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Testing Of Printing Ink Suitability

         Ink is an indispensable and important material for printing. It is a stable and uniform mixture composed of pigment as dispersed phase and binder as continuous phase. Among them, the pigment gives the ink color, and the binder ensures the transferability, transmissibility and dryness of the ink. Testing Of Printing Ink Suitability

          According to the characteristics of packaging printing process, the ink can be divided into lithographic printing ink, gravure printing ink, flexographic printing ink and screen printing ink. In the printing process, in order to test the printability of ink, some conventional performance tests need to be carried out, and the test items of different ink types are also slightly different.Testing Of Printing Ink Suitability

Testing Of Printing Ink Suitability

      In the printing process, the ink is frequently separated, transferred, continuously pressurized and forcibly separated in a thin layer between the ink rollers, between the printing plate and the blanket, and between the blanket and the substrate. When separating, the ink molecules will inevitably produce a force to resist the separation of thin layers of ink, also known as the adhesion of ink. Testing Of Printing Ink Suitability

      The adhesion of ink is related to the thickness of ink layer and the speed of separation. If the ink layer is thick, the viscosity is greater; The speed is large, the viscosity is larger, and the adhesion can be measured by ink viscometer. The viscometer consists of two synthetic rubber rollers and a hollow metal roller (which can adjust the temperature by water circulation).Testing Of Printing Ink Suitability

      During measurement, start the machine without ink, adjust the balance, fill the ink sample in the specified ink injection pipe, and start the machine for preheating to raise the temperature to 32 ℃. After shutdown, evenly add the ink in the ink injection pipe to the synthetic rubber roller, close the ink string roller and test again.Testing Of Printing Ink Suitability

        After inking for 30 seconds, hang the L-scale bar, and adjust the balance of the scale bar again with the weight on the L-scale bar within 30 seconds. Read the value on the scale, i.e. the tack value of the measured ink.Testing Of Printing Ink Suitability

       On the basis of measuring the ink viscosity value, the ink viscosity meter can rotate the instrument for another 15 minutes to measure the adhesion increment. Subtracting the adhesion value of 1 minute from the adhesion value of 15 minutes is the increment of adhesion. The more value-added, the better the inkiness of the ink.Testing Of Printing Ink Suitability

3. Fineness detection

        The fineness of ink is an important index affecting the printing quality. Ink is a system in which fine particles are evenly dispersed in binder. The thickness of these solid particles is called the fineness of ink. The fineness of offset printing ink is generally required to be ≤ 15 μ m; Fineness requirements of high-grade fine ink ≤ 5 μ m。Testing Of Printing Ink Suitability

      The fineness of printing ink is generally measured by scraper fineness meter. There is a deep to shallow groove in the middle of the fineness meter, and the deepest is 50 μ M or 100 μ m. 0 at the shallowest point. The groove edge is engraved with a scale indicating the depth of the groove.Testing Of Printing Ink Suitability

       First, take 0.5ml of the ink to be tested and dilute it with No. 6 ink blending oil. Add 18 drops (0.36ml) if the fluidity is less than 24mm; Add 14 drops (0.28ml) if the fluidity is between 25-35mm; Add 10 drops (0.20ml) if the fluidity is between 36-45mm; The fluidity is more than 46mm without dilution.Testing Of Printing Ink Suitability

       Pick up the diluted ink with the ink adjusting knife, place it in the deepest part of the fineness meter groove, place the scraper vertically and horizontally in the deepest part of the fineness meter groove ink, hold the scraper vertically, and scrape it evenly from top to bottom until it stops at zero point. Testing Of Printing Ink Suitability

      The fineness meter is tilted to the light source at an angle of 30 °, and the initial value of particle dense points is inspected with a 5-10 times magnifying glass. More than 15 particles within the scale range are the upper scale lines, and no more than 15 particles are the lower scale lines$ Page break$

Performance test of flexographic printing ink   Testing Of Printing Ink Suitability

      Flexographic printing ink is determined by the short ink path of its anilox roller. It belongs to a fluid close to Newtonian fluid, with good fluidity and viscosity of only 0.1-1.0p. Flexographic ink is generally volatile and dry. When paper or paperboard is used as the substrate, it is fixed by penetration.Testing Of Printing Ink Suitability

      The viscosity of flexographic printing ink is mainly measured by Ford cup viscometer. During the test, block the small hole under the small cup with your hand, fill it with ink, release your hand to let the ink flow out when there are no bubbles, and count with a stopwatch. Testing Of Printing Ink Suitability

      The time “s” used for all the fluid to flow out represents the viscosity of the ink. The longer the flow out time, the greater the viscosity.

       The fineness of flexographic ink shall be ≤ 20 μ m。 The color and coloring force are tested by densitometer and colorimeter after printing the sample sheet with flexographic suitability instrument.Testing Of Printing Ink Suitability

       Flexographic printability tester is composed of scraper, anilox roller, ink supply device and printing device, which can test the printability of flexographic printing ink.Testing Of Printing Ink Suitability

       The printing pressure, the number of lines added by the anilox roller and the printing speed are adjustable, so the flexographic inks with different viscosities can be detected. Testing Of Printing Ink Suitability

      The pressure of anilox roller of flexographic printing suitability instrument is adjusted between 30-500n; The printing pressure is adjusted between 30-500n; The printing speed range is adjusted between 0.3-1.5m/s.Testing Of Printing Ink Suitability

Performance test of gravure printing ink

       Gravure printing ink has low viscosity, close to Newtonian fluid and good fluidity. The test method of gravure ink is basically the same as that of flexographic ink.

       When testing gravure ink with flexographic printer, adjust the printer to gravure state. The method is as follows: while starting the machine, “enter”, a menu will be displayed after the power is turned on, press 1 to select “Settings”, press 3 to confirm,.

      a menu will appear, and select “grave mode” Select “1” as gravure printing status and “0” as flexographic printing status; After selection, press the 3 key to confirm and enter the printing state to detect.Testing Of Printing Ink Suitability

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