History of Optical Brightener
In 1929 someone found that aesculetin can emit fluoresces under ultraviolet light with the fabric, after being immersed in an aqueous solution, obtaining the whitening effect. The first commercially available optical brightener was produced by the Federal Republic of Germany Bayer organization in 1940. Since then, people have further developed a number of optical brightener agents.
What is Optical brightener?
The optical brightener (that is also known as the fluorescent brightener) is a transparent organic compound that can stimulate fluorescence under ultraviolet light. Many products we use every day include optical brighteners. Optical brightening agents are chemicals that manufacturers add to products like paper, plastics, and textiles to make them seem whiter and brighter and to reduce the natural yellowing process that happens over time. You can call this “White Enhancement Effect”. They additionally add these chemicals to cleaning agents to improve the look of materials after cleaning.
Its brightening impact is through the principle of the optically subsidiary color, making yellowing matters, after subjecting to fluorescent brightener treatment, not only can reflect visible light but additionally consume UV light outside the visible light into visible light of blue, yellow or cyan to be displayed. It is organic matters that can increase the whiteness of the fabrics and paper. Brighteners can absorb the ultraviolet in 330 to 360 nm wavelength with the reflected light being at a blue and violet light of the wavelength of 400 to 440 nm, coinciding with the yellow light returned from the fabric undergoing bleaching but still exhibits yellow color as mutually subsidiary colors. Accordingly, these two colors add with each other and become white so that the fabric converts to white.
After the whitening process, due to that, there is a portion of ultraviolet light becoming a visible light to be reflected out with the total reflection amount increased compared to non-processing fabric, the brightness of the treated fabric also improves, becoming whiter. It can also increase the clarity of the colored fabrics. Fluorescent whitening, being different with chemical bleaching, would not damage the fabric color and strength. Though, for fabric and paper of darker background, if they undergo direct brightening treatment without bleaching, can’t obtain good results.
Applications of Optical brightener
Optical brightener (or we can call this process “Optical Whitening”) is mainly used in the textile industry to improve the whiteness of a variety of natural and synthetic fabrics. As the brightening agents used in the textiles get washed away during washing clothes, they are also utilized as an element in the laundry detergents.
In recent years, its application in the fields of paper, plastics, leather, optical toner, synthetic detergent and other daily requirements that is also developing quickly. Like we mentioned before, they are also part of the plastic industry. We can find them in masterbatches that make plastic products, transparent.
“Toseaye Pardis Sabz”, the supplier of organic and inorganic pigments, exports various high-quality masterbatches according to customers’ needs. This includes masterbatches that are very useful for optical whitening and making transparent plastic products.
Source: R & D Unit of Toseaye Pardis Sabz
