Wednesday, December 31, 2014

Manmade fiber

Definition: A class name for various fibers (including filaments) synthetically produced from fiber-forming substances which usually refer to all chemically produced fibers to distinguish them from truly natural fibers. i.e. polyester, acetate, polyamide, glass, carbon, nylon, spandex, olefin etc.

Different Types Man Made Fibre
Acetate • Triacetate • Art silk • Bamboo • Lyocell Rayon • Modal Rayon • Rayon
Glass • Carbon (Tenax) • Basalt • Metallic
Acrylic • Aramid (Twaron • Kevlar • Technora • Nomex) • Microfiber • Modacrylic • Nylon • Olefin • Polyester • Polyethylene (Dyneema • Spectra) • Spandex • Vinylon • Vinyon • Zylon .

Monday, December 29, 2014

Rubbing Fastness

  Rubbing fastness: Rubbing fastness is the resistance to fading of dyed textiles when rubbed against a rough surface.the fastness to crocking or rubbing is widely used on a variety of fabric to evaluate the transfer of surface dye from the test fabric when it is applied surface friction or rubbed against a rough surface,two types of rubbing test are done-
Crock meter
Grey scale staining
 Test specimen 15cm x 5cm (may be more, it has no effect) is placed on the base of the Crockmeter.
 A square of white test cloth (5cm x 5cm) which is of plain weave, desized, bleached but without finished cotton fabric (as ready to dye)is taken.
 White test cloth is attached to the finger of the crockmeter.
  rubbing is done, to and fro 10 cycle at 10seconds, i.e.20 rubs in 10s and finger pressure on the specimen is 9N.
 For testing dry and wet rubbing, separate sample is used.
 Rubbing test is done both for warp way and weft way.
 For wet rubbing, sample is dry but white test cloth is wet. for wetting,M:L ratio is maintained not less than 1:50,water is drained after wetting and not squeezeed.

Saturday, December 20, 2014

Vat dyes

Indigo dyes, the vegetable dyes known to ancient Indians, was dyed on textile materials in wooden vats (tubs). Dyes similar to indigo in their application are called ‘vat dyes’. Actually indigo is the first number of vat dyes.
Bond formation with fibers:
They are insoluble in water so they cannot be directly applied on cottons or other fibers. They have to be temporarily converted into a water soluble form, having sufficient affinity for fibers. During the dyeing process, it is this soluble form of the dye that is applied on cotton, followed by re conversion of the soluble form into the original insoluble form. As a result, the insoluble dye is trapped in the fiber substance and cannot come out during soaping or any other wet treatments. So the conversion of water insoluble dyes to water soluble dyes and then re conversion of water soluble dyes to water insoluble dyes are carried out in two steps-
01. Solubilizing step
       (A) Reduction of the dye into the weakly acidic leuco form
       (B) Salt formation by neutralizing these weakly acidic leuco vat dyes by NaOH to give a water soluble product. This is called solubilizing step.
Reduction followed by solubilizing is called ‘vatting of the dye’. On reduction, indigo gives indigo white, a colorless and water insoluble product, this dissolves in a solution of NaOH.
02. Oxidation step.

Friday, December 19, 2014

Azoic dyes/Azoic colors

Azoic dyes are insoluble azo dyes produced in situ on the fiber. In this dyeing process two components are necessary. The first component is Naphthol and the second is Fast base.
The first component which is nearly colorless or faintly yellow or brown in color has to be dissolved in water, containing NaOH and applied to cotton as if it were a direct dye but at room temperature and not at the boil.
The second component has to be subjected to a section called diazotization and then applied to cotton which has already been treated with a first component. These two compounds react (couple) with each other almost immediately, producing usually a bright colored pigment, which is insoluble in water. Since an azo group (—N=N—) is formed during the coupling of the two components, so these dyes are called ‘Azoic dyes’. They have excellent washing fastness.

Thursday, December 18, 2014

Optical whitener/Optical brightener:

There is a special class of dyes which are similar to direct cotton dyes in that they may be applied like direct dyes. But these are colorless compounds having affinity to cotton. These dyes are called ‘White dyes’.
These have the property of fluorescence, by virtue of which they absorb ultraviolet light and convert it into visible light and brighten the textile fabric; therefore these are called ‘Fluorescent brightening agents’.
Since this whitening is an optical effect, they are also called ‘Optical brightening agents’.
Examples- Fluorescent purple 2G, Leucophor B, Glow white etc.

Wednesday, December 17, 2014

Water insoluble dyes

They are not soluble in water and hence they cannot be applied directly on textile like direct dyes. They have to temporarily convert into a water soluble form, which must have higher affinity to cotton than its water solubility and then applied to cotton at an appropriate temperature and then heating the solution while stirring the yarn so that it picks up the dye uniformly to give even dyeing effect. Finally the water soluble form should be reconverted into the original insoluble form after being taken up by the cotton. This dye has good washing fastness. They will not bleed out in the hot soap solution used in washing of the dyed clothes.

Tuesday, December 16, 2014

Otto N. Witt theory of Chromophore and Auxochrome

Otto N. Witt discovered the theory of Chromophore and Auxochrome in 1876. He explains-
All organic compounds that contain certain unsaturated groups which are responsible for color are called chromophore.
Examples-  —N=O (Nitroso),  —NO2 (Nitro),   —N=N— (Azo),   >C=C< (Ethylenic),  >C=O (Keto)                                                                                         
01. Independent chromophore – When a single chromophore is sufficient and does not need auxochrome to impart color to the compound, then it is called independent chromophore.
Examples- —N=O (Nitroso),  —NO2 (Nitro),   —N=N— (Azo) etc.
02. Dependent chromophore – When more than one chromophore is required to impart color in the chromogen, then it is called dependent chromophore.
Examples- >C=C< (Ethylenic),  >C=O (Keto) etc.
They are color helping or color intensifying groups. The auxochrome by itself does not produce color but it-
(i)            Generally deepen the color of a chromogen.
(ii)           Helps the chromogen to adhere to the textile fiber.

Monday, December 15, 2014

Sources of dyes:

01. Animal origin:
Cochineal - obtained from an insect. It is extractable in water to give scarlet, crimson and orange color. It is expensive source.
02. Plant origin:
(i) Log wood – Obtained from the heart of the campeachy tree to give black and navy blue shades.
(ii) Madder/Alizarin – From the root of madder; on fermentation red color is obtained.
(iii) Indigo – The leaves of indigo bearing plants yields a yellow juice that rapidly turns blue when exposed to air.
03. Mineral origin:
(i) Prussian blue, (ii) Chrome yellow, (iii) Ultramarine etc.
04. Synthetic origin:
All natural dyes are replaced by synthetic dyes. They are cheaper and more permanent. The first synthetic dye is ‘mauve’ discovered by Perkin from aniline to quinine. Such aromatic hydrocarbons are obtained from coal tar, petroleum, crude oil etc.

Saturday, December 13, 2014

Classification of Detergents:

Most common types of detergents are-
01. Anionic detergent-
Those detergents which produce anion (R-) in water or solution are called anionic detergents. Anionic detergents dissociate into a long chain anion which acts as the ‘hydrophilic’ end and the long chain carbon as the ‘hydrophobic’ end.
Examples- Alkyl benzene sulphonates (ABS), Alkyl sulphates, Alkyl benzene ether sulphonates (ABES), Sulphated fatty alcohols.
02. Cationic detergent-
Those detergents which produce cation (R+) in water or solution are called cationic detergents. These detergents have no strong detergent characteristics but have strong germicidal properties.
Examples- Quartenary ammonium compounds.
03. Non-ionic detergent-
It don’t contain any ionic molecule. They produce little foam. They possess excellent soil removal and grease emulsification characteristics.
Examples- Alkyl aryl ethylene oxide derivatives, fatty acid amides, aliphatic polyhydric alcohols esters.
04. Amphoteric detergent-
Those detergents which contain both cationic as well as anionic groups are called amphoteric detergents. They are used in the manufacture of paste, shampoos, cosmetics, emulsion, paints etc.
Examples- Lauryl sarcozinate.

A dye may be defined as a colored substance, which has an affinity to the substrate to which it is being applied and then imparts a permanent color to that which is not removed by rubbing or washing with water, soap or on exposure to sunlight.

 Properties of dyes:

01. It must have a suitable color.
02.  It must have the capability of being fixed to the fabric directly or with the help of certain reagents called ‘mordant’.
03. It must be easy to apply on fabrics.
04.  The affinity of the dye is connected with the linearity of the molecular structure of the dye, so that they can lie with their long axis parallel to the axis of cellulose molecule, which is also linear.
05.  For a direct dye to have affinity for cellulosic fibers, the aromatic rings present in the dye molecule must be coplanar.
06.  Resistant to dilute acid and alkali.
07. After dyeing, the dye must not loosen the strength of the fiber.

Monday, December 8, 2014

 A textile was originality a woven fabric but the term of textile and the plural textile are now also applied to fiber, filament and yarns, natural and manufacturing and most  producer for which these are a principal raw material.



A manufactured assembly of fiber and/or yarn that has substantial surface area in relation to its thickness and sufficient cohesion to give the assembly useful mechanical strength is called fabric.
Loom: A weaving machine is technically termed as a loom. Loom is a device or machine in which interlacement of warp yarn and weft yarn is performed and thus fabric is product.

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