Digital ink formulations for the fabric printing (future of the textile processing)
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The document discusses the formulation and production of digital inks for inkjet printing, outlining key components such as high purity pigments, rheology modifiers, and various additives that influence ink performance. It compares dye-based and pigment-based inks, detailing their properties, preparation processes, and challenges related to stability and image quality. Additionally, specific technical methods for improving ink performance and a list of references on digital ink technologies are provided.
Digital ink formulations for the fabric printing (future of the textile processing)
- 2. Digital ink formulation Submitted to Dr. B.S. Butola Submitted by Vivek Yadav
- 3. Basics about Digital inkjet printings
- 4. INK & IT’S USES
- 5. BRIEF COMPARISON BETWEEN PRINTPASTE &INKJET INKS
- 6. • High Purity • High Solubility • Optimum rheology properties of solution •Optimum Particle size and distribution • Conductivity • Surface charge and polarity • Foaming properties • pH WHAT WE EXPECT FROM COLORANTS ?
- 7. Ink Development Accelerated shelf life tests Drop analysis Formulation development Dye purification Print head analysis – Materials compatibility Degassing (cartridges) High precision filtering Ink mixing – different batch volumes Purified powder dye mixing in glove box Raw materials - high precision weight scale Dye synthesis and purification INK PRODUCTION BASIC OPERATIONS FOR INK FORMULATIONS
- 8. DYE INK Vs PIGMENTS INK
- 9. General Pigment Ink Formulation ( simple and versatile) o A pigment dispersion o A polymeric binder o Water, for aqueous inkjet inks o Aco-solvent, for wetting and adhesion to the substrates and jetting properties (pyrolidone, propane diol, etc) o Surfactants o Humectants o An antifoamagent o Aviscosity control agent( 20 cps high molecular weight water soluble polymers ) o Abiocide
- 10. Pigment color dispersion Selectionof pigments based on thecolor gamut , and light fastness Pigments should be dispersed Dispersionstability Self dispersing. Polymeric dispersantassisted. Particle size; 0.05 -0.15 micron Big particles ? 1. Settling 2. Clogging 3. Startup and jetting problem
- 11. Image quality( small vs big particle size) Big vs smallparticles Big ; higher colour density Small ? Effective use ofcolour Better for glossy substrate SOLID CONTENT 10-40 %; higher thebetter (Typical is 20 %) VISCOSITY AND SURFACE TENSION Low viscosity Low viscosity in pigment dispersion means leaving more room for other ingredients such as polymeric binders and greater ease in maintaining overall viscosity of the final inks Higher surfacetension High S.T can be controlled by surfactant but low S.T cant be balanced well
- 12. Other essential ingredientsBINDERS Incorporating polymeric binder in general difficult; these are film forming substances. Low T.g ? To keep ink soft and prevent clogging at relatively low temperature Reliable jetting(To maintain the low viscosity and formulation space for jetting reliability) Random or blockco-polymers Wateras the carrier ; 50-80% Co-solvent( rheology modifiers) , Propanediols (1,2;1,3, 2,2), 2- pyrrolidone,PEG, PPG, glycerol,etc. Surfactants High HLB for colloidalstability Low HLB for low surfacetension ink can wet the nozzle capillary Maintain the meniscus at the nozzletip reliable jetting Short-chain ethylene glycol based nonionic surfactants
- 13. Typical ink Formulation • 3-6% dye • 70-80% water • 20-25% Humectant(DEG/2-Pyrrolidone) • Surfactant (perflouro based) • Penetrating agent (Hexane-1,6 diol) • Preservative (methyl-isothiazolones) • Corrosion Inhibitors (Benzothiazoles) • Electrically conducting Lithium salts Viscosity ~1-3 centipoise Surface Tension ~ 35 dynes per cm
- 14. Pigment inks; pros & cons
- 15. Types of pigment inks and their process route
- 16. Disperse ink Expectations Dye should have good dispersibility (physio-chemical property) Reduction clearingability Of course good all round fastness
- 17. Desperse Ink preparation Removalof saltsand otherorganic impurities High pressure milling for good dispersion and controlling particlesize Purification Ultracentrifugation Ultrafiltration Reverseosmosis Desperse dye formulation Aqueousdispersions Solids ~ 20% Particle size ~ 0.1-0.25micron Viscosity ~ 10-50 mPa.s
- 18. Selection of dispersing agents
- 19. Disperse ink Process flow Specific Pretreatment Sodium alginate = 100-200 gm/kg Citricacid = 0-2 gm/kg Pad and dry Fixation Could be Thermosol process HT steam ~ 1800 C Washing Cold wash • Soap neutral (1-2 gpl) ~ 400 C • Reductionclearing ~ 800 C 1-2 gpl sodium hydrosulphite 2 gpl NaOH 1 gplsurfactant • Hot water wash ~400 • Cold wash • Dry
- 20. Disperse direct pros & cons
- 21. Disperse sublimation ; pros & cons
- 22. Reactive Dye Ink Substrate ; cotton viscose silk; Ink chemistry; • MCT • Vinyl sulphone • Di- chloro trizine dyes ? Factors affecting stability of ink Ionic nature; i. Amine and hydroxyl group moiety can react with reactive dye. ii. water-soluble organic solvents may possibly react with reactive dyes. Hydrolysis I. The role of sodium carbonate is as a catalyst to promote hydrolysis by increasing pH.
- 23. Water based inks……START UP PROBLEM ? Near nozzleevaporationof watermeans increased solidsat the surface creating an obstruction flow and thus formationof drop and dropsize, leading tostart up failure, and poor imagequality SOLUTION …….rheology modifiers …? Lessvolatileorganicsolvents inoptimum concentration are added, this reduces rateof evaporation, such as, EG, DEG, 2- butanol, urea, etc.
- 24. Pretreatment for inks formulation beyond conventional pre-treatment
- 26. Specific pretreatment along with Post treatments- REACTIVE DYES
- 27. WHAT IF NOT PRETREATMENT AND AFTER PRETREATMENT
- 28. POST TREATMENTS FOR DIFFERENT INKS
- 29. Some commercial digital inks
- 30. References 1. Yoshiki Akatani technical brochure, Fixing of Dye on Various Textile and Inkjet Printing, Nippon Kayaku Co. (2005). 2. Nagase Sangyo Co., in the text Textile Printing Seminar (1999). 3. Akira Asai et al., `Impact of an ink drop on paper', IS&T NIP7 Proceedings (1991). 4. Burkinshaw, D.K., Dyes and Pigments, 33, 11, 1887. 5. Piriya Putthimai et al., `Comparison of textile print quality between inkjet and screen printing', Surface Coating International Part B, B1, 88, 1-82, March 2005. 6. Yasuhiko Kawashima et al., `The development of new disperse dye inks for inkjet textile printing', IS&T NIP19 Proceedings (2003).