Paper-Derived Carbon Fibre Through Direct Phosphoric Acid Dissolution

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Solution Overview

Problem

Existing methods for manufacturing carbon fibers from cellulose require complex pre-treatment steps and high energy input, making them costly and environmentally inefficient, while there is a need for renewable and cost-effective alternatives.

Innovation Solution

A method to directly dissolve ground paper products in an aqueous phosphoric acid solution without pre-treatment, followed by solvent spinning and carbonization, to produce carbon fibers with high mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional pre-treatment steps (cooking, washing, pulping) are implemented to manufacture cellulose fibres from paper, then the quality of cellulose precursor is improved, but the process complexity and energy consumption increase significantly

Engineering Contradiction:
Improvecellulose fibre qualityVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The paper is ground into fine particles before dissolution to increase surface area and facilitate direct dissolution in phosphoric acid without requiring pre-treatment steps. This preliminary size reduction enables the simplification of subsequent processing steps while maintaining cellulose quality.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention changes the chemical environment by using phosphoric acid as a dissolution medium at controlled temperatures (50-80°C), which allows direct dissolution of ground paper without the need for conventional cooking or pulping steps. This parameter change fundamentally simplifies the process while preserving cellulose integrity.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If high temperature processing is applied to dissolve paper and form cellulose fibres, then dissolution efficiency is improved, but energy consumption increases

Engineering Contradiction:
Improvedissolution efficiencyVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The invention uses phosphoric acid as a dissolution medium that enables effective cellulose dissolution at moderate temperatures (50-80°C), significantly reducing the energy input required compared to conventional high-temperature methods. This parameter change maintains dissolution efficiency while dramatically lowering energy consumption.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If waste paper is used as raw material instead of purified cellulose, then production cost is reduced, but the presence of additives and fillers may degrade fibre quality

Engineering Contradiction:
Improveproduction costVSAvoidfibre quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention uses phosphoric acid dissolution followed by controlled precipitation to selectively recover cellulose from waste paper, leaving behind mineral fillers and organic additives in the solution. This parameter change enables quality cellulose fibre production from low-cost waste paper while filtering out impurities.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The dissolution and precipitation process extracts pure cellulose from the complex matrix of waste paper, separating it from unwanted additives and fillers. This extraction mechanism enables the use of low-cost waste material while producing high-quality cellulose fibres suitable for carbon fibre production.

Inventive Principle:
Principle #2Taking out (Extraction)

4Manufacturing precision

If multiple pre-treatment steps are implemented to remove additives from paper, then fibre purity is improved, but manufacturing time and cost increase

Engineering Contradiction:
Improvefibre purityVSAvoidmanufacturing time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

Grinding the paper into fine particles before dissolution increases the surface area and facilitates rapid dissolution of cellulose in phosphoric acid. This preliminary action reduces the time required for subsequent processing steps while enabling effective separation of cellulose from impurities through controlled precipitation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The controlled precipitation process, triggered by adding water or non-solvents to the phosphoric acid solution, rapidly separates pure cellulose from impurities in a single step. This parameter change enables high-purity fibre production without requiring multiple sequential treatment steps, significantly reducing manufacturing time.

Inventive Principle:
Principle #35Parameter changes

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 produces carbon fibers with tensile strength greater than 1,200 MPa and Young's modulus of 75 GPa, suitable for various applications, at a significantly lower cost and environmental impact.

Implementation Method 1

dissolving the ground material in an aqueous phosphoric acid solution acting as a solvent solution, in which the cellulose is soluble

Methodology Applied
Scientific EffectDissolution: Solvation

Implementation Method 2

forming a cellulose-based fibre by solvent spinning

Methodology Applied
Scientific EffectPhase separation: Phase Change

Implementation Method 3

carbonising the resulting cellulose-based fibre to form a carbon fibre

Methodology Applied
Scientific EffectCarbonization: Pyrolysis

Data Source

PatentUS12404381B2Method for making a carbon fibre from a paper product
Publication Date: 2025.09.02 CENT TECHNOLOGIQUE NOUVELLE- AQUITAINE COMPOSITES & MATERIAUX AVANCES

AI summary

Disclosed is a method for making a carbon fibre from a paper product. The method includes preparing a cellulose-based fibre by crushing the paper product, dissolving the crushed material obtained in an aqueous phosphoric acid solution to form a spinning solution, and forming a cellulose-based continuous fibre by use of a solvent spinning process. The cellulose fibre formed in this way is subjected to carbonisation treatment in order to form a carbon fibre.