Dong Il Yoo

Natural Indigo Dyeing of Cotton Fabric - One-step reduction/dyeing process -

The objective of this study is to investigate the characteristics of natural indigo dyeing of cotton fabric. Reduction and dyeing were carried out by one-step process using an infrared dyeing machine at the liquor ratio of 1:100, and subsequently oxidation and washing in water were followed. Dye uptake was increased with the increase of indigo concentration. Over the full range of dyeing tests, the dyeing condition was optimized to 40℃ for 40min. For most of dye concentrations, the cotton fabrics showed mainly PB color. Maximum K/S value was shown at 4g/L of sodium hydrosulfite concentration and the color strength increased with the increase of dye concentration. Value(lightness) decreased with the increase of dye uptake irrespective of mercerization or reduction method, while the mercerized cotton showed two times higher dye uptake than the untreated cotton. Whereas hue of the untreated cotton showed large decrease of P character(5.6~3.5 PB) with the increase of dye uptake, that of the mercerized cotton increased P character(4.7~5.5 PB). Irrespective of mercerization, value and chroma decreased with the increased of dye uptake. In addition, the untreated showed lower chroma than the mercerized cotton. In the case of traditional reduction, hue of the untreated cotton was changed very little with the increase of dye uptake. For hydrosulfite reduction, P character decreased with the increase of dye uptake. The difference of hue value was small with the change of reduction method(hydrosulfite reduction or traditional fermentation). Color character was not influenced by the changed maximum absorption wavelength. Washing fastness showed 4~4/5 shade change rating without any staining. And dry rubbing fastness was good at low color strength. The bacterial reduction ratios of dyed cotton fabric were also increased.

Utilization of Metasequoia(Metasequoia glyptostroboides) Cone as a New Natural Dye Resource(2): Dyeing Properties and Antimicrobial Functionality of Silk Fiber

The aim of this study was to investigate the possibility utilizing Metasequoia(Metasequoia glyptostroboides) cone as a new natural dye resource. In previous study, dyeing onto cotton fiber was carried out and Metasequoia cone colorant showed low affinity to cotton fiber and maximum dye uptake was obtained at pH 3.5 showing YR Munsell color. For further evaluation of its efficacy as a new natural dye resource, effects of dyeing conditions and mordanting on dye uptake, color change, and colorfastness were investigated for silk fiber. Metasequoia cone colorant showed good affinity toward silk fiber showing YR Munsell color and maximum dye uptake was shown at pH 3.5. Post-mordanting with Cu and Fe improved dye uptake, especially Fe() mordant was effective as much as 2 times higher dye uptake comparing with un-mordanted sample. The color of dyed fabrics with mordanting showed YR Munsell color. Fe mordanted fabrics appeared dark gray~black color. Colorfastness to washing was relatively good, whereas lightfastness of the dyed fabrics showed grade 2. It was confirmed that Metasequoia cone colorant can be used as a new dye resource for silk fiber getting brownish yellow to dark gray/black color depending on mordant type. In addition, it showed antimicrobial functionality.

Process Balance of Natural Indigo Production based on Traditional Niram Method

In this work, the natural indigo production process from Polygonum tinctorium was balanced based on the traditional Niram method in Korea. A standard procedure was determined considering the conditions of indican extraction from plant material, the amount of alkali for precipitation, storage of extract, etc. The effect of experimental conditions on the yield of crude dye was investigated. The contents of indigo and indirubin of the crude dyes were analyzed by HPLC. Increase of the amount of crude dye was observed within 1-2.5 days of extraction time. Longer extraction beyond 2.5 days resulted in a slight decrease in the amount of crude dye. There was no consistency in terms of indigo content depending on extraction pH. We found that the storage of extract or harvested plants affected adversely to dye yield and dye quality. Based on the lab scale extraction, large scale extraction was performed for 2-2.5 days in water and 2.0-2.5 g/L of Ca(OH)2 was applied for precipitation of indigo dye. We obtained natural indigo dye containing about 15% of pure indigo in scale?up production using whole plant except root.

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.

Utilization of Metasequoia(Metasequoia glyptostroboides) Cone as a New Natural Dye Resource(1): Dyeing of Cotton Fiber

Abstract : The aim of this study was to investigate the possibility utilizing Metasequoia( Metasequoia glyptostroboides ) cone as a new natural dye resource. Dyeing onto cotton fiber was carried out to study the effect of dyeing conditions and mordanting effect on dye uptake, color change, and colorfastness. FT-IR analysis supported that hydrolyzable tannins were contained in the extracted colorant. Metasequoia cone colorant showed low affinity to cotton fiber and maximum dye uptake was obtained at pH 3.5 showing YR Munsell color. Mordanting improved dye uptake regardless of mordant type, especially Fe(C 5 H 10 FeO 6 ) mordant was effective as much as 2 times higher dye uptake comparing with un-mordanted sample. The color of dyed fabric with mordanting showed YR Munsell color except of the Fe(FeSO 4 ·7H 2 O) mordanted sample showing Y Munsell color. Colorfastness to rubbing and washing was relatively good, whereas lightfastness of the dyed fabrics was above grade 3/4 except that the dyed samples with Fe mordanting showed grade 2. It is necessary to apply Metasequoia cone colorant onto other fibers, especially protein fibers, for evaluating its efficacy as a new natural dye resource.

Utilization of fruit by-products for organic reducing agent in indigo dyeing

This study aimed to investigate the efficacy of banana peel extract as a possible substitute for the environmentally unfavorable sodium dithionite in cellulosic fiber dyeing with indigo. Antioxidant activity and total sugar content of the banana peel extract were measured. Composition of the extract was investigated by GC/MS analysis. Its reducing power for synthetic indigo was evaluated by reduction potential measurements and dyeing tests. It was shown that the studied extract could be applied successfully in the reduction of indigo in spite of their lower reducing power when compared with that of sodium dithionite. In dyeing study, sodium dithionite showed its superiority in term of reducing power over the studied extract but the studied extract was superior stability of reduction to sodium dithionite. So, it can be concluded that banana peel extract could be a biodegradable and sustainable alternative to sodium dithionite as a reducing agent in indigo dyeing processes.

Evaluation of hair-dyeing by using Rubus coreanus Miquel sludge

Hydro-extraction, enrichment by evaporation, and freeze drying processes were sequentially carried out to extract the colorants from the Rubus coreanus Miquel sludge which was supplied as the waste of the traditional wine process. The dyeing on to human hair was performed at some pH values by using the commercial condition; 0.4 g of human hair, 100 % (on the weight of hair) of the powder of colorants, liquor ratio 1:5, 40 °C and 30 min. The extract was evaluated by UV-vis spectroscopy, antioxidant property (DPPH radical scavenging activity) and antimicrobial activity measurements. Color of the extract in aqueous solution was red at pH 2, violet at intermediate pH condition, and brown at pH 9. Color properties and colorfastness to light and washing were also analyzed for the hair samples dyed with the extract. With the variation of pH, the color of dyed hair was observed mostly BG-RP at pH 2-5 and then changed to YR-GY at pH>6. For the dyed hair samples, light colorfastness was relatively good; the rating 3 was maintained up to 40 hrs. The rating of wash colorfastness was remained 3 for 25 cycles. Results of color analysis and fastness tests confirmed that the colorants from the Rubus coreanus Miquel were successfully applied to hair-dyeing.

Storage Stability and Color Reproducibility of Yellow and Red Dyes Extracted from Carthamus tinctorius L.

The stability of yellow and red dyes prepared from safflower (Carthamus tinctorius L.) in aqueous solution and in solid state was investigated. External factors such as light irradiation and temperature on the stability were examined during storage. Changes in absorbance of dye solutions and the color changes of fabrics dyed after long time storage were measured. Also, color reproducibility during storage was investigated by dyeing test on various fabrics. Red colorant in aqueous solution was very unstable to light, resulting that about 40% of absorbance were lost in 12hrs. The absorbance of yellow dye solutions was not decreased within 84hrs. In aqueous medium, yellow dye was much more stable than carthamin. Both dyes are relatively stable for long storage when they are stored in solid state compared to when in aqueous solution. Color changes are marginal in both dyes.

Pretreatment Process for Production of the Gromwell Colorants Powder

In this work, colorants extraction process from gromwell was studied for making powder form of colorants by solving the high viscosity problem of gromwell extracts. In order to do that, sugar extracted together with colorants must be pre-extracted. For sugar decomposition, gromwell roots were pretreated with various enzyme solutions. The total sugar content of pre-extract with enzyme solution was measured. Accordingly, the effects of enzyme type and pretreatment condition on sugar decomposition were investigated to find appropriate enzyme(amylase, hemicellulase, pectinase) and enzyme activity (100~1000unit), pre-extracted time(3~24hr). Color characteristics and dye uptake of dyed fabrics were evaluated. Gromwell colorants were assessed for their potential antimicrobial activities, which possibly expand their end use as functional pigments. The efficiency of removing sugar was increased in the order of hemicellulase, pectinase, amylase, H2O. Gromwell colorants powder yield was in the range of 4.4% to 9.8% depending on pretreatment enzyme. Gromwell colorants produced RP color on the silk and wool fabrics with good dye uptake. Antimicrobial activity of gromwell colorants will greatly increase its potentiality for applying as functional natural colorants in the future.