Foamed Coating Composition for Vertical Surface Application
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Solution Overview
Problem
Aqueous coating compositions with low resin and solids content, commonly used for exterior wood surfaces, face challenges in application due to low viscosity, leading to dripping and overspray, especially when applied to vertical surfaces, resulting in an unacceptable appearance and visible gas bubbles in the dried coating.
Innovation Solution
A method involving a liquid aqueous coating composition with carefully chosen resin, surfactant, coalescence solvent, and thickener concentrations, foamed to create a stable foam that can be applied on vertical surfaces without sagging or dripping, allowing gas escape and drying to form a homogeneous, bubble-free coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If low resin and solids content coating composition is used, then can stability and ease of application is improved, but viscosity is too low causing dripping and overspray
Solution Approach 1:
The patent changes the physical state of the coating composition from liquid to foam by controlling foam stability parameters. The foam structure provides sufficient viscosity to prevent dripping and overspray while maintaining the low resin and solids content formulation, thus resolving the contradiction between ease of application and harmful application defects.
Solution Approach 2:
The patent utilizes phase transition from liquid coating composition to foamed coating composition. The foam phase provides the necessary viscosity and structural integrity to prevent dripping and overspray during application, while the low resin and solids content is maintained in the foam structure, solving the contradiction between operational ease and application quality.
2Area of stationary object
If liquid coating composition is applied to vertical surfaces, then coverage is achieved, but sagging and dripping occurs due to low viscosity
Solution Approach 1:
The patent applies the coating composition in foamed form rather than liquid form. The foam structure provides sufficient viscosity and structural support to prevent sagging and dripping on vertical surfaces, while still achieving complete coverage. The foam collapses during drying to form a uniform coating, resolving the contradiction between coverage and coating uniformity.
Solution Approach 2:
The patent performs foaming of the coating composition before application to vertical surfaces. This preliminary action creates a stable foam structure that prevents sagging and dripping during the critical drying period, ensuring uniform coating formation on vertical surfaces while maintaining adequate coverage.
3Shape
If foam application is used, then sagging and dripping is reduced, but visible gas bubbles appear in dried coating
Solution Approach 1:
The patent optimizes foam stability parameters and drying conditions to control the collapse timing of foam bubbles. By adjusting these parameters, the foam collapses completely during the drying process, eliminating visible gas bubbles in the final coating while maintaining the coating uniformity benefits of foam application.
Solution Approach 2:
The patent ensures continuous foam stability during application and controlled collapse during drying. This continuous process management allows the foam to maintain its protective function during application, then smoothly transition to complete bubble collapse during drying, achieving both coating uniformity and acceptable appearance without visible bubbles.
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 method enables convenient application of low-viscosity coating compositions on vertical surfaces, resulting in a dried coating with an acceptable appearance and reduced sagging or dripping, achieving a stable and aesthetically pleasing finish.
Implementation Method 1
Aqueous coating compositions are typically applied to substrates as a liquid by brush or by roller or as an aerosol by spray. For low viscosity coating compositions, brush or roller application typically results in dripping of the coating composition from the applicator (brush or roller) or from the substrate.
Implementation Method 2
providing a liquid aqueous coating composition, the composition comprising an acrylic resin as binder, one or more surfactants, a coalescence solvent, and a thickener
Implementation Method 3
Thickeners are generally used to maintain can stability, i.e. to keep any inorganic particulate ingredients such as pigments and extenders, in suspension. The viscosity of such low resin, low solids coating compositions, also with thickeners, is usually below 0.5 Pa.s
Implementation Method 4
allowing gas to escape from the layer of foamed coating composition and allowing the coating composition to dry to form a homogeneous non-foam dried coating
Data Source
AI summary
The invention relates to a method for coating a substrate comprising: a) providing a liquid aqueous coating composition, the composition comprising an acrylic resin as binder, one or more surfactants, a coalescence solvent, and a thickener; b) foaming the liquid aqueous coating composition to obtain a foamed coating composition; c) applying a layer of the foamed coating composition on the substrate; and d) allowing gas to escape from the layer of foamed coating composition and allowing the coating composition to dry to form a homogeneous non-foam dried coating, wherein the liquid aqueous coating composition provided in step a) comprises the acrylic resin in a concentration in the range of from 1 to 20 wt%, comprises the thickener in a concentration in the range of from 0.05 to 2.0 wt%, and has a solids content of at most 25 wt%, based on the total weight of the liquid aqueous coating composition. The invention further relates to foamed aqueous coating composition obtainable by steps a) and b).