Monolayered Acrylic Adhesive Resin Layer for Level Difference Substrates

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Solution Overview

Problem

Existing adhesive resin technologies fail to prevent air bubble generation when applied to substrates with level differences, leading to reduced adhering strength and optical properties, and are often costly with complex layer configurations.

Innovation Solution

A monolayered adhesive resin layer composed of an acrylic-based polymer, a hydroxyl-group containing acrylic monomer, and a thermopolymerization initiator, which is thermally cured at 100-250°C, providing pressure-sensitive adhesiveness and excellent followability to substrates with level differences without generating air bubbles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a pressure sensitive adhesive agent is laminated on a substrate having a level difference, then adhesion is achieved, but air bubbles are generated and adhering strength is reduced

Engineering Contradiction:
Improveadhering strengthVSAvoidair bubbles
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The adhesive resin composition changes its viscosity parameter in response to temperature changes. At application temperature, the adhesive has low viscosity to flow into level differences and prevent air bubbles. Upon heating, the viscosity increases to maintain the filled shape and provide strong adhesion.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The adhesive resin transitions from a dynamic, flowable state during application to a static, rigid state after heating. This dynamic behavior allows the adhesive to adapt to substrate irregularities and then maintain structural integrity.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If a pressure sensitive adhesive sheet with multiple layers is used to improve followability to level differences, then adhesion is improved, but device complexity and cost increase

Engineering Contradiction:
Improvefollowability to level differencesVSAvoidlayer configuration
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention merges multiple functions into a single adhesive resin layer. The adhesive layer simultaneously provides followability to level differences, prevents air bubble generation, and delivers strong adhesion after heating, eliminating the need for separate hard coat layers, multiple adhesive layers, and release sheets.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single adhesive resin layer performs multiple functions: it acts as the adhesive layer, the hard coat layer, and the release sheet equivalent. This multi-functional design simplifies the overall structure while maintaining all necessary performance characteristics.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Productivity

If a photopolymerization-based adhesive is used to achieve fast curing, then productivity is improved, but air bubbles are generated when applied to substrates with level differences

Engineering Contradiction:
Improvecuring speedVSAvoidair bubbles
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The invention replaces photopolymerization with thermal polymerization. The thermal curing process allows the adhesive to remain flowable during application to fill level differences, then cures upon heating to prevent air bubbles and provide strong adhesion, unlike photopolymerization which cures too quickly.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Stability of the object's composition

If an adhesive resin with high viscosity is used to maintain shape, then structural stability is improved, but followability to level differences deteriorates

Engineering Contradiction:
Improveshape stabilityVSAvoidfollowability to level differences
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The adhesive resin's viscosity parameter is dynamically changed through temperature control. During application at ambient temperature, the adhesive has low viscosity to flow and follow level differences. After heating, the viscosity increases to maintain shape stability and prevent air bubbles.

Inventive Principle:
Principle #35Parameter changes

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 effectively prevents air bubble formation and maintains transparency, ensuring strong adhesion and durability even on substrates with high level differences, while simplifying the layer configuration and reducing costs.

Implementation Method 1

the adhesive resin layer has pressure sensitive adhesiveness on both surfaces at an ambient temperature, and can be thermally cured by heating at a temperature of 100 to 250°C and a time of 30 seconds to 10 minutes

Methodology Applied
Scientific EffectThermopolymerization: Photopolymerisation

Implementation Method 2

the adhesive resin layer has pressure sensitive adhesiveness on both surfaces at an ambient temperature

Methodology Applied
Scientific EffectPressure-sensitive adhesion: Adhesive

Implementation Method 3

can be thermally cured by heating at a temperature of 100 to 250°C and a time of 30 seconds to 10 minutes

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3252121B1Adhesive resin layer, adhesive resin film, laminate, and laminate manufacturing method
Publication Date: 2022.12.14 FUJIMORI KOGYO CO LTD
  • EP3252121B1 patent drawingFigure 1~3
  • EP3252121B1 patent drawingFigure 4~5
  • EP3252121B1 patent drawing

AI summary

The present invention provides an adhesive resin layer, which can prevent generation of air bubbles even when adhered to a substrate having a high level difference, and can maintain transparency, an adhesive resin film, a laminate, and a method of producing a laminate. More specifically, the present invention is a monolayered adhesive resin layer comprising an acrylic-based adhesive resin composition having transparency, wherein the adhesive resin composition contains (A) an acrylic-based polymer, (B) an acrylic-based monomer, and (C) a thermopolymerization initiator, and an adhesive resin layer 11 has pressure sensitive adhesiveness on both surfaces 11a, 11b at an ambient temperature, and can be thermally cured by heating at a temperature of 100 to 250°C and a time of 30 seconds to 10 minutes.