RU2734607C1 - Apparatus for producing composite hydrogel material particles - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of composite hydrogel material particles. Technical result is achieved by installation for production of particles of composite hydrogel material, which comprises reactor with low-speed mixing device and heating jacket, unit for coarse grinding of briquetted hydrogel, unit of dispersion on special screen and unit of suspension separation into small fractions. Plant additionally contains unit of high-speed top-wheel grinding in the form of high-speed toothed disc cutter or knife cross-shaped mill with knives. Outside the reactor there are installed: a device for lowering and lifting of cutters, a dispersing unit containing a pump for transfer of suspensions, a two-zone dispersant, made in the form of a cylindrical housing with a cylinder-conic piston in it having conical surfaces made with guide grooves and equipped with a distribution ring with partitions and a mesh filter. Listed devices are installed in series and connected by system of pipelines for withdrawal of suspensions with coarse particles to unit for dispersion and return of milled hydrogel to reactor for re-dispersion.

EFFECT: technical result is higher efficiency and specific capacity of installation and possibility of performing gel formation, polymerisation and primary crushing in one apparatus with minimum operations.

1 cl, 7 dwg, 1 tbl, 4 ex

Description

The present invention relates to the field of making hydrogels of various natures that can be used in the food industry (in particular, in the confectionery industry), in the paint and varnish and paper industries, in medicine and in agriculture.

For example, the food industry uses a multistage technology for the production of Muesli bars, which are a hydrogel product with a grain filler, the first stage of which is carried out in an apparatus with a stirrer, and the second stage in an apparatus with rollers. To do this, at the beginning of the process, grain components (seeds, oatmeal, corn, buckwheat) are poured into an apparatus with a stirrer, for example, a frame type, mixed, poured with honey, thickeners are poured and mixed again. In this case, the resulting mass is plasticized and passes into a pasty state. Then the product in the form of a hydrogel is loaded into an apparatus with rollers, and after rolling a layer of confectionery mass is obtained. After that, the mass is manually cut with special knives into pieces of specified sizes and shapes [RU 2270581, A23L 1/10, 2006].

It is known that a number of industries use various hydrogels based on cellulose derivatives, as well as polyurethane and polyacrylic hydrogels. But polyacrylamide hydrogels have received the greatest application due to the simplicity and cost-effectiveness of their preparation, reduced adhesive characteristics, in particular stickiness. Polymer acrylic hydrogels are used in a number of areas, for example, in plant growing to improve the water regime of the soil [RU 2189382, S09K 17/40, 20.09.2002]. In this case, an acrylic polymer is used as a filler into which the clay material is introduced. Polyacrylamide hydrogels, due to their high porosity, are also used as a carrier of immobilized biologically active substances in medicine [RU 249317, C08F 120/56, 2013]. The hydrogel material is also used in the manufacture of paper containing security markers. In this case, the hydrogel material in the form of an aqueous suspension containing security markers is introduced into the pulp suspension and embedded in the paper structure. ["Composite materials based on acrylamide hydrogel to protect the authenticity of securities" // All materials. Encyclopedic reference book, No. 3, 2016; RU 2536215, B4M5 / 124, 2014]. Methods for obtaining polyacrylamide hydrogels are widely described in previously published information sources [Research Methods in Immunology, ed. I. Lefkovits and B. Pernis, Mir, Moscow, p. 99 - 107; RU 2067873, A61F 2/02, 1995; RU 249317, C08F 120/56, 2013; RU 2031097, B01J 19/00, 1995; RU 2076873, C08F 120/56, 1997].

So, in the known method of producing powdered polyamide polymers, a powdered acrylamide polymer is obtained by radical polymerization of acrylamide in a concentrated aqueous solution in the presence of salts of mono and disubstituted carbonic acid and a chemical initiator and further grinding the obtained gel-like polymer, additional drying followed by crushing [RU 2076873, C08F 56, 1997]. According to this method, the process is carried out first in a reactor equipped with a stirrer and a nitrogen sparger. In this case, the reaction mixture is purged with nitrogen for 30 minutes and deoxygenated solutions of potassium persulfate are introduced. The initial polymerization temperature is 25 ° C. After two hours of polymerization, the temperature reaches 84 ° C. The resulting gelled polymer block is removed through the bottom of the reactor and cut into pieces of 20x20x70 mm. Then these elements are loaded into a grinder with an outlet grid of 2 mm and after passing through it, gel-like polymer particles with a size of 2x5x10 mm are obtained. The resulting polymer particles are dried in a belt dryer with hot air at t = 65 ° C. The dry particles are then crushed to a size of less than 1.4 mm. However, this method using the specified equipment fails to obtain a homogeneous granular micron-sized hydrogel.

It was revealed that the structural design of the process of obtaining a fine-grained hydrogel product has a significant effect on both the polymerization process and the grinding of the hydrogel product.

So it is known that for carrying out the process of polymerization and pasteurization of gel-like products can be used a device that includes a reactor with a frame stirrer [Makarenkov DA, Nazarov VI, Barinsky EA Processes and apparatus of chemical technology. The main processes and equipment for the production of pigments, suspensions and pastes in paints and varnishes. Textbook. allowance. M., Infra-M, 2016.212 s]. Such a reactor is equipped with an external heater (jacket), as well as nozzles for loading the initial components and unloading the finished mixture. The mixer is replaceable, driven by a geared motor and is a welded structure with replaceable blades made of food grade silicone. When rotated, this stirrer mixes the product and provides a non-stick effect to the wall and to the bottom of the apparatus. The machine can be used to cook jelly for 7 days.

The disadvantage of such a reactor is the impossibility, after receiving and polymerization of the hydrogel in the form of a briquette, to remove it from the body and carry out its grinding. To grind the hydrogel block, it is necessary to use a device for transferring the block to the grinding device.

For grinding polymeric materials, for example, a device is used containing a housing with loading and unloading nozzles, in which a stationary cutting unit and a movable cutting unit associated with a rotation drive are located [RU 2005606, В29В 17/00, 1994.].

The cutting units are made in the form of hollow truncated cones located with a gap relative to each other, open from the side of large bases with perforated side walls, and the units are installed with the possibility of axial movement. Grinding of the material in the process under consideration is carried out in an aqueous medium with a ratio of the mass of the material to the mass of the liquid as 0.2: 1.0. However, in the hydrogel suspension obtained by this method, there is a large variation in particle sizes in the finished product. Such a wide distribution of the resulting particles in particle size distribution is a significant disadvantage of this method and the equipment used for its implementation. In addition, this process is rather laborious and uneconomical, since it includes a stage of preliminary grinding of the polymer and it requires carrying out the stages of polymerization in a separate reactor.

A more effective grinding device is a device implemented in the known method for producing a polyacrylic hydrogel [RU 2031097, C08F 120/56, 1995]. The polymerization process in this method is carried out at a special temperature regime (not higher than 70 ° C) and with a special stirring regime. Stirring begins after the start of polymerization and is carried out for 5-15 minutes. The polymerization is carried out in a twin-screw reactor equipped with several paddle stirrers with channels for a liquid cooling agent. As stated in the description of this process, due to these measures it is possible to reduce the formation of crusts in the reactor. The grinding stage in this method is carried out on a special metal mesh (for example, with a hole diameter of 0.297 mm), on which the obtained crosslinked polymer is placed in the form of large pieces of polymer hydrogel and then dried with hot air at 150 ° C for 120 minutes. The dried polymer is passed through a shaking mill and separated on a wire mesh with a hole diameter of 0.84 mm. The dried crosslinked polymer can be further milled by any known method to an average particle size of 5 to 0.05 mm. Preferred grinding is from 1.0 to 0.1 mm.

In another known method, the grinding of the polyacrylamide hydrogel is carried out by forcing it through a sieve with a pore diameter of 1 mm [RU 2493173, C08F 120/56, 2013]. However, this method produces only a hydrogel in the form of large particles.

As mentioned above, the object under consideration, namely, devices for obtaining a composite hydrogel material, are used not only in the chemical industry, but also in the food industry.

For example, as an analogue of the claimed object can be considered a line for the production of grain flakes [JSC "Melkom" [Electronic resource]: URL: http://www.melkom.ru, 2004-2014]. The line contains a gravity separator for cleaning grains from dust, an auger loader that transfers grain onto a conveyor belt passing through an installation with an infrared emitter. After heat treatment of the grains (micronization) in the roller, the grains are flattened. After crushing, the product is classified in a drum classifier, and then packed into packaging.

In another technical solution, a line for the production of muesli is considered, which contains a digester, a kneading machine, a loading conveyor, a unit for rolling the billet onto a tape, a device for calibrating a layer, a refrigerating tunnel, a cutting unit with a guillotine and a unit for packing bars into foil [Abramov N.I. ... Automated complex for preparation "muesli-bar" / Food industry, 2004, No. 4, p. 80]. This line allows you to get calibrated bars of a certain weight.

The process for obtaining granular hydrogel and confectionery mass saturated with fillers and ingredients in the above device proceeds in several stages. In this case, the introduction into the confectionery mass of various ingredients in the form of syrups, molasses and honey during heat treatment translates it into a plasticized state in the form of a briquetted gel.

The closest to the invention in technical essence and the achieved result is a line for the production of muesli bars, protected by a Belarusian patent for a useful model [BY 20060346, 30.05.2006]. The line contains a number of devices interconnected by a system of pipelines and conveyors. The line includes a device for preparing ingredients, an electric cooker for dissolving, boiling and mixing ingredients, a device for forming a blank, slicing (crushing) bars and a device for cooling and packaging. The cooking device contains horizontally placed screws with z-shaped blades, a device for cutting bars, made in the form of a cutting machine with knives. The transfer of products and semi-finished products from device to device is carried out manually or using conveyors.

The line works as follows. The ingredients for the preparation of the syrup according to the recipe are loaded into a jacketed electric cooker mounted on the supports. Electric heating elements provide heating of the bowl, respectively, of its contents to a predetermined temperature (t = 120-140) ° C, controlled by a thermocouple. To mix the ingredients and evenly heat the contents throughout the volume, the mixer is rotated by means of an electric motor and a worm gear. The duration of cooking syrup and the temperature of its heating by electric heating elements are determined in accordance with the technology.

At the end of the cooking process, to stop the mixer, turn off the electric motor and turn off the electric heating elements.

Then the prepared syrup is pumped into the mixer, where it is evenly distributed on the surface of the dry ingredients. The working bodies of the mixer are two horizontally located screws with z-shaped blades, which mix the recipe components and rotate towards each other. The screws are driven into rotation by means of an electric motor and a worm gear. The water jacket, in the process of mixing the recipe components, heats the contents of the container due to the constant circulation of hot water. At the end of the mixing process of the recipe components, the screws are stopped by turning off the electric motor. Then the unloading window at the bottom of the mixer is opened and the finished confectionery mass is unloaded onto the conveyor. It feeds the confectionery mass onto the cooling forming table. It is used to cool the semi-finished product to a given viscosity (consistency). In this case, the mass acquires viscous-plastic properties and after that, at the other end of the forming table, it is rolled out by means of a rolling shaft into a layer of a given thickness, and then it is cut with a circular knife into plates. The resulting blanks are fed into the enrobing machine on a mesh conveyor, where the prepared muesli bars are covered with a chocolate mass. After cooling, the finished bars are fed to the packaging machine.

The disadvantage of such a line is the multistage operation, low-tech and long-term performance of individual operations in different devices, the complexity of devices for crushing a briquette, the lack of the possibility of obtaining dry granular hydrogel particles and the complexity of the process control.

In order to increase the efficiency and specific productivity of the installation used to obtain particles of composite hydrogel material with various fillers and the possibility of carrying out the processes of gelation, polymerization and primary crushing in one apparatus with a minimum of operations, an installation for the production of particles of composite hydrogel material is proposed, containing a reactor with a slow-speed stirring device and a heating jacket, a unit for coarse grinding of briquetted hydrogel, a dispersion unit on a special grid and a unit for dividing the suspension into small fractions, which also contains a high-speed top-drive grinding unit in the form of a high-speed toothed disk cutter or a knife cruciform cutter with knives, and outside the reactor are installed: for lowering and lifting cutters, a dispersion unit containing a pump for pumping suspensions, a two-zone disperser made in the form of a cylindrical body with a cylinder placed in it A ro-conical piston with guide grooves made on its conical surface and equipped with a distribution ring with baffles and a mesh filter, the devices being installed in series and connected by a pipeline system for draining suspensions with large particles into the dispersion unit and returning the crushed hydrogel to the reactor for redispersion.

In the installation, the cross-shaped cutter is made in the form of four cruciform plates, with four triangular knives placed on them from the outer and inner surfaces with the possibility of moving them around the circumference relative to the plates by 45-135 degrees.

The proposed installation contains a reactor with an external heating jacket - 1, a low-speed frame mixer - 2, a high-speed top-drive gear mill - 16 (Fig. 3), a disk cutter - 17 (Fig. 4), a knife cruciform mill - 18 (Fig. 5.) general electric drive for rotation of mixers and cutters - 3, a device for lowering and raising mixers - 6, a screw pump for pumping a suspension with crushed hydrogel from a reactor - 11 and a homogenizer - 14 (Fig. 6) equipped with a mesh filter-15.

FIG. 1 shows an installation for obtaining a finely dispersed hydrogel suspension; in fig. 2 shows the attachment unit of the frame mixer to the drive; in fig. 3 - attachment point of high-speed toothed disk cutter to the universal drive; in fig. 4 - knot of attachment of the disk cutter to the universal drive; in fig. 5 - design of a cross-shaped knife cutter; in fig. 6 is a general view of the homogenizer; in fig. 7 - design of a homogenizer with a particle dispersion control unit.

The solution to this technical problem is carried out due to the fact that the process of mixing, suspension formation, polymerization, hydrogel tablet preparation and primary grinding is carried out in a single technological cycle. This is ensured by the design of interconnected mixing units, grinding units with specially sharpened knives, rotation speeds of a slow-speed mixer, variable rotation speed of disk and knife mills (increasing towards the end of the technological cycle) and the speed of lowering (immersion) of the knives into the tabletted hydrogel mass, associated with the speed ( with time) crosslinking of the polymer.

The final dispersion of the hydrogel particles to micron sizes is achieved in a disperser, where a screw pump 11 pumps the hydrogel suspension at a given pressure through two zones: an annular gap and a mesh filter 15 installed on the pipe.

The plant for the production of particles of composite hydrogel material consists of two blocks. The first block includes a support frame with vertical posts and guides, as well as a vertical reactor with an external heating jacket and a set of replaceable mixing devices. It includes a low-speed frame agitator, a high-speed top-drive gear disc cutter, a cruciform disc cutter, a general electric drive for rotating mixers and cutters, a device for lowering and raising the mixers.

The second block (homogenization unit) contains a screw pump for pumping a suspension with crushed hydrogel from a reactor, a homogenizer equipped with a mesh filter.

Block (1) (Fig. 1) consisting of an apparatus with stirring devices, a stirrer lifting mechanism and a drive for its rotation. The composition of the reactor with mixing devices and cutters includes: 1 - a container with a jacket; 2 - frame mixer; 3 - electric drive for rotation of mixers and cutters; 4 - guides; 5 - base; 6 - device for lowering and raising mixers; 7 - spindle; 8 - control unit; 9 - vertical rack; 10 - lower supports with adjustable legs. The homogenization unit includes a screw pump 11 connected by means of a coupling 12 to a drive 13, a homogenizer 14 and a system of pipes for introducing pre-crushed material and outputting the finished product with a predetermined particle size distribution.

The technical characteristics of the apparatus with a stirrer are shown in Table 1. The mixer designs are shown in FIG. 2, 3, 4, 5.

The electric drive for rotation of mixers and cutters 3 is fixed on a carriage, which moves along the guides 4 of the base 5 in the vertical direction by means of a motor-reducer. The base 5 is attached to a clamp 3, which is attached to a special rack 9. The agitator shaft is attached to the spindle 7, which is connected to the electric motor. The control cabinet is attached to the racks with brackets.

The mixing process and the operation of the electric drive are controlled by the controls on the front panel of the cabinet.

The electric motor is equipped with a frequency converter for regulating the rotational speed of the shaft with agitators.

During the preparation of the hydrogel, it is necessary to lift the shaft with a slow-speed stirrer from the reactor and replace it with a shaft with a cutter for the grinding operation. This is provided by a unit that can be moved vertically.

The design of the homogenizer is shown in FIG. 7. The homogenizer consists of the main working parts, including a cylindrical body 24 with a heat exchange jacket 19 and a hollow cylindrical-conical piston 20 located in it coaxially. The piston is equipped with a guiding support 23 made in the form of a ring with partitions, which play the role of a suspension flow distributor going for grinding. The guide support 23 is installed in the groove of the inlet pipe with the possibility of longitudinal movement. The piston is moved by an adjusting screw 21. The surface of the piston, made in the form of a truncated cone 22, is provided with guide grooves, which provide additional grinding when the suspension flow through the gap moves.

When entering the homogenizer, the product (suspension) passes the distributor support, is divided into four equal streams, enters the space between the front cover of the housing 25 by the conical end of the piston, and then the material is evenly distributed over the section of the apparatus and enters the gap between the piston and the cylindrical part of the housing. When the suspension is pushed through the homogenizer, the particles are crushed, which have a flat shape and a size of no more than 300 microns.

Thus, the analysis of the installation for the production of particles of hydrogel material showed that a set of reactor devices with replaceable mixers and knives, operating sequentially at different speeds of rotation, makes it possible to obtain in one apparatus first a suspension, then a tabletted hydrogel and, after exposure to a knife grinder, a suspension with an average particle size of 800 μm ... The use of a dispersant makes it possible, after passing through the gaps between the piston and the housing, to obtain particles with a size of 175 to 300 μm.

The installation works as follows. The components of the mixture for preparing the hydrogel are loaded into the reactor through the inlet pipes. In this case, a frame agitator operates, the rotation frequency of which is 50-500 min ^-1 . Further, at a constant speed of rotation, pigment and other initiators are introduced through the inlet pipe. Stir with a slow-speed stirrer at 50 rpm for 5 minutes until the acrylamide is completely dissolved. A 1% aqueous solution of tetramethylethylenediamine (TMED) is metered into the resulting solution and stirred for another 5 minutes.

Separately, a water-glycerin paste containing a protective marker in the form of 20% inorganic phosphor K-77 is prepared in a bead mill.

The prepared paste with fillers is then dispensed into the reservoir with the solution for preparing the hydrogel, and stirring is continued at a frequency of 100 rpm for 5 minutes.

Then the initiator of polymerization, ammonium persulfate in the amount of 1% solution is dosed into the reservoir. The mixture is brought to the final volume with water and stirring is continued with a frame stirrer until the onset of the primary polymerization of the solution, at which an elastic hydrogel block is formed, but its final elasticity is not achieved. In this case, in order to avoid adhesion of the formed hydrogel block to the walls of the reactor, the frame mixer is not stopped.

Then the frame mixer is replaced with a high-speed cutter with a rotation speed of 1000-1500 rpm and slowly lowered into the working volume, adding the required amount of water in a volume of 230% of the hydrogel weight. In this case, the rate of immersion in the hydrogel briquette is comparable to the rate of polymerization and crosslinking. In the final stage, the cutter disperses the hydrogel briquette into particles with a volume of 0.5-1.5 cm ³ .

Then, using a screw pump, the mass with fragments of the hydrogel is fed first through the annular gap of the homogenizer, where, under pump pressure, it is pushed through a mesh cartridge with two meshes, and then the mixture passes through a mesh cartridge with a mesh size of 350 μm and 500 μm.

The installation is considered on the example of obtaining aqueous suspensions of polyacrylamide gel, but it can also be used to obtain a hydrogel composite material with physical properties similar to polyacrylamide gel.

Below are examples of the preparation of aqueous suspensions of polyacrylamide gel.

Example 1.

The process of obtaining a hydrogel block and its preliminary grinding is carried out in a reactor with a jacket for heating with a volume of 1 m ³ , equipped with a low-speed frame mixer and a high-speed top-drive gear disc cutter with sharply sharpened blades located at an angle of 45 degrees to the horizontal and a screw pump with a frequency converter and a homogenizer with strainer.

38.8 kg of acrylamide and 51.2 l of a 1% aqueous solution of methylene bis-acrylamide are dosed into the reactor. Stir with a slow-speed stirrer at 40 rpm for 5 minutes until the acrylamide is completely dissolved. The resulting solution is metered with 5.12 L of a 1% aqueous solution of tetramethylethylenediamine (TMED) and stirred for another 5 minutes.

Separately, a water-glycerin paste is prepared in a bead mill, containing a protective marker in the form of 8% organic phosphor ORLUM 520 and 20% inorganic phosphor FAM-810 / 1000-1.

12 kg of the prepared paste with luminophores are then dosed into the reservoir with the solution for preparing the hydrogel and mixed with a knife mill at a frequency of 50 rpm for 5 minutes.

The cutter allows for efficient mixing of the suspension, which ensures a uniform distribution of phosphor particles throughout the entire volume of the working solution.

Then the initiator of polymerization, ammonium persulfate in the amount of 44.8 l of 1% solution is metered into the reservoir. The mixture is brought with water to a final volume of 320 l and stirring is continued with a frame stirrer until the onset of the primary polymerization of the solution, at which an elastic hydrogel block is formed, but its final elasticity is not achieved. In this case, in order to avoid adhesion of the formed hydrogel block to the walls of the reactor, the frame mixer is not stopped. The final polymerization is accompanied by the final set of elasticity of the hydrogel, and which occurs already in the crushed agglomerates of the hydrogel. Grinding is carried out by turning on a gear cutter with a shaft rotation frequency (1000-1500) rpm and slowly entering it into the working volume. Grinding is continued, water is gradually added to the required amount in a volume of 150% by weight of the hydrogel. The result is a mixture of fragments of hydrogel material with a particle volume of (1-2) cm ³ . Then, using a screw pump, the mass with fragments of the hydrogel is fed into the homogenizer, where, under pump pressure, it is pushed through the annular gap with a given size, and then through a mesh filter. The resulting suspension is recycled through a pipeline back to the reactor.

The final particle size of the hydrogel material is determined by the mesh size of the strainer, the set annular gap, and the number of times the suspension passes through the homogenizer.

In this example, the slurry was passed through a homogenizer for 5 cycles, the mesh filter included a stainless steel mesh with a mesh size of 500 μm.

As a result, a 30% aqueous suspension of particles of the hydrogel material is obtained with the following particle size distribution: d (0.1) = 100 μm, d (0.5) = 530 μm, d (0.9) = 1050 μm. The total amount of suspension with hydrogel particles was 800 kg.

To check the special properties, paper casts were made on a laboratory sheet-molding machine, with a suspension of hydrogel particles of 1.5% by weight of absolutely dry cellulose fiber. In the resulting paper casts, particles of the hydrogel material under the influence of UV radiation (365 nm) were visualized as dots with green-yellow luminescence; under the influence of infrared radiation (980 nm) - as dots with green luminescence. Particles cannot be removed mechanically from the paper. When the paper is viewed in transmission and in reflected rays, the particles of the hydrogel (polymer mesh) are not detected visually.

Example 2.

The process of obtaining a hydrogel block and its preliminary grinding is carried out in a reactor vessel with a jacket for heating with a volume of 1 m ³ , equipped with a slow-speed frame mixer, a high-speed top-drive disc gear cutter with sharply sharpened blades located at an angle of 45 degrees. to the horizontal and screw, a pump with a frequency converter and a homogenizer with a mesh filter.

24.3 kg of acrylamide and 43.2 l of a 1% aqueous solution of methylene bis-acrylamide are dispensed into the reservoir. Stir with a slow-speed stirrer at 40 rpm for 5 minutes until the acrylamide is completely dissolved. The resulting solution is dosed with 22.8 L of a 1% aqueous solution of tetramethylethylenediamine (TMED) and stirred for another 5 minutes.

Separately, a water-glycerin paste containing a protective marker in the form of 20% inorganic phosphor K-77 is prepared in a bead mill.

6.75 kg of the prepared paste with phosphors is then dosed into the reservoir with the solution for the preparation of the hydrogel and mixed with a knife mill at a frequency of 50 rpm for 5 minutes.

Then the initiator of polymerization, ammonium persulfate in the amount of 37.8 l of 1% solution is dosed into the reservoir. The mixture is brought to a final volume of 270 l with water, and stirring is continued with a frame stirrer until the onset of the primary polymerisation of the solution, at which an elastic hydrogel block is formed, but its final elasticity is not achieved. In this case, in order to avoid adhesion of the formed hydrogel block to the walls of the reactor, the frame mixer is not stopped.

Further grinding is carried out by turning on a toothed disk cutter with a shaft rotation frequency (1000-1500) rpm. Grinding is continued, water is gradually added to the required amount in a volume of 230% by weight of the hydrogel. The result is a mixture of fragments of hydrogel material with a particle volume of (0.5-1.5) cm ³ .

Then, using a screw pump, the mass with fragments of the hydrogel is fed into the homogenizer, where, under pump pressure, it is pushed through the annular gap and a mesh filter with two meshes with a mesh size of 350 μm.

In this example, the slurry is passed through a homogenizer for 12 cycles. As a result, a 30% aqueous suspension of hydrogel material particles was obtained with the following particle size distribution: d (0.1) = 65 μm, d (0.5) = 400 μm, d (0.9) = 740 μm. The total amount of the suspension with hydrogel particles was 900 kg.

To check the special properties, paper casts were made on a laboratory sheet-molding machine, containing a suspension of hydrogel particles of 2% by weight of absolutely dry cellulose fiber. In the resulting paper casts, particles of the hydrogel material under the influence of UV radiation (365 nm) were visualized as dots with red luminescence. Particles cannot be removed mechanically from the paper. When the paper is viewed in transmission and in reflected rays, the particles of the hydrogel (polymer mesh) are not detected visually.

The given examples 1 and 2, as well as 3 and 4 are presented in table 1. From table 1 it can be seen that the most optimal yield of an aqueous suspension is observed in examples 2 and 3. In this case, the particle size fluctuates in the range (20-700) microns with a minimum amount concentration of particles and added (15 and 5%) water.

Claims (2)

1. Installation for the production of particles of composite hydrogel material, containing a reactor with a slow-speed stirring device and a heating jacket, a unit for coarse grinding of briquetted hydrogel, a dispersion unit on a special grid and a unit for dividing the suspension into small fractions, characterized in that it additionally contains a high-speed top-drive unit. grinding in the form of a high-speed toothed disk cutter or a knife cruciform cutter with knives, and outside the reactor there are installed: a device for lowering and raising the cutters, a dispersion unit containing a pump for pumping suspensions, a two-zone disperser made in the form of a cylindrical body with a cylindrical-conical piston with guide grooves made on its conical surface and equipped with a distribution ring with partitions and a mesh filter, and the devices are installed in series and connected by a pipeline system for removing suspensions with large particles amy to the unit for dispersing and returning the crushed hydrogel to the reactor for redispersion. 2. An installation according to claim 1, characterized in that the cross-shaped cutter is made in the form of four cruciform plates with four triangular knives placed on them from the outer and inner surfaces with the possibility of moving them around the circumference relative to the plates by 45-135 degrees.

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