Colorant Database for Cationized Cotton.

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ABSTRACT

MANDAL, SONALI. Colorant Database for Cationized Cotton. (Under the direction of Dr. Peter J. Hauser.)

The use of cationized cotton is currently one of the sustainable methods of

dyeing cotton with anionic dyes like fiber-reactive and direct dyes. It enables the dyeing

of cotton without the use of salt and with higher dye exhaustion. During the dyeing

phase of wet processing, the effluent load is reduced considerably with good fastness

properties. However, even with all these benefits the use of cationized cotton lacks

acceptance in the industry. The most commonly used cationization agent is

3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC). Several studies reported

appearance of change in hue in samples dyed with cationized cotton. This problem

potentially restricts the use of current primary databases in predicting dye recipes

when using cationized cotton. Hence it is necessary to develop new primaries for

cationized cotton.

In this study, a colorant database was developed for 23 reactive dyes of various

classes and manufacturing companies. These dyes were selected on the basis of their

current use in industry as primary colorants for developing shades. Two treatment

levels of CHPTAC were applied on cotton and samples were dyed at various % shades. It

was observed that cationized cotton primaries gave better match to the standard than

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Colorant Database for Cationized Cotton

by Sonali Mandal

A thesis submitted to the Graduate Faculty of North Carolina State University

in partial fulfillment of the requirement for the degree of

Master of Science

Textile Chemistry

Raleigh, North Carolina

2013

APPROVED BY:

Dr. David Hinks Dr. George Hodge

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DEDICATION

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BIOGRAPHY

Sonali Mandal, daughter of Uttam Kumar Mandal and Sulekha Mandal, was born on

September 28, 1989 in Mumbai, India. She has a younger brother Abhishek Mandal. She

graduated from Fr. Agnels Multipurpose School & Junior College in 2007. She obtained

her Bachelor of Technology degree in Fiber and Textile Processing Technology from the

Institute of Chemical Technology (previously known as University Department of

Chemical Technology), Mumbai in 2011. She will receive her Master of Science degree

in Textile Chemistry in 2013 and will remain at North Carolina State University to

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ACKNOWLEDGMENTS

I want to thank Dr. Peter J. Hauser for his patience, time and guidance during the

research and writing this thesis. Also, I want to thank Dr. David Hinks and Dr. George

Hodge for their general advice and guidance. A special thanks to Mr. Jeffery Krauss, the

dyeing and finishing pilot lab manager for always being available and for helping me

perform the experiments in the lab. This research would not have been possible

without the financial support of Cotton Incorporated. I want to thank all the staff at

Cotton Incorporated, especially Mary Ankeny. I want to also thank my family especially

my parents for encouraging me to pursue my graduate studies in the USA and providing

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TABLE OF CONTENTS

LIST OF TABLES ... vii

LIST OF FIGURES ... x

1. Introduction ... 1

2. Literature Review ... 3

2.1 Cotton Fibers ... 3

2.2 Coloration of Cotton ... 4

2.2.1 Vat Dyes ... 4

2.2.2 Sulfur Dyes ... 5

2.2.3 Pigments ... 5

2.2.4 Natural Dyes ... 6

2.2.6 Direct Dyes ... 6

2.2.7 Reactive Dyes ... 7

2.3 Chemistry of Reactive Dyes ... 7

2.4 Environment issues related to Reactive dyes ... 13

2.5 Cationization of Cotton with CHPTAC ... 15

2.6 Colorant primaries and color matching ... 20

2.7 Need for new primaries ... 27

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3.1 Materials ... 28

3.2 Equipment ... 31

3.3 Pretreatment Procedure ... 31

3.4 Cationization Procedure ... 32

3.5 Dyeing Procedures ... 32

3.6 Evaluation Procedures ... 41

3.7 Colorant Database Evaluation ... 42

4. Results and Discussion ... 43

4.1 Dyed Cationized cotton samples ... 43

4.2 Comparison of K/S values ... 44

4.3 Comparison of L*, a* and b* values ... 68

4.4 Repeatability in dyeing cationized cotton ... 80

4.5 Comparison of dye bath exhaustion ... 83

4.6 Comparison of fastness test ratings ... 85

4.7 Color matching using conventional and cationized primaries ... 94

5. Conclusions ... 106

6. Recommendations for Future Work ... 108

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LIST OF TABLES

Table 1: List of Chemical and Auxiliaries ... 29

Table 2: List of Dyes ... 30

Table 3: Concentration of Glauber’s salt and Soda Ash used in Dyeing Samples ... 33

Table 4: Conventional Dyeing Procedure for Novacron Dyes. ... 35

Table 5: Conventional Dyeing Procedure for Remazol Dyes. ... 36

Table 6: Conventional Dyeing Procedure for Drimaren K Dyes. ... 37

Table 7: Conventional Dyeing Procedure for Drimaren CL Dyes. ... 38

Table 8: Conventional Dyeing Procedure for Drimaren X Dyes. ... 39

Table 9: Dyeing Procedure for Cationized Cotton samples. ... 40

Table 10: K/Ssum values for Reactive Yellow 143 ... 45

Table 13: K/Ssum values for Reactive Red 238 ... 48

Table 15: K/Ssum values for Reactive Blue 235 ... 50

Table 17: K/Ssum values for Novacron Super Black R ... 52

Table 18: K/Ssum values for Novacron Super Black G ... 53

Table 19: K/Ssum values for Remazol Golden Yellow RGB ... 54

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Table 28: K/Ssum values for Reactive Black 5 ... 63

Table 29: K/Ssum values for Reactive Orange 70 ... 64

Table 33: L*, a*, b* values of CD, C25 and C50 samples ... 69

Table 34: Repeatability in Dyeing Cationized Cotton on 50 g/L CHPTAC fabric ... 81

Table 35: Wash Fastness Test Results ... 85

Table 36: Crock Fastness Test Results ... 89

Table 37: Recipes for dyeing the standards (targets)... 95

Table 38: Auxiliaries for Dyeing the Standards ... 96

Table 39: Dyeing Procedure for the Standards. ... 96

Table 40: Recipes for Dyeing Green Thumb Shades ... 98

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Table 42: Recipes for Dyeing Solar Wind Shades ... 100

Table 43: Recipes of Dyeing Heavy-Hearted Shades ... 101

Table 44: Recipes for Dyeing Green Thumb Shades with Remazol Dyes ... 103

Table 45: Recipes for Dyeing Stained Wood Shades with Remazol Dyes ... 104

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LIST OF FIGURES

Figure 1: Chemical Structure of Cotton ... 3

Figure 2: Reactive Dye features ... 8

Figure 3: Fiber-reactive groups in commercial reactive dyes. [7] ... 10

Figure 4: Reactions of DCT reactive dyes ... 12

Figure 5: Reactions of VS reactive dyes ... 13

Figure 6: Dyeing of Cationized Cotton ... 16

Figure 7: Synthesis of CHPTAC ... 17

Figure 8: Reactions of CHPTAC ... 18

Figure 9: CIELAB Color Space ... 22

Figure 10: Plot of K/S vs dye concentration for a sample [35] ... 26

Figure 11: Plot of K/Ssum vs. % Shade for Reactive Yellow 143 ... 45

Figure 14: Plot of K/Ssum vs. % Shade for Reactive Red 238 ... 48

Figure 16: Plot of K/Ssum vs. % Shade for Reactive Blue 235 ... 50

Figure 18: Plot of K/Ssum vs. % Shade for Novacron Super Black R ... 52

Figure 19: Plot of K/Ssum vs. % Shade for Novacron Super Black G ... 53

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Figure 21: Plot of K/Ssum vs. % Shade for Remazol Red RGB ... 55

Figure 29: Plot of K/Ssum vs. % Shade for Reactive Black 5 ... 63

Figure 30: Plot of K/Ssum vs. % Shade for Reactive Orange 70 ... 64

Figure 34: Dye exhaustion for Reactive Yellow 176 ... 83

Figure 35: Dye Exhaustion for Reactive Red 197 ... 84

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1. Introduction

Clothing is regarded as one of the basic necessities for human beings and the

textile industry holds a significant share in global trade in manufactured goods. A

research by the Secretariat of the Seoul International Color Expo reveals that 84.7%

respondents think color as an important factor while choosing products [1]. The

coloration of textile goods thus acts as an important process in the textile industry.

Cotton is the most important natural fiber in the world due to its incomparable

properties. The textile dyeing and finishing sector is known to consume large

amounts of water and chemicals. Many efforts are being made to develop

ecofriendly dyeing processes with lesser consumption of dyes and auxiliaries. The

process of treating the effluent from the textile industry is an important step so as

the make the effluent safe for discharging into water streams. However, these

treatments are expensive and are not always viable since a typical textile effluent

contains various types of dyes, metals, surfactants and other auxiliaries. Also,

treating the effluent does not reduce the usage of the dyes and chemicals.

Cotton is mainly dyed with reactive dyes which require large amounts of salt to

increase the dye affinity. However, the salt does not get exhausted and remains in

the bath along with unexhausted and hydrolyzed dye. Also, in order to get rid of the

hydrolyzed dye from the fiber, post dyeing scouring and multiple rinsing stages are

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solution to these problems is the use of cationized cotton. Cotton is treated with a

cationic agent to attract the anionic dye molecules. The use of cationized cotton

eliminates the need of salt, scouring and multiple rinsing processes. Also, with an

appropriate level of treatment lesser amount of dye is needed to obtain shades

comparable to conventionally dyed cotton samples.

In this present work, cotton fabric was cationized using

3-chloro-2-hydroxyproplytrimethylammonium chloride and was then dyed with fiber reactive

dyes. The dye exhaustion and the final shade obtained on cationized cotton are

different compared to conventional cotton dyeing which the existing primaries

cannot be used for color matching on cationized cotton [2, 3]. Specifically, the work

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2. Literature Review

2.1 Cotton Fibers

Cotton is the most abundant fiber available in nature consisting of 88-96%

cellulose [4]. Cotton possesses unique properties such as softness, comfort and

breathability which make it the most popular among natural fibers [5]. The factors

that affect the properties of cotton are color, impurities, molecular weight, fiber

length, uniformity of length etc. The leading producers of cotton in the world are

China, USA, India, Pakistan and Brazil [6].

Figure 1: Chemical Structure of Cotton

Cellulose, a polymer of glucose formed by condensation polymerization of

β-D-glucopyranose joined by 1, 4-glucosidic bonds, is the basic building block for cotton

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reactive and participates in the cellulosic reactions. Currently, cotton constitutes

about 50% of the annual textile fiber production [8].

2.2 Coloration of Cotton

2.2.1 Vat Dyes

Vat dyes are one of the oldest types of dyes used for dyeing of cotton. Indigo is

the most popular vat dye used for dyeing blue denim [9]. Vat dyes are water

insoluble and hence needs to be reduced chemically to their leuco water-soluble

forms for application on cotton. The process of reduction of vat dyes is known as

vatting in which the dye reacts with a reducing agent and a base. The most

commonly used reducing agent is sodium hydrosulphite which is stable in the

presence of an alkali. After the leuco form of the vat dye has been applied on the

fiber it needs to reoxidized to its original form using atmospheric oxygen or mild

oxidizing agents like sodium per borate or hydrogen peroxide. This class of dye

possesses excellent fastness properties however they are costly and have less range

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2.2.2 Sulfur Dyes

Sulfur dyes are similar to vat dyes which are used for dyeing cotton [6]. They

contain sulfur linkages in their structure however the exact molecular chemistry is

still unknown [7, 11]. Currently, one of the most important sulfur dyes is C.I.

Sulphur Black 1[9]. Similar to vat dyes, sulfur dyes are also water insoluble and

need to be converted into their leuco forms in presence of a reducing agent and an

alkali. The combination of sodium sulphide as reducing agent along with sodium

hydroxide is traditionally used for solubilizing these dyes [7]. After the dye is

applied on the cotton substrate it needs to be reoxidized either by atmospheric

oxygen or with mild oxidizing agents like hydrogen peroxide [12]. Sodium sulphide

remains in the effluent which can undergo acidification to produce hydrogen

sulphide, a harmful chemical [7]. Hence this effluent needs to be treated before

releasing into water streams.

2.2.3 Pigments

Pigments possess color rending properties and are insoluble in the medium of

application. Since they cannot penetrate inside the fiber, they need to be fixed on the

surface of the fiber by using a polymeric adhesive binding agent [12]. The fastness of

the substrates colored with pigments depends on the mechanical properties of the

binder [13]. The application of pigment on cotton is laborious and also stains the

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system influences the properties of the cotton substrate by imparting stiffness and

possesses moderate to poor fastness ratings [13].

2.2.4 Natural Dyes

Natural dyes are those colorants that have natural source of origin like plants,

invertebrates, minerals etc. [14]. Indigo is possibly the oldest and the most

important among all the naturally occurring dyes [15]. The process of extraction of

the natural dyes from their raw materials is a tedious work. Natural dyes are

expensive due to low color yields and limited source of raw materials. Most natural

dyes do not have affinity for cotton and hence are bonded using a mordant which

acts are a chemical bridge between the dye and fiber thus improving their fastness

properties [14]. They possess poor light fastness on cotton due to its hygroscopic

nature [16]. The dye undergoes photochemical oxidation in presence of moisture

leading to poor light fastness [17]. Hence, the fastness of the dye depends on the

binding strength of the mordant.

2.2.6 Direct Dyes

Direct or substantive dyes have very high affinity for cellulosic fibers due to their

narrow and flat molecular structure [12]. The straight structure of these dyes often

contains one or more azo groups that are held to cellulose by secondary bonds like

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exhaustion rates can be achieved by adding salt or increasing the dyeing

temperature [11]. However, they do not possess good wash and light fastness

properties. The wash fastness can be improved by treating with a dye fixing agent

that increases the molecular weight of the dye already absorbed in the fiber.

2.2.7 Reactive Dyes

Reactive dyes are the class of dyes which are capable of forming strong and

stable covalent bonds with cellulose [12]. Reactive dyes are widely chosen for

dyeing cotton because of their wide range of brilliant shades, multiple methods of

application and good fastness properties. However, some reactive dyes have poor

light and chlorine fastness. The method of dyeing regular cotton with reactive dyes

follows three steps: exhaustion, fixation and washing-off. Glauber’s salt, sodium

sulfate, is used for the exhaustion of reactive dyes and the washing-off step

consumes large quantities of water. Due to these reasons the application of reactive

dyes exhibits significant environmentally impact.

2.3 Chemistry of Reactive Dyes

Rattee and Stephen in ICI England first developed the fiber reactive dyes in 1955

and the dyes were commercialized in 1956 [7]. The reactive dyes have structure

similar to acid or direct dyes and additionally have a reactive group which reacts

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Figure 2: Reactive Dye features

(C = Chromophore, S = Solubilizing group, B = Bridging group, R = Reactive group,

L = Leaving group) [18]

A typical reactive dye will contain a chromophore, solubilizing groups, a bridging

group, a reactive group and leaving groups as shown in Figure 2. Each of these

features influences the dyeing and the fastness properties of the dye. The

chromophore is the color imparting group of the dye. The solubilizing groups make

the dye molecule water soluble. The bridging group connects the chromophore to

the reactive group of the dye. The reactive group contains leaving groups which are

replaced during the dyeing process. The most common reactive groups can be

classified into halogenic cyclic azine derivatives and sulfatoethylsufone type

C

S

B

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reactive dyes. The different types of reactive dyes commercially available are shown

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Dichlorotriazine (DCT) Monochlorotriazine (MCT)

Monofluorotriazine (MFT) Trichloropryimidine (TCP)

Difluorochloropyrimidine (DFCP) Dichloroquinoxaline (DCQ)

Nicotinyltriazine (NT) Vinylsulphone (VS)

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The dye fixation occurs in presence of alkali in which the reactive group of the

dye reacts with hydroxyl groups of the cellulose. However, the dye may undergo

hydrolysis with hydroxide in water. This hydrolyzed dye is incapable of forming

bonds with the cellulose and reduces the wet fastness properties if these hydrolyzed

dyes are not removed fully during the washing. Multiple soaping and rinsing steps

are required after the dyeing process in order to remove these hydrolyzed dyes. The

reactions of dichlorotriazine and vinylsulphone types of reactive dyes are shown in

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Figure 4: Reactions of DCT reactive dyes

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Figure 5: Reactions of VS reactive dyes

2.4 Environment issues related to Reactive dyes

The process of dyeing cotton with most reactive dyes requires large amounts of

salt (electrolyte) for exhaustion as well as alkali for fixation. In order to remove the

hydrolyzed dye formed during the fixation, scouring and multiple rinsing steps are

required. Hence, the large volume of effluent produced typically contains high

concentrations of salt and alkali which pollute the environment if not treated.

The hydroxyl groups present in the cotton ionize in contact with water thus

producing negative charges [19]. Reactive dyes are anionic in nature and thus get

repelled by the negative charges on the cotton fiber. Thus salt is added in the bath in -OH

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order to reduce these negative charges and increasing the affinity of the dye for the

fiber. For high exhaustion of the dye, large quantities of salt are required (40-100

g/L) [20]. However, these salts remain unexhausted and are added to the effluent.

The process of removal of salt from the effluent adds to the cost of production.

Even after using high concentrations of salt, complete exhaustion of the dyestuff

cannot be achieved, only 60-65% gets utilized in normal dyeing systems [21]. These

unexhausted dyes remain in the bath along with the hydrolyzed dye. Processes like

chemical oxidation destroy the chromophore of the dye but may ultimately produce

even more toxic compounds than the original dye [22]. A process that can consume

less amount of dye and has high dye exhaustion can be a solution to this problem.

In order to achieve good fastness properties, it is important to remove the

hydrolyzed dye from the dyed cotton substrate. Studies show that, rinsing steps

consume approximately 80% of water, 90% of energy and 70% of time required in

the complete dyeing process [23]. Water is consumed for rinsing after the dyeing

cycle, scouring process and final rinsing step to remove the hydrolyzed dye. Also,

these stages make the entire dyeing process time consuming, thereby reducing the

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Irrespective of these drawbacks, reactive dyes are preferred over other dyes for

dyeing cotton due to overall fastness and wide range of hues. Many technologies

have been suggested to overcome the environmental problems associated with

reactive dyes. However, many of these lack practicality.

2.5 Cationization of Cotton with CHPTAC

The use of cationized cotton is a sustainable method of dyeing cotton. It is

possible to achieve 100% dye exhaustion with less dye, energy and time than

conventional dyeing application methods through the use of cationized cotton [24].

It is possible to dye cotton with the use of salt and obtain high dye exhaustion and

comparable or better color fastness [19]. Cationized cotton can be obtained by

reacting cotton with a cationizing agent. This treatment imparts positive charges on

the cotton fiber which eliminate the anionic dye repulsive forces as illustrated in

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Figure 6: Dyeing of Cationized Cotton

3-chloro-2-hydroxyproplytrimethylammonium chloride (CHPTAC) is a

cationizing agent that can be used to produce cationized cotton.

CHPTAC is formed by the reaction of epichlorohydrin and trimethylamine

hydrochloride as shown in Figure 7.

Cotton Fiber

Cationizing Agent

Dye-SO3

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Figure 7: Synthesis of CHPTAC

CHPTAC in alkaline conditions forms EPTAC which further reacts with cellulose

to form ether linkages as shown in Figure 8. However, EPTAC can also undergo

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CHPTAC EPTAC

EPTAC Cationized Cotton

EPTAC Diol

Figure 8: Reactions of CHPTAC

CHPTAC can be applied to cotton by various methods like cold pad-batch, pad

steam, pad bake and exhaust; however, the cold pad-batch is the most efficient

method for the cationization treatment [3, 18]. The fixation efficiency is observed to

decrease with increasing liquor ratio and temperature because EPTAC hydrolysis

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temperature. A higher fixation of the cationizing agent on cotton can be obtained by

using additives like sodium lauryl sulfate, triethanol amine, ethylene diamine

tetraacetic acid etc in the exhaust method as they tend to complex with CHPTAC

thus reducing the hydrolysis reaction [25].

It has been also observed that the fixation of the cationizing reagent on

mercerized cotton is nearly double that of unmercerized cotton [3]. By use of

cationized cotton it is possible to obtain higher color yields with direct, acid and

reactive dyes [26]. The dye molecular structure has an important role when applied

on cationized cotton as it is seen that the color yield differs for different dye

chemistry [27]. The use of cationized cotton is not limited to cotton dyeing.

Cationized cotton can also be printed using acid, direct and reactive dyes. The

printed cationized cotton samples have higher color yield, similar or better fastness

properties and shorter processing cycles compared to untreated cotton [28-32].

Since direct, acid and reactive fiber dyes have high affinity for cationized cotton it

can be used for removal of the dyes from the textile effluents just by cationizing

waste cotton fibers. It is almost possible to remove the dyes completely from the

effluent and meet the EPA standard with lower cost compared to other waste water

treatment techniques [33].

One of the drawbacks of cationic cotton treatment with CHPTAC is the reduction

of whiteness index of the treated fabric compared to the untreated bleached fabric

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irritant with is a product of the reaction of CHPTAC with sodium hydroxide [7].

Hence, it is recommended to mix the two chemicals directly in the pad trough just

before the padding process in order to minimize the risk of occupational exposure.

2.6 Colorant primaries and color matching

The relationship between supplier and customer is very important in the current

textile market. However, many times there are differences in the judgment of color

matching if it is solely based on a human observer [34]. Hence, it is important to

measure color differences on color measuring instruments. A spectrophotometer

measures the reflectance of a sample across the visible spectrum. Reflectance is the

ratio of reflected light and incident light. A spectral analyzer measures the reflected

light and splits into its spectral components [35]. In dyeing textile goods, dyes are

mixed in different proportions to obtain a color and this is called subtractive mixing.

In subtractive mixing, red, yellow and blue are the primaries when used in different

proportions to obtain a color. The tristimulus values (X, Y, and Z) are the three

primaries required to produce a color [36]. The chromaticity coordinates (x, y, and

z) are given by:

Equation 2.1

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Equation 2.3

Since x + y + z=1, it possible to plot these chromaticity coordinates on a two

dimensional plot with x and y as axes called the chromaticity diagram which consists

of [35]. It is possible to calculate the value of X and Z from x, y, and Y.

If a sample is viewed under a specific light source, the amount of light reflected at

each wavelength can be given by Eλ * Rλ, where Eλ is the amount of light emitted and

Rλ is the amount of light reflected at each wavelength. The reflected light can be

matched using the mixture of the three primaries X, Y and Z using the formula [35]:

Eλ Rλ [λ] ≡ Eλ Rλ xˉ [X] + Eλ λ Rλ yˉ [Y] + Eλ λ Rλ zˉ [Z] λ Equation 2.4

The total amount of energy reflected is the sum of Eλ * Rλ over the visible spectrum

of λ 380 to 760 nm. Similarly, the light reflected from a sample can be given by

Σ Eλ Rλ xˉ + Σ Eλ λ Rλ yˉ + Σ Eλ λ Rλ zˉ λ Equation 2.5

From equations 2.4 and 2.5

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Since, Eλ, R, xˉ ,yλ ˉ , zλ ˉ are known, it is possible to calculate the tristimulus values for λ

a particular sample.

The CIELAB color space is a three dimensional system is based on three color values

[35]:

Figure 9: CIELAB Color Space

L*: lightness or black to white contribution

a*: red to green contribution

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The color difference is calculated from the ΔE*ab numeric value which is calculated

by the equation:

ΔE*ab = √ Equation 2.6

Where,

ΔL*, Δa* and Δb* are the difference in the L*, a* and b* values between the sample

and the reference color.

Color difference can also be expressed in terms of lightness difference ΔL*, chroma

difference ΔC* and hue difference ΔH*.

The CMC color difference formula is given as

ΔE CMC =

√

Equation 2.7

l and c are tolerance parameters for weighting of the lightness and hue differences

and for textile coloration, normally l = 2 and c = 1.

SL =

for L*S ≥ 16 else SL = 0.511

SC =

+ 0.638

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f =

√

and

T = 0.38 + |0.4 Cos (35°+ hab,S)|

In the hue angle domain 164°≤ hab,S ≤ 345°, the equation

T = 0.56 + |0.2 Cos (168° + hab,S)| is valid.

The subscript S refers to the sample color.

The ΔE CMC value helps to decide how close the sample matches the reference

standard. The recipe prediction and color matching process has the following

stages: calibration of colorants, measurement of the standard, recipe computation

and recipe correction.

From the Kubelka-Munk theory the function K/S is given by the equation:

K/S =(c1K1+ c2K2+ c3K3+…..+Ks)/Ss Equation 2.8

Where,

c: concentrations of colorants

K: absorption coefficients

S: scattering coefficients

Subscript s identifies substrate and subscripts 1, 2, 3…. identify the individual

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Kubelka-Munk theory assumes that the colorant on a substrate reflects and

scatters light and the light loss through the edges is neglected [35, 36]. It also

assumes uniform distribution of dyes and pigments throughout the sample and

absence of interaction between them. Hence, the K/S function leads to non-linearity

at high dye concentration with low reflectance values.

To calibrate the colorants, the textile substrate is dyed at different

concentrations of each individual dye and read in the spectrophotometer to obtain a

reflectance at each interval of the wavelength as a function of dye concentration.

The relationship between K/S and reflectance is given by:

f (R) or K/S = (1-R∞)2/2 R∞, Equation 2.9

Where,

R∞: reflectance of light of a given wavelength by a sample of infinite thickness.

Although the relationship between reflectance and dye concentration is

nonlinear, the relationship between K/S and dye concentration is near linear for

most dye-fiber systems within a defined range as shown in Figure 10. The

reflectance spectrum of the reference standard and the substrate can be measured

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the standard at each wavelength it is possible to calculate the amounts of primaries

needed to obtain the particular shade. In the color matching software, a series of

algorithms are executed to predict the dye recipe with the lowest ΔE CMC value. The

error in color matching process can be reduced by reading the standard and the

sample in the same mode with larger aperture for the spectrophotometer. However,

if the sample does not match the standard close enough, a correction can be applied

to the existing recipe. The correction is calculated on the basis of the color value

difference between the standard and the predicted recipe [36]. The algorithm

iteration then corrects the recipe depending on the deviation of the current recipe

from the reference standard.

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2.7 Need for new primaries

Dyed cationized cotton samples have higher amounts of dye compared to

traditionally dyed samples [37]. However, changes in the (redness-greenness) a*,

(yellowness-blueness) b* and (Chroma) C* and (hue) h values between the treated

and untreated samples have also been reported [38]. A study on color assessment of

cationized cotton reveals that apart from lower L* values, dyed cationized cotton

samples showed a different trend in C* values [39]. The C* tends to level off with

increasing concentration of dye on the cotton samples. However, it was also seen

that the behavior of red dye on cationized cotton was unusual and different than the

rest of the dyes on cationized cotton. This will limit the application of cationized

cotton in the industry due to the change in appearance of shade. Also, the recipes

used for dyeing untreated cotton would not be applicable for cationized cotton.

Hence, it is necessary to develop new primaries for cationized cotton to overcome

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3. Experimental

3.1 Materials

Cotton Inc. supplied greige plain woven fabric rolls of 16kgs each which were used

throughout the experiment. In all, 23 reactive dyes were used along with other

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Table 1: List of Chemical and Auxiliaries

Sr. No Name Use Supplier

1. CR-2000 (65%) CHPTAC

(Cationizing agent)

Dow Chemicals

2. Sodium Hydroxide (50%) NaOH

(Alkali)

Brenntag

3. Sodium sulfate Glauber’s Salt

(Electrolyte)

Brenntag

4. Sodium Carbonate Soda Ash

(Alkali)

Brenntag

5. Carboxymethyl cellulose (size 8) CMC

(Leveling agent)

Rohm & Haas

6. Primasol NB NL Wetting Agent BASF

7. Hydrogen peroxide (35%) H2O2 (Bleaching) Brenntag

8. ApolloScour SRDS Surfactant Apollo

Chemicals

9. Acetic Acid (99.85%) Acid Brenntag

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Table 2: List of Dyes

Sr. No

Product Name C.I. Name Supplier

1. Novacron Yellow F-4G Reactive Yellow 143 Huntsman

2. Novacron Yellow FN-2R Reactive Yellow 206 Huntsman

3. Novacron Yellow C-R Reactive Yellow 168 Huntsman

4. Novacron Red FN-R Reactive Red 238 Huntsman

5. Novacron Red FN-3G Reactive Red 266 Huntsman

6. Novacron Blue FN-R Reactive Blue 235 Huntsman

7. Novacron Brilliant Blue FN-G Reactive Blue 268 Huntsman

8. Novacron Super Black R - Huntsman

9. Novacron Super Black G - Huntsman

10. Remazol Golden Yellow RGB - Dystar

11. Remazol Red RGB - Dystar

12. Remazol Navy RGB (150%) Reactive Blue 250 Dystar

13. Remazol Turquoise G-A Reactive Blue 21 Dystar

14. Drimaren Yellow K-2R Reactive Yellow 125 Clariant

15. Drimaren Red K-4BL Reactive Red 147 Clariant

16. Drimaren Blue K-2RL Reactive Blue 209 Clariant

17. Drimaren Yellow CL-2R Reactive Yellow 176 Clariant

(44)

Table 2 Continued

19. Drimaren Navy CL-R Reactive Black 5 Clariant

20. Drimaren Yellow X-4RN Reactive Orange 70 Clariant

21. Drimaren Red X-6BN Reactive Red 243 Clariant

22. Drimaren Blue X-3LR Reactive Blue 52 Clariant

23. Drimaren Navy X-GN Reactive Blue 214 Clariant

3.2 Equipment

The greige fabric was desized in the laboratory scale Thies jet machine. The

uncationized cotton samples were dyed by the conventional method in Ahiba

Texomat Machine. The cationized cotton samples were dyed in Ahiba Nuance

machine. The samples were measured on an X-rite Colorimeter spectrophotometer

using the Color iContol Software.

3.3 Pretreatment Procedure

Warp size identification on the greige fabric was carried out using the spot test

[40]. The warp size was identified to be polyvinyl alcohol. The fabric was desized

and scoured using 2 g/L of wetting agent and 2 g/L soda ash at 100°C for 2 hrs. The

fabric was then bleached using 6 g/L of H2O2 and 3 g/L of NaOH for 2hrs at 95°C.

(45)

acetic acid to obtain a pH of 5-6. A material to liquor ratio of 1:20 was maintained

during the entire process. The fabric was finally dried.

3.4 Cationization Procedure

Cationization of cotton was carried out using a cold pad batch procedure. Two

rolls of the bleached fabric were cationized with 25 g/L and 50 g/L CHPTAC

treatment. CHPTAC and NaOH were mixed in the ratio of 1: 0.6 and the fabric was

padded with this liquor and batched on rollers for 24hrs. After this treatment, the

fabric was rinsed and neutralized with 0.5 g/L citric acid and dried.

3.5 Dyeing Procedures

Each sample approximately weighed 20g and liquor to material ratio of 20:1 was

maintained for all the dyeing procedures. The uncationized cotton samples (CD

samples) were dyed by the conventional method at 0.25, 1.0 and 4.0 % depth on the

weight of fiber along with the dye manufacturer recommended amount of Glauber’s

(46)

Table 3: Concentration of Glauber’s salt and Soda Ash used in Dyeing Samples

Novacron ( Yellow, Red, Blue) dyes

% Shade 0.25 0.5 1 2 4

Glauber’s salt (g/L) 30 40 50 60 80

Soda Ash (g/L) 8 10 12 14 18

Novacron (Black) dyes

% Shade 0.5 1 2 4 8

Glauber’s salt (g/L) 40 50 60 80 100

Soda Ash (g/L) 10 12 14 18 18

Remazol dyes

% Shade 0.25 0.5 1 2 4

Soda Ash (g/L) 5 6 8 10.4 14

Drimaren K dyes

% Shade 0.25 0.5 1 2 4

(47)

Table 3 Continued

Drimaren CL dyes

% Shade 0.25 0.5 1 2 4

Soda Ash (g/L) 5 10 15 18 20

Drimaren X dyes

% Shade 0.25 0.5 1 2 4

Soda Ash (g/L) 5 8 10 15 20

The cationized cotton samples of 25 g/L (C25 samples) and 50 g/L (C50

samples) were dyed at 0.25, 0.5, 1.0, 2.0 and 4.0 % shades with the recommended

amount of soda ash (Table 3) and without the use of salt.

For Novacron super Black R and Novacron Super Black G 0.5, 2, 8 % shades were

dyed conventionally while the cationized cotton samples were dyed at 0.5, 1, 2, 4

and 8 % shades. 1 g/L of CMC was used as a leveling agent while dyeing cationized

(48)

Table 4: Conventional Dyeing Procedure for Novacron Dyes.

Step Procedure

1 Heat the dyeing bath to 60°C and add the calculated amount of salt and

water.

2 Add the fabric and run the machine for 5 minutes at 60°C.

3 Add the dye and run the machine for 5 minutes at 60°C.

4 Add soda ash and continue to run the machine for 40 minutes (45minutes

for blacks) at 60°C.

5 Cool to 50°C and discard the bath.

6 Rinse the samples with hot water at 70°C and then with cold water at

room temperature.

7 Neutralize the samples using 0.5 g/L acetic acid for 5 minutes and discard

the bath.

8 Add 1 g/L of surfactant and scour the samples for 10 minutes at 95°C.

9 Rinse the samples with cold water.

(49)

Table 5: Conventional Dyeing Procedure for Remazol Dyes.

1 Add the calculated amount of salt and water at room temperature.

2 Add the wet fabric and continue to run for 5 minutes.

3 Add the dye and run for 5 minutes.

4 Add 1/3rd_{the calculated amount of soda ash and run for 10 minutes.}

5 Heat the bath to 60°C at 1°C/min (1.8°F/min) and continue to dye at 60°C

for 10 minutes.

6 Add the 2/3rd_{amount of soda ash and continue to dye at 60°C for 20}

minutes.

room temperature.

the bath.

(50)

Table 6: Conventional Dyeing Procedure for Drimaren K Dyes.

1 Add the calculated amount of salt and water at room temperature.

2 Add the wet fabric and run for 5 minutes.

3 Add the dye and run for 10 minutes.

4 Add soda ash and run for 10 minutes.

5 Heat the bath to 60°C at 1°C/min (1.8°F/min) and continue dyeing for 40

minutes at 60°C.

room temperature.

the bath.

(51)

Table 7: Conventional Dyeing Procedure for Drimaren CL Dyes.

1 Add the calculated amount salt and water at room temperature.

2 Add wet fabric in the bath and run for 5 minutes.

3 Heat to 60°C @ 1°C/min (1.8°F/min)

4 Add the dye and run for 10 minutes at 60°C.

5 Add soda ash and continue to dye for 40 minutes at 60°C.

room temperature.

the bath.

(52)

Table 8: Conventional Dyeing Procedure for Drimaren X Dyes.

1 Add the calculated amount salt and water at room temperature.

2 Add wet fabric in the bath and run for 5 minutes.

3 Heat to 95°C @ 1°C/min (1.8°F/min)

4 Add the dye and run for 10 minutes at 95°C.

5 Add soda ash and continue to dye for 40 minutes at 95°C.

room temperature.

the bath.

(53)

Table 9: Dyeing Procedure for Cationized Cotton samples.

1 Add the calculated amount of water, dye, soda ash and CMC in the beaker.

2 Add the wet fabric and seal the beaker.

3 Heat the chamber to 60°C (95°C for Drimaren X dyes) at 2°C/min.

4 Continue dyeing for 40 minutes (45 minutes for Novacron black dyes) at

60°C.

room temperature.

the bath.

(54)

3.6 Evaluation Procedures

K/Ssum of all the samples was measured where,

K/Ssum = sum of the K/S values over the wavelength from 360 to 750nm.

Spectrophotometer reading conditions:

- Reflectance mode

- Specular condition Included

- Port Diameter = 25 mm

- UV energy Excluded

- Average of 4 readings

- Across the visible spectrum of 360 to 750 nm at 10nm intervals

The formula used for calculating the dye bath exhaustion is:

% E = 1 – (AAD / ABD) X 100, where

AAD = sum of absorbance of the dye bath after the dyeing cycle over the wavelengths

360 to 750 nm.

ABD = sum of absorbance of the dye bath before the dyeing cycle over the wavelength

360 to 750 nm.

AATCC Test method 61-2A was followed to carry out Wash fastness tests [41].

(55)

3.7 Colorant Database Evaluation

Reflectance spectra of CD, C25 and C50 samples dyed using different

concentrations of each colorant were measured on the spectrophotometer and a

new colorant database was created. To formulate a recipe, the standard and the

substrate were read on the spectrophotometer and the three colorants to be used as

primaries were selected. The software predicted the starting recipes using the

conventional and cationized primaries which were then dyed on the cationized

cotton and were compared to the standard on the basis of the ΔE CMC value. The

recipe correction was applied to the samples dyed with Remazol dyes in which the

samples dyed with the predicted recipe was read on the spectrophotometer and the

(56)

4. Results and Discussion

4.1 Dyed Cationized cotton samples

Cationized cotton contains positive charges which attracts the anionic reactive

dyes thus eliminating the use of salt. However, it is seen that dyed cationized cotton

samples tend to have leveling problems. The reason for unlevel dyeing is due to the

strong attraction between the cationic sites on the fiber and the anionic dye which

increases the strike of the dye as soon as it comes in contact with fabric. Hence,

carboxymethyl cellulose (CMC) is commonly used as a leveling agent while dyeing

cationized cotton with anionic dyes. CMC is a negatively charged polymer with acts

as a competitor to the anionic dye for the cationic sites thus reducing the strike of

the dye [7].

The samples obtained by dyeing 25 g/L CHPTAC fabric were level for all %

shades and dyes by visual inspection. However, the 0.25 and 0.5% shades for 50 g/L

CHPTAC samples were unlevel for all the dyes. 50 g/L CHPTAC samples had more

cationic sites available than dye available from the 0.25 and 0.5% shades. Due to

this, even 1 g/L of CMC was not effective to control the high strike of dye and thus

(57)

4.2 Comparison of K/S values

K/Ssum values for all the samples are reported in Tables 10-32 and the plots of

K/Ssum vs. % shade are reported in Figures 11-33. The K/Ssum has been reported for

all the samples in order to incorporate the change in λmax due to change in hue for

the dyed cationized cotton samples. It can be clearly seen from these plots and

tables that the C50 samples have higher K/Ssum compared to the conventionally

dyed samples. More amounts of dye are present on C50 samples than on the CD

samples.

The K/Ssum values for C25 samples are slightly higher or comparable to CD

samples up to 1% shades after which C25 samples have lesser K/Ssum values. C25

samples have lesser number of cationic sites hence, when more amount of dye is

added in the bath there are not enough cationic sites available for the dye to get

exhausted and thus C25 samples have lesser amount of dye on the fabric for %

shades greater than 1%.

The C25 samples achieve an early plateau region due to lesser color yield at

higher % shades compared to CD and C50 samples. The pattern of plot of K/Ssum vs.

% shade is different of each dye. For some dyes the difference in the color yield

between C50 and CD samples is very high and for some dyes this difference is less.

However, the color yield for C50 samples remains higher for all the dyes compared

to the CD and C25 samples. Hence, lesser amount of dye is required to achieve a

(58)

Table 10: K/Ssum values for Reactive Yellow 143

Reactive Yellow 143

%Shade K/S CD λ max CD K/S C25 λ max C25 K/S C50 λ max C50

0.25 6.8 430 13.1 430 31.5 430

0.5 24.1 430 47.7 430

1 23.3 430 37.1 430 86.6 430

2 62.1 430 127.9 430

4 88.4 430 93.4 430 161.8 430

Figure 11: Plot of K/Ssum vs. % Shade for Reactive Yellow 143 0.0

20.0 40.0 60.0 80.0 100.0 120.0 140.0 160.0 180.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Yellow 143

(59)

% Shade K/S CD λ max CD K/S C25 λ max C25 K/S C50 λ max C50

0.25 28.0 435 31.2 430 42.1 430

0.5 48.7 430 77.9 430

1 86.8 435 75.9 430 137.5 430

2 109.7 430 206.7 435

4 228.6 435 151.0 430 268.0 435

Figure 12: Plot of K/Ssum vs. % Shade for Reactive Yellow 206

0.0 50.0 100.0 150.0 200.0 250.0 300.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Yellow 206

CD

C25

(60)

0.25 20.0 415 27.0 415 38.8 415

0.5 42.9 415 70.1 415

1 67.5 415 70.6 415 117.9 415

2 133.3 415 180.4 415

4 200.4 415 162.2 415 241.7 420

50.0 100.0 150.0 200.0 250.0 300.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Yellow 168

(61)

Table 13: K/Ssum values for Reactive Red 238

Reactive Red 238

0.25 19.3 550 21.8 550 39.4 550

0.5 35.5 550 75.7 550

1 61.8 550 56.8 550 132.8 550

2 87.7 550 183.9 550

4 183.9 550 120.4 550 251.7 525

Figure 14: Plot of K/Ssum vs. % Shade for Reactive Red 238 0.0

50.0 100.0 150.0 200.0 250.0 300.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Red 238

(62)

%Shade K/S CD λ max CD K/S C25 λ max C25 K/S C50 λ max C50

0.25 45.9 525 48.8 525 71.5 525

0.5 76.8 525 144.3 520

1 154.6 520 126.6 525 212.4 520

2 190 520 298.1 515

4 311.2 515 243.9 520 364.5 515

50.0 100.0 150.0 200.0 250.0 300.0 350.0 400.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Red 266

(63)

Table 15: K/Ssum values for Reactive Blue 235

Reactive Blue 235

0.25 28.0 625 28.3 625 43.2 625

0.5 52.2 620 75.2 625

1 90.9 625 81.4 620 141.6 625

2 129.9 620 215.3 625

4 279.3 620 192.4 620 315.8 620

Figure 16: Plot of K/Ssum vs. % Shade for Reactive Blue 235 0.0

50.0 100.0 150.0 200.0 250.0 300.0 350.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Blue 235

(64)

0.25 38.8 635 36.1 635 73.3 640

0.5 61.8 635 148.1 640

1 131.2 635 103.1 645 233.4 640

2 162.1 640 325.8 640

4 318.7 635 219.3 635 416.5 640

50.0 100.0 150.0 200.0 250.0 300.0 350.0 400.0 450.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Blue 268

(65)

Table 17: K/Ssum values for Novacron Super Black R

Novacron Super Black R

0.5 90.5 590 100.3 575 184.4 605

1 176.1 570 334.7 585

2 325.1 600 266.5 575 469.8 580

4 402.0 580 626.3 565

8 654.9 565 527.8 580 735.0 560

Figure 18: Plot of K/Ssum vs. % Shade for Novacron Super Black R 0.0

100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0

0 2 4 6 8 10

K

/S

su

m

% Shade

Novacron Super Black R

(66)

Table 18: K/Ssum values for Novacron Super Black G

Novacron Super Black G

0.5 94.0 605 99.8 605 198.6 605

1 157.5 605 319.8 605

2 331.6 605 261.7 605 475.7 610

4 382.7 605 631.2 610

8 677.7 605 475.6 605 715.5 610

Figure 19: Plot of K/Ssum vs. % Shade for Novacron Super Black G 0.0

100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0

0 2 4 6 8 10

K

/S

su

m

% Shade

Novacron Super Black G

(67)

Table 19: K/Ssum values for Remazol Golden Yellow RGB

Remazol Golden Yellow RGB

0.25 15.9 430 17 430 33.6 430

0.5 32.8 430 61.3 430

1 51.6 430 44.7 430 100.1 430

2 70.1 430 166.6 430

4 171.2 425 105.3 430 230.6 425

Figure 20: Plot of K/Ssum vs. % Shade for Remazol Golden Yellow RGB 0.0

50.0 100.0 150.0 200.0 250.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Remazol Golden Yellow RGB

(68)

Table 20: K/Ssum values for Remazol Red RGB

Remazol Red RGB

0.25 18.3 535 21.8 535 43.0 535

0.5 31.6 535 82.9 530

1 61.9 535 51.4 535 121.6 530

2 84 535 191.7 530

4 196.3 530 133.4 535 254.4 525

Figure 21: Plot of K/Ssum vs. % Shade for Remazol Red RGB 0.0

50.0 100.0 150.0 200.0 250.0 300.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Remazol Red RGB

(69)

0.25 29.1 615 35.9 615 47.1 615

0.5 55.3 615 103.7 615

1 103.9 615 98.3 615 185.4 615

2 167.8 610 302.5 610

4 355.4 610 271 610 441.8 610

Figure 22: Plot of K/Ssum vs. % Shade for Reactive Blue 250 0.0 50.0 100.0 150.0 200.0 250.0 300.0 350.0 400.0 450.0 500.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Blue 250

(70)

0.25 13.8 675 17.1 675 29.0 675

0.5 28.8 675 60.8 675

1 43.3 675 52.1 675 124.0 675

2 71.9 675 203.7 675

4 150.8 675 118.7 675 295.6 675

50.0 100.0 150.0 200.0 250.0 300.0 350.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Blue 21

(71)

0.25 24.5 420 37.9 420 41.4 425

0.5 48.7 420 85.2 425

1 85.9 420 85.2 415 143.9 425

2 144.5 420 234.8 420

4 229.9 420 196.7 415 293.4 420

50.0 100.0 150.0 200.0 250.0 300.0 350.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Yellow 125

(72)

0.25 17.1 550 18.9 545 32.3 550

0.5 32.5 550 66.2 550

1 58.0 550 45 545 110.3 550

2 86.4 545 185.4 550

4 192.1 550 142.8 545 245.5 550

50.0 100.0 150.0 200.0 250.0 300.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Red 147

(73)

0.25 21.8 630 27.7 630 35.5 630

0.5 48.3 625 64.2 630

1 78.1 630 82.5 625 139.1 630

2 133.6 625 239.9 630

4 254.4 625 229.2 625 363.0 625

50.0 100.0 150.0 200.0 250.0 300.0 350.0 400.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Blue 209

(74)

0.25 19.8 435 24.1 425 50.7 435

0.5 40.7 425 85.8 435

1 64.7 435 64.2 425 134.2 435

2 96.4 430 194.5 430

4 156.3 435 131.0 430 250.5 430

50.0 100.0 150.0 200.0 250.0 300.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Yellow 176

(75)

0.25 18.6 550 20.6 550 34.0 550

0.5 35.9 550 67.0 550

1 69.2 550 55.2 550 123.2 550

2 94.5 550 184.5 550

4 192.0 550 138.4 550 251.2 550

50.0 100.0 150.0 200.0 250.0 300.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Red 197

(76)

Table 28: K/Ssum values for Reactive Black 5

Reactive Black 5

0.25 46.1 605 45.9 605 102.1 605

0.5 87.2 605 172.6 605

1 172.1 605 144.3 605 277.0 610

2 247.1 605 405.2 605

4 482.7 610 371.1 605 542.2 580

Figure 29: Plot of K/Ssum vs. % Shade for Reactive Black 5 0.0

100.0 200.0 300.0 400.0 500.0 600.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Black 5

(77)

Table 29: K/Ssum values for Reactive Orange 70

Reactive Orange 70

0.25 19.4 440 22.5 425 34.1 435

0.5 37.4 430 68.9 435

1 72.0 435 62.8 430 113.3 435

2 103.1 425 188.9 435

4 217.6 435 161.7 425 265.9 435

Figure 30: Plot of K/Ssum vs. % Shade for Reactive Orange 70 0.0

50.0 100.0 150.0 200.0 250.0 300.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Orange 70

(78)

0.25 18.4 555 28.9 555 42.5 555

0.5 47.8 555 80.7 555

1 64.4 555 77.2 555 133.0 555

2 121.4 555 209.0 555

4 226.9 555 179.1 555 282.2 555

50.0 100.0 150.0 200.0 250.0 300.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Red 243

(79)

0.25 16.6 630 34.3 630 43.2 630

0.5 50.2 630 80.0 630

1 65.2 630 63 630 135.4 630

2 101.7 630 229.3 630

4 236.3 630 150.3 625 342.7 630

50.0 100.0 150.0 200.0 250.0 300.0 350.0 400.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Blue 52

CD

C 25

(80)

0.25 22.2 620 28.3 615 53.6 615

0.5 49 615 100.5 615

1 79.0 615 86.4 615 159.2 615

2 164.5 615 254.3 610

4 294.7 615 253 615 366.9 610

50.0 100.0 150.0 200.0 250.0 300.0 350.0 400.0

0 1 2 3 4 5

K

/S

su

m

% Shade

Reactive Blue 214

(81)

4.3 Comparison of L*, a* and b* values

Table 33 compares the L*, a* and b* values for all the samples. For a particular

dye and shade, the L*, a* and b* values are different for C50 and C25 samples when

compared to the corresponding CD samples. For instance, considering the Reactive

Red 266 dye at 4% shade, for the CD sample L*= 38.4, a*= 54.12, b*= 26.28, for the

C25 sample L*= 42.43, a*= 57.41, b*= 27.02 and for C50 sample L*= 39.07, a*=

56.04, b*= 31.72. The C25 sample above is lighter, redder and bluer while the C50

sample is darker, greener and yellower compared to the CD sample. These

differences are observed for all the shades and dyes. This restricts the use of the

recipes from existing conventional primaries on cationized cotton since the shades

obtained on cationized cotton will be different than that on untreated cotton. Also, it

(82)

Table 33: L*, a*, b* values of CD, C25 and C50 samples

Dye % Shade Sample L* a* b*

Reactive Yellow 143

0.25

CD 93.42 -7.26 44.48

C25 91.25 -7.25 54.61

C50 89.01 -7.09 69.49

1

CD 91.01 -6.05 67.38

C25 88.63 -5.25 73.67

C50 85.2 -2.39 85.4

4

CD 87.31 -0.93 90.36

C25 85.46 -0.49 88.48

C50 82.9 4.36 95.58

Reactive Yellow 206

0.25

CD 82.63 17.3 58.12

C25 81.56 15.9 58.48

C50 80.27 17.45 63.25

1

CD 75.19 29.57 73.7

C25 75.03 24.3 69.31

C50 71.7 31.5 77.33

4

CD 66.87 41.5 79.93

C25 68.42 30.34 73.49

(83)

Table 33 Continued

Reactive Yellow 168

0.25

CD 86.64 8.56 53.54

C25 84.6 9.04 56.61

C50 83.6 11.55 64.45

1

CD 80.22 19.12 72.59

C25 78.46 18.14 69.69

C50 76.04 22.95 78.61

4

CD 72 30.89 83.87

C25 71 26.38 76.79

C50 67.3 32.76 79.96

Reactive Red 238

0.25

CD 65.06 42.07 -7.96

C25 63.53 45.83 -8.37

C50 57.54 53.57 -7.56

1

CD 51.48 53.46 -5.96

C25 53.08 55.28 -6.1

C50 45.14 60.6 0.58

4

CD 39.83 57.1 0.92

C25 44.99 58.53 -1.74

(84)

Table 33 Continued

Reactive Red 266

0.25

CD 59.12 50.32 12.76

C25 59.19 52.08 14.21

C50 56.84 56.55 19.15

1

CD 46.3 56.15 21.6

C25 49.75 57.86 22.45

C50 45.62 58.66 28.93

4

CD 38.4 54.12 26.28

C25 42.43 57.41 27.02

C50 39.07 56.04 31.72

Reactive Blue 235

0.25

CD 60.09 -3.76 -23.12

C25 59.86 -4.54 -23.45

C50 54.45 -3.55 -29.18

1

CD 43.65 -2.27 -28.82

C25 45.13 -3.2 -27.57

C50 37.59 0.58 -32.35

4

CD 27.93 2.78 -28.8

C25 33.14 -0.63 -28.35

(85)

Table 33 Continued

Reactive Blue 268

0.25

CD 59.85 -10.69 -33.24

C25 60.78 -11.68 -31.88

C50 54.69 -14.35 -36.98

1

CD 44.45 -6.7 -39.77

C25 48.98 -10.59 -36.67

C50 38.15 -4.89 -40.95

4

CD 31.13 2.18 -40.29

C25 37.21 -3.4 -38.52

C50 27.64 2.55 -37.46

Novacron super

Black R

0.5

CD 41.22 1.05 -4.5

C25 39.45 3.17 -3.68

C50 30.86 0.2 -6.71

2

CD 23.73 1.78 -2.88

C25 25.98 3.25 -3

C50 19.58 2.01 -2.16

8

CD 16.5 1.25 -1.11

C25 18.22 1.95 -2.36

(86)

Table 33 Continued

Novacron super

Black G

0.5

CD 41.61 -3.97 -2.96

C25 40.78 -3.84 -1.82

C50 30.7 -4.16 -4.46

2

CD 24.2 -2.42 -2.14

C25 27.22 -2.77 -1.74

C50 20.03 -1.36 -1.39

8

CD 16.44 -0.05 -0.82

C25 19.85 -1.73 -2.57

C50 15.94 0.29 -0.42

Remazol Golden

Yellow RGB

0.25

CD 85.1 12 48.4

C25 84.34 10.95 48.7

C50 81.66 16.24 61.59

1

CD 77.54 22.72 65.31

C25 77.84 20.04 61.82

C50 73.97 27.4 75.07

4

CD 68.17 34.22 76.89

C25 70.68 28.2 70.63

(87)

Table 33 Continued

Remazol Red RGB

0.25

CD 65.97 42.81 -5.67

C25 63.93 44.89 -5.96

C50 57.2 54.52 -5.55

1

CD 52.48 54.96 -2.81

C25 54.31 53.05 -3.82

C50 46.16 59.42 1.26

4

CD 40.65 58.67 5.12

C25 44.61 58.79 1.71

C50 38.17 57.47 9.1

Reactive Blue 250

0.25

CD 59.45 -10.14 -14.56

C25 56.33 -10.71 -16.1

C50 52.94 -12.03 -18.4

1

CD 41.4 -10.83 -17.64

C25 42.03 -10.76 -17.95

C50 33.23 -9.36 -18.53

4

CD 24.02 -5.95 -14.32

C25 27.75 -7.64 -16.21