Coating composition having infrared reflective function, coating glass and method for preparation thereof, and cooking appliance using same

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Solution Overview

Problem

Existing infrared reflective coating layers on cooking appliance door glass suffer from degradation due to high heat exposure, leading to reduced reflection efficiency, high costs, low light transmittance, and difficulty in cleaning, especially when exposed to contaminants.

Innovation Solution

A coating composition comprising 20-40 wt% phosphorus pentoxide, 15-30 wt% aluminum oxide and zirconium dioxide, 10-30 wt% sodium and potassium oxide, 10-25 wt% boron trioxide, 10-15 wt% zinc oxide, and 5-10 wt% heat conductive oxide nano powder, applied at a calcination temperature of 700°C or lower, providing high light transmittance and improved cleaning performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an infrared reflective coating layer including titanium and tin is used, then the infrared reflective function is improved, but the coating layer experiences oxidation and degradation when exposed to high heat, reducing reflection efficiency

Engineering Contradiction:
Improveinfrared reflective functionVSAvoidcoating layer stability under heat
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical composition parameters of the coating layer by replacing traditional titanium and tin oxides with a new formulation consisting of zinc oxide (10-20 wt%), boron oxide (15-25 wt%), phosphorus pentoxide (10-20 wt%), and silicon oxide (5-15 wt%). This compositional parameter change enables the coating to maintain infrared reflective function while achieving high thermal stability and resistance to oxidation at elevated temperatures.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite coating material by combining multiple oxide components (zinc oxide, boron oxide, phosphorus pentoxide, and silicon oxide) in specific proportions. This composite formulation synergistically provides infrared reflectivity, thermal stability, and oxidation resistance, overcoming the limitations of single-component or traditional multi-component coatings.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If a coating layer is applied to block infrared radiation, then user safety is improved, but the light transmittance decreases making it difficult for users to see into the cooking appliance

Engineering Contradiction:
Improveinfrared radiation blockingVSAvoidlight transmittance
Core Design Contradiction:
Object-affected harmful factorsVSIllumination intensity

Solution Approach 1:

The patent applies local quality by designing a coating with spatially selective optical properties. The coating layer is formulated to selectively reflect infrared radiation while maintaining high transparency in the visible light range. This is achieved through the specific composition of oxide materials and their controlled distribution, allowing different spectral regions to be treated differently within the same coating structure.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent utilizes optical property modulation by controlling the refractive indices and absorption characteristics of the oxide components. The coating is designed to be optically transparent in the visible range while exhibiting high reflectivity in the infrared range, effectively creating a spectrally selective coating that appears transparent to users but blocks harmful infrared radiation.

Inventive Principle:
Principle #32Color changes

3Reliability

If traditional coating materials are used, then the infrared reflective function is achieved, but the unit cost of the coating layer becomes high

Engineering Contradiction:
Improveinfrared reflective functionVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive traditional infrared reflective materials (titanium oxide and tin oxide) with more cost-effective oxide materials such as zinc oxide, boron oxide, phosphorus pentoxide, and silicon oxide. These alternative materials are generally more abundant and less expensive while providing equivalent or superior performance in infrared reflection and thermal stability, thereby reducing the unit cost of the coating layer.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Object-generated harmful factors

If the coating layer is exposed to high temperature for cleaning, then contaminants are removed, but the door glass cannot be cleaned and the coating may degrade

Engineering Contradiction:
Improvecontaminant removalVSAvoidcoating integrity
Core Design Contradiction:
Object-generated harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent incorporates heat-resistant oxide materials (particularly boron oxide and silicon oxide) that form a thermally stable glassy matrix before exposure to cleaning temperatures. This pre-formed stable structure acts as a protective cushion that prevents coating degradation during high-temperature cleaning processes, allowing contaminants to be removed without damaging the coating integrity.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 coating composition maintains high light transmittance, enhances infrared reflective function, and facilitates easy cleaning at low temperatures, reducing manufacturing costs and improving user safety by preventing overheating.

Implementation Method 1

a heat conductive oxide nano powder, applied at a calcination temperature of 700°C or lower

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

coating composition having infrared reflective function

Methodology Applied
Scientific EffectInfrared reflection: Reflection

Data Source

PatentEP3771697A1Coating composition having infrared reflective function, coating glass and method for preparation thereof, and cooking appliance using same
Publication Date: 2021.02.03 LG ELECTRONICS INC
  • EP3771697A1 patent drawingFigure 1
  • EP3771697A1 patent drawingFigure 2
  • EP3771697A1 patent drawing

AI summary

A coating composition, coating glass and a method for preparation thereof, and a cooking appliance including the coating class are described. The coating composition includes a coating material and a heat conductive oxide nano powder that is 5 to 10 wt% with respect to a weight of the coating material. The coating composition provides an excellent infrared reflective function, a high transmittance, and an excellent cleaning performance.