Bleaching and shive reduction process for non-wood fibers

Abstract

The present invention is directed to a method of increasing the brightness of non-wood fibers and nonwoven fabric fabrics produced by the method. In one aspect, the method includes forming a mixture of non-wood fibers and exposing the mixture to a brightening agent to produce brightened fibers. The brightening agent is oxygen gas, peracetic acid, a peroxide compound, or a combination thereof. The brightened fibers have a brightness greater than the fibers of the mixture before exposure as measured by MacBeth UV-C standard.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 14 / 716,153, filed May 19, 2015, which claims benefit of U.S. Provisional Patent Application Ser. No. 62 / 000,825, filed May 20, 2014, both of which are incorporated herein in their entirety by reference.TECHNICAL FIELD[0002]The instant invention generally is related to methods for fiber production. More specifically, the instant invention is related to methods for non-wood fiber bleaching and shive reduction.BACKGROUND OF THE INVENTION[0003]Plant fibers fall into three groups: seed fibers (e.g., cotton and kapok), stem fibers (bast fibers, e.g., flax and hemp), and leaf fibers (e.g., sisal and kenaf). Bast fibers occur as bundles of fibers, which extend through the length of the plant stems, located between the outer epidermal “skin” layers and the inner woody core (cortex) of the plant. Therefore, bast fiber straw includes three primary concentric layers: a bark-like s...

AI Technical Summary

Benefits of technology

The invention has various benefits and capabilities that can be easily understood by reading the description and examples provided.

Problems solved by technology

However, a common problem still occurring in non-wood fiber processes is the occurrence of shives, which are undesirable particles in finished paper products.

Shives are substantially resistant to defiberizing processes, rendering their presence problematic.

Even following oxidative bleaching, shives continue to have deleterious effects on the appearance, surface smoothness, ink receptivity, and brightness of a finished paper product.

Mechanical removal of shive to the level required for a high value product involves the application of significant mechanical energy, which results in fiber breakage and generation of fines, or small cellulose particles.

The fines are a yield loss, increasing the production cost.

Further, the broken fibers reduce the overall fiber strength so they either cannot be used in some manufacturing processes and / or result in weak textile or paper products.

Thus, conventional methods of non-wood fiber processing are not sufficiently robust to remove, decolorize, and break up the residual shive present in the fibers.

Thus, processed and finished fibers can still include dark particles of shive, which are both aesthetically unattractive and reduce the commercial value of the fiber product.

Furthermore, conventional bleaching processes are not sufficiently robust to increase paper brightness to sufficient levels required for commercial products.

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