Tuesday, 30 March 2004

Nonwoven Technology Conference - Sorrento March 8th -11th 2004

Marketing Technology Services European conference once again concentrated on air lay technology, opening as before with Jim Hanson’s short course on absorbent products which continues to attract the full range of industry talent from new starters to CEO’s. Around 200 delegates stayed at the Hilton overlooking a showery Sorrento, a snow-capped Vesuvius providing a spectacular backdrop.

The air-laid industry at the cross-roads

Ralf Hovelmann, General Manager of Concert GmbH discussed the problems being faced by the air-laid producers since the massive capacity expansion.

  • Between 1998 and 2002 capacity had risen from 270,000 to 400,000 tpa but the expected large increase in sales into diapers had not occurred.
  • Femcare and wipes were still the main markets for air-laid, European deliveries being 65% femcare, 10% hygiene wipes, 7% industrial wipes, 11% table products and 3.4% incontinence products.
  • Capacity utilisation was at 72% in 2004 and expected to rise to 78% next year.
  • Potential growth areas were cigarette filters, repulpable boxes, blood transport packs, transdermal patches, filters, and dessicants. High modulus air-laid products were now possible.

Mr Hovelmann said Concert had closed the South Carolina plant and expected this to be a sufficient capacity-correction. He did not know what Georgia Pacific intended to do with the old Fort James operation, but some consolidation within the industry was essential. Air-lay was at a fork in the road. None of the current producers could supply the requirements of a major diaper producer should they decide to switch. They must either consolidate or form partnerships with major customers. Only then would it be possible to open up major new markets.

Ason-Neumag, 4DG, Nanoval and now M&J

Anders Moller described how the recently purchased M&J Fibretech would complement the other nonwoven technologies the Saurer Group had acquired recently i.e. Ason, Nanoval and 4 DG fibres. Saurer with a €1.8bn turnover comprised Allma (twisting machines), Barmag (spinning and textile machines), Neumag (fibre spinning machines), Schlafhorst (automatic yarn winders), Zinser (cotton spinning machines), Volkmann (yarn processing) and Melco (embroidery).

  • In January this year they opened a new nonwoven R&D centre with an Ason-Neumag spunbond line designed to switch polymers without rebuilding. Fibre deniers between 0.5 and 8 can be spun into fabrics of 10 to 150 gsm from PP, PE, PET, PLA, PA6 and PU. Meltflow rates from 20 to 350 can be handled. The PET can be spun at 8000m/min, the high speed being achieved by use of a short air gap.
  • They are expecting polyester prices to fall below polypropylene as the massive Chinese capacity expansion comes on stream, so spunbond lines capable of switching PP<>PET “on the run” will be in demand.
  • They have acquired a licence for the 4DG fibre in spunbonding from Clemson University whose patents originally came from Eastman and P&G.
  • Nanoval uses a spunbond polymer grade (cheaper than meltblown) to make continuous microfibres through a Laval nozzle with high velocity, non-turbulent cold air to “explode” each filament into a cluster of microfibres.
  • They are installing the first 1.2 meter wide Nanoval head on the spunbond line to make spunbond/Nanoval laminates. Because the Nanoval layer is strong, it does not need the protective extra layer of spunbond required by the meltblown in an SMS structure. Output per hole is 10 times that of meltblown, but because Nanoval uses wider spaced holes, output per meter is currently only double that of meltblown (between 70 and 140 kgs/hr/meter). They expect the system to be commercially available in 2005.

Mr Moller concluded with a conceptual multilayer absorbent laminate made on one machine: a spunbond topsheet, a spunbond 4DG acquisition layer, an M&J pulp/SAP core, a Nanoval barrier layer and spunbond PP/PE bico textile backsheet.

In response to questions, the new spunbond system would spin PP at 6000m/min, PE at 2500-3000 m/min and a PE/PET bico at 8000m/min.

The better economics of the Nanoval approach to microfibres would cut the cost of barrier fabrics dramatically.

A new air-lay machine supplier

Alessandro Celli, Nonwovens Director of A.Celli Nonwovens S.p.A described the philosophy behind their recent development of an air-lay machine to complement their winder business. Celli’s historical core business was the supply of turnkey wet-laid tissue machines up to 5.6 meters wide and running at 1800 m/min. Supplying winders to the nonwovens industry was a side-line, but they had established themselves in this market and felt their pulp knowledge and laying skills could be exploited in the air-lay sector.

Celli Wingformer pilot line

  • The “Wingformer” air-lay machine uses an innovative process which does not copy any existing technology.
  • The fibre distribution system is based on R&D and mathematical modelling at the University of Pisa and achieves better integration of electronics, software, and mechanics than others.
  • They feel there is a need for more sturdily built equipment and their experience with tissue machines allows them to provide this.
  • They built 2 formers during 2002, the smaller 1 m wide unit being installed during 2003 in the new Rieter Perfojet nonwoven pilot plant to allow the development of spunlaid/air-laid/spunlace composites.
  • The larger commercial line is likely to be installed in the next 3 months.
  • After 8 months testing up to March 2004 it has proved capable of high 3D uniformity with both treated and untreated pulps due to its unique wings in the forming zone.
  • On treated pulps it has achieved 450 kgs/hr/m throughput.

Photos of the former now at Rieter Perfojet suggest that the Wingformer abandons the flour-sifter principle of the DanWeb and M&J systems in favour of pre-dispersion of the pulp in air prior to forming the sheet from a headbox onto a wire.

A new source of air lay technology

Alexander Maksimow and Kilian Saueressig of the Airlaid Alliance described how this new company had been formed to licence airlaid lines based on McAirlaid’s proprietary bonding technology. Their Supercore® laminate was 100% superabsorbent sandwiched between two layers of hydrogen bonded 100% woodpulp, and point-bond calendered to fix the whole structure together. The use of 100% woodpulp layers maximised the absorbency and wicking compared with either latex or thermal bonding and therefore allowed fluid to spread farther and faster than in cores using these bonding agents. The absence of bonding reduced costs to 80% of a conventional core and Mr Maksimow believed that further optimisation would achieve a 60% cost target. Additional claims made were:

  • No gel blocking occurs even with 100% SAP in the centre
  • Zero rewet “even after the addition of an extra 50 mls fluid”
  • Satisfactory core integrity.

The Airlaid Alliance is primarily interested in selling the “knowledge package”, not in building the machinery.

Hydroentangled air-laid composites

Thomas Fechter of Fleissner used the latest EDANA statistics to show that thermal bonding was the most used staple nonwoven bonding method (174,000 tonnes in 2002) but was in decline, while hydroentanglement had shown double-digit growth to 134,000 tonnes.

His World nonwoven production statistics showed :

  • North America 1.2 million tonnes
  • W.Europe 1.1 million tonnes
  • Asia Pacific 0.64 million tonnes 11% Growth
  • Japan 0.34 million tonnes
  • Latin America 0.24 million tonnes 10% Growth
  • Middle East 0.17 million tonnes 15.5 % Growth
  • ROW 0.16 million tonnes 10.5% Growth

The growth figures above were for 2001-2006 and based on INDA estimates, where NA, WE and Japan were combined to average 6% growth. Production in China, presumably included in the above Asia-Pacific data, reached 480,000 tonnes in 2002 having grown at an average rate of 23% for at least a decade.

  • In 2006, he expected to see 2,632,000 tonnes of spunlaid, 2,229,000 tonnes of carded, 567,000 tonnes of airlaid, and 202,000 tonnes of wetlaid, with carded growing fastest, followed by spunlaid, airlaid and wetlaid.
  • Within Carding, spunlacing would grow fastest to command 16% of the total by 2006 (up from 9% in 1996), the combined latex/thermal bond share declining to 31% (from 39% in 1991). Needlepunching was static at 53%.
  • Chinese expansions between 1999 and 2002 were 500% for airlaid, 175% for carded/spunlace, 130% for spunbond, 90% for carded/thermal, and 40% for carded/needled. Carded/latex declined. Wetlaying had expanded 30%.

Mr Fechter thought the ideal nonwoven would have the strength of spunbond, the absorbency of airlaid and the softness of spunlace. He also thought that of all the processes, only spunlace could be developed to provide all three attributes in the same material. To further improve absorbency and strength simultaneously he proposed a polyester/pulp/polyester sandwich with a structured surface to further enhance bulk and softness. If the polyester layers were on-line spunbonds, then a 35,000 tonne line would be possible and this would yield fabric at 65% of the cost of current polyester/viscose staple products on a 12,000 tpy/line. Furthermore it would be thicker and more absorbent than current wipes.

In response to questions, Mr Fechter said spunlace production speeds were currently around 200-250m/min. Fleissner had tried spunlacing with air-jets: it works but the energy transfer levels are (unsurprisingly) low. What levels of pulp-loss could be expected when bonding the laminates? Low, if a high grade pulp were used.

The Honshu air former

Mr Setsuo Toyoshima of Oji-Kinocloth described what was once known as the Honshu airlay process and its use to make the current “BK” and “TDS” low density air-laid products.

The BK process sandwiched air-laid pulp between two thin (~2 gsm) skins of ~1.5inch fibres prior to latex bonding. The finished product had a low density core with soft surfaces giving much better strength and integrity. Its main market is the Oshibori hot-towel, followed by cooking papers, soup filters, oil removal pads, food freezing wraps, fish/meat packs and kitchen wipes. SAP and/or bico short-cut could be added to the pulp layer, in which case food packing, femcare cores and inco-pad cores were the target uses.

The TDS process made high void volume products up to 3500 gsm in basis weight using the same Honshu formers, but here the surfaces were readymade nonwovens or tissues fed into the machine from unwind stands. Core densities of 0.05 gms/cc were typical and the thicker products were die-cut into the finished product shapes. The very high wicking rates achieved by these 3D structures led to applications in volatalising room air-fresheners while the low density allowed its use as a cushion layer in packaging and in wallpaper.

In response to questions, Mr Toyoshima said they were trying the BK process on 100% synthetics. Softwood pulp was preferred for both TDS and BK materials.

A new hydroentangled air-lay supplier

Domenico Milesi of Main S.p.A. compared their business plan with reality after 3 years of operating the air-laid plant in Southern Italy. Table napkins, wet wipes, femcare cores and “miscellaneous” were to be the main applications. “Miscellaneous” required very flexible equipment and this they had installed.

  • Their first applications were food-tray absorbents, packaging, panty liners and other hygiene products.
  • Now, femcare and wet wipe applications were in difficulty due to lack of growth and competition from spun-lace.
  • The panty liner market offered some relief, but these needed local manufacture in the countries where growth was to be expected.
  • Preformed diaper cores were still years away (inadequate quality/cost benefit).
  • The food pad market has been good, and here new developments will lead to further growth.
  • Similarly in wipes for domestic use, new needs are emerging.

Unfortunately, pulp air-lay looks unlikely to meet those needs so Main SpA have decided to add a spunlacing capability to their existing line rather than doubling their capacity. To do this they are collaborating with ORSA in the “ORMA” venture, which begins production next month. He explained that increasing the strength of pulp airlay by using more bico fibre (€2.5/kg) was expensive compared with using PES (€1.2/kg), so carding PES and using it to reinforce pulp would give a similar priced product with even better properties. What products would be targeted on the new system?

  • Impregnated personal care wipes (ship dry/use wet, only the central pulp layer would carry the dry-powder ingredient)
  • Dedicated cleaning wipes of the Swiffer variety.
  • Dedicated industrial wipes e.g. lint-free products for the printing industry.
  • 2-sided wipes: abrasive – soft for kitchen use.

Asked if filters would be a possibility if 100% synthetic fibres were used, Mr Milesi thought not. They would be too expensive.

Small-scale air-lay

Henning Skov-Jensen of M&J Fibretech illustrated how small air-lay lines could make high value products profitably. Wound-care products from SCA Molnlycke, male inco-pouches from Conveen Colorplast, carbon powder and fibre blends with woodpulp for filters, and fuel-cell membranes were examples of commercial successes. At the other end of the scale, they now had an air-lay head capable of 2.5 tonnes/hr/meter for a 100,000 tpy diaper core machine. Asked about powder handling capabilities, Mr Jensen said they could do 80% SAP/20% Pulp mixtures, but 35% SAP seemed to be optimum for an air-laid core.

Thin air-laid cores

John Tharpe of R&L Engineering reviewed a method of making thin preformed cores using air-laid technology. He pointed out that since the core forming methods had been developed for one piece diapers, pulp usage per diaper had fallen from 60 gms to 12 gms, implying that a better method of core making must now be possible.

He had tested a variety of ways of converting air-laid pulp/SAP sheets into cores and favoured Z-folding the two edges followed by creating what looked like primitive stand-up leg-gathers from the top edges of the core. These final origami-like folds created a target area below the coverstock and tended to raise up as they got wet, thereby separating the topsheet from the core. He argued that this meant an ADL was not required giving a cost saving that allowed this approach to slightly undercut the on-line core forming methods.

The folding idea avoided prior Z-fold art. The hammer-mill, drum former and SAP units of a conventional diaper line could be replaced with an unwinder for the airlaid, and a Z-folder. He thought this would run at 1000 diapers/min and realise $0.5million capital cost savings per line. (This approach was proposed by Jim Hanson several years ago).

Pre-formed diaper cores

Rich Chapas (Consultant) listed the reasons why preformed cores had failed:

  • Logistical problems associated with low run-time and frequent roll changes
  • The volume of fluid to be absorbed was greater – therefore thicker products were needed.
  • Some diapers needed shaped pads.
  • No clear benefits to the consumer had emerged from all the testing.
  • No clear cost advantage for the manufacturers had emerged.

The advantages of pre-forming over the in-line forming systems now in use were clearly insufficient:

  • Lower capital, energy and maintenance
  • Greater flexibility of material use
  • Multi-layering possible with a wide range of densities
  • Lower waste, improved quality, easy start ups

Mr Chapas thought that diaper performance had been improved so dramatically by the use of leg cuffs and acquisition/distribution layers that the clear technical superiority of the pre-formed core was undetectable in use.

For the future, new materials such as Wellman’s porous polyester fibre (in cross-sectional view this looks like a tubular sponge) and Lysac’s bio-based SAP would improve core design. The Wellman fibre showed high absorbency and rapid wicking compared with standard polyester. Lysac’s SAP absorbency was higher due to it being as absorbent of saline as it was of distilled water, giving double the free-swell capacity and treble the centrifuge retention capacity of conventional SAP. However new technologies such as Tyco’s use of cellulose acetate tow as SAP carrier in a pulp-free core, and new absorbent foams will have to be taken into account.

Better wet-wipes machinery

Alessandro D’Andrea of Fameccanica Data S.p.A considered the problems of designing wet-wipe production machinery to produce a basic range of wet-wipes using 2 different nonwovens and 2 different liquids to make economy, mid-range and high-quality wipes. One of the fabrics would have to be soft, and one of the liquids would have to be creamy for the high quality fabric, the opposite being the case for the economy version.

The differing frictional regimes created by these combinations meant differing levels of overlap in folding to get the right pop-up characteristics for the consumer. The differing overlaps meant differing folded widths and hence differing flow-pack sizes and differing stacking and pallet characteristics. Fameccanica had solved these problems by introducing the new “W-fold” as an alternative to the traditional folding patterns, all of which gave width changes as overlap levels were altered.

Unwind problems were the greatest cause of efficiency losses. Mr D’Andrea considered 4 possible unwind configurations:

  • 10 individual reels – manual splicing
  • 20 individual reels – manual splicing
  • 1 Jumbo Roll slit on-line to 10 lanes – manual splicing
  • 2 half-Jumbo rolls slit to 5 lanes each, with automatic splicing.

Efficiency measurements increased from 76.4% for Option 1, through 79.9% and 81.2% to 99.8% for Option 4.

Many factors contribute to the consumer’s perception of value when using wet-wipes, the most important being the appearance and thickness of the fabric. Consumer panel studies showed that for thickness increases ranging from 10% to 60%, the acceptable price increase was 3% to 20%, roughly a third of the thickness increase. So, Fameccanica now offer on-line embossing to create extra bulk and distinctiveness in the wipes produced. This removes the need to buy the more costly embossed nonwovens and provides more flexibility to the smaller producers.

Asked if their machines would cope with 2-sided wipes, one side harsh, the other soft, Mr D’Andrea said they would, but he would recommend separate wetting stations for each side.

Flushability review

Calvin Woodings (Consultant) reviewed flushable disposables development drawing on work carried out in Courtaulds Research and on the recent sharp increase in US flushability patenting.

Disposal of disposables in the liquid waste stream where the sewage infrastructure could transport the waste to aerobic and anaerobic biodegradation units would be cleaner and more energy efficient than landfilling. For this to be possible, disposables would have to be designed to be processed down this route, and to date this has proved difficult without sacrificing some of their convenience.

By using several of the newer nonwoven technologies in combination, the development of true flushables was now looking more feasible:

  • Laying pulp reinforced with short biodegradable man-made fibres on air- or wet-lay systems.
  • Low-pressure hydroentanglement to increase the strength temporarily. (hydrodisentanglement occurs later in turbulent water).
  • Film/fibre laminates which are waterproof when wetted from one side yet dispersible when wetted from both.
  • Ion-sensitive binders to increase wet-strength.
  • Blends of polyethylene oxide and polyethylene to make fibres, spunbonds and films with varying degrees of absorbency and solubility.

Tissue market overview

Andrew Battista of RISI (part of Paperloop) reviewed the tissue market and considered how its trends could affect the nonwovens industry.

Tissue Machine Start-ups

  • Tissue demand continued to rise and was predicted to reach 7 million tonnes in 2005 in North America compared with 5.5 million tonnes in 1995.
  • In Europe the demand was growing faster from 4 million tonnes in 1995, to 5.7 million tonnes in 2005.
  • Compared with the paper industry as a whole these were healthy figures considering graphic papers (newsprint etc) had shown a 15% decline.
  • Tissue consumption growth remained strongest in Latin America (5.4%) and Asia (5%) compared with W. Europe’s 3.2% and North America’s 2.1%.
  • Capacity expansions were broadly matching these figures, with 540,000 additional tonnes coming on stream in North America, 600,000 tonnes in W Europe, 370,000 tonnes in Latin America and 947,000 tonnes in Asia (2003-2005).
  • Worldwide, a million tonnes of new capacity would be added each year for the next three years and this would exceed the expected demand growth.
  • From the nonwoven industries viewpoint, pulp prices could be expected to increase through 2005, from around $500/t to ~$700/t.
  • There would be enormous cost pressure on tissue producers worldwide, and tissue rices could be expected to rise by 5-6% during this summer.

Microporous film development

Rick Jezzi of Clopay described monolithic breathable films as typically a copolyester film capable of absorbing moisture on one side and evaporating it from the other. These are commercial but at $3/lb they are too costly for disposables. Microporous breathable films are thin open-celled foams, the pores of which are generally small enough to prevent the passage of liquid water, but large enough to allow vapour through. Polyethylene (any type) could be filled (>40%) with fine particles, typically 0.1 to 5 micron calcium carbonate, coated to improve dispersion and stretched after extrusion to elongate the holes created by the particles.

MD stretching was most common and this was adjusted to give an average 1.5 micron pore size. Unfortunately the pore size varied quite a bit and it was possible to get some “spotting” due to tiny amounts of liquid breakthrough.

A better process involved interdigitating rollers (“ring rolling”) which stretched the film over small areas in the cross direction while also applying MD stretch. This process gives pores around 0.25 microns with much less variability and zero liquid leakage. If PP film is used, larger pores are obtained from the same filler size and stretching process.

Bicomponent spunbond and meltblown die technology

Mark Snider of Nordson described work aimed at optimising quality from their 1.2m wide pilot spunbond line. Variations in air-flow of up to 10% can occur and variations in temperature of 36 0C were discovered by thermal imaging. A new “coat-hanger” polymer distribution system and the use of electrical rather than oil heating of the spinnerette gave a 60% improvement in the regularity of 17 gsm fabric production.

Asked if his system would handle PLA resins, Mr Snider said confidential development work was in progress.