Viscosity Controlled Cellulosic Material via Continuous Plasticization
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Solution Overview
Problem
Current methods for manufacturing cellulosic materials, such as viscose filaments, face challenges in achieving controlled viscosity and efficiency, particularly in using wood-based cellulosic materials, which often result in environmental issues and high production costs.
Innovation Solution
A continuous process involving a cellulose-water mixture treated with bleached kraft or sulfite pulp at controlled temperatures and pressures, followed by a depressurization step without steam explosion, to produce viscosity-controlled cellulosic material with a viscosity range of 150-500 ml/g and R18 solubility between 60-87%, utilizing a system with a continuous reactor and recycling of filtrate to reduce chemical consumption and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wood-based cellulosic material is used to produce cellulosic material with controlled viscosity, then production efficiency and cost-effectiveness improve, but achieving precise viscosity control and maintaining fiber integrity becomes difficult
Solution Approach 1:
The patent applies parameter changes by systematically adjusting temperature (100-200°C), pressure (1-15 bar), and treatment time (5-120 minutes) during the plasticization step to achieve precise control over the viscosity of the cellulosic material. The continuous process allows real-time modification of these parameters to optimize both production efficiency and viscosity control, transforming wood-based material into products with specific viscosity ranges (150-500 ml/g) suitable for different applications.
2Productivity
If steam explosion is used for depressurization to increase production speed, then productivity improves, but fiber integrity is destroyed
Solution Approach 1:
The patent inverts the conventional approach by avoiding steam explosion entirely. Instead of using violent depressurization to speed up production, the invention employs controlled, gradual depressurization followed by washing and drying steps. This reverse approach maintains fiber integrity while still achieving efficient production through the continuous processing mode, proving that gentler methods can be more effective than violent ones.
3Manufacturing precision
If chemical treatment is applied to wood-based material to achieve desired viscosity, then viscosity control improves, but chemical consumption and environmental impact increase
Solution Approach 1:
The patent applies self-service by utilizing the natural properties of wood-based cellulosic material and water to achieve viscosity control through physical plasticization rather than heavy chemical treatment. The continuous process with controlled temperature and pressure enables the material to self-transform into the desired viscosity range with minimal chemical addition, reducing environmental impact while maintaining precise control over the final product properties.
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 process effectively produces cellulosic material with improved viscosity control, reduced chemical usage, and enhanced production efficiency, maintaining fiber integrity and optical properties, while being environmentally friendly and cost-effective.
Implementation Method 1
treating the formed cellulose-water mixture in a plasticization step at a temperature between 130°C and 200°C
Implementation Method 2
feeding hot water and/or water steam to the cellulose-water mixture
Implementation Method 3
feeding hot water and/or water steam to the cellulose-water mixture
Implementation Method 4
depressurizing the treated mixture after the plasticization step in a depressurizing step in a controlled manner
Data Source
Figure 1a~1b
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Figure 3
AI summary
The invention relates to method for producing viscosity controlled cellulosic material having a viscosity value in a range between 150 ml/g and 500 ml/g in a continuous process, the method comprising the following steps: i) forming a cellulose-water mixture (15) comprising water and chemically treated wood-based cellulosic material, the cellulose-water mixture (15) having a dry matter content between 3% and 20%, ii) treating the formed cellulose-water mixture (15) in a plasticization step (100) at a temperature between 130°C and 200°C, and a pressure between 3 bars and 15 bars, at least 5 minutes and 120 minutes at the most, while mixing the cellulose-water mixture (15), and feeding hot water and/or water steam to the cellulose-water mixture, thereby obtaining a treated mixture (18), and iii) depressurizing the treated mixture (18) in a depressurizing step (105) in a controlled manner, thereby obtaining the viscosity controlled cellulosic material (20). This invention further relates to a viscosity controlled cellulosic material and a system for producing viscosity controlled cellulosic material.