Nonwovens Technology Conference Mainz : April 24-26th 2001

Despite being scheduled simultaneously with the Tech-Textil 2001 Exhibition and Conference in neighbouring Frankfurt, this Marketing Technology Services meeting attracted 140 international delegates. As in past meetings in this series, strategy and air-lay technology themes predominated, but papers from both Perfojet and Fleissner heralded some new thinking in hydroentanglement bonding.

Key Points

Main Spa ( Italy) is starting a new flexible air-lay line and is prepared to run trials with lyocell.

Rieter-Perfojet has installed the first HE bonding head on a spunlaid line, apparently to entangle pulp into the spunbond for wiping applications.

Fleissner is oscillating the last HE nozzle to make fabrics free of jet lines.

Both HE machine makers are focussing on efficiency and economy rather than the extremes of pressure and width.

A pulp-free diaper made from 2-layers of film with SAP in channels, said to be able to deal equally well with thin and thick fluids is to be commercialised.

Superabsorbent-containing soaker pads for meat & fish retail packs can be air-laid and converted on panty liner machines.

An 11gsm spunbond coverstock can be made with the same strength and porosity as a 15 gsm product if 350 MFR resin is converted at high spinning speed.

Eastman’s EASTAR BIO® biodegradable co-polyester has been melt blown and spunlaid successfully.

130,000 tonnes of pre-formed core is used in fem-hy and inco products. The first diaper to use the core is now on the market.

Data from K-C’s Kellenberger patent on AUL/Overnight leakage has been found wanting in an analysis by MTS.

Air-Laid in Meal Service

Johanna Svanberg of Duni AB said Duni has focussed on the meal service market since 1972 guided by a mission “to enhance any eating and drinking occasion”. Having introduced the first coloured napkin in 1954 they now produce a wide range of disposable table-wear including paper cups. Linen-like latex-bonded air-laid napery, often brightly coloured and printed is perhaps the best-known Duni product. The market, and hence their product development, is heavily influenced by clothing and interior design fashion, products changing twice a year to reflect trends in summer and winter season colours, textures and prints. Last year, Asian character prints were “in”, next summer the themes will be “Mirage, Innocence, Frivolity and Sensation”. Technically speaking:• Duni has a new air-lay forming head (Danweb) to complement the M&J systems they've used for years.
• Most of their printing was flexographic.
• They've developed biodegradable bonding systems, but there's no demand for them as yet. She commented that there were however spin-off benefits, but could not say more. (maybe easier waste recovery)
• Cost reduction was as important as staying in fashion. The key was to make no waste – because bonded airlaid could not be re-fed – and to reduce energy use.
• They used LPG for drying, but now the prices of this fuel were increasing so dryer exhaust heat recovery would be their next major project.
• Environmental concerns surrounding disposables had to be addressed: their echo-profiling (sic) showed that air-laid table-wear was no different to laundered cotton for total environmental impact.
• The European Community's Integrated Product Policy (Feb 2001) would stimulate a) a consumer demand for “green” products, b) a business leadership to develop green products and c) a price incentive to switch to green products.

Why did European-style tablewear not do well in the USA ? Ms Svanberg thought it should be a big opportunity, but felt Duni still had to find the right distribution channels.

Fibervisions Bico Fibres

Allan Rasmussen of ES Fibervisions took us once more through the ES family of thermal bonding fibres now on offer. Along the way, the following points appeared more interesting than most:
• A new polymer additive that is now used in the whole range of products has solved their problems with fibre yellowing on storage.
• Their capacities for bico fibre are 12,000 tpy in Athens Georgia , 15,000 tpy in Varde Denmark , 10,000 tpy in China , and Chisso has 45,000 tpy in Japan of which 10,000 are available for export.
• The AL Adhesion C product which bonds well to cellulose and cuts dust levels in airlaying uses a hydrophilic additive grafted into the skin polymer.
• Their low-melt (95 o C) fibre gives very soft nonwovens with poor recovery from compression, but it can be used as a laminating layer or even a coverstock.
• While they offer up to 20mm for air-lay, 6mm is the longest fibre used commercially.
• The 17 segment splittable PP/PE bico (Chisso EDC) does not split in the air-layer.

Honeycomb structures

Ronald Smorada of Versacore (in another run through his IDEA 2001 slides & video) explained that his 3-D nonwovens process was a new application of the technology previously used to make paper, aluminium and Nomex honeycombs. Using nonwovens intermediate in properties between these low and high technology extremes could create new markets. He described the opportunity as a market development exercise in transportation, furniture, civil engineering and filtration sectors. If the machine worked at its optimum settings with 100mm wide, 100gsm tapes it would produce 0.5MMlbs, or 20,000 m 3 product per year. On-line slitting had been developed to allow the 100mm tapes to yield several layers of thinner honeycombs. Details of how the product would be packed for shipping were not provided, but with nonwovens, slabs of the honeycomb could be flattened and re-expanded at the destination. In response to questions, cost could be estimated by assuming 65% of the final cost would be the cost of 100gsm 100mm tapes. This worked out to $20-$85/m 3 , compared with $3000/m 3 for Nomex honeycomb. The process could be made to work on non-thermoplastics using adhesives, but this is regarded by Versacore as an unattractive niche market.

An Alternative Air-laid Strategy

Domenico Milesi of MAIN Spa estimated total air laid capacity to be ~350,000 tonnes currently and growing sufficiently fast to justify his investment in the technology. His strategy had been to:
• Get some money
• Decide what sort of factory to spend it on
• Build the factory
• During the 16-month construction process, work out where he was going to sell the product.
• Hire staff, especially an excellent R&D team to develop new products.

The key to succeeding with this delightfully quick and dirty approach was in his view to move into a fast growing market where the future was unpredictable (so why waste time trying), and to spend a little more on the kit so that the plant was versatile enough to be able to produce a wide range of products. His 10,000 tpy Dan-Web line had four forming heads followed by foam application of latex from both sides. Each head could take 2 different man-made fibres and 2 different pulps, and he could add SAP between heads 2&3 and/or 3&4. 576 different combinations of raw materials are theoretically possible. Having completed construction last June, he was now developing products to customers specifications and had already identified a newish sector suited to the output: soft-fruit packaging. In Italy alone, the potential here, at 20-25,000 tonnes/year was more than enough to take his entire output. From his base at the instep of Italy , he saw the possibility to ship into France , Greece and Turkey as well. Asked about air-laid diaper cores, he thought their production was very close now.

A new HE Strategy - Part 1

Klaus Völker of Rieter-Perfojet described the strategy changes since the Rieter takeover. “Jetlace 2000” had been a rather short-sighted designation for a process developed at the end of the 1990's so they were renaming it “Jetlace 3000”. The name change also heralded a new direction which would value efficiency and economy over ever-wider ever-higher-pressure systems. Higher water pressure hit investment and energy costs, both doubling for every 100 bar increase in pressure (above 100bar). At 100 bar there were ways to use water more efficiently, e.g. perforated flat-screens rather than woven wire belts to support the web. With these screens, there was a trade off between bounce-back and flooding, but tests had shown that only 8% open area gave sufficient drainage and much enhanced fabric strength. Fluid dynamics studies had allowed changes in the design of the injector strips and water distribution channels to allow products previously requiring 300bar water to be made with only 180 bar. In addition to these efficiency changes, the cost of an HE bonding zone was now 30-40% lower than 10 years ago. Other points of interest:
• Fabric strength was unaffected by line speed up to 100 m/min, but above that pressure increases were needed to maintain a given strength level.
• The highest commercial line speed was currently 230m/min (4meters wide with a 17,000 tpy output).
• The Airlace system was illustrated with an HE zone either side of the M&J air-layer, but it was also possible to sandwich the pulp between two card webs. In this case wet-waste levels were horrendous (10 tonnes/day had to be dealt with).
• Pre-entangling the card web before laying the pulp allowed the pulp to bond better in the second HE zone because it washed into the corrugated surface (jet lines).
• They sold their first HE head for use on spun-laid last year, mentioning a spun-laid/airlay pulp/HE system for wipes.
• Smaller holes give more efficient entanglement – now using less than 100 micron.
• Cavitation problems were significant above 300 bar, but manifold design had helped.
• Demineralised water was more aggressive than ordinary! (Jet strip life reduced by faster erosion)
• All finish was removed from fibres by HE so PP emerged hydrophobic. Defoamers had to be added to neutralise the finish in the water system.
• Jet strip cleaning frequency had improved from once/shift to once/week with the new filter systems.

Fibre-Free diapers?

Harry Boich (Consultant ex Corovin) has developed, patented and obtained finance to commercialise a “body hygiene liquid management system”. He argues that fibres are poor transporters of liquid because of the difficulty in getting the capillarity effects right. He goes on to say that absorbtion and transport, both needed in a diaper cannot be achieved with a fibre structure, and that fibrous cores and topsheets cannot be made to deal equally well with thin and thick fluids. His patented solution is to use films with tapered channels to conduct fluid away from the crotch area and into foam/SAP reservoirs in the waistband area. From the unhelpful slides it appeared that alternate channels contained SAP, the empty channels being designed to maximise capilliarity. It was not clear how his claim that the product would work equally well with thin and thick fluids could be justified. Lab test data is said to be excellent, but consumer testing has not yet been carried out.

Market Update

Johns Starr reviewed industry competitiveness in the light of increasing raw materials prices and new capacity coming on stream.
• He saw brief overcapacity in spun-melt nonwovens for hygiene, with new lines full and older lines underutilised.
• Global demand would reach about 1.1million tonnes in 2005, and some older lines would have to close if they could not move higher value products. (Retrofitting of microdenier/bico capability?)
• Apart from some overcapacity in Miratec at PGI, he saw spun-lace in balance with demand reaching 250,000 tonnes by 2003. (he uses best estimates of the most likely output of the lines to get the capacity figure, ignoring the manufacturers nameplate capacity.)
• Full-cost of all-staple European spun-laced from the most efficient lines would be around DM8/kg, raw materials accounting for half of this.
• Materials and fixed costs for airlaid core at 500 gsm would about $1/m 2 with 90% of this being materials.
• Full cost of needled polyester would be around $2/m 2 with materials amounting to $1.1/m 2 , but no basis weight was provided.

In response to questions:
• PET spunbond would grow more slowly than PP, but had good prospects in filters, automotive, roofing and construction. (The recent start-up and close down of a new US line was a hiccup).
• Carded/thermal coverstock has about 20-40% of the market and will decline further.
• Carded/latex-bonded ADL was still in use thanks to new investment in high capacity lines.

Nanofibres Update

Michael Wehmann of Nordson Fiber Systems presented selected slides from several earlier presentations on microfibre production.
• JM1 meltblowns had a 1.5 micron mean fibre size: JM2 had a 1.1mmfs with a standard deviation of 0.464
• Finer fibre production needs better quality polymers.
• Moving to 800MFR PP gave a fourfold improvement in productivity when spinning 3 micron fibre.
• Meltblowing splittable fibres and then hydroentangling could make “Nano” fibres them.
• Islands-in-a-sea (900 islands) could be meltblown and split to give fibres in the 100 to 800 nanometer diameter range.
• Electrostatic spinning could give 0.05 micron diameters.
• “Spin coating” appeared to be electrostatically-assisted centrifugal spinning involving a membrane as the spinnerette.
• A second slide with the same “spin coating” title referred to the University of Texas (Dr. Paul) production of carbon nanotubes a few atoms wide as “soot” from vaporising graphite electrodes in a helium atmosphere.
• Dr Ghosh at NCSU has improved filtration by adding 5% of electrospun nano-fibres to meltblown.
• Nordson had co-form experience (they could blow pulp into the melt-blown.
• Die holes were now 0.3 to 0.4 microns for 3-5micron fibres. 0.1mm holes could be made with lasers..

Superabsorbent Soaker Pads

Scott Tomlin of Stockhausen described how superabsorbents could now be used in soaker pads under pre-packaged meat and fish portions. 13.5 billion of these were used annually in the USA , and could use 40,000 tonnes of airlaid nonwoven if each pad contained 1 gm of SAP. 60-70% of the pads were used for red-meat. The US market was thought to be worth from $75MM to $120MM. Compared with the commonly used tissue/film pads, Favor-Pac® SAP/air-laid pulp contained in a sealed perforated film pouch had many advantages:
• Better protection against leaks.
• Better, more hygienic appearance.
• Higher perceived food value.
• Lower repacking costs at the retailer.
• Fluids which could be contaminated with salmonella etc could be immobilised and disposed of more safely.

Compared with a SAP-free control pad, the addition of 0.75g of Favor-Pac® doubled the absorbency and increased the retention of fluid 8-fold. Absorbency under a typical chicken load was increased from 57 to 92 gms and the fluid remaining in the tray when discarded was down from 42 to 7 gms. Safety issues had been dealt with in the USA by getting FDA approval for Favor-Pac® for indirect food contact 2 years ago. In Europe testing at TNO was establishing conformance to the limits for global migration of monomers. Monomer levels would have to be declared, and continuous monitoring of pad production would be needed. Some problems:
• Dosing of 0.75gms of SAP was too variable.
• Getting older, low productivity machines set up to handle SAP was costly.
• Overall cost of the new pads is hard to justify for retailers.
However Mr Tomlin was confident that the problems would be solved, and that the soaker market was similar to the diaper market when diapers used 55gms of pulp.

It would probably be easier to adapt a panty-liner machine to make the new soakers than it was to retro-fit SAP handling to the soaker pad process.

A new HE Strategy - Part 2

Jürgen Heller of Fleissner continued the theme set by Rieter-Perfojet and emphasised the potential economy of HE bonding. He put 1999 actual production at 230,000 tonnes, about twice the level reached in 1995 with growth expected to continue. 60c/lb fibre could be converted into roll goods with a value of $2.7/lb and there was still room for efficiency increases. For disposables, energy costs were only around 1% of the roll goods cost. On the basis of a 3.5m line working at 100m/min for 7200 hours/year to make 60gsm nonwoven, a 1% increase in efficiency would give $600,000 per year more revenue, and in many plants an increase of 10% in efficiency ought to be achievable. Lower pressures, in addition to the direct savings of energy would allow jet strip life to be increased dramatically (“from days at high pressure to months at medium pressure”). Jet cleaning interval could be extended to weekly or even fortnightly by tighter filtration. One innovation appeared: an oscillating last nozzle to kill jet lines. The vibration had to be low amplitude and high frequency to be effective. Illustrations of 3D water-marking effects achieved by using patterned drums were shown. Drying energy? About 1 KwH per kg of water going into the dryer, and for PES they achieved 1 kg water per kg fibre at the dryer inlet. For viscose the figure was 1.3 kgs water/kg fibre. Had they tried denser fluids than water to get more energy transfer? No.

A new Spun-Laid Strategy?

Anders Moller of Ason engineering made a case for spunbond producers to emulate the tissue paper industry rather than the newsprint sector. He thought very big inflexible machines were wrong for a rapidly changing nonwovens industry and thought the way forward involved:
• Smaller machines closer to the markets.
• Machines capable of running any fibre-forming polymer with minimal change-over time.
• Machines capable of making bico fibres with no capacity penalty.
• High spinning speeds to allow a) economic production of sub-denier fibres or b) higher throughput per metre width, and/or c) much stronger filaments.
• Higher hole-density in the jets (productivity/metre)
• Removing the need for SMS by achieving the same average denier in direct high speed spinning of strong continuous filaments.
• Using high MFR polymers, which worked well at speeds above 4500m/min. For instance 700 MFR PP could be spun to 0.2 denier/fil at 6,000 m/min.
• Targeting textile markets (like Freudenberg with Evolon®)

Such processes would allow the basis weight of coverstock to be reduced while maintaining cover and tensile strength. (11 gsm PP made from 350 MFR resin at high speed gives the same hydrostatic head as 15gsm made from 35 MFR.). Trials with Eastar Bio™ copolyester on Ason equipment in the last month have revealed excellent spinnability at speeds above 4500m/min to give 1 dpf fibres and fabrics from 17 to 120 gsm. The 105 o C melting point resin was spun at 205 o C and bonded at 80 o C. There was some evidence that the polymer degrades in sea-water also.

Mr Moller thought electrostatic spinning was many years from commercial reality and would be difficult to operate above a kilo per hour per metre width. His process could make 0.4 denier fibre at 100kg/hr/m/beam.

Inorganic Biocides

Ken Code of Biolargo Technologies Inc., a start-up company about to go public on the NASDAQ exchange, saw the possibility of making air-laid nonwovens the carriers for a powerful disinfectant which would allow “Universal Precautions” to achieve portability in the form of pads and wipers, bandages, disposable clothing, food and hospital service nonwovens and packaging for dangerous liquids. Precisely how this would be done was a little unclear, but the following points were gleaned:
• Iodine would be used at levels below its water solubility limit (337ppm) to provide a cheap but intense kill rate. (log 6 in 5 minutes quoted).
• Copper was involved to give a background (log 3) kill over extended periods to maintain “sterility” after the iodine release.
• These inorganics would be carried in a SAP. (Stockhausen's Favor Pak 100 mentioned as being dosed with 5 to 400 ppm of the active ingredients.)
• Some interference was noted: SAP swelling was reduced by the polyvalent metal ions, and the efficacy of the antimicrobial was reduced by the swelling of the SAP.
• The immediate target market for the airlaid was packaging for the 5 billion Vacuutainer tubes sold by Becton-Dixon to transport samples of body fluids. Here several aspects of “universal precautions”, i.e containment (of spillage), isolation, neutralisation and disposal, were dealt with at the same time as providing a cushion against breakage.

In response to questions Mr Code said that the iodine concentration was too low to cause either the skin irritation or the staining familiar to those who used the early disinfectant. “Copper kills by acid hydrolysis”. The SAP loaded with Cu and I 2 is being converted into airlaid by Concert in Canada . Polycarbonate plastics, like copper, are “natural killers” of bacteria.

Cost effective diapers from pre-formed cores?

Donald Young of Rayonier considered the difficulties of getting a diaper maker to choose pre-formed cores over making his own. Fem-Hy makers and inco-pad makers had made the switch, and the use of airlaid cores were growing nicely in these sectors, but so far only one diaper maker has put a product with a pre-formed core on the market. Fem-Hy and Inco sectors account for about 680,000 tonnes of core materials each, the former using 110,000 tonnes of pre-formed C-fold core, the latter 27,000 tonnes. Diapers, with 2.9 million tonnes of core and “zero” pre-formed are clearly the big target. Cost was the key, and because diaper producers wanted pre-formed core to have the same cost-performance as regular cores, the target price for pre-formed could be calculated as $34.75/thousand diapers. The best achievable with pre-forming was now $39.21/thousand. One solution proposed by Mr Young was to try to persuade diaper makers to look at the total system cost, not just the core costs. If waste, packaging, transport and conversion costs were included, savings in these non-material items allowed pre-formed and conventional diapers to reach the retailers shelves at the same total cost – said to be $55.60/thousand. He saw further benefits arising from the fact that the preformed cores could be made lighter than conventional cores. His air-laid capacity slide gave 348,000 tonnes as the current global figure, with 450,000 tonnes expected by the end of 2002. P&G's air-laid capacity was put at 24,000 tonnes and McAirlaid's nominal 40,000 was actually 20,000 tonnes. Mr Young's paper was not in the proceedings.

Durable biocides

Claudio Darpin of Sanitized AG reviewed the need for antimicrobial additives and the factors to be considered in choosing the right type for a given nonwoven or fibre.
• Natural and cellulosic products were best treated by padding or spraying the organic biocides either directly or in a binder. Wash-fastness for the life of even a durable textile was achievable on these fibres by this method.
• For thermoplastic synthetics several approaches are possible, but the inclusion of the agent in the polymer via a masterbatch worked well in most cases.
• Active organic additives were suitable for the lower melting PP and PE fibres. (E.g. Sanitized® MB P 96-60 at 2.5% in PP)
• Inorganic additives were needed for PES and PA (melting points above 250 o C) and silver based products were favoured. (E.g. Santized® Silver, where the silver was in a white ceramic carrier)

The silver product conferred antimicrobial activity for 7-10 years, and a new material with a 15 year guarantee was now under development. A wash-fastness of 100 cycles using a standard ISO 95 o C wash with bleaching chemicals could be achieved. Mr Darpin agreed that the materials were over-designed for disposables use. The chemistry of the organic Sanitized? It was a heterocyclic substance.

Air-laid Throughput increases

Jim Westphal of Troika Nonwovens (formerly with Merfin and Buckeye) was now representing Dan-Web A/s to give a paper on improving the throughput of air-laying with drum formers. The trials had involved treated and untreated pulps alone and in blend with both 4mm and 6mm bicomponent fibres at 10, 20 and 30%. 100gsm webs were made using 37mm 2 slots in the forming drums with 100% and 125% forming air velocities.
• The treated pulps gave substantially higher throughput than untreated, in some cases nearly doubling the capacity of the former.
• Increasing air velocity by 25% gave a small (8%-10% i.e. uneconomic) improvement in capacity.
• Adding 4mm fibres to treated pulps did not affect the throughput, but 6mm fibres reduced the capacity; 1.7 dtex having a greater effect than 3 dtex. The losses ranged from 6 - 24% for a 10% blend to 39-46% for a 30% blend.
• Adding 4mm fibres to untreated pulps increased the throughput by 7.5% at a 10% addition of the bico fibre and by 40% for a 30% addition. 6mm PP-cored fibre additions caused a small deterioration in throughput with this pulp, while 6mm PES-cored fibre gave a slight increase of capacity.
• Higher capacities were obtained when blending 4mm fibres with untreated pulps than by blending 6mm fibres with treated pulps.

Throughputs ranged from a low of 130 kgs/hr/metre (untreated pulp, with 30% of 6mm fibre) to a high of 330kgs/hr/metre (treated pulp with 20% of 4mm fibre) indicating the profound effect of the variables studied. Further work is planned.

Meltblowing Biodegradables

Prof. Dieter Müller of Bremen University re-presented his INTC 2000 paper on melt-blowing biodegradable polymers and extended it to consider applications of PEA and PLA in more detail. Polylactic acid, polyesteramide, polyvinyl alcohol, cellulose diacetate and a polycaprolactam/thermoplastic starch alloy were all meltblown on the 1” extruder at Tandec. Polypropylene was the control. Only PLA and PEA (after adding 3% glycerol) gave fibrous webs like PP, but only PEA gave a nonwoven with usable strength. (PP meltblown was 40 times as strong and 5 times as extensible as the PLA, but only twice as strong and only one fifth as extensible as the PEA.) Neither PVOH, PC/TS nor cellulose diacetate, even with 10% glycerol added, would form fibres. The chart of polymer prices showed PP=0.45, PEA=1.3, PLA=0.75, CA=1.55, and PCL=1.75 and TPS=0.6 c/lb. Prof Müller considered the key properties of PEA to be:
• High strength and extension
• High stiffness cf PP or PS
• High “form constancy” against thermal impact in the 100-140 o C range (ISO 75).
• High impact strength at low temperatures (-30 o C)
• Food contact approval. The polymer is already used in disposable cutlery.
• Conforms to DIN 54900 biodegradability standards.

For comparison, PLA showed:
• High resistance against grease.
• Can be modified to be flexible or stiff.
• Food contact approved.
• Industrially compostable according to ASTM D 5338, but not suitable for home composting.
• Melts between 120 and 170 o C, but a softening point of 55 o C according to EN ISO 306 may be limiting.

In response to questions he revealed that PEA was no longer in commercial production, the only supplier, Bayer ( Leverkusen ), having decided to close the plant as uneconomic in the last few weeks. Bayer were however looking for possible purchasers of the technology. Asked about Eastmans Eastar Bio® biodegradable polymer, he said that also in the last few weeks, samples had been meltblown at Tandec. They were similar to PEA in character showing good processability to give even fabrics with good strength and elasticity. Biodegradation was good and there was some evidence that it disappeared in seawater also.

AUL and K-C

Mark Bolyen of MTS pointed out the short-comings of the absorbency under load test with particular reference to K-C's claim in USP 5147343 that high AUL surprisingly correlated with reduced overnight leakage of diapers. This had been accepted as a valid claim and referenced in #5601542. Mr Bolyen pointed out that AUL was probably OK for SAP QC work but there was no evidence that AUL correlated with diaper performance in use:
• There was no way to pressurise the insult area of a diaper in use.
• Why 3psi? It was the pressure which showed the maximum difference between SAP's in Stan Kellenberger's 1992 patent (#5147343 for K-C).
• Any test which allowed 1 hour to reach equilibrium was silly in the diaper performance context
• The cylinder weight tended to stick in the cylinder cause massive AUL errors.
• Seiving SAP prior to testing (to remove the dust that causes sticking?) does affect the results and is another undesirable procedure.
• Testing polymer alone (vs in pads) was a dubious basis for claims on pad performance.
• Reproducibility between labs testing the same SAP's was poor.
• K-C's claim that weight of SAP used per diaper (3,5 or 7 gms) does not affect overnight leaks - but AUL does - is not borne out by a re-analysis of the data in the patent.

Was this academic? No. K-C were now effectively claiming that use of SAP's with AUL above about 25 in diapers was their invention, thereby restricting further SAP development. The patent is unlikely to be upheld in Europe but could be troublesome in the USA .

Calvin Woodings 3/5/01

IDEA 2001 – Miami Beach: March 27th to 29th IDEA 2001 – Miami Beach: March 27th to 29th

This was a large conference with forty-five papers spread over three days each with three simultaneous sessions. The keynote speech and three of the nine sessions were attended and these are reported below.

Wipes

Shop Towels

Ralph Solarski of Kimberly Clark reviewed the progress in allowing nonwovens to compete on an equal footing with laundered shop-towels in the industrial sector. If a wipe is contaminated with any amount of hazardous material, its disposal in the solid waste stream is governed by EPA regulations (RCRA). Disposal of wipes contaminated with a small amount of acetone for instance, whether nonwoven or woven, must be registered with the EPA, transport must be in sealed containers, specially labelled, in specially licensed vehicles and disposal must be at a licensed site subject to EPA audit. However if the wipe is laundered, the contaminant is deemed to be extracted and disposed of in the liquid waste stream and as such is free of such costly and time-consuming regulations. Because nonwovens are rarely laundered, they face a significant hurdle in competing with the laundered products despite being better suited to the job and cleaner than laundered products at the start. So, in the USA , 85-90% of solvent wiping applications use the laundered shop towel route. INDA is now working with the secondary materials and recycled textiles association (SMART) and with help from the wipe users is lobbying the EPA for change. The laundries on the other hand are fighting the proposed changes, which are broadly as follows:
• All wipes, nonwoven or woven should be subject to RCRA, laundries by implication becoming “disposal sites” to be registered.
• All wipes should be exempt from RCRA if they are stored in sealed containers at the generation site.
• Wipes containing <5gms solvent can be landfilled or incinerated in the normal household waste stream at municipal sites.
• Wipes containing >5gms solvent should be incinerated at municipal sites if sealed in containers for transport and incineration. They should only be landfilled at an EPA licensed site.
• Wipes “dripping” with solvent should not be laundered.

These proposed changes are now being reviewed by interested parties, any comments will be considered and if appropriate incorporated to allow a final set of rules to be published by the end of this year. However INDA now need the industry's support to mount a lobby equal in volume to that of the laundry lobby. Members are encouraged to communicate their support for this rule-change to their senators and congressmen. Nonwovens are in the right here but are running into very strong resistance. Peter Mayberry of INDA would like to hear from anyone who knows their elected representative personally. Disposables, currently a $600million sector, should be able to take a much bigger share of the $1.6 billion wiping market.

Lyocell Wipes

Nick Simpson stepped in to give Hilda Coulsey's paper on Tencel solvent spun rayon in wipes. Acordis has further developed the sled-test for comparing wiping materials and now uses image analysis to quantify any fibrous residues left on the surface. (See also the Dupont paper below). Wipes containing cellulose continue to leave more lint than synthetic fibres, but the synthetics leave more liquid residues. 100% Tencel is the best performing cellulosic and the lint shed can be further reduced by overbonding with 10% latex or by aperturing. Nonwoven applications for Tencel were listed as battery separators, footwear, filters and wipes. In the wipes category, microwavable patient bathing towels and kitchen wipes were the main Tencel applications with baby wet-wipes being at an advanced stage of development.

Air-Laid Wet Wipes

Susan Stansbury updated her Insight 2000 paper on air-laid in wet wipes this time under Georgia Pacific colours. Her breakdown of the air-laid market had 21% going into Femcare, 21% into dry wipes and 20% into wet-wipes. She noted that the arrival of several “just add water” products (e.g. P&G's “Olay” daily facials) would blur the boundary between the wet and dry sectors, because the new dry products contained lotion ingredients which were activated by dipping the dry wipe in water before use.

She continued to position air-laid between wet-laid/latex and card/HE products said they were “good enough” to occupy the middle ground in the wet-wipe market. It was cheaper to make than the premium carded products but had adequate strength, acceptable aesthetics and it could be embossed to create more surface interest and bulk to offset the aperturing advantage of hydroentanglement. Their consumer study showed GPs' air-laid wipes were preferred to wet-laid hydroentangled products. In a section on antimicrobials, she said they were needed to protect wet-wipes from mould-growth in storage, to help clean surfaces of germs and to fight germs on the human body. Ideally they should not cause the evolution of resistant strains of microorganisms.

Clean room wipes

Marshall Outhout of Dupont had, like Acordis, been using a sled-test with image analysis of the wiped surface to quantify wipe performance, in this case focussing on the extremely critical requirements of clean room wipes. He reminded us that the air we were breathing probably contained more than 50,000 particles per cubic foot, and for a class one electronic clean room this had to be reduced to less than one ppcf. Materials entering a clean room had to maintain this standard and had to wipe surfaces without shedding particles. Knitted continuous filament polyester fabrics were currently regarded as the “Cadillac” of clean-room wipes, but wovens, nonwovens and foams were all used. However wipes were currently selected on the basis of their cleanliness without regard to their ability to wipe up fluids cleanly. Typical specifications covered particle shedding, non-volatile residues, ionic content and static generation but did not consider their functionality i.e. absorbency. He had therefore adapted his test to measure particle removal efficiency (PRE), applying a test fluid containing 10 million particles to the surface ahead of the sled, and counting the particles in the residue left behind. Nine commercial clean-room wipes ranging across the entire range of possibilities had been tested. Not surprisingly, wipes that picked up most fluid had the best PRE in this test, and these were not the wipes which had the best rating against the current specifications. Knitted continuous filament polyester came out badly compared with HE lyocell, and wipes with the best “filtration” characteristics (finest fibres) always picked up (trapped) more particles. He concluded that PRE correlates directly with dynamic absorbency, the lyocell wipes being the best in this regard also. He also concluded that inherent cleanliness is less important than the ability to wipe dry: so-called dirty absorbent fabrics leaving far fewer particles behind than the ultra clean non-absorbent ones. In response to questions the particles used were polystyrene latex spheres used to calibrate particle counters, and the polyester wipes had a surface finish to make them hydrophilic. The unasked question of most significance: how relevant is the test fluid to a real clean-room environment?

Food Service Wipes

Bill Vogel of Atlantic Mills updated his INTC paper on food service wipes. In 2001 the National Restaurant Association expected $399bn in sales of 54 billion meals through 844,000 eateries in the USA . 45% of the food dollar would be spent away from home, contributing 4% of GDP and employing 11.3 million people. He said wipes were used in all parts of the restaurant, generally with a bucket of disinfectant and often with a harsh chemical like hypochlorite bleach. Disposables now have about 15 to 25% of the market according to various surveys. They were expected to last more than one day to be competitive with durables. In response to questions he said that the card/latex Handiwipe generally lasted for 1 to 3 days, whereas the newer spunlaced wipes could last 3 to 5 days.

Plenary Session

The INDA awards ceremony

Prizes were as follows:
• Fibre and Raw Materials winner: Eastman with Eastar Bio degradable polyester.
• Machinery and Equipment : Dilo with Hyperpunch elliptical needling. (Rieter-Perfojet Airlace and KT Stacpac were nominated.
• Roll Goods : PTI Armour ballistic protection fabric. (Freudenberg Evolon and K-C's Intrepid bico spunmelt were nominated)
• Short life product : P&G Swiffer. (K-C Little Swimmers and Clopay ? nominated
• Long Life product : Colbond Enka-Grid soil reinforcement
• Entrepreneur : Mogul, the Turkish spunlaid producer (3 lines)
• The lifetime achievement award went to Wayne Hays.

Keynote: 3M Nonwovens

Dr Paul Guehler , 3M's VP of R&D gave the keynote speech on “Nonwovens based Businesses at 3M”. 15% of 3M's $17bn turnover uses nonwoven components, but they are a net buyer of nonwoven roll-goods. They concentrate on small specialised production units making high value niche products, but with an overall goal of converting these niches into “canyons”. Current nonwoven businesses were in tapes, gowns, masks, pharmaceuticals, electronics, light management, reflective signs, highway marking tapes, abrasives, filters and Thinsulate - a blend of melt-blown and staple fibres. One example of a niche that had developed into a major product was their multi-layer film with 50% reflectance and 50% light transmission now used in all laptop and phone displays. He said 3M had been in NW's for 50 years, commencing with a carded acetate product making a packaging ribbon, with respirators and abrasive pads being early products which were still made. More recently, developments of their melt-blowing process had yielded polyurethane dressings, charge-enhancing additives, and finer fibres for better filters. Their Nextel™ flamestop paper was in fact a ceramic nonwoven. They want to capture more of the predicted 7.3% annual growth in nonwovens and plan to create a completely new nonwoven “category” as well as developing more new processes and new products.

Hygiene I & II

Latin American Markets

Rolando Dominguez, Marketing Director of PGI Latin America reviewed opportunities for disposables in Latin America, defined initially as the 21 countries south of Mexico . The region's population had 65% under 35 and only 15% over 50: much younger than other regions. Data credited to John Starr showed the main players to be KC Lao, Grupo P I Mabe, P&G, CMPC, and Absorbmex. Units sold in the region, this time including Mexico were ~14bn diapers, 15bn femcare and 0.4bn AI. Growth in diaper sales of ~8% were expected through 2004, with AI growing at ~15% and Femcare at ~5%. The AI market was however small for both demographic and social reasons. Social change leading to better planning for old age and care of the elderly would be required before this market became really attractive. Mexico had the highest penetration of AI products (16%) followed by Chile (10%) and Argentina (8%). For femcare market penetration, Mexico and Argentina led with 60% each, Chile and Venezuela having 45% each and Brazil 35%. Chile led the diaper market penetration figures with 60% followed by Argentina (55%), and Venezuela and Mexico both on 35%. K-C led the diaper/training pant sector in 2000 in Mexico with a 49% market share, P&G coming third (11%) after PI Mabe (24%). (Absorbmex who created interest in their photo-degradable diaper at Insight 2000 had 7%.) For Latin America as defined, the diaper market shares were K-C (35%), P&G (25%), PI Mabe (18%) with a further 35 converters accounting for the remaining 22%. Recent activity included K-C Lao acquiring Mimo, and Mabe acquiring Drypers. New entrants in 2000 were listed as Papelera Maldonado and Papelera San Francisco in Mexico , Biopapel in Venezuela and CPMC in Chile . 10 new diaper machines, 6 new femcare machines and 3 new AI machines had been installed by independents. Interestingly only Mexico and the Andean Pact countries are using US technology, the rest adopting European. All are about 18 months technologically behind the leaders in US and Europe . In response to questions Mr Dominguez estimated 70% of the femcare market was external, and that the goal of a single Latin American trade bloc would not be reached in the next 10 years.

Internet scare-marketing

Peter Mayberry of INDA described the action being taken to deal with irresponsible Internet scare-marketing in the feminine hygiene sector. The asbestos and dioxin in tampons stories were put out as email gossip by small companies wishing to draw attention to their products – usually 100% cotton tampons with additional “GMO-free” and/or “dioxin-free” claims or implications. There were few if any legal options: no direct slander or libel had occurred, so the action involved working with the FDA and the EPA to make sure internet users had access to the real facts on these government sites. The asbestos story was of course totally and easily refuted. Dioxin was a little harder because judgements of safe exposure levels had to be made. However the EPA were pointing out the ubiquity of dioxin, and the fact that 95% of daily exposure came from eating animal fats. In fact a well known brand of “organic” ice-cream in the USA had been shown to have 2000 times the EPA recommended daily limit. Tampons in comparison, whether made from rayon, cotton or peroxide-bleached 100% GMO-free organic cotton all contained traces of dioxin at the threshold of detection - 0.1 to 1 part per trillion: well within the EPA guidelines. Furthermore numerous respected and independent medical professionals were giving public endorsement to the EPA position. For instance, one was pointing out that tampons are made to absorb not desorb, and the trace of dioxin was not capable of entering the body. Organicessentials.com, one of the three sites mentioned as pushing the “safer” tampons had now altered their site to reflect the EPA position. The other sites mentioned were TerreFemme.com and Naturecare.com. INDA and others now carefully monitored the Internet, and the FDA were carrying out their own dioxin tests on various tampon brands. Mr Mayberry alluded to the European “toxic tampon” scare perpetrated by Greenpeace on the basis of some dubious organo-tin analyses. Greenpeace had now apologised for getting it wrong. (The FDA response can be read at www.fda.gov/cdrh/ocd/tampons.html )

Fabio Zampollo of SSP & Technology ( Italy ) , while present at the exhibition, declined to give his paper on Technology and Future Developments in Hygiene. There were no copies available on the stand either.

Microporous Films

Rick Jezzi of Clopay described their microporous film technology and marketing after a review of the history of diaper development. He positioned microporous technology between melt-blown fabrics and monolithic films for breathability and barrier properties but claimed it was the cheapest. Like the monolithics, it could be laminated to nonwovens, and Clopay were now capable of producing zoned laminates, with a breathable strip down the centre or down the two outside edges of a diaper back. He said breathability had been established in femcare by J&J with “Assure” in 1984, first using hydrophobic tissue (leaked), then meltblown (leaked) and finally with breathable film which worked well. He thought the main opportunity for microporous films would be in AI products where a larger area of the body was subject to occlusion and where the wearer could assess the benefit and decide whether to pay the premium. Here retail would be the main outlet followed by institutional as the purchasing officers realised the benefits arising from improved skin health. Attempts to show the reduced temperature benefits of breathable adult diapers using IR photography had failed, but with sensors in the pad they could show that their films led to diapers being 3-5 o C cooler, and 15-30% RH less humid than standard products. They were clearly more comfortable and would cause less skin hydration. Breathable film use was expected to reach about 240,000 tonnes worldwide by 2004, up from about 140,000 tonnes in 1999. In response to questions, Mr Jezzi thought that breathable film backsheets might also contribute to the ability of the core to pull more fluid away from the skin, but the effect would be small. Diapers could be expected to evolve to become more like normal underwear, and their breathability would be tested by measurements of transepidermal water loss. Why laminate nonwoven to both sides of a microporous film? The inner nonwoven would promote distribution of the fluid over a bigger area of the film, the outer presumably just giving a textile-like character.

Baled Absorbent Core

Juan Carlos Zuhlsdorf of Gevas Packaging and Converting reviewed improvements being made to the baling (as opposed to reeling) of pre-formed absorbents. Using a perforator rather than a slitter to cut to width had solved early problems with low bale stability due to the lack of cohesion between the layers of slit sheets. The layers remained loosely connected until the final pull-off into the converting machinery, and the bales were therefore much more stable. Speeds of 350m/min were now achieved and this gave a run time of 50mins per bale. Up-time was increased because the baling system allowed layers and bales to be spliced together off-line. Tape widths down to half-inch could be handled in this way. His process was fully commercial in femcare and under extended testing for AI. Testing in diapers had commenced. The benefits of more efficient storage and shipping along with reduced materials handling labour c.f. reels were well established.

The Future of Nonwovens?

Fred Crowe, President of BBA's North American Hygiene division chose this, the first anniversary of his involvement in the nonwovens industry, to outline his views on the future of nonwovens in hygiene products. In what was really a business school review of a mature industry with particular emphasis on the merits of supply chain management, there were nevertheless some interesting insights. With reference to the last year he saw hygienic nonwovens as suffering from declining margins, escalating raw materials costs, overcapacity, cannibalisation of products, too many new entrants, reduced barriers to entry, currency fluctuations leading to supplier changes, reluctance to pay for differentiation and a lack of integration in the supply chain. The only redeeming feature was the steadily increasing amount of nonwovens used in each diaper, the 2004 use of nonwoven in backsheet likely to be 40% above the 1999 figure in North America . He observed:
• We can't rely on current markets, products and customers to get us out of the mess.
• The overcapacity will get worse because the lower entry barriers are still allowing new companies to start up with new equipment.
• Rapidly evolving turn-key plant innovations mean that the new equipment outperforms the old and readily takes market share.
• Established producers have to develop new outlets at low prices to survive with second-best kit, thereby depressing the whole market.
• Alternatively they exit hygiene and move into medical or industrial sectors, where the whole process repeats itself.
• Innovation alone won't be enough to balance the market.
• New markets need to be invented.
• Customers must become partners.

He saw a future that was market-driven rather than technology driven, where extremely lean nonwoven manufacturing units with lower-than-ever costs were linked on-line to customers and suppliers allowing instantaneous sharing of all data relevant to increasing the efficiency of the supply chain. This was clearly not good enough for the first questioner who led off with “What is the future for hygienic nonwovens?”

Diaper rash

Dr Bernice Krafchik of Toronto's Hospital for Sick Children outlined the causes of diaper rash and the ways of preventing it. Normal skin was defined by its moisture and fat content, and could be damaged by dehydration (e.g. alcohol in wipes), over-hydration (occlusion), harsh soaps, and perfumes. Damaged skin was prone to dermatitis or psoriasis, the former being caused by diapers, the latter being aggravated by them. Diaper dermatitis came in two forms, irritant where only skin in contact with coverstock becomes inflamed, and candidal where all the skin becomes inflamed by a yeast infection which thrives in the moist conditions. In both cases maceration follows occlusion and allows activated lipases and proteases in the faeces coupled with high pH to further damage the skin. Candida and staph invasion follows readily. The problems were worst for home diapering because cotton products were difficult to clean and rinse properly in the domestic environment. Users of diaper services fared better because the cloths were thoroughly washed and rinsed. Frequent changing of disposable diapers improves the situation further, and the latest superabsorbent diapers can almost completely eliminate the problem provided they are changed often enough. The use of petrolatum on coverstock to protect the skin, and the use of breathable backs to reduce the humidity are both beneficial. How could diapers be improved to further reduce the incidence of diaper rash? The most important next step according to Dr Krafchik was to make them cheaper, and hence more useable in poorer households and more frequently changeable elsewhere. She also mentioned a clinical study about to appear in a paediatric journal showing that Kimberly Clark's new breathable diapers reduced irritant rash by 50% and candidal rash by 60%.

Branding for Roll Goods Maggie Springer (Consultant) made a case for improving business to business marketing by paying more attention to roll-goods branding. A recognisable brand-name was a promise that a set of expectations would be met consistently and as such was as relevant in B2B transactions as in B2C. Her argument was somewhat undermined by her main examples of valuable B2B brands (e.g. Teflon and Pentium) being strong because they were also promoted heavily to consumers, a prohibitively expensive option for most nonwovens producers.

Pre-formed Cores

Kristopher Matula of Buckeye Technologies Inc. expected air-laid usage in femcare to grow by 10.6% (CAGR) to 2004 compared with a 4.5% growth in all femcare sales. Buckeye's offering, the Unicore™ air-laid core had attributes which would enable it to take a large share of this growth:
• It had increasing density and resilience from top to back, allowing rapid acquisition and distribution of fluid while leaving a small stain area on the surface, and better uptake of multiple insults.
• Its multi-bonding coupled with the Stac-Pac compressed bale packaging allowed efficient high-speed conversion.
• Third insult acquisition rate was about 8 times higher than current femcare brands (0.8 mls/sec at 255 gsm).
• Third insult retention (97% for the 255 gsm version) was significantly up on the best femcare competition tested (60% at 300+ gsm)

In diaper cores, a 500 gsm dual layer was giving higher acquisition rate (1.7 ml/sec c.f. 0.5 to 1.25) and similar retention (96%) to the global brand leaders. Fluid distributed through the Unicore™ more completely, covering ~2/3rds of the diaper after 100ml insult and ~9/10ths after 300mls. Much improved SAP retention and softness arose from a “powder gradient structure” obtained by running the SAP in two stripes, allowing the centre and edges of the core strip to be properly sealed. SAP loss of 0.07mgms for the powder gradient structure compared with 4.2mgms for the homogeneous core. Asked why airlaid was still not used in diapers, Mr Matula said that early products did not work as well as Unicore™, and that current products were still too expensive. They had to be made more cheaply and this was where the 50,000 tonne machine would help. Buckeye was also developing new wiping products using the new core technology. An “Engineered scrubber pad” had a surface layer with abrasive particles bonded to it, thereby allowing more efficient cleaning of hard surfaces. Asked if air-laid would be able to challenge HE in European baby-wipes he thought it would be possible to build spun-lace attributes into air-laid. (In private conversation he explained the failure of the air-laid cotton tampon header roll as being due to the fact that the tampon industry wanted to use rayon. Why not use rayon short-cut? It was too expensive compared with staple.)

On-Line Inspection

John Ricardi of Cognex described the development of vision systems to emulate human sight in nonwoven fabric on-line inspection. Their digital video system allowed defects to be photographed, counted, mapped, stored and redisplayed to order on a Windows NT system. Data would be instantly available to all, including customers if they were put on the network. The software recorded the co-ordinates of faults in each roll so that they could be removed on unwind. Nonwoven formation could also be quantified as the coefficient of variation of the shades of gray observed in each pixel. Print outs of the faults in pancakes slit from jumbo rolls could be obtained by entering knife positions. Cognis have installed 35 systems in the last year.

Points from the exhibition.

• Ahlstrom had sample packs of dispersible wet-wipes said to be binder-free HE rayon. This looks close to the process I had envisaged for fibrillated lyocell but they declined to comment on whether or not the rayon was lyocell. Some of the pulp/viscose wet-laid HE fabrics are looking better – this in principle being the best way to incorporate cheaper cellulosics. There was no HE-Trinitex, but I was led to believe it would be coming.
• American Nonwovens were showing latex bonded Tencel at about 60 gsm for a wet-wiping application. It was overall bonded but latex migration had left a soft centre that contributed to bulk and softness.
• Camelot were showing a 200 gsm PET/Fibersorb needlefelt for AI cores and femcare. They also had literature on their fibre metering and dosing equipment, and their “chimney-former” for laying down short fibres.
• Eastex ( China ) were showing their HE fabrics for wet-wipes and provided small travel packs of the wipes said to be made by a close associate.
• Gordian Industries (HK) had bulky, coloured antimicrobial dry-wipes probably made by tack-needling followed by thermal bonding of a spun-dyed fibres.
• Green Bay Nonwovens had a full range of HE fabrics on display including an 83 gsm rayon product reinforced with scrim.
• Hainan Xinlong ( China ) had packs of their HE wet-wipes on display and commented that their $2/pack pricing was purely introductory. They also had absorbable HE Chitosan wound dressings on display.
• Hangzhou Xinhua ( China ) “Double ring” range of HE nonwovens looks good. They claim a wet-wipe capability but had none on the display. They are testing Tencel.
• High Point ( US division of Kao) was offering a chitosan finish to control odour and bacteria on fabrics. (“Be Fresh”)
• Innovent (previously Eldim) were offering melt-blown pilot facilities including a 3D forming capability.
• Micrex were demonstrating “stuffer-box crimping” of HE nonwovens to create bulk by a coarse creping operation.
• Nan Liu Enterprise Co. ( China ) had good looking Fleissner process spun-lace for wipes. They had wet-wipes on display but would not give them away.
• National Nonwovens were showing Suresorb® superabsorbent needlefelts, probably a blend of polyester and/or viscose and superabsorbent fibres. They were intended for morgue use and were in weights of 4 to 14 oz/yd 2 , said to absorb 60 times their own weight. They had a similar product for emergency cooling (just soak and freeze, not necessarily for morgue use!)
• NCRC's new multipurpose nonwoven pilot line is for hire at ~$8000/day for the full spun-melt-HE system . HE only will cost ~$3000/day. The HE unit is from Fliessner.
• Novita ( Poland ) “Specialists in hygiene and wiping” were promoting products from their 1.6m wide Perfojet line and their 4m wide needlepunch line.
• Photon Formosa ( Taiwan ) were displaying perforated polybag ice-packs, not unlike a wet-wipe flow-pack, but containing superabsorbents. Intended use after soak and freeze – meat and fish packing .
• Scimat (division of Crane base in the UK ) has a roll-to-roll grafting process making PP permanently hydrophilic by grafting acrylic acid. The process made separators for NiMH batteries, but could in principle be used for other chemistries and could also be used on tows.
• Spuntech ( Israel ) is using 60-80 tonnes/month of Tencel in hydroentanglement for wet and dry wiping. Their third HE line, originally destined for Shalag Shamir who merged with Spuntech, is now operational.
• Tencel were for the first time offering a truly dull fibre containing 1.2% titania. (Previous maximum, when textile fibres had top priority, was 0.6%). Dtex down to 1.25 was also a first at a nonwoven show.
• Treco Fibematics displayed wiping materials based on most nonwoven technologies, mostly made from manufacturers second grade material, many with viscose. A creped air-laid, seen for the first time on this stand, looked good.
• US Pacific (HK) showed a very coarsely apertured HE dishcloth-type wiping fabric reminiscent of PGI's product. They also had soft hydroentangled viscose cosmetic masks on display.
• Versacore were demonstrating their honeycomb-making machine which produces a semi-rigid pocketed structure from thermoplastic nonwoven ribbons. It was intended for composites use.

©C R Woodings 2001

Nonwovens in Filtration: Stuttgart 6th-7th March 2001

The conference was organised by Filter Media Consulting in co-operation with EDANA. Lutz Bergmann of Filter Media Consulting and Peter Meijer of Fiberweb-BBA Nonwovens chaired the sessions. Paul Dewingaerden of EDANA opened the meeting.

The 2000 Top 10

Karin Bitz, Editor of Nonwovens Industry Magazine listed the top 10 nonwoven industry events of 2000 in reverse order as:
• The forging of partnerships in all segments of the industry.
• Globalisation: the roll-goods producers moving into China , Latin America, Eastern Europe and Turkey .
• The growth of the filtration sector, now a $2bn market. INDA's conference and exhibition last year attracted 2400 visitors.
• The growth of internet marketing
• The growth of web-based commerce.
• Expansion at PGI: their link-up with Vateks in Turkey and with Nanhai in China , the $40m investment at North Little Rock in Miratec hydroentanglement technology.
• Expansion at BBA: the Chinese air-lay line, the acquisitions of Snow Filtration and AQF Technologies.
• Air-laid expansions: Buckeye/Walkisoft and their start-up this spring of the 50,000 tonne air-layer.
• Continued ferocious competition, especially in diapers between P&G and K-C.
• The slower growth of established global markets, leading producers to look to the emerging markets.

With regard to this last key issue and the increasing evidence of overcapacity in some technologies she concluded that the discovery of the next “great new nonwoven application” was now somewhat overdue.

Filters on the Web

Brandon Ost, the CEO of eFiltration Inc reminded us that despite the 54% plunge in the Nasdaq index, internet use was still doubling every 100 days and the Web now hosted 100 million business users. The internet economy accounted for one-fifth of US revenue generated in the last 6 months and globally accounted for $657 billion in sales last year. With many more people and companies researching on-line and buying off-line, e-Commerce sites were already having a much larger influence than was suggested by the actual sales figures. Could a website be set up to market and sell industrial filters? Mr Ost clearly thought so. However, the complexity of the product range and the supply chain, and the need for in-depth product and application knowledge, coupled with extensive after sales support meant that the site would be anything but ordinary. EFiltration had helped a small distributor of industrial air filters to set up a website. Their complete range could be displayed and the software allowed customers to configure complex products on-line and order them at “customer-specific” prices. Combined set-up and annual costs to the filter distributor were around one-third of the costs of a salesperson. For a large filter maker with thousands of SKU's, the only practical approach seemed to be to start quickly with a small investment on a flexible system, which could grow “daily” as new features were required and as new e-business tools were developed.

Nanofibres?

Michael Wehmann of JM Laboratories Europe (soon to be renamed to reflect Nordson's ownership) gave the first of several papers to mention nanofibres. In the quest for ever-finer fibres, JM were working with Hills Inc on modified melt blowing processes including the use of splittable bicomponent technology, and on an electro-spinning process in co-operation with Akron University and NC State. Electro-spinning appeared to be melt-blowing with a high voltage between the die and collector. They were also driving down the fibre size obtainable in melt-blowing by optimising air-plenums, forming boxes and quench air systems. A 120 o (rather than 60 o ) die-tip angle was being used to generate turbulent air-flow at the point of extrusion, this having been shown to allow finer fibres with any given polymer. They were also working with the polymer producers to get the cleaner more consistent resins needed to maintain throughput as fibre size diminished.

Finer Meltblown

One of these producers, Borealis Polymers NV ( Belgium ) took up the story, Nancy Noynaert reviewing the benefits of increasing the melt-flow rate of PP to 1200. In addition to finer melt-blown fibres, the new pelletised polymer allows improved electrostatic charging due to reduced peroxide content, better melt, process and fibre uniformity, longer die life, and FDA appoval. It also allows a given level of web air-permeability to be achieved with lower process air volumes. The finer fibres produced were said to allow 95% of all particles below 0.1micron in diameter to be retained on the melt-blown filter. Ms Noynaert also reviewed the current market for melt-blown nonwovens. 120,000 tonnes of meltblown were produced globally last year, 97,000 tonnes of this being PP. Meltblowns were consumed in filtration (26%) hygiene (46%) and oil sorbents (28%) Europe used 37,500 tonnes in 2000 and was expected to require 50-55,000 tonnes in 2004. Asia used 18,400 tonnes and the Americas used 47,100 tonnes.

Melt- versus solution-blown implants

Dr Martin Dauner of ITV Denkendorf compared melt-blowing with solution spinning routes to microfibres, but only in the context of their use with resorbable fibres for medical implants. Both technologies use similar equipment, with a solution of polymer replacing the melt in the case of solution spinning. The dilute solution of polymer is blown onto the former where it bonds due to incomplete removal of the solvent. (A J&J electrostatic spraying process was also mentioned: EP 0095940 and GB 2189758.) The melt-blown process used by ITV has 15 holes and is based on an NC State development. Polymers tested in both processes included poly-l-lactic acid, the d,l copolymer, and a segmented polyurethane. Poly glycolic acid could only be meltblown. Fibres and pore sizes tended to be finer and more uniform with solution spinning. The fact that on average the solvent route gave fibres about one-tenth of the diameter of the meltblown route was partly due to the solutions extruded containing only 2-15% of solids. Illustrations not included in the written text showed the spray-forming of tubular tracheal implants on shaped mandrels, and the creation of an artificial ear by spray forming the shape and then growing skin cells on the resulting fabric. Comparisons of MB, SS, and an Electrostatic Spinning process showed ES with an undefined polymer to give the finest, most regular fibres (down to 0.01 micron diameter with up to 3x variation), but the resulting fabrics were not self supporting. Solution spinning gave fibres down to 0.1 micron with up to 100x variation, while melt blowing gave down to 1 micron fibres with up to 100x variation. In private conversation Mr Dauner agreed to forward a selection of the many slides not included in the written paper. Asked about cellulosics in implants he said the body could not absorb cellulose and always tried to reject it.

Multi-layered Media and Markets

Kyung-Ju Choi of AAF International ( USA ) described experiments to optimise the filtration performance of multi-layered media and provided some data on the world air-filtration market that was not included in the written paper. Multiple layers do not perform as well as calculated from filtration data on the individual layers. He concluded that the layers must be separated for best results. With regard to the market he estimated world air-filter sales to be $826million with the heating, ventilation and air-conditioning (HVAC) filters accounting for 52% of this. Bag House filters on industrial processes were the second biggest category with 24%, automotive was next (cabin-air 6% and engine air 5%). 8% were respirators and face-masks, 3% vacuum cleaner bags and 2% were ultra and high efficiency particulate air filters. The USA used 39% of the total, Europe 33% and Asia 23%. Melt blowing and needling were the growth technologies, wet-lay was declining.

Naturally charged filters

Bernard Drouin of Texel Inc ( Canada ) described how their triboelectric filter (Tribo™) complemented the other routes to efficient electrostatic removal of submicron particles from air streams. Particles below 2.5 microns account for very little inhaled mass but represent 99.5% of the total number of particles inhaled. These are hard to filter conventionally, but can be collected on electrostatically charged surfaces. Charged fibres can be obtained by induction (extruding polymer in an electric field) or by corona discharge treatment of a fibrous web or, as anyone who has worn or walked on synthetic polymers knows, by friction between triboelectrically dissimilar materials. Texel has discovered and patented a blend of polypropylene and polymetaphenylene isophthamide fibres (PCJ/CA 9800470) which produces a large and stable permanent electrostatic charge. In comparison with another well known triboelectric blend (50/50 PP/Modacrylic fibre) the Tribo™ blend with only 25% of the expensive fibre gave better particle retention with less decay over time at a 25% lower air resistance.

Nanofibres!

Nigel Walker of Technical Fibre Products ( UK ) gave the Shrikant Awasthi (Hitco Carbon Composites Inc.) paper on carbon nanofiber-based filter media. TFP has collaborated with Hitco to produce wet-laid filters from carbon nanofibres bonded to standard chopped carbon fibre. The nanofibres are unrelated to the recently discovered “Buckytubes” and are already produced on an “industrial” scale by growing them in a burning gas (e.g. acetylene) stream. They appear as soot, but at high magnification they are revealed as a crimped or spiral fibrous structure with diameters in the 0.1 to 0.2 micron range. When wet laid with regular carbon fibre they can produce filters with the particle removal efficiency of membranes but at 35 times the permeability of a PVDF membrane of similar micron rating. Applications under development include clarifying beers and fruit juices (replacing diatomaceous earth) and the microfiltration of industrial process and waste waters.

Bio-soluble glass fibre

Johns-Manville has developed a glass fibre which is classed as no more than an irritant in the latest European air-filter regulations. Foster Harding explained that this has been achieved by optimising the formulation to increase bio-solubility without affecting product performance (USP 5945360). High silica and low aluminium oxide content appear to the key changes. EU biopersistence testing showed that after rats breathed airborne 902 glass fibres for 5 days, 50% of inhaled fibres longer than 20 microns cleared in 6.8 days. Since the test threshold between “irritant” and “carcinogen” is 10 days, the new fibre gets into the irritant category. In response to questions the new glass fibre was said to be unsuitable for wet-laying. While finer polyester fibres were challenging glass in some markets, Mr Harding said that there is little comparable data on the effects of synthetic fibres in lungs, the crucial “injection” studies never having been done.

Molecular contamination

The semiconductor industry has successfully removed particulate contamination from clean-rooms by using HEPA/ULPA filters, so emphasis is now shifting to control of molecular contaminants. Matthew Middlebrooks of AQF Technologies/BBA Nonwovens ( USA ) listed the problem molecules as Acids and Bases (electron acceptors and donors), Condensables (substances which could condense on a clean surface) and Dopants (elements used to modify the semiconductor properties). AQF's active carbon-loaded through-air bonded bico-fibre nonwovens were capable of absorbing examples of all of these substances. Acids were represented by sulphur dioxide and hydrogen chloride, Bases by ammonia, Condensables by toluene and Dopants by trimethyl phosphate and boron trifluoride. Acid or base adsorption could be enhanced by pre-impregnating the carbon with the bases or acids respectively, although in both cases the condensables and dopants absorption decreased. Longer term, Mr Middlebrooks foresaw the technology being used to control odours in cars and in hotel and airport HVAC systems. (Substituting SAP granules for the carbon would make an excellent absorbent)

Engine filtration

Robert Murphy of Hollingsworth and Vose ( USA ) compared advances in engine filtration, US versus Europe . In Europe, filter lives were being extended past 60,000km (air) and 30,000km (oil) as part of the attempt to keep motoring affordable in a high tax, high gas-price environment. Frequent servicing is however common in the USA and higher efficiency filters have been developed in preference to longer-lasting ones. Europe continues to prefer the low cost phenolic resin bonded filters despite the need for curing and the associated formaldehyde emission. In the USA , solvent-based advanced-cure resins already obviate the need for curing, reduce the time-in-process and protect the users from future capital costs to upgrade curing ovens for environmental compliance. Mr Murphy argued that the advanced cure system would inevitably replace the phenolics as environmental regulations tightened and the increasingly global motor industry demanded identical filters wherever they were fitted. Other developments to note: the gasketless Japanese filters that seal through compressed filter-media, and the all-plastic European Eco oil-filter that can be incinerated whole.

Developing engines to meet ever-reducing emission targets requires radical redesign of both petrol and diesel engines. For diesel, a key step is the use of direct fuel injection through a common rail at very high pressures, and for this the fuel needs to be filtered to remove particles above 2 microns at very high efficiency. Roberto Forna reported that Ahlstrom has achieved this by laminating a meltblown polyester nonwoven upstream of a conventional phenolic coated woodpulp filter paper. The new composite media holds 5 times the contaminant and has an initial efficiency of 90% for 2 micron particles.

Hot-gas filtration I

Control of particulate emissions from incinerators involves the use of cyclones, electrostatic precipitators, wet-scrubbers and fabric filters. Andrew Startin of Madison Filter Ltd. ( UK ) argued that their low-density ceramic fibre cartridge filters offer some significant benefits over fabric filters where the gas stream is at elevated temperatures and where consistent low emissions are mandated. Data was provided from installations of ceramic filters in clinical and chemical waste incinerators where sodium bicarbonate sorbent was added to the gas stream to control acids. They were also being tested by Peugeot as filters on diesel exhausts where the operating temperature was 700-800 0 C.

In a second paper from Madison Filter, Richard Lydon explained how their new Tuftex™ filters are coated to improve abrasion resistance and cake release. The polymer coating is supplied on a release paper and attached to a polyester or polypropylene needlefelt filter through a nip roll. The polymer reticulates in a controlled manner during curing to leave a tough porous surface which appeared to be about 50% covered in film. This nearly doubled the Martindale abrasion resistance and stops any fibrillation if the substrate was PP. In response to questions the coating would double the cost of the filter but would more than double its useful life.

It's an ill wind…

Karl Ott of BASF ( Germany ) gave a remarkably candid account of the “miserable” launch failure of their Basofil™ flame resistant melamine fibre in hot-gas filtration. Having in retrospect chosen the wrong partner, the first trials on this relatively weak fibre were conducted on needlefelt bag-house filters without scrim reinforcement and after a singeing process which had predictably little effect on improving its surface. Their filter-producing partner turned out to be more interested in establishing business for his other filters within BASF than developing Basofil™ and while Mr Ott did not say so, we guessed he failed at this objective also. Convinced of the merits of Basofil™, made “from a condensation reaction of methylol to form a 3D structure”, BASF reanalysed the market at targeted the customers of the leading supplier of aramids. Data from recent bag-house trials at Brox Industries asphalt plant and at LTV steel in the USA showed long filter lives, low pressure drops and excellent emission values compared with the aramid controls. In concluding Mr Ott commented that one of the biggest factors in the successful relaunch was a predictably unfavourable comparison with aramid in the competitor's brochure. The fact that the market leader found Basofil™ worthy of comparison with his aramid created intense interest in the new fibre.

Pleated bags

As particle emission regulations tighten the need to fit more filter area into existing bag-houses increases. Michael Konesky of Southern Felt Co. Inc. ( USA ) described how their pleated filter elements - Pleatlox™ - could be retrofitted to older installations to increase their capacity. In addition to the increased area obtained by pleating the cylindrical filters, the new bags could be cleaned at lower pressures and exhibited reduced abrasion damage.

Hot gas filtration II

Holga Blaha of BWF Textil GmbH and Co. KG ( Germany ) reviewed the choices available for removing dust from power station flue gases. The fibres to consider were acrylic, polyphenylenesulphide, polyimide and PTFE. However the filter fabrics would need surface treatments designed to suit the nature of the dust being removed. Singed surfaces were appropriate for non-agglomerating dusts whereas an agglomerating dust would need a glazed filter surface. PTFE coating and even impregnation would be needed for protection against chemicals, sparks and humidity. For instance, their Needlona® PAN fibre filter impregnated with fluorocarbon would give a 3 year life in a combined heat and power plant with flue gas desulphurisation after spray absorbtion whereas the more expensive polyphenylene sulphide felt with a microporous coating would last for 6 years in the same process.

Surface or in-depth?

Pulse cleaning of bag filters causes a peak in emissions to atmosphere associated with finesbeing dislodged from the depth of the filter and the need for a new cake to form on the surface prior to full efficiency being regained. One solution to this, proposed by Klaus Schumann of Albany International Inc (France) was to increase surface filtration (over depth filtration) by laminating a PTFE membrane or microfibre web to the surface of the needlefelt. Compared with a 1.7 dtex round fibre, a fully-split 16 segment pie-fibre would give 10 times the surface area. Furthermore when the PA and PES polymers separate they generate a natural electostatic charge.

Filtering fumes

Günter Weitz of Jacob Handte and Co GmbH ( Germany ) showed SEM's of the welding “fume” from laser welding and cutting of steel. This dust of submicron (~0.2) spheres of metal oxide blinds almost any filter unit very quickly and can be ignited by sparks from the laser process. A laser cutter for steel plate can generate about 100 kgs/day of such dust, so designing filters for these machines represents a real challenge to the filter producer. The solution employed by Handte involved a PTFE membrane on a PES bico needlefelt, following a spark-precipitator cyclone. The unit is fully automatic, self-cleaning, maintenance free and gives long filter lives.

Waste water filters

• Plate and frame filters clothed with textiles were first developed in 1830 for filtering liquid effluent from the ceramics industry. Fully automatic versions of these are still the main filter type for sewage sludge and industrial process and waste waters. Hubertus Schütt of Junker Filter GmbH reviewed the types of cloths and membranes now available. He showed how the use of membranes in filter presses now offers the best solution to industrial waste water cleaning by reference to trials at a Hoechst AG plant.

Calvin Woodings 14/3/01