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The history of diaper elastic.

The History of Diaper Elastic

from the birth of an industry in the 1970s to the highly technical and complex products of the 1990s, diaper elastics have progressed along with the disposables industry; today's challenges are also its opportunities In the mid 1960s, the nonwovens industry introduced the first disposable diapers. A boon to parents, the disposable diaper was fashioned after the cloth diaper and contained no elastic. A decade later, legband elastic was added to the design of the disposable diaper, enhancing its containment properties and comfort. Thus, a new industry was born.

Through the past 15 years there has been a gradual evolution from the initial single and elastic manufactured for the first disposable diaper to the currently popular multistrand. Product development is being driven by manufacturers and designers of disposable diapers, each of whom have their own specific material preferences and methods of diaper construction. In turn, suppliers of diaper elastic must work closely with technical groups to produce a product that meets the desired specifications of the diaper manufacturer.

Introduction Of Diaper Elastic

In the mid 1970s, manufacturers of disposable baby diapers and adult incontinence products recognized a need for leg elastic to improve comfort and enhance the containment properties of their products.

Single end rubber tape was the first diaper elastic to be introduced, with a standard configuration of .007 inches thickness by 1/4 inch width (0.18 x 6.25 mm). As a forerunner of current diaper leg elastic tape, it was the first step in enhancing disposable diaper performance.

About six years later, bonded tapes in sizes .007 x 3/32 inch (0.18 x 2.38 mm) were developed. Bonded tape design consists of two or four ends of elastic that are slit and bonded back together into a single end tape by the diaper elastic supplier. The diaper manufacturer then splits the tape at the diaper machine as one or two ends are inserted into each leg of the diaper. Two ends per leg opening spread the holding power of the elastic over a wider area, reducing the chance of redlining on the infant's skin.

Several years later, new diaper innovations led to the development of multistrand rubber threads. Multistrand elastics contain six, eight or 10 ends that are bonded together and split by specially-designed splitters attached to high speed diaper machines as they are inserted into each diaper leg. Multistrand threads are designed to spread the compressive force of the elastic over a greater area, enhancing comfort. To compete with natural rubber multistrand, several companies began offering spandex, a fine synthetic filament consisting of multi fibers of spun polyurethane.

About the same time, polyurethane tapes were being developed. Polyurethane tapes are comprised of a man-made polymer that has superb elastic properties in sizes as thin as .001-.002 inches (25 to 50 microns). They offer excellent uniformity and talc-free processing in a single-end diaper tape.

The appearance and color of diaper elastics have taken on increased importance in the 1990s. Gender specific colors have been introduced by diaper elastic suppliers in order to keep pace with the rapidly changing requirements of the diaper manufacturer.

In summary, three types of diaper elastics--single end, bonded and multistrand in polyurethane, natural rubber and spandex--provide the diaper manufacturer with a variety of design choices. Each product holds a niche in the global disposable diaper industry, which total millions of dollars in annual sales. While multistrand rubber tapes have gained wide acceptance, there are some companies that prefer polyurethane or spandex synthetic elastics in their products. Single end and bonded diaper tapes are still the elastic of choice in some countries.

Evaluating Diaper Tape Performance

The cost of diaper elastic is nominal when compared to the total cost of a disposable diaper. However, diaper manufacturers spend much time and effort selecting the best elastic for their disposable diaper. Why? Because the proper diaper tape can mean the difference between smooth production line operation and good diaper performance versus costly machine downtime.

Diaper machines insert elastic tape into the legs of diapers typically at rates of up to 300 diapers a minute. Elastic tapes must be able to survive the rigors of insertion, which includes being stretched up to 300%, without tangles or breaks. Factors such as yield, elongation and elasticity are important considerations when selecting diaper tape.

For these reasons diaper manufacturers use several different methods to evaluate an elastic tape's performance. A common method used is the stress/strain curve. It illustrates the force required to stretch the elastic to a given elongation and also the force needed for the material to revert to its original length. (Figure 1 denotes the stress/strain curves for low modulus and high modulus natural rubber compounds).

How Diaper Tape Packaging Has Evolved

As the number and types of diaper tapes expanded, so too have new and improved methods of packaging the material. Initially, tangles and breaks were a serious problem. Often when the box was opened the rubber tape was tangled, preventing it from being pulled freely from the box onto high speed diaper equipment. A better packaging method had to be found to successfully dispense the material.

The festooning method of placing elastic in cartons allowed for tangle-free, rapid dispensing. This method worked so well that elastic suppliers were able to increase the amount of elastic packaged in each box from five-10 pounds to 40-50 pounds, enabling diaper manufacturers to run their equipment for longer periods with fewer changeovers.

As bonded and multistrand continue to evolve, diaper elastic equipment and packaging technology also continue to change. New machinery has been developed with precise slitting and bonding capabilities that can slit the elastic to very narrow widths. Spandex, a form of multistrand, presented special challenges in packaging because each single filament had to be wound onto a separate spool. It also presented a runnability challenge to the diaper manufacturer because of unequal lengths on each spool.

The Diaper Elastic Challenge

The impetus for new developments in diaper elastic will continue to come from the diaper manufacturers who introduce innovative diaper designs. Because there will always be a demand for uniqueness of product for special diaper applications such as the recent development of upstanding cuffs and elastic waistbands, there will continue to be a need for new diaper elastic materials and technology.

Environmental compliance will also play a large role in future diaper elastic development. Natural rubber products are biodegradable and will break down when buried in a landfill with exposure to microbial enriched soils. Natural rubber is also a renewable resource.

The diaper elastics industry is constantly evolving. Diaper elastic suppliers will continue to work closely with disposable diaper manufacturers on the development of new and improved designs and products. The ingenuity, creativity and cooperation of companies involved in nonwovens will drive the industry forward to meet the challenges of the future. [Figure 1 Omitted]

Goran Elovsson is director of sales and marketing, Diaper Elastic Div., Rubber Products Group, of JPS Elastomerics. Richard Zimmer is director of sales and marketing, Urethane Products Div., Extruded Products Group, JPS Elastomerics.
COPYRIGHT 1991 Rodman Publications, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991 Gale, Cengage Learning. All rights reserved.

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Title Annotation:technological advances in diaper elastics from 1970's to 1990's
Author:Elovsson, Goran; Zimmer, Dick
Publication:Nonwovens Industry
Date:Jun 1, 1991
Previous Article:Solvent spun cellulose fibers: an environmental perspective.
Next Article:Hot melts for nonwovens: the industry warms up to changes in the business.

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