Kyunghee Son

Dyeing Properties and Color of Silk Fabrics Dyed with Safflower Yellow Dye

The objective of this study is to investigate the dyeing properties of safflower yellow dye on silk for the standardization of dyeing process and color reproducibility. Yellow colorants were water-extracted from safflower petals, concentrated, and freeze-dried to obtain colorants powder. The effects of dye concentration, dyeing temperature, and pH of dye bath were studied in terms of dye uptake and shade. Fastness to dry cleaning and light was evaluated. Dye uptake increased with raising temperature and brighter and more vivid yellow shade was obtained when dyed at . As colorants concentration increased, dye uptake increased progressively and the shade got darker and deeper. Maximum color strength was obtained at pH 3.5. It was speculated that the adsorption of colorants seemed to occur mainly by hydrogen bonding and physical force at pH 5.5 and by ionic bonding as well as hydrogen bonding below isoelectric point(pH 3.8-4.0). The results of reproducibility test showed acceptable color difference in the range of . Washing fastness was fairly good as 4/5 rating, while light fastness was 2/3 rating.

Tencel Dyeing by Natural Indigo Prepared from Dyer`s Knotweed

Natural indigo dye in powder form was prepared by modifying traditional Niram method, using instead of baked oyster powder for precipitating indigo dye. The prepared dye was applied to dyeing Tencel fabrics to investigate the effect of experimental conditions for the optimization of dyeing process. The indigo dye powder contained 15.2%(w/w) of indigo content and 0.757%(w/w) of indirubin content on the basis of HPLC analysis. Maximum dye uptake was obtained at for 20min. Almost saturated dye uptake was obtained at 2g/L of sodium hydrosulfite concentration up to 4g/L of indigo dye and then slowly increased for further increase of sodium hydrosulfite. Whereas at higher indigo dye concentration(8g/L) more than 3g/L of reducing agent concentration was required for obtaining the maximum dye uptake. At the same indigo dye and reducing agent concentration, K/S value of the sample dyed without sodium hydroxide(pH 5.75) was 15.19, much higher than one dyed in alkaline condition(K/S 5.76). There was no difference in colorfastness ratings among samples with different color strength. However, more fading was occurred for the sample with low color strength.

Optimization of Cellulose Dyeing with Natural Indigo: Ramie dyeing by One-step Reduction/dyeing Process

One-step reduction/dyeing method was applied for ramie dyeing with natural indigo powder. The effect of reduction/dyeing conditions including the pH of bath, dye temperature and time, and concentration of indigo powder and reduction agent on dye uptake and color properties were investigated. Regardless of addition of alkali, the dyed fabrics appeared in the PB Munsell color range(: 660 nm) and the dye uptake was much higher with no addition of sodium hydroxide. Dyeing was carried out through the use of only sodium hydrosulfite in the bath. The maximum dye uptake was obtained at 60 for 30min. Saturated dye uptake was obtained at 2 g/L of sodium hydrosulfite concentration up to 2 g/ L of indigo powder. Whereas, at higher indigo powder concentration (4 g/L), more than 3 g/L of reducing agent concentration was required for obtaining the saturated dye uptake. Color reproducibility was reliable with color difference in the range of 0.03~0.16. Regardless of color strength, fastness to rubbing was acceptable with a 3/4~4/5. Fastness to washing, dry cleaning, and light of samples with low color strength were poor. Whereas, fastness to washing, dry cleaning, and light of samples with high color strength were very good.

Dyeing Properties and Storage Stability of Leaf Powder Prepared from Dyer`s Knotweed (I) - by Freeze Drying method -

Abstract ― The objective of this study is to investigate the efficacy of l eaf powder colorants as substitutes for traditional fresh juice extract dyeing. Three kinds of leaf powder colorants were prepared by freeze drying method with or without deep freezing as pre-treatment: one powder colorant from fresh leaf juice wit h deep freezing; two kinds of powder colorant from fresh leaves with and without deep freezing. Their dyeing properties and sto rage stabilities were studied and compared with the traditional fresh juice extract dyeing. The presence of indigo in the powde r colorants was confirmed by UV/Visible absorption spectra. The y showed absorption peak at 602nm which was same with indigo abso rption peak. Dyeing was done at low temperature around 6 ℃. All three powder colorants produced B colors on silk fabrics, s howing similar color to the one dyed traditionally with fresh j uice extract. The powder colorants from leaves gave higher color str ength than the powder from leaf juice. The powder colorant prepared from leaves with deep freezing was the most stable for long term storage as its color and color strength were not changed after 360 days. So, this was used for further dyeing to study the effects of concentration and repeat dyeing on color strength and colorfastness. Fastnesses to dry cleaning and rubb ing were fairly good above 4 rating. Further study is needed to improve light fastness. It was concluded that the leaf powder c olorant with deep freezing could be used as a substitute for traditional juice extract dyeing at all seasons.

Dyeing Properties and Storage Stability of Leaf Powder Prepared from Dyer`s Knotweed(II) - by Hot Air and Room Temperature Drying Methods -

The objective of this study is to investigate the efficacy of leaf powder colorants as substitutes for traditional indigo dyeing. Leaf powder colorants were prepared by hot air() and room temperanrre() drying methods from fresh leaves. The presence of indigo in the leaf powder colorants was confirmed by UV/Visible absorption spectra. All the powder colorants showed broad absorption at 602 nm as same as synthetic indigo. Dyeing was done by reduction method with sodium hydrosulfite and sodium hydroxide. Leaf powder colorants produced blue color on silk fabrics, showing similar color to the one dyed traditionally with fresh juice extract. The powder colorants prepared at room temperature drying were more stable for long term storage than that prepared by hot air drying. Thus, the powder colorants prepared by room temperature drying was reduced and dyed in one-step process without sodium hydroxide in the dyebath for further investigate dyeing properties. K/S value of the fabric dyed without sodium hydroxide was much higher than one dyed with sodium hydroxide. Regardless of the addition of sodium hydroxide, rubbing fastness was fairly good showing above 4 rating. Fastness to dry cleaning and light of the fabrics dyed without sodium hydroxide were mote higher than that dyed in alkaline condition.

Indigo dyeing onto ramie fabric via microbial reduction: Reducing power evaluation of some bacterial strains isolated from fermented indigo vat

This research is to examine the reducing power of bacterial single strain and the mixture of strains. Four strains of Dietzia sp. KDB1 (KC433534), Nesterenkonia sp. KDB2 (KC433535), Nesterenkonia sp. KDB3 (KC433536), and Nesterenkonia sp. KDB4 (KC433537) separated from the fermented indigo vat were cultivated in aerobic condition. Natural indigo of the niram powder obtained from the water extract of Polygonum tinctorium and synthetic indigo purchased was used after sterilization. Natural and synthetic indigo samples were reduced with the strains in an incubator. Oxidation/reduction potential and pH of the mixture of indigo and strain(s) solutions were measured at the same intervals of elapsed time. Dyeing test was applied to evaluate the reduction power of bacterial strains isolated. Ramie fabric was used for the indigo dyeing and its color strength was determined from the reflectance at 660 nm and expressed as K/S values by using a spectroscope. CIELAB coordinates were measured with the same spectroscope and H V/C values were obtained by using the conversion program. All the strains showed reducing power onto natural and synthetic indigo samples. With the elapsed time, dye-uptake was increased up to maximum dye-uptake, and then decreased. The potential was dropped rapidly around −500 mV and then changed very slightly maintaining lower than −400 mV. The pH measured was decreased with the elapsed time. All the hue values obtained were of bluish purple (PB) shade. On the reducing power represented as dye-uptake, KDB1 strain was the highest among the strains selected for natural indigo and KDB3 strain for synthetic indigo. KDB2 showed the lowest for both of natural and synthetic indigo. Mixture of strains shortened the start time of reduction and that of maximum dye-uptake than any single strain.

Effect of Extraction Solvents on Color of the Dyed Fabrics with Safflower Red Colorants

Safflower red colorants extracted by two solvents including the traditional ash solution and solution was used for dyeing cotton, ramie, viscose rayon, silk, wool, and nylon fabrics. The effects of extraction solvents on the reflectance, K/S value, and color properties of the dyed fabrics were investigated. Wash/dry cleaning and light colorfastness were evaluated. Reflectance curves of cotton, ramie, viscose rayon, and silk fabrics dyed with red colorants extracted by solution were similar, showing the maximum absorption at 520nm, to that of the dyed fabrics with red colorants extracted by ash solution. The reflectance curves of wool and nylon fabrics were different, showing the maximum absorption at 400nm. K/S values of dyed fabrics with red colorants extracted by solution were higher than that by ash solution with the exception of nylon. , and of the dyed fabrics with red colorants extracted by solution were higher than that by ash solution except for of nylon and of viscose rayon. Color difference() of the dyed fabrics between ash solution and solution increased in the order named as cotton, silk, ramie, viscose rayon, wool, and nylon. Regardless of extraction solvents, safflower red colorants produced RP color on cotton, ramie, and nylon, R color on viscose rayon and silk, and YR color on wool. Wash/dry cleaning fastness of the dyed fabrics was high above 3/4 rating but light fastness was very poor. It is considered that the use of solution instead of the traditional ash solution would be more effective in terms of color reproducibility and extraction process.

Development of Eco-friendly Reduction Process for Indigo Dyeing : Using Hansenula misumaiensis Strain

The aim of this study is to develop an eco-friendly reduction process of indigo as an alternative choice. Hansenula misumaiensis was used and their reducing activity toward synthetic indigo as well as natural indigo was estimated by dyeing test in terms of indigo dye uptake. The changes in K/S value and pH were monitored on the time-based measurements. Also, reduction duration was evaluated. On the basis of the results described in this study, it was confirmed that Hansenula misumaiensis reduced indigo. Reducing power of Hansenula misumaiensis reached to maximum in two days. It can be possible to develop eco-friendly process of indigo reduction using Hansenula misumaiensis by the optimization of strain culture conditions and the optimization of reduction conditions.

Evaluation of aroma functionality imparted on natural indigo-dyed cotton fabrics

Long-term efficacy of aroma microcapsules on natural indigo-dyed cotton fabric was evaluated by objective and subjective tests. The fixation of aroma microcapsules was carried out by pad-dry-cure process on dyed cotton fabric. Mercerized cotton fabric was dyed with natural indigo obtained from Polygonum tintorium (via the modified Niram method) and subsequently padded with melamine-formaldehyde microcapsules containing aroma essential oil (natural source of a Chinese arborvitae 20-25 %). Softener was applied in the same (one-step) or sequential (two-step) padding bath. We confirmed that microcapsules were fixed on cotton fibers by SEM analysis. The addition of softener was not much effective for the fabric performances on softness or air permeability. All the colorfastness ratings were above 4/5 and the color difference was within the acceptable range of 1.62-2.08. The efficacy of fabric samples stored for 2 years was evaluated using the GC/MS-headspace technique and the samples stored for 0.5, 1.5, and 2.5 years were also evaluated in terms of aroma release by the human perception test. Bornyl acetate was confirmed as the main component of essential oil, which was continuously released by the microcapsule-treated fabric (D/MC) during storage for more than 2 years. In durability and human perception tests, the microcapsules on the cotton fabric were stable to laundering, rubbing, ironing, and light.

자연발효 과정에서 인디고에 환원력을 지닌 미생물 커뮤니티 분석과 농화배양

Indigo is utilized in various industries including textile dyeing, cosmetics, printing and medicinal products and its reduced form, leuco-indigo, is mainly used in these process. Chemical reducing agent (sodium dithionite, sodium sulfide, etc.) is preferred to use for the formation of leucoindigo in industry. In traditional indigo fermentation process, microorganisms can participate in the reduction of indigo and thus it has been known to reduce environmental pollution and noxious byproducts. However, in fermentation method using microorganisms it is difficult to standardize large scale production process due to low yield and reproducibility. In this study, we attempted to develop the indigo reduction process using microbial flora which was isolated from naturally fermented indigo vat or deduced by metagenomic approach. From the results of library analyses of PCR-amplified 16S rRNA genes from the traditional indigo fermentation vat sample (metagenome), it was confirmed that Alkalibacteriums (71%) was distinctly dominant in population. Some strains were identified after confirming that they become pure culture in nutrient media modified slightly. Four strains were separated in this process and each strain showed obvious reducing ability toward indigo in dyeing test. It is expected that the analyzed results will provide important data for standardizing the natural fermentation of indigo and investigating the mechanism of indigo reduction.