Cationic Epoxy Resin Laser Curing Without Pigments

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Solution Overview

Problem

Conventional visible-laser-curable or infrared-laser-curable adhesives with added pigments suffer from uneven curing, surface burning, and deterioration of physical properties due to excessive energy absorption, making them unsuitable for delicate components like camera modules and electronic sensor assemblies.

Innovation Solution

A cationically polymerizable epoxy resin composition comprising an epoxy resin and an acid generator, which can be cured using visible or infrared lasers, reducing curing time and energy requirements without the need for pigments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If black pigments are added to absorb laser energy and promote curing, then curing is enhanced, but only the area around the pigment becomes extremely hot causing deterioration of physical properties and decomposition

Engineering Contradiction:
Improvecuring enhancementVSAvoidexcessive heat concentration
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes the black pigment from the adhesive composition, extracting the harmful energy-absorbing component that caused localized overheating. Instead, it uses a cationically polymerizable epoxy resin system that cures through a different mechanism without requiring heat-absorbing pigments, thereby eliminating the source of excessive heat concentration while maintaining effective curing.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the curing mechanism from thermal/photothermal (requiring heat absorption) to cationic polymerization initiated by acid generators. This parameter change in the chemical mechanism allows curing to proceed without concentrating heat at pigment locations, distributing the curing reaction more uniformly throughout the adhesive layer.

Inventive Principle:
Principle #35Parameter changes

2Strength

If high temperature curing (150°C or higher) is used, then bonding strength is improved, but optical components may deviate from predetermined positions and physical properties deteriorate

Engineering Contradiction:
Improvebonding strengthVSAvoidposition accuracy
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent changes the curing temperature parameter from high temperature (150°C or higher) to lower temperature curing enabled by cationic polymerization. The acid generator initiates polymerization at lower temperatures, providing sufficient bonding strength without the thermal stress that causes optical components to deviate from their predetermined positions.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If visible or infrared lasers are used for curing, then curing speed is improved, but excessive energy absorption causes surface burning and decomposition

Engineering Contradiction:
Improvecuring speedVSAvoidsurface burning
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent removes the pigment component that causes excessive energy absorption and surface burning. The cationically polymerizable epoxy resin system without pigments allows laser energy to be distributed more uniformly, enabling fast curing speeds without the harmful surface burning effect.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the laser energy that would otherwise be harmfully absorbed by pigments into useful cationic polymerization initiation. The acid generator captures the laser energy to initiate curing, transforming what would be harmful heat into beneficial chemical reaction initiation, thereby achieving fast curing without surface burning.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 composition enables efficient curing in a shorter time and with less energy, preventing surface burning and maintaining the integrity of the cured product, making it suitable for bonding in camera modules and electronic sensor assemblies.

Implementation Method 1

the acid generator is a photoacid generator or a thermal acid generator

Methodology Applied
Scientific EffectPhotoacid generation: Photopolymerisation

Implementation Method 2

the acid generator is a photoacid generator or a thermal acid generator

Methodology Applied
Scientific EffectThermal acid generation: Thermolysis

Implementation Method 3

a cationically polymerizable epoxy resin composition comprising (A) an epoxy resin and (B) an acid generator

Methodology Applied
Scientific EffectCationic polymerization: Photopolymerisation

Data Source

PatentUS20240093073A1Visible-Laser-Curable or Infrared-Laser-Curable Cationically Polymerizable Epoxy Resin Composition
Publication Date: 2024.03.21 HENKEL KGAA

AI summary

Provided is a visible-laser-curable or infrared-laser-curable resin composition that cures in a shorter time and with less energy. A visible-laser-curable or infrared-laser-curable cationically polymerizable epoxy resin composition comprising (A) an epoxy resin and (B) an acid generator.