HIGH PERFORMANCE INDUSTRIAL COATINGS

449

HIGH PERFORMANCE INDUSTRIAL COATINGS THOMAS M, SANTOSUSSO Ajr Products and Chemicals, Inc. 7201 Hamilton Boulevard Allentown, PA 18195-1501

Introduction General Principles of Design of High Performance Coatings Epoxy Binders Polyurethanes Melamine Resins Fluoropolymers Silicone Resins Other High Performance Coating Resins Conclusions

Introduction Coating systems can be thought of as serving two major functions - protection and decoration. When the protective function clearly becomes the more important of the two, especially under service conditions of exposure to particularly aggressive agents of corrosion or chemical attack, or to extremes of temperature, radiative energy or wear, the appropriate coatings may be fairly labeled as "high performance." Such conditions are often found in coating applications such as aerospace, marine, and military equipment; power generation, waste treatment, and petroleum and chemical processing sites; and pipeline and tank facilities, including those involving secondary containment. The usual substrate for such applications is almost always a metal or concrete, although more recently protection of composite structures or ceramics has gained some importance. In this review, emphasis will be placed on the application and performance properties of the organic binder systems used in such coatings. Particular stress will be laid on field-applied coatings, as opposed to factory-applied or Original Equipment Manufacturer (OEM) coatings. Thus coatings which are capable of application and full property development under ambient conditions are treated most extensively here, though others will be discussed.

450

T.M. Santosusso

All the components of the coating systems used in high performance applications are important, from surface preparation and application methods to the components of the coating itself - pigment, binder, additives and carrier liquid. All these have evolved significantly over the years as the successful operation of our modern technological society has come to rely more and more on that "thin coat of paint." However, as mentioned above, in this review special (though not exclusive) attention will be paid to the polymeric binder matenals, particularly those which have been developed in more recent times to meet those needs. For this reason, with the exception of the initial section which outlines the general considerations Involved in designing a high performance coating, the review is organized by binder types. Although this approach inevitably leads to some overlap and possible ambiguity in organization, it does provide for easy accessibility and hopefully a good overview of the fields included. Each section includes a brief summary of the chemistry involved, a short history of the materials traditionally employed, a review of modern developments and finally some speculation as to the future of the technology. General Principles of Design of High Performance Coatings As alluded to above, a number of factors must be considered in the design of a high performance coating. These have been summarized in several excellent reviews.^ The most significant design elements obviously are those associated with the overall properties of the intact coating film. The most obvious of these is the ability of the coating to act as a barrier to the external environment. The most important factor in that regard is the permeability of the film to agents which can cause degradation of the underlying substrate. These agents include: oxygen*; solvents; acids, bases, oxidants and other reactive chemicals, including gases and vapors; and water vapor and aqueous solutions , particularly solutions of electrolytes. Just as important is the maintenance of these properties throughout the expected service life of the coating. This in turn depends upon the ability of the coating film to remain intact and adherent to the substrate in the face of attack by these agents while resisting changes due to weathering, temperature cycling, cleaning, abrasion and impact. Film properties in turn are dependent on the properties and interactions of all the components present in the final cured coating. These include the binder resin; fillers and pigments, including color-carrying and opacifying pigments, inert and reinforcing fillers, and so-called active fillers which react with environmental agents to Inhibit corrosion of the substrate; and the host of additives which can be present, such as pigment dispersants, wetting agents, flow and leveling agents, other surfactants, rheology modifiers, defoamers, deaerating agents, adhesion promoters, coupling agents, flash rust inhibitors, antioxidants, photostabilizers, plasticizers, catalysts, and so on. Although this review is centered on the properties of the organic binder, it must * In metal coatings, the rate of oxygen transmission (as well as water vapor transmission) through most films is so high as to discount the simple concept of a barrier function as an effective means of corrosion control. However, with adequate wet adhesion and low ionic conductivity, the lower the permeability of oxygen and water, the better protection the film will provide. See W. Funke in Surface Coatings, A. D. Wilson, J. W. Nicholson and H. J. Prosser, eds., Elsevier, London, 1988, p. 107.

High Performance Industrial Coatings

451

be remembered that all the other species present exert their effects, alone and in concert with the other components, on final film performance. The situation is further complicated by the fact that in most coatings the pigments and fillers represent a discontinuous phase which is mechanically coupled to the surrounding (usually) organic matrix to a greater or lesser degree, depending on the Inherent binder-filler interaction and the presence or absence of pigment surface treatment and dispersing or coupling agents. This gives rise to the all important consideration of pigment volume concentration and its relation to critical pigment volume concentration, a topic which has been treated exhaustively.^ The resulting paint film is of course really a complex composite. In fact, the mechanical properties of paint films as they relate to resistance to damage (of obvious interest in protective coatings) are probably best understood using methods first developed for structural composites, a relatively recent and promising approach.^ Even before considerations of final coating film properties, the details of film formation (the conversion of the free flowing liquid coating in the application/drying/curing stage to the final solid coating film) must be taken into account. The factors involved in the development of a dense, adherent, defect-free film during the coating application and drying process have been the subject of intensive study."^ There are a number of often competing phenomena which operate during application and drying: the response of the coating liquid to the shear forces generated by the application method; the flow and leveling of the coating liquid into a conformal film; wetting of the substrate, with displacement of air, water, or impurities from the substrate by the coating liquid along with the release of gases trapped or generated during the coating process; in the application of solution or dispersions, the evaporation of the carrier liquid with concomitant generation of concentration and surface tension gradients; with dispersions, the coalescence of the individual dispersion particles into a coherent film; with reactive systems (as high pert'ormance coatings often are), the interdiffusion of the reacting species, especially as the rate of diffusion compares to the rate of reaction, the rate at which the system approaches final Tg, and with dispersions, the rate of coalescence; and finally, the so-called "densification" phenomenon^, during which the last traces of volatile material evaporates, crystallinity or para-crystallinity develops, free volume decreases and the film assumes its final form. Obviously there are more occasions for forming film defects and for developing sub-optimum film performance then one cares to contemplate. Fortunately there is no lack of solutions provided by the judicious choice of coating components, especially the appropriate additives.® Though it is beyond the scope of this review, the interaction between the coating and the substrate must also be taken into consideration. It is well known that surface preparation is a key factor in optimizing coating performance. The removal of low surface energy materials, electrolytes, and existing surface corrosion are important not only to promote continuous film formation and initial adhesion but to remove species which contribute to such In-use effects as penetration by water caused by osmoticallydriven percolation (due to electrolytes); under-film corrosion (due to surface corrosion and other impurities); loss of adhesion (osmotic swelling or presence of a weak boundary layer due impurities or lack of initial wetting); and so on. Surface cleaning is

452

T.M. Santosusso

accomplished in a variety of ways, both mechanical and chemical. These include particulate blasting, scarifying, degreasing, and application of a conversion coating. This latter method converts the surface of metals to a very thin insoluble inorganic layer which both resists further oxidation and acts to provide a clean, uniform surface suited for reception of the protective coating. Following along this line of thinking leads to the concept of the primer-topcoat system, where the primer is designed particularly for its protective action In preventing surface attack, either as a passive barrier film, or a chemically sacrificial or inhibitive one, or both; and the topcoat provides both protection for the primer and contributes to the aesthetic properties. One perhaps obvious but typically overlooked practical element in coating performance is film thickness. All other things being equal (which admittedly they are usually not), a thick coating which remains both adherent and coherent during service will perform better than a thin one. (The qualifiers of adhesion and coherence are added since mismatches between modulus or coefficient of expansion between coating and substrate will tend to produce exaggerated effects- cracking or loss of adhesion duhng use - in thicker films.) The performance improvement is due to a number of factors, including the lower likelihood of film defects causing a discontinuity which exposes the substrate; the longer diffusion pathway for penetrants; and the greater film bulk which must be ablated before the substrate is exposed. In addition, while the protective nature of these coatings is being emphasized, the aesthetic considerations of gloss, color, resistance to dirt retention and overall appearance cannot be ignored. All in all, a tall order for a protective system that usually is not more than a small fraction of a millimeter thick. Finally, a relatively new but far-reaching consideration has been added to the list of requirements for the development of any coating, but one with particular relevance for high performance coatings: that of control of environmental, health and safety effects.^ From choice of raw materials, through manufacture, distribution, application and handling of waste streams to removal and replacement or recycling of the painted surface, "cradle-to-grave" lifetime Impact analysis is being applied to all coating systems. This has a notable effect on the sophisticated compositions associated with high performance coatings, especially as these changes affect coating efficacy and durability.® In the U.S., the heaviest reformulation burden has arisen from the control of the level and type of volatile organic compounds (VOCs) and hazardous air pollutants (HAPS) imposed by federal and state regulations. This one change has had the most comprehensive effects of any that have occurred over the last twenty-five years. Inevitably, it is in light of this change that developments in the typical binder systems used In high performance coatings are reviewed below. Epoxv Binders Epoxy-based systems represent the prototypical binder for coatings used in demanding applications. They are among the earliest developed and most versatile of the high performance coatings and have been thoroughly reviewed.^ They find their most use as primers and topcoats on structural steel and marine coatings; tank and drum linings; automotive and aerospace primers; concrete wall and floor paints; in flexibilized

High Performance Industrial Coatings

453

formulations as containment coatings; and as heat-cured formulations in coil and other OEM applications. The coatings typically exhibit low shrinkage, excellent adhesion, outstanding chemical and solvent resistance, good temperature resistance, and favorable curing charactehstics with no emission of volatile by-products. These properties are dehved from the combination of ring-opening crosslinking mechanism (little volume change during cure) and from the cyclic structures inherent in these coatings, with the resulting relatively high Tg and polar character. The weathering characteristics of the typical epoxies in thin film topcoats are not as desirable, especially on exposure to UV light, which manifests itself as discoloration and chalking. This response is associated with the aromatic structures which are derived from the epoxy-functional portion of the binder. Although improvements in external weathering of epoxy topcoats can be made, it is usually at the cost of limitations in other properties, and other more weatherable systems like the aliphatic polyurethanes are usually preferred for topcoat applications In the typical rigid epoxy, Impact and abrasion resistance are also somewhat compromised, except where special efforts are made to modify the system, as in containment coatings. Epoxy systems can be considered the paradigmatic two component coating. They consist of an epoxy-functional resin and a curative. The most important epoxy resins are those derived from the diphenol 2,2-bls(4-hydroxyphenyl)propane ("Bisphenol A") or other polyhydric phenols and epichlorohydrin;^° depending on molecular weight and type, these are available as either liquid or solid materials. The versatility of epoxy coatings dehves not only from the variations obtainable from the epoxy resins themselves but to an even greater extent from the type and number of curatives available.^^ These curatives can be generally classified into three types: multifunctional nucleophilic species containing active hydrogens (e.g., polyamines or polymercaptans) which undergo polyaddition reactions through opening of the epoxy ring; initiators which promote epoxy homopolymerization (e.g., boron trifluoride and its latent precursors); and hydroxy-reactive crosslinkers used with higher molecular weight epoxy resins having appreciable hydroxy functionality (e.g., polyisocyanates). The active hydrogen types are by far the most common, and their properties have considerable influence over the final coating characteristics. When the great variety of these curatives and the effects of modifications In stoichiometry are considered along with the diversity of diluents (reactive and non-reactive), catalysts, and other additives affecting the curing reaction, the various epoxy curing agents make for a profusion of possible coating types. Beyond that, the epoxy resins can be modified with resinous modifiers and curing agents to make hybridized materials, including polyester epoxies, epoxy-acryllcs, epoxy-phenolics and various blends with coal tar or furfural resins, vinyl resins, fluorocarbons, or silicones. Traditionally, epoxy coatings have been applied as solventborne systems. As with most other coatings, however, increasing importance has been given in recent years to low VOC and HAPS-free formulations, including high solids, 100% reactive and especially waterborne coatings^^. In specialty applications, 100% reactive radiation-curable coatings are used; crosslinking of acrylic and polyester powder coatings with epoxy-functional crosslinkers could also be considered a solventless epoxy application. The trend toward lower and lower concentrations of organic

454

T.M. Santosusso

volatiles \n response to regulatory pressures also appears to have inspired an aesthetically-driven demand for low odor coatings, applicators and consumers having realized that such systems were possible; no doubt this trend will continue. In addition to concerns about air quality, issues of worker exposure to coating components and their possible acute and chronic toxicity, Including mutagenicity and carcinogenicity, have become of Increasing importance. This has led, for example, to severely restricted use of the formerly common curing agent methylene bis(4-aminobenzene) (methylenedianiline or MDA). Such restrictions have sparked a surge of development of amine curing agent alternatives which are not based on aromatic diamines, the most widely used of which are the cycloaliphatics.''^ In contrast, the safety of Bisphenol A epoxy resins in highly sensitive applications like food contact coatings^"* is so well established that, given the regulatory climate, very little activity in changing the fundamental chemistry of the resin backbones is currently being considered. Most recent epoxy resin research is concerned with reducing the viscosity of existing resins for high solids systems or modifying existing resins for waterbased applications. A promising area of future research involves the use of incompatible polymer blends of epoxy and thermoplastic resins to produce improved coatings, where the heterogeneity of the system can be predicted using phase diagram analysis.^^ Polvurethanes Polyurethane coatings are used in approximately the same quantities as epoxy coatings in the U.S., which testifies to their utility. While not exhibiting the same degree of thermal and chemical resistance as the epoxies, they often can be formulated to meet the requirements of high performance applications. In addition, they typically show outstanding abrasion resistance and, when based on aliphatic isocyanates, they demonstrate excellent weathering properties. This makes them very well suited as topcoats, particularly when maintenance of appearance is an important factor. The aliphatic versions are often used as topcoats in primer-topcoat systems; In many demanding applications, an epoxy primer and a polyurethane topcoat are considered the ideal combination. They find wide use in a variety of industrial maintenance applications and more recently, as automotive clearcoats. The various forms of polyurethane resins have been used in coatings since the discovery of the utility of isocyanates in polymer systems in the 1940s, and the topic has been reviewed at length.^® Polyurethanes are formed by the reaction of multifunctional isocyanates and socalled active hydrogen compounds. These latter are not unsimilar to the protic species used as epoxy crosslinkers and include amines, hydroxy compounds, mercaptans and under special conditions, carboxylic acids, ureas, and urethanes themselves.* Additionally, the Isocyanates can undergo both self-reaction and reaction with the Strictly speaking, the term "urethane" refers only to the reaction product of a hydroxy compound and an isocyanate. The product of an isocyanate-amine reaction is a urea; an isocyanate-urea reaction, a biuret; an isocyanate-urethane reaction, an allophonate; and so on. Since all these reactions can occur simultaneously in the curing of the binder, the resulting coating tends to be called simply a "polyurethane". The separate reactions should be borne in mind, however, since the resulting polymer can have significantly different properties.

High Performance Industrial Coatings

455

urethanes or ureas formed in situ, particularly under the influence of catalytic species, with the formation of polymer networks which take their structure from the resulting cyclic trimers (isocyanurates), dimers (uretdiones) and branched compounds (allophonates and biurets). The isocyanates can also react with water with the formation of an intermediate carbamic acid which decomposes at use temperature into carbon dioxide and an amine. The amine will then react in a very fast step with more isocyanate to form a polyurea. This is the basis of the so-called moisture curing polyurethane coatings (see below.) The isocyanate-functional materials employed in coatings usually are limited in the amount of monomeric Isocyanate they contain, since many isocyanates are irritating and can be respiratory sensitizers. For this reason, the monomeric isocyanates are typically not used as primary coatings components. Instead, a number of higher molecular weight adducts are employed. In many cases, the degree of polymerization of the self-reaction of multifunctional isocyanates can be controlled so that low molecular weight, isocyanate-functional isocyanurates and allophonates can be made; these serve as convenient and safe alternatives to the monomer. Alternatively, diisocyanates can be adducted to multifunctional hydroxy compounds, with molecular weight again controlled (through stoichiometry) to yield relatively low molecular weight isocyanate-functional adducts. A major distinguishing characteristic of polyurethane coatings is whether they are based on aromatic or aliphatic isocyanates. Aromatic isocyanates tend to give tougher coatings with better solvent and chemical resistance than the aliphatics, while the aliphatics exhibit better control of reactivity and are used exclusively in applications involving exposure to natural sunlight, where their color retention Is superior to that of the aromatics which undergo severe photochemically-induced yellowing in exterior use. The active hydrogen compounds used as co-reactants with the isocyanates in polyurethane coatings are often oligomeric. These include hydroxy functional polyesters, polyethers, and polyacrylates ("polyols") and telechetic mercaptans and amines. The choice of the particular polyol used has an important effect on overall coatings processing and final properties and leads to a classification of polyurethane coatings based on the polyol component, for example polyester-based polyurethanes, polyether-based polyurethanes, and so on. Lower molecular weight polyfunctional active hydrogen compounds may also be use in combination with the main polyol to control reactivity and to modify properties, particularly through control of crosslink density. In addition, catalysts, which are usually added to control isocyanate-active hydrogen reactivity, can also promote self-reaction of the isocyanate or reaction with in situ urethane or urea groups, thus giving a very different reaction profile and different final coating properties compared to the same system without the added catalyst. Polyurethane coatings typically exhibit a unique combination of impact and abrasion resistance together with very good chemical resistance. This can be linked to the stability imparted by intermolecular hydrogen bonding and the self-reinforcing nature of the phase separated nature of many polyurethane networks.''^ In addition, the variety of chemical structures possible from variations In polyol backbone, crosslinkers, chain extenders, catalysts and isocyanates make polyurethanes among the most versatile of all coating binders in terms of final coatings properties. This versatility is

456

T.M. Santosusso

mirrored by the several forms polyurethane coating systems can take. As with epoxies, two component systems are the norm, the polyol and isocyanate components being packaged separately and not mixed until just before application. Traditionally, these have been solventborne systems, but recently two component waterborne systems have begun to appear.^® One component coatings can also be prepared using one of several formulation strategies. Moisture curable coatings take advantage of the isocyanate-water reaction mentioned above. An isocyanate-termlnated oligomer ("prepolymer") is formed by reaction of a polyol with a stoichiometric excess of diisocyanate monomer, further formulated and then stored protected from adventitious water. When this is applied to a substrate, the water normally present in the atmosphere reacts with the isocyanate to chain extend and crosslink the coatings through formation of urea linkages. Alternatively, "blocked" Isocyanates can be made by first reacting the isocyanate component of the coating with an active hydrogen compound that forms a thermally reversible urethane or urea bond (the urea derived from caprolactam is an example). The blocked isocyanate is stable in the presence of the polyol component but on heating undergoes irreversible reaction with the polyol and evaporation of the blocking agent. This approach can be used both in solvent systems and more recently in powder coatings.^® As an alternative to reactive systems, fully reacted low solids solvent-based urethane lacquers have been used in the past, but these have been largely replaced by water-based polyurethane dispersions ("PUDs")^°, though solventborne urethane modified drying oil formulations are available. Recent trends in polyurethane coatings, like epoxies, include environmental, health and safety issues, largely centered around the minimization of VOCs. In addition, there are concerns over the amount of monomeric isocyanates, especially in coating applications where respiratory exposure is an issue. The movement toward water-based systems to alleviate the former concern will probably continue. The latter topic has been addressed for some applications with the development of prepolymer systems which minimize the amount of monomer and while controlling the resin viscosity, even to the point of allowing the development of spray-applied one hundred percent reactive coatings.^^ Environmental issues aside, there has been a growing trend toward the development of polyurea coatings, formed from the reaction of multifunctional isocyanates and amines of moderated reactivity.^^ In some applications, these are beginning to rival epoxies and other highly crosslinked systems for corrosion resistance and durability. Melamine Resins Like epoxies, melamine resins offer a route to high Tg, highly crosslinked coatings with excellent overall properties. Unlike epoxies, and like the polyurethanes, they can be formulated into durable topcoats with good photochemical stability and weathering. They are also similar to polyurethanes In the sense that the melamine crosslinkers, which can be likened to the isocyanate crosslinkers of polyurethanes, will react with a variety of active hydrogen species, including many versions of hydroxy functional polyols; also like the isocyanates, they can undergo self-reaction. Additionally, their

High Performance Industrial Coatings

457

crosslinking chemistry is also very much influenced by catalytic species, especially strong acids. However, in contrast to epoxies and polyurethanes, almost all melamine coating systems require a bake cycle in order to achieve acceptable film properties. Another difference is that unlike most epoxy or polyurethane coatings, curing of the typical melamine results in the emission of volatile species (water or alcohols, with small amounts of formaldehyde) from the solid film, with possible implications for film quality. Despite these restrictions, melamine coatings have a long history of useful applications and have been the subject of numerous reviews.^^ They are used in a wide variety of OEM applications, including metal finishing and most importantly, automotive color coats. Melamine crosslinkers are the most important class (for coatings) of the socalled amino resins, derived from the reaction of formaldehyde with amine-functional materials. The melamine types are prepared from the reaction of formaldehyde with melamine (2,4,6-triamino-1,3,5-triazine) to form N-methylolated species. These are then further reacted with alcohols, typically methyl or butyl alcohol, to form the corresponding methylol ethers. Depending on reaction conditions, the methylolation step can lead to various degrees of methylol substitution and to dimerization and oligomerization. Similarly, the type and degree of etherification can vary. This gives rise to a number of commercially available crosslinkers with a variety of functionalities and reaction characteristics. When considered along with the large number of polyol coreactants available, including polyesters, acrylics, alkyds, epoxies and urethane oligomers. It will be appreciated that the melamines offer a wide choice of coating options. The stolchiometry of reactive components is usually determined on an empirical basis, since the degree of polyol-crosslinker reaction vs. self-condensation of the crosslinker and the desired degree of total crosslinking is difficult to determine in advance. The melamines may be employed either as one component or two component systems. In one component coatings, package stability is extended by incorporation of monofunctional low molecular weight alcohols and the use of thermally labile blocked acid catalysts such as amine salts of sulfonic acids. Typically, melamines have been employed as solventborne systems. The predominance of OEM applications with their engineering controls has mitigated concerns about solvent content to some degree, but VOC issues continue to be increasingly important in all coatings fields, and waterborne versions of the melamines are becoming more common. There Is an issue centered around formaldehyde emissions during and after coating application, and alternatives to the traditional alkoxylated melamines have been proposed^"*, those these have not been widely implemented. Other recent developments have been driven by the tendency of melamine-crosslinked coatings to undergo acid-catalyzed hydrolysis when subjected to acid etch conditions during weathering, such as are seen most noticeably with automotive coatings subjected to rain of low pH or to bird droppings. Improvements such as hybrid silane-melamine coatings have been developed and are used commercially^^; whether they will offer a general, long term cost effective alternative remains to be seen.

^58

T.M. Santosusso

Fluoropolvmers The chemical inertness, low surface energy, thermal stability, chemical and solvent resistance, resistance to both hydrophilic and oleophilic agents, and outstanding weathering characteristics of the fluorinated polymers are well known. This is due in part to the stability of the carbon-fluorine bond and to the very high molecular weight and crystalline nature of many of these polymers.^^ Indeed it is these factors that allow the fluoropolymers to be classified as high performance binders even though they are one of the few classes of linear, uncrosslinked polymers that fit this description. What epoxies, polyurethanes and melamines gain from crosslinking is replaced in the fluoropolymers by their typical fluorocarbon-like chemical and physical inertness. Every since the discovery of poly(tetrafluoroethylene) (PTFE) In 1938, the practical utilization of the fluoropolymers has had to strike a balance between maintaining the excellent properties of the unmodified polymer and accepting the processing difficulties associated with them, or modifying the resin by backbone changes or blending but having to accept a diminution of the protective film properties. For example, PTFE is insoluble in almost all solvents and has a sintering temperature in excess of 400°C, and while it is almost completely inert, cannot be routinely used in most Industrial maintenance applications. On the other hand, poly(vinylidene fluoride) (PVDF), with only half the fluorine substitution of PTFE, has a processing temperature on the order of 245°C and as an organosol coating is much more amenable to OEM metal finishing processes, particularly coil coating. These PVDF coatings exhibit outstanding weathering properties, though not nearly the heat or chemical resistance of PTFE, and are typically used on architectural fascia. Similar resins can be prepared by copolymerlzation of PVDF and hexafluoropropene.^^ Further compromises can be made by copolymerizing fluoroolefins, vinyl esters and other olefins to reduce polymer crystallinity. Although these polymers can be applied at relatively low temperature from solution or emulsion^®, their properties are not in the same class as PFTE. Additionally, functionalized fluoroolefin copolymers or telechetic fluoropolymer oligomers containing hydroxy groups can be Incorporated Into polyurethane coatings by crosslinking with isocyanates.^^ These should be considered as modified polyurethanes as opposed to fluoropolymer coatings. Similarly, other fluorinated polyols, siloxanes and epoxy resins can be incorporated into otherwise traditional coating systems, with a resultant improvement in properties.^° There have been a number of attempts to retain the desirable properties of fully fluorinated coatings resins while eliminating the difficulties associated with their lack of solubility and problems in film formation. Production of amorphous PTFE has been reported, for example.^^ Research into less highly fluorinated hydrocarbon polymers also continues.^^ Some of these can be formulated as low temperature-curing, waterbased systems.^^ However, until lower cost, more generally applicable solutions are developed, the use of fluoropolymers in maintenance coatings will probably remain limited to current applications.

High Performance Industrial Coatings

459

Silicone Resins All of the resin systems discussed above have been predicated on the chemistry of carbon-based polymer backbones. Silicone binders of the type used in coatings, on the other hand, are highly branched polymers of polysiloxanes, the backbone repeat unit being an organo-substituted (usually methyl and phenyl) Si—0 group*. Because of this "inorganic" character, they are noted for their high temperature resistance and resistance to chemical attack. Like the melamines, they usually require a bake cycle In order to achieve crosslinking, while like the fluoropolymers they are valued for their chemical inertness and weathering characteristics. Because of their highly crosslinked nature, they typically do not exhibit good impact resistance and have limited use over flexible substrates. Their use in coatings is of long standing and has been reviewed in a number of publications.^"* They find their most use in high temperature coatings such as those used on automotive mufflers and industrial heaters and chimneys. Pure silicone coating resins are supplied as functional oligomers where a small percent of the organic substltuent Is replaced with an hydroxyl or alkoxyl group. On heating, these undergo condensation reactions with the formation of Si—0—Si bonds which form the basis of the crosslinking chemistry. The rate of crosslinking is dependent on the substltuent groups and the presence of catalysts, usually organometallic compounds. The reactions tend to be relatively sluggish, and the polysiloxanes usually require relatively long bake cycles. In addition, a number of compromises must be made among the factors of desired degree of crosslinking, bake time and coating shelf life. Finally, the coatings have traditionally been solvent-based with relatively low solids content. Because of these limitations and the relatively high cost of the pure polysiloxanes, hybrid coating resins have been developed which are based on blends or copolymers of the polysiloxanes and carbon-based resins. These include polyesters, alkyds, acrylics and less importantly phenolics, epoxies and polyurethanes. Copolymerization can be accomplished via condensation of the hydroxyl groups on the base resin with the silanol of the reactive siloxane oligomer. The addition of the polysiloxane tends to markedly improve high temperature stability and, in the case of the modified alkyds, exterior durability. In addition, the hybrids usually require a less demanding baking cycle, and in some cases can be applied as ambient cure systems. They are typically used in coil coatings, cookware, tank coatings, marine applications and exterior architectural coatings. The most important advances in silicone coating systems are centered around the development of resins with lower VOC content. The usual strategy being employed Is modification of the resin so as to allow the formation of emulsion-based or waterreducible materials;^^ acrylic-silicone powder coating resins are also being devetoped.^^

* Silicate binders based on a pure unsubstituted Si—^O network from the hydrolysis of tetraalkoxy silanes or from condensation of alkali silicates will not be discussed here. They are important constituents of zinc rich primers and cementitious coatings but are truly inorganic in nature.

460

T.M. Santosusso

Other High Performance Coating Resins The number of organic polymeric materials outside of traditional binder materials that could be developed to fit the definition of a high performance coating resin is probably without end. However only a few systems have been identified which have been successfully applied in actual commercial coatings. A short discussion of a selection of these is presented below. Missing from the general discussion of high performance binders presented above is the topic of the chlorinated rubbers. In the past, these have been used extensively in marine, chemical processing, bridge and transportation applications. However, their lack of inherent thermal and photochemical stability, difficulties in production and availability only as relatively low solids solventborne systems make their use in current coatings problematic. Some attempt has been made to convert them to functional oligomers crosslinkable by isocyanates or melamines^^, but no general use of this technology appears to be emerging. Similarly, alkyd resins are well known in the industrial coatings area, but their lack of external durability calls into question their unmodified use in high performance coatings, especially in the face of modern alternatives. They are attractive in that their curing mechanism, relying as it does on the autoxidation of the drying oils on which they are based, allows for a convenient one pack approach to an ambient-curing coating. Modification with silicones or isocyanates does allow for an upgrading of their properties, as mentioned above. Styrene-unsaturated polyester resins can also be adapted for coatings purposes, although their main use is as the binder in fiberglass composites. They normally are applied as in-mold coatings (so-called "gel coats") where the oxygen inhibition of the typical peroxide-initiated cure is not a problem. For more typical coating applications, styrene-unsaturated polyesters alone are less suitable; their modification with allyl ether coreactants to reduce oxygen inhibition and preserve surface appearance is one alternative.^ They are a number of engineering thermoplastics which can adapted to use in coatings. These include polyphenylene sulfides^^ and polyimides'*^. Other similar polymers, which are not soluble in normal coating solvents, can be applied in a variety of thermal spray techniques.'*^ The traditional engineering thermoplastics can also be modified to provide crosslinking for greater thermal stability."*^ The use of polyfluorophosphazenes and polycarbosiloxanes for aerospace applications has also been reviewed."*^ Lastly, there has been a growing interest in the polyanilines, especially for corrosion control. This subject has been reviewed in several recent publications.'*'* Conclusions It has been said that the best way to predict the future is to invent it. That certainly seems to be the approach being taken by scientists and technologists In the coatings arena, and especially in high performance coatings. Even a cursory review of the specialist literature reveals a host of exciting possibilities for future development.

High Performance Industrial Coatings

461

Whether those approaches which will come to dominate will take the form of new resin systems, new crosslinking chemistries, hybrid coatings, new forms of coatings materials like powders or films, new application/curing methods like radiation or plasma - no one can say for sure at present. It is certain, however, that the next twenty-five years of development in high performance coatings will be at least as interesting as the last. Literature Cited ^ (a) C. G. Munger, "Resistant Coatings" in Kirk Othmer Encyclopedia of Chemical Technology, 3'"^ Edition, Vol. 6, John Wiley and Sons, pp. 455-481 (1979). (b) J. D. Kearne, ed., Steel Structures Painting Manual. Vol. I, Good Painting Practices, 2"^ edition, 1983 and Vol. II, Systems and Specifications, 6*^ edition, 1991, Steel Structures Painting Council, Pittsburgh, PA. ^ (a) G. P. Bierwagen and T. K. Hay," The Reduced Pigment Volume Concentration as an Important Parameter in Interpreting and Predicting the Properties of Organic Coatings" , Progress in Organic Coatings, Vol. 3, 1975, p. 281-303. (b) G. P. Bierwagen, R. Fishman, T. Storsved and J. Johnson, "Recent Studies of Particle Packing in Organic Coatings, Proceedings of the 24^ International Conference in Organic Coatings, Greek Society of the Paints Industry, 1998, p. 31-43. ^ See for example (a) Paint Research Association T"^ International Annual Research Colloquium, 15/16 June, 1998, The Paint Research Association, Teddington, England, (b) M. E. Nichols, J. L. Gerlock, C. A. Smith and C. A. Darr, "The Effects of Weathering on the Mechanical Performance of Automotive Paint Systems", Proceedings of the 24^ International Conference in Organic Coatings, Greek Society of the Paints Industry, 1998, p. 289-306. "* See for example, "Film Formation in Waterborne Coatings", T. Provder, M. A. Winnik and M. W. Urban eds., ACS Symposium Series 648, American Chemical Society, 1996. ^ L. C. E. Struik, Physical Aging in Amorphous Polymers and Other Materials, Elsesvier, Amsterdam, 1978. ® P. E. Pierce and C. K. Schoff, Coating Film Defects, Federation Series on Coatings Technology, Federation of Societies for Coatings Technology, Philadelphia, PA, 1988; Handbook of Coatings Additives, L. J. Calbo, ed., Marcel Dekker, New York, 1992. ^ For an excellent treatment of the evolution of environmental regulations, see S. C. DeVito, "Present and Future Regulatory Trends of the United States Environmental Protection Agency" in Proceedings of the 24^ International Conference in Organic Coatings, Greek Society of the Paints Industry, 1998, p. 105-116. ^ J. W. Martin, S. C. Saunders, F. L. Floyd, and J. P. Wineburg, "Methodologies for Predicting the Service Lives of Coating Systems", Federation of Societies for Coatings Technology, Blue Bell, PA 1966. ^ (a) T. F. Mika and R. S. Bauer, Epoxy Resins Chemistry and Technology, 2nd Edition, C. A. May, ed., Marcel Dekker, New York, 1988. (b) Waterborne and Solvent-Based Epoxies and Their End User Applications, P. Oldring, ed., SITA

462

T.M. Santosusso

Technology Ltd., London, 1996. (c) H. Lee and K. Neville, Handbook of Epoxy Resins, McGraw Hill, New York, 1967 (reissued 1982). 10, Ellis, ed., Chemistry and Technology of Epoxy Resins, Chapman & Hall, London, 1993. ^\a) J. B. Dickenson, "Curing Agents" in Epoxy Resins Chemistry and Technology, S'"* Edition, Marcel Dekker, New York, in press, (b) C. H. Hare, Paintindia, 46(12), 55-56, 58-60, 62-64 (1996). (c) C. H. Hare, Paintindia, 47(1), 51-52, 54-56 (1997). ^^ See for example, F. H. Walker and M. I. Cook, ACS Symposium Series 663, Technology for Waterborne Coatings, J. E. Glass, Editor, American Chemical Society, 1997. ^^ See for example, D. A. Dubowik, P. A. Lucas, A. K. Smith, (to Air Products and Chemicals) U.S. Pat. 5,280,091. '^ Title 21 Code of Federal Regulations (C.F.R.) § 175.300. ^^ v. Verkholantsev, "The Use of Phase State Diagrams to Design Polymer/Polymer Heterophase Coatings", Proceedings of the Twenty-Fourth International Waterborne, High-Solids & Powder Coatings Symposium, February 5-7, 1997, Department of Polymer Science, The University of Southern Mississippi and the Southern Society for Coatings Technology, p.446-457. ^® (a) G. Oertel, ed., Polyurethane Handbook: Chemistry - Raw Materials - Processing Application - Properties, 2nd edition, Hanser Gardner, 1993. (b) M. J. Husbands, C. J. S. Standen and G. Hayward, "Polyurethanes" in A Manual of Resins for Surface Coatings, P. Oldring and G. Hayward, eds., Vol. 3, Chapter 9, SITA Ltd., London, 1987. (c) J. H. Saunders and K. C. Frisch, Polyurethanes: Chemistry and Technology, Interscience, New York, 1974. (d) R. T. Wojcik and A. T. Chen, "Urethane coatings for Metal Substrates", Metal Finishing, April, 1994, p. 22-27. ^^ In addition to Ref. 15, see R. Blokland, Elasticity and Structure of Polyurethane Networks, Gordon & Breach Science Publishers, 1969. ^® (a) C. A. Hawkins, A. C. Sheppard and T. G. Wood, "Recent Advances in Aqueous Two-Component Systems for Heavy Duty Metal Protection", Progress in Organic Coatings, 32 (1997), p. 253-261. (b) C. R. Hegedus, A. G. Giliclnskl and R. J. Haney, "Film Formation in Aqueous Two Component Polyurethane Coatings", Journal of Coating Technology, 68 (1996) p. 51. (c) W. O. Buckley, "Zero VOC Two Component Waterborne Polyurethane Coating Systems", Modern Paint and Coatings, Oct. 1996, p. 81-86. ^^ A. Wenning, J-V. Weiss and W. Grenda, "Polyisocyanates Today and Tomorrow", European Coating Journal, 4/98, p.244-249. ^° I. Bechara, "Formulating with Polyurethane Dispersions", European Coating Journal, 4/98, p.236-243. ^^ S. L. Bassner, J. Kramer and T. M. Santosusso, "New Polyurethane Prepolymers for Ultra-Low VOC Plural Component Coatings" in Proceedings: Low- and No-VOC Coating Technologies: T"^ Biennial International Conference", U. S. Environmental Protection Agency, Office of Research and Development, October, 1998, Section 8, p. 70-82.

High Performance Industrial Coatings

463

^^ (a) D. A. Wicks and P. E. Yeske, "Amine Chemistries for Isocyanate-Based Coatings", Progress in Organic Coatings 30 (1997), p. 265-270. (b) D. J. Primeaux II, "100% Solids Aliphatic Spray Polyurea Elastomer Systems" In Polyurethanes World Congress 1991, Society of the Plastics Industry, Inc., Polyurethane Division and European Isocyanate Producers Association, September, 1991, p. 473-477. (c) T. Santosusso, D. J. Finocchio and J. H. Frey, "Oligomeric Diamine-Based Polyureas", Polyurethanes World Congress 1991, Society of the Plastics Industry, Inc., Polyurethane Division and European Isocyanate Producers Association, September, 1991, p. 329-336 ^^ (a) D. R. Bauer, "Melamine/Formaldehyde Crosslinkers: Characterization, Network Formation and Crosslink Degradation", Progress in Organic Coatings, 14, p. 193 ((1986). (b) W. J. Blank, "Reaction Mechanisms of Melamine Resins", Journal of Coatings Technology, 51, No. 656, p. 61 (1979). 24 A. Essenfeld and K-J. Wu, "A New Formaldehyde-Free Etch Resistant Melamine Crosslinker", Proceedings of the Twenty-Fourth International Waterborne, HighSolids & Powder Coatings Symposium, February 5-7, 1997, Department of Polymer Science, The University of Southern Mississippi and the Southern Society for Coatings Technology, p.246-258. ^^ I. Hazen, "Low VOC - Super High Solids Clearcoats", Proceedings of the 24^^ International Conference in Organic Coatings, Greek Society of the Paints Industry, 1998, p. 125-143. 26 (a) M. Howe-Grant, editor, "Fluorine Compounds, Organic (Polymers)" in Kirk Othmer Encyclopedia of Chemical Technology, 4*^ Edition, Vol. 11, John Wiley and Sons, 1994, p. 621-729. (b) W. W. Schmiegel, "Organic Fluoropolymers" in M. Hudlicky and A. E. Pavlath, Chemistry of Organic Fluorine Compounds II, A Critical Review, ACS Monograph 187, American Chemical Society, 1995, p. 1101-1118. (c) C. Tournut, P. Kappler and J. L. Perillon, "Copolymers of Vinylidene Fluoride in Coatings", Surface Coatings International, 1995 (3), p. 99-103. S. Gaboury, "High Performance Coatings: Novel VF2/HFP Copolymers", European Coatings Journal, June, 1997, p.624-626. 28 S. Kuwamura, T. Hibi and T. Agawa, "Waterborne Fluorinated Polyolefins in Coatings", Proceedings of the Twenty-Fourth International Waterborne, HighSolids & Powder Coatings Symposium, February 5-7, 1997, Department of Polymer Science, The University of Southern Mississippi and the Southern Society for Coatings Technology, p.406-418. (a) S. Turri, M. Scicchitano, G. Simone and C. Tonelli, "Chemical Approaches toward the Definition of New High-Solid and HIgh-Performance Fluorocoatings", Progress in Organic Coatings 32 (1997), p. 205-213. (b) V. Handforth, "Properties and Applications of Novel Fluoropolymer Resin", JOCCA, March 1993, p. 122. (a) J. F. Brady, Jr., "Properties Which Influence Marine Fouling Resistance in Polymers Containing Silicon and Fluorine", Proceedings of the 24^ International Conference in Organic Coatings, Greek Society of the Paints Industry, 1998, p.59-66 and references therein, (b) R. F. Brady, Jr., "Formulation and Field

464

T.M. Santosusso

Performance of Fluorinated Polyurethane Coatings" in Organic Coatings for Corrosion Control, G. P. Bierwagen, ed., ACS Symposium Series 689, American Chemical Society, 1998, p. 282-291. ^^ P. R. Resnick, Polymer Preprints, 31, 1990, p. 312. ^^ Anonymous, "New Development in Fluorinated Hydrocarbons", JOCCA, April 1990, p. 145. ^^ T. F. McCarthy, A. Thenappan, S. Murthy, K. Harris, R. Malec and D. Melick, "Poly(chlorotrifluoroethylene-vinylidene fluoride) Waterborne Coatings", Proceedings of the Twenty-Fifth International Waterborne, High-Solids & Powder Coatings Symposium, February 18-20, 1998, Department of Polymer Science, The University of Southern Mississippi and the Southern Society for Coatings Technology, p. 541-554. ^ (a) W. A. Finzel, "Properties of High Temperature Silicone Coatings", Journal of Protective Coatings and Linings, August, 1887, p. 38. (b) H. L. Cahn, "Silicones" in Technology of Paints, Varnishes and Lacquers, Chapter 14, C. R. Martins, ed., Robert Krieger Publishing Company, Huntingdon, NY, 1974. ^^ (a) J. W. Adams, "VOC-Compliant Silicones: Recent Developments", Proceedings of the 19^^ Annual Water-borne, Higher-Solids and Powder Coatings Symposium, University of Southern Mississippi, February 24-26, 1993, p. 302-313. (b) M. E. Gage and D. J. Gruike, "An Environmentally Compliant, High Performance, Heat Resistant Coating", 2&^ International SAMPE Technical Conference, 1994, p. 508-516. ^^ J. T. K. Woo, R. M. Marcinko, J. C. Reising and D. E. Miles, "Acrylic-Silicone Powder Coatings Resins", Proceedings of the Twenty-Fifth International Waterborne, High-Solids & Powder Coatings Symposium, February 18-20, 1998, Department of Polymer Science, The University of Southern Mississippi and the Southern Society for Coatings Technology, p. 231-242. ^^ S. F. Thames and Z. A. He, "Environmentally Compliant High Solids Chlohnated Rubber Coatings", Proceedings of the 19^^ Annual Water-borne, Higher-Solids and Powder Coatings Symposium, University of Southern Mississippi, February 24-26, 1993, p. 248. ^® M. J. Dvorchak and B. H. Riberi, Proceedings of the 16*^ International Conference on Organic Coating Science and Technology, 1990, p.1. ^^ L. R. Kallenbach and M. R. Lindstrom, American Chemical Society Polymer Preprints, 28 (1987) No. 1, p. 63-64. "^^ E. Sacher and J. R. Susko, Journal of Applied Polymer Science, 26 (1981) No. 2, p. 679-686. "^^ See for example, R. H. Henne and S. Schltter, "Plasma Spraying of High Performance Thermoplastics", Proceedings of the 8^" National Thermal Spraying Conference, 11-15 September, 1995, p. 527-531. ''^ F. W. Mercer, A. Easteal and M. Bruma, "Synthesis and Properties of New Alternating Poly(Aryl Ether) Copolymers Containing Cyano Groups", Polymer, Vol. 38, No. 3, 1997, p. 707-714.

High Performance Industrial Coatings

465

^^ J. I. Kleinan, Z. A. Iskanderova, F. J. Perez and R. C. Tennyson, "Protective Coatings for LEO Environments in Spacecraft Applications", Surface and Coatings Technology, 76-77, 1995, p. 827-834. "^"^ (a) T. P. McAndrew, S. A. Miller, A. G. Giliclnski and L. M. Robeson, "Polyaniline in Corrosion-Resistant Coatings" in Organic Coatings for Corrosion Control, G. P. BienA/agen, ed., ACS Symposium Series 689, American Chemical Society, 1998, p. 396-408. (b) S. Jasty and A. Epstein, "Corrosion Prevention Capability of Polyaniline (Emeraldine Base and Salt): An XPS Study", Journal of Polymeric Materials Science and Engineering, 72,1995, p. 595-596. BIBLIOGRAPHY There are a number of publications which those interested in high performance coatings will find valuable. Some of these are listed below. C. H. Hare, "Protective Coatings. Fundamentals of Chemistry and Composition", Technology Publishing Company, Pittsburgh, PA, 1994. Z. Wicks, F. Jones and P. Pappas, "Organic Coatings Science and Technology", WileyInterscience, New York, Vol. I, 1992 and Vol. II, 1994. S. Paul, "Surface Coatings Science and Technology", Wiley-lnterscience, New York, 1985. J. D. Kearne, ed., "Steel Structures Painting Manual. Vol. I, Good Painting Practices", 2"" edition, 1983 and Vol. II, "Systems and Specifications", 6*^ edition, 1991, Steel Structures Painting Council, Pittsburgh, PA. Federation Series on Coatings Technology, Federation of Societies for Coatings Technology, Philadelphia, PA, 1986 to present. B. Ellis, ed., "Chemistry and Technology of Epoxy Resins", Chapman & Hall, London, 1993. G. Oertel, ed., "Polyurethane Handbook : Chemistry - Raw Materials - Processing Application - Properties", 2nd edition, Hanser Gardner, 1993. D. Scantlebury and M. Kendig, eds., "Proceedings of the Symposium on Advances in Corrosion Protection by Organic Coatings 11, Proceedings Volume 95-13, The Electrochemical Society: New Jersey, 1995. R. A. Dickie and F. L. Floyd, eds, "Polymeric Materials for Corrosion Control", ACS Symposium Series No. 322, ACS Books, Washington, DC, 1986.

466

T.M. Santosusso

C. G. Munger, "Corrosion Protection by Protective Coatings", National Association of Corrosion Engineers, Houston, TX, 1984. National Research Council, "Coatings for High Temperature Structural Materials: Trends and Opportunities", National Academy Press, 1996. J. H. Lindsay, ed., "Coatings and Coating Processes for Metals", ASM International, 1998. J. Edwards, "Coating and Surface Treatment Systems for Metals: A Comprehensive Guide to Selection", National Association of Corrosion Engineers, Houston, TX, 1997. Y. Saito, B. Onay and T. Maruyama, eds., "High Temperature Corrosion of Advanced Materials and Protective Coatings: Proceedings of the Workshop on High Temperature Corrosion of Advanced Materials", North-Holland, 1992. L.H. Lee, ed., "Adhesives, Sealants and Coatings for Space and Harsh Environments", Polymer Science and Technology, Vol. 37, Plenum Publishing Corporation, 1988. L. Pawlowski, "The Science and Engineering of Thermal Spray Coatings", John Wiley and Sons, New York, 1995. INTERNET SITES If there has been one change in the last twenty-five years, it has been the information technology supporting all of science and technology, including high performance coatings. The most rapid change has been the emergence of the Internet as a source of information. Some sites of interest are listed below. Coatings Raw Material Suppliers Aabor International - Produces organic & metallic pigments for color applications in printing inks, paints and coatings, plastic concentrates and dispersions. http'V/aarbor. com/ Air Products and Chemicals - Manufactures VOC-compliant resins, including waterborne emulsions and polyurethanes; epoxy curing agents; surfactants. http://airproducts. com/ Akzo Nobel - VOC-compliant waterborne coatings, high solids and powder coatings, adhesives, surfacing materials, printing inks, toners, and associated products and polymers. http://www.akzonobeLcom/ Albright & Wilson - Operates internationally in three business areas: phosphates, phosphorus derivative, acrylics and surfactants, http://www.albright-wilson.com/ BASF - Resins, surfactants, and coatings, http://www.basf.com/

High Performance Industrial Coatings

467

Bayer. Performance Products Division - Coatings and specialty products, including resins, curatives, organic dyes and pigments. http://www. bayerus. com/about/business/chemicals/products. html Beniamin Moore - Resins and coatings, http://www.benjaminmoore.com/ Cargill - Resins, http://www.cargill.com/ Ciba Specialty Chemicals - Manufacture and marketing of innovative specialty chemicals including resins, and additives, http://www.cibasc.com/ Color Corporation of America - Pigments, http://www.ccofa.com/ Creanova inc. - Resins, curatives and additives, http://www.creanovainc.com/ Degussa - Additives and pigments, http://www.degussa.com/ Derakane - A branch of Dow Chemical's Composite Group dedicated to epoxy vinyl ester resins, http://www.derakane.com/ Dupont - Major product areas include resins and pigments, http://www.dupont.com/ Elf Atochem North America, Inc. - Searchable site for resin information, http://www.elfatochem.com/ Engelhard - Business groups include pigment and additives, http://www.engelhard.com/ Henkel Corporation - Organic specialty chemicals product groups including additives, curatives, and resins, http://www.henkel.com/ ICI Surfactants - Additives, http://www.surfactants.com/ Kentucky-Tennessee Clay - Produces ball clay, kaolin and feldspar. http://www. ceramics, com/kt/ Kronos - Pigments, http://www.nlink.com/kronos Lubrizol Coating Additives - Additives for coatings, paints and inks. http://www. lubrizol. com/ Lvondell Petrochemical - Producer of high value-added specialty polymers, color concentrates and polymeric powders, http://www.lyondell.com/ Micro Powders - Technically advanced micronized wax additives. http://www. micropowders. com/ Millennium Chemicals inc. - specialty chemicals, http://www.millenniumchem.com/ National Starch and Chemical Company - specialty synthetic polymers http://www. nationalstarch. com/ PPG Industries - Coatings and resins, http://www.ppg.com/ Reichhold Chemicals, inc. - Online catalog of specialty polymer and adhesives listings. http://www. reichhold. com/ Rhodia Inc. - Resins, curatives, and coatings, http://www.rp.rpna.com/ Rohm and Haas - Resins and additives, http://www.rohmhaas.com/ Sun Chemical - Manufactures organic pigment products in a variety of physical forms. http://www. sunpigments. com/ Union Carbide - Producer of ethylene oxide and ethylene glycol (resins and additives). http://www. unioncarbide. com/ Valspar - Resins, colorants, and coatings, http://www.valspar.com/ Vianova Resins - Produces acrylic, epoxy, polyurethane, polyester and alkyd resins. http://www. vianova-resins. com/ W. W. Grainoer - Additives - online catalog, http://www.grainger.com/

468

T.M. Santosusso

Wacker-Chemie - Additives - polymers and silicones. http://www. wacker. de/english/0. htm Organizations and Consortia ASM International - A society for materials engineers who distribute technical information through electronic media, publications, conferences, training programs and chapter activities. http://www. asm-intl. orgAndex. htm ASTM - Developed and published over 10,000 technical standards, which are used by industries worldwide, http://www.astm.org/ Coating Alternatives Guide (CAGE) - Information about coating alternatives, namely solvent-borne, water reducible, powder, and other alternatives. http://cage. rti. org/altern. htm Corrosion. Protective Coatings and paint Resources on the Internet - Direct link listing of technical articles and papers; organizations and societies; publications; U.S. and foreign manufacturers, http://www.execpc.com/-rustoleu/coatings.htm The Electrochemical Society - Society for electrochemical and solid state science and technology. Publications, books, technical meetings and awards http://www. electrochem. org/ Federation of Societies for Coatings Technoloov (FSCT) - Trade organization with the monthly technical publication, http://www.coatingstech.org/ Industrial Paint & Powder - Online magazine, informational resource for producers of OEM paint and powder coatings and the finishers who apply them. Problem solver, supplier directory, listing of coming events and feature articles. http://www. ippmagazine. com/ Inter-Societv Color Council - Non-profit organization aiming to promote the practical application of coatings technology to the color problems arising in science and industry. http://www. iscc. org/ National Association of Corrosion Engineers (NACE) - Technical society dedicated to reducing the economic impact of corrosion, promoting public safety, and protecting the environment by advancing the knowledge of corrosion engineering and science. http://www. nace. org/ National Coil Coaters Association (NCCA) - Industrial trade organization representing the coil coating industry, http://www.coilcoaters.org/ National Metal Finishing Resource Center - A comprehensive environmental compliance, technical assistance and pollution prevention information source available for the metal finishing industry and technical assistance providers. http://www. nmfrc. org/ National Paint and Coatings Association (NPCA) - Trade association representing the paint and coatings industry in the U.S. http://www.paint.org/ Organic Coatings Forum - A site on coatings information sponsored by Elsevier Publishing, http://www.elsevier.com/locate/coatingsforum

High Performance Industrial Coatings

469

Paint & Coatings Industry Magazine - Online publication serving the manufacturer and formulator of paint, coatings and printing inks, http://www.bnp.com/pci/ Paint Coatings.Net - Related articles, directories, tradeshows, and product news. http://www.paintcoatings. net/pcnmain. htm PaintExpo - Partnership between NPCA and PCI magazine created an on-line "trade show" concept. Provides information on companies (manufacturers, chemical suppliers and distributors), product information, industry news and calendar of key industry events. http://www. paintexpo. com/ The Paint Research Association - Based in the UK, contains various links on research and technical information on paints, inks and adhesives. http://www.pra. org. uMndex. htm PaintWebs - With over 2,000 listings and hundreds of links for the paint & coatings industry; coating manufacturers, coating consultants, distributors, coating educators, equipment suppliers, related organizations, coating publications, and raw material suppliers. http://www.jvhltd. com/paintwebs/default1. html PowderCoating.COM - Powder coating resource for suppliers, shops, network forum or equipment, http://www.powdercoating.com/ Protective Coatings worldWIDE - An information resource for the protective coatings industry. Publications, news and information, and a coatings and equipment Directory. http://www.protectivecoatings.com/ Structural Steel Painting Council (SSPC) - Trade association; publications, conferences, and training, http://www.sspc.org/ Usenet Group for Coatings - Internet news. news:sci.chem.coatings Universities Eastern Michigan University Coatings Research Center - Research areas include: rheology and application, cross-linking, analysis and characterization, adhesion, corrosion, and design and modeling, http://www.emich.edu/public/cot/crc.html Eindhoven University of Technology - Research programs include: Moisture curable sealants, Powder coatings, Waterborne paints, Organic/inorganic hybrid coatings. Selfstratifying coatings, Finishing in mold, Adhesion of coatings on metals, and Historical paints. http://www. chem. tue. nl/coatings/ Massachusetts Institute of Technology. Department of Materials Science and Engineering - Current research activities include: Ceramics and Glasses; Composites and Joining; Device Materials, Thin Films; Economics of Materials; Environmental Interactions; History of Materials; Metals; Polymers and Biological Materials; and Theory and Modeling. http://www'dmse. mit. edu/ North Dakota State University. Department of Polymers and Coatings - General research areas: corrosion protection of coatings, surface and interfaclal

470

T.M. Santosusso

chemistry/spectroscopy in coatings, molecular level adhesion, scanning probe microscopy of coatings, cross-linking chemistry and cross-linked film properties, stabilization and rheology of dispersions and coatings, and new techniques to analyze VOC emission. http://www. ndsu. nodak. edu/ndsu/nupoly/poly_coat/poly_coa.htm University of Missouri-Rolla Coatings Institute - A variety of coatings research areas, including waterborne systems, pigments and additives, conductive coatings, rheology control agents, ultrasonics and microwaves in coatings, and transparent composites. http://www. umr. edu/-coatings/ University of Southern Mississippi. Department of Polymer Science - Research areas include: Polymer Science and Chemistry, Polymer Synthesis and Characterization, Polymer Physical Chemistry Polymer Reaction Engineering, Polymer Characterization and Engineering and Heterogeneous Polymer Materials. http://www. psrc. asm. edu/main. html