Technical Bulletin: Performance Comparison of Plastic Fluorescent Whitening Agents
Brought to you by Tonex Chemical – Your Trusted Partner in Optical Brightener Solutions
1. Light Fastness (Ranking)
The lightfastness performance of commonly used fluorescent whitening agents (FWAs) is ranked as follows:
Optical Brightener KCB = OB ＞ KSN ＞ OB-1 ＞ ER-2 ＞ ER-1 = FP-127
This ranking indicates that KCB and OB offer superior resistance to UV-induced degradation, making them ideal for outdoor or long-term exposure applications.
2. Heat Resistance
Optical Brightener OB-1 and Optical Brightener OB demonstrate the most outstanding thermal stability among all FWAs.
Pure OB-1 powder can withstand processing temperatures up to 370°C, making it the top choice for high-temperature engineering plastics.
Important Note: If the OB-1 contains fillers or auxiliary additives, its heat resistance will be significantly compromised. Tonex Chemical strictly controls product purity to ensure consistent, reliable thermal performance across all batches.
3. Whitening Effectiveness (in PVC)
When evaluated in PVC systems, the whitening efficiency ranking is:
FP-127 ＞ KSN ＞ OB-1 ＞ ER-2 ＞ KCB ＞ ER-1 = OB
For maximum optical brightness in PVC applications, FP-127 and KSN are the preferred choices, while OB-1 offers a balanced combination of whiteness and heat resistance.
4. Recommended Dosage Guidelines
|
Application Type |
Recommended Dosage (per 100 kg material) |
|
Transparent products |
0.1 g – 5 g |
|
Opaque products |
10 g – 50 g |
|
Recycled or filler-containing materials |
50 g or more (depending on base color) |
Tonex Chemical provides customized dosage recommendations based on your specific resin system and processing conditions.
Key Usage Precautions
1. Migration (Bloom/Frosting) Risk
When using OB-1 in PE and flexible PVC, strict dosage control is critical. Excessive addition can lead to surface migration (blooming).
A safe starting point is approximately 0.02% of total formulation weight.
If migration occurs, also verify whether dye loading is excessive, as dyes can migrate in PE, PP, flexible PVC, and PA systems.
Tonex Chemical Tip: Our technical team can help you determine the optimal dosage to maximize whiteness while minimizing migration risks.
2. Uniform Dispersion is Essential
Because FWA dosages are extremely small, high-speed and thorough mixing is mandatory. Poor dispersion will result in uneven coloration – typically appearing as mottled, streaky, or spotted surfaces.
Tonex Chemical recommends using a two-stage mixing process (pre-blending with a carrier resin or masterbatch approach) to achieve uniform distribution.
3. Compatibility with UV Absorbers
Adding UV absorbers to the polymer system improves overall weatherability but does not significantly enhance or preserve the whitening effect of FWAs.
When UV absorbers are used, it is advisable to moderately increase the FWA dosage to compensate for reduced whitening efficiency.
Tonex Chemical offers complementary additive packages that balance UV protection and optical performance for your specific formulation.
4. Special Considerations for Recycled Materials
Yellowing in recycled plastics is most often caused by thermal degradation due to excessively high processing temperatures.
Adding whitening agents or blue/violet dyes under these conditions may unexpectedly cause yellowing or greening of the final product.
Critical Advice: Do not simply keep increasing the FWA dosage to correct this issue. Instead:
Improve the quality of the recycled feedstock, or
Lower the processing temperature to minimize thermal stress.
As Tonex Chemical always emphasizes: The right formulation starts with stable base materials. No amount of whitening agent can compensate for poor-quality recycled feedstock or improper processing conditions.
Why Choose Tonex Chemical?
Superior Product Purity – Our OB-1 and OB series deliver guaranteed heat resistance up to 370°C.
Comprehensive Technical Support – From dosage optimization to migration prevention, we work alongside your R&D team.
Consistent Quality – Strict quality control ensures batch-to-batch reliability.
Application Expertise – With years of experience across PVC, PE, PP, PA, and engineering plastics, we understand your challenges.
Contact Tonex Chemical today to find the right fluorescent whitening agent solution for your plastic applications.