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
  • B60C1/0016—Compositions of the tread
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F253/00—Macromolecular compounds obtained by polymerising monomers on to natural rubbers or derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F279/00—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00
  • C08F279/02—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00 on to polymers of conjugated dienes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F279/00—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00
  • C08F279/02—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00 on to polymers of conjugated dienes
  • C08F279/04—Vinyl aromatic monomers and nitriles as the only monomers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F285/00—Macromolecular compounds obtained by polymerising monomers on to preformed graft polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L15/00—Compositions of rubber derivatives
• • 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
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/18—Homopolymers or copolymers of hydrocarbons having four or more carbon atoms
  • C08L23/20—Homopolymers or copolymers of hydrocarbons having four or more carbon atoms having four to nine carbon atoms
  • C08L23/22—Copolymers of isobutene; Butyl rubber; Homopolymers or copolymers of other iso-olefins
• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/04—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to rubbers
• • 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

Definitions

• the present invention relates to a tire and to a crosslinkable elastomeric composition.
• the present invention relates to a tire, including at least one structural element obtained by crosslinking a crosslinkable elastomeric composition comprising at least one elastomeric polymer grafted with at least one phenolic resin.
• the present invention also relates to a crosslinkable elastomeric composition
• a crosslinkable elastomeric composition comprising at least one elastomeric polymer grafted with at least one phenolic resin, as well as to a crosslinked manufactured article obtained by crosslinking said crosslinkable elastomeric composition.
• resins such as, for example, novolak-type or resol- type phenolic resins.
• thermosetting resins in the polymeric base such as, for example, m-cresol-formaldehyde or phenolic resins, as described, for example, in the following Japanese
• Patent Applications JP 7-109381, JP 7-109382, or JP 7- 109383.
• United States Patent US 5,026,762 relates to a rubber composition for use in tire treads which comprises :
• a base rubber comprising a first rubber and a second rubber blended in a weight ratio of from 50:50 to 75:25, said first rubber containing natural rubber in an amount of at least 80% by weight, and said second rubber consisting essentially of a butadiene rubber;
• a carbon black having an iodine adsorption of from 90 to 200 mg/g and a dibutyl phthalate adsorption of from 100 to 140 ml/100 g;
• the abovementioned rubber composition for tire treads is said to be useful for all-weather tires and to have a sufficient resistance to snow and ice skidding, to abrasion, to cracking and to crack growth and adequate durability.
• United States Patent US 6,376,587 relates to a rubber composition for a tire tread comprising per 100 parts by weight of a diene based rubber component containing at least 50 parts by weight of styrene butadiene rubber: (1) 5 to 50 parts by weight of carbon black having a nitrogen absorption surface area of from 90 to 180 m 2 /g and a DBP absorption amount of from 100 to 170 ml/100 g; (2) 5 to 50 parts by weight of silica; (3) wherein the total amount of said carbon black and said silica is from 30 to 90 parts by weight; and (4) 5 to 20% by weight of a silane coupling agent relative to the blended amount of silica; (5) 1 to 15 parts by weight of a thermoplastic (novolak-type) phenolic resin; and (6) 5 to 20% by weight of hexamethylenetetramine relative to the blended amount of resin, wherein tan ⁇ at 60 0 C is lower than or equal to 0.14, tan ⁇ at 0
• the abovementioned rubber composition is said to reduce the rolling resistance and to improve the fuel consumption without impairing the braking performance and the turning performance of an automobile on a wet road surface.
• the Applicant has noticed that the use of the above disclosed phenolic resins in crosslinkable elastomeric compositions, may negatively affect their abrasion resistance. Consequently, the Applicant has faced the problem of providing a tire having high abrasion resistance combined with low rolling resistance.
• the Applicant has now found that it is possible to obtain a tire having the above reported properties by using a crosslinkable elastomeric compositions comprising at least one elastomeric polymer grafted with at least one phenolic resin.
• the tire so obtained shows high abrasion resistance combined with low rolling resistance. Furthermore, said tire show good mechanical properties (both static and dynamic) .
• the present invention relates to a tire comprising at least one structural element including a crosslinked elastomeric material obtained by crosslinking a crosslinkable elastomeric composition comprising a crosslinkable elastomeric base comprising at least 30 phr, preferably of from 50 phr to 100 phr, of at least one elastomeric polymer grafted with at least one phenolic resin.
• the grafting of said at least one phenolic resin onto said at least one elastomeric polymer may be determined according to known techniques such as, for example, by FTIR analysis or 1 H-NMR analysis: further details about said techniques will be disclosed in the examples which follow.
• said crosslinkable elastomeric base further comprises at least one second elastomeric polymer in an amount not higher than or equal to 70 phr, preferably of from 0 phr to 50 phr.
• crosslinkable elastomeric base means any polymer or polymers mixture, either natural or synthetic, capable of assuming all the chemical-physical and mechanical properties typical of elastomeric polymers as a result of crosslinking with system known in the art such as, for example, a sulfur-based system or a peroxide-based system.
• the term "phr" means the parts by weight of a given component of the elastomeric composition per 100 parts by weight of the elastomeric base .
• the tire comprises : a carcass structure of a substantially toroidal shape, having opposite lateral edges associated with respective right-hand and left-hand bead structures, said bead structures comprising at least one bead core and at least one bead filler; a belt structure applied in a radially external position with respect to said carcass structure; a tread band radially superimposed on said belt structure; a pair of sidewalls applied laterally on opposite sides with respect to said carcass structure; wherein said structural element is a tread band.
• the present invention also relates to a crosslinkable elastomeric composition
• a crosslinkable elastomeric composition comprising a crosslinkable elastomeric base comprising at least 30 phr, preferably of from 50 phr to 100 phr, of at least one elastomeric polymer grafted with at least one phenolic resin.
• the present invention also relates to a crosslinked manufactured article obtained by crosslinking a crosslinkable elastomeric composition above disclosed.
• said at least one phenolic resin is grafted directly onto the elastomeric polymer.
• said at least one phenolic resin is grafted onto the elastomeric polymer through at least one functional group .
• said crosslinkable elastomeric composition further comprises from 0 phr to 120 phr, preferably from 20 phr to 90 phr, of at least one carbon black reinforcing filler.
• said elastomeric polymer grafted with at least one phenolic resin may have a weight average molecular weight (M w ) not lower than 80,000, preferably of from 100,000 to 1,000,000.
• Said weight average molecular weight (M w ) may be determined according to known techniques such as, for example, by gel permeation chromatography (GPC) .
• said elastomeric polymer grafted with at least one phenolic resin may have a Mooney viscosity ML (1+4) not lower than 40, preferably of from 50 to 110.
• Said Mooney viscosity ML (1+4) may be determined according to Standard ASTM D1646-04 (at 100 0 C) .
• the phenolic resin may be introduced into the elastomeric polymer by means of processes known in the art such as, for example, the processes disclosed in United States Patents US 2,227,797, or US 4,105,610.
• said phenolic resin may be grafted onto the elastomeric polymer by means of a process comprising: - feeding at least one elastomeric polymer, said elastomeric polymer optionally containing at least one functional group, and at least one phenolic resin, into at least one extruder comprising: a housing including at least one feed opening and a discharge opening, and at least one screw rotatably mounted in said housing; mixing and softening said mixture so as to obtain an elastomeric polymer grafted with at least one phenolic resin,- - discharge the elastomeric polymer obtained in the above step through the discharge opening.
• said phenolic resin may be grafted onto said elastomeric polymer by means of a process comprising: - feeding at least one elastomeric polymer, at least one functionalized monomer, and at least one phenolic resin, into at least one extruder comprising: a housing including at least one feed opening and a discharge opening, and at least one screw rotatably mounted in said housing,- mixing and softening said mixture so as to obtain an elastomeric polymer grafted with at least one phenolic resin,- discharging the elastomeric polymer obtained in the above step through the discharge opening.
• said processes may be carried out at a temperature of from 20°C to 300 0 C, more preferably of from 80 0 C to 25O 0 C.
• said processes may be carried out for a time of from 10 seconds to 5 minutes, more preferably of from 30 seconds to 3 minutes.
• said extruder is a co-rotating twin- screw extruder.
• Said elastomeric polymer grafted with at least one phenolic resin may be obtained in the form of a continuous ribbon or, alternatively, in the form of a subdivided product .
• said at least one phenolic resin may be selected, for example, from: - novolak-type phenolic resins or resol-type phenolic resins obtained from the reaction of a phenolic compound such as, for example, phenol, alkyl substituted phenol, arylalkyl or alkylaryl substituted phenol, resorcinol, alkyl substituted resorcinol, arylalkyl or alkylaryl substituted resorcinol, or mixtures thereof, with an aldehyde such as, for example, formaldehyde, p-formaldehyde, butyraldheyde, benzaldehyde, salicylaldheyde, acetaldehyde, propionaldehyde, crotonaldehyde, butyraldehyde, iso-butyraldehyde, n-valeraldehyde, crotonaldehyde, cinnamald
• novolak-type phenolic resins or resol-type phenolic resins, which may be advantageously used according to the present invention are: octylphenol-formaldehyde resin, octylphenol- formaldehyde resin containing methylol groups, or mixture thereof .
• phenolic resins which may be used according to the present invention and are available commercially are the products known under the name of SP-1068, SP-1045, from Schenectady International.
• said at least one phenolic resin is preferably grafted onto the elastomeric polymer through at least one functional group.
• said at least one functional group may be selected, for example from: carboxylic groups; carboxylate groups; anhydride groups; ester groups, or mixtures thereof. Anhydride groups, carboxylic groups, are particularly preferred.
• the functional group may be introduced into the elastomeric polymer by means of processes known in the art such as, for example, during the production of the elastomeric polymer by co-polymerization with at least one corresponding functionalized monomer,- or by subsequent modification of the elastomeric polymer by grafting said at least one functionalized monomer, said grafting being optionally carried out in the presence of a free radical initiator (for example, an organic peroxide) .
• a free radical initiator for example, an organic peroxide
• said at least one functional group may be introduced into the elastomeric polymer by means of a process comprising: feeding at least one elastomeric polymer and at least one functionalized monomer into at least one extruder comprising: a housing including at least one feed opening and a discharge opening, and at least one screw rotatably mounted in said housing,- mixing and softening said mixture so as to obtain an elastomeric polymer including at least one functional group,- discharging the elastomeric polymer obtained in the above step through the discharge opening.
• Functionalized monomers which may be advantageously used include, for example, monocarboxylic or dicarboxylic acids, or derivatives thereof, in particular salts, anhydrides or esters.
• monocarboxylic or dicarboxylic acids or derivatives thereof are: maleic acid, fumaric acid, citraconic acid, itaconic acid, acrylic acid, methacrylic acid, dithiodisuccinic acid, dithiodipropionic acid, and salts, anhydrides or esters derived therefrom, or mixtures thereof.
• Maleic anhydride, dithiodipropionic acid are particularly preferred.
• the elastomeric polymer which may be utilized in the production of the elastomeric polymer grafted with at least one phenolic resin may be selected from those commonly used in sulfur-crosslinkable elastomeric compositions, that are particularly suitable for producing tires, that is to say from elastomeric polymers or copolymers with an unsaturated chain having a glass transition temperature (T 9 ) generally below 2O 0 C, preferably in the range of from O 0 C to -110 0 C.
• T 9 glass transition temperature
• polymers or copolymers may be of natural origin or may be obtained by solution polymerization, emulsion polymerization or gas-phase polymerization of one or more conjugated diolefins, optionally blended with at least one comonomer selected from monovinylarenes .
• the obtained polymers or copolymers contain said at least one comonomer selected from monovinylarenes in an amount of not more than 60% by weight.
• the conjugated diolefins generally contain from 4 to 12, preferably from 4 to 8 carbon atoms, and may be selected, for example, from the group comprising: 1,3- butadiene, isoprene, 2 , 3-dimethyl-l, 3-butadiene, 1,3- pentadiene, 1, 3-hexadiene, 3-butyl-l, 3-octadiene, 2-phenyl-1, 3 -butadiene, or mixtures thereof. 1,3- butadiene, isoprene, or mixtures thereof, are particularly preferred. Isoprene, 1, 3 -butadiene, are still particularly preferred.
• Monovinylarenes which may optionally be used as comonomers generally contain from 8 to 20, preferably from 8 to 12 carbon atoms, and may be selected, for example, from: stirene; 1-vinylnaphthalene; 2- vinylnaphthalene; various alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl derivatives of stirene such as, for example, ⁇ -methylstirene, 3-methylstirene, 4-propylstirene, 4-cyclohexylstirene, 4-dodecylstirene, 2-ethyl-4-benzylstirene, 4-p-tolylstirene, 4- (4- phenylbutyl) stirene, or mixtures thereof.
• stirene is particularly preferred.
• the elastomeric polymer may be selected, for example, from: cis-1 , 4-polyisoprene
• elastomeric polymer of one or more monoolefins with an olefinic comonomer and at least one diene, or derivatives thereof may be used.
• the monoolefins may be selected from: ethylene and ⁇ - olefins generally containing from 3 to 12 carbon atoms, such as, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, or mixtures thereof.
• ethylene and ⁇ - olefins generally containing from 3 to 12 carbon atoms, such as, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, or mixtures thereof.
• copolymers between ethylene and an ⁇ - olefin, optionally with a diene isobutene homopolymers or copolymers thereof with small amounts of a diene, which are optionally at least partially halogenated.
• the diene generally contains from 4 to 20 carbon atoms and is preferably selected from: 1, 3 -butadiene, isoprene, 1, 4-hexadiene, 1 , 4-cyclohexadiene, 5- ethylidene-2-norbornene, 5-methylene-2-norbornene, vinylnorbornene, or mixtures thereof.
• EPDM ethylene/propylene/diene copolymers
• polyisobutene butyl rubbers
• halobutyl rubbers in particular chlorobutyl or bromobutyl rubbers; or mixtures thereof .
• Elastomeric polymers functionalized by reaction with suitable terminating agents or coupling agents may also be used.
• elastomeric polymers obtained by anionic polymerization in the presence of an organometallic initiator may be functionalized by reacting the residual organometallic groups derived from the initiator with suitable terminating agents or coupling agents such as, for example, imines, carbodiimides, alkyltin halides, substituted benzophenones, alkoxysilanes or aryloxysilanes (see, for example, European Patent EP 451,604, or United States Patents US 4,742,124, or US 4,550,142).
• the crosslinkable elastomeric base may further comprises at least one second elastomeric polymer.
• Said elastomeric polymer may be selected, for example, from: cis-1 , 4-polyisoprene (natural or synthetic), 3,4- polyisoprene, polybutadiene (in particular polybutadiene with a high 1,4-cis content), optionally halogenated isoprene/isobutene copolymers, 1 , 3-butadiene/acrylonitrile copolymers, stirene/1, 3 -butadiene copolymers, stirene/isoprene/1, 3 -butadiene copolymers, stirene/1 , 3 -butadiene/acrylonitrile copolymers, or mixtures thereof; - ethylene/propylene copolymers (EPR) or ethylene/propylene/diene copolymers (EPDM) ; polyisobutene; butyl
• said crosslinkable elastomeric composition may further comprise at least one carbon black reinforcing filler.
• the carbon black reinforcing filler which may be used in the present invention may be selected from those having a surface area of not less than 20 m 2 /g (determined by CTAB absorption as described in Standard ISO 6810:1995) .
• At least one additional reinforcing filler may advantageously be added to the above disclosed crosslinkable elastomeric composition, in an amount generally of from 0 phr to 120 phr, preferably of from 20 phr to 90 phr.
• the reinforcing filler may be selected from those commonly used for crosslinked manufactured products, in particular for tires, such as, for example, silica, alumina, aluminosilicates, calcium carbonate, kaolin, or mixtures thereof.
• the silica which may be used in the present invention may generally be a pyrogenic silica or, preferably, a precipitated silica, with a BET surface area (measured according to Standard ISO 5794/1:2005) of from 50 m 2 /g to 500 m 2 /g, preferably of from 70 m 2 /g to 200 m 2 /g.
• the crosslinkable elastomeric composition may advantageously incorporate a silane coupling agent capable of interacting with the silica and of linking it to the elastomeric polymer during the vulcanization.
• said silane coupling agent may be selected, for example, from those having at least one hydrolizable silane group which may be identified, for example, by the following general formula (I) : (R) 3 Si-C n H 2n -X (I) wherein the groups R, which may be equal or different from each other, are selected from: alkyl, alkoxy or aryloxy groups or from halogen atoms, on condition that at least one of the groups R is an alkoxy or aryloxy group; n is an integer of from 1 to 6, extremes included; X is a group selected from: nitroso, mercapto, amino, epoxide, vinyl, imide, chloro, -(S) 1n C n H 2n -Si-(R) 3 , or -S-COR, wherein m and n are integers of from 1 to 6, extremes included, and the groups R are defined as above.
• silane coupling agents that are particularly preferred are bis (3-triethoxysilyl- propyl) tetrasulphide, bis (3-triethoxysilylpropyl) - disulphide, or mixtures thereof.
• Said coupling agents may be used as such or as a suitable mixture with an inert filler (for example, carbon black) so as to facilitate their incorporation into the crosslinkable elastomeric base.
• said silane coupling agent is present in the crosslinkable elastomeric composition in an amount of from 0 phr to 10 phr, preferably of from 0.5 phr to 5 phr.
• the crosslinkable elastomeric composition above disclosed may be vulcanized according to known techniques, in particular with sulfur-based vulcanizing systems commonly used for elastomeric polymers.
• a sulfur-based vulcanizing agent is incorporated together with vulcanization accelerators.
• the temperature is generally kept below 150 0 C and preferably below 13O 0 C, so as to avoid any unwanted pre-crosslinking phenomena.
• the vulcanizing agent most advantageously used is sulfur, or molecules containing sulfur (sulfur donors) , with accelerators and activators known to those skilled in the art .
• Activators that are particularly effective are zinc compounds, and in particular ZnO, ZnCO 3 , zinc salts of saturated or unsaturated fatty acids containing from 8 to 18 carbon atoms, such as, for example, zinc stearate, which are preferably formed in situ in the elastomeric composition from ZnO and fatty acid, and also BiO, PbO, Pb 3 O 4 , PbO 2 , or mixtures thereof.
• Accelerators that are commonly used may be selected, for example, from: dithiocarbamates, guanidine, thiourea, thiazoles, sulphenamides, thiurams, amines, xanthates, or mixtures thereof.
• Said crosslinkable elastomeric composition may comprise other commonly used additives selected on the basis of the specific application for which the composition is intended.
• antioxidants for example, the following may be added to said elastomeric composition: antioxidants, anti-ageing agents, plasticizers, adhesives, anti-ozone agents, modifying resins, waxes, fibres (for example Kevlar pulp), or mixtures thereof.
• a plasticizer generally selected from mineral oils, vegetable oils, synthetic oils, or mixtures thereof, such as, for example, aromatic oil, naphthenic oil, phthalates, soybean oil, or mixtures thereof, may be added to said crosslinkable elastomeric composition.
• the amount of plasticizer generally ranges from 0 phr to 70 phr, preferably from 3 phr to 30 phr.
• the above disclosed crosslinkable elastomeric composition may be prepared by mixing together the crosslinkable elastomeric base with the reinforcing filler and with the other additives optionally present according to techniques known in the art .
• the mixing may be carried out, for example, using an open mixer of open-mill type, or an internal mixer of the type with tangential rotors (Banbury) or with interlocking rotors (Intermix) , or in continuous mixers of Ko-Kneader type (Buss) , or of co-rotating or counter-rotating twin- screw type.
• Fig. 1 is a view in cross section of a portion of a tire made according to the invention
• Fig. 2 is a schematic diagram of a production plant for producing an elastomeric polymer grafted with at least one phenolic resin according to the process of the present invention.
• Fig. 1 shows only a portion of the tire, the remaining portion not represented being identical and symmetrically arranged with respect to the radial direction "r" .
• the tire (100) comprises at least one carcass ply
• the carcass ply (101) and the bead core (102) is achieved here by folding back the opposite lateral edges of the carcass ply (101) around the bead core (102) so as to form the so-called carcass back-fold (101a) as shown in Fig. 1.
• the conventional bead core (102) may ⁇ be replaced with at least one annular insert formed from rubberized wires arranged in concentric coils (not represented in Fig. 1) (see, for example, European Patent Applications EP 928,680, or EP 928,702).
• the carcass ply (101) is not back-folded around said annular inserts, the coupling being provided by a second carcass ply (not represented in Fig. 1) applied externally over the first.
• the carcass ply (101) generally consists of a plurality of reinforcing cords arranged parallel to each other and at least partially coated with a layer of a crosslinked elastomeric composition.
• These reinforcing cords are usually made of textile fibres, for example rayon, nylon or polyethylene terephthalate, or of steel wires stranded together, coated with a metal alloy (for example copper/zinc, zinc/manganese, zinc/molybdenum/cobalt alloys and the like) .
• the carcass ply (101) is usually of radial type, i.e. it incorporates reinforcing cords arranged in a substantially perpendicular direction relative to a circumferential direction.
• the core (102) is enclosed in a bead (103) , defined along an inner circumferential edge of the tire (100), with which the tire engages on a rim (not represented in Fig. 1) forming part of a vehicle wheel.
• the space defined by each carcass back- fold (101a) contains a bead filler (104) wherein the bead core (102) is embedded.
• a belt structure (106) is applied along the circumference of the carcass ply (101) .
• the belt structure is applied along the circumference of the carcass ply (101) .
• the belt structure is applied along the circumference of the carcass ply (101) .
• (106) comprises two belt strips (106a, 106b) which incorporate a plurality of reinforcing cords, typically metal cords, which are parallel to each other in each strip and intersecting with respect to the adjacent strip, oriented so as to form a predetermined angle relative to a circumferential direction.
• a plurality of reinforcing cords typically metal cords
• On the radially outermost belt strip (106b) may optionally be applied at least one zero-degree reinforcing layer (106c), commonly known as a "0° belt”, which generally incorporates a plurality of reinforcing cords, typically textile cords, arranged at an angle of a few degrees relative to a circumferential direction, and coated and welded together by means of a crosslinked elastomeric composition.
• a sidewall (108) is also applied externally onto the carcass ply (101) , this sidewall extending, in an axially external position, from the bead (103) to the end of the belt structure (106) .
• a tread band (109) which may be made according to the present invention, whose lateral edges are connected to the sidewalls (108) , is applied circumferentially in a position radially external to the belt structure (106) .
• the tread band (109) has a rolling surface (109a) designed to come into contact with the ground.
• Circumferential grooves which are connected by transverse notches (not represented in Fig. 1) so as to define a plurality of blocks of various shapes and sizes distributed over the rolling surface (109a) are generally made in this surface (109a) , which is represented for simplicity in Fig. 1 as being smooth.
• a tread underlayer (111) is placed between the belt structure (106) and the tread band (109) .
• the tread underlayer (111) may have uniform thickness.
• the tread underlayer (111) may have a variable thickness in the transversal direction.
• the thickness may be greater near its outer edges than at a central zone.
• said tread underlayer (111) extends over a surface substantially corresponding to the surface of development of said belt structure (106) .
• said tread underlayer (111) extends only along at least one portion of the development of said belt structure (106) , for instance at opposite side portions of said belt structure (106) (not represented in Fig. 1) .
• a strip made of elastomeric material (110) commonly known as a "mini-sidewall" may optionally be present in the connecting zone between the sidewalls
• this mini-sidewall generally being obtained by co-extrusion with the tread band and allowing an improvement in the mechanical interaction between the tread band (109) and the sidewalls (108) .
• the end portion of the sidewall (108) directly covers the lateral edge of the tread band (109) .
• the process for producing the tire according to the present invention may be carried out according to techniques and using apparatus that are known in the art, as described, for example, in European Patents EP 199,064, or in United States Patent US 4,872,822, or US 4,768,937, said process including manufacturing the crude tire and subsequently moulding and vulcanizing the crude tire.
• (200) includes an extruder (201) suitable for carrying out the process for the preparation of the elastomeric polymer grafted with at least one phenolic resin according to the present invention.
• the extruder (201) is fed with the compounds necessary for producing said grafted elastomeric polymer.
• the extruder is a co-rotating twin screw extruder.
• a previously made elastomeric polymer containing at least one functional group such as, for example, a functional group derived from maleic anhydride or dithiodipropionic acid
• a phenolic resin (203)
• the compounds may be fed to the extruder (201) through different feed hoppers (not represented in Fig. 2) .
• Each flow (202) and (203), is fed to the feed hopper (206) by means of different metering devices (205) .
• said metering devices are loss-in- weight gravimetric feeders.
• each flow is fed to the feed hopper (206) by means of different metering devices (205) .
• said metering devices are loss-in- weight gravimetric feeders.
• the phenolic resin (203) may be in a molten state and may be injected to the extruder (201) by means of a gravimetrically controlled feeding pump (not represented in Fig. 2) .
• the elastomeric polymer, the at least one functionalized monomer (such as, for example, maleic anhydride or dithiodipropionic acid) and the phenolic resin may be fed to the extruder (201) through a feed hopper (206) by means of a metering device (205) (not represented in Fig. 2) .
• Fig. 2 shows also a degassing unit schematically indicated by reference sign (208) from which a flow of the gases possibly generated during extrusion (207) exits .
• the resulting elastomeric polymer grafted with at least one phenolic resin (210) is discharged from the extruder (201), e.g. in the form of a continuous strand, by pumping it through an extruder die (209) and is conveyed to a cooling device (211) .
• a gear pump (not represented in Fig. 2) may be provided before said extruder die (209) .
• the resulting elastomeric polymer including at least one phenolic resin may be granulated by means of a grinding device (not represented in Fig. 2) .
• the elastomeric polymer grafted with at least one phenolic resin (210) is discharged from the extruder (201) in the form of a subdivided product by pumpimg it through an extruder die (209) which may be provided with a perforated die plate equipped with knives (not represented in Fig. 2) .
• the obtained subdivided product may be, e.g. in a granular form, with an average diameter of the granules generally of from 0.5 mm to about 3 mm, preferably of from 1 mm to 2 mm, and a length generally of from about 1 mm to 4 mm, preferably of from 1.5 mm to 3 mm.
• IR-g-MAH functionalized cis-1, 4-polyisoprene obtained as below disclosed; phenolic resin: octylphenol-formaldehyde resin (SP-1)
• Nizhnekamskneftechim Export was obtained in the form of granules having an average particles size diameter of about 3 mm - 20 mm, by means of a rubber grinder.
• the so obtained granules (100 phr) and maleic anhydride (2 phr) also in a granular form, were fed to the feed hopper of a co-rotating twin-screw extruder having a nominal screw diameter of 40 mm and a L/D ratio of 48.
• the maximum temperature in the extruder was 220 0 C.
• the extrusion head was kept at a temperature of 100 0 C.
• the obtained elastomeric polymer was discharged from the extruder in the form of a continuous strand, was cooled at room temperature (23 0 C) in a cooling device and granulated.
• a sample of the obtained elastomeric polymer was subjected to FTIR analysis below disclosed in order to evaluate the presence of the grafted maleic anhydride.
• a sample of the elastomeric polymer (0.5 g) was placed in a wire netting and compressed, at 15 tons, for 5 min, at 70 0 C, in a Carver Laboratory press, to obtain a supported thin layer of the elastomeric polymer. Subsequently, the obtained supported thin layer of the elastomeric polymer, was put in a ASE 100 Accelerated Solvent Extractor from Dionex in order to extract the non-grafted maleic anhydride. The extraction was carried out in an acetone solution, at a temperature of 120 0 C, at a pressure of 1500 psi, for a time of 20 min.
• the extracted elastomeric polymer was dissolved in a dichloromethane solution to obtain a viscous solution which was spread onto a sodium chloride lamina.
• the spread lamina was heated, at 5O 0 C, for 30 min, under vacuum, to obtain a supported thin film of the elastomeric polymer.
• the obtained elastomeric polymer was discharged from the extruder in the form of a continuous strand, was cooled at room temperature (23 0 C) in a cooling device and granulated.
• a sample of the obtained elastomeric polymer was subjected to FTIR analysis below disclosed in order to evaluate the presence of the grafted phenolic resin.
• FTIR analysis A sample of the elastomeric polymer (0.5 g) was placed in a wire netting and compressed, at 15 tons, for 5 min, at 7O 0 C, in a Carver Laboratory press, to obtain a supported thin layer of the elastomeric polymer. Subsequently, the obtained supported thin layer of the elastomeric polymer, was put in a ASE 100
• Accelerated Solvent Extractor from Dionex in order to extract the non-grafted phenolic resin.
• the extraction was carried out in an acetone solution, at a temperature of 120 0 C, at a pressure of 1500 psi, for a time of 20 min.
• the extracted elastomeric polymer was dissolved in a dichloromethane solution to obtain a viscous solution which was spread onto a sodium chloride lamina.
• the spread lamina which was heated, at 50°C, for 30 min, under vacuum, to obtain a supported thin layer of the elastomeric polymer.
• the elastomeric compositions given in Table 2 were prepared as follows (the amounts of the various components are given in phr) .
• accelerator (TBBS), retardant (PVI) , and sulfur were mixed together in an internal mixer (model Pomini PL 1.6) for about 5 min (1 st Step) . As soon as the temperature reached 145+5 0 C, the elastomeric composition was discharged. The accelerator (TBBS) , retardant (PVI) , and sulfur, were then added and mixing was carried out in an open roll mixer (2 nd Step) .
• Vulcan ® 1345 carbon black (Cabot Corp.); IR-g-MAH: functionalized cis-1, 4-polyisoprene obtained as disclosed in Example 1; Elastomeric polymer of Example 1: elastomeric polymer grafted with phenolic resin obtained as disclosed in Example 1 ; Wax: composition of microcrystalline wax (Antilux ®
• phenolic resin octylphenol- formaldehyde resin (SP-1068
• Polyplastol * 6 mixture of zinc salts of fatty acids (palmitic acid, stearic acid and oleic acid being present in major amount) (Great Lakes Chemical Corp . ) ; 6-PPD (antioxidant): N- (1, 3-dimethylbutyl) -N' -p- phenylenediamine; TMQ (anti-ageing): polymerized 2, 2 , 4-trimethyl-l, 2- dihydroquinoline (Vulcanox ® HS/LG - Lanxess) ; TBBS (accelerator) : N-t-butyl-2-benzothiazyl- sulfenamide (Vulkacit 8 NZ/ECG - Lanxess) ;
• Table 3 also shows the dynamic mechanical properties, measured using an Instron dynamic device in the traction-compression mode according to the following methods.
• Tan delta value is calculated as a ratio between viscous modulus (E") and elastic modulus (E') .
• Table 3 also show the DIN abrasion: the data (expressed in mm 3 ) correspond to the amount of elastomeric composition removed by operating under the standard conditions given in DIN standard 53516.
• SBR-g-MAH functionalized solution styrene/1,3- butadiene copolymer obtained as below disclosed;
• phenolic resin octylphenol-formaldehyde resin
• S-SBR-g-MAH The preparation of S-SBR-g-MAH was carried out as disclosed in Example 1 above reported, the only differences being the following: solution styrene/1 , 3 -butadiene copolymer having a styrene content of 36% by weight and a vinyl content of 27.5% by weight, with respect to the total copolymer weight, and containing 37.5 phr of aromatic oil (HP752 - Japan Synthetic Rubber) : 100 phr; maleic anhydride: 3 phr; extrusion head: kept at a temperature of 8O 0 C.
• a sample of the obtained elastomeric polymer was subjected to FTIR analysis below disclosed in order to evaluate the presence of the grafted maleic anhydride.
• a sample of the elastomeric polymer (0.5 g) was placed in a wire netting and compressed, at 15 tons, for 5 min, at 70 0 C, in a Carver Laboratory press, to obtain a supported thin layer of the elastomeric polymer. Subsequently, the obtained supported thin layer of the elastomeric polymer, was put in a ASE * 100
• Accelerated Solvent Extractor from Dionex in order to extract the non-grafted maleic anhydride.
• the extraction was carried out in a toluene :ethanol (30:70) solution, at a temperature of 130 0 C, at a pressure of 1500 psi, for a time of 20 min.
• the extracted elastomeric polymer was dissolved in a dichloromethane solution to obtain a viscous solution which was spread onto a sodium chloride lamina.
• the spread lamina was heated, at 50 0 C, for 30 min, under vacuum, to obtain a supported thin layer of the elastomeric polymer.
• a sample of the elastomeric polymer (0.5 g) was placed in a wire netting and compressed, at 15 tons, for 5 min, at 70°C, in a Carver Laboratory press, to obtain a supported thin layer of the elastomeric polymer. Subsequently, the obtained supported thin layer of the elastomeric polymer, was put in a ASE 100 Accelerated Solvent Extractor from Dionex in order to extract the non-grafted phenolic resin. The extraction was carried out in a toluene :ethanol (30:70) solution, at a temperature of 13O 0 C, at a pressure of 1500 psi, for a time of 20 min.
• the extracted elastomeric polymer was dissolved in a dichloromethane solution to obtain a viscous solution which was spread onto a sodium chloride lamina.
• the spread lamina was heated, at 50 0 C, for 30 min, under vacuum, to obtain a supported thin layer of the elastomeric polymer.
• the obtained supported thin layer of the elastomeric polymer was subjected to FTIR analysis which was carried out by means of a Perkin-Elmer Spectrum One FTIR Spectrometer.
• the elastomeric compositions given in Table 5 were prepared as follows (the amounts of the various components are given in phr) .
• S-SBR solution styrene/l , 3 -butadiene copolymer having a styrene content of 36% by weight and a vinyl content of 27.5% by weight, with respect to the total copolymer weight and containing 37.5 phr of aromatic oil (HP752 - Japan Synthetic Rubber) ;
• STR20 natural rubber (SRI Trang Agroindustry) ;
• BR polybutadiene (Europrene Neocis - Polimeri Europa) ;
• HV 3396 carbon black (Columbian);
• S-SBR-g-MAH functionalized solution styrene/1,3- butadiene copolymer obtained as disclosed in Example 5;
• Elastomeric polymer of Example 5 elastomeric polymer grafted with a phenolic resin obtained as disclosed in Example 5 ;
• X50S ⁇ silane coupling agent comprising 50% by weight of carbon black and 50% by weight of bis (3-triethoxysilylpropyl) tetrasulphide (Degussa-
• Zeosil ⁇ MP 1165 silica (Rhodia) ; Wax: composition of microcrystalline wax (Antilux ®
• TMQ anti-ageing: polymerized 2, 2 , 4-trimethyl-l, 2- dihydroquinoline (Vulcano ⁇ ⁇ HS/LG - Lanxess) ; phenolic resin: octylphenol-formaldehyde resin (SP-1068
• 6-PPD antioxidant: N- (1 , 3-dimethylbutyl) -N' -p- phenylenediamine;
• CBS (accelerator) : N-cyclohexyl-2-benzothiazyl- sulphenamide (Vulkacit * CZ/C - Lanxess) ; DPG80 (accelerator) : diphenyl guanidine (Rhenogran ®
• the dynamic mechanical properties are expressed in terms of dynamic elastic modulus (E') and Tan delta (loss factor) values.
• the Tan delta value is calculated as a ratio between viscous modulus (E") and elastic modulus (E') .
• Table 6 also show the DIN abrasion: the data (expressed in mm 3 ) correspond to the amount of elastomeric composition removed by operating under the standard conditions given in DIN standard 53516.
• SBR-g-MAH functionalized solution styrene/l, 3- butadiene copolymer obtained as below disclosed; phenolic resin: octylphenol-formaldehyde resin containing methylol groups (SP-1045 - Schenectady International) .
• S-SBR-g-MAH The preparation of the S-SBR-g-MAH was carried as disclosed in Example 1 above reported, the only- differences being the following: solution styrene/l , 3 -butadiene having a styrene content of 25% by weight and a vinyl content of 47% by weight, with respect to the total copolymer weight, and containing 37.5 phr of TDAE oil (SE).
• S-SBR solution styrene/1, 3 -butadiene copolymer, having a styrene content of 25% by weight and a vinyl content of 47% by weight, with respect to the total copolymer weight, and containing 37.5 phr of TDAE oil (SE SLR-4630 - Dow Chemical) ;
• STR20 natural rubber (SRI Trang Agroindustry) ;
• BR polybutadiene (Europrene Neocis - Polimeri Europa) ;
• HV 3396 carbon black (Columbian);
• S-SBR-g-MAH functionalized solution styrene/1,3- butadiene copolymer obtained as disclosed in Example 9;
• Elastomeric polymer of Example 9 elastomeric polymer grafted with a phenolic resin obtained as disclosed in Example 9;
• X50S ⁇ silane coupling agent comprising 50% by weight of carbon black and 50% by weight of bis (3-triethoxysilylpropyl) tetrasulphide (Degussa-
• Zeosil e MP 1165 silica (Rhodia) ; Wax: composition of microcrystalline wax (Antilux
• TMQ anti-ageing: polymerized 2 , 2 , 4-trimethyl-l, 2- dihydroquinoline (Vulcanox ® HS/LG - Lanxess) ; phenolic resin: octylphenol-formaldehyde resin containing methylol groups (SP-1045 - Schenectady
• 6-PPD antioxidant: N- (1, 3-dimethylbutyl) -N' -p- phenylenediamine ; CBS (accelerator) : N-cyclohexyl-2-benzothiazyl- sulphenamide (Vulkacit CZ/C - Lanxess) ;
• DPG80 (accelerator) : diphenyl guanidine (Rhenogran ® DPG80 - Rhein Chemie) .
• S-SBR-g-DTDP functionalized solution styrene/1,3- butadiene copolymer obtained as below disclosed;
• phenolic resin octylphenol-formaldehyde resin (SP-1068
• S-SBR-g-DTDP The preparation of S-SBR-g-DTDP was carried out as disclosed in Example 1 above reported, the only differences being the following: solution styrene/1, 3 -butadiene copolymer having a styrene content of 36% by weight and a vinyl content of 27.5% by weight, with respect to the total copolymer weight, and containing 37.5 phr of aromatic oil (HP752 - Japan Synthetic Rubber) : 100 phr; dithiodipropionic acid: 3 phr; maximum temperature in the extruder: 180 0 C; extrusion head: kept at a temperature of 80 0 C. A sample of the obtained elastomeric polymer was subjected to 1 H-NMR analysis below disclosed in order to evaluate the presence of the grafted dithiodipronic acid .
• solution styrene/1, 3 -butadiene copolymer having a styrene content of 36% by
• a sample of the elastomeric polymer (0.5 g) was placed in a wire netting and compressed, at 15 tons, for 5 min, at 70 0 C, in a Carver Laboratory press, to obtain a supported thin layer of the elastomeric polymer. Subsequently, the obtained supported thin layer of the elastomeric polymer, was put in a ASE ® 100 Accelerated Solvent Extractor from Dionex in order to extract the non-grafted phenolic resin. The extraction was carried out in a toluene rethanol (30:70) solution, at a temperature of 130 0 C, at a pressure of 1500 psi, for a time of 20 min.
• the extracted elastomeric polymer was dissolved in a dichloromethane solution and subsequently treated with a diazomethane in order to perform the esterification (methylation) of the acid group.
• the elastomeric compositions given in Table 11 were prepared as follows (the amounts of the various components are given in phr) .
• S-SBR solution styrene/1 , 3 -butadiene copolymer having a styrene content of 36% by weight and a vinyl content of 27.5% by weight, with respect to the total copolymer weight, and containing 37.5 phr of aromatic oil (HP752 - Japan Synthetic Rubber) ;
• STR20 natural rubber (SR Trang Agroindustry) ;
• BR polybutadiene (Europrene Neocis - Polimeri Europa) ;
• HV 3396 carbon black (Columbian);
• S-SBR-g-DTDP functionalized solution styrene/1,3- butadiene copolymer obtained as disclosed in Example 13;
• Polyplastol 0 6 mixture of zinc salts of fatty acids (palmitic acid, stearic acid and oleic acid being present in major amount) (Great Lakes Chemical
• Zeosil 1165 silica (Rhodia) ;
• Wax composition of microcrystalline wax (Antilux" 654 - Lanxess) ;
• TMQ anti-ageing: polymerized 2 , 2 , 4-trimethyl-l, 2- dihydroquinoline (Vulcanox * HS/LG - Lanxess) ; phenolic resin: octylphenol-formaldehyde resin (SP-1068
• DPG80 (accelerator) :diphenyl guanidine (Rhenogran ® DPG80 - Rhein Chemie) .

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