Aromatic Polycarbonate Resin Composition for Optical Light Guide Plates

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Solution Overview

Problem

Aromatic polycarbonate resin compositions for optical use face challenges in achieving high light transmittance and luminance while maintaining heat resistance, particularly when molded at elevated temperatures, leading to issues like yellowing and silver streaks, which restrict their application to small-sized light guide plates.

Innovation Solution

Incorporating a polyoxytetramethylene-polyoxyethylene glycol derivative and a combination of phosphoric and hindered phenolic antioxidants into the aromatic polycarbonate resin composition to enhance heat resistance and prevent oxidative degradation, allowing for molding at higher temperatures without compromising light transmittance and luminance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If polyoxyalkylene glycol is added to improve light transmittance and luminance, then optical performance is enhanced, but heat resistance deteriorates causing yellowing and silver streaks at molding temperatures exceeding 320°C

Engineering Contradiction:

ImproveluminanceVSAvoidheat resistance

Core Design Contradiction:

Illumination intensityVSTemperature

Solution Approach 1:

The invention changes the chemical structure parameter of the polyether component from conventional polyoxyalkylene glycol to a specific polyoxytetramethylene-polyoxyethylene glycol with defined molecular weight (1,000-5,000) and composition ratio (m:n = 1:1 to 4:1). This parameter change enables the material to maintain both improved optical performance and sufficient heat resistance for molding temperatures up to 340°C, resolving the contradiction between luminance enhancement and heat resistance preservation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite resin system combining aromatic polycarbonate with a specifically designed polyoxytetramethylene-polyoxyethylene glycol. This composite material leverages the light-transmitting properties of the polyether component while the aromatic polycarbonate matrix provides thermal stability, achieving both improved luminance and maintained heat resistance that neither component could achieve alone

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If molding temperature is increased to improve fluidity for large-area light guide plates, then manufacturing capability is enhanced, but decomposition gas causes silver streaks on the surface

Engineering Contradiction:

ImprovefluidityVSAvoidsilver streaks

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The invention modifies the molecular weight parameter of the polyether component to 1,000-5,000 and controls the m:n ratio between 1:1 to 4:1, which optimizes the resin's fluidity characteristics. This enables successful molding of large-area light guide plates at temperatures up to 340°C without generating decomposition gases that cause silver streaks, thus improving manufacturing capability while preventing surface defects

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If conventional aromatic polycarbonate is used for small-sized light guide plates at low temperature, then optical performance is maintained, but application range is limited

Engineering Contradiction:

Improveoptical performanceVSAvoidapplication range

Core Design Contradiction:

Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The invention introduces a polyether component with specifically controlled parameters (molecular weight 1,000-5,000, m:n ratio 1:1 to 4:1) into the aromatic polycarbonate system. This parameter modification maintains excellent optical performance while enabling processing at higher temperatures (up to 340°C) and longer molding cycles, thereby expanding the application range to include large-area light guide plates and other optical components that were previously inaccessible

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 significantly improves the heat resistance and optical performance of the resin, enabling the production of high-quality light guide plates with improved light transmittance and luminance, even at temperatures exceeding 340°C, thus expanding the practical use of aromatic polycarbonate resin compositions.

Implementation Method 1

Methodology Applied

Scientific EffectOxidative degradation: Oxidation

Implementation Method 2

molding at a temperature exceeding 320° C. or a long molding cycle causes severe yellowing

Methodology Applied

Scientific EffectThermal oxidation: Oxidation

Data Source

PatentUS9097838B2Aromatic polycarbonate resin composition and molded articles for optical use which are made using same

Publication Date: 2015.08.04 IDEMITSU KOSAN CO LTD

AI summary

Provided are an aromatic polycarbonate resin composition and molded articles for optical use using the same, the resin composition having improved light transmittance and luminance and, at the same time, being able to withstand molding even at a high temperature.More specifically, provided are the aromatic polycarbonate resin composition and molded articles for optical use using the same, the resin composition comprising 100 parts by mass of an aromatic polycarbonate resin (A) and 0.1 to 5 parts by mass of polyoxytetramethylene-polyoxyethylene glycol (B).