1. Introduction

Sizing of yarns is very important in modern textile industries to improve the mechanical and processing properties of yarns so that they can be woven on high-performance looms. Conventional sizing agents include food-grade starch, which has been widely used due to their easy availability and effectiveness. However, consumption of these materials raises huge concerns regarding resource sustainability and economic feasibility considering the ever-growing global demand for food products.

Synthetic sizing agents, being homo- and copolymers, were introduced to surmount all these challenges. In such regards, synthetic agents have the advantage of sizing without the use of food-grade materials and show advantages regarding uniform film formation and high adhesion to fibers. They have a number of disadvantages. Synthetic polymers are expensive, often difficult to procure, and lack multifunctionality for fibers of varied chemical composition. Moreover, at the same time, they present some problems during the desizing process: high consumption of water, longer processing times, incomplete removal from fabric surfaces. The critical disadvantage refers to the tendency of yarns sized exclusively with synthetic polymers to stick together upon drying; this creates a lot of inefficiency during weaving and their use on high-speed machines.

Given these limitations, the search for novel yarn sizing methods becomes pressing to combine advantages of natural and synthetic agents. Among these, the development of water-soluble polymer-based sizing compositions, especially with the use of starch, polyvinyl alcohol, and hydrolyzed polyacrylonitrile, assumes importance in view of the potential for reduction of food starch consumption and improved yarn performance. In spite of such a possibility, scientific investigation into such hybrid compositions is scant, with only a few studies pointing toward preliminary understanding in their formulation and application [1].

This paper, therefore, seeks to fill this knowledge gap by formulating and providing a physicochemical justification for a new sizing composition in cotton yarn, incorporating PVA and HIPAN. The study aims to optimize formulation and processing parameters for minimal dependency on food-grade starch, maintaining improved elastic, structural, and mechanical properties of the sized yarn. The use of special-purpose textile auxiliary substances further improves the properties of the proposed composition through solving the problem of sticking and ensuring efficient yarn treatment on high-performance looms [2,43,44,45,46].

It is assumed that during the interaction at the molecular level between starch, PVA, and HIPAN polymer groups, some amide-CO-NH-, urea-NH-CO-NH-, carbamate-OCO-NH2, ester -OCO-, and other functional groups may form. These will enhance the elastic properties of the adhesive film, reducing its electronegativity, hence improving its mechanical properties.

Besides, the study pointed out that the drying process is of crucial importance for sizing cotton yarn. Among the key parameters - temperature, drying time, and warp movement speed - the optimal kinetics was established to dry the yarn treated with the proposed composition. Results are given in Table 1 and provide the comprehensive understanding of the drying process and its influence on weaving efficiency [4].

Thus, this work brings about the improvement of different sustainable and resource-efficient technologies in textile production because of both economic and ecological benefits by responding to challenges developed by both traditional and artificial sizing agents (Table 1).

Table 1. Kinetic parameters of the drying process of yarn sized with a composition based on starch, PVA and HIPAN at a ratio of 1:0.05:0.01, respectively

Based on the study of the kinetic parameters of the sizing process, the developed compositions determined the concentrations of the components included in the sizing composition, which is presented in Table 2. As can be seen from the table, the amount of the sizing polymer composition is 50 g / kg, against the starch-based sizing–70 g/kg, i.e. starch consumption is reduced by 25–30% [3].

Table 2. Optimal technological parameters for the preparation of sizing based on the developed composition

It was found that the drying rate is predetermined by the chemical nature of the preparation, the fiber composition of the yarn, and the time and temperature conditions of drying. The ability of yarn treated with various sizing preparations to lose moisture mainly depends on the type of composition. The relatively low ability to retain water molecules is explained by the presence of hydrophobic cycles in the PVA and HIPAN macromolecules [5,26,27,28,29,30,31,32,33].

It should be noted from the data obtained that the specific breaking load is one of the main physical and mechanical indicators of cotton yarn. The breaking load of yarn sized with the proposed composition is 13–15% higher than in the traditional case, with the same coefficient of variation.

Below are comparative results of cotton yarn sizing with a composition based on the developed composition with data on yarn sizing with starch under the conditions of the enterprise LLC “NAQSH OYDIN” (Table 3). As can be seen from Table 3, the concentration of the sizing, which has a significant impact on the cost of the sizing, fluctuates within 45–50 g/kg of the composition, against 70 g/kg of starch sizing, although the true adhesive remained at the same level. According to the results of the experiment, it was found that in the case of sizing cotton yarn with the developed sizing compositions, a significant reduction in starch is achieved, i.e. by 25–30%, which is in economic and environmental terms about the feasibility of using the developed composition [6].

Table 3. The physical and mechanical properties of yarn treated with sizing obtained under optimal preparation parameters

It has been established (Table 4) that yarn breakage depends on a number of factors: the method of its spinning, the chemical nature of the fiber composition of the yarn, the nature of PVA and HIPAN and their amount in the sizing agent. Processing yarn with this sizing agent during weaving allows reducing warp breakage by 35–40%, increasing productivity by 5–10% and reducing shedding by 20–25% compared to starch sizing agents [7].

Table 4. The average breakage and productivity rates in weaving

The results of the analysis of the technological indicators of the process of sizing yarn with the developed polymer compositions (Table 4) show that as a result of sizing a strong base is obtained with minimal consumption of sizing and TAS [12].

2. Conclusions

Thus, it is shown that the viscosity of aqueous solutions depending on the concentration, temperature and pH of the solution of the sizing composition is described by a first–order equation. It is approximately 2–3 times lower than sizing preparations from starch sizing. The use of preparations from the developed composition of the sizing composition allows increasing the speed and degree of impregnation of the yarn in the sizing process, which increases the mechanical fixation of the adhesive film on the fiber and has a positive effect on weaving [8].

It has been found that cotton yarn treated with polymer compositions can be processed on various types of weaving machines, while providing a 35–40% reduction in breakage and a 5–10% increase in machine productivity compared to yarn sized with starch sizing [9,34,35,36,37,38,39,40,41,42].

At the present stage of development of textile industry, pigments and active dyes are mainly used in the production of printed fabrics. The share of these dyes in comparison with other classes of dyes reaches up to 80%. Despite this, printing with the above–mentioned dyes, which have advantages and difficulties from the technological point of view, remains an urgent task. Justification of the choice of thickener largely depends on their rheological and printing properties, as well as the quality of the coloring of the printed fabric. It should be noted that in textile enterprises, starch and its derivatives are mainly used as cheap thickeners when printing with cold dyes. However, the use of starch as a thickener has a number of disadvantages, namely, it enters into chemical interaction with active dyes, and this in turn leads to a significant overconsumption of starch and dye, and is also poorly washed off the surface of the fabric [10].

The use of modified starch as a thickener for printing inks, which forms a strong film on the surface of the fabric, leads to an increase in its rigidity, which is not typical for printing with active dyes. In this regard, it is proposed to use a thickening polymer composition that forms films with increased elasticity [11,13,14,15].

Table 5. Performance of fabrics printed with reactive dyes

In addition, the analysis of the data in Table 6 shows that cotton fabric printed with active dyes based on starch thickener does not sufficiently ensure the color fastness to dry friction (2 points) and imparts increased rigidity to the printed fabric (6.7 times). In order to solve this problem, a sericin solution was introduced into the composition of the recommended printing composition in addition to modified starch and CMC, while the rigidity index (2.7–6.7 times) practically decreases to the level of alginate thickener (1.8 times), (changes in the range of 0.2–1.1) [16,17,18,19,20].

Table 6. The coloristic characteristics of cotton fabric printed with active dyes thickened with compositions

The analysis of the obtained results (Table 6) shows the importance of maintaining the quantitative ratio in the starch system within 5.0–5.5%, Na–CMC–0.2–0.3% and sericin–0.15–0.2%. This reduces the stiffness of the fabric, produces bright and durable colors, and eliminates any pronounced spreading of paint beyond the outline of the pattern with full fabric printing. The degree of fixation of active dyes (after washing the printed samples) is at a high level (95–96%).