Chromium catalyst compositions and polymerization utilizing same

Abstract From the Canadian patent

Improved mixed chromium catalysts useful in particle form polymerizations to produce readily processable high density polyolefin resins which also have high resistance to environmental stress cracking are provided. First and second chromium-containing catalyst components obtained using silica supports of different pore volumes and wherein one of the catalyst components also contains aluminum are employed for the preparation of the mixed catalysts. The polymerization process and products obtained using the above-described mixed catalysts are also described.