Compositions for manufacturing fiber-reinforced, starch-bound articles having a foamed cellular matrix

Abstract

Compositions, methods, and systems for manufacturing articles, particularly containers and packaging materials, having a fiber-reinforced, starch-bound cellular matrix. Suitable mixtures used to form the articles are prepared by first preparing a viscous preblended mixture comprising water, a gelatinized starch-based binder, and fibers having an average length greater than about 2 mm. The highly viscous preblended mixture effectively transfers the shearing forces of the mixer to the fibers. The final moldable mixture is then prepared by mixing into the preblended mixture the remaining starch-based binder, water, and other desired admixtures, e.g., mold-releasing agents, inorganic filler rheology-modifying agents, plasticizers, coating materials, and dispersants, in the correct proportions to form an article which has the desired performance criteria. The moldable mixtures are heated between molds at an elevated temperature and pressure to produce form-stable articles having a desired shape and a selectively controlled foamed structural matrix. The articles may be manufactured to have properties substantially similar to articles presently made from conventional materials like paper, paperboard, polystyrene, plastic, or other organic-based materials and have especial utility in the mass-production of containers, particularly food and beverage containers.

Description

[0001]This application is a continuation-in-part of U.S. Ser. No. 08 / 288,664, filed Aug. 9, 1994, now allowed, and a continuation-in-part of U.S. Ser. No. 08 / 288,667, filed Aug. 9, 1994, pending U.S. Ser. No. 08 / 288,667 is a continuation-in-part of U.S. Ser. No. 08 / 218,971, filed Mar. 25, 1994, pending, and a continuation-in-part of U.S. Ser. No. 08 / 109,100, filed Aug. 18, 1993, now abandoned, and a continuation-in-part of U.S. Ser. No. 08 / 095,662, filed Jul. 21, 1993, now U.S. Pat. No. 5,385,764, and a continuation-in-part of U.S. Ser. No. 07 / 982,383, filed Nov. 25, 1992, now abandoned, and a continuation-in-part of U.S. Ser. No. 07 / 929,898, filed Aug. 11, 1992, now abandoned. U.S. Ser. No. 08 / 288,664 is a continuation-in-part of U.S. Ser. No. 07 / 928,898, filed Aug. 11, 1992, now abandoned. For purposes of disclosure of the present invention, each of the foregoing applications is incorporated herein by specific reference. BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0...

AI Technical Summary

Benefits of technology

[0102]FIG. 22 shows a graph illustrating the effect of including varying amounts of pregelatinized starch on yield stress;

[0103]FIG. 23 shows a graph illustrating the effect of including varying mounts of pregelatinized starch on viscosity;

[0104]FIG. 24 shows a graph illustrating the effect of shear rate on viscosity for a predicted mixture containing 50 g starch and 800 g water;

[0105]FIG. 25

Problems solved by technology

Without the conditioning step to reintroduce moisture back into the starch-based matrix, foamed starch-based articles, even those that include quantities of shorter-length fibers, were usually too brittle and fragile for their intended use.

Moreover, such articles could not simply be demolded without such overdrying bec

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