Primers, general surface protection

Primers developed to protect treated surfaces before bonding are generally proprietary formulations manufactured by the adhesive producer to match the adhesive. These usually consist of a diluted solution (approximately 10% by weight) of the base adhesive in an organic solvent. Like the adhesive formulation, the primer may... 

Primers. The primer is a universal component of all anticorrosive coatings and is considered to be one of the most important element of a protective system. A good primer generally provides the ability to stifle or retard the spread of corrosion discontinuities such as pinholes, holidays, or breaks in the film. To perform satisfactorily they must themselves adhere well to the base metal or any surface conversion coating that might be present. They should also contain an adequate concentration of a leachable inhibitor, where this is considered an important feature of the protection system, and this is usually a chromate pigment. The primary functions of a primer are... 

Primers usually require solvent evaporation and several curing steps before the adhesive or sealant can be applied. Adhesive primers are usually not fully cured during their initial application. They are dried at room temperature, and some are forced-air dried for 30 to 60 min at 65°C. This provides a dry, nontacky surface that can be protected from contamination and physical damage by good housekeeping practices until the substrate is ready to be bonded with an adhesive. Full primer cure is generally achieved during the cure of the adhesive. 

Primers protect prepared surfaces from the environment and may also be designed to promote adhesion. These are recommended by manufacturers for some adhesives. They are generally in the form of a liquid which is applied to the prepared surface and dried before applying the adhesive. Some contain a weak soiution of adhesive or bond-promoting substances, in some speciai forms of adhesive the primer also acts as a cure catalyst. 

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