How to distinguish the difference in the use of ink by ink viscosity?
In the packaging printing industry, often use a variety of inks, but different inks have different roles, from the viscosity to distinguish between the use of different ink differences.
1, the viscosity is relatively large, slightly less liquid “sticky” ink, its adhesion is good, the molecular friction or cohesion, strong adhesion, fast fixation, with “sticky” ink printing can get a clear and round dot, and The “sticky” ink is good water resistance, not easy to emulsify, there is a good “ink collection”, easy to dry, the network is clean, bright ink, color saturation, thick ink layer.
Therefore, this ink is more suitable for the following cases.
(1) for printing glossy, high surface strength of the paper, such as coated paper, glass cardboard, white cardboard and other paper, and gold and silver cardboard and other smoothness, non-absorbent paper is also applicable to the “sticky” ink.
(2) suitable for printing fine products with a high screen line, easy to obtain a strong and clear, full-color image.
(3) printing gold, silver ink, and printing fluorescent ink, also need to adjust the ink sticky some, so that its adhesion is strong and not dirty;.
(4) for phosphorus flake pearlescent ink, also need to adjust the sticky ink printing.
As the viscosity of the ink is an important factor influencing the network transfer, in practice, the size of the ink viscosity should be based on the changes in different conditions and the printing process to coordinate adaptation, make appropriate adjustments to increase or reduce the viscosity of the ink, which is actually a certain adjustment to the cohesion of the ink.
Make the ink viscosity to adapt to the actual printing conditions, the specific increase in “viscosity” adjustment methods are mainly.
(1) add the appropriate amount of viscosity enhancers to increase viscosity.
(2) add a high viscosity of the resin oil viscosity.
(3) add the appropriate amount of high-viscosity ink viscosity.
As the viscosity of the large “sticky” ink cohesion, strong adhesion, in some cases should not be used, for example: in the printing offset paper, white paper and other paper strength of the paper, printing speed, high ambient temperature, the layout of large field-based, etc., must use lower viscosity of the ink, if the ink viscosity is too high If the ink viscosity is too high, it is necessary to reduce viscosity processing.
Usually reduce the “viscous” methods are the following.
(1) add a certain amount of silicone oil.
(2) add 2% or less, up to 5% of the viscosity reduction agent to reduce viscosity.
(3) add high boiling point kerosene to reduce viscosity, the amount of control at no more than 10-20ml per kg.
(4) add a certain amount of corn starch, petroleum jelly and other viscosity-reducing substances.
2, thicker, but with a certain viscosity and adhesion of the “thick” ink, due to poor mobility, ductility is not good, the ink is paste, not easy to level, printing ink film is not easy to spread, graphic transfer is more accurate, not easy to deformation, ink color is more distinct and full. Therefore, “thick” ink is more suitable for the following cases: (1) suitable for printing large field, the ink film is not easy to spread, more accurate transfer of graphics, not easily distorted, the ink is more vivid and full.
(1) suitable for printing large field, with hollow words or with small words of the product, because it is not easy to level and spread, hollow words or small words are not easy to produce paste plate.
(2) suitable for printing large field with shallow dot products, can obtain a thick field, while the dot is relatively clear, not easy to expand: a. High ambient temperature, carriage, and other factors
a. high ambient temperature, slow speed, to the dot graphics-based situation, the general appropriate thickening of the ink for printing.
b. Paper surface strength is high, the surface of poor ink absorption, should also be appropriate to thicken the ink printing.
Actual production, if there is no corresponding consistency of the ink, or the consistency of the ink has become smaller, can not meet the requirements of use, it is necessary to increase the “thick” processing, so that the liquidity of the ink to reduce.
Specific increase “thickening” processing methods are mainly.
(1) add NaOH, adding 1%-3% or so, this method works faster, is a simple and effective way to thicken the ink.
(2) add viscosity enhancers, such as No. 0 ink oil, but pay attention to the amount of appropriate, not too much.
(3) such as the impact of temperature, the ink is not viscous enough, you can also add the same color phase of the original ink in the ink.
3, the consistency of a smaller, slightly less viscous ink, due to good flow, in the mutual squeeze of the ink rollers, can be well extended, good transfer performance, easy to ink, and ink in each printing transfer surface between the ink layer can quickly flow flat and spread, the ink film of the print flat service glossy, therefore, in some cases, also need to reduce the consistency of ink, such as
(1) paper quality is poor, relatively rough, ink absorption, or low surface strength, easy to pull off the powder, such as printing poor offset paper, booklet paper, white board paper, etc. use.
(2) When the layout is mainly field, large color block.
(3) when the workshop temperature is high and the printing speed is fast.
(4) the paper has broken phenomenon, if the ink is too thick, may make the breakage aggravated, so should use a little more liquidity of the ink printing.
The main ways to reduce the consistency of the ink are.
(1) add a certain amount of thinner
(2) diligently stir the ink hopper, because the ink is thixotropic, its flow characteristics will be improved with the increase in the degree of stirring, so that the ink viscosity is reduced.
(3) add 2% or less of viscosity reducer.
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