MXPA00010630A - Encapsulated active materials - Google Patents

Abstract

The invention is an encapsulated active agent comprising an active agent encapsulated in a crystallizable or thermoplastic polymer wherein the particle size of the encapsulated active agent is 3,000 microns or less wherein the active agent is not significantly extractable from the particles under ambient conditions. In another embodiment the invention is a process for preparing an encapsulated agent which comprises:a) contacting an active agent with a crystallizable or thermoplastic polymer wherein the polymer is molten and the active agent is not volatile under the contacting conditions;b) forming particles of 3000 microns or less;and c) exposing the particles to conditions such that the portion of the particle at and near the surface undergoes rapid solidification. The encapsulated active agents of the invention do not require washing in order for them to be stable in curable compositions. These encapsulated active agents can be designed to release the active agent at a desired temperature. The encapsulated agents of the invention demonstrate excellent stability at ambient temperatures and exhibit relatively rapid reactivity upon release of the active agent. Furthermore, the presence of the encapsulating agent does not result in deterioration of adhesive or elastomer properties of a cured composition after preparation.

Description

ACTIVE ENCAPSULATED MATERIALS This patent application refers to encapsulated active materials, and preferably refers to encapsulated catalysts, accelerators and curing agents. In many cases the formulations that are useful as adhesives, sealants, coatings or in mixed applications, such as those based on a polysiloxane, an epoxy resin, a polyurethane, a vinyl ester resin, a polyester resin, an allylic resin, A polysulfide resin, a phenolic resin, an amine resin, require contact with a catalytic species, with accelerators or curing agents, in order to reach the final cure. This healing can begin at or slightly above room temperature, by immediate contact between the catalytic species, the accelerator or curing agent and the curable composition. Therefore, it is necessary to maintain the catalytic species, the accelerator or the curing agent and the curable composition, out of contact with each other, until the curing is desired. One approach commonly used is to formulate two-part compositions, in which the catalytic species, the accelerator or the curing agent are in one part, and the curable composition is elsewhere. The two-part compositions require packing as two separate portions, and may require additional capital for separate containment of the catalyst, accelerator or curing agent and curable material, together with mixing equipment for mixing the materials. Separate packaging and complicated equipment, such as dispensing and dispensing equipment, significantly increase the costs of such a system. Therefore, it is convenient to develop curable, single-part compositions that do not require packaging in two parts or complicated equipment to mix and apply. Hoffman and co-inventors, in US 5,601,761, describe a method for encapsulating an active material in a coating material immiscible with it, and having a melting point or transition point above room temperature. The method comprises dispersing the active material in the coating material at a temperature sufficient to melt the coating material; forming drops of active material interspersed with the coating material; cooling the drops to solidify the coating material to form particles; and contacting the particles with a solvent that dissolves the active material but does not dissolve the coating material, so that the active material is removed from the surface of the particles. The need to contact the particles with the solvent is the result of the fact that a significant amount of active material is contained on the surface of the particles formed or is extractable from the particles. This significant amount of active material, on the surface, or that is extractable, results in a lack of stability in single-part curable formulations. As a result, the inventors removed the active material from the surface by contacting the particles containing the active material with a solvent for the active material. This results in encapsulated, stable active material and stable compositions containing the encapsulated active material. The problem is that the washing of the particles after the formation results in a waste of active species, which is carried in the solvent and which increases the costs, due to the additional processing step, of washing the particles. Stewart and co-inventors, US Pat. No. 5,120,349, assigned to Landec Polymers discloses a process for encapsulating an active species, such as a herbicide, an insecticide, a fungicide or a fertilizer, in side chain crystallizable acrylate-based polymers. These encapsulated active species are prepared by dissolving or dispersing the active specs in a side-chain crystallizable acrylate polymer., hot, cooling the mixture and crystallizing the mixture. The formed particles are then ground. Bitler and co-inventors, WO 56/2641 describes the preparation of modifying agents, wherein the modifying agents comprise an active chemical portion, such as a catalyst or a curing agent, and a crystalline polymer portion, wherein the active chemical portion is chemically bound to the crystalline polymer portion. These are prepared as described in Stewart. It is described that these particles can be added to modify curable systems. They modify the curable systems when they are exposed to sufficient heat to melt the crystalline polymeric portion and, in that way, bring the active chemical portion into contact with the curable system. This system exhibits good stability, but the reactivity of this system is too slow for some applications. Bitler and co-inventors, WO 98/11166, describes modifying agents for curable systems, comprising crystalline polymers containing an active chemical ingredient, which is physically bound but not chemically bound to the polymeric ingredient. The active chemical portion and the system are similar to those described in WO 96/27641. Landec markets a product under the name Intelimer® 5012, which is dibutyltin dilaurate, encapsulated by a crystallisable, side-chain acrylate. The active species are located partially on the surface of the particle and / or are extractable from the particles. In some applications, the presence of the active species on the surface of the particle or the possibility of extraction of the active material from the particles results in instability of some of the formulations containing the encapsulated active species. In curable formulations this instability is exhibited by premature curing of the curable composition. This is indicated by a development in the viscosity of the composition. What is needed is an encapsulated agent that does not require extra processing steps after formation, such as washing, and is stable in a one-part formulation for extended periods of time, where the active species can be released on demand, by the application of some external phenomenon, such as pressure, shear force or heat. In other words, the system is stable at ambient temperatures, i.e., it does not undergo significant development of viscosity, cure indicator, and that cures rapidly once the system is exposed to conditions so as to release the encapsulated active agent, such as at the melting temperature of the encapsulated agent. In one embodiment the invention is an active agent encapsulated in the form of particles, comprising an active agent encapsulated in a crystallizable or thermoplastic polymer, where the particle size of the encapsulated active agent is 3,000 microns or less; where the active agent is not significantly extractable from the particles under ambient conditions during the first extraction after the particle preparation. In a preferred embodiment the encapsulated particle has a cover layer at and near the working surface to prevent release or removal of the active agent at ambient temperatures. Preferably, the cover layer contains substantially no active agent or such a low level of active agent that the stability of any formulation to which it is added is not detrimentally affected. In a preferred embodiment the particles of the invention have a cover layer at and near the particle surface and an inner portion of the particle surrounded by the cover layer, where the cover layer has a crystalline structure different from that of the crystalline structure of the inner portion, such that the active agent is not substantially extractable from the particles under ambient conditions during the first extraction after the particle formation. In a preferred embodiment the encapsulating agent is a crystallizable polymer; and it is more preferable that it be a side chain crystallizable polymer comprising a polymer or copolymer of an alkyl acrylate or alkyl methacrylate; where the polymer has substituted or unsubstituted side chains of 6 to 50 carbon atoms. In another embodiment, the thermoplastic or crisable polymer has a transition point of 40 ° C to 250 ° C. Preferably the active agent is not chemically bound to the encapsulating agent. In another embodiment the invention is a process for preparing an encapsulated agent comprising a) contacting an active agent with a crystallizable or thermoplastic polymer, wherein the polymer is melted and the active agent is not volatile or exhibits low volatility, under the conditions contact; b) form particles of 3,000 microns or less; c) and expose the particles to conditions such that the portion of the particle in and near the surface undergoes rapid solidification. In a preferred embodiment of the invention is a process for preparing an encapsulated active agent comprising heating a crystallizable or thermoplastic polymer, under such conditions, that the polymer melts; contacting an active agent with the molten polymer to disperse or dissolve the active agent within the polymer; pouring the active agent dispersed or dissolved in the polymer onto a rotary disk so that particles of the active agent are formed in the polymer, centrifuged from the disk and solidified; wherein the active agent is not volatilized under the conditions of the process and the active agent is not significantly extractable from the particles formed at ambient conditions during the first extraction after the formation of the particles. In another embodiment, the invention is the product prepared by the process described in this paragraph. In a preferred embodiment, the active agent is an encapsulated organometallic catalyst. The encapsulated active agents of the invention do not require washing or extraction in order to be stable in the curable compositions. These encapsulated active agents can be designed to release the active agent at a desired temperature. The encapsulated agents of the invention demonstrate excellent stability at ambient temperatures and exhibit relatively rapid reactivity when the active agent is released. Additionally, the presence of the encapsulating agent does not result in deterioration of the adhesive or elastomeric properties of a cured composition after preparation. The active agent can be any material that is reactive in an environment and that needs to be separated from the environment until it is desired that the active agent reacts in the environment.

Examples of active agents include: catalysts, accelerators, biologically active compound curing agents, such as drugs, herbicides, fertilizers or pesticides. It is preferred that the active agent is a catalyst, a curing agent, an accelerator or a mixture thereof. The active agent can be any material that dissolves in, or forms a heterogeneous suspension with, the encapsulating material at temperatures at which the encapsulating agent is in liquid form, ie melts. It is preferable that the active agent is soluble in the encapsulating material. The active agent may be a liquid or a solid at room temperature, but it is preferable that it be liquid at the processing temperature. The melting point of the active agent can be greater than, less than, or equal to, the melting point of the encapsulating material. It is preferable that the active agent is an organometallic or organic catalyst, a curing agent or an accelerator that does not volatilize or degrade under the temperatures of the encapsulation process. It is preferable that the active agent is a silanol condensation catalyst, a hydrosilylation catalyst, a catalyst, a curing agent, or an accelerator useful in the preparation of prepolymers or thermosetting resins such as polyurethane prepolymers or polyurethane compositions, epoxy resins, vinyl ester resins. polyester resins, ion resins, polysulfide resins, phenolic resins, amino resins. In a preferred embodiment, the active agent is an organometallic catalyst that is not volatilized or degraded under the conditions of encapsulation. Other catalytic species that may be useful are catalysts that promote moisture cure of polyurethane prepolymers. Catalysts useful in polyurethane reactions include: tin carboxylates, organosilicon titanates, alkyl titanates, tertiary amines, tin mercaptides, naphthenates or alkanoate salts of lead, cobalt, manganese, bismuth or iron. Useful catalysts for the formation of urethane are well known to those skilled in the art, and many examples can be found, for example, in the Poiyurethane Handbook, chapter 3, section 3.4.1, on pages 90-95; and the Poiyurethane Chemistry and Technology, in chapter IV, pages 129-217. Preferred tin compounds include the tin (II) salts of organic carboxylic acids, such as tin (II) diacetate, tin (II) dioctanoate, tin (II) diethylhexanoate and tin (II) dilaurate; dialkyltin (IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate; and stannous salts of carboxylic acids, such as stannous octoate, stannous oleate, stannous acetate and stannous laurate. Other catalysts useful in promoting the cure of polyurethanes include dimorpholinodialkyl ethers, N-alkylbenziamines, N-alkylmorpholines, aliphatic N-alkyl-polyamines, N-alkylpiperazines, triethylenediamine, amidines, such as 2,3-dimethyl-3,4, 5,6-tetrahydropyrimidine, tertiary amines, such as triethylamine, tributylamine, dimethylbenzylamine, N-methyl-, N-ethyl-, N-cyclohexylmorpholine, N, N, N ', N, N'-tetramethylethylenediamine, N, N, N' , N'-tetramethylbutanediamine, N, N, N ', N'-tetramethyl-1,6-hexanediamine, pentamethyl diethylenetriamine, tetramethyldiaminoethyl ether, bis (dimethylaminopropyl) urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo [3.3.0] octane and 1, 4 -diazabicyclo [2.2.2] octane. The active agents, useful in this invention, include the silanol condensation catalysts, which promote the reaction of the reactive silicon groups. Examples of silanol condensation catalysts are the titanic acid esters, such as tetrabutyl titanate, tetrapropyl titanate, etc .; organotin compounds, such as dibutyltin dilaurate, dibutyltin maleate, dibutyltin diacetate, tin octylate, tin naphthenate, dialkyl tin oxides, dialkyltin oxide reaction products, and esters of italic acid or alkanediones; dialkyltin bis (acetylacetonate) (also known as dialkyltin acetylacetonates); organoaluminum compounds, such as aluminum trisacetylacetate, aluminum trisethylacetate, diisopropoxyaluminium ethylacetate, etc .; reaction products of bismuth salts and organic carboxylic acids, such as bismuth tris (2-ethylhexoate), bismuth tris (neodecanoate), etc .; chelate compounds, such as zirconium tetraacetylacetonate, titanium tetraacetylacetonate, etc .; organoplyl compounds, such as lead octylate, organovanadium compounds, amine compounds, such as butylamine, octylamine, dibutylamine, monoethanolamine, diethanolamine, trnetanolamine, diethylenetriamine, triethylenetetramine, oleylamine, cyclohexylamine, benzylamine, diethylaminopropylamine, xylylenediamine, triethylenediamine, guanidine, diphenylguanidine, 2,4,6-tris (dimethylaminomethyl) phenol, morpholine, N-methylmorpholine, 2-ethyl-4-methylimidazole, 1,1-diazabicyclo (5.4.0) undecene-7 (DBU), etc .; or its salts with carboxylic acid, etc .; low molecular weight polyamide resins obtained from excess polyamines and polybasic acids; reaction products of excess polyamines and epoxy compounds, etc. These silanol catalysts can be used individually or in combinations of two or more. Among the silanol condensation catalysts, organometallic compounds or combinations of organometallic compounds and amine compounds are preferred from the point of view of ease of curing. Preferred silanol condensation catalysts are organometallic compounds. More preferred are organotin compounds, such as dibutyltin oxide, dibutyltin dilaurate, dibutyltin maleate, dibutyltin diacetate, tin octylate, tin naphthenate, dibutyltin oxide reaction products and italic acid esters, bis (acetylacetonate). of dibutyltin. In another embodiment the active agent can be a cure accelerator, for an epoxy resin composition. Said accelerator is preferably a urea or an imidazole. Preferred ureas include: 3-phenyl-1, 1-dimethylurean, 3- (4-chlorophenyl) -1, 1-dimethylurea, 3- (3,4-dichlorophenyl) -1 1 -dimethylurea, 1,1 '- (4-methyl-m-phenylene) bis (3,3'-dimethylurea), 3-isomethylimethylurea, 3,5,5-trimethylcyclohexyldimethylurea or 4,4'-methylenebis (phenyldimethylurea) The most preferred urea of all is 3- f eni I-1, 1-dimethylurea (PDMU). Preferred imidazoles include the alkyl- or arylimidazoles, such as 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-ethylimidazole, 2-isopropylimidazole and 2-phenyi-4-methylimidazole; 1-cyanoethyl derivatives, such as 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole and 1-cyanoethyl-2-isopropylimidazole; and carboxylic salts, such as 1-cyanoethyl-2-ethyl-4-methylimidazole trimellitate. Other catalysts for curing epoxy resin compositions, which may be useful as an active agent in this invention include those described in U.S. Patent 5,344,856, in their relevant portions. In another embodiment, the active agent can be a hydrosilylation catalyst. Said hydrosilylation catalysts are described in US patent 5,567,833, in column 17, lines 26 to 54; in U.S. Patent 5,409,995; in US Patent 3,971,751; and in US Patent 5,223,597. The most preferred hydrosilylation catalyst of all is chloroplatinic acid. In still another embodiment, the active agent may be an amine or an imidazole, which function as a catalyst, as a curing agent or as an accelerator in a polymer curing reaction. Amines primary, secondary and tertiary amines are included in the amines, as described herein.

In another additional embodiment, the active agent is a free radical catalyst or a free radical initiator. Free radical catalysts and free radical initiators are well known in the art; and their examples are described in US Patent 4,618,653 and US Patent 5,063,269, in column 6, lines 37 to 54. Preferably the active agent is an organometallic compound, more preferably, the active agent is an organotin compound. It is further preferred that the useful organotin compounds are dialkyltin oxides, such as dibutyltin oxide, dialkyltin bis (acetylacetonate) or the reaction product of dibutyltin oxide in an italic ester or pentanedione. In the embodiment in which the active agent is an active agent with an organic base, care must be taken to ensure that the organic active agent and the encapsulating agent are selected so that the organic active agent can be encapsulated within the encapsulating agent. a temperature at which the organic active agent is not volatilized. The use of an encapsulating agent in which the active agent is soluble reduces the volatility of the active agent and increases the formation of the desired particles. That it does not volatilize, means here that, under the conditions of the active agent particle formation, encapsulated, the formed particle does not exhibit substantial extraction of the active agent at ambient conditions, during the first extraction after the formation of the particle. It is preferred that the active agent has a low partial pressure, under the conditions of particle formation. The active agents exhibit increased solubility in the encapsulating agents having a polar nature such as, for example, polyesters, polyamides and crystalline side chain polymers. The encapsulating agent is a thermoplastic or crystallizable polymer having a transition point of 40 ° C to 250 ° C. The transition point, as used herein, refers to the point at which the thermoplastic or crystallizable polymer undergoes a change that results in the release of the active agent. A transition point is when the thermoplastic or crystallizable polymer melts and releases the active agent. Another transition point is when the thermoplastic or crystallizable polymer changes sufficiently to allow the active agent to come out by permeating the particles. It is preferable that the thermoplastic or crystallizable polymer portion must cross over the transition point, eg, a melt, on a relatively small temperature scale so that the release of the active agent can occur rapidly. It is preferable that the thermoplastic or crystallizable polymer has a transition point at a temperature of 40 ° C or more; more preferably 50 ° C or more, and most preferably, 60 ° C or more. It is preferred that said thermoplastic or crystallizable polymer has a transition point at 250 ° C or less; more preferable, 200 ° C or less and, most preferably, 110 ° C or less. Preferably the encapsulating agent mentioned is a crystalline polymer. Preferred thermoplastic polymers include styrenics, styrene-acrylonitriles, low molecular weight chlorinated polyethylenes; soluble cellulose, acrylic, such as those based on methyl methacrylate or cycloaliphatic acrylates. It is preferable that the crystalline polymer is a polyolefin, polyester, polyamide, phenoxy thermoplastic, polylactic acid, polyether, polyalkylene glycol or a crystallizable polymer, with side chain. More preferably, the crystallizable polymer is a polyethylene, polypropylene, polyether, polyethylene glycol, thermoplastic phenoxy, polylactic acid or side chain crystallizable polymer. It is still more preferable that the crystallizable polymers are polyethylene, polyethylene glycol or a side chain crystallizable polymer, with the most preferred of all side chain acrylate polymers. The crystallizable polymer can be derived from a single polymer or from a mixture of polymers, and the polymer can be a homopolymer or a copolymer of two or more comonomers, including random copolymers, graft copolymers, block copolymers and thermoplastic elastomers. It is preferable that at least part of the crystallizable polymer is derived from a crystallizable polymer, with side chain (SCC). The SCC polymer can be derived, for example, from one or more acrylic, methacrylic, olefinic, epoxy, vinyl, ester-containing, amide-containing or ether-containing monomers. The preferred polymer portions of SCC are described in detail below. However, the invention includes other crystalline polymers having the desired properties, said other polymers include, for example, polymers in which the crystallinity is the result exclusively or predominantly of the polymer backbone.; for example, polymers of alpha-olefins containing from 2 to 12 carbon atoms, preferably from 2 to 8 carbon atoms, for example, the polymers of monomers having the formula CH 2 = CHR, where R is hydrogen, methyl , propyl, butyl, pentyl, 4-methylpentyl, hexyl or heptyl, as well as other polymers such as polyesters, polyamides and polyalkylene oxides, for example, polyetherhydrofuran. The crystallinity is preferred, such that the DSC heat of fusion is at least 10 J / g, particularly at least 20 J / g. The steric nature of the polymer portion can also be significant in determining the availability of that active portion. The SCC polymer portions that can be used in this invention include the portions derived from known SCC polymers, for example, from polymers derived from one or more monomers, such as substituted and unsubstituted acrylates, methacrylates, fluoroacrylates, vinyl esters, acrylamides, methacrylamides, maleimides, alpha-olefins, ro-alkylstyrenes, alkyl vinyl ethers, alkylethylene oxides, alkylphosphazenes and amino acids; polyisocyanates, polyurethanes, polysilanes, polysiloxanes and polyethers; all these polymers contain crystallizable, long chain groups. Suitable SCC polymers are described, for example, in J. Poly. Sci., 60, 19 (1962); J. Poly. Sci. (Polymer Chemistry) 7, 3053 (1969), 9, 1835. 3349, 3351, 3367, 10 1657, 3347; 18 2197; 1_9 1871, J. Poly Sci. Polymer Physics Ed. 1_8 2197 (1980); J. Poly. Sci. Macromol. Rev., 8, 117 (1974); Macromolecules 12, 94 (1979); 1_3 12, 15, 18.2141, 19,611; JACS 75, 3326 (1953), 76; 6280; Polymer J., 17, 991 (1985) and Poly. Sci. USSR, 21, 241 (1979). The SCC polymer portions, which are preferably used in this invention, can be broadly defined as portions comprising repeating units of the general formula: - Y - I Cy where Y is an organic radical that is part of the polymer backbone and Cy comprises a crystallizable porc. The crystallizable portion may be connected directly to the polymer backbone or through a divalent organic or inorganic radical, for example, an ester, carbonyl, amide, hydrocarbon (eg, phenylene), amino or ether linkage; or by means of an ionic salt ligation (for example, a carboxyalkyl ammonium, sulfonium or phosphonium ion pair). The radical Cy can be aliphatic or aromatic, for example, alkyl of at least 10 carbon atoms. The SCC portion may contain two or more different repeating units of this general formula. The SCC may also contain other repeating units, but the amount of those other units, preferably, is such that the total weight of the crystallizable groups is at least equal to, for example, twice the weight of the remainder of the block. Preferred SCC portions comprise side chains which in total contain at least five times more carbon atoms than the backbone of the portion; particularly side chains comprising linear polymethylene portions containing from 12 to 50, especially from 14 to 22 carbon atoms, or linear, perfluorinated or substantially perfluorinated polymethylene portions, containing from 6 to 50 carbon atoms. Polymers containing said side chains can be prepared by polymerizing one or more corresponding linear aliphatic acrylates or methacrylates, or equivalent monomers, such as acrylamides or methacrylamides. Many such monomers are available commercially, either as individual monomers or as mixtures of monomers identified, for example, as C12A, C14A, C16A, C18A, C22A; a mixture of C18A, C20A and C22A; a mixture of C26A to C40A; Fluorinated C8A (AE800, from American Hoechst) and a mixture of fluorinated C8A, C10A and C12A (AE12 from American Hoechst). The polymers may also optionally contain units derived from one or more other comonomers, preferably selected from other alkyl, hydroxyalkyl, and alkoxyalkyl acrylates and methacrylates (e.g., glycid methacrylates); acrylamides and methacrylamides; acrylic and methacrylic acids; acrylamide, methacrylamide, maleic anhydride and comonomers containing amide groups. Said other comonomers are generally present in a total amount of less than 50 percent, in particular less than 35 percent, especially less than 25 percent; for example, from zero to 15 percent. They can be added to modify the transition point or other physical properties of the polymers. The transition point of a polymer containing said polymethylene side chains is influenced by the number of carbon atoms in the crystallizable side chains. For example, the homopolymers of C14A, C16A, C18A, C20A, C22A, C30A, C40A and C50A, respectively, which typically have melting points of 20, 36, 59, 60, 71, 76, 96 and 102 ° C, while that the homopolymers of the corresponding n-alkyl methacrylates typically have melting points of 10, 26, 39, 50, 62, 68, 91 and 95 ° C. The copolymers of said monomers generally have intermediate melting points. Copolymers with other monomers, for example, acrylic acid and butyl acrylate, typically have somewhat lower melting points. Other polymers that can provide SCC portions for use in this invention include atactic and isotactic polymers of n-alkyl-alpha-olefins (e.g., atactic and isotactic polymers of 16 carbon atoms, having Tm of 30 ° C and 60 ° C, respectively); n-alkyl-glycidyl ether polymers (for example, the alkylglycidyl ether polymer of 18 carbon atoms); n-alkylvinyl ether polymers (for example, the alkyl vinyl ether polymer of 18 carbon atoms having a Tm of 55 ° C; n-alkyl-alpha-epoxide polymers having a Tm of 60 ° C); n-alkyl-oxycarbonylamidoethyl methacrylate polymers (for example, the C18 IEMA polymers carbon atoms, 22 carbon atoms IEMA and 30 carbon atoms IEMA having Tm of 56 ° C, 75 ° C and 79 ° C, respectively); n-fluoroalkyl acrylate polymers (e.g., hexadecafluoroalkyl acrylate polymers of 8 carbon atoms, and a mixture of alkyl fluoroacrylates of 6 to 12 carbon atoms, having Tm of 74 ° C and 88 ° C, respectively); polymers of n-alkyloxazolines (for example, the alkoxazoline polymer of 16 carbon atoms, having a Tm of 155 ° C); polymers obtained by reacting a hydroxyalkyl acrylate or methacrylate with an alkyl isocyanate (for example, the polymers obtained by reacting hydroxyethyl acrylate with alkyl isocyanate of 18 carbon atoms or 22 carbon atoms, and having Tm of 78 ° C and 85 ° C, respectively); and polymers obtained by reacting a difunctional isocyanate; a hydroxyalkyl acrylate or methacrylate and a primary fatty alcohol (for example, the polymers obtained by reacting hexamethylene diisocyanate, 2-hydroxyethyl acrylate and alcohols of 18 carbon atoms or 22 carbon atoms, and having Tm of 103 ° C and 106 ° C, respectively). Preferred SCC polymer portions, used in the present invention comprise from 30 to 100 percent, preferably from 40 to 100 percent, of units derived from at least one monomer selected from the group consisting of alkyl acrylates, methacrylates of alkyl, N-alkyl acrylamides, N-alkyl-methacrylamides, alkyloxazolines, ethers to alkyl esters; alkylvinyl esters, alpha-olefins, alkyl-1,2-epoxides and alkylglycidyl ethers, wherein the alkyl groups are n-alkyl groups containing from 12 to 50 carbon atoms, and the corresponding fluoroalkyl monomers, in which the alkyl-alkyl groups are the n-fluoroalkyl groups containing from 6 to 50 carbon atoms; from 0 to 20 percent of units derived from at least one monomer selected from the group consisting of: alkyl acrylates, alkyl methacrylates, N-alkyl acrylamides, alkyl vinyl ethers and alkyl vinyl esters, in which the alkyl groups are n-groups alkyl containing from 4 to 12 carbon atoms; and from 0 to 15 percent units derived from at least one polar monomer, selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, vinyl acetate and N-vinyl pyrrolidone. Said SCC portions may also contain units derived from other monomers to change compatibility with the matrix, or to raise the modulus of a reaction product containing the modifying agent; said monomers include: styrene, vinyl acetate, functional monoacrylic polystyrene. It is preferable that the crystalline side chain polymers used do not contain a significant amount of functional groups, such as those having hydrogen atoms, since the presence of a significant amount of active hydrogen atoms increases the viscosity of the polymers and this may impact negatively the process used to prepare the encapsulated active agent particles. The number average molecular weight of the SCC polymer portion is preferably less than 200,000, more preferably, less than 100,000, in particular less than 50,000, more in particular, 1,000 to 20,000. The molecular weight of the SCC polymer portion can be adjusted (for example, by selecting the reaction conditions and the addition of chain transfer agents), in order to raise the reactivity of the fixed portions to the optimum point, without substantial changes in the Tm. The encapsulated active agent can be prepared by the following methods: a) dispersing or dissolving the active agent in the encapsulating material, at a temperature sufficient to melt the encapsulating material, but not so high as to volatilize the active agent; b) forming drops of active agent interdispersed with the encapsulating material; and c) cooling the drops to solidify the encapsulated material. Optionally, the process may further comprise step d) of contacting the drops with a solvent that dissolves the active agent, but does not dissolve the encapsulating material, in order to remove the active agent from the surface of the encapsulating material. It is preferred that this last step be avoided. This process is described in the patent US 5,601,761. More particularly, the encapsulating agent is heated until it is in a liquid state, ie, molten. Subsequently, the active agent is dispersed in the encapsulating agent. It is preferred that the active agent is not volatile under the conditions to which the encapsulating agent is melted. The mixture is formed into particles, preferably 3000 microns or less. Any means can be used to take a liquid composition or dispersion and form it into particles or droplets of the desired size, for example, atomization of the particles by any means, or dripping the liquid composition onto a rotating disk. Subsequently, the particles are exposed to conditions in which the surfaces of the particles solidify rapidly. Solidifying rapidly means that the active agent present in the formed particles can not be substantially extracted from the particles formed at ambient conditions, in a first extraction after the formation of the particles. Further evidence of rapid solidification is the formation of a shell or crust of the particle, where the encapsulating agent has a different crystal structure than in the inner portion of the particle. Generally fast solidification means that the particles solidify on the surface in a matter of seconds, preferably 10 seconds or less and, more preferably, 5 seconds or less. It is believed that exposing the particles to rapid cooling results in the desired structure and desired properties of the particles. Any means can be used to allow the particles to solidify rapidly on the surface. Passing the particles through an area of air or an inert gas, at room temperature, or by a cooled zone, is a method to rapidly solidify the surface of the particles. Any process that disperses the particles of the molten formulation in a cooling zone, such as an area with air, can be used. In carrying out this process the process temperature is selected in such a way that the encapsulating agent is in molten or liquid form and has a viscosity suitable for the processing technique used, such as a rotating disk. Additionally, the temperature and other process conditions must be selected in such a way that the active agent is not volatile. Generally, non-volatile or low volatility, as used herein, means that the active agent has a low partial pressure. Those who are experts in the field can easily determine the conditions and the appropriate components and the acceptable levels of volatility. At the preferred general temperatures at which the active agent is contacted with the encapsulating material it is 40 ° C or more; more preferable, 100 ° C or more; very preferable, 120 ° C or more and, preferably, 250 ° C or less; more preferably, 200 ° C or less and, most preferably, 180 ° C or less. A preferred process for the preparation of the particles is a process on a rotating disk. In a rotary disk process it is preferable that the prepared mixture has a viscosity that is suitable for use with the rotating disk. It is preferred that the viscosity of the material be 500 centipoise or less, more preferably, 100 centipoise or less and, most preferably, 50 centipoise or less. In order to obtain the desired viscosity for processing highly viscous polymers, it may be necessary to add a solvent or a plasticizer to the mixture. This is not preferred, since the presence of a solvent can result in increased costs and safety and environmental problems. In a preferred embodiment of this process, the active agent is dissolved in the molten polymer. It is believed that this provides better dispersion and distribution and that it reduces the volatility of the active agent. Preferably, the active agent is mixed with an encapsulating agent in the molten state at a temperature at which the active agent or a mixture thereof is not volatile. Under those circumstances, the prepared particle will not exhibit significant extraction of the active agent at ambient temperatures. This results in an encapsulated active agent, very stable, and a very stable adhesive formulation, prepared from said active agent. It is preferable that the temperature of the molten mixture that is poured onto the disk is at 75 ° C or more; more preferable, 100 ° C or more; and most preferably, 120 ° C or more, and it is preferred that it be 250 ° C or less, more preferably, 200 ° C or less and, most preferably, 180 ° C or less. Preferably the disk is rotating at 500 r.p.m. or more, more preferably, 1000 r.p.m. or more and, very preferably, 5,000 r.p.m. or more. The upper limit on the speed of rotation of the disk is the one that is practical. In a preferred embodiment the encapsulated active agent preferably exhibits a crystalline polymer scab, a polymer mixture having an active agent dispersed therein. The crystalline structure of this crust layer is different from the crystalline structure of the encapsulating agent, and of the crystalline structure inside the particle. Preferably there is not a significant amount of active agent in the crust, at and near the surface of the particle. It is believed that this crust layer at and near the surface prevents the extraction of the active agent by a solvent for the active agent. The presence of this layer is indicated by the active agent which is not extractable by a significant amount when the particles are contacted with a solvent for the active agent. The ability of the particle to resist extraction of the active agent, using a solvent, is an indication that the active agent erscapsulated is stable in a formulation at ambient temperatures, which means that significant amounts of the active agent will not come into contact with the curable composition and will initiate curing at ambient temperatures. In a preferred embodiment, it is believed that the encapsulated active agent of the present invention preferably has a crystalline polymer layer or crust, which has a crystal structure that is somewhat different from the polymer structure inside the particle . Preferably the active agent is not significantly extractable from the active agent particles in the encapsulating agent. By substantially non-extractable it is meant that there is no need to wash the surface of the particle with a solvent to make the particle stable in the adhesive formulation. Preferably not substantially extractable means that 10 percent or less of the active agent, based on the amount of active agent in the encapsulated active agent, is extracted by a solvent or plasticizer, when the particles are brought into contact with the solvent or with the plasticizer for the active agent; more preferable, five percent or less, and still more preferable, 1 percent or less; and more preferably still, 0.5 weight percent or less; and what is most preferred, 0.1 percent by weight or less. In some embodiments, the amount of active agent removed is below the detection limits of the analytical techniques used to measure the active agent, as demonstrated in Example 36 herein. The active agent, when released, can quickly activate or quickly initiate the healing reaction. It is preferred that the particles have a particle size of 3,000 microns or less, more preferably, 300 microns or less, still more preferable, 150 microns or less and, most preferably, 70 microns or less. It is preferable that the particles have a particle size of 10 microns or more, more preferably, 30 microns or more, and still more preferably, 50 microns or more. It is believed that a narrow particle size distribution improves the performance of the particles of the invention in the intended uses. It is preferable that the particles demonstrate a narrow distribution of particle sizes. A narrow or narrow particle size distribution means here that there is not a significant amount of particles with a size greater than five times the average particle size of the particles and, more preferably, twice the average particle size. As used herein, the particle size can be measured by means of particle size analysis by laser diffraction, as described in example 36. In a preferred embodiment the particles have a low aspect ratio, and it is even more preferable that they are spherical in shape. The concentration of active agent in the encapsulating agent particles is preferably 1 weight percent or more, more preferably 20 weight percent or more, and most preferably 25 weight percent or more. The concentration of the active agent in the particles of preference is 70 weight percent or less, more preferably 65 weight percent or less; still more preferable, 50 weight percent or less, and most preferably up to 45 weight percent or less, based on the total weight of the active agent and the encapsulating material. The encapsulated active agents of the present invention exhibit rapid activation times. An activation time means the time it takes for the healing reaction to begin, as exhibited by the onset of gelation. That time is measured from the time the composition is exposed to a medium to cause the encapsulating agent to release the active agent, such as a thermal source, until such time as noticeable gelling occurs. The encapsulated active agents exhibit activation times that approach the activation times of the non-encapsulated active agents. Thus, the encapsulation of the active agent does not significantly retard the activation of the curable composition. In a preferred embodiment, the formulation containing the encapsulated active agent begins to cure after it is exposed to activation conditions for ten minutes or less and, more preferably, five minutes or less and, most preferably, five minutes or less. The encapsulated active agents of the present invention can be used in any environment where there is a need for controlled release of the active material. The encapsulated agent can be mixed in a formulation of the reactive components and other adjuvants. To activate the reaction, the formulation is exposed to conditions that release the active agent. Said conditions may be the exposure to the necessary temperature, at which the encapsulating material is melted, or to which the active agent is allowed to penetrate through the encapsulating agent. Alternatively, the conditions could be shear stress, or exposure to ultrasonic waves, which causes the encapsulating material to release the active material. The encapsulated active agents of the present invention can be used in adhesive and coating formulations. The encapsulated active agents of the present invention demonstrate excellent stability in curable formulations. Formulations containing encapsulated active agents preferably demonstrate stability for more than three days, when exposed to environmental conditions (23 ° C and 50 percent relative humidity) and still more preferably, for five days or more. Stability means that the composition is not fully cured and, preferably, means that the composition has not undergone significant entanglement, as evidenced by the development of viscosity. The following examples were included for illustrative purposes only, and not to limit the scope of the claims. Unless stated otherwise, all parts and percentages are by weight.

EXAMPLE 1 800 g of a polyacrylate homopolymer of 22 carbon atoms (obtainable from Landec Corporation, Menlo Park, California) was heated to melt (mp> 70 ° C) and 200 g of Neostann® U-220, bis (acetylacetonate) dibutyltin. The tin catalyst was soluble in it. molten polymer and the solution was heated to 130 ° C. The tin catalyst solution was pumped into polyacrylate at a rate of 132 g / minute on the surface of a rotating disk which had been heated to 125 ° C and which was rotating at a speed of 15,000 rpm. The molten solution formed particular that were centrifuged into the ambient air in a collection space, for a period of 7 to 8 minutes. The particles settled to the ground and were collected in "butcher" paper. The final product was a yellow, powdery solid having particle sizes that were between 20 and 80 microns when observed under an optical microscope.

EXAMPLE 2 In the same manner as described in Example 1, 800 g of a copolymer of acrylate monomer, 22 carbon atoms and 1 percent acrylic acid was heated to melt (mp> 70 ° C) (obtainable from Landec Polymers, Menlo Park, California), lot No. 10011; and 200 g of Neostann® U-220, dibutyltin bis (acetylacetonate) was added. Again the tin catalyst was soluble in the molten polymer and the solution was heated to 155 ° C. The solution of tin catalyst in polyacrylate was pumped at a rate of 132 g / minute, on the surface of a rotating disk that had been heated to 159 ° C. The molten solution formed particles that were centrifuged into the ambient air in a collection space, for a period of 7 minutes. The particles formed sedimented to the floor and were collected in a butcher's paper. The final product was a powdery, dark colored solid, having particle sizes that were between 20 and 80 microns, when observed under an optical microscope. Encapsulated tin catalysts were formulated into model silicone formulations, vulcanizable at room temperature (VTA) and evaluated for stability and reactivity. Formulation 5.0 g of Kaneka S-303H, polyether based on methoxysilyl-terminated polypropylene oxide. 2.0 g of Palatinol 711 P, linear alkyl, mixed alkyl phthalate plasticizer. 0.175 g of Neostan U-220, tin catalyst prepared as described in Example 1. Comparative Formulation 1 5.0 g of Kaneka S-303H. Pelieter based on methoxysilyl-terminated polypropylene oxide. 2.0 g of Palatinol 711P, branched alkyl, mixed phthalate plasticizer. 0.035 g of Neostan U-220, tin catalyst (not encapsulated). At ambient temperature conditions, formulation 1 had 16-17 days of storage stability, without gelling. However, comparative formulation 1 gels in the term of hours. After storing for 17 days and heating formulation 1 for 2.5 minutes on a hot plate, regulated at 100 ° C, the curing starts and gelling occurs within hours (overnight).

EXAMPLES 3 TO 35 Several encapsulated active agents were prepared from various encapsulating agents and various catalytic materials. The catalytic materials of the encapsulating agents are mentioned in the list that follows. Table 1 lists the prepared encapsulated active materials, the charge level, the particle size and the processing temperature. The process for preparing the particles was as described in Example 1. Encapsulating materials (A). Poly (ethylene glycol), molecular weight 8,000 (B). Mixture of 95 weight percent methoxy-poly (ethylene glycol) of molecular weight 5,000 and 5 percent poly (ethylene oxide) of molecular weight 100,000. (C) Mixture of 98 weight percent methoxy-poly (ethylene glycol) of 5,000 molecular weight and 2 percent of Monamide S. (D). Mixture of 95 weight percent poly (ethylene glycol) of molecular weight 8,000 and 5% by weight of poly (ethylene oxide). (AND). Polywax 500, polyethylene wax. Crystallisable polyacrylate homopolymer, with 22 carbon atoms side chain, obtainable from Landec Polymers F.

Crystallisable polyacrylate with side chain of 22 carbon atoms, with acrylate groups containing 1 percent carboxyl. Catalysts: (A). Neostann® U-220, dibutyltin bis (acetylacetonate). (B) bis (dibutyltin 2-ethylhexanoate (C).) Dibutyltin oxide TABLE 1 EXAMPLE 36 AND COMPARATIVE EXAMPLES A AND B Three formulations were prepared for comparing the encapsulated catalysts of the invention with encapsulated catalysts prepared according to the disclosure of WO 98/11166. The model formulation 1 was used as the basis for the test. The samples were mixed manually until the resin and the plasticizer were homogeneous and the capsules were well dispersed. The encapsulating agent is a side-chain polyacrylate polymer with 22 atoms or rarbono, having a weight average molecular weight of 12,000 and an average number-average molecular weight of 7,000. The catalyst is dibutyltin acetylacetonate, sold under the trademark and trade name Neostann U-220, by Nitto Denko. The particles contained 80 weight percent encapsulating agent and 20 weight percent catalyst. The theoretical level of tin in the encapsulated tin particles was 5.5 weight percent. In Example 36, the encapsulated catalyst was prepared using the process that was described in example 1. In comparative example A the encapsulated catalyst was prepared using the process described in WO 98/11166, see examples 1 and 4. In the Comparative example B a spray drying process was used to prepare the encapsulated catalyst. Each of the samples was tested for tin level, particle size, reactivity, stability and the possibility of catalyst extraction. The following test procedures were used. The analysis of elemental tin was carried out by means of the neutron activation method. It irradiated samples and standards in a neutron field to create radioactive isotopes of the elements of interest. These radioactive isotopes are decomposed by the emission of gamma radiation, characteristic of the activated elements. In the case of tin, two isotopes emit gamma rays, with energies of 160 and 332 KeV. The half-lives of these two isotopes are 40.1 and 9.6 minutes, respectively. After a certain period of decomposition, the gamma radiation spectra of each of the samples and the standards are measured using high purity germanium detectors. After correcting for the decomposition of the radioactive isotopes, the peak areas of the gamma rays of interest (ie, 160 and 332 KeV) are compared with those of a norm of known concentration. The ratio of the peak areas is then used to calculate the concentration of the element of interest in the sample. Known quantities of each sample are charged in 7.39 ml polyethylene ampoules, dispersed in high purity graphite, and then sealed. Load known quantities in ampoules of 7.39 ml, dilute the standards to the appropriate volume with high purity water, and then seal the ampoules with the prepared standards. The samples and standards are then irradiated for ten minutes, at a power level of 10 kilowatts in a "Lazy Susan" installation of the nuclear reactor. After a 10-minute decomposition, their respective gamma radiation spectra are taken for 400 seconds, using two high-purity germanium detectors, using a multi-channel analyzer based on a computer. Tin concentrations are calculated using the Canberra * application program and common and current comparative techniques. The following nuclear reactions were used for the determination of tin in the catalyst samples: Sn (n, * r Sn; T1 / 2 = 40.1 minutes: * 'energy: 160 KeV; 124Sn (n, **) 152m Sn; T1 2 = 9.6 minutes; * energy: 332 KeV.

The particle sizes were determined using a Horiba LA 910 laser dispersion particle size analyzer. Samples were prepared by dispersing the capsules in Isopar G, with 0.1 percent of Aerosol OT 100. The samples were treated with sound to undo the agglomerates. The particle sizes of the samples were also analyzed, using a particle size analyzer, based on the darkening of light. The equipment included a Climet CI-1000 signal processor, and an RLV2-100EH sensor or an RLV5-250EH sensor. The samples were prepared taking approximately 0.15 g of material and placing them in a 25 ml ampule; 3 to 5 ml of 1% Triton X-100 in isopropanol was added to the dry powder to moisten the particles. Then the dispersion was treated with sound for approximately 30 seconds to undo any agglomerate. About 20 ml of water was then added to the dispersion, to further dilute it. The dispersion was passed through a sieve of 250 microns (60 mesh) to eliminate any large particles. Approximately 0.1 ml of the diluted dispersion passed through the sieve was added to approximately 225 ml of water; and this final dispersion was supplied to a particle size analyzer by light darkening; that is, a Climet CI-1000, equipped with a sensor. The precision of the measurements was evaluated by analyzing monodisperse samples of polystyrene spheres. For the reactivity studies, approximately 2 to 2.5 g of sample formulations are poured into a weighing tray of 1.4 g of aluminum. Activation of the capsules is achieved by placing the tray on a hot plate, heated at 100 ° C for 2.5 minutes. The sample is then stored in a laboratory bench, at ambient conditions, and its gelation is monitored. The time for a gel to form is recorded after activation. For stability studies about 2 to 2.5 g of samples of the formulations are poured into a weighing tray of 1.4 g of aluminum. The samples were placed in an oven regulated at 29 ° C. The time is recorded for a gel to form. The formulation for performing the extraction studies is ten parts by weight of capsules per 90 parts by weight of heptane. The capsules and heptane were added to an Erlenmeyer flask. The dispersion of the capsules was mixed, at room temperature, in a capped flask, equipped with a magnetic stirring bar, for thirty minutes. The sample was filtered in a Buchner funnel having a disc of Whatman No. 1 filter paper, dried and analyzed for tin. Table 2 shows the analysis of elemental tin for each of the samples.

TABLE 2 Table 3 tabulates the particle sizes of the capsules, as determined by a particle size analyzer, based on the darkening of the light, as described further back.

TABLE 3 Comparative experiment A (ground in air) and comparative experiment B (spray drying) had significant amounts of particles that were retained in a 250 mm sieve. In particular, samples from comparative experiment B had very large particles present. Example 36, prepared by the spinning disc method had a smaller particle size distribution than either of the other two samples. In general, the rotating disk sample has a much smaller fraction of particles larger than 250 microns in size. The particle size of the comparative encapsulated catalysts used was also determined using a Horiba LA 910 laser dispersion particle size analyzer, dispersing the powder in Isopar G with 0.1 Aerosol OT 100. The samples were treated with sound undo the agglomerated particles. The results are compiled in table 4.

TABLE 4 Table 5 shows a comparison of performance, in terms of both the reactivity and the stability of the encapsulated catalysts.

TABLE 5 * Gelification on hot plate A comparison of the results shows that the catalyst of example 36, prepared by the rotary disk process, clearly had better stability and better reactivity than any of the samples prepared by grinding in air (Comparative A) or drying by sprinkling (comparative B). Table 6 shows the results of the extraction studies.

TABLE 6 Heptane is a good solvent for the tin catalyst Neostann U-220; but poor solvent for the crystalline acrylate polymer, with side chain, Interlimer 8065. Thus, it is expected that washing the capsules with heptane remove the tin catalyst remaining on the surface of the capsule or extract the tin from the inside of the capsule . Based on this, a correlation between these test results and the stability of the formulations is expected. The best stability (> 21 days) is obtained with the sample example 36 (rotating disk) which also had the lowest level of tin lost. The results show that the capsule preparation according to example 36 (rotating disc) was superior to the preparation according to comparative examples A or B (air grinding or spray drying methods). The particle size distribution was more restricted, with a smaller fraction of particles of more than 250 microns for the sample of Example 36 (rotating disk). The reactivity was greater for the sample of Example 36 (rotating disk) obtaining the cure on hot plate, in this series of experiments. The sample of comparative example A (ground in air) had a reactivity that approximated that of the sample of example 36 (rotating disk). The sample of Comparative Example B (spray-dried) had a much lower reactivity. The stability of the sample of Example 36, prepared by the rotating disk, was better than that of the samples of Comparative Example A (ground in air) or Comparative Example B (spray dried). The sample of comparative example B (spray dried) had higher stability than the sample of comparative example A (ground in air) The combination of stability and reactivity was better for the sample of example 36 (rotating disk), exceeding the operation of the samples of comparative example A (ground in air) or of comparative example B (spray-dried), both in the reactivity studies and in the stability studies.The operation of both comparative samples indicates that the two processing techniques used for its preparation gives a compromise in the operation between stability and reactivity.This difference correlates with the particle size., the larger particles, prepared according to comparative example B (spray drying) have lower reactivity and greater stability than the particles prepared according to comparative example A (ground in air). There is a correlation between stability and removable tin catalyst. The very low levels of extractable tin obtained in example 36 (rotating disk) correlate with a much higher stability.

EXAMPLES 37 AND 38 AND COMPARATIVE EXAMPLES CAJ Formulations were prepared in accordance with formulation 2, with the three encapsulated catalysts as described in example 36 and in comparative examples A and B and with non-encapsulated dibutyltin bisacetylacetonate Neostan ™ U220, obtainable of Nitto. Formulation 2 consists of 100 parts by weight of Kaneka S-303H, polyether based on methoxysilyl-terminated polypropylene oxide, 40 parts by weight of a mixed alkyl phthalate plasticizer, Platinol ™ 711 P, and 3416 parts of encapsulated catalyst or 0.5 parts of non-encapsulated catalyst. In addition, the same four catalyst systems were tested in formulation 3. Formulation 3 comprises 99 parts by weight of Kaneka S-303H, a polyether based on methoxysilyl-terminated polypropylene oxide, 1 part by weight of water and 3 parts by weight of encapsulated catalyst or 0.6 parts by weight of unencapsulated catalyst. The formulations were tested according to the following procedures. 7 grams of the test formulations were heated on a hot plate, set at 100 ° C, for 2.5 minutes; and the time was recorded until the formulation gelled. The time was recorded and recorded so that the samples were free of stickiness. 7 grams of each formulation is exposed at 29 ° C, and the time until a gel is formed is recorded. The results are compiled in table 7.

TABLE 7 The formulations described in Table 6 were also subjected to the following tests. The time for the formulation to reach 50,000 centipoise was measured, using a Brookfield viscometer, model LVT, with spindle No. 4, at 25 ° C. During the short time periods, the samples were measured continuously, and during the longest times, the samples were tested by points. Ten gram samples were tested on aluminum trays for the gelation time at 25 ° C. The gel time was determined by the time the sample could be touched with a spatula and the spatula was dry. The time to be free of stickiness was the time when the sample no longer had a sticky surface, and had a dry superficial feel. It was determined that the cure time at 25 ° C was the time to reach 90 percent of the final properties of heat cure, as measured by the Shore A durometer. The results are compiled in Table 8.

TABLE 8

Claims (10)

1. CLAIMS 1. An encapsulated active agent, characterized in that it comprises an active agent dispersed in a crystallizable polymer; where the particle size of the encapsulated active agent is 3000 microns or less; wherein one percent or less of the active agent is extractable from the particles, when placed in contact with a solvent or plasticizer for the active agent, under ambient conditions, during a first extraction subsequent to particle formation; and the active agent is not volatilized under the conditions of particle formation.
2. 2. An encapsulated active agent according to claim 1, further characterized in that the 10 weight percent or less of the active agent, based on the weight of the active agent present in the particle, is extractable from the particles under environmental conditions , during a first extraction after the formation of particles.
3. 3. An encapsulated active agent according to claim 1 or 2, further characterized in that the particles have a crust layer at and near the surface of the particles.
4. 4. The encapsulated active agent according to any of claims 1 to 3, further characterized in that the crust layer does not contain a significant amount of «Active agent.
5. 5. An encapsulated active agent according to any of claims 1 to 4, further characterized in that the particles have a crust layer at and near the surface of the particle, and an internal portion of the particle, surrounded by the layer of crust, where the crust layer has a crystalline structure different from that of the crystalline structure of the inner portion.
6. 6. The encapsulated active agent according to any of claims 1 to 5, further characterized in that the crystalline polymer is a polyolefin, a polyester, a polylactic acid, a phenoxy thermoplastic, a polyamide or a side chain polymer. , crystallizable.
7. 7. The encapsulated active agent according to any of claims 1 to 6, further characterized in that the crystalline polymer is a crystallizable side chain polymer, comprising a polymer or a copolymer of an alkyl acrylate or an alkyl methacrylate. , wherein the polymer has substituted or unsubstituted side chains of 6 to 50 carbon atoms.
8. 8. The encapsulated active agent according to any of claims 1 to 7, further characterized in that the polymer or copolymer comprises a side chain alkyl acrylate of 22 carbon atoms.
9. 9. A process for preparing an encapsulated agent according to any of claims 1 to 8, characterized in that it comprises: a) contacting an active agent with a crystallizable polymer; wherein the polymer is melted and the active agent is non-volatile under the conditions of contact; b) forming particles of 3000 microns or less; and c) exposing the particles to conditions such that the portion of the particle at and near the surface undergoes rapid solidification, so that the particle formed has a different crystalline structure at and near the surface of the particle; wherein one percent by weight or less of the active agent is extractable from the particles formed when placed in contact with a solvent or plasticizer for the active agent, under ambient conditions, during a first extraction after the formation of the particle.
10. 10. A process for preparing an encapsulated active agent according to claim 9, further characterized in that it comprises: heating a thermoplastic polymer under conditions such that the polymer melts; contacting an active agent with the molten polymer to disperse or dissolve the active agent within the polymer; pouring the active agent dispersed or dissolved in the polymer onto a rotating disk, so that particles of the active agent are formed in the polymer, are centrifuged from the disk and solidify; where the active agent does not volatilize under the conditions of the process.