About the knowledge of the color-coated board, one article will make you an expert! (part 3)

Coat reflectivity reflection effect

For coated steel sheets, the thermal expansion coefficients of coatings and steel sheets are usually different,

especially the decomposition of linear expansion coefficients of metal substrates and organic color coatings.

When the ambient temperature changes,

expansion or contraction stress will occur at the interface between the substrate and the coating,

and coating cracks will occur if it cannot be properly released.

Baosteel has done the same paint variety, the same paint supplier,

and the 8-year exposure test of different colors in Hainan,

and the results also confirmed that the light paint has little discoloration.

Can be compared for different color exposure tests

Gloss color difference, original thickness, current thickness

In addition, here I want to explain two misunderstandings in the current domestic market:

One is that a large number of white primers currently exist in China.

The purpose of using a white primer is to reduce the thickness of the topcoat,

because the normal corrosion-resistant primer for construction is yellow-green

(hence the strontium chromate pigment), and there must be enough topcoat thickness to have good hiding power.

In this way, it is very dangerous for corrosion resistance.

First, the primer has poor corrosion resistance, and the topcoat is greatly thinned to less than 10 microns.

This kind of color-coated steel sheet looks glamorous,

and corrosion will occur in different places in less than two years (vertical, bending, under the film, etc.).

The second is that the color-coated steel plate used in construction projects uses different manufacturers for the same project.

Different color-coated steel plates appear to have the same during construction,

but after several years of sunlight, the coat of different coatings and different manufacturers changes Different trends.

Even if it leads to products from the same supplier, it is strongly recommended that the same project be issued at once.

Because different batch numbers may use products from different coating suppliers,

increasing the possibility of color difference.

Reasonable selection of materials will not increase the volume of the building and reduce the cost,

so that it is truly environmentally friendly and resource-saving.