Method and apparatus for blowmoding capsules of polyvinylalcohol and blowmolded polyvinylalcohol capsules

Abstract

A capsule is formed from a PVA composition by blow moulding. Such capsules can at last provide a viable alternative to gelatin for biodegradable capsules containing a pharmaceutical or consumable or other substance, for example, a detergent. The capsules may contain solid or liquid substances. Blow moulding apparatus suitable for forming such capsules is also disclosed.

1 . An injection moulded capsule comprising solubilizable walls formed from a PVA-containing composition and containing a substance for release upon solubilization of the PVA-containing composition, wherein the PVA composition comprises up to 20% by weight of a plasticizer and up to 5% by weight of a straight or branched chain C 12  to C 24  fatty acid amide as a lubricant.  
     
     
         2 . The capsule according to  claim 1 , wherein the PVA composition comprises partially hydrolyzed PVA having a molecular weight of at least about 10,000.  
     
     
         3 . The capsule according to  claim 1 , wherein the plasticizer comprises glycerol.  
     
     
         4 . The capsule according to  claim 1 , wherein the fatty acid amide comprises a C 16  to C 20  fatty acid amide.  
     
     
         5 . The capsule according to  claim 4 , wherein the fatty acid amide comprises stearamide.  
     
     
         6 . The capsule according to  claim 1 , wherein the PVA composition further comprises a filler.  
     
     
         7 . The capsule according to  claim 1 , wherein the PVA composition further comprises a stearate as external lubricant.  
     
     
         8 . The capsule according to  claim 1 , wherein the capsule is sealed.  
     
     
         9 . The capsule according to  claim 1 , wherein the substance is a detergent powder.  
     
     
         10 . The capsule according to  claim 9 , wherein the capsule has a capacity of at least 10 cm 3 .  
     
     
         11 . The capsule according to  claim 1 , wherein the substance is a detergent liquid.  
     
     
         12 . The capsule according to  claim 10 , wherein the capsule has a capacity of at least 10 cm 3 .  
     
     
         13 . The capsule according to  claim 1 , wherein the substance is a bubble bath composition.  
     
     
         14 . The capsule according to  claim 1 , wherein the substance is a bath oil.  
     
     
         15 . The capsule according to  claim 1 , further comprising a visible seam.  
     
     
         16 . The capsule according to  claim 1 , wherein the substance is consumable.  
     
     
         17 . An apparatus for forming a sealed filled capsule having walls formed from a PVA composition, said apparatus comprising: 
 a supply hopper containing a supply of cold-pressed compounded PVA pellets comprising a PVA composition, wherein the PVA composition comprises up to 20% by weight of a plasticizer, and up to 5% by weight of a straight or branched chain C 12  to C 24  fatty acid amide as a lubricant;    a melt-extruder for melt-extruding the cold-pressed pellets to form PVA feed for blow moulding;    a mould defining a plurality of moulding cavities;    an injector device for injecting a source of PVA composition into each moulding cavity;    an inflator device for inflating the PVA composition in each moulding cavity to form a blow moulded capsule;    a filling device for filling each capsule with a substance, other than a consumable substance such as a pharmaceutical;    a sealing device for sealing each capsule; and    an ejector device for ejecting the filled capsule.    
     
     
         18 . A method for forming a filled capsule, said method comprising: 
 receiving a supply of cold-pressed compounded PVA pellets comprising a PVA composition, wherein the PVA composition comprises up to 20% by weight of a plasticizer, and a straight or branched chain C 12  to C 24  fatty acid amide as a lubricant;    melt extruding the cold-pressed pellets to form PVA feed for blow moulding;    injecting the PVA feed into a mould defining a plurality of cavities;    inflating the PVA within each mould cavity to form a blow-moulded capsule;    filling the capsule with a substance, other than a consumable substance such as a pharmaceutical;    sealing the capsule; and    ejecting the filled capsule.