Acrylic Coating Composition for Wood Knot Bleeding Sealing

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Solution Overview

Problem

Wood knot bleeding, where resinous extractives from knots in wood migrate to the surface, causing unsightly stains, is difficult to control, especially in mass-produced kiln-dried timber, leading to ongoing issues in painted applications like indoor panels and furniture.

Innovation Solution

An aqueous acrylic-based coating composition containing 0.2-1% zirconium compounds and suitable acrylic binders, optionally enhanced with lamellar inorganic fillers like perlite or mica, is applied to seal wood knots, preventing bleeding and providing a stable, one-component water-based solution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional knot primer paint or solution is applied during preparation, then some bleeding control is achieved, but complete bleeding control is difficult to achieve especially in mass-produced kiln-dried timber

Engineering Contradiction:
Improvebleeding control effectivenessVSAvoidcontrol consistency
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the sealing agent by incorporating specific compounds (zinc phosphate, zinc silicate, or zinc hydroxide) in optimized concentrations (0.1-5% by weight) combined with acrylic binders. This parameter optimization enables complete bleeding control while maintaining consistency across mass-produced timber, resolving the contradiction between reliability and manufacturing precision.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite sealing material combining inorganic zinc compounds with organic acrylic binders and optional fillers. This composite formulation synergistically provides both the sealing effectiveness needed for reliability and the formulation consistency required for manufacturing precision in mass-produced timber.

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If a one-component water-based composition is used for treating wood, then ease of application and storage is improved, but achieving effective sealing performance becomes more challenging

Engineering Contradiction:
Improveapplication and storage convenienceVSAvoidsealing performance
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent merges multiple functional components (sealing agents, binders, and optional fillers) into a single integrated water-based composition. This unified formulation maintains ease of application and storage while achieving effective sealing performance through the synergistic interaction of zinc compounds, acrylic binders, and filler materials.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The one-component composition is designed to perform multiple functions simultaneously: it seals knots, prevents bleeding, and provides a stable base for subsequent coatings. The formulation universally applies to various wood types and conditions, maintaining both operational ease and sealing reliability across different applications.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If zirconium compounds are used to enhance sealing effect, then bleeding prevention is improved, but viscosity increase during storage occurs

Engineering Contradiction:
Improvesealing effectVSAvoidviscosity stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent optimizes the concentration parameter of zirconium compounds to a specific range (0.2-1% by weight) and combines them with acrylic binders and lamellar fillers. This parameter optimization maintains effective sealing while preventing excessive viscosity increase, ensuring storage stability alongside sealing reliability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite system where zirconium compounds work synergistically with acrylic binders and lamellar inorganic fillers. This composite formulation provides the necessary sealing effect while the combined system maintains acceptable viscosity and storage stability, resolving the contradiction between sealing performance and composition stability.

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 composition effectively prevents wood knot bleeding, showing improved performance in accelerated weathering tests with slower yellowing and maintaining stability over time, suitable for industrial-scale use without viscosity issues or pH-related corrosion concerns.

Implementation Method 1

The zirconium compound used in the composition together with suitable acrylic binders provides a sealing effect

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 2

aqueous acrylic-based coating composition comprising one or more acrylic (co)polymer(s)

Methodology Applied
Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentEP3845586A1Acrylic-based coating composition, use thereof as wood knot bleeding sealer, and method for sealing wood knot bleeding
Publication Date: 2021.07.07 PPG INDUSTRIES OHIO INC
  • EP3845586A1 patent drawingFigure 1~2
  • EP3845586A1 patent drawingFigure 3~4
  • EP3845586A1 patent drawingFigure 5~6

AI summary

The present application relates to an aqueous acrylic-based coating composition comprising one or more acrylic (co)polymer(s), and 0.2-1% (w/w) of zirconium compound, and to use thereof as a knot bleeding sealer in wood treatment. The present application also relates to a method for sealing knot bleeding in wood treatment, and to wood obtained with the method.