Dyes and dyeing techniques

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Technical English An Introduction to Dyes And Dyeing Techniques Instructor: Dr Quan Thanh Pham Students: Linh Duy Thai Phuc Huynh Tran HCM City, November 21, 2016 Outline ▪ Colorant, dyes, pigments ▪ Dyes classification ▪ Dyeing techniques  A colorant is a substance capable of imparting its color to a given substrate, such as paint, paper or cotton, in which it is present  Dyes and pigments are the most important colorants used to add a color or to change the color of something What are dyes and pigments ?  Dyes are intensely colored or fluorescent organic substances only  They give color to a substrate  They are soluble and / or go through an application process which, at least temporarily, destroys any crystal structure by absorption, solution, and mechanical retention, or by ionic or covalent chemical bonds What are dyes and pigments ?  Pigments are colored, black, white or fluorescent particulate organic or inorganic solids  Pigments are usually dispersed in vehicles or substrates for application COLORANTS Organic (16%) Dyes (75%) Inorganic (84%) Pigmetns (25%) Pigments Terms • Chromophores are color-bearing groups such as C=C, C≡C, C=O, C≡N or N=N, • Chromogen is a chemical compound that is either colored or could be made colored by the attachment of suitable substituent • Auxochromes like OH, OR, NH2, NHR,  Absorb light in the visible spectrum (400-700 nm)  Have at least one chromophore  Have a conjugated system, i.e a structure with alternating double and single bonds  Have resonance of electrons, which is a stabilizing force in organic compounds Chromophore Auxochrome Chromogen Classification of Dyes Chemical structures Application methods In the batch exhaust technique ▪ The entire textile-in continuous contact- the dye liquor ▪ “Exhaust” means the transfer of the dye from bath to the substrate In continuous impregnation ▪ The fabric-a small bath containing the dye solution – (2 rubber-covered rollers) Resist Dyeing ▪ A certain part of cloth is dyed and deliberately prevented dyeing of other parts ▪ Impermeable substances: wax, clay, resin ,… ▪ Include: tie-dyeing, hot wax resist technique,… Tie-Dyeing Technique ▪ The tying or stitching of fabric to prevent the absorption of dye to a particular area  Waxed thread is tightly tied around a chosen area Tie-Dyeing Technique Tie-Dyeing Shibori ▪ An old name of the tie-dyeing technique as a Japanese art ▪ Binding, tying, twisting, stitching, or wrapping of fabric Dyeing Process Preparation Dyeing Finishing Preparation ▪ To remove the natural or synthetic impurities Dyeing • The diffusion from the bath to the fiber surface • The adsorption onto the surface of fiber • The diffusion to the fiber core • The fixation on the fiber Finishing ▪ Permanent press ▪ Water proofing ▪ Softening ▪ Antistatic protection ▪ Soil resistance ▪ Stain release ▪ Microbial/fungal protection e ▪ Video THANK YOU FOR YOU ATTENTION Any Question? Appendix ▪ stilbene ▪ Compare Direct and Acid Dyes The acid groups of direct dyes are not the means attachment to the fiber pH: neutral-acid ( Acid), alkalide –neutral( Direct) [...]... Nitro and Nitroso Sulfur Azo Dyes  60 % of the total dyes  Contain at least one N=N  Use: textile, pharmaceutical, plastic, leather, paper, and printing, industries R, R’ usually are aromatic Anthraquinone Dyes  Important class after azo dyes  Brightness and good fastness, strong absorption bands in long-wavelength region  Have anthraquinone group Indigoid Dyes  One of the oldest organic dyes. .. organic dyes known (5000 years)  Used for dyeing denim jeans and jackets  Have Indigoid group Phthalocyanine Dyes  Have a highly conjugated π-electron system  Stability, flexibility, diverse coordination properties, and improved spectroscopic characteristics  Cu, Fe, Si, Ge, and As in components  Phthalocyanine group Sulfur Dyes and Nitro and Nitroso Dyes One more thing Dye Classes According... cellulose Direct Dyes ▪ Direct Orange 26 Vat Dyes ▪ Water-insoluble pigments ▪ Colorfastness to laundering and light ( because of their water insolubility) ▪ Related to Indigoid or anthroquinone (have between 5 and 10 aromatic rings) ▪ (why they are called dyes: pigment /alkaline solution  watersoluble leuco form (substantivity for cotton) oxidized  insoluble Vat Dyes ▪ Vat Dye Blue 4 Dyeing Techniques. .. Substrates: paper, poly-acrylonitrile, modified nylons, and modified polyesters ▪ On most fibers, except acrylic fibers, have low colorfastness ▪ Usage: for Ink, Paper, Textile ( acrylic fibers), Agrochemicals ▪ Do not applied along with acid or direct dyes Basic Dyes ▪ Basic Brown 1 Direct Dyes ▪ The largest group of dyes ▪ Water-soluble dyes ▪ Anionic dyes with the affinity to cellulosic fibers ▪ Related... brilliance and range of color ▪ Principal substrates: cotton, wool, silk, nylon Reactive Dyes ▪ Reactive blue 5 Disperse Dyes ▪ Water-insoluble nonionic dyes ▪ Azo, anthraquinone, nitro groups ▪ Substantivity for one or more hydrophobic fibers ▪ Substrates: Nylon, cellulose, cellulose acetate, and acrylic fibers ▪ Disperse Red 4, Disperse Blue 27, Disperse Yellow 3,… Disperse Dyes ▪ Disperse Yellow 3, Acid Dyes. .. Related to azo, anthraquinone, triphenyl methane, nitro and nitroso chromophoric groups ▪ The commercially available forms are sodium salts ▪ Good water solubility ▪ Mostly used with: polyamide, wool, silk, modified acrylic, polypropylene fibers,… ▪ Bright color and fastness to light and washing Acid Dyes ▪ Acid yellow 36 Basic Dyes ▪ Cationic dyes ( resulting from the ammonium cation) ▪ Water-soluble... Dyes ▪ Vat Dye Blue 4 Dyeing Techniques ▪ What is Dyeing? ▪ The creating of a new and permanent color, by impregnation of especially a dye onto any material namely, textile, paper or leather ▪ Goal: to provide a uniform coloration for all of fibers forming the material Dyeing Techniques In the batch exhaust In continuous impregnation Resist -Dyeing Tie -Dyeing Shibori … In the batch exhaust technique ▪... Dye Classes According to Application Methods Reactive Vat Disperse Dyes Direct Acid Basic Dye Classes According to Application Methods ▪ Color Index (C.I.) ▪ Each colorant is assigned a C.I., consisting of generic name and a chemical constituiton number ▪ Generic name contains application type, color an identifying number C.I Reactive Dyes ▪ Contain one or more reactive group ▪ Form a covalent bond
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