More Related Content
What's hot (20)
Similar to Assistants used in the printing process (20)
Recently uploaded (20)
Assistants used in the printing process
- 1. An Assignment On Study on the assistants used in the printing process Course Title: Wet Processing II Corse Code: WPE 323 Submitted To: Dr. A K M Saiful Islam Assistant Professor & Head Department of Textile Engineering City University Submitted by: Md. Zahid Hasan ID: 173375179 Batch: 37th Program: BSTE Submission Date: 14th November, 2020
- 2. Introduction: Printing means localized application of dyes on the fabric according to design. For printing it is required to produce printing paste. Printing paste is a viscous paste which is made from pigments, thickeners and many of chemical. A good printing paste is mainly responsible for good printing effect. So it is very important to make a printing paste. There are different types of ingredients are used to make printing paste. Assistantused in printing process andtheir function: 1. Dyes/ Pigments:Dyes or dyestuff may be defined as colorants in which the coloring substance is dissolved in liquid, are absorbed into the material to which they are put in an application for. Pigments consist of extremely fine particles of ground coloring matter suspended in liquid which forms a paint film that actually bonds to the surface it is applied to. Functions: Attraction of dyestuff to the fiber due to presence of auxochrome. To achieve color effect on the fabric. To produce required shade. Examples: Vat, Azoic, Reactive, Direct dye etc. 2. Wetting Agent: Substances which reduce the surface tension of water, thereby allowing it to wet a surface easily, which are otherwise non wettable are known as wetting agents or surface active agents. Functions: To wet the fabric as well as dyestuff. To reduce surface tension of water allowing the dyestuff for easy penetration into fiber. To obtain smooth paste. To dissolve the dyestuff in the paste. Examples: Olive oil, T.R oil, Caster oil, Lissapol N, Animal oil, Glycerine. 3. Solvents/Dispersing agents/Solution acids: This prevent aggregation of the dye stuff molecules in the highly concentrated paste of the dye, solution aids increase the solubility of insoluble dyestuff, solvents increase the color value of the prints, assist dye penetration and helps to get bright design. Functions: To get bright design,
- 3. To assist dye penetration, To spread dye molecules evenly in the paste, Assist dye fixation, To prevent aggregation of dye molecules in the highly concentrated of the dye. To prevent precipitation. To increase solubility of the dyes. To make proper printing shade. Examples: Urea, Glycerine, Desirable, Alcohol, Acetone, Diethylene glycol, Thio diethylene glycol. 4. Thickener: Thickener is a thick mass which imparts stickiness and plasticity to the print paste so that it may be applied on the fabric surface without bleeding or spreading and be capable of maintaining the design out lines. Thickener gives the required viscosity to the printing paste; prevent premature reactions between the chemicals contained in the print paste. Function: To give required viscosity to the printing paste To prevent premature reactions between the chemicals contained in the print paste. To hold the ingredients of the print paste on the fabric Examples: Na-alginate, Fine gum, British gum, CMC. 5. De-foaming agents:De-foaming agents prevent the formation of foam during printing. Function: To prevent the foam generation during printing Examples: Silicone, Defoamers, Sulphated oil, Perminol KB, Emulsified pine oil. 6. Oxidizing agents:Oxidizing agents develop final color in steaming or in the subsequent after treatment, assist in color fixation etc. Function: To develop the final color during steaming or in the subsequent after treatment. Assists to dye fixation. Examples: Sodium chlorate, Potasium chlorate, Sodium nitrate, Resist salt, Ammonium chlorite, Ludigol, Na or K dichromate.
- 4. 7. Reducing agents:Reducing agents destroy color of the fabric. Function: Used for reduction of different dyes. Used for mainly in discharge printing. To destroy color from the ground of fabric. To make the insoluble dyes to soluble. Examples: Sodium hydrosulphite, Stanus chloride etc. Rongolite-C. 8. Catalyst and oxygencarrier: These prevent fibre damage, during steaming; accelerate the final color development by oxidation. Function: To prevent fiber damage during steaming. Accelerate the final color development by oxidation. Reduce the risk of oxidation. Examples: Copper sulphide, Ammonium vanadate, Potassium ferrocyanide. 9. Acids/Alkalis: Acid is used to control PH below 7.0 in the bath. Alkali is used to control PH above 7.0 in the bath. Function: To maintain pH. To develop the color or printed fabric. To fix dye on the fabric permanently. Examples: Organic acid, Alkali KOH, NaOH, Na2CO3, Pottasium carbonate, Sodium bicarbonate, Sodium acetate. 10. Swellingagents:A swelling agent is a three-dimensional network of hydrophilic polymer chains that are chemically or physically cross-linked. Function: To create the big size holes of the fibers. Helps to swell the fiber structure. To reduce crystallinity. Help the easy penetration of dye molecule inside the fiber polymer. Examples: Polyethylene glycol, Phenols, DEGDA (Di-ethylene glycol diacetate)
- 5. 11. Carrier:It is used to swell the fibres so that dyestuff molecules can diffuse in them easily. Function: Used for fixing disperse dyes on polyester or polyester wool blends at temperature below 105oC. Examples: Diphenol, Ortho-phenol, Tri-chloro benzene 12. Miscellaneous agent: It is colourless, solid, crystalline and very soluble in water. It has dye solvent and hygroscopic properties. It also help to wash out thickener film from the fabric after printing. Function: Assist fixation of dyes. Absorb moisture from air. Facilitates subsequent washing off. Examples: Urea, Glycerine etc. Conclusion:In printing operation it is nessesery to used different types of printing asisstant or ingredients. To produce printed fabric or clothes are used different kinds of printing ingredients. In this assignment will be very helpful to know about assistant/ ingredients used in printing operations.