Barrier primer

Non-corrosion-inhibiting primers Corrosion-inhibiting primers Inorganic barrier primers Rubber to metal primers... 

Primers for protective coatings may be divided into three broad classes based on the mechanism of substrate protection barrier primers that function by preventing the ingress of moisture and electrolytes, primers that protect the substrate galvanically in the presence of electrolytes, and primers that contain electrochemical inhibitors to passivate the substrate. Each of these approaches requires a distinct primer film structure due to the different mechanisms of protection. 

Fig. 9. Barrier primer film structure as a function of PVC. From ref. [70].

Uses Binder, film-former in paints (printed circuit board coatings, coil, container, corrosion protection, marine, metal, plastics, primers, sealers, tarp, wire enamels, wood varnishes, barrier primers), printing inks (gravure, flexo, screen printing), primers (adhesion promotion/corrosion protection), heat-sealable lacquers, two-pack paints, resinous/polymeric food-contact coatings, reactive resin in two-pack systems, e.g., crosslinked with melamine/phenolic resins Features Forms flexible, odorless, tasteless films thru solv. evaporation ... 

Chem. Descrip. Carboxyiated styrene-butadiene iatex Uses S/B for trade saies coatings, interior vapor barrier primer seaiers and fiatwaii paints... 

Synonyms Carboxylated styrene-butadiene copolymer Uses Nonwoven binder for textiles In Interior vapor barrier primer sealers and flat wall paint binder for paper coatings food-pkg. adhesives/ paper... 

S/B, interior vapor barrier primer Dehysol R Resorcinol-formaldehyde resin... 

Penetrating primer Barrier primer Pigmented stucco primer... 

Heavy Metal Free Water-Borne Barrier Primer... 

The need to identify replacements for chromate-based technologies has also resulted in the development of alternatives to resin-based corrosion-inhibiting primers. These are primarily inorganic barrier coating techniques, such as sol-gel processes, which may or may not include corrosion inhibitors. These are discussed in a later section. 

The primary function of a coating is to act as a barrier which isolates the underlying metal from the environment, and in certain circumstances such as an impervious continuous vitreous enamel on steel, this could be regarded as thermodynamic control. However, whereas a thick bituminous coating will act in the same way as n vitreous enamel, paint coatings are normally permeable to oxygen and water and in the case of an inhibitive primer (red lead, zinc chromate) anodic control will be significant, whilst the converse applies to a zinc-rich primer that will provide cathodic control to the substrate. 

Whenever the operation to be performed involves the potential to cause the initiation of the propellant, explosive or pyrotechnic (PEP) component(s) of a munition item, the APE is either operated by remote control, with the operator behind a protection wall or barrier, or it is enclosed in a protective barricade or operational shield. Barricades or operational shields are designed to protect personnel and assets from the effects of blast overpressures, thermal effects or fireball, and fragments result from the initiation of PEP components, such as the fuze, primer, propelling charge, burster, etc. 

Salt spray test. The model coatings of Table I are of the high solid type used in automotive top coats. Their primary function is not corrosion protection since this is first of all a matter of phosphate layer, electrocoat and/or primer. However, the topcoats may contribute to corrosion protection by their barrier function for water, oxygen and salts. Therefore their permeability is important as one of the factors in the corrosion protection by the total coating system. We feel that a salt spray test of the model coatings directly applied to a steel surface is of little relevance for their corrosion protection performance in a real system. 

On the other hand it is advantageous to choose a primer esdiibiting optimal wet adhesion and simultaneously optimal barrier properties. 

The most common forms of flexible packaging are the blister package and the pouch. A blister package usually consists of a lid material and a forming film. The lid material is usually a laminate, which includes a barrier layer (e.g., aluminum foil) with a print primer on one side and a sealing agent (e.g., a heat-sealing lacquer) on the other side. 

Some primers will improve the durability of the joint by protecting the substrate surface area from hydration and corrosion. These primers suppress the formation of weak boundary layers that could develop during exposure to wet environments. Primers that contain film-forming resins are sometimes considered interfacial water barriers. They keep water out of the joint interface area and prevent corrosion of the metal surfaces. By establishing a strong, moisture-resistant bond, the primer protects the adhesive-adherend interface and lengthens the service life of the bonded joint. 

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