The fluorocarbon coating itself determines that the spraying equipment must have a good atomization effect to ensure the uniformity of the spraying layer. The distribution of metal particles in fluorocarbon coatings directly influences the appearance of the coating. The fluorocarbon coating with uniform coating and fine quality has metallic luster and bright color, which has a clear three-dimensional feeling. The fluorocarbon coating, which is not suitable for spraying, is uneven in color, with a shadow or a coating on the surface. In order to get good spray effect, high voltage electrostatic spraying gun should be used.

Aluminum veneer fluorocarbon spraying process with multi-layer spray, from aluminum veneer of pretreatment to the spraying process are to strictly control the quality, the final product must meet the requirements of the American association of building manufacturing AAMA - 605.02.90 standard. The aluminum - plastic composite board generally adopts multi-layer rolling process.

The process of fluorocarbon spraying on aluminum veneer is as follows:

Aluminum veneer pretreatment: surface oil to the sewage wash, alkaline wash (defatting), water - wash - Spray, spray primer - flow flat - spray paint to flow flat, spray the paint coat - flow flat - curing (180 ~ 250 ℃) to quality inspection, packaging.

The multi-layer spraying process can be divided into three spraying (three spray, primer, finish and finish paint). Secondary spray (primer, finish).

1. Pretreatment process

Pretreatment is to make the aluminum alloy plate before spraying through to oil decontamination and chemical processing, to produce chromium film, increase the adhesion strength of the coating and the metal surface and anti-oxidation ability, is helpful to extend the lifespan of the paint film.

The chromium treatment method consists of two steps: 1. The formation of chromate film sintering.

When using chemical degreasing, should be careful not to use caustic degreasing agent. It can be treated with a hot alkali solution or spray degreasing. Alkali solution temperature is 600 ℃, the concentration of 50 g/L, time is 3 ~ 5 min.

Composition of chromate liquid: chromium sulfate 2g/kg tank solution; Potassium dichromate 147g/kg tank solution; Sodium hydroxide 79g/kg tank solution; Water 772g/kg tank solution.

After the pretreatment, the operator should wear cotton glove operation.

2. Spraying technology

Primer painting: the role of the primer coating is to improve the penetration resistance of the coating, strengthen the protection of substrate aluminum plate, stable aluminum veneer surface layer, strengthen paint and adhesion on the surface of the aluminum plate, ensure that the color of the paint coating uniformity. The base coat thickness is generally 5~ 10um.

Spray paint, paint coating is to provide aluminum veneer decoration colors, needed to protect the surface of aluminum plate from the external environment, acid rain, atmospheric pollutants, prevent ultraviolet penetration, enhance the capacity of anti-aging. The thickness of the surface coat is 23~ 30um. Before spraying paint layer, primer coating shall be dry, and spraying the workpiece temperature does not exceed 50 ℃. If spraying on too hot workpiece can make the coating surface rough.

Cover the paint spraying coat: light is also called the varnish coating, paint coating main purpose is to more effectively enhance paint layer of the erosion resistance, protect the paint coating, increase the luster of the paint color, more colorful, brilliant appearance, coating thickness is usually 5 ~ 10 um. The total thickness of the three spray coating is 40~60um, and the special needs can be thickened.

3. Curing process

The three coating layers generally need to be solidified twice. Coated aluminum veneer into curing furnace, curing temperature generally between 180 ~ 180 ℃, the curing time is 15 ~ 25 min. Different fluorocarbon coating manufacturers will provide the best curing temperature and time according to their own paint. You can also change the secondary solidification of the three spray according to your own experience.