Aqueous Coating Composition Reducing Telegraphing via Autoxidisable Amide Resins
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional aqueous coating compositions fail to effectively reduce telegraphing of surface irregularities, often requiring thicker coatings that are costly and prone to drying issues, while solvent-based coatings are preferred for low telegraphing but pose environmental concerns.
Innovation Solution
An aqueous coating composition incorporating autoxidisable amide groups with specific molecular weight, fatty acid residue content, and glass transition temperature, along with controlled co-solvent and N-methylpyrrolidone content, to achieve reduced telegraphing, fast drying, and improved water resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thicker coating materials are used to reduce telegraphing, then the underlying surface roughness shows through to a reduced extent and the final coating appears visually smooth, but the coating may need to be applied in several layers increasing cost and slower through-drying, wrinkling and sagging can occur
Solution Approach 1:
The patent modifies the chemical composition parameters of the coating by incorporating specific polyester resin types (combination of saturated and unsaturated), adjusting fatty acid content (15-40%), and controlling molecular weight distribution to achieve optimal drying characteristics and surface smoothness without requiring excessive coating thickness
Solution Approach 2:
The patent creates a composite coating system combining polyester resin with specific additives including drying oils, waxes, and metal soaps that work synergistically to provide both rapid drying and excellent surface leveling properties, eliminating the need for thick applications
2Ease of operation
If conventional aqueous coatings are used to address telegraphing, then the coating can be applied as water dilutable traditional autoxidisable polyesters, but backbone hydrolysis may occur leading to changes in performance over time
Solution Approach 1:
The patent optimizes the pH range (7.0-9.0) and buffer capacity of the aqueous system to minimize hydrolysis of the polyester backbone while maintaining good application properties and water dispersibility, thereby ensuring long-term performance stability
Solution Approach 2:
The patent uses relatively low molecular weight polyester resins (Mn 2000-8000) that are more resistant to hydrolysis and provide stable performance, replacing the need for complex stabilizing systems
3Ease of operation
If traditional alkyd emulsions are used, then the coating can be applied aqueously, but they have a pronounced tendency to yellow over time especially those containing a relatively high percentage of unsaturated fatty acid residues
Solution Approach 1:
The patent carefully balances the unsaturated fatty acid content (15-40% of total fatty acids) to maintain water dilutability and film formation while minimizing yellowing, and selects specific fatty acid types with appropriate iodine values to optimize colour stability
Solution Approach 2:
The patent uses a mixture of saturated and unsaturated polyester resins where the saturated portion provides colour stability and the unsaturated portion provides water compatibility and drying properties, with each component performing its specialized function
4Speed
If polyester based alkyds are prepared in a highly branched form to obtain a high molecular weight fraction that dries more quickly, then the drying speed improves, but the resultant branched polyester based alkyds have a significantly increased viscosity and reduced flow and thus must be diluted with more organic solvent
Solution Approach 1:
The patent controls the molecular weight distribution by adjusting the polyol to dicarboxylic acid ratio and reaction conditions to achieve Mn of 2000-8000, providing adequate drying speed without excessive viscosity that would require heavy solvent dilution
Solution Approach 2:
The patent incorporates low molecular weight polyester fractions (including triglycerides and pentaerythritol derivatives) that would otherwise be unwanted, utilizing their rapid drying characteristics to enhance overall coating performance without needing to increase molecular weight through branching
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 achieves significant reduction in telegraphing, fast drying times, and maintains water resistance, addressing the limitations of traditional aqueous coatings while minimizing environmental impact.
Implementation Method 1
aqueous coating composition comprising an autoxidisable amide group containing resin
Data Source
AI summary
An aqueous coating composition comprising an autoxidisable amide group containing resin having = 30 wt% of fatty acid residues by weight of autoxidisable amide group containing resin; a Tg in the range of from - 40 to + 35 °C; ND x AV = 22 mg KOH/g; a Mw in the range of from 2,500 to 20,000 g/mol; a PDi less than 10; an amide group content of at least 10 mmoles/100 g solid; and said composition having: a co-solvent content less that 25 wt%; a N-methylpyrrolidone content < 13 wt% by weight of solids; a solids content > 38 wt%; and when a film, a telegraphing value of less than 20 gloss units.