Production method for pulp foam cushioning material, shaping mold for the same, and pulp foam cushioning material

Abstract

Provided is a method for producing a pulp foam cushioning material in which unevenly dehydrated regions are reduced from those in prior art. The method for producing a pulp foam cushioning material includes the steps of mixing and kneading a pulp feedstock, composed of shredded pieces of a pulp raw material, with water and a foaming agent to obtain a foamy substance, filling a shaping mold (mold main body and an external frame unit) with an amount of the foamy substance that is greater than a volume of the pulp foam cushioning material, compressing the filled foamy substance, and dehydrating and drying the foamy substance. The shaping mold includes a mold main body entirely composed of a breathable material. In the drying step, the foamy substance is dehydrated and dried in a state where all surfaces of the foamy substance are surrounded by the mold main body.

1 . A method for producing a pulp foam cushioning material, the method comprising the steps of:
 mixing and kneading a pulp feedstock, composed of shredded pieces of a pulp raw material, with water and a foaming agent to obtain a foamy substance;   filling a shaping mold with an amount of the foamy substance that is greater than a volume of the pulp foam cushioning material;   compressing the filled foamy substance; and   drying and dehydrating the foamy substance, wherein   the shaping mold comprises a mold main body which is entirely composed of a breathable material; and   in the drying step, the foamy substance is dried and dehydrated in a state where all surfaces of the foamy substance are surrounded by the mold main body.   
     
     
         2 . The method for producing a pulp foam cushioning material according to  claim 1 , further comprising, between the filling step and the compressing step, a step of inserting a mesh panel between the shaping mold and the foamy substance. 
     
     
         3 . A shaping mold for a pulp foam cushioning material, the shaping mold configured to be filled with a foamy substance obtained by mixing and kneading a pulp feedstock, composed of shredded pieces of a pulp raw material, with water and a foaming agent, wherein
 the shaping mold comprises a mold main body which is entirely composed of a breathable material.   
     
     
         4 . The shaping mold for a pulp foam cushioning material according to  claim 3 , wherein
 the mold main body is composed of a flexible material; and   the shaping mold comprises an external frame unit configured to hold a shape of the mold main body from outside the mold main body.   
     
     
         5 . The shaping mold for a pulp foam cushioning material according to  claim 3 , wherein
 the mold main body is composed of a plurality of divided sub parts.   
     
     
         6 . The shaping mold for a pulp foam cushioning material according to  claim 5 , wherein the plurality of sub parts comprises:
 a cross-shaped component including cross walls which divide a pulp foam cushioning material into four portions, wherein a through hole is formed at the center of the cross walls; and   a columnar component configured to be inserted into the through hole.   
     
     
         7 . The shaping mold for a pulp foam cushioning material according to  claim 6 ,
 wherein the mold main body comprises:
 an outer wall component being longer than the cross-shaped component and configured to surround the cross-shaped component; 
 a first lid component configured to be inserted into a filling space surrounded by the outer wall component, and placed on the cross-shaped component; and 
 a second lid component being thicker than the first lid component and configured to be stacked on the first lid component; wherein 
   after the filling space is filled with the foamy substance, the foamy substance is downwardly pushed in by the second lid component and the first lid component; and   after the foamy substance is pushed in, the second lid component is removed.   
     
     
         8 . The shaping mold for a pulp foam cushioning material according to  claim 7 , wherein the first lid component has water absorbency superior to water absorbency of the cross-shaped component and of the outer wall component. 
     
     
         9 . The shaping mold for a pulp foam cushioning material according to  claim 4 , further comprising a filling mechanism placed above both the mold main body and the external frame unit,
 wherein the filling mechanism comprises
 a sleeve configured to introduce the foamy substance into the mold main body from above; and 
 a piston configured to be inserted into the sleeve; wherein 
   the sleeve is composed of a water impermeable material, and   an inner wall surface of the sleeve is a smooth surface.   
     
     
         10 . The shaping mold for a pulp foam cushioning material according to  claim 7 , further comprising:
 a mesh panel configured to be inserted between the cross-shaped component and the first lid component.   
     
     
         11 . A pulp foam cushioning material obtained by mixing and kneading a pulp feedstock, composed of shredded pieces of a pulp raw material, with water and a foaming agent, the pulp foam cushioning material comprising:
 a core layer being a foamed layer; and   a skin layer covering all surfaces of the core layer,   wherein a density of fibers in the skin layer is higher than a density of fibers in the core layer.   
     
     
         12 . The pulp foam cushioning material according to  claim 11 , further comprising:
 a bottom wall; and   a plurality of side walls extending upward from the bottom wall and separated from each other, wherein   a central hole is defined by the bottom wall and the plurality of side walls;   the bottom wall comprises the core layer and the skin layer covering the core layer, while each of the plurality of side walls comprises the core layer and the skin layer covering the core layer; and   the core layer in the side wall has a cushioning property superior to a cushioning property of the core layer in the bottom wall.   
     
     
         13 . The pulp foam cushioning material according to  claim 12 , wherein
 a density of fibers in the core layer of the side wall is lower than a density of fibers in the core layer of the bottom wall.   
     
     
         14 . The pulp foam cushioning material according to  claim 13 , wherein
 the side wall is thicker than the bottom wall.