Post 357 – by Gautam Shah
Large number of items and components are available in ready to use state with a suitable finish. These products require no extra treatment or coating, before or after the installation. The industrially finished items are class apart from finishes applied on a site, after assembly or erection.
An industrial plant offers streamline production system, in a batch or a continuous fashion. Industrial plant-based surface finish is a process integrated with production and highly articulated one. It is invariably conducted in a controlled environment and observance.
Site applied surface finishes, substantially consist of architectural coatings, and are multi surface applications (general purpose or GP systems). Other on site applications, but not forming part of architectural range, include Road marking paints, Marine paints, and re-application systems. On a site coatings are employed in a wide range of weathers and in open environments. Architectural coatings, for ‘drying’, rely mainly on moisture evaporation, induced polymerization, and in few instances on catalyst curing (popularly known as ‘two-pack’) systems. Architectural coatings are applied, chiefly on masonry, and than to lesser extent on wood and metal surfaces.
Industrial finishes are very specific systems, formulated for a particular substrate, object shapes, sizes, pre-treatments, method of application and drying or curing cycles and schedules. As a result, complex surface finish technologies can be used. Industrial finishes offer qualitatively a far superior finish compared to any site-based system.
An industrial coating, forms a very small and often a negligible part of the total cost of the product, its failure in any form destroys the entire value of a product, and manufacturing company’s reputation. Defects of industrial coatings, if any are realized after the product has reached the consumer. Remedial measures are impracticable, and it entails a recall of the product from unknown or far off locations. Industrial coatings must be continuously upgraded. Otherwise, a technologically superior product gets rejected from the market due to its aesthetic and sensorial appeal.
Industrial finishes are generally low in pigments or extenders and high to medium ‘build’. Quality of the finish is largely determined by the type of film forming mediums used. Many industrial finishes are formulated for baking-drying to achieve a hard, stable and durable finish. Amino and epoxy resin coatings dry by catalyst action. In powder coatings thermo-setting materials are heat liquefied to set. Industrial coatings also include air drying, partially air drying & low temp baking, stowing, radiation-curing, solvent-evaporating, oxygen polymerizing (oxidizing) heat polymerizing and catalyst curing, thermo plasticizing carbonating, systems. Industrial products receive pre-treatments to make their surfaces suitable for a single system of coating and through single application. The pre-surface treatment include moisture conditioning, rust inhibiting, galvanic control, texturing and levelling of the surface, etc.
Industrial finishes can be classified as:
- Traditional systems
These are based on alkyd resin technology
High molecular weight resins, such as vinyls, acrylics, chlorinated rubber, etc. that are dissolved in a solvent and do not undergo any chemical change on drying.
- Dispersion mediums
These are dispersions of convertible system.
- Latex systems
Contain resins dispersed in water or other liquid that do not dissolve them. Resins are invariably high molecular weight polymers.
- Chemically curable systems
These are made of thermo-setting resins of low molecular weight such as epoxies or urethane, that in the presence of a chemical or catalyst complete the bond formation.
Today industrial coatings are also seen in terms of environmental compliance, or the pollution hazard they can cause. The total volatile organic component, VOC. criteria is a factor that defines the worthiness of a coating system.
Water borne coatings:
These are made from emulsion, water reducible and aqueous colloidal dispersions.
High solid coatings:
High solid coatings are frequently based on conventional polymers but with low molecular weight.
These are based on thermoset and thermoplastic resins with pigments, fillers and additives such as hardeners and flow agents.
Advantages of Industrial coatings: Items which are difficult to coat due to their shape, size or location can be efficiently coated in an industrial set up. Items with sharp corners and edges can be coated evenly. Certain types of pre-treatments, which are not possible on a building site can be carried out at plant level. Materials and methods which are difficult to handle, or are normally hazardous on a site, can be employed at plant level. Industrial application of coating is very efficient and controlled so very thin film thickness can be achieved, and lot of wastage on account of drips and over sprays can be eliminated. Many application techniques, tools, equipment can only be used at plant level set up.
Industrial Coatings include White goods (consumer products of chiefly white-coloured, but not always; such as refrigerates, washing machines, ovens, gas stoves, geysers, fans, air conditioners); Consumer electronic products such as computer and server cabinets; Industrially produced furniture such as chairs, cabinets, tables, partition systems; Vehicle products such as cycles, scooters, bikes, cars, trucks, buses; Extruded or formed Long products such as steel, aluminium and composite sections, and pipes; Besides these there are several applications where clear (pigment less) or non toxic coatings are used such food containers, toys, etc.