Abstract:
A plastic package uses a substrate and an overlay, where both the substrate and the overlay are of materials which can be recycled together, for example polyethylene terephthalate (PET). The plastic used for the overlay may be different from the plastic used for the substrate, provided that the plastics are of the same thermoplastic family, or are of types which are compatible for recycling together. A method of making the package includes the steps of: positioning the product on a vacuum-forming fixture; heating a first layer of thermoplastic, positioning it over the product, and applying a vacuum to the fixture to pull the first layer of thermoplastic onto the product; and thermally bonding the first layer and a second layer of recycling-compatible thermoplastic to each other with the product between them, so as to capture the product. Apparatus having lease two stations is provided to carry out the method and thereby produce the package.

Description:
REFERENCE TO RELATED APPLICATION 
       [0001]    This is a formal application based on and claiming the benefit of provisional application Ser. No. 61/587,789 filed Jan. 18, 2012. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates generally to plastic packaging, and more specifically to plastic packaging where an article is trapped between two layers of plastic, typically for retail sales of the article, but potentially for any other application where it is desirable to package or encapsulate an article. 
         [0004]    A common application for the invention, for example, is packaging drill bits or other power tool accessories for eventual retail sale. However, the invention could be used for a wide variety of packaging needs, with few or no limitations as to the field of use. 
         [0005]    2. Description of the Prior Art 
         [0006]    Packaging using plastic is now ubiquitous. A particularly common form of packaging, especially for relatively small articles, is so-called “skin card” packaging, where the product is sandwiched between a printed cardboard substrate and a thermoplastic overlay (typically polyethylene). A heated plate is used to bond the plastic overlay to the substrate, except in the area of the product. 
         [0007]    Another common form of packaging is so-called “sliding blister” packaging, where a relatively stiff plastic overlay (0.25 mm -0.54 mm polyvinyl chloride (PVC) or polypropylene (PP) for example), having a cavity for the product and folded-over edges on three sides, receives a printed cardboard backing which slides in via the side which is not folded over. 
         [0008]    Yet another common form is so-called “double blister” packaging, where a printed cardboard backing is sandwiched between two layers of plastic (PVC for example), one or both layers of the plastic having cavities to accommodate the product. In some cases, the plastic layers are bonded to each other, typically by heat, while in other cases they may be hinged to each other along one edge, and snapped or bonded together. 
         [0009]    Although such packaging is effective and relatively inexpensive, it suffers from a significant drawback of increasing importance, namely that the substrate and the overlay are typically of different materials. For example, the substrate may be cardboard, and the overlay may be a thermoplastic polymer such as PVC or some other thermoplastic. As recycling becomes more and more important, and in some jurisdictions mandatory, this makes such packaging increasingly unacceptable or uneconomical, due to the difficulty of separating the overlay from the substrate, for example the plastic from the cardboard. Increasingly, countries are requiring or will be requiring that packaging be readily recyclable. Such packaging is recyclable, but not without effort and expense. 
         [0010]    Many plastic packages have security tags. Some are just attached to the packages, and can be easily removed. It is desirable to have a security tag which cannot be removed. 
       SUMMARY OF THE INVENTION 
       [0011]    In view of the above, it is an object of this invention to provide plastic packaging which may be readily recycled without a materials separation problem. Thus in a preferred embodiment, a package is provided in which a product is captured between a substrate and an overlay, with only one plastic material used for both the substrate and the overlay, and no cardboard or other material. 
         [0012]    In one embodiment of the invention, for example, both the substrate and the overlay may be of polyethylene terephthalate (PET). In other exemplary embodiments, plastics other than PET may be used, but the same plastic is used for both the substrate and the overlay. 
         [0013]    In another embodiment, the plastic used for the overlay may be different from the plastic used for the substrate, provided that the plastics are of the same thermoplastic family, or are of types which are compatible for recycling together. 
         [0014]    In a preferred embodiment, the plastic packaging has a security tag which preferably cannot be seen and which cannot be removed from the packaging without visible damage to the packaging. Preferably, the security tag is also made of plastic and can be recycled together with the packaging. The security tag may be provided between the substrate and the overlay or another overlay, and may be a Sensormatic (trademark) tag or the like, for example. 
         [0015]    The invention provides a method of packaging a product, which may include the steps of: positioning the product on a vacuum-forming fixture; heating a first layer of thermoplastic, positioning it over the product, and applying a vacuum to the fixture to pull the first layer of thermoplastic onto the product; and thermally bonding the first layer and a second layer of recycling-compatible thermoplastic to each other with the product between them, so as to capture the product. 
         [0016]    The invention also provides apparatus for carrying out the method, having a first station adapted for positioning the product on a vacuum-forming fixture, for heating a first layer of thermoplastic and positioning it over the product, and for applying a vacuum to the fixture to pull the first layer of thermoplastic onto the product; and a second station adapted for thermally bonding the first layer and a second layer of recycling-compatible thermoplastic to each other with the product between them, so as to capture the product. 
         [0017]    Further details of the invention will be described or will become apparent in the course of the following detailed description and drawings of specific embodiments of the invention, as examples. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Embodiments of the invention will now be described, by way of example only, with reference to the attached drawings, in which: 
           [0019]      FIG. 1  is front perspective view of an example of a finished package according to the invention; 
           [0020]      FIG. 2  is a rear perspective view of the package of  FIG. 1 ; 
           [0021]      FIG. 3  is a exploded perspective view of the package; 
           [0022]      FIG. 4  is a perspective view of a plate with products in the first step of positioning the product on a fixture; 
           [0023]      FIG. 5  shows the step of applying an overlay layer to capture the products; 
           [0024]      FIG. 6  shows an overlay sheet positioned with the products captured beneath it, i.e. between it and the substrate; 
           [0025]      FIG. 7  shows the step of bonding a security tag and a label to the substrate; 
           [0026]      FIG. 8  shows the step of bonding the substrate with the security tag, to the overlay layer; 
           [0027]      FIGS. 9A to 9F  illustrate an example of the apparatus, and the method; 
           [0028]      FIG. 10  is a perspective view of an example of a heat-sealing apparatus for the second step of the method; and 
           [0029]      FIG. 11  is a second perspective view of the heat-sealing apparatus. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Package 
       [0030]    An example of a package according to the invention is shown in  FIGS. 1-3 . The package includes a product  3  (a tile bit in this case, as an example only) on an opaque plastic substrate  4 . The product  3  is captured against the substrate  4  by a transparent plastic overlay  2 . Both the substrate  4  and the overlay  2  in this example are of polyethylene terephthalate (PET). The substrate is 0.43 mm thick PET, starting as white and then printed on both sides (in one example color on the front, and black and white on the back, though that obviously could vary). The overlay  2  is 0.22-0.25 mm clear PET. The overlay  2  is heat-bonded to the substrate  4  using a high-frequency welding machine, at least around the edges of each package, and potentially elsewhere if/as desired. 
         [0031]    The overlay  2  holds the product in perfect position, and the overlay  2  and the substrate  4  are bonded to each other so as to capture the product between them. 
         [0032]    For security purposes, at the back of the substrate  4 , a security tag  5  can be captured against the substrate  4  by a plastic cover  6 . The plastic cover  6  is also heat bonded to the substrate  4  using high-frequency welding machine, at least around the edges of the plastic cover, and potentially elsewhere if/as desired. In this way, the security tag  5  is sealed and hidden in the package. It can not be removed without breaking the package. The plastic cover  6  can be a UPC label substrate. It could also be made of thermoplastic. 
         [0033]    If the product to be packaged has a flat shape, like a blade for example, a plastic front  7  including a pocket  8  for receiving the blade can be provided. The pocket can have projections for engaging the blade to keep the blade from moving once inside the package. A portion of the substrate  4  is not adhered to the plastic front  7  to provide an easy opening access between the plastic front  7  and the substrate  4 . 
         [0034]    For some products with a flat profile, like a saw for example, a peg or pegs (not shown) can also be provided in the plastic front that engages a portion of the blade to ensure that the blade is properly oriented in the package during the packaging process. 
         [0035]    A hang slot  10  is provided in the package, so that the packaged product can be hung on a display peg at a retail outlet. 
       Packaging Process 
       [0036]    An example of the packaging process for producing the plastic package is also provided. The packing process includes: step  1 , positioning the product on a holding fixture; step  2 , heating a first layer of thermoplastic and positioning it over the product, and applying a vacuum to the fixture to pull the first layer of thermoplastic onto the product; and step  3 , thermally bonding the first layer and a second layer of recycling-compatible thermoplastic to each other with the product between them, so as to capture the product.  FIGS. 9A-9F  illustrate the process and of the apparatus. 
         [0037]    In the prototype manufacturing system, some of the steps are carried out manually or semi-manually, but it should be appreciated that the entire process could be automated. 
         [0038]    Step  1 , position product on a holding fixture (a plate, for example).  FIG. 4  shows the plate loaded with products. Many products  3  are evenly positioned on one holding fixture  21  such as an aluminum plate. On the plate, there are many recesses  22  and raised supports  23  for positioning and holding the products on the plate. For each product, one recess  22  and a raised support  23  just in front of the recess  22  are supplied to aid in positioning and to hold the product in position. The recess  22  and the raised support  23  may be made of magnetic material to help secure ferrous products to the fixture. The recesses  22  should be no deeper than necessary to keep the products in position; the products  3  preferably should still project above the surface of the plate, though for light-weight products or products with a large surface area, that may not be essential. 
         [0039]    As shown in  FIG. 4 , three elongated sticks  25  with rectangular cross section are provided in the middle of the plate  21  and both sides of the plate to help in applying the transparent plastic overlay to the products. With those sticks, the first layer can closely wrap the product and air bubbles between the first layer and product can be avoided. 
         [0040]    For some products with flat shapes, a plastic front includes a pocket for receiving the blade where the pocket is provided with projections for engaging the blade to keep the blade from moving once inside the package. The plastic front is covered on the blade after the products are positioned on the fixture. 
         [0041]    Second step, heating a first layer of thermoplastic and positioning the fixture with product under the first layer, and applying a vacuum to the fixture to pull the first layer of thermoplastic onto the product. The first layer material could be, as an example only, a clear 0.22 to 0.25 mm hard PET sheet. The sheet is lightly heated, for example, by a heat lamp or lamps, or by warm air from a heating element or elements, and is then pushed down onto the products and then pulled down around them by conventional vacuum forming, the plate being provided with many small holes connected to a vacuum in a conventional vacuum forming manner. As shown in  FIG. 5 , the first layer  28  is above the holding fixture  21 , and above the first layer  28 , warm air  30  is blown down the first layer  28 . At the same time, antistatic airspray  29  preferably is applied. As stated in the preceding paragraph, the products preferably project above the surface of the plate, so that this step captures them, by virtue of the plastic contacting the sides of the product. However, in some cases, the plastic may adhere to the part sufficiently without the part extending substantially above the plate. 
         [0042]    The plate is then advanced out of the apparatus, pulling the PET sheet along with it to reload the apparatus. Once the plate is fully out of the apparatus, a cutter cuts the PET sheet, which is then raised for heating and for loading of the next plate, to start the process over. 
         [0043]    Third step: thermally bonding the first layer and a second layer of recycling-compatible thermoplastic to each other with the product between them, so as to capture the product. The third step of the process again involves several steps. A printed substrate layer is placed front-side-up in a fixture of another machine, for example a three-station turntable where the first station is a loading station, the second is a heat-sealing station, and the third is an unloading station. 
         [0044]    At the first station, the overlay sheet  21 , for example a pre-printed sheet of 0.43 mm thick PET with the products captured beneath it, is positioned down on to the substrate  31  as shown in  FIG. 6 . Suitable indexing pins  32  are provided, matching indexing holes in the substrate and overlay layers, to ensure proper alignment. 
         [0045]    At the second station, a heat sealing tool, preferably an ultrasonic welding machine for precise temperature and frequency control, is used to seal the substrate layer to the overlay sheet around the edges of each individual package, which could be for one product or multiple products. The heat sealing tool could also be used to seal other areas of the package if desired, not just the secure seal at the edges. However, the tightness of the overlay, and static, will generally be sufficient to hold the two plastic layers together everywhere, especially in relatively small packages. 
         [0046]    At the third station, the products can be unloaded from the apparatus. 
         [0047]    Preferably, if a number of individual packages are being formed at the same time, they are separated from each other in conjunction with the heat sealing step. Alternatively, they could be separated by die-cutting or other suitable means, as a separate step. At the same time, if desired, a conventional hang-slot can be punched out or die-cut, with a seal around its edges, so that the packaged product can be hung on a display peg at a retail outlet. 
         [0048]    Alternatively, the overlay sheet, with the products above it, could be positioned first, with the printed substrate layer then place on it face down. 
         [0049]    Normally the substrate layer will be printed on both sides, and the overlay will be transparent. Typically the substrate layer may be color-printed on the “product” side, to display typical marketing graphics, illustrations, trademarks, etc., and the back may be printed simply in black and white for such information as instructions for use, applicable warnings, company name, etc. Most convenient is to use a white plastic for the substrate, and then print on the white. What is printed on the substrate, if anything, and how it is printed, is not part of the invention. 
         [0050]    However, the invention in its preferred embodiment does provide a feature which improves an aspect of the printing on the substrate, as follows. Typically, when the substrate is printed and a plastic overlay is heat bonded to the substrate, the heat evaporates or otherwise destroys the ink at the bond location. Thus what is typically seen, if the substrate (of cardboard, for example) is printed in blue, for example, is that the area where the heat seal is located has turned white or pale blue from the applied heat. Visually, this may detract from the appearance of the package, so it would be advantageous to be able to avoid this problem. 
         [0051]    In the invention, the heat can be applied from the front or the back of the package, but preferably is applied from the back, i.e. through the substrate, which is thicker than the overlay. Without the insulating effect of cardboard or the like, the bond can be formed very quickly, with less damaging effect on the ink. There may be a visible color reduction in the area of the heat seal, but to a much lesser degree than in the prior art. 
         [0052]    In the above example, PET is the preferred plastic. However, other thermoplastics, such as PVC or PP, for example, could be used, following the process of the invention. PVC is generally a lower-cost solution, but is losing favor worldwide as the quest to reduce chlorine use expands, and in fact has now been banned from packaging in Europe. PVC packaging is the second largest use of PVC, accounting for approximately 20% of all PVC produced. It is being aggressively phased out all over Europe. It will be appreciated that other thermoplastics could be used with similar advantages, such as PP (polypropylene) for example. And as discussed above, it is conceivable that one plastic could be used for the substrate and a different plastic for the overlay, provided that the two plastics are compatible for recycling purposes. 
         [0053]    For security purposes, the packing process can also comprises steps of bonding a security tag  5  and a label to the substrate. Namely, before step  3 , UPC label substrate  45  and printed substrate  31  are heat sealed with security tag  5  sandwiched on the back side of the substrate, as shown in  FIG. 7 . This heat-sealed substrate  31  is then positioned along with the overlay in the heat sealing machine to seal, as shown in  FIG. 8 . Optionally, this step can be done after step  3 . 
       Apparatus for Packaging a Product 
       [0054]    For fulfilling the process, apparatus for packaging a product is also provided. It includes: a first station adapted for positioning the product on a vacuum-forming fixture, heating a first layer of thermoplastic and positioning it over the product, and applying a vacuum to the fixture to pull the first layer of thermoplastic onto the product; and a second station (see  FIGS. 10 and 11 ) adapted for thermally bonding the first layer and a second layer of recycling-compatible thermoplastic to each other with the product between them, so as to capture the product. 
         [0055]    It will be evident to those knowledgeable in the field of the invention that many variations on the example(s) described above are conceivable within the scope of the invention. Such variations may be apparent or become apparent to those knowledgeable in the field of the invention, within the scope of the invention as defined by the claims which follow.