Abstract:
A recyclable blister pack system is provided, including a substrate having a dry tack adhesive layer deposited on one of its surfaces and a blister layer for receiving a product. The properties of the dry tack cohesive are selected so the blister layer is separable from the substrate without leaving substantial substrate residue on the blister layer. This improves the recyclability of the blister layer.

Description:
REFERENCE TO PRIOR APPLICATIONS  
       [0001]     The present application claims the benefit of U.S. provisional application Ser. No. 60/999,329, filed Oct. 17, 2007.  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates to an easily recyclable blister pack system and to the process of making.  
       DESCRIPTION OF THE RELATED ART  
       [0003]     Consumer packaging has evolved from simple cartons that protected the product, but which required opening the carton to view the contents, to blister/card packages that encapsulate the product while still allowing viewing the product, to thermoformed clamshell containers that allow tamper-proof viewing of the finished product. Each step in the evolution of the packaging has increased the cost of the package, the amount of hydrocarbons required for manufacture, and reduced the opportunity for recycling the packaging materials following removal of the product.  
         [0004]     In the case of card/blister packages, the product is inserted into a thermoplastic blister that is then heat-sealed (at elevated temperature and pressure) to a printed chipboard card that has been coated with a heat-sensitive adhesive. When the product is removed from the package, the adhesive and fibers bond to the blister, and prevent efficient recycling of the blister material. In addition, the card/blister packages are subject to size and weight limitations because the assembled package must fit into heat-sealing machines.  
         [0005]     In the case of clamshell packages, the product is inserted into a transparent thermoplastic shell that fully encloses it. The shell consists of two halves joined by a hinge made of the materials found in the shell. The clamshell is folded in half to form an enclosure that completely encloses the packaged product. The two halves of the assembled halves, or by means of a mechanical fastener such as a staple. For heavy or high value products, the shell may be heat or radio frequency (RF) sealed for tamper resistance, but the heat-sealing operation frequently causes customer dissatisfaction due to the extreme difficulty in opening the pack to use the product. In addition, the clamshell package uses two to three times the hydrocarbons required for a card/blister package. The clamshell materials are not easily separable for recycling.  
         [0006]     Consumers are increasingly concerned with the excessive amounts of plastic, cardboard and paper associated with the packaging of consumer products, as are various enviromental conservation groups. Some major consumer product retailers have also expressed dissatisfacton with currently available consumer product packaging options, especially those with a high impact to the environment.  
         [0007]     One such national retailer has developed a “sustainability scorecard” that measures the environmental impact of the packaging used for consumer products. The sustainability scorecard is used to reward suppliers that have developed or utilized sustainable packaging products and technology. Suppliers that do not use sustainable packaging will be at a competitive disadvantage.  
         [0008]     By way of example, the sustainability scorecard oncludes the the following factors that are considered: greenhouse gasses (e.g. carbon dioxide (CO2) created per ton of packaging production, material value, product-to-package ratio, cube utilization, cost of transportation, total recycled content, recovery value, renewable energy use in production, and innovativeness.  
         [0009]     Accordingly, there is a recognized need for new packaging products and packaging manufacturing techniques that minimize impact to the environment throughout the entire life cycle of the product from manufacture through sale, use and ultimate disposal.  
         [0010]     It is an object of the invention to provide a packaging system that meets the sustainability scorecard targets and offers significantly improved recyclability  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention provides an easily and efficiently recyclable packaging system for consumer products capable of incorporating full color graphics, tamper and theft resistance, use of recycled materials (SPET bilater and post-consumer corrugate) and a dry tack cohesive adhesive. The packaging consists of these components; a die-cut substrate (a corrugate body in the preferred embodiment), a thermoformed RPET blister layer, and a dry tack cohesive adhesive.  
         [0012]     In its simplest form, the invention comprises a substrate having first and second regions, a dry tack cohesive layer applied to the first and second regions, and a blister layer for accepting a product and having a surface along its periphery capable in use of capture between the dry tack cohesive layers. The adhesive properties of the cohesive layers are selected such that it is capable of forming a seal only with itself and the substrate, and so it is separable from the blister layer without leaving substrate residue to facillitate recyclability.  
         [0013]     In the preferred embodiment, the invention comprises a blister pack system including a substrate having a first and second regions with at least one of the regions having an opening formed therein for receiving a product, a dry tack cohesive layer applied to the first and second regions, and a blister layer shaped to accept a product and having a surface along its periphery capable in use of capture between the dry tack adhesive layer on the first and second regions. The adhesive properties of the cohesive layer are selected such that it is capable of forming a seal only with itself and the substrate, and so that it is separable from the blister layer without leaving substrate residue to facilitate recyclability.  
         [0014]     The process for assembling the blister pack system includes the steps of forming a dry tack adhesive layer above a substrate having first and second regions, with one of the regions having an opening formed therein, the substrate is folded along a line dividing the first and second regions and the blister layer positioned between the first and second regions of the substrate so the shaped portion of the blister layer accepts a product and passes through the opening formed in the substrate, and so that its peripheral surface is between the first and second regions having the dry tack cohesive layer formed thereon. The system is sealed by applying pressure to the substrate along the peripheral surface of the first and second regions. The cohesive adhesive adheres to itself thereby holding the blister layer securely in place. The adhesive properties of the cohesive layer are selected such that it is capable of forming a seal only with itself and the substrate, and so it is separable from the blister layer without leaving substrate residue to facilitate recyclability.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a top view of the die-cut substrate or corrugate body.  
         [0016]      FIG. 2  depicts the thermoformed RPET blister layer.  
         [0017]      FIG. 3  is a schematic representation of the bottom single roll coating process.  
         [0018]      FIG. 4  shows an assembled blister pack system with the product&#39;s installed in the blister layer, and the blister layer installed in the corrugate body. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]      FIG. 1  shows a planar substrate  10 , which is the preferred embodiment is corrugate body having a generally rectangular shape, but which can also be a chipboard material. Although not shown in  FIG. 1 , substrate  10  may be pre-printed with a color graphic label describing the product (also not shown), The substrate is generally divided into two halves or regions  12  and  14  separated by a centerline  16  which, to facilitate folding of the substrate, may be formed by scoring or perforation. A pair of die-cut openings  18  and  20  are formed, respectively, in regions  12  and  14  of the substrate. While two openings  18  and  20  are shown in  FIG. 1 , not all packaging applications requires both openings. The die-cut openings generally approximate the outline of the product being packaged. Substrate  10  is sized to allow approximately a one inch sealing area  22  along the perimeter of the substrate and surrounding the die cut openings, as suggested by dotted line  24 . The width and shape of sealing area  22  can be varied to suit the size and weight of the product to be packaged. Larger, heavier products typically require a wider sealing area to ensure integrity of the package.  
         [0020]     The thermoformed blister layer  30 , shown in  FIG. 2 , is produced preferably from recycled polyethylene terepthlate (RPET) resin with a normal thickness of 10-15 millis (0.010-0.015 in). The blister layer is produced in a well known manner by placing RPET film into a forming dye (not shown) under heat and pressure. IN the preferred embodiment, the die closely approximates the shape of the product or products to be packaged and forms regions or volumes  32  for receiving the product. The blister layer design incorporates a flange  34  disposed generally between perimeter  36  of the blister layer and edges  38  of regions  32 . In the preferred embodiment, flange  34  is approximately 0.38 in. wide. The flange serves to contain the blister layer and product(s) within a substrate lamination formed when the corrugate body is folded along line  15  ( FIG. 1 ) and sealed as described hereinafter. In those instances when it is desirable that the packaged product be viewable from both sides, a second blister layer (a mirror image of the first) needs to be formed. One blister layer is installed into substrate openings  18  and  20  ( FIG. 1 ).  
         [0021]     The unique properties of the dry tack adhesive are a critical element of the package. The adhesive is a formulated latex rubber product that is applied in aqueous (water-based) liquid form, but which dries as a dry tack adhesive (also referred to as a cohesive) which adheres to itself and the substrate, but not to most other surfaces such as the blister layer. This selective adherence property enables the blister layer to be removed or separated for recycling without adhesive residue or fibrous residue material from the substrate, especially a corrugate substrate, remaining on it. This facilitates efficient recycling of the RPET material. The adhesive properties are carefully controlled to create an environmentally acceptable adhesive with unique cohesive properties that also enable handling and transportation of the coated, unsealed substrates without blocking (i.e. the sticking of substrates to one another).  
         [0022]     In the preferred embodiment, the physical properties of the adhesive are aqueous solution, solids 66% by weight viscosity (dry aged) of approximately 4000 CPS (Centipoise) in 3 months; rheaology—highly pseudo-plastic and thixotropic, with a ratio of viscosity at one RPM (revolution per minute) to viscosity at 50 RPM of approximately 14. : pH—alkaline approximately 10.5 ammonical, viscosity (liquid form)—1330 CPS. The viscosity is controlled at application by thinning with water.  
         [0023]     The adhesive is applied to the substrate using a conventional roll coating machine. In the preferred embodiment, the single bottom roller coating process is utilized.  FIG. 3  shows a typical arrangement. Substrate  10  is positioned for linear movement between rollers  38  and  40 . Adhesive is dispensed onto unprinted substrate surface  42  and is spread uniformly by roller  38 , as the substrate advances in the direction indicated by arrow  48 . The single bottom roll coating process is used to ensure a uniform coating on the unprinted side  42  of the substrate. Care must be taken to prevent transfer of the cohesive to the printed (finished) side  46  of the substrate. Once the substrate has been coated, it is air dried or heat-dried to produce a tack-free surface. Finished adhesive-coated substrates should be stored in a dry, temperature controlled area maintained at between 40-100 degrees Fahrenheit, and protected from dust and light, especially ultraviolet (UV) light.  
         [0024]     Actual packaging of products using the blister pack system is relatively straight forward and typically occurs at a location different from where the substrate coating and blister layer operations occurred. Referring now to  FIGS. 1-4 , the products  50  to be packaged and blister layers  30  (assuming the products are to be viewed from both sides) are placed into die-cut openings  18  and  20  of the substrate, and the substrate folded along line  16 . Substrate body  10  is folded so that the cohesive-coated surface  42  on each substrate region  12  and  14  are brought together in sealing area  52  ( FIG. 4 ) lying generally outside blister layer perimeter  36  and the outside edges of the substrate  10  and hold flange  34  there-between. Once the substrate has been forced to contain the blister layers and products, area  52  must be pressure-sealed to ensure a complete bond between the two substrate surface along area  52  to firmly hold flange  34  of the blister layer in place. Adequate pressure is required to develop the bond. This pressure can be produced by the use of a manual or mechanical weighted roller, or other mechanical means (including commercially available card/blister sealing machines), as long as the resulting pressure is sufficient to bond the cohesive, thereby producing a finished laminated package which contains the products and blisters between the substrate, as shown in  FIG. 4 .  
         [0025]     It will be appreciated that utilization of perimeter sealing of the substrate, as disclosed, results in a tamper-resistant package and enables packaging of heavy products.  
         [0026]     The invention has been disclosed with reference to its preferred embodiment. It will be recognized, however, that variations are possible. For example different types of substrate materials such as corrugate or chipboard may be used. Similarly, substrates of different thicknesses may be used based upon the size and weight of the product to be packaged. Different printing techniques may also be used to create the graphics on the substrate. Different adhesive formulations may be usded instead of the specific cohesive formulation disclosed herein, but the selected adherence properties and ability to handle and ship coated substrates prior to assembly is a critical element of the package.  
         [0027]     The foregoing description of one of the embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosd. Many modifications and variations are possible in light of the above description, without fundamentally deviating from the essence of the present invention. It is intended that the scope of the invention not be limited by this description.