Constrained geometry catalyst technology

Chum, P.S., Kao, C.I., and Knight, G.W., Structure/property relationships in polyolefins made by constrained geometry catalyst technology, Plast. Eng., June 1995, 21-23. 

Deposition of paRmt on the constrained geometry catalyst technology (CGCT) based on the transition metals, M = Ti, Zr, Hf. The resulting PO is substantially linear. The preferred composition comprises 10-95 wt% of homogeneously branched linear a-olefin copolymta (p = 0.930-0.965 g mL ", MWD = 1.8-2.8, single r )... 

Orlando, FL, 21st-23rd Sept.1999, paper 28 ANTIDEGRAD ANT SYSTEM DEVELOPMENT FOR EPDM PRODUCED VIA CONSTRAINED GEOMETRY CATALYST TECHNOLOGY... 

Ho, T. Martin, J. M. Structure, Properties and Applications of Polyolefin Elastomers Produced by Constrained Geometry Catalysts. In Metallocene-based Polyolefins Preparation, Properties and Technology, Scheirs, J., Kaminsky, W., Eds. Wiley Chichester, 2000 Vol. 2 175. 

Over the last two decades, organometallic complexes have been at the heart of many of the key advances in metal-mediated alkene polymerization technology, with many examples now reaching the early stages of commercialization. While early transition metal complexes (e.g., metallocenes, constrained-geometry catalysts) have led the way, the advent of late transition metal catalysts has presented a rich library of highly active systems that can be employed... 

In the USA Exxon Chemical and Dow Plastics were the leaders in the metallocene technology. While Exxon explored both mono- and bis-cyclopentadienyl metallocenes, Dow focused on constrained geometry catalysts based on Ti-monocyclopentadienyl metallocenes. Exxon first produced metallocene-based polymers with its Exxpol catalysts in 1991. Dow uses its INSITE technology to make ethylene-octene copolymers, introduced in 1993. Copolymers with up to 20 wt% octene are sold as AFFINITY plastomers, competing with specialty polymers in packaging, medical devices, and other applications. Dow, producing its own catalyst, considers that it leads to the uniform introduction of comonomers and long-chain branches that improve processability of otherwise linear polymers. 

Ethylene/styrene copolymers are presently available commercially from Dow Chemical Company using Dow s constrained geometry catalyst (INSITE) technology. These novel, random, semicrystalline copolymers contain 20-80 wt% styrene. The copolymer melting points decreased from about 90°C to 45°C with increasing styrene content from 20 to 45 wt%, respectively [56,57]. 

Asahi Chemieal Industry Co., Ltd. and the Dow Chemieal Company have sueeeeded in producing commercial HOPE resin products never before realized with conventional catalyst technology. The combination of Dow s INSITE constrained geometry catalyst with Asahi s slurry process has made possible the production of HOPE resins with significantly improved mechanical strength and enviromnental stress crack resistance (ESCR), compared with HOPE produced from Ziegler Natta (ZN) catalysts and conventional metallocene catalysts. 

ELITE resins are produced via INSITE Technology, a constrained geometry catalyst and process technology developed by The Dow Chemical Company that provides extraordinary control over polymer arehiteeture. 

The first commercial process for making LLDPE was the Sclair technology developed by Dupont Canada and now implemented by NOVA Chemicals. This process involves high-temperature solution polymerization. Much LLDPE is now made in gas-phase reactors with butene or hexene as the co-monomer. The constrained-geometry catalyst (CGC) is a metallocene catalyst developed by Dow Chemical for the manufacture of linear, very-low density polyethylene resins by solution polymerization with octene as the comonomer. For a given co-monomer content, the solid-state density is lower for octene than for lower a-olefins. 

EPM [poly(ethylene-co-propylene)] and EPDM [poly(ethylene-co-propylene-co-5-ethylidene-2-norbomene)P can be metallocene catalyst polymerized. Metallocene catalyst technologies include (1) Insite, a constrained geometry group of catalysts used to produce AfiGnity polyolefin plastomers (POP), Elite PE, Nordel EPDM, and Engage polyolefin elastomers (POP) and (2) Exxpol ionic metallocene catalyst compositions used to produce Exact plastomer octene copolymers.2 Insite technology produces EPDM-based Nordel IP with property consistency and predictability (see Sec. 3.2.2). 

Catalyst summation The new polymerization catalysts with conventional commodity feedstocks have produced a wave of new plastics that became obvious early during the 1990s. The terms used with this new technology include metallocene, single-site, constrained-geometry, and syndiotactic. 

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