Textiles screen‐printed with photochromic ethyl cellulose–spirooxazine composite nanoparticles

Photochromic compounds change colour on exposure to light, while the reversion may be attributable either to radiation or may be thermal. The use of photochromism on fabrics can provide new opportunities to develop smart textiles; for example, sensors and active protective clothes. Ethyl cellulose‐1,3‐dihydro‐1,3,3,4,5 (and 1,3,3,5,6) ‐pentamethyl‐spiro‐[2H‐indole‐2,3′‐(3H)naphtha(2,1‐b)(1,4)oxazine] composites were prepared by an oil‐in‐water emulsion, solvent evaporation method in order to form easily suspendable and fatigue‐resistant photochromic nanoparticles in screen‐printing paste. Their size was well below 1 μm and did not change substantially over a wide range of dye concentrations. After screen‐printing, a homogenous photochromic layer was built on a cotton substrate surface, which represented substantial blue colour development in CIELab colour space measurements because of ultraviolet light, even at a dye concentration of 0.045% w/w. The addition of a photodegradation inhibitor, Tinuvin 144, further increased the coloration of the printed fabric.     

Colour management of a low‐cost four‐colour ink‐jet printing system on textiles

A low‐cost four‐colour (RBYK) dye‐based ink‐jet printing system for textiles was introduced in this study, in which red and blue inks were employed instead of the magenta and cyan inks used in half‐tone printing. The basis of a colour‐management system for this device was developed by determining the mapping between XYZ tristimulus values of output colours and the digital RBYK values using polynomial transforms. A second‐order equation was found to give the best performance with an average characterisation error of under 7 CIELAB units.     

Colour matching for smart and sustainable spinning of coloured textiles

The colours and patterns of coloured textiles are usually obtained via dyeing or printing processes. However, these processes consume large amounts of electricity and cause water pollution, which affects the ecological environment. The hand feel of dyed fabrics is superior to that of printed fabrics. Three‐channel rotor spinning is a highly flexible, adaptable and sustainable method for producing coloured textiles by blending precoloured fibres during the spinning process. Additionally, the process requires approximately half the water required for fabric dyeing or printing. Herein, the colour characteristics, as well as the advantages, of the coloured textiles produced by the new method are demonstrated. Three types of Stearns‐Noechel models are modified to describe the relationship between the blending ratios and resulting textile colours. The colour‐matching accuracy is high. As demonstrated by the results, the three‐channel rotor spinning method can effectively promote coloured textile engineering.     

Properties of ink‐jet printed,ultraviolet‐cured pigment prints in comparison with screen‐printed,thermo‐cured pigment prints

A collection of printed fabrics for men’s shirts was designed and prepared using computer‐aided design/computer‐aided manufacturing technology. The colours for designs were ink‐jet printed on cotton fabrics with pigments and ultraviolet‐cured. These prints represented the target colours for subsequent flat‐screen printing, which was performed using pigment printing pastes and thermal curing. For an exact transfer of colours of the ink‐jet‐printed standard into the screen‐printing process, a computer recipe prediction method was used. A comparison of colorimetric parameters of fabrics printed with both printing techniques shows minimal and acceptable differences in the CIELab colour values. A comparison of colour fastness properties proves that very good colour fastness is achieved on the pigment‐printed fabrics produced with both printing techniques. The flat‐screen‐printed fabrics show better colour fastness to washing, perspiration and rubbing, while ink‐jet‐printed fabrics show better colour fastness to dry‐cleaning and light. The fabrics printed with both printing techniques have high rigidity and non‐elastic properties. The mechanical and physical parameters are strongly dependent upon the amount of the dry substance of the printing media applied on the cotton fabric surface, which is higher on screen‐printed fabrics. The ink‐jet‐printed fabrics show better air permeability than flat‐screen‐printed fabrics.     

Textile applications of photochromic dyes. Part 2: factors affecting the photocoloration of textiles screen‐printed with commercial photochromic dyes

The performance of five commercial photochromic dyes applied by screen printing on textiles was evaluated using a colour measurement methodology which has previously been established and validated. Printing as disperse dyes on polyester gives the strongest photochromic effect when the dye is located near the surface. However, the dyes are applied more effectively using an adaptation of a pigment printing method. Several factors influencing the photochromic properties of the printed textiles were evaluated. The ultraviolet reflecting properties of cotton give a higher level of photocoloration than on polyester. In the dyes studied, the spirooxazines show slightly faster colour development and fade much more rapidly than the naphthopyrans, and the latter show a residual colour after fading. The effect of the ultraviolet irradiation wavelength profile on the photochromic response may be correlated with the ultraviolet absorption spectra of the dyes.     

Photocatalytic degradation of organic dyes by a donor–acceptor type conjugated polymer: poly(thiophene‐1,3,4‐oxadiazole) and its photocatalytic mechanism

A donor–acceptor conjugated‐type polymer, poly(thiophene‐1,3,4‐oxadiazole) (PThOD), was synthesized by one‐step polycondensation in polyphosphoric acid. PThOD was confirmed and characterized using Fourier transform infrared spectra, thermogravimetric analysis, X‐ray diffraction and UV‐visible spectra. The UV‐visible spectra showed that PThOD could absorb not only in the whole ultraviolet range from 200 to 400 nm but also in the visible light range up to 500 nm. Considering the conjugated structure of PThOD, studies were carried out of its performance for the photocatalytic degradation of various dyes, such as methyl orange, methylene blue, rhodamine B and reactive brilliant blue (RBB), under medium‐pressure Hg light source irradiation. The results showed that PThOD was an effective photocatalyst, which could degrade the four types of dye solution. Besides, visible light was also used to investigate the degradation of RBB, and the results showed that RBB could be degraded as well, though the efficiency was not as high as using the Hg lamp. The superoxide anion radical (O₂^??), which is one of the reactive oxide species, was detected using the nitrotetrazolium blue chloride method and considered to play a key role in photodegradation of dyes. Moreover, various scavengers were also used to further prove the function of ^?. Furthermore, it was found that degradation rate could be changed by adding H⁺, which might be attributed to a change of adsorption capacity of PThOD. Finally, the reusability of PThOD as photocatalyst was investigated. The results indicated that the reusability efficiency of PThOD was excellent even after ten continuous rounds of use. © 2018 Society of Chemical Industry     

Textile applications of photochromic dyes. Part 3: factors affecting the technical performance of textiles screen‐printed with commercial photochromic dyes

The technical performance of five selected commercial photochromic dyes applied by screen‐printing on textiles was evaluated using a colour measurement methodology that has previously been established and validated. The results of wash fastness assessments were distinctly unusual. With the selected spirooxazine dyes, the degree of photocoloration increased with initial washing and decreased with subsequent washings, while the naphthopyrans behaved more normally, showing a consistent marginal decrease in photocoloration with repeated washing. An explanation is proposed consistent with scanning electron microscopy examination of the binder film degradation and with the structural differences between the dye classes. The dyes in this application showed limited photostability. The incorporation of ultraviolet absorbers was found to increase photostability only to an extent specific to particular ultraviolet absorber/dye combinations. However, the presence of the ultraviolet absorber led to a consistent reduction in the degree of photocoloration of the dyes. In contrast, the incorporation of hindered amine light stabilisers significantly enhanced the photostability of the dyes, providing an increase in resistance to photodegradation of up to fivefold.     

Developing the methodology of colour gamut analysis and print quality evaluation for textile ink‐jet printing: Delphi method

This research used the Delphi method to investigate current colour gamut analysis methods, which is a critical component of colour management systems (CMS). Thirteen ink‐jet printing experts were interviewed to understand how they manage colour and their process for analysing and comparing colour gamut. A significant result of this study was the development of a four‐stage process model for colour gamut analysis and print quality evaluation for textile ink‐jet printing. The optimal process model was verified and approved by experts. This study uncovered an industry initiative toward the improvement of CMS for more accurate colour matching, a need to stabilise variables in the manufacturing process, and a need to standardise related tests and evaluations. The study also revealed new CMS software and technologies developed for ink formulation and pre‐/post‐treatment methods to facilitate high quality production in textile ink‐jet printing.     

Effect of texture on color variation in inkjet‐printed woven textiles

Inkjet‐printed textiles are influenced by a wide range of parameters due to highly diverse textile structures and the resulting textures. The goal of this study is to understand the effect of texture on color appearance in inkjet‐printed woven textiles. Cotton‐woven samples were constructed with nine different weave structures. Each sample was digitally printed with identical squares of primary colors cyan, magenta, and yellow and secondary colors red, green, and blue. The amount of ink applied was controlled consistently with an image editing software. CIE L* values were calculated from the measured reflectance. 25 observers ranked the perceived texture and color lightness of each sample. Perceived visual texture and perceived color lightness scales were estimated from the rankings using the rank order method. The measured CIE L* values and the scale of perceived lightness were positively related for the primary and secondary colors. Instrumental measurements of the textile surface characteristics were positively related to the visual scale. Texture was demonstrated to cause a measurable effect on color results in inkjet printing, both using instrumental and perceptual measures. To investigate if the color differences were substantial enough to cause “out of tolerance” ratings in textiles based on common textile industry color acceptance procedures, color differences among the samples were calculated and compared to a reference sample. Results demonstrated that color variation due to texture was sufficient to lead to rejection of a printed color in comparison to a color specification. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 297–303, 2015     

Preparation and characterization of UV‐grafted ion‐exchange textiles in continuous electrodeionization

Ion‐exchange textiles (IETs) suitable for use in continuous electrodeionization (CEDI) stacks were prepared using the ultraviolet (UV)‐induced grafting of acrylic acid and sodium styrene sulfonate for cation‐exchange textiles, or 2‐hydroxyethyl methacrylate and vinylbenzyl trimethyl ammonium chloride for anion‐exchange textiles, onto nonwoven polypropylene fabric using benzophenone as photoinitiator. Although the ion‐exchange capacity (2.2 meq g^?1) of the prepared strong acid cation‐exchange textile was lower than that of IRN77 strong acid cation‐exchange resin (4.2 meq g^?1), the overall rate constant of IET was very high due to its low crosslinking and high specific surface area. There was no significant difference between the two different media in terms of the Co(II) removal rate. Furthermore, the current efficiency for IETs was higher than that of IRN77 cation‐exchange resin during a CEDI operation, with efficiencies of 60% and 20%, respectively. The IET also showed the faster exchange kinetics. Therefore, IETs prepared in this study proved to have desirable ion‐conducting characteristics within the CEDI systems. Also this study revealed that the primary removal mechanism in CEDI is the transport of ions through a medium and not the ionic capacity of a medium. Copyright © 2004 Society of Chemical Industry     

The effect of different radiation sources for the UV curing of a screen‐printed,water‐based polyurethane acrylate binder

In this paper, titanium‐dioxide‐pigmented printing pastes of water‐borne, UV‐curable polyurethane acrylate binder with two different UV‐curing photoinitiator combinations were prepared and screen printed on a black t‐shirt fabric. The effects of mercury and gallium radiation sources employed either singly or in combination for UV curing and the total energy level on the printing performance were investigated. The cured textile samples were subjected to colour measurements before and after five cycles of washing, and hiding power and changes in chromacity, hue, and colour were determined. Single‐lamp applications of mercury and gallium were not satisfactory, and opaque pigment hindered deep curing, especially at thicker coating levels. It was found that employment of a mercury–gallium lamp system applying an irradiation at medium level can provide pigment printing of opaque white inks with excellent coverage, washing resistance, and medium hardness.     

Ink‐jet printing of cotton with natural dyes

Four natural dyes, annatto, cutch, pomegranate fruit rind, and golden dock, were used as colorants for the preparation of water‐based ink‐jet inks for digital textile printing. The physical and rheological properties (pH, conductivity, surface tension, and viscosity) of the inks were measured over a period of 90 days for the evaluation of ink stability and suitability for ink‐jet printing. The inks were found to be suitable and were used for the digital printing of cotton fabrics. The prints were subjected to wash, light, and rub fastness tests and colour measurements. Colour consistency and fastness results, especially after fixation, are comparable with those of synthetic dyes, which paves the way for the production of environmentally friendly ink‐jet inks using natural dyes for the digital printing of cotton through the formulation of suitable printing techniques.     

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.     

John Mercer FRS,FCS, MPhS,JP: the Father of Textile Chemistry

John Mercer (1791–1866) was a pioneering textile and colour chemist with a legacy of achievements. His invention of mercerising that bears his name, treating cellulosics with sodium hydroxide to bring about advantageous changes in fibre and fabric properties, will stand for all time as one of the most important textile chemical treatments ever developed. However, Mercer's contributions to the textiles and coloration industries went far beyond mercerisation. A self‐taught chemical experimentalist par excellence, his keen observations and interest in calico printing led to many novel developments, such as his work on Chrome Yellow and other ‘mineral colours’. Mercer developed new methods for fixing Prussian Blue on calico and wool, developed new mordants for dyeing, improved the extraction of carminic acid from cochineal, and improved the oiling process in Turkey Red dyeing. He saved lives with his research into early antimicrobials, preventing the spread of cholera in textile villages in Lancashire. Mercer was an unsung hero of early photography, and developed light‐sensitive imaging materials and made some of the earliest recorded monochromatic colour photographs. His forward‐looking views on technical education, that workers in the industry should be fully instructed in the nature of the various substances used in their arts, later came to fruition in the establishment of the textile departments in Manchester, Leeds and Glasgow. To this day, Mercer remains the only textile chemist who has ever been elected as a Fellow of the Royal Society since 1852. He is thus quite rightly considered as the Father of Textile Chemistry.     

Pretreatment effects on pigment‐based textile inkjet printing – colour gamut and crockfastness properties

The application of two commercial pretreatment agents, formulated to improve the performance of a six‐colour nano‐scale pigment ink set during the textile inkjet printing of cotton and polyester (PET) fabrics, was examined. An industrial scale printer, operating at 55 linear m/h and equipped with Kyocera printheads, was used to print on commercial fabrics (180 cm wide) prepared for digital printing. The work employed an industrial scale rather than a benchtop printer to enhance the utility of the results for a commercial environment. The colorimetric attributes of printed fabrics were recorded for the individual inks as well as for spot colour combinations generated using Dr. Wirth RIPMaster v11 software. Colour table profiles were also generated and the colorimetric values of inks were compared. Colour gamuts of inks on cotton and PET, including three‐dimensional volumes in the CIELab space, were examined to assess the role of pretreatment on the colorimetric properties of the printed substrates. It was found that the pretreatments enhanced the ink receptiveness, colour intensity and colour gamut of fabrics. Pretreatment of cotton resulted in a larger gamut and more vivid colours than on PET. However, wet and dry crockfastness results were found to be low. In this regard, Time‐of‐Flight Secondary Ion Mass Spectrometry analysis of fabrics printed in the presence and absence of pretreatment indicated that the low crockfastness arises from higher pigment levels on the surface of the pretreated fabric.     

Preparation of coated thermo‐regulating textiles using Rubitherm‐RT31 microcapsules

Spherical microcapsules with a 49 wt % of Rubitherm^® RT31 were successfully synthesized by means of suspension‐like polymerization to be used for textile applications in summer conditions. Microcapsules were fixed into seven fabric substrates for different textile applications by a coating technique without deteriorating original functionalities of the textiles. Thermal performance of different coated textiles with 35 wt % of microcapsules was evaluated by differential scanning calorimetry (DSC) and infrared thermography (IR) techniques and the physical characteristics of textiles with thermo‐regulating properties were examined by environmental scanning electron microscopy (ESEM). It was observed that all treated textile substrates allow to obtain thermo‐regulating properties with acceptable latent heat storage capacities. Results also indicated that the presence of microcapsules containing Rubitherm^® RT31 produces a significant thermal insulation effect during a cold to warm transition (20–45°C). Thus, this kind of microcapsules can be used to obtain textiles with thermal comfort‐related properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Investigation into the development of novel lanthanide-based luminescent colorants for application to textiles and paper materials

This article describes the synthesis and application of lanthanide-based luminophores for visualisation under short wavelength ultraviolet (UV) activation (typically 254 nm). Luminophores are chemical compounds which re-emit light of longer wavelength than typical fluorescence and phosphorescence, following photoexcitation, because of efficient energy transfer from the ligands to the lanthanide ion emission levels. The luminophores described in this article are all derived from europium and terbium metal complexes and cover the complete colour gamut. Selection of appropriate ligands allows for water solubility or water insolubility (if required pigment or disperse “dye” applications). Similar to dyeing or printing processes, the anionic complexes can be applied to polyamide fibres or to cellulosic fibres, whereas dispersions of the non-ionic complexes are suitable for polyester or cellulose acetate fibre application. The water-soluble derivatives are also suitable for ink-jet printing and the water-insoluble derivatives are suitable for lithographic or intaglio paper printing. The novel complexes are excited by radiation below 300 nm and thus cannot be activated by sunlight (the earth's atmosphere prevents light below about 300 nm reaching the surface). Accordingly, the photo-stability of the dyed materials and prints obtained is excellent. These materials could be used in security marking applications, for example bank-notes and passports, where they could replace the current fluorophores that are rendered visible under near UV light (typically 365 nm) illumination but exhibit relatively poor photo-stability. The development of an RGB (red, green and blue) colour palette for inkjet printing based on these innovative luminophores will significantly support the design of digitally printed security features.     

Direct coloration of textiles with photochromic dyes. Part 2: The effect of solvents on the colour change of photochromic textiles†

Polyester, acrylic and nylon textile substrates dyed with two spirooxazine dyes, 1,3,3‐trimethyl‐spiroindoline‐2,3′‐3H‐naphth[2,1‐b][1,4]oxazine ( 1a ) and 6′‐piperidino‐1,3,3‐trimethyl spiroindoline‐2,3′‐3H‐naphth[2,1‐b][1,4]oxazine ( 1b ), exhibit significantly higher photochromic colour build‐up when wet compared with after drying. A study of this phenomenon, extended beyond water to the influence of a series of selected organic solvents on photochromic behaviour, using colour measurement of the photochromic textiles under controlled ultraviolet irradiation conditions, is reported. The results of molecular modelling calculations (AM1 in water and PM5 in water) have been used as a means of interpreting the observed effects, in conjunction with qualitative arguments based on solvation and fibre swelling.     

Determination of bicomponent dye solutions by means of zero‐crossing‐point derivative spectrophotometry

In this study, a new spectrophotometric method was developed for the determination of some textile dyes with different types of overlapping spectra. The binary mixtures of five dyes with yellow, scarlet, red, blue, and navy blue colors were analyzed by zero‐crossing‐point first‐derivative spectrophotometry. The absorption spectra of the mixtures prepared in different ratios were recorded between 400 and 700 nm. First derivative amplitudes at appropriate zero‐crossing wavelengths were selected for the determination of dyes in the mixtures. The proposed method was successfully applied to the determination of dyes with overlapping spectra in their bicomponent mixtures. The proposed derivative method is simple, rapid, and suitable for quantitative analysis of bicomponent dye solutions. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 307–311, 2008.     

Research of influences of surface structure of coloured textiles: applying fuzzy logic

The fuzzy logic‐based approach was applied in studying the influence of a different textile surface structure on colour appearance and similarity. The fuzzy‐based approach has been chosen because fuzzy logic provides the computerising of human reasoning. For the analyses, 100% cotton samples with certain characteristics were chosen. First, the computer match prediction was performed to determine the concentrations of dyestuff to be used in the experimental work. A yellow‐shaded direct dyestuff suitable for cotton dyeing was used. In the next step, the fuzzy logic system was created based on terms that would define the surface characteristics of the samples. The most important part was a proper definition of the rules and linguistic variables that use words for assigning the values of properties and that influence the experience of an observer (gloss, smoothness, roughness, etc.) and connect input space with output space. Finally, the performances of both systems were compared and analysed. In this work, the approach was based solely on the surface–structural characteristics of textile samples. The main aim was to examine the approach using the fuzzy logic‐based technique in order to provide the method that would include surface parameters of textile samples that are of importance in applying colour to different structured textile surfaces. It was confirmed that the fuzzy logic reasoning would have its application in the control of the influence of the surface structure of coloured textiles, especially for lighter shades where the influence of structure parameters on the colour experience of an observer is more emphasised.