Thursday, 6 July 2000

Nonwoven Network Meeting

PLA Fibres
Jim Lunt of Cargill-Dow Polymers gave the presentation on Poly Lactic Acid fibres. Most of the information had already been published, the following points being worth noting:
- PLA USP: "The only melt-spinnable natural-based fibre."
- CDP think they will need an FTC classification other than Natural, Synthetic or Regenerated. (It’s a synthetic polymer, the monomers for which are obtained from a renewable resource.)
- They are not allowed to claim biodegradation in the USA because the composting infrastructure needed to deal with it does not exist.
- The current 4000 tonnes capacity is being stretched to 8000 tpy ahead of the Blair plant coming on stream.
- They claim to be able to use any carbohydrate and foresee future plants installed in developing countries to use any biomass.

Mr Lunt was wearing a PLA/Wool blend jacket with PLA buttons. PLA golf shirts from Kanebo were passed round along with some knits that looked and felt like microfibre filament polyester.
He admitted PLA (M.Pt. 175oC) could not be ironed successfully: a serious disadvantage in textiles. In mitigation, the fibre, like polyester, was essentially non-iron.
They were developing a 210oC M.Pt version based on a polymer with alternating D and L units - "A stereo complex with interlocking D and L structure." This would be available in 2 years.
PLA does not support bacterial growth and only degraded in composting after hydrolysis at temperatures above 60oC.
Yoghurt pots branded "Danone - Jahreszeit" had been test marketed in Germany: they disappear in 47 days in an composter.
100% PLA teabags are on sale in Japan: from the slide they looked exceptionally uniform. (maybe they were very the woven filament bags used for premium tea-bags.)
PLA has the lowest refractive index of all fibres and hence dyes to very brilliant colours.
With a limiting oxygen index of 26% it is essentially non-flam.
It is unaffected by UV exposure.
Interface, the carpet company were said to have made a great success of PLA in carpets.
He said price would be 50 to 100c/lb with the lower figure being possible but unlikely until cheaper biomass sources become usable - i.e. not from Blair. He confirmed the existence of an exclusive users club with the available fibre rationed between the club members who pay to have access to samples. Blair would be expected to produce 140,000 tonnes of resin and would supply 10 club members each having access to 15,000 tonnes. The paper is on the website.

Oasis Update
Bill Brunskill of Acordis’s Technical Absorbents (JV with Ciba) reviewed progress with the “Oasis” superabsorbent fibre. The main applications were listed as: cable-wrap yarns, ink-jet pads, Tatami mats, secondary medical dressings, meat and fish tray liners, femcare, cooling bandages and coffin liners.
Products said to contain “Oasis” were circulated for inspection. They included panty-liners with two-part topsheet (a prettily patterned dri-weave target area with soft thermal bond - maybe hydrophobic - at the sides: maybe from P&G).
A detailed comparison with Lanseal (Toyobo) and Fibersorb (Camelot) showed Oasis™ to have the best balance of Free Swell, Retention, AUL, Centrifuge Retention, and Gel Retention results.
Companies mentioned either on slides or on the sample labels were Geca-Tapes for cable wrap, Zorba PLC for meat packs, Dyecor Ltd, and Conveen (inco pads). A written paper was not available.

Wet Laid Specialities
Nigel Walker of Technical Fibre Products reviewed the wet-laid nonwoven niches where they currently have thriving business:
Fibres laid: Ceramic, Zirconia, Microglass, Rockwool, Basalt, Pitch and PAN Carbon, Carbon whiskers, Nickel, Copper, Silicon carbide, Aramids, PVOH.
They produce 500mm to 1700mm widths, 5 to 2000 gsm and down to 5kgs in batch size.
They design and construct their own formers. (Thermal Ceramics Inc. in the USA has one.)
The main applications mentioned were:
battery separators for lithium and silver-zinc batteries.
8 gsm cryogenic tissues free from all organic matter and suitable for use in high vacuum (negligible outgassing at the molecule level)
High temperature insulation (up to 1600oC with alumina papers)
Fire-protection with intumescent papers (Expands 20x - “Thin ‘til Hot”). Fitted to doors, ventilators and pipes, they seal them up in the event of a fire.
Composite manufacture: they make the mouldable sheets for the IBM “Think-Pad” computers, EMI/RFI shielding & “Signature management” mouldings (Stealth)
They recently signed a JV with Johnson-Matthey to make membrane electrode assemblies for the polymer electrolyte fuel cells said to be capable of replacing petrol engines.

Resilient Waddings
Terry Saunders, MD of GTM Georgia USA, sells a system for making high loft waddings by pleating card webs prior to through-air bonding. The resulting fibre orientation is largely Z-direction, the products being 15 to 40mm thick. After bonding, they can be sliced down to as little as 3mm thick. (this seems to be the old Corweb process used to make the superabsorbent cores of the original J&J “Serenity” inco-pad.)
They claim fourteen of their machines are either running or on order. A 3.2 metre line is being constructed in the UK. Eight m/c’s were sold in the USA last year.
The pleater and bonding oven cost $360,000 but a full line would cost $1.3M. The main products seemed to based on waste fibres mixed with 20% bico to allow through-air bonding.
Waddings illustrated were made from textile waste, shoddy, PES, cotton, and waste coverstock. Weights were from 100 to 1600 gsm.
Applications claimed were: Liquid and air filters (very low pressure drop arising from the axial fibre orientation as in a cigarette filter), mattress pads, automotive waddings - insulation, foam replacement, trunk liners - “GM love it”, sleeping bags - “Doesn’t bottom out on compression”.

Tissue Culture
Dr R J Minns, a consultant clinical scientist in the Department of Medical Physics at Dryburn Hospital Durham, has been using textile implants to encourage the growth of new tissue in vivo. Rough hydrophilic, electronegative surfaces appear to be preferred by the fibroblasts responsible for new tissue growth: carbon fibre being better than polyester or PTFE. Hernia reinforcement, pressure sore repair and articular cartilage resurfacing have all been successfully demonstrated using carbon fibre woven/nonwoven composites. He foresees the use of carbon fibre pads to encourage new cartilage growth in joints taking over from hip-replacement operations.

Needle Design
The Foster Needle (George Swarbrick) paper on needle design reviewed the field. Points of interest were:
Needles generally have 9 barbs but in most operations only the bottom 6 ever contact the fibre. 6-barb designs would be shorter, stronger, cheaper and less likely to break. Customers were however resistant to changing from the traditional 9 barb design.
Different designs needed for different fibres. (Glass, Kevlar, Ceramic mentioned).
Rapid growth in felt/clay/woven PP composites for landfill liners. The clay is wetted before needling. Some producers now use 21-barbed needles for these products.
Jute/grass-seed/jute composites were now being needled.
Woven upholstery fabrics are being needled to raise a fuzz on one side to get better adhesion of a subsequent coating.

Landfill Liners
Dave Walmsley of the Environment Agency described the QC procedures required to allow landfill liners to be qualified. Landfill management is a comparatively recent phenomena in the UK, commencing about 15 years ago when problems with leachate began to be understood. If there is no natural clay layer at a prospective land-fill site a liner must be fitted, and this must contain the leachate for very long periods under pressures of some 20-30 tonnes/m2. He expected UK landfilling to be phased out over the next 20 years in favour of recycling, with householders being expected to sort waste into numerous categories prior to collection. Once the recycling infrastructure was in place he saw old landfill’s being mined for reusable waste.

DTI Grants
Dave Groffman of the Department of Trade and Industry listed the numerous grants currently available to small businesses. They included grants as low as £2500 to allow companies with fewer than 10 employees to use consultants to help write the feasibility studies needed to apply for larger grants!

Recycled PET Spunbonds
Mechanniche Moderna’s paper on spunbonds from recycled PET was in fact an advertisement for their entire PET spinning machine range. Recycled PET has to be dried to below 30ppm water to avoid degradation. Intrinsic viscosity of the resin falls by 0.01% for every 16ppm water. (The written paper was a collection of slides on an apparently unrelated subject.)


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