Effect of Optical Brightening Agent (OBA) on Bleaching Process on Paper of Eucalyptus Kraft Pulp

Abstract

In integrated factories of pulp and paper, the bleaching control is made by kappa number and/or brightness. However, the product paper is evaluated and valued for its whiteness. The level of final brightness of pulp certainly affects the demand for optical brighteners in paper manufacturing, nevertheless, there is not a direct correlation between consumption of optical brightener and final brightness, being the method of bleaching pulp, especially from the final stage of bleaching, also important in relation to this demand. Therefore, this study aimed to evaluate the potential of using the parameter whiteness as a tool to control bleaching pulp, instead of the traditional brightness and evaluate the impacts of different methods of bleaching and the pulp final brightness level in action of optical brighteners, to improve their performance. It was observed that the whiteness and brightness of the pulp are highly correlated and that the control of the bleaching plant can be done by any one of these two parameters. It was also concluded that, considering current prices of bleaching reagents and of optical brighteners, it is better to bleach the pulp up to lower brightness values (e.g. 88% ISO) and use larger amounts of optical brighteners to brighten the mass until the whiteness of 130 CIE. This conclusion is valid for whiteness measured before the size press. Further studies are needed to validate this conclusion considering the finished product.

Non‐thermal plasma as an efficient pretreatment to lignocellulosic raw materials

“…The difference in the composition of soluble lignin in different materials too is due to the fact that the lignin of some types of lignin is more reactive, and this is due to the greater presence of Syringyl groups when compared to Guaiacyl, which provides a less condensed and less condensed lignin. more suitable for chemical reactions (Barbosa et al, 2013). Another supposed explanation is in the composition of lignin.…”

Impact of optical brightening agents on alkali‐based inks in packaging: A comparative study on color accuracy

“…OBAs function by absorbing UV light and emitting some of it in the blue visible spectrum to create a whiter appearance affect. 4 Although the UV light is between the 100 and 400 nm wavelength region, the OBAs, typically based on diaminostilbenedisulfonic acid, absorb UV light within the 350-360 nm region and re-emit at 440-500 nm wavelength. 5 The papermaking industry has been adding OBAs at various amounts since 1940s to make the paper appear whiter and improve the color reproduction, as it is regarded as a cost-effective alternative relative to practices of using high-brightness pulp and high-brightness lightscattering coefficient fillers such as precipitated calcium carbonate, ground calcium carbonate and titanium dioxide (TiO 2 ).…”

“…Because of this, producers of all kinds of paper goods, from high‐end fine art papers to household tissue, have resorted to OBAs, which use fluorescence to mask the yellow paper hues. OBAs function by absorbing UV light and emitting some of it in the blue visible spectrum to create a whiter appearance affect 4 . Although the UV light is between the 100 and 400 nm wavelength region, the OBAs, typically based on diaminostilbenedisulfonic acid, absorb UV light within the 350–360 nm region and re‐emit at 440–500 nm wavelength 5 .…”