Synthesis and properties of novel aziridinyl azo dyes from 2-aminothiophenes—Part 2: Application of some disperse dyes to polyester fibres

A series of yellow to greenish-blue aziridinyl azo dyes and their azo precursors containing a thienyl coupling moiety has been applied to conventional polyester fibre as well as microdenier polyester by high temperature exhaust dyeing. Heat transferability of these dyes onto polyester fibre has also been examined, using conventional heat-transfer printing techniques. The relevant dyeing characteristics, heat transferability, build-up, dyeability on microfibre polyester, washfastness and lightfastness are given. These aziridinyl dyes are reactive to polyester fibres under HT dyeing conditions. Fabrics dyed with aziridinyl dyes are more resistant to solvent extraction than those dyed with conventional dyes. Residual liquors showed only a pale colour when fabric dyed with aziridinyl dyes was dissolved and then precipitated, whereas a coloured polyester precipitate was obtained.     

Improving the Dye Coverage of Immature Cotton Fibres by Treatment with Chitosan

A study has been made of the sorption by cotton of chitosan (a partially deacetylated poly(N-acetyl-D-glucosamine)) which had been applied to fabric by pad and exhaust methods. Chitosan pretreatment increases the exhaustion of direct dyes and is also very effective in eliminating differences in colour between dyed immature and mature cotton fibres. Some reduction in dye fastness results from the chitosan pretreatment when the dyeings are aftertreated with a conventional cationic fixing agent. However, much higher levels of fastness are obtained by aftertreatment with fibre-reactive quaternary ammonium compounds; in general, these compounds produce dyeings of similar fastness properties on both untreated and chitosan-treated cotton.     

Dye-transfer Printing Systems Relying on the Use of Substrate Pre-treatment

The use of transfer printing techniques on synthetic polymer fibres is now well-established. Until recently, however, similar techniques on cellulose and mixtures containing appreciable percentages of cellulosic fibres were not commercially practical or acceptable because the colours were skittery and wash fastness was generally poor. The process described enables full, bright colours to be produced on fabrics composed of synthetic-cellulosic fibre blends (mainly polyester-cotton) and even on all-cotton; it requires a pre-treatment of the fabric with a resin formulation, which can usually be applied on conventional resin finishing equipment. Investigations have shown that some amino resins did accept dyes of the disperse type, and did produce acceptable prints, but it was generally found that the fastness properties of most were poor and the results comparable with that of acrylic, resin-treated fabrics. Further investigations led to the identification of the resin structure giving the best fastness properties, but, at the same time when using conventional papers, even with the right resin, these fastness properties varied from dye to dye.     

Graft copolymerization of acrylamide onto bamboo rayon and fibre dyeing with acid dyes

Bamboo is considered to be an important biopolymer with useful applications in various fields including textiles. It is a renewable natural resource of cellulosic nature and it originates from grass family. It gives maximum biomass per unit area and time. In general, cellulosic fibres do not have acid dyeability as those of polyamide fibres. Hence, it is difficult to dye such fibres, unless modified, with acid dyes which are relatively cheaper than the direct class of dyes. In the current study, the bamboo rayon fabric was grafted with acrylamide using potassium persulphate (KPS) as an initiator. The grafting conditions were optimized in terms of temperature, time, initiator and monomer concentrations. The grafted product was characterized using FTIR, TGA, SEM and analyzed for textile properties like moisture regain and yellowness index. The ungrafted and grafted fabrics were dyed using acid dyes and tested for colour strength and fastness properties. An increase in the dyeability of the order of 150?C230% was observed on grafting of bamboo rayon. The distinct improvement in moisture regain of the grafted fabrics was also observed, which is due to increase in the polarity of the fibres. Hence, better comfort can be expected out of such fabrics during summer. The bamboo rayon which is otherwise not dyeable with acid dyes, can be rendered acid dyeable by grafting technique.     

Surface treatment of cotton fabrics with chitosan

Antibacterial activities of cotton and polyester/cotton fabrics treated with chitosan or chitosan/DMDHEU have been investigated. The washing durability properties of the aforementioned fabrics were also studied. Another group of fabric samples produced from mature and immature cotton fibres were dyed with reactive dyes and the colour yields and colour differences of the dyed fabrics assessed. The surfaces of the treated and untreated cotton fabrics were observed by scanning electron microscopy to compare the morphology.     

Synthesis,spectral and dyeing properties of phenylazopyrazolone‐containing acylamide disperse dyes designed for poly(lactic acid)

A series of phenylazopyrazolone disperse dyes containing an acylamide moiety were synthesised from carboxyl‐containing acid dyes via chlorination and amidation with different sorts of amines. The structures of these new dyes were confirmed by Fourier Transform–infrared, proton nuclear magnetic resonance, mass spectroscopy and elemental analysis. Their solvatochromic properties in different solvents were also investigated and the absorbance spectra of the acylamide dyes in solution exhibited a red shift when dissolved in dimethylformamide, compared with acetone. Their dyeing behaviour, including dye sorption, colour build‐up and colour fastness properties on poly(lactic acid) fibres, was also determined, whereupon it was found that the tertiary acylamide dyes simultaneously exhibited high dye sorption and satisfactory colour build‐up and fastness properties on the poly(lactic acid) fabric.     

A New Insight into the Thermofix Dyeing of Polyester-Cellulose Blends

Novel experimental techniques have been used to show that in thermofix dyeing disperse dyes are transferred from cotton to polyester fibres—in a blend or union fabric—solely by a vapour-phase mechanism. Other possible modes of transfer were examined, but no evidence was found to support them. The heat fastness of paniculate disperse dyes on cotton was correlated with their transfer properties to polyester fibres. The various types of behaviour of disperse dyes in bulk application are explained. Functions of padding assistants and, in particular, a migration inhibitor and the importance of time and temperature in thermofixation procedures are dealt with in practical terms in Part II of the paper.     

Organoclays assisted vat and disperse dyeing of poly(ethylene terephthalate) nanocomposite fabrics via melt spinning

Polyethylene terephthalate nanocomposites containing six modified montmorillonite nanoclays were prepared by a melt compounding technique. The effect of intercalated compounds of montmorillonite on textile mechanical properties of resultant polyethylene terephthalate nanocomposite fabrics was investigated. Winding was not possible, when the polymers were first compounded with the desired amount of montmorillonite and then spun, as filament breakage occurred. Spinable polymer were only obtained by mixing polyethylene terephthalate master batches with 4 wt% montmorillonite, which contained tallow intercalating compound with pure untreated polyethylene terephthalate to a montmorillonite content of 0.5 wt%, thus decreasing the concentration of thermally degraded polymer chains. After spinning the fibres were drawn and knitted into fabric samples for further testing. The prepared polyethylene terephthalate nanocomposite fabrics using montmorillonite exhibited higher colour strength using vat and disperse dyes compared with those of the reference fabrics made from fibres spun without montmorillonite clay content and regular fabrics. The carbocyclic‐based vat dyes have higher colour strength values on polyethylene terephthalate nanocomposite fabrics if compared with heterocyclic‐based vat dyes. The colour fastness ratings for both vat and disperse dyeings secured very good to excellent washing and perspiration fastness on polyethylene terephthalate nanocomposite fabrics. All dyed fabrics showed excellent light fastness using vat and disperse dyes. The preparation of polyethylene terephthalate nanocomposite fabrics with improved textile mechanical and vat dyeing properties needs further investigations.     

Isoreactive Dyeing Systems

An isoreactive dyeing system is a system in which the sorption rate is kept constant throughout the whole kinetic period. A theoretical study of this condition was carried out using the modified kinetic equation of Cegarra–Puente and the Arrhenius equation. The isoreactivity equation is used to determine the conditions of temperature–time which should be applied during dyeing to achieve constant sorption at different sorption times. Finally, the theoretical values and those found experimentally in the dyeing systems: wool–acid dyes, viscose rayon–direct dyes and acrylic fibres–cationic dyes are compared.     

Fixation of reactive dyes using radio-frequency energy

Radio-frequency (r.f.) energy has been used to increase the fixation rate of reactive dyes on cotton fabric in pad-batch dyeing. A parallel-plate r.f. applicator was used to heat batches of fabric containing reactive dye formulations. The time required for fixation of the dyes was reduced from several hours to a few minutes by heating the fabric in the radio-frequency field. Reactive dyes incorporating three different types of reactive groups, vinylsulphone, nicotinic acid, and mixed vinylsulphone/ monochlorotriazine were studied and found to be applicable using the hot pad-batch method. The colour yield and wash fastness of dyeings with the vinylsulphone/monochlorotriazine bifunctional dyes using r.f.-assisted fixation was equal or superior to those of dyeings performed by conventional cold pad-batch dyeing methods.     

含2,4-二羟基二苯甲酮基团活性染料的合成与应用研究

本文以苯甲酸为原料,经酰氯化生成苯甲酰氯,再与间苯二酚反应生成中间体2,4-二羟基二苯甲酮,产率79.4%。然后以2,4-二羟基二苯甲酮为封闭基,对位酯为重氮组分合成了黄、橙、红和蓝色4只新结构的活性染料,并用质谱对其结构进行了表征。用合成的染料对棉纤维染色,测定了染料的上染率和固色率,黄色染料染色性能较差。与未染色的棉纤维相比,染色后棉纤维的紫外线透过率大大降低。未染色纤维UPF值为1.3,经过黄、橙、红和蓝色染料染色的棉纤维的UPF值分别为6.1、16.1、16.0、18.5,除黄色外都达到了很好的抗紫外线效果。     

Protection of lyocell fibres against fibrillation; influence of dyeing with bis-monochloro-s-triazinyl reactive dyes

Four bis-monochlorotriazinyl (bis-MCT) reactive dyes, including Procion Orange H-ER, together with Remazol Black B, were applied, in turn, to lyocell fibres and their wet abrasion resistance (Nass-Scheuer-Festigkeit) measured. The bis-MCT dyes performed poorly, showing that little cross-linking had occurred and all were inferior to Remazol Black B. The cross-linking propensity of Procion Orange H-ER was not superior to the other bis-MCT dyes evaluated. A possible explanation for the apparent superiority of Procion Orange H-ER in a recent paper published in this journal may lie with fabric construction but not with the suppression of fibrillation once it has occurred.     

The effects of dye structure and a cationic aftertreatment on the coverage of neps in cotton fabric

The effects of dye structure and aftertreatment with cationic fixative on the ability of a series of twelve direct dyes to cover neps in cotton fabrics have been examined. Colour differences before and after laundering have also been investigated.     

The role of natural dyes in the UV protection of fabrics made of vegetable fibres

The safest protection from ultraviolet (UV) radiation exposure is offered by textiles including various apparels, accessories such as hats and shade structures such as umbrellas. Their protectiveness depends on fabric composition, (natural, artificial or synthetic fibres), fabric construction (porosity, weight and thickness) and dyeing (natural or synthetic dyes, dye concentration, UV-absorbing properties, etc.). In this study the UV-protection properties were investigated on fabrics made of vegetable fibres (cotton, flax, hemp and ramie), with different construction parameters (drapery and apparel fabrics), dyed with some of the most common natural dyes. The effect of a tannins-based mordant (the galls of Quercus infectoria) on UV-protection capacity was also tested. UV radiation transmittance of fabrics was measured by two methods: one based on the utilisation of a spectrophotometer equipped with an integrating sphere (in vitro test), and the other based on outdoor measurements taken by a spectroradiometer. Transmittance measurements were used to calculate the Ultraviolet Protection Factor (UPF).Our results revealed that thick and dense (cover factor, CF > 94%) drapery fabrics made of vegetable fibres usually showed good UV-protection levels even if undyed. The use of the tannins-based mordant increased, even without dyeing, the UV-protection level up to the very good and/or excellent protection categories when fabric construction was suitable. Dyeing did not further increase the protection level.Lighter fabrics, usually used for apparel, even showed high UV-protection level after just dyeing, provided that CF was above 94%.Taking into account the high concentrations of dyes used in the present work and the utilisation of mordants containing tannins, slight differences in UV-protection capacity were detected among natural dyes tested and between the two different methods of transmittance measurement. However, UV-protection category defined from outdoor measurements was often higher than that calculated by the in vitro test, indicating an underestimation of the actual protection level of tested fabrics assessed by the latter.     

The role of natural dyes in the UV protection of fabrics made of vegetable fibres

The safest protection from ultraviolet (UV) radiation exposure is offered by textiles including various apparels, accessories such as hats and shade structures such as umbrellas. Their protectiveness depends on fabric composition, (natural, artificial or synthetic fibres), fabric construction (porosity, weight and thickness) and dyeing (natural or synthetic dyes, dye concentration, UV-absorbing properties, etc.). In this study the UV-protection properties were investigated on fabrics made of vegetable fibres (cotton, flax, hemp and ramie), with different construction parameters (drapery and apparel fabrics), dyed with some of the most common natural dyes. The effect of a tannins-based mordant (the galls of Quercus infectoria) on UV-protection capacity was also tested. UV radiation transmittance of fabrics was measured by two methods: one based on the utilisation of a spectrophotometer equipped with an integrating sphere (in vitro test), and the other based on outdoor measurements taken by a spectroradiometer. Transmittance measurements were used to calculate the Ultraviolet Protection Factor (UPF).Our results revealed that thick and dense (cover factor, CF > 94%) drapery fabrics made of vegetable fibres usually showed good UV-protection levels even if undyed. The use of the tannins-based mordant increased, even without dyeing, the UV-protection level up to the very good and/or excellent protection categories when fabric construction was suitable. Dyeing did not further increase the protection level.Lighter fabrics, usually used for apparel, even showed high UV-protection level after just dyeing, provided that CF was above 94%.Taking into account the high concentrations of dyes used in the present work and the utilisation of mordants containing tannins, slight differences in UV-protection capacity were detected among natural dyes tested and between the two different methods of transmittance measurement. However, UV-protection category defined from outdoor measurements was often higher than that calculated by the in vitro test, indicating an underestimation of the actual protection level of tested fabrics assessed by the latter.     

Dye distribution in the dyeing of mixed denier polyester fabrics

Microfibre polyester is sometimes blended with higher denier fibres to achieve good aesthetic effects at lower cost. Two polyester yarns of 1.4 and 0.7 denier were dyed singly and together with a range of depths of CI Disperse Blue 79, and the dye distribution over the course of the dyeings was examined. The uptake is initially greater on the microfibre, but as dyeing is continued the distribution becomes more even, and eventually the same concentration of dye is present on both fibres. Based on the common observation that a given concentration of dye produces a lighter shade on a microfibre, the redistribution of dye during the process causes a continuing shade change even though the bath exhaustion is constant. A mixture of three dyes produced a stable hue on a fabric of 1.0 denier polyester after 20 min at a fixed dyeing temperature, but when dyed on a fabric of 1.0 and 0.5 denier yarns, a change in hue continued for more than 60 min.     

疏水性葸醌染料在聚乳酸织物上的染色性能

The dyeability of polylactide fabric has been investigated with the substituted aminoanthraquinone hydrophobic dyes.Their application to the polylactide fabric led to good exhaustion values and good wash fastness between 4 and 5.Microscopic assessment of cross-sections of the dyed polylactide fibres confirmed that these dyes could penetrate into the fibres.The nature of the substituted amino groups showed little influence on the wash fastness,but clearly influenced the exhaustion and light fastness.     

Dispersant‐free dyeing of poly(lactic acid) fabric with temporarily solubilised disperse dyes from azopyridone derivatives

Poly(lactic acid) fibre is derived from annually renewable crops and known to be 100% compostable. In order to extend its environmental friendliness into the dyeing process, dispersant‐free dyeing of poly(lactic acid) fabric with three temporarily solubilised azo disperse dyes based on hydroxypyridone moiety containing a β‐sulphatoethylsulphonyl group was investigated. The dyes were successfully applied to poly(lactic acid) fabric without the use of dispersants. The colour yields of the dyes on poly(lactic acid) fabric were observed to be dependent on dyebath pH and dyeing temperature. The optimum results were obtained at pH 4–5 and 110 °C. One of the dyes showed a colour yield as good as that of a commercial disperse dye and good build‐up on poly(lactic acid) fabric. All of the dyes could be alkali cleared owing to ionisation of the dye under mild alkaline conditions. Wash fastness was good to very good, and light fastness was good. The chemical oxygen demand levels of the poly(lactic acid) dyeing effluent from the dyes were considerably lower than those from a commercial disperse dye.     

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%.     

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.