Aqueous Coating Composition with Alkali-Soluble Acrylic Polymer

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Solution Overview

Problem

Aqueous coating compositions with inorganic solid particles face challenges in achieving improved brush and roller application properties, particularly open time and leveling, at both high and moderate solid contents, while maintaining sufficient hardness and water-resistance.

Innovation Solution

An aqueous coating composition combining a dispersed acrylate binder polymer, an alkali-soluble acrylic polymer with a weight-averaged molecular weight of at most 200,000 g/mole, and a dispersed oxidatively drying resin, where the weight content of the oxidatively drying resin is lower than the alkali-soluble acrylic polymer, and the acrylate binder polymer content is higher, with a solid content ranging from 28 to 55 wt% and inorganic solid particles from 8 to 40 wt%, optimizing application properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the solid content of the coating composition is increased to improve hardness and water-resistance, then the application properties (open time and leveling) deteriorate

Engineering Contradiction:
ImprovehardnessVSAvoidapplication properties
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The invention changes the chemical composition parameters by introducing an alkali-soluble acrylic polymer with specific molecular weight (at most 200,000 g/mole) and acid value (20-150 mg KOH/g), and establishes specific weight ratio relationships between polymer components. This allows the coating to maintain good application properties at moderate solid contents (28-55 wt%) while achieving sufficient hardness and water-resistance, resolving the contradiction between solid content and application performance.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If the content of inorganic solid particles is increased to improve opacity and coverage, then the brush and roller application properties deteriorate

Engineering Contradiction:
Improveinorganic solid particles contentVSAvoidbrush and roller application properties
Core Design Contradiction:
Quantity of substanceVSEase of operation

Solution Approach 1:

The invention creates a composite binder system combining dispersed acrylate binder polymer, alkali-soluble acrylic polymer, and dispersed oxidatively drying resin. This composite polymer matrix effectively disperses and binds inorganic solid particles (8-40 wt%), maintaining good brush and roller application properties even at higher inorganic content, while achieving sufficient opacity and coverage.

Inventive Principle:
Principle #40Composite materials

3Reliability

If the weight content of oxidatively drying resin is increased to improve water-resistance, then the open time and leveling properties deteriorate

Engineering Contradiction:
Improvewater-resistanceVSAvoidopen time
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The invention establishes a specific weight ratio relationship where the oxidatively drying resin content is lower than the alkali-soluble acrylic polymer content. This parameter optimization allows the coating to achieve adequate water-resistance through the synergistic effect of the composite polymer system while maintaining sufficient open time and leveling properties during application.

Inventive Principle:
Principle #35Parameter changes

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 composition exhibits enhanced brush and roller application properties, acceptable hardness, and water-resistance, with improved open time and leveling, even at moderate solid contents, ensuring effective performance in paints with inorganic solid particles.

Implementation Method 1

an alkali-soluble acrylic polymer with a weight averaged molecular weight of at most 200,000 g/mole and an acid value in the range of from 20 to 150 mg KOH/g polymer

Methodology Applied
Scientific EffectDissolution: Solvation

Implementation Method 2

a dispersed oxidatively drying resin

Methodology Applied
Scientific EffectOxidation: Oxidation

Data Source

PatentEP3484968B1Aqueous coating composition
Publication Date: 2020.08.19 AKZO NOBEL COATINGS INT BV

AI summary

The invention relates to an aqueous coating composition comprising a dispersed acrylate binder polymer, an alkali-soluble acrylic polymer with a weight averaged molecular weight of at most 200,000 g/mole and an acid value in the range of from 20 to 150 mg KOH/g polymer, and optionally a dispersed oxidatively drying resin, wherein the weight content of the oxidatively drying resin, if present, is lower than the weight content of the alkali-soluble acrylic polymer and wherein the weight content of the acrylate binder polymer is higher than the weight content of the alkali-soluble acrylic polymer, wherein the solid content of the coating composition is in the range of from 28 to 55 wt %, and the content of inorganic solid particles is in the range of from 8 to 40 wt %, based on the total weight of the coating composition.