Laminate with Low Moisture Permeability for Display Discoloration
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Solution Overview
Problem
Existing image display devices face challenges in maintaining excellent display performance and discoloration resistance, particularly when using polarizer layers with azo coloring agents, due to moisture permeability issues and the degradation of these layers over time.
Innovation Solution
A laminate comprising two substrates with low moisture permeability, a polarizer layer containing azo coloring agents with two or more azo bonds, and a pressure sensitive adhesive layer, where the moisture content between the substrates is controlled to minimize discoloration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a polarizer layer containing azo coloring agents is used in image display devices, then display performance is improved, but discoloration occurs over time due to moisture permeability issues
Solution Approach 1:
The patent uses a composite laminate structure consisting of multiple layers including substrates, polarizer layers containing azo coloring agents, and pressure-sensitive adhesive layers. This composite structure allows the different materials to work together - the substrates provide structural support, the azo coloring agents provide optical functionality, and the adhesive layers bond the components while controlling moisture transmission, thereby achieving both display performance and discoloration resistance
Solution Approach 2:
The patent specifies precise parameter ranges to prevent discoloration: moisture content between substrates is controlled to be 0.9 g/m2 or less, moisture permeability is limited to 10−3 g/m2·day or less, and azo coloring agents must have two or more azo bonds per molecule. By controlling these parameters, the patent maintains the optical properties of the azo coloring agents while preventing moisture-induced degradation
2Ease of manufacture
If moisture permeability of substrates is high, then manufacturing is easier, but moisture content increases causing polarizer layer degradation
Solution Approach 1:
The patent creates a low-moisture environment between the substrates by specifying substrates with moisture permeability of 10−3 g/m2·day or less and controlling moisture content to 0.9 g/m2 or less. This inert, low-moisture environment protects the moisture-sensitive azo coloring agents and pressure-sensitive adhesive layers from degradation, maintaining polarizer layer stability without complicating manufacturing
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 laminate achieves excellent display performance and enhanced discoloration resistance for image display devices, by effectively managing moisture levels and stabilizing the polarizer layer.
Implementation Method 1
the polarizer layer contains one or more kinds of azo coloring agents having two or more azo bonds in a molecule
Implementation Method 2
moisture permeabilities of the two substrates are 10−3 g/m2·day or less
Data Source
AI summary
An object of the present invention is to provide a laminate capable of preparing an image display device having excellent display performance and excellent discoloration resistance, and an image display device formed of the laminate. The laminate of the present invention is a laminate including two substrates, and a polarizer layer disposed between the two substrates, in which the polarizer layer contains one or more kinds of azo coloring agents having two or more azo bonds in a molecule, moisture permeabilities of the two substrates are 10−3 g/m2·day or less, and a content of moisture present between the two substrates is 0.9 g/m2 or less.