Process for heat sealing a water soluble film in the presence of water

Abstract

A process for heat sealing a water soluble film to a water soluble member, wherein an aqueous composition is applied to at least one of the surfaces of said film and said member before said surfaces are heat sealed together.

1 . A process for heat sealing a water soluble film to a water soluble member, wherein an aqueous composition is applied by printing or painting the composition to at least one of the surfaces of said film and said member before said surfaces are heat sealed together.  
     
     
         2 . A process according to  claim 1  wherein the water soluble film is a poly (vinyl alcohol) film.  
     
     
         3 . A process according to  claim 1  or  2  wherein the water soluble member is a poly (vinyl alcohol) member.  
     
     
         4 . A process according to  claim 2  or  3  wherein poly (vinyl alcohol) in the water soluble film and/or the water soluble member has a water content of less than 5 wt %.  
     
     
         5 . A process according to any one of the preceding claims wherein the aqueous composition is water.  
     
     
         6 . A process according to any one of  claims 1  to  4  wherein the aqueous composition is an aqueous solution of the polymer from which the water soluble film and/or water soluble member is made.  
     
     
         7 . A process according to any one of the preceding claims wherein the aqueous composition is applied to the surfaces of both said water soluble film and said water soluble, member.  
     
     
         8 . A process according to any one of the preceding claims wherein the aqueous composition is applied by a transfer printing process.  
     
     
         9 . A process according to claims  8  wherein the aqueous composition is applied by photogravure, litho, flexo, silk screen or recess printing process.  
     
     
         10 . A process according to any one of the preceding claims wherein the aqueous composition has a temperature of from to 10 to 40° C.  
     
     
         11 . A process according to any one of the preceding claims wherein the water soluble member is in the form of a film.  
     
     
         12 . A process according to  claim 11  wherein the water soluble member has been thermoformed.  
     
     
         13 . A process according to any one of  claims 1  to  10  wherein the water soluble member has been injection moulded.  
     
     
         14 . A process according to any one of the preceding claims wherein the heat sealing pressure is from 100 to 500 kPa (1 to 5 bar).  
     
     
         15 . A process according to any one of the preceding claims wherein the heat sealing temperature is from 100 to 180° C.  
     
     
         16 . A process according to any one of the preceding claims wherein the water soluble member is in the form of a pocket and a container which contains a composition is prepared.