Talk about gold silver ink and its printing techno

With the development of society, the relevant data obtained from experiments are as follows: the improvement of exhibition and living standards, as well as the rapid progress of today's printing technology, people have higher and higher artistic effects on packaging decoration and color layout. Gold and silver are not only printed on cigarette packets or wine labels, but also on the cover or body of some high-end publications and exquisite picture books, so as to improve the quality of products. Gold and silver ink can show the luster of metal, giving people a solemn, luxurious, dazzling, magnificent feeling. Its product imprint is fine and solid, with strong covering power, and floating feeling. It has excellent visual effect. It is the first choice for color rendering and embellishment in the printing of high-end packaging and commercial publications

I. composition of gold and silver ink

like other inks, gold and silver ink are mainly composed of pigments and binders, that is, gold ink is made of gold powder and silver oil, and silver ink is made of aluminum powder and silver oil

pigment is the colored substance in the ink, which gives the ink a certain color. The pigment in gold and silver ink is ground from metal powder (i.e. gold powder and silver powder). The pigment in gold ink is gold powder, which actually has a particle size of 50 μ m～100 μ M copper zinc alloy powder (mainly copper), the content of zinc in gold powder is generally between 8% and 30%. The color of gold ink will vary with the content of zinc. Gold ink with zinc content between 8% and 12% is red in color, which is traditionally called red gold; These obvious reactions in the production of cathode materials in 2017, the gold ink with zinc content between 20% and 30% has a blue color, which is generally called green gold; Between red gold and green gold is called green red gold. Silver powder is actually aluminum powder, which is composed of 65% flake aluminum powder and 35% volatile hydrocarbon solvents. Aluminum pigment has a small specific gravity and is easy to float in the liquid. Silver powder has different particle sizes, so the metallic luster produced is also different. The silver powder with coarse particles has stronger reflection gloss, while the silver powder with fine particles has weaker reflection gloss. Silver ink used for printing, generally with particle diameter of 64 μ m～128 μ M aluminum powder

binder is the liquid component in ink. It is the carrier of pigment, so that powdered pigment particles can be evenly dispersed in it. At the same time, it also acts as an adhesive, so that the pigment can finally be fixed on the surface of the substrate material. Binder largely determines the viscosity, viscosity, fluidity, adhesion and drying performance of ink. Therefore, the quality of binder directly affects the performance of ink. The binder used in gold and silver ink is a special ink blending oil, which is generally called gold blending oil or silver blending oil. Its main components are oil, resin, organic solvents and other materials. Gold silver ink binder has the following performance requirements: ① it must have enough viscosity to combine well with gold powder or silver powder. ② Transparency must be high and cannot affect the hue of gold and silver ink. ③ The acidity of gold blending oil or silver blending oil should be low, otherwise it will react with gold powder or silver powder. ④ Gold oil or silver oil should have fast drying and fast fixation to prevent the back of gold ink or silver ink printing from sticking

plasticizers, antioxidants, desiccants and other auxiliary materials are usually added to gold and silver inks to improve the printability of inks

II. Characteristics of gold silver ink

1 Fineness of ink the better the fineness of ink, the better the dispersion of pigment particles. Compared with the pigments in other inks, the pigment particles of gold silver ink are thicker, which is easy to block the holes on the plate cylinder in the gravure printing process, resulting in plate blocking and a decrease in the ink transfer rate. During offset printing, it is also easy to accumulate on the ink roller, printing plate and blanket, resulting in the decline of printing plate resistance, blanket damage and other faults. Therefore, when blending gold and silver inks, try to choose gold and silver powders with high fineness and good floatability, so as to facilitate uniform blending and good imprinting

2. Gloss of ink the gloss of gold silver ink is largely related to the particle size of gold powder or silver powder. Generally, the larger the particle, the better the gloss of the ink; On the contrary, the gloss of ink is poor. However, with the increase of metal pigment particles, the printability of gold silver ink will also decline, the transfer performance is relatively poor, and it is easy to produce paste, so the particle size of gold powder and silver powder should be balanced

3. Compared with the pigments in other inks, the gold and silver powders in gold and silver inks have the characteristics of high conductivity and heat conductivity. Gold ink has poor heat resistance and is easy to change color in case of heat, so high temperature and heat accumulation should be avoided during use; Silver ink has good light and heat reflection performance, good heat resistance, and is not easy to change color under high temperature conditions

4. Chemical properties the chemical properties of gold ink are not stable enough, and different degrees of chemical changes will occur in contact with acids, bases and sulfides, which greatly reduces its metallic luster and shows blackening phenomenon; Secondly, gold ink is also easy to react with air and water vapor to cause discoloration. Therefore, when storing gold ink, we must seal and cover the container tightly. The chemical properties of silver ink are relatively stable, but silver ink is not acid resistant and is easy to react with acidic substances, which reduces the metallic luster of imprinting. Therefore, neutral auxiliary agents should be used to adjust ink in the printing process

5. Weight of ink ordinary ink is generally made of organic pigments and binders, but gold silver ink is composed of copper powder and silver powder with high density and binders. When using, it is necessary to ensure the stability of the ink and the good dispersion of gold silver powder, so as to avoid the precipitation of powder particles and the paste phenomenon during printing. Only gold powder or silver powder with better suspension can improve the metallic luster of gold silver ink. And the adhesion of gold and silver ink is poor, so the process requirements must be strictly followed when using it, otherwise it is difficult to obtain satisfactory gold and silver ink printing products

III. deployment and color change of gold and silver ink

generally, boxed ink can be used. If the amount is large, gold and silver ink can also be prepared by ourselves to save cost. Gold and silver inks can be obtained by using 30% - 50% gold powder or silver powder, and 70% - 50% silver oil or gold oil. The printing suitability can be adjusted by adding some auxiliary raw materials according to the agreement of both parties

when using gold powder that is generally converted into negative difference, gold powder with high fineness and low floatability should be selected, which is conducive to mixing evenly with solvent during printing and obtaining better imprinting. When preparing gold ink, the dilution and consistency of gold ink should be determined according to the printability of the substrate and the changes of climate and seasons, and different auxiliary agents should be applied to enhance the affinity, adhesion and fluidity of gold ink, so as to improve the adsorption performance of gold ink, so as to improve the transmissibility of gold ink. The use of silver powder is generally to choose 400 ~ 1000 mesh silver powder. The silver ink prepared with 1000 mesh silver powder has a relatively poor metallic luster, while the silver ink prepared with 400 mesh silver powder has a better metallic luster, which is very suitable for large-area printing products. However, silver powder is not acid resistant and will react chemically when encountering acidic substances to reduce the luster of the metal. Therefore, neutral auxiliary materials must be used in ink mixing and printing

when changing the ink, in order to ensure the purity of the ink, it is necessary to clean the ink roller first, apply some yellow ink after cleaning, and then clean it again; When printing silver ink, apply some white ink and clean the ink roller again to prevent color deviation. After the ink roller is completely dry, the ink can be printed to avoid ink failure