Molded pulp product, and method and apparatus for production thereof

Abstract

A pulp molded article having a pulp fiber layer ( 2 ) of single layer structure which is formed by papermaking from a single raw material composition and has a density distribution in the thickness direction thereof. The pulp fiber layer ( 2 ) has such a density distribution that the density increases or decreases in the thickness direction thereof.

1 . A pulp molded article having a pulp fiber layer of single layer structure which is formed by papermaking from a single raw material composition and has a density distribution in the thickness direction thereof.  
     
     
         2 . The pulp molded article according to  claim 1 , wherein said pulp fiber layer has a density distribution such that the density increases or decreases in the thickness direction thereof.  
     
     
         3 . The pulp molded article according to  claim 1 , wherein at least one of the inner surface and the outer surface of said pulp fiber layer is coated with a coating layer.  
     
     
         4 . The pulp molded article according to  claim 1 , wherein the outer surface of said pulp fiber layer is coated with another pulp fiber layer.  
     
     
         5 . The pulp molded article according to  claim 4 , wherein said another pulp fiber layer has a density higher than the highest density of said pulp fiber layer.  
     
     
         6 . The pulp molded article according to  claim 1 , wherein said pulp fiber layer and said coating layer are each made from a biodegradable material.  
     
     
         7 . The pulp molded article according to  claim 1 , wherein said pulp fiber layer is the main body of a cup-shaped container and has a flange around the brim of the main body.  
     
     
         8 . The pulp molded article according to  claim 7 , wherein the body portion of said main body is provided with said density distribution.  
     
     
         9 . The pulp molded article according to  claim 7 , wherein said flange and the bottom portion of said main body has a higher density than the body portion of said main body.  
     
     
         10 . A method of producing a pulp molded article comprising a papermaking and dewatering step in which a pulp fiber layer is made from a single raw material composition by papermaking and dewatered and a drying step in which the dewatered pulp fiber layer is fitted into a drying mold and dried while creating a density distribution in the thickness direction thereof, wherein: 
 said drying mold has evacuation holes connecting to the outside on the inner wall thereof in the portion corresponding to the portion of said pulp fiber layer where a density distribution is not to be created,    said pulp fiber layer fitted in said drying mold is pressed onto the inner wall of said drying mold by an elastically deformable pressing member, while the drying mold is forcibly evacuated through said evacuation holes,    the pressing force by said pressing member is reduced and, the evacuation through said evacuation holes is stopped to separate said pressing member from said pulp fiber layer to obtain said pulp fiber layer provided with a density distribution in the thickness direction thereof.    
     
     
         11 . The method of producing a pulp molded article according to  claim 10 , wherein the step of pressing said pulp fiber layer by said pressing member and the step of reducing the pressing force of said pressing member and stopping the evacuation are repeated to dry said pulp fiber layer.  
     
     
         12 . The method of producing a pulp molded article according to  claim 10 , which further comprises a step of coating at least one of the inner surface and the outer surface of said pulp fiber layer with a coating layer.  
     
     
         13 . An apparatus for carrying out the method of producing a pulp molded article according to  claim 10 , which comprises a drying mold into which a pulp fiber layer is fitted and an elastically deformable pressing member which presses the pulp fiber layer fitted into said drying mold from the inside of the pulp fiber layer toward the inner wall of said drying mold, said drying mold having evacuation holes connecting to the outside on the inner wall thereof in the portion corresponding to the part of the pulp fiber layer where a density distribution is not to be created.