MXPA98004191A - Sol composition - Google Patents

Abstract

A microencapsulated and solid product is obtained by (1) preparing an aqueous film-forming medium comprising a film-forming polymer such as polyvinylpyrrolidone and an aqueous suspension of a microencapsulated material (ii) emptying the aqueous medium formed in this way on a substrate , and (iii) drying the drained medium to form a vacuum of the film-forming polymer containing the microencapsule material

Description

SOLID COMPOSITION DESCRIPTION OF THE INVENTION This invention relates to solid compositions and in particular to solid compositions dispersible in water containing microencapsulated materials, and to a process for their manufacture. Microencapsulation is a technique used in various industries that include, for example, the agrochemical industry. Generally the microencapsulation technique involves the formation of a dispersion or emulsion of a liquid relatively immiscible in water, in an aqueous medium to form an oil phase. The oil phase contains the material to be encapsulated, for example a liquid, an agrochemical substance immiscible with water, as well as one or more monomers which form a polymeric microcapsule wall surrounding the oil phase droplet when the polymerization, for example, by heating. A large number of variants of the microencapsulation process are known. Thus, for example, the water-immiscible liquid pesticide which forms the material to be encapsulated can be a solid agrochemical substance with a low melting point which is emulsified as a melt, or the liquid agrochemical substance immiscible in water can be a solution of a solid agrochemical substance in a solvent appropriate immiscible in water. As used herein, the term "microencapsulated material" means any material housed within a polymeric icrocapsule shell. As indicated above, the microencapsulated material is generally a relatively immiscible material in water and is formed as a suspension of the microcapsules in an aqueous phase. Microencapsulated materials have numerous advantages compared to a simple oil-in-water emulsion. For example, in the agrochemical industry, microencapsulated suspension formulations are used to reduce operator toxicity and exposure, compared to concentrated simple emulsion formulations. The microancapsulated suspension formulations are also used to provide controlled release of the agrochemical, the rate of release is determined, for example, by the thickness of the microcapsule wall, and by the nature of the polymer wall material. As indicated above, the microencapsulated formulations can be manufactured and used in the form of an aqueous suspension. For example, in agrochemical use, the suspension is usually diluted before use. However, there is a growing interest in the agrochemical industry for the use of solid rather than liquid formulations, since such formulations have the advantages in terms of reduced costs of transport, greater ease of handling and greater acceptability by the user. The contamination of the container is also greatly reduced by the use of a dry and solid formulation and therefore the disposal of the container is simplified. However, we have found that conventional methods for the conversion of liquid formulations into solid compositions, for example conventional granulation techniques, do not work with microencapsulated suspensions because the involved process tends to break the wall of the microcapsule and release the microencapsulated material. . Therefore, there is a need for a solid formulation of a microencapsulated material in which the microcapsules remain mainly intact, and which allows the regeneration of a suspension of microencapsulated material when the solid formulation is dissolved in water. It has now been found that such a product can be formed by emptying an aqueous film-forming medium containing the microencapsulated material. The casting of film-forming polymers, for example, "ribbon casting" to form polymer sheets is used in numerous industries and the techniques involved will be well known to those familiar with the art. In WO 93/23999 a packaging for storing and releasing incompatible materials for crop protection in which a chemical substance is "encapsulated" in a water soluble polymer film. However, the chemical protection of the crop, which may be in the form of a solid with a high melting point, a liquid, a wax, a granule or a powder, is simply added to a solution of the polymer in water and dried to form a suspension in the polymer film. Although the solid film containing the chemical for crop protection provides certain handling advantages, once it is redissolved in water, the chemical for crop protection is regenerated in the form of an aqueous solution, emulsion or dispersion and It does not have the advantages of a microencapsulated product. In addition, polymer films containing a chemical liquid for crop protection have poor handling and stability properties and it is only possible to incorporate relatively low levels of a liquid chemical substance for crop protection using this teque. According to the present invention there is provided a process for producing a solid and microencapsulated product which comprises: (i) preparing an aqueous film-forming medium comprising a film-forming polymer and an aqueous suspension of a microencapsulated material, (ii) emptying the aqueous medium formed in this manner on a substrate, and (iii) drying the void medium to form a void of the film-forming polymer containing the microencapsulated material.

The casting of the film-forming polymer containing the microencapsulated material is preferably removed from the substrate after drying to form a substantially dry "casting tape" comprising a microencapsulated material contained within a film-forming, water-soluble, casting polymer. Thus, according to a further aspect of the present invention, there is provided a solid and microencapsulated product, for example a microencapsulated agrochemical product, comprising a microencapsulated material contained within a film-forming polymer, water soluble, cast. The term "film-forming" polymer includes any polymer which is capable of providing film-forming properties in the presence of water. The film-forming polymer will generally be water soluble, but an aqueous film-forming medium may also be provided in which the film-forming polymer is present in the form of a dispersion, and in particular a colloidal dispersion or in the form of a solution. colloidal or in the form of a solution containing some dispersed material. The aqueous film-forming medium comprising an aqueous suspension of the microencapsulated material and the film-forming polymer can be prepared by incorporating the film-forming polymer during the microencapsulation process itself, or the film-forming polymer is it can be incorporated into a preformed aqueous suspension of a microencapsulated product. In general, the addition of all of the film-forming polymer such as a relatively viscous film-forming aqueous medium is present during the microencapsulation process itself and is likely to produce a medium with an undesirably high viscosity and consequently occur. encapsulation problems. Therefore, it is preferred to incorporate the film-forming polymer into a preformed aqueous suspension of the microencapsulated product, although of course, it would be possible to incorporate a proportion of the film-forming polymer during the encapsulation process and the rest of the film-forming polymer into the product. encapsulated formed in this way. The process of the present invention generally does not depend on the nature of the aqueous suspension of the microencapsulated material which is used as starting material and a wide range of such products can be used. Typical polymers which can be used to form the microcapsule may include polyurea and urea / formaldehyde resins. Typically, the polyureas can be reduced by condensation of one or more polyisocyanates or they can be produced by reaction between an organic polyisocyanate and an organic amine. Typically the urea / formaldehyde resins produced by autocondensation of etherified amino resins. Other types Known microcapsule wall polymers include polyamides, polyesters, polyurethanes and polycarbonates. The microencapsulated material may contain conventional adjuvants and additives such as surfactants. The process of the present invention is applicable in particular to the formation of a solid microencapsulated product containing a solid or liquid agrochemical product such as a herbicide, insecticide, fungicide, plant growth regulator, nematicide or an agrochemical adjuvant. However, the scope of the invention is not limited to agrochemicals, and can be applied to any suitable microencapsulated product. Suitable film-forming polymers include both synthetic and natural polymers such as polyvinylpyrrolidone, polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, modified polyvinylpyrrolidone such as a polyvinylpyrrolidone / vinyl acetate copolymer, polyethylene oxides, ethylene / maleic anhydride copolymer, copolymer of methylvinyl ether / maleic anhydride, water soluble cellulose such as carboxymethylcellulose, water soluble polyamides or polyesters, copolymers and homopolymers of acrylic acids, starches, natural gums such as alginates, dextrins and proteins such as gelatins and caseins. Mixtures of such film-forming polymers can also be used. The rate of dissolution of the product cast in water will depend on several factors, including in particular the nature of the film-forming polymer and the microencapsulated material. In some applications of the present invention it is desirable that the cast product dissolves rapidly when added to water. For example, if the drained product contains an agrochemical which is desired to be dissolved in a spray tank to form a suspended microencapsulated material, then a relatively rapid dissolution will be desired. In an alternative embodiment of the present invention, it may be desired to form a voided product which does not add to the water but releases the microencapsulated product slowly over a period of time, for example under the influence of moisture in the atmosphere or as a result of a slow diffusion of the active material through the microcapsule walls and from here through the solid polymer soluble in water. An example of this application, for example, is the formation of an emptied tape containing a public health product which is located in the home and slowly releases insecticide or other active material. We have found that polyvinylpyrrolidone is particularly suitable as a film-forming polymer which forms a voided product which dissolves and generally disperses rapidly in water, based on the other components of the cast product. The grades of commercially available, water-soluble or water-dispersible film-forming polyvinylpyrrolidone have molecular weights in the range from about 8,000 to more than 1,000,000 dalton units.

A preferred degree of polyvinylpyrrolidone has a molecular weight in the range of 30,000 to 360,000 and in particular from 40,000 to 60,000. Polyvinylpyrrolidones having a molecular weight of less than about 30,000 tend to form cast ribbons which dissolve relatively fast in water, but are relatively weak. Polyvinylpyrrolidones having a molecular weight greater than about 60,000 tend to form cast ribbons which are relatively strong but only dissolve slowly in water. We have found that good results are obtained using mixtures of film-forming polymers of different molecular weights. For example, a mixture of polyvinylpyrrolidone of high molecular weight, for example, a polyvinylpyrrolidone of molecular weight from about 40,000 to about 80,000 and a polyvinylpyrrolidone of relatively low molecular weight., for example, a polyvinylpyrrolidone of molecular weight from about 8,000 to 30,000 can be combined to provide excellent strength with relatively fast dissolution. It is considered that the relatively low molecular weight polyvinyl pyrrolidone can act as a disruptor to promote rapid disintegration of the tape structure upon contact with water without significantly sacrificing the strength of the tape when dry. Film forming polymers which form cast products which dissolve very quickly in water they may also have a tendency to absorb water from the atmosphere so that the surface becomes slightly sticky to the touch. It is possible to protect the surface, for example, by lamination as described in the following. Alternatively, a balance between an advantageous rate of dissolution and minimal adhesion can be reached by selecting the molecular weight of the polymer or by using a mixture of a rapidly dissolving polymer such as polyvinylpyrrolidone of molecular weight from 40,000 to 50,000, and a polymer that dissolves at least rapidly such as carboxymethylcellulose. Generally, there is no particular need for the cast product, for example the cast film, to show a particular strength since it must only have sufficient integrity to be handled before it dissolves. However, if the cast product of the invention such as the cast film is to be used as a container, for example as a water soluble bag container, it may be desirable to use a relatively strong polymer such as polyvinyl alcohol or polyvinyl acetate. partially hydrolyzed A sufficient amount of film-forming polymer must be used to form an aqueous film-forming medium, by which is meant an aqueous medium having an adequate rheology and in particular a viscosity suitable for casting into the substrate. If there is insufficient polymer in solution, the aqueous medium will tend to spill the substrate and form a film too thin. If, on the other hand, too much polymer is present in the aqueous medium, it will not flow smoothly, and the resulting film will not be self-leveling and uniform. The optimum concentration of polymer to provide an effective aqueous film-forming medium will vary based on the exact nature and degree of polymer used, but can be determined by simple and routine experimentation. Typical concentrations are illustrated in the examples. Thus, for example, the concentration of the film-forming polymer in the aqueous film-forming medium is typically from 5 to 95% by weight, for example from 5 to 50% by weight. The ratio of film-forming polymer to microencapsulated material in the aqueous film-forming medium, and therefore the portion of the film-forming polymer in the dried-out product may vary within wide limits, based on the specific application proposed. Sufficient film-forming polymer should be used to provide a dry, workable, flexible product. In general, if for example the cast product is a strip casting sheet, the ratio of the film-forming polymer to the microencapsulated material in the aqueous film-forming medium is from about 5 to 99% by weight, for example from about 10. up to 50% by weight, which results in a film-forming polymer ratio of about 0.1 to 95% by weight, for example, of about 5 to 50% by weight in the dry cast tape, based on the weights of any other component that may be present in the aqueous film-forming medium. The concentration of the microencapsulated material in the similarly cast product can vary within wide limits and typically ranges from 0.1 to 95% by weight. A typical aqueous microencapsulated suspension contains approximately 50% water and 50% solid material which generally provides a convenient ratio of water, so that the addition of sufficient film-forming polymer to form the aqueous film-forming medium provides an adequate ratio of film-forming polymer in the dry cast product. A more concentrated microencapsulated suspension will generally require less film-forming polymer relative to the microencapsulated material to provide an aqueous film-forming medium with the resultant that the ratio of film-forming polymer in the cast and dried product will be reduced. Inversely, a more dilute microencapsulated suspension will generally require more film-forming polymer relative to the microencapsulated material to provide an aqueous film-forming medium with the result that the proportion of film-forming polymer in the dry-emptied product will be increased. However, adjustments can also be made for microencapsulated suspensions diluted or concentrated by the addition of fillers, or the use of higher molecular weight or crosslinked polymers to provide optimum rheological properties for the aqueous film-forming medium. The film-forming polymer can be added to a suspension of aqueous microcapsules as a solid or a viscous aqueous concentrate. In any case, agitation will be required to ensure uniform mixing. The agitation should not be so vigorous that the walls of the microcapsules are broken, but we have found and even mixers with relatively high cuts can be used without problem for most conventional microencapsulated products. If aeration is considered disadvantageous during mixing, the vigor of mixing can be reduced or any antifoam can be added in the aqueous film-forming medium which can be placed to remove the air before use. However, we have found that aeration of an aqueous film-forming medium is not necessarily a disadvantage in that the aeration is carried out from the aqueous film-forming medium to the subsequent processing steps which can provide a partially dry drained product. foamed, with an improved dissolution rate. If desired, other components can be added to the aqueous film-forming medium. Thus, for example, it is desirable, particularly if the emptied product is going to be an emptied tape (or film) include a plasticizer to improve flexibility of the product emptied. Suitable plasticizers include glycerols, C2 to C6 glycols and polyglycols such as polyethylene glycol, dialkyl phthalates such as dioctyl phthalate, sorbitol and triethanolamine, or mixtures thereof. In addition to improving the flexibility of the product, a plasticizer can also have an advantageous effect on the rate of dispersion of the product emptied and dried in water. The proportion of plasticizer is preferably within the range of 0 to 80% by weight, for example, from 5 to 30% by weight relative to the film-forming polymer. Surfactants can be added to the aqueous film-forming medium both to improve the rate of dispersion of the dry cast product in water, and also to alter the surface tension properties of the aqueous film-forming medium in relation to the substrate on which it is to be emptied. Thus, for example, a humidifier may be added to ensure wetting of the substrate, for example if a plastic substrate is used. Surfactants can also be added which modify the surface tension of the wet cast film and ensure that, with drying, the film reduces its thickness with minimal shrinkage in the plane of the substrate on which it is emptied. A wide range of surfactants can be used for these purposes and suitable examples will occur to a person familiar with the art. Surfactants may be present with a relatively high charge in the product It can be used, for example, to provide adjuvant properties in the final application, for example, as a humidifier in a spray solution for agrochemical use. An antifoaming agent can be added to avoid excessive aeration during mixing of the film forming aqueous medium, although as indicated above, aeration of the aqueous film-forming medium is not necessarily a disadvantage. If desired, an inert filler may be added to provide a correspondingly charged dry drained product having properties normally associated with charged plastic products. Suitable fillers include organic or inorganic materials such as silica, mica, cellulosic fiber such as wood fiber, diatomaceous earth and urea. In general, the use of an inert charge will provide a low dry cost and easily worked tape. Tapes containing an inert charge will generally dissolve more slowly compared to a corresponding tape without such a charge. A viscosity aid can be added if you want to change the viscosity of the aqueous film-forming medium, for example, to minimize any sedimentation of the microencapsulated product within the thicknesses of the wet film when it is first emptied. Suitable viscosity modifying auxiliaries include alginates, starch, gelatins, natural gums, hydroxyethylcellulose, methylcellulose, silica and clays.

The emptying of the aqueous film-forming medium onto a substrate can take place using conventional techniques such as tape pouring. In tape casting, a film is formed on a substrate and the thickness is adjusted to that required using a device such as a "doctor blade" which defines a predetermined space between the surface of the substrate and the blade of the doctor blade. . The substrate is conveniently a flat and regular surface, but if desired, it may also possess indentations to provide the appropriate corresponding pattern on the surface of the film. Similarly, the "doctor blade" may have a contoured blade to provide a corresponding pattern on the upper surface of the film. At the end, the substrate may comprise one or more orifices in which the aqueous film-forming medium is emptied so that separate tablets or granules are formed on drying. It is a particular advantage of such tape casting techniques that the applied mechanical forces are relatively light so as to minimize any tendency for rupture of the microcapsules contained within the aqueous film-forming medium during processing. In general, any pouring technique can be used with the proviso that the mechanical forces involved are such that relatively few of the microcapsules are broken. In commercial practice, it is normal to supply the film-forming medium (in this case the film forming aqueous medium). containing the suspended microencapsulated material) from a reservoir and to form the film continuously, for example, by the use of a moving band as a substrate or by the movement of a reservoir and an associated doctor blade in relation to a stationary substrate. In commercial practice it is usually convenient to use a metal substrate, although plastic substrates can be used if desired. The pouring medium can be dried under atmospheric conditions, but more conveniently dried at elevated temperature. The upper limit of the drying temperature will depend on the nature and temperature sensitivity of the microencapsulated material. However, in general it is sufficient to dry the pouring medium at a temperature from the ambient to 100 ° C, for example from 40 to 60 ° C. It should be understood that the drying process does not necessarily eliminate all traces of water, but in fact there is a small proportion of residual water in the drained and dried product which can have a beneficial plasticizing effect. Typically, water levels are in the range between 0.1 and 20% by weight and are expected to be in a dry drained product. Heating may be obtained, for example, by passing the drained medium in an oven or heated space or by applying heat to the substrate. Once the drained medium is dried, it must be removed from the substrate for subsequent use.

The thickness of the emptied product can be varied, for example, of the cast belt within wide limits, according to the desired application. Typically, the thickness of a cast tape varies between about 0.04 mm and 5 mm, based on the flexibility and other desired characteristics. The dry tapes can be cut or shaped to include a wide variety of shapes and designs including, for example, disks, flakes, strips, tubes and spirals. The tape can be cut to provide a predetermined metered dose of active ingredient which simplifies the formation of a diluted agrochemical spray, for example. The tapes can also be engraved, corrugated or drawn with some pattern to increase the surface area and can also carry printed information such as product and safety information. For certain applications it may be desirable to protect the surface of the dried and emptied product. For example, it may be desirable to protect a layer of microcapsules located on or on the surface of a dry and emptied product, to prevent damage. Alternatively, it may be desired to use a film-forming polymer that is rapidly dispersed which provides some "tack" on the surface and which is adequately protected for some applications by a non-stick finish. The surface of the cast product can be easily protected by rolling or covacing with a layer of water soluble polymer which does not contain microencapsulated product and which may be the same as or different from the film-forming polymer. Alternatively, the dried and drained product can be housed in a water soluble bag which can be made of an equal or different water soluble polymer. The invention is illustrated in the following examples in which all parts and percentages are by weight unless stated otherwise.

EXAMPLE i This example illustrates the formation of a cast tape, based on the acetochloric herbicide, in the form of a microencapsulated suspension. Polyvinylpyrrolidone (1.5 g, molecular weight, 44,000), glycerol (0.15 g), surfactant (0.05 g, SYNPERONIC NP15-an ethoxylate of nonylphenol containing 15 moles of ethylene oxide per mole of nonylphenol) and antifoam (MSA, supplied) are added. by Dow Chemical) to 10 g of Acetochlor 40 CS (a suspension in a herbicidal cereal capsule containing about 36% by weight of acetochlor encapsulated in a polyurea wall in about 50% by weight of water). SYNPERONIC is a trademark of Imperial Chemical Industries. The mixture is stirred using a magnetic stirrer for a period of 15 to 30 minutes, until a viscous and homogeneous suspension. The rheology of the suspension under high shear conditions with as follows: Apparent viscosity (mPas, D 300S "1, 25 ° C) 512 Performance value (Pa, Casson) 0.373 The viscous film-forming medium is a ribbon cast on a polymer film (polyethylene terephthalate) as a substrate using a "doctor blade" placed at a knife height of 1 mm. The cast tape is dried for 15 to 20 minutes in an oven maintained at 50 ° C and then stretched from the substrate as a coherent tape. The cast strip product contains 74.0% microencapsulated acetochloric product (of which 72% is active ingredient), 22.3% polyvinylpyrrolidone, 2.2% glycerol, 0.7% surfactant and 0.7% antifoam. The tape has a thickness of 0.42 mm and shows excellent strength and flexibility. It rapidly disperses in water to form a microencapsulated suspension in which the microcapsule structure appears under microscopic examination which essentially does not seem to be affected. The dispersion time, measured by the standard test provided below, is 109 seconds. The time of dispersion of the tape is measured in a standard test by placing a piece of square tape that weighs 150 mg ± 2 mg in a mesh basket which is suspended below the surface of 500 ml of tap water (20 ° C ± 1 ° C) contained in a 600 ml glass beaker. The water is stirred at 400 rpm using a 5 cm (2 inch) stir bar. The time that is required for complete disintegration of the tape is noted.

EXAMPLES 2 TO 4 The procedure of Example 1 is repeated, except that the glycerol content of the formation is increased from 0. 15 g to 0.25 g and the polyvinylpyrrolidone is replaced as a film-forming polymer by 2.5 g of carboxymethylcellulose (example 2), by 2.5 g of AGRIMER VA6 (a vinyl acetate / vinylpyrrolidone copolymer, in a molar ratio of 60/40).

AGRIMER is a trademark of ISP (Great Britain) Co Ltd.

(Example 3) and by 2.5 g of AGRIMER AL 10 (an alkylated copolymer of polyvinylpyrrolidone with 10% butylation - (Example 4) In the case of carboxymethylcellulose, 5 g of water are added to obtain the correct properties of film formation of the film-forming medium and, in the case of AGRIMER AL 10., 2.5 g of water are added, in each case excellent tapes are added, the dispersion times measured by the standard method being 140 seconds (Example 2), 169 seconds (Example 3) and 158 seconds (Example 4).

The carboxymethylcellulose based tape has an excellent low surface adhesion.

EXAMPLE 5 The procedure of Example 1 is repeated using acetochlor 40 CS (20 g), glycerol plasticizer (0.3 g), SYNPERONIC NP15 (0.1 g) and antifoam (0.1 g) to which film-forming polymer consisting of a mixture of polyvinyl pyrrolidone is added. (2 g) and carboxymethylcellulose (1 g). Additional water (2 g) is added to provide the correct film-forming rheology. The resulting tape has strength and flexibility resistant and a relatively low adhesion.

EXAMPLE 6 The procedure of Example 5 is repeated using a film-forming polymer consisting of a mixture of polyvinylpyrrolidone (1.5 g) and carboxymethylcellulose (1.5 g). The resulting tape has excellent strength and flexibility and relatively low adhesion.

EXAMPLE 7 The procedure of Example 5 is repeated using a film-forming polymer consisting of polyvinylpyrrolidone (3 g) and a plasticizer consisting of polyethylene glycol of molecular weight 200 (0.3 g). The resulting tape has excellent strength and flexibility.

EXAMPLES 8 TO 11 The procedure of Example 1 is repeated using the weights of 40 SC acetochlor, polyvinyl pyrrolidone (molecular weight 40,000), glycerol plasticizer, surfactant (SYNPERONIC NP 15) and antifoam indicated in Table 1. No additional water is added. All the resulting tapes show excellent strength and flexibility.

TABLE l Weight of the components, in grams EXAMPLE 12 The procedure of Example 1 is repeated using acetochior 40 SC (20 g), polyvinyl pyrrolidone (3 g), glycerol (0.3 g), anti-foam MSA and MORWET powder D425 (0.05 g) (a solid surfactant consisting of the sodium salt of alkylated naphthalenesulfonic acid). The resulting tape has good strength and flexibility, and relatively little adhesion. The tape is dispersed in 10 177 seconds, measured using the standard method.

EXAMPLE 13 The general procedure of Example 1 is repeated using the same weights of polyvinylpyrrolidone (molecular weight 44,000), glycerol, surfactant, antifoam and acetochlor 40 SC, except that 0.75 mg of mica charge is added.

(Micro-Mica Wl, Norwegian Tale Ltd) during polymer blending. The suspension is emptied with a blade height of 11.3 mm. The resulting tape is 0.56 mm thick, strong and flexible, with a low surface adhesion and dispersed in 244 seconds, measured using the standard method.

EXAMPLE 14 The mixing / dispersion properties of the acetochloride ribbon produced according to Example 1 were determined using a 100 liter ALLMAN sprinkler. The tank is filled with 50 liters with water (temperature, 11 ° C). 136 g of the tape is added to the tank, the water is recirculated / agitated at an operating pressure of 4 bar. Subsequently, the tank is filled up to 100 liters and the spray is started. Spray samples are examined when the water level in the tank is 100, 75, 50, 25 and 3 liters. There is no blockage of the nozzle during spraying, the spray samples examined are essentially uniform in color and there is no tape residue present at the base of the tank when the spray is finished.

EXAMPLE 15 Polyvinylpyrrolidone (molecular weight 44,000, - 3 g), glycerol (0.3 g), SYNPERONIC NP15 (0.1 g) and MSA antifoam (0.1 g) are added to 20 g of ICON 10 CS, an insecticide in suspension in capsules containing approximately 10 g. % by weight of active ingredient, lambda cialotrin, encapsulated in a polyurea wall in about 70% by weight of water. ICON is a trademark of Zeneca Limited. The mixture is stirred using a magnetic stirrer for a period of 15-30 minutes until a viscous and homogeneous suspension is obtained.

The viscous film-forming suspension is drained in ribbon form on a polymer film as a substrate, using a "doctor's blade" that fits a blade height of 1 mm. The cast strip is dried for 15-20 minutes in an oven that is obtained at 50 ° C and then stretched from the substrate as a coherent tape. The tape drained product contains 62% microencapsulated ICON product (of which approximately 32% is active ingredient), 32% polyvinylpyrrolidone, 3.3% glycerol, 11.1% surfactant and 1.1% antifoam. The tape has a thickness of 0.34 mm and has excellent strength and flexibility. When dispersed in water to form a microencapsulated suspension, the microcapsule structure appears under microscopic examination essentially unaltered. The dispersion time of the tape is 346 seconds, measured using the standard method.

EXAMPLE 16 Polyvinylpyrrolidones (molecular weight 44,000, - 5 g) glycerol (0.5 g), SYNPERONIC NP15 (0.1 g) and MSA antifoam (0.1 g) are added to 20 g of ODRAM CS (a herbicidal suspension in capsules containing approximately 48% by weight of active ingredient, molinate, encapsulated in an aminoplast wall in approximately 50% by weight of water). ODRAM is a trademark of Zeneca Inc. The mixture is stirred using a magnetic stirrer during a period of 15-30 minutes aasta that obtains a viscous and homogeneous suspension. The viscous film-forming suspension is emptied in ribbon form on a polymer film as a substrate, using a "doctor's blade" which is adjusted to a blade height of 1 mm. The cast tape is dried for 15-20 minutes in an oven obtained at 50 ° C and then separated from the substrate as a coherent tape. The tape-emptied product contains 74% of microencapsulated ODRAM product 10 (of which approximately 96% is active ingredient), 22% polyvinylpyrrolidone, 3.7% glycerol, 0.4% surfactant and 0.4% foaming agent. The tape is 0.58 mm thick and has excellent strength and flexibility. The tape is not dispersed when immersed in water at 15-20 ° C for 30 minutes and is suitable for use as a non-dispersing tape for slow release of: active ingredient.

EXAMPLE 17 Polyvinylpyrrolidones are added (molecular weight 44,000 - 5 g), glycerol (0.5 g), SYNPERONIC NP15 (0.1 g) and antisugar MSA (0.1 g) at 20 g of FUSILADE CS a herbicidal suspension in capsules containing approximately 48% by weight of active ingredient, fluazifop-P- Butyl, encapsulated in a polyurea wall (15% wall material) in approximately 40% by weight of water.

FUSILADE is a trademark of Zeneca Limited. The mixture is stirred using a magnetic stirrer for a period of 15-30 minutes until a viscous and homogeneous suspension is obtained. The viscous film-forming suspension is tape emptied onto a polymer film as a substrate, using a "doctor blade" which is placed at a blade height of 1 mm. The cast tape is dried for 15-20 minutes in an oven maintained at 50 ° C and then released from the substrate as a coherent tape. The product empty of tape contains 62% of product FUSILADE microencapsulation (of which approximately 89% is an active ingredient), 34% polyvinylpyrrolidone, 3.4% glycerol, 0.7% surfactant and 0.7% antifoam. The tape is 0.76 mm thick and has excellent strength and flexibility. The tape is dispersed in water to form a microencapsulated suspension in which the microcapsule structure appears under microscopic examination essentially unaffected. The dispersion time of the tape is 636 seconds measured by the standard method.

EXAMPLE 18 A mixture of polyvinylpyrrolidone polymers of molecular weights 8000 (5.8 g) and 57,000 (2.8 g) is added to 38.5 g of KARAT? 25 SC (a suspension insecticide in microcapsules containing about 23% by weight of lambda-cyhalothrin encapsulated in a polyurea wall in about 50% by weight of water and agitated using a mechanical stirrer until all the polymer is dissolved. KARATE is a trademark of Zeneca Limited. Morwet EFW (an anionic naphthalene sulfate wetting agent from Witco, 0.2 g), sorbitol (2.5 g) and silicone antifoam (0.15 g) are added, and stirred for an additional 15 minutes to ensure complete dispersion. The resulting viscous film-forming suspension is stripped onto strips on a polymer film as a substrate using a "doctor blade" placed at a blade height of 1.2 mm. The cast tape is dried for 2 hours in an oven maintained at 50 ° C and then separated from the substrate as a coherent tape. Dry tape contains -3% microencapsulated KARATE product (of which approximately 46% is the active ingredient lambda cyhalothrin), 28% polyvinylpyrrolidone polymers, 0.6% surfactant, 8% sorbital and 0.4% antifoam. The tape is 0.52 mm thick. When dispersed in water to form a microencapsulated suspension, the walls of the capsule appear under microscopic examination essentially unaffected. The dispersion time of the tape is 420 seconds when measured using the standard method.

EXAMPLE 19 A blend of polyvinylpyrrolidone polymers of molecular weights 8,000 (5.8 g) and 57,0000 (2.8 g) are added to 31.5 KARATE 25 CS formulation and agitated using a mechanical stirrer until all the polymer is dissolved. Morwet EFW (0.2 g) and 7.0 g of Microtalc filler (hydrated magnesium silicate with an average particle size of about 7 μm) are added and stirred until all the powder is completely dispersed. Finally sorbitol (2.5 g) and silicone antifoam (0.15 g) are mixed and stirred for an additional 15 minutes to ensure complete dispersion. The viscous film-forming suspension is tape emptied onto a polymer film as a substrate, using a "doctor blade" placed at a blade height of 1.2 mm. The cast tape is dried for 2 hours in an oven maintained at 50 ° C and then separated from the substrate as a coherent tape. The dry tape contains 47% microencapsulated KARATE product (of which approximately 46% is the active ingredient lambda cyhalothrin), 25% polyvinylpyrrolidone polymers, 0.6% surfactant, 20% Microtalc filler, 7% sorbital and 0.4% antifoaming The tape is 0.53 mm thick. When dispersed in water to form a microencapsulated suspension, the walls of the capsule appear under examination microscopic essentially without alterations. The dispersion time of the tape is 620 seconds when measured using the standard method. EXAMPLE 20 The herbicidal efficiency of the drained tape of Example 1 is compared against the microencapsulated formulation from which the cast tape has been prepared. The cast tape of Example 1 and the corresponding microencapsulated formation are dispersed in water to provide concentrated solutions which are diluted and applied to weed species, woolly heather, broadleaf signal grass, shattercane, giant foxtail, white wild millet , horsetail, large crabgrass and red root amaranth. The two formulations are each applied at a rate of 10, 20, 40, 80 and 160 g / ha of the active ingredient and no significant herbicidal differences are detected between the tape casting formulation of the present invention and the microencapsulated product dispersed in corresponding liquid. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (12)

REVINDICACIQNES

1. A process for producing a microencapsulated, solid product, characterized in that it comprises: (i) preparing an aqueous film-forming medium comprising a film-forming polymer and an aqueous suspension of a microencapsulated material, (ii) emptying the aqueous medium formed therefrom; on a substrate, and (iii) drying the void medium to form a void of the film-forming polymer containing the microencapsulated material.

2. The process according to claim 1, characterized in that the film-forming polymer is polyvinylpyrrolidone, polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, a copolymer of polyvinylpyrrolidone / vinyl acetate, polyethylene oxides, ethylene / maleic anhydride copolymer, copolymer of methylvinyl ether / maleic anhydride, water soluble cellulose, polyamide or water soluble polyesters, a copolymer of acrylic acid homopolymers, starch, a natural gum or a protein or a mixture of two or more thereof.

3. The process according to claim 2, characterized in that the film-forming polymer comprises polyvinylpyrrolidone having a molecular weight in the range of 30,000 to 360,000.

4. The process according to any of the preceding claims, characterized in that the film-forming polymer comprises a mixture of a polyvinylpyrrolidone of molecular weight from 40,000 to 80,000 and a polyvinylpyrrolidone of molecular weight from 8,000 to 30,000.

5. The process according to any of claims 1 to 3, characterized in that the film-forming polymer comprises a polyvinylpyrrolidone of molecular weight from 40,000 to 50,000 and carboxymethylcellulose.

6. The process according to any of the preceding claims, characterized in that the concentration of the film-forming polymer in the aqueous film-forming medium is between 5 and 50% by weight.

7. The process according to any of the preceding claims, characterized in that the plasticizer is present in the film-forming medium.

8. The method according to any of the preceding claims, characterized in that the surfactant, the viscosity auxiliary and the antifoam or an inert filler are present in the film-forming medium.

9. The process according to any of the preceding claims, characterized in that the emptying means is dried at a temperature from 40 ° C to 60 ° C.

10. The process according to any of the preceding claims, characterized in that the surface of the cast product is protected by lamination or is emptied together with a layer of water soluble polymer which does not contain microencapsulated product.

11. A solid microencapsulated product, characterized in that it is prepared in any way by a method according to any of the preceding claims.

12. A microencapsulated, solid product, characterized in that it comprises a microencapsulated material contained within a film-forming polymer, soluble in water, drained. A microencapsulated and solid product is obtained by (i) preparing an aqueous film-forming medium comprising a film-forming polymer such as polyvinylpyrrolidone and an aqueous suspension of a microencapsulated material (ii) emptying the aqueous medium formed in this way on a substrate , and (iii) drying the voided medium to form a void of the film-forming polymer containing the microencapsulated material.