Hard Coating Composition Preventing Curling via Acrylate Monomers
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Solution Overview
Problem
Conventional hard coating compositions for mobile device substrates face challenges in achieving high hardness while preventing curling, warping, and cracking, especially as the thickness of the coating layer increases, which affects their practical application.
Innovation Solution
A hard coating composition comprising a tri- to hexa-functional acrylate-based monomer, inorganic particles, and a photoinitiator, with a solid content to organic solvent weight ratio of 70:30 to 99:1, which also includes optional mono- to di-functional acrylate-based monomers and photocurable elastic polymers, to enhance hardness and flexibility without curling or cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the hard coating layer is increased to improve surface hardness, then the surface hardness becomes higher, but the hard coating layer becomes wrinkled or curled due to curing shrinkage and may be easily cracked or exfoliated
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by using tri- to hexa-functional acrylate-based monomers with high crosslinking density. This parameter change allows the coating to achieve high hardness while maintaining flexibility and reducing curing shrinkage, thus preventing curling and cracking even at increased thicknesses
Solution Approach 2:
The invention creates a composite coating system combining organic binder (acrylate-based monomer), inorganic particles (silica, alumina, or titanium oxide), and photoinitiator. This composite structure provides both the hardness from inorganic particles and the flexibility from the organic matrix, resolving the contradiction between hardness and stability
2Strength
If a hard coating layer is formed to replace glass panels, then the mechanical strength is improved, but the coating layer may be easily cracked or exfoliated due to curing shrinkage
Solution Approach 1:
The invention modifies the binder chemistry by selecting tri- to hexa-functional acrylate-based monomers that provide optimal balance between crosslinking density and flexibility. This parameter optimization ensures the coating achieves glass-replacement hardness while maintaining adhesion and resistance to cracking and exfoliation
Solution Approach 2:
The invention creates local quality differentiation within the coating by incorporating inorganic particles (silica, alumina, or titanium oxide) that provide localized hardness enhancement while the organic binder matrix maintains overall flexibility and adhesion, preventing cracking and exfoliation
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 forms a hard coating film with high hardness, scratch resistance, and transparency, effectively preventing curling and cracking, even at increased thicknesses, making it suitable for mobile device substrates.
Implementation Method 1
a photoinitiator; and an organic solvent, wherein a solid content includes the binder, the inorganic particles and the photoinitiator
Data Source
AI summary
The present invention relates to a hard coating composition, and, more particularly, to a hard coating composition used in forming a hard coating film exhibiting high hardness and excellent properties. The hard coating composition can be used to form a high-hardness hard coating film that is not easily curled.