Analysis of Low-E Glass Coating Principle and Technology Classification

2025-05-13 09:12:05

1、Coating principle

Low-E glass achieves low radiation characteristics by coating multiple layers of metal or compound films (such as silver and tin oxide) on the surface of the glass, with the core being the high reflectivity of the silver layer towards mid to far infrared radiation (reflectivity>98%). The emissivity of the silver layer can be reduced to 0.02-0.12, much lower than the 0.84 of ordinary glass. It reduces energy exchange by reflecting thermal radiation while maintaining a visible light transmittance of over 80%.

2、Comparison of Technical Categories

Online coating technology

Directly spraying tin oxide and other materials on the high-temperature section (about 600 ℃) of the float glass production line, the film layer is firmly bonded to the glass substrate and can be used as a single piece, but the radiation rate is high (0.17-0.22) and the thermal insulation performance is limited.

Offline coating technology

Using vacuum magnetron sputtering technology, a composite film system is coated with a silver layer and a dielectric layer (such as TiO ₂, Si ∝ N ₄), with a radiation rate as low as 0.01 or below and better thermal insulation performance, but it needs to be processed into a protective film layer for insulating glass.

3、Functional layer evolution

Single silver Low-E: containing 1 layer of silver and 4 layers of medium (a total of 5 layers), with a shading coefficient of 0.3-0.5;

Double silver Low-E: containing 2 layers of silver and 7 layers of medium (a total of 9 layers), the heat transfer coefficient is reduced by 0.1W/(m ² · K) compared to single silver, and the shading coefficient is reduced to 0.2-0.3;

Triple Silver Low-E: Contains 3 layers of silver and 10 layers of dielectric (a total of 13 layers), with an infrared barrier rate greater than 95%, suitable for ultra-low energy buildings.

4、Process adaptability

Online coating products have strong weather resistance and can be directly tempered, suitable for single panel use in curtain walls; Offline coating requires the use of a hollow layer (with the membrane surface facing inward) and further reduction of heat transfer coefficient to below 1.0 W/(m ² · K) through argon gas filling.

Low-E glass

Type: Soft coat, hard Coat

Thickness: 4mm, 5mm, 6mm.

Size: 1830x2440mm,2140×3300/3660mm etc.

Color: Clear, blue, green.

More product details:https://www.longboglass.com/product/9.html