PPS

PPS Is a Competitive Segment

Toray, Ticona (Celanese) and CP Chem (Chevron Phillips) supply PPS resin. Inspec, Amoco Fiber and Toray make the fibers.

Toray Industries, Inc. acquired the polyphenylene sulfide (PPS) fiber unit of American Fibers & Yarns Co. (AFY). The acquisition boosted Toray’s share of the worldwide PPS fiber market to more than 60 percent. Toray targeted PPS fiber sales of 1 billion yen in fiscal year 2002.

In addition to PPS fiber, AFY, which is headquartered in Cumming, GA, produces and markets polypropylene fiber for automobile and home interior applications. The company enjoys approximately 50 percent of the global PPS fiber market, supplying the material mainly for dust chamber filter applications. Toray launched a polyphenylene sulfide resin business in 1986 and in 1998 it began PPS fiber production after constructing related facilities at its plants in Ehime and Okazaki.

Worldwide PPS fiber demand currently stands at approximately 1100 tons per year. The market is shared by the United States (approximately 25 percent), Europe (approximately 50 percent), Japan and Asia (approximately 17 percent) and Australia (approximately 8 percent).

Toray constructed a PPS staple fiber production facility (1500 tons/year) at its Ehime plant and built a PPS filament yarn production facility (100 tons/year) at its Okazaki plant. Both facilities came on-stream in February 1998.

Inspec Fibres supplies PPS fibers under the trade name Procon. Ticona, part of Celanese, supplies the Fortron® polyphenylene sulfide resins. Ryton is the trade name for the PPS resins supplied by CP Chem (Chevron Phillips Chemical Company LP). Fibers produced by Amoco Fabrics and fibers using Ryton® polyphenylene sulfide (PPS) have been used in the We Energies Valley Power Plant; with 18,000 flue gas bags, it is one of the largest installations of Ryton® PPS-made filter bags to date.

The use of engineering thermoplastics such as linear polyphenylene sulfide (PPS) offers nonwovens manufacturers a diverse platform from which to expand their product offerings and enter new product niches that often involve displacing other plastics, and materials such as stainless steel, ceramics and glass. In Nonwovens Industry, Ramesh Srinivasan of Ticona, the technical polymers business of Celanese AG, discusses the potential offered by linear PPS. Most durable and disposable nonwovens are made of polypropylene (PP). Linear PPS is configured to work well in nonwovens processes and can be spun efficiently on conventional polypropylene and other nonwovens forming machines.

PPS is stable, tough and chemically resistant over a wide range of temperatures. It is made in branched and linear forms. Branched PPS, the older of the two forms, is more rigid and generally unacceptable for extrusion.

Linear PPS is a semicrystalline material (60-65 percent crystalline). It melts at a relatively high temperature and has a glass-transition temperature of about 90° C. It resists acids, bases, alcohols, oxidizing bleaches, hydrocarbons and many other chemicals at elevated temperatures for extended times. There is no known solvent that dissolves linear PPS at temperatures below 200° C. It is also inherently flame retardant so it needs no added flame retardants.

Linear PPS resists hydrolysis so well that its tensile strength and elongation show little or no decrease after being exposed to water at 95° C for more than 1000 hours at 15 psi. Unfilled linear PPS has a continuous operating temperature of 170° C. Filled grades have continuous operating temperatures up to 240° C.

Linear PPS is a good choice for use in harsh environments having high temperatures and corrosive atmospheres, such as baghouse and flue gas filters in coal-fired boilers, cogeneration units and cement kilns. This PPS is also used in liquid filtration, especially for hazardous materials at temperatures up to 205° C in the chemical, petrochemical, pharmaceutical, food and beverage industries.

Linear PPS nonwovens can be made by various extrusion methods. For instance, meltblown PPS fabrics are excellent filter media, while spunbond PPS provides strong backing for filter media. Also, netting made with PPS can replace stainless steel mesh in filter supports. PPS staple fibers in various deniers and cross sections have been used as felt substrates needlepunched composites.

INSPEC PRODUCTS

Inspec is supplying fibers to meet the range of power plant needs. The biggest  recent development  is the success of blends. The higher price P84 fiber can be added to PPS to provide greater filtration efficiency and lower pressure drop.

Having three fibers available in the portfolio Inspec Fibres offers a complete range of high tech fibers to be used as filter media in industrial coal-fired boilers, minerals processing, asphalt plants, cement production, soil remediation, waste incineration, power co-generation and other high temperature baghouse applications.

PAN Dolanit, PPS Procon and P84 polyimide fibers are especially applicable for high temperature filtration. The filtration efficiency and combined differential pressure development of filter media made out of these fibers is demonstrated by the test results obtained with VDI 3926 measurements.

With Dolanit, Procon and P84 Inspec Fibres meets most of the requirements of gas filtration with regard to temperature, chemical resistance and filtration performance.

VDI 3926 tests confirm the improvement of filtration efficiency and reduction of differential pressure when P84 fibers are blended into the surface of PAN, PPS or PTFE needle felts.

Several installations in the field confirm these findings.