Lyocell Fiber Viscosity Reduction via Polyethylene Additive
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Solution Overview
Problem
Current lyocell fiber manufacturing is limited by the high viscosity of cellulose, which restricts throughput and increases capital costs, and relies on expensive high-alpha pulps with low hemicellulose content, making it costly and inefficient.
Innovation Solution
Incorporating a polyethylene polymer as an additive in the spinning solution reduces dope viscosity, allowing for higher throughput and producing fibers with both hydrophilic and hydrophobic characteristics using lower-cost, low-alpha pulps with higher hemicellulose content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-alpha pulps with low hemicellulose content are used, then fiber quality is improved, but manufacturing cost increases
Solution Approach 1:
The invention changes the chemical composition parameters of the spinning dope by incorporating specific additives (polyethylene glycol and/or polyvinyl alcohol) that enable the use of low-alpha pulps while maintaining fiber quality. This parameter change allows substitution of expensive high-alpha pulps with cheaper low-alpha pulps without sacrificing performance
Solution Approach 2:
The invention introduces polyethylene glycol and/or polyvinyl alcohol as intermediary substances in the spinning dope. These intermediaries modify the rheological properties and facilitate fiber formation from low-alpha pulps, enabling the use of cheaper raw materials while achieving acceptable fiber quality
2Productivity
If cellulose viscosity is reduced to increase throughput, then production efficiency is improved, but cellulose molecular properties deteriorate
Solution Approach 1:
The invention uses polyethylene glycol and/or polyvinyl alcohol as intermediary substances that modify the rheological properties of the spinning dope. These intermediaries reduce viscosity and improve flow characteristics without degrading cellulose molecular structure, enabling higher throughput while preserving molecular properties
Solution Approach 2:
The invention changes the rheological parameters of the spinning dope by adding specific polymers that reduce viscosity without affecting cellulose degree of polymerization. This allows optimization of flow properties for higher production rates while maintaining cellulose molecular integrity
3Productivity
If polyethylene polymer is added to spinning solution, then dope viscosity is reduced and throughput increases, but fiber composition complexity increases
Solution Approach 1:
The invention optimizes the concentration parameters of polyethylene polymer in the spinning dope to achieve desired viscosity reduction while limiting composition complexity. By controlling the amount of additive (typically 1-20 wt%), the invention balances throughput improvement with compositional simplicity
Solution Approach 2:
The invention applies polyethylene polymer modification locally to specific regions of the spinning dope formulation, allowing viscosity control in the solution phase while maintaining relatively simple fiber composition after spinning. The additive serves its function in the dope but minimizes impact on final fiber structure
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 approach enhances production efficiency, reduces capital costs, and enables the creation of fibers suitable for various applications, including hygienic products and filtration, while maintaining molecular orientation and reducing water retention values.
Implementation Method 1
addition of a polyethylene polymer as an additive to the spinning solution of a lyocell dope results in a significant reduction in dope viscosity
Implementation Method 2
a lyocell fiber with both hydrophilic and hydrophobic characteristics is a resultant product
Data Source
AI summary
Meltblown lyocell fibers incorporating polyolefinic hydrophobic polymers are disclosed. The polymer is distributed fairly uniformly within the fiber and exists as approximately one to two micron diameter domains. The fibers have a high hemicellulose level, show reduced water retention values and have varying diameters depending on processing conditions. The fibers have a brightness of at least 60.