Castor oil is a triglyceride of fatty acids. Castor oil is found in castor beans In the seeds, its content is 35% to 57.%. “Castor oil is obtained by squeezing or solvent extraction. It is almost colorless or slightly yellow, clear and viscous liquid; has a slight odor; has a light taste and then is slightly pungent, and is easily soluble in ethanol. , can be mixed with absolute ethanol, chloroform, ether or glacial acetic acid, and should be widely used in coatings.
Castor oil can directly participate in the reaction to prepare polyurethane coatings:
When producing polyurethane coatings, polyisocyanate and polyester polyol are generally added. The relative molecular weight of the polyester polyol is generally required to be between 1000 and 3000, and the hydroxyl value is in the range of 160 to 300mgKOH/g. Castor oil is basically If it meets the above conditions, it can undergo polymerization reaction with isocyanate to produce polyurethane coating.
Castor oil-based polyurethane coating is a new polymer material that has emerged in China in recent years. Characteristics of castor oil-based polyurethane coating It has a high solid content and the long-chain non-polar fatty acids in the castor oil component make the coating film have good hydrolysis resistance and flexibility. The synthesis of this coating can be made by reacting castor oil with polyisocyanate to make a prepolymer. It is then made into a one-component or two-component coating.
A two-component polyurethane waterproof coating, which reacts with glyceryl ricinoleate and isocyanate to produce castor oil-type polyurethane, which is the main component of the waterproof coating. agent (called component A), plus coal tar, plasticizer, filler and curing agent (called component B) to form a two-component reaction-curing polymer coating waterproof coating. It has high tensile strength, It has high elasticity and elongation at break, good durability and temperature adaptability, excellent waterproof effect, and long service life. This type of waterproof material is widely used in developing countries such as Japan and the United States.
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