Impact Copolymer Melt Flow Rate Matching for Haze Reduction

Solution Overview

Problem

Impact copolymers exhibit high haze and stress whitening, limiting their applications due to suboptimal optical properties while maintaining good impact strength and toughness.

Innovation Solution

The development of an impact copolymer with improved optical clarity is achieved by selecting a continuous phase polymer and a rubber phase polymeric material, ensuring a final melt flow rate within 2 g/10 min of the continuous phase, and adjusting the ethylene content and intrinsic viscosity of the rubber phase to match the viscosity of the continuous phase, thereby reducing haze and stress whitening.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If impact copolymer is used to provide good impact strength and toughness, then physical properties are improved, but optical properties deteriorate with high haze and stress whitening

Engineering Contradiction:

Improveimpact strengthVSAvoidhaze

Core Design Contradiction:

StrengthVSIllumination intensity

Solution Approach 1:

The patent applies parameter changes by carefully controlling the melt flow rate of the rubber phase polymeric material to be within 2 g/10 min of the continuous phase polymer, and adjusting the ethylene content and intrinsic viscosity of the rubber phase. These parameter optimizations reduce phase separation and improve optical clarity while maintaining impact strength and toughness.

Inventive Principle:

Principle #35Parameter changes

2Strength

If impact copolymer is used to provide good impact strength and toughness, then physical properties are improved, but optical properties deteriorate with stress whitening

Engineering Contradiction:

ImprovetoughnessVSAvoidstress whitening

Core Design Contradiction:

StrengthVSIllumination intensity

Solution Approach 1:

The patent applies parameter changes by carefully controlling the melt flow rate of the rubber phase polymeric material to be within 2 g/10 min of the continuous phase polymer, and adjusting the ethylene content and intrinsic viscosity of the rubber phase. These parameter optimizations reduce phase separation and improve optical clarity while maintaining impact strength and toughness.

Inventive Principle:

Principle #35Parameter changes

3Strength

If rubber phase polymeric material is added to improve impact properties, then physical properties are improved, but viscosity mismatch increases causing higher haze

Engineering Contradiction:

Improveimpact resistanceVSAvoidviscosity mismatch

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by carefully controlling the melt flow rate of the rubber phase polymeric material to be within 2 g/10 min of the continuous phase polymer, and adjusting the ethylene content and intrinsic viscosity of the rubber phase. These parameter optimizations reduce phase separation and improve optical clarity while maintaining impact strength and toughness.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies the copying principle by selecting a rubber phase polymeric material whose melt flow rate closely matches (within 2 g/10 min) that of the continuous phase polymer. This viscosity matching reduces interfacial tension and phase separation, thereby decreasing haze while maintaining impact properties.

Inventive Principle:

Principle #26Copying

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The approach results in impact copolymers with significantly lower haze and stress whitening, enhancing their optical properties without compromising physical properties such as impact strength, maintaining good toughness and stiffness at ambient temperatures while slightly reducing impact resistance at lower temperatures.

Implementation Method 1

selecting a rubber phase polymeric material having an intrinsic viscosity such that the viscosity of the rubber phase matches the viscosity of the continuous phase

Methodology Applied

Scientific EffectViscosity matching:

Implementation Method 2

selecting a rubber phase polymeric material such that the final melt flow rate of the impact copolymer is within 2 g/10 min of said first melt flow rate

Methodology Applied

Scientific EffectMelt flow rate matching:

Data Source

PatentUS9416238B2Method for the preparation of a heterophasic copolymer and uses thereof

Publication Date: 2016.08.16 FINA TECH INC

AI summary

Methods for preparing an impact copolymer by selecting a continuous phase polymer having a first melt flow rate and selecting a rubber phase polymeric material such that the final melt flow rate of the impact copolymer is within 2 g/10 min of the first melt flow rate. Impact copolymers made from such methods and films and molded articles produced from such impact copolymers are also included.