Primer Composition for Plastic Lenses Resolving Adhesion and Impact Trade-offs
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Solution Overview
Problem
Existing primer compositions for plastic lenses face challenges in achieving sufficient adhesion, impact resistance, and uniform smoothness, particularly when used with various plastic materials, and often require high-temperature curing, which can lead to thermal deformation or color changes, and the use of organic solvents results in environmental issues and storage stability concerns.
Innovation Solution
A primer composition comprising an aqueous dispersion of urethane resin with a polycarbonate-derived skeleton, combined with specific solvents and inorganic oxide fine particles, which improves adhesion, impact resistance, and abrasion resistance, while maintaining storage stability and reducing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard coating layer is laminated on the plastic lens surface to improve abrasion resistance, then the abrasion resistance is improved, but the impact resistance is lowered
Solution Approach 1:
The coating system is divided into multiple functional layers: a primer coating layer (containing urethane resin and inorganic oxide fine particles) applied first to improve impact resistance, followed by a hard coating layer applied subsequently to provide abrasion resistance. This segmentation allows each layer to perform its specific function without compromising the other.
2Reliability
If a primer coating layer is inserted between plastic lens and hard coating layer to improve impact resistance, then the impact resistance is improved, but the adhesion is insufficient depending on plastic material types
Solution Approach 1:
The primer composition parameters are optimized by controlling the inorganic oxide fine particles content at 1-50 parts by weight per 100 parts by weight of urethane resin, and the organosilicon compound content at 1-30 parts by weight per 100 parts by weight of urethane resin. This parameter control ensures adequate adhesion to various plastic materials while maintaining impact resistance improvement.
Solution Approach 2:
The primer coating layer uses a composite material system combining urethane resin with inorganic oxide fine particles (such as silica, alumina, or titania) and organosilicon compounds. This composite structure provides both mechanical strength for impact resistance and chemical properties for adhesion to different plastic substrates.
3Strength
If the primer coating layer is cured at high temperatures to improve adhesion, then the adhesion is improved, but the plastic lens may be thermally deformed or colored
Solution Approach 1:
The curing temperature parameter is reduced from conventional high temperatures to 80°C or lower, which prevents thermal deformation and coloration of the plastic lens while still achieving adequate adhesion through the optimized primer composition containing inorganic oxide fine particles and organosilicon compounds.
4Ease of manufacture
If organic solvents such as toluene are used in the primer composition to improve dissolution, then the dissolution is improved, but odor generation and environmental issues occur
Solution Approach 1:
The harmful organic solvents are replaced with water as the dispersion medium, creating an aqueous dispersion system. This conversion eliminates odor and environmental issues while maintaining adequate dissolution and coating performance through the use of urethane resin and inorganic oxide fine particles that are compatible with aqueous environments.
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 primer composition enhances the adhesion and impact resistance of plastic lenses, achieves uniform smoothness, and improves the adhesion of photochromic coating layers, while being environmentally friendly and stable over time.
Implementation Method 1
a primer composition comprising an aqueous dispersion of urethane resin... improves the adhesion and impact resistance of plastic lenses
Implementation Method 2
a hard coating layer which is obtained by curing a hard coating layer-forming coating composition comprising inorganic comprising oxide fine particles
Implementation Method 3
a hard coating layer-forming coating composition comprising inorganic comprising oxide fine particles and an organosilicon compound
Data Source
Figure 1~3
AI summary
A primer coating composition is provided for an optical article capable of forming a coating layer having excellent impact resistance, abrasion resistance, and adhesion to various kinds of plastic materials without occurring of appearance faulty for an optical base material, for example, a plastic lens for an eyeglass. A primer composition for an optical article comprises; (A) aqueous dispersion of urethane resin having a polycarbonate-derived skeleton and the elongation of 200 ∼ 1000%; (B) an organic solvent having 3 ∼ 9 carbon atoms and having an ether bond or carbonyl bond and one hydroxyl group in a molecule; and (C) lower alcohol having 1 ∼ 4 carbon atoms, wherein the weight ratio of said organic solvent to said lower alcohol is from 0.01 to less than 2.00.