PAINT MANUFACTURING

Organic coatings are composed of pigments suspended in a vehicle. The vehicle or carrier consists primarily of a resinuous of driers, plasticizers and stabilizers as required. As the paint film dries, these vehicles changes from a liquid to the solid film by one or more of several mechanisms.

1. Evaporation of Solvents.

2. Oxidation (of a drying oil).

3. Polymerization through application of heat, addition of catalyst, or combination of reactive components.

The pigments contribute such properties as inhibitions of a metal surface (red lead & zinc chromate), reinforcement of the film, stabilization against deterioration by sunlight, controlled chalking (titanium oxide) and colour clear coating (varnishes, lacquers & shellac) are not pigmented.

Inorganic coatings such as the zinc silicates also may be though of as a pigment suspended in a vehicle. In this case, the pigment con consists of metallic zinc dust, and the vehicle is a blend of water soluble silicates.

Terminology sometimes is confecesing. “Paint” usually refers to materials applied primarily for their decorative effect and any protection received is of secondary importance. The term coating or “protective coating” on the other hand generally is received for use when protecting is the primary consideration.

The alkyd resins form the largest groups of synthetic resins available to the paint industry. Alkyd finishes in general shows good gloss and gloss retention. These resins are employed in stroving enamels quick drying paints, stoving coatings in conjunction with amino resins, marine paints etc.

Among the resins used, it has been found that 90% of alkyd produced are handled in one of these ways to produce some type of paints varnishes, or lacquer for industrial and home consumption. So the scheme is prepared mainly on the production of the modified alkyd resins though production of phenolic and meleic resins are also considered. Alkyd resins are classified according to the amount of oil and phthalic anhydride present in the alkyd.

Enamel paint is paint that air-dries to a hard, usually glossy, finish, used for coating surfaces that are outdoors or otherwise subject to hard wear or variations in temperature; it should not be confused with decorated objects in “painted enamel”, where vitreous enamel is applied with brushes and fired in a kiln. The name is something of a misnomer, as in reality, most commercially available enamel paints are significantly softer than either vitreous enamel or stoved synthetic resins, and are totally different in composition; vitreous enamel is applied as a powder or paste and then fired at high temperature. There is no generally accepted definition or standard for use of the term enamel paint, and not all enamel-type paints may use it.

Typically the term “enamel paint” is used to describe oil-based covering products, usually with a significant amount of gloss in them, however recently many latex or water-based paints have adopted the term as well. The term today means “hard surfaced paint” and usually is in reference to paint brands of higher quality, floor coatings of a high gloss finish, or spray paints. Most enamel paints are alkyd resin based. Some enamel paints have been made by adding varnish to oil-based paint.
Although “enamels” and “painted enamel” in art normally refer to vitreous enamel, in the 20th century some artists used commercial enamel paints in art, including Pablo Picasso (mixing it with oil paint), Hermann-Paul, Jackson Pollock, and Sidney Nolan. The Trial (1947) is one of a number of works by Nolan to use enamel paint, usually Ripolin, a commercial paint not intended for art, also Picasso’s usual brand. Some “enamel paints” are now produced specifically for artists.

The short oil alkyds are of two types:

1. Non-drying type
2. Drying types

The short oil non-drying alkyds contain, coconut, castor oil or similar saturated fatty acids. They are used as plasticizers in cellulose nitrate lacquers and baking enamels combine with amino resins. They find uses for very hard and tough finishes like automobiles refrigerators, washing, machines, home freezers and other metal finishing users.

The short oil drying alkyds contain tall oil, fatty acids like soybean, dehydrated castor and linseeds oils. Alkyds have utility in industrial backing finishes. They are also used as metal primers. Medium oil alkyds are the most versatile of the alkyds family. They have excellent gloss durability and flexibility. The medium oil alkyds find use in air drying of baking enamels, metal decorative coatings, machinery paints furniture finishes, metal primers and also in roller coating finishes.

Long oil alkyds find wide applications in structural steel finishes marine paints, interior and exterior architectural enamels and for oleo-resinous varnishes. Very long oil alkyds dry slowly but have good brushing properties and also durability.

Phenolic and maleic resins, are mainly modified with resins which is an important component in surface coating media. Principal uses for these resins include air drying industrial finishes, floor varnishes and also for hard gloss paint media.

Maleic resins excel in initial colour and colour stability to phenolic resins but inferior to phenolic resins in water alkali resistance.