1. Common printing methods and inks of corrugated paper   Application Of Water-Based Ink In Corrugated Paper Printing

       Because the corrugated board is composed of multi-layer wavy corrugated, the surface flatness is poor, and the printing pressure can not be too large.Application Of Water-Based Ink In Corrugated Paper Printing

        The screen printing method can only print some simple patterns and words, which is difficult to print, so the corrugated board is generally printed with flexographic printing. Application Of Water-Based Ink In Corrugated Paper Printing

        This is mainly because: Application Of Water-Based Ink In Corrugated Paper PrintingApplication Of Water-Based Ink In Corrugated Paper Printing

① the elastic deformation of flexo can make up for the thickness error and uneven surface of corrugated paper in the printing process, so as to make the printing ink color uniform, so as to improve the quality of finished products; Application Of Water-Based Ink In Corrugated Paper Printing

② Flexographic printing pressure is small, even after the compression deformation of the printing plate, it can better contact with the corrugated board with uneven thickness, Application Of Water-Based Ink In Corrugated Paper Printing

      so as to avoid the phenomenon of thick part of the imprint paste, poor contact of thin part, empty and false imprint;Application Of Water-Based Ink In Corrugated Paper Printing   Application Of Water-Based Ink In Corrugated Paper Printing

③ Flexographic printing adopts anilox roller to transfer ink, which is convenient for the transmission of water-based ink. The printing plate only needs to touch the corrugated paper gently, Application Of Water-Based Ink In Corrugated Paper Printing

      and the water-based ink will be absorbed by the corrugated paper;Application Of Water-Based Ink In Corrugated Paper Printing

 ④ The flexographic printing machine has simple structure and is easy to be combined with other processes, such as indentation, slotting, die cutting, gluing, box making and other corresponding machines for on-line operation.Application Of Water-Based Ink In Corrugated Paper Printing

      When using flexographic printing corrugated paper, the commonly used inks mainly include solvent ink, water-based ink and UV ink. With people’s attention to environmental protection factors, Application Of Water-Based Ink In Corrugated Paper Printing

       the proportion of solvent ink is decreasing year by year, while water-based ink and UV ink are becoming more and more popular. Application Of Water-Based Ink In Corrugated Paper Printing

       At present, water-based inks grow fastest and account for a large market share. For example, about 90% of flexographic inks in the United States are water-based. Application Of Water-Based Ink In Corrugated Paper Printing

        In the flexible printing of corrugated box, water-based ink accounts for a larger proportion, because the text or simple pattern printed on corrugated box does not need high gloss, and water-based ink can meet the requirements of print quality; Application Of Water-Based Ink In Corrugated Paper Printing

      Furthermore, corrugated box is a loose fabric with strong water absorption. After printing water-based ink, it is mainly permeable drying without setting a drying device; Application Of Water-Based Ink In Corrugated Paper Printing

      And the water-based ink is non-toxic, harmless, non flammable, easy to use, safe and low cost. Therefore, combined with these factors, the main printing method of corrugated paper is flexo printing, and the most commonly used ink is water-based ink.Application Of Water-Based Ink In Corrugated Paper Printing

2. Water based ink in corrugated paper printing

2.1 composition of water-based ink

(1) Connecting material

      The linking material in water-based ink is water-soluble resin and waterborne polymer emulsion. There are many kinds of waterborne resins, such as rosin maleic acid resin, styrene maleic acid resin, acrylic acid copolymer, ethyl acrylate and so on.Application Of Water-Based Ink In Corrugated Paper Printing

      Polymer emulsion, waterborne dispersing resin, has vinyl acetate copolymer, acrylic acid copolymer, polyurethane resin, epoxy resin and so on. Application Of Water-Based Ink In Corrugated Paper Printing

      At present, water-based acrylic resin is the most commonly used binder in water-based screen printing ink. The most successful acrylic polymers currently used are mainly four kinds of alkali soluble resin, acrylic emulsion, colloidal emulsion and solution, and special acrylic polymers.Application Of Water-Based Ink In Corrugated Paper Printing

(2) Paint

        Water based inks mainly use organic or inorganic pigments with strong alkali resistance and good dispersion in water system. In addition to ordinary powder pigments, these pigments also include pigment filter cake,Application Of Water-Based Ink In Corrugated Paper Printing

        pigment aqueous dispersion and easily dispersed pigments in water. The pigment in water-based ink must have strong alkali resistance, high hiding power, high color concentration and easy dispersion.Application Of Water-Based Ink In Corrugated Paper Printing

(3) Cosolvent

       Due to the small solubility and wettability of water, corresponding cosolvent shall be selected, such as ethanol, propanol (n, ISO), ethylene glycol monoacetic acid, etc.Application Of Water-Based Ink In Corrugated Paper Printing

       Adding cosolvent can improve the shortcomings and stability of ink, reduce the surface tension of water-based ink, increase the wetting of plastic, dissolve resin and improve the drying speed.Application Of Water-Based Ink In Corrugated Paper Printing

      In addition, the resin is generally insoluble in water, and appropriate alkaline substances must be added to promote the resin to dissolve in water. Generally, amines such as ethanolamine are selected, and the dosage depends on the pH value.Application Of Water-Based Ink In Corrugated Paper Printing

(4) Auxiliaries

There are many kinds of additives, such as diluent, dispersant, brightener, defoamer, diluent, electrostatic agent, etc., to improve the printability of ink.

2.2 requirements for water-based ink used in corrugated paper printing

        The biggest feature of corrugated box is that the paper is rough, the surface is not flat enough, the ink penetration is fast, and most of the face paper is dark yellowish brown. Application Of Water-Based Ink In Corrugated Paper Printing

       In order to produce the printing effect of full ink layer, rich layers and bright colors unique to flexographic printing, high-quality water-based ink should be used.Application Of Water-Based Ink In Corrugated Paper Printing

        In addition to the requirements of ordinary water-based ink, the following points should be considered when preparing water-based ink for corrugated paper printing.

(1) The basic color should be bright and strong, so as to ensure that the imprint has high hiding power; At the same time, it can achieve the basic balance of low viscosity and high color concentration, so that the hierarchical plate and dot printing can be clear and distinct.Application Of Water-Based Ink In Corrugated Paper Printing

(2) It is necessary to maintain fast penetration drying performance, adapt to high-speed printing, avoid back rubbing dirty, and have good leveling performance to make the imprint flat, Application Of Water-Based Ink In Corrugated Paper Printing

       bright and clean, show full and bright color effect, and let the printing factory have the conditions to select a wide range of paper and paperboard.Application Of Water-Based Ink In Corrugated Paper Printing

(3) The printing process must have good re solubility to ensure the smooth ink development process and adapt to various printing speeds.Application Of Water-Based Ink In Corrugated Paper Printing

(4) Imprinting has good wear resistance and water resistance, which can meet the new performance requirements of packaging materials.Application Of Water-Based Ink In Corrugated Paper Printing

3. Some problems of using water-based ink in corrugated paper printing

(1) Flexographic printing uses anilox roller to transfer ink. The mesh hole is small. A filter screen should be added in the water-based ink barrel to prevent impurities from damaging the anilox roller.Application Of Water-Based Ink In Corrugated Paper Printing

(2) The water-based ink should be fine in texture, bright in color, and the viscosity of the ink should match the printing speed.Application Of Water-Based Ink In Corrugated Paper Printing

(3) The water-based ink selected for corrugated paper printing is an oil-water miscible system formed by resin and water under the action of surfactant. Application Of Water-Based Ink In Corrugated Paper Printing

      The stability of this system is poor. The stability of water-based ink depends on its pH value. Application Of Water-Based Ink In Corrugated Paper Printing

      When the pH value drops to about 7.8 or lower, the ink begins to be turbid, thickened and easy to form a film, which hinders the normal transmission of the ink.Application Of Water-Based Ink In Corrugated Paper Printing

      The alkalinity is too strong, which affects the anilox roll. Generally, the pH value is controlled at 8-9. Water based ink is alkaline, similar to soap solution, easy to bubble.Application Of Water-Based Ink In Corrugated Paper Printing

(4) Fully stir before use to keep the ink composition uniform; After opening and using, the ink storage shall be covered and sealed immediately to prevent dust falling and crust drying; Application Of Water-Based Ink In Corrugated Paper Printing

      If the remaining ink contains impurities, it should be filtered first and then used together with new ink; Please avoid exposure to high temperature or hot sun during storage. Application Of Water-Based Ink In Corrugated Paper Printing

       It will not deteriorate under normal conditions for one year.Application Of Water-Based Ink In Corrugated Paper Printing

(5) Rational use of ink additives. There are many types of additives for water-based ink, which should be used correctly according to the instructions. Application Of Water-Based Ink In Corrugated Paper Printing

       Before formal printing, we should comprehensively consider many factors such as printing conditions, surface characteristics of substrate, ambient temperature and humidity, storage time of water-based ink and so on.Application Of Water-Based Ink In Corrugated Paper Printing

      At present, in corrugated board printing, water-based ink has occupied a dominant position, its printing quality has been recognized by people, and its pollution is small, so it is used more and more. Application Of Water-Based Ink In Corrugated Paper Printing

      At present, there are still some problems to be solved, especially the problem of drying speed. However, with the development of ink technology, the development prospect of water-based ink is still bright.Application Of Water-Based Ink In Corrugated Paper Printing