The structure and composition of the ink require many considerations, such as fillers, thinners, anti-skinning agents, anti-offset agents, slip agents, and other additives. As far as the filler is concerned: it is an auxiliary agent that adjusts the ink concentration, it can also increase the thickness of the ink film layer and improve its wear resistance. It has no tinting power and hiding power. Mainly include barium sulfate, talc powder, calcium carbonate, aluminum hydroxide, etc., which are crushed into white powder when used.
Ink composition:
1.Pigments, solid components in inks, colored, black or white high-dispersion powder substances that are insoluble in water and organic solvents, are the color-developing substances of inks, and it can be divided into two categories: organic pigments and inorganic pigments. The saturation, tinting strength, transparency and other properties of the ink color are closely related to the properties of the pigment.
2.The connecting material, the liquid component of the ink, and the connecting material can be made of various materials, such as dry vegetable oil, mineral oil, solvent and water, and various synthetic resins. The fluidity, viscosity, neutral acid value, color density, water resistance and printed matter performance of the ink during usage processing are all depended on the binder.
3.Filler, a white transparent, translucent or opaque powdery substance, plays the role of filling. Appropriate use of some fillers in the pigment can not only reduce the amount of pigment to reduce costs, but also adjust the thinness and fluidity of the ink, and also improve the flexibility of the ink formulation design.
Additional materials, some materials added in order to improve the performance of the ink itself in ink manufacturing or printing usage process. When the ink composed of the basic formula still can not meet the requirements of use in some aspects, or can not meet the requirements of printing usage process due to changes in conditions, a small amount of additional materials must be added to solve the problem.
Water-based ink and flexible graphic water-based ink is also called liquid ink. It is mainly made of water-soluble resin, organic pigments, solvents and related additives through compound grinding. Water-based inks are especially suitable for packaging and printing products that require strict sanitary conditions such as tobacco, alcohol, food, beverages, medicines, and children’s toys.
1.The basic formula of water-based ink:
Water-soluble acrylic resin 25% ～ 35%;
Water 15% ～ 25%;
Ethanol 5% ～ 15%;
Triethylamine 5% ～ 10%;
Pigment 10% ～ 30%;
Additives 1% ～ 3%.
2.Water-based ink components: water-based inks are composed of water-based polymer emulsions, pigments, surfactants, water and other additives.
(1) Water-based polymer emulsion
It is mainly acrylic and ethyl styrene compounds. The role is to transfer the pigment carrier, providing adhesion, hardness, brightness, drying speed, abrasion resistance, water resistance. Film-forming emulsions are used for printing on the surface of non-absorbent substrates; non-film-forming emulsions are used for printing on absorbent materials such as paper and cardboard.
(2) Pigment
Organic pigments include phthalocyanine blue and Lithol red; inorganic pigments include carbon black and titanium dioxide.
(3) Surfactant
The function of surfactant is to reduce the surface tension, make the ink spread on the substrate, and improve the stability of the ink.
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, etc. The liquid component in the ink component is called the binder; the solid component is the colorant (pigment or dye) and various additives.
For inks, color, body bone (the rheological properties of ink such as thinness, fluidity, etc are usually called ink body bone) and drying performance are the three most important properties of ink, which are also the development of ink formulation, technology and production, attention should be paid; the printing film on the printed product should have a certain resistance to make the printed product have practical use. Mastering the deployment of spot color inks, controlling the amount of inks, and making full use of the remaining ink will not only save materials, but also improve personal quality and technical level.
The physical and chemical properties of ink mainly refer to its density, fineness, transparency, gloss, light resistance, heat resistance, and acid, alkali, water, and solvent (alcohol) resistance.
In terms of density: Density refers to the weight of ink per unit volume at 20°C. Expressed in g/cm. The density of the ink is determined by the type and ratio of the raw materials used in the ink, and is affected by the external temperature. The density of the ink has a certain relationship with the printing process. The density of the ink is related to the amount of ink used in the printing process. Under the same printing conditions, the amount of ink with higher density is greater than that of ink with lower density.
The density of the ink is too high, mainly due to the high density of the pigment in the ink. In the printing process, because the binder can not drive the pigment particles with too high density to transfer together, the solid particles such as the pigment are accumulated on the surface of the ink roller, printing plate, or blanket, forming a blockage phenomenon. Especially in high-speed printing or ink thinning, the use of high-density ink is more prone to this phenomenon. At the same time, when the high-density ink is mixed with the low-density ink, if the difference between the two is too large, the ink color delamination is likely to occur. The ink with low density floats up and the ink with high density sinks, so that the color of the ink surface is biased toward the ink with a lower density, and the color of the bottom ink is biased toward the ink with a higher density.
Generally, the density of printing ink is between 1g/cm and 2.25g/cm.
- The blending of inks is based on the principle that the three primary colors of Y, M, and C can be mixed into black in a certain proportion.
- The three primary color inks Y, M, C can be mixed in equal proportions to mix black, and add different proportions of diluent to get different degrees of neutral gray.
- Three primary color inks Y, M, and C can be mixed in different proportions to obtain different colors or multiple colors. The primary colors of Y, M, and C three primary colors are R, G, B, and Y, M, and C are multiple colors. One thing to note is that the mixed hue is biased to the hue of the ink with a large proportion.
- The two primary colors of ink are mixed in equal amounts to obtain the standard intermediate color.