Plastic Living Hinges Using Block Composite Polymers

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Solution Overview

Problem

Plastic living hinges made from polypropylene exhibit poor low temperature impact strength, leading to breakage during handling, packaging, and shipping, while those made from high density polyethylene (HDPE) offer better impact strength but compromised durability.

Innovation Solution

A plastic living hinge blend comprising an ethylene-based polymer and a composite component selected from a block composite, crystalline block composite, or a combination thereof, which enhances both hinge durability and low temperature impact strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If polypropylene is used for plastic living hinges, then hinge durability is improved, but low temperature impact strength deteriorates

Engineering Contradiction:

Improvehinge durabilityVSAvoidlow temperature impact strength

Core Design Contradiction:

Duration of action of stationary objectVSStrength

Solution Approach 1:

The patent uses a composite material system consisting of HDPE as the base polymer combined with a block copolymer comprising polyethylene and polypropylene segments. This composite structure allows the hinge to exhibit both the durability characteristics of polypropylene and the low temperature impact strength of HDPE, resolving the contradiction between these two properties through material composition rather than single-material reliance

Inventive Principle:

Principle #40Composite materials

2Strength

If high density polyethylene (HDPE) is used for plastic living hinges, then low temperature impact strength is improved, but hinge durability deteriorates

Engineering Contradiction:

Improvelow temperature impact strengthVSAvoidhinge durability

Core Design Contradiction:

StrengthVSDuration of action of stationary object

Solution Approach 1:

The patent employs a block copolymer composite where HDPE provides the low temperature impact strength while polypropylene segments within the same material provide durability. This allows simultaneous achievement of both properties that were previously mutually exclusive when using pure HDPE

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If polypropylene is used for plastic living hinges, then ease of processing is improved, but low temperature impact strength deteriorates

Engineering Contradiction:

Improveease of processingVSAvoidlow temperature impact strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent modifies the material parameters by creating a block copolymer with specific molecular architecture (polyethylene and polypropylene blocks) that changes the physical properties of the material. This parameter change in material composition allows maintaining processability while significantly improving low temperature impact strength

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11261316B2Plastic living hinges with block composite polymer

Publication Date: 2022.03.01 DOW GLOBAL TECHNOLOGIES LLC

AI summary

The present disclosure provides a plastic living hinge. The plastic living hinge includes a blend containing (A) an ethylene-based polymer; and (B) a composite component selected from the group consisting of a block composite, a crystalline block composite, and a combination thereof.