CONTROL OF YARN TENSION DURING COMBINED SPINNING OF COTTON-MINTVAL MIXED YARNS

ABSTRACT

This study investigates the influence of yarn twisting and combination on mechanical and physical properties such as strength, elongation, and friction resistance. Cotton yarns were combined with water-soluble “Mintval” chemical yarn produced by “Kuraray Trading Co. LTD” (Japan) to develop innovative composite yarns. Owing to its solubility and thermal sensitivity, “Mintval” completely dissolves during finishing, enhancing the softness and surface quality of fabrics. Experiments using the USTER TENSOJET-4 at 400–550 twists per meter revealed that yarns twisted at 550 t/m achieved the highest breaking force (566,8 sN) and tenacity (24,47 cN/tex), fully meeting textile production standards.

АННОТАЦИЯ

В данном исследовании рассматривается влияние скручивания и комбинирования нитей на их механические и физические свойства, такие как прочность, удлинение и устойчивость к трению. Хлопчатобумажные нити были объединены с водорастворимой химической нитью марки “Mintval”, произведённой компанией “Kuraray Trading Co. LTD” (Япония), для получения инновационных композитных нитей. Благодаря своей растворимости и термочувствительности, нить “Mintval” полностью растворяется в процессе отделки, улучшая мягкость и гладкость поверхности тканей. Экспериментальные исследования, проведённые на оборудовании USTER TENSOJET-4 при уровнях скручивания от 400 до 550 витков на метр, показали, что нити, скрученные при 550 витках/м, обладают наивысшей разрывной силой (566,8 сН) и прочностью (24,47 сН/текс), полностью соответствуя требованиям текстильного производства.

Keywords: Mintval yarn, twisted yarn, water-soluble yarn, cotton yarn, twist level, yarn strength.

Ключевые слова: Минтовальная пряжа, скрученная нить, водорастворимая нить, хлопковая нить, степень скручивания, прочность нити.

Introduction. The following positive indicators can be achieved when twisting individual threads together:

• increasing the breaking load, smoothness, bending, elasticity, resistance to friction and bending, rigidity and balance of the thread;
• to obtain twisted polished shaped threads;
• when twisting threads of different linear densities, a crepe-colored shiny thread is obtained, from which a shiny fabric is obtained;
• when twisting threads of different colors, to obtain a colorful shimmering thread (this luster cannot be achieved by dyeing);
• to increase the number of types of twisted yarns with predetermined properties using chemical fiber yarns;
• additional twisting of chemical fiber threads, etc.

As we know, when spinning yarn, it is twisted with right (Z direction) twists. If two or three single threads need to be twisted together for the first time, then the threads are twisted in the right (Z) direction. If the twisted yarn needs to be twisted twice, it is twisted with twists in the left (S) direction. In this case, the twisted yarn has a structure (ZZS). Sometimes, twisted yarn with a (ZSZ) structure is also possible. The direction of thread twists is shown in Figure 1.

Figure 1. Direction of thread twists

The strength coefficient K depends on the twisting of the yarn, the direction of twisting, and the yarn thickness, and is around 1,2-2,2.

The effective influence of the degree of twisting on the strength of twisted yarn is characterized by the coefficient of utilization of fiber strength in yarn strength:

 coefficient of fiber strength utilization;

 relative strength of twisted yarn and fiber, g;

 relative strength of twisted yarn and fiber, g.

The balancing property of twisted yarn. If the twisted yarn is taut and then released without forming loops, such yarn acquires the property of being balanced. Single threads do not possess this property.

Chemical yarn of the “Mintval” brand is a complete chemical polymer with properties of thermal and hot-water solubility. The chemical yarn “Mintval” is water-soluble, and in the preparation process, the Japanese company “Kuraray Trading Co. LTD”, made from a water-soluble chemical polymer of the “Mintval” brand.

Characteristics of the “Mintval” chemical yarn: the “Mintval” chemical yarn consists of a compound of polyvinyl alcohol and ethylene.

 Since the composition of the “Mintval” chemical yarn is the same type of polymer, it can be easily spun together with natural fibers and used in wrapping.

Figure 2. Chemical composition of the “Mintval” brand chemical yarn

The polymer properties of the “Mintval” chemical yarn are better than that of other PVA yarns and have the property of rapid dissolution. Since the chemical yarn “Mintval” is thinner than the existing PVA yarn, it is much easier to dispose of and completely washes away from the fabric during the fabric finishing process.

By winding “Mintval” chemical yarn together with other yarns and preparing low-twist yarns, it can be used to make pile fabrics, suit fabrics (wool, cashmere), dress and knit fabrics, and various fabrics used in industry. After the melting process of “Mintval” yarn, a new appearance is formed in the fabrics formed from it. Processes that can be created using “Mintval” chemical thread.

“Mintval” can retain the fineness of the second yarn wrapped together with the chemical yarn. The “Mintval” chemical yarn ensures the strength of the yarn attached to it.

In the process of dyeing and finishing the fabric, the threads in the fabric become soft due to the release of the “Mintval” chemical thread. The “Mintval” chemical yarn can retain 100% of the natural elongation of the yarn added to it.

When wound together with cotton yarn and “Mintval” chemical yarn, the properties of the cotton yarn do not change after the dissolution of the “Mintval” chemical yarn during the finishing process. Dissolution properties of “Mintval” chemical yarn – “Mintval” chemical yarn completely dissolves in water at almost 80°C and 80°C and completely escapes from the fabric.

Physical properties – “Mintval” chemical yarn has such properties as fineness, abrasion resistance, and strength.

Materials and methods.  Installed at the “Art Soft Tex” textile enterprise on a TW2-D winding machine manufactured by the Swiss company “SSM”, Japanese “Kuraray Trading Co.” was produced with 100% cotton yarn (Ne 16/1), (Nm 27/1), 37.03 tex, spun by the ring spinning method at the “Navoi teks” enterprise (Nm 243.9), (Ne 144.1), 4.1 tex “Mintval” brand water-soluble chemical yarn was used to produce yarn with a new composition.

Figure 3. Microscopic view of the recommended 37.03 tex 100% cotton yarn with the addition of “Mintval” brand water-soluble chemical yarn

At the “Pop Fen” LLC enterprise, the average number of twists of single cotton yarn spun 704 times in the direction of T=37.03 tex (Z) with a water-soluble chemical yarn “Mintval” of T=4.1 tex in the direction of 550 twists/meter (S) using the “Yarn twist meter” device was 789 twists/meter.

Figure 4. Diagram of sharp difference of twists located at 1 meter

In this diagram, it can be seen that the arrangement of twists per 1 meter in yarns twisted at 400, 450, and 500 twists/meter differs sharply. The arrangement of twists per 1 meter of yarn with 550 twists/meter is almost uniform and evenly distributed.

Yarn tensile strength is one of the most important indicators of its quality. Yarn tensile strength refers to its resistance to external forces. The term breaking force is used instead of the term strength.

The minimum force required to break a string of a certain length is called the breaking force and is measured in Newtons (N) or KGS.

The “USTER TENSOJET-4” device was used to determine the strength of the yarn. Absolute and relative values are used to express yarn strength.

The breaking force of one or more threads is an absolute value, and the breaking length per kilometer is a relative value.

Relative quantities include the relative strength of the yarn (SI), tex, or breaking length (sm), and quality.

Relative strength (relative elongation force) is numerically equal to the strength of yarn reduced to linear density (Tex) (R, cN).

The breaking load is denoted by R, and the excess force in it determines the resistance to breaking, as it is determined by weighing.

The method and number of tests for each sample are determined by GOST 6611.0-73 and GOST 6611.4-74.

Results and discussions. The strength of the twisted yarn exceeds the sum of the strengths of all individual yarns involved in twisting. The reason for this is that during the twisting process, the pressure between fibers and individual threads increases, the overall friction and breaking resistance increase, therefore, the thread becomes strong.

The strength of the twisted yarn is determined by the following formula:

R_str = R_s·m·K

R_tw.str – twisted yarn strength, N; 

R_s – single thread strength, N;

m – number of additions;

K – strength coefficient.

 At the enterprise “Art Soft Holding” LLC, water-soluble chemical yarn “Mintval” of T=4.1 tex was twisted in the direction of twist (S) with a single cotton yarn twisted 704 times in the direction of twist T=37.03 tex (Z) in 4 samples of different values, i.e., the strength of yarns twisted in the direction of 400, 450, 500 and 550 twists/meter (S), and the breaking strength, elongation at break, and relative strength of each sample of yarn were determined on the “USTER TENSOJET-4” device in the laboratory of the enterprise “Namangan Tukimachi Holding” LLC, and the following results were obtained.

Table 1.

Mechanical indicators of yarn twisted with “Mintval” yarn

Figure 5. Breaking load diagram of yarn twisted with “Mintval” yarn

From the diagram in Figure 5, it can be seen that the breaking load of yarn twisted at 550 twists/meter is on average 38.5 cN higher than that of yarn twisted at 400, 450 and 500 twists/meter, and fully meets the requirements for the production of textile products. This can be explained by the high number of twists and the high density of the fibers wrapped around the “Mintval” yarn.

Conclusion. Based on the experimental results, combining single yarns with “Mintval” water-soluble chemical yarn significantly improves their physical and mechanical properties. The yarn sample twisted at 550 turns per meter showed the highest breaking strength (566,8 sN) and tenacity (24,47 cN/tex). Due to the solubility and heat sensitivity of “Mintval” yarn, it easily separates from the fabric during finishing, enhancing the softness and smoothness of the final textiles. Such yarns can be effectively used in the production of suit, shirting, and knit fabrics. Overall, the use of “Mintval” chemical yarn is a promising direction for improving yarn manufacturing technology and developing new types of functional textiles.

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