Hollow containers having a very thin inert or impermeable inner surface layer by coating the inside surface of the preform

Abstract

A very thin inner layer composed of a polymer chosen for its barrier and/or inertness properties is fabricated within a container preform constructed mainly from another polymer, or a structure of polymers. The inner layer on the preform is produced either by a controlled coating method involving coating of the injection mold core rod prior to injection molding or by a coating applied directly to the preform after injection molding. This enables both inner and main layers to be brought together at a time when the interface between them is molten. A tie layer can be employed, when desirable, to enable the layers to be combined without melting the layer interface.

1 . A method of fabricating a relatively thin inner layer of a first polymer within a stretch blown container preform consisting of a second polymer, comprising the steps of: 
 (a) heating a molding core rod;    (b) inserting the core rod into a, core rod receiver;    (c) filling a gap formed between the core rod and the core rod receiver with a first polymer while being in a molten state, said first polymer having a predetermined barrier and/or inertness characteristic so as to form a thin barrier layer on said core rod;    (d) removing the core rod from the core rod receiver while the thin barrier layer is still in a molten state;    (e) inserting the core rod and the thin barrier layer into an injection cavity mold;    (f) cooling the core rod; and    (g) feeding a second polymer into the injection mold and flowing said second polymer over the thin barrier layer while still molten, thereby fabricating a preform having a thin inner layer of barrier material.    
     
     
         2 . The method of  claim 1  and additionally including another step between steps (d) and (e) of forming a layer of adhesive on said thin barrier layer.  
     
     
         3 . The method of  claim 2  wherein said another step of providing an adhesive layer comprises inserting the core rod with said thin barrier layer formed thereon into a core rod receiver, containing adhesive material.  
     
     
         4 . A method of fabricating a relatively thin inner layer of a first polymer within a stretch blown container preform consisting of a second polymer, comprising the steps of: 
 (a) cooling a molding core rod;    (b) cooling a core rod receiver;    (c) inserting the core rod into the core rod receiver and forming a gap therebetween;    (d) injecting a first polymer in said gap while being in a molten state and having predetermined barrier and/or inertness characteristic so as to form a thin barrier layer of said first polymer on said core rod;    (e) removing the core rod from the core rod receiver when the first polymer in the gap solidifies, thereby providing an external sleeve of said first polymer on the core rod;    (f) heating the core rod and the external sleeve of said first polymer;    (g) inserting the core rod and the external sleeve into an injection cavity mold; and    (h) feeding a second polymer into the injection cavity mold and flowing the second polymer over the external sleeve of said first polymer to fabricate a preform having a thin inner layer of barrier material.    
     
     
         5 . The method of  claim 4  and additionally including another step between steps (f) and (g) of forming a layer of adhesive on said sleeve.  
     
     
         6 . The method of  claim 5  wherein said another step of providing an adhesive layer comprises inserting the core rod with said thin barrier layer comprising an external sleeve into a core rod receiver containing adhesive material.  
     
     
         7 . A method of fabricating a relatively thin inner layer of a first polymer within a stretch blown container preform consisting of a second polymer, comprising the steps of: 
 (a) cooling a molding core rod;    (b) cooling a core rod receiver;    (c) inserting the core rod into the core rod receiver and forming a gap therebetween;    (d) injecting a first polymer in said gap while being in a molten state and having predetermined barrier and/or inertness characteristic so as to form a thin barrier layer of said first polymer on said core rod;    (e) removing the core rod from the core rod receiver when the first polymer in the gap solidifies thereby, providing an external sleeve of said first polymer on the core rod;    (f) forming a layer of adhesive material on said external sleeve of said first polymer;    (g) inserting the core rod and the external sleeve into an injection cavity mold; and    (h) feeding a second polymer into the injection cavity mold and flowing the second polymer over the external sleeve of the first polymer to fabricate a preform having a thin inner layer of barrier material.    
     
     
         8 . A method of fabricating a relatively thin inner layer of a first polymer within a stretch blown container preform consisting of a second polymer, comprising the steps of: 
 (a) heating a molding core rod;    (b) rotating a coating depositor having a depositing slot therein around the core rod and depositing thereon a thin barrier layer of a first polymer while being in a molten state, said first polymer having predetermined barrier and/or inertness characteristic;    (c) removing the depositor from the proximity of the core rod with the thin barrier layer formed thereon;    (d) inserting the core rod in an injection cavity mold;    (d) cooling the core rod; and    (e) feeding a second polymer into the injection mold and flowing the second polymer over the thin layer of said first polymer while still molten to form a preform having a thin inner layer of barrier material.    
     
     
         9 . The method of  claim 8  and additionally including another step between steps (c) and (d) of forming a layer of adhesive on said barrier layer.  
     
     
         10 . The method of  claim 9  wherein said step of forming a layer of adhesive comprises rotating a depositor containing an adhesive around the barrier layer to form an adhesive layer.  
     
     
         11 . A method of fabricating a relatively thin inner layer of a first polymer within a stretch blown container preform consisting of a second polymer, comprising the steps of: 
 (a) inserting a container preform of said second polymer into a cooling mantle;    (b) inserting a radiant heating element inside of the preform for melting the inner surface of the preform while keeping the main body of the preform relatively cool;    (c) withdrawing the preform from the cooling mantle;    (d) placing a depositor of first polymer adjacent the preform and injecting a predetermined amount of first polymer while in a molten state, and having predetermined barrier and/or inertness characteristics into the preform;    (e) inserting means into the preform for displacing the molten first polymer and evenly spreading the first polymer inside the preform to form an inner layer therein; and    (f) reinserting the preform into the cooling mantle and cooling the spreaded first polymer until it solidifies and forms an inner layer within the preform.    
     
     
         12 . A method as defined by  claim 11  and additionally including the step of heating the means for displacing to enhance the spreading of the first polymer inside the preform following step (e).  
     
     
         13 . The method of  claim 11  and additionally including another step between steps (c) and (d) of forming a layer of adhesive on the inside of said preform.  
     
     
         14 . The method of  claim 11  and additionally including the step of cooling the means for displacing for reducing the thermal stress of said inner layer.  
     
     
         15 . The method of  claim 11  and additionally including another step following step (3) of rotating said means for displacing and evenly spreading the first polymer.  
     
     
         16 . The method of  claim 11  and additionally including a step (g) of inserting heating means in the preform for reheating the inner layer to facilitate a subsequent blow molding of the inner layer.  
     
     
         17 . The method of  claim 11  and additionally including a step (g) of inserting cooling means in the preform for further cooling the inner layer to reduce thermal stress in the inner layer.  
     
     
         18 . A system of fabricating a relatively thin inner layer of a first polymer within a stretch blown container preform consisting of a second polymer, comprising: 
 (a) molding core rod and a core rod receiver;    (b) means for heating the molding core rod and for inserting the core rod into the core rod receiver;    (c) means for filling a gap formed between the core rod and the core rod receiver with a first polymer while being in a molten state, said first polymer having a predetermined barrier and/or inertness characteristic so as to form a thin barrier layer on said core rod;    (d) means for removing the core rod from the core rod receiver while the thin barrier layer is still in a molten state;    (e) an injection cavity mold;    (f) means for inserting the core rod and the thin barrier layer into the injection cavity mold and cooling the core rod; and    (g) means for feeding a second polymer into the injection mold and flowing said second polymer over the thin barrier layer while still molten, thereby fabricating a preform having a thin inner layer of barrier material.    
     
     
         19 . The system of  claim 18  and additionally including means for forming a layer of adhesive on said thin barrier layer prior to flowing said second polymer over the barrier layer.  
     
     
         20 . A system of fabricating a relatively thin inner layer of a first polymer within a stretch blown container preform consisting of a second polymer, comprising: 
 (a) a molding core rod and a core rod receiver;    (b) means for cooling the core rod receiver;    (c) means for inserting the core rod into the core rod receiver and forming a gap therebetween;    (d) means for injecting a first polymer in said gap while being in a molten state and having predetermined barrier and/or inertness characteristic so as to form a thin barrier layer of said first polymer on said core rod and thereafter removing the core rod from the core rod receiver when the first polymer in the gap solidifies, providing thereby an external sleeve of said first polymer on the core rod;    (e) means for heating the core rod and the external sleeve of said first polymer;    (f) an injection cavity mold;    (g) means for inserting the core rod and the external sleeve into the injection cavity mold; and    (h) means for feeding a second polymer into the injection cavity mold and flowing the second polymer over the external sleeve of said first polymer to fabricate a preform having a thin inner layer of barrier material.    
     
     
         21 . The system of  claim 20  and additionally including means for forming a layer of adhesive on said sleeve.  
     
     
         22 . A system of fabricating a relatively thin inner layer of a first polymer within a stretch blown container preform consisting of a second polymer: 
 (a) a molding core rod and a core rod receiver;    (b) means for cooling the molding core rod and the core rod receiver;    (c) means for inserting the core rod into the core rod receiver and forming a gap therebetween;    (d) means for injecting a first polymer in said gap while being in a molten state and having predetermined barrier and/or inertness characteristic so as to form a thin barrier layer of said first polymer on said core rod;    (e) means for removing the core rod from the core rod receiver when the first polymer in the gap solidifies thereby, providing an external sleeve of said first polymer on the core rod;    (f) means for forming a layer of adhesive material on said external sleeve of said first polymer;    (g) an injection cavity mold;    (h) means for inserting the core rod and the external sleeve into the injection cavity mold; and    (i) means for feeding a second polymer into the injection cavity mold and flowing the second polymer over the external sleeve of the first polymer to fabricate a preform having a thin inner layer of barrier material.    
     
     
         23 . A system of fabricating a relatively thin inner layer of a first polymer within a stretch blown container preform consisting of a second polymer: 
 (a) a molding core rod;    (b) means for heating the molding core rod;    (c) a coating depositor having a depositing slot therein locatable around the core rod and including means for depositing a thin barrier layer of a first polymer being in a molten state on said core rod, said first polymer having predetermined barrier and/or inertness characteristic;    (d) means for removing the depositor from the proximity of the core rod after the thin barrier layer is formed thereon;    (e) an injection cavity mold;    (f) means for inserting the core rod in the injection cavity mold;    (g) means for cooling the core rod; and    (h) means for feeding a second polymer into the injection mold and flowing the second polymer over the thin layer of said first polymer while still molten to form a preform having a thin inner layer of barrier material.    
     
     
         24 . The system of  claim 23  and additionally including means for forming a layer of adhesive on said barrier layer.  
     
     
         25 . A system of fabricating a relatively thin inner layer of a first polymer within a stretch blown container preform consisting of a second polymer: 
 (a) a container preform;    (b) a cooling mantle;    (c) means for inserting the container preform of said second polymer into the cooling mantle;    (d) a radiant heating element insertable inside of the preform for melting the inner surface of the preform while keeping the main body of the preform relatively cool;    (e) means for withdrawing the preform from the cooling mantle;    (f) a depositor of a first polymer positionable adjacent the preform for injecting a predetermined amount of said polymer in a molten state into the preform, said first polymer having predetermined barrier and/or inertness characteristics;    (g) means insertable into the preform for displacing the molten first polymer and evenly spreading the first polymer inside the preform to form an inner layer therein; and    (h) means for again inserting the preform into the cooling mantle and cooling the spreaded first polymer until it solidifies, thereby forming an inner barrier layer within the preform.    
     
     
         26 . The system of  claim 25  and additionally including means for heating the displacing means to enhance the spreading of the first polymer inside the preform.  
     
     
         27 . The system of  claim 25  and additionally including means for forming a layer of adhesive on the inside of said preform prior to receiving said first polymer.  
     
     
         28 . The system of  claim 25  and additionally including means for cooling the displacing means for reducing the thermal stress of said inner layer.  
     
     
         29 . The system of  claim 25  and additionally including means for rotating said means for displacing and evenly spreading the first polymer.  
     
     
         30 . The system of  claim 25  and additionally including means for reheating the inner layer within the preform to facilitate a subsequent blow molding of the inner layer.  
     
     
         31 . The system of  claim 25  and additionally including means for further cooling the inner layer in the preform to reduce the thermal stress therein when the inner layer has a lower transition temperature than that of the preform.  
     
     
         32 . A method of fabricating a relatively thin inner barrier layer of a first polymer within a container preform comprising a second polymer, which comprises the steps of: 
 (a) applying a first polymer in a molten state to a molding core rod, said first polymer having a predetermined barrier and/or inertness characteristic, to form a thin barrier layer of said first polymer on said molding core rod;    (b) inserting said core rod and the thin barrier layer into an injection cavity mold;    (c) feeding a second polymer in a molten state into an entry port of the injection cavity mold and flowing said second polymer over the thin barrier layer, said thin barrier layer being in a molten state at its outer-surface which is in contact with said second polymer, thereby fabricating a container preform comprising a thin inner layer of barrier material formed within said second polymer material.