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WO2002062594A1 - Procede de fabrication de pneumatiques, pneumatiques obtenus par ce procede et compositions elastomeres utilisees selon ce procede - Google Patents

Procede de fabrication de pneumatiques, pneumatiques obtenus par ce procede et compositions elastomeres utilisees selon ce procede Download PDF

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Publication number
WO2002062594A1
WO2002062594A1 PCT/EP2002/001109 EP0201109W WO02062594A1 WO 2002062594 A1 WO2002062594 A1 WO 2002062594A1 EP 0201109 W EP0201109 W EP 0201109W WO 02062594 A1 WO02062594 A1 WO 02062594A1
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WO
WIPO (PCT)
Prior art keywords
epoxidized
process according
elastomeric polymer
tyre
composition according
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.)
Ceased
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PCT/EP2002/001109
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English (en)
Inventor
Marco Nahmias Nanni
Antonio Serra
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pirelli and C SpA
Pirelli Tyre SpA
Original Assignee
Pirelli Pneumatici SpA
Pirelli SpA
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Filing date
Publication date
Priority claimed from EP01102664A external-priority patent/EP1231079B1/fr
Application filed by Pirelli Pneumatici SpA, Pirelli SpA filed Critical Pirelli Pneumatici SpA
Priority to BR0206932-6A priority Critical patent/BR0206932A/pt
Priority to JP2002562579A priority patent/JP2004522620A/ja
Priority to US10/467,295 priority patent/US20040102557A1/en
Publication of WO2002062594A1 publication Critical patent/WO2002062594A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • C08L13/00—Compositions of rubbers containing carboxyl groups
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
    • 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
    • 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
    • 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
    • C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
    • C08C19/00—Chemical modification of rubber
    • C08C19/30—Addition of a reagent which reacts with a hetero atom or a group containing hetero atoms of the macromolecule
    • C08C19/34—Addition of a reagent which reacts with a hetero atom or a group containing hetero atoms of the macromolecule reacting with oxygen or oxygen-containing groups
    • C08C19/36—Addition of a reagent which reacts with a hetero atom or a group containing hetero atoms of the macromolecule reacting with oxygen or oxygen-containing groups with carboxy radicals
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/24—Acids; Salts thereof
    • 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
    • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
    • C08L63/08—Epoxidised polymerised polyenes

Definitions

  • the present invention relates to a process for producing tyres for vehicle wheels, to the tyres thus obtained and to the crosslinkable elastomeric compositions used therein. More particularly, the present invention relates to a process for producing tyres for vehicle wheels, which can be carried out in substantial absence of conventional crosslinking agents, to the tyres thus obtained and to the crosslinkable compositions used therein.
  • Processes for vulcanizing diene elastomers with sulphur are widely used in the rubber industry for the production of a wide range of products, and in particular tyres for vehicle wheels.
  • Implementation of these processes although giving high-quality vulcanized products, shows a considerable complexity, mainly due to the fact that, to obtain optimum vulcanization within industrially acceptable times, it is necessary to use a complex vulcanizing system which includes, besides sulphur or sulphur-donating compounds, one or more activators (for example stearic acid, zinc oxide and the like) and one or more accelerators (for example thiazoles, dithiocarbamates, thiurams, guanidines, sulphenamides and the like) .
  • activators for example stearic acid, zinc oxide and the like
  • accelerators for example thiazoles, dithiocarbamates, thiurams, guanidines, sulphenamides and the like
  • elastomeric compositions i.e. compositions which do not require the use of crosslinking agents such as sulphur or sulphur compounds
  • crosslinking agents such as sulphur or sulphur compounds
  • US patent 2,724,707 describes elastomeric compositions consisting of a diene polymer containing carboxylic groups, in particular a carboxylated nitrile rubber (XNBR) obtained by partial hydrolysis of a butadiene/acrylonitrile copolymer, wherein a polyhydric metal oxide (for example zinc oxide) is dispersed. On heating these compositions, they crosslink according to a mechanism of ionic type.
  • XNBR carboxylated nitrile rubber
  • the crosslinking reaction implies the formation of ester bonds between the epoxide groups and carboxylic groups.
  • the rheometric curves would show absence of reversion, stability of the crosslinked structure and a high crosslinking degree.
  • Italian patent IT-1,245,551 describes self- crosslinking compositions containing an epoxidized elastomer and a crosslinking agent of formula R1-R-R2, wherein R is an arylene, alkylene or alkenylene group, while Rl and R2 are carboxylic, amine, sulphonic or chlorosulphonic groups. Dicarboxylic or polycarboxylic acids, or mixtures thereof, can be used as crosslinking agents.
  • Self-crosslinking compositions containing an epoxidized elastomer and a second elastomer wherein the repeating units of the polymer chain contain at least one carboxylic group are also described.
  • self- crosslinking compositions are obtained by mixing an epoxidized elastomer (for example the products ENR 25 or ENR 50 which are available under the brand name Epoxiprene® from Guthrie Symington Ltd) with a butadiene/ acrylic acid copolymer (for example a product sold by Polysar/Bayer under the brand name Krynac®) .
  • ENR 25 or ENR 50 which are available under the brand name Epoxiprene® from Guthrie Symington Ltd
  • a butadiene/ acrylic acid copolymer for example a product sold by Polysar/Bayer under the brand name Krynac®
  • US patent 5,173,557 describes self-crosslinking compositions comprising an elastomeric polymer functionalized with isocyanate groups and a compound containing at least two active hydrogen atoms of Zerewitinoff type, or self-crosslinking compositions comprising an elastomeric polymer containing active hydrogen atoms of Zerewitinoff type and a compound containing at least two isocyanate groups.
  • an elastomeric polymer containing either isocyanate groups or active hydrogens of Zerewitinoff type can be used, without using an additional crosslinking agent.
  • the active hydrogen atoms can be present, for example, on hydroxide, amine, carboxylic or thiol groups.
  • the isocyanate groups are blocked beforehand with suitable functional groups, which are removed by heating before the crosslinking reaction between the free isocyanate groups and the active hydrogens, optionally with the aid of a catalyst.
  • the self-crosslinking compositions proposed hitherto in the prior art do not provide a valid alternative to conventional compositions vulcanized with sulphur or derivatives thereof.
  • the reason for this is that the performance qualities of the crosslinked products are generally unsatisfactory, in particular for applications such as tyre rubber compounds, wherein a substantial constancy of the elastic performance qualities over a wide range of working temperatures and at the same time high abrasion resistance without unacceptably increasing hardness is required.
  • crosslinked products and in particular tyres for vehicle wheels, which have the desired combination of properties can be produced in the substantial absence of additional crosslinking agents, by using self-crosslinking compositions comprising a mixture of at least an elastomeric polymer containing carboxylic groups, at least a liquid organic compound containing epoxide groups located internally on the molecule, and at least an oxide or an inorganic salt of a metal selected from Fe, Cu, Sn, Mo and Ni .
  • compositions After heating, these compositions achieve a high degree of crosslinking without addition of conventional crosslinking agents, with crosslinking times contained within limits which are acceptable for industrial use.
  • the resulting crosslinked product combines excellent mechanical and elastic performance qualities (in particular stress at break, elongation at break) so as to make the self-crosslinking compositions above particularly suitable as elastomeric materials to be used for the production of tyres, in particular tread bands.
  • liquid compounds containing internal epoxide groups makes it possible to obtain crosslinkable compositions which have excellent processability and a high capacity to include reinforcing fillers, even in the absence of compatibilizing additives, since these epoxidized products act not only as crosslinking agents but also as processing coadjuvants and are capable of interacting with reinforcing fillers containing active hydroxyl groups (for example silica), thus favouring compatibilization with the polymer matrix.
  • active hydroxyl groups for example silica
  • the present invention thus relates to a process for producing tyres for vehicle wheels, the said process comprising the following steps: manufacturing a green tyre comprising at least one crosslinkable elastomeric material; subjecting the green tyre to moulding in a mould cavity defined in a vulcanization mould; crosslinking the elastomeric material by heating the tyre to a predetermined temperature and for a predetermined time; characterized in that the crosslinkable elastomeric material comprises: (a) at least an elastomeric polymer containing carboxylic groups, (b) at least an epoxidized liquid organic compound containing epoxide groups located internally on the molecule, and (c) at least an oxide or an inorganic salt of a metal selected from Fe, Cu, Sn, Mo and Ni , the said crosslinking step being carried out substantially in the absence of additional crosslinking agents.
  • the crosslinking step is carried out by heating the crosslinkable elastomeric material to a temperature of at least 120°C for a time of at least 3 minutes, preferably to a temperature of from 130°C to 230°C for a time of from 5 to 90 minutes.
  • the said crosslinkable elastomeric material also comprises a reinforcing filler.
  • the present invention relates to a tyre for vehicle wheels comprising one or more components made of a crosslinked elastomeric material, characterized in that at least one of the said components comprises, as crosslinked elastomeric material, at least an elastomeric polymer containing carboxylic groups crosslinked by reaction with at least an epoxidized liquid organic compound containing epoxide groups located internally on the molecule in the presence of at least an oxide or an inorganic salt of a metal selected from Fe, Cu, Sn, Mo and Ni, wherein the said carboxylated elastomeric polymer is crosslinked substantially in the absence of additional crosslinking agents.
  • the present invention relates to a tyre for vehicles, comprising a belt structure extended coaxially around a carcass structure and a tread band extended coaxially around the belt structure and having an external rolling surface intended to come into contact with the ground, characterized in that the said tread band comprises at least an elastomeric polymer containing carboxylic groups crosslinked by reaction with at least an epoxidized liquid organic compound containing epoxide groups located internally on the molecule in the presence of at least an oxide or an inorganic salt of a metal selected from Fe, Cu, Sn, Mo and Ni, wherein the said carboxylated elastomeric polymer is crosslinked substantially in the absence of additional crosslinking agents.
  • the present invention relates to a crosslinkable elastomeric composition
  • a crosslinkable elastomeric composition comprising: (a) at least an elastomeric polymer containing carboxylic groups; (b) at least a liquid organic compound containing epoxide groups located internally on the molecule, and (c) at least an oxide or an inorganic salt of a metal selected from Fe, Cu, Sn, Mo and Ni ; the said composition being crosslinkable in substantial absence of any additional crosslinking agents.
  • the present invention relates to a crosslinked elastomeric product obtained by crosslinking a crosslinkable composition as defined above.
  • a crosslinkable composition as defined above.
  • the expression "in substantial absence of any additional crosslinking agents” means that the crosslinkable composition is not subjected to the action of other systems capable of bringing about its crosslinking, or that other products which may be present in the composition can in themselves participate in the crosslinking reaction, but are used in amounts less than the minimum amount required to obtain an appreciable degree of crosslinking in short times (for example within 5 minutes) .
  • compositions according to the present invention are crosslinkable in substantial absence of any of the crosslinking systems commonly used in the art, such as, for example, sulphur or sulphur donors, peroxides or other radical initiators, and neither are these compositions subjected to the action of high-energy radiation (UV, gamma rays, etc.) so as to induce crosslinking phenomena in the polymer.
  • crosslinking systems commonly used in the art, such as, for example, sulphur or sulphur donors, peroxides or other radical initiators, and neither are these compositions subjected to the action of high-energy radiation (UV, gamma rays, etc.) so as to induce crosslinking phenomena in the polymer.
  • liquid organic compounds containing epoxide groups located internally on the molecule are products of hydrocarbon type which are, at room temperature, in the form of viscous liquids or oils.
  • These compounds contain at least two internal epoxide groups, i.e. groups wherein one oxirane bridge connects:
  • the presence of internal epoxide groups does not, however, exclude the possibility of epoxide groups in a terminal position also being present in the molecule. At least two internal epoxide groups are present in the liquid organic compounds according to the present invention.
  • the amount of epoxide groups is such that the epoxide equivalent weight of the epoxidized compound is usually between 40 and 2,000, preferably between 50 and 1,500, more preferably between 100 and 1,000.
  • EW epoxide equivalent weight
  • %0 is the content of oxirane oxygen, expressed as a percentage by weight of oxirane oxygen relative to the total weight of the compound.
  • the content of oxirane oxygen in the epoxidized compounds can be determined according to known techniques, for example by titration with a solution of hydrobromic acid in acetic acid.
  • liquid organic compounds containing internal epoxide groups which are particularly preferred is that of epoxidized oils, which can be obtained by epoxidation of unsaturated fatty acids or esters (in particular glycerides, diglycerides or triglycerides) of unsaturated fatty acids, of synthetic or natural origin, or alternatively by epoxidation of mixtures of the said unsaturated acids or esters with saturated acids or esters thereof.
  • the saturated or unsaturated fatty acids generally contain from 10 to 26 carbon atoms, preferably from 14 to 22 carbon atoms.
  • Examples of unsaturated fatty acids are: myristoleic acid, palmitoleic acid, oleic acid, gadoleic acid, erucic acid, ricinoleic acid, linoleic acid, linolenic acid, arachidonic acid and the like, or mixtures thereof.
  • Examples of saturated fatty acids are: lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid and the like, or mixtures thereof.
  • Plant oils such as, for example: epoxidized linseed oil, epoxidized safflower oil, epoxidized soybean oil, epoxidized corn oil, epoxidized cottonseed oil, epoxidized rapeseed oil, epoxidized castor oil, epoxidized tung oil, epoxidized tall oil, octyl epoxytallate, epoxidized sunflower oil, epoxidized olive oil and the like, or mixtures thereof, are particularly preferred.
  • the epoxidized oils generally have a freezing temperature of less than 23°C, preferably less than 10°C.
  • Another class of liquid organic compounds containing internal epoxide groups which can be used advantageously according to the present invention consists of epoxidized diene oligomers, wherein the base polymer structure, of synthetic or natural origin, is derived from one or more conjugated diene monomers, optionally copolymerized with other monomers containing ethylenic unsaturation.
  • These oligomers generally have an average molecular weight (number-average) , which can be determined, for example, by gel permeation chromatography (GPC) , of between 500 and 10,000, preferably between 1,000 and 8,000.
  • the diene monomers can optionally be copolymerized with other monomers containing ethylenic unsaturation, such as, for example: alpha-olefins containing from 2 to 12 carbon atoms (for example ethylene, propylene or 1-butene) , monovinylarenes containing from 8 to 20 carbon atoms (for example styrene, 1-vinylnaphthalene or 3-methylstyrene) , vinyl esters wherein the ester group contains from 2 to 8 carbon atoms (for example vinyl acetate, vinyl propionate or vinyl butanoate) , alkyl acrylates and alkyl methacrylates wherein the alkyl contains from 1 to 8 carbon atoms (for example ethyl acrylate, methyl acrylate, methyl methacrylate, tert-butyl acrylate or n- butyl acrylate) , acrylonitrile, and the like, or mixtures thereof.
  • epoxidized diene oligomers preferred are those obtained by epoxidation of oligomers of: 1,3- butadiene; isoprene; 1, 3-butadiene and styrene; 1,3- butadiene and isoprene; isoprene and styrene; 1,3- butadiene and acrylonitrile; and the like.
  • Epoxidized oligomers of 1, 3-butadiene or of isoprene are particularly preferred.
  • Epoxidized diene oligomers which can be used in the present invention are commercially available, for example under the brand name Poly BD® from Elf Atochem.
  • the epoxidation reaction of a compound containing internal alkylene groups can be carried out according to known techniques.
  • the starting material can be subjected to direct oxidation using a suitable oxidizing agent such as a peracid (in particular perbenzoic acid, metachloroperbenzoic acid, peracetic acid, trifluoroperacetic acid, perpropionic acid, and the like) or an alkaline oxidizing agent (for example hydrogen peroxide mixed with aqueous sodium hydroxide solution) , or alternatively by reaction with oxygen gas in the presence of a catalyst (for example Ag) .
  • a suitable oxidizing agent such as a peracid (in particular perbenzoic acid, metachloroperbenzoic acid, peracetic acid, trifluoroperacetic acid, perpropionic acid, and the like) or an alkaline oxidizing agent (for example hydrogen peroxide mixed with aqueous sodium hydroxide solution) , or alternatively by reaction with oxygen gas in the presence of a catalyst
  • the elastomeric polymers containing carboxylic groups (also referred to for simplicity hereinbelow as “carboxylated elastomeric polymers”) which can be used in accordance with the present invention are homopolymers or copolymers with elastomeric properties, which have a glass transition temperature (Tg) of less than 23°C, preferably less than 0°C, and which contain at least 0.1 mol%, preferably from 1 to 30 mol% and even more preferably from 2 to 10 mol%, of carboxylic groups relative to the total number of moles of monomers present in the polymer.
  • Tg glass transition temperature
  • the base polymer structure is obtained by (co) polymerization of diene monomers containing from 4 to 12, preferably from 4 to 8, carbon atoms, selected, for example, from: 1, 3-butadiene, isoprene, 2 , 3-dimethyl-l, 3-butadiene, 3-butyl-l,3- octadiene, 2-pheny1-1, 3-butadiene and the like, or mixtures thereof.
  • 1, 3-Butadiene and isoprene are particularly preferred.
  • Monovinylarenes which can optionally be used as comonomers generally contain from 8 to 20, preferably from 8 to 12, carbon atoms and can be selected, for example, from: styrene; 1-vinylnaphthalene; 2-vinyl- naphthalene; various alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl derivatives of styrene, such as, for example: 3-methylstyrene, 4-propylstyrene, 4-cyclo- hexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-p-tolylstyrene, 4- (4-phenylbutyl) styrene and the like, or mixtures thereof.
  • Styrene is particularly preferred. These monovinylarenes can optionally be substituted with one or more functional groups, such as alkoxy groups, for example 4-methoxystyrene, amino groups, for example 4- dimethylaminostyrene, and the like.
  • Various polar comonomers can be introduced into the base polymer structure, in particular vinylpyridine, vinylquinoline, acrylic and alkylacrylic acid esters, nitriles and the like, or mixtures thereof, such as, for example: methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate and acrylonitrile.
  • base polymer structures which are particularly preferred are: natural rubber, polybutadiene, polyisoprene, styrene/butadiene copolymers, butadiene/isoprene copolymers, styrene/isoprene copolymers, butadiene/acrylonitrile copolymers and the like, or mixtures thereof.
  • the amount of diene comonomer relative to the other comonomers is such as to ensure that the final polymer has elastomeric properties. In this respect, it is not possible generally to establish the minimum amount of diene comonomer required to obtain the desired elastomeric properties. As an indication, an amount of diene comonomer of at least 50% by weight relative to the total weight of the comonomers can generally be considered sufficient.
  • the preparation of the base polymer can be carried out according to known techniques, generally by (co) polymerization of the corresponding monomers in emulsion, in suspension or in solution.
  • the base polymer thus obtained can be made to react with a carboxylating agent in the presence of a radical initiator, preferably an organic peroxide (for example dicumyl peroxide or benzoyl peroxide) .
  • a radical initiator preferably an organic peroxide (for example dicumyl peroxide or benzoyl peroxide) .
  • Carboxylating agents commonly used are, for example: maleic anhydride, itaconic anhydride, thioglycolic acid, beta-mercaptopropionic acid and the like.
  • carboxylic groups can also be carried out during the synthesis of the polymer by copolymerization between a conjugated diene, optionally mixed with monovinylarenes and/or polar comonomers, as reported above, and an olefinic monomer containing one or more carboxylic groups, or a derivative thereof.
  • Carboxylated olefinic monomers usually used are, for example: acrylic acid, methacrylic acid, sorbic acid, beta-acryloxypropanoic acid, ethacrylic acid, 2-ethyl-3- propylacrylic acid, vinylacrylic acid, itaconic acid, cinnamic acid, maleic acid, fumaric acid and the like, or mixtures thereof.
  • carboxylated elastomeric polymers the following are particularly preferred: 1 , 3-butadiene/ (meth) acrylic acid copolymers, 1, 3-butadiene/acrylonitrile/ (meth) acrylic acid copolymers, 1, 3-butadiene/styrene/ (meth) acrylic acid copolymers and the like, or mixtures thereof.
  • the corresponding carboxylic derivatives can be used, in particular anhydrides, esters, nitriles or amides.
  • the polymer obtained is then subjected to hydrolysis so as to convert, partially or totally, the functional groups thus introduced into free carboxylic groups.
  • Carboxylated elastomeric polymers which may also be used are elastomeric copolymers of one or more monoolefins with an olefinic comonomer containing one or more carboxylic groups or derivatives thereof.
  • the monoolefins can be selected from: ethylene and alpha- olefins generally containing from 3 to 12 carbon atoms, such as, for example: propylene, 1-butene, 1-pentene, 1- hexene, 1-octene and the like, or mixtures thereof.
  • copolymers between ethylene and an alpha-olefin, and optionally a diene are preferred: copolymers between ethylene and an alpha-olefin, and optionally a diene; homopolymers of isobutene or copolymers thereof with small amounts of a diene, which are optionally at least partially halogenated.
  • the optional diene contains, in general, 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, and the like.
  • ethylene/ propylene copolymers EPR
  • ethylene/propylene/diene copolymers EPDM
  • polyisobutene butyl rubbers
  • halobutyl rubbers in particular chlorobutyl or bromobutyl rubbers
  • carboxylated olefinic comonomers can be selected from those mentioned above for the diene polymers.
  • a diene comonomer When a diene comonomer is present, it can be used to introduce carboxylic groups by means of the carboxylation reaction as described above. Further information regarding structure and production processes of carboxylated elastomers are given, for example, in the article by H.P.
  • the epoxidized liquid compound is mixed with the carboxylated elastomeric polymer in proportions which vary as a function of the amount of functional groups present and as a function of the elastic properties which it is desired to obtain for the final product.
  • the amount of epoxidized liquid compound can range between 5 and 200 parts by weight, preferably between 10 and 120 parts by weight, per 100 parts by weight of elastomeric polymer.
  • an effective amount of a crosslinking accelerator is added to the crosslinkable compositions according to the present invention.
  • Said crosslinking accelerator comprises at least an oxide or an inorganic salt of a metal selected from Fe, Cu, Sn, Mo and Ni . When an inorganic salt is used, it is preferably selected from chlorides, bromides, sulfates, nitrates, either hydrated or anhydrous .
  • the crosslinking accelerator is selected from SnCl 2 .2H 2 0 CuS0 4 .5H 2 0 (NH 4 ) 2 Fe (SO 2 .6H 2 0, NiNO 3 .6H 2 0, Mo0 3.
  • the amount of oxide or inorganic salt to be added is generally from 0.1 to 2 parts by weight of metal, preferably from 0.4 to 1 parts by weight, relative to 100 parts by weight of carboxylated elastomeric polymer.
  • the accelerator can be used in admixture with a condensation catalyst, for example selected from: carboxylates of metals such as tin, zinc, zirconium, iron, lead, cobalt, barium, calcium, manganese and the like, for example: dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate, stannous acetate, stannous caprylate, lead naphthenate, zinc caprylate, zinc naphthenate, cobalt naphthenate, ferrous octanoate, iron 2-ethylhexanoate, and the like; arylsulphonic acids or derivatives thereof, for example: p-dodecylbenzenesulphonic acid, tetrapropylbenzenesulphonic acid, acetyl p- dodecylbenzenesulphonate, 1-naphthalene sulphonic acid, 2-naphthalene
  • the reinforcing filler can be selected from those commonly used for crosslinked products, and in particular for tyres, such as: carbon black, silica, alumina, aluminosilicates, calcium carbonate, kaolin and the like, or mixtures thereof.
  • crosslinkable compositions according to the present invention can comprise other commonly used additives selected on the basis of the specific application for which they are intended.
  • antioxidants for example, the following can be added to these compositions: antioxidants, protective agents, plasticizers, compatibilizing agents for the reinforcing filler, adhesives, anti-ozone agents, modifying resins, fibres (for example Kevlar ® pulp) and the like.
  • a lubricant can be added to the crosslinkable compositions according to the present invention, this lubricant being selected in general from mineral oils, vegetable oils, synthetic oils and the like, or mixtures thereof, for example: aromatic oil, naphthenic oil, phthalic oil, soybean oil and the like.
  • the amount of lubricant can range in general from 2 to 100 phr, preferably from 5 to 50 phr.
  • the crosslinkable compositions according to the present invention can be prepared by mixing the polymer base and the reinforcing filler optionally present and the other additives according to techniques known in the art.
  • the mixing can be carried out, for example, using an open-mill mixer, or an internal mixer of the type with tangential rotors (Banbury) or interlocking rotors (Intermix) , or in continuous mixers of the Ko-Kneader (Buss) or co-rotating or counter-rotating twin-screw type.
  • the temperature is kept below a predetermined value so as to avoid premature crosslinking of the composition.
  • the temperature is generally kept below 170°C, preferably below 150°C, even more preferably below 140°C.
  • the mixing time this can vary within a wide range, depending mainly on the specific composition of the mixture, on the presence of any fillers and on the type of mixer used. In general, a mixing time of more than 90 sec, preferably between 3 and 35 min, is sufficient to obtain a homogeneous composition.
  • multi-step mixing processes can also be employed, optionally using a combination of different mixers arranged in series.
  • the crosslinkable compositions according to the present invention can advantageously be prepared by mixing the epoxidized liquid compound, and optionally the reinforcing filler and the other additives, with the polymer base in the form of an aqueous emulsion or a solution in an organic solvent.
  • the filler can be used as such or in the form of a suspension or dispersion in an aqueous medium.
  • the polymer is subsequently separated from the solvent or from the water by suitable means.
  • the polymer in emulsion the polymer can be precipitated in the form of particles including the oily phase and any filler by adding a coagulant.
  • a coagulant which can be used in particular is an electrolytic solution, for example an aqueous sodium or potassium silicate solution.
  • the coagulation process can be promoted by using a volatile organic solvent which is then removed by evaporation during precipitation of the filled polymer. Further details regarding processes of this type for the preparation of elastomeric compositions are given, for example, in US patent 3,846,365.
  • the present invention will now be illustrated in further detail by means of a number of working examples, with reference to: the attached Figure 1, which is a view in cross section with partial cutaway of a tyre according to the present invention.
  • a tyre 1 conventionally comprises at least one carcass ply 2 whose opposite side edges are coupled to respective anchoring bead wires 3, each enclosed in a bead 4 defined along an inner circumferential edge of the tyre, with which the tyre engages on a rim 5 forming part of the wheel of a vehicle.
  • the coupling between the carcass ply 2 and the bead wires 3 is usually carried out by folding the opposite lateral edges of the carcass ply 2 around the bead wires 3, so as to form the so-called carcass folds.
  • the conventional bead wires 3 can be replaced with a pair of circumferentially unextensible annular inserts formed from elongated components arranged in concentric spirals (not represented in Fig. 1) (see, for example, European patent applications EP-A-0 928 680 and EP-A-0 928 702) .
  • the carcass ply 2 is not folded around the said annular inserts, the coupling being provided by a second carcass ply (not represented in Fig. 1) applied externally onto the first.
  • the carcass ply 2 Along the circumference of the carcass ply 2 are applied one or more belt strips 6, made using metal or textile cords enclosed in a rubber sheet. Outside the carcass ply 2, in respective opposite side portions of this ply, there is also applied a pair of side walls 7, each of which extends from the bead 4 to a so-called "shoulder" region 8 of the tyre, defined by the opposing ends of the belt strips 6. On the belt strips 6 is circumferentially applied a tread band 9 whose side edges end at the shoulders 8, joining it to the side walls 7.
  • the tread band 9 has an external rolling surface 9a, intended to come into contact with the ground, in which circumferential grooves 10 intercalated with transverse cuttings (not shown in the attached figure) can be provided which define a plurality of blocks 11 variously distributed on the said rolling surface 9a.
  • the process for producing the tyre according to the present invention can be carried out according to techniques and using apparatus known in the art (see, for example, patents EP-199 064, US-4 872 822 and US-4 768 937) . More particularly, this process comprises a step of manufacturing the green tyre, in which a series of semifinished elements, prepared beforehand and separately from each other and corresponding to the various parts of the tyre (carcass plies, belt strips, bead wires, fillings, side walls and tread band) are combined together using a suitable manufacturing machine.
  • the green tyre can be moulded by introducing a pressurized fluid into the space defined by the inner surface of the tyre, so as to press the outer surface of the green tyre against the walls of the moulding cavity.
  • a vulcanization chamber made of elastomeric material, filled with steam and/or another fluid under pressure, is inflated inside the tyre closed inside the moulding cavity. In this way, the green tyre is pushed against the inner walls of the moulding cavity, thus obtaining the desired moulding.
  • the moulding can be carried out without an inflatable vulcanization chamber, by providing inside the tyre a toroidal metal support shaped according to the configuration of the inner surface of the tyre to be obtained (see, for example, patent EP-242,840).
  • a toroidal metal support shaped according to the configuration of the inner surface of the tyre to be obtained (see, for example, patent EP-242,840).
  • the difference in coefficient of thermal expansion between the toroidal metal support and the crude elastomeric material is exploited to achieve an adequate moulding pressure.
  • the step of crosslinking of the crude elastomeric material present in the tyre is carried out.
  • the outer wall of the vulcanization mould is placed in contact with a heating fluid
  • the inner surface of the tyre is brought to the crosslinking temperature using the same pressurized fluid used to press the tyre against the walls of the moulding cavity, heated to a maximum temperature of between 100 and 250°C.
  • the time required to obtain a satisfactory degree of crosslinking throughout the mass of the elastomeric material can vary in general between 3 min and 90 min and depends mainly on the dimensions of the tyre.
  • compositions reported in Table 1 were prepared using an open cylinder mixer, with a mixing time of about 30 min, reaching a final temperature of about 130°C.
  • t90 value is reported, i.e. the time corresponding to a torque value of ML+0.9 (MH-ML) , wherein ML is the value of minimun torque, and MH is the value of maximum torque.
  • XNBR terpolymer acrylonitrile/butadiene/carboxylated monomer containing 28% by weight of acrylonitrile and 7.5% by weight of carboxylic groups (Nipol EP® 1072, Nippon Zeon) ;

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Polymers & Plastics (AREA)
  • Mechanical Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Thermal Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Heating, Cooling, Or Curing Plastics Or The Like In General (AREA)

Abstract

L'invention concerne un procédé de fabrication de pneumatiques, selon lequel la réticulation est effectuée sur une composition comprenant : (a) au moins un polymère élastomère contenant des groupes carboxyle, (b) au moins un composé organique liquide contenant des groupes époxyde situés à l'intérieur de la molécule et (c) au moins un oxyde ou un sel inorganique d'un métal choisi parmi Fe, Cu, Sn, Mo et Ni. Quand on la chauffe, la matière élastomère atteint un degré élevé de réticulation sans addition d'agents de réticulation conventionnels, avec des temps de réticulation maintenus dans les limites acceptables pour un usage industriel. Ces compositions conviennent particulièrement à la fabrication de bandes de roulement.
PCT/EP2002/001109 2001-02-07 2002-02-04 Procede de fabrication de pneumatiques, pneumatiques obtenus par ce procede et compositions elastomeres utilisees selon ce procede Ceased WO2002062594A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BR0206932-6A BR0206932A (pt) 2001-02-07 2002-02-04 Processo para a produção de pneus para rodas de veìculo, pneu para rodas de veìculo, composição elastomérica reticulável, e, produto elastomérico réticulado
JP2002562579A JP2004522620A (ja) 2001-02-07 2002-02-04 タイヤの製造方法、その方法により得られるタイヤ、およびそのタイヤで使用されるエラストマー組成物
US10/467,295 US20040102557A1 (en) 2001-02-07 2002-02-04 Process for producing tyres, tyres thus obtained and elastomeric compositions used therein

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP01102664.8 2001-02-07
EP01102664A EP1231079B1 (fr) 2001-02-07 2001-02-07 Procédé de préparation de pneumatiques, compositions élastomériques et pneumatiques
US26805601P 2001-02-13 2001-02-13
US60/268,056 2001-02-13

Publications (1)

Publication Number Publication Date
WO2002062594A1 true WO2002062594A1 (fr) 2002-08-15

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BR (1) BR0206932A (fr)
WO (1) WO2002062594A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10381547B2 (en) 2011-09-29 2019-08-13 Sumitomo Riko Company Limited Dielectric film, method for manufacturing the same, and transducer including the same

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2140949A1 (de) * 1971-08-16 1973-03-01 Phoenix Gummiwerke Ag Verfahren zum herstellen von elastischen formkoerpern, insb. kfz-reifen durch giessen
US3910866A (en) * 1973-09-17 1975-10-07 Roger E Morris Acrylate rubber vulcanizable compositions
IT1245551B (it) * 1991-05-17 1994-09-29 Firestone Int Dev Spa Procedimento per la vulcanizzazione senza zolfo di un elastomero e mescole autovulcanizzanti a base di elastomeri epossidati.

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2140949A1 (de) * 1971-08-16 1973-03-01 Phoenix Gummiwerke Ag Verfahren zum herstellen von elastischen formkoerpern, insb. kfz-reifen durch giessen
US3910866A (en) * 1973-09-17 1975-10-07 Roger E Morris Acrylate rubber vulcanizable compositions
IT1245551B (it) * 1991-05-17 1994-09-29 Firestone Int Dev Spa Procedimento per la vulcanizzazione senza zolfo di un elastomero e mescole autovulcanizzanti a base di elastomeri epossidati.

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10381547B2 (en) 2011-09-29 2019-08-13 Sumitomo Riko Company Limited Dielectric film, method for manufacturing the same, and transducer including the same

Also Published As

Publication number Publication date
BR0206932A (pt) 2004-02-25
JP2004522620A (ja) 2004-07-29

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