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

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 .

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.

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

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

21/10/2004