NIR Thermal Drying for Aqueous Resin Coatings
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Solution Overview
Problem
Conventional drying methods for aqueous resin coatings on wood-based panels result in uneven drying due to the insulating effect of the panels, leading to moisture gradients and flow disturbances in the resin layer, which are difficult to control and affect the quality of the finished product.
Innovation Solution
A method combining Near-Infrared (NIR) radiation irradiation and subsequent thermal treatment to dry the aqueous resin coatings, ensuring uniform drying across the entire coating cross-section and reducing residual moisture, thereby avoiding moisture gradients and improving the flow characteristics of the resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional hot air drying is used on wood-based panels, then the drying process is simple to implement, but the insulating effect of the panels causes uneven drying and moisture gradients in the resin layer
Solution Approach 1:
The patent combines two drying methods - hot air drying and infrared radiation drying - into a hybrid system. The infrared radiation penetrates the wood-based panel to provide internal heating, while hot air provides external drying, thereby eliminating the moisture gradients caused by the panel's insulating effect and achieving uniform drying throughout the resin layer.
Solution Approach 2:
The patent introduces infrared radiation as an additional drying dimension that penetrates through the panel thickness. This adds a through-thickness heating component to the conventional surface-level hot air drying, enabling simultaneous drying from both external and internal dimensions to eliminate moisture gradients.
2Use of energy by moving object
If hot air drying is used, then energy consumption is moderate, but flow disturbances occur in the resin layer affecting product quality
Solution Approach 1:
The patent merges hot air drying with infrared radiation drying to achieve more uniform moisture removal. This combination prevents the localized overheating and rapid surface drying that cause resin flow disturbances, thereby improving product quality while maintaining reasonable energy consumption through the efficient penetrative heating of infrared.
Solution Approach 2:
The patent changes the thermal field distribution parameters by introducing infrared radiation that penetrates the panel. This creates a more uniform temperature and moisture gradient throughout the resin layer, preventing the extreme surface conditions that lead to flow disturbances and quality defects.
3Productivity
If NIR radiation is used for drying, then drying speed is significantly increased, but the insulating effect of panels still causes some moisture gradients
Solution Approach 1:
The patent combines NIR radiation drying with hot air drying in a hybrid system. The NIR provides rapid internal heating and moisture evaporation through panel penetration, while the hot air component ensures uniform moisture removal from the surface and prevents moisture gradients by providing continuous convective drying throughout the process.
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 combined NIR/thermal drying method achieves a significant reduction in residual moisture, optimizing the resin flow and preventing visually unpleasant flow disturbances, with a preferred residual moisture range of 3 to 10%, enhancing the quality and consistency of the resin coating.
Implementation Method 1
an at least one-time irradiation of the at least one aqueous resin application with NIR radiation
Implementation Method 2
a subsequent at least one-time thermal treatment of the aqueous resin application irradiated with NIR radiation
Data Source
AI summary
The present invention relates to a method for drying at least one aqueous resin coating applied to at least one side of a substrate, comprising the steps of i) irradiating the at least one aqueous resin coating at least once with NIR radiation, and ii) subsequent thermal treatment of the aqueous resin coating irradiated with NIR radiation at least once. The present invention also relates to an apparatus for carrying out this method.