Roller printing
This technique is used whenever long runs of fabric are to be printed with the same design. The modern machine, based on one originally devised in 1783, consists of a large central cast-iron cylinder over which passes a thick endless blanket providing a resilient support for the fabric. Backing fabrics, called back grays, are placed between the blanket and the fabric to prevent undue staining of the blanket. Although formerly made of cotton fabric, most modern back grays are continuous belts of nylon. The blanket and back gray are appropriately tensioned, so that the fabric moves through the machine as the central cylinder rotates. Engraved printing rollers, one for each colour, press against the fabric and the central cylinder. The pattern on the roller is etched on the surface of a copper shell supported on a mandrel. High-quality engraving is essential for good printing. Each printing roller is provided with a rotating colour-furnishing roller, partially immersed in a trough of printing paste. Finely ground blades (doctor blades) remove excess colour paste from the unengraved areas of these rollers, and each also has a lint blade. The printed fabric passes from the main cylinder and through a drying and steaming chamber to fix the colour. Although this machine prints only one side of the fabric, the Duplex roller machine, essentially a combination of two roller machines, prints both sides. Modern printing machines are smooth-running precision machines fitted with carefully designed roller bearings and hydraulic or pneumatic mechanisms to ensure uniform pressure and flexibility. Pressure is regulated from an instrument panel, and each roller is controlled independently. Automatic registration is effected by electromagnetic push-button control, and modern electric motors provide smooth-running, variable-speed drives. The washing of back grays and printer’s blankets has also been automated.
Spray printing is the application of colour from spray guns through stencils and has limited but occasionally profitable use.
Screen printing
Screen printing may be a hand operation or an automatic machine process. The cloth is first laid on a printing table, gummed in position or pinned to a back gray, and then the design is applied through a screen made of silk or nylon gauze stretched over a wooden or metal frame, on which the design for one colour has been reproduced. This is usually a photographic process, although hand painting with a suitably resistant blocking paint is an alternative. A screen is placed over the fabric on the table against registration stops, ensuring accurate pattern fitting. Print paste is poured on to the screen edge nearest the operator and is spread with a squeegee over the surface of the screen so that colour is pushed through the open parts. The screen is moved until one colour has been applied to the cloth. For application of other colours, the process is repeated with different screens.
With the growing importance of screen printing, the hand operation has been largely replaced by mechanical methods. In some machines, the screens are flat, as in hand printing; others employ rotary screens.
RUICO is a company specializing in textile emulsion , and has cooperation with mining companies in many countries. If you have any needs in this regard, please contact us
Jimmy yuan
Zhejiang Ruico Advanced Materials Co., Ltd. (Stock No.873233)
Add: No.188, Liangshan Road, Linghu Town, Nanxun District, Huzhou City, Zhejiang Province, China 313018
Phone: +86 (572) 2903236
Fax: +86 (572) 2905222
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Website: www.ruicoglobal.com
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