Friday 7 November 2008

European Bioplastics Conference – Berlin, November 2008

Key Points

· Bioplastics production is growing at the rate of 20% per year in the EU from a low base of 1% of total plastics.
· At this conference the main areas of interest were packaging and those biopolymers being made from annual crops.
· Legislation favouring bioplastics packaging is emerging and bioplastics will be exempt from, or attract lower levels of, the proposed carbon/litter/waste taxes.
· Products made with renewable raw materials could be labelled with a “% biobased” logo, the % being based on C14 assessment of fossil carbon levels.
· There is no shortage of land in the EU for crops dedicated to biopolymer production, and no evidence that biopolymer production will impact food prices.
· A new 60,000 tonne PLA plant is under construction in Germany using Inventa Fischer technology. IF estimate a 700,000 tpa potential for PLA plastics in the EU, and expect the polymer from the new plant to cost between €1100 and €1300/tonne.
· PURAC forecast a 250,000 to 500,000 tonne annual production of PLA by 2015. They are partnering with Sulzer and Synbra to produce a PLA foam from their own lactides.
· Dow are getting into a position where they can react to increased demand for bioplastics. They are already committed in JV’s to make polyethylene from sugar, bio-based polyols, and bio-based epichlorhydrin.
· Kaneka has developed a PHBH foam with properties similar to PP foam.
· Roquette Freres, who process 3800 tonnes/day of cereal into starch, sweetners and polyols, see starch replacing naphtha for polymer production.
· Polybutylene succinate, developed from glucose by the US DoE, is emerging as a promising biopolymer, both alone and compounded with starch, PLA or PHA.
· Cellulose diacetate film is replacing polypropylene for fresh food carton windows and retailers laminated print media.
· Dupont’s flushable Biomax® TPS is being used in tampon applicators, and FKUR’s Bioflex® PLA compound film is being used in diaper backsheets


This was the third annual conference on EU Bioplastics. These have consistently attracted over 300 delegates, the majority being interested in packaging applications. They are organised by the Berlin-based EU Bioplastics Association, which has some 70 members. Interest in bioplastics has mushroomed since the increase in oil price in 2007, and according to Dr Harald Kaeb, the general secretary, this year’s conference has attracted more major petrochemical companies than the others.

Keynote Speech

Kai Wagner Deputy Head of the Division Protection of Natural Resources, Energy Taxation and Water Management of the German Federal Ministry of Economics and Technology observed that 2008 had been an extraordinary year for bioplastics. They were now growing at 20% per annum from an admittedly low base of about 1% of total EU plastics. Global tonnage for 2008 would be around 260,000 tonnes of which 160,000 tonnes were produced in the EU, and these numbers were expected to reach 1 million tonnes globally in 2010, 360,000 tonnes of this being EU production. New investments in German bioplastics announced in 2008 amounted to €200m, including BASF Ludwigshafen’s expansion to 70ktpa and the new 60kt PLA investment in Brandenberg.
Producers are so far mainly small and medium sized enterprises making niche products, and these are improving employment in rural areas as well as making a positive contribution to climate change. Germany has been funding the development and from Jan 2009 the new Packaging Ordinance would give it a further boost by exempting bioplastics from the “take back” rule which mandates packaging producers to take back their packaging after use, for recycling. The cut off for this exemption will be >75% renewable content, measured by C14 analysis to detect the fossil carbon content of the bioplastic.

BASF Persective on Bioplastics

Dr Michael Stumpp, a Group Vice President of BASF (Germany) defined bioplastics to include biodegradable polymers whether based on fossil or renewable sources and polymers based on renewable resources whether biodegradable or not. He argued that there are no inherent ecological disadvantages from using fossil resources: impacts on the environment have to be considered on a case by case basis using life-cycle analysis. If renewables are to become a viable alternative to fossil reserves they must be available at competitive prices on an industrial scale, whilst using arable land efficiently and without compromising food availability or depleting natural wealth. He quoted a UK newspaper article from April 2008 to illustrate the way careless use of bioplastics can cause a backlash:
· Replacing oil-based plastics with bio-based plastics is causing environmental problems
· Bioplastics can increase greenhouse gas emissions, especially methane, from landfill.
· Bioplastics are contributing to a global food crisis
· PLA does not biodegrade in landfill
· UK recyclers do not want their plastics contaminated with bioplastics.
BASF’s bioplastic, Ecoflex® is based on a copolyester of TPA, Adipic acid and 1,4 butanediol, and has been optimised for 100% biodegradation, mechanical properties and easy processing on existing polyolefin kit. It contains no toxic materials and causes no build up of environmentally undesirable materials on biodegradation. Its main uses are in compounds with starch, cellulose or PLA and it is the market standard for organic waste bags, mulch films, plastic carrier bags, flexible packaging and hygiene films. Their eco-efficiency is proved by the Seebalance® method which combines cradle to grave LCA with cost analyses, and with social aspects.
BASF’s Ultramid® bioplastic is a nylon 6.10 polymer using >60% renewable carbon from sebacic acid.

The Case for Renewability

Armand Klein, the EU Business Director Applied Bio-sciences for Dupont (Poland) introduced their “Applied Biosciences” new technology platform which has the target of doubling Dupont’s revenue from non-depleatable resources by 2015, and introducing 1000 new “safety products or services”. Their Renewably Sourced™ initiative provides products with at least 20% renewable content by weight, verified by carbon dating, and backed up by publically available environmental impact data. These products are guaranteed to meet or exceed the critical performance requirements of their 100% petroleum-derived counterparts.
Dupont’s JV with Tate and Lyle to produce 45,000 tpa of bio-propane diol is the basis of the Sorona® and Cerenol™ biopolymers made from 1,3 propane diol and dimethyl terephthalate. The process uses 40% less energy and emits 56% less GHG’s than the petroleum-based PDO process. Compared with Nylon 6, the Sorona® polymer is 37% renewable, emits 63% fewer GHG’s, and requires 21% less water.
Mr Klein observed that they saw no shortage of arable land availability in the EU for bioplastic precursors. Current bioplastics used 0.05% of current agricultural land. There was much unused land in the West, massive potential for yield improvements in the East, and future biotechnology could increase yields much further. Furthermore there was a clear link between the rise and fall of oil-price and corn-price for 2008, destroying the argument that increasing use of corn in bioplastics was increasing the corn price.
He pointed out that our use of global resources had been in balance with nature’s ability to supply in 1985, and so the concept of Earth Overshoot day was born in that year with a Dec 31st date. This year Earth Overshoot day fell on September 23rd, and for the rest of the year resources from future years were being consumed. Clearly this could not continue for long.

Bioplastics Future?

Filippo Velli, Packaging Deputy Director of Ferrero (Italy) noted the increasing rules and regulations which drove manufacturers towards renewable materials:
· The July 2008 “sustainable consumption and production plan” from the EU established rules for sustainable production and consumption.
· The French Ministry of the Environment agreement with the Retailers Association to promote 300 green products for mass consumption by giving them the best shelf space.
· The Dutch tax (from January) on the manufacturers and importers of packaging materials – with rebates for bioplastics.
· The German packaging act which requires manufacturers to deal with the recycling or disposal of any packaging sold.
· The UK specification (PAS 2050) for the assessment of lifetime GHG emissions for goods and services.
Trade initiatives were also appearing: Tesco was giving Clubcard points for reuse of carrier bags, including those from competitors. Wal-Mart was dictating sustainability standards for suppliers.

PLA Bottles

Marc Verbruggen of NatureWorks gave Alberto Bertone’s paper on the Sant Anna BioBottle launch. The 0.5 and 1.5l still water bottles will be sold at a premium in a complete line of eco-products, first in Italy. The shrink-on labels are also made from PLA. They claim to be recyclable and compostable “if your local authority uses industrial composters – you should check”

PLA Phones

Frederico Giuliano of My Italian Design and Emma Clerici of Baolab have developed a new cordless phone case for Telephone Italia. They tested Cereplast, Ingeo, Kareline and Mater-Bi for sustainability, injection-mouldability, identity, availability and cost and chose Ingeo because it worked, was made from corn and had “the most options for not using landfill”

Bioplastics in Japan

Isao Inomata, an Adviser to the Japanese Bioplastics Association reminded us that CO2 concentration in the atmosphere was increasing at 1.5ppm per annum. Put in another rather more memorable way, while the Earth’s natural processes could add and remove 11 billion tonnes per year of atmospheric CO2, human activities were now adding an additional 12 billion tonnes per year. To help mitigate this, Japan has a strategy to replace 2.5 million tonnes of non-renewable plastics with renewables to achieve a “20% renewables” target by 2020. It is also targeting the reduction of crude oil use by 11 million kilolitres per year from 2010.
Bioplastics (defined here as biodegradable and/or biomass-derived thermoplastics) were chemically synthesised, produced by microbes or existed in nature.
Chemically Synthesised products included PLA and copolymers, polycaprolactone and copolymers (e.g. Tone from Dow), PBT and copolymers (e.g. Ecoflex from BASF), and polybutyrenesuccinate and copolymers (e.g Biomax from Dupont). PLA capacity was 150,000 tonnes, Biomax 90,000 tonnes, and Ecoflex 14,000 tonnes, presumably not just in Japan.
Microbial products were mainly based on polyhydroxybutyrates and copolymers with hexanoates and valerates. Mirel from Telles was listed as the largest of these with a capacity of 50,000 tonnes per annum.
Natural products were listed as cellulose acetate, esterified starches and starch/GreenPla compounds (e.g MaterBi from Novamont)

Certifying Bioplastics

Joeran Reske of the EU Bioplastics Association defined bioplastics as compostable materials according to the relevant standards and/or made at least in part from renewable raw materials.
Compostability testing would take around 7 months with each raw material used being tested according to EN 13432, EN 14995, ASTM D-6400 or ISO 17088. The contents of the used product would also have to prove compostable by the same methods. Then National Certification Bodies would have to be approached to use the compostable logo in labelling, and this would take 3-6weeks. Costs would fall mainly to the manufacturer of the raw materials, but the cost of acquiring the logo would fall to the product maker.
Renewability testing would involve C14 assessment of the product according to ASTM D-6866 but CEN would be looking to see if this method was appropriate in the EU. This would give a “% biobased” result which could be used in labelling.
Environmental Performance would also be important and here LCA methods would be used.
Labelling, especially the choice between a single “% biobased” label or a multiplicity of green labels such as C footprint, Recyclable, Compostable, and Low Energy remained to be decided after discussion between all interested parties.

Dutch Bioplastic Legislation

Patrick Gerritsen of Natura Packaging reviewed the new packaging “producer responsibility” law and tax introduced in Jan 2008 and intended to reduce packaging and shift to those types with reduced impact. The new tax only applies to companies placing more than 15 tonnes/year of packaging onto the market each year and is a combined carbon tax, litter tax and waste separation tax. The tax rate is calculated based on the “greeness” of the product, effectively the total greenhouse gas emissions from the whole lifecycle of the packaging in question.
Bioplastics, defined according to EN 13432 have been added as a tax category, the others being paper/paperboard, glass, steel, aluminium, wood, plastic and others. After glass at 0.0622€/kg, bioplastics and wood are in the next lowest tax band for 2009 (0.0733€/kg) while petro-based plastics (0.4339€/kg) and aluminium (0.8766€/kg) attract the highest levels.
The results after nearly a year? Bioplastics are now found on organic products in 75% of the supermarkets in Holland, and are used on a much larger scale in agriculture. PLA drinking cups are increasingly used at big events and concerts, and most local authorities now accept bioplastics in “green bin” – usually garden – waste. There is now a lobby for bioplastics to be tax-free because even without tax they will cost more.

Mater-Bi Polymer Applications

Stefano Facco, New Business Development Manager for Novamont (Italy) reviewed the growing list of uses for their starch-based bioplastic following their doubling of capacity (to 75,000 tpy) in 2007.
· Compostable table-wear in fast food chains and canteens allowed everything left on the tray after a meal to go into the compostable bag. (no separation required).
· Agricultural mulch films can now be laid automatically as crops are sown and can be left in the ground where they disappear before the next season.
· Food and garden waste bags are compostable.
· Biodegradable shopping bags are in demand by supermarkets.
· Hygiene products use Mater-Bi film for backsheet and perforated topsheet and for their primary and secondary packaging.
· Co-extruded films, extrusion coating and extrusion laminating is now under development for food packaging and rigid packaging.

Land Availability

Michael Carus, MD of the Nova Institute (Germany) led a discussion session debating whether or not the arable acreage would be available to meet the needs of bioplastics growth between 2006 and 2020. The facts he presented were as follows:
· 3.3 billion hectares of rain-fed arable land were available on Earth now. Of this, 1.5 billion were already farmed, 0.8 bn were “potential forest land”, 0.33bn were protected in National Parks etc, and 0.1bn were committed to residential areas and their transportation links.
· This left 0.57 billion hectares of unused agricultural land.
· Applying the growth in demand for land needed to sustain the population increase to 2020, including their growing interest in meat and dairy products, and their need for bioethanol meant that 0.22 billion hectares of this unused land would be used by 2020.
· So, 0.35 billion hectares of arable land would be available to support a growing biomaterials industry without any need for irrigation.
· In short, there would be no shortage of available land.
· The switch from wheat to meat which occurs with increasing wealth is the big consumer of unused land.
Western Europe’s consumption of bioplastics in 2007 has been estimated by the Nova Institute at 60-70,000 tonnes. Of these, thermoplastic starch is 40%, extruded starch, 20%, PLA is 15-20% and Cellulose Acetate is 15%. The rest, including PHAs accounts for the remaining 5-10%.
Other points from the discussions:
· The move to a sustainable bio-based economy from the oil-based economy of the last 50 years is essential and is starting now, even though plenty of oil remains.
· Oil and gas will continue to be used, but the need to mitigate or offset the carbon release will make its use increasingly expensive.
· Bio-refineries were theoretical just a few years ago. Now they are going into production.
· Bioethanol could be produced from 15% of agricultural land without any effect on food prices. At present only 1% of the EU crop goes to biofuels (unlike the USA where the figure is nearly 30%)
· Recent food-price rises were due to low stock levels.
· Last year’s EU harvest was the 2nd best ever, and this with 10% (8 million hectares) being set aside. This set-aside land will now go back into production.
· Bioethanol yield per hectare can be increased dramatically if the crops are regarded as non-food. However farmers resist making commitments to crops on a multi-year basis, preferring to plant whatever appears capable of yielding the most profit. (“If you want multi-year commitments talk to the foresters”.)
· The use of wood as an energy source should be prohibited. Energy generation is an end-of-life option and wood can cascade through several products before it would need to be disposed of in energy generation.
· Brazil can switch easily from bioethanol to sugar production and back again depending on economics. At present the split is 50/50.
· However bioethanol only makes sense now because of massive government subsidies. It will disappear as other renewable energy sources grow.
· Bioethanol can be converted to ethylene and propylene and hence to renewable versions of polyethylene and polypropylene.
· Bioplastic Association members estimate a hectare of land can yield 2-3 tonnes of bioplastic, so the current world output of bioplastics is equivalent to only 100,000 hectares.
· Maybe farmers should concentrate on food production leaving specialist biomaterials producers to develop agriculture for biomaterials.
There seemed to be reluctance on the part of the farmers present to regard wood and cellulose as an important source of biomaterials, maybe because it did not need farmable arable land. Even the Bioplastics Association appeared biased towards bioplastics made from agricultural crops and do not include cellulose acetate in their statistics. CRW

New PLA Plant for Germany

Bernd Merzenich of Pyramid Bioplastics (Germany) introduced the topic by showing artists impressions of the new PLA plant now being built next to the old Trevira polyester plant. By 2010 the pilot-plant would be producing 500 tpa of polymer for test marketing and process development. By 2012 the first of the 3 planned 60,000 tpa units would be operational.
Uhde Inventa-Fischer had developed the technology and this used proprietary new approach to the lactide formation step. They would be managing the construction, and Dr Rainer Hagen, their VP R&D took over the story. Lactic acid would arrive at the site by rail. It would be converted to a prepolymer by polycondensation and then depolymerised to lactides. The lactides would be purified and undergo ring-opening polymerisation to PLA. The prepolymerisation step was essentially standard polyester technology, and the final lactide polymerisation was polyamide technology. The cyclising depolymerisation step to lactide was new technology.
1 tonne of PLA would require 1.3 tonnes of lactic acid, and this would require 2.3 tonnes of corn with a 72% starch content. In fact any crop containing starch or sucrose could be used to make the lactic acid, but the lactic acid has to be high quality “polymer grade” material.
PLA properties were controlled in polymerisation:
· A quick crystallisation led to low (<2%)>170oC.
· Slow crystallisation led to moderate (4-8%) mesolactide levels, molecular weights around 100,000, and a melting point in the 140 to 160oC range.
· Amorphous PLA had a high (>12%) mesolactide level, molecular weights in the 35,000 to 70,000 range and no melting point.
The market potential for PLA had been estimated at 700,000 tonnes per year, this being 5% of the total use of plastics in packaging the EU. This PLA would need 910,000 tonnes of polymer grade lactic acid, a number to be compared with the world LA capacity of 512,000 tonnes in 2005 and world LA consumption of 303,000 tonnes in the same year. Of this 146,000 tonnes were used in industry, the rest being used in food and a little in pharmaceuticals.
The costs of lactic acid for the new plant were estimated at 700 to 900 €/tonne depending on source and location when produced at the rate of 50,000 tonnes/year. Conversion to PLA in a 60,000 tonne unit would cost up to 400 €/t, 76% of this being capital-related.
Asked where the lactic acid for the new plant would be made, Mr Merzenich said it was a secret. Would it be made from corn? That was a secret too.

Compounding Bioplastics

Dr Christian Bonten, Director of Technology and Marketing for FKUR (Germany) claimed that raw bioplastics like PLA can hardly be processed on conventional film and moulding equipment and the key to their conversion lay with the compounder. PLA suffered from brittleness, low softening temperature and a limited hydrolysis resistance and these could be mitigated in compounding.
FKUR has developed extruder screw designs to suit these polymers and can now compound them with fillers or blend nominally incompatible bioplastics such as PLA and PHA together. They add modifiers such as dispersing agents to stabilise phases, and carry out proprietary reactive blending with coupling agents and compatibilisers to connect the phases together. Transesterification is used to improve phase compatibility, and they also carry out chain extension of the more easily blendable oligomers by reactions which take place in the last third of the extruder.
Their Bioflex® series of PLA compounds has been optimised for standard blown or cast film lines and these incorporate natural fillers, additives and other plastics from renewable resources. The S Series of Bioflex® has improved oxygen barrier properties while the A series has excellent transparency and mechanical properties similar to PP. The F 1130 variety was for diaper backsheets.
Biograde® used cellulose acetate compounded with starch for injection mouldings, thermoforming and blow moulding. Biodegradable bottles and caps with polystyrene-like stiffness were illustrated.
Fibrolon® was a wood/plastic composite with very high toughness and stiffness. The F range used bioplastics in the blend to achieve 100% renewable status.

Hitachi’s PLA Process Improvements

Dr Toshiaki Matsuo, a senior researcher with Hitachi (Japan) described how their PLA process developments were overcoming the twin problems of conventional PLA production, racemisation during thermal cracking and yellowing during polymerisation.
· Hitachi’s Kontro thin-film centrifugal evaporator has been shown to achieve lower levels of racemisation during thermal cracking of the oligomer to lactide. Lower levels of meso-lactide result.
· Their solution to yellowing has been to develop a pilot-scale 2-reactor system avoiding the need to run the polymerisation at the high temperatures where thermal degradation occurs. In the conventional process the single reactor heats the lactide to about 230oC to get ~100% conversion to polymer. In the new process, the first reactor runs at 150-170oC until the polymerisation plateaus at about 60% conversion (~5 hours). The mixture is then transferred to the second higher temperature reactor (~200oC) for a further 5 hours to get the conversion up to ~100%.

PURAC Lactides

Hans van der Pol, Marketing Manager of PURAC (USA) whose core technologies are fermentation and purification and whose core products are lactic acid and derivatives said their technology was used at Blair, Nebraska and in the new 100,000 tonne/year Thai lactic acid plant. The Thai development was a €100m project, and the total capital for a finished PLA plant (built by a PURAC partner?) in an integrated complex would be twice that.
D-lactic acid has now been produced in Spain and a D- and L-lactide demonstration plant with a 3000-5000 tpa capacity started up in August this year.
PURAC were forecasting a global market for PLA of between 250 and 500Ktons/a by 2015 depending on the assumptions made. The high figure assumed the development of appropriate plastics technology, the development of high added value products and a much wider range of applications. The lower, base case, assumed the opposite, with today’s narrow range of low-value applications predominating.
They are now looking for partnerships with “technology companies and plastics producers” to further develop their concept of higher value PLA plastics from their lactides with relatively low investment and lead-times.
One example of a success in this aspiration is the recently announced partnership with Sulzer and Synbra (ex Shell) to produce PLA foam – Biofoam® - from PURAC’s Puralact™ lactide, a high quality, bio-based, GMO-free product made using PURAC’s continuous polymerisation with simultaneous devolatisation.

Dow Bio-materials Strategy

Dr Dieter Herzog, Global Portfolio Leader, Ventures and Business Development for Dow Chemicals reviewed their logic for wanting to become big in bio-based chemicals. In short, they are big in agrichemicals and germplasm and so a move to bio-based appears natural. Furthermore Wal-Mart is encouraging it and green products seemed to get better margins. There are 3 main areas of risk with this strategy:
· Security of agricultural materials supply
· The technical feasibility of converting biomass on a large scale at low cost
· The acceptability of the resulting products as substitutes for fossil-based materials.
Today, they are gaining access to the feedstocks and launching new bio-products in their established markets. For the 2010-15 period they would expand biotechnology based on “thermo-chemical competencies for new materials” (?). After 2015 they would “implement novel crop and plant-made materials for future customer needs.”
Key feedstocks would be lignocellulosics, fats, oils, sugar and starch. In 2007 they announced their JV with Crystalsev to make polyethylene from sugar; their Renuva™ bio-based polyols which used up to 60% less fossil-fuel by blending seed-oils with polyether monomers, and their new epichlorohydrin plant being built in China to process biodiesel. Together these developments could make Dow Chemicals the biggest bio-mass converter in the world but at present they are simply prospecting for new business, while “making outside bets in selected spaces, leveraging market-pull to provide development focus, syndicating to mitigate risk while planning to fail-fast but leverage learning”. In response to questions Dr Herzog said Dow was not being pro-active, they were simply getting into a position where they could react to demands for more bioplastics should they arise.

Kaneka’s Biopolymers

Yasuhiro Miki, PHBH Market Development Manager of the Kaneka Corporation (Japan) updated progress on his project. Poly 3-hydroxybutyrate 3-hexanoate copolymers were made by micro-organisms when fed on plant oils. They melted at 100-160oC, were soft like PE and PP, heat resistant and very biodegradable both anaerobically and aerobically, while being stable to hydrolysis over 5 weeks at 60oC and 50% RH. Haze values had proved impossible to improve due to the semi-crystalline nature of the polymers.
Foamed PHBH showed similar resistance to repeated static compression stress, similar heat stability and similar heat shrinkage when compared with foamed PP. They made two copolymers, one with 7 mol% of 3-hydroxyhexanoate and the other with 11 mol%, and it was the lower 3-HH variety that gave the lower heat shrinkage.
Several tons had now been produced for market development trials and they were looking for development partners.

The Succinium™ Project

Franck Thumerel of Roquette Freres (France) and Richard Jannssen of DSM (Holland) described their joint venture in the Biohub® petrochemical replacement programme, one of the objectives being the production of bio-based succinic acid as a chemical intermediate. Biohub® is a 6-year programme costing €90million. It is expected to generate €700m of industrial investment starting in 2010, requiring 1.3 million tonnes of corn, the equivalent of 150,000 ha of arable land. The main drivers are:
· Climate change and the need for lower C-footprint products.
· Cost reduction as oil price increased.
· Demand for bio-based packaging from retailers.
· Legislation favouring renewable over fossil materials.
· DSM’s focus on Life Sciences and Performance Materials.
· Roquette’s focus on integrated bio-refineries and vegetal chemistry.
· CO2 is a feedstock for bio-succinic acid.
Since getting together with Roquette in Jan 2008, DSM has obtained a grant from the US Department of Energy for enzyme development for use in cellulose-based biorefineries, invested in Tianjin Green Bioscience to produce polyhydroxyalkanoates, and has acquired the Polymer Technology Group, a leader in biomaterials for medical applications. Roquette’s biorefinery in France processes 3,800 tonnes/day of wheat or corn into starch, sweeteners and polyols. They see starch as capable of yielding monomers and polymers capable of replacing those based on naphtha.
One of the new bio-based polymers now emerging is polybutylene succinate, and this is being put into production by Mitsubishi, the planned capacity being 10,000 tpa in 2010 and 100,000 tpa in 2015. Developments involve compounding the polymer with other fibres e.g. bamboo, developing co-polymers, and blending it with starches, PLA or PHA. In addition to the expected applications in agricultural mulch films, compost bags and food packaging, PBS can be processed into fibres and nonwovens.
Other possibilities include polyisosorbide succinate made by hydrogenation of glucose to sorbitol and dehydrating this to isosorbide for polymerising with succinic acid; and 1,4 butane diol, a precursor for bio-based polyesters and polyurethanes.

Genetics to Bioplastics

David Pearson, Marketing Director of Limagrain Cereal Ingredients (France) said Limagrain had a €1.2billion turnover and was the 4th largest seed producer in the world. It had a €160m R&D budget for 73 R&D labs around the world, a unique achievement for a co-operative of 600 farmers collaborating on plant breeding, seed production and soil improvement for food production. Now they were looking at non-food products and had in 2006 launched Biolice®, said to be Europe’s first biodegradable plastic made from cereal flour rather than starch.
10,000 tonnes/year of Biolice are now produced for films and shopping bags, refuse bags and thermoformed food containers. While it did not emerge during the talk or questions, Mr Pearson revealed privately that Biolice® was simply BASF’s Ecoflex fossil-based polymer filled with 40-50% of cereal flour, adding that BASF have a complete monopoly on biopolymers for blending with starch or flour.

Green Polymers from Succinic Acid

Patrick Piot, General Manager of Bioamber (France) described the company as a 50/50 JV between DNP (Diversified Natural Products – a New-York based “Green Chemistry” company) and ARD, the R&D centre of a group of French agribusinesses. DNP has worldwide exclusive rights to US DoE patents for the production of succinic acid from glucose using an E.coli mutant. Bioamber has pioneered the development of the first commercially viable technology package for producing bio-based succinic acid using the DNP rights. In essence, the E. Coli feeds on the C5 glucose from starch and adds CO2 to make succinic acid. The SA is purer (>99%) than that achieved from petrochemical sources, and can serve as a platform molecule for a range of polymers and other monomers which will be independent of oil-price volatility.
In 2007 they built an 80 m3 fermenter/reactor for the process and demonstrated it worked well. Construction of a 2000 tpa succinic acid plant (€21m invested) is now underway and is due to be commissioned in 2009. Their business model includes licencing out the process and providing turnkey plants from 2010. Bio-based 1,4 butane diol will soon be available.

Cellulose Diacetate Films

Martyn Hanney, Sales Development Manager of Clarifoil (UK), a company once part of the Courtaulds Group and a user of acetate flake made primarily for cigarette tow production at Spondon in Derby, is relaunching acetate – produced on the site since 1949 - as a sustainable bio-based biodegradable packaging film. Made from woodpulp and acetic acid, the diacetate dissolves in acetone and can be cast into films, spun into fibres or moulded into rigid solids. The films, made down to 14 micron, have near-perfect transparency, with a high gloss, low haze and near-zero birefringence. They are certified biodegradable to EN 13432 and ASTM D6400.
· Wal-mart has now switched from OPP to cellulose acetate for carton windows in fresh food packs.
· CA is naturally breathable so does not mist up when covering moist food.
· OPP is being replaced by CA for print media lamination particularly among retailers who claim to be green.
· CA is displacing cheaper OPP alternatives in the pressure sensitive tape market.
· UV absorbers can be added to CA to extend shelf lives
· A low tear strength is marketed as conferring tamper-evident properties to labels and cap sealers.
The major new interest in acetate as a bio-plastic began about 12-18 months ago, and Mr Hanney predicted continuing growth as new applications and customers are coming on stream faster than ever before.

Biopolymers at DuPont

Karlheinz Hausmann, a Senior Research Associate at Dupont Packaging and Industrial Polymers (Europe) reviewed their activities:
· Biomax® is a thermal modifier developed to make PLA more temperature resistant and more durable by reducing brittleness. It acts as a processing aid in casting, blow moulding and thermoforming while maintaining good clarity and food contact compliance.
· Bio-PDO™ is converted into Sorona® and Cerenol® polymers, the former for textile fibres and films, the latter for stretch fibres and elastomerics.
· Biomax® PTT 1100 is for cosmetic packaging film, and the Bio-PDO content makes it about one-third renewably sourced. It’s like polyester but more flexible.
· Biomax® TPS is a range of high amylose thermoplastic starch for sheets, mouldings and packaging capable of giving 80-95% renewability while degrading completely on contact with moisture. Flushable products were claimed as an application, and a tampon applicator was specifically mentioned.
· Zytel® RS is a renewably sourced polyamide made using sebacic acid derived from the castor plant. If polymerised with diaminodecane, the resulting nylon 10,10 has 100% renewable carbon, but if hexamethylene diamine is used, the resulting nylon 6,10 is 62% renewable.
· Nylon 6,12 can be made with 66% renewable carbon if dodecanedioic acid from palm oil is polymerised with hexamethylene diamine.
Calvin Woodings

Thursday 23 October 2008

EDANA Filtrex 08: Cologne : 6-8th October 2008

Key Points• Fresh and waste water filtration is now the largest and fastest growing segment of the filter media market.
• The growing demand for cleaner water is attracting major new players into the water treatment market.
• H&V's Nanowave™ technology yields a filter with a wavy surface which provides half the pressure drop of the equivalent glass filter with 3 times the dust holding capacity and a higher filtration efficiency when discharged.
• Irema Filter is co-forming PP nanofibres with a standard PP meltblown to give a gradient structure which has higher capacity, lower pressure drop and longer charge retention than the usual two-layer structure.
• CamilFarr use a new form of active carbon with “Rapid Adsorption Dynamics” in an F7 filter to absorb low concentrations of pollutants quickly.
• Norafin's 420 gsm hydroentangled fabrics with a split bico microfiber surface can match the performance of a 500 gsm needlefelt with an ePTFE membrane surface.
• Europlasma use plasma to polymerise a monomer onto PP to render it permanently hydrophilic. The monomers used are secret and the process needs a vacuum.
• With air handling fans consuming 15% of all electricity consumption, the EU are expected to require energy efficiency labelling of air filters in about 3 years.
• The nanoalumina whiskers used in Ahlstrom's Dispruptor™ papers can immobilize 8 micron active carbon powder without the need for binders which can reduce efficiency. The resulting filters are excellent for cleaning up water for drinking.
• Dupont's HMT nonwoven uses direct-spun continuous nanofibers to achieve membrane-like filtration at lower pressure drop.

Keynote: Filter Media Markets

Ken Sutherland of Northdoe UK defined the filtration market to include deep-bed sand filtration, coarse porous materials, wound yarns, woven fabrics, felts, papers and nonwovens including glass and carbon materials, sintered metal and ceramic media and polymeric membranes. Strictly speaking membranes were not filters because they separated molecules by rate of diffusion, and were not intended simply to remove particulates.

His $ values were at the point of sale to the filter equipment maker or replacement user and included all industrial, commercial and residential filters, whether fitted as original equipment or sold as replacements. Data of most interest to the nonwovens industry – tonnes or square metres of roll-goods - was not available:

• The world market for filter media in 2007 was $21.7 billion.
• 38% of this was sold with the filter hardware, and 62% in the aftermarket.
• Nonwovens accounted for 27% of this and Paper (surprisingly) another 2.9%.
• Membranes were the biggest sector (35.5%) with spunmelt nonwovens (14.3%), metallics (10.4%), felts (9.9%) and constructed cartridges, i.e. filter media plus frame and end caps as in most automotive air and oil filters, at 7.1%, making up the top-five filter types.
• USA (24.4%), China (12.1%) and Japan (7.5%) were the main countries of use. China was growing much faster than the others and because of the difficulty of getting good information could already be much larger than this. (The USA had fallen from 50% a few years ago.)
• Fresh and waste water filtration (14.3%) is the largest individual sector, followed by Bulk Chemicals and Petrochemicals (13.6%), Fine Chemicals and Pharmaceuticals (9.6%), Food & Beverage (8.3%), Power Generation (7.4%), Medical and Health (6.3%) and Mining and Metals Processing (6.0%)
• The global market was growing at 5.6% annually, China at 10.1%. Water treatment was growing at 6.8%.
• Major growth drivers were:
• End user demands for cleaner and purer water and air. (“Everyone, all the major companies, are getting into water treatment”)
• Environmental regulations tightening
• Growth in China and India and other developing regions.
• “Most of the areas the World now needs to improve involve using better filtration.”

Technologically, the development of ever finer fibres, and materials with better heat/chemical resistance was leading to innovative new filters. Heat/chemical resistance was getting more important as companies tried to save energy by extracting heat from effluent: the heat exchangers now requiring pre-filters to keep them working properly.

Asked for more detail about the $ values, Mr Sutherland said the total filtration market (equipment plus media) was $44bn, and all his numbers were based on the exchange rate on July 1 st 2007.


Andre Boni, Director of Marketing for Hollingsworth and Vose described their proprietary new technology to make an “extended surface synthetic media”. Nanowave™ was a development of Nanomelt™ introduced at Index in 2005, the latter having had problems due to its higher initial pressure drop, lower test dust capacity and premature blinding by fine dusts.

The unique feature of Nanowave™ was its wavy surface, and this gave the following benefits:
• Double the alpha value of conventional discharged melt-blown media (alpha=Efficiency/Pressure drop)
• Double to treble the dust holding capacity (wavy surface, like crepeing, gives twice the surface area per square metre of filter.)
• The nanofibres give a high discharged efficiency.
• The structure can also be charged for even higher efficiencies
• Wave height, density and polymer type, as well as fibre dimensions can be adjusted for specific applications.
• It is stiffer and more resistant to compression.

Initial focus is on an HVAC bag filter to meet the F5 to F9 classes of EN779. Here synthetics, usually charged and so liable to lose efficiency over time, are battling with glass fibre which is more consistent but might shed fibres. Nanowave™ gives half the pressure drop of the equivalent glass filter, with 3 times the dust holding capacity and a higher efficiency even when discharged.

Asked about price, Mr Boni said it would be a premium product, but H&V would position it competitively. It is not commercial but test quantities can be made available.

Integrating Nanofibres

Wolfgang Rupertseder, Plant Manager, Irema Filter ( Germany ) reminded us that diffusion is the main mechanism for fine particle capture, and then the particle must stick to the fibre. The force of adhesion is highest when the fibre diameter equals the particle size, and in a real world gradient filter you can see that the coarse fibres catch the big particles and the fine fibres catch the small ones. Once fibres get smaller than about half a micron, a “slip-flow effect” (the air velocity at the surface is no longer zero) occurs and this reduces the pressure drop to about 70% of that calculated using theory which works for larger fibres.

Rather than create a layered structure with nanofibres laid on top of coarser melt-blown fibres, Irema co-mingle the fibres by spraying the two types into one another before they land on the conveyor. A bulky gradient structure is obtained with the top surface being richer in nanofibres than the bottom. For some applications a third head will apply a protective microfiber layer to the top side. The heads look like conventional melt-blow heads, and the nanofibre size (0.1 to 0.5 micron claimed) is probably obtained by running the nanofibre head at very low productivity, and the whole line at low speed.

The product is commercial in automotive cabin air filters where it gives a 70% NaCl capture efficiency and longer filter life. Media for HEPA filters is under development.

Results shown were for charged media, but in response to questions Mr Rupertseder said the blend structure discharges more slowly than a layered structure. PP is the main polymer used but the process has been shown to work with PET.

Nanogate Technology

Yvonne Klattwitter, Product Manager for Nanogate ( Germany ) said their core competence was formulating products using nanomaterials and processes based on nanotechnology. Their N-Charge® coating had been designed to improve the ability of surfaces to store an electric charge and works as a dielectric which prevents discharging due to particle capture. Realising that this may have applications on fibres and fabrics, they developed Permastatic® as a spray-on or paddable water-based coating.

Nonwovens coated with Permastatic® have:
• The same permeability as untreated nonwovens. The coat is 100nm thick.
• Increased fractional filtration efficiency. Retention of submicron particles improves from 70% to 90% in vacuum cleaner bags as tested by Filz Fabric Fulda.
• Longer lasting electrostatic properties. Charge retention was up from 61% to 83% in a 5 months test. In a 2 year test 100% PP and 100% PET retained their initial charge of 3-4kV almost unchanged. (Were these fibres or films?)
• Resistance to water washing and IPA extraction

Permastatic® can be combined with other treatments to give improved cleanability, hydrophobicity or hydrophilicity, and is said to be easily incorporated into existing processes as a low-cost upgrade. Ms Klattwitter could not answer questions about cost.


Thore Bertilsson and Jörg Scharnberg of CamilFarr ( Sweden ) defined air pollution as “matter found in the atmosphere not belonging to its natural consistency, or matter found in indoor air with harmful effects on people and materials”. Examples included dust, soot, mist, fog, gases and vapours and radioactivity. They can be natural (forest fires, volcanos, dust storms) or man-made (incineration, fossil fuel combustion, factory effluent). Very small particles and gases presented particular problems. Normally polluted town air had a bimodal distribution with particle size peaks at around 0.2 and 8 microns. Modern diesel engine exhausts emitted particles below 0.3 microns and these could pass through the lungs into the bloodstream. However an F7 air filter with >50% discharged efficiency at 0.4 micron would give acceptable air quality, reducing PM10s by 87% and sub PM1s by 75%. To improve on this and get noticeably better air quality a filter meeting EN13779:2007 would be required.

Atmospheric polluting gases - NOX, SOX, NH3, HCl, VOCs – and indoor pollutants, formaldehyde from wood and carpets, ozone from photocopiers and various unpleasant odours from food and waste can only be removed by adsorbtion on active carbon, active alumina or ion exchange resins. Existing granular forms of active carbon are too slow to adsorb low concentrations to be useful in HVAC systems but an new form with Rapid Adsorption Dynamics is now available. RAD deals with really low concentrations of pollutant quickly by virtue of being a really small particle of active carbon, and it can be integrated into an F7 particle filter.

Other pollutants which are currently untreatable include CO 2 , CO, CH 4 , NO, He and Ra.

Ahlstrom Disruptor™ in Reverse Osmosis

Domingo Sanchez (R&D) of Ahlstrom Filtration (USA) replaced Rodney Komlenic, VP Business Development, to deliver the paper on the Dispruptor™ fabrics made under licence from the Argonide Corporation. Here, naturally occurring 2nm by 250nm boehmite whiskers are attached to submicron microglass fibres which can then be easily processed by Ahlstrom into wet-laid nonwovens. These nonwovens have a 2 micron average pore size and a 42,000 m 2 nanofibre surface area per square metre of nonwoven. At pH 7.2 they have a >50millivolt zeta potential which is effective for up to a micron from the whisker surface, this allowing them to capture particles below 0.5 micron electrostatically, while the large particles are retained mechanically. In some tests they have been shown to retain 6 times their own weight of contaminant. They can be used at operating temperatures above 400 o F, yet have filtration efficiencies similar to the UF/MF polymer membranes while incurring a fraction of their pressure drop. Examples of use covered products normally associated with reverse osmosis, nanofiltration, ultrafiltration and microfiltration:

• Compared with membranes having a range of pore sizes (0.025 to 1.2 microns) Disruptor™ media removed B. diminutia, MS2 virus, and an endotoxin with higher efficiency at lower pressure drop and higher flow rates.
• T4 phage was adsorbed from a concentrated solution by simply immersing Disruptor™ in the solution.
• Iron, tin, lead and copper particles, problematic in drinking water and waste from metal finishing, were all removed easily by Disruptor™. Dissolved iron was also removed.
• The nanoalumina whiskers will immobilise 8 micron powdered active carbon (PAC) powder without the need for binders which can reduce the PAC adsorption efficiency.
• The resulting Disruptor™PAC paper can remove 1gm of chlorine or iodine from water per gram of PAC.
• Disruptor™PAC successfully removed all the humic acid from drinking water spiked with 20 FTU and reduced the turbidity of the water to zero. Even standard Disruptor™ removed more of the humic acid than the tightest (0.22 micron) Millipore membrane.
• Disruptor™ remove trace amounts of organic matter from lake water at high flow rates and very low pressure drop.
• They effectively reduce water contaminants missed by GAC beds, flocculation, microfiltration and ultrafiltration processes.
• As prefilters on reverse osmosis processes, the membrane cleaning routines can be increased from monthly to six-monthly due to their ability to reduce the silt density index (SDI).
• Biofouling of membranes by proteins, lipids, carbohydrates and amino acids can be significantly reduced.

Disruptor™ nanoalumina whiskers have been used in medicine since 1926 and have FDA approval for use in human vaccines. They have now passed the NSF/ANSI standard 42 for water contact use and standard 53 for water contact and cyst reduction, USP class VI and endotoxin testing. In conclusion Ahlstrom believe this is a real breakthrough in reducing a wide range of reverse osmosis biofoulants via electroadhesion and mechanical entrapment.

Asked about the cost of the papers, Mr Sanchez simply said $20/m 2 for an average basis weight.

Microglass and Spunbond

Dr Werner Groh of Johns Manville ( Germany ) introduced their new CombiFil® Premium air filter medium made by flame-blowing 1-3 micron glass fibres between two layers of spunbond polyester. The process can be used to make filter efficiencies up to HEPA with high stiffness and pleatablility without the need for wire supports. It holds more dust at lower pressure drops and maintains a stable filtration performance over longer times than the charged synthetic media with which it competes. Specifically, an F8 Combifil®Premium filter holds more dust at a lower pressure drop than an F7 synthetic.

Price? Dr Groh said it would be ~€3/m2 or about twice the cost of a standard material. The microglass was spray bonded with phenolic resin, which also served to bond the polyesters in place.

Spunlaced for Membranes?

Victor Lorentz, Sales Manager of Norafin ( Germany ) described the versatility of their core technology, hydroentanglement, pointing out that it was capable of making filters to compete with needlefelts in all applications. Furthermore it gave filters with a more uniform pore structure over a wider range of basis weights (40-700gsm). For demanding applications, metal or glass scrims were used as reinforcement. A 320 gsm hydroentangled filter gave efficiencies comparable with a 500gsm needlefelt at a much lower pressure drop when the same fibre were used.

If splittable bicomponents were used, much finer filters could be made, but only over an 80-120 gsm range because lighter fabrics were too thin to withstand the splitting pressures, and heavier ones were too costly to split sufficiently. Because the splitting occurred mainly at the surface, a gradient structure with a membrane-like surface was obtained in a one-pass operation without the need for lamination and binders. The fibre splitting increases the filtration efficiency from 65 to 95% for 1 micron particles on 1.3 dtex fibres. If a 100 gsm “microsplit” fabric was laminated to the 320 gsm standard HE fabric the resulting filtration performance had been shown to match a 500 gsm needlefelt with an ePTFE membrane surface.

Asked about the mechanical properties of the spunlace, Mr Lorentz said they were more robust than the equivalent needlefelts and the membrane surface more durable than the ePTFE. Could such materials be used in HVAC? Yes, if the split-fibre layer was laminated to a more bulky base.

Pleatable PET for Depth Filters

Dr Ulrich Hornfleck Sales Director of Sandler AG ( Germany ) observed that carded polyester, chemically bonded in thicknesses up to 3mm can be easily pleated to make an excellent self-supporting coarse dust filter for use in filter classes from G3 to F5 depending on the fibre decitex. However the finest cardable fibre diameter (i.e. about 10 microns) prevented this construction from entering F6 and above.

A new 3-layer structure with a highloft base, an ordinary fine fibre carded polyester centre and a melt-blown polyester surface layer has been shown to maintain its pleatability, offer temperatures of up to 120 o C at constant load with 200 o C peaks, have high mechanical stability and a very high crack resistance. Air permeability and dust holding capacity was superior to F7 microglass media.

A questioner was concerned that the comparisons between microglass and such a thick polyester filter would be invalid, because the use of flat sheet test methods rather than pleated media tests would bias the conclusions in favour of the thicker material. In real filters the glass media would allow a higher pleat density.

Characterisation of Needlefelt Surfaces

Joseph Schuberth of the Vienna University of Technology ( Austria ) has developed a method for comparing the particle penetration and particle holding capacity of filter media. A light microscope and image analysis software was used to determine the surface porosity and the pore depth distribution of a range of felts. Combining these with the mean clean gas concentration and dust loading obtained from a VDI 3926 Type 2 tester, correlations between the optical and physical tests were obtained. These calibration graphs now allow the clean gas concentrations and dust holding capacities of other needelefelts to be estimated simply by using the microscope and image analysis software. The optical measurements can also be used to calculate the relative standard deviation of the pore-size and the average porosity on both clean and dust-loaded filters, and this will allow investigation of clogging mechanisms.

Engine Oil Filters

Claes Frennfelt of Volvo Powertrain ( Sweden ) underlined the importance of oil filtration in reducing the costs of operating a fleet of trucks and complying with the ever-tightening regulations on exhaust emissions. Oil lubricates, cleans and cools a truck diesel and is typically filtered in a bank of three large cartridges. Two of these operate at 60-80 litres/hour on the whole oil circuit, while the third, a finer “by-pass” filter operates at 8 litres min. The 40 liters of oil in the circuit is at 400 to 600 kPa.

Standard cellulose filters last 60,000 km while long life versions can do 100,000 km. For 150,000 km service intervals a synthetic blend filter is needed. These synthetic filter cartridges are much more expensive because they are not self-supporting. Other factors affecting oil service life are fuel quality (>500 ppm sulphur shortens the filter-life), exhaust gas recycling (reduces it by a third), biofuel use (a 30% biofuel blend halves it), and topography (hilly worse than flat). Compared with the 3 times more expensive synthetic oils, mineral oil works well up to 100,000km in normal climates. The low viscosity synthetics are needed in cold climates.

Plasma Coatings for Engine Air Filters

Marc Pauwels of Europlasma NV ( Belgium ) described how plasma could be used to polymerise a monomer onto the fibre surface to give a permanent coating. Filter media could be processed in a vacuum chamber on a roll-roll system, or complete cartridges could be processed batchwise. Hydrocarbon monomers give permanently hydrophilic coatings when treated in the presence of oxygen and fluorocarbon mixtures give oleophilic and hydrophobic coatings. The process is used to improve air filters for diesel engines by increasing the hydrophobicity of a PBT nonwoven filter so that it can pass the water decantation and repellency tests. The benefit is achieved without altering the dust holding capacity or filtration efficiency. It is also used on facemasks, air conditioner filters, battery separators and blood filters. The roll to roll process runs at 5 m/min and the current kit can take 60cm diameter rolls. Variable costs are €0.02/m 2 , said to be cheaper than a wet-chemistry approach and better for the environment. Asked what monomers were used to achieve permanent hydrophilicity on polypropylene, Mr Pauwels said this was a secret. Atmospheric plasma treatment did not work because the monomer loss proved too costly.

Predicting Filter Performance

Martin Lehmann, Head of Simulation Filter Elements at Mann and Hummel ( Germany ) said measuring the distribution of fibre diameters in a filter is the key to predicting filtration performance and Mann and Hummel had developed a new way of doing it. Using a single average diameter was clearly wrong and SEM or optical microscopes coupled with image analysis were poor. He used the new Matlab image analysis software but provided no details. Furthermore his work with cellulose filters assumed that the clearly flattened fibres in the filter were round with a diameter equivalent to their width. Asked about this, he felt the microscope “saw” the fibres as a dust particle would, so the assumption of roundness was OK. The technique could be used in QC.

Testing Single Pleats

Dr Harmut Sauter of Mahle Filtersystems ( Germany ) described the three scales of filter evaluation: micro, meso and macro where macro considers the whole filter in its housing, meso considers the filter alone and micro considers filtration at the interfibre level. Most automotive air filters are pleated so at the meso level, understanding the behaviour of a single pleat becomes fundamental to filter design. Furthermore, the single pleat lends itself to computational fluid dynamics (CFD) simulation of air velocities and hence comparisons of experimental with simulation data.

Air velocities were measured by particle image velocimetry (PIV) where the particles were too small to be separated by the filter. Static pressure measurements at one air velocity showed that the simulation technique provided roughly comparable data, the differences being attributed to the pleat changing shape under pressure. In fact in a real filter they were observed to stretch and vibrate and change the way the dust distributes itself. Maybe the use of a V shaped pleat was too simple. The N shape might represent the smallest filter element more exactly.

Classifying Air Filters

Dr Thomas Caesar, Manager Filter Technics, Freudenberg Nonwovens ( Germany ) observed that as energy prices and CO 2 emission concerns increased, the power consumption of air filters was being scrutinized. In the UK and Sweden where the data is available, 15% of all electricity consumption is by the fans used to handle air, and a third of this power was lost in pressure drops across the filters used to clean the air. So energy efficient air filters would help to save the planet and they therefore had to be classified according to their energy efficiency as well as their filtration efficiency. The target is to identify the types of filter which provide the highest possible particle removal efficiency at the lowest possible pressure drop, the complication being that both of these parameters varies with the life and dust loading of the filter.

Dr Caesar proposes the derivation of a “key energy performance” or kep number which is a function of the average efficiency from EN 779 using a 0.4 micron particle at 3400 m 3 /hr, and the average pressure drop derived from a loading of 800g of ISO A2 dust also at 3400 m 3 /hr. Kep numbers less than 1 are given “Energy Class 1” as the most efficient now possible, and kep numbers below 0.6 are given “Energy Class 5” being the least efficient. These 1 through 5 Energy Ratings would be used like refridgerator energy classifications so that filter buyers could choose the efficiency they could afford.

Asked if this was just for Freudenberg or would it become an official standard, Dr Caesar said he was working with ISO and would expect it to become an international standard in about 3 years. Freudenberg would be introducing energy efficiency labelling on their range by the end of next year. Is the market demanding this? “Basically yes”.

Nexylene PPS fibres

Dr Jens Neumann-Roderkich, Development Manager, Nexis Fibres (Germany) ran through their PPS brochure, reminding us that poly phenylene sulphide fibres offered exceptional thermal stability up to 200 o C (melting at 290 o C) and were therefore positioned, both from a performance and price viewpoint, between nylon 6 and the meta-aramids. Unlike the meta-aramids, they were melt spinnable and could be produced in crystalline and amorphous forms with differing properties. The stronger crystalline form exhibited a shrinkage of up to 8% on heating to 220 o C, and the amorphous form could be used as a stretchy binder fibre with identical thermal stability. They could be made into all forms of nonwovens, the needlefelts with 25% Nexylene woven scrim being offered as recyclable hot gas filters. There were several questions and one comment from the audience:

• The comment pointed out that this fibre could not be sold as a hot gas filter because it did not meet the required thermal stability at 250 o C.
• How did Nexylene compare with Japanese and Chinese sources of PPS? It was as good as the best Japanese and better than the Chinese, one supplier in China being poor for needlefelts. Furthermore neither the Chinese nor the US producers offer 1.3dtex
• Were special extruders, piping and spinpacks needed to handle the PPS melt? Yes, the chlorine residues necessitated this.
• Were there any problems with the gas in the workplace? No, it was within German limits without special ventilation.
• What were the wet-laid PPS nonwovens used for? Electrical insulation – in combination with other fibres.
• Was there still a PPS shortage. No, the market is now in balance and two or three producers have expansions underway.

Air Filtration Composite

Dr Carsten Heldmann, Global R&D Director of Fiberweb (Germany) is developing high performance air filtration media with a low pressure drop by combining fine-fibre meltblown (FFMB), spunbond and carded webs to form graduated filters. The FFMB has diameters between 0.6 and 1.4 micron and thus straddles the currently used boundary between micro and nano fibres. In one example of a 4-layer “TopFlow”composite, a top layer of coarse meltblown protected a layer of standard meltblown on top of a FFMB which had been laid on to a spunbond reinforcing layer.

Carded prefilters could be made from fibres of different denier on the same line to get an even coarser prefilter for use in HVAC. These could be laminated to the spunmelt structures using sonic bonding to minimise the loss of open area. The main message was that Fiberweb were now willing to combine their carding and spunmelt expertise to offer a wide range of air filtration products.

Needlefelts for Liquid Filtration

Heribert Kurt of Heimbach Filtration ( Germany ) said that scrim-reinforced needlefelts are generally better than woven fabrics in liquid filtration because they offer good capacity at lower pressure drop due to their bulk and permeability. In industrial process filters they can be designed to survive the often harsh chemical environments and have established themselves in vacuum belts filters, rotary drum filters and filter presses. Their main uses are in the production of:
• Minerals and zeolites, including ores, lime, diatomite, and active carbon.
• Chemicals, e.g. fertilisers
• Dyestuffs and pigments
• Pharmaceuticals and antibiotics
• Non-ferrous metals including copper, nickel and zinc and its oxides.
• Food additives

One example used a 300gsm woven monofil PET scrim with a microfiber needlefelt surface which had been densified to remove 2 micron particles of zeolite from the process liquor.

Asked how Heimbach deal with the “smile” and “frown” variations in basis weight across the width (that needlefelts are prone to and wovens not), Mr Kurt said they could compensate for these in careful calendering and heat setting to get uniform permeability. Fibre loss from needlefelts was another issue, and here again the surfaces could be stabilised in the calendar.

Liquid Filtration for a better society

Professor Richard Wakeman, a consulting engineer (UK) described the variety of filtration media now available and wondered whether they could help reduce the 2 million deaths that occur from preventable water borne diseases in regions of poor water quality. Delivering large quantities of water free from viruses and bacteria requires membrane-quality filtration, probably in the shape of membrane bioreactors (MBR). These are hybrid processes which combine active sludge anaerobic biotreatment with membrane filtration. Because the sludge fouls the membrane, bubble “aeration” is used to create turbulence and clean the membranes. Reuse of water in heavily populated regions is increasingly complicated by drug, herbicide and pesticide residues persisting through purification processes, and these require adsorbents like active carbon for their removal.

So where do the filters come in? Ahlstrom's Disruptor™ with active carbon was mentioned along with the industrialisation of nanofibre nonwovens.

Hybrid Membrane Technology

Dr Antoine Schelling of Dupont ( Switzerland ) described their new HMT filters designed to fill the gap between traditional filters and microporous films. HMT uses continuous filaments in the 0.2 to 0.6 micron range to achieve filtration efficiencies close to membranes with lower pressure drop. The filament diameters are, unlike meltblown or electrospun, controllable, and this yields controllable pore-size.

When tested according to ASTM-F795-88 with ISO ultrafine test dust in water against a cellulose/meltblown composite which targets removal of ~1 micron particles, HMT showed:
• An initial pressure drop between 0.25 and 1.2 kPa (for 5gsm and 31 gsm respectively) compared with 1.7 kPa for the composite.
• The 31 gsm HMT had an initial ability to remove 100% of 1 micron particles compared with 87% for the composite.
• The dust holding capacity of the 31 gsm HMT was 1.9 gms compared to 1.1 gms for the composite.

Applications in HVAC, bag, cabin air and cartridge filters are foreseen, as well as in battery separators. The technology is currently being used with a nylon 66 polymer on a 1.8m wide line and is commercially available in the 10 to 30+ gsm range as roll-goods.

Elmarco questions related to whether or not the process used electrospinning, what the productivity was, and what Dupont meant by high throughput did not yield any useful answers. Dr Schelling did however add that extra capacity would be added in the next year. The EDANA conference programme did describe HMT as “nanofibre from electrospinning”. The main diameter produced was 0.4 micron to match microglass.

Calvin Woodings

14 th October 2008