugated dimes are suitable for the manufacture of vulcanizates which have outstanding damping behavior coupled with superior wet skid behavior, which is why the copolymers prepared according to the present invention are S particularly suitable for the manufacture of tires, preferably tire treads.
Of course, other vulcanized molded articles in which the above-mentioned physical properties are of importance may be manufactured from the copolymers according to the present invention.
EXAMPLES
The polymerization reactions were carried out under nitrogen with the exclusion of air and moisture.
The determination of the styrene content in the polymer and of the selectivity of polybutadiene (1,4-cis, 1,4-trans and 1,2-content) is carried out by IR
spectroscopy, the damping behavior and the determination of the half width of the loss factor by frequency-dependent measurements of complex material quantities.
Examples 1 to 4 Polymerization Polymerization was earned out in a 2 liter Buchi glass autoclave with stirrer and jacket heating. The amounts of styrene, 1,3-butadiene, hexane (mixture of isomers), initiator solution (n-butyllithium in n-hexane), alkali metal alcoholate potassium-tert.-amylate (KTA) and modifier diethoxyethane (DEE) given in Table 1 were added under nitrogen. The temperature was set at 60°C. After complete conversion had been achieved (about 2 h), the polymer was isolated by precipitation of the polymer solution in ethanolBHT (2,6-di-tert.-butyl-4-methylphenol) and dried at 60°C in a Le A 33 727-Foreign Countries _g_ vacuum drying oven until a constant weight was obtained. The batch sizes, reaction conditions and the properties of the polymers obtained are given in Table 1.
Table 1: Examples 1 to 4 S
Example 1 2 3 4 Polymerization BuLi in mmole 1.13 1.13 1.13 1.13 Hexane in g 850 850 850 850 Styrene in g 37.5 37.5 37.5 37.5 1,3-butadiene in g 112.5 112.5 112.5 112.5 KTA in mmole 0 0.023 0.057 0.283 DEE in mmole 1.75 1.75 1.75 1.75 Polymer Styrene content in wt.% 23.1 23.8 23.7 23.9 Butadiene content in 76.9 76.2 76.3 76.1 wt.%
cis in % 12.3 12.0 12.4 16.0 trans in % 18.3 17.2 17.5 24.4 1,2- in % 46.3 47.0 46.4 35.7 Half width in log (f/Hz)4.4 3 3 6.3 Frequency position in 5.3 4.4 4.7 -0.6/9.8 log (f/Hz) Examples 5-8 Polymerization Polymerization was carried out in the same way as in Examples 1 to 4, but without the use of an ether. The quantities used, the reaction conditions and the properties of the resulting polymers are shown in Table 2.
Le A 33 727-Foreign Countries Table 2: Examples 5 to 8 Example 5 6 7 g Polymerization BuLi in mmoles 1.25 1.25 1.25 1.25 Hexane in g 850 850 850- 850 Styrene in g 37.5 37.5 37.5 37.5 1,3-butadiene in g 112.5 112.5 112.5 112.5 KTA in mmoles 0 0.063 0.125 0.25 Polymer Styrene content in wt.% 25.5 26.2 26.4 26.1 Butadiene content in 74.5 73.8 73.6 73.9 wt.%
cis in % 30.0 28.7 27.4 25.6 trans in % 37.4 35.9 34.4 32.4 1,2- in % 7.1 9.2 11.8 15.9 Half width in log (f/Hz)4.4 4.3 3.7 5.0 Frequency position in 6.9 6.5 6.0 ~ 5.6 log (f/Hz)
Claims (15)
1. A process for the preparation of copolymers based on vinyl aromatic compounds and conjugated dimes with an average molecular weight (Mn) from 50,000 to 600,000 g/mole, a vinyl aromatic compound content from 5 to 50 wt.%, and a conjugated dime content from 50 to 95 wt.%, comprising the step of reacting a vinyl aromatic compound with a conjugated diene in the presence of a lithium metal-containing initiator, wherein polymerization is controlled such that the damping in the glass process comprises a frequency range wherein the half-width of the maximum of the loss factor tan 8 is greater than 3 frequency decades.
2. A process according to Claim 1, wherein said lithium metal-containing initiators are used in amounts from 0.1 to 15 mmole, based on 100 g of polymer.
3. A process according to Claim 1, wherein said lithium metal-containing initiators are used in amounts from 0.2 to 10 mmole, based on 100 g of polymer.
4. A process according to Claim 1, wherein said damping in the glass process comprises a frequency range wherein the half-width of the maximum of the loss factor tan .delta. is 3.5 to 6 frequency decades.
5. A process according to Claim 1, wherein said damping in the glass process comprises a frequency range wherein the half-width of the maximum of the loss factor tan .delta. is 4 to 6 frequency decades.
6. A process according to Claim 1, wherein the copolymers have an average molecular weight (Mn) from 100,000 to 500,000 g/mole.
7. A process according to Claim 1, wherein the vinyl aromatic compound content is in the range from 10 to 45 wt.%.
8. A process according to Claim 1, wherein the conjugated diene content is in the range from 55 to 90 wt.%.
9. A process according to Claim 1, wherein said polymerization is carried out at temperatures from 40°C to 160°C.
10. A process according to Claim 1, wherein said polymerization is carried out at temperatures from 50°C to 130°C.
11. A process according to Claim 1, wherein said polymerization is carried out in the presence of an inert solvent.
12. A process according to Claim 1, wherein said polymerization is carried out in the presence of alkali metal compounds.
13. A process according to Claim 12, wherein the alkali metal compounds are of the following general formulae: R1M, R2OM, R3COOM and R4R5NM, wherein R1, R2, R3, R4 and R5 is an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or a partially substituted group thereof, and M is Na, K, Rb or Cs.
14. A process according to Claim 12, wherein the molar ratio of alkali-metal compounds to lithium metal-containing initiator is 0.005:1.
15. A process according to Claim 12, wherein the molar ratio of alkali-metal compounds to lithium metal-containing initiator is 0.25:1.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19941314.2 | 1999-08-31 | ||
| DE1999141314 DE19941314A1 (en) | 1999-08-31 | 1999-08-31 | Process for the preparation of a copolymer based on vinyl aromatic compounds and conjugated dienes and its use for the production of vulcanizates with excellent damping behavior |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2316770A1 true CA2316770A1 (en) | 2001-02-28 |
Family
ID=7920220
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2316770 Abandoned CA2316770A1 (en) | 1999-08-31 | 2000-08-28 | A process for the preparation of a copolymer based on vinyl aromatic compounds and conjugated dienes and the use thereof for the manufacture of vulcanizates with outstanding damping behavior |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP1081168A3 (en) |
| JP (1) | JP2001089540A (en) |
| CA (1) | CA2316770A1 (en) |
| DE (1) | DE19941314A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7151147B2 (en) | 2002-07-30 | 2006-12-19 | Sasol Germany Gmbh | Method for producing polymers using conjugated dienes and vinyl aromatic compounds, polymers produced according to said method and use thereof |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10240790B3 (en) * | 2002-08-30 | 2004-04-22 | Sasol Germany Gmbh | A process for preparation of polymerisates using conjugated dienes and vinyl aromatic compounds useful in the production or use of damping materials and/or tires, especially winter, slush, and snow tires, preferably ire treads |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3319639B2 (en) * | 1992-12-24 | 2002-09-03 | 株式会社ブリヂストン | Method for producing conjugated diene polymer, styrene-butadiene polymer and rubber composition thereof |
| EP0798339B1 (en) * | 1996-03-29 | 2002-06-05 | Bridgestone Corporation | Styrene-butadiene copolymer and rubber composition comprising the copolymer |
-
1999
- 1999-08-31 DE DE1999141314 patent/DE19941314A1/en not_active Withdrawn
-
2000
- 2000-08-18 EP EP00117296A patent/EP1081168A3/en not_active Withdrawn
- 2000-08-28 JP JP2000257449A patent/JP2001089540A/en active Pending
- 2000-08-28 CA CA 2316770 patent/CA2316770A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7151147B2 (en) | 2002-07-30 | 2006-12-19 | Sasol Germany Gmbh | Method for producing polymers using conjugated dienes and vinyl aromatic compounds, polymers produced according to said method and use thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| DE19941314A1 (en) | 2001-03-01 |
| JP2001089540A (en) | 2001-04-03 |
| EP1081168A2 (en) | 2001-03-07 |
| EP1081168A3 (en) | 2004-01-02 |
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