Aqueous Wood Coating Composition for Anti-Grain Raising
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Solution Overview
Problem
Waterborne coatings in the wood finishing industry suffer from grain raising, leading to surface wrinkles and roughness due to varying swelling properties of wood fibers, and two-component polyurethane coatings have handling issues and shorter pot life.
Innovation Solution
Aqueous coating composition combining a specific oligomer and film-forming polymer with beads, optimized for anti-grain raising performance and good sandability, comprising certain structural units and particle sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If waterborne coating compositions are used, then VOC emissions are reduced, but grain raising occurs leading to surface wrinkles and roughness
Solution Approach 1:
The patent modifies the chemical composition parameters of the waterborne coating by incorporating specific oligomers with controlled molecular weights (1,000-9,500 g/mol) and specific monomer ratios (30-99% hydrophilic monoethylenically unsaturated nonionic monomer, 0-30% hydrophobic monoethylenically unsaturated nonionic monomer, 0-20% functional monomer). This parameter optimization allows the coating to suppress grain raising while maintaining low VOC emissions.
Solution Approach 2:
The patent creates a composite aqueous coating composition combining multiple components: film-forming polymer (12.5-87% by weight), specific oligomer (9.5-85% by weight based on film-forming polymer weight), and beads (2.5-50% by weight based on film-forming polymer weight). This composite formulation achieves both anti-grain raising performance and environmental benefits.
2Manufacturing precision
If two-component waterborne polyurethane coating compositions are used, then anti-grain raising performance is improved, but pot life is shortened and handling becomes more complicated
Solution Approach 1:
The patent merges multiple functional components into a single-component aqueous coating composition. The film-forming polymer, oligomer with specific molecular weight and monomer composition, and beads are combined in one formulation that provides anti-grain raising performance without requiring separate components, thereby simplifying handling and extending pot life.
Solution Approach 2:
The single-component aqueous coating composition performs multiple functions simultaneously: it provides film formation, suppresses grain raising, and maintains good sandability. The oligomer with specific structural units (hydrophilic and hydrophobic monoethylenically unsaturated nonionic monomers plus functional monomers) enables this multi-functionality in one formulation.
3Strength
If water is absorbed by wood fibers, then coating adhesion is improved, but fibers swell and shrink causing wrinkles and roughness
Solution Approach 1:
The patent applies preliminary anti-action by incorporating the specific oligomer with hydrophilic and hydrophobic monomer units that preemptively counteracts the swelling effect of wood fibers. The oligomer's molecular structure (with 30-99% hydrophilic and 0-30% hydrophobic monoethylenically unsaturated nonionic monomer) creates a protective effect that prevents grain raising before it occurs, while still allowing necessary water absorption for adhesion.
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 provides coatings with anti-grain raising performance of 4 or more and good sandability of 3 or more, addressing the grain raising issue and improving surface finish quality.
Implementation Method 1
a film-forming polymer; (b) an oligomer having a number average molecular weight of 9,500 g/mol or less, wherein the oligomer comprises structural units of acid monomer, salt thereof, hydrophilic monoethylenically unsaturated nonionic monomer, hydrophobic monoethylenically unsaturated nonionic monomer, and monoethylenically unsaturated functional monomer
Implementation Method 2
beads with a mean particle size of from 5.0 to 10.5 μm
Data Source
AI summary
An aqueous coating composition comprising (a) from 12.5% to 87% by weight based on the weight of the aqueous coating composition, of a film-forming polymer; (b) from 9.5% to 85% by weight based on the weight of the film-forming polymer, of a specific oligomer; and (c) from 2.5% to 50% by weight based on the weight of the film-forming polymer, of beads with a mean particle size of from 5.0 to 10.5 μm; and a process for preparing the aqueous coating composition.