3. The impact of printing pressure on the gloss of the finished product <br> Printing pressure is the key to a good transfer of the printing, the pressure is too large, the imprinting is expanded, the glossiness is weak; the pressure is too small, the imprinting is not clear, and the printing product is dull. Therefore, under the premise of ensuring that the ink on the blanket can be correctly transferred to the printing material during the offset printing, the minimum pressure should be used as far as possible to print the glossy printing product.
Ways to improve gloss
Under the same paper and ink conditions, there is a problem in the process operation, which often results in a large difference in the gloss of the finished product after printing.
1. Improve the PH value of the fountain solution <br> China's use of acidic fountain solution for decades, mainly chromic acid, phosphoric acid, although diluted, but the PH value is still between 3.5-5.6. The stronger the acidity, the greater the disintegration and corrosion of the ink binders and pigments, resulting in the rougher surface of the imprinted membranes and reduced gloss.
2. Reduce ink emulsification
The ink emulsification in offset printing is mostly caused by the large amount of water and ink in the operation. It looks like the ink layer is thick, but the ink molecules form an oil-in-water state, and after drying, the gloss is extremely poor, and a series of other failures may also occur.
3. Add appropriate adjuvants <br> Add appropriate additives in the ink, you can adjust the printability of the ink for smooth printing. Most of the auxiliaries have an adverse effect on the gloss of the finished product. Such as anti-sticking agent, the main raw material for the six grain flour, adding ink, the surface of the imprinting film layer due to the precipitation of corn flour and become rough, the finished product gloss deterioration. Another example is the addition of No. 6 varnish, which not only increases the fluidity, but also increases the permeability of the imprint on the paper, and also reduces the dryness, which is detrimental to the gloss of the imprint. Therefore, the amount of the general adjuvant must not exceed 5% of the amount of ink. If the gloss effect is taken into consideration, it should be kept less or not. However, the fluorocarbon surfactant is different, it can prevent the occurrence of orange peel, wrinkle and other surface defects in the ink layer, and can also improve the gloss of the surface of the printed product.
4. Use dry oil correctly
For advanced bright and fast-drying inks, under the normal conditions of temperature and humidity, they have sufficient drying capacity and do not need to add dry oil. Need to add dry oil occasions, first, in the winter when the temperature and humidity are low; the second is the ink to add anti-adhesive agent, de-sticking agent, such as the thin tone of the oil, should add dry oil. The correct use of dry oil is very beneficial to the gloss of the finished product, because it takes time for the paper to absorb the binder. During this process, the binder is condensed as quickly as possible until the conjunctiva is dry, which is the key to good gloss.
5. Pay attention to dusting
Spraying powder, like ink, can also produce agglomeration, especially in poorly sealed bagged or bottled powders, which will aggregate into larger particles when wet, and spray onto wet ink blots to make the surface of the ink layer rough and decrease. The original luster. So dusting should pay attention to moisture. In addition, there is a heating device on the powder spraying mechanism. Please pay attention to whether the heating device is normal when using powder spraying.
6. Positive angle adjustment machine <br> Whether the ink layer thickness of the imprinted ink reaches the standard or not has an effect on the gloss. For example, poor pressure regulation, high dot gain rate, and ink layer thickness can not reach the standard. Therefore, we must adjust the pressure so that the dot enlargement rate will be controlled at about 15%, so that the ink layer of the printed product will not only be thick, but will also be able to pull off the level and have a good luster.
7. Other methods
a. Van Lib (No. 0 oil). This oil has a large viscosity and is thick and thick. It can adjust the density of ink, thicken the thin ink, and increase the gloss of printed products.
b. Add bright light. Bright paste is processed from raw materials with high gloss, which can increase the gloss of the ink, but the amount should not be too large, otherwise it will reduce the drying speed of the ink, resulting in sticky, brushed phenomenon, affecting gloss.
c. Add a lighter. When some inks are too dark and do not meet the requirements for spot color printing, they need to be lightened. Adding the withdrawal agent not only makes the ink lighter, but also improves the gloss of the prints.
d. Add 01-94 resin bright varnish (Valley name 19 # resin oil). When the ink fluidity and transfer performance are not good, they can be directly transferred in, not only can increase the ink gloss, but also does not affect the multi-color overprint.
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