Multilayer Optical Relief Adhesion via Segmented Resin Layers

Solution Overview

Problem

Optical reliefs produced by the photopolymerization method using radiation curable resins exhibit poor adhesion to reflection layers due to volume contraction during curing, leading to potential adhesion failure.

Innovation Solution

A multilayer relief structure is introduced, comprising a first resin layer made of non-radiation curable resin and a second resin layer made of radiation curable resin, with the first resin layer having a thickness smaller than the unevenness difference of the optical relief, enhancing adhesion to the reflection layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the photopolymerization method using radiation curable resin is used to produce optical relief, then high molding accuracy and good heat resistance are achieved, but poor adhesion to reflection layer occurs due to volume contraction during curing

Engineering Contradiction:

Improvemolding accuracyVSAvoidadhesion to reflection layer

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The optical relief is divided into two separate resin layers: a first resin layer made of non-radiation curable resin that contacts the reflection layer, and a second resin layer made of radiation curable resin that provides high molding accuracy. This segmentation allows each layer to perform its specialized function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first resin layer made of non-radiation curable resin acts as an intermediary layer between the reflection layer and the second resin layer. This intermediate layer prevents direct contact between the shrinking second resin layer and the reflection layer, thereby eliminating the adhesion failure caused by volume contraction during curing.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If radiation curable resin is used for optical relief, then high molding accuracy is achieved, but distortion stress remains at interface causing adhesion failure

Engineering Contradiction:

Improvemolding accuracyVSAvoidadhesion strength at interface

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The optical relief is divided into two separate resin layers: a first resin layer made of non-radiation curable resin that contacts the reflection layer, and a second resin layer made of radiation curable resin that provides high molding accuracy. This segmentation allows each layer to perform its specialized function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first resin layer made of non-radiation curable resin acts as an intermediary layer between the reflection layer and the second resin layer. This intermediate layer prevents direct contact between the shrinking second resin layer and the reflection layer, thereby eliminating the adhesion failure caused by volume contraction during curing.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If non-radiation curable resin is used for optical relief, then good adhesion to reflection layer is achieved, but heat resistance deteriorates

Engineering Contradiction:

Improveadhesion to reflection layerVSAvoidheat resistance

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The optical relief is divided into two separate resin layers: a first resin layer made of non-radiation curable resin that contacts the reflection layer, and a second resin layer made of radiation curable resin that provides high molding accuracy. This segmentation allows each layer to perform its specialized function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The optical relief is constructed as a composite structure combining two different resin materials, each selected for its specific advantages. The non-radiation curable resin provides adhesion, while the radiation curable resin provides heat resistance and molding accuracy, creating a composite material system that exhibits both properties simultaneously.

Inventive Principle:

Principle #40Composite materials

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 proposed solution achieves high molding accuracy, good heat resistance, and improved adhesion between the optical relief and the reflection layer, effectively addressing the adhesion issues of traditional photopolymerization methods.

Implementation Method 1

a radiation curable resin to be cured by irradiation with radiation in a broad sense, such as ultraviolet light (UV) or electron beams (EB), is poured into the space between an optical relief duplication mold and a flat substrate such as a plastic film, and the radiation curable resin is cured by irradiation

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS12287451B2Optical structure, transfer foil, article, and method of producing optical structure

Publication Date: 2025.04.29 TOPPAN HOLDINGS INC

AI summary

An optical structure includes a multilayer relief that has a first surface having an uneven shape, and a reflection layer that is formed on the first surface and reflects visible light. The multilayer relief includes a first resin layer that contains a non-radiation curable resin as a main component and constitutes the first surface, and a second resin layer that contains a radiation curable resin as a main component and is adjacent to the first resin layer. The first resin layer has a thickness smaller than an unevenness difference of the uneven shape.