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. 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: 

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, 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

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, 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, 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. 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; Furthermore, corrugated box is a loose fabric with strong water absorption. Application of Water-Based Ink in Corrugated Paper Printing

     After printing water-based ink, it is mainly permeable drying without setting a drying device; 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. 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, 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. 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