Studies on low temperature curable powder coatings

The cure temperatures necessary to affect the flow and subsequent crosslinking of powder coatings has traditionally limited the substrates and thus market applications of these coating systems. This paper will discuss model studies aimed at better understanding some of the cure processes involved in the crosslinking of blocked isocyanate systems. Work done to take the learnings from these model studies and apply them to the development of fully formulated, low temperature curable powder coatings will also be discussed. By considering both the crosslinker and the nature of the polymeric resin it was possible to develop systems that cure at 129–140 °C and have excellent flow and levelling characteristics.     

示温粉末涂料的研究

介绍示温粉末涂料的示温原理、组成、生产工艺及树脂、填料对示温粉末性能的影响。     

UV curable EA-Si hybrid coatings prepared by combination of radical and cationic photopolymerization

A series of UV curable EA-Si hybrid coatings were prepared by a simple approach combining radical and cationic photopolymerization, with epoxy acrylate (EA) as monomer, γ-glycidoxypropyltrimethoxysilane (GPTMS) as inorganic precursor, benzophenone (BP) as free radical photo initiator and a diaryliodonium salt DPIHFP as cationic photo initiator. The chemical structures of EA-Si hybrid coatings were characterized by Fourier transform infrared (FTIR), Raman spectroscopy and X-ray diffraction (XRD). The thermal and optical properties of hybrid coatings were investigated by thermal gravimetric analysis (TGA) and UV–vis transmission spectroscopy, respectively. The results indicated that cross-linked network structure of SiOSi formed in the hybrid coatings, which led to the decrease in crystallinity and of EA-Si hybrid coating. The final conversion of CC bonds was also decreased because of the addition of GPTMS. The thermal stability of EA-Si hybrid coatings was enhanced in the second decomposition stage (300–400 °C) because of the existence of organic–inorganic cross-linked network structures. The transparency of coatings at around 346 nm tended to increase with increasing concentration of inorganic precursor GPTMS.     

Synthesis of fluorinated/methacrylated epoxy based oligomers and investigation of its performance in the UV curable hybrid coatings

Organic–inorganic hybrid coatings based on fluorinated/methacrylated soybean oil and bisphenol A/F epoxy methacrylate were obtained by combining photopolymerization and sol–gel process. Hard and transparent hybrid coatings were prepared on polycarbonate panels and their physical and mechanical properties such as gel content, hardness, adhesion, gloss, contact angle as well as tensile strength were measured. Results from the mechanical measurements showed that the properties of hybrid coatings improved with the increase in fluorine and sol–gel precursor contents. Thermo gravimetric analysis results demonstrated that fluorine and silica incorporations significantly enhanced the thermal oxidative stability of the hybrid coating materials. The surface morphology was also characterized by scanning electron microscopy (SEM). SEM studies indicated that inorganic particles were dispersed homogenously throughout the organic matrix.     

低温环氧地坪涂料的研制

6101环氧树脂是低分子液体双酚A型环氧树脂,具有稳定的化学性能,黏合力强,收缩率小。以6101环氧树脂为成膜物,配合改性聚酰胺环氧固化剂,制得地坪涂料。涂料在低温下有良好的固化性能,可以正常施工,且原料成本相对较低。     

高温液相还原法制备超细钴粉末

利用高温液相二醇还原法,在两种表面活性剂存在下制备出磁性钴的超细粉末。利用X射线衍射、X射线光电子能谱、扫描电镜和激光光散射仪等对所制备的超细钴粉末结构、价态、颗粒尺寸分别进行了表征分析,结果表明该种方法制备的超细钴粉末具有hcp,平均粒径大约为0．4μm。     

绿色太阳热反射涂料降温性能研究

介绍了绿色太阳热反射涂料的制备工艺和颜料配方。与普通外墙用绿色涂料、市售绿色涂料和军用绿色涂料进行比较,研究了自制的绿色太阳热反射涂料的降温性能。结果表明,相对其它涂料,涂覆自制的绿色太阳热反射涂料的涂层其降温效果最好,能使涂覆物的表面温度降低10~15℃,内部温度降低8~10℃;使油罐中油面10 cm处温度下降4~5℃。人工老化实验表明,自制的涂层具有优良的耐候性,适合于户外大型制件的涂饰。     

有机硅树脂在粉末涂料中的改性作用及应用进展

综述了近年来国内外有机硅树脂在粉末涂料中的应用研究进展。讨论了有机硅树脂与有机树脂通过共混、化学结合作为粉末涂料基材以及互为固化剂等不同改性方式的特点。有机硅组分的引入可以改善和提高粉末涂料涂膜性能 ,特别是耐候性及耐热性能。展望了有机硅改性树脂在粉末涂料中的应用和发展前景。     

防锈颜料在粉末涂料中的应用

介绍了防锈颜料及其在粉末涂料中的应用情况。随着新型高效无毒防锈颜料的不断开发,防锈粉末涂料防腐蚀能力迅速提高,其将会获得积极快速的推广应用。     

低温快干环氧煤沥青玻璃鳞片涂料的研制

通过对比实验,确定了能在-5～5℃的温度条件固化成膜的环氧煤沥青玻璃鳞片涂料的配比,讨论了玻璃鳞片对涂膜防腐性能的影响及助剂对涂膜的影响。克服了环氧类涂料在低温条件下固化时间长甚至不能固化的缺点,使环氧煤沥青玻璃鳞片涂料在低温条件下能正常施工。     

Development of low temperature curing, 120°C, durable, corrosion protection powder coatings for temperature sensitive substrates

Commercial low temperature cure powder coatings, including candidates representative of all the major coating chemistries, were evaluated. Nearly all failed to adequately react at a cure schedule of 120°C for 30 min, and none, even when prepared at their manufacturer’s lowest recommended cure conditions, met the stringent performance needs for temperature-sensitive military applications. Initial research is presented toward developing low temperature cure powder coatings that simultaneously meet all performance requirements at this target cure schedule. Using commercial resins, corrosion inhibitors, and catalysts, this research effort has closed gaps in low temperature cure coating performance and has helped to identify critical deficiencies. This study establishes direction for future developments in new resin and catalyst technologies. Presented at the 31 st Annual International Waterborne, High-Solids, and Powder Coatings Symposium, February 18–20, 2004, in New Orleans, LA.     

聚异氰酸酯固化剂在热固性氟粉末涂料中的应用

探讨了聚异氰酸酯固化剂交联反应机理。介绍了热固性氟粉末涂料的制备,分析了选择不同类型的聚异氰酸酯固化剂对热固性氟粉末涂膜性能的影响,从而制得了综合性能优异的热固性氟粉末涂料。     

我国粉末涂料市场现状及发展趋势

1 990～ 2 0 0 2年我国粉末涂料产量年均增长率为 2 4 % ,2 0 0 2年产量为 1 6万t,居世界前列。介绍了我国粉末涂料的生产现状及其在相关行业的应用 ,分析了粉末涂料制造技术与涂装技术今后的发展趋势。指出了粉末涂料行业产品结构调整方向及应重点开发的新品种     

Development of alumina-based hybrid composite coatings for high temperature erosive and corrosive environments

Low alloy steels are being used for structural applications exposed to extreme environmental conditions such as, high temperature, corrosive and erosive environment in petrochemical industry, turbomachinery, chemical reactors, and nuclear industry. These extreme environment conditions severely affect the performance of critical components. In this context, it is attempted to develop the alumina (Al₂O₃) based hybrid composite coatings on ASME SA387-22-2 steel to mitigate the effect of high temperature erosion and corrosion. High-velocity oxygen-fuel (HVOF) thermal spray technique is used to develop the coatings. The physical characteristics of the coatings are recorded in terms of density measurement, thermogravimetric analysis, and surface wettability analysis. Hardness and elastic modulus of the coatings are estimated at room temperature using nanoindentation and microhardness at high temperature (400 °C) using Vickers hardness tests. Metallurgical characterization and eroded surface analysis are done using Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy and X-ray diffraction (XRD). High temperature (400 °C) erosion performance of the coatings is recorded using solid particle Air-jet erosion tester. The Corrosion performance of the coatings are analyzed using the potentiodynamic polarization technique and electrical impedance spectroscopy (EIS). Significant improvement in erosion performance (Erosion reduction: ≈ 96% at 30° and ≈63% at 90°) and corrosion resistance (≈92% reduction in corrosion rate) is recorded for the coating reinforced with 0.8 wt% ceria (CeO₂) and 3 wt% hexagonal boron nitride hBN as compared to the bare steel. The improved erosive and corrosive characteristics of the coatings are attributed to the refined microstructural aspects, in-situ generation of hard second phases, and induction of hydrophobicity in the composite structure.     

Redispersible polymer powder functionalized with NMA and its adhesive properties in dry-mixed coatings

One type of redispersible polymer powder functionalized with N-hydroxymethyl acrylamide (NMA) was developed in this work. The addition of NMA proved to have great influence on the properties of the original emulsion as well as the corresponding powders. The particle size and viscosity of original emulsions both increased with the increasing of NMA amount while the colloidal stability decreased due to the generation of oligomers. However, the fluidity and adhesive performance of the resultant powders were improved obviously by adding more amounts of NMA in polymerization. Taking the above factors into consideration, we found that 3.0?wt.% of total monomers was an acceptable percentage for the NMA to be used. Poly (vinyl alcohol) (PVA) was used as protective colloids in spray drying to prevent the coalescence of emulsion particles so that the reversible dispersion of powders could be realized. The morphology of powder particles was proved to turn into ‘donut’ shape with the increasing of PVA amount, and their reconstitution ability became better. Compared with original emulsion, the reconstituted emulsion had poorer stability and dispersity due to the coalescence of polymer particles in spray drying.     

金红石型钛白粉在水性涂料中应用性能的探讨

从钛白粉的表观指标和应用体系,阐述了钛白粉在水性涂料中的部分应用问题,以及钛白粉的表观指标和应用体系的联系。倡导选择合适的钛白粉品种来设计水性涂料配方。     

甘肃窑街末页岩低温热解的影响因素

为了提高末页岩低温热解效率,以甘肃窑街末页岩为研究对象,采用管式加热炉,研究不同热解终温、终温恒温时间、热载气体流量等热解条件对甘肃窑街末页岩热解产油率的影响。结果表明:末页岩随热解温度升高,产油率先增大后减小,540℃热解产油率达到7.95%;增加终温恒温时间,可提高产油率,恒温时间超过30 min末页岩热解产油率增大不再明显;热载气体流量增大,有利于热载气体对页岩油的携带,载气流量超过300 m L/min热解产油率趋于稳定。最优热解试验条件下原料单独热解的产油率、产水率、产气率比铝甑试验的产率有所提高。     

低温固相反应合成碳酸锶纳米粉体

固相化学反应无污染、工艺简单、操作方便、易于实现工业化生产。应用低温固相化学反应原理，以氯化锶和碳酸铵为原料，经固相反应合成碳酸锶纳米粉体，研究了研磨时间、温度、沉淀剂及表面活性剂对反应的影响。试验结果用XRD与TEM进行表征，证明固相反应进行得很完全，产品为纯碳酸锶，其粒度为50－80nm。