3 Organic Pigment Colorants
Inkjet printing colorants fall into two categories, namely water-soluble dyes and water-insoluble organic or inorganic pigments. The main advantages of dye colorants are complete chromatograms, bright colors, high color yield, excellent water solubility, easy to make ink, low cost, easy to make high-concentration inks, good ink stability, easy to block the print head, print Good quality, suitable for fast inkjet printing, there is no ecological environmental issues. Water-based inks are generally formulated with water-soluble dyes, humectants, driers, viscosity modifiers, pH regulators, anti-mold agents, and purified water. Most commercial inks used in current inkjet printers fall into this category. However, printing products printed with water-based inks formulated with dye colorants have disadvantages such as poor water fastness and light fastness, and are easily stained [10], especially for textiles currently printed by ink jet printing. The added value is very high, and the requirement for fastness is obviously higher than that of general fabrics.
The use of pigments (paints) for inkjet printing is a topic of interest to everyone. The size of the pigment particles in the ink was found to be particularly sensitive to nozzle clogging, rheological properties and stability of ink during ink jet printing. Pigment inks are also difficult to print with darker colors due to the limitations of viscosity, which limits the research and development of it. Therefore, the DOD system printing is based on the dye-based ink is the only choice, even if used for CIJ system printing is limited to the resolution of less than 2OOdpi pattern.
The greatest advantage of pigment colorants is their excellent light fastness and water fastness. However, pigments are insoluble in water. Therefore, when formulating water-based printing inks with pigment colorants, the pigments are usually ground to a fine powder, which is dispersed and suspended in water with a surfactant or a polymer dispersant to make water-based inks. Ink and ink [11,12]. Water-based printing inks are thermodynamically unstable systems and are difficult to formulate as high-concentration inks with good stability. Due to surface tension and other reasons, pigment colorants tend to aggregate in water, therefore, the color strength of printing is low, the color is not bright, the pattern is not clear, and it is easy to block the nozzle. In addition, pigment colorants also have disadvantages such as incomplete chromatograms, insufficient color, poor transparency, and high ink costs. Therefore, practically available pigment colorants for printing inks for inkjet printing are very limited, and are a new area for research and development, and they are rarely commercialized completely. For example, Hoechst Celonese's HOSTAFINE product is an oil/water microemulsion with a solid content of 40%-50%. The stable storage period of the product is one year [4]. Another product is a water-based ink colorant recommended by German HF Company. The trade name is FLEXOTAN, and the powder content of 80%-90% of the pigment content is stirred in water to achieve a good dispersion effect. Species include yellow HFG-PVP 2087 (C.1.PY.151), yellow HR-PVP 2011 (PY83), magenta E-PVP 2088 (PR202), magenta HF4C-PVP 2040 (PR185), red HF2B-PVP 2012 (PR208), Purple RL-PVP 2089 (PV23), Blue B2G-D (PB 15; 3) [13]
Ciba's Irgaphor series of pigment inks for inkjet printing currently has eight varieties. That is, Irgaphor yellow TBI-100, Golden yellow TBI-200, Red TBI-300, Navy TBI-400, Blue TBI-500, Green TBI-600, Grey TBI-700, Black TBI-800. There are also seven types of highly concentrated formulations, namely: Irgaphor Yellow TBI-150HC, Golden Yellow TBI-250HC, Red TBI-350HC, Magenta TBI-380HC, Blue TBI-550HC, Green TBI-650HC, and Black TBI-850HC.
There are many varieties of pigment available for selection [8].
Black pigment varieties are: C.1. Pigment Black 7 and 11, the largest amount is carbon black.
Yellow pigment varieties: C.1. Pigment Yellow 1,3,12,13,14,17,23,24,34,37,42,53,55,81,83,95,97,98,100,101,104,108,109,110, 117, 120, 138, 153 and so on. Among them C.1. Pigment Yellow 14 is a relatively large variety.
Magenta pigment varieties are: C.1. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48; 2.48; 3.48; 4.49; 1.52; 2.53; 1.57; 1.60; 1.63; 1.63: 2.64; 1, 81, 83, 88, 92,101,104,105,106,108,112,114,122,123,146,149,166,168,170,172,177,178,179,185,190,193,209,219 and so on. Among them C.1. Pigment Red 122 is one of the better performance varieties.
Cyan pigment species are: C.1. Pigment blue 1, 2, 15, 15: l.15; 2.15; 3.15; 4.15; 5.15; 6.16; 17: l, 56, 60, 63, etc. More used is C.1. Pigment Blue 15; 3.
Inkjet printers rarely use only four nozzles of black, yellow, magenta, and blue. There are mainly 7-8 or even 12 nozzles. Therefore, a variety of pigments such as bright yellow, dark blue, etc., must be added.
DOD inkjet printing is performed using thermal foaming technology and micro-piezoelectric technology. The thermal foaming technique is controlled by a computer signal to heat a resistor to a certain temperature (350°C), causing the ink to produce misty bubbles, and the misty bubbles are cooled or broken to form ink droplets, which are ejected from the nozzle to form a pattern, which requires a colorant High temperature resistance. Normal dyes cannot be used, and some organic pigments with high heat stability can be used for inkjet printing of this technology. For example PR. 122, PR. 149, PY. 12, PY. 94, PY. 110, PR. 68, PV. 31 and PB. 15 3 and so on.