RU2704190C1 - Method of producing organomodified montmorillonite (mmt) - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of modifying inorganic aluminosilicate filler, montmorillonite (clay) MMT using organic water-soluble biodegradable modifiers and can be used in making composites with improved characteristics (high degree of grafting and physical and mechanical properties). It can be used in medicine as biodegradable implants for targeted drug delivery into the body. Method of producing organomodified montmorillonite (MMT) by mixing of MMT previously dispersed in water with water-soluble oxy- or amino acids or their mixtures, lactones or lactams, followed by copolycondensation of component at temperature of 20–100 °C and initial weight ratio of MMT:Modifier:Water=2–30:1.5–50:40–95, with removal of water during copolycondensation. Oxyacids used are lactic or glycolic acid, ε-aminocaproic acid is used as amino acids, lactide, or glycolide, or ε-caprolactone is used as lactones, ε-caprolactam is chosen as lactams.

EFFECT: invention allows reducing the temperature of the grafting process up to room temperature and increasing the degree of grafting of the organic component.

1 cl, 10 dwg

Description

The invention relates to a method for modifying an inorganic aluminosilicate filler, montmorillonite (clay) using various organic water-soluble biodegradable modifiers. The obtained modifiers can be used to create composites with improved characteristics (a high degree of grafting and physical and mechanical properties, respectively), which can be used in medicine as biodegradable implants, for targeted delivery of drugs to the body, etc.

State of the art

There are many ways to modify montmorillonite and to obtain composites for various purposes based on the obtained modifiers. The options closest to the proposed technical solution are presented in this list.

1. RF patent 2513766.

Known superconcentrate based on a cyclic oligomer of butylene terephthalate and urea-modified montmorillonite. Modification and combination is carried out in a solution of methylene chloride.

2. RF patent 2444562.

Composite antifriction lubricant containing nanomontmorillonite modified with 1,1,9-trihydroperfluorononanol (content of 40 wt.%). The modification is carried out using ultrasound at a temperature of 70 ° C.

3. EP 1055706.

Nanocomposite polymer / clay with low oxygen permeability. Obtained by mixing several organic components, including polyethylene, polystyrene, polyparachlorostyrene and various curable thermoplastic resins, and as an inorganic one, clay clay layered.

4. RF patent 2375304.

Clay containing a charge; compensating rosin-based organic ions and nanocomposite materials containing such clay.

5. RF patent 2430883.

A method of obtaining an antifriction composite based on ε-caprolactam, perfluorinated alcohols and montmorillonite, carried out in two stages. At the first, clay is dispersed and modified in an ethanol solution, at 70 ° C, under the action of ultrasound. After isolation of the modifier, it is subjected to co-oligomerization at 170 ° C, accompanied by the formation of covalent bonds between lactam and alcohols, as well as grafting to clay.

6. Pat RF 2443728.

A known method of producing a polymer / clay composite (closest to the claimed) by preliminary extruder combining organo-modified clay with a polymer at a high filler content (51-70%), allowing at the same time to achieve a high degree of exfoliation. The resulting superconcentrate is further diluted with a matrix polymer to the optimum degree of filling (0.1-30%), which guarantees higher physicomechanical characteristics of the composite.

7. RF patent 2516669.

In a later patent it was shown that in order to obtain a composite based on polyethylene and modified montmorillonite resistant to cracking and suitable for protective coating of wires, similar operations can be carried out at filler concentrations of 20-40% (masterbatch) and 0.1-20% in final polymer.

8. RF patent 2482137.

A known method of producing an elastomeric composite containing montmorillonite by mixing aqueous elastomeric latex with an aqueous suspension of montmorillonite, coagulating their mixture with subsequent mechanical action on it and obtaining a plasticized masterbatch.

9. RF patent 2519174.

Clay-modified montmorillonite based on clay of a pre-modified quaternary ammonium salt and resorcinol adiphosphate oligomer.

10. RF patent 2433954. Clay modifier distearylmethylammonium chloride.

11. RF patent 2417161.

Acrylate guanidine in combination with montmorillonite and its radical polymerization initiated by persulfate.

12. RF patent 2412114.

A method of producing intercalated nanocomposites based on layered aluminosilicates and organic materials, allowing further contact of the resulting hybrid materials with food and including polyvinyl alcohol, biopolymers, antimicrobial peptides, antioxidants, drugs, vitamins. The method is carried out in an aqueous or aqueous-alcoholic medium in several stages, including reducing the size of the layered particles, pretreating them with expanding the interlayer space, intercalating organic materials into clay with an expanded interlayer space, to obtain a masterbatch and introducing it further into the plastic matrix.

13. RF patent 2433954.

A method for modifying an aqueous dispersion of smectite clay is proposed, which is carried out by preliminary sodium activation by washing with a sodium chloride solution, separating naturally dispersed coarse impurities, and treating the resulting product with compounds containing an organic cation, followed by isolation and drying of the modifier. Organic cations are selected as organic compounds, which necessarily contain at least one organic radical of various structures with a sufficient number of carbon atoms.

14. RF patent 2520434.

A method of obtaining clay modified in water with a zwitterionic monomer acrylate or methacrylate guanidine. The resulting organomineral product improves the compatibility of the organic and inorganic components of various composites.

15. US patent 9518134.

An aqueous absorbent obtained on the basis of modified clay and containing carboxyl or carboxylate functional groups is proposed. The absorbent is synthesized by grafting acrylic acid, its polymers or oligomers onto clay particles dispersed in water. Vaccination is carried out by a radical initiated polymerization of acrylic acid and is accompanied by the formation of covalent bonds between the filler (clay) and the organic modifier.

Thus, from the proposed list of patents close to the proposed technical solution, it follows that the improvement of the properties of MMT during modification occurs as a result of a series of preliminary operations that contribute to the separation of clay particles (mechanical impact, ultrasound, processing with predecessors, etc.). Modification of MMT with an organic component is carried out mainly in the melt of the modifier, in an aqueous or non-aqueous medium. In this case, a simple mixing of the components or grafting of the organic component to the clay occurs.

The set of essential features proposed by the authors in published sources was not found.

The technical problem solved by this invention is to simplify the method of modifying MMT by eliminating preliminary operations, the possibility of introducing, condensing and grafting a biodegradable organic component based on hydroxy and amino acids, as well as their cyclic derivatives, into a composite in an aqueous medium using high catalytic properties of clay .

The technical result is to reduce the temperature of the process down to room temperature and to obtain a high degree of grafting of the organic component.

To achieve the technical result, a method for producing organically modified montmorillonite (MMT) by mixing MMT previously dispersed in water with modifiers, which are selected as water-soluble hydroxy or amino acids, or mixtures thereof, lactones or lactams, followed by copolycondensation of the component at a temperature of 20-100 ° C and the initial mass ratio of MMT: Modifier: Water = 2-30: 1.5-50: 40-95, with the removal of water during copolycondensation.

In this case, lactic or glycolic acid is chosen as hydroxy acids, ε-aminocaproic acid is selected as amino acids, lactide or glycolide, or ε-caprolactone is selected as lactones, ε-caprolactam is chosen as lactams.

The essence of the proposed method is as follows.

Clay modification with a biodegradable polymer is carried out in aqueous dispersions, where its hydrophilic affinity is manifested to the greatest extent.

As modifiers, bifunctional water-soluble hydroxy or amino acids having terminal unlike functional groups capable of self-condensation and the formation of polymers containing an intrachain chemical bond, which may undergo further biodegradation, are selected.

It is possible to use for the modification and cyclic derivatives of oxy- or amino acids - mono- or dilactones or lactams, which are susceptible to hydrolysis in water and the formation of oligomeric acids with the same combination of terminal functional groups.

The modification is carried out at room temperature (or elevated to 50-60-100 ° C) with slow portioned or one-time introduction of components into each other, clay into acid or acid into clay. The latter option is more preferable, because helps maintain the pH of the medium during the modification process closer to neutral and increase the degree of grafting, as well as a higher degree of exfoliation of the mineral component.

If cyclic compounds are chosen as a modifier, the pH is neutral throughout the process, since their hydrolysis under the action of alkaline clay occurs rather slowly and is synchronized with the subsequent self-condensation of the resulting functional groups.

The selection of the ratio of the components is carried out in a wide weight range in the clay range: modifier: water = 2-30: 1.5-50: 40-95. With an excess of clay in the resulting product, it can be qualified as a “modifier”, with an excess of organic component as a “composite”.

The nature of the mixing of the system during the modification is determined by the choice of clay concentration in water. With a value of 1-2%, it can be periodic and carried out by a conventional mixing device (paddle or magnetic stirrer). In systems with high viscosity (clay concentration up to 20%), agitators with a sufficiently high torque are required, and at concentrations above 20% - plastic deformation, the most advantageous option of which is the rolling of plasticine-like mass. In all mixing devices, designs that create shear stresses that contribute to the disaggregation of clay particles and its activation, respectively, are preferred.

The main advantages of the proposed method for modifying clay are as follows:

1. The formation of a biodegradable polymer and its grafting to a mineral filler is carried out in an aqueous medium, which fundamentally distinguishes the proposed method from widely known, carried out in homogeneous, solution or melt, but equilibrium conditions. In the proposed embodiment, the polymer is deposited on the surface of the filler (clay), grafted to it and is taken out of equilibrium, which makes it possible to obtain the desired product with a rather high polymer yield (25-100%, see examples).

2. The proposed method for modifying clay with a biodegradable polymer does not require a specially introduced catalyst, the function of which is performed by the filler itself, whose alkaline nature is largely responsible for catalysis.

3. The high catalytic properties of clay are manifested in the possibility of condensation of bifunctional acids at room temperature. A similar process in solution or melt (for example, under the action of tin or its salts) requires elevated temperatures (above 100 ° C).

4. Clay, in addition to its basic aluminosilicate composition, which is not toxic to a living organism, contains a number of microelements that contribute to repair processes during the restoration of living damaged tissues (in particular bone). The healing properties of clay are well known in the literature.

List of figures attached to the description

FIG. 1 TGA of a sample of montmorillonite (Na +), modified by treating it with an aqueous solution of lactic acid by the method of slowly introducing clay into acid (example 1 of the description).

FIG. 2 TGA montmorillonite (Na +), modified with L-lactic acid by the method of slow (batch) introduction of acid into an aqueous dispersion of clay (example 2 description).

FIG. 3. TGA sample of montmorillonite (Na +), modified with an aqueous solution of lactic acid by a single-stage rolling process with a high initial clay content (stage 1, description example 3.1).

FIG. 4. TGA sample of montmorillonite ((Na +), modified with an aqueous solution of lactic acid by the method of re-rolling in the presence of an additional amount of modifier (stage 2, description example 3.2).

FIG. 5. TGA sample of montmorillonite (Na ⁺ ), modified with glycolic acid (example 4 description).

Fig 6. TGA sample of montmorillonite (Na ⁺ ), modified with L-lactide in water (example 5 oa ⁺ ), modified with ε-caprolactone in water (example 6 of the description).

FIG. 7 TGA of a sample of montmorillonite (Na ⁺ ) modified with ε-caprolactone in water (example 6 of the description).

FIG. 8 TGA of a sample of montmorillonite (Na ⁺ ) modified with ε-aminocaproic acid in water (example 7 of the description).

FIG. 9 TGA of a sample of montmorillonite (Na ⁺ ) modified with ε-caprolactam in water (example 8 of the description).

FIG. 10 Montmorillonite (Na ⁺ ), modified with a mixture of lactic and glycolic acids (example 9 of the description).

Example 1

The example illustrates the possibility of condensation of lactic acid by the action of an aqueous suspension of montmorillonite and grafting the resulting polylactic acid to clay particles.

The following components are loaded into a 100 ml glass beaker equipped with a magnetic stirrer: L-lactic acid (MK, concentration 90%), which is diluted with water and montmorillonite Na ⁺ (MMT), which is introduced gradually with stirring, in small portions, over 3 hours. The weight (percent) composition of the resulting mixture of MMT: MK: water = 22.3: 31.1: 46.6. The ratio of the components excluding the added MMT water is 49.9%, MK - 50.1%, the molar acid content exceeds the molar sodium content in clay by 15.4 times. The mixture is stirred for another 2 hours, turning into a creamy non-settling suspension, its acidity changes gradually from pH = 4 to pH = 5. The resulting suspension is left to stand for 24 hours and the precipitate is dried without heating to constant weight.

There is no water extract from the precipitate, and methylene chloride slowly erodes it with the appearance of a solution viscosity, which qualitatively indicates the presence of a lactic acid polymer. The clay content in the resulting modifier, adjusted for the loss of water released as a result of acid condensation, was 49.9%.

According to the TGA (Fig. 1), the clay content estimated by the weight loss of the sample when heated to 450 ° C is close to 50%. This means that almost all of the introduced acid is fixed on the carrier (clay) in the form of a polymer (100% conversion), the bulk of which breaks up in the temperature range 175-400 ° C.

Example 2

The example illustrates the possibility of condensation of lactic acid by the action of an aqueous suspension of montmorillonite and grafting the resulting polylactic acid to clay particles. The difference from example 1 lies in the method of input of the components. In this example, the acid is slowly introduced into the clay suspension. This allows you to longer lead the vaccination process in the range of acidity closer to neutral.

2.97 g of montmorillonite (Na ⁺ ) is introduced into a glass beaker equipped with a magnetic stirrer and 100 ml of distilled water are added. The concentration of clay was 2.88%. Using a magnetic stirrer, the clay is dispersed in water to a state in which there is no precipitating fraction. L-lactic acid (90% concentration) was added dropwise to the resulting suspension, with stirring, for 2 hours. The molar excess of the introduced acid exceeds the molar content of sodium in clay by 6 times, while the pH of the system remains neutral. This unequivocally shows that excess acidity disappears not only as a result of neutralization of sodium clay, but also in parallel to the polycondensation of MK.

The gradual addition of acid with stirring is continued for another 3 hours until a weak acidity appears (pH drops from 6 to 4) and a molar excess of carboxylic acid groups with respect to alkaline clay groups equal to 14.3. Get a slime-like, non-settling mass of the composition MMT: MK: water = 3.9: 5.0: 91.1, which is dried further at room temperature to constant weight and converted into a powder with a particle size of 0.1-0.3 mm

The obtained powder, in contrast to the sample obtained according to example 1, is well dispersed with water and more difficult with methylene chloride, thereby showing the presence of grafted polymer and a certain diphilicity of its properties.

The TGA of the obtained modifier (composite) is shown in FIG. 2, from which it follows that the grafted organomineral copolymer is present and its thermal decomposition in comparison with the sample of example 1. proceeds more intensively due to the more developed surface of the modifier.

Thus, it clearly follows from Examples 1 and 2 that in the presence of montmorillonite, the polycondensation of lactic acid can be carried out in an aqueous medium. At the same time, the resulting polymer covalently binds to the aluminosilicate base, is deposited on the surface of the carrier, is taken out of equilibrium, and the equilibrium nature of homogeneous condensation essentially turns into nonequilibrium, allowing the reaction to proceed with a sufficiently high yield of the final product. The high catalytic properties of clay are also demonstrated. a homogeneous reaction, a characteristic feature of which is a fairly high temperature (above 100 ° C), becomes in this (heterogeneous) version feasible at room temperature.

Example 3

An example illustrates the modification of montmorillonite with L-lactic acid in an aqueous medium at a high initial clay concentration.

1. 28.9 g of montmorillonite (Na ⁺ ) is introduced into a 250 ml glass beaker and 185 ml of distilled water are added. Clay is dispersed using a mechanical stirrer into a suspension that partially settles during aging. The concentration of clay in suspension is 13.5%. 6.2 g of L-lactic acid (90% concentration) was added to the resulting suspension, and the mixture was triturated with a mechanical stirrer at room temperature for 5 hours. Get an aqueous plasticine-like clay concentrate of the following percentage composition MMT: MK: water = 13.2: 2.5: 84.3. The weight content of MMT in relation to MK was 84.1%. The molar ratio MK / MMT = 2.14. Despite a 2-fold excess of the acid groups of MK in relation to alkaline clay groups, the pH of the system is 6.5.

The mass is divided in half and half is kneaded into a plate, which is dried to constant weight. The dried sample is ground and subjected to extraction with water or methylene chloride (XM). Water extraction is absent, and in XM the sample is washed out into a viscous dispersion, which qualitatively fixes the presence of polymer.

The TGA of the obtained sample is shown in FIG. 3, from which it follows that the content of the mineral component in the sample is not less than 89% (in the temperature range up to 450 ° C), which is in good agreement with the content corrected for water loss by the modifier as a result of condensation (87.8%).

2. The second half of the sample is subjected to the following manipulations. A plasticine-like mass is kneaded into a sheet 2-3 mm thick, which is moistened with lactic acid, folded several times and the resulting stack is rolled again into a sheet 2-3 mm thick. The operation (rolling) is repeated several times, adding a new portion of MK, while lactic acid is quickly absorbed by the modifier (composite), binds and increases the elasticity of the deformed mass. The amount of bound (additional) acid was approximately 50% (not taking into account both the water contained in it and the resulting condensation). The molar ratio MK / MMT increased to 3.6. An aqueous sample of the obtained sample still remained neutral, indicating that almost all additionally introduced acid was bound in the form of a polymer (100% conversion).

The TGA of the sample subjected to further modification is shown in FIG. 4, from which it follows that the clay content decreased to 60%, and the grafted polylactic phase increased to 40% (at a limiting temperature of 450 ° C).

The given example proves the possibility of modifying montmorillonite at its high concentration, both in the initially prepared water-containing mixture and in the concentrated modifier (composite). A prerequisite for this is the presence of sufficiently intense shear forces that cause exfoliation of clay particles, the exfoliated state of which is fixed by grafting a modifier (lactic acid polymer).

Example 4

The example illustrates the possibility of modifying montmorillonite (Na ⁺ ) with glycolic acid (HA).

8.51 g of montmorillonite (Na ⁺ ) and 56.4 g of distilled water (clay concentration 13.1%) are introduced into a 150 ml glass beaker equipped with a magnetic stirrer. With stirring, a partially settling suspension is obtained. Then, glycolic acid is introduced in small portions for 3 hours until the molar ratio HA / MMT = 2.93 and pH = 5. Complete neutralization of clay occurs at a molar ratio HA / MMT = 1.8. The resulting percentage composition of the mixture, including water, MMT: HA: water = 12.5: 4.3: 83.2. The ratio of clay 74.4% and modifier (GK) 25.6%.

In order to remove sodium ion from the system, the mixture is further treated with monochloroacetic acid (MCC) in an amount of 1.0 g (10.6 mmol) for 4 hours. The resulting well-precipitated suspension is filtered, washed twice with water to remove sodium chloride and dried to constant weight. The filtrate is combined and also dried to determine the yield and balance of material. 8.56 g of washed modifier (composite) are obtained, the yield of which from the sum of the initially introduced HA and MMT is 82%, which exceeds the content of the originally introduced clay 74.4% and indicates the presence of HA vaccine on MMT.

The yield of the modifier washed with water, counting from the sum of the added HA and clay (excluding the water that should be released as a result of condensation of the HA), amounted to 85.4%, which exceeds the content of the initially introduced clay (74.4%). In addition to sodium chloride, nano-clay and glycolic acid oligomer are detected in the dried filtrate, which have passed through the filter, which explains the grafting deficiency determined by the method of extractive separation of the components.

The presence of grafted polyglycolide in the washed modifier is also proved by TG analysis. The corresponding curve is shown in FIG. 5, which shows that there is an organic component in the modifier, the content of which is close to 15% (when heated to 450 ° C). As in the variant of extractive separation, the deficiency of the organic phase is confirmed, however, the fact of its inoculation onto the inorganic phase remains unshakable.

Example 5

An example illustrates the possibility of modifying (Na ⁺ ) montmorillonite with L-lactide in water.

Into a 200 ml glass beaker equipped with a magnetic stirrer, 14.4 g of montmorillonite and 1.88 g of crystalline L-lactide are introduced. The contents are poured into 105 ml of distilled water, the magnetic stirrer is launched and stirred at room temperature for 5 hours. The mass composition of the mixture of MMT: lactide: water = 11.9: 1.6: 86.5. The clay and lactide contents are 88.2% and 11.8%, respectively. The molar ratio of lactide / clay = 0.909 (mol / mol). During mixing, control the pH of the system, which is neutral along and at the end of the reaction. Lactide is completely dissolved with stirring. A creamy, non-settling mass is obtained which is dried further in air to a constant weight.

Using the TGA method, the established clay content in the modifier was about 86% (upon reaching a temperature of 450 ° C), i.e. slightly less than it was at the beginning (see Fig. 6). The indicated discrepancy is due to the formation of a rather perceptible amount of nano-clay, which evaporates along with the decomposing polylactide modifier during heating.

The most likely vaccination mechanism in this embodiment is the preliminary hydrolysis of the lactide, accompanied by the opening of the cycle, the preparation of a dimeric ester hydroxy acid, soluble in water, which further condenses with silanol or hydroxyaluminate groups of aluminosilicate. The alkaline groups of the aluminosilicate itself are catalyzed by the indicated hydrolysis.

Example 6

The example illustrates the possibility of modifying montmorillonite (Na ⁺ ) with ε-caprolactone (ε-CL) in water.

13.6 g of montmorillonite, 7.275 g of ε-caprolactone and 84 g of distilled water are introduced into a 150 ml glass beaker equipped with a magnetic stirrer. A mixture of the composition MMT: ε-CL: water = 12.9: 6.9: 80.2 is obtained. . The molar ratio of lactone / clay = 4.69 (mol / mol). The weight ratio of clay is 65.2%, ε-caprolactone 34.8%. The mixture is dispersed at room temperature for 3 hours and then still incubated for 2 days. A sour cream-like, non-settling mass is obtained, which is dried in air to constant weight and analyzed by the TGA method for vaccination (see Fig. 7). It can be seen from the figure that the sample contains a grafted polymer, the main decay of which occurs near 350 ° C. It is characterized by an overestimated clay content of 78% (450 ° C) and, accordingly, an underestimated content of grafted organic phase in comparison with the initially dosed monomer (22% versus 34.8%, polymer yield 63.2%).

In this regard, it should be noted that the indicated discrepancy between the dosage and TGA may be due to at least two reasons. One of them is formulated in Example 5, according to which an underestimation of clay content by TGA may be due to its volatility during determination due to the formation of a nano-fraction. The second reason for the discrepancy is associated with the high catalytic activity of clay, which cokes the organic phase, which delays its decomposition, respectively, volatility and leads to an overestimation of the content of the inorganic component. Both reasons can balance each other out.

Example 7

The example illustrates the possibility of modifying montmorillonite (Na ⁺ ) with ε-aminocaproic acid (ε-ACC) in its aqueous solution by slow introduction of clay.

40 g of distilled water are introduced into a glass beaker equipped with a magnetic stirrer, in which 0.685 g of ε-ACA are dissolved, then 0.992 g of clay is introduced in small portions not exceeding 30-50 mg with stirring for 3 hours. The amount of acid is further increased to a total content of 1.707 g and the mixture is incubated for a day. A stable, creamy suspension (pH = 7) is obtained which does not settle upon standing, the percentage of which is MMT: ACC: water = 2.4: 4.2: 93.4. The molar ratio of ACC / MMT = 13.3. Clay content is 36.4%, ACC is 63.6%, respectively. TG analysis of the obtained sample is shown in FIG. 8, from which it can be seen that the obtained curve differs in at least two characteristic regions, the first in the range of 200-280 ° C, the second 300-450 ° C. The final clay content was 30%. The low-temperature site can be attributed to the evaporation of the ACC, which has not reacted (T _{boiling point} = 255 ° C at 760 mm Hg), and the high-temperature site, due to the decomposition and removal of the resulting grafted polymer. The discrepancy between the initially introduced amount of clay (36.4%) and obtained in accordance with the TG analysis (30%) may be due to the imbalance of the components in the analysis process, however, the fact of vaccination remains undeniable.

Example 8

The example illustrates the possibility of modifying montmorillonite (Na ⁺ ) with ε-caprolactam (ε-CL) in an aqueous medium.

In a glass glass with a capacity of 200 ml, a mixture of the following composition is prepared: montmorillonite - 12.0%, ε-CL - 17.2%, water - 70.8%. The molar excess of ε-CL in relation to clay functional groups is 12.6. The clay content (excluding water) is 41.1%, ε-CL - 58.9%, respectively. The mixture is kept at room temperature with periodic stirring for 7 days, during which partial settlement of clay is observed (20-30% of the height). The resulting suspension is filtered, washed several times with distilled water from the remains of unreacted lactam and dried at room temperature to constant weight. The filtrate and wash water are summarized and also dried. The extractive separation of the modifier showed that the yield of the insoluble part exceeded the initial clay dosage by at least 26.7%, which can be qualified as the content of the grafted fraction. TG analysis is shown in FIG. 9, from which it follows that the content of the grafted part is determined to be 25%, and the residual clay, respectively, to 75% (at a limiting temperature of 450 ° C). The convergence of the obtained results is satisfactory and unequivocally indicates the possibility of vaccination of lactam on MMT under the accepted conditions.

Example 9

The example illustrates the possibility of modifying montmorillonite with a mixture of L-lactic (MK) and glycolic (HA) acids to obtain their copolycondensate as an organic component of the modifier.

Preliminarily, with slight heating, a solution of glycolic acid in a 90% aqueous solution of lactic acid is prepared. The content of the components L-MK 73.8%, GK -26.2%). 20.8 g of the resulting solution are poured in small portions into 24.0 g of dry clay. After each injection of acids, the mixture is stirred until a dry, free-flowing, uniform powder is obtained, the weight of which is controlled during the process. Weight loss is detected at room temperature during mixing, which clearly indicates the presence of acid condensation at room temperature, catalyzed by clay, and the evaporation of the water formed in this process. The conversion of the acid mixture in 2 hours was 80%. To complete the process, the mixture is continued to mix while heating to 60-70 ° C for another 2 hours. A dry, dusty, powdery modifier is obtained, which is tested for extractability with water and methylene chloride.

It is stated that the obtained modifier containing 61.5% clay at a dosage (taking into account the water lost by MK + HA during condensation) is well dispersed in water with the formation of a viscous dispersion, which settles upon standing for several days, releasing a clear homogeneous solution containing partially dissolved modifier. When the resulting solution is separated from the precipitate and a new portion of water is added to it, a new solution is obtained that is identical to the initial concentration of the dissolved modifier. In both samples, after drying, the presence of clay is confirmed.

The TGA modifier is shown in FIG. 10, from which it follows that the thermal decomposition of the sample is characterized by at least two sections, one in the range of 100-200 ° C, the second 200-400 ° C, while the content of the indecomposable component on the edge of the second range (60%) is close to the initial clay content (61.5%).

Thus, a simple method for modifying MMT by eliminating the preliminary clay processing operations, which is carried out in an aqueous medium at low temperatures (up to room temperature), is easily carried out at high filler contents, giving it hydrophilicity, which makes it attractive for widespread use medicine.

Claims (2)

1. The method of obtaining organomodified montmorillonite (MMT) by mixing MMT previously dispersed in water with modifiers, which are selected as water-soluble hydroxy or amino acids or their mixtures, lactones or lactams, followed by copolycondensation of the component at a temperature of 20-100 ° C and initial mass the ratio of MMT: Modifier: Water = 2-30: 1.5-50: 40-95, with the removal of water during copolycondensation. 2. The method according to claim 1, in which lactic or glycolic acid is selected as the hydroxy acid, ε-aminocaproic acid is selected as the amino acids, lactide, or glycolide, or ε-caprolactone is selected as lactones, and ε-caprolactam is chosen as lactams.

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