Friday 7 November 2003

Insight - Nashville 19th – 23rd October 2003

More than 500 of the great and good of the nonwoven industry, 50 having travelled from Europe, assembled for 5 days in gloriously sunny Nashville for a conference of 27 sequential papers arranged to allow ample time for questions and networking.

It was the 25th event in this independent series of conferences organised by Marketing Technology Services of Kalamazoo Michigan, and marked a quarter of a century of top-class programmes, always up to the minute and often controversial, arranged by Jim Hanson and his team.

The Evolution of Diapers

Donald Sheldon, VP Absorbent Products of the Tyco Healthcare Retail Group Inc. reviewed the US development of diapers from the 1950’s cloth diaper services through Victor Mills development of Pampers to the present day. He argued that current diapers were too complex, the complexity arising from the limitations of the Pulp/SAP core structure which absorbed too slowly requiring ADL’s and leg cuffs to manage the unabsorbed volume until the core caught up.
He thought future diapers would have a core of SAP and filaments with built in odor management and an SMS backsheet, the whole structure allowing all-over stretch. They would prevent heat build-up and discomfort and would look and feel like textile underwear. Furthermore they would be free of surfactants, lotions and antimicrobials to avoid creating future allergy or resistance problems.
Asked if there was any patent coverage on the SAP/Filament core Mr Sheldon said there were 26 patents* with more to come. What about air-laid cores? They gave no real advantages and required a massive investment to use: maybe $1m/diaper line. Filaments would prove cost-effective compared with pulp, and a training-pant design would gain share in the main diaper market as it had done in Japan.

Absorbent Hot Melts

Pat Kellogg of H B Fuller pointed out the deficiencies of current SAP powders:
  • Most diapers are discarded with some SAP unused.
  • Airborne SAP is a safety hazard.
  • SAP gel on baby’s skin is a concern for mothers.
  • Backsheets are easily punctured by SAP.

    A number of ways of fixing the SAP in place had been evaluated:

  • Mixing SAP with hot melt polymer.
  • Coating SAP with fine hot melt powder and fusing it to the pulp.
  • Adding hot-melt powder to the drum former.
  • In-situ polymerisation of SAP monomers to give a SAP bonded core.

Of these simply mixing SAP with hot-melt looked best if the carrier, application and performance issues could be solved:

  • Water soluble hot melts failed because they competed with the SAP for fluid.
  • EVA was not good.
  • Thermoplastic elastomers didn’t work.
  • But, hydrophilic versions of TPE did.

The form of SAP to be added to this carrier was clearly important:

  • Big particles caused problems.
  • Fines seived from the process were better than normal SAP.
  • Especially ground and sifted powder was best but still not right.
  • So, Fuller developed a new form of SAP.

The resulting “Hydrolock®” hot-melt absorbs 30 g/gm of water in one minute and 30/gm/gm 0.9% saline in 8 minutes. Saline absorbency under load is 28.4 and the lubricity (ASTM D-2266) is <1mm so it should not wear out the nozzles. Flow-rate versus metering pump speed is linear, and when applied by the usual hot melt equipment it sticks to whatever it lands on and stays put.

The benefits: No dusting or sifting, lower waste, faster line speeds possible, lower loadings possible, can apply it where its most needed i.e. leg gathers, thinner backsheets can be used, and super thin pulp-free products become possible.

In response to questions, Mr Kellogg added:

  • It’s not designed to be flushable but it would help design of flushable products.
  • Results with synthetic blood have been variable, but consumer testing has been very positive.
  • No special nozzle filters are needed.
  • Application should be at 250 0C. The product is unstable at 300 0C.
  • SAP/Adhesive ratio? The performance is not based on SAP content alone.
  • Could the SAP separate out? No.
  • The acquisition rate may be too slow for diaper use, except maybe as a leakage barrier
  • It is not recommended as an adhesive. The cohesion is lost in water.
  • %SAP? Not a valid question. It’s a 100% absorbent hot melt.

Polyester for Airlaid

Keith Carnes of Wellman Inc described how the absorbency/retention of air-laid core materials is affected by additions of polyesters of different deniers and in differing concentrations. The studies were carried out on a 12” DanWeb pilot line, the control diaper core being 40% Sumitomo Aquakeep SA55S, 50% Weyco NB416 fluff pulp and 10% KoSa T255 PE/PET bico fiber at 600 gsm and 0.12 g/cc density. An adult incontinence control had the same structure at 250 gsm.

  • Replacing SAP with PET fiber whilst maintaining fabric weight improves absorbency, retention and acquisition time over a range of differing constructions and densities.
  • Reducing the PET denier from 11 to 3 improved absorbency (rate and capacity). The optimum denier may be lower still.
  • Hydrophilic finishes on the PET were better than hydrophobic finishes.
  • If core weight is reduced by substituting PET for pulp, absorbency generally improves.

Mr Carnes concluded that further studies with finer PET fibers, different finishes and higher PET levels were now needed. He also mentioned a new absorbent polyester, a copolymer with polyethylene glycol, which had a contact angle of 54 0 compared with rayon’s 58 0 (his measurement) and regular polyester’s 76 0 . It also showed a diameter swelling of 20% on wetting and was now being patented.

Hydrogen bonded Airlaid

Krishna Kumar, Manager of R&D for Novathin at Rayonier Corp. sought to dispel concerns about the stiffness, strength and absorbent rate of their hydrogen bonded air-laid cores.

  • The compression modulus of a 200 gsm core with 25% SAP could be reduced from the normal 5.5 N/mmto 2.5 by changing the process options and to 1.3 by changing the raw material options. (Gurley stiffness down from 350 to 255 gf.)
  • Third insult acquisition time could be reduced from 45 to 19, 14 or 11 seconds by three separate approaches to improving on the control.
  • Elongation could be increased from 3% to 11% and tenacity from 19.5 to 23.5 N/5cms while reducing density from 0.33 to 0.27 g/cc by two other approaches.
  • For a 400gsm core with 55% SAP, thickness could be increased by 50%, strength by 15%, and third insult acquisition time reduced from 33 to 23 seconds.

In summing up, Mr Kumar said that Novathin was now available in weights from 80 to 700 gsm, with densities of 0.1 to 0.45 and containing 0 to 70% of SAP. Novel forms of pulp were now being investigated. What about pre-formed diaper cores? The current value proposition was better performing cores at the same cost as the on-line cores.

Bico Fibers for Airlaid

Ida Pittman, a Senior Development Engineer with Kosa showed how their Type T255 PET-Core, Co-PE sheath bico gives the highest strength bonds to woodpulp while T254 with its Co-PET sheath gives best bonding to polyester. When bico contents are below 15%, pulp-bico bonds predominate in defining the strength, whereas above 15% bico, the bonds between the bico fibers predominate. 15% is therefore the concentration of bico which in these trials gave the most variability in web strengths, so 20% or above is recommended. Interestingly, this “transition concentration” was different for different fiber types, and so needed to be determined for every web type. Other conclusions from the study:

  • Tensile strength of the pulp/bico blends is affected most by basis weight, then by bico concentration and bico length; bico denier being least important.
  • 20% 4mm bico gives the same strength as 10% 8mm bico.
  • Reducing the bico denier from 2.8 to 1.5 increases strength by 50%
  • Replacing a sixth of the bico with solid PET fibers yields a softer more resilient web without loss of tensile.
  • Hollow PET gives more bulk.

In response to questions, crimp effect had not been studied, some hydrophilicity is lost as the sheath polymer melts, but Kosa use finishes designed better to stay on the surface. Asked if density had been held constant throughout the trials, Ms Pittman said it had not been deliberately varied.

Agricultural Airlaid

Annette Skyt of Dan-Web Holding’s Dan Core division argued that there may be a case for smaller air-laid lines than those that had created the global oversupply situation. Lines of 1000 to 4000 tpa output in widths from 250 to 1200 mms would be good for a variety of niche products and would be cheaper to install and more flexible in use. For instance, Kinsei ( Japan) use a narrow Dan Web line to:

  • Incorporate orange-juice manufacturing waste into an air-laid web for use as an agricultural mulch.
  • Incorporate green tea leaves, bean curd or bamboo into air-laid for use as cat and dog litter. (These bio-wastes all have a natural absorbency and ability to control bacterial growth and odor.)
  • Make 8gsm 100% synthetic fiber nonwovens for roofing lining and tea-bags. Make 700 gsm synthetic fiber nonwoven from 72 denier fiber.

Also in Japan cheese, bread and milk packaging is being made containing natural moulds to inhibit bacterial growth, and sushi trays are made to inhibit the odor of fish.
In Denmark, wood fibers reinforced with longer natural fibers (e.g. coir or straw) are air-laid and bonded with glue and/or bico fibers to make moulded furniture components. Air-laid wallpaper is also made using 76% Weyco NB416 bonded with 10% Trevira 255 bico and 14% Airflex EP 1188 latex at 118 gsm. The same product is selling as an air-filter, and a lightweight version makes an interesting Oshibori.

Patterned wires from Cofpa allow the forming of individual meat-pads which avoid the problem of SAP in the seams.

Dan-Web’s new inverted air-former lays onto a small transfer conveyor above the main conveyor and allows air-laid to be combined with impervious layers such as film. It can also be configured to lay dry pulp ontop of wet laid pulp above the forming wire of a wet-lay machine.

Absorbing liquids, odors and gases

Steven Bullock, an R&D Section Head with Procter and Gamble’s Babycare and Femcare division , responsible for out-licensing P&G’s technology introduced the absorbent laminate structures (ALS) developed to provide ultra thin femcare cores with built in odor control. This technology, developed in Pescara Italy, sandwiches a core of SAP, odor absorbent and hot melt particles between two nonwovens or tissues, bonds the core and seals the powder-free edges. The bonding powder does not affect the functional powder’s absorbency, and the resulting pads are soft, thin, flexible and easily made at high speed. Powder-free edges are achieved by laying the powder in stripes or rectangular pouches on a nonwoven, followed by heat treatment and hot-melt gluing the top layer of nonwoven in place.

The resulting pads can be 25-1500mms wide and filled with 8-700 gsm of up to 6 different powders of 50-600 microns diameter. The strips can be festooned or reeled. Functional absorbents could be SAP’s, active carbon, zeolite, baking soda, silica gel, potassium permanganate etc. Fruit preservation was mentioned as a novel new possibility. Tomatoes and bananas stayed fresh longer on ALS sheets containing permanganate and zeolite.

Femcare aside, P&G’s consumer testing had shown that the top 5 potential applications would be in fridges, garbage cans, shoe cupboards, shoe insoles and in gym-bags, and all those whose opinions were sought expressed a wish to buy such products. P&G had however decided that such products were too “nichy” and were therefore looking to licence the technology.

In response to questions:

  • BBA were already producing the material for P&G panty liners and “special negotiations” would be needed for any licences in the femcare area.
  • Active carbon is not used as an odor absorbent for femcare.
  • Particle size was not too critical a factor in performance.
  • The products did not have FDA approval for direct food contact, but because the actives would not be in direct contact with food, this was not perceived as a problem.

Hydroentangled Spunbond

Frederic Noelle of Rieter Perfojet having recently shown how hydroentanglement could improve the bulk and softness of a fully bonded spunbond now described how hydroentanglement at a very early stage in the process could give fabrics similar to staple products. Previous attempts to HE spunlaid products had taken the consolidated (but unbonded) web from the forming conveyor into the HE bonding unit on a second conveyor. The new Spunjet system positions the HE bonder above the forming conveyor allowing the unconsolidated web to be bonded. The result is efficient bonding at much lower water pressures, and hence thicker fabrics with a better softness/strength balance.

Hydroentangling Spunbonds: Water Pressure versus Strength

Compared with conventional thermal-bonded spunlaid, degradation of fiber strength at the edges of the bond-points is eliminated and the bulk and porosity of the fabric is improved by the absence of the ~20% film-like bond area. Compared to needlebonded spunlaid, finer fibers can be bonded at much lighter weights. Compared to any carded products, spunlaying allows the production of nonwovens with square properties (MD=CD) at higher productivity.

The new process has worked on a commercial scale, i.e. 3.2 m width, running at 400 m/min to give 12,000 tpa output. The machine could spin PP or PET containing additives or colors in deniers between 1 and 6 and in weights between 15 and 600gsm. Patterning of the bonded webs with logos etc. was possible. The line will be commercially on-stream by the end of 2003.

Asked if woodpulp or rayon could be incorporated, Mr Noelle said they were working on this. The high strengths from low water pressures are possible because the web had very low cohesion when it was bonded. The bulk arose because the filaments were effectively crimped by the looping action of hydroentanglement. Water filtration was not an issue, the filaments being perfectly clean and finish free.

Global Diaper Survey

Blake Kuster of Absorbent Technologies Inc reported results from a Sumitomo Seika Chemical Co. study of 110 diaper types from around the world. In addition to core structure, static absorbency/rewet testing of the products had been carried out:

  • % SAP ranged from 42% in Japan down to 23% in the Middle East with North America (36.5%), Europe (29.3%), South America (26.8) and the rest of Asia (26%) in between.
  • US diapers are the fastest absorbers, the Japanese products appearing to have been designed to give a slower uptake.
  • US diapers have the lowest rewet on average, but a UK private label product was best of all in this regard. Asia-Pacific products had the highest average rewet on these lab. assessments.
  • The newer perforated film ADL’s look good especially with lower SAP levels.
  • SAP containment is still an issue with dusting and pinhole problems especially in private label products containing more than 35% SAP.
  • Best performers are not necessarily those with most SAP. 25% SAP efficiently blended and positioned can more than satisfy absorbency demand.
  • From a briefly shown master chart of Rewet v %SAP, a Japanese sandwich-type diaper coded DSG4 with 3gms rewet at 16% SAP looked the most remarkable. At the other end of the scale a product coded KC2 with 25% SAP gave a 39 gm rewet. Heavier (>30gsm) ADL’s are needed to get the best out of ultrathin or low SAP cores.
  • >70% SAP Possibilities? Only if the current SAP structure changes. Current SAP’s are too coarse and harsh for comfort.

Hygiene Products Material Changes

Pricie Hanna of John R Starr Inc reviewed recent changes in the construction of selected hygienic absorbents:

  • K-C’s “Convertibles” used wide-stretch side tabs sonically bonded, and a stretch laminate waistband on a product which could be used either as a pant or as an open diaper.
  • K-C’s “GoodNites” with “Trimfit” discreet youth incontinence underpants used a highly densified core with increased SAP and a lofty carded, through air-bonded ADL.
  • P&G’s “Pampers Easy-Ups” now had wetness indicators to facilitate potty training and the child’s awareness of wetting.
  • Kao’s “Merries” had a versatile mechanical fastening system which could be fastened at the front or the back.
  • P&G’s “Always Maxi Pad” now had an extra absorbent layer, an airlaid ADL which reduced leakage.
  • SCA Hygiene’s “Libresse Goodnight” pad has an elastic band extended lengthways under the core for better body fit. The core is wide in front, narrow at the crotch and split in half at the (wide) back.
  • SCA’s “Libresse with Invisible Wings” is an ultra-thin pad with transparent film barrier, backing and wings for maximum discretion.
  • SCA’s “Libresse 2 in 1” is an ultrathin panty liner with the absorbency of a napkin.
  • SCA’s “Libresse So Slim” is an ultrathin panty liner daily alternative to extra panties when travelling.
  • SCA’s “Libresse Micro” is a very small oval liner in a hard plastic container for everyday use in most panty styles.
  • Walmart’s “Assurance Refastenable Underwear” can be pulled up like underwear or changed like an open diaper without removing clothes. It uses an apertured film ADL.

For improved leakage prevention, fluid transport and absorbtion systems are being optimised, extra leg cuffs are being added and improved elastics and elastic fabrics are being developed.

For increased convenience and ease of use, look out for pull-ups with openable sides, adjustable side panels, and easy-to-grip tabs.

For increased comfort, softer spunmelts and lighter nonwoven/film laminates are being used, elastics are getting gentler and cores are getting thinner and hence better fitting due to >50% SAP and improved ADL’s. New film/nonwoven laminates are being used to improve air-flow and hence skin health. For discretion, quietness (softer films) and odor absorbency (modified SAP’s) are being added to the above material changes.

Asked if the pharmaceutical companies would win over disposables, Ms Hanna said that John Starr Inc had helped them understand the market. Pharma solutions appeared to very specific to each of the many causes of incontinence, whereas the disposable products could be applied to all.

She felt that the 8-hour, $5 diaper proposed by Ms Ericksen would be too specialised for the major producers but may be developed by an entrepreneur.

The average SAP content in diapers was now 48%. Next year premium products with 70% SAP would appear.

The wipes market continues to grow as fabric qualities are upgraded. Some of the newer household wipes are showing impressive staying power.

Pharmaceuticals threaten Disposables?

Helena Engqvist (Consultant) warned that the pharmaceutical industry with its massive R&D capability and desire for double-digit growth was beginning to develop products which could reduce the need for hygienic absorbents.

  • The Seasonale® drug now on the market reduced the number of periods a woman had per year from 13 to 4. If generally used this would have a dramatic effect on the $18bn disposable femcare industry.
  • Adult incontinence, a $6.3bn market in 2002 is being targeted with oxybutylene patches which now have approval for over-the-counter sales.

The pharmaceutical industry has been successful in redirecting its marketing effort from healthcare professionals to consumers and this will continue.

No child left behind - given 8 hour diapers

SusanEricksen, a Special Needs Educational Co-ordinator highlighted the problems of coping with the incontinence of handicapped children in schools in the USA. The time and costs of diapering were significant. Handicapped children attended either Center Based Programs or Public Schools:

  • For the Center Based Programs she had calculated that it costs about $7000 to equip one room with the tables, lifts and bolster to allow 2 assistants to change the diapers of the 12 children in the class. Monthly cost of disposables amount to $256 (paid by the parents of each child) and staff time required amounts to one full-time person, or $2120/month. Furthermore, each child loses 40 minutes of education per day to diaper changing.

  • The 30,000 multiply-handicapped incontinent students in mainstream US schools change their own diapers, but this takes longer, so they lose 80 minutes per day of educational time or 40 days/year. With each change costing $3.18, the cost per day amounts to $763,200 in the US.

Ms Ericksen made a case for diapers specially designed for these students, a key target being a product which would keep them dry and odor free for the full 8-hour school day. Such a product would be worth at least $5 per diaper, and would, as a much-improved training pant, command a larger market than she had calculated for this paper.

In response to questions: Yes, reusable products would be acceptable. They would have to be sized to fit students up to the age of 26. They could be distributed with the other “special care” needs of the educational system or over the internet.

Chlorox Wipes Case Study

Andrew Kilkenny and Garry Embleton of Chlorox Services Co. pointed out that the early antimicrobial wipes, Dow “Spiffits” and Chlorox “Spruce-Ups” failed because they overpromised and underperformed at a time when consumers were not so aware of the benefits of disinfection and convenience as they are now. So Chlorox reformulated and relaunched in Jan 2000, a week ahead of the competition, the resulting demand exceeding all expectations. The key to their success was collaboration with suppliers:

  • They ran 32 wipe constructions in consumer tests to ascertain aesthetic and performance preferences.
  • Nonwoven type, Embossing and Binder levels were among the variables studied.
  • Cleaning, Disinfection, Absorbency and Dispensability were among the attributes monitored.
  • The suppliers who provided the fabrics were allowed direct access to the consumers used for the panel testing.

Contract packers are used for their speed and flexibility compared with in-house converting. These were most helpful in dealing with early complaints related to roping, excess wipe left out of the canister, and fallback into the canister. They reoptimised the perforation pattern and developed a new closure system which allowed storage of excess wipe. Problems with the “logs” collapsing in transit and storage were dealt with by a move to a stiffer substrate.

The success of the relaunch was sustained by introduction of new varieties:

  • Thicker/larger wipes
  • New Fragrances
  • Flushability (for toilet wipes)

Chlorox are looking for new partnerships with suppliers and this appeared to be the main motivation behind the presentation. They feel their “both parties win” approach gives the supplier a proper return for providing a “total value package”, i.e. innovation, low costs, service and high quality. They look for two types of supplier:

    • Cost and service driven (Low R&D%)
    • Innovative suppliers (High R&D%)

Most suppliers are somewhere between these extremes.

Their “Technology Brokerage” manages the R&D relationship with suppliers, and R&D pervades all aspects of the collaboration. An “R&D relationship owner” works with procurement and the supplier to ensure Chlorox is exposed the suppliers full capabilities. They have also developed a quantitative supplier performance assessment and use this to push opportunities towards the high performing suppliers.

In response to questions:

  • Should these relationships with suppliers be exclusive? Yes, and furthermore Chlorox would like a share in any intellectual property they develop.
  • Their flushable product is pulp based, and the flushability claims are based on a dispersion test.
  • Wipes account for 10% of Chlorox turnover, but Chlorox now have 16-17% of the wipes market.
  • They have developed their own wiping tests and “soils”.

The Wipes Market

Susan Stansbury of Arketype Inc provided the latest data on the wipes market:

  • INDA put the 2002 North American market at $2.2bn whereas Paperloop estimated a $1.5bn demand.
  • Baby wipes were 55% of the total, the rest being 14% Personal and skin care wipes and 31% household wipes.
  • North American demand for spunlace was now 100 – 120,000 tonnes/year. Half of this was for wipes, and ~35% for medical.
  • The key US producers of spunlace were Dupont, BBA, Green Bay Nonwovens, PGI and Ahlstrom. K-C made it primarily for their own use.
  • Airlaid capacity in North America was ~250,000 tonnes, some of this underutilised.
  • 60% of the airlaid is in wipes, with Georgia Pacific Nonwovens having the strongest position.
  • The wiping sector is set to grow at 6-7% pa for the next 5 years, with 15% pa growth in some niches.
  • New wipes continue to emerge, e.g. pet-care, body wipes, antibacterial wipes, and insect repellents.
  • Dry wipes typically compete in Food service and in the $1.5bn industrial sector, 32% of which is now disposable rather than reusable products. Most growth is expected for spunlace replacing the reusable shop towels.
  • Dry wipes have about 30% of the total nonwoven wiping market and do not grow as quickly as wet wipes.
  • Chemically treated versions (delivered dry for wet use) are set for above average growth and could take share from their wet counterparts. (Easier to make and cheaper to deliver. No bioburden issues)

Asked to name some fast-growing niches, Ms Stansbury said many were auto-related. New players , probably contract manufacturers teaming up with marketing companies to make private label products, would enter the field.

PP for Wipes

John Wolhar, Americas Sales Manager for Fibervisions made a case for replacing the viscose in wet-wipes with their newly developed HyEntangle WA fiber. PP has the inherent benefits of low density (more fibers/gm), low melting point (easy embossing), whiteness c.f viscose, cheapness, softness, and excellent chemical resistance. Their older HyEntangle fiber had a specially low dtex, higher tenacity and a low-foam finish and has now been optimised to improve production economy and wiping performance.

Because PP fabrics do not collapse when wet, the 100% PP wipe stays bulkier and maintains a higher wet CD strength. Absorbency and wettability tests carried out with 0.5% detergent solutions looked good. Furthermore because the absorbtion was entirely inter-fiber, 100% PP gave better lotion release than viscose containing wipes.

Does the finish survive hydroentanglement? Yes, for the newer WA fiber.

Is the wiping efficiency as good as the rayon containing products? “It should be OK in wet-wipes”.

IR, RF and Hot Air

Ben Wilson, Sales Manager of PSC Inc pointed out that both radio frequency and infra-red drying needed air-flow to carry the evaporated water away from the drying zone, so combination dryers would be the best solution to most drying problems.

  • Hot air dryers were best for holding a product at a temperature for a long time without overheating.
  • IR was best for rapid heating of the whole web.
  • RF heats the center of a fabric before the outside, while IR does the opposite.
  • RF also heats the water preferrentially and dries the wettest parts of a web or fabric first. It therefore removes damp spots and can be used to reduce the variations in moisture content at the end of a hot air or IR system.

RF heating depends on the loss factor of the material in the dryer, but loss factors change on heating. So PP is not sensitive to RF until its temperature goes above 250 0F and then runaway heating leads to meltdown. RF with cool through air drying would be best for such products.

Ultrasonic bonding revisited

Torsten Brieger of Hermann Ultrasonics Inc described how their micro-gap control system is making sonic bonding consistent enough for the most demanding welding and bonding applications. Stepper motors are now used to change the weld-horn position in 0.4 microns steps to compensate for thermal expansion of the titanium horn or variations in thickness of the webs or fabrics. The stepper motors respond to signals from load cells in the actuators allowing constant welding force to be maintained over widths up to 3m and at speeds up to 500m/min. Compared with calendering the ultrasonic approach is a low energy cold process which gives full bond strength instantly, allowing webs or multiple layers of prebonded fabrics to be welded with precise bond points.

Speciality Meltblowns

Mr Soichi Obata of Kuraray Saijo Co Ltd said that his company makes meltblowns from PP, elastics, adhesives, PBT, nylon and composites in the form of a spunlace/meltblown/spunlace laminate. They have now added two new polymers, a polyarylate and a novel polyamide to their range.

The polyarylate is a liquid crystal aromatic polyester (“Beltron®”) made from 2-hydroxy-6-naphthoic acid and 4-hydroxybenzoic acid. A filament version has been used to make the airbags of the Mars Lander, but the meltblown version comprises 4 to 7 micron continuous filaments with a melting point of 300 0C, or 340 0C - for a “heated” version. Other properties to note:

  • 100% strength retention over 72 hours at 200 0C
  • Better than 84-94% strength retention in Normal solutions of hydrochloric, nitric and sulphuric acids over 100 hours at 90 0C.
  • Uniform 15gsm fabrics are possible c.f. a 22 gsm minimum for aramid papers. 10 gsm is targetted.
  • Fabric water absorbtion of 0.1% after 170 hours at 90%RH c.f. 2.5% for aramid papers.

The second new polymer was a polyamide based on nonanediamine and terephthalic acid. Standard meltblown from this had 2-5 micron fibers and a soft handle, whereas a high density version used 9-11 micron fibers calendered into a paper-like sheet. It had a high resistance to caustic, the tensile strength increasing by 20% after 50 hours in N NaOH at 90 0C.

In response to questions:

  • They expected applications in heat and chemical resistant filters.
  • They would not sell the polymer pellets for others to convert.
  • Polyarylate meltblown would cost ~$90/kg, the cost of the polyamide was not available.

Hygiene Market in Eastern Europe

Krystyna Jozefowicz, Manager of the Foreign Trade Dept. of Poland’s TZMO SA described how the company had evolved from a state-owned surgical dressing manufacturer into the leading producers of hygiene products in Poland. In 1991 the 800 employees bought the company and have since grown to employ 4000 people today. They have 67% of the Polish market (P&G ~20%) and have successfully expanded into the Ukraine and Russia. She was concerned that European Integration would leave Russia, Ukraine, Kazakhstan and Belarus out and predicted that these countries would form a new economic block of 205 million people because they would not accept “waiting list” status.

Surprisingly, she claimed that the hygiene markets in Eastern Europe were now mature and saturated.

Cytotoxicity Testing

Eleanor Sun (Consultant, recently retired from PGI) explained the test methods and their current importance.

  • Cytotoxicity arises from biologically harmful extractibles in the materials.
  • The test is suitable for detecting subtle changes in raw materials, vendor differences or process deviations.
  • It correlates well with animal testing and reduces the need for such testing.
  • It is now mandated for all medical devices such as menstrual pads, tampons and incontinence products.

The most commonly used version of the test is the MEM (Minimum Essential Medium) Elution test where the the medium contacts the material for 24 hours and the any change in the mediums ability to culture cells is visually assessed. Mammalian cell culture medium is preferred as this extracts substances which are not soluble in water. Antibiotics can be added to suppress the effects of microbes.

L929 mouse fibroblast, rabbit cornea or human embryonic lung cells are grown in a flask and challenged with the extract. Changes in the layer of cells are observed over three days and damage rated on a 0-4 scale. Dyes such as tryphan blue stain dead cells blue and live cells yellow to help the rating process.

0 – no visible effects
1 – Slight changes, <20% of rounded cells and some lysis (cell walls destroyed)
2 - Mild effect, <50% rounded but no holes in the layer
3 - strong effect <70% rounded or lysed: holes appearing in the layer
4 – Severe effect >70% destruction of the layer.

0 and 1 would pass, and the product would be worth more thorough safety testing using more costly techniques. 2 would be borderline and require further cytoxicity study. A result of 4 would be followed by repeating the test with progessively diluted extract to define the “no-effect” level.

Hydrophilic finishes, lubricants, antistats, wetting agents, colorants and antimicrobials can all cause cytotoxicity.

A cytotoxicity test costs about $100 (24hr) to $300 (72hr)

New Airlaid Pilot Line

Jim Hanson of MTS Inc has a new air-laid pilot line under construction:

  • It is 0.6m wide with 5 DanWeb heads and space for other formers.
  • The 5 forming zones each have their own hammermill, fiber and SAP feeders.
  • One of the spaces could take a head capable of laying 30mm fibers at high throughput.
  • Latex (one side only) and thermal bonding options will be available from the start.
  • Calender lamination of film to the airlaid will be possible.

Clearly a very wide variety of multi-component multi-layer composites will be possible on this machine which will be available for hire in the new year.