Steps to Produce PVDF Coating On Aluminium
PVDF coating (a fluoropolymer product containing 70% polyvinylidene fluoride resins) has excellent resistance to fading, anti-blooming, anti-air pollution (acid rain, etc.), strong UV resistance, strong crack resistance and ability to withstand harsh weather conditions. Therefore, PVDF coated aluminum and aluminum sheets are mainly used in windows, curtain walls, and buildings in offshore areas.
FONNOV ALUMINIUM introduced the PVDF coating spray production line into its new extrusion plant, providing customers high quality PVDF coated aluminum profiles for architectural usage. The famous brands of fluoropolymer coating as well as strict production process enable its PVDF coating aluminium profiles to meet the AAMA2605 standard and GB/T5237.5 standard. Below is the introduction of PVDF coating process on aluminum.
The PVDF coating process uses multi-layer spray to give high performance to the durability and weather resistance. From the surface treatment of aluminum to the spray process, the production flow and quality test must be strictly controlled, so that the final product can reach the requirement of AAMA-2605 standard, and GB/T 5237.5 standard. The multi-layer spraying process has 3 types of coat system: 2-COAT system, 3-COAT system, and 4-COAT system. The most common ones are three sprays (referred to as 3 COAT) and two sprays (referred to as 2 COAT). The following describes the process. you also can learn about it from this video：PVDF (Fluoropolymer) Coating in FONNOV ALUMINIUM Plant CHINA.
Before coating the aluminum, the surface of the aluminium piece should be degreased and chemically treated to creat a chrome film, which help to increase the adhesion and oxidation resistance of the coating and the aluminum surface.
1 COAT – PRIMER COATING
A primer coating can improve the coating’s resistance to penetration, enhance the protection of the substrate, stabilize the metal surface layer, and enhance the adhesion of the top coat to the aluminum surface. The thickness of primer coating is generally 5-10 microns.
2 COAT – COLOR TOP COATING
The color top coating is the key layer of the spray coating. It provides the decorative color required for the aluminum to meet the design requirements and protect the metal surface from the external environment, acid rain and pollution. To prevent UV rays from penetrating. It greatly enhances the anti-aging ability. The top coating is the thickest layer of paint in the spray. The thickness of the color top coating is generally 25-30 microns.
3 COAT – CLEAR TOP COATING
The main purpose of the clear top coating is to more effectively enhance the lacquer coating’s resistance to external erosive, protect the color coating, increase the metallic luster of the coat color, and make the appearance more vivid and brilliant. The coating thickness is generally 10-15 microns.
The total thickness of the three coatings is generally 40-60 microns, which can be thickened for special needs.
3 Coat process generally requires two times curing. The curing temperature in the oven is generally between 230°C and 250 °C, and the curing time is generally 10-15 minutes. Different PVDF coating manufacturers will have their own instruction on curing temperature and time. Some coating plant adapts one time curing according to their own experience.
For 2 COAT process, there’s a little difference from 3 COAT process. 2 COAT process is followed by a color top coating after primer coating. The thickness of primer coating is generally 5-10 microns, and the thickness of colour top coating is 25-30 microns. 2 COAT process only require one time curing, the curing temperature is between 230 °C and 240 °C, and the curing time is generally 10-20 minutes.
PVDF Coating manufacturers generally can guarantee a coating life of 20 years or even 30 years. Also , FONNOV ALUMINIUM should emphasize that high-quality paint materials, proper production process, strict quality controlling, as well as regular effective maintenance on PVDF coated aluminum final product are all essential factors for long-term weatherability.