HOUSTON - Polypropylene makers are developing new resins with diverse properties using traditional and metallocene catalyst technologies. In papers delivered at the Specialty Polyolefins '96 conference Sept. 25-27 in Houston, four PP makers talked about new resins:
PCD Polymere GmbH of Linz, Austria, has developed supersoft PP products that it hopes to introduce to the market soon.
Rexene Products Co. of Dallas has developed a line of flexible polyolefins that it is targeting at medical applications.
Montell USA Inc. of Wilming-ton, Del., has combined semicrystalline olefins such as PP with amorphous monomers to produce polymers that combine the best aspects of each class of materials.
And Exxon Chemical Co. of Houston has developed new PP resins for applications including biaxially oriented and cast films.
Markus Gahleitner, research scientist and project manager for PCD, said his company used patented catalyst technology acquired from DuPont Co. in 1991 to produce an extremely soft PP material with ``significant'' elasticity.
PCD Polymere characterized the PP polymer chain as having a stereoblock arrangement of isotactic and atactic PP segments. The polymer has softness and elasticity properties similar to cross-linked elastomers while retaining complete thermoplastic properties, Gahleitner said.
PCD Polymere believes the market for its polymers could be between 100 million and 400 million pounds in Western Europe alone, and said it may build a commercial facility to produce the polymer.
The company would target applications such as medical and sanitary films, pouches and tubing, packaging, bottles for cosmetics and pharmaceuticals, sealing profiles, roof and construction membranes, flooring and furniture products, and modifiers for PP and a variety of other resins, Gahleitner said.
Joseph T. Bonk, marketing manager for Rexene, said his company has developed its new line of flexible polyolefins to replace other resins in applications for medical products such as medical bags, gowns, drapes, covers, diapers, tubing, tapes and bandages, and packaging.
Rexene's FPOs have a high degree of clarity and impact resistance, can be sterilized by radiation and printed on, and offer significant gauge and weight reductions in a variety of medical applications, Bonk said.
Rexene's new FPOs can be used in other applications beyond the medical industry, according to Bonk.
Kenneth R. Dargis, director of business development for Mon-tell USA, said his company has used new monomer systems to produce new resins that it is selling under the Hivalloy trade name.
Montell's combinations include PP with unreinforced and toughened styrene copolymers, PP with polymethyl methacrylate copolymers, and PP with styrene/ maleic anhydride terpolymers, Dargis said.
The SMA alloys produce a resin alloy that has enhanced resistance to heat, while the PMMA alloys produce a resin alloy with enhanced weatherability and color properties, he said.
Montell has used its new alloys to replace acetal resins in an appliance application, to replace a polycarbonate/polybutylene terephthalate alloy in a recreational vehicle application and to replace polycarbonate in an electronic application, he said.
In each case, Dargis said his company's alloys provided similar or improved performance characteristics at lower prices.
James J. McAlpin, development leader for Exxon Chemical, said his company's new PP resins can be used to make biaxially oriented films at lower temperatures and higher line speeds with improved shrink capability.
Exxon's metallocene-based PP resins can be made into films at temperatures 27§ F lower than conventional resins, and can survive stretching tests at temperatures nearly 36§ F below their melting points and at 54§ F below the processing temperatures of comparable conventional resins, McAlpin claimed.
However, he noted that the resins, as expected, could not match conventional resins in high-speed stretching in packaging lines.