Silane Hardcoat Coating for Water-Erasable Permanent Marker Surfaces
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Solution Overview
Problem
There is a need for rewritable writing surfaces that exhibit durable performance and good erasability, especially for permanent marker writing with water, and for hardcoat coating compositions with improved stability.
Innovation Solution
A hardcoat layer is formed using a composition comprising hydrolyzed and condensed first silane monomers, optionally with second silane monomers, and silica nanoparticles, which can be further enhanced with a hydrophilic silane surface layer to improve erasability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hardcoat coating is applied to provide durability and abrasion resistance, then the coating strength and hardness are improved, but the erasability of permanent marker writing deteriorates
Solution Approach 1:
The coating system is divided into two functional layers: a hardcoat layer providing durability and abrasion resistance, and a surface layer providing erasability. This segmentation allows each layer to independently perform its specific function without compromising the other, resolving the contradiction between strength and erasability.
Solution Approach 2:
Different regions of the coating system have different properties: the hardcoat layer has high hardness and strength for durability, while the surface layer has low surface energy for easy cleaning. This local differentiation of properties allows simultaneous achievement of both durability and erasability.
2Duration of action of stationary object
If a hardcoat coating is applied to provide abrasion resistance, then the coating durability is improved, but the stability of the coating composition deteriorates
Solution Approach 1:
The hardcoat layer is formulated as a composite material containing silane polymers, silica nanoparticles, and crosslinking agents. This composite structure provides both durability through the hard coat formation and stability through the controlled crosslinked network, resolving the contradiction between durability and compositional stability.
3Ease of operation
If the surface energy of the coating is reduced to improve erasability, then the ease of cleaning is improved, but the coating adhesion and durability deteriorate
Solution Approach 1:
The coating system is segmented into a hardcoat layer with high adhesion properties and a surface layer with low surface energy. This segmentation allows the surface layer to provide easy cleaning while the hardcoat layer maintains strong adhesion to the substrate, resolving the contradiction between ease of cleaning and adhesion.
Solution Approach 2:
The surface layer is specifically designed with low surface energy properties for easy cleaning, while the hardcoat layer maintains high adhesion properties. This local differentiation of surface properties allows simultaneous achievement of easy cleaning and strong adhesion without compromise.
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 solution provides a tough, abrasion-resistant layer with improved erasability of permanent marker writing, allowing easy removal with water and maintaining coating stability.
Implementation Method 1
The hardcoat layer comprises the hydrolyzed and condensed reaction product of a composition comprising: i) first hydrophobic silane monomer(s) having the formula R1Si(OR)3
Implementation Method 2
The hardcoat layer comprises the hydrolyzed and condensed reaction product of a composition comprising
Data Source
AI summary
Articles are described comprising a substrate and a hardcoat layer disposed on the substrate. The hardcoat layer comprises the hydrolyzed and condensed reaction product of a composition comprising: i) first hydrophobic silane monomer(s) having the formula R1Si(OR)3 wherein R and R1 is methyl or ethyl; ii) optional second silane monomer(s) having the formula (R2)4-mSi(OR)m or Si(OR)4, wherein R, R1 and R2 are organic groups with the proviso that R1 is not methyl or ethyl and m ranges from 1 to 3. The hardcoat layer may further comprises 10 to 30 wt. % silica nanoparticles. A surface layer comprising a hydrophilic silane may be disposed on the hardcoat layer. Also described is a method of using an article having a rewritable surface, hardcoat coating compositions, and methods of making hardcoat compositions and articles.