Photofading Rate Research Articles

Depositing silica/polyvinyl pyrrolidone coating on sodium copper chlorophyllin dyed cotton fabric for photofading inhibition

Natural dyes’ mutual nature of being prone to photofading dramatically hinders their applications in the textile industry. Insulating coating with ability to prevent natural dyes from photofading is a solution to this issue. Basing on this principle, SiO2 nanoparticles (NPs) with the finest diameter of 50 nm were in-situ grown on the sodium copper chlorophyllin (SCC) dyed fabric pre-coated with polyvinyl pyrrolidone (PVP) to form a durable SiO2@PVP layer above the molecules of this natural dye, SCC. The SiO2@PVP layer is able to inhibit the photofading of SCC as the ΔE of the SiO2@PVP treated fabric caused by 10-h exposure to 300 W simulated sunlight irradiation is lowered by up to 52.6% when compared to the SCC dyed fabric. Results from finite element analysis proves the good electrical resistance of the SiO2@PVP layer while an approximately 77.6% decrease in the current density of the treated fabric was observed in the photocurrent response tests. By piecing the above results together, reduced generation of ROS is proposed as the explanation for the decline in the photofading rate of SCC covered by the SiO2@PVP layer. In addition, PVP successfully served as the bridge between the inorganic SiO2 NPs to the organic cotton substrate, leading to an improved wash fastness of the SiO2@PVP treated sample from 2‐3 to 4. The SiO2@PVP layer proposed in this study can serve the purpose of inhibiting the photofading of natural dyes over a prolonged period of time.

Dramatic Effect of Solvent on the Rate of Photobleaching of Organic Pyrrole‐BF2 (BOPHY) Dyes

AbstractThe photochemical stability of two symmetrical pyrrole‐BF2 (BOPHY) dyes has been assessed under continuous exposure to white light. The parent dye, lacking conjugated substituents, is highly stable when illuminated in a nonpolar film for prolonged periods but autocatalysis is observed such that the rate of degradation escalates with increasing exposure time. The rate of photofading is faster in solution and involves intermediate formation of a coloured product. The nature of the solvent exerts a small effect on the rate of bleaching. Under the same conditions, a BOPHY derivative equipped with both extended π‐conjugation and a high internal dipole moment displays a pronounced solvent effect. Here, the rate of photofading varies over a factor of 2 000‐fold on changing the solvent from cyclohexane to toluene. Most of the kinetic data can be explained in terms of polar and neutral resonance forms but, on the basis of NMR spectroscopy, it is concluded that toluene forms a weak complex with the dye that provides protection against photochemical damage.

Environmental impact on the light and perspiration stability of triazinylstilbene fluorescent brighteners on cotton fabrics

The fading of the triazinylstilbene fluorescent brighteners (TFBs) on cotton fabric under the conditions of exposure to sunlight and human sweat may reduce the visual quality and added value of the garment and also produce many toxic substances, which could threaten human health due to direct contact with skin. In order to investigate the light-fastness and perspiration stability of TFBs on cotton fabrics, three environmental factors of affecting the photo-fading of TFBs, i.e., ultraviolet irradiation, wet condition, and atmospheric constituents, were discussed according to AATCC standard. The results indicated that the effect of ultraviolet irradiation was more significant than its visible counterpart on the light and perspiration stability of TFBs on cotton fabrics. The light stability of TFBs was susceptible to the wet environment, and the presence of moisture accelerated the rate of photo-fading of TFBs. Furthermore, the study on the contribution of atmospheric constituents disclosed that the oxygen in the air together with the moisture of perspiration would make the synergistic effect on the fading of TFBs.

Improvement of light fastness of natural dye: effect of ultraviolet absorbers containing benzotriazolyl moiety on the photofading of red carthamin

While the contribution of ultraviolet absorbers to synthetic dyes has been investigated by several workers, there have been few studies pertaining to the use of functional ultraviolet absorbers as a means of improving the light fastness of natural dyes. In this paper, numerous potential ultraviolet absorbers were prepared to prolong the life of natural dye carthamin. The effects of these compounds in reducing photofading were examined on a polymer substrate. The use of commercial ultraviolet absorbers was not necessarily useful in improving the light fastness of the colour. However, benzophenone‐type ultraviolet absorbers containing a built‐in ultraviolet absorber moiety markedly retarded the photofading rate. It is proposed that 2,2′,4,4′‐tetrahydroxy‐5‐methylbenzotriazolylbenzophenone and its derivatives may be used as effective stabilisers in the fading of natural dyes.

Improving light fastness of natural dye: photostabilisation of gardenia blue

The photofading behaviour of gardenia blue on cellulose was investigated. A contribution of auto‐oxidation and singlet oxygen to that fading was suggested. The inhibiting effect of phenyl ester ultraviolet absorbers towards the photofading of gardenia blue was examined on cellulose. It has been found that the presence of a simple ultraviolet absorber is not of particular value in improving the light fastness of natural dye. The introduction of a singlet oxygen quenching group into an ultraviolet absorber can, however, have an important effect. The nickel complex of 1‐benzoyloxynaphthalene‐3‐sulphonic acid was very effective in reducing the rate of photofading.

Relationship between photofading and chemical structure of disperse azo dyes on nylon fabric†

The initial rates of photofading for 30 disperse azo dyes on nylon fabric upon exposure to a carbon arc in air have been analysed by formulating a kinetic equation that describes azo scission via the disproportionation reactions and intramolecular H‐transfer by two kinds of hydrazinyl radicals and the conversion of a nitro group to a nitroso group via the disproportionation reaction of nitrosyl hydroxide radicals. The five reaction rate constants are discussed in terms of the heats of reaction by calculating the heats of formation for the reactants, intermediates and products of each reaction using the PM5 method. Phenylazo‐ and thiazoleazo‐N,N‐substituted anilines and phenylazo‐pyridones exhibited large rate constants of multiple terms, while phenylazo‐phenols had the highest light fastness and very small rate constants for the disproportionation reactions of hydrazinyl radicals. Photofading on nylon fabric was primarily controlled by the thermal reactions of photo‐induced monohydrogenated dye radicals, which occurred via one or two primary multiple routes.

홍화 황색소를 이용한 모염색의 최적화

본 연구는 염색 공정의 표준화와 재현성을 확립하기 위해 홍화 황색소의 모섬유에 대한 염색성을 조사하는데 목적이 있다. 홍화 황색소는 물로 추출한 후 농축, 동결건조하여 분말상태로 만들어 사용하였다. 염색 온도 및 시간, 염료 농도, 염액의 pH 등에 따른 염착성과 색상 변화에 대해 조사하였으며, 세탁 및 일광견뢰도를 평가하였다. 염착량은 <TEX>$50^{\circ}C$</TEX>까지 서서히 증가하다가 이후 급격히 증가하여 <TEX>$90^{\circ}C$</TEX>에서 최고 값을 나타냈다. 염착은 초기 10분 이내에 빠르게 일어났으며 이후 서서히 증가하다가 40~60분 사이에 평형에 도달하였다. 염료 농도가 증가함에 따라 염착량이 계속 증가하여 점점 진하고 어두운 노랑색이 되었다. 산성 조건에서 염착이 잘 되었으며 pH 3.0에서 최대염착량을 보였다. 얻은 결과를 근거로 최적 염색 조건은 <TEX>$90^{\circ}C$</TEX>, 40분, pH 3.5으로 설정하였으며, 최적 조건에서 염색한 시료들 간의 색차는 0.53~1.75로서 재현성이 우수하였다. 후매염은 염착성 증진에 효과가 없었으나, 다양한 톤과 농담의 노랑색을 얻을 수 있었다. 세탁(드라이크리닝)견뢰도는 4/5등급으로 좋은 편이었으나 20시간 조사 후 일광견뢰도는 Fe과 Cu매염한 경우 3/4등급으로 색차가 가장 적었다. 결과를 종합해 볼 때 매염제가 색상톤을 다양하게 하는 효과는 있었지만, 염착량과 견뢰도 향상에 기여하지 못하였다. 홍화 황색소는 모염색에서 매염제 없이 만족스러운 결과를 얻을 수 있고, 따라서 환경에 피해를 주지 않을 것으로 사료된다. This study investigated the adsorption of safflower yellow dye on wool protein fiber and the optimum dyeing conditions to test color reproducibility. In addition, the effects of mordants on dye adsorption, color, fastness, and photofading rate were also studied. The prepared dye in powder form was characterized with UV-vis spectroscopy and FT-IR spectrometric analysis. The color of dyed fabrics was characterized by CIE <TEX>$L^*a^*b^*$</TEX> coordinates, H V/C, and K/S values. The color reproducibility of the dyed wool fabrics was examined. The amount of dye adsorption increased and also, the shade of the dyed wool fabrics became deeper and more saturated with increasing temperature, time, and dye concentration. The maximum color strength was obtained at pH 3.0. The shade of dyed wool fabrics ranged from light yellow to dark mustard yellow as the pH of the dye bath shifted from alkaline to acidic. Color reproducibility was reliable with color differences in the range of 0.53~1.75. Fastness to dry cleaning was relatively good at 4/5 rating irrespective of mordanting. Fe and Cu mordants showed the least color change of the dyed wool fabrics after exposure to light. Mordants did not contribute to improve dye uptake and color fastness, although they made variations in color tone. Safflower yellow dye can be used satisfactorily without mordants and will not cause damage to the environment.

Analysis of the catalytic fading of pyridone-azo disperse dyes on polyester using the semi-empirical, molecular orbital PM5 method

The catalytic fading of combination dyeings on polyester fabric of six pyridone-azo and one quinolone-azo yellow disperse dyes imparted by C.I. Disperse Blue 165 as a result of exposure to a carbon arc in air was analyzed in terms of reactivity ( k 0) towards singlet oxygen and the photosensitivity ( f) of the dyes. Based on the assumption that the rate of photo-fading of single dyeings is proportional to the product of k 0 and f, the fading behavior of both single and mixture dyeings was explained. The k 0 values for the seven azo dyes could be correlated to the sum of electrophilic frontier densities determined using the PM5 method. The nitro groups in the pyridone-azo dyes decreased the reactivity of the electron density in parts of the diazo component. Disperse dyes with excellent light fastness on polyester exhibit low values of both f and k 0. The f values observed for the combination dyeings did not show simple additivity.

Improving light fastness of natural dyes on cotton yarn

The objectives of this study were to evaluate the light fastness of selected natural dyes (madder, weld and woad) and the effect of some commonly used antioxidants and UV absorbers on the light fastness of these dyes. The photofading rate curves of madder and weld fixed on cotton correspond to type II fading rate curves described by Giles. These results are in concordance with those of Cox-Crews. The woad presents a type III fading rate curve, similar to the indigo fading rate curve presented by Cox-Crews. A poor light fastness of the three natural dyes in comparison with synthetic ones is established beyond question. Nevertheless, the use of some additives can improve this default of natural dyes. In all the cases, the use of UV absorbers or antioxidants improved the light fastness of dyed fabrics. The most effectives were the vitamin C and the gallic acid.

Improving the light fastness of dyed nylon fabrics using nickel arylsulphonates

Various nickel arylsulphonates were synthesised and their protecting effects on the photofading of CI Basic Violet 3, CI Acid Red 94, CI Acid Red 87 and CI Acid Blue 74 examined on nylon fabric. The rates of photofading of the dyes were remarkably suppressed in the presence of nickel salts, while the addition of ultraviolet absorbers and conventional stabilisers afforded little retardation of the rate of fading. The antimicrobial activity against two species bacteria of nickel salts was also examined. This aftertreatment technique was shown to be safe for the environment and human health.

Effect of stabilisers containing a singlet oxygen quencher on the photofading of dyes in a polymeric substrate

New ultraviolet absorbers and phenolic antioxidants bearing a nickel carboxylate group have been prepared and their ultraviolet–visible absorption spectra measured in ethanol. Their inhibiting effect on the fading of dyes was examined in cellulose acetate film. It has been found that the presence of a simple ultraviolet absorber or phenolic antioxidant is not of particular value in improving the light fastness of dyes. The introduction of a singlet oxygen‐quenching group into an ultraviolet absorber can however have an important effect. The nickel complex of salicylic acid salicylate was very effective in reducing the rate of photofading.

Effect of Phenyl Ester UV Absorbers Bearing a Singlet Oxygen Quencher on Photofading of Crystal Violet in a Polymer Substrate

Various kinds of phenyl ester compounds are synthesized and their uv-visible absorption spectra are measured in ethanol. Their protective effects against fading of Crystal Violet are also examined in cellulose acetate film. The application of simple uv absorbing compounds is not necessarily useful for improving the light fastness of triphenylmethane dyes. Nickel 4-benzoyloxybenzenesulfonate or 2-benzoyloxynaphthalene-6-sulfonate, however, almost perfectly suppress photofading rate of Crystal Violet. The introduction of a singlet oxygen quenching group into the uv absorber plays a very important role in improving the light fastness of triphenylmethane dyes.

Photofading, photosensitization and the effect of aggregation on the fading of triphenodioxazine and copper phthalocyanine dyes on cellulosic film

The photosensitized oxidation of four triphenodioxazine (TPDO) reactive dyes and a copper phthalocyanine (CuPc) reactive dye on cellulosic films by Rose Bengal (RB) was examined in aqueous solution under aerobic conditions. The rates of photo-oxidation of 4,11-bis(vinylsulfonyl)TPDO dyes were smaller than those obtained for 3,10-bis(disubstituted triazinyliminoethylimino)TPDO dyes. The rates of photofading of the four TPDO dyes and a CuPc dye on cellulose were similar in the order to the rates of the photosensitized oxidative fading with RB. Photo-oxidation left the aromatic residue from TPDO ring along with the reactive anchor bound to cellulose. No aggregation effect was observed on the fading of TPDO dyes and a CuPc dye on cellulose. The photosensitivity of the TPDO dyes was very small, this being estimated by the photosensitized fading of an aminopyrazolinylazo dye (Yellow dye) on cellulosic films dyed in admixture with TPDO dyes by use of a yellow filter to shield Yellow dye on exposure. It is concluded that the good light-fastness of the TPDO dyes on cellulosic substrate is attributed to the very small photosensitivity in spite of their relatively large ease with which they are oxidized.

Improvement of the light fastness of natural dyes: the action of singlet oxygen quenchers on the photofading of red carthamin

While the contribution of singlet oxygen quenchers to synthetic dyes has been investigated previously by several workers, there have been few studies pertaining to the use of singlet oxygen quenchers as a means of improving the light fastness of natural dyes. In this paper, the influence of various additives on the photofading of carthamin has been examined in cellulose acetate film. The rate of photofading of the colour was remarkably suppressed in the presence of nickel hydroxyarylsulphonates, while the addition of UV absorbers afforded little retardation in the rate of fading.

The effect of hydroxyarylbenzotriazoles containing a singlet oxygen quenching moiety on the photofading of dyes on a polymer substrate

Numerous potential UV absorbers were synthesized to prolong the life of colorants for printing and imaging systems. The effect of these compounds in reducing photofading was examined on a polymer substrate. The use of a simple UV absorber was not necessarily useful in improving the light fastness of the colorants. Nickel hydroxyphenylbenzotriazolesulfonates, however, markedly suppressed the photofading rate of a triphenylmethane dye. The fading of an xanthene dye was completely depressed in the presence of nickel 2-(5-methyl-2H-benzotriazol-2-yl) naphthol-4-sulfonate. It is proposed that nickel complexes of hydroxyphenylbenzotriazolesulfonic acid and its derivatives may be used as effective stabilizers in the fading of indicator dyes for printing and imaging systems.

The light stability of azo dyes and azo dyeings IV. Kinetic studies on the role of dissolved oxygen in the photofading of two heterobifunctional azo reactive dyes in aqueous solution

Heterobifunctional reactive derivatives of two previously studied azo chromophores were exposed to light in aqueous solution. In the presence of artificial perspiration, the initial and final rate of photofading depended on the oxygen level of the dye solution. An initial low rate of light-induced dye decomposition was followed by a much higher rate in the final stages of exposure. The lower the initial oxygen concentration the shorter the initial period low dye degradation and the higher the rate of photodegradation in the final stages. Light-induced dye decomposition follows first order kinetics. A reductive mechanism for perspiration assisted, light-induced degradation was supported by results from the photofading of the dyes in the presence of reductive compounds.

Wavelength dependence of light-induced fading and free radical formation in azoreactive dyes

Light-induced stable free radicals (SFRs) were detected in azoreactive dyed cotton fabrics. Extremely slow photofading occurred under exposure to light of relatively long wavelength. The rate of photofading and SFR formation depend on the structure of the dye. Some of them show little drop in the rate of fading with the increasing wavelength, whereas others show nearly negligible changes under incident light of relatively long wavelength. In general a high rate of photofading was found when the SFR concentration was low.

Synthesis and photostability of functional squarylium dyes

Various symmetrical and unsymmetrical squarylium dyes have been synthesized and characterized with the aid of IR spectroscopy and solvatochromism. The photofading of squarylium dyes has been investigated in solution and in polyvinylbutyral (PVB) film with carbon arc Fade-Ometer. The photostability of squarylium dyes increases with the electron-with-drawing power of substituent groups at the indoline moiety. The rates of photofading of these dyes were remarkably suppressed in the presence of hydroxycarboxylic acid metal salt, while the addition of UV-absorber afforded little retardation of the rate of fading.

Photofading Behavior of Triazinylaminostilbene Fluorescent Brightener in Cellophane

The photofading behavior of CI Fluorescent Brightener 85 (FB 85) is investigated on cellophane. The initial photofading reaction of FB 85 on cellophane is trans-cis isomerization, and the subsequent reaction is assumed to be photodegradation. The initial photofading rate of FB 85 on cellophane is accelerated by brightener concen tration and atmospheric moisture, whereas the addition of sodium carbonate to the dyebath retards photofading. A kinetic analysis suggests the participation of a bimo lecular reaction in addition to photoisomerization through a monomolecular reaction. The contribution of the bimolecular reaction increases as the moisture content in creases. Added salt reduces the contribution of the bimolecular reaction in photofading of FB 85 on cellophane.

固体マトリックス中におけるローダミン６Ｇの光退色

It has been tried to solidify dye laser, but the attempt was not succeeded, yet, for highly fading speed of the laser dyes. We investigated the photofading rate of Rhodamine 6G, the dye for dye laser, in vinyl polymer matrices, and it was found that the fading rate was proportional to e value of the monomer which composes of the polymer.It was also found that the formation of inclusion complex by cyclodextrin was not effective in such polymer matrix containing poly (methyl methacrylate).It was already reported that the photofading of Rho damine 6G in poly (methyl methacrylate) was reduction reaction. This phenomena were due to the fact that the hydrogenated position of Rhodamine 6G was not included in cyclodextrin. On the other hand, the photofading rate of Rhodamine 6G in poly(vinyl alcohol) matrix was very slow and was further decreased by cyclodextrin.