Cellulose Acetate Dry Spinning Solvent Mixture
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The dry spinning of cellulose acetate fibers using DMF as a solvent results in higher operating temperatures, leading to degradation and unacceptable yellowness due to the higher boiling point of DMF, necessitating a process that minimizes color formation while maintaining efficiency.
Innovation Solution
A dry spinning process using a cellulose ester dope with a solvent mixture of N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide, with specific composition constraints to reduce acetone content and minimize polyurethane and nanocrystal presence, to produce fibers with low color formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DMF is used as the spinning solvent to increase spinning capacity, then productivity is improved, but the operating temperature increases leading to fiber degradation and color formation
Solution Approach 1:
The patent changes the chemical parameters of the spinning dope by incorporating specific additives (polyurethane, cellulose nanocrystals, acetone) that modify the thermal and chemical behavior of the DMF-based system. This allows the dope to withstand higher temperatures without degradation, resolving the contradiction between using DMF for high productivity and avoiding color formation.
Solution Approach 2:
The patent introduces polyurethane and cellulose nanocrystals as intermediary substances that mediate between the DMF solvent and the cellulose ester. These intermediaries protect the cellulose ester from thermal degradation at high operating temperatures, enabling the use of DMF for increased spinning capacity without the harmful color formation effect.
2Ease of manufacture
If acetone content is increased to improve spinning performance, then ease of manufacture is improved, but the solvent mixture complexity increases
Solution Approach 1:
The patent creates a composite solvent system combining DMF, acetone, and other components in specific proportions. This composite approach leverages the advantages of each component: DMF provides high boiling point for capacity, acetone improves spinning performance, and the combination achieves both goals while managing complexity through defined composition ranges.
3Object-affected harmful factors
If polyurethane and nanocrystal content is limited to reduce color formation, then fiber quality is improved, but the dope composition flexibility is reduced
Solution Approach 1:
The patent establishes dynamic composition ranges for polyurethane (0.1-10 wt%) and cellulose nanocrystals (0.1-5 wt%) rather than fixed values. This dynamic approach allows optimization of fiber quality by controlling color formation while maintaining sufficient flexibility in dope composition to adapt to different processing conditions and product requirements.
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 cellulose ester fibers with reduced color formation, enabling expanded application opportunities and cost-effective utilization of existing spinning capacity, while maintaining fiber quality and reducing operational costs.
Implementation Method 1
dry spinning a cellulose ester dope through a spinneret to make one or more of the fibers
Data Source
AI summary
A dry spinning system and process are used to produce cellulose ester fibers. The process utilizes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, or mixtures thereof as the dissolution solvent. The process minimizes or avoids discoloration of the fibers.