CA1326722C - Elastomeric compositions, process for the preparation thereof and tyres containing them - Google Patents
Elastomeric compositions, process for the preparation thereof and tyres containing themInfo
- Publication number
- CA1326722C CA1326722C CA000579219A CA579219A CA1326722C CA 1326722 C CA1326722 C CA 1326722C CA 000579219 A CA000579219 A CA 000579219A CA 579219 A CA579219 A CA 579219A CA 1326722 C CA1326722 C CA 1326722C
- Authority
- CA
- Canada
- Prior art keywords
- weight
- copolymer
- polymer
- aromatic vinyl
- 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.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
- B60C1/0016—Compositions of the tread
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
- C08L9/06—Copolymers with styrene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S152/00—Resilient tires and wheels
- Y10S152/905—Tread composition
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S525/00—Synthetic resins or natural rubbers -- part of the class 520 series
- Y10S525/941—Polymer mixture containing block copolymer is mixed or reacted with chemical treating agent
Abstract
A B S T R A C T
ELASTOMERIC COMPOSITIONS, PROCESS FOR
THE PREPARATION THEREOF AND TYRES CONTAINING THEM
An elastomeric composition suitable for use in the tread portion of a tyre comprises (1) 10-90 %wt of copolymer A of a mono-aromatic vinyl compound and a conjugated diene, containing 10-40 %wt of mono-aromatic vinyl compound and having a vinyl content of at least 50 %wt and a Tg > 35 °C, and (2) 90-10 %wt of polymer B which is a homopolymer of a conjugated diene or a copolymer of a mono-aromatic vinyl compound and a conjugated diene, polymer B
containing < 25 %wt of mono-aromatic vinyl compound and having a vinyl content < 25% and a Tg < -55 °C, polymers A and B having a differential content of aromatic vinyl compound which varies less than 5 percentage points, as determined by monomer conversion;
and process for the preparation of the composition by mixing A and B.
ELASTOMERIC COMPOSITIONS, PROCESS FOR
THE PREPARATION THEREOF AND TYRES CONTAINING THEM
An elastomeric composition suitable for use in the tread portion of a tyre comprises (1) 10-90 %wt of copolymer A of a mono-aromatic vinyl compound and a conjugated diene, containing 10-40 %wt of mono-aromatic vinyl compound and having a vinyl content of at least 50 %wt and a Tg > 35 °C, and (2) 90-10 %wt of polymer B which is a homopolymer of a conjugated diene or a copolymer of a mono-aromatic vinyl compound and a conjugated diene, polymer B
containing < 25 %wt of mono-aromatic vinyl compound and having a vinyl content < 25% and a Tg < -55 °C, polymers A and B having a differential content of aromatic vinyl compound which varies less than 5 percentage points, as determined by monomer conversion;
and process for the preparation of the composition by mixing A and B.
Description
`` 1326~22 EL~STOMERIC COMPOSITIONS, PROOESS FOR
THE PREPARATION THEREOF AND TYRES CONTAINING THEM
The invention relates to elastomeric compositions suitable for use in the tread portion of a pneumatic tyre, to a process ~or the preparation of said elastomeric compositions, to unvulcanized elastom~ric compositions containing said elastomeric compositions and to tyres containing the elastomeric compositions in a vulcanized state.
Tyres containing elastomeric compositions in a vulcanized state should have a low roIling resistance for low ~uel consumption, a high wet grip p~rformance for good running safety of automobiles and a high resistance against abrasion. Two general classes of tread compounds can be distinguished:-a) those giving high wet grip performance combined ~: : 15 with high heat build-up characteristics, relatively high rolling resistance, a low : resistance against abrasion and having a glass : transition temperature above minus 55 C, and : ~ ~ b) those giving relatively low wet grip performance combined with low heat build-up characteristics, relatively low rolling resistance, a hig~
;~: resistance against abrasion and having a glass : transition temperature below minus 65 C.
From the above it follows that it is difficult to combine a low rolling resistance with a high wet grip performance, British patent specification 2,068,979 concerns rubber compositions comprising (A? from l0 to 90% by weight of a random st~rene-butadiene copolymer having a bound styrene content of ~rom 3 to 30~ by weight and a butadiene portion which has a 1,2 content of from 60 to 95% by weight, said copolymer being obtained by poly-merization in the presence of an organo-alkali metal catalyst, and (B) from 90 to 10% by weight of at least S one rubber having a glass transition temperature not higher than minus 40 C, said rubber being natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber or polybutadiene rubber.
"Random" according to British patent specification 2,068,979, r~fers to a styrene-butadiene copolymer, the bound styrene of which contains 10% by weight or less of block styrenP. The random styrene-butadiene copolymer (A) can be prepared, for example, by poly-merizing styrene and butadiene in a hydrocarbon solvent in the presence of an additive such as an ether or a tertiary amine and using an organolithium compound as initiator. Pneumatic tyre treads made from such com-positions have improYed wet skid and heat build-up properties.
U.S. patent specification 4,485,205 concerns elastomeric compositions suitable for use in the tread portion of a pneumatic tyre. These known compositions comprise (1) a butadiene styrene copolymer rubber containing 3-30% by weight of bound styrene and having a vinyl content in the conjugated diene units of not less than 60% by weight and a glass transition tempera-ture of -35 C to 0 C, and ~2) a diene rubber having a glass transition temperature of lower than -60 ~. The two components are n~t compatible, i.e~ the glass transition temperatures of these rubbers appear separately, i.e. they are not united.
According to ~xample 1 in s~id specification the copolymer~ we~e prepared by polymerization using n-butyl~ithium as a catalyst and potassium dodecylbenzenesulphonate and diethylene glycol dimethyl ~ 1326722 ether as a modifier in a toluene solvent at constant temperature. Pneumatic tyre treads made ~rom such compositions have a low rolling resistance, a high wet grip performance and a high resistance against abrasion.
A disadvantage of the tyres manufactured from the known elastomeric compositions described hereinbefore is that their winter per~ormance is relatively poor, which follows from their relatively high Shore hardness at a temperature of minus lO ~C. The known tyres, therefore, have a relatively poor grip on snow and ice.
It has now surprisingly been found that when the copolymerized monomers are statistically distributed over the chain o~ tha copolymer, the vulcanized compo~itions have an enhanced winter performance, whilst the low rolling resistance, high wet grip performance and high resistance against abrasion are maintained.
Accordingly, the invention provides an elastomeric composition suitable for use in the tread portion of a pneumatic tyre, said compnsition comprising:-(l) in the range of from lO to 90% by weight of a copolymer A of a mono-aromatic vinyl compound and a conjugated diene and having a content of mono-aromatic vinyl compound in the range of from lO to ~0% by weight, a vinyl content in the conjugated diene units of at least 50% by weight, calculated on total conjugated diene units, and a glass tran~ition temperature above minus 35 C, and (2) in the ranye of ~rom 90 to 10% by weight of a polymer B which i~ a homopolymer of a coniugated diene or a copolymar o~ a mono-aromatic vinyl compound and a conjugated diene, said polymer B
containing less than 25% by weight Df mono-aroma~ic vinyl compound ~nd having a vinyl content in the conjugated diene units of less than 25% and a glass transition temperature below minus said percentages by weight o~ copolymer A and polymer B
being calculated on the total of A and B, and copolymer A and polymer B, if present as a copolymer, having a differential content of the mono-aromatic vinyl compound over the polymer chain which varies le~s than five percentage points, as determined by monomer conversion.
Copolymer A and polymer B, if pre~ent as a copolymer, in the compositions according to the present invention, are statistical, that is to say, the composition does not substantially vary, i.e. the lS differential content of the aromatic vinyl compound over the polymer chain varies less than five percentage points, as determined by monomer conversion. Pre~er-ably, the dif~erential content o~ the mono-aromatic vinyl content over the polymer chain varies less than two percentage points.
It is a feature o~ the present elastomeric compositions that copolymer A and polymer B are partially oompatible with each other, that is to say, that the tan ~-temperature curve of the elastomexic composition in the vulcanized state usually shows a flat and broad maximum. The value for tan ~ gives ths tangent o~ the loss angle, also re~erred to as "loss factor"; for an explanation reference is made to : "Handbook o~ Plastic~ Test Methods", edited by R.P.
Brown, 1981, Chapter Nine.
Preferred elastomeric compositions contain in the : range o~ from 20 to 50% by weight o~ copolymer A and 80 to 50% by weight oP polymer B, calculated on the total of A and B.
- ~ 13267~2 The mono-aromatic vinyl compound is suitabIy styrene, but may be, for example, 3,5-diethylstyrene, 4-n-propylstyrene, 2,4,6-trimethylstyrene, 4-phenyl~
styrene or 4-methylstyrene. Where, ~or example, branching or cross-linking is desired a polyfunctional mono-aromatic vinyl compound can be used, for example a divinylbenzene.
The conjugated diene is one capable of co-poly-merization with styrene or with another mono-aromatic vinyl compound and such that, when polymerized with styrene or another selected mono-aromatic vinyl compound or compounds, it provides a polymer having desired elastomeric properties. The diene is pre~erably 1,3-butadiene, but may be another diene, for example 1,3-pentadiene, 2-methyl-1,3-butadi2ne (isoprene), 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene or 2,3-dimethyl-1,3-pentadiene.
Very good results have been obtained with copolymer A being derived ~rom styrene and 1,3-butadiene and polymer B from 1,3-butadiene or from styrene and 1,3-butadiene.
The term "vinyl content" as used herein refers to that portion hy weight of the con~ugated diene component of th~ copolymer which has polymerized at the : 25 1,2-positions. When the diene is 1,3-butadiene the 1,2-polymerization results in the formation of pendant vinyl yroups; where the diene is other than 1,3-buta-diene corresponding pendant groups are produced by 1,2 or 3,4-polymerization. Copoly~er A preferably has a -30 vinyl content in the conjugatad dian2 unit~ in the range of ~rom 60 to 90~ by weight, calculated on total conjugated diene units. Polymer B preferably has a vinyl content below 15% by weight.
According to a preferxed embodiment of the present invention aopolymer A and polymer B are present as 13~6722 separate polymers, i.e. not chemically bound to each other. Alternatively, they are chemically bound to each other, forming one pol~mer molecule comprising one or more blocks of copolymer A and one or more blocks of polymer B. In the latter case, the polymer molecule may be represented, for example, by the general formulae A-B-(-A)~
A-(-B-A~2 5, or A-B-(-B-A~2-s-It will be under~tood that these general formulae have been written to include either sequentially formed species or species that ha~e been formed, at least in part, by the use of coupling agents. In the latter instance, any residue of the coupling agents ha~ been ignored as an insignificant part of the general formula for high molecular weight pol~mers. When the subscript is zero in the formula A-B-(-A)~ 1 the polymer A-B is meant; and when the subscript is l, the A-B-A structure of linear form is intended. Branched structures are designated by the other ~ormulae in which the subscript is between 2 and 5; ~or example, where a tetra-functional coupling agent is used, the structure of a polymer of the formula A-B-(-B-A)2_5 would be represented by:
A
B
A-B ~ B-A
B
A
The glass transition temperature ~Tg) i5 the value found ~y mean~ of differential ~canning calorimetry.
Preferably, the glass transition temperature of copoly~er A is in the range o f f rom minus 2 5 C to plus 25 C ~nd that of polymer B below minus 65 C.
The ela~omeric compo~itions according to the present invention may be compounded with the usual compounding ingredien~, such as vulcanization compounding ingredients i.e.
vulcanizing agent~, vulcanization accelerating a~ents and vulcanization activating agen~s, antioxidants, fillers and extender oil~ which may be naphthenic, paraffinlc or, which is preferred, aromatic. It will be appreciated that unvulcanlzed elastomeric compositions comprising a blend o~ the ela~omeric compo ltion according to the present inventlon with the vulcanlzation compoundlng ingredients de~cribed above, also form an aæpect of the present invention. The preferred vulcanizing agent i~ sulphur and the preferred flller is carbon black; the curve representing tan ~ of the vulcanized compositions ag a function of the temperature is deter~ined uslng an aromatic extender oil, carbon black as a flller and sulphur a~ a vulcanizing agent. Tha carbon black i~ pre~erably present in an a~ount in the range of from 20 to 120 parts by weight, calculated on 100 parts by ~eiqht of the sum of copolymar A and polymer B.
Sulphur i~ preferably present in an amount in the ran~e o from Z0 0.5 to 5 part~ by welgh~, calculated on lOQ parts by weight of ~he 3um o~ copolymer A and polymer B. Other examples of vulcanizing agents ~re 4,4'-dithiomorphollne and alkylphenol di~ulphides. The elastomerlc compo~itlons may ~urther contain other inorganic fillers, for example sillca, bentonlte, clay, titanlum oxide, talc, diatomaceous earth7 chalk and china clay. Example~ of vulcanizatlon activating agents which may be present are zlnc oxide and stearic acid. Examples of antioxidants which may be present are N,N'-bis(1,4-dimethylphenyl)-p-phenylenediamine, ,'~",~
~326722 7a 63293-3005 N-phenyl N'-i~opropyl-p-phenylenediamine, phenyl-~-naphthylamine and 2-mercaptobenzimidazole. Examples of vulcanization acceleratlng agents are 2-~4-morphollnyl-mercapto)benzothiazole and N-cyclohexyl-2-benzothiazyl sulphenamide.
The invention further provldes a process for the preparatlon of an elastomeric composition ~ultable for ~13267~2 the use in the tread portion of a pneumatic tyre which process comprises mixing (l) in the rang~ of from 10 to 90% by weight o~ a copolymer A of a mono-aromatic vinyl compound and a conjugated diene and having a content of aromatic vinyl compound in the range of from 10 to 40% by weight, a vinyl content in the con~ugated diene units of at least 50% by weight, calculated on total conjugated diene units, and a glass transition temperature above minus 35 C, and (2) in the range of from 90 to 10% ~y weight of a polymer B which is a homopolymer of a conjugated diene or a copolymer of a mono-aromatic vinyl compound and a conjugated diene, said polymer B
containing less than 25% by weight of a mono-: aromatic vinyl compound and having a vinyl content in the conjugated diene units o~ less than 25% and a glass transition temperature below minus 55 C, said percentages by weight oE copolymer A and polymer B
being calculated on the total o~ A and B, and copolymer A and polymer B, if present as a copolymer, having a differential content of the aromatic vinyl compound over the polymer chain which varies less than five percentage points, as determined by monomer conversion.
The statistical distribution of the ~opolymeriæed : monomers over the chain of the copolymers can be : achieved in any desired manner, but preferably ~: accor~ing ~o the process described in Briti h patent ~ ; spaclfication No. 1,283,327. Therefore, according to a : ~ 30: pr~ferred embodiment of the present in~ention, copoly~er A and polymer B, i~ a copolymer, have been prepared by batch copolymerization o a conju~ated : diene and ~ mono aromatic vinyl ~ompound in the presence o~ a liquid diluent and with the aid of an initiator based on lithium, in which embodiment ~ 32~72~ `
(a) first a starting mixture is prepared from the diluent and part of the totally needed quantity of each of the monomers, (b) subsequently the copolymerization is initiated by S contacting this mixture with the initiator, and (c) during copolymerization the monomer ratio in the reaction mixture is kept con~tant (as hereinafter de~ined) by addition of the remaining part of each o~ the monomers.
The term "constant" mentioned under (c~
hereinbefore includes "substantially constant", by which should be understood that the monomer weight ratio during the copolymerization should increase or decrease by that percentage so as to yield a differential content of the aromatic vinyl compound over the polymer chain which varies less than five percentage points, as determined by monomer conversion.
In step (b) as a rule the totally needed quantity of initiator is added to the mixture mentioned under (a) under homogenization in a comparatively short time.
Usually the moment at which step (c) is started approximately coincides with that at which the addition of initiator is stopped, but it may be a little earlier or later.
The copolymerization reaction is preferably discontinued as soon as ~he addition mentioned under ~ ~c) has been completed. As a rule th~ reaction is : di~con~inued by means o~ substances which "killi' the : ~ ; livin~ polymer; thi6 can be a proton-r~leasin~
compound, ~or instance water, an alcohol, ~n amine or a protonic acid, or, which i8 preferred, a coupling agent. The coupling can be effected conveniently by use of a difunctional coupling agen~, ~or example l,2-dibromoeth~ne or a diisocyanate, providing a linear coupled copolymar, or a tri-; tetra- or other -~` 132~722 polyfunctional coupling agent, fsr example the tetra-functional compounds silicon tetrachloride, stannic chlorid~, dimethyl adipate and diethyl adipate provide a non-linear or branched coupled copolymer.
Whare the coupling is only partly complete, for example at 50% of the theoretical amount, the product o~ the coupling reaction consists partly of coupled block copolymer and partly of uncoupled block copolymer.
Consequently, two di~ferent preselected monomer ratios are applied: the monomer ratio in the mixture prepared beforehand in which the copolymerization is initiated and that in which the monomers are supplied aft~r the initiation of the copolymerization. The monomer suppletion can take place by addition either of the monomers as a mixture prepared beforehand, or o~
each monomer separately. In the present process the addition can also be carried out continuously or portion-wise. As a result of the measures mentioned, during the polymerization not only the monomer ratio in the reactor is kept constant or substantially constant, but also a decrease in concentration of the mono-aromatic vinyl compound is counteracted, which facilitates the control of the processO
It is recommended that less than 90~ by weight of the totally needed quantity of the aromatic vinyl compound be used in the preparation of the starting mixture, the application of quantities smaller than 50%
by weight of the totally needed guantity o~ the aromatic vinyl compound being particularly preferred.
Also, sper-ial preference is given to the addition of the remaining part of each o~ the monomers duriny the copolymerization at a rate equal to the rate at which the concerning mo~omer is consumed. Here l'egual"
includes l'substan~ially egual", by which should be understood that the rate is such so as to yield a 1~2~722 differential content of the aromatic vinyl compound over the polymer chain which varies less than five percentage points, as determined by monomer conversion.
Fulfilment of this condition results in that in the reactor not only the monomer ratio, but also the absolute quantity of each o~ the monomers remainæ
constant or substankially constant. In this case the decrease o~ the monomer concentration does not exceed a value determined by the increase of the polymer concentration. Under these conditions the rate at which the copolymers are applied during the copolymerizakion can be kept constant or substantially constant at a value calculated beforehand and the heat development also remains constant or substantially constant I5 throughout the polymerization.
In certain cases, when the circumstances are such that vapour lock can occur in the head of the monomer pump when using a low-boiling monomer, for instance butadiene, it is possible, in order to avoid this phenomenon, to supply the concerning monomer, or the monomer mixture in which it is contained, dissolved in a not too large amount of the liquid diluent. It is true that this causes an extra decrease in monomer concentration duriny the copolymeri2ation, but this extra decrease cvncentration decrea~e can be kept very small. Preferably, however, during the monomer suppl~tion no liquid diluent i added at the same time.
In additionl in the process it is also possible to keep the concentration of each of the monomers constant. This can be attained, for instance, when during the poly~erization each of the monomers is added, according to a certain sch2me, at a rate higher than that at which it is consumed.
- - -1~2`6722 If required, in the process the monomer concentration in the reactor can be controlled by means of gas-liquid chromatography.
As the process can also be applied ~t a relatively high monomer concentration, there is no need to carry out the copolymerization at a high temperature.
Therefore temperatures below 150 C are preferred and as a rule particular preference will be given to co-polymerization at a temperature of below llO C, most preference being given to temperatures between 30 and 100 C. ~n addition it is re~ommended that the temperature be kept constant or ~ubstantially constant.
However, it is also possible to gradually increase or decrease the temperature d-lring the polymerization.
The preferred diene/axomatic vinyl compoun~ weight ratio in the mixture in which the copolymerization reaction is initiated amounts to from 50:50 to 5:95.
Though in principle in the mixture in which the copolymerization is initiated any monomer concentration can be applied, preferably a total amount of monomer of at least 0.05% by weight is used, total amounts of from 0.1 to 10.0% by weight being particularly recommended.
In addition it is desirable that throughout the process the reaction mixture is intensively homogenized. As a rule the homogenization is brought about by means of an intensively working 6tirrer. As an initiator based on lithi~m can ~or instance be applied:
metallic lit~iu~, alkyllithium compounds, uch as methyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, amyllithium, 2-ethylhexyllithium, phenyllithium, ethylenedilithium, trimethylenedi lithium, pentamethylenedilithium, l,4-dilithiobenzene, 1,5-dilithiobenzene, 1,5-dilithlonaphthalene and 1,3,5-trilithiumpentane.
- ,r~ .
132672~
The amount of initiator may vary within wide limits. In general 0.001-l.0 g of metallic or bound lithium per 100 g o~ monomer is applied.
If required, the copolymerization can be carried out in the presencP of a slight amount of divinyl-benzene or other substance that causes branching or cross-linking of the copolymer, prior tol together with, or subsequent to the use of a coupling agent, such as silicon tetrachloride, stannic chloride, a dihalogen hydrocarbon, a monoester such as ethyl acetate, ethyl acrylate, or phenyl benzoate, or a diester, obtained by the reactien of a dicarboxylic acid with a monovalent alcohol, such as diethyl adipate. In addition the process can be applied in combination with the use of polar organic compounds, for example as described in the British patent specification No. 884,490, which modify the initiator in such a way that statistic copolymerization is promoted. In this way, the microstructure of the diene part of the copolymer i~ also changed to the effect that the percentage of 1,2-addition structure increases.
Suitable examples of diluent~- are aliphatic and aromatic hydrocarbons, such as pentane, hexane, heptane, petroleum ether, benzene, cyclopentane, cyclo-hexane, xylene, isooctane, 2-butene, 2-~ethyl-1-butene or mixtures of two or more of these hydrocarbons. As a rule diluent~ are used in which the copol~mers formed dis~olvs.
The i~v~ntion is further illustrated by means of the following Examples.
The trade names used ln the Examples and Compara-tiYe Experiments have tbe following signification:
"Dutrex'~ is an aromatic sxtender oil having a density 20/4 ~C of 0.996, carbon atom~ in aromatic structure 40%, in naphthenic structur~ 34% and in paraffinic structure of 26~, and a kinematic viscosity at 37.8 C
and 100 C of 727 mm~/s and 17.3 mm2/s~ respectively.
"Carbon black ISA~ N220" is an intermediate superabrasion furnace black according to ASTN method D 1765.
"Santoflex 13n is N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, an antidegradant.
"Santocure CBS" is N-cyclohexyl-2-benzothiazylsulphen-amide, an accelerator.
The curves representing tan ~ of the vulcanized compositions as a ~unction of the temperature were determined over a temperature range of minus 100 C to plus 100 C at a strain amplitude of 0.5~ and a frequency of lO Hz. A rectangular strip specimen having a length of 35 mm, a width o~ 12.7 mm and a thickness of 2.1 mm was used.
The wet grip per~ormance was assessed from dynamic mechanical measurements on cylindrical specimens having a height of 6 mm and a diameter of 6 mm, determining the ratio between the loss modulus and storage shear modulus at O C, 1.5 Hz and 0.5~ strain amplitude.
The rolling resistance was measured on samples : with the same geometry determining the ratio between the loss modulus and storage shear modulus at 50 C, 10 ~z and 2% strain amplitude.
The apparatus used for both measurements was a - ~ Rheometrics dynam~c mechanical spectrometer, type system 4.
The values for tan ~ were calculated as the ratio of loss modulus and storagP shear modulus. The rolling resistance Rc was calcul~ed by means o~ the following equation:
Rc = 26.25 G~ ~ 0-277 x G" ~ 66 ~G*)2 32~22 in which G" is the loss shear modulus expressed in MPa and G* is the complex shear modulus expressed in MPa.
The abrasion resistance has been determined according to DIN 53516.
Preparation of copolymer Al A stainless steel reaction vessel provided with a `~
stirrer and having a capacity of 30 1 was charged with 22 1 of cyclohexane and heated to a temperature of 45 C. Then, a starting mixture of 122 g of styrene and 85 g of 1,3-butadiene, which also contained 1-tert-butoxy-2-n-butoxyethane ~26.7 ml), was dissolved in the cyclohexane. The copolymerization was initiated by addition of ~ec-butyllithium (14.3 mmol), thus simultaneously titrating impurities and initiating the : 15 polymerization. This initiation was immediately followed by gradual addition o~ a mixture of 750 g o~
styrene and 1750 g of butadiene over a period of 300 min.
After the gradual addition of the mixture of monomers the active polymer chains were terminated by addition o~ diethyl adipate in an amount stoichiometric with respect to the amount of sec-butyllithium. ~he coupling reaction was continued for 30 min. ~he polymers were stabilized by addiny 0.6~ by weight o~
~ 2,6-di-tert-butyl-p-cr2sol~ i olated by mean~ of ~team ~ coagulation and dried at F~ub-atmospheric pre~sure.
: : : Preparation of coPolymers Bl and B3 ~, : A stainless steel reaction vessel provided with a stirrer and having a capacity of 10 1 was charged with 6.6 1 of cyclohexane and heat~d to a temperature of 70 C. ~hen, a starting mixture of 93.6 g of Qtyrene and 29.3 g o~ 1,3-butadiene was dissolved in the cyclo-hexane. ~he copolymerization was initiated by addition of sec-butyllithium ~5.9 ~mol), thus simultaneously titrating impurities and initiating the polymerization.
This initiation was immediately followed by gradual addition of a mixture of 180 g of styrene and 820 g of butadiene over a period of 180 min.
After the gradual addition o~ the mixture of monomers the active polymer chains were terminated by addition of diethyl adipate in an amount stoichiometric with respect to the amount of sec-butyllithium. ~he coupling reaction was continued for 30 min. The polymers were stabilized by adding 0~6% by weight of 2,6-di-tert-butyl-p-cresol, isolated by means of steam coagulation and dried at sub-atmospheric pressure.
Two batches were prepared in thi5 manner, referred to hereina~t~r as "Bl" and "B3".
Preparation of polYmer B2 A stainless steel reaction vessel provided with a stirrer and having a capacity of 30 1 was charged with 20 1 of cyclohexane and heated to a temperature of 70 C. Then, 1000 g of 1,3-butadiene was dissolved in the cyclohexane. The polymerization wa~ initiated by addition of sec-butyllithium (13.2 mmol), thus simultaneously titrating impurities and initiating the polymerizatIon. This ini~iation was immediately followed *y gradual addition of 1500 g of butadiene over a period of 60 min.
After the gradual addition of mon~mer the ; ~ polymerization was allowed to prvceed ~or 60 min. Then, the active polymer chains were ter~inated by addition of diethyl adipate in an amount stoichiometric with respest to the a~ount of s~c-butyllithium. The coupling reaction was continued ~or 30 min. The polymsr~ were stabilized by adding 0.6% by weight of 2,6-di-tert-butyl-p-~-resol, isolated by means o~ steam coa~ulation and dried at sub-atmospheric pressure.
132~72~
Preparation of copolymer AX
A stainless steel reaction vessel provided with a stirrer and having a capacity of 10 1 was charged with 6.6 1 of cyclohexane. Then, a mixture of 180 g of styrene and 820 g of butadiene which also contained 2.3 ml of l-tert-butoxy-2-n-butoxyethane, was dissolved in the cyclohexane. The polymerization was initiated by addition of sec-butyllithium (4.8 mmol), thus imul-taneously titrating impurities and initiating the polymerization, and carried out at a temperature of The polymerization was allowPd to proceed for 720 min. Then, the active polymer chains were terminated by addition of diethyl adipate in an amount stoichiometric with respect to the amount of sec-butyllithium. The coupling reaction was continued for 30 min. The polymers were stabilized by adding 0.6% by weight of 2,6-di-tert-butyl-p-cresol, isolated by means of steam coagulation and dried at sub-atmospheric pressure.
Preparation of copolymer AY
A stainless steel reaction vessel provided with a stirrer and having a capacity of 27.5 1 was charged with 22 1 of cyclohexane and heated to a tempQrature of 45 C. Then, a starting mixtur of 900 g of ~tyrene and 2 g of 1,3-butadiene was dissolved in the cyclohexane, ~ollowed by addition of l-tert-butoxy-2-n-butoxyethane (24 ml, 1000 parts per million by weight). The copolymerization w~s initiated by addition of sec-butyllithiu~ (18.3 mmol), thus simultaneously titratin~ impurities and initiating the polymerization.
This initiation was immediately followed by gradual addition o~ 209B g o~ butadiene over a period of 150 min, followed by allowing the mixture to polymerize for a further 30 min. Then, the active polymer chains were terminated by addition of diethyl adipate in an 1326~22 amount stoichiometric with respact to the amount of sec-butyllithium. The coupling reaction was continued for 30 min. The polymers were stabilized by a~ding 0.6%
by weight of 2,6 di-tert-butyl-p-cresol, isolated by means of steam coagulation and dried at sub-atmospheric pressure.
Preparation of copolymer BX
A stainless steel reaction vessel provided with a stirrer and having a capacity of 20 l was charged with 15 1 of cyclohexane and heated to a temperature o~
70 C. Then, a starting mixture of 3GO g of styrene and 575 g o~ butadiene was dissolved in the cyclohexane.
The copolymerization was initiated by addition of sec butyllithium (5.6 mmol), thus simultaneously titrating impurities and initiating the polymerization.
Ten minutes after the initiation followed a gradual addition of 125 g o~ butadiene over a period of 13 min, followed by allowing the mixture to polymerize for a further 28 min. Then, the active polymer chains were 2U terminated by addition o~ diethyl adipate in an amount stoichiometric with respect to the amount o~ sea~butyl-lithium. The coupling reaction was continued ~or 30 min. The polymers wer~ stabilized by adding 0.6~ by weight of 2,6-di-tert-butyl-p-cresol, isolated by means of steam coagulation and dried at sub-atmospheric pressure.
A few properties of polymer~ Al, Bl, B2, ~3, ~X, AY and BX are stat~d in Table l hereinafter. Table l ~hows that polymers Al, ~X and AY comply with the requirements o~ ~tyrene content, vinyl content and Tg o~ copoly~er A and that polym~rs B1, B2, B3 ~nd BY
comply with these thræe requirement~ for polymer B
which are pr~sent in the compositions according to the invention.
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3~6722 Figures l and 2 of the accompanying drawing show a plot of perc~ntage differ~ntial styrene content in the polymer against total monomer conversion expressed in a percentage, the upper, dotted, line in Figure l relating to copolymer Al and the lower line to copolymers Bl and B3, and the lines in Figure 2 relating to copolymers AX, AY and BX.
It can be seen that copolymers Al, Bl ~nd B3 are true random copolymers having a constant average styrene content throughout the polymer molecule, i.e. the styrene content of successive incremental portions of the molecule is substantially co~stant throughout~ In contradistinction hereto, the styrene content of successive incrsmental portions of the molecule of copolymer AX become progressively larger, as shown in Eigure 2, copolymer AX not complying with the requirement of the differential content of styrene over the polymer chain which is less than ~ive percentage points, as determined by monomer conversion. It can also be seen that copolymers AY and BX do not comply with the latter requirement.
Examples l and 2 and Comparative Experiments A-E
Seven elastomeric compositions were produced from the polymers Al, Bl, B2, B3, AX, AY and BX and rom Dutrex 729 extender oil, using the weight ratio~ stated in Table 2. This table also states the Mooney viscosity of the mixtures. The elastomeric compositions contained 37.5 parts by weight of the extender oil on lO0 paxts by ; weight o~ polymer. Elastomeric compositions 1 and 2 are according ~o the pr~s~nt invention, elastomeric compositions 3-7 are not.
~326722 Table 2 Elastomeric Components andMooney composition weight ratioviscosity MLj(1+4~, 100 C
1 Bl/Al 60:40 33 2 B2/A1 70:30 47 3 B3/AX 60:40 41 4 BX/AX 60:40 46 BX/AY 60:40 43 6 B3/AY 60:40 36 7 BX/A1 60:40 43 Seven vulcanized elastomeric compositions were produced by using the elastomeric compositions 1-7 according to the compounding recipe shown in Tabla 3 and using optimum cure time at 160 C according to method ASTM D 2084.
~able 3 Ingredient Parts by weight Elastomeric composition 137.5 Zinç oxide 3.0 Stearic acid 2.0 Santoflex 13~ * 1.0 Carbon black ISAF N220 95.0 Dutrex 729~ 12~5 Sulphur 2.0 Santocure (CBS) 1.5 Analytical data on the seven vulcanized elastomexic composition are presented in Table 4. Examples 1 and 2 are according to the present invention, Comparative Experiments A-E are not.
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_I rl o I
THE PREPARATION THEREOF AND TYRES CONTAINING THEM
The invention relates to elastomeric compositions suitable for use in the tread portion of a pneumatic tyre, to a process ~or the preparation of said elastomeric compositions, to unvulcanized elastom~ric compositions containing said elastomeric compositions and to tyres containing the elastomeric compositions in a vulcanized state.
Tyres containing elastomeric compositions in a vulcanized state should have a low roIling resistance for low ~uel consumption, a high wet grip p~rformance for good running safety of automobiles and a high resistance against abrasion. Two general classes of tread compounds can be distinguished:-a) those giving high wet grip performance combined ~: : 15 with high heat build-up characteristics, relatively high rolling resistance, a low : resistance against abrasion and having a glass : transition temperature above minus 55 C, and : ~ ~ b) those giving relatively low wet grip performance combined with low heat build-up characteristics, relatively low rolling resistance, a hig~
;~: resistance against abrasion and having a glass : transition temperature below minus 65 C.
From the above it follows that it is difficult to combine a low rolling resistance with a high wet grip performance, British patent specification 2,068,979 concerns rubber compositions comprising (A? from l0 to 90% by weight of a random st~rene-butadiene copolymer having a bound styrene content of ~rom 3 to 30~ by weight and a butadiene portion which has a 1,2 content of from 60 to 95% by weight, said copolymer being obtained by poly-merization in the presence of an organo-alkali metal catalyst, and (B) from 90 to 10% by weight of at least S one rubber having a glass transition temperature not higher than minus 40 C, said rubber being natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber or polybutadiene rubber.
"Random" according to British patent specification 2,068,979, r~fers to a styrene-butadiene copolymer, the bound styrene of which contains 10% by weight or less of block styrenP. The random styrene-butadiene copolymer (A) can be prepared, for example, by poly-merizing styrene and butadiene in a hydrocarbon solvent in the presence of an additive such as an ether or a tertiary amine and using an organolithium compound as initiator. Pneumatic tyre treads made from such com-positions have improYed wet skid and heat build-up properties.
U.S. patent specification 4,485,205 concerns elastomeric compositions suitable for use in the tread portion of a pneumatic tyre. These known compositions comprise (1) a butadiene styrene copolymer rubber containing 3-30% by weight of bound styrene and having a vinyl content in the conjugated diene units of not less than 60% by weight and a glass transition tempera-ture of -35 C to 0 C, and ~2) a diene rubber having a glass transition temperature of lower than -60 ~. The two components are n~t compatible, i.e~ the glass transition temperatures of these rubbers appear separately, i.e. they are not united.
According to ~xample 1 in s~id specification the copolymer~ we~e prepared by polymerization using n-butyl~ithium as a catalyst and potassium dodecylbenzenesulphonate and diethylene glycol dimethyl ~ 1326722 ether as a modifier in a toluene solvent at constant temperature. Pneumatic tyre treads made ~rom such compositions have a low rolling resistance, a high wet grip performance and a high resistance against abrasion.
A disadvantage of the tyres manufactured from the known elastomeric compositions described hereinbefore is that their winter per~ormance is relatively poor, which follows from their relatively high Shore hardness at a temperature of minus lO ~C. The known tyres, therefore, have a relatively poor grip on snow and ice.
It has now surprisingly been found that when the copolymerized monomers are statistically distributed over the chain o~ tha copolymer, the vulcanized compo~itions have an enhanced winter performance, whilst the low rolling resistance, high wet grip performance and high resistance against abrasion are maintained.
Accordingly, the invention provides an elastomeric composition suitable for use in the tread portion of a pneumatic tyre, said compnsition comprising:-(l) in the range of from lO to 90% by weight of a copolymer A of a mono-aromatic vinyl compound and a conjugated diene and having a content of mono-aromatic vinyl compound in the range of from lO to ~0% by weight, a vinyl content in the conjugated diene units of at least 50% by weight, calculated on total conjugated diene units, and a glass tran~ition temperature above minus 35 C, and (2) in the ranye of ~rom 90 to 10% by weight of a polymer B which i~ a homopolymer of a coniugated diene or a copolymar o~ a mono-aromatic vinyl compound and a conjugated diene, said polymer B
containing less than 25% by weight Df mono-aroma~ic vinyl compound ~nd having a vinyl content in the conjugated diene units of less than 25% and a glass transition temperature below minus said percentages by weight o~ copolymer A and polymer B
being calculated on the total of A and B, and copolymer A and polymer B, if present as a copolymer, having a differential content of the mono-aromatic vinyl compound over the polymer chain which varies le~s than five percentage points, as determined by monomer conversion.
Copolymer A and polymer B, if pre~ent as a copolymer, in the compositions according to the present invention, are statistical, that is to say, the composition does not substantially vary, i.e. the lS differential content of the aromatic vinyl compound over the polymer chain varies less than five percentage points, as determined by monomer conversion. Pre~er-ably, the dif~erential content o~ the mono-aromatic vinyl content over the polymer chain varies less than two percentage points.
It is a feature o~ the present elastomeric compositions that copolymer A and polymer B are partially oompatible with each other, that is to say, that the tan ~-temperature curve of the elastomexic composition in the vulcanized state usually shows a flat and broad maximum. The value for tan ~ gives ths tangent o~ the loss angle, also re~erred to as "loss factor"; for an explanation reference is made to : "Handbook o~ Plastic~ Test Methods", edited by R.P.
Brown, 1981, Chapter Nine.
Preferred elastomeric compositions contain in the : range o~ from 20 to 50% by weight o~ copolymer A and 80 to 50% by weight oP polymer B, calculated on the total of A and B.
- ~ 13267~2 The mono-aromatic vinyl compound is suitabIy styrene, but may be, for example, 3,5-diethylstyrene, 4-n-propylstyrene, 2,4,6-trimethylstyrene, 4-phenyl~
styrene or 4-methylstyrene. Where, ~or example, branching or cross-linking is desired a polyfunctional mono-aromatic vinyl compound can be used, for example a divinylbenzene.
The conjugated diene is one capable of co-poly-merization with styrene or with another mono-aromatic vinyl compound and such that, when polymerized with styrene or another selected mono-aromatic vinyl compound or compounds, it provides a polymer having desired elastomeric properties. The diene is pre~erably 1,3-butadiene, but may be another diene, for example 1,3-pentadiene, 2-methyl-1,3-butadi2ne (isoprene), 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene or 2,3-dimethyl-1,3-pentadiene.
Very good results have been obtained with copolymer A being derived ~rom styrene and 1,3-butadiene and polymer B from 1,3-butadiene or from styrene and 1,3-butadiene.
The term "vinyl content" as used herein refers to that portion hy weight of the con~ugated diene component of th~ copolymer which has polymerized at the : 25 1,2-positions. When the diene is 1,3-butadiene the 1,2-polymerization results in the formation of pendant vinyl yroups; where the diene is other than 1,3-buta-diene corresponding pendant groups are produced by 1,2 or 3,4-polymerization. Copoly~er A preferably has a -30 vinyl content in the conjugatad dian2 unit~ in the range of ~rom 60 to 90~ by weight, calculated on total conjugated diene units. Polymer B preferably has a vinyl content below 15% by weight.
According to a preferxed embodiment of the present invention aopolymer A and polymer B are present as 13~6722 separate polymers, i.e. not chemically bound to each other. Alternatively, they are chemically bound to each other, forming one pol~mer molecule comprising one or more blocks of copolymer A and one or more blocks of polymer B. In the latter case, the polymer molecule may be represented, for example, by the general formulae A-B-(-A)~
A-(-B-A~2 5, or A-B-(-B-A~2-s-It will be under~tood that these general formulae have been written to include either sequentially formed species or species that ha~e been formed, at least in part, by the use of coupling agents. In the latter instance, any residue of the coupling agents ha~ been ignored as an insignificant part of the general formula for high molecular weight pol~mers. When the subscript is zero in the formula A-B-(-A)~ 1 the polymer A-B is meant; and when the subscript is l, the A-B-A structure of linear form is intended. Branched structures are designated by the other ~ormulae in which the subscript is between 2 and 5; ~or example, where a tetra-functional coupling agent is used, the structure of a polymer of the formula A-B-(-B-A)2_5 would be represented by:
A
B
A-B ~ B-A
B
A
The glass transition temperature ~Tg) i5 the value found ~y mean~ of differential ~canning calorimetry.
Preferably, the glass transition temperature of copoly~er A is in the range o f f rom minus 2 5 C to plus 25 C ~nd that of polymer B below minus 65 C.
The ela~omeric compo~itions according to the present invention may be compounded with the usual compounding ingredien~, such as vulcanization compounding ingredients i.e.
vulcanizing agent~, vulcanization accelerating a~ents and vulcanization activating agen~s, antioxidants, fillers and extender oil~ which may be naphthenic, paraffinlc or, which is preferred, aromatic. It will be appreciated that unvulcanlzed elastomeric compositions comprising a blend o~ the ela~omeric compo ltion according to the present inventlon with the vulcanlzation compoundlng ingredients de~cribed above, also form an aæpect of the present invention. The preferred vulcanizing agent i~ sulphur and the preferred flller is carbon black; the curve representing tan ~ of the vulcanized compositions ag a function of the temperature is deter~ined uslng an aromatic extender oil, carbon black as a flller and sulphur a~ a vulcanizing agent. Tha carbon black i~ pre~erably present in an a~ount in the range of from 20 to 120 parts by weight, calculated on 100 parts by ~eiqht of the sum of copolymar A and polymer B.
Sulphur i~ preferably present in an amount in the ran~e o from Z0 0.5 to 5 part~ by welgh~, calculated on lOQ parts by weight of ~he 3um o~ copolymer A and polymer B. Other examples of vulcanizing agents ~re 4,4'-dithiomorphollne and alkylphenol di~ulphides. The elastomerlc compo~itlons may ~urther contain other inorganic fillers, for example sillca, bentonlte, clay, titanlum oxide, talc, diatomaceous earth7 chalk and china clay. Example~ of vulcanizatlon activating agents which may be present are zlnc oxide and stearic acid. Examples of antioxidants which may be present are N,N'-bis(1,4-dimethylphenyl)-p-phenylenediamine, ,'~",~
~326722 7a 63293-3005 N-phenyl N'-i~opropyl-p-phenylenediamine, phenyl-~-naphthylamine and 2-mercaptobenzimidazole. Examples of vulcanization acceleratlng agents are 2-~4-morphollnyl-mercapto)benzothiazole and N-cyclohexyl-2-benzothiazyl sulphenamide.
The invention further provldes a process for the preparatlon of an elastomeric composition ~ultable for ~13267~2 the use in the tread portion of a pneumatic tyre which process comprises mixing (l) in the rang~ of from 10 to 90% by weight o~ a copolymer A of a mono-aromatic vinyl compound and a conjugated diene and having a content of aromatic vinyl compound in the range of from 10 to 40% by weight, a vinyl content in the con~ugated diene units of at least 50% by weight, calculated on total conjugated diene units, and a glass transition temperature above minus 35 C, and (2) in the range of from 90 to 10% ~y weight of a polymer B which is a homopolymer of a conjugated diene or a copolymer of a mono-aromatic vinyl compound and a conjugated diene, said polymer B
containing less than 25% by weight of a mono-: aromatic vinyl compound and having a vinyl content in the conjugated diene units o~ less than 25% and a glass transition temperature below minus 55 C, said percentages by weight oE copolymer A and polymer B
being calculated on the total o~ A and B, and copolymer A and polymer B, if present as a copolymer, having a differential content of the aromatic vinyl compound over the polymer chain which varies less than five percentage points, as determined by monomer conversion.
The statistical distribution of the ~opolymeriæed : monomers over the chain of the copolymers can be : achieved in any desired manner, but preferably ~: accor~ing ~o the process described in Briti h patent ~ ; spaclfication No. 1,283,327. Therefore, according to a : ~ 30: pr~ferred embodiment of the present in~ention, copoly~er A and polymer B, i~ a copolymer, have been prepared by batch copolymerization o a conju~ated : diene and ~ mono aromatic vinyl ~ompound in the presence o~ a liquid diluent and with the aid of an initiator based on lithium, in which embodiment ~ 32~72~ `
(a) first a starting mixture is prepared from the diluent and part of the totally needed quantity of each of the monomers, (b) subsequently the copolymerization is initiated by S contacting this mixture with the initiator, and (c) during copolymerization the monomer ratio in the reaction mixture is kept con~tant (as hereinafter de~ined) by addition of the remaining part of each o~ the monomers.
The term "constant" mentioned under (c~
hereinbefore includes "substantially constant", by which should be understood that the monomer weight ratio during the copolymerization should increase or decrease by that percentage so as to yield a differential content of the aromatic vinyl compound over the polymer chain which varies less than five percentage points, as determined by monomer conversion.
In step (b) as a rule the totally needed quantity of initiator is added to the mixture mentioned under (a) under homogenization in a comparatively short time.
Usually the moment at which step (c) is started approximately coincides with that at which the addition of initiator is stopped, but it may be a little earlier or later.
The copolymerization reaction is preferably discontinued as soon as ~he addition mentioned under ~ ~c) has been completed. As a rule th~ reaction is : di~con~inued by means o~ substances which "killi' the : ~ ; livin~ polymer; thi6 can be a proton-r~leasin~
compound, ~or instance water, an alcohol, ~n amine or a protonic acid, or, which i8 preferred, a coupling agent. The coupling can be effected conveniently by use of a difunctional coupling agen~, ~or example l,2-dibromoeth~ne or a diisocyanate, providing a linear coupled copolymar, or a tri-; tetra- or other -~` 132~722 polyfunctional coupling agent, fsr example the tetra-functional compounds silicon tetrachloride, stannic chlorid~, dimethyl adipate and diethyl adipate provide a non-linear or branched coupled copolymer.
Whare the coupling is only partly complete, for example at 50% of the theoretical amount, the product o~ the coupling reaction consists partly of coupled block copolymer and partly of uncoupled block copolymer.
Consequently, two di~ferent preselected monomer ratios are applied: the monomer ratio in the mixture prepared beforehand in which the copolymerization is initiated and that in which the monomers are supplied aft~r the initiation of the copolymerization. The monomer suppletion can take place by addition either of the monomers as a mixture prepared beforehand, or o~
each monomer separately. In the present process the addition can also be carried out continuously or portion-wise. As a result of the measures mentioned, during the polymerization not only the monomer ratio in the reactor is kept constant or substantially constant, but also a decrease in concentration of the mono-aromatic vinyl compound is counteracted, which facilitates the control of the processO
It is recommended that less than 90~ by weight of the totally needed quantity of the aromatic vinyl compound be used in the preparation of the starting mixture, the application of quantities smaller than 50%
by weight of the totally needed guantity o~ the aromatic vinyl compound being particularly preferred.
Also, sper-ial preference is given to the addition of the remaining part of each o~ the monomers duriny the copolymerization at a rate equal to the rate at which the concerning mo~omer is consumed. Here l'egual"
includes l'substan~ially egual", by which should be understood that the rate is such so as to yield a 1~2~722 differential content of the aromatic vinyl compound over the polymer chain which varies less than five percentage points, as determined by monomer conversion.
Fulfilment of this condition results in that in the reactor not only the monomer ratio, but also the absolute quantity of each o~ the monomers remainæ
constant or substankially constant. In this case the decrease o~ the monomer concentration does not exceed a value determined by the increase of the polymer concentration. Under these conditions the rate at which the copolymers are applied during the copolymerizakion can be kept constant or substantially constant at a value calculated beforehand and the heat development also remains constant or substantially constant I5 throughout the polymerization.
In certain cases, when the circumstances are such that vapour lock can occur in the head of the monomer pump when using a low-boiling monomer, for instance butadiene, it is possible, in order to avoid this phenomenon, to supply the concerning monomer, or the monomer mixture in which it is contained, dissolved in a not too large amount of the liquid diluent. It is true that this causes an extra decrease in monomer concentration duriny the copolymeri2ation, but this extra decrease cvncentration decrea~e can be kept very small. Preferably, however, during the monomer suppl~tion no liquid diluent i added at the same time.
In additionl in the process it is also possible to keep the concentration of each of the monomers constant. This can be attained, for instance, when during the poly~erization each of the monomers is added, according to a certain sch2me, at a rate higher than that at which it is consumed.
- - -1~2`6722 If required, in the process the monomer concentration in the reactor can be controlled by means of gas-liquid chromatography.
As the process can also be applied ~t a relatively high monomer concentration, there is no need to carry out the copolymerization at a high temperature.
Therefore temperatures below 150 C are preferred and as a rule particular preference will be given to co-polymerization at a temperature of below llO C, most preference being given to temperatures between 30 and 100 C. ~n addition it is re~ommended that the temperature be kept constant or ~ubstantially constant.
However, it is also possible to gradually increase or decrease the temperature d-lring the polymerization.
The preferred diene/axomatic vinyl compoun~ weight ratio in the mixture in which the copolymerization reaction is initiated amounts to from 50:50 to 5:95.
Though in principle in the mixture in which the copolymerization is initiated any monomer concentration can be applied, preferably a total amount of monomer of at least 0.05% by weight is used, total amounts of from 0.1 to 10.0% by weight being particularly recommended.
In addition it is desirable that throughout the process the reaction mixture is intensively homogenized. As a rule the homogenization is brought about by means of an intensively working 6tirrer. As an initiator based on lithi~m can ~or instance be applied:
metallic lit~iu~, alkyllithium compounds, uch as methyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, amyllithium, 2-ethylhexyllithium, phenyllithium, ethylenedilithium, trimethylenedi lithium, pentamethylenedilithium, l,4-dilithiobenzene, 1,5-dilithiobenzene, 1,5-dilithlonaphthalene and 1,3,5-trilithiumpentane.
- ,r~ .
132672~
The amount of initiator may vary within wide limits. In general 0.001-l.0 g of metallic or bound lithium per 100 g o~ monomer is applied.
If required, the copolymerization can be carried out in the presencP of a slight amount of divinyl-benzene or other substance that causes branching or cross-linking of the copolymer, prior tol together with, or subsequent to the use of a coupling agent, such as silicon tetrachloride, stannic chloride, a dihalogen hydrocarbon, a monoester such as ethyl acetate, ethyl acrylate, or phenyl benzoate, or a diester, obtained by the reactien of a dicarboxylic acid with a monovalent alcohol, such as diethyl adipate. In addition the process can be applied in combination with the use of polar organic compounds, for example as described in the British patent specification No. 884,490, which modify the initiator in such a way that statistic copolymerization is promoted. In this way, the microstructure of the diene part of the copolymer i~ also changed to the effect that the percentage of 1,2-addition structure increases.
Suitable examples of diluent~- are aliphatic and aromatic hydrocarbons, such as pentane, hexane, heptane, petroleum ether, benzene, cyclopentane, cyclo-hexane, xylene, isooctane, 2-butene, 2-~ethyl-1-butene or mixtures of two or more of these hydrocarbons. As a rule diluent~ are used in which the copol~mers formed dis~olvs.
The i~v~ntion is further illustrated by means of the following Examples.
The trade names used ln the Examples and Compara-tiYe Experiments have tbe following signification:
"Dutrex'~ is an aromatic sxtender oil having a density 20/4 ~C of 0.996, carbon atom~ in aromatic structure 40%, in naphthenic structur~ 34% and in paraffinic structure of 26~, and a kinematic viscosity at 37.8 C
and 100 C of 727 mm~/s and 17.3 mm2/s~ respectively.
"Carbon black ISA~ N220" is an intermediate superabrasion furnace black according to ASTN method D 1765.
"Santoflex 13n is N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, an antidegradant.
"Santocure CBS" is N-cyclohexyl-2-benzothiazylsulphen-amide, an accelerator.
The curves representing tan ~ of the vulcanized compositions as a ~unction of the temperature were determined over a temperature range of minus 100 C to plus 100 C at a strain amplitude of 0.5~ and a frequency of lO Hz. A rectangular strip specimen having a length of 35 mm, a width o~ 12.7 mm and a thickness of 2.1 mm was used.
The wet grip per~ormance was assessed from dynamic mechanical measurements on cylindrical specimens having a height of 6 mm and a diameter of 6 mm, determining the ratio between the loss modulus and storage shear modulus at O C, 1.5 Hz and 0.5~ strain amplitude.
The rolling resistance was measured on samples : with the same geometry determining the ratio between the loss modulus and storage shear modulus at 50 C, 10 ~z and 2% strain amplitude.
The apparatus used for both measurements was a - ~ Rheometrics dynam~c mechanical spectrometer, type system 4.
The values for tan ~ were calculated as the ratio of loss modulus and storagP shear modulus. The rolling resistance Rc was calcul~ed by means o~ the following equation:
Rc = 26.25 G~ ~ 0-277 x G" ~ 66 ~G*)2 32~22 in which G" is the loss shear modulus expressed in MPa and G* is the complex shear modulus expressed in MPa.
The abrasion resistance has been determined according to DIN 53516.
Preparation of copolymer Al A stainless steel reaction vessel provided with a `~
stirrer and having a capacity of 30 1 was charged with 22 1 of cyclohexane and heated to a temperature of 45 C. Then, a starting mixture of 122 g of styrene and 85 g of 1,3-butadiene, which also contained 1-tert-butoxy-2-n-butoxyethane ~26.7 ml), was dissolved in the cyclohexane. The copolymerization was initiated by addition of ~ec-butyllithium (14.3 mmol), thus simultaneously titrating impurities and initiating the : 15 polymerization. This initiation was immediately followed by gradual addition o~ a mixture of 750 g o~
styrene and 1750 g of butadiene over a period of 300 min.
After the gradual addition of the mixture of monomers the active polymer chains were terminated by addition o~ diethyl adipate in an amount stoichiometric with respect to the amount of sec-butyllithium. ~he coupling reaction was continued for 30 min. ~he polymers were stabilized by addiny 0.6~ by weight o~
~ 2,6-di-tert-butyl-p-cr2sol~ i olated by mean~ of ~team ~ coagulation and dried at F~ub-atmospheric pre~sure.
: : : Preparation of coPolymers Bl and B3 ~, : A stainless steel reaction vessel provided with a stirrer and having a capacity of 10 1 was charged with 6.6 1 of cyclohexane and heat~d to a temperature of 70 C. ~hen, a starting mixture of 93.6 g of Qtyrene and 29.3 g o~ 1,3-butadiene was dissolved in the cyclo-hexane. ~he copolymerization was initiated by addition of sec-butyllithium ~5.9 ~mol), thus simultaneously titrating impurities and initiating the polymerization.
This initiation was immediately followed by gradual addition of a mixture of 180 g of styrene and 820 g of butadiene over a period of 180 min.
After the gradual addition o~ the mixture of monomers the active polymer chains were terminated by addition of diethyl adipate in an amount stoichiometric with respect to the amount of sec-butyllithium. ~he coupling reaction was continued for 30 min. The polymers were stabilized by adding 0~6% by weight of 2,6-di-tert-butyl-p-cresol, isolated by means of steam coagulation and dried at sub-atmospheric pressure.
Two batches were prepared in thi5 manner, referred to hereina~t~r as "Bl" and "B3".
Preparation of polYmer B2 A stainless steel reaction vessel provided with a stirrer and having a capacity of 30 1 was charged with 20 1 of cyclohexane and heated to a temperature of 70 C. Then, 1000 g of 1,3-butadiene was dissolved in the cyclohexane. The polymerization wa~ initiated by addition of sec-butyllithium (13.2 mmol), thus simultaneously titrating impurities and initiating the polymerizatIon. This ini~iation was immediately followed *y gradual addition of 1500 g of butadiene over a period of 60 min.
After the gradual addition of mon~mer the ; ~ polymerization was allowed to prvceed ~or 60 min. Then, the active polymer chains were ter~inated by addition of diethyl adipate in an amount stoichiometric with respest to the a~ount of s~c-butyllithium. The coupling reaction was continued ~or 30 min. The polymsr~ were stabilized by adding 0.6% by weight of 2,6-di-tert-butyl-p-~-resol, isolated by means o~ steam coa~ulation and dried at sub-atmospheric pressure.
132~72~
Preparation of copolymer AX
A stainless steel reaction vessel provided with a stirrer and having a capacity of 10 1 was charged with 6.6 1 of cyclohexane. Then, a mixture of 180 g of styrene and 820 g of butadiene which also contained 2.3 ml of l-tert-butoxy-2-n-butoxyethane, was dissolved in the cyclohexane. The polymerization was initiated by addition of sec-butyllithium (4.8 mmol), thus imul-taneously titrating impurities and initiating the polymerization, and carried out at a temperature of The polymerization was allowPd to proceed for 720 min. Then, the active polymer chains were terminated by addition of diethyl adipate in an amount stoichiometric with respect to the amount of sec-butyllithium. The coupling reaction was continued for 30 min. The polymers were stabilized by adding 0.6% by weight of 2,6-di-tert-butyl-p-cresol, isolated by means of steam coagulation and dried at sub-atmospheric pressure.
Preparation of copolymer AY
A stainless steel reaction vessel provided with a stirrer and having a capacity of 27.5 1 was charged with 22 1 of cyclohexane and heated to a tempQrature of 45 C. Then, a starting mixtur of 900 g of ~tyrene and 2 g of 1,3-butadiene was dissolved in the cyclohexane, ~ollowed by addition of l-tert-butoxy-2-n-butoxyethane (24 ml, 1000 parts per million by weight). The copolymerization w~s initiated by addition of sec-butyllithiu~ (18.3 mmol), thus simultaneously titratin~ impurities and initiating the polymerization.
This initiation was immediately followed by gradual addition o~ 209B g o~ butadiene over a period of 150 min, followed by allowing the mixture to polymerize for a further 30 min. Then, the active polymer chains were terminated by addition of diethyl adipate in an 1326~22 amount stoichiometric with respact to the amount of sec-butyllithium. The coupling reaction was continued for 30 min. The polymers were stabilized by a~ding 0.6%
by weight of 2,6 di-tert-butyl-p-cresol, isolated by means of steam coagulation and dried at sub-atmospheric pressure.
Preparation of copolymer BX
A stainless steel reaction vessel provided with a stirrer and having a capacity of 20 l was charged with 15 1 of cyclohexane and heated to a temperature o~
70 C. Then, a starting mixture of 3GO g of styrene and 575 g o~ butadiene was dissolved in the cyclohexane.
The copolymerization was initiated by addition of sec butyllithium (5.6 mmol), thus simultaneously titrating impurities and initiating the polymerization.
Ten minutes after the initiation followed a gradual addition of 125 g o~ butadiene over a period of 13 min, followed by allowing the mixture to polymerize for a further 28 min. Then, the active polymer chains were 2U terminated by addition o~ diethyl adipate in an amount stoichiometric with respect to the amount o~ sea~butyl-lithium. The coupling reaction was continued ~or 30 min. The polymers wer~ stabilized by adding 0.6~ by weight of 2,6-di-tert-butyl-p-cresol, isolated by means of steam coagulation and dried at sub-atmospheric pressure.
A few properties of polymer~ Al, Bl, B2, ~3, ~X, AY and BX are stat~d in Table l hereinafter. Table l ~hows that polymers Al, ~X and AY comply with the requirements o~ ~tyrene content, vinyl content and Tg o~ copoly~er A and that polym~rs B1, B2, B3 ~nd BY
comply with these thræe requirement~ for polymer B
which are pr~sent in the compositions according to the invention.
` 1326722 , u I ~ ~n r~ ~r m d~ I
~ I
~ ~, .~ ,~ , ~ .,~ I ~ ~ ~1 ~ o ~ ~r o .~, U~
~, .
I
,I
,,~ I
, ~ ~, .,, t , ,~
.,,, ~
,.................... ...
. ~, . ..
~,ooooooo o ~ , o o o o o o o U
e 0 I ~, o O O O O O
O IO O O C~ O ~ID O .C
I~ O ~) O OD i~ a~ 4 ~ O I~ r~ ~ ~ ~ ~1 S~ ~ I S~
I O
I ~
~ D ~ O ~ O
o~ I a ~ ~ I ~ o ~1 ~ I ~1 ~ h O O
3 ,~
:~t ~ I o _I O
,1 1 ~ O
o o o Q -- o ~ a) rl O ~
O ~ ~ ~ O O
U ~U I~1 -- O ~D OD ~ ~ /1) h ~ ~
h ~ ~ :~ t) V
o ~
I ~ x ~ x a ~
o I
i~4 1 ,1 ~ r~
i ;.
.
3~6722 Figures l and 2 of the accompanying drawing show a plot of perc~ntage differ~ntial styrene content in the polymer against total monomer conversion expressed in a percentage, the upper, dotted, line in Figure l relating to copolymer Al and the lower line to copolymers Bl and B3, and the lines in Figure 2 relating to copolymers AX, AY and BX.
It can be seen that copolymers Al, Bl ~nd B3 are true random copolymers having a constant average styrene content throughout the polymer molecule, i.e. the styrene content of successive incremental portions of the molecule is substantially co~stant throughout~ In contradistinction hereto, the styrene content of successive incrsmental portions of the molecule of copolymer AX become progressively larger, as shown in Eigure 2, copolymer AX not complying with the requirement of the differential content of styrene over the polymer chain which is less than ~ive percentage points, as determined by monomer conversion. It can also be seen that copolymers AY and BX do not comply with the latter requirement.
Examples l and 2 and Comparative Experiments A-E
Seven elastomeric compositions were produced from the polymers Al, Bl, B2, B3, AX, AY and BX and rom Dutrex 729 extender oil, using the weight ratio~ stated in Table 2. This table also states the Mooney viscosity of the mixtures. The elastomeric compositions contained 37.5 parts by weight of the extender oil on lO0 paxts by ; weight o~ polymer. Elastomeric compositions 1 and 2 are according ~o the pr~s~nt invention, elastomeric compositions 3-7 are not.
~326722 Table 2 Elastomeric Components andMooney composition weight ratioviscosity MLj(1+4~, 100 C
1 Bl/Al 60:40 33 2 B2/A1 70:30 47 3 B3/AX 60:40 41 4 BX/AX 60:40 46 BX/AY 60:40 43 6 B3/AY 60:40 36 7 BX/A1 60:40 43 Seven vulcanized elastomeric compositions were produced by using the elastomeric compositions 1-7 according to the compounding recipe shown in Tabla 3 and using optimum cure time at 160 C according to method ASTM D 2084.
~able 3 Ingredient Parts by weight Elastomeric composition 137.5 Zinç oxide 3.0 Stearic acid 2.0 Santoflex 13~ * 1.0 Carbon black ISAF N220 95.0 Dutrex 729~ 12~5 Sulphur 2.0 Santocure (CBS) 1.5 Analytical data on the seven vulcanized elastomexic composition are presented in Table 4. Examples 1 and 2 are according to the present invention, Comparative Experiments A-E are not.
~ ~R~
13~6722 C) O
o O h ~1 4~ ~
In O ~
r~
a ~ a) .,, O ~ ~ ~r o~ ~D ~ ~r 03 OD
rl ~q ~ ~ , , , ~ ~ CO C) .~ ~ O ~ ~ CO
O .
O ~ O C~ O O O O O
a) P~
U ~ r~ ,1 o~ ~ t~
E~ ~ o O U~ .
~ ~ O O O O O O O
_I rl o I
5~ ~ ,i ~ cn 1`
~ ~, U
., ~I S~
..
N a~ ~
z ~ 0 ~ ~ ~
O
: ~
~ ~ ~V~
t) ~ ~1 ~
~~ - -23- 63293-3005 Table 4 shows that the vulcanized elastomeric compositions obtained in Examples 1 and 2 possess a considerably lower Shore A hardness at minus 10 C, and therefore a correspon-dingly better winter performance, than those obtained in Comparative Experiments A-E. This considerable improvement is obtained whilst maintaining a low rolling resistance, a high wet grip performance and a high resistance against abrasion. Further-more, the vulcanized compositions of Comparative Experiments B-E
have a relatively high rolling restistance and those of ~ompar-ative Experiments B, C and D also have a relatively low wet gripperformance.
In Figures 3-6 of the accompanying drawing the values of tan ~ are plotted against the temperature in C, for Examples 1 and 2 and Comparative Experiments A and B, respectively. It can be seen that the tan 3 in Figures 3 and 4 show -a flat and broad maximum which indicates partial compatibility of polymers Bl and Al and of B2 and A:l. The tan ~ in Figure; 5 shows two peaks which indicates incompatibility of polymers B3 and AX and BX and AX respectively. Similar results for the tan ~ curves were obtained for Comparative Experiments C-E.
~ ~, U
., ~I S~
..
N a~ ~
z ~ 0 ~ ~ ~
O
: ~
~ ~ ~V~
t) ~ ~1 ~
~~ - -23- 63293-3005 Table 4 shows that the vulcanized elastomeric compositions obtained in Examples 1 and 2 possess a considerably lower Shore A hardness at minus 10 C, and therefore a correspon-dingly better winter performance, than those obtained in Comparative Experiments A-E. This considerable improvement is obtained whilst maintaining a low rolling resistance, a high wet grip performance and a high resistance against abrasion. Further-more, the vulcanized compositions of Comparative Experiments B-E
have a relatively high rolling restistance and those of ~ompar-ative Experiments B, C and D also have a relatively low wet gripperformance.
In Figures 3-6 of the accompanying drawing the values of tan ~ are plotted against the temperature in C, for Examples 1 and 2 and Comparative Experiments A and B, respectively. It can be seen that the tan 3 in Figures 3 and 4 show -a flat and broad maximum which indicates partial compatibility of polymers Bl and Al and of B2 and A:l. The tan ~ in Figure; 5 shows two peaks which indicates incompatibility of polymers B3 and AX and BX and AX respectively. Similar results for the tan ~ curves were obtained for Comparative Experiments C-E.
Claims (9)
1. An elastomeric composition suitable for use in the tread portion of a pneumatic tyre, said composition comprising:-(1) in the range of from 10 to 90% by weight of a copolymer A of a mono-aromatic vinyl compound and a conjugated diene and having a content of mono-aromatic vinyl compound in the range of from 10 to 40% by weight, a vinyl content in the conjugated diene units of at least 50% by weight, calculated on total conjugated diene units, and a glass transition temperature above minus 35 °C, and (2) in the range of from 90 to 10% by weight of a polymer B which is a homopolymer of a conjugated diene or a copolymer of a mono-aromatic vinyl compound and a conjugated diene, said polymer B
containing less than 25% by weight of mono-aromatic vinyl compound and having a vinyl content in the conjugated diene units of less than 25% and a glass transition temperature below minus 55 °C, said percentages by weight of copolymer A and polymer B
being calculated on the total of A and B, and copolymer A and polymer B, if present as a copolymer, having a differential content of the aromatic vinyl compound over the polymer chain which varies less than five percentage points; as determined by monomer conversion.
containing less than 25% by weight of mono-aromatic vinyl compound and having a vinyl content in the conjugated diene units of less than 25% and a glass transition temperature below minus 55 °C, said percentages by weight of copolymer A and polymer B
being calculated on the total of A and B, and copolymer A and polymer B, if present as a copolymer, having a differential content of the aromatic vinyl compound over the polymer chain which varies less than five percentage points; as determined by monomer conversion.
2. An elastomeric composition as claimed in claim 1 in which the differential content of the mono-aromatic vinyl compound over the polymer chain is less than two percentage points.
3. An elastomeric composition as claimed in claim 1 which contains in the range of from 20 to 50% by weight of copolymer A
and 80 to 50% by weight of polymer B.
and 80 to 50% by weight of polymer B.
4. An elastomeric composition as claimed in claim 1 in which the mono-aromatic vinyl compound is styrene and the conjugated diene is 1,3-butadiene.
5. An elastomeric composition as claimed in claim 1 in which at least a portion of copolymer A and of polymer B, if present as a copolymer, is a coupled copolymer, coupled by means of a coupling agent.
6. An elastomeric composition as claimed in claim 1 in which the glass transition temperature of copolymer A is in the range of from minus 25 °C to plus 25 °C and that of polymer B
below minus 65 °C.
below minus 65 °C.
7. A process for the preparation of an elastomeric composition as claimed in any one of claim 1 to claim 6 which process comprises mixing (1) in the range of from 10 to 90% by weight of a copolymer A of a mono-aromatic vinyl compound and a conjugated diene and having a content of aromatic vinyl compound in the range of from 10 to 40% by weight, a vinyl content in the conjugated diene units of at least 50% by weight, calculated on total conjugated diene units, and a glass transition temperature above minus 35 °C, and 25a (2) in the range of from 90 to 10% by weight of a polymer B
which is a homopolymer of a conjugated diene or a copolymer of a mono-aromatic vinyl compound and a conjugated diene, said polymer B containing less than 25% by weight of mono-aromatic vinyl compound and having a vinyl content in the conjuagated diene units of less than 25% and a glass transition temperature below minus 55°C.
which is a homopolymer of a conjugated diene or a copolymer of a mono-aromatic vinyl compound and a conjugated diene, said polymer B containing less than 25% by weight of mono-aromatic vinyl compound and having a vinyl content in the conjuagated diene units of less than 25% and a glass transition temperature below minus 55°C.
8. An unvulcanized elastomeric composition comprising a blend of an elastomeric composition as claimed in any one of claims 1 to 6 with vulcanization compounding ingredients.
9. A tyre whose tread has been formed by vulcanizing an elastomeric composition as claimed in claim 8.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8724437 | 1987-10-19 | ||
| GB878724437A GB8724437D0 (en) | 1987-10-19 | 1987-10-19 | Elastomeric compositions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1326722C true CA1326722C (en) | 1994-02-01 |
Family
ID=10625529
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000579219A Expired - Fee Related CA1326722C (en) | 1987-10-19 | 1988-10-05 | Elastomeric compositions, process for the preparation thereof and tyres containing them |
Country Status (13)
| Country | Link |
|---|---|
| US (2) | US5036138A (en) |
| EP (1) | EP0313164B1 (en) |
| JP (1) | JPH0781034B2 (en) |
| KR (1) | KR890006735A (en) |
| AT (1) | ATE91296T1 (en) |
| AU (1) | AU605370B2 (en) |
| BR (1) | BR8805378A (en) |
| CA (1) | CA1326722C (en) |
| DE (1) | DE3882196T2 (en) |
| ES (1) | ES2056905T3 (en) |
| GB (1) | GB8724437D0 (en) |
| PT (1) | PT88779B (en) |
| ZA (1) | ZA887718B (en) |
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| GB8918702D0 (en) * | 1989-08-16 | 1989-09-27 | Shell Int Research | Process for the preparation of random solution copolymers of conjugated dienes and vinyl aromatic compounds |
| JPH03119042A (en) * | 1989-09-30 | 1991-05-21 | Yokohama Rubber Co Ltd:The | Rubber composition for tire tread |
| FR2673187B1 (en) * | 1991-02-25 | 1994-07-01 | Michelin & Cie | RUBBER COMPOSITION AND TIRE COVERS BASED ON SAID COMPOSITION. |
| JP3553707B2 (en) * | 1994-11-30 | 2004-08-11 | 株式会社ブリヂストン | Pneumatic tire |
| DE69623083T2 (en) * | 1995-07-05 | 2003-04-30 | Bridgestone Corp | Rubber compound for tire tread |
| DE19613195A1 (en) * | 1996-04-02 | 1997-10-09 | Huels Chemische Werke Ag | Tire treads with low rolling resistance and improved ABS braking |
| US6429245B1 (en) | 1997-09-16 | 2002-08-06 | The Goodyear Tire & Rubber Company | Tire tread with elastomers of spatially defined Tg's |
| JP3845231B2 (en) | 1999-08-20 | 2006-11-15 | 本田技研工業株式会社 | Defect judgment method of injection mold |
| US6598637B2 (en) * | 2000-08-01 | 2003-07-29 | The Goodyear Tire & Rubber Company | Pneumatic tire having a rubber component containing a block styrene butadiene copolymer |
| US6420484B1 (en) * | 2000-09-29 | 2002-07-16 | The Goodyear Tire & Rubber Company | Asymmetrical tin-coupled rubbery polymers |
| US20040031548A1 (en) * | 2000-10-30 | 2004-02-19 | Angela Amaddeo | Method for improving the grip of a tyre on a snowy and/or icy road, and a winter tyre |
| JP3797166B2 (en) | 2001-09-18 | 2006-07-12 | 株式会社デンソー | Network system |
| US6956084B2 (en) * | 2001-10-04 | 2005-10-18 | Bridgestone Corporation | Nano-particle preparation and applications |
| KR100477229B1 (en) * | 2002-07-09 | 2005-03-18 | 한국타이어 주식회사 | Rubber for tire tread |
| JP4683928B2 (en) | 2002-12-18 | 2011-05-18 | 株式会社ブリヂストン | Clay exfoliation method, composition obtained from the method, and modified rubber containing the composition |
| US6875818B2 (en) | 2003-01-16 | 2005-04-05 | Bridgestone Corporation | Polymer nano-strings |
| US7205370B2 (en) * | 2004-01-12 | 2007-04-17 | Bridgestone Corporation | Polymeric nano-particles of flower-like structure and applications |
| US8465844B2 (en) * | 2004-02-13 | 2013-06-18 | Henkel Ag & Co. Kgaa | Elastic attachment adhesive containing radial block copolymer |
| US20050182194A1 (en) * | 2004-02-13 | 2005-08-18 | Qiwei He | Adhesive containing radial block copolymer |
| US8063142B2 (en) | 2004-03-02 | 2011-11-22 | Bridgestone Corporation | Method of making nano-particles of selected size distribution |
| US7112369B2 (en) * | 2004-03-02 | 2006-09-26 | Bridgestone Corporation | Nano-sized polymer-metal composites |
| US7718737B2 (en) | 2004-03-02 | 2010-05-18 | Bridgestone Corporation | Rubber composition containing functionalized polymer nanoparticles |
| US20050282956A1 (en) | 2004-06-21 | 2005-12-22 | Xiaorong Wang | Reversible polymer/metal nano-composites and method for manufacturing same |
| US7998554B2 (en) | 2004-07-06 | 2011-08-16 | Bridgestone Corporation | Hydrophobic surfaces with nanoparticles |
| US7249621B2 (en) * | 2004-07-29 | 2007-07-31 | The Goodyear Tire & Rubber Company | Rubber composition and tire with component of diene-based elastomer composition with corncob granule dispersion |
| US7441572B2 (en) * | 2004-09-17 | 2008-10-28 | The Goodyear Tire & Rubber Company | Pneumatic tire having a tread containing immiscible rubber blend and silica |
| US7572855B2 (en) | 2005-01-28 | 2009-08-11 | Bridgestone Corporation | Nano-composite and compositions manufactured thereof |
| US7579398B2 (en) | 2005-02-02 | 2009-08-25 | Bridgestone Corporation | Nano-composite and compositions therefrom |
| US7659342B2 (en) | 2005-02-03 | 2010-02-09 | Bridgestone Corporation | Polymer nano-particle with polar core and method for manufacturing same |
| US9061900B2 (en) | 2005-12-16 | 2015-06-23 | Bridgestone Corporation | Combined use of liquid polymer and polymeric nanoparticles for rubber applications |
| US7538159B2 (en) | 2005-12-16 | 2009-05-26 | Bridgestone Corporation | Nanoparticles with controlled architecture and method thereof |
| US7884160B2 (en) | 2005-12-19 | 2011-02-08 | Bridgestone Corporation | Non-spherical nanoparticles made from living triblock polymer chains |
| US8288473B2 (en) | 2005-12-19 | 2012-10-16 | Bridgestone Corporation | Disk-like nanoparticles |
| US8877250B2 (en) | 2005-12-20 | 2014-11-04 | Bridgestone Corporation | Hollow nano-particles and method thereof |
| US7560510B2 (en) | 2005-12-20 | 2009-07-14 | Bridgestone Corporation | Nano-sized inorganic metal particles, preparation thereof, and application thereof in improving rubber properties |
| US8697775B2 (en) | 2005-12-20 | 2014-04-15 | Bridgestone Corporation | Vulcanizable nanoparticles having a core with a high glass transition temperature |
| US7601772B2 (en) * | 2005-12-20 | 2009-10-13 | Bridgestone Corporation | Nano-composite and method thereof |
| US7935184B2 (en) | 2006-06-19 | 2011-05-03 | Bridgestone Corporation | Method of preparing imidazolium surfactants |
| EP2046575A4 (en) | 2006-07-28 | 2010-01-13 | Bridgestone Corp | Polymeric core-shell nanoparticles with interphase region |
| US7597959B2 (en) | 2006-12-19 | 2009-10-06 | Bridgestone Corporation | Core-shell fluorescent nanoparticles |
| US7649049B2 (en) | 2006-12-20 | 2010-01-19 | Bridgestone Corporation | Rubber composition containing a polymer nanoparticle |
| US7829624B2 (en) | 2007-06-29 | 2010-11-09 | Bridgestone Corporation | One-pot synthesis of nanoparticles and liquid polymer for rubber applications |
| ES2527600T3 (en) | 2008-12-31 | 2015-01-27 | Bridgestone Corporation | Procedure of formation of nanoparticles first forming the nucleus, nanoparticle and composition |
| US9062144B2 (en) | 2009-04-03 | 2015-06-23 | Bridgestone Corporation | Hairy polymeric nanoparticles with first and second shell block polymer arms |
| US9115222B2 (en) | 2009-12-29 | 2015-08-25 | Bridgestone Corporation | Well defined, highly crosslinked nanoparticles and method for making same |
| US9428604B1 (en) | 2011-12-30 | 2016-08-30 | Bridgestone Corporation | Nanoparticle fillers and methods of mixing into elastomers |
| US9441098B1 (en) * | 2015-11-18 | 2016-09-13 | The Goodyear Tire & Rubber Company | Tire with tread for low temperature performance and wet traction |
| US20200199334A1 (en) * | 2018-12-20 | 2020-06-25 | Dynasol Elastómeros, S.A. De C.V. | Dual Composition Block Copolymers |
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|---|---|---|---|---|
| NL145567B (en) * | 1970-04-16 | 1975-04-15 | Shell Int Research | PROCEDURE FOR THE NON-CONTINUOUS COPOLYMERIZATION OF CONJUGATED SERVICES WITH UP TO 5 C-ATOMS AND VINYLAROMATIC COMPOUNDS. |
| JPS56112947A (en) * | 1980-02-08 | 1981-09-05 | Japan Synthetic Rubber Co Ltd | Rubber composition |
| JPS56110753A (en) * | 1980-02-08 | 1981-09-02 | Bridgestone Corp | Rubber composition for tire |
| JPS5773030A (en) * | 1980-09-20 | 1982-05-07 | Bridgestone Corp | Rubber composition for tire |
| CA1196139A (en) * | 1982-02-26 | 1985-10-29 | Hiroshi Furukawa | Elastomer composition |
| US4526934A (en) * | 1982-03-19 | 1985-07-02 | Bridgestone Tire Company Limited | Branched styrene-butadiene copolymers and pneumatic tires using the same |
| JPS5945341A (en) * | 1982-09-09 | 1984-03-14 | Yokohama Rubber Co Ltd:The | Rubber composition for tire tread |
| JPS59140240A (en) * | 1983-01-31 | 1984-08-11 | Japan Synthetic Rubber Co Ltd | Rubber composition |
| JPH0717800B2 (en) * | 1985-01-09 | 1995-03-01 | 住友ゴム工業株式会社 | Rubber composition for tire tread |
| US4567225A (en) * | 1985-07-05 | 1986-01-28 | The Yokohama Rubber Co., Ltd. | Rubber composition for tire treads |
| JPS62143947A (en) * | 1985-12-19 | 1987-06-27 | Yokohama Rubber Co Ltd:The | Rubber composition for tire tread |
| JPS62190238A (en) * | 1986-02-18 | 1987-08-20 | Yokohama Rubber Co Ltd:The | Rubber composition for tire tread |
-
1987
- 1987-10-19 GB GB878724437A patent/GB8724437D0/en active Pending
-
1988
- 1988-10-05 CA CA000579219A patent/CA1326722C/en not_active Expired - Fee Related
- 1988-10-11 US US07/255,240 patent/US5036138A/en not_active Expired - Lifetime
- 1988-10-17 JP JP63261307A patent/JPH0781034B2/en not_active Expired - Lifetime
- 1988-10-17 PT PT88779A patent/PT88779B/en active IP Right Grant
- 1988-10-17 AU AU23932/88A patent/AU605370B2/en not_active Ceased
- 1988-10-17 ZA ZA887718A patent/ZA887718B/en unknown
- 1988-10-17 KR KR1019880013546A patent/KR890006735A/en not_active Application Discontinuation
- 1988-10-18 ES ES88202329T patent/ES2056905T3/en not_active Expired - Lifetime
- 1988-10-18 BR BR8805378A patent/BR8805378A/en not_active Application Discontinuation
- 1988-10-18 AT AT88202329T patent/ATE91296T1/en not_active IP Right Cessation
- 1988-10-18 DE DE88202329T patent/DE3882196T2/en not_active Expired - Fee Related
- 1988-10-18 EP EP88202329A patent/EP0313164B1/en not_active Expired - Lifetime
-
1991
- 1991-01-31 US US07/648,688 patent/US5064905A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| AU2393288A (en) | 1989-04-20 |
| ES2056905T3 (en) | 1994-10-16 |
| DE3882196D1 (en) | 1993-08-12 |
| US5064905A (en) | 1991-11-12 |
| EP0313164A2 (en) | 1989-04-26 |
| EP0313164B1 (en) | 1993-07-07 |
| ATE91296T1 (en) | 1993-07-15 |
| AU605370B2 (en) | 1991-01-10 |
| JPH01135845A (en) | 1989-05-29 |
| BR8805378A (en) | 1989-06-13 |
| EP0313164A3 (en) | 1991-11-06 |
| DE3882196T2 (en) | 1994-02-10 |
| ZA887718B (en) | 1989-06-28 |
| KR890006735A (en) | 1989-06-15 |
| JPH0781034B2 (en) | 1995-08-30 |
| US5036138A (en) | 1991-07-30 |
| PT88779B (en) | 1992-12-31 |
| GB8724437D0 (en) | 1987-11-25 |
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