Dyeing of cationised cotton with acid dyes

The production of cationised cotton fabrics, via Sandene 8425, 1, 1-dimethyl-3-hydroxy azetidinium chloride and 1, 1-diethyl-3-hydroxy azetidinium chloride, greatly enhances the exhaustion and fixation of acid dyes. This paper shows that these dyes can be used in the absence of salt in a neutral medium. Wash fastness, light fastness and other properties were studied.     

Ink-jet printing of cationised cotton using reactive inks

The ink-jet printing properties of cotton cationised with 2,3-epoxypropyltrimethylammonium chloride have been studied. Cyan, magenta, yellow and black reactive inks were used to print untreated and cationised cotton fabrics. The effect of cationic reagent concentration, steaming time, ink (colour) and print resolution were investigated, together with possible differences between the behaviour of the four inks. Colour yields, staining of the white grounds, penetration behaviour, print quality and fastness properties were evaluated.     

Printing of cationised cotton with reactive dyes

The printing properties of cationised cotton that had been pretreated with 2,3-epoxypropyltrimethylammonium chloride were examined. Fixation (steaming) time, colour yields, colorimetric properties, fastness properties, staining of the white grounds and penetration behaviour were evaluated for a number of reactive dyes with cationised cotton fabrics. The cationisation of cotton was found to be very effective in reducing steaming times and washing off processes, and in increasing colour yield. Fastness and other properties of the printings are also discussed.     

Continuous dyeing of cationised cotton with reactive dyes

Cotton fabrics pretreated with cationic starch have been dyed with reactive dyes by a continuous dyeing method and the pretreatment conditions influencing dyeability of the treated cotton investigated. Cationised cotton has been found to give level dyeing without the presence of salt and dye fixation is improved compared with untreated cotton. The dyeings show good wash and rub fastness.     

Improving the environmental and economic aspects of cotton dyeing using a cationised cotton†

One approach to improve the affinity of anionic dyes for cotton is to add cationic dye sites to the fibre. The dyeing behaviour of cotton that had been rendered cationic by reaction with 2,3‐epoxypropyltrimethylammonium chloride was examined. Dye yields and fastness properties are reported for a number of direct, reactive and acid dyes with the modified fibre. Excellent dye yields and colour fastness properties were obtained without the use of electrolytes, multiple rinsings or fixation agents which are normally employed in cotton dyeing.     

Adsorption behaviour of carbon black/latex by cationised cotton fabrics

A carbon black/latex dispersion was prepared by mini‐emulsion polymerisation, and its absorption behaviour towards cationised cotton fabric was investigated. The results indicated that the prepared carbon black/latex dispersion had excellent freeze–thaw stability. Cotton fabric that was cationised with 3 g/l of 3‐chloro‐2‐hydroxypropyltrimethyl ammonium chloride at a liquor ratio of 30:1 can be optimally dyed with 4% owf carbon black/latex under the conditions of pH 7.2, 60 °C, and 1 h. The adsorption behaviour of the carbon black/latex towards cationised cotton fabric followed the Langmuir adsorption isotherm, with a lower dyeing rate and a better colour levelness than the ordinary carbon black dispersion with binder.     

Influence of liquor ratio and amount of dyestuff in producing ultradeep black dyeing using mercerised and cationised cotton

Cationised cotton allows the dyeing of cotton fabrics without salt and up to 100% anionic dye utilisation. The employment of cationised cotton in the dyeing of high depths of shades with reactive dyes holds marked potential for sustainable improvements through less dye consumption, decreased water usage, and zero salt utilisation, all while obtaining shade depths darker than possible with conventional reactive dyeings. This work builds upon previous work in obtaining ultradeep dyeings of cotton utilising cationised and mercerised cotton by investigating the effects of liquor ratio in dyeing and amount of dye applied. Surprisingly, for mercerised only cotton fabric, it was found that nearly equivalent depths of shade, as indicated by L*, were obtained, irrespective of the liquor ratio and the amount of CI Reactive Black 5 applied from 7% to 10% owf. However, the strengths of the dyeings, indicated by the K/S sum, show slight increases with increasing amounts of dye, but not when the liquor ratio is lowered. Similarly, for mercerised‐cationised cotton, the liquor ratio had a negligible effect on the depth of shade obtained, but increasing the amount of CI Reactive Black 5 resulted in an increase in shade depth and colour strength. Very deep shades with high colour strength were obtained with mercerised‐cationised cotton that were not obtainable with uncationised cotton, even at a very low liquor ratio and with a drastic increase in the amount of CI Reactive Black 5.     

Optical whitening of cationised cotton: effect on whiteness and whiteness tint

In this study, the effect of cationisation on optical whitening was examined. For this purpose, the whiteness index and whiteness tint of optically whitened pre‐cationised knitted cotton fabrics were analysed. The cationisation and optical whitening processes were carried out under different concentration levels, using the exhaustion method. The whiteness index and whiteness tint were calculated after colour measurements were taken. The experimental results were also analysed statistically using ANOVA. The whiteness index obtained from cationised fabric was lower than that of non‐cationised fabrics. While the whiteness tint of cationised cotton fabric had a blue to greenish nuance, the non‐cationised fabric had a reddish nuance.     

Dyeing cotton in short-liquor jets

The emergence of short-liquor jets for dyeing cotton and its blends has been marked over recent years. Not only does this process offer the possibility of more economical dyeing, but it also reduces the load inflicted on the environment Kurt Bacher discusses the problems associated with short-liquor dyeing and how to overcome them.     

Dyeing of cotton with indigo using iron(II) salt complexes

The use of gluconic acid as a ligand for complexing iron(II) salts and for vat dyeing of cotton has been reported previously. The present paper reports the observations on the use of iron(II) salts complexed with such ligands as tartaric acid and citric acid for the reduction of indigo at room temperature and subsequent cotton dyeing. This study includes the measurement of reduction potentials of various iron complexes, their effect on dye uptake and the deposition of iron on dyed fabric.     

Investigation of the improved dyeability of cationised cotton via photografting with UV active cationic monomers

In this study cotton fabric was photografted with cationic monomers using UV radiation. The dyeability of cationised cotton, in the absence of salt, with three classes of dye (direct, reactive and sulphur dyes) was significantly improved due to the increased ionic attraction between the dyes and the cationic cotton. The colour fastness of the cationised fabric was similar or better than that of the untreated fabric. In addition, when cationised, crosslinked crease-resist cotton also showed improved dyeability, in the absence of salt, to direct dyes.     

Stability of pigment and resin dispersions in waterborne paint

The stability of a colloidal dispersion in a waterborne paint system, which consists of dispersed pigment and polymeric particles (dispersion or emulsion) along with a water-soluble acrylic polymer, was investigated. It was found that adsorption of appropriate ultrafine particles to the relevant particles could stabilize these particles against flocculation, leading to lower viscosity and yield value. The gloss and smoothness of the resultant films are notably improved. As the stability of the colloidal particles in an aqueous system is strongly dependent on the electrostatic effect, the effect was evaluated by measuring the ζ-potentials of the relevant colloidal particles. The ζ-potential is the electric potential on the outside of the surface layer, which includes the counterions around the particle. The ζ-potentials of a series of pigments in a solution of a water-soluble polymer were determined. By arranging the pigments according to their ζ-potentials, an order of basicity-acidity was established for pigments in a waterborne system, and the order was found to be different from that of solventborne systems, thought to be due to adsorbed counterions. After dispersing the pigment sufficiently with an appropriate polymer dispersant, ultrafine particles (of size under 0.05 μm) of lower refractive indexes were adsorbed to the surface of the pigments and polymeric particles. The adsorption layer of ultrafine particles can modulate the ζ-potentials of various colloidal particles to bring them into a certain range, so that the co-flocculation tendency between different colloids is remarkably diminished providing quite stable paint compositions by both electrostatic and steric hindrance effects.     

Hindered settling of organic pigment dispersions in hydrocarbon liquids

A modified Steinour hindered settling method has been developed for the study of dispersed organic pigment species containing a large proportion of associated immobile liquid. These species are termed flow units with effective volumes and densities different from those of the pigment itself. The effective volume and density are calculated from the final sediment volume fraction after correction (if practicable) by an appropriate packing factor. The mean flow unit diameter (or a size parameter) can then be estimated. The present method has been satisfactorily tested using formalin-fixed yeast cells as model flow units which can be sized readily by optical microscopy. Data for organic pigment dispersions compare well with their appearance under the optical microscope. Various uses of simplified versions of the present technique in studies of dispersibility and dispersion stability of organic pigments are described and exemplified using mainly copper phthalocyanine pigments in hydrocarbon solvents.     

Hindered settling of organic pigment dispersions in hydrocarbon liquids

A modified Steinour hindered settling method has been developed for the study of dispersed organic pigment species containing a large proportion of associated immobile liquid. These species are termed flow units with effective volumes and densities different from those of the pigment itself. The effective volume and density are calculated from the final sediment volume fraction after correction (if practicable) by an appropriate packing factor. The mean flow unit diameter (or a size parameter) can then be estimated. The present method has been satisfactorily tested using formalin-fixed yeast cells as model flow units which can be sized readily by optical microscopy. Data for organic pigment dispersions compare well with their appearance under the optical microscope. Various uses of simplified versions of the present technique in studies of dispersibility and dispersion stability of organic pigments are described and exemplified using mainly copper phthalocyanine pigments in hydrocarbon solvents.     

水性易分散环保颜料的制备

以颜料合成后经过洗涤的滤饼为母体,通过添加颜料衍生物、组合分散剂然后进过特殊干燥或者易分散环保颜料。该颜料系列可以用于水性各种用途,包括水性涂料、油墨以及其他水性分散体。     

Preparation of nanoscale azo pigment yellow 13/poly(styrene–maleic acid) composite dispersions via free‐radical precipitation polymerization

Nanoscale azo pigment yellow 13 (PY13) was coated by poly(styrene–maleic acid) (PSMA) with a free‐radical precipitation polymerization, followed by the preparation of the dispersion. The effects of the PSMA structure on the particle size and centrifugal stability were investigated. The experimental results revealed that the particle size was large, and the stability of the PY13/PSMA dispersions was high when the molar ratio of the feeding maleic acid to styrene, the weight ratio of the feeding initiator to monomer, and the weight ratio of the feeding monomer to pigment were about 1.0, 0.6, and 20%, respectively. Fourier transform infrared spectroscopy, dynamic light scattering, and transmission electron microscopy indicated that PY13 was coated by PSMA. The PY13/PSMA dispersion was stable in the pH range 5.6–10.5. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010