Research Progress of Waterborne Ink Materials (1)

Abstract: Firstly, the classification and characteristics of water-based ink binders were introduced. Then the research progress of water-based ink binders, ie the research status of modified pine perfume resins, modified acrylic waterborne resins and emulsion-based binders, was discussed and discussed. The status of the application of water-based ink binders, and finally its prospects for development.

Keywords: water-based ink; water-based binder; rosin resin; acrylic resin

Water-based inks are abbreviated as water-based inks and are composed of water-soluble or water-dispersible high-molecular resins as linking materials, organic pigments, solvent water and related auxiliary agents. The main difference between water-based inks and oil-based inks is that solvent-based inks use organic solvents as the solvent, while water-based inks use water (45%-50%) as the solvent. Therefore, water-based inks have the advantages of extremely low VOC content, low toxicity, and non-flammability. Being more favored, as a "green printing" material in the flexible packaging and food packaging printing industry, the rapid development. The binder plays an important role in water-based inks. It is the base material of the ground toner in ink manufacturing, the main mobile phase, and the film-forming substance after the ink is dried, directly determining the performance and printing effect of the ink. Such as viscosity, adhesion, gloss and dryness. The technological innovation of the linking material determines the technical innovation of the ink. In the continuous development of the water-based ink, the performance has been continuously improved, and has developed into an ink type in which the versatility and printability are continuously improved.

The earliest water-based ink was a natural resin shellac dissolved in ethanol and an alkaline aqueous solution as the connecting material. With the development of synthetic technology, rosin and maleic acid modified resins gradually replaced casein, shellac and other natural substances. Resin, as a binder for water-based inks. This type of modified resin greatly improves the printability of water-based inks. The application extends to the flexo printing of kraft paper and corrugated paper, but it still has a higher gloss, water resistance and stability. Many problems, this is the first generation of water-based inks.

The second-generation water-based inks are based on a solution of styrene-acrylic acid copolymer resin. The water-based inks developed at this time have a significant improvement in storage stability and water resistance, but they have a high level of gloss and printability. There is still a gap between solvent inks. On the basis of the second-generation water-based inks, ink developers introduced the polymerization of acrylic monomers and styrene to develop a polymer emulsion resin with a core-shell structure and a network structure, which greatly improved the gloss of inks. Degree of drying and broaden the application of water-based inks.

This article mainly reviews the classification and characteristics of aqueous binders, their research progress and application status, and at the same time, their application prospects are prospected.

1 Classification and characteristics of water-based ink binders

Water-based binders are also called water-based resins. Compared with solvent-based resins, water-based resins are characterized by low toxicity, non-flammability, no organic solvents, and no pollution. They are called 21st century green resins. Water-based resin is a kind of polymer material containing hydrophilic groups. When water is used as a solvent, it can be dissolved or swelled to form a solution or a colloidal emulsion. Therefore, they are generally classified into three types according to their different formation states in water: water-soluble resins, hydrosol resins, and water-dispersible resins.

The water-soluble binder resin can be permanently dissolved in water to form a solution state. The formulated ink cannot be used in a water-contacting environment and is limited in use and cannot meet the printing needs. The water-soluble resin is generally not used as the main raw material of the water-based ink, and its use is mainly to adjust the viscosity and fluidity of the ink, stabilize the dispersion effect, give the pigment dispersion effect and the ink ink film shape and the pigment fixation and other properties.

The hydrosol-type resin has one or more hydrophilic groups in its molecular structure and can form organic salts, which have good solubility with water and are therefore called water-reducible linking materials. Since the current modification in the hydrophilic group is mainly accomplished using low molecular weight amines, it is also referred to as an alkali soluble resin, ie, an alkaline solution of an acidic resin, which can be dissolved by a solution of water or an amine and water. Resin has the advantages of fast film formation after printing and drying. Glue, maleic resin, urethane resin, water-based amino resin, water-soluble acrylic resin, etc. are used for this kind of resin.

A water-dispersible binder is a fine-particle resin suspended in water, also called a latex, so this type of binder is also called an emulsion binder. The emulsion-linking material has fast water dilutability, fast drying speed, and good water resistance of the ink film. The formed latex can have a high solid content and a low viscosity, and can produce a high-quality thin film coating. However, the latex ink is difficult to print and has poor re-dissolving properties (the latex becomes insoluble after coagulation) and is difficult to clean.

The disadvantage of water-based binders is that with the prolonged storage time, poor water-solubility and reduced gloss will occur. In order to better reflect the performance of the three types of binders, Table 1 lists the different performance parameters of the three binders.

2 Research progress of water-based binders

With the development of modern polymer theory, the relationship between the structure and properties of polymer surfactants has become more and more clear. In theory, almost all resins that can be used in traditional oil-based inks, such as polyesters, phenolics, urea-formaldehydes, alkyd, epoxy, polyamides, and polyurethanes, can be made into water-soluble resins by intermolecular graft copolymerization. Of course, to achieve this goal, on the one hand, superb synthesis technology is required. On the other hand, there is a clear understanding of the relationship between pigments and resins in inks and the relationship between resins and substrate materials. At present, there are water-based alkyd resins, amino resins, phenol resins, epoxy resins, acrylic resins, and the like for use in the film forming of aqueous inks. At present, most of the water-based inks used are rosin, polyacrylic, and modified acrylic emulsions.