In the process of ink printing, how to do with the poor luster of pile ink fading?
Time:2022-12-12
Views:2400
The fault caused by ink in offset printing accounts for a relatively large proportion, mainly in the following aspects:
Heap ink
The ink pile fault caused by ink refers to the accumulation of ink in the ink roller, printing plate or blanket, ink transfer is poor. Pile ink in addition to paper causes, is the ink, printing pressure and plate pressure. The ink accumulates on the blanket, and the pigment is powder in a separate state. The dot paste is dead, and the color seems inconsistent. This is because:
(1) poor ink dispersion, ink used in the relative density is too large coarse particles inorganic pigment.
(2) ink film is too thick.
(3) ink dilution is excessive, linking material is too thin.
(4) Printing pressure is not real, the roller ink transmission performance is poor.
In practical printing work, white ink, gold ink, silver ink is the most prone to heap ink failure inks.
Treatment method:
(1) Check the printing pressure, roller performance and liner.
(2) the amount of ink should be appropriate, if the ink is too soft, some thick ink can be used.
(3) Change to new ink.
In practical printing work, white ink, gold ink, silver ink is the most prone to heap ink failure inks.
There are many factors causing the failure of stack ink, offset printing press operators must make clear the cause of the failure, do not mention the stack ink fault that is caused by ink.
Printing poor luster, not bright
Printing luster is poor, not bright, in addition to the paper factors, mainly due to excessive ink dilution, resin precipitation and loss of connection, slow drying ink or paper absorption is too strong, resulting in ink infiltration into the paper and print uneven and dull.
Treatment method:
(1) Add new ink or add bright linker in ink.
(2) Change with high gloss ink or with poor absorption of paper.
(3) Add some desiccant appropriately.
(4) The printed matter can be treated with gloss oil.
Another manifestation of poor print luster is "whitening". This fault is mostly in the process of volatile dry printing ink printing, and a transparent white ink film appears in the process of rapid solvent volatilization after high-speed printing. This phenomenon is sometimes temporary, but most can be long-lasting. This is because the cooling (device) near the drying print ink film is blown or the air is cooled to the dew point, that is, the water (vapor) is absorbed and returned to the picture ink film and condensed. In addition, such as ink system solvent or pigment water will also cause printing picture ink film luster poor.
The method of prevention is to adjust the solvent used in printing ink, reduce the amount of solvent that evaporates quickly, and control the relative temperature in the workshop air below 65%.
Fade
The colour of the ink fades during printing, or the colour of the ink fades during stacking (during drying) if:
(1) The heat generated by the oxidation of ink in the paper pile will make the ink color fade.
(2) the desiccant used in the ink contains too much cobalt.
(3) the pigment is not heat resistant or the pigment content in the ink is too small.
(4) with light color, white ink selection is not appropriate.
Treatment method:
(1) reduce the amount of desiccant, the use of fast drying (or fast solid) type ink.
(2) ink in the use of heat resistant, light resistant stable pigment.
(3) Change to white ink.
Fading is a failure in the printing process or printing in the outdoor aging stage. The ink film is exposed in the atmosphere. Due to the action of ultraviolet light, the degree of color change varies with the temperature, humidity, sunlight intensity and the nature and ph value of the printing ink film. Therefore, before printing, try not to choose easy to fade lake ink.
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