T/CSAE 72-2018Test and evaluation method for UV penetration resistance of automotive coatings (English PDF)

3.1 Solar ultraviolet radiation

Ultraviolet radiation ranges from 290 nm to 400 nm.

3.2 UV penetration

Electromagnetic radiation with an ultraviolet wavelength of 290 nm to 400 nm is measured using an ultraviolet-visible spectrophotometer with an integrating sphere attachment Transmittance in the range of 401 nm to 550 nm solar radiation.

3.3 Quartz Slides

Quartz slides are made of quartz glass and have good light transmission in the entire spectral range from ultraviolet to infrared.

Energy. The maximum light transmittance in the ultraviolet region can reach over 80%, and the light transmittance in the visible light region can reach over 93%. Test quartz glass the sheet thickness is required to be 1 mm to 3 mm.

2T/CSAE ××-2017

3.4 Integrating sphere

It is a hollow sphere, the inner surface is coated with a highly reflective diffuse reflection coating such as barium sulfate, with a photodetector, and the total opening area of the integrating sphere Does not exceed 10% of the internal surface area of the integrating sphere.

5.2 Oven. room temperature + 5 ° C ~ 300 ° C, accuracy ± 2 ° C

5.3 Magnetic Thickness Gauge. Accuracy 0.1 µm

5.4 Height difference film thickness gauge. accuracy 0.1 µm

5.5 UV-visible spectrophotometer

The UV-visible spectrophotometer is shown in Figure 2. It must meet the JJG 178 UV, visible, near-infrared spectrophotometer verification procedure II Level requirements, the instrument needs to have an integrating sphere.

Figure 1 Integrating sphere

sample

Detector

Integrating sphere Whiteboard 3T/CSAE ××-2017

6.1 Method A (peeling film forming method)

6.1.1 Coating film preparation

1) Coating preparation. sample preparation and dilution according to the conditions specified in the coating product specification, adjust the viscosity of the coating to the construction Viscosity, sampling with reference to GB/T 3186 paint, varnish and paint and varnish raw materials sampling;

2) Test plate preparation. paste the polypropylene plate or Tedlar polyvinyl fluoride film in the middle of the tinplate and the tinplate near one side Apply tape on the board (measuring film thickness);

Figure 2 UV-visible spectrophotometer

light source

Slit adjustment mechanism Monochromator spectroscopic system Sample compartment Detector

Figure 3 Schematic diagram of the peeling film forming method

tape

Film thickness calibration point Tinplate Polypropylene board Film peeling, coating film interception range 30 mm × 18 mm Choose a level that meets the requirements Line measurement film thickness, red circle Circle indicates film thickness detection point 4T/CSAE ××-2017

3) Prepare the paint film according to the general preparation method of GB/T 1727 paint film. Polypropylene plate or Tedlar polyfluoride to be attached to the tinplate the vinyl film is automatically sprayed by hand or automatically sprayed with the robot with the parameters to be measured, and the film thickness is measured from top to bottom.

Increase the principle to obtain a coating film with different film thicknesses. If the water-based paint is pre-baked (usually 80 ° C/10 min), then try again the plate is placed in an oven and baked according to the drying window of the paint (generally 140 ° C/30 min), and then cooled for use. If a composite coating is prepared the test film of the film is flashed or dried according to the specified process conditions, and then the next coating is sprayed, and finally completely dried for use. Such as If the spray coating thickness exceeds the normal construction range, adjust the drying temperature and drying time;

6.1.2 Determination of film thickness

1) Preliminary measurement of the film thickness of the coating film. after removing the tape paper on the tinplate, and calibrating the film thickness gauge with the exposed tinplate as the substrate, the film thickness of the coating film on the tinplate was measured as the coating film thickness on the polypropylene plate or the Tedlar polyvinyl fluoride film on the corresponding horizontal line. Horses mouth the difference in film thickness between the two sides of the iron plate should be strictly controlled. The film thickness should be within 15 µm (including 15 µm).

Within 1 µm; if the film thickness is above 15 µm, the difference in film thickness between the two sides should be controlled within 2 µm, then it is considered as a qualified film available.

UV transmittance detection;

2) Peeling of the coating film. the coating film on the polypropylene sheet or the Tedlar polyvinyl fluoride film is cut with a knife, and the coating film is small in the horizontal direction.

The heart is peeled off from the polypropylene sheet or the Tedlar polyvinyl fluoride film to prevent the film from being stretched;

3) Confirmation of coating film thickness. Align the film thickness gauge with the tinplate as the substrate again, and place the peeled film test specimen flat on the horse.

On the mouth plate, covered with a transparent plastic film for film thickness measurement, the measurement method according to GB/T 13452.2 paint and varnish film thickness measurement Line measurement. The same film test piece was measured in parallel for three times, and the film thickness difference was within 1 µm, and the ultraviolet transmittance detection data was effective.

6.1.3 Penetration detection

1) The film test piece needs to be adjusted before the test. Unless otherwise specified, it is generally required to refer to the temperature specified in GB/T/9278.

Adjust at (23 ± 2) ° C and relative humidity (50 ± 5)% for at least 16 h.

2) The UV-Vis spectrophotometer needs to be preheated for 30 min before testing.

3) Device parameter setting suggestion. measurement wavelength range is 290 nm to 550 nm, data acquisition interval is 1 nm, slit width not more than 2 nm, the time is not less than 0.5 s;

4) Place the highly reflective whiteboard on the reflection port of the integrating sphere. Place the substrate on the transmission port of the integrating sphere, scan the baseline, and measure the blank.

After the baseline is completed, the substrate is replaced with the sample to be tested, the penetration curve of the sample is scanned, and the same film is tested for 3 rounds to observe the weight.

Present.

5) The test film is tested and the data is saved. The penetration rate data is retained three decimal places. Remove the coated test piece and turn off the instrument.

6.1.4 Data Analysis

1) Input the evaluation criteria of the determined UV-resistant transmittance into the computer to form a standard curve, and test the test film.

The light transmittance curve is compared and analyzed with a standard curve to determine the ultraviolet penetration resistance level of the coated film.

2) The film thickness of the tested test film was analyzed using the data determined in 6.1.2.

6.2 Method B (quartz slide film formation method)

6.2.1 Coating film preparation

1) Coating preparation. sample preparation and dilution according to the conditions specified in the coating product specification, adjust the viscosity of the coating to the construction 5T/CSAE ××-2017 Viscosity

2) Test plate preparation. Paste the quartz glass slide in the middle of the tinplate and apply glue on the tinplate near the side of the slide.

With paper (for measuring film thickness).

3) Prepare the paint film according to the general preparation method of GB/T 1727 paint film. Automatically spray by hand or automatically set up the parameters of the robot Spray the coating to be measured, and increase the film thickness from top to bottom to obtain a coating film with different film thicknesses. If it is a water-based paint, it is pre-After drying (generally 80 ° C/10 min), the test plate is placed in an oven and baked according to the drying window of the paint (generally 140 ° C/30 min).

After cooling, it is ready for use. If a coated test piece of a composite coating is prepared, it may be flashed or dried according to the specified process conditions before the next coating is applied.

Sprayed and finally completely dried for use. If the spray gradient film thickness exceeds the normal construction range, adjust the drying temperature and drying time;

6.2.2 Determination of film thickness

Preliminary measurement of film thickness. remove the tape paper on the tinplate, and calibrate the film thickness gauge with the exposed tinplate as the substrate.

The film thickness of the coating film was measured on the tinplate as the thickness of the coating film on the quartz glass slide. The film thickness difference between the two sides of the tinplate should be strict Control, film thickness within 15 µm (including 15 µm), the difference in film thickness between the two sides should be controlled within 1 µm, the film thickness is 15 µm on the upper side, the difference in film thickness between the two sides should be controlled within 2 µm, which is regarded as a qualified film and can be used for UV transmittance detection.

6.2.3 Permeability detection

The penetration rate detection process is tested in accordance with 6.1.3.

6.2.4 Re-confirmation of film thickness

The coating film on the transmittance test area of the quartz glass slide is partially destroyed to expose the slide substrate, and the stone is determined by the height difference method.

The thickness of the coating on the UK slide, the film thickness of the same slide penetration test area was measured in parallel three times, and the film thickness difference was 1 µm.

Within this, the UV transmittance detection data is valid.

6.2.5 Data Analysis

1) Input the determined UV-resistant transmittance evaluation standard into the computer to form a standard curve, which will be tested on the test film.

Figure 4 Schematic diagram of quartz glass film forming method

Select a horizontal line that meets the requirements to measure film thickness Red circle indicates film thickness detection point Tinplate tape Film thickness calibration point Quartz slide 6T/CSAE ××-2017 the light transmittance curve was compared and analyzed with a standard curve to determine the ultraviolet penetration resistance level of the coated film.

2) The film thickness of the test film test piece was analyzed using the data measured in 6.2.4.