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.

Description

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, fo...

AI Technical Summary

Benefits of technology

[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.

Problems solved by technology

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.

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