Polymeric Transparent Article Gradient Tinting by UV Photodegradation
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Solution Overview
Problem
Current methods for tinting polymeric substrates, such as polycarbonate lenses, fail to achieve gradient tints effectively, either using aggressive solvents, complex apparatus, or limited gradient types, and are not suitable for annular gradient tinting, which is desirable for ophthalmic applications.
Innovation Solution
A method involving UV radiation to photodegrade the surface of polymeric substrates in a controlled gradient pattern, followed by dyeing with a dyeing agent to achieve linear or geometrical gradient tints without using harmful solvents or complex equipment, allowing for stable and long-lasting coloration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If impregnating solvents are used to tint polymeric substrates with gradient, then gradient tint can be achieved, but the method uses aggressive solvents which are not safe and not suitable for ophthalmic application
Solution Approach 1:
The patent replaces chemical impregnating solvents with UV light irradiation to create the gradient tint effect. The UV light photodegrades the polycarbonate substrate to a controlled depth, allowing dye to penetrate only to that depth, creating gradient tint without using aggressive chemical solvents.
Solution Approach 2:
The patent changes the physical state and properties of the polycarbonate substrate by irradiating it with UV light, causing photodegradation that creates a gradient in molecular structure and permeability. This allows controlled dye penetration based on light intensity and exposure time, achieving gradient tint through physical parameter changes rather than chemical solvents.
2Reliability
If uniform UV radiation is applied to photodegrade the substrate surface, then the substrate can be dyed, but it leads to a uniform colour on the whole surface instead of gradient tint
Solution Approach 1:
The patent applies UV light irradiation with varying intensity across different regions of the substrate surface. By controlling the spatial distribution of UV light intensity, the photodegradation depth varies locally, creating zones with different dye penetration capabilities and thus achieving gradient tint patterns.
Solution Approach 2:
The patent uses dynamic control of UV light exposure parameters (intensity, duration, pattern) to create the desired gradient tint. The irradiation process can be adjusted in real-time to produce different gradient patterns, and the photodegradation process itself creates a dynamic gradient in substrate permeability that guides dye penetration.
3Manufacturing precision
If the substrate is immersed into a dying bath and withdrawn slowly, then gradient tint can be achieved, but the method is aggressive to the surface and not suitable for ophthalmic application
Solution Approach 1:
The patent replaces the mechanical immersion and withdrawal process with UV light irradiation to create the gradient tint. This eliminates contact with aggressive dying bath chemicals and their associated surface damage, while still achieving the desired gradient effect through controlled photodegradation.
4Manufacturing precision
If heating furnace is used to diffuse dye into the lens, then gradient tint can be achieved, but the method is not very easy to carry out and not always leads to a very regular tint gradient
Solution Approach 1:
The patent replaces the thermal diffusion process in a heating furnace with UV light irradiation. This eliminates the need for complex temperature control and long heating cycles, while providing more precise and regular gradient control through optical means. The UV irradiation method is simpler to implement and yields more consistent results.
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 method allows for easy and effective gradient tinting of polymeric substrates, including polycarbonate lenses, achieving stable and customizable color gradients without altering the substrate's properties, suitable for both linear and annular gradients, and is environmentally friendly.
Implementation Method 1
irradiating a least one face of the substrate with UV radiation causing the surface of the substrate to be photodegraded over a determined thickness
Implementation Method 2
contacting the irradiated face of the substrate with a colouring agent so as to diffuse the colouring agent in the entire thickness of the photodegraded surface layer of the substrate
Data Source
AI summary
A method for dyeing a transparent article made of a polymeric substrate with gradient tint comprising: a) a first step of photodegrading the polymeric substrate (1) of the transparent article, by irradiation (3) of at least one first surface of the article to UV radiations to produce a gradiently photodegraded surface layer of the polymeric substrate, and b) a second step of dyeing said first face of the article with a dyeing agent so as to diffuse said dyeing agent into the gradiently photodegraded surface layer of the polymeric substrate.