Polycarbonate Resin Composition for Light Guide Plate Transmittance

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Solution Overview

Problem

Polycarbonate resin compositions face challenges in achieving high light transmittance and heat resistance while maintaining mechanical strength and color stability, particularly in thin light guide plates used in liquid crystal display devices.

Innovation Solution

A polycarbonate resin composition combining 100 parts by weight of polycarbonate with 0.05 to 5 parts by weight of polyoxytetramethylene-polyoxypropylene glycol random copolymer and 0.001 to 5 parts by weight of a vinyl-based polymer containing a (meth)acrylate repeating unit with an epoxy functional group, enhancing light transmittance, heat resistance, and color stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If polycarbonate is used as light guide plate material, then mechanical strength and heat resistance are improved, but light transmittance deteriorates

Engineering Contradiction:

Improvemechanical strengthVSAvoidlight transmittance

Core Design Contradiction:

StrengthVSIllumination intensity

Solution Approach 1:

The patent applies composite materials by blending polycarbonate with PMMA (acrylic resin) to create a new material system that combines the high mechanical strength and heat resistance of polycarbonate with the high light transmittance of PMMA, thereby resolving the contradiction between strength and light transmittance

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the chemical composition parameters of the resin by controlling the ratio of polycarbonate to PMMA, and by selecting specific molecular weight ranges for both components, to optimize the balance between mechanical properties and optical properties

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If PMMA is used as light guide plate material, then light transmittance is improved, but mechanical strength and heat resistance deteriorate

Engineering Contradiction:

Improvelight transmittanceVSAvoidmechanical strength

Core Design Contradiction:

Illumination intensityVSStrength

Solution Approach 1:

The patent uses composite materials by combining PMMA with polycarbonate in specific ratios, where PMMA provides high light transmittance while polycarbonate contributes mechanical strength and heat resistance, thus overcoming the limitations of pure PMMA

Inventive Principle:

Principle #40Composite materials

3Temperature

If polycarbonate is used as light guide plate material, then heat resistance is improved, but light transmittance deteriorates

Engineering Contradiction:

Improveheat resistanceVSAvoidlight transmittance

Core Design Contradiction:

TemperatureVSIllumination intensity

Solution Approach 1:

The patent applies composite materials strategy by creating a blended resin system where polycarbonate provides heat resistance and PMMA provides high light transmittance, achieving simultaneous improvement in both thermal and optical performance

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP3165571B1Polycarbonate resin composition and optical molded article comprising same

Publication Date: 2020.06.17 LG CHEM LTD

AI summary

The present invention relates to a polycarbonate resin composition and an optical molded product comprising the same. The polycarbonate resin composition according to the present invention is excellent in transmittance and color uniformity which are required for a light guide plate, and also excellent in processability. Thus, it can be effectively used as a material of the light guide plate.