Photocatalyst Layer Durability in Sanitary Ware

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Solution Overview

Problem

Sanitary ware photocatalyst layers with titanium oxide and zirconia compounds face durability issues when exposed to alternating acidic and alkaline pH conditions during cleaning, leading to peeling and loss of photocatalytic activity.

Innovation Solution

A photocatalyst layer comprising titanium oxide and zirconium oxide, with a specific ratio of 95-75% and 5-25% respectively, is combined with an intermediate layer containing silica and titanium oxide or zirconium oxide in a ratio of 98-85% and 2-15%, respectively, to enhance durability and prevent peeling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a photocatalyst layer comprising titanium oxide and zirconia compound is provided on the glaze layer surface, then photocatalytic activity and film strength are improved, but durability against alternating acidic and alkaline cleaning conditions deteriorates

Engineering Contradiction:
Improvephotocatalytic activityVSAvoiddurability against cleaning conditions
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

An intermediate layer comprising silica and titanium oxide/zirconium oxide is introduced between the glaze layer and the photocatalyst layer. This intermediate layer acts as a buffer that resists the impact of alternating acidic and alkaline cleaning conditions, protecting the photocatalyst layer from direct exposure to harsh pH environments while maintaining the photocatalytic activity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a composite structure consisting of three layers: the glaze layer, the intermediate layer (comprising silica and titanium oxide/zirconium oxide), and the photocatalyst layer (comprising titanium oxide and zirconium oxide). This composite structure combines the benefits of each layer to achieve both durability and photocatalytic activity.

Inventive Principle:
Principle #40Composite materials

2Strength

If firing is performed at high temperature (500-1000°C) to form a strong photocatalyst film, then film strength is improved, but alkali ions in the glaze disperse and photocatalytic activity deteriorates

Engineering Contradiction:
Improvefilm strengthVSAvoidphotocatalytic activity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The intermediate layer comprising silica and titanium oxide/zirconium oxide serves as a protective barrier during high-temperature firing. It prevents the dispersion of alkali ions from the glaze layer while allowing the formation of a strong photocatalyst film, thus maintaining both film strength and photocatalytic activity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent optimizes the composition ratios of the intermediate layer and photocatalyst layer to achieve the desired balance between film strength and photocatalytic activity. The intermediate layer contains silica (98-85 mass%) and titanium oxide/zirconium oxide (2-15 mass%), while the photocatalyst layer contains titanium oxide (95-75 mass%) and zirconium oxide (5-25 mass%).

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 durability of the photocatalyst layer, preventing peeling and maintaining photocatalytic activity even under alternating acidic and alkaline conditions, as demonstrated by prolonged resistance in acidity and alkalinity exposure tests.

Implementation Method 1

a sanitary ware having a photocatalytic surface layer formed on its surface is known. Such a sanitary ware can suppress sticking of filth thereto by virtue of hydrophilicity exhibited by irradiation of light, preferably ultraviolet light, on the photocatalyst layer and, at the same time, can suppress proliferation of bacteria by virtue of decomposition action by the photocatalyst

Methodology Applied
Scientific EffectPhoto-oxidation: Photo-oxidation

Data Source

PatentUS10010865B2Sanitary ware having photocatalyst layer
Publication Date: 2018.07.03 TOTO LTD

AI summary

Disclosed is a sanitary ware having a photocatalyst layer which has excellent durability even in an environment where the photocatalyst layer is exposed to an acid and an alkali alternately. The sanitary ware comprises a glaze layer, an intermediate layer provided on the glaze layer, and a photocatalyst layer provided on the intermediate layer, wherein the photocatalyst layer comprises titanium oxide in the amount of 95 mass % to 75 mass % and zirconium oxide in the amount of 5 mass % to 25 mass % and the intermediate layer comprises silica in the amount of 98 mass % to 85 mass %, and titanium oxide and/or zirconium oxide in the amount of 2 mass % to 15 mass %.