Description
Optical brightener (also called optical brightening agent, OBA, fluorescent whitening agent, FWA) is a chemical used to make materials—especially laundry, paper, and textiles—look whiter and brighter.
They do not remove stains or whiten chemically.
Instead, they change the way light is reflected from a surface.
Chemical Properties
| Property | Description / Typical Values |
|---|---|
| Common Chemical Families | Stilbene derivatives (e.g., distyrylbiphenyl), coumarins, benzoxazolyl derivatives, pyrazolines, triazines |
| General Molecular Formula | Varies; often large conjugated aromatic structures containing N, O, S atoms |
| Appearance | White to slightly yellow crystalline powder |
| Solubility | Water-soluble types: moderate to high; solvent-soluble types: soluble in organic solvents (e.g., alcohols) |
| pH Stability Range | Typically stable between pH 4–10 (laundry detergents around pH 8–10) |
| Melting Point | Usually > 200°C, often 250–350°C depending on structure |
| Fluorescence Peak Emission | 420–470 nm (blue region) |
| UV Absorption Maximum (λmax) | Typically 330–380 nm (UV-A region) |
| Charge Type (Ionic Nature) | Anionic (most laundry brighteners), nonionic, or cationic (for acrylic fibers) |
| Lightfastness | Moderate; tends to degrade under prolonged UV exposure |
| Compatibility | Stable with surfactants, builders, and bleaching systems (except strong oxidizers like chlorine) |
| Thermal Stability | High; suitable for textile processing and plastic incorporation |
| Biodegradability | Many stilbene-derived brighteners are poorly biodegradable |
| Toxicity | Generally low, but can cause environmental persistence |
Optical Brightener Grades for Detergents
These are water-soluble brighteners, mainly used in laundry detergents and cleaning products.
| Grade / Name | Chemical Class | Key Features | Applications |
| CBS-X (OB-27) | Stilbene derivative | High whitening power, highly stable in detergents | Laundry detergents, liquid & powder |
| CXT | Distyrylbiphenyl | Good solubility, strong blue tone | Detergent powders |
| DMA-X | Stilbene | Excellent fluorescence, stable in high pH | Premium detergents |
| BBS / DMS | Stilbene | Good performance in liquid detergents | Liquid detergents |
- Optical Brightener Grades for Textiles
Mostly for polyester, cotton, nylon, and blends. They differ in affinity and heat stability.
| Grade / Name | Fiber Compatibility | Properties |
| OB-1 | Polyester, plastics | High temperature stability (up to 300°C) |
| OB-3 | Polyester | Good brilliance and fastness |
| OB-2 | Cotton, wool, silk | Water-soluble, strong whitening effect |
| KCB (OB-84) | Polyester, polyamide | Bright blue-white shade, good lightfastness |
| KSB | Nylon, polypropylene | Good affinity and brightness |
- Optical Brighteners for Plastics & Polymers
These grades are heat-stable, making them suitable for extrusion, injection molding, and films.
| Grade / Name | Polymers | Key Features |
| OB-1 | PET, PP, PE, PVC | Excellent heat resistance, bright blue tone |
| OB-184 | Engineering plastics | High temperature (up to 350°C) clarity |
| OB-199 | PVC, PS, ABS | Strong fluorescence, low volatility |
| OB-KCB (OB-84) | PVC, PP | Compatible with many resins |
- Optical Brighteners for Paper
These are water-soluble FWAs optimized for paper bleaching, printing, and packaging.
| Grade / Name | Type | Use |
| FWA-5 (DAS) | Stilbene sulfonic acid derivative | Paper coating, surface treatment |
| FWA-4 | Distyrylbiphenyl | High brightness in fine papers |
| FWA-2 | Stilbene | Office paper, packaging |
| FWA-1 | Triazine-stilbene | Economical grade for bulk paper |
- Optical Brighteners for Cosmetics
Special low-toxicity grades:
| Grade / Name | Use |
| FWA-Cosmetic Grade | BB creams, under-eye brightening |
| Titanium dioxide + brightener blends | Skin tone correction |
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