George F. Ruppenicker

Improved Method of Producing a Cotton Covered/Polyester Staple-Core Yarn on a Ring Spinning Frame

A new, better method of producing cotton covered/polyester staple-core yarn on a modified ring spinning frame is described. The method uses the concept of twisting a “sandwich” formed by two drafted strands of cotton (rovings) on the outside and a drafted strand of polyester on the inside, thus using a total of three rovings. The earlier method used only one cotton roving and one polyester roving [10]. The new method is simple and easily adaptable to the existing spinning frames; piecing of broken ends is also easy. A 67/33 cotton/high tenacity polyester staple-core yarn produced by the new spinning system is evaluated. The core of the yarn is almost totally covered with a firm sheath of cotton, giving the an appearance of a 100% cotton spun yarn. Compared with conventional yarns of 100% cotton and 67/33 cotton/polyester intimate blends, the core yarn is significantly stronger than the equivalent 100% cotton yarn and the intimate blend yarn of regular tenacity polyester. These yarns may be useful where a co-axial segregation of different fibrous materials is important or critical. The new staple-core spinning technology can be applied to produce yarns from a variety of core and sheath materials, such as Kevlar, PBI, Nomex, cotton, and wool, among others.

Comparison of Filament-Core Spun Yarns Produced by New and Conventional Methods

In recent years, we have been reporting our research on composite yarns of mostly cotton content produced on a modified ring spinning system. Recently, we reported an improved method of producing an all staple-core spun yarn, and we have applied the same method to filament-core spinning, obtaining a yarn of greatly improved quality. The new filament-core yarn has almost total core coverage, does not strip, and is about 10% stronger (probably due to its improved yarn structure) than a conventional filament-core yarn. This paper briefly describes the new and conventional core spinning methods and evaluates nylon filament-core/cotton-wrap yarns produced with them. There is also a comparison of the cover factor, strip resistance, and microscopic cross sections of a few other core yarns (with Kevlar, fiberglass, and polyester cores). A significant improvement in the cover factor of the new yarn suggests that it may be very useful for sewing threads; ropes; twines; cables; special military, industrial, and surgical fabrics; and other textiles in which the high strength, durability, and a 100% cotton surface (for ease of finishing or coating) are important.

Comparison of Cotton/Polyester Core and Staple Blend Yarns and Fabrics:

Cotton wrapped polyester core yams produced on a modified ring spinning frame were compared with yams spun from staple fiber blends. The yams contained ap proximately 70% cotton and 30% polyester. Yarns and fabrics made from both regular and high tenaeity polyesters were evaluated. Fabrics produced from the core yams were stronger and more durable than those of the staple blends, and they maintained their superiority in these properties through wet processing and resin .finishing. Other advantages of the core-yam fabrics included better cover and abrasion resistance.

A Unique Polyester Staple-Core / Cotton-Wrap Yarn Made on a Tandem Spinning System

A unique, all-staple, core/wrap composite yarn of relatively fine size and low core content has been developed using the air-jet spinning and friction spinning technologies in tandem. First, a fine, high tenacity polyester staple yarn of 10-tex is spun on a Murata air-jet spinner, and this yarn is then used as the core material on a Dref-3 friction spinner. The air-jet yarn is covered with a wrap or sheath of 100% cotton fibers, producing a 30-tex, 33/67 polyester/cotton, composite yarn with a nearly 100% cotton surface. We have tested the yarn for its physical and mechanical properties, including core coverage factor and strip resistance, and compared it with the equivalent size polyester staple-core/cotton-wrap yarns produced by the USDA-patented ring spinning system. Because of the relatively fine size and low core percentage of the yarn, we were unable to produce a satisfactory comparable yarn on the Dref-3 spinner alone. The new air-jet/friction spun composite yarn can be knitted and woven without encountering stripping or other problems. This preliminary feasibility study has suc cessfully led to a unique integrated tandem spinning process that continuously and uninteruptedly produces an all-staple composite yam. The process will be reported on shortly.

Comparison of Fabrics Made with Cotton Covered Polyester Staple-Core Yarn and 100% Cotton Yarn

Cotton covered/polyester staple-core yams [6, 8], recently developed at the Southern Regional Research Center, and conventional 100% cotton yarns of equivalent size were woven and knitted into various fabrics for evaluation. The woven fabrics were tested for abrasion resistance and tear and tensile strengths. The knitted fabrics were tested for bursting strength, air permeability, pilling resistance, dimensional stability, and DP rating (after a light application of DP finish on the heat set fabric). The staple- core yams, which were only modestly stronger than equivalent 100% cotton yams, produced fabrics remarkably improved in all the important properties when compared to the fabrics made with conventional 100% cotton yams. Fabrics from staple-core yams should therefore be useful where strength, weight, durability, abrasion resistance, dimensional stability, easy care, and comfort are desirable or critical.

New Technique to Produce a Cotton/Polyester Blend Yarn with Improved Strength

This paper describes a newly developed, relatively simple but effective technique of producing a novel pseudo-composite cotton-rich staple blend yarn with improved tensile properties. The spacing between cotton and polyester rovings drafted simultaneously on a ring-spinning frame affects yarn structure, resulting in significantly stronger yarns than those produced by drafting the same two rovings together. The new composite or combination yarns may be useful in developing relatively stronger cotton-rich materials suitable for a variety of finishes and end uses.

Effects of Processing Variables on the Properties of Cotton Knitting Yarns

The effects of carding rate. total spinning draft, spindle speed, and other production variables on the strength, uni formity, and lint-shedding tendencies of ring-spun cotton knitting yarns were determined. The results showed that higher carding rates improved fiber orientation and produced stronger, more uniform yarns; however, neps in the yarn were increased. Increasing total spinning draft also produced stronger, more uniform yarns. Lower spindle speeds resulted in slightly stronger, more uniform yarns with fewer neps and other imperfections. Optimum conditions for minimum lint shedding during knitting were obtained with lower carding rates and higher total spinning drafts and spindley speeds. Other processing variables that favored reduced lint shedding were combing using double-creded roving, and increasing yarn twist.

Factors Affecting the Lint Shedding of Cotton Knitting Yams

The effects of fiber properties, yarn structure, knitting conditions, and yarn treatments on the lint-shedding tendencies of ring-span cotton knitting yarns were determined. Lint shedding of ring-spun and open-end spun yarns were compared. Cotton-polyester blends were also evaluated. Lint shedding increased as fiher length decreased. Increasing yarn twist produced almost a linear decrease in lint shedding. Finer yarns shed more lint than coarser yarns. Knitting conditions favoring reduced lint shedding were slower speeds, lower yarn and fabric tensions, and longer stitch lengths. Lint shedding was reduced substantially by sizing and waxing the yarns. Open-end-spun yarns shed less than carded ring-spun yarns but more than combed ring-spun yarns. Blending polyester with cotton reduced lint shedding in proportion to the amount of polyester added.

Cotton Blend Fabrics from Polyester Core Yarns

Core spun yarns with a filament core and a cotton wrap were prepared and made into fabrics. The properties of these yarns and fabrics in comparison with all-cotton and intimate staple blend controls were investigated. This study included the dyeing of these fabrics and finishing for smooth drying and flame retardancy.

Cotton Covered Nylon-Core Yarns and Greige Fabrics

Physical and mechanical properties of some specific cotton-rich, high tenacity, nylon- core yams and greige fabrics developed for military protective clothing are described. The core yams were produced on a modified ring spinning frame, and the fabrics were woven on a conventional dobby loom. The core yams and the fabrics developed from them contained approximately 70% cotton as cover and 30% high tenacity nylon filament as core. The core yams were about 25% stronger than comparable 70/30 cotton/nylon staple intimate blend or all-cotton yams, and the developmental greige fabrics were over 30% stronger. The developmental fabrics, after special finishing, may provide adequate flame retardancy as well as high strength retention. Properties of the finished fabrics will be reported separately.