Curable Silsesquioxane Polymers for UV-Resistant Hard Coatings
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Solution Overview
Problem
Epoxy- or acrylate-based hard coatings exhibit poor outdoor weatherability, necessitating the development of new polymers with improved durability and resistance to UV and moisture exposure.
Innovation Solution
Curable silsesquioxane polymers with a three-dimensional branched network structure, incorporating ethylenically unsaturated groups and hydroxyl (-OH) groups, are used to create a protective coating that can be UV-cured, optionally with nanoparticles for enhanced hardness, and an organic solvent for processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy- or acrylate-based polymers are used to prepare hard coatings, then abrasion and scratch resistance are achieved, but outdoor weatherability deteriorates
Solution Approach 1:
The patent employs silsesquioxane polymers as a composite material alternative to conventional epoxy or acrylate-based polymers. These silsesquioxane polymers contain inorganic Si-O-Si networks combined with organic groups, creating a hybrid material structure that simultaneously provides hardness, abrasion resistance, and superior outdoor weatherability including UV and moisture resistance
2Strength
If silica nanoparticles are mixed with base polymer to create hard coating, then abrasion resistance is improved, but outdoor weatherability remains poor
Solution Approach 1:
The patent fundamentally changes the chemical composition parameter of the coating polymer from conventional organic polymers (epoxy or acrylate-based) to silsesquioxane polymers with inorganic Si-O-Si networks. This parameter change transforms the material's interaction with environmental factors, providing both the desired abrasion resistance and improved outdoor weatherability including UV and moisture resistance
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 resulting coatings demonstrate excellent outdoor weatherability, UV resistance, and moisture resistance, making them suitable for applications requiring durability and optical clarity, such as anti-scratch and anti-abrasion coatings for polycarbonate lenses and polyester films.
Implementation Method 1
a three-dimensional branched network which is a condensation reaction product of a compound having the formula Z—Y—Si(R1)3
Implementation Method 2
a curable composition that includes a photoinitiator (e.g., a free-radical initiator) and a curable silsesquoxane polymer
Implementation Method 3
optionally exposing the coated curable composition to conditions that allow an organic solvent, if present, to evaporate from the curable composition
Data Source
AI summary
A curable silsesquioxane polymer, a composition including such polymer, an article having a layer disposed thereon that includes the curable polymer and/or the cured polymer, and a method of forming a cured coating, wherein the curable silsesquioxane polymer includes a three-dimensional branched network having the formula: (I), or (II) wherein: the oxygen atom at the * is bonded to another Si atom within the three-dimensional branched network; R is an organic group comprising an ethylenically unsaturated group; R2 is an organic group that is not an ethylenically unsaturated group, and n or n+m is an integer of greater than 3; and the —OH groups are present in an amount of at least 15 wt-% of the polymer.