Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L21/00—Compositions of unspecified rubbers
• • 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
  • B60C1/0025—Compositions of the sidewalls
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/26—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers modified by chemical after-treatment
  • C08L23/28—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers modified by chemical after-treatment by reaction with halogens or halogen-containing compounds
  • C08L23/283—Iso-olefin halogenated homopolymers or copolymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2312/00—Crosslinking
• • 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
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T152/00—Resilient tires and wheels
  • Y10T152/10—Tires, resilient
  • Y10T152/10495—Pneumatic tire or inner tube
  • Y10T152/10765—Characterized by belt or breaker structure
  • Y10T152/1081—Breaker or belt characterized by the chemical composition or physical properties of elastomer or the like

Definitions

• the present invention relates to compositions for making tire sidewalls and other rubber constructions which exhibit improved ozone resistance and fatigue crack propagation resistance, as well as a reduction in staining and discoloration.
• the composition comprises a blend of halogenated copolymer of isoolefin and para-alkylstyrene of relatively high aromatic comonomer content and relatively low halogen content with general purpose rubbers (GPR) such as butadiene rubber (BR), natural rubber (NR) and/or isoprene rubber (IR).
• GPR general purpose rubbers
• BR butadiene rubber
• NR natural rubber
• IR isoprene rubber
• the tire sidewall may comprise a single layer or a veneer construction wherein an outer layer comprises the blend of the halogenated copolymer with one or more general purpose rubbers, and an inner layer can comprise a blend of general purpose rubbers
• Rubber tires such as pneumatic tires, include many components, such as, for example, sidewalls.
• Sidewalls are continuously subjected to distortion under normal road operating conditions
• the sidewalls are subjected to extensive continuous flexing and can crack under such conditions
• sidewalls are also subjected to atmospheric chemical action such as ozone attack
• the overall effect is that the sidewalls may erode and degrade The sidewall may even separate from the tire carcass during use, leading to tire failure
• U.S. Patent 5,376,438 to Costemalle et al. discloses multi-layer tire sidewalls having an outer layer prepared from a blend of halogenated isomonoolefin/para-alkylstyrene copolymer and general purpose rubbers.
• the inner layer comprises general purpose rubber.
• the sidewalls are said to exhibit good ozone resistance and fatigue crack resistance as well as a reduction in staining and discoloration.
• the halogen content of the halogenated isoolefin/para- alkylstyrene copolymers generally varied proportionately with the para-alkylstyrene content, e.g. higher para-methylstyrene content was used to get a higher halogen content. If the copolymer was excessively halogenated, some undesirable dihalo benzylic substitution would occur. Thus, excess para-methylstyrene was usually used. In tire sidewall compositions of the prior art, a relatively high bromine level was needed to achieve adhesion and ozone resistance, but such high bromination levels led to relatively tight cures and crack propagation.
• the invention is a blend of rubber and a brominated copolymer of an isoolefin and a para-alkylstyrene
• the copolymer comprises at least 9.5 but less than 20 weight percent of aromatic monomers (styrenics), and at least 0.2 but less than 1 mole percent para-bromoalkylstyrene.
• the blend preferably comprises from 35 to 65 phr of the copolymer, and from 35 to 65 phr of the general purpose rubber
• the styrenics can include para-alkylstyrene, brominated para-alkylstyrene, alpha-methylstyrene, brominated alpha- methylstyrene or combinations thereof
• the isoolefin is preferably isobutylene, whereas the para-alkylstyrene is preferably para-methylstyrene and the para-bromoalkylstyrene is preferably para-bromomethylstyrene
• the general purpose rubber can be a natural rubber, styrene-butadiene rubber, polybutadiene rubber and combinations thereof
• the copolymer preferably comprises from 12 to
• the invention provides a tire sidewall comprising a layer of the blend described above
• the blend can also be used in a veneered tire sidewall wherein an outer layer comprises the blend described above, and an inner layer comprises a highly unsaturated rubber or blend of unsaturated rubbers
• the invention provides an improvement in a tire sidewall comprising at least an outer layer comprising a blend of a copolymer of an isoolefin and a para-alkylstyrene and an unsaturated rubber, and an inner layer optionally comprising a highly saturated rubber or blend of unsaturated rubbers
• the copolymer comprises from 9 5 to 20 weight percent aromatic monomers and from 0 2 to 1 0 mole percent para-bromoalkylstyrene
• the blend contains quantities of bromoalkylstyrene and para- alkylstyrene which satisfy the following formula
• X [l 91 - (0 094 x Y)] ⁇ 0 1
• "X" is mole percent bromoalkylstyrene and "Y” is weight percent para- alkylstyrene (between the proposed limits of 9.5 to 20 weight percent).
• " ⁇ 0.1" as used herein indicates that the value X may be any number within the range of 0.1 above to 0.1 below [1.91 - (0.094 x Y)].
• the bromoalkylstyrene is preferably para-bromomethylstyrene and the para-alkylstyrene is preferably para- methylstyrene.
• the blend of the present invention has 0.96 mole percent para-bromomethylstyrene and 10 weight percent para-methylstyrene.
• the blend of the present invention preferably has 0.84 mole percent para-bromomethylstyrene and 12.5 weight percent para-methylstyrene.
• the polymerized para-alkylstyrene comonomer unit is characterized by the formula:
• R and R 1 are independently selected from the group consisting of hydrogen, alkyl groups having from 1 to about 5 carbon atoms, and primary and secondary alkyl halides having from 1 to about 5 carbon atoms, and ⁇ ' is selected from the halogen group consisting primarily of bromine, chlorine and mixtures thereof.
• halogenated para-alkylstyrene unit is shown as being pendant from the isoolefin polymer chain, represented by the wavy lines in the formula.
• the tire sidewall composition and layers of the present invention can be compounded by methods generally known in the art, such as by mixing with the uncured polymers various fillers such as titanium dioxide; carbon black, when black sidewalls are desired, or non-black fillers and pigments; extenders such as rubber process oils; curing aids such as zinc oxide, sulfur; accelerators or retarders and other additives such as antioxidants and antiozonants.
• various fillers such as titanium dioxide; carbon black, when black sidewalls are desired, or non-black fillers and pigments
• extenders such as rubber process oils
• curing aids such as zinc oxide, sulfur
• accelerators or retarders and other additives such as antioxidants and antiozonants.
• the invention in one embodiment involves the construction of a multi- layered tire sidewall, the outer layer of which comprises a blend of a copolymer of an isoolefin and para-alkylstyrene with one or more unsaturated rubbers (GPR).
• the sidewall also comprises one or more layers constructed from conventional sidewall compositions such as those discussed in "The Vanderbilt Rubber Handbook” pp 605 (1990)
• the outer layer of the sidewall is fabricated from a blend composition comprising at least one highly unsaturated rubber selected from the group consisting of natural rubber, SBR rubber, polyisoprene and polybutadiene rubber, and a halogenated copolymer of an isoolefin and a para-alkylstyrene unit
• the halogenated copolymer comprises about 35 to 65 parts, for example, 40 parts
• the unsaturated rubber desirably comprises from 35 to 65 parts natural rubber and/or polybutadiene rubber
• the outer layer blend may also optionally include from about 1 to about 90 preferably from about 5 to about 20 parts per hundred of ethylene-propylene-diene rubber (EPDM)
• the highly unsaturated rubber component of the outer layer may consist of a blend or mixture of two or more highly unsaturated rubbers These optional rubbers may also contain aromatic monomers to improve their compatibility When white sidewalls are desired, particularly preferred outer layer compositions comprise the halogenated para-
• the highly unsaturated rubbers are selected from the group consisting of natural rubbers, polyisoprene rubbers, styrene butadiene rubber (SBR) and polybutadiene rubber and mixtures thereof
• the natural rubbers are selected from the group consisting of Malaysian rubber such as SMR CV, SMR 5, SMR 10, SMR 20, and SMR 50 and mixtures thereof, wherein the natural rubbers have a
• Mooney viscosity at 100° C (ML 1+4) of about 30 to about 120, more preferably about 40 to about 65 Comparable Indonesian rubbers, with SIR pre-fixes, may also be used
• the Mooney viscosity test referred to herein is in accordance with ASTM D-1646 The Mooney viscosity of the polybutadiene rubber as measured at 100° C
• EPDM is the ASTM designation for a terpolymer of ethylene, propylene and a non-conjugated diolefin In such terpolymers the ethylene and propylene form a fully saturate backbone of methylene linkages with the non-conjugated diolefin, e.g.
• the EPDM elastomers thus contain a fully saturated backbone which provides outstanding resistance to oxidation, ozone, and cracking, as well as excellent low temperature flexibility.
• the Mooney viscosity of the EPDM terpolymer as measured at 125° C is about 20 to 80, more preferably about 25 to 75 and most preferably about 40 to about 60
• the ethylene content of the EPDM terpolymers may range from about 20 to about 90 weight percent, preferably from about 30 to about 85, more preferably from about 35 to about 80 weight percent.
• the total diene monomer content in the EPDM terpolymers may suitably range from about 0.1 to about 15 weight percent, preferably from about 0 5 to about 12 weight percent.
• the non-conjugated dienes may be straight chain or cyclic hydrocarbon diolefins having from 6 to 15 carbon atoms, such as dicyclopentadiene, including 5- methylene-2-norbornene, 5-vinyl-2-norbornene, 2-methylnorbornadiene, 2, 4- dimethyl-2,7-octadiene, 1,4-hexadiene and 5-ethylidene-2-norbornene
• the more preferred compounds include 5-methylene-2-norbornene, dicyclopentadiene, 1,4- hexadiene and 5-ethyliene, dicyclopenta-diene, 1,4-hexadiene and 5-ethylidene-2- norbornene
• a preferred EPDM terpolymer is VISTALON® 6505 manufactured by Exxon Chemical Company.
• butyl rubber as employed herein is intended to refer to a vulcanizable rubbery copolymer containing, by weight, from about 85 to 99.5% combined isoolefin having from 4 to 8 carbon atoms Such copolymers and their preparation are well known
• the butyl rubber may be halogenated by means known in the art.
• the Mooney viscosity of the halobutyl rubbers useful in the instant invention are measured at 125 ° C (ML 1+4) range from about 20 to about 80, more preferably about 25 to about 55, and most preferably about 30 to about 50.
• Suitable halogen-containing copolymers of a C to C isomonoolefin and a para-alkylstyrene for use as a component of the present blends and tire sidewall compositions comprise at least 9 5 weight percent of the para-alkylstyrene moiety.
• the para-alkylstyrene moiety may range from about 9.5 weight percent to about 20 weight percent, preferably from about 12 to about 17 weight percent of the copolymer
• the halogenated content of the copolymers may range from about 0.2 to about 1.0 mole percent, preferably from about 0.4 to about 0.8 mole percent.
• the halogen may be bromine, chlorine and mixtures thereof.
• the halogen is bromine.
• the major portion of the halogen is chemically bound to the para-alkyl group, that is, the halogen-containing copolymer comprises para-haloalkyl groups.
• the copolymers of the isomonoolefin and para-alkylstyrene useful to prepare the halogen-containing copolymers suitable as a component of the tire sidewall composition of the present invention include copolymers of isomonoolefin having from 4 to 7 carbon atoms and a para-alkylstyrene, such as those described in U.S. Pat. No. 5,162,445
• the preferred isomonoolefin comprises isobutylene.
• the preferred para-alkylstyrene comprises para-methylstyrene
• Other aromatic monomers and styrenics for example, alkylstyrenes such as alpha-methylstyrene and meta-methylstyrene, may be employed in lieu of some of the para-alkylstyrene, provided the total aromatic content of the copolymer is in the rage of 9.5 to 20 weight percent, preferably 12 to 17 weight percent.
• Sufficient amounts of the para-alkylstyrene must, of course, be used to obtain the halogenated copolymer with the halogenated para-alkyl groups.
• the blend of the present invention contains quantities of bromoalkylstyrene and para-alkylstyrene which satisfy the following formula:
• X is mole percent bromoalkylstyrene and "Y” is weight percent para- alkylstyrene (between the limits of 9 5 to 20 weight percent).
• "+ 0 1" as used herein indicates that the value X may be any number within the range of 0 1 above to 0.1 below [1 91 - (0 094 x Y)]
• the bromoalkylstyrene is preferably para- bromomethylstyrene and the para-alkylstyrene is preferably para-methylstyrene More preferably, the blend of the present invention has 0 96 mole percent para- bromomethyl styrene and 10 weight percent para-methylstyrene. Alternatively, the blend of the present invention preferably has 0.84 mole percent para- bromomethylstyrene and 12.5 weight percent para-methylstyrene.
• Suitable copolymers of an isomonoolefin and a para-alkylstyrene include copolymers having a weight average molecular weight (Mw) of at least about
• copolymers 100,000, preferably at least about 300,000, and a number average molecular weight (Mn) of at least about 100,000.
• the copolymers also, preferably, have a ratio of weight to number average molecular weight, i e , Mw/Mn of less than about 6 preferably less than about 4
• the brominated copolymer of the isoolefin and para-alkylstyrene obtained by the polymerization of these particular monomers under certain specific polymerization conditions now permits one to produce copolymers which comprise the direct reaction product (that is, in their as- polymerized form), and which have unexpectedly homogeneous uniform compositional distributions
• the copolymers suitable for the practice of the present invention can be produced These copolymers, as determined by gel permeation chromatography (GPC) demonstrate narrow molecular weight distributions and substantially homogeneous compositional distributions, or compositional uniformity over the entire range of compositions thereof At least about 95 weight percent
• halogen-containing copolymers useful in the practice of the present invention have a substantially homogenous compositional distribution and include the para-alkylstyrene moiety represented by the formula:
• R and R 1 are independently selected from the group consisting of hydrogen, alkyl preferably having from 1 to 5 carbon atoms, primary haloalkyl, secondary haloalkyl preferably having from 1 to 5 carbon atoms, and mixtures thereof and X is selected from the group consisting of bromine, chlorine and mixtures thereof, such as those disclosed in U.S. Pat. No. 5, 162,445, the teachings of which are incorporated by reference.
• the polymerization is carried out continuously in a typical continuous polymerization process using a baffled tank-type reactor fitted with an efficient agitation means such as a turbo mixer or propeller, and draft tube, external cooling jacket and internal cooling coils or other means of removing the heat of polymerization, inlet pipes for monomers, catalyst and diluents, temperature sensing means and an effluent overflow to a holding drum or quench tank.
• the reactor is purged of air and moisture and charged with dry, purified solvent or a mixture of solvent prior to introducing monomers and catalysts.
• Reactors which are typically used in butyl rubber polymerization are generally suitable for use in polymerization reaction to produce the desired para- alkylstyrene copolymers suitable for use in the present invention.
• the polymerization temperature may range from about minus 35° C to about minus
• 100° C preferably from about minus 40° to about minus 80° C.
• the processes for producing the copolymers can be carried out in the form of a slurry of polymer formed in the diluents employed, or as a homogeneous solution process.
• a slurry process is, however, preferred, since in that case, lower viscosity mixtures are produced in the reactor and slurry concentrations of up to 40 weight percent of polymer are possible.
• a solution process is preferred for the higher levels of PMS.
• the copolymers of isomonoolefins and para-alkylstyrene may be produced by admixing the isomonoolefin and the para-alkylstyrene in a copolymerization reactor under copolymerization conditions in the presence of a diluent and a Lewis acid catalyst.
• Typical examples of the diluents which may be used alone or in a mixture include propane, butane, pentane, cyclopentane, hexane, toluene, heptane, isooctane, etc., and various halohydrocarbon solvents which are particularly advantageous herein, including methylene chloride, chloroform, carbon tetrachloride, and methyl chloride, with methyl chloride being particularly preferred.
• an important element in producing the copolymer is the exclusion of the impurities from the polymerization reactor, namely, impurities which if present, will result in complexing with the catalyst or copolymerization with the isomonoolefins or the para-alkylstyrene, which in turn will prevent one from producing the para- alkylstyrene copolymer product useful in the practice of the present invention.
• impurities include the catalyst poisons, moisture and the like. These impurities should be kept out of the system.
• the para- alkylstyrene be at least 95 0 weight percent pure, preferably 97 5 weight percent pure, most preferably 99.5 weight percent pure, that the isomonoolefin be at least 99.5 weight percent pure, preferably at least 99 8 weight percent pure, and that the diluents employed be at least 99 weight percent pure, and preferably at least 99 8 weight percent pure
• the most preferred Lewis acid catalysts are ethyl aluminum dichloride and preferably mixtures of ethyl aluminum dichloride with diethyl aluminum chloride
• the amount of such catalysts employed will depend on the desired molecular weight and the desired molecular weight distribution of the copolymer being produced, but will generally range from about 20 ppm to 1 weight percent and preferably from about 0 001 to 0 2 weight percent based upon the total amount of monomer to be polymerized
• Halogenation of the polymer can be carried out in the bulk phase (e g melt phase) or either in solution or in a finely dispersed slurry
• Bulk halogenation can be effected in an extruder, or other internal mixer, suitably modified to provide adequate mixing and for handling the halogen and corrosive by-products of the reaction
• Suitable solvents for solution halogenation include the low boiling hydrocarbons (C 4 to C 7 ) and halogenated hydrocarbons Since the high boiling point para-methylstyrene makes its removal by conventional distillation impractical, and since it is difficult to completely avoid solvent halogenation, it is very important where solution or slurry halogenation is to be used that the diluent and halogenation conditions be chosen to avoid diluent halogenation, and that residual para-methylstyrene has been reduced to an acceptable level
• radical bromination of the enchained para- methylstyryl moiety in the useful copolymers for the practice of this invention can be made highly specific with almost exclusive substitution occurring on the para- methyl group, to yield the desired benzylic bromine functionality
• the specificity of the bromination reaction can thus be maintained over a broad range of reaction conditions, provided, however, the factors which would promote the ionic reaction route are avoided (i e , polar diluents, Friedel-Crafts catalysts, etc )
• solutions of the suitable para-methylstyrene/isobutylene copolymers in hydrocarbon solvents such as pentane, hexane or heptane can be selectively brominated using light, heat, or selected radical initiators (according to conditions, i.e., a particular radical initiator must be selected which has an appropriate half-life for the particular temperature condition being utilized, with generally longer half- lives preferred at warmer halogenation temperatures) as promoters of radical
• This reaction can be initiated by formation of a bromine atom, either photochemically or thermally (with or without the use of sensitizers), or the radical initiator used can be one which preferentially reacts with a bromine molecule rather than one which reacts indiscriminately with bromine atoms, or the solvents or polymer (i e , via hydrogen abstraction)
• the sensitizers referred to are those photochemical sensitizers which will themselves absorb lower energy photons and disassociate, thus causing in turn, disassociation of the bromine, including materials such as iodine It is, thus, preferred to utilize an initiator which has a half life of between about 0 5 and 2500 minutes under the desired reaction conditions, more preferably about 10 to 300 minutes
• the amount of initiator employed will usually vary between 0 02 and 1 percent by weight on the copolymer, preferably between about 0 02 and 0 3 percent
• the preferred initiators are bis azo compounds such as azo bis isobutyronitrile (AIBN
• radical initiators can also be used, but it is preferred to use a radical initiator which is relatively poor at hydrogen abstraction, so that it reacts preferentially with the bromine molecules to form bromine atoms rather than with the copolymer or solvent to form alkyl radicals. In those cases, there would then tend to be resultant copolymer molecular weight loss, and promotion of undesirable side reactions, such as crosslinking.
• the radical bromination reaction of the copolymers of para-methylstyrene and isobutylene is highly selective, and almost exclusively produces the desired benzylic bromine functionality.
• any desired amount of benzylic bromine functionality in the monobromo form can be introduced into the above stated copolymers, up to about 60 mole percent of the para- methylstyrene content.
• the para-methylstyrene content should preferably be at least twice the desired para-bromomethylstyrene content to avoid dibromination.
• the termination reactions be minimized during bromination, so that long, rapid radical chain reactions occur, and so that many benzylic bromines are introduced for each initiation, with a minimum of the side reactions resulting from termination.
• system purity is important, and steady-state radical concentrations must be kept low enough to avoid extensive recombinations and possible crosslinking.
• the reactions must also be quenched once the bromine is consumed, so that continued radical production with resultant secondary reactions (in the absence of bromine) do not then occur. Quenching may be accomplished by cooling, turning off the light source, adding dilute caustic, the addition of a radical trap, or combinations thereof.
• HBr Since one mole of HBr is produced for each mole of bromine reacted with or substituted on the enchained para-methylstyryl moiety, it is also desirable to neutralize or otherwise remove this HBr during the reaction, or at least during polymer recovery in order to prevent it from becoming involved in or catalyzing undesirable side reactions.
• neutralizations and removal can be accomplished with a post-reaction caustic wash, generally using a molar excess of caustic on the HBr.
• neutralization can be accomplished by having a particulate base (which is relatively nonreactive with bromine) such as calcium carbonate powder present in dispersed form during the bromination reaction to absorb the
• HBr as it is produced. Removal of the HBr can also be accomplished by stripping with an inert gas (e.g., N 2 ) preferably at elevated temperatures
• the brominated, quenched, and neutralized para-methylstyrene/isobutylene copolymers can be recovered and finished using conventional means with appropriate stabilizers being added to yield highly desirable and versatile functional saturated copolymers
• halogenation to produce a copolymer useful in the present invention is preferably accomplished by halogenating an isobutyl ene-para- methylstyrene copolymer using bromine in a normal alkane (e.g , pentane, hexane or heptane) solution utilizing a bis azo initiator, e g , AIBN or VAZO® 52 2,2'- azobis(2,4-dimethyl-pentane nitrile), at about 55° to 80° C, for a time period ranging from about 4 5 to about 30 minutes, followed by a caustic quench
• the halogen content is generally controlled by limiting the quantity of halogen reactant
• the recovered polymer is washed in basic water and water/isopropanol washes, recovered, stabilized and dried
• the aromatic halomethyl groups permit facile crosslinking to be accomplished in a variety of ways, for example, either directly through the halomethyl group or by conversion to other functional groups, as indicated above, to permit the desired crosslinking reactions to be employed
• Direct crosslinking can be effected with a variety of polyfunctional groups, as indicated above, to permit the desired crosslinking reactions to be employed
• Direct crosslinking can be effected with a variety of polyfunctional nucleophilic reagents such as ammonia, amines, or polyamines, metal dicarboxylates, metal dithiolates, promoted metal oxides (e.g , ZnO+zinc stearates and/or dithiocarbamates), etc
• Crosslinking can also be effected via polyalkylation reactions
• the aromatic halomethyl groups thus provide a wide choice of crosslinking reactions which can be used
• Various fillers can also be used in single layer or the outer and/or inner layer blend compositions of the present invention, and these include a
• the outer layer thickness may vary from about 0 8 mm to about 2.0 mm
• the inner layer may vary from about 1 0 mm to about 2.0 mm.
• a tire size 185/60-HR-14 would have a sidewall width of about 95 mm and an overall length of about 1210 mm
• the single-layer or multi-layered tire sidewall compositions of the present invention may be vulcanized by subjecting them to heat and/or light or radiation according to any vulcanization process
• the single-layer or multi-layered tire sidewall of the present invention may be used as the sidewall for motor vehicle tires such as truck tires, bus tires, passenger automobile, motorcycle tires and the like
• Suitable tire sidewall layer compositions may be prepared by using conventional mixing techniques including, e g , kneading, roller milling, extruder mixing, internal mixing (such as with a Banbury® mixer), etc
• the sequence of mixing and temperatures employed are well known to the skilled rubber compounder, the objective being the dispersion of fillers, activators and curatives in the polymer matrix without excessive heat buildup
• a useful mixing procedure utilizes a Banbury mixer in which the rubber components, fillers, and plasticizer are added and the composition mixed for the desired time to a particular temperature to achieve adequate dispersion of the ingredients.
• the rubbers and a portion of the fillers e.g., one-third to two-thirds
• is mixed for a short time e.g.
• Tires are generally built on a drum from at least three layers, namely, an outer layer comprising a tread portion and sidewalls comprising the inner and outer layers of this invention, an intermediate layer, and an innerliner. After the uncured tire has been built on a building drum, the uncured tire may be placed in a heated mold to shape it and heat it to vulcanization temperatures and, thereby, to produce a cured unitary tire from the multi-layers.
• Vulcanization of the molded tire typically, is carried out in heated presses under conditions well known to those skilled in the art.
• Curing time will be affected by the thickness of the tire to be molded and the concentration and type of curing agent as well as the halogen content of the halogenated copolymer.
• the vulcanization parameters can readily be established with a few experiments utilizing, e.g., a laboratory characterization device well known in the art, the Monsanto Oscillating Disc Cure Rheometer
• Tires produced according to the present invention offer black or white sidewall tire with the features of improved adhesion and ozone resistance as well as good curing and flex crack resistance.
• the present tire by using the halogenated copolymer in the tire sidewall, or in only the outer layer, good ozone resistance is achieved.
• the outer layer acts as a barrier preventing migration of additives in protectants from the inner layer to the outside, thus eliminating the staining and discoloring problem discussed above
• Test compositions were compounded using 3 -pass mixing conditions to blend the master batch components and the cure additives listed in Table 2 The compositions were cured at 150° C (18 minutes for tensile and fatigue testing, 21 minutes for Demattia and outdoor flex testing and 175° C (1 1 minutes for tensile and fatigue testing, 14 minutes for Demattia and outdoor flex testing)
• test compositions (1 A through IH) were tested for cure characteristics, tensile strength, flex fatigue, adhesion and ozone resistance The results are presented in Table 3 below The following descriptors are used herein to refer to cracking types and ratings
• Blends ID through IH exhibited similar cure characteristics to blends 1A, IB and IC and similar tensile properties Blends ID and IF had better fatigue-to-failure and flex crack propagation resistance, and comparable ozone resistance
• Blends of rubber with a high-bromine, low para-methylstyrene copolymer and a low-bromine, high para-methylstyrene copolymer were prepared at varying ratios The high-bromine, low para-methylstyrene copolymer was
• EXXPRO 93-4 copolymer comprised of 7 5 weight percent para-methylstyrene and 1 2 mole percent benzylic bromine It had a Mooney viscosity ML (1+8) at 125° C of 38 ⁇ 5
• the low-bromine, high para-methylstyrene copolymer (Copolymer 2) was comprised of 13 6 weight percent para-methylstyrene and 0 56 mole percent benzylic bromine (0 78 weight percent bromine) It has a Mooney viscosity ML (1 + 8) at 125° C of 37 ⁇ 5
• the blends were compounded as described in Example 1 and cured at 180° C for 15 minutes The blends had the compositions of Table 4
• Test compositions were compounded to blend the master batch components and the cure additives listed in Table 7 Three-pass mixing conditions were used for samples 1W, IX and 1Y Two-pass mixing conditions were used for sample 1Z
• BUDENETM 1207 is a trademarked butadiene rubber available from Goodyear
• FLEXON 641 is a naphthenic petroleum oil
• FLEXON 815 is a paraffinic petroleum oil.
• test compositions (IW through IZ) were tested for cure characteristics, tensile strength, flex fatigue, adhesion and ozone resistance The results are presented in Table 8
• Blends IX and 1Y exhibited superior outdoor flex and ozone resistance over blends IW and IZ
• the test compositions (IW through IZ) were used to re-side tires Tests were conducted on the tires to measure wear and ozone resistance The results are presented in Table 9 TABLE 9
• Blends IX and 1 Y exhibited superior wear characteristics to blends IW and IZ. Blends IX and 1Y also exhibited superior ozone resistance over blends IW and IZ.

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Tires In General (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Priority Applications (5)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26723027

Family Applications (1)

Country Status (12)

Cited By (7)

Families Citing this family (20)

Citations (4)

Family Cites Families (10)

• 1998
  • 1998-05-01 CN CN98804856A patent/CN1255150A/zh active Pending
  • 1998-05-01 ES ES98920115T patent/ES2186155T3/es not_active Expired - Lifetime
  • 1998-05-01 US US09/071,105 patent/US6374889B1/en not_active Expired - Fee Related
  • 1998-05-01 WO PCT/US1998/008863 patent/WO1998050464A1/en not_active Ceased
  • 1998-05-01 PL PL98336595A patent/PL336595A1/xx unknown
  • 1998-05-01 KR KR1019997010189A patent/KR20010012239A/ko not_active Withdrawn
  • 1998-05-01 JP JP54825498A patent/JP2002512652A/ja not_active Ceased
  • 1998-05-01 BR BR9808741-0A patent/BR9808741A/pt not_active Application Discontinuation
  • 1998-05-01 CA CA002286725A patent/CA2286725A1/en not_active Abandoned
  • 1998-05-01 EP EP98920115A patent/EP0981581B1/en not_active Expired - Lifetime
  • 1998-05-01 DE DE69810101T patent/DE69810101T2/de not_active Expired - Fee Related
  • 1998-05-04 TW TW087106858A patent/TW434151B/zh active
• 2002
  • 2002-01-02 US US10/040,778 patent/US6837288B2/en not_active Expired - Fee Related

Patent Citations (4)

Also Published As

Similar Documents

Legal Events