Pneumatic tire and manufacturing method therefor

Abstract

Provided is a pneumatic tire and a manufacturing method therefor which allow a reduction in a cavity resonance sound without complicated manufacturing steps. A pneumatic tire of the present invention includes: a pair of bead portions; a carcass layer bridged between the pair of bead portions; and an inner liner layer disposed at a tire inner surface side of the carcass layer, the inner liner layer being made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending a thermoplastic resin with an elastomer. The inner liner layer has a laminated structure including multiple film layers having different melting points of the thermoplastic resin from each other. The film layer having the lowest melting point of the thermoplastic resin is foamed to form multiple convex portions in the tire inner surface.

What is claimed is: 
     
         1 . A manufacturing method for a pneumatic tire comprising the steps of:
 bridging a carcass layer between a pair of bead portions;   disposing an inner liner layer at a tire inner surface side of the carcass layer, the inner liner layer being made of any one of a thermoplastic resin and a thermoplastic elastomer composition that is obtained by blending a thermoplastic resin with an elastomer;   building an uncured tire in which the inner liner layer has a laminated structure including a plurality of film layers having different melting points of the thermoplastic resin from each other;   curing the uncured tire while pressurizing the tire from an inside thereof; and   in depressurizing the tire after the curing, foaming a film layer having a lowest melting point of the thermoplastic resin to thus form a plurality of convex portions in the tire inner surface.   
     
     
         2 . The manufacturing method for a pneumatic tire according to  claim 1 , wherein
 a film layer having a highest melting point of the thermoplastic resin has a melting point set in a range of 175° C. to 250° C., and   a difference in melting point between the film layer having the highest melting point of the thermoplastic resin and the film layer having the lowest melting point of the thermoplastic resin is 5° C. or larger.   
     
     
         3 . The manufacturing method for a pneumatic tire according to  claim 1 , wherein the film layer having the lowest melting point of the thermoplastic resin is kneaded with a filler. 
     
     
         4 . The manufacturing method for a pneumatic tire according to  claim 1 , wherein
 the film layer having the highest melting point of the thermoplastic resin is disposed closest to the carcass layer, and   the film layer having the lowest melting point of the thermoplastic resin is disposed farthest from the carcass layer.   
     
     
         5 . The manufacturing method for a pneumatic tire according to  claim 1 , wherein a rubber layer is disposed at a tire inner surface side of the inner liner layer. 
     
     
         6 . The manufacturing method for a pneumatic tire according to  claim 1 , wherein the film layer having the lowest melting point of the thermoplastic resin is disposed partially in a tire circumferential direction. 
     
     
         7 . The manufacturing method for a pneumatic tire according to  claim 1 , wherein the uncured tire is cured without a bladder.