Pigment printing - Textile Printing

Pigment printing TEXTILE PRINTING:  It can be described as a localized form of dyeing, applying colorant to selected areas of the fabric to build up the design.  Textile printing, like textile dyeing, is a process for applying color to a substrate.  However, instead of coloring the wholesubstrate (cloth, carpet or yarn) as in dyeing, print color is applied only to defined areas to obtain the desired pattern.  Dyeing can hold single color where as printing can handle 12 to 20 colors in single go. Pigment printing: “A fabric that has been printed with a paste made of an insoluble pigment mixed with a binder and a thickener.”  In pigment printing, insoluble pigments, which have no affinity for the fiber, are fixed on to the textile with binding agents in the pattern required.  Pigment printing is most economical printing process and allows maximum output of goods because of the elimination of washing off, quick sampling and high printing speeds.  It is not possible to apply it directly on the fabric. Binder must be used to apply the pigment dye on the fabric. Printing can simply be classified according to technique, fiber type and dye class:  As, Chart Describes major portion of textile printing is covered by Pigment Printing so it becomes an important topic to discuss.  To print on different substrates different chemistry is required for example printing on natural cellulose is majorly done with reactive dyes.  Polyester is printed with disperse dyes.  Cotton is printed with sulfur dyes.  But, Pigment printing can be applied to various type of fibers like Cotton, Polyester, Blend PC, Polyamide and many more. Pigment Printing process  Pigment printing has gained much importance today and for some fibers (e.g. cellulose fibers) is by far the most commonly applied technique. Pigments can be used on almost all types of textile substrates and, thanks to increased performance of modern auxiliaries, it is now possible to obtain high-quality printing using this technique.  Pigment printing pastes contain a thickening agent, a binder and, if necessary, other auxiliaries such as fixing agents, plasticizers, defoamers, etc. Pigment Printing process  White spirit-based emulsions, used in the past as thickening systems, are used only occasionally today (mainly half- emulsion thickeners).  After applying the printing paste, the fabric is dried and then the pigment is normally fixed with hot air (depending on the type of binder in the formulation, fixation can also be achieved by storage at 20°C for a few days).  The advantage of pigment printing is that the process can be done without subsequent washing (which, in turn, is needed for most of the other printing techniques). Pigment Printing Process: Pre-treatment ↓ Printing (with binder and fixer) (roller/rotary printing) ↓ Drying ( Drying the printed fabric) (90-100%/110-120°C) (dryer) ↓ Curing (Fixation of the printed dye or pigment) (cotton 140-160°C/110-120°C 3-5 min) (polyester 160-220°C , 30-60s) (stenter) Steps of printing process: A Typical Printing Process Involves the Following Steps:  Color paste preparation when printing textiles, the dye or pigment is not in an aqueous liquor, instead, it is usually finely dispersed in a printing paste, in high concentration.  Textile Printing The dye or pigment paste is applied to the substrate using different techniques, which are discussed below. Steps of printing process:  Fixation Immediately after printing, the fabric is dried and then the prints are fixed mainly with steam or hot air (for pigments). (Conversion of binder monomer into polymer).  After-treatment this final operation consists in washing and drying the fabric (it is not necessary when printing with pigments or with other particular techniques such as transfer printing). [...]... cleanly to the material By converting the screen -printing process from semi-continuous to continuous, higher production speeds are obtained than in flat bed printing Typical speeds are from 5 0-1 20 yards per minute rotary screen printing machine Advantages of Pigment Printing:  Applicable to natural and synthetic fiber  Pigment printing is most economical printing process and allows maximum output of... sampling and high printing speeds  The advantage of pigment printing is that the process can be done without subsequent washing  Simple technical process without wet after treatment  Pigment printing allows maximum output of goods  Fastness properties are good to average  Well defined design can be produced by pigment printing Disadvantages of Pigment Printing:  Pigment printed textile wears are... of pigment printing: A pigment printing system consists of three essential components:  Pigment dispersion: Specific pigments are treated in a grinding mill in the presence of suitable non-ionic surfactants A particle size of 0. 1-3 μm is typical Generally, the pigment pastes are aqueous based and contain the dispersing agent, humectants (to prevent evaporation and drying out)  Binders and cross-linking... screen printing:  For each color in the print design, a separate screen must be constructed or engraved  The modern flat-bed screen -printing machine consists of an in-feed device, a glue trough, a rotating continuous flat rubber blanket, flat-bed print table harnesses to lift and lower the flat screens, and a double-blade squeegee trough  The in-feed device allows for precise straight feeding of the textile. .. Rotary screen printing:  Rotary screen printing is so named because it uses a cylindrical screen that rotates in a fixed position rather than a flat screen that is raised and lowered over the same print location  Rotary presses place the squeegee within the screen These machines are designed for roll-to-roll  printing on fabric ranging from narrow  to wide-format  textiles  In rotary printing, the... (polymers): The binders used in pigment printing systems are film-forming substances made up of longchain macro molecules which, when heated with a suitable acid-donating catalyst, form a three-dimensional structure in the pigment  Thickeners and auxiliary agents: These give the required print thickening power (rheology) Binders:  Binders plays key role in pigment printing Binder are monomers which... lead  Inert  pigment: TiO2 According to Chemical Nature  Organic pigment:  Azo pigment  Diarylide orange and yellows  Phthalocyanine  Hasna yellow  Inorganic pigment Printing process:  Printing process may be further divided into two steps: 1 Preparation of the print paste 2 Printing the fabric Typical Recipe for Pigment Printing: Soft Water                        g/Kg   700 Anti Foamer  ... also added to the textile pigment printing paste and that is called fixer Fixers are mostly formaldehyde based, which helps in strengthening of binder to hold on pigment The working of binder that how binder sandwiches pigment in between itself and substrate As, nearly 90 to 95% of pigment is successfully entrapped in between so no need of washing as it was required in case of reactive printing to wash... printing to wash off unfixed dye This is big advantage of pigment Printing methods: A decorative pattern or design is usually applied to constructed fabric by:  Screen printing method 1 a b 2 Rotary screen methods Flat screen methods Roller printing method Screen printing method:  Screen printing is by far the most popular technology in use today  Screen printing consists of three elements:  The screen... sensitible to crushing during roller printing  Rubbing fastness is  Pigments are medium completely fast to dry cleaning  http://www.swastiktextile.com/rotary_print ing_machine.html  http://textilelearner.blogspot.com/2012/01/ rotary-screen -printing- machine-working.html . the other printing techniques). Pigment Printing Process: Pre-treatment ↓ Printing (with binder and fixer) (roller/rotary printing)  ↓ Drying ( Drying the printed fabric) (9 0-1 00%/11 0-1 20°C) (dryer) ↓ Curing. (Fixation of the printed dye or pigment) (cotton 14 0-1 60°C/11 0-1 20°C 3-5 min) (polyester 16 0-2 20°C , 3 0-6 0s) (stenter) Steps of printing process: A Typical Printing Process Involves the Following. preparation when printing textiles, the dye or pigment is not in an aqueous liquor, instead, it is usually finely dispersed in a printing paste, in high concentration.  Textile Printing The dye or pigment