Nonwovens Technology
By Richard G. Mansfield,Technical EditorWater TricksThe use of directed water jets to produce
nonwoven fabrics has accelerated with the continued development of spunlacing technologies and
hydroenhancement finishing techniques.
Rieter Perfojet’s spunlace installationThere are two major applications for the use of
directed water jets in textiles. The first system was commercialized about 30 years ago for
producing spunlaced nonwoven fabrics. During the past 10 years, the production of spunlaced fabrics
has accelerated throughout the world as their use in consumer products and industrial and medical
uses continues to grow.The second major application for directed water jets is hydroenhancement for
fabric finishing. Hydroenhancement of fabrics can be most effective when the choice of yarns and
the fabric structure are modified to optimize the beneficial effects of hydroenhancement.Spunlaced
NonwovensSpunlaced nonwovens are made by the entanglement of a fibrous web by fluid means. Fluid
entanglement provides strength and integrity to the fibrous web. Spunlaced nonwovens produced
commercially now are made by water entanglement techniques.The term hydroentangling also is used to
describe processes for making spunlaced fabrics. When the fluid entanglement is done with patterned
screens, a design element can be built into the fabric. Spunlaced fabrics can be made to have
drapability and hand equal to those of woven or knit fabrics.The basic elements of the systems used
for making spunlaced fabrics are:• a web-forming system — usually a modified carding system — used
on spunlaced fabrics with the exception of nonwovens made from hydroentangled long-staple wet-laid
nonwoven webs;• high-pressure water-jet injectors or manifolds with typical pressures ranging from
5 to 250 bars;• dewatering or vacuum boxes;• filtration and water recovery units;• patterning or
perforating units, which can be a patterned wire drum unit or a patterned conveying screen system;•
drying unit; and• wind-up unit.The principle of hydraulic entangling systems is to project
high-velocity water jets onto a supported nonwoven web. The shape and disposition of the holes in
the patterning drum or screen control the pattern of the spunlaced fabric.Early DevelopmentOne of
the earliest applications for fluid entanglement of nonwovens was realized by Chicopee, a former
division of U.S.-based Johnson & Johnson (J&J), which used it to make apertured fabrics for
household wipes.Some of U.S.-based DuPont’s early work with spunlaced fabrics was related to its
Corfam® poromeric man-made leather work dating back to the late 1950s and early 1960s.
Spunlaced-type products were evaluated as possible replacements for the expensive woven
reinforcement fabric in Corfam. After DuPont discontinued the Corfam program, hydroentangling work
was continued at DuPont’s Christiana Laboratories. Although Chicopee can be considered the first
company to use hydroentangling for nonwovens, DuPont was the first company to introduce more
sophisticated fabrics using hydroentangling technology.It is questionable whether DuPont would have
continued its development work with spunlaced products if U.S.-based Burlington Industries had not
entered the picture in about 1968. At that time, Burlington’s research and development group was
investigating potential uses for nonwovens in the company’s products.Early in 1969, Burlington
established a cooperative research and development program with DuPont to evaluate using spunlaced
products within all of its appropriate divisions. Some of the initial product areas that Burlington
investigated included bonding substrates for woolens, warp and circular knits and drapery
fabrics.As the cooperative program progressed, Burlington’s research and development group
recommended in 1971 that the company establish a nonwovens converting and finishing plant to
process the spunlaced fabrics. This processing operation was transferred to Burlington’s New
Business Ventures Group. The spunlace converting operation initially operated by the Burlington New
Business Ventures Group was later incorporated into the Burlington Formed Fabrics Division.At
first, Burlington was the only processor of DuPont’s spunlaced fabrics, but DuPont later broadened
distribution of the product to include other processors. In the mid-1980s, when Burlington was
restructured, the Formed Fabrics Division and the nonwovens converting and processing operations
were sold to some of its former managers and now operate as part of U.S.-based Precision Fabrics
Group Inc.
The majority of wipes products are made with spunlaced nonwovens.Activities At Chicopee
J&JDuPont developed a line of spunlaced fabrics using 100-percent cellulosic materials, which
were sold to J&J for use in surgical packs. J&J recognized the potential for spunlaced
nonwovens to replace woven gauze fabrics for hospital/medical uses, which led Chicopee to
accelerate work on its hydroentangling technology for making spunlaced fabrics under its Duralace®
trade name.By the end of 1976, Chicopee had evaluated rayon, wood fibers, polyester, cotton,
polypropylene and combinations of these fibers in a range of spunlaced weights and patterns. The
fabrics were produced from modified card-fed air-laid units, relying solely on water entanglement
for bonding.For many years, nonwovens technology was very proprietary and was the domain of only a
few companies. As many of the early patents expired and more companies entered the nonwovens
business, technical personnel could move more freely from one company to another. Chicopee’s
advantage as an internal nonwovens supplier began to diminish. Products that once were available
only from Chicopee now became available from other suppliers at lower cost.
Spunlaced Fabric End UsesOne of the early objectives for spunlaced fabrics was to use them to
replace woven gauze in products such as laparotomy and X-ray-detectable sponges. These efforts have
been successful, and spunlaced products have gained wide acceptance in these products, as well as
in surgical gowns, drapes and scrub suits.Surface veiling for fiberglass-reinforced plastics (FRP)
was one of the earliest uses found for Sontara fabrics. The spunlaced polyester enables the FRP
producer to use the increased toughness and resilience of the new higher-elongation
corrosionresistant resins. The tensile elongation properties of the polyester spunlaced veilings
are more compatible with the resin properties and conform more readily to the contoured surfaces of
the structures. Polyester spunlaced fabrics also find uses as carrier webs in pultrusion products
and for use in making filament-wound pipe.DuPont makes Sontara products from its Nomex® fiber for
heat-shielding applications. Sontara products also are made from Kevlar® fabrics for aerospace
uses.A trip to the supermarket reveals a myriad of wipe products — the majority of them using
nonwoven fabrics, particularly spunlaced nonwovens.
DuPont™ Nomex® fibers provide good heat-shield properties that are essential in products such
as firefighters’ protective gear.Freudenberg’s Evolon® ProductsEvolon®, produced by Freudenberg
Nonwovens Group, Germany, combines modified spunbond and hydroentangling technologies to produce
structures comprised of microfilaments. The spunbond technology produces multicomponent fibers that
split into microfilaments by the action of the water jets in the hydroentangling unit. The
following advantages are claimed for Evolon products:• lightweight fabrics with good hand and
drapability;• multi-directional high-tensilestrength fabrics with high tear strength; and• the
ability to make fabrics that are either hydrophilic or hydrophobic.The Perfojet SystemThe Perfojet
Co. was founded in France in 1984 by nonwovens innovator André Vuillaume. Under his direction, its
first spunlace production unit was installed in 1985. The company was acquired by the ICBT Group in
1991 and renamed ICBT Perfojet. In 1996, the first Jetlace 2000 system was in operation. The
Jetlace 2000 system uses multi-sided hydroentanglement, which provides energy-savings and enhanced
fabric characteristics at web weights ranging from 20 to 400 grams per square meter (g/m2), at
speeds up to 300 meters per minute. In 2000, Switzerland- based Rieter Group finalized its
acquisition of ICBT Perfojet, renaming the company Rieter Perfojet.The latest spunlacing product
developed by Rieter Perfojet, is the Jetlace 3000 system, which optimizes energy use via new
injectors linked with a special strip design. The Jetlace 3000 is used to fabricate wet wipes in a
three-step procedure: entanglement of the fibers; insertion of pulp into the entangled web; and
entanglement of the pulp into the web.Rieter Perfojet has also integrated its Perfobond spunbond
technology with its Jetlace 3000 system. This technique produces fabrics that combine the virtues
of filament yarns and staple fiber yarns.Today, there are more than 100 Rieter Perfojet
hydroentangling lines installed throughout the world.Fleissner’s AquaJetGermany-based Fleissner
GmbH introduced its AquaJet spunlace lines in the 1990s. This product line encompasses:• AquaJet
for entangling of lightweight nonwovens up to 150 g/m2, and heavyweight nonwovens up to 600 g/m2;•
AquaSpun for entangling of spunbonded webs;• AquaSplit for entangling and splitting of microfiber
webs;• AquaPulp for entangling and bonding of nonwovens with a pulp layer; and• AquaTex for
enhancement of woven fabrics using U.S.-based Polymer Group Inc.’s InterSpun technology.
Fleissner’s AquaTex features InterSpun technology from Polymer Group Inc.Fabric
HydroenhancementAlthough spunlaced nonwoven fabrics have been available for more than 30 years, the
related processes to finish fabrics using water jets (hydroenhancement) have gained commercial
acceptance only over the past five years. The basic spunlace technology used to produce nonwovens
does not vary substantially from fabric enhancement technology, but rather varies in degree.An
important contributor to the development of fabric hydroenhancement is Gerold Fleissner of
Fleissner GmbH. Fleissner and his associates have been issued a number of U.S. patents in this
field.During fabric hydroenhancement, water jets entwine surface fibers and yarns and increase
fabric coverage. Some of the major benefits conferred to fabrics from the process are:• improved
strength and abrasion resistance and fraying resistance;• improved fabric coverage, and a softer
hand and enhancement of under-constructed fabrics;• reduction of fabric tension, which provides a
flatter fabric for easier cutting;• a cleaner fabric, particularly in cotton or cotton blends; and•
a mercerized effect on cotton.Hydroenhancement of Glass Fiber FabricsIn the high-pressure laminate
and printed-circuit industry, glass fiber fabrics are used to meet critical electrical,
temperature, corrosion resistance and dimensional stability requirements. Hydroenhanced fabrics are
suitable for this application. The Fleissner AquaTex system is being used successfully by a major
supplier of glass fabric for circuit boards, resulting in its customers delivering higher quality
circuit boards.HydroENHANCER® SystemU.S.-based Textile Enhancements International (TEI) Inc.
provides the HydroENHANCER™ system, developed in cooperation with Finlandbased Valmet Inc. (now
Metso Corp.) and U.S.-based Zimmer Machinery Corp. TEI also has developed a number of proprietary
fabric constructions designed specifically for hydroenhancement.
TEI’s HydroENHANCER™ intertwines outer fibers within and between yarns of cloths.The
technology of the HydroENHANCER system consists of subjecting cloths containing spun yarns to
minute but very high-velocity jets of water to bloom the fabric and then intertwine (Hydro Stitch™)
the outerfibers within and between yarns. The system developed by Valmet uses a batch process with
a multiple reciprocating device. The device is somewhat similar in appearance to a dye jig.The
technique and apparatus provide reciprocating enhancement through a pair of reversible,
tension-controlled, driven fabric spools with the enhancement process placed between them. The
choice of which two of the three manifolds are programmed to be active on a pass determines which
side or sides are enhanced. The fabric finish can be modified by using a recipe to set the number
of passes and the number and sequence of jet manifolds that are activated on each pass with one
loading of the machine.
Summer 2004