Plastic Lens Photochromic Coating With Low-Heat LED Curing
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Solution Overview
Problem
Existing methods for producing plastic lenses with photochromic coatings face challenges such as deformation of the lens due to heat from high-intensity light sources, incomplete curing leading to unsatisfactory adhesion, and complex operations, which affect productivity and photochromic properties.
Innovation Solution
The method employs a specific LED light source with a narrow emission peak wavelength (350-450 nm) to cure a photocurable coating on plastic lenses, minimizing heat-induced deformation and ensuring complete curing without the need for special cooling devices or additional materials, thus simplifying the production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-intensity light is used to cure the coating agent, then the curing speed and productivity are improved, but the plastic lens is softened by heat and deformed
Solution Approach 1:
The patent changes the wavelength parameter of the light source from conventional UV ranges to a specific range of 350-450 nm, which allows effective curing while minimizing heat generation. This parameter change enables high-intensity irradiation without causing lens softening or deformation, thus resolving the contradiction between curing speed and lens shape maintenance
Solution Approach 2:
The patent replaces conventional thermal curing methods or high-intensity UV curing with LED-based optical curing. This substitution uses photopolymerization initiated by specific wavelength light instead of heat or high-energy UV, achieving complete curing without thermal deformation of the plastic lens
2Shape
If the intensity of irradiated light is reduced to prevent lens deformation, then the lens shape is maintained, but the coating agent is not fully cured resulting in unsatisfactory adhesion and surface hardness
Solution Approach 1:
The patent changes the wavelength parameter to 350-450 nm range and uses LED light sources with specific emission characteristics. This allows using lower intensity light that doesn't deform the lens while still achieving complete curing through the appropriate wavelength match with the photopolymerization initiator, thus maintaining both lens shape and coating adhesion
3Reliability
If conventional light sources are used to cure the coating, then the curing process is effective, but the equipment complexity and cooling requirements increase
Solution Approach 1:
The patent substitutes conventional UV lamps or thermal curing systems with LED-based optical curing system. This replacement eliminates the need for complex cooling devices and additional materials while achieving effective curing through photopolymerization initiated by LED light in the 350-450 nm range
Solution Approach 2:
The LED light source inherently provides the appropriate wavelength for photopolymerization without requiring external cooling systems or additional components. The system is self-sufficient, using the LED's optical properties directly to cure the coating without needing separate cooling or control mechanisms
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 prevents lens deformation, maintains high photochromic properties, and enhances productivity by reducing curing time and equipment complexity, while ensuring uniform curing and improved adhesion of the coating layer.
Implementation Method 1
irradiating light from an LED having an emission peak wavelength of 350 nm or more to less than 450 nm
Implementation Method 2
curing a photocurable coating on plastic lenses
Implementation Method 3
Photochromism is a reversible function that a certain compound changes its color swiftly upon exposure to light including ultraviolet light such as sunlight
Data Source
AI summary
A method of producing a plastic lens having a cured coating layer, comprising the steps of: forming an uncured coating layer from a photocurable coating composition comprising at least a) a photochromic compound, b) a radically polymerizable monomer and c) a photopolymerization initiator on one surface of a plastic lens; and irradiating the plastic lens having the uncured coating layer with light from an LED having an emission peak wavelength of 350 nm or more to less than 450 nm from above the outer surface of the uncured coating layer to cure the uncured coating layer.