New synergists for hindered amine light stabilizers

The development of hindered amine light stabilizers (HALS) in the seventies led to a tremendous increase in the outdoor use of polyolefins. Although since that time a great deal of insight has been gained into the UV-degradation mechanism of polyolefins and the mechanism of action of HALS, no new UV-stabilization chemistry has been discovered. In this paper, the most recent thoughts about the UV-degradation mechanism of polyolefins (initiation of photo-oxidation by polymer oxygen charge transfer complexes (CTCs)) and new insights into the mechanism of action of HALS stabilizers (quenching of these CTCs) are explored as a basis for designing new UV-stabilizers. A mechanism is proposed that explains the action of HALS as a quencher. Based on this mechanism several other possible quenchers (bridged amines) have been suggested. It is shown that these bridged amines are active as UV-stabilizers in films and plaques and that they show a synergism with HALS stabilizers. These new stabilizers are the most effective when they are present at concentrations higher than 0.1% and at higher concentrations of HALS. In such cases the addition of these synergists to a HALS stabilized system can lead to an improvement of a factor of 2-3.     

新型光稳定剂产品应用于水性醇酸涂料的研究

醇酸树脂普遍应用于工业涂料,其暴露在自然太阳光时,容易造成外观上颜色的变化和涂层劣化与粉化,目前这层保护主要是添加紫外线吸收剂(UVA)和酸性系统使用受阻胺光稳定剂(N-OR HALS)来达成。由于环保趋势,水性醇酸涂料已发展成为解决有关一般常用传统高VOC溶剂型涂料,它能够有效减少或不使用溶剂的优点,而环保型涂料所遭遇的挑战之一,是需要光安定剂来保护涂料预防光劣化产生。先针对2种不同类型水性受阻胺光稳定剂N-R HALS(高碱性)和N-OR HALS(弱碱性)混合水性醇酸涂料测试,试验结果显示:N-OR HALS适用于水性醇酸涂料系统。本文主要是有关于应用试验设计(DOE)试验手法,根据实验室人工加速老化试验结果显示,增加水性紫外线吸收剂Eversorb AQ6和水性受阻胺光稳定剂(NOR-HALS)Eversorb AQ5在水性涂料中的有效浓度,可以增强相对的保护效果,试验数据显示膜厚对减缓黄变影响而言也是显著因子,但效果不如添加水性光稳定剂产品有效。     

Migration of hindered amine light stabilizers in automotive clearcoats

The diffusion behavior of two hindered amine light stabilizers (HALS) [bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl)-sebacate and bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-sebacate] in an automotive clearcoat has been quantified via time-of-flight secondary ion mass spectrometry. Diffusion couples made from clearcoats with and without HALS allow for the estimation of the diffusion coefficient of one of the HALS. The high diffusion coefficient of one of the HALS contradicts the presence of HALS gradients in weathered coating systems. This discrepancy is ascribed to a decreasing diffusion coefficient of the HALS in the coating matrix due to a weathering-induced increase in the T _g of the clearcoat.     

新型光稳定剂应用于水性环氧涂料的研究

水性环氧涂料已发展成为解决一般常用传统高VOC溶剂型涂料的高污染问题,它具有有效减少或不使用溶剂的优点,而环保型涂料所遭遇的挑战之一是需要光稳定剂来保护涂料预防光降解产生。针对水性环氧涂料开发了一种新型复配型光稳定剂EVERSORB EP5,应用实验设计(DOE)研究结果表明:3种不同类型光稳定剂添加至2种不同类型溶液-水和水性环氧涂料中进行分散过滤试验,EVERSORB EP5分散效果最好,人工加速老化试验结果显示:增加EVERSORB EP5在水性涂料中的有效浓度,可以增强相对的保护效果,增加涂料的膜厚无法得到某种程度的保护效果。     

聚烯烃光稳定化技术进展

本文介绍了聚烯烃光稳定化的研究进展,并就受阻胺光稳定剂新的发展趋势及受阻胺光稳定剂与其它稳定剂之间的相互作用进行了较详细的讨论。     

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。     

Wirksamkeit sterisch gehinderter amine bei anspruchsvollen applikationen von polypropylen

The influence of some types of antioxidants on the efficiency of low molecular hindered amine light stabilizers (HALS) has been investigated in a comparison with the behaving of high molecular HALS. Most of the antioxidants used exhibit favourable influence. Convenience of both low and high molecular HALS in compounds depends on the character of the stabilised product and the technological conditions for its production.     

Study of some parameters responsible for the efficiency of hindered amine light stabilizers

The photooxidation of a styrene-butadiene-styrene block copolymer previously hydroperoxidized by reaction with singlet oxygen has been studied by measuring the increase of the carbonyl absorbance at 1720 cm^?1. Five different hindered amine light stabilizers (HALS) have been introduced into the polymer by diffusion from methanolic solutions, and their efficiencies as inhibitors of the photooxidation have been compared. The sequence of efficiency observed is: tert. amine > sec. amine > amino ether Under the experimental conditions used HALS are localized preferentially in oxidized regions of the polymer, and their efficiency can be correlated with their ability to catalyze the decomposition of clustered hydroperoxides. As a consequence, HALS are oxidized to nitroxy radicals that are the actual inhibitors of the photooxidation. A high local concentration of HALS in oxidized regions of the polymer also contributes to their efficiency, and this effect justifies the observation that some tertiary amines are more efficient than others.     

Active species in hydroperoxide decomposition by hindered amine light stabilizers and its reactivity with phenol

Hydroperoxide decomposition by hindered amine light stabilizers (HALSs) is an important process producing active HALS derivatives and has been studied energetically. The decisive active species of the decomposition, however, has not been proposed yet. In this article, HALS nitrosonium that forms in the decomposition of a hydroperoxide by HALSs and a ring‐opening product of the nitrosonium, a nitroso compound, are proposed as active species for hydroperoxide decomposition. Furthermore, the reactivity of the nitrosonium with phenols is discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1310–1317, 2006     

Synergistic effect of hindered amine light stabilizers/ultraviolet absorbers on the plasticized PVC during photo-irradiation

Two kinds of piperidine derivatives including a low-molecular weight (Wt. 481, T770) and a high-molecular weight (Wt. 2000–3100, C944) hindered amine light stabilizers (HALS) are added singly or with ultraviolet absorbers (UVA) in combination to plasticized poly(vinyl chloride) (PVC) samples. Digital photos, color changes, attenuated total refection-Fourier transform infrared spectra (ATR-FTIR), and mechanical properties are obtained to investigate the photostable effect of the light stabilizers on the plasticized PVC after artificial aging. PVC samples with HALS perform well at the first 400 h of irradiation in color change, FTIR, and mechanical properties, but at the last 400 h the photostability decreases. Besides, C944 performs better than T770, because C944 is a high-molecular weight UV stabilizer and has good extraction resistance. Plasticized PVC samples with UVA resist discoloring and photooxidation from the photo-irradiation. Excellent synergism is observed between the combination of HALS and UVA. PVC with HALS/UVA performs better than PVC with HALS and PVC with UVA in color differences, FTIR, and mechanical properties. The synergism is due to the different stages of functions between HALS and UVA. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

耐药型受阻胺光稳定剂的发展

介绍了耐药型受阻胺光稳定剂（HALS）的发展。针对低pKa值HALS,含缚酸剂的HALS,以及N-烷基化和N-烷氧基化HALS,详细叙述了典型品种的性能特点,并报道了耐药型受阻胺光稳定剂的最新研究成果。     

Long-term weathering behavior of UV-curable clearcoats: Depth profiling of photooxidation,UVA, and HALS distributions

The long-term weathering performance of two UV-curable clearcoat systems was studied using in-plane microtomy in combination with infrared spectroscopy, UV spectroscopy, and ESR spectroscopy. Oxygen transport characteristics were also studied using the half-time method. The photooxidation versus depth profile was highly dependant on the presence of hindered amine light stabilizers (HALS) for both coating systems. Ultraviolet light absorbers (UVA) had little effect on the photooxidation profile. A photooxidation gradient was formed in both clearcoats due to a reduction in oxygen solubility when compared to standard thermoset clearcoats. This gradient was only seen in formulations not containing HALS. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

各类稳定剂对聚乙烯薄膜光氧老化的稳定作用

研究了不同光稳定剂和抗氧剂及其配合使用、光稳定剂含量对聚乙烯薄膜耐光氧老化性的影响。结果表明：在各类光稳定剂中、受阻胺类稳定剂的效果最好;紫外线吸收剂与受阻胺配合使用可使膜的耐老化性有所提高;各类抗氧剂对聚乙烯膜的耐光氧老化性没有不利影响;光稳定剂含量增加,薄膜耐老化寿命提高。     

ABS的耐候老化研究

主要对丙烯腈–丁二烯–苯乙烯塑料(ABS)的不同耐候性能进行了研究,通过人工加速老化试验,对比老化前后色差变化,考察光稳定剂对ABS耐候性能的影响。结果表明,添加光稳定剂能够有效地改性ABS耐候性能;受阻胺光稳定剂与紫外线吸收剂复配使用对ABS有很好的耐候效果;适当地提高受阻胺光稳定剂含量有利于提高ABS的耐候性能。     

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.     

塑料光稳定剂的现状及发展动向

对近年来国内外光稳定剂的重要技术进步进行了综述。随着塑料应用领域的不断扩大,在各类塑料添加剂中光稳定剂增长速度最快,其中又以高稳定效能的受阻胺类光稳定剂居首位。我国目前光稳定剂的生产能力约为每年500吨,到2000年对光稳定剂的需要量约为3100吨。当塑料在高温下加工和在严酷环境下使用时,稳定剂会有不同程度的挥发和迁移,合成高分子量稳定剂是解决这个问题的途径之一。另外,可与基础聚合物产生键合作用的活性稳定剂的研究工作开展也很活跃。为适应效能和成本的要求还注意现有品种的并用和协同效应的应用。     

Migration of reactable UVAs and HALS in automotive plastic coatings

Loss of light stabilizers from automotive finishes can significantly reduce the durability of coatings on plastic substrates. Minimizing movement by retaining the stabilizers in the targeted layer can greatly improve coating longevity. This article examines the migratory patterns of a series of traditional UVA and HALS additives in fully formulated 1K silane crosslinked coatings applied over both plastic and steel substrates, comparing their migratory patterns to that of reactable light stabilizers containing hydroxyl functionality. Analysis of the coating layers with the various UVAs and HALS revealed that functionalization of the light stabilizer with reactable hydroxy groups can prevent migration into the plastic; whereas nonreactable light stabilizers migrate into lower coating system layers and even into the plastic substrate. The greatest extent of migration does not occur during initial cure of the wet coating, but during exposure. Significant depletion of the nonreactable light stabilizers from the topcoat occurs as early as 1500 hours of Xenon boro/boro exposure. This paper was awarded first place in the Shelby F. Thames Best Paper Award, at the 30th International Waterborne, High-Solids and Powder Coatings Symposium, February 26–28, 2003, in New Orleans, LA.     

Hindered amine light stabilizers in pigmented coatings

It is common practice to combine hindered amine light stabilizers (HALS) with UV absorbers (UVA) for optimal protection of coatings and plastics. The ratio of UVA and HALS strongly depends on the concentration of pigments (acting as UVA) used in the paint; that is, a clearcoatings require higher amounts of UVA, whereas opaque pigmented coatings require higher amounts of HALS. Here, especially basic HALS types can interfere with paint components like, for example, pigments due to acid/base interactions. In this article, we want to discuss the influence of HALS basicity on long-term performance in opaque white pigmented solventborne (SB) and waterborne (WB) coatings for industrial applications in correlation to the quality of the used TiO₂.     

受阻胺类光稳定剂改性文物保护材料B72

为了提高B72文物保护材料的耐光性能,采用HALS-622等6种受阻胺光稳定剂对丙烯酸类文物保护材料B72进行改性。结果表明,HALS-5060稳定剂在添加后及老化过程中颜色明显变黄,不宜用作B72改性材料。高相对分子质量(简称分子量,以下同)受阻胺HALS-622、HALS-944比低分子量受阻胺HALS-480、HALS-508和HALS-292稳定效果好,尤其是低碱性的HALS-622受阻胺。因此,采用高分子量、低碱性的受阻胺改性B72是延长其使用寿命、对文物进行有效保护的新途径。     

Theoretical and experimental assessment of UV resistance of high-density polyethylene: Screening and optimization of hindered amine light stabilizers

Hindered amine light stabilizers (HALS) are widely used chemical stabilizers for preventing polymer degradation. In this study, the effects of type of HALS and its content in high-density polyethylene (HDPE) over the stabilization process are investigated employing density functional theory (DFT) and experimental approach. The electrophilicity index of four types of commercial HALS are compared by DFT to select the most effective one. Besides, the HDPE sample containing a phenolic antioxidant and different contents of the selected HALS are experimentally exposed to UV irradiation. The effect of HALS content on the changes in chain microstructure and molecular weight of HDPE are evaluated using gel permeation chromatography and frequency sweep rheometry. In the absence of HALS, HDPE suffers degradation and the phenolic antioxidant causes chain scission. However, by adding HALS, the chain branching and crosslinking mechanisms are predominant. The results of FTIR, DSC, and tensile analyses follow similar trends, revealing that the best stabilization performance corresponds to adding 600 ppm HALS to HDPE.