RU2420350C2 - Microcapsules with water or water solution (versions) and method of their production (versions) - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention maybe used for efficient fire extinguishing, fast cooling of overheated structures and production of lower-flammability compounds. Microcapsules have a micro-sphere-like core containing water or water solution in gel state, main shell around said core to provide for core stable shape and composition and rule out water evaporation therefrom the core, and, additionally, comprises outer shell with lyophilic properties. Versions of proposed methods comprises producing aforesaid core via interaction of appropriate initial water solutions to be placed in microsphere and containing appropriate components of the shell with components of solutions to be precipitated and used for producing and cross-linking of gel, and producing additional lyophilic shell via interaction of components of initial solutions with appropriate components in organic medium.

EFFECT: high efficiency in fire extinguishing or fast cooling of overheated structures.

21 cl, 1 tbl, 10 ex

Description

The invention relates to microcapsules containing water or aqueous solutions, and methods for microencapsulation of water or aqueous solutions for various applications, and more particularly to obtaining "dry" or "granular" water in the form of microcapsules containing water or aqueous solutions, used in particular for effective suppression of fire, protection against overheating of industrial reactors, obtaining compounds of reduced combustibility, and may find application in other industries, such as food, pharmaceutical industry, and also in the production of mineral fertilizers.

Water, due to its unique physicochemical properties and its high prevalence in nature and, accordingly, cheapness, has always been the main means of fighting fire.

Of all known liquids (under normal conditions), water has the highest heat of vaporization, which, basically, determines its effectiveness in fighting fire. In addition, water is completely non-toxic, including in fire extinguishing conditions, and does not introduce toxic or corrosive components into combustion products.

However, water as a fire extinguishing agent has several disadvantages.

Due to the rapid development of electrical engineering and electronics, the objects of which are currently saturated with industry and everyday life, it has become dangerous to use water to fight fire because of its conductivity, which leads to short circuits and damage to expensive equipment.

The ability of water to quickly spill, penetrate into gaps, cavities and be sorbed by many materials leads to damage to documents, books, valuables and equipment.

Due to the rapid spill, water cannot be accumulated in the volume of a burning object, therefore its consumption and the required feed rate are extremely high.

Therefore, in the second half of the XX century. An industry has been created in the world for the production of new fire extinguishing agents in liquid and gaseous state based on fluorinated and fluorine-bromine-containing hydrocarbons.

Undoubtedly, these substances have exceptional fire extinguishing efficiency, based on the occurrence of heavy free radicals during thermal exposure, which break the kinetic chains of the combustion process. These substances are also safe for electrical and electronic systems.

However, the cost of these products is high. Moreover, their decay products were not only toxic to humans directly, but also cause the destruction of the ozone protective layer of the Earth’s atmosphere. This served as the basis for the international ban (Montreal Protocol) of the production and use of a number of these products used for fire fighting in fire safety systems.

Therefore, the problem of the ability to extinguish fires with "dry" water, which does not cause the death of documents and books, electronic devices, does not provoke short circuits in electrical systems, seems to be fundamentally important.

In addition, “dry” water can be used proactively in situations of overheating of chemical and nuclear reactors and in the presence of a threat of thermal explosion. The reactor, which is in the overheating mode, can be filled with a large amount of “dry water”, and it is possible to create high embankments from it, up to filling the entire volume of the working room.

Packages with “dry” water can solve problems with transporting water to its field of application. For example, packages with “dry” water can be dropped from aircraft, since this does not cause a hydraulic shock, which leads to the destruction of containers with liquid water, which is important when delivering water to emergency zones. Packages with dry water can be used in zero gravity.

Various methods are known for producing “dry” or “free-flowing” water by forming polymer microcapsules containing water.

For example, the American company “3M” proposed experimental samples of an aqueous solution of fertilizers (nitrates, phosphates) in the form of microcapsules having a shell of low melting polyethylene (Prospectus of the company “3M”, 1974). By the nature of the microcapsules, it can be assumed that the tube-in-tube method used in the inverted form to obtain capsules with fat-soluble vitamins, validol, nitroglycerin solution and the like was used to obtain microcapsules. However, this method is only suitable for small-scale production. The resulting 3M microcapsules were fragile and quickly lost their shape.

A known method of producing microcapsules, in which crystalline hydrates of salts are used as the core of water-containing microcapsules (DE, 102005002169, A). In this case, microencapsulation is performed in fusible materials having a melting point higher than that of crystalline hydrates. The water content is not indicated, however, in known crystalline hydrates it does not exceed 50% by weight, which is not effective for fire fighting. In addition, the presence of salts leads to corrosive effects on the objects of protection.

Methods for encapsulating aqueous solutions of drugs, biologically active substances and cultures are also known.

For example, a method for producing a microencapsulated pharmaceutically active agent is known, comprising: dispersing an aqueous solution of a pharmaceutically active agent in a solution containing an organic polymer solvent and a polymer dissolved therein to form a basic water-in-oil emulsion; mixing the main emulsion with an aqueous external phase containing water and a surfactant, and, under the conditions of air supply above the mixture, dispersing the specified main emulsion in the specified aqueous external phase to obtain a product containing a microencapsulated pharmaceutically active agent in a dispersed mixture (US, 6204308 , AT). In this case, polyethylene carbonate is used as the polymer, and said microencapsulated pharmaceutically active agent contains a coating, matrix, or polyethylene carbonate shell. However, the resulting product has a chaotic distribution of the active agent due to the uneven distribution of polyethylene carbonate in its volume and may have an uneven thickness shell on the surface, which, on the one hand, leads to unpredictable release of the agent, on the other hand, it does not guarantee the filling of the microcapsule with the agent, indicated the shell or coating is unstable to water and does not interfere with the evaporation of water contained in the microparticles. This method is characterized by the instability and multi-stage process, in this regard, it is difficult in industrial implementation.

A known method for producing chitosan / alginate microparticles, including: spray drying an aqueous solution containing a biologically active agent and sodium alginate through nozzles at a temperature of 140 ° C, to obtain microparticles; their subsequent crosslinking with calcium chloride in a 3% solution of acetic acid with stirring and the subsequent immersion of crosslinked microparticles in a solution of chitosan or poly-1-lysine in a 3% solution of acetic acid, after which the resulting microparticles are separated by centrifugation, washed with distilled water and dried at room temperature. The resulting microparticles have a spherical shape with a glossy surface. Crosslinking was used to increase the number of individual gelled particles inside the shell (Burku Saim A., Atilla Khinkal, Skida Senel. Production of chitosan / alginate microparticles for vaccination of the mucous membrane. 15th International Microencapsulation Symposium, Parma, Italy, September 18-21, 2005, p. 339-330; Burcu Sayim A., Atilla Hincal, Scyda Senel. Preparation of chitosan-alginate microparticles for mucosal immunization. 15th International Symposium on Microencapsulation, Parma (Italy), September 18-21, 2005, p.329- 330). However, the content of the aqueous solution in the obtained microparticles is about 15%, which is associated with a significant evaporation of water when spraying the initial aqueous solution at a temperature above 100 ° C. In addition, the chitosan alginate complex compounds formed by the remaining carboxyl groups remaining in the alginate after crosslinking with calcium ions are unstable to water and do not interfere with the evaporation of water contained in microparticles.

Known lysozyme-containing chitosan-coated microspheres obtained by the method of sequential emulsification in media with a mass ratio per unit volume: 4% alginate, 0.1% chitosan, 15% calcium chloride, 20% lysozyme and 10% content of heat-activated Vibrio anguillarum (L. Zorzin, Mu Kokchetto, D. Voinovich, A. Markuzzi, J. Filippovich-Grzhik, K. Kasarsa, K. Mulloni and G. Sava. Lysozyme-containing chitosan coated microspheres for oral vaccination 15th International Symposium Microencapsulation, Parma, Italy, September 18-21, 2005, pp. 153-154; L. Zorzin, M. Cocchietto, D. Voinovich, A. Marcuzzi, J. Fillipovich-Grcic, C. Casarsa, C. Mulloni and G. Sava. Lysozime-containing chitosan-coated alginate microspheres for oral immunization. 15th International Symposium on Microencapsulation, Parma (Italy), September 18-21, 2005, p. 153-154). However, the chitosan-alginate complex compounds formed by the carboxyl groups remaining free in the alginate after its crosslinking with calcium ions are unstable to water and do not prevent the evaporation of water contained in microparticles during their storage.

In addition, due to the uneven distribution of free carboxyl groups in the surface layers of crosslinked microparticles, the shell thickness of the chitosan-alginate complexes is also not the same, and the microparticles have a high polydispersity.

A known method of producing microcapsules (WO 2005/018794 or GB 2388581, A; or RU, 2006108860, A) having a solid hydrophobic shell, containing encapsulated water in the form of drops or drops that are additionally encapsulated in the specified shell or with its help, and active an ingredient or ingredients dissolved or incorporated into an encapsulated drop or drops, comprising the following steps:

a) obtaining an aqueous phase and one or more active ingredients dissolved or incorporated into the aqueous phase;

b) obtaining a hydrophobic phase in molten form;

c) dissolving or incorporating the encapsulating material or a mixture of encapsulating materials into said aqueous phase or into a hydrophobic phase;

d) combining said aqueous and hydrophobic phases and homogenizing or mixing the phases to form a water-in-oil emulsion;

e) encapsulating the aqueous phase in an emulsion, thereby forming a dispersion comprising encapsulated droplets of water, and wherein the active ingredient or active ingredients are encapsulated in drops of water;

f) treating the dispersion obtained in step e) to form microcapsules in which the encapsulated aqueous droplets are further encapsulated in or using a cured hydrophobic shell.

In this case, the microcapsule is obtained by spraying the specified water-in-oil emulsion upon cooling. In this method, the aqueous phase is selected from the group consisting of water or a mixture of water and any water-miscible solvent, such as ethanol, ethylene glycol, glycerol. The hydrophobic phase is selected from the group consisting of animal oils and fats, fully hydrogenated vegetable or animal oils, unsaturated hydrogenated monoglycerides of fatty acids and other materials.

The encapsulating material is selected from the group consisting of hydrocolloids: sodium alginates, gum arabic, glue, starch, modified starch, guar gum, agar glue, pectin and other glues, chitosan, xanthan, gelatin, hyaluronic acid, cellulose derivatives, acrylic copolymers protein, shellac, zein, any synthetic or natural water-soluble polymers, any water-miscible microparticles, such as silicon dioxide, titanium dioxide, synthetic or natural granular polymer balls or any miscible solids suitable for agglomeration (sintering).

In this case, the combination of the aqueous phase with the hydrophobic phase can be carried out by mixing, homogenization - by mixing with a shift of the layers or linear mixing, and encapsulation is carried out by coacervation or agglomeration, or gelation, or crosslinking.

In this case, encapsulation by coacervation can be carried out using encapsulating material with an increase in its solubility by increasing the temperature, changing the pH, adding hydrocolloids, or any acceptable coacervation initiating agents. And in this case, the encapsulating material is selected from the group consisting of shellac, zein, synthetic or natural hydrophobic polymers, such as fats, emulsifiers, waxes or mixtures thereof.

In this case, the encapsulation by agglomeration can be carried out using solid microparticles as the encapsulating material, while the microparticles, for example silicon dioxide, titanium dioxide, synthetic or natural granular polymer beads or other water-insoluble solid particles, are fused into the film surrounding the aqueous phase.

In this case, encapsulation can be carried out by gelation, and at the same time, the gelation of the aqueous phase in the emulsion can be carried out by lowering the temperature of the emulsion to the gelation temperature of the encapsulating material, while the encapsulating material is selected from the group consisting of gelling hydrocolloids, for example gelatins, starch, agar glue and others.

In addition, the encapsulation of the aqueous phase can be carried out by crosslinking using an encapsulating material selected from the group consisting of proteins, gelatins, starches, chitosan, cellulose derivatives, synthetic or natural water-soluble polymers suitable for heat crosslinking, crosslinking when the acid-base state changes environment or during chemical treatment, and mixtures thereof.

Obtained using the method described above, one microcapsule may contain from 1 to 100 aqueous drops placed in a hydrophobic matrix shell, and the active ingredient or active ingredients dissolved in or included in aqueous drops.

However, in the method for producing microcapsules described above, the multi-stage technology makes the method difficult to implement in production. In addition, when spraying a water-in-oil emulsion to form a shell around water-containing drops of the aqueous phase, which tend to agglomerate, a thick shell forms, which occupies a significant place in the volume of the microcapsule. At the same time, the resulting microcapsule contains water in an amount of not more than 50% by weight, and the shell contains wax, fats and other combustible substances, which, in total, excludes the possibility of using the resulting microcapsules as a fire extinguishing agent.

In addition, the method of producing microcapsules by spraying determines the high polydispersity of the obtained microcapsules, which, when using such microcapsules at high temperatures, leads to non-simultaneous release of water from them and, consequently, inefficient evaporation of water, which prevents the use of such microcapsules for extinguishing fires or cooling protected from overheating of objects.

When developing the present invention, the task was to create water-containing microcapsules that provide maximum efficiency for the targeted use of the water contained in them, including to extinguish fires or to quickly cool objects, such as reactors during abnormal overheating, and certain qualitative and quantitative indicators must be achieved microcapsules:

- the content of water or an aqueous solution in microcapsules should be as high as possible, practically not less than 90% by weight,

- the content of the combustible part, which is determined by the mass fraction of the shell, in the microcapsule should be minimized and the microcapsules must be strong, free-flowing and non-melting,

- the polydispersity of the finished microcapsules (variation in size) should be minimal so that when the critical temperature for the release of water or an aqueous solution is reached, the effect of water release (evaporation) is simultaneous (cooperative).

The task was also to create a microcapsule forming core that ensures that water or an aqueous solution is held uniformly throughout the entire volume of the core, while providing a spherical shape of the core with a uniform distribution of pressure of water or aqueous solution from the inside onto the surface of the sphere, which is also most suitable for placing a shell of uniform thickness .

In addition, the task was to develop a microcapsule containing water or an aqueous solution in the core and having a shell that prevents the evaporation of water from the core.

The task was also set to provide increased wettability of the outer surface with lyophilic liquids by creating additional shells on the surface of the microcapsule. This is important when using water-containing microcapsules as fillers, for example, polymer compounds with reduced flammability.

It is known that increasing the wettability of the filler surface with a liquid polymer matrix (decreasing the wetting angle) leads to the possibility of increasing the degree of filling, which is important for increasing the resistance of materials to ignition and flame propagation when filled with microcapsules with water. In addition, in this case, after curing, a higher strength of the compound is provided, which is an important technical characteristic. Therefore, achieving lyophilization of the surface of microcapsules with water is an essential task for their use as fillers of polymer compounds of reduced combustibility.

When creating the invention, the task was also set to develop methods for producing microcapsules containing water or an aqueous solution, which allows the formation of uniformly sized gelled drops of an aqueous solution (water-containing microspheres), coated with a coating that prevents evaporation of water during storage, and which have a stable strength and good flowability and high in water.

The problem was solved by creating a microcapsule containing water or an aqueous solution in a gel state, having a core in the form of a microsphere, containing water or an aqueous solution, gelled with gelling electrolytes having carboxyl groups dissolved in said water or an aqueous solution.

Moreover, according to the invention, the microcapsule as these gel-forming polyelectrolytes may contain sodium alginate, and / or pectin, and / or gum arabic, and / or any other polysaccharides containing carboxyl groups.

The problem was also solved by creating a microcapsule containing water or an aqueous solution in a gel state, having a core in the form of a microsphere, containing water or an aqueous solution, gelled with crosslinked calcium ions dissolved in said water or said aqueous solution of gelling polyelectrolytes having carboxyl groups, and while having on the surface of the microspheres the main shell that prevents the evaporation of the water contained in the specified core.

Moreover, according to the invention, the microcapsule as these gel-forming polyelectrolytes may contain sodium alginate, and / or pectin, and / or gum arabic, and / or any other polysaccharides containing carboxyl groups.

Moreover, according to the invention, it is reasonable that the main shell of the microcapsule has a thickness minimally necessary to prevent evaporation of the water contained in the core.

In addition, according to the invention, it is advisable that the main shell was formed by complex compounds of high molecular weight first co-components that are carriers of the same charge and high-molecular second co-components that are carriers of the opposite charge, placed on the outer surface of the indicated core.

Moreover, according to the invention, it is desirable that the main shell was formed by complex compounds of high molecular weight first co-components having negative charges on the polymer molecule, with high-molecular-weight second co-components having positive charges on the polymer molecule.

In addition, according to the invention, it is desirable that the main shell be formed by complex compounds of high molecular weight first co-components having negative charges on the polymer molecule due to the presence of carboxyl groups, with high-molecular second co-components having positive charges on the polymer molecule due to the presence of amine groups.

Moreover, according to the invention, it is desirable that the main shell be formed by complex compounds of cellulose acetate phthalate with chitosan.

In addition, according to the invention, it is possible that the main shell was formed by complex compounds of polyacrylic acid with polyvinylpyrrolidone.

The problem was also solved by creating a microcapsule containing water or an aqueous solution in a gel state, while having a core in the form of a microsphere containing water or an aqueous solution, gelled with crosslinked calcium ions dissolved in said water or said aqueous solution of gelling polyelectrolytes having carboxyl groups, and while having a main shell on the surface of the microspheres, preventing the evaporation of the water contained in the specified core, and an outer additional shell having w lyophilic properties. Moreover, according to the invention, the microcapsule as these gel-forming polyelectrolytes may contain sodium alginate, and / or pectin, and / or gum arabic, and / or any other polysaccharides containing carboxyl groups.

Moreover, according to the invention, it is reasonable that the main shell of the microcapsule has a thickness minimally necessary to prevent evaporation of the water contained in the core.

In addition, according to the invention, it is advisable that the main shell was formed by complex compounds of high molecular weight first co-components that are carriers of the same charge and high-molecular second co-components that are carriers of the opposite charge, placed on the outer surface of the indicated core.

Moreover, according to the invention, it is desirable that the main shell was formed by complex compounds of high molecular weight first co-components having negative charges on the polymer molecule, with high-molecular-weight second co-components having positive charges on the polymer molecule.

In addition, according to the invention, it is desirable that the main shell be formed by complex compounds of high molecular weight first co-components having negative charges on the polymer molecule due to the presence of carboxyl groups, with high-molecular second co-components having positive charges on the polymer molecule due to the presence of amine groups.

Moreover, according to the invention, it is desirable that the main shell be formed by complex compounds of cellulose acetate phthalate with chitosan.

In addition, according to the invention, it is possible that the main shell was formed by complex compounds of polyacrylic acid with polyvinylpyrrolidone.

Moreover, according to the invention, it is advisable that the additional outer shell was formed by polycarbodiimides.

Moreover, according to the invention, it is possible that the additional outer shell was formed by polyurea.

Moreover, according to the invention, the described microcapsules have a diameter in the range from 0.25 to 5.0 mm with a diameter distribution of at least 90% and contain water or an aqueous solution in an amount of at least 90% by weight of the microcapsule.

Moreover, the microcapsules according to the invention may contain aqueous solutions comprising useful components, for example therapeutically useful substances, suspensions of microorganism cultures, and other components compatible or inert with respect to said polyelectrolytes and co-components.

The problem was also solved by creating a method of microencapsulation of water or aqueous solutions to obtain a microsphere containing water or an aqueous solution, gelled with crosslinked calcium ions dissolved in said water or an aqueous solution of gelling electrolytes, comprising the following steps:

a) obtaining a starting aqueous solution containing at least gelling polyelectrolytes having carboxyl groups dissolved in water;

b) obtaining a precipitating aqueous solution containing at least one source of divalent calcium ions dissolved in it;

c) introducing the initial aqueous solution obtained in step a) into the precipitating aqueous solution obtained in step b) with drops while stirring the precipitating solution at a temperature of 20-25 ° C. for a time sufficient to form a dispersion containing microspheres in the precipitating solution in which the initial aqueous solution is in the form of a gel formed by gelling polyelectrolytes obtained in step a), crosslinked with divalent calcium ions obtained in step b);

d) isolating the microspheres obtained in step c) from the dispersion of the precipitating solution by filtration;

e) placing the obtained microspheres in a tightly closed container, dried from moisture.

Moreover, according to the invention, it is advisable to use sodium alginate, and / or pectin, and / or gum arabic, and / or other polysaccharides containing carboxyl groups as the indicated gelling polyelectrolytes, using aqueous solutions of calcium dichloride and / or calcium as a source of divalent calcium ions lactate and / or calcium glycerophosphate, and / or any other water soluble calcium salts.

The problem was solved by creating a method of microencapsulation of water or aqueous solutions to obtain a microcapsule having a core in the form of a microsphere containing gelled water or an aqueous solution, and a main shell that prevents evaporation of the water contained in the core, comprising the following steps:

a) obtaining an initial aqueous solution containing at least gelling polyelectrolytes having carboxyl groups and high molecular weight first co-components that are of the same charge and are acceptable for forming the main shell dissolved in water;

b) obtaining a precipitating solution containing at least one source of divalent calcium ions and high molecular weight second co-components dissolved in water that are carriers of a charge opposite to the charge of these first co-components obtained in step a) and acceptable for the formation of the main shell;

c) introducing the initial aqueous solution obtained in step a) into the precipitating solution obtained in step b) with drops while stirring the precipitating solution at a temperature of 20-25 ° C. for a time sufficient to form a dispersion containing microspheres in the precipitating solution, in which the initial aqueous solution is in the form of a gel formed by gelling polyelectrolytes obtained in step a), crosslinked with divalent calcium ions obtained in step b);

d) holding the dispersion obtained in step c) at a temperature of 20-25 ° C for a time sufficient to form microcapsules having a microsphere core obtained in step c), enclosed inside the main shell formed in the surface layer of the microsphere by compounds of the first co-components of the main shell obtained in step a) with the second co-components of the main shell obtained in step b);

e) isolating the microspheres obtained in step d) from the precipitating solution by filtration;

f) washing with water the microcapsules obtained in step e) and drying them in air;

g) treating the microcapsules obtained in step f) with an anti-caking agent;

h) placement of the obtained microcapsules in a tightly closed container, dried from moisture.

Moreover, according to the invention, it is advisable to use sodium alginate, and / or pectin, and / or gum arabic, and / or other polysaccharides containing carboxyl groups as said gel-forming polyelectrolytes.

Moreover, according to the invention, it is advisable to use aqueous solutions of calcium dichloride and / or calcium lactate and / or calcium glycerophosphate and / or any other water-soluble calcium salts as a source of divalent calcium ions.

Moreover, according to the invention, it is advisable to use high molecular weight compounds having negative charges on the polymer molecule as the first co-components of the main shell, which are of the same charge, and to use high molecular weight compounds, which are positive on the polymer molecule, as the second co-components of the main shell, which are carriers of the opposite charge charges.

Moreover, according to the invention, it is advisable to use high molecular weight compounds having negative charges on the polymer molecule due to the presence of carboxyl groups as the first co-components of the main shell, and to use high molecular weight compounds having positive charges on the polymer molecule due to the presence of amine groups as the second co-components of the main shell.

Moreover, according to the invention, it is desirable to use cellulose acetate phthalate as the first juice components of the main shell, and to use chitosan as the second juice components of the main shell.

In addition, according to the invention, it is possible to use polyacrylic acid as the first juice components of the main shell, and use polyvinylpyrrolidone as the second juice components of the main shell.

The problem was also solved by creating a method of microencapsulation of water or aqueous solutions to obtain a microcapsule having a core in the form of a microsphere containing water or the specified aqueous solution in a gel state, a main shell that prevents evaporation of the water contained in the core, and an additional shell with lyophilic properties, comprising the following steps:

a) obtaining a starting aqueous solution containing at least gelling polyelectrolytes having carboxyl groups and high molecular weight first co-components suitable for forming the main shell, which are of the same charge, dissolved in water;

b) obtaining a precipitating solution containing dissolved in water, at least one source of divalent calcium ions and high molecular weight second co-components acceptable for the formation of the main shell, which are carriers of a charge opposite to the charge of these first co-components obtained in stage a);

c) introducing the initial aqueous solution obtained in step a) into the precipitating solution obtained in step b) with drops while stirring the precipitating solution at a temperature of 20-25 ° C. for a time sufficient to form a dispersion containing microspheres in the precipitating solution, in which the initial aqueous solution is in the form of a gel formed by gelling polyelectrolytes obtained in step a) and crosslinked divalent calcium ions obtained in step b);

d) holding the dispersion obtained in step c) at a temperature of 20-25 ° C for a time sufficient to form microcapsules having a microsphere core obtained in step c), enclosed within a main shell formed by interaction in a surface a microsphere layer of the first co-components obtained in step a) with the second co-components obtained in step b);

e) isolating from the dispersion processed in step d) by filtering the microcapsules obtained in step d) and containing trace amounts of water on the outer surface of the main shell to be used later as the first juice component in the formation of the outer additional shell;

f) obtaining an organic medium containing an organic volatile liquid into which second co-components suitable for forming an additional shell having lyophilic properties are introduced and a dispersed catalyst soluble in water but not soluble in organic liquids;

g) introducing the microcapsules obtained in step e) into the organic medium obtained in step f) with stirring to obtain a dispersion of said microcapsules in said organic medium;

h) holding the dispersion obtained in step g) at a temperature of 20-25 ° C for a time sufficient to form on the outer surface of the microcapsules contained in the dispersion obtained in step g) and having a core in the form of a microsphere containing water or an aqueous solution surrounded by a main shell having traces of water on the surface of the outer additional lyophilic shell during the interaction of these first co-components of the additional shell in the form of trace amounts of water obtained in step e) with the second co-components ntami additional shell obtained in step f), in the presence of said catalyst;

k) isolating the microcapsules obtained in step h) from the organic medium by filtration;

m) washing the microcapsules obtained in step k) with the same organic volatile liquid as used in step f);

n) placing the microcapsules obtained in step m) in a tightly closed container, dried from moisture.

Moreover, according to the invention, it is advisable to use sodium alginate and / or pectin and / or gum arabic and / or other polysaccharides containing carboxyl groups as said gelling polyelectrolytes in step a).

Moreover, according to the invention, it is advisable to use aqueous solutions of calcium dichloride and / or calcium lactate and / or calcium glycerophosphate and / or any other water-soluble calcium salts as a source of divalent calcium ions in step b).

Moreover, according to the invention, it is advisable to use high molecular weight compounds having negative charges on the polymer molecule as the first co-components of the main shell, which are of the same charge, and to use high molecular weight compounds, which are positive on the polymer molecule, as the second co-components of the main shell, which are carriers of the opposite charge charges.

Moreover, according to the invention, it is advisable to use high molecular weight compounds having negative charges on the polymer molecule due to the presence of carboxyl groups as the first co-components of the main shell, and to use high molecular weight compounds having positive charges on the polymer molecule due to the presence of amine groups as the second co-components of the main shell.

In addition, according to the invention, it is desirable to use cellulose acetate phthalate as the first co-components of the main shell, and chitosan to be used as the second co-components of the main shell.

In addition, according to the invention, it is possible to use polyacrylic acid as the indicated first juice components of the main shell, and use polyvinylpyrrolidone as the specified second juice components of the shell base.

Moreover, according to the invention, it is desirable to use carbon tetrachloride or dimethyl carbonate as the indicated organic medium in step f).

Moreover, according to the invention, it is advisable to obtain a microcapsule having an additional shell formed by polycarbodiimides. Moreover, according to the invention, it is desirable to use a polyisocyanate or a mixture of polyisocyanate with toluene diisocyanates as the second juice components of the additional shell.

Moreover, according to the invention, it is advisable to use phospholene, preferably 1-oxo-1,3-dimethylphospholene, as a catalyst.

The problem was also solved by creating a method of microencapsulation of water or aqueous solutions to obtain a microcapsule having a core in the form of a microsphere containing water or the specified aqueous solution in a gel state, the main shell around the core and the outer additional shell having lyophilic properties, which includes the following steps:

a) obtaining an initial aqueous solution containing at least gelling polyelectrolytes dissolved in water having carboxyl groups, high molecular weight first co-components that are carriers of the same charge and suitable for the formation of the main shell, and first co-components acceptable for the formation of an additional lyophilic shell;

b) obtaining a precipitating solution containing at least one source of divalent calcium ions and high molecular weight second co-components, dissolved in water, suitable for the formation of the main shell, which are carriers of a charge opposite to the charge of these first co-components of the main shell obtained in step a);

c) introducing the initial aqueous solution obtained in step a) into the specified precipitating solution obtained in step b) with drops while stirring the precipitating solution at a temperature of 20-25 ° C for a time sufficient to form a dispersion containing microspheres in the precipitating solution in which the initial aqueous solution is in the form of a gel formed by gelling polyelectrolytes obtained in step a) and crosslinked divalent calcium ions obtained in step b);

d) holding the dispersion obtained in step c) at a temperature of 20-25 ° C for a time sufficient to obtain microcapsules having a microsphere core obtained in step c) enclosed within a main shell formed in the surface layer of the microsphere at the interaction between the first co-components of the main shell obtained in step a) and the second co-components of the main shell obtained in step b);

e) isolating the microcapsules obtained in step d) from the dispersion of the precipitating solution by filtration;

f) obtaining an organic medium containing an organic volatile liquid into which second co-components are acceptable, suitable for forming an additional shell, having lyophilic properties;

g) introducing the microcapsules obtained in step e) into the organic medium obtained in step f) with stirring to obtain a dispersion of the microcapsules in the organic medium;

h) holding the dispersion obtained in step g) at a temperature of 20-25 ° C for a time sufficient to obtain microcapsules having a microsphere core containing water or an aqueous solution in a gel state, surrounded by a main shell and an additional lyophilic shell;

k) isolating the microcapsules obtained in step h) from the organic medium by filtration;

m) washing the microcapsules obtained in step k) with the same organic volatile liquid as used in step f);

n) placing the microcapsules obtained in step m) in a tightly closed container, dried from moisture.

Moreover, according to the invention, it is advisable to use sodium alginate, and / or pectin, and / or gum arabic, and / or other polysaccharides containing carboxyl groups as said gel-forming polyelectrolytes.

Moreover, according to the invention, it is advisable to use aqueous solutions of calcium dichloride and / or calcium lactate and / or calcium glycerophosphate and / or any other water-soluble calcium salts as a source of divalent calcium ions.

Moreover, according to the invention, it is advisable to use high molecular weight compounds having negative charges on the polymer molecule as the first co-components, the main shell, which are of the same charge, and use high molecular weight compounds, having the polymer molecule, as the second co-components of the main shell, which are carriers of the opposite charge positive charges.

Moreover, according to the invention, it is advisable to use high molecular weight compounds having negative charges on the polymer molecule due to the presence of carboxyl groups as the first co-components of the main shell, and to use high molecular weight compounds having positive charges on the polymer molecule due to the presence of amine groups as the second co-components of the main shell.

Moreover, according to the invention, it is desirable to use cellulose acetate phthalate as the first juice components of the main shell, and to use chitosan as the second juice components of the main shell.

In addition, according to the invention, it is possible to use polyacrylic acid as the first juice components of the main shell, and use polyvinylpyrrolidone as the second juice components of the main shell.

Moreover, according to the invention, it is desirable to use carbon tetrachloride or dimethyl carbonate as an organic medium.

Moreover, according to the invention, it is advisable to obtain a microcapsule having an additional shell formed by polyureas, and in this case, hexamethylenediamine or polyethylene polyamine and / or other di- and polyamines soluble in water can be used as the first juice components, and a polyisocyanate can be used as the second juice components or a mixture of polyisocyanate with toluene diisocyanates.

Methods for microencapsulation of water or aqueous solutions according to the invention to obtain microspheres and microcapsules according to the invention are as follows.

In various embodiments of the microencapsulation methods of the invention, microcapsules are prepared having only the microsphere serving as their core and containing the target product — water or an aqueous solution in a gel state, or with the formation of one core shell around the indicated core, or the production of microcapsules having the specified core the microsphere, with the formation of the primary and secondary shells around the core, ensuring the stability of the form and composition of the microcapsule in various environments.

Moreover, in some embodiments of the methods for producing microcapsules, the main shell is formed simultaneously with the formation of the microsphere, which provides a technically rational microencapsulation process.

In other embodiments of the methods for producing microcapsules, residual amounts of water located on the surface of the microcapsules are used to form additional external lyophilic membranes that improve the performance of the microcapsules.

In this case, various aqueous solutions are used.

In the first method of microencapsulation to obtain microcapsules containing only microspheres, use:

- an initial aqueous solution containing one or more gelling polyelectrolytes having carboxyl groups, preferably sodium alginate, and / or pectin, and / or gum arabic, and / or other polysaccharides,

- precipitating aqueous solution containing dissolved in it, at least one source of divalent calcium ions, preferably aqueous solutions of calcium dichloride and / or calcium lactate and / or calcium glycerophosphate, and / or any other water-soluble calcium salts.

In the first embodiment of the second microencapsulation method according to the invention, to obtain microcapsules containing microspheres and provided with a main shell, use:

- the initial aqueous solution containing one or more gelling polyelectrolytes having carboxyl groups, preferably sodium alginate, and / or pectin, and / or gum arabic, and / or other polysaccharides, and dissolved first high molecular weight co-components of the future main shell of the microcapsule having the same charge, preferably cellulose acetate phthalate;

- precipitating aqueous solution containing dissolved in it, at least one source of divalent calcium ions, preferably aqueous solutions of calcium dichloride and / or calcium lactate and / or calcium glycerophosphate, and / or any other water-soluble calcium salt, and the second high molecular weight co-components of the future main shell of the microcapsule dissolved in it having a charge opposite to the first co-components of the main shell, preferably chitosan.

In the second embodiment of the second microencapsulation method according to the invention, to obtain microcapsules containing microspheres and provided with a main shell, use:

- the initial aqueous solution containing one or more gelling polyelectrolytes having carboxyl groups, preferably sodium alginate, and / or pectin, and / or gum arabic, and / or other polysaccharides, and dissolved first high molecular weight co-components of the future main shell of the microcapsule having the same charge, preferably polyacrylic acid;

- precipitating aqueous solution containing dissolved in it, at least one source of divalent calcium ions, preferably aqueous solutions of calcium dichloride and / or calcium lactate and / or calcium glycerophosphate, and / or any other water-soluble calcium salt, and the second high molecular weight co-components of the future main shell of the microcapsule dissolved in it having a charge opposite to the first co-components of the main shell, preferably polyvinylpyrrolidone.

In the first embodiment of the third microencapsulation method according to the invention, to obtain microcapsules containing microspheres and provided with a main shell and an additional shell, use:

- the initial aqueous solution containing one or more gelling polyelectrolytes having carboxyl groups, preferably sodium alginate, and / or pectin, and / or gum arabic, and / or other polysaccharides, and dissolved first high molecular weight co-components of the future main shell of the microcapsule having the same charge, preferably cellulose acetate phthalate;

- precipitating aqueous solution containing dissolved in it, at least one source of divalent calcium ions, preferably aqueous solutions of calcium dichloride and / or calcium lactate and / or calcium glycerophosphate, and / or any other water-soluble calcium salts, and the second high molecular weight co-components of the future main shell of the microcapsule dissolved in it having a charge opposite to the first co-components of the main shell, preferably chitosan.

In the second embodiment of the third microencapsulation method according to the invention, to obtain microcapsules containing microspheres provided with a main shell and an additional shell, use:

- the initial aqueous solution containing one or more gelling polyelectrolytes having carboxyl groups, preferably sodium alginate, and / or pectin, and / or gum arabic, and / or other polysaccharides, and dissolved first high molecular weight co-components of the future main shell of the microcapsule having the same charge, preferably polyacrylic acid, and the first co-components of a future additional shell, preferably di or polyamines,

- precipitating aqueous solution containing dissolved in it, at least one source of divalent calcium ions, preferably aqueous solutions of calcium dichloride and / or calcium lactate and / or calcium glycerophosphate, and / or any other water-soluble calcium salts, and the second high molecular weight co-components of the future main shell of the microcapsule dissolved in it having a charge opposite to the first co-components of the main shell, preferably polyvinylpyrrolidone.

In all microencapsulation methods of the invention, the stock solution is supplied dropwise to a pre-prepared precipitating aqueous solution. In this case, the precipitating solution is stirred at a temperature of about 20-25 ° C.

When a drop of said initial aqueous solutions is immersed in said precipitating solution in the droplet volume, diffusion of calcium ions and ion cross-linking of the gel-forming polyelectrolytes containing carboxyl groups with divalent calcium ions quickly occur, resulting in the formation of a strong gel forming a microsphere containing water or an aqueous solution of the desired composition, which in the future can serve as the core of a microcapsule containing water or an aqueous solution.

Thus obtained water-containing microspheres cannot be used as an independent fire extinguishing agent, since without the main shell they quickly lose water and stick together during storage, and also lose flowability, which is the most important property for such a practical application,

According to the invention, in methods of microencapsulation of water or aqueous solutions to obtain a microcapsule having a main shell that prevents the evaporation of water from the core, around the obtained water-containing microsphere placed in the precipitating solution, the main shell of the microcapsule is formed simultaneously with the formation of the microsphere.

In this case, a slower process of diffusion of high molecular weight first and second co-components, which form the main shell and are polyelectrolytes carrying opposite charges towards each other, proceeds. The duration of the process of formation of the main shell is limited by the diffusion rates of the first co-components of the main shell from the formed water-containing microsphere and the second co-components of the main shell from the precipitating solution to the surface layer of the formed water-containing microsphere, in which interaction (complexation) occurs between the first and second co-components with the formation of a gel-containing water-containing microsphere the main shell of the microcapsule, which prevents evaporation during dy from the core.

The process of forming the main shell of the microcapsule lasts about 1-2 hours, then it spontaneously stops, since the formed main shell prevents further diffusion of these co-components. This method of forming the shell allows you to get the main shell of the minimum required thickness, which prevents the evaporation of water from the water-containing core of the microcapsule.

The obtained microcapsules having a core in the form of a microsphere containing gelled water or gelled aqueous solution, and the main shell surrounding the microsphere, are separated by filtration, treated with an anti-caking agent and placed in a tightly closed container, dried from moisture, for storage. Microcapsules are ready for use, for example, for extinguishing or cooling overheated objects.

According to the methods of microencapsulation of water or aqueous solutions according to the invention, the microcapsule obtained in the above manner containing water or an aqueous solution may be provided with an external additional lyophilic membrane located on the surface of the main membrane.

To form the outer additional lyophilic shell, immersion of microcapsules already having the main shell is used in an organic medium containing organic volatile liquid, into which the second co-components suitable for forming the additional shell with lyophilic properties are introduced, preferably polyisocyanate or its mixture with toluene diisocyanates.

In the first embodiment of the third method, as the first juice component for the formation of an additional lyophilic shell, trace amounts of water remaining on the outer surface of the main shell after microcapsules are separated from the dispersion by filtration are used, and the first and second juice components of the additional shell interact in an organic medium in the presence of a catalyst, preferably in the form of dispersed, but not soluble in organic liquids, such as phospholene. In this embodiment, an additional outer lyophilic membrane of the obtained microcapsules will be formed by polycarbodiimides.

In the second embodiment of the third method according to the invention, as the first juice components for the formation of an additional lyophilic coating, hexamethylenediamine or polyethylene polyamine and / or other di- and polyamines, soluble in water, are additionally introduced into the initial solution prepared as in the first embodiment of the second method, and as a result interaction of these first and second co-components (polyisocyanate or its mixture with toluene diisocyanates) an additional lyophilic membrane will be formed (without phospholene), forming polyurea.

The mechanism of formation of an additional shell is as follows.

Under the conditions of the first variant of the third microencapsulation method, the phospholene catalyst, in contact with the surface of the microcapsules, on which there are trace amounts of water, dissolves in them and catalyzes the reaction of these trace amounts of water with di- and polyisocyanates diffusing to the surface of the microcapsule from the specified organic medium, and the result Such an interaction is the formation of a polycarbodiimide shell on the surface of the main shell of the microcapsule.

Under the conditions of the second variant of the third microencapsulation method, if the water-containing microsphere and other, in addition to water, first juice components of the additional shell, di- and polyamines, react on the surface of the microcapsule, they also react with the second juice components of the additional shell, di- and polyisocyanates, with the formation polyurea membrane. In this case, the organic medium with microcapsules placed in it is stirred at a temperature of about 20-25 ° C.

As an additional shell forms, it creates an obstacle for the diffusion of the first and second co-components towards each other, and the process stops. Thus, the process of obtaining an additional shell is carried out to obtain a thickness that is minimally necessary to ensure lyophilization of the surface of the microcapsule.

Then, the obtained microcapsules having the main and additional shells are washed with a solution of the same organic medium, preferably carbon tetrachloride or dimethyl carbonate, the microcapsules are separated by filtration and placed in a tightly closed storage container.

Methods of microencapsulation of water or aqueous solutions according to the present invention, providing the formation of a microcapsule core in the form of a single microsphere, in which water or an aqueous solution of the desired composition are placed in a bound gel state, as well as providing for the formation of a primary and secondary shells around a water-containing core with the minimum required thickness, allow to obtain microcapsules of monodisperse composition in the range of sizes (diameters) from 0.25 to 5.0 mm with a high water content, which is practical nical not be obtained when using other known methods for the preparation of water-containing microcapsules, for example spray technology or a double emulsification.

Using the methods of microencapsulation of water or aqueous solutions according to the invention allows to obtain microcapsules of a given diameter, which can be achieved by using droplets or needles having an appropriate hole diameter to form droplets.

Microcapsules containing water or an aqueous solution obtained by microencapsulation of water or aqueous solutions according to the invention can have a distribution of 90-100% over a given diameter and at the same time contain 90-96% of water in the mass of the microcapsules.

Methods for microencapsulation of water or aqueous solutions according to the invention are characterized by low energy consumption, virtually no wastewater, environmental safety and short time of the process of obtaining water-containing microcapsules, which generally determines their economic feasibility.

The following are examples of the method of microencapsulation of water or aqueous solutions according to the invention to obtain various finished products:

- examples 1-4, which show the main options for producing nuclei of microcapsules - water-containing microspheres (to compare their properties with microcapsules containing microspheres as the core of microcapsules);

- examples 5-10, which describe options for producing microcapsules with a core in the form of an aqueous microsphere placed in the shells, including:

- examples 5-7 obtain microcapsules having a main shell,

- examples 8-10 obtain microcapsules having a primary and secondary shell.

Obtained in examples 1-4 water-containing microspheres and obtained in examples 5-10 microcapsules were subjected to the following tests:

Test A:

Distribute microspheres or microcapsules with a layer thickness of 5.0 mm in an open Petri dish and observe the weight loss at a temperature of 20-22 ° C during the day. (This test was introduced for comparison purposes only and is not used to evaluate product stability).

Test B:

100 g of microspheres or microcapsules are placed in a tightly closed glass container and the appearance of exudate and adhesion are monitored for a month.

Example 1. Obtaining water-containing microspheres (without shells)

The initial aqueous solution is obtained by adding 4.0 g of sodium alginate to 96.0 ml of distilled water and dissolving it with stirring for 4-5 hours at a temperature of 20-25 ° C.

A precipitating solution is obtained consisting of 150 ml of a 2.5% aqueous solution of calcium dichloride.

The specified initial solution is introduced dropwise into the precipitating solution.

The formed water-containing microspheres containing an aqueous solution, gelled with the sodium alginate molecules contained therein, crosslinked with divalent calcium ions contained in the precipitating solution, are kept in the precipitating solution with stirring for about 20 minutes. Then the microspheres are separated by filtration, washed with water and placed in a tightly closed container.

The diameter of the obtained aqueous microspheres 2.0 mm, the water content of 96% by weight.

The microspheres when tested in test A lose 28% by weight, in test B exudation and coalescence of particles are observed.

Example 2. Obtaining water-containing microspheres (without shells)

The initial aqueous solution is obtained by adding 8.0 g of sodium alginate to 92.0 ml of distilled water and dissolving it with stirring for 4-5 hours at a temperature of 20-25 ° C.

A precipitating solution is obtained consisting of 150 ml of a 2.5% aqueous solution of calcium dichloride.

The specified initial solution is introduced dropwise into the precipitating solution.

The formed water-containing microspheres containing an aqueous solution, gelled with sodium alginate molecules contained therein, crosslinked with divalent calcium ions contained in the precipitating solution, are kept in the precipitating solution with stirring for about 20 minutes, the obtained microspheres are filtered off, washed with water and placed in a tightly closed tara.

The diameter of the obtained water-containing microspheres is 5.0 mm, the water content is 90% by weight.

The microspheres when tested in test A lose 24% by weight, in test B exudation and adhesion of particles are observed.

Example 3. Obtaining water-containing microspheres (without shells)

An initial aqueous solution is obtained by adding 4.0 g of pectin to 96.0 ml of distilled water and dissolving it under stirring for 4-5 hours at a temperature of 20-25 ° C.

A precipitating solution is obtained consisting of 150 ml of a 2.5% aqueous solution of calcium dichloride.

The specified initial solution is introduced dropwise into the precipitating solution.

The formed water-containing microspheres containing an aqueous solution, gelled with pectin molecules contained therein, crosslinked with divalent calcium ions contained in the precipitating solution, are kept in the precipitating solution with stirring for about 20 minutes. Then the microspheres are separated by filtration, washed with water and placed in a tightly closed container.

The diameter of the obtained aqueous microspheres 2.0 mm, the water content of 96% by weight.

The microspheres when tested in test A lose 28% by weight, in test B exudation and coalescence of particles are observed.

Example 4. Obtaining water-containing microspheres (without shells)

An initial aqueous solution is obtained by adding 98% by weight of distilled water to 2.0 g of gum arabic and dissolving it under stirring for 4-5 hours at a temperature of 20-25 ° C.

A precipitating solution is obtained consisting of 150 ml of a 4.0% aqueous calcium dichloride solution.

The specified initial solution is introduced dropwise into the precipitating solution.

The formed water-containing microspheres containing an aqueous solution, gelled with pectin molecules contained therein, crosslinked with divalent calcium ions contained in the precipitating solution, are kept in the precipitating solution with stirring for about 20 minutes. Then the microspheres are separated by filtration, washed with water and placed in a tightly closed container.

The diameter of the obtained water-containing microspheres is 0.25 mm, the water content is 94% by weight.

The microspheres when tested in test A lose 28% by weight, in test B exudation and coalescence of particles are observed.

Example 5. Obtaining microcapsules containing an aqueous solution having a main shell on the surface of aqueous microspheres

The initial aqueous solution is obtained by adding 3.0 g of sodium alginate to 96.0 ml of distilled water and dissolving it with stirring for 4-5 hours at a temperature of 20-25 ° C. Then, 1.0 g of cellulose acetate phthalate is dissolved in the resulting solution with stirring for 2-3 hours at a temperature of 20-25 ° C.

A precipitating solution is obtained by dissolving 2.25 g of chitosan in 150 ml of distilled water with stirring for 2–3 hours at a temperature of 20–25 ° C, and then 3.75 g of calcium dichloride are introduced and dissolved with stirring for 30–40 minutes.

The initial solution is added dropwise to the precipitating solution, the obtained microcapsules are kept in the bath for 1.0-2.0 hours with stirring, the liquid phase is separated on the filter, the microcapsules are washed with water, ensuring its complete flow off.

The microcapsules are then treated with an anti-caking agent (aerosil) and placed in a tightly closed container for storage.

The properties of the microcapsules: the diameter of the microcapsules is 1.5 mm, the water content is 91% by weight.

When testing microcapsules: according to test A, the loss of water was not more than 4% by mass; when testing according to test B, exudate was not released, particles did not stick together. The flowability, determined by the method of slope angle, was 32-34 degrees, which indicates a good flowability of the product.

Weight loss during storage for six months in a tightly closed container is not observed.

These data indicate the stability of the obtained microcapsules subject to the storage conditions in a closed container until the time of intended use.

Example 6. Obtaining microcapsules containing water, having a main shell on the surface of water-containing microspheres

The same sequence of techniques is performed as in Example 5, with the difference that pectin is used instead of sodium alginate.

The properties of the obtained microcapsules: the diameter of the microcapsules is 4.0 mm, the water content is 96% by weight.

When testing microcapsules: according to test A, the water loss was not more than 4% by weight; when testing according to test B, exudate is not secreted, particles do not stick together. The flowability, determined by the method of slope angle, was 32-34 degrees, which indicates a good flowability of the product.

Weight loss during storage for six months in a tightly closed container is not observed.

These data indicate the stability of the obtained microcapsules subject to the storage conditions in a closed container until the time of intended use.

Example 7. Obtaining microcapsules containing water, having a main shell on the surface of water-containing microspheres

The same sequence of steps is performed as in Example 5, with the difference that 2.25 g of polyvinylpyrrolidone is introduced into the precipitating solution instead of chitosan, and 3.0 g of sodium alginate and 1 are added to obtain the initial aqueous solution in 97.0 ml of distilled water. , 0 g of polyacrylic acid.

Properties of the obtained microcapsules: the diameter of the microcapsules is 0.25 mm, the water content is 90% by weight.

When testing microcapsules: according to test A, the water loss was not more than 4% by weight; when testing according to test B, exudate is not secreted, particles do not stick together. The flowability, determined by the method of slope angle, was 32-34 degrees, which indicates a good flowability of the product.

Weight loss during storage for six months in a tightly closed container is not observed.

These data indicate the stability of the obtained microcapsules subject to the storage conditions in a closed container until the time of intended use.

Example 8. Obtaining microcapsules having a primary and secondary shell

To 30.0 g of microcapsules having a base coat containing cellulose acetate phthalate and chitosan prepared as in Example 5, 50.0 ml of carbon tetrachloride (CCl ₄ ) are added, a stirrer is added and 0.36 ml of phospholene are introduced. The resulting mixture was stirred for 10-15 minutes, then 3.0 g of polyisocyanate dissolved in 10 ml of CCl _{4 were} gradually added. Stirring is continued for 3 hours at a temperature of 20-25 ° C. At the end of the process, the liquid phase is separated on the filter, the microcapsules are washed 1 time with CCl ₄ , filtered and dried for about 30 minutes in a fume hood. After this, the microcapsules are placed in a tightly closed container.

When testing microcapsules: according to test A, the loss of water was not more than 3.9% by mass, while testing according to test B, exudate was not released, particles did not stick together. The flowability, determined by the method of slope angle, was 32-34 degrees, which indicates a good flowability of the product.

Example 9. Obtaining microcapsules having a primary and secondary shell

The method is carried out similarly to that described in example 8, but in the precipitating solution instead of 3 g of polyisocyanate, a mixture of polyisocyanate (2.1 g) with toluene diisocyanate (0.9 g) is used, that is, in the ratio of 70% by weight to 30% by weight.

When testing microcapsules: according to test A, the loss of water was not more than 4% by mass; when testing according to test B, exudate was not released, particles did not stick together. The flowability, determined by the method of slope angle, was 32-34 degrees, which indicates a good flowability of the product.

Example 10. Obtaining microcapsules having a primary and secondary shell

An initial aqueous solution is obtained by adding 3.0 g of sodium alginate to 96.0 ml of distilled water and dissolving it with stirring for 4-5 hours at a temperature of 20-25 ° C, then 1.0 g of cellulose acetate is dissolved in the resulting solution. with stirring for two to three hours at a temperature of 20-25 ° C. Next, the first juice components of the additional shell are introduced, preferably 0.5-1.0 g of hexamethylenediamine or polyethylene polyamine, with stirring for 25-30 minutes.

A precipitating solution is obtained by dissolving 2.25 g of chitosan in 150 ml of distilled water with stirring for 2–3 hours at a temperature of 20–25 ° C, and then 3.75 g of calcium dichloride is added and dissolved with stirring for 30–40 minutes.

The initial solution is added dropwise to the precipitating solution, the obtained microcapsules are kept in the bath for 1.0-2.0 hours with stirring, the liquid phase is separated on the filter, the microcapsules are washed with water, ensuring its complete drainage.

To 30.0 g of the microcapsules obtained by the described method, 50.0 ml of carbon tetrachloride (CCl ₄ ) was added, the stirrer was turned on and 3.0 g of polyisocyanate dissolved in 10 ml of CCl _{4 was} gradually added. Stirring is continued for 3 hours at a temperature of 20-25 ° C. At the end of the process, the liquid phase is separated on the filter, the microcapsules are washed 1 time with CCl ₄ , filtered and dried for about 30 minutes in a fume hood.

When testing the obtained microcapsules: according to test A, the water loss was not more than 4% by mass; when testing according to test B, exudate was not released, particles did not stick together. The flowability, determined by the method of slope angle, was 32-34 degrees, which indicates a good flowability of the product.

According to the test results of the microcapsules obtained in examples 8-10, it can be concluded that the obtained microcapsules having a main and additional shell did not show significant changes in properties compared to the microcapsules obtained in examples 6-7, however, the nature of their surface changed to the side increase lyophilicity.

These properties were confirmed by determining the contact angles of the obtained microcapsules. The measurement results of the wetting angle of the microcapsules are shown in the table.

Microcapsules according to example No. Values of the contact angle (in degrees) liquid siloxane epoxy resin 6 47.16 68.90 (microcapsule having a core in the form of a microsphere located inside the main shell) 9 42.27 55.25 (microcapsule having a core in the form of a microsphere placed inside the main shell, and an additional outer shell)

Thus, the formation on the outer surface of the main shell of the microcapsules according to the invention of an additional lyophilic shell allows the use of the microcapsules according to the invention as fillers that reduce the susceptibility of polymer materials to fire, for example, as fillers of polymer compounds of reduced combustibility.

The above examples of microencapsulation methods according to the invention do not limit the possibilities of implementing the present invention, not beyond the scope of patent claims.

The microencapsulation methods according to the invention are not limited to the described compositions of the options for additional shells and make it possible to control the properties of microcapsules containing water, for example, the lyophilicity of the shells, for use in the preparation of various compounds depending on the nature of the polymer matrices used.

Microcapsules according to the invention, containing water or aqueous solutions obtained by the methods according to the invention, are resistant to temperature influences under conditions of storage in closed containers, for a long time ensure water preservation inside the microcapsules, their flowability and readiness for intended use as a fire extinguishing or cooling agent.

The microencapsulation methods developed according to the invention with lyophilization of the surface of the microcapsules by forming additional shells open up the possibility of their use as fillers of polymer compounds of reduced combustibility.

Aqueous solutions and suspensions in microencapsulated form can find application in the creation of new bioactive drugs, drugs, live microbiological cultures, for example, for programmable protection of them from the environment or for prolonging their action, in the food industry and other industries.

Professionals in the field of physical chemistry of polymers and microencapsulation should understand that various improvements and improvements can be made to the microcapsules according to the invention and methods for their preparation, without departing from the scope of patent claims. For example, the compositions of the primary and secondary membranes can be selected from juice components suitable for contact with, for example, acidic or alkaline or other aggressive media, or can be modified for the programmed release of water or an aqueous solution contained in microcapsules under specified operating conditions at a given speed.

The microcapsules according to the invention containing water or aqueous solutions, and the method of microencapsulation of water or aqueous solutions according to the invention can be implemented using known techniques and known substances. Microcapsules containing water or aqueous solutions, in addition to using chemical and atomic reactors, electronic equipment to solve the main problems of fighting fires and emergency overheating, can find application in technologies for producing polymer compounds filled with microencapsulated water to reduce their combustibility, as well as in food and pharmaceutical industries and other industries.

Claims (21)

1. A microcapsule containing water or an aqueous solution, gelled with crosslinked calcium ions dissolved in said water or an aqueous solution, gelling polyelectrolytes having carboxyl groups, characterized in that said water or aqueous solution contains in the form of a single isolated water-containing microsphere having a predetermined diameter , on the outer surface of which in the interphase layer a solid spherical, equally thick main shell is formed, which has hydrophilic properties and has a thickness and density of mounds minimally necessary to prevent the evaporation of water contained in the microsphere, while the main shell is formed by macromolecules of complex compounds obtained by counter diffusion into the interphase layer of high molecular weight first components that are carriers of a negative charge and high molecular weight second co components that are carriers of a positive charge. 2. A microcapsule containing water or an aqueous solution, gelled with crosslinked calcium ions dissolved in said water or an aqueous solution, gelling polyelectrolytes having carboxyl groups, characterized in that said water or aqueous solution contains in the form of a single isolated water-containing microsphere having a predetermined diameter on the outer surface of which in the interphase layer a solid spherical, equally thick main shell is formed, having hydrophilic properties and having a thickness and density of mounds minimally necessary to prevent the evaporation of water contained in the microsphere, while the main shell is formed by macromolecules of complex compounds obtained by counter diffusion into the interfacial layer of high molecular weight first components that are carriers of a negative charge and high molecular weight second co components that are carriers of a positive charge, and while on the outer surface of the specified main shell formed an additional outer spherical equally thick about span of having lyophilic properties. 3. The microcapsule according to claim 1 or 2, characterized in that it contains the indicated water or aqueous solution in an amount of not less than 90% by weight of the microspheres having a given diameter, selected in the range from 0.25 to 5.0 mm. 4. The microcapsule according to claim 1 or 2, characterized in that it contains water or an aqueous solution gelled with sodium alginate and / or pectin and / or gum arabic and / or any other polysaccharides containing carboxyl groups and crosslinked by calcium ions . 5. The microcapsule according to claim 1 or 2, characterized in that the main shell is formed by macromolecules of complex compounds obtained by counter diffusion and interaction of cellulose acetate phthalate with chitosan. 6. The microcapsule according to claim 1 or 2, characterized in that the main shell is formed by macromolecules of complex compounds obtained by counter diffusion and the interaction of polyacrylic acid with polyvinylpyrrolidone. 7. The microcapsule according to claim 2, characterized in that the additional outer shell is formed by polycarbodiimides. 8. The microcapsule according to claim 2, characterized in that the additional outer shell is formed by polyurea. 9. The method of microencapsulation of water or aqueous solutions to obtain separate aqueous microspheres containing water or an aqueous solution, gelled using polyelectrolytes and crosslinked by calcium ions, comprising the following steps:
a) obtaining a starting aqueous solution containing at least gelling polyelectrolytes dissolved in water: sodium alginate and / or pectin and / or gum arabic and / or any other polysaccharides containing carboxyl groups;
b) obtaining a precipitating aqueous solution containing a source of divalent calcium ions dissolved in it, using aqueous solutions of calcium dichloride and / or calcium lactate and / or calcium glycerophosphate and / or any other water-soluble calcium salts;
c) introducing the initial aqueous solution obtained in step a) into the precipitating aqueous solution obtained in step b) with drops having a predetermined volume, providing microspheres having a predetermined diameter, selected in the range from 0.25 to 5.0 mm while stirring the precipitating solution at a temperature of 20-25 ° C for a time sufficient to form a dispersion in the precipitating solution containing isolated microspheres with a monodispersity of at least 90%, in which the initial aqueous solution is in the form of a gel formed gel yuschimi polyelectrolytes obtained in step a), cross-linked by divalent calcium ions obtained in step b);
d) isolating the microspheres obtained in step c) from the dispersion of the precipitating solution by filtration;
e) the placement of the obtained microspheres in containers dried from moisture. 10. A method of microencapsulation of water or aqueous solutions to obtain a microcapsule containing water or an aqueous solution in the form of a single isolated water-containing microsphere having a predetermined diameter, on the outer surface of which a solid spherical, equally thick main shell having hydrophilic properties and having a thickness and density is formed shells minimally necessary to prevent evaporation of water contained in the microsphere, comprising the following steps:
a) obtaining a starting aqueous solution containing at least gelling polyelectrolytes dissolved in water: sodium alginate and / or pectin and / or gum arabic and / or any other polysaccharides containing carboxyl groups and high molecular weight first co-components of the main shell of the microcapsule being carriers of a negative charge;
b) obtaining a precipitating solution containing dissolved in water, at least one source of divalent calcium ions and high molecular weight second co-components that are carriers of a positive charge;
c) introducing the initial aqueous solution obtained in step a) into the precipitating solution obtained in step b) with droplets having a predetermined volume, providing microspheres having a predetermined diameter, selected in the range from 0.25 to 5.0 mm, while stirring the precipitating solution at a temperature of 20-25 ° C for a time sufficient to form a dispersion in the precipitating solution containing isolated microspheres of a given diameter with a monodispersity of at least 90%, in which the initial aqueous solution is in the form of a gel, Rowan gelling polyelectrolytes obtained in step a), cross-linked by divalent calcium ions obtained in step b);
d) holding the dispersion obtained in step c) at a temperature of 20-25 ° C for a time sufficient to form microcapsules having one microsphere obtained in step c) provided on the surface with a main shell formed by macromolecules of complex compounds obtained with using counter diffusion into the interphase layer of the high molecular weight first co-components of the main shell obtained in step a) and second co-components of the main shell obtained in step b);
e) isolating the microcapsules obtained in step d) from the precipitating solution by filtration;
f) washing with water the microcapsules obtained in step e) and drying them in air;
g) treating the microcapsules obtained in step f) with an anti-caking agent;
h) placing the obtained microcapsules in a tightly closed container, dried from moisture,
and at the same time, aqueous solutions of calcium dichloride, and / or calcium lactate, and / or calcium glycerophosphate, and / or any other water-soluble calcium salts are used as a source of divalent calcium ions. 11. The method according to claim 10, characterized in that cellulose acetate phthalate is used as the first juice components of the main shell, and chitosan is used as the second juice components of the main shell. 12. The method according to claim 10, characterized in that polyacrylic acid is used as the first juice components of the main shell, and polyvinylpyrrolidone is used as the second juice components of the shell base. 13. The method according to claim 10, characterized in that the microcapsules with a monodispersity of at least 90% are obtained in the range of diameters from 0.25 to 5.0 mm and containing water or an aqueous solution in an amount of at least 90% by weight of the microcapsule. 14. The method of microencapsulation of water or aqueous solutions to obtain a microcapsule containing gelled water or an aqueous solution in the form of a single isolated water-containing microsphere having a predetermined diameter, on the outer surface of which a solid spherical uniform thickness main shell having hydrophilic properties and having a thickness and the density of the shell, the minimum necessary to prevent the evaporation of water contained in the microsphere, and containing formed on the main shell an additional outer shell having lyophilic properties and formed by polycarbodiimides, comprising the following steps:
a) obtaining a starting aqueous solution containing at least gelling polyelectrolytes dissolved in water: sodium alginate and / or pectin and / or gum arabic and / or any other polysaccharides containing carboxyl groups and high molecular weight first co-components of the main shell of the microcapsule being carriers of a negative charge;
b) obtaining a precipitating solution containing dissolved in water, at least one source of divalent calcium ions and high molecular weight second co-components that are carriers of a positive charge;
c) introducing the initial aqueous solution obtained in step a) into the precipitating solution obtained in step b) with droplets having a predetermined volume, providing microspheres having a predetermined diameter, selected in the range from 0.25 to 5.0 mm, while stirring the precipitating solution at a temperature of 20-25 ° C for a time sufficient to form a dispersion in the precipitating solution containing isolated microspheres of a given diameter with a monodispersity of at least 90%, in which the initial aqueous solution is in the form of a gel, Rowan gelling polyelectrolytes obtained in step a), cross-linked by divalent calcium ions obtained in step b);
d) holding the dispersion obtained in step c) at a temperature of 20-25 ° C for a time sufficient to form microcapsules having a microsphere core obtained in step c) provided on the surface with a main shell formed by macromolecules of complex compounds, obtained by counter diffusion into the interfacial layer of the high molecular weight first co-components of the main shell obtained in step a) and second co-components of the main shell obtained in step b);
e) isolating from the dispersion treated in step d) by filtering the microcapsules obtained in step d) and containing trace amounts of water on the outer surface of the main shell as the first juice component to form the outer additional shell;
f) obtaining a liquid organic medium into which the second co-components are introduced to form an outer additional shell having lyophilic properties and a liquid catalyst soluble in water but not soluble in organic liquids;
g) introducing the microcapsules obtained in step e) into the organic medium obtained in step f) with stirring to obtain a dispersion of said microcapsules in said organic medium;
h) holding the dispersion obtained in step g) at a temperature of 20-25 ° C for a time sufficient to form on the outer surface of the microcapsules contained in the dispersion obtained in step g) an additional external lyophilic membrane when these first co-components interact with the additional shells in the form of trace amounts of water obtained in step e), with second co-components of the additional shell obtained in step f), in the presence of said catalyst;
i) isolating the microcapsules obtained in step h) from the organic medium by filtration;
k) washing the microcapsules obtained in step i) with the same organic volatile liquid as used in step f);
l) placing the microcapsules obtained in step k) in a tightly closed container, drained of moisture,
and wherein:
- as a source of divalent calcium ions using aqueous solutions of calcium dichloride, and / or calcium lactate, and / or calcium glycerophosphate, and / or any other water-soluble calcium salts,
- as a liquid organic medium in step f) carbon tetrachloride or dimethyl carbonate is used,
- phospholene, preferably 1-oxo-1,3-dimethylphospholene, is used as a catalyst,
- as the second juice components of the additional outer shell using a polyisocyanate or a mixture of polyisocyanate with toluene diisocyanates. 15. The method according to 14, characterized in that cellulose acetate phthalate is used as the first juice components of the main shell, and chitosan is used as the second juice components of the main shell. 16. The method according to 14, characterized in that polyacrylic acid is used as the first juice components of the main shell, and polyvinylpyrrolidone is used as the second juice components of the shell base. 17. The method according to 14, characterized in that receive microcapsules with a monodispersity of at least 90% in the range of diameters from 0.25 to 5.0 mm, containing water or an aqueous solution in an amount of at least 90% by weight of the microcapsule. 18. The method of microencapsulation of water or aqueous solutions to obtain a microcapsule containing gelled water or an aqueous solution in the form of a single isolated water-containing microsphere having a predetermined diameter, on the outer surface of which a solid spherical uniform thickness main shell having hydrophilic properties and having a thickness and the density of the shell, the minimum necessary to prevent the evaporation of water contained in the microsphere, and containing formed on the main shell an additional outer shell with lyophilic properties and formed by polyureas, including the following steps:
a) obtaining an initial aqueous solution containing at least gelling polyelectrolytes dissolved in water having carboxyl groups, high molecular weight first co-components of the main shell having a negative charge, and first co-components to form an additional outer shell;
b) obtaining a precipitating solution containing dissolved in water, at least one source of divalent calcium ions and high molecular weight second co-components of the main shell having positive charges;
c) introducing the initial aqueous solution obtained in step a) into the precipitating solution obtained in step b) with droplets having a predetermined volume, providing microspheres having a predetermined diameter, selected in the range from 0.25 to 5.0 mm, while stirring the precipitating solution at a temperature of 20-25 ° C for a time sufficient to form a dispersion in the precipitating solution containing isolated microspheres of a given diameter with a monodispersity of at least 90%, in which the initial aqueous solution is in the form of a gel, Rowan gelling polyelectrolytes obtained in step a), cross-linked by divalent calcium ions obtained in step b);
d) holding the dispersion obtained in step c) at a temperature of 20-25 ° C for a time sufficient to form microcapsules having one microsphere obtained in step c) provided on the surface with a main shell formed by macromolecules of complex compounds obtained with using counter diffusion into the interphase layer of the high molecular weight first co-components of the main shell obtained in step a) and second co-components of the main shell obtained in step b);
e) isolating from the dispersion treated in step d) by filtering the microcapsules obtained in step d) and containing trace amounts of water on the outer surface of the main shell;
f) obtaining a liquid organic medium into which the second juice components are introduced to form an outer additional shell having lyophilic properties;
g) introducing the microcapsules obtained in step e) into the organic medium obtained in step f) with stirring to obtain a dispersion of said microcapsules in said organic medium;
h) holding the dispersion obtained in step g) at a temperature of 20-25 ° C for a time sufficient to form on the outer surface of the microcapsules contained in the dispersion obtained in step g) an additional external lyophilic membrane when these first co-components interact with the additional the shell obtained in step a), with the second co-components of the additional shell obtained in step f);
i) isolating the microcapsules obtained in step h) from the organic medium by filtration;
k) washing the microcapsules obtained in step i) with the same liquid organic medium as that used in step f);
l) placing the microcapsules obtained in step k) in a tightly closed container, drained of moisture,
and wherein:
- as a source of divalent calcium ions using aqueous solutions of calcium dichloride, and / or calcium lactate, and / or calcium glycerophosphate, and / or any other water-soluble calcium salts,
- as a liquid organic medium in step f) carbon tetrachloride or dimethyl carbonate is used,
- as the first juice components of the additional outer shell use hexamethylenediamine, or polyethylene polyamine, and / or other di- and polyamines, soluble in water,
- and as the second juice components of the additional outer shell, a polyisocyanate or a mixture of polyisocyanate with toluene diisocyanates is used. 19. The method according to p. 18, characterized in that the cellulose acetate phthalate is used as the first juice components of the main shell, and chitosan is used as the second juice components of the main shell. 20. The method according to p. 18, characterized in that polyacrylic acid is used as the first juice components of the main shell, and polyvinylpyrrolidone is used as the second juice components of the main shell. 21. The method according to p. 18, characterized in that microcapsules with a monodispersity of not less than 90% are obtained in the range of diameters from 0.25 to 5.0 mm, containing water or an aqueous solution in an amount of not less than 90% by weight of the microcapsule.