Fluorescent dyeing is a Kind of advance dyeing system pptx

Fluorescent dyeing is kind of advanced dyeing system

1. Fluorescent dyeing

2. The ability of a substance to absorb light at a specific wavelength and emit it at a higher wavelength is called fluorescence . Optical brighteners or fluorescent whitening agents are added to improve the appearance properties (brightness, whiteness etc.) of printing and writing papers . When light strikes a fluorescent material, some of the electrons acquire energy and a portion of energy is converted into heat. Thus, the emitted light has lower energy as compared to the incident light, which results in longer wavelengths. In contrast, non-fluorescent material either completely absorbs and converts such energy to heat , or instantly releases the energy by emitting light at a wavelength equal to the incident light . Fluorescence

3. 1. Electromagnetic energy from a laser set at the correct wavelength will provide the right amount of energy to an electron in the fluorescent dye molecule. This is the signature excitation wavelength for the molecule. The energy is absorbed by this electron. 2. On absorption of this energy, the electron moves to an excitation state at the next energy level (Es).  3. Finally, this energy is released in the form of a photon (fluorescence) and the electron moves back down to the lower energy level. The amount of energy released will be determined by how far the electron drops down the energy levels which will always be the same in the same fluorescent molecule. This will determine the wavelength of the photon, and the color of the fluorescence observed giving the fluorescent dye its signature emission wavelength How does fluorescence work?

4. Fluorescence occurs when an orbital electron of a molecule or atom relaxes to its ground state by emitting a photon of light after being excited to a higher quantum state by some type of energy. The most striking examples of fluorescence occur when the absorbed radiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, and the emitted light is in the visible region . Fluorescent minerals emit visible light when exposed to ultraviolet light Fluorescence and Phosphorescence

5. Phosphorescence is a specific type of photoluminescence related to fluorescence. Unlike fluorescence, a phosphorescent material does not immediately re-emit the radiation it absorbs. Excitation of electrons to a higher state is accompanied with the change of a spin state . Once in a different spin state, electrons cannot relax into the ground state quickly because the re-emission involves quantum mechanically forbidden energy state transitions. As these transitions occur very slowly in certain materials, absorbed radiation may be re-emitted at a lower intensity for up to several hours after the original excitation

6. The applications of fluorescent textiles are associated with their ability to attract attention, because of the remarkable vivid brilliance of the colors which results from the extra glow of emitted fluorescent light .Fluorescent fabrics may be used for specific aesthetic and fashion purposes, the eye-catching bright colors providing unique creative opportunities for the textile and garment designer. They are also used for functional reasons, assuming special importance in leisurewear, sportswear and work wear. Police, firefighters and other emergency services personnel, and construction workers who require visibility in their work surroundings wear garments with fluorescent colors. Fluorescent dyes have been defined as compounds which both absorb and also emit strongly in the visible region of the electromagnetic spectrum, and which owe their potentials application to their intense fluorescence properties Fluorescent dyes are of much greater importance for application to synthetic fibers such as polyester, polyamides and polyacrylonitrile , sometimes also in conjunction with elastane fibers. The most important textile applications are on polyester and thus the most important fluorescent textile dyes are from the disperse dye class Applications of fluorescent in textiles

7. The brightening effect comes from fluorescence, which depends on the property of certain organic compounds to convert shorter wavelength light in eh 300-400 nm range, into longer, 400-500 nm, wavelength s . A surface therefore containing a fluorescent compound can emit more than the total amount daylight which falls on it, giving an intensely brilliant color. The effect is only operative when the incident rays contain a significant proportion of UV light . 300 350 450 500 600 650 400 700 Emission Absorption Visible light Violet-blue-green-yellow-red Invisible light (UV light) Wavelength (nm) Exhaustion/absorption Fig: Absorption and emission of light by OBA 550 Features of Fluorescent Dyes Fluorescent Dyes are acknowledged for their unique and productive features that include : Highly detectable (some even below 1 part per trillion) Water solubility Extremely low toxicity ratings Fair stability in a normal water environment Excellent fastness properties Displays good stability High color strength

8. Fluorescent dyes to be of practical use must produce a pure color dictated by their absorption and emission spectra. The absorption and emission spectra of a fluorescent dye often approximate to mirror images of one another . The difference between the absorption and emission wavelength maxima is referred to as the Stokes shift (described by Sir Jorge Gabriel Stokes). The Stokes shift is the difference between the absorption peak and the emission peak for fluorophores. Larger Stokes shift is always preferred as long as other properties of fluorescent probes are not compromised. Larger Stokes shift allows the use of broad excitation and emission filters that do not overlap, which increases brightness and sensitivity.

9. Fluorescent Dyeing Padding method/Garments dyeing/knit dyeing Stenter machine/woven dyeing machine PFD fabric of knit/woven construction Cationization

10. Procedure Method Cross-linking agent Application (pH=Acidic,150 º -170 º c,Curing) Fabric pretreatment Pigment dyeing Padding mangle (stenter/woven dyeing machine) One stage application of binder and pigment (Ph<6).Finally curing. Cationization Garments dyeing Two stage application of binder and pigment (Ph<6).First pigment , then binder at acidic media and finally curing Fluoresce-nt dyeing Knit dyeing m/c Reactive fluorescent dye Disperse fluorescent N/A One stage application as reactive dyes. No addition is preferable. Normal dyeing. One stage application of disperse fluorescent dyes. Normal dyeing. Garments dyeing Same as knit dyeing Padding mangle (stenter/woven dyeing machine) One stage application of binder and pigment (Ph<6).Finally curing Cationization Resin treatment Garments dyeing/padding mangle First stage, urea precondensate is prepared and this precondensate is reacted with fabric. Finally curing the urea treated cellulosic fabric Spray technique on denim garments: Resin is applied after whiskering or pp/pigment whiskering Normally with pigment mixture. N/A Pigment fluorescent dyeing

11. Classification of fluorescent dye The dyes are classified according to their structure: fluoresceins, rhodamines, coumarins,pyrenes, cyanines, etc. A fluorophore (or fluorochrome, similarly to a chromophore ) is a fluorescent chemical compound that can re-emit light upon light excitation. Fluorophores typically contain several combined aromatic groups, or plane or cyclic molecules with several π bonds Fluorescence of different substances under UV light. Green is a fluorescein , red is Rhodamine B, yellow is Rhodamine 6G, blue is quinine, purple is a mixture of quinine and rhodamine 6g. Solutions are about 0.001% concentration in water

12. Coumarin derivatives provide the most important industrial fluorescent dyes. Fluorescent coumarins are known which absorb and emit in most parts of the visible spectrum, although most commercial products are yellow with a green fluorescence. This group provides important disperse dyes which allow synthetic fibers, especially polyester, to be dyed in brilliant fluorescent greenish –yellow shades. The molecules of Coumarin 7 because of absorption of blue light appears yellow, consequently it also emits yellow-green light. This is depicted in the form of a graph: Coumarin 7 is a special Fluorescent Dyes as its yellow color because of absorption, is very well complemented by a yellowish-green fluorescence. This is best known for its special brilliant yellow-green appearance

13. The greenish-yellow fluorescent and it’s orange to red halogenated derivatives (eosin) were among the dyes but there practical use was limited by inadequate fastness properties. The brilliant bluish red rhodamines were found to exhibit rather better fastness properties on textiles and they are the most important classes of fluorescent dyes for a wide range of application. The fluorescent colors, which absorb invisible ultraviolet light and turn it into bright visible light, are very rare among fabric dyes. There are none among the commonly available Procion MX dyes. There are several fluorescent acid dyes and a couple fluorescent direct dyes, but nothing that is at all acceptable on cotton. The only really good fluorescent fiber reactive dye is Remazol Fluorescent Yellow FL ; unfortunately, this dye is not for sale anywhere in the world in quantities of less than five kilograms of dye.

14. The term “neon colors” comes from a special property of neon gas produced by neon lighting called fluorescence . Fluorescence, of course, is not limited to exotic lighting or neon gas. Certain materials, including so-called “neon dyes,” can emit intense visible light upon exposure to ultraviolet light. This is what gives these dyes the ability to appear so vibrantly bright when compared with non-fluorescent dyes. Dyes can be bright, but neon dyes are bright and fluorescent. What Makes Neons? Fluorescent textile dyes are available in a wide variety of dye classes including acid, basic, vat, direct, disperse, reactive, and pigment dyes . Unfortunately, in the reactive dye class, only one fluorescent yellow dye is currently available

15. The ease and effectiveness of neon dyeing on fabric depends most on the fiber used. Suitable acid dyes can be used for dyeing nylon, wool, and silk. Basic dyes can be used on acrylic and modacrylic fabrics. Disperse dyes are useful for polyester. For nylon and polyester fabrics, a reasonable selection of “fluorescent” colors is available. Cotton and other cellulosic's, however, have fewer options. The yellow reactive dye can be used, and a fluorescent lime green shade based on yellow can be prepared. Additions of non-neon dyes to the yellow reactive can also be performed, but the fluorescence can be lost. Additionally, basic dyes can be applied on properly pre-mordanted cotton . A commonly used alternative method for cotton involves the application of neon pigments, which are fixed to the fabric using a binder on a stenter machine . Parameter of Neon/Fluorescent dyeing

16. When it comes to dyeing fabrics neon colors, many challenges arise . The major issues involving the finished product are fastness, the range of colors available, and the pH during processing. Generally, good fastness properties are observed and color varieties available for fibers like polyester, One important fact is that during pink disperse fluorescent dyeing because 1% shade is perfect . If you add more than 1% it will not be fixed . The few reactive dye combinations available for cotton yield fabrics with relatively poor light fastness . Neon nylon suffers from light fastness issues as well. Use of neon-pigments on cotton suffers from poor rubbing fastness and the presence of binders can adversely affect the hand. Manufacturing of pigment dyed fabrics is challenging enough that some traditional dye houses won’t perform it. Use of pigments is hard on dyeing equipment, with expensive cleaning often required . Neon-pigment colors can be contaminated by dark shades from previous conventional dyeing operations.

17. The pretreated sample was treated with 5 gm/l catanizer at 50°C temperature for 20 minutes in pH 8.5. Then the dye bath was prepared by 10% and 15% of fluorescent red, fluorescent yellow and fluorescent blue separately and combined in the liquor ratio 1:10. After catanizing, the sample was performed cold wash. Then the sample was added to each dye bath and dyeing was commenced 10 minutes at room temperature then raised temperature to 60°C for 20 minutes. The dyed sample was washed with cold water and treated with 3 gm/l binder for 5 minutes and finally cold wash at room temperature and then dried in oven (Figure 1). Pigment dyeing-Garments dyeing

18. The pretreated sample was treated with 5 gm/l catanizer at 50°C temperature for 20 minutes in pH 8.5. Then the dye bath was prepared by 10% and 15% of fluorescent red, fluorescent yellow and fluorescent blue separately and combined in the liquor ratio 1:10. After catanizing, the sample was performed cold wash. Then the sample was added to each dye bath and dyeing was commenced 20 minutes at temperature 60°C with 3 gm/l binder. Finally the dyed sample was performed cold wash at room temperature and then dried in oven (Figure 2). Pigment dyeing- stenter /woven dyeing machine

19. FLUORESCENT pigment dyeing(Neon dyeing) Process Fabric load Leveling (cationic )-6% 70˚C (2/3˚/min)x 20' Cooling 50˚C Wash-1 (R/T) for 5 min Wash-2(R/T) for 5 min At Room Temperature Color dosing (20'/30') Runtime-1 45˚C (2˚/min)x10' Runtime-2 55˚C (2˚/min)x10' Runtime-3 70˚C (2˚/min)x10'

20. Sample check Shade match Cooling + Bath drain Wash-1 (R/T) for 5 min Wash-2(R/T) for 5 min Wash-3(R/T) for 5 min Formic acid- .3% (Ph-4.5) R/Tx20‘ same bath Binder- 2%(Ph-4.5) R/Tx20' Acid +softener-1% (Ph-5) 40˚C x15' Preferable Fluorescent Color Pink Rose Lemon China lemon Violet(purple)