Stamp-Marking Ink for Ophthalmic Lenses
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Solution Overview
Problem
Current inks for stamp-marking ophthalmic lenses face challenges such as slow drying times, poor compatibility with lens surfaces, instability, and the occurrence of ghost images after removal, while also containing CMR substances that need to be replaced due to regulatory compliance issues.
Innovation Solution
A 'one component' ink composition comprising a polyurea-urethane copolymer (compound of formula I), a drying aid, and at least one pigment, which provides good compatibility with lens surfaces, fast drying times, and stability, while being environmentally friendly and free from CMR substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional inks use castor oil and derivatives as principal solvents, then good adhesion on lens surface is achieved, but drying speed becomes extremely slow
Solution Approach 1:
The patent changes the chemical parameters of the ink composition by replacing castor oil-based solvents with a specific polyurea-urethane copolymer (formula I) and adjusting the solvent mixture to include water, alcohols, and esters. This parameter change enables the ink to maintain adhesion while achieving fast drying within 4-7 hours, directly resolving the contradiction between adhesion strength and drying speed.
2Strength
If CMR substances are used to improve compatibility with lens surface, then good adhesion is achieved, but regulatory compliance becomes problematic
Solution Approach 1:
The patent extracts and removes CMR substances (carcinogenic, mutagenic, and reproductive toxic substances) from the ink formulation while maintaining the essential adhesion function. The copolymer (formula I) provides compatibility with lens surfaces without requiring harmful CMR additives, thus eliminating the harmful factors while preserving the beneficial adhesion property.
Solution Approach 2:
The patent uses a composite polymer structure (polyurea-urethane copolymer with specific functional groups) that combines multiple chemical functionalities in one molecule. This composite material approach provides both adhesion and lens compatibility without needing separate CMR substances, resolving the contradiction between performance and safety.
3Object-affected harmful factors
If commercial CMR-free alternative inks are used, then regulatory compliance is achieved, but ghost image defects occur
Solution Approach 1:
The patent changes the chemical composition parameters by introducing the specific copolymer (formula I) with controlled molecular structure and functionality. This parameter optimization allows the ink to be CMR-free while preventing ghost images through proper film formation and adhesion characteristics, thus resolving both requirements simultaneously.
4Device complexity
If vinyl or acrylic homo- or copolymers are used as principal components, then ink composition is simplified, but ease of removal with usual solvents deteriorates
Solution Approach 1:
The patent modifies the polymer structure parameters by using a polyurea-urethane copolymer with specific functional groups that balance simplicity of composition with removability. The copolymer's chemical structure allows it to be removed with usual solvents like alcohol and water, maintaining ease of operation while keeping the composition relatively simple.
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 ink composition achieves fast drying within 4 to 7 hours, excellent adhesion on various lens substrates, and prevents ghost image formation after removal, while being compliant with environmental and health safety standards.
Implementation Method 1
At each end of its chain, it comprises one urethane group which enables the formation of a hard film
Implementation Method 2
The drying aid allows to adjust the drying time of the marking ink. A fast drying time, i.e. within 4 to 7 hours, is aimed at
Implementation Method 3
the compound of formula 1 dissolves easily in solvents, in particular in standard solvents such as water and alcohols
Data Source
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AI summary
An ink composition for stamp-marking on an ophthalmic lens, said composition comprising at least: - a compound of formula (I) wherein n is 1 or 2, - a drying aid, and - at least one pigment.