The process of reactive ink printing on cotton fabrics
Pure cotton fabrics have a large proportion in the textile market. The digital printing of such fabrics mainly uses reactive ink to directly print on cotton fabrics that have been pretreated. Below we will briefly introduce the process of reactive ink printing on cotton and other fabrics.
Since cotton fabrics are woven from natural cellulose fibers, there are cottonseed shells, pectin, waxes, pigments, ash and other components on the fibers. These materials must be processed before desizing, scouring, and bleaching, so that the cotton fabric has sufficient adsorption capacity, good whiteness and excellent smoothness, and maintains high strength, which is conducive to the normal progress of subsequent printing process.
As reactive printing is to directly print the reactive ink onto the fabric, the fabric needs to be sizing beforehand. The sizing agent contains paste, urea, dye promoter, color fixing agent, weak oxidizing agent and so on, each of which must be reasonably controlled to ensure sizing quality.
The operating specifications play an important role in reactive printing. Before starting, you are advised to check sanitation, environment (temperature 20 ～ 30 ℃, humidity 50% ～ 70%), air source, guide belt, ink and waste ink etc. After starting the machine, clean the nozzles, guide belts, and wash tanks, and print a test strip to see if the inkjet is smooth. If the condition is not good, use a sponge to clean the surface of the nozzles, until the test strip is normal. Reactive ink is a water-based ink, which contains high-purity reactive dyes, antibacterial agents, PH adjusters, humectants, deionized water, etc. Generally, the use time of the opened ink cannot exceed 3 months.
The steaming process is a vital step in the chemical reaction between reactive dyes and cellulose fibers. Steaming conditions should be strictly controlled, such as temperature, time, and humidity. Steaming conditions are generally 105 ° C for 15min.
After the fabric is steamed, it should be washed with cold water and hot water. It is best to remove the unreacted dyes or hydrolyzed dyes by flowing water. The slurry should be cleaned in the process, otherwise it will affect the touch feel. The amount of soaping agent should be appropriate. If the amount is too high, it will easily cause foam, which will stick to the fabric and cause stains. If the amount is too low, the floating colors cannot be removed. Try to use a non-foaming soap if possible.