Optical brightener OB

  • Product Name: Optical Brightener OB
  • Chemical Name: 2,5′-Bis[2-(5-tert-butyl-2 benzoxazole)thiophene
  • C.I.:  184
  • CAS: 7128-64-5
  • Molucular Formula: C26H26N2O2S
  • Formula Weight: 430
  • Synonyms: Tinopal OB (OB-C, OB-P), Uvitex OB, Whitex NSK.
    OB 184, FBA 184, Optical Brightening Agent OB
  • Application: widely used in whitening of PVC, PS, ABS, PP, PE, oil-based paints and coatings.
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1. Properties of Optical Brightener OB

Appearance: Light yellow powder
Purity: 99.80%
Melting point: 201.1-202.2℃
Volatile 0.24%
Ash 0.03%
Max Absorption Wavelength 375nm (in ethanol)
Max. Emission Wavelength 435nm(in ethanol)

Optical brightener OB chemical structure

Optical brightener OB chemical structure

Optical brightener OB is poorly soluble in water, and soluble in alkane, mineral oil, and common organic solvents.

Solubility in comment Solvent. (g/100 mL, 25℃)

Acetone 0.2                   Cyclohexanone 3             Ethylene Glycol 0.2
Tetrahydrofuran 5       Butanol 0.2                      Dimethylformamide 0.8
n-Hexane 0.2               Toluene 5                          Carbon tetrachloride 5
Dioctyl phthalate 0.7  Methanol 0.05                 Turpentine 0.1
Chlorobenzene 10        Dioxane 2                         Methyl ethyl ketone (MEK) 1
Xylene 5                         Chloroform 14                 Ethyl acetate 1
Methylene chloride/methanol (9:1) 2                 Water <0.01

2. Synonyms / Alternative

Tinopal OB (OB-C, OB-P), Uvitex OB, Whitex NSK.
OB 184, FBA 184

3. Packing and Storage

25KG fiber drum lined with a double-layer plastic bag.
Stored in a cool, dry, and ventilated place, the storage term should not exceed 2 years.

4. Common Application and Recommend Dosage

Optical brightener OB is widely used in  PVC, polystyrene, polyethylene, polypropylene, thermoplastic plastic, ABS, and cellulose acetate fiber. And oil-based paints, coatings, inks, etc. It has excellent heat resistance and light stability.
PVC       White:  0.01-0.05%     Transparent:  0.0001-0.001%
PS          White:  0.01-0.05%     Transparent: 0.0001-0.001%
ABS       Natural: 0.01-0.05%    Transparent: 0.0001-0.001%
PE, PP   White: 0.005-0.05%     Transparent: 0.0005%-0.005%
Oil-based Paint/coatings/inks:   white: 0.01-0.02% (10-20g/100kgs resins)  Transparent:  0.0001-0.001%.

Optical brightener OB work with color dyes can enhance color brightness, especially in color formulations.
When using any UV absorb additive, the dosage of OB should be adjusted.

5. Transportation and Safty

Avoid inversion, sunlight, moisture, and crash. Avoid damaging the package.
Non Hazardous. Stock as ordinary chemicals. Wear Protective goggles and gloves while using. And avoid direct contact with skin and eyes. Soap clean if the skin is contaminated.


Shandong Grand Chemical Co., Ltd, is a professional manufacturer of optical brighteners in China.
If you have any inquiries about optical brighteners for plastics, please do not hesitate to contact us via sales@obachemical.com, or WhatsApp: +86 13173009832.

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