Hybrid dipped cord exhibiting excellent fatigue resistance and radial pneumatic tire having same applied thereto

Abstract

The present invention relates to a tire cord and a radial pneumatic tire, and is characterized in that when one raw nylon 6,6 or nylon 6 yarn and one aramid yarn are pre-twisted respectively and are then cabled to generate a raw cord, and when the raw cord is untwisted, the aramid yarn is input 5 to 100 mm/m longer than the nylon 6,6 or nylon 6 yarn. The hybrid dip cord according to the present invention has an excellent fatigue resistance of 80% or more, the initial deformation in the tensile test causes low modulus to be generated by nylon and causes high modulus to be expressed from the section where aramid begins to receive the force. As such, deformation is easy during the work of inflating the green tire inside the mold with the bladder, which makes the manufacturing of tires easy. Another object of the present invention relates to a method for producing a hybrid dip cord using nylon 6,6 yarn and aramid yarn, in which nylon 6,6 yarn and aramid yarn are pre-twisted by using one selected from the group consisting of a method of controlling the tension applied to the live cord, a method of adjusting the heat treatment temperature, and a method of controlling the heat treatment time, and they are cabled to make a raw cord, then the raw cord is dipped in an adhesive and is then heat-treated to thereby produce a dip cord in which nylon 6,6 has been further shrunk. Another object of the present invention is to provide a hybrid dip cord for a carcass ply or cap ply layer of a pneumatic radial tire having a certain degree of fatigue resistance, which is produced by dipping the raw cord using the nylon 6,6 and the aramid yarn in a dipping solution and then heat-treating the raw cord so that the nylon 6,6 may further shrink. In the present invention, twist numbers of aramid yarn and nylon yarn are kept the same during twisting, to thereby allowing a heat treatment process after producing a raw cord, by which the nylon yarn shrinks, and the aramid yarn is set to be longer than the nylon yarn per unit length when the dip cord is untwisted, thereby increasing the fatigue resistance. According to the present invention, it is possible to overcome the disadvantage that it is difficult to deform in a mold with a high modulus when using the aramid alone, and it is possible to improve low fatigue resistance and adhesion which are problematic when using aramid alone, and it is possible to produce high performance tires by improving low modulus and heat resistance that are problematic when using nylon 6,6 alone. Further, a method of manufacturing a hybrid dip cord according to the present invention includes: a step of preparing one nylon 6,6 yarn or nylon 6 yarn and one aramid yarn; a step of producing a primarily twisted yarn by applying a twist of 200 to 500 TPM by inputting one nylon 6,6 or nylon 6 yarn longer than the aramid yarn; a set of cabling the primarily twisted yarn as two to apply a twist of 200 to 500 TPM to thereby produce a raw cord; and a step of dipping the raw cord in an adhesive liquid and heat-treat the raw cord, in which the nylon 6,6 or nylon 6 is heat-shrunk so that the length of the nylon 6,6 or the nylon 6 becomes equal to the length of the aramid yarn.

1 .- 32 . (canceled) 
     
     
         33 . A hybrid dip cord for a radial pneumatic tire, characterized in that
 one nylon 6,6 yarn or nylon 6 yarn and one aramid yarn were pre-twisted respectively and cabled to thereby generate a raw cord, and   the raw cord is immersed in a dipping solution and then heat-treated to heat-shrink the nylon 6,6 yarn or the nylon 6 yarn so that the length of the nylon 6,6 yarn or the nylon 6 yarn is shorter than that of the aramid yarn.   
     
     
         34 . The hybrid dip cord of  claim 33 , wherein the shrinking of the nylon 6,6 or nylon 6 yarns in the heat treatment step uses one selected from the group consisting of a method of controlling the tension applied to the raw cord, a method of adjusting the heat treatment temperature, and a method of controlling the heat treatment time. 
     
     
         35 . The hybrid dip cord of  claim 33 , wherein when the raw cord is untwisted, the aramid yarn is 5 to 100 mm/m longer than the nylon 6,6 yarn or nylon yarn 6. 
     
     
         36 . The hybrid dip cord of  claim 33 , wherein when the raw cord is untwisted, the aramid yarn is 10 to 30 mm/m longer than the nylon 6,6 yarn or nylon yarn 6. 
     
     
         37 . The hybrid dip cord of  claim 33 , wherein a fatigue resistance of the hybrid dip cord is 80% or more. 
     
     
         38 . A method for manufacturing a hybrid dip cord for a radial pneumatic tire, the method comprising:
 a step of producing a primarily twisted yarn by applying 200 to 500 TPM twist respectively to one nylon 6,6 yarn or nylon 6 yarn and one aramid yarn;   a step of producing a raw cord by applying 200 to 500 TPM twist by combining the primarily twisted yarn as two yarns; and   a step of immersing the raw cord in a dipping solution and then heat-treating the raw cord to heat-shrink the nylon 6,6 yarn or the nylon 6 yarn so that the length of the nylon 6,6 yarn or the nylon 6 yarn is shorter than that of the aramid yarn.   
     
     
         39 . The method of  claim 38 , wherein the shrinking of the nylon 6,6 or nylon 6 yarns in the heat treatment step uses one selected from the group consisting of a method of controlling the tension applied to the raw cord, a method of adjusting the heat treatment temperature, and a method of controlling the heat treatment time. 
     
     
         40 . The method of  claim 39 , wherein the tension was controlled through the speed of the feed roller and the winding roller, the heat treatment temperature was 130 to 240° C., and the heat treatment time was 50 to 90 seconds. 
     
     
         41 . The method of  claim 38 , wherein when the raw cord is untwisted, the aramid yarn is 5 to 100 mm/m longer than the nylon 6,6 yarn or nylon yarn 6. 
     
     
         42 . The method of  claim 38 , wherein when the raw cord is untwisted, the aramid yarn is 10 to 30 mm/m longer than the nylon 6,6 yarn or nylon yarn 6. 
     
     
         43 . The method of  claim 38 , wherein the fineness of nylon 6,6 or nylon 6 yarn and aramid yarn is 500 to 3000 denier, respectively. 
     
     
         44 . A radial pneumatic tire comprising a pair of parallel bead cores, one or more layers of radial carcass layers wound around the bead cores, a belt layer piled on an outer peripheral side of each of the carcass layers, and a belt-reinforcing layer in a circumferential direction, formed on the outer peripheral side of the belt layer,
 wherein the carcass layer comprises a hybrid dip cord according to  claim 42 , wherein the carcass layer is used as one or two layers.   
     
     
         45 . A radial pneumatic tire comprising a pair of parallel bead cores, one or more layers of radial carcass layers wound around the bead cores, a belt layer piled on an outer peripheral side of each of the carcass layers, and a belt-reinforcing layer in a circumferential direction, formed on the outer peripheral side of the belt layer,
 wherein a cap ply which is, the belt-reinforcing layer, comprises a hybrid dip cord according to  claim 42 , wherein the cap ply is used as one or two layers.