Classification and main components of printing inks

Ink is an important material for printing.

Ink is a homogeneous mixture composed of colored bodies (such as pigments, dyes, etc.

01 Classified by different drying methods

1) Oxidized conjunctival drying ink

2) Permeation drying ink

3) Volatile dry ink

4) Radiation drying ink

5) Wet solidification and dry ink

6) Condensation drying ink

7) Precipitation drying ink

8) Two-component reaction drying ink

9) Gelled drying ink

10) Filter drying ink

11) Dry type ink combined with multiple methods

02 Classified by printing process

1) Lithographic printing ink

Lithographic printing ink (referred to as lithographic ink) is a kind of viscous ink with a certain viscosity, most of which are oxidized conjunctival drying ink, which must have good water resistance

2) Letterpress printing ink (referred to as letterpress ink)

It is a kind of viscous ink, and its viscosity varies widely, which is related to the printing speed of the printing machine

3) Flexographic printing ink

It is a very dilute ink.

4) Gravure printing ink (referred to as gravure ink)

It can be divided into two categories, one is gravure ink, and the other is engraving gravure ink

5) stencil printing ink

It is required to have good fluidity, low viscosity, low viscosity, fast passing through the mesh, rapid penetration and drying after transfer to the surface of the absorbent substrate, and good adhesion on the surface of the non-absorbent substrate

03 The requirements of different printing materials for ink

1) Newsprint

The embossing ink used for newsprint printing is a kind of ink with very thin, low viscosity and good fluidity.
Its fluidity depends on the speed of the printer
.
The drying is completely absorption and penetration drying
.
Nowadays, news printing has been replaced by letterpress printing with rotary offset printing.
Flexographic printing has also been used in news printing.
Water-based inks have been used extensively in flexographic printing
.

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2) Coated paper and paper with surface treatment

For relief printing and sheet-fed offset printing, the thickness of the ink printed on coated paper should be thicker than that of uncoated paper, and the ink viscosity should be a little larger.
The final drying of the ink is mainly achieved by oxidizing conjunctiva; the rotary machine is on coated paper When printing, it is required to use fast-drying ink, and at the same time, oxidized conjunctival drying ink is gradually replaced by thermosetting ink
.

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3) Uncoated paper

The quality of uncoated paper varies, and the ink used must also be adapted to the requirements of various papers
.
It is usually printed with viscous ink, but it is thinner than the ink used for coated paper.
Its drying method is realized by permeation absorption and oxidized conjunctiva
.

4) Cardboard

Commonly used to make cardboard boxes, cartons, printed packaging, hardcover book covers and so on
.
In printing, the ink requires good fluidity, low viscosity, and can withstand the impact of mechanical forces such as collisions during handling and ink sassafras
.
All printing methods can be used for printing on cardboard: relief printing or offset printing with dry oxidized conjunctiva, gravure or flexographic printing with dry penetration and volatilization
.

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5) Some other papers

04 Composition of printing ink

Printing ink is a paste-like colloid that is uniformly dispersed and mixed by pigments, binders, fillers and other materials
.
The colorant gives the printed product colorful tones; the binder acts as the carrier of the colorant and also acts as a binder to fix the colorant on the surface of the substrate; the filler imparts appropriate properties to the ink, so that the ink can meet the printability of various printing processes
.

The ink should have certain fluidity, and meet the properties required by various printing processes, and be able to dry quickly on the printed product.
The dried ink film should have corresponding various water resistance, acid resistance, alkali resistance, light resistance, rub resistance, resistance to abrasion and the like
.

1) Connecting material

The binder is a viscous fluid.
Its function is firstly as a carrier of the pigment, mixing and connecting solid particles such as powdered pigment; secondly, as a binder so that the pigment can finally be fixed on the surface of the substrate.
achieve display text, images, marks, decorative purposes
.
The binder to a large extent determines the viscosity, viscosity, dryness and fluidity of the ink
.
To get high-quality inks, high-quality binders must be used
.
The main components of the binder are oil (vegetable oil, mineral oil), resin, solvent and auxiliary materials
.

2) Additives

Due to the variety of printing conditions, and in order to enable printers to actively adapt to changing printing conditions, use good inks, and improve printing quality, it is inevitable to add several ink additives with specific properties to the ink
.

Ink additives can improve certain properties of inks.
For example, plasticizers can increase the plasticity of polymer materials and make the ink film more flexible; diluents can make the ink thinner, increase the fluidity of the ink, and reduce the fluidity of the ink.
The viscosity of the ink; the viscosity-removing agent is also called the viscosity reducing agent, which can reduce the viscosity of the ink without affecting the body of the ink; the drier (desiccant) can accelerate the drying speed of the ink; the purpose of the thinning agent is to dilute The color of the ink is also called the lightening agent; the purpose of the degelling agent is to prevent the gelation, thickening and agglomeration of the ink; the anti-drying agent (antioxidant) can delay the oxidation polymerization process of the drying oil; the anti-contaminant ( Anti-smudge agent) can prevent the ink on a printed product from smudging to the back of another printed product; surfactants can improve the dispersibility of solid components and prevent their aggregation and precipitation; preservatives can extend the storage time of water-based inks; defoaming The agent can eliminate the bubbles generated during the use of the ink; the ultraviolet absorber can improve the lightfastness of the printed matter
.

3) Pigments and dyes

The colored materials used in printing inks are usually pigments, but some dyes are also useful
.
Both pigments and dyes are colored substances with extremely fine particles
.
Pigments are generally insoluble in water and binders, and most of them are called suspended states in solution; dyes are generally soluble in binders
.
The pigment must have high tinting power, hiding power, chemical stability, light resistance and other properties, and at the same time, the dispersion ability in the binder must be high
.
Commonly used in printing inks are inorganic pigments, fillers, organic dyes and dyes
.