Ionomer/high density polyethylene blends with improved flow

• US 6,596,815 B1
• Filed: 01/25/2002
• Issued: 07/22/2003
• Est. Priority Date: 01/25/2002
• Status: Active Grant

• Current Assignee: Dow Global Technologies LLC (Dow, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Feinberg, Stewart Carl
• Primary Examiner(s): Nutter, Nathan M.
• Application Number:
  US10/057,117
• Time in Patent Office: 543 Days
• Field of Search: 525/191, 525/207, 525/221, 525/240
• US Class Current: 525/191
• CPC Class Codes: C08L 23/06 Polyethene
• CPC Class Codes: C08L 23/08 Copolymers of ethene C08L23/16 takes precedence
• CPC Class Codes: C08L 23/0869 Acids or derivatives thereof
• CPC Class Codes: C08L 23/0876 Neutralised polymers, i.e. ionomers
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 51/06 grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond

Abstract

An ionomer/high density polyethylene (HDPE) blend with improved flow (e.g., lower viscosity) can be achieved without significantly degrading physical properties such as impact resistance and tensile strength by the addition of low molecular weight ethylene/acrylic acid copolymer (e.g., so-called acid wax polymer derived from copolymerizing at least 5 weight percent and preferably greater than 9 weight percent acrylic acid and/or methacrylic acid with ethylene and having a melt index, ASTM D1238, preferably greater than 900 dg/min and preferably greater than 5,000 dg/min). The blend may further have for every one hundred parts by weight of ionomer/high density polyethylene blend from one to twenty parts by weight polyethylene modified with from 0.2 to 5.0 weight percent maleic anhydride comonomer as an impact resistance additive. The blends exhibiting improved flow characteristics according to the instant invention are particularly useful in the manufacture of automotive parts, panels and the like having a “class A” surface.

Claims

1. An ionomer/high density polyethylene blend having improved flow properties comprising for every one hundred parts by weight of ionomer/high density polyethylene blend from one to twenty parts by weight low molecular weight copolymer of ethylene and at least one other comonomer selected from the group consisting of acrylic acid, methacrylic acid and mixtures thereof, wherein said low molecular weight copolymer has a melt index (ASTM D1238) of greater than 350 dg/min and an acrylic acid and methacrylic acid combined comonomer content of at least 5 weight percent.

2. An ionomer/high density polyethylene blend of claim 1 wherein said low molecular weight copolymer of ethylene and at least one other comonomer has a melt index of at least 900 dg/min.

3. An ionomer/high density polyethylene blend of claim 1 wherein said very molecular weight copolymer of ethylene and at least one other comonomer has an acrylic acid and methacrylic acid combined comonomer content of at least 9 weight percent.

4. An ionomer/high density polyethylene blend of claim 1 further comprising for every one hundred parts by weight of ionomer/high density polyethylene blend from one to twenty parts by weight polyethylene modified with from 0.2 to 5.0 weight percent maleic anhydride comonomer.

5. A method of reducing the viscosity of an ionomer/high density polyethylene blend without significantly degrading impact resistance and tensile strength comprising the step of blending for every one hundred parts by weight of ionomer/high density polyethylene blend from one to twenty parts by weight low molecular weight copolymer of ethylene and at least one other comonomer selected from the group consisting of acrylic acid, methacrylic acid and mixtures thereof, wherein said low molecular weight copolymer has a melt index (ASTM D1238) of greater than 350 dg/min and an acrylic acid and methacrylic acid combined comonomer content of at least 5 weight percent.

6. A method of claim 5 wherein said low molecular weight copolymer of ethylene and at least one other comonomer has a melt index of at least 900 dg/min.

7. A method of claim 5 wherein said low molecular weight copolymer of ethylene and at least one other comonomer has an acrylic acid and methacrylic acid combined comonomer content of at least 9 weight percent.

8. A method of claim 5 further comprising the step of blending for every one hundred parts by weight of ionomer/high density polyethylene blend from one to twenty parts by weight polyethylene modified with from 0.2 to 5.0 weight percent maleic anhydride comonomer.