The use and skills of specialty inks

Non-traditional lithographic offset inks, such as metallic inks, waterless inks, fluorescent inks, and opaque inks, have become increasingly popular among users as a design element and have the ability to improve internal throughput. When printing with non-traditional inks, the unique properties of each ink must be kept in mind so that the print settings can be adjusted to suit the specific situation to obtain the best print quality. This article describes some tips for using different specialty inks. It also describes how to choose the right fountain solution when using non-standard rubber, oil, and resin based inks.

Metal ink

Metallic inks are formulated from thin metal foils (aluminum foils are used for silver inks and copper foils are used for gold inks). When the inks are dried, these foils form a layer of stamped metal foil on the printed surface. When the metal pigment forms a thin layer on the surface of the print, it will produce a higher gloss of gold or silver ink. If you change the ink's metal flakes component or add color ink oil additives, the golden ink's color range will change from reddish gold to gold.

Metallic gold or silver inks have a long shelf life and do not lose their luster even if they are stored in a container for a year. However, the metallic inks in the PANTONE Metal Color Manual are not very stable and should be used as soon as they are bought or prepared. The use of softer particles for the formulation of metallic inks allows the metallic flakes in the ink to form a thin metal foil or to spread as far as possible on the surface of a single sheet of printing material for maximum gloss. Metal inks have low viscosity characteristics and are suitable for transfer between ink rollers, making the printing process cleaner.

The coated paper absorbs the fixed ink better, so the ink on which the ink is printed is the brightest. Smooth non-coated paper also gives better results, but the gloss is slightly reduced. The rough surface of the paper prevents fine metal ink particles from forming metal foil on the surface of the paper, thereby reducing the printing effect of the metallic ink.

Some substrates, especially polishing coating and clay-coated porcelain products, tend to hold the ink firmly on the surface of the substrate due to insufficient adhesion, often absorbing only the varnish in the ink. The particles stay on the surface. This phenomenon, known as "powdering," causes the metal color to peel off from the surface of the substrate. To prevent "powdering" from occurring, the amount of water should be set to a minimum. This is because inks with higher water saturation are more prone to "powdering." When printing on high coated paper or porcelain surfaces, an appropriate amount of desiccant should be added to the ink. Before printing with gold or silver ink, the surface of the substrate is usually sealed with a conventional oil-based clear white ink coated with a glue. If the "powdering" phenomenon has already occurred, printing another layer of ink on the surface of the first layer will often make up for this fault. Overprinting the varnish can also overcome powdering, but this tends to reduce the metallic luster.

Tip: For best results, it is recommended to use a metal plate instead of an electrostatic plate. This prevents the fountain solution from containing excessive amounts of glycerol or ethylene glycol because these non-volatile liquid media slow down drying.

The opacity of the metallic ink can cause the operator to compensate for excess ink, causing the ink to appear unbalanced. Should avoid this situation as much as possible, because it will give the dampening system too much burden, resulting in paste plate (ink particles emulsified in the fountain solution) and dirty (ink adhesion to the plate non-graphic section). Even experienced printers use the excess ink to achieve the perfect metal effect. The best way to prevent these malfunctions is to add ink to a lighter color image so that it covers the image exactly. Then, increase the amount of ink, and adjust the amount of water supply so that it is slightly higher than the minimum value, so as to avoid the non-graphic part of the ink. The thin layer of metal will protrude during the drying process, providing a brighter luster.

Fluorescent ink

When in a dark environment, fluorescent inks glow. The key to this effect lies in the fact that the ink contains a special color pigment that absorbs energy in the ultraviolet region and converts this energy into longer visible wavelengths. The surface of the print can emit a strong, saturated color that attracts attention.

The constituent particles of the fluorescent ink are generally softer than other oil-based or rubber-based ink particles. But this does not affect its performance, because they have a unique transfer method during the transfer of the drum and the drum, the plate to the blanket, the blanket to the substrate.

Tip: Fluorescent inks are best for metal plates. It is best not to use light or colored paper when selecting paper, because colored paper will be reduced, and even the brightness of the ink will be minimized. White or bright paper will enhance the fluorescence effect. Non-coated papers with higher brightness and better ink absorbability are preferably fluorescent inks. Coated white paper can also have a more beautiful effect. However, since only a small amount of ink is used for printing with coated paper, it is necessary to perform two printings for the best printing effect. Opaque Sunglasses Photochromic inks are mirror inks with a special effect. They are printed on a transparent plastic material (back side) and use light interference on the front to change the color of the ink as the viewing angle changes. To the effect of laser effects. Printed on a variety of substrates to get a unique sense of color and high-level sense. In recent years, there has been an increase in the use of mirror photochromic ink printing products, such as communicator buttons, electronic product panels, and plastic signs, etc., which are popular among users and have increased the value and selling point for silk screen printing products, but have been compared with ordinary printing inks. In contrast, such mirror-like photochromic inks require a high degree of printing techniques and techniques. Here's the characteristics of the mirror ink, printing method, storage and precautions, briefly described below, I hope to be able to use a good mirror ink to help:

1, the type of ink:

Divided into ordinary mirror ink (silver and metal colors) and mirror photochromic ink. General mirror inks have a wide range of applications, such as IMD technology used in mobile phone keypads, washing machine operation panels, microwave function indicator panels and signs, and decorative parts on electronic products; while the use of mirror light color inks are decorative It is even more superior to the ordinary mirror ink, making the product more beautiful.

2. The substrates used in surface inks are mainly transparent sheets, and they are printed on the reverse side (back side). The effect is seen on the front. The transparent sheets used are: PC (polycarbonate), PMMA (acrylic or plexiglass), hard PVC (polyvinyl chloride), and treated PET (polyester). The mirror ink has adhesiveness to the above-mentioned transparent sheet, and the mirror surface and mirror surface color change effect can be obtained. It is worth noting that PC or PMMA finished products, due to their different materials and processing techniques, some will be due to poor solvent resistance and can not get a good mirror or mirror change effect, so you must do a sample test before use, Confirmed before production. Not only that, in order to get a mirror effect, in addition to the above, because the mirror ink is a special aluminum powder pigment and a small amount of resin and other basic materials, and the aluminum powder pigment is a sheet, in the surface parallel to the mirror reflection performance Therefore, materials with poor surface smoothness (substrates) and materials that cannot withstand the solvents in ink are not able to obtain a good mirror effect.

3, screen printing mirror ink characteristics:

(1) In addition to a small amount of resin and flake aluminum powder pigments, the solvent accounts for more in the mirror ink, so the viscosity of the mirror ink is very low. When screen printing, as much as possible, do not use tilt-opening screen, otherwise the flow is more powerful. Therefore, regardless of manual or machine printing, parallel-elevation screens should be used to make the dilute, water-filled ink always full on the screen, so as to avoid or reduce the impact of screen-blocking and screen printing.

(2) If the screen printing machine is used for printing, the metal re-inking scraper should be replaced with a rubber-made re-inking scraper to make the ink evenly coated on the screen.

(3) When the mirror ink is screen printed, the range of coating on the web should be controlled as close as possible to the range of the printing area of ​​the effective graphics. Otherwise, due to the large coating area, the solvent in the mirror ink quickly volatilizes to cause blocking of the web and cannot be continuous. Printing and so on.

(4) The mirror-like ink is quickly volatilized on the Internet. To prevent blocking of the screen, be sure to print continuously while printing, and care must be taken not to allow the flowing air to dry the screen.

(5) Thickness of the ink film is too thick, the peeling phenomenon occurs between aluminum pigments in the ink. Therefore, it is recommended that the ink be printed as thin as possible. Note that the mirror ink cannot be overlaid and printed.

(6) Mirror-type ink itself does not have good shielding performance. In order to obtain a good mirror surface and its mirror color-changing effect, a layer of cover-type ink must be added. This type of printing ink should be coated with a mirror and a color-changing mirror ink. Solvent-free inks are not produced.

Mirror ink is a high-grade, decorative ink, thin as water, silk screen printing is also very volatile, if the printing environment is not good, printing technology is not in place, so there will be increased in the printing and blocking the number of network, but also Causes the ink on the substrate to be uneven.

Source: 21st Century Fine Chemicals Network