Direct coloration of textiles with photochromic dyes. Part 1: Application of spiroindolinonaphthoxazines as disperse dyes to polyester,nylon and acrylic fabrics†

1,3,3‐Trimethylspiroindoline‐2,3′‐3H‐naphth[2,1‐b][1,4]oxazine ( 1a ) and 6′‐piperidino‐1,3,3‐trimethylspiroindoline‐2,3′‐3H‐naphth[2,1‐b][1,4]oxazine ( 1b ) were applied as disperse dyes to polyester, nylon and acrylic fabrics. Under optimised dyeing conditions, photochromic fabrics were produced which, on irradiation with ultraviolet or exposure to sunlight, turned blue ( 1a) or blueish‐purple ( 1b ). Dye 1a showed enhanced photochromic colour change performance compared with dye 1b . The photochromic colour build was highest on nylon and lowest on acrylic fabric. The colour change properties and the technical performance (wash fastness and photostability) of the photochromic fabrics were evaluated using specifically adapted colour measurement methods. The data were analysed in terms of variation of lightness, a*, b*, chroma, hue angle and ΔE, colour difference before and after exposure, and K/S curves as a function of irradiation time. The fabrics generally showed good wash fastness. Although the colour build‐up decreased with exposure to the Xenotest fadeometer, some residual photochromism remained after prolonged exposure.     

Substituent effects on the colour,dyeing and fastness properties of 4-phenylazo-1-naphthylamines and of 2-acetylamino-5-methoxy-4-N-ß-cyanoethyl-N-ß-hydroxyethylaminoazobenzene

The synthesis of a series of blue disperse dyes obtained by diazotisation of substituted anilines and coupling with 2-acetylamino-5-methoxy-4-N-ß-cyanoethyl-N-ß-hydroxyethylaniline and to N-ß-hydroxyethyl-1-naphthylamine is described. Substituent effects on the colour of the dyes is discussed, with particular respect to analogous dyes derived from 4-N-ß-cyanoethyl-N-ß-hydroxythylaniline. Some dyes from trisubstituted anilines as diazo component colour polyester in deep blue shades of generally good fastness properties.     

Textile applications of photochromic dyes. Part 4: application of commercial photochromic dyes as disperse dyes to polyester by exhaust dyeing

A series of commercial photochromic dyes was applied to polyester fabric as disperse dyes. The photocoloration properties of the dyed fabrics were investigated by applying techniques previously established in our laboratories using an independent source of ultraviolet irradiation and traditional colour measurement instrumentation. The dyed fabrics showed reversible photochromism, developing pronounced colours from weak background colours on irradiation with ultraviolet light and returning to their original state when the ultraviolet light source was removed. However, the extent of photocoloration and the depth of background colour varied significantly with the particular dye used. The dyeing procedure was optimised by maximising the degree of photocoloration, expressed as the colour difference (ΔE₁) between the colour developed after ultraviolet exposure and background colour, while minimising the background colour, expressed as the colour difference (ΔE₂) between unexposed dyed and undyed fabrics. Optimum dyeing concentrations were determined. The colour development and fading properties, fatigue resistance and storage stability of the dyed fabrics were investigated.     

Structure—wet fastness relationships of some blue disperse dyes for polyester

A range of monoazo blue disperse dyes has been synthesised by coupling benzenoid and heterocyclic diazo components to aniline derivatives containing ester functions. The colour properties and wet fastness of the dyes on polyester at 1/1 standard depth have been examined and rationalised in terms of dye structure. Styryl dyes have also been prepared in order to compare their wet fastness properties to those of the azo dyes.     

An investigation of an instrument‐based method for assessing colour fastness to light of photochromic textiles

A new method for evaluating the light fastness of photochromic fabrics was established, aimed at replacing the conventional method with an instrumental method. This method was based on comparing the colour difference of photochromic fabrics after light exposure with measured values of the colour differences of the blue wool references after fixed periods of light exposure. This method benefits from replacing the traditional visual evaluation of colour difference between exposed and unexposed areas of textile samples with a more accurate, instrument‐based measurement of the colour difference. The light fastness is then evaluated by comparing the colour difference with tabulated values of colour differences brought about by light exposure, for increased periods of time, of standard blue wool references. This method could be used for measuring light fastness of both traditional and photochromic fabrics. However, blue wool references and tested samples should be exposed to light under similar conditions when using this method to measure colour fastness to light of fabrics.     

The light fading mechanism of dyes derived from rhubarb extract

The effect of relative humidity and mordanting on the fading kinetics and colour change of dyes derived from rhubarb extract on wool and silk has been investigated. Wool samples showed negligible change in colour even after 100 h of exposure, whereas silk samples became significantly darker. Relative humidity in the range of 10–45% and mordanting did not appear to affect the rate of fading on both the fibres. However, the rate and extent of change in colour (ΔE) on exposure was different for different mordants. The high resistance of the dye to light fading indicates that the dye is present in a highly aggregated form in silk and wool.     

Dyeing properties of CI Acid Blue 193 and the non‐equivalent properties of CI Acid Black 194 produced by different manufacturers

This paper presents the results of research conducted into the colour properties of commercial metal complex dyes CI Acid Blue 193 and CI Acid Black 194. Three chromium(III) complexes with different colours were identified using thin‐layer chromatographic analysis and then separated by preparative chromatography. It was found that colour differences of the examined dyes depend on the ratio of the three components in CI Acid Blue 193 and CI Acid Black 194, and that these differences are typical for each of the commercial products. The colour differences of the components were expressed as ΔS, calculated as the difference in the areas under the absorption curve of the individual components in the range 400–700 nm after spectrum normalisation. The UV‐vis spectroscopic and CIELAB colorimetric properties (at 1% owf on polyamide) of eleven samples of CI Acid Black 194 were investigated. From these results, the proportions of the three components were derived. Theoretically, dyes sold under the same CI name are interchangeable. In practice, the obtained colour of the dyed material is different owing to the difference in composition namely the ratio of the components in the tested dyes. Consequently, the result of polyamide dyeing with the studied dyes CI Acid Blue 193 and CI Acid Black 194 is a redder or greener hue. It has been concluded from these findings that the production of identical dyeings may be impossible when dyes from different sources are employed.     

Cement paste colouring in concretes

Tests have been carried out with chemicals that give rise to coloured compounds through a selective reaction with certain mineral species present in cement paste. In the case of carbonated concretes (pH≅9), the reaction with potassium ferrocyanate dyes the cement paste a strong blue colour that disappears when the concrete is treated again with a slightly more alkaline solution. Both in carbonated concretes and in young concretes with an alkaline reserve (pH≅12.5), the tannic acid dyes the cement paste dark brown.     

Synthesis of temporarily solubilised azo disperse dyes containing a β‐sulphatoethylsulphonyl group and dispersant‐free dyeing of polyethylene terephthalate fabric

Disperse dyes containing a β‐sulphatoethylsulphonyl group have temporary solubility and can be applied for dispersant‐free dyeing of hydrophobic fibre. Six novel temporarily solubilised azo disperse dyes having a β‐sulphatoethylsulphonyl group in their structures were synthesised, and their dyeing properties on polyester were investigated. As a dye intermediate, a diazo component having dibromo groups was prepared, and 4‐diethylamino‐4′‐(2‐sulphatoethylsulphonyl‐4,6‐dibromo)azobenzene dyes were prepared by a diazo‐coupling reaction. Then, the dyes containing dicyano groups were prepared by cyanation of corresponding dyes with dibromo groups. The absorption maxima of the dyes were affected by the substituents in the diazo and coupling component rings and varied from 434 to 616 nm in dimethylformamide. Polyethylene terephthalate woven fabric could be dyed with the synthesised temporarily solubilised dyes without using any dispersants. Dyebath pH affected the K/S value at maximum absorption as well as percentage exhaustion on polyethylene terephthalate fabric, and the optimum pH was 5. The dyes gave brownish orange, red, purple, and greenish blue hues on polyethylene terephthalate fabrics, and colour build‐up was good. Wash fastness was good to excellent, rubbing fastness was moderate to excellent, and light fastness was poor to moderate.     

Colour changes of heat‐treated woods of red‐bud maple,European hophornbeam and oak

Colour evolution and colour changes were analyzed from small specimens of three heat treated wood species using the CIE L*a*b* colour space. Upon heat exposure, the wood substance became darker of species; this was accompanied by a steady reduction in lightness. As treatment conditions (e.g., time and temperature) increase, various shades of yellow were favoured for the surface of red‐bud maple wood (Δb = 1.22–9.79). For European hophornbeam wood, increased times at elevated temperatures make a blue (?b) colour the better choice. The total colour difference (ΔE) of the surfaces of wood substrates appear to be well correlated with the treatment temperature and time. The FTIR spectra suggest that the level of modification was insufficient for removing the major cell wall constituents of the wood substrates. All heat‐treated samples showed much less stability against colour difference in outdoor conditions. For red‐bud maple, the greatest improvement was achieved for samples that were treated at 150°C for 2 h (ΔE = 3.12). However, heat‐treated oak wood hadmuch less stability of colour difference for treatment conditions of 150°C for 10 h. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2010.     

Atmospheric pressure plasma‐induced decolorisation of cotton knitted fabric dyed with reactive dye

The aim of this study was to investigate the decolorisation effect of atmospheric pressure plasma treatment on knitted fabrics dyed with reactive dyes under different processing parameters, ie, air concentration, treatment duration and water content. The fabrics were dyed with reactive dye of a blue colour, and the colour depths were 0.5%, 1.5% and 3.0% on weight of fabric. The colour properties of untreated and plasma‐treated fabric samples were evaluated by means of reflectance, K/S and relative unlevelness index. The colour properties were evaluated instrumentally and quantitatively in order to study the decolorisation effect induced by atmospheric pressure plasma treatment. Experimental results revealed that the desired decolorisation effect was heavily influenced by the atmospheric pressure plasma treatment processing parameters. Although the desired decolorisation effect could be obtained by controlling the processing parameters of the atmospheric pressure plasma treatment, the treatment did not provide any significant reduction in the bursting strength of the fabric.     

Dyeing and fastness properties of phthalimide‐based alkali‐clearable azo disperse dyes on poly(ethylene terephthalate)

The properties of a series of phthalimide‐containing azo disperse dyes and azo dyes with N‐methyl phthalimide moieties in their diazo component were investigated and compared when used to colour polyethylene terephthalate. The N‐substitution of the phthalimide gave a hypsochromic effect on the colour change and better colour yields on poly(ethylene terephthalate) fabrics, probably because of the electron‐donating property of the methyl group and the higher hydrophobicity of phthalimide‐containing azo dyes compared with those containing phthalimide moieties. The results show that phthalimide‐based azo disperse dyes have excellent dyeing fastness properties and that high wash fastness can be achieved using alkali clearance. This alternative clearance method is important for reducing the environmental impact of the dyeing process by replacing reductive clearing and, in particular, by removing the need for sodium hydrosulphite, which creates a high biological oxygen demand when released in conventional disperse dyeing effluent and which generates aromatic amines.     

Publications Sponsored by the Colour Measurement Committee—IX

A new series of green paint samples has been prepared and used to study different methods of obtaining visual assessments of colour differences and of scaling the experimental results to give Δ V values directly proportional to the observed differences. The results from two standard methods (the ratio method and the paired-comparison method) were in good agreement with each other and with results from the ranking method used earlier, thus adding confidence to conclusions based on the use of the latter method. The extent of agreement between ΔE values calculated from some best-fit empirical colour-difference equations and the ΔV values has been calculated. Results obtained by Robinson on a series of blue-grey paint samples by a % acceptance method have been re-analysed. The scaling method used previously with visual results in the form of % acceptance values gives ΔV values directly proportional to calculated ΔE values. The visual observers can be subdivided into two groups based on whether they had experience of colour matching or not. No evidence was found for any difference between the ‘perceptibility’ and ‘acceptability’ of colour differences in the sense that different colour-difference equations might have been required to represent the two groups of observers.     

Preparation and properties of Fe(II)‐ion‐sensitive colour‐changing fabric

Textile fabrics were dyed with complexometric indicators (ionochromic dyes) to develop Fe(II) ionochromic fabric. Three kinds of ionochromic dye were used to dye silk fabric, and they were evaluated for colour changes triggered by Fe(II) solution. The K/S values and photos of the fabrics were then recorded. It was found that 1,10‐phenanthroline was the most suitable ionochromic dye in these dyes. Colour change from white to red could be clearly seen when 1,10‐phenanthroline‐dyed silk fabric was triggered by Fe(II) solution, but it showed no colour change when triggered by Cu(II), Mg(II), or Ca(II) solution. Moreover, 1,10‐phenanthroline‐dyed nylon, polyester, and cotton fabrics showed no obvious colour changes after triggering by Fe(II) solution. Ion concentration, pH value, and reaction time could affect the colour changes. When triggered by 8 mg l^?1 of Fe(II) solution at neutral pH for about 15 min, the ionochromic fabric showed a clear colour change. In addition, three coloured fabrics in green, blue, and yellow were also dyed with 1,10‐phenanthroline. It was found that they could also show clear colour changes when triggered by Fe(II) solution. These ionochromic fabrics may find broad application in many fields, such as Fe(II) detection, magic toys, anticounterfeiting materials, and bionic silk flowers.     

Disperse Dyes Derived from 4-Phenylazo-1-naphthylamine and 4-Phenylazo-5-hydroxy-1-naphthylamine

Application of the Bucherer reaction between 1-naphthol and alky lamines gave a satisfactory synthesis of N-substituted 1-naphthylamines. A method avoiding the use of pressurised reaction vessels, i.e. reaction of 1-naphthol with alkylamines in the presence of zinc chloride and hydrochloric acid, is reported. Coupling of diazotised 6-chloro-2,4-dinitroaniline to the above intermediates affords blue dyes which colour synthetic-polymer fibres in deep shades of generally good fastness to light and sublimation. Similar use as coupling components of 5-hydroxy-1-naphthylamines enables blue dyes to be obtained without the use of trisubstituted anilines as diazo component. Dyes thus derived from 2-chloro-2-nitroaniline absorb at longer wavelength than those from 6-chloro-2,4-dinitroaniline with analogous 1-naphthyl-amine-based couplers. Similar bathochromic shifts are observed in dyes derived from 2-methoxy-1-naphthylamines as coupling components, but these dyes have poor stability. Relationships between colour and dye structure are reported, and the use of 4-amino-1,8-naphthalimides as diazo components was additionally investigated. These give, with N-substituted 1-naphthylamines as coupling components, deep bluish-violet dyes of good fastness properties.     

Colour stability during production of printed ocular prostheses

Ocular prostheses have been used for centuries to restore patient confidence, psychosocial relationships and to improve quality of life. Methodology for producing accurate prostheses has improved with technological discoveries. Recently, hand painting ocular prostheses has been the go-to method for creating life like prostheses. However, digital printing a print to envelope around an acrylic prosthesis has been shown to decrease treatment and rehabilitation times, whilst still producing high-definition ocular prostheses. Despite these improvements, little is known about the colour stability of digitally printed ocular prostheses. To better understand the colour stability of digital prostheses 30 samples simulating ocular prostheses were created, containing 10 with blue iris, 10 combination/green iris and 10 with sepia (brown) irises. Colour measurements were taken using a data spectrophotometer, from two defined points, the iris and sclera for both pre-polymerisation and post-polymerisation to assess colour variance. Colour coordinate data was gathered and was analysed using a one-way analysis of variance test and a paired t-test, both with alpha = 0.05. Significant colour variations were found for each iris colour and for the sclera. The sclera showed the largest colour variation with a ΔE of 4.75, followed by the brown irises, the green irises and then blue irises with ΔE values of 3.29, 2.47 and 1.82, respectively. This is a significant decrease compared to current hand painting methods which have an average colour variance of ΔE = 20. This shows a large increase in colour stability which can drastically improve patient satisfaction and quality of life.     

Trichromatic dyeing of leather

It is fairly straightforward to dye textiles using a trichromatic system-that is, one which uses compatible red, yellow and blue dyes in varying proportions to give the desired colour. With leather, it is not so simple, and finding compatible dyes much more of a challenge. Here, Ray Tremlett talks about the work that has been done at Ciba on trichromatic leather dyeing.     

Monoazo disperse dyes. Part 2; Colour–constitution relationships of some novel blue disperse dyes†

Bright blue monoazo disperse dyes have been prepared by coupling diazonium salts derived from 2‐amino‐5‐nitrothiazoles on to 3‐acylamino‐N,N‐dialkylaniline based coupling components. Colour–constitution relationships of the dyes in solution and on polyester have been examined in terms of the electronic and steric substituent effects. Also the solution spectral and colorimetric data have been compared.     

Economical and Efficient Fading Lamps*

Tests have been made with over 300 dyed or pigmented materials exposed to mercury-tungsten or mercury lamps. The colorations were of a wide range of hue and light-fastness properties (1 to 8 and above) and in several depths on different substrates. The mercury-tungsten fluorescent lamp (500 W) gave results identical with those obtained with daylight or xenon arclight for 75% of the very varied selection of 174 patterns examined, and 25 % were within one-half of a grade, except for five which differed by one grade. When the blue standards are faded in this lamp (at 45% r.h.), they have an average interval factor of about 2.1. The required times of exposure are similar to those for the xenon arclight. The equipment required is extremely simple, and its initial and operating costs are considerably lower than those of methods hitherto used for testing in artificial light. The equipment can readily be used on the laboratory bench and is suitable for routine testing of the light fastness of any coloured material. In addition to the control of humidity, temperature control is possible, though this is not usually necessary. The mercury-vapour lamp (400 W) has also been similarly examined, using 138 patterns. It is not recommended for general use but is valuable for routine sorting tests of materials of very high fastness (BS grading above 7). The blue standard patterns fade, under exposure to these lamps, in the same sequence and with similar interval spacings, as in daylight or xenon light.     

Correlation between the shade of an azo disperse dye on poly(ethylene terephthalate) and poly(lactic acid) fibres with its spectroscopic properties in selected organic solvents

A series of azo disperse dyes was synthesised and the purified, synthesised dyes were characterised by proton nuclear magnetic resonance, thin‐layer chromatography and melting point measurement. The spectroscopic properties of the dyes in solution were studied by dissolving the dyes in ethyl acetate and methyl benzoate. These were seen as mimicking the environment of the dye when inside dyed poly(lactic acid) and poly(ethylene terephthalate), respectively. Reflectance spectra of the dyes on both polyester substrates were also measured in order to correlate with the spectroscopic properties of the dyes in solution. The absorbance spectra of the dyes in solution exhibited a hypsochromic (lower wavelength of maximum exhaustion) shift when dissolved in ethyl acetate, compared with methyl benzoate. The occurrence of this yellow shift was attributed to the lower polarity of ethyl acetate compared with methyl benzoate. The colour of the dyes in ethyl acetate solution was also brighter and stronger (higher molar extinction coefficients) than that in methyl benzoate. Most of the synthesised dyes exhibited high levels of exhaustion onto the two polyester fabrics. However, the visual colour yields, for those dyes having approximately the same high level of exhaustion, were different, the dyed poly(lactic acid) being stronger (higher K/S value) as well as being yellower and a trace brighter than the dyed poly(ethylene terephthalate). This difference correlated well with the solvatochromic study of the dyes in ethyl acetate and methyl benzoate solution.