Faculty of Engineering Department of Textile Engineering

The mentioned students have completed their project work "Comparative study of colorimetric and authenticity properties of different dyes on cotton and viscose fabrics" under my supervision. Deep knowledge and great interests of our supervisor in textile dyeing and finishing influenced us to convey the project work. We would like to extend thanks to our full coursemates in Daffodil International University who participated in the discussion while completing the coursework.

Cotton and 100% viscose knit fabric dyed with Reactive, Direct, Vat Dyes for 2% hue is reflectance % and carve ware contested and L.a.b.c values and K/S (color strength) also measured by using spectral meter color fastness to wash and rub test was performed to compare staining perform. Figure-4.1.2 Comparison of color matrix K/S value in bar chart 31 Figure-4.1.3 Comparison of color matrix value in bar chart L,a,b,c, 32 Figure-4.1.1.1 Reflectance% for tub dye on cotton and viscose fabric 33 Figure-4.1.1.2 Compare color matrix K/S value in bar chart 34 Figure-4.1.1.3 Compare color matrix L,a,b,c, value in bar chart 35 Figure- 4.2.1 Bar chart color change fastness for washing cotton and viscose sample. 28 Table -4.1.1 Comparison of cotton metric value of cotton and viscose with direct dye 30 Table -4.1.2 Comparison of cotton metric value of cotton and viscose with direct dye 31 Table -4.1.1.1 Comparison of cotton metric value of cotton and viscose with vat dye 33 Table-4.1.1.2 Comparison of cotton metric value for cotton and viscose with vat dye 34 Table-4.2.1 Comparison of color fastness to wash with reactive dye 36 Table-4.2.2.1 Comparison of color fastness to wash with direct dye 37 Table -4.2.3.1 Comparison of color fastness to wash with tub dye 38 Table-4.3.1 Comparison of rub fastness to wash with reactive dye 39 Table-4.3.2.1 Comparison of rub fastness to wash with direct dye 40 Table-4.3.3.1 Comparison of rub wash fastness with vessel color 41.

Cotton is a soft, fluffy staple fiber that develops in a boll or protective sheath around the seeds of the cotton plants of the genus Gossypium in the mallow family Malvaceae. The viscose process dissolves pulp with aqueous sodium hydroxide in the presence of carbon disulfide. It is also used in industrial yarns, upholstery and carpets, and in cellophane molding.

Cotton, Viscose, fabric Comparison was done on the basis of color strength (K/S) Colorimetric value (L*,a*,b*,c*) and color fastness properties.

The Current World Cotton Situation

During the last years the global economic growth has been more than 3% and has created a good environment for the textile industry. Until the Asian economic crisis develops in the second half of 1997, the global economy will grow by 1% or 4% in 1998. As a result of the crisis, the International Monetary Fund lowered its 1998 economic growth forecast to 3%.

This reduction in global income is expected to be quite strong in economic growth as it passes through Japan. Cotton grading is used to determine the quality of cotton fibers in grades, length and micrometers [3]. Previously these qualities were graded only by an experienced classroom hand and eye.

However, other characteristics of cotton fibers are also being developed, namely measuring ripeness and measuring techniques such as short fiber content.

Table bellow shows the production and cost of leading cotton producing countries in millions of tons in 2002

Physical properties of Cotton

Fiber Length
Length Uniformity
Fiber Strength
Micronaire value
Color
Trash

A constant mass of cotton fibers (2.34 g) is compressed into a space in the known volume, and the wind permeability measurement of this compacted sample is taken. The work at the University of Tennessee uses the spectrometer's CI-based average color measurement and a color uniformity measurement, through image analysis, using image analysis to improve accuracy and provide additional measurements for color grading. The waste material is evaluated to scan cotton sample pages with a video camera and calculate the percentage of surface area covered by waste particles.

Reactive dye

History of Reactive dye
Mechanism of reactive dye
Direct dye
Mechanism of Direct dye
Vat Dye

It is anionic dye, also called direct essential dye, it is one of the most versatile classes of dyes applicable to cellulose, wool, nylon fabric. Electrolyte addition (such as sodium chloride, sodium sulfate) helps neutralize the spread and fatigue of direct anemia by neutralizing the negative surface charges of cellulosic fibers. The most common depleting agent is sodium hydrosulfite (Na2S2O4), which converts Dike into a soluble form of its "lemon" form.

Chemical reactions such as oxidation, reduction and pH control are often required; Even for the reduction of the dissociation process, the exact amount of sodium and sodium hydroxide measurement is the necessity for measuring the amount.

A Short Background to Regenerated Cellulose and Viscose Rayon

Indigo is an example of this dice class: it changes from yellow, diabetes, green, and then from blue to sky. By the way, these five processes are currently called; Cellulose nitrate (no longer produced), viscose rayon, modal and liquid. This problem is not a problem for modal and cellulosic fibers, as wet energy has been improved.

Due to the production process of reproduction of cellulose fibers, they can look similar and it can be challenging to distinguish between fiber recognition assays. To complicate matters further, they can resemble other man-made fiber types, such as acrylic. A person working in the laboratories of the Royal Botanic Gardens discovered the vascular process of reducing cellulose in 1829 by three British chemists, Charles Cross, Clayton Beadle and Edward Beven.

The creation of viscose rayon fibers instead comes after a fellow Kew worker, Charles Topham's invention of a centrifugal spinning method for extruding filaments, Topham's supervisor, realized the potential of Topham's spinning method for the viscose process to patent it in 1898 get for textile fibers. The process proved inconsistent and unreliable. Commercial success for viscose rayon only came after Samuel Courtauld and co. Ltd – later Courtaulds Ltd – bought the rights to the viscose process in 1904 and embarked on a large-scale production process.53 In 1905 they opened a factory in Coventry and began producing viscose rayon.

Manufacturing of viscose rayon

Properties of Viscose Rayon

Material

Fabric Speciation

Recipe

Reactive dye
Direct Dye
Vat Dye

Method

Dyeing Method and Curve

Reactive dye
Direct Dye
Vat Dye

Collection of pre-treated 100% cotton fabric. Vat temperature at 80 degrees for 5 minutes. Paint temperature at 100 degrees for 15 minutes.

Test Method

Spectral Analysis
Color fastness to wash test
CF to Rubbing test

Since the K/S value is higher in viscose compared to cotton, the shade will be darker in viscose for the same dye. From the values for L,a,b,c it can be said that the shade will be lighter, more green and less blue and almost equal in color purity in cotton fabric than in viscose. Since the K/S value is higher in viscose compared to cotton, the shade will be lighter in viscose for the same dye.

From the values of L,a,b,c, we can say that the shade will be lighter, more obvious and less blue and almost similar in color purity for cotton fabric than for viscose. According to the values of L,a,b,c, we can say that the shade will be similar, greener and readable and almost equally bright with a similarly bluer color for cotton fabric than for viscose. Figure-4.2.1 Bar chart of color change fastness when washing cotton and viscose sample with reactive dye.

Figure 4.2.2.1 Bar chart Color change fastness when washing cotton and viscose sample with Direct dye. Better and comparable results were found for both cotton and viscose fabrics with direct dyeing, but in both cases little strong dyeing was found for cotton. For direct dyes, the reflectance values were found to be 14.37%. for cotton and 11.57% for viscose at 580 nm and 580 nm for barrel dye, respectively. The reflectance values were found to be 33.17%. for cotton and 34.80% for viscose at 600 nm and 600 nm, respectively. . ii) Since the K/S value is higher in viscose compared to cotton, the shade will be darker in viscose for the same dye percentage. For direct dyes Because the K/S value is higher in viscose compared to cotton, the shade will be lighter in viscose for the same dye.

For vat dyes As K/S value is higher in viscose compared to cotton, the shade will be darker in viscose for the same dye %. . iii) L, a, b, c, for reactive dyes From the values of L,a,b, c it can be said that the shade will be lighter, greener and less blue and almost similar in purity of color in cotton fabric than in viscose . For direct dyes From the values of L,a,b,c it can be said that the shade will be lighter, more readable and less blue and almost similar in purity of color in cotton fabric than in viscose. For direct dyes Better and similar results were found for both cotton and viscose fabrics with direct dyes, but litile high stains were found for cotton in both cases.

Poor wet rub resistance was found for direct dyed cotton fabric (2-3), and then for direct dyed viscose fabric (4). Cotton should.