• Textile Coloration and Finishing
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• v.24 no.1
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• pp.18-26
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• 2012

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, $H_2O$. 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.

• Korean journal of food and cookery science
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• v.27 no.6
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• pp.643-651
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• 2011

The purpose of this study was to investigate the perceptions, intake levels and information needs of elementary school students on artificial food colorants in order to provide better understanding and proper dietary education to these students. From May to June 2010, a survey was conducted from 315 elementary school students at fifth and sixth grade level who were living in Seoul. The questionnaire was distributed by 14 elementary school teachers to their classroom students. The results showed that food safety was regarded as the most important factor in purchasing food items, and artificial food colorants were the most interested among various food additives. Although there was a lack of general knowledge and the students' estimated intake levels of artificial food colorants from processed foods were comparatively low, most (82.7%) believed that artificial food colorants were dangerous for health. The information they wanted to know most was the safety, necessity, and function of artificial food colorants, in order. Above results suggested the necessity of providing accurate information on artificial food colorants to elementary school students possibly by developing educational materials which can improve the perceptions on artificial food colorants and encourage a safe dietary life.

• Fashion & Textile Research Journal
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• v.10 no.2
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• pp.249-253
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• 2008

The purpose of this study was to investigate the properties changes of wool fabrics dyed with safflower red and yellow colorants under Ultraviolet(UV)-light. For this purpose, the wool fabrics dyed with safflower red and yellow colorants were compared with each other after uv-light exposure in terms of K/S value, color changes(${\Delta}E$), morphology, and strength retention. K/S value rapidly decreased with increasing exposure time, but K/S value of the samples dyed with safflower yellow colorants decreased less than that of the samples dyed with safflower red colorants. In color changes, as increasing exposure time, $L^*$ and $b^*$ increased, $a^*$ decreased, and thereby ${\Delta}E$ increased in the samples dyed with safflower red colorants, $L^*$ increased, $a^*$ and $b^*$ decreased, and so ${\Delta}E$ increased in the samples dyed with safflower yellow colorants, indicating fading away by uv-light and changes of hue, value and chroma value. But the color change of samples dyed with safflower yellow colorants was less than that of samples dyed with safflower red colorants. SEM pictures showed a severe degradation by uv exposure, regardless of colorants type. Tensile strength slowly decreased until 14 days, and rapidly decreased until 21 days and slowly decreased. Strength retention of the samples dyed with safflower yellow colorants was higher than that of the samples dyed with safflower red colorants.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.5
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• pp.557-564
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• 1998

Dyeing properties of silk fabric with black tea colorants were investigated in terms of dye uptakes at various dyeing conditions and the effect of mordants on color change and colorfastness. Black tea colorants showed high affinity to silk and produced brown color. Two types of adsorption isotherm were obtained; Langmuir and Freundlich equilibrium at 360 nm and 460 nm, respectively. Thus, it is considered that both of ionic and hydrogen bondings are involved in silk dyeing with black tea colorants. Dye uptake increased continuously as concentration of colorants increased. Brown color was not changed with mordant type except that Fe mordant produced dark brown color. Mordanting did not influence colorfastness of dyed silk significantly. Therefore, mordanting was not necessary in dyeing silk with black tea colorants.

• Textile Coloration and Finishing
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• v.34 no.2
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• pp.77-92
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• 2022

Natural colorants are regarded as substitutes for synthetic colorants in the fields of fiber dyeing, hair dyeing, cosmetic, and food industries. The use of natural colorants has been increased in view of global environment and sustainability. However, scientific approach to the production is required because the supply of natural colorants depends on the climate, soil, and cultivation methods. This brief review contains the advances in science and technology related to natural colorants including characterization, analysis, CIEL^*a^*b^* and Munsell color systems, and future prospects. For the characterization and the analysis of natural colorants, chromatography, some spectroscopic techniques (UV-Vis, FT-IR, NMR), mass spectrometry, and X-ray diffraction are generally used.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.4
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• pp.510-516
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• 1999

Dyeing properties of cotton fabrics with green tea colorants were studied by investigating the effects of dyeing conditions such as colorants concentration. pH dyeing temperature and time on dye uptakes effects of mordats on dye uptakes and color change and effects of cationizing agent on dye uptakes. And various colorfastnesses of dyed fabrics were evaluated for practical use. Green tea colorants showed low affinity to cotton and produced yellowish red color. Freundlich adsorption isotherm was obtained thus it is considered that hydrogen bondings are formed between colorants and cotton. Dye uptake was maximum at pH 5 and decreased as pH increased. Mordants especially Cu and Sn were effective for increasing dye uptake. Dye uptakes were improved remarkably by cationizing. Cationized cotton showed Langumuir adsorption isotherm indicating that ionic bondings were formed between colorants and cationized cotton. While mordanting did not affect lightfastness cationizing affected adversely. Colorfastness of cationized sample was generally inferior to that of mordanted samples.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.1
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• pp.124-132
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• 2002

Dyeing properties of silk fabric on gromwell roof colorants were studied for the effect of dyeing conditions, such as methanol ratio, colorants concentration, pH, temperature and time etc. on the dye uptake and effect of mordants and mordanting methods on color change and dye uptake. And various colorfastnesses of dyed fabrics were evaluated far practical use. Gromwell colorants showed high affinity to silk and its isotherm adsorption curve was Freundlich type close to Nernst type. Therefore, it is considered that hydrogen bonding and Van der Waals force were involved in the adsorption of cromwell colorants to silk fabric. Post-mordanting method gave higher K/S value than other methods, but it was not significantly different color values from unmordanted one. Gromwell colorants produced mainly R and RP color depending on mordants and mordanting method. Dyed fabrics showed high colorfastness irrespective of mordanting treatment. Light colorfastness was increased for repeatedly dyed and Fe mordanted dyed fabrics.

• Textile Coloration and Finishing
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• v.11 no.2
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• pp.38-45
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• 1999

Natural red colorants were extracted from Phytolacca americana Linne by using 50% ethanol solution at room temperature for 12 hours. The colorant components were partially purified as yellow and deep red colorants by thin layer chromatography. Natural red colorants were consisted of major water-soluble red colorant, having maximum absorbance at 538nm and alcohol-soluble yellow colorant, having maximum absorbance at 664nm. Concentration of red colorants were calibrated by the equation of dye(mg/ml) $A_{538nm}\times{1.284}$. Red colorants were changed to yellow at extreme alkali pH and repaired 55% color intensity by neutralization of pH and stabled below $55^\circ{C}$. Dyeability of red colorants against wool fabrics was mainly operated by red pigment having 538nm absorbance without big color differences. Below $55^\circ{C}$, color differences $(\Delta{E}^*_{ab})$ were not changed in spite of big difference of chroma$(c^*)$, having higher scores at higher temperature. The effect of mordants were not drastically changed parameters of color difference without copper ion. Citric acid was big changes of color difference$(\Delta{E}^*_{ab})$ in spite of similar chroma$(c^*)$ values. From these experimental results, red colorants from Phytolacca americana Linne is available for wool fabric dyeing.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.528-533
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• 2013

We focused on the development of red azo colorants with high thermal stability and good solubility for LCD color filter in this research. For the synthesis of hybrid azo colorants, we used the couplers of aniline, naphthol and benzoimidazol functional group. The synthesized hybrid azo colorants were charaterized by using NMR, UV/visible spectroscopy, FT-IR, EA and TGA. They represented the maximum absorption wavelengths which are longer than 500 nm in UV/visible spectrum. So they were confirmed to be suitable for red colorants of LCD color filter. Azo compound (1a, 1b) with aniline functional group had good solubility in organic solvents such as acetone, methanol, chloroform and PGMEA. Moreover azo compounds (1c, 1d and 1e) with naphthol and benzoimidazolone functional group gave excellent thermal stability higher than $250^{\circ}C$ in TGA thermograms.

• Fashion & Textile Research Journal
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• v.15 no.1
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• pp.138-146
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• 2013

Chemical compositions and biological functions of brown colorants extracted from pine bark(Pinus densiflora) have been studied. Dyeing test using multifiber fabrics with extracted colorants were preliminary carried out. Dyeing conditions and fastness tests of selected fabrics have been also studied. The brown colorants were produced 1.5% concentrations by solvent extraction from milled pine bark using methanol. The colorants were extracted with 80% methanol as best choice by a criteria of solid quantity and dyeability on fabrics. The chemical compositions were identified as mixtures of taxifolin epicatechin and procyanidin by LC/MS analysis. The brown colorants could be dyed not only natural fibers such as cotton, silk and wool but also synthetic fiber as nylon and semi-synthetic fiber as viscose rayon. Maximum K/S values was shown at 400 nm according to different fiber with color appearance of redish brown. Optimum pH and temperature of dyeing conditions was 4 and above $80^{\circ}C$, respectively. The brown colorants had a strong antioxidant activity compared to Butylated hydroxyanisole as standard and weak antimicrobial activity against E. coli. compared to kanamycin. Washing, rubbing, perspiration, dry cleaning and light fastness for cotton, nylon and silk dyed with the brown colorants were carried out by KS K method. Most of color fastness such as washing, rubbing, perspiration, and dry cleaning were represented as 4-5 grade. However, light fastness was reported as 2-3 grade. From this studies, brown colorants produced pine bark have a high potentials for natural dyeing on fabrics with antioxidant activity.