Disposable lid having polymer composite of polyolefin and mineral filler

Abstract

Disposable lid comprises a thermoformed sheet in the shape of a lid for a hot beverage container. The sheet comprises a polymer composite of a polyolefin and at least one mineral filler. The sheet has a thickness less than about 0.035 inches and a heat deflection temperature at least comparable to that of high impact polystyrene.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of and priority to U.S. Provisional Application Ser. No. 61 / 477,886, filed Apr. 21, 2011, which is hereby incorporated by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present application generally relates to polymer compositions particularly suited for disposable lids and the like. Particularly, the present application relates to a disposable lid comprising a thermoformed sheet having a polymer composite of polyolefin and at least one mineral filler.[0004]2. Description of Related Art[0005]Hot beverages, such as freshly brewed coffee for people on the go, are usually served in heavy paper cups with disposable lids. Coffee is typically brewed at 90-96° C., held at 82-88° C. and served at 70-80° C. A coffee cup lid preferably has a mechanical strength to withstand the force required to push the lid onto the cup and to maintain the dimensional stability at t...

AI Technical Summary

Benefits of technology

[0007]To achieve these and other advantages and in accordance with the purpose of the application, as embodied and broadly described, the application includes a disposable lid comprising a thermoformed sheet in the shape of a lid for a hot beverage container. The sheet comprises a polymer composite of a polyolefin and at least one mineral filler. The sheet has a thickness less than about 0.035 inches and a heat deflection temperature at least comparable to that of high impact polystyrene.

[0008]In accordance with one aspect, the heat deflection temperature can be at least about that of high impact polystyrene. Particularly, the heat deflection temperature according to ASTM D648-06 Standard Test Method for Deflection Temperature of Plastics Under Flexural Load in the Edgewise Position (2006) can be at least about 87° C.

[0009]As embodied herein, the mineral filler can include a high aspect ratio mineral filler, for example, selected from the group consisting of talc, mica, wollastonite, or combinations thereof. For example, the polymer composite can comprise at least about 10% by weight of the high aspect ratio mineral filler. Additionally or alternatively, the mineral filler can include a low aspect ratio mineral filler, such as calcium carbonate. For example, the polymer composite can comprise at least about 20% by weight of the low aspect ratio mineral filler. The polyolefin can be selected from the group consisting of polypropylene homopolymer, polypropylene impact copolymer, ethylene-propylene random copolymer, high density polyethylene, or combinations thereof.

[0010]In one embodiment, the polyolefin includes polypropylene, the mineral filler includes a high aspect ratio mineral filler, and the polymer composite comprises at least about 10% by weight of the mineral filler. In another embodiment, the polyolefin includes polypropylene, the mineral filler includes a low aspect ratio mineral filler, and the polymer composite comprises at least about 20% by weight of the mineral filler. In yet another embodiment, the polyolefin includes high density polyethylene, the mineral filler includes a high aspect ratio mineral filler, and the polymer composite comprises at least about 20% by weight of the mineral filler. In yet another embodiment, the polyolefin includes high density polyethylene, the mineral filler includes a low aspect ratio mineral filler, and the polymer composite comprises at least about 40% by weight of the mineral filler.

[0011]In accordance with another aspect, the polyolefin can include polypropylene, the mineral filler can include a high aspect ratio mineral filler, and the polymer composite can have a shrinkage comparable to that of high impact polystyrene. For example, the polymer composite can have a shrinkage of about 0.5% to about 1.0% when measured according to the ASTM D955 standard (1996). In this manner, the polymer composite comprises about 20% to about 40% by weight of the mineral filler.

[0012]In accordance with another aspect, the polyolefin can include polyethylene, the mineral filler can include a high aspect ratio mineral filler, and the polymer composite can have a shrinkage comparable to that of polypropylene. As such, the polymer composite can have a shrinkage of about 1.25% to about 1.75% when measured according to the ASTM D955 standard (1996). In this embodiment, the polymer composite comprises about 30% to about 50% by weight of the mineral filler.

Problems solved by technology

However, high impact polystyrene resin can be susceptible to chemical attack and solvent crazing.

In addition, the presence of residual styrene monomer in the resin can cause an unpleasant odor.

Furthermore, high impact polystyrene resin, amongst all the commodity resins, has a comparatively high carbon footprint.

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