NATURAL DYEING OF TEXTILES

Introduction
Dyeing is an ancient art which predates written records. It was practised during the Bronze age in Europe. Primitive dyeing techniques included sticking plants to fabric or rubbing crushed pigments into cloth. The methods became more sophisticated with time and techniques using natural dyes from crushed fruits, berries and other plants, which were boiled into the fabric and gave light and water fastness (resistance), were developed.
Some of the well known ancient dyes include madder, a red dye made from the roots of the Rubia tinctorum, blue indigo from the leaves of Indigofera tinctoria, yellow from the stigmas of the saffron plant, and dogwood, an extract of pulp of the dogwood tree. The first use of the blue dye, woad, beloved by the Ancient Britons, may have originated in Palestine where it was found growing wild. The most famous and highly prized colour through the age was Tyrian purple, noted in the Bible, a dye obtained from the spiny dye-murex shellfish. The Phoenicians prepared it until the seventh century, when Arab conquerors destroyed their dyeing installations in the Levant. A bright red called cochineal was obtained from an insect native to Mexico. All these produced high-quality dark colours. Until the mid-19th century all dyestuffs were made from natural materials, mainly vegetable and animal matter.
Today, dyeing is a complex, specialised science. Nearly all dyestuffs are now produced from synthetic compounds. This means that costs have been greatly reduced and certain application and wear characteristics have been greatly enhanced. But many practitioners of the craft of natural dying (i.e. using naturally occurring sources of dye) maintain that natural dyes have a far superior aesthetic quality which is much more pleasing to the eye. On the other hand, many commercial practitioners feel that natural dyes are non-viable on grounds of both quality and economics. In the West, natural dyeing is now practised only as a handcraft, synthetic dyes being used in all commercial applications. Some craft spinners, weavers, and knitters use natural dyes as a particular feature of their work.
In many of the world’s developing countries, however, natural dyes can offer not only a rich and varied source of dyestuff, but also the possibility of an income through sustainable harvest and sale of these dye plants. Many dyes are available from tree waste or can be easily grown in market gardens. In areas where synthetic dyes, mordants (fixatives) and other additives are imported and therefore relatively expensive, natural dyes can offer an attractive alternative.


Dyeing of textiles Practical Action


The knowledge required for sourcing and extracting such dyes and mordants is, however, often not available as extensive research work is required to identify suitable plants, minerals, etc. In Zambia for example, there is a wealth of plants available for producing
natural dyes, but due to lack of knowledge of the processes involved in harvesting and processing the plants, little use is made of this natural resource. In some countries, such as India, Nigeria and Liberia, where this research has been carried out, or where there exists a tradition of natural dyeing, natural dyes and mordants are used widely.
Types of textiles suitable for dying
Natural dyes can be used on most types of material or fibre but the level of success in terms of fastness and clarity of colour varies considerably. Users of natural dyes, however, tend to also use natural fibres, and so we will look in more detail at this group. Natural fibres come mainly from two distinct origins, animal origin or vegetable origin. Fibres from an animal origin include wool, silk, mohair and alpaca, as well as some others which are less well known. All animal fibres are based on proteins. Natural dyes have a strong affinity to fibres of animal origin, especially wool, silk and mohair and the results with these fibres are usually good. Fibres of plant origin include cotton, flax or linen, ramie, jute, hemp and many others. Plant fibres have cellulose as their basic ingredient. Natural dyeing of certain plant based textiles can be less successful than their animal equivalent. Different mordanting techniques are called for with each category. When a blend of fibre of both animal and plant origin is being dyed, then a recipe should be chosen which will accentuate the fibre which is required to be dominant.
Equipment needed for home dyeing and very small-scale commercial dyeing
Most equipment needed for dyeing fabrics at home, or at the very small-scale commercial level, can be found in almost any market place throughout the world. The following is a list of the equipment requirements and a brief explanation of their use.

1.    • Heat source. This can be any type of cooking stove; gas, wood, kerosene, charcoal, electricity. This is used for heating the liquid used during mordanting and dyeing.

2.    • Pestle and mortar. Used for milling the natural dye or minerals, where this is called for.

3.    • Mordanting and dyeing pans. Stainless steel or enamel pans are the most suitable for dyeing. The size of pan depends upon the quantities of fabric that will be dyed. Do not use pans made from copper, aluminium or iron, unless absolutely necessary, as these metals have properties which can change the colour of the dye.

4.    • tirring rods. Stainless steel or glass rods are best as they can be cleaned and used for different colour dyes. If wooden stirring rods are used then there should be a different spoon for each colour.

5.    • Thermometer. This is used to measure the temperature of the liquid during mordanting and dyeing. A long thermometer (to reach the liquid at the bottom of the pan) is preferred, with a range of 0 – 100oC (32 – 210oF).

6.    • Measuring jugs. These are used to measure the quantities of liquid called for in the recipe. Sometimes precise quantities are called for.

7.    • Storage containers. Used for storing the dyestuffs and mordants. Large glass and plastic jars are ideal. Some mordants and dyes are sensitive to light and should therefore be stored in sealed light-proof containers.

8.    • Plastic bowls and buckets. A variety of plastic bowls or buckets of varying sizes are useful when wetting or rinsing fabrics.

9.    • Strainer. Used for straining the liquid off the dyestuff in the dyebath.

10.                       • Weighing scales. Used for obtaining the correct quantities as specified in the recipe. A scales with metric and imperial measurement is useful as conversions from one system to the other are not then needed.

11.                       • Protective equipment. Gloves for holding hot pans will prevent burns. An apron will protect your clothing. Rubber gloves will prevent skin irritation caused by mordants, and

2 Dyeing of textiles Practical Action

1.    will also prevent you from dyeing your hands. A face mask can cut down the amount of fumes or powder inhaled during the dyeing process.

Mordants
Few natural dyes are colour-fast with fibres. Mordants are substances which are used to fix a dye to the fibres. They also improve the take-up quality of the fabric and help improve colour and light-fastness. The term is derived from the Latin mordere, to bite. Some natural dyes, indigo for example, will fix without the aid of a mordant; these dyes are known as ‘substantive dyes’. Others dyes, such as madder and weld, have a limited fastness and the colour will fade with washing and exposure to light.
Traditionally, mordants were found in nature. Wood ash or stale urine may have been used as an alkali mordant, and acids could be found in acidic fruits or rhubarb leaves (which contain oxalic acid), for example. Nowadays most natural dyers use chemical mordants such as alum, copper sulphate, iron or chrome (there are concerns, however about the toxic nature of chrome and some practitioners recommend that it is not used).
Mordants are prepared in solution, often with the addition of an ‘assistant’ which improves the fixing of the mordant to the yarn or fibre. The most commonly used mordant is alum, which is usually used with cream of tartar as an additive or assistant. Other mordants are:

1.    • Iron (ferrous sulphate)

2.    • Tin (stannous chloride)

3.    • Chrome (bichromate of potash)

4.    • Copper sulphate

5.    • Tannic acid

6.    • Oxalic acid

Using a different mordant with the same dyestuff can produce different shades, for example;

1.    • Iron is used as a ‘saddener’ and is used to darken colours.

2.    • Copper sulphate also darkens but can give shades which are otherwise very difficult to obtain.

3.    • Tin brightens colours.

4.    • Tannic acid, used traditionally with other mordants, will add brilliancy.

5.    • Chrome is good for obtaining yellows.

6.    • Oxalic acid is good for extracting blues from berries.

7.    • Cream of Tartar is not really a mordant but is used to give a lustre to wool.

Mordants are often poisonous, and in the dye-house they should be kept on a high shelf out of the reach of children. Always use protective clothing when working with mordants and avoid breathing the fumes.
The mordant can be added before, during or after the dyeing stage, although most recipes call for mordanting to take place prior to dyeing. It is best to follow the instructions given in the recipe being used or experiment on a sample before carrying out the final dyeing. Later in this brief we will explain how the mordant is mixed and used as part of the dyeing process.
These chemical mordants are usually obtained from specialist suppliers or from chemists. Where this is prohibitive, due to location or cost, natural mordants can be used. There are
3 Dyeing of textiles Practical Action
a number of plants and minerals which will yield a suitable mordant, but their availability will be dependent upon your surroundings. Some common substitutes for a selection of mordants are listed below.

1.    • Some plants, such as mosses and tea, contain a small amount of aluminium. This can be used as a substitute to alum. It is difficult to know, however, how much aluminium will be present and experimentation may be necessary.

2.    • Iron water can be used as a substitute to ferrous sulphate. This can be made simply by adding some rusty nails and a cupful of vinegar to a bucket-full of water and allowing the mixture to sit for a couple of weeks.

3.    • Oak galls or sumach leaves can be used a substitute to tannic acid.

4.    • Rhubarb leaves contain oxalic acid.

Natural dyestuffs
Dyestuffs and dyeing are as old as textiles themselves. Nature provides a wealth of plants which will yield their colour for the purpose of dyeing, many having been used since antiquity. In this section we will look at some of these naturally occurring dyes, their source and the colours they produce. Later in the brief we will look at the application of the dyes to textiles.
Almost any organic material will produce a colour when boiled in a dye-bath, but only certain plants will yield a colour that will act as a dye. The plants given in Table 1 are a selection of plants that have stood the test of time, and are used widely and traditionally by natural dyers. Natural dyes fall into the following categories:

1.    • Leaves and stems

2.    • Twigs and prunings

3.    • Flower heads

4.    • Barks

5.    • Roots

6.    • Outer skins, hulls and husks

7.    • Heartwoods and wood shavings

8.    • Berries and seeds

9.    • Lichens

10.                       • Insect dyes

Figure 2: Marigold

Common Name	Latin Name	Parts Used	General Colour Guide	Suggested Mordant
Alder	Alnus spp	Bark	Yellow/ brown/ black	Alum, iron. Copper sulphate
Alkanet	Anchusa tinctoria	Root	Grey	Alum, cream of tartar
Apple	Malus spp	Bark	Yellow	Alum
Blackberry	Rubus spp	Berries, young	Pink,	Alum, tin

4 Dyeing of textiles Practical Action

shoots				Purple
Betel nut		Areca catechu		Nut		Deep pink
Blackwillow	Salix negra		Bark		Red, brown		Iron
Bloodroot	Sanguinaria canadensis		Roots		Red		Alum, tin
Buckthorn	Rhammus cathartica		Twigs, berries, bark		Yellow, brown		Alum, cream of tartar, tin, iron
Cherry (wild)	Prunus spp		Bark		Pink, yellow, brown		Alum
Dahlia	Dahlia spp		Petals		Yellow bronze		Alum
Dog’s mercury	Mercurialis perennis		Whole plant		Yellow		Alum
Dyer’s broom	Genista tinctoria		Flowering tops		Yellow		Alum
Elder	Sambucus negra		Leaves, berreis, bark		Yellow, grey		Iron, alum
Eucalyptus		Eucalyptus		Leaves		Deep gold, grey
Fustic		Chloropho-ria tinctoria		Wood shavings		Yellow
Groundnut	Arachis hypogea		Kernel skins		Purple, brown, pink		Copper sulphate, alum
Henna		Lawsonia inermis		Leaves		Gold
Hypogymnia lichen		Hypogymnia psychodes		Whole lichen		Gold, brown
Indigo	Indigofera		Leaves		Blue		Not required
Ivy	Hedera helix		Berries		Yellow, green		Alum, tin
Madder	Rubia tinctora		Whole plant		Orange, red		Alum, tin
Maple	Acer spp		Bark		Tan		Copper sulphate
Marigold	Calendual spp		Whole plant, flower heads		Yellow		Alum
Nettles	Urtica dioica		Leaves		Beige, yellowy greens		Alum, copper
Onion	Allium cepa		Skins		Yellow, orange		Alum
Oak	Quercus spp		Inner bark		Gold, brown		Alum
Ochrolech-ina lichen	Ochrolech-ina parella		Whole lichen		Orange, red (when fermanted in urine then boiled)		Alum
Privet	Ligustrum vulgare		Leaves, berries		Yellow, green, red, purple		Alum, tin
Ragwort		Senecio		Flowers		Deep yellow
Safflower	Carthamus tinctoria		Petals		Yellow, red		Alum
Sloe- Blackthorn	Prunus spinosa		Sloe berries, bark		Red, pink, brown		Alum
Tea		Camelia sinensis		Leaves		Beige
Turmeric		Circuma longa		Root		Yellow
Wild mangosteen		Diospyros peregrina		Fruit		Grey, pink
Weld (wild mignonette)	Reseda luteula		Whole plant		Olive green		Alum, cream of tartar
Woad	Isatis tinctoria		Whole plant		Blue		Lime

Table 1. A list of plants commonly used for preparing dyes.
The choice of mordant for a particular plant is dependant upon the material with which it will be used. It is necessary to check a recipe before using a plant, or one can experiment to see what effect a mordant has for a particular application.
It is recommended that plants be grown specifically for the purpose of dyeing. Harvesting plants from the wild on a non-sustainable basis can endanger the survival of the plant. Many lichens are registered as protected organisms and it is illegal to gather them from the wild. 

Fiber to Fabric

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Nylon Fiber

1. INTRODUCTION

Nylon 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). It is a polyamide fiber, derived from a diamine and a dicarboxylic acid, because a variety of diamines and dicarboxylic acids can be produced, there are a very large number of polyamide materials available to produce nylon fibers. The two most common versions are nylon 66 (polyhexamethylene adiamide) and nylon 6 (Polycaprolactam, a cyclic nylon intermediate). Raw materials for these are variable and sources used commercially are benzene (from coke production or oil refining), furfural (from oat hulls or corn cobs) or 1,4-butadiene (from oil refining).

            2. FIBER TYPES

Fiber types are produced commercially in various parts of the world. Nylon 66 has been preferred in North American markets, whereas nylon 6 is much more popular in Europe and elsewhere. Nylon is produced by melt spinning and is available in staple, tow, monofilament, and multi-filament form. The fiber has outstanding durability and excellent physical properties. Nylons are semi-crystalline polymers. The amide group -(-CO-NH-)- provides hydrogen bonding between polyamide chains, giving nylon high strength at elevated temperatures, toughness at low temperatures, combined with its other properties, such as stiffness, wear and abrasion resistance, low friction coefficient and good chemical resistance. These properties have made nylons the strongest of all man-made fibers in common use. Because nylons offer good mechanical and thermal properties, they are also a very important engineering thermoplastic. For example, 35% of total nylon produced is used in the automobile industry [2]. There are several commercial nylon products, such as nylon 6, 11, 12, 6/6, 6/10, 6/12, and so on. Of these, the most widely used nylon products in the textile industry are formed of nylon 6 and nylon 6/6. The others are mainly used in tubing extrusion, injection molding, and coatings of metal objects [3].

Nylon's outstanding characteristic in the textile industry is its versatility. It can be made strong enough to stand up under the punishment tire cords must endure, fine enough for sheer, high fashion hosiery, and light enough for parachute cloth and backpacker's tents. Nylon is used both alone and in blends with other fibers, where its chief contributions are strength and abrasion resistance. Nylon washes easily, dries quickly, needs little pressing, and holds its shape well since it neither shrinks nor stretches.

3. FIBER FORMATION

One of the most important factors in polymer processing is viscosity, which is a function of molecular weight. The number-average molecular weight of polymer suitable for textile fiber production ranges from 14,000 to 20,000. Since Polycaprolactam can be regarded at equilibrium as a polycondensation polymer, the number-average molecular weight alone is sufficient for its characterization. Two-step melt spinning, comprised of spinning and drawing, is considered to be the conventional method to manufacture nylon filaments. After melting, filtering, and deaerating, the molten polymer is extruded through a spinneret into a chamber where the melt solidifies into a filament form. At this stage, the filaments have little molecular orientation, and their slight birefringence is due to shear forces set up during extrusion. In order to achieve desirable properties through molecular orientation and crystallinity, the newly formed filaments must be drawn. Since the Tg of nylon is below room temperature, nylon can be cold drawn.Hot drawing is also frequently used. Nylon filaments are drawn approximately four times their initial length. The effect of drawing on birefringence, a measure of molecular anisotropy, can be seen in Table I. Also, the elastic modulus increases significantly with increasing orientation as shown in Table I. Other physical properties, such as density equilibrium, moisture sorption, tenacity and elongation-at-break, are also affected by drawing.

Table 1: Effect of Drawing on Birefringence and Elastic modulus

Draw Ratio	Birefringence	Elastic Modulus (GPa)
1	0.00832	1.97
2	0.03297	2.74
3	0.05523	3.70
4	0.05904	4.59
5	0.06381	5.77
60	0.06901	6.74

Rather than two-step spinning (extrusion) and drawing, a one-step, high-speed spinning process is being used increasingly. In high-speed spinning, filament windup speed relative to the extrusion speed is very high and orientation and crystallization occur in elongation flow along the spin line. When drawing as-spun fibers, the molecules are arranged randomly in amorphous regions and as folded chains in crystalline region .

In essence, cold drawing stretches chains in amorphous regions, but molecular folds are restricted and the molecules orient themselves along the fiber axis direction, resulting in enhanced orientation and high crystallinity. In the case of nylons, which have sheet-like crystal structures, drawing may enable the hydrogen-bonded polyamide sheets to slip past each other and form more oriented structure [4]. Hot drawing is a procedure using high temperature during drawing and annealing under restraint after drawing. Exposure to high temperature helps to increase the draw ratio, and higher moduli and tenacity can be achieved.. Ultra drawing of solidified crystalline material induces a high degree of chain extension, which leads to very high tensile strength and modulus. This results in a so-called high-performance fiber.A skin-core structure, mostly depending on spinning speed, is generally formed within melt-spun fibers. At a constant feeding rate, higher spinning speeds will produce more extended chains in the melt and form a finer filament. Therefore, the finer fiber usually has higher modulus and tenacity. Fine filament cannot be drawn as much as a coarse filament, because partial orientation on the outer parts of the filaments is formed when the molten fluid is drawn over the sides of the orifice. As a result, finer filaments have a greater proportion of 'skin' to bulk, i.e., better orientation has already been formed. Naturally, there is not much space for an improvement by cold drawing within fine filaments. The filaments become lustrous and strong.

4. RHEOLOGICAL BEHAVIOR

The melt viscosity of the polymer can be represented as a function of molecular weight by the relationship [5, 6]:

η=K (M_w) ^a

Where is the zero shear viscosity, M_w it the weight average molecular weight, K and an are constants dependent upon the polymer and temperature. In the case of nylons, the value of exponent a normally is in the range of 3.4-3.8.

It has long been known that moisture has a strong effect on the rheological behavior of nylons. Generally, high moisture levels cause degradation and foaming, and relatively low levels of moisture act as plasticizer in nylon 6 during melt processing. All nylons absorb moisture. The extent of moisture absorption depends on temperature, crystallinity, and humidity. Therefore, before processing of nylon resins, the polymer pellets must be dried to moisture levels below 0.2 wt%, in order to avoid bubble formation and significant polymer degradation during processing. A recent study [7] found that the drying temperatures used affect zero shear melt viscosity. The result is shown in

Table 2. Effect of Resin Drying Temperature on Zero Melt Viscosity

Drying Temperature (°C)*	Molecular Weight Exponent
50	3.8
110	4.6-5.4

5. NON-CONVENTIONAL SPINNING TECHNIQUES

Alternative to conventional melt spinning, various solution-spinning techniques have been introduced [8,9]. Solution spinning techniques (gel, wet, dry) enable the spinning of high molecular weight polyamides, leading to high tenacity filaments (tenacity 100cN/tex)[8]. As an innovation on fiber formation, new technologies producing micro fibers have been developed and reported [10]. Primarily direct spinning and mechanical and solvent splitting produce micro fibers. Electro spinning [11] represents another approach to fiber spinning, when electrical forces on polymer melt or solution surface overcome the surface tension and cause an ejection from an electrically charged jet. The diameter of the fibers produced by this technique is of the order of nanometers. Frequently, there are produced fibers that are electrically charged.

6. CRYSTALLINE STRUCTURE

Both nylon 6 and nylon 66 are semi-crystalline polymers. These linear aliphatic polyamides are able to crystallize mostly because of strong intermolecular hydrogen bonds through the amide groups (Figure. 3)[3], and because of Vander walls forces between the methylene chains. Since these unique structural and thermo-mechanical properties of nylons are dominated by the hydrogen bonds in these polyamides, quantum chemistry can be used to determine the hydrogen bond potential [3]. The left side of the figure shows hydrogen-bonding planes, and the right side shows the view down the chain axis. For the -form of nylon 6, adjacent chains are ant parallel and the hydrogen bonding is between adjacent chains within the same sheet (bisecting the CH₂ angles). For the -form of nylon 6, the chains are parallel and the hydrogen bonding is between chains in adjacent sheets. . In nylon 66, the chains have no directions.

Mechanical, thermal and optical properties of fibers are strongly affected by orientation and crystallinity. Basically, higher fiber orientation and crystallinity will produce better properties. Crystallinity of nylons can be controlled by nucleation, i.e., seeding the molten polymer to produce uniform sized smaller spherulites. This results in increased tensile yield strength, flexural modulus, creep resistance, and hardness, but some loss in elongation and impact resistance. Another important benefit obtained from nucleation is decrease of setup time during processing [1].

7. DYEABILITY

The dyeing efficiency of nylon fibers is enhanced due to the end groups -COOH and -NH2, which exhibit polar and hydrophilic characteristics. Dye diffusion into fibers is closely related to the rate of dyeing, level of dyeing through dye migration, wet fastness properties of dyes, etc. It is generally believed that dye diffusivity is independent on dye concentration, with some exception. T. Shibusawa [12] studied the diffusion of most disperse dyes on nylon 6 and found that the actual diffusivity on nylon 6 fibers is not always independent on dye concentration. Kim et al. [13] have reported that both dyeing rate and dye saturation of 1,4 -diaminoanthraquinone (1,4-DAA) were improved considerably in the presence of didodecyldimethlammonium bromide (DDDMAB). The amount of DDDMAB adsorbed on nylon 6 fiber is roughly 20 times higher than that a conventional dispersing agent. This suggests that there might be fairly strong interaction between DDDMAB and the fiber by virtue of electrostatic and hydrophobic interactions. There have been many attempts to improve nylon's dyeability or at least to point out the factors and mechanisms acting in nylon dyeing. It has been shown that acrylonitrile and styrene radiation grafting on the polymer could improve the dyeability of nylon [15]. Another approach to higher dyeability of nylon 6 is by copolymerization [16]. In this case, the dyeability can be improved at the expense of a decrease of specific viscosity and of heat and hydrolysis resistance. Other treatments, such as plasma etching [17] and superheated steaming [18] have proved to decrease nylon dyeability. In the former treatment, outer structures, not normally susceptible to dyes, are etched away whereas the crystalline phases inside the fiber are not as much affected. Superheated steaming of the fibers leads to higher shrinkage and to higher crystallinity and crystal size, which contribute to decrease dyeability.

8. DEGRADATION

The -COOH and -NH₂ end-groups in nylons are sensitive to light, heat, oxygen, acids and alkali. When exposed to elevated temperatures, unmodified nylons undergo molecular weigh degradation, which results in loss of mechanical properties. The degradation is highly time/temperature dependent. By adding heat stabilizer, nylon can be used at elevated temperature for long-term performance. Exposure to UV light results in degradation nylon over an extended period of time, it appears that adding carbon black can reduce the radiation degradation. Nylons are chemical resistance to hydrocarbons, aromatic and strong acids, bases, and phenols attack aliphatic solvents, but them. They also are gradually attacked hydrolytically by hot water. Newly developed sulfonation of nylon 6 fiber [19] by 2,5 dichlorobenzene sulfonyl chloride (DSBC) has a great effect on the heat and chemical stability of the fibers. It reported that the modified fiber is non-melting up to 1000^oC, and does not burn when put it in direct flame (but chars without losing fiber form). It does not dissolve in formic acid and concentrated mineral acid. Its glass transition temperature is about 500^oC.

9. PROPERTIES OF NYLON 66

-Tenacity-elongation at break ranges from 8.8g/d-18% to 4.3 g/d-45%. Its tensile strength is higher than that of wool, silk, rayon, or cotton.

- 100% elastic under 8% of extension

-Specific gravity of 1.14

-Melting point of 263^oC

-Extremely chemically stable

-No mildew or bacterial effects

-4 - 4.5% of moisture regain

-Degraded by light as natural fibers

-Permanent set by heat and steam

-Abrasion resistant

-Lustrous- Nylon fibers have the luster of silk

-Easy to wash

-Can be pre colored or dyed in wide range of colors; dyes are applied to the molten mass of nylon or to the yarn or finished fabric.

-Resilient

-Filament yarn provides smooth, soft, long lasting fabrics

-Spun yarn lend fabrics light weight and warmth

10. PROPERTIES OF NYLON 6

The main difference between nylon 6 and nylon 6,6 is nylon 6 has a much lower melting point than nylon 66. This is a serious disadvantage, as garments made from it must be ironed with considerable care.

11. NONWOVENS USAGE

The fiber has outstanding durability and excellent physical properties. Like PET fiber, it has a high melting point, which conveys good high- temperature performance. The fiber is more water sensitive than PET; despite this fact, nylon is not considered a comfortable fiber in contact with the skin. Its toughness makes it a major fiber of choice in carpets, including needle punched floor-covering products. Because of its relatively high cost, nylon has somewhat limited use in nonwoven products. It is used as a blending fiber in some cases, because it conveys excellent tear strength. The resiliency and wrinkle recovery performance of a nonwoven produced from nylon is not as excellent as that from PET fiber.

12. WORLD CONSUMPTION OF NYLON FIBER IN NONWOVENS 1998- 2007

It is forecasted that global consumption of nonwoven may reach 3.7 million tons by 2005 and 4 million tones by 2007.Consumption of manmade fiber was about 8.1% of all Textile fibers in 1998.In 2005 it is expected to reach 10% and 10.4 % by 2007.In certain applications, the performance of nylon fiber is hard to beat. However, because of its higher cost, it is used in specialized applications where its performance can justify the increased cost. It is used as a blending fiber in some cases, because it conveys excellent tear strength. The resiliency and wrinkle recovery performance of a nonwoven produced from nylon is not as excellent as that from PET fiber. This polymer is used in moderate quantities, because it is more expensive than polyester, polypropylene, or rayon. Some particular applications are as follows:

·         It can be mostly found in garment interlinings and wipes where it supplies strength and resilience.

·         In Ni/H and Ni/Cd batteries, nylon fibers are used as Nonwovens separators.

·         Nylon fibers are used for the manufacture of split table-pie fibers. These fibers find application in high performance wipes, synthetic suede, heat insulators, battery separators and specialty papers.

·         Nonwovens developed from nylon are found in automotive products, athletic wear and conveyor belts.

REFERENCES

[1]. P. G. Galanty, and G. A. Bujtas, “Modern Plastics Encyclopedia” '92, pp 23-30 McGraw Hill 1992

[2]. P. Meplestor, “Modern Plastics”, 74, Jan., 66 (1997)

[3]. S. Dasgupta, W.B.hammond, and W.A. Goddard III, J. Am. Chem. Soc. 118,12291-12301, (1996)

[4] A. B. Thompson Fiber structure Edited by J. W. Hearle and R. H. Peters, Butterworth & Co. Ltd. and the Textile Institute pp 499 (1963)

Colour

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Tea fiber

Tea fiber is a kind of new fiber developed by Qingdao Meidu Textile Co., Ltd.. It is high-end functional fiber firstly developed at home and abroad, and reaches the international advanced level. It is antibacterial and odor resistant viscose fiber made from natural tea pigment, tea polyphenols and catechins which are extracted from tea.
Tea fiber is natually antibacterial, odor resistant, moisture absorption and breathable. The bacteriostasis rate and bactericidal rate on staphylococcus aureus and escherichia coli have reached or exceeded the standard of China, US and Japan.
The natural green tea antimicrobial agent uniformly distributes in the tea fiber, thus it can improve the microcirculation of human body after the long-term contact with skin. The textile products made by the fiber are anti-radiation and anti-ultraviolet.
Tea fiber and its products are naturally toasted almond colored, which will not cause pollution and are harmless to human body.
Tea fiber is believed to have a bright future