Saturday, July 4, 2015

Characteristics of Filament Yarn[1]
Art Resource

Marie-Therese Wisniowski

Preamble
This is the forty-first post in the "Art Resource" series, specifically aimed to construct an appropriate knowledge base in order to develop an artistic voice in ArtCloth.

Other posts in this series are:
Glossary of Terms and Fabrics
Units Used in Dyeing and Printing of Fabrics
Occupational, Health & Safety
A Brief History of Color
The Nature of Color
Psychology of Color
Color Schemes
The Naming of Colors
The Munsell Color Classification System
Methuen Color Index and Classification System
The CIE System
Pantone - A Modern Color Classification System
Optical Properties of Fiber Materials
General Properties of Fiber Polymers and Fibers - Part I
General Properties of Fiber Polymers and Fibers - Part II
General Properties of Fiber Polymers and Fibers - Part III
General Properties of Fiber Polymers and Fibers - Part IV
General Properties of Fiber Polymers and Fibers - Part V
Protein Fibers - Wool
Protein Fibers - Speciality Hair Fibers
Protein Fibers - Silk
Protein Fibers - Wool versus Silk
Timelines of Fabrics, Dyes and Other Stuff
Cellulosic Fibers (Natural) - Cotton
Cellulosic Fibers (Natural) - Linen
Other Natural Cellulosic Fibers
General Overview of Man-Made Fibers
Man-Made Cellulosic Fibers - Viscose
Man-Made Cellulosic Fibers - Esters
Man-Made Synthetic Fibers - Nylon
Man-Made Synthetic Fibers - Polyester
Man-Made Synthetic Fibers - Acrylic and Modacrylic
Man-Made Synthetic Fibers - Olefins
Man-Made Synthetic Fibers - Elastomers
Man-Made Synthetic Fibers - Mineral Fibers
Man Made Fibers - Other Textile Fibers
Fiber Blends
From Fiber to Yarn: Overview - Part I
From Fiber to Yarn: Overview - Part II
Melt-Spun Fibers

The Glossary of Terms and Fabrics and Timelines have been updated. The Glossary and Timelines will be updated in the future to incorporate more definitions and timeline events that we should be aware of in our art practice.

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Introduction
Chemical spinning produces filament fiber, filament yarn and filament tow. (Filament tow is made into a staple and processed by mechanical spinning – see previous post). It is a process in which a polymer solution is extruded through a spinneret, solidified in fiber form and the individual filaments are immediately brought together with or without a slight twist to make the yarn, which is then wound onto a bobbin. Thus filament fiber spinning and filament yarn spinning are parts of the same process.

Chemical spinning of a filament yarn.

Before the twentieth century the only continuous filament yarn was silk, an item of luxury. All utility fabrics were made with yarns containing staple fibers. Man-made continuous filament yarns made silk-like fabrics available for the mass market. Continuous filament yarns are classified into two groups: regular filament yarns (today’s post) and textured filament yarns (a future post).

Continuous filament fibers of PrimaLoft Synergy multi-denier insulation.
Image courtesy of PrimaLoft.


Regular Filament Yarns
When a new fiber is being developed, filament yarn production usually proceeds production of tow for staple. Filament yarns are more expensive in price per pound; however, the cost of making tow into staple and then spinning it into yarn by the mechanical spinning process usually makes the final cost approximately the same. The number of holes in the spinneret determines the number of filaments in the yarn.


Polyester tow waste.

The filament yarn is a finished product unless additional twisting or finishing is required in which case the yarn is sent to a throwing mill.

Throwing is a term that originally meant twisting and/or plying (doubling) of the filament. It now includes finishing and texturizing. Throwing process provides the weaver or knitter with the type of yarn needed for a particular fabric to be made – crepe or voile, for example. Throwsters work in two ways: they buy the raw yarn, process it and sell the process yarn; or they work on a commission basis in which the customer buys the raw yarn, and sends it to the throwster who processes to order, and returns it to the customer, charging for their services. The latter scheme is beneficial for the customer, since they can meet the seasonal demand and fashion changes without investing in specialized equipment.

Banana silk throwster – multi-colored.


Characteristics of Filament Yarns
Regular filament yarns are smooth and silk-like as they come from the spinneret. Their smooth nature gives them more luster than spun yarns, but the luster varies with the amount of delustering agent used in the spinning solution and the amount of twist in the yarn. Maximum luster is obtained by use of bright filaments, which are laid together with little or no twist. Crepe yarns, of very high twist, were developed as a means of reducing the luster of filaments. Filament yarns are generally used with either high twist or low twist.


High twist polyester yarn.

Low twist singles yarns and knit samples. These yarns and samples have been washed but not blocked.

Filament yarns have no protruding ends so they do not shed lint; they resist pilling and fabrics made from them shed soil. Filaments of a round cross-section pack well into compact yarns, which give little bulk, loft or cover to a fabric. Compactness is a disadvantage in some end-uses, where bulk and absorbency are necessary for comfort.

The strength of a filament yarn depends on the strength of the individual fibers and on the number of filaments in the yarn. Filament fiber strength is usually greater than that of staple fibers. For example,
(i) polyester filaments – 5 to 8 grams per denier tensile strength.
(ii) polyester staple – 3 to 5.5. grams per denier tensile strength.
Note: Denier is defined as mass in grams per 9000 meter of a filament.

The strength of each filament is fully utilized. In order to break the yarn, the filaments must be broken. Therefore, it is possible to make very sheer fabrics of fine filaments that have good tensile strength. Filaments yarns reach their maximum strength at about 3 turns per inch or per 2.5 cm, after which the strength either remains constant or decreases.

Fine filament yarns are soft and supple. However, they are not as resistant to abrasion as coarse filaments; so for durability, it may be desirable to have fewer, but coarser filaments in the yarn. Filament yarns are made with a denier (size) designed for a particular end use. For example,
(i) 15 denier for sheer hosiery.
(ii) 40 to 70 denier for tricot lingerie, blouses and shirts.
(iii) 140 to 520 denier for different types of apparel.
(iv) 520 to 840 denier for upholstery.
(v) 1040 denier for yarn for carpets.

Hoisery – is sheer but not durable, due to its small tensile strength. However, due its low tensile strength, it has a soft handle.

A comparison of spun yarns and filament yarns are given in the following table.

Comparison of spun yarns and filament yarns.


Reference:
[1] N. Hollen and J. Saddler, Textiles, 3rd Edition, MacMillan Company, London (1968).