GB/T 13217.4-2020Test method for viscosity of ink (English PDF)

4.3 Tools and materials

4.3.1 Zahn cup viscometer: It is in accordance with ASTM D4212; the measurement range shall be less than 80 s.

4.3.2 Thermometer: The temperature range is 0 °C ~ 50 °C; the graduation value is 0.1 °C.

4.3.3 Scrubbing solvent: Different system liquid inks use the same series of special solvents.

4.4 Testing conditions The testing shall be carried out under constant ambient temperature (23 ± 2) °C.

4.5 Testing steps

4.5.1 Select a representative specimen to be tested according to the provisions of GB/T 3186; wipe the inner wall of the viscosity cup and the leaking nozzle clean; hold the viscosity cup horizontally; use finger to block the leaking nozzle; pour the specimen which was stir evenly and adjusted to the temperature of (25 ± 0.2) °C into the viscosity cup, until it is flush with the edge of the viscosity cup; use glass rod to scrape off the air bubbles; reset the stopwatch to zero.

4.5.2 Release the finger and turn on the stopwatch at the same time. When the specimen flow is interrupted and the first drop appears, stop timekeeping. At this time, the time indicated by the stopwatch is the viscosity of the ink specimen.

4.6 Test results The test shall be carried out twice in parallel; the difference between the measured value and the average of the two measurements shall be less than 5%, the average of the two test results is the viscosity of the ink specimen. During the test, select the appropriate Zahn cup number, to facilitate the shortened to 10 minutes), record the data when the reading on the instrument is stable. Test again and record the data.

5.1.6 Test results Check the two test results; the difference between the measured value and the average of the two measurements shall be less than 5%, then the average of the two test results is the viscosity of the ink specimen. During the test, select the appropriate rotor or speed to accurately test the viscosity of the ink specimen.

5.2 Cone-plate viscometer method

5.2.1 Principle Cone-plate viscometer is a kind of rotary viscometer. The tested specimen is between the two plates; the cone-plate is driven to rotate due to the intermolecular friction. The greater the friction, the greater the viscosity of the specimen. The unit is expressed in cP (1 cP = 10-

5.2.2 Scope of application It is suitable for testing pasty inks.

5.2.3 Tools and materials

5.2.3.1 Cone-plate viscometer: It is in accordance with GB/T 9751.1; the measuring range is

0.001 Pa·s ~ 200 Pa·s.

5.2.3.2 Thermometer: The temperature range is 0 °C ~ 50 °C; the graduation value is 0.1 °C.

5.2.3.3 Scrubbing solvent: Liquid inks of different systems use the same special solvents.

5.2.4 Testing conditions The testing shall be carried out under constant ambient temperature (23 ± 2) °C.

5.2.5 Testing procedure

5.2.5.1 Check whether the instrument is clean before measurement; turn on the power switch; perform preheating and calibration.

5.2.5.2 Set the instrument at constant temperature (25 ± 0.2) °C; set the preheating and test time; select a suitable rotor.

5.2.5.3 Select a representative specimen to be tested according to the

6.5.1 Select a representative specimen to be tested according to the provisions of GB/T 3186; use an ink mixer to mix about 5 g of the specimen thoroughly; adjust it to the test temperature of (25 ± 0.2) °C; the specimen shall be uniform and without any rough particles. The selection of the load weight shall refer to the viscosity of the specimen; the maximum load weight shall generally be such that the fall time is within the range of 4 s ~ 10 s. The amount of the specimen shall be enough to fill the gap between the falling stick and the pores of the ring; meanwhile it shall be smeared on the lower part of the stick. Before starting the test, rotate the falling stick to distribute the specimen evenly. Use the maximum load to carry out a test. At this time, the falling stick and the periphery of pores are all wetted by the specimen.

6.5.2 Insert the falling stick into the hole of the ring to the support piece and make it stand still. Select a series of load weights for testing, the longest falling time is not more than 60 s; after each operation, use an ink mixer to scrap off the specimen on the falling stick; recoat it on the lower part of the stick. No other liquid shall be added during the test. The temperature of the specimen shall be checked before and after the test.

6.5.3 In accordance with the operation steps of 6.5.2, repeat the test three times; then record the data.

6.5.4 After the test is completed, the instrument shall be cleaned immediately by the use of a lint-free cloth and a suitable solvent.

6.6 Calculation method

6.6.1 Shear stress Shear stress is the force acting on a unit area and parallel to the acting surface; the unit is Pa. For the falling stick viscometer, the shear stress is proportional to the total amount of the stick and the applied load, which is calculated according to formula (1): Where: sigma - Shear stress, in Pascal (Pa); W - The total weight of the stick and the applied load, in Newton (N); A - Apparent shearing area, in square meters (m2); L - The falling distance of the falling stick (the distance between the start point and the end point of the timekeeping), in meters (m).

6.7 Test results Calculate the ink specimen's viscosity according to formula (5); the relative deviation of the three test results shall be less than 20%, then the average of the three test results is the ink specimen's viscosity.

7.3 Tools and materials

7.3.1 Parallel plate viscometer: It is in accordance with GB/T 14624.3; the measuring range is

0.001 Pa·s ~ 200 Pa·s.

7.3.2 Thermometer: The temperature range is 0 °C ~ 50 °C; the graduation value is 0.1 °C.

7.3.3 Scrubbing solvent: Different system liquid inks use the same series of special solvents.

7.4 Testing conditions The testing shall be carried out under constant temperature (23 ± 2) °C.

7.5 Testing procedure

7.5.1 Before testing, check whether the instrument is clean; level it so that the instrument is in the leveling state.