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Low density paperboard articles

a paperboard and low density technology, applied in the field of articles, can solve the problems of low production efficiency, low insulative properties, and low insulative properties of multi-layered and multi-walled paperboard containers, and achieve the effects of less loss in machine speed, improved insulative properties, and reduced production costs

Inactive Publication Date: 2005-06-23
MOHAN KOSARAJU KRISHNA +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention is about a low density paperboard material that can be used to make insulated containers such as cups. The paperboard material has a unique combination of properties that make it ideal for this purpose. It has a low density of about 0.25 to 0.35 g / cc, a low apparent density of about 6 to 10 lb / 3MSF / mil, and a high caliper of about 24 to 35 mil. The material also has a rough surface with a high print quality, and it is more insulating than conventional cupstock. The invention provides a method for making the low density paperboard material and converting it into insulated containers. The resulting paperboard material is cost-effective and has improved insulation compared to conventional paperboard materials."

Problems solved by technology

However, multi-layered and multi-walled paper-based containers are relatively expensive to manufacture compared to polystyrene foam-based articles and often do not exhibit comparable insulative properties.
Paperboard containers having an outer foam insulation layer are generally less expensive to produce than double-walled containers, but the outer surface is less compatible with printing.
However, the '934 patent deals with relatively low basis weight paper not suitable for insulated container manufacture, makes no mention of use of the product in the manufacture of paperboard containers having insulative properties, and gives no teaching as to how such a product could be produced so as to enable use of the product in fabricating insulative containers such as cups and the like.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0047] In the following example, samples of low density board containing microspheres were produced and compared to a sample marked “control” which contained no microspheres. Expandable microspheres used in the furnish are available from Expancel, Inc. of Duluth, Ga. of under the trade name EXPANCEL. The targeted caliper for the samples was 19 mil to simulate conventional cupstock calipers. After producing the boards, they were taken off-machine to an extruder and extrusion coated with low density polyethylene at a rate of 14 lbs / 3MSF to provide a barrier coating on one side having a thickness of about 1 mil. All of the samples except Sample D contained the polyethylene coating. Sample D had insufficient strength and was too brittle to be extrusion coated with polyethylene. The polyethylene-coated samples were converted to 16 oz. cups on a commercial cup machine. The insulative properties of the cups were determined by measuring the time a person could hold a cup filled with hot wat...

example 2

[0052] In the following example, two different low density board stocks were made having densities in the range of from about 6 to about 10 lb / 3MSF / mil and from furnish containing expandable microspheres. The board stock thus made was converted to 16 oz. cups. The physical properties of the board stock are shown in Table 2. All of the samples in Table 2 were coated with low density polyethylene on an extrusion line and printed on an aqueous flexo press. The coating was applied to one side of the board at about 20 mil and the printing was applied to the other side.

[0053] The coated board indicated as Sample 19 was converted to cups on a commercial machine with existing tooling. The board indicated as Sample 32 was converted to cups using prototype tooling on a commercial cup machine. The rims of the cups formed using the prototype tooling were only partially formed. Modification of the tooling will enable completely formed cups.

TABLE 2SampleSampleSamplePropertiesControl271932Softw...

example 3

[0059] In the following example, eight low density board stocks were made having densities in the range of from about 6 to about 10 lb / 3MSF / mil and from furnish containing expandable microspheres. The board stock thus made was converted to 16 oz. cups. The physical properties of the board stock are shown in Table 3. All of the samples in Table 3 were coated with low density polyethylene on an extrusion line and printed on an aqueous flexographic press. The coating was applied to one side of the board at about 1.5 mil and the printing was applied to the other side directly on the paper surface.

[0060] Samples P1 and P2 were manufactured on a pilot papermachine and extruded on a pilot extruder whereas samples C1 through to C5 were manufactured on a commercial papermachine. In both cases, the papermaking furnish used to produced these samples contained a blend of hardwood and softwood pulps and wet-end chemicals, such as starch and dry strength additives, and a suitable amount of expan...

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Abstract

The invention provides a low density paperboard material and associated method for use in producing an insulated container, and is especially well-suited for making cups. The paperboard material comprises a paperboard web including wood fibers and expanded microspheres, and has a relatively low density ranging from about 6 to about 10 lb / 3MSF / mil, a relatively high caliper ranging from about 24 to about 35 mil, and an internal bond strength of at least about 80×10−3 ft−lbf., preferably at least 100×10−3 lft−lbf. For applications such as cups the material is also coated on one or both sides with a barrier coating, preferably low density polyethylene, to limit liquid penetration into the web. The low density paperboard material of the invention is convertible for manufacture of containers, particularly cups, and exhibits insulative properties comparable to higher cost materials conventionally used to make cups. Also, the surface of the low density board may have a Sheffield smoothness of 300 SU or greater compared with the surface smoothness of 160 to 200 SU for conventional cupstock, the latter having been thought necessary for adequate print quality. However, it has been found that the low density board exhibits good printability on flexo printing machines despite its relatively rough surface, which is surprising and bonus effect realized along with the insulative and other properties of the board.

Description

FIELD OF THE INVENTION [0001] This application is a continuation-in-part of copending provisional application Ser. No. 60 / 178,214, filed Jan. 26, 2000. [0002] This invention relates generally to the production of articles from low density paper and paperboard and to insulated articles made therefrom, and in particular, relates to cups made of low density paper and paperboard. BACKGROUND AND SUMMARY OF THE INVENTION [0003] Insulated cups and containers are widely used for serving hot and cold beverages and other food items. Such articles may be made from a variety of materials including polystyrene foam, double-walled containers, and multi-layered paper-based containers such as paperboard containers containing an outer foamed layer. Paper-based containers are often more desirable than containers made from styrene-based materials because paper-based materials are generally more amenable to recycling, are biodegradable and have a surface more acceptable to printing. However, multi-laye...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B65D3/22A47G19/22A47J41/00B32B1/00B32B5/24B65D5/43B65D5/56B65D65/02B65D65/42B65D81/38D21H19/20D21H19/22D21H19/28D21H21/54D21H21/56D21H27/10
CPCD21H19/20D21H19/22D21H19/28D21H21/54D21H27/10Y10T428/254Y10T428/24455Y10T428/24355Y10T428/1348Y10T428/273Y10T428/25Y10T428/277Y10T428/2985Y10T428/1303Y10T428/31993Y10T428/31989Y10T428/31902
Inventor MOHAN, KOSARAJU KRISHNAKOUKOULAS, ALEXANDER A.FROASS, PETER MATTHEWREED, DAVID VERD
Owner MOHAN KOSARAJU KRISHNA
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