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In-reactor PP alloys made from multiple monomers.

Over the past two years, Himont Incorporated, Wilmington, Del., has quietly developed an unusual palette of alloyed PP copolymers and homopolymers made by the "Catalloy" process at plants in the U.S. and Italy. Many grades are already commercial in the U.S., including so-called reactor TPOs. In Europe, grades from the Catalloy process are test marketed under new trade names--Adflex (soft PP/EP-copolymer alloys) and Adstif (rigid homopolymer PP alloys). But in the U.S., they're sold under Himont's existing trademarks, HiFax and ProFax. Himont has been extraordinarily quiet about the plants, the process and the unusual properties it can make.

Catalloy is an in-reactor alloying process, not a resin or product name. It's a new way of introducing elastomers into the PP matrix and combining homopolymers to achieve different properties. Himont has published little about its Catalloy process by name, but a paper given at the SPO '92 conference last September (sponsored by Schotland Business Research, Princeton, N.J.) by Paolo Galli, president of Himont's Italian parent Montecatini Tecnologie SpA, describes the company's "reactor granule" technology.

Himont's spherical particles (already used in its Spheripol PP process) act like miniature reactors, Himont says, because polymerization takes place inside their porous structure as each successive monomer is added. The initial spherule forms a growing skin of polymer with the most active catalyst sites on the outside. In later reactor stages, Galli writes, "The surface layer's polymerization rate declines, |and~ the inner catalyst layer's active centers become most-favored polymerization sites... This results in a growing, spherical granule that provides a solid, porous reaction bed within which other monomers can be introduced and polymerized to form a polyolefinic alloy."

Each successive monomer is "intimately dispersed" within the matrix TABULAR DATA OMITTED polymers, Galli writes. Copolymers, terpolymers or multimonomer olefins can be formed inside the porous reactor granules, which grow to pellet size (3-5 mm). In this manner, a new polymer or polymers forms on the inner surface of the PP substrate, creating a "quasi-IPN" (interpenetrating polymer network). Galli's paper describes making a PP copolymer with 5-10% butadiene that is so reactive it can make the PP crosslinkable, or it can compatibilize blends and alloys even with styrenics.

The commercial Catalloy process is similar in concept to Himont's developmental Hivalloy technology except that where Catalloy is an olefinic alloying process, Hivalloy products are made by co-reacting the base PP spherule with up to 50-60% by weight of non-olefinic monomers. One example is a PS/PP reactor alloy, which can be melt blended with an engineering polymer like PPE, using the PS phase as the compatibilizer. Thus, completely novel materials have been produced (see PT, Sept. '91, p. 25).

The commercial Catalloy plants are "grass-roots" plants. A 176-million-lb/yr Catalloy plant in Ferrara, Italy, started up in February '91 and a second, 220-million-lb/yr plant in Bayport, Texas, in March '91. Himont sources also hint that a 440-million lb/yr Spherilene PE plant planned for Lake Charles, La. (around year end), may use the Catalloy process.

The only practical problem with the process is that multi-reactor alloying is so complex that it needs very fine controls, or it makes a lot of waste byproducts, a technical source at Himont says. There may also be a transportation cost because much of the secondary compounding is presently done at plants in Ohio and Tennessee.

DATA ON NEW PP ALLOYS

Here's a look at data sheets on materials being marketed in Europe. Supposedly all are also available in the TABULAR DATA OMITTED U.S. They range from very soft to very rigid, and include clear and high-heat grades. Most target extruded or injection molded packaging like blown film, rigid containers and thermoformed lids, where they are said to allow dramatic downgauging.

Soft materials are said to process on conventional extrusion and injection molding and even calendering equipment used for LDPE, PP and PVC. Adflex 7085, a blown-film grade, for example, is designed to replace LLDPE in heavy-duty shipping sacks. A 100-micron (Adflex) film can be substituted for 180-micron LLDPE film, Himont people say.

A soft film grade Adflex 7029, a calendering-grade Adflex 7036 (for artificial leather) and coex film grade Adflex 7042 are all related. In the U.S., they're all variations of HiFax CA10: 7036 is CA10, 7029 is CA10 with slip/anti-block additives and 7042 is a high-flow version of CA10 made by "visc-breaking" with peroxide (also called "controlled rheology"). Still other U.S. grades are CA30 and CA40, which are 10 and 20 MFI variations of CA10.

The fact that some of these PP grades can be calendered is also new (see PT, Feb. '93, p. 110). Normally heat and stress on film from high-speed rolling degrade polyolefins. In addition, experimental Adflex 7083, for injection molding and cast film, makes clear tough sheet for lids, also unusual for PP.

Rigid grades made by the Catalloy process are PP homopolymers (Adstif). Using different catalysts, the technology makes different molecular structures of homopolymer PP and mixes them. The homopolymers boast "extremely high stiffness, high gloss and high transparency," Himont's data sheet says. Some also have high-temperature capabilities for hot filling. They target extruded,thermoformed and injection molded packaging and durable parts.

A QUESTION ABOUT CATALLOY'S FUTURE

A big question for the Catalloy catalyst alloying system is what will become of it in the proposed marriage of the polyolefins businesses of Montecatini SpA with Royal Dutch Shell of the Netherlands. Himont has said its Catalloy process isn't for license. And the announcement last September by Montecatini and Shell of their merger intentions specifically excludes Shell Oil Co.'s Unipol venture with Union Carbide Chemicals & Plastics Co. Nonetheless, a Himont source close to the Shell/Himont negotiations says Catalloy is "one of the big things Himont brings to the table." So the questions remain, if Himont and Shell merge, will Catalloy get more or less development attention?
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Title Annotation:Polyolefins
Author:Schut, Jan H.
Publication:Plastics Technology
Date:Mar 1, 1993
Words:979
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