Dyeing

Pr. LADHARI Néji Professor of textile Engineering Higher Institute of fashion of Monastir [email protected]

Advances technologies of dyeing and functionalization in textile. 1

09H00 – 09H30

Conference title:

Plenary conference 8

Email

Contens Introduction, Dyeing Process, Functionalization Process.

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Introduction:

- Create new effects,

- Reduce the consommation of water, - Reduce the consommation of energie, - Reduce the pollution.

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Introduction:

Advances cover the following components: - Dyes, - Dyeing, - Finishing (functionalization) process, - Wastewater treatments.

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Dyes :

Some advances in dyes: Chromic materials, - Functional dyes (UV- absorbent, anti-microbial and water-repellent dyes). -

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Dyes : Chromic materials: -Are obtained by the application of dyes: Their colors change with temperature (thermochromic), light (photochromic), pressure (piezochromic), etc. -These dyes are microencapsulate, applied to fabric like a pigment in a resin binder. 6

Dyes :

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Dyes : Functional dyes : - UV- absorbent, - Anti-microbial, - Water-repellent dyes, - Etc…..

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Dyeing process : 1. Advanced DENIM concept, 2. Supercritical fluid dyeing (SFD) , 3. Ultrasound technology, 4. Ultraviolet technology, 5. Ozone technology 9

Dyeing process :

1. Advanced DENIM concept: Traditional dyeing with indigo : Denim, -

Requires chemical auxiliaries (not eco-friendly), Uses a lot of water, Uses a lot of energy, Generates a lot of waste cotton.

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Dyeing process :

- ADVANCED DENIM, compared to a conventional denim dyeing process, allows savings in water, in cotton waste and in energy (Denim-OX, Pad/Sizing-Ox).

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Dyeing process :

2. Supercritical fluid dyeing (SFD) :

This technology uses carbon dioxide (CO2) as a dyeing medium that can be collected and recycled. It also does not require drying, which is expected to contribute to the reduction of energy use.

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Dyeing process : - A substance is dissolved in the supercritical fluid, the solution flowed past a solid substrate, and is deposited on or dissolves in the substrate. - Carbon dioxide also dissolves in many polymers, considerably swelling and plasticising them and further accelerating the diffusion process.

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Dyeing process :

Advantages: -No damage of the fibre, -Shortened process and dyeing time, -Low dye and chemicals consumption, -No water consumption, -No drying process, -Energy saving (short process, low heat, etc).

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Dyeing process :

3. Ultrasound technology: This technology will allow accelerating processes and obtaining the same results as existing techniques but with a lower temperature, low dye and chemical concentrations.

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Dyeing process :

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Dyeing process :

Three main phenomenons: • Dispersion: breaking up of micelles and high molecular weight aggregates into uniform dispersions in the dye bath, • Degassing: expulsion of dissolved or entrapped gas or air molecules from fiber into liquid and removal by cavitation, thus facilitating dye-fiber contact, • Diffusion: accelerating the rate of dye diffusion inside the fiber by piercing the insulating layer covering the fiber and accelerating the interaction or chemical reaction, 17

Dyeing process : Some of the benefits of using of ultrasonics in dyeing can be listed as below: • Energy savings by dyeing at lower temperatures and reduced processing times, • Environmental improvements by reduced consumption of auxiliary chemicals, • Lower overall processing costs (due to less energy and chemical consumption). 18

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Dyeing process :

4. Ultraviolet technology:

• UVA: Long-wavelength: covers the range 315-400 nm. 90% of UVA reaching the earth’s surface (UVA-I: 340nm - 400 nm, UVA-II:315nm - 340nm), • UVB: Medium-wavelength: covers the range 280-315 nm. Approximately 10% of UV radiation reaching the Earth’s surface, • UVC: Short-wavelength UVC covers the range 100-280 nm. They are the most dangerous (completely absorbed by the ozone layer). 20

Dyeing process : Photomodification of the surface fibers, by UV treatment, can allow : • More dye to become fixed, producing deeper shades, • More rapid fixation of dyes, • Dye fixation under less severe conditions (lower temperature). 21

Dyeing process :

5. Ozone technology: Ozone is a very powerful oxidizing agent, which is able to participate in a great number of reactions with organic and inorganic compounds.

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Dyeing process :

Increase in dyeability caused by ozonation process depends on the following parameters: - pH: at pH9 the indirect pathway dominates. The pH influences the generation of hydroxyl radicals. -Temperature: ozone becomes less soluble (ozonation efficiency, temperature rise increases the reaction rate), -Ozone dose: ozonation efficiency increases, -Water content of the fiber:

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Dyeing process :

The beneficial effects of this treatment are: -Increasing on dyeability, on color parameters, light fastness characteristics, and the standard affinity.

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Functionalization process : 1. Plasma technology, 2. Gamma irradiation technology, 3. E-beam irradiation technology, 4. Ion implantation technology.

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Functionalization process :

1. Plasma technology:

The plasma is referred to as the fourth state of matter (in addition to solid, liquid, gaseous)

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Functionalization process :

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Functionalization process :

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Functionalization process :

2. Gamma irradiation technology: Gamma rays: frequencies above 10 exahertz (or >1019 Hz), energies above 100 keV and wavelengths less than 10 picometers (less than the diameter of an atom). Gamma rays are ionizing radiations that interact with the material by colliding with the electrons in the shells of atoms. They lose their energy slowly in material being able to travel through significant distances before stopping. 29

Functionalization process : The free radicals formed are extremely reactive, and they will combine with the material in their vicinity. The irradiated modified fabrics can allow: - More dye or pigment to be fixed, producing deeper shades, - More rapid fixation of dyes at low temperature.

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Functionalization process :

3. Electron-beam irradiation technology: E-beam processing is interesting as it offers the possibility to treat the materials without solvent, at normal temperature and pressure. Energy of the electrons in gas plasma is in the range of 1-10 eV, E-beam accelerators generate electrons with energy (300 keV to 12 MeV). These electrons are used to modify polymer materials through direct electron-to-electron interactions. These interactions can create active species such as radicals. 31

Functionalization process : Industrial e-beam accelerators with energies in the 150300 keV range are in use in applications where low penetration is needed, such as curing of surface coatings. Accelerators operating in the 1.5 MeV range are used where more penetration is needed. E- beam machines have high-dose rate and therefore short processing times. While they have limited penetration compared with gamma irradiation. 32

Functionalization process :

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Functionalization process :

4. Ion implantation technology: Ion implantation is an innovative production technique with which the surface properties of inert materials can be changed easily. Ion implantation can be used to induce both surface modifications and bulk property.

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Functionalization process :

Ion implantation consists of basically two steps: - Form plasma of the desired material, - Extract the positive ions from the plasma and accelerate them toward the target,

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Functionalization process :

Potential textiles:

microcapsules

based

finishes

• Flame retardants, • UV absorbers, • Chromic materials, • Antimicrobial finishes, •Thermoregulatory finishes, • Etc… 36

for

Functionalization process :

Ionized fabric for health:

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Functionalization process :

Ionized fabric to help women sleep better :

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Functionalization process :

Thank you Pr.LADHARI Néji LGTex, University of monastir [email protected] 39

Functionalization process : References: -http://dx.doi.org/10.5772/53912: The Use of New Technologies in Dyeing of Proteinous Fibers, - http://dx.doi.org/10.5772/53912. -http://www.advanceddenim.clariant.com/index.php/products/dyeing.html, -http://www.explainthatstuff.com/thermochromic-materials.html, -http://textiles.archroma.com/advanced-denim/, -http://fashionista.com/2015/11/new-denim-advances,

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Functionalization process :

Plasma only reacts with the fabric surface and does not affect the internal structure of the fibers. It can modify the surface properties of textile materials, deposit chemical materials (plasma polymerization) to add functionality, or remove substances (plasma etching) from the textile materials.

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Functionalization process :

The coloring and decoloring modes are controlled by aggregation and separarion leuco dye and a long-chain type developer by heating, as shown. 42

Functionalization process : The use of Nanotechnology (NT) in producing hydrophobic, superhydrophobic and antimicrobial finishes is dealt with alongside coating and lamination techniques. The NT at the molecular level can be used to develop desired textile characteristics, such as high tensile strength, unique surface structure, soft hand, durability, water repellency, fire retardancy, antimicrobial properties, and the like. Indeed, advances in NT have created enormous opportunities and challenges for the textile industry, including the cotton industry.

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Functionalization process : Wastewater treatments Also, many wastewater treatment processes are developed in recent years, because now, water is the most important element in textile finishing. Today, it constitutes an increasingly expensive medium. The most recent processes are: The membrane bioreactor (MBR) technology is a highly promising technique for industrial wastewater purification. Therefore MBR effluents can be of a quality suitable for direct recycling or after further purification by additional post-treatment steps.

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Functionalization process : Advanced Oxidation Processes (AOP) are characterized by production of OH• radicals and selectivity of attack which is a useful attribute for an oxidant. The versatility of AOP is also enhanced by the fact that they offer different possible ways for OH• radicals. Generation of HO· is commonly accelerated by combining O3, H2O2, TiO2, UV radiation, electron-beam irradiation and ultrasound. Of these, O3/H2O2, O3/UV and H2O2/UV hold the greatest promise to oxidize textile wastewater. Ozone application can be generalized into two; a powerful disinfection and a strong oxidant to remove color and odor, eliminating trace toxic synthetic organic. O3 and UV radiation could complete the oxidation reaction by supplement the reaction with it. UV lamp must have a maximum radiation output 254 nm for an efficient ozone photolysis. The O3/UV process is more effective when the compounds of interest can be degraded through the absorption of the UV irradiation as well as through the reaction with hydroxyl radicals. 45

Functionalization process :

Different ionizations of plasma gas for textile treatment: • Glow Discharge: It is the oldest type of plasma. The methodology applies direct electric current, low frequency over a pair of electrodes. • Corona Discharge: It is formed at atmospheric pressure by applying a low frequency .The corona consists of a series of small lightning-type discharges. • Dielectric-Barrier Discharge: DBD is produced by applying a pulsed voltage over an electrode pair of which at least one is covered by a dielectric material. 46

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