Optical Brightener Activation Using Reducing Agents in Paper
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Solution Overview
Problem
Conventional methods for improving the brightness of bleached pulp in paper production face limitations, including economic inefficiencies and undesirable color changes due to excessive use of bleaching agents and optical brighteners, which also degrade mechanical properties of paper.
Innovation Solution
The use of reducing agents, such as sulfites and bisulfites, in combination with optical brighteners and chelants, to enhance the brightness and stability of bleached pulp, allowing for improved activation of optical brighteners and reduction of chromophoric structures, thereby increasing brightness and thermal stability while reducing the need for excessive optical brighteners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If bleaching agents are used to improve brightness of pulp, then brightness is improved, but mechanical properties of paper degrade
Solution Approach 1:
The patent introduces optical brighteners as intermediary substances that fluoresce under UV light to compensate for darkness, rather than using bleaching agents that chemically alter and weaken the pulp. The optical brighteners absorb UV radiation and emit visible blue light, creating a brightening effect without degrading the mechanical properties of the paper.
Solution Approach 2:
The patent utilizes the fluorescent properties of optical brighteners to change the perceived color of the paper by adding blue fluorescence that compensates for yellowing, rather than attempting to remove the yellowing through chemical bleaching. This color compensation approach maintains the original pulp structure while achieving the desired brightness effect.
2Illumination intensity
If optical brighteners are used to improve brightness, then brightness is improved, but excessive use results in economic losses and undesirable color changes
Solution Approach 1:
The patent optimizes the concentration and formulation parameters of optical brighteners to achieve maximum brightness enhancement while minimizing excessive fluorescence and color distortion. By carefully controlling the amount and type of optical brightener used, the patent avoids the diminishing returns and adverse color effects that occur with excessive application.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively enhances the brightness and stability of paper products, allowing for higher mechanical pulp usage without compromising quality, reducing production costs, and minimizing undesirable color changes.
Implementation Method 1
adding an effective amount of one or more reducing agents to the bleached pulp, to the stock suspension or on to the sheet
Implementation Method 2
application of optical brighteners changes the appearance of the paper not by altering the light absorbing materials, but instead by adding to the paper additional materials that fluoresce light in their own right
Data Source
AI summary
Compositions and processes that enhance the brightness and improve color of pulp or paper when applied during different stages of the papermaking process involving optical brighteners are identified. Used in combination with optical brighteners and/or chelants the described agents produce a synergistic effect not previously identified in the paper process.