Liquid crystalline polyester fiber and method for producing the same

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Solution Overview

Problem

Existing methods for preventing fusion during heat treatment of liquid crystalline polyester fibers, such as using inorganic particles or organic liquids, face issues like residue damage and environmental concerns, as it is difficult to remove these agents without harming the fibers.

Innovation Solution

Attaching water-soluble salts like potassium iodide or sodium chloride to the fibers before heat treatment, which can be easily washed off, thereby preventing fusion and maintaining high tensile strength with minimal residue.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If inorganic particles are attached to prevent fusion during heat treatment, then inter-fiber fusion is prevented, but inorganic particles remain on the fiber surface causing damage and deteriorating mechanical properties

Engineering Contradiction:

Improveprevention of inter-fiber fusionVSAvoidinorganic particle residue damage

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention changes the chemical composition parameter of the anti-fusion agent from inorganic particles to water-soluble salts (such as potassium iodide, sodium chloride). This parameter change allows the agent to be easily removed by washing after heat treatment, eliminating the harmful residue effect while maintaining the fusion prevention function during processing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The water-soluble salt anti-fusion agent is deliberately applied, serves its protective function during heat treatment, and then is completely removed by washing. This temporary use and subsequent removal of the agent eliminates long-term harmful effects while achieving the necessary protective function during critical processing.

Inventive Principle:

Principle #34Discarding and recovering

2Reliability

If organic liquids such as silicone oil are used as heating medium, then inter-fiber fusion is prevented, but the heating medium is difficult to remove and requires organic solvents for washing

Engineering Contradiction:

Improveprevention of inter-fiber fusionVSAvoidheating medium residue and environmental risk

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention changes the solubility parameter of the anti-fusion agent from organic-soluble (silicone oil) to water-soluble (potassium iodide, sodium chloride). This fundamental parameter change enables removal by water washing instead of requiring organic solvents, eliminating environmental risks and making the process safer and more economical.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention substitutes the washing mechanism from organic solvent-based removal to water-based removal. This substitution replaces harmful chemical processes with a simpler, safer, and more environmentally friendly water washing process, achieving the same cleaning function without the drawbacks of organic solvent use.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Strength

If heat treatment is applied to improve strength and modulus, then fiber mechanical properties are enhanced, but single filaments fuse causing stress conversion and fiber fragility

Engineering Contradiction:

Improvetensile strength and modulus of elasticityVSAvoidfiber cohesion and fragility

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention applies the water-soluble salt anti-fusion agent to the fiber surface before heat treatment. This preliminary protective action prevents filament fusion during the subsequent heat treatment process, allowing the fiber to achieve enhanced strength and modulus without developing the fragility that would result from stress conversion during uncontrolled fusion.

Inventive Principle:

Principle #10Preliminary action

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 method achieves high tensile strength and low ash content, reducing defects like single-yarn breakage and fibrillation, and enhances processability by preventing inter-fiber fusion and minimizing environmental impact.

Implementation Method 1

a method of attaching inorganic particles before heat treatment

Methodology Applied

Scientific EffectPhysical barrier effect:

Implementation Method 2

the water-soluble salts are washed off

Methodology Applied

Scientific EffectDissolution: Solvation

Data Source

PatentUS11686017B2Liquid crystalline polyester fiber and method for producing the same

Publication Date: 2023.06.27 KURARAY CO LTD

AI summary

A liquid-crystal polyether fiber with high tensile strength has an ash content of 0.3 percent by weight or less, a degree of fusion (f) of 3 or less, and a tensile strength of 18 cN/dtex or more. The liquid-crystal polyether fiber has few residues of an anti-fusion agent and causes no fusion between filaments.