Bleached Pulp Brightness Stabilization via Oxidative Treatment
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Solution Overview
Problem
The pulp and paper industry faces significant challenges with brightness loss and thermal yellowing due to existing bleaching processes, which result in economic losses and unsatisfactory results despite the use of chemicals like bleaching agents and optical brighteners.
Innovation Solution
The method involves contacting bleached pulp with oxidizing agents such as hydrogen peroxide and optical brighteners like dilsulfonated stilbene derivatives to enhance brightness and resistance to thermal yellowing, which can be used alone or in combination with other additives during the papermaking process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional bleaching processes are used to achieve white paper products, then brightness is improved, but thermal yellowing and brightness loss occur during storage and processing
Solution Approach 1:
The patent applies preliminary oxidizing treatment to the bleached pulp before the papermaking process to prevent thermal yellowing. By performing the oxidation step in advance (contacting pulp with oxidizing agents like hydrogen peroxide, sodium perborate, or sodium percarbonate), the pulp is pre-protected against brightness loss that would otherwise occur during subsequent thermal processing and storage, eliminating the need for post-bleaching corrections.
2Illumination intensity
If optical brighteners are added to compensate for brightness loss, then brightness is improved, but the amount of chemicals required increases and costs rise
Solution Approach 1:
The patent applies preliminary anti-action by using oxidizing agents to prevent brightness loss before it occurs, rather than adding more optical brighteners to compensate for existing brightness loss. This pre-protective approach counteracts the formation of yellowing substances that would otherwise require additional optical brighteners, thereby reducing the total quantity of chemicals needed while maintaining target brightness levels.
3Reliability
If more bleaching agents and optical brighteners are used to maintain brightness, then brightness stability is improved, but production costs increase significantly
Solution Approach 1:
The patent changes the chemical parameters by substituting conventional bleaching agents with specific oxidizing agents (hydrogen peroxide, sodium perborate, sodium percarbonate) that provide both bleaching and brightness stabilization functions. This parameter change allows achieving brightness stability with reduced chemical quantities, as these oxidizing agents prevent thermal yellowing through a different chemical mechanism that doesn't require subsequent optical brightener addition.
4Illumination intensity
If conventional multistage bleaching processes are employed, then brightness is improved, but process complexity increases
Solution Approach 1:
The patent merges multiple functions into a single oxidizing treatment step. By combining the bleaching function and the thermal yellowing prevention function into one process step (contacting pulp with oxidizing agents), the complex multistage bleaching process is simplified. This consolidation eliminates the need for separate post-bleaching brightness correction steps, reducing overall process complexity while maintaining brightness improvement.
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 stabilizes brightness, improves color, and reduces the need for optical brighteners, leading to cost savings and improved paper quality by enhancing the performance of optical brighteners and maintaining brightness over time.
Implementation Method 1
contacting the bleached pulp material with 0.0005 to 2 weight percent, based on oven-dried pulp, of one or more oxidizing agents excluding organic peroxyacids, wherein the oxidizing agents are selected from the group consisting of hydrogen peroxide, inorganic peroxides, superoxides and peroxide-superoxides
Implementation Method 2
further comprising contacting the bleached pulp material with 0.005 to 2 weight percent, based on oven-dried pulp, of one or more optical brighteners, wherein the optical brighteners are selected from dilsulfonated, tetrasulfonated or hexasulfonated stilbene derivatives
Data Source
AI summary
Oxidative compositions and processes that preserve and enhance the brightness and improve color of pulp or paper when applied during different stages of the papermaking process are identified. The oxidative composition and method maintains and/or enhances brightness, prevents yellowing, and enhances the performance of paper products. Used in combination with optical brighteners and/or chelants the oxidative agents produce a synergistic effect not previously identified in the paper process.