Pulp molded lid with non-reticulated inner and outer surfaces and process of manufacturing same

Abstract

A process of manufacturing a pulp molded cup lid includes making a pulp slurry; distributing the pulp onto a continuous screen wherein the pulp slurry is converted into a blank; feeding the blank and the continuous screen onto a first blanking die; moving a first blanking punch onto the first blanking die to dry the blank at a temperature of 160-180° C. for 2-5 seconds; causing the first blanking punch to exert pressure of 27-40 N/cm 2 on the blank for 8-20 seconds; conveying the blank onto a second blanking die which is disposed under a second blanking punch; drying the blank, the second blanking punch, and the second blanking die at a temperature of 160-180° C.; moving the second blanking punch onto the second blanking die in 2-8 seconds; and causing the second blanking punch to exert pressure of 80-120 N/cm 2 on the blank for 30-45 seconds.

What is claimed is: 
     
         1 . A pulp moulded cup lid, the cup lid having smooth, non-reticulated inner and outer surfaces, comprising:
 a lid body ( 1 );   a sealing skirt ( 4 ) axially extending downward the lid body; and   a plurality of buckling projections ( 5 ) disposed evenly and circumferentially on an outer surface of a lower portion of the sealing skirt ( 4 );   wherein the lid body has smooth, non-reticulated inner and outer surfaces.   
     
     
         2 . The pulp moulded cup lid of  claim 1 , wherein a number of the buckling projections ( 5 ) is 8-16. 
     
     
         3 . The pulp moulded cup lid of  claim 1 , wherein the buckling projections ( 5 ) are elongated ribs protruding inward the sealing skirt ( 4 ). 
     
     
         4 . The pulp moulded cup lid of  claim 3 , wherein each of the elongated ribs has a projection height of 1.5 to 2.0 mm. 
     
     
         5 . The pulp moulded cup lid of  claim 1 , further comprising a plurality of reinforcing ribs ( 7 ) which are set on an outer surface of a dispensing window ( 3 ) of the lid body ( 1 ). 
     
     
         6 . The pulp moulded cup lid of  claim 5 , wherein the reinforcing ribs ( 7 ) are bump in an evenly spaced arrangement. 
     
     
         7 . The pulp moulded cup lid of  claim 1 , further comprising a convex platform ( 2 ) set along the circumferential direction on the outer periphery of the lid body ( 1 ); and a dispensing window ( 3 ) set on the convex platform ( 2 ); the dispensing window ( 3 ) is either open or provided with a clamshell type cover. 
     
     
         8 . The pulp moulded cup lid of  claim 7 , wherein the lid body ( 1 ) further comprises a concave groove ( 6 ) disposed adjacent to the dispensing window ( 3 ). 
     
     
         9 . A method of manufacturing pulp moulded cup lids with non-reticulated surfaces comprising the following steps:
 (1) diluting plant fibers in water to make a pulp slurry;   (2) filling the pulp slurry into a forming mould with a filtering screen for vacuum absorption moulding to become a blank, wherein the blank has a water content of 65-75 wt %;   (3) closing a transfer mould (blank punch) at temperature of 160-180° C. and the forming mould to form a closed mould set with no pressure exerted on the blank for 2-5 seconds; then applying a pressure up to 27-40 N/cm 2  on the blank through the closed mould set for 8-20 seconds; wherein when this step is completed, the blank has a total water content of 50-55 wt %, while a side contacting the filtering screen has a water content of 58-65 wt %; and   (4) moving the blank into a set of heat setting drying moulds with upper and lower moulds at temperature of 160-180° C.; closing the two moulds together with no pressure applied for 2-8 seconds; then, applying a pressure of up to 80-120 N/cm 2  on the blank for 30-45 seconds.   
     
     
         10 . The method of  claim 9 , wherein:
 in step (2), the blank has a 70 wt % water content;   in step (3), the transfer mould (blank punch) has a temperature of 170° C. and the two moulds are closed together for 3 seconds with no pressure exerted;   then, a pressure of up to 33 N/cm 2  is applied on the blank for 15 seconds; the resulting blank has a total water content of 50-55 wt %, while the side contacting the filtering screen has the water content of 58-65 wt %;   in step (4), the temperature of the upper and lower moulds is 170° C.; the two moulds are closed together with no pressure applied for 3 seconds, then, a pressure of up to 97 N/cm 2  is applied on the blank for 38 seconds.