Improved fixation of dyes on polyamide fibres. Part 3: Using 2-chloro-4,6-di(aminobenzene-4′-vinylsulphone)-s-triazine [XLC-VS] as an after-treatment of nucleophilic aminoalkyl dyes

A mono-aminoalkyl-s-triazine polysulphonated dye was used as a model nucleophilic dye. When applied to nylon 6,6 this dye gave good uptake under midly acidic conditions but, as expected, no covalent bonding was observed. When such dyeings were after-treated with anionic dispersions of the specially synthesised, fibre substantive, cross-linking agent, 2-chloro-4,6-di(aminobenzene-4′-vinylsulphone)-s-triazine [XLC-VS], a very significant degree of covalent bonding was achieved.     

Level fast dyeing of wool with nucleophilic amino-alkyl dyes and crosslinking agents-Part 2: using bifunctional crosslinking agents

Covalently binding dyes through reactions between commercially available bi-functional crosslinking agents, wool and aminoethylaminotriazinyl dyes is discussed. In particular, dye fixation, levelness and fastness properties have been assessed and shown to be very promising. The proposed system offers the dyer the opportunity to achieve covalent bonding of the dye to the fibre in a controlled manner, thus ensuring good levelness.     

Use of a novel water-soluble arylating agent to dye wool and wool blends with disperse dyes

A series of water-soluble fibre-reactive arylating agents were synthesised and evaluated from the stand-point of improving fibre coloration with disperse dyes. In particular, the compound, sodio-2,4-dianilino-6-[4'- β -sulphatoethylsulphonylanilino]- s -triazine (FAA 200) was found to be promising; this compound could be applied in the same bath as a disperse dye at pH 5–6. Under the latter conditions this compound showed high substantivity to wool and at the boil readily underwent β -elimination of the sulphate ester residue to give the vinyl sulphone reactive group which adds on to nucleophilic sites in the fibre to form a covalent bond. Coapplication with commercially available disperse dyes gave bright, level dyeings that exhibited promising wet fastness. FAA 200 was used as an auxiliary to dye disperse dyes on both fibre components of a wool–polyester blend fabric; it was found that addition of hydrogen peroxide or sodium thiocyanate was necessary to obviate reduction of certain disperse dyes when dyeing at 120 °C.     

Co-application of hydroxyalkyl dyes and polyphosphonic acids to cotton to achieve dye—fibre covalent bonding

The dyeing of cotton to a high standard of wet-fastness with hydroxyalkyl dyes and a polyphosphonatecrosslinker system has been investigated. Dyes containing hydroxyalkyl groups were prepared, by the reaction of commercial reactive dyes with ethanolamine, and applied to cotton fabric in the presence of polyphosphonic acid crosslinking agents using cyanamide as a catalyst. The application was carried out using a pad-thermosol method. The effects of cyanamide concentration, the nature of the crosslinker and the type of hydroxyalkyl dye were studied in detail. It was concluded that multifunctional polyphosphonates are capable of producing dyeings on cellulosic fibres exhibiting a high degree of covalent bonding (fixation). The efficiency of dye fixation at ca. 2% pure dye (owf), obtained from this method, was greater than 90%.     

Instrumental Colour Prediction A Potential Aid to Dye and Process Selection

A relationship has been established between the dyeing properties of fibre–reactive dyes and the spectral reflectance properties of the colours produced on machine–washable wool. The information gained in routine dye calibration for instrumental colour–prediction systems may be used by the practical dyer for dye selection. The spectral reflectance properties of the resultant dyeings are explained in terms of the diffusion, fixation and level–dyeing properties of specific fibre–reactive dyes applied to wool by exhaust and pad–dyeing processes.     

Dyeing of polyester and its blends with some disazo dyes derived from the disodium salt of chromotropic acid and their chelates with transition metal ions

Disazo dyes derived from the disodium salt of chromotropic acid and their chelates with metal ions were applied on polyester, polyester/cotton and polyester/wool blend fibres as disperse dyes. The fastness to washing, perspiration, rubbing and light of the resultant dyeings were measured. The bonding of dye or its complexes to the fibre and the effect of substituent groups on the colour fastness of the dyes are discussed.     

The production of level fast dyeings on wool with nucleophilic dyes and a crosslinking agent

A specially prepared alkylamino dye and a crosslinking agent precursor, hexamethylene tetramine (HMTA), have been applied together to wool fabric to achieve level fast dyeings. This new method is compared with the conventional reactive dyeing method and the optimum application conditions of the new method are discussed.     

New Approaches to Washfast Dyes for Wool:

Dyes incorporating β-isothioureidopropionamide and β-isnthioureidoethyl salt groups have been synthesized by reaction of the corresponding bromide or iodide with thiourea. Such dyes can be applied in the cationic form to wool and bask-dyeable fibres, and then, by raising the pH to 9–10, decomposed on the fibre to give fast dyeings. These dyes can also be successfully applied as disperse dyes to appropriate fibres by carrying out the decomposition before dyeing in the presence of dispersing agents. By a combination of these two systems, both components of wool polyester blends can be dyed with the same dye. The high washfastness of isothiouronium dyes on wool is thought to be due to insolubilization within the fibre rather than to mixed disulphide formation with cystine.     

Possibilities of polymer‐aided dyeing of cotton fabric with reactive dyes at neutral pH

Water‐soluble polymers have versatile application, viz., water‐soluble polyacrylates have been widely used in the reactive dyeing of cellulosic fibers and the related soaping as an important component of the leveling and washing agent. In this article, one such water‐soluble polymer, polyacrylic acid has been synthesized, characterized, and applied in conjunction with various types of reactive dyes, namely triazinyl, vinyl sulfone, high exhaustion, and bifunctional reactive dyes, along with crosslinking agents, namely glycerol 1,3‐dichlorohydrin and hexamethylene tetramine‐hydroquinone, respectively. One of the crosslinking agents (the former one) has been synthesized in the laboratory. Crosslinking agent is necessary to adhere the dye molecule onto the cellulose macromolecule. Different process sequences have been formulated and explored for dyeing purpose. All such dyeings were carried out at neutral pH. The dyed samples were assessed through color strength in terms of K/S values and their fastness properties were assessed by standard methods. All such dyeings were compared with conventional dyed samples. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and Application of Some New Reactive Chlorohydrin Dyes

Azo and phthalocyanine dyes carrying the chlorohydrin group, as the precursor of the reactive epoxy group, were prepared using new catalyzed reactions. The reactive group is attached to the coupling component in some cases and to the diazonium component in other cases. A phthalocyanine dye carrying two reactive groups was also synthesized. The dyeing of cotton, wool and multifibre fabrics was studied, under different dyeing conditions. Various techniques of dyeing and printing were used. Exhaustion and padding methods were investigated for dyeing, and direct, reserve and discharge methods for printing. One–stage and two–stage procedures were employed for both printing and dyeing. It was found that the chlorohydrin reactive dyes prepared in the present work could be applied by nearly all known methods of dyeing and printing on cotton, wool, viscose rayon, nylon and acrylic fibres. The dyeings obtained had satisfactory fastness properties and showed fairly good dye fixation on the substrate.     

Exhaustion of Dyes on Wool at 105C

Laboratory trials have shown that many wool dyes are almost completely exhausted from the dye liquor after only 5 min at 105C, while the strength loss of the wool is no greater than in conventional dyeing methods. The uniformity of reactive dyeings under these conditions is reported.     

Functionalisation of lyocell. Part 1: Amination of lyocell with m-phenylenediaminesulphonic acid derivatives

A series of four colourless, water-soluble agents, based on m -phenylenediaminesulphonic acid, and designed to aminate lyocell, have been synthesised. Each agent carried one or two aromatic amino groups ortho to a water solubilising sulphonic acid group, together with one or two electrophilic groups. The electrophilic groups studied were dichlorotriazinyl, monochlorotriazinyl, vinylsulphonyl and triazinyl betaine. The agents were applied to lyocell by padding techniques, and neutral-exhaustion dyeing of the aminated fibres, with low, medium and high reactivity reactive dyes, in the presence of salt, were performed. Only the high reactivity dichlorotriazinyl dye gave encouraging results. The aminated fabrics, containing aromatic amino groups with an o -sulphonic acid, were insufficiently nucleophilic to allow significant covalent bonding with the low/medium reactivity dyes at both 60 and 80 °C.     

Pad-Batch Dyeing of Wool with Reactive Dyes

A process for the production of fast, bright dyeings on wool cloth is described. Reactive dyes applied by a pad-batch (cold) method yield level dyeings with very high colour yields. Virtually 100% fixation has been obtained with Procion M (ICI) dyes applied to wool from mildly acidic solutions, after batching for up to 24 h at room temperature. Yellowing of wool does not occur under these conditions, which facilitate the production of dyeings of a brightness and fastness that cannot be achieved under conventional dyeing conditions for wool.     

Synthesis of a di‐(p‐sulphophenoxy)‐s‐triazine reactive dye and its application in wool fabric ink‐jet printing

Reactive dyes based on p‐sulphophenoxy‐s‐triazines were synthesised, characterised and applied to wool fabric by ink‐jet printing. The extent of dye‐fibre covalent bonding (% fixation) was measured on prints produced using different development methods. The most promising method to obtain high dye‐fibre fixation values was to interleave the printed wool with a pre‐wetted cotton fabric and store for 3 h. Steam fixation was also investigated but gave lower fixation values. The degree of dye hydrolysis vs time in the ink formulation was evaluated because ink stability is critical in commercial operation; a reformulated ink based on a phosphate buffer was found to improve ink stability.     

Synthesis and dyeing properties of polyvinylamine dyes for cotton

Novel polyvinylamine dyes were designed and synthesised from poly(N‐vinylformamide‐co‐vinylamine) and reactive dyes, then used to dye cotton fibres by the dip‐pad‐steam process, with the dyeing methods being examined in detail. Each polyvinylamine dye was fixed to cotton without a crosslinking agent through covalent bonds formed between the reactive group of the dye and the cotton fibres. A fixation of 99% was achieved, with grades of 4 and 4‐5 wash and dry‐rub fastness, respectively.     

The Reactions of Disulphide Dyes for the Covalent Coloration of Keratin

The synthesis of one ortho- and three para-azo disulphide dyes is described. Disulphide exchange between these dyes and model compounds (cysteine and thioglycollic acid) has been studied. Previously reported work has indicated that covalent binding of colouring matters to wool can occur by disulphide exchange. The present dyes were therefore applied to keratin. The lack of fastness of the ortho-azo dye showed that no disulphide exchange leading to covalent bonding occurred. The para-azo disulphide dyes underwent disulphide exchange, but under the conditions used, this was effective only at high concentrations ofdye. Even then, only slight covalent bonding was achieved.     

Chemical modification of cotton to improve fibre dyeability

A new fibre-reactive quaternary compound containing an acrylamide residue was synthesised and used as a cotton modification reagent. The agent was applied to cotton fabrics using a pad-bake process. It was found that the treated fibre could be dyed with reactive dyes without the addition of salt or alkali. The reactive dyes were almost completely exhausted and showed a high degree of covalent bonding with the pretreated cellulose. The effect of varying the pretreatment conditions was investigated and the optimum conditions for pretreating and dyeing were established.     

Neutral dyeing of wool and wool/polyester blend fabrics using sulphatoethylsulphone reactive‐disperse dyes

Two models of temporarily anionic sulphatoethylsulphone reactive disperse dyes were applied to wool, polyester and wool/polyester blend fabrics at different dyeing pH. Maximum exhaustion values and colour yield were observed at pH 7. The results showed that reactive disperse dyes containing bis‐sulphatoethylsulphone reactive groups were more convenient for neutral dyeing of wool and wool/polyester blend fabrics if compared with a dye containing a mono‐sulphatoethylsulphone group. Excellent to very good wet fastness properties on all dyed fabrics were achieved.     

Application of sodium benzoyl thiosulphate from aqueous solution to wool and its effect on substantivity of disperse dyes. Part 1: synthesis and characterisation of sodium benzoyl thiosulphate

The introduction of bulky aryl residues into wool fibres not only enhances their disperse dyeability but also improves their settability, shrink resistance and imparts easy‐care properties. It would be highly desirable for colourists to achieve such effects when dyeing or printing wool from an aqueous solution as wool/polyester blend fabrics could be dyed and printed with the same dye; furthermore, in the case of an all‐wool fabric pretreated with such arylating systems, following dyeing or printing with disperse dyes, dye fixation can be achieved by dry heat procedures. A water‐soluble, fibre‐reactive arylating agent, sodium benzoyl thiosulphate, was therefore synthesised, characterised and its stability to hydrolysis in aqueous media was examined.     

Quaternary reactive dyes containing a thioether‐ethylsulphone group. Part 2; Application methods for the dyeing of nylon†

A member of the new series of cationic reactive dyes containing a thioether‐ethylsulphone grouping referred to in Part 1 of this series has been applied to nylon at pH 3–10. The dye is water soluble and shows excellent substantivity for nylon 6.6 when dyed at the boil at pH 8–10. Under alkaline conditions, gradual β‐elimination back to the vinylsulphone dye occurs and covalent bond formation quickly takes place with the fibre; the higher the pH the more rapidly this occurs. Dyeings carried out at pH 10 showed very good brightness and levelling, together with good wash fastness. The light fastness of dyeings at moderate depth was 4–5 on the Blue Wool scale.