Ink Factors Affecting Print Gloss
1Ink film thickness
In the paper to maximize the absorption of ink after the linker, the remaining linker is still retained in the ink film, which can effectively improve the gloss of the print. The thicker the ink film, the more the remaining linker, the more conducive to improving the gloss of the print.
Gloss with the increase in the thickness of the ink film and increase, despite the same ink, but the formation of different paper print gloss with the thickness of the ink film and change is different. High gloss coating paper in the ink film is thin, print gloss with the increase in ink film thickness and reduce, this is due to the ink film masks the paper itself original high gloss, and the ink film itself formed by the gloss and due to the paper absorption and reduce; with the gradual increase in the thickness of the ink film, the paper on the absorption of linking material is basically saturated after the increase in the number of linking materials retained on the surface, and the gloss is constantly improving.
Coated cardboard prints gloss with the increase in ink film thickness increases very quickly, in the ink film thickness increased to 3.8μm after the gloss will no longer increase with the increase in ink film thickness.
Ink fluidity is too large, the dot increases, the size of the print is expanded, the ink layer becomes thin, printing gloss is poor; ink fluidity is too small, high gloss, ink is not easy to transfer, but also not conducive to printing. Therefore, in order to get a better gloss, should control the fluidity of the ink, not too big not too small.
In the printing process, the ink leveling is good, then the gloss is good; poor leveling, easy to pull, then the gloss is poor.
4Pigment content in ink
The high pigment content of the ink can form a large number of tiny capillaries within the ink film. And these large number of fine capillary retention of the ability to link material, than the paper surface of the fiber gap to absorb the ability to link material is much larger. Therefore, compared with inks with low pigment content, inks with high pigment content can make the ink film retain more linker. The gloss of printed matter using inks with high pigment content is higher than that of inks with low pigment content. Therefore, the capillary network structure formed between the ink pigment particles is the main factor affecting the gloss of the print.
In actual printing, the use of gloss oil method to increase the gloss of the print, this method is completely different from the method of increasing the pigment content of the ink. These two methods to increase the gloss of the print in the application, according to the components of the ink and printing ink film thickness to choose.
The method of increasing the pigment content is limited by the need for color reproduction in color printing. Ink formulated with small pigment particles, when the pigment content decreases, the gloss of the print decreases, only when the ink film is quite thick to produce a high gloss. Therefore, the method of increasing the pigment content can be used to improve the gloss of the printed matter. However, the amount of pigment can only be increased to a certain limit, otherwise it will be due to the pigment particles can not be completely covered by the linking material, so that the ink film surface light scattering phenomenon is aggravated instead of leading to a reduction in the gloss of the printed matter.
5Size of pigment particles and degree of dispersion
The size of pigment particles in the dispersed state directly determines the state of ink film capillary, if the ink particles are small, it can form more small capillary. Increase the ability of the ink film to retain the linker and improve the gloss of the print. At the same time, if the pigment particles are well dispersed, it also helps to form a smooth ink film, which can improve the gloss of the print. The governing factors affecting the degree of dispersion of pigment particles are the pH of the pigment particles and the amount of volatile substances in the ink. The dispersion of pigment particles is good when the pH value of the pigment is low and the content of volatile substances in the ink is high.
6Transparency of ink
After the ink film is formed by the ink with high transparency, part of the incident light is reflected by the surface of the ink film, and the other part reaches the surface of the paper and is reflected again, forming two color filtration, and this complex reflection enriches the effect of the color; while the ink film formed by the opaque pigment is only glossy by the reflection of the surface, and the effect of the gloss is certainly not as good as that of the transparent ink.
7Gloss of connecting material
The gloss of the connecting material is the main factor of whether the ink prints can produce gloss, the early ink connecting material to linseed oil, tung oil, catalpa oil and other vegetable oils, the smoothness of the surface of the film after the film is not high, can only show the fat film surface, the incident light to form a diffuse reflection, the gloss of the print is poor. Nowadays, the connecting material of the ink is mainly composed of resin, and the surface smoothness of the ink after coating is high, and the diffuse reflection of the incident light is reduced, thus the gloss of the ink is several times higher than that of the early ink.
8Drying form of ink
The same amount of ink using different forms of drying, the gloss is not the same, generally oxidized film drying than penetration drying gloss is high, because oxidized film drying of the ink in the film-forming linker material more.
How to improve print gloss?
1 Reduce ink emulsification
Reduce the degree of ink emulsification. Offset printing in the ink emulsification is mostly caused by the operation of water and ink, the print looks like a thick layer of ink, but the ink molecules into the state of oil in water, drying gloss is extremely poor, and will produce a series of other failures.
2 Appropriate additives
Add appropriate auxiliaries in the ink, you can adjust the printability of the ink in order to smooth printing. General auxiliaries added to the amount of ink, shall not exceed 5%, if you consider the effect of gloss, should be less or not put. But the fluorocarbon surfactant is different, it can prevent the ink layer of orange peel, wrinkles and other surface defects, and at the same time can improve the surface of the print gloss.
3 Correct use of drying oil
Correct use of drying oil. For high-level glossy quick-drying ink, in the case of temperature and humidity is normal, itself has enough drying capacity.
In case of the following situations, the drying oil should be added:
① In the case of low temperature and humidity in winter;
② ink must be added to the anti-adhesive, anti-adhesive, thin ink adjustment oil, etc., should be added to the drying oil.
In the process operation, the correct use of dry oil, for the formation of the finished product gloss is very favorable. This is because the paper to absorb the link material needs a certain amount of time, in the process, as soon as possible to make the link material cohesion, until the film is dry, is the key to the finished product gloss.
4 Machine Adjustment
Correctly adjust the machine. Whether the ink layer thickness of the print reaches the standard, also has an impact on the gloss. For example: poor pressure adjustment, dot expansion rate is high, the thickness of the ink layer does not meet the standard, the finished product gloss is slightly worse. Therefore, to adjust the pressure, so that the dot expansion rate control at about 15%, the printed product ink layer is thick, the level and pull open, gloss is also there.
5 Adjust the ink concentration
Add Fanli water (No. 0 oil), this oil viscosity is very large, thick, can adjust the ink concentration, so that the thin ink to thicken, increase the gloss of the printed product.
Post time: Aug-17-2023