DK144784B - encapsulation - Google Patents

Description

(19) DENMARK

| p (12, PREFACE SCRIPTURE <„) 14478¼B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. 1598/75 (51) IntCI.3 B 01 J 13/02 (22) Submission date 1 5 · niar · 1 975 (24) Running day 15 · mar. 1975 (41) Aim. available 1 Sep 6 1975 (44) Posted 7 Jun. 1982 (86) International application no. - (86) International filing day - (85) Continuation day (62) Master application no.

(30) Priority 15. weird. 1972, 25 ^ 795 * US 12 · Jan. 1975 * 525171, US

(71) Applicant STAUFFER CHEMICAL COMPANY, Westport, US.

(72) Inventor Herbert Benson Scher, US.

(74) Associate Company Chas. Hude.

(54) The way of encapsulation.

Process for encapsulating a hydrophobic liquid or solution in a polyurea wrapper.

The invention relates to a method for encapsulating a hydrophobic liquid or solution in a polyurea enclosure.

The invention is for the manufacture of small or very small capsules having a membrane or thin wall and a body of some material, e.g. a liquid.

The Capsules have a variety of uses, such as for the containment of colorants, inks, chemical reagents, pharmaceuticals, flavors, fungicides, bactericides and pesticides such as herbicides, insecticides and the like, which may be dissolved, suspended or otherwise dispersed in or as the material to be enclosed by the capsule.

2 144784

The material to be encapsulated can be used in the original dispersion at a temperature above its melting point, or dissolved or dispersed in suitable organic solvents which are immiscible with water. The nature of the water-immiscible material to be encapsulated may in its origin be organic or inorganic. When the material is encapsulated, the liquid or other form is maintained until released by certain aids or instruments which break, crush, melt, dissolve or otherwise remove the capsule skin or until release by diffusion under appropriate conditions. A particularly important feature of the present invention, along with other features and advantages of the present invention, is the process of polymerization which involves the reaction of polyisocyanate monomers to form a capsule skin of polyurea.

A variety of methods have been used or described for encapsulation purposes in the past. Among these are the process in which the enclosing film is deposited by condensation, and other methods involving polymerization of a substance contained in droplets or in a surrounding continuous liquid phase such that the resulting polymer is deposited on the surface of such droplets. Another approach involves shooting droplets through a falling film of liquid capsule wall material, which then solidifies around the individual droplets. Various methods of encapsulation by interface condensation between directly acting complementary reagents are known. Among these methods are reactions to prepare various types of polymers such as capsule walls. Many such reactions for the preparation of the coating occur between an amine which must have the least difunctional character and another reacting intermediate of acid or, more specifically, the acid-derived character, which for the preparation of a polyamide is a difunctional or poly-functional acid chloride. The most commonly used or suggested amines in these processes are exemplified by ethylenediamine or the like with at least two primary amino groups.

Finally, for many encapsulation methods, there is a requirement that the encapsulated materials be separated from the formation medium. During this treatment process, the capsule wall material is subjected to high stresses and stresses. For this reason, the much desired thin skin or cell wall is extremely limited by methods known in the art. A particular object of the present invention is to provide a novel and improved encapsulation method which is fast and efficient and avoids the necessity of separation of the encapsulated material. A particular advantage is therefore the possible formation of extremely thin skin or cell wall in connection with the capsules.

Interface polymerization usually implies that two immiscible liquids, e.g. water and organic solvent, respectively, containing complementary, direct-acting organic intermediates, which will react with each other to provide a solid polycondensate, are brought together. Such polycondensates, such as a polyamide, a polyester, a polyurethane, a polyurea, or similar substances can be formed from resin intermediates or monomers. It has also been proposed to spray droplets of organic solvent containing a diacid chloride into an aqueous liquid containing e.g. ethylene glycol for the purpose of encapsulating the organic liquid or oil in polyester capsules. However, these trials have had little practical value in various respects.

For example, a special apparatus for this method. Furthermore, various experiments have shown the difficulty of providing the desired capsules in discrete form, whereby the partially formed capsules will be fused to a heterogeneous mass of material lacking separate capsule formation. Capsule size control or uniformity is troublesome in prior art methods. The procedures appear to be limited by the reaction types and the products in question. A special encapsulation method for interface polycondensation is described in U.S.A. U.S. Patent 3,577,515, issued May 4, 1971. This patent discloses a continuous or portion process requiring a first reactant and a second reactant complementary to the first reactant with each reactant in a separate phase so that the first and the second reactant reacts at the interface between the droplets to form encapsulated droplets. As will be apparent from the following, the present invention removes the need for another reactant, as it has been found that a polyurea type encapsulating mass can be formed with great ease and confer particular advantages.

4 1U784

The process according to the invention is characterized in that a) a solution is prepared in an aqueous phase containing water and optionally a surfactant, preferably 0.01-3.0% by weight, based on the aqueous phase, b) this aqueous phase an organic phase is added which comprises the hydrophobic material to be encapsulated and a polyisocyanate, preferably an aromatic polyisocyanate or a mixture of polyisocy. anates, c) the organic phase is dispersed in the aqueous phase to form droplets of the organic phase in the aqueous phase, and d) a protective colloid, preferably 0.1-5.0% by weight, based on the aqueous phase, is added either by preparing the aqueous phase or after the dispersion.

Contrary to the known methods and corresponding to a preferred embodiment of the invention, an effective encapsulation is obtained by the interfacial polymerization of a di- or polyisocyanate by a process in which two substantially immiscible liquids are added, one of which is is an aqueous and the other an organic phase from which a dispersion is prepared and the organic phase contains the isocyanate to form the capsule wall of polyurea. In the process of the invention for the formation of the capsule wall by interface polymerization, an isocyanate monomer is hydrolyzed to form an amine which in turn reacts with additional isocyanate monomers to form the polyurea envelope. During the hydrolysis of the isocyanate monomer, CC 2 is released.

Once the dispersion leading to the formation of organic phase droplets has been prepared, a homogeneous liquid phase, i.e. in the aqueous phase, no additional reaction component is required. Following the preparation of the dispersion, the formation of the polyurea envelopes on the dispersed droplets is effected by heating the homogeneous liquid phase or by introducing a catalytic amount of an amine or other substance which accelerates the rate of light of the isocyanate, such as e.g. . tri-n-butyltin acetate, wherein further the pH of the dispersion can be adjusted at any time to the desired value, including the desired condensation reaction at the interfaces between the phases.

In this way, in any respect, fully satisfactory single capsules are formed, the wall of which consists of the polyurea formed in the reaction and which contains the organic phase. In the process of the invention, the reaction which forms the capsule wall is generally complete, leaving essentially no unreacted polyisocyanate. For many applications, it is not necessary to separate the capsules from the homogeneous phase, ie. the wrapped material can be used directly. However, a separation prior to use may be effected by any of the normal separation methods comprising e.g. precipitation, filtration or foaming of the total capsules, washing and desired drying. The product obtained by the process according to the invention is particularly well suited for direct use to control harmful organisms to which additional substances such as thickeners, biocides, surfactants, dispersants can be added to improve storage stability and facilitate use. As aids in the preparation of the initial dispersion of the organic phase in the aqueous phase, a suitable emulsifying or dispersing aid may be added and a control of the process with respect to the size and homogeneity of the finally obtained capsules may be effected by means of of conventional methods applicable to dispersing one liquid in another.

Three preferred embodiments of the method according to the invention for preparing capsule dispersions are shown in the block diagrams shown in the drawing. 1, FIG. 2 and FIG. Third

In carrying out the method according to the invention, it is always stated that first, e.g. by simple stirring, prepares a solution containing water, a suitable surfactant and a protective colloid. These three components form the aqueous or homogeneous phase of the process. The aqueous phase contains substantially no constituents which can in any way react with material contained in the aqueous phase, or a group of such materials. The aqueous phase surfactant and protective colloid do not participate in the polycondensation reaction at which the capsule wall is formed.

As a further example, in the aqueous or continuous phase, the surfactants can be described as nonionic, anionic or cationic surfactants in the HLB (hydrophilic-lipophilic balance) range of approx. 12 to approx. 16. There are many surfactants that meet this HLB area requirement. Among the acceptable surfactants are the compounds known as sodium isopropylinaphthalenesulfonate, polyoxyethylene sorbitol oleate laurate and ethoxylated nonylphenols, however, the preferred surfactants are of the polyethylene glycol ethers of linear alcohols. Although the surfactant herein is described as being in the aqueous phase, it can also be applied to the organic phase. Without particular reference to the phase in which the surfactant is placed, there will be a division and distribution of the surfactant between each phase after mixing of the phases, depending on the relative solubility therein. The use of a surfactant can be omitted, provided that a sufficiently high shear rate is used to form the dispersion.

In the preferred embodiment of the present invention, a surfactant is used. The range of surfactant concentration, which has proven most acceptable in this system, is from ca. 0.01 to approx. 3.0% by weight of the aqueous phase. Higher surfactant concentrations can be used without increased dispersion ease.

In the aqueous or continuous phase, there is also a protective colloid which may be selected from a wide variety of such materials. The useful protective colloids can be exemplified by the following: Polyacrylates, methyl cellulose, polyvinyl alcohol, polyacrylamide and poly (methyl vinyl ether / maleic anhydride). The amount of colloid used will depend on various factors such as molecular weight, nature and efficiency of the medium, compatibility and the like. It has been found that the protective colloid can be added to the aqueous phase prior to the addition of the organic phase to the aqueous phase. Alternatively, the protective colloid may be added to the system after the addition of the organic phase or after its dispersion. As another alternative, the protective colloid may be added partially prior to the addition of the organic phase and partly after the dispersion step. It is usually used from approx. 0.1 to approx. 5.0% by weight based on the aqueous phase.

Another phase, referred to as the organic phase, comprises the material to be encapsulated and a polyisocyanate. The material to be encapsulated can be used in a concentrated form or in a solution of a water-immiscible solvent. The material to be encapsulated can be used as the solvent for the polyisocyanate.

However, to obtain a desired concentration of active material in the final product, a water-immiscible organic solvent can be used to dissolve the material to be encapsulated and the polyisocyanate. The material to be encapsulated and the polyisocyanate are simultaneously added to the aqueous phase. Although the material to be encapsulated and the polyisocyanate can be added separately with slow stirring in the reaction vessel for a period of time sufficient to cause a homogeneous organic solution, the preferred method is the simultaneous addition of the organic phase components in a premixed state. That is, the material to be encapsulated and the polyisocyanate are premixed to obtain a homogeneous phase prior to addition to and mixing with the aqueous phase. The amount of the organic phase can vary from approx. 1 to approx. 75 volumes of the aqueous phase present in the reaction vessel. Concentrations in the lower part of this range are relatively undesirable as they give a very dilute capsule suspension. The preferred amount of organic phase is approx. 25 to approx. 50 volumes ^.

The nature of the organic polyisocyanate determines the release properties of the capsule formed by this process. The polyisocyanates further determine the structural physical strength of the capsule skin.

The organic polyisocyanates contemplated by this process include those members of the aromatic polyisocyanate class which comprise the aromatic diisocyanates, the aliphatic diisocyanate class, high molecular weight aliphatic diisocyanates and isocyanate prepolymers. Representatives of the aromatic diisocyanates and the other polyisocyanates are as follows:

q U478A

ISLAND

1-Chloro-2,4-phenylene diisocyanate m-phenylenedii so cyanate p-phenylene diisocyanate 4,4'-methylenebis (phenylisocyanate) 2,4-tolylene diisocyanate thiolene diisocyanate (60% 2,4-isomer, 40% 2,6-isomer) 2,6-tolylene diisocyanate 3,3'-dimethyl-4,4'-biphenylene diisocyanate 4,4'-methylenebis- (2-methylphenylisocyanate) 3,3'-dimethoxy-4,4 * -biphenylene diisocyanate 2,21,5,5 -tetramethyl-4,4'-biphenylene diisocyanate 80% 2,4- and 20% 2,6-isomer of tolylene diisocyanate p olymethylene polyphenyli cyanate (PAPI).

It is highly desirable to use combinations of the above-mentioned organic polyisocyanates. Such combinations, e.g. polymethylene polyphenyl isocyanate and tolylene diisocyanate containing 80% 2.4- and 20% 2.6-isomers provide excellent capsule inclusions with uniquely controlled release properties.

The amount of organic polyisocyanate used in the process will determine the wall content of the capsules formed thereby. Generally, on the basis of the organic phase, there will be more than approx. 2% by weight of organic polyisocyanate present. However, this is by no means limiting and a greater amount approaching 100% can be used. Of course, 100% will not be completely desirable as this will result in a product without encapsulated material. The preferred range is from approx. 2.0 to approx. 75% by weight of organic polyisocyanate, thereby forming an encapsulated material having a corresponding wall content, i.e. ca. 2.0 to approx. 75.0%. The preferred range is specified from ca. 5.0 to approx. 50.0% wall content.

In the process of the invention, which uses the two essentially immiscible phases described above, the preferred embodiments proceed according to the following general process steps: essentially, a dispersion of the organic phase in the aqueous (homogeneous) phase is prepared. ) phase, whereby droplets of the organic phase of the desired size are dispersed in the aqueous phase. The desired condensation reaction is then effected by adjusting the pH of the resulting mixture and the temperature within the appropriate temperature range on the interfaces between the droplets and the continuous phase. 1. Certain variations in the order of the steps between adjusting the pH and applying the required heat will appear in the following discussion and the following examples.

The temperature of the two-phase mixture, i.e. the dispersion of the organic phase in the aqueous phase is raised to approx. 40-60 ° C. The temperature range of the condensation reaction of the present invention is between ca.

20 and approx. 90 ° C. Although the heat to initiate the reaction can be applied to the dispersion of the organic phase in the aqueous phase at the same time or after adjusting the pH to the desired value, the aqueous phase can be heated to the required temperature prior to the addition steps of the organic phase and the dispersion. . 3. In this alternative method, the pH is adjusted after the dispersion has occurred and the pH is kept within the limits discussed below.

In one embodiment of the present invention, FIG. 2, it has been found that a catalyst capable of increasing the rate of isocyanate hydrolysis, e.g. of the basic amine type, to the organic phase or the aqueous phase prior to the initiation of the desired condensation reaction. However, this step is not necessary for the successful practice of the present invention. When it is chosen to substitute a catalyst with increase in the temperature of the process, the product thus obtained is comparable to a non-catalyzed system. Increased temperature and catalyst can be used simultaneously to effect the desired polycondensation reaction. The catalyst in such a process is preferably added to the organic phase and added at the time the aqueous and organic phase are mixed. Various catalysts have proved acceptable, their choices will depend on factors which can be readily determined by those skilled in the art. It has been found that certain basic organic amines, preferably tertiary amines and alkyltin acetates, such as tributyltin acetate and di-n-butyltin diacetate of IU78Å are acceptable catalysts. When an alkyl tin acetate is used, approx. 0.001 to approx. 1.0% by weight based on the organic phase. Included in the basic organic tertiary amines are triethylenediamine, N, N, Nr, N'-tetrarnethyl1-1,3-butane diamine, triethylamine, tri-n-butylamine and the like. The amount of catalyst will vary with the particular system and conditions. When a basic organic amine is used, approx. 0.01 to approx. 10.0% by weight based on the organic phase.

It will often be found that water is slightly soluble in the water-immiscible material to be encapsulated. The amount of water that will be dissolved in the material to be encapsulated will depend on the nature of the material. The amount of dissolved water will usually be relatively small. However, using a water-immiscible material capable of dissolving a significant amount of water, a slight deviation from the normal methods described herein is preferred. It has been found in such a system that particles with poorly defined wall structure appear. Well-defined microcapsules which fall within the scope of the present invention can be prepared by adding a suitable catalyst to the aqueous phase after the emulsion is formed. The mass polymerization thus takes place on the interface where the catalyst is present. No heating of the mixture is recommended, otherwise polymer will not form only on the surface, but an increased amount will form in the water-immiscible material which can dissolve a significant amount of water. This process is preferably carried out at room temperature (15-30 ° C).

This process of adding catalyst to the aqueous phase after the dispersion is not limited to encapsulation of water-immiscible alone which can dissolve a significant amount of water, but finds general use in connection with any water-immiscible material which will be discussed and described in the following.

By the method of the invention, the aqueous phase is most conveniently prepared as described above. The organic phase is preferably added in the premixed state with stirring to the aqueous phase. After adding the organic phase to the aqueous phase, a suitable dispersing aid is used to disperse one liquid into another. Conveniently, any large displacement equipment can be used to obtain the desired droplet size in the range of from approx. 0.5 microns to approx. 4000 microns. The current range will depend on the end use you want. The preferred area for most pesticidal applications is e.g. from approx. 1 micron to approx. 100 microns. The present method can be used to make capsules of very varied but uniform size. When the appropriate droplet size is obtained, the dispersing aid used to provide the desired droplet size is discontinued. Only slight agitation is required for the rest of the process.

The process of the invention can provide satisfactory performance and production of encapsulated material without adjustment to a particular pH value. That is, no adjustment of the pH of the system is required during the encapsulation process. The encapsulation method will proceed at a pH value between approx. 0 and approx. 14. The desirability of adjusting the pH to a particular value will depend on the nature of the components of the system, such as surfactant, colloid, catalyst, temperature, material to be encapsulated, and the like. If the pH is allowed to drop below approx. 7.0, carbon dioxide, e.g. be released during the course of the reaction. If it is desirable to avoid this evolution of carbon dioxide, the adjustment can be made to a pH value of at least approx. 7.0. In the embodiment of FIG. 1 and 2, the pH is adjusted to the dispersion and maintained at this value during the remainder of the condensation reaction. The pH adjustment can take place in the aqueous phase prior to the addition and dispersion therein of the organic phase. The setting and maintenance of a particular pH during the reaction can be carried out with various water-soluble bases or acids which cannot react with the polyisocyanate intermediate. Concentrated sodium hydroxide (25% solution), potassium hydroxide, hydrochloric acid and the like are preferably used.

The evolution of carbon dioxide can cause significant undesirable foaming and / or volume expansion which adversely affects the processing of the reaction mixture. An alternative to adjusting the pH to avoid the excess foam formed by the evolution of carbon dioxide is the addition of an antifoaming agent. By using an antifoaming agent, it is possible to prepare the encapsulated material satisfactorily at an acidic pH without adding base to the acidic system. The anti-foaming agent may be added at any time during the processing of the mixture when said polymer capsule enclosures are formed to encapsulate a water immiscible material.

Although the desired condensation reaction at the interface between the droplets and the continuous phase occurs very rapidly, most during the first half hour of reaction time, the reaction conditions are continued in order to ensure almost completion of the condensation reaction in the system, approx. 2-3 hours. Under appropriate conditions or with a suitable catalyst, the reaction time can be shortened. At the end of this time, the formation of a capsule wall is completed, thereby enclosing organic matter in a skin of a polycondensate and a usable encapsulated product exists. A particular feature of the present invention, which is highly desirable, lies in the fact that for certain contemplated uses, no further separation or treatment of the encapsulated material is required, i.e., that the product can be used directly. The encapsulated material can be used for various direct applications at this time or indirectly by inserting the material into other products.

The thickness or chemical composition of the capsule wall can be selected or controlled in various ways. These properties can e.g. is influenced by the control of the reaction condition, by chemical choice, especially by the formation of crosslinking, which is determined by the functionality of the polyisocyanate of the invention. The thickness of the capsule skin may also be affected by varying the amounts of reactants in the organic phase. A convenient method of controlling the size of the capsule is to adjust the agitation rate, i.e., by providing the initial dispersion of the organic phase, smaller capsules with higher agitation rates can be obtained, resulting in a greater shear force.

Tests have shown that capsules made according to the invention can be used in the same way as products made by other encapsulation methods. Thus, encapsulated herbicides or insecticides may e.g. incorporated into dispersions for use in controlling the release of the encapsulated material at the desired site. Particular attention should be paid to the encapsulation of various volatile or unstable insecticides and herbicides. When encapsulated, premature evaporation or other destruction of the material is avoided.

Such encapsulation can also serve for the purpose of delaying or prolonging the duration of operation when desired. Controlled release of these materials is important for environmental protection and the appropriate effect on the organism to be controlled, as well as reduced toxicity to beneficial organisms.

The process according to the invention can be carried out as a continuous or continuous process or as a combination thereof.

If the process according to the invention is carried out discontinuously, all the various liquids and reaction components are brought together and the various reaction steps are carried out in the appropriate order in this amount of liquid. The continuous process can be modified so that suitable reaction vessels are used to obtain a continuous or an embodiment of the encapsulation method corresponding to this embodiment. In the continuous form of the process according to the invention, the dispersion and stirring of the reacting phases can be carried out at an appropriate rate continuously so that a suitable dispersion of droplets in the homogeneous phase is continuously obtained and that an amount of this dispersion of droplets in a homogeneous phase is obtained. is continuously delivered to a reaction vessel in which the pH value adjustment and the amount of heat required to obtain the condensation can be carried out. In the continuous form, the appropriate reaction rate can be set by selecting the corresponding manufacturing conditions. Both the discontinuous and the continuous form of the process are very favorable so that the choice depends only on the desired manufacturing conditions.

Example 1.

Water (500 ml) containing 1.0% neutralized protective poly (methyl vinyl ether / maleic anhydride) colloid (Gantrez AN 139 ") and 0.2% linear alcohol ethoxylate C emulsifier (" Tergitol 15-S-20 ") is placed in an open reaction vessel In a separate container, 167 g of O-ethyl-S-phenylethylphosphone dithioate (an insecticide), 39 g of polymethylene polyphenylisocyanate (PAPI) and 19.5 g of tolylene diisocyanate (TDI 80% 2.4 and 20% 2) are mixed. This mixture is then added to a reaction vessel and emulsified with a high shear stirrer, the resulting particle size range is about 1-20 microns, only slight stirring is required for the remainder of the reaction, the temperature of the reactants is raised to 50 ° C. for a period of 17 minutes, and at the same time the pH of the dispersion is maintained at 8.5 by the addition of 25% sodium hydroxide solution, the temperature of the reaction mixture is maintained at 50 ° C and the pH is maintained at 8.5 for 2¾ hours to complete the interface polymerization.

At this point, e.g. 0.25% sodium bentonite thickener and 0.05% sodium pentachlorophenate biocide are added to form the product without separation or further washing.

The pH of the preparation is usually adjusted to 9.75 by adding 25% NaOH solution and the reaction mixture is cooled to room temperature. These preparations are very well dispersed in water and discrete capsules are observed under a microscope. The capsules have a wall content of approx. 26%.

Example 2.

Water (500 ml) containing 1.5% protective hydroxypropyl methyl cellulose loose colloid ("Methocel 65HG") and 0.2% linear alcohol ethoxylate emulsifier ("Tergitol 15-S-20") is placed in an open reaction vessel. 150 g of S-ethyldiiso = butylthiocarbamate (a herbicide), 35 g of polymethylene polyphenyliso cyanate (PAPI), 17.5 g of tolylene diisocyanate (TDI 80% 2.4 and 20% 2.6) and 0.05 g of tributyltin acetate catalyst. then to the reaction vessel and stirred with a high speed stirrer.The resulting particle size range is about 1-20 µ.

Only slight stirring is required for the rest of the reaction. The pH of the reaction mixture is now adjusted to 8.0 with 10% sodium hydroxide solution. This pH is maintained for 3 hours by continued addition of 10% sodium hydroxide solution. The presence of the catalyst allows the interface polymerization to be carried out at room temperature (25 ° C). This preparation is very well dispersed in water and discrete capsules can be observed under a microscope. These capsules have a wall content of approx. 26%.

15

Example 3

144784

Water (500 ml) containing 0.5% "protective polyacrylamide colloid (" Cyanamer A370 ") and 0.2% linear alcohol ethoxylate (" Tergitol 15-S-20 ") is placed in an open reaction vessel. In a separate container, 167 g of O -ethyl-S-phenylethylphosphone dithioate (an insecticide), 14.5 g of polymethylene polyphenyl isocyanate (PAPI) and 14.5 g of tolylene diisocyanate (TDI 80% 2.4 and 20% 2.6). The aqueous phase of the open reaction vessel is heated. to 45 ° C, then the organic mixture above is added to the reaction vessel and emulsified with a high shear stirrer, at which point the pH equals about 6.5 The resulting particle size range is 1-20 µm. The pH of the reaction mixture is adjusted to 8.5 with 25% sodium hydroxide solution. The temperature of the reaction mixture is adjusted to 50 ° C. The temperature and pH of the reaction mixture are maintained at 50 ° C and 8.5 for 3 hours, respectively, to complete the interface polymerization. held at 8 , 5 by continued addition of 25% sodium hydroxide solution. At this point, 0.25% sodium bentonite thickener can be added to the capsule dispersion and the pH is adjusted to 9.8 to form the encapsulated material without further separation or treatment. The preparation is cooled to room temperature. This preparation can be easily dispersed in water and discrete capsules can be observed under a microscope. These capsules have a wall content of approx. 15%.

Example 4

Water (100 ml) containing 3% protective polyacrylate colloid ("Goodrite K-718") and 0.2% linear alcohol ethoxylate emulsifier ("Tergitol 15-S-20") is placed in an open reaction vessel. In a separate container, 30 g of 4'-ethylphenylgeranyl ether-6,7-epoxide (insect hormone-like) and 2.4 g of tolylene diisocyanate (TDI 80% 2.4- and 20% 2.6-) are mixed together. This mixture is then added to the open reaction vessel and emulsified with a high shear stirrer.

The resulting particle size range is 1-20 μ. Only slight stirring is required for the rest of the reaction. To increase the rate of the interface polymerization, the temperature of the reactants is now raised to above 50 ° C for a period of 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 for 2 hours, respectively, to complete the interface polymerization. The pH of the preparation is adjusted to 8.9. The preparation was cooled to room temperature. This preparation is very well dispersed in water and discrete capsules can be observed under a microscope. These capsules have a wall content of approx. 7.4%.

Example 5

Water (500 ml) containing 1.0% protective polyvinyl alcohol colloid ("Vinol 540") and 0.2% linear alcohol ethoxylate emulsifier ("Tergitol 15-S-20") is placed in an open reaction vessel. The temperature of this solution is raised to 40 ° C. In a separate container, 50 g of S-ethyl dipropylthiocarbamate (a herbicide) and 10 g of polymethylene polyphenyl isocyanate (PAPI) are mixed together. This mixture is then added to the reaction vessel and emulsified with a high speed stirrer. The temperature of the system is then raised to 60 ° C and gentle stirring is continued for 1½ hours while maintaining the temperature at 50 ° C. The material is then filtered off and washed three times and allowed to dry at room temperature. Microscopic examination shows discrete spheroid particles. The capsules have a wall content of 25% ·

Example 6

Water (500 ml) containing 3.0% protective hydroxypropyl methyl cellulose colloid ("Methocel 65 HG") and 0.2% linear alcohol ethoxylate emulsifier ("Tergitol 15-S-20") is placed in an open reaction vessel. In a separate container, 150 g of S-ethyl dipropyl = thiocarbamate (a herbicide), 35 gp olymethylene polyphenylsocyanate (PAPI), 17 * 5 g tolylene diisocyanate (TDI 80% 2.4- and 20% 2.6-) and 0 are mixed. 05 g of tributyltin acetate catalyst. This mixture is then added to the reaction vessel and emulsified using a high speed stirrer. The resulting particle size is approx. 5 microns.

Only slight stirring is required for the rest of the reaction. The temperature of the system is slowly raised to 50 ° C over 1Ί hours. At 50 ° C considerable foaming took place. The system is kept at 50 ° C for an additional 1½ hours, after which it is cooled to room temperature. Microscopic examination of the system revealed discrete, well-shaped capsules. These capsules have a wall content of 26%.

U4784

Example 7

17

Water (500 ml) containing 3% protective polyacrylate colloid ("Good-rite K-718") and 0.3% linear alcohol ethoxylate emulsifier ("Tergitol 15-S-7") is placed in an open reaction vessel. In a separate container, 30 g of S-ethyl diisobutylthiocarbamate (a herbicide), 6.7 g of polymethylene polyphenyl isocyanate (PAPI) and 3.3 g of tolylene diisocyanate (TDI 80% 2.4 and 20% 2.6) are mixed. The organic phase is then added to the reaction vessel and emulsified with a high shear stirrer. The resulting particle size range is approx. 1-10 µ. Only slight stirring is required for the rest of the reaction. The pH of the reaction mixture is adjusted to 4.5 with concentrated hydrochloric acid. The temperature of the reaction mixture is raised to 50 ° and maintained at this temperature for 3 hours. The system is cooled to room temperature. The pH remained at 4.5 during the course of the reaction. This product can be easily dispersed in water and discrete capsules can be observed under the microscope. These capsules have a wall content of approx. 25%.

Example 8.

Water (900 ml) containing 0.3% linear alcohol ethoxylate emulsifier ("Tergitol 15-S-7") is placed in an open reaction vessel. In a separate container, 334 g of S-ethyl diisobutylthiocarbamate (a herbicide), 20.7 g of polymethylene polyphenyl isocyanate and 20.7 g of tolylene diisocyanate (TDI 80% 2.4 and 20% 2.6) are mixed. The organic phase is then added to the reaction vessel and emulsified with a high shear stirrer. The resulting particle size range is 5-15 μ. Only slight stirring is required for the rest of the reaction. 100 g of 5.0% aqueous solution of protective polyacrylamide colloid ("Cyanamer A-370") is then added to the reaction mixture. The temperature of the reaction mixture is raised to 50 ° C and at the same time the pH of the dispersion is maintained at 8.5 by the addition of 25% sodium hydroxide solution. The temperature of the reaction mixture is maintained at 50 ° C and the pH is maintained at 8.5 for approx. 3 hours to complete the interface polymerization. The reaction mixture is cooled to room temperature. The reaction mixture can be easily dispersed in water and discrete particles can be observed under the microscope. These particles have a wall content of approx. 11%.

Example 9

18 144784

This example "illustrates the use of a very basic pH (i.e., pH = 13.6).

Water (500 ml) containing 2.0% protective hydroxypropyl methyl cellulose colloid ("Methocel 65 HG, r), 0.2% linear alcohol ethoxylate emulsifier (" Tergitol 15-S-20 ") and 1.5% sodium hydroxide (pH = In a separate container, 150 g of S-ethyl diisobutylthiocarbamate (a herbicide), 35.0 g of polymethylene polyphenyl isocyanate (PAPI), 17.5 g of tolylene diisocyanate (TDI 80% 2.4 and 20% 2) are mixed together. , 6) and 0.05 g of tributyltin acetate The aqueous phase is cooled to 9 DEG C. The organic phase is then added to the reaction vessel and emulsified with a high shear stirrer.

All particles were reduced to below 40 μ in size. Only slight stirring is required for the rest of the reaction. The temperature was allowed to rise slowly to room temperature (22 ° C). Stirring was continued for approx. 16 hours. Discrete particles were observed under a microscope. The particles have a wall content of approx. 25%.

Example 10.

This example illustrates the use of a very acidic pH (i.e., pH = 0).

Water (500 ml) containing 3.0% protective polyvinyl alcohol colloid ("Vinol 540"), 0.3% linear alcohol ethoxylate emulsifier ("Ter = gitol 15-S-7") and 3.7% hydrochloric acid (pH = 0) is applied. an open reaction vessel. In a separate container, 150 g of Sn-propyl di-n-propylthiocarbamate (a herbicide), 17.7 g of polymethylene polyphenyl = isocyanate (PAPI) and 8.8 g of tolylene diisocyanate (TDI 80% 2.4 and 20% 2.6) are mixed. ). This mixture is then added to the reaction vessel and emulsified with a high shear stirrer. All particles were reduced to below 15 μ in size. Only slight stirring is required for the rest of the reaction. The temperature of the reactants is raised to 50 ° C over 20 minutes. The temperature of the reaction mixture is kept at 50 ° C for 2 - hour to complete the interface polymerization. Discrete particles were observed under a microscope. The capsules had a wall content of approx. 15%.

Example 11.

U4784 19

This is an example of encapsulating water-immiscible material that can dissolve a significant amount of water, in this case 5.4%.

Water (500 ml) containing 1.0% protective polyacrylamide colloid ("Cyanamer A370") and 0.3% linear alcohol ethoxylate ("Tergitol 15-S-20") is placed in an open reaction vessel. In a separate container, 33.4 g of tris-p-chloroethyl phosphate (an anti-inflammatory agent), 4.0 g of polymethylene polyphenyl isocyanate (PAPI) and 2.0 g of tolylene = diisocyanate (TDI 80% 2.4 and 20% 2.6) are mixed. . The mixture is then added to the reaction vessel and emulsified with a high shear stirrer. The resulting particle size range is 2-15 μ. Only slight stirring is required for the rest of the reaction. At this point, 1.0 g of triethylenediamine catalyst dissolved in 10 ml of water is added to the aqueous phase and the pH is adjusted to 9.5. The pH is maintained at 9.5 by the addition of 25% sodium hydroxide solution and stirring is continued at room temperature (about 25 ° C) for 17 hours. Discrete, well-shaped microcapsules were observed under a microscope. The capsules have a wall content of 15%.

Example 12.

This example illustrates the encapsulation of a normal solid by enclosure formation around a water-immiscible solvent in which the solid is dissolved.

Water (500 ml) containing 2.0% hydrolyzed protective poly (methyl = vinyl ether / maleic anhydride) colloid ("Gantrez AN119") and 0.3% linear alcohol ethoxylate emulsifier ("Tergitol 15-S-7") is placed in an open reaction vessel. The pH of this solution is adjusted to 4.5. In a separate container, 167 g of a 30% solution of N- (mercaptomethyl) -phthalimide-S- (O-dimethylphosphorodithioate) (an insecticide having a melting point of 72 ° C) is mixed in a heavy aromatic naphtha solvent ("Panasol" AN-3 "), 8.3 g of polymethylene polyphenylisocyanate (PAPI) and 4.2 g of tolylene diisocyanate (TDI 80% 2.4 and 20% 2.6). This mixture is then added to the reaction vessel and emulsifier

14478A

be done with a large displacement stirrer. All particles are reduced to a size below 20 µ. Only slight stirring is required for the rest of the reaction. The temperature of the reactants is raised to 50 ° C over 20 minutes. The temperature of the reaction mixture is maintained at 50 ° C for 2¾ hours to complete the interface polymerization. The preparation is very well dispersed in water and discrete capsules were observed under a microscope. The capsules have a wall content of approx. 7.5%. Insecticide crystals were not observed under a microscope after the preparation was stored at room temperature for 2 days.

Example 13

This example illustrates the encapsulation of two water-immiscible substances in the organic phase.

Water (500 ml) containing 0.5% protective polyacrylamide colloid ("Cyanamer A370") and 0.3% linear alcohol ethoxylate ("Tergitol 15-S-7") is placed in an open reaction vessel and the pH is adjusted to 8.5. In a separate container, 138.5 g of S-ethyl dipropylthiocarbate (an herbicide), 11.5 g of Ν, Ν-diallyldichloroacetamide (a herbicide antidote), 35.0 g of polymethylene polyphenylisocyanate (PAPI) and 17.5 g of tolylene diisocyanate (TDI) are mixed. % 2.4 and 20% 2.6). This mixture is then added to the open reaction vessel and emulsified with a high shear stirrer. The resulting particle size range is 5-30 µ. Only slight stirring is required for the rest of the reaction. The reaction mixture is then heated to 50 ° C over 26 minutes. The reaction mixture is kept at 50 ° C for 2¾ hours. The pH is maintained at 8.5 by the addition of 25% sodium hydroxide solution. This preparation is very well dispersed in water and discrete microcapsules can be observed under a microscope. These capsules have a wall content of approx. 25%.

As previously mentioned and illustrated by way of the examples, the encapsulation method of the present invention provides capsules with a controlled release of encapsulated organic material. By way of example and of particular importance are the process and capsules comprising as an ingredient in the organic phase, herbicides of the thiocarbamate class, such as S-ethyl diisobutylthiocarbamate, S-ethyl dipropylthiocarbamate, S-ethylhexahydro-1H-az epin-1-carb othi o that, S-propyl-hexahydro-1 H -carb othi o, S-propyl-dipropylthio carbamate, S-ethyl-ethyl-cyclo = hexyl-thiocarbamate, S-propyl-butylethyl-thiocarbamate, organic phosphorous insecticides of the organic species phosphone and phosphorothioates and dithioates such as O-ethyl-S-phenyl-ethyl-phosphone dithioate, S- / T-chlorophenylthio) methyl7-0,0-dimethyl phosphorus dithioate, S- (~ p-chloro = phenylthio) methyl7-0 , O-diethylphosphorous dithioate, O, O-dimethyl-Op-nitrophenyl phosphorothioate, 0,0-diethyl-O-p-nitrophenyl phosphorothioate, and insect hormones and the like, such as

Cecropia - juvenile hormone - I

1- (4'-Ethyl) -phenoxy-5,7-dimethyl-6,7-epoxy-trans-2-octene 1- (3'-''-methylenedioxy) -phenoxy-5,7-dimethyl-6, 7-epoxy-trans-2-nonene

Ethyl 5,7,11-trimethyldodeca-2,4-dienoate Isopropyl-11-methoxy-5,7,11-trimethyl-dodeca-2,4-dienoate

Claims (2)

Capsules with compounds which can be used for plant disease control provide a method for long-term disease control using compounds which are generally considered to be effective only for a short time. Similarly, herbicides, nematocides, insecticides, rat exterminators, and soil nutrients can be encapsulated with useful results. Chemicals used for seed treatment can also be readily encapsulated by the process of the invention. Other biological products may be encapsulated including: Intestinal worms, lamps and mucus controllers, algicides, swimming pool chemicals, mites, acaracides, animal attractants, antiseptics, deodorant, disinfectants, mildew and the like. The material to be encapsulated using the method of the invention may be of any kind immiscible with water. The material need not only consist of one type, but may be a combination of two or more types of water immiscible materials. Such a combination is e.g. using a suitable water immiscible material, a herbicide and an effective insecticide. In addition, a water-immiscible material to be encapsulated which comprises an active ingredient such as a herbicide and an inert ingredient such as a solvent or excipient is also contemplated. Encapsulation of a solid can be accomplished by this process by forming a solution of the solid in a suitable solvent. Thereby a normal solid with water immiscible material can be encapsulated. Eg. For example, the insecticide N- (mercaptomethyl) -phthalimide-S- (0.0-dimethyl = phosphorodithioate), melting point 72 ° C, can be encapsulated by first dissolving the solid in a suitable solvent, such as a heavy aromatic naphtha solvent. Claims. A method of encapsulating a hydrophobic liquid, or solution, in a polyurea enclosure, characterized in that a) in an aqueous phase a solution containing water and optionally a surfactant, preferably 0.01-3, is prepared; 0% by weight, based on the aqueous phase,