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Section 5. Chemistry
https ://doi.org/10.29013/AJT-19-9.10-44-48
Amonova H.,
Candidate of Technical Sciences, Associate Professor, Department of Medical Chemistry, Bukhara State Medical Institute Shukurov I.,
Associate Professor, Department of Medical Chemistry,
Bukhara State Medical Institute Majidov A.,
Senior lecturer, Department of Medical Chemistry, Bukhara State Medical Institute E-mail: [email protected]
DRESSING MATERIAL FOR THE POLYMER COMPOSITION BASED ON SYNTHETIC POLYMERS
Abstract. It was found that the presence of a dressing composition based on rice starch, PAA and sericin has a positive effect on the process of gelatinization of starch sodium metasilicate and increases the viscosity of the system.
Keywords: Modification of polymers, carbamine groups, sulfates and vinyl polymers, dressing with hydroxyethylated starch.
Purpose. Development of technology for ob- Relevance of the work. n modern conditions of
taining a polymer composition based on starch and formation of market relations improvement of qual-
sericite, the study of their influence on the properties ity and competitiveness of production is one of the of dressing compositions and the main indicators of key tasks in the textile industry solved by creation
dressing cotton yarn. of the effective resource-saving technologies allow-
Material and methods. IK - spectroscopy, bacte- ing to reduce considerably consumption of a food
rioscopy, sorption, coloristic and other physical and product of starch and expensive import, imported
chemical methods of analysis and research according chemical materials.
to the methods set forth in the relevant GOST. Throughout the history of textile production,
Results. The use of the polymer composition starch has played a leading role as the basis of dressing
allows to simultaneously reduce the starch content compositions due to its cheapness, availability and
in the dressing compositions and improve the most adjusted production. Currently, despite the availabil-
important physical and mechanical characteristics ity of a number of synthetic products for dressing,
of the coated bases. the situation has not changed fundamentally. The
proportion of starch dressing material for compositions up to about 75%. In the context of the economic crisis, a special place is occupied by the issue of creating polymer composite materials and the search for new types of dressing compositions that reduce the consumption of starch and meet the technological requirements on the world market.
Currently, the traditional starch-based dressing components used have a number of disadvantages, so only modified forms of starch are used abroad. Synthetic dressing preparations are devoid of these disadvantages. However, due to the unreliability of the raw material base and the high cost at present, synthetic dressing agents can not completely replace starch products in the dressing of cotton base.
In this regard, the problem of developing a technology for obtaining a polymer composition based on starch and sericin, providing an improvement in its adhesive ability, increasing the elasticity of the formed films and, accordingly, reducing the consumption of dressing is of great scientific, theoretical and practical interest.
Object and subject of research. The object of the study were starch, sericin-waste silk mills, polyacryl-amide (PAA).
The subject of the study was to reduce the resource intensity of weaving production by obtaining high-efficiency dressing polymer compositions based on local raw materials and the involvement of waste silk mills, providing good quality dressing yarn.
The hypothesis of the study is that the composition containing starch and sericin should have an increased efficiency of dressing compared to existing dressing agents.
In the process of dressing can significantly change the physical and mechanical properties of the main yarn, which affects the breakage of the threads on the loom. To reduce breakage in weaving production it is necessary to conduct the dressing process qualitatively.
The essence of the traditional process of dressing is that the main threads from the warping shafts at a given tension is impregnated with a solution of dress-
ing, excess amount of dressing is removed from the threads when pressed in the pressing shafts, drying of the coated threads is carried out in a drying apparatus to a certain humidity, separation of the glued threads and send them to the loom.
In this case, the dressing must meet the following requirements [1-3]:
- be sufficiently adhesive and have a certain viscosity to cover the surface of the main yarn and partially penetrate deep into the thread;
- create an elastic sheath on the threads, resistant to abrasion, does not violate the flexibility of the thread and does not make the yarn brittle and stiff, as well as not to fall off the yarn, both in the process of dressing and when processing the yarn on the loom;
- have a good affinity for fiber, do not destroy the yarn and do not change the color of the thread when dressing colored bases, easy to remove and do not affect the color and finish of fabrics, do not change their properties during use and storage;
- not to spoil the heddle and the reed on the loom, not to promote adhesion of the yarns to the drying drums;
- easy to remove from the surface of the yarn when loosening;
- be cheap enough.
The quality of the dressing is determined by a complex of physical and chemical properties, such as: concentration, viscosity, degree and uniformity of dispersion of the adhesive material, wetting ability, adhesion and cohesion properties.
Substances included in the composition of the dressing, according to its functional purpose can be divided into the following groups: adhesives, splitters, softeners, hygroscopic substances, antiseptics and water.
The main adhesive when dressing cotton threads is a natural polymer-starch (potato, maize, corn, rice). To break down the starch grains into smaller particles that penetrate deep into the thread, splitters are used: sodium hydroxide, sulfuric acid and other acids.
Due to the fact that the textile industry consumes for production needs a large amount of valuable food product - starch, the question of partial or complete replacement of its chemical materials is very relevant. With the development of chemistry and technology of polymers appeared chemical water-soluble adhesives, which in their properties are not inferior to starch products. These are mainly modified natural and synthetic polymers-simple and some cellulose esters, polyvinyl alcohol, poly-acrylamide, etc.
The analysis of scientific data shows that in the world practice as dressing agents, the following synthetic polymer compounds are used [4]:
- carbon-chain polymers and their derivatives;
- polyoxy (hydroxy) compounds;
- polyamides;
- various copolymers containing in the chain, along with functional groups such as-Coon,-COOR,- Oh, - NH2, etc., aromatic radicals and un-saturated bonds.
There are foreign patents describing dressing compositions based on synthetic high molecular weight compounds, in particular, styrene and maleic acid copolymers, polyvinyl alcohol and its copolymers, polyvinylpyrrolidone, acrylic (methacrylic) polymers and copolymers based on them, as well as many others. Note that they were used instead of carboxymethylcellulose, starch, gelatin, because these synthetic dressing compositions had negative properties-a tendency to flaking [5].
Currently, polyacrylamide is successfully used for dressing the bases. When dressing cotton yarn, it has long been used as a partial substitute for food. The dressing was usually introduced 70% starch and only 30% polyacrylamide, which provided good properties of the yarn. In the future, thanks to the conducted developments, numerous compositions based on polyacrylamide, both 8% and 6%, products of its alkaline or oxidative degradation and other copolymers were used [6]. The use of polyacrylamide made it possible to completely eliminate the use of starch.
For dressing, 8-10% polyacrylamide (PAA) or a mixture of it with starch products, gelatin or other adhesives are used. Note that PAA shows sufficient resistance to temperatures up to 400-420°K. Due to the absence of ionogenic groups, when the pH changes from 1 to 10, its viscosity does not change significantly, and this is very important for the dressing process.
In the process of alkaline treatment, part of the amide groups passes into carboxyl and intermolecular bonds of the polymer chains of PAA significantly weaken, thereby increasing solubility and reducing viscosity. The products of alkaline treatment of PAA can be represented as a copolymer of acrylamide, acrylic acid and its sodium salt. It is used for dressing cotton and staple yarn.
The viscosity of the dressing on the basis of PAA can be reduced and as a result of processing it with hydrogen peroxide, that is, carrying out some destruction of the polymer. Products of partial destruction of PAA at low viscosity have satisfactory adhesive ability.
It should be noted that the widespread use of 8% PAA in textile enterprises is associated with some difficulties. Even in the process of synthesis of PAA, under the influence of air oxygen and high temperature, there is a cross-linking between the resulting macromolecules. The process of crosslinking will take place during the storage of PAA.
Given the above circumstances, in particular, for the dressing of linen bases, it was recommended to use 6% PAA obtained by polymerization of 6% acryl-amide solution [7].
As noted, in the practice of dressing used and samples of polyvinyl alcohol, and this is due to the fact that PVC provides sufficient adhesion when dressing yarn, especially in the case of a mixture of natural and chemical fibers. PVC is able to form a strong shell with higher structural and mechanical resistance.
In the scientific literature some thermody-namic characteristics of the dressing process are given: these are the thermal effects of limited and
complete dissolution of PVC in water and the integral heat of interaction of the PVC dressing with cellulose [8].
For dressing, as it was established in these works, it is possible to apply PVC with different molecular weight and different number of acetate groups (or degree of saponification). PVC dressing is convenient and easy to prepare, does not require splitters and additives, and its cooking time is 1.5-2 times less than starch dressing. The concentration of PVC in the dressing solution is 2.5-3 times less than starch. In addition, aqueous solutions of PVC are not exposed to bacteria and do not cause corrosion of the equipment, easily regenerated for reuse in the process of dressing.
For preparation of the dressing cotton bases on 1000 l of the finished dressing about 30 kg of PVC is required. The relative viscosity of the dressing is 1.3; the temperature of the dressing in the trough 358K. Glue is 3%. Consumption of PVC per 1 ton of soft yarn brand 18.5-Tex is 32 kg.
It is also noted that in its dressing properties, PVC is significantly superior to starch and Na-CMC, due to its good solubility and film-forming properties. The strength and elongation of yarn, oligomannose PVC, above, and breakage in weaving is lower than the yarn, oligomannose starch dressing. The addition of glycerol (3G/l) further reduces 2-2. 5 times the stiffness of the lined yarn [9].
The disadvantage of PVC is that it can not be used for hydrophobic fibers, because it does not have sufficient adhesion to the fiber.
In [10] the composition for dressing at a relatively low temperature is recommended. It consists mainly of polyvinyl acetate and starch (or polyvinyl alcohol) in a ratio of 5: 95-70: 30. Further, the us patent is also known. It offers a dressing composition consisting of polyvinyl alcohol and polyacrylic acid molecular weight 25000-100000.
In other sources it is noted [11] that synthetic and artificial dressing products, in comparison with natural polymers, in particular, with starch, have significant advantages, both in terms of equipment performance and quality of dressing. In addition, the conditions for the implementation of the chartering itself will be very simple. In this regard, cellulose esters are more important.
Among the cellulose esters having an adhesive effect, the most suitable for the dressing process is carboxymethylcellulose (CMC) with different degrees of esterification and polymerization. It, indeed, has a number of advantages over starch. It is easier to prepare a dressing from it, since it does not require the addition of other substances (components). CMC dressing is well retained on the yarn, resistant to long-term storage and is easily removed when rinsed in hot water.
The ammonium salt of cellulose-glycolic acid acts similarly to Na-CMC. Its advantage is the possibility of plasticization due to organic amines and polyglycols, which makes it preferable to use it in the process of dressing yarn from synthetic fibers.
The authors report no conflict of interest in the article.
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