HASE Thickener Composition for VAE Coating Heat Stability

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Solution Overview

Problem

Vinyl acetate-ethylene copolymer (VAE) based paints using cellulosic thickeners like hydroxyethyl cellulose (HEC) face challenges with heat age stability, and synthetic thickeners like hydrophobically modified urethane polymers (HEUR) are expensive and difficult to match in rheological performance.

Innovation Solution

A composition comprising an aqueous dispersion of a vinyl acetate copolymer with a glass transition temperature (Tg) range of -10 °C to 50 °C, combined with a hydrophobically modified alkali soluble emulsion (HASE) containing specific weight percentages of ethyl acrylate, methacrylic acid, acrylic acid, and hydrophobic macromolecular groups, providing a stable thickening solution for VAE based coatings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If HEC thickeners are used in VAE based paints, then desirable rheological profile is achieved, but heat age stability is poor resulting in gel formation

Engineering Contradiction:

Improverheological profileVSAvoidheat age stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the thickener by using HASE polymers with specific monomer ratios (ethyl acrylate 45-60%, methacrylic acid 30-45%, acrylic acid 2-20%, and hydrophobic macromolecular groups 0.1-10%). This parameter change allows the thickener to provide both desirable rheological properties and heat age stability, resolving the contradiction between ease of operation and reliability.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If HEUR rheology modifiers are used, then cost is reduced compared to HEC, but rheological performance matching is difficult

Engineering Contradiction:

ImprovecostVSAvoidrheological performance

Core Design Contradiction:

Quantity of substanceVSEase of operation

Solution Approach 1:

The patent employs HASE polymers that combine hydrophobic macromolecular groups with polyacid chains, creating a composite structure that enables both cost-effectiveness and desirable rheological performance. The composite nature of HASE allows it to thicken VAE paints effectively while maintaining heat age stability, addressing both cost and performance requirements.

Inventive Principle:

Principle #40Composite materials

3Quantity of substance

If DR-110 HASE thickener is used, then cost is reduced and rheological profile is improved, but heat age stability deteriorates causing gelation

Engineering Contradiction:

ImprovecostVSAvoidheat age stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent modifies the compositional parameters of HASE by specifying precise ranges for each monomer component, particularly the inclusion of 2-20% acrylic acid and 0.1-10% hydrophobic macromolecular groups. These parameter adjustments optimize the balance between cost, rheological performance, and heat age stability, preventing gelation while maintaining affordability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses HASE as a composite material combining hydrophobic macromolecular groups with polyacid chains, which provides both cost-effectiveness and heat age stability. The composite structure enables the thickener to resist gelation during heat aging while maintaining desirable rheological properties at low cost.

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 HASE thickened VAE based coating composition exhibits excellent heat-aged stability with minimal gel formation, outperforming traditional HEC thickeners and offering a cost-effective alternative.

Implementation Method 1

hydrophobically modified alkali soluble emulsion (HASE) comprising... iv) from 0.1 to 10 weight percent hydrophobic macromolecular groups

Methodology Applied

Scientific EffectHydrophobic association: Hydrophobe

Implementation Method 2

presumably because HECs thicken paints by way of a volume exclusion mechanism

Methodology Applied

Scientific EffectVolume exclusion:

Implementation Method 3

a vinyl acetate copolymer having a T g in the range of -10 °C to 50 °C

Methodology Applied

Scientific EffectPolymer entanglement:

Implementation Method 4

vinyl acetate-ethylene copolymer (VAE) based binders

Methodology Applied

Scientific EffectIntermolecular forces: Van der Waals Force

Implementation Method 5

Cellulosic thickeners also impart heat age stability to such paints, resulting in stable viscosities after exposure to elevated temperature conditions

Methodology Applied

Scientific EffectThermal stability:

Implementation Method 6

DR-110 thickened VAE based paints tend to be unstable and gel upon heat aging

Methodology Applied

Scientific EffectPhase separation suppression:

Data Source

PatentEP2853570B1Composition comprising an emulsion of VAE-copolymer and a HASE rheology modifier

Publication Date: 2016.06.08 ROHM & HAAS CO

AI summary

The present invention relates to a composition comprising a vinyl acetate copolymer and a HASE thickener comprising structural units of ethyl acrylate, methacrylic acid, acrylic acid, and a hydrophobic macromonomer. The composition of the present invention shows an improvement in heat aged stability over a vinyl acetate copolymer based paint thickened with a HASE that does not include structural units of acrylic acid.