 |
|
Products >> TYPES OF LACQUERS, CURING OF LACQUER & PERFORMANCE TEST OF CURED LACQUER
 |
|
 |
|
|
(1) TYPES OF LACQUERS
Lacquer is organic coatings based on a resin substance, which is spread out as a relatively thin film. Resin is a hydrocarbon secretion of many plants, particularly coniferous trees, valued for its chemical constituents and is used in varnishes, adhesives and as an important source of raw materials for organic synthesis. The resin produced by most plants is a viscous liquid. Synthetic resins are materials with similar properties to natural resins—viscous liquids capable of hardening. They are typically manufactured by esterification or soaping of organic compounds.
Acrylic lacquer polymer emulsion. Lacquers using acrylic resin, a synthetic polymer, were developed in the 1950s. Acrylic resin is colourless, transparent thermoplastic, obtained by the polymerization of derivatives of acrylic acid. The advantage of acrylic lacquers is an exceptionally fast drying time. Acrylic lacquers can be diluted with water, but become water-resistant when dry.
Polyurethane is any polymer consisting of a chain of organic units joined by urethane links. Polyurethane can be made in a variety of densities and hardness by varying the type of monomer(s) used and adding other substances to modify their characteristics, notably density, or enhance their performance. Other additives can be used to improve the fire performance, stability in difficult chemical environments and other properties of the polyurethane products.
Epoxy or polyepoxide is a thermosetting epoxide polymer that cures (polymerizes and crosslinks) when mixed with a catalyzing agent or "hardener". Epoxy coatings are also widely used as primers to improve the adhesion of automotive and marine paints especially on metal surfaces where corrosion (rusting) resistance is important. Metal cans and containers are often coated with epoxy to prevent rusting especially for foods like tomatoes that are acidic.
-------------------------------------------
(2) CURING OF LACQUER
Lacquer is cured using following methods
(a) Oven
(b) Infra red heat
( c) UV cure – (Not suitable for electrophoretic lacquers)
-------------------------------------------
(3) PERFORMANCE TEST OF CURED LACQUER
Lacquer performance is measured with following test.
(a) Film thickness: from 3 to 24 microns
(b) Pencil hardness: from 2H-6H
(c) UV resistance: Poor or excellent
(d) Acetone resistance: from 300 to 2,000 rubs
(e) Dry and Wet Adhesion: 100%
(f) Salt spray test: 240 to 480 hours on chromated brass
-------------------------------------------
|
|
|
|
|
|
|
|
|
 |
