Application of laser particle size analyzer in water-based ink industry

    1. Water-based ink

    Water-based ink Water-based ink is referred to as Yanhuang ink. Flexographic 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 ink is especially suitable for packaging and printing products with strict hygienic conditions such as tobacco, wine, food, beverages, medicines, and children's toys.

   Water-based ink is a uniform slurry composed of binders, pigments, additives and other substances. The binder provides the necessary transfer properties of the ink, and the pigment gives the ink its color. Water-based ink binders are mainly divided into two types: water-diluted and water-dispersed. There are many types of resins that can be used in the former, such as maleic acid resin, shellac, maleic acid resin modified shellac, urethane, water-soluble acrylic resin and water-based amino resin. The water-dispersed binder is obtained by polymerizing emulsified monomers in water. It is a two-phase system, in which the oil phase is dispersed in  the water phase in the form of particles. Although it cannot be dissolved by water, it can be diluted by water, so it is also It can be considered an oil-in-water emulsion type.

     2. Development status of water-based ink

As early as the 1960s, China began to research, develop and apply water-based inks. China's annual water-based ink production is more than 100,000 tons, mainly using flexo printing. By 2010, flexo printing's share in the printing field only reached about 20%. Due to various circumstances, water-based inks cannot completely replace solvent-based inks. However, the development of water-based inks is increasing by no less than 10-30% every year, so there is still a lot of room for development in the water-based ink market in our country.

3. The importance of particle size detection of ink

     As the requirements for printing quality continue to increase, higher requirements are also put forward for inks. Today, with the rapid development of science and technology, various inks continue to appear and are used in general printing, special printing, anti-counterfeiting printing and other fields. They not only require printing The quality is excellent, and it also meets various special needs such as environmental protection, anti-counterfeiting, etc. Therefore, there are products such as magnetic ink, fluorescent ink, photochromic ink, thermochromic ink and so on. Taking the development of printing industry to a new level.

The particle size of the ink affects the wetting of the ink layer and thus the leveling and brightness of the paint. The smoothness of the paper is high, the surface layer of the paper is in good contact with the paint, and the paint is easy to level, thus forming a highly smooth film surface. The particle size of the ink affects the wetting effect of the oil layer, thereby affecting the leveling and brightness of the paint. If the ink particles are large, the printing surface will be rough and difficult to wet and level.

The fineness and purity of ink have a great impact on the quality of printed matter. To print high-quality products, you must have ink with fineness and purity to ensure it. The fineness of the ink refers to the size of the pigment (including filler) particles in the ink and the uniformity of the distribution of the pigment and filler in the connecting material. It reflects the quality of the printed product and also affects the printing durability of the printing plate. Process practice shows that if color printing products are screen-printed or solid layouts contain small negative characters and negative lines, paste, layout contamination, and quality failures may easily occur during the printing process. If there is no careful detection and analysis, the operation may become boring and the ink may be thought to be defective. The consistency is inappropriate, the viscosity is too high, the amount of cloth grinding is too large, and the pressure is too high and some wrong adjustments are made blindly. Who knew it was caused by poor ink fineness. The fineness of the ink is directly related to the properties of the pigment and filler and the size of the particles. Generally speaking, inorganic pigments are used.

(excluding carbon black), the particles are relatively coarse. This has a lot to do with the rolling process of the ink. The more times the ink is ground during the rolling process, the more uniform it will be, the larger the contact surface between the pigment particles and the binder will be, the finer the ink particles will be, and the better and more stable the printing performance will be.

4. Application of laser particle size analyzer in ink particle size detection

        At present, the method used by Chinese companies to detect the fineness of ink is mainly the scraper fineness meter method. With the development of science and technology, laser particle size analyzer detection of ink particle size has become a development trend. However, when measuring the particle size of ink with a laser particle size analyzer, the test concentration of water-based ink cannot be too high because black color easily absorbs light. Water-based ink disperses well and does not need to be ultrasonic for too long during testing.