KR101736080B1 - Process Of Producing Electroconductive Bicomponent Fiber - Google Patents

Abstract

The present invention relates to a method for producing an electroconductive composite fiber having electroconductive properties at the similar level with a conductor through a spinning process. According to the present invention, an electroconductive composite fiber has excellent conductivity of 200 /cm or less and physical properties of 80 MPa or more without problems in a sinning process. Therefore, provided is a metal nanoparticle-carbon nanotube-alginate conductive composite fiber which can be applied for textile products based on wearable devices, can be applied in biomedical fields such as a bioactuator, a biosensor, etc. for artificial muscle due to excellent biocompatibility, discharges few harmful materials in a spinning process and has excellent process properties.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electroconductive composite fiber,

The present invention relates to a method for producing electrically conductive fibers having conductor-level electrical conductivity properties by a spinning process.

Generally, electrically conductive fibers (hereinafter referred to as conductive fibers) refer to fibrous materials that can contain a material that can electrically conduct electricity to the fiber itself or an internal structure thereof, and can flow a certain amount of electricity.

The method of manufacturing such fibers can be classified into a method of using a conductive polymer and a method of combining a conductive material. To date, a fiber produced by an electron technology has a good conductivity over a semiconductor level, It is difficult to use for product use. In addition, the conductivity is not good enough to be used for sensor applications and further for electric leads.

In the latter case, more specifically, the conductive additive material may be incorporated into the fiber to produce a fiber, or the plating method may be used to coat the fiber with a common fiber. The conductive composite fiber prepared by mixing with the fiber polymer is excellent in durability and it is possible to realize various physical properties and conductivity depending on the conductive additive material and the matrix polymer to be used, but the conductive level conductive material 10 ² S / Cm However, on the other hand, conductive fiber production by post-treatment coating has been tried variously due to its low technical difficulty. However, it is difficult to achieve the desired effect of coating by fiber coating There is a problem of deterioration and durability deterioration.

The most recently developed conductive composite fibers can be divided into melt-radial conductive composite fibers and wet-radial conductive composite fibers according to a specific manufacturing method, and the matrix fiber polymer of the melt-radial conductive composite fibers is made of polyester, nylon, poly Propylene, and polyethylene. Matrix fiber polymers of the wet-type radial conductive composite fiber include synthetic polymers such as polyacrylonitrile, polyurethane, and polyvinyl alcohol, and recycled polymers such as viscose rayon and lyocell. Cellulose, and polysaccharide polymer fibers such as chitin / chitosan and alginate.

As a method for producing conductive fibers using the most common thermoplastic fiber polymer, a master batch having a concentration of several tens% by weight is prepared by a conductive additive material such as a metal powder, a carbon nanotube, and a graphene, Melt spinning to produce conductive fibers. The conductive fibers thus produced usually exhibit a conductivity of about 10 ⁰ S / cm (single-digit) on the order of a semiconductor, which is a technical limitation to the present. Raising the content of the conductive additive for the further development of conductivity requires a high melting point It is very difficult to change the properties of the additive material due to degradation, high temperature and shear force.

The production of conductive fibers by wet spinning can incorporate a relatively high proportion of the conductive additive as compared to the spinneret method by incorporating the additive at a relatively low viscosity and by maintaining the relatively low viscosity and process temperature, It is possible to maintain the electric conduction characteristic by minimizing the chemical form change. However, most of these wet spinning processes require strong acids, strong bases, and organic solvents such as dimethylformamide and dimethylacetamide. In addition, the conductivity of the manufactured fibers has not reached the level of 10 ² S / cm to date. In order to overcome these disadvantages, studies on the fabrication of fibers composed of conductive materials alone are underway.

For example, Korean Patent Laid-Open Publication No. 10-2012-0107026 discloses a method for producing graphene fibers by dispersing graphene in a surfactant, mixing the polymer with a polymer, wet-spinning the polymer, and then removing the polymer through heat treatment or acid treatment . In addition, some researchers fabricated carbon nanotube fibers by dispersing carbon nanotubes in super strong acids such as concentrated sulfuric acid and chlorosulfonic acid, and then wet-spinning them (11 JANUARY 2013 VOL 339 SCIENCE). The conductive fibers thus produced exhibit very good electrical conductivity at the conductor level. However, there are many problems to be solved for general fiber use because of the limitations of the process of using super strong acid and the very low flexibility of the fiber composed of the carbon isotope alone. Although a variety of conductive fibers are being developed for the coming era of smart apparel, there is a need to develop conductive fibers that are more conductive than semiconductors, capable of applying strength and flexibility to general textile products, R & D is more demanded. Therefore, it is required to develop a conductive fiber of a wet spinning method utilizing a polysaccharide polymer having excellent physical properties while allowing a large amount of conductive additive to be mixed and radiated, and there is little discharge of toxic substances in the process.

Korean Patent Laid-Open Publication No. 10-2012-0107026 (published on September 28, 2012) Korean Patent Laid-Open Publication No. 10-2014-0071751 (published on June 12, 2014)

Accordingly, it is a technical object of the present invention to provide a method for producing a conductive fiber having superior electrical conductivity exceeding a semiconductor level, strength, elongation and flexibility suitable for use in a textile product, . Another object of the present invention is to provide a method for manufacturing a conductive fiber for a biomedical system which can be used as a biosensor or a bio-cell electrode by using a biomolecule excellent in biocompatibility as an instrument.

Therefore, according to the present invention, 10 to 80% by weight of metal nanoparticles, 1 to 20% by weight of multi-walled carbon nanotubes, and distilled water as a remainder are mixed and stirred in a bath at 40 to 60 ° C for 2 to 3 hours with ultrasonic waves, After making the nanoparticle-carbon nanotube aqueous dispersion,

The metal nanoparticle-carbon nanotube aqueous dispersion was mixed with 5-15 parts by weight of sodium alginic acid polymer with respect to 100 parts by weight of the metal nanoparticle-carbon nanotube aqueous dispersion, and the mixture was stirred while applying ultrasonic waves to prepare a metal nanoparticle-carbon nanotube / alginate spinning solution , ≪ / RTI >

The water is degassed to remove air bubbles, filtered and then discharged in a fixed quantity through a gear pump to solidify in a coagulating solution of calcium chloride, followed by drying in an aqueous acid bath for water treatment, oil production and acid treatment, A method for producing a conductive composite fiber is provided.

Hereinafter, the present invention will be described in more detail.

The method for producing an electrically conductive composite fiber according to the present invention is a method of wet spinning by mixing an aqueous dispersion in which metal nanoparticles-carbon nanotubes are dispersed in distilled water and an aqueous alginate solution. More specifically, it is preferable that the conductive material is mixed with the conductive additive material during the wet spinning process, and the electrical conductivity is higher than that of the conventional conductive fiber, and the physical properties such as the strength and elongation are obtained from the electroconductive fibers suitable for producing the two- or three- And a manufacturing method thereof.

In the present invention, alginic acid used as a material for conductive fibers is extracted from brown algae, which is one of marine organisms. Since the carboxyl group (COOH-) of uronic acid is present in the molecule, it exhibits properties of acid, usually sodium salt. Sodium alginate is known to be readily fibrous by spinning calcium chloride solution into a coagulating bath ( Encyclopedia of textile finishing, HK Rouette, Springer, 2000 ). It is used in foods, medicines and textile industry because it is non-toxic to human body, easy to process, soluble in water and exhibits high viscosity, and forms a cross-link with metal salt to induce gel. ) With chitin, chitosan and other natural polymers.

The chemical structure of alginic acid is as shown in the following formula (1), as a block copolymer of maleuronic acid (M) unit, a block of glutaric acid (G) unit and a block of MG unit in the middle thereof as a linear chain composed of 1,4- Physico - chemical properties are known to be influenced by physical properties such as viscosity, solubility, and ion exchange capacity due to differences in M / G ratio, molecular arrangement, and molecular weight.

[Chemical Formula 1]

The alginate in which the carboxyl group of the alginic acid is prepared in the form of a sodium salt (-COO ^- Na ⁺ ) is called an alginate. The alginate has a characteristic of a polyelectrolyte and thus has favorable conditions for the production of a conductive fiber.

Carbon nanotubes used as conductive additive materials in the present invention were first discovered in 1985 by Kroto and Smalley as fullerenes (carbon atoms 60 carbon atoms: C ₆₀ ), one of carbon allotrope, IJima of Japan Electricity Company (NEC), who was working on the research, was found in the process of TEM analysis of the carbon particles formed on the graphite cathode using the electric discharge method. Since then, research on various physical and chemical properties has been carried out. In particular, due to excellent electrical conductivity and excellent physical properties close to the metal level, various conductive materials such as display, touch panel and conductive fiber It is getting popular as an implementation material. However, when a small size of nanometer size (diameter: single-walled carbon nanotube <2 nm, multi-walled carbon nanotube 5 to 100 nm) causes flocculation due to van der Waals attraction and is used as an additive for conductive fibers, Technology is essential.

Since alginate, which is a biopolymer used in the present invention, is required to design a carbon nanotube as a water-soluble polymer and also to design a water dispersion system, in the present invention, carbon nanotubes are dispersed first, and then a post- Go ahead.

In the present invention, 10 to 80% by weight of metal nanoparticles, 1 to 20% by weight of multi-walled carbon nanotubes, and distilled water as a remainder are mixed and stirred in a bath at 40 to 60 ° C for 2 to 3 hours with ultrasonic waves, After the carbon nanotube aqueous dispersion was prepared, 5 to 15 parts by weight of sodium alginic acid polymer was mixed with the metal nanoparticle-carbon nanotube aqueous dispersion in an amount of 100 parts by weight of the metal nanoparticle-carbon nanotube water dispersion, and the mixture was stirred with ultrasonic waves, Particle-carbon nanotube / alginate spinning solution.

The molecular weight of the alginic acid is preferably from 30 to 500,000, and the polydispersity index is preferably less than 2.5. The isomer composition ratio of mannuronic acid to gluronic acid (M / G ratio) is 0.6 to 1.4 And 0.6 to 1 (G > M) is preferable for the conductive fiber application. Although alginic acid is a linear polymer composed of M block and G block two components, it is biosynthesized from natural products, so that the composition ratio and arrangement order are irregular according to the raw material. Also, according to the ratio of M block, G block and M / . As for the binding property with metal ion, G block has a property of binding metal ion in the form of "egg box", M block has a structure like cellulose and merely carries ionic bond with carboxy group so that glutaric acid The more it is, the more advantageous it is to produce conductive fibers.

The viscosity of the spinning stock solution is 50,000 to 200,000 cps and the concentration is 5 to 15 wt%, preferably 8 to 10 wt%. The prepared spinning liquid is filtered through insulated powder and impurities through a mesh filter, then defoamed under reduced pressure, passed through a gear pump for quantitative discharge through air pressure, and discharged through a spinneret. After that, a gel-like fiber is formed by a sodium-calcium ion exchange reaction in a calcium chloride coagulating solution, and washed and dried to produce a fiber. The above process is similar to a conventional alginic acid fiber production process. In order to produce the conductive fiber of the present invention, 1 to 20% by weight of carbon nanotubes are mixed in the spinning solution preparation step.

Considering economical efficiency and dispersion stability, the multi-walled carbon nanotubes are preferable to the single wall or double walled carbon nanotubes and have a size of 5 to 100 nm and a length of 1 to 50 μm, 10 to 30 nm in diameter and 10 to 30 占 퐉 in length.

In the present invention, 10 to 80% by weight of metal nanoparticles and distilled water are mixed and dispersed by stirring in a bath at 40 to 60 ° C. for 2 to 3 hours with ultrasonic waves to improve the conductivity. Make an aqueous dispersion.

The metal nanoparticles are preferably metal nanoparticles of any one of gold, silver, nickel, copper, iron and titanium. Of these, silver nanoparticles having a particle size of 50 to 200 nm are preferably used Do.

There are many kinds of silver nanoparticles, such as spherical, elliptical, polyhedral, wire, rod-shaped, and the like. In order to improve the conductivity, wire type or bar size is preferable. However, Silver nanoparticles are preferably spherical in order to produce conductive fibers and obtain improved conductivity.

Generally, when conductive fibers are prepared by incorporating metal nanoparticles, a large amount of metal nanoparticles are required to have sufficient conductivity, which causes a problem of radioactive problems and cost increase. Therefore, when the metal nanoparticles are combined with the carbon nanotubes as in the present invention, the conductive path is ensured by the carbon nanotubes, so that even a relatively small amount of metal particles can provide sufficient conductivity. When the metal nanoparticles are less than 10% by weight, the conductivity is poor. When the metal nanoparticles are 80% by weight or more, the radioactivity is lowered.

100 parts by weight of the metal nanoparticle-carbon nanotube aqueous dispersion prepared above and 5-15 parts by weight of sodium alginic acid polymer are mixed to prepare a spinning solution. The solution of the alginate spinning solution in which the metal nanoparticles-carbon nanotubes are mixed and dispersed is mixed with tungsten Continuous fiber is produced through one ordinary spinning process and an acid treatment process is carried out to remove the surfactant for the purpose of improving the conductivity. In other words, after vacuum degassing and filtration to remove air bubbles, they are fixedly discharged through a gear pump, solidified in a calcium chloride coagulating solution, and then dried in a water bath, an oil bath, and an acid bath for acid treatment.

The acid treatment for removing the surfactant is preferably a mixed solution of any one of sulfuric acid, hydrochloric acid and nitric acid or any two or more of sulfuric acid, hydrochloric acid and nitric acid, and the concentration is 0.5 to 2.0N.

The conductive fiber wires coated with the fibers such as electric wires can be provided by using the fibers produced by the above-mentioned manufacturing method.

Therefore, according to the present invention, excellent conductivity of not more than 200? / Cm and excellent physical properties of not less than 80 MPa can be applied to a textile product based on a wearable device, It is possible to provide a metal nanoparticle-carbon nanotube-alginate conductive composite fiber which can be applied to a biomedical field such as a bioactuator, a biosensor, and also has a small emission of harmful substances in a spinning process and an excellent process characteristic.

1 and 2 are enlarged cross-sectional photographs of the electrically conductive conjugate fiber of the present invention.

The following examples illustrate non-limiting examples of preparing the electrically conductive conjugate fibers of the present invention.

[Example 1]

Sodium alginate (Protanal) purchased from FMC Biopolymer having an M / G value as shown in Table 1 was used. The analysis method of M / G ratio was analyzed using ¹ H-NMR (Jeo IJNM-LA 4 - with LFG, 400 MHz) based on ASTM F 2269-10 (Reapproved 2012). Carbon nanotubes and silver nanoparticles used in Table 2 were used.

5% by weight of carbon nanotubes ( CNT ) and 20% by weight of silver nanoparticles were dissolved in residual water and mixed for 60 minutes while projecting ultrasonic waves. 10 parts by weight of sodium alginate was slowly added to 100 parts by weight of the mixed solution while mixing with ultrasonic waves for 2 to 3 hours to prepare a spinning solution.

Name of sample G M M / G Example 1 0.88 0.53 0.6 Comparative Example 1 1.57 1.82 1.15

 G: Gluconic acid = 0.5 (A + C + 0.5 (B1 + B2 + B3))

 M: Mannuronic acid = B4 + 0.5 (B1 + B2 + B3)

subject Type Spec CNT MultiWall Dia 20 nm, Length 10 μm
5% Water dispersion Ag Spherical 80 nm

Sodium alginate solution (dope) was prepared, and the bubbles were removed while keeping the neutral state. The dope was removed by adjusting the discharge amount with a gear pump so as to be 3.5 denier through a nozzle having a diameter of 0.1 mm and a hole number of 1,525 holes.

At this time, the stretching ratio was fixed at 1.1, and the winding speed was 5 m / min. The coagulation bath was a 1M calcium chloride solution. The CNT-alginate fibers were then washed with 1% aqueous solution of Triton X-100, a non-ionic surfactant, to remove unreacted salts. Then, an acid bath for oil production, an acid bath for acid treatment, Followed by coarsening to obtain an electrically conductive composite fiber. Here, the acid treatment is intended to improve the electric conductivity by removing the surfactant such as the dispersant contained in the emulsion and the additive by 0.5N nitric acid treatment.

[Comparative Example 1]

The same procedure was carried out as in Example 1, except that sodium alginate (Protanal) purchased from FMC Biopolymer having an M / G value as shown in Table 1 was used as a raw material of alginate soda.

[Characteristic Analysis of Conductive Fiber]

The conductivities of the fibers prepared in the Examples and Comparative Examples were measured using a 2-probe meter, and the resistance values of the final fibers were obtained through the following conversion equations.

Equation 1] ----

(ρ (Ω / cm) is the resistivity, A is the cross-sectional area of the circular fiber, L is the resistance measurement distance, and S / cm, the unit of final conductivity value, is the reciprocal of the resistivity value.)

(Test standard: ① Conductivity: 2probe method measurement

② Strength and elongation: Average value of 10 measurements per sample with a short fiber strength meter)

M / G ratio Conductivity (Ω / cm) Example 1 0.6 46 Comparative Example 1 1.15 102

The diameter of the conductive composite fibers of Example 1 and Comparative Example 1 was measured, and the tensile strength (MPa) and elongation (%) per unit area were measured. The tensile strength and elongation of the Ag / CNT / Alginate conductive composite fiber showed sufficient physical properties to be used as the conductive fiber as shown in Table 4.

Name of sample diameter (탆) Tensile strength (MPa)  Elongation (%) Example 1 31.04 179 8.6 Comparative Example 1 33.21 130 5.6

Even though the content of metal Nano conductive additive was small, it showed excellent conductivity. It was found that carbon nanotube (CNT) secures a conductive path and thus has a synergistic effect of electric conductivity.

Claims (5)

10 to 80% by weight of metal nanoparticles, 1 to 20% by weight of multi-walled carbon nanotubes, and distilled water as a remainder, and the resulting mixture is stirred at 40 to 60 ° C in a hot water bath for 2 to 3 hours with ultrasonic waves. After making the aqueous dispersion,
The metal nano-particle-carbon nanotube aqueous dispersion was mixed with a sodium alginic acid polymer having a ratio of mannuronic acid and glutaric acid (M / G ratio) of 0.6 to 1.0, wherein sodium alginic acid And 5 to 15 parts by weight of a polymer were mixed and stirred under ultrasonic wave to prepare a spinning solution of metal nanoparticle-carbon nanotube-alginate,
The water is degassed to remove air bubbles, filtered and then discharged in a fixed quantity through a gear pump to solidify in a coagulating solution of calcium chloride, followed by drying in an aqueous acid bath for water treatment, oil production and acid treatment, A method for producing a conductive composite fiber. delete The method according to claim 1,
Wherein the acid solution is a mixed solution of any one of sulfuric acid, hydrochloric acid and nitric acid or any two or more of sulfuric acid, hydrochloric acid and nitric acid, and the concentration is 0.5 to 2.0 N. The method according to claim 1,
Wherein the metal nanoparticles are metal nanoparticles of any one of gold, silver, nickel, copper, iron, and titanium. 5. The method of claim 4,
Wherein the silver nanoparticles are spherical silver nanoparticles having a particle diameter of 50 to 200 nm.

Images