RU2334027C1 - Method of manufacturing high-strength fiber from ultra-high molecular polyethylene - Google Patents

Abstract

FIELD: soft wares, paper.

SUBSTANCE: invention concerns receiving of high-strength, high-modulus fibers made from flexible polymers according to method gel-technology, particularly, polyethylene, and can be used for manufacturing of light compound material, antistrike protective envelopes, ropes, wires, sports outfit, product of medical purpose, etc. Method includes stages of polymer solution in liquid paraffin, forming, plasticification stretching at higher temperature, orientational thermo-stretching, extraction and drying. Orientational thermo-stretching is implemented not less than during four stages. The first two are implemented in liquid paraffin medium, and further are implemented in noble gas or air medium. Given stretching temperature which is equal to ratio of stretching temperature at one stage to the fiber fusion temperature after previous stretching stage T_s(n)/T_m(n-1), is changing from the first stage to the last from 0.82 till 0.95. Given stretching multiplicity, equal to ratio of the orientational stretching multiplicity at one stage to the stretching multiplicity at previous stage λ_s(n)/λ_s(n-1), for the first stage it is equal to 1.05-1.25, for the second 0.33-0.36, for the third - 0.85-0.92, for the fourth stage - 0.81-0.90. Temperature-time stretching criteria K⁰ _t,τ, are at the first and second stage of orientational stretching in the range of -5.9 till -5.5, and for the third and the fourth stages of orientational stretching in the range of -6.3 till -6.0. Fiber allows high mechanical rates in conjunction with low density (0.980-0.986 g/cm³).

EFFECT: receiving of fiber with high mechanical rates and low density.

2 cl, 1 tbl, 4 ex

Description

The invention relates to the production of high-strength, high-modulus yarns from flexible chain polymers according to the method of gel technology. The multifilament yarns obtained using this method from ultra-high molecular weight polyethylene (SVM PE) are intended for the production of light composite materials, shockproof protective shells, ropes, nets, sports equipment, medical devices, etc.

A known method for producing a high-strength high-modulus multifilament yarn from ultra-high molecular weight polyethylene (US Patent 4,551,296, D01F 6/00, published 05.11.1985), in which a polymer solution in paraffin oil is molded by gel technology, and the molded gel is not washed from the solvent - thread, or completely washed from the solvent and dried thread, is subjected to one- or two-stage orientation thermal stretching in tubes filled with hot inert gas. Due to the weak heat exchange between the filament and the hot gas medium, the heating of the filaments located outside and inside the complex filament occurs non-uniformly. This leads to a sharp decrease in the strength characteristics of the thread as the number of filaments increases.

A known method for producing high-strength ultra-high molecular weight polyethylene filament according to the gel technology method includes the steps of dissolving the polymer in paraffin oil, extruding the spinning solution through a die, cooling the spinning jets in an isopropanol bath to form a gel, and the three-stage orientation thermal elongation not washed from the solvent (48-38 ) -filament gel filament in a paraffin oil environment, washing it from oil with hexane, drying from hexane and winding on spools (RF Patent 1796689, D01F 6/04, publ. 03.03.1993).

The specified method for producing high-strength yarn from ultra-high molecular weight polyethylene is taken as a prototype.

The disadvantage of this method is that the stretching of the filament in a liquid coolant - paraffin oil, which is a polymer solvent, does not allow multifilament filaments with a high level of strength indicators, since the presence of a solvent in the composition of the polymer system does not contribute to the dense packing of elements formed during orientation stretching of the supramolecular structure and is accompanied by the formation of pores.

An object of the present invention is to provide a method for producing a multifilament multifilament yarn from ultra-high molecular weight polyethylene (CBM PE), which allows one to obtain a yarn with a high level of elastic strength due to the gradual formation of a perfect highly oriented polymer structure.

The problem in this invention is solved due to the fact that a method of multi-stage thermal drawing of CBM PE threads has been developed, in which, after preliminary plasticization drawing, its orientation thermal drawing is carried out in four stages. The first two stages are carried out in paraffin oil, and the subsequent stages in an inert gas or air. The reduced drawing temperature equal to the ratio of the temperature of the drawing of the thread at one stage or another to the melting temperature of the thread that has passed the previous stage of drawing T _{in (p)} / T _{m (p-1)} varies from the first stage to the last from 0.82 to 0, 95, and T _{m (p-1)} after plasticization drawing is 139 ± 2 ° C. The ratio of the orientation stretch ratio at one stage or another to the stretch ratio at the previous stage, λ _{in (p)} / λ _{in (p-1)} for the first stage is in the range from 1.05 to 1.25, for the second stage in the range from 0 , 33 to 0.36, for the third stage in the range from 0.85 to 0.92, for the fourth stage in the range from 0.81 to 0.90. Moreover, the temperature-time criterion for pulling K ⁰ _{t, τ} is in the range from -6.3 to -5.5.

The optimal value of the temperature-time criterion K ⁰ _{t, τ} for the first and second stages of orientational thermal traction of CBM PE gel threads carried out in paraffin oil is in the range from -5.9 to -5.5, and for the third and fourth stages Orientational thermal elongation completely washed from solvent and dried CBM PE filaments, which are carried out in an inert gas or air, in the range from -6.3 to -6.0.

The proposed method for producing high-strength filaments from ultra-high molecular weight polyethylene allows us to improve the conditions of orientational thermal elongation, aimed at the destruction of the elements of the original crystalline structure and the creation of a new, more advanced highly oriented structure, the basis of which are crystallites on straightened chains.

It is known that uniaxial tension of filaments based on crystallizing flexible-chain polymers is carried out in the interval between the glass transition temperature of amorphous regions and the melting temperature of polymer crystallites (Slutsker A.I. Oriented state. // Encyclopedia of polymers. M., 1977, V.2, p. 515 ) Under the influence of temperature and external tensile stress, the initial crystallites are partially destroyed. Part of the segments of the molecular chains goes from a crystalline state to an amorphous (highly elastic) state. Since the external tensile stress creates a preferential orientation direction in the polymer, the molecular segments that have transferred to the amorphous state begin to straighten and line up along this direction due to conformational thermal motion into an ordered ensemble (gauche-trans transitions). With the ordering of the emerging structure, mainly due to orientational crystallization (Slutsker A.I. Oriented state. // Encyclopedia of Polymers. M., 1977, Vol. 2, p. 515, Mandelkern L. Crystallization of polymers. M.-L. 1966), the conformational movement of chains is inhibited, the process of structural transformations self-extinguishes, and the newly formed structure is fixed. Due to the fact that due to the fixation of the structure, the polymer becomes solid, and not highly elastic, as at the beginning of stretching, the stretching can completely stop, and the thread breaks long before reaching a high chain orientation. To continue the process of orientational drawing and to obtain a new structure (more perfect than the previous one), it is necessary to increase the segmental mobility of macromolecules in both crystalline and amorphous regions of the polymer. This can be achieved in two ways: by increasing the tensile temperature and / or by reducing the rate of deformation of the system (by increasing the duration of external mechanical stress). A sharp increase in temperature and / or a decrease in the strain rate is not permissible, since relaxation processes are accelerated, which contribute to disorientation of molecular segments, which prevail over processes leading to an improvement in order.

To obtain a material with a highly ordered structure and a high level of elastic strength indicators, the temperature and strain rate of the polymer object must be optimized (mutually).

, а в качестве главного критерия К⁰ _t,τ, обобщающего влияние температуры и скорости деформации, - логарифм приведенной средней скорости деформации

. Практическим результатом применения метода температурно-временного приведения является построение обобщенной корреляционной зависимости прочности и модуля упругости предельно вытянутых при различных условиях образцов полимера от температурно-временного критерия K⁰ _t,τ. Коррекция K⁰ _t,τ в область оптимальных значений обычно осуществляется за счет изменения линейных скоростей растяжения нити, температуры, а также длины зоны вытягивания.A method for evaluating the joint effect of temperature and the rate of external deformation on the relaxation and mechanical behavior of amorphous and crystallizing polymer systems is known as the principle of temperature-time superposition (Yanovsky, G.G. Superposition principle. // Encyclopedia of Polymers. M., 1977, V.3, p. 567). An important practical application of this principle is the method of temperature-time reduction (Napasnikov V.P. Patterns of uniaxial tension in the process of stretching chemical fibers: Diss. Candidate of Technical Sciences. Kalinin, 1983; Fikhman VD Uniaxial tension of melts and polymer solutions: Orientation phenomena in solutions and polymer melts. M., 1980, p. 229). According to this method, the relationship between the behavior of the polymer system and temperature is described by the coefficient (factor) of reduction α _t , which is calculated using the Williams-Landel-Ferry equation (Ferry J. Viscoelastic properties of polymers. M., 1963). The average strain rate is used as a parameter normalizing the temporary tensile regime.

, and as the main criterion K ⁰ _{t, τ} , generalizing the influence of temperature and strain rate, is the logarithm of the reduced average strain rate

. The practical result of applying the temperature-time reduction method is the construction of a generalized correlation between the strength and elastic modulus of polymer samples elongated under various conditions from the temperature-time criterion K ⁰ _{t, τ} . Correction of K ⁰ _{t, τ} to the region of optimal values is usually carried out by changing the linear rates of stretching of the thread, temperature, and also the length of the drawing zone.

The proposed method contains the following stages:

1) preparing a suspension of CBM PE powder in a high-temperature solvent (paraffin oil);

2) preparation of a spinning polymer solution;

3) forming a gel thread;

4) plasticizing stretching of the gel thread;

5) orientation thermal elongation of the gel filament in a polymer solvent medium;

6) washing the thread from the solvent using an extractant;

7) drying the thread from the extractant;

8) orientational thermal drawing of a dry thread in a gas medium;

9) rewind the finished thread on the commodity spools.

A distinctive feature of the proposed method is that at first two stages of multistage orientational thermo-traction are carried out using non-washed solvent-based CBM PE gel filament in a liquid coolant, which is a polymer solvent - paraffin oil, and then the two subsequent stages of orientational thermo-traction - using washed from solvent and dried CBM PE filaments in a medium of hot inert gas or air. Intensive heat transfer between a hot solvent acting as a heat carrier and a solvent that is part of a gel filament, as well as a sharp (40-45) -fold decrease in the linear density (cross-sectional area) of a dry filament fed to a gas in the medium, provide fast and uniform heating of individual filaments of complex CBM PE filaments both at the stages of drawing in a liquid and in a stream of hot inert gas or air. This makes it possible to draw complex CBM PE filaments consisting of a large number of filaments.

When the heat-transfer fluid is drawn in the medium, there is a syneresis, i.e. extraction of solvent from a gel thread. The volume of the solvent to be regenerated, which after extraction from the yarn remains mainly on its surface, as a result of this is reduced, not less than 8 times, compared with the initial freshly formed gel thread.

The difference of the proposed method is also that in a wide range of temperatures and average strain rates, the process of multi-stage orientational drawing of CBM PE filaments is carried out in accordance with the principle of temperature-time superposition and is characterized by optimal values of the temperature-time criterion. The temperature-time criterion K ⁰ _{t, τ} is determined using the well-known Williams-Landel-Ferry equation (Ferry J. Viscoelastic properties of polymers. M., 1963; Fax T., Gratch S., Loshek S. Viscosity of polymers and their concentrated solutions : Rheology, M., 1962, p. 528-536):

- коэффициент приведения, характеризующий влияние температуры в условиях деформирования на коэффициент трения сегментов молекулярных цепей, находящихся в аморфном (высокоэластическом) состоянии;Where

- reduction coefficient characterizing the influence of temperature under conditions of deformation on the coefficient of friction of segments of molecular chains in an amorphous (highly elastic) state;

T is the temperature of the polymer under deformation, ° C;

T _s is the reduction temperature exceeding the glass transition temperature of the polymer (T _g ) by 50 ± 4 ° С, while the value of T _{g is} taken to be -20 ° С and corresponds to the average temperature of the β-relaxation transition of polyethylene associated with the onset of mobility of molecular chain segments in amorphous phase;

8.86 and 101.6 are empirical constants;

- средняя скорость деформации, с^-1;

- average strain rate, s ^-1 ;

V _{(n + 1)} and V _(n) are the linear velocities of the thread after and before stretching at one or another stretching stage, m / s;

L is the length of the stretch zone, m

It was found that in the first two stages of orientational drawing of CBM PE gel filaments carried out in a medium of hot liquid coolant, the optimal values of the criterion К ⁰ _{t, τ} are in the range from -5.9 to -5.5, and in the next two stages of orientational stretching the solvent washed and dried CBM PE filaments carried out in a hot inert gas or air, in the range from -6.3 to -6.0. At the indicated values of the criterion K ⁰ _{t, τ} , the conditions are provided for the gradual formation of a perfect highly oriented polymer structure and the highest elastic strength indicators of an elongated CBM PE thread.

A distinctive feature of the proposed method also lies in the fact that, while maintaining the optimal values of the temperature-time criterion and a stepwise change in the temperature regime of the four-stage orientation drawing for each stage, the optimal ranges of the reduced temperature and the reduced drawing ratio were established, specifying the conditions for uniaxial tension of the CBM PE filament and providing the finished product (filament) with a highly ordered structure and higher E uprugoprochnostnymi properties compared to the known analogues.

The structure of the SVM PE filaments was evaluated after each of the four stages of orientational thermal elongation was completed by X-ray diffraction, polarized Fourier infrared (IR) spectroscopy, and differential scanning calorimetry (DSC). Using the X-ray diffraction patterns, the average longitudinal crystallite size (L ₀₀₂ ) was calculated. Based on the data of polarization IR spectroscopy, the degree of molecular orientation <cos ² θ> was determined, which characterizes the orientation of the straightened chain segments in both the amorphous and crystalline regions of the polymer (here θ is the angle between the axis of the straightened chain segment and the orientation axis). Using DSC thermograms taken under isometric conditions at a heating rate of 10 ° C / min, the average melting temperature (T _m ) was measured, and the degree of crystallinity of the filament (χ) was measured by the melting enthalpy. All measurements were carried out on yarn washed from solvent and dried samples.

The reduced drawing temperature for each of the four stages of the orientational drawing process was calculated by the ratio of the drawing temperature T _{in (p)} at one stage or another to the melting temperature of the CBM PE filament T _{m (p-1)} , which went through the previous drawing stage. It was found that for the first stage of orientational drawing of CBM PE filaments, the optimal values of the reduced temperature range from 0.82 to 0.85, for the second stage from 0.84 to 0.87, for the third stage from 0.87 to 0.89, and for the fourth ranging from 0.92 to 0.95. In this case, before orientational drawing, the thread passes the plasticizing drawing stage with an interval of the reduced temperature in the range from 0.77 to 0.80.

The reduced stretching ratio for each of the four stages of the orientational drawing process of the CBM PE filament was calculated as the ratio of the orientation drawing ratio at each specific stage λ _{in (p)} to the drawing ratio at the previous stage λ _{in (p-1)} . For the first stage of orientational drawing of CBM PE yarns, the optimal values of the reduced stretch ratio are in the range from 1.05 to 1.25, for the second stage in the range from 0.33 to 0.36, for the third stage in the range from 0.85 to 0 , 92, and for the fourth stage in the range from 0.81 to 0.90. At the same time, at the stage of plasticization drawing, the reduced drawing ratio is in the range from 4.4 to 4.6.

Changes in the structural and elastic-strength properties of CBM PE filaments during four-stage orientational drawing at optimal values of reduced drawing temperatures and reduced drawing ratios realized under the conditions of the present invention are presented in table 1.

If, at least at one of the stages of four-stage orientational drawing, the reduced drawing temperature is outside the lower or upper limits of the optimal ranges of values indicated in Table 1, it is impossible to form an oriented ordered polymer structure and to obtain a yarn with high elastic strength properties (i.e., with high strength σ _p and initial elastic modulus E).

In this case, if the reduced stretching temperature is lower than the optimal range of values indicated in Table 1, then the destruction of the elements of the crystal structure and the transition of some molecular segments from the ordered state to a highly elastic (amorphous) state occurs in the thread entering one or another stretching stage, in insufficient measure. As a result of this, the stretching stops due to the breakage of the thread at low multiplicity values, and the structural (T _m , χ, L ₀₀₂ , <cos ² θ>) and elastomeric (σ _p , Е) indices of elongated samples become lower than those indicated in Table 1.

If the reduced stretching temperature is higher than the optimal ranges of values indicated in Table 1, then relaxation processes that contribute to disorientation of molecular segments in the amorphous phase will prevail over processes leading to an improvement in order. For this reason, the structural (Т _m , χ, L ₀₀₂ , <cos ² θ>) and elastic-strength (σ _p , Е) indicators of elongated yarn samples become lower than those presented in Table 1.

If at least one of the stages of four-stage orientational drawing of CBM PE filaments, the given stretch ratio extends beyond the lower and upper boundaries of the optimal ranges of values indicated in table 1, and the temperatures are maintained at the same time, obtaining a filament with high strength and initial elastic modulus becomes impossible.

Each stage of orientational drawing is characterized by processes occurring both at the molecular level and at the level of supramolecular formations.

So, at the first and second stages of orientational drawing in a fluid of a heat-transfer medium under the influence of temperature and external tensile stress, an intensive decomposition of the initial supramolecular formations (crystallites on folded chains) and the formation of a new structure oriented along the axis of tension occur. With the ratio of T _B1 / T _{m pred.} less than 0.82, and T _b2 / T _m1 less than 0.84, the proportion of molecular segments passing from the crystalline phase to the amorphous is insufficient. The thread breaks at low stretch ratios. The degree of crystallinity χ, the longitudinal crystallite size L _002, and the degree of molecular orientation <cos ² θ> become lower than the values indicated in Table 1. At T _b1 / T _{m pred.} more than 0.85, and T _b2 / T _m1 more than 0.87 for the first and second stages, intensification of relaxation processes that impede the orientation of the molecular segments in the amorphous phase. Growth χ, L ₀₀₂ , <cos ² θ> does not occur. For the same stages with λ _b1 / λ, _pre less than 1.05 and λ _b2 / λ _b1 less than 0.33, the molecular orientation in the yarn is relatively low. As a result, the values of χ, L ₀₀₂ , <cos ² θ> decrease and become lower than the range of values indicated in Table 1. In the case where λ _c1 / λ _Pre 1.25 and λ _s2 / λ _c1 more than 0.36, there is excessive growth of tensile stress and consequently thread breakage.

Subsequent stretching of the dry filament in a hot gas medium leads to even deeper decomposition of the initial structure and is accompanied by an increase in the orientation and longitudinal size of the newly formed crystallites, as well as an increase in the degree of crystallinity and a sharp decrease in porosity. As the stretching factor of the filament in the gas medium increases, the longitudinal size of the crystallites gradually increases due to the displacement of the crystallization front (i.e., the defective transition region adjacent to the ends of the crystallites) inside the amorphous interlayer. As a result, precrystallization of intrafibrillar amorphous regions occurs. The degree of crystallinity of the thread reaches high values, and the oriented system becomes less defective and more durable. When the ratio of T _B3 / T _{m2 is} less than 0.87 and T _B4 / T _{B3 is} less than 0.92, the mobility of the molecular segments in both the crystalline and amorphous phases of the polymer decreases, and the stretching ratio decreases. χ, L ₀₀₂ , <cos ² θ> become lower than the values specified in table 1. When the ratio of T _B3 / T _m2 more than 0.89 and T _B4 / T _m3 more than 0.95 there is a partial or complete melting of the elements of the crystalline structure and the bonding of filaments. The structural parameters of elongated samples χ, L ₀₀₂ , <cos ² θ> sharply decrease. At λ _b3 / λ _b2 less than 0.85 and λ _b4 / λ _b3 less than 0.81, the advance of the crystallization front deep into the amorphous layer is not enough and the values χ, L ₀₀₂ , <cos ² θ> indicated in table 1 are not achieved. When λ _b3 / λ _{b2 is} more than 0.92 and λ _b4 / λ _{b3 is} more than 0.90, the tensile stress increases and the stability of the pull process decreases (first, the breakage of individual filaments grows, and then, as a consequence, the breakage of the thread itself).

A method of obtaining a high-strength thread from CBM PE is carried out according to the invention as follows. The measured volume of solvent (paraffin oil) and a weighed sample of CBM PE powder with a molecular weight of 3 × 10 ⁶ -5 × 10 ⁶ g / mol are loaded into a slurry preparation apparatus with a rotating paddle mixer. The resulting suspension is degassed under reduced pressure, and then flows through an open valve into a supply tank, within which an inert atmosphere is maintained. From the supply tank, the suspension enters a twin-screw extruder, where at a temperature equal to 1.25-1.32 from the melting point of the CBM PE, the powder particles first melt, and then, swelling in the solvent, increase in size and merge with each other, forming a system with nonequilibrium polymer concentration. Due to the pressure developed by the extruder, the resulting mixture is transferred to the apparatus for preparing a homogeneous spinning solution equipped with a highly efficient mixing device. The solution leaving the apparatus, containing 2-6% of the polymer, enters the molding unit equipped with four or eight sets of metering pumps, and dies with a total number of openings 512 or 1024. The jets of hot spinning solution flowing from the openings of the dies go into an open unheated container filled with paraffin oil with a temperature of 0.20-0.35 of the melting point of CBM PE, where, as a result of sudden cooling, they lose fluidity and turn into a gel state. The resulting gel thread, consisting of 512 or 1024 individual filaments, is continuously fed for plasticization stretching, which is carried out in a bath with paraffin oil, heated to a temperature of 0.75-0.80 of the melting point of the CBM PE, and then taken into a cylindrical container, mounted on a rotating disk of the receiving device.

находятся для первой и второй стадий в пределах от -5,9 до -5,5. В условиях сохранения оптимальных значений K⁰ _t,τ приведенная температура вытягивания T_в(п)/Т_m(п-1) находится для первой стадии в интервале от 0,82 до 0,85, а приведенная кратность вытягивания λ_в(п)/λ_в(п-1) в интервале от 1,05 до 1,25. На второй стадии значения приведенной температуры изменяются от 0,84 до 0,87, а приведенные кратности вытягивания от 0,33 до 0,36. Прошедшую первую и вторую стадии ориентационного вытягивания нить крестообразно наматывают на бобину приемно-намоточной машины, а затем подают на операцию отмывки нити от растворителя.Containers with gel thread that has undergone preliminary stretching are transferred to a four-stage orientation thermal stretching. At the same time, in the first two stages of orientational drawing, a gel thread not washed from the solvent is used, the tension of which is carried out in a medium of hot liquid coolant, the function of which is performed by the solvent of CBM PE - paraffin oil. The gel thread, continuously removed from the container mounted on the pallet, is sequentially passed through the receiving, intermediate and output semivlets with adjustable speed of the biscuits and two baths located between them with thermostated oil, in which the thermo-extension takes place. Orientational thermal elongation of the gel filament in a paraffin oil medium is realized in accordance with the principle of temperature-time superposition. Optimal values of the temperature-time criterion

are for the first and second stages in the range from -5.9 to -5.5. Under conditions of preserving the optimal values of K ⁰ _{t, τ, the} reduced drawing temperature T _{in (p)} / T _{m (p-1)} is for the first stage in the range from 0.82 to 0.85, and the reduced drawing ratio λ _{in (p)} / λ _{in (p-1)} in the range from 1.05 to 1.25. At the second stage, the values of the reduced temperature vary from 0.84 to 0.87, and the given stretching ratios from 0.33 to 0.36. The first and second stages of orientational drawing have passed, the thread is wound crosswise onto the bobbin of the receiving-winding machine, and then it is fed to the operation of washing the thread from the solvent.

Complete removal of the solvent from the yarn is achieved by repeated washing with an extractant gasoline.

The thread dried from gasoline is then fed to two stages of additional orientation drawing, which are carried out in heat chambers filled with hot inert gas or air. A dry thread, consisting of 512 or 1024 individual filaments, is wound from a bobbin mounted on the creel and sequentially passed through receiving, intermediate and output semelers with increasing speed of biscuits and two heat chambers located between them filled with a thermostatically controlled inert gas or air, and then wound on the take-up reels of the winder. Due to the fact that a filament with a linear density of 40-45 times lower than that of the initial one is fed to the final stages of orientational drawing, heating of its individual filaments to the required temperature occurs uniformly and in a short period of time in a stream of hot gas. The optimal values of the temperature-time criterion K ⁰ _{t, τ} are for the third and fourth stages in the range from -6.3 to -6.0. In this case, the reduced drawing temperature T _{in (p)} / T _{m (p-1)} is for the third stage in the range from 0.87 to 0.89, and the reduced drawing ratio λ _{in (p)} / λ _{in (p-1)} in the range from 0.85 to 0.92. At the fourth stage, the values of the reduced temperature are in the range from 0.92 to 0.95, and the reduced stretch ratios are in the range from 0.81 to 0.90. The finished SVM PE thread, which has passed the final stage of orientational thermal drawing in a hot gas medium, is rewound from the receiving reels of the winding device to commodity spools and sent to the consumer.

The invention is illustrated by the following examples.

EXAMPLE 1

Powder CBM PE with a molecular weight of 4.6 × 10 ⁶ g / mol and a melting temperature T _m equal to 137.0 ° C, is mixed with paraffin oil. The resulting suspension is degassed and transferred with stirring and heating to a temperature of (1.27-1.29) T _m in a state of a homogeneous dope containing 5% polymer. The solution is extruded with a flow rate of 5 × 10 ^-6 m ³ / s through four dies with a total number of holes 512. The diameter of each hole is 5 × 10 ^-4 m. The jets leaving the dies are cooled at a temperature of 0.20 T _m in an open container with paraffin oil and the resulting gel thread is fed for plasticization drawing into a bath with paraffin oil heated to a temperature of 0.80 T _m . An elongated 4.6 gel stretch is taken into a cylindrical container to a preliminary pull ratio. The gel thread from the container enters into a two-stage orientation thermal extension, which is carried out in two successively arranged baths filled with a heat transfer fluid - paraffin oil. The process is carried out with an optimal combination of temperature-time parameters. The optimal values of the temperature-time criterion K ⁰ _{t, τ} are at the first and second stages of drawing in the range from -5.9 to -5.6. Moreover, for the first stage, the reduced temperature T _in1 / T _{m pred.} equal to 0.850, and the given multiplicity of stretching λ in ₁ / λ _{in advance.} is 1.245. In the second stage, the value of the reduced temperature T _b2 / T _m1 is 0.860, and the reduced multiplicity λ _b2 / λ ₁ is 0.334. The elongated thread is washed from the solvent (paraffin oil). Complete removal of oil is achieved by washing the filament five times with extraction gasoline. The relative amount of extracted oil is 280% by weight of the polymer in the yarn. Then, the thread dried from gasoline is subjected to an additional two-stage orientation thermal stretching, which is carried out in two sequentially located heat chambers filled with thermostated hot air. The process is carried out with an optimal combination of temperature-time parameters. The optimal values of the temperature-time criterion K ⁰ _{t, τ} are at the third and fourth stages of stretching in the range from -6.3 to -6.0. At the same time, for the third stage, the reduced temperature Т _в3 / Т _m2 is 0.89, and the reduced stretching _ratio λ _в3 / λ _в2 is 0.92. In the fourth stage, the optimal value of the reduced temperature T _b4 / T _m3 is 0.95, and the reduced multiplicity λ _b4 / λ ₃ is 0.81. A thread that has passed the fourth stage of thermal elongation has the following structural indicators: crystallinity χ - 94.9%; the degree of molecular orientation <cos ² θ> 0.93, the longitudinal crystallite size L ₀₀₂ is 24 nm. In this case, diffusion equatorial scattering on the small-angle X-ray diffraction pattern disappears, therefore, pores in the filament are practically absent.

Finished products, i.e. A 512-filament yarn with the indicated structural characteristics has the following specific mechanical characteristics: tensile strength σ _p - 430 cN / tex (4.25 GPa), initial elastic modulus E - 15600 cN / tex (154 GPa).

EXAMPLE 2

A suspension of CBM PE powder in paraffin oil is transferred to the state of a homogeneous spinning solution as in Example 1. A solution containing 5% polymer is extruded with a flow rate of 10 × 10 ^-6 m ³ / s through eight dies with a total number of openings of 1024. The diameter of each hole is 5 × 10 ^-4 m. The jets emanating from the spinnerets are cooled at a temperature of 0.35T _m in an open container with paraffin oil, and the resulting gel thread, consisting of 1024 individual filaments, is fed for plasticization drawing into a bath with paraffin oil heated to a temperature 0.75 T _m A gel thread extended to a pre-stretch ratio of 4.4 is taken into a container. From the container, the gel thread enters a two-stage orientation thermal extension, which is carried out in two bathtubs filled with a liquid coolant - paraffin oil. The values of the temperature-time criterion K ⁰ _{t, τ} are at the first and second stages of drawing in the range from -5.8 to -5.5. Moreover, for the first stage, the reduced temperature T _in1 / T _{m pred.} equal to 0.82, and the reduced multiplicity of stretching λ in ₁ / λ _{in advance.} is 1.05. At the second stage, the optimal value of the reduced temperature T _b2 / T _m1 is 0.84, and the reduced multiplicity λ _b2 / λ ₁ is 0.355.

The elongated thread is washed from the solvent (paraffin oil), dried and subjected to an additional two-stage orientation thermal stretching, which is carried out in two successive heat chambers filled with thermostated hot air. The values of the temperature-time criterion K ⁰ _{t, τ} are at the third and fourth stages of stretching in the range from -6.2 to -6.0. Moreover, for the third stage, the reduced temperature T _b3 / T _m2 is 0.87, and the reduced stretch _ratio λ _b3 / λ _b2 is 0.85. In the fourth stage, the optimal value of the reduced temperature T _b4 / T _m3 is 0.92, and the reduced multiplicity λ _b4 / λ ₃ is 0.885. A thread that has passed the fourth stage of thermal elongation has the following structural indicators: crystallinity χ - 93.1%; the degree of molecular orientation <cos ² θ> 0.92, the longitudinal crystallite size L ₀₀₂ is 23 nm. Pores in the thread are practically absent.

Finished products, i.e. A 1024-filament yarn with the indicated structural characteristics has the following specific mechanical characteristics: tensile strength σ _p - 390 cN / tex (3.84 GPa), initial elastic modulus E - 14100 cN / tex (139 GPa).

EXAMPLE 3

Obtaining a 512-filament gel filament, including preparing a suspension of CBM PE powder in paraffin oil, transferring the suspension to the state of a homogeneous spinning solution, as well as the stage of molding and plasticizing stretching of the gel filament, was carried out in the same way as in Example 1. The temperature-time values criterion K ⁰ _{t, τ} are in the first and second stages of drawing in the range from -5.8 to -5.5. Moreover, for the first stage the reduced temperature T _in1 / T _{m pred.} equal to 0.82, and the reduced multiplicity of stretching λ in ₁ / λ _{in advance.} - 1.05. At the second stage, the optimal value of the reduced temperature T _b2 / T _m1 is 0.84, and the reduced multiplicity λ _b2 / λ ₁ is 0.355. The values of the temperature-time criterion K ⁰ _{t, τ} are at the third and fourth stages of stretching in the range from -6.2 to -6.0. Moreover, for the third stage, the reduced temperature T _b3 / T _m2 is 0.87, and the reduced stretch _ratio λ _b3 / λ _b2 is 0.85. In the fourth stage, the optimal value of the reduced temperature T _b4 / T _m3 is 0.92, and the reduced multiplicity λ _b4 / λ ₃ is 0.885. A thread that has passed the fourth (final) stage of orientational thermal elongation has the following structural indicators: crystallinity χ - 93.8%; the degree of molecular orientation <cos ² θ> 0.92, the longitudinal crystallite size L ₀₀₂ is 23 nm. Pores in the thread are practically absent.

Finished products, i.e. A 512-filament yarn with the indicated structural characteristics has the following specific mechanical characteristics: tensile strength σ _p - 405 cN / tex (3.98 GPa), initial elastic modulus E - 14800 cN / tex (146 GPa).

EXAMPLE 4 (prototype).

Obtaining a 512-filament gel thread, including preparing a suspension of CBM PE powder in paraffin oil, transferring the suspension to a state of homogeneous spinning solution, as well as the stage of molding, plasticizing drawing, two-stage orientation thermal drawing in paraffin oil, washing the thread from oil with gasoline and drying, carried out analogously to example 1.

Additional orientational pulling of the CBM PE filament in a hot inert gas or air environment is not carried out.

The thread dried from gasoline has the following structural indicators: crystallinity χ - 79.8%; the degree of molecular orientation <cos ² θ> 0.88, the longitudinal crystallite size L ₀₀₂ is 22 nm. In addition, powerful diffusion scattering is responsible for the appearance of developed porosity at the equator of the small-angle X-ray diffraction pattern of the filament. Pores have a pronounced shape anisotropy with the longitudinal axis of the yarn oriented along the axis and very small (1-10 nm) transverse dimensions.

A 512-filament yarn with the indicated structural characteristics has the following specific mechanical characteristics: tensile strength σ _p - 290 cN / tex (2.84 GPa), initial elastic modulus E - 10500 cN / tex (103 GPa).

The process of orientational thermal traction of an SVM PE filament, consisting of a large number of individual filaments, in four stages, two of which are carried out in a medium of a heat-transfer fluid (paraffin oil), and two in a medium of hot inert gas or air, and the temperature-optimal temporary tension parameters provide the conditions for obtaining a finished yarn with a highly oriented, highly ordered structure and uniquely high tensile strength and initial elastic modulus (table ca 1) components 390-430 cN / tex (3,84-4,25 GPa) and 14100-15600 cN / tex (139-154 GPa) respectively.

The combination of uniquely high mechanical properties with low density (0.980-0.986 g / cm ³ ) allows the use of CBM PE threads obtained by the implementation of the invention as a reinforcing element of impact-resistant structural plastics (composites) used in those branches of modern technology where the task of reducing the weight of the product is a priority.

Table 1
Changes in the structural and elastic-strength properties of CBM PE filaments under optimal conditions of orientation thermal traction Stage name T _{in (p)} / T _{m (p-1)} λ _{in (p)} / λ _{in (p-1)} T _{m (n),} ° C χ,% L ₀₀₂ , nm <cos ² θ> σ _p , cN / tex E, cN / tex Source sample - - 137.0 73.0 12 0.33 - - Pre-stretching in paraffin oil 0.77-0.80 4.4-4.6 139.0-139.2 70.9-71.6 13-14 0.42-0.44 35-50 240-320 The first stage of drawing in the environment of paraffin oil 0.82-0.85 1.05-1.25 152.1-152.3 76.1-77.8 19-20 0.87-0.88 200-230 5200-6400 The second stage of drawing in the environment of paraffin oil 0.84-0.87 0.33-0.36 155.9-156.2 78.3-79.9 21-22 0.87-0.88 260-290 9000-10500 The third stage of drawing in an inert gas or air 0.87-0.89 0.85-0.92 156.6-156.9 85.6-88.2 22-23 0.90-0.91 340-370 12400-13600 The fourth stage of drawing in an inert gas or air 0.92-0.95 0.81-0.90 156.6-156.9 93.1-94.9 23-24 0.92-0.93 390-430 14100-15600 Where: T _{in (p)} / T _{m (p-1)} - reduced drawing temperature; T _{m (p)} is the melting temperature of the thread after the fifth stage of drawing, ° C; T _{in (p)} is the temperature at the pth stage of drawing, ° C; λ _{in (p)} / λ _{in (p-1)} - reduced stretch ratio; λ _{to (n)} λ and _{a (n-1)} - multiplicity pulling on the nth and (n-1) stages; χ is the crystallinity degree of the filament washed from the solvent,%; L ₀₀₂ — longitudinal size of crystallites in a thread, nm; <cos ² θ> is the degree of molecular orientation of the straightened chain segments along the tensile axis; σ _p is the strength of the thread, SN / Tex; E is the initial modulus of elasticity, cN / tex.

Claims (2)

1. A method of producing a high-strength yarn from ultra-high molecular weight polyethylene using gel technology, which includes the steps of dissolving the polymer in paraffin oil, molding, plasticizing drawing at elevated temperatures, orientational thermal elongation, extraction and drying, characterized in that the orientational thermal elongation is carried out in four stages, of which the first two stages are performed in a paraffin oil medium, and the next in an inert gas or air medium, while the reduced temperature of the orientational extract Bani, equal to the ratio drawing temperature in one stage to the melting temperature of the filament after drawing previous step, _{T (n)} / T _{m (n-1)} is changed from the first stage to the last from 0.82 to 0.95, wherein T _{m ( p-1)} after plasticization stretching is 139 ± 2 ° C, and the reduced stretching ratio equal to the ratio of the orientation stretching ratio at one stage to the stretching ratio at the previous stage, λ _{in (p)} / λ _{in (p-1)} is for the first stage 1 , 05-1.25, for the second stage 0.33-0.36, for the third stage 0.85-0.92, for the fourth stage 0.81-0.90, and the temperature-time criterion for pulling K ⁰ _{t, τ} , is in the range from -6.3 to -5.5. 2. The method according to claim 1, characterized in that the optimal value of the temperature-time criterion K ⁰ _{t, τ} is for the first and second stages of orientation thermal traction in the range from -5.9 to -5.5, and for the remaining stages - ranges from -6.3 to -6.0.