RU1772241C - Method for production of carbon textile filler for composite materials - Google Patents

Abstract

Usage: the manufacture of carbonaceous-modular textile fillers. SUMMARY OF THE INVENTION: An initial tow of linear density of 850-13300 tex from polyacrylonitrile filaments is thermostabilized in an oxygen-containing medium until its density of 1350-1380 kg / m3 is reached and the tow is stapled. Immediately after the stapling of the staple fiber tow, the yarn is formed on the rotor spinning machine. A textile web is formed from the obtained yarn followed by its high temperature treatment in an inert medium. 1 tab.

Description

The invention relates to a technology for the manufacture of high-modulus textile fillers based on polyacrylonitrile (PAN) fibers in the form of fabric, knitwear, non-woven materials, which are reinforcing fillers of composite materials, and technical fabrics.

The closest technical solution is the method of producing a filler, which consists in thermostabilization of the initial PAN fibers, processing them into yarn, forming from a yarn a knitted fabric and composite material in the form of a package of knitted disks, followed by high-temperature processing of the composite material.

However, this method has the following disadvantages:

upon receipt of yarn, the classic multi-junction method of yarn is used with the obligatory operation of preliminary sizing of the thermostabilized PAN bundle, since in the absence of sizing of the bundle, the stapled tape is not connected between the individual fibers and on the technological transitions of the classical method of yarn (carding, tape and roving transitions) shedding of staples and violation of the integrity of the tape are observed, i.e. the technological capabilities of this method are not high;

the method of yarn yarn production including turning on yields yields a limited variety of yarns - linear density yarn 176 tex (88 tex x 2). Data on the possibility of yarns of lower linearity of density (finer yarn) and, therefore, of higher quality by this technology are not given.

The aim of the invention is to improve the quality of the filler and expand its range and technological capabilities of the method.

X8 x | YU

YU

This is achieved in that in a method for producing a carbon textile filler of a composite material, which consists in thermostabilization of an initial polyacrylonitrile tow in an oxygen-containing medium, their stapling, the formation of yarn from stapled fibers and the formation of a textile web from yarn, followed by its high-temperature inert processing , as a source tow, a tow of linear density 850-13300 tex is used, the tow is thermally stabilized until its density is 1350-1 380 kg / m3, and the formation of yarn from stale fiber fibers is carried out on a rotor spinning machine immediately after the stapling of the strands.

When the PAN fiber is thermally stabilized, the linear structure of the PAN is transformed into a cyclic one, which is characteristic of the thermostabilized PAN. In this case, the pycnometric density of the material varies from 1200 kg / m3 (for the initial PAN fiber) to 1400-1450 kg / m3 (for the fiber that has undergone a complete thermal stabilization process). This process is accompanied by a decrease in physicomechanical properties (breaking load, elongation, elastic properties characteristic of the initial PAN fiber) and, naturally, the textile processing ability is deteriorated.

The need to obtain a thermostabilized PAN tow with a pycnometric density of 1350-1380 kg / m is due to the following:

- undeoxidized PAN bundle (pycnometric density below 1350 kg / m3) is perfectly processed into yarn, since the fiber still has sufficiently high elastic properties, due to the fact that the cyclic fragments did not form in the entire volume of the fiber and partially retained linear polymer structure. From such yarn it is possible to obtain a fabric with high physical and mechanical characteristics, but with subsequent high-temperature processing of 1400-2000 ° C, it burns up, since the necessary fiber structure is not obtained, able to withstand high temperature (Example 4 of the table);

-PAN harness with a pycnometric density higher than 1380 kg / m3, which is characterized by the presence of a large number of cyclic fragments (as confirmed by the electron paramagnetic resonance method), has increased stiffness and brittleness and low tensile characteristics. Processing in

the yarn is difficult, and the obtained yarn samples have low strength properties, which makes it impossible to process it into textile structures (example

5 tab.).

The range of the pycnometric density of the thermostabilized PAN tow of 1350-1380 kg / m3, providing the possibility of obtaining high-quality yarn,

0 suitable for further textile processing on standard textile equipment, and allowing subsequent high-temperature processing of textile filler,

5 experimentally.

At the same time, the technological capabilities of the method are expanded — the sufficiently high elastic properties of the thermostabilized tow allow to process yarn obtained from it on automated weaving and knitting machines, producing fillers in a wide assortment (fabrics of various weaving and knitwear of various structures with different thicknesses5 are not filler, if to use yarn of different linear density in its manufacture: 50 tex (25 tex x 2) and higher.

The proposed method for producing a carbon textile filler uses yarn obtained by the pneumomechanical (single junction) method of spinning. The single-junction method allows the production of yarn from fibers characterized by increased fragility and electrification.

5 without additional treatment with sizing components, and poorly withstanding the numerous technological transitions characteristic of traditional, classic spinning systems. Turning

0 thermostabilized PAN bundle in yarn is carried out by stapling with non-simultaneous rupture of elementary fibers of the bundle due to ultra-high stretching with the creation of a discrete stream of fibers

5 and forming a yarn therefrom using a pneumomechanical spinning chamber. The staple device and the pneumomechanical spinning chamber are combined into one unit.

Using the pneumomechanical spinning method yields a yarn characterized by a core with a lower fiber packing density and an entwining layer with a greater number of fibers than the ring spinning yarn. As a result, the fiber straightness coefficient decreases and the hairiness of the yarn increases.

The use of such yarn allows to reduce the mass of the filler, its thickness,

increase stiffness, which reduces air permeability while maintaining mainly physical and mechanical properties. This contributes to improving the quality of the textile filler and expanding the scope of its use.

To produce yarn, PAN of a bundle density of 850-13300 tex was used as raw material. A tow with a linear density below 850 tex is inappropriate to use from the point of view of the economy of production. It is also impractical for a specific pneumomechanical method to use as a raw material PAN tourniquet of a higher (determined) linear density, since it will have significant non-uniformity of physicomechanical parameters, which is due to the uneven heating of the thick tourniquet at the stage of thermal stabilization. The properties of the yarn and, accordingly, the textile filler are directly dependent on the physicomechanical parameters of the thermostabilized PAN tow.

Example. A PAN tow of linear density 850 tex (TU 6-12-5757604-9-89) is thermally stabilized in an oxygen-containing atmosphere at a temperature of 220 ° C until a pycnometric fiber density of 1370 is obtained. The tourniquet is processed into a single yarn of linear density 25 tex and more in a pneumomechanical way. To balance the structure, a single yarn is folded in two ends when twisted together in the opposite direction to the initial twist, until a yarn of linear density of 50 tex or more is obtained. Physico-mechanical indicators are given in the table. The weave fabric is made from yarn and subjected to high-temperature processing at temperatures above 2000 ° C in an inert atmosphere. Physico-mechanical properties of the tissue are shown in the table, example 1.

The table of Examples 2, 3, 6 shows the properties of yarns and textile fillers (fabrics of various weaving, knitwear) obtained from PAN of heat-stabilized tows based on feedstock of different linear densities from 1700 to 13300 tex. Data on the influence of the degree of thermal stabilization of PAN fiber (different pycnometric densities of 1330 kg / m3 and 1410 kg / m3) on the possibility of yarns and textile fillers - examples 4 and 5 are described above.

An analysis of the data in the table shows that the use of a thermostabilized PAN tow when yarn is prepared with a pycnometric fiber density lower or higher than those stated in the formula does not allow obtaining a carbon fiber filler.

Using the proposed method allows to improve the quality of the textile filler (to reduce the thickness and weight of the filler), to expand the range by varying the thickness of the filler, the type of weave and structure, respectively, for woven and knitted fillers; expand the technological capabilities of the method.

Claims (1)

The claims A method for producing a carbon textile filler of a composite material, which consists in thermostabilization of an initial tow of polyacrylonitrile filaments in an oxygen-containing medium, their stapling, the formation of yarn from stapled fibers and the formation of a textile web from yarn, followed by its high-temperature processing in an inert medium, characterized in that , in order to improve the quality of the filler and expand its assortment and technological capabilities of the method, using a strand of linear density 850–13300 tex is pressed, the tow is thermally stabilized until its density is 1350–1380 kg / m, and yarn is formed from stapled fibers on a rotor spinning machine and immediately after stapling the strands. I is the tensile strength in bending of a thread about plastic, EY is the elastic modulus in bending of a thread in plastic; Er is the tensile strength; The filler is obtained on an automated machine.