RU2522884C2 - Method of obtaining nanomodified binding agent - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: invention relates to the field of obtaining composite materials based on resins, dispersed by a nanomodifier - carbon nanotubes (CNT), which can be applied for introduction into highly viscous bases in obtaining polymer composite materials for wide spectrum of applications. A method of obtaining a binding agent includes introduction of the nanomodifier - carbon nanotubes - into a base with further ultrasonic dispersion of the nanomodifier in the base, with a furfural-acetone resin being used as the base; the carbon nanotubes are introduced in the base in an amount of 0.001-30 wt %. Before introduction the carbon nanotubes are dehydrated; the process of ultrasonic dispersion is carried out at room temperature in a time range from 5 minutes to 12 hours. The method realisation does not require application of a solvent.

EFFECT: method provides uniform distribution of CNT throughout the volume of the material base, in which the said binding agent is introduced, and reduction of time for obtaining the said binding agent.

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Description

The invention relates to the field of production of composite materials based on resins dispersed by a nanomodifier — carbon nanotubes (CNTs), which can be used to introduce into highly viscous substrates in the preparation of a wide range of polymer composite materials.

It is known from the prior art that a unique combination of the properties of CNTs, such as small size, large specific surface area, thermal and chemical stability, high strength, is of interest and opens up great opportunities for their application. They are widely used in various fields of industry, in particular in the production of adhesives, coatings, and as reinforcing fillers for composite materials. In addition to improving the mechanical properties of composites, the use of CNTs in their composition can significantly increase their thermal conductivity. Due to the introduction of CNTs into polymers, the latter become more resistant to temperature, aggressive chemicals, extreme pressures, and abrasion.

One of the main methods for introducing CNTs into the bases for obtaining various types of suspensions is ultrasonic dispersion. Using this method allows to obtain homogeneous and chemically pure mixtures (suspensions) of solid particles in liquids, such as resins. Dispersion of suspensions is carried out under the influence of ultrasound on aggregates of solid particles, interconnected by the forces of adhesion, sintering or cleavage. With ultrasonic dispersion of mixtures, the dispersion of the product increases by several orders of magnitude compared to traditional mechanical grinding. However, at this stage there are certain difficulties, for example, the introduction of CNTs into resins, which are the basis for a large number of composite materials with a wide range of applications. Resins are known to have high viscosity, which makes it impossible to directly inject CNTs into them. In this regard, it is necessary to select a special solvent liquid in which it will be possible to disperse the nanotubes, after which it (the solvent) is evaporated, and thus, the CNTs are converted into resin.

In turn, due to strong van der Waals interactions, CNTs form clusters leading to rather large aggregates, insoluble in most liquids, which complicates the selection of the required solvent (See Shane D. B., Zhenyu S., David R. , Philip VS, James PH, Jonathan NC Milticomponent Solubility parameters for Single-Walled Carbon Nanotube Solvent Mixtures. ACS Nano: 2009, 3 (8), 2340-2350).

Moreover, even if this problem is solved, the question of how to transfer dispersed nanotubes from a solvent to the desired resin remains relevant. For this, CNTs are dispersed in acetone, after which the resin is dissolved in it, followed by evaporation of the solvent. This is all a fairly time-consuming process with possible loss of substance and additional time (See Toshiki, O., Keiichi S., Kazuhiro M. Process for producing carbon nanotube reinforced composite material. US 2006/0058443 A1, publ. March 16, 2006) .

A known method of producing a binder, according to which fullerene C60, open CNTs and fulleroid multilayer nanomodifier astralen in the form of a suspension in acetone, is mixed by ultrasound using an immersion ultrasonic emitter, after which these components are introduced into the epoxy resin. A hardener, 4,4′-diaminodiphenylsulfone, is introduced into the resulting mixture to obtain a polymer binder (see RF patent No. 2223988, IPC C08L 63/00, C08K 13/02, B32B 17/10, C08K 13/02, C08K 3/04, С08К 5/17, С08К 7/02, С08К 7/06, С08К 7/14, published on 02.20.2004).

As a result of the analysis of the known method, it should be noted that it involves the introduction of various nanomodifiers in the form of a suspension in an organic diluent into a viscous epoxy resin, in which they are aggregated and precipitated. This precipitate is difficult to mix after storage, and with subsequent redispersion it is very difficult to obtain a binder with a modifier of nanoscale level. Thus, the disadvantages of this method include the impossibility of redispersing and aggregating the nanomodifier in storage conditions. In addition, the disadvantages of this method include the relative instability of the obtained dispersions, as well as certain difficulties associated with the fact that the resulting binder is dissolved in acetone, as in a solvent, which suggests the need for a separate stage of evaporation of the latter, after introducing it into the epoxy resin, which , in turn, causes additional time and labor costs.

A known method of manufacturing a nanomodified binder, comprising obtaining a concentrate by dispersing particles of a nanomodifier — nanotubes in a matrix during ultrasonic treatment and introducing the said concentrate into a binder, at least one condensation resin with a viscosity of more than 600 cP is used as a matrix and a binder, and the ultrasonic effect upon receipt of the concentrate is carried out with a radiation power of 1 to 5 kW and an amplitude of 20 to 80 μm (see RF patent No. 2415884, IPC C08J 3/20, C08J 5/04, B3 2B 27/18, published on 04/10/2011) is the closest analogue.

As a result of the analysis of the known method, it should be noted that the use of very viscous resins as a binder prevents the complete dispersion of CNTs in them. In addition, given that CNTs have the ability to form insoluble clusters that stick together in aggregates, the direct dispersion of the latter into very viscous systems seems to be a rather laborious process, which, however, does not guarantee a uniform distribution of CNTs over the bulk of the base.

The technical task of the invention is to develop a method for producing a nanomodified binder, providing a uniform distribution of CNTs over the volume of the base material in which this binder is introduced, and reducing the time to obtain this binder.

The technical result is ensured by the fact that in the method for producing a nanomodified binder, comprising introducing carbon nanotubes into the base of the nanomodifier — followed by ultrasonic dispersion of the nanomodifier at the base, using furfural-acetone resin as the basis, carbon nanotubes being introduced into the base in an amount of 0.001 ... 30 wt.%, before introduction to the base, they are dehydrated, and the process of ultrasonic dispersion is carried out at room temperature in the time range from 5 minutes to 12 hours.

The claimed method is as follows.

The calculated amount of nanomodifier (CNT) in the concentration range from 0.001 wt.% To 30 wt.% Is dehydrated and a furfural acetone resin having a viscosity of about 150 cP is introduced into the matrix (solvent). Next, the resulting suspension is poured into a container for ultrasonic treatment. To conduct ultrasonic treatment of the suspension, the process of ultrasonic dispersion of CNTs is started. The parameters of ultrasonic exposure are selected depending on the amount of CNTs in the base, the volume of this base, etc. Since the mixture is heated in the process of dispersion, it is carried out with continuous cooling in a water bath while maintaining a constant room temperature of about 22 ... 25 ° C.

The dispersion time varies from 5 minutes to 12 hours, depending on the amount and type of input nanomodifier. The dispersion time is determined experimentally each time, namely the end of the reaction, for example, is monitored by high resolution optical microscopy. The presence of particles larger than a micron is recorded, and when they cease to be detected, dispersion is considered complete.

The choice of a furfural-acetone resin as a solvent is based on the fact that this resin has several characteristics that are very important from a technical point of view. On the one hand, it is a suitable solvent for CNTs and its viscosity is relatively low, of the order of 150 cP; therefore, dispersion is possible in it. On the other hand, the dispersion of CNTs directly into the resin avoids the additional and rather long-term stage of solvent evaporation, since it is possible to introduce the obtained binder directly into the epoxy resin.

For binders used in the manufacture of prepregs for composite materials, the quantitative ratio of nanomodifier is 0.001 ... 0.1 wt.%. This ratio provides improved performance for composite materials. In the case of manufacturing complex small-sized parts, it is impossible to use carbon fiber, and in such cases it is the introduced nanotubes of CNTs that act as a reinforcing component, and therefore their concentration in the matrix can reach 30 wt.%. Dispersion time varies depending on the amount and type of input nanomodifier and is determined experimentally. The dispersion process is carried out at room temperature and does not require additional heating, as it is exothermic.

An example implementation of the method.

On an analytical balance, 0.4 g (0.003 wt.%) Of the Bayer MAterialScience BAYTUBES C 150 P CNT nanotubes were measured, preliminary calcining them to constant mass in the furnace in order to evaporate the water present as an impurity. 130 g of furfural acetone resin was also measured and placed in a container, then CNTs were added to furfural acetone resin, and then ultrasonic dispersion was carried out, which was carried out for 360 minutes with continuous cooling of the dispersible solution in a water bath. The temperature of the solution was maintained at about 25 ° C. Ultrasonic dispersion was carried out by means of a flowing ultrasonic mixer containing an ultrasonic magnetostrictive transducer (for example, model ПМС1-1), the operating frequency of which was 22 ± 1.0 kHz, the maximum electric power was 1.2 kW, and the nominal displacement amplitude in the output section without acoustic load was not less than 10 microns. The converter was equipped with an electromagnetic oscillation amplitude sensor. The output diameter of the transducer is 35 mm. For dispersion, an ultrasonic magnetostrictive transducer was connected to an ultrasonic electric generator with a maximum electric power of 3.0 kW and a power supply of 220 V. The operating frequency of the ultrasonic generator was 22 ± 1.0 kHz.

As a result, a homogeneous, time-stable, black suspension of dispersed nanotubes in a furfural-acetone resin was obtained. The viscosity of the resulting compositions ranged from 120 to 10,000 cP, depending on the concentration of CNTs introduced into the furfural acetone resin.

As a result, the obtained binder can be used as an active diluent for epoxy or other resins when CNTs are introduced into them.

Claims (1)

A method of producing a nanomodified binder, comprising introducing carbon nanotubes into the base of the nanomodifier — followed by ultrasonic dispersion of the nanomodifier into the base, characterized in that a furfural-acetone resin is used as the base, and carbon nanotubes are introduced into the base in an amount of 0.001-30 wt.% With respect to the base , before introducing them into the base, they are dehydrated, and the process of ultrasonic dispersion is carried out at room temperature in the time range from 5 minutes to 12 hours.