Powder paints are a modern and environment friendly solution of surface treatment for many products.
Basic characteristics of powder paints
Powder paints belong to the group of so called industrial coating compositions. They consist of a mixture of resins, pigments, and possibly other raw materials providing powder paints e.g. with hardness, gloss or required depth of matt, they create structural surface, etc. The mixture is of dry powder consistence. For application purposes, the powder paint is not thinner with anything, it is diluted in any liquid. It is applied in the form of powder by pressed air which makes a liquid mixture after mixing with powder paint.
Production of powder paints
In contrast with liquid coating compositions, where individual components are mixed during the production and they interact with each other in a water or thinner solution, the individual components of powder paints are mixed in a melt. Then, the melt is pushed by the production device o the cooling rolls and after it cools down, it is milled in special mills to required crudeness of powder material particles. The resulting mass is the final production product – the powder paint.
Range of powder paints application
At the present time, you can meet product with powder paint coat practically everywhere. Powder paint application is used on products of so called white program (washers, refrigerators, kitchen stoves, microwave ovens), metal furniture and household accessories, safes, locks, hangers, consumer electronics covers, bicycles, sport and fitness equipment, office and study accessories, magnetic boards, small items that we can standardly meet (shorehorns, openers), parts for automotive industry (brake-pad plates, wheel discs, metal parts of interior, many components for motorcycles), radiators, extinguishers, letter boxes, lighting elements and fittings, bottles for perfumes and some types of alcohol drinks, decorative pots, cigarette and tobacco cases, electric distribution boxes, armatures and many others.
Classification based on carriers, their characteristics
Thermo sets are wide spread and generally used powder paints.
Depending on carriers, we divide them into the following basic types:
Designed for interiors
- Epoxy (EP) – designed exclusively for interior use. They are very well resistant to corrosion and some chemical substances.
- Epoxy - polyester (PEP), so called hybrids or generally called „mixes“, they are currently most frequently used powder paints. They are designed mainly for interior use, but they can also be used for products facing weather influences on short.-term basis.
Designed for exteriors
- Polyester powder paints (PES) – they are designed mainly for exterior use due to their high resistance to UV radiation and other weather effects.
- Polyurethane powder paints (PUR) – they are highly resistant to weather influences. Transparent polyurethane powder paints show high clarity.
- Acrylate powder paints (AC) can be used even in exteriors, their strong points include i.a. high resistance to chemical substances.
Colour scheme, type scheme
The most wide used in the market are the epoxy, hybrid and polyester powder paints. These powder paints are generally produced in many appearance types and a really wide scale of tints. The scale of tints is usually based on internationally recognised colour chart RAL . Powder paints are manufactured in high gloss up to deep matt types. Depending on their surface, powder paints can be classified as smooth-surface types, fine structural surface types and rough structural surface types.
Along with these basic types there are also manufactured powder paints with various appearance effects (for example so called metallic paints, antiques, shells, glitters, etc.).
Application of Powder Paints
Powder paints are applied to suitably pre-treated base, free of any chemical and mechanical impurities.
The powder paint is mixed with pressure air in an application device and it is driven from the tank through a hose to the application pistol and sprayed on the product. So as the applied powder sticks on the surface, the application device provides it with electrostatic power causing attraction of its particles to sprayed product and consequent sticking to it. It is said that the powder is „charged“ in the application device. The „charging“ is arranged in two basic ways: friction with the inner walls of the special application pistol, made of teflon (so called tribo) or by obtaining the charge using the high voltage electrode placed in the outlet of the application pistol so called corona or statics).
Consequent hardening in toughening furnace finishes the whole application process. After hardening, the product is taken out of the furnace and after cooling down, it is immediately ready for assemblage, completion, or possibly even for packing and forwarding.
The powder paints are a single-layer paining system that does not require application of primary coats and no drying is needed after application. This characteristics allows reaching quite high work productivity as well as economic savings in case of optimal managing of the application technology.
Environment and Waste
The great advantages of surface treatment with powder paints include environment friendly conditions of operation and ecological parameters of final coat characteristics compared to surface treatment with application of most of common liquid paints. The powder technologies do not use solvents, the substance is applied in powder form and in case of technologies with the possibility of powder re-circulation is the application waste really minimal. More, the residual powder paint (waste from spraying) can be regenerated under specific conditions and then re-used.