Dyeing shade matching

CHEMISTRY OF FIBRE

It deals with the source, structure, composition, and properties of different kinds of Textile Fibres.

SOURCE (AVAILABILITY)

Fibres are obtained from different sources. To keep control over the commercial value, the textile Fibres must be available in large quantities and its supply more or less constant and low in price.

Examples: -

1.Cotton Fibre from Cotton plant

2.Coir Fibre from coconut husk.

Cellulose Fibres

3.Wool from sheep

Protein fibres

4.Silk from Silkworm

5.Terylene

Man-made fibres

6. Nylon

DIFFERENT TYPES OF FIBRES

Natural or Artificial (man-made) fibrous materials are used for the manufacture of textile goods.

1. Cellulose Fibre

2. Protein Fibre

Natural fibres

3. Regenerated Fibre - Man-made Fibre

STRUCTURE

There are many Fibre structures in nature. The word Fibre means fine strand which is several hundred times longer than its width, but it is only those that can be spun into yarn suitable for weaving or knitting that is classified as. Textile Fibres.

Uses

The finished Textile products can be used for Apparel and Industrial purposes. The properties of Fibres will decide the qualities and uses. During use, the products are subjected to several physical treatments like stretching, pressing, twisting, squeezing, rubbing, etc., and chemical treatments with acids, alkalis, oxidizing and reducing agents, temperature, washing, etc.

APPAREL USES

INDUSTRIAL USES

Clothing's

'V' Belts

Furnishings

Tire cords

Tarpaulin

 PROPERTIES

Textile product has to withstand the properties during use and to fulfill the demands of the customers. The physical and chemical properties of the products decide the quality and end-use. So, it is essential to know about the properties of Fibre, the effect of finishes, the type of construction, and its uses.

The value of Fibre for textile purposes is determined by the degree to which it possesses certain fundamental properties such as staple length, tensile strength, elasticity, spinnability, flexibility. etc. to spin into yarn and make into fabric.

ESSENTIAL PROPERTIES

1. Staple length

Staple length is the most important property necessary to convert the Fibre into continuous length and it determines the usefulness. It is important to note that the strength of the thread is directly proportional to the length of individual Fibre used in the manufacture of that thread. The staple length of natural Fibre varies in length. Hence proper selection and grading of fibre is necessary to produce a particular type of yarn.

2. Tensile strength

Tensile strength is the most important property required for a textile Fibre. If the individual Fibre does not have strength, it is not possible to make a yarn from it. Although dependent on other qualities, the primary property essential is the tensile strength of Fibre to resist wear and tear while in use.

3. Spinnability (Cohesiveness)

The third essential quality required for a textile Fibre is the spinning power. It is the property of the individual Fibres holding one another when spun into yarn. Cohesiveness is the frictional resistance caused by the irregular surface of the Fibres. Cotton, coir, and wool possess an irregular surface that gives a high degree of friction and this is greatly increased by giving a twist in Fibre which interlocks several Fibres spun together and thus prevents the Fibres from slipping when subjected to strain.

4. Fineness

Fineness is the thickness of a Fibre and is expressed by its diameter in microns. It will decide the quality of the yarn or product. The finer the staple of the Fibre, the finer will be the yarn produced from it.

5. Elasticity

It is one of the most important properties of textile Fibre. It decides the breaking strength of the Fibre or yarn. The durability of a Fibre also determines in great measure its elasticity.

6. Pliability

Pliability is the property, that enables one Fibre to be easily wrapped around another in the spinning operation. The lack of this property will make the Fibre brittle.

7. Durability.

Durability means that the textile Fibres must be capable of withstanding ordinary kinds of wear to which it is reasonably subjected. It will decide the usage time of the product.

8. Luster

Another quality, that enhances the value of textile Fibre, is luster. Fibre possesses this quality such as silk, mercerized artificial silk, etc., and is capable of producing beautiful effects. The luster however is not an essential property but is an ornamental property.

9. Porosity

Porosity meant that the Fibre should be capable of easily absorbing liquids and solutions. This is essential for dyeing, bleaching, and other finishing processes. Fibres that cannot be dyed or bleached would have a limited application in the manufacture of textiles.

10. Uniformity

It means the evenness in length and diameter of the Fibre enhances the spinning quality very much and produces an even thread.

11. Moisture Relations

The moisture relation will affect the following

Comfort wearing

Percentage of shrinkage

Drying and wetting percentage

Development of elasticity

12. Density

The density of the Fibre depends upon the weight of the molecule of which it is made and how closely they are packed together. It is necessary in the development of cloth construction.

13. Availability

To possess commercial value Fibre must be available in large quantities and its supply more or less constant and cheap. The minimum availability will affect the production.

CLASSIFICATION OF TEXTILE FIBRE

Textile Fibres are divided into two classes based on their length.

➤Fibre

➤Filament

The word Fibre is usually used when speaking of cotton, coir, wool, and filament for rayon, silk nylon, etc. Filaments are natural and manufactured Fibres of continuous length. Staple Fibres are those, that are, cut into short lengths for spinning with wool cotton, or other textile Fibres.

CLASSIFICATION OF TEXTILE FIBRES

Textile Fibres are broadly classified into two groups based on their source of origin.

➤ NATURAL FIBRE

➤ MAN MADE FIBRE (ARTIFICIAL FIBRE)

This group can be further subdivided into subgroups.

NATURAL FIBRE

Natural Fibres are Fibres provided by nature in the fibrous form.

The natural Fibres are divided into three main groups.

Vegetable Fibre

Animal Fibre

Mineral Fibre

Vegetable Fibre

It contains in addition to cellulose, the usual constituents of vegetable cells. They are hemicelluloses and lignin, oils and wax, natural coloring matters, moisture and mineral matters. The vegetable Fibres are obtained from the seeds, bast (Bass), leaf, and fruits of the plants.

E.g.: cotton, linen (flax), Jute, Sisal, Manila hemp, and coir.

Animal Fibre

These are getting from animals. They are nitrogenous substances (meant to combine with Nitrogen or to supply nitrogen) and contain oxygen, Hydrogen, and carbon. They are also known as protein Fibres.

E.g.: Wool and silk.

Wool occurs as animal hair (Appendage) and silk is produced as a continuous filament by larvae of silkworms. (Secretion)

Mineral Fibre

These are natural substances (not vegetable or animal) obtained from mines.

E.g.: Asbestos, Glass.

ARTIFICIAL (MAN-MADE) FIBRE

Using suitable chemicals and auxiliaries makes artificial Fibres.

Man-made Fibres are divided into two main groups.

1. Semi-synthetic Fibre or Re-generated Fibre

2. Synthetic Fibre

. Semi-synthetic Fibre or Re-generated Fibre

They are made from vegetable sources and animal sources. The cellulose in the vegetable source or the proteins in the animal source is converted into a viscous solution and the solution is passed through a spinneret and then evaporated to form a long continuous filament by using suitable chemicals.

E.g.: Viscous Rayon Acetate Rayon Casein filament - Animal Protein

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2. Synthetic fibre

Synthetic Fibres are prepared from simple organic compounds. I.e., The raw material is not naturally occurring fibrous materials. The organic compounds are usually derived from the byproducts of petroleum.

E.g.: Terylene, Nylon

DYES AND DYEING 

 The term dyeing means coloring of various materials especially textile fibres in such a manner that the color cannot be removed by stripping or by washing. Moreover, the color must be distributed right to the whole material and not color simply on the surface like a painted article. The dyeing property of a material depends on the material to be dyed. Fixation of a dyestuff on a material by chemical processing is called dyeing.

CLASSIFICATION OF DYES

Based on the methods of application the dyes are classified as follows.

Acid dyes

Basic dyes

Direct dyes

Mordant dyes

After chrome dyes

Developed dyes

Coupled dyes

Sulphur dyes

Naphthol dyes

Vat dyes

Oxidized dyes

Dispersed dyes

Reactive dyes

Dyestuff For Coir

While in use the coir products are subjected to exposure in the light and rubbing. They should have the properties such as colorfastness towards the light, rubbing, and washing and the cost of the dyes and dyeing should be less. Most of these requirements can be met with acid, basic, and direct dyes. All the basic dyes are suitable for coir Fibre and yarn. Many of the acid and direct dyes are processing sufficient affinity towards coir.

BASIC DYES

Basic dyes are organic dyes based on certain types containing amino groups. This dyestuff has having direct affinity towards silk, wool, nylon, jute and coir. This dyestuff will produce brilliant shades and have great tentorial power (a small quantity of dyestuff produces a large number of colors and dyes more quantity of material) but these dyestuffs are poor in light fastness. Some of the basic dyes, which are commonly used for dyeing of coir in the coir industry, are

➤ Auramine OA (Yellow)

➤ Rhodamine B 500 (Pink) 5e

➤ Chrysoidine YN (Reddish Brown)

➤ Bismark Brown RLN (Brown)

➤ Magenta 2B (Rose)

Pink

►Malachite Green XLS (Green)

➤ Methyl Violet (Violet)

➤ Methylene Blue (Blue)

➤ Coir Blue AR (Dark Blue)

➤ Basic Black (Ash Black)

METHOD OF APPLICATION OF BASIC DYES ON COIR

The required quantity of dyestuff is pasted with an equal quantity of acetic acid (the strength of acetic acid will be 99.99% which is called glacial acetic acid) and brought into solution by adding hot water with proper stirring of the solution. The dye bath is set with the required quantity of water maintaining the material, solution ratio 1:12 to 1:15 for yarm and 1:20 to 1:24 for Fibre, and add required quantity of dye bath assistant (2% acetic acid on the weight of material) and stir