Photocatalyst Coating Composition for Organic Substrate Protection
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Solution Overview
Problem
Conventional photocatalyst-coated bodies face issues with weather resistance, noxious gas decomposability, and substrate corrosion, particularly when using organic substrates, due to the photocatalytic activity of titanium oxide.
Innovation Solution
A photocatalyst-coated body is developed with a specified composition comprising photocatalyst particles and inorganic oxide particles in a specific mass ratio, minimizing hydrolyzable silicone and surfactant content, which enhances weather resistance, noxious gas decomposability, and coating properties while preventing substrate corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photocatalyst layer is applied directly on an organic substrate, then substrate corrosion occurs due to photocatalytic activity, but adding an intermediate adhesive layer increases manufacturing complexity and cost
Solution Approach 1:
The patent utilizes the photocatalytic activity of titanium oxide to decompose organic materials beneficially - specifically decomposing noxious gases and organic contaminants on the substrate surface, while the inorganic oxide particles protect the substrate from harmful photocatalytic degradation. This converts the potentially harmful photocatalytic effect into a beneficial cleaning and protective function.
Solution Approach 2:
The patent creates a composite photocatalyst layer combining titanium oxide particles (photocatalyst) with inorganic oxide particles (protective matrix). This composite structure allows the layer to simultaneously exhibit photocatalytic activity for decomposing pollutants while the inorganic oxide matrix prevents direct contact between the photocatalyst and organic substrate, eliminating the need for separate adhesive layers.
2Ease of manufacture
If hydrolyzable silicone and surfactant are added to improve coating properties, then coating performance improves, but weather resistance and noxious gas decomposability deteriorate
Solution Approach 1:
The patent optimizes the composition parameters of the photocatalyst layer by strictly controlling the content of hydrolyzable silicone and surfactant to be 10 mass % or less of the total coating composition. This parameter control ensures that the coating maintains sufficient applicability and surface properties while preventing excessive amounts of these additives from interfering with the photocatalytic decomposition of noxious gases and reducing weather resistance.
Solution Approach 2:
The patent applies different functional requirements to different components: hydrolyzable silicone and surfactant are permitted only in limited amounts (≤10 mass %) to provide localized coating benefits such as surface wetting and initial adhesion, while the majority composition (≥90 mass %) consists of photocatalyst and inorganic oxide particles that provide the primary functions of noxious gas decomposition and weather resistance.
3Reliability
If photocatalyst particles are increased to improve noxious gas decomposability, then decomposition efficiency improves, but substrate corrosion increases
Solution Approach 1:
The patent converts the harmful photocatalytic effect that causes substrate corrosion into a beneficial effect by using inorganic oxide particles as a protective barrier. The titanium oxide photocatalyst particles decompose noxious gases on the substrate surface, while the inorganic oxide particles prevent direct contact between the photocatalyst and the organic substrate, thus protecting it from degradation.
Solution Approach 2:
The patent creates a composite structure where titanium oxide particles (photocatalyst) are combined with inorganic oxide particles (protective matrix). This composite allows high concentrations of photocatalyst (up to 90 mass % or more) to be used for effective noxious gas decomposition while the inorganic oxide component prevents substrate corrosion by acting as a physical barrier.
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 achieves superior weather resistance, noxious gas decomposability, and coating properties while minimizing substrate corrosion, allowing for a photocatalyst layer to be applied directly on organic substrates without an intermediate layer, reducing manufacturing costs and time.
Implementation Method 1
Employment of the photocatalyst makes it possible to harness light energy to decompose various types of noxious substances
Implementation Method 2
The inorganic oxide particles have an action of absorbing an ultraviolet ray and preventing deterioration of an organic material
Data Source
AI summary
A photocatalyst-coated body comprises a substrate and a photocatalyst layer provided on the substrate, the photocatalyst layer comprising photocatalyst particles of 1 part or more by mass and less than 20 parts by mass, inorganic oxide particles of 70 parts or more by mass and less than 99 parts by mass, and the dried substance of a hydrolyzable silicone of zero parts or more by mass and less than 10 parts by mass, provided that a total amount of the photocatalyst particles, the dried substance of the inorganic oxide particles and the hydrolyzable silicone is 100 parts by mass in terms of silica. The inorganic oxide particles have a number average particle diameter ranging from 10 nm or more to less than 40 nm calculated by measuring lengths of 100 particles randomly selected from particles located within a visible field magnified 200,000 times by a scanning electron microscope.