Benzoin is a yellowish or white crystalline compound prepared by condensation of benzaldehyde in potassium cyanide or sodium cyanide ethanol solution. Benzoin is a chiral molecule, which has a pair of mirror image isomers of (R)-benzoin and (S)-benzoin.
The biggest industrial use of benzoin is to be used as a defoamer for polyester powder coatings. Benzoin can sublimate at 100 degrees C, thus continuously exhausts gas during the drying process of powder coatings to prevent needle holes on the coating surface. Generally, the dosing in powder coatings is about 0.3%.
The main uses of benzoin are as a precursor to benzil, which is a photoinitiator. The conversion proceeds by organic oxidation using copper(II), nitric acid, or oxone. In one study, this reaction is carried out with atmospheric oxygen and basic alumina in dichloromethane.
Appearance: white or light yellow crystal
Melting range: 132～137℃
Solid content: ≥99.0%
Application and Performance
- Benzoin can eliminate bubbles in the powder coating.
- It is suitable for various types of powder coatings.
- Dosage: 0.3-0.8% of the total powder amountand the specific dosing needs to be determined via experiment.
- Use Method: Benzoin can be directly added to the raw materials, mixed and extruded with other materials.
- The dosage of benzoin in powder coatings should be controlled because it will affect the yellowing of the coating film.
Packaging, storage and precautions
Packing in multi-layer craft paper bag packaging with polyethylene lining, net weight 25 kg.
Store in a cool and dry place, away from fire and heat.