Sealable card based container and blank therefor

Abstract

A card based container has a tubular sidewall of laminate material and first and second end closures, sealed to the tubular sidewall to form a hermetically sealed package. The sidewall has an outer card layer, an inner hygienic layer and one or more sealing strips provided at an inner surface of the inner hygienic layer, located at connection locations where the sidewall seals to itself or to the respective end closures. The sealing strips include a heat-sealable polymer. The overall amount of non-paper content in the sidewall and in the package may thus be reduced.

1 . A card based container comprising a sidewall of laminate material and first and second end closures, sealed to the tubular sidewall to form a hermetically sealed package, wherein the sidewall comprises:
 an outer structural layer comprising predominantly cellulose material;   an inner hygienic layer comprising a layer of food quality polymer material having a thickness of between 2 microns and 20 microns; and   one or more sealing strips provided at an inner surface of the sidewall, located at connection locations where the sidewall seals to itself or to the respective end closures, the sealing strips comprising a heat-sealable polymer.   
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . The container according to  claim 1 , wherein the outer structural layer has a weight of between 100 g/m2 and 500 g/m2. 
     
     
         5 . The container according to  claim 1 , wherein the sidewall comprises greater than 95% cellulose pulp content. 
     
     
         6 . The container according to  claim 1 , comprising an oxygen barrier layer. 
     
     
         7 . The container according to  claim 6 , wherein the oxygen barrier layer is a polymeric layer exhibiting an oxygen transmission rate of less than 0.1 cc/m2·day. 
     
     
         8 . The container according to  claim 1 , wherein the outer structural layer is a laminate comprising at least one layer of card material. 
     
     
         9 . The container according to  claim 1 , wherein the sealing strips have a thickness of between 30 microns and 200 microns. 
     
     
         10 . The container according to  claim 1 , wherein the sealing strips have a width of between 3 mm and 30 mm. 
     
     
         11 . The container according to  claim 1 , wherein the sealing strips cover between 4% and 20% of the area of the sidewall. 
     
     
         12 . The container according to  claim 1 , wherein one or both of the end closures comprises an outer structural layer and an inner hygienic layer. 
     
     
         13 . The container according to  claim 1 , wherein the sidewall is tubular and comprises a longitudinal seal extending from the first end closure to the second end closure. 
     
     
         14 . The container according to  claim 1 , wherein the sidewall has an upper rim that is rolled over and a sealing strip is provided around the upper rim. 
     
     
         15 . The container according to  claim 13 , wherein the first or second end closure is applied across and sealed to the upper rim. 
     
     
         16 . A method of manufacturing a card based container, the method comprising:
 providing a blank of laminate material having longitudinal edges and upper and lower edges, the laminate material comprising an outer structural layer comprising predominantly cellulose material and an hygienic layer at an inner side of the blank,   applying one or more sealing strips of heat-sealable polymer to the inner side of the blank,   rolling the blank with the hygienic layer facing inwards and connecting the longitudinal edges together to form a sidewall having first and second ends;   closing the first end with a first end closure;   filling the container with product through the second end; and   sealing the container by applying a second end closure to the second end whereby connecting, closing and/or sealing takes place by heat sealing the strip of heat-sealable polymer.   
     
     
         17 . The method of  claim 16 , wherein a longitudinal sealing strip is applied to one of the longitudinal edges and the longitudinal edges are connected in an overlap seam. 
     
     
         18 . The method of  claim 16 , wherein a lower sealing strip is applied to the lower edge of the blank and the first or second end closure is heat-sealed to the lower edge of the blank. 
     
     
         19 . The method of  claim 16 , wherein the heat-sealed lower edge is rolled over inwards such that the container can stand on a lower rim of card material. 
     
     
         20 . The method of  claim 16 , comprising applying a sealing strip at or adjacent to the upper edge of the blank, rolling over the upper edge of the blank to form an upper rim with the sealing strip uppermost and sealing the first or second end closure across the upper rim. 
     
     
         21 . A blank of card based laminate material for forming a container for oxygen sensitive food materials, the blank comprising an outer structural layer comprising predominantly cellulose material, an inner hygienic layer and an oxygen barrier layer, wherein sealing strips of heat-sealable polymer material are provided at an inner surface of the blank at sealing locations such that the blank can be sealed to itself or to another component to form the container. 
     
     
         22 . The blank of  claim 21 , wherein the inner hygienic layer comprises a layer of food quality polymer material having a thickness of between 2 microns and 20 microns; and the sealing strips comprise a heat-sealable polymer having a thickness greater than that of the inner hygienic layer.