Introduction
Three overlapping conferences and an exhibition meant that
only a selection of the available presentations could be covered. Themes included Natural Fibres and
Sustainable Materials, Filtration Opportunities for Nonwovens, Nonwoven
Technology Update, Medical and Biotechnology and Technical Textiles
R&D. The exhibition was small
compared with the Frankfurt version and contained little of interest for
disposable hygiene products.
Keynote: Textile
Trade Trends and Technical Textiles
Kim Glas,
Deputy Assistant Secretary of Commerce for Textiles and Apparel, USDOC,
Washington, D.C., USA and an Obama appointee, listed the top 5 sources of US textiles
and apparel in 2009 as China ($32bn) Vietnam ($5.3bn) India ($4.6bn), Mexico
($4.1bn) and Indonesia ($4bn). Total
imports amounted to $81bn while total exports were only $13.6bn, mainly to
Canada ($3.5bn) and Mexico ($3.2bn). Free
Trade Agreements were the key to reducing this textile trade-gap: 17 of were
already in place and a further 3 were pending, but none so far were with any of
the top 10 countries supplying the USA.
The Trans-Pacific Partnership FT Agreement was facilitating exports to
the Pacific Rim which now accounts for 40% of global trade, and the first round
of talks involving the USA were held in March this year in Australia. The USA,
Australia, Peru and Vietnam will be added to the original members, Brunei,
Chile, Singapore and New Zealand shortly.
In total the Free Trade Agreement countries take 70% of US textile exports
but together they only account for 9% of global GDP.
Support for the textile industry included the
requirement that the Department of Homeland Security bought...
certain clothing
and textiles related to national security from domestic producers. Congress had also granted funds amounting to
$8.3 million to the National Textile Center, the Textile/Clothing Technology
Corp and Philadelphia University.
Furthermore the Department of Commerce’s Sustainable Manufacturing
Initiative would help the textile industry to “go green”.
Technical
Textiles Overview
Michael
Jänecke, Director Techtextil, Messe Frankfurt GmbH, Frankfurt, Germany observed that TT’s have
withstood the recession better than apparel, and in the US and Europe have
avoided the market share losses to Asian producers experienced by apparel. However Asia and Eastern Europe are now
increasingly focussing on TTs with South Korea and China supporting new
investments in this segment.
Considering textiles by country since 2008:
·
French TTs lost 15% of turnover c.f.
35% losses in basic textiles, but some TT specials grew 60%.
·
Italian textiles lost 20-50% of turnover,
5000 jobs and 3000 small companies.
Cheapest mass-market textiles
performed best. Auto, Building and Sport
textiles were now recovering.
·
In Germany, TTs account for 50% of
total textiles and excluding Auto, suffered only a slight decline. The governments economic stimulus is now
increasing demand, especially in construction and geotextiles. For textiles as a whole zero growth is
expected in the near future.
·
Turkish textiles declined to 2004 levels in
the first half of 2009 forcing industry restructuring. There were 30,000 companies with less than 10
empoyees, 150 of these making TTs with a value of $1.5bn, exporting $0.9bn to
the EU, Russia and the USA.
·
Indian textiles employ 85 million people and
account for 4% of GDP (14% of exports).
Growth slowed but there was no recession. Government is encouraging demand growth with
improved infrastructure projects, new medical facilities and automotive
industry growth. They intend to adhere
to “global standards of eco-friendliness.”
·
Russian textile imports have grown by
2% through the recession and the total textile market is now expected to grow
at 30-40% pa with 90% of this being TTs.
Currently 70% of TTs are imported with local producers failing to meet
the demand. Modernisation of textile production is expected to require €3.3bn.
·
Canada has over 400 textile makers employing over
40,000 and producing $6bn worth of goods, about half of which is exported, 82%
being to the USA.
·
South Korea, now the 6th
largest supplier of textiles and clothing is focussing on high value TT’s and
their convergence with IT, biotechnology and nanotechnology. They have secure core technology in auto,
aerospace, construction and medical fabrics.
Government is supporting production of composite fibres, nanotextiles
and aramids for use in semiconductors, batteries and precision filters.
·
Taiwan is experiencing a prolonged
recession in textiles and fibres and is planning reorientation away from mass
production towards high value medical, energy storage and ecological
textiles. TT’s will grow from 10% of
textiles in 2002 to 33% in 2015.
·
China’s economic growth declined to
6.1% for the first quarter of 2009 before returning to the official “feel good”
level of 7.9% in the second quarter.
Over the same period exports of textiles fell by 11% and many producers
are now focussing on domestic demand, where demand for TTs is “tremendous”,
increasing by 11.4% in 2008. Masks,
protective clothing, hygienic and medical products were in high demand.
U.S. Manufacturing
Update: Implications for Technical Textiles
Tom Murphy,
Executive Vice President, RSM McGladrey, Inc., Minneapolis, MN, USA
Said the US Manufacturing Sector has seen
significant challenges over the last two years.
Production levels declined by over twenty percent
and capacity utilization fell to the seventy
percent range. Yet, contrary to public opinion, and
manufacturing’s loss of over 2.1 million jobs since the recession started
in December of 2007, the US manufacturing sector is still the largest in the
world:
·
Productivity has doubled since 1987
·
The US attracts most inward investment (China second and UK third)
·
The US was the third largest exporter after the EU and China, and 57%
of exports were from manufacturing.
·
The US is still the world leader in innovation (patenting evidence)
·
The trade deficit is mainly due to trade with China and Japan: NAFTA
trade was in surplus in 2009 if energy is excluded.
·
The US is falling behind in infrastructure. China committed twice as
much of its stimulus pack to infrastructure as the US (US= $300bn on infrastructure)
·
84% of US energy comes from fossil sources and this must be
replaced.
·
2007 levels of output won’t be reached again until 2012, and no more
than 50% of the jobs lost will be recovered.
What
are the implications for the technical textile industry?
·
Consolidation will be critical for survival to offset the foreign
competition through product differentiation, expanded offerings, increased
market share, the ability to enter international markets and being able to
supplement forward integration.
·
Partnering in both directions in the supply chain with suppliers and
customers will be necessary to squeeze out more efficiency.
·
More TT manufacturers will follow the apparel companies abroad.
·
The demand for polyester is expanding into stretch, microfibers,
recycled, antimicrobial and nonwovens.
·
New fiber development, military fabrics, global expansion and medical
textiles will provide new opportunities for the US.
US
Textiles Outlook and the Importance of Technical Textiles
David
Trumbull, NTA Vice President of International Trade, National Textile
Association, Boston, MA, USA noted that there were signs of recovery
in the textile sector, with March 2010 statistics showing job losses in
textiles levelling off at 400,000.
Finance was still a big issue and the NTA has been working with
government to expand the availability of loan guarantee programs. Despite the title, data specific to TTs was
non-existent, largely because there was no trade association covering this
market. The only TT’s the NTA dealt with
were nonwovens and flock.
The REAL State of the Industry
William C. Smith, Techtextil North
America Symposium Director, Principal, Industrial Textile Associates, Greer,
SC, USA estimated that 25% of all US fibre consumption
went into TTs, a market worth $31 billion in sales. Globally TTs were worth $121bn and had been
growing at an average 3.8% pa until the recession when a 5.5% decline occurred
despite a 25% increase in military textile production.
·
Automotive
fabrics, the largest US TT sector declined by 300 million square yards as car
production fell to 10 million from 16 million. The average car requires 21 kgs
of TTs. China now makes more cars than
the USA. 2010 should see a US recovery
to about 12 million cars, but it will be 2013 before the 16 million mark is
reached again and this assumes that ageing baby-boomers will not make do with
one car, and a smaller one at that.
·
Geotextiles,
flat in 2009 were expected to grow by 5% this year.
·
Outdoor
textiles (awnings, marine etc) declined by 18% in 2009 – flat this year.
Technology
Transfer at the National Textile Center
Dr.
Martin Jacobs, Executive Director, National Textile Center, Spring House, PA,
USA described the National Textile Center as a Federally-funded 8
university consortium supporting the US textile industry through basic research
and technology transfer aimed at improving the global competitiveness of US
textiles. It also trains graduates and
provides the industry with 90% of its needs – 2000 graduates to date, 6 of whom
provided the following short talks.
Molecularly Imprinted Fibers with Recognition Capability
Bogdan Zdyrko, Ph.D., Research Assistant Professor,
Clemson University, Clemson, SC, USA is trying to prepare
artificial antibodies by grafting. Here
an alginate fibre is coated with an epoxy surface such as PGMA (poly
glycidalmethylacrylate) which has the right functional groups to bind to an
antigen. An antigen (e.g. fibrinogen) is
then attached to this surface and surrounded by PEG polymer chains which
encapsulate the antigen molecules and “mould” to their shape. The antigen is dissolved using protease
leaving the empty moulds which are then able to selectively absorb more
fibrinogen. That’s the idea: checking how
well it works remains to be done.
Cellulose/Soy Protein Based "Green" Composites
Dr. Anil Netravali, Cornell University, Ithaca, NY,
USA is trying to make biodegradable composites from sugar cane waste and soy
protein. The bagasse is dissolved in
phosphoric acid to make liquid crystal cellulose fibres (Enka’s old Bocel
Process). These are fibrillated and
embedded in a soy protein matrix to give composites to compare with Kevlar
embedded in the same soy protein. The
cellulosic composite tensile strengths are about 60% of the aramid composite
but the extensions are 3 times greater.
Dr Netravali is also trying bacterial cellulose as a reinforcement for
soy protein. Applications in ballistics
are envisaged.
Engineered Reinforced Structures from Short Fibers
Yong K. Kim, Ph.D., Chancellor Professor,
University of Massachusetts, Dartmouth, MA, USA is air-laying
short cut fibres through two rectangular boxes arranged in line, one containing
electrodes which orient the fibres in the machine direction and the other containing
electrodes which orient the fibre in the cross direction. Field strengths of 20-40kV/m work well with
fibres of 10-25mm length. Nylon and
Polyester fibres appear to work well to give a unique cross-laid structure with
fibre layers preferentially arranged at right angles.
Electrospun Composite Nanofibers for Lithium-Ion Batteries
Xiangwu Zhang, Ph.D., Assistant Professor, North
Carolina State University, Raleigh, NC, USA made LiFePO4/C composite nanofibers using a
combination of electrospinning and sol-gel techniques. Polyvinyl alcohol
(PVA) was used as polymeric matrix of the LiFePO4/C composite
system, and was converted to carbon in a calcination/carbonization step to
improve the conductivity. These were intended for the cathode of the
battery. The anode was made by electrospinning silicon nanoparticles in
PVA and then carbonising to get a silica/carbon composite. Batteries with these electrodes should
exhibit higher power densities, longer life and a wider operating temperature
range.
Challenges in Advanced Nanofiber Wound Dressings
Marian G. McCord, Ph.D., Associate Professor, Textile Engineering,
Biomedical Engineering, North Carolina State University, Raleigh, NC, USA observed
that modern high performance wound dressings using hydrocolloids, gels, gel
fibres etc tend to be costly so she is exploring coating conventional cotton
dressings with nanofibres. While this is possible using
electrospinning, the nanofibres adhere badly, and are not very durable. So she has tried using APPT (Atmospheric
pressure plasma treatment) on both the substrate and the nanoweb to improve
bonding. In fact the APPT and
electrospinning have been carried out on the same roller. Peel tests and Gelboflex durability testing
proved the benefits of using APPT.
Logistics of Closed Loop Textile Recycling
Jeffrey A. Joines, Ph.D., Assistant Professor,
North Carolina State University, Raleigh, NC, USA has modelled
carpet recycling to nylon polymer within the Carpets of America Recycling
scheme logistical framework. He concluded
that unless virgin nylon polymer prices increased substantially, any such
scheme would be uneconomic. He is now
studying polyester and mattress recycling.
The
Affects Of Increased Surface Area Media On Air Filter Performance
Dave
Healey, Director, Synthetic Technology, Hollingsworth & Vose Company, East
Walpole, MA, USA reviewed the problems of improving the performance
of HVAC bag filters which generally have to fit in 24” square ducts. Adding more pockets, lengthening the pockets
and tapering the pockets have diminishing returns: the extra surface area
failing to yield the expected reduced pressure drop because the pockets
interfere with their neighbours and the duct walls. Electretting the fabrics helps, but EU
regulations now mandate discharging the filters with IPA before testing, and in
Sweden, continuous testing over 6 months is required for filters carrying an
electric charge. Moving to finer fibres
with meltblowing or electrospinning improves the mechanical efficiency of the
filters but gives face-loading problems and shorter filter lives. H&V have therefore developed meltblown
with a wavy surface - “Nanowave” – which increases surface area and mechanical
efficiency without face loading, and increases the dust-holding capacity by 2-3
times. The benefits can be translated
into reduced pressure drop and hence energy savings. In a 6 month comparison with a similarly
rated electretted filter, the Nanowave showed constant filtration efficiency
around 40% compared with a 60% efficiency for the new electrets which declined
to 20% by the end of their life.
Super High
Surface Area Fibers
Carol
Clemens, President, Allasso Industries Inc., Raleigh, NC, USA has used
sheath-core bicomponent fibre technology to make multilimbed fibres with very
high surface areas. Sections shown had
32 lobes where the earlier 4DG fibres had 6 lobes obtained from shaped
spinneret holes. The 32 lobe shape is
the core of the fibre, the skin being sacrificial and dissolved the fibres have
been processed into fabric.
This configuration gives:
·
High absorbency and wicking characteristics
·
Deep channel filtering effective for bacteria
·
Exceptionally high surface area that can be
functionalised for biomedical applications
·
A 20 micron diameter winged fibre gives the same
surface area as a 0.3 micron meltblown.
·
The large fibres resist compression (unlike
meltblown of similar surface area) and the channels can take dust particles
without affecting the pressure drop.
Actually the winged fibre is oval with
an aspect ratio of 0.54 (width 17 microns, thickness 9 microns). It is available as PET, PP, PBT, PA, and PLA
and can be produced as spunbond, staple or short-cut. Applications envisaged include air and water
filtration, biomedical filters and adsorbers, battery separators, artificial
leather, wipes and absorbents.
Breathable
Composite Nonwovens
Mike
Budai, Coating and Laminating Manager, Dynatec, Inc., Hendersonville, TN,
USA explained how their hot-melt
laydown equipment could do everything from lay uniform 100gsm webs 16ft wide to
coating a single elastomeric yarn on a diaper production line. Fibre deposition could be random or in
controlled waves, and if exceptional web weight uniformity was needed, melt
flow could be provided by using a metering pump for every nozzle. The adhesives could also be applied in
horizontal or vertical stripes of varying width or in box shapes or just on the
edges of a nonwoven or film. Laminates
could therefore be made with various levels of porosity, and the hot melt could
also fix powders such as superabsorbent, active carbon powder, silica gel or
calcium carbonate between the layers.
Durable
Elastomeric Microfiber Nonwovens
Nagendra
Anantharamaiah, The Nonwovens Institute, North Carolina State
University, Raleigh, NC, USA is developing nonwovens for performance
apparel and observes that the hydroentangled spunlaid microfiber nonwovens made
from segment-pie bicomponent fibres suffer from the “Velcro Effect” where the microfibers
snag on rough skin to spoil the tactile property of a very smooth surface. Furthermore they tend to be hard to dye and
show poor pilling and abrasion properties.
Fibrillating Islands in a Sea fibres
which have a polyethylene sea which fractures to liberate the nylon core fibres
during hydroentanglement looked interesting because the fibrils from the sea
enhanced the bonding and gave better cover and strength. However these fibres need very high pressure
water jets and give suede-like fabrics – which was felt to be a disadvantage
for performance apparel.
Tipped trilobal bicomponents fracture
with ease and if made with 75% nylon tip and 25% polyethylene core yield four
fibres of equal denier and a tendency to crimp on hydroentanglement. The resulting fabrics were easily stabilised
by thermal bonding, soft and durable and free of the Velcro effect.
Further extensions to tricomponency
become possible if the core of the trilobal is hollow or has another core
polymer within. The elastomers of the title were mentioned but briefly: if used as cores, the fibres were hard to
spin.
Aerosol
Filtration with Electrospun Nylon-6 Nanofiber Webs
Bong-Yeol
Yeom, The Nonwovens Institute, North Carolina State University, Raleigh, NC,
USA has made nanofibre webs by electrospinning 12% nylon 6 dissolved
in 3 parts of formic acid mixed with 7 parts of acetic acid. Up to 5% of boehmite nanoparticles (7nm
average diameter) were added to the solution and electospinning used the
Elmarco system to coat a 20gsm PP meltblown nonwoven. Fibre diameters were pretty consistent
averaging around 80nm regardless of the boehmite concentration.
Filtration performance was assessed by
dioctyl phthalate penetration as-spun, after discharging and after
electretting. The effects of charge
dominated the results. The boehmite
nanoparticles did slightly improve the aerosol filtration performance, but this
appeared due to the higher electrostatic charge held by the fibres containing
it.
Carded
Nonwoven Web Weight Levelling
Everette
Scarboro, Jr. Regional Sales Director – North America, Oerlikon Textiles, Charlotte, NC,
USA showed how crosslapped web weight varies considerably from side to center
to side. Crosslappers have been modified to minimize this “smile” effect but it
was not until additional sophisticated controls were
employed that true leveling was accomplished.
For needlepunch nonwovens, the tensions
created by needles stopping web motion with every punch add to the problem and
elliptical needling (where the needles move with the web) provides a solution
albeit at high expense. Profi-line CV1
from Dilo, and ProDyn from NSC provide
further solutions by varying the card web basis weight periodically so that
after cross-laying a “frown” profile enters the needleloom to allow a level
final product.
Oerlikon’s WebMax solution can be
retrofitted to existing lines. It goes “in
the crosslapper or between the card and the crosslapper” to contol card web basis weight to achieve the
same effect at lower cost, probably by web-drafting, although Mr Scarboro was
deliberately vague about mechanisms.
Because most needlepunched nonwoven buyers specify a minimum thickness,
reducing thickness variability allows the basis weight to be reduced and the
material savings from WebMax give
payback in less than a year.
Machinery
and Methods in the “Nanofiber” Meltblown Process
Timothy
Robson, Business Development Manager, Hills, Inc., W. Melbourne, FL, USA described a new
method of making meltblowing dies by photochemical etching semi-circular
channels on the insides of the die tip plates so that when conjoined they form
capilliaries. These capilliaries can
have diameters of <.1mm and L/D’s of >100:1 where traditional drilled
holes are limited to ~0.2mm in diameter and ~10:1 L/D. High L/D capilliaries allow running at the
low throughputs required for nanofibre production while maintaining the high
die-tip pressures needed for good polymer distribution, and hence good web and
filament diameter uniformity.
Furthermore the etching process allows higher hole densities and so
greatly improves throughput of ultra-fine fibres. Because the new dies can withstand higher
pressures, polymers such as PA and PBT can now be processed into nanofibres.
One filtration example was given. Here a 2 gsm nano PP Meltblown on a 17 gsm
PP spunbond gave almost the same filtration efficiency as a commercial HEPA
filter (30 gsm standard PP Meltblown on a 70 gsm PP Spunbond) but with half the
pressure drop.
Ultrasonic
Processing of Nonwovens
Bill Lynch, Key
Account Manager, Hermann Ultrasonics, Bartlett, IL, USA provided the
traditional paper on sonic bonding noting that it is a reliable and efficient bonding process which meets sustainability
targets by eliminating the need for adhesive materials and high thermal heat
bonding processes. Ultrasonic processing
is still used for bonding and laminating multi layers of nonwoven materials and
films improving the strength, performance, appearance and feel of the lamination.
Other uses include embossing, perforation, slitting, cutting and splicing for Hygiene, Medical, Filtration, Wipes,
Construction, Automotive and Home markets.
More interesting was a brief mention of the Ultraspin rotary sonotrode
systems that help feed thicker or fluffier type materials at high speed, and a
question regarding the glue-free diaper target which indicated that Hermann is
working on laminating 12-13gsm PP backsheets to PE film, and this is proving
tricky. Bico PP/PE spunbond could
however be laminated to PE film without difficulty.
Needlepunch:
Competition for spunlacing?
Terry
Purdy, Sales Manager, Dilo, Inc., Charlotte, NC, USA also provided a
traditional paper - on needlepunching. Among
descriptions of the multitude of combinations of machinery needed to make all
types of nonwovens, with or without needling, one slide covered a new
concept: Hyperlacing. This looked like an artificial leather
production line but here the 8 needlooms were set up to produce nonwovens in
the 30-60 gsm range for wiping applications.
Needles with a single barb intended to carry a single fibre through the
web were used, and the line was said to be capable of running at 100m/min. Symbols on the diagram suggested the first
loom was downstroke, the second upstroke and the remaining 6 were needling from
both sides with elliptical board motion.
Data on capital cost and nonwoven properties compared with
hydroentanglement systems was not forthcoming.
Inorganic
Fillers In Fibers For Nonwovens
Larry
McAmish, Technical Services Manager, IMERYS Performance Minerals, Marietta,
GA, USA presented the results of trials conducted at
several universities. In all cases the spunbonds maintained most of
their physical properties up to 20% calcium carbonate in the fibre, but
the tenacity dropped by 50% at 50% loading. With spunlaced staple fibres,
nonwoven strengths were increased by the calcium carbonate loading presumably
due to surface friction increases. There
were also some novel effects associated with suspending high density,
inorganic particles within a lower density polyolefin matrix such as the
improved stability of an electrostatic charge on this composite material
due to triboelectric effects. In staple fiber applications, there were
additional benefits of improved web formation both in carding and
spunlacing. There were also some aesthetic benefits, and sustainability advantages
resulting from the considerably lower carbon footprint of the mineral
phase.
Medical
Textiles – Where are We Heading Now?
Deborah
K. Lickfield, Ph.D., President, Lickfield Consulting, LLC, Easley, SC,
USA provided assorted data on the market:
·
World speciality textiles market had increased from
21 million tonnes worth $115bn in 2007 to 22 million tonnes worth $120bn in
2009
·
The Medical subsegment was worth $8bn in 2007.
·
In 2008, USA, EU and Japan the leading medical
market segments by revenue were Wound care (32%), Incontinence care (19%),
Patient Care linens (17%), Drapes (15%), Gowns (7%), Masks (5%) and Sterile
Wrap (5%)
·
K-C, J&J, SCA, Molnlycke, Cardinal and P&G
were listed as the main global competitors in primary medical textiles –
P&G for Incontinence product and wipes.
Almost any new polymer and fibre
technology would attract interest from medical product developers. There is huge interest in cross-sectional
shapes and anything else which gives high surface area, or incorporates active
ingredients or novel surface treatment.
Advanced wound care is particularly
active. Globally $5.6bn was spent on
chronic wounds in 2007, and there are over 4 million in the US where a care of
a single chronic wound can cost up to $80,000.
Current products include:
·
Moist products:
Alginate, films, foams and hydrocolloids
·
Active products:
the above with haemostats or components to accelerate healing or
antimicrobials such as silver.
·
Quikclot® - gauze with an aluminosilicate
nanoparticle haemostat.
·
Gauze with negatively charged phosphoric acid to
extract proteases from healing wounds.
·
Coolmax® FreshFX medical hosiery with silver ions.
·
Celliant® fabrics from fibres containing
ingredients to oxygenate the skin and increase blood circulation.
Use of
Copper Oxide in Medical Devices
Gadi Borkow,
Ph.D., Chief Medical Scientist, Cupron Inc., Gibton, Israel described how copper oxide is spun into fibers
endowing them, and fabrics made from them, with potent broad-spectrum
anti-bacterial, anti-viral, anti-fungal and anti-mite properties. The risk of any adverse reactions to dermal
exposure to copper is known to be extremely low, and now animal studies have
shown the fabrics to be free of irritation or allergenicity issues. The EPA has approved the use of copper
(metal) as an antimicrobial worksurface.
Applications under development include:
·
Athletes foot prevention socks
·
Diabetic ulcer healing socks
·
Bed linen to reduce MRSA contamination in
hospitals.
·
Anti dust-mite bed linen (Now approved by the EPA)
·
Anti-viral face masks
·
Anti-viral filters to remove HIV from breast milk
(with funding from the Bill Gates Foundation)
·
Tissue regeneration dressings: (Copper works through angiogenesis whereas
silver is inactive)
·
Wrinkle-reducing pillowcases (make skin look
younger).
Low Cost
Conductive Nonwovens
Davis Khan, Research Scientist, Kimberly-Clark,
Dallas, TX, USA explained
that he was at TechTextil because K-C had developed a great new raw material for
applications outside K-C’s usual domain and was therefore available to licence. Why had they developed it? Because there was a need for low cost
conductors in consumer products and they had 135 years of experience in
papermaking. The new material in
question was not a nonwoven but a conductive paper made from 10%-30% 3mm carbon fibres and 90% pulp along with
wet-strength enhancers and colorants as necessary. This could be used as-is, or hydroentangled
into other nonwovens, or fed into air-laying Co-Form style. At 40 gsm with 10% carbon it would cost
~$0.37/m2 and at 75 gsm with 25% carbon fibre it would cost $0.97/ m2. The resistance can be tailored, and the
positioning of the paper in a product can be arranged to give targeted,
effective heating at low cost. For
instance a paper with 30% carbon fibre carrying a 130mA current from a 7.5v
power supply would heat at 840W/m2.
In addition to
semi-disposable heating pads giving a 97oF surface for 8 hours from
a 3v Li-ion battery, the paper could provide 115oF to release scent
from gels, liquids or waxes, and allow “easier cleaning of grease and oil” when
used in a mop-head. It could also be
used as radiating elements in RFID tags or smart textiles.
Ultrasonic bonding
and laminating has been shown to shatter the carbon fibres and break the
conductivity of the cellulose paper. With the right pattern roll, ultrasonics
can create circuit patterns. This technique has been used to make simple
membrane switches and a disposable keypad.
Calvin Woodings
27/5/2010
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