Branched Polyester Coatings via Free Radical Polymerization

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Solution Overview

Problem

Conventional linear and branched polyester resins used in coatings have limitations such as low molecular weight, poor substrate adhesion, and difficulty in achieving a balance of chemical resistance and flexibility, due to their relatively low average functionality and molecular weight.

Innovation Solution

A coating composition comprising a branched polyester polymer prepared by free radical polymerization of the double bonds of an unsaturated polyester prepolymer, consisting of a hard segment, a polyol segment, and an unsaturated polycarboxylic acid or anhydride, which results in a high molecular weight and high functionality polyester with improved adhesion and resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the functionality of polyester resin is increased to improve adhesion and chemical resistance, then the molecular weight decreases, resulting in poor substrate adhesion and limited compatibility

Engineering Contradiction:

Improvesubstrate adhesionVSAvoidmolecular weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The polyester resin is segmented into distinct functional segments: flexible aliphatic segments (providing flexibility and high molecular weight) and rigid aromatic/cycloaliphatic segments (providing functionality, chemical resistance, and adhesion). This segmentation allows each segment to independently contribute its specific properties without compromising the overall molecular weight or adhesion characteristics.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention creates a composite polyester structure combining aliphatic polyol segments with aromatic/cycloaliphatic acid segments. This composite approach integrates the benefits of both aliphatic (flexibility, molecular weight) and aromatic (functionality, chemical resistance) components into a single resin system that achieves high functionality without sacrificing molecular weight or substrate adhesion.

Inventive Principle:

Principle #40Composite materials

2Strength

If high molecular weight polyester is used to achieve good flexibility and resistance to mechanical deformation, then the average functionality per chain decreases, limiting further use in coatings

Engineering Contradiction:

ImproveflexibilityVSAvoidfunctionality

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The polyester chain is segmented into flexible aliphatic portions (maintaining flexibility and molecular weight) and rigid aromatic/cycloaliphatic portions (increasing functionality). This segmentation enables the resin to simultaneously achieve high molecular weight for flexibility and high functionality for coating applications.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different segments of the polyester chain are assigned different local qualities: aliphatic segments provide flexibility and molecular weight, while aromatic/cycloaliphatic segments provide functionality and chemical resistance. This local differentiation allows the overall resin to exhibit both high flexibility and high functionality.

Inventive Principle:

Principle #3Local quality

3Reliability

If conventional linear polyester resins are used, then the coating exhibits poor chemical resistance and solvent resistance, but increasing functionality leads to lower molecular weight and poor substrate adhesion

Engineering Contradiction:

Improvechemical resistanceVSAvoidmolecular weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The invention creates a composite polyester structure integrating aliphatic polyol segments (providing flexibility and molecular weight) with aromatic/cycloaliphatic acid segments (providing chemical resistance and functionality). This composite structure achieves high chemical resistance without sacrificing molecular weight or substrate adhesion.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The polyester is segmented into chemically resistant aromatic/cycloaliphatic segments and flexible aliphatic segments. This segmentation allows the resin to simultaneously achieve high molecular weight for adhesion and high functionality for chemical resistance in coating applications.

Inventive Principle:

Principle #1Segmentation

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 solution achieves a high molecular weight and functionality, enabling coatings with enhanced flexibility, durability, and chemical resistance, suitable for various industrial applications including packaging, automotive, and coil coatings.

Implementation Method 1

a branched polyester polymer prepared by free radical polymerization of the double bonds of an unsaturated polyester polymer

Methodology Applied

Scientific EffectFree radical polymerization: Photopolymerisation

Data Source

PatentEP2552797B1Branched polyester polymers and coatings comprising the same

Publication Date: 2020.05.06 PPG INDUSTRIES OHIO INC

AI summary

A polyester prepared by free radical polymerization of an unsaturated polyester prepolymer, wherein the polymerization occurs primarily by reaction of the unsaturation is disclosed. Coatings comprising the same are also disclosed, as are substrates coated at least in part with such coatings.