Liquid-Crystalline Polyester Viscosity Control for Fiberization

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Solution Overview

Problem

Conventional liquid crystalline aromatic polyesters experience increased viscosity when kept in a molten state, making it difficult to fiberize while maintaining properties such as low dielectric loss and high heat resistance.

Innovation Solution

A liquid-crystalline polyester with a structural unit composition of 40% or more 2,6-naphthalenediyl groups, along with specific aromatic units, and a flow initiation temperature between 280 to 320°C, which inhibits viscosity increase and allows for easy fiberization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional liquid crystalline aromatic polyesters are kept in a molten state for fiberization, then the fiberization process can be performed, but the viscosity increases remarkably making it difficult to fiberize

Engineering Contradiction:

Improveease of fiberizationVSAvoidviscosity stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical composition parameters of the polyester by incorporating specific structural units (2-hydroxy-6-naphthoic acid, phenylene diol, 2,6-naphthalene dicarboxylic acid, and phenylene dicarboxylic acid) in controlled ratios. This compositional parameter change results in a polyester with a flow initiation temperature of 280-320°C and stable viscosity characteristics during molten state, enabling easy fiberization while maintaining low dielectric loss and high heat resistance.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If liquid crystalline aromatic polyesters with low dielectric loss and high heat resistance are obtained, then excellent electronic part properties are achieved, but fiberization becomes difficult due to viscosity increase

Engineering Contradiction:

Improvelow dielectric loss and high heat resistanceVSAvoidease of fiberization

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent optimizes the compositional parameters by controlling the ratios of specific structural units to achieve a flow initiation temperature of 280-320°C and stable melt viscosity. This parameter optimization allows the polyester to maintain its excellent electrical and thermal properties while becoming suitable for fiberization processes.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structural composition by combining four different structural units (2-hydroxy-6-naphthoic acid, phenylene diol, 2,6-naphthalene dicarboxylic acid, and phenylene dicarboxylic acid) in specific ratios. This composite structure synergistically provides both the excellent electrical/thermal properties and the improved processability for fiberization.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS8071711B2Polyester for producing fiber, and fiber and non-woven fabric using the same

Publication Date: 2011.12.06 SUMITOMO CHEM CO LTD

AI summary

The present invention provides a liquid-crystalline polyester having a structural unit represented by the formula (i), a structural unit represented by the formula (ii) and a structural unit represented by the formula (iii):wherein Ar1 is, at each occurrence, a member selected from the group consisting of a 2,6-naphthalenediyl group, a 1,4-phenylene group and a 4,4′-biphenylene group; and Ar2 and Ar3 are, at each occurrence, a member selected from the group consisting of a 2,6-naphthalenediyl group, a 1,4-phenylene group, a 1,3-phenylene group and a 4,4′-biphenylene group; wherein 40% by mole or more of all the groups Ar1, Ar2 and Ar3 are 2,6-naphthalenediyl groups; and wherein the polyester has a flow initiation temperature of from about 280 to about 320° C.