Tests for wettability and adhesion In industrial practice, the determination of the surface energy of a polymer is performed by testing the ink in accordance with DIN ISO 8296 or ASTM D 2578-99a.
According to the DIN ISO 8296 method, an ink about 100 mm long is brushed on the film to be measured with an ink having a different surface energy, and whether more than 90% of the ink strips contract and form within 2 seconds is observed. The ink droplets, if any, are replaced by ink of a lower surface energy level and the ink strips are brushed again to perform the same observation until no shrinkage or ink droplets occurs. The surface energy of the test ink corresponds to the surface energy of the film. This method is a method for testing the intermediate value of the surface energy, which is small and does not count.
In accordance with ASTM D 2578-99a, a block of approximately 25 x 25 mm is applied using a cotton padding test ink, and the minimum surface energy value of the film is measured by the same method as described above. This test method is difficult to grasp due to the thickness uniformity of the ink layer, its accuracy is less than DIN ISO 8296 method, the error of DIN ISO 8296 is approximately within ±1mN/m, and the error of ASTM D 2578-99a is approximately ±2 mN/ m. Therefore, in the industrial practice, the DIN ISO 8296 method is mostly used, and it is simpler and faster. (In China, there is a national standard GB10003-88 for the corona treatment effect test method provisions, for reference.
Regardless of the method used, the same Softal test ink can be used, with test inks of 30 to 72 mN/m of twenty-one surface levels (each differing by 2 mN/m). Dyne test pen (38mN/m) can be used as a rapid test tool for surface energy after corona treatment, but it is not suitable as a system test for printed or coated surfaces. When the test pen draws a line on the corona-treated surface, if it is continuously lined, it means that the surface energy of the material is not less than 38mN/m, such as intermittently not connected, indicating that the surface energy of the material is less than 38mN/ m. Insufficient or even untreated, not meeting the printing process requirements.
If the plastic film contains a large amount of additives or is coated with a coating film, chemical reactions tend to occur when testing with the above test ink or test liquid, which affects accuracy. In this case, distilled water is recommended for contact angle testing.
Rapid determination of the adhesion of paints, coatings, inks, etc., can be used for tape adhesion testing according to ASTM D 3359-97.
Third, corona treatment Corona processor consists of electrodes, high potentiometer and roll guide roller, when the voltage exceeds the ionization resistance of the air gap of 1-2mm, it will produce continuous discharge, due to the dielectric on the guide roller discharge Get a uniform dispersion. The electrodes are housed in a hood to prevent contact. In order to reduce the temperature and remove the generated ozone, an exhaust fan was used to blow out the air near the corona processor. However, in order to prevent the ozone from being emitted, the exhaust must first pass through an air purifier.
Corona treatment increases substrate adhesion by the following mechanisms:
• Removal of absorbed atoms and molecules on the surface.
Promotes atomic contact and enhances wetting.
• Improve surface energy and adjust polarity.
· Create atoms or functional groups that can react chemically.
The physical and chemical effects of corona treatment on plastic surfaces are complex, and their effectiveness is mainly controlled in three ways:
1, a specific electrode system;
2. The dielectric on the guide roller;
3, the specific electrode power.
As for the speed of winding, the width of the roll, and the variety of plastics, only the motor power is adjusted, and some are automatically controlled, and the repeatability of the effect is guaranteed. (To be continued)
According to the DIN ISO 8296 method, an ink about 100 mm long is brushed on the film to be measured with an ink having a different surface energy, and whether more than 90% of the ink strips contract and form within 2 seconds is observed. The ink droplets, if any, are replaced by ink of a lower surface energy level and the ink strips are brushed again to perform the same observation until no shrinkage or ink droplets occurs. The surface energy of the test ink corresponds to the surface energy of the film. This method is a method for testing the intermediate value of the surface energy, which is small and does not count.
In accordance with ASTM D 2578-99a, a block of approximately 25 x 25 mm is applied using a cotton padding test ink, and the minimum surface energy value of the film is measured by the same method as described above. This test method is difficult to grasp due to the thickness uniformity of the ink layer, its accuracy is less than DIN ISO 8296 method, the error of DIN ISO 8296 is approximately within ±1mN/m, and the error of ASTM D 2578-99a is approximately ±2 mN/ m. Therefore, in the industrial practice, the DIN ISO 8296 method is mostly used, and it is simpler and faster. (In China, there is a national standard GB10003-88 for the corona treatment effect test method provisions, for reference.
Regardless of the method used, the same Softal test ink can be used, with test inks of 30 to 72 mN/m of twenty-one surface levels (each differing by 2 mN/m). Dyne test pen (38mN/m) can be used as a rapid test tool for surface energy after corona treatment, but it is not suitable as a system test for printed or coated surfaces. When the test pen draws a line on the corona-treated surface, if it is continuously lined, it means that the surface energy of the material is not less than 38mN/m, such as intermittently not connected, indicating that the surface energy of the material is less than 38mN/ m. Insufficient or even untreated, not meeting the printing process requirements.
If the plastic film contains a large amount of additives or is coated with a coating film, chemical reactions tend to occur when testing with the above test ink or test liquid, which affects accuracy. In this case, distilled water is recommended for contact angle testing.
Rapid determination of the adhesion of paints, coatings, inks, etc., can be used for tape adhesion testing according to ASTM D 3359-97.
Third, corona treatment Corona processor consists of electrodes, high potentiometer and roll guide roller, when the voltage exceeds the ionization resistance of the air gap of 1-2mm, it will produce continuous discharge, due to the dielectric on the guide roller discharge Get a uniform dispersion. The electrodes are housed in a hood to prevent contact. In order to reduce the temperature and remove the generated ozone, an exhaust fan was used to blow out the air near the corona processor. However, in order to prevent the ozone from being emitted, the exhaust must first pass through an air purifier.
Corona treatment increases substrate adhesion by the following mechanisms:
• Removal of absorbed atoms and molecules on the surface.
Promotes atomic contact and enhances wetting.
• Improve surface energy and adjust polarity.
· Create atoms or functional groups that can react chemically.
The physical and chemical effects of corona treatment on plastic surfaces are complex, and their effectiveness is mainly controlled in three ways:
1, a specific electrode system;
2. The dielectric on the guide roller;
3, the specific electrode power.
As for the speed of winding, the width of the roll, and the variety of plastics, only the motor power is adjusted, and some are automatically controlled, and the repeatability of the effect is guaranteed. (To be continued)
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