ABSTRACT

 

The synthesis of some disperse dyes base on anthraquinone was achieved by coupling diazotised 1-aminoanthraquinone and tetrazotised 1,4-diaminoanthraquinone respectively with pyridone derivatives. The identity of the resultant dyes were investigated using UV-visiblespectrophotometry, Fourier Transform – Infra Red and the relative molecular mass of the intermediates were confirmed using mass spectrometry. The applications of these dyes to polylactide fabrics were also studied. The results obtained indicated that the monoazo dyes exhausted better than the disazo dyes on polylactide fabrics. The fastness properties to washing, perspiration, sublimation and light were observed to be good to very good for all the dyed polylactide fabrics.

 

TABLE OF CONTENTS

 

Title page…………………………………………………………………………………………………………….ii Dedication………………………………………………………………………………………………………….iii Declaration …………………………………………………………………………………………………………iv Certification …………………………………………………………………………………………………………v Acknowledgements ……………………………………………………………………………………………..vi Abstract ……………………………………………………………………………………………………………..ix Table of contents ………………………………………………………………………………………………….x List of figures ……………………………………………………………………………………………………xvi List of tables ………………………………………………………………………………………………………xv Abbreviations……………………………………………………………….…………. xx 1.0 INTRODUCTION…………………………………………………………………………………………1 1.1 Dyes………………………………………………………………………………………………………………1 1.2 Pigment………………………………………………………………………………………………………….3 1.3 Fibres…………………………………………………………………………………………………………….4 1.4 Polylactide Fibre……………………………………………………………………………………………..5 1.5 Azo Disperse Dyes………………………………………………………………………………………….7 1.6 Justification……………………………………………………………………………………………………8 1.7 Aim and objectives of this Resear…………………………………………………………………….8 1.8 Scope of this Work………………………………………………………………………………………….8 2.0 LITERATURE REVIEW …………………………………………………………………………….10 2.1 Developments of Natural Dyes……………………………………………………………………..10 2.1.1 Natural dyes……………………………………………………………………………………………….10 2.1.2 Alizarin………………………………………………………………………………………………………11
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2.1.3 Indigo ………………………………………………………………………………………………………..12 2.1.4 Kermes………………………………………………………………………………………………………12 2.1.5 Log wood …………………………………………………………………………………………………..13 2.1.6 Tyrian purple……………………………………………………………………………………………..13 2.2 Development of Synthetic Dyes…………………………………………………………………….13 2.2.1 Basic dyes ………………………………………………………………………………………………….17 2.2.2 Vat dyes …………………………………………………………………………………………………….18 2.2.3 Anthraquinone vat dyes ……………………………………………………………………………….19 2.2.4 Solubilised vat dyes …………………………………………………………………………………….19 2.2.5 Sulphur dyes ………………………………………………………………………………………………20 2.2.6 Direct dyes …………………………………………………………………………………………………20 2.2.7 Phthalocyanine dye ……………………………………………………………………………………..21 2.2.8 Azoic dyes ………………………………………………………………………………………………….21 2.2.9 Acid dyes …………………………………………………………………………………………………..22 2.2.10 Acid mordant and metal complex dyes ………………………………………………………..23 2.2.11 Disperse dyes ……………………………………………………………………………………………23 2.2.12 Reactive dyes ……………………………………………………………………………………………25 2.3 Colour and Chemical Constitution ……………………………………………………………….26 2.4 Poly(Lactic) Acids ………………………………………………………………………………………..29 2.4.1 Properties of polylactide fibres ……………………………………………………………………..30 2.4.2 Dyeing PLA fibre with disperse dyes …………………………………………………………….31 2.5 Heterocyclic Disperse Dyes …………………………………………………………………………..32
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2.6 Fibre Structure In Relation To Dying …………………………………………………………..32 3.0 MATERIALS AND METHODS …………………………………………………………………..33 3.1 Materials ……………………………………………………………………………………………………..33 3.2 Apparatus and equipment……………………………………………………………………………33 3.3 Methods……………………………………………………………………………………………………..33 3.4Synthesisof the Intermediates ……………………………………………………………………..34 3.4.1 Synthesis of 1-amino-2-hydroxy-4-methyl-5-cyano-6-pyridone ………………………. 35 3.4.2 Synthesis of 1-methyl-2-hydroxy-4-methyl-5-cyano-6-pyridone ………………………35 3.4.3 Synthesis of 1-ethyl-2-hydroxy-4-methyl-5-cyano-6-pyridone ………………………… 35 3.4.4 Synthesis of 1-butyl-2-hydroxy-4-methyl-5-cyano-6-pyridone ………………………… 35 3.4.5 Synthesis of 1-dedocyl-2-hydroxy-4-methyl-5-cyano-6-pyridone ………………. 35 3.5 Diazotization and Coupling ………………………………………………………………………… 36 3.5.1Diazotisation and Coupling Procedure for Synthesis of Dyes 7a, 7b, 7c, 7d and 7e …………………………………………………………………………………………………………..36 3.5.2 Synthesis of dyes 7f and 7g …………………………………………………………………………36 3.5.3 Tetrazotisation and coupling procedure for the synthesis of dyes 10a, 10b, 10c, 10d, and 10e …………………………………………………………………………………………37 3.5.4 Synthesis of dyes 10f and 10g ………………………………………………………………………37
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3.6Purification of Dye ………………………………………………………………………………………37 3.7Percentage Yield of Dyes ……………………………………………………………………………..37 3.8Determination of Melting Point of the Dyes ………………………………………………….38 3.9 Infra-Red Spectra of the Dyes ………………………………………………………………………38 3.10Visible Absorption Measurements ………………………………………………………………38 3.11Application of the Dyes on Polylactide Fabric ……………………………………………..39 3.11.1 Dyeing of the polylactide non-woven fabric …………………………………………………39
3.11.2 Effect of temperature on dyeing …………………………………………………………………. 40 3.11.3 Effect of time on dyeing …………………………………………………………………………….41 3.11.4 Effect of pH on dyeing ………………………………………………………………………………41 3.12Fastness Properties …………………………………………………………………………………….41 3.12.1 Wash fastness test ……………………………………………………………………………………..41 3.12.2 Fastness to perspiration ……………………………………………………………………………..42 3.12.3 Light fastness test (Nunn, 1979) …………………………………………………………………44 3.12.4 Sublimation fastness test ……………………………………………………………………………44 3.12.5 Fastness to hot pressing ……………………………………………………………………………..45 4.0 RESULTS ……………………………………………………………………………………………………47
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5.0 Discussion……………………………………………………………………………………………………60 5.1 Summary of the Synthetic Routes of Dye Intermediate and Dyes ……….…….60 5.2 Synthesis of Coupling Components ……………………………………………………………….61 5.3 Syntheses of the Dyes …………………………………………………………………………………..62 5.4Assessment of Mass Spectral ………………………………………………………………………..63 5.5FT-IR Analysis of the Synthesised Dyes ……………………………..…………..64 5.6Visible Absorption of the Synthesized Dyes …………………………………………………..65 5.6.1 Solvatochromic effects ………………………………………………………………………………..67 5.6.2 Effect of acid on visible absorption band (Halochromism) ……………………………….69 5.6.3 The molar extinction coefficient (ɛ) ………………………………………………………………70 5.7Effect of Temperature on Dye Exhaustion ……………………………………………………71 5.8Effect of Time on Dye Exhaustion ………………………………………………………………..72 5.9Effect of pH on Dye Exhaustion ……………………………………………………………………73 5.10Assessment of Washing Fastness ………………………………………………………………..74
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5.11Assessment of Fastness to Perspiration ……………………………………………………….74 5.12Assessment of Fastness to Light ………………………………………………………………….75 5.13Assessment of Fastness to Sublimation ……………………………………………………….76 5.14Assessment of Fastness to Hot Pressing ………………………………………………………76 6.0 CONCLUSIONS AND RECOMMENDATIONS………………………………………….77 6.1 Conclusions…………………………………………………………………………………………………77 6.2 Recommendation …………………………………………………………………………………………77 REFERENCES …………………………………………………………………………………………………79 APPENDIX A ………………………………………………………………………………………………….86 APPENDIX B …………………………………………………………………………………………………..91 APPENDIX C ………………………………………………………………………………………………..105 APPENDIX C ………………………………………………………………………………………………..108
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CHAPTER ONE

INTRODUCTION
1.1 Dyes
A dye may be defined as a colorant that has substantivity for a substrate, either inherent or induced by reactants or more correctly, as a coloured substance capable of application in aqueous or non-aqueous solution or in an aqueous dispersion to a substrate so that the substrate acquires a coloured appearance. The substrate is usually textile fibre but may also be paper, leather, hair, fur, plastic material, food stuff or drug and so forth (Ogunmakin, 1992). Dyes are coloured because they absorb light of a wavelength within the visible spectrum. This characteristic is promoted by the existence in the molecule of an organic compound of one or more certain unsaturated groups of atoms called “chromophores”. The most important of them are: C=C – Ethylenic group C=O – Keto group -N=O – Nitroso group -N=N- – Azo group NO2 – Nitro group When these chromophores are introduced into organic compounds that absorb light only in the ultraviolet region, these groups bring about absorption at lower frequencies and the new compound are coloured. For example, anthracene is colourless.
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anthracene
But anthraquinone is a pale yellow compound, because it contains two keto groups C=O
O
O
Anthraquinone
In addition, certain substituents such as hydroxyl, amino and substituted amino groups
greatly enhance the colour yielding properties of a chromophore but do not themselves
result to absorption in the visible spectrum. These substituents are called auxochrome
(Carr, 1995) and some are listed below:
NH2 – Amino
NH2R – Alkyl amino (R = alkyl)
Cl, Br – Halogen groups
NHR2 – Di alkyl amino (R2)
OH – Hydroxyl group
SO3H – Sulphonic acid group
COOH – Carboxylic group
Unlike most organic compounds, dyes possess colour because they:
(1) absorb light in the visible spectrum (400–700 nm),
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(2) have at least one chromophore (colour-bearing group), (3) have a conjugated system, i.e. a structure with alternating double and single bonds, (4) exhibit resonance of electrons, which is a stabilizing force in organic compounds (Abrahart, 1977). When any one of these features is lacking from the molecular structure the colour is lost.
1.2 Pigment
This can be defined as a substance in a particulate form that is substantially insoluble in a medium, but which can be mechanically dispersed in this medium to modify its colour or light scattering properties or may be defined more correctly, as a natural or synthetic inorganic or organic substance that impacts a colour including black or white to other materials. Pigments may be in powder form or easily powdered substance mixed with a liquid in which it is relatively insoluble and used in making paints, enamels, and other coating material, inks, and rubber and also for imparting opacity and other desirable properties as well as colour. The main distinction between dye and a pigment is that, if the colorant has affinity for the substrate and will become a part of the coloured material without the need for an intermediate binder, it is considered a dye. This substantivity or affinity for the substrates clearly distinguishes dyes from pigments (Christie, 2001). Pigment on the other hand must be incorporated into a binder to be attached to the substrate as in paint film attached to the wall of a house. Dyes can be applied to textile fibre in two major ways, which are dyeing and printing:
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Dyeing is a uniform application of colorant to textile substrates. Textile materials often show natural affinity for appropriate dyes and readily absorb them from aqueous solutions or dispersions giving the right pH, concentration and temperature with also the help of auxiliaries to control the rate of dyeing. Textile printing involves the production of a predetermined coloured pattern on a fabric, usually with a definite repeat. It can be described as a localised form of dyeing, applying colorant to selected areas of the fabric to build up the design. Textile printing, like textile dyeing, is a process for applying colour to a substrate. However, instead of colouring the whole substrate (cloth, carpet or yarn) as in dyeing, print colour is applied only to defined areas to obtain the desired pattern. This involves different techniques and different machinery with respect to dyeing, but the physical and chemical processes that take place between the dye and the fibre are analogous to dyeing (Mazharul, 2011).
1.3 Fibre
Hearle (1963) quotes definition of a fibre according to the Textile Institute (1960) thus; a fibre is “a unit of matter characterized by fineness, flexibility, and high ratio of length to thickness” (Carr, 1995). There are many fibrous structures in nature, but only those which can be spun into yarns suitable for weaving or knitting are classified as textile fibres. For any fibre to have a commercial value, it must possess certain fundamental properties (Trotman, 1970). It must be readily obtained in adequate quantity at a price which will not make the end- product too costly. Such fibre must have sufficient strength, elasticity and spinning power. In addition to these fundamental properties there are others which are desirable, such as durability, softness, absence of undesirable colour, and affinity for dye.
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In this work a new fibre known as Polylactide fibre is of great interest, its nature and dye ability with disperse dye is examined.
1.4 Polylactide Fibre
Recently substrates based on Polylactide (PLA) fibres have received attention worldwide because of their attractive advantages and their availability from a naturally renewable carbohydrate resource. In principle, PLA decomposes to carbon dioxide and water over time, without causing pollution to the environment. PLA can be conveniently produced from corn, sugar or sweet vegetables and is not a petroleum based material. At present, the proportion of corn crops used for PLA synthesis is less than 0.02% (Liang et al, 2010). This implies that the production of PLA cannot lead to potential food crisis. PLA is an aliphatic polymer that is subject to high ultraviolet (UV) penetration into fabric composed of its fibres. Also dye performance is normally different on PLA as obtained in Polyethylene Terephthalate (PET). For instance, many commercial disperse dyes have exhaustion levels less than 50% on PLA but have exhaustion levels over 90% on PET (Liang et al., 2010). Light fastness levels are also different on PLA and PET. Therefore, in addition to developing alternative dyeing methods for PLA, the synthesis of dyes that take the structural nature of PLA into consideration is essential to improving dye exhaustion and light fastness.
Petroleum-derived textile fibres accounted for 53.52% of the global textile fibre market in 2005.The production of these non-degradable and non-renewable synthetic polymers will definitely be affected by the crisis of oil depletion which is estimated to reach its peak
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production before 2025 (Mohammed et al., 2011). The pollution resulting from millions of tons of packages incinerated every year, contributes to the global warming by greenhouse effect. These circumstances induced the need for new resources of degradable and renewable fibres which are more sustainable and environmentally friendly. A potential solution towards the environmental impact has been through the use of biodegradable polymers such as poly(lactic acid) [(C3H4O2)n] . These new biodegradable plastics have been used in various applications such as biomedical care products, packaging materials, and textile fibres. Sorona from DuPont, Polyhydroxyalkanoates (PHAs) and IngeoTM from Nature Works LLC are some examples of biodegradable polymers which have been successfully commercialized. IngeoTM are poly(lactic acid) fibres, which are the first biodegradable polymer made from 100% annually renewable natural resources, such as corn. PLA fibre such as Ingeo is very interesting fibre. It combines the performance of both natural and synthetic materials. Their properties like low inflammability, excellent UV stability, high resilience, excellent wicking, and moisture management are remarkable. However, the attractive biodegradability that gives PLA fibres their importance seems to be the weak point that prevents them from becoming more popular. Although PLA has great potential as substitute for Polyester (PET) fibre in cotton/polyester blends. They present different extents of degradation in an alkaline medium after cotton fabric preparation (Mohammed et al., 2011).
Poly(lactic acid) as an aliphatic polyester, can be derived from 100% renewable resources such as corn. PLA, whose raw material (such as corn) is both renewable and non-polluting, eliminates the use of a finite supply of oil as a raw material. Poly(lactic acid) is the first
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melt-processable natural-based synthetic fibre, it is biodegradable, compostable and recyclable (Ozan, 2011) . Ease of melt processing, its unique property spectrum, renewable source origin, and ease of composting and recycling at the end of its useful life have led to a growing interest in PLA fibres and acceptance over a range of commercial textile sectors. PLA can be dyed with disperse dyes, just like PET fibres, under high temperature and pressure, although a modified dyeing method is employed since PLA has a low affinity to conventional water-soluble dyes. Conventional processes and finishing technologies can be used for processing PLA fabrics. The processing temperatures conventionally used for PET need to be reduced since the melting point of PLA is lower than that of PET. The PLA disperse dyeing conditions recommended by DyStar11 are 15–30 minutes at 110–115oC at a pH of 4.5–5.0. As the dye bath is cooled down, disperse dye molecules are deposited on the surface of the fibres as relatively large particles due to their limited water solubility. These surface deposits of „unfixed‟ dye can lead to a reduction in fastness properties as well as a dulling of the shade. Generally, a reductive clearing step is carried out after dyeing with disperse dye (Joonseok, 2011).
1.5 Azo Disperse Dyes
Disperse dyes are sparingly water soluble dyes. The most important class of disperse is the azo class. This class of azo disperse dyes may be further subdivided into four groups, the most numerous of which is the amino azo benzene class. This class can be altered to produce bathochromic shifts. A range of heterocyclic aminoazobenzene dyes are available. These give bright dyes, and are bathochromically shifted to give blues. The third class of disperse dye is based on heterocyclic coupling components, which produce bright yellow
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dyes under which this research work falls. The fourth class is disazo dyes. These tend to be quite simple in structure. Other than these, there are disperse dyes of the carbonyl class and a few from nitro and polymethine classes (Yusuf, 2012).
1.6 Justification
Dyes used on PLA fibres usually give low exhaustion and/or poor light fastness. It is hoped that synthesizing a low molecular weight dyes derived from pyridone as coupling component will provide good substantivity and better light fastness dyes for PLA.
1.7 Aim and Objectives of this Research
The aim of this research work is to synthesize some new azo dyes derived from anthraquinone as diazo component and pyridone as coupling component. The specific objectives of this research work are:
i. To examine the effect of increasing alkyl chain length on pyridone
ii. To characterize the synthesized dyes.
iii. To apply the synthesized dyes on a non-woven Polylactide fabrics.
iv. To investigate the effect of variables such as temperature, time and pH on dye exhaustion on Polylactide fibre.
v. To investigate the performance properties such as wash, light and perspiration fastness.
1.8 Scope of this Work
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This work is mainly to synthesize monoazo and disazo anthraquinone disperse dyes derived from pyridone as coupling component. To compare the exhaustion of mono azo and disazo synthesized dyes. To compare the fastness properties of these dyes on the Polylactide materials for example,, washing, light and perspiration.

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