Dual layer structural thermoplastic polyester powder coating film and its weathering resistance

Micro FTIR analysis was performed to the point with a 50–80 μm spatial resolution to verify the exact structure of a new blend thermoplastic powder coating film. Resistance to certain artificially accelerated conditions and actual outdoor exposure were examined to confirm the performance of the film as a protective coating for use in the telecommunication field. The new blend powder coating film consists of primary polyethylene terephthalate (PET) and secondary polyvinyl butyral (PVB) resins, and has a distinct dual phase structure. Specifically, it forms a continuous PVB phase in a surface layer with a thickness of approximately 100–150 μm. Good corrosion resistance was confirmed in artificially accelerated testing using salt water spray, heat cycle, and accelerated UV tests. Actual outdoor exposure in a metropolitan area (Shinkiba in Tokyo) and a coastal area (Miyake Island) revealed good weathering performance throughout the study period. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Novel coating resins based on polycarbonates and poly(ester-co-carbonate)s made by catalytic chain growth polymerization of epoxides with CO2 and with anhydride/CO2

In this work we describe a possibly new generation of (powder) coating resins of the polycarbonate or poly(ester-co-carbonate) type, synthesized from epoxides like cyclohexene oxide (CHO), anhydrides like phthalic anhydride (PA) and carbon dioxide (CO₂) by chain growth polymerization, catalyzed by a chromium-Salophen complex and using dimethylaminopyridine (DMAP) as a co-catalyst. The molecular structures of the polymers produced were characterized and especially MALDI-ToF-MS yielded important information on the end-groups and other functional groups which are crucial for the curing chemistry of these resins. One special type of copolycarbonate in this study carried pendent vinyl groups, introduced by copolymerization of CHO and CO₂ with 4-vinylcyclohexene oxide (VCHO). This copolycarbonate was first casted from solution, after which the polymer film was successfully cured with a trithiol compound by UV- or thermally induced radical curing chemistry. These cured coatings showed a good acetone resistance (≥75 double rubs) and reversed impact toughness. A powder coating evaluation of this CHO/VCHO-based copolycarbonate showed excellent processability, high pencil hardness (6-8H), value zero in a Gitterschnitt test on aluminum, reasonable appearance in a ‘PCI-smoothness test’ (value 2–3) and good acetone resistance (≥75 double rubs). Most probably due to a too high T_g (85–104 °C) of the cured coating the reverse impact resistance was poor. A similar powder coating evaluation of a poly(ester-co-carbonate) based on CHO, PA and CO₂ showed less promising results due to poor flow properties and foaming above 140 °C.     

Conductive coating films based on low density In2O3 powders and polymer latexes

Several kinds of conductive coating films were prepared from a low-density indium(III) oxide powder (which was employed because it provides a much higher volume for the same weight) and polymer latexes. The low-density In₂O₃, which is an electrically conductive pigment, was prepared by pyrolysis followed by the combustion of water-swellable polymer microspheres imbibed with In(NO₃)₃, the precursor of In₂O₃. Either acrylamide/N,N'-methylenebisacrylamide or poly(vinylalcohol)/glutaricdialdehyde was used to generate spherical hydrogel particles. The polymer latexes with which the In₂O₃ was mixed had a soft core and a hard shell structure to ensure that the coating film has suitable mechanical properties in addition to conductivity. Acrylonitrile/butadiene/styrene copolymer ABS or acrylonitrile/butylacrylate/styrene copolymer ABAS latexes were used as binders for the conductive pigment. The powder coating followed by hot pressing, the water-borne coating consisting of low-density In₂O₃ and polymer latexes followed by curing, or the colloidal dispersion coating was used to deposit flexible conductive coating films on polyester sheets. The conductive pigment density and the polymer latexes' size and flowability are the factors that affect the characteristics of the film. We found that the colloidal suspension coating procedure based on ABAS latexes achieves better electrical and mechanical properties for the coating films. © 1996 John Wiley & Sons, Inc.     

Depth profiling of coil coating using step-scan photoacoustic FTIR

Photoacoustic (PA) Fourier Transform Infrared Spectroscopy (FTIR) has been demonstrated to be very useful in the analysis of molecular distribution and/or degradation in polymeric materials in a non-destructive manner. Step-scan (SS) PA FTIR has been found to be especially suitable to depth profile multi-layered polymer coating/laminate systems. In this current study, the capability of SSPA-FTIR in assessing industrial coil coatings was evaluated. Two multi-layered model coil coating samples were prepared, one had a pigmented Polyvinylidene Fluoride (PVdF) top coat and the other had a clear Polyethylene Terephthalate (PET) laminate film on the surface; both were depth profiled by SSPA-FTIR. The signal magnitude and phase angle were used to obtain a modulation frequency and a phase angle resolved depth profile, respectively. The advantages and disadvantages of the technique were also investigated. Optical microscopy was used to determine the true thicknesses of the PET and PVdF layers from the sample cross-sections. The values were compared with those predicted by SSPA-FTIR. It was found that a precise depth profile was only obtained with the PET sample whereas in the high pigmented coating system, the predicted values were smaller than the true PVdF thickness, possibly due to the high thermal diffusivity of the inorganic pigment.     

Preparation and application of an ultraviolet curable coating containing nanoscale α‐aluminum oxide

This study focuses on the preparation of an organic–inorganic ultraviolet (UV) curable coating containing the nanoscale α‐aluminum oxide (α‐Al₂O₃) powder and UV curable resin. This developed coating can form a protection film on the poly(vinyl chloride) (PVC) plastic tile surface. Thus, the abrasion resistance of the PVC plastic tile surface is improved. Besides, the adhesion between this UV cured film and the PVC plastic tile surface is well. After treatment with the UV curable coating that contains 6 wt % α‐Al₂O₃, the abrasion resistance of the PVC plastic tile surface can be improved up to 57%. From the result of a scanning electron microscopy (SEM) mapping photograph, it shows that the nanoscale α‐Al₂O₃ powder is well dispersed in the cured coating film. Under the wavelength of the visible light in the range of 400–800 nm, the degree of transparency for the coated film on poly(ethylene terephthalate) (PET) sheet is about 82–90%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5747–5752, 2006     

Internal stresses and adhesion of thin silicon oxide coatings on poly(ethylene terephthalate)

The effect of internal stresses on the cohesion and adhesion of a thin silicon oxide (SiO_x) oxygen-barrier coating, evaporated on a poly(ethylene terephthalate) (PET) film substrate was studied. Internal stresses were generated during annealing in the temperature range for recrystallization of the PET,during calendering in a multilayer structure where two SiO_x /PET films were laminated together with a polypropylene film, and during long-term thermal aging below the glass transition temperature of the polymer. The cohesion of the coating and its adhesion to the polymer substrate were derived from fragmentation tests, in which the failure of the oxide coating was analyzed as a function of the applied stress during uniaxial tensile loading of the substrate. The intrinsic coating strength at critical length and the interfacial shear strength were found to be equal to 1350 MPa and 73 MPa, respectively. It was found that none of the thermal treatments investigated altered the interfacial interactions. Rather, these treatments induced shrinkage of the PET substrate, which increased the coating internal compressive stress and the SiO_x /PET interfacial shear strength. A linear relationship between the SiO_x /PET interfacial shear strength and the coating internal stress was determined from a stress transfer analysis. The coefficient of this linear relationship, equal to-1.34 · h _c/l _c, where h _c is coating thickness and l _c is the critical stress transfer length, reproduces the experimental data with good accuracy.     

Structure and mechanical behaviors of thermoplastic polyurethane thin film coated polyamide 6 fibers part II. A solution coating method

Thermoplastic polyurethane thin film (TPU) coated PA6 fibers were prepared by dipping fibers into a TPU solution. The thickness of the thin film coating was 20 μ m. A series of polymer glycols which include polycarbonate, polyether and polyester were used for the preparation of the TPU. Both tensile strength and elongation at break of the TPU coated fibers increased although both magnitudes of the TPUs are much lower than for the original PA6 fibers. Also there was a significant improvement in the abrasion resistance TPU coated PA6 fibers. The PA6 fibers are prone to micro-cracks when under mechanical stress but the TPU thin film coating delayed the formation of the micro-cracks, thereby improving the mechanical properties of PA6 fibers. The theoretical investigation on the effect of interface interaction region using the viscous flow model described could clearly explain the effect of the same on the mechanical performance of TPU coated PA6 fibers.     

超细尼龙粉改性水性PU漆的机械性能与外观

在水性PU漆中添加超细尼龙12(PA12,商品名为Orgasol),可以改善水性PU漆的耐磨、耐擦划和耐污性。添加不同粒径的Orgasol可以获得柔和的砂纹效果,同时也可以改善涂膜的光泽、附着力和颜色。     

In-situ generation and application of nanocomposites on steel surface for anti-corrosion coating

Thin organic coatings directly on steel sheets provide excellent barrier protection in saline environment and meet deformability demands, but fail in providing active corrosion protection. We have put an effort to solve this problem by formulating composite coatings using in-situ generation of metal oxide nanoparticles (NPs) in the polymer matrix. Here we present a new synthesis method of high performance polyetherimide composite with TiO₂, MgO, and Al₂O₃ nanoparticles and their application for anti-corrosion coatings in saline environment. We observed that in-situ synthesis of these metal oxide NPs in the polymer curing process leads to evenly distribution and uniform size of nanoparticles. Thermo-mechanical property was analyzed for these three kinds of free-standing composite film to assess elasto-plastic behaviour and compared to mother polymer film. Results indicated that thermal stability and elastic behaviour of composites film are not affected to the great extent by the presence of NPs. The potentiodynamic and the electrochemical impedance studies on these composite coated steel panels were carried out to identify active–passive behaviour. Results showed active corrosion protection from nanocomposite coating based on TiO₂ and barrier protection was noticed from nanocomposite coating based on MgO and Al₂O₃.     

Coating films prepared by photoreactions of the surface‐modified diamond powder and PET film with a binder agent

The surface‐modified diamond and PET film underwent photopolymerization rapidly with a binder agent to afford coating films of interpenetrating network (IPN) structure. The coating films thus formed exhibit higher tensile strength, thermal stability, and adhesion strength to the PET film. The inert surfaces of pristine diamond (PD) and PET film were modified by different chemicals and procedures to introduce epoxide and methacryloyl groups, respectively, on their surfaces. A coating agent consisting of an epoxide group containing modified diamond (called ED), a binder agent, and photoinitiators was prepared. After applying the coating agent to the substrate (a glass plate or a methacryloyl group containing PET film, MMA‐PET) and degassing under reduced pressure, the thin film of the coating agent was exposed to UV light (λ_max; 365 nm) at room temperature to yield a coating film of IPN‐structure. The tensile strength and thermal properties of the ED‐containing free coating film (called free film) increased with the amount of ED embedded, whereas the strength of the PD‐containing free film decreased with the amount of PD embedded. The adhesion strength of the coating film on the MMA‐PET improved significantly by the free radical polymerization of the methacryloyl groups on the MMA‐PET and the acrylate resin in the binder agent. The surface photoreactions of ED and MMA‐PET with the binder agent were confirmed by modeling. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A novel approach to the preparation of powder coating—Manufacture of polyacrylate powder coatings via one step minisuspension polymerization

A novel method for manufacturing powder coating through one step minisuspension polymerization is described. The conventional production of powder coating includes six steps—synthesizing resins, mixing the raw material, extrusion, cooling, pre-crushing and pulverization. Comparatively, the present method can simplify the complicated processes, reduce equipment and save energy. Before polymerization, the TiO₂ particles were treated with a reactive silane coupling agent 3-methacryloxypropyltrimethoxysilane (MPTMS) to obtain enough compatibility with the monomers. The powder coating was directly synthesized through employing one step minisuspension polymerization in the presence of titanium dioxide white particles. The powder coating was characterized using Fourier transform infrared spectra (FT-IR) and thermogravimetric analysis (TGA). The results show that TiO₂ particles and polymer are successfully linked up via MPTMS in the powder particles. The morphology of powder coatings produced via different methods was observed by scanning electron microscope (SEM). The powder coatings obtained from minisuspension polymerization consist of regular spherical morphology particles with narrow particle size distribution. The powder flowability and surface film smoothness were enhanced compared to the pulverization powder coating.     

环氧涂料与碳纤维复合材料涂覆性能研究

以环氧树脂和聚酰胺为基料,通过添加KH 560改性的纳米SiO₂、SiC微粉、滑石粉和颜料等物质制备了一种适合用于碳纤维复合材料板材涂装的环氧涂料,探讨了聚酰胺与环氧树脂的质量比及改性纳米SiO₂、SiC、滑石粉的添加量对漆膜性能的影响。结果表明:涂料的最佳配方以甲、乙组分总质量计为:聚酰胺与环氧树脂质量比为1∶3,改性纳米SiO₂、SiC微粉、滑石粉填入量分别为1%、6%、8%,按此配方得到的环氧涂料涂覆在活化液处理后的碳纤维板材上,漆膜具有很好的耐酸碱性、耐水性和耐盐雾性,且柔韧性较好,高温处理后漆膜不发生起皱、脱皮等现象,达到了中车涂装的技术标准;环氧涂料和碳纤维板材存在物理和化学等相互作用,且环氧分子聚合过程中产生的内应力较小,因此附着性能优良,适合工业化作业。     

Carbon black self-networking induced co-continuity of immiscible polymer blends

This work aims to clarify the mechanism of nanoparticle-induced co-continuity in immiscible polymer blends. An industrially relevant system, carbon black (CB)-filled acrylonitrile-butadiene-styrene (ABS)/polyamide 6 (PA6) blends, is investigated via scanning electron microscopy, selective extraction tests, dynamic mechanical analysis, and electrical conductivity measurements. The CB particles are found to be preferentially localized in the PA6 phase, and with an increase in CB loading (Φ_CB), the critical volume fraction of PA6 (Φ_PA6) that is essential for building the co-continuous structure decreases. The product of Φ_PA6 and Φ_CB, n, remains constant for the given system, suggesting that there exists an intrinsic cooperative effect between the CB and the CB-localized polymer phase. A further decrease in Φ_PA6 is achieved either by loading CB with a higher self-networking capability or by isothermal post-treatments for sufficient self-agglomeration of the CB clusters. It is demonstrated that, under the direction of CB self-networking, the CB-localized polymer domains tend to fuse together into co-continuous organization with little phase coarsening. Therefore, CB self-assembly not only plays a key role in extending phase co-continuity over a much larger composition range but also acts on stabilizing the co-continuous polymer domains during the melt processing.     

Development of the scratch resistance on acrylic sheet with basic colloidal silica (SiO2)—methyltrimethoxysilane (MTMS) nanocomposite films by sol–gel technique

The formation of scratch‐resistant coating film prepared from colloidal silica and a polysiloxane matrix was investigated. Methyltrimethoxysilane (MTMS) was hydrolysed and mixed with silica sol (SiO₂) at various compositions to form the hybrid hard‐coating nanocomposite film. The hydrolysed MTMS (polysiloxane) acts as the polymeric binder that is covalently linked to the colloidal silica surface and provides adhesion for the scratch resistant coating film to the substrate. The ratio between the polymeric matrix and the SiO₂ nanoparticles was found to play a major role in controlling the coating film appearance and its resistance to scratching. At a SiO₂ content < 30 wt.%, the agglomeration of the hydrolysed polysiloxane was observed and caused the opacity of the coating film. At a SiO₂ content >70 wt.%, there was not enough polysiloxane to act as a binder for the SiO₂, therefore a shrinkage upon solidification of the coating film caused cracking within the nanocomposite film. The optimum ratio was found to be at 40 wt.% ≤SiO₂ ≤60 wt.%, where the films had a transparent, crack free hard coating, with excellent scratch resistance, good adhesion and very good environmental resistance. The nanoindentation revealed that the nanocomposite film, at the optimum loading, possessed a higher strength with a higher SiO₂ loading. Film properties, including hardness, scratch resistance, adhesion and environmental resistance were also examined. The morphology of nanocomposite films was identified by atomic force microscopy (AFM) and scanning electron microscopy (SEM). © 2011 Canadian Society for Chemical Engineering     

Modification of poly(vinyl butyral) coatings using bis-silanes

A commercially available poly(vinyl butyral) (PVB) coating was modified using a combination of 1–10 wt.% bis(trimethoxysilylethyl)benzene and dibutyltin dilaurate as the hydrolysis catalyst. Results of attenuated total reflectance (ATR)–FTIR analysis indicated the modification resulted in a hybrid coating material containing silicate moieties covalently bonded to the PVB polymer chains. Gravimetric analysis indicted the bis-silane addition resulted in a reduction in the diffusion coefficient of the parent coating to 2-chloroethyl ethyl sulfide (2-CEES), dimethyl methylphosphonate (DMMP), diisopropyl methylphosphonate, and methyl salicylate; the most significant reduction was observed for 2-CEES and DMMP at temperatures ≥50 °C. Glass transition temperature, abrasion resistance, tensile strength, and coating hardness were increased upon incorporation of the bis-silane. Despite incorporation of an inorganic component, coating flexibility was retained at low temperature (−15 °C).     

Improving bonding strength between a hydrophilic coating layer and poly(ethylene terephthalate) braid for preparing mechanically stable braid‐reinforced hollow fiber membranes

A braid‐reinforced hollow fiber membrane with mechanically stable coating layer was prepared by coating a blended polymer dope solution on an alkaline‐treated poly(ethylene terephthalate) (PET) braid. The alkaline treatment was carried out to endow the PET braid surface with more polar groups and better hydrophilicity. The results showed that the bonding strength between the hydrophilic coating layer and modified PET braid was about two times as great as that between the coating layer and original PET braid, while the pure water permeability (PWP) of the membrane remained unchanged when the PET braid was simply treated in 3 wt % potassium hydroxide (KOH) solution at 90 °C for 1 h or 1 wt % KOH solution for 6 h. The proposed modification approach proved to be a facile, low‐cost, and effective method to improve bonding strength between the coating layer and the braid, while other properties, such as PWP and morphology of the coating layer, of the braid‐reinforced hollow fiber membranes were not altered, indicating promising potential in membrane engineering. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46104     

The improvement of anticorrosion properties of zinc-rich organic coating by incorporating surface-modified zinc particle

The corrosion behaviors of zinc-rich coating with various zinc contents, ranging from 0 to 60 volume percent, in thin organic coatings (below 5 μm) were characterized by electrochemical impedance spectroscopy (EIS), free corrosion potential (E_corr) measurement and cycle corrosion test (CCT). It was verified that both coatings with 60 volume percent of zinc powder and without zinc powder showed good corrosion resistance mainly due to the cathodic protection and barrier effect, respectively. On the other hand, coatings with an intermediate concentration (10–40 vol.%) of zinc powder was not successful in protecting a steel substrate efficiently. To improve anticorrosion property of zinc-rich coating, the surface modification of zinc particle was carried out with derivatives of phosphoric and phosphonic acid in the aqueous solution. The effects of the surface modification of zinc particle on corrosion resistance of the coating were investigated with scanning vibrating electrode technique (SVET) and X-ray photoelectron spectroscopy (XPS). The best anti-corrosion performance was achieved when the incorporated zinc particle was treated with phosphoric acid 2-ethylhexyl ester and calcium ion simultaneously, which induced the formation of alkyl-phosphate-calcium complex layer of 190 nm in thickness on zinc particles. Corrosion resistance was improved by the decreased zinc activity and the increased compatibility between the formed complex layer on zinc surface and polymer binder matrix.     

Flexible /PET/batio3/ layer–layer composite film with enhanced dielectric properties fabricated by highly loaded /batio3/ coating with acrylic resin as binder

Flexible layer–layer poly(ethylene phthalate) (PET)/BaTiO₃ composite films with enhanced dielectric permittivity were fabricated by spin coating method, consisting of PET substrate film layer and modified BaTiO₃/acrylic resin hybrid coating layer. The thickness of coating layer was less than 3 μm (about 2% of PET film thickness), and therefore, the PET/barium titanate (BT) composite films remained flexible even at high volume fraction of BaTiO₃ fillers. The volume contents of BaTiO₃ were varied from 0 to 80%, and the solid contents of BaTiO₃/acrylic resin were in the range of 51.8–72.9%. Scanning electron microscopy showed strong interaction of finely dispersed BaTiO₃ particles with acrylic resin. Morphological profile also displayed uniform coating layer of modified BaTiO₃/acrylic resin and its strong adhesion with PET film. The dielectric constant of the PET/BaTiO₃ composite films increased by about 26% at 60 vol % BaTiO₃ loading when compared with the pristine PET film, whereas the dielectric loss decreased slightly. In addition, PET‐grafted poly(hydroxylethyl methacrylate) brushes were used as substrate to introduce covalent bonding with the coating layer. Further enhancement of dielectric constant and reduction of dielectric loss were realized when compared with the composite films with bare PET substrate. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42508.     

Resistance of metallic substrates protected by an organic coating containing glass flakes

The resistance against corrosion of an epoxy-polyamine-based coating immersed in a 3 wt.% sodium chloride solution was investigated by electrochemical impedance spectroscopy (EIS). The organic coating contained glass flakes as pigment in order to enhance its barrier characteristics. The data show that this coating is more strongly adhered and exhibits higher protection characteristics when applied onto carbon steel substrates than on galvanized steel. Though the capacitance of the coating (C_C) does not show any appreciable variation with immersion time, the resistance (R_PO) of the film is observed to increase with time upon immersion. The analysis of the data sustains that the organic film behaves as a porous, non-barrier coating. Two time constants are observed even at earlier exposures, and the improved corrosion resistance developed after the coating system was exposed to the test electrolyte is considered to originate from the precipitation of corrosion products within the pores in the film.     

Morphology and mechanical properties of Nylon 6 toughened with waste poly(vinyl butyral) film

Phase morphology and mechanical properties of the blends of Nylon 6 with scrap poly(vinyl butyral) (PVB) film and poly[styrene-block-(ethylene-co-butene)-block-styrene] (SEBS) have been investigated. Scanning electron microscopic photographs revealed that the spherical PVB particles are finely and uniformly dispersed in the Nylon 6 matrix without changing the shape of the particles. The average particle sizes in all over the blend compositions for Nylon 6/PVB were slightly increased with PVB content, but the dispersed phase is tightly adhered to the matrix phase, with PVB content in the range of 20–35 wt % PVB. Elongation at break and notched Izod impact strength of all the blends were enhanced, which implies good interfacial adhesion. The rubberlike PVB film adhering to the Nylon 6 phase is suggested to give an improved impact strength and toughness. In particular, the optimum PVB content for the best impact strength is found to be in the vicinity of 20–35 wt %, and this composition exhibits better moisture resistance than the other blend compositions. All of the blends up to 35 wt % PVB show higher mechanical properties than those of Nylon 6 blended with conventional impact modifier SEBS. Thus, plasticized PVB film, which is recycled from the process of automobile safety glasses, is applicable as an impact modifier or a toughening agent of Nylon 6. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1531–1540, 1998