涂装半自动生产线的应用与改进

通过对涂装半自动生产线上的工艺流程装备进行改进,解决了涂装生产中残留药液渗入管中不析出、螺栓丝部残漆、零件涂装后存放及转运中磕碰划伤等问题一在不影响原涂装线的基础上,增添了静电喷粉装置,达到了既能喷漆又能喷粉的效果,使涂装半自动生产线设施更加完善,涂装质量得到进一步提高,扩大了应用。     

The role of stress and topcoat properties in blistering of coil-coated materials

The effect of topcoat properties on the tendency of painted materials to blistering was studied. Six topcoats were applied on identical panels of hot-dip galvanized steel painted with a polyester primer. The tendency to blistering was assessed under the conditions of permanent condensation in a Q-panel condensation test at 60 °C. Internal tensile stress and stress development in organic coatings during temperature and relative humidity cycling were investigated by the cantilever curvature method. Although blisters originated from the metal/polymer interface, the extent of blistering was strongly influenced by the topcoat. Available data suggest that it may increase with the coating thickness, glass transition temperature (T_g) and thermal expansion properties. Connection was found between the internal tensile stress formed in topcoats during the paint film preparation and the extent of blistering. A hypothesis that stress-assisted interfacial bond hydrolysis was responsible for blister initiation is proposed. Other experiments suggested that local paint buckling over non-adherent sites can be caused by plastic deformation of the paint due to relief of compressive stress generated at elevated temperature or by ingress of water.     

Connection between the deformation of paint droplets during deposition on the surface being painted and the orientation of pigment particles

In this work, we describe a new and more practically useful approach to finding the relationship between the reflective properties of a painted surface, the physical properties of the paint, and the technological parameters of painting. A simple formal dynamic model of the deformation of a droplet of a “metallic”-type paint during its interaction with the surface being painted is constructed. The physical model takes into account the main forces responsible for the deformation dynamics of a droplet, i.e., forces of surface tension, viscous friction, elasticity, and inertia; a new rheological model, which is suitable for approximating the viscosity of paints in a wide range of deformation rates, is used. To construct the mathematical model, we employed the method of integral balance equations of mass, momentum, and energy. The model is used to calculate the most important stages of the deformation of paint droplets during their deposition on the surface being painted, which have an effect on the orientation of pigment particles. For these stages, we compose characteristic strain-approximating functions of the Reynolds and Weber numbers, which are proved to be useful for summarizing the results of experimental studies of the entire real process of painting.     

Optimization of phosphate coating properties on steel sheet for superior paint performance

The adhesion of electrodeposition (ED) paint on steel sheets for automobiles is highly influenced by the properties of the zinc phosphate coating which is used to improve its corrosion resistance. In the present study, a steel surface was pretreated with two types of zinc phosphate formulations followed by ED painting. The surface morphology, crystal plane, and porosity properties of phosphate coating on steel samples were studied by scanning electron microscope, X-ray diffraction, and electron probe microanalyzer, respectively. The corrosion resistance of painted samples was evaluated by an accelerated corrosion test as well as by electrochemical techniques like cathodic disbonding and AC?CDC?CAC tests. The phosphate coating enriched with a phosphophyllite structure showed small globular crystals with less porosity, whereas a hopeite structure showed coarse crystals with high porosity and comparatively thicker coating. The maximum corrosion resistance was observed in the painted sample, where the phosphate coating comprised a phosphophyllite structure. On the other hand, the painted samples phosphated with a predominantly hopeite structure showed inferior corrosion resistance performance. The unphosphated sample showed severe degradation in paint adhesion and corrosion resistance, which substantiates the importance of phosphate pretreatment.     

双组分聚氨酯涂料用改性醇酸树脂的研究

采用不同改性的短油度醇酸树脂作甲组分,异氰酸酯预聚物作乙组分,配制双组分聚氨酯涂料,探讨甲组分对双组分聚氨酯涂料性能的影响。结果表明,椰子油改性短油度醇酸树脂,颜色水白、耐黄变性能和丰满度好,可以作为高档的亮光清面漆、耐黄变的面漆用树脂;蓖麻油改性短油度醇酸树脂,颜色较深、丰满度较好、干燥速度慢及柔韧性好,可以作为普通的亮光面漆用树脂;豆油改性短油度醇酸树脂,干燥速度较快,应用于底漆和哑光面漆;合成脂肪酸改性短油度醇酸树脂,颜色水白、流平好、干燥速度慢、丰满度高及硬度高,可以作为高档的亮光面漆用树脂。     

The effects of thermoplastic poly(olefin) (TPO) morphology on subsequent paintability and thermal shock performance

Adhesion to thermoplastic olefin (TPO) substrates is strongly influenced by the type and amount of solvent contained within paint applied. Morphological changes in the TPO substrate are accomplished in the presence of solvent from the topcoat and vary depending upon paint bake times and temperatures. These morphological changes at and near the surface of TPO affect not only the paint adhesion to the substrate but also the cohesive integrity of the painted plastic composite. This paper attempts to delineate the influence of paint and paint processes on the adhesion/cohesion and mechanical properties of coated TPO parts, in particular, the performance of 2K topcoated TPO substrates under thermal shock conditions. It was found that the most important attribute contributing to thermal shock resistance of painted TPO parts was the bake temperature of the topcoat. A temperature of 250 °F in either the adhesion promoter bake or the topcoat bake is necessary to afford acceptable thermal shock performance. It is postulated that the rearrangement of poly(propylene) crystallites at the uppermost surface of the TPO under a 250 °F bake accounts for the increased cohesive strength of the painted composite.     

Correlating thermodynamic and mechanical adhesion phenomena for thermoplastic polyolefins

Polyolefins are used over a wide range of industries due to their low cost and adaptable mechanical properties. However, their low surface energy makes fabricating composites and applying coatings challenging. Therefore, various surface treatments have been utilized to enhance their adhesion properties. In this paper, the surface energies of various thermoplastic polyolefins (TPO) have been measured via Inverse Gas Chromatography (IGC). These surface energy values were correlated to mechanical adhesion testing of the painted polyolefins. The adhesive integrity of the painted TPO was determined by applying a comprehensive-shear load to the material. Higher surface energies measured by IGC lead to increased adhesion with the paint. The surface energies also correlate with TPO crystallinity, as determined by microhardness testing of the unpainted TPO. Presented at the 2006 FutureCoat! conference, sponsored by the Federation of Societies for Coatings Technology, in New Orleans, LA, on November 1–3, 2006.     

Influence of vehicle on historical pigments colour

The colour of a paint layer is determined by the pigments mixed with a vehicle and painted on a support. According to their chemical nature, the vehicles are substances that, after drying or hardening, produce an uniform and homogeneous layer. With the aim of quantifying the influence of the medium on the specification of the painting colour, we realized samples of paintings. We considered pigments and dyes of the artist's hues using the vehicles typical of ancient times: oils (especially linseed and poppy oils), casein and egg yolk, mixed according to old recipes. Measurements were performed by reflectance spectrophotometry observing the Spectral Reflectance Factor (%SRF) trend and calculating colour changes. The colorimetric study was carried out in the CIELAB colour space related to the CIE 1964 standard observer and with the D65 illuminant. The results were evaluated also on the basis of the distribution of pigment particles on paint layers observed by scanning electron microscopy.     

载货汽车底盘零件涂装工艺探讨

针对国内载货汽车底盘零件涂层存在的防腐性与耐候性不良等问题,介绍并分析了车架、车轮、车桥与钢板弹簧等零件的涂层质量要求、典型涂装工艺特点,提出了涂层质量改善的思路与建议。车架总成电泳涂装应选用兼顾防腐性与耐候性的“底面合一”型阴极电泳涂料,车架纵梁喷粉、零件单独涂装后再进行总成装配可改善缝隙、夹层等部位的锈蚀问题;车轮涂装应保证零件的抛丸质量与电泳漆膜厚度;车桥涂装应关注零件的底漆质量与总成的喷涂质量;钢板弹簧涂装应去除氧化皮,板簧单片进行涂装,装配后再总成喷漆。     

Examination, conservation and restoration of painted art

To conserve or restore painted artwork, it is necessary to appreciate the nature of the basic materials used in its creation, to be able to identify the pigments and the application media that were originally – or have subsequently been – applied and to understand the nature of gradual chemical and physical degradation that occurs within the various components of the system. With information thus gained, one can determine how best a painting may be cleaned, restored and ultimately be better preserved. This review covers the range of analytical techniques (mostly spectrographic), which have often been specifically developed to aid the identification of the wide range of inorganic colours and organic binders (or their degradation products) that may be present in each paint layer of an old masterpiece. Although an art gallery or museum strives to conserve the artefacts it displays, over time there will be varying degrees of mechanical or chemical damage. Cleaning (and, more controversially, restoration work) therefore becomes necessary and the much-improved methods now available for achieving this without associated adverse effects are reviewed.     

Nondestructive analysis of uneven paint coatings by dynamic heat conduction following flash heating

A method of assessing uneven paint coatings is described, wherein a painted surface is rapidly heated by a light flash and the subsequent surface temperature changes are monitored using thermography. This method exploits the differences in dynamic heat transport caused by variations in paint thickness, using thermographic observation to track differences in temperature related to thickness. During trials with intentionally uneven test specimens spray coated with blackbody paint or red, blue, and green acrylic lacquers, we determined that surfaces with thinner paint coatings exhibited lower temperatures. Based on our findings, this article also discusses the theoretical basis of the detection method. While this technique can detect uneven painting, it is difficult to determine a quantitative relationship between temperature variations in the coated surfaces and paint thickness, since the relationship is dependent not only on the particular substrate and paint, but also on the optical reflectance of the paint. We consider that the proposed method is currently capable of detecting uneven paint coatings with variations in thickness of approximately 20 μm, although improvements in detection resolution are possible. Although detection sensitivity is somewhat low, this technique allows rapid analysis of coatings to assess evenness through visual examination.     

Flammability of oil‐based painted gypsum wallboard subjected to fire heat fluxes

The flammability of painted gypsum wallboard (GWB) exposed to fire heat fluxes is investigated. GWB samples coated with multiple layers of alkyd/oil‐based paint are subjected to constant incident heat fluxes of 35, 50 and 75 kW/m² in the Cone Calorimeter for periods of 5, 10 and 15 min. A number of coats of alkyd/oil‐based interior semi‐gloss enamel paint, including 1, 2, 4, 6 and 8 coats, are applied over a single coat of oil‐based primer to the exposed surface of 16 mm (5/8 in.) thick type X GWB. Unpainted type X GWB is also evaluated under the same exposure conditions. The potential for upward flame spread based on the Cone Calorimeter results is evaluated. The occurrence of paint ‘blistering’ is observed to have a significant effect on the time to ignition and consequently on the potential for upward flame spread. Further work is needed to evaluate the conditions under which ‘blistering’ will occur and its effects on the potential for surface flame spread on painted gypsum wallboard. Copyright © 2004 John Wiley & Sons, Ltd.     

Mechanical and barrier properties of cardboard and 3D packaging coated with microfibrillated cellulose

Microfibrillated cellulose (MFC) is increasingly used with cellulosic substrates and especially with paper materials. Its use with cardboard remains not reported and the study of mechanical and barrier properties of MFC‐coated cardboard has been investigated in this article. The influence of coating process as well as the effect of MFC have been highlighted by comparing different MFC‐coated cardboard samples with PE‐coated cardboard samples. MFC was coated using bar coating process. Their distribution and homogeneity onto cardboard was observed using techniques such as SEM and FE‐SEM. Tests such as oxygen and air permeability, bending stiffness, and compressive strength have been carried out. The coating process used impacts significantly cardboard properties by two opposite ways: on one hand it damages the structure cohesion of cardboard decreasing its compressive strength; on the other hand it increases its bending stiffness by increasing considerably the samples thickness. The addition of MFC counterbalances the negative effects of the coating process: bending stiffness and compressive strength are indeed improved by 30% in machine direction. On the contrary, MFC does not enhance much cardboard barrier properties, although it considerably increases their water absorption. Within a framework of packaging application, MFC will rather have consequent effects on cardboard's properties as blend or as part of the multilayer structure. Other applications have to be considered for its use as top layer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40106.     

Studies on surface properties of polymeric coated paper material

Surface properties of a polymeric coating system have a strong influence on its performance and service life. However, the surface of a polymer coating may have different chemical, physical, and mechanical properties from the bulk. Significant progress has been made during the last three decades in the improvement of coating on materials. It has been established that polymeric blends have great potential in replacing economically many conventional materials because of their high specific strength. It is needed today, constantly, to improve the surface finish of any material for efficiency and shiny appearance in the severity of working environment. In packaging, materials having longer service lives and those are less corrosive are highly used. The effect of polymer based coating on the paper material improves its mechanical properties and flame resistance. Effect of flame retardant polymer coating illuminates the surface of the sheet. Important application of the material sheets will be for corrosion receptivity and humidity resistance of this material will certainly improve. Blends of PMM/PVDF are mainly used to improve piezoelectric properties of PVDF. In the present study we report the measurement of surface properties of thin layer of polymer blend coated on the cardboard sheet substrate material. Polymer blend solutions of PMMA/PVDF was prepared at 90/10 (w/w) proportions in miscible solvent of toluene and DMF. Thin film was prepared on the surface of cardboard by dipping the cardboard material in the solution. Thickness of the dried polymer coated paper sheet was measured to see uniformity of coating and for different concentrations. Surface properties such as flexibility index, yellowness, and gloss reflectance were also measured. The study on these polymer coated paper will help in improving the surface property of paper as well as its use in packaging. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4167–4171, 2006     

Quantitative measurement of adhesion between polypropylene blends and paints by tensile mechanical testing

A tensile mechanical test suiable to measure the adhesion between brittle coatings and ductile substrates was applied to measure the adhesion of painted layers on polypropylene blends. The test involves the tensile deformation of the painted assembly, resulting in the periodic cracking of the brittle coating on the ductile substrate. The interfacial shear strength was determined by measuring the strength of the coating, the thickness of the coating, and the average width of paint fragment after the crack density reaches saturation. Apparent interfacial shear strength was obtained for different paints on the same kind of blend, which gave consistent results over the experimental strain rate range from 10^?4 to 10^?3 sec^?1. Interfacial delamination was studied by optical microscopy (OM) and transmission electron microscopy (TEM). The delamination was observed to mainly occur near the adhesion promoter and substrate interface.     

Effects of mechanical properties of paint film on the forming of pre-painted steel sheets

Formability is one of the most important factors for pre-painted steel sheets (PCMs). Both high formability of the steel substrate and high integrity of the paint films on it after processing are required. In this study, elongation, tensile strength and elastic strain energy of various paint films were examined by tensile test, and the relationship between the mechanical properties of paint films and the integrity of paint films of PCM after bending and drawing were studied. We found that the required properties of paint films of PCM depended on the forming mode. In the bending mode, in which steel sheets were mainly subjected to tensile strain, the damage of paint films was dominated by the maximum strain and the tensile strength of the paint films. The paint films having higher maximum strain and higher tensile strength had better formability in bending. On the other hand, the damage of paint films was dominated by the maximum strain of paint films and elastic strain energy stored in paint films after deformation in the drawing mode in which steel sheets were subjected to tensile and compressive strain. The paint films having higher maximum strain and lower elastic strain energy had better formability in drawing. The relationship between the lubrication attributes of paint films and the limit of drawing ratio (LDR) of PCM was also studied. It was observed that the PCM with paint films having low friction coefficient had a higher LDR and it was the same ratio as the unpainted substrates.     

Hybridization effect of cellulose paper and postcuring conditions on the mechanical properties of flax fiber reinforced epoxy biocomposite

An ever-increasing rise in demand for sustainable materials has received significant attention in developing biocomposites for structural applications. In this regard, natural fibers replacing synthetic fibers as reinforcement in epoxy composite could be a significant gain toward sustainability, especially in automobile and structural applications. Herein, flax fiber/cellulose paper–reinforced epoxy biocomposite (FREC-X) was fabricated via a vacuum infusion process. The influence of postcuring conditions (time and temperature) and cellulose paper density on the mechanical properties of FREC-X was studied. The tensile strength and modulus of FREC-X increased by 37% and 64%, respectively, upon the integration of paper. Postcuring FREC-X further augmented the tensile and flexural properties of the composite, which could be attributed to the increase in cross-linking of the epoxy and yields a strong polymer network. Fractography analysis confirmed that the composites integrated with paper showed fewer defects with improved interfacial adhesion. In addition, the water absorption and thickness swelling results revealed that the presence of cellulose paper marginally increased the water uptake and thickness swelling of FREC-X. Furthermore, there was no significant change in the tensile and flexural properties of FREC-X observed even after immersing in water for >200 h. Such properties of FREC-X seen as a fascinating alternative to synthetic fibers and petroleum-based epoxy and are promising material for sustainable development.     

Effect of powder painting procedures on the filiform corrosion of aluminium profiles

In this work, the filiform corrosion behaviour of powder painted aluminium profiles was studied, and the coating barrier properties together with adhesion to the substrate were analysed. Samples coated with a traditional painting procedure (one powder layer application followed by curing), and other samples coated using a special cycle to obtain wood grain effect were compared using accelerated filiform corrosion tests. Moreover, in order to better understand the degradation mechanisms of painted metal substrates, thermal stresses were applied to accelerate the natural weathering. The effects of the thermal aging were analysed by electrochemical impedance spectroscopy.     

Effect of the doses and nature of vegetable oil on carbon black/rubber interactions: Studies on castor oil and other vegetable oils

The effects of additives in various vegetable oils on the physical, mechanical, and adhesion properties of carbon black/rubber compounds were studied. Various doses of castor oil and some other oils such as paraffin oil, vegetable oil 1, and cashew nut shell liquid (CNSL) at a fixed dose (1 phr) were used. With an increase in the castor oil content, the modulus, tear strength, and tensile strength increased, whereas the hardness and adhesive strength exhibited little variation up to 1 phr. Beyond 1 phr castor oil, the modulus, tear strength, and hardness decreased, whereas the adhesive and tensile strengths increased up to 2.5–3 phr and then decreased. Therefore, castor oil seemed to behave as a coupling agent up to 1 phr and as a coupling agent and a plasticizer in the range of 1–3 phr; beyond that, the main role of castor oil was plasticization. When various oils at a fixed dose (1 phr) were compared, it was found that the vegetable oils exhibited enhanced properties in comparison with those of paraffin oil. In addition, both of the unsaturated oils (castor oil and vegetable oil 1) enhanced physical and mechanical properties in comparison with saturated paraffin oil. CNSL exhibited the best adhesion properties against mild steel and galvanized iron substrates. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1574–1578, 2003     

Prediction of spectral reflectance factor distribution of automotive paint finishes

It is necessary to determine the accurate reflectance of painted surfaces for the review of paint finishes by computer graphics (CG) before actual painting of the exterior color of automobiles, and for quality control during production and inspection processes. We have optimized a method for measuring reflectance by using a statistical technique. We have found that the reflectance of a painted surface is best measured at an incident angle of 60° and at five aspecular angles of 10°, 18°, 28°, 40°, and 90°. Our method makes it possible to accurately reproduce reflection characteristics of paint finishes containing special flake pigments, such as pearl mica. Also it was proved that our method can apply not only to solid and metallic coatings but to all painted surfaces. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 275–282, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20125