Determination of the viscosity of inks and adhesives using a rotary viscometer

Viscosity is a basic parameter for evaluating inks and binders. It can describe the properties of the ink on the press. The factors that affect tack value include: elastic roller diameter, hardness in terms of modulus, line pressure, roller properties, roller speed, roller temperature, ambient temperature and humidity, sample temperature, ink film thickness, ink or binder The effect on the elastic roller, the condition of the elastic roller in the cleaning process, the nature of the tested sample, and the like. This standard is just a guide, it does not replace the technical manual.

1 Scope of application

This standard specifies the general method for determining the viscosity of inks and adhesives.
This standard applies to the determination of the viscosity of inks that have low volatility and do not react during the test under normal environmental conditions.

2 Definitions

2.1 tack: The force of film separation between the two rolls of a given width, the ink or the binder on the roll surface.
Viscosity is a rheological parameter that represents the fluid's internal adhesive properties and other physical/chemical properties.

3 test methods

3.1 Principle

The rotary viscometer consists of three main components, one of which is a metal roller, the middle of which is empty and can be fed with circulating water to regulate the temperature. This roller is a motor-driven active roller, the speed can be adjusted; the other roller is synthetic The rubber roller is pressed on the metal roller by its own weight, and is connected with the lever showing the balance state; the third roller is a roller used for coating the sample to be tested. The viscosity measured by the separation of the film layer of the ink or the connecting material was measured with a tack meter and expressed numerically as the tack value.
3.2 Instruments and Materials 3.2.1 Rotary Viscometer 3.2.2 Injector: Accuracy ±1%
3.2.3 Stopwatch or Timer: Accuracy ±0.2 seconds 3.2.4 Calibration Instrument 3.2.5 Thermostat: Accuracy ±0.2°C
3.2.6 Cleaning agent: Does not change the properties of the elastic roller. 3.3 Testing conditions Testing should be performed at room temperature of 23 °C ± 2 °C, usually using a thermostat maintained at a temperature of 31 °C ± 1 °C.
3.4 Adjustment of the viscometer 3.4.1 After the viscometer is installed, the elastic roller must be stabilized before testing, and the adjustment repeated until the test data of the reference ink sample or the connecting material shows an unacceptable value.
3.4.2 Before normal use, the instrument should be calibrated according to the instructions provided by the instrument manufacturer. Use known standard inks or binders for the performance of materials used for calibration.
3.4.3 If the test ink or the connecting material has an effect on the ink roller material (for example, radiation drying ink), a special isolation device should be used.
3.5 Preparation of the sample The test sample is required to have stable properties and the particle fineness conforms to relevant national standards.
3.6 Test Method 3.6.1 Turn on the instrument power, adjust the thermostat to 31 °C ± 1 °C, and keep it at a constant temperature.
3.6.2 Apply the sample evenly to the elastic rubber roller with the ink injector, rotate the motor, and evenly transfer the sample to the metal roller and the uniform ink roller. The amount of injected ink or binder should meet the manufacturer's recommendations.
Note: The manufacturer's recommended ink injection volume will give the best ink film thickness and the most stable test results. The following is the ink volume recommended by several manufacturers, for reference, these inks will produce ink film thickness from 4μm to 13μm.

Viscometer Batta Tech 2000 Prufbau Inkomat Prufbau Tackomat Tack-o-scope Thwing-Albert Inkomat Toyoseiki Inkograph
Ink injection (ml) 1.00 1.00 0.55 0.30 1.32 1.31

3.6.3 Start the viscometer, and inhale the ink at a low speed for 10 seconds. Then turn the instrument shift lever to the measurement speed, then even the ink for 20 seconds. Hang the balance lever, adjust to balance, read the sticky value after 1 minute.
3.6.4 If you need to measure the tack value when the instrument is operating at medium and high speed, move the instrument shift lever to the middle or high speed position. The test procedure is the same as the low speed.
3.6.5 If it is necessary to measure the viscosity increase of the ink, continue to rotate the instrument while maintaining the original condition and read the viscosity value for 15 minutes. The difference between the tack value at 15 minutes and the tack value at 1 minute serves as a tack value.
3.7 Immediately after the cleaning test, clean the rollers and the ink injector with a suitable cleaning agent.

4 test result report

The report should include the following:
- specimen label;
- tack value;
- room temperature;
- thermostat temperature;
- Sticky instrument model;
- the amount of sample or ink film thickness used;
- roll surface speed, unit: m/min or revolution/min;
- Even ink time
- the time of reading data;
- Records of non-standard conditions;
- test date;
- The operator's name.