Vat dye. Vat dyes are a class of dyes that are classified as such because of the method by which they are applied. Vat dyeing is a process that refers to dyeing that takes place in a bucket or vat. Almost any dye, including fiber-reactive dyes, direct dyes, and acid dyes, can be used in a vat dye. Printing on Cotton fabric with Vat dye. Objects: The main object of this process is to print the fabric. To print on the cotton fabric. Recipe. The well-established commercial inkjet ink formulations for cellulosic textile fibres commonly make use of reactive dyes. Cellulosic fibres are also dyed and screen printed commercially with vat dyes, especially for high performance and technical applications. However, inkjet printing with vat dyes remains problematic.
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By this method development of the dyes and fixation on the fabric is excellent.
Printing on Cotton fabric with Vat dye | Textile Study Center
However, there results considerable bleeding or flushing of the colors as well as marking off of the color from the face of the print to the padder roll. In addition, during the expression of excess printing with vat dyes from the fabric by the padder, appreciable amounts of dyestuff bleed into the impregnation solution and subsequently stain the white unprinted portions of the fabric.
When vat dye pigment prints are padded in printing with vat dyes manner, prints of diffuse outline with undesirably stained white areas are obtained. Previous inventors have endeavored to reduce the flushing, bleed and mark off of the dyestuff during the padding operation by using alkali co agulable thickeners as printing vehicles.
Unfortunately, unsatisfactory printing with vat dyes of the print by the reducing solution is obtained printing with vat dyes the result that development of the color during a short steaming is poor. Patent 1, describes the use of methyl cellulose as a thickener for vat dye pastes which are printed on cellulosic fabrics.
The fabric is dried and padded with a liquor consisting of sulfoxylates and potash. The material is then dried and steamed in a conventional rapid ager for five minutes.
The deficiencies of this process are that only dyestuffs which can be developed by the conventional printing process can be used and the time of development to fix the dye is not significantly reduced.
Furthermore, color development of prints made with methyl cellulose thickeners are inferior to prints made printing with vat dyes conventional thickening agents, unless steaming times are greatly increased.
It is an object of this invention to provide for a process of printing vat dyes on fabrics in a rapid manner and a process which may be adapted as a continuous process if desired.
It is a further object of this invention to provide for such a process without the heretofore attendant bleeding, flushing or marking off of the printed colors but on the contrary to provide for such a process which results in clear, sharp and distinct printed color areas.
A further object is to provide for such printing with vat dyes process printing with vat dyes is applicable to most if not all vat dyes and not merely to the heretofore considered printable vat colors.
Vat dye - Wikipedia
printing with vat dyes I have found that these objects printing with vat dyes be attained by printing the vat colors on the cloth in pigment form and in a thickened paste, as more particularly illustrated in the examples, drying, overprinting the entire fabric with an aqueous solution of caustic alkali and sodium hydrosullite, and then within twenty seconds of such overprinting passing the goods into an air-free steam chamber such as the Mather-Flatt type whereby reduction and fixation of the printed vat dye takes place.
From the steam chamber the fabric is subjected to the usual oxidation, rinsing, soaping, rinsing and drying operations, all of which may be carried out in a continuous manner as desired.
The vat dye pigments may be printed by conventional printing equipment such as described in The Principal and Practices of Textile Printing, Knecht and Fothergill, 3rd edition, In practice, I have found that a low solids thickener i.
These thickeners print satisfactorily and have the advantage of not inhibiting the penetration printing with vat dyes reducing agents and alkali when the prints are subsequently overprinted. Other thickeners such as starch, British gum dextrin and textile gum give less sharp prints and inferior color value.
Fabrics may be dried for after-printing by any suitable means such as printing with vat dyes driers or cans. In the overprinting step the alkali and sodium hydrosulfite are applied from a thickened aqueous solution by means of a suitable blotch or stipple engraved roller in order to apply such reagents evenly over the whole surface of the fabric.
USA - Process for printing textile fabrics with vat dyes - Google Patents
This step is similar to other techniques whereby the whole surface of the fabric is treated with chemicals or other agents. The amount of the reagent applied may be varied at will by choice of suitable depths of engraving on the engraved roller so as to regulate the quantity of the gum applied.
For example, printing with vat dyes deeperthe engraving the heavier the application of the agent.