Ink is an important material used for printing. It displays patterns and characters on the substrate through printing or ink-jet printing. The ink includes the main components and auxiliary components, which are uniformly mixed and repeatedly rolled into a viscous colloidal fluid. It is composed of binder (resin), pigment, filler, auxiliary agent and solvent. It is used for printing books and periodicals, packaging and decoration, building decoration, electronic circuit boards, etc. With the increase of social demand, the variety and output of printing ink also expand and increase accordingly
Chinese Name: Ink Purpose: Printing
Property: shape viscous colloidal fluid predecessor: ink

Ingredients: binder (resin), pigment, filler, auxiliary agent, solvent, etc

History:
China produced ink very early. The predecessor of ink is loose ink. In China, black ink is made from pine smoke, gum (mainly cow hide glue, which plays the role of bonding soot) and water. It was first used for writing, and later used in the wood printing industry. Ink developed rapidly in China in the early period. After the Middle Ages, it has been stuck in its own way, satisfied with traditional secret recipes, and not very original. At that time, the wood block printing in Europe was mainly water-based, but the application was poor, so it was changed to oil. Later, it evolved into modern printing ink. The development of printing technology has stimulated the development of the ink industry. There have been inks with multiple functions and high quality that meet various printing requirements
It is internationally recognized that China was the first country to use ink in ancient civilization. As early as the Western Han Dynasty (200 BC), China began to use ink. This ink can write on bamboo and silk to convey information, and some of its functions can be compared with contemporary ink
The development of printing ink and printing plate goes hand in hand, because the two do not match, the print will be unclear, and the ink film will fall off, affecting the printing quality. For example, the printing plate is in the period of woodblock engraving, and the ink is made by evenly mixing and drying the burnt wood carbon and gum, which is water-soluble. When printing, apply ink to the plate, place the paper on it, and then gently wipe it with a cloth or brush to transfer the images and texts on the plate to the paper through ink. In the period of metal plate, since water-based ink could not be evenly applied to the plate, oily ink was invented, which was made by evenly dispersing pigments in grease. The original ink pigment is natural inorganic mineral, and the binder is plant or animal fat. This kind of ink, drying speed is slow, printing gloss is poor, poor adhesion to substrate. With the development of the chemical industry, it has brought vitality to the ink industry. New synthetic resins and advanced organic pigments have been widely used in ink manufacturing, which makes the variety of ink more abundant and the performance more excellent. The development of printing ink has entered a new stage, and eventually the traditional lithography, letterpress, intaglio and screen printing all have a perfect and mature ink system
With the advancement of human civilization and the development of printing industry, substrate materials are constantly being developed and expanded, and printing methods are constantly innovating. The production process of printing ink is more sophisticated, and the types and varieties of printing ink products are increasing. For example, the promotion of waterless offset printing technology has increased the demand for waterless offset printing ink, and the rise of flexible digital printing has also made digital printing ink stand on the stage of history. There is also a strong call for environmental protection, which has triggered the re selection of ink raw materials and the reform of manufacturing process, such as water-based ink, soybean offset printing ink, UV ink, FB ink, etc. Ink, the biggest pollution source in the printing industry, is trying to reduce the volatilization of its organic substances and the application of harmful metals. We have reason to believe that the future development of the ink industry will move towards caring for life, embracing nature and a harmonious society
Main components:
Color pigment:
Pigments include pigments and dyes. Pigments can give ink different colors and color concentrations, and make ink have a certain viscosity and dryness. Azo and phthalocyanine pigments are commonly used
Binder:
Binder is made by dissolving a small amount of natural resin, synthetic resin, cellulose, rubber derivatives, etc. in dry oil or solvent. It has a certain fluidity, so that the ink can form a uniform thin layer after printing, and form a film with a certain strength after drying. It also protects the pigment and makes it difficult to fall off
Auxiliary materials:
Auxiliary materials include the two aspects that must be applied when making the binder and the application after the ink is made. The purpose is to adjust the printability and dryness of the ink and improve the printing effect
Filler:
Fillers are white, transparent or opaque substances. They are mainly used as fillers for pigments. They can not only reduce the amount of pigments used, reduce the cost of printing ink, but also adjust the fluidity of printing ink. They can also increase the thickness of printing ink film and improve its wear resistance. However, they do not have coloring power and hiding power. The filler shall be selected according to the colorant, mainly including barium sulfate, talc, kaolin, calcium carbonate, aluminum hydroxide, etc., which shall be ground into white powder when used
diluent:
The function of the thinner is to reduce the viscosity of the ink, prevent film peeling, and make the ink suitable for operation. The commonly used diluents are low polymerized amidine oil, mineral oil, etc. The former is easy to mix with ink and has a soft effect; The latter has obvious dilution effect, but avoid excessive use, otherwise the printing effect will be poor
Dilution agent:
The function of the diluent is to dilute the color of the ink. Light color ink is mainly prepared with diluent, and dark color ink is supplemented. Attention should be paid to the influence of diluent performance, and appropriate diluent should be selected according to the requirements of color sample transparency and product use. The common types of diluents include white ink, transparent oil and gloss paste. White ink has poor transparency and strong covering ability. The light color ink prepared has a powder texture, and is often used for field printing. Transparent oil, also known as Weili oil, is the first diluent used for offset printing ink. Transparent oil is a light yellow transparent oil. It will darken the color when mixed with some inks, such as golden red, light blue, etc. It also has the effect of inhibiting drying. Therefore, it is only used for the preparation of light colored inks that are generally required. Light color ink for fine products is usually prepared with bright paste. Brightening paste is a resin type diluent that is nearly colorless and transparent. It has good compatibility, has little influence on the color of color ink, and has strong water resistance, fast drying, and good conjunctival brightness. It is the most ideal diluent at present
Anti skinning agent:
The function of the anti skinning agent is to inhibit the drying speed of the ink and prevent the ink from drying the conjunctiva mechanically. The anti skinning agent is mainly composed of organic reducing agent and antioxidant, which can be added to the ink or spread on the machine contacting the ink
Anti reverse printing agent
The function of anti backprinting agent is to prevent the printing ink layer from backprinting to the back of the paper, so as to ensure the printing quality. The most commonly used anti reverse printing agent is corn starch
Smoothing agent:
The role of the plasticizer is to improve the friction resistance and fluidity of the ink, reduce the viscosity, improve the smoothness of the film, and reduce the paper galling. The commonly used lubricant in ink includes microcrystalline wax with high melting point, synthetic wax, etc
Other additives:
There are many other additives, such as dispersant, wetting agent, desiccant and stabilizer
Physical and chemical properties:
The physical and chemical properties of ink mainly refer to its density, fineness, transparency, gloss, light resistance, heat resistance, and acid, alkali, water, solvent (alcohol) resistance
Density:
Density refers to the weight of ink per unit volume at 20 ℃. It is expressed in g/cm3. The density of ink depends on the type and proportion of raw materials used in the ink, and is affected by the external temperature. The density of ink is related to the printing process. The density of ink is related to the amount of ink used in the printing process. Under the same printing conditions, the amount of ink with high density is greater than that with low density
The density of ink is too large, mainly because of the density of pigment in the ink. During the printing process, solid particles such as pigments are piled up on the surface of ink rollers, printing plates, or blanket, forming a blocking phenomenon, because the binder cannot drive the pigment particles with excessive density to transfer together. Especially in high-speed printing or when the ink is thinner, it is easier to use ink with high density. At the same time, when the ink with high density is mixed with the ink with low density, if the gap between the two is too large, it is easy to produce ink layering. The ink with low density floats and the ink with high density sinks, which makes the color of the ink surface favor the ink with low density and the color of the ink at the bottom favor the ink with high density. Generally, the density of printing ink is between 1g/cm3 and 2.25g/cm3
Fineness:
Fineness refers to the degree of dispersion of solid powders such as pigments and fillers in the ink in the binder, also known as dispersion. It shows the size of solid particles in the ink and the uniformity and degree of particle distribution in the binder. The fine degree of the ink indicates that the solid particles are fine, and the distribution of the solid particles in the ink is uniform. The fineness of the ink depends on the wettability of the binder to the pigment and other solids, and the fineness of the ink after mixing and rolling
The fineness of ink is a very important quality index, which relates to the printability of ink, such as rheology, fluidity and stability. The fineness of the ink is poor and the particles are coarse, which will cause blocking in printing. In offset printing and gravure printing, it will cause damage to the printing plate and scraper. Moreover, due to the uneven dispersion of pigments, the strength of the ink color cannot be fully exerted, which affects the dyeing power of the ink and the brightness of the dried ink film
Transparency:
Transparency refers to the degree to which the ink refracts (transmits) the incident light. Transparency in printing refers to the degree to which the background color of the object can be displayed when the ink is uniformly coated into a film. The transparency of the ink is low, and when the background cannot be fully displayed, it will cover the background to a certain extent, so this performance of the ink is also called the covering power. The transparency of the ink is inversely proportional to the hiding power. Transparency is expressed by the thickness of the ink layer when the ink completely covers a certain background color. The greater the thickness, the better the transparency and the lower the hiding power of the ink
Transparency depends on the difference between the refractive index of pigment and binder in the ink, and is related to the dispersion of pigment. The smaller the difference between the refractive index of the pigment and the binder, the better the dispersion of the pigment in the binder, and the higher the transparency of the ink
Glossiness:
Glossiness refers to the ability of the ink on the surface of the printing brush to reflect light in the same direction when it is dry. The ink with high glossiness shows great brightness on the printed matter. Glossiness mainly depends on the type and nature of the binder in the ink, the processing of the refining process in the ink manufacturing and the smoothness of the ink film after drying. In addition, the glossiness of the ink is also affected by the nature of the pigment in the ink composition, the size and shape of the particles, and the degree of dispersion; The influence of ink permeability, leveling, dryness and other properties; The influence of substrate, etc
Lightfastness:
Light fastness refers to the ability of the ink to keep its color unchanged under the sunlight. The light fastness of the ink indicates the degree of fading or discoloration of the printed matter under light irradiation. Although the ink with strong light resistance is exposed to sunlight for a long time after printing, the degree of discoloration of the printed matter is small; The printing materials of the ink with poor light fastness are easy to fade, or even the color will fade completely. In the classification of inks, grade 8 is the most difficult to fade and has the best light fastness. The lightfastness of ink mainly depends on pigment. The light fastness of the ink has no effect on the printing process, which is mainly related to the use process of the printed matter
Heat resistance:
Heat resistance refers to the ability of ink to remain unchanged when heated. The strong heat resistance indicates that the ink will not change color when the printed matter is heated to a higher temperature. The heat resistance of ink mainly depends on the types and properties of pigments and binders. Some pigments not only change color, but also change when heated
Chemistry:

This performance refers to the ability of the ink to keep its color and performance unchanged under the action of acid, alkali, water, alcohol or other solvents, also known as the chemical resistance or resistance of the ink. The ink has strong chemical resistance. Under the action of acid, alkali and other substances, the color and the nature of the ink will not change. The chemical resistance of ink is determined by the types and properties of pigments and binders, and is related to the combination state of pigments and binders, and the stability of ink

Classification:
Modern inks are mainly divided into four categories according to the type
Letterpress printing ink: a kind of printing ink used to print books, newspapers, picture albums, receipts, account books, etc. by letterpress printing. The main feature of relief printing is that the inked part of the printing plate protrudes from the non inked part. The letterpress printing ink is divided into lead printing ink, copperplate printing ink, letterpress rotary printing ink and flexible letterpress printing ink according to the type of printing machine and the use of printing products
Lithographic ink: a kind of ink suitable for lithographic printing. In offset printing, all parts of the page are basically on the same plane. The image is lipophilic and the non image is hydrophilic. The principle of oil-water repulsion is used for printing, so the offset ink must have water resistance. According to the process, it can be divided into offset printing ink, web offset printing ink, flat offset printing ink, waterless offset printing ink, iron printing ink, lithographic ink and collotype ink.
Gravure printing ink: A kind of printing ink suitable for gravure printing. When printing, the ink is inserted into the graphic part of the page, and the ink in the non graphic part is wiped or scraped off before printing. There are engraving gravure ink and photographic gravure ink
Screen printing ink: A kind of printing ink that is missed through the screen of the printing plate to the substrate surface for printing. Mesh printing ink is divided into transcription ink and screen ink.
solvent
The ink has different properties according to the different binders used. There are mainly resin based ink, solvent based ink, water-based ink and UV curing ink. The use of organic solvents as ink binders will have a negative impact on the environment. In order to make the ink meet the environmental requirements, environmental friendly materials should be used as the ink binder. Environmental friendly inks mainly include water-based ink, UV ink, water-based UV ink and some alcohol soluble inks
Waterborne ink: The biggest difference between water-based ink and solvent based ink is that the solvent used is water instead of organic solvent, which significantly reduces VOC emissions, prevents air pollution, does not affect human health, is not easy to burn, has stable ink property, bright colors, does not corrode the plate, is simple to operate, cheap, has good adhesion after printing, strong water resistance, and fast drying, so it is particularly suitable for packaging and printing products such as food, drink, and medicine, It is the world recognized environment-friendly printing material, and the only ink approved by the American Food and Drug Association among all printing inks
UV curable ink: UV curable (UV) ink refers to the ink that uses UV light of different wavelengths and energies to make the ink film and dry under UV irradiation. Using different UV spectra, different energies can be generated to polymerize monomers in different ink binders into polymers, so the color film of UV ink has good mechanical and chemical properties. The main advantages of UV ink are: (1) no solvent; (2) Fast drying speed and low energy consumption; (3) Good luster and bright color; (4) Water resistance, solvent resistance, good wear resistance. Photoinitiator in UV ink is a kind of compound that is easily excited by light. After absorbing light, it is excited into free radicals, and energy is transferred to photosensitive molecules or photocrosslinking agents, so that UV ink can undergo photocuring reaction. UV ink has become a more mature ink technology, and its pollutant emission is almost zero. In addition to being solvent free, UV ink also has the advantages of not easy to paste, clear dot, bright and bright ink, excellent chemical resistance, low consumption, etc
Water based UV ink: Water based UV ink is a new research direction in the field of UV ink. The viscosity of prepolymer in ordinary UV ink is generally very high, and it needs to be diluted with active diluent. The thinner acrylic compounds used have different degrees of skin irritation and toxicity. Therefore, while developing low viscosity prepolymers and low toxicity active diluents, another development direction is to study water-based UV ink, that is, water and ethanol are used as diluents. Waterborne UV ink has been successfully developed and applied in some printing
Alcohol soluble ink: alcohol soluble ink, which mainly plays a role in flexographic printing, is also a kind of ink with little environmental pollution, and is mainly used in food, medicine, beverage, tobacco, alcohol, packaging and printing of daily necessities in contact with human body, etc
colour
Standard color ink: Printing ink is generally the same type of standard color ink produced by each ink factory. In addition to color, the main difference of ink tone is the different luster of the ink film. There are shiny and matte types, and the semi bright ink is between the two
Spot color ink: spot color ink is a special color ink prepared by using existing color ink and auxiliary agent according to the color standard of the original design. Color continuous tone image originals are overprinted with yellow, magenta, cyan, and black four color dot printing plates, without the need for spot color ink. However, in packaging, advertising, book covers and other color printed materials, most of the colors used are spot color and flat on the spot