Waterborne technology: its greatest limitation is your imagination

Sandy Morrison , Member of SpecialChem Technical Expert Team

Introduction

Waterborne paints have a long and successful history in certain niche applications (see this month's editorial), but the twin issues of environmental legislation and the low cost of water as a solvent have encouraged their much wider use. Today's waterborne systems can - in the same way as their early predecessors - offer application and performance advantages over solventborne technology, but now in a much wider range of situations.

How have paintmakers dealt with the problems inherent in waterborne technology? Are these limitations fundamental and unavoidable - or are 'fundamental limits' mainly created by a lack of imagination? This column attempts to answer these questions, while the accompanying editorial looks at market statistics and the (very) early history of waterborne coatings.

Breaking the boundaries

It has been estimated that in western economies, as much as 90% of the volume of DIY paints sold are now waterbornes. Outside this field, the picture is a mixed one. Waterborne coatings successfully dominate the market for interior wall paints and exterior masonry coatings, but elsewhere they must compete with high solids, solventless and radiation curable systems as environmentally friendly, regulation-compliant coatings.

Insert any one of the three pictures of houses in this section No caption required

Some problems have been regarded as inevitable when using waterborne coatings - but some which appeared to be insoluble turn out not to be. So what are the prospects for breaking out of these supposed boundaries?

Foaming v wetting: an end to a paradox?

Two of the best known and almost universal problems which have limited the

performance of waterborne paints are foaming and poor adhesion. Both arise from the same cause: water has a far higher surface tension than any other solvent used in coatings. Solutions have tended to be in conflict with each other, since highly effective surfactants that will promote adhesion are often excellent foam generators, whereas defoamers may cause surface wetting problems and many are slowly deactivated during storage of the wet paint by the surfactants.

Recent developments in molecular engineering have created various types of complex surfactants which are able to enhance both foam control and substrate wetting. What all these materials have in common is that two or more surfactant moieties are firmly bound into the same molecule, and the defoaming effect takes place at a molecular level, rather than being affected by the particle size of the defoamer. Storage stability is also enhanced by the fact that defoaming no longer depends on maintaining an optimum particle size. The simplest types, called 'gemini surfactants' comprise two surfactant molecules bound together by a spacer molecule. Other companies offer more complex 'star' molecules and dendrimers.

Improving substrate penetration and bonding

Also related to the issue of substrate wetting is the limited penetration of emulsified resins into porous substrates, though the first cause of this is that emulsion particle size is much larger than that of the molecules themselves. Waterborne alkyds, with their finer particle size and slow oxidative drying, are frequently incorporated into emulsion paints to improve the penetration of woodfinishes, though this is at the expense of drying time.

One approach to defeating the particle size problem is a substituted styrene-acrylate resin in which the emulsion particles incorporate an aliphatic hydrocarbon which is a true solvent for the resin. As the water evaporates, what is in effect a high-solids solvent-borne paint is formed. Coatings based on this product are reported to penetrate twice as deep into porous masonry as conventional acrylic emulsions, and as a result, provide improved adhesion.1 The system does not require additional coalescing solvents and paints can be formulated with a VOC content of 75 g/l or less.

Alkyd/acrylic hybrids have been developed in which the alkyd resin core is protected during storage by an acrylic layer, but which allow the (water-insoluble) alkyd to penetrate wooden substrates after drying and cure by oxidation. Current versions of this technology appear to suffer from the unfortunate combination of limited wet-edge time but extended hard-dry times. However, improved drying has been claimed for a modification in which secondary hydroxyl groups are present in the ester linkages of the alkyds.

If you cannot improve penetration, a useful alternative is to increase adhesion. Isocyanates are capable of developing a covalent bond with hydroxyl groups on the surface of wood and this process can improve the adhesion of wood primers. However, when isocyanates are added to waterborne systems, they immediately begin to react and so applying this concept to waterborne primers presents some difficulties. Some experiments have been carried out using an application system with continuous isocyanate addition to minimise these problems. Panels coated with this primer showed improved adhesion (especially wet adhesion). This improvement was retained when the primer was overcoated, but after prolonged ageing, differences in performance were less

marked. Thus, the isocyanate addition reduces the risk of early damage to the paint on the coated articles.2

'Insoluble' coalescence problems: 1- achieving high gloss

While disruption of film formation can occur when coatings are deposited from solution, it is usually easily avoided by appropriate formulation. The matter becomes much more difficult when dealing with waterborne dispersion resins. As is well known, coalescence of the individual particles requires them to have a soft surface so that the particles will fuse together at the surface, a requirement which conflicts with the general desire for the coating to have a hard and tack-free surface. Standard solutions to this problem include core-shell particles (discussed in more detail below), volatile coalescents, reactive diluents and the use of crosslinking resins.

Theoretical studies have shed light on further problems. If surface drying proceeds rapidly, a surface 'skin' of partly coalesced particles may form which inhibits further evaporation and leads to irregular film formation. The concept of the Péclet number (used in fluid dynamics) has been applied to this situation. Its value increases with the viscosity of the continuous phase, film thickness, evaporation speed and particle size. At low values, the particles are able to diffuse rapidly enough (due to Brownian motion) to ensure uniform drying; at high values they will be drawn towards the surface, causing premature skinning.3

Further work by the same researchers showed that the presence of 'free' surfactant and other low MW water-soluble materials can interfere with smooth film formation even at temperatures well above the Tg of the resin.

Thus it should be no surprise that high gloss air-drying waterborne finishes are rarely able to match the gloss levels of traditional alkyds, and if they do, the haze or distinctness-of-image is usually inferior. A recent study provides further light on this problem.

Fundamentally, the apparent gloss is dependent on surface roughness and overall refractive index of the film. Attempts to reduce the surface roughness of gloss emulsions to match that of alkyds were unsuccessful, even with low pigmentation, high film thickness and variations in rheology. Electron microscopy revealed a key difference: the surface of the alkyd film was a continuous resin layer, whereas particles of titanium dioxide protruded above the surface of the emulsion paint. Application of an unpigmented layer of waterborne resin produced gloss levels matching those of an alkyd, and in this situation, the gloss was affected significantly by the refractive index of the binder (styrene acrylic having a higher RI and gloss than pure acrylic).

However, few people will be willing to adopt this basecoat/clearcoat concept in decorative applications. A water-based alkyd-acrylate resin has now been developed which forms a continuous resin layer during drying and is able to match the gloss and distinctness-of-image of traditional alkyds.4

'Insoluble' coalescence problems: 2 - the road to zero VOC

The fundamental requirement for film coalescence to occur is that the surface of the

polymeric particles must be sufficiently soft to merge into one another as the film contracts. On the other hand, a hard film surface is necessary to resist damage, dirt pickup and solvent penetration.

If paints are formulated using 'standard' dispersions without coalescents, the low Tg which used to achieve coalescence results in soft films, poor resistance to staining and dirt pickup and an increased risk of film formation defects. Yet in practice several different ways have been found to minimise or avoid this problem and produce good film properties in single-pack air-drying near-zero VOC paints.

A simple but limited approach is to use emulsions such as VAE (vinyl acetate-ethylene) copolymers which are naturally hydrophilic. Water itself acts as a 'cosolvent' during film formation, so that for a given minimum film forming temperature (MFFT), the Tg of VAE emulsions is significantly higher (by about 8°C) than that of styrene-acrylic emulsions. Similarly, in the case of polyurethane dispersions, the presence of water within the emulsified particles themselves assists in achieving coalescence.

Several coalescents have been developed with sufficiently high boiling points and low volatility to ensure that they are not legally classed as VOCs - though the question of whether they are released into the atmosphere over a very long period is hard to answer.

• 2,2,4-trimethyl-1,3-pentanediol (isobutyric acid, 1-isopropyl-2,2-dimethyltrimethyl ester) has a boiling point of 280°C, which means that it is legally not classed as a VOC, but may be so classed in some environmental standards.

• Archer RC is a zero-VOC coalescent for waterborne inks, paints and sealants. The material is based on propylene glycol monoesters of sunflower and corn oil fatty acids. It crosslinks during drying rather than evaporating, adding to the resistance properties of the coating. Archer claims the product calls for little or noreformulation, since its HLB value is similar to that of the common coalescent TMB (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate).

• Cognis markets EFC-100, a propylene glycol mono-oleate with a very high boiling point as a coalescent. The company claims that although the product remains permanently in the film, it has little effect on hardness and provides scrub, stain and blocking resistance that are at least as good as standard volatile coalescents. In addition, because the product is very hydrophobic, it modifies the rheology of the system, and in some cases may increase gloss.5

A further approach is to make the coalescent and/or part of the polymer system radiation curable. Camphorquinone is an effective photoinitiator for curing coatings under natural sunlight, due to its high absorption at around 450 nm. It has been shown that some radiation-curable acrylate monomers can be used to replace normal cosolvents with little or no reformulation. After curing in sunlight, paints containing no other cosolvents showed hardness values up to 30% higher than those of a conventional emulsion paint with cosolvents.6

Polyurethane dispersions have traditionally been manufactured using N-methyl pyrrolidone as a solvent in order to keep the viscosity at a manageable level during the polymerisation. The NMP remains after the polymer is emulsified and contributes to VOC levels. Manufacturers are seeking to avoid the use of NMP entirely because of

concerns over its toxicology. Alternatives include the acetone process (where it is possible to strip off this high-boiling solvent afterwards) or the use of acrylic monomers as solvents (forming urethane/acrylic hybrids).

Two-pack waterborne PU systems can similarly be produced which need no cosolvent, by adding hydroxy-functional reactive diluents when forming secondary dispersions of hydroxy acrylates as the polyol component of the system.

Corrosion protection

At first sight, the use of waterborne coatings for corrosion protection appears perverse; water is, after all, a key factor in creating corrosion. Nevertheless, one of the great success stories for waterborne coatings has been the development of the cathodic electrodeposition process, now the near-universal method of protecting vehicle bodies against corrosion. It provides a coat of controllable and fairly uniform thickness on both visible and inaccessible parts of the bodywork with very little use of solvents or waste of paint.

After initial pretreatment such as phosphating, the body of a vehicle passes through a tank of waterborne coating while an electric current 'plates' the coating onto the metal. The coatings are cured by stoving, after rinsing off excess coating which has not been consolidated into the film. Modern electrocoating formulations are able to provide effective protection without use of the lead chromates which traditionally served as anticorrosive pigments.

In more general anticorrosive markets, progressive improvements have been made. A report from the USA notes that tests of systems based on acrylic and styrene-acrylic resins in the early 1980s gave poor results, whereas tests in 2000-2002 gave good results for waterborne acrylics (outperforming waterborne epoxies and a polyurethane) and indicated that the best waterborne acrylic formulations were now competitive with solventborne acrylics and epoxies.7

Outperforming solventborne systems

Some of the coatings with the highest resistance to exterior weathering are based on polyvinylidene fluoride (PVDF), but established PVDF technologies for both liquid and powder coatings require stoving. These coatings contain about 70% PVDF and 30% acrylic resin and owe their high performance to the formation of an interpenetrating polymer network (IPN) on stoving. Waterborne PVDF emulsion coatings are now available, which are said to achieve similar results without stoving. The key to this technology is that the emulsion particles themselves must contain IPNs; emulsions based on core-shell particles will only perform effectively after stoving.8

Unwanted-effect coatings

Reactions between water and aluminium pigments, which can readily blow the lid off a paint container, can be due to hydrogen generation. Effect pigment suppliers now offer 'protected' grades which resolve the problem; and it does not arise with pearlescents. This problem can be considered as solved, with waterborne metallic basecoats being widely used in automotive coatings, but the author can recall some interesting

laboratory-scale failures in the early days of this technology.

A more difficult problem which produces unwanted effects is the staining due to bleeding-out of coloured compounds in the wood. The kiln-drying process helps to 'set' resinous materials but has little effect on materials such as tannins. Since these are water-soluble they (and other staining materials) are more problematic with waterborne coatings that with solventborne ones. A range of solutions has been examined, and in general improvements can be achieved by incorporating barrier pigments (aluminium flake) or reactive pigments (zinc compounds). A number of more sophisticated approaches have also been developed for waterborne coatings, relying on the use of cationic materials to immobilise the tannins.

A waterborne cationic epoxy primer has been developed which provides good resistance against tannin staining over wood and also over nicotine stains when applied over existing interior paintwork. The binder was formulated as an epoxy-amine adduct neutralised with an organic acid in order to make it water-soluble, then water-insoluble epoxy resin was added under agitation to increase the molecular weight. This was applied as a clear primer to maximise its barrier properties and protected the subsequently applied acrylic emulsion paint against staining.9 A similar concept has been applied successfully using styrene-acrylate emulsions. Amine groups are incorporated into the polymer, and neutralised with volatile organic acids to produce the coating.10

In addition to improving the physical barrier properties of the coating, improvements can be obtained by incorporating functionalities such as urethanes which will crosslink with the extractable components of the wood.11

This approach is highly desirable when using coatings whose cure may be affected by high levels of extractables (a known problem with radiation curable systems). It has been claimed that the use of a waterborne primer containing a waterborne dispersion of crosslinkable urethane and low levels of a suitable crosslinker (preferably an aziridine rather than an isocyanate) provides more effective stain sealing than a corresponding solventborne coating.12

Good stain blocking has also been achieved by the addition of exfoliated fine particle size hydrotalcite, using an anionic dispersing agent for the exfoliation so as to produce material with a very high surface area that has a cationic exterior. Additions of as little as 0.5% hydrotalcite have been shown to be effective, when added to a self-crosslinking dispersion resin formulation.

Breaking the solids content barrier

Normally, the solids content of waterborne emulsions is limited by instability as the solids content increases. While there is no regulatory need to reduce the content of water in a coating, increasing the solids content allows drying times to be reduced and higher film build coatings to be applied.

A distinctive form of hybrid resin technology allows very high solids waterborne coatings to be produced, the resin itself having a solids content of 70-80%. The concept is to produce a conventional emulsion polymer (normally acrylic) and then to disperse a

second, different resin at a much smaller particle size within the free water of the dispersion. By careful process control, it is possible to achieve a much lower viscosity/solids curve than for normal emulsions.

These resins have been found to provide faster drying, good substrate penetration and adhesion. Water resistance is good, and initial natural exposure trials indicate that the coatings should have a long useful life.13 These systems have initially been developed for exterior wood coatings, but their use for masonry coatings is being examined. Products based on this technology were commercialised in 2003, with a VOC content of below 25 g/litre.

Key waterborne coating technologies

Having considered some of the once-insoluble challenges which waterborne technology has successfully overcome, it is also useful to briefly examine some of the key technologies which are allowing waterbornes to develop yet further towards challenging and surpassing solventborne technologies.

Core-shell technology

The most significant general concept used to enhance the properties of waterborne coatings is that of core-shell technology. Many researchers have confirmed that a better balance of blocking resistance and low-temperature film formation can be achieved by using either core-shell polymers with a soft shell or mixtures of hard and soft emulsions rather than homogeneous copolymerised emulsions with the same overall monomer composition.

The morphology of heterogeneous emulsion particles can in fact take on many more forms than a simple core-shell structure or a random mixture of components in each particle. If an initial homopolymerisation is carried out, followed by addition and polymerisation of a second monomer, the distinctness of the boundary between the core formed in the first polymerisation and the shell formed in the second depends (among other factors) on the extent to which the core particles are crosslinked during polymerisation. If, on the other hand, the different polymers are mixed before dispersion so that composite particles are produced, separation of the polymers will be driven mainly by differences in hydrophobicity and surface tension.

Multi-lobed ('raspberry') and other more complex structures can be produced. The composition of the monomer feed can also be continuously varied during the polymerisation process to yield 'gradients' of composition from core to shell. An extension of this technology is to use inorganic nanoparticles to form the core or as part of the core.

"Core-shell" particles may have a range of very different

morphologies

A recently announced development is the production of emulsions which incorporate within the particles monomers that have an affinity for pigments. This helps to ensure that pigment particles remain unflocculated and are more uniformly distributed in the paint film. It is claimed that these emulsions give improved corrosion and abrasion resistance as well as the increased opacity and higher gloss which would be expected.14

This construction can be created readily, since a mixture of hydrophobic and hydrophilic materials dispersed together will tend to form droplets in which the hydrophobic material is encased by the more hydrophilic one - especially if the latter has surfactant-like properties.

Polyurethane dispersions and their hybrids

Waterborne polyurethane dispersion (PUD) coatings were first introduced in the 1970s and are now produced in non-reactive physical drying, 2-pack and UV curable forms. The properties of the final coating can be varied from very hard to extremely flexible. The backbone of a PUD may be made from many different materials, including polyesters, polyethers and polysiloxanes, but recently a number of authors have claimed that a better overall balance of properties can be obtained (at higher cost!) by using a polycarbonate backbone.

Their high cost can be reduced by mixing with other resins. Simple blending of polyurethane dispersions (PUDs) with acrylic emulsions provides useful coatings with a good cost/property balance, but much better performance can be obtained by preparing true urethane/acrylate hybrids. Two types are known:

• Type 1: Acrylic monomers are added to an existing PUD and polymerised in the mixture.

• Type 2: Initial urethane polymerisation, which normally requires a solvent to maintain a low viscosity, is carried out, using part of the acrylate monomer in place of a solvent. Dispersion occurs automatically when the prepolymer is added to water. Chain extension can be carried out at this point to increase the MW, followed by acrylate polymerisation.

In either case, the individual emulsified particles contain intimate mixtures of the two

polymers. Frequently, the particles are swollen and plasticised by water molecules, which assists coalescence.

Although PUDs are supplied as fully crosslinked high MW resins which need no curing agent, the addition of a polyisocyanate will provide harder films and improved chemical resistance. (If the PUD has no hydroxyl functionality, the isocyanate simply self-crosslinks by moisture curing.) Another way to produce tougher films is to incorporate acrylate functionality, add a photoinitiator and cure under UV irradiation. Such coatings have the advantage of having a low crosslink density, making them much more flexible than standard UV curable coatings, while also producing reasonable hardness and mechanical properties in shadow areas which are not fully cured.

Self-crosslinking PUDs have been developed which have good storage stability, but which undergo a rapid carbonyl-amine crosslinking reaction during drying, if the coatings are formulated with a volatile amine as pH stabiliser.15

Extending the scope of epoxies

Type I waterborne epoxies, developed in the 1970s, use liquid epoxies emulsified by water-soluble polyamide curing agents. In the later type II systems, the curing agent is mixed into a dispersion of solid epoxy which contains some solvent. Each has strengths and weaknesses. Type I coatings form mixed emulsion particles at the outset and require little cosolvent. They produce hard coatings, but with insufficient flexibility and impact resistance for use over metal substrates. Type II systems dry more rapidly and are more flexible, but usually require high levels of cosolvent as it is necessary for the curing agent to become dispersed within the epoxy emulsion particles.

Recently, an epoxy resin has been developed which has a very low particle size in dispersion and a relatively high fraction of low MW material, both of these factors making coalescence easier to achieve and producing a system which is intermediate between Type I and Type II.16 Initial tests indicate that it is possible to produce anticorrosive primers, gloss finishes and concrete coatings with good performance at very low cosolvent contents.

Dow has developed a range of fine particle size (below 1 µm) epoxy dispersions produced by a patented mechanical dispersion process which are solvent-free and stabilised by nonionic surfactants which are epoxy functional and so crosslink into the final coating. The very fine particle size ensures homogeneous curing when used with a water-soluble curing agent, and high gloss and resistance properties can be obtained.

The range of applications open to these coatings has been further extended by the development of hydrophobic polymeric amines which provide increased colour stability as well as improved acid resistance.

The furniture industry

As noted in this month's editorial, the furniture industry represents an important but difficult market for waterborne coatings. A major European project known as the COST

E18 initiative has been operating for several years, with the objective of improving the performance, durability and environmental profile of coated wood structures. Two issues have led to the furniture industry being closely studied in COST:

• The industry is highly fragmented, with as many as 60 000 SMEs in Europe that may have difficulty in carrying out detailed research or making major investments in new plants;

• Natural wood is used in high quality furniture, and is one of the most difficult substrates to deal with in terms of maintaining the appearance of traditional finishes while retaining good physical and chemical resistance properties.

While the use of waterborne coatings in the industry rose from 5% in 1997 to 16% in 2003 and the use of radiation-curable coatings also increased, the industry has a major problem in trying to comply with the European VOC emission targets overall.

A COST report from early in 2006 indicates that by that time, waterborne technologies had improved to the point at which single-component coatings could replace nitrocellulose, and waterborne UV and PU coatings their solventborne counterparts. An investigation of energy consumption in drying indicated that the increase in power was not as great as might be imagined, though care had to be taken in selecting the most appropriate oven drying system.17

Cleaner and greener: miscellaneous applications

Finally, it may be interesting to consider some of the byways of waterborne coatings technology, once again illustrating the point that we never know what is possible until it has been done. Dow Chemical has recently developed a method by which solvent-free very fine particle size dispersions of polyolefins can be produced (these materials cannot be produced via emulsion polymerisation and have very high melting points). Coalescence requires heating of the applied film to the melting point of the polymers, though no crosslinking reactions are involved. These materials can be applied by many industrial processes and are expected to prove useful in applications such as textile coatings, carpet backings and lamination adhesives and can also be foamed.18

HMG paints (UK) recently introduced a waterborne grass-marking paint for use in creating promotional signage at sports events. Paint Away has been formulated to resist the inevitable British rain, provide strong colours which will show up well on TV broadcasts, yet can be dispersed by a special cleaner which does not harm the grass.

Electrolube (UK) has developed a waterborne conformal coating (for protection of electronic components) which eliminates the low flashpoint solvents often used in these materials. It meets the high demands for resistance to solvents, humidity and wide temperature operating range, though it does not provide as high a level of insulation resistance as standard solventborne types. It can also be soldered through without releasing toxic gases.

Radiation curing coatings may be considered a 'competitor' for waterborne coatings, but it should be noted that solventless UV systems have a number of limitations which can

be resolved by the use of waterborne versions. Waterborne radcure coatings avoid the need to use high levels of monomer diluents, which in turn allows films to be produced with lower crosslink density, less shrinkage on cure and better substrate adhesion. Oxygen inhibition may be reduced, and controllable matting is much more easily achieved.

But, no matter how good the performance of a paint, no matter how environmentally friendly it is, waste is inevitably produced and must be disposed of. Various schemes have been used to recycle waste decorative emulsion paint in particular, ranging from simply collecting the paint and offering it to charitable and community associations to blending it and attempting to recycle it into new paint. Recently, however, researchers at Rutgers University (USA) have shown that it is possible to blend waste paint solids with either HDPE or PMMA (methyl methacrylate). Aside from a loss of transparency, the paint addition had little effect on the properties of HDPE and acted as a toughener and flexibiliser for the PMMA.19

Waterborne limits drift with time

As this review has I hope shown, waterborne technology has broken down most of the apparent limits to its wider adoption, and known technologies are even now taking these developments further.

The ultimate and intractable limit is that water is a slow-evaporating solvent with an inconveniently high freezing point. Drying time has been speeded up by (for example) producing solids contents higher than the theoretical limit. So who will be first to introduce a waterborne coating with an MFFT below zero? Don't say it will never happen; think about how to make it happen!

References

1. F Duval, A Fream, Polym Paint Colour Jnl, Jan 2004 pp 36, 38 2. J G Nienhuis, M A J Akkerman, Surf Coat Intl B, June 2002 pp123-129 3. J L Keddie et al, Surf Coat Intl A, 2004/02 pp 70-73 4. R Dersch et al, paper presented at Nürnberg Congress, May 2007 5. A A Khan et al, PRA Waterborne & High Solids Coatings Conference 2006,

paper 15 6. D Burget, 7th Nürnberg congress, 7-8 April 2003 paper VI.1, pp 73-83 7. S L Chong, Y Yao, US Dept of Transport report FHWA-RD-03-032 (online) 8. K A Wood, Europ Coat Jnl 09/2005 pp 48, 50-53; Arkema press release, June

2006 9. R Feola, M Gobec, China Coat Jnl, 2/2007 pp 26, 28-33 10. J Fischer, W van Drunen, Europ Coat Jnl, 2007/05 pp 168-170 11. D Twene, D Mestach, Surface Coat Intl A, Nov 2004 pp 384-389 12. USP 7 157 120 13. J H Olsen, PRA Woodcoatings Congress Oct 2004 paper 41; USP 6 277 910 14. M Bleuzen et al, Europ Coat Jnl, 2007/5 pp 144,146, 148-9 15. A van den Elshout, Surface Coatings International A, A06, July 2003 pp 229-232 16. Ancarez AR 550 resin 17. M Roux et al, PRA Waterbone & High Solids Coatings Conference 2006, paper 3 18. C F Diehl, PRA Waterbone & High Solids Coatings Conference 2006, paper 6;

SpecialChem online seminar, 21 June 2007 19. M Drukenbrod, SpecialChem, 22 March 2007