Transparent Composite Material Thermo-Optic Stability

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Solution Overview

Problem

Colorless composite materials made from glass fibers and typical transparent resins suffer from significant optical transmittance variations due to refractive index changes with temperature, leading to loss of transparency at different temperatures.

Innovation Solution

A colorless composite material is developed using glass fibers impregnated with an inorganic-organic hybrid resin, specifically formulated with Si-O-Si or Si-O-M bonds, where the metallic element can be Ti, Zr, or Al, and the ratio of inorganic bonds is adjusted to maintain a thermo-optic coefficient within -5 × 10^-5 °C to +10 × 10^-5 °C, achieved through a sol-gel method and heat or UV curing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If glass fibers are impregnated with typical transparent resin to create colorless composite material, then the material gains transparency and improved mechanical properties, but the optical transmittance varies significantly with temperature due to refractive index mismatch

Engineering Contradiction:
Improvemechanical propertiesVSAvoidoptical transmittance stability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent modifies the chemical composition parameters of the resin by incorporating inorganic components (silica, boron oxide) to adjust the refractive index. This changes the thermal-optical parameters of the resin so that its refractive index varies less with temperature, matching the glass fiber's refractive index across a wide temperature range and maintaining optical transmittance stability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a hybrid composite material system combining organic resin components with inorganic components (silica particles, boron oxide). This composite resin structure allows the material to exhibit both the mechanical properties of organic resins and the thermal-optical stability of inorganic materials, resolving the contradiction between mechanical strength and optical stability

Inventive Principle:
Principle #40Composite materials

2Illumination intensity

If the resin composition is adjusted to match refractive index at room temperature, then transparency is improved, but transparency is lost at different temperatures due to thermal expansion and refractive index changes

Engineering Contradiction:
ImprovetransparencyVSAvoidtemperature range stability
Core Design Contradiction:
Illumination intensityVSTemperature

Solution Approach 1:

The patent changes the thermal-optical parameters of the resin by adding inorganic components with low thermal expansion coefficients and stable refractive indices. The silica and boron oxide content is specifically controlled to ensure the resin's refractive index remains stable across temperature changes, maintaining transparency from -40°C to 80°C

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces inorganic particles and compounds at specific locations within the resin matrix to create localized regions with different thermal-optical properties. These inorganic phases act as refractive index stabilizers, ensuring that the overall material maintains consistent optical properties across temperature variations

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 material retains transparency and low haze over a wide temperature range, maintaining optical transmittance above 75% and haze below 15% from -10 °C to 80 °C, by aligning the thermo-optic coefficient of the resin with that of the glass fibers.

Implementation Method 1

a thermo-optic coefficient of the inorganic-organic hybrid resin may be -5 x 10^-5

Methodology Applied
Scientific EffectThermo-optic coefficient:

Implementation Method 2

achieved through a sol-gel method and heat or UV curing

Methodology Applied
Scientific EffectSol-gel method:

Implementation Method 3

manufacturing a colorless composite material by performing heat curing or UV curing for the impregnated materials

Methodology Applied
Scientific EffectUV curing: Photopolymerisation

Data Source

PatentEP2620468B1Transparent composite material and a production method therefor
Publication Date: 2020.07.15 LG ELECTRONICS INC
  • EP2620468B1 patent drawingFigure 1~2
  • EP2620468B1 patent drawingFigure 3

AI summary

This specification relates to a colorless composite material capable of retaining transparency within a wide temperature range by impregnating glass composition (glass fibers) with inorganic-organic hybrid resin. A colorless composite material according to exemplary embodiments includes glass fibers, and inorganic-organic hybrid resin consisting of inorganic bonds and organic bonds, wherein the inorganic bonds are Si-O-Si bonds or Si-O-M bonds and M denotes a metallic element.