1. Principle
Carry out freezing and heating tests on the ink for a certain period of time, and observe whether the ink is gelled or reversed.
2. Tools and materials
(1) An iron box that can hold 20g of ink.
(2) Automatic control thermostat.
(3) Automatic control freezer.
(4) Fluidity tester.
(5) Adjust the ink knife.
(6) Transparent measuring scale (scale value is 1mm).
3. Inspection method
(1) Put the tested ink into two iron boxes, each box containing no less than 15g of ink. The ink in the iron box should exclude air bubbles, then seal the cellophane and mark, cover the iron box, and then put them separately Take it into a 75-80 ℃ automatic control thermostat and a -15 ～ -20 ℃ freezer for 72h, and store at room temperature.
(2) The test inks that have been stored at room temperature for more than 3 hours are tested for fluidity according to the "Ink Fluidity Test Method" and compared to the inks that have not been tested for heating and freezing.
(3) According to the difference in the fluidity of the tested ink and the performance change of the ink, determine whether the tested ink is stable according to the following regulations.
â‘ The fluidity after the test is less stable than that before the original test, which means the ink is stable.
â‘¡After the test, the fluidity becomes larger than before, and the ink quality is still good. The possibility of this ink becoming gelatinized is not high, but it is not stable enough.
â‘¢ After the test, the fluidity becomes smaller than before, and the ink properties become "short" and "stand up", which means that there is a tendency to gel. Generally, this type of ink is only easy to gel.
4. Matters needing attention
(1) The freezing test method mainly determines whether it is anti-coarse.
(2) Heating test, mainly to determine whether there is the possibility of gelatinization.
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