Hardcoat Nanoparticle Mixture for Optical Clarity and Scratch Resistance
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Solution Overview
Problem
Existing coatings for optical displays, such as CRT and LED displays, lack optimal combinations of hardness and optical properties, necessitating the development of a hardcoat with improved transparency and durability.
Innovation Solution
A hardcoat comprising a binder and a mixture of nanoparticles with specific size ratios (2 nm to 200 nm and 60 nm to 400 nm) and weight percentages (60 wt.% to 90 wt.%), including combinations like 5 nm/190 nm, 5 nm/75 nm, 20 nm/190 nm, and 20 nm/75 nm, which provides enhanced hardness and transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hardcoat coating is applied to improve hardness, then scratch resistance and durability are improved, but transparency and optical clarity deteriorate
Solution Approach 1:
The nanoparticle fillers are segmented into multiple size ranges (2-200 nm and 60-400 nm) with different weight percentages. This segmentation allows smaller particles to fill gaps between larger particles, creating a denser packing structure that enhances hardness while maintaining transparency by reducing light scattering interfaces.
Solution Approach 2:
Different regions of the coating composition have different nanoparticle size distributions optimized for specific functions: smaller particles (2-200 nm) provide hardness enhancement while larger particles (60-400 nm) contribute to structural integrity. The specific weight percentage distribution (10-50% small particles, 50-90% large particles) creates local quality variations that simultaneously achieve both hardness and transparency.
2Strength
If nanoparticle concentration is increased to enhance hardness, then durability is improved, but coating viscosity and application difficulty increase
Solution Approach 1:
The nanoparticle size distribution parameters are changed to include a broad range (2-400 nm) with specific weight percentage ratios. This parameter change allows the coating to maintain optimal viscosity for application while achieving high nanoparticle loading (60-90 wt.%) for enhanced hardness. The multi-size distribution prevents agglomeration and improves flow characteristics.
3Strength
If larger nanoparticles are used to improve hardness, then scratch resistance is enhanced, but light scattering increases and transparency decreases
Solution Approach 1:
The filler particles are segmented into two distinct size ranges: small particles (2-200 nm) that minimize light scattering and maintain transparency, and large particles (60-400 nm) that provide scratch resistance through structural reinforcement. The segmented size distribution allows each particle size to perform its optimized function without compromising the other property.
Solution Approach 2:
The coating uses a composite nanoparticle system combining particles of different sizes (2-200 nm and 60-400 nm) in specific weight ratios. This composite approach leverages the advantages of both small particles (transparency) and large particles (hardness) to achieve a coating that simultaneously provides scratch resistance and optical clarity.
Data Source
Figure 1
AI summary
Hardcoat and precursor therefore comprising a binder and a mixture of nanoparticles in a range from 40 wt. % to 95 wt. %, based on the total weight of the hardcoat, wherein l0wt. % to 50 wt. % of the nanoparticles have an average particle diameter in a range from 2 nm to 200 nm and 50 wt. % to 90 wt. % of the nanoparticles have an average particle diameter in a range from 60 nm to 400 nm, and wherein the ratio of average particle diameters of nanoparticles having an average particle diameter in the range from 2 nm to 200 nm to average particle diameters of nanoparticles having an average particle diameter in the range from 60 nm to 400 nm is in a range from 2: 1 to 200: 1. Hardcoat described herein are useful, for example, for optical displays (e.g., cathode ray tube (CRT), light emitting diode (LED) displays), and of devices such as personal digital assistants (PDAs), cell phones, liquid crystal display (LCD) panels, touch- sensitive screens and removable computer screens; and for body of such devices.