Refined Cellulose Fiber Composition for Paper Strength
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Solution Overview
Problem
Current methods for enhancing the tensile strength and Z-strength of paper or paperboard are energy-intensive and require additional process steps or equipment, limiting their efficiency and integration into pulp mill processes.
Innovation Solution
A refined cellulose fiber composition with a high Schopper-Riegler number and content of fibers longer than 0.2 mm, produced through fractionation and refining of cellulose pulp, which can be integrated into pulp mills without specialized equipment, offering improved strength properties and reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If nanocellulose is used as a strength enhancing agent, then tensile strength and Z-strength are improved, but energy consumption increases significantly
Solution Approach 1:
The invention changes the parameters of cellulose fibers by controlling fibrillation degree and fiber length distribution through refining process. This creates a strength enhancement agent that achieves comparable strength improvement to nanocellulose but with lower energy consumption by optimizing the balance between fiber fragmentation and fibrillation.
Solution Approach 2:
Instead of completely converting cellulose to nanocellulose (excessive action), the invention applies partial refining to create a mixture of fibrillated fibers and fines. This partial action achieves sufficient strength enhancement while consuming significantly less energy than complete nanocellulose production.
2Use of energy by moving object
If enzymatic or chemical pretreatment is applied to reduce energy consumption, then energy costs are reduced, but additional process steps and equipment investments are required
Solution Approach 1:
The invention extracts and eliminates the need for separate enzymatic or chemical pretreatment steps. By using direct mechanical refining with optimized parameters, the process achieves the same energy-saving effect without requiring additional equipment or process complexity.
Solution Approach 2:
The refining process itself is optimized to perform both the fibrillation and energy-efficient processing in a single step. The system uses its own mechanical energy input to achieve the desired fiber modification without needing external chemical or enzymatic assistance.
3Strength
If fiber density is increased to improve Z-strength, then bonded area between fibers increases, but bending stiffness deteriorates
Solution Approach 1:
The invention applies different qualities to different aspects of fiber structure: highly fibrillated surfaces for bonding (improving Z-strength) and preserved fiber length for bulk structure (maintaining bending stiffness). This local differentiation of fiber properties resolves the contradiction between strength and stiffness.
Solution Approach 2:
The refined cellulose fiber composition creates a composite structure within the fiber network, combining long fibrillated fibers for structural integrity with fine fibrils for bonding. This composite approach allows simultaneous optimization of both Z-strength and bending stiffness.
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 refined cellulose fiber composition significantly enhances tensile strength and Z-strength of paper or paperboard while reducing energy demands and eliminating the need for additional processing investments, providing a sustainable alternative for paper and paperboard production.
Implementation Method 1
Strength in fiber and paperboard products can be increased by enhancing fiber-fiber contact, such as by surface fibrillation
Implementation Method 2
Changes that improve fiber-to-fiber bonding are internal and external fibrillation together with fines creation
Implementation Method 3
In the CTMP process, wood chips are impregnated with a lignin softening chemical prior to pressurized refining. This results in softening of lignin
Implementation Method 4
The relationship between density and out-of-plane strength may vary depending on pulp type and densification method. Refining increases strength more than wet pressing
Data Source
AI summary
The present invention relates to a refined cellulose fiber composition useful as a strength enhancing agent for paper and paperboard, wherein the refined cellulose fiber composition has a Schopper-Riegler (SR) number in the range of 80-98 as determined by standard ISO 5267-1, and wherein the refined cellulose fiber composition has a content of fibers having a length >0.2 mm of at least 12 million fibers per gram based on dry weight. The invention further relates to a method for preparing the refined cellulose fiber composition and to pulp paper and paperboard comprising the refined cellulose fiber composition.