Fuel hose and method of its production

Abstract

The fuel hose of this invention is a fuel hose comprising a tubular fluororesin inner ply and, as laminated onto the peripheral surface thereof, a thermoplastic resin or rubber outer ply, the tubular fluororesin inner ply having been molded from a fluororesin with an F/C ratio, i.e. ratio of the number of fluorine atoms (F) to the number of carbon atoms (C), of not greater than 1.6 and the peripheral surface layer of the fluororesin inner ply having been modified into the following treated layer (A).(A) a layer with a distribution of oxygen atoms and having an F/C ratio, i.e. ratio of the number of fluorine atoms (F) to the number of carbon atoms (C), of not greater than 1.12 and an O/C ratio, i.e. ratio of the number of oxygen atoms (O) to the number of carbon atoms (C), of not less than 0.08.In this fuel hose of the invention, the treated layer (A) of the tubular fluororesin inner ply has a remarkably increased adhesive affinity for thermoplastic resin and rubber, with the result that the bond strength between the tubular fluororesin inner ply and the thermoplastic resin or rubber outer layer is as high as not less than 1.2 N/mm.

What is claimed is:  
     
       1. A fuel hose comprising a tubular fluororesin inner ply having an F/C ratio ≦1.6, the outer surface of which is modified to have an oxygen-containing layer having an F/C ratio of ≦1.12, and an O/C ratio of ≧0.08; and a tubular rubber or thermoplastic resin outer ply; wherein the inner surface of the outer ply is laminated directly onto the outer surface of the inner ply and wherein the initial bond strength of the laminate between the inner and outer plies is not less than 1.2 N/mm. 
     
     
       2. A fuel hose according to  claim 1 , wherein the outer surface of the inner ply was modified by a vacuum plasma treatment. 
     
     
       3. A fuel hose according to  claim 1  or  2 , wherein the thermoplastic resin is a polyamide resin. 
     
     
       4. A fuel hose according to  claim 1  or  2 , wherein the thickness of the inner ply is 0.05-1.00 mm. 
     
     
       5. A fuel hose according to  claim 1  or  2 , wherein the tubular fluororesin inner ply is electrically conductive. 
     
     
       6. A fuel hose according to  claim 5 , wherein the tubular fluororesin inner ply is a multi-layer ply at least one layer of which is electrically conductive. 
     
     
       7. A fuel hose comprising a tubular fluororesin inner ply having an F/C ratio of >1.6≦2.0, the outer surface of which is modified to have an oxygen-containing layer having an F/C ratio of 0.8-1.8 and an O/C ratio of >0.2 minus 0.09 times the F/C ratio;  which is within the combination of the following two relationships ( a )  and  ( b ); 
       ( a )  when F/C is less than  0 . 8 , then O/C must be not less than  0 . 08 ; and    
       ( b )  when F/C is in the range F/C= 0 . 8  to  1 . 8 , then O/C must satisfy the relationship:    
       
         
             O/C> 0 . 2 − 0 . 09 × ( F/C ); 
         
       
       and a tubular rubber or thermoplastic resin outer ply; wherein the inner surface of the outer ply is laminated directly onto the outer surface of the inner ply and wherein the initial bond strength of the laminate between the inner and outer plies is not less then 1.2 N/mm. 
     
     
       8. A fuel hose according to  claim 7 , wherein the outer surface layer of the inner tubular ply was modified by a vacuum plasma treatment. 
     
     
       9. A fuel hose according to  claim 7  or  8 , wherein the thermoplastic resin is a polyamide resin. 
     
     
       10. A fuel hose according to  claim 7  or  8 , wherein the thickness of the inner ply is 0.05-1.00 mm. 
     
     
       11. A fuel hose according to  claim 7  or  8 , wherein the tubular fluororesin inner ply is electrically conductive. 
     
     
       12. A fuel hose according to  claim 11 , wherein the tubular fluororesin inner ply is a multi-layer ply at least one layer of which is electrically conductive. 
     
     
       13. A fuel hose according to claims  1 ,  2 ,  7  or  8 , which further comprises a rubber or elastomer sheath overlying the outer surface of the outer ply. 
     
     
       14. A fuel hose according to any of claims  1 ,  2 ,  7  or  8 , which further comprises a reinforcing cord ply between the rubber or elastomer sheath and the outer surface of the outer ply. 
     
     
       15. A method of producing a fuel hose comprising a rubber or thermoplastic resin outer ply laminated directly onto a tubular fluororesin inner ply, which comprises: extrusion-molding a tubular fluororesin, modifying the outer surface of the tubular fluororesin by a vacuum plasma treatment, and extrusion-molding a rubber or thermoplastic resin directly onto the modified surface of the tubular inner ply, wherein the fluororesin has an F/C ratio of ≦ 1 . 6 , and the modified outer surface of the tubular fluororesin has an F/C ratio of ≦ 1 . 12  and an O/C ratio of ≧ 0 . 08 . 
     
     
       16. A method of producing a fuel hose according to  claim 15 , wherein the fluororesin has an F/C ratio of ≦1.6, and the modified outer surface of the tubular fluororesin has an F/C ratio of ≦1.12 and an O/C ratio of ≧0.08. 
     
     
       17. A method of producing a fuel hose according to  claim 15 ,  comprising a rubber or thermoplastic resin outer ply laminated directly onto a tubular fluororesin inner ply, which comprises: extrusion- molding a tubular fluororesin, modifying the outer surface of the tubular fluororesin by a vacuum plasma treatment, and extrusion - molding a rubber or thermoplastic resin directly onto the modified surface of the tubular inner ply,  wherein the fluororesin has an F/C ratio of >1.6≦2.0, and the outer modified surface of the tubular fluororesin contains oxygen and has an F/C ratio of 0.8-1.8 and an O/C ratio of >0.2 minus 0.09 times the F/C ratio  is within the combination of the following two relationships ( a )  and  ( b ); 
       ( a )  when F/C is less than  0 . 8 , then O/C must be not less than  0 . 08 ; and    
       ( b )  when F/C is in the range F/C= 0 . 8 - 1 . 8 , then O/C must satisfy the relationship:    
       
         
             O/C> 0 . 2 − 0 . 09 × ( F/C ).  
         
       
     
     
       18. The method of producing a fuel hose according to  claim 15 , wherein the thermoplastic resin outer ply is formed by melting a thermoplastic resin, extruding the molten thermoplastic resin onto the outer surface of the tubular inner ply, and cooling the extruded thermoplastic resin to solidify and adhere the thermoplastic resin to the outer surface of the tubular inner ply. 
     
     
       19. A method of producing a fuel hose according to  claim 15 , wherein the thermoplastic resin is a polyamide resin. 
     
     
       20. A method of producing a fuel hose according to  claim 15 , wherein the thickness of the inner ply is 0.05-1.00 mm. 
     
     
       21. The method of producing a fuel hose according to  claim 17 , wherein the thermoplastic resin outer ply is formed by melting a thermoplastic resin onto the outer surface of the tubular inner ply, and cooling the extruded thermoplastic resin to solidify and adhere the thermoplastic resin to the outer surface of the tubular inner ply. 
     
     
       22. A method of producing a fuel hose according to  claim 17 , wherein the thermoplastic resin is a polyamide resin. 
     
     
       23. A method of producing a fuel hose according to  claim 17 , wherein the thickness of the inner ply is  0 . 05 - 1 . 00  mm.