Are the Days of Petrochemical-Based Nonwovens Numbered?
Posted on: Wednesday, 25 June 2008, 03:02 CDT
By Wilson, Adrian
Cellulosic capacity is up and raw materials from biomass are emerging fast. Current pressures in terms of environmentally benign processing routes could quickly change everything for an industry like nonwoven fabrics, writes Adrian Wilson. Of the 1.725 Mt of nonwovens currently manufactured annually by spunmelt processing routes, around 75%, or 1.29 Mt, are employed in hygienic disposables- diapers, femcare and adult incontinence products. And 98% of such nonwovens are made of polypropylene (PP).
However, a number of industry observers believe this may be about to change.
Firstly, suppliers of polypropylene nonwovens have been battered by the cost of the raw materials for their products: "Price erosion for nonwovens suppliers to the hygiene market simply can't continue at present levels, or something will have to give" said one industry insider who wished to remain anonymous."The continuously rising cost of raw materials over the past two years - especially polypropylene - has been central to this, and it's linked to the oil price, which is showing no sign of going down.
"Nonwovens producers have continued to invest in the latest technologies, perhaps in the hope that the huge potential markets in India, China and elsewhere will finally start to take hold. But despite all the talk, the only real innovation required by our customers - and it doesn't matter if they are the premium brand- holders or the supermarket chains is a reduction in the cost of what we supply to them. We've become a feeder pack and it's a price-down situation."
ALTERNATIVES
As a consequence, many companies have started to look to alternative feedstocks, and especially polyester, which has become much more competitive with polypropylene, and is in many respects a much more versatile fibre. However, polyester, like polypropylene, faces a greater challenge in the public perception of disposable products derived from petrochemicals. Despite industry attempts to emphasise the comparatively minor impact of the landfill disposal of today's disposables, it has generally been perceived as unacceptable for many years.
Polypropylene fibre production at the FiberVisions' plant in Varde, Denmark.
Only the lack of convenient alternatives at almost any price has prevented outside influences from exerting action to try and remedy the situation.
NEW THREAT
Consultant Anders Moller though, is not alone in believing there is now a very real threat of politicians, government legislators and industry watchdogs becoming increasingly aware of the market availability of potentially biodegradable and sustainable alternatives, which despite high consumer demand are not being used because they cost too much.
Both vote-winning strategies whereby the politician is seen to be doing good for the environment and higher taxes could therefore easily be applied-legislating to tilt the balance against polypropylene and in favour of the biodegradables in such products, Moller points out.
The outcome, he believes, is likely to be the introduction of new taxes on polypropylene for disposables use, and sooner rather than later, most likely in Europe first, and then elsewhere within the next ten years.
Such action would render approximately 90% of the world's spunmelt capacity in need of costly modification to allow biopolymers to be processed, but the few existing multipolymer lines would be poised to profit immediately.
ENVIRONMENTAL IMPACT
Over the past 20 years, hygienic disposables have become thinner and their environmental impact has been reduced considerably: the calculated impacts on global warming and summer smog of baby diapers, for example, have fallen by 37% and 43% respectively from 1987 to today, and similar positive trends have been shown for incontinence products.
But over the same period, fibres and absorbents obtained from biomass, such as viscose rayon and wood pulp, have actually been progressively replaced with those derived from petrochemicals, namely PP, plastic films and super-absorbent polymers (SAPs).
During the 1990s, more 100% PP-based fabrics were added to diapers as cuffs and textile-like backsheets, and more recently 100% PP coverstock has switched from staple fibre to spunbond, largely due to the considerable improvements made in the formation of lightweight products made possible by the latest Reicofil technology.
TECHNOLOGY
Spunmelt technology was initially restricted to its inventors DuPont, ICI and Freudenberg, but transformed the industry when machines became commercially available,first from Lurgi and later from Reifenhauser (now Reicofil).
The latest Reicofil 4 system was introduced in 2002 and has subsequently become the industry standard.
Its main developments can be summarized as:
* the considerable increase of specific throughput;
* the ability to produce the same product with the same line speed but using less beams;
* the ability to make a softer product;
* control of the machinexross machine direction (MD:CD) ratio for greater uniformity and less waste at higher strengths; and
* full capacity for the production of polyester nonwovens.
With the Reico 4, the ability to independently control the cooling, stretching and lay down process steps means that the strength of products can be improved at reduced MD:CD ratios.
Modern Reicofl 4 lines dominate new investments in spunmelt technology.
Reico 4 technology has been incredibly successful. Over the past few years new lines have been put in place by the majority of major suppliers to the hygiene industry, including Advanced Fabrics (SAAF), Avgol, Fibertex, Fiberweb, First Quality, Fitesa, Freudenberg, Pegas, PGI, Providencia, Saudi German Nonwovens and Texbond.
BIOPOLYMERS
The growth of the biodiesel industry meanwhile, has resulted in more polymers from biomass, according to Polymers from Biomass, the latest report by SRI Consulting (SRIC).
There are many ways to obtain biopolymers, the report states. Polyethylene, for instance, is being produced from sugar cane via fermentation to ethanol, which can be dehydrated to ethylene.
The burgeoning production of biodiesel has yielded large amounts of the by-product glycerin, much of which is looking for a market. One of these markets, for example, is converting glycerin into epichlorohydrin, which is used to manufacture epoxy resins.
The report's author Bob Davenport says "Biomass derived polymers that are biodegradable include polylactic acid (PLA) and polyhydroxyalkanoates (PHAs). These bioderived polymers are not new, but only recently have seen markets develop into commercial volumes."
The report examines various monomers and co-monomers that can be produced from biomass, polymers derived directly from biomass and cellulosic polymers, as well as monomers formerly produced from petrochemicals that can be produced from biomass sources.
Like petroleum-derived products, bio-derived polymers can be used as fibres, films or engineering resins.
"Many factors are driving the use of biomass-derived polymers," adds Davenport."These include sustainability, domestic sourcing of raw materials that are annually reproduced, using materials and processes that are low on greenhouse gas emissions, and employing local farms and labour."
In manufacturing, biopolymers must perform economically and efficiently in their applications.
Whereas ethanol-based ethylene only faces the economic hurdle, many of the new polymers also face performance standards in their developing markets.
DIFFERENTIAL
General Manager of nonwovens industry body EDANA, Pierre Wiertz, says "Polymers derived from renewable sources that can be used to produce compostable plastics have been available in limited quantities for many years and have generally been used to produce plastic films for use in packaging and organic waste disposal applications. These films can also be used in absorbent hygiene products, but there is currently a cost differential between polyolefin resin and resin derived from these polymers of a factor of one to three.
"In a cost sensitive market such as absorbent hygiene products this presents a significant barrier" he adds. "Currently cost and availability restrict the use of such materials to absorbent hygiene products within low volume, specialized niche markets. This may well change, however, as availability increases and economies of scale emerge. More recent developments have seen the emergence of fibres made from polymers from renewable sources. Such fibres can be used in nonwoven applications and providing there is economic fibre supply these could be interesting developments for the future, which the absorbent hygiene products industry is monitoring.
"The environmental impact of such polymers must be measured by a complete cradle-to-grave life cycle assessment approach. The fact that they are derived from renewable resources does not automatically mean that they are better for the environment. All energy consumption and emissions occurring in the production process and its conversion into a substrate need to be considered.
"The broader sustainability issues surrounding these polymers are complex and include the [carbon dioxide] CO2 emissions that occur in the degradation of biodegradable materials, the ethics of using food crops, and the use of arable land to grow precursor materials." SAFETY TOO
"New materials must also be assessed in terms of their safety profile and their performance to ensure that there is no deterioration in either the performance or the safety of the final product, compared with those produced using existing materials."
"The absorbent hygiene product industry will continue to monitor opportunities to use sustainable alternatives to fossil fuel-based resource, while continuing to reduce the amount of material in its products, which is currently the most effective way to minimize their environmental impact."
CELLULOSICS
Cellulosic fibres are very likely to have a larger role in the future of nonwovens, which is good news particularly for Austria- headquartered Lenzing.
Nonwoven fabrics made from Lenzing's Viscose and Tencel fibres have been certified and registered as compostable materials by Din Certco, the certification organization of TUV Rheinland Group and the German Institute for Standardization (DIN).
Lenzing fibres are fully biodegradable, and unlike fossil fuel- based types decompose completely in soil burial or sewage treatment plants.
Lenzing is actively promoting the eco benefits of its fibres.
They are converted into pure water and CO2 which are reabsorbed during photosynthesis of green plants and converted into cellulose. In the past two years, massive expansions in viscose production and the pulp required to produce it have been announced-totalling in excess of half a million tonnes of new fibre'.
In the absence of this new capacity, viscose and lyocell prices have risen sharply and the market has been undersupplied due to high demand in textiles as well as nonwovens. Lenzing, not surprisingly, had a record year for fibre production in 2007 with its output reaching 560 kt, compared with 480 kt in 2006, mainly as a result of the start of production at a new plant in Nanjing, China(ii).
Research into cellulose and its derivatives is also increasing and includes work on the processes potentially capable of manufacturing low cost cellulosic nonwovens.
ABUNDANT
Consultant Calvin Woodings believes cellulosics have a strong chance of replacing polypropylene as the workhorse fibre for disposable nonwovens: "Cellulose is the only really abundant fibre- forming polymer produced and disposed within the carbon cycle" he says."Pure cellulose in the form of cotton, grown organically maybe, has the least environmental impact of any fibre and would be a low- cost yet valuable crop.
"Numerous processes exist for making cellulosic fibres from biomass, and all are potentially carbon-neutral because the parts of the biomass unsuitable for including in the finished fibres can be used to power the pulping, dissolution and fibre spinning operations."
Currently, existing nonwoven processes can convert these fibres into nonwovens, provided hydroentanglement is the bonding system. Cellulose can also be spunbonded in various ways to make self- bonded nonwovens or spunlaid.
"Assembling finished disposables without the help of thermoplasticity would be tricky" Woodings adds "but fabrics can be glued or even stitched together - by computercontrolled high pressure water needles - in the same way as these needles, at even higher pressure, are used as cutters."
Cellulosic fibres can also be converted into superabsorbents and such products are already used in wound care.
"Cellulosic disposables would be fully compatible with sewage systems, especially if the fibres are short and lightly bonded, or if the products are shredded through a waste disposal unit attached to the toilet" Woodings concludes. "Maybe as new infrastructure is developed and old infrastructure renewed, the installation of this option would take a load off landfill and reduce the environmental costs of collecting and transporting rubbish from homes to landfill or aerobic composters."
FiberVisions continues to expand its production of a variety of heavily-engineered bicomponent fibres.
BICOMPONENTS
One company seemingly unperturbed by all this is ES Fibervisions, which has just installed its thirteenth dedicated bicomponent fibre line at its European production site in Varde, Denmark, also its largest to date.
The latest line expands the production and supply capability of the company's range of polyethylene/polypropylene (PE/PP), ultra bulk, airlaid and speciality fibres for binding non-traditional fibre structures.
This capacity expansion follows the company's recent introduction of global production of new polyester bicomponent fibres. ES Fibervisions first added polyester fibres to its portfolio in 2000, with production concentrated at its sites in Japan and China. The addition of a polyester bicomponent line in 2006, at its Varde facility, and in North America in 2005, has resulted in globally standardized, high-quality polyester bicomponent fibres.
Bicomponent fibres provide a wide variety of performance and productivity related benefits to nonwovens. By binding together all types of fibres (such as glass, hemp, cotton, synthetics, metal, graphite and cellulose) manufacturers can achieve solutions through new fibre combinations or meet specific physical property requirements more cheaply.
The company's bicomponent portfolio also contains a broad range of sheath and core ratios, various polymer combinations, titres (from very fine to coarse), all cut lengths including tow, a variety of colours, high bulking, splittable, deodorant, compostable and biodegradable types. They are suitable for a variety of nonwoven applications including airlaid, wetlaid and carding, for through- air and thermal bonding, needlepunch and spunlacing.
According to the company's President and General Manager, Tom Zaiser, "Our bicomponent fibres deliver performance and productivity benefits that can add real value not just within the more traditional hygiene markets, but across the whole nonwovens industry."
Output
The total annual production of bicomponent fibres is now 236 kt according to Masuo Iwata of Chisso Polypro Fiber in Japan. Speaking at a recent seminar in Osaka organized by the All-Nippon Nonwovens Association (ANNA), Iwata said that of this figure:
* 81 kt was produced in Asia;
* 80 kt in Japan;
* 40 kt in the USA; and
* 35 kt in Europe.
These fibres have traditionally been employed in thermal bonded nonwovens for hygiene products, but have recently expanded into other fields including household, medical, agricultural and geotextile products.
The total global capacity of Chisso's own ES polyolefin bicomponent fibres - including that of the joint venture ES FiberVisions - is now an annual 73 kt. Chisso introduced ES fibres for thermal bonded nonwovens in 1974, licensing its technology to Danaklon (now FiberVisions) in Denmark in 1984. It subsequently set up an ES fibre line in Guangzhou, China, in 1995, and established the ES FiberVisons joint venture in 2000 to develop ES fibre worldwide.
ES fibres are composed of between 30-70% PP or polyester in the core and between 30-70% low-density polyethylene (LDPE) or high- density polyethylene (HDPE) or low-melt PP copolymer in the sheath.
The low-melt part sheath melts to bind the fibres in thermal bonding. A notable new application is in nickel-metal hydride (Ni- MH) battery separators in which 1.7-7 dtex segmented bicomponent fibres can be split into 16 portions of 0.1-0.2 dtex microfibres.
Chisso has also developed various types of new functional bicomponents including deodorant and anti-bacterial types, non- halogen frame retardants, electrostatic, heat resistant, pulp versions and hollow fibres.
Chisso's challenge now, Iwata concludes, is to move from commodity to speciality and from micron to submicron and nano grades, as well as continuing with the globalization of the ES fibre operations.
Further information
Anders Moller. E-mail: a_moller@bellsouth.net
Bernd Kluenter, Sales Director, Reifenhauser Reicofil.
Tel: +49-2241-93261-537. Fax: +49-2241-93261-744.
E-mail: Bernd.Kluenter@reicofil.com; http://www.reicofil.com
Susan Wright, SRI Consulting.
Tel: +1-650-384-4348. Fax: +1-650-330-1149.
E-mail: swright@sriconsulting.com; http://www.sriconsulting.com
Pierre Wiertz, General Manager, EDANA.
Tel: +32-2-740-1823. Fax: +32-2-733-3518.
E-mail: pierre.wiertz@edana.org; http://www.edana.org
Robert Gregan, Vice-president and General Manager, Lenzing Nonwoven Fibers.
Tel: +43-7672-701 -3342. Fax: +43-7672-918-3036.
E-mail: r.gregan@lenzing.com; http://www.lenzing.com
Calvin Woodings, Calvin Woodings Consulting.
Tel: +44-1926-633522. Fax: +44-1926-633571.
E-mail: cw@nonwoven.co.uk; http://www.nonwoven.co.uk
Niels Kaas Christensen, FiberVisions a/s.
Tel: +45-7994-2231. Fax: +45-7994-2201.
E-mail: fibervisions@fibervisions.dk; http://www.fibervisions.dk
Masuo Iwata, Chisso Polypro Fiber.Tel: +81-3-3243-6370.
http://www.chisso.co.jp
References
i See, for instance, Technical Textiles International, December 2007, Lenzing expands Austrian lyocell production, page 4; http:// www.technical-textiles.net/htm/f20071125.017733.htm
and Advances in Textiles Technology, May 2007, Lenzing builds viscose plant in India, page 10; http://www.technical-textiles.net/ htm/f20070504.129966.htm
ii Technical Textiles International, October/November 2007, Lenzing opens Chinese fibre plant, page 2; http://www.technical- textiles.net/htm/f20070926.428565.htm
Copyright International Newsletters May 2008
(c) 2008 Technical Textiles International : TTI. Provided by ProQuest Information and Learning. All rights Reserved.
Source: Technical Textiles International : TTI
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