other equipment.

TRAVEL NEWS

INTRODUCTION

Yarns made from wool/polyester blends are well suited for a variety of woven and knitted textile products. Desirable characteristics of products made from these blends are comfort, strength, and wrinkle resistance. Market penetration of this blend is limited, however, by the fact that the yarns are typically spun on long staple spinning systems to accommodate the wool fibers. The global capacity of these spinning systems is small and the processing costs are relatively high. If yarn spinning could be accomplished on the short staple (cotton) spinning system, then the use of this blend could be increased.

There is no fundamental reason why the long staple spinning system must be used for wool/polyester blends. Polyester is commonly cut to lengths suitable for the cotton spinning system. Wool can be provided in these lengths by shearing the sheep twice a year instead of only once. Certainly this is feasible in sheep production areas with mild winter climates, as in the southern United States, Mexico, Australia, and South Africa. The term used for this fiber is “short-shorn wool,” or SSW.

The feasibility of spinning wool blends on the ring spinning system has been demonstrated [1, 2, 3]. However, if the spinning could be successfully done on the rotor spinning system, then the manufacturing costs would be much lower and the pricing point needed for profitable production would enable greater market penetration. Past experience at the International Textile Center has shown that spinning this blend on the rotor spinning system is often not feasible [4, 5]. Nevertheless, we thought that the new Rieter R 20 spinning machine had potential for doing it, because the trash ejection channels associated with the combing rollers can be manipulated to prevent the loss of wool fibers before they pass into the rotor chamber. Even if a consistent rotor spinning process is achieved, the ultimate challenge is to produce a yarn with sufficient strength to substitute for those produced on traditional, long staple systems. This article provides a short report on preliminary results obtained in producing 8 Ne rotor yarns.

PROCEDURES

In tests to select appropriate machinery settings, two different polyester fibers were utilized: Wellman Type 315 and Celanese Type 221. The fineness of both was

2.25 denier and the staple length of both was 38.1mm. Texas short-shorn wool of U.S. grade 64 was used throughout the study. The mean length of the wool was 46.7mm, with a coefficient of variation of 41.4%. Intimate blends of the fibers were used throughout; in evaluating the machinery settings, the blend was 50:50 SSW/poly.

Machinery Settings

Exhibit 1 outlines the machinery and some of the major settings used to process the fibers. All stages up to the spinning were handled in a typical fashion for this blend of fibers. It should be emphasized, however, that a well adjusted, cotton-system opening line operating on the short staple wool and polyester provides excellent cleaning and blending—both of which are critical for successful rotor spinning.

At the spinning machine numerous modifications were tested. The most important one was to partially close off the trash ejection channels below the combing rollers of the R 20. This proved to be necessary to facilitate the flow of wool fibers into the rotor. Following preliminary study of key machine variables, the major tests made are discussed below. (Note: Unless otherwise indicated, tests were done using the 50:50 blend containing Celanese T221 polyester.)

TEXTILE TOPICS

Published quarterly Texas Tech University a research bulletin on fiber and

International Textile Center textile industries.

P.O. Box 45019 Fall 1999 - Issue 4 Lubbock, TX 79409-5019

RESULTS

The focus is on the six yarns identified in Exhibit 6. Major results of the yarn testing are given below.

• Yarn strength results are summarized in Exhibit 7. For the 1.5 denier polyester fibers, the Dupont fibers produced a somewhat stronger yarn than did the Wellman fibers for the 50:50 blend (yarn #1 vs. yarn #2), but not for the 60:40 blend (#3 vs. #4). For the 1.0 vs. 1.5 denier Wellman fibers, the strength is greatly increased for the 50:50 blend (#5 vs. #1), but not for the 60:40 blend (#6 vs. #2). Clearly, the loss in strength occurs quickly when wool is increased beyond the 50:50 blend level (#1, #2 & #5 vs. #3, #4 & #6). On the average, a 20% loss in yarn strength resulted from the 10% increase

in wool fibers. made from the long staple system was approximately

• Yarn Imperfection values are summarized in $5.00 /pound; for this rotor-spun yarn, we think a Exhibit 8. It reveals no significant differences in profitable pricing point would be approximately half imperfections across the six yarns. All of the that amount. imperfection values are at good levels; furthermore, the visual appearance of these yarns was quite It seems that yarn and fabric appearance would be good. adequate with this process—if acceptable yarn strength

and fabric durability can be achieved. Given the CONCLUSION observed sensitivity of yarn strength to the wool This study indicates that there is potential for making content, further testing should explore the use of lower

high-quality yarns and fabrics with SSW/poly blends on percentages of wool in the blend. Since 65:35 poly/ the rotor spinning system. If so, the yarn manufacturing wool blends have exhibited large-scale popularity in the costs would be greatly reduced from those incurred clothing market, producing a comparable yarn and with long staple spinning systems. At the time this fabric using a 65:35 poly/SSW blend should be evalustudy was done, the pricing point for wool/poly yarns ated.

EXHIBIT 1: OUTLINE OF MECHANICAL PROCESS FOR BLENDS OF SHORT SHORN WOOL AND POLYESTER

R20/10 Beater Speed = 850 rpm (Fitted with synthetic pan)

Production Rate = 60 lb/hr Sliver Weight = 60 gr/yd

Delivery speed = 1,320 ft/min Sliver weight = 60 gr/yd

Delivery speed = 1,320 ft/min Sliver weight = 65 gr/yd

fall 1999

EXHIBIT 2: EFFECTS OF COMBING ROLLERS ON YARN PROPERTIES

Roller Type	CSP	Tenacity	Elongation	Mass CV	Thin Places	Thick Places	Neps	Hairiness
	(Ne > lb)	(cN/tex)	(%)	(%)	(no/ky)	(no/ky)	(no/ky)
OS21DN	1822	11.03	21.15	15.30	29	103	6	7.61
OS21/6DN Pin Roller	1757 1658	10.88 10.27	20.66 18.12	15.35 15.00	29 18	111 88	6 7	7.51 7.72

EXHIBIT 3: EFFECTS OF COMBING ROLLER SPEED ON YARN PROPERTIES

Roller Speed	CSP	Tenacity	Elongation	Mass CV	Thin Places	Thick Places	Neps	Hairiness
(rpm)	(Ne > lb)	(cN/tex)	(%)	(%)	(no/ky)	(no/ky)	(no/ky)
6,500 7,000 7,500	1864 1811 1822	11.08 10.88 11.03	21.83 21.20 21.15	15.43 15.30 15.30	30 27 29	106 98 103	12 8 6	7.60 7.65 7.61

EXHIBIT 4: EFFECTS OF ROTOR TYPE AND SPEED ON YARN PROPERTIES

Rotor CSP Tenacity Elongation Mass CV Thin Places Thick Neps Hairiness Type* Places

(Ne > lb) (cN/tex) (%) (%) (no/ky) (no/ky) (no/ky)

70,000 rpm

35mm SB 1823 11.03 21.15 15.30 29 103 6 7.61 40mm SE 1755 10.63 18.79 15.68 46 139 9 9.16 40mm SB 1771 10.54 19.43 15.58 32 142 13 8.38

61,110 rpm

40mm SE 1856 11.23 21.14 14.68 15 70 6 8.47 40mm SB 1842 11.26 21.42 14.50 11 70 6 8.17

* S denotes the type of rotor groove and the second letter denotes the material or coating for the rotor; B stands for boron and E identifies an experimental rotor.

EXHIBIT 5: EFFECTS OF TWIST ON YARN PROPERTIES

Twist Multiplier	CSP	Tenacity	Elongation	Mass CV	Thin Places	Thick Places	Neps	Hairiness
	(Ne > lb)	(cN/tex)	(%)	(%)	(no/ky)	(no/ky)	(no/ky)
4.2 4.4 4.6 4.8	1922 1955 1989 2025	11.81 11.94 12.02 11.95	14.91 15.09 15.43 15.54	15.12 14.85 14.80 14.66	18 17 13 10	74 76 62 66	7 8 6 8	7.67 7.56 7.46 7.45

EXHIBIT 6. VARIABLES INVOLVED IN SPINNING DIFFERENT YARNS

Yarn ID	% Wool in Blend	Polyester Source	Polyester Denier
#1	50	Wellman	1.5
#2	50	Dupont	1.5
#3	60	Wellman	1.5
#4	60	Dupont	1.5
#5	50	Wellman	1.0
#6	60	Wellman	1.0

EXHIBIT 7. YARN STRENGTH RESULTS FOR DIFFERENT YARNS

Yarn ID	CSP	Tenacity	Elongation
	(Ne > lb)	(cN/tex)	(%)
#1 #2 #3 #4 #5 #6	1839 2017 156915912037 1555	10.30 11.48 9.46 9.66 12.38 9.63	19.17 23.14 18.55 21.80 14.37 13.49

fall 1999

EXHIBIT 8. YARN IMPERFECTION VALUES FOR DIFFERENT YARNS

Yarn ID	MassCV	Thin Places	Thick Places	Neps	Hairiness
	(%)	(no/ky)	(no/ky)	(no/ky)
#1 #2 #3 #4 #5 #6	14.23 14.01 14.62 14.41 14.18 14.71	7 4 8 11 4 11	60 51 80 62 62 82	5 6 9 11 11 11	7.50 7.12 7.80 7.62 7.11 7.67

REFERENCES	4.	Price, J. B., “The Development of Woven and
1. Harry, A. A., and G. A. Robinson, “Processing of		Knitted Fabrics from Blends of Texas Cotton,
Wool and Wool-Rich Blends on the Short Staple		Wool and Mohair,” Annual Progress Report to the Texas
System. I. A Modified System for Wools of		Food and Fibers Commission for the Period September 1,
Average 40mm length but with a Non-square Fiber		1989 – August 31, 1990, pp. 251-292.
Length Distribution,” CSIRO Rep. No. G31, 1977.	5.	Zhu Reiyao and William D. Cole, “Study of Short
2. Louis, G. L. and C. E. Pardo, “SRRC Natural Fiber		Staple Processing of Wool/Cotton Blends on
Blend Research,” Textile Research Journal, 50, 130		Rotor Spinning System,” Textile Topics, International
136, 1980.		Textile Center, Spring 1997.
3. Lupton, C. J., “Wool Processing on the Cotton
System: A Comparison Between Cut-Top wool and
Six-Month Shorn Wool in a Blend with Polyester,”
Textile Research Journal, 50-2, 119-129, 1980.