Polycarbonate Light Diffusion Sheet Resolving Transmittance Trade-off

Solution Overview

Problem

Typical light diffusion sheets for lighting applications face limitations due to a decrease in light transmittance with increasing light spreading, necessitating a thermoplastic resin composition that balances light transmission and diffusion effectively.

Innovation Solution

A thermoplastic resin composition comprising 100 parts by weight of polycarbonate resin and 0.5 to 3 parts by weight of polystyrene-poly(methyl methacrylate) copolymer particles, with specific weight percentages and particle size distributions, is used to create a light diffusion sheet with improved transmittance and diffusion properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the degree of light spreading is increased in a typical light diffusion sheet, then light diffusion is improved, but light transmittance decreases

Engineering Contradiction:

Improvelight diffusionVSAvoidlight transmittance

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent applies parameter changes by precisely controlling the particle size distribution (D10-D90 range of 20-50 μm with specific D50 values) and composition ratios (polystyrene 30-70 wt%, poly(methyl methacrylate) 30-70 wt%) of the copolymer particles. These parameter optimizations enable the light diffusion sheet to achieve both high light diffusion (luminosity angle 10-30 degrees) and high light transmittance (90-98%), resolving the technical contradiction between light spreading and light transmission.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining polycarbonate resin with polystyrene-poly(methyl methacrylate) copolymer particles in specific ratios (0.1-5 parts by weight per 100 parts of polycarbonate). This composite structure allows the material to simultaneously provide the transparency and formability of polycarbonate while incorporating the light diffusion properties of the copolymer particles, achieving both high light transmittance and effective light diffusion.

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If a polycarbonate resin with silicone or acrylic light diffusing agent is used, then light diffusion is improved, but the balance between light transmission and diffusion is insufficient

Engineering Contradiction:

Improvelight diffusionVSAvoidbalance between light transmission and diffusion

Core Design Contradiction:

Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by precisely controlling the particle size distribution (D10-D90 range of 20-50 μm with specific D50 values) and composition ratios (polystyrene 30-70 wt%, poly(methyl methacrylate) 30-70 wt%) of the copolymer particles. These parameter optimizations enable the light diffusion sheet to achieve both high light diffusion (luminosity angle 10-30 degrees) and high light transmittance (90-98%), resolving the technical contradiction between light spreading and light transmission.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining polycarbonate resin with polystyrene-poly(methyl methacrylate) copolymer particles in specific ratios (0.1-5 parts by weight per 100 parts of polycarbonate). This composite structure allows the material to simultaneously provide the transparency and formability of polycarbonate while incorporating the light diffusion properties of the copolymer particles, achieving both high light transmittance and effective light diffusion.

Inventive Principle:

Principle #40Composite materials

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 composition achieves transmittance of 96% or more and luminosity angles of 3° to 30°, maintaining a balance between light transmission and diffusion, enhancing the performance of light diffusion sheets for lighting applications.

Implementation Method 1

a light diffusion sheet for lighting produced therefrom... to disperse the light emitted from the LED... to improve dispersion of light

Methodology Applied

Scientific EffectLight scattering: Scattering

Data Source

PatentUS11518879B2Thermoplastic resin composition and light diffusion sheet produced therefrom

Publication Date: 2022.12.06 LOTTE CHEM CORP

AI summary

A thermoplastic resin composition comprises about 100 parts by weight of a polycarbonate resin; and about 0.5 parts by weight to about 3 parts by weight of polystyrene-poly(methyl methacrylate) copolymer particles, wherein the polystyrene-poly(methyl methacrylate) copolymer particles include about 41 wt % to about 59 wt % of polystyrene and about 41 wt % to about 59 wt % of poly(methyl methacrylate) and have an average particle diameter of about 3 μm to about 9 μm and a coefficient of variation (CV) of about 20% to about 40%. The thermoplastic resin composition can have good properties in terms of light transmission, light diffusion and balance therebetween.