Detailed printing paper and printing ink (5)

4. Various ink characteristics

(1) Letterpress ink

Toppan inks include: lead-printing inks, letterpress printing inks, color inks for lead printing, plastic inks for printing, rubber letterpress plastic inks (ie, flexographic plastic inks), letterpress inks, and letterpress printing inks.

Lead-print books and periodicals inks are mainly used for printing books and periodicals, and they are also book inks. When printing on books on the platform machine, the ink is a penetrating dry ink with a certain degree of blackness. The viscosity is lower, and the yield value is lower, so that it can be used evenly for ink rollers. Printing press. The structure of books and papers is relatively rough, but they have better oil absorption properties, so they use a permeable dry ink.

Printed color inks are often used in copperplate color printing, and some are called copperplate inks. When the printing is carried out with a flat-press type smaller printing press, the pressure is relatively large and level, and the printing dots are mainly used, so the ink transfer performance is required to be good, the ink film layer within the dots should be uniform, and the ink fixing should be Fast, the ink film layer is not spread after embossing, so that the dots on the printed product have a good contrast contrast, and the print is consistent and full.

Such inks should have a relatively low yield value, have a certain degree of fluidity and viscoelasticity, and once the ink is imprinted on the paper, it should be able to fix and dry immediately. Therefore, the ink binder is mainly composed of an oxidized conjunctiva and a solvent, which is infiltrated and dried. This not only results in fast drying, but also the transferability of the ink.

Relief wheel transfer printing ink is also called press rotation ink. To adapt to high-speed printing, press rotation ink should have good flow properties and low viscosity. In general, he said, the faster the printing speed, the better the fluidity of ink is required. The lower it is.

Newsprinting inks are typically osmotic drying inks that are almost completely dry depending on the absorbent fibers of the paper fibers.

The letterpress rotary printing ink is suitable for printing speeds between the platform press and the news rotary press.

In order to adapt to high-speed printing of high-quality paper, infiltration drying type or oxidized conjunctiva drying type can not meet the requirements, and it is easy to produce poor drying, poor adhesion, chalking, scumming, etc. To overcome these drawbacks, thermosetting inks are used. That is, in the printing, after baking at a high temperature of 200 to 250° C., the solution in the ink is removed, so that the ink is fixed on the printed matter.

(2) Lithographic ink

Lithographic inks include various offset inks, lithographic printing inks, lithographic printing inks, inks of the Sala version, offset thermosetting inks, and the like.

One of the characteristics of offset printing inks is that the color tinting strength of inks is higher, because offset printing is indirect printing, and the ink blots printed on printed matters are very thin. Only a strong tinting strength can meet the requirements, because the printing speed is faster and faster. The ink should have good flow properties and good drying properties. According to the characteristics of offset printing, the ink must have good water resistance, so the water resistance of the pigment in the ink is very demanding. Most of the lake pigments are soluble in water and cause dinging. If the binder is hydrophilic emulsified, it will cause poor ink transfer and dryness, and the resin type binder is more resistant to water than the oil type binder.

(3) gravure ink

Gravure inks include various photogravure inks, engraved gravure inks, gravure plastic film inks, and the like.

Photogravure inks are typical volatile dry inks. Viscosity is the lowest among various inks. It has good fluidity and low surface tension. It is easy to fill in the recessed holes of the printing plate. The ink has strong adhesion and ensures the paper pressure. After printing, the ink can be transferred from the recessed hole to the surface of the print brush to the maximum, and the ink is dried extremely fast on the print, and must be thoroughly.

The characteristics of the engraving gravure ink are thick and not sticky, it is loose and short, and it has appropriate thixotropy. The ink can not only easily fill in the intaglio printing ink hole, but also can easily wipe off the ink on the blank part of the printing plane during printing. Some of the inks should also be easy to transfer to the prints. After the inks are printed on the prints, the dotted line of the graphic should not spread out, but should be dried quickly.

The pigment expression of gravure inks is mainly ink-based and cannot use transparent pigments. Engraving gravure is more commonly used in the printing of negotiable securities, so the various performance requirements for pigments are high, such as light resistance, water resistance, heat resistance, and oil resistance. In order to prevent counterfeiting, some special additives are often added to the ink.

(4) Ink printing ink

Stencil inks include screen printing inks, screen plastic inks, oil type inks, water type inks, and the like.

Because the screen printing is thicker with the squeegee ink and pressure, the flow characteristics of the screen printing ink should be thick, loose, and non-tacky, and the pigment content in the ink can be reduced accordingly, so that the ink can be smoothly Through the wire mesh.

Oxidation-drying type inks in screen printing inks, printed on prints, the quicker the better, volatile drying inks use a heating process to facilitate solvent evaporation.

Ink printing inks are generally less fluid and less viscous, relying primarily on osmotic drying.

(5) Special function ink

Microcapsule inks, substances with special functions, are sealed in capsules, inks are made of suitable binders, and printing is done in such a way that the capsules are not damaged, so that the prints have special properties. Such as liquid crystal ink, the use of the temperature and pressure to change the color of the liquid crystal, used to represent the thermometer, the calculator's figures; spices and inks used to make capsules perfume, the capsule is destroyed when issued fragrance; foaming ink using foaming agent, After printing, it is heated and foamed to print Braille and other printed matter.

Gold and silver ink, metal powder instead of pigment. In the past, gold powder and silver powder were attached to gold and silver inks. For gold and silver printing, ink varnish is mixed with gold powder or silver powder just before printing, and mixed ink is also available. Gold powder used brass powder, silver powder with aluminum powder, all made of sheet crushed to give metallic luster.

Fluorescent inks are inks that use fluorescent pigments. They bring a vivid and intense color effect. They are often used in eye-catching printed products such as posters, packaging materials, advertisements, and exhibits. Fluorescent pigments are used to dissolve fluorescent dyes in synthetic materials. In the resin, the particles are coarse, and the light resistance is also weak. Once the ultraviolet light is irradiated, a more brilliant effect can be obtained.

Magnetic ink, ink made of magnetic iron oxide powder, used for magnetic ink character reading, controlling the magnetic properties of magnetic powder, reading from the magnetic beams emitted from the printed special literature and fonts, mainly used for printing credit cards On-chip tape.

Security ink (anti-counterfeiting ink) is a printing ink of various securities, must have a variety of excellent light resistance, heat resistance, water resistance, oil resistance, gravure ink is a kind. In order to prevent counterfeiting and tampering, it must be equipped with a compound that can recognize a particular reaction, as well as a safety ink that can be used to eliminate, discolor, discolor, fade, or color ink.

Conductive inks are inks made of gold, silver, copper or conductive carbon black. The dried ink layer is conductive and used for printing circuits, electrodes, etc. Gold powder, silver powder and copper powder have their own conductive properties, but the gold and silver prices are too high, and copper is easily oxidized. Carbon black has different properties due to its different raw material properties. Graphite crystals have the best conductivity and are the most commonly used. One.

Rewritable ink, voucher replication ink, and printing by hot-melt heating and melting. Carbonless copying is colorless due to pressurization, unnecessary copying uses desensitized inks, reduces repetitive contact and loses copying, and uses chemical functional materials that prevent coloration.

There are many other functional inks. There are monitor inks that change color under the influence of gas. There are temperature-indicating inks that change color due to temperature changes, and there are color-developing inks that change from colorless to colored under the effect of light. Food inks printed on foods, fired inks printed on the friction part of a match box, etc.


Source: China Screen Printing Technology Professional Network

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