Gold and silver ink printing materials and application analysis (3)

(2) Offset Printing and Printing Silver Craft

Offset printing of gold and silver inks has the characteristics of high speed, simple process, and good results, so it is widely used in packaging and printing. Since the offset printing process utilizes the principle of ink incompatibility and ink balance, the gold and silver powders in the gold and silver inks have high density, large particles, and poor printability, and may cause problems such as discoloration due to the acidic wetting liquid. , should pay attention to these issues when printing.

1 Formulation of offset printing gold and silver ink

Field and line printing gold and gold ink. 1000 mesh gold powder 100g, gold oil 80g, transparent yellow ink 20g. Or 1000 mesh powder 200g, oil transfer 100g, dry oil amount.

In the field and line version, two gold and gold inks are printed. The first printing of gold ink: 1000 mesh gold powder 200g, gold oil transfer 200g, 05-25 transparent yellow ink 200g, suitable amount of dry oil; second printing gold ink: 1000 mesh gold

Powder 200g, oil transfer oil 100g, 05-25 transparent yellow ink 100g, suitable amount of dry oil.

Net print gold gold ink. 40% of gold oil, 40% of clear light ink, and 20% of phenolic resin. After preparation of the linking material, 1000 mesh of gold powder is formulated with 1:1 gold ink.

Ancient paintings are printed in gold and gold ink. 24-1 resin 100g + gold oil 100g mixed first, then add 1000 mesh gold powder 200g, gold oil 3g, dry oil amount.

The proportions and technical specifications of gold powder and gold transfer oil should be taken into consideration when formulating offset printing gold inks, which should be adjusted accordingly based on changes in climate and environment around the country and the selected printing machinery.

Offset silver ink (by weight ratio). 60% silver paste and 40% silver adjustment ink, among which the composition of the silver ink mainly composed of resin is: 70% of phenolic resin and 30% of linseed oil; the composition of silver oil mainly composed of bright oil

For: Bright oil 35%, dibutyl phthalate 62%, red dry oil 3%.

2 Offset Printing Gold Printing Silver Fountain Solution Selection

The wetting fluid should be acidified occasionally because of the tendency of the black and gold powder to become black due to the acidic dampening solution. It is suitable to use alcohol type wetting liquid, because the alcohol type wetting fluid has less oxidation of gold and silver powder, gold and silver powder is not easy to change color, the water consumption of the wetted layout is small, and it is easy to reach the ink and ink balance.

The amount of wetting fluid used in the layout should be controlled to the minimum water standard under the premise of “no paste”. Excessive water volume makes the gold and silver inks emulsify and affect the printing quality.

Linings should be neutral or rigid. Because the lithographic offset printing speed is fast, the contact time of the printing plate cylinder and the blanket cylinder, the blanket cylinder and the paper is short, and the transfer performance of the gold and silver ink is poor, and the ink layer needs to be flat and thick. Therefore, it must be solved by increasing the pressure. However, in order to increase the pressure and soft pack lining and easy to compress and deform, causing the gold and silver dots to enlarge and paste, the medium and hard liners are generally used to achieve both the purpose of reducing the compression deformation of the liner and increasing the pressure.

The color sequence of gold and silver ink printing is ranked in the last color. The reasons are as follows:

If gold and silver are printed on the front of the color sequence, when the viscosity of the latter color ink is greater than the previous color, it is easy to peel off some of the gold and silver ink of the previous color, resulting in less ink, dark and light, and color mixing.

If gold and silver are printed on the front of the color sequence, the gold and silver ink must be oxidized and discolored again due to contact with the wetting liquid one or more times after one or more colors are printed.

The bottom ink must be printed thick and flat. In addition, gold and silver inks must be superimposed when the bottom ink is dry and dry. The so-called non-dry refers to when the hand touches the bottom ink layer feels a certain degree of stickiness, but the ink is not sticky.

3 color sequence selection

Printing sequence of four-color offset printing press

The printing sequence of the four-color offset printing machine is generally black, cyan, magenta, and yellow, and the transfer of the printing ink of each color is performed in a state of “wet and wet” under high-speed operation. If the thickness of the ink layer printed on the paper is greater than the thickness of the ink layer on the blanket of the latter unit, the ink layer breaks on the paper, and the ink on the blanket is not transferred to the paper. Instead, it will accept the printed ink from the previous color. Produce a "reversal" phenomenon. This “wet-wet-press” method of overprinting brings a lot of inconvenience to the printing of gold ink and silver ink, and the printed effect is not very satisfactory.

In order to overcome the above unfavorable factors, using the four-color offset printing machine to print gold ink, silver ink can take the following solutions to increase the amount of ink (that is, increase the ink layer thickness) when printing gold ink, silver ink can eliminate the "reversal" phenomenon. However, the fine hollow text is easy to paste, it is difficult to operate, and waste of ink, increased printing costs.

A color plate with a short tone and a thin printing ink layer is placed on the former unit of the printing ink ink set.

Printing sequence of monochrome offset printing press

The single-color offset printing press is a color ink after the previous color ink layer is substantially dry, and uses the “wet-press-dry” overprint method. It does not pay much attention to the arrangement of the color sequence, and there is no four-color offset printing press. All problems with wet printing. In the case of printing gold ink and silver ink, the ink transfer rate of the monochrome offset printing press is higher than that of the four-color offset printing press in the case of equal transfer. That is to say. With a single-color offset printing machine, the ink is easy to pile up, and the ink layer is much thicker than the four-color machine. Due to the different overprinting modes, the monochrome offset printing press provides favorable conditions for the printing of gold ink and silver ink.

The advantages of printing gold ink and silver ink with a monochrome machine are:

Speed ​​up the drying of the print.

Reduce the ink penetration, with less ink can reduce the cost of printing to restore the truth.

Prints have high gloss and good visual effects.

The disadvantage is that the print production cycle is longer than using a four-color offset press.

The semi-finished products printed by the monochrome machine can not be put for a long time, otherwise it is easy to produce crystallization phenomenon, resulting in the subsequent color ink printing is not on.

Lining influence selection

The four-color offset printing machine has higher requirements for the rubber and lining when printing gold ink and silver ink. Because the four-color offset printing machine has a high printing speed, the contact time between the back color ink and the front color ink layer is very short, and it is easy to cause Pulling hair and gold and silver ink paste version failure. This requires both increased printing pressure and excessive deformation. So you can only use medium and hard linings to achieve both reduced compression deformation and

Increase the purpose of printing pressure.

Its advantages are: due to the relatively large pressure generated by the medium and hard lining, it accelerates the speed of the ink penetrating into the interior of the paper, and the ink does not float on the surface of the paper; the ink layer is even and smooth.

The disadvantages are: High requirements for rubber and lining, which increase the printing cost; and the operation is cumbersome.

4 lining problem of monochrome offset printing machine

Single-color offset printing machine in the printing of gold ink, silver ink on the rubber, lining the request is not high, because of its slower speed than the four-color machine, but also to take "wet pressure dry" overprinting. Therefore, gold and silver inks are easy to pile up on paper when printing. When using a monochrome machine to print gold and silver inks, neutral or soft linings can be used. Neutral lining, domestic blankets, plus lining or liners (higher hardness). A slight increase in pressure is good.

The advantages are: good lining suitability, lower printing cost, easy operation, thick ink layer. Shiny.

5 Problems to be aware of

Wet control: The fountain solution must not use red syrup, because it will make gold ink, silver ink oxidation reaction. There is a color change. Lost gloss. Available 'Lide' powder instead.

The best way to moisten: alcohol dampening. The advantages of the alcohol dampening are as follows: The alcohol wet solution has little oxidation to the gold ink and the silver ink; the alcohol wet version has a small water consumption and a large dampening area, and it is relatively easy to achieve the ink-water balance; the alcohol wet version can evaporate off. The heat generated by the high speed friction of the ink roller avoids the blackening of the gold and silver ink due to the high temperature.

The amount of gold and silver before printing: The pigment particles of gold ink and silver ink are relatively coarse. Compared with general color offset inks, they have the disadvantages of poor printing adaptability and low adhesion, so they are printed in gold ink. It is better to use a layer of background color before silver ink.

Different paper colors are different, there are blue light, yellow light, generally depends on the hue of the paper to match the background color.

Generally, the background color of gold is mainly yellow, but it is also black. Silver printing is generally based on diluting the ink to make ink, or adding white ink to silver ink when silver is printed on the first pass. Afterwards, the second pass of silver was made.

6 Requirements for preparation of gold and silver

With the deployment of gold ink, the value of the ink-pumping oil used for silver ink is low. The varnish must be transparent. With fast drying, fast fixing performance. Gold ink should follow the ink with the tone, because the copper is easily oxidized, should be fully blended when adding gold powder, and kerosene should be properly added. When deploying silver ink. Generally about 57% silver paste, silver oil accounted for about 43%. Also add some kerosene properly.

7 Printability of gold ink and silver ink

Printing gold and silver printing should not be too small. Fine hollow text try not to use gold and silver ink printing. Need substrate color. As far as possible, coated paper, cardboard, etc. with high surface smoothness are used for large-area gold and silver ink printing. It is best to use a medium hard liner.

The pressure between the printing plate and the ink roller should be appropriately reduced to ensure that the printing gold and silver printing graphics are not deformed, and the pressure of the ink roller and the ink roller can be appropriately increased.

(to be continued)