How to control dirt pick-up of exterior coatings

The composition of dirt and the tendency of coatings to pick up dirt are determined largely by the location. The factors affecting the tendency of coatings to pick up dirt are varied and complex. That is why the problem of dirt pick-up on exterior coatings can only be resolved satisfactorily by optimisation of the paint formulation as a whole (PVC, type of formulation, surface texture) and of all the raw materials (binders, pigments, fillers, additives).     

涂液浓度对Ru-Ti-Ir氧化物阳极涂层性能的影响

应用热分解法制备了由不同浓度涂液形成的Ru-Ti-Ir氧化物阳极涂层,SEM,EDX,XRD、强化电解寿命、极化曲线、循环伏安和电化学阻抗等测试表明,涂液浓度对阳极涂层的表面形貌有着很大的影响,但不甚影响其析氯极化过程.随着涂液浓度的增加,阳极涂层的伏安电量和双电层电容都出现先降低后增加的变化趋势.     

有机氟材料的结构与性能及其在涂料中的应用

高性能、低（无）污染是当今涂料发展的主要趋势，氟树脂独特的结构特点使它具有很高的耐热性，耐化学性和耐候性，独特的电学性能，优良的表面性能和光学特性，从而使其成为可能同时具有这两项要求的材料之一，本文着重介绍了目前几种最主要的氟树脂的结构与性能，如聚四氟乙烯（PTFT），聚偏二氟乙烯（PVDF）、氟烯烃／乙烯基醚共聚树脂（FEVE）及全氟聚醚 （PFPE）等。另外还对当前国内，外含氟高聚物在涂料应用上的研究进展作了一些介绍。     

超疏水涂层表面粗糙结构对防覆冰性能的影响

结冰给交通、电力输送和航空等领域带来极大的安全隐患,研究防覆冰技术具有重要的应用价值。目前最具前景的防冰方法是涂层防冰,本文介绍了疏水涂层的构建方法,阐述了涂层疏水性和疏冰性之间的关系;重点论证了涂层表面粗糙结构对其防覆冰性能的影响,指出防覆冰涂层研发中存在的问题,并对该领域的发展趋势进行了分析和展望。     

Complexation of an acrylic resin by tertiary amines: synthesis and characterisation of new binders for antifouling paints

Antifouling coatings are the most reliable way to prevent biofouling of immersed surfaces. As concerning the high toxicity of organotin paints, the tendency is the development of coatings, which do not present environmental risks. In this work, we prepare binders from modification of acrylic copolymers containing free carboxylic acid groups. Biocides chosen are tertiary ammonium salts; alkyl chain substituents with different length are considered. The chemical modifications of resins are carried out via a single step reaction. Modification extents are monitored through proton nuclear magnetic resonance and thermogravimetric analysis and the modified resins are characterised by Fourier transform infrared spectroscopy. The glass transition temperature of the acrylate systems is assessed by dynamical mechanical analysis (pin point method) and compared with data obtained by differential scanning calorimetry. The erosion and antifouling properties of the binders are followed during an exposure to marine environment by a visual observation.     

Ultrathin polymer coatings by complexation of polyelectrolytes at interfaces: suitable materials,structure and properties

The article presents the state‐of‐the‐art of alternating physisorption of oppositely charged polyelectrolytes, the so‐called “layer‐by‐layer” method or “electrostatic self‐assembly” (ESA), for the preparation of thin polymer coatings. In comparison to other, more established self‐organization techniques, this recent method is distinguished by its simplicity, versatility, and speed. In particular, the tendency for self‐healing is unique. Emphasis is given to the role of the molecular structure of the polyelectrolytes, and to the nature of the support. Also, various parameters for the preparation of multilayer films are highlighted, which are very important due to the kinetic control of the build‐up process. The structure of the resulting coatings, their quality and stability, chemical reactions in the films, and potential applications are discussed.     

化学沉积Ni-P-Al2O3和Ni-P-SiC复合材料的微观组织与物理性能

采用化学沉积方法,可以制备以镍磷合金为基质的复合硬质相粒子的复合材料［１］．镍磷合金颇受青睐之处在于可以调整成分和时效处理温度来改变其组织结构,进而获得广泛变化的性能［２,３］．本文报道化学沉积获得的ＮｉＰ氧化铝和ＮｉＰ碳化硅复合材料的微观组织与...     

Crack‐free sol‐gel coatings for protection of AA1050 aluminium alloy

Organically modified sol‐gel coatings have been investigated as potential replacements for chromate conversion treatments of an AA1050 aluminium alloy. The coatings were prepared by combination of a completely hydrolysable precursor of tetra‐n‐propoxyzirconium (TPOZ), with a partially hydrolysable precursor of glycidoxypropyltrimethoxysilane (GPTMS). GPTMS contains an organic functional group, which is retained in the sol‐gel coatings after the hydrolysis–condensation process. Different GPTMS/TPOZ ratios and withdrawal speeds were studied. Coatings produced using a low GPTMS/TPOZ ratio and a high withdrawal speed generated significant cracks due to the shrinkage of the coatings, with no corrosion protection of the alloy. It was found that increase of organic moieties reduced the shrinkage of the coatings and the tendency for crack formation. By control of process parameters and ratios of organic and inorganic moieties, crack‐free sol‐gel coatings above 1 µm thick, with improved corrosion protection, can be produced on the alloy surface. Copyright © 2010 John Wiley & Sons, Ltd.     

Atomic force microscopy of coated glasses

Atomic force microscopy has been used to investigate the topology of alkoxide gel dip coatings on different substrates. Results of SiO(2) - TiO(2) - ZrO(2) (STZ) coatings are presented on float glass, on polished fused silica, on commercially coated insulating flat glass, and on PtRh. Consolidated STZ coatings display the so-called glass pattern with ripples equal or less than 2 nm high. The same pattern is seen on partially dense STZ coatings, as soon as the surface is stiff enough for scanning, and also on the bottom of a 50 nm deep sputtering crater in the consolidated coating. The vitreous STZ coating on the fire side of the float glass is as flat as the float glass itself. It has the same tendency to contamination. 100 nm wide and 50 nm deep polishing grooves on fused silica have been filled up with the 80 nm thick coating, only dips of a few nm remain. The trenches between the SnO(2) crystallites on the insulating flat glass were filled up and the roughness of the substrate was partially reduced. PtRh sheet remained rough even after the coating. On the partially densified STZ coating, sputtering generates a grained surface.     

Cerium hybrid silica coatings on stainless steel AISI 304 substrate

AISI 304 Stainless Steel is widely used in different industrial fields because of its mechanical and corrosion properties. However, its tendency to corrosion in presence of halide ions limits the applications. One strategy to improve the corrosion resistance is the use of coatings barriers containing corrosion inhibitors in their formulation. The lanthanides present attractive green and corrosion properties for the substitution of chromates, which are the most common substances used as corrosion protection. However, these compounds are highly toxic, and an intense effort is being undertaken to replace them. Cerium is a good alternative because of its relatively low cost and abundance. It fulfils the basics requirements for being considered an alternative inhibitor: the ions form insoluble hydroxides and they present low toxicity. Inorganic and hybrid sol-gel coatings have been developed to increase the corrosion resistance of metals and they provide an excellent vehicle for the incorporation of secondary phases including particles and metal ions as cerium ions. The aim of this work was to study the influence of the incorporation of cerium ions in hybrid silica sol-gel coatings deposited on AISI 304 stainless steel as substrate as a potential replacement of chromate treatments. This system should combine the barrier protection effect of silica coating with the corrosion inhibitor effect of the cerium ions inside the coatings. After 7 days of immersion in NaCl, coated substrates showed lower current densities than the bare steel, although the coatings produced from Ce (III) salts experience a slight weakening in time and those obtained from Ce (IV) chemicals evidence an enhance in the coating performance, probably due to the plugging of corrosion products in the defective areas of the film.     

Influence of surface-energy components of Ni-P-TiO2-PTFE nanocomposite coatings on bacterial adhesion

The influence of total surface energy on bacterial adhesion has been investigated intensively with the frequent conclusion that bacterial adhesion is less on low-energy surfaces. However, there are also a number of contrary findings that high-energy surfaces have a smaller biofouling tendency. Recently, it was found that the CQ ratio, which is defined as the ratio of Lifshitz-van der Waals (LW) apolar to electron donor surface-energy components of substrates, has a strong correlation to bacterial adhesion. However, the electron donor surface-energy components of substrates varied over only a very limited range. In this article, a series of Ni-P-TiO(2)-PTFE nanocomposite coatings with wide range of surface-energy components were prepared using an electroless plating technique. The bacterial adhesion and removal on the coatings were evaluated with different bacteria under both static and flow conditions. The experimental results demonstrated that there was a strong correlation between bacterial attachment (or removal) and the CQ ratio. The coatings with the lowest CQ ratio had the lowest bacterial adhesion or the highest bacterial removal, which was explained using the extented DLVO theory.     

Curing processes in solvent-borne alkyd coatings with different drier combinations

The concern regarding the effect of chemicals on the environment has increased considerably in recent years. Nowadays, technological developments in the coating industry are largely influenced by environmental issues and subsequent legislation. One of these issues is the tendency to replace cobalt as a catalyst with more environmentally friendly alternatives, because studies have indicated possible carcinogenicity. Not much knowledge is available on the effects of catalysts (driers) on the in-depth drying of alkyd coatings. Therefore we have studied the effect of cobalt as a primary drier combined with Ca and Zr as secondary driers on the in-depth curing of high solid solvent-borne alkyds. The profiling of the curing of alkyd coatings is performed with a new high-spatial-resolution NMR setup. In this study, two effects observed in the solvent-borne alkyd coatings are investigated. One is that when Ca and Zr are added as secondary driers the speed of the observed cross-linking front increases. Second, in the deeper un-cross-linked region below the front, the signal of the NMR profiles was found to decrease proportional to . This could be explained by the presence of slowly reacting species that diffuse into the deeper uncured region of the coating, after which they cross-link. The model describing the effect of these reactive species also indicates that the signal decrease is inversely proportional to coating thickness L, which was confirmed by additional measurements.     

Atomic force microscopy of coated glasses

Atomic force microscopy has been used to investigate the topology of alkoxide gel dip coatings on different substrates. Results of SiO₂ – TiO₂ – ZrO₂ (STZ) coatings are presented on float glass, on polished fused silica, on commercially coated insulating flat glass, and on PtRh.· Consolidated STZ coatings display the so-called glass pattern with ripples equal or less than 2 nm high. The same pattern is seen on partially dense STZ coatings, as soon as the surface is stiff enough for scanning, and also on the bottom of a 50 nm deep sputtering crater in the consolidated coating.· The vitreous STZ coating on the fire side of the float glass is as flat as the float glass itself. It has the same tendency to contamination. 100 nm wide and 50 nm deep polishing grooves on fused silica have been filled up with the 80 nm thick coating, only dips of a few nm remain. The trenches between the SnO₂ crystallites on the insulating flat glass were filled up and the roughness of the substrate was partially reduced. PtRh sheet remained rough even after the coating.· On the partially densified STZ coating, sputtering generates a grained surface.     

Carrier gas UV laser ablation sensitizers for photopolymerized thin films

Designed carrier gas UV laser ablation sensitizers were synthesized and proved to greatly enhance the UV laser ablation of photopolymerized thin films. Polymers containing dense ester groups are reported to have better laser ablation performance because of the tendency of the ester groups to decompose into gaseous products (“carrier gases”) during the ablation process. In order to introduce this mechanism to cationic UV curable coatings for better laser ablation, a series of “carrier gas” sensitizers were synthesized by reacting hydroxyl containing reactive diluents such as oxetane and polyester polyols with monomethyl oxalyl chloride or dimethyl oxalate; the oxalyl group is considered a “carrier gas” generating moiety. Furthermore, a UV absorbing chromophore, naphthalene, is either chemically bound to the oxalyl containing molecules or blended with the synthesized oxalyl containing compounds to produce a synergistic effect. The “carrier gas” sensitizers were added into a typical cationic UV curable formulation to form sensitized coatings, which were then characterized by thermogravimetric analysis, real time FTIR and ablated by a 355 nm laser. The ablation vias were examined using optical profilometry and SEM. Compared to the control, the sensitized coatings were found to have similar thermal decomposition temperatures and higher functional group conversion during photopolymerization. All of the sensitized coatings containing the “carrier gas” sensitizers exhibited better UV laser ablation performance than the control. The combination of naphthalene derivatives and the oxalyl group gave a better ablation result, suggesting a synergistic effect. The chemical combination of the naphthalene and oxalyl group exhibited better ablation sensitization than their blends, suggesting a more efficient intramolecular laser energy utilization process.     

自由体积与亲水性对环氧涂层防护性能的影响

报道了涂层聚合物自由体积和亲水性对涂层腐蚀防护性能影响的初步研究结果.实验表明,相对于自由体积,树脂的亲水性是决定树脂吸水率的更主要因素.低亲水性涂层腐蚀防护性能的提高主要源自到达涂层/金属界面的水量的显著降低.但由于采用活性酯固化的环氧树脂涂层中水通道的尺寸相对较大,水合离子扩散较容易,因此该类涂层覆盖下的金属基体被润湿部分的腐蚀趋势反而较一般涂层为大.     

Structure of rhenium coatings obtained by CVD

By chemical vapor deposition in the hydrogen atmosphere from Re₂(CO)₁₀ and Re(CO)₃(Cp) on steel and ceramic (C/SiC) substrates, rhenium coatings are obtained with an average thickness of 3–13 μm, when Re₂(CO)₁₀ is used, and of 2–8 μm when depositing from Re(CO)₃(Cp). The coatings are studied by X-ray diffraction and scanning electron microscopy. It is shown that when Re₂(CO)₁₀ is used, an increase in the deposition temperature results in the growth of textured coatings with preferred orientation of crystallites in the [0 0 2] direction. At the same time, a tendency for decreasing the size of rhenium crystallites is observed. With the change of evaporator temperature, the structure of Re coatings obtained from Re(CO)₃(Cp) on steel substrates changes considerably: from compact non-layered without the obvious growth direction (T _evaporator = 120°C) to a three-layer structure, where the initial layer has a compact structure followed by columnar and powdered layers (T _evaporator = 110°C). A fine compact coating is formed on ceramic substrates at an evaporator temperature of 110°C.     

Physico-chemical mechanisms governing the adherence of starch granules on materials with different hydrophobicities

The factors influencing the adherence of starch were examined to improve the understanding of the mechanisms affecting soiling and cleanability. Therefore an aqueous suspension of starch granules was sprayed on four model substrates (glass, stainless steel, polystyrene and PTFE) and dried, and the substrates were cleaned using a radial-flow cell. The morphology of the soiled surfaces and the substrate chemical composition were also characterized. By influencing droplet spreading and competition between granule-substrate and granule-granule interfaces regarding the action of capillary forces, substrate wettability affected the shape and compactness of the adhering aggregates, the efficiency of shear forces upon cleaning, and finally the adherence of soiling particles. The rate of drying had an influence explained by the duration left to capillary forces for acting. X-ray photoelectron spectroscopy demonstrated the presence of macromolecules, mainly polysaccharides, which were adsorbed from the liquid phase, or carried by the retracting water film and deposited at the granule-substrate interface. These macromolecules acted as an adhesive joint, the properties of which seemed to be influenced by the detailed history of drying and subsequent exposure to humidity. In summary, the substrate surface energy affects the adherence of starch aggregates by different mechanisms which are all linked together: suspension droplet spreading, action of capillary forces, direct interaction with starch particles and interfacial macromolecules.     

Trace analysis of halocarbons in water; Direct aqueous injection with electron capture detection

Interest in monitoring halogenated organics in drinking water and natural surface and ground water in the low ppb range continues to grow. There is a tendency to include still more volatile halocarbons, the trace determination of which is known to be rather demanding. This prompted us to re-examine the feasibility of large-volume direct aqueous injection onto capillary columns, coupled with ECD. A primary problem was to avoid simultaneous elution of water with halocarbons, since water suppresses the ground current of the ECD. The following measures contributed to the solution of this problem. Apolar, extremely inert, columns are required to elute water completely, and even before very light halocarbons. Their coatings have to be far thicker (≈? 5 mUm) than commonly employed thick films since they must permit isothermal analysis at a column temperature around 100°C in order to ensure rapid and complete elution of water. Finally, it is essential that sampling be carried out on-column for two reasons: diffusion of water vapor in the injector, resulting in delayed elution, is then eliminated, and peak distortion during splitless injection is avoided. Although we now know that persilylated columns with immobilized coatings withstand routine water injections, more longterm experience is needed to provide detailed recommendations for the handling of these columns.     

Inorganic–organic sol gel hybrid coatings for corrosion protection of metals

Inorganic–organic hybrid coatings by sol–gel process are very suitable for fighting corrosion. Inorganic sols in hybrid coatings not only increase adhesion by forming chemical bonds between metals and hybrid coatings, but also improve comprehensive performances of polymer in the coatings. Different organic polymers or organic functionalities are introduced into gel network to achieve tailored properties, such as hydrophobic properties, increasing cross-linking density, etc. As for corrosion protection of metals organic components of hybrid coatings are selected to repel water and form dense thick films and reduce coating porosity. The factors, such as the ratio of inorganic and organic components, cure temperature, pigments in hybrid coatings, need to be optimized for attaining hybrid films with the maximum corrosion resistance. Electro-deposition technique offers relatively thick homogeneous defect-free hybrid coatings in comparison to dip or spin coating techniques. Green cerium ions and non-ionizable organic inhibitors are more developed in hybrid coatings nowadays than other corrosion inhibitors. Long-term corrosion resistance techniques of inhibitors are discussed. The inhibitors entrapped in the nanocontainers are doped in hybrid films to prolong release of the inhibitors to damaged zones, which is discussed in detail. Among all the nanocontainers of corrosion inhibitors the prospective techniques which show superior corrosion protection are cyclodextrin/organic inhibitor inclusion complexes and layer by layer assembly of organic corrosion inhibitors in nanocontainers. Super-hydrophobic property of hybrid coatings derives from low surface tension and surface roughness of hybrid coatings, which endues the films with excellent corrosion protection for metals, but the durable property of super-hydrophobic coatings needs to be improved for industrial application. An ideal multiple model of hybrid coatings for superior anti-corrosion of metals proposed is a combination of super-hydrophobic hybrid coatings and underlying hybrid coatings doped with sustained release of corrosion inhibitors on metal substrates.     

水性防污涂料的研究进展

海洋污损生物是海洋资源开发首先要面对的问题。防污涂料是防除海洋污损生物的关键材料。传统的防污涂料虽然发展成熟,但以油性溶剂为介质,存在挥发性有机物(VOC)排放过高、环境污染严重的问题。不释放VOC的水性涂料符合绿色无污染的环保要求,是防污材料领域研究的热点。本文对最重要的四种水性防污涂料(污损释放型水性低表面能防污涂料、自抛光型水性防污涂料、污损阻抗型水凝胶海洋防污涂料、强碱释放型水性硅酸盐防污涂料)从防污机理、制备方法和存在的问题等几个方面进行了综述,并对水性防污涂料的发展趋势进行了展望。