Biodegradable molding

Abstract

A bowl-shaped container ( 10 a ) which is as a biodegradable molded article adheres a coating film ( 12 ) mainly made of biodegradable plastic and having at least hydrophobicity to the surface of the main body ( 11 a ) of the container mainly made of starch. The main body ( 11 a ) is molded through steam expansion of a slurry or dough molding material containing high-amylose starch and water, or a slurry or dough molding material containing starch, polyvinyl alcohol and water. For these reasons, it is possible to accomplish sufficient strength and at least sufficient water resistance, to exert a very excellent biodegradability and further to provide a biodegradable molded article having excellent moisture absorption strength mainly made of starch even if the biodegradable molded article has a complicated shape.

1 . A biodegradable molded article comprising: 
 a biodegradable expanded molded article molded in a specified shape; and    a coating film attached to a surface of the biodegradable expanded molded article, the film being mainly made of a biodegradable plastic and having at least hydrophobicity,    the biodegradable expanded molded article being molded, through steam expansion, from a slurry or dough molding material mainly made of a starch and a derivative thereof and prepared by adding water to the starch or the derivative thereof,    the starch and the derivative thereof containing high-amylose starch or a derivative thereof.    
     
     
         2 . The biodegradable molded article as set forth in  claim 1 , wherein the starch and a derivative thereof contains not less than 50 weight % high-amylose starch or a derivative thereof.  
     
     
         3 . A biodegradable molded article comprising: 
 a biodegradable expanded molded article molded in a specified shape; and    a coating film attached to a surface of the biodegradable expanded molded article, the film being mainly made of a biodegradable plastic and having at least hydrophobicity,    said biodegradable expanded molded article being molded, through steam expansion, from a slurry or dough molding material mainly made of a starch and a derivative thereof and prepared by adding water and polyvinyl alcohol to the starch or the derivative thereof.    
     
     
         4 . The biodegradable molded article as set forth in  claim 3 , wherein the polyvinyl alcohol has a polymerization degree of not less than 1500.  
     
     
         5 . The biodegradable molded article as set forth in  claim 3 , wherein the polyvinyl alcohol has a saponification degree of not less than 75%.  
     
     
         6 . The biodegradable molded article as set forth in  claim 1 , wherein the coating film is mainly made of a modified polyester.  
     
     
         7 . The biodegradable molded article as set forth in  claim 1 , wherein the coating film is biaxially stretched.  
     
     
         8 . The biodegradable molded article as set forth in  claim 1 , wherein the molding material further contains a water-insoluble fiber.  
     
     
         9 . The biodegradable molded article as set forth in  claim 1 , wherein the expanded molded article accounts for not less than 60 weight % of total weight of the biodegradable molded article.  
     
     
         10 . The biodegradable molded article as set forth in  claim 1 , wherein the molding material contains water which accounts for 20 weight % to 70 weight %, assuming that the biodegradable molded article is 100 weight %.  
     
     
         11 . The biodegradable molded article as set forth in  claim 1 , wherein the coating film is directly and substantially adhered to the surface.  
     
     
         12 . The biodegradable molded article as set forth in  claim 1 , wherein the biodegradable expanded molded article has a final water content between 3 weight % and 20 weight %.  
     
     
         13 . The biodegradable molded article as set forth in  claim 4 , wherein the polyvinyl alcohol has a saponification degree of not less than 75%.  
     
     
         14 . The biodegradable molded article as set forth in  claim 3 , wherein the coating film is mainly made of a modified polyester.  
     
     
         15 . The biodegradable molded article as set forth in  claim 3 , wherein the coating film is biaxially stretched.  
     
     
         16 . The biodegradable molded article as set forth in  claim 3 , wherein the molding material further contains a water-insoluble fiber.  
     
     
         17 . The biodegradable molded article as set forth in  claim 3 , wherein the expanded molded article accounts for not less than 60 weight % of total weight of the biodegradable molded article.  
     
     
         18 . The biodegradable molded article as set forth in  claim 3 , wherein the molding material contains water which accounts for 20 weight % to 70 weight %, assuming that the biodegradable molded article is 100 weight %.  
     
     
         19 . The biodegradable molded article as set forth in  claim 3 , wherein the coating film is directly and substantially adhered to the surface.  
     
     
         20 . The biodegradable molded article as set forth in  claim 3 , wherein the biodegradable expanded molded article has a final water content between 3 weight % and 20 weight %.