Waterborne Anionic Polymer Composition for Wood Knot Sealing

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Solution Overview

Problem

Existing wood coatings suffer from knot bleeding, which causes discoloration due to the migration of organic extractives from wood knots, and current solutions using inorganic chelating metals or epoxy binders are not environmentally friendly and pose health risks, while cationic polymers cause formulation difficulties.

Innovation Solution

A water-based anionic emulsion polymer with a star-like structure is produced through radical emulsion polymerization, featuring a core and a swellable/soluble outer layer that prevents knot bleeding by swelling or dissolving under specific conditions, without using solvents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If inorganic chelating metals or epoxy binders are used to block color change and prevent knot-bleeding, then knot-sealing capability is improved, but environmental friendliness deteriorates and health risks increase

Engineering Contradiction:

Improveknot-sealing capabilityVSAvoidenvironmental friendliness and health risks

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the chemical composition parameters by using water-based anionic emulsion polymer instead of solvent-based systems with inorganic metals or epoxy binders. The polymer contains carboxylic acid groups that provide chelating capability without requiring toxic heavy metals, thus maintaining knot-sealing effectiveness while improving environmental compatibility and safety

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces expensive and potentially hazardous inorganic chelating metals with an organic polymer system based on carboxylic acid-containing monomers. This polymer provides the necessary chelating function through its molecular structure without requiring toxic metal ions, eliminating health risks while maintaining effectiveness

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If cationic polymers are used to prevent knot-bleeding, then knot-sealing capability is improved, but formulation compatibility deteriorates

Engineering Contradiction:

Improveknot-sealing capabilityVSAvoidformulation compatibility

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of using cationic polymers that cause formulation difficulties, the invention inverts the approach by using anionic emulsion polymer. This anionic polymer is inherently compatible with standard anionic surfactants and additives used in water-based coating formulations, eliminating the formulation compatibility issues while maintaining effective knot-sealing performance

Inventive Principle:

Principle #13The other way round (Inversion)

3Object-affected harmful factors

If conventional emulsion polymerization is used to produce water-based coatings, then environmental friendliness is improved, but knot-sealing capability deteriorates

Engineering Contradiction:

Improveenvironmental friendlinessVSAvoidknot-sealing capability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The invention creates a composite polymer structure by copolymerizing carboxylic acid-containing monomers with other compatible monomers. This composite approach allows the polymer to simultaneously exhibit water-based environmental benefits and acquire knot-sealing functionality through the chelating carboxylic acid groups integrated into the polymer chain

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention modifies the chemical parameters of conventional emulsion polymer by incorporating specific carboxylic acid-containing monomers (such as acrylic acid, methacrylic acid, or itaconic acid) at controlled concentrations. This parameter change transforms the polymer's functionality to include chelating capability, enabling it to prevent extractive bleeding while maintaining the environmental advantages of water-based formulation

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 emulsion polymer effectively seals wood knots, preventing discoloration and migration of extractives, while being environmentally friendly and compatible with anionic formulations, offering improved knot-sealing and adhesion properties.

Implementation Method 1

featuring a core and a swellable/soluble outer layer that prevents knot bleeding by swelling or dissolving under specific conditions

Methodology Applied

Scientific EffectSwelling:

Implementation Method 2

featuring a core and a swellable/soluble outer layer that prevents knot bleeding by swelling or dissolving under specific conditions

Methodology Applied

Scientific EffectDissolution:

Implementation Method 3

A water-based anionic emulsion polymer with a star-like structure is produced through radical emulsion polymerization

Methodology Applied

Scientific EffectRadical polymerization:

Data Source

PatentEP4490210B1Waterborne polymer composition for wood applications

Publication Date: 2025.09.10 ORGANIK KIMYA SANAYI VE TIC AS

Figure 1

AI summary

The present invention relates to a multistage radical emulsion polymerization process for producing a knot sealing polymer dispersion of discrete particles dispersed in water, a polymer dispersion of discrete particles dispersed in water obtained by said process, and the use of said polymer dispersion as an indoor and outdoor coating composition for wood substrates or any wood-based material in order to prevent knot bleeding.