Product No. GT-PVDF-3

Polyvinylidene fluoride (PVDF) is a fluorine-containing polymer material with a fluorine content of up to 59%. Its chemical structure is bonded by fluorine-carbon bonds (as shown in Figure 1). Such short bond structure forms a stable and strong bond with hydrogen ions, therefore, the fluorocarbon coating has excellent wear resistance and impact resistance, and it shows excellent resistance to fading and UV in extremely harsh environments.

Figure 1: Schematic diagram of the chemical structure of PVDF

In the current market, the most common PVDF coating products for building exterior walls are KYNAR 500 or HYLAR 5000 brand products. These exterior coatings of buildings all over the world have been tested for 30 years with proved maintenance of the original appearance, demonstrating the excellent durability, weather resistance, UV aging resistance and weatherability of fluorocarbon coatings. The PVDF coating is now widely used in the field of drinking water treatment filters, lithium batteries, solar back panels, etc. However, due to its crystallinity, PVDF film is not completely transparent (as shown in Fig. 2). Generally, the optical problem of fluorine-based polymer can be solved by the organic/organic mixing method, but the excellent weatherability will be affected correspondingly.

Figure 2: The figure on the left is the traditional pure PVDF film, which is opaque; the figure on the right is the size of its crystalline particles.

To solve this problem, our company has developed the GT-PVDF-3 transparent film, which is a special crystallization technology that does not introduce other hydrocarbon polymers. In addition to retaining the weather resistance of fluorine-based polymers, the technology can greatly improve optical properties and mechanical properties of the optical film with high transmittance, low haze and good weatherability. The GT-PVDF-3 transparent film is shown in Figure 3.

Figure 3: The figure on the left is the GT-PVDF-3 transparent film; the figure on the right is the size of its crystalline particles.

Table 1 shows the optical properties and mechanical strength of the traditional PVDF film and GT-PVDF-3 film. GT-PVDF-3 can achieve a transmittance of more than 92% at 550 nm wavelength, while the transmittance of the conventional PVDF film is only 74.16% at the same wavelength of 550 nm. After 12,000 hours of accelerated weather test of QUVA, the transmittance of GT-PVDF-3 at wavelength 550nm can reach more than 90%, and the color difference △b<1.0, △E<1.0.

Film thickness TT%@
b* Haze Yong’s
Tear Strength (gf) Elongation (%)
Traditional PVDF film 23㎛ 74.16 >5 0.95 73.5 50
GT-PVDF-3 film 30㎛ 92.16 <1 0.3~0.5 1223.4 67.3 44
Table 1: Optical properties and mechanical strength of conventional PVDF film and GT-PVDF-3 film

The GT-PVDF-3 high transparent weatherability film has passed PV related reliability verification tests, including:
1.Flame resistance
•Spread of flame test (IEC 61370-2)
•Burning brand
•Flying sparks test
•85°C 85RH 2,000hrs
•105°C 300hrs
•UV aging 2,000hrs