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Hospital/medical applications: for polyolefin nonwoven products.

HOSPITAL/MEDICAL APPLICATIONS For Polyolefin Nonwoven Products

Costs for health care in the U.S. represent about 11% of the gross national product. In spite of cost containment efforts by the federal government and more recently by industry, medical costs continue to increase. By the year 2000, expenditures for medical care in the U.S. are expected to almost triple from their present levels.

Although supplies represent only 15-20% of hospital costs, efforts to contain costs in hospitals have resulted in pressures on the suppliers of materials used by hospital and medical facilities. Hospitals are now being run by administrative professionals rather than by doctors. This has resulted in more group buying units being formed by hospitals and clinics.

It appeared that the trend towards the use of more disposables was slowing. However, the AIDS epidemic has changed this situation. In most cases, the trend for hospitals to use more disposables can be justified, but it's important for the suppliers of these products to be able to prove this to the hospital purchasing groups for new products. There are good growth opportunities for developing specialty hospital/medical products at affordable prices.

Hospital/Medical Gowns

The basic functions of apparel worn in the operating room are to help preserve a clean environment, reduce the number of airborne microorganisms, help preserve sterile or aseptic operating room techniques, protect surgical personnel from pathogens originating from the patient and protect the patient from bacterial transmissions from surgical personnel.

Since untreated cotton operating garments have been found to contribute to higher particle counts in the operating room and not provide an effective sterile barrier between the surgical personnel and the patient, they are rapidly disappearing. One of the major attributes of the cotton operating gown, however, was that it was very comfortable to wear.

One of the techniques used to improve the comfort of operating gowns is to use a barrier-type for the front half of the gown and to use a more breathable fabric for the back. The AIDS epidemic has resulted in a need for more effective gowns, lab coats, coveralls, aprons and other medical garments for the protection of hospital and medical laboratory personnel.

Kimberly-Clark's Professional Health Care Div. has developed a line of clothing products called the "Control Cover" line made of its three layer spunbonded/melt blown/spunbonded composite fabrics. K-C has devised a series of tests to measure blood strikethrough for gowns. Control Cover showed only a 1.4% strikethrough compared to ranges from 68.6% to 82.9% for other gowns. Other lines of gowns sold by K-C are its "Spuncare" and "Evolution" brands.

Spunlaced fabrics based on polyester/pulp combinations and composites of spunbonded polypropylene/melt blown polypropylene/spunbonded polypropylene are two of the major fabrics used in disposable surgical gown and drape applications.

Baxter Healthcare Products is using DuPont's "Sontara" polyester/pulp fabrics in its surgical gowns and drapes. The Surgikos Div. of Johnson & Johnson is reported to be switching some of its surgical gown and drape line from the Sontara fabric to a polypropylene composite fabric.

K-C has been placing major emphasis on the safety of its spunbonded/melt blown composite fabrics in the operating room when carrying out laser surgery. K-C's fabrics are the only fabrics currently meeting a Class I (relatively slow burining) rating for laser surgery.

Wet laid nonwoven products have found a large number of applications in the hospital/medical field. Dexter Nonwovens has its "Stasis" line of polycoated fabrics. Included in this line are splash mask coverstock, polycoated emergency drape/sheets, polycoated yellow and blue colored fabrics for shoe covers, lab coats, emergency drapes, cover gowns and face masks.

O.O. Concepts, Roanoke, TX, has introduced a specialized thermal draping material called "Thermadrape." The tissue/metallized film laminate controls radiant heat loss from the patient, which is responsible for about 50% of the heat a patient loses during an operation.

Other Medical Product Areas

The old fashioned gauze mask with its 50% or less efficiency has been superceded by nonwoven masks that provide efficiencies as high as 98%. The emphasis in the use of face masks has changed. In the past the prime concern in using face masks by hospital personnel was in protecting the patient. This is still important, but with the outbreak of AIDS there is equal concern in the use of disposable masks to protect hospital personnel. Melt blown microfiber filter media is displacing much of the microglass media that had been used for surgical face masks. Dexter's Stasis and K-C's Control lines meet these needs.

Baxter Hospital Supply is distributing a variety of surgical masks produced by Tecnol, Fort Worth, TX.

The surgical wrap market is about a $70 million market in the U.S. K-C is estimated to have about a 50% share of a market that is about 60% penetrated by nonwovens.

James River recently began to sell a 100% polypropylene sterilization wrap made of a spunbonded melt blown laminate. The product is called "Caretex" sterilization wrap. System One is used to wrap a gown for sterilization and System Four is used to wrap an instrument tray. Each weight of surgical wrap is color coded.

K-C is marketing its "Kimguard" surgical wrap with a 60 day shelf life. James River's Caretex is promoted with a 180 day shelf life.

Cotton guaze is still used extensively as a wound dressing. However, spunlaced products are starting to make some headway. J&J is selling wound care products based on spunlaced technology under its "Nu-Gauze" dressing label; J&J still markets a large number of products based on woven cotton guaze.

Kendall Healthcare Products, Mansfield, MA, is marketing "Tendersorb" abdominal pad products that use a thermally bonded nonwoven produced by Veratec. Beirsdorf, Norwalk, CT, is marketing a spunlaced nonwoven fabric in its "Cover-Roll" stretch adhesive bandage product line. Lohmann, Tulsa, OK, markets an adhesive bandage product using an apertured nonwoven in its "Selofix" line. In France, Smith & Nephew uses DuPont's Sontara in a new non-allergenic wound dressing. Applied Extrusion Technologies' "Delnet" has been used for a number of years in J&J's "Band Aids." Aso Pharmaceutical, of Japan, which has a U.S. plant in Lakeland, FL, uses Sontara and an 80% rayon/20% polypropylene thermal bonded fabric.

Baxter Healthcare is marketing its "DuoThermal Hypo/Hypothermia" blanket, which uses a blanket covered with a nonwoven on each side. One side is absorbent and the other has a repellent treatment. The nonwoven fabrics incorporate melt blown material.

Gamma Ray Sterilization

And PP Nonwovens

There are three basic methods of sterilizing products for use in hospital/medical applications: steam sterilization, ethylene oxide sterilization and gamma ray sterilization. The third method - gamma ray sterilization - is becoming more popular.

The gamma ray sterilization process has many advantages over the other systems in terms of thoroughness of treatment. There are, however, some problems with the effect of gamma rays on some materials. Cellulosic materials experience some degradation and produce some odors. High density polyethylene loses some strength. Polypropylene, nylon and polyvinyl chloride undergo some degradation. Polypropylene also discolors. Polyester fibers and acrylic binders are unaffected by the gamma rays.

In order to compensate for polymer degradation in polypropylene, higher levels of phenolic antioxidants are added. The higher levels of hindered phenois, however, lead to the development of yellow color during storage. The discoloration is a reversible reaction and develops upon storage in the dark. The chemical mechanism for this discoloration is not fully understood.

Recent work by Ciba-Geigy, however, indicates that some oligomeric hindered amine stabilizers (HALS) can be used to replace some of the hindered phenols and perform as heat and gamma radiation stabilizers. Several of the polypropylene manufacturers are formulating these HALS into specialty grades of polypropylene that have improved resistance to gamma ray sterilization.

Even though selected stabilizers improve the gamma ray resistance of polypropylene, they do not eliminate the problem to odor completely. Exxon is currently evaluating copolymers of polypropylene with other materials to try to improve the gamma ray resistance of polymers for melt blowing and other fiber applications.

Another approach is to use linear low density polyethylene in applications for gamma ray sterilization. The LLDPE material has better resistance to this form of sterilization than polypropylene.

Nonwovens In Sponges

Nonwovens were first used in sterile dressings, eye pads and sponges in the late 1960's. The carded and resin bonded nonwovens at that time were not used alone but in combination with absorbent fillers such as a cotton and cellulose absorbent tissue. The nonwovens had sufficient tensile strength to be used as covers for the weaker absorbent tissue.

The wet tensile strength and wet bursting strength of the early carded and resin bonded nonwovens were too low for use as laparotomy sponges, which may be subjected to significant mechanical stress during operations. The nonwoven sponges were too smooth for use in scrubbing or scouring dirty wounds in preparing for surgery.

The incorporation of polypropylene and linear low density polyethylene fibers in blends with cotton, rayon and wood pulp in hydroentangled nonwovens is under development by several nonwovens producers. The polyolefin fiber producers need to determine the modifications that are needed to their fibers in terms of type of elongation, modulus, crimp level, type of crimp and cross section to optimize performance in the hydroentangling process.

The two fastest growing technologies over the next five to six years will be spunlaced and melt blown, followed by spunbonded. Wet laid nonwovens may lose some market share to spunlaced; however, some of the spunlaced producers will be using modified wet laid processes as well.

The major loss in market share will occur in the dry laid process. The more technologically adept dry laid producers may be able to protect their market position by using their fabrics as composites with other types of nonwovens, such as spunbonded, melt blown or extruded nettings and with specialty films or coatings.

Outlook For Medical Materials

The total market for fabrics for hospital/medical applications is estimated at about 3.3 billion sq. yards. This includes items such as sheets and pillow cases. Nonwovens have about 60% penetration of the hospital/medical market, equal to about two billion sq. yards.

There remains intense competition between nonwoven technologies for products in the hospital/medical market and there is a great degree of interchangeability between types of products made by different methods in some applications. An estimated percentage of different types of nonwovens used for hospital/medical applications is included in Table 1.
 Table : Table 1
 (By Fabric Type - 1988)
Process Type MM Sq. Yards % of Total Use
Spunbonded 400 20
Spunlaced 340 17
Dry Laid 440 22
Wet Laid 500 25

Melt Blown & Melt Blown
Composites 260 13
Other(*) 60 3
Total 2000

(*) Includes extruded nettings, needlepunched and stichbonded fabrics.

In the fiber area (Table 2), rayon will lose market share because of its price relative to other fibers. Cotton and wood fibers should be able to increase their market share because of their increased use in the spunlaced process.

Polyester will lose market share to polypropylene because of polypropylene's more stable price and price advantage. However, after 1995, polyester may become more price competitive as several new products enter the market in the U.S.
 Table : Table 2
 1988 1995
 MM Lbs. % MM Lbs. %
Cellulosic Fibers(*) 50 47
Polyester 23 18
Polypropylene 25 40
Polyethylene 2 10

(*) Cellulose fibers include rayon, cotton and wood pulp (**) Includes HDPE in Tyvek and extruded nettings and LLDPE fiber
COPYRIGHT 1989 Rodman Publications, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1989 Gale, Cengage Learning. All rights reserved.

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Publication:Nonwovens Industry
Date:Nov 1, 1989
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