Thursday 11 November 1999

Insight 99 San Diego November 1999

Insight Conference Hotel - San Diego

Michael Domin, Kimberly-Clark: Emerging Infectious Diseases Threaten 21st Century Global Village
Infectious diseases are evolving to resist antibiotics at an ever-faster rate, and the days when a single antibiotic could kill a wide range of bacteria have gone. Cocktails of AB's are required and even these are becoming less effective. Vancomycin is now widely regarded as the last uniformly effective treatment for Staph. Aureus and the Centre for Disease Control is urging its use as a "drug of last resort" to delay the emergence of vancomycin resistant bacteria. With nosocomial infection being the third ranking killer in the USA after HIV and TB, the case for prevention (improved hygiene in hospitals) over cure (more antibiotic use) was now obvious.Nosocomial infections were transmitted from person to person by direct or indirect contact, and 60% of them were traceable to poor hand-washing procedures. Nonwoven wipes with or without antimicrobials, for use on hands and surfaces that come into contact with hands could therefore become a major contributor to hospital hygiene.
In response to questions:
The simplest antimicrobials i.e. chlorine and iodine were the best. The more complex the molecule, the easier it became for an organism to incorporate it into it's biology and develop resistance.
Standard dishwashing fluid had proved to be the best handwash detergent in hospitals.
Vancomycin is indeed the last antibiotic of the current series. Drug companies abandoned AB R&D as paybacks fell. Work has now restarted but a vancomycin replacement is unlikely to be on the market before vancomycin resistant organisms have evolved. Vancomycin use must therefore be restricted.
Disposable diapers used in hospitals are not regarded as hazardous waste, at least in California.

Blake Kuster, Absorbent Technologies Inc: Global Production Of Superabsorbents Recently announced expansions of SAP production will take world capacity to 1.35 million tonnes by 2001, this being equally split between North America, Europe and Asia. The expansion is being driven by both supply and demand factors: a cheap and readily available supply of acrylic acid, and growing demand from the disposables industry. Acrylic acid feedstock, propylene, is expected to remain in the 10-13 c/lb range until 2001, and of the 1200 million tonnes of acrylic acid produced in the USA, over 30% is now routinely converted into the glacial form from which SAP's are made. SAP makers are therefore experiencing attractive raw material pricing and are encouraged to sell aggressively.
Stockhausen is the market leader with 22% of capacity, followed by Nippon Shokubai (18%), Chemdal (12%), BASF (12%), Dow Chemical (11%), Sanyo Chemical (7%) and Sumitomo Seika (7%). 81% of SAP's are used in diapers and training pants, 13% in adult incontinence and 2% in femcare. The US and Japanese markets are felt to be saturated, but Europe and the rest of the world - especially Asia - have growth potential. Within the market sectors, adult incontinence has the greatest growth potential. Diapers are already more absorbent than necessary, so it is clear that factors other than performance, i.e. the aesthetic and storage advantages of ultra-thin products, will drive the predicted SAP content up from 50 to 60%
Other trends of interest:
The development of less absorbent but more permeable SAP's (higher cross-linking).
The development of products specially for air-laid cores, the rapid (25% per year)
Growth of the new bladder control pads.
The emergence of diaper backsheet fracture problems arising from the high SAP loadings.
In response to questions:He put the world market for superabsorbent fibres at 2000 tonnes/year currently but felt these were selling largely into packaging end-uses. They would gain a foothold in disposables and would grow from there.
SAP-loaded air-laid's would be used to "cut and place" absorbency strategically in diapers. This would not translate into more SAP usage.
New polymers can be expected. (After all acrylic acid products are not biodegradable and consumerism can be expected to lead to a tax on waste.)
CMC based superabsorbents are far too expensive to challenge acrylics.
SAP still has to prove itself to US meat packers before food contact uses will grow. However Japan and Australia have already accepted it in food packaging.

Henning Skov-Jensen, M&J Fibertech: The Prospects For An Air-Lay Super-Site
He defined a super-site as a single plant air-laying 100,000 tonnes per year and festooning the output to feed on-site diaper production. The plant would have an on-line calender to densify the output to 0.4 gms/cc and bond it. It could even be built at a pulp-mill to achieve further integration.
The paper, like the earlier version given at Inda-Tec in September, was notable for it's comprehensive breakdown of the manufacturing costs of the super-site revealing the M&J machine would cost $58M. 6000 tonnes of short-cut bico. reinforcing fibre would be needed at an assumed price of $2/kg. The pulp would cost 55c/kg and the superabsorbent (45,000 tonnes/year) would cost $2/kg.

John Starr and Pricie Hanna (Consultants): Value Chain Analysis
The principles of "Value Chain" and Michael Porter's "5 Forces" analytical methods were applied to the disposables industry. The conclusions from such analyses were driving pulp companies to move downstream to capture more of the value in a disposable diaper by supplying air-laid pulps ready-mixed with SAP's. This would save the converter the trouble of having to defibrate and lay pulp/SAP on every diaper machine and would allow cheaper, more consistent products to be manufactured. The pulp supplier would extract greater value from the chain.
Large-scale investment was already taking place to provide air-laid pre-formed cores to the diaper and sanitary towel makers, and the pulp producers were in the vanguard. These cores would combine the functions of acquisition, distribution and retention in a multilayer stucture.
Other technology trends emerging from the analysis:Softer, loftier, microdenier topsheets, either spun laid or carded.
Stretchable covers and breathable fabric backsheets
Odour absorbing, pH neutralising SAP's

Andrew Urban (Consultant): The Troubled Private Label Diaper Industry in the USA.
Most retailers now sell branded diapers at a loss in order to attract mothers into their stores. Why do the retailers still want private label diapers on the shelves and how can the private label producers profitably make comparable diapers to sell at even lower prices? With the leading US private label producer - Paragon Trade Brands - now bankrupt thanks to P&G and Kimberly Clark patent infringement law-suits, answers to the latter question were not obvious. However retailers continue to want them because they are profitable, and because they help them to persuade the brand suppliers to keep prices down.
Market trends mentioned were as follows:
Private label diaper share fell from 20.1% in July 98 to 18.6% in July 99.
However annual shares for 98-99 were the same as for 97-98.
"Pampers"/"Huggies" share ratio fell from 28.4/31.3 to 26.3/34.6 over the last 13 week period.
"Luvs" share is essentially unchanged within the 15-15.5% range over the last year.
Private label costs will increase due to royalty payments.
Conclusion: The private label business is sick, but not dying. It will survive as long as retailers need it's diapers on the shelves.

Dick Moran (Consultant): Diaper Design Changes
The most important innovations in diaper design following P&G's kick-start of the industry with the original Z-fold one-piece diaper in 1970 were listed as:
J&J's introduction of tapes to replace pins
P&G's use of the hour-glass shape and elastic legs on "Luvs" in 1975
P&G's use of thin superabsorbent cores and compressed packs in 1985
P&G and K-C's simultaneous use of elasticated interior barrier cuffs in 1991
The introduction of Pull-Up's training pants by K-C
The extension of the pant design to baby diapers by Unicharm.

The need for perfect containment of urine and faeces has driven developments to date, but baby-care is now emerging as the new focus. Drypers use of aloe in lotion diapers did well in 1998 and this year P&G's "Rash Guard" is making inroads at the incredible price of 37.9 c/diaper (compared with private label Kroger "Ultra Comforts" by Paragon at 19.3 c/diaper.) "Rash Guard" claims are related to the use of a proprietary lotion on the coverstock, the use of a treated inner cuff, a breathable cover and a super-dry core.
In Japan Unicharm's "Moony Delicate Care" features an apertured hydroentangled top-sheet to achieve a more textile-like appearance.
Looking to the future, Dick (ex P&G) saw the following as "winners":
P&G's "Uni-Futur" diaper now on sale in SE Asia using a 4" wide elastic waist with "ears" and a thin rectangular core looking just like a pre-formed core ought to look. (This was a low-cost product being made available in just 3 sizes to cover the normal 5-size range.)
Unicharm's "Moony Man" pull-up diaper with ingenious elastication of the crotch to form the leg-bands.
Kimberly-Clark's expansion of the training pant range with an overnighter suitable for 85lb+ "infants".
And of course, the P&G "Rash Guard" principle.

Chris Barcomb, National Starch & Chemical Co: The Industrial Hygiene Of Chemically Bonded Nonwovens Unlike natural rubbers and latexes, the new synthetic emulsions do not contain proteins that could cause skin irritation and allergic reactions. Emulsion polymers have a long history of safe use in FDA regulated areas. Furthermore the latest Dur-o-set® Elite series of ethyl vinyl acetate binders contains only a tenth of the vinyl acetate monomer and formaldehyde residues found in conventional EVA's.
The latest self-crosslinking binders can give nonwovens yielding only 15ppm formaldehyde, sufficiently close to the "background" level of 3-5 ppm found on cellulose to be of no health or toxicological concern. Nevertheless, research striving for zero formaldehyde binders continues.
Edward Powers, Celanese Acetate: Low Temperature Calendar Bonding With Cellulose Acetate
Cellulose diacetate melts with some decomposition at 235oC and is generally regarded as a difficult prospect in thermal bonding. However if the moisture content is raised, the water acts as a fugitive plasticiser under pressure and webs can be calendered at around 170oC to give respectable nonwoven strength. 100% acetate, 80/20 rayon/acetate and 60/40 rayon/acetate blends were studied at a range of moisture contents, bonding temperatures and pressures using both plain and patterned calenders.
The best moisture content appears to be around 100%, but even 20% makes a difference. In patterned-roll calendering, 60% water, 157oC bonding temperature at 400 pli roll pressure gave good results. At 175oC the strengths declined due to the film-like nature of the bond points.

Dr Klaus Kohlhammer, Wacker Polymer Systems: Dry Emulsion Binders for Air-Laid Nonwovens.
Spray-bonding of air-laid pulp nonwovens or waddings gives good surface strength and integrity but fails to penetrate the thicker products and results in easily delaminated fabrics. The new Vinnex® emulsion copolymers in dry powder form can be air-laid along with the pulp and disperse uniformly through the thickness.of the web. When webs containing them are steamed or moisturised with 10 to 30% water, the binder becomes sticky and soft, adhering well to any surrounding polar fibres. Curing at temperatures above 150oC crosslinks the polymer and renders the final nonwoven heat and water resistant.
The current binders are especially suitable for thick waddings based on natural fibres and find application in powder bonded fibre sheets used in automotive industry.

Calvin Woodings (Consultant): Advanced Cellulosic Nonwovens.
The nonwoven industry was founded on the ready availability of low-cost viscose rayon fibres, and this fibre continued as the leading raw material until the mid-seventies. Since then the reducing cost of synthetics coupled with their easy conversion into binder-free spun-laid and melt-blown fabrics caused a steady decline in rayon's market share. Ways of redressing the cost disadvantage of man-made cellulosics over the coming decades involved operating the new solvent spun cellulose process (lyocell) on scales comparable to modern polyester fibre plants and changing it's feedstock from costly dissolving pulps to something more like bleached Kraft.
The market justification for a major investment in man-made cellulosics arose from the predicted inability of cotton to expand acreage or yield in line with predicted demand over the next half century. One study predicted the need for an additional 70 million tonnes of fibre by 2050 (a 150% increase) and while most of this would still originate from fossil fuels, natural cellulose was seen as the most economical and environmentally secure future source of "comfort fibres".
Past and future developments in spun-laid and "melt-blown" cellulosics were illustrated by reference to the patent literature. Recent work by Weyerhauser had demonstrated that on a small scale at least, excellent lyocell fibres could be spun from an NMMO solution of a treated Kraft pulp. Furthermore, direct extrusion of such solutions onto a conveyor belt could be set-up to give spun-laid cellulosic nonwovens, "melt-blown" microfibres nonwovens or a crimped tow free from the damage inherent in mechanical crimping processes. Centrifugal spinning was also described.

Kaj Back, Ahlstrom Lystil: A 3-Layer Soft Wet-Wipe.
This Finnish wet-laid nonwoven producer has developed a way of making a bulky three-layer wipe to compete with the thin, but cheap, creped paper now used in most single-pack wet wipes. The process uses one headbox and achieves true integration of the layers - typically a thick pulp/bico core with thin rayon/bico skin - to give a soft surface. Other combinations are of course possible, but competing in the single pack wet-wipe market requires low cost materials. Single-packs are used for refreshing wipes, spectacle cleaners, computer wipes, shoe cleaners and cosmetic samplers. The packaging machines for these are incapable of using hydroentangled fabrics, but cope well with the Trinitex® product which offers improved liquid retention, bulk and softness over creped paper.
Although more expensive than creped paper, is Trinitex® is a minor component of the total cost of single-packs and the extra cost is easily recouped from savings in lotion consumption. Furthermore, the extra thickness and absorbency means that significantly less fabric is needed per pack.

Rosario Maggio, ICBT Perfojet: The New "Spunjet" Spunbond Process.
ICBT Perfojet has seen an opportunity to supply PP spunbond lines based on designing out the known deficiencies of existing lines and building to a higher quality standard. They claim:
Improved aerodynamics in the quench zone
Better quench-air temperature and flow control (0.2oC and 0.02 m/s accuracy)
Modular concept (identical 500mm spinning modules across the machine width)
Better polymer distribution and melt temperature uniformity (+/- 0.5oC) to the spinning beam arising from multiple distribution plates
Crosswise draw force variations reduced to +/- 2-3%
Improved control system with friendly man-machine interface
Easy maintenance arising from modularity, quick disconnect techniques, and easy access
Integrated ducting, cabling and piping included in cost.

The new machine is said to run faster, and make finer fabrics with less waste and downtime than the competition. Filament speeds of 2500 to 3000 metres/minute were claimed and while the current pilot line works at 120 kg.hour/metre, it is being modified to achieve 220 kh/m at 1.4 denier per fil.

Jim Hanson, MTS: A Review of Airlaid Competition.
His 1998 review had predicted 3 new big air-laid installations for '99, and two have materialised: McAirlaid's 30,000 tonner and Buckeye's 50,000 tonner. The viability of airlaying for pre-forming femcare cores is now assured and its commercial use in diapers is imminent.
Key pointers to future developments were:
12mm man-made fibres were now handleable at commercial rates.
Only 5% bonding fibre is required (used to be 13%).
Thermal bonding fibres and methods are changing to alleviate the dusting problem.
Further increases in SAP loadings (up to 80%) can be expected.
The best pulps come from the dissolving mills. Mercerised pulp is especially good.
600 m/min at 5 metres width is now widely regarded as feasible.
The 100,000 tonne machine WILL be built.
Airlaying will outperform carding as a way of feeding uniform webs at high speed into hydroentanglement.
Smaller production units will make sense to supply the smaller diaper makers.
Air-laying will be used to make 100% man-made fibre acquisition layers.
Air layers would be used in cities to process waste paper (excluding newsprint).
Cotton linters were excellent in air-lay for wet-wipes. The process could be used to put a cotton veneer on a pulp core.
Another "super-site" announcement is expected in the spring.

Bruce Kirk, BT Associates: Sanitary Tissue Market Developments.
Worldwide usage of sanitary tissue is about 19.4 million tonnes per year, or about 6% of total paper and board usage. North America accounts for 35% of this, but is a mature market with less than 1.9% annual growth since 1990. By contrast, the Asian market (27% of the total) is growing at 6.8% p.a. and even Europe (26% of the total) is growing at 4.7% p.a. Capacity will expand by 5.9% in 1999 with the construction of 8 new large scale units, 4 by P&G, 2 by K-C and one each by Fort James and Georgia Pacific. World rankings have changed dramatically since 1995 due to frenetic merger and acquisition activity. K-C the current world leader and number two US producer was fifth in the US before acquiring Scott Paper. Fort James the current US leader was formed from the previous second and third place producers, Fort Howard and James River. No's 3 and 4 in the world, P&G and SCA have also grown by acquisition and the process will continue. While a long list of acquisition targets remains, the current leaders are expected to stay leaders. P&G are expected to "prove that brands will travel" by introducing "Charmin" and "Bounty" to Europe and Asia.

Dieter Muller, Bremen University: Odour Reduction In Adult Incontinence Products.
He reviewed how the sense of smell worked, highlighting the molecular forms giving rise to pleasant and unpleasant odours. The concept of "threshold concentration" was important because odour molecules did not have to be eliminated if they could be absorbed (or diluted) to concentrations below the detectable threshold. Temperature, humidity, training, cultural background and environmental factors all affected an individuals appreciation of odours. Some natural and synthetic macromolecules had porous structures that could absorb and retain odours, and in solution, these could be sprayed onto the acquisition layer of adult incontinence products. Gas chromatography had been used to check the concentration of urine odours (ammonia, ketones, dimethylsulphone etc) before and after absorption onto a nonwoven sprayed with cyclodextrin solution. 30 to 50% reductions were obtained, with higher absorbtion being possible at longer contact times.
In response to a question, he had no data on the effectiveness of baking soda as an odour reducer.

Sten Bjornberg, KBS Development: Natural V. Synthetic Blood For Testing Sanitary Napkins
Five test fluids made from human and animal bloods were compared with 4 synthetic fluids for viscosity and surface tension, for absorbtion speed and rewet (on "Always" and "Libresse" pads).
The conclusions:
Real blood is much more viscous than the synthetics at low shear rates.
Sheeps blood viscosity drops dramatically on cooling.
Synthetic body fluids absorb faster than blood, while synthetic menses absorbs more slowly.
Stockhausen fluid doesn't absorb after the first insult, but human blood continues to absorb through the second and third insults.
Pad absorbtion is increased by movement.
Rewet levels are generally higher with real blood.
Overall, real blood is the best test fluid with defibrillated sheeps blood coming a close second. (The human blood biohazard issue can be neatly avoided by always testing with your own blood!)
In response to questions:
McAirlaid cores give faster absorbtion than Walkisoft cores,
P&G's "Dri-weave" is a very superior topsheet compared with spunbond.
Milk is a better test fluid than synthetic urine but is really not good enough.

Ian Cheyne, Camelot Technologies: Unconventional Absorbent Fabrics.

The combination of high-loft and air laying techniques was shown to be capable of giving pads with good absorbency and better aesthetics than air-laid alone. Two approaches were examined. The first involved air-laying a mixture of superabsorbent fibres (30%) and pulp onto a pre-formed, through-air bonded, high-loft acquisition layer. This gave superior acquisition times and runoffs, but the resulting pad was too stiff due largely to its increased thickness. The second involved needling a carded web into a pre-formed air-laid comprising AD and absorbtion layers also using superabsorbent fibres. The resulting 3-layer web gave great aesthetics and much improved acquisition rate, rewet, and run-off. Patents targeting applications in diapers, training pants and adult incontinence have been filed.

Edward Mclean, Cotton Incorporated: The Use Of Cotton In Air-Laid Nonwovens.

Cotton linters and blends with woodpulps had been compared to woodpulps in hammermilling, air-laying and absorbency testing with the help of MTS and Buckeye Cellulose Absorbent Products Group:
Cotton requires less energy to defibrate but gives more nits.
Cotton tends to block the screens needed for pulp, but runs OK slowly without the screens.
Cotton is more absorbent than pulp (18.5 g/gm v. 17 gms/gm) but does not distribute fluid as well at normal core densities.
It gives similar retention under pressure.
It can be regarded as broadly equivalent to pulp technically.
Consumers would always express a preference for the cotton containing cores.
Cotton Incorporated spends 8% of turnover on marketing and will licence anyone who incorporates more than 60% of cotton in an absorbent core to use their new trademark Absorblend™. (SAP content is excluded from the blend ratio calculation)
They could not give a figure for the tonnage of linters currently available in America, but indicated that second-cut linters, i.e. the very short hairs normally left on the seed after linter removal, could be more available in future.
Other new developments mentioned were:
Wet-laid 60/40 linter/pulp nonwovens give dramatically better wipes.
An announcement of new cotton-containing baby wipes can be expected within 6 months.
Cotton/synthetic topsheets are being used over a cotton core to make diapers for newborns. (launched at recent Neo-Natal World Show)

Ram Shet (Consultant): Extractables in Hygiene Products.

Extractables were defined as the material leached out of SAP during 16 hours of contact with 0.9% saline solution. They comprised mainly low-molecular weight sodium polycrylate and could range from 5% of a high cross-linked SAP to 20% of a low cross-linked SAP. "Potential Extractables" arose from other materials used to make the pads, i.e. debonders, finishes, surfactants, adhesives etc.
In addition to their possible affect on delicate skin, extractables reduce absorbency under load and swelling rate and contribute to gel-blocking.
They arise from:
Monomer depletion during polymerisation.
Non-uniform or low density cross-linking.
High "hold temperature" and dwell time after reaction. (Required to reduce acrylic acid monomer residues below 1000ppm)
High drying temperatures (again required to minimise monomer residues).
Whether or not they diffuse from the wet gel depends on their molecular weight relative to the molecular weight between cross-links in the main gel network. However surface cross-linking technology had been a huge breakthrough, enabling more extractables to be retained than would otherwise be possible.

James Westphal, Troika Nonwovens Inc. And Danweb: Air-Laid Nonwoven Technology.

This year's new capacity start-ups and announcements were summarised as follows:
Air Formed Composites 6000 tpa multibond Danweb line in the USA
McAirlaid's 40,000 tpa densified core Danweb line in Germany
Concert's 17,500 tpa multibond Kroyer/M&J line in Germany (2000)
Main Spa's 10,000 tpa multibond Danweb line in Italy (2000)
BBA's ???tpa Kroyer/M&J line in China (2001)
His talk also featured :
Buckeye's "Streamliner" ad for the Vizorb® pantyliner core using cotton linters.
Buckeye's "Cottonaire" pantyliners where cotton usage obviates the need for coverstock.
Single-lane festooning by KorTec GmbH allowing converters to run for an hour on a single package. (and also 7 to 10 tonnes of airlaid core per containerload)
Multi-lane festooning from Gevas GmbH, packing 70mm wide 150 gsm webs at 0.1 g/cc and 1200mm roll diameter. (The final pack contains 10 rolls per block, or 102 kgs all spliced together for continuous running.)
Rayonier's continued interest in scaling up the Novathin™ air-laid core.
Future targets for the machine suppliers:
Lower costs per tonne output
Better control systems
Higher first quality yields (up from the current 80%)
Breaking the 500m/min barrier
Selling several 40,000 tonne machines to inco-pad producers
75% of lines on multibonding by 2003
Adopting festooning as the packaging of choice
Adding densification to production lines
Foaming colour onto products destined for the European tablewear market.

Larry Wilson, Dow Chemical: Determining The Core-Shell Structure Of SAP Particles By STXM.

The core-shell SAP's give the best performance but the shell can rupture after abrasion in diaper manufacture. This rupture allows the lower cross-linked internal polymer with its higher levels of extractables to leak out on wetting, and spoils the absorbency under load performance.
To allow the core shell structure to be clearly seen in the wet state, Dow has used high- energy synchrotron X-rays as the illumination in scanning transmission microscopy.
A thin section of granule, moistened and sealed in silicon nitride capsules are viewed. 2 to 10 micron skins, sharply defined or of graduated density depending on the manufacturing process, are clearly visible.
Ball milling was used as a severe simulation of abrasion in conversion, and a relationship between shell morphology and attrition sensitivity was found.
Dr Lindsay Kerr, National Association for Continence: Consumer Focus 99 Survey Results.
NAFC has 127,500 members, 98000 of whom were mailed the 1999 survey questionnaire. 2000 completed forms were returned by the deadline.
Analysis of results suggests: The average incontinent person is 67.2 years old.
Their average household income is $44,360.
61.3% are on Medicare, 25% enrolled in HMO's, 5.7% are covered by Medicaid and 2.4% had no health insurance at all.
19.2% of men and 8.2% of women reported no control of their bladders.
Consumer dissatisfaction with treatment measures has risen from 34.6% in '93 to 62.1% in '96 and 63.9% in '99.
5.3% of respondents had never sought professional help compared with 11% in 96 and 13.5% in '99.
About 50% of both men and women rated non-surgical, non-invasive, non-drug treatments as most helpful.
Only 3.3% felt cured by their treatment.
Only 8.6% were "very pleased" with the outcome of treatment.
With regard to disposables use, tissues were the most common absorbent for light problems, pads were used by those moderately incontinent, and the heavily incontinent used durables or catheters.
The figures were said to indicate the presence of very many unfilled needs in the marketing sense of the phrase, and very many innovation opportunities for technologists.
US incontinence care costs were put at $16.4 billion.

Ruth Zielinski, Childbirth And Womens Services: The Causes And Prevention Of Diaper Rash.

Common diaper rash arises when overhydrated skin is irritated by friction and the ammonia/high pH arising from faecal-enzyme breakdown of urine. Secondary problems can arise due to infections (candida) and allergic reactions to diaper components.
Prevention measures:
Keeping the skin dry and healthy by changing diapers as soon as they were wet (20 times a day for a new born and 6-7 times a day for a 1 year old.)
Modern superabsorbent diapers are much better than the old ones except when mothers decide to leave them on for longer.
Mild cleansing is recommended at every diaper change, but wet-wipes containing fragrances or chemicals should be avoided.
Barrier creams were helpful but only if applied sparingly. Too much could block the coverstock and hold urine against the skin.
Lotion diapers with cream applied to the coverstock in a controlled fashion were looking promising.
Breast fed babies have a lower incidence of rash than formula fed babies.
The low risk approach is to stop using diapers.
Ventilated diapers would be better than breathable.
When does a diaper that guards against diaper rash become a medical device?

Cliff Marshall, Bandz Inc: Savings And Benefits From Thinner Air-Laid Cores.

The view that air-laid cores will increase diaper costs is based on raw material considerations only. Bandz have attempted to calculate the additional savings from the use of air laid:
$650,000 would be saved from reductions in packaging required for the thinner diapers.
$260,000 would be saved from doubling truck payloads.
$54,000 would be saved on energy use (no hammermilling).
$45,000 would be saved from reduced downtime.
$26,000 would be saved from a 20% reduction in maintenance costs.
Another $26,000 would be saved by avoiding the 2% SAP loss that accompanies conventional diaper making.
In addition pre-formed cores would remove the defibration bottleneck on some lines and lead to increased throughputs.
Compared with an additional $990,000 in annual raw material cost for each diaper line, an overall saving of at least $71,000 per annum is achievable by switching to pre-formed cores.

Ivo Edward Ruzek (Consultant): Baby Diapers: The Continuous Challenge

Recent diaper design improvements have been directed towards:
Allowing diapers to work for several urinations.
More perfect containment of urine within the core.
Dermatological skin treatments.
Considering the next generation Mr Ruzek expected the real topsheet, i.e. the hydrophilic portion between the hydrophobic leg cuffs and edge strips to get smaller. This would place great demands on the surfactants used to keep polypropylene coverstock wettable through several urinations, and would lead to the use of soft, bulky hydroentangled and apertured structures stabilised by through-air bonding. The need for permanent hydrophilicity could even let in carded hydrophilic fibres, polyester being given an example.
For the hydrophobic areas of topsheet, SMS appears ideal until the need for it to carry cosmetic lotions arises. With lotion SMS becomes transparent to varying degrees and looks awful. The solution is apparently to use transparent microdenier (around 1 dpf) spunbonds that conceal the lotion while being attractively soft and textile-like.
For the Cores, increased SAP levels to extend diaper use time and reduce thickness will demand superior acquisition and distribution layers to deal with the slower uptake of the low-woodpulp cores. These will need to be permanently hydrophilic and resilient. Bico polyesters with spiral crimp would be one solution and blends of polyesters with differing melt temperatures would be another. High SAP cores may also need a core-wrap to keep the powder in, and tissue would no longer be appropriate. Ultra-light spunbonds or SMS structures at around 10 gsm would be needed.
Backsheets would of course be porous microfibre SMS structures, leakage being controlled by fluorocarbons. They would be printed or embossed to simulate textiles.

Gary Gilkes, Datasorb: A Test-Rig And Software Package For Pad Absorbency Testing.

The Datasorb "Protester" simplifies testing, removes operator error and allows the standardisation of test parameters such as fluid flow rate, hydrostatic head pressure, and acquisition end-point. Adaptations allow it to measure absorbency under various loads and rewet.
The following papers were in a simultaneous session. The notes below are from the published summaries:
Gary Hawkins & Cathy Dorher, Eastman Chemical Co: New Polyethylene Resins For Hygienic Films
Eastman Chemical Company produces MXSTEN™ elastomers and HIFOR XTREME™LLDPE polymers for film in hygienic applications. Films fabricated from the new resins are characterized by excellent bi-directional tear strength, puncture resistance, tensile strength, elastic recovery and stiffness. Fortunately, the increased stiffness does not take away from the soft feel provided by polyethylene polymers. A better MD/TD balance of properties, when compared to conventional metallocene catalyzed polymers, is achieved, and the unique molecular architecture can promote enhanced breathability and elastic recovery.

Larry Wadsworth, Tandec: Enhanced Barrier Performance Of Bicomponent Fiber Meltblown Nonwovens
The preferred polymer for producing meltblown is polypropylene, although PE, PET, PBT, PCT and most other thermoplastics may be processed. Bicomponent fibers may also be successfully melt-blown. Although core/sheath (CS), side-by-side (S/S) and other configurations may be prepared, the S/S configuration is preferred because of the possibility that greater fiber crimp can be achieved due to density gradients on the different sides of the B/C fibers.

Kathleen Hachey & Alton Gasper, 3M Company: New Polymer Melt Additives
Two new polymer melt additive materials have been developed by 3M. Although the materials can be used with a variety of substrates, including films and fibers, their primary utilization will be in nonwovens. These products are not intended for hygiene applications but are suitable for use in sorbents and wipes for the hydrophilic polymer melt additive. The repellent melt additive is expected to have significant utility in protective garment applications. This paper presented data related to the applications mentioned above as well as information relative to melt additive functionality.

C R Woodings Nov 99

Thursday 30 September 1999

Inda -Tec 99: Atlanta - Sept 21st -23rd 1999

Jeff Dugan of Fibre Innovation Technology Inc. on Bicomponent Fibres

Conventional splittable fibres are made from (say) 8 segments of nylon and 8 segments of PET in a "pie-wedge" or "Citrus" configuration. The two different polymers have a low affinity for each other and therefore split easily into microfibres when stressed. They are used for synthetic suedes and leathers, wipes and filters. Problems with this long-established variety included difficult (2 step) dyeing needed for the textile end-uses, a tendency for nylon to fade easily, and to offer inferior chemical stability for some filters or indeed, some wipes.

To solve these problems, FIT were investigating fibre shape effects and different polymers. Round fibres with their mimimum surface/volume ratio had the least appropriate shape for splitting and this placed greater demands on using very different polymers in alternating segments.

  • Flat fibres made up of alternating polymers across the width were the easiest to split.
  • Y-shaped fibres with limb-tips made from different polymer from the core were easily cardable, harder to split, but much better than round fibre.
  • The segmented X-shape was a good compromise between flat and Y. (but in questions he admitted this was theory: the fibre had not been made.)
  • Tubular round fibres with a citrus configuration were more splittable than a solid round fibre.

With shape adjusted to reduce the demands on polymer incompatibility, one could contemplate the ideal all polyester or all polyolefin splittables.

  • For a start, the problems caused by nylon could be minimised simply by minimising the nylon fraction in a round citrus fibre. Nylon could be used to do no more than isolate the polyester segments from one another.
  • Using the renewable, crop-based Poly-lactic acid polyester (PLA) instead of nylon gave a surprisingly good all-polyester citrus fibre. The aliphatic PLA with its helical crystal structure has a very different surface energy to the aromatic, linear crystallised PET, and splits from it easily. Here the PLA gave other advantages related to its inherent absorbency, dyeability and comfort, all this without significant loss of strength, resilience or economy c.f. nylon.
  • Poly-methyl pentene (PMP) is a true polyolefin with chemical properties between PP and PE but melting at 240 oC. It splits from PP readily and makes a technically superior all-polyolefin citrus fibre. It's high cost (~$4/lb) is a problem which can be minimised by using it as no more than a coating on the PP segments.

A PP/poly acrylonitrile (PAN) splittable fibre looks both practicable and surprisingly advantageous:

  • BP's "Amlon" thermoplastic acrylic is cheaper than PMP and gives an excellent splittablity/chemical stability balance with PP.
  • PP and PAN are at opposite ends of the triboelectric series and develop opposite charges in needling. This give a more permanent electret effect than is possible with just PP where the opposite charges are on opposite sides of the same fibre.

Micro-Binder fibres can be made by having polymers with widely differing melt temperature:

  • PET/PE citrus fibres can be split in hydroentanglement and thermally bonded. The PE micro-fibres, intimately dispersed among the non-bonding PET fibres give many small areas of bonding and a nonwoven with an unusually good strength/softness balance.
  • PMP/PP citrus fibres would have thermal bondability with even better chemical resistance.

Elastomeric Splittable Fibres arise from segmenting PP or nylon and a thermoplastic polyurethane:

  • These had excellent chemical resistance and could be split using heat alone.
  • Because the spinning process orients and crystallises the PP and not the PU, the heating causes bulking and yields a self-bulking yarn for textile uses. However in staple form, the PU makes them hard to card.
  • If a Y-shaped fibre with a PU centre and nylon tips is made, carding is straightforward, and the fibre still splits spontaneously to give a high bulk nonwoven on heating.

Wet-laying splittable fibres is of course possible, but the dramatic increase in length/diameter ratio as the fibres split means that they have to be cut very short.

This FIT paper dealt only with re-engineering the pie-wedge or citrus section fibres. Similar thinking is already being applied to concentric and sea-island bicomponents.

Prof. Abhiraman of Georgia Tech on the Fundamentals of Polymer Extrusion

If you spin and anneal fast enough in a spun-bond or melt-blown process, even the unstretched fibres will crystallise to give strong high-modulus products. For instance the normally amorphous random copolymer of PET and polyethylene isophthalate, when spun at 6000m/minute with rapid annealing gives a highly birefringent crystalline fibre as evidenced by X-ray crystallograhy. Also, melt blowing PP from dope at 240 oC, with high veolcity air at 177 oC gives crystalline melt-blown microfibres. (This interesting lecture was unavailable in hard-copy and accompanied by minimalist overheads which the author had no intention of sharing with members of the audience.)

Professor Charles Beatty ( University of Florida ) on Polymeric Alloys

Insight into the growing possibility of making valuable products from post-consumer plastic waste, (but not available in print.)

The very properties of incompatibility necessary in splittable bicomponents prevented mixed polymers from being recycled into usable fibres or sheets. The problem lay with the molten blend being a collection of phase-separated domains with little interfacial adhesion. The solution was to reduce the size of these domains by more vigorus mixing and to increase the interfacial adhesion by grafting on reactive groups to bond the dissimilar polymers together. This was now being in a twin-screw extruder-reactor where the molten polymers were mixed and injected with the chemicals needed to achieve in-situ grafting. Maleic anhydride for condensation coupling or free-radical precursors were used to attach graft-compatible side groups to each polymer. These then reacted together in the extruder.

  • Trials with this equipment had successfully made PVC/PP, PVC/PE and PP/PE alloys extrudable as interconnected phases rather than as discreet domains.
  • The approach could also be used to form a PVC skin on PP. At 20% PVC or more in the blend, PVC accumulates at the surface of the PP due to the "surface excess" phenomena, and is firmly attached by the grafting. Could this be a way to make bicomponents with better dyeing and FR properties?
  • The reactive extrusion of the PP/PE mixture gave an almost ten-fold improvement in impact strength compared with normal extrusion of the same mixture.
  • SEM's showed a polystyrene/HDPE/polymethyl methacrylate mixture where the interface between domains appeared to contain micro-fibre bonds between the dissimilar polymers.
  • Polyester/PP alloys with useful mechanical properties heralded the recycling of the ubiquitous polyester pile, polypropylene backed carpet.

Dale Gregory (Consultant) on 30 years experience in Improving Melt-Spun Fibres.

He had just retired from Eastman. His rather theoretical paper led to the conclusion that further PET fibre improvements will result from the quest for ever greater uniformity of orientation per filament and the resulting denier per filament. This could be attained by reductions in variability of melt viscosity, temperature and dwell time within the spin-pack. Outside the spin-pack, along-the-filament variations could be reduced by developing less variable quenching systems.

Dennis Tavernetti (BBA). Keynote Address:"Failure: The Mother of Invention"

He sought to demonstrate that failure, as part of a systematic "trial and error" development process, is essential to progress. With the nonwovens industry in a period of consolidation, with supply exceeding demand, with selling prices and margins falling, it was natural to move to reduce costs. However if investment and R&D were cut, the nonwovens industry would fall into the same trap as the US textile industry.

The correct response was to try to add more value through invention, and to make sure that the inventions provided real tangible benefits without adding more cost than value. The perceived value much loved by "Marketing" led at best to too many "inventions", and hence high patenting and marketing costs for products which would only ever have a short life-cycle before the consumer realised they offered little real value. Edison did not develop electric lighting without numerous failures.

It was important to recognise a failure, to stop wasting time and money pushing ahead on products with dubious tangible benefits and to redirect the limited development resources to more fruitful areas.

Panel Discussion

Dennis also presented a review of the US nonwoven scene for the introduction to the panel discussion:

  • The only growth in North America diaper sales was in Mexico (13% p.a.).
  • Nonwoven use per diaper had increased due to core-wrap, acquisition and distribution layers, and cloth-like backsheet developments.
  • However while demand for these coverstock-type fabrics was running at 200,000 tonnes/year, the supply was 270,000 tonnes/year.
  • Card/latex was massively oversubscribed in 1998 despite its resurgence in acquisition layers.
  • Card/thermal was 30% oversubscribed but had special properties (more textile-like than spunbond) and was expected to be back in balance by 2003.

Frank Harris, CEO of Fibre Innovation Technology gave his view of the next 5 years.

  • He saw further industry consolidation but expected an upsurge of new small companies making unique high-value products.
  • Textile replacement would gather pace, with home furnishings and automotive textiles being vulnerable to hydroentangled nonwovens.
  • Alliances between nonwoven and textile companies could be expected as the textile industry registered the new opportunities for nonwovens.
  • Environmentally driven products and processes would gain ground, but global competition would prevent any significant increases in raw material prices.
  • In the fibre industry he saw increasing demands for bicomponent fibres (F.I.T.'s speciality) and not just for thermal bonding.
  • He was expecting 10-15% p.a. growth for these fibres mainly in the personal care market and in automotive products.
  • Perhaps surprisingly, he saw the emergence of 2 major new fibre types, both polyesters: PTT (poly-trimethylene terephthalate) and crop-based PLA (Poly Lactic Acid). Both would gain ground in conventional textiles before becoming available in nonwovens.
  • Short-cut fibres for airlaying (3-4mm) would grow at 15-20% over the 5 year period.
  • Spunbonded nonwovens based on the newer fine denier, bicomponent, multibeam technologies would grow.
  • Splittable fibres would be used in needling to make new home-furnishing and automotive "textiles".

Lee Sullivan of Freudenberg-Spunweb

expected to see 30,000 tonnes of lightweight PET spunbonds produced in the USA in 2000, and a further 4000 tonnes to be imported. Overcapacity was evident in PP spunbonds, and while PET was broadly in balance, the two new announcements amounting to an extra 6000-8000 tpa capacity would create an imbalance. Heavyweight PET spunbonds, especially in the roofing sector, were facing strong competition from needlefelts and it was in this market that overcapacity was most evident.

Tom West of Dupont Nonwovens

pointed out that sustained growth over many years only arises from constant re-invention of the company. Dupont had been an explosives company in the 19 th C., a chemicals and energy company in the 20 th and was expected to become a Chemistry, Biology and "Knowledge intensive solutions" company in the 21 st C. Furthermore while the 20 th C. had relied heavily on raw materials from oil, next century would see a switch into raw materials from agricultural crops (PLA again).

Like Dennis he was concerned that the US nonwovens industry was not reinvesting enough in new technology and R&D to stand up to the global competition now emerging. Like Frank, he saw growth opportunities in textile replacement and felt elastic nonwovens could hold the key to faster progress. (N.B. Dupont's "Xymid": Lycra overstitching of a spunlaced nonwoven.)

  • How much is Dupont investing in R&D?

A. 5-6% of sales overall and up to 10% in new technology areas.

Q. Why was crop-based polylactic acid figuring relatively strongly in these forecasts?

A. The panel listed:

  • It has a cost-point between nylon and polyester.
  • It has a very cotton-like handle.
  • It is easily dyeable, and has excellent UV stability
  • It is from a renewable resource.
  • It is inherently absorbent and comfortable next to the skin.
  • Dow-Cargill are contemplating a several hundred million pound per year plant.
  • At 300million lbs/year capacity, the costs will be below $2/lb.
  • How big a role would crop-based polymers play in the Dupont of ten years hence?

A. We already have a pilot plant.

Q. Why the investments in China?

A. Not for short-term profit. China might just become the world's largest nonwoven market and being in at the start was good strategy.

Michael Tierney of Morgan, Lewis & Bockius: "Protect yourself!"

US patent law sets certain requirements for the patentability of an invention and the information needed for a patent application. Familiarity with these requirements is important to avoid "patent pitfalls" and to provide sound patent protection for strategic research and development. This presentation gave an overview of the property rights provided by a patent, discussed the standard for patentabililty, and provided various strategies for obtaining commercially effective patents.

"Measuring and Predicting Planar Absorbency Rates", by Bernie Miller of TRI

In Bernie's eyes, Washburn had earned his fame by simply substituting La Place's equation into Poisseules equation. Bernie used the equation, suitably corrected for the effects of gravity, to show that whenever porous structures start to wick fluid, those with the larger pores will always outperform those with the smaller pores. However, past a certain wicking height and time, the smaller pore structures overtake and continue to absorb faster and further than the larger pore structures. So, conclusions drawn from wicking tests over say 2 minutes could be the opposite of those from tests conducted over an hour.

Ram Shet of Technology Forecast Int. ( Neenah ) on the importance of proteins in Femcare:

Both soluble proteins and glycoproteins have a negative impact on the performance of feminine hygiene products. Utilizing the knowledge of protein-polymer interaction in biomedical products, a large increase in absorbency can be achieved by engineering the molecular architecture of superabsorbents in feminine hygiene pads

  • Real urine contains enzymes which breakdown CMC superabsorbents so that even products with good retention under pressure with saline are degraded by urine.
  • Real Menses contain proteins which spontaneously absorb onto any hydrophobic surface. It sticks due to charge, polarity, and increasing hydrophobicity as the protein unfolds.
  • Hard proteins (lysoyme, ribonuclease) absorb under all conditions onto hydrophobic surfaces, but onto hydrophilics if electrostatically attracted.
  • They can be displaced by soft proteins (myoglobin, albumin) which have lower structural stability and unfold much more readily. They absorb despite some hydrophilic dehydration and electrostatic replusion.
  • Whenever blood contacts a foreign material, it coats it with plasma proteins which then dominate all subsequent absorbtion.
  • Experiments studying the interaction of amphoteric polyamide membranes (made from 19.8 micron particles) with Bovine Serum Albumin (BSA) were described
  • The membranes were treated with 0.1 Molar NaOH for times ranging from 5 to 30 minutes to give samples with differing carboxyl levels.
  • Absorbtion of BSA onto the membranes is reduced by the increasing negative charge due to carboxyls.
  • Absorbency of menses on cross-linked polyacrylic acid polymers can be improved by the use of surfactants, amido compounds, organic and inorganic salts.
  • If SAP's are neutralised with K + rather than Na + and to a lower degree of neutralisation, blood absorbency is substantially increased. (The opposite is true of saline absorbency)
  • K + neutralised SAP's give dramatic increases in free swell at 5 minutes immersion but slightly less free swell at 30 mins (c.f. Na +)
  • K + SAP's from the relatively hydrophobic methacrylic acid monomer absorb blood faster (twice the volume in 5 mins) and have only slightly lower free swell at 60 mins (c.f. K + polyacrylic acid SAP's)
  • Kimberly Clark's US Patents 5,241,009 and 5,346,485 (1993-4) were referenced.

Amy Morgan of Fibervisions on Visualising Fibre Finish:

Finish distribution is a key parameter in the absorbency, processability and uniformity of roll goods.

  • Finishes are applied to lubricate, to control fibre-to-metal and fibre-to-fibre friction and to allow liquid management.
  • Finish is applied to PP before and after crimping, the latter to make up for losses caused by heat and steam in crimping.
  • Finish uniformity has proved very hard to quantify with none of the following methods being satisfactory:
  • Web uniformity measurement on the assumption that more even webs result from more even finish. (effected by many factors other than finish)
  • Dynamic absorbtion testing. (multiple water drop test on webs: not good for fast absorbing fibres.)
  • Tow wicking rate and pattern. (Not good for absorbent fibres)
  • Single filament wicking - contact angle measurement. (too small a sample)
  • Friction testing on a running tow. (factors other than finish can effect it)
  • Optical microscopy to see the finish globules. (Better for hydrophobics than hydrophilics)
  • Microfluorimetry, but the need to add fluorescent tracers to the finish is often impractical on production machines.
  • Conventional SEM: sample preparation and high voltages can remove finish globules.
  • Replica SEM: taking a silicone cast of the fibre surface. (Too fiddly and can remove finish also.)
  • Environmental SEM: too expensive.

The proposed solution was not totally convincing but the pictures from the technique were excellent.

She had used a "state of the art" R.J.Lee PSM-300 which is much cheaper than environmental SEM, uses low accelerating voltage, and does not need the sample to be in high vacuum. After easy sample preparation, the finish droplets are clearly visible. Samples taken through processing show the finish being smeared out over the fibre.

In response to questions, she confirmed positive identification of the finish droplets using elemental X-ray spectra on the drops as seen, and that she had done no work on cellulosics.

Airlaid Composites and Superabsorbent Polymers: by Edgar Herrmann, Stockhausen.

Absorbent polymers are one key component in absorbent airlaid cores. By varying SAP types in "modular based constructions", the targeted end-use products can be simply achieved through a combination of different prefabricated constituents. These experiments with their SXM4750 and SXM9100 SAP's in 32 different three-layer composites furnished predictable overall conclusions:

  • The more permeable SAP gave the fastest acquisition and transport.
  • Diaper rewet is better for the most retentive SAP.
  • Densification of air-laid pulp/SAP composites slows their acquisition rate.
  • Densification improves rewet.

Conclusions regarding the layer combinations and mixtures of SAP were less easy to draw, but were said to demonstrate ways of solving individual design problems.

Dr Thomas Fechter of Fleissner on High Pressure Spunlacing

The application of high-pressure hydroentangling systems has opened up new possibilities for product optimization and development.

  • He showed photo's of two of Fleissers installations:
  • A 1.8 metre 5 step (4 drums and a belt) machine with 7 injectors to make 600gsm fabrics.
  • A 2.5 metre 3 step (2 drums and a belt) machine with 7 injectors for lightweights.
  • The water system is cleaned by froth floatation followed by self cleaning sand filters. The sand filters are static-bed unlike (he said) the more fluidised system which Perfojet found leaked fine sand and eroded jet strips at an alarming rate.
  • The froth floatation unit was said to remove fibre finish from the water system as well as fibre debris.
  • They need to use antifoams to prevent foam from some finishes disrupting the sand filters.
  • They use one piston pump per injector.
  • They reduce the hole size to 0.1mm for heavyweights (>200gsm) to avoid flooding.
  • Graphs of strength v speed showed strength reductions in the 100 to 200m/min range which could be corrected by pressure increases. (Below 100 m/min, speed and strength were unrelated.)
  • On heavyweights, an energy input of 200 KW/metre is regarded as the economic limit for HE. Above this, the economics favour needlepunching.
  • The key area for development was nozzle design and perfecting the hole profile to get longer coherent columns of water. (no fanning out)
  • They are working with water additives to improve entanglement efficiency. (Viscosifiers??)
  • They predict being able to install a 5.5metre wide line working at 600 m/min and 600 bar for spunbond. (n.b. This would make spunbonds much more textile-like and could be regarded as the two-dimensional analogue of yarn texturising.)
  • He commented that jet life on viscose was 6 months compared to 1 year on polyester. This was due to 1 micron particles coming off the viscose. Questioning him afterwards revealed that he was unaware of the difference between matt and bright and didn't know which lustre had been used. (The particles were most likely titania from matt viscose being damaged by too high a pressure)

Steve Russell of Leeds Univ. on Structurally-Engineered Air Laid Webs

They had used a high speed camera to observe fibre motion in the 20-year old Kroyer machine donated by BFF. The only interesting observation was that as the web thickness increased, an increasing number of fibres tended to stick vertically in those already laid down. The fact that he had used straight rather than crimped fibres made the observations less valuable.

Advanced Airlaid Composites Based on Superabsorbent Fibers by Ian Cheyne of Camelot.

He showed how product and process simplification coupled with "a superior absorbent fibre" (Fiberdri™) can yield lower cost, more absorbent and more flexible feminine hygiene products. The 3-layer Fiberdri™ pad was compared with 3 commercial pads for cost, acquisition time, capacity, retention, spreading and rewet using saline, synthetic menstrual fluid and bovine blood:

  • The air-laid composite with fibrous SAP had a materials cost no more than the lowest cost commercial product of comparable performance. (he said)
  • Potential for lower capital and operating costs had been demonstrated.
  • Potential existed for distribution cost savings. (30% thinner product)
  • Despite lighter weight, the fibrous composite was ranked first for absorbency
  • The fibrous product was more fabric-like in texture than the competitors.
  • SA Fibres give more uniform air-laying than powders, with less dusting, migration and fallout, better performance on compression and better wet integrity.

Karla Garner of Kosa on Bicomponent PET for airlaying:

They had studied the effects of fibre denier (3, 15 and 32), shape (round, trilobal, pentalobal and High Void), and concentration (12-52%) on the tensiles, bulk and compression resistance of air-laid pulp webs. 6mm fibres with 8-10 crimps/inch had been used throughout.

  • 12% PET doubles the total capacity, doubles the web thickness and nearly doubles the wicking height.
  • 15 dpf appeared to be the optimum denier.
  • Wicking improves with shape: round
  • Absorbency decreases with PET contents above 12%.
  • The more PET fibres (numerically) the weaker the web. (32 denier had least effect at any given concentration.)

Henning Skov-Jensen on the prospects for an Air-Lay Super-Site:

He defined a super-site as a single plant air-laying 100,000 tonnes per year and festooning the output to feed on-site diaper production. The air layer would have a calender to densify the output to 0.4 gms/cc and bond it. He thought it possible that the super site could even be built at a pulp-mill to achieve further integration.

The paper was notable for it's comprehensive breakdown of the manufacturing costs of the super-site revealing the M&J machine would cost $58M. 6000 tonnes of short-cut bico. reinforcing fibre would be needed at an assumed price of $2/kg. The pulp would cost 55c/kg and the superabsorbent (45,000 tonnes/year) would cost $2/kg.

The Regulation of Anti-microbials in Europe by Mike Baldry of MGCB Associates

He reviewed the changes to be expected when the harmonised system replaces a plethora of national regulations.

The new Biocidal Products Directive (BPD), published on April 24 th 1998 is now in force and has to be adopted into the laws of European states by May 13 th 2000. It introduces a 2-layer approval system based on risk assessment for the many active substances and biocidal products which are outside the regulations for chemicals, human and veterinary medicines, medical devices, cosmetics, food, food-contacting materials and plant protection products.

There are many uncertainties for manufacturers and users, however:

  • Biocides used simply to protect a product from microbial attack will be exempt.
    Biocides intended to sanitise surfaces will need BPD approval.
  • The BPD will reduce incentives to research new biocides and their uses.
  • There will be higher costs for data generation, fees and manpower to comply with the directive.
  • There will be higher barriers to entering or remaining in the anti-microbials business in Europe.
  • The Biocides business is likely to become concentrated among the larger companies.
  • Biocides businesses will be similar to agro-chemicals and pesticides businesses.
  • Results from risk assessments under the BPD could affect similar products in other regions of the world.
  • The BPD will represent a much higher hurdle to obtaining regulatory approval than FDA/EPA.
  • The BPD could prove to be a deterrent to imports, and for those products with approval, an incentive to export into regions with lower regulatory barriers. (e.g. Approval in the USA would be cheaper to obtain for BPD approved products)

Roy Broughton of Auburn University on Textiles with Antimicrobial Functionality.

He concluded that the ideal textile anti-microbial - one which kills all microbes which come into contact with it, while being non-toxic to higher life forms and not persistent in the textile-waste environment, does not exist. Developing the ideal is getting increasingly costly thanks to ever tightening regulations.

  • Triclosan, is now widely used in fibres from Hoechst Celanese (acetate), Synthetic Industries (olefin) and Sterling Fibres (acrylic), but is now thought to be resulting in triclosan-resistant bacteria.
  • Biguanides from Zeneca were reported to be available in cellulosic fibres from Acordis® (sic)

    With regard to whether the biocide should be spun-in fibres or added topically to fabrics he commented that it depended on the rate of leaching in the application. (Fast leachers better within the fibre, slow leachers better applied topically)

Saul Schapiro of Textile Biocides Inc. on Dealing with Current EPA regulations.

You can apply for registration by the EPA, but:

  • It will take at least 9 months.
  • The EPA has no protocol for the registration of treated textiles.
  • Much expense, patience and persistence needed to succeed.
  • Have to demonstrate that your product is effective at the 99.9% kill standard. However he commented that this could be relaxed in the interests of assisting the control of current "problem" organisms such as E.Coli, Staph., and Strep., for instance, on cutting boards.
  • AATCC method 100 proves acceptable to the EPA, method 147 does not.
  • Test data has to be from a GLP certified laboratory.
  • There have not been many successful registrations due to the instability of the EPA positions.

You can apply for exemption from the regulations if:

  • The biocide is only to protect the product and,
  • If you imply no benefits to the user.

This exemption route could be a good start, allowing you to market the product while persisting with full registration or "waiting for the law to change!". (A four-page document clarifying the "Treated Articles Exemption" is available appended to the paper.) With regard to terminology, "Antibacterial" is no-longer allowed in a non-public health context, an while "Antimicrobial" is OK, it must be qualified by a statement of what it is active against. For example the FTC are currently "going after" Vaseline Intensive Care Antibacterial Hand Lotion. "Unqualified anti-microbial/bacterial claims will not be tolerated".

Confusion regarding the jurisdiction of the FDA and the EPA is now being sorted out:

  • EPA are dealing with cutting-boards, toothbrushes etc.
  • FDA are dealing with mattress covers in hospitals (but not domestic?)

Processing and Property Studies of Cotton-surfaced nonwovens by Christine Sun of Tandec

She described a Cotton Inc. sponsored project on stretching spunbonds to which PP/cotton blend webs had been thermally bonded. The bonded webs had been stretched to 1.4, 1.5 and 1.7 times their original length, the most notable effect being an almost proportionate increase in thickness and basis weight.

In response to questions she admitted that they had been allowed to shrink in the CD. The other conclusions were therefore less valuable.

"Carding of Microfibres" by Abdelfattah Seyman of NCSU

presented data on processing Wellman's 0.9 dtex polyester on a conventional flat-top card.

The neatly designed and statistically analysed experiments showed that nep and broken fibre levels in card-web could be reduced to acceptable levels by increasing drafting, minimising the fibre recycling (by reducing the doffer/cylinder setting) reducing the feed-roll speed (i.e. throughput), and reducing the fibre length (38 to 30mm). Unfortunately, web uniformity tended to deteriorate, and the only suggestions for improving this were to use a highly opened fibre, and to pay more attention to feed-lap uniformity.

An old textile hand in the audience commented that he used to process 9-10 micron cotton into 120's CC yarns, but only on cards with flexible wire clothing. Clearly many more carding points than were available on modern metallic wire (saw-tooth) clothing were necessary for microfibres.

Thermal Bonding Session

This ran concurrently with the air-laid nonwoven session and was not attended. The papers were as follows:

Doing It With Hot Air by Don B. Gillespie, Fleissner, Inc.

Although bonding is not the only influencing factor in creating a nonwoven product, it is the key element providing strength and performance to a nonwoven. Compared to other bonding processes, thermal bonding provides manufacturers with numerous benefits ranging from economic efficiency to uniformity. (paper absent from the proceedings)

Continuous Ultrasonic Bonding by Frank Simonetti, Herrmann Ultrasonics

The latest technology of continuous high speed ultrasonic welding for nonwovens. This session covered the facts and fictions of ultrasonic bonding and its relationship to other thermal bonding processes.

Heat Generation During Ultrasonic Bonding by Z. Mao & B.C. Goswami, Clemson University

A method for the prediction of heat generation during ultrasonic bonding and its effects on fabric properties.

Nonwovens from Cotton/Cellulose Acetate Blends by Kermit E. Duckett, UTK.

Continued interest in biodegradable/compostable nonwovens has led to the production and evaluation ofproducts containing cotton/ cellulose acetate fibers. By modifying the bonding process suitable fabrics can be produced.

The printed paper indicates that acetone vapour treatment, and aqueous acetone padding prior to calendering improve the strength of the nonwoven, but not as much as triacetin.

CRW 30/9/99