Paints surface finish characteristics

Especially in the automotive industry, the appearance of a painted surface becomes more and more important. An automotive finish is a multi-layer system - E-coat, Primer, Topcoat, clear coat. Each layer can have several characteristics that influence the appearance of the final finish. The two major objectives of the paint manufacturer are to optimize the physical/chemical properties of the coating as well as to achieve an optimum paint appearance (wet, smooth look). The end use of the paint (trucks versus prestige cars), then determines the necessary degree of achievement. 

Finishes are also described by the function of the paint. A primer is used to coat the original surface. Its major functional property is good adhesion. Protection against corrosion is an especially important characteristic of metal primers. Hiding is a secondary function. 

The characteristics of fluoropolymers are summarized in Table 1. Thermal and chemical resistance is in general with most of plastics, elastomers and perfluorinated membranes. Weather resistance with the outdoor durability for more than 20 years is specific for fluorinated paint resins. Surface properties such as water and oil repellency are provided by acrylic polymer-based textile finishes and coatings with long-chain per-fluoroalkyl groups. Electrical properties as well as a low refractive index are important for optoelectronics applications like optical fibers. 

Most physical properties of a particulate system are ensembles or statistical values of the properties from their individual constituents. Commonly evaluated particle geometrical properties are counts, dimension (size and distribution), shape (or conformation), and surface features (specific area, charge and distribution, porosity and distribution). Of these properties, characterization of particle size and surface features is of key interest. The behavior of a particulate system and many of its physical parameters are highly size-dependent. For example, the viscosity, flow characteristics, filterability of suspensions, reaction rate and chemical activity of a particulate system, the stability of emulsions and suspensions, abrasiveness of dry powders, color and finish of colloidal paints and paper coatings, strength of ceramics, are all dependent on particle size distribution. Out of necessity, there are many... 

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