Silsesquioxane Derivative Composition for Low-Shrinkage Hard Coats
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Solution Overview
Problem
Existing hard coat agents lack sufficient hardness and exhibit high curing shrinkage ratios, which can lead to issues such as curling and reduced durability.
Innovation Solution
A silsesquioxane derivative with a specific molecular structure and a curable composition containing it, which undergoes controlled hydrolysis with limited water addition to achieve a low curing shrinkage ratio and high hardness, along with a hard coat agent and substrate application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional curable compositions are used to form hard coat layers, then coating and curing can be achieved, but the cured products exhibit insufficient hardness and high curing shrinkage ratios
Solution Approach 1:
The patent employs silsesquioxane derivatives as organic-inorganic hybrid materials that combine the advantages of both organic and inorganic components. The silsesquioxane cage structure provides exceptional hardness and dimensional stability, while the organic functional groups enable UV curing. This composite approach resolves the contradiction by achieving high hardness without excessive curing shrinkage, as the inorganic silsesquioxane framework maintains structural integrity during curing.
Solution Approach 2:
The patent optimizes the molecular structure parameters of the silsesquoxane derivative, specifically controlling the ratio of different silicon-containing units (R1SiX3 units with specific configurations). By adjusting the molecular weight, functional group distribution, and cage structure composition, the patent achieves a balance between hardness and curing shrinkage ratio, transforming the physical and chemical parameters to resolve the technical contradiction.
2Strength
If high crosslinking density is achieved to improve hardness, then the cured product becomes harder, but curing shrinkage increases causing curling and reduced durability
Solution Approach 1:
The silsesquoxane cage structure acts as a pre-formed three-dimensional crosslinked unit that provides high crosslinking density without the need for extensive post-curing reactions. The inorganic Si-O-Si backbone creates a rigid framework that maintains dimensional stability, while the organic functional groups provide controlled crosslinking. This composite structure achieves high hardness while minimizing curing shrinkage-induced dimensional changes.
Solution Approach 2:
The silsesquioxane derivative is pre-synthesized with a defined cage structure that already contains the crosslinked framework before application. This preliminary formation of the rigid inorganic core eliminates the need for extensive crosslinking reactions during curing, thereby reducing curing shrinkage and preventing curling, while still achieving the desired hardness through the pre-formed cage structure.
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 silsesquioxane derivative provides a cured product with an elastic modulus above 4.0 GPa, low curing shrinkage ratio of 7.3% or less, and excellent storage stability, reducing curling and enhancing durability.
Implementation Method 1
a method of producing the silsesquioxane derivative, the method including a step of hydrolyzing at least one organic silicon compound represented by RnSiXp
Implementation Method 2
a curable composition is coated on a substrate using any of various known coating methods, and then the coated curable composition is cured by being irradiated with an active energy ray such as ultraviolet light
Data Source
AI summary
The present invention provides: a silsesquioxane derivative which is represented by Formula (1), and in which a cured product obtained by curing the derivative has an elastic modulus at 23° C. of more than 4.0 GPa, and a method of producing the same; a curable composition including the silsesquioxane derivative and a polymerization initiator; a hard coat agent including the curable composition; a cured product obtained by curing the curable composition; a hard coat obtained by curing the hard coat agent; and a substrate including the hard coat. In Formula (1), at least one of u or v is a positive number.