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Unformatted text preview: Chapter 19- NONWOVEN FABRICS- 1 st nonwoven consumer product was an interlining fabric for apparel industry NONWOVENS DEFINED- Also fiber webs- Textile structure produced by bonding or interlocking of fibers, or both, accomplished by mechanical, chemical, thermal, or solvent means & combinations thereofASTM- Further: more than 50% by weight of nonwoven must be composed of fibers with an aspect ratio (length- to-diameter ratio) of 300; this excludes paper products that are normally made of extremely short fibers; in addition, nonwovens must have density less than 0.4 grams/cm 3- Most common categorization based on the method used to manufacture o Also classified as durable or disposable o Durabledesigned to be used multiple times o Disposabledisposed of after one use; some disposable not because they arent durable because of their purpose THE GLOBAL INDUSTRY- Starting materials range from wood pulp (by paper co.) to polymer pellets (resins; by lg. multinational chemical co.)- Nonwoven fabrics also called roll goods- Diff. segments of industry may be integrated o Ex: product manufacture can also produce its roll goods in-house MANUFACTURE- Two steps involved: 1) prep for fiber web & 2) bonding of fibers in the web- Fiber Web Formation o Staple Fiber Webs 1) Dry-forming Carding (also dry laying) OR air laying Carding: o Carded webs made in similar manner to process for slivers o Thin film of fibers removed from card laid onto conveyor (not drawn together into sliver) several carding machines working side by seed feed several thin fiber films to conveyor o Machine direction direction in which fiber are laid down o Cross direction perpendicular to machine direction Air laying: o Fiber opened suspended by air collected on moving screen 2) Wet-forming Similar to paper making Mixture of fibers in water collected on screen drained dried Wood pulp most common raw material used Staple-length manufactured used BUT more expensive & usually harder to disperse in water o Direct Extrusion Processes Fastest processes; one 3.5m nonwovens line will turn out approx. same amt of yardage as 3,000 57in. weaving machines operating @ 1000 ppm 1) Spunbonding Manufactured from synthetic filaments Polymer melted in an extruder melt pumped through rectangular spinneret w/1000s of holes (called a die ) upon exiting die, fibers enter chimney where turbulent air cools & entangles filaments then deposited in random pattern on moving belt vacuum under belt assist lay down of fibers passing spun-laid web through heated rolls to bond fibers completes process...
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- Fall '08