Rapid growth in the 1950s and 60s (continued)

Nitrocellulose lacquers declined in the car industry after 1960, but they became the dominant clear finish for timber. An Australian manufacturer, Wattyl, developed in the fifties a hot spraying technique to apply thicker films at faster line speeds.

Polyurethanes were pioneered during and after the Second World War by Bayer (West Germany) and their further development was taken up by a number of major companies. Bayer also dominated isocyanate reactive prepolymers for paints, but Australian resin and paint manufacturers developed many hydroxy functional polyesters and acrylics required as co-reactants for wood and metal coatings.

Polyesters of the unsaturated type were introduced in the 1950s by resin manufacturers including Monsanto and Reichhold, and paint manufacturers, including Wattyl and Mirotone supplied finishes for articles such as TV cabinets.

Water based house paints represented a major departure from the distempers described earlier. However, the first such paints in the 1940s, based on casein emulsions, did not enjoy popularity for long, because they were prone to fungal attack. In 1953 the first latex emulsion paint was introduced by Glazebrooks. It was based on a styrene butadiene composition and was followed by a progressive trend towards polyvinyl acetate latices.

A step change in technology occurred in the 1960s, when chemists succeeded in transferring acrylics know-how into water based systems. Rohm and Haas in the USA had done most of the research on acrylic latices for water based, gloss exterior house paint. It was, however, Australian paint companies which took and maintained the lead role, world-wide, in applying this technology. They were helped in this by the established Australian tradition of protecting the outside of houses with high gloss finishes, while in most other countries matt finishes were in demand. These acrylic latices were extremely durable; but to achieve the brushing properties necessary two requirements had to be met: firstly, the latex particles had to be smaller and of a narrower range of sizes than that used for matt finishes; secondly, a thickener was needed to attain brushing consistency, without, however, causing pseudo-plasticity, poor flow and brush marks.

Dulux[137] developed such a thickener. Conventional thickeners for latices such as the cellulosic types usually are in a separate phase.

The new thickener was hydrophobic (averse to the water phase) and associated with the latex and pigment particles. The result was that the paint was particularly easy to apply and retained its non-flocculated condition in the can.

Australian Academy of Technological Sciences and Engineering