Metal cord, rubber-cord complex and pneumatic tire using the same
View Patent ↗Rubber-cord complex 9 having improved wet heat adhesive property between rubber and cord. The rubber-cord complex includes cord 10 comprising drawn plated wire 17 prepared by providing brass plated layer 16 E on surface of element wire 15 and drawing the resulting plated wire and rubber 12 vulcanized and bonded to cord 10 . The rubber-cord complex 9 has adhesion reaction layer 25 (formed by cross-linking sulfur and copper) between rubber 12 and brass plated layer 16 E. Adhesion reaction layer 25 has average thickness of 50-1,000 nm. Interface S between adhesion reaction layer 25 and the rubber has a fractal dimension of 1.001-1.300 in a wet heat deterioration state after being subjected to vulcanization to bond rubber 12 thereto and being held at a temperature of 50-100° C. and a humidity of 60-100% for one hour to 20 days.
1. A method of producing a rubber-cord complex obtained by vulcanizing a rubber to adhere it to a metal cord comprising at least one drawn plated wire having a brass plated layer, wherein the rubber-cord complex has an adhesion reaction layer formed by a cross-linking reaction of sulfur in the rubber and copper in the brass plated layer, between the rubber and the brass plated layer, and in a wet heat deterioration state after being held in an atmosphere having a temperature of 80° C. and a relative humidity of 95% for 20 days, said rubber-cord complex has the average thickness of the adhesion reaction layer being from 50 to 1,000 nm, and the interface between the adhesion reaction layer and the rubber having a fractal dimension of 1.001 to 1.300, said method comprising:
a plating step for forming a brass plated layer containing copper, zinc, and cobalt on the surface of a metal wire, said plating step comprising:
forming a copper plated layer on the surface of a metal element wire by an electroplating treatment in a copper plating bath, wherein a current density of said electroplating treatment for the copper plated layer is 15 to 25 A/dm 2 ,
forming a plated layer of an alloy of zinc and cobalt on said copper plated layer by an electroplating treatment in an alloy bath containing zinc and cobalt, wherein a current density of said electroplating treatment for the plated layer of the alloy of zinc and cobalt is 40 to 60 A/dm 2 , and
forming the brass plated layer by thermal diffusion of the copper plated layer and the plated layer of the alloy of zinc and cobalt, wherein the thermal diffusion is conducted by a low temperature diffusion at a temperature of 500 to 550° C.;
a drawing step for drawing the plated wire provided with the brass plated layer by said plating step so as to obtain said drawn plated wire; and
a vulcanizing step for vulcanizing the rubber to adhere it to the metal cord comprising said drawn plate wire.
2. A method of producing a rubber-cord complex obtained by vulcanizing a rubber to adhere it to a metal cord comprising at least one drawn plated wire having a brass plated layer, wherein the rubber-cord complex has an adhesion reaction layer formed by a cross-linking reaction of sulfur in the rubber and copper in the brass plated layer, between the rubber and the brass plated layer, and in a wet heat deterioration state after being held in an atmosphere having a temperature of 80° C. and a relative humidity of 95% for 20 days, said rubber-cord complex has the average thickness of the adhesion reaction layer being from 50 to 1,000 nm, and the interface between the adhesion reaction layer and the rubber having a fractal dimension of 1.001 to 1.300, said method comprising:
a plating step for forming a brass plated layer containing copper, zinc, and cobalt on the surface of a metal wire, said plating step comprising:
forming a copper plated layer on the surface of a metal element wire by an electroplating treatment in a copper plating bath, wherein a current density of said electroplating treatment for the copper plated layer is 15 to 25 A/dm 2 ,
forming a zinc plated layer on said copper plated layer by an electroplating treatment in a zinc plating bath, wherein a current density of said electroplating treatment for the zinc plated layer is 40 to 60 A/dm 2 ,
forming a cobalt plated layer on said zinc plated layer by an electroplating treatment in a cobalt bath, wherein a current density of said electroplating treatment for the cobalt plated layer is 30 to 40 A/dm 2 , and
forming the brass plated layer by thermal diffusion of the copper plated layer, the zinc plated layer, and the cobalt plated layer, wherein the thermal diffusion is conducted by a low temperature diffusion at a temperature of 500 to 550° C.;
a drawing step for drawing the plated wire provided with the brass plated layer by said plating step so as to obtain said drawn plated wire; and
a vulcanizing step for vulcanizing the rubber to adhere it to the metal cord comprising said drawn plate wire.