Scratch- and impact-resistant PP copolymers coming.

New polypropylene impact or block copolymers that combine unusually high ethylene content with high gloss and hardness are among copolymers being readied for the U.S. market by Sumitomo Chemical Co., Japan. The new highly scratch-resistant grades (Table 1 shows products being selectively sampled in the U.S. now), which contain up to 46% ethylene and ethylene/propylene blocks, are for appliance and automotive applications, including fenders and exterior trim. (PP impact copolymers of such high comonomer content would be considered TPOs in U.S. terminology.) They're novel because usually adding ethylene comonomer improves impact but softens PP material so it's easy to scratch. The specialty copolymers also have good low-temperature impact resistance.

The new copolymers are among grades to be made here by a new joint venture between Phillips Petroleum Co., Bartlesville, Okla., and Sumitomo's U.S. subsidiary incorporation, Sumika Polymers America Corp. in New York City. Last April, the two firms announced they were studying the possibility of merging their U.S. PP businesses, with a decision expected by year's end. Though formal approval hasn't been given, senior officials of both companies say the deal will go through, with an announcement likely in January.

Meanwhile, it's clear that Sumitomo aims to increase its stake in the U.S. plastics market. In August, Sumika announced a new partnership with Colonial Plastics of Dyersburg, Tenn., a unit of M.A. Hanna Co. Colonial, which claims to be the biggest independent custom compounder in the U.S., already compounds value-added thermoplastic grades for Sumitomo. Now Colonial will build a dedicated twin-screw compounding plant (designed jointly with Sumika) to make specialty filled thermoplastic compounds that Sumika will market. Although the compounding partnership does not appear to be contingent upon the Phillips/Sumika venture being realized, Phillips sources say the proposed joint venture would supply the resin for Colonial to compound. Colonial's new compounding plant is planned to start up next August.

NEW AUTOMOTIVE GRADES

In addition to the specially scratch-resistant materials, a half-dozen PP-copolymer and homopolymer grades are being readied for U.S. introduction including two bumper fascia grades, one for instrument panels, and three auto-trim grades. (Table 2 shows representative grades sold in Japan.) Of the fascia grades, BWE60X is a softer type, targeting polyurethane replacement, and BYE62X is a harder type for paintable bumpers. These are all talc-filled compounds except for GHH43, which is glass-filled. Two trim grades, GHH43 and BYH52, are high-stiffness homopolymers.

The proprietary homopolymers and block copolymers on which the compounds are based will probably be made domestically by the Phillips/Sumika partnership. That partnership would take over Phillips, existing 480-million-lb/yr bulk-phase, loop-reactor PP plant in Pasadena, Texas, which has already been converted to use Sumitomo very-high-activity catalyst.

Sumitomo's contribution to the joint venture will be to build a new 270-million-lb/yr, multi-reactor gas-phase series to make the proprietary block copolymers. The series is reliably said to be three reactors; Sumitomo confirms only that all reactors are gas phase. Construction is expected to start in early 1994, and it would start up in 1995.

It will make homopolymer in the first gas-phase reactor, then add high ethylene content in the following reactors. The technology is said to make copolymers with very large blocks of PE, so the resulting copolymer is reportedly competitive in properties with both compounded TPOs and so called reactor TPOs made by competing multi-reactor processes for the same automotive applications. Sumitomo uses its multi-reactor technology in Singapore to make dozens of appliance grades, but has never licensed the technology.

The Sumitomo specialty copolymers, neat out of the reactor before subsequent compounding, are said to have 80-90% of the scratch resistance of ABS and polycarbonate. Proprietary filling and compounding are needed for some grades. In Japan, they,re used commercially for Yamaha motorcycle fenders, washing-machine parts and other durable goods.

Sumitomo also makes specialty terpolymers of ethylene, propylene and butene for extruding BOPP film. These grades, marketed in Japan as "Excellent SP," aren't yet in Sumitomo's U.S. plans. (CIRCLE 24)