Photocurable Composition Stabilizing Leuco Dye Against Color Fading
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Solution Overview
Problem
Photocurable compositions used for applications like coatings and adhesives face issues with color fading in high temperature and high humidity environments due to acid detachment from leuco dyes, leading to compromised concealing properties.
Innovation Solution
A photocurable composition comprising a leuco dye, a salt with specific anions such as [P(Rf)aF6-a]−, [Sb(Rf)bF6-b]−, and [B(Rf)cF4-c]−, and a photoradical initiator, which inhibits acid detachment and subsequent color fading by enhancing acid mobility and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If carbon black pigment is mixed into the photocurable composition to impart concealing property, then the concealing property is improved, but the curability deteriorates because active energy rays are absorbed by the carbon black
Solution Approach 1:
The invention changes the chemical parameters of the pigment system by replacing carbon black with leuco dye compounds that have different optical and chemical properties. The leuco dye provides concealing property through its colored form while allowing UV penetration for curing, thus resolving the contradiction between concealing property and curability.
Solution Approach 2:
The invention uses a composite system comprising leuco dye, photoradical initiator, and ethylenically unsaturated compound. This composite material approach allows the leuco dye to provide concealing property while the photoradical initiator ensures proper curing, overcoming the limitation of carbon black that absorbed UV rays needed for curing.
2Reliability
If a photosensitive composition for casting containing leuco dye and photoacid generator is used to achieve black color with good photocurability, then the photocurability is improved, but the concealing property deteriorates due to color fading in high temperature and high humidity environments
Solution Approach 1:
The invention modifies the chemical environment of the leuco dye by introducing a specific base compound with a conjugated structure containing nitrogen atoms. This parameter change stabilizes the acid-leuco dye complex in high temperature and humidity conditions, preventing color fading while maintaining the black color and concealing property.
Solution Approach 2:
The base compound acts as an intermediary that forms a stable complex with the leuco dye and photoacid generator. This intermediary structure prevents acid detachment from the leuco dye in harsh environments, thereby maintaining color stability and concealing property while preserving photocurability.
3Illumination intensity
If the concentration of carbon black pigment is increased to improve concealing property, then the concealing property is improved, but the curability deteriorates more severely due to increased UV absorption
Solution Approach 1:
The invention changes the optical parameters of the pigment system by using leuco dye instead of carbon black. The leuco dye provides strong concealing property at lower concentrations while allowing sufficient UV penetration for curing, thus resolving the contradiction between concealing property and curability without the need to increase pigment concentration.
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 composition achieves excellent concealing properties and inhibited color fading in high temperature and high humidity environments, maintaining performance in conditions like 85°C and 85% RH or 100°C.
Implementation Method 1
a photocurable composition including the following components (A) to (D): component (A): a leuco dye; component (B): a salt having an anion selected from the group consisting of [P(Rf)aF6-a]−, [Sb(Rf)bF6-b]− and [B(Rf)cF4-c]−
Implementation Method 2
the main cause of occurrence of color fading of a cured product is based on detachment of an acid from a leuco dye in a high temperature and high humidity (85 C and 85% RH) environment or a high temperature (100 C) environment
Data Source
AI summary
An object of the present invention is to provide a photocurable composition from which a cured product having high concealing property is obtained by irradiation with an active energy ray such as ultraviolet ray, and which inhibits color fading of the cured product in a high temperature and high humidity (85 C and 85% RH) environment or a high temperature (100 C) environment.A photocurable composition including the following components (A) to (D):component (A): a leuco dye;component (B): a salt having an anion selected from the group consisting of [P(Rf)aF6-a]−, [Sb(Rf)bF6-b]− and [B(Rf)cF4-c]− (in the formulae, Rf represents a fluoroalkyl group having 1 to 20 carbon atoms, a and b each independently represent an integer of from 1 to 5, and c represents an integer of from 1 to 3);component (C): a radical polymerizable compound; andcomponent (D): a photoradical initiator.