CA1067643A - Preparation of a non-linear, elastomeric copolymer - Google Patents
Preparation of a non-linear, elastomeric copolymerInfo
- Publication number
- CA1067643A CA1067643A CA237,975A CA237975A CA1067643A CA 1067643 A CA1067643 A CA 1067643A CA 237975 A CA237975 A CA 237975A CA 1067643 A CA1067643 A CA 1067643A
- Authority
- CA
- Canada
- Prior art keywords
- block
- monoalkenyl
- polymer
- aromatic hydrocarbon
- conjugated diene
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G81/00—Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers
- C08G81/02—Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers at least one of the polymers being obtained by reactions involving only carbon-to-carbon unsaturated bonds
- C08G81/021—Block or graft polymers containing only sequences of polymers of C08C or C08F
- C08G81/022—Block or graft polymers containing only sequences of polymers of C08C or C08F containing sequences of polymers of conjugated dienes and of polymers of alkenyl aromatic compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G81/00—Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers
- C08G81/02—Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers at least one of the polymers being obtained by reactions involving only carbon-to-carbon unsaturated bonds
- C08G81/021—Block or graft polymers containing only sequences of polymers of C08C or C08F
Abstract
ABSTRACT OF THE DISCLOSURE
Non-linear, solution diene rubbers, e.g. SBR, obtain improved green strength, if less than 30% of the polymer chains is "capped" with a polystyrene block having a mol. weight of, e.g., 20,000. They are obtained by coupling polymer blocks B'-Li and A-B-Li in a molar ratio of at least 2.5 with an at least trifunctional coupling agent, wherein A is a polymer block of a monoalkenyl or monoalkenylidene aromatic hydrocarbon having an average molecular weight between 5,000 and 35,000, B and B' are polymer blocks substantially comprising polymerized con-jugated diene molecules. These rubbers exhibit an improved green strength whilst retaining adequate processability and satisfactory properties after vulcanization.
Non-linear, solution diene rubbers, e.g. SBR, obtain improved green strength, if less than 30% of the polymer chains is "capped" with a polystyrene block having a mol. weight of, e.g., 20,000. They are obtained by coupling polymer blocks B'-Li and A-B-Li in a molar ratio of at least 2.5 with an at least trifunctional coupling agent, wherein A is a polymer block of a monoalkenyl or monoalkenylidene aromatic hydrocarbon having an average molecular weight between 5,000 and 35,000, B and B' are polymer blocks substantially comprising polymerized con-jugated diene molecules. These rubbers exhibit an improved green strength whilst retaining adequate processability and satisfactory properties after vulcanization.
Description
The invention relates to a process for the preparation of a non-linear, elastomeric copolymer, to the copolymer thus prepared and to articles manufactured from such a copolymer.
One of the major deficiencies of commerclally available, solution-polymerized, anionically~initiated synthetic rubbers such as butadiene polymers and styrene/
butadiene copolymers, is the poor properties of the uncured black stocks. In particular,the tack and green ; 10 strength are seriously deficient compared with, e.g., . emulsion styrene/butadiene copolymers, which leads to difficulties in factory processing. By green strength is meant the strength of the rubber or compound thereof which has not been vulcanized.
It is an object of the present invention to provide conjugated diene elastomers exhibiting improved green strength while still having an adequate processability and satisfactory properties of the vulcanized compound.
According to the present invention a process is provided for the preparation of a non-linear, elastomeric copolymer, which process comprises:
(a) polymerizing a conjugated diene in the presence , ~
~i of a monolithium-terminated polymer of a monoalkenyl , ;,. ~
or monoalkenylidene aromatic hydrocarbon, A-Li, in which A indicates a polymer block of a monoalkenyl or monoalkenylidene aromatic hydrocarbon, having ;1 an average molecular weight between 5000 and 35000, . .
,: , ,.
'`' ~
~067643 so as to fo~m a block co-polymer A-B-Li, in which block B substantially comprises polymerized, con~ugated diene molecules and in which block A-B
has an LVN (limiting viscosity number) between 0.1 and 10 d Vg;
(b) polymerizing a con~ugated diene in the presence of an alkyllithium initiator, R-Li; R being an alkyl group, so as to form a polymer block B'-Li substantially comprising polymerized, con~ugated diene molecules, polymer block B' having an LVN between 0.1 and 10 dl/g, and the molar ratio X between the initiator R-Li and the compound A-Li being between 2.5:1 and 10:1;
(c) coupling the polymer blocks A-B-Li and B'-Li obtained by the polymerizations mentioned sub (a) and (b) with a coupling agent C which is at least trifunctional lnsofar as its coupling activity is concerned, the molar ratio of the sum of A-B-Li and BILi polymer blocks to coupling agent being from 3:1 to 5~
The products of the present invention are designed within specific limits in their constitution and proportion so as to obtain the ;
desired results, i.e. improved green strength, building tack, elongation as well as processability.
The con~ugated diene for ~he formation of the polymer blocks . ,.:, ; 20 B' and A-B may be isoprene or piperylene, but is preferably butadiene.
The aromatic hydrocarbon for the formation of the polymer block A is j preferably ", :
'~ :
....
~, .
;~ - 3 -., ' .
:-:
.
-styrene. The molecular weight of poly~er block ~ is suitably between 15,000 and 25,000 if the copolymer is to be used in non-oil-extended compounds, and between - 20,000 and 30,000 if the copolymer is to be used in oil-extended compounds. The blocks B' and B may - and preferably do - also contain a copolymerized monoalkenyl or monoalkenylidene aromatic hydrocarbon, in particular styrene in a minor amount. The amount o~ the aromatic hydrocarbon thus copolymerized in blocks B' and B, is suitably in the range of 10-30~ based on the weight of said blocks. Blocks B' and B may be of the same or different constitution, within the general limits specified above. The LVN of blocks A-B and B' is preferably ; between 0.2 and 3 dl/g.
i::: , .
The molecular weight of the A block and the LVN
of the A-B and B' blocks are determined - after killing the A-Li, A-B-Li and B'-Li blocks, e.g. with methanol and dissolving them in a suitable solvent - by methods , -. , ~
known in the art. Thus the molecular weight of the A block may be determined by gel permeation chromatography : .' ~ after calibration with polystyrene of known molecular ., ~` weight. The LVN is determined in toluene at 30C. The total styrene of the copolymer is determined by infrared ~`l analysis.
The polymer blocks A-B-Li and B~-Li are prepared ::
by solution polymerization utilizing the compounds A-Li and R-Li, respectively, as initiators. The alkyl ,,','' t l '. ' ', '' ' ' :
~67643 group R pre~erably contains from 3 to 9 carbon atoms, in particular from 3 to 6 carbon atoms. Isopropyllithium and secondary butyllithium are especially preferred.
The compound A-Li, used as the other initiator, may be prepared by polymerization of a monoalkenyl or monoalkenylidene aromatic hydrocarbon in solution in the presence of an alkyl lithium, R Li, as described.
If the desired (number average) molecular weight of the block A is denoted: Ms; the grammolar amount of initiator: (R-Li); and the weight in grams of the monoalkenyl or monoalkeny]ider.earomatic hydrocarbon:
, .
~ (Ar), then the following function exists:
~``.` 1 :
, Ms = (Ar~/(R-Li). This will serve to calculate the amounts of aromatic hydrocarbon and alkyllithium required , 15 to obtain a block A-Li of the desired molecular weight.
Monomers to be polymerized, the conjugated diene, and, if desired the monovinylarene, are dissolved in ' a substantially inert solvent such as alkenes, alkanes : and cycloalkanes. Suitable species of these include pentane, cyclopentane, hexane, cyclohexane, and mixtures ~ of the same. The polymerization reactions (a) and (b) s as well as the coupling reaction (c) may be carried :,: ~
l out at 20C-150C, preferably at 45Oc-gooc, for 15 , , .
;^ minutes to 8 hours, in an inert atmosphere such as under nitrogen. The concentration of the monomers in the reactor is not critical, and is mainly chosen on .
~ the basis of the ultimate, practically feasible viscosity ''"' ,:', ', ' .
, :
o~ the elastomer solution, solutions of 20% solids content being still stirrable.
The polymerizations may be carried out in the presence of polar compounds such as ethers, amines and other Lewis bases so as to obtain diene blocks ha~ing an increased (e.g. 30-~0%) vinyl content.
Although the polymerizations according to the invention may be carried out continuously, it is usually more advantageous to effect these batchwise. A preferred method for the copolymerization of a conjugated diene with a minor amount of a monoalkenyl or monoalkenylidene aromatic hydrocarbon so as to prepare the polymer blocks . B and B', has been set out in British patent specification 1,283,327. According to this method, first a starting mixture is prepared from the diluent and a part - preferably less than 50 %w - of the totally needed quantity of each of the monomers; subsequently initiating the mixture by addition of the initiator R-Li or A-Li~ and keeping the monomer ratio in the reaction mixture during copolymerization substantially constant by addition of the remaining part of each of the monomers. By "substantially constant"
is meant that the monomer weight ratio during the copolymerization .: ~
should increase or decrease by not more than 20%.
The two types of polymerizations, (a) and (b) ,: ~
j 25 may be carried out separately or in the same reactor.
:. ' In this connection the following options exist, among - others:
.. .
.
.
' '.'' , (1) the cQnjugated diene, lf desired in the presence of the monoalkenyl or monoalkenylidene aromatic hydrocarbon, is polymerized in separate reactors in the presence of compounds A~Li and R-Li, so as to form the polymer blocks A-B-Li and B'-Li, ; respectively. The blocks B and B' may be of the - same or a different composition, within the limits specified above;
One of the major deficiencies of commerclally available, solution-polymerized, anionically~initiated synthetic rubbers such as butadiene polymers and styrene/
butadiene copolymers, is the poor properties of the uncured black stocks. In particular,the tack and green ; 10 strength are seriously deficient compared with, e.g., . emulsion styrene/butadiene copolymers, which leads to difficulties in factory processing. By green strength is meant the strength of the rubber or compound thereof which has not been vulcanized.
It is an object of the present invention to provide conjugated diene elastomers exhibiting improved green strength while still having an adequate processability and satisfactory properties of the vulcanized compound.
According to the present invention a process is provided for the preparation of a non-linear, elastomeric copolymer, which process comprises:
(a) polymerizing a conjugated diene in the presence , ~
~i of a monolithium-terminated polymer of a monoalkenyl , ;,. ~
or monoalkenylidene aromatic hydrocarbon, A-Li, in which A indicates a polymer block of a monoalkenyl or monoalkenylidene aromatic hydrocarbon, having ;1 an average molecular weight between 5000 and 35000, . .
,: , ,.
'`' ~
~067643 so as to fo~m a block co-polymer A-B-Li, in which block B substantially comprises polymerized, con~ugated diene molecules and in which block A-B
has an LVN (limiting viscosity number) between 0.1 and 10 d Vg;
(b) polymerizing a con~ugated diene in the presence of an alkyllithium initiator, R-Li; R being an alkyl group, so as to form a polymer block B'-Li substantially comprising polymerized, con~ugated diene molecules, polymer block B' having an LVN between 0.1 and 10 dl/g, and the molar ratio X between the initiator R-Li and the compound A-Li being between 2.5:1 and 10:1;
(c) coupling the polymer blocks A-B-Li and B'-Li obtained by the polymerizations mentioned sub (a) and (b) with a coupling agent C which is at least trifunctional lnsofar as its coupling activity is concerned, the molar ratio of the sum of A-B-Li and BILi polymer blocks to coupling agent being from 3:1 to 5~
The products of the present invention are designed within specific limits in their constitution and proportion so as to obtain the ;
desired results, i.e. improved green strength, building tack, elongation as well as processability.
The con~ugated diene for ~he formation of the polymer blocks . ,.:, ; 20 B' and A-B may be isoprene or piperylene, but is preferably butadiene.
The aromatic hydrocarbon for the formation of the polymer block A is j preferably ", :
'~ :
....
~, .
;~ - 3 -., ' .
:-:
.
-styrene. The molecular weight of poly~er block ~ is suitably between 15,000 and 25,000 if the copolymer is to be used in non-oil-extended compounds, and between - 20,000 and 30,000 if the copolymer is to be used in oil-extended compounds. The blocks B' and B may - and preferably do - also contain a copolymerized monoalkenyl or monoalkenylidene aromatic hydrocarbon, in particular styrene in a minor amount. The amount o~ the aromatic hydrocarbon thus copolymerized in blocks B' and B, is suitably in the range of 10-30~ based on the weight of said blocks. Blocks B' and B may be of the same or different constitution, within the general limits specified above. The LVN of blocks A-B and B' is preferably ; between 0.2 and 3 dl/g.
i::: , .
The molecular weight of the A block and the LVN
of the A-B and B' blocks are determined - after killing the A-Li, A-B-Li and B'-Li blocks, e.g. with methanol and dissolving them in a suitable solvent - by methods , -. , ~
known in the art. Thus the molecular weight of the A block may be determined by gel permeation chromatography : .' ~ after calibration with polystyrene of known molecular ., ~` weight. The LVN is determined in toluene at 30C. The total styrene of the copolymer is determined by infrared ~`l analysis.
The polymer blocks A-B-Li and B~-Li are prepared ::
by solution polymerization utilizing the compounds A-Li and R-Li, respectively, as initiators. The alkyl ,,','' t l '. ' ', '' ' ' :
~67643 group R pre~erably contains from 3 to 9 carbon atoms, in particular from 3 to 6 carbon atoms. Isopropyllithium and secondary butyllithium are especially preferred.
The compound A-Li, used as the other initiator, may be prepared by polymerization of a monoalkenyl or monoalkenylidene aromatic hydrocarbon in solution in the presence of an alkyl lithium, R Li, as described.
If the desired (number average) molecular weight of the block A is denoted: Ms; the grammolar amount of initiator: (R-Li); and the weight in grams of the monoalkenyl or monoalkeny]ider.earomatic hydrocarbon:
, .
~ (Ar), then the following function exists:
~``.` 1 :
, Ms = (Ar~/(R-Li). This will serve to calculate the amounts of aromatic hydrocarbon and alkyllithium required , 15 to obtain a block A-Li of the desired molecular weight.
Monomers to be polymerized, the conjugated diene, and, if desired the monovinylarene, are dissolved in ' a substantially inert solvent such as alkenes, alkanes : and cycloalkanes. Suitable species of these include pentane, cyclopentane, hexane, cyclohexane, and mixtures ~ of the same. The polymerization reactions (a) and (b) s as well as the coupling reaction (c) may be carried :,: ~
l out at 20C-150C, preferably at 45Oc-gooc, for 15 , , .
;^ minutes to 8 hours, in an inert atmosphere such as under nitrogen. The concentration of the monomers in the reactor is not critical, and is mainly chosen on .
~ the basis of the ultimate, practically feasible viscosity ''"' ,:', ', ' .
, :
o~ the elastomer solution, solutions of 20% solids content being still stirrable.
The polymerizations may be carried out in the presence of polar compounds such as ethers, amines and other Lewis bases so as to obtain diene blocks ha~ing an increased (e.g. 30-~0%) vinyl content.
Although the polymerizations according to the invention may be carried out continuously, it is usually more advantageous to effect these batchwise. A preferred method for the copolymerization of a conjugated diene with a minor amount of a monoalkenyl or monoalkenylidene aromatic hydrocarbon so as to prepare the polymer blocks . B and B', has been set out in British patent specification 1,283,327. According to this method, first a starting mixture is prepared from the diluent and a part - preferably less than 50 %w - of the totally needed quantity of each of the monomers; subsequently initiating the mixture by addition of the initiator R-Li or A-Li~ and keeping the monomer ratio in the reaction mixture during copolymerization substantially constant by addition of the remaining part of each of the monomers. By "substantially constant"
is meant that the monomer weight ratio during the copolymerization .: ~
should increase or decrease by not more than 20%.
The two types of polymerizations, (a) and (b) ,: ~
j 25 may be carried out separately or in the same reactor.
:. ' In this connection the following options exist, among - others:
.. .
.
.
' '.'' , (1) the cQnjugated diene, lf desired in the presence of the monoalkenyl or monoalkenylidene aromatic hydrocarbon, is polymerized in separate reactors in the presence of compounds A~Li and R-Li, so as to form the polymer blocks A-B-Li and B'-Li, ; respectively. The blocks B and B' may be of the - same or a different composition, within the limits specified above;
(2) the compound A-Li is first prepared in the diluent by polymerizing the monoalkenyl or monoalkenylidene aromatic hydrocarbon in the presence of an amount, p, of initiator R-Li. After completion of this j .
i polymerization the conjugated diene, if desired the aromatic hydrocarbon as comonomer, and a further amount, q, of the same or a different initiator i R-Li are added to compound A-Li, formed in the , diluent. The amounts of initiator R-Li employed are such that the molar ratio of q/p is at least 2.5. In general, this molar ratio q/p will equal ., .~
~ 20 the ratio X. This second method is the preferred .. ~
~;~ method~
Suitably the molar ratio X between R-Li and A-Li is between 2.5 and 10. For use in oil-extended compounds, i.e. in compounds containing 10-100 phr (parts by weight 1~ 25 per 100 parts of the non-linear, elastomeric copolymer) of an extender oil, the preferred ratio X or q/p is `l between 2.6 and 4.5. For use of the copolymer in non-oil-:.:
''''~' " :, , :
~067643 extended compounds - containing less than 10 phr of oil - the preferred ratio X or q/p is between 3 and 6.
If they have been prepared separately, the solutions of the active polymer blocks A-B-Li and B'~Li are mixed.
If prepared according to the above preferred second method, these blocks are already available as a mixture, of course. The mixture is coupled by contactin~ it with the coupling agent C.
The preferred type of coupling agent is a tetrafunctional - ester derived from a dicarboxylic acid and a monohydric alcohol. Dimethyl adipate and diethyl adipate are especially suitable for this purpose. Usually these diesters will be used in an about equivalent ratio, i.e. in a molar ratio of (A-B-Li + B'-Li) blocks to diester between
i polymerization the conjugated diene, if desired the aromatic hydrocarbon as comonomer, and a further amount, q, of the same or a different initiator i R-Li are added to compound A-Li, formed in the , diluent. The amounts of initiator R-Li employed are such that the molar ratio of q/p is at least 2.5. In general, this molar ratio q/p will equal ., .~
~ 20 the ratio X. This second method is the preferred .. ~
~;~ method~
Suitably the molar ratio X between R-Li and A-Li is between 2.5 and 10. For use in oil-extended compounds, i.e. in compounds containing 10-100 phr (parts by weight 1~ 25 per 100 parts of the non-linear, elastomeric copolymer) of an extender oil, the preferred ratio X or q/p is `l between 2.6 and 4.5. For use of the copolymer in non-oil-:.:
''''~' " :, , :
~067643 extended compounds - containing less than 10 phr of oil - the preferred ratio X or q/p is between 3 and 6.
If they have been prepared separately, the solutions of the active polymer blocks A-B-Li and B'~Li are mixed.
If prepared according to the above preferred second method, these blocks are already available as a mixture, of course. The mixture is coupled by contactin~ it with the coupling agent C.
The preferred type of coupling agent is a tetrafunctional - ester derived from a dicarboxylic acid and a monohydric alcohol. Dimethyl adipate and diethyl adipate are especially suitable for this purpose. Usually these diesters will be used in an about equivalent ratio, i.e. in a molar ratio of (A-B-Li + B'-Li) blocks to diester between
3:1 and 5:1, the equivalent ratio being 4:1.
A number of other polyfunctional coupling agents ~- may be employed in addition to or in place of the preferred diesters. ~hese include polyepoxides, polyisocyanates, polyamines, polyaldehydes, polyanhydrides, polyesters and polyhalides, such as tribromobutane, tin tetrachloride and silicon tetrachloride. Other useful types of coupling agents are alpha-beta-olefinically unsaturated nitriles, in particular acrylonitrile, and certain unsaturated halides such as vinyl chloride, 1-chloro-1,3-butadiene, p-halostyrene and 2-chloro-1-propene. The unsaturated nitriles and halides are generally used in an amount .
l. .j . . , ': ~
. ' ........ ...
iO67643 g of 0.1-1.5% based on the sum of the weight of the A-B-Li and B'/Li blocks, so as to provide a molar ratio of nitrile or halide to the sum of A-B-Li plus B'/Li of - approximately 3-15. It is assumed that under the conditions of the coupling reaction the unsaturated nitrile or halide forms small, polyfunctional end blocks on a part of the A-B- or B'-blocks. Via the pendent nitrile groups or halide atoms the remaining A-B-Li and B'-Li blocks , add to form the non-linear, elastomeric copolymers.
10Subsequent to the coupling operation, the product may be hydrogenated though, of course, in applications involving vulcanisation with sulphur, such hydrogenation ~' is undesirable.
EXAMPLES
' l 15The polymerizations were carried out at 750C
in a 10 litre autoclave charged with 8 1 of a 50/50 w/w mixture of cyclohexane and n-hexane. Next an amount ', i of styrene, indicated in the Table, was added and the mixture titrated at room temperature with a 12 %w solution of secondary butyllithium (BuLi) in cyclohexane to incipient polymerization, indicated by a temperature i rise of 0.1C. Thereby any impurities present in the ;i,~ `.
solvent mixtures were scavenged. Thereafter, the temperature was raised to and maintained at 75C, and a further :: j amount of the solution, containing the amount of butyllithium ~ indicated in the Table, was added. After 15 minutes ..... .
the block A-Li had been formed. Subsequently an initial 3l~
. ~
,:;.~^.
, . .
,, ., ~, . ., ,,,.~ . . . . .
;;,. - . :
~067643 ~ -- 10 --~ mixture of styrene/butadiene was added, as indicated i in the Table, together with the amount of butyllithium indicated. After these additions, a feed mixture of styrene and butadiene - as indicated in the Table -., .
was added at a constant rate over a period of 3 hours.
, At the end of the polymerization the amount of DEAP
(diethyl adipate) indicated was added at 75C. After about 2 hours 10 grams of 2,6-ditert.butyl-4-methylphenol ' was added after which the solvent was removed by steam stripping. The polymer obtained was dried in an oven at 90C. The results appear from the following Table.
In the calculation of molar ratio X between the initiator ~-~ Bu-Li, added after the A-Li formation, and the Bu-Li, used in the A-Li formation - disregarding the Bu-Li ~ , 15 used for scavenging the solvent mixture -, it is assumed ,;~ that the total amount of Bu-Li used in the A-Li formation , , .
, will be available as living A-Li blocks.
Black stocks were prepared according to the following recipe:
Copolymer . . . . . . . . . . . . . 100 parts by weight ~;~ ZnO .............................. 5 " " "
Stearic acid. . . . . . . . . . . . 3 " " "
N-(1,3-dimethylbutyl)-N'-phenyl-p-;- phenylenediamine . . . . . . . . 1.5 parts-by weight ,.. . .
'~, N,N'-bis(1,4-dimethylpentyl)-p-~ ~ 25 phenylenediamine . . . . . . . 1 5 " " "
~:;
~` Paraffin wax. . . . . . . . . . . . 1 " " "
~ ' .
:
~: , '';
:.:
'; ~
~ ' :,.
.
~067643 Aromatic extender oil,"DUTREX"729/HP 5 parts by weig~t ISAF carbon black . . . . . . ~ . . 50 " " "
Sulphur . . . . . . . . . . . . . . 2 " " "
N-cyclohexyl-2-benzothiazolsulphen-amide. . . . . . . . . . . . . 1 " " "
The same recipe was used for the "oil-extended"
composition, containing 37.5 parts by weight of aromatic extender oil, "DUTREX"729HP, except for the following modifications:
Sulphur . . . . . . . . . . . . . . 1.85 parts by weight -N-cyclohexyl-2-benzothiazolsulphen-amide. . . . . . . . . . . . . o.8 ,':
. .
'.....
.,:
:
, .,.
.::
`' ,: . , .. . .
,:
,. . .
:
' ~
. , .
'''~
, ~ .
From the data in the Table it follows that only copolymers having a ratio X o~ at least 2.5 possess a 100C-Mooney value wit~.in commercially acceptable limits of 40 to 100 in addition to improved green strength.
At very high ratios of X the green strength values, i.e. the tensile strength and elongation of the black stock, are undesirably low.
A number of other polyfunctional coupling agents ~- may be employed in addition to or in place of the preferred diesters. ~hese include polyepoxides, polyisocyanates, polyamines, polyaldehydes, polyanhydrides, polyesters and polyhalides, such as tribromobutane, tin tetrachloride and silicon tetrachloride. Other useful types of coupling agents are alpha-beta-olefinically unsaturated nitriles, in particular acrylonitrile, and certain unsaturated halides such as vinyl chloride, 1-chloro-1,3-butadiene, p-halostyrene and 2-chloro-1-propene. The unsaturated nitriles and halides are generally used in an amount .
l. .j . . , ': ~
. ' ........ ...
iO67643 g of 0.1-1.5% based on the sum of the weight of the A-B-Li and B'/Li blocks, so as to provide a molar ratio of nitrile or halide to the sum of A-B-Li plus B'/Li of - approximately 3-15. It is assumed that under the conditions of the coupling reaction the unsaturated nitrile or halide forms small, polyfunctional end blocks on a part of the A-B- or B'-blocks. Via the pendent nitrile groups or halide atoms the remaining A-B-Li and B'-Li blocks , add to form the non-linear, elastomeric copolymers.
10Subsequent to the coupling operation, the product may be hydrogenated though, of course, in applications involving vulcanisation with sulphur, such hydrogenation ~' is undesirable.
EXAMPLES
' l 15The polymerizations were carried out at 750C
in a 10 litre autoclave charged with 8 1 of a 50/50 w/w mixture of cyclohexane and n-hexane. Next an amount ', i of styrene, indicated in the Table, was added and the mixture titrated at room temperature with a 12 %w solution of secondary butyllithium (BuLi) in cyclohexane to incipient polymerization, indicated by a temperature i rise of 0.1C. Thereby any impurities present in the ;i,~ `.
solvent mixtures were scavenged. Thereafter, the temperature was raised to and maintained at 75C, and a further :: j amount of the solution, containing the amount of butyllithium ~ indicated in the Table, was added. After 15 minutes ..... .
the block A-Li had been formed. Subsequently an initial 3l~
. ~
,:;.~^.
, . .
,, ., ~, . ., ,,,.~ . . . . .
;;,. - . :
~067643 ~ -- 10 --~ mixture of styrene/butadiene was added, as indicated i in the Table, together with the amount of butyllithium indicated. After these additions, a feed mixture of styrene and butadiene - as indicated in the Table -., .
was added at a constant rate over a period of 3 hours.
, At the end of the polymerization the amount of DEAP
(diethyl adipate) indicated was added at 75C. After about 2 hours 10 grams of 2,6-ditert.butyl-4-methylphenol ' was added after which the solvent was removed by steam stripping. The polymer obtained was dried in an oven at 90C. The results appear from the following Table.
In the calculation of molar ratio X between the initiator ~-~ Bu-Li, added after the A-Li formation, and the Bu-Li, used in the A-Li formation - disregarding the Bu-Li ~ , 15 used for scavenging the solvent mixture -, it is assumed ,;~ that the total amount of Bu-Li used in the A-Li formation , , .
, will be available as living A-Li blocks.
Black stocks were prepared according to the following recipe:
Copolymer . . . . . . . . . . . . . 100 parts by weight ~;~ ZnO .............................. 5 " " "
Stearic acid. . . . . . . . . . . . 3 " " "
N-(1,3-dimethylbutyl)-N'-phenyl-p-;- phenylenediamine . . . . . . . . 1.5 parts-by weight ,.. . .
'~, N,N'-bis(1,4-dimethylpentyl)-p-~ ~ 25 phenylenediamine . . . . . . . 1 5 " " "
~:;
~` Paraffin wax. . . . . . . . . . . . 1 " " "
~ ' .
:
~: , '';
:.:
'; ~
~ ' :,.
.
~067643 Aromatic extender oil,"DUTREX"729/HP 5 parts by weig~t ISAF carbon black . . . . . . ~ . . 50 " " "
Sulphur . . . . . . . . . . . . . . 2 " " "
N-cyclohexyl-2-benzothiazolsulphen-amide. . . . . . . . . . . . . 1 " " "
The same recipe was used for the "oil-extended"
composition, containing 37.5 parts by weight of aromatic extender oil, "DUTREX"729HP, except for the following modifications:
Sulphur . . . . . . . . . . . . . . 1.85 parts by weight -N-cyclohexyl-2-benzothiazolsulphen-amide. . . . . . . . . . . . . o.8 ,':
. .
'.....
.,:
:
, .,.
.::
`' ,: . , .. . .
,:
,. . .
:
' ~
. , .
'''~
, ~ .
From the data in the Table it follows that only copolymers having a ratio X o~ at least 2.5 possess a 100C-Mooney value wit~.in commercially acceptable limits of 40 to 100 in addition to improved green strength.
At very high ratios of X the green strength values, i.e. the tensile strength and elongation of the black stock, are undesirably low.
Claims (20)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the preparation of a non-linear, elastomeric copolymer, which comprises:
(a) polymerizing a conjugated diene in the presence of a mono-lithium-terminated polymer of a monoalkenyl or monoalkenylidene aromatic hydrocarbon, A-Li, in which A indicates a polymer block of a monoalkenyl or monoalkenylidene aromatic hydrocarbon, having an average molecular weight between 5000 and 35000, so as to form a block copolymer A-B-Li, in which block B substantially comprises polymerized, conjugated diene molecules and in which block A-B has an LVN between 0.1 and 10 dl/g;
(b) polymerizing a conjugated diene in the presence of an alkyllithium initiator, R-Li, R being an alkyl group, so as to form a polymer block B'-Li substantially comprising polymerized, conjugated diene molecules, polymer block B' having an LVN between 0.1 and 10 dl/g, and the molar ratio X between the initiator R-Li and the compound A-Li being between 2.5:1 and 10:1;
(c) coupling the polymer blocks A-B-Li and B'-Li obtained by the polymerizations mentioned sub (a) and (b) with a coupling agent C
which is at least trifunctional insofar as its coupling activity is con-cerned, the molar ratio of the sum of A-B-Li and B-Li polymer blocks to coupling agent being from 3:1 to 5:1.
(a) polymerizing a conjugated diene in the presence of a mono-lithium-terminated polymer of a monoalkenyl or monoalkenylidene aromatic hydrocarbon, A-Li, in which A indicates a polymer block of a monoalkenyl or monoalkenylidene aromatic hydrocarbon, having an average molecular weight between 5000 and 35000, so as to form a block copolymer A-B-Li, in which block B substantially comprises polymerized, conjugated diene molecules and in which block A-B has an LVN between 0.1 and 10 dl/g;
(b) polymerizing a conjugated diene in the presence of an alkyllithium initiator, R-Li, R being an alkyl group, so as to form a polymer block B'-Li substantially comprising polymerized, conjugated diene molecules, polymer block B' having an LVN between 0.1 and 10 dl/g, and the molar ratio X between the initiator R-Li and the compound A-Li being between 2.5:1 and 10:1;
(c) coupling the polymer blocks A-B-Li and B'-Li obtained by the polymerizations mentioned sub (a) and (b) with a coupling agent C
which is at least trifunctional insofar as its coupling activity is con-cerned, the molar ratio of the sum of A-B-Li and B-Li polymer blocks to coupling agent being from 3:1 to 5:1.
2. A process as claimed in claim 1 in which the polymer block A
used has an average molecular weight between 15,000 and 30,000.
used has an average molecular weight between 15,000 and 30,000.
3. A process as claimed in claim 1 or 2 in which block A-B, or block B', or a mixture thereof, have an LVN between 0.2 and 3 dl/g.
4. A process as claimed in claim 1 in which A-Li is a polystyryl lithium compound, A being a polymerized styrene block.
5. A process as claimed in claim 1 in which the conjugated diene is butadiene.
6. A process as claimed in claim 1 in which the alkyl group R of the initiator R-Li used has 3 to 9 carbon atoms.
7. A process as claimed in claim 1 in which the polymerization reactions (a) and (b) and the coupling reaction (c) are carried out at a temperature of 20°C to 150°C.
8. A process as claimed in claim 7 in which said reactions are carried out at a temperature of 45°C to 90°C.
9. A process as claimed in claim 1 in which the polymer blocks B
and B' contain a minor amount of copolymerized monoalkenyl or monoalkenyl-idene aromatic hydrocarbon.
and B' contain a minor amount of copolymerized monoalkenyl or monoalkenyl-idene aromatic hydrocarbon.
10. A process as claimed in claim 9 in which the polymer blocks B
and B' contain a minor amount of styrene.
and B' contain a minor amount of styrene.
11. A process as claimed in claim 9 in which blocks B and B' con-tain 10-30% of copolymerized monoalkenyl or monoalkenylidene aromatic hydrocarbon, based on the weight of said blocks.
12. A process as claimed in any one of claims 9, 10 or 11, in which first a starting mixture is formed from a diluent and less than 50% w of the conjugated diene and the monoalkenyl or monoalkenylidene aromatic hydrocarbon, subsequently initiating the mixture by addition of the initiator R-Li or A-Li, and adding further amounts of each of the monomers, whilst increasing or decreasing the monomer ratio in the reaction mixture during the copolymerization by not more than 20%.
13. A process as claimed in claim 1 in which the compound A-Li is first prepared in a diluent by polymerizing the monoalkenyl or monoalkenyl-idene aromatic hydrocarbon in the presence of an amount, p, of the initiator R-Li, subsequently adding the conjugated diene and a further amount, q, of the initiator R-Li to compound A-Li formed in the diluent, R being an alkyl group and the molar ratio of q/p being at least 2.5, so as to form the mixture of polymer blocks A-B-Li and B'-Li.
14. A process as claimed in claim 13 in which the ratio q/p is between 2.5 and 10.
15. A process as claimed in claim 14 in which said ratio is between 3 and 6.
16. A process as claimed in claim 14 in which said ratio is between 2.6 and 4.5.
17. A process as claimed in claim 1 in which the coupling agent used is an ester derived from a dicarboxylic acid and a monohydric alcohol.
18. A process as claimed in claim 17 in which the ester used is diethyl adipate.
19. A non-linear, elastomeric copolymer, whenever obtained by a process as claimed in claim 1.
20. An article whenever manufactured from a copolymer as claimed in claim 19.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB52826/74A GB1527226A (en) | 1974-12-06 | 1974-12-06 | Preparation of a non-linear elastomeric copolymer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1067643A true CA1067643A (en) | 1979-12-04 |
Family
ID=10465474
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA237,975A Expired CA1067643A (en) | 1974-12-06 | 1975-10-20 | Preparation of a non-linear, elastomeric copolymer |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS5947687B2 (en) |
| AU (1) | AU500161B2 (en) |
| BE (1) | BE835943A (en) |
| CA (1) | CA1067643A (en) |
| DE (1) | DE2554585C2 (en) |
| ES (1) | ES443215A1 (en) |
| FR (1) | FR2293446A1 (en) |
| GB (1) | GB1527226A (en) |
| IT (1) | IT1051029B (en) |
| NL (1) | NL182571C (en) |
| ZA (1) | ZA757620B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2550226C2 (en) * | 1975-11-08 | 1984-12-13 | Basf Ag, 6700 Ludwigshafen | Branched block copolymers and process for their preparation |
| JPS61171714A (en) * | 1984-07-23 | 1986-08-02 | Japan Synthetic Rubber Co Ltd | Block copolymer and pressure-sensitive adhesive composition thereof |
| GB2169905A (en) * | 1984-12-13 | 1986-07-23 | Japan Synthetic Rubber Co Ltd | Conjugated diene based rubber composition |
| US5399627A (en) * | 1989-08-11 | 1995-03-21 | The Dow Chemical Company | Radial styrene-isoprene-butadiene multi-armed block copolymers and compositions and articles containing block copolymers |
| US5292819A (en) * | 1989-08-11 | 1994-03-08 | The Dow Chemical Company | Radial block copolymers containing butadiene endblock |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3639521A (en) * | 1969-04-23 | 1972-02-01 | Phillips Petroleum Co | Polar compound adjuvants for improved block polymers prepared with primary hydrocarbyllithium initiators |
-
1974
- 1974-12-06 GB GB52826/74A patent/GB1527226A/en not_active Expired
-
1975
- 1975-10-20 CA CA237,975A patent/CA1067643A/en not_active Expired
- 1975-11-26 BE BE1007032A patent/BE835943A/en not_active IP Right Cessation
- 1975-12-02 IT IT29939/75A patent/IT1051029B/en active
- 1975-12-04 ZA ZA757620A patent/ZA757620B/en unknown
- 1975-12-04 AU AU87267/75A patent/AU500161B2/en not_active Expired
- 1975-12-04 ES ES443215A patent/ES443215A1/en not_active Expired
- 1975-12-04 JP JP50143431A patent/JPS5947687B2/en not_active Expired
- 1975-12-04 DE DE2554585A patent/DE2554585C2/en not_active Expired
- 1975-12-04 NL NLAANVRAGE7514129,A patent/NL182571C/en active Search and Examination
- 1975-12-04 FR FR7537142A patent/FR2293446A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| IT1051029B (en) | 1981-04-21 |
| DE2554585C2 (en) | 1986-04-03 |
| BE835943A (en) | 1976-05-26 |
| FR2293446B1 (en) | 1980-06-20 |
| AU500161B2 (en) | 1979-05-10 |
| GB1527226A (en) | 1978-10-04 |
| JPS5947687B2 (en) | 1984-11-21 |
| AU8726775A (en) | 1977-06-09 |
| JPS5182390A (en) | 1976-07-19 |
| DE2554585A1 (en) | 1976-06-10 |
| NL182571C (en) | 1988-04-05 |
| ZA757620B (en) | 1976-11-24 |
| FR2293446A1 (en) | 1976-07-02 |
| ES443215A1 (en) | 1977-04-16 |
| NL7514129A (en) | 1976-06-09 |
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