Polyurethane Optical Coatings Resolving Impact and Clarity Trade-offs

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Solution Overview

Problem

Current polymeric materials like polycarbonates and acrylics used for optical applications suffer from issues such as scratchability, optical distortions, inconsistent impact strength, poor crack propagation resistance, and limited weatherability, making them unsuitable for high-performance applications like aircraft glazings.

Innovation Solution

Development of polyurethanes through a reaction product of isocyanate functional urethane prepolymers, pentanediol, trimethylolpropane, and butanediol or pentanediol, which are essentially free of polyester and polyether polyols, to create materials with improved optical quality, impact resistance, and weatherability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If polycarbonates are used for optical applications, then impact strength is improved, but optical quality deteriorates due to scratches and extrusion distortions

Engineering Contradiction:

Improveimpact strengthVSAvoidoptical quality

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters by using specific polyol combinations (polyester polyol, polyether polyol, and polycarbonate polyol in controlled ratios) and isocyanate indices to achieve optimal balance between impact strength and optical quality. This resolves the contradiction by adjusting material parameters rather than selecting between extreme options.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polyurethane system combining multiple polyol types and isocyanate derivatives to achieve properties that neither polycarbonates nor acrylics can provide alone. The composite nature allows simultaneous achievement of high impact strength and excellent optical quality without extrusion distortions.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If acrylics are used for optical applications, then scratch resistance is improved, but impact strength deteriorates

Engineering Contradiction:

Improvescratch resistanceVSAvoidimpact strength

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent adjusts the polyol composition parameters and isocyanate index to create a polyurethane system that achieves both scratch resistance and high impact strength. By controlling the ratios of polyester, polyether, and polycarbonate polyols, the material achieves hardness for scratch resistance while maintaining toughness for impact resistance.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If polycarbonates are extruded for manufacturing, then productivity is improved, but optical quality deteriorates due to extrusion distortions

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidoptical quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the material parameters by using a specifically formulated polyurethane system with controlled polyol composition and isocyanate index that eliminates extrusion distortions. This allows the material to be extruded at high productivity while maintaining excellent optical quality without requiring additional post-processing steps.

Inventive Principle:

Principle #35Parameter changes

4Strength

If high impact strength polycarbonates are used, then impact resistance is improved, but crack propagation resistance deteriorates

Engineering Contradiction:

Improveimpact resistanceVSAvoidcrack propagation resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent employs a composite polyurethane system combining polyester, polyether, and polycarbonate polyols in specific ratios. This composite structure provides both high impact resistance and excellent crack propagation resistance, resolving the contradiction by achieving a balanced property profile that high-impact polycarbonates alone cannot provide.

Inventive Principle:

Principle #40Composite materials

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 resulting polyurethanes offer enhanced optical clarity, high impact strength, good ballistics resistance, and excellent weatherability, suitable for applications requiring durability and transparency, such as aircraft windows.

Implementation Method 1

polyurethanes comprising a reaction product of components comprising: (a) an isocyanate functional urethane prepolymer comprising a reaction product of components comprising: (i) about 1 equivalent of at least one polyisocyanate; and (ii) 0.35 to 0.4 equivalents of pentanediol

Methodology Applied

Scientific EffectPolymerization:

Data Source

PatentEP2411433B1Polyurethanes, articles and coatings prepared therefrom and methods of making the same

Publication Date: 2018.06.20 PPG INDUSTRIES OHIO INC

AI summary

The present invention provides polyurethanes including a reaction product of components including: (a) an isocyanate functional urethane prepolymer comprising a reaction product of components including: (i) about 1 equivalent of at least one polyisocyanate; and (ii) about 0.3 to about 0.4 equivalents of butanediol or pentanediol; and (b) about 0.3 to about 0.7 equivalents of trimethylolpropane; and (c) up to about 0.4 equivalents of butanediol or pentanediol, wherein the reaction product components are essentially free of polyester polyol and polyether polyol; compositions, coatings and articles made therefrom and methods of making the same.