Temporary Protective Lacquer for Optical Elements

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Solution Overview

Problem

The production and finishing of complex optical elements are challenging due to the need for precise application and removal of absorber varnishes on reflective and transmissive surfaces without contaminating transmissive surfaces, which can lead to image errors or loss of transmission.

Innovation Solution

A lacquer composition comprising a thiol compound with two or more thiol groups, a compound with two or more carbon-carbon double bonds, and a release agent with an alkyl radical of 4-20 carbon atoms, which forms a protective lacquer that balances adhesion and removability, ensuring protection against chemical and physical influences during manufacturing and can be easily peeled off.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If absorber lacquer is applied to reflective surfaces with sharp edges, then stray light is eliminated and surfaces are protected, but transmissive surfaces may be contaminated causing image errors or transmission loss

Engineering Contradiction:
Improvestray light eliminationVSAvoidsurface contamination control
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The optical element surface is segmented into different functional zones (reflective surfaces requiring absorber coating and transmissive surfaces requiring protection). A masking layer is applied selectively to transmissive surfaces to segment them from the absorber coating process, preventing contamination while allowing absorber lacquer to be applied to reflective surfaces for stray light elimination.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A masking layer acts as an intermediary substance between the absorber lacquer and transmissive surfaces. This intermediate layer prevents direct contact and contamination of transmissive surfaces during the absorber coating process, while still allowing the absorber lacquer to perform its function on exposed reflective surfaces.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If protective coating strongly adheres to optical surfaces, then protection against chemical and physical influences is improved, but removal without residue becomes difficult

Engineering Contradiction:
Improveprotection stabilityVSAvoidcoating removability
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The masking layer composition parameters are specifically designed to achieve optimal adhesion strength - strong enough to provide reliable protection during manufacturing processes (resisting chemicals, solvents, and mechanical handling) but weak enough to allow complete removal without residue. The parameter range includes specific polymer composition ratios and thickness specifications that balance these opposing requirements.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The masking layer is formulated as a composite material combining multiple polymer components with complementary properties. This composite structure provides both strong protective adhesion during manufacturing and controlled removability, achieving the balance between protection stability and ease of removal that single-material coatings cannot achieve.

Inventive Principle:
Principle #40Composite materials

3Manufacturing precision

If transmissive surfaces are protected during manufacturing, then contamination is prevented, but the protection must be completely removable without leaving residue

Engineering Contradiction:
Improvesurface cleanlinessVSAvoidresidue formation
Core Design Contradiction:
Manufacturing precisionVSLoss of substance

Solution Approach 1:

The masking layer is designed as a temporary, disposable protective coating that serves its purpose during manufacturing and is then completely removed. It is formulated to provide adequate protection during the manufacturing process but is intentionally designed to be completely removable without residue, accepting that the material will be discarded after use rather than remaining on the optical surface.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 lacquer composition provides excellent protection and removability, maintaining optical surface integrity through radical polymerization, stability against subsequent processes, and minimal residue removal, ensuring precise and residue-free application.

Implementation Method 1

The developed polymer system is based on the principle of radical polymerization of thiol-ene systems

Methodology Applied
Scientific EffectRadical polymerization: Photopolymerisation

Implementation Method 2

the release agent accumulates at the interface during the curing process, allowing the protective coating to be easily removed from the optical surface to be protected

Methodology Applied
Scientific EffectInterface accumulation: Adsorption

Data Source

PatentEP3475740B1Temporary protective lacquer for optical element
Publication Date: 2024.12.18 TOOZ TECH GMBH
  • EP3475740B1 patent drawingFigure 1~2

AI summary

A lacquer composition is provided, comprising 20%-79.9% by weight, based on the total weight of the composition, of a thiol compound having two or more thiol groups, 20%-79.9% by weight, based on the total weight of the composition, of a compound having two or more carbon-carbon double bonds and 0.1%-10% by weight, based on the total weight of the composition, of a separating agent having an alkyl radical having 4-20 carbon atoms, where the alkyl radical is unsubstituted or fluorine-substituted and the alkyl radical is bonded to a functional group. Also provided are the use of this lacquer composition as a protective lacquer on an optical surface of an optical element in the production of the optical element, and an optical element comprising the protective lacquer.