Diaper elastics

The elastic nonwoven possesses unique properties useful to applications such as inexpensive elastic leg cuffs and waistbands for disposable diapers. Elastic CCN has the advantages associated with stretchability, but also has further improved wicking properties compared to CCN before heat stretching, due to the greater machine direction orientation of the cotton and PP fibres, making them ideal for feminine hygiene pads and diapers (Christin, Dong, Lary, 2002). 

The primary non-woven applications for hot melts are in disposable articles such as diapers and sanitary napkins (see Fig. 22). These articles are made by high speed processes and are immediately packaged in sealed plastic bags, thus they are prime candidates for hot melt use. The applications are broken down into three categories, requiring three different types of adhesives construction, elastic attachment, and garment attachment. 

Lower-density E-plastomers have found alternate use in cast film processes to make elastic film laminates with good breathability which contain laminates of liquid impermeable extensible polymeric films with extensible-thermoplastic-polymer-fiber nonwovens and nonwoven webs of polyethylene-elastomer fibers as the intermediate layers. The development relates to a breathable film including an E-plastomer and filler that contributes to pore formation after fabrication and distension of the film. The method and extent of distension is designed to produce a breathable film by stretching the film to form micropores by separation of the film of the E-plastomer from the particulate solids. This film is useful for manufacture of absorbent personal-care articles, such as disposable diapers and sanitary napkins and medical garments. In detail, these constructions comprise a liquid impermeable extensible film comprising polyolefins. The outer layer contains extensible-thermoplastic-polymer-fiber nonwovens, and an elastic intermediate layer contains nonwoven webs of fiber E-plastomers. The intermediate layer is bonded to the film layer and the outer... 

Anionic polymerization of polystyrene takes place very rapidly- much faster than free radical polymerization. When practiced on a large scale, this gives rise to heat transfer problems and limits its commercial practice to special cases, such as block copolymerization by living reactions. We employ anionic polymerization to make tri-block copolymer rubbers such as polystyrene-polybutadiene-polystyrene. This type of synthetic rubber is widely used in the handles of power tools, the soft grips of pens, and the elastic side panels of disposable diapers. 

Another widespread use of polyurethane elastic fibers is in disposable diapers and adult incontinence garments. Elastic strands are incorporated into waistbands and side panels made of non-woven fabrics where they improve fit and reduce leakage. 

Disposables are also considered to be an environmental threat. Only some of the materials used in the diapers are biodegradable (the wood pulp and SAP). The polyethylene and polyester sheets are not biodegradable neither is the elastic used for better fit, nor the polypropylene used for the tape that is employed as a fastener. Disposable diapers account for up to 2 percent of the total volume of landfills in the United States. The lifetime of the diaper in the landfill depends on several environmental factors soil condition, groundwater flow, and the presence of other materials in the soil. see also Matertals Science Polymers, Synthetic. 

Consider the disposable diaper. The outer, waterproof layer is composed of polyethylene. The polymeri2ation reaction that produces polyethylene is shown in Section 12.4. The diapers have elastic to prevent leaking. The elastic is made of a natural polymer, rubber. The monomer from which natural rubber is formed is 2-methyl-l,3-butadiene. The common name of this monomer is isoprene. As we will see in coming chapters, iso-prene is an important monomer in the synthesis of many natural polymers. 

Latex products are derived from a liquid that comes from rubber trees (natural rubber). Latex is widely used in today s modern world—elastic bands in clothing and undergarments, latex or rubber gloves, balloons, baby bottle nipples, rubber bands, toys, condoms, bandages and tapes, and disposable diapers and other products. 

According to a diaper market sustainability report issued by EDANA, Brussels, Belgium, the average baby diaper is comprised 43% of fluff pulp, 27% SAP, 15% PP, 7% PE, 3% adhesives, and 1% elastics (Edana, 2008). The nonwoven fabric required is of 20—25 g (Pancholi Naik, 2008). Disposable baby diapers were first introduced in the early 1960s, and since then, have been marked by continuous product innovations, including the addition of SAP, resealable tapes, and elasticized waistbands. 

In general two types of adhesives are used for the manufacture of baby diapers, feminine-hygiene, and incontinence products. For simple construction purposes, hot-melt adhesives based on amorphous poly(alpha-olefins) (APAOs) are used. High-quality constructions are produced with adhesives based on styrenic block copolymers. For bonding of elastic materials such as polyurethane foam, lycra and natural rubber strands, and hydrophilic and hydrophobic of nonwovens, pressure-sensitive adhesives (PSAs) based on styrenic block copolymers are used. Hot-melt adhesives are the most common types of adhesive. The most widely used synthetic block copolymers are styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), and styrene-ethylene-butadiene-styrene (SEES) with different styrene contents. 

Determined explorer stage In this stage babies have become able to walk and are very mobile, so it is important that this mobility is not inhibited by diapers. Diapers for babies in this stage feature not only good absorbency but also elastic elanents such as stretch sides to adapt to the baby s body during movanent, and are made especially thin and narrow between the legs for a good and comfortable fit. 

Kataoka, T. Pol5mrethane elastic fiber roll containing hydrophobic dyes for disposable diapers. Jpn. Kokai Tokkyo Koho JP 2005154909, 2005 Chem. Abstr. 2005, 143, 65549. 

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