Thermosetting powder coating

Thermosetting coating powders are applied mainly by electrostatic spraying and dominate the market. The annual growth rates worldwide are about 10%. Total... 

Table 3.4. Production of thermosetting coating powders in 1995 classified according to binder types...

Although other processes are described, thermosetting coating powders are produced exclusively by the extruder process. This method is employed because it is the cheapest and the most widely applicable and flexible it allows large plants to be supplied with material of consistent quality. Production with extruders includes the following steps ... 

The main reasons for the steadily increasing use of thermosetting coating powders (see Section 3.4.1) are as follows ... 

Table 3.10. Uses of thermosetting coating powders (1995) expressed as percentage of production...

The vast majority of thermosetting coating powders are prepared by melt muting. Some thermoplastic powders are also produced by this method but most are manufactured by the dry-blend process as shown in Figure 1. Production methods based on spray drying from solution (86) and precipitation from solution (87) have been evaluated but never achieved commercial success because of difficulties in solvent and/or water removal from the powders. Many types of coating powders are still manufactured in small batches, eg, 50-1500 kg, due to differences in color or chemistry, where chemical processes are not economical. 

Thermoplastic polyesters achieved some commercial success during the mid-1980s however, these were eventually replaced by nylon coating powders in functional coatings and thermosetting polyester powders in decorative appHcations because of lack of any unique characteristics or price advantages (see Polyesters, thermoplastic). 

The worldwide market for coating powders increased at an aimualized growth rate of 12—13% in the 1980s. Moreover, worldwide coating powder usage for thermosetting decorative powders is expected to increase to 332,000 t by 1992, a 264% increase over the quantity sold in 1984 (75). A significant factor... 

Table 4. 1989 World Market Distribution of Thermoset Decorative Powder Coatings ...

Table 3.4 summarizes the consumption of thermosetting binders used in various regions. The epoxy-polyester systems predominate over polyester-trisglycidyl iso-cyanurate and epoxy systems. The consumption of thermoplastic coating powders, particularly those used in the fluidized-bed and flocking processes, is substantially lower than that of thermosetting powders (Table 3.5). Their production does not show a comparably significant growth rate.

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