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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
The The "direct dye""direct dye" classification in the Color Index system classification in the Color Index system refers to various planar, highly conjugated molecular refers to various planar, highly conjugated molecular structures that also contain one or more anionic structures that also contain one or more anionic sulphonate group. It is because of these sulphonate sulphonate group. It is because of these sulphonate groups that the molecules are soluble in water. groups that the molecules are soluble in water.
The The "direct dye""direct dye" classification in the Color Index system classification in the Color Index system refers to various planar, highly conjugated molecular refers to various planar, highly conjugated molecular structures that also contain one or more anionic structures that also contain one or more anionic sulphonate group. It is because of these sulphonate sulphonate group. It is because of these sulphonate groups that the molecules are soluble in water. groups that the molecules are soluble in water.
Direct dyesDirect dyes - dyes with a high affinity for cellulose - dyes with a high affinity for cellulose fibresfibres
Substantive dyesSubstantive dyes are dyes used in a process in which are dyes used in a process in which dye molecules are attracted by physical forces at the dye molecules are attracted by physical forces at the molecular level to the textile substrates. The amount of molecular level to the textile substrates. The amount of this attraction is known as this attraction is known as substantivitysubstantivity
Direct dyesDirect dyes - dyes with a high affinity for cellulose - dyes with a high affinity for cellulose fibresfibres
Substantive dyesSubstantive dyes are dyes used in a process in which are dyes used in a process in which dye molecules are attracted by physical forces at the dye molecules are attracted by physical forces at the molecular level to the textile substrates. The amount of molecular level to the textile substrates. The amount of this attraction is known as this attraction is known as substantivitysubstantivity
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Congo redCongo red is the sodium salt of benzidinediazo-bis-1- is the sodium salt of benzidinediazo-bis-1-naphthylamine-4-sulfonic acid (formulanaphthylamine-4-sulfonic acid (formula C C3232HH2222NN66NaNa22OO66SS22, , : molecular weight: 696.66 g/mol ): molecular weight: 696.66 g/mol ) brownish-red brownish-red powder, powder,
Congo redCongo red is the sodium salt of benzidinediazo-bis-1- is the sodium salt of benzidinediazo-bis-1-naphthylamine-4-sulfonic acid (formulanaphthylamine-4-sulfonic acid (formula C C3232HH2222NN66NaNa22OO66SS22, , : molecular weight: 696.66 g/mol ): molecular weight: 696.66 g/mol ) brownish-red brownish-red powder, powder,
Congo RedCongo Red (Colour Index(Colour Index, , No. 370), was the first No. 370), was the first member of the direct cotton group of dyes. member of the direct cotton group of dyes.
Patented by Paul Böttiger's (Friedrich Bayer Company in Patented by Paul Böttiger's (Friedrich Bayer Company in Elberfeld, Germany ) B.P. 4,416 of 1884Elberfeld, Germany ) B.P. 4,416 of 1884
Congo RedCongo Red (Colour Index(Colour Index, , No. 370), was the first No. 370), was the first member of the direct cotton group of dyes. member of the direct cotton group of dyes.
Patented by Paul Böttiger's (Friedrich Bayer Company in Patented by Paul Böttiger's (Friedrich Bayer Company in Elberfeld, Germany ) B.P. 4,416 of 1884Elberfeld, Germany ) B.P. 4,416 of 1884x
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
10.8Å
Cellulose - Cellobiose
Benzedrine
Hydrogen Bonding of Cellulose dyed with Congo Red
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Benzopurpurine 4BBenzopurpurine 4B Benzopurpurine 4BBenzopurpurine 4B
Second Second Direct DyeDirect DyeSecond Second Direct DyeDirect Dye
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Benzedrine Benzedrine ReplacementReplacementBenzedrine Benzedrine ReplacementReplacement
4,4’ - diaminobenzanilide4,4’ - diaminobenzanilide4,4’ - diaminobenzanilide4,4’ - diaminobenzanilide
C.I. Direct Black 166C.I. Direct Black 166
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
2,2'-dimethyl-5,5'- dipropoxybenzidine 2,2'-dimethyl-5,5'- dipropoxybenzidine is non-mutagenicis non-mutagenic
2,2'-dimethyl-5,5'- dipropoxybenzidine 2,2'-dimethyl-5,5'- dipropoxybenzidine is non-mutagenicis non-mutagenic
Synthesis and Evaluation of Non-genotoxic Direct Synthesis and Evaluation of Non-genotoxic Direct Dyes, Jin-Seok Bae* and Harold S. Freeman, Dyes, Jin-Seok Bae* and Harold S. Freeman, fibres fibres and Polymers and Polymers 2002, Vol.3, No.4, 140-1462002, Vol.3, No.4, 140-146
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
C.I. Direct C.I. Direct Yellow 59Yellow 59C.I. Direct C.I. Direct Yellow 59Yellow 59
Phenyalbenzothiazole GroupPhenyalbenzothiazole GroupPhenyalbenzothiazole GroupPhenyalbenzothiazole Group
Yellow substantive dyesYellow substantive dyes
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
C.I. Direct C.I. Direct Green 28Green 28C.I. Direct C.I. Direct Green 28Green 28
Blue Yellow
Non-substantive anthrquinone based blue dye is Non-substantive anthrquinone based blue dye is attached to substantive monoazo yellow dye via triazine attached to substantive monoazo yellow dye via triazine molecule to get green dyemolecule to get green dye
Non-substantive anthrquinone based blue dye is Non-substantive anthrquinone based blue dye is attached to substantive monoazo yellow dye via triazine attached to substantive monoazo yellow dye via triazine molecule to get green dyemolecule to get green dye
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
C.I. Direct C.I. Direct Yellow 12Yellow 12
Chrysophenine GChrysophenine GChrysophenine GChrysophenine G
Stilbene and azo chromophore: Stilbene and azo chromophore: Dyeable on cotton, wool and silkDyeable on cotton, wool and silk
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
PhthalocyaninePhthalocyanine
Direct DyesDirect Dyes
PhthalocyaninePhthalocyanine
Direct DyesDirect Dyes
Water soluble Water soluble
sodium salts of sodium salts of
sulphonated sulphonated
copper copper
phthalocyaninephthalocyanine
Water soluble Water soluble
sodium salts of sodium salts of
sulphonated sulphonated
copper copper
phthalocyaninephthalocyanine
Turquoise Blue shadesTurquoise Blue shadesTurquoise Blue shadesTurquoise Blue shades
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Chemical Chemical ClassClass YELYEL ORGORG REDRED VIOVIO BLUBLU GREGRE BRBR BLBL %%
MonoazoMonoazo 44 77 1414 44 -- 88 33 55
DisazoDisazo 5858 5353 7171 8383 5252 2121 2222 2323 4949
PolyazoPolyazo 88 1616 1010 33 3131 6464 6767 6868 3333
Cu-Cu-ComplexComplex -- -- 33 99 1212 44 11 88 55
StilbeneStilbene 1717 2323 22 -- -- -- -- -- 55
ThiazoleThiazole 1313 11 -- -- -- -- -- -- 11
DioxazineDioxazine -- -- -- 11 33 -- -- -- 11
Phthalo-Phthalo-
cyaninecyanine-- -- -- -- 22 22 -- -- 11
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Reactant Fixable Reactant Fixable DyesDyesReactant Fixable Reactant Fixable DyesDyes
Indosol SF dyes of Clariant have been one of the Indosol SF dyes of Clariant have been one of the major developmentmajor development
Original range had 12 copper complex dyes: C.I. Original range had 12 copper complex dyes: C.I. Direct Violet 66Direct Violet 66
Indosol CR is the special dye fixing agent: N-Indosol CR is the special dye fixing agent: N-methylol dicyandiamide methylol dicyandiamide
Indosol SF dyes of Clariant have been one of the Indosol SF dyes of Clariant have been one of the major developmentmajor development
Original range had 12 copper complex dyes: C.I. Original range had 12 copper complex dyes: C.I. Direct Violet 66Direct Violet 66
Indosol CR is the special dye fixing agent: N-Indosol CR is the special dye fixing agent: N-methylol dicyandiamide methylol dicyandiamide
C.I. Direct Violet 66
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Dyeing Cycle of a Direct DyeDyeing Cycle of a Direct Dye
SorptionStage
Diffusion and
MigrationStage
CoolingStage
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Classification of Direct Classification of Direct DyesDyes
Classification of Direct Classification of Direct DyesDyes
Class AClass A - dyes that can be dyed with out salt and - dyes that can be dyed with out salt and have good migration and levelling propertieshave good migration and levelling propertiesClass AClass A - dyes that can be dyed with out salt and - dyes that can be dyed with out salt and have good migration and levelling propertieshave good migration and levelling properties
Class B Class B – dyes have a low rate of exhaustion and – dyes have a low rate of exhaustion and the rate of exhaustion may be adequately the rate of exhaustion may be adequately controlled by carefully regulated addition of controlled by carefully regulated addition of common salt.common salt.
Class B Class B – dyes have a low rate of exhaustion and – dyes have a low rate of exhaustion and the rate of exhaustion may be adequately the rate of exhaustion may be adequately controlled by carefully regulated addition of controlled by carefully regulated addition of common salt.common salt.
Class C Class C – dyes that are highly sensitive to salt, and – dyes that are highly sensitive to salt, and temperature. These are temperature – controlable temperature. These are temperature – controlable dyesdyes
Class C Class C – dyes that are highly sensitive to salt, and – dyes that are highly sensitive to salt, and temperature. These are temperature – controlable temperature. These are temperature – controlable dyesdyes
500C500C
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Log (Time of Dyeing) Sec
Dye-b
ath
exhaust
ion %
500C500C
900C
900C
Time, min Effect of Effect of TemperatureTemperature
Temperature Temperature increasesincreasesthe rate of the rate of diffusion of diffusion of dyes in the dyes in the fibrefibre
Temperature Temperature increasesincreasesthe rate of the rate of diffusion of diffusion of dyes in the dyes in the fibrefibre
Temperature Temperature lowerslowersthe the equilibrium equilibrium dye uptake of dye uptake of the fibrethe fibre
Temperature Temperature lowerslowersthe the equilibrium equilibrium dye uptake of dye uptake of the fibrethe fibre
Dye - X
Dye - Y
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct DyesD
ye-b
ath
exhaust
ion %
Time, min
3%3%
1%
0%
Gla
uber’
s Salt
Effect of Effect of SaltSaltEffect of Effect of SaltSalt
Salt Sensitive dye Salt Sensitive dye
Durazol Fast Blue Durazol Fast Blue 4GS4GS
Salt Sensitive dye Salt Sensitive dye
Durazol Fast Blue Durazol Fast Blue 4GS4GS
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
-
-
-
-
-
-
-
-
100Å
- +++++++++++
4Å
Dye Dye ionsions
AffinityAffinity
Electrostatic Electrostatic RepulsionRepulsion
Effect of Effect of SaltSaltEffect of Effect of SaltSalt
Sodium Sodium IonsIons
DyebathDyebathDyebathDyebath
FabricFabric
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Adsorption of direct dyes on cellulosic Adsorption of direct dyes on cellulosic
fibres is influenced by the nature of the fibres is influenced by the nature of the
cation in dyebaths containing the alkali cation in dyebaths containing the alkali
chlorides in equimolar concentrations, the chlorides in equimolar concentrations, the
extent of dye adsorption increasing extent of dye adsorption increasing
markedly in the order Li' < Na' < K' < Rb' markedly in the order Li' < Na' < K' < Rb'
< Cs'.< Cs'.
Adsorption of direct dyes on cellulosic Adsorption of direct dyes on cellulosic
fibres is influenced by the nature of the fibres is influenced by the nature of the
cation in dyebaths containing the alkali cation in dyebaths containing the alkali
chlorides in equimolar concentrations, the chlorides in equimolar concentrations, the
extent of dye adsorption increasing extent of dye adsorption increasing
markedly in the order Li' < Na' < K' < Rb' markedly in the order Li' < Na' < K' < Rb'
< Cs'.< Cs'.
Effect of Effect of ElectrolytesElectrolytesEffect of Effect of ElectrolytesElectrolytes
Sivaraja lyer, Srinivasan and Baddi, Text. Research J., 38 (1968) 693Sivaraja lyer, Srinivasan and Baddi, Text. Research J., 38 (1968) 693
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Bio-salt trisodium citrate in the Bio-salt trisodium citrate in the dyeing of cottondyeing of cotton
Bio-salt trisodium citrate in the Bio-salt trisodium citrate in the dyeing of cottondyeing of cotton
Direct Dye Direct Dye dyed with dyed with sod. chloridesod. chloride
Direct Dye Direct Dye dyed with dyed with trisodium trisodium citratecitrate
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Bio-salt trisodium citrate in the Bio-salt trisodium citrate in the dyeing of cottondyeing of cotton
Bio-salt trisodium citrate in the Bio-salt trisodium citrate in the dyeing of cottondyeing of cotton
Sodium ChlorideSodium Chloride Trisodium citrateTrisodium citrate
DyeDye TDSTDS Dye Dye uptakeuptake TDSTDS Dye Dye
uptakeuptake
ReactiveReactive 3480034800 66.766.7 1230012300 89.189.1
DirectDirect 38003800 58.258.2 20002000 76.876.8
S. VatS. Vat 69006900 62.762.7 40004000 83.883.8
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
PretreatmentPretreatmentNo salt DyeingNo salt Dyeing
Treatment of cotton Treatment of cotton with cationic agents with cationic agents introduces positively introduces positively charged group. These charged group. These cationic groups form cationic groups form electrovalent bonds electrovalent bonds with the anionic dyes with the anionic dyes such as Direct and such as Direct and Reactive Dyes.Reactive Dyes. There There by eliminate the need by eliminate the need of salt during dyeingof salt during dyeing
Treatment of cotton Treatment of cotton with cationic agents with cationic agents introduces positively introduces positively charged group. These charged group. These cationic groups form cationic groups form electrovalent bonds electrovalent bonds with the anionic dyes with the anionic dyes such as Direct and such as Direct and Reactive Dyes.Reactive Dyes. There There by eliminate the need by eliminate the need of salt during dyeingof salt during dyeing
Polyepichlorohydrin dimethyl Polyepichlorohydrin dimethyl amine (PECH-amine) is prepared amine (PECH-amine) is prepared bu initial polymerization of of bu initial polymerization of of epichlorohydrin, followed by epichlorohydrin, followed by amination with diamineamination with diamine
Polyepichlorohydrin dimethyl Polyepichlorohydrin dimethyl amine (PECH-amine) is prepared amine (PECH-amine) is prepared bu initial polymerization of of bu initial polymerization of of epichlorohydrin, followed by epichlorohydrin, followed by amination with diamineamination with diamine
Polyepichlorohydrin dimethyl Polyepichlorohydrin dimethyl amine (PECH-amine)amine (PECH-amine)
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
PretreatmentPretreatmentNo salt DyeingNo salt Dyeing
Chitosan Chitosan derivative having derivative having a fibre-reactive a fibre-reactive group, namely group, namely OO--crylamidomethyl-crylamidomethyl-NN-[(2-hydroxy-3--[(2-hydroxy-3-trimethyl trimethyl ammonium)ammonium)propyl] chitosan propyl] chitosan chloride (NMA-chloride (NMA-HTCCHTCC
This compound This compound when applied to when applied to cotton under cotton under alkalinealkalineconditions and is conditions and is able to form a able to form a covalent bond covalent bond with thewith thefibre giving it fibre giving it good durability good durability as anas anantimicrobial antimicrobial textile finishtextile finish
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Fixation of Fixation of Direct DyesDirect Dyes
Mostly cation-active compounds are used as Mostly cation-active compounds are used as the fixation the fixation chemicals. These compounds form a complex of high chemicals. These compounds form a complex of high molecular weight and low aqueous solubility with the dye molecular weight and low aqueous solubility with the dye resulting in high wet fastness of dyed fabricsresulting in high wet fastness of dyed fabrics
CC+ + + D+ D- - = CD= CDAmines, quaternary ammonium, phosphonium and tertiary Amines, quaternary ammonium, phosphonium and tertiary sulphonium compounds can be used as dye fixing agents. sulphonium compounds can be used as dye fixing agents. By far the most important type of cationic fixing agents By far the most important type of cationic fixing agents used in textile processing is quaternary ammonium saltused in textile processing is quaternary ammonium salt
Mostly cation-active compounds are used as Mostly cation-active compounds are used as the fixation the fixation chemicals. These compounds form a complex of high chemicals. These compounds form a complex of high molecular weight and low aqueous solubility with the dye molecular weight and low aqueous solubility with the dye resulting in high wet fastness of dyed fabricsresulting in high wet fastness of dyed fabrics
CC+ + + D+ D- - = CD= CDAmines, quaternary ammonium, phosphonium and tertiary Amines, quaternary ammonium, phosphonium and tertiary sulphonium compounds can be used as dye fixing agents. sulphonium compounds can be used as dye fixing agents. By far the most important type of cationic fixing agents By far the most important type of cationic fixing agents used in textile processing is quaternary ammonium saltused in textile processing is quaternary ammonium salt
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Fixation of Fixation of Direct DyesDirect Dyes
CyanamideCyanamide
Fibrofix – Fibrofix – Cyanamide Cyanamide condensation condensation productproduct
Formaldehyde Formaldehyde condensation condensation product of product of dicyandiamidedicyandiamide
Formaldehyde Formaldehyde condensation condensation product of product of dicyandiamidedicyandiamide
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
PretreatmentPretreatmentNo salt DyeingNo salt Dyeing
Azetidinium chlorideAzetidinium chloride
1,1-diethyl-3-hydroxy 1,1-diethyl-3-hydroxy azetidinium chlorideazetidinium chloride
Sandene 8425Sandene 8425 (Clariant) (Clariant)
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
PretreatmentPretreatmentNo salt DyeingNo salt Dyeing
Phenyl MonochlorotriazinePhenyl Monochlorotriazine Based compoundBased compound
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
All dyes have a tendency to associate in aqueous solution. All dyes have a tendency to associate in aqueous solution.
An understanding of the association of dyes in water is of An understanding of the association of dyes in water is of
importance in both thermodynamic and kinetic studies of importance in both thermodynamic and kinetic studies of
dyeing systems since almost all textile dyes are applied dyeing systems since almost all textile dyes are applied
from aqueous systemsfrom aqueous systems.
All dyes have a tendency to associate in aqueous solution. All dyes have a tendency to associate in aqueous solution.
An understanding of the association of dyes in water is of An understanding of the association of dyes in water is of
importance in both thermodynamic and kinetic studies of importance in both thermodynamic and kinetic studies of
dyeing systems since almost all textile dyes are applied dyeing systems since almost all textile dyes are applied
from aqueous systemsfrom aqueous systems.
Mechanism of DyeingMechanism of DyeingAggregationAggregation
One can study the aggregation behaviour of dyes in One can study the aggregation behaviour of dyes in
solution by spectrophotometric analysis since dye solution by spectrophotometric analysis since dye
aggregates normally have a lower extinction coefficient aggregates normally have a lower extinction coefficient
and their maximum absorbance is at shorter wavelengths and their maximum absorbance is at shorter wavelengths
compared to the monomolecular species with some compared to the monomolecular species with some
exceptionsexceptions
One can study the aggregation behaviour of dyes in One can study the aggregation behaviour of dyes in
solution by spectrophotometric analysis since dye solution by spectrophotometric analysis since dye
aggregates normally have a lower extinction coefficient aggregates normally have a lower extinction coefficient
and their maximum absorbance is at shorter wavelengths and their maximum absorbance is at shorter wavelengths
compared to the monomolecular species with some compared to the monomolecular species with some
exceptionsexceptions
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Mechanism of DyeingMechanism of DyeingAggregationAggregation
Dye*
Dye + Surfactant
Dye + Salt
Wavelength, nm
Abso
rbance
Promotes Promotes AggregationAggregationPromotes Promotes AggregationAggregation
Promotes Promotes AggregationAggregationPromotes Promotes AggregationAggregation
*CI Direct Yellow 162
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Initially it was suggested that hydrogen bonds are Initially it was suggested that hydrogen bonds are
responsible for the association of direct dyes. However responsible for the association of direct dyes. However
layer studies suggest that the the aggregating forces are layer studies suggest that the the aggregating forces are
of the van der Waals’ type of the van der Waals’ type , , including dipole-dipole (and including dipole-dipole (and
induced dipole) forces and particularly dispersion forces, induced dipole) forces and particularly dispersion forces,
which are active over large numbers of planar-stacked which are active over large numbers of planar-stacked
molecules.molecules.
Initially it was suggested that hydrogen bonds are Initially it was suggested that hydrogen bonds are
responsible for the association of direct dyes. However responsible for the association of direct dyes. However
layer studies suggest that the the aggregating forces are layer studies suggest that the the aggregating forces are
of the van der Waals’ type of the van der Waals’ type , , including dipole-dipole (and including dipole-dipole (and
induced dipole) forces and particularly dispersion forces, induced dipole) forces and particularly dispersion forces,
which are active over large numbers of planar-stacked which are active over large numbers of planar-stacked
molecules.molecules.
Mechanism of DyeingMechanism of DyeingAggregationAggregation
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Mechanism of Mechanism of DyeingDyeing
AggregationAggregation
Aggregated direct Aggregated direct dye with ionized salt dye with ionized salt is aqueous solutionis aqueous solution
Aggregated direct Aggregated direct dye with ionized salt dye with ionized salt is aqueous solutionis aqueous solution
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Cotton is a hydrophilic natural cellulose fibre whose porous Cotton is a hydrophilic natural cellulose fibre whose porous
structure facilitates the penetration of various solutes, structure facilitates the penetration of various solutes,
including organic dyes. As a cellulose-based polymer, it including organic dyes. As a cellulose-based polymer, it
consists of D-glucose units joined by b-1,4-glycosidic consists of D-glucose units joined by b-1,4-glycosidic
linkages, and it is well known that the cellulose chains linkages, and it is well known that the cellulose chains
associate with one another via intermolecular hydrogen associate with one another via intermolecular hydrogen
bonds. The resultant system of polymer chains coalesces to bonds. The resultant system of polymer chains coalesces to
form microfibrils that are organized into macrofibrils and form microfibrils that are organized into macrofibrils and
subsequently into fibres.subsequently into fibres.
Cotton is a hydrophilic natural cellulose fibre whose porous Cotton is a hydrophilic natural cellulose fibre whose porous
structure facilitates the penetration of various solutes, structure facilitates the penetration of various solutes,
including organic dyes. As a cellulose-based polymer, it including organic dyes. As a cellulose-based polymer, it
consists of D-glucose units joined by b-1,4-glycosidic consists of D-glucose units joined by b-1,4-glycosidic
linkages, and it is well known that the cellulose chains linkages, and it is well known that the cellulose chains
associate with one another via intermolecular hydrogen associate with one another via intermolecular hydrogen
bonds. The resultant system of polymer chains coalesces to bonds. The resultant system of polymer chains coalesces to
form microfibrils that are organized into macrofibrils and form microfibrils that are organized into macrofibrils and
subsequently into fibres.subsequently into fibres.
Mechanism of DyeingMechanism of DyeingStructure of CottonStructure of Cotton
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Lumen
Reversal
S3
S2
20-30
S1
20-35
Primary Wall
Cuticle
Pectin
Wax
Fats
Crystalline fibrils
Macro Structure Macro Structure of Cottonof Cotton
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Micro Structure Micro Structure of Cottonof Cotton
FibrilFibril
FibrilFibril
FibrilFibril
FibrilFibril
PorePore
PorePore
PorePore
PorePore
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
MechanismMechanismof Dyeingof Dyeing
Diffusion Diffusion of Dyesof Dyes
Static PoreStatic Pore
Model of Dye Model of Dye DiffusionDiffusion
Static PoreStatic Pore
Model of Dye Model of Dye DiffusionDiffusion
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INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Direct dyes are absorbed on the internal surface of Direct dyes are absorbed on the internal surface of
cellulosic substrates, the amount of surface cellulosic substrates, the amount of surface
accessible to a dye anion depending on the form accessible to a dye anion depending on the form
and size of the anion. The internal surface of the and size of the anion. The internal surface of the
fibre also possesses an electric charge. The extent fibre also possesses an electric charge. The extent
to which this initial charge is reinforced depends on to which this initial charge is reinforced depends on
the different absorption of the dye anions by the different absorption of the dye anions by
different surfaces. Besides competition for dye different surfaces. Besides competition for dye
sites, a mutual electrostatic repulsion occurs.sites, a mutual electrostatic repulsion occurs.
Direct dyes are absorbed on the internal surface of Direct dyes are absorbed on the internal surface of
cellulosic substrates, the amount of surface cellulosic substrates, the amount of surface
accessible to a dye anion depending on the form accessible to a dye anion depending on the form
and size of the anion. The internal surface of the and size of the anion. The internal surface of the
fibre also possesses an electric charge. The extent fibre also possesses an electric charge. The extent
to which this initial charge is reinforced depends on to which this initial charge is reinforced depends on
the different absorption of the dye anions by the different absorption of the dye anions by
different surfaces. Besides competition for dye different surfaces. Besides competition for dye
sites, a mutual electrostatic repulsion occurs.sites, a mutual electrostatic repulsion occurs.
Mechanism of DyeingMechanism of DyeingSorption on Internal SurfaceSorption on Internal Surface
Slide 37 of 40
INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
It is known that the accessible area on cellulosic It is known that the accessible area on cellulosic
substrates is a function of the molecule size. substrates is a function of the molecule size.
Recent research has shown that the accessible Recent research has shown that the accessible
volume of a cellulosic fibre for a molecule with volume of a cellulosic fibre for a molecule with
an effective diameter of 2.5 nm was about four an effective diameter of 2.5 nm was about four
times higher than that for a molecule with an times higher than that for a molecule with an
effective diameter of 5 nmeffective diameter of 5 nm
It is known that the accessible area on cellulosic It is known that the accessible area on cellulosic
substrates is a function of the molecule size. substrates is a function of the molecule size.
Recent research has shown that the accessible Recent research has shown that the accessible
volume of a cellulosic fibre for a molecule with volume of a cellulosic fibre for a molecule with
an effective diameter of 2.5 nm was about four an effective diameter of 2.5 nm was about four
times higher than that for a molecule with an times higher than that for a molecule with an
effective diameter of 5 nmeffective diameter of 5 nm
Mechanism of DyeingMechanism of DyeingSorption on Internal SurfaceSorption on Internal Surface
Slide 38 of 40
INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
Mechanism of DyeingMechanism of DyeingVoid Size and AreaVoid Size and Area
Viscose RayonViscose RayonViscose RayonViscose Rayon Modal FibresModal FibresModal FibresModal Fibres Lyocell FibresLyocell FibresLyocell FibresLyocell Fibres
Lyocell fibres consist of longer molecules, they have a Lyocell fibres consist of longer molecules, they have a greater degree of crystallinity, its crystallites are oriented in greater degree of crystallinity, its crystallites are oriented in the fibre axis direction, and its void structure is similar to that the fibre axis direction, and its void structure is similar to that of viscose fibres. Differences in the molecular and fine of viscose fibres. Differences in the molecular and fine structure of these fibres cause different sorption properties.structure of these fibres cause different sorption properties.
Lyocell fibres consist of longer molecules, they have a Lyocell fibres consist of longer molecules, they have a greater degree of crystallinity, its crystallites are oriented in greater degree of crystallinity, its crystallites are oriented in the fibre axis direction, and its void structure is similar to that the fibre axis direction, and its void structure is similar to that of viscose fibres. Differences in the molecular and fine of viscose fibres. Differences in the molecular and fine structure of these fibres cause different sorption properties.structure of these fibres cause different sorption properties.
Slide 39 of 40
INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
2.2 2.4 2.6 2.8 3.0 3.2 3.4
0.75
0.70
0.65
0.60
0.55
0.50
0.45
0.40
500
475450
425
400
375350
325
300275
250
Internal Surface of VoidsVoid volume
Void Diameter, nm
Void
Volu
me V
p, cm
/g
Speci
fic
Iner
Surf
ace
, Sp [
m2/g
MOD
LYO
VIS
Void Void DiameterDiameter
Void Void DiameterDiameter
Viscose:3.1Viscose:3.1
Lyocell: 3.0Lyocell: 3.0
Modal : 2.4Modal : 2.4
Viscose:3.1Viscose:3.1
Lyocell: 3.0Lyocell: 3.0
Modal : 2.4Modal : 2.4
Void Void VolumeVolume
Void Void VolumeVolume
Viscose:0.68Viscose:0.68
Lyocell: 0.62Lyocell: 0.62
Modal : 0.49Modal : 0.49
Viscose:0.68Viscose:0.68
Lyocell: 0.62Lyocell: 0.62
Modal : 0.49Modal : 0.49
Slide 40 of 40
INDIAN INSTITUTE OF TECHNOLOGYINDIAN INSTITUTE OF TECHNOLOGYContinued M. L. GULRAJANIM. L. GULRAJANI
Direct Dyes
References• The Diamond Jubilee of the Discovery of Direct Cotton Dyes, 1884 – 1944. By C.
M. WHITTAKER, JSDC, 1945, 201.• Direct Cotton Dyes, Common Salt, and Commonsense, By C. M. WHITTAKER, JSDC,
1942, 253. • Effect of the bio-salt trisodium citrate in the dyeing of cotton, H Gurumallesh Prabu
and M Sundrarajan, Color. Technol., 118 (2002) 131• Synthesis and Evaluation of Non-genotoxic Direct Dyes, Jin-Seok Bae* and Harold S.
Freeman, fibres and Polymers 2002, Vol.3, No.4, 140-146. • An investigation into direct dye aggregation, Martin Ferus-Comelo* and Andrew J
Greaves, Color. Technol., 118 (2002) 15. • Description of dyeing equilibria in the application of direct dyes, H Gerber, JSDC
VOLUME11 2 MAY/JUNE 1996 153. • The Application of Direct Dyes to Viscose Rayon Yarn and Staple, J. BOULTON,
J.S.D.C. 67 (1951) 522. • Structural Characteristics of New and Conventional Regenerated Cellulosic Fibers,Tatjana
Kreze and Sonja Malej, Textile Research Journal 2003; 73; 675. • Role of quaternary ammonium salts in improving the fastness properties of anionic dyes on
cellulose fibres Saima Sharif,a,b Saeed Ahmadb,* and Mian Muhammad Izhar-ul-Haqa, Color. Technol., 123, 8–17