Powder coating of veneered particle board surfaces by hot pressing

The powder coating of veneered particle boards by the sequence electrostatic powder application – powder curing via hot pressing is studied in order to create high gloss surfaces. To obtain an appealing aspect, veneer sheets were glued by heat and pressure on top of particle boards and the resulting surfaces were used as carrier substrates for powder coat finishing. Prior to the powder coating, the veneered particle board surfaces were pre-treated by sanding to obtain good uniformity and the boards were stored in a climate chamber at controlled temperature and humidity conditions to adjust an appropriate electrical surface resistance. Characterization of surface texture was done by 3D microscopy. The surface electrical resistance was measured for the six veneers before and after their application on the particle board surface. A transparent powder top-coat was applied electrostatically onto the veneered particle board surface. Curing of the powder was done using a heated press at 130 °C for 8 min and a smooth, glossy coating was obtained on the veneered surfaces. By applying different amounts of powder the coating thickness could be varied and the optimum amount of powder was determined for each veneer type.     

Development of photoluminescent powder coatings by UV curing process

The use of thermal curing powder coatings have obtained a wide acceptance, but is limited to the metal substrates applications, because they need high temperatures for the film curing. Safety sings in edifications use, generally, PVC substrates, that are unable to support typically curing temperatures (150–200 °C). In order to prepare a photoluminescent powder coating by UV curing process, an experimental technique was development and the influence of some preparative conditions were studied. To achieve the better results, photoluminescent pigment percentage, conditions of ultra-centrifugal mill and thickness of deposition coating were varied in order to increase the luminance decay time.     

Si3N4粉体的表面改性及其对立体光刻成型的影响

传统的陶瓷加工技术成本高、周期长、缺陷多,难以生产高性能陶瓷,立体光刻技术是制造形状复杂陶瓷零件的一种高效手段。纯Si₃N₄粉体的折射率(n=2.1)与树脂(n=1.49)的折射率相差较大,光散射严重,导致其陶瓷浆料的固化深度较低,很难直接利用立体光刻技术成型Si₃N₄陶瓷零件。为解决Si₃N₄粉体难以光固化的难题,本研究采用表面包覆有机物和表面氧化两种方式改性Si₃N₄粉体,并对比两种方式对Si₃N₄粉体光固化特性的影响规律。结果表明,包覆实验后,有机物单体经过一定反应时间后可均匀附着在Si₃N₄粉体表面;氧化处理后,Si₃N₄粉体表面形成非晶SiO₂层,该层均匀附着在粉体表面上。原始Si₃N₄粉体的固化深度仅为20 μm,经过包覆改性和800 ℃氧化4 h后,Si₃N₄粉体的固化深度分别可提高到40 μm和50 μm,两种方式均能有效提高原始Si₃N₄粉体的固化深度。     

木质地板用环氧树脂粉末涂料研究进展

对木质地板用环氧树脂粉末涂料的研究进展进行分析。主要从三个研究方向即UV固化环氧粉末涂料、双重固化体系和对传统环氧树脂粉末涂料及其固化剂的改性,对木质地板用环氧粉末涂料低温固化技术进行了探讨。     

Multifunctional NIR-reflective and self-cleaning UV-cured coating for solar cell applications based on cycloaliphatic epoxy resin

We report here a simple, cheap and scale up process for obtaining a multifunctional coating with both, IR reflective and hydrophobic properties. These coatings can be applied on solar devices in order to limit their overheating under operating conditions. The system is based on UV-curable epoxy coating containing IR-reflective fillers and a silicone additive to modify the surface properties with a good hydrophobicity enhancement. The filler dispersion into the epoxy UV-curable resin did not significantly influence the photocuring rate, while a slight decrease of the final epoxy group conversion was evidenced. The optical properties of the obtained coatings have been evaluated by UV–vis–NIR spectroscopy showing that the films act as good “filters” in the NIR region, giving rise to a reduction of the absorbed heat and of the working temperature of the cells. A pronounced increase of hydrophobicity for the films containing the silicone additive was observed. The optical properties were not affected by the addition of the silicone additive.     

PET型光学薄膜用涂层及相关技术研究现状

PET膜以其优异的性能在LCD领域得到了广泛应用,而功能性PET光学膜主要是通过在PET聚酯薄膜表面涂覆各种功能性涂层所得,因此PET型光学薄膜的涂层技术是光学膜的关键技术之一。从光学PET膜用涂层配方、涂层固化方式、涂布工艺和改善膜基材／涂层界面粘接强度的方法等方面,综述了PET型光学膜用涂层技术的国内外研究进展,并提出了未来的发展方向。     

Thermochemical and isoconversional kinetic analysis of a polyester–epoxy hybrid powder coating resin for wood based panel finishing

Powder coating is an established technology especially for the surface finishing of metallic substrates for example in the automotive industry. Moreover, powder technology holds also great promises for the coating of non-conventional substrates like plastics or wood due to the lack of solvents and good recoverability. Here, low-temperature curing resins are required and especially mild processing conditions are demanded by the substrates. Advanced characterization methods need to be established that allow the precise balancing of the processing conditions required for adequate melting, flowing and curing of the powder with the process conditions that can be tolerated by the temperature-sensitive substrates. In the present contribution it is shown that differential scanning calorimetry (DSC) in combination with isoconversional kinetic analysis (ICKA) provides great potential for this purpose. DSC is a standard thermo-chemical method that can be successfully used to study both the melting and curing processes of powder coatings and to determine, for example the glass transition temperature of the cured coating directly from the measured thermograms. However, still more information can be extracted from the enthalpy signals when more sophisticated methods of data post-treatment and analysis are employed. Isoconversional kinetic analysis techniques such as the Kissinger–Akahira–Sunose (KAS) or the advanced Vyazovkin (VA) approaches allow calculating the time-dependencies of physical and chemical processes at various temperatures based on the estimates of activation energies which are obtained from DSC raw data. These analyses allow for example to calculate the time required for a certain degree of cross-linking in the coating after processing the coating under specified curing conditions. In the present contribution the application of ICKA of DSC measurements for the analysis of the flowing and curing behaviour of a powder coating based on a polyester–epoxy hybrid resin is illustrated and the potential of this approach to predict optimal curing times for arbitrary curing temperatures is demonstrated. This is especially useful when temperature-sensitive substrates like wood-based panels are coated. Additionally, the potential to relate the thermo-chemical properties of the powder coating to the surface properties of the coated substrates is discussed.     

Adhesion Improvement of Powder Coating on Medium Density Fibreboard (MDF) by Thermal Pre-treatment

In the powder coating of non-conventional substrates such as engineered wood, natural fibre composites or synthetic polymers, several technological problems must be resolved which result from the substantial differences between such coating substrates and metallic ones. Unlike metals, non-conventional carrier materials show low temperature stability, much rougher and more irregular surface texture, large dependence of their dimensional stability on the moisture content of the surrounding environment and significantly less electrical conductivity. Hence, when powder technology is transferred from coating metals to coating fiberboards, for example, the surfaces of the boards need to be engineered in order to provide ideal adhesion for the coating layer. One major problem is the lack of electrical conductivity. Since the powder coatings are preferably applied using electrostatic spraying equipment, sufficient electrical conductivity of the surface is a major requirement and the correct moisture content plays an important role as well. In the present study, a pre-heating process was used to improve the powder application during powder coating of medium density fibreboards (MDFs). Electrical resistance, treatment temperature and moisture content were systematically studied to better understand the complex physical mechanisms leading to an improvement in powder application by such a pre-heating process. To this end, a new sophisticated procedure was developed to measure the electrical resistance (surface and core resistance) during pre-heating. The results show, that the electrical resistance of MDF is influenced by board temperature and moisture content. Moreover, it is confirmed that pre-heating proves to be an efficient method to improve the powder application onto non-conventional substrates.     

Highly anisotropic thermal conductivity of mesogenic epoxy resin film through orientation control

To develop insulating materials with a high thermally conductive anisotropy, planarly aligned mesogenic epoxy (ME) resin film was fabricated by uniaxial coating on a hydrophobic polyethylene terephthalate substrate. Grazing incidence small-angle X-ray scattering (GISAXS) and transmission SAXS measurements exhibited that the films spontaneously formed uniaxially aligned monodomain-like smectic structures by curing on the hydrophobic substrate. Then, an in- and out-of-plane thermal conductivity of 10 and 0.048 W m⁻¹ K⁻¹ and outstanding thermal conductivity anisotropy of 208 have been confirmed, respectively. The ME resin films with high thermal conductivity can be applied as insulating materials for multiple-layer electrical and electronic devices.     

Development of matte finishes in electrostatic (EFB) and conventional hot dipping (CHDFB) fluidized bed coating process

This study focuses on the correlation between the thermo-rheological properties of a thermosetting powder coating system with its surface structure build-up. Epoxy powder coating systems, which displayed surface matting and surface wrinkling, were examined. Firstly, the evolution of the complex viscosity was correlated with the cure kinetic. Secondly, the structure build-up on the surface of the coatings was investigated with a combined SEM-CLA profilometry analysis at different stages of curing process for both EFB and CHDFB coating processes. Different finishes were found to characterize the films applied by using EFB and CHDFB coating processes as a result of the different way the film is heated by. Finally, a strict relationship of film morphology to the degree of conversion and to the evolution of the complex viscosity was found out for both EFB and CHDFB coating processes. The surface structure is built up after gelation point and continues to evolve after gelation with a full development of the film fine structure. Differences were observed in the surface structure build-up when different curing temperature was used, thereby indicating an influence of minimum viscosity on achievable finishing.     

固化剂对环氧玻璃鳞片涂层性能的影响

以双酚A环氧树脂(E20)为主要成膜物,层片状玻璃鳞片和云母氧化铁为主要填料,辅助以铝粉、氧化铁红颜料,以及各种助剂和溶剂,再分别加入固化剂脂肪族胺加成物、聚酰胺TY-650,制得高固体分厚浆型环氧玻璃鳞片涂料。通过常规的力学性能(涂层的硬度、耐冲击性、柔韧性、附着力等)和耐腐蚀性测试,对比了不同固化剂对环氧玻璃鳞片涂层性能的影响。研究结果表明,脂肪族胺加成物与环氧树脂交联固化的玻璃鳞片涂层的硬度、附着力以及交流阻抗值都较高,具有良好的综合性能,加入铝粉对基体可起到阴极保护作用。     

裂纹涂饰在家具表面装饰中的应用研究

在一定的环境条件下,对中密度纤维板表面砂光处理后,进行裂纹涂饰工艺试验,然后测定涂膜表面的光泽、硬度、附着力、耐黄变性和手感等。结果表明:中密度纤维板家具表面裂纹涂饰工艺可行,漆膜表面附着力、硬度略差,但均符合国家和企业标准。裂纹涂饰的经济成本相对较高,施工难度较大,龟裂状花纹具有视觉冲击力,环保性相对较好,成本相对传统色漆涂饰等较高,作业难度较大。     

Influence of MA‐g‐HDPE compatibilizer content on quality and adhesion/bending strength of polyethylene/O‐MMT coating films

High density polyethylene/organo‐modified montmorillonite composites whit various concentrations of maleic anhydride grafted high density polyethylene (MA‐g‐HDPE) as compatibilizer (5–20 wt %) have been prepared by melt process. The extruded composite powders are applied on the treated steel surfaces using spray electrostatic powder technique, followed by oven curing at various temperatures (180°C–220°C) and times (15–45 min). The surface uniformity of produced coating films is studied by scanning electron microscopy. Comparison of micrographs of the coatings shows the composite coating films are measured using standard methods. The uniformity, adhesion, and bending strength of the coating films are compared to select high performance coatings. The results indicate that the presence of 15 wt % MA‐g‐HDPE in the coatings shows the highest properties (adhesion and bending strength) and more surface uniformity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40926.     

Effect of acid groups in hydroxyl functional resins on the properties of polyester-urethane powder coatings

The concept of using hyperbranched polymers as scaffolds for solid thermoset resin applications is de-scribed. A series of semi-crystalline methacrylae-functional aliphaic poly-esters has been synthesized and characterized for applications as solid thermoset resins, e.g., powder coating resins. The polyester resin have been croslinked by UV irradiation producing either amorphous or semi-crystalline crosslinked films depending on the initial structure. The esins are based on hyperbranced aliphatic polyesters onto which crystaline linear aliphatic polyester chains have been grafted and end-capped with methacrylate moieties. The resins exhibit a rheological behavior suitable for low temperature curing powder coaings, i.e., films that can be readily formed and UV cured a temperatures below 80 °C. 2000 Lake Park Drive Smyrna GA 30080 E-Mails: bin.wu@ucb-group.com and sanilay.padaki@ucb-group.com     

纯环氧型钢筋粉末涂料的研制

采用环氧当量在845~900之间的二步法双酚A型环氧树脂同酚类固化剂搭配作为成膜主体,研究了固化剂、固化促进剂及填料用量对涂层综合性能的影响,优化了配方,制得了性能优异的纯环氧型钢筋粉末涂料产品,可满足当前国内建筑行业用环氧树脂涂层钢筋的各项性能要求。     

湿膜压纹工艺技术的应用

湿膜压纹工艺是指载有无溶剂粘稠状的树脂涂料的基材在包覆成型模具时,涂料与模具的微细图案面接触,复制模具图案,同时施以光固化、电子辐射等固化手段,使涂层瞬间固化,并保持模具微细图案的形状,逐渐从模具上剥离,制得表面附有特殊图案的涂层产品的工艺过程。湿膜压纹工艺在显示器用功能薄膜、电子产品装饰膜(IML)、皮革离型纸、LED照明用增光板等产品的生产中起着重要作用。当今显示行业、IML行业市场、人造皮革花型复型性要求提高、低能耗LED照明产品逐步普及,湿膜压纹工艺的应用领域也日益扩大。本文将着重介绍湿膜压纹工艺中软模与硬模的工艺特点、关键技术以及其应用于增亮膜(棱镜膜)、微棱镜膜、防眩膜生产的最新进展。     

Performance and mechanism of action of self-priming organic coating on oxide covered steel surface

Performance and mechanism of action of a self-priming organic coating formulated by incorporating a linear vinyl terpolymer with appended hydroxyl, acetyl and formal groups, a short oil alkyd resin, alkoxy amino resin cross linkers, extenders and pigments, applied on abraded rust free and rust covered steel surfaces are discussed. During the period of test (4400 h, exposed in 3.5% sodium chloride) it was observed that the coating maintained polarization resistance in the range of giga ohms. Under all conditions of tests, it was noted that the coating applied on steel surface covered with rust performed superior than applied on abraded rust free surface. The studies reveal that phosphoric acid added in coating during its preparation reacts with poly vinyl alcohol to form ester. The ester is diffused to rust present on steel substrate during exposure of coated surface in aqueous environment and transforms originally present mixed phases of rust into a stable phase of maghemite. This transformed layer of rust adheres strongly with O–P–O bond available in binder of coating and forms a passive film resulting in its improved performance.     

核电厂用耐辐射涂料的制备与性能

用环氧树脂、耐辐射颜填料和自制胺固化剂制备出核电厂用耐辐射涂料,采用扫描电子显微镜、差示扫描量热仪对漆膜辐照前后进行了表征。结果显示,辐照试验对漆膜有一定程度的破坏,表现为Tg明显降低;颜填料影响漆膜的去污性能,片状填料如绢云母粉能增加漆膜的抗渗性和耐湿热性;颜基比和施工方式也对漆膜的防腐性能有较大影响。     

聚酯树脂粉末涂料的固化行为

用差示扫描量热法(DSC)对固态条件下聚酯/TGIC(triglycidyl isocyanurate)体系的非等温固化反应动力学进行了研究。根据DSC和热重（TG）的分析结果,对聚酯粉末的固化过程及热稳定性进行了探讨,通过温度-升温速率图外推法确定了该体系的凝胶温度、固化温度和后固化温度分别为113、146和195℃。采用Kissinger方程、Doyle-Ozawa方程和Crane方程对DSC数据进行分析,得到了固化反应的平均表观活化能65.71 kJ·mol^-1,频率因子8.50×106 min^-1、反应级数0.95,建立了该树脂体系的固化动力学模型。讨论了固化反应速率、固化度、固化温度与时间等关系的变化规律及影响因素,为优化铝型材用粉末涂料聚酯体系的固化工艺提供了理论基础。     

耐候型聚酯粉末涂料的研究进展

针对户外用粉末涂料的老化,介绍了国内外耐候型聚酯粉末涂料的研究进展。阐述了其目前在树脂合成与改性、固化体系和固化剂选择及添加特殊助剂等方面的发展方向,并简要分析了其抗老化机理。指出作为粉末涂料的主要组成物质,聚酯和固化剂的性能对粉末涂料的耐候性起着至关重要的作用,同时添加纳米粒子改性粉末涂料也是提高其耐候性的一种新型有效的方法。