Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Relating gloss loss to topographical features of a PVDF coating

Semi-gloss commerical poly(vinylidene fluoride) (PVDF) coatings typically have 60° gloss values between 20 and 50. Gloss is affected by PVDF crystallite structures and by the pigmentation. In this article, we have demonstrated that for some pigmented PVDF coatings, after 10 years of Florida exposure, the principal proximal cause of gloss changes is the formation of micron-scale pits, rather than the emergence of pigment particles at the coating surface. We have used laser scanning confocal microscopy (LSCM) and light scattering to characterize the surface topography and near-surface structure of weathered and unweathered PVDF coatings. Florida-weathered PVDF coatings show only a modest increase in the root mean square (RMS) roughness of the surface, even when oticeable gloss loss has occurred. Changes in gloss can be correlated with surface roughness and other topographical, features, including the formation of pits and the emergence of pigments. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 25–27, 2004, in Chicago, IL.     

Inorganic/organic nanocomposite coatings: The next step in coating performance

Inorganic/organic hybrid materials have considerable promise and are beginning to become a major area of research for many coating usages, including abrasion and corrosion resistance. Our primary approach is to prepare the inorganic phase in situ within the film formation process of the organic phase. The inorganic phase is introduced via sol-gel chemistry into a thermosetting organic phase. By this method, the size, periodicity, spatial positioning, and density of the inorganic phase can be controlled. An important aspect of the inorganic/organic hybrid materials is the coupling agent. The initial task of the coupling agent is to provide uniform mixing of the oligomeric organic phase with the sol-gel precursors, which are otherwise immiscible. UV-curable inorganic/organic hybrid systems have the advantages of a rapid cure and the ability to be used on heat sensitive substrates such as molded plastics. Also, it is possible to have better control of the growth of the inorganic phase using UV curing. It is our ultimate goal to completely separate the curing of inorganic and organic phases to gain complete control over the morphology, and hence optimization of “all” the coating properties. Thus far, it has been found that concomitant UV curing of the inorganic and organic phases using titanium sol-gel precursors afforded nanocomposite coatings which completely block the substrate from UV light while maintaining a transparent to visible light. Also, it has been found that the morphology of the inorganic phase is highly dependent on the concentration and reactivity of the coupling agent. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL.     

Advanced techniques for nanocharacterization of polymeric coating surfaces

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. In order to monitor the coating property changes with environmental exposures from the early stages of degradation, nondestructive techniques with the ability to characterize surface properties with micro- to nanoscale spatial resolution are required. In this article, atomic force microscopy has been applied to study surface microstructure and morphological changes during degradation in polymer coatings. Additionally, the use of AFM with a controlled tip-sample environment to study nanochemical heterogeneity and the application of nanoindentation to characterize mechanical properties of coatings surfaces are demonstrated. The results obtained from these nanometer characterization techniques will provide a better understanding of the degradation mechanisms and a fundamental basis for predicting the service life of polymer coatings. Presented at the 81st Annual Meeting of the Federation of Societies for Coatings Technology on November 12–14, 2003, in Philadelphia, PA.     

Two-component high-solid polyurethane coating systems based on soy polyols

Soybean oil based polyols—soybean oil phosphate ester polyols (SOPEPs)—having varying hydroxyl content and viscosity were prepared as low cost and low-VOC polyols for coatings applications. These SOPEPs were used as the hydroxyl component of “two-component polyurethane (2K-PU)” coating compositions and their film properties were studied. Blends of commercial polyester polyol and SOPEP in varying proportions were also used to formulate PU coatings. Their film properties were studied and compared. We found that SOPEP can be used as the sole hydroxyl component or as the reactive diluent for polyester polyols in 2K-PU coating systems. SOPEP, is derived from a relatively inexpensive and renewable resource and the use of SOPEP can substantially reduce VOC and cost of PU coating formulations. Presented at the International Waterborne, High-Solids, and Powder Coatings Symposium, New Orleans, LA, February 2002.     

Waterborne acrylic-epoxy coatings

Waterborne two-component acrylic-epoxy coatings are gaining popularity as topcoats in moderate duty industrial and high performance architectural (HIPAC) applications. This increased popularity is due to their attractive handling, application, and performance properties, along with their low solvent content and odor. The objectives of this work were to characterize the cure and property development of these coatings, evaluate performance properties of cured films, and investigate a new epoxy resin dispersion in existing acrylic-epoxy formulations. These evaluations confirmed that existing acrylic-epoxy coatings have long pot life and short dry times while displaying a range of chemical resistance and physical properties. IR spectroscopy and differential scanning calorimetry (DSC) results indicated that the extent of cure at ambient conditions over a 21-day period was minimal; however, dynamic mechanical analysis (DMA) and solvent swell results did illustrate noticeable crosslink density development under these conditions. DSC results demonstrated more complete reaction and cure after heating. Direct substitution of a novel epoxy resin dispersion into these formulas resulted in lower required solvent content, shorter dry time, higher gloss, higher crosslink density, and improved water and scrub resistance. Presented at the 79th Annual Meeting of the Federation of Societies for Coatings Technology, on November 5–7, 2001, in Atlanta GA. 7201 Hamilton Blvd., MailStop R3108, Allentown, PA 18195-1501.     

Cationic ultraviolet curable coatings from castor oil

Coatings formulated from castor oil glycidyl ether (COGE), epoxy resin UVR 6100, and photoinitiator UVI 6990 produced smooth coatings with excellent gloss and good flexibility, adhesion, gloss retention, and water resistance. Formulations containing up to 50% COGE afforded promising coating performance attributes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 8–13, 2000     

High performance waterborne coatings based on dispersions of a solid epoxy resin and an amine-functional curing agent

A novel, waterborne epoxy system comprised of non-ionic stabilized dispersions of a solid epoxy resin and an amine curing agent has been designed for ambient-cure coatings. The performance characteristics of coatings formulated from the new system have been compared to a standard system. The new system produced formulated coatings with robust performance over a wide range of amine-to-epoxy stoichiometries (65 to 130%). At 100% stoichiometry, the new system was found to have lower VOC, faster hardness development, better gloss, and higher impact resistance than the standard system. The new formulations also exhibited superior water and salt spray resistance, and a definitive viscosity rise at the end of potlife. Unlike the standard system, coating morphology of the new waterborne system was found to be similar to a solvent-based coating. For the new system, good coalescing solvents, as judged by gloss and gloss potlife, were found to have low solubility parameters and high boiling points. Presented at the 76th Annual Meeting of the Federation of Societies for Coatings Technology, on October 15, 1998, in New Orleans, LA. P.O. Box 1380, Houston, TX 77251-1380.     

The influence of ageing of epoxy coatings on adhesion of polyurethane topcoats and protective properties of coating systems

The dependence of adhesion and protective properties of coating systems on surface properties of epoxy intermediate coatings, aged and non-aged before an application of polyurethane topcoats, were examined. The intermediate coatings were aged 500 h in UV chamber. The surface free energy and polar groups were estimated after ageing. After applying polyurethane topcoats on aged and non-aged epoxy coatings, resistance to salt spray and thermal shocks were tested as well as internal stresses were measured before and after corrosion tests.The results showed that adhesion in coating systems with polyurethane topcoats applied on aged epoxy coatings depends strongly on the degradation degree of epoxy intermediate coatings and the value of generated internal stresses. Coatings with good adhesion retention in corrosion environments have good protective properties even when temporary blistering has occurred.     

Novel ambient temperature curable two-component waterborne silicone-acrylic coatings

Waterborne coatings are composed of resins containing hydrophilic functional groups. These groups usually remain in the coating film and can adversely affect film properties such as weatherability and resistance to water and alkali. We have developed a novel ambient temperature curable waterborne two-component system, in which the hydrophilic functional groups are consumed by the crosslinking reaction. The new coating system consists of a waterborne acrylic resin containing both tert-amino and carboxylic acid groups and a hardener containing both epoxy and alkoxysilyl groups. The waterborne silicone acrylic coatings provide superior film properties even if the acrylic resin has relatively low functional group content. In this paper we describe the crosslinking reaction mechanism and film properties using some acrylic resin types and paint formulations as examples. Presented at the 24th Annual Waterborne, High-Solids, and Powder Coatings Symposium, on February 5–7, 1997, in New Orleans, LA. 1-3 Takasago, Takaishi-shi, Osaka, Japan.     

Fatty acid composition of seed oil triglycerides inCoincya (Brassicaceae)

Oil and triglyceride contents and fatty acid composition were determined for seeds in nine taxa belonging to the genusCoincya (Brassicaceae) on the Iberian Peninsula (Spain and Portugal). The oil content ranges from 11.1 to 24.6%, triglycerides from 68.7 to 88.5%. The major fatty acids were erucic (24.6–30.5%), linolenic (17.7–27.7%), linoleic (13.9–24.6%) and oleic acid (12.3–21.8%).     

Medium-chain fatty acid-rich glycerides by chemical and lipase-catalyzed polyester-monoester interchange reaction

Medium-chain triglycerides (MCT) that contain caprylic acid (C_8:0) and capric acid (C_10:0) have immense medicinal and nutritional importance. Coconut oil can be used as a starting raw material for the production of MCT. The process, based on the interchange reaction between triglycerides and methyl esters of medium-chain fatty acids by chemical catalyst (sodium methoxide) or lipase (Mucor miehei) catalyst, appears to be technically feasible. Coconut oils with 25–28.3% (w/w) and 22.1–25% (w/w) medium-chain fatty acids have been obtained by chemical and lipase-catalyzed interchange reactions. Coconut olein has also been modified with C_8:0 and C_10:0 fatty acids, individually as well as with their mixtures, by chemical and lipase-catalyzed interchange reactions. Coconut olein is a better raw material than coconut oil for production of mediumchain fatty acid-rich triglyceride products by both chemical and lipase-catalyzed processes.     

Production of 15-, 16- and 17-hydroxy-9-octadecenoic acids by bioconversion of oleic acid withBacillus pumilus

SeveralBacillus strains were tested for their ability to hydroxylate oleic acid. Two strains—BD-174 and BD-226—converted oleic acid into a trio of hydroxy-octadecenoic acids. Bioconversion in 72–120 hr produced 5–11% of hydroxy acids relative to oleic acid as measured by gas chromatography. These acids were identified as the 15-, 16- and 17-hydroxy-9-octadecenoic acids by gas chromatography-mass spectrometry of trimethyl silyl derivatives of the product acids and their hydrogenated counterparts.     

A selective catalyst for two-component waterborne polyurethane coatings

The potential for formulating low VOC, high performance, two-component waterborne isocyanate crosslinked coatings has generated a great deal of interest. The difficulties in formulating these coatings, however, are significant. A major problem associated with such systems is the isocyanate-water side reaction, which can lead to gassing/foaming, loss of isocyanate functionality, low gloss, and a reduced pot life. To compensate for this side reaction, these formulations usually contain a large excess of isocyanate. One novel approach to control the water side reaction is the use of catalysts which selectively catalyze the isocyanate-polyol reaction and not the isocyanate-water reaction. The selectivity of a variety of metal catalysts to catalyze the preferred reaction was measured using an FTIR method. A zirconium complex has shown unusually high selectivity for the isocyanate-polyol reaction in comparison to the standard dibutyltin dilaurate catalyst. This zirconium complex catalyst has been evaluated in several waterborne polyurethane formulations and has demonstrated less gassing/foaming, longer pot life, and higher gloss than dibutyltin dilaurate at equal cure time. The mechanism of catalysis and formulating techniques of this novel zirconium catalyst will be discussed. Presented at the International Waterborne, High-Solids, and Powder Coatings Symposium, February 10–12, 1999, New Orleans, LA. Science Rd., Norwalk, CT 06852.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Control of film defects in solventborne high-solids coatings: The non-additives vs. a new additives approach

Acetylenic based surfactants have long found utility in compliant coatings such as waterborne systems and are demonstrated here to enhance performance of solventborne high solids systems. Three new additives are shown to reduce surface defects such as craters and orange peel in conventionally spray applied polyester and epoxy paints. Important to this new additive technology is the lack of adverse effect on physical properties, recoatability, and durability of the applied coating. Also discussed are the theory and background of the origins of surface defects with emphasis on the influence of additives on paint rheology, compatibility, and surface tension. Presented at the Latin American Coatings Show, August 27–28, 1997, Mexico City, Mexico by Joel Schwartz and the 5th International Exhibition of Paint Industry Suppliers, September 15–17, 1997, Sao Paulo, Brazil, by Frank Lee. 7201 Hamilton Blvd., Allentown, PA 18195. 109 Lukens Dr., New Castle, DE 19720.     

Relationship between chemical degradation and thickness loss of an amine-cured epoxy coating exposed to different UV environments

The relationship between chemical degradation and thickness loss of an unpigmented, non UV-stabilized, crosslinked amine-cured epoxy coating exposed to three UV conditions was investigated. Spin-coated samples having a thickness of approximately 7 μm on an Si substrate were prepared from a stochiometric mixture of a bisphenol A epoxy resin and a tetra-functional amine curing agent. Samples were exposed outdoors and to two accelerated laboratory UV environments. Chemical degradation and thickness loss were measured by transmission Fourier transform infrared spectroscopy (FTIRS) and laser scanning confocal microscopy (LSCM), respectively. In addition, surface roughness and morphological changes were measured by atomic forcemicrosocopy (AFM) and LSCM. Substantial chemical degradation, thickness loss, and morpholocal changes occurred in the exposed films, and the rate of chemical degradation was greater than that due to the thickness loss. This additional chemical loss was attributed to an inhomogeneous degradation process in which nanoscale localized depressions initiate at certain sites on the surface, which then enlarge and deepen with exposure time. The results of this study provide a better understanding of the degradation mechanism and should lead to the development of scientific-based models for predicting the service life of crosslinked amine-cured epoxy coatings. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL     

Synthesis,Characterization and Performance of Amine Modified Linseed Oil Fatty Amide Coatings

A novel attempt has been made to develop ambient cured polyamine amide (PAA) resins by the condensation polymerization reaction of oil fatty amide diol (N,N-bis 2-hydroxy ethyl linseed oil fatty amide) (HELA) and o-phenylene diamine, which was further modified by poly(styrene-co-maleic anhydride) (SMA) at different phr (parts per hundred part of resin) to get a series of PAA–SMA resins. The structural elucidation of HELA, PAA and PAA–SMA were carried out by FT-IR, ¹H-NMR and ¹³C-NMR spectroscopic techniques. The physico-chemical and physico-mechanical analyses were carried out by standard laboratory methods. Thermal analyses of these resins were accomplished by thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC) techniques. Coatings of PAA–SMA were prepared on mild steel strips to evaluate their physico-mechanical and chemical/corrosion resistance performance under various corrosive environments. It was found that among the PAA–SMA systems, PAA-35 showed the best physico-mechanical and corrosion resistance performance. Thermal studies reveal that the coatings can be safely used up to 305 °C.     

Mg-rich coatings: A new paradigm for Cr-free corrosion protection of Al aerospace alloys

Environmentally acceptable alternative coatings to chromate pigments and pretreatments for the corrosion control of Al alloy 2024 T-3, commonly used in aircraft, were designed, formulated, and tested as primer coatings to provide protection using particulate Mg-rich pigmentation. The system was designed by analogy to pigmented Zn-rich primer coatings used for the protection of steel. In the current study, four coating polymer systems were examined as possible candidates as polymer matrices for Mg-rich cathodic protect coatings. Mg-rich primers were formulated with ∼50-micron average particle size magnesium powder, near to the critical pigment volume concentration (CPVC) for this system. Top-coated scribed coatings systems have been subjected to Prohesion^™ exposure in dilute Harrison’s solution for up to 5000 hr. These coatings are the first nonchromated coatings to satisfy 3000 hr of such exposure and remain shiny and undamaged in the scribe area, only showing damage at about 4800 hr. The corrosion byproducts generated in the scribe areas during Prohesion exposure were examined by energy dispersive X-ray analysis (EDXA), and the local pH of the coating determined by the nature of the salt formed as a function of exposure conditions and time, did not cause Al corrosion. Presented at the 81 st Annual Meeting of the Federation of Societies for Coatings Technology, November 12–14, 2003, in Philadelphia, PA.     

改性蓖麻油制备UV光固化涂料的研究

研究了改性蓖麻油制备UV光固化涂料。由蓖麻油、环氧丙烯酸树脂UVR6100、光引发剂UVI6990制得的涂料具有优良的光泽、良好的柔韧性、良好的附着力与硬度，且当改性蓖麻油含量为40％时，漆膜性能最为优良。