Anion-Modified Cellulose Nanofiber Dispersion for Heat Color Stability
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Solution Overview
Problem
Cellulose nanofibers produced by existing methods turn colored when heated, making them unsuitable for industrial applications.
Innovation Solution
A method involving oxidation of cellulose using N-oxyl compounds and bromides/iodides, followed by defibration and addition of sulfite or borate salts as anti-coloring agents to prevent coloring during heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cellulose nanofibers are produced by conventional oxidation methods, then efficient carboxyl group introduction is achieved, but the nanofibers turn colored when heated making them unsuitable for industrial use
Solution Approach 1:
The invention applies preliminary action by adding anti-coloring agents (sulfur dioxide, sulfites, or borates) to the cellulose nanofiber dispersion before thermal processing. This pre-treatment prevents the formation of colored compounds during subsequent heating operations, allowing the nanofibers to maintain their colorless state even after exposure to high temperatures up to 200°C or higher.
Solution Approach 2:
The invention uses anti-coloring agents as intermediary substances that mediate between the cellulose nanofibers and thermal processing conditions. These intermediaries (sulfites or borates) react with or inhibit the formation of colored degradation products, thereby protecting the nanofibers from thermal discoloration without interfering with their fundamental properties or application performance.
2Object-affected harmful factors
If anti-coloring agents are added to prevent thermal coloring, then colorless nanofibers suitable for industrial use are obtained, but the manufacturing process complexity increases
Solution Approach 1:
The invention applies parameter changes by optimizing the concentration ranges of anti-coloring agents (sulfites at 1-30 mass% or borates at 0.1-10 mass% based on cellulose content) and controlling pH conditions during treatment. By adjusting these parameters within specific ranges, the patent achieves effective color prevention while maintaining manageable manufacturing complexity and ensuring the nanofibers retain their desired properties for industrial applications.
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
Manufactures anion-modified cellulose nanofibers that remain colorless when heated, suitable for industrial use.
Implementation Method 1
oxidizing a cellulose material in water using an oxidizing agent in the presence of an N-oxyl compound and a compound selected from the group consisting of bromides and iodides
Implementation Method 2
a treatment of cellulose materials under the coexistence of 2,2,6,6-tetramethyl-1-piperidine-N-oxyradical (hereinafter referred to as TEMPO) and an inexpensive oxidizing agent, sodium hypochlorite, allows an efficient introduction of carboxyl groups
Implementation Method 3
adding an anti-coloring agent selected from sulfite salts to the dispersion liquid of oxidized cellulose nanofibers obtained in (ii)
Data Source
AI summary
The present invention provides a dispersion liquid of anion-modified cellulose nanofibers and a composition of anion-modified cellulose nanofibers that are not colored when heated. Specifically, the dispersion liquid contains anion-modified cellulose nanofibers; an anti-coloring agent selected from the group consisting of borate salts and sulfite salts, or combinations thereof in an amount of 1 to 30 mass% based on an absolute dry mass of the anion-modified cellulose nanofibers; and a solvent.