UV Drying Oven with Nitrogen Inert Atmosphere
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Solution Overview
Problem
Industrial processes for drying painted panels using solvent-based coatings are inefficient, requiring long times, consuming significant energy, and exposing operators to harmful vapors, while UV polymerization is hindered by oxygen in the air atmosphere.
Innovation Solution
A method and apparatus for photopolymerizing/drying chemicals using UV radiation in a nitrogen atmosphere, with a conveying system, UV polymerization chamber, and nitrogen generation system, allowing for a controlled inert atmosphere and reduced photo-initiator content in paints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solvent-based coatings are used for painting panels, then the coating can be applied in liquid phase with good coverage, but the drying process requires long times and consumes significant energy
Solution Approach 1:
The invention changes the chemical composition parameters of the coating from solvent-based to water-based or solvent-free formulations, and changes the curing mechanism from evaporative drying to photopolymerization. This allows the coating to transition from a physical drying process to a chemical curing process that occurs rapidly under UV irradiation, reducing drying time from hours to minutes while maintaining good coverage properties
Solution Approach 2:
The invention utilizes the phase transition of photoinitiators under UV irradiation to trigger polymerization. The photoinitiator absorbs UV energy and undergoes a phase change from inactive to active state, initiating the polymerization reaction that rapidly cures the coating. This phase transition mechanism enables fast curing without the need for prolonged thermal drying
2Loss of energy
If solvent-based coatings are heated for drying, then solvent evaporation is facilitated, but energy consumption increases significantly
Solution Approach 1:
The invention replaces the thermal drying system with a photopolymerization system. Instead of using thermal energy to evaporate solvents, UV light energy is used to initiate chemical polymerization. This substitution of energy type (from thermal to radiant) and mechanism (from evaporation to polymerization) dramatically reduces energy consumption while maintaining or improving drying efficiency
Solution Approach 2:
The invention employs periodic or continuous UV irradiation to trigger photopolymerization at controlled intervals. The UV lamps are activated only when panels pass through the curing zone, providing energy on-demand rather than continuous heating. This periodic action reduces overall energy consumption compared to continuous thermal drying while maintaining high productivity
3Productivity
If UV radiation is used for polymerization in air atmosphere, then curing occurs in shorter times, but oxygen in the air inhibits polymerization efficiency
Solution Approach 1:
The invention creates an inert atmosphere environment by replacing air with nitrogen or other inert gases in the polymerization chamber. This inert atmosphere eliminates oxygen inhibition while maintaining the benefits of UV polymerization. The nitrogen atmosphere allows UV light to penetrate and activate photoinitiators without oxygen interference, achieving both fast polymerization speed and complete curing
Solution Approach 2:
The invention uses nitrogen gas as an intermediary medium between the UV radiation and the coating. The nitrogen atmosphere serves as a protective intermediary that allows UV photons to reach the photoinitiator without being absorbed or scattered by oxygen molecules, thereby enabling efficient polymerization while maintaining a controlled environment
4Object-affected harmful factors
If conventional drying ovens are used, then panels can be dried in natural atmosphere, but harmful solvent vapors are released exposing operators to health risks
Solution Approach 1:
The invention converts the harmful solvent-based system into a beneficial water-based or solvent-free system. By replacing organic solvents with water or eliminating solvents entirely, the process eliminates harmful vapor emissions. The photopolymerization process itself becomes beneficial by providing a rapid, low-emission curing method that protects operator health while maintaining coating quality
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
This approach reduces manufacturing time, energy consumption, and health risks by enabling faster polymerization with lower photo-initiator usage, resulting in cost savings, improved product quality, and reduced environmental impact.
Implementation Method 1
irradiating the material to be polymerized with UV radiations having suitable wavelength and appropriate intensity
Implementation Method 2
the fact that the oxygen (O2) present in earth atmosphere inhibits polymerization obtained through UV radiations has been known for at least 40 years. Consequently, UV polymerization in inert atmosphere (i.e. oxygen-free) is known
Data Source
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AI summary
Method for polymerizing and/or drying photopolymerizable/dryable coatings like paints or glue applied on panels (27), comprising the following steps: - Painting at least a panel (27) with a paint containing at least a photoinitiator sensitive to an UV radiation; - Performing the polymerization/drying of said panel (27) inside a polymerization chamber (24) comprising an UV polymerizing lamp (25), said chamber being provided with an inert atmosphere; in said inert atmosphere the atmospheric oxygen being totally or partially replaced by nitrogen produced at the moment of the polymerization/drying using nitrogen generating systems (3) starting from natural earth atmosphere, characterized in that the polymerization is carried out in an inert atmosphere comprising a variable percentage content of nitrogen between 90% and at most 99,9999% corresponding to a percentage content of oxygen between 10% and more than 0,0001%.