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US006231936B1
(12) United States Patent ao) Patent No.: us 6,231,936 Bi
Kozimor et al. (45) Date of Patent: *May 15,2001
(54) RADIATION TOLERANT POLYPROPYLENE AND ITS USEFUL ARTICLES
(75) Inventors: Renee A. Kozimor, Hawthorn Woods, IL (US); Robert C. Portnoy, Houston, TX (US)
(73) Assignee: Exxon Chemical Patents, Inc.,
Baytown, TX (US)
( * ) Notice: This patent issued on a continued prosecution application filed under 37 CFR 1.53(d), and is subject to the twenty year patent term provisions ol 35 U.S.C. 154(a)(2).
Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
(21) Appl. No.: 08/854,000
(22) Filed: May 9, 1997
Related U.S. Application Data
Continuation of application No. 08/521,082, filed on Aug. 29, 1995, now abandoned.
Int. ( I. B32B 27/32
U.S. CI 428/34.7; 428/35.7; 428/500;
428/515; 428/516; 428/511; 428/461; 525/240; 524/86; 524/106; 522/211; 426/240; 422/22;
206/530; 206/531
Field of Search 525/240; 422/22;
522/112, 911; 524/108, 86; 206/530, 531; 426/240; 428/515, 516, 500, 35.7, 34.7,
461, 511
References Cited
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FOREIGN PATENT DOCUMENTS
0 318 049 Al 5/1989 (EP) .
0 380 145 Al 1/1990 (EP) .
0 431 475 A2 6/1991 (EP) .
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OTHER PUBLICATIONS
Michael Jefferies, "The Marketing Challenge Created By
Single Site Catalysts in Polyolefins", 1991 Specialty Poly-
olefins Conference, Sep. 24, 1991, p. 43-55.
M.R. Rifi, H.K. Ticker and M.A. Corwin, "FlexomerTM
Polyolefins: A Bridge Between Polyethylene and Rubbers",
Union Carbide Sales Bulletin, 1990.
R.C. Portnoy and V.R. Cross, "Method for Evaluating the
Gamma Radiation Tolerance ol Polypropylene for Medical
Device Applications", ANTEC '91 (1991).
L. Wild, T.R. Ryle, D.C. Knobeloch, and I.R. Peat, "Deter-
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* cited by examiner
Primary Examiner—Paul Thibodeau
Assistant Examiner—D. Lawrence Tarazano
(74) Attorney, Agent, or Firm—Darrell E. Warner; Gerald
L. Harris; Frank E. Reid
(57) ABSTRACT
Provided are articles such as packaging materials and medical devices having enhanced tolerance to radiation and heat, produced from a blend ol from about 99% to about 50% by weight homo or copolymerized polypropylene and about 1% to about 50% by weight polyethylene produced by singlesite catalysis, such polyethylene having a MWD between about 1 and about 4, and a CDBI greater than about 45%. Optionally, other blend components may be added, such as hindered amine stabilizers, secondary antioxidants, clarilying nucleators and secondary antioxidants. Also provided are processes for producing such articles.
53 Claims, 5 Drawing Sheets
