The basic functions of the most popular ink system

Select ink - the basic function of the ink system

selecting an ink suitable for special applications is very important for all printing processes. Professional silk printers generally use thick ink film printing process, which is different from other printing processes in the printing industry. No other printing process has such good light resistance, wear resistance and durability. As a thick ink film printing process, it has obvious advantages in printing rigid or soft products. In order to help select the ink suitable for a substrate, the basic functions of the commonly used ink system are introduced below

I. UV ink

among all the ink systems currently used, UV ink series has had a great impact on the optical media market in the past 10 years

uv inks belong to photoreactive inks compared with those solvent-based inks and evaporative drying inks. In the solvent system, once the solvent leaves the ink, it will form a dry ink film. UV chemical components contain oligomers, monomers and photoinitiators. Solvent based inks contain resins, while UV inks contain oligomers -- a completely different resin from those used in solvent evaporated coatings. Oligomers will react chemically with monomers in the chemical composition. In UV ink, monomer is the equivalent of solvent. Monomer as a carrier can provide the ink viscosity required for printing

in UV ink, the coating is 100% curable, because all substances in the coating will change from liquid to solid

the curing process is stimulated by photoinitiator. Photoinitiator is the cocatalyst of chain reaction. In this reaction, free radicals or molecules are linked to other molecules, resulting in the polymerization of the entire UV ink layer. UV ink can withstand die cutting, bending and molding, and can maintain good resistance and bending resistance, and can withstand the outdoor natural environment for at least 5 years. Compared with solvent evaporated ink, UV ink has many excellent characteristics. In printing production, a 60 foot long gas drying device has been adopted in the foot long UV reactor, which can greatly reduce the cost. At present, the printing problem of UV ink is gradually reduced, not only the viscosity of the ink will not change, but also the ink will not evaporate. Due to the perfect management of ink in production, four-color printing is easier

second, water-based UV ink

some successful printing have used water-based UV ink, and the solid content of this ink meets the requirements of printing on non coated paper. The high ratio of moisture greatly reduces the thickness of the cured ink film. This kind of ink can be diluted with water or cleaned with water

compared with ordinary UV inks with high solid content, water-based UV inks require lower UV energy

disadvantages of using water UV ink polymer fluid assisted molding technology research is difficult to deal with this lightweight paper or porous paper. Paper edge warping is a common problem. This kind of paper absorbs water quickly. The resin system needs to release water quickly without affecting the crosslinking function of the resin

III. ordinary water-based inks

water-based inks have not been greatly improved. The most commonly used are image printing plants, especially those that often use more than 80 pounds of paper. When the ink film is dry, the printed paper is rarely wrinkled or curled. Vinyl and metal substrates are used in very limited applications. Chemical film hardener is often used in production to improve its appearance performance, but considering that ink chips are easy to be caused during die cutting, it is also necessary to give consideration to the softness of the ink by sintering the mortar and clay brick into a whole

the commonly used fields of water-based inks are styrene, polyolefin, light weight paper, etc., which can be used to make products with good durability, chemical resistance and water resistance

IV. epoxy resin ink

if the epoxy resin is mixed properly, it will have excellent characteristics of resistance to various substrates, such as glass, metal, ceramics, wood, plastics and many other materials

epoxy ink is divided into two categories: one component and two component. One component ink system is made of thermosetting resin. They must be baked and cannot be air dried. The two-component system needs to add catalyst or film hardener, and has the advantage of air drying. At present, there is a baking formula of this ink system

there are several catalysts that can be added to epoxy ink to combine with almost any substrate. The two-component epoxy resin system has a much longer shelf life than the single component, and the color ink will not deteriorate quickly. "Applicable period" is a limit for the ink to remain usable. The time limit of ink viscosity on the plate is usually expressed in hours or minutes. Changing the epoxy resin with solvent will not affect or extend the service life

v. gold and silver powder ink

when considering using gold and silver powder ink for decoration, we must use gold and silver powder pigment with binder. Gold and silver powder pigment must float on the surface of the ink film and be overprinted on it during drying and curing. The process of overlapping gold and silver powders is called metal powder suspension

at present, gold and silver powder can be added to solvent-based, water-based and UV inks. Gold and silver powder can maintain its good brightness in acrylic resin and vinyl resin. Because gold and silver powder will oxidize when exposed to water, it will bring some problems to water-based ink. For UV inks, the stability of mixed inks lasts for a very short time. As we all know, the hiding power of gold silver powder inks is very good, because they are made of MM zinc, copper and other dry ground metal powders. However, the gloss darkening often occurs, which is mainly caused by improper mixing of inks. Gold and silver powder is not suitable for long-term outdoor exposure, because it will eventually lead to a decline in metal gloss. At present, there is a transparent laminated film that can protect gold and silver powder pigments. When gold and silver powder cannot maintain the required brightness and temperature, printers sometimes use pearlescent pigments instead. Unfortunately, pearlescent pigments do not have the hiding power of gold and silver powder pigments

VI. plastic, paper and metal printing inks

plastic, paper and metal printing inks constitute most of the inks used by image printing and industrial silk printing workers. If you don't use these three inks for printing at present, but you plan to use them in the future, you can take a look at the knowledge introduced below, which will help you make a choice

1. Plastic printing ink

Plastic printing ink is dried by evaporation, oxidation or polymerization, and forms a physical and chemical bond, which dissolves the plastic surface, similar to corrosion. On the other hand, oxidation and polymerization inks will be bonded into a highly adhesive called mechanical adhesion. Such inks can be used for highly solvent resistant thermoplastic substrates, such as polyethylene and polyester

varnish silk printing inks are mainly used for printing thermoplastic materials, such as acrylic acid, cellulose acetate, butyrate, nitrocellulose, polyvinyl chloride and their combinations. This kind of ink system is mainly used for vacuum formed rigid plastics, but its aging must be checked frequently, because they will lose adhesion after long-term exposure to light and heat. Some plastic films, such as acrylic acid and styrene, will have cracks on the surface when active solvents are used in varnish. Cracks may not be found until very late, sometimes until the printing is completed. When printing on acrylic or styrene materials, specially prepared inks should be used to prevent this from happening

UV drying on polyethylene can be completed in a few seconds. No UV curing ink can meet the requirements of users for selecting a wide range of plastics. Polystyrene and PVC use one ink system, while polyethylene and polypropylene use a different ink system

the functional component in the diffusion ink series is a dye that can penetrate or diffuse to some suitable substrates. These dyes can be operated by traditional silk printing methods and baked in an oven at 180 ° f for 30 minutes. Thermal diffusion melts the dye into the plastic, making it an integral part of the plastic. This ink system has four advantages: the ink does not dry on the plate; Ink can be adjusted with water or glycerin; The plate can be cleaned with water; Printed matter is resistant to fading

2. Paper printing ink

in the first transmission mode of all the above inks, advertising printing ink is the easiest to use. This ink can be printed on all kinds of coated and non coated paper. This kind of ink is used to print advertisements at the point of purchase, information advertisements, corrugated boxes, signs and greeting cards, and the decorative effect is very good. Gloss is the degree of gloss, which is usually determined by the type of ink, but if it needs to be changed to a certain degree, it is necessary to add matte media or special inking oil to the ink. If you change from high gloss to standard gloss, such as silk, eggshell and other Matt surfaces, it is best to use advertising printing ink

at present, the most representative inks are advertising ink, nitrocellulose paint and multifunctional ink. These inks should be added with diluents or blockers before printing to make them have good ink flow performance. For most ink systems, thinners in the form of thinners, blockers/fillers make advertising printing inks relatively inexpensive per gallon

standard gloss or flat tone advertising ink requires air drying for 15-20 minutes. Under the condition of air jet drying, it only takes a few seconds. Using 200-260 threads/inch of silk, the average printing area per gallon of ink is about 1500 square feet (1 square foot =0.0929 square meters) for prints with good hiding power

3. Metal printing ink

precoating metal does not require additional treatment of the material. Its surface has been treated to improve the reliability of test results and coated with a coating. Polyester coating and acrylic coating are the two most commonly used metal coatings, but the metal must be measured in advance. In order to obtain the required adhesion performance, the metal surface and ink must reach ° F

metal printing inks can be air dried, thermosetting or catalytic drying. The method of roller coating, spraying or printing can be used to coat the primer on the metal surface. After coating with this primer, the metal can withstand shearing, punching, forming and other operations. The color of the bottom layer also protects the bottom coating. The primer resin will age under UV light. Printing a transparent layer on it can protect its surface. Other coatings must be compatible to ensure the adhesion between the coatings

reprinted from: China ink information