Autoxidisable Polyester Coating Reduces Telegraphing
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Solution Overview
Problem
Conventional aqueous coating compositions face issues such as telegraphing of surface irregularities, hydrolysis, cissing, yellowing, and slow drying, which affect the appearance and durability of coatings, especially when applied to substrates with visual irregularities.
Innovation Solution
An aqueous coating composition comprising an autoxidisable fatty acid modified polyester resin with specific properties, including high fatty acid residue content, controlled molecular weight, and low unsaturated fatty acid levels, which crosslinks in the presence of air, reducing telegraphing and improving drying times while maintaining hydrolytic stability and color retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thicker coating materials are used to reduce telegraphing, then surface smoothness is improved, but drying time increases and sagging occurs
Solution Approach 1:
The patent modifies the chemical composition parameters of the coating by incorporating specific polyester resins with controlled molecular weights and fatty acid contents, enabling the coating to achieve smooth surface appearance at thinner applications without the negative effects of thick coatings
Solution Approach 2:
The patent creates a composite coating system combining polyester resins, fatty acid modifiers, and specific additives that work together to provide both smooth surface appearance and rapid drying, resolving the contradiction between surface quality and drying speed
2Manufacturing precision
If traditional water dilutable autoxidisable alkyds are used, then telegraphing is reduced, but backbone hydrolysis occurs leading to performance degradation
Solution Approach 1:
The patent changes the chemical structure parameters by using modified polyester resins with specific molecular weights and fatty acid contents, and controls the pH and acid value parameters to prevent hydrolysis while maintaining smooth surface appearance
Solution Approach 2:
The patent replaces the traditional alkyd backbone (prone to hydrolysis) with more stable polyester resin structures that resist hydrolytic degradation, sacrificing some traditional alkyd properties for improved long-term stability
3Manufacturing precision
If traditional alkyd emulsions are used, then telegraphing is reduced, but cissing occurs when applied as over-coat
Solution Approach 1:
The patent adjusts the surface tension and viscosity parameters of the coating by selecting specific polyester resin structures and fatty acid modifiers, preventing cissing while maintaining the ability to reduce telegraphing effects
Solution Approach 2:
The patent uses specific polyester resin structures as intermediaries that bridge the gap between good flow properties (for telegraphing reduction) and good adhesion properties (for preventing cissing), enabling both functions to coexist
4Productivity
If high percentage of unsaturated fatty acid residues are used, then autoxidation drying is improved, but yellowing occurs over time
Solution Approach 1:
The patent optimizes the fatty acid composition parameters by selecting specific saturated and unsaturated fatty acid ratios, and choosing polyester resin structures that enable adequate drying speed while minimizing yellowing tendency
Solution Approach 2:
The patent applies different fatty acid modifications at different positions in the polyester structure, using unsaturated fatty acids primarily for drying functionality while using saturated fatty acids to maintain color stability in the final coating
5Productivity
If polyester based alkyds are highly branched to increase molecular weight, then drying speed is improved, but viscosity increases and flow is reduced
Solution Approach 1:
The patent controls the molecular weight and branching parameters of the polyester resin to achieve adequate drying speed while maintaining manageable viscosity levels through careful selection of resin synthesis parameters
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 reduces telegraphing, achieves fast drying, and maintains a smooth appearance over time, with improved hydrolytic stability and resistance to yellowing, resulting in a high-quality coating that is tack-free and water-resistant.
Implementation Method 1
an autoxidisable component and processes for making such compositions... crosslinks in the presence of air
Data Source
AI summary
An aqueous coating composition comprising an autoxidisable fatty acid modified polyester resin having = 40 wt% of fatty acid residues; a Tg in the range of from - 70 to + 20 °C; an acid value less than 40 mg KOH/g; a Mw in the range of from 5,000 to 125,000 g/mol; > 5 wt% of ring structures; and said composition having a co-solvent content less than 20 wt% by weight of solids; a solids content > 38 wt%; and when in the form of the film having a telegraphing value of less than 35 gloss units.