Sealing material, tire for a vehicle wheel including the sealing material, and process for producing the tyre

Abstract

A sealing material includes the following characteristics: a value of a dynamic elastic modulus, measured at a temperature of 80° C., at a frequency of 1 Hz, and with a deformation of 5%, that is at least 60% lower than a value of the dynamic elastic modulus measured at the temperature of 80° C., at the frequency of 1 Hz, and with a deformation of 1%; and the value of the dynamic elastic modulus, measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 5%, that is greater than or equal to 0.05 kPa. A tyre for a vehicle wheel includes a carcass structure comprising at least one carcass ply and at least one layer of sealing material disposed in a radially inner position with respect to the at least one carcass ply. A process for producing the tyre is also disclosed.

1 - 29 . (canceled) 
   
   
       30 . A tyre for a vehicle wheel, comprising:
 a carcass structure comprising at least one carcass ply;   a belt structure disposed in a circumferentially outer position with respect to the carcass structure;   a tread circumferentially superimposed on the belt structure;   a pair of sidewalls disposed laterally on opposite sides with respect to the carcass structure; and   at least one layer of sealing material;   wherein the at least one carcass ply is shaped in a substantially toroidal configuration,   wherein opposite lateral edges of the at least one carcass ply are associated with respective bead wires,   wherein each bead wire is enclosed in a respective bead,   wherein the belt structure comprises at least one belt strip,   wherein the at least one layer of sealing material is disposed in a radially inner position with respect to the at least one carcass ply, and   wherein the sealing material comprises the following characteristics:
 a value of a dynamic elastic modulus, measured at a temperature of 80° C., at a frequency of 1 Hz, and with a deformation of 5%, that is at least 60% lower than the value of the dynamic elastic modulus measured at the temperature of 80° C., at the frequency of 1 Hz, and with a deformation of 1%; and 
 the value of the dynamic elastic modulus, measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 5%, that is greater than or equal to 0.05 kPa. 
   
   
   
       31 . The tyre of  claim 30 , wherein the sealing material comprises the following characteristics:
 the value of the dynamic elastic modulus, measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 5%, that is at least 60% lower than the value of the dynamic elastic modulus measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 1%; and   the value of the dynamic elastic modulus, measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 5%, that is greater than or equal to 0.1 kPa and less than or equal to 0.4 kPa.   
   
   
       32 . The tyre of  claim 30 , wherein the at least one layer of sealing material is disposed between:
 the at least one carcass ply; and   a first layer of elastomeric material disposed in a radially inner position with respect to the at least one carcass ply.   
   
   
       33 . The tyre of  claim 32 , wherein a second layer of elastomeric material is disposed between the at least one layer of sealing material and the at least one carcass ply. 
   
   
       34 . The tyre of  claim 30 , wherein the at least one layer of sealing material extends over a surface substantially corresponding to a surface of development of the tread. 
   
   
       35 . The tyre of  claim 30 , wherein a strip of elastomeric material is placed along each axially outer edge of the at least one layer of sealing material. 
   
   
       36 . The tyre of  claim 30 , wherein the at least one layer of sealing material comprises a thickness greater than or equal to 1.5 mm and less than or equal to 4.5 mm. 
   
   
       37 . A process for producing a tyre for a vehicle wheel, comprising:
 making at least one coating layer of cross-linkable elastomeric material on an outer surface of a toroidal support whose shape is essentially complementary to an inner surface of the tyre;   making at least one layer consisting of a composition comprising at least one thermally degradable polymer in a circumferentially outer position with respect to the at least one coating layer;   disposing a carcass structure comprising at least one carcass ply in a circumferentially outer position with respect to the at least one layer consisting of a composition comprising at least one thermally degradable polymer;   disposing a belt structure in a circumferentially outer position with respect to the carcass structure;   disposing a tread in a circumferentially outer position with respect to the belt structure;   disposing at least one pair of sidewalls on the carcass structure in laterally opposite positions;   subjecting the at least one coating layer, the at least one layer consisting of a composition comprising at least one thermally degradable polymer, the carcass structure, the belt structure, the tread, and the at least one pair of sidewalls to moulding in a cavity formed in a vulcanization mould; and   subjecting the at least one coating layer, the at least one layer consisting of a composition comprising at least one thermally degradable polymer, the carcass structure, the belt structure, the tread, and the at least one pair of sidewalls to cross-linking by heating to a predetermined temperature and for a predetermined period of time;   wherein, at an end of the cross-linking, the composition comprising at least one thermally degradable polymer comprises the following characteristics:
 a value of a dynamic elastic modulus, measured at a temperature of 80° C., at a frequency of 1 Hz, and with a deformation of 5%, that is at least 60% lower than the value of the dynamic elastic modulus measured at the temperature of 80° C., at the frequency of 1 Hz, and with a deformation of 1%; and 
 the value of the dynamic elastic modulus, measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 5%, that is greater than or equal to 0.05 kPa. 
   
   
   
       38 . The process of  claim 37 , wherein, at the end of the cross-linking, the composition comprising at least one thermally degradable polymer comprises the following characteristics:
 the value of the dynamic elastic modulus, measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 5%, that is at least 60% lower than the value of the dynamic elastic modulus measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 1%; and   the value of the dynamic elastic modulus, measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 5%, that is greater than or equal to 0.1 kPa and less than or equal to 0.4 kPa.   
   
   
       39 . The process of  claim 37 , wherein the cross-linking is carried out by heating the at least one coating layer, the at least one layer consisting of a composition comprising at least one thermally degradable polymer, the carcass structure, the belt structure, the tread, and the at least one pair of sidewalls to a temperature greater than or equal to 100° C. and less than or equal to 250° C. 
   
   
       40 . The process of  claim 37 , wherein the at least one layer consisting of a composition comprising at least one thermally degradable polymer is obtained by winding at least one ribbon band consisting of the composition comprising at least one thermally degradable polymer in close coils along a cross-sectional profile of the toroidal support. 
   
   
       41 . A sealing material comprising the following characteristics:
 a value of a dynamic elastic modulus, measured at a temperature of 80° C., at a frequency of 1 Hz, and with a deformation of 5%, that is at least 60% lower than a value of the dynamic elastic modulus measured at the temperature of 80° C., at the frequency of 1 Hz, and with a deformation of 1%; and   the value of the dynamic elastic modulus, measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 5%, that is greater than or equal to 0.05 kPa.   
   
   
       42 . The material of  claim 41 , comprising the following characteristics:
 the value of the dynamic elastic modulus, measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 5%, that is at least 60% lower than the value of the dynamic elastic modulus measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 1%; and   the value of the dynamic elastic modulus, measured at the temperature of 80° C., at the frequency of 1 Hz, and with the deformation of 5%, that is greater than or equal to 0.1 kPa and less than or equal to 0.4 kPa.