1. Thickness of aluminized film
The thickness measurement of aluminized film generally uses the following three methods.
The first is the optical density method, which is measured by the density of light passing through the aluminized film. The advantages of measuring the thickness of aluminized layer by optical density are convenience and accuracy, and the measurement result is not easily affected by the surface oxide layer. The optical density value is related to the wavelength of the incident light.
The second is to use surface sheet resistance measurement. This method is simple and practical. Generally, the surface resistance corresponding to the thickness of the aluminum layer is generally 1~2. Sampling or 1cm wide and long, the resistance value of 10cm is between 1-20. When the coating is just unrolled, the surface of the aluminum layer is less oxidized and the measurement is more accurate.
The third method is the visual estimation method. If two layers of aluminized film are stacked together to look at a fluorescent lamp or to the sky, the thickness of the coating should be more than 400 Å based on the invisible light. However, this method is easily affected by eye vision. When you put it in front of your eyes, the pupils of your eyes will adjust as the light becomes darker, and light that is not visible will be visible after the pupils are adjusted.
2. The uniformity of aluminized film coating
Take 8 to 10 samples with a specification of 100mm×100mm at equal distances along the transverse direction of the tested sample, measure the resistance value of the square with a resistance measuring instrument, and take the arithmetic average value, which is the coating resistance of the sample. The upper and lower deviations of the resistance value can be calculated. The deviation of the resistance layer resistance actually reflects the uniformity of the aluminum coating.
3. Fastness to aluminum plating
The fastness of aluminum plating is generally tested with tape. When qualitatively determining the fastness of the aluminum-plated layer with the adhesive tape, stick an adhesive tape about 15 cm long on the aluminum-plated surface and flatten it with your fingers. Then press the sample with one hand and peel off the adhesive tape at a constant speed with the other hand. Use a light box with strong light to test the transfer of the aluminum layer.
Another method to determine the fastness of aluminized layer is for PET aluminized film. A specially prepared test film and PET aluminized film are heat-sealed under certain heat-sealing conditions, and then the samples are cut and peeled off with a tensile testing machine to measure the peeling force and check the aluminum layer transfer in the heat-sealed area.
4. Physical and mechanical performance indicators
The physical and mechanical performance indexes of common aluminized films are shown in the following table: