Aqueous Dyeing Research Articles

Adsorption behavior of direct dye on cotton in non-aqueous media

Solubilization and adsorption behavior of direct dye on cotton in Aerosol-OT (AOT) revere micellar system has been investigated. Cotton fabrics could be dyed in deep shade with direct dye from reverse micellar system without adding auxiliaries. Exhaustion of dye was almost perfect and was very superior to that in aqueous system. High exhaustion of the dye in reverse micellar system was attributed to the very low bath-ratio (water–fabric ratio) compared to the conventional aqueous dyeing process. It has become obvious that adsorption of direct dye on cotton in reverse micellar system is similar to that in aqueous system and follows a Freuindrich manner.

A microscopical study of the pathway for diffusion of rhodamine B and octadecylrhodamine B into wool fibres*

The pathways for the diffusion of the basic dyes rhodamine B and octadecylrhodamine B into wool under aqueous and non–aqueous dyeing conditions have been investigated. The distribution of each dye within the fibre at various stages of the dyeing process was monitored by fluorescence microscopy. By judicious choice of solvent system and treatment time, the dyes could be directed into different histological components of the fibre. Intercellular diffusion, involving passage of the dye through the cell membrane complex between the cortical cells, was generally the preferred route for penetration of the fibre. The distribution patterns of the two dyes differed markedly and were strongly dependent upon the solvent composition. Whilst selective staining of the cell membrane complex occurred in an anhydrous solvent system, preferential staining of that region of the cell membrane complex associated with the orthocortex resulted when the dyes were applied from aqueous alcohol systems.

Load Elongation Properties of Filaments in a Multifilament Yarn

This paper describes the technique of finding the distribution of load-at-break and elongation-to-break of filaments in a multifilament yarn from the breaking steps in a load-elongation diagram. There is a correlation between the distribution data and the performance of undrawn nylon 6 yarn on the draw-twisting machine. The dis tribution in the drawn yarn is correlated with that of the undrawn yarn. The effect of spinning speed of the filament yarn on the distribution is brought out using low- speed spun nylon 6 yarn and MOY and POY polyester. The effect of the hot water relaxation process and aqueous dyeing process on the distribution is also studied.

Dye Resist Effect in Polyester Homopolymer During Aqueous Dyeing

Experimental evidence shows that during aqueous dyeing of polyester homopolymer, a dye-resist effect in the polymer is generated. Possibly it is due to the effect of aqueous thermal energy and is eliminated with the use of a carrier in the dyebath.

EFFECT OF NONIONIC SURFACTANT ON POLYESTER PRINTING BY SUPER HEAT STEAMING

It is known that nonionic surfactant is an effective dyeing accelerator in polyester printing by super heat steaming. In this paper, 4 mol ethylene oxide addition of orthophenyl phenol (OPP-(EO)4) was used as a model compound of dyeing accelerator, and the dyeing behavior was compared with those of OPP and urea. OPP-(EO)4 was more effective than urea to accelerate the polyester printing by super heat steaming, however, it was quite ineffective in aqueous dyeing. An addition of OPP-(EO)4 in dyeing solution was found to decrease the dyeing properties, because the partition coeffi-cient decreased by the increase of the solubility of dye.Furthermore, change of the fine structure of polyester fiber treated with OPP-(EO)4 and OPP was investigated by X-ray diffractometry and dynamic viscoelastic measurement. The fine structure of the fiber was changed markedly by OPP treatment. On the contrary, the change was scarcely observed by OPP-(EO)4.From these results, the effect of OPP-(EO)4 on the dyeing improvement in polyester printing can be considered to increase the dye solubilization and the dye transfer in printing paste during super heat steaming.

Carrier Dyeing of Polyester Fibre Part III – The Role of Water in Solvent Dyeing

The role of water as an auxiliary in solvent dyeing of polyester fibre has been studied. The addition of water results in a lowering of the glass transition temperature, an increase in the diffusion coefficient and reductions in the energy of activation of diffusion and the entropy of activation of diffusion. The increase in the diffusion coefficient is smaller at higher temperatures and varies from dye to dye, being related to the energy of activation of diffusion. These effects are similar to those reported previously for carriers in the aqueous dyeing of polyester fibre and demonstrate that the role of water in solvent dyeing is similar to that of a carrier in aqueous dyeing.

Azide Reactive Dyes

Reactive dyes containing a sulphonylazide group can undergo fixation on nylon substrates by two different mechanisms. Under aqueous dyeing conditions, at or below 120d̀ C, the free amino end‐groups of the polymer attack the sulphonylazide group with displacement of azide ion, and results in attachment of the dye to the substrate by a sulphonamide linkage. In contrast, if the dyed substrate is subjected to dry heat fixation at 170d̀ C, the azide group decomposes to a sulphonylnitrene species which undergoes insertion into C‐H bonds of the polymer. The dye is again attached by a sulphonamide bridge, but in this case the amount of dye that can be fixed is independent of the amino end‐group content of the polymer.

Alternatives to Water in Textile Processing

Attempts have been made to correlate the use of organic solvents as alternatives to water in textile processing with the ‘solubility parameter’ concept. Chlorinated hydrocarbons prove suitable for scouring and some finishing operations since their solubility parameters are ideal for such operations. In dyeing, however, the solubility parameter of polyester fibres, dyes and perchloroethylene are very similar, resulting in poor exhaustion of conventional disperse dyes. New solvent dyeing systems and new dyes, with high partition coefficients in polyester fibres, must be developed for solvent dyeing to become of practical consideration. Other solvents have been examined for solvent assisted dyeing. It has been shown that when benzyl alcohol and 2‐phenoxy ethanol are used in dyebaths at concentrations at which these solvents are not completely in solution, both the rate of dyeing and penetration of dye into the fibre can be markedly increased in comparison to normal aqueous dyeing with polyester, nylon and acrylic fibres.

Studies of Solvent Dyeing

Behavior of non-ionic (disperse) dyes when dying nylon 6, polyethylene terephthalate and triacetate fibers in organic solvents has been studied, and following results are obtained.(1) The absorption isotherm can be expressed in a formula according to Nernst's partition law.(2) The partition coefficient, the affinity of dyeing and the heat of dyeing in organic solvents are much smaller than those in an aqueous dyeing system.(3) The diffusion coefficients differ very much by the combination of fibers and solvents. The rate of diffusion increases largely by increasing the degrees of fiber swelling by solvents.(4) The swelling of fibers is correlated with the solubility parameter of the solvents. The degree of maximum swelling takes place in solvents the solubility parameter of which is nearly equal to that of fibers.

APPLICATION OF WILLIAMS-LANDEL-FERRY EQUATION TO THE DIFFUSION OF DISPERSE DYES IN POLYESTER

1. The applicability of equation (1), obtained by the author, to the diffusion of many disperse dyes in the aqueous dyeing of polyester rolled film was investigated using the data published in literature.where aT, D and T are shift factors, diffusion coefficient and absolute temperature, respectively. The subscript s indicates the values at a refference temperature. The square of the diffusion layer, l, was used in place of the diffusion coefficient. It was found that eq. (1) is applicable to the diffusion of many dyes practically used, and that log ls2 decreases with the increase in the molecular size of the dyes.2. Eq. (1) was also found to be applicable to the dyeing of polyester in tetrachloroethylene (TCE) as it was in aqueous dyeing. The increase in the diffusion coefficient and the smaller dependence on temperature in the TCE dyeing than in the aqueous dyeing were explained by the lowering of Ts due to the lowering of the glass transition point of the polyester in TCE.

DYEING OF POLYESTER WITH DISPERSE DYES FROM PERCHLOROETHYLENE

The purpose of this work is to obtain the information on the dyeing behavior of polyester with disperse dyes from a perchloroethylene solution. The absorption isotherms for C. I. Disperse Red 88, azo-type, (I) and C. I. Disperse Red 60, anthraquinone-type, (II) were determined at 5°C intervals from 100° to 120°C, using polyester film. The absorption isotherms obtained were linear for all dyes. From the absorption isotherms, the partition coefficient and the heat of dyeing were calculated. The partition coefficient ranged from 8-14 for dye (I) to 0.6-0.7 for dye (II). These values are much smaller than for aqueous dyeing at the same temperature. The heats of dyeing for dye (I) and dye (II) were -7 and -2 kcal, respectively. These values are larger ca. 4 kcal than for aqueous dyeing. The diffusion coefficient in the substrate for dye (I) and dye (II) were determined at various temperatures by means of film roll method. The polyester film used was pretreated in a blank dyebath at 120°C. The diffusion coefficients thus obtained did not show any dependency on the concentration of the absorped dye in the film. The diffusion coefficient ranged from 2.56×10-9-2.74×10-8 for dye (I) to 1.87×10-8-5.91×10-8 cm2/min for dye (II). These diffusion coefficient are much larger than for aqueous dyeing. From the temperature dependence of diffusion coefficient, the activation energies for diffusion were calculated for dye (I) and dye (II). They were 32 and 17 kcal, respectively, which are smaller than for aqueous dyeing. From the results obtained in this work, a schematic drawing for swollen polyester in perchloroethylene was obtained.

The Dyeing of Cellulose Acetate with Non‐ionic Dyes IIIndashDyeing from the Vapour Phase

A study has been made of the absorption from the vapour phase, by secondary cellulose acetate, of five model dyes. These are p‐nitroaniline, NN‐dimethyl‐p‐nitroaniline, azobenzene, p‐aminoazobenzene, and NN′‐dimethyl‐p‐aminoazobenzene. The amounts absorbed at equilibrium have been measured, and their dependence on the vapour pressure of the dyes and the temperature of the substrate has been established.The vapour pressures of the dyes have been measured over a range of temperatures, those of azobenzene by manometry and the remainder by Knudsen's effusion method. The results together with the absorption data yield absorption isotherms from which are derived the isosteric heats of absorption of the dyes on cellulose acetate. The values, in the above order, are as followsndash21.2,–21.4,–17.8,–22.0, a22.7 kcal. /mole.The vapour pressure data are also used to evaluate the heats of vaporisation or sublimation of the dyes. These heats are applied to aqueous dyeing data already published to derive the absolute heats of association of the dyes on cellulose acetate. The results are in substantial agreement with the heats of absorption of the vaporised dyes.A brief study has been made of the absorption by, nylon and Terylene of vaporised azobenzene. The results for nylon yield a value for the heat of absorption of–18.0 kcal./mole. The results for Terylene are insufficiently complete for quantitative treatment.