Abstract:
A wrapping material for formed bales of material. The wrapping material including at least one layer of a flexible plastic material film web having a substantially uniform width and divided lengthwise into portions of substantially equal length by a plurality of spaced lines of perforations extending fully transversely across the width of the wrapping material and fully through the layer or layers forming the wrapping material. Each said line of perforations having a first adhesive substrate adhered to a first surface of said wrapping material adjacent to but spaced from the line of perforations. The first adhesive substrate extending substantially across the width of said wrapping material and having, in use, an outwardly facing adhesive surface, and a second adhesive substrate extending substantially across the width of said wrapping material and being adhesively secured to said first surface of the wrapping material whereby the second adhesive substrate overlies said line of perforations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 14/904,605, filed on Jan. 12, 2016, which is a national phase entry under 35 U.S.C. §371 of International Application No. PCT/AU2014/000821, filed on Aug. 20, 2014, published in English, which claims priority from Australian Provisional Application No. 2013903145, filed on Aug. 20, 2013, and which claims priority from Australian Provisional Application No. 2013903304, filed on Aug. 30, 2013, all of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to improvements in wrapping materials and methods of manufacture of same for wrapping of any material formed into bales, including but not limited to, harvested agricultural materials. 
       BACKGROUND TO THE INVENTION 
       [0003]    It is known to form bales of harvested agricultural material, such as hay, silage making materials, cotton and the like, and to wrap same in plastic film web for storage and/or transport. It is also known to form bales of collected rubbish or waste materials and to wrap such bales in a plastic film web. One technique is to secure the formed bale initially with a net material and then to wrap same with plastics film web. A second technique is to wrap the formed bale in multiple overlapping layers of a plastic film web. Typically in such techniques the plastic film web is made from linear low density polyethylene that is made to be self adhesive to adhere to itself. In yet another technique, a single individual length of a plastic film web is used with an applied adhesive strip of sufficient strength to adhere and hold a wrapped bale. Such a technique is described in Australian patent specification nos. 2003292463 and 2005300259 which provide individual and separate lengths of plastic material web formed into a connected roll, each individual length being sufficient to wrap once around a desired bale size. Each individual and separate length is held to an adjacent length by a Z lock fold configuration at its ends and adhesive to form a temporarily continuous roll which in use in a suitable baler is separated from the roll by an applied force of sufficient strength to be then wrapped around and secured to a formed bale. A bale forming machine capable of using this type of wrapping material is disclosed in Australian patent specification no. 2008229852 and US patent specification no. 6263650. 
         [0004]    There is a need to provide an improved wrapping material for wrapping any material formed into a bale, but particularly for harvested agricultural material formed into a bale with substantially one pass of a plastics material film web having a predefined length. There is also a need to provide a method of manufacturing such a wrapping material in a continuous roll whereby each of the predefined lengths of the plastics material film web are formed in a continuous length of adjoining portions that are separable sequentially in a baling machine. 
       OBJECT OF THE INVENTION 
       [0005]    It is an object of the present invention to substantially overcome or at least ameliorate one or more of the disadvantages of the prior art, or to at least provide a useful alternative. 
       SUMMARY OF THE INVENTION 
       [0006]    According to a first aspect, the present invention provides a wrapping material, said wrapping material including at least one layer of a flexible plastic material film web having a substantially uniform width and divided lengthwise into portions of substantially equal length by a plurality of spaced lines of perforations extending fully transversely across the width of the wrapping material and fully through the layer or layers forming the wrapping material, each said line of perforations having a first adhesive substrate adhered to a first surface of said wrapping material adjacent to but spaced from the line of perforations, said first adhesive substrate extending substantially across the width of said wrapping material and having, in use, an outwardly facing adhesive surface, and a second adhesive substrate extending substantially across the width of said wrapping material and being adhesively secured to said first surface of the wrapping material whereby the second adhesive substrate overlies said line of perforations. 
         [0007]    In accordance with a second aspect, the present invention provides a method of manufacturing a roll of wrapping material for wrapping formed bales with an individual portion of said wrapping material, said method including providing a base web of a flexible plastic material film having at least one layer; forming a plurality of substantially evenly spaced lines of perforations extending fully transversely across and fully through said base web; applying a first adhesive substrate to a first surface of said base web adjacent to but spaced from each said line of perforations, said first adhesive substrate having an outwardly facing first adhesive surface covered by a first release liner with a second adhesive surface facing outwardly; applying a second adhesive substrate to said first surface of said base web adjacent to said first adhesive substrate and overlying said line of perforations, said second adhesive substrate having a second release liner covering an outwardly facing adhesive surface of said second adhesive substrate; and rolling said base web into a said roll whereby the second adhesive surface of said first release liner adheres to a second surface of said base web. 
         [0008]    In accordance with yet another aspect of this invention there is provided a wrapping material portion for wrapping a formed bale of material, said wrapping material portion having a base web of a flexible plastic material film having at least one layer, a leading end of said base web having a first adhesive substrate secured to a first surface of the base web and extending substantially across the width of said base web, and a second adhesive substrate adhered to said first surface at a trailing end of said material portion, said second adhesive substrate having an outwardly facing adhesive surface. 
         [0009]    Further preferred features and aspects will become apparent from the following description of preferred embodiments given in relation to the annexed drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a partial schematic perspective view of a base plastic material film web usable in the present invention. 
           [0011]      FIG. 2  is a view similar to  FIG. 1  with adhesive strip materials applied to the base plastic material film web to form a wrapping material in accordance with the present invention; 
           [0012]      FIG. 3  is a view similar to  FIG. 1  showing a further possible form of the base plastic material film web; 
           [0013]      FIG. 4  is a view similar to  FIG. 1  showing a further possible modification to the base plastic material film web in accordance with the present invention; 
           [0014]      FIG. 5  shows a roll of adhesive material strip usable to form the wrapping material of  FIG. 2 ; 
           [0015]      FIG. 6  shows schematically, preferred methods of manufacturing the wrapping material according to the present invention; 
           [0016]      FIG. 7  is a schematic perspective view of one stage in the manufacturing process represented in  FIG. 1 ; 
           [0017]      FIGS. 8 a , 8 b , 8 c  and 8 d    illustrate stages in the rolling up a wrapping material produced according to the method described in relation to  FIG. 6  and in the unrolling of this wrapping material in use in a baling machine; 
           [0018]      FIG. 9  illustrates schematically in edge elevation view, the point at which separation occurs between portions of the wrapping material; 
           [0019]      FIG. 10 a    illustrates a portion of the wrapping material being fed into a baler chamber; and 
           [0020]      FIG. 10 b    illustrates the portion of the wrapping material wrapped about a formed bale. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
       [0021]    Referring to  FIGS. 1 and 2 , the wrapping material  10  may include a base plastic material film web  11  formed by two layers  12 ,  13  adhered to one another. The web  11  has a uniform width with side edges  14 ,  15  and uniformly spaced lines of perforations  16  extending fully across and through the web  11  to define individual length portions  17 ,  18  of equal length along the web  11 . In a roll of the wrapping material, multiple portions  17 ,  18  are provided with the portion  17  being closer to a free end of the roll. The plastic material film of the web  11  may include any thermoplastic membrane which may include master batches and Polyisobutylene (PIB) as an adhesive including linear low density polyethylene or any other polyolefin. Other plastics materials could also be used. The web thickness may be 75 mm made up nominally of two layers of equal thickness (37.5 mm)  FIG. 3  illustrates an alternative base plastic material film web  19  made of a single thickness web but otherwise has the same features as the base web of  FIG. 1 .  FIG. 4  illustrates a further possible arrangement where the lateral edge regions of perforation line  16  are fully severed through the base plastic material film web  11 ,  19  at  28 ,  29  by a short distance (5 to 10 mm) to assist with initiation of separation in use of the wrapping material  10 . Conveniently, the wrapping material is made up into rolls  45  for use in a bale wrapping machine where the individual length portions can be sequentially removed from the roll to be wrapped around a formed bale. A base wrapping material generally according to  FIGS. 1 and 2  can form a roll  45  of at least 24 portions  17 ,  18  although this may vary depending on the thickness of the base wrap material  11 . 
         [0022]      FIG. 2  illustrates the layers of adhesive material strips  20  applied over each zone surrounding the spaced perforation lines  16  along the base plastic material film web  11 ,  19 . The layers  20  comprise a first strip section  21  having a rubber based adhesive (AFT404) substrate  22  covered by a release liner  23  and a tissue based acrylic adhesive layer (AFTDS18)  24 . The rubber based adhesive is of advantage in that it does not stick or adhere to rubber rollers in a baling machine. The first strip section  21  is applied to the base plastic material film web  11 ,  19  such that preferably a short distance is provided between the perforation line  16  and the adjacent edge of the adhesive substrate  22 . The short distance might be of the order of 10-15 mm, preferably 5 to 10 mm. The layers  20  include a second strip section  25  comprised of a tissue based adhesive acrylic based adhesive (AFTDS18) separation layer  26  adhered to the base plastic material film web  11 ,  19  and a covering release liner  27 . Conveniently the second strip section  25  abuts the first strip section  21  such that the tissue based adhesive and separation layer  26  overlies the perforation line  16 . Although the drawings illustrate the tissue based adhesive layer  26  abutting the double sided adhesive tape on a rubber based substrate  22 , it is possible for the layer  26  to overlay the substrate  22 . 
         [0023]      FIG. 5  illustrates a roll  30  of adhesive material strips  20  supported on a release liner layer  31  such that the strips  20  can be formed into a roll ready for application in a wrapping material manufacturing technique as illustrated in  FIGS. 6 and 7 . In one preferred construction, the first strip section  21  may have a width of 200 to 333 mm, preferably about 250 mm. The second strip section  25  may have a width of 75 to 150 mm, preferably about 100 mm, although other dimensions are possible. 
         [0024]    The acrylic based tissue adhesive (AFTDS18) used for layers  26  and  24  has a tear strength that is substantially equal in all directions. The adhesive layer  26 , in overlying the perforation lines  16  increases the strength of the perforation lines from approximately 20 newtons to about 55 newtons such that the web holds together for handling purposes as a continuous web in a baling machine (or similar) until such time as it is desired to remove a web portion from the roll for wrapping about a formed bale. The rubber based adhesive substrate  22  has adhesive effect on both faces and has a tear strength that is greater in the longitudinal direction of the base web material,  19  than on the transverse direction when the substrate  22  is applied to the base web material  11 ,  19 . Moreover, the tear strength in the longitudinal direction is greater than that of the adhesive layer  26 . 
         [0025]      FIG. 6  illustrates schematically some possible methods of manufacturing a wrapping material  10  in accordance with the present invention. As illustrated, the manufacturing apparatus  32  may include a bubble film production machine  33  including a resin extruder  34 , a raw material feed hopper  35  and a die and air ring  36  for forming an air inflated film bubble or tube  37  of conventional form. The film bubble may be a mono layer plastics material or a multi layered co-extruded structure including two, three or more layers coextruded structures. In the latter case, the inner surface of the plastics material film bubble may contain PIB (polyisobutylene) to aid with the adherence of the layers together when flattened. The film bubble  37  is passed through nip rollers  38  to press the film together forming a flattened film of two adhered layers  39  with a normal width slightly greater than that of the required wrapping material. The two adhered layers  39  also having a nominal thickness equivalent to the thickness of the desired wrapping material. Of course, if the extruder produces multiple layers then each of the two layers will have further internally different layer structures. The layers  39  are then passed to a perforating machine  40  to form a full width line of perforations  16  ( FIGS. 1 to 5 ) fully across the width of the layers  39  and fully through the layers  39 . Rather than using blown film, it is also possible to use cast film and laminated cast film if desired. The perforation lines  16  are formed at evenly spaced intervals whereby the length of the material layers  39  between the perforation lines is equivalent to one wrap material length for a desired bale size. The wrap material base layers  39  ( FIGS. 1, 4 ) might then be formed into rolls for subsequent processing as illustrated, or continued processing in line could occur as described hereafter. The apparatus  32  might include an optional labelling devices  41 , such as an RFID labeller, for applying indicative labels (as desired) to the base layers of the wrap material  39 . If used, the labelling device  41  might be provided at any stage in the production process, post formation of the perforation lines  16 . Moreover in an automatic baling machine, the film web exiting the roll  45  will be braked by any suitable means whereby continued movement of the foremost portion  17  will cause sufficient separation forces on the perforation line  16  to initiate separation of the portion  17  from the remainder of the connected portions on the roll  45 . The labelling device  41  may then apply an indicative marker or label to the base web material to initiate braking of the web material in a baling machine. 
         [0026]    The apparatus  32  may further include a tape application station  42  for applying an adhesive tape strip  20  to the region of each perforation line  16  ( FIG. 7 ). In this embodiment, the backing release line  31  is removed from the strips  20  and the adhesive strips are laid fully across the surface  46  (in use) of the web  39  with the second strip section  25  overlying the perforation line  16 . The strips  20  are separated from the roll  30  adjacent the near edge of the base material film web  39  and thereafter an edge trimming device  43  trims the edges  14 ,  15  of the base material web  39  including, if needed, ends of the strips  20  such that the then formed wrapping material  10  has the required width. The wrapping material  10  then passes over a driven lay-on roller  44  to be rolled up as a roll  45  ready for use in a baler. 
         [0027]      FIGS. 8 a  and 8 b    illustrate the adhesive strips  20  applied to the web surface  46  as the roll  45  is formed such that the adhesive strips  20  are sandwiched between two portions of the base material film web with adhesive layers  22 ,  26  adhered to the web surface  46  and the adhesive layer  24  adhered to an opposed surface  47  of the base material film web  39 .  FIGS. 8 c  and 8 d    illustrate schematically, the adhesive strips  20  as the roll  45  is rolled out in use in a baler. As shown in  FIG. 8 c   , the release liner  23  and adhesive layer  24  detach from the substrate adhesive layer  22  and remain adhered to the other surface  47  of the base film web material  39 . The remainder of the strips  20 , namely the substrate adhesive layer  22  and the adhesive layer  26  and release liner  27  remain adhered to the outer surface  46  of the base film web material  39 . The adhesive substrate layer  22  is adhered adjacent to a perforation line  16  at a trailing end of a forward portion length  17  of the base film web material  39  with the adhesive strip  26  and release liner  27  adhered to a leading end of a following portion length  18  of the base film web material  39 . 
         [0028]    As shown in  FIG. 9 , the lead or forward portion is, in use, carried forward by the baler with the following portion length  18  braked with the remainder of the roll  45 . At a predetermined force loading, the portions separate at the perforation line  16 . Separation initiates on the highest elongation point on the outermost edges  14 ,  15  of the base film web  11 ,  19  where it incrementally creates a separation angle great enough to initiate the activation of the perforations of line  16  at the required angle as opposed to a straight linear direction break. At the point of separation the tissue based adhesive layer  26  has a stronger bond to the film layer than the release liner and transfers across to provide an adhesive strip  73  to cover the gap between the edge of the perforation point and the nominal distance to the rubber based substrate adhesive layer  22  set back from the perforation line  16 . The perforation once activated by the separation of the adhesive tissue layer  26 , creates a secondary process which allows the tape to tear along the perforation separation point creating a substantially clean edge  16 ′ with fine film tails created by normal mechanical working of a perforation. 
         [0029]    As shown in  FIGS. 10 a , 10 b    the separated film portion  17  is fed into the baler chamber with the adhesive layer  26  and release layer  27  on the lead edge stiffening and assisting feeding of the web into the chamber about a bale  70 . The film portion  17  passes around a roller  71  along a feed path  72  and around the bale  70  with the trailing edge zone carrying the rubber based adhesive substrate  22  being pressed to the lead edge zone to complete the wrapping process ( FIG. 10 b   ). The adhesive strip  73  and the adhesive substrate  22  ensures that the tail end of the film web portion  17  has no regions likely to lift and break the seal of the wrapping.