Abstract:
Packaging insulation for insertion into a packaging container, which includes an air laid natural fibrous batt comprised primarily of natural fibers, having foldable paper sheet material adhered to both sides of the batt. The resulting method and product provides packaging insulation which can be shipped flat and compressed, which expands when unpacked and which can be readily folded to match the interior configuration of a shipping container, such as a cardboard box.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to the field of packaging insulation. 
       PRIOR ART 
       [0002]    Packaging insulation is used for shipping perishable items which must be kept cold during shipping. Individualized packages in which such items are shipped are lined with insulation to maintain the shipped item or items at the appropriate temperature. Current packaging insulation products comprise semi rigid expanded styrene panels, polymer bags stuffed with cotton, or Kraft paper bags stuffed with cotton. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention comprises packaging insulation for insertion into a packaging container, which includes an air laid natural fibrous batt comprised primarily of natural fibers, having foldable paper sheet material adhered to both sides of the batt. The resulting method and product provides packaging insulation which can be shipped flat and compressed, which expands when unpacked and which can be readily folded to match the interior configuration of a shipping container, such as a cardboard box. 
         [0004]    These and other features, advantages and objects of the invention will be more readily understood and appreciated by reference to the drawings, description of the preferred embodiments, and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a perspective view of a preferred embodiment packaging insulation; 
           [0006]      FIG. 2  is a perspective view of two pieces of packaging insulation cut to fit within a particular shipping container; 
           [0007]      FIG. 3  is a perspective view of a cardboard shipping container without packaging insulation; 
           [0008]      FIG. 4  is a perspective view of the container of  FIG. 3  lined with the packaging insulation pieces of  FIG. 2 ; 
           [0009]      FIG. 5  is a plan view of the compression equipment used to form the packaging insulation of the preferred embodiment; and 
           [0010]      FIG. 6  is a top plan view of the compression equipment. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0011]    In the preferred embodiment laminated packaging insulation  1  comprises an air laid natural fiber batt  10 , laminated between two layers of paper sheet material  20  ( FIG. 1 ).  FIG. 2  shows a sheet of the packaging insulation  1  which has been cut into pieces  1   a  and  1   b  to fit within the cardboard shipping container  30  of  FIG. 3 . Packaging insulation  1  is readily foldable into appropriate shipping container configurations. As shown in  FIG. 4 , piece  1   b  has been folded to cover the bottom, one side and the lid of container  30 . Piece  1   a  has been folded to cover the remaining three sides of container  30 . 
         [0012]    The air laid natural fiber batt  10  is formed of natural fibers, preferably cotton fibers, and most preferably recycled cotton fibers. The lengths of the fibers are irregular, but substantially fall between about 1 to about 30 mm. The denier of the recycled cotton fibers is similarly irregular, but substantially falls between about 1 to about 30. From about 5 to about 30% thermoplastic binder fiber, more preferably about 10-25%, and most preferably about 15-20%, is mixed in with the natural fibers. Binder fibers typically comprise a higher melting point thermoplastic core fiber, encased in a lower melting point thermoplastic sheath. 
         [0013]    The paper sheet material used preferably Kraft paper at a thickness of about 1 to about 10 mils, more preferably about 2 to about 6 mils, and most preferably about 4 mils. From about 20 to about 60# Kraft Paper, more preferably about 30# to about 40#, and most preferably about  35 #, is preferred. The presence of the binder fibers in batt  10  may be sufficient to adhere the Kraft paper  20  to batt  10  during the heating, compression and cooling process described below. However, the Kraft paper is preferably coated with a low density polyethylene (LDPE) or high density polyethylene coating (HDPE), which becomes tacky and adhering on heating. The paper may have an HDPE or LDPE coating on both sides, to enhance its impermeability to moisture. 
         [0014]    The natural fibers are normally shipped in bales, which are “opened” using a bale opening machine and process, which separates the fibers. They are mixed with the binder fibers and delivered by the flow of air into an air lay machine that forms a continuous batt and delivers it to a continuously moving conveyor belt. The fibers will be air laid to a thickness which is appropriate to the final thickness desired. The fibers will be air laid to a thickness which is greater than, but appropriate to the final thickness desired. A batt as air laid on the conveyor may vary widely, but from about 3 to about 6 inch thicknesses are typical. The batt is conveyed through an oven at a temperature of about 175° C. to about 195° C., typically about 180 to 185° C. The heat of the oven tackifies the sheath of the binder fibers to assist in binding the natural and binder fibers together and give the batt cohesion. 
         [0015]    From the oven, the batt is conveyed along to compressor  50  ( FIGS. 5 and 6 ). Compressor  50  comprises a series of upper and lower compression rollers  51   a - b ,  53   a - b ,  55   a - b ,  57   a - b  and  59   a - b  which respectively carry a conveyor belt  50   a  and  50   b,  made of a low friction material such as Teflon. Located between the compression rollers, are compression plates  52   a - b ,  54   a - b ,  56   a - b  and  58   a - b , which press against the upper and lower Teflon conveyor belts  50   a  and  50   b . The Teflon conveyor belts  50   a  and  50   b  slide over and past the compression plates. 
         [0016]    As fibrous batt  10  is fed between the upper and lower Teflon conveyor belts  50   a  and  50   b , at upper and lower starter rolls  51   a  and  51   b , the PET film facing stock is fed from one of the upper rolls  40   a  under the upper Teflon conveyor belt  50   a  at top roll  51   a  and from one of the lower rolls  40   b  over the lower Teflon conveyor belt  50   b  at bottom roll  51   b  so as to be applied to both opposite sides of the passing fibrous batt  10  ( FIG. 5 ). Two separate top feed stock rolls  40   a  can carry the same full width paper rolls and used in the alternative, or can carry paper rolls of two different widths and used in the alternative, or can carry two narrower paper rolls and used simultaneously to feed two side by side rolls of paper, which overlap slightly during the lamination process. The same is true for the two separate bottom feed stock rolls  40   b.    
         [0017]    The batt continues to pass between the upper and lower Teflon conveyor belts, carried by alternating upper and lower compression rollers and compression plates, which gradually reduce the thickness of the laminated batt to the target thickness. Compression rolls  51   a - b , and  53   a - b  are heated to from about 170° C. to about 190° C., while rolls  55   a - b ,  57   a - b  and  59   a - b  are cooled to about 40° F. to about 55° F. Similarly, compression plates  52   a - b  and  54   a - b  are heated to from about 170° C. to about 190° C., while plates  56   a - b  and  58   a - b  are cooled to about 40° F. to about 55° F. In this manner, binding fibers in the fibrous batt continue to be adhering and tacky, and the LDPE on the paper stock becomes heated and tacky, through the heated compression rollers and heated compression plates. When the batt reaches the cooling rollers and cooling compression plates, the heated and tacky binder fabrics and the LDPE on the paper stock begin to solidify and complete the adherence process, both between fibers in the batt, and between the batt and the paper laminated to each opposing face of the bait. 
         [0018]    As the laminated batt passes the final compression rolls  59   a  and  59   b,  it passes through longitudinal cutters  60  adjustably mounted on a support  61 . This cuts the batt to desired widths. The batt so cut then passes a guillotine cutter blade  70  which cross-cuts the batt to desired lengths, 
         [0019]    The resulting packaging insulation products  1  are cut to desired dimensions for specific packaging insulation requirements, and are from about ¼ to about 3 inches thick, and have a density of from about one to about seven pounds per cubic foot. The packaging insulation products can be shipped flat and compressed for economy of shipment. When they are unpacked at the customer&#39;s location, they expand back to at least near their original thickness, and can be folded to fit the packaging container in which product is to be shipped. Preferably, two panels are provided for each package ( FIG. 2 ), one of which can be folded to cover the bottom, rear side and top of the container, and the other of which can be folded to cover the two ends and front side of the container ( FIGS. 3 and 4 ). 
         [0020]    Of course it is understood that the above are preferred embodiments of the invention, and that various changes and alterations can be made without departing from the spirit and scope of the invention, as set forth in the appended claims.