Deterioration of color coated board

The organic coating on the surface of the color coated plate has the function of covering and protection, which can effectively prevent the corrosion of the substrate under the coating. The coated plate selected by the color coated plate also has corresponding corrosion resistance. Therefore, the corrosion process of color coated plate mainly includes coating deterioration and substrate corrosion. The first is the deterioration and falling off of paint film, and then the corrosion of substrate.

In the general environment, the degradation process of color coated board first shows the reduction of gloss, then causes discoloration and pulverization from the surface, and finally the coating falls off due to the degradation and decomposition of resin. The galvanized steel plate will lose its protective coating and then corrode.

Deterioration process

Loss of gloss -- > discoloration -- > cracking of powdered surface -- > blistering and falling off of coating -- > White / red rust

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Experimental contents and results

Acid and alkali resistance test

principle

Immerse the sample in a certain concentration of acid / alkali solution for a certain time, and then take it out to evaluate the change of color difference and gloss, as well as whether there are discoloration, blistering, falling off and other phenomena of the coating.

result

According to GB / T 1766, the samples shall be evaluated for the loss of light grade, discoloration grade, foaming grade and falling off grade. The test results of parallel samples shall take the worst value as the test results.

Test results of acid and alkali resistance of fipt color coated plate

Test conditions: 5% hydrochloric acid, 5% sodium hydroxide, soaking at room temperature for 24 hours.

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Test standard: GB / T 13448-2006 test method for color coated steel plate and strip

Evaluation standard: GB / T 1766-2008 aging rating method for paints and varnishes

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Neutral salt spray resistance test

principle

After the sample is exposed to neutral sodium chloride spray for a specified time, evaluate its surface blistering, corrosion grade and corrosion propagation distance.

result

1. For flat samples, evaluate the foaming grade and rust grade according to GB / T 1766, and take the worst value of parallel samples as the experimental result

2. For the cross and notch samples, select a representative area on the scribed line, measure the maximum corrosion spread distance from the scribed line to blistering and corrosion at at at least 6 equal distance positions, and take its arithmetic average, that is, the average corrosion spread distance. Record the maximum and minimum corrosion spread distance of the scribed line

Results of neutral salt spray test of fipt color coated plate

Test conditions: 5% NaCl, 35 ± 2 ℃ continuous spraying

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Test standard: ASTM b117-2003 standard method for salt spray test

Evaluation standard: GB / T 1766-2008 aging rating method for color paints and cleaning coatings

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Accelerated aging test of ultraviolet lamp

principle

The test is exposed to ultraviolet light and / or condensation atmosphere. After the specified test cycle, measure its gloss and color difference, and evaluate its discoloration, loss of light, pulverization and other coating surface aging phenomena.

result

Evaluate the discoloration grade and light loss grade of the sample according to GB / T 1766, and take the worst value of the parallel sample as the experimental result.

Accelerated aging test results of feipute color coated plate UV lamp

Test conditions: UVA-340 light source, 0.77w / (m2. Nm)

8 hours ultraviolet light, blackboard temperature 60 ± 3 ℃; Condensation for 4 hours, blackboard temperature 50 ± 3 ℃

UV lamp results png

Test standard: GB / T 13448-2006 test method for color coated steel plate and strip

Evaluation standard: GB / T 1766-2008 aging rating method for paints and varnishes

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Damp heat resistance test

principle

Using the non condensing damp heat method, place the test sample in a closed test chamber with a temperature of 50 ± 2 ℃ and a relative humidity of no less than 98%. Use the very slight temperature difference between the sample and the surrounding steam to form condensate on the sample, and evaluate the water penetration resistance of the sample coating.

result

Evaluate the grade of blistering, cracking and corrosion of the sample according to GB / T 1766, and take the worst value of the parallel sample as the test result.

Test results of heat and moisture resistance of fipt color coating

Test conditions: the temperature is 50 ± 2 ℃, and the relative humidity is ≥ 98%.

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Test standard: GB / T 13448-2006 test method for color coated steel plate and strip

Evaluation standard: GB / T 1766-2008 aging rating method for color paints and cleaning coatings

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