Process for producing tyres, tyres thus obtained and elastomeric compositions used therein

Abstract

A crosslinkable elastomeric composition includes at least one elastomeric polymer including carboxylic groups, and at least one epoxidized elastomeric polymer including greater than or equal to 0.1 mol % and less than or equal to 20 mol % of epoxide groups relative to a total number of moles of monomers present in the at least one epoxidized elastomeric polymer. The composition is crosslinkable in a substantial absence of additional crosslinking agents. A tyre for vehicles includes a carcass structure, a belt structure extended coaxially around the carcass structure, and a tread band extended coaxially around the belt structure. The tread band comprises an external rolling surface intended to come into contact with the ground. In one embodiment of the present invention, the tread band includes at least one crosslinked elastomeric material. A process for producing the tyre is also disclosed.

1 . Process for producing tyres for vehicle wheels, said process comprising the following stages: 
 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) an elastomeric polymer containing carboxylic, groups, and (b) an epoxidized elastomeric polymer containing from 0.1 mol % to 20 mol % of epoxide groups relative to the total number of moles of monomers present in the polymer, in which said crosslinking stage is carried out in the substantial absence of additional crosslinking agents.    
     
     
         2 . Process according to  claim 1 , in which the crosslinking stage 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.  
     
     
         3 . Process according to  claim 2 , in which the crosslinking stage is carried out by heating the crosslinkable elastomeric material to a temperature of from 130° C. to 230° C. for a time of from 5 to 90 minutes.  
     
     
         4 . Process according to any one of the preceding claims, in which the elastomeric material also comprises a reinforcing filler.  
     
     
         5 . Process according to  claim 4 , in which the reinforcing filler is present in an amount of between 10 and 120 phr.  
     
     
         6 . Process according to  claim 5 , in which the reinforcing filler is present in an amount of between 30 and 100 phr.  
     
     
         7 . Process according to any one of the preceding claims, in which said crosslinkable elastomeric material comprises a lubricant.  
     
     
         8 . Process according to  claim 7 , in which said lubricant is an epoxidized lubricant containing epoxide groups located internally on the molecule.  
     
     
         9 . Process according to  claim 8 , in which said epoxidized lubricant has an epoxide-equivalent weight of between 40 and 2,000.  
     
     
         10 . Process according to any one of  claims 7  to  9 , in which said lubricant is an epoxidized oil.  
     
     
         11 . Process according to any one of  claims 7  to  9 , in which the epoxidized lubricant is an epoxidized diene oligomer.  
     
     
         12 . Process according to any one of the preceding claims, in which the elastomeric polymer containing carboxylic groups is a homopolymer or copolymer containing at least 0.1 mol % of carboxylic groups relative to the total number of moles of monomers present in the polymer.  
     
     
         13 . Process according to  claim 12 , in which the carboxylated elastomeric polymer contains from 1 mol % to 30 mol % of carboxylic groups relative to the total number of moles of monomers present in the polymer.  
     
     
         14 . Process according to  claim 13 , in which the carboxylated elastomeric polymer contains from 2 mol % to 10 mol % of carboxylic groups relative to the total number of moles of monomers present in the polymer.  
     
     
         15 . Process according to any one of the preceding claims, in which the carboxylated elastomeric polymer has an average molecular weight of between 2,000 and 1,000,000.  
     
     
         16 . Process according to  claim 15 , in which the carboxylated elastomeric polymer has an average molecular weight of between 50,000 and 500,000.  
     
     
         17 . Process according to any one of the preceding claims, in which the carboxylated elastomeric polymer is obtained by (co)polymerization of one or more conjugated diene monomers, optionally mixed with monovinylarenes and/or polar comonomers, followed by carboxylation.  
     
     
         18 . Process according to any one of  claims 1  to  16 , in which the carboxylated elastomeric polymer is obtained by copolymerization of a conjugated diene, optionally mixed with monovinylarenes and/or polar comonomers, and an olefinic monomer containing one or more carboxylic groups or a derivative thereof.  
     
     
         19 . Process according to any one of  claims 1  to  16 , in which the carboxylated elastomeric polymer is obtained by copolymerization of one or more monoolefins with an olefinic comonomer containing one or more carboxylic groups, or derivatives thereof.  
     
     
         20 . Process according to any one of the preceding claims, in which the epoxidized elastomeric polymer contains from 0.5 mol % to 15 mol % of epoxide groups relative to the total number of moles of monomers present in the polymer.  
     
     
         21 . Process according to  claim 20 , in which the epoxidized elastomeric polymer contains from 1 mol % to 10 mol % of epoxide groups relative to the total number of moles of monomers present in the polymer.  
     
     
         22 . Process according to any one of the preceding claims, in which the epoxidized elastomeric polymer containing epoxide groups has a glass transition temperature (Tg) of less than 23° C.  
     
     
         23 . Process according to any one of the preceding claims, in which the epoxidized elastomeric polymer has an average molecular weight of between 2,000 and 1,000,000.  
     
     
         24 . Process according to  claim 23 , in which the epoxidized elastomeric polymer has an average molecular weight of between 50,000 and 500,000.  
     
     
         25 . Process according to any one of the preceding claims, in which the epoxidized elastomeric polymer is an epoxidized diene homopolymer or copolymer derived from one or more conjugated diene monomers, optionally copolymerized with monovinylarenes and/or polar comonomers.  
     
     
         26 . Process according to  claim 25 , in which the epoxidized elastomeric polymer is epoxidized natural rubber.  
     
     
         27 . Process according to any one of  claims 1  to  24 , in which the epoxidized elastomeric polymer is obtained by copolymerization of a conjugated diene, optionally mixed with monovinylarenes and/or polar comonomers, and an olefinic monomer containing one or more epoxide groups.  
     
     
         28 . Process according to any one of  claims 1  to  24 , in which the epoxidized elastomeric polymer is a copolymer of one or more monoolefins with an olefinic comonomer containing one or more epoxide groups.  
     
     
         29 . Tyre for vehicles wheels, comprising one or more components made of crosslinked elastomeric material, characterized in that at least one of said components comprises, as crosslinked elastomeric material, an elastomeric polymer containing carboxylic groups and an epoxidized elastomeric polymer containing from 0.1 mol % to 20 mol % of epoxide groups relative to the total number of moles of monomers present in the polymer, said polymers being crosslinked in the substantial absence of additional crosslinking agents.  
     
     
         30 . Tyre according to  claim 29 , in which said crosslinked elastomeric material also comprises a reinforcing filler.  
     
     
         31 . Tyre according to  claim 30 , in which the reinforcing filler is present in an amount of between 10 and 120 phr.  
     
     
         32 . Tyre according to  claim 31 , in which the reinforcing filler is present in an amount of between 30 and 100 phr.  
     
     
         33 . Tyre according to any one of  claims 29  to  32 , in which said crosslinked elastomeric material also comprises a lubricant.  
     
     
         34 . Tyre according to  claim 33 , in which said lubricant is defined according to any one of  claims 7  to  11 .  
     
     
         35 . Tyre according to any one of  claims 29  to  34 , in which the elastomeric polymer containing carboxylic groups is defined according to any one of  claims 12  to  19 .  
     
     
         36 . Tyre according to any one of  claims 29  to  35 , in which the epoxidized elastomeric polymer is defined according to any one of  claims 20  to  28 .  
     
     
         37 . 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 which is intended to come into contact with the ground, characterized in that said tread band comprises an elastomeric polymer containing carboxylic groups and an epoxidized elastomeric polymer containing from 0.1 mol % to 20 mol % of epoxide groups relative to the total number of moles of monomers present in the polymer, said polymers being crosslinked in the substantial absence of additional crosslinking agents.  
     
     
         38 . Tyre according to  claim 37 , in which the tread band also comprises a reinforcing filler.  
     
     
         39 . Tyre according to  claim 38 , in which the reinforcing filler is present in an amount of between 10 and 120 phr.  
     
     
         40 . Tyre according to  claim 39 , in which the reinforcing filler is present in an amount of between 30 and 100 phr.  
     
     
         41 . Tyre according to any one of  claims 37  to  40 , in which said crosslinked elastomeric material also comprises a lubricant.  
     
     
         42 . Tyre according to  claim 41 , in which said lubricant is defined according to any one of  claims 7  to  11 .  
     
     
         43 . Tyre according to any one of  claims 37  to  42 , in which the elastomeric polymer containing carboxylic groups is defined according to any one of  claims 12  to  19 .  
     
     
         44 . Tyre according to any one of  claims 37  to  43 , in which the epoxidized elastomeric polymer is defined according to any one of  claims 20  to  28 .  
     
     
         45 . Crosslinkable elastomeric composition comprising: (a) an elastomeric polymer containing carboxylic groups; and (b) an epoxidized elastomeric polymer containing from 0.1 mol % to 20 mol % of epoxide groups relative to the total number of moles of monomers present in the polymer; said composition being crosslinkable in the substantial absence of additional crosslinking agents.  
     
     
         46 . Crosslinkable elastomeric composition according to  claim 45 , also comprising a reinforcing filler.  
     
     
         47 . Composition according to  claim 46 , in which the reinforcing filler is present in an amount of between 10 and 120 phr.  
     
     
         48 . Composition according to  claim 47 , in which the reinforcing filler is present in an amount of between 30 and 100 phr.  
     
     
         49 . Composition according to any one of  claims 45  to  48 , also comprising a lubricant.  
     
     
         50 . Composition according to  claim 49 , in which said lubricant is an epoxidized lubricant containing epoxide groups located internally on the molecule.  
     
     
         51 . Composition according to  claim 50 , in which the epoxidized lubricant has an epoxide-equivalent weight of between 40 and 2,000.  
     
     
         52 . Composition according to  claim 51 , in which the epoxidized lubricant has an epoxide-equivalent weight of between 50 and 1,500.  
     
     
         53 . Composition according to  claim 52 , in which the epoxidized lubricant has an epoxide-equivalent weight of between 100 and 1,000.  
     
     
         54 . Composition according to any one of  claims 49  to  53 , in which the epoxidized lubricant is an epoxidized oil.  
     
     
         55 . Composition according to  claim 54 , in which the epoxidized oil has a freezing temperature of less than 23° C.  
     
     
         56 . Composition according to any one of  claims 49  to  53 , in which the epoxidized lubricant is an epoxidized diene oligomer.  
     
     
         57 . Composition according to  claim 56 , in which the epoxidized diene oligomer has an average molecular weight of between 500 and 10,000.  
     
     
         58 . Composition according to  claim 57 , in which the epoxidized diene oligomer has an average molecular weight of between 1,000 and 8,000.  
     
     
         59 . Composition according to any one of  claims 56  to  58 , in which the epoxidized diene oligomer is an epoxidized oligomer of 1,3-butadiene or isoprene, or blends thereof.  
     
     
         60 . Composition according to any one of  claims 45  to  59 , in which the elastomeric polymer containing carboxylic groups is a homopolymer or copolymer containing at least 0.1 mol % of carboxylic groups relative to the total number of moles of monomers present in the polymer.  
     
     
         61 . Composition according to  claim 60 , in which the carboxylated elastomeric polymer contains from 1 mol % to 30 mol % of carboxylic groups relative to the total number of moles of monomers present in the polymer.  
     
     
         62 . Composition according to any one of  claims 45  to  61 , in which the carboxylated elastomeric polymer has an average molecular weight of between 2,000 and 1,000,000.  
     
     
         63 . Composition according to  claim 62 , in which the carboxylated elastomeric polymer has an average molecular weight of between 50,000 and 500,000.  
     
     
         64 . Composition according to any one of  claims 45  to  63 , in which the carboxylated elastomeric polymer is obtained by (co)polymerization of one or more conjugated diene monomers, optionally mixed with monovinylarenes and/or polar comonomers, followed by carboxylation.  
     
     
         65 . Composition according to any one of  claims 45  to  63 , in which the carboxylated elastomeric polymer is obtained by copolymerization of a conjugated diene, optionally mixed with monovinylarenes and/or polar comonomers, and an olefinic polymer containing one or more carboxylic groups, or a derivative thereof.  
     
     
         66 . Composition according to any one of  claims 45  to  63 , in which the carboxylated elastomeric polymer is obtained by copolymerization of one or more monoolefins with an olefinic comonomer containing one or more carboxylic groups, or derivatives thereof.  
     
     
         67 . Composition according to any one of  claims 45  to  66 , in which the epoxidized elastomeric polymer contains from 0.5 mol % to 15 mol % of epoxide groups relative to the total number of moles of monomers present in the polymer.  
     
     
         68 . Composition according to  claim 67 , in which the epoxidized elastomeric polymer contains from 1 mol % to 10 mol % of epoxide groups relative to the total number of moles of monomers present in the polymer.  
     
     
         69 . Composition according to any one of  claims 45  to  68 , in which the epoxidized elastomeric polymer containing epoxide groups has a glass transition temperature (Tg) of less than 23° C.  
     
     
         70 . Composition according to any one of  claims 45  to  69 , in which the epoxidized elastomeric polymer has an average molecular weight of between 2,000 and 1,000,000.  
     
     
         71 . Composition according to  claim 70 , in which the epoxidized elastomeric polymer has an average molecular weight of between 50,000 and 500,000.  
     
     
         72 . Composition according to any one of  claims 45  to  71 , in which the epoxidized elastomeric polymer is an epoxidized diene homopolymer or copolymer derived from one or more conjugated diene monomers, optionally copolymerized with monovinylarenes and/or polar comonomers.  
     
     
         73 . Composition according to  claim 72 , in which the epoxidized elastomeric polymer is epoxidized natural rubber.  
     
     
         74 . Composition according to any one of  claims 45  to  71 , in which the epoxidized elastomeric polymer is a copolymer of one or more monoolefins with an olefinic comonomer containing one or more epoxide groups.  
     
     
         75 . Composition according to any one of  claims 45  to  71 , in which the epoxidized elastomeric polymer is obtained by copolymerization of a conjugated diene, optionally blended with monovinylarenes and/or polar comonomers, and an olefinic monomer containing one or more epoxide groups.  
     
     
         76 . Crosslinked elastomeric manufactured product obtained by crosslinking a composition according to any one of  claims 45  to  75 .