International Journal of Advances in Science Engineering and Technology, ISSN: , LIKELY MECHANISM OF DYE ADHESION ON FABRICS

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1 LIKELY MECHANISM OF DYE ADHESION ON FABRICS 1 D. MALOMO, 2 S.A ABIMBADE, 3 A.K OLUWASEUN, 4 O.EGHAREBA 1,2,3 Department of Industrial Chemistry, Federal University Oye Ekiti, Nigeria 4 Rubber Research Institute of Nigeria, Benin City, Nigeria 1 dosu.malomo@fuoye.edu.ng Abstract - The mechanism of adhesion of dyes as colouring agents on different types of fabrics is hereby examined. The dyes under study include, basic dyes, acidic dyes, azo dyes, mordant dyes, and vat dyes while the fabrics are cellulosic materials, wool fabrics, nylon 6,6 fabrics, nylon 6 fabrics, silk fabrics and polyester materials. The principle of adhesion proposed leading to the fastness of the colourants is illustrated by the bonding of atoms and molecules arising from intermolecular interactions between functional groups of the dyes and the substrate materials. The functional groups involved are hydroxyl group (-OH), carboxylic group (-COOH), carbonyl group (=C=O), imino group (-NH-) ester group (- COOR), amide group (-CONH2) as well as conjugation in aromatic groups. The types of bonding proposed are ionic, covalent, dative covalent, dipole-dipole forces, and inter molecular hydrogen bonding. The study also shows that adhesion may be enhanced by physical entrapment of the colouring molecules on the substrate. Keywords - adhesion, entrapment, bonding, functional group, fabric and dye I. INTRODUCTION A dye is a colouring substance that has affinity for the substrate to which it is being applied (Popoola, 2015) It is usually applied in an aqueous solution and may require a mordant to improve the fastness on the fabric which are essential fiber material. A fibre being a single elongated piece of a given material roughly round in cross-section often twisted with other fibres to form a thread. Dyes posses colour because they absorbs light in the visible region of the electromagnetic spectrum ( nm). They have at least one chromophore, colour-bearing group usually with conjugated double bond system. They exhibit resonance of electrons which is stabilizing force in organic compounds (Abrahat, 2009). Most dyes also contain auxochromes (colour enhancers) and examples includes; Carboxylic acids, sulfonic acid, amino and hydroxylic groups.while these are not responsible for colour, auxochromes are e-donating groups which shift absorption spectrum towards longer wavelength in dye molecule having conjugated π-bond system (Popoola, 2015). Example of these groups include, -CH3, -OH, -OCH3, -NH2,-NHCH3 and N(CH3)2. They most often influence dye solubility. Fabric refers to any material made through weaving, knitting, spreading, crocheting or bonding that may be used in production of further goods such as; garments. Fabrics are manufactured from various raw materials which are of natural or synthetic origin or a mixture of the two. Essentially fabrics contain fibres material made of continuous filaments which are discrete and elongate like the length of thread pieces. Fabrics are classified on the basis of origin, processes or its end uses. (Balter, 2009) The applications of dye on fabrics for the purposes imparting colours to enhance aesthetic value have been a process as old as civilization. The chemistry behind the mechanism of adhesion of dye on fabric is complex, as a member of factors must be considered. This paper set out to examine various types of dyes and fabrics as well as present likely mechanistic processes by which some selected dyes are adhered on the surfaces of some chosen fabrics. The study will therefore, discuss the nature and chemistry of dye/fabrics, chemical structures/functional groups present in dye and fabrics as well as various bonding types. This information will form the basis of postulating possible mechanism by which dye as a colouring material is adsorbed on some fabrics surfaces. II. CLASSIFICATION OF DYES Dyes can be classified as organic or inorganic natural or of synthetic origin. They are also classified by method of application or by the nature of chromophores they posses. Natural dyes are obtained from natural source such as plants, animal or mineral. Roots, nuts and flowers, and leaves contain natural dyes. A common example is indigo Synthetic dyes which are man-made colouring substance of organic origin made from coal tar and benzene derivatives.. They cost less and have ability to offer wide range of colours. They are applied applied in medicine, chemistry, plastics, paint, ink, rubber and cosmetics.dye application for numerous surfaces or processes of application form basis for another method of classification. Examples include leather dyes for leather, oxidation dyes for hair, optical brightness for paper, solvent dyes for coloured lacquers, while others are fluorescent dyes for sports; fuel dyes fuels, smoke dyes for military activities, sublimation dyes for textile printing. Ink jet dyes are used for inkjet printers and leuco dyes for electronic industries and papers. Classification of dyes based on the chemical composition of a dye is possible and this is associated with the chromophore present in the dye. A 1

2 chromophore is a functional group present in the molecule of a dye which imparts the molecule with the ability to absorb uv radiation strongly thereby leading to colour generation. Some examples are listed include the following: Table 1: Examples of chromophores and some applications bonds. This makes the reactive dye a permanent dyestuff, most ideal for dyeing cotton and some other cellulose fibres.the azoic dyeing technique involves the application of insoluble azo dye on fibre by direct contact using a coupling component.the toxic nature of the chemicals used is now responsible for decline in applicatio. The dispense dyes are water- insoluble finely ground materials which in the process of dispersing agent are applied as spray or powdering form on polyester, nylon and acrylic fibres. The dyeing rate can be significantly influenced by choice of dispersing agent used during the grinding process. The sulphur dyes are used to produce dark colours,,they are cheap and it involves reaction between an organic compound such as nitrophenol and sulphide source. III. SYNTHETIC DYES A typical example of a dye structure classified by using chromophore is the Yellow azo dye where the double bond in the Azo group N=N- is in conjugation with the double bonds in the two aromatic groups. This increases the intensity of colour generation.majority of dyes stuff is primarily consumed by the textile industries and this necessitates industrial classification of the substance particularly the azo types. The dyes used in the textile finishing industries are acidic, basic, direct, mordant, vat, reactive and dispense types. Others are sulphur dyes and the azo types. The acidic dyes are applied on silk,wool and nylon. They are anionic have ability to attach to the cationic group of the fibre through salt formation ( Aspland, 1997).Basic dyes are water soluble cationic dyes which contain some other dye which helps the uptake of dye on the fibre ( Longstaff, 1983).Direct and substantive dyes are used on cotton, paper, wool, silk and nylon. They are ph indicators as well. (Gregom, 1986).The mordant dyes are chemical substance which improves the fastness of the dye against water light and perspiration.the mordant dye helps to form a strong link between the fabrics and the dye, example include metal hydroxide, tannic acid, aluminum, iron and chromium. The colour of the final product depends on the dye and the mordant used, for example a piece of cloth immersed in turkey red (alizarin) is red with aluminum mordant but violet with iron mordant. Most mordant produced from heavy metals are hazardous to health and care must be taken in their applications. Vat dyes are insoluble in water and cannot be applied directly but reduction in alkaline medium produce water soluble alkaline metal salt of the dye which has affinity for textile fibre.the reactive dye as they are called have the ability to react with the fibre substrate through formation of covalent A Synthetic dye is any of the organic dyes originally derived from coal-tar derivatives, but currently synthesized from benzene and its derivatives. The first human-made organic dye, mauveine, was discovered by William Henry Perkin in Thousands of synthetic dyes have since been prepared. Synthetic dyes quickly replaced the traditional natural dyes. They cost less, they offer a vast range of new colours, and they imparted better properties upon the dyed materials.they are used in medicine, chemistry, plastics, paint, printing ink, rubber and cosmetics IV. STRUCTURES OF DYES i. ACID BLACK DYE ii. iii. BASIC RED DYE VAT DYE 2

3 V. FUNCTIONAL GROUPS IN DYES iv. REACTIVE DYE v. AZOIC DYE vi. DIRECT RED DYE VI. CLASSIFICATION OF FABRICS Generally fabrics are classified on the basis of the origin of fibres (natural or synthetic) or its processing or its end use ( Balter, 2009). Classification on the basis of origin gives natural or synthetic fabrics. The natural fabrics are those created from the fibres of animal coats, the cocoons of silkworms and plant seeds, leaves and stems. They do not change colours on exposure to uv light until they lose tensile strength ( Lorenzani,1998). The synthetic fabrics on the other hand are man-made from inorganic or organic materials. They can be made to specification depending on end use condition ( Garret, 1963) vii. NITRO DYE (MARITUS YELLOW) viii. MORDANT RED ix. x. SULPHUR RED VII. FABRICS OF NATURAL ORIGIN The fabrics obtained from natural fibres include cotton, silk, linen, wool, leather, ramie, hemp and jute. The cotton fabric is one of the most unique of them all as it has distinctive features which makes it adjust easily with climatic conditions. It keeps body cool in summer by absorbing sweat easily and gives warmth feel in winter season. Silk is equally weather friendly and it is the strongest natural fabric which also has the quality of softness, luster, beauty and luxurious appearance. The linen, another naturally sourced fabric is considered king of natural fabric because of its versatility in application such as homes furnishing and apparel production. Linen does not cause irritation and allergy yet, it is strong and durable. It is easily maintained by mere hand washing. The wool fabric is a weather friendly natural fabric which is soft strong and durable with excellent aesthetic value. It does not wrinkle easily and is resistance to dirt, wear and tears. The wool fabrics does not get inflame easily as it only smoulders in flame (Morgan 2005). A comfortable fabric in hot and cold weather, resistant to 3

4 temperature aberration is the leather fabric. It absorbs water vapour and retains dimensional stability under stress (Kite, 2005).Other types of fibres in common use include; ramie,hemp and jute. VIII. FABRICS OF SYNTHETIC ORIGIN IX. STRUCTURE OF FABRICS The chemical structures of various fabrics are given below for the identification of different types of functional groups that will enhance the understanding of dye-fabric association These are fabrics produced by chemical processes by man through the use of petroleum as raw material. These include acetate, chiffon, acrylic, organza, lastex,nylon,velvet,polyester,taffeta,denim,rayon,geor gette,viscose,grey and polypropylene. Acetate fabrics are made from cellulose of cotton or wood pulp. It is resistant to shrinkage, moth and dew. The fibre has soft and luxurious appearance (Kadolph,2007). The Chiffon fabrics are manufactured using silk, rayon, polyester or cotton. They are specially used for making bridal gowns, evening dresses, pron dresses and scarves. This material commands magical look on the wearer thereby exuding high personality. The acrylic fabrics are synthetic materials used for making shirts and ladies clothes and seats for chairs. It maintains its quality for a long time because of its excellent wear and tear resistances (Koham, 1995).Organza fabric refers to a thin, plain weave fabric made from silk yarn worms, and filament fibres of nylon and polyester. They are nice to touch with high degree of sophistication and uniqueness. A special type of fabric made from latex is known as lastex fabrics. They are elastic in nature and are used with other complex fibres (Dedie, 2005). Nylon fabric is synthetic materials used for clothing, shirts covers and industrial appliances. They are made from the polyester of the amides obtained from petroleum (Munro,1990). Velvet fabrics are used for making trousers, shirt, bed sheets, covers and curtains. Polyester fabrics is another man-made material which has the unique qualities of wrinkle resistance and springing back to original shape. They are strong and soft materials and can be mixed with other materials such as the cotton. Taffeta fabrics are crisp, soft and smooth materials manufactured from rayon, silk or nylon. They are used for women garments. Denim is a rugged cotton material which is generally coloured with indigo dye to create blue jeans. The rayon fabric is a synthetic textile fabric which is produced by forcing a cellulose solution through fibre spinnerets. Georgette fabric is a sheer and strong silk or silk like clothing that often comes with a dull creped surface. It is exquisite and unique fabric which enjoys high demand in the market. Viscose fabric material is commonly used for coating, stocking and under wears as well as staple for towels and table cloth.grey fabric is used for cloth manufacturing due to its cost effectiveness and longevity. The material show cases aesthetics and glamour. The polypropylene is a synthetic material suitable for winter season because of its ability to keep the body warm. Cellulose Fabric Nylon 6,6 Fabric Wool Fabric Silk Fabric Polyester Fabric Nylon 6 Fabric Functional Groups in Fabrics Cellulose Fabric -OH Wool Fabric -COOH, -NH2, -CONH-, -C=O, -NH- Polyester Fabric -CH2-, -C=O, -COOR, Aromatic Nylon 6,6 and Nylon 6 -CONH, Silk Fabric -COOH, CONH-, -NH2, -C=O, - NH- 4

5 X. THE PHYSICO-CHEMICAL PRINCIPLES OF THE MECHANISM OF DYE ADHESION ON FABRICS The interaction between acid dye and cellulose fibres is almost nonexistent, but a partial attraction is proposed as follows (NOUN, 2011) Adhesion is the ability of two different materials to stick together by material interactions and formation of chemical bonds. The process of dyeing depends not only on the type of the dye but on the type of fibre. Generally reactions between dyes and fabrics must take into account the various types of forces exerted by one material upon another. All dyeing mechanism can be divided into three broad categories (Popoola, 2015) Formation of specific bond between the dye and fabric owing to the covalent bond, hydrogen bond, ionic bond dipole-dipole interaction and london forces. The formation of these bonds is dependent on the type of functional groups present in the dye and the fabrics 2. Non-specific attraction between dye and fabric owing to ion exchange or van waals forces. 3. In the absence of any interactions dyes can be adherent on fabric by physical entrapment. The chemistry of interactions between some pairs of dye-fabric materials are also based on hydrophilic/hydrophobic properties as well as the formation of salt linkages between dye and fabric functional group Acid dye-cellulose fabric. The oxygen of the OH group in the cellulose molecule interacts with the electropositive or cationic Na atom of the sulphonic acid group of the dye. This bond, though weak but several of it promote the adhesion of the dye on the cellulose material. Another example is observed in the interaction between the electronegative oxygen atom of the cellulose and the cationic Na atom of the dye molecule. Acid dyes are generally applied to fibres such as silk, wool, nylon and modified acrylic fibres. Acid dye-wool interaction may simply be represented by the formation of intermolecular hydrogen bonding between the H-atom of dye and the electronegative N atom of the fibre. 2. Basic Dye- Wool Fabric System (a) (b) 5

6 3. Reactive dye Wool Fabric System The cellulose fabric is represented by the ROH in the mechanism. The adhesion between the dye here and the cellulosic molecule could be due to the H bonding observed between the H atom of the dye and the electronegative oxygen atom of the cellulose molecule. 8. Direct Red Dye - Cellulose System 4. Azo Dye Wool Fabric System In No 8 above the cellulose fabric is represented by the ROH in the mechanism. A dipole dipole attraction between the Na atom and the Oxygen atom where non -bonding electrons are found can enhance adhesion. Several of such attractions between the two molecules proposed for the affinity of the two surfaces for each other. 5. Acid Black Dye Cellulose 9. Reactive Dye Cellulose Fabric Sytem 6. Azo Dye Cellulose System Cellulose fabric dye fabric system for adhesion 7. Mordant Red Dye Cellulose Fabric System dye adhesion with cross linking The fibre reactive dye adhesion is due to the formation of ether linkages (R-O-R) to the OH groups of the cellulose (R-OH). The cellulose is activated by treatment with Na2CO3 base to form alkoxide (RO) 6

7 groups which then attack the trianzene rings nucleophilically and substitute for the chlorine leaving groups (equation 2). The two chlorine atoms can be replaced leading to the cross linking dyefibre, thereby enhancing durability of the fibre (Popoola, 2015) 10. Mordant Red Dye Nylon 6 Fabric System these polar groups or in many cases the formation of intermolecular hydrogen bonding, In addition to polar forces, the normal non-polar Vander Waals forces operate in dye molecule having aromatic nuclei where the several π electrons participate in the non-polar attraction. The polyesters are easily susceptible to this type of attraction. (Popoola, 2015). A combination of these forces and physical enhancement due to compatibility promote adhesion thereby improving fastness to light, washing, bleaching, rubbing and perspiration. This in the long-run leads to maintenance of fabric quality and aesthetics. REFERENCE Hydrogen bonding between the oxygen atom of the dye and the H atom of the fabric is likely to enhance adhesion between the two surfaces. CONCLUSION From the examples of dye adhesion on fabrics discussed in this paper, it is evident that textile materials posses polar groups in large quantities which aid bonding. Some dyes adhere by chemical reaction arising from the presence of anxochromes. This is the case with reactive dyes where covalent bonds are formed. The attraction of the dye for fibre may therefore arise from the dipolar interaction of [1] Abarhart E.N (1977). Dyes and their Intermediate, New York Chemical Publisher.,PP 1-12 [2] Aspland J.P (1997). Textile Dyeing and Colouration Association of Textile Chemist and Colourist.pp2-310 [3] Balter M. (2009). Cloth Make the (Hu) Man Science 325 [4] Dedic, Bette Jo, Potter Mike (1995). Fabric insect and Pest.Clothes Moth and Carpet Beetles. [5] Garret, Alfred (1963).The Flash of Genius Princeton. New Jersey. PP [6] Gorgery P (1986). Azo Dye: Structure of Dye and Pigment. PP [7] Kadolph, Sara J. (2007). Textile, 10thed Pearson. Pg 230 [8] Kite, Marion, Ray Thomson (2005).Conservation of Leather and Related Materials Butterworth Hemenann.Pg 204 [9] Kohan, Melvin, (1995). Nylon Plastic Handbook.Hanser / Gardner Publication [10] Longsaff E. (1983). An Assessment and Categorisation on Selected dyestuff. Dye and Fabric pg [11] Lorenzani, Shirleys (1998). Natural Fibers and their Composites [12] Morgan P. (2005). Carbon Fiber and their composite [13] Munro J.M (1990). Cotton, Harlow Longman Scientific and Technical. New York, John Wiley. [14] NOUN, (2011). National Open University of Nigeria) Study Material on Colour Chemistry and Technology, pg 57. [15] Popoola V.A. (2015). The Chemistry of Colours in Dyes and Pigments, Wits Publishing Ltd, 7