PTFE Real Twist Yarn Circular Cross-Section Snagging

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Solution Overview

Problem

Conventional methods for producing polytetrafluoroethylene (PTFE) real twist yarns result in fibers with low strength, snagging issues, and non-circular cross-sections, making them unsuitable for sewing and dental floss applications.

Innovation Solution

A PTFE real twist yarn with a circular cross-section is produced by twisting a PTFE multi-filament slit yarn using a yarn-twisting machine, achieving a circularity ratio of 10/8 to 10/10, average fineness of 1.5 to 200 dtex, and a twist coefficient of 10000 to 35000, suitable for sewing yarns and dental floss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If PTFE fibers are produced by emulsion spinning followed by sintering, then PTFE fibers can be obtained, but the strength of the fibers is low and production cost is high

Engineering Contradiction:

Improvefiber strengthVSAvoidproduction cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The invention changes the production parameters by using slitting and stretching processes instead of emulsion spinning and sintering. The PTFE film is slit into tapes and then stretched to high degrees, transforming the production methodology and achieving both low cost and high strength simultaneously

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the thermal-sintering mechanism with a mechanical stretching mechanism. Instead of using heat to sinter PTFE particles into fibers, the invention uses mechanical stretching of slitted PTFE film to produce high-strength fibers, eliminating the need for high-temperature sintering

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If PTFE film is slitted into minute width and stretched to high degree, then high-strength PTFE fibers can be obtained, but the end portion of the tape tends to be fibrillated and some fibers get ruptured

Engineering Contradiction:

Improvefiber strengthVSAvoidfiber integrity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention applies preliminary action by conducting surface treatment on the PTFE film before slitting. This pre-treatment prevents fibrillation at the tape ends during subsequent stretching, maintaining fiber integrity while achieving high strength

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The surface treatment acts as a cushioning measure that prevents the harmful fibrillation effect from occurring in the first place. By treating the surface beforehand, the invention protects the tape ends from rupturing during the stretching process

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If PTFE film is helically rolled to form yarn, then yarn can be obtained, but the yarn has a spiral seam on its surface causing it to get snagged easily and be vulnerable to friction

Engineering Contradiction:

Improveyarn formationVSAvoidsnagging and friction

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The invention transforms the spiral seam structure into a smooth cylindrical surface by using circular motion during the stretching process. The tape is stretched while rotating, which eliminates the spiral seam and creates a smooth surface that resists snagging and friction

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention extracts and eliminates the harmful spiral seam feature from the yarn structure. By using circular stretching, the spiral seam is removed entirely, leaving only a smooth cylindrical surface

Inventive Principle:

Principle #2Taking out (Extraction)

4Adaptability or versatility

If conventional PTFE real twist yarns are made into sewing yarns, then sewing yarns can be produced, but they get snagged on sewing machine needle easily due to spiral joints

Engineering Contradiction:

Improvesewing applicationVSAvoidsnagging on needle

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The invention creates a smooth cylindrical surface by circular stretching, which eliminates the spiral joints that cause snagging. This smooth surface makes the yarn suitable for sewing applications where it passes through needle eyes without catching

Inventive Principle:

Principle #14Spheroidality (Curvature)

5Object-affected harmful factors

If PTFE filament surface area is increased by towing, then friction resistance is improved, but the filament has a flat cross-section

Engineering Contradiction:

Improvefriction resistanceVSAvoidcross-section shape

Core Design Contradiction:

Object-affected harmful factorsVSShape

Solution Approach 1:

The invention uses circular stretching to create a smooth cylindrical surface that provides friction resistance while maintaining a circular cross-section. This eliminates the flat cross-section problem of towed filaments while preserving the friction-resistant surface

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS8316629B2Polytetrafluoroethylene real twist yarn and method of producing the same

Publication Date: 2012.11.27 YEU MING TAI CHEM INDAL

AI summary

The PTFE real twist yarn of the present invention is a PTFE real twist yarn obtained by twisting a polytetrafluoroethylene (PTFE) multi-filament slit yarn. The yarn has a circular cross-section with a circularity in the range of 10/8 to 10/10, where the circularity is expressed by the ratio between the major axis width and the minor axis width, the average fineness of filaments is in the range of 1.5 to 200 dtex, a fineness D is in the range of 50 to 6000 dtex, and a twist coefficient K expressed by Formula (1) is in the range of 10000 to 35000:twist coefficient K=number of twists T×(the fineness D of the PTFE real twist yarn)1/2 (1)where the number of twists T denotes the number of twists per meter and the fineness D is a total fineness.