Lightfastness and flash photolysis of hydroxyanthraquinones

The photostability of the commercially important dye 1,2-dihydroxyanthraquinone (alizarin) is compared with that of four other structurally related hydroxyanthraquinones in both solution and polymer substrates. In solution the flash photolysis experiments showed that in a polar solvent, 2-propanol, the 1,2-hydroxy derivative is the least reactive. A similar trend in lightfastness (LF) is found when the dyes are applied to the highly polar substrate nylon-6,6.     

Lightfastness,phototendering and fluorescence of 3-methoxybenzanthrone

Studies have been made of the fluorescence quantum yields and lifetimes, the photostability and the phototendering behaviour of 3-methoxybenzanthrone in nylon 6,6 and in polyester to determine the nature of the primary process responsible for nylon phototendering. The results indicate that in a polar environment such as nylon 6,6 there is an increased probability of dye-substrate interaction. The results of a study of the fluorescence quenching by amines of varying ionisation potential indicates that the primary process responsible for nylon phototendering may be one of electron abstraction from the substrate.     

Lightfastness assessment of Levantine rock art by means of microfading spectrometry

The documentation of archeological sites requires the adoption of non‐destructive techniques to safeguard the unique legacy coming from prehistoric periods. This article tackles the assessment of lightfastness properties on a rock art site to determine the behavior of motif's color deterioration over time in Remígia Cave, Castellón (Spain), which is considered part of a UNESCO World Heritage Site. The measurements were performed using a microfade testing device to analyze the spectral characteristics and the aging properties of the colorant system and various substrates on site. Two scenarios have been identified depending on whether the lightness (L*) parameter of the rocky substrate changes or not in relation with the painted motifs. If the substrate remains stable without any change, red motifs containing iron oxide pigments will become more visible. If the substrate becomes lighter, the pigments will experience similar changes. Therefore, the contrast between paintings and support will be considerably enhanced.     

钛白粉在装饰纸体系中的耐光性研究

在装饰材料的生产过程中,钛白粉是重要的生产原料之一。钛白粉在装饰纸体系中具有重要的耐光性作用,将其应用在装饰原纸中会体现出较强的遮盖作用,对颜色以及耐光保色也会产生很大的影响。钛白粉具有高亮白以及高遮盖的特点,在装饰纸生产中被广泛的利用,不仅拓展了装饰纸的色彩空间,还会有效延长装饰纸制品的使用寿命。     

环境因素对染料日晒牢度的影响

本文综述了光、染料聚集态、染色深度、汗液及纤维种类等环境因素对染料日晒牢度的影响.并对各个因素所起作用的机理和方式作了详尽的阐述.指出染料的日晒牢度是受其化学结构和所处的外部环境及形态共同作用的,要根据不同的服用环境和需要来设计染料结构,以提高染料的日晒牢度.     

Lightfastness and spectroscopic properties of basic triphenylmethane dyes: Effect of the substrate

The lightfastness of five basic triphenylmethane dyes in cotton and acrylic fibres is compared with their primary photochemical behaviour on flash photolysis in appropriate model solvents. The low lightfastness of the dyes in cotton is paralleled by the observation of strong transient absorption in propan-2-ol whereas their higher lightfastness in acrylic fibre is paralleled by a lack of transient absorption in acetonitrile. The transient species is attributed to the triphenylmethane radical formed by electron transfer. Further, the relative importance of photoreduction and triplet sensitisation in dye fading is also examined using benzhydrol as a hydrogen-atom donor and benzophenone as a triplet sensitiser.     

活性黑KN-B的日晒牢度与染色工艺关系的研究

本文对活性黑KN-B(C.I.Reactive　Black 5)染纯棉织物的染料浓度,固色率和染色后处理条件与日晒牢度的关系,以及三原色拼色时对日晒牢度的影响做了探讨,同时对涤/棉织物两浴法染色的活性黑KN-B与分散蓝HBGL对其日晒牢度的影响做了研究。结果表明:活性黑KN-B染纯棉织物,其日晒牢度随染料浓度和固色率的增加而提高,且固色率为70％以上时,日晒牢度大幅度提高。染色后处理,碱剂与皂煮对日晒牢度亦有一定的影响。使用活性黑KN-B,活性红M-3BE,活性黄M-3RE拼色对织物染色时,在KN-B的浓度为1％以下,其日晒牢度随浓度的增加而下降,在KN-B的浓度超过1％时其日晒牢度随浓度的增加而升高;日晒牢度随活性红M-3BE与活性黄M-3RE的浓度的增加而增大。采用分散/活性二浴法染涤/棉织物,其日晒牢度随KN-B浓度的增加,先降低后升高,在染料浓度大于1％时,日晒牢度几乎不在变化;但其日晒牢度随分散蓝HBGL的浓度的增加而增大。     

Photopolymerization of pigmented thiol-ene systems

Photopolymerization kinetics and optical properties of pigmented thiol-ene coatings were investigated using photo-DSC, real-time FTIR, colorimetry, and AFM. Pigment has no deleterious effect on the unique ability of thiol-ene systems to photopolymerize in air. When trimethylolpropane tris-(3-mercaptopropionate) is incrementally added to tripropylene glycol diacrylate with and without calcium lithol rubine, a red organic pigment, the photopolymerization rate in nitrogen steadily decreases due to a shift in the polymerization mechanism from an acrylate homopolymerization to a thiol-ene copolymerization. However, the photopolymerization rate of pigmented and non-pigmented systems in air significantly increases with increasing thiol concentration, ultimately reaching a maximum at approximately 35 mole percent trifunctional thiol. The increase in rate is due to chain transfer from the non-reactive peroxy radical to the thiol. Thiol groups reduce oxygen inhibition to a greater degree than standard additives such as N-methyldiethanolamine, N-vinyl pyrrolidinone, and thioether containing trifunctional vinyl esters. For a typical acrylate based pigmented photocurable system, greater than 10 wt% photoinitiator is required to achieve a photopolymerization rate equivalent to a comparable thiol-ene system with 1 wt% photoinitiator in air. AFM and colorimetric data indicate that addition of trifunctional thiol has no deleterious effect on pigment dispersion and may in fact increase dispersion quality.     

Water permeability of pigmented waterborne coatings

Coatings are used in a variety of applications. Last decades more and more coating systems are transforming from solvent to waterborne coating systems. In this study the influence of pigments on the water permeability of a waterborne coating system is studied, with special interest in the possible interfacial layer of additives around the pigments. In our study an acrylate based binder is mixed with different glass sphere concentrations and sizes. Subsequently, the coating permeability is studied through wet-cup experiments and water uptake in the coating, either on a glass substrate or on wood, is monitored with NMR. These experiments show that water is absorbed more quickly by coatings containing glass spheres. From the experimental results it can be concluded that an interface layer around the pigment particles facilitates water migration and increases the effective diffusion. A modification of the effective medium theory is used to describe the observation and good agreement between experiments and theory is obtained. Both theory and experiment show that in a coating a layer around the pigments facilitates water transport and increases the effective diffusion constant.