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Chap.1 n Ink
1) Characteristics of ink
(1) Ink for the digital printer is an emulsion type. It has a water-in-oil type structure.
(2) The surface active agent has two characteristics: hydrophilic group and lipophilic group in one molecule.
Oil and water bond together by these two characteristics as shown in the figure.
(3) Ink
(3) Ink viscosity is high at a low temperature and it is low at a high temperature. So when ink is used at a
low temperature (10°C or less), the amount of ink transferred to the paper is smaller and the print
darkness is slightly lighter.
When ink is used at a high temperature (30°C or more), the amount of ink transferred to the paper is
larger and the print darkness is slightly darker.
INPORTANT :
• Precautions to be taken in handling ink
(1) Storage environment
• When an emulsion type ink is stored at too high or low temperature for a long time, oil and water in the
ink pack may be isolated. Keep the ink from too high or low temperature (5°C or less, 35°C or more).
Also keep the ink from direct sunlight since the temperature rises sharply in the direct sunlight.
• When the water content is frozen, the water content is solidified and the bond characteristics decreases.
• When ink is stored at a high temperature, the bond characteristics decreases due to the change of the
surface conditions (surface tension, solubility). The bond characteristics also decreases due to evaporatin
of the water content.
(2) Precautions to be taken in handling the ink pack
• When the ink pack is removed from the drum unit to store, put the ink pack with its mouth up, screw
the cap firmly after expelling air from the ink tube. (If air is in the ink pack, water content is generated.)
nInk
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