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ArtigoBrochura
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - Two-component (2K) waterborne polyurethane coatings are a new technology which has been demonstrated in a number of heavy duty applications. They exhibit performance properties equivalent to 2K solvent-borne polyurethanes, with the advantage of reduced volatile organic compounds (VOCs). Although the use of these systems has been demonstrated successfully, the details of their film formation mechanism have not been established. With a better understanding of these factors, the chemistry and...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - An attractive strategy for zero VOC coatings involves blends of hard and soft latex particles. A dispersion of a latex with a low minimum film-forming temperature will form a transparent film upon evaporation, even when blended with a substantial amount of high Tg latex. The low Tg latex deforms to fill space as the dispersion dries, and the high Tg component imparts good block resistance and mechanical properties to the final film. Transparency requires that the hard latex be sufficiently...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - With increasing environmental pressures and resulting government regulations, the coatings industry is undergoing a rapid shift in technology in an effort to reduce volatile organic content (VOC) levels. Thus, we have successfully synthesized novel, solvent free, ambient cure, vinyl acrylic, and acrylic latexes with dimethyl meta-isopropenyl benzyl isocyanate (TMI) as the curing agent. The emulsion polymers were formulated into solventless coatings and their properties contrasted to...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - Dibromostryene can copolymerize with butadiene, alkyl acrylates and methacrylates, vinyl acetate, styrene, and unsaturated carboxylic acids to form a wide variety of flame-retardant latexes via an emulsion polymerization technique. The latex is characterized in terms of glass transition temperature, residual monomer, solids content, pH, Brookfield viscosity, specific gravity, particle size, mechanical stability, UV stability, and flame retardancy. These novel dibromostyrene-based latexes are...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - Radiation curing is increasing at a rapid pace. This paper highlights the topic of flow control agents in radiation curable coatings.
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - The microencapsulation of toluene 2,4-diisocyanate dimer (di-TDI) was accomplished by interfacial polycondensation with ethylene diamine in cyclohexane and in a polycaprolactone; the influence of different parameters was discussed. The microcapsules obtained were characterized according to morphology and NCO content. Their behavior in two polycaprolactones was studied. The reaction between NCO and OH groups took place only after the isocyanate melting when encapsulation was well done....
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - New inorganic/organic hybrid coatings have been prepared utilizing linseed oil and sunflower oil as an organic phase and two sol-gel precursors [titanium (IV) i-propoxide, titanium (di-i-propoxide) bis(acetyl-acetonate)] as an inorganic phase. The ultimate goal is to develop a primer that will provide better adhesion and corrosion protection for metal substrates with minimal environmental impact. Coatings with a range of sol-gel precursor to drying oil ratios have been studied....
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - Although present in relatively low concentrations, additives such as thickeners, rheology modifiers, dispersants, and surfactants can contribute to the water sensitivity of coatings due to their inherent affinity for moisture. Because of the number of additives often present and the variable response possible within different formulations, a method was sought to examine the moisture affinity of individual additives in the absence of other coating components. A simple gravimetric procedure...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - In an attempt to improve the toughness and flexibility of poly(epoxy-urethane-acrylic), interpenetrating polymer network (IPN) coatings conventional bisphenol A type epoxy was replaced with silicone containing epoxy. By comparing silicone epoxy containing samples with bisphenol A controls, the effect of siloxane modification on the properties of the materials thus formed were tested. The coatings were formulated to typical automotive primer conditions (in the absence of any pigments)...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - A unified model is presented for the degradation of an organic protective coating on a steel substrate exposed to a neutral electrolytic environment. This model is based on theoretical and experimental studies from our laboratory and on current understanding of the degradation process. The assumptions of the model are based on the concept that degradation of a coating/steel system occurs following the transport of ions through conductive pathways, which are presumably formed by an attack by...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - The mechanism by which polymer microgels impart shear-thinning behavior and a yield stress to the Newtonian, low molecular weight resin of high-solids solvent-borne automotive coatings is not well understood. Toward identifying this mechanism, we measured the viscosity of several microgel dispersions as a function of particle volume fraction as well as the size and polydispersity of the particles. Variations in the relative "softness" of the particles, due to differences in the steric layer...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - Traditionally persulfates have been used as initiators in redox water-based polymerizations systems. While persulfates are still used industrially, the use of organic peroxides has increased during the past decade. This paper summarizes work which shows that organic peroxides can be used as highly effective monomer scavengers to reduce the levels of unreacted residual monomer in a latex. In addition, organic peroxides can be used in place of persulfates for initiating a redox polymerization...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - Experimental techniques have been developed to investigate the migration of UV absorbers and hindered amine light stabilizers taking place in acrylic/melamine clearcoats during cure. The basic approach consisted of microtoming the coatings into thin sections and measuring the additive concentration of each section. The stabilizer migration within single-layer coatings and between adjacent clearcoat layers was investigated. The effect of resin viscosity and layer swelling on the migration...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - Previous research results involving sulfur accumulation on cross sections of wood coated with latex paint led us to investigate whether acidic conditions could affect the bonding strength of paint and be a factor in catastrophic paint peeling. Through simulation of acidic dew under outdoor conditions, the study reported herein determined the effect of acid rain and/or dew on painted wood siding. Painted wood was soaked before dawn in various acid solutions for two hours each day, then exposed...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - The ability to prepare solvent-borne, high-solids, coating resins has been hampered by the need to use resins which have lower than desired Tgs or use more solvent than would be preferred to reach application viscosity. Recent work has indicated that cyclic, higher Tg, methacrylate monomers that are incorporated into a styrene/acrylic copolymer may be effective in reducing solution viscosity. This work will discuss the effect of incorporating different cyclic methacrylate monomers on solution...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - Corrosion inhibitor mechanisms in model epoxy coating systems on aluminum were studied with electrochemical impedance spectroscopy (EIS). The emphasis of the work was on the eventual formulation of non-toxic corrosion inhibitors into barrier-type zero discharge organic coatings (ZDOC) such as powder, UV-curable, waterborne, and electrocoat systems. A methodology was developed based on EIS measurements on coating-metal systems comprised of barrier coatings with defects, porous coatings, and...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - Grafting of maleic anhydride onto low molecular weight guayule rubber, followed by chlorination of the residual double bonds provides a powder reactive to alcohols, amines, and epoxides. The product, chlorinated-maleinized guayule rubber, is a potential crosslinker/additive for powder coating formulations. Accordingly, polyester-hydroxyalkylamide and epoxy-polyester hybrid powder coating formulations were developed, applied, tested, and contrasted to properties of commercial powder coating...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - The effect of the adsorption of an anionic surfactant (aerosol OT, sodium dodecyl sulfate, sodium dodecyl sulfonate, or sodium dodecyl benzene sulfonate) on the dispersion behavior of some types of titanium dioxide pigments has been studied. Surfactant adsorption isotherms and the kinetics of the adsorption process were linked using a full Langmuir model. Sedimentation experiments were used to assess the dispersibility of the powders in two non-polar dispersion media (nonane and cyclohexane)....
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - The adhesion of organic coatings to polyolefin substrates is strongly dependent upon the type of surface treatment the thermoplastic material receives prior to painting. One such treatment involves the application of a thin layer (7-14 micron) of an adhesion promoting primer that is comprised of a chlorinated polyolefin polymer. Although materials of this type are known to establish good adhesion between the thermoplastics olefin (TPO) and subsequent paint layers, the mechanism of adhesion...
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Artigo
FSCT - Journal of Coatings Technology and JCT Research - The influence of relative humidity on the rate of isocyanate functionality depletion at the filmÑair and filmÑsubstrate interfaces of a urethane coating was examined using attenuated total reflectance (ATR) FTIR. The effect of relative humidities ranging from 0 to 80% on crosslinking reactions was examined. The results indicate that reactions of isocyanate groups with OH functionalities are inversely proportional to the relative humidity. The results are discussed in terms of the reactions...