Ultrafine Fibrous Cellulose via Phosphorylation and Crosslink Hydrolysis
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Solution Overview
Problem
Current methods for producing ultrafine fibrous cellulose with high phosphoric acid group content and low crosslinked structure formation are inefficient, requiring multiple phosphorylation steps and high energy consumption, which complicates the production process and reduces the polymerization degree of the cellulose.
Innovation Solution
A method involving the introduction of phosphoric acid groups into cellulose fibers using a phosphorylating reagent in the presence of urea, followed by crosslink formation, hydrolysis, and mechanical treatment to break crosslinks, resulting in ultrafine fibrous cellulose with high phosphoric acid content and controlled crosslinked structures, thereby enhancing energy efficiency and maintaining high polymerization degrees.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple phosphorylation steps are performed to increase phosphoric acid group content, then the phosphoric acid group content increases, but the production process complexity increases and energy consumption increases
Solution Approach 1:
The patent combines the phosphorylation step and crosslinking step into a single integrated process. By using phosphoric acid or phosphorous acid directly on cellulose fibers, both phosphoric acid group introduction and crosslink structure formation occur simultaneously, eliminating the need for separate multiple phosphorylation steps while achieving high phosphoric acid group content
Solution Approach 2:
The patent performs crosslinking as a preliminary action before mechanical treatment. By forming crosslink structures during the phosphorylation process, the cellulose fibers are pre-prepared for subsequent mechanical fibrillation, which reduces the energy required during the actual fibrillation step while maintaining high phosphoric acid group content
2Quantity of substance
If multiple phosphorylation steps are performed to increase phosphoric acid group content, then the phosphoric acid group content increases, but the energy consumption increases
Solution Approach 1:
The patent merges phosphorylation and crosslinking into one step, reducing the total number of processing steps and associated energy consumption. The simultaneous formation of phosphoric acid groups and crosslink structures eliminates redundant heating and chemical treatment cycles
Solution Approach 2:
The patent controls the pH and temperature parameters during the single phosphorylation-crosstlinking step to optimize both phosphoric acid group introduction and crosslink formation. By maintaining specific pH ranges (using buffers or controlled acid addition) and temperature conditions, the process achieves high phosphoric acid content with minimal energy input
3Strength
If crosslinked structures are formed via phosphoric acid groups, then the mechanical strength improves, but the polymerization degree decreases
Solution Approach 1:
The patent forms crosslink structures during phosphorylation but deliberately limits the extent of crosslinking to maintain adequate polymerization degree. By controlling the amount of phosphoric acid/crosslinking conditions, sufficient crosslinks are formed to provide mechanical strength while avoiding excessive crosslinking that would reduce polymerization degree below acceptable levels
Solution Approach 2:
The crosslinking is performed as a preliminary step before mechanical fibrillation. This timing allows crosslink structures to form and provide structural integrity, while the subsequent mechanical treatment breaks these crosslinks to achieve the desired ultrafine fiber morphology without permanently reducing the polymerization degree of the final product
4Length of moving object
If mechanical treatment is performed to reduce fiber diameter to ultrafine scale, then the fiber diameter decreases, but the energy consumption increases
Solution Approach 1:
The patent performs phosphorylation and crosslinking as preliminary actions before mechanical fibrillation. The crosslink structures formed during this phase act as temporary scaffolds that facilitate controlled fibrillation, reducing the mechanical energy required to achieve ultrafine fiber diameters while maintaining process efficiency
Solution Approach 2:
The patent modifies the physical-chemical parameters of the cellulose fibers through phosphorylation before mechanical treatment. The introduction of phosphoric acid groups and temporary crosslinking changes the fiber surface properties and internal structure, making the fibers more susceptible to mechanical fibrillation and reducing the energy required to achieve ultrafine dimensions
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 method allows for the efficient production of ultrafine fibrous cellulose with high phosphoric acid content and low crosslinked structures, achieving high viscosity in slurry form and excellent mechanical strength in sheet form, while suppressing yellowing and maintaining high polymerization degrees.
Implementation Method 1
introducing phosphoric acid groups into cellulose fibers by allowing a phosphorylating reagent to react with a fiber raw material comprising cellulose in the presence of urea and/or a derivative thereof
Implementation Method 2
forming crosslinked structures via the phosphoric acid groups
Implementation Method 3
breaking some or all of the crosslinked structures to obtain crosslink-broken phosphorylated cellulose fibers
Implementation Method 4
the (B) is performing the hydrolysis of the crosslinked structures in an aqueous solvent with pH 3 or more at a temperature of 80°C or higher
Implementation Method 5
performing a mechanical treatment on the crosslink-broken phosphorylated cellulose fibers to obtain fibrous cellulose having a fiber width of 1000 nm or less
Implementation Method 6
allowing a phosphorylating reagent to react with a fiber raw material comprising cellulose in the presence of urea and/or a derivative thereof
Data Source
Figure 1
AI summary
It is an object of the present invention to provide a method for producing ultrafine fibrous cellulose, which is capable of efficiently obtaining ultrafine fibrous cellulose having phosphoric acid groups with a high yield. The present invention relates to a method for producing fibrous cellulose having a fiber width of 1000 nm or less, comprising: a (A) of introducing phosphoric acid groups into cellulose fibers to form crosslinked structures via the phosphoric acid groups, thereby obtaining crosslinked phosphorylated cellulose fibers, a (B) of breaking some or all of the crosslinked structures to obtain crosslink-broken phosphorylated cellulose fibers, and a (C) of performing a mechanical treatment on the crosslink-broken phosphorylated cellulose fibers to obtain fibrous cellulose having a fiber width of 1000 nm or less, wherein, in the (A), crosslinked structures in an amount of 0.05 mmol/g or more and 2.0 mmol/g or less are formed, and the (B) is a step of performing the hydrolysis of the crosslinked structures in an aqueous solvent with pH 3 or more.