Alkylaminoanthraquinones as dyes for polypropylene fibres

The synthesis of a series of 1-alkylaminoanthraquinones is described. In general, dyeing properties and light fastness of these compounds on unmodified polypropylene fibres improves with increase in length of the alkyl chain. The presence of the n-octadecylamino group is particularly advantageous and a range of new dyes containing this substituent is described.     

Dyeing as-spun polypropylene fibres with disperse dyes using periodic technology

The major possibility of dyeing PP fibres medium hues with disperse dyes using periodic technology was demonstrated. It was found that dyeing as-spun PP fibres ensures diffusion of the dye inside the fibre material. Use of Neonol AF 9/6 nonionogenic wetting agent during dyeing increases the amount of dye sorbed by PP fibre material. Translated from Khimicheskie Volokna, No. 1, pp. 24-26, January-February, 2008.     

Physical modification of polypropylene: preparation of fibres dyeable with disperse dyes

Published literature from the past 30 years concerning the removal of dyes from textile effluent has been reviewed. The relationship between the bioelimination by activated sewage sludge and the molecular structure of anionic, water-soluble dyes has been examined. Bioelimination of many commercially available dyes as a mechanism for decolorising textile waste waters has been shown to be an inefficient process. However, the information collated will be used as the basis for development of novel reactive dyes for potential commercial application.     

Controlled coloration: a success strategy for the dyeing of cellulosic fibres with reactive dyes

The impact of improving the rate of right-first-time production on productivity and profitability for a batchwise dyehouse processing cellulosic fibres is reviewed. The measurement and level of performance required from reactive dyes to support right-first-time production is defined in the form of a reactive dye compatibility matrix (RCM). The application of the RCM as a diagnostic tool in dye selection and process design is outlined.     

The adsorption of pyrazolone acid dyes by polyamide fibres

Investigations of the adsorption of acid dyes (l–phenyl–3–methylpyrazolone derivatives) by polyamide fibres have been carried out. It has been found that the adsorption levels are unexpectedly different for various dyes. Some of the dyes, despite high concentration in the dyebath, show adsorption within the limits of what would be predicted by consideration of the amino group content in the amorphous region of the fibre. Other dyes, despite high pH, are characterised by considerably higher adsorption than would be predicted. The results obtained suggest that the increased adsorption of the dyes is brought about by the aggregation of molecules in the fibre into dimers or their multiples.     

Disperse dyeing of methacrylic acid grafted polypropylene fibres

The dyeing behaviour of methacrylic acid grafted polypropylene fibre with a disperse dye (Dispersol Red B-3B) under infinite dyebath conditions has been evaluated. It was found that uptake of dye by the fibre is considerably improved by grafting. The rate of dyeing and the diffusion coefficient also showed marked increases in the grafted samples. Theresults have been explained in terms of the structural changes in the fibre effected by grafting.     

Dyeing of N-modified viscose rayon fibres with acid and metal-complex dyes

Viscose rayon N -modified by the incorporation of polydiallyldimethyl ammonium chloride gave good dye exhaustion and colour yield on dyeing with acid or metal complex dyes. The amount of additive present in the fibre was assessed from its nitrogen content, and percentage exhaustion was found to increase with increasing quantity of additive. Changes in hue, in addition to an increase in the light fastness of deeper shades, are attributed to aggregation of dye within the fibre. The light fastness of metal complex dyes on N -modified fibre was very good but acid dyes gave poor results. Wash fastness was improved after treating with a dye fixing agent.     

Direct coloration of textiles with photochromic dyes. Part 3: dyeing of wool with photochromic acid dyes

Wool dyed with two isomeric water‐soluble spirooxazine‐based photochromic acid dyes, which were specifically designed and synthesised for direct application to protein and polyamide substrates, showed reversible change from a pale yellowish colour to blue when exposed to sunlight or UV light. With the first dye, significantly higher photochromic colour change was obtained when the wool was bleached, a feature attributed to a more open fibre structure which may facilitate penetration of the non‐planar dye anion and also the photocoloration reaction which requires a change in molecular geometry. Experimentation demonstrated that the optimum conditions for application of this dye to wool was from an aqueous dyebath at neutral pH and a temperature of 60 °C. An investigation using HPLC demonstrated that the dye was susceptible to decomposition in aqueous solution at higher temperatures and at lower pH values. The second dye was also applied to wool fabric to give a fabric with similar photochromic properties. The technical performance of the dyed fabrics, in terms of washfastness and photostability, was assessed.     

Anionic coloration of acrylic fibre. Part 1: Efficient pretreatment and dyeing with acid dyes

Anionic dyeable acrylic fibre has been obtained by a viable and efficient pretreatment process using hydroxylamine hydrochloride in the presence of acetate salt. The chemical modification relies on an amidoximation reaction that partially converts cyano groups present in the fibre to amidoxime groups. Different factors that may affect the pretreatment process have been investigated. The pretreated fabrics were dyed with CI Acid Red 1 and CI Acid Green 16 and gave improved dyeability over untreated fabrics due to the ion–ion interactions between the sulphonic groups present in the dye molecules and the protonated amino groups present in the fibres. The treated dyed fabrics also showed excellent fastness properties. Fibre characterisation (nitrogen content, tensile strength, shrinkage, infrared spectra and X-ray diffraction) proved the success of the amidoximation reaction.     

Modification of polypropylene fibres with cationic polypropylene dispersion for improved dyeability

Polypropylene (PP) fibres are important hydrophobic fibres which are used in the production of functional textiles such as sports textiles. The absence of functional groups and low polarity make PP fibres difficult to dye, thus mass coloration during fibre extrusion is the major technique applied today. However, the disadvantage of mass coloration is the low flexibility and the demand to produce high volumes. A new method to modify the surface of PP fibres utilises the deposition and thermal fixation of cationic PP dispersion. Through padding and thermal fixation of a cationic PP dispersion, dyeable 100% PP fibres can be obtained. The effects of fixation temperature, and of the amount of dispersion used on the modified fibres were studied using Fourier Transform‐infrared spectroscopy, laser scanning microscopy, dyeing experiments with CI Acid Red 151, and by determining selected fastness properties. The results indicate the potential of this new method to produce surface‐modified 100% PP fibres, which can be dyed in conventional acid‐dyeing processes and therefore used in fibre blends, for example in combination with wool.     

Dyeing of poly(lactic acid) fibres with synthesised novel heterocyclic disazo disperse dyes

Poly(lactic acid) (PLA) is the first melt‐processable, renewable, sustainable and biodegradable natural‐based synthetic fibre. It has a broad range of uses and combines ecological advantages with outstanding performance in textiles. PLA fibre, as an aliphatic polyester, can be dyed with disperse dyes. Apart from the limited number of commercial disperse dyes, disperse dye exhaustion on PLA is generally lower than that on  poly(ethylene terephthalate) (PET). In this study, new heterocyclic disazo disperse dyes, substituted with methyl, nitro and chloro groups at their ortho‐, meta‐ and para‐ positions, synthesised in our previous study, were applied to PLA and PET fibres to examine their dyeing performance, and colour fastness and dye exhaustion properties. Different shades of yellow, orange, reddish brown and brown were obtained. Most of the synthesised novel heterocyclic disazo disperse dyes exhibited good build‐up properties with high K/S levels on both fibres. Para‐ bonding substituent provided higher K/S values than meta‐ and ortho‐ positions for –NO₂ and –Cl substituents for both fibres. Overall, the most synthesised novel heterocyclic disazo disperse dyes in this study exhibited good build‐up properties with high K/S, exhaustion and wet fastness levels on both PLA and PET fibres.      

The dyeing of poly(lactic acid) fibres with disperse dyes using ultrasound: Part 2 - Fastness

The use of ultrasound imparted greater colour strength to 1% omf dyeings of five of six disperse dyes studied, both before and after reduction clearing and had no effect on either the colour or λ_max of the dyeings. The lower fastness obtained to both wet and dry rubbing as well as to the first two/three of the five repeated wash cycles was attributed to the greater colour strength of the dyeings imparted by the use of ultrasound during dyeing.     

The preparation of ultra-high modulus polypropylene films and fibres

Following the discovery that linear polyethylene can be drawn to very high draw ratios to produce oriented fibres and films with ultra-high initial moduli, a similar study has been undertaken for polypropylene. In particular, the modulus/draw ratio relationship has been obtained for a range of polymers of different molecular weight and molecular weight distribution. The effects of thermal history and draw temperature were studied, and it was shown that under optimum conditions material with an initial modulus at room temperature of 1.9 × 10¹⁰ Nm^?2 (205 gdtex, 3 × 10⁶ psi) can be obtained. This value is at least 50 percent greater than those previously recorded for drawn fibres and about one half of the theoretical modulus.     

Dyeing of N-modified viscose rayon fibres with reactive dyes

Modified viscose rayon fibres were produced by incorporation of different doses of a polydiallyldimethylammonium chloride based additive in the viscose dope prior to spinning. On dyeing the modified fibres with different reactive dyes, excellent dye exhaustion and total dye fixation above 90% were obtained without the use of electrolyte and with low salt concentration. Exhaustion and total dye fixation showed an exponential relationship. The wash fastness properties of the dyed fibres were excellent and the light fastness showed a slight drop in the modified fibres. The presence of the amino groups along with low density and crystallinity of the modified fibres may be responsible for the enhanced dyeability.     

Halochromism of acrylic fibres dyed with some disperse dyes

Anomalous dyeing behaviour has been found when regular acrylic fibre treated in hydrochloric acid, in which the sulphonic acid group was present entirely in the acid form, was dyed in neutral condition with azo and anthraquinone disperse dyes. In the very early stages of dyeing there was an abnormally high degree of dye exhaustion, with bathochromic (azo) or hypsochromic (anthraquinone) colour changes on the fibre. These phenomena gradually disappeared after prolonged dyeing, with normal adsorption equilibria and colours eventually being obtained. The results were explained on the basis of protonation by the sulphonic acid groups of treated fibre which occurs at the azo nitrogen or the amino nitrogens of the substituents in the 1 — or 1,4-positions of anthraquinone. The normal adsorption equilibria after prolonged dyeing was attributed to hydrolysis of the cyano side group to form carboxylic acid. This produces ammonia to liberate neutral dye from the protonated dye cation adsorbed electrostatically by the sulphonic acid anion of the treated fibre.     

Dyeing properties of oxygen low-temperature plasma-treated wool and nylon 6 fibres with acid and basic dyes

Wool and nylon 6 fibres treated with oxygen low-temperature plasma were dyed with acid and basic dyes. Despite the increase of electronegativity of the fibre surface caused by the plasma treatment, the rate of dyeing of wool was increased with both dyes, while that of nylon 6 was decreased with the acid dye and increased with the basic dye.     

Diffusion of dyes in natural fibres

This review provides a summary of research on the penetration of dyes into natural fibres. Emphasis is placed on the relationship between diffusion and the structural morphology of the fibres. The types of commonly dyed natural fibres, the methods of measurement of diffusion and the data that have been collected by the use of each method are reviewed. The applicability of general theories of dyeing to natural fibres is also examined. Recent developments that have led to the direct observation of penetration pathways in wool fibres are described, together with the insights obtained into diffusion phenomena. Areas for future work are briefly indicated.     

The dyeing of poly(lactic acid) fibres with disperse dyes using ultrasound: Part 1 - Initial studies

Six disperse dyes were applied at 0.5%, 1% and 2% omf depths of shade to poly(lactic acid) fabric at 30-80 °C for 20, 50 and 90 min in both the presence and absence of ultrasound. Whilst ultrasound enhanced the colour strength obtained for three of the six disperse dyes used at temperatures upto 70 °C, ultrasound did not always result in enhanced colour strength being achieved in the case of the three other dyes. The observed intensification of colour strength was attributed to dye disaggregation. Dyeing at 80 °C in the presence of ultrasound resulted in pale, dull dyeings of reduced colour strength, which was attributed to breakdown of the dye dispersions at this particular temperature.