Method of bonding fluororesin films, and fluororesin film

Abstract

A method for bonding fluororesin films, a wide fluororesin film obtained by the method, and a covering material for agricultural use, made thereof, are presented. A method of bonding films (A), wherein two sheets of films (A) made of a fluororesin, are disposed so that their edges overlap each other, a central part (b 1 ) of the overlapping portion (B) is press-bonded under heating at a temperature within a range of from lower by 5° C. to higher by 20° C. than the melting point of the fluororesin, and then the entire area of the portion (B) is press-bonded at a temperature within a range of from lower by 30° C. to lower by more than 5° C., than the melting point, to weld the two sheets of films (A); a wide fluororesin film obtained by the method; and a covering material for agricultural use, made thereof.

1 . A method of bonding fluororesin films, which is a method of bonding films (A) made of a fluororesin, characterized in that two sheets of films (A) are disposed so that their edges overlap each other, a central part (b 1 ) of the overlapping portion (B) is press-bonded under heating at a temperature within a range of from lower by 5° C. to higher by 20° C. than the melting point of the fluororesin, and then the entire area of the portion (B) is press-bonded at a temperature within a range of from lower by 0° C. to lower by more than 5° C., than the melting point, to weld the two sheets of films (A).  
     
     
         2 . The bonding method according to  claim 1 , characterized in that after being welded, the films (A) are cooled.  
     
     
         3 . A method of bonding fluororesin films, which is a method of bonding films (A) made of a fluororesin, characterized in that two sheets of films (A) are disposed so that their edges overlap each other to form an overlapping portion (B), then a film (C) made of a fluororesin is disposed so that it overlaps on the overlapping portion (B), then a central part (b 1 ) of the overlapping portion (B) is press-bonded from above the film (C) under heating at a temperature within a range of from lower by 5° C. to higher by 20° C. than the melting point of the fluororesin, and then the overlapping portion (B) and the film (C) are press-bonded at a temperature within a range of from lower by 30° C. to lower by more than 5° C., than the melting point, to weld the two sheets of films (A) and the film (C).  
     
     
         4 . The bonding method according to  claim 3 , characterized in that after being welded, the films (A) and the film (C) are cooled.  
     
     
         5 . The bonding method according to  claim 1 , characterized in that the films (A) made of a fluororesin, are films (A) made of a fluororesin, having a hydrophilic surface-treatment layer (D) on one side, and no hydrophilic surface-treatment layer is formed on the surface to be welded at the overlapping portion (B) of one of the films (A).  
     
     
         6 . The bonding method according to  claim 3 , characterized in that the films (A) made of a fluororesin, are films (A) made of a fluororesin, having a hydrophilic surface-treatment layer (D) on one side, and no hydrophilic surface-treatment layer is formed on the surface to be welded at the overlapping portion (B) of one of the films (A).  
     
     
         7 . The bonding method according to  claim 1 , wherein the films (A) are films made of an ethylene/tetrafluoroethylene copolymer.  
     
     
         8 . The bonding method according to  claim 3 , wherein the films (A) are films made of an ethylene/tetrafluoroethylene copolymer.  
     
     
         9 . The bonding method according to  claim 1 , wherein the width of the overlapping portion is from 5 to 100 mm.  
     
     
         10 . The bonding method according to  claim 3 , wherein the width of the overlapping portion is from 5 to 100 mm.  
     
     
         11 . The bonding method according to  claim 1 , wherein the width of the central part (b 1 ) is from 1 to 50 mm.  
     
     
         12 . The bonding method according to  claim 3 , wherein the width of the central part (b 1 ) is from 1 to 50 mm.  
     
     
         13 . A wide fluororesin film having a width of from 1 to 150 m, having at least two sheets of films (A) bonded by repeating the bonding method as defined in  claim 1 , at least once.  
     
     
         14 . A wide fluororesin film having a width of from 1 to 150 m, having at least two sheets of films (A) bonded by repeating the bonding method as defined in  claim 3 , at least once.  
     
     
         15 . A covering material for agricultural use, made of the wide fluororesin film as defined in  claim 13 .  
     
     
         16 . A covering material for agricultural use, made of the wide fluororesin film as defined in  claim 14 .  
     
     
         17 . A material for a film structure, made of the wide fluororesin film as defined in  claim 13 .  
     
     
         18 . A material for a film structure, made of the wide fluororesin film as defined in  claim 14.