Research On Foaming Properties And Foam Dyeing Process Of Reactive Dye

The traditional dyeing and finishing industry is generally associated with pollution and high consumption in energy and water. The foam dyeing and finishing technique that can save energy and water is more ecological, which has gained much interest in recent years. However, the permeability of dyes and chemicals, level-dyeing property during foam dyeing and finishing need to be improved. This paper takes foam dyeing of KE-type reactive dyes as the research content. Foam properties and influence factors on the foam dyeing and finishing are researched. Color fixation rate and the K/S value are analyzed and used to evaluate dyeing effects of practical foam dyeing.Firstly, mechanical stirring method was used to make frothers foaming. Different ion types of frothers were used to produce foam and the foam properties were compared. The effects of stabilizers, temperature, concentrations of reactive dyes, inorganic salts, sodium carbonate and urea on foaming properties and foam stability were studied.As an anionic surfactant, sodium dodecyl sulfate had the best foam properties among all the tested frothers, so it was used as the frother in this study. The effects of concentration of sodium dodecyl sulfate on foam properties were studied and it was found that the optimum concentration of sodium dodecyl sulfate was 2g/L. When stabilizers were added in the foam system independently, foam stability increased with the rising of stabilizers concentration. When combinations of each two stabilizers were added in the foaming solution, dodecanol(1.5g/L) and guar gum(2g/L) produced the most stable foam with the half-life of the foam of 6361s(106min) among all combinations of two stabilizers. Temperature had a big influence on the foam properties. Foam stability decreased with the temperature rising. When Reactive Brilliant Red KE-3B was added in the foam system, the half-life of the foam increased slightly at first and then declined. In addition, when inorganic salt, sodium carbonate and urea were added separately in the foaming solution (SDS 2g/L, dodecanol 1.2g/L, guar gum 1.6g/L and the dye 5g/L), it was found that inorganic salt and sodium carbonate had little influence on the foaming properties, but they both had a great influence on foam stability, and the influence of inorganic salt was greater than that of sodium carbonate. When concentration of NaCl reached 1g/L, the half-life of the foam dropped to 800s. When concentration of sodium carbonate reached 4g/L, the half-life dropped to 800s and started to maintain. Urea had little influence on the foaming properties, but it influenced the foam stability to some extent, when concentration of urea was 60g/L, the half-life dropped to 1200s and started to maintain.In the second part, that the foam generator and foam dyeing machine were used to dye the woven cotton fabrics was studied. The color fixation rates of fabrics were compared between the foam dyeing and traditional pad dyeing processes of the reactive dyes. It was found that the color fixation rate of foam dyeing fabric was not lower than that of traditional pad dyeing no matter it was fixed by steaming or curing. While using curing as fixation method, color fixation rate of foam dyeing fabric was higher than that of pad dyeing fabric. Color fixation rates of steaming fabric in both dyeing methods were higher than that of curing. So steaming was used as the fixation method and it was found the color fixation rate of fabric was the highest when steaming 2 min under 140℃, which was the shortest processing time as a high efficiency. Urea could improve color fixation rate of fabric for about 5%, but nitrogen concentration of waste water and the cost were also increased, so no urea was added. Stabilizers reduced the color fixation rate of fabric but increased cost. To ensure the K/S value, the optimum concentrations of stabilizers were 0.3g/L of dodecanol and 0.4g/L of guar gum. When the concentration of sodium carbonate reached 15g/L, the color fixation rate of fabric had a great improvement and didn’t increase notably after that. To ensure the K/S value, the optimum concentration of sodium carbonate was chosen as 15g/L. Blow ratio and up-take percentage were key to the dyeing effect. When blow ratio was 8, color fixation rate of fabric was the highest at 88.43%, when up-take percentage was 30%, both color fixation rate and K/S value of fabrics were considerable, so blow ratio of 8 and up-take percentage of 30% were chosen as the optimum foam dyeing conditions.In this study, foam dyeing could not only reduce consumption in chemicals, water and power but also reduce the processing time. It was an economic processing.