Waxes for powder coatings

Since the first beginnings at the end of the 50^th, the powder coating technology has become a perfected alternative in product and procedure respect to liquid paints. Powder coatings are primarily a mixture of synthetic resins, pigments and additives offering economical and ecological advantages compared to other coating systems. The raw materials are mixed, extruded and ground to coating powders. Waxes play an important part as additives in powder coatings. Production, storage and processing as well as the properties of the applied powder coating can be influenced positively by different waxes. Various waxes and their advantages are demonstrated by practical advantages.     

Tribo charging powder coatings

At present tribo-guns have captured a fairly large market share of the electrostatic spraying equipment used in the powder coating industry for powder paint applications. However, powder paint system based on carboxyl functional polyesters and some special powder paint formulations cannot be sufficiently charged with tribo guns to obtain a good deposition efficiency of the powder on the object. Attempts have been made to solve this problem through addition of special additives to the powder coatings premix or to the ready-to-use powder. Additives of this type have been proven not to be ideal because they can have a catalytic activity and thus effect the powder coatings properties. We developed oligomeric additives that enhance the tribo charging of carboxylic polyester resins based powder coatings, without influencing to the kinetics of the curing process and other properties of the coating.     

紫外光固化粉末涂料

紫外光（UV）固化粉末涂料综合了传统粉末涂料和辐射固化技术诸多优点，是涂料工业的前瞻性产品。本文介绍了紫外光固化粉末涂料的配制，固化机理，涂装工艺及潜在应用，并对其最新研究进展进行了综述。     

Modified ureas: an interesting opportunity to control rheology of liquid coatings

Modified urea compounds can be used as very powerful liquid rheology additives in coatings. Their rheological impact in various coating systems is directly related to the specific chemical modifications that can be made to the polyurea molecule. Modifications evaluated were made using end groups of varying polarities such as low polarity alkyl groups, medium polarity segments, or highly polar structures. Analysis of rheological behavior in various types of coatings indicates the presence of two different thickening mechanisms (H-bonding between urea and urea groups of the additive, and the association of the additive with the binder). These additives result in coatings with exceptional resistance to settling during storage, along with good sag resistance. Some urea type additives used in combination with conventional rheology modifiers such as fumed silicas show synergistic effects. Advantages for coating producers and users will be shown using several practical application examples compared with conventional rheological additives.     

有机硅耐磨透明涂料

详细总结了构成有机硅耐磨涂料的主要原料，无机溶胶添加剂、溶剂及其他助剂，对兼有防雾性、可染色性、抗静电性、紫外吸收性的耐磨涂料进行了介绍，给出了ＪＤ涂覆液的制备及涂层的性能。     

Tailor-made UV-curable powder clear coatings for metal applications

UV-curable powder coatings combine most of the benefits of conventional powder coatings together with the advantages of radiation-curable liquid coatings. This new coating process is not only environmentally friendly. It can also be used to coat substrates like wood, plastic, glass or metal at low temperatures within a short curing time. Several coatings based on binders like urethane vinylethers/unsaturated polyesters or methacrylates are developed for metals, wood or pvc flooring. This paper describes urethane acrylates as a new resin system for UV-curable powder clear coatings. The binders can be amorphous or (semi)crystalline. By combining both types it is possible to get tailor-made binders which exhibit an unique coating performance of excellent adhesion, good flexibility and high hardness on metal substrates. The appearance of the clear coatings can be varied from high to low translucent. In addition, the coatings show a good weatherability.     

Powder coatings for corrosion protection

Powder coatings found a wider use in corrosion protection of steel structure. In Europe very often double-layer systems are used, based on an adhesion promoting epoxy (EP) primer and a weathering stable top coat, mostly polyester (SP) sometimes EP/SP-hybrid powders. An interesting development is the use of zinc filled EP powders as primer to offer a cathodic protection to the steel surface. Powder systems with and without zinc were compared to proved coating systems based on liquid paint materials, where powder coating systems showed results comparable to these systems. Besides many advantages of powder coatings for corrosion protection there are still some problems. The workshops carring out the powder coating have to be in control of the surface pretreatment like chromating, but espescially phosphating and the work with the chromate-free pretreatment methods for galvanized steel. As always in the field of corrosion protection it is the surface pretreatment and preparation which determines the quality of the whole coating system decisively. This problem can be solved by appropriate working. In some years the problem with the general maintenance of powder coatings after weathering and ageing will be actual. This problem should be solved because of the homogeneous coatings on larger areas. Of importance will be the adhesion on the old coating and the appearance of the maintenance coating. The touch up of smaller parts as transport damages will be much more difficult in order to the appearance.     

Comparison of the reactivities of main boron-containing additives used in electrodeposition of nickel-boron coatings

Reactivities of the main boron-containing additives used in electrodeposition of nickel-boron coatings were compared by measuring the rate of boron incorporation into a nickel coating and the effective activation energy.     

Analysis and fate of the hindered amine light stabilizer Tinuvin 622 in polyester powder coatings using high performance liquid chromatography / time of flight mass spectrometry

Hindered amine light stabilizers are used to protect polymers from heat- and light-induced degradation. In this study the oligomeric stabilizer Tinuvin 622 was analysed in-depth employing high performance liquid chromatography/time of flight mass spectrometry (HPLC/TOF-MS) to differentiate products of different manufacturers in respect of their terminating groups and oligomer length. Additionally, the behaviour of the stabilizer in uncured and cured polyester powder coatings was investigated regarding its interaction with the other coating components and chemical changes during the crosslinking process. The extraction efficiency was determined as a function of oligomer length and coating colour.     

Radiation curable materials – principles and new perspectives

Increasing environmental concerns and the ensuing legislation to cut emissions of volatile organic compounds (VOCs) have been major driving forces behind the development of radiation cured coatings over the past 25 years. Today radiation cured coatings are known for their good overall performance and their excellent resistance against chemical and physical surface damages. Advanced photoinitiator systems allow the light stabilisation of UV‐curable formulations and the outdoor application of the coating. The rapid curing, combined with the possibility of immediate processing of the coated objects opens the way for radiation curing – in 100%‐, water based‐, and dual cure systems as well as for radiation curable powder coatings – for a wide variety of application.     

用于水性涂料的Pickering乳液包覆抗蚀活性助剂的研究进展

简述了五种包覆技术和Pickering乳液,综述了Pickering乳液包覆技术制备的复合微球,重点论述了采用Pickering乳液包覆抗蚀性活性助剂的原理以及在水性涂料中的应用,目前研究情况及应用优势,最后展望了Pickering乳液包覆技术的深入研究会对推动水性涂料行业的迅猛发展起到关键性作用。     

碳钢低压冷喷涂铝涂层的海水耐蚀性

本文以Al和10%体积比Al2O3的混合粉末为原料,使用便携式低压冷喷涂设备,在Q235碳钢基体上喷涂了Al涂层. 测试涂层自腐蚀电位及动电位极化曲线,结合扫描电镜观察涂层表面及截面微观形貌,研究了低压冷喷涂Al涂层在海水中电化学腐蚀行为,并与高压冷喷涂和热喷涂铝涂层的耐蚀性比较. 结果表明,低压冷喷涂铝涂层结构较为致密,其耐蚀性比高压冷喷涂铝涂层的略低,而明显优于热喷涂铝涂层.     

Development of hard materials by radiation curing technology

For studying nanoglobular modification effects in radiation cured polymeric composites, we prepared polymerization active silico-organic nanoparticles. With their polymerization active ligands, these nanoparticles form crosslinks by modifying the viscoelastic properties in radiation cured polymeric nanocomposites. In this process, there was a polymerization activity imparted to the particle surfaces of nanopowders, thus applying the physico-chemical modification scheme of a heterogeneous copolymerization to novel scratch and abrasion resistant coatings. By varying the nanoparticle-monomer formulation and the curing method, additional property can be achieved. In this works, we also investigated the influence of various factors such as addition of photoinitiators and other additives into the formulations. The coating materials were applied to the substrate by using different type of coaters. These materials were cured by ultraviolet light and electron beam irradiation. Properties of coatings were characterized using Universal scratch tester and Taber abrasion tester.     

Possibilities of affecting the corrosion-inhibition efficiency of the coatings by means of the zinc powder particle sizes and shapes

The paper deals with morphology and physicochemical aspects of zinc powder concerning the properties of coatings. The sizes or, sooner, the size zinc powder particle distribution manifest themselves especially in the mode of arrangement and affecting the electrochemical mechanism of action in the coating. The lamellar and isometric particle shapes affect by the pigmentation mode and height especially the barrier action and physicomechanical properties of the coating.     

Electrochemical study of the corrosion inhibition ability of “smart” coatings applied on AA2024

Smart epoxy coatings modified with different additives were applied on AA2024. The following three different systems were studied: a reference consisting of an epoxy coating containing chromate active pigments and two “smart” coatings modified with containers loaded with corrosion inhibitor—layered double hydroxides filled with mercaptobenzothiazole and tubular halloysites (HS) filled with 8-hydroxyquinoline. The thickness of the coatings was determined by scanning electron microscopy. The barrier properties and the average corrosion resistance were assessed by electrochemical impedance spectroscopy (EIS). The long-term corrosion repair ability of the various coatings was confirmed by EIS measurements carried for a period of 3 weeks in scratched samples. The ability of the smart additives to inhibit corrosion over defects with different sizes and geometry was studied at the microscale by using localized impedance spectroscopy (LEIS) and the scanning vibrating electrode technique. The results demonstrate that the additives provide effective corrosion inhibition on defects of various sizes. Moreover, the LEIS measurements give some important highlights concerning the mechanisms and kinetics of inhibition of each system.     

HA/CuO/SrCO3梯度复合涂层的制备及体外生物活性

在羟基磷灰石(HA)悬浮液中, 以正丁醇为分散介质, 三乙醇胺为乳化剂, 成骨微量元素化合物CuO 和SrCO₃作为添加剂, Ti片为基材, 壳聚糖(CS)为造孔剂, 依次通过区带电泳分布并在反向电场作用下电 泳沉积, 得到HA/CS/CuO/SrCO₃复合涂层, 经700 ℃高温煅烧2 h后, 制得HA/CuO/SrCO₃复合涂层. 通过X射线衍射(XRD)、 傅里叶变换红外光谱(FTIR)、 场发射扫描电子显微镜(FESEM)、 能量色散光谱仪(EDS)、 劳埃德万能材料试验机、 电化学工作站、 模拟体液培养和抑菌实验等手段对复合涂层进行测试与表征. 结果表明, Ca, Cu和Sr 元素含量在HA/CuO/SrCO₃复合涂层的径向上均呈现梯度分布; 复合涂层与钛基材的结合强度达33.0 MPa; 循环伏安(CV)曲线和Tafel极化曲线测试表明, 复合涂层在N-2-羟乙基哌嗪-N′-2-乙磺酸(HEPES)模拟体液(H-SBF)中电化学性能稳定, 耐腐蚀性较强; 在H-SBF中培养24 d后, 复合涂层表面完全碳磷灰石化; 抑菌实验发现, 复合涂层粉末对大肠杆菌和金黄色葡萄球菌的抑菌率分别为81.82%和71.86%.     

Physical and chemical effects of quartet structure (bamboo / zinc borate / shellac / surfactant) on organic coatings

Bamboo was used owing to its properties as environmentally friendly and lightweight material. The purpose of this study was to increase hydrophobicity, flammability, gloss etc. by using additives (bamboo, shellac, zinc borate and surfactant) with different amounts (0–6%, w/w). Taguchi method was applied to reduce in the number of experiments by carrying out 16 experiments. As a result of the optimization studies, it was seen that the hydrophobicity of the water-based acrylic organic coating has increased from 39.52° (reference coating) up to 104.32° (optimum coating, Exp. No:15, Levels: 4-3-2-4). Shellac increased its homogenization and coating properties with its gloss property. In addition, zinc borate was preferred to increase its properties of flame retardancy, antimicrobial and nonwettable. Surfactant based methacrylate was used for dispersion of coatings. Thermogravimetric Analysis-Differential Thermal Analysis (TG-DTA), Scanning Electron Microscope (SEM), Contact Angle Measurement and physical test (adhesion, gloss, aging) results showed that the additives enhanced the thermal, morphological and physical properties of coatings and it could be evaluated in different areas of the construction industry.     

Electrodeposition of composite Ni–B coatings in a stirred heterogeneous system

The formation of composite electrochemical coatings of a nickel matrix with boron microparticles was investigated. Electrolytical nickel–boron layers were deposited on a paraffin-impregnated graphite electrode in a stirred heterogeneous system formed by a Watts-type nickel plating bath and dispersed boron powder particles. The polarisation behaviour of the composite plating bath as a function of the boron particle loading was examined. The effect of deposition conditions, as well as of the amount of boron powder in the plating bath on the boron content in the composite Ni–B coatings, was examined. The composite coating structure was established using scanning electron microscopy and light optical microscopy. The distribution of boron particles in the composite deposits was investigated by dynamic secondary ion mass spectrometry. The boron particles content was determined gravimetrically. The obtained results suggest that the content of incorporated boron particles increases with an increasing amount of boron in the plating bath. The potentiodynamic deposition method is demonstrated to be more suitable for production of composite coatings with a high content of boron particles than the potentiostatic one. Homogeneous distribution of boron particles in the nickel matrix without coagulation or sedimentation was associated with the electrochemical fabrication method in stirred heterogeneous systems.     

Effect of nitrogen additives on flame retardant action of tributyl phosphate: Phosphorus-nitrogen synergism

The effects of three nitrogen additives (urea, guanidine carbonate, and melamine formaldehyde) on the flame retardant action of cotton cellulose treated with tributyl phosphate (TBP) were investigated in this research. The limiting oxygen index (LOI) of treated cotton cellulose clearly revealed the synergistic interactions of TBP and nitrogen compounds. The Kissinger method was used to evaluate the kinetics of thermal decomposition on treated cellulose. The results show that adding nitrogen additives increases the activation energy at a higher degree of degradation, thus indicating better thermal stability at higher temperatures. Scanning electron microscope pictures of chars formed after a LOI test show the formation of protective polymeric coatings on char surfaces. Evaluating char surfaces using attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggests that these coatings are composed of species containing phosphorus-nitrogen-oxygen. Possible chemical interactions of phosphorus and nitrogen compounds during the burning process and the formation of a protective coating could be the reason for the observed synergism. Potential reaction pathways contributing to the formation of this protective polymeric coating have also been proposed.     

Deposition of protective-decorative coatings onto aluminum alloys

Technique for deposition of a nickel coating onto various aluminum alloys was developed. This coating can be used both independently and as a sublayer under multilayer coatings and, in particular, under those of nickel, tin–bismuth, lustrous nickel, and lustrous chromium. The technique includes anodization, chemical treatment, and electrodeposition of nickel in a special solution. The working modes of the anodization electrolyte were chosen and the necessity for a preliminary chemical treatment of the oxide film being formed was substantiated. A composition of the acid electrolyte for the subsequent nickel plating was developed with buffer and improving additives. The thus deposited electroplated nickel coatings exhibit a high adhesion to the aluminum base without additional thermal treatment. This makes it possible not only to reduce the technological time for deposition of the subsequent multilayer coatings, but also to fully automate the whole process.