Main features of various inks

(1) Letterpress ink

Letterpress inks include: letterpress book ink, letterpress rotary book ink, letterpress color ink, letterpress plastic ink, rubber letterpress plastic ink (ie flexographic plastic ink), letterpress water ink, letterpress rotary press ink, etc.

Lead printing book ink is mainly used for printing books and periodicals, but also book printing ink. When printing books and periodicals on a flatbed machine, the ink is a penetrating dry ink with a certain degree of blackness. of the printing press. Book papers have a rough structure, but they have good oil absorption properties, so penetrating drying inks are used.

Lead printing color inks are often used in copperplate color printing, and some are called copperplate inks. When printing, it is carried out with a small flat-type printing machine, so the pressure is relatively large and flat, and the printing dots are mainly used, so the transfer performance of the ink is required to be good, the ink film layer in the dots should be uniform, and the fixation of the ink should be Fast, the ink film layer does not spread after embossing, so that the dots on the printed product have good contrast and contrast, and the imprint is consistent and full.

This type of ink should have a relatively low yield value, with a certain fluidity and viscoelasticity. Once the ink is imprinted on the paper, it should be able to fix and dry immediately. Therefore, the binder of the ink is mainly infiltrated, fixed and dried by the oxidation conjunctiva and the solvent, which not only dries quickly, but also has good transferability of the ink.

Relief rotary press ink is also called press rotary ink. It should be adapted to high-speed printing, so press rotary ink should have good flow properties and low viscosity. Generally, he said that the faster the printing speed, the better the fluidity of the ink and the viscosity. also lower. Press web inks are typical penetration drying inks that are almost entirely dependent on the absorbing binder of the paper fibers for drying.

Letterpress web book ink is suitable for book web press with printing speed between flatbed machine and news web press.

In order to adapt to printing high-quality paper at high speed, penetration drying type or oxidation conjunctival drying type can no longer meet the requirements, and it is easy to produce poor dryness, poor adhesion, chalking, smearing, etc. In order to overcome these disadvantages, thermosetting ink is used. That is, during printing, after high temperature baking at 200 ~ 250 ° C, the solution in the ink escapes, so that the ink is fixed on the printed matter.

(2) Lithographic ink

Lithographic inks include various offset printing inks, lithographic iron printing inks, lithographic photosensitive iron printing inks, collo printing inks, offset thermosetting inks, ptfe for water based ink etc.

One of the characteristics of offset printing ink is that the color tinting strength of the ink is higher. Because offset printing is indirect printing, the ink imprint on the printed matter is very thin, and only a strong tinting strength can meet the requirements. Because the printing speed is getting faster and faster, The ink should have good flow properties and good drying properties. According to the characteristics of offset printing, the ink should have good water resistance, so the water resistance of the pigment in the ink is very high. Most of the lake pigments are soluble in water and will cause fouling. If the binder is hydrophilic and emulsified, it will cause poor ink transfer and decrease in dryness. The resin-based binder is more water-resistant than the oil-based binder.

(3) Gravure ink

Gravure inks include various photogravure inks, engraving gravure inks, and gravure plastic film inks.

Photogravure ink is a typical volatile drying ink with the lowest viscosity among various inks. It has good fluidity and low surface tension, which is easy to fully fill in the concave holes of the printing plate. After printing, the ink can be transferred from the concave holes to the printing surface to the maximum extent, and the ink dries extremely quickly and thoroughly on the printed matter.

The characteristics of engraving gravure ink are thick but not sticky, loose and short, and have appropriate thixotropy. The ink should be easy to fill in the inking holes of the gravure, and it is easy to wipe off the ink on the blank part of the plane when wiping. Part of the ink should also be easy to transfer to the printed matter. After the ink is printed on the printed matter, the dots and lines of the graphic should not spread out and become larger, but should dry quickly.

The pigment expression of engraving gravure ink is mainly ink color, and transparent pigment cannot be used. Engraving gravure is mostly used in the printing of securities, so it has higher requirements on various properties of pigments, such as light resistance, water resistance, heat resistance, oil resistance, etc. In order to prevent counterfeiting, some special additives are often added to the ink.

(4) Stencil ink

Stencil inks include screen printing inks, screen plastic inks, oil-based transcription inks, and water-based transcription inks.

Because the imprint of silk screen printing is thicker by applying ink and pressing with a rubber squeegee, the communication characteristics of silk screen printing ink should be thick, loose and non-sticky, and the pigment content in the ink can be correspondingly less, so that the ink can be smoothly through the wire mesh.

The oxidative drying ink in the screen printing ink, after printing on the printed matter, the faster the drying, the better, and the volatile drying ink is heated to facilitate the evaporation of the solvent.

Transcription inks generally have less fluidity and less viscosity, mainly relying on penetration and drying.

(5) Special functional ink

①Microcapsule ink

Substances with special functions are sealed in capsules, inks are made with appropriate connecting materials, and printed in a way that does not destroy the capsules, so that the printed matter has special properties. For example, liquid crystal ink, which uses the difference of temperature and pressure to change the color of liquid crystal, is used to represent the numbers of thermometers and calculators; perfume ink is made of perfume into capsules, and the capsules are destroyed to emit fragrance; foaming ink uses foaming agent, After printing, it is heated and foamed for printing Braille and other printed materials.

②Gold and silver ink

Gold and silver inks use metallic powders instead of pigments. In the past, gold powder and silver powder were attached to the gold and silver ink. For gold and silver printing, the varnish is mixed with gold or silver powder just before printing, and there are also mixed inks. Brass powder is used for gold powder, and aluminum powder is used for silver powder, both of which are crushed from flakes to give metallic luster.

③Fluorescent ink

Fluorescent inks are inks using fluorescent pigments, which bring bright and strong color effects, so they are often used in eye-catching prints such as advertising paintings, packaging materials, advertisements, and exhibits. Fluorescent pigments dissolve fluorescent dyes in synthetic resins. In the medium, the particles are coarse and the light resistance is weak, and once irradiated by an ultraviolet lamp, a more brilliant effect can be obtained.

④Magnetic ink

Magnetic ink is an ink made of magnetic iron oxide powder. It is used for magnetic ink text reading, controlling the magnetic properties of magnetic powder, and reading from the magnetic beam emitted from the printed special literature and fonts. It is mainly used for printing credit cards. tape strip.

⑤Safety ink (anti-counterfeiting ink)

Security ink is an ink for printing various securities, and must have various excellent light resistance, heat resistance, water resistance and oil resistance. Gravure ink is one kind. In order to prevent counterfeiting and tampering, it must be matched with a compound that can see a special reaction, and it is also used as a security ink for ink disappearance, decolorization, discoloration, fading or color.

⑥Conductive ink

Conductive ink is an ink made of gold, silver, copper or conductive carbon black, and the dried ink layer has conductivity and is used for printing of printed circuits, electrodes, etc. Gold powder, silver powder and copper powder have their own electrical conductivity, but the price of gold and silver is too high, copper is easy to be oxidized, and carbon black is prone to differences due to the different properties of the raw materials used. A sort of.

⑦Copy ink (subpoena copy ink)

Printing is performed with a hot-melt type heat-fusing. Carbonless copying is colorless due to pressure, and the unnecessary copying part uses desensitizing ink, which reduces the contact during copying and loses the copying effect, and uses chemical functional materials that prevent color formation.

There are many other functional inks. There are monitoring inks that change color under the action of gas, temperature indicating inks that change color due to temperature changes, and color developing inks that change from colorless to colored under the action of light. Edible ink printed on food, pyrophoric ink printed on the friction part of matchbox, etc.