Effect Of Coating And Rubber Formulation On Adhesion Property Between Bead Wire And Rubber

The paper is order to improve adhesion property between bead wire and rubber, the surface of bead wire was covered with coumarone resin coating or chlorinated natural rubber coating, and effects of two coatings on adhesion properties between bead wire and rubber were studied, vulcanization adhesion interface between bead wire and rubber was studied by experiment. Chlorinated natural rubber, nitrile rubber, ethylene methyacrylic acid copolymer were added to the traditional bead rubber of radial tire, and effects of these three polar polymers on vulcanization characteristics, mechanical properties, adhesion properties were studied, meanwhile effects of different size carbon blacks, NR/SBR blending ratio on properties of bead rubber were studied.The results are as follows: Highly purified coumarone resins with narrow molecular weight distribution were used as coating of bead wire, adhesion property between bead wire and rubber was better. Compared with uncoated bead wire, adhesion properties between bead wires and Aeolus, Sailun, Hankook bead rubbers were improved obviously by coatings(main components: Chlorinated natural rubber, phenolic resin), after hygrothermal aging or thermo-oxidative aging, adhesion properties of bead wire and bead rubber remained at higher level. The adhesion properties between coating bead wire and bead rubber were more outstanding when few cobalt salt was added to coating.The surface of coppered bead wire became rough after “squalene” simulated vulcanization experiment, many spherical convex structures were formed, which were formed by reactions of sulfur, copper, squalene and contains more iron, sulfur, copper. After “filter-paper” vulcanization experiment, the changes of superficial structures and elements of bead wire were similar to “squalene” simulated vulcanization experiment. In summary, bead wire-coating-rubber vulcanization bonding mechanism is as follows: In the process of vulcanization adhesion, bead wire and rubber were adhered together closely by coating, and coating enhanced interaction between CuxS layer of bead wire and rubber, and increased adhension interphase adhesivity and strength.When nitrile rubber was added to bead rubber of radial tire, the degradation of bead rubber's mechanical properties was delayed, and the adhesion property between bead rubber and bead wire was improved, but the loss factor and dynamic heat production of bead rubber increased. The addition of CNR can improve adhesion property between bead wire and bead rubber, but the mechanical properties of bead rubber had different degree drop. Ethylene methyacrylic acid copolymer improved adhesion property between bead wire and rubber significantly, and enhanced mechanical properties of bead rubber. With the decrease of carbon black particle size, the mechanical properties of bead rubber were improved, the rubber coverage ratio of bead wire declined gradually, the pull-out forces of different copper/tin content bead wires were very different. With increase of SBR content and reduction of NR content, the adhesion properties between bead rubber and bead wire decreased gradually, the mechanical properties of bead rubber first decreased and then increased before aging, and mechanical properties increased gradually after aging.