The mechanism of photoprotection of wool by UV absorbers of the 2-hydroxybenzophenone class

The mechanism by which sulfonated 2-hydroxybenzophenone ultraviolet (UV) absorbers protect wool fabric against photoyellowing has been studied. The absorption and luminescence properties of two 2-hydroxybenzophenone-5-sulfonates and four 2-hydroxybenzophenone-2′hyphen;sulfonates are compared. The 2-hydroxy-benzophenones are nonfluorescent in wool, but they all show phosphorescence at room temperature. The phosphorescence is attributed to the phenolate anion produced by ionization of the hydroxyl group. The nature of substituents in the 3-position and 4-position of the phenolic ring is important in controlling the formation of luminescent species which may initiate unwanted photochemical reactions in wool. The protective screening effect of each absorber in wool fabric has been determined theoretically, using a method of analysis based on diffuse reflectance spectroscopy; the results are compared with the values determined experimentally by measuring the changes in yellowness that result when treated and untreated fabrics are exposed to fluorescent sunlamps (maximum energy at 310 nm). In all cases, UV screening was shown to be the important mode of photostabilization. The levels of photoprotection were much higher than those reported previously for treated fabrics that were exposed for long periods to simulated sunlight, behind glass. Possible reasons for the poor long-term performance of the 2-hydroxybenzophenones in wool are discussed.     

高性能水性复配型光稳定剂应用于南方松表面处理

木质素受到阳光照射下很容易劣化,要保留天然木器纹路和颜色的外观,目前工业界常用的方式是在木器的表面涂上一层添加有紫外线吸收剂(UVA)和受阻胺光稳定剂(HALS)的保护清漆。但是这种涂布方式的保护效果比较有限,实验结果显示,在涂布清漆之前,先将木器的表面进行防止老化处理,可以更有效地延长保护时间。文章针对水性透明清漆开发了一种复配型光稳定剂Eversorr AQ1,在南方松的材质表面进行一层处理。人工加速老化试验结果显示,增加Eversorb AQ1在透明清漆里面的有效浓度,可以增强相对保护效果,但是如果在涂布清漆之前先在南方松的表面用光稳定剂W1处理,其耐候性可以比未处理过的增加50%。虽然实验数据显示增加清漆涂层膜厚也可以得到某种程度的保护效果,但是与增加Eversorb AQ1的有效浓度,或者先将木器的表面进行处理,增加清漆的涂膜厚度并不是一种最佳的选择。     

Influence of different types of UV absorber/UV stabilizer combination on the photodegradation of PC/ABS blend

The polycarbonate/poly(acrylonitrile butadiene styrene) blends, (PC/ABS), are mainly degraded by sunlight known as photodegradation when exposed to outdoor conditions. It is the ultraviolet (UV) radiation that is responsible for the degradation of the blend. To stabilize against the harmful UV radiation and to scavenge the radical species which arise from UV or thermally induced degradation of the PC or the ABS, UV absorbers, and UV stabilizers are used. In this article three different UV absorbers namely, Tinuvin 1577—hydroxyphenyl triazine type, Cyasorb 5411—benzotriazole type, Uvinul 3030—cyanoacrylate type, and two different UV stabilizers, Tinuvin 765—monomeric hindered amine type, Tinuvin 622—oligomeric hindered amine were compounded in different combinations with PC/ABS blend at 240°C using a twin screw extruder. Accelerated aging of the compounded sample was done by Atlas Suntest apparatus. The photodegradation studies were done using UV–vis, attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy, and Yellowing index measurement. The molecular weight of the compounded sample before aging was determined by gel permeation chromatography (GPC). It was found that samples protected with hydroxyphenyl triazine type UV absorber and oligomeric hindered amine show the best result for decreasing the degradation products, oxidation rate, and yellowing of the PC/ABS blend. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Direct coloration of textiles with photochromic dyes. Part 3: dyeing of wool with photochromic acid dyes

Wool dyed with two isomeric water‐soluble spirooxazine‐based photochromic acid dyes, which were specifically designed and synthesised for direct application to protein and polyamide substrates, showed reversible change from a pale yellowish colour to blue when exposed to sunlight or UV light. With the first dye, significantly higher photochromic colour change was obtained when the wool was bleached, a feature attributed to a more open fibre structure which may facilitate penetration of the non‐planar dye anion and also the photocoloration reaction which requires a change in molecular geometry. Experimentation demonstrated that the optimum conditions for application of this dye to wool was from an aqueous dyebath at neutral pH and a temperature of 60 °C. An investigation using HPLC demonstrated that the dye was susceptible to decomposition in aqueous solution at higher temperatures and at lower pH values. The second dye was also applied to wool fabric to give a fabric with similar photochromic properties. The technical performance of the dyed fabrics, in terms of washfastness and photostability, was assessed.     

Stabilization of polypropylene

Antioxidants and UV absorbers are vital to the commercialization of polypropylene because of their influence on this polymer's light stability, heat or oxidative stability, processing stability, and gas fading due to nitrogen oxides. The effects of these stabilizers are measured in terms of polypropylene's initial color, color retention, and retention of physical properties when the polymer is exposed to direct weathering and to elevated temperatures. The relative washfastness or resistance to extraction by aqueous systems under various laundering conditions is another important, measurable property of UV absorbers and antioxidants in polypropylene. Such measurements are usually made using stabilized polypropylene molded plaques and monofilaments containing UV absorbers, antioxidants and, often, combinations of the two.     

UV absorber aftertreatment to improve lightfastness of natural dyes on protein fibres

The effect of a UV absorber on the lightfastness of natural dyes has been investigated. Wool and silk fabrics, dyed with natural dyes with or without mordants, were aftertreated with two UV absorbers. This treatment improved the lightfastness of the mordant-dyed fabric without affecting its colour or shade. The extent of photofading was evaluated by measuring the colour difference, Δ E , of the dyed sample before and after a 20 h period of irradiation under a xenon arc lamp. The uptake of the UV absorber on wool was much higher than that on silk.     

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.     

双功能受阻胺与紫外线吸收剂并用的协同效应研究

本文用IR、UV、ESR、TLC等方法研究了新型的双功能受阻胺光稳定剂,Tinuvin-144 [2-(4′-羟基-3′,5′-二叔丁基)苄基-2-正丁基丙二酸五甲基哌啶醇酯]与紫外线吸收剂,UV-531(2-羟基-4-正辛氧基二苯甲酮)和UV-327(2-[2′-羟基-3′,5′-二叔丁基]-5-氯 代苯并三唑)并用体系对聚丙烯光稳定化的并用效应。结果表明,Tinuvin-144与UV-531,UV-327并用时均具有良好的协同效应,144对531,327或531,327对144的光分解均具有相互的保护作用。结果还表明,144与531或327无论在模拟体系或聚丙烯中,在诱导期内均不存在促使他们消耗的化学反应,提出了协同作用的机理。     

Synergistic profiles of chain‐breaking antioxidants with phosphites and hindered amine light stabilizers in styrene–ethylene–butadiene–styrene (SEBS) block copolymer

The photostabilization of poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS) by phosphite/p‐hydroxybenzoate antioxidants and hindered phenol/hindered amine light stabilizers (HALS) was studied by using a variety of spectroscopic methods, including FTIR, UV, and luminescence spectroscopy coupled with crosslinking and hydroperoxide analysis. The results were compared with those obtained for hindered phenols and their combinations with phosphite antioxidants. All the stabilizing packages stabilized the SEBS in terms of the inhibition of discoloration and the formation of hydroperoxides, acetophenone, and oxidation products, as well as chain scission and disaggregation of the styrene units. Although phosphite/p‐hydroxybenzoate combinations appeared to reduce the formation of oxidation products, they did not show any remarkable enhancement in long‐term stabilization with respect to phenolic/phosphite antioxidants. On the other hand, strong synergistic profiles were found with the HALS. Mobility and diffusion impediments in the polymeric material appeared to play an important role in the stabilizing activity of the HALS. J. VINYL. ADDIT. TECHNOL. 12:8–13, 2006. © 2006 Society of Plastics Engineers     

Synthesis and three dimensional pattern finishing properties of blocked isocyanate prepolymers

Two kinds of blocked isocyanate prepolymers (BIPs), BIP-S and BIP-H, were synthesized, and three dimensional pattern (3D) finishing properties of BIPs were investigated with several techniques. As a result, the BIP-H exhibited higher glass transition temperature, tensile strength, and tensile modulus than did BIP-S. The combination of two kinds of antioxidants resulted in good performance that prevented yellowing at high temperature and exposure to sunlight. 3D pattern finished cotton fabrics coated with BIP-S showed a higher transparency than that of non-coated cotton fabrics. Both cotton fabrics coated with BIP-S and those coated with BIP-H showed excellent repellency to alkali solution.     

Investigation into the synergistic effect between UV/ozone exposure and peroxide pad—batch bleaching on the printability of wool

The synergistic effect between UV/ozone exposure and hydrogen peroxide pad-batch bleaching on the printability of wool has been investigated. The combination treatment can achieve similar printability to that of chlorinated wool but with the added benefits of a whiter base and no formation of adsorbable organohalogens. X-Ray photoelectron spectroscopy and static secondary ion mass spectrometry indicate that the UV/ozone exposure disrupts surface lipids and disulphide bonds, while vibrational spectroscopy (FT-IR and FT-Raman) shows the formation of cysteic acid on the combination treated wool. The process parameters of the peroxide pad-batch bleaching for UV/ozone exposed wool were optimised.     

Time optimization of ultraviolet–ozone pretreatment for improving wool fabrics properties

Wool fabrics were exposed to ultraviolet (UV)–ozone treatment for different periods. After exposure, the fabrics were analyzed by Fourior transform infrared spectroscopy (FTIR). Also, the crystallinity and amorphousity regions were followed by an X‐ray diffraction technique. The results were correlated by mechanical properties measurements. After a certain period of exposure, the dyeability and printability were improved because these abilities are strongly related to the percentage ratio of crystallinity regions to amorphousity regions in wool fabrics. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1469–1476, 2002     

Improving the photostability of bleached wool without increasing its yellowness

Bleached wool is rapidly yellowed by exposure to the UV radiation present in sunlight. The conventional application of a water‐soluble hydroxyphenyl benzotriazole UV absorber (such as UVFast W) to bleached wool reduces its rate of photoyellowing but has a negative impact on the whiteness of the bleached wool, largely cancelling out the improvements in whiteness achieved during bleaching. However, if the UV absorber is applied to peroxide‐bleached wool from a reductive bleach bath, white wool with improved photostability to sunlight and UV radiation can be obtained.     

Photoyellowing of wool. Part 1: Factors affecting photoyellowing and experimental techniques

The yellowing of wool exposed to sunlight is a serious commercial shortcoming compared to cotton and synthetic fibres, particularly when photostable brilliant whites and bright pastel shades are required. Part 1 of this review discusses the effects of light on wool keratin and the factors that affect the rate of photoyellowing, including oxidative bleaching, fluorescent whitening and the presence of moisture. The effect of variation of the wavelength of light, particularly attenuation of the ultraviolet wavelengths in sunlight by window glass that can result in photobleaching of wool is described. The experimental techniques that have been used to study the complex photochemistry involved in yellowing, and to identify the nature of the yellow chromophores formed, are also discussed. Part 2 of the review will focus on the photochemical mechanisms involved, and discusses potential ways for improving wool's photostability.     

Antioxidant‐assisted coloration of wool with xanthophylls extracted from corn distillers’ dry grain

Xanthophylls extracted from corn distillers’ dry grain were successfully applied to dye wool fabrics. As a readily available and cost‐effective grain processing byproduct, corn distillers’ dry grain contains appreciable amounts of isolable xanthophyll colourants, which can potentially be used in textile coloration. However, the application of xanthophylls as textile colourants has been limited, possibly owing to their hydrophobic nature and lack of stability at higher temperatures. In the present work, dyeing of wool fabrics with xanthophyll dyes was performed in the presence of a solubilising agent (diglyme) and an antioxidant (butylated hydroxytoluene). Dyeing conditions were modelled and optimised by the one‐factor‐at‐a‐time method and response surface methodology. Depth of shade of the wool fabrics dyed with 0.33 g l^?1 of xanthophylls could be as high as 10.9 ± 0.5, while the colour fastness to laundering and crocking was better than grade 4. The prominent effect of butylated hydroxytoluene on depth of shade (K/S) was further studied using functionally and structurally related model compounds. The K/S‐enhancing ability of butylated hydroxytoluene was found to be a synergistic result of its antioxidising and complexing abilities. Lab‐extracted xanthophylls of various purities were applied to wool fabrics using the optimised dyeing and aftertreatment conditions. Depth of shade but not colour fastness was significantly affected by the impurities in xanthophylls extracted from corn distillers’ dry grain. The strategy developed by this work not only extends the scope of xanthophyll application into textile coloration but also could be used for other hydrophobic and unstable natural colourants.     

Deterioration of polyaramid and polybenzimidazole woven fabrics after ultraviolet irradiation

In this study the degradation of woven fabrics of meta‐aramid and the blend of para‐aramid and polybenzimidazole fibers when exposed to environmental conditions has been investigated under accelerated ageing conditions. Generally, these polymeric materials have been used for the outer layer of protective clothing, particularly for fire‐fighting. The performance of these fabrics plays an important role in preventing burn‐injuries to fire fighters. Frequent exposure of these materials to various environmental conditions (especially sunlight) can degrade the polymeric chain and affect their performance properties. Hence, the degradation of the fabrics has been studied in terms of loss of tensile and tear strength; reduction in abrasion resistance; and extension at break. It was observed that ultraviolet (UV) irradiation negatively impacted on the mechanical properties of both the polymeric materials significantly. This can be attributed to chemical changes in the polymeric chains due to the photo‐oxidation of the polymer. Scanning electron microscopy images revealed surface decomposition of the filaments due to UV irradiation. Exposure of polybenzimidazole resulted in rapid loss of mechanical and chemical properties in comparison with meta‐aramid. However, decomposition and degradation of polybenzidimazole was not statistically significant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43073.     

不饱和树脂玻璃钢复合材料防老化研究进展

综述了不饱和树脂基玻璃钢复合材料(GFRP)防老化方面的新近研究进展,包括新型GFRP表面涂层及不饱和树脂的防老化添加剂(紫外线吸收剂、受阻胺光稳定剂和抗氧剂等)及树脂的改性。将抗氧剂和其他添加剂(例如某些环氧化合物)并用,可取得较好的效果。     

A novel strategy to improve the dyeing properties in laccase-mediated coloration of wool fabric

Enzymatic coloration of fabrics has received worldwide attention in recent years. In order to improve the dyeing properties of enzymatically coloured fabrics, a novel strategy using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), a biological coupling agent, to pretreat wool fabric was employed in this paper. Enzymatic coloration of wool fabrics with syringic acid was carried out in the presence of laccase from Trametes versicolor. The effect of different periods on laccase-catalysed polymerisation of syringic acid was examined by UV-vis spectroscopy. Enzymatic coloration results of dyed wool fabrics were evaluated by means of K/S value and colour difference (∆E*). Process parameters, including the dosages of syringic acid and incubation time, that influenced the colour depth were studied. Meanwhile, the colour fastness and levelness of dyed wool fabrics were tested. The results showed that the UV-vis absorbance of reaction solution increased as oxidation time elapsed, and a new peak appeared at 360 nm. After pretreatment, the K/S values and colour difference values of wool fabrics dyed with poly(syringic acid) improved appreciably compared with the control samples without any pretreatment. Moreover, pretreated wool fabrics showed better dyeing fastness and levelness than control samples.     

一种毛用无醛固色剂的合成及应用

将对苯二酚进行磺化后与环氧氯丙烷等反应,合成了一种新的无醛固色剂。用其对染色后的羊毛织物、羊毛/绢丝混纺织物进行固色并检测了固色后织物的综合性能。结果表明,使用该固色剂固色后的羊毛、羊毛/绢丝混纺织物的干、湿摩擦牢度等综合性能有明显提高。     

加氢润滑油基础油光稳定剂的研制

应用正交试验设计的方法,研究了自制的紫外辐射吸收剂、受阻胺类光稳定剂及抗氧剂对兰州石化总厂生产的125N加氢润滑油基础油抗光氧化降解性能的影响.发现以上各种添加剂均能提高加氢润滑油基础油抗光氧化降解的能力.在相同的辐射剂量下,添加四甲基受阻胺类光稳定剂的加氢基础油抗光氧化降解的能力优于添加五甲基受阻胺类光稳定剂;添加苯并三唑型紫外辐射吸收剂比添加二苯甲酮型紫外吸收剂的加氢基础油抗光氧化降解的能力强;紫外辐射吸收剂与受阻胺类光稳定剂之间以及紫外辐射吸收剂与抗氧剂之间均存在协同作用.并且发现,四甲基受阻胺类光稳定剂与酚类抗氧剂之间存在协同作用,而五甲基受阻胺类光稳定剂与酚类抗氧剂之间存在反协同作用.评价结果表明:添加自制的高效无灰复合型光稳定剂1.5g·L-1可使兰州炼油化工总厂生产的125N加氢润滑油基础油保持良好的光稳定性,其透光率、色度均优于添加2 g·L-1目前最好的有机镍盐配合物型光稳定剂.