Chemical Modification of Cotton to Enhance its Dyeability Abdur Rehman Submitted in accordance with the requirements for the degree of Doctor of Philosophy The University of Leeds Department of Colour and Polymer Chemistry February 2007 The candidate confirms that the work submitted is his own and that appropriate credit has been given where reference has been made to the work of others. This copy has been supplied on the understanding that it is copyright material and that no quotation from the thesis may be published without proper acknowledgement. I Acknowledgements Acknowledgements The author would like to express his sincere gratitude to the following: ■ Professor D M Lewis and Dr. M Clark for their excellent supervision, constant guidance and enthusiastic encouragement throughout the course of this research. It was a great experience to learn from their vast experience and knowledge. ■ Special thanks to Mr. Algy Kazlauciunas for his sincere help in the analysis of dye distribution inside the fibre. All the members of the technical staff for help and advice, especially Mr. Henry Willingby, Mr. M Asaf and Jeff. Pitchford for their technical support. ■ All my fellow PhD. students for their friendship and moral support throughout My PhD. ■ And at last but not the least to my mother for her continuous encouragement, prayers and moral support throughout the period of my PhD and living abroad for studies for such a long time. To my brothers and sisters of the family for their encouragement, advice and moral support. Abstract II Abstract The dyeing of cotton can be problematic to the dyeing industry when dyeing with different dye classes because a significant amount of dyes find their way into effluents. Cotton dyed with different class of dyes suffers from washing-off, wash-fastness, light-fastness, rub- fastness and ring-dyeing problems. A method to increase the substantivity for the cotton fiber is to create a positive charge on the fiber. For this purpose the cotton fiber was pre­ treated with cationising agents Servon XRK and NMM derivative. Servon XRK and NMM derivative were used as part of EU Frame Work V. Servon XRK (3-chloro-2-hydroxy-N, N, N-trimethyl-l-propanaminium chloride) and NMM derivative [4-(3-chloro-2- hydroxypropyl)-4-methylmorpholin-4-ium chloride)] were applied to cotton by pad-batch method. In this research vat dyes, acid dyes, azoic colourants and reactive dyes have been used. The dyeings from vat dyes gave improved colour yield values when applied to the Servon XRK and NMM modified cotton fabrics as compared to the unmodified cotton fabrics. The dyeings from anthraquinone vat dyes (Cl Vat Violet 1, Cl Vat Red 13 and Cl Vat Green 1) on modified (Servon XRK and NMM) cotton fabric absolutely did not lose any colour in wash-off liquor as the dyeings from anthraquinone vat dyes (Cl Vat Violet 1, Cl Vat Red 13 and Cl Vat Green 1) on the unmodified cotton fabric gave a significant amount of colour in wash-off liquor. Vat dyes on the modified cotton fabric gave overall better dyeing results than on the unmodified cotton fabric. III Abstract Disulphonated acid dyes Cl Acid Red 13 and Cl Acid Red 17 gave better wash-fastness results than monosulphonated (Cl Acid Red 88) and trisulphonated (Cl Acid Red 18 and Cl Acid Red 27). The light-fastness results were better for the dyeings from trisulphonated acid dyes than the monosulphonated and disulphonated acid dyes. The dyeings from Cl Acid Blue 193 gave good dyeing results than the dyeings from Cl Acid Violet 92. The overall dyeing results are better for the dyeings obtained by the application of Naphthol AS to the Servon XRK modified cotton fabric by pad-dry and pad-batch-dry methods followed by coupling than the corresponding dyeings on the unmodified cotton fabric. Sumifix Supra Blue BRF and Sumifix Supra Red 3BF applied on the Servon XRK modified cotton fabric gave improved dyeing results than applying on unmodified cotton fabric. Reactive dyes co-applied with NMM have given overall better results than when applied without NMM. Table of Contents IV Table of Contents Chapter 1 Introduction _____________________________________________________ 1 1.1 Cellulose and cotton________________________________________________________1 1.1.1 Introduction_________________________________________________________ 1 1.1.2 Source of cellulose____________________________________________________1 1.1.3 History of cotton _______________________________________________2 1.1.4 Morphology of cotton__________________________________________ ______3 1.1.5 Molecular structure of cellulose__________________________________ _____ 4 1.1.6 Degree of polymerisation of cellulose___________________________________7 1.1.7 Supramolecular structure of cellulose_________________________________ _ 8 1.1.8 Degradation of cellulose ___________________________________________ _ 11 1.1.9 Cellulose substitution________________________________________________ 13 1.1.10 Physical properties of cellulose______________________________________15 1.2 Cotton in textiles _________________________________________________________ 16 1.2.1 Trends in cotton production___________________________________________16 1.2.2 Cotton preparation__________________________________________________ 17 1.3 Colour perception ________________________________________________________18 1.3.1 Textile dyeing_______________________________________________________19 1.3.2 Cellulose during dyeing______________________________________________20 1.4 Dyes for cotton___________________________________________________________ 20 1.4.1 Direct dyes_________________________________________________________ 21 1.4.2 Reactive dyes_______________________________________________________23 Table of Contents V 1.4.3 Vat dyes___________________________________________________________ 30 1.4.3.1 Reducing agents__________________________________________________ 32 1.4.3.2 Leuco dyeing______________________________________________________34 1.4.3.3 Prepigmentation method____________________________________________34 1.4.3.4 Semipigmentation method _________________________________________ 35 1.4.3.5 Solubilised vat dye powders________________________________________ 35 1.4.3.6 Fastness properties of vat dyes______________________________________35 1.4.4 Azoic colourants_____________________________________________________36 1.4.4.1 Cl Coupling components ___________________________________________37 1.4.4.2 Cl Diazo components______________________________________________37 1.4.4.3 The advantages of azoic dyeing_____________________________________38 1.4.4.4 The disadvantages of azoic dyeing___________________________________39 1.4.4.5 Stripping_________________________________________________________ 39 1.4.4.6 Fastness properties________________________________________________ 40 1.4.5 Sulphur Dyes_______________________________________________________40 1.4.5.1 Cl Sulphur dyes____________________________________________________41 1.4.5.2 Cl Solubilised Sulphur dyes________________________________________ 42 1.5 Cellulose Modification __________________________________________________ 43 1.5.1 Problems associated with dyeing cotton using reactive dyes _____________43 1.5.2 Advantages and disadvantages of cotton modification___________________45 1.5.2.1 Advantages_______________________________________________________45 1.5.2.2 Disadvantages_____________________________________________________45 1.5.3 Modification of cotton with low molecular weight amino compounds_____45 Table of Contents VI 1.5.3.1 Animation of cotton through p-toluenesulphonyl chloride______________ 45 1.5.3.2 Animation of cotton through 2 - chloroethyl amine____________________47 1.5.3.3 Animation of cotton with sodium 2 — aminoethyl sulphate 47 1.5.3.4 Animation of cotton through P-chloroethyldiethylamine_______________ 48 1.5.3.5 Animation of cotton through esterification____________________________48 1.5.3.6 Animation of cotton through nicotinoyl thioglycollate__________________50 1.5.3.7 Animation of cotton through N-methylol type compounds_____________ 51 1.5.4 Modification of cotton through quaternary amino compounds____________52 1.5.5 Modification of cotton with amino polymers __________________________ 58 1.5.5.1 Modification of cotton with sandene 8425___________________ ________ 58 1.5.5.2 Modification of cotton with chitosan _______________________________ 59 1.5.5.3 Modification of cotton with Hercosett 125____________________________ 60 1.5.5.4 Modification of cotton with Polyepichlorohydrin-amine polymers________62 1.5.5.5 Modification of cotton with Polymer PL (ICI)________________________ 62 1.5.6 Modification of cotton to produce reactive fibres_______________________ 63 1.5.7 Modification of cotton with cross-linking agents ___________________ _ _ 65 1.6 Acid dyes_________________________________________________________ 69 1.6.1 Non-metallised acid dyes____________________________________________ 70 1.6.2 Pre-metallised acid dyes 72 1.7 Aims and objectives______________________________________________________ 74 1.8 References________________________________________________ 75 Chapter 2 Experimental Techniques 84 Table of Contents VII 2.1 Introduction_____________________________________________________________ 84 2.2 Measurement of colour___________________________________________________84 2.2.1 Colour strength_____________________________________________________84 2.2.2 Measurement of dye fixation using fk values___________________________85 2.3 UV/Vis Spectroscopy______________________________________________________86 2.3.1 Elementary Theory__________________________________________________ 86 2.3.2 Absorption Intensity_________________________________________________ 88 2.3.3 The UV/Visible Instrument 89 2.3.4 Determination of dye concentration using Ultra-Violet and Visible spectroscopy________________________________________________________ 90 2.4 Colour fastness___________________________________________________________ 91 2.4.1 Wash-fastness_______________________________________________________92 2.4.2 Light-fastness_______________________________________________________93 2.5 Light Microscopy_________________________________________________________94 2.6 References________________________________________________________________95 Chapter 3 Application of Vat Dyes to Unmodified and Modified Cotton____________96 3.1 Introduction______________________________________________________________96 3.2 Experimental_____________________________________________________________97 3.2.1 Materials___________________________________________________________ 97 3.2.1.1 Fabric 97 3.2.1.2 Other reagents 97 Table of Contents VIII 3.2.1.3 Dyes_____________________________________________________________ 97 3.2.2 Application of Servon XRK (3-chloro-2-hydroxy-N, N, N-trimethyl- 1 -propanaminium chloride) to cotton___________________________________99 3.2.2.1 Preparation of the padding solution___________________________________99 3.2.2.2 Padding conditions______ _________________________________________ 100 3.2.2.3 Cold wash-off_________________________________________ ___________100 3.2.2.4 Drying_______________________________________________________ ____101 3.2.3 Application of NMM derivative [4-(3-chloro-2-hydroxypropyl) -4-methylmorpholin-4-iumchloride)] to cotton__________________ _____ 101 3.2.4 Dyeing of vat dyes__________________________________________ _______102 3.2.4.1 Dyeing profile___________________________________________________ 102 3.2.4.2 Reduction of vat dyes______________________________________________102 3.2.4.3 Oxidation of vat dyes__________________________________________103 3.2.4.4 Washing-off________ _____________________________________________103 3.3 Results and discussion____________________________________________________104 3.3.1 Washing-off_______________________________________________________104 3.3.2 Colour yield_______________________________________________________110 3.3.3 Wash-fastness test_________________________________________________ 111 3.3.4 Light-fastness______________________________________________________119 3.3.5 Rub-fastness_______________________________________________________120 3.3.6 Microscopic images of yam/fibre cross-sections_______________________ 123 3.4 Conclusions 127 Table of Contents IX 3.5 References_______________________________________________________________128 Chapter 4 Application of Acid Dyes to Cotton Modified With Servon XRK_________ 129 4.1 Introduction_____________________________________________________________129 4.2 Non-metallised acid dyes_________________________________________________ 130 4.2.1 Experimental______________________________________________________130 4.2.1.1 Materials_________________________________________________________ 130 4.2.1.2 Dyeing profile____________________________________________________132 4.2.1.3 Washing-off__________________________________________________ 133 4.2.2 Results and discussion__________________________________________ ___ 133 4.2.2.1 Exhaustion values for the dyeings from non-metallised acid dyes_________________________________________________________ 133 4.2.2.2 Colour yield values for the dyeings with pale and heavy shades______________________________________________________135 4.2.2.3 Wash-fastness for the dyeings from given set of dyes__________________136 4.2.2.4 Light-fastness_____________________________________________________143 4.2.2.5 Multi-wash tests for the dyeings from non-metallised acid dyes_________146 4.2.2.6 Microscopic images of yarn/fibre cross-sections______________________ 150 4.3 Pre-metallised acid dyes_________________________________________________ 152 4.3.1 Experimental______________________________________________________152 4.3.1.1 Materials_________________________________________________________ 152 4.3.1.2 Dyeing profiles____________________________________________________154 4.3.1.3 Washing-off______________________________________________________155