Three-layered metal cable for tire carcass reinforcement

Abstract

The present invention relates to a three-layered metal cable of construction L+M+N usable as a reinforcing element for a tire carcass reinforcement, comprising an inner layer C 1 having L wires of diameter d 1 with L being from 1 to 4, surrounded by an intermediate layer C 2 of M wires of diameter d 2 wound together in a helix at a pitch p 2 with M being from 3 to 12, said layer C 2 being surrounded by an outer layer C 3 of N wires of diameter d 3 wound together in a helix at a pitch p 3 with N being from 8 to 20, said cable being characterised in that a sheath formed of a cross-linkable or cross-linked rubber composition based on at least one diene elastomer covers at least said layer C 2. The invention furthermore relates to the articles or semi-finished products made of plastics material and/or rubber which are reinforced by such a multi-layer cable, in particular to tires used in industrial vehicles, more particularly heavy-vehicle tires and their carcass reinforcement plies.

1 . A three-layered metal cable, comprising 
 1) an inner layer C1, comprising from 1 to 4 wires L having a diameter d 1 ;    2) an intermediate layer C2, which surrounds layer C1, wherein layer C2 comprises from 3 to 12 wires M having a diameter d 2 , and wherein wires M are wound together in a helix at a pitch p 2 ;    3) an outer layer C3, which surrounds layer C2, wherein layer C3 comprises from 8 to 20 wires N having a diameter d 3 , and wherein wires N are wound together in a helix at a pitch p 3 ; and    4) a rubber sheath formed of a cross-linkable or cross-linked rubber composition comprising at least one diene elastomer, wherein the rubber sheath covers at least layer C2.    
   
   
       2 . A cable according to  claim 1 , wherein the at least one diene elastomer of the sheath is selected from the group consisting of polybutadienes, natural rubber, synthetic polyisoprenes, butadiene copolymers, isoprene copolymers, and mixtures of said elastomers.  
   
   
       3 . A cable according to  claim 2 , wherein the at least one diene elastomer is selected from the group consisting of natural rubber, synthetic polyisoprenes and mixtures of said elastomers.  
   
   
       4 . A cable according to  claim 3 , wherein the at least one diene elastomer is natural rubber.  
   
   
       5 . A cable according to  claim 1 ,  2 ,  3  or  4 , wherein the rubber composition further comprises carbon black as reinforcing filler.  
   
   
       6 . A cable according to  claim 1 ,  2 ,  3  or  4 , wherein the rubber composition has, in the cross-linked state, a secant tensile modulus that is less than 20 MPa.  
   
   
       7 . A cable according to  claim 6 , wherein the secant tensile modulus is less than 12 MPa.  
   
   
       8 . A cable according to  claim 1 ,  2 ,  3  or  4 , wherein the cable is incorporated into a carcass reinforcement ply of a tire that comprises a rubber matrix, and wherein the rubber matrix of the carcass reinforcement ply comprises substantially the same rubber composition used to form the rubber sheath of the cable.  
   
   
       9 . A cable according to  claim 1 ,  2 ,  3  or  4 , wherein layer C3 is a saturated layer.  
   
   
       10 . A cable according to  claim 1 ,  2 ,  3  or  4 , wherein the rubber sheath additionally covers layer C1.  
   
   
       11 . A cable according to  claim 1 ,  2 ,  3  or  4 , wherein the rubber sheath separates adjacent wires M in layer C2.  
   
   
       12 . A cable according to  claim 1 ,  2 ,  3  or  4 , wherein the rubber sheath covers the radially inner half-circumference of each wire N of layer C3, and wherein the rubber sheath separates the adjacent wires N of layer C3.  
   
   
       13 . A cable according to  claim 1 ,  2 ,  3  or  4 , wherein layer C2 comprises 6 or 7 wires M.  
   
   
       14 . A cable according to  claim 1 ,  2 ,  3  or  4 , wherein the following relationships are satisfied: 
 1) 0.10 mm<d 1 <0.28 mm;    2) 0.10 mm<d 2 <0.25 mm;    3) 0.10 mm<d 3 <0.25 mm;    4) M=6 or M=7;    5) 5π(d 1 +d 2 )<p 2 ≦p 3 <5π(d 1 +2d 2 +d 3 );    6) the wires of layers C2 and C3 are wound in the same direction of twist.    
   
   
       15 . A cable according to  claim 14 , wherein the following relationships are satisfied: 
 1) if M is 6, then the ratio (d 1 /d 2 ) is from 1.10 to 1.40; and    2) if M is 7, then the ratio (d 1 /d 2 ) is from 1.40 to 1.70.    
   
   
       16 . A cable according to  claim 15 , wherein p 2 =p 3 .  
   
   
       17 . A cable according to  claim 16 , wherein the outer layer C3 has a substantially circular cross-section.  
   
   
       18 . A cable according to  claim 1 ,  2 ,  3  or  4 , wherein layer C1 comprises 1 wire L.  
   
   
       19 . A cable according to  claim 18 , wherein the wire composition of the cable is selected from the group consisting of 
 1) layer C2 comprises 6 wires M and layer C3 comprises 10 wires N;    2) layer C2 comprises 6 wires M and layer C3 comprises 11 wires N;    3) layer C2 comprises 6 wires M and layer C3 comprises 12 wires N;    4) layer C2 comprises 7 wires M and layer C3 comprises 11 wires N;    5) layer C2 comprises 7 wires M and layer C3 comprises 12 wires N; and    6) layer C2 comprises 7 wires M and layer C3 comprises 13 wires N.    
   
   
       20 . A cable according to  claim 19 , wherein layer C2 comprises 6 wires M and layer C3 comprises 12 wires N.  
   
   
       21 . A cable according to  claim 14 , wherein the following relationships are satisfied: 
 1) 0.18 mm<d 1 <0.24 mm;    2) 0.16 mm<d 2 ≦d 3 <0.19 mm; and    3) 5 mm<p 2 ≦p 3 <12 mm.    
   
   
       22 . A cable according to  claim 14 , wherein the following relationships are satisfied: 
 1) 0.18 mm<d 1 <0.24 mm;    2) 0.16 mm<d 2 <d 3 <0.19 mm; and    3) 20 mm<p 2 ≦p 3 <30 mm.    
   
   
       23 . A cable according to  claim 1 ,  2 ,  3  or  4 , wherein the rubber sheath has an average thickness of from 0.010 mm to 0.040 mm.  
   
   
       24 . A cable according to  claim 1 ,  2 ,  3  or  4 , wherein wires L, M, and N comprise carbon steel.  
   
   
       25 . A cable according to  claim 24 , wherein the carbon content of the carbon steel is from 0.4% to 1.0%.  
   
   
       26 . A reinforcing element for articles of plastics material and/or of rubber, comprising a cable according to  claim 1 ,  2 ,  3  or  4 .  
   
   
       27 . A reinforcing element for semi-finished products of plastics material and/or of rubber, comprising a cable according to  claim 1 ,  2 ,  3  or  4 .  
   
   
       28 . A reinforcing element for a carcass reinforcement for an industrial-vehicle tire, comprising a cable according to  claim 1 ,  2 ,  3  or  4 .  
   
   
       29 . A semi-finished product of plastics material and/or rubber, comprising a reinforcing element, wherein the reinforcing element comprises a cable according to  claim 1 ,  2 ,  3  or  4 .  
   
   
       30 . A composite fabric usable as carcass reinforcement ply for a heavy-vehicle tire, comprising a rubber matrix, wherein the rubber matrix is reinforced by a cable according to  claim 1 ,  2 ,  3  or  4 .  
   
   
       31 . A composite fabric according to  claim 30 , wherein the rubber matrix has, in the cross-linked state, a secant tensile modulus that is less than 20 MPa.  
   
   
       32 . A composite fabric according to  claim 31 , wherein the secant tensile modulus is less than 12 MPa.  
   
   
       33 . A tire reinforced by a cable according to  claim 1 ,  2 ,  3  or  4 .  
   
   
       34 . A tire comprising a composite fabric according to  claim 32 .  
   
   
       35 . A tire for an industrial vehicle, wherein said tire comprises a carcass reinforcement which is anchored in two beads and which is radially surmounted by a crown reinforcement which in turn is surmounted by a tread which is joined to said beads by two sidewalls, wherein the carcass reinforcement comprises cables according to  claim 1 ,  2 ,  3  or  4 .  
   
   
       36 . A tire for an industrial vehicle, wherein said tire comprises a carcass reinforcement which is anchored in two beads and which is radially surmounted by a crown reinforcement which in turn is surmounted by a tread which is joined to said beads by two sidewalls, wherein the carcass reinforcement comprises a composite fabric according to  claim 30 .  
   
   
       37 . A tire according to  claim 35 , wherein the tire is for a heavy vehicle.  
   
   
       38 . A tire according to  claim 36 , wherein the tire is for a heavy vehicle.