Saturday, 30 October 2004

Notes from the Insight Conference – Austin: 10-14th October 2004

The oil really will run out

Ed Thomas, the R&D VP of BBA Fiberweb provided a wake-up call. Simple arithmetic showed that with current oil consumption at 28 billion barrels/day and rising, and with only a trillion barrels of known reserves, it would run out by 2040. Cheap polypropylene, the workhorse raw material of the nonwovens industry will be extinct long before then because propane/propylene will be more valuable in other uses. 93% of oil is used to provide fuel for transport and heating, only 7% going to petrochemicals.

World Oil Production 1925 -2125: The Hubbert Curve

World Oil Production 1925-2125: The Hubbert Curve

PP prices, up 25% this year and now at ~60c/lb would continue to rise and yet PP nonwovens producers were finding it hard to pass on their rising costs. With 2 cents of nonwovens in the average 20cent diaper the balance of profit sharing was clearly unfavourable to the PP producers. Resin suppliers are reluctant to reinvest despite the high price. Shell and BASF were selling off Basell, and BP withdrawing from PP production. There was even talk of mining landfills for PP to recycle.

The consumer will soon see the logic of renewable and biodegradable materials and the demand for such materials will increase. Plant materials either used directly (cotton, hemp, kenaf) or indirectly as rayon or vegetation-to-plastics processes (PLA) will be more widely used. Melt-spun assets will need to work with a variety of new polymers.

Asked about PLA, Dr Thomas found it interesting but limited by price. Its future would depend on the relative demands for food and plastics. Monsanto is working on corn which produces a polyester as a by-product in the leaves.

World Fiber Trends

Lana Irish of Invista, the company formed from KoSa and Dupont's Textiles and Interiors business, provided data to illustrate how future fiber requirements would be met.

• 60 million tonnes of fibers, both natural and synthetic, were used in 2003.
• The growth trend over the last 25 years was a steady 3%/year, and if this continued as expected, 15-20 new fiber plants would need to be built each year for the foreseeable future.
• World population was 6 billion and had grown at a steady 1.07%/year for the last 50 years.
• Per capita consumption of fibers had grown at a steady 2.1% per year for the last 50 years to the current world average of 9.1 kgs/per person/per year.
• USA used most fiber, 36 kgs/pp/py while Africa /Mid East used least (3.1kgs/pp/py)
• Per capita consumption was growing in all regions, but most in the more populous less developed countries. ( China , India )
• By 2007, China would be the largest fiber user (14MM tonnes) followed by North America (13 MM tonnes) and Western Europe (9 MM tonnes)
• In 2003, polyester was the most used fiber with 38% of the market followed by cotton 37%, nylon 7%, polypropylene 6% and cellulosics 5%. However the 21 MM tonnes polyester was mainly filament (12 MM tonnes), so cotton was still over twice the volume of polyester staple.
• Polyester staple capacity has been comfortably ahead of demand and will be sufficient to meet an expected 13 MM tonne requirement in 2010, the increased capacity being in China .

world fiber consumption 1998-2007

For the future, Ms Irish saw sheath/core bicomponent fiber technology aiding the more efficient use of raw materials by using cores which would not alone form fibers inside more valuable fiber forming sheaths. There was no discussion on how oil shortages might affect the scenario.

Wipes Markets

Pricie Hanna VP of the John R Starr consultancy provided a taster for their latest market update. Wipes was the fastest growing major sector of the nonwovens industry and the major producers, BBA, Ahlstrom, Dupont and others have invested heavily to provide the necessary spunlaced substrates now that P&G had moved from air-laid for baby-wipes. Albaad, a leading Israeli producer was also starting up in the USA . Another leading spunlaced substrate producer, Suominen, had acquired a leading private-label wipes converter, Codi, in an attempt to earn more from the increasingly competitive supply chain.

• EU and NA sales of wipes at retail level was ~$8bn in 2003 with roll-goods value being >$1bn.
• Baby wipes, still the biggest sector, were bigger than Nielsen audits indicated. These would grow at 2-2.5% between 2003 and 2008.
• Higher growth (3-5%) would occur in the industrial and institutional sectors.
• Highest growths (6-7%) were possible in the personal care and household cleaning categories.
• Substrate usage was 7 bn m 2 , spunlace growing fastest as it replaced air-laid in babywipes. Spunlace now accounts for almost half the total wipes tonnage of EU and NA. By 2008 it would be the clear leader at almost double the air-laid consumption.
• Flushable intimate wipes are made with air or wet laid forming of pulp and short fibers and as demand increases truly dispersible wipes will be commercialised – to protect the sewage systems.

For the future, increased differentiation of nonwovens substrates using patterning (e.g. PGI's Apex technology) and printing would communicate special performance claims to the consumer.

Elastic bicomponent spunbonds

Jared Austin, a Research Fellow at BBA Nonwovens described the fabrics developed by Advanced Design Concepts, a JV between BBA and Dow. These comprised a thermoplastic elastomer sheath contained in and protected by the thinnest possible skin of a stretchable polymer with good fiber-forming properties. This skin, being just 10% of the total fiber, corrugates as the elastomer relaxes and give a novel “microtactility” to the spunbond fabric whilst doing little to hinder the elasticity of the core. The resulting silky texture is quite unexpected in a majority-elastomer product. In another iteration of the technology, Y-shaped elastomers are spun with polyolefin tips. These tips split off as the fabric is stretched (e.g. by ring-rolling) but tend to follow the elastomeric “core” giving an air-jet textured appearance and a micro-fiber feel.

The challenges to be tackled before commercial quantities of such materials can be made available at a reasonable price are:

• Spinning from big jets (>30000 holes) without defects.
• Transporting the easily distorted filaments in laminar air without them touching.
• Coping with the high surface friction and agglomerative nature of the corrugated filaments.
• Choosing the right polymers for different applications

Within the thermoplastic elastomers category there are styrenics (e.g. Kraton™ and Vector), PP copolymers, perhaps the most exciting group with Versify™ and Vistamaxx™, and the more difficult to use polyethylene copolymers, Affinity™, Engage™ and Exact™. The polyolefin elastomers can be produced for less than $1/lb whereas the styrenics would be ~$2/lb and the condensation elastomers (polyurethanes, polyesterethers and polyetheramides) would be substantially more.

Disposable applications would include laminates with elastic film for backsheets, diaper topsheets and attachments, and bandages. Stretchable SMS was also possible. A commercial elastic spunbond line will be starting in Jan 2005 and development of a spunlaced version, and more durable versions would commence later the same year.

Speciality Elastomers

Srivatsan Srinivas of ExxonMobil Chemical Co. said diapers needed overall elasticity for better fit, breathability for improved comfort, a soft hand, and above all an acceptable cost/performance balance. Conventional elastomers can provide the features but cost too much and are hard to process into spunbonds. The right final product cost requires the right polymer and easy compatibility with existing film and spunbond processes. Vistamaxx™ elastic and flexible semicrystalline polyolefins derive from a metallocene catalysed solution polymerisation process which gives a range of molecular weights, melting temperatures, crystallinities and elasticities, while bonding well to regular polyolefins. The ratio of propylene to ethylene comonomers provides the versatility, the Vistamaxx™ range being majority propylene, having densities of 0.86 to 0.89 gms/cc, Tg's between -20 and -30 0 C and melting points in the 40-160 0 C range. Clearly the ethylene comonomer disrupts crystallinity to depress the melting temperature.

Coextruded films of Vistamaxx™ with thin PP or PE skins show high elasticity and a better surface feel due to corrugation of the skin as the core retracts. Choice of draw ratio, skin polymer properties and the thickness of the skin allow tailoring.

Spunmelt fabrics have been made at TANDEC and Reifenhauser. Spunbonds show elongations of >200% with a tension set of ~10%, while meltblowns give elongations >100% with the same tension set. Bicomponent fibers with a Vistamaxx™ core are also under development.

4DG Spunbonds

Martin Moller of Ason Neumag reintroduced the 4DG “capilliary surface fiber” developed by P&G/Eastman, for which they now have the spunbond licence. The multilimbed 4DG cross section allows a 6 d/f fiber behave like a 37 d/f round fiber, and the grooves on its surface mean that when hydrophilically finished, fluid moves spontaneously and quickly along its length. The high surface area aids particle capture in filtration, and the high bulk in ADL's gives good 1 st and 2 nd acquisition times.

Spunbond 4DG Fiber

Asked when 4DG spunbonds would be available, Mr Moller said commercial production was due to start in the 3 rd quarter of next year. They could be hydrophobic or hydrophilic depending on additives and finishes. 1 denier versions were theoretically possible but had yet to be developed. Had they measured wet-back of 4DG ADL's? No, because they only had tows at present. Could the spunbonds be made on non-Ason equipment? Yes, technically, but Ason have the exclusive licence.

Flushability: why now and if now how?

Earle Sherrod (Consultant) provided some data on the US sewage systems. Of the 100 million installed toilets, 75% were connected to mains sewage, 24% connected to septic tanks and 1% indescribable. Surprisingly, 50% of septic tanks are within cities/suburbs, and 10-30% of all septic tanks are failing significantly at any one time. 67% of new toilet installations feed sewers and 33% feed septic tanks. Low flush toilets (1.5 US Gallons) were now mandated for new installations.

A quick test for flushability involved measuring the time a nonwoven takes to sink and then trying to lift it out on a glass rod. If it floats for more than 30 seconds it probably wont disappear in the first flush, and if you can lift it out on a rod its probably too strong to disintegrate properly in the pipework. More comprehensive is the National Sanitation Foundation's toilet test using a toilet, 60 ft of pipe with three 45 degree bends and a screen on the outlet. The product should disappear in one flush and nothing should be caught by the screen.

Mr Sherrod had invented a flushable product whilst with Kimberly Clark (USP 6783826), this being a laminate of coextruded films, one soluble, the other a very thin hold-out layer, and tissue. The tissue had initially been used just to aid wind up and conversion, but it stuck to the soluble film and proved useful in the final product. The film was waterproof from one side and delaminated becoming flushable when wetted from both. He thought the main problem with commercialising flushable products was the non-availability of a premium price to offset the more expensive production processes.

Flushability Update

Calvin Woodings (Consultant) observed that if the disposal of household waste could be designed afresh to cope with the nature of rubbish in the 21 st century, much more emphasis would be given to an efficient liquid waste disposal system. Such a system would take a significant load off solid waste collection and landfill by allowing biodegradables to be dispersed at the point of disposal and transported in water through streamlined piping to local sewage treatment which would anaerobically degrade it to recycle the energy content in the form of natural gas and pure water. Fertiliser would be a by-product. Savings from reduced kerbside collection and rubbish transportation would be offset in part by the need for higher domestic water consumption, but this could be recycled almost totally by modern sewage treatment.

The absence of infrastructure to make this possible meant that only products which were easily dispersible in the current toilets and pipework could be recycled in this way. The development of such products was proceeding at an increasing rate albeit targeting the lesser objective of increasing the convenience of hygienic disposables, especially wipes. From the most recent patenting of KC and P&G the following technologies were highlighted:

• Film/fiber laminates which are waterproof when wetted from one side yet dispersible when wetted from both.
• Ion-sensitive binders which lose wet-strength when the lotion is diluted in the toilet.
• Blends of polyethylene oxide (PEO) and polyolefins to make fibers, spunbonds and films with varying degrees of absorbency and solubility.
• Grafting polar groups onto PEO to improve its fiber and film forming properties.
• Grafting silanol group precursors onto PEO in a reactive extrusion process to improve the fiber and film forming properties, and to improve absorbency.
• Making bicomponent fibers with a starch core and thin polyolefin skin.

Air-Laid Synthetics

Jim Hanson (Marketing Technology Service) had done some quick and dirty experiments on his new Dan-Core air-lay pilot line to see how much synthetic fiber he could get through air-lay screens with different hole sizes. As expected, the bigger holes allowed more fiber through, but the web quality deteriorated because the synthetics could not be perfectly dispersed in air by the feeding and mixing equipment available. Furthermore it was possible that the synthetics involved, a 2denier Kosa bicomponent (25%) and a 15 denier Wellman polyester (75%) both at 6mm length were more likely to be finished for carding than for minimum cohesion. The biggest slots used, 6mm wide, allowed ~400kgs/hour throughput, compared with a maximum of 150 kgs/hr for pulp on the same head using the necessary 2 mm screens.

What deniers could the pilot line handle? 1 to 30. Could the line simultaneously lay a coverstock, ADL and SAP containing-core? Of course – see his next presentation.

Melt-blowing lyocell dopes

meltblown lyocell by Biax Fiberfilm

Ron Zhao the R&D Director of Biax Fiberfilm Corporation has developed a 15 inch wide melt-blowing head with 12 rows of holes giving 200 holes per inch compared with the 35 holes/inch of conventional heads. Each hole in the new head is a hollow needle surrounded by its own airflow, this arrangement allowing much higher productivity both per hole and per metre width. Experiments with lyocell dope showed that the sticky filaments fused together on the collector, this problem being diminished by spraying water into the forming zone, first at the laydown point, then into the cloud of filaments in the air before collection. The best results were obtained by spraying water into the extrusion zone, apparently through a second set of hollow needles alternating with the extrusion needles. BFC will now complete the construction of a 15inch pilot line to explore the process/property relationships in detail and optimise the spinneret design.

Melt-blowing Elastomers

Ron Zhao continued to indicate how the new spinneret could solve some of the problems associated with meltblowing elastomers. Elastic nonwovens could be made in several ways:

• By consolidation of heat stretched SMS fabrics (presumably polyolefin).
• By laminating a nonwovens to an elastomeric film or net.
• By coating a nonwoven with an elastomer.
• By spinning a bico spunbond with an elastomer core.
• Or by meltblowing an elastomer.

Elastomers were inherently sticky and compared to PP formed poor melt-blown with large numbers of stuck fibers. However the new concentric-air spinneret as used for lyocell, when set up with a wider nozzle spacing of 60-80 mils would make acceptable products. He had yet to measure the elastic properties, but guessed it would stretch more than 100%. Nozzle hole sizes were 20 mils.

Chitosan for odor control

Walter Becker, a Consultant from Krefeld ( Germany ) described chitosan, a deacetylated chitin, chitin being the main constituent of seafood shells and hence an abundant and underutilised renewable raw material. It was available in many varieties with differing molecular weights and degrees of residual acetylation for use in water treatment, papermaking, pharmaceuticals, food processing and cosmetics.

He presented results from an EU funded project (170 3001) designed to quantify the odor-reducing properties of 16 different chitosans using gas chromatography. Their liquid absorbing properties alone and in blends with pulp and SAP were also measured using the free swell and centrifuge retention capacity technique.

His model smell substances were ammonia and triethylamine (strong), dimethylsulphide and butyldisulphide (foul) and butylisovaleria (rancid cheese). These were introduced into a closed box containing 0 to 0.6gms of chitosan alone or in blends, and the headspace sampled for gas chromatography at intervals.

The selected odor absorbtion results showed:

• Odors were absorbed differently by different chitosans, i.e. the best for ammonia was not the best for butyldisulphide.
• Between 25 and 80% of the ammonia was absorbed depending on chitosan type (type not given)
• ~85% of butyldisulphide was absorbed by 0.5gms of 4 different types of chitosan at either 30 or 40 0 C.
• 0.1 gms of a swollen chitosan absorbed 90% of triethylamine.
• ~90% of the butylisovaleria was absorbed by 0.5 gms of 2 different types of chitosan.

Free swell and centrifuge retention results on the best chitosan were 14.6 and 0.7 (g/g) but another graph of SAP/Chitosan blends showed a free swell of 20 for 100% chitosan and 30 for 100% SAP. CR's were >1 and 10 respectively. A graph of absorption under unspecified load for an unspecified blend of fluff and SAP, with and without an unspecified level of chitosan showed that the chitosan gave a slight improvement.

Asked if the GC results correlated with panel testing, Mr Becker said his own nose agreed with the machine. Chitosans cost between $5 and $100/kg, and have proved non-irritating in cosmetic use.

New Polymer treatments for Wipes

Chris Barcomb of Vinamul Polymers introduced three new polymer systems intended to add functional properties to nonwoven wipes substrates.

Nacrylic ABX 30 is a harsh self-crosslinking high Tg polymer which migrates to the surface of airlaid substrates and adds “scrubbing power”. It can also be cured to create high abrasion and solvent resistance. Sprayed onto the non-wetting surface of an already bonded synthetic it forms beads which provide the abrasion. For air-laid, 40-60% add-on is suggested to get bonding and maximum scrubbing action. For moderate scrubbing, say on an automotive wipe, ~30% is adequate and for make-up removal or exfoliation, ~10% would work. It can of course be printed on in dots or lines to suit the marketing objective.

Dur-O-Set® Elite Plus is a cationically charged ethyl vinyl acetate which acts as a “dirt magnet” attracting anionic dirt and locking it to the surface. Because it gets dirty quickly it provides visual feedback of effectivness to the user. It can also provide improved pigment retention for applications needing anionic pigmentation. This could be used on airlaid, Nacrylic ABX-30 providing a scrubbing side and most of the strength, while the cationic at 4% on the reverse side improves the wet strength further. Ultra-strong canister wipes for tough domestic and industrial applications would result.

Structurecote polymers are naturally derived biodegradable bonding systems available in anionic or cationic form to give very high dry strength and stiffness to airlaid pulp while dispersing completely in water. These are foreseen as being useful for various oil and solvent wipes for polishing and cleaning. They can also be used in low concentrations to stabilise soft hydroentangled nonwovens to improve slitting and winding performance. This light bonding, the nonwovens analogue of sizes used to stabilise textile yarns, is removed by dissolution in the lotion to leave the usual soft wetwipe texture.

New Modified Pulp for Acquisition Layers

Richard Knowlson, Marketing Manager for Rayonier introduced XCell™ fiber, Rayonier's answer to the curly fibers (SSTC) developed by P&G/Weyerhaueser. Unlike SSTC, it was available in roll-form, does not have a curly shape, and details of the process were not given. (From the micrographs shown the XCel™ fiber looked tubular where SSTC was in the form of thin and twisted ribbons.) From the graphs shown:
• XCel™ had an absorbent capacity between CTMP and SSTC, but had the same centrifuge retention capacity as SSTC, about half that of CTMP.
• In diapers, 125 and 210 gsm XCel™ ADL's were compared with a standard 360gsm CTMP version. 3 rd insult acquisition times for both XCel™ products were significantly better, the 210gsm version said to match the cost of a CTMP layer. Rewet was also better for the 210gsm XCel™ layer. (1.1gms versus 1.15gms for CTMP!)

A Specific Area Rate Test (SART) has been developed to better understand Z-directional acquisition. This uses a disc cut from the diaper and tested in a cylinder to restrict X-Y spreading. On this test the 3 rd insult acquisition rate for the 210 gsm sheet was half that of CTMP, the cheaper 125gsm version being better also.

In femcare, the acquisition layers of a major brand ultrathin pad were replaced with a 15% lighter XCel™ layer. 1 st and 2 nd acquisition times were much improved and rewets were similar. The Xcel™ - containing pads showed reduced stain area.

Vis-Breaking additive for Melt-Spun

Paul Shields of Ciba Specialities Inc described Irgatec CR76, a peroxide-free, free-radical generator which can be added to the extruder to reduce the viscosity of a spunbond PP resin to that required for melt blowing. This allows the production of meltblown webs with finer, more flexible, stronger filaments and most importantly with a doubling in the hydrohead measure of barrier performance.

Properties of webs made from a normal 1800 mfi resin were compared to those from a 25 mfi resin blended in the extruder with different levels of the additive (0.9-2.1%). With 25mfi resin and 1.5% additive, hydrohead's of 800mm were obtained c.f. 450mm for the conventional resin. Air permeability dropped from 410 to 260 l/m 2 /s, tensile strength quadrupled and extensibility doubled. In calender bonding, the bonding window is broadened by the new approach.

The combination of spunbond polymer and additive offers cost-savings compared with the use of conventional melt-blown polymers. Waste reprocessing is improved. Furthermore, the system has no safety problems according to cytotoxicity, skin irritation and sensitisation testing.

The additive was also used in a 17 gsm Reicofil spun bond to increase PP MFI into regions where commercial polymers are not available. 0.5% of Irgatec CR76 with a 29 MFI PP raised the MFI as spun to 60 and increased the tenacity (24 to 34 gms) and the elongation (33 to 51%). In a second set of results comparing a 25 MFI resin with and without 0.5% Irgatec, the MFI increased to 45, the tenacity increased from 68 to 73 gms and the elongation from 55 to 62%. The bonding window was significantly widened. Mr Shields concluded that Irgatec offered both cost savings and product improvements to producers of melt-spun nonwovens.

In response to questions it costs about $8/lb and the amount needed for a 25-1200 MFI change would depend on extruder temperature and dwell time. The product only worked above 270 0 C. The free-radical decomposition mechanism targets the longer polymer chains preferentially and so is more precise than peroxide and gives a more uniform molecular weight distribution.

Speciality Wet-Wipe Formulations

Jim Robinson VP Sales and Marketing for Hygenitec catalogued the problems of the wet-wipe industry:

• The baby sector was mature
• Raw material prices were increasing
• Fibers were in short supply
• Government regulation of disposal and distribution
• Environmental concerns
• Low quality imports were growing
• Retailers continued to press for lower prices

But, in baby-wipes the brand leaders were doing well and the market for home-surface cleaners was showing high growth. (INDA estimates suggested total wipes would grow by 6.1% pa through 2008, with household being the best sector at 9.2%, and baby wipes the worst at -0.5% pa.)

He thought the best regulated applications for the immediate future would be, personal sanitizers, disinfectants, sun screens, insect repellents, and OTC topical treatments (anti-acne, anti haemorrhoidal etc). The best unregulated applications would be paint clean-ups, degreasers, animal care, car care, and outdoor wipes

For substrates , laminates would give enhanced performance from the properties of unlike surfaces. Special fibers and bonding systems would confer dispersibility, antimicrobial and biodegradable properties. Overprinting with various polymers would allow differentiation of appearance and aesthetics.

For lotions, microencapsulation would allow the microparticle delivery capability of a lotion to become more versatile. These microparticles are 20-100 micron diameter comprising a highly cross-linked non-swelling skin carrying 5 times its own weight of functional ingredients, for example:

• Benzoyl peroxide for acne care
• Silicones and sunscreens for skin protection
• D-Limonene for surface cleaning
• Perfluoropolyethers for surface modification

The effect of molecular weight on melt-blown properties

Andy Campbell, a Senior Engineer with Sunoco Polymers reported work done on the Nordson melt-blown pilot line with polymers of MFI from 800 to 1800 dg/min. The 29” line used 30 x 0.15” holes per inch, each passing 0.5g/min of polymer to make 20 gsm fabrics. Air-flow was varied in the range 50%-70% of maximum. The results were as follows:

• Fiber diameter, unaffected by the change from 800 to 1200 MFI, fell from 4.7 to 2.6 microns as viscosity dropped to 1800 MFI.
• Fiber orientation, generally slightly MD biased, moved subtly towards the isotropic with the high MFI.
• Fabric strength increased with MFI, (MD from 460 to 545 g/inch). The 1800 MFI resin proved less sensitive to air flow.
• Fabric elongation fell with increasing air-flow, increasing MFI appearing to decrease MD elongation and increase CD elongation.
• Air permeability dropped from 330 to 100 cfm on the change from 800 to 1800 MFI.

He expected worldwide melt-blown fabric production to increase from 300MMlbs in 2002 to 400 MMlbs in 2006.

Improving wipes surfaces

Steven Croft, Business Director for Oliver Products Co. described the advantages of using a gravure printing system for modifying the surface of wipes substrates:

• Different patterns of molten polymer could give perceived and real increases in functionality.
• Thickness could be increased controllably.
• Abrasive textures could be created.
• Different effects could be achieved on different sides.
• Anchorage of abrasive polymers was good giving durability and freedom from lint.
• Strength improvements are a useful side effect of gravure printing.
• The polymer can be used to deliver active materials over time.
• Hook and loop effects can be created.
• Non-slip surfaces can be created.
• Surfaces become heat-sealable.

Diapers from a high speed extrusion process

Mark Oliver of Microtac Systems provided the commentary to a slick video of Reifenhäuser equipment extruding a breathable 20 gsm PP film and then adding a 16 gsm PP spunbond which is fused to the film in a calender. Pins for manufacturing a mushroom tape clasping system are molded in grooves in the calender and the mushrooms themselves are created by melting the tops of the pins in a gas flame. The backsheet breathability is obtained by adding calcium carbonate to the film extruder, this being cheaper than buying a filled masterbatch. The film has a hydrostatic head of 2800mm at the current line speed of 350m/min. A later table gave the hydrostatic head as 87 mbar and the water vapour transmission rate as 3484 g/m 2 /day at 100 0 F. The production of 3-5 diaper layers side by side would be possible. After stretching to create breathability the edge strips are vacuumed off and a rotation-moulding-slicing machine carries out the final moulding.

In response to questions, the system had yet to be tried with elastic polymers, good mushrooms needed a 50 gsm film and there was no data on how the mushroom closures compared with other methods for peel force.

The Wingformer Air Laid System

Alessandro Celli, MD of A. Celli Nonwovens S.p.A related his experiences from testing the pilot Wingformer now installed at the Rieter Technical Centre in France .

• Very uniform 15-100 gsm sheets had been laid using 100% pulps.
• Throughput had reached 600 kg/hr/m on the 0.5m head, and this had been limited by hammermill capacity.
• The system worked well over the 30 to 80% humidity range so no humidification equipment would be needed.
• They envisaged integrating the Wingformer with spunbond to make SB/AL/SB composites for low cost absorbents and wipes.
• They use a moving screen which is continuously cleaned.
• Man-made fibers from 3-20mm will be tested next.
• One commercial unit is ready to ship and Mr Celli hopes to sell it soon.

Hygienic Disposables for the Obese

Ruth Zielinski of Childbirth and Womens Services PC said that if past trends could be extrapolated, 40% of the US population would be obese by 2008 and 100% by 2040. Within the obese category, “morbidly obese” (BMI>50) was growing fastest. Overabundance of food is the problem – 3800 calories/person/day now being shipped by the food industry within the USA – and remorseless advertising is needed to encourage its continued consumption. Diets don't work, exercise is only marginally helpful and baryatric surgery is one of the few successful treatments.

The obese are more prone to incontinence and constipation, and obese women more likely to have menstrual disorders. New designs of incontinence pads are needed because the biggest pads are now smaller than the clothes on offer for the obese. Here a low rise brief would be appropriate, and more comfortable, for people with a large overhanging stomach. Obese women experience more pad leakage during periods and find tampons hard to insert and uncomfortable. Bigger pads, especially longer pads appear to be needed.

Taggants in Fiber Form

Jeff Dugan, VP Research for Fiber Innovation Technology reminded us that FIT also have an exclusive licence for 4DG technology for staple fiber before reviewing the need for devices to help prevent currency, security papers and high value branded products from being counterfeited. FIT was now developing bicomponent fibers of the “islands in a sea” type where the number and pattern of 37 islands could provide up to 2 12 = 4096 bits of information when viewed through a microscope, presumably by a human being. If such filaments were cut to a 20 micron staple length, each marker would weigh 100ng and allow ~100 markers to be added to each gram of product without their concentration rising above 0.01% by weight. For food products the “Sea” would be an edible fiber like PLA, and the “islands” would be a soluble fiber like PVOH leaving a pattern of holes in the taggant. Finally FIT decided that the best and most easily readable approach would be to put more “holes” on the outside of the fiber than inside, giving a notched circumference which would be easier to read. Asked how the fiber would be cut to 20 microns, Mr Dugan said the only current way was to use microtomes so clearly the fibers would be expensive. However the weight needed would be very small.

The case against Laminates

Jim Hanson of MTS Kalamazoo argued that a variety of products currently made by the off-line lamination of different finished nonwovens could be made better and cheaper on a multi-head air-lay line like the one he had just installed in his pilot plant. The one commercial example mentioned was the Brillo Scrub'n'Toss, a laminate of a soft rayon side and a polyester high-loft scrubbing side with an abrasive hot-melt sputtered onto it. He felt this could be done on an airlaid line at 200m/min in one operation.

Recent Developments in Fuel Cells

John McCullogh, consultant to Hills Inc reminded us that fuel cells worked by reversed electrolysis, i.e. creating electricity and water by combing hydrogen and oxygen in a non-explosive fashion. They were relevant to our conference because they needed membranes and/or nonwovens and could replace batteries and their nonwovens separators. They were still expensive sources of energy compared with most others, but their use was growing and as energy prices rose they would come into their own. For instance some commercial trucks now used fuel cells instead of the battery/alternator combination because they allowed a silent and pollution-free means of keeping the electrical systems (e.g. air conditioning, refrigeration) running while the engine was off. Hybrid vehicles were the obvious extension of this where fuel cells replaced the batteries/alternators of current hybrid vehicles. The regenerative fuel cell, which could act as an electrolyser or fuel cell, storing hydrogen and oxygen whenever power was available for electrolysis, was currently the best energy storage device, yielding 600 watt hours/kg compared with ~50wh/k for a lead acid battery and 200wh/k for the best lithium polymer systems.

The key to widespread use of fuel cells was ready availability of low cost hydrogen. Nuclear powered electrolysis could do it and maybe China , now planning to install 60 new reactors over the next 5 years would be first. Less attractive were wind energy, photovoltaic electrolysis of water, clean coal (giving CO and H in the SynGas process) and methyl hydrate hydrogen sources (crystallised natural gas)

Microbiological Quality Management in Wet-Wipes

Wolfgang Siegert of Schülke and Mayr GmbH ( Germany ) repeated the presentation he gave at the EDANA conference in Barcelona earlier this year .

Asked if preservatives in the binder were helpful, Mr Siegert felt they would not work well enough to preserve the whole fabric. He felt silver would not be a good enough biocide for this application. Asked how long a pack would maintain its protection after opening he pointed out that the surface wipes would dry out, concentrating the biocide, so microbial growth would not be a problem but the elevated concentration of biocide on the topmost wipe might be.

The benefits of through air drying

Steve Hagen an Applications Engineer of Metso Paper reminded us of the virtues of through air drying in comparison with steam cans. In short, they are more efficient, take up less space, and result in a bulkier product which is better for filtration products, drapes and gowns, absorbent materials and wallpaper backing in the weight range from 10 to 300gsm.

Calvin Woodings


Thursday, 16 September 2004

Alternative Cellulose Conference – TITK Rudolstadt 1-3rd September 2004


 TITK 2004 Audience

Dr Bauer, MD of the Thüringische Institute of Textile Science (TITK) opened the conference observing that world lyocell capacity stood at 120,000 tonnes/year and the fibre was at a crucial point in its history. Would it remain a niche product produced only by Lenzing (who now own Tencel) or would it grow into a mainstream fibre? To grow it needed investment, but the barriers to entry were high and the markets for the fibre currently appeared saturated. TITK will continue to work on high value specialities using their version of the lyocell technology. He hopes to continue to increase volume and market penetration in speciality areas.

25 years of Tencel development

Pat White, Tencel Ltd's Technical Director reviewed 25 years spent taking the lyocell process from curiosity to reality. Charged in 1979 with developing a low cost, environmentally-friendly route to rayon which would allow the venerable viscose process to retire gracefully, he rapidly identified NMMO as the most promising solvent. Fibres made from NMMO were all but indistinguishable from the premium Japanese polynosic rayon in character, so the key developments were to devise a highly efficient recovery system for the expensive solvent, and to optimise the process to deliver acceptable throughputs despite the solvent's tendency to degrade cellulose explosively if pushed too hard. The success of the engineering development coupled with a strong fashion-led Japanese demand for fibre led to rapid expansion and Lenzing's entry into the technology. The result: excess capacity because the projected long-term increase in fashion-sales proved unsustainable. Fibrillation and its control has dominated process and market development from the start:
  • The inherent fibrillatability of the first fibres led to the nonwovens market being targeted while solutions to the fibrillation “problem” were developed.
  • Japanese success at harnessing fibrillation to develop peach-touch fabrics by enzymatic selection of fibril sizes led to the first major sales, and to the optimism for rapid plant expansion.
  • New techniques were developed (by Tencel Ltd and “pioneering” mills) to cope with the new fibre in dyeing and finishing.
  • Low fibrillation achieved by process optimisation increased process costs but did not make the fibre universally acceptable in textiles.
  • Low fibrillation using additional on-line cross-linking increased the range of textiles possible.
  • High fibrillation routes were developed to suit special papers and wet nonwoven processes.
Currently, lyocell sales of ~90,000 tonnes/year are equally split between nonwovens, standard fibre in textiles and cross-linked fibre in textiles, with disposable wipes being the biggest single market. For the future, Mr White foresaw:
  • The Lenzing takeover of Tencel will achieve the “critical mass” to allow further development of the technology and markets.
  • Variable-cost reductions by moves to lower cost pulps and improved operating efficiency.
  • Fixed-cost reductions by integration, maximising factory output, and higher sales.
  • Lower cost processing to garments in Asia allowing lower costs to the consumer.
  • Further rapid expansion of nonwovens markets.
  • New products in the pipeline will further reduce costs and expand markets.

    Pat White MBE

Filtration Products from Lyocell

Dr Kolbe of TITK presented results for tetrachloromethane (TCM) and toluene adsorption by lyocell fibres and nonwovens containing 100% active carbon on cellulose i.e. 50/50 mixtures of carbon and cellulose. The carbon from coconut shells had been ground to <25 micron diameter and the final fibre had an apparent diameter of 60 microns, with 10 micron particles clearly visible at the surface. The efficiency of adsorption for carbon in fibre over carbon alone was 60% with TCM and 55% with toluene. 50/50 zeolite/lyocell fibres had also been made, but here the efficiencies were much lower, <10%, presumably due to the effects of the alkaline dope on the zeolite structure. The carbon-containing nonwovens had been tested against specifications for cigarette filters and water filters but no results were given. One of the problems with this technology relates to the inability to use the best adsorbing carbons in the lyocell process, because these do not give adequate spinning stability, maybe due to particle size distribution after grinding.

Edible Food Casings from Lyocell

TITK have collaborated with Kalle GmbH on replacing the collagen sausage skins with an edible version based on their lyocell tubular film “wurst” casing. Dr Meister of TITK pointed out that most collagen now comes from intestines processed “abroad” and suggested that the risks of biological contamination could be high. Attempts to replace collagen with alginate or casein-based substitutes have both failed. The problem with lyocell film relates to its “chewability” or rather lack of it, and so TITK sought to improve this by adding globular proteins such as casein, gluten or soyabean protein. Whilst giving the desired improvement in chewability (i.e. reduction of wet strength) these unfortunately caused an unacceptable increase in wet extension. They deduced that powdery fillers which were insoluble in NMMO should correct this and the resulting “Nalobite”, a three-component film comprising 33% cellulose, 9% corn protein and 58% bran appears to provide an acceptable balance of wet and dry properties. The process now needs scaling up to allow extensive application trials. Asked if the product met FDA regulations, Dr Meister indicated that all materials were FDA approved. What about NMMO residues? These had been measured at about 15 ppb in the finished product. Could they do blown films? Not yet, but they have a project awaiting food industry requirements.

Innovative Dyeing and Finishing of Lyocell

Jim Taylor of Tencel Ltd examined the various commercial lyocell fabric processing methods that have evolved over the last decade, ranging from those required for fully-fibrillated highly casual jeanswear to those for classic formal garments:
  • Full garment wash : abrasion and fibrillation of garment seams occurs giving a very casual appearance and texture. Long treatment times and high abrasion meant sewing threads and garment trim choices are restricted to the more robust products.
  • Reduced garment wash . The fabric is degraded by magnesium chloride treatment prior to make up. Garment processing can then be more gentle and hence a wider range of trims can be used.
  • Softner-only garment wash : The fabric is protected by resin finishing before make-up so that a semi-formal “smart-casual” unfibrillated appearance and soft texture arises from the garment wash.
  • Fibrillated Mill Finish : a more formal look is created by fibrillation/defibrillation using enzymes in air-jet processing. Again the magnesium chloride pre-degradation can be used to shorten the process.
  • Non-Fibrillated Mill Finish : a classic look is obtained by avoiding fibrillation altogether, either in open-width cold pad batch or fully continuous jig or beam dyeing. Resin finishing is essential to prevent fibrillation in use, so soft-touch cannot be achieved. Alternatively the non-fibillating A100 Tencel or Lyocell LF (cross-linked during fibre production) can be used on conventional cotton finishing systems. A further possibility is to resin treat a fabric after the Fibrillated Mill Finish route.

  • Jim Taylor

Finishing Lyocell Fabrics with Enzymes

Alina Popescu of the Rumanian R&D Institute for Textiles and Leather has experimented with the enzymatic finishing of woven lyocell fabrics. The sequence of experiments used in air-jet processing were:
• Washing and/or causticisation to create primary fibrils.
• Enzymatic defibrillation
• Dyeing which creates secondary fibrils
• Bio-polishing with enzymes to create a more uniform distribution of secondary fibrils
• Tumbler processing
• Further enzymatic defibrillation
• Drying, which creates a few fibrils but the final fabric looks unfibrillated.

“Then Airflow” or “Thies LuftRoto” open-width jet machines gave the best results. Rope processing was possible but creased fabrics above 200gsm.

Conductive Lyocell for plastic reinforcement

Dr Niemz of TITK showed that loading lyocell with carbon and compounding the resulting fibres with plastic increased the plastic's conductivity significantly more than adding the same amount of carbon directly to the plastic. The effect was dependent on fibre length and fineness: the longer and finer the fibres the higher the conductivity for the same total carbon load. Clearly the fibres were overlapping in the final structure forming conductive pathways which would not exist in carbon particle dispersions. Lyocell loaded with 30-40% of carbon black has a resistance around 1 ohm/cm compared with 10 12 ohms/cm for pure lyocell. At this loading it's mechanical properties are similar to viscose. Scaling up the compounding process indicated that fibre breakage was a problem. TITK's pultrusion rig allowing the preparation of master batches of fibre reinforced plastic have allowed the inclusion of longer fibres and helped to overcome this problem.

Lyocell, viscose and polyester spin-finishes compared

Bernhard Goosens of BGB Stockhausen reported results from an experimental programme to measure the effects of 21 different spin-finish formulations on the frictional characteristics of continous filament yarn.
  • Sulphonated paraffins and ethoxylated fatty acid esters reduced dynamic fibre/metal friction on lyocell and viscose more than polyester.
  • For best dynamic fibre/fibre friction the three fibres require different finishes, the ethoxylated fatty acid esters and sulphonated paraffins again being best on lyocell.
  • For static fibre/fibre friction lyocell is also unique, but again the ethoxylated fatty acid esters appear best.
Mr Goosens was surprised that the smooth-surfaced lyocell fibre appeared so different to viscose or polyester. He felt there was something special about its surface which needs further investigation.

Silver-loaded SeaCell®

Christina Hipler of Friedrich-Schiller University, Jena has, with funding from Alceru-Schwarza, investigated the antibacterial and antifungal effects of the Alceru-Schwarza fibre “SeaCell Active”, a silver-containing version of the lyocell/alginate alloy fibre. The fibre proved effective against Candida albicans, C parapsilosis, C glabrata, C tropicalis, C krusei, Staph. aureus, and E coli in in-vitro testing. A 100 person patch test proved that it caused no allergic reactions or sensitization of skin. Ms Hipler suggested it could be used as a component of bed-sheets, shirts, socks, shoes, underwear, sportswear, protective clothing, hygiene products and home textiles. It would be especially useful for people with atopic dermatitis, transpiration problems, diabetes or obesity. The fibre contains 5,000-10,000 ppm of silver and should be usable in 5-20% blends with conventional fibres in textiles and nonwovens.

Bioactive Cellulosics

Nina Kotelnikova of the Russian Academy of Sciences reported the first reactions of modified microcrystalline cellulose (MMC) with biologically active substances such as N-dimethyl benzyl alkyl ammonium chloride (DMBAA), polyvinylpyrrolidone, and its derivatives Sovican and Catapol. She had also reduced MMC with silver nitrate and showed that metallic silver forms as nano-particles (35nm) in the cellulose. All the new compounds were shown to be antimicrobial.

Lyocell Fibre Structure

Dr Mohammad Rous of Lenzing , winner of this years “Most Promising Young Scientist” award, described the use of Raman spectroscopy on fibres dyed with fluorescent additives to elucidate further details of the fine-structure of lyocell. Calcoflour (fluorescent dye- MWt 960) could be seen to penetrate to the centre of never-dried fibres which collapsed irreversibly on first drying. (Never-dried modal and viscose fibres did not allow the dye to penetrate at all.) On dried fibres the dye penetrated part-way into the fibre, this depth of penetration increasing with alkalinity. Thus, after 24 hours immersion, the Calcofluor could be detected to a depth of 2.5 or 3.7 microns (neutral or caustic-dyed respectively). The observations fit the hypothesis that lyocell has a thin semi-permeable membrane on the outside of an accessible skin region covering a denser, less-accessible core.

Another Solvent for Cellulose

Dr Christopher Michels of TITK compared 5 routes to cellulosic solutions, 4 of these familiar (acetate, viscose, cupro, lyocell) and one unfamiliar: 1-butyl-3-methylimidazolium chloride or BMIMCl. BMIMCl melts at 60-70 0 C to give a yellow liquid stable up to 250 0 C with no measurable vapour pressure. It dissolves cellulose under conditions similar to NMMO with the difference that BMIMCl has to be totally non-aqueous. The solution reprecipitates in water to give fibrils comparable to those from NMMO or cellulose xanthate. Interestingly, the BMIMCl/cellulose dope (12% cellulose of 530 DP) has an endothermic melting peak 45 0 C below the melting point of the solvent and is thus stable at room temperature. Furthermore it only begins to oxidise the cellulose at 213 0 C, and is therefore dramatically more stable than an NMMO solution. Fibre properties from air-gap spinning into water show BMIMCl to be higher in tenacity and modulus but lower in extension than conventional lyocell fibre.

Dissolving Cellulose in Molten Salts

Dr Thomas Heinze of the Friedrich Schiller University, Jena classified cellulose solvents into derivatizing and non-derivatising, the latter being further subdivided into aqueous and non-aqueous. Comprehensive lists of each type were presented. Of particular novelty were the molten inorganic salt hydrates of the general formula LiX.nH 2 0 where X = iodide, nitrate, acetate or chlorate. Of these, the LiClO 4 .3H 2 0 salt in molten form would dissolve 1500 DP cellulose to form a clear yellow solution within minutes. NMR spectra could be obtained from these and cellulose II could be regenerated.
Dr Heinze was also interested in fully homogeneous processes for making cellulose derivatives by etherification or esterification. Acetylation to a Degree of Substitution (DS) of 2.4 could be achieved in 3 hours by adding an excess of acetic anhydride to a molten salt solution of cellulose at 130 0 C. In this case the molten salt was a mixture of sodium, potassium and lithium thiocyanates, but LiClO 4 .3H 2 0 also worked at 110 0 C. Carboxymethyl celluloses with a DS of 2.2 and unusual structure could be obtained from dimethylamine/lithium chloride solutions using monochoracetic acid and non-aqueous NaOH powder in a one step procedure. The same molten salt solution could also be used to prepare the silyl derivative of cellulose.
In a second paper on a similar theme, Dr Steffan Fischer of the Fraunhofer Institute, Potsdam discussed the use of the above mentioned molten salts in acetylation and carboxymethylation reactions. He reported that LiClO 4 .2H 2 0 while only swelling cellulose, did so sufficiently for it to convert from the I to the II form. LiClO 4 .4H 2 0, and LiClO 4 .5H 2 0 also swell cellulose but not as much as the dihydric form. He too found molten salt hydrates effective and efficient routes to cellulose solutions and derivatives of cellulose with high DS. Perhaps of most interest was the slide of apparently homogeneous blends of cellulose and polyacrylonitrile dissolved in, and reprecipitated from, a molten salt, showing a clear glass transition temperature.

Melt Spinning of Silyl Cellulose

Thomas Karstens of Rhodia Acetow AG reviewed their joint work with ITCF Denkendorf on the melt spinning of cellulosic fibres via the silyl derivative. Bis-(trimethyl)-silylcarbamate (BSC) penetrates cellulose easily and swells it sufficiently to allow silylation to occur salt-free and without catalyst. The resulting silyl cellulose could be melt-spun without additives at temperatures below 250 0 C and at speeds up to 1000 m/min. Hydrolysis of the silyl groups (1N HCl for 1 minute at 40 0 C) yields pure cellulose fibres and hexamethyldisiloxane, the latter being recyclable into BSC via the catalysed insertion of isocyanuric acid obtained from the thermal decomposition of urea. Lab. Scale operation has been demonstrated at high efficiency and the process is felt to have great potential for scale up. The fibres from the laboratory operation are 0.8dtex after de-silation, with a tenacity of 34 cN/tex and an extension of 4.5%. Wet properties are slightly better than the dry. Fibre Crystallinity = 55%.
The BSC is a costly analytical reagent so the team have synthesized it from the more readily available hexamethyldisilazane (HMDZ) and ammonium carbamate with a yield of 97%.

LIST dissolution of cellulose in NMMO

Two papers covered the progress made by LIST with their horizontal “Discotherm” dissolvers since Courtaulds rejected them as unsuitable for Tencel and chose “Filmtruders” in the early 1990's. Dr W Zhao of LIST Singapore mentioned 6 years of development with TITK resulting in the single-step dissolution process suitable for speciality products up to 1000 tpa. This appears to be the basis of the Alceru-Schwarza range of special fibres such as Sea Cell – see later. The first semi-commerical unit has now been ordered and will be installed in China for start up in mid 2005. Exactly where was not revealed, but the assumption is that it will be on a pilot line for the production of standard lyocell fibres.

Andreas Diener also of LIST AG pointed out that since their rejection by Courtaulds they had developed to achieve:
  • Highest quality fibre spinning
  • Safer use of NMMO
  • Flexibility of throughput
  • Ability to use cheaper pulps than a Filmtruder
  • Lower operational temperatures, (<100 0 C) these being safer, with less NMMO decomposition and higher recovery rates
  • Operation without stabilisers is possible (patent reasons?)
  • Water quenching in the rare event of an approaching exotherm
  • Better for blends with fillers, polymers, dyes etc.
Asked how big the new Discotherm system could be built, Mr Diener thought 10,000 tpa of cellulose thoughput would be possible, i.e. below Filmtruder capabilities.

Lyocell Fibre Spinning

The abstract promised a review of the methods used to increase the efficiency of fibre formation in commercial Tencel spinning. Malcolm Hayhurst of Tencel Ltd Spondon described a computer simulation of fluid flow in the air-gap illustrated with unit-free graphs to show how well the model had been validated against real measurements taken in spinning. The air-gap model was said to have been central to understanding the fundamental parameters which must be controlled to enable viable lyocell production. Tencel Ltd has also modelled the dope flow in the spinneret and the spin-bath flow around the filaments, but Mr Hayhurst could not expand on this.

Characterisation of Exotherms

Frank Wendler of TITK described the use of thermal analysis and UV/Visible spectroscopy to study the autocatalytic degradation of cellulose in NMMO solution. Extinction-time graphs at various temperatures and pressures, with and without stabilisers and other additives were measured using both a mini-autoclave and a Radex security calorimeter. Exotherm onset conditions could be established with some accuracy and these showed the importance of propyl gallate stabiliser in raising the onset temperature by 20 0 C. However two of the additives favoured by TITK to convert lyocell into speciality fibres, active carbon and ion exchange resins, both destabilised the solution and exothermed after 3-4 hours contact at temperatures around 130 0 C. This observation presumably led to the topic of the next paper – late injection of additives.

Lyocell with Additives

Mr Jürgen Melle of TITK compared static and dynamic mixers for mixing additives into lyocell dope just before extrusion. He chose the dynamic flow mixer “DLM HY HO” from Indag Maschinenbau as the most successful with the simplest design, easy maintenance and high reliability. This mixer was used to blend additives pre-dispersed in an 80/20 NMMO/water solution with the main dope stream to give 50/50 alloys of cellulose. Pigments and dyes could also be added to create spun-dyed fibres.
Superabsorbents , carbon and ion-exchange resins could now be safely incorporated by the new method, and clean-down time between runs was dramatically reduced. Injection of microspheres showed that the late injection process could be used to increase additive levels up to 160% on cellulose, at which point the fibre tenacity had only fallen to 17 cN/tex.

Confocal Raman Spectroscopy (CRS) on Cellulosics

Thomas Röder of Lenzing Pulp illustrated how CRS could allow the analysis of microscopic areas of fibres or their cross-sections to identify chemicals and elucidate the structure of the cellulose. CRS on sections through wood cells differentiated lignin and cellulose, and if the wood had been impregnated with melamine for composite use, the distribution of the melamine could be visualised and quantified. For instance while the lumen contained 100% melamine, the cellulose in the cell walls could be seen to have absorbed 11% melamine.
Illumination of the samples with polarised lasers, first parallel to and then across the fibre axis allowed crystal orientation to be determined with accuracy similar to wide angle x-ray techniques. The technique takes 6-7 minutes per fibre and Mr Röder suggested using three fibres and taking 10 measurements per fibre. Total chain orientation (as well as crystal orientation) would be a possible output when the data analysis techniques had been refined further.
Additive distribution could be visualised by the technique if the additives were good Raman scatterers. Quantification of additive levels at different points in the fibre was not yet possible.

Chromophores in Cellulosics

Thomas Rosenau of the University of Natural Resources and Applied Life Sciences at Vienna described a procedure to allow the identification of ppm-ppb traces of coloured matter in viscose or lyocell fibres. The fibres were extracted with a boron trifluoride-acetic acid complex, said to be more laborious but more effective than straightforward methanol extraction. Sodium sulphite was also needed to prevent oxidative phenolic coupling which would give spurious results. Cotton linters, being free of chromophores, were used as a control to check that the extraction method did not introduce any colours. Comparisons of lyocell pulp and fibre showed that the chromophores came from the process not the pulp, a fact which may not be true if cheaper pulps were used. The lyocell process created 6 primary chromophores, i.e. those arising from the degradation of cellulose, hemi, and lignin, and 5 secondary chromophores i.e. nitrogenous compounds arising from the solvent and its reactions with the primary chromophores. Structures for each were presented. The secondary chromophores have high extinction coefficients and can be seen as coloured even in nano-molar solutions. They are destroyed by peroxide or hypochlorite. Total chromophore concentration in lyocell was put at <10ppm.

Wednesday, 30 June 2004

EDANA's International Nonwovens Symposium: Barcelona: June 3rd - 4th 2004

Delegates from the nonwovens and related industries gathered in Barcelona to attend EDANA's 2004 International Symposium on 3rd - 4th June. They came from all over Europe, as well as from North America, Asia and the Middle and Near East to participate in the networking opportunities offered by an impressive 358 participants from 23 countries representing some 168 different companies. This figure represented a significant increase on last year's EDANA Symposium in Rome .

The Symposium offered an interesting mix of presentations covering Nonwovens Markets, Raw Materials, Process Developments and Wet Wipes. Amongst these were keynote papers from Paul Polman, President of Procter & Gamble Europe, on Business Ethics and Sustainability, and John Page, Director Fibres & Fibre Intermediates, CMAI, on the polypropylene and polyester supply chains.

Keynote 1: Business Ethics and Sustainability

Paul Polman, President P&G Western Europe, suggested that trust in business was at an all time low - only politicians were trusted less than businessmen - and good deeds went unreported in the media. Business is seen as part of the environmental problem and not part of its solution so there is a need to improve its image:
• Ethics is the key and this starts at the top of any business.
• Business must take responsibility for its economic, social and environmental impacts.
• Business must communicate its ethics to consumers, customers, and stakeholders.

The P&G communication process is being augmented by "Inside Out", an annual event where government, academics, suppliers, customers and the media are invited to a day at P&G to see what's happening and to discuss issues of common interest. This year it was held in the UK offices, next year it will be at Schwalbach. Other initiatives of note were:

• The Global Sustainability Report is the most downloaded document on the P&G website. provides detailed information about ingredients, their safety and how it is evaluated.
• ~75% of P&G's products are water-related so P&G is developing low cost ways to get clean water to the worlds poor.
• A new water purifier "PuR" is being developed to clean and disinfect dirty water at the point of use for less than 1 cent per liter.
• In the Philippines P&G is testing a product which halves the amount of water required to hand-wash clothes.

In concluding, Mr Polman said partnerships, with governments, NGO's, suppliers and consumers were the way to improving sustainability in global markets.

Asked about the sustainability of disposable diapers, Mr Polman ponted out that over the last 20 years, diaper packaging had been reduced by 70% and the energy use in diaper manufacture had been reduced by 30%. These trends will continue. Sustainability will be improved by innovation and many small steps in the right direction. He also suggested that a better mindset here would be to focus not just on making diapers, but on "child development". P&G and their "Pampers Institute" was doing this and had become the world's second largest website in the process.

One questioner observed that "all" consumers wanted biodegradable diapers and wondered why P&G were not making any. Here Mr Polman suggested consideration of the total life-cycle of disposables v. reusables. On this basis disposables are no more "unfriendly" than reusables. Furthermore, with many landfills being incapable of biodegrading even the most biodegradable of materials, one could argue that making diapers degradable was a waste of effort. Nevertheless P&G does take disposablility issues very seriously and has a group developing improved biodegradable materials.

Keynote 2: Rags-to-Riches

John Page of CMAI (UK) reminded us that polypropylene, being based on what used to be the flared-off by-product of ethylene production, is the cheapest of all polymers at 1.2 cents per cubic inch. 35 million tonnes were produced in 2003, 16% of this being spun into fibre. Demand is expected to continue to grow at 5-6% p.a. through 2008, and part of this will be met from the huge increase in ethylene production now coming on line in the Middle East . Most this new capacity will use ethane feedstock rather than naphtha so the availability of propylene as a by-product will not increase proportionately. Furthermore propylene demand is exceeding ethylene demand, so PP prices can be expected to rise through 2006 at least.

If PP is a rags-to-riches story, polyester is riches-to-rags by comparison. In 2003 China added 4 million tonnes of polyester capacity - equivalent to the total production of Western Europe . By the end of next year they will be producing 21 million tonnes of the polymer - 10 times their 1995 capacity, and will single-handedly have driven any value out of the polyester market. Supply and demand issues will affect the pricing of the main consitutents of polyester, paraxylene and ethylene glycol, and a short-term tightness in their supply will prevent the PET price from falling as low as it otherwise would. The PET/PP price differential will nevertheless diminish to between $100 and $200/tonne premium for the technically-superior PET fibre.

Asked how a high oil price would affect PET prices, Mr Page said there was no short-term correlation between crude oil and polyester pricing. Both were more affected by supply/demand forces. At best there was a psychological link: it was easier to raise PET prices when high crude-oil cost could be used to rationalise the need for an increase. Clearly if oil stays high for any length of time, then the price of polyester precursors will have to increase.

Regulation of Wet Wipes

Joachim Vogt, a biochemist with the product safety and regulatory affairs department at P&G Service ( Germany ) provided an insight into the workings of EDANA's Wet-Wipes Task Force and in particular the effects of the EU Cosmetic Directive 76/768/EEC on two key classes of wipes, the baby/toddler wipes and the personal care wipes. The 7th amendment to this directive, published in March 2003, was coming into effect in September 2004 and would clarify the issues regarding animal testing.

The use of animal testing within the EU would be banned for finished products from 11 th Sept 2004 and from 11 th March 2009 for ingredients. However the 7th amendment also introduces a marketing ban, prohibiting the sale of products which have used animal testing anywhere. This will come into force progressively starting at the first of these dates and will be total by the second. In addition any Class 1 or 2 CMR's (carcinogenic, mutagenic or reprotoxic chemicals) will be banned and 26 common perfume ingredients will have to be declared on the pack if their concentration exceeds 10ppm in “leave on products” (wet-wipes) or 100ppm in rinse off products – deadline March 2005. Furthermore, for cosmetics whose shelf-life exceeds 30 months a new indication of “period after opening = X months” must appear on the pack.

Should nonwoven producers be concerned when the regulations only apply to the lotion part of the wipe? Yes. They will have to test for leaching of any chemicals from nonwoven into lotion over a period up to the declared Use By date. Dr Vogt called for co-operation between nonwoven producers and wet-wipe producers to understand the interactions between lotions and nonwovens.

Microbiological Quality Management for Wet Wipes

Wolfgang Siegert of Schülke and Mayr GmbH ( Germany ) pointed out that all wet-wipes needed some preservative to prevent spoiling on storage.

For baby and cosmetic wipes these preservatives would have to comply with the Cosmetic Regulations, and here products from their Euxyl® range can be used. Raw materials should be checked for microbes, and water, the main ingredient was often a problem:

• Water should contain no more than 100 colony forming units/ml.
• Ion exchangers are a source of microbial contamination
• Unpreserved water over 3 hours old must be assumed to be contaminated.

Random checks on nonwovens are essential. Manufacturers QC checks on contamination are rarely valid or good enough by the time the nonwovens are used.

For the lotion, the key questions relate to the stability of the concentrate, and the level of antimicrobial protection remaining when diluted to use-level. Once applied to the nonwoven, is it even? Does it protect the nonwoven adequately? Uniform spray application to the unfolded nonwoven is essential: chromatographic effects can cause separation of ingredients if the nonwoven is allowed to soak up the lotion from a reservoir, and dip application can result in the nonwoven taking up some chemicals more rapidly than others.

Technical wipes come under the Biocidal Products Regulations and here Parmetol(R) A28 has proved the most suitable preservative for most formulations.

Wet toilet tissue has proved to be the most risky for allergic skin reactions. Here an increase in pH caused by nonwovens can give problems with the recommended Euxyl® K702 which is based on phenoxyethanol, benzoic acid and dehydroacetic acid. (Only the free acids are preservatives and these are mainly undissociated only when pH is held below 5).

Spunlace in Wet Wipes

Michel Vincent-Dospital of Tharreau Industries ( France ) showed wet-wipes turnover growing by 282% in the five years to 2002, but expected no more than 8% growth in the next 5 years. In 2002 spunlace accounted for 81% of EU personal care and baby wipes nonwovens use, and 73% of Household wipes use. The main requirements for nonwovens in these markets are tensile strength and absorptive capacity (for conversion), flushability and biodegradation (for disposal), and a variety of combinations of softness, strength, thickness, abrasion and aesthetics depending on use.

Trends in Nonwovens

Sherry Sutton of PGI Nonwovens pointed out that there are now over 70 million North Americans over 50 years old and they have unprecedented buying power. These are the "baby boomers" and their children are now creating above average gains in the 15-24 age group - the “baby boom echo".

• Roll goods shipments will grow at 5% a year to reach $5billion by 2007
• Disposables will reach $3.2 billion, comprising hygiene $820m, Wipes $690m, medical $480m, Filtration $457m, and others.
• Within Hygiene, training pants is the fastest growing, highest margin group, incontinence having the best longer term potential.
• Within wipes, now a $2.2billion market in North America at retail level, baby wipes account for $882m, Personal care wipes $554m, and Household $715m. However it is the emerging markets that are showing double digit growth:
• General Bathing wipes
• Facial Cleansers
• Disinfectant wipes
• Glass cleaners, dusters and polishers
• Car cleaners
• Pet care wipes
• Sun care and self tanning wipes

Incontinence pad users want washable products with the comfort, breathability and quietness of cotton underwear. They want protection and insurance against accidents. They also want disposable washcloths with no-rinse, deodorizing cleansers and moisturisers.

For the future she saw growth possibilities arising from flushable wipe developments, flame retardant nonwovens for home furnishings and further nonwoven penetration of the technical textiles market.

Nonwovens in India

Ravishankar Gopal, Consultant ( India ) reviewed the progress of nonwovens market development in India .
• With a population of 1 billion of median age 24 years, there is no market for adult incontinence products
• However half the population is between 18 and 35 and is receptive to new ideas and products.
• The middle class (250million) has purchasing power only a little below that of developed countries and are potential customers for disposables.
• The current low penetration of disposables (0.001kg/capita) coupled with the high birth rate (24 million per year) means a huge opportunity for nonwovens exists.
• In 2002 disposable nonwovens sales amounted to 38,000 tonnes, 32,300 being hygiene products, mainly femcare, and growing at 15% per year.
• The second largest nonwoven market, medical, used 2280 tonnes and was also growing at 15% per year.
• Durable nonwoven sales of 60,000 tonnes were mainly needlepunched for automotive and home furnishing applications, and fibrefill (20,000 tonnes).

In conclusion, Mr Gopal reminded us that India has only been "open" to foreign investment for 10 years, and will grow like China from now on.

Filtration Opportunities in China

Lutz Bergmann of Filter Media Consulting listed the opportunities for filters now arising as a result of China 's industrial growth:
• China is the worlds leading steel producer with 1600 plants, some requiring a million square meters of pulse-jet baghouse filter area.
• China is the worlds largest cement producer with over 800 plants. These will eventually have to comply with the 10mg/m3 emission limit, the demand for fabric filters being huge as a result.
• China is the second largest electricity generator on Earth, 75% being from coal-fired boilers using mechanical dust separators, i.e. an enormous opportunity for baghouse systems, probably using glass fiber filters.
• The 600 Chinese cities with more than 0.5 million inhabitants will have to install waste incinerators with stringent emission controls using high performance filters and dust collectors.
• Road construction projects will dramatically increase the market for aramid filters for hot-mix asphalt production plants.
• China is building a million apartments a month. Most of these have heating and air-conditioning units which require filters.
• Growth in Chinese microelectronic and pharmaceutical production will require more clean rooms with more HEPA filters
• Blood filtration will be required in future for the million pints year of donations.
• Chinese automotive production - now 3 million/year, could grow to 10 million by 2010. Engine air, oil, fuel and passenger compartment air filters will be needed.

Engineering Polymers

Martin Brück of Ticona GmbH (A division of Celanese) defined engineering polymers as those which have to operate at 100-150 0 C, as distinct from standard polymers (<100 0 C) and high performance polymers (>150 0 C). Ticona has a new melt-blowable version of Fortron® polyphenylene suphide, an FR polymer made from dichlorobenzene and sodium sulphide which can operate in filtration at up to 200 0 C with excellent resistance to solvents and hydrolytic degradation. It is also suitable for use in contact with food, and complies with medical regulations. Their Celanex® polybutylene terephthalate polymer is less prone to post extrusion shrinkage than polyester and can be run on spunbond lines at higher throughput to give softer finer fabrics with better hydrolytic stability. It is available in a wide range of melting points and can even be used as a bonding fibre for conventional polyester. Their new Topas® cyclo-olefin polymers demonstrate excellent electret charge retention (80% remaining after 80 days at 90% RH), and good resistance to acids, alkalis, and polar solvents. They are stable at temperatures up to 140 0 C, and have broad regulatory approval for food and medical applications.

Improved melt blowing

Hans-Georg Geus of Reifenhauser introduced a new peroxide-free additive from Ciba Speciality Chemicals to allow melt blowing of spunbond grade polypropylene. The EB 43-76 additive - now being launched as Irgatec CR 76 - allows the production of meltblown webs with finer, more flexible, stronger filaments and most importantly with a doubling in the hydrohead measure of barrier performance.

Mr Jörg Leukel of Ciba Speciality Chemicals compared the properties of webs made from a normal 1800 mfi resin with those from a 25 mfi resin blended in the extruder with different levels of the additive (0.9-2.1%). With 25mfi resin and 1.5% additive, hydrohead's of 800mm were obtained c.f. 450mm for the conventional resin. Air permeability dropped from 410 to 260 l/m 2 /s, tensile strength quadrupled and extensibility doubled. In calender bonding, the bonding window is broadened by the new approach.

The combination of spunbond polymer and additive offers cost-savings compared with the use of conventional melt-blown polymers. Waste reprocessing is improved. Furthermore, the system has no safety problems according to cytotoxicity, skin irritation and sensitisation testing.

Improved fabric inspection

Piergiorgio Mora of Electronic Systems Spa proposed using a combination of a beta-gauge basis weight scanner and a multiple static camera optical inspection system to get much improved basis weight monitoring and control. Single or double beta-gauge scanners are slow (20 seconds per scan) and hence record weight variations along diagonal lines across the web leaving vast areas unmeasured. Optical scanners will give 20,000 images/second and allow full inspection for visible defects, but are not good for basis weight determination due to problems with irregular transmission and diffusion of light, dust build up, and lamp ageing. However when both systems are combined, the beta gauge can continuously calibrate the cameras, allowing them to give a full assessment of basis weight variation.

Systems using this principle to control the chute feeders of cards allow the variability of basis weight to be halved compared with beta gauge control on its own.

Nanocoatings for Nonwovens

Dr Georg Bolte, MD of Nanotec S.R.L ( Germany ) defined a nanocoat as arising when an aerosol of sub-micron solution particles containing less than 20% solids lands on a surface and the solvent evaporates.

Fine aerosols are produced by nozzles (nebulizers) driven by ultrasonic or piezoelectric forces. Several nebulizers have been arranged to treat films and textiles up to 2.7 metres wide at 110 m/min. When combined with corona discharge surface treatment, nanocoats created from water-based aerosols can be bonded onto the surface of polypropylene to modify its surface tension. Another application example involved treating polyester film to lower the surface resistance from >10 -15 ohms down to 10 -9 ohms. Printing effects can be created by applying the aerosol through rotary-screens.

Biodegradable spunbonds

Dr Dieter Blechschmidt of the STF Institute ( Germany ) has produced spunbond nonwovens from Eastman's Eastar Bio™ (PTAT), Cargill Dow's Natureworks™ (PLA) and Bayer's BAK™ aliphatic polyesteramide (PEA).

Over a basis weight range from 32 to 194 gsm and fibre counts from 0.7 to 4.5 dtex stable production was possible with PTAT and PEA but not with PLA. PTAT and PEA gave softer and more elastic nonwovens than PP. The PTAT work was scaled up at Reifenhauser in Troisdorf and this polymer appears to be commercially viable in spunbonding. The PEA polymer is no longer produced by Bayer.


Bob Hartog of TNO, Holland's Food and Nutrition Research Organisation reviewed antimicrobial additives and their evaluation. In addition to the well known slow-release or no-release varieties, TNO has added "release on command" using a "bio-switch with bio-nanotechnology" to ensure that the antimicrobial is only released by the target organism. The patented approach uses starch-based particles containing lysozyme, whose release "is controlled by changes in the structure of the matrix".