FAQsFluorescent Whitening Agent OB-1
Time：2025-09-19Views：
During the use of Fluorescent Whitening Agent OB-1, you may encounter problems such as unideal whiteness/brightness of the product, or even yellowing. Below are detailed explanations.
Why is the product still not white enough after adding OB-1?
- Inappropriate model selection: There are various types of fluorescent whitening agents for plastics on the market. Although OB-1 has wide applicability, if your product is made of special materials and the mismatched model is chosen, it will be difficult to achieve optimal results. For example, some special plastic blending systems may require compounding OB-1 or selecting more targeted whitening agents. Meanwhile, ensure the quality of OB-1: the content of whitening agents on the market varies greatly, and shoddy products (passing low-quality ones as high-quality) are common—such products will naturally fail to reach the expected whiteness.
- Unreasonable addition amount: More OB-1 is not better. It has a "yellowing point": if the amount exceeds this threshold, there will be no whitening effect; instead, the product will turn yellow. If the amount is too low, OB-1 cannot function fully. Generally, the dosage of OB-1 is 0.0025%-0.005% for transparent plastics and 0.01%-0.03% for opaque plastics. The specific dosage must be determined through tests based on the actual product conditions.
- Interference from other additives: If ultraviolet (UV) absorbers are used during production, they may affect OB-1’s whitening effect. The working principle of OB-1 is to absorb UV light and convert it into blue-violet light, which offsets the yellow light of the product to achieve whitening. UV absorbers will reduce OB-1’s absorption of UV light. In addition, components like titanium dioxide in white pigments can also absorb UV light, weakening OB-1’s whitening effect.
Why is the product’s brightness not up to expectation after adding OB-1?
- Uneven dispersion: Uneven dispersion of OB-1 in the product leads to inconsistent local whitening effects, affecting the overall brightness. This often occurs if proper dispersion equipment and processes are not used during processing. For example, in plastic processing, dispersion can be improved by adding dispersants or increasing stirring speed.
- Product base color issue: If the product itself has a dark base color or contains excessive pigments, OB-1 alone cannot significantly improve brightness. OB-1 mainly achieves optical brightening. For products with dark base colors, it is recommended to first perform pretreatment (e.g., chemical bleaching) before adding OB-1 to achieve the desired brightness improvement.
Why does the product turn yellow after using OB-1?
- Excessive addition: If the amount exceeds the optimal dosage, the excess OB-1 cannot fully integrate with the product. It may precipitate on the surface and show its inherent yellow color, causing yellowing.
- Over-high processing temperature: The melting point of OB-1 is above 359℃. However, if the processing temperature is close to or exceeds this melting point for a long time, OB-1 will decompose (lose efficacy) or even carbonize, making the product yellow and dull. For plastic products processed at high temperatures, strictly control the processing temperature.
- Insufficient weather resistance: OB-1 has relatively poor weather resistance. If the product is used in harsh environments (long-term exposure to sunlight, rain, wind, etc.), OB-1 will gradually lose efficacy, leading to yellowing. For outdoor products, it is advisable to add additives (e.g., antioxidants, light stabilizers) to improve OB-1’s stability, or compound OB-1 with a whitening system that has better weather resistance.
