Double wall bags

Abstract

The invention relates to plastic bags and sack for use especially in the food and pharmaceutical industries. The bag ( 2 ) comprises inner and outer bag sections ( 4, 14 ) which are joined at least at an upper portion in a manner which allows them to be separated when required, such as by heat sealing. The outer bag section ( 14 ) may be provided with a mouth ( 10 ) through which the inner bag section can be withdrawn when required. Alternatively, the outer bag section may be peeled away from the inner bag section. The inner bag section is heat sealed after filling with contents to retain the contents in the inner portion. The heat sealing step also serves to secure the bag sections together as above. The inner bag section is preferably provided with a closeable mouth ( 132 ) separate from the end by which it is filled, through which the contents may be dispensed.

1 . A plastic bag comprising: 
 i) a cover section comprising first and second opposed walls;    ii) a bag section comprising third and fourth opposed walls joined at their side and base edges and an open end by means of which the bag section may be filled with contents, the first and second walls being arranged to enclose the bag section;    iii) a closeable mouth defined in a wall of the bag section for access in use to the interior of the bag section;    iv) a closeable region, distinct from the mouth, including an end portion of the cover section and an end portion of the bag section proximate the open end of the bag section, within which closeable region the bag section may be sealed closed after filling;    wherein, in the closeable region, an internal face of at least one of the respective first and second walls is attached and/or attachable to an adjacent external face of a wall of the bag section, the attachment being such that the bag section is separable in use from the cover section without compromising the seal of the bag section in the closeable region.    
   
   
       2 . A plastic bag as claimed in  claim 1  wherein the open end of the bag section may operatively be sealed after filling by heat sealing the bag section walls together in the closeable region.  
   
   
       3 . A plastic bag as claimed in  claim 1  wherein, for attachment of the cover section to the bag section in said closeable region, an internal face of at least one of the respective first and second walls of the cover section is attachable to at least one external face of a bag section wall by heat sealing in the closeable region.  
   
   
       4 . A plastic bag as claimed in  claim 3  wherein at least one member selected from the group comprising the internal faces of the first and second walls and the respective external faces of the bag section walls comprises a first treated area in the closeable region, said first treated area being effective to limit the strength of the heat seal between the cover section and bag section.  
   
   
       5 . A plastic bag as claimed in  claim 4  wherein said first treated area comprises printed areas, the printed areas being resistant to heat sealing.  
   
   
       6 . A plastic bag as claimed in  claim 1  wherein the first and second walls are also separably attached respectively to the bag section walls in areas other than said closeable region.  
   
   
       7 . A plastic bag as claimed in  claim 6  wherein the first and second walls are removeably heat sealed respectively to the bag section walls in said separably attached areas.  
   
   
       8 . A plastic bag as claimed in  claim 1  wherein at least one of the first wall and the adjacent bag section wall and/or at least one of the second wall and the adjacent bag section wall comprises a second treated area, said second treated area being effective to limit the strength of the heat seal between respectively the first and third and the second and fourth walls in said separably attached areas.  
   
   
       9 . A plastic bag as claimed in  claim 8  wherein said second treated area comprises printed areas, the printed areas being resistant to heat sealing.  
   
   
       10 . A plastic bag as claimed in  claim 3 , wherein said first treated area extends across the whole inner surface of the first and/or second wall.  
   
   
       11 . A plastic bag as claimed in  claim 10  wherein the first and second walls are also separably attached respectively to the bag section walls in areas other than said closeable region.  
   
   
       12 . A plastic bag as claimed in  claim 11  wherein the first and second walls are removeably heat sealed respectively to the bag section walls in said separably attached areas.  
   
   
       13 . A plastic bag as claimed in  claim 5  comprising, in a said treated area, alternate printed and non-printed areas.  
   
   
       14 . A plastic bag as claimed in  claim 13  wherein the area of the printed areas is greater than the area of the non-printed areas.  
   
   
       15 . A plastic bag as claimed in  claim 13  wherein the printed and non-printed areas alternate to define stripes across the closeable region and/or across the separably attached areas.  
   
   
       16 . A plastic bag as claimed in  claim 13  wherein the non-printed areas have a width of not more than about 2 mm.  
   
   
       17 . A plastic bag as claimed in  claim 13  wherein the printed areas have a width of not more than about 10 mm.  
   
   
       18 . A plastic bag as claimed in  claim 4  wherein the treated area comprises an embossed area of one or more of the walls.  
   
   
       19 . A plastic bag as claimed in  claim 1  wherein the cover section is longer than the bag section such that the cover section extends beyond the base end of the bag section, the first and second walls being joined to each other in said lengthwise extending portion.  
   
   
       20 . A plastic bag as claimed in  claim 1  wherein the width of the cover section is greater than the width of the bag section such that the cover section extends beyond the side edges of the bag section, the first and second walls being joined to each other in said widthwise extending portion.  
   
   
       21 . A plastic bag as claimed in  claim 6  wherein the width of the cover section is greater than the width of the bag section such that the cover section extends beyond the side edges of the bag section, the first and second walls being joined to each other in said widthwise extending portion.  
   
   
       22 . A plastic bag as claimed in  claim 1  further comprising: 
 a first closure flap overlying and closing said mouth defined in a wall of said bag section said first closure flap including a first attached region which is peelably attached to said bag section wall such that at least a portion of said first closure flap may be peeled away from said bag section wall across the peelably attached region to reveal the mouth, and, optionally, a second attached region spaced from the peelably attached region in which second region said first closure flap is also attached to said bag section wall.    
   
   
       23 . A plastic bag as claimed in  claim 1  comprising: 
 a first closure flap overlying and closing said mouth defined in a wall of said bag section said first closure flap including a first region which is attached to a said bag section wall, said first closure flap including at least one line of weakness defining a tearable portion of said first closure flap within which tearable portion said first closure flap is not attached to the bag section wall and which tearable portion can be opened by tearing along the line of weakness to reveal the mouth; and, optionally, a second attached region spaced from the tearable portion in which second region said first closure flap is also attached to said bag section wall.    
   
   
       24 . A plastic bag as claimed in  claim 22  wherein the first closure flap extends into the closeable region.  
   
   
       25 . A bag as claimed in  claim 24  further comprising a closure flap; 
 wherein, for attachment of the cover section to the bag section in said closeable region, an internal face of at least one of the respective first and second walls of the cover section is attachable to at least one external face of a bag section wall by heat sealing in the closeable region;    wherein at least one member selected from the group comprising the internal faces of the first and second walls and the respective external faces of the bag section walls comprises a first treated area in the closeable region, said first treated area being effective to limit the strength of the heat seal between the cover section and bag section;    wherein the first closure flap is overlying and closing said mouth defined in a wall of said bat section said first closure flap including a first attached region which is peelably attached to said bag section wall such that at least a portion of said first closure flap may be peeled away from said bag section wall across the peelably attached region to reveal the mouth, and, optionally, a second attached region spaced from the peelably attached region in which second region said first closure flap is also attached to said bag section wall; and    wherein a first treated area is formed on the first closure flap instead of a treated area of the bag section.    
   
   
       26 . A plastic bag according to  claim 1  wherein on or both of the respective first and second walls of the cover section is/are adhered to the bag section proximate the open end of the bag section.  
   
   
       27 . A plastic bag as claimed in  claim 26  wherein the cover section is adhered to the bag section at marginal portions of the closeable region.  
   
   
       28 . A plastic bag as claimed in  claim 1  further comprising a second closeable mouth defined in the first or second wall of the cover section for access in use to the bag section.  
   
   
       29 . A plastic bag as claimed in  claim 1  further comprising: 
 a second closure flap including a first region which is peelably attached to said cover section wall such that at least a portion of the closure flap may be peeled away from said cover section wall across the peelably attached region and a second attached region spaced from the peelably attached region in which second region the second closure flap is also attached to said cover section wall.    
   
   
       30 . A plastic bag as claimed in  claim 1  further comprising: 
 a second closure flap including a first region which is attached to said cover section wall, the second closure flap including at least one line of weakness defining a tearable portion of the closure flap within which tearable portion the closure flap is not attached to said cover section wall and which tearable portion can be opened by tearing along the line of weakness and a second attached region spaced from the tearable portion in which second region the second closure flap is also attached to said cover section wall.    
   
   
       31 . A plastic bag as claimed in  claim 29  wherein the second closure flap is arranged to cover the second mouth.  
   
   
       32 . A plastic bag as claimed in  claim 1  further comprising gripping means formed in or on, or attached to the first or second walls, to facilitate gripping of said walls on separation of the cover section from the bag section.  
   
   
       33 . A method of handling a flowable product comprising: 
 i) providing a bag as claimed in  claim 1;     ii) filling the bag section with the flowable product through the open end of the bag; and    iii) applying heat sealing means to the closeable region thereby to heat seal the bag section walls together to sealingly close the bag section and to heat seal the first and/or second walls to the bag section walls to separably attach cover section and bag section together.    
   
   
       34 . A method as claimed in  claim 33  further comprising: 
 iv) separating the cover section from the bag section in the closeable region;    v) if necessary, separating the cover section from the bag section outside the closeable region and    vi) withdrawing the bag section from the cover section.    
   
   
       35 . A plastic bag comprising: 
 i) a cover section comprising first and second opposed walls;    ii) a product containing bag section comprising third and fourth opposed walls joined at their side and base edges, the first and second walls being arranged to enclose the bag section;    iii) a closeable mouth defined in a wall of the bag section for access in use to the interior of the bag section;    iv) a sealing region, distinct from the mouth, including an end portion of the cover section and an end portion of the bag section within which sealing region the bag section is sealed closed after filling bag section with product;    wherein, in the sealing region, an internal face of at least one of the respective first and second walls is attached to an adjacent external face of a wall of the bag section, the attachment being such that the bag section is separable in use from the cover section without compromising the seal of the bag section in the sealing region.    
   
   
       36 . A plastic bag as claimed in  claim 35  wherein, within the sealing region the respective first and second walls of the cover section are attached to at least one of the external faces of the respective bag section walls of the bag section by means of a heat seal formed contemporaneously with the heat seal which seals the bag section walls.  
   
   
       37 . A plastic bag as claimed in  claim 36  wherein at least one of the internal faces of the first and second walls and the external faces of the bag section walls comprises a treated area in the sealing region, the treated area being effective to limit the strength of the heat seal between the cover section and bag section.  
   
   
       38 . A plastic bag as claimed in  claim 35  further comprising: 
 a first closure flap overlying and closing said mouth defined in a wall of said bag section said first closure flap including a first attached region which is peelably attached to said bag section wall such that at least a portion of said first closure flap may be peeled away from said bag section wall across the peelably attached region to reveal the mouth, and, optionally, a second attached region spaced from the peelably attached region in which second region said first closure flap is also attached to said bag section wall.    
   
   
       39 . A plastic bag as claimed in  claim 35  comprising: 
 a first closure flap overlying and closing said mouth defined in a wall of said bag section said first closure flap including a first region which is attached to a said bag section wall, said first closure flap including at least one line of weakness defining a tearable portion of said first closure flap within which tearable portion said first closure flap is not attached to the bag section wall and which tearable portion can be opened by tearing along the line of weakness to reveal the mouth; and, optionally, a second attached region spaced from the tearable portion in which second region said first closure flap is also attached to said bag section wall.    
   
   
       40 . A plastic bag as claimed in  claim 38  wherein the first closure flap extends into the closeable region.  
   
   
       41 . A bag as claimed in  claim 40   wherein at least one of the internal faces of the first and second walls and the external faces of the bag section walls comprises a treated area in the sealing region, the treated area being effective to limit the strength of the heat seal between the cover section and bag section; and    further comprising:    a first closure flap overlying and closing said mouth defined in a wall of said bag section said first closure flap including a first attached region which is peelably attached to said bag section wall such that at least a portion of said first closure flap may be peeled away from said bag section wall across the peelably attached region to reveal the mouth, and, optionally, a second attached region spaced from the peelably attached region in which second region said first closure flap is also attached to said bag section wall;    wherein a first treated area is formed on the first closure flap instead of a treated area of the bag section.    
   
   
       42 . (canceled)