Printing process of sublimation printing
Transfer printing is divided into wet, dry, steam, vacuum and thermal methods. The transfer printing method can accurately reproduce the pattern, easy to mechanized production, and the process is simple, especially after the printing process is simpler than the traditional printing and printing, the printing hand feel and the printing and dyeing are the same, so it has the potential to replace the old method gradually. But most printing and dyeing factories in China still use traditional printing and dyeing methods. Only a few production units use transfer printing to produce.
At present, widely used hot-melt resins include polyamide, vinyl acetate copolymer, polyurethane and so on. The main component of polyester hot melt adhesive is polyester resin, polyester resin is polybasic acid. It is greasing with polyols. Polyamido hot melt adhesive has strong adhesion, toughness, low temperature resistance and nylon fabric affinity. It is suitable for the preparation of nylon transfer printing paper. Ethylene vinyl acetate copolymer has low melting point and strong adhesion. After printing ink, it is suitable for producing transfer printing paper. Polyurethane hot melt adhesive is mainly used for leather and polyvinyl chloride plastic bonding. Because the transfer printing is different from the printed fabrics, it is better to use the suitable hot melt adhesive ink.
1. Characteristics of transfer printing
(1) transfer printing pattern has the characteristics of realistic flower pattern, detailed pattern, clear level and strong sense of three-dimensional. Transfer printing can print natural scenery and artistic patterns.
(2) transfer printing equipment has the characteristics of simple structure, small footprint, less investment and high economic efficiency. Because the equipment is tension-free, it is suitable for printing all kinds of thick and thin sheets. In addition, after transfer printing, the factory can be packed without postprocessing.
(3) there is no environmental pollution problem in transfer printing. Due to the dry processing, without washing, steaming and drying, so there is no waste gas and waste water discharge.
(4) transfer printing has the advantages of high production efficiency, labor saving and simple operation.
Two. Mechanism of transfer printing
Transfer printing is mostly used for polyester fabric. It is through high temperature (about 200 degrees C) to make the dye to be heated and sublimated to the surface of the polyester fiber, then penetrated into the amorphous region of the fiber macromolecules, and after cooling, the printing method is fixed in the fiber.
Three. Requirements for dye printing by transfer printing
The disperse dye used in transfer printing should be lower than the melting point of fiber large molecules and the principle of non damage to the strength of fabric. The suitable processing temperature for polyester fiber is 180--210 C. In this temperature range, the molecular weight of dye upgrading is between 230--270. There are three kinds of disperse dyes in this range.
Fast dyed disperse dyes: when the temperature is about 180 degrees, the color can be sublimed, the temperature will rise again, the color will change, and the edge will be seeping.
Good disperse dyes: the temperature can rise to color within the range of 180--210 C. The hair color curve is flat. The influence of temperature on dyeing is not significant. It is a suitable disperse dye for transfer printing.
Late disperse disperse dyes: dye can not sublime and color well at 180--210 C. If the temperature is raised, a good hair color can be obtained. Such dyes are strongly dependent on temperature when they are dyed.