Dehydration of castor oil is carried out at about 250 degree Celsius in the presence of catalysts (e.g., concentrated sulphuric acid, activated earth) and under an inert atmosphere or vacuum. Under this condition of dehydration, the hydroxyl group and adjacent hydrogen atom from the C-11 or C-13 position of the ricinoleic acid portion of the molecule is removed as water
Dehydrated castor oil is now recognized as an individual drying oil with its own characteristic properties and advantages. The drying oils owe their value as raw materials for decorative and protective coatings to their ability to polymerize or “dry” after they have been applied to a surface to form tough, adherent, impervious, and abrasion resistance films. The advantages claimed in surface coating applications include excellent odor and heat bleachability, good drying properties, more uniform polymer structure, and lack of after-yellowing.
DCO can be used to improve the quality of house paints, enamels, caulks, sealants and inks. It is used as primary binder for house paints, enamels, caulk sealant, and making varnishes.
This oil also works well in clear varnishes and hard finish coatings.
|Colour Gardner||6 Max|
|Acid Value||5 Max|
|Iodine Value||123 Min|
|Hydroxyl Value||25 Max|
|Saponification Value||185 – 194|
|Viscocity at 30 ºC||1.6 to 2.5 (poise 61 sec B4 cup)|
|Viscocity Gardner||G – J|