RU2168571C1 - Method for producing polypropylene twist thread (versions) - Google Patents

Abstract

FIELD: textile industry. SUBSTANCE: method involves putting together at least two polypropylene longitudinally profiled threads obtained from synthetic polypropylene films; providing twisting of threads at twisting rate of 100-200 tw/m; slubbing obtained threads by imparting twisting motion in opposite direction at twisting rate making 0.55-0.85 of initial twisting rate. According to other version, method involves twisting of each polypropylene longitudinally profiled thread, produced from propylene film, at twisting rate of 150-300 tw/m; slubbing obtained threads by imparting twisting motion in opposite direction at twisting rate making 0.65-0.9 of initial twisting rate. This version of method allows thread compactness to be increased. Besides, its physicomechanical properties are uniform throughout the whole length of it. Polypropylene thread produced by both methods may be further subjected to thermal fixation, oiling, or thermal fixation with following oiling, depending on requirements and field of usage of thread. Methods allow threads with high linear density (100-400 tex) and equiponderant structure to be produced by providing wider range of changing linear density, twisting rate, rigidity and compactness of thread. EFFECT: increased efficiency and versatility of thread. 8 cl, 2 tbl

Description

 The invention relates to the textile industry and relates to the production of yarns from synthetic polymer films, namely, twisted polypropylene yarns for general purposes with high linear density (100-400 tex).

 A known method of producing a synthetic film thread by forming a longitudinally profiled film with alternating thickenings and thinning along its width, cooling, drawing and dividing it into threads (SU 360784 A, 11.28.1972).

 The disadvantage of the yarn obtained by this method is low bending stiffness, low tensile characteristics, which limits the scope of its use in the manufacture of ropes or technical fabrics, such as tare.

 Closest to the proposed methods is a method for producing a twisted polypropylene yarn by combining two or more polypropylene film longitudinally profiled yarns and their subsequent twisting (US 3680303 A, 01/01/1972).

 The disadvantage of the thread obtained by this method is the nonequilibrium structure, which leads to the formation of sucrutin, loops and breaks in the process of its use.

 The objective of the group of inventions is the creation of methods for producing a twisted polypropylene yarn of wide purpose, high linear density, with high physical and mechanical properties and an equilibrium structure due to the ability to widely vary the linear density of the obtained yarn, its twist, rigidity and compactness.

 This technical result in a method for producing a twisted polypropylene yarn by folding two or more polypropylene film longitudinally profiled yarns and their subsequent torsion is achieved in that the torsion is carried out with a twist of 100-200 kr / m, the obtained yarns are cut and give them a twist in the opposite direction equal to 0.55-0.85 from the initial twist.

 According to the production method, the twisted polypropylene yarn can be additionally subjected to heat-setting or oiling, or heat-setting, followed by oiling, which is determined by the requirements for the thread, depending on its purpose.

 The specified technical result in a variant of the method for producing a twisted polypropylene yarn by folding two or more polypropylene film longitudinally profiled yarns and their subsequent twisting is achieved by twisting each polypropylene film longitudinally profiled yarn with a twist of 150-300 torsion / m before folding, and then obtained the threads are cut and they are told to twist in the opposite direction, equal to 0.65-0.9 from the initial twist.

 This method allows, in addition, to increase the compactness of the thread, to align its physical and mechanical properties along the length.

 The twisted polypropylene yarn obtained in this way can be further subjected to heat setting or oiling, or heat setting, followed by oiling.

 A method of obtaining a twisted polypropylene yarn is implemented as follows.

 Polypropylene film longitudinally profiled yarns are folded two or more times, and then, with the help of a torsion body, a real twist equal to 100-200 kr / m is reported. The magnitude of the reported twist is selected from the condition of giving the resulting thread the necessary strength. At a twist of less than 100 kruch / m, the strength of the thread slightly exceeds the strength of the film thread. When twisting more than 200 kruch / m, the thread is twisted, its stiffness increases, which can cause it to break.

 The resulting threads are reed. The number of additions depends on the linear density of the finished thread. After trimming, the threads are told twist in the opposite direction, while the twist is 0.55-0.85 from the original. If the ratio of the first and second twists is less than 0.55, then there is a large unevenness in strength indicators. If the ratio of the first and second twists is more than 0.85, then the unevenness of the thread increases.

 At the same time, changing the values of both the first and second twists in the indicated range, they provide the possibility of changing the stiffness of the thread within certain limits, which, in turn, allows one to obtain broad-purpose threads.

 In order to make the thread compact and align its physical and mechanical properties along the length, in the process variant, before folding, each polypropylene film film is longitudinally profiled with a twist of 150-300 torsion / m twist. This twist range, confirmed by experimental data, ensures the compactness of the thread and ensures the achievement of uniform physical and mechanical properties along the length, such as breaking load, elongation. When twisting less than 150 kruch / m, optimal compactness is not achieved, and the thread has an uneven structure. When twisting more than 300 kruch / m, the twist of the thread sharply increases, the voltage increases, which leads to fibrillation and loss of strength.

 The resulting yarns are reed, while, as mentioned above, the number of additions depends on the required linear density of the finished yarn. After trimming, to give an equilibrium structure to the threads, twist in the opposite direction equal to 0.65-0.9 from the initial one is reported. During torsion, the breaking load of the thread increases, but only up to a certain twist value. If the ratio of the first and second twist is less than 0.65, a yarn with low breaking characteristics is obtained. If the ratio of the first and second twist exceeds 0.9, then an increase in twist causes overvoltage in the threads, which leads to their fibrillation and a decrease in breaking load.

 The threads obtained by these methods have high performance characteristics. But synthetic threads having a universal purpose are currently missing. In particular, for use in the food industry, for example for strapping sausages, high equilibrium requirements are imposed on the threads, which is achieved by an additional thermal fixation.

 When using twisted polypropylene yarn as a sewing thread to reduce the coefficient of friction in the needle of the sewing machine, it is additionally oiled.

 Polypropylene film longitudinally profiled yarns are reeled and twisted on reed-twisting machines.

 Thermofixing is carried out in vacuum-vapor-filling apparatuses, and oiling is carried out according to traditional technology.

 Only with the observance of the specified twist parameters, a thread can be obtained in a wide range of linear density, having an equilibrium structure and the required stiffness.

 Table 1 shows the properties of the obtained yarns and examples of the method according to claim 1 of the formula.

 Table 2 shows the properties of the obtained yarns and examples of the method according to claim 5 of the formula.

 As can be seen from the tables, the proposed methods make it possible to obtain twisted polypropylene filaments of high linear density, with high physical and mechanical properties and an equilibrium structure. At the same time, the use of polypropylene filaments is of great economic and practical importance, since they have low hygroscopicity, do not contain low molecular weight compounds that have a carcinogenic effect on the body, and are environmentally friendly. These factors allow the use of these threads along with sewing in the medical and food industries.

Claims (8)

 1. A method of producing a twisted polypropylene yarn by folding two or more polypropylene film longitudinally profiled yarns and their subsequent torsion, characterized in that the torsion is carried out with a twist of 100 to 200 kr / m, the obtained yarns are cut and give them a twist in the opposite direction equal to 0 , 55 - 0.85 of the initial twist.  2. The method according to claim 1, characterized in that it further thermofixes the thread.  3. The method according to claim 1, characterized in that it additionally carry out the oiling of the thread.  4. The method according to claim 2, characterized in that after heat-setting carry out the oiling of the thread.  5. A method of producing a twisted polypropylene yarn by folding two or more propylene film longitudinally profiled yarns and their subsequent torsion, characterized in that before folding, each polypropylene film longitudinally profiled yarn is twisted with a twist of 150-300 torsion / m, after which the obtained yarns are pulled and tell them to twist in the opposite direction, equal to 0.65 - 0.9 from the initial twist.  6. The method according to claim 5, characterized in that it further thermofixes the thread.  7. The method according to claim 5, characterized in that it additionally carry out the oiling of the thread.  8. The method according to claim 6, characterized in that after heat-setting carry out the oiling of the thread.

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