Transparent Resin Composition for Bright Vehicle Lamp Covers

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Solution Overview

Problem

Existing transparent resin compositions for vehicle lamp covers fail to achieve an optimal balance between transparency and brightness, particularly when used in curved surfaces, due to issues with titanium dioxide content, particle diameter distribution, and refractive index differences, leading to insufficient brightness and yellowish tint.

Innovation Solution

A transparent resin composition with a specific range of titanium dioxide content (6.5 to 18 mass ppm) and particle diameter (220 to 280 nm) is used, combined with a refractive index difference of 0.3 to 3.0, to enhance transparency, brightness, and reduce coloring, suitable for lamp covers with curved surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the transparency of the resin is increased, then the light scattering is reduced and the material becomes more transparent, but the brightness emission decreases

Engineering Contradiction:
ImprovebrightnessVSAvoidtitanium dioxide content
Core Design Contradiction:
Illumination intensityVSQuantity of substance

Solution Approach 1:

The patent optimizes the particle diameter of titanium dioxide to a specific range (220-280 nm) and controls its content (6.5-18 mass ppm) to achieve the desired balance between transparency and brightness. By changing these parameters within specific ranges, the invention resolves the contradiction between high transparency and high brightness emission.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies light diffusing agents with specific local properties (particle diameter 220-280 nm, specific refractive index) at controlled concentrations (6.5-18 mass ppm) to create regions of optimal light diffusion. This localized optimization of material properties allows the resin to maintain both high transparency and high brightness emission simultaneously.

Inventive Principle:
Principle #3Local quality

2Illumination intensity

If titanium dioxide content is increased to improve brightness, then the brightness emission increases, but the transparency decreases and yellowish tint appears

Engineering Contradiction:
ImprovebrightnessVSAvoidyellowish tint
Core Design Contradiction:
Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The patent specifies a narrow optimal range for titanium dioxide content (6.5-18 mass ppm) and particle diameter (220-280 nm) to prevent yellowish tint while maintaining brightness. By controlling these parameters within specific ranges, the invention eliminates the harmful yellowish discoloration effect that occurs with higher titanium dioxide content.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite resin material containing transparent resin and light diffusing agents (titanium dioxide) in optimized proportions (6.5-18 mass ppm). This composite structure achieves high brightness emission while preventing the yellowish tint that would occur with higher concentrations of titanium dioxide.

Inventive Principle:
Principle #40Composite materials

3Illumination intensity

If the particle diameter of titanium dioxide is decreased to improve transparency, then the transparency increases, but the brightness emission becomes insufficient

Engineering Contradiction:
ImprovebrightnessVSAvoidparticle diameter control
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent identifies and controls the critical parameter of titanium dioxide particle diameter within a specific range (220-280 nm). By maintaining this precise parameter range, the invention achieves both high transparency and sufficient brightness emission, resolving the contradiction between these two properties.

Inventive Principle:
Principle #35Parameter changes

4Adaptability or versatility

If the light guiding distance is extended to increase the size of vehicle members, then the design flexibility increases, but the brightness maintenance becomes difficult

Engineering Contradiction:
Improvedesign flexibilityVSAvoidbrightness
Core Design Contradiction:
Adaptability or versatilityVSIllumination intensity

Solution Approach 1:

The patent incorporates light diffusing agents with specific local properties (particle diameter 220-280 nm, refractive index difference 0.3-3.0) at controlled concentrations (6.5-18 mass ppm) throughout the resin. This localized optimization of light diffusion properties enables the resin to maintain high brightness emission even over extended light guiding distances, providing design flexibility for larger vehicle members.

Inventive Principle:
Principle #3Local quality

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 resin composition provides high brightness when illuminated and low visibility when off, maintaining an excellent balance between transparency and brightness, suitable for vehicle lamp covers and other applications.

Implementation Method 1

the higher the transparency of a material is, the less likely it is that incident light will be scattered and the more the brightness tends to decrease

Methodology Applied
Scientific EffectLight scattering: Scattering

Data Source

PatentEP3763994B1Transparent resin composition, resin molded body, lamp cover, lamp cover for vehicles, combination lamp cover, and vehicle
Publication Date: 2026.04.22 MITSUBISHI CHEM CORP
  • EP3763994B1 patent drawingFigure 1~2
  • EP3763994B1 patent drawingFigure 3A~3B
  • EP3763994B1 patent drawingFigure 4~5

AI summary

A transparent resin composition includes a transparent resin and a light diffusing agent which has an average particle diameter of 220 nm or more and 300 nm or less, in which a content proportion of the light diffusing agent is more than 4.0 mass ppm and less than 20 mass ppm with respect to the total mass of the transparent resin composition.