Polarizing Plate Hydrogen-Bond Stabilization for Curling
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Solution Overview
Problem
Existing polarizing plates for liquid crystal display devices suffer from reduced durability and increased curling under high temperature and high humidity environments, leading to warping and distortion of the liquid crystal panel, which results in display unevenness.
Innovation Solution
A polarizing plate configuration with a polarizer and protective films containing a compound with a hydrogen-donating group capable of forming hydrogen bonds, having a molecular weight to aromatic ring ratio of 300 or less, is used to stabilize the iodine complex and maintain boric acid content, thereby reducing curling and improving durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the polarizing plate is used under high temperature and high humidity environments, then the polarizing plate provides initial polarization function, but the crossed transmittance significantly reduces and polarizer durability deteriorates over time
Solution Approach 1:
A water vapor barrier layer is introduced as an intermediary between the polarizing plate and the high humidity environment. This layer has water vapor permeability of 1×10^-11 to 1×10^-18 g·m/(m2·s·Pa), which is significantly lower than conventional protective films, thereby blocking water vapor penetration and preventing the degradation of the iodine complex and boric acid in the polarizer during long-term exposure to high temperature and high humidity conditions.
2Shape
If the polarizing plate thickness is reduced to decrease curling, then the dimensional stability improves, but the polarizing plate becomes more susceptible to environmental degradation
Solution Approach 1:
The patent employs a thin water vapor barrier layer (3 μm to 40 μm) that provides effective environmental protection despite its minimal thickness. This thin film structure reduces overall polarizing plate thickness and curling while maintaining sufficient barrier functionality against water vapor, thus resolving the contradiction between thickness reduction for curling control and protection capability.
Solution Approach 2:
The protective film is constructed as a composite material system combining a water vapor barrier layer with specific resin components (cellulose acylate, acrylic resin, or polycarbonate resin) and additives. This composite structure achieves both mechanical flexibility for curling control and chemical resistance for durability protection under high temperature and high humidity conditions.
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 maintains polarizer durability and prevents curling, ensuring stable display performance even under high temperature and high humidity conditions by stabilizing the iodine complex and reducing boric acid loss.
Implementation Method 1
contains a compound having at least one hydrogen-donating group capable of forming a hydrogen bond
Implementation Method 2
having a water vapor permeability of 1×10^-11 g·m/(m2·s·Pa) or less
Data Source
AI summary
A polarizing plate includes two protective films and a polarizer provided between the two protective films, and the polarizer has a thickness of 3 μm to 18 μm, at least one of the protective films has a thickness of 3 μm to 40 μm and contains at least one resin and a compound in an amount of 1 part by mass to 20 parts by mass based on 100 parts by mass of the resin, the compound having at least one hydrogen-donating group capable of forming a hydrogen bond and a ratio of molecular weight to number of aromatic rings of 300 or less, and the polarizing plate has a thickness of 15 μm to 70 μm.