Quaternary Ammonium “Tannate” for Antifouling Coatings

The undesirable accumulation of a wide variety of marine organisms (biofouling) on ship hulls can lead to significantly increased costs, principally by increased fuel consumption to maintain cruising speed. Generally, these coatings have bioactive compounds, called biocides. In this sense, this paper deals with the assessment of the antifouling properties of a natural product derivative obtained from "quebracho" tannin and a quaternary ammonium salt (hexadecyltrimethylammonium bromide ([CH3(CH 2)15N(CH3)3]Br). Two derivatives were obtained depending on the precipitation pH (4 and 8). The bioactivity of these derivatives was assessed by means of the Artemia test. Furthermore, soluble matrix paints were prepared with two different binders: rosin/oleic acid and rosin/styrene-acrylate copolymer. The leaching of "quebracho" tannin derivatives from coatings in artificial seawater was monitored until constant values were obtained, previous to the immersion in natural environments. Finally, the antifouling activity of coatings pigmented with the "quebracho" tannin derivative was evaluated in Mar del Plata harbor (38°08′17″S-57 31′18″W). The coating obtained with the derivative obtained at pH 4 and rosin/oleic acid as binder proved to have an acceptable efficiency for 10 months.Fil: Bellotti, Natalia. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: del Amo, Delia Beatriz. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: Romagnoli, Roberto. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentin

Quaternary Ammonium “Tannate” for Antifouling Coatings

The undesirable accumulation of a wide variety of marine organisms (biofouling) on ship hulls can lead to significantly increased costs, principally by increased fuel consumption to maintain cruising speed. Generally, these coatings have bioactive compounds, called biocides. In this sense, this paper deals with the assessment of the antifouling properties of a natural product derivative obtained from "quebracho" tannin and a quaternary ammonium salt (hexadecyltrimethylammonium bromide ([CH3(CH2)15N(CH3)3]Br). Two derivatives were obtained depending on the precipitation pH (4 and 8). The bioactivity of these derivatives was assessed by means of the Artemia test. Furthermore, soluble matrix paints were prepared with two different binders: rosin/oleic acid and rosin/styrene-acrylate copolymer. The leaching of "quebracho" tannin derivatives from coatings in artificial seawater was monitored until constant values were obtained, previous to the immersion in natural environments. Finally, the antifouling activity of coatings pigmented with the "quebracho" tannin derivative was evaluated in Mar del Plata harbor (38°08′17″S-57 31′18″W). The coating obtained with the derivative obtained at pH 4 and rosin/oleic acid as binder proved to have an acceptable efficiency for 10 months.Centro de Investigación y Desarrollo en Tecnología de Pintura

Antifouling Paints with Zinc “Tannate”

During the past decade, the necessity of new ecofriendly antifouling pigments was established. Among these new pigments, special attention should be paid to tannin and its derivatives. Tannins are synthesized by plants as part of their defense mechanism against the attack of pathogens. The objective of this work was to study the antifouling efficiency of paints containing zinc “tannate” in artificial seawater. The zinc “tannate” was precipitated at pH 4 and pH 8. Insoluble and soluble matrix antifouling paints, with different plasticizers, were formulated and tannins leached from the paints immersed in artificial seawater were determined by the Folin-Denis assay for polyphenols. The antifouling action of paints was assessed in a natural seawater environment. The results showed that the leaching rate of tannin from insoluble matrix paint decreases, reaching a constant value after 25 days of immersion. In the case of the soluble matrix paints, a lesser amount of tannin was leached, depending on the tannin and the plasticizer employed. The results in a natural sea environment are dependent on the matrix and the plasticizer employed.Centro de Investigación y Desarrollo en Tecnología de Pintura

Antifouling Paints with Zinc “Tannate”

During the past decade, the necessity of new ecofriendly antifouling pigments was established. Among these new pigments, special attention should be paid to tannin and its derivatives. Tannins are synthesized by plants as part of their defense mechanism against the attack of pathogens. The objective of this work was to study the antifouling efficiency of paints containing zinc “tannate” in artificial seawater. The zinc “tannate” was precipitated at pH 4 and pH 8. Insoluble and soluble matrix antifouling paints, with different plasticizers, were formulated and tannins leached from the paints immersed in artificial seawater were determined by the Folin-Denis assay for polyphenols. The antifouling action of paints was assessed in a natural seawater environment. The results showed that the leaching rate of tannin from insoluble matrix paint decreases, reaching a constant value after 25 days of immersion. In the case of the soluble matrix paints, a lesser amount of tannin was leached, depending on the tannin and the plasticizer employed. The results in a natural sea environment are dependent on the matrix and the plasticizer employed.Centro de Investigación y Desarrollo en Tecnología de Pintura

Assessment of tannin antifouling coatings by scanning electron microscopy

It is well known that during the first minutes of the immersion of any substrate in marine environments microbial colonization takes place. This event will condition the attachment of other more complex organisms and the substrate biodeterioration with concomitant loss of its functionality. The aim of this work was to assess antifouling coatings performance at early stages of immersion, in natural and artificial sea water, observing the surface condition, by scanning electron microscope (SEM), in order to predict possible results in long time immersion tests. The use of short time tests to predict future behavior is useful to adjust formulations, reduce testing time and economics cost. In this research antifouling (AF) coatings formulated with two “quebracho” tannin derivatives were chosen to be evaluated by short and long time tests. One of this coatings possessed in a longer service life, until 10 months of exposure, and at the same time, this resulted correlated with surface analysis at early stages of immersion by SEM.Centro de Investigación y Desarrollo en Tecnología de Pintura

"Quebracho" tannin derivative and boosters biocides for new antifouling formulations

The growth of fouling communities on ships' hulls causes economic losses due to increased fuel consumption and to the deterioration of the metallic substrate by corrosion. Antifouling paints are formulated to avoid the settlement of these organisms and may contain biocides as active compounds. The objective of this research was to evaluate the antifouling performance of paints formulated with a "quebracho" tannin derivative (zinc "tannate") and "boosters" (secondary biocides). The "boosters" used in this study were bismuth lactate, a zeolite exchanged with silver cations, and the same zeolite modified with silver chloride. Bioassays with "boosters" solutions were carried out employing Artemia persimilis. Soluble matrix antifouling paints were formulated and their action was assessed in a natural sea water environment. Results showed that the bismuth lactate resulted in a coating with almost triple service life of the antifouling paints with zinc "tannate." Paints formulated with the silver composites behaved slightly better than the control paint.Centro de Investigación y Desarrollo en Tecnología de Pintura

Tara tannin a natural product with antifouling coating application

The international trade by marine transportation has increased continuously since the 70s. The undesirable accumulation of a wide variety of marine organisms (biofouling) on ship hulls can lead to significant increased costs, principally by increased fuel consumption. On the other hand, there is a great concern about the biocides commonly used in commercial antifouling (AF) protective systems due to the high concentration encountered in coastal areas and the potential damage they could cause to marine organisms. As a consequence, the development of alternative AF coatings with new natural products as biocides inhibit is a key factor. In this approach, tara tannin (TT) is being proposed as a promising solution. It is important to note that TT is obtained from the pods of the tree avoiding its cutting down. The aim of this research was, primarily, to explore the possible application of a natural and abundant product, such as the TT, in the preparation of AF coatings. So, a TT derivative was obtained and characterized to be employed as the bioactive compound in AF coatings. Previous to the immersion in natural environments, the dissolution of TT from AF coating in artificial sea water (ASW) was studied. TT was incorporated into the coating as zinc "tannate". One of the tested coatings proved to be efficient in AF protection in natural sea water (NSW) at Mar del Plata (38°08′17″S-57°31′18″W) harbor during eight months. The addition of 2% by weight of zinc oxide to the coating extended its service life until the year.Centro de Investigación y Desarrollo en Tecnología de Pintura

The assessment of a smart anticorrosive coating by the electrochemical noise technique

Zinc phosphate and related compounds are convenient replacements for chromates. However, more eco-compatible pigments are being investigated. The objective of this research was to develop a modified zeolitic rock which is intended to replace phosphate pigments in anticorrosive paints. The modified zeolitic rock was obtained by grinding the rock followed with ionic exchange with molybdenyl ions. This “composite” has an intelligent behavior because molybdenum compounds are leached from the zeolite particle by corrodent species. The anticorrosive properties of this zeolitic rock were studied by electrochemical techniques, employing inhibitor suspensions, and formulating anticorrosive coatings. Coatings performance was evaluated by accelerated tests (humidity chamber and salt spray) and electrochemical noise measurements (ENM). Electrochemical noise data were analyzed in the time domain. The noise resistance (Rn) was compared, as far as possible, with the polarization resistance. It was demonstrated that zinc phosphate content could be reduced to one-third with respect to the recommended value in the literature. The electrochemical noise technique allowed to differentiate the anticorrosive performance of the different coatings formulated in this research.Centro de Investigación y Desarrollo en Tecnología de Pintura

The assessment of a smart anticorrosive coating by the electrochemical noise technique

Zinc phosphate and related compounds are convenient replacements for chromates. However, more eco-compatible pigments are being investigated. The objective of this research was to develop a modified zeolitic rock which is intended to replace phosphate pigments in anticorrosive paints. The modified zeolitic rock was obtained by grinding the rock followed with ionic exchange with molybdenyl ions. This “composite” has an intelligent behavior because molybdenum compounds are leached from the zeolite particle by corrodent species. The anticorrosive properties of this zeolitic rock were studied by electrochemical techniques, employing inhibitor suspensions, and formulating anticorrosive coatings. Coatings performance was evaluated by accelerated tests (humidity chamber and salt spray) and electrochemical noise measurements (ENM). Electrochemical noise data were analyzed in the time domain. The noise resistance (Rn) was compared, as far as possible, with the polarization resistance. It was demonstrated that zinc phosphate content could be reduced to one-third with respect to the recommended value in the literature. The electrochemical noise technique allowed to differentiate the anticorrosive performance of the different coatings formulated in this research.Centro de Investigación y Desarrollo en Tecnología de Pintura

Ensayos de intemperie de pinturas acuosas

La protección por medio de pinturas es una forma barata y efectiva de proteger el acero de la corrosión en ambientes agresivos. En los últimos 30 años el fosfato de cinc ha sido el pigmento anticorrosivo más utilizado y ha reemplazado a los tradicionales a base de cromato y de compuestos de plomo. Sin embargo, a pesar de que este nuevo pigmento da, generalmente, buenos resultados, en algunos casos, la protección que brinda al acero no es satisfactoria. Como consecuencia de esto, una segunda generación de pigmentos fue introducida adicionando al fosfato de cinc compuestos como hierro, aluminio y molibdeno [1-7]. Los pigmentos de esta nueva generación han dado protegido el acero, en ensayos acelerados, mejor que el propio fosfato de cinc. Además de las modificaciones llevadas a cabo sobre el fosfato de cinc, ha habido un desarrollo importante en resinas en base acuosa con el objetivo principal de disminuir la contaminación ambiental que produciría el uso de solventes orgánicos como el aguarrás, el xileno, etc. El uso de este tipo de resinas, en pinturas anticorrosivas, no está muy estudiado sobre todo en lo que respecta a ensayos de larga duración como es el de exposición a la intemperie. Los ensayos de intemperie son importantes ya que dan por resultado el comportamiento real que tendrá la pintura en servicio. La gran desventaja que presentan es su larga duración, pero ningún ensayo acelerado puede simular la variedad y complejidad de condiciones que se presentan en un ambiente natural. El objetivo de este trabajo fue el de evaluar la protección que brindan al acero pigmentos anticorrosivas seleccionados en pinturas epoxídicas de base acuosa. Los pigmentos seleccionados fueron fosfato de cinc (ZP), fosfato básico de cinc (ZBP), fosfato de cinc y hierro (ZFP), fosfato de cinc y aluminio (ZAP) y molibdofosfato de cinc (ZMP).Centro de Investigación y Desarrollo en Tecnología de Pintura