Second, ink properties

1. The leveling property of the ink, in the printing process, the leveling property of the ink is good, then the glossiness is good; the leveling property is poor, the drawing is easy, and the glossiness is poor.

2. The fluidity of the ink, the fluidity of the ink, the enlargement of the print size, the enlargement of the dot, the thin ink layer, the poor glossiness, the small fluidity of the ink, the reduction of permeation, the flattening of the ink film, and the glossiness of the printed product high. However, the ink flow is too small and the ink is not easy to transfer, which is not conducive to printing. Therefore, in order to obtain better gloss, the degree of fluidity of the ink should be controlled, increasing the viscosity or reducing the flow must all consider other printing conditions, otherwise simply emphasizing the gloss of the print will cause other quality problems.

3. The fineness of the ink, the coarse ink particles, the piles and other faults appear in the printing, the printed products are also rough, diffuse reflection occurs, and the gloss is poor. Conversely, gloss is better, and care should be taken when choosing the ink (especially gold ink, silver ink).

4. The viscosity and viscosity of the ink should not be too large or too small. If it is too large, the surface of the blanket and the printed product will be peeled and drawn. If the size of the ink is too small, the size of the print will be enlarged and the ink layer will be thinned, which will affect the glossiness. Greater China Graphic Arts Network

5. The dry form of the ink, the same amount of ink used in different forms of drying, the gloss is not the same, the general oxidation of the conjunctiva drying is higher than the permeability of the drying gloss, because the oxidized conjunctiva dry ink printing surface material more, and infiltration drying The surface of the ink print has less material. When the ink is transferred to the paper, the solvent part of the link material penetrates into the paper at a faster rate. At the same time, the coating and the paper fiber absorb the link material. The more rough the paper, the absorption ability of the link material is also The stronger it is. In the case where the oxidized conjunctiva is not yet dry, the binder is absorbed by the paper fibers. The remaining small amount of binder and pigment particles adhere to the surface of the paper, thus making the product dull.

6. The amount of driers added to the ink. In addition to the drying properties of the ink itself, the amount of driers added to the ink is also a factor that determines the gloss of the imprint. Due to the increase of the driers, the drying speed can be increased accordingly and the penetration time of the ink layer can be reduced. For example, cobalt driers are mainly used to promote oxidized conjunctiva, and it is suitable to use it. It is fast drying, smooth surface conjunctiva, and has the effect of increasing gloss. The disappearance of gloss is often due to excessive drying time. The absorption of ink by the paper and the penetration of the ink into the paper increase, resulting in the separation of the binder and the pigment. Part of the binder in the ink penetrates into the pores of the paper, making the binder in the The proportion of paper on the surface is reduced. If the infiltration phase is completed as soon as possible, the gloss of the dried ink layer can be improved. On the contrary, the surface of the ink film is diffused and matte.

7. Ink transparency, high transparency of the ink to form the ink film color layer, the incident light part of the ink film surface reflection, the other part of the surface of the paper, and then reflected out to form two color filter, this complex reflection mechanism is rich The effect of color, the opaque pigment formed by the color layer ink film, its gloss is only the surface reflection, the gloss effect is certainly not as good as the transparent ink.

8. The gloss of the binder, the main components of the ink are binders and pigments. The gloss of the binder is a major factor in the ability of the ink blot to produce gloss. The early ink binders were made from vegetable oils such as linseed oil, tung oil, and eucalyptus oil. The surface smoothness of the blotted conjunctiva was not high, and only the fatty film surface was observed. Diffuse reflections were formed on the incident light, and the gloss of the blot was comparable. difference. Now the binder of the ink is mainly composed of resin. After the conjunctiva is blotted, the surface smoothness is high, and the diffuse reflection of the incident light is reduced. Therefore, the gloss of the blot is several times higher than that of the grease and ink.

9. The viscosity of the ink on the adsorptive force between the binder and the pigment. The viscosity of the ink is related to the adsorption force between the binder and the pigment. Increasing the viscosity increases the adsorption between the binder and the pigment. Absorption will be reduced accordingly, so that the reduction in the amount of penetration, the better the gloss, so an appropriate increase in the viscosity of the ink can make the gloss of the print increases.

10. The thickness of the ink layer, the total thickness of the ink surface of the ink sheet has a great relationship with the gloss. Generally, the gloss of a single color print rarely occurs, and if it is overprinted, it will have a luster. Therefore, the thickness of each ink layer is correct. Glossiness has an effect. For example, a thicker layer of ink can lay a foundation for improvement of glossiness. When the number of color registrations is large, the paper surface can be filled and glossiness can be improved.

11. The emulsification of ink, the emulsified ink, must begin to dry after the water evaporates, so the drying is delayed, and many small holes are formed on the surface of the ink layer, which reduces the gloss of the print.

Third, printing pressure

Pressure is the key to a good transfer of prints. Pressure is too high, prints are enlarged, and glossiness is weakened; pressure is too small and prints are not clear, which can result in dull prints. Therefore, under the premise of ensuring that the ink on the blanket can be correctly transferred to the printing material during offset printing, the minimum pressure should be used as much as possible so as to print the glossy printing product.

Under the same paper and ink conditions, due to the problems in the operation process, the gloss of finished products often differs greatly after printing. Without considering the treatment of post-printing, the following methods can be used to increase the gloss of printed products:

1. Improve the acidic wetting fluid. Our country has used acidic wetting liquids for decades, mainly chromic acid and phosphoric acid. Although diluted, the pH is still between 3.5 and 5.6. The stronger the acidity, the greater the decomposition force and corrosive force on the ink binder and the pigment, resulting in rougher surface of the imprinted film and reduced gloss. For the research and development of wetting fluids, breakthroughs have been made in recent years. For instance, Shanghai's “Lydtex Wetting Powder” can be said to be effective. Now our country's offset wetting fluid has entered a new stage, but some printing The factory is still using the old formula.

2. Reduce the degree of ink emulsification. Excessive emulsification of the ink in offset printing is caused by large amounts of water and ink in the operation. The ink layer on the imprint looks very thick, but the ink molecules become oil-in-water, and after drying, the gloss is extremely poor, and a series of other malfunction. Water, ink and more is the most taboo practice in offset printing. To change this situation, in addition to the quality and technical education that should always be performed on operators, we recommend the use of "Lide wet powder," because the agent has better wetting properties. Even if the layout moisture is small, it is not easy to get dirty. It is both beneficial to the operation and makes the finished product glossy.

3. Appropriately add auxiliary agent in ink. Adding appropriate auxiliary agents in the ink 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. For example: anti-adhesive 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 rough, the finished product is poor. Another example is the addition of No. 6 thin varnish, which not only increases the fluidity, but also increases the permeability of the blot on the paper, and also reduces the drying, which is detrimental to the gloss of the print. Therefore, the amount of ink added to the general adjuvant must not exceed 5%. If the gloss effect is taken into consideration, it should be kept less or not. However, fluorocarbon surfactants are different. They can prevent surface defects such as orange peel and wrinkles in the ink layer, and at the same time, can improve the gloss of the surface of the printed product.

4. Use dry oil properly. For high-gloss, fast-drying inks, they have sufficient drying capacity under normal temperature and humidity conditions. In case of the following conditions should be added dry oil: First, in the winter when the temperature and humidity are low; Second, the ink must be added to the anti-adhesive agent, de-adhesive, thin ink, etc., should be added Dry oil. In the process operation, the correct use of dry oil is very beneficial to the gloss of the finished product. This is 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. Dusting powder, like ink, can also produce cohesion, especially in bags or drums that are badly sealed. After dusting, the powder is condensed into larger particles and sprayed on wet ink blots to make the surface of the ink layer rough and reduce. The original gloss, so dust should pay attention to moisture. In addition, there is a heating device on the mechanism of the powder spraying device, which should be inspected when using powder spraying, and whether the heating device is malfunctioning.

6. Adjust the machine correctly. Whether or not the thickness of the ink layer is up to the standard also has an effect on gloss. For example, poor pressure regulation, high dot gain rate, and the thickness of the ink layer do not meet the standards, and the gloss of the finished product is slightly poorer. Therefore, we must adjust the pressure so that the expansion rate of outlets will be controlled at about 15%. The ink layer of the printed product will be thick, the layers will be pulled open, and the gloss will also be there.

7. Add Fan water (No. 0 oil). This oil is very viscous, thick in itself, can adjust the ink concentration, thicken the thin ink, increase the gloss of printed products.

8. 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.

9. Add a lighter. When some inks are too dark to meet the requirements of spot color printing, they need to be lightened. This will not only make the ink lighter, but also improve the gloss of the prints.

10. Add 19# resin oil. When the ink fluidity and transfer performance are not good, 19# resin oil can be directly transferred, which can not only improve the ink gloss, but also does not affect the progress of multicolor overprint printing.