By Kikuko Tagawa
Polyvinyl chloride (PVC) is an extremely popular material used in a wide variety of applications, including construction, industrial fabrics, filtration, medical products, food wraps, toys, and many others. This inexpensive material combines strength and workability and excels in weatherability and chemical resistance. PVC appears to be the ideal material for many industries, but in the last few years the material has raised concerns about its impact on human health and the environment.
According to Greenpeace, the manufacture, incineration or accidental burning of PVC forms large quantities of dioxin. Dioxin (PCDD/F: polychlorinated dibenzodioxin and polychlorinated dibenzofuran) is one of the most toxic substances known, and has been found to cause cancer and reproductive disorders. There are also concerns within the environmental and toxicology communities about chemicals added to PVC to give it specific properties for building product applications. The plasticizer di(2-ethylhexyl)phthalate (DEHP), for example, has been a focus of recent concern. (See the following Web page for more information on this topic: archive.greenpeace.org.)
However, the American Society of Mechanical Engineerâ€™s (ASME) 1995 research report on chlorine input into and dioxin output from a variety of incinerators worldwide shows little evidence of a link between chlorine and dioxin formation in incinerators. The report, which focuses mainly on full-scale incinerators, concludes, “The hypothesis that fuel chlorine content and combustor flue gas PCDD/F concentrations are related was not confirmed by the data analyzed in this study.”
Even if we allow that PVC contributes to dioxin production, better incineration techniques could significantly reduce the production of dioxin, not just from PVC but from all incinerated waste. Anything combusted completely in the proper way will produce fewer emissions. According to the Vinyl Industry and Environmental Council (VEC), dioxins exhausted from waste incinerators in Japan in 2000 were at only 25 percent of levels found in 1997. This is the result of government efforts to maintain efficient incinerators.
Although efforts at building such incinerators have seen some results in Japan, efficient incinerators that provide “perfect combustion” are not very common yet. “Effective efficient incinerators and control of PVC waste distribution will be part of the solution to the issue,” says Hiroyasu Sakakura, chief executive officer of Klark Co. Ltd., Nagoya City, Japan.
“I do not agree with the idea of blindly considering PVC as the bad guy. PVC may be one of the best materials ever invented, physically and economically. It would be unfortunate if the world were deprived of such a useful material,” agrees Yoshio Kitamura, general manager of Taiyo Kogyo Corp., Tokyo.
Various efforts have been made to recycle PVC without creating hazardous materials. Recycled PVC has been used in such products as flooring material, pipes, wire coatings, golf course matting, and cements. According to VEC, PVC waste amounts to a little more than one million tons annually; more than 30 percent of it is recycled, the highest recycling rate among plastics.
Many research and development laboratories in the fabrics industry are seeking cleaner substitutes for PVC. Some firms have succeeded; cleaner substitutes exist for almost all uses of PVC. But, the physical or economic properties of the substitutes are not yet as attractive as PVC’s properties.
FR for fabric shelters
At the November 2001 Kitakushu-Fair, a new PVC substitute was experimentally used in twenty pavilions. The material, called Ecoloshel, was co-developed by Toray Industries Inc. and Taiyo Kogyo. “Chlorine and bromine, which can produce dioxin emissions when burnt, are not used in Ecoloshel. It contains no material known to generate environmental hormones. And yet, it excels in low-temperature resistance, weatherability and abrasion resistance, thus serving longer than conventional PVC materials,” says Kazuhiro Morimoto, general manager of Industrial Material Department of Toray Industries. The material has been on the market for fabric shelters since November 2001.
“Several manufacturers are developing non-PVC material, but Ecoloshel is the first halogen-free and fire-retardant material in the industry. It is also the first halogen-free material approved for fabric structures by the Membrane Structures Association of Japan,” says Morimoto.
Ecoloshelâ€™s composition is flexible: The resin can either be blended with the flame-retardant agent and urethane resin coated to both sides of polyester fabrics or coated on one side and laminated with film on the other for those customers who want high translucency in the material. Because phosphorus system compound is used for the fire-retardant agent, the material has an equal or better performance than conventional PVC with less potential risk to the environment. According to Morimoto, Toray started developing the new material in 1999.
“Ecoloshel is currently being recycled thermally [it is burned and the heat energy utilized] but we are now trying to incorporate recycling in other ways, such as using recycled PET fibers for Ecoloshelâ€™s base fabric,” says Morimoto.
Recyclable polypropylene sheet
Now, Kanbo Pras Corp., Tokyo, has developed the Kanbo Apple Star – RR (recyclable and returnable) series of 100-percent polypropylene, environmentally friendly sheet. The product consists of a polypropylene sheet coated with a special polypropylene resin to make it RF weldable. “The fabricator will be able to utilize current welders when fabricating the material,” says Kenichi Kogo, director of Kanbo Pras Corp. The company is now co-developing a fire-retardant material for fabric structures using Pylen Super Valzer PII™ provided by Mitsubishi Rayon. Some versions of Apple Star have been approved as fire-retardant materials by the Japan Fire Retardant Association. These are the first fire-retardant polypropylene materials publicly approved.
“Since the preservation of the environment is our companyâ€™s principal, we have been promoting the ‘4 R Suggestions’: reject legally controlled materials, reduce industrial waste, reuse and recycle the material. This polypropylene sheet was developed according to that principal,” says Kogo.
Kanbo Pras is preparing a recycling system of their RR products that will provide for collection and recycling of used products. The company aims to provide a wider range of clean materials for industrial sheets, covers and membrane structures to meet the needs of the market.
Clear polyolefin sheet
Polyolefin is another substitute for PVC. Diatex Co. Ltd., Tokyo, has developed Eco Piolan, a PVC-like polyolefin material for industrial applications, including shelters, greenhouses, covers, and bags. It is reinforced by polyolefin tape yarn.
“The material stays soft in cold weather and Eco Piolan pool shelters in northern Japan were very well received. The fabric is lightweight, heat sealable, and easy to handle. It has almost the same transparency, UV resistance, tenacity, elongation and tearing strength properties as PVC. The only property it lacks is fire retardancy,” says Fumihiko Obuchi of Diatex. Clear and frosted versions are available, which have slightly different properties.
Unfortunately, unlike Eco Piolan, most of these products cannot compete with conventional material prices; they cost more than the conventional products. Although Japanâ€™s law on promoting “green” purchasing (a law promoting the procurement of eco-friendly goods and services by the state and other entities) has been enforced by the government, Japan’s enduringly sluggish economy prevents the diffusion of these products. The distribution routes are limited to public facilities and a few other particular facilities. “Prefabricated housing contractors are good customers, as they add value to individual houses using non-PVC material for end-users. Also, there are many companies in the high-tech industry who ask us to provide non-PVC material,” says Kogo. There is a tendency for environmentally sensitive companies to resist PVC, although it is still controversial.
Some say the key word for the new century is “environment.” The time has come for all of us, as both technical fabric businesses and end users, to think about the Earthâ€™s ecology, upon which we all depend.