Explanations of Expressions and Terms

Explanations of Expressions and Terms

(1) Terms Related to Light

a) Ultraviolet Light
The light that we are familiar with includes infrared, visible and ultraviolet light. The energy of violet visible light is higher than that of red visible light. The spectrum of light that contains higher energy than that of violet visible light is called "ultraviolet light." Artificial light sources emitting ultraviolet light that can be made use of by titanium dioxide photocatalyst are stipulated in JIS (Japanese Industrial Standard) R1709.
b) Sunlight
As evidenced by strong sunlight's tanning effects in summer, sunlight contains ultraviolet light. Titanium dioxide photocatalyst makes use of the ultraviolet light.

(2) Terms Related to Antibacterial Action

a) Antibacterial Protection
A state in which bacterial growths are curbed on product surfaces
b) Photocatalyst Antibacterial Treatment
Photocatalyst is supported through a variety of methods, including application, impregnation and kneading, in order to make use of its antibacterial function.
c) Antibacterial Effects
Test methods that judge whether photocatalyst antibacterial treatments are "antibacterial" are stipulated for plate-shaped and fibrous products respectively in JIS R1702. Antibacterial effects are judged based on "antibacterial activity values" that are found by the test methods. The relationship among the terms is shown in Table 1. In the same way, another test method that judges whether photocatalyst antibacterial treatments are "antifungal" is stipulated in JIS R1705.
d) Antibacterial Activity Values
Bacteria are inoculated on two products, one of which has received the photocatalyst antibacterial treatment and the other which has not, and the live bacterial numbers are measured after the products have been exposed to light. The antibacterial activity value is the difference between logarithmic values of the live bacterial numbers on the two products. This value includes decreases in bacterial numbers, which are obtained in conditions where the products are not exposed to light.
e) Effects of Light Exposure
Bacteria are inoculated on two plate-shaped products, and live bacterial numbers on the two products are measured after one of the products is exposed to light and the other is placed in a dark place. The light exposure effect is the difference between logarithmic values of the live bacterial numbers on the two products.
Table 1 Comparison of Terms Used for Plate-shaped and Fibrous Products
  Plate-shaped Products Fibrous Products Calculation Formulae
Antibacterial Activity Values Antibacterial activity value of a product with photocatalyst antibacterial treatment: R Bacteriostatic activity value of a fibrous product with photocatalyst antibacterial treatment: S Live bacterial numbers are measured after the products are exposed to light. The value is the difference between logarithmic values of the live bacterial numbers on two products, one of which has received the photocatalyst antibacterial treatment and the other which has not.
Effects of Light Exposure Light exposure effect on a product with photocatalyst antibacterial treatment: ΔR Light exposure effect on a fibrous product with photocatalyst antibacterial treatment: ΔS Live bacterial numbers are measured after the products are exposed to light. The value is the difference between logarithmic values of the live bacterial numbers on two products, one of which has received the photocatalyst antibacterial treatment and the other which has not.

(3) Terms Related to Self-Cleaning

a) Methods for Evaluating Self-Cleaning Performance
Test methods that evaluate the "phenomenon in which stains are dissolved" and "phenomenon in which stains are washed out" are stipulated in JIS R1703-2 (wet dissolution performance) and JIS R1703-1 (water contact angle measurement) respectively.
b) Hydrophilic Properties
Hydrophilic character of materials when water contacts the surface
c) Contact Angle
It is the angle between a tangential line on a curved surface of liquid placed on a horizontal solid matter and the surface of the solid matter. The contact angle of water is called "water contact angle."

(4) Terms Related to Air Purification

Test methods that evaluate performance in purifying air pollutants are stipulated for each target pollutant in JIS R1701-1 (NOx removal), JIS R1701-2 (acetaldehyde removal) and JIS R1701-3 (toluene removal).

(5) Terms Related to Water Purification

Test methods that evaluate performance in purifying aquatic pollutants by measuring active oxygen generation capacities are stipulated in JIS R1704 (DMSO dissolution).


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