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This article has been withdrawn as it was published elsewhere and accidentally duplicated. The original article can be seen here: 10.1108/eb007088. When citing the article, please cite: P. Kresse, (1979), “Influence of inert pigments on the anti-corrosive properties of paint films: Part 2”, Anti-Corrosion Methods and Materials, Vol. 26 Iss: 2, pp. 16 - 20.

3.2. Water permeation without water accumulation at the pigment/binder interface From the anti‐corrosion point of view it is of course preferable to use pigments which do not accumulate water at the pigment/binder interface when the film is soaked with water. Then water permeation decreases with rising PVC; the anti‐corrosive action should reach an optimum close below (CPVC. In practice such a behaviour is not very often observed. Since there is nearly always a small amount of water accumulated at the pigment/binder interface, a decrease of the degree of corrosion with the PVC until nearly reaching the CPVC can very seldom be noticed.

Because of rationalisation and demands for improved quality, the surface coatings industry makes ever‐increasing demands for micronised pigments. Micronised pigments permit quicker dispersion and increased output, coincident with decreased production costs. Such factors as the superior dispersibility of micronised pigments have frequently been mentioned, and it is not easy to quote new aspects of this. Therefore, this article will primarily cover other technical advantages of micronised iron oxide pigments‐advantages hitherto neglected in favour of the main advantage, better dispersibility.

After considering the most important variables on which various forms of colloidal instability can depend, some important principal aspects of this phenomenon should be discussed.

The overall concept of permeability in paint films has been reviewed by Boxall and von Fraunhofer [Paint Manufacture, 45, November (1975) p. 14] who point out that as a result of their research the efficiency of anti‐corrosion pigments is closely related to water permeability in the paint film. Indeed, pigments like basic zinc chromate are only cabale of inhibiting substrate corrosion when in contact with water. This raises an interesting question relative to the effectiveness of anticorrosive pigments in highly water‐resistant films. Of course, as the authors point out, all films have a degree of permeability. No doubt this permeability increases as the film ages and, accordingly, the anticorrosive pigment may become more effective as the film ages and loses some of its protective properties.

This work aims to study the corrosion protection of laboratory‐prepared micaceous zinc ferrite (MZF) pigment in anticorrosive paints for steel.

Acrylic‐modified alkyd coatings, based on MZF pigment, micaceous iron oxide (MIO) and zinc ferrite (ZF) pigments, were prepared at different pigment volume concentrations “PVCs” to the critical pigment volume concentrations “CPVCs” ratio, which denoted hereafter by A. Scanning electron microscope, weight loss measurements, water vapour transmission (WVT) and immersion in 3.5 per cent salt solution as well as physico‐mechanical properties were performed to evaluate the paints anticorrosive performance.

WVT and corrosion protection can be affected by the PVC/CPVC ratio for all systems. At any particular PVC, the barrier property of the pigment was the main factor affecting the WVT and corrosion protection. MZF pigment protected the carbon steel physically through barrier action and chemically by the reaction with the acidic acrylic‐modified alkyd resin to produce soaps which passivate the substrate.

Novel MZF paint could be used with optimum percentage in anticorrosive paints for steel protection especially in humid and coastal regions.

The Leeds Exhibition. Now that summer is virtually over the season of trade exhibitions is about to commence and one of the first, and undoubtedly most important, of these is our own Corrosion and Metal Finishing Exhibition and Symposium (October 15–18). It is an unfortunate fact that London‐based industrialists always seem to get the best of major exhibitions but this year, by virtue of a bold experiment, the North and Midlands will be getting their own major Corrosion Exhibition at Leeds. We are certain that we shall not upset our Yorkshire readers if we state that the exhibition is in a more natural home in Leeds than it would be in London. The atmosphere in Leeds is certainly more corrosive than in West London.

The purpose of this work was to investigate the possibilities for the exploitation of the powder by‐product of oxygen convertor slag from the ferronickel industry as pigment in anticorrosive non‐toxic paints. The chemical composition of the powder shows a large content of Fe₃O₄ and a high value of pH, two features favouring its use in anticorrosive paints. Paints with this powder, either unrefined or processed, as a pigment and chlorinated rubber resin were produced and tested by the following methods: half‐cell potential, mass loss, chloride diffusion and EIS. The results indicated that protection of steel was achieved to a satisfactory level, especially with the processed material.

Ion‐exchange clays containing sodium such as bentonite and montmorillonite have the ability to exchange their cations. Few studies conducted with this type of ion‐exchange pigments are not conclusive about their anticorrosive efficiency. The present research aims to address the study on the anticorrosive efficiency of this type of pigments in chlorinated rubber paints. Sodium‐bentonite was exchanged with Zn, Sr and Zn‐Sr to be applied on low carbon steel specimens and study the anticorrosive performances of these new ion‐exchanged bentonites (IEBs) in anticorrosive paint formulations.

The new pigments were characterised using scanning electron microscopy (SEM) and X‐ray fluorescence (XRF) to determine the CEC (cation exchange capacity) of the different exchanged cations. Evaluation of the ion‐exchanged and Na‐bentonite pigments using international standard testing methods (ASTM) was estimated. Paint systems manufactured with these ion‐exchange pigments have been subjected to adhesion, accelerated corrosion laboratory tests, and EIS in order to assess their anticorrosive behaviour.

The results of this work revealed that the ion‐exchange bentonite (IEBs) pigments showed high anticorrosive performance that can be arranged as follows: Sr‐bentonite was better than Zn‐Bentonite and both were better than the double Zn‐Sr‐bentonite indicating an antagonism behaviour between the two cations when present together.

These pigments can be applied in other polymer composites, e.g. rubber and plastics as reinforcing agent and fillers.

These prepared pigments are environmentally friendly pigments which impart high anticorrosive behaviour to paint films with great economic savings.

Croda Resins Ltd. Crabtree Manorway, Belvedere, Kent DA17 6BA have been working in the area of water thinnable polymers for paint and ink for some years. The products which have resulted from this continuing work are:—