Integral two layer preform, process and apparatus for the production thereof, process for producing a blow-moulded bag-in-container, and bag-in-container thus produced

Abstract

The invention is an integral two-layer preform for the production of integrally blow-moulded bag-in-containers. The preform has an inner layer and an outer layer, wherein the preform forms a two layer container upon blow-moulding, and wherein the thus obtained inner layer of the container releases from the thus obtained outer layer upon introduction of a gas at a point of interface of the two layers. The melting temperature of the inner layer is greater than or equal to the melting temperature of the outer layer.

1 . An integral two-layer preform for the production of integrally blow-moulded bag-in-containers, said preform comprising:
 an inner layer and an outer layer, wherein said preform forms a two layer container upon blow-moulding, and wherein the thus obtained inner layer of said container releases from the thus obtained outer layer upon introduction of a gas at a point of interface of said two layers; and   the melting temperature of the inner layer is greater or equal to the melting temperature of the outer layer.   
   
   
       2 . The preform according to  claim 1  wherein at least one of the inner and outer layers comprises a semi-crystalline material. 
   
   
       3 . The preform according to  claim 1 , wherein the inner and outer layer consist of different materials. 
   
   
       4 . The preform according to  claim 1 , wherein the inner and outer layer consist of the same material. 
   
   
       5 . The preform according to  claim 1 , wherein the inner and outer layers consist of a material selected from PET, PEN, PTT, PA, PP, PE, HDPE, EVOH, PGAc, PLA, and copolymers or blends thereof. 
   
   
       6 . The preform according to  claim 1 , wherein the at least one point of interface is a vent in the shape of a wedge with the broad side at the level of the opening thereof and getting thinner as it penetrates deeper into the vessel, until the inner and outer layers meet to form an interface. 
   
   
       7 . The preform according to  claim 6 , wherein more than one vent are distributed around the lip of the preform's mouth. 
   
   
       8 . The preform according to  claim 1 , wherein the inner and outer layers of the preform are connected by an interface throughout substantially the whole inner surface of the outer layer. 
   
   
       9 . The preform according to  claim 1  wherein the inner and outer layers and are fixed to one another through mechanical interlocking means located in the preform's neck region. 
   
   
       10 . A process for the production of a preform having
 an inner layer and an outer layer, wherein said preform forms a two layer container upon blow-moulding, and wherein the thus obtained inner layer of said container releases from the thus obtained outer layer upon introduction of a gas at a point of interface of said two layers; and   the melting temperature of the inner layer is greater or equal to the melting temperature of the outer layer, comprising the following sequential steps:   injection moulding the inner layer onto a core;   injection moulding the outer layer onto the inner layer, and   extracting the thus formed preform from the core.   
   
   
       11 . The process according to  claim 10 , wherein said core is adapted for forming vents fluidly connecting the interface between the inner and outer layers to the atmosphere. 
   
   
       12 . A tool of the core shell type suitable for the production of a preform having
 an inner layer and an outer layer, wherein said preform forms a two layer container upon blow-moulding, and wherein the thus obtained inner layer of said container releases from the thus obtained outer layer upon introduction of a gas at a point of interface of said two layers, and   the melting temperature of the inner layer is greater or equal to the melting temperature of the outer layer,   
     comprising a core mould provided at the base thereof with at least one pin suitable for forming a vent at the interface between the first and second layers of said preform. 
   
   
       13 . The tool according to  claim 12  comprising more than one pin disposed around the perimeter of the core base. 
   
   
       14 . The tool according to  claim 12 , wherein the pins have the shape of a wedge. 
   
   
       15 . An apparatus for producing a preform having
 an inner layer and an outer layer, wherein said preform forms a two layer container upon blow-moulding, and wherein the thus obtained inner layer of said container releases from the thus obtained outer layer upon introduction of a gas at a point of interface of said two layers, and   the melting temperature of the inner layer is greater or equal to the melting temperature of the outer layer, comprising:   support means provided with at least two similar male cores;   at least first and second shell female moulds each connected to an extruder, such that the first shell mould is dimensioned for producing the inner layer and the second shell mould for producing the outer layer on top of the inner one;   at least one optional extraction station, and   means for moving the support means so that each core can be positioned sequentially opposite the first shell mould, the second shell mould and, optionally, the extraction station.   
   
   
       16 . The apparatus according to  claim 15 , wherein said means for moving the support impart a linear movement to the support means. 
   
   
       17 . The apparatus according to  claim 15 , wherein said means for moving the support impart a rotational movement to the support means. 
   
   
       18 . Integrally blow-moulded bag-in-container produced by blow-moulding a preform comprising:
 an inner layer and an outer layer, wherein said preform forms a two layer container upon blow-moulding, and wherein the thus obtained inner layer of said container releases from the thus obtained outer layer upon introduction of a gas at a point of interface of said two layers, and   the melting temperature of the inner layer is greater or equal to the melting temperature of the outer layer.