Digital printing is the main development direction of modern printing technology. Inkjet digital printing is widely used for printing, high speed, high quality, low price and color tolerance.

　　Inkjet printing inks can be divided into dye type and pigment printing ink according to the different color agents.

　　1) dye ink.

　　Dyestuff ink is a completely dissolved homogeneous solution composed of water-based ink, resin or auxiliary agent. Is not easy to plug nozzle, easily absorbed, print color range is big, bright lustre, low price advantages, but its waterproof performance is poorer, rubbing, optical density is low, because of the relatively poor chemical stability, resistance to light also is bad, and easy to spread and dye. Generally print pictures, make color spray CARDS and other use of dye - based ink.

　　2) pigment ink.

　　Pigment printing ink is to grind solid pigments into very fine particles, dispersed in special solvents, is a suspension solution or semi-solution. The emergence of the printing ink to solve the shortcoming of the dye ink, its water resistance is strong, light fastness is strong, not easy fade, quick drying, due to pigment inks of medium penetration is weak, will not spread like dye inks, so is not easy to spread and dye. Pigment ink with its many advantages will be ink - ink development of the inevitable trend.

　　Pigment ink can be divided into water-based inkjet ink, solvent - based inkjet ink and UV ink.

　　1) water-based ink jet ink.

　　Water-based inkjet ink does not contain volatile organic solvents. It is not flammable and pollution-free. But due to the nature of water, water-based ink in substrate on the drying time is relatively long, but it in the shower nozzle and inkjet printing ink can be divided by different color agent dyestuff and pigment ink. Type dye inks are water-based ink is given priority to, because the dye dissolved in the carrier, each dye molecules is surrounded by a carrier molecule, less than particulate matter under a microscope, so it is a kind of uniformity of completely dissolved solution. Dyestuff water-based ink is not easy to block the nozzle, it is easy to be absorbed by the substrate after painting, and because the dye can express the tendency of rapid drying, it is necessary to maintain the sprinkler head regularly. In addition, water-based ink on substrate the demand is higher, apply to the permeability of porous substrate, in order to obtain the best printing effect and persistence in the outdoor, require the use of expensive special substrate, or the need for laminating process. Although the cost of water-based ink is high, it is still dominant in the home and office printers because of its low cost of application equipment. In addition, it has very successful application in digital textile printing, indoor image, direct mail, decoration and product identification.

　　2) solvent based ink.

　　Solvent - based ink refers to the ink system formed by dispersing pigment in the carrier by using organic solvent or solvent - based polymer as the carrier. Relative to water-based ink, solvent ink with bright colours, good color reducibility, less lateral diffusion on substrates, fast drying characteristics, therefore, do not need special treatment substrates, such as paper, plastic film, adhesive film and fabric printed directly without coating material. If use high quality paint, solvent ink has good anti-uv properties in outdoor applications, without having to use sticker, at the same time, the ink of volatile features can also make the ink film after drying. However, it is necessary to pay attention to the daily maintenance of sprinkler head and some problems such as solvent volatilization. It must be used in the environment with better ventilation condition. As image persistently high printing quality and the raw material cost is low, solvent ink on the large and wide in application has tremendous growth, but because of its solvent evaporation can cause environmental pollution, of ink on the market in the United States and Europe, the growth trend is limited, only to strengthen the use of the hazardous substances or environmentally friendly solvent to make the application of solvent-based inks for greater growth. However, in China's ink market, solvent - based inkjet ink is still booming.

　　3)UV ink jet ink.

　　UV inkjet printing ink with its energy saving, environmental protection, high efficiency and other advantages has become the most concerned new ink, and has a huge development prospect. It is a kind of reactive ink, under uv irradiation, a few seconds or even one second can dry curing, for the vast majority of substrate adhesion is good, and good tolerance of the chemical and physical environment. Relative to solvent-based inks, UV ink does not exist the problem of solvent evaporation, all resin, monomer into the crosslinking curing in the network, and because it is the immediate cure, performance can be immediately after printing, easy to control, but in the process of solidification, will produce ozone, so there are environmental problems. In addition, in order to meet the need of inkjet printing, it has high performance requirements for viscosity, pigment dispersion and surface tension. UV inkjet ink in the inkjet market rapid development, widely used.

　　In addition, water-based UV inkjet ink is also in development, its viscosity is lower than ink, can provide lower ink film weight. But it is higher, to the requirement of substrates during printing, water should be absorbed by substrates, if substrates to water penetration, so water should get dry during curing, for not porous substrates, should control its wettability is difficult, so it can adhesion on the surface of the special, suitable for porous permeable and porous permeable bottom half base on application, can achieve good curing effect.

　　Up to now, the sales of inkjet ink has been dominated by the long-term solvent based ink, but the market share of UV ink ink has been increasing year by year, and is on the rise. It is an inevitable trend to consider the rapid development of UV inkjet ink from the perspective of environmental protection.