Optical Brightening Agents (OBA): The Science of Perfect Whiteness in Textiles
In the textile industry, the perception of "white" is the most important indicator of quality and cleanliness. However, raw fibers (cotton, wool, or synthetics) naturally have a yellowish tone. Where traditional bleaching methods fall short, Optical Brightening Agents (OBA) step in to maximize the degree of whiteness perceived by the human eye through physical and chemical methods.
Optical brighteners offered under the Sunbright brand in the sector have molecular structures customized according to the type of fiber they are applied to.
Working Principle: Making Invisible Light Visible
The mechanism of optical brighteners is much more complex than a simple dyeing process. These substances work according to the principle of "Fluorescence":
- UV Absorption: OBA molecules absorb Ultraviolet (UV) rays present in daylight but invisible to the human eye (300-400 nm range).
- Energy Conversion: These absorbed high-energy rays are processed within the molecular structure, and their wavelength is changed.
- Blue Light Emission: The OBA reflects the absorbed energy back in the blue-violet region of the visible spectrum (400-500 nm).
Result: When this reflected blue light combines with the natural yellow tone on the fabric, the human eye perceives the fabric as "neutral white" or "extra bright white." In this way, the fabric looks much cleaner and more vivid than it is.
Sunbright Product Family and Classification
Since the chemical structure of every fiber is different, the binding (affinity) mechanism of the optical brightener to the fiber must also be different. Sunbright offers solutions in three main categories to meet this need:
1. Sunbright (For Cellulosic Fibers)
Developed specifically for cellulose-based fibers such as cotton, viscose, linen, and rayon.
- Usage Area: Can be used in exhaust, pad, and continuous systems.
- Properties: Provides high affinity by establishing hydrogen bonds with cellulose fibers. Thanks to its resistance to peroxide baths, bleaching and brightening processes can be done in the same bath, which provides time and energy savings for businesses.
- Shade Options: Sub-variations are available based on whiteness tones.
2. Sunbright (For Polyester Fibers)
Used for whitening hydrophobic and dense synthetic fibers like polyester.
- Usage Area: Applied in High Temperature (HT) dyeing machines or via fixation (thermo-fixation) methods in stenters.
- Properties: High dispersion property. Since it possesses high sublimation fastness, the fabric maintains its whiteness and brightness even if exposed to subsequent thermal processes.
Critical Factors in Optical Brightener Selection
When selecting the right Sunbright product, the following criteria should be taken into consideration:
- Fiber Type: The correct Sunbright product must be selected for the fiber type. Incorrect selection leads to spot problems or insufficient whiteness.
- Application Method: Whether exhaust or padding is to be performed determines the solubility properties of the product to be selected.
- Desired Color Tone (Shade): Optical brighteners do not just make it "white"; they also determine the tone of the white. While some customers want a "reddish warm white," others request a "bluish cold white." Sunbright series allow for these tone adjustments.
Comparison Table: Sunbright OBA Series
| Product Group | Target Fiber | Binding Type | Key Feature |
| Sunbright | Cotton, Viscose (Cellulose) | Hydrogen Bonds | Peroxide resistance, economical process. |
| Sunbright | Polyester (Synthetic) | Solid Solution | High heat (sublimation) fastness. |
| Sunbright | Nylon, Wool (Polyamide) | Ionic Bonds | High efficiency in acidic environment. |