What is Optical Brightener OB-1?

Optical Brightener OB-1 (CAS No. 1533-45-5) is a highly efficient fluorescent brightener belonging to the benzoxazole class. It absorbs ultraviolet light (UV) and emits blue-violet fluorescence, effectively neutralizing yellow tones and making materials appear brighter and whiter.

Physical and Chemical Properties of Optical Brightener OB-1

How Does Optical Brightener OB-1 Work?

1. UV Absorption & Fluorescence Emission: OB-1 absorbs UV light (300-400nm) and converts it into blue-violet visible light (420-460nm).

2. Shade Correction: The emitted blue-violet light counteracts yellowing, making products look whiter and more vibrant.

3. Enhanced Light Reflection: It increases brightness, giving materials a cleaner, glossier appearance under natural or LED lighting.

Key Features of Optical Brightener OB-1

High Heat Resistance (Withstands >350°C), suitable for high-temperature plastic processing (extrusion, injection molding, blow molding, etc.).
Excellent Light & Weather Resistance, long-term UV exposure does not cause yellowing.
High Whitening Strength, effective in small dosages, cost-efficient.
Great Compatibility, applicable to various polymers (PVC, PP, PE, PS, ABS, PET, etc.).
Non-Migrating, ideal for fibers, plastics, and coatings that require long-lasting whiteness.

Main Application Industries of OB-1

Plastics Industry: Used in PVC, PP, PE, PS, ABS, PET, PC, EVA, and other plastic products (pipes, sheets, films, injection-molded parts, light diffusion sheets, etc.).
Synthetic Fiber Industry: Whitening of polyester (PET), nylon (PA), and acrylic (ACR) fibers.
Coatings & Inks: High-performance coatings, industrial inks, powder coatings.
Rubber Products: Improves brightness in rubber soles, rubber sheets, etc..

Why Are PVC Products Not White Even When Using New Materials?

During the production of PVC products, even when high-quality new materials are used, the final products may still lack the desired brightness and whiteness. This issue is often caused by raw materials, formulation, processing conditions, environmental factors, or equipment issues.

1. Raw Material Issues

Color of PVC Resin: Even with virgin PVC materials, some resins may have a slight yellowish tint, reducing the final whiteness of PVC products.

Impact of Fillers and Additives: Fillers like calcium carbonate (CaCO₃) can contain impurities or discoloration, affecting product appearance. Choosing high-purity fillers is essential.

2. Formulation Issues

Insufficient Optical Brighteners: The lack of Optical Brightener OB-1, fluorescent brighteners, or PVC whitening agents may lead to dull or yellowish PVC products. Optical brighteners like OB-1 for plastics effectively neutralize yellowing and enhance PVC whiteness.

Improper Formulation Ratio: Stabilizers, lubricants, and UV absorbers in PVC formulations may impact the optical brightening effect. Using the right amount of OB-1 or other plastic brightening agents can significantly improve results.

3. Processing Issues

Excessive Temperature: Overheating during PVC extrusion or injection molding can cause the decomposition of PVC optical brighteners like OB-1, affecting whiteness.

Uneven Mixing: Poor dispersion of PVC brightening additives results in uneven whitening effects. Using high-dispersion fluorescent whitening agents ensures uniform color enhancement.

Extrusion and Molding Problems: Improper machine settings (e.g., extrusion speed, pressure, and cooling rate) can impact PVC product brightness.

4. Environmental Factors

Lighting Conditions: The performance of fluorescent whitening agents for PVC depends on UV exposure. Poor lighting in the manufacturing environment can reduce optical brightener efficiency.

Storage Conditions: Prolonged exposure to heat, light, or humidity can degrade plastic optical brighteners, reducing their effectiveness in PVC whitening.

5. Equipment Issues

Equipment Contamination: Residual old materials or degraded optical brighteners in machinery can cause color inconsistencies.

Aging Equipment: Outdated PVC processing equipment may lead to temperature fluctuations, affecting brightener activation.

Solutions to Enhance PVC Whiteness

Check Raw Materials: Choose high-whiteness PVC resin and ensure that CaCO₃ fillers are free from impurities.
Optimize Formulation: Increase Optical Brightener OB-1, PVC whitening agents, and fluorescent brighteners to achieve optimal whitening effects.
Control Processing Temperature: Maintain PVC extrusion and molding temperatures within the recommended range to preserve the effectiveness of optical brighteners.
Improve Mixing Uniformity: Ensure even dispersion of OB-1 and color enhancers for a consistent whitening effect.
Inspect Equipment Regularly: Clean and maintain PVC manufacturing equipment to avoid brightener contamination issues.

Summary

Even when using high-quality new materials, PVC products may still appear yellowish or dull due to raw materials, formulation errors, processing conditions, and equipment problems. By integrating Optical Brightener OB-1, fluorescent whitening agents for plastics, and PVC brightening solutions, manufacturers can significantly enhance whiteness, improve product quality, and gain a competitive edge in the market.

In PVC formulations, both ultramarine blue and optical brightener OB-1 are used to improve the whiteness and appearance of products, but their mechanisms and effects differ. Below is a detailed comparison:

1.What is the role of ultramarine blue in PVC formulations?

• Function:

• Color Adjustment: Ultramarine blue is a pigment primarily used to neutralize yellow tones in PVC, making white appear cooler and brighter.

• Covering Power: It enhances the covering power of PVC, reducing the impact of the base color on the final appearance.

• Characteristics:

• Does not emit light; it adjusts color by absorbing yellow light.

• Provides stable results but has limited whitening effects.

2.What is the role of Optical Brightener OB-1 in PVC formulations?

• Function:

• Whitening: OB-1 absorbs ultraviolet light and emits blue light, neutralizing yellow tones and significantly improving the whiteness and brightness of PVC.

• Brightening: It makes PVC appear brighter and more vibrant.

• Characteristics:

• Has a fluorescent effect, providing significant whitening.

• Sensitive to light conditions, suitable for applications requiring high whiteness and brightness.

3. Comparison of Whitening Effects between Ultramarine Blue and Optical Brightener OB-1 ?

4. How to choose Ultramarine Blue or Optical Brightener OB-1 in PVC formulations?

• If significant whitening and brightening are needed: Choose optical brightener OB-1, especially for PVC products used under light conditions (e.g., outdoor building materials, packaging).

• If color adjustment and improved whiteness are needed: Choose ultramarine blue, suitable for general white PVC products or used in combination with OB-1 for optimal results.

Summary

• Optical brightener OB-1 provides better whitening effects and is suitable for PVC products requiring high whiteness and brightness.

• Ultramarine blue is mainly used for color adjustment and is suitable for general white PVC products or combined with OB-1.

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