Alkyd Coatings Research Articles

Evaluation of blistering performance of pigmented and unpigmented alkyd coatings using electrochemical impedance spectroscopy

The influence of pigment on the blistering behaviour of alkyd coating system was investigated using electrochemical impedance spectroscopy, salt spray, visual observation and adhesion techniques. The results showed that the pigment initially enhanced the migration of the environment promoting more number of blisters than the unpigmented system. Over a long period of exposure, however, the unpigmented system was found to be more susceptible to permeation of the environment.

The corrosion protection of steel in sea water using zinc-rich alkyd paints. An assessment of the pigment-content effect by EIS

The effect of pigment volume concentration ( c v,p) on the corrosion resistance properties of zinc-rich paints (ZRP) has been investigated using electrochemical impedance spectroscopy (EIS) combined with cathodic protective potential measurements. Painted naval steel samples were studied during the exposure to artificial sea water for up to 45 days. ZRP coatings were prepared employing zinc pigment content in the 77–88% concentration range. Results show clearly that samples prepared with c v,p values >86% deteriorated more rapidly than panels painted using a relatively lower pigment content. The corrosion behaviour of painted steel samples was found to be practically independent of c v,p within the 78–86% range. The cathodic protection effect in action during 45 days' immersion time arises because these alkyd resin paint coatings behave like a porous active surface layer. Under aggressive conditions similar to those afforded by the artificial sea water, zinc-rich alkyd coatings containing c v,p values within the 78–86% range seem to provide longer corrosion protection to steel substrates than other types of ZRP commonly used.

Wintercure the answer to epoxy coatings for steel construction

New Wintercure rapid recoat systems, from International Protective Coatings, significantly reduces steel section priming, overcoating and handling times — and really comes into its own during the winter. The systems are particularly applicable for steelwork which requires a higher performance than conventional alkyd coatings, such as in aggressive or exposed external environments or where clients require a longer life to first maintenance.

The effect of silanes on paint adhesion and sites of failure

It is shown that the exposure of organic coatings to high humidity or water immersion causes a rapid loss of adhesion. The use of organofunctional silanes of the general formula R1—Si(OR)3, where R1 is an amino, epoxide, mercapto, methacryloxy or vinyl group, can materially improve the initial, wet and recovered adhesion of epoxide, urethane and alkyd coatings to mild steel and aluminium substrates when used as pretreatment primers and additives. XPS work on the locus of failure of surface coatings on aluminium substrates indicated that although some local loss of adhesion to the substrate may occur, the predominant mode of failure is cohesive within the paint film. These findings are discussed in the light of current theories.

Oleo chemicals as additives in paints and varnishes, etc: Part 2

Gelation that can occur when copper or aluminium bronze powder is permitted to stand in nitrocellulose lacquer can be prevented by the addition of below one percent of lauric acid. Butyl acetyl ricinoleate will impart highgloss, plasticity, pliability to nitro‐cellulose lacquers and impart permanence, and improves the ageing properties and low temperature flexibility to the product. Acrylic coatings of improved gloss and pattern control have been provided by the addition of methyl hydroxystearate. When barium α‐sulphostearate is added to interior or exterior paints it can produce films of improved hardness. Methyl linoleate can be employed to retard the hardening of Japanese film lacquer. Compositions with good heat stability and good thixotropic properties and which are suitable for use as a base for paints have been evolved by reacting hydrogenated castor oil with toluene di‐isocyanate and emulsifiable and polyethylene wax. The use of aluminium stearate in paints at elevated temperatures can result in films of high opacity, good build, sag resistance, heavy pigmented tolerance and good sealing properties. Myristic acid‐based alkyd aryl ketones have been utilised to impart lustre to wooden surfaces, and stearic acid terminated polyamide/polyimide for coatings for electrical insulators of magnetic wire have been applied to give improved lustre. Diethylene glycol esters of dilinoleic acid can be used to produce non‐drip paints, as can ethylene diamine bis hydroxystearate, and glyceryl trihydroxystearate. Hydrogenated castor oil is useable in the making of thixotropic agents applicable to paints have been prepared from the material, plus oligomers of hydroxystearic acid/ethylenediamine/sebacic acid polymers. Ethyl linoleate and ethyl linoleate have been used as penetrants in anti‐corrosive paints based upon alkyd resins. Aluminium stearate can prevent excess penetration by paints of surfaces. Bis (hydroxymethyl) propanediol oleate has found use in alkyd resins derivative coatings with butylated melamine resins‐hardening materials to give pinhole resistant coatings. Butyl stearate is a good low temperature plasticiser for paints. Butyl acetyl ricinoleate imparts good plate release and cold crack resistance to leather lacquers, and provides good handle and excellent low temperature flexibility to coated fabrics on thick unsupported sheetings.

Curing of non-pigmented alkyd coatings detected by in-situ photoacoustic fourier transform infrared spectroscopy (PA FT-IR)

Photoacoustic Fourier transform infrared spectroscopy (PA FT-IR) has been utilized for in- situ measurements of the curing processes in alkyd coatings. The spectroscopic data have been correlated to the weight loss measurements and indicate that ca. 33% w/w (solvent-based) highly volatile solvent molecules remain in the coating and may be involved in the curing process. Analysis of infrared spectra indicates that both film formation and degradation of the coating occur almost simultaneously. Alternative mechanisms for network formation are proposed.

Viscoelastic properties and coating performance of acrylic copolymers crosslinked with melamine resin

AbstractFor 8 carboxy and hydroxy functional acrylic copolymers crosslinked with melamine resin, glass transition temperature (Tg), molecular weight of chain segments between crosslinked point (Mc), and polymer‐solvent interaction parameters (χg ) were determined by dynamic mechanical measurements and swelling measurements. Tg increases and Mc decreases with the increase of hydroxyl value and the molecular weight of acrylic copolymers. Tg decreases and Mc increases with the increase of alkyl chain length of acrylate in acrylic copolymers. The film hardness, Tg and polarity of methyl methacrylate (MMA) containing acrylic‐melamine‐cured films are higher than those of styrene‐containing acrylic‐melamine‐cured films, but both films are almost the same in the degree of crosslinking (maximum loss tangent, tan δmax, and Mc). Tg increases and Mc decreases with the increase of melamine resin content for acrylic‐melamine coatings. The cured film consists of the acrylic‐melamine segments and the melamine‐melamine segments at crosslinking points. The carboxy group enhances the crosslinking reactions at low temperatures. All films crosslinked have single glass transition temperatures and broad damping peaks, which show good compatibility. The values of χg of acrylic copolymer‐melamine films in polar and nonpolar solvents depend on the polarity of acrylic composition and the degree of crosslinking. χg values of carboxy functional acrylic‐melamine film in any solvents are smaller than that of carboxy and hydroxy functional acrylic‐melamine film. χg values of MMA‐containing acrylic‐melamine film in polar solvents are smaller than those of styrene‐containing acrylic‐melamine film, but χg values of MMA‐containing acrylic‐melamine film in nonpolar solvents are larger than those of styrene‐containing acrylic‐melamine film. χg values of acrylic‐melamine film in polar and nonpolar solvents increase with the increase of alkyl chain length of acrylate. The χg values of acrylic‐melamine coatings in toluene are less than 0.3 and smaller than those of alkyd coatings.

Water reducible industrial coatings

This paper details the use of isophthalic acid and trimellitic anhydride for the design and production of water reducible alkyd coatings. The performance of these systems is equal to or better than conventional solvent based systems. The use of special processing, compounding or application equipment is not required for the production of these coatings, however, the raw materials must be carefully selected to ensure optimum performance. Both water reducible alkyds and water reducible acrylated alkyds for air drying and force cured applications will be discussed. Coatings manufacturers in the United States have commercialized these systems for applications varying from air dry implement enamels to interior can coatings.

Effects of temperature on rates of permeation of chloride ions and water vapour through alkyd coatings

Organic Coatings are used for protection of metallic structures from corrosion. However they fail to isolate the substrate from corrosive materials present in the surroundings because the amount of water absorbed in coatings facilitates the movement of corrosive ions and gases through them, which in turn corrode the metal. The present studies illustrate the relative degree of permeation of chloride ions and water vapour through a variety of alkyd coating formulations.

Effect of temperature on rates of permeation of chloride ions and water vapour through alkyd coatings —

Organic Coatings are used for protection of metallic structures from corrosion. However they fail to isolate the substrate from corrosive materials present in the surroundings because the amount of water absorbed in coatings facilitates the movement of corrosive ions and gases through them, which in turn corrode the metal. The present studies illustrate the relative degree of permeation of chloride ions and water vapour through a variety of alkyd coating formulations.

Materials

Granges Essem (UK) has just introduced new, very durable, polyvinylidene fluoride (PVF2) colour‐coated aluminium sheeting. This extends the choice of finishes already available, which include the well known PVC Organosol and alkyd melamine Metallack coatings.

Effect of quartz sand filler on the mechanical and thermophysical properties of alkyd and epoxy coatings

The effect of a filler on the mechanical and thermophysical properties of polymer coatings has been investigated. It is shown that quartz sand particles are centers of structure formation in alkyd and epoxy coatings. It has been found that a denser, oriented, and stressed polymer structure, much exceeding the size of the individual macromolecules, is formed around the filler particles. The size of the spheres around the filler particles depends on the nature of the film-former, on the filler surface, and on the filler content. It is postulated that secondary supermolecular structures, and not individual polymer macromolecules, are adsorbed on the surface of the filler particles.

Effect of reaction at the polymer-solid interface on the mechanical properties of alkyd coatings

IR spectroscopy is used to investigate the intermolecular reaction between alkyd resin and the surface of aerosil. It is shown that the nature of the reaction has a considerable influence on the mechanical and adhesion properties of the coatings. Modification of the aerosil surface with octadecylamine leads to the formation of a hydrogen bond between the NH groups of the modifier and the OH groups of the aerosil surface. In the presence of alkyd resin the NH groups are almost completely displaced from the surface of the filler.

A study of the life of alkyd coatings

The effect of the conditions of formation and aging on the life of alkyd coatings is studied. It is shown that the life of alkyd coatings aged under various conditions can be expressed by the general equation τ=Ae−ax The relationship between the life of alkyd coatings and curing temperature is linear. It is observed that the conditions of aging have no effect on the rupture energy or τ0, but cause a substantial change in the distribution of the lines τ=f(1/Tf). Cross-linkage of alkyd coatings due to the action of heat, light, and moisture, under various conditions of aging, is accompanied by an increase in rupture energy with increase in the internal stresses.

メラミン・アルキド皮膜の架橋と力学的性質

メラミン・アルキド皮膜についてアルキドの脂肪酸の種類を変えることにより, その架橋構造と力学的性質の関連性について検討した。(1) 皮膜の剛性率測定の結果, ラウリン酸, ステアリン酸<オレイン酸<リノール酸の順に高温剛性率が高く, 二重結合による架橋密度の増大が認められた。(2) 皮膜の平衡膨潤量, 膨潤膜の剛性率測定結果からも, (1) と同じ傾向が認められた。(3) 膨潤皮膜について, ゴム域における静的ひっぱり応力-ヒズミ関係のヒステレシス曲線を描いた場合, ラウリン酸, ステアリン酸使用のものは, 荷重1.8kg/cm2を加え, 次に除重しても永久変形が認められ, オレイン酸使用のものはわずかに永久変形が認められたが, リノール酸使用のものは同一荷重における変形量が小さく, しかも3.1kg/cm2の荷重を加え, 次に除重した場合も永久変形を示さなかつた。

脂肪酸変性アルキッド樹脂およびエポキシ樹脂塗料の性質におよぼす脂肪酸組成の影響

脂肪酸変性アルキッド樹脂およびエポキシ樹脂塗料の性質におよぼす脂肪酸組成の影響