Properties: The films of Urethane varnishes exhibit the following properties which are superior to those conventional media.
1) Almost colorless, hence suitable for all shades and colors including pure whites.
2) Very rapid rate of initial drying even at low ambient temperature.
3) Thorough drying & Very tough film.
4) No special solvent required conventional solvent e.g. Mineral Spirits is adequate.
5) Excellent abrasion resistance and scratch hardness.
6) Excellent resistance to chemicals and water.
7) Presence of free NCO is negligible and is completely non- hazardous and absolutely safe for handling even by unskilled workers.
8) Can withstand temperature from +160 to -25°C.
9) Dust repellent and antifungal.
10) Excellent salt spray resistance.
11) Can be processed in the manner similar to those for Alkyds with which all Paint manufacturers are familiar.
12) Ability to cure fast at very low oven temperatures such as 5-10 mts at 140-150°C, leading to higher rate of production with low energy consumption.
COMPATIBILITY: Silac U220 is compatible with all Drying oils, Long and Medium oil Alkyds, Epoxies, Estergums, Phenolics and Maleics in all proportions and only to a limited extent in Chlorinated resins, Short oil Alkyds and Urea resins.
SOLUBILITY: Silac U220 is soluble in Mineral Turpentine Oil (M.T.O) in all proportions. They are also soluble in most of the common paint solvents like Xylene, Naphtha’s, Esters and Ketones. Wherever the ‘U' Resins have to be used with other resins of limited solubility in MTO like Epoxies & Vinyls etc, other suitable solvents like Toluene, Xylene or Ethyl methyl ketone should be used.
RECOMMENDED DRIERS: Since 'U' Resins are very rapid drying comparatively smaller quantity of Cobalt drier that is 0.3% to 0.5% of Cobalt as metal on the solid resin content will be adequate. However, if faster drying is required driers upto 0.4% Zirconium and 0.5 % Cobalt as metals on the resin contents can be further added, After addition of driers ageing for 24 hours in air tight containers is recommended. The oil modified urethane coatings dry (or cure) by the usual oxidation process as applicable to drying Alkyds and unsaturated oils hence require conventional driers. While the other types of Urethanes such as Moisture cured, Blocked type or the Two pack systems cure by the reaction of Isocyanate groups with Hydrogen thus require special type of drier chemicals.
MODE OF SUPPLY: Presently the 'U' Resin is supplied in 200 or 25 kg’s packing’s as 60% & 70% solids. Solid contents can be customized as per the requirements of customer. We can also supply the above ‘U’ Resins up to 70% solids only and packed in MS Drums with 200 Kg’s net packing.
COMPARATIVE FILM PROPERTIES: 'U' Resins represent the latest high technology development in the surface coatings field, they have made possible to manufacture superior grade enamels which are very popular abroad both for decorative and Industrial applications. Their performance is usually compared with Alkyds which are widely used by the Paint Industry. The following table presents the comparative advantages and disadvantages of 'U' Resins with alkyd resin varnishes, Cardanol based Styrenated Phenolic resin (i.e. Silex 55) is also included as a reference point being our very popular resin. The comparison is made between the films of varnishes of the above with 30% solids and MTO as solvent.
SUPERIORITY OF OIL MODIFIED POLYURETHANES OVER OTHER P.U. SYSTEMS: It can be seen from the following table that all other P.U. Systems require special costly thinners. Special techniques for pigmentation, costly driers and specially trained labour for handling paints based on them as they contain free N.C.O. They also have limited pot life. The only advantage which they have over modified PU Systems is better hardness of the film and better chemical resistance in some cases.
APPLICATIONS: The unique and excellent film forming properties of 'U' Resins have made possible their use in a very wide range of applications. Some of the areas where they have shown considerable promise are:
Water Proofing of Cement structures
Floor varnishes & Maintenance Coats
Leather, Rubber and FRP Industry
Chemical Process Industry
Marine Industry Under Water paints and bathroom Room wall paints
Primers and undercoats
Medium for aluminum paints