Textiles toys

As all of us knows textile has already cross its barriers from traditional apparels to various other fields such as geotech, agritech, industrial application, autotech and sporttech. A lot of books and papers are available on such an application. But apart from these advanced high tech applications textile from ancient times have been used for non apparel applications. One of such application is use of textiles in preparing toys.

Various toys made up from textile materials have been made from the years ago. Today the market for such textile toys is tremendous. In the year 2005-06, the total toy industry was $2.2 billion globally toy industry growing at five per cent. Moreover China is a major player and forms about 70 per cent of the total global toy market.

Typical textile toys are various animal shaped toys, designed pillows, etc are made up of stuff polyfoam beads with outer cloth material of spandex, polyester, etc. These textile toys are easily available in the retail shops and on internet shopping sites with a good variety.

softeners

A Softener is a chemical that alters the fabric hand making it more pleasing to the touch. The more pleasing feel is a combination of a smooth sensation, characteristic of silk, and of the material being less stiff. The softened fabric is fluffier and has better drape. Drape is the ability of a fabric to follow the contours of an object. In addition to aesthetics (drape and silkiness), softeners improve abrasion resistance, increase tearing strength, reduce sewing thread breakage and reduce needle cutting when the garment is sewn.
The application of softening substances turns a hard and brittle fabric into a soft, pleasant textile with which the buyer can expect a high degree of wearing comfort and wearing properties.

Chemistry of Softeners
The continual proliferation of textile softeners can be attributed to their molecular diversity, performance versatility and the multiplicity of fibres, blends and application processes. Based on polarity or ionic nature, softeners are categorised into four basic types:
1) Nonionic softeners.
Mono – di - glycerides
Glycol esters
Stearamides
2) Cationic softeners
Fatty amidoamine acid salts
Quaternary fatty amidoamines
Quaternary tertiary amines
Quaternary imidazolines.
Gemini Surfactants (Bis-Quaternary Ammonium Salt)
3) Anionic softeners
Sulfated triglycerides
Sulfated fatty alcohols
Anionically emulsied glycerides
4) Amphoteric softeners
Imidazoline carboxylate salts
Imidazoline sulfonate salts
5) Special softeners
Polyethylene emulsions
Silicone emulsions
Author: Mukesh R.

phase change materials

Phase change material PCM are thermal storage materials and are use to regulate temperature fluctuations. PCM means incarporating microcapsules into textie structure to store energy and it happens when they change from solid to liquid and dessipiate it when they get changed from liquid to solid.
PCM material : the constituting microcapsules of paraffin, waxes with various phase change temerature depending on carbon number enclosed are of diameter 1-30micro meter.

Author : Miss Supriya Mazge, (SGGSIE&T, Nanded)

Methylene Blue Absorption

Bleaching is the most important process in textile wet processing which gives white goods. Methylene blue absorption is one of the several methods to estimate the bleaching efficiency.

The absorption of methylene blue by cellulose derivative is generally due to the -COOH groups present in oxycellulose formed by alkaline oxidation (due to bleaching agent) but it may also be due to mineral acids which have been dried into cellulose and are not easily washed out.
The method depends upon treating the sample with a methylene blue solution of known strength and buffered to a known pH and determining the concentration of the methylene blue in the solution either by titration with naphthol yellow or by colorimetric method.

Procedure by titration method

A sample of 2.5 gm weight is placed in test tube or small flask. 15cc of methylene blue is added from burette. The titration is carried out at room temperature. 10cc of solution is withdrawn and titrated with naphthol yellow S. The ethylene blue absorbed by sample is calculated in milimoles per 100gm of dry sample.

Colorants

Traditionally, colorants have been classified into dyes and pigments which are being used in the process of coloring materials. Coloration is a physical process whereby we apply dyes to textiles or incorporate pigments into paints, inks and plastics by dispersion.

But today, we can no longer limit colorants to conventional dyes and pigments.

Color means an effect perceived by an observer and determined by the interaction of the three components of light source, object and observer.

Chromatic colorants have selective absorption and scattering of light which vary with the wavelength. So they can selectively modify the spectral power distribution of light falling on them. Achromatic colorants such as black and grey are spectrally non-selective absorbers while white pigments are spectrally non-selective scatterers.

In short, for our understanding, we can say, colorant is a substance that is used to impart colour to objects. But at the same time, the general classification into dyes as soluble and pigments as insoluble, does not hold any ground in recent years.


Why?

If the colorant has an affinity for the substrate (textile, paper etc.) and will become a part of the colored material without the need of an intermediate binder, we consider such a colorant to be a dye. Dyes, whether, direct, vat, disperse, solvent-soluble or any other type, are dyes because a binder is not required to hold them on the material being colored.

On the other hand, the pigment does require a binder so that it is fixed to the substrate as it does not have affinity to the substrate. A pigment applied to a surface without a binder will not adhere to the surface.

Author: Sambhaji Chopdekar, Institute of Chemical Technology, Mumbai.
Source: Billmeyer and Saltzman’s PRINCIPLES OF COLOR TECHNOLOGY (Third Edition) by Roy S.Berns, A John Wiley and Sons Co., USA (2000)

International Conference on Textile Fashion Industry

PAF NISTI International Conference 2008

Pearl Academy of Fashion has organised an internation conference on ‘Sustainability in the Textile Fashion Industry Chain: Crop to Shop’
The dates for the conference are Conference on 28-29 November 2008 and it is hosted at New Delhi campus. The conference endeavors to achieve aim of capturing research and evolving best practices in the realm of sustainability of textile fashion value chain. The theme enables a diversity of research foci and case studies related to sustainability and its connection to fashion; from fashion materials to the policy and environment perspective; design and sustainability; Consumption, disposal, health and ethical issues.
Contact : Dr. Tarun Panwar and Ms. Manpreet Kaur

Website: www.pearlacademy.com/

Top Textile Industries

Here is the list of India’s leading textile industries amongst top 500 companies brought out by the Economic Times.

Rank	2008	2007	COMPANY	CITY	TURN
	Rank	Rank			OVER
1	136	113	Century Textiles & Inds.	Mumbai	3512.74
2	171	233	JBF Industries	Mumbai	2751.55
3	175	153	Arvind	Ahmedabad	2675.62
4	176	175	Indo Rama Synthetics	Delhi/NCR	2671.06
5	182	167	Raymond	Mumbai	2487.21
6	186	166	Vardhman Textiles	Ludhiana	2422.01
7	208	192	Alok Industries	Mumbai	2197.04
8	247	262	S Kumars Nationwide	Mumbai	1759.16
9	254	189	SRF	Delhi/NCR	1702.32
10	258	255	Welspun India	Vapi	1684.15
11	265	244	Garden Silk Mills ^^	Surat	1633.00
12	294	340	Spentex Industries	Mumbai	1429.09
13	320	310	RSWM	Delhi/NCR	1288.69
14	335	324	Century Enka	Mumbai	1193.27
15	349	337	House Of Pearl Fashions	Delhi/NCR	1117.09
16	353		Bombay Rayon Fashions	Mumbai	1108.91
17	358	314	Gokaldas Exports	Bangalore	1097.73
18	360	369	Abhishek Industries	Ludhiana	1091.46
19	418	445	Shri Lakshmi Cotsyn	Kanpur	938.60
20	423	346	Nahar Spinning Mills	Ludhiana	926.62
21	438		Himatsingka Seide	Chennai	892.32
22	439	341	Nahar Industrial Enterprises	Ludhiana	890.25
23	474	418	Sutlej Textiles & Inds	Mumbai	796.41

Turnover, Equity Capital (Eq Cap) are for FY08;
^^Trailing 12 months ending March '08

POLYPROPYLENE

With the present day consumer driving global markets, cost effective quality products with technological advancement and innovative breakthroughs is the only option to sustain. The current market is truly based on Darwin’s principle ‘survival of the fittest’.

The polyester dominated world of textile polymers has started to witness the rise of the new polymer ‘polypropylene’. Due to its good balance in physical and chemical properties there is a significant growth in the use of polypropylene. The raw materials for making PP are olefins, which can be obtained from thermal cracking of selected hydrocarbon feedstock. Polypropylene can be classified as isotactic, syndiotactic and atactic. Among the three atactic PP is amorphous and rubbery whereas remaining two are crystalline. The isotactic form of polypropylene which can be manufactured using Ziegler – Natta catalyst is of commercial importance.

Though the physical properties are much dependent on molecular weight and molecular mass distribution of the polymer the general properties can be found as following.

General & electrical properties-

Thermal conductivity, Wm^-1*C^-1 0.209

Final M.P. 160-170⁰C (purified form: 176*C)

Specific gravity (ASTM D792-64T) 0.905

PP 0.04%

Since it has high crystallinity and absence of polar character PP is resistant to most aqueous & polar media. PP is soluble in xylene, chlorinated aromatic and aliphatic hydrocarbons etc. In solvents like esters, ethers, higher alcohols etc. it is soluble only at higher temperatures.

Applications

polypropylene finds growing applications in technical textiles as stated following

Polypropylene continuous multifilament yarns:

Artificial turf, Conveyor belts, Wrap fabrics & bags, Industrial sewing threads, Cords, ropes, Cigarette filter tips, Filament winding, Bristles etc.

Polylpropylene staple:

Filter cloth, Coated & protective fabrics, Plastic reinforcement, Medical & surgica, Shoe fabrics and other canvass, Cement reinforcement, Carpet backing (non woven), etc

Properties of Polyester

Physical Properties:
The moisture regain of polyester is 0.2 to 0.8 and specific gravity is 1.38 or 1.22 depending on the type of polyester fibres is moderate. The melting point of polyester is 250-300°C. A wide of polyester fibres properties is possible depending on the method of manufacture. Generally as the degree of stretch is increased, which yields higher crystallinity and greater molecular orientation, so are the properties e.g. tensile strength and initial Young’s modulus. Shrinkage of the fibres also varies with the mode of treatment. If relaxation of stress and stain in the oriented fibre occurs, shrinkage decreases but the initial modulus may be also reduced.
Miscellaneous Properties:
Polyester fibres exhibit good resistant to sunlight and it also resists abrasion very well. Soaps, synthetic detergents and other laundry aids do not damage it. One of the most serious faults with polyester is its oleophilic quality. It absorbs oily material easily and holds the oil tenacity.
Chemical Properties:
Effect of alkalies:
Polyester fibres have good resistance to weak alkalies high temperatures. It exhibits only moderate resistance to strong alkalies at room temperature and is degraded at elevated temperatures.
Effect of acids:
Weak acids, even at the boiling point, have no effect on polyester fibres unless the fibres are exposed for several days. Polyester fibres have good resistance to strong acids at room temperature. Prolonged exposure to boiling hydrochloric acid destroys the fibres, and 96% sulfuric acid and causes disintegration of the fibres.
Effect of solvents:
Polyester fibres are generally resistant to organic solvents. Chemicals used in cleaning and stain removal do not damage it, but hot m-cresol destroys the fibres, and certain mixtures of phenol with trichloromethane dissolve polyester fibres. Oxidizing agents and bleachers do not damage polyester fibres.
Polyester fibres have taken the major position in textiles all over the world although they have many drawbacks e.g.,

(a) low moisture regain (0.4%),

(b) the fibres has a tendency to accumulate static electricity,

(c) the cloth made up of polyester fibres picks up more soil during wear and it also difficult to clean during washing

(d) the polyester garments from pills and thus, the appearance of a garment is spoiled,

(e) the polyester fibres is flammable.

Thus, it has been suggested that surface modifications can have an effect on hand, thermal properties, permeability, and hydrophilicity.
Polyester fabrics have been widely accepted by consumers for their easy care properties, versatility and long life, In spite of such acceptance, complaints concerning their hand, thermal properties and moisture absorbency have been cited
Improved moisture absorbency of polyester fibres can be achieved by introducing hydrophilic block copolymers. However, this modification can lead to problems of longer drying time, excessive wrinkling and wet cling. In addition, penetration of water into the interior of the fibres has not been clearly shown to improve perceived comfort
Polyester fibres are susceptible to the action of bases depending on their ionic character. Ionizable bases like caustic soda, caustic potash and lime water only effect the outer surface of polyester filaments. Primary and secondary bases and ammonia, on the other hand, can diffuse into polyester fibre and attack in depth resulting in breaking of polyester chain molecules by amide formation.

Author : Bhushan Borse (Research Student) UICT, Mumbai, India

Online clothing

With the great revolution of internet, online shopping have been flourished in recent years. Though the electronic gadgets, books, games are some of the obvious choices of online customers, textile products also finds their place and its share is increasing at a rapid rate.
There are very wide options online for clothing line. The advantage of online clothes shopping is one can catch up the latest fashion pretty fast and also get to know what color or what fashion is currently in the news. The variety offered at online clothing is also great. There are lot of online clothing shops where you can find the clothes you need in no time.
The variety in terms of color, shade, garment type, clothes for girls, clothes for boys, T shirts, jeans, skirts along with clothing accessories like belts, purse, napkins, etc. is available just one click away.

Nylon Fibres

Nylon is a polyamide fiber, derived from a diamine and a dicarboxylic acid. There are very large numbers of polyamide materials available to produce nylon fibers, as a variety of diamines and dicarboxylic acids can be used as starting materials. It was the first truly synthetic fiber to be commercialized (1939). Nylon was developed in the 1930s by scientists at Du Pont, headed by an American chemist Wallace Hume Caruthers (1896-1937). The two most commonly used synthetic polyamides are nylon 66 (polyhexamethylene adiamide) and nylon 6 (Polycaprolactam, a cyclic nylon intermediate). The chemical reactions involved in the polymerization are as follows.

CLASSIFICATION OF NATURAL DYES

Based on Color
Blue Dyes: Natural indigo, sulphonated natural indigo and the flowers of the Japanese “Tsuykusa”
Red Dyes: The colour index lists 32 red natural dyes. The prominent among them are madder (Rubia tinctorum L), Manjeet (Rubia cordifolia), Brazil wood/Sappan wood (Caesalpina sappan L), Al or Morinda (Morinda citrifolia L).
Yellow Dyes: Colour index lists 28 yellow dyes. Some of the important yellow dyes are, black oak (quercus velutina), tumeric (curcuma longa), and weld
(reseda luteola) and Himalayan rhubarb (rheum emodi).

CLASSIFICATION OF NATURAL DYES

Based on chemical structure:
Indigoids: -
The dyestuff is extracted from Indigofera tinctoria, a bush of the pea family. The dye is extracted from the leaves of the plant.
Anthraquinones: -
Red dyes are based on anthraquinone structure. These dyes are characterized by good fastness to light.
Alpha napthaquinones: -
Lawsone or Henna is the most prominent member of this class. It is obtained from the leaves of Lawsonia inermis. Another similar dye is Juglone obtained from the shell of unripe walnuts.
Flavones: -
The yellow colours are derivatives of hydroxy and methoxy substituted flavones or isoflavones. Eg: - jackfruit bark
Dihydropyrans: -
These are principal colouring matters of logwood and they give dark shades on cotton, silk, and wool.
Anthocyanidins: -
This class includes carajurin, obtained from the leaves of Bignonia chica and Awabanin. It dyes silk in blue shades.
Carotenoids: -
This class includes the orange pigment carotene found in carrots. The dyes based on carotenoid structure are annatto and saffron.

lyocell tencel

Lyocell is a man-made cellulosic fiber. It is produced by solvent spinning, i.e., regenerating into fiber form out of a cellulose solution in an organic solvent. It is made up of cellulose and derived from plant sources like wood pulp. For the solution spinning of lyocell fiber the wood pulp is first dissolved at 90 to 1200 C in a solvent NMMO (N-methyl morpholine N- oxide) under normal pressure to form viscose solution. The solution thus obtained is then filtered and extruded by means of fine jet into a water bath; here the regeneration of cellulose takes place resulting in the formation of fiber. The cellulose is regenerated after passing through an air gap into spinning bath. Finally, the fiber is drawn off with appropriate stretching followed by washing, drying and winding of the fiber. With the higher spinning speeds it is possible to produce fine deniers.

Properties of lyocell/tencel

It is the strongest of all the cellulosic fibers. It has a reduction of 15% of wet strength and hence gives an edge over the others. Tenacity lies in the range of 38-42 cN/Tex.
The ratio of crystalline to amorphous area is approximately around 9:1.
they are soft and lustrous. They show good drape and fluidity.
they are highly stable at high temperature. It does not melt but starts loosing strength rapidly at 3000 C and finally gets ignited at 4200 C
Tencel is inert to most of the organic solvents.
However, it degrades in the presence of hot dilute or cold concentrated mineral acid.
Alkalies causes swelling at first (max. at 9% NaOH solution, 250C) and then ultimately disintegration

Cotton - basic information

The cotton is a cellulose fibre. The molecules of cellulose is the main substance (97%), and pectin, protein, fats are the other substances present with very less proportion in the cotton fibre. Cotton is chemically resistance. It also withstands the action of water and light for a longer time. Cotton may easily ignite so fire safety rules must be strictly observed.

The properties and structure of cotton fibres are greatly dependent on the degree of maturity of separated fibres. Cotton fibre has the shape of a tube cross-section. The unripe fibre has the shape of thin walled pipe. Unripe fibres are weak and exhibits poor dyeability. The presence of such fibres impairs cotton quality. When the degree of maturity is higher, the pipe has thicker walls, and so fibres become stronger and more flexible. They also become crimpier.

Spider silk

Du pont is working on synthetic or spider silk and in 1998 published a report about silk they had spun. they found that the molecular orientation of the synthetic silk is very much similar to that of natural silk, whereas in synthetic silk the crystal regions were larger and apart as compared with natural silk. the fibers contained only one or two main proteins that make up drag line silk. and due to these factors the synthetic fibers had lower strength. the studies of du pont does show that synthetic spider silk is a worthwhile endeavor.

Basic dyeing of cellulosics

The dye bath is set with the following recipe and then the dyeing is performed according to the process given below:


The fabric is loaded in the rota dyeing machine and then the fabric is run for 10min at a temperature of 40C, with the dye solution in the m/c. After 10 minutes pre-dissolved salt solution is added in two lots and dye bath was heated simultaneously at 2° C/min. Finally temperature of the dye bath was set at 85– 90° C and dyeing was continued at this temperature for 60min. After the completion of dyeing the exhausted dye bath was drained and dyed material was rinsed with cold water followed by soaping and washing.


Washing off Treatments After dyeing, different washing off treatments can be carried out, time - temperature profile of those after treatments are given below. All the treatments have done in a MLR of 1:20.

CR=Cold Rinse: The dyed sample after neutralization treated with cold water for 5min at a MLR of 1:30.

HR=Hot Rinse: The dyed sample treated with hot water at 70oC for 5min at a MLR of 1:30.
SB=Soap at Boil: The sample is treated with 1gpl Auxipon NP, at boil for 10min at a MLR of 1:30

Colour and colouration

Colour has been playing a dominant role in life from time immemorial. Right from the prehistoric times man has noticed the abundance of multitude of colours worn by nature. With progress in times it was realised that the colours in nature were not permanent. The process of colouration began with application of natural colouring matters to dye clothes prepared from different natural textile fibres like cotton, linen, wool, silk etc. It was soon realized that the method of extraction of natural dyes and their application were lengthy and laborious. This gave the impetus to development of synthetic dyestuffs. Colouration in textiles ranges from apparel fabrics and other end uses like carpets, furnishing fabrics, automotive textiles, military textiles and so on. Textile colouration industry is a service that alters the appearance and aesthetics of textile materials. Colourants in textile application are principally based on organic dyestuffs and pigments, with some inorganic pigments also in use. Dyestuffs are mainly used in traditional dyeing and printing of textile material. Coloured textiles are produced today on a large industrial scale. Although modern automation techniques have been introduced for colour measurement, metering of dyes and auxiliaries and automatic control of dyeing processes much human invention is still required. Fibres can only be standardized to a limited extent due to biological and environmental factors like growing of cotton, raising of sheep etc. New developments in fashion and application have required constant modification in various procedures. Goal of every dyeing is to produce coloured textile of desired shade, homogeneous depth and hue with due consideration to economy and ecology.

emulsion in textile formulation

A lot of textile auxillaries used are in the form of emulsions. Emulsions are disperse systems consisting of two (or more) mutually insoluble or sparingly soluble liquids. The liquid present in excess is termed the closed, continuous or external phase, while the liquid dispersed in it is termed the internal or dispersed phase. The preparation of an emulsion is termed emulsification and the agents used for this purpose are termed emulsifiers. Normally the emulsions which are encountered in textile industry are oil in water (o/w) and the vice versa (w/o).

To prepare eumulsion emulsifiers are required. So what is the exact role of emulsifier? The polar (hydrophilic) aqueous phase and the polar (lipophilic) lipid or oil phase of an emulsion cannot be combined stably and homogenously without additives. The surface tension at the interface between these two phases must be reduced by the addition of emulsifiers. Emulsifiers are surface active substances that reduce the surface tension between polar and apolar phases by penetrating into the interface between the oil and the water phase. This occurs because of their amphiphilic molecular structure, i.e. they consist of both hydrophilic (polar) and lipophilic (a polar) molecular regions and are thus soluble in both the hydrophilic and the lipophilic phase.
Whether a w/o or an o/w emulsion is formed depends essentially on the stability of the emulsifier layer surrounding the droplets. If a water stable emulsifier envelope is formed around the oil droplets in a system containing water, oil and emulsifier, an o/w emulsion is produced. On the other hand the formation of an oil-stable envelope around the water droplets produces a w/o emulsion. Thus emulsifying agent should show following properties,
It should be surface active and reduce surface tension to below 10 dyne/cm
It should be adsorbed quickly around the dispersed drops as nonadherent film which will prevent coalescence
impart to the droplets an adequate electric potential so that mutual repulsion occurs
It should increase the viscosity of the emulsion
It should be effective in a reasonably low concentration

be stable
be compatible with other ingredients
be non-toxic

Emulsifiers
An emulsifier consists of water-soluble hydrophilic parts and water-insoluble, oil-soluble lipophilic parts within its.When an emulsifier is added to a mixture of water and oil, the emulsifier is arranged on the interface, anchoring its hydrophilic part into water and its lipophilic part into oil.
On the interface surface of water and air and of oil and air, the hydrophilic part and the lipophilic part are adsorbed and arranged around the interface. The emulsifier reduces the interfacial tension.That is, the force to separate the oil and water is thus weakened, resulting in the easily mixing of oil and water.

Wool Fiber

The word wool was wull in Old English, wullo in Teutonic, and wlna in pre-Teutonic days. Wool is the fiber from the fleece of domesticated sheep. It is a natural, protein, multicellular, staple fiber. The fiber density of wool is 1.31 g/cm³, which tends to make wool a mecfiurn weight fiber.

The wool fiber is a crimped, fine to thick, regular fiber. Fine wools may have as many as 10 crimps per centimeter, whilst coarse wools have less than 4 crimps per 10 centimeters. As the diameter of wool fibers increases, the number of crimps per unit length increases. The number of crimps per unit length may be taken as an indication of wool fiber diameter or wool fiber fineness.

Wool fibers may vary from off-white to light cream in colour. This variation in colour is due to the disulphide bonds which seem to be able to act as chromophores. As a result the incident light may be modified to cause the reflected light to have a tinge of yellow, giving the wool fibers their off-white appearance. When the fiber is cream to dark cream in colour, this is due more to polymer degradation on the surface of the fiber. This can readily occur, as the wool polymer is chemically very sensitive to atmospheric oxygen and air pollutants.

Fibre length to breadth ratio can be critical with wool, since the short, coarse fibers spin into less attractive yarns than do those of fine wools. In general, fiber length to breadth ratio ranges from 2500:1 for the finer, shorter wools to about 7500:1 for the coarser, longer wools.

Pilling of garment

Pilling is a garment surface fault characterized by little pills of entangled fibre and clinging to the cloth surface and giving the garment an unsightly appearance. The pills are formed during wear and washing by the entanglement of loose fibre, which protrude from the fabric surface, under the influence of rubbing action. These loose fibres develop into small spherical bundles anchored to the fabric by a unbroken fibres.

Polyester, PAN, nylon etc are strong fibre and pills forms on the garment made out of these fibres accumulate more and more making garment more unsightly.

To minimize pilling tendency, higher twist factor for yarns, the brushing and cropping of fabric surface and special chemical treatments can be used. Also, increasing the filament denier can also minimize the pilling tendency of the garments.

Dye carriers

Dye carriers are accelerators that assist in the dyeing of synthetic fabrics in a shorter time at a lower temperature. They are particularly used for dyeing polyesters with disperse dyes, although they were originally developed for cellulose acetate. There are a number of carriers commonly used for polyester fibres. Some of the good dye carriers are o-phenyl phenol and it’s monochloro derivative, p-phenyl phenol, diphenyl, monomethyl naphthalene, trichlorobenzene, dimethyl terephthalate and methyl salicylate. Other dye carriers in common usage are o-dichlorobenzene, diphenyl ether, n-butyl phthalimide, chloromethoxy ethanol, methyl cresotinate, alkyl and aryl benzoates and tetralin. The dye carrier imbibes deep shades on the polyester and blended fabrics. Acrylic and nylon fibers also can be dyed using dye carriers but this approach is more expensive than the other alternatives available.
In practice, the choice of the dye carrier is governed by its general effectiveness, toxicity, economics and environmental acceptance. Some of the phenolics and chloro-derivatives are getting eliminated. In a typical operation for dyeing polyester fiber, the dye carrier suitably emulsified in water is used in both the exhaust method at atmospheric pressure as well as in high temperature beam dyeing. After dyeing, the dye carrier is removed from the fabric by an after-scouring process. Whereas dye carriers like the chlorobenzenes are used by emulsification, the phenyl phenols can be used as their water soluble sodium salts along with an acid-liberating agent like ammonium phosphate. At about 100C, the free phenol liberated forms the active carrier which is later removed by alkaline scouring. Butyl benzoate is another successful carrier for use in polyester dyeing at the boil at atmospheric pressure.
The dye carriers are generally used with a leveling agent on polyester/wool mixtures in a high temperature process. The formulations usually consist of around 70% active ingredients (one or more dye carriers), 15% leveling agent and 15% solubilising agent. Depending on the color and shade, the dye carrier used is in a variable range of 2-10% of the textile weight.

author : Laxmikant S. Jawale

Concept of pH in Dyeing

A variety of factors can influence the quality of dyeing and batch-to-batch reproducibility, but pH ranks as one of the most important factors. The pH of dye bath solution is most critical because of its effect on the dyeing cycle with respect to level and reproducible dyeing5. Even if the pH of the dye bath has been adjusted prior to the dyeing process, it may then be affected by various factors such as the absorption of acid by the fiber itself, increased alkalinity by boiling temporarily hard water and reduce alkalinity by loss of ammonia where ammonium salts are present in the bath at elevated temperatures in open-dyeing systems.

The control of pH in dyeing is ensured by three fundamentally different techniques.

A) Maintenance of a relatively high degree of acidity or alkalinity.
B) The control of pH within narrow tolerance mainly near the neutral region.
C) The gradual shifting of pH as dyeing proceeds.


Approach A is normally easiest to control and is used in the application of leveling type of acid dyes and 1:1 metal complex dyes to wool and nylon, and of the reactive, sulphur, vat dyes to cellulose. The agents traditionally used are the acids such as sulphuric, hydrochloric, formic acid, and alkalies like sodium bicarbonate and caustic soda.

Approach B needs a greater awareness of the factors that not only determine pH, but also stabilize it against interferences. Most of the dye-fibre systems requiring this approach are operated in the near neutral region (pH 4-9) and are much more sensitive to minor changes in pH. The pH of water supply may vary, or drift, during heating.

Approach C is particularly useful for non-migrating acid dye on wool and nylon. More recently, similar systems have been proposed for reactive dyes on cellulosics. In this case, pH control involves a deliberate shift of pH during processing in a consistent direction, rather than randomly.

pH control has received considerable attention in dyeing processes because of its critical role in quality assurance8,9. In dyeing, pH exhibits strong nonlinearity and time varying behavior. Some dyeing processes such as acid dyes on nylon, etc., are very dependent on pH. In dyeing process, pH not only responds to the addition of acids or base, but also varies as the temperature increases.

General Concept of pH and Buffer

pH

Pure water contains, in addition to H₂O molecules, a very small proportion of electrically charged ions formed by electrolytic dissociation, according to the equation

Where H ⁺ is a hydrogen ion, hydrion or proton, produced from a hydrogen atom by the loss of an electron and hence carrying positive charge; and OH ^- is a hydroxyl ion, which is negatively charged.

In pure water the two ions are present in equal numbers, since the water is electrically neutral, and at 25⁰C. their concentration is 10^-7 gm-ions per litre. It can be shown (from the law of mass action) that, in any dilute aqueous solution, the product of concentrations of the hydrogen ions and hydroxyl ions is constant and is equal to 10^-14 gm-ions per litre. i.e.,

[H ⁺] X [OH ^-] = 1.0 X 10^-14

When an acid is added to water it introduces hydrogen ions. Hydrochloric acid, for example, introduces hydrogen ions and chloride ions through electrolytic dissociation

Consequently, hydroxyl ions in the water are reduced so that the product of the hydrogen ion concentration and hydroxyl ion concentration remains equal to 10^-14. For example, if the concentrations of hydrogen ions is increased to 10^-3, the concentration of hydroxyl ions must fall to 10^-11. Similarly, alkalies such as caustic soda introduce hydroxyl ions.

and so cause a reduction in the number of hydrogen ions present in the water. Solutions are acid when the number of hydrogen ions exceeds the number of hydroxyl ions, and alkaline when the hydroxyl ions are in excess of the hydrogen ions. The degree of acidity or alkalinity depends entirely on the relative proportions of the two ions.

In pure water at 25⁰C, the hydrogen ion concentration (H ⁺) = 10^-7gm-ions per litre, or –log₁₀ (H⁺) = 7. The pH value of water is therefore 7, the relation between pH and hydrogen ion concentration being expressed by the equation –

i.e., the pH value is equal to the logarithm of the hydrogen ion concentration with negative sign.

plasma

Plasma is so called fourth state of matter, the other three ordinary states being solid, liquid and gaseous and by scientists as the ‘ionized state’. Thus plasma state of matter was used by the industry for almost one century before being christened.

What is plasma?

Any matter in its gaseous, liquid or solid state can be transformed into its plasma state by applying an external stimulus, if it is held within a suitable container.
The electrons in the outermost orbit of the atoms making up the gas, liquid or solid matter gets knocked off and thus a mixture of electrons and ions or the atomic nuclei exists. The ordinary atoms of matter do not have any electrical charge nor do they conduct electrical currents. The ability to conduct electricity is one fundamental difference between an ordinary state of matter and the plasma state.
Electrical energy initiated cold plasma states arise when free electrons of a low pressure gas or gaseous mixture are accelerated by electrical or electromagnetic fields to a kinetic energy level at which ionization, excitation and molecular fragmentation processes are generated by an electromagnetic radiation. This state of the matter is characterized y the simultaneous presence of electrons, ions and either polarity, neutral atoms and gas molecules. It also can be noticed that the 0-5eV energy spectrum of cold plasmas are intense enough to cleave almost all chemical bonds involved in organic structure and to create active molecular fragments. (e.g., free radicals). Relatively higher energies are required only by the dissociation of double bonds and by the formation of corrosponding free radicals. As a consequence, all organic and elemental organic derivatives can easily be modified and converted into macromolecular structures which limit the plasma states through the recombination of plasma generation active molecular fragments. It also can be understood why higher energies of active species of plasmas will generate macromolecular structures based on unsaturated bonds and three dimensional networks. (Cross linked structures).
The modification of the chemical structure reactivity and bonding characteristics of polymer surfaces has considerable technological importance in the areas of metallization, composite fabrication and biomedical compatibility. Plasma treatment is one type of surface modification that is commonly used. A unique feature of plasma modification is that the surface structure of the polymer can be selectively modified for a specific application while the bulk properties of the polymer are unaffected. The surface specificity of plasma modification makes it difficult to elucidate the nature of the chemical changes with conventional techniques. Also the complexity of the plasma itself makes it difficult to unravel the mechanism responsible for the surface modifications.
Low temperature plasma treatment is a useful technique to modify a polymer surface and leads to polymerization, grafting, cross linking of chemical incorporation. Free radicals generated in the treatment play an important role in these reactions and it is likely that some of unstable free radicals combine rapidly and some of stable free radicals remain in the polymer matrix as living radicals.

Desizing
The treatment of cloth containing PVA size with low temperature plasma has been suggested as a pretreatment to desizing. The PVA was degraded by the O2 in the air to carbon dioxide and water during plasma exposure. Adverse effects on fabric properties were not observed. Upto 95% of the PVA can be oxidized in this manner. Costs of the process are not available and no useful products can be recovered.

Water repellency and surface modification of PET
PET fabrics have also been successfully treated with O2 or CF4 plasma under different power pressure and time conditions. Oxygen plasma treatment improved both water uptake and surface disability while CF4 plasma treatment improves water repellency along with improved surface dyeability.

Effects of plasma
Improves wettability
Induced chemical reactivity of fibre surface
Induced hydrophobic properties
Fibre surface cleaning

Advantages
No water required
Small amount of chemical needed
No waste production
Confined to fibre surface
Energy efficient
Special textile properties can only be obtained via plasma processing

Industrial Conquerors

Industrial Conquerors

The spectrum of application of the textile fibres has been broadened with the advent of areas like Geo – Textiles, Industry, and Building – construction, Medical field, Automotives, Agriculture, Sports, Clothing, and Packaging have widened the reign of textile fibres-The Emperors of Industry. This paper discusses the properties of the textile fibres, which are necessary for their application in the industry as technical textile. Some of the most widely used textile fibres are reviewed in brief. The application of the textile fibres in various fields in the industry has made them the conquerors in the technical textile sector. The industrial applications of the textile fibres include reinforcements in the tires, and plastics, electrical insulations, industrial ropes, coated fabrics, filtration fabrics, etc. The paper puts light on each of these applications in brief. Various fibres used for the reinforcement in the tire have also been discussed. However, the cost of these fibres has confined their applications so there is an urgent need of developments in this field to develop novel processes, which can reduce the cost of production of the fibres, so the application can be extended further.