Fabric printing mainly uses two types of inks - plastic inks and water-based inks. Plastic ink is based on PVC (polyvinyl chloride). Basically free of solvent, it is also known as 100% solid ink system with UV ink. Water-based inks are classified into dye-based and pigment-type inks, and they cure at room temperature or in a specific drying device (convection oven or infrared radiation device) with the release of moisture and other volatile organic compounds. Plastic inks and water-based inks have their own technical advantages and defects in specific applications, and their impact on the environment is not the same. Should be considered comprehensively and reasonably selected. Plastic inks are often used in finished fabric printing such as T-shirt jackets, handbags and the like, while water-based inks are often used in fabric printing.
Plastic ink system
The main components of plastic ink are plasticizers and PVC. When the plastic ink is heated to a certain temperature, the PVC particles swell and absorb the liquid plasticizer cross-linking reaction to form a solid elastic film. The curing temperature is generally 149 to 166. C plastic ink is user-friendly ink, easy to manage. Suitable for a variety of fabric printing, easy to fix, resistant to washing, as long as the fabric to adapt to curing temperature. Can absorb ink to use. Since plastic inks do not contain solvents and do not naturally cure, based on this feature, plastic inks are less likely to block the web and are suitable for wet-on-wet printing.
Plastic inks have a variety of transparency and can be selected based on the type and color of the fabric. Its price varies with transparency, in general. The lower the transparency, the more expensive the price is because the pigment content will increase as the transparency decreases. Therefore, a reasonable choice of ink transparency, control costs.
The curing of plastic ink requires a higher temperature. Generally light-colored inks have a longer curing time than dark inks, and the thicker the film, the longer the curing time. However, if the curing time is too long, the plasticizer in the ink will enter the fabric and affect the image quality. If the curing is not complete, the PVC resin particles cannot fully absorb the plasticizer and the ink layer is easily broken and peeled off.
Plastic inks are thermoplastic and remelt when exposed to heat. Products printed with plastic ink cannot be ironed, otherwise the printed pattern will be blurred. Uncured plastic ink contains certain harmful chemicals. In order to protect the environment, the waste ink should be heated to 160. C. Make it completely cured and harmless.
Water based ink system
Textile printing inks mainly use water as solvent. However, water is not the only solvent but also more or less contains petroleum-based solvents to shorten the drying time of the ink on the fabric. Reduce the effect of heating on the fabric.
Fabric prints made with aqueous inks are soft, especially when printed on cloth. Water-based ink is suitable for large-scale printing equipment with drying device. In addition, it has strong penetration ability and is suitable for printing on thick fabrics. Such as towels. Water-based ink compared with plastic ink. Difficult to dry, requires a huge drying device, and must be maintained at a relatively high temperature for a period of time, in order to facilitate the solvent evaporation film drying. In order to increase the drying speed and facilitate the thorough drying of the ink, most aqueous inks require the addition of a catalyst. But adding the catalyst ink. Can only maintain 4-12 hours.
Application comparison
(1) Printing accuracy. The water-based ink has good fluidity and is suitable for fine screen printing. The print pattern has high definition, but the hiding power of ink is not as good as that of plastic ink. It is not suitable to print on dark fabrics.
Plastic ink has been able to print about 85 lines/inch of halftone pattern, due to the high hiding power of ink. More suitable for printing on dark fabrics.
(2) feel. Water-based ink printing ink film is thin, compared with plastic ink, soft to the touch. This is because the plastic ink is a 100% solid-state system. After curing, the ink layer is thicker, while the water-based ink has only 20% solids content. 80% of moisture and other organic solvents will be removed during the drying process. Therefore, the ink layer thickness is only 1/5 of the plastic ink layer. However, water-based inks are slightly darker in color than high-gloss plastic inks.
(3) Prices. At present, many countries and regions have introduced laws and regulations that restrict the use of ink solvents. In order to control the environmental pollution of the solvent and the harm to the workers, thus. Some inexpensive solvents will gradually be eliminated. The dramatic rise in solvent prices will increase the cost of inks. Plastic inks require large amounts of organic solvents, while water-based inks do not require organic solvents, which can reduce cost. on the other hand. Water-based ink huge drying system energy consumption. With rising energy prices, there is a need to find a more energy-intensive ink drying/curing system.
Reprinted from: China Printing and Packaging Network