SU523627A3 - The method of producing microcapsules - Google Patents

Description

(54) METHOD FOR OBTAINING MICROCAPSULES

This invention relates to the field of encapsulation, in particular, to the acquisition of capsules consisting of a polymer shell containing a material such as a liquid.

There is a method of encapsulation, in which the shell is obtained by polycondensation or polymerization of the shell material.

The reaction to obtain a cured capsule shell is obtained from an amine having a difunctional character, and with a derivative of 1 Acid, which for the production of a polyamide is a difunctional or iol functionalized acid chloride. Capsules prepared in a known manner are subjected to high stresses and strains.

An improved fast and efficient encapsulation process is proposed, which eliminates the need for separation of the encapsulated material. An extremely thin shell or cellular wall of the capsule can be obtained. Inter-surface polymerization is usually carried out by reacting two immiscible liquids, such as water and an organic solvent, respectively, containing the direct interacting, complementary organic intermediate compounds that can interact with each other to form a solid polycondensate.

Such polycondensates, for example polyester, polyurethane, polyurea or other substances, can be obtained from intermediate resins or monomers.

It has been found that efficient encapsulation by surface polymerization of an organic intermediate isocyanate can be accomplished using a process that involves the use of two

mostly insoluble liquids, one of which is called the aqueous phase, the other organic, by which a physical dispersion of the organic phase in the aqueous phase is obtained, the organic phase containing an intermediate organic compound of an isocyanate for a polyurea capsule shell. Interfacial polymerization to form a capsule wall in accordance with the invention involves the hydrolysis of an isodiant monomer to form an amine, which in turn reacts with another isocyanate monomer to form a polyurea shell. During the hydrolysis of the isocyanate monomer, carbon dioxide is released. When the dispersion forms droplets of the organic phase in the continuous liquid phase, for example in the aqueous phase, no other reagent is required. After that, mainly when

moderate dispersion displacement, image 34

The wa-nyu of the polyurea capsule shell substances are substances of the polkatchkrut class of dispersed organic kapellenkoe glycol ethers of linear alcohols. 1 is carried out by heating, the surfactant is removed from the liquid phase or by introducing it is rolled into the aqueous phase, it can also be given a nometic amount of the basic amine or 5 to the organic phase. Without special

other agents capable of increasing stee-links to the phase in which the isocyanate is hydrolyzed over the top, such as an acetoacid, will occur

tat tri-c-butyltin, possibly by additionally dividing and distributing the surface-active pH setting of the dispersion, the substance between each phase and, in a similar way, carried out the desired phase cross-linking reaction depending on their solvent condensation on the surface between the organic . The surfactant is capable of dropping and continuous phase. But not used, provided that a sufficiently high shear rate is obtained in the same way.

satisfactory, separate capsules, having to form a dispersion, a sheath consisting of a polyurea is also found to be the most acceptable

and containing an encapsulated material. What is the center and days of the gambling-active ing-re? According to the invention, the reaction that occurs in this system is the amount

the aid of which forms a capsule shell — irimerously from 0.01 to 3.0 weight. % based on

ly, usually goes to the end, so that in the basics-the aqueous phase. Can be used over the last no unreacted poly-20 concentrations of surfactants

isocyanate. It is not necessary to separate kai-substances without increasing the ability to dissolve for use, i.e., it is enclosed in permissibility.

Capsules material can be used non-in the aqueous or continuous phase in the presence of a protective colloid, which is also present, depending on the type. However, such separation before use can be selected from a wide range of such calls can be carried out with the help of materials. Examples of protec- tion of any conventional separation method used are polyacrylates, including, for example, settling, filter cellulose, polyvinyl alcohol, polyactration or removal of the top layer of collected-polyamide and polymethylvinyl ether, small capsules, washing and, if desired, zone anhydride. The amount of drying used. The product is suitable for use as a colloid. It will depend on various facto-sellase households as pesticides, such as molecular weight, type and effect, additional medium efficiency, compatibility and other agents, such as thickeners, biocides, can be added. it has been found that protective colloid surfactants and dispersants can be added to the aqueous phase prior to adding agents in order to increase the organic to the aqueous phase. On the other hand, during storage and to facilitate application, protective colloid can be added to it. The initial dispersion of the organic phase system after the organic phase or after in the aqueous phase can be maintained according to its dispersion. On the other hand, protective emulsifying or dispersing colloid should be added partly to the organisation agents, while the control of the size phase and partly after the stage should be made by the disk and the shape of the elementary capsules. Usually, from 0.1 to quickly is used with any conveniently-5.0 weight. % based on the aqueous phase, the method of dispersing one liquid in the second organic phase contains another. 45 trial, which has to be encapsulated, and in all cases effective or isocyanate. The encapsulated material first includes the preparation by simply being in concentrated form or

stirring a solution of water, a suitable solution of a water-insoluble solvent,

surfactant, and protective it can be used as a solvent

colloid. These three ingredients include water-50dl polyisocyanate. However, to achieve

or continuous phase of the process. The water-required concentration of active material in

on or continuous phase mainly water-insoluble organic-free product from any Components which solvent can be used

could interact with the material. to dissolve the material and its polyisocyanates or with this type of material. Po-55ta. The encapsulated material to the polyisocyanate

surfactant and protective add simultaneously to the aqueous phase. Cogcolloid in the aqueous phase does not participate in the reaction; they can be added separately during the α-polycononaçacin medication, at which it is formed by stirring in the reactor for

Capsule wall. A time sufficient to form Homo K as an acceptable surface-active and highly radiogenic organic solution, preferences include such well-known bonding methods, such that

nor, as isopropyl naphthalenesulfonate, the nat components of the organic phase are added

ri, polyoxynoxyethylene sorbitol laurate, simultaneously in a pre-mixed

ethoxylated nonylphenols, however, preconditions, i.e., their pre-mixing with suitable surfactants, result in obtaining a homogeneous phase before addition and displacement with the aqueous phase. The amount of organic phase can vary from about i to about 75 vol. % The concentrations of the lower limits are comparatively undesirable, since they produce very dilute capsule suspensions. The preferred amount of organic phase is from about 25 to about 50 vol. % The drive of the organic polyisocyanate determines the properties of the resulting capsule. Poly isocyanates also determine the structural and physical strength of the capsule shell. Organic polyisocyanates used in this process include members of the class of aromatic polyisocyanates, which in turn includes aromatic diisocyanates, the class of aliphatic diisocyanates, high-molecular linear aliphatic diisocyanates and isocyanate prepolymers. Representatives of aromatic diisocyanates and other polyisocyanates include the following: 1-chloro-2,4-phenylene diisocyanate, .l4-phenylene di-diisocyanate, nat, α-phenylene diisocyanate, 4,4-methylene bis (phenyl isocyanate), 2,4-tolylene diisocyanate, tolylene diisocyanate (60%, 2,4-isomer, 40% 2,6-isomer); 2,6-tolylene diisocyanate, 3,3-dimethyl-4,4-biphenylene diisocyanate, 4,4-methylenebis- (2-methylphenyl isocyanate), 3,3-dimethoxy-4,4-biphenylene diisocyanate, 2.2-, 5.5 - tetramethyl-4,4-bnphenylene diisocyanate, 80% 2,4- and 20% of 2,6-isomer of tolylene diisocyanate poly-ethylene polype or isocyanate (RARL). It is highly desirable to use a combination of organic polyisocyanates, such 40 as polymethylene polyphenyl isocyanate and tolylene diisocyanate containing 2.4 and 20% of 2,6 isomers, which gives excellent shells for capsules with exceptional controlled opening properties. The amount of organic polyisocyanate used in the process will determine the composition of the walls of the capsules formed in the process. Usually, based on the organic phase, the organic polyisocyanate will be present at -50 in an amount of more than 2 wt. % This is not a limitation and a larger amount can be used that approaches 100% (but at 100% a product without an encapsulated material is obtained), 55 The preferred range is 2.0 to 75% weight. % organic polyisocyanate, in which an encapsulated product is formed that has an appropriate wall content, i.e. 2.0 - 75%, in particular, a pre-60 respectful range includes 5.0-50.0% of the wall content. ... In accordance with the preferred warpact of the invention, the process uses two mostly insoluble phases as described 65 25 30 35 45 above. The method involves obtaining a physical dispersion of the organic phase in an aqueous or continuous phase, and in this dispersion droplets of the desired size are formed in the aqueous phase. Then, by setting the pH of the resulting mixture: -m — the temperature in an acceptable range, a condensation reaction is carried out on the surface between the drops and the continuous phase. Certain changes in the sequence of the steps of adjusting the pH and supplying the desired heat will be apparent from the following description and examples. The temperature of the two-phase mixture, i.e. the dispersion of the organic phase in the aqueous phase, increases from 40 to 60 ° C. The temperature interg for the condensation reaction, in accordance with this invention, is from 20 to 90 ° C. While the heat for the start of the reaction can be supplied to the dispersion of the ORGYANIC FAST at the time of or after the determination of the value, water (the solution can be heated to the required temperature before adding the organic phase and lispersic. By this method, the pH is adjusted after How dyspepsia is formed and the pH is kept within the limits specified below. According to the invention, it was found that a catalyst capable of revealing the rate of gichrolysis isotthian, for example of the type of basic mine, can be added to ORGYAN COMBINATION OR WAVE GRANDING BEFORE STARTING A CONDENSION RELEASE: For successful implementation of the image, this stage is not necessary.When the catalyst is replaced by an increase in temperature in the process, the resulting PRODUCT can be compared with a non-catalytic system.The temperature increase and the catalyst can be used simultaneously in accordance with this method, so on; so that it is preferable to add it to the organic matter and the system during the displacement of the aqueous organic phase 3. It is believed that various catalysts MAY be suitable and their choice will depend on the factors determined by experts over the years. Certain basic organic, preferably tpbt-amines and alkltin apetates, such as tributyltin acetate and di-c-butyltin dianetat, are used as catalysts. When alkyltin acetate is used, it is taken in amounts from. 0.001 to 1.0 weight. % based on the organic phase. The main organic tertiary amines also include triethylene diamine, .M, -Y, S, N-tet.ramethyl - 1.3 -. butanediamine, trletidamin, 3-N-butilamini others. The number of catalysts will vary depending on the system and conditions. When used. the main organic amine, it will be taken in an amount of from 0.01 to 10 weight. % counting on. the organic phase, .. Often, it is,. This will dissolve easily in a water-insoluble material that needs to be injected. The amount of water soluble in the encapsulated material depends on the nature of the material (usually it is small). However, when a water-insoluble material is used, it is preferred 5 to use small deviations from conventional processes. In such a system, particles with poorly expressed wall structure are formed. Good quality microcapsules can be obtained by adding the appropriate catalyst to the aqueous phase after the formation of the emulsion. In this case, bulk polymerization occurs on the surface where the catalyst is present. Heating the mixture is undesirable, otherwise the polymer will form not only on the surface, but a large amount will be formed in the water-insoluble material, which will serve as the reason for dissolving a large amount of water. This process is preferably carried out at a temperature of 15-30 ° C. The method of adding a catalyst to the aqueous phase after dispersing is not limited to encapsulating only a water-insoluble material that can dissolve a significant amount of water, but also applies to any water-insoluble m material l.m. During the stirring of the aqueous phase, the optic is added. preferably 30 ppels of a highly mixed state. After a long ONE lispg pgipAtlt g TPUGOI. It is possible to igpol any abrasion to create a high shear force, so that it can be guided to or in a 35.05 to 4000 micron. The octural range of buggers is: see from KOHe4iHnr.o. TR-K. Tg -: Lpatnomnom p p pom for petiyynogo ppkmenenii is 1.0 - 100 microns. Described gpogor: apply names for patients with poluli. but odnolor yh n zmepov. After receiving the payment of goods and services, the dyspeptic drugs peep through the action. For balances, neither potetssa tpeblets, but only weakly mixed PCGs. We received a program of encapsulated tempered bargainers, opposed to vRTIchs, and we used the program to compute the pH of the system to get the pH values of the pp. Some kind of greenhouse value depends on the NATURE of the components of the fwc. Themes are similar to surface-active substances, cells. catalysts, temperatures, the material of which must be encapsulated, and others. For example, if a PN of about 7.0 is dropped, then during the reaction, a carbon dioxide will be released. If carbon dioxide emissions are undesirable, the pH should be set to about 7.0. The pH is adjusted after dispersion and retained during the ondensapion reaction. In the aqueous phase, the pH of the yctanavailable before the Hreivoft phase is added and dispersed in it with the help of soluble 86.1045 soluble bases and acids, which do not interact with the intermediate polyisocyanate. Preferably, concentrated sodium hydroxide (25% solution), potassium hydroxide, hydrochloric acid and others are used. The release of carbon dioxide can cause significant unwanted foam formation and / or volume expansion, which prevents the reaction from proceeding. In addition to establishing p. H, a defoamer is used to exclude a significant amount of foam produced by the release of carbon dioxide. With the aid of a defoaming agent, it is possible to obtain satisfactorily encapsulated material in an acidic medium without adding caustic soda to the acidic system. The defoamer can be added at any time during the process where the polymer capsule shells are formed to encapsulate the water-insoluble material. At that time, the condensation reaction on the surface between the drops and the continuous phase proceeds very quickly (mainly the first half hour of the reaction time), the reaction conditions are maintained for 2 to 3 hours in order to guarantee the completion of the condensation reaction throughout the system. With properly Stated conditions or with the right catalyst, the reaction time can be shortened. By the end of the reaction, the formation of the capsule wall is completed, the organic material is encapsulated inside the polycondensate shell, and the encapsulated product crawls, ready for use. Determining areas of application does not require further separation or processing of the encapsulated material, i.e., a ready-to-use product is obtained. . -. . The encapsulated material can be used for various immediate or auxiliary purposes by incorporating the material into other products. The thickness or chemical composition of the capsule wall can be selected or adjusted in various ways. For example, these properties can be conveyed by adjusting the reaction conditions by selecting reagents, especially when creating cross-links, which are determined by the functionality of the polyisocyanate in accordance with the invention. The thickness of the capsule shell can be changed by changing the amount of reagents in the organic phase. One convenient mode for adjusting the size of a capsule is the application of a stirring speed, i.e., i.e., the initial phase transfer of the organic phase, at a higher stirring speed, which leads to an increase in ly shear, smaller capsules can be obtained. and continuously. In a discontinuous process, all the various liquids and reagents are combined into one. The continuous process can be varied with suitable reactors, which can be used for continuous encapsulation. In a continuous process, the dispersing and mixing of the interacting phases is carried out at a certain rate to form a dispersion of droplets in the continuous phase, so that a continuous portion of the dispersion of droplets is added to the reactor, in which the pH can be set and the required amount of heat is supplied to carry out the reaction condensation. In a continuous system, the required reaction rate can be obtained by choosing suitable conditions. Both discontinuous and continuous processes are equivalent and the choice between them depends on the condition of production. Example 1. Water (500 ml) containing 1.0% neutralized polymethylvinyl ether (maleic anhydride) of a protective colloid and 0.2% of a linear alcohol ethoxylate emulsifier (15 3 20) is placed in an open reaction vessel. 160 g of 0-ethyl-5-phenylethylphosphon dithioate (insecticide), 39 g of polymethylene polyphenyl isocyanate and 19.5 g of tolylene diisocyanate are mixed in a separate container. The mixture is added to the reaction vessel and emulsified using a high shear mixer. The range of particles produced is about 1–20 microns. To balance the reaction, only mild agitation is required. The temperature of the reagents is raised to 5 ° C for 17 minutes and, at the same time, the pH of the dispersion is maintained at a value of 8.5 by the addition of a 25% solution of sodium hydroxide. The temperature of the reaction mixture is maintained at 50 ° C. and a pH of 8.5 for 2-1 / 2 hours in order to complete the inter-surface polymerization. At this point, 0.25% sodium bentonite thickener and 0.05% sodium pentachlorophenate biocide can be added to form the product, mine separation or washing. The pH of the product is usually set to 9.75 by adding 25% NaOH solution and the reaction mixture is cooled to room temperature. Example 2. Water (500. Ml) containing 1. 5% protective hydroxypropyl methylcellulose colloid and 0.2% ethoxylated linear alcohol emulsifier is placed in an open reaction vessel. In a separate container, 150-g S-ethyldiisobutylthiocarbamate (herbicide), 35 g of polymethylene polyphenyl isocyanate, 17.5 g of tolylene diisocyanate and 0.05 g of tributyl tin acetate catalyst are mixed together. This mixture is then added to the reaction vessel and emulsified with a high speed mixer. The size of the obtained particles lies in the range from 1 to 20 microns. To balance the reaction, only mild agitation is required. The pH of the reaction medium is adjusted to 8.0 with a 10% sodium hydroxide solution. This value, the pH, is maintained for 3 teas by the continuous addition of 10% sodium hydroxide solution. The presence of a catalyst allows interfacial polymerization at room temperature (25 ° C). Example 3. Water (500 ml) containing 0.5% protective colloid polyacrylamide and 0.2% linear alcohol ethoxylate is placed in an open reaction vessel. In a separate container, 167 g of O-ethyl-S-phenylethylphosphonodithioate (insecticide), 14.5 g of polymethylene polyphenyl isocyanate and 14.5 g of tolylene diisociaate are mixed together. The open phase in the open re-heat is heated to 45 ° C, a solution of which the organic mixture is added to the reactor and is emulsified interfered with by a high shear rate. At this momentum, the pH of the medium is about 6.5. The .vrep times of the particles obtained are from 1 to 20 microns. In order to maintain the equilibrium of the reaction, only weak mixing is required. The pH of the medium is adjusted with a 25% sodium hydroxide solution to 8.5. The temperature of the reaction mixture is 50 ° C. The temperature and ipH of the reactive mixture are maintained at 50 ° C and 8.5, respectively, for 3 hours to complete the interfacial polymerization. The pH is maintained at 8.5 by the continuous addition of 25% sodium hydroxide solution. At this point, a sodium bentonite thickener can be added to the capsule dispersion and a pH of 9.8 can be set to form an encapsulated material without further separation or processing. The product is cooled to room temperature. This product can be quickly dispersed in water and discrete capsules can be observed under a microscope. Example 4. Water (100 ml) containing 3% polyacrylate protective colloid, 0.2% linear alcohol ethoxylate emulsifier, is placed in an open reaction vessel. In a separate container, 30 g of 4-ethylphenylgaranyl ether-6,7-epoxide (insect hormone substitute) and 2.4 g of tolylene diisocyanate are mixed. The mixture is then added to the open reaction vessel and emulsified with a high shear mesh bag. The resulting particles have a size of from 1 to 20 microns. To maintain balance, only mild agitation is required. In order to increase the rate of interfacial polymerization, the temperature of the reagents is raised to 50G for more than 15 minutes and at the same time the pH of the dispersion is maintained at 8.5 by the addition of 10% sodium hydroxide solution. The temperature and pH of the reaction mixture are maintained at 50 ° C. and 8.5, respectively, for 2 hours, in order to complete the interfacial polymerization; The pH of the product is 8.9. The product is cooled to room temperature. Example 5. Water (500 ml) containing 1.0% protective colloid - polyvinyl alcohol and 0.2% emulsifier - ethoxylate of alcoholic alcohol, is placed in an open reaction vessel. The temperature of this solution is raised to 40 ° C. In a separate container, 30 g of S-ethyl dipropyl thiocarbamate (herbicide) and 10 g of polymethylene polyphene-ene-isocyanate are mixed. The mixture is then added to the reaction vessel and emulsified with a high speed mixer. The temperature of the system is raised to 60 ° C and continued with a weak stirring for 1–1.2 hours, while: the temperature is maintained at 50 ° C. The material is filtered and washed three times and then dried at room temperature. Example 6. Water (500 ml) containing 3.0% hydroxypropyl methylcellulose protective colloid and 0.2% linear alcohol ethoxylate emulsifier is placed in an open reaction vessel. In a separate container, 150 g of S-ethyl dipropylthiocarbamate (herbicide), 35 g of polymethylene polyphenyl isocyanate, 17.5 g of tolylene diisocyanate and

005 g of tributyltin acetate as a catalyst. This mixture is then added to the reaction vessel and emulsified with a high speed stirrer. The resulting particles have a size of about 5 microns. To maintain the equilibrium of the reaction, only mild agitation is required. The temperature of the system is slowly raised to 50 ° C. The current is more than

1 1/2 hours At 50 ° C, significant foam formation occurs. The system is maintained at a temperature of 50 ° C for another 1 - 1/2 hour, after which it is cooled to room temperature. Microscopic examination of the system revealed discrete capsules of the correct shape.

Example 7. Water (500 ml) containing 3% polyacrylate protective colloid and 0.3% emulsifier — linear alcohol ethoxylate, is placed in an open reaction vessel. In a separate container, 30 g of S-ethylindo-butyl thiocarbamate (herbicide), 6.7 g of polymethylene polyphenyl isocyanate, and 3.3 g of tolylene diisocyanate are displaced. The organic phase is then added to the reactor and emulsified with a high shear blender. The resulting particles have a size of from about 1 to 10 mk. To maintain the equilibrium of the reaction, only mild agitation is required. The pH of the reaction medium is adjusted to 4.5 using conc. hydrochloric acid. The temperature of the reaction mixture is increased to 5 ° C and maintained for 3 hours. The system is cooled to room temperature. During the reaction, the pH of the medium remains 4.5. - - Example 8. Water (900 ml) containing 0.3% emulsifier-ethoxylate - linear alcohol is placed in an open reaction vessel. In a separate container, mix together 334 g of S-ethyldiisobutylthiocarbamate (herbicide), 20.7 g of polymethylene polyphenyl isocyanate Nta, and 20.7 g of gelendiisocyanate. The organic phase is then added to the reactor and emulsified with a high shear mixer. The resulting particles have a size of 5-15 microns. To maintain the equilibrium of the reaction, only a small amount of stirring is required. To the reaction mixture, 100 tons of 5.0% - aqueous saturated pacTBopai polyacrylamide colloid (A-370) are then added. The temperature of the reaction mixture is increased to bOS and, at the same time, the pH of the diuopsia is maintained at 8.5 by the addition of a 25% solution of sodium hydroxide. The temperature of the reaction mixture is maintained at 50 ° C and the pH is maintained at 8.5 to 3 hours in order to complete the interfacial polymerization. The reaction mixture is cooled to room temperature.

Example 9. This example illustrates the use of a high alkaline pH (13.6).

Water (500 ml) containing 2.0% protective hydroxypropylmethyl cellulose β-colloid, 0.2% linear alcohol ethoxylate emulsifier and 1.5% sodium hydroxide (pH 13.6 is placed in an open reaction vessel. In a separate container, mix together 160 g S - ethyldiisobutylthiocarbamate (herbicide), 35.0 g of polymethylene polyphenyl isocyanate, 17.5 g of tolylene diisocyanate and 0.05 g of tribol acetate. The aqueous phase is cooled to 9 ° C. Then the organic phase is added to the reaction vessel and emulsified with a blender. shear. All particles reduced in size to less than 40 microns. To maintain the equilibrium of the reaction, only gentle stirring is required. The temperature was slowly raised to room temperature (22 ° C). Stirring was continued for about 16 hours.

Example 10. This example illustrates the use of a high acid pH value (0.

Water (500 ml) containing 3.0% protective colloid of polyvinyl alcohol 510 0.3% emulsifier of linear alcohol ethoxylate, and 3.7% hydrochloric acid (pH 0) is placed in an open reactor. In a separate container, instead of 150 g of 5-p-propyldi- / g-propylthiocarbamate (herbicide), 17.7 g of polymethylene polyphenyl isocyanate and 8.8 g of tolylene diisocyanate are mixed. This mixture is then added to the reaction vessel and emulsified with a high shear blender. All particles: s were reduced to sizes below 15 microns. In order to maintain the equilibrium of the reaction, only a slight displacement is required. The temperature of the reagents is increased to 50 ° C over a period of 20 minutes. The temperature of the reaction mixture is maintained at 50 ° C for 2-1 / 2 hours to complete the interfacial polymerization. Example I; This example relates to the encapsulation of a water-insoluble material that can dissolve a significant amount of water, in this case 5.4%.

Water (500 ml) containing 1.0% poly .. acryl-amidogr. protective colloid and 0.3%

ethoxyld linear alcohol is placed in

open reaction vessel. Bi separate