Rubber-fiber composite material and rubber article using the same

Abstract

A rubber-fiber composite material of the present invention comprises a non-woven fabric and a rubber which coats the non-woven fabric. At least a part of the non-woven fabric is made of an organic fiber having a single fiber diameter of 10 to 35 μm, a fiber length of 30 to 100 mm and a tensile modulus of 50 GPa or higher. By the use of the non-woven fabric at least a part of which is made of the organic fiber having the above properties, a sufficient impregnation of rubber into the inside of the non-woven fabric is ensured to enable the production of the rubber-fiber composite material having a high stiffness. Using the rubber-fiber composite material of the present invention as the reinforcing material for rubber articles, the resultant rubber articles have enhanced stiffness, improved durability and reduced weight.

What is claimed is:  
     
         1 . A rubber-fiber composite material comprising a non-woven fabric and a rubber which coats the non-woven fabric, at least a part of the non-woven fabric being made of an organic fiber having a single fiber diameter of 10 to 35 μm, a fiber length of 30 to 100 mm, and a tensile modulus of 50 GPa or higher.  
     
     
         2 . The rubber-fiber composite material according to  claim 1 , wherein the non-woven fabric has a basis weight of 30 to 120 g/m 2 .  
     
     
         3 . The rubber-fiber composite material according to  claim 1  or  claim 2 , wherein the non-woven fabric has a ratio D 1 /D 2  of 2 or more, wherein D 1  is a thickness of the non-woven fabric when measured under a pressure of 10 gf/cm 2  (about 981 Pa), and D 2  is a thickness of the non-woven fabric when measured under a pressure of 200 gf/cm 2  (about 19,613 Pa).  
     
     
         4 . The rubber-fiber composite material according to any one of  claims 1  to  3 , wherein the organic fiber is at least one fiber selected from the group consisting of para-aramid fibers, polyolefin ketone fibers, polybenzazole fibers and polyimide fibers.  
     
     
         5 . The rubber-fiber composite material according to  claim 4 , wherein the organic fiber is at least one para-aramid fiber selected from the group consisting of copoly-p-phenylene-3,4′-oxydiphenylene terephthalamide and poly-p-phenylene terephthalamide.  
     
     
         6 . A rubber article reinforced with the rubber-fiber composite material as set forth in any one of  claims 1  to  5 .  
     
     
         7 . A tire reinforced with the rubber-fiber composite material as set forth in any one of  claims 1  to  5 .  
     
     
         8 . A safety pneumatic tire comprising a tire assembly having: 
 (A) a tubeless tire comprising an annular tread having a pair of sidewalls respectively extending radially inwardly from opposite ends of the tread, and beads each embedded in a radially inner end of the sidewall;    (B) a tube disposed within the tubeless tire; and    (C) a reinforcing layer covering at least a top portion of the tube,    wherein a space is formed between an outer surface of the tube and an inner surface of a crown portion of the tubeless tire in inflated conditions;    wherein the reinforcing layer is disposed so as to extend radially outwardly to come into close contact with an inner surface of the tread of the tubeless tire when an inner pressure of the tire decreases, thereby enabling run-flat running; and    wherein the reinforcing layer is made of a rubber-fiber composite material comprising a non-woven fabric and a rubber, at least a part of the non-woven fabric being made of an organic fiber having a single fiber diameter of 10 to 35 μm and a tensile modulus of 50 GPa or higher.    
     
     
         9 . The safety pneumatic tire according to  claim 8 , wherein the organic fiber has a fiber length of 30 to 100 mm.  
     
     
         10 . The safety pneumatic tire according to  claim 8  or  9 , wherein the organic fiber is para-aramid fiber.  
     
     
         11 . The safety pneumatic tire according to  claim 10 , wherein the para-aramid fiber is contained in an amount of 50% by weight or more based on the total weight of the organic fiber constituting the non-woven fabric.  
     
     
         12 . The safety pneumatic tire according to  claim 10  or  11 , wherein the para-aramid fiber is copoly-p-phenylene-3,4′-oxydiphenylene terephthalamide or poly-p-phenylene terephthalamide.  
     
     
         13 . The safety pneumatic tire according to any one of  claims 8  to  12 , wherein the non-woven fabric has a basis weight of 30 to 120 g/m 2 .  
     
     
         14 . The safety pneumatic tire according to any one of  claims 8  to  13 , wherein the non-woven fabric has a ratio D 1 /D 2  of 2 or more, wherein D 1  is a thickness of the non-woven fabric when measured under a pressure of 10 gf/cm 2  (about 981 Pa), and D 2  is a thickness of the non-woven fabric when measured under a pressure of 200 gf/cm 2  (about 19,613 Pa).  
     
     
         15 . The safety pneumatic tire according to any one of  claims 8  to  14 , wherein the non-woven fabric has a thickness of 0.2 to 1.4 mm when measured under a pressure of 20 gf/cm 2  (about 1,961 Pa).  
     
     
         16 . The safety pneumatic tire according to any one of  claims 8  to  15 , wherein the reinforcing layer is made of a laminate having 3 to 6 layers of the rubber-fiber composite material.  
     
     
         17 . The safety pneumatic tire according to any one of  claims 8  to  16 , wherein an inner pressure of the tube is kept 20 to 100 kPa higher than that of the tire.