Binder fibers

Binder, fibers, fillers, abrasives, lubricants, additives, surface topography, shape, size, mechanical, chemical, and thermal properties... 

The polyester fibers have high shrink properties, which make them useful in fiber applications where crimp retention or high bulk is desired. Typical applications are in carpet yams, hi-loft non-woven fabrics used as interlinings, cushioning media, and filtration media, as well as in specialty yams for weaving and knitting. The fibers have a lower melting temperature compared to PET, which makes them useful as binder fibers in non-wovens, particularly in combination with PET homopolymer fibers. 

Disposable absorbent articles generally contain absorbent fibrous webs, such as airlaid or bonded carded webs. Such webs are often stabilized with binder fibers during web formation. 

These binder fibers are multicomponent fibers with a significant difference in their melt temperature. The fibers are heated at a temperature sufficient to melt the lower melting components, but not the higher melting components (25). 

Several binder fibers have been developed that are biodegradable to enhance the disposability of the absorbent article. Most often, biodegradable polymers are formed from aliphatic polyester materials. A multicomponent fiber that contains a high melting aliphatic polyester and a low-melting aliphatic polyester has been developed (25). 

Binder fibers n. Fibers that can act as an adhesive in a web because their softening point is relatively low compared with that of the other fibers in the material. 

Bonding with binder fibers n. Specially engineered low-melting point fibers are blended with other fibers in a web, so that a uniformly bonded structure can be generated at low temperature by fusion of the binder fiber with adjacent fibers. Skeist I (ed) (1990) Handbook of adhesives. Van Nostrand Reinhold, New York. 

Thermobonding n. A technique for bonding fibers of a web with meltable powders or fibers, using infrared heating, hot air, or hot-calendaring also see bonding, bonding with binder fibers, and powder bonded non-woven). 

Fiber type adhesives. Between 5 0% by weight of these fibers is mixed in with the base fibers. The web is then hot-calendered to cause the bond to form. The binder fibers must have a lower melting than the fibers in the web, and are softened or melted by the hot-calendering process, causing the bond to form. 

The elastic modulus of the swollen superabsorbent polymer is important for several reasons. The powdered polymer is typically used in a physical blend with fibers such as cellulose and thermoplastic binder fibers. The resulting structure is called the absorbent core. The absorbent core relies on pore spaces between the fibers and polymer particles to provide liquid transport volume for the overall structure. When the swollen superabsorbent particles have low modulus, they are easily deformed by body pressures and can fill in the interfiber and interparticle pores. This prevents liquid flow and wicking of liquid into the drier portions of the core. Higher modulus limits the deformation of the particles and helps maintain the pore space. 

FIGURE 29.1 Cross-sectional view of sheath/core type of PLA bicomponent fiber and thermal bonding nonwoven made from the sheath/core type of fibers as binder fibers. 

In the technology development area PLA/PLA binder fibers are finding application in mattresses, and other bonded batting areas. 

Overall, PLA binder fibers can replace existing synthetic polymers where renewable resource is a benefit or where additional performance such as controlled temperature bonding, controlled shrinkage or lower temperature processing is required. In addition, improved or reduced adhesion and alternative approaches to soluble/non-soluble island/sea combinations are all possible and under development. 

Research on cotton-based nonwovens has been carried out at the University of Tennessee since 1987 by applying different kinds of binder fibers through... 

Five different kinds of fibers were used for the study. Cotton fiber is the base fiber, and four types of binder fibers, ordinary cellulose acetate (OCA), plasticized cellulose acetate (PCA), Eastar Bio copolyester unicomponent (Eastar), and Eastar Bio copolyester bicomponent (Eastar/PP) fibers. The chemical name of Eastar Bio copolyester is poly(tetramethylene adipate-co-terephthalate) (PTAT). The cotton fiber used in this research as the carrier fiber was supplied by Cotton Incorporated, Cary, NC. The scoured and bleached commodity cotton fiber had a moisture content of 5.2%, a micronaire value of 5.4 and an upper-half-mean fiber length of 24.4 mm. Both the OCA and PCA binder fibers were provided by Celanese Corporation, Charlotte, NC while the Eastar and Eastar/PP bicomponent binder fibers selected for this study were produced by Eastman Chemical Company, Kingsport, TN. The plasticizer used in PCA binder fiber is triethyl citrate ester (C12H20O7) with a weight concentration around 2%. The bicomponent Eastar/PP has a sheath core structure with Eastar as the sheath and PP as the core. The properties of these selected fibers are listed in Table 10.3. 

The nonwoven fabrics in this research were produced by first carding of cotton and the binder fiber and then thermally bonding the carded webs. The fiber components were prepared by separately opening and then hand mixing of the two fiber types for homogeneity. The fiber blend was then carded to form a web using a modified Hollingsworth card with the conventional flats... 

The desired calendering temperature of PCA bonded nonwovens is still much higher for achieving good tensile properties. So, a newly introduced biodegradable copolyester unicomponent (Eastar) fiber, which has a relatively low softening temperature ( 80°C), was further selected as a binder fiber instead of cellulose acetate fiber. It has been reported that this binder fiber... 

Flexural rigidity and absorption properties of the cotton/(Eastar/PP) nonwovens were also studied. Results show that the nonwovens have good flexural rigidity and absorbency, which indicate that the nonwoven materials may be used for medical and sanitary applications. However, one has to remember that PP component in the bicomponent fiber is not biodegradable this puts this fabric in the category of many other cotton/binder nonwovens that may have PP or PET as binder fibers. The results obtained from these... 

Haile, W.A., Tincher, M.E. and Williams, F.W., A Biodegradable Copolyester for Binder Fibers in Nonwovens , Proceedings of Insight 2001 International Conference, 2001. 

In recent years, PO thermoplastic fibers have been used both in homocomponents and heterocomponents [99, 588-668], as bonding agents in the production of nonwovens. There are many reasons for this interest in thermal bonding the economics of adhesive bonding, the production of novel thermally bonded structures through the use of bicomponent fibers, and the introduction of new or improved fiber types specifically designed for use as binder fibers. 

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