MXPA99009066A - Adherent microcapsules containing biologically active ingredients - Google Patents

Abstract

An aqueous suspension of microcapsules containing a biologically active material comprises an adhesive material in an amount effective to enable said microcapsules to adhere to an intended substrate.

Description

ADHERENT MICROCAPSULES CONTAINING BIOLOGICALLY ACTIVE INGREDIENTS FIELD OF THE INVENTION The present invention relates to suspensions of adherent capsules containing biologically active ingredients.

BACKGROUND OF THE INVENTION Various encapsulation materials are known, frequently, by means of interfacial polycondensation. For example, U.S. Patent No. 3,577,515 mentions capsules containing dyes, inks, chemical reagents, pharmaceuticals, flavoring materials, pesticides, herbicides, peroxides and, in fact, all that can be dissolved. , suspended or, otherwise, constituted in or as a liquid enclosed by the capsule. U.S. Patent No. 1,371,179 describes the preparation of polyurea capsules to contain dyes, inks, chemical reagents, pharmaceuticals, flavoring materials, fungicides, bactericides and pesticides such as herbicides and insecticides. U.S. Patent Nos. 4,046,741; 4,140,516; 4,417,916; REF .: 31321 4,563,212 and European Patent No. 611,253 refer to the encapsulation of various materials. Canadian Patent No. 1,044,134 relates to the encapsulation of insecticides, particularly pyrethroids. Canadian Patent No. 1,179,682 relates to the encapsulation of pheromones. A pending United States Patent Application (file number 53319 USA 6A), filed on the same date with the present application, also refers to the encapsulation of various materials, including biologically active materials such as pheromones. The aforementioned patents make use of different forms of interfacial polycondensation, in particular the formation of capsules having polyurea and / or polyurethane / polyurea layer walls. Said capsules made by different methods have a diameter range of approximately 1 micron and approximately 2 mm, but most of them fall within the lower limit of this range, ie, approximately 250 microns, or even 100 microns, and under 1 micron approximately.

SUMMARY OF THE INVENTION An aqueous suspension of microcapsules containing a biologically active material, said suspension additionally comprises an adhesive material in an amount effective to allow said microcapsules to adhere to the desired substrate.

DESCRIPTION OF THE PREFERRED MODALITIES For purposes of the present invention, the term "biologically active" refers to materials that affect the life processes of organisms. Materials that are biologically active include herbicides, pesticides, pharmaceuticals and semiochemicals, including naturally and artificially produced pheromones. Microcapsules containing such biologically active ingredients and which additionally contain an adhesive material that can be applied conveniently, by spraying. This is particularly advantageous in the fields of forestry, agriculture and horticulture, where aerial spraying is preferred as a means of application. The powdered capsules are applied to the foliage, to which a continuous contact is desired. For example, insecticides and vines should remain in the foliage if they are to have maximum effect. In the absence of the adhesive material described herein, the microcapsules can be blown or removed by washing the foliage by the action of wind and rain. It is necessary that any treatment that transforms the capsules into adhereptes does not do so at the expense of other valuable properties. For example, for spraying for use in forestry, agriculture or horticulture, ideally, the capsules are particles that will remain suspended in water, usually with a suspending agent. The adhesion properties imparted to the capsules should not result in the aggregation of the capsules together in the aqueous suspension. Said aggregation would, of course, render the capsules unsuitable for pulverization and would ruin the entire object of the capsules. Also, any material used to impart adhesion properties should not affect the integrity of the particles; nor should it dissolve or weaken the capsule layer. The compositions herein are aqueous suspensions, which provide a significant advantage in use. Other compositions that administer encapsulated insecticides and herbicides are solvent-based, which constitutes a significant disadvantage since said solutions release volatile organic compounds (VOCs) into the environment. For the purposes of the present invention, a volatile organic compound (VOC) is any volatile organic material that has a vapor pressure at 20 ° C higher than 0.1 Torr (mm Hg) that is not an active ingredient (e.g. insecticide, herbicides or other similar). More preferably, the Volatile Organic Compounds can be defined as those having a vapor pressure at 20 ° C higher than 0.02 Torr which is not an active ingredient. Because the aqueous suspensions of the present invention need not contain any appreciable amount of these undesirable VOCs, the composition is, in general, significantly more environmentally friendly. Preferred compositions of the present invention contain no more than 5% by weight of VOC and, more preferably, contain no more than 2% by weight of VOC. Jurisdictions such as Los Angeles, among others, that have a considerable environmental contamination problem will find in the present highly preferred aqueous suspensions due to their low environmental pollution effect.

While currently, adhesive materials are sometimes used in agriculture to help herbicides and insecticides to adhere to organic substrates, until now, latex has been used to a certain extent only with non-chemical products. encapsulated Surprisingly, it has been found that the incorporation of an adhesive with the microencapsulated biologically active materials results in a composition that can be sprayed with a conventional spray apparatus. Contrary to expectations, it has been found that the viscous microcapsules of the present composition do not agglomerate in the spray orifice or in the storage container. During application, the adhesive latex is associated with the microcapsules and, therefore, does not completely coat the surface of the target substrates. Because the adhesive is soluble or dispersible in water, the composition has a limited but effective lifespan on the target substrate before the water eventually removes the material from the substrate. The adhesive latex used in the present composition can be any suitable water dispersible adhesive available in the art. In agricultural activity, such latex compositions are often known as punches or propagators. The punches are used to help non-encapsulated agricultural chemical products adhere to plants. The propagators are used to help disperse agricultural chemicals that are not encapsulated in the application. The preferred adhesives are acrylate-based adhesives. A latex that is suitable is marketed by Rohm & Haas with the registered trademark Companion. Another is marketed by Deerpoint Industries under the trademark DPI S-100 (a patented puncher / propagator). Examples of such adhesives are polymers made from "soft" monomers, such as, for example, n-butylacrylate, isooctyl acrylate or the like or copolymers made from a soft component, such as, for example, isobutylene, n-butylacrylate , isooctyl acrylate, ethylhexylacrylate, or the like; and a polar monomer such as acrylic acid, acrylonitrile, acrylamide, methacrylic acid, methyl methacrylate or the like. Non-spherical polyacrylate adhesives are commercially available, for example, as the line of Rhoplex ™ adhesives from Rohm and Haas. Preferably, the non-spherical polyacrylate adhesive is present in an amount ranging from 10 to 35% by weight of the total suspension. Additionally, it has been surprisingly discovered that viscous adhesive microspheres can be used to adhere a biologically active material containing microcapsules onto a desired substrate. The viscous microspheres have sufficient adhesion properties to provide the desired adhesive bond, and there is no danger of completely coating the microcapsule and possibly of inhibiting the release characteristics of the capsule. Surprisingly, the combination of a biologically active material containing microcapsules and viscous microspheres can be applied without the need to modify the orifices of conventional sprayers with a minimum amount of blockage or blockage problems. Preferably, the adhesive material is an acrylate or methacrylate-based adhesive system comprising microspheres of an elastomeric copolymer, infusible, dispersible and solvent insoluble, and inherently viscous, as described in U.S. Patent No. 3,691,140. Alternatively, this adhesive composition may comprise elastomeric, hollow, polymeric, acrylate, infusible, inherently viscous, solvent insoluble, and solvent dispersible pressure sensitive adhesive microspheres, as described in U.S. Patent No. 5, 045,569. Other suitable adhesives are viscous microspheres that have hydrophilic, pendent polymeric or oligomeric moieties and are described in U.S. Patent No. 5,508,313. As an alternative, the adhesive comprises between about 60 and 100% by weight of elastomeric, hollow, polymeric, acrylate, infusible, inherently viscous, solvent insoluble and solvent dispersible pressure sensitive microspheres with a diameter of 20 to 100% by weight. at least 1 micrometer and, between 0% and approximately 40% by weight of a non-spherical polyacrylate adhesive. The hollow microspheres are made in accordance with what is mentioned in European Patent Application No. 371,635. Preferably, the biologically active materials are selected from pharmaceuticals, fungicides, bactericides and pesticides, such as herbicides and insecticides. Particularly preferred biologically active materials are pyrethroids, pheromones and other semiochemicals, whether naturally produced or artificially synthesized. The microcapsules may be any of the appropriate microcapsules for encapsulating biologically active materials, including polyurea, polyurethane, melamine / urea, gelatin microcapsules or the like. Microcapsules containing the biologically active material are preferably provided in a size in the range from 1 micron to 2 mm. Also, a method for preparing is provided. an aqueous suspension. of adherent microcapsules. Surprisingly, it has been found that careful mixing of the ingredients of the compositions of the present invention under basic conditions can be particularly beneficial to prevent the formation of a clot which would be impossible to apply using conventional spray equipment. The process comprises mixing A) an aqueous suspension of microcapsules having a pH either greater or less than 7, B) an aqueous suspension of adhesive having a pH either greater than or less than 7, such that the pH of A) and B) are both greater than 7 or less than 7. The adhesive suspension is selected from the group consisting of adherent microspheres, non-spherical aqueous latex adhesive or a combination of adherent microspheres and non-spherical aqueous latex adhesive . More preferably, the mixture takes place at a pH comprised between about 8 and about 9. Any base can be used to control the pH, for example an alkali metal or alkaline earth metal hydroxides or carbonates, however, the simplest and preferred one is the ammonia in an aqueous solution. Generally, the aqueous suspension A) of microcapsules of the present invention may contain between about 5 to 40 weight percent of microcapsules and, preferably, between about 5 to 25 weight percent of microcapsules before mixing them with the composition of adhesive. Typically, the aqueous suspension B) of the adhesive may contain between about 5 to 60 weight percent of the adhesive, and preferably between about 25 to 40 weight percent of the adhesive before mixing it with the microcapsule composition. Conveniently, between 10 and 30 parts by weight of the aqueous suspension of adhesive microspheres (composition B) is added to approximately 90 to 70 parts by weight of the aqueous microcapsule suspension. (composition A), to form a suspension of the invention. If a latex of non-spherical adhesive material is used, the amount again, conveniently, ranges from about 10 to about 30 parts by weight, which is added from about 90 to about 70 parts by weight of the microcapsule suspension. Slowly and carefully mix the aqueous suspension of the microcapsules and the aqueous suspension of the adhesive microspheres, or the latex-containing adhesive material, with agitation, in order to avoid rupture of the suspension. Conveniently, the mixing will be carried out at room temperature. As noted above, the compositions of the present invention are particularly suitable to be administered on a given substrate in a simple and inexpensive manner. Specifically, the compositions of the present invention are administered simply and effectively on organic substrates such as, for example, foliage, crops and weeds. The unique formulation allows microcapsules containing a biologically active ingredient to adhere to these organic materials without undue coating of the substrate and without unintentionally interfering with their life processes. Similarly, the compositions of the present invention can be easily applied to non-human skin and hair as well as to humans in need of treatment. Also, the compositions herein can be applied on non-organic substrates such as, for example, buildings, sidewalks, soil and the like in an effective and effective manner with excellent retention of the active ingredient in the desired substrate. Surprisingly, it has been found that an aqueous suspension of microcapsules and adhesive material in a given substrate can be economically applied by means of a spray device in the form of an aerosol. This method of application can be conveniently employed in the case of microcapsules containing any filler material but, in particular, it is convenient for microcapsules containing a biologically active material. In such cases, the desired substrate is preferably foliage, crops or weeds. More preferably, the adhesive material is an aqueous suspension of adhesive microspheres. Said microspheres surprisingly provide excellent adhesion to the desired substrate and do not coat the microcapsules or inhibit the release of the contents encapsulated therein.

As described in U.S. Patent Nos. 3,691,140; 5,045,569; and 5,508,313 and European Patent Application 371,365 as well as the aforementioned patent application (file of agent No. 53319 USA 6A) was incorporated herein by reference. The invention is illustrated in the examples presented below.

Example 1 An aqueous suspension of adhesive microspheres (20 g, as described in U.S. Patent No. 5,508,313, example 2 having an IOA: AA: Carbowax ratio of 97: 2: 1) was neutralized was neutralized with NH40H (8 g in 20 g of water). An aqueous suspension of microcapsules of a pheromone, E-11-tetradecen-1-yl acetate encapsulated in a polyurea layer (50 g) and a suspension agent of ramsan gum, were added with stirring. A good adherent microcapsule suspension was obtained. In a comparative test, adhesive microspheres (20 g as described above) were mixed with 20 g of water. An aqueous suspension of E-ll-tetradecen-1-yl acetate microcapsules was introduced into a polyurea layer (50 g) and a healthy gum suspension agent, with stirring. The components coagulated and, despite dilution with an additional 80 g of water, an unusable clot is obtained. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims (19)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. An aqueous suspension of microcapsules containing a biologically active material, characterized in that said suspension additionally comprises an adhesive material in an effective amount, to allow the microcapsules to adhere to a desired substrate, wherein the adhesive material is in the form of a aqueous suspension of adhesive microspheres.

2. A suspension according to claim 1, characterized in that the adhesive microspheres are elastomeric copolymer microspheres, based on acrylic or methacrylate infusible, solvent dispersible, insoluble in solvent and inherently viscous.

3. A suspension according to claim 1, characterized in that the adhesive microspheres are hollow.

4. A suspension according to claim 1, characterized in that the biologically active material is a pharmaceutical product.

5. A suspension according to claim 1, characterized in that the biologically active material is selected from the group consisting of fungicides and bactericides.

6. A suspension according to claim 1, characterized in that the biologically active material is a pesticide.

7. A suspension according to claim 1, characterized in that the biologically active material is selected from the group consisting of herbicides and insecticides.

8. A suspension according to claim 1, characterized in that the biologically active material is selected from the group consisting of pyrethroids and pheromones.

9. A suspension according to claim 1, characterized in that the microcapsules are composed of a biologically active material encapsulated in a layer that is selected from the group consisting of polyurea, polyurethane, mela ina / urea and gelatin.

10. A suspension according to claim 1, characterized in that the microcapsules are provided with a size in the range from 1 micron to 2 mm.

11. A process for preparing an aqueous suspension of microcapsules and adhesive microspheres, characterized in that the process comprises mixing an aqueous suspension A) of microcapsules containing a pH greater than about 7, with an aqueous suspension B) of adhesive microspheres having a pH greater than approximately 7.

12. A process according to claim 11, characterized in that aqueous ammonia is used to provide the pH greater than about 7.

13. A process according to claim 11, characterized in that the pH ranges between approximately 8 and 9.

14. A process for preparing an aqueous suspension of microcapsules and adhesive microspheres, characterized in that said method comprises the mixture of an aqueous suspension A) of microcapsules with a pH less than about 7, with an aqueous suspension B) of adhesive microspheres having a lower pH that approximately 7.

15. A process according to claim 11, characterized in that the aqueous suspension B) of adhesive microspheres containing from about 5 to 60 percent of the adhesive by weight after being mixed with the microcapsule composition A).

16. A process according to claim 11, characterized in that the aqueous suspension B) of the adhesive microspheres containing from about 25 to 40 percent of the adhesive by weight after mixing with the microcapsule suspension A).

17. A process according to claim 11, characterized in that approximately 10 to 30 parts by weight of aqueous suspension B) of adhesive microspheres is added to approximately 90 to 70 parts by weight of the aqueous suspension A) of microcapsules.

18. A method for applying microcapsules to a desired substrate, characterized in that it comprises a) preparing an aqueous suspension of microcapsules, wherein said suspension additionally comprises a suspension of adhesive microspheres in an amount effective to allow said microcapsules to adhere to a desired substrate, b ) releasing the suspension in a desired substrate through a spray device in the form of an aerosol.

19. The method, according to claim 18, characterized in that the desired substrate is selected from the group consisting of foliage, crops and weeds.