Biodegradable polyesters for use in forming fibers

Abstract

A method for forming a biodegradable polyester suitable for use in fibers is provided. Specifically, a biodegredable polyester is melt processed at a controlled water content to initiate a hydrolysis reaction. Without intending to be limited by theory, it is believed that the hydroxyl groups present in water are capable of attacking the ester linkage of the polyester, thereby leading to chain scission or ''depolymerization'' of the polyester molecule into one or more shorter ester chains. By selectively controlling the reaction conditions (e.g., water content, temperature, shear rate, etc.), ahydrolytically degraded polyester may be achieved that has a molecular weight lower than the starting polymer. Such lower molecular weight polymers have a higher melt flow rate and lower apparent viscosity, which are useful in a wide variety of fiber forming applications, such as in the meltblowing of nonwoven webs.

Description

Background of the invention [0001] Biodegradable nonwoven webs have a wide variety of applications, such as in disposable absorbent products (eg, diapers, training pants, hygiene wipes, feminine pads and liners, adult incontinence pads, braces, garments, etc.). To facilitate nonwoven web formation, the selected biodegradable polymer should be melt processable and have good mechanical and physical properties. Although various attempts have been made to use polyesters in the formation of nonwoven webs, their relatively high molecular weight and viscosity tend to limit their use to only certain types of film forming processes. For example, conventional aliphatic polyesters are generally not suitable for meltblowing processes, which require low polymer viscosities for efficient formation of microfibers. Accordingly, there remains a need for biodegradable polyesters with good mechanical and physical properties that can be readily formed into nonwoven webs using a variety of techni...

AI Technical Summary

Problems solved by technology

Although various attempts have been made to use polyester in the formation of nonwoven webs, its relatively high molecular weight and viscosity tend to limit its use to only certain types of film forming methods

For example, conventional aliphatic polyesters are generally not suitable for melt blowing, which requires low polymer viscosity for efficient formation of microfibers

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