Polyamide Filament Strength Retention After Water Absorption

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Solution Overview

Problem

Polyamide resin-based filaments used in fishing lines face challenges in maintaining high linear strength and knot strength after water absorption treatment.

Innovation Solution

A filament containing a polyamide resin synthesized from xylylene diamine and an α,ω-linear aliphatic dicarboxylic acid with 11 to 14 carbons, which maintains 70 mol % or more of constituent units from these components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional polyamide resins are used in fishing lines, then the filaments can be manufactured with standard properties, but the maintenance rate of linear strength and knot strength after water absorption treatment deteriorates

Engineering Contradiction:
Improvemaintenance rate of linear strength and knot strength after water absorption treatmentVSAvoidlinear strength and knot strength after water absorption treatment
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention changes the chemical composition parameters of the polyamide resin by specifying that 70 mol% or more of the diamine constituent units are derived from xylylene diamine and 70 mol% or more of the dicarboxylic acid constituent units are derived from α,ω-linear aliphatic dicarboxylic acid having 11 to 14 carbons. This parameter change in molecular structure improves the maintenance rate of strength properties after water absorption treatment while maintaining manufacturability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite polyamide resin system combining xylylene diamine units with α,ω-linear aliphatic dicarboxylic acid units (11-14 carbons). This composite molecular structure creates a filament that maintains high linear strength and knot strength after water absorption, resolving the contradiction between reliability and strength retention

Inventive Principle:
Principle #40Composite materials

2Reliability

If polyamide resin is used to ensure durability in fishing lines, then the filament can withstand mechanical stress, but the strength maintenance after water absorption deteriorates due to water uptake

Engineering Contradiction:
Improvedurability in fishing line applicationVSAvoidstrength maintenance after water absorption treatment
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention modifies the molecular parameters of the polyamide resin by incorporating xylylene diamine (70 mol% or more) and α,ω-linear aliphatic dicarboxylic acid with 11-14 carbons (70 mol% or more). This parameter optimization reduces water absorption effects while maintaining durability, allowing the filament to maintain 90% or more of its linear strength and 70% or more of its knot strength after water absorption treatment

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention introduces specific local chemical structure characteristics into the polyamide resin - the xylylene diamine units provide aromatic ring structures that enhance strength maintenance, while the specific chain-length dicarboxylic acid units (11-14 carbons) provide optimal balance between durability and water resistance at the molecular level

Inventive Principle:
Principle #3Local quality

Data Source

PatentUS12320038B2Filament and fishing line
Publication Date: 2025.06.03 MITSUBISHI GAS CHEM CO INC

AI summary

Provided are a filament having, after a water absorption treatment, a high maintenance rate of linear strength and a high maintenance rate of knot strength, and a fishing line. The filament contains a polyamide resin (A), and the polyamide resin (A) is constituted from a constituent unit derived from a diamine and a constituent unit derived from a dicarboxylic acid, and 70 mol % or more of the constituent units derived from a diamine are derived from xylylene diamine, and 70 mol % or more of the constituent units derived from a dicarboxylic acid are derived from an α,ω-linear aliphatic dicarboxylic acid having from 11 to 14 carbons.