The impact of ink on print gloss and how to improve print gloss
Time:2024-06-05
Views:461
Ink factors that affect the gloss of printed matter
1、Ink film thickness
After the paper maximizes the absorption of ink binder, the remaining binder is still retained in the ink film, which can effectively improve the gloss of the printed matter. The thicker the ink film, the more remaining bonding material, the more conducive to improving the gloss of the printed matter.
The gloss increases with the increase of the thickness of the ink film, although the ink is the same, the print gloss formed by different papers varies with the thickness of the ink film. When the ink film of high gloss coating paper is thin, the gloss of the printed matter decreases with the increase of the thickness of the ink film, which is because the ink film covers the original high gloss of the paper itself, and the gloss formed by the ink film itself decreases due to the paper absorption. With the gradual increase of the thickness of the ink film, after the absorption of the paper to the binder is basically saturated, the surface retention of the binder increases, and the gloss continues to improve.
The gloss of coated paperboard printed matter increases quickly with the increase of ink film thickness, and after the ink film thickness increases to 3.8μm, the gloss will no longer increase with the increase of ink film thickness.
2、Fluidity of ink
The fluidity of the ink is too large, the dot increases, the imprinting size expands, the ink layer becomes thinner, and the printing gloss is poor; The ink fluidity is too small, the gloss is high, the ink is not easy to transfer, and it is not conducive to printing. Therefore, in order to get a better gloss, the fluidity of the ink should be controlled, not too big or too small.
3、Ink leveling
In the printing process, the ink leveling is good, then the gloss is good; Poor leveling, easy drawing, poor gloss.
4、The amount of pigment in the ink
The pigment content of the ink is high, and a large number of small capillaries can be formed in the ink film. The ability of these large numbers of small capillaries to retain the binder is much greater than the ability of the fiber gap on the surface of the paper to absorb the binder. Therefore, compared with inks with low pigment content, inks with high pigment content can allow the ink film to retain more binder. Prints using inks with a high pigment content have a higher gloss than prints with inks with a low pigment content. Therefore, the capillary network structure formed between ink pigment particles is the main factor affecting the gloss of printed matter.
In the actual printing, the method of applying gloss oil to increase the gloss of the print is completely different from the method of increasing the pigment content of the ink. These two methods of increasing the gloss of printed matter should be selected according to the composition of the ink and the thickness of the printing ink film when applied.
Due to the need of color reproduction in color printing, the method of increasing pigment content is limited. For inks formulated with small particles of pigment, the gloss of the print decreases when the pigment content is reduced, and a higher gloss can be produced only when the ink film is quite thick. Therefore, in this case, 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, because the pigment particles can not be completely covered by the binder, the light scattering phenomenon on the surface of the ink film will be aggravated, but the gloss of the print will be reduced.
5、The size and dispersion of pigment particles
In the dispersed state, the size of pigment particles directly determines the state of ink film capillaries, and more small capillaries can be formed if ink particles pee. Increases the ability of ink film to retain binder and improves the gloss of printed matter. At the same time, if the pigment particles are dispersed well, it also helps to form a smooth ink film, which can improve the gloss of the print. The limiting factors that affect the dispersion of pigment particles are the pH value of pigment particles and the content of volatile substances in ink. The pH value of the pigment is low, the volatile substance content in the ink is high, and the dispersion of the pigment particles is good.
6、Ink transparency
After the ink with high transparency forms an ink film, 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 out again, forming two color filters. This complex reflection enriches the color effect; The ink film formed by the opaque pigment, its luster is only reflected by the surface, and the luster effect is certainly not as good as that of the transparent ink.
7、The luster of the connection material
The gloss of the connecting material is the main factor to produce the gloss of ink imprinting. The early ink connecting material is mainly vegetable oil such as linseed oil, tung oil and catalpa oil. The smoothness of the surface behind the conjunctiva is not high, and it can only show a fatty film surface, forming a diffuse reflection of the incident light, and the gloss of the imprinting is poor. And now the ink connection material to resin as the main component, imprinting conjunctiva surface smoothness is high, the diffuse reflection of the incident light is reduced, so the luster of the imprint is several times higher than the early ink.
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8、Drying form of ink
The same amount of ink using different drying forms, its gloss is not the same, generally oxidized conjunctiva drying gloss is higher than osmotic drying, because oxidized conjunctiva drying ink in the film forming binder.
How to improve print gloss?
1、Reduce ink emulsification
Reduce ink emulsification. The excessive emulsification of ink in offset printing is mostly caused by large amounts of water and ink in the operation, and the ink layer looks very thick, but the ink molecules have become a state of oil in water, and the luster is very poor after drying, and a series of other failures will occur.
2、Add adjuvant appropriately
Adding appropriate auxiliary agents to the ink can adjust the printability of the ink for smooth printing. The amount of general additives added to the ink, not more than 5%, if considering the luster effect, should be less or not put. However, fluorocarbon surfactants are different, which can prevent the ink layer from appearing orange peel, wrinkling and other surface defects, while improving the gloss of the printed surface.
3、Use dry oil correctly
Use dry oil correctly. For advanced bright fast drying ink, under the condition of normal temperature and humidity, it has enough drying capacity.
If the following situations should be added to the drying oil:
① In the case of low temperature and humidity in winter;
② The ink should be added in the case of anti-stick agent, viscosity removal agent, thin ink oil, etc., should be added to the drying oil.
In the process operation, the correct use of dry oil is very beneficial to the formation of gloss in the finished product. This is because the paper takes a certain amount of time to absorb the binder, and in this process, the binder condenses as soon as possible until the conjunctiva is dry, which is the key to the finished product‘s good luster.
4、Machine control
Adjust the machine correctly. Whether the thickness of the imprinted ink layer meets the standard also has an impact on the gloss. For example: poor pressure regulation, high dot expansion rate, ink layer thickness is not up to standard, and the finished luster is slightly poor. Therefore, the pressure should be adjusted well, so that the expansion rate of the dot is controlled at about 15%, the ink layer of the printed product is thick, the layer is pulled open, and the luster is also there.
5、Adjust ink concentration
Gavanli water (No. 0 oil) This oil viscosity is very large, itself thick, can adjust the ink concentration, so that the thin ink thickens, increase the gloss of the printing product.
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Anna Zhang