Cellulose Triacetate Separation Membrane with High Tensile Elasticity

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Solution Overview

Problem

Conventional cellulose-based separation membranes face challenges in achieving high separation and permeation performance while maintaining sufficient membrane strength, with existing methods either compromising on separation performance or membrane strength during the production process.

Innovation Solution

A separation membrane composed of cellulose esters with specific degrees of substitution, combined with plasticizers and high-molecular-weight polyalkylene glycols, and antioxidants, which are processed to achieve a balance of thermal flowability and strength, resulting in a membrane with improved tensile elasticity and permeation flux.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a hollow fiber membrane is obtained by melt-spinning a mixture of water-soluble polyhydric alcohol and cellulose diacetate, then high permeation performance is achieved, but separation performance is low and membrane strength is insufficient due to yarn breakage during spinning

Engineering Contradiction:
Improvepermeation performanceVSAvoidseparation performance
Core Design Contradiction:
Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the membrane material by using cellulose triacetate instead of cellulose diacetate, and by adjusting the molecular weight and composition ratios of the polyhydric alcohol and plasticizer components. This parameter change enables the membrane to achieve both high permeation performance and high separation performance simultaneously while maintaining structural integrity during spinning.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by combining cellulose triacetate with specific polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol) and plasticizers in optimized ratios. This composite structure creates a membrane that exhibits synergistic properties, achieving both high permeation and high separation performance while preventing yarn breakage during the spinning process.

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If a hollow fiber membrane is obtained by discharging a solution through an arc-shaped nozzle and immersing in a coagulating bath, then excellent separation and permeation performance is achieved, but membrane strength is low

Engineering Contradiction:
Improveseparation performanceVSAvoidmembrane strength
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The patent changes the chemical composition parameters by using cellulose triacetate with specific degrees of substitution and combining it with polyhydric alcohols having specific molecular weights (200-1000). This parameter optimization strengthens the membrane structure while preserving the excellent separation and permeation performance achieved through the solution discharge and coagulating bath process.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If spinning is performed at high draft to improve productivity, then production efficiency increases, but yarn breakage occurs causing insufficient membrane strength

Engineering Contradiction:
Improvespinning efficiencyVSAvoidmembrane strength
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The patent optimizes the composition parameters of the spinning solution, specifically using cellulose triacetate with controlled degrees of substitution and combining it with polyhydric alcohols of specific molecular weights. This parameter optimization enhances the mechanical strength of the forming yarn, allowing high-draft spinning to be performed without excessive yarn breakage, thus improving productivity while maintaining membrane strength.

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

The membrane exhibits excellent separation and permeation performance, along with high membrane strength, making it suitable for various applications including water treatment and gas separation, while maintaining stability and efficiency.

Implementation Method 1

they have permeation performance due to their hydrophilicity

Methodology Applied
Scientific EffectHydrophilicity: Hydrophile

Implementation Method 2

having excellent separation performance and permeation performance

Methodology Applied
Scientific EffectPermeation: Permeation

Data Source

PatentUS10888822B2Separation membrane
Publication Date: 2021.01.12 TORAY INDUSTRIES INC

AI summary

The present invention provides a separation membrane having excellent separation performance and permeation performance, having high membrane strength, and mainly including a cellulose-based resin. The present invention relates to a separation membrane containing a cellulose ester and having a tensile elasticity of 1,500 to 6,500 MPa.