WO2024005669A1

WO2024005669A1 - Electrically conductive composite fibre and method for producing and using same

Info

Publication number: WO2024005669A1
Application number: PCT/RU2023/050085
Authority: WO
Inventors: Ольга Андреевна МОСКАЛЮК; Сергей Олегович КИРИЧЕНКО; Владимир Евгеньевич ЮДИН; Екатерина Сергеевна ЦОБКАЛЛО; Павел Викторович ПОГРЕБНЯКОВ; Алексей Николаевич ГОЛДАЕВ
Original assignee: Общество С Ограниченной Ответственностью "Ампертекс"
Priority date: 2022-06-27
Filing date: 2023-04-12
Publication date: 2024-01-04

Abstract

Proposed is an electrically conductive composite fibre that contains a matrix consisting of a fibre-forming thermoplastic polymer, and an electrically conductive filler dispersed in said matrix, wherein the electrically conductive filler is a mixture of carbon black nanoparticles and carbon nanotubes in a ratio of from 4:1 to 12:1. Also proposed is a method for producing the electrically conductive fibre according to the invention and for using said fibre to manufacture flexible textile articles for use in heating, as well as textile articles that dissipate static charge.

Description

ELECTRICALLY CONDUCTIVE COMPOSITE FIBER AND METHOD OF ITS PRODUCTION AND APPLICATION

TECHNICAL FIELD

The present invention relates to the field of electrically conductive polymer composite materials, in particular electrically conductive composite fibers and threads, and flexible heating and antistatic products thereof, such as flexible heating fabrics and meshes suitable for use in heating systems, as well as smart textiles thereon. basis.

BACKGROUND OF THE ART

Electrically conductive polymer materials (ECMs) are composite materials based on a polymer matrix and an electrically conductive filler. They are widely used in the manufacture of heating and antistatic products, electromagnetic protective coatings, conductive adhesives and varnishes, etc. Among EPMs, electrically conductive composite fibers and threads are of particular interest, which have great potential for use in the field of “smart” textiles, allowing the integration of intelligent electronic devices into textiles through a combination of different technologies and materials. It is expected that in the near future, conductive fibers will play an important role in many key areas, including the transmission of electrical current and information. Therefore, the creation of affordable flexible and wear-resistant electrically conductive fibers can be considered as a first and highly relevant step for the future production of smart fabrics for a wide range of applications.

Developments in the field of creating electrically conductive composite fibers (ECF) have been ongoing for several decades. One of the known approaches is to create EVCs having a core-shell structure, where the conductive material is deposited as a shell on a polymer fiber. Such a solution is proposed, for example, in RF patent No. 2001164, which describes an electrically conductive thread containing a core in the form of a filament thread made of polycaproamide or polyethylene terephthalate, and a shell made of fluorine-containing polymer with the addition of 5-15% highly dispersed metal powder. This technology for producing ECI, however, has a number of significant limitations, the main of which are the adhesion interaction at the core-shell layer boundary and the low production speed compared to the extrusion method.

Another approach is to disperse particles of electrically conductive filler in a matrix of polymer material, which makes it possible to obtain an EVC with uniform electrical resistance along the entire length and simplify the technology for manufacturing the EVC. This approach is implemented, for example, in RF patent No. 2203352, where an electrically conductive resistive thread for woven heating elements is proposed, consisting of synthetic fiber based on poly-t-phenylene isophthalamide, poly-p-phenylene terephthalamide or poly-p-benzamide and carbon dioxide dispersed in it filler, which is a mixture of carbon black and graphite. Such a resistive thread is characterized by increased stability of linear electrical resistance along the length of the thread, high strength and rigidity, and an extended operating temperature range with an upper limit of 250-350 °C. The disadvantages of this technology are the relatively high cost of the polymers used and the low elongation of the thread at break, due to the physical and mechanical characteristics and the spherical shape of the carbon filler particles, leading to fragility of the resulting composite thread when exposed to increased mechanical loads, which arise, for example, when repeatedly bending or washing textiles. products made using such thread.

To create flexible ECFs, it was proposed to use an extended filler dispersed in a polymer matrix. For example, RF patent No. 2585667 proposes a method for producing antistatic polypropylene fiber with improved mechanical properties, where carbon nanotubes or carbon nanofibers are used as an electrically conductive filler. Such ECFs are characterized by good plastic properties, but at the same time insufficiently good conductive properties, which does not allow their use in textiles with high requirements for fiber conductivity, such as heating fabrics and “smart” textiles, and, at the same time, increased requirements for the plastic characteristics of the fiber .

Accordingly, there continues to be a need in the art to provide a flexible and wear-resistant electrically conductive filament with good conductivity properties that can be produced in a simple and economical manner from high-volume polymers. DISCLOSURE OF INVENTION

In the present invention, this problem is solved by creating an electrically conductive composite fiber containing a matrix of fiber-forming thermoplastic polymer and an electrically conductive filler dispersed in the specified matrix, where the electrically conductive filler is a mixture of carbon black nanoparticles and carbon nanotubes in a ratio of 4:1 to 12:1. The use of a mixture of carbon black nanoparticles and carbon nanotubes in the specified ratios as an electrically conductive filler makes it possible to obtain an electrically conductive fiber with good conductivity and low linear density, which at the same time has high physical and mechanical characteristics, such as specific breaking load and elongation at break. The proposed fiber can be produced on an industrial scale by melt extrusion using inexpensive large-scale polymers and used for the production of flexible heating textiles and smart textiles with high wear resistance.

BRIEF DESCRIPTION OF GRAPHIC MATERIALS

In FIG. 1 is a general diagram of the technological process for producing an electrically conductive composite fiber according to the present invention, which shows:

1 - twin-screw extruder;

2 (optional) - bath for cooling the fibers;

3 - belt conveyor;

4 - rollers;

5 - exhaust chamber with several heating zones;

6 - receiving device.

IMPLEMENTATION OF THE INVENTION

According to a first aspect, the present invention provides an electrically conductive composite fiber comprising a matrix of fiber-forming thermoplastic polymer and an electrically conductive filler dispersed in said matrix, wherein the electrically conductive filler is a mixture of carbon black nanoparticles and carbon nanotubes in a ratio of 4:1 to 12:1. In the course of extensive research work, the authors of the present invention unexpectedly discovered that the use of a mixture of carbon black nanoparticles and carbon nanotubes in the indicated ratios as an electrically conductive filler makes it possible to obtain an electrically conductive fiber with good conductivity and low linear density, which also has good physical and mechanical characteristics, such as specific breaking load and elongation at break. Without wishing to be bound by any particular theory, the inventors believe that the resulting improved fiber properties in the form of good conductive properties and, at the same time, good strength and ductility are achieved due to the specific interaction of anisometric carbon nanotubes and spherical carbon black nanoparticles, which leads to an increase in the number of contacts in a carbon filler, ensuring good conductivity even after repeated orientation drawing of the fiber. At the same time, the use of carbon nanotubes in the composition of the combined carbon filler in an amount of up to 3% by weight makes it possible to give the electrically conductive fiber the necessary flexibility and elasticity, and the use of carbon black nanoparticles in specified ratios provides the required deformation-strength properties of the composite fiber and reduces the cost of the material. Due to this, the electrically conductive fiber according to the invention is resistant to increased mechanical stress, which occurs, for example, during repeated folding or washing of a textile product made using such fiber, and is at the same time suitable for use in textile products with high requirements for the conductivity of the fiber.

For purposes of the present invention, the thermoplastic polymer can be any thermoplastic polymer suitable for use in the field of making electrically conductive composite fibers. In one preferred embodiment, the thermoplastic polymer may be selected from the group consisting of polyolefin, polyamide, polyester, polyacrylonitrile, polyvinyl alcohol. In a more preferred embodiment, the thermoplastic polymer may be polyethylene or polypropylene.

Likewise, carbon black may be any variety of carbon black suitable for use in ECR, including, but not limited to, highly structured highly conductive carbon black, carbon black derived from acetylene, natural gases, furnace, channel, thermal carbon black, and others. For purposes of the present invention, the carbon nanotubes may be any commercially available single-walled or multi-walled carbon nanotubes, including, but not limited to, CTube-100 grade multi-walled carbon nanotubes, SWCNT-60 single-walled carbon nanotubes, etc. In one preferred embodiment, the carbon nanotubes are single-walled carbon nanotubes. According to another preferred embodiment, carbon nanotubes have a length:diameter ratio of 60 to 3500.

In the proposed ECFs, the total content of electrically conductive carbon filler ranges from 9 to 13% by weight, based on the weight of the fiber-forming thermoplastic polymer. According to particular embodiments of the invention, the content of electrically conductive carbon filler in EKV can be 9, 10, 11, 12 or 13% by weight, based on the weight of the fiber-forming thermoplastic polymer.

In the present invention, the electrically conductive filler is a mixture of carbon black nanoparticles and carbon nanotubes in a ratio of 4:1 to 12:1. According to particular embodiments of the invention, the ratio of carbon black nanoparticles and carbon nanotubes in the electrically conductive filler can be 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1 or 12 :1.

In one of the preferred embodiments of the ECR, the content of carbon nanotubes is from 0.5 to 3% by weight, based on the weight of the fiber-forming thermoplastic polymer. In a more preferred embodiment, the carbon nanotube content is up to 2% by weight, most preferably 2% by weight, of the fiber-forming thermoplastic polymer. In other preferred embodiments, the carbon nanotube content is 0.5 to 1 wt%, 1 to 2 wt%, or 2 to 3 wt% of the fiber-forming thermoplastic polymer. In specific embodiments, the carbon nanotube content is 0.5, 1, 1.5, 2, 2.5, or 3 weight percent of the fiber-forming thermoplastic polymer. In general, the content of carbon nanotubes in ECF according to the invention does not exceed 3 wt% of the mass of the fiber-forming thermoplastic polymer, since when the content of carbon nanotubes exceeds 3 wt%, embrittlement of the ECF occurs. In this case, the content of carbon nanotubes must be at least 0.5% by weight of the mass of the fiber-forming thermoplastic polymer, since at lower contents the required electrical conductivity characteristics of ECV are not achieved. In one preferred embodiment, the ECI according to the present invention is an electrically conductive composite thread. According to one particular embodiment of the invention, said thread may be a twisted thread.

According to one embodiment, the electrical resistance of the ECR ranges from 20 kOhm to 150 kOhm per linear meter of fiber. According to a particular embodiment, the electrical resistance of the ECR ranges from 80 kOhm to 120 kOhm per linear meter of fiber.

According to one embodiment, the elongation at break of the fiber is at least 10%, for example, but not limited to, 10-25%, 10-13%, 15-20%, etc.

According to a further aspect, the present invention also provides an electrically conductive textile fabric containing an electrically conductive composite fiber according to the invention. According to a preferred embodiment, the electrically conductive textile fabric according to the invention is a fabric or mesh. The warp of the fabric or mesh is made of ordinary synthetic fibers, and the weft is made of ECF according to the present invention. With a certain step, tinsel threads are woven into the fabric, acting as electrodes. When electric current is applied to the fabric, heating occurs, and by adjusting the weaving step of electrically conductive threads and electrodes, you can regulate both the heating temperature and the power source from which the heating is carried out (5V, 12V, 24V, 36V and 220V). Such fabrics and meshes can be bonded to any surface such as other fabric, leather, rubber, ceramics, paper, chipboard, etc. to create a heating system suitable for any surface.

In another aspect, the present invention provides the use of the electrically conductive composite fiber of the invention for the manufacture of flexible heating textiles, including, but not limited to, heating pads, rugs, mats, blankets, blankets, sheets, sleeping bags, heated clothing, and the like.

In yet another aspect, the present invention provides the use of the electrically conductive composite fiber of the invention for the manufacture of static dissipative textile products, including, but not limited to, workwear, antistatic cleaning textiles, antistatic textile wall coverings, and the like. According to a further aspect, the present invention provides a method for producing an electrically conductive composite fiber according to the invention, comprising the steps of:

(a) mixing in an extruder a melt of the fiber-forming thermoplastic polymer with the electrically conductive filler, causing the electrically conductive filler to be dispersed in the fiber-forming thermoplastic polymer,

(b) extruding fiber from this mixture, and

(c) high-temperature orientation drawing of the resulting extruded fiber, wherein said electrically conductive filler is a mixture of carbon black nanoparticles and carbon nanotubes in a ratio of 4:1 to 12:1.

According to one preferred embodiment, the melt temperature in step (a) is between 180 and 220 °C. According to another preferred embodiment, the melt temperature in step (a) is between 200 and 210 °C. In specific embodiments, the melt temperature in step (a) is 180, 190, 200, 210, or 220 °C.

According to another preferred embodiment, the orientation drawing in step (c) is carried out at a temperature of 130 to 140 °C. According to another preferred embodiment, the orientation drawing in step (c) is carried out 4 to 8 times, for example 4.5 to 5.5 times, in particular 4.5, 5, 5.5, 6, 6.5, 7, 7.5 or 8 times. In one particular embodiment, the orientation drawing in step (c) is carried out in one step. In one particular embodiment, the fiber(s) are cooled in a bath of water prior to orientation drawing.

The present invention is further illustrated by the following non-limiting examples of its implementation.

EXAMPLES

Preparation of electrically conductive composite fiber according to the invention

Example 1

The composite fiber was produced in accordance with the general process flow diagram shown in FIG. 1 (positions 1-3). Polypropylene granules were fed into the chamber of a twin-screw extruder, heated to 210-215°C, through the main feeder at a flow rate of 400-500 g/h and melted to a viscous-flowing state. After the free flow of the polymer from the die, 1 wt% carbon nanotube concentrate based on the mass of the final composite was fed through the first side feeder. After the black color of the flowing polymer appeared, the supply of carbon nanotube concentrate was increased to 2 wt.% and 10 wt.% of carbon black was fed through the second side feeder based on the mass of the final composite. The total mass flow of polypropylene and fillers was set to 750-850 g/h, and the pressure was adjusted to -0.5 bar using a vacuum pump. After stabilizing the pressure in front of the die at a level of 55-60 bar, the conveyor was started at a linear speed of 10-12 m/min. The fibers (filaments) coming out of the spinneret were put onto a conveyor and cooled on the conveyor belt with a stream of air at room temperature, after which they were fed to the first group of receiving rollers with a diameter of 20 cm each and passed through a tunnel oven heated to 130-140 ° C, and then passed through a second group of receiving rollers with a diameter of 20 cm each. During passage through the tunnel oven, the filaments passed into an oriented state with a thinning cross section. The drawing speed was selected in such a way that the filaments completely transferred to the oriented state and did not contain unstretched sections of the original cross section. The drawing was carried out in one stage, and the drawing ratio was 4-6 times, depending on the required parameters of the final fiber. The oriented filaments were then fed to a winder and wound onto a bobbin with an internal diameter of 75 mm in a cross winding pattern.

Example 2

The composite fiber was prepared in accordance with the general procedure according to Example 1 with the difference that the total mass flow rate of polypropylene and fillers was set equal to 700 g/h, while the consumption of carbon nanotubes was set based on the carbon nanotube content in the final ECF equal to 0.9 wt%. ., and the carbon black consumption was set based on the carbon black content in the final EQU equal to 11 wt%.

Determination of physical and mechanical properties of electrically conductive composite fiber according to the invention

Example 3 In accordance with the method described in Examples 1 and 2, six samples (samples 1-6) of composite fiber with different linear densities (from 42 to 64 tex) were manufactured, the characteristics of which are shown below in Table 1. During the tests, the linear density was determined , specific breaking load, elongation at break and specific linear electrical resistance of the samples.

The linear density of threads was determined in accordance with GOST 6611.1-73 (ISO 2060-72) Textile threads. Method for determining linear density. Linear density was measured on a fiber 1 m long using a laboratory electronic balance LV 120-A, accuracy class I, resolution 0.1 mg.

Tests by uniaxial tension of the obtained samples of composite threads according to the invention (samples 1-6) and control samples - fibers based on electrically conductive filler carbon black: graphite according to RU 2203352 (comparison samples 1-2 (Cf. 1-2 in Table 1)) and polypropylene fibers filled with carbon nanotubes in accordance with RU 2585667 (comparison samples 3-4 (Cf. 3-4 in Table 1)) - were carried out using an Instron universal testing machine according to the GOST 6611.2-73 textile threads method. Methods for determining breaking load and elongation at break. The clamping length was 250 ± 1 mm, and the stretching speed was selected so that the average duration of the fiber stretching process before breaking was 20 ± 3 s. Based on the obtained tensile diagrams, the values of elongation at break E, % and specific breaking load Ru, cN/tex were determined (Table 1).

Measurement of electrical resistance and electrical impedance of samples of composite fibers according to the invention (samples 1-6) and control samples (samples Comp. 1-2 in Table 1) was performed on a Solartron 1260 impedance meter with a Solartron 1287 potentiostat-galvanostat.

The images were secured on a tripod vertically in a tense state using Hirschmann AGF20 crocodile connectors with low contact resistance. The connection of the measuring connectors was made according to the pseudo-Kelvin 4-2 scheme with the separation of power and measuring conductors directly at the connector. Direct current resistance measurements were carried out in the potential range of 0.13.0 V with a step of 0.1 V for 10 seconds per point with further averaging over all measured values and calculation of the resistivity per linear meter of the sample. Impedance measurements were carried out at frequencies of 50 Hz, 1 kHz, 10 kHz, 100 kHz and 1 MHz by applying a measuring signal with an amplitude of 100 mV for 10 seconds. Previously The test bench was calibrated in short-circuit mode and measuring a reference graphite block resistor of 100,000 ohms. Corrections for contact resistance obtained during this calibration were taken into account in the sample measurements. Before carrying out measurements, samples 520 mm long were cut out of filaments and fibers according to a template, wiped with a lint-free cloth with isopropanol, then Auromal 35 silver paste was applied to each side of the sample at a distance of 10 mm (including the ends). Next, the samples were clamped into connectors so that inside each there was an area with the applied paste, the temperature and humidity of the air were measured and measurements were taken.

The test results are shown below in Table 1.

Table 1 - Values of physical and mechanical parameters of fiber

As can be seen from the data in Table 1, the composite fibers according to the invention have comparable conductivity compared to control samples based on electrically conductive filler carbon black: graphite, while having significantly improved elongation at break, and significantly improved conductivity compared to control samples based on electrically conductive filler filler made of pure carbon nanotubes, while possessing comparable deformation-strength properties, which allows the use of EKV according to invention for the manufacture of flexible heating textiles with increased resistance to washing and abrasion.

AND

Claims

CLAIM

1. An electrically conductive composite fiber containing a matrix of fiber-forming thermoplastic polymer and an electrically conductive filler dispersed in said matrix, wherein said electrically conductive filler is a mixture of carbon black nanoparticles and carbon nanotubes in a mass ratio of 4:1 to 12:1, while said electrically conductive composite fiber is characterized by an elongation at break of at least 10%.

2. Electrically conductive composite fiber according to claim 1, characterized in that the fiber-forming thermoplastic polymer is selected from the group including polyolefin, polyamide, polyester, polyacrylonitrile, polyvinyl alcohol.

3. Electrically conductive composite fiber according to claim 2, characterized in that said polyolefin is polyethylene or polypropylene.

4. Electrically conductive composite fiber according to any one of paragraphs. 1-3, characterized in that carbon black is a highly structured, highly conductive carbon black, carbon black obtained from acetylene, natural gases, furnace, channel, thermal carbon black.

5. Electrically conductive composite fiber according to any one of paragraphs. 1-4, characterized in that these carbon nanotubes are characterized by a length: diameter ratio from 60 to 3500.

6. Electrically conductive composite fiber according to any one of paragraphs. 1-5, characterized in that said carbon nanotubes are single-walled carbon nanotubes.

7. Electrically conductive composite fiber according to any one of paragraphs. 1-6, characterized in that the content of the electrically conductive filler is from 9 to 13% by weight, based on the weight of the fiber-forming thermoplastic polymer.

8. Electrically conductive composite fiber according to any one of paragraphs. 1-7, characterized in that the content of carbon nanotubes is from 0.5 to 3% by weight, based on the weight of the fiber-forming thermoplastic polymer.

9. Electrically conductive composite fiber according to any one of paragraphs. 1-8, characterized in that said fiber is a thread.

10. Electrically conductive composite fiber according to any one of claims. 1-9, characterized in that the electrical resistance of said fiber ranges from 20 kOhm to 150 kOhm per linear meter of fiber.

11. An electrically conductive textile fabric containing an electrically conductive composite fiber according to any one of claims. 1 -10.

12. Electrically conductive textile fabric according to claim 11, which is a fabric or mesh.

13. The use of electrically conductive composite fiber according to any one of paragraphs. 1 -10 for the production of flexible heating textiles.

14. The use of electrically conductive composite fiber according to any one of paragraphs. 1 -10 for the manufacture of textiles that dissipate static charge.

15. A method for producing electrically conductive composite fiber according to any one of claims. 1 -10, including stages:

(a) mixing in an extruder a melt of the fiber-forming thermoplastic polymer with the electrically conductive filler to ensure that the electrically conductive filler is dispersed in the fiber-forming thermoplastic polymer,

(b) extruding fiber from this mixture, and

16. Method according to claim 15, characterized in that the melt temperature at stage (a) is from 180 to 220 °C.

17. The method according to claim 15 or claim 16, characterized in that orientation drawing at stage (c) is carried out at a temperature of 130 to 140 °C.

18. Method according to any one of paragraphs. 15-17, characterized in that orientation stretching at stage (c) is carried out from 4 to 8 times.

19. Method according to any one of paragraphs. 15-18, characterized in that said extruder is a twin-screw extruder.

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