Plastic Lens Primer Composition with Polycarbonate Urethane Resin
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Solution Overview
Problem
Existing primer compositions for plastic lenses face issues such as insufficient adhesion, whitening, long curing times, and reduced impact resistance, particularly when used with various plastic materials, and they often compromise the optical properties and storage stability.
Innovation Solution
A primer composition comprising a urethane resin with a polycarbonate-derived skeleton, a polyester resin, inorganic oxide fine particles, and water, with specific weight ratios and properties to enhance adhesion, impact resistance, and optical properties, including a high refractive index, while improving storage stability and reducing interference patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard coating layer is laminated on the surface of a plastic lens to improve abrasion resistance, then the surface hardness and scratch resistance are improved, but the impact resistance of the plastic lens is decreased
Solution Approach 1:
The coating system is divided into multiple functional layers: a primer coating layer (first coating layer) applied directly to the plastic lens surface to maintain impact resistance, and a hard coating layer (second coating layer) applied over the primer to provide abrasion resistance. This segmentation allows each layer to perform its specific function without compromising the overall lens performance.
2Illumination intensity
If an antireflection coating layer is laminated on the hard coating layer to inhibit reflected light, then the optical quality is improved, but the impact resistance of the plastic lens is lowered more increasingly
Solution Approach 1:
The coating structure is segmented into three layers: primer coating layer, hard coating layer, and antireflection coating layer. The primer layer serves as a buffer between the plastic lens and the hard coating layer, absorbing impact stress and preventing it from reaching the lens, thereby maintaining impact resistance while allowing the antireflection layer to be applied for optical quality improvement.
3Reliability
If a primer coating layer is inserted between the plastic lens and hard coating layer to improve impact resistance, then the impact resistance is improved, but the adhesion may be insufficient depending on the types of plastic materials
Solution Approach 1:
The primer coating composition is formulated with specific parameters: it contains 5-50 mass% of a polyester resin with a glass transition point of -50°C or lower, 5-50 mass% of a polyether resin with a glass transition point of -50°C or lower, and 50-80 mass% of an inorganic oxide fine particles. These parameter specifications ensure both adequate adhesion to various plastic lens materials and sufficient impact resistance.
4Reliability
If a primer composition comprising a mixture of a urethane resin and inorganic oxide fine particles is used, then the impact resistance is improved, but the primer coating layer is whitened and long time is required for curing
Solution Approach 1:
The invention replaces urethane resin with a specific composition containing polyester resin and polyether resin with glass transition points of -50°C or lower. This parameter change in the resin type eliminates the whitening problem and reduces curing time to 5 minutes or less at 100°C, while maintaining impact resistance through the high content (50-80 mass%) of inorganic oxide fine particles.
5Illumination intensity
If the refractive index of the primer coating layer is not matched to high refractive index plastic lenses, then an interference pattern is generated, but adjusting the refractive index may compromise other properties
Solution Approach 1:
The primer coating is formulated as a composite material containing 50-80 mass% inorganic oxide fine particles (such as titanium oxide, zirconium oxide, or zinc oxide) dispersed in a matrix of polyester resin and polyether resin. This composite structure enables the coating to achieve a high refractive index (1.8 or higher) to match high refractive index plastic lenses and reduce interference patterns, while maintaining adequate adhesion and impact resistance through the resin matrix and optimized particle distribution.
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 significantly improves the adhesion and impact resistance of plastic lenses, reduces whitening, and enhances the optical properties, providing a stable and effective coating that maintains performance across different plastic materials.
Implementation Method 1
the refractive index of a primer coating layer laminated is important. This is because that an interference pattern is generated caused by the difference in refractive index between the plastic lens and the primer coating layer
Implementation Method 2
a photochromic coating layer showing photochromic properties which is formed on said primer coating layer
Data Source
Figure 1~2
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AI summary
A primer coating composition is provided for an optical article capable of forming a coating layer having excellent impact resistance, abrasion resistance, adhesion and high refractive index to an optical base material, having high refractive index, specifically a plastic lens without occurrence of poor appearance such as ununiformity, cloudiness, etc. and regardless of the materials of the plastic lens. A primer composition for an optical article may comprises urethane resin having a polycarbonate-derived skeleton, polyester resin, inorganic oxide fine particles and water, and water-soluble organic solvent, if necessary.