Water stable fibers and articles comprising starch, and methods of making the same

Abstract

Water stable fibers and articles made therefrom are formed from a thermoplastic composition comprising destructured starch, polyhydric alcohol, acid, and optionally triglyceride. Processes for making water stable compositions may comprise melt extruding a mixture of destructured starch, polyhydric alcohol, acid, and optionally triglyceride, to form an extrudate, and heating the mixture, extrudate, or both to provide a water stable article.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of U.S. Provisional Application No. 60 / 725,424, filed 11 Oct. 2005.FIELD OF THE INVENTION [0002] The present invention relates to fibers made from thermoplastic starch compositions, and articles made therefrom. The fibers and articles are water stable, or may be rendered so. The invention also relates to methods of making the fibers and articles. BACKGROUND OF THE INVENTION [0003] There have been many attempts to make starch-containing fibers, particularly on a high speed industrial level. However, starch fibers can be much more difficult to produce than films, blow-molded articles, and injection-molded articles containing starch because the material and processing characteristics for fibers are much more stringent. For example, local strain rates and shear rates can be much greater in fiber production than in other processes. Additionally, a homogeneous composition may be required for fiber spinning. ...

AI Technical Summary

Benefits of technology

[0009] In general, the present invention provides starch-based compositions, fibers and articles in other forms with improved water stability, and compositions and processes for making such water stable compositions and articles. Water stability may be achieved without requiring the use of petroleum based polymers including, but not limited to, polyolefins. Water stability can provide a variety of consumer-related benefits. The fibers, compositions and processes may provide a low-cost alternative to conventional petroleum-based materials. These and additional advantages will be more apparent in view of the following detailed description.

Problems solved by technology

However, starch fibers can be much more difficult to produce than films, blow-molded articles, and injection-molded articles containing starch because the material and processing characteristics for fibers are much more stringent.

For spinning fine fibers, small defects, slight inconsistencies, or non-homogeneity in the melt are typically not acceptable for current, commercially viable processes.

Unpredictable fluctuations in price and availability of petroleum and its derivatives have created serious disruptions to the stable supply of petroleum-based polymers used in making synthetic fibers, for example, those based on polyolefins.

Unfortunately, thermoplastic starch (TPS) is highly susceptible to moisture.

In fact, fibers made of TPS can spontaneously pick up atmospheric moisture and become tacky.

Although methods exist for rendering thermoplastic compositions containing starch more water stable including, but not limited the addition of petroleum based polymers, there remains an unmet need for greater water stability in such compositions and in articles made from such compositions.