Photosensitive Resin Protective Film for Capacitive Touch Panels

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing protective films for capacitive touch panels face issues with wet heat resistance after salt water exposure and surface defects such as swelling or depression, with known technologies either compromising on wet heat resistance or surface quality.

Innovation Solution

A transfer film comprising a temporary support and a photosensitive transparent resin layer with a binder polymer, ethylenically unsaturated compound, photopolymerization initiator, and a compound capable of reacting with acid due to heating, featuring a blocked isocyanate compound and a second transparent resin layer with a higher refractive index, which forms a protective film with improved wet heat resistance and surface shape.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protective film is formed using conventional photosensitive resin composition, then the electrode patterns are protected, but wet heat resistance deteriorates after salt water exposure

Engineering Contradiction:

Improvewet heat resistanceVSAvoidsalt water exposure damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the chemical composition parameters of the photosensitive resin by incorporating specific compounds (blocked isocyanate compound, carboxyl group-containing compound, and silane compound) that react upon heating to form a crosslinked structure. This parameter change in the resin composition enables the cured film to achieve excellent wet heat resistance after salt water exposure while maintaining protective functions.

Inventive Principle:

Principle #35Parameter changes

2Strength

If a protective film is formed with sufficient thickness to ensure protection, then rust inhibiting properties improve, but surface defects such as swelling or depression occur

Engineering Contradiction:

Improverust inhibiting propertiesVSAvoidsurface defects

Core Design Contradiction:

StrengthVSShape

Solution Approach 1:

The patent creates a composite cured film by combining multiple functional compounds (blocked isocyanate, carboxyl group-containing compound, silane compound, and photopolymerizable compound) within the photosensitive resin matrix. This composite structure provides both adequate thickness for rust protection and uniform curing characteristics that prevent surface defects like swelling or depression.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the thickness and composition parameters of the protective film to achieve a balance between protection and surface quality. By controlling the film thickness within a specific range and adjusting the composition of reactive compounds, the cured film attains sufficient rust inhibiting properties while maintaining a smooth, defect-free surface.

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If transparent electrode patterns are made more concealing, then appearance quality improves, but light transmittance decreases

Engineering Contradiction:

Improveconcealing propertiesVSAvoidlight transmittance

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The patent adjusts the refractive index parameter of the cured protective film by selecting appropriate resin components and their ratios. This parameter optimization enhances the concealing properties of the transparent electrode patterns, making them less visually recognizable, while maintaining sufficient light transmittance for touch panel operation.

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 provides a protective film with enhanced wet heat resistance and surface quality, preventing defects like swelling and depression, while maintaining transparency and concealing properties of the capacitive touch panel electrodes.

Implementation Method 1

a photopolymerization initiator, and blocked isocyanate... curing a predetermined portion of the photosensitive layer by emitting an actinic ray

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

a compound capable of reacting with acid due to heating... featuring a blocked isocyanate compound

Methodology Applied

Scientific EffectThermal reaction: Heating

Data Source

PatentUS11762291B2Transfer film, electrode protective film, laminate, capacitive input device, and manufacturing method of touch panel

Publication Date: 2023.09.19 FUJIFILM CORP

AI summary

A transfer film includes a temporary support; and a photosensitive transparent resin layer positioned on the temporary support, in which the photosensitive transparent resin layer includes a binder polymer, an ethylenically unsaturated compound, a photopolymerization initiator, and a compound capable of reacting with acid due to heating, and the compound capable of reacting with acid due to heating includes a polymerizable group. In addition, an electrode protective film using the transfer film, a laminate, a capacitive input device, and a manufacturing method of a touch panel are provided.