Processes for molding pulp paper containers and lids

Abstract

A process for molding recyclable, compostable, and disposable containers made of pulp paper is disclosed herein. The process includes disposing a wet pulp layer on a male or female mold, mating the mold with its counterpart, and applying a force on the pulp layer to remove moisture and thin the pulp. The process continues by applying a vacuum to either the male or female mold to hold the pulp layer, and removing the other mold. The process further comprises sequentially mating male and female molds until the pulp layer is the desired thickness and shape of the container. Embodiments of the process may include molding pulp containers to include pleats, stability features, reverse draft features, and puffed pulp configurations.

1 . A process for making a molded pulp container comprising:
 disposing a pulp layer on a first mold;   mating a second male mold with the first mold, the first and second molds being separated by a first offset and configured to exert a compressive force on the pulp layer to remove moisture and thin the pulp layer;   drawing a vacuum through the second mold, the vacuum being configured to hold the pulp layer against the second mold;   removing the first mold from the second mold and the pulp layer;   mating a third mold with the second mold, the second and third molds being separated by a second offset, less than the first offset and configured to exert a compressive force on the pulp layer to further thin the pulp layer;   drawing a vacuum through one of the second and third molds, the vacuum being configured to hold the pulp layer against the one of the second and third molds; and   removing the other one of the second and third molds from the one of the second and third molds with the pulp layer thereon.   
     
     
         2 . The process of  claim 1  wherein the pulp layer is first disposed on a forming mold, mated with the first mold, and the forming mold is removed by drawing at least one of a vacuum through the first mold and pressurized air through the forming mold. 
     
     
         3 . The process of  claim 1 , further comprising:
 applying pressurized air through at least one of the first and third molds when they are removed from the second mold.   
     
     
         4 . The process of  claim 1  wherein the first offset is greater in upper portions of the first and second molds and smaller in lower portions of the first and second molds, the process further comprising:
 varying the portions of subsequent male and female molds having a greater offset; and   decreasing the size of subsequent offsets.   
     
     
         5 . The process of  claim 1 , further comprising:
 repeating the mating and removing of subsequent molds until the container is a desired thickness and shape.   
     
     
         6 . The process of  claim 1 , further comprising:
 repeating the mating and removing of subsequent molds;   alternating the mold on which the vacuum operates to hold the pulp layer.   
     
     
         7 . The process of  claim 1 , further comprising:
 mating a fourth mold with the second mold, the pulp layer having a portion extending beyond the fourth mold;   drawing a vacuum through the fourth mold, the vacuum being configured to hold the pulp layer against the fourth mold;   removing the second mold;   mating a fifth mold with the fourth mold, the fifth mold having an upper portion configured to mold the portion of the pulp layer extending beyond the fourth mold at least partially against the fourth mold; and   repeating the mating and removal of subsequent mating molds configured to mold the portion of the pulp extending beyond the fourth mold at least partially against the subsequent mating molds.   
     
     
         8 . The process of  claim 1  wherein first, second and third molds each have a draft angle, the draft angle configured to prevent the pulp layer from tearing when it is removed from at least one of the first, second and third molds. 
     
     
         9 . The process of  claim 1  wherein first, second and third molds have at least one indentation configured to form at least one pleat on the container. 
     
     
         10 . The process of  claim 1  wherein the first, second and third molds have a plurality of indentations configured to form a plurality of pleats on a circumference of the pulp layer, the process further comprising:
 molding a plurality of pleats about a circumferential portion of the pulp layer, wherein at least a portion of the pleats provides a reverse draft feature positioned at a negative draft angle.   
     
     
         11 . The process of  claim 10  wherein at least one of the first, second and third molds has a reverse draft portion with a greater porosity and a greater offset than the remainder of the mold, the reverse draft portion being configured to create a less dense pulp portion. 
     
     
         12 . The process of  claim 1  wherein the first, second and third molds are configured to imprint a pattern onto the pulp layer. 
     
     
         13 . The process of  claim 1  wherein first, second and third molds include angular lower portions, the angular lower portions configured to form stability features on the paper container. 
     
     
         14 . The process of  claim 1 , further comprising:
 heating at least one of the first, second and third molds during mating.   
     
     
         15 . The process of  claim 1 , further comprising:
 heating at least one of the first, second and third molds while a vacuum is applied to hold the pulp layer against it; and   applying a coating to the pulp layer.   
     
     
         16 . A method of manufacturing a pulp paper cup, the method comprising:
 disposing a pulp layer on a female mold;   mating a male mold with the female mold, the female mold and the male mold having a first offset, wherein the first offset is the distance between the male and the first female mold and the first offset is non-homogeneous and is configured to apply a greater force on a first portion of the pulp layer;   applying a vacuum to the male mold, the vacuum being configured to hold the pulp layer against the first male mold;   removing the female mold, the female mold and male mold having a draft angle positioned between them and configured to prevent tearing of the pulp layer during removal of the female mold;   mating a second female mold with the male mold, the second female mold creating a second offset, less than the first offset, the second offset is non-homogenous and is configured to apply a greater force on a second portion of the pulp layer, different than the first portion of the pulp layer; and   removing the pulp layer from the male mold and the second female mold.   
     
     
         17 . The method of  claim 16 , further comprising:
 providing a straight assembly line of sequential female molds; and   repeating the mating of subsequent female molds with the male mold along the straight assembly line until the pulp layer is the desired thickness and shape.   
     
     
         18 . The method of  claim 16 , further comprising:
 providing a circular manufacturing tool comprising male and female molds with sequentially smaller offsets; and   repeating the mating of subsequent male and female molds until the pulp layer is the desired thickness and shape.   
     
     
         19 . A process for manufacturing a molded pulp paper container having a reverse draft feature, the process comprising:
 disposing a pulp layer on a first female mold;   mating a first male mold with the first female molds, the first male and female molds being separated by a first offset and having reverse draft portions with plurality of indentations configured to form a plurality of pleats on the pulp layer;   applying a vacuum to the first male mold, the vacuum being configured to hold the pulp layer against the first female mold;   removing the first female mold;   mating a second female mold with the first male mold;   applying a vacuum to the second female mold, the vacuum being configured to hold the pulp layer against the second female mold;   removing the first male mold;   mating a second male mold with the first female molds, the second male and female molds separated by an offset, smaller than the first offset, and having reverse draft portions configured an angular distance away from the draft;   repeating the mating and removal of subsequent male and female molds until a portion of the pulp layer has a reverse draft feature, positioned at a negative draft angle;   removing final male and female molds, wherein removing the molds expands the circumference of the paper container; and   collapsing the paper container at the pleats to form the reverse draft feature.