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Chemistry Is More Bio-Friendly

A new generation of dyes and pigments has arrived.

Beyond 2000: DyesandChemicalsBy Gary N. Mock, Technical Editor Chemistry Is More Bio-Friendly A new generation of dyes and pigments has arrived.The arrival of the new year was anxiously awaited by the computer-crazed world to see whether we would survive the Y2K glitches and bugs. In the textile chemical world, the good news about bugs was the arrival of more environmentally friendly enzyme bugs in product lines and more biodegradable auxiliary products being delivered to the waste stream. New dyes and pigments have arrived which are more stable on the one hand and contain biodegradable components at the same time. In some cases, less salt is discharged to waste streams; in other cases, lower emissions from tenter frames is the benefit. New chemistry will clearly be more bio-friendly. PreparationFor several years, Novo Nordisk has worked with universities to evaluate the further development of enzymes to lower reaction temperatures and replace caustic chemicals. In desizing, the use of amylases to remove starch from 100-percent cotton woven goods is the state of the art. Nolan Etters at the University of Georgia has evaluated alkaline pectinases to remove pectins from the primary cell wall of cotton. As a by-product, enough of the natural waxes are removed that wetting and wicking properties are sufficiently improved to allow excellent dyeing results.Dexter Chemical LLC markets the package as Bioscour 3000. Bioscour 3000 attacks the pectin interface between the cotton waxes and the cotton fiber, releasing waxes which are emulsified by surfactant chemistry. The recommended use level is 0.05- to 0.20-percent on weight of goods (o.w.g.), making the product cost-effective while allowing cotton strength to be retained.Full market whites are the goal of many knit finishers. The day-to-day variations in the water supplied by your local municipal water system can be nerve-wracking. Cibas Stabilon EZY® system significantly simplifies the hydrogen peroxide bleach process while maximizing whiteness, maintaining fiber protection and ensuring batch-to-batch reproducibility.  Dyes And Pigment SystemYes, systems. It is no longer sufficient to talk solely about a new dyestuff without discussing the auxiliary system that includes chemicals and control software and hardware. It takes a package to deliver the optimum results.Also new is DyStars idea of introducing electronic pattern cards. You are probably saying this is not new. What is new is the practicality now that color monitors and spectrophotometers can be tied together so closely that color renderings on the monitor are true to life. Now product information sheets are always up to date, so no expensive pattern cards are needed. Also possible is a search feature based on dye properties, fastness, application or equipment available.The system then identifies suitable dyes and trichromatic combinations. To simplify the search, the user defines the range of products. The pattern card will initially include reactive dyes and be expanded to other dye ranges. Disperse Dye DevelopmentsDisperse dye developments continue to follow the strong growth of PET polyester worldwide. This amazing polymer, Polyethylene terephthalate (PET), has been joined by a new polyester, polytrimethylene terephthalate (PTT), developed by Shell and licensed by KoSa, called Corterra® (See Quality Fabric Of The Month, ATI , August 1999). Corterra takes advantage of an economic breakthrough in the manufacture of one of the intermediate building blocks, propylene dioxide (PDO). The resilience of the new polymer will allow growth into more areas.NatureWorks PLA, another new fiber-forming polymer system under development by a joint venture between Cargill and Dow, is also disperse-dyeable (See Unique Fiber Breakthrough, ATI , March 2000).A new generation of disperse dyes is now available from DyStar. Dianix® ECO Liquid dyes incorporate a new dispersing agent system that has better dispersing action and is biodegradable.In the past, only a small proportion of the dispersing agent (approximately 25 percent) was biodegraded in aerobic waste-water treatment plants. The bulk was absorbed by the activated sludge and dumped in landfills along with the sludge. A new dispersing agent has more than 90-percent biodegradability by the end of the test period. Due to the efficiency of the new product, only one tenth as much agent is needed in the first place. Combine less product with increased biodegradability and you meet all the requirements of the okotex 100 specification.Dianix ECO Liquids can be applied in continuous and exhaust dyeing as well as textile printing. They are particularly suited for customers with automated liquid dispensing systems.Alkaline dyeing of polyester continues to progress. Dianix Black S-ER 300 percent and Navy S-ER 300 percent offer low cost, rapid dyebath exhaustion, leveling and build-up while meeting okotex 100 specification.  Reactive Dyes

Ciba has a new package of reactive dyes marketed under the CIBACRON® label. During the past decade, Ciba has been responsible for more than 40 percent of all European Union (EU) registrations of reactive dyes. Over that period, more than 72 new CIBACRON dyes, containing one or more of the patented, registered dye molecules, were launched. These are CIBACRON C for pad-batch and continuous dyeing of cellulose and blends; FN for warm exhaust on wool, nylon and acrylics on jets; W for specialty dark shades; LS for low-salt dyeing; H for hot exhaust dyeing; and P for printing.In particular, replacements for Reactive Black 5, the workhorse reactive, are CIBACRON Navy C-B and Navy FN-B. These have better wash fastness and are not as affected by the new home laundry products which attack Black 5. CIBACRON Red C-2BL and Red FN-2BL give higher lightfastness than traditional reds and are metal-free.DyStar has introduced additional reactive dyes (a scarlet and an orange) to the Levafix® CA product range introduced in late 1999. CA (Combined Anchor) refers to the use of chlorine-free tri-fluoropyrimidine, mono-fluorotriazine and new vinyl sulphone anchor groups. Levafix Red CA, Yellow CA, Blue CA and Navy CA exhaust on tone and give fixation in the 90+ percent range. These are suitable for all reactive dyeing processes. In exhaust dyeing, they can be applied between 140° and 180°F.All dyes have excellent wet fastness and wash-off properties. But what happens to the hydrolyzed dye released in the wash water DyStar has begun marketing with Bayer AG, Baysolex VP SP 20019/20020, for the aftertreatment of reactive dyeings. Bayer developed an enzyme system with Novo Nordisk that destroys reactive dye hydrolysate in the washing liquor without having any significant impact on dyes already fixed on the fiber. The system cuts the number of wash-off baths required or the volume of water needed in a continuous overflow rinse, leading to substantial savings in time and water. PrintingCiba and DyStar have been active in supplying printing inks to developers of the ink-jet textile printing projects. Ciba has worked with Stork, and DyStar has worked with Zimmer.New products include Ciba TERASIL® DI 100-800 range of water-dispersible inks for polyester garments and automotive fabrics; LANASET® water-soluble acid inks for wool, silk and polyamide fabrics; CIBACRON reactive inks for cellulose and IRGAPHOR® TBI pigment inks for all substrates.Drop-on-demand piezo and bubble-jet technologies are leading the way to the establishment of rapid prototyping apparel projects at North Carolina State University under the direction of Professors Istook and Donaldson.Full production printing is just around the corner. While slow at printing per square yard, these technologies can be used to print garment panels without the waste of printing the unwanted fabric around the panel and are ideal for short-run print-on-demand needs. Designers can go from CAD design to printing and cutting and sewing to see new designs realized in a matter of minutes. FinishingCiba has released Zonyl® 9200, a new fabric protector system that can be applied with durable press finishes. The aqueous fluorochemical dispersion imparts stain repellency and stain release while maintaining breathability. Application can be made from pad-batch, vacuum, spray and foam and in garment finishing.Bayer has incorporated polyurethane wetting agents to develop low emission fluorocarbon finishes. Tenter exhausts are cleaner than ever. Polyurethane improves the hand of finished garments and also has been proven to prevent indigo backstaining during subsequent laundering. Beyond 2000The chemistry discussed so far is available today in commercial quantities. What about the near futureNew Polylactic Acid (PLA) Polymers are being commercialized by Cargill Dow Polymers LLC. A recent advance in the fermentation of dextrose from corn dramatically reduced the cost to manufacture the lactic acid monomer necessary to make PLA polymers.A 14-million-pound/year pilot plant has been furnishing polymer to potential customers in targeted applications such as carpet, yarn and nonwovens. A 300-million-pound/year plant is scheduled to be operational by early 2002.The good news is a fiber that comes from renewable resources is more hydrophilic than polyester, has excellent hand and drape, has good resilience, is unaffected by UV yet composts at 60°C and 90-percent RH and degrades to CO2 and water.One billion pounds of PLA is equivalent to 0.5 percent of the annual U.S. corn crop. Since only 75 percent of the available acreage is presently used and corn is the cheapest source of dextrose, monomer supply is more than adequate to meet demand in the foreseeable future. CyclodextrinsCyclodextrins (CDs) are currently under investigation as inclusion compounds for a number of textile applications. As the 6-, 7- and 8-membered rings are clipped from starch by an enzyme system, they form a truncated conical cylinder with a hydrophobic core and a hydrophilic exterior.Monochlorotriazine groups tagged onto the CD by Wacker Biochem Corp. give reactivity with cellulose. Figure 1 shows a cyclodextrin and two reactive groups attached to cellulose molecules. Trace amounts of chemicals such as perfume secluded in the core can be released during wearing of the garment. During a laundry operation, chemicals can be scoured from the wash water and sequestered.The individual CDs can self-assemble into a stacked arrangement or form a brick or herringbone pattern. The stacked arrangement has enabled researchers to straighten linear polymers and align them side by side like stacked uncooked spaghetti. Previously incompatible polymer mixtures can now be made compatible by including CDs. This field is just beginning to grow.Phase Change Materials have been a pet project for David Colvin of Triangle Research and Development Corp. for a number of years. These products are finally finding their way as microencapsulates and macroencapsulates into protective garments for firefighters.An April 2000 Conference on Safety and Protective Fabrics, sponsored by the Industrial Fabrics Association International, included a talk on the status of these interesting compounds. The particles increase fiber thermal capacity or heat storage properties by up to 1,000 percent. Fibers and foams with microencapsulates can be warmer, thinner, lighter or less bulky and more comfortable than conventional apparel.The future is bright with interesting new products. Try them; I think you will like the results.

June 2000



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