Kraft Pulp Oxidation for Carboxylic Functionality Without Fiber Degradation
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Solution Overview
Problem
Current methods for modifying cellulose fibers to improve carboxylic and aldehydic functionality often degrade the fibers, leading to loss of length and brightness, and require costly multi-step processes or the use of expensive materials like cotton or high alpha content sulfite pulps, limiting their applicability in various downstream applications.
Innovation Solution
A method involving catalytic oxidation of cellulose fibers with iron or copper in the bleaching process, specifically in the fourth stage of a five-stage bleaching sequence, to enhance carboxylic and aldehydic functionality without degrading the fibers, maintaining fiber length and brightness, and allowing for the production of low or ultra-low degree of polymerization fibers suitable for absorbent products and cellulose derivatives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional oxidation methods are used to improve carboxylic and aldehydic functionality, then functionality is enhanced, but fiber length and brightness are degraded
Solution Approach 1:
The patent applies parameter changes by conducting oxidation at controlled temperatures (40-80°C) and pH levels (2-5) during specific bleaching stages, and by controlling the dosage and addition timing of oxidizing agents to enhance functionality while preserving fiber length
Solution Approach 2:
The oxidation treatment is performed preliminarily during the bleaching process (specifically in the E1 or E2 stages) before final fiber processing, allowing functional groups to be introduced early when the fiber is more accessible, thereby achieving enhanced functionality without subsequent fiber degradation
2Quantity of substance
If multi-step oxidation processes are used to enhance functionality, then carboxylic and aldehydic content increases, but process complexity and cost increase
Solution Approach 1:
The patent merges the oxidation step with the existing bleaching process by using the same equipment and combining chemical treatments, thereby achieving enhanced functionality without adding separate oxidation equipment or independent process stages
Solution Approach 2:
The bleaching process is made multi-functional by simultaneously achieving both bleaching and oxidation objectives through the addition of oxidizing agents during bleaching stages, eliminating the need for separate dedicated oxidation equipment and processes
3Reliability
If expensive materials like cotton or high alpha content sulfite pulps are used, then fiber quality is improved, but production cost increases
Solution Approach 1:
The patent uses conventional, readily available kraft pulp as a substitute for expensive specialty pulps, achieving comparable or superior fiber quality through chemical modification (oxidation) rather than relying on inherently high-quality but costly raw materials
Solution Approach 2:
The patent transforms conventional kraft pulp into a high-quality fiber by changing its chemical parameters through oxidation, introducing carboxylic and aldehydic functional groups that enhance fiber properties without requiring expensive raw material substitutions
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
The method produces cellulose fibers with improved odor control, compressibility, and brightness, maintaining fiber length and suitability for a wide range of applications, including absorbent products and cellulose derivatives, while reducing production costs and environmental impact.
Implementation Method 1
catalytic oxidation of cellulose fibers with iron or copper
Implementation Method 2
oxidizing the cellulose fiber with iron or copper and hydrogen peroxide
Implementation Method 3
oxidizing the cellulose fiber with iron or copper and hydrogen peroxide
Implementation Method 4
the fiber can be treated by acid or alkaline hydrolysis to further reduce the degree of polymerization
Data Source
AI summary
A modified kraft pulp fiber with unique properties is provided. The modified fiber can be a modified bleached kraft fiber that is almost indistinguishable from its conventional counterpart, except that it has a low degree of polymerization (DP). Methods for making the modified fiber and products made from it are also provided. The method can be a one step acidic, iron catalyzed peroxide treatment process that can be incorporated into a single stage of a multi-stage bleaching process. The products can be chemical cellulose feedstocks, microcrystalline cellulose feedstocks, fluff pulps and products made from them.