Gold and silver ink printing materials and technology application analysis (4)

The current gold and silver ink gravure printing is mainly used for plastic film or composite film printing. The use of gravure printing on plastic film printing gold and silver ink, unlike the lithographic, relief printing gold and silver ink on the paper. Paper has good adsorption to ink, and plastic film is different, its surface is smooth, surface tension is small, especially polyolefin film does not have extreme groups on the surface, chemical stability is good, the ink has adsorption. Therefore, to print gold and silver ink on plastic film, you must pay attention:

1 The surface of the plastic film is subjected to a treatment such as corona to improve the printability of the surface of the plastic film.

2 According to the characteristics of gravure printing and plastic film, use volatile dry special gravure gold and silver ink. Dedicated gravure gold and silver ink varnish is generally polyamide type. Its composition is: polyamide resin 40% to 50%, isopropyl alcohol 25% to 27%, xylene 25% to 28%.

3 using flat-panel printing gold and silver ink, the general ink first printed, and then printed gold and silver ink. The role of ink here is: First, the color, and second is to strengthen the adhesion of gold and silver ink. Gravure printing on plastic film

When printing gold and silver ink, you don't need to lay the ink at the end first, but use a color block in the graphic to play a role of color care and adhesion, so that the ink layer is full and the luster of gold and silver ink is increased.

4 Gold and silver inks should be used with the tune to clean the ink pump, pipe, ink tank and printing plate on time to prevent the reconciliation time from being too long, be discolored by oxidation, or be eroded by acids, alkalis and other chemical substances, or prevent the

Discolored gold and silver inks and undiscolored gold and silver inks are strung together. In order to avoid discoloration or cross-coloring, the printing artwork of gold and silver ink becomes dull, which seriously affects the metallic flash effect of gold and silver ink.

(4) Analysis of the causes of blackening of gold ink

Gold ink is made of gold powder. Gold powder will react with acids, alkalis, and other substances and change color. The main reason for the darkening of gold ink is:

(1) Inadequate storage of the powder, long-term exposure of the powder to air reacts with chemicals in the air;

(2) Gold ink is printed on non-coated paper and is in a high-humidity environment. The ink becomes ink due to the chemical action of sulfur compounds in the pulp and barium sulfate in the filler;

(3) The use of domestic coated paper and offset paper for printing gold ink is easy to black, the main reason being that papermaking uses acid-based papermaking technology, and the paper is acidic;

(4) The use of metal containers and tools to deploy gold ink black, it is appropriate to use porcelain, wooden containers deployment of gold ink; deployment of gold ink accessories should also use neutral materials;

(5) The overprinting of the semi-finished products of gold is too much. When the gold ink dries, the quantity of heat released by the ink is bad, and it accelerates the reaction between the gold powder, paper, and some of the chemicals in the ink and blackens.

(6) poor roller adjustment, uneven pressure, poor ink transfer performance, resulting in the printing process heap of ink, so that the gold ink stays on the roller, so that the powder by the long-term friction and the role of air and change the ink;

(7) When the ink is changed, the organic solvent of the cleaning ink fountain and the ink roller is not cleanly cleaned, so that the gold ink and the organic solvent react chemically to make the black ink black;

(8) When the printing press prints too fast, the friction of the ink roller increases, and the heat generated accelerates the reaction between gold ink and air and other chemical substances, which causes the ink to change ink;

(9) In the offset printing process, an acidic or alkaline dampening solution is used. These dampening solutions react with the gold ink to blacken the gold ink.

2.4.2.5 Common Faults and Exclusion of Gold and Silver Ink