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  Foam-paperboard laminates, articles incorporating same and methods of making the sameUSPTO Application #: 20060286325Title: Foam-paperboard laminates, articles incorporating same and methods of making the same Abstract: The present invention relates to foam-paperboard laminates (foam-paperboard laminates) prepared using an in situ foaming process. The foam-paperboard laminates of the present invention are formed by extruding LDPE polymer onto a moisture containing paperboard to provide a LDPE-coated paperboard material. Upon heating of the LDPE-coated paperboard, the moisture in the paperboard causes steam to act as a blowing agent for the LDPE and a LDPE foam is obtained. The foam is adhered to the paperboard by way of physical adhesion of the polymer to the paperboard. The foam-paperboard laminates of the present invention exhibit insulating and cushioning properties. The foam-paperboard laminates are suitable for use, for example, in insulating beverage cups, food service containers, packaging material, and in other products where laminates can be useful. (end of abstract) Agent: Patent Group Ga030-43 Georgia-pacific Corporation - Atlanta, GA, US Inventors: Dean P. Swoboda, Rana Shehadeh, Anthony J. Swiontek, Gregory J. Anderson USPTO Applicaton #: 20060286325 - Class: 428036500 (USPTO) Related Patent Categories: Stock Material Or Miscellaneous Articles, Hollow Or Container Type Article (e.g., Tube, Vase, Etc.), Polymer Or Resin Containing (i.e., Natural Or Synthetic), Foam Or Porous Material Containing The Patent Description & Claims data below is from USPTO Patent Application 20060286325. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Application Nos. 60/691,404, filed Jun. 17, 2005 and 60/705,605, filed Aug. 4, 2005. The disclosures of each of these applications are incorporated herein in their entireties by this reference. FIELD OF THE INVENTION [0002] The present invention relates to foam-paperboard laminates prepared using an in situ foaming process. The foam-paperboard laminates of the present invention are formed by extruding LDPE polymer onto a moisture-containing paperboard to provide a LDPE-coated paperboard material. Upon heating of the LDPE-coated paperboard, the moisture in the paperboard causes steam to act as a blowing agent for the LDPE and a LDPE foam is obtained. The foam is adhered by way of physical adhesion of the polymer to the paperboard. The foam-paperboard laminates of the present invention exhibit insulating and cushioning properties. The foam-paperboard laminates are suitable for use in, for example, insulated beverage cups, food service containers, packaging materials, and in other products where insulating and/or cushioning laminate materials can be useful. BACKGROUND OF THE INVENTION [0003] Foam-paperboard laminates prepared using in situ foaming processes are known for use in insulated beverage cups that are sold commercially as PerfecTouch.RTM. by the assignee of the present invention. The basic technology used to prepare the foam surface of the cups is disclosed in U.S. Pat. No. 4,435,344 to Iioka, the disclosure of which is incorporated herein in its entirety by this reference. [0004] To make this product, generally, the beverage cup is fabricated to include a bottom panel and a sidewall, both of which are made of paperboard material. Prior to application of the bottom panel, LDPE is extruded to one surface of the sidewall material. A blend of LDPE and HDPE is extruded to the other side of the sidewall material. Foaming of the LDPE-coated outer sidewall surface is carried out in situ by placing the unfoamed beverage cup in an oven and heating it above the melting point of the outer LDPE coating. The moisture within the paperboard causes steam to form and, since steam occupies more volume than liquid water, pressure is created, thus providing a foaming action on the LDPE-coated outer cup surface. The HDPE/LDPE layer on the inside of the cup prevents steam from escaping toward the interior of the beverage cup to result in preferential foaming of the outer layer. Cups made in this manner exhibit superior insulating properties, especially with respect to hot liquids such as coffee, tea, and the like. The cups are also suitably used for cold beverages. [0005] Refinements in the manufacturing of the in situ foaming process are disclosed in U.S. Pat. No. 5,993,705 to Grishchenko et al. (incorporated by reference herein). In the '705 patent, containers are conveyed through an oven on a conveyor to cause a foamable material on the container to foam and become a heat insulative layer. The containers are supported on respective holders of the conveyor which prevent the containers from contacting one another while the outer coatings on the container walls are foamed. See also U.S. Pat. No. 6,328,557 to Grishchenko et al. (incorporated by reference herein). [0006] While PerfecTouch insulated cups have been manufactured for a number of years, recently this product has experienced significantly increased demand. In attempting to meet this demand, it was determined that using existing processes and materials, suitable foam qualities could not be obtained using web speeds of greater than about 300 feet per minute. [0007] It was thus determined that it would be desirable to develop improved methods to conduct an in situ foaming process more efficiently. Still further, it was determined that it would be desirable to obtain suitable foam quality using less polymer than was possible using previous processes and materials. The present invention meets these objectives, as well as others. SUMMARY OF THE INVENTION [0008] In one aspect, the present invention provides foam-paperboard laminates prepared from LDPE having a MI of greater than 8 to about 20 g/10 min, as measured by ASTM 1298. In a further form, the foam aspect of the foam-paperboard laminates of the present invention is prepared by one or more methods of reducing the orientation of an extruded LDPE coated on the paperboard. The foam is obtained by first extruding the LDPE onto the paperboard to provide a LDPE-coated paperboard material. The material is then heated to provide steam release from the paperboard. The steam operates as a blowing agent and causes the LDPE to foam in situ. Upon completion of the foaming process, the LDPE foam is physically adhered to the paperboard to provide a foam-paperboard laminate. The foam-paperboard laminates of the present invention are suitable for use in insulated beverage cups, packaging materials, as well as many other products. Using LDPE as specified herein, it has been found possible to manufacture foam-paperboard laminates at significantly higher speeds than previously allowable. Moreover, the characteristics of the foam prepared in accordance with the present invention are significantly improved over foams prepared using prior art methods. [0009] Additional advantages of the invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. BRIEF DESCRIPTION OF THE DRAWINGS [0010] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. [0011] The invention is described in detail below with reference to the Figures, wherein like numbers designate similar parts and wherein: [0012] FIG. 1 is a schematic view in elevation and section of an insulated beverage cup prepared from a foam-paperboard laminate of the present invention; [0013] FIG. 1a is a detail of the insulated beverage cup of FIG. 1 showing the various layers schematically in the area where the bottom panel is joined to the paperboard sidewall. [0014] FIG. 2 is a schematic diagram illustrating coating of paperboard with a LDPE using a slit die apparatus. [0015] FIG. 2a is a schematic view of a foam-paperboard laminate in accordance with an aspect of the present invention comprising an occlusive layer on an interior side, and a LDPE foam layer on the other side. [0016] FIG. 3 is a photomicrograph in section of a foam-paperboard laminate where LDPE having a melt index of 5.7 g/10 min was applied to the paperboard at a web speed of 200 ft/min. [0017] FIG. 4 is a photomicrograph in section of a foam-paperboard laminate where LDPE having a MI of 5.7 g/10 min was applied to the paperboard at a web speed of 450 ft/min, where the extrusion conditions were not optimized. [0018] FIG. 5 is a photomicrograph in section of a foam-paperboard laminate where LDPE having a MI of 5.7 g/10 min was applied to the paperboard web speed of 200 ft/min. [0019] FIG. 6 is a photomicrograph in section of a foam-paperboard laminate where LDPE having a MI of 5.7 g/10 min was applied to the paperboard at a web speed of 450 ft/min where the extrusion conditions were not optimized. Continue reading... Full patent description for Foam-paperboard laminates, articles incorporating same and methods of making the same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Foam-paperboard laminates, articles incorporating same and methods of making the same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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