Olefin polymers prepared by polymerization with treated alumina supported chromium

An olefin polymer prepared according to a polymerization process comprising contacting at least one mono-1-olefin with a catalyst produced by subjecting alumina to a treatment with a fluoriding agent, thereafter activating at a temperature of about 150.degree. to about 1000.degree. C. and thereafter introducing an organochromium component onto said alumina to produce said catalyst;

• wherein said alumina is also subjected to a silicating treatment prior to said activating;
• wherein said organochromium component is selected from:
• chromium compounds of the formula (I) or (II)
• Cr(R).sub.n (I)
• Cr.sub.x (R).sub.2x (II)
• wherein n is 3 or 4;
• x is 3 or more;
• R is --CH.sub.2 MR'R.increment.R'";
• wherein M is C, Si, Ge, Sn, or Pb;
• and wherein in a given compound the R groups are identical and R', R", and R'" are the same or different hydrocarbyl groups selected from aliphatic and aromatic radicals containing up to about 10 carbon atoms per radical;
• bis(cyclopentadienyl)chromium and substituted derivatives thereof;
• and pi bonded zerovalent organochromium compounds;
• and
• wherein said polymer has a melt viscosity within a range of 35 to 60 MPoise, an intrinsic viscosity within a range of 13 to 20 dL/g, and a density within a range of 0.94 to less than 0.95 g/cc.

An olefin polymer prepared in accordance with a polymerization process comprising contacting at least one mono-1-olefin with a catalyst produced by subjecting alumina to a treatment with a fluoriding agent, thereafter activating at a temperature of about 150.degree. to about 1000.degree. C. and thereafter introducing at least two organochromium components onto said alumina to produce said catalyst;

• wherein said alumina is also subjected to a silicating treatment prior to said activating;
• wherein said organochromium components are selected from octakis-(.mu.-trimethylsilylmethyl)tetra)-chromium(II), tetrakis-(trimethylsilylmethyl)chromium(IV), bis(cyclopentadienyl)chromium and dicumene chromium;
• and
• wherein said polymer has a melt viscosity within a range of 35 to 60 MPoise, an intrinsic viscosity within a range of 13 to 20 dL/g, and a density within a range of 0.94 to less than 0.95 g/cc.

An ethylene polymer prepared in accordance with a polymerization process comprising contacting ethylene with a chromium catalyst on a support produced by impregnating alumina with a liquid containing a source of phosphate ions and at least one aluminum salt and thereafter contacting with a neutralizing agent to form a gel of aluminum phosphate within the pores of said alumina and activating in air at about 300.degree. to about 900.degree. C., to give an ethylene polymer having environmental stress crack resistance of greater than 1,000 hours;

• wherein said support is prepared by mixing alumina with a solution containing Al(NO.sub.3).sub.3.9H.sub.2 O, H.sub.4 H.sub.2 PO.sub.4 and Cr(NO.sub.3).sub.3.9H.sub.2 O in an amount equal to or less than the pore volume of the alumina, adding aluminum hydroxide to cause a gel to form within the pores of the alumina;
• wherein said alumina had been modified by the addition of ammonium bifluoride and silica;
• and
• wherein said polymer has a melt viscosity within a range of 35 to 60 MPoise, an intrinsic viscosity within a range of 13 to 20 dL/g, and a density within a range of 0.94 to less than 0.95 g/cc.