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USDA task force meets to chart future of cotton.

USDA Task Force Meets To Chart Future Of Cotton Of all of the subjects concerning cotton nonwovens, the one that drew the most attention was biodegradability. Views on the importance of biodegrability were mixed. Some considered it an essential part of any work involving cotton, since this is one of its advantages over synthetic fibers. Likewise, biodegrability is considered to be one of more viable solutions to the solid waste problem. It should be of major concern to the nonwovens industry.

Other members of the Task Force pointed out that a biodegradable product offered no advantage over plastics because of the current landfill conditions. However, it was pointed out that composting is gaining in popularity and is now being considered as a viable option for solid waste management. Biodegrable products would have a distinct advantage if this method of waste disposal were used. At least one member of the Task Force contended that the major effort of waste disposal should be directed toward recycling. This is the approach advocated by the plastic industry.

The statement was made that consumers appear to be confused about the term "biodegradable." One member commented that environmental groups actually protest material that are biodegradable because some of these were reported to release materials that were toxic and caused more harm after being degraded. However, this line of reasining was questioned since not enough scientific data had been collected. It was also pointed out that if biodegradability was causing confusion among consumers it was because of the plastics industry's attempt to market biodegradable products that truly do not degrade in the same sense that cotton degrades. The consensus of the Task Force was that a true definition of biodegradable was needed.

Wanted: Better Technology For Cotton

It was expressed by more than one member of the Task Force that the major reason why more cotton is not used by the nonwovens industry is the lack of a suitable finish that will allow bleached cotton to be processed (carded) at the same speeds as synthetic fibers.

At present, the maximum speed for carding a quality cotton web is approximately 200 feet a minute, which is half the speed at which synthetics can be processed. A finish that will increase production speeds for cotton is needed. Finishing of cotton fiber is also important for processing on needle looms as well. A proper finish will reduce fiber damage, prevent needle breaks, increase production speeds and improve fabric properties.

At this time, the problem of fiber finishing and mechanical processing are somewhat beyond the realm of the current USDA nonwovens project. The concensus was that the a major hurdle to utilization of cotton in nonwovens could be scaled if these problems could be solved. There are several areas in which cotton could be used if there was a source of cotton with consistently good processability.

This was food for thought for Cotton Inc. and the Fiber Quality Research Unit at SRRC. The lubricant finishing research now being conducted by Thibodeaux and Calamari to improve yarn spinning could possibly be extended to improving the carding efficiency of bleached cotton. Quality of the web should not be sacrificed at the expense of production speed. Properties such as nep formation, dust and trash contents should be considered. It is more than likely that different finishes will be required depending on the end use of the product.

Other questions that require answers are: Is production speed a problem with cotton blends as well--for example, a 80/20 cotton/polypropylene blend? What about 70/30 or 50/50 blends? If a 50/50 cotton/polypropylene mixture is placed in the hopper, then blended, carded and calendered, does the fabric contain the same 50/50 ratio? That is, are the cotton and polypropylene fibers in a blend processed at the same rate or is cotton fiber lost in carding?

Equipment must be in excellent shape in order to process cotton at higher speeds. Equipment manufacturers could play an important role in improving production speed and they should be consulted. It is possible that cards could be modified to increase efficiency. It was pointed out that when emphasis switched from rayon to polyester many years ago, processing was a "big headache." Complaints were numerous, but the switch was made.

At present, 75-80 million pounds of cotton a year are used in nonwovens. However, cotton is not used in what might be considered high tech areas. Most cotton is used in products such as cotton swabs, stick applicators and cosmetic balls. One member predicted that cotton would replace rayon in more high tech areas because of a consumer-driven push and because of price.

Future Research: Coverstock, High Loft?

Proposed plans for continued research on cotton nonwovens were presented to the Task Force for comment. One member suggested that research be directed towards the evaluation of high cotton blends thermally bonded to produce lightweights fabrics, approximately 20 grams sq. meter. Properties suitable for coverstock weight should be investigated to meet the specifications required by industry, such as strikethrough, rewet and strength properties. Cross direction strength should be 150-250 grams an inch and a toughness index of 68.

However, it was pointed out that the diaper manufacturers are not very comfortable with new fabrics for coverstock and are reluctant to change. A member representing a manufacturer stated that they are currently producing a chemically bonded 100% cotton coverstock for feminine hygiene products, but added that it is unsuitable for diaper coverstock because it does not meet strikethrough and rewet specifications.

An extensive discussion followed concerning the merits of these properties. For example, the absorbent material located below the coverstock probably affects the speed of strikethrough to a much greater degree than does the fiber composition of the coverstock. Also, when total wear-time is considered, a diaper is unsoiled most of the time it is worn; when it becomes soiled it is usually changed. The question is, therefore, is it more important to have a coverstock that does not have excellent rewet properties or one that is more comfortable to the skin when it is dry? Babies cannot make this distinction and do not have a choice. Possibly a field trial evaluation of coverstock for adult incontinence products could answer these questions.

Some members of the Task Force thought that SRRC should not place too much emphasis on product-oriented research, that it should not concentrate its research on the narrow aspect of trying to improve a particular property of a specific product.

Concerning gray cotton, the consensus was that there was little or no interest in the market for gray cotton. (Gray cotton is bale cotton that has been mechanically cleaned but not wet finished). The problems is that gray cotton contains bacteria that causes byssinosis. Companies are not willing to install dust control equipment necessary to pass OSHA requirements to prevent byssinosis.

A member stated that fundamental research on nonwovens has declined. Research departments throughout the industry have been diminished. In this regard, he stated that SRRC should continue in the direction of the proposed areas of research.

He also suggested that we study an area that will bridge the gap between paper products and nonwovens. The Karl Kroyer process was specifically mentioned. A turnkey operation using the Karl Kroyer process for cotton fiber offers distinctive opportunities. Products 20 grams sq. meter and heavier could find utility as wipes, thick absorbents and hospital/medical materials.

One member suggested that cotton fiber has a sizable potential in high loft nonwovens. It was stated that 60 million pounds of high loft polyester are currently used in clothing insulation and furniture. Even if a small portion of this area could be penetrated by cotton, it would help to increase the utilization of cotton.

If cotton was blended with a low melting synthetic fiber for through-air thermal bonding, it would be necessary that cotton fiber be finished after bleaching to impart water repellency. However, the finish should not impair the processing of fiber into batts. Flame retardant finishing could also be investigated. Information is needed on the durability and dimensional stability of the high loft cotton nonwoven blends. Other methods of fabric formation could be investigated. Gray cotton, which is naturally water repellant, would be unsuitable because of the byssinosis problem.

In consideration of the equipment available, it was suggested that SRRC continue research on the evaluation of fabric properties of nonwovens containing cotton. For example, it is important to disseminate information on the biodegradability of cotton in relation to blends and synthetic fibers. Cotton fiber producers would like to research continue on biodegradability to show the advantages of cotton.

From the viewpoint of cotton producers, fiber finishing technology should receive top priority. Finishes are added for specific end uses of cotton fibers. Of utmost importance is a lubricant finish, which will increase production speed without loss of web quality. Finishes should not interfere with the final fabric properties; better yet, they should improve fabric properties.
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Author:Moreau, Jerry
Publication:Nonwovens Industry
Date:Feb 1, 1991
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