Screen Printing 150 Questions (71-75)

â–¼71. How is the screen printing ink classified?

There are many kinds of screen printing inks, and their classification methods are also varied. However, the main classification methods are as follows.

1 According to the characteristics of the ink classification According to the characteristics of the ink can be divided into fluorescent ink, bright ink, fast fixing ink, magnetic ink, conductive ink, fragrance ink, UV drying ink, sublimation ink, transfer ink and so on.

2 According to the state of the ink

A. Colloidal ink: water-based ink, oil-based ink, resin ink, resin ink, starch paste and so on.

B. Solid ink: toner for electrostatic screen printing.

3 According to printability classification

A. Paper inks: oil inks, water-based inks, high gloss inks, semi-gloss inks, evaporative drying inks, naturally drying inks, coated paper inks, plastic synthetic paper inks, board paper carton inks.

B. Fabric inks: water-based inks, oil-based inks, emulsion inks, etc.

C. Wood ink: water-based ink, oil-based ink.

D. Metal inks: special inks for different metals such as aluminum, iron, copper, and stainless steel, including evaporative drying, oxidative polymerization, and two-liquid reactive inks.

E. Leather ink.

F. Glass inks: glass instruments, glass craft inks, etc.

G. Plastic inks: polyvinyl chloride inks, styrene inks, polyethylene inks, propylene inks; polypropylene, acetic acid, cellophane, and polymer resin inks.

H. Printed circuit board inks: Conductive inks, corrosion-resistant inks, electroplating-resistant and fluorine- and alkali-resistant inks.

I. Ceramic glassware ink.

4 According to the ink dry form classification

A. Volatile drying ink (including water-based inks).

B. Oxidation polymerization ink.

C. Two-fluid reactive ink.

D. Heat curing ink.

E. UV curing ink.

F. Electron beam radiation drying ink.

â–¼72. What are the composition of screen printing inks?

Screen printing inks are composed of colorants, binders, fillers and auxiliary ingredients. These compositions are reconstituted and ground into ink.

Each of the above-mentioned materials is made up of a variety of substances, each of which is of a different type. These are described as follows:

1 coloring material

A. Pigments and pigments are divided into various organic pigments, natural inorganic pigments and artificial inorganic pigments.
B. Dyes, dyes and water-soluble dyes, soluble in solvents and oil dyes.

2 link material

A. Natural resins, natural resins include rosin, shellac, rubber, and gum arabic.
B. Synthetic resins include rosin modified series, phenolic modified series, synthetic rubber, polyamide, etc., solid resins such as petroleum series and epoxy series; alkyd, epoxy, and acrylic liquid resins.
C. Vegetable oils, vegetable oils include tung oil, eucalyptus oil, linseed oil, and the like.
D. Solvents include alcohol series, ester series, fat series, petroleum series solvents, etc.

3 filling material

A. Natural fillers, such as terrazzo powder.

B. Artificial fillers include barium sulfate, calcium carbonate, colloidal calcium, and magnesium carbonate.

4 adjuvants

Adjuvants include driers, depressants, plasticizers, defoamers, emulsifiers, stabilizers, anti-settling agents, curing agents, and leveling agents.

â–¼73. What is a two-fluid reactive ink and what are its characteristics?

The ink that is mixed with a resin and a curing agent at the time of printing is called a two-liquid reactive ink. Epoxy-based resins are used in many of these inks, and curing agents use more ammonia. The advantages are: the solvent composition is very small, the adhesion to various materials is better, the ink film is hard and tough, with strong oil resistance, solvent resistance, heat resistance and so on. The disadvantage is that since the two solutions start to react after being mixed, the viscosity of the ink gradually increases during the printing process, and the ink after mixing cannot be preserved.

â–¼74. What is a heat curable ink and what are its characteristics?

The resin and curing agent are preliminarily mixed and then heated after printing so that the resin reacts to form an ink film. This ink is called a heat-curable ink. Although the characteristics of the film formed by the single-liquid type epoxy resin used for the resin of the ink are almost the same as those of the two-component type ink, the flexibility of the film is much different, since the ink is hardly at room temperature. Since the reaction is performed, it is easier to perform than the two-component type ink at the time of printing. But must use the high temperature above 150 °C barbecue, the ink is also difficult to save for a long time.

â–¼75. What is UV curable ink? What are its characteristics?

During the drying process, the ink is irradiated with ultraviolet rays to cause polymerization of the resin to form an ink film. This ink is called an ultraviolet curable ink (ie, UV ink). Ultraviolet ink is composed of a colorant, a prepolymer, a cross-linking agent, a photoinitiator, and an auxiliary agent. This ink mainly uses a photopolymerized photosensitive resin of a modified acrylic system prepolymer, and a photosensitive monomer, The photopolymerization initiator, the pigment and the auxiliary agent are mixed together so that the photosensitive resin forms the ink skin and the film according to the photopolymerization principle. Advantages: UV ink does not use any solvent, does not produce solvent volatilization in the printing process, is conducive to environmental protection and the health of workers, has good stability in the printing process, fast drying speed, saves heat, the film is shiny, color density Reproducibility is better than ordinary inks, with excellent abrasion resistance, water resistance, oil resistance and solvent resistance. Ultraviolet ink has a high flash point (above 100°C) and is not flammable. It is safe to use. Disadvantages: The UV light does not cure at the end, and the black part of the light absorption and the self part of the reflected light cure slowly. It is not the kind of material that can be bonded, and the cost of the ink is high.