Carlos A. Giúdice

Zinc borates as flame-retardant pigments in chlorine-containing coatings

Abstract This paper discusses the influence of zinc borates with molecular formulas of 2ZnO·3B2O3·3.5H2O and 2ZnO·3B2O3·7.5H2O used for substituting antimony trioxide on the performance of chlorinated alkyd, flame-retardant coatings. Experimental coatings were manufactured on a laboratory scale, applied by brush on wood panels (Araucaria Angustifolia) and finally tested in a limiting oxygen chamber (LOI values), in a flame cabinet (intermittent bunsen burner rating) and in a two-foot flame tunnel (flame-spread index, panel consumption, after-flaming and after-glow). Results of laboratory tests indicated that coatings with a chlorine-containing resin used as the film-forming material, zinc borates can act as a flame retardant.

Research and development of soluble matrix antifouling paints for ships, offshore platforms and power stations. A review.

Antifouling paints research and development deal with the deterioration produced by fouling in ship hulls, offshore platforms, power stations refrigerating equipments, etc. The use of antifouling paints is the most satisfactory and economical method for submerged structures protection. The principal variables studied were related to binders (type of resin, type of plasticizer, resin/plasticizer ratio, sea water dissolution rate), to the pigments (type and content of toxicant, inert pigment and extender, particle shape and size), to the additives (rheological, dispersant and antisettling agents), to the elaboration processes (ball mills operative condition, dispersion time, reaction involving pigments and acidic components of binder), to the immersion tests (raft and ships hull, dry film thickness, immersion time, neutralization chemical reactions between sea water cations and remaining acidic components of binder) and, finally, characteristics of aged paints after storage (physical and mechanical properties of paint film and paint bioactivity). Antifouling paints included in these studies were formulated using mainly red cuprous oxide; other toxicants, as zinc oxide, TPTF, TBTF and TBTO were also employed. Binders were prepared on the basis of a sea water soluble resinous material (WW rosin or calcium resinate) and a phenolic varnish, chlorinated rubber or vinyl resin as co-binder. The paints were manufactured using ball mills of 3.3, 10.9, 28.5, 141.5 and 400.8 liters capacity. The paints were tested in two experimental rafts, which were anchored at Mar del Plata and Puerto Belgrano harbours and also on the hulls of different ships: aircraft carrier, cruiser, destroyers, and tugboats. Some formulated paints showed a satisfactory fouling control during 18, 24 and 36 months immersion in temperate sea water and in the presence of high aggresive species. Sixteen compositions of oleoresinous, chlorinated rubber and vinyl efficient antifouling paints were included in this paper. They were selected from the studies made by the CIDEPINT research team in Argentine.

Optimising the corrosion protective abilities of lamellar micaceous iron oxide containing primers

Lamellar micaceous iron oxide paints are successfully employed to provide longlife corrosion protection for metallic structures when exposed to highly aggressive environments. The aim of this work was to formulate and manufacture lamellar micaceous iron oxide paints, able to be used on the protection of steel structures exposed to water. Several formulation and manufacture variables were taken into account. Many paint films fail when they are saturated with moisture and blistering is a common failure because primers usually are not designed to allow the liquid to dissipate back out through the film. Consequently the film can not resist the formation of projections which result in local adhesion loss. For maximum durability, primers must be properly formulated and manufactured. Film permeability, which depends on paint composition (pigment volume concentration) and micaceous iron oxide dispersion time, seems to be the key characteristic controlling subsequent coating performance. Laboratory results indicated that lamellar micaceous iron oxide is a pigment which provides an anticorrosive action by providing a barrier effect. Film permeability must be compatible so as to attain a satisfactory rusting and blistering resistance.

High-build soluble matrix antifouling paints based on vinyl resin

Abstract The aim of this work was to formulate and evaluate high-build, soluble matrix antifouling paints showing reduced solvent retention in the film and sufficient bioactivity to protect structures submerged in sea water for long immersion periods. The variables analyzed were binder composition, pigment content, toxicant type and thixotropic agent content. Binder dissolution in sea water was achieved by employing WW rosin or calcium resinate; the control of the binder dissolution rate was achieved by using a vinyl resin as a cobinder. The paints were formulated with pigment volume concentrations of 40 and 45%; red cuprous oxide and triphenyl tin fluoride were used as the main toxicants. The rheological additive employed was hydrogenated castor oil at levels of 2.0 and 2.5 wt.% in the paint. The bioactivity of the antifouling paints was determined in the natural environment (30 month immersion in sea water).

The use of calcium resinate in the formulation of soluble matrix antifouling paints based on cuprous oxide

Abstract In a previous paper, the authors studied the changes produced in the film composition of antifouling paints based on WW rosin/chlorinated rubber during immersion in artificial sea water for different periods. The results obtained established that the free resinic acids were neutralized forming resinates and also that film dissolution took place fundamentally by solubilization of these resinates. Following these conclusions, antifouling paints based on calcium resinate, calcium resinate/chlorinated rubber and WW rosin/chlorinated rubber were formulated and made in a laboratory ball mill of 3.3-1 capacity. The experimental results of immersion raft trials (26 months) were statistically treated (factorial design 2×2×2×3×4, 96 samples prepared and tested in duplicate) and the conclusions then correlated with binder acid values obtained from laboratory analysis. The study showed the influence of composition variables (type of soluble resinous material, resinous material/chlorinated rubber ratio and binder content) and also the importance of some manufacturing variables (order of incorporation of the resinous material and toxicant, and cuprous oxide dispersion time) on the biocidal characteristics of the paints.

High-build soluble matrix antifouling paints tested on raft and ship's bottom

Abstract The characteristics and properties of some experimental high-build soluble matrix antifouling paints have been studied. Thixotropic samples were formulated with WW rosin and Grade 10 chlorinated rubber as a binder, using red cuprous oxide as the main toxicant and zinc oxide as the reinforcing toxicant. Non-thixotropic reference samples having the same composition but prepared with Grade 20 chlorinated rubber in the formulation were also used. Rheological additives at 2.0 and 1.0% concentrations were employed for the high-build and conventional formulations, respectively. The paints were tested by means of raft and ship trials to determine their bioactivity. Films of 50–60 and 100–120 μm thickness were evaluated to establish the influence of this variable on the antifouling characteristics of the prepared products. Good antifouling protection extending to 14, 26 and 36 months was obtained with some of the samples tested on raft panels and up to 25 months for the paints applied on the ship hull.

Pigment dispersion degree and its evolution in storage

The current size of individual particles in most pigments is usually below 1μm; this ensures powerful forces of attraction causing the particles to cling to one another forming aggregates. If pigment dispersion stability is not appropriate, particles join again and form flocculates. It is important to know the initial degree of dispersion, its evolution during coating storage and the influence on its dry film anticorrosive properties. Several anticorrosive coatings were formulated starting from an epoxy resin as binder, tin tannates as inhibitor and a red iron oxide‐micronised talc mixture as inert pigment. Variables studied were pigment dispersion time and coating ageing time in storage. The degree of dispersion was determined by optical photomicroscopy to establish the shape and size of associated particles present in the system. The flow properties of anticorrosive coatings due to the different dispersion degree were evaluated through rheological tests. Coating film behaviour was also assessed for several dispersion times and ageing periods in laboratory, employing a salt spray (fog) cabinet and a 100 per cent relative humidity chamber.

Flame-Retardant Systems Based on Alkoxysilanes for Wood Protection

Giudice, Carlos A. UTN (Universidad Tecnologica Nacional); Argentina. CIDEPINT (Centro de Investigacion y Desarrollo en Tecnologia de Pinturas); Argentina

Anticorrosive Paints with Flame Retardant Properties

Anticorrosive paints with flame retardant properties based on a chlorinated alkyd resin were formulated. Micaceous iron oxide, leafing aluminium, mica and zinc hydroxyphosphite were employed as pigments. Antimony trioxide was incorporated to obtain fireproofing action in halogenated organic compounds. The anticorrosive capacity of the paints is related to the adequate selection of pigments and binder. The influence of PVC values between 35.0 and 60.0 % was studied. Paints were prepared by employing a ball mill whose operating characteristics were specially considered to obtain an efficient pigment dispersion. SAE 1010 tests panels, sandblasted to Sa 2 1/2 (SIS 05 59 00-1967) to obtain 20 μηι of maximum roughness were employed. The experimental paints were applied by brush obtaining 100±5 μηι dry film thickness. Then, their inhibitive behaviour was assessed in salt spray (fog) testing and in 100 % relative humidity cabinet while the flame retardant property was established by determining the limiting oxygen index (LOI).