Blend of three ethylene polymers

• US 4,336,352 A
• Filed: 08/11/1980
• Issued: 06/22/1982
• Est. Priority Date: 08/24/1979
• Status: Expired due to Term

• Current Assignee: Asahi Kasei Kogyo Kabushiki Kaisha (Asahi Kasei Corporation)
• Original Assignee: Asahi Kasei Kogyo Kabushiki Kaisha (Asahi Kasei Corporation)
• Inventors: Sakurai, Hisaya, Ikegami, Tadashi, Katayama, Yoshihiko, Mizutani, Shigeru
• Primary Examiner(s): Levin, Stanford M.
• Application Number:
  US06/176,739
• Time in Patent Office: 680 Days
• Field of Search: 525/53, 525/210, 525/216, 525/232, 525/240
• US Class Current: 525/240
• CPC Class Codes: C08F 110/02 Ethene
• CPC Class Codes: C08F 2/001 Multistage polymerisation processes characterised by a change in reactor conditions without deactivating the intermediate polymer C08F295/00, C08F297/00 take precedence
• CPC Class Codes: C08F 210/08 Butenes
• CPC Class Codes: C08F 210/16 Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• CPC Class Codes: C08F 2500/07 High density, i.e. > 0.95 g/cm3
• CPC Class Codes: C08F 2500/12 Melt flow index or melt flow ratio
• CPC Class Codes: C08F 2500/13 Environmental stress cracking resistance
• CPC Class Codes: C08F 2500/14 Die swell or die swell ratio or swell ratio
• CPC Class Codes: C08L 2205/02 containing two or more polymers of the same C08L -group
• CPC Class Codes: C08L 2205/03 containing three or more polymers in a blend
• CPC Class Codes: C08L 23/06 Polyethene
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials

Abstract

A polyethylene composition comprising a mixture of three kinds of polyethylenes (A), (B) and (C) characterized in that:

(i) the viscosity average molecular weight of (A) is 1,000-100,000, the viscosity average molecular weight of (B) is 100,000-1,000,000, the viscosity average molecular weight of (C) is 400,000-6,000,000, the molecular weight ratio of (B) to (A), i.e. B/A, is 2-200 and the molecular weight ratio of (C) to (B), i.e. C/B, is 1.5 or more.

(ii) the mixing ratio of (A) to (B) is 30/70 to 70/30 and the mixing ratio of (C) is 1-10% by weight based on the total composition, and

(iii) the melt index of the composition is 0.001-1, and a process for producing said composition. This polyethylene composition is excellent in physical properties in that it has an appropriate die swell, a high melt tension and an excellent moldability and exhibits a high stiffness and a high ESCR.

Claims

1. A composition comprising a mixture of three polymers (A), (B) and (C) which are selected from the group consisting of homopolymers of ethylene and copolymers of ethylene with a member selected from the group consisting of propylene, butene, pentene, 4-methylpentene-1, hexene, octene, and decene, the composition being characterized in that:

(i) the viscosity average molecular weight of (A) is 1,000-100,000, the viscosity average molecular weight of (B) is 100,000-1,000,000, the viscosity average molecular weight of (C) is 400,000-6,000,000, the molecular weight ratio of (B) to (A), (B/A), is 2-200, and the molecular weight ratio of (C) to (B), (C/B), is 1.5 or more,

(ii) the mixing ratio of (A) to (B), (A/B), is 30/70 to 70/30 and the mixing ratio of (C) to the total composition is 1-10% by weight,

(iii) melt index of the composition is 0.001-1, and

(iv) density of the composition is 0.976-0.935.

2. A composition according to claim 1, wherein melt index of the composition is 0.005-0.5.

3. A composition according to claim 1, wherein the viscosity average molecular weight of (C) is 600,000-4,000,000.

4. A composition according to claim 1, wherein the viscosity average molecular weight of (A) is 5,000-70,000, the viscosity average molecular weight of (B) is 300,000-800,000 and the molecular weight ratio of (B) to (A), (B/A), is 5-100.

5. A composition according to claim 1, wherein the molecular weight ratio of (C) to (B), (C/B), is 2 or more.

6. A composition according to claim 1, wherein the mixture ratio of (C) is 3-8% by weight based on the total composition.

7. A composition according to claim 1, wherein each of (A), (B) and (C) is a homopolymer of ethylene.