Covalent Silane Anti-Fog Coating for Optical Components
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Solution Overview
Problem
Current anti-fog coatings for optical components, such as eyeglass lenses, are not permanent and require regular application, and existing solutions that provide a permanent anti-fog effect often compromise the optical properties of the anti-reflective layers.
Innovation Solution
A cross-linked anti-fog coating is achieved by covalently attaching a silane derivative with specific hydrophilic groups to the optical component's surface, using a chemical reaction that cross-links neighboring molecules, thereby enhancing hydrolysis stability and reducing water contact angle, allowing for a durable anti-fog effect without impairing anti-reflective properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a permanent anti-fog coating is applied to an anti-reflective layer, then the anti-fog durability is improved, but the optical properties of the anti-reflective layer are compromised
Solution Approach 1:
The patent applies local quality by creating a surface layer with distinct properties from the bulk anti-reflective coating. The topmost nanometer-scale layer is engineered to be highly hydrophilic (contact angle <10°) while the underlying anti-reflective layers maintain their original optical properties. This is achieved through sequential coating where each layer has a specific function: the AR layers provide optical performance and the top antifog layer provides surface hydrophilicity without compromising the optical stack below.
Solution Approach 2:
The patent uses composite materials by combining multiple coating layers with different functions. The anti-reflective coating stack (typically TiO2, SiO2, or other dielectric layers) is combined with a top-layer antifog coating containing hydrophilic surfactants or polymers. This composite structure allows the AR layers to maintain their optical effectiveness while the composite surface layer provides permanent antifog protection through hydrophilic properties that prevent water droplet formation.
2Reliability
If hydrophilic surfactants are applied to the lens surface, then the anti-fog effect is improved, but the treatment requires regular reapplication
Solution Approach 1:
The patent applies preliminary action by incorporating hydrophilic functional groups directly into the coating formulation that is applied in advance during lens manufacturing or initial treatment. The coating contains surfactant molecules or polymers with hydrophilic moieties (such as polyethylene glycol chains, carboxylic acid groups, or hydroxyl groups) that are permanently bonded to the surface. This preliminary incorporation of functional groups ensures long-term antifog effect without requiring regular reapplication, as the hydrophilic groups remain anchored to the coating matrix.
Solution Approach 2:
The patent implements self-service through self-assembling monolayers or polymers that automatically orient themselves on the coating surface. The hydrophilic surfactant molecules spontaneously arrange with their hydrophobic tails anchored to the coating and hydrophilic heads exposed to the environment, creating a stable, self-maintaining antifog surface. This self-organizing behavior ensures the antifog effect persists without external intervention or regular reapplication.
3Illumination intensity
If the contact angle of water droplets is reduced, then light transmission is improved, but the coating requires permanent modification of the surface
Solution Approach 1:
The patent applies parameter changes by systematically adjusting the contact angle parameter to an extreme value (<10°) through controlled surface chemistry modification. This is achieved by selecting coating materials with specific surface energy characteristics and controlling the thickness and composition of the top antifog layer. By precisely controlling these parameters during manufacturing, the surface is modified to achieve ultra-low contact angle that maximizes light transmission while maintaining anti-reflective coating effectiveness.
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 permanent anti-fog effect that maintains high transmission and low scattered light, ensuring the optical clarity of the component while preventing regular reapplication of anti-fog treatments.
Implementation Method 1
covalent bonding of a silane derivative of formula (2) to the surface of an optical component... The covalent bonding of the compound of formula (2) to the surface of the optical component is achieved by at least one of the reactive, hydrolyzable -Si-X groups reacting with a suitable reactive surface group
Implementation Method 2
cross-linking of the hydrophilic groups -B2 of neighboring molecules of the antifog coating... cross-linking of neighboring molecules
Implementation Method 3
the terminal hydrophilic group -B2 is poly(meth)acrylate... A low contact angle of the water droplets is advantageous... treat the surface in such a way that the water droplets form a small contact angle with the surface
Data Source
Figure 1~2
Figure 3~4
AI summary
Optical component comprises an anti-fog coating obtained by covalent attachment of a silane derivative (I) to the surface of the optical component. Optical component comprises an anti-fog coating obtained by covalent attachment of a silane derivative of formula (R oX mSiA n) (I) to the surface of the optical component. either m : 1-3; n : 1-2; o : 0-1; or m+n+o : 4; X : halo or 1-4C alkoxy, where X is same or different, when m is 2-4; R : 1-4C alkyl; A : -A1-A2, where A is same or different, when n is 2; A1 : -arylene-, -1-6C-alkylene-arylene-, -arylene-1-6C-alkylene-, -1-6C-alkylene-arylene-1-6C-alkylene, -poly(3-6C-alkoxylene)-, (per)fluorinated-alkylene- and/or (per)fluorinated-poly(2-6C-alkoxylene)-, where A1 is connected to Si; and A2 : poly(meth)acrylate containing CH 2=C(CH 3)COOC 1 - 4-alkyl, CH 2=C(H)COOC 1 - 4-alkyl, hydroxyethylene methacrylate, 2-acrylamido-2-methylpropane sulfonic acid, trimethylolpropane triacrylate and/or pentaerythritol tetraacrylate, where A2 is terminally attached to A1. Independent claims are also included for: (1) an optical component comprising a cross-linked anti-fog coating obtained by covalent attachment of a silane derivative of formula (R oX mSiB1 n) (II) to the surface of the optical component and cross-linking adjacent molecules; and (2) preparing the cross-linked anti-fog coating on an optical component, comprising (a) covalently bonding a precursor silane derivative of formula (R oX mSiD1 n) (III) to the surface of the optical component, reacting the terminal group (-D3) with (meth)acrylate monomers to form a hydrophilic poly(meth)acrylate group, and cross-linking the hydrophilic poly (meth)acrylate groups of adjacent molecules of the anti-fog coating, or (b) providing the optical component and covalent bonding of (II) by chemical reaction with reactive groups on the surface of the optical component, and cross-linking the hydrophilic group (B3) of adjacent molecules of the anti-fog coating, or (c) providing the optical component and covalent bonding of (I) by chemical reaction with reactive groups on the surface of the optical component. B1 : B2-B3-, where B1 is same or different, when n is 2; B3 : terminal hydrophilic group, preferably poly(meth)acrylate containing CH 2=C(CH 3)COOC 1 - 4-alkyl, CH 2=C(H)COOC 1 - 4-alkyl, hydroxyethylene methacrylate, 2-acrylamido-2-methylpropane sulfonic acid, trimethylolpropane triacrylate and/or pentaerythritol tetraacrylate, where hydrophilic group is cross-linked with hydrophilic group of adjacent molecule of anti-fog layer; B2 : spacer, which connects B3 with Si, or covalent bond; D1 : D2-D3; D3 : terminal group with (meth)acrylate functionality; and D2 : spacer or covalent bond.