Analysis of the most popular situation affecting t

2022-07-14
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Analysis of the impact on the printing quality of gold and silver ink

gold and silver ink is colored by copper, zinc and aluminum metal powder, and granular metal powder is the main body of the ink. Therefore, the adhesion, viscosity and fluidity of gold and silver ink are worse than that of general ink, and it is easy to cause problems such as dark color, uneven ink color, imprinting crystallization, plate pasting, color fading, etc. Therefore, it is of great significance to correctly analyze the factors affecting the printing quality of gold silver ink and adopt corresponding technological measures to control the printing quality, so as to avoid blindness in operation and technology and improve the printing quality of gold silver ink

1 gold and silver ink lacks metallic luster

generally, the chemical properties of gold and silver powder in gold and silver ink are unstable. When encountering acid, alkali, sulfide gas or water vapor, a certain degree of chemical changes will occur, which makes the printing ink lack metallic luster. The color change law of gold ink is from golden yellow to brownish red, and then to black. In addition, the gold powder is easy to turn into copper carbonate under the process conditions of high concentration of carbonic acid gas and high humidity, so the gold ink on the printed products will gradually darken. The silver ink turns gray after changing color

in order to prevent the above situations, the gold and silver powders used for preparing gold and silver inks should be protected from heat, moisture and contact with acid and alkali substances during use and storage. The unused gold and silver powders should be well sealed to ensure the stability of their quality. In addition, if the gold and silver ink is mixed too much, used for too long, the printing machine rotates too fast, the number of rubber rollers is too many, and the contact pressure between ink rollers is too large, the ink is easy to oxidize and darken. If the pH value of the paper is in a partial acid state, such as offset paper, whiteboard paper and paperboard, it is generally partial acid. After printing, it is easy to have a chemical reaction, making the gold and silver ink layers on the paper lose their metallic luster

in order to reduce or prevent printing defects, gold and silver inks should be used at any time. Generally, the amount of one-time blending should be able to print continuously for threeorfour hours; The printing machine speed is controlled between 2500~3000 sheets per hour; It is better to use two inking rollers, and the gum should be a little softer; The height and front and rear positions of the inking roller shall be adjusted to avoid the ink oxidation and darkening due to excessive contact pressure and increased friction heat; Gold silver ink printing paper is better to use coated paper, glass paperboard and other paper with smooth surface

2 the gold silver ink on the printed matter is scratchy

1) the lining is uneven

if the lining is too soft or there are foreign objects left, it is impossible to maintain a comprehensive contact between the ink on each particle of the printing plate and the paper during the imprinting process, so the local printing plate is scratchy. In addition, the printing of relief plates of different sizes will make the lining uneven to a certain extent, so the silver ink lining should be neutral and hard, and the deformed and uneven lining should be replaced to improve the ink quality

2) the cot is too hard, the colloid is damaged or out of round

the cot is too hard, which is easy to cause uneven ink transmission; If the cot is not round or the cot surface is damaged, it will also produce uneven ink transfer and make the thickness of the printing ink layer different. Therefore, the colloid of the cot for printing gold and silver ink should be soft, the colloid should be intact and have a more accurate center degree, which is also an important condition for achieving uniform and full amount of gold and silver ink

3) gold and silver ink are too thin

if the proportion of gold, silver powder and gold blending oil is improper, that is, when the amount of gold blending oil is too large, the fluidity of gold and silver ink is too large, and its viscosity is also poor. During the printing process, the ink transmission and ink distribution will be too thin, so the color saturation is poor, and the imprinting will appear to be a little scratchy

4) the plate support is not solid, and the printing pressure is uneven

if gold and silver ink is printed by relief process, if the special device plate glued to each tool needs to be made separately is used as the plate support, the plywood has poor firmness, large compression deformation coefficient, and poor flatness, resulting in uneven printing pressure, so the printing ink layer is bound to be easy to flower. Therefore, it is advisable to use metal plate holders with good flatness, high hardness and firmness, such as magnetic metal plate holders and aluminum plate holders, to better improve the quality of printing ink

5) paper surface roughness

the brightness of the printing ink layer has a great relationship with the gloss of the paper surface. If the paper surface is rough and uneven, and the gloss is poor, the gold and silver ink will soon be adsorbed by the fiber tissue of the paper after printing, then the brightness of the printing ink layer is poor. For example, if the gold and silver ink is printed with offset paper, relief paper and white cardboard, the color rendering effect is bound to be unsatisfactory. Therefore, in order to ensure the printing quality of gold silver ink, it is advisable to use paper with good gloss such as glass card or coated paper to print gold silver ink

3 roughening and blurring of gold and silver plate

1) improper inking

the fluidity of ink determines the transmission effect and printing quality of ink. If the gold and silver ink is too thin or too thick, the imprint on the edge of the layout or on the anti white word is easy to accumulate ink and become thick or suffer from paste. So what is the appropriate viscosity for printing gold and silver ink? This is hard to say, nor can it be regulated by a unified standard. Because the structure and performance of the printing machine are different, and the printing ambient temperature conditions are different, the requirements for the concentration of printing ink are also different. Generally speaking, when the printing machine has many ink rollers, high speed and high printing temperature, the gold and silver ink should be properly thickened, so that the ink will just meet the printing requirements when it is relatively diluted when heated. If the ink is adjusted to the viscosity required for printing at once, the imprint will be easily diffused after the ink is diluted by heating during printing

2) too much ink

when printing gold and silver ink, if the ink output is too large, the ink layer on each ink roller is too thick, and after being applied to the printing plate, too much ink is retained in the graphic plate, our tepex products will not appear this kind of phenomenon in the stamping process, and the excess ink is bound to be squeezed to the graphic edge of the plate, making the imprint hair and paste. Therefore, printing gold and silver ink should control the amount of ink

3) the lining is weak and loose

the lining is not tight and tight, and there will be fuzzing marks on the edge of the imprinted version, so the lining process should be well controlled

4) printing pressure is too heavy

if the backing plate is not flat, or the bottom support plate is not square enough to cause the layout to be bow shaped or the backing plate pressure is too heavy, it will also cause the printing text to be blurred and thick. Therefore, the backing plate technology should be well controlled. The printing plate should be leveled, padded and of appropriate height

4 crystallization of the base color ink layer

1) the base color ink layer is excessively dried

when printing the base color ink, if the amount of drying oil is too large, the ink layer on the print will dry too fast and the gold and silver ink will not adhere when overprinting. Therefore, the amount of dry oil should be appropriate

2) the printing of the bottom color ink layer is too thick

the printing ink layer is thick, the brightness of the printing ink layer is high, and the visual effect is better. However, if the printing ink layer is too thick and the crystallization phenomenon is formed after the surface film is formed, it is difficult to overprint the gold and silver ink, and it is easy to pull off the ink layer after printing. Therefore, the thickness of the bottom color ink layer should be well controlled. Generally speaking, the bottom color ink layer with Overprint should be properly printed a little thinner, or even the bottom color ink should be relatively deepened to make the printing ink layer thinner

its connecting container is the evaporation condenser. 3) the overprint time interval is too long

if the printing sheet after the background color printing is placed for too long and the ink layer is too dry, the gold and silver ink overprint will not adhere. Even if it can be overprinted, the ink color will be blurred. In order to prevent this kind of situation, the base color ink is dried to 80% or 90% after printing, and the effect is relatively better

after the crystallization of the bottom color ink layer, remedial measures shall be taken to ensure the product quality. According to the experience summarized from the production practice, the base color ink layer can be wiped with a cloth to destroy the crystalline film to enhance the adhesion of gold and silver ink; Secondly, alkaline liquid or 389 resin oil can be added to the gold silver ink to process industrial soap; Third, properly increase the printing pressure of the gold silver ink layout to make the gold silver ink firmly adhere to the background ink

source: Printing World Author: tanghuiyu

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