Self-cleaning glass is a surface that has dust or stains that have a hard-to-bond dust on its glass surface or that is easy to clean. "Easy-clean glass" is also commonly referred to commercially as "self-clean glass" (Auto-clean glass). It refers to the application of a special coating on the surface of the glass, so that dust or dirty liquid (including water, even oily liquid) is difficult to adhere to the surface of the glass, or is easily washed away by water (or rain). This makes the glass surface very easy to keep clean, reduces the hassle of cleaning the glass surface, and saves water resources that are increasingly scarce.

This special coating is the so-called "easy clean coating" or "self-cleaning coating". It was developed using two basic physical features of objects in nature. The so-called easy-clean glass is the glass surface with high hydrophobicity and similar lotus effect, so that the water can not be completely adhered by the glass, so that the surface tension of the water droplet itself will produce a drop-like phenomenon. The water droplets will naturally slip away and take away the dust, so that the glass has an easy-cleaning effect. The dust will not be able to accumulate. Compared with the water staining of ordinary glass, there is a considerable difference in the long-term effect.

Basic Features

The phenomena of the two basic physical characteristics are reversed, namely:

a, hydrophobic (also known as "hydrophobe", English: Hydrophobe): refers to a substance (molecular) has a strong repulsion of water. Water on the surface of a hydrophobic object will form a large contact angle It is made into a drop of water. Our common lotus leaf has this effect.

b. Hydrophile: refers to the ability of a hydrophilic molecule to form a transient bond through a hydrogen bond and a water molecule, making water particularly easy to bind to a hydrophilic surface. Our common capillary phenomenon is this principle.

"Easy-clean coatings" for glass and ceramic surfaces, or "self-cleaning coatings" can be broadly classified into three categories:

The first type: the main component is silicone (or silicone organic resin) or other oily material composition, the surface of the material gives a smooth feeling, but it does not interact with the silica molecules on the surface of the material to form a strong Nano-film, but just fills the surface of the uneven material that we can't see with the naked eye, so that the surface of the material is smooth and uniform. The advantage is that it has a strong repellency to water (but not to oil). The disadvantage is poor adhesion. In a short period of time (6-12 months), its water repellent properties will be greatly reduced.

The second category: the main component is titanium dioxide (TiO2). After plating/coating a layer of titanium dioxide film on the glass, titanium dioxide is super-hydrophilic due to its ability to produce good photocatalytic properties under the action of (ultraviolet) light energy. Utilizing this super-hydrophilic property (as opposed to the hydrophobic properties of gold seal paint), it allows small droplets of water to condense into large droplets that fall off under the influence of gravity, making stains contaminated on them easy. It is washed away by water, making the glass easy to clean, so it is especially suitable for outdoor architectural glass. The advantage is that the price is cheap, the disadvantage is that there must be ultraviolet radiation, and the adhesion is also not good.

The third category: the main component is inorganic nano-silicon material, the representative product is Japan Haoruijia self-cleaning coating, which is characterized by super-hydrophilic coating on the surface and good anti-dust, independent of sunlight, in the completely light-free environment. The role is an upgraded version of the titanium dioxide product.

Japanese chemists have invented a glass that is self-cleaning and does not fog. The surface of the glass has "double wettability" and can be stained with both water and oil. Therefore, when there is moisture on the glass, it will spread over the entire surface of the glass without forming condensation. . In addition, water can penetrate into the oily dirt in this mutual understanding and mutual exchange, and the oil can be washed away, so that it can have a strong self-purification ability. Some people have done such an experiment. When spraying water vapor into the glass, the ordinary glass is already covered with fog beads, and the glass can still be read by people through text and pictures.

Ordinary glass surface is easy to generate static electricity, it will absorb floating dust in the air, car exhaust, for a long time, it is very easy to be dirty, in addition, when it rains, the contact angle between glass and water is 30-40 degrees, so the glass surface is very It is easy to form water droplets, and the water droplets are not easy to slip. During the drying process of the water droplets, it is very easy to suck the dust in the air, and after drying, water marks are formed, and the dirt is formed for a long time.

Self-cleaning glass, also known as self-cleaning glass, is an eco-friendly “green glass”. It can be made into self-cleaning glass by coating a layer of transparent titanium dioxide and a photocatalyst film on the surface of the flat glass. When a titanium dioxide photocatalyst film called a photocatalyst is exposed to sunlight or a fluorescent lamp or ultraviolet light, organic matter and contaminants adhering to the surface become carbon dioxide and water and are automatically eliminated by excitation of external light.