|Melting Point (oC)||359-361|
|Appearance||Greenish Crystal Powder|
|Volatile Content, Max%||0.5% Max|
|Particle Size||200 meshes|
Optical brighteners function by absorbing ultraviolet radiation and re-emitting blue light. The emitted blue light will reduce the yellow color of a polymer. In the presence of a whitening agent, such as Tio2, the use of OB-1 will produce a brilliant white or "whiter than white" appearance.
Two primary factors affect the whiteness/yellowness of formulation. They are the color of the base polymer and the level of brightener added. If no whitening agent such as Tio2 is used, the level of OB-1 required will likely be lower than when a whitening agent is present. This level might be as little as 25-50ppm.
In determining the optimum concentration of brightener, the effect of any other UV-absorbing materials in the plastic should be considered. It is important that users perform sufficient evaluations to determine the optimum level of OB-1 for their specific end users.
To be effective, an optical brightener must dissolve in the polymer to which it is added. Since the typical addition levels for OB-1 is in the range of 100-400 ppm, the use of a concentrate, or master batch, is recommended. Concentrates containing 1%-10% by weight of OB-1 are typical.
The concentrate can be produced on an extruder using normal processing conditions for the polymer, including drying if necessary. The concentrate is then let down to typical use levels in the final formulation. Plastics compounding equipment is normally adequate for producing OB-1 brightener formulations.
The key requirement is to thoroughly disperse the brightener so that it will dissolve uniformly throughout the molten polymer. This is usually achieved most readily with a concentrate.
The business of processing post consumer plastics and waste polymers continue to grow. These materials can be recycled into a variety of useful products, from plastic lumber to synthetic fiber.
Polyester bottle polymer, Polyester plastic waste, and waste fiber polymer can be recycled into polyester fiber that can be used in carpets, filling and insulation material, non-woven's, and apparel. One of the shortcomings of processing these materials is the uncertainty of the color of the source material.
By using optical brighteners, the value of the recycled materials can be significantly enhanced by providing a more uniform white. OB-1 will greatly improve the whiteness. Normal fiber applications require only 200-300 ppm in new polymer, but recycled material may require as much as 300-450 ppm.
Optical brighteners are very effective in improving the appearance of the polymer or fiber. Off-class or second-quality nylon polymer can also be improved in the same way.
OB – 1 complies with regulations for indirect food additives OB – 1 is restricted to use as an optical brightener for all polymers at a level not to exceed 0.025% by weight of polymer and at a temperature not exceeding 135oC (275oF)