Abstract: A process for the preparation of an aqueous suspension of a solid free-radical forming initiator, a plant for the preparation, an initiator suspension and use of the suspension in polymerization of ethylenically unsaturated monomers. The process for the preparation of the suspension comprises the steps of:(a) heating the initiator to its melting point;(b) finely dividing the initiator in water while it is in a molten state;(c) rapid cooling so that the initiator is in a molten state for a period of time which is less than about 5 minutes.The initiator suspension has very small particles and a narrow particle size distribution whereby at least 50% by weight of the particles are smaller than 5 .mu.m and at least 90% by weight of the particles are smaller than 10 .mu.m.

Abstract: Silica particles which are substantially spherical, have a particle size of 1 to 100 .mu.m, a very narrow pore size distribution and a low alkali metal content. The particles can be prepared by sol-gel technique using emulsification technique for drop formation. The process comprises a sol growth step in a basic environment based on ammonium or amines and a post-treatment in such an environment. The silica particles are particularly suitable for use in chromatography as they have very good particle and porosity properties and high purity.

Abstract: Disclosed are amorphous silica or silica-alumina spherical particles composed of X-ray diffractometrically substantially amorphous silica or silica-alumina, wherein individual particles have a definite spherical shape and a notched surface, the circularity (A) represented by the following formula: ##EQU1## wherein r1 stands for the radius of the circumcircle of the profile of the particle in an electron microscope photo thereof and r2 stands for the radius of the inscribed circle of the profile of the particle in the electron microscope photo, is in the range of from 0.90 to 1, the notching degree (B) represented by the following formula: ##EQU2## wherein .DELTA.t stands for the depth between the peak and trough in the radial direction of notches on the profile of the particle in the electron microscope photo and r1 is as defined above, is in the range of from 1 to 10%, and the primary particle size (2r1) determined by the electron microscope method is in the range of from 0.1 to 20 .mu.m.

Abstract: Process for obtaining monodisperse microspheroidal particles, comprising spraying an electrostatically charged gellable liquid material through a spraying orifice and into a chamber, so as to produce macrodrops which break up into microdrops which fall in the chamber and within which gelling is produced after spraying. The microspheroidal particles thus obtained can be collected on a solid surface or preferably in a liquid medium and find application in the manufacture of silica-based microspheroidal particles. These microspheroidal particles can be employed as catalyst supports for alpha-olefin polymerization.

Abstract: A method is described for making hollow aerogel microspheres of 800-1200 .mu. diameter and 100-300 .mu. wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

Abstract: Silica microspheres formed by hydrolysis of a silica precursor having a mean diameter in the range of about 0.1 to 10 .mu.m are provided with a thin surface layer, often a monolayer, of a metal to provide the appearance of a solid particle of the metal as its oxide. The microspheres are contacted with an aqueous or alcoholic solution of a metal compound to deposit the surface layer.

Abstract: This invention relates to formed, polymeric complexes of metals of the eighth subgroup of the periodic system with ligands of an organosiloxane copolycondensate optionally cross-linked by means of cross-linking agents containing Si, Ti, Zr and/or Al, in the form of statistical, block or mixed copolycondensates. The ratio between the number of moles of phosphine units and the number of moles of bound metal atoms is 1:1 to 1000 to 1 and the ratio between the amine units and the phosphine is preferably 5:95 to 95:5 mole %. The polymeric complex compounds are present macroscopically as spherical particles with a diameter in the range of 0.01 to 3.0 mm, a BET surface of greater than 0 to 1000 m.sup.2 /g, a specific pore volume of 0.01 to 6.5 ml/g and a bulk density of 50 to 1000 g/l. The invention also includes several methods of preparing the complexes with post-treatment stages and the use of the polymeric metal complexes as catalysts in organic chemistry.

Abstract: The invention relates to a process in which a melt is mixed with, and emulsified in a colder aqueous phase at a temperature below the crystallization point of the molten compound, the melt only solidifying in the form of the dispersed particles after the emulsification step. To this end, the melt is sprayed into the aqueous phase to form a preliminary emulsion (12) and the preliminary emulsion is finely dispersed for 0.005 s to 0.15 s in a following homogenization nozzle (8) to form an emulsion (15) which then solidifies to form the final crystal suspension. The particle size can be clearly and reproducibly adjusted through the nozzle pressure during the emulsification step. The process may be used in particular for the production of highly concentrated dispersions of high-melting organic materials.

Abstract: A method for the production of inorganic oxide particles by a procedure comprising the steps of dispersing inorganic oxide particles as seed particles in a water-containing alcohol solution thereby preparing a suspension of said seed particles and adding a hydrolyzable and condensable organic metal compound to said suspension thereby effecting growth of said seed particles, which method further comprises causing the presence in said water-containing alcohol solution of an alkylene glycol having 2-8 carbon atoms, in an amount in the range of 1 to 50% by weight, based on the amount of said water-containing alcohol solution.

Abstract: A method to prepare spherical particles comprising magnesium oxide and magnesium hydroxide, wherein said magnesium hydroxide acts as a binder and no extraneous binder is present.

Abstract: Porous titania or zirconia spheres having a particle diameter of about 1 to 100 microns, a pore volume of about 0.1 to 1 cc/g, and a pore diameter in the range of about 10 to 5,000 Angstrom units are made by spray drying a slurry of ultimate titania or zirconia particles having a diameter about equal to that of the desired pore diameter of the formed sphere, and a reactive binder. The spheres can be used in high performance liquid chromatography columns and as catalyst supports.

Abstract: This invention relates to a composition, a method of preparing the composition and a catalyst using the composition. The composition consists essentially of a layered clay homogeneously dispersed in an inorganic oxide matrix. The clay is dispersed in such a way that the clay layers are completely surrounded by the inorganic oxide matrix. The inorganic oxide is selected from the group consisting of alumina, titania, silica, zirconia, P.sub.2 O.sub.5 and mixtures thereof. The clay can be a natural clay such as montmorillonite, a metal exchanged clay (Fe.sup.+3 exchanged) or a pillared clay such as aluminum chlorohydrate (ACH) pillared clay. The composition can be used as a catalyst for alkylation or hydrocracking or metals can be dispersed on it to provide a catalyst which is also useful for hydrocracking or alkylation.

Abstract: Hydrated sodium silicate particles can be expanded by heat to form thin-walled bubbles that can be broken, neutralized, washed and dried to provide hydrated silica flakes. These flakes can be mixed with non-swelling sorptive particles such as TLC grade silica and used to make chromatographic articles. One such article is a composite of a poly(tetrafluoroethylene) fibril matrix in which those particles and hydrated or fired silica flakes are enmeshed. The hydrated silica flakes can be fired to a refractory state and then incorporated into protective coatings to enhance their resistance to abrasion while also better protecting the coated substrates from corrosion.

Abstract: A process for producing a catalyst component for olefin polymerization is provided, which process comprises spraying a solution of a magnesium compound e.g. MgCl.sub.2 and an alcohol such as MgCl.sub.2. nROH (wherein R is 1-10 C alkyl and n is 3-6) into a cooled spray column to obtain a spherical solid component (carrier) without any substantial vaporization of the alcohol, followed by partly drying the component for a time till a specified ratio of the alcohol/MgCl.sub.2 is attained, and then subjecting the resulting component to treatment with a titanium halide and an electron-donating component, the resulting component having a large particle diameter, without any dispersion of the solvent content in the component particles and also without any breakage of the particles when subjected to treatment with the titanium halides.

Abstract: Disclosed is a process for drying aluminoxane, which comprises drying a viscous solution containing aluminoxane, while applying a shearing force sufficient to keep said viscous solution in polydispersive state, so as to make the solution to be a solid-state polydispersoid. Also disclosed is a process for producing a polymer which comprises polymerizing a polymerizable monomer, using the aluminoxane obtained by the process of the present invention.According to the process of the present invention, aluminoxane in uniform powder which is easy to treat can be efficiently obtained in an industrial scale, and polymers can be produced at high efficiency.

Abstract: A sol-gel method is employed to produce ceramic oxide spheres from precursors thereto. An alkanol of the sol precursor(s) is introduced to an immiscible hydrophilic liquid phase to cause spheroidizing of the sol. Moisture, which initially may be present in the immiscible liquid or may subsequently be added, is employed to effect hydrolysis of the precursor to oxide form. The ceramic oxide spheres are recovered from the liquid phase and calcined to their final form.

Abstract: A process for the preparation of a solid catalyst of the Ziegler-Natta type comprises precipitating the solid catalyst in a liquid hydrocarbon medium by reacting (A) a solution of a soluble magnesium alkoxide and (B) a transition metal halide which is a halide of Ti (IV), a halide of V (IV) or a halide of VO (III) in the presence of (C) at least one transition metal alkoxide which is free from halogen and soluble in liquid hydrocarbon. The precipitated solid catalyst consists of spheroidal particles having a mean diameter by mass of from 10 to 70 microns and a narrow particle size distribution such that the ratio of mean diameter by mass to the mean diameter by number is greater than 1.2 and smaller than 2.0.

Abstract: The invention involves a method for making uniformly sized particles from solid compounds. First, a suitable solid compound is dissolved in a suitable solvent. Then, a precipitating liquid is infused, precipitating non-aggregated particles with substantially uniform mean diameter. The particles are then separated from the solvent. Depending on the solid compound and the desired particle size, the parameters of temperature, ratio of non-solvent to solvent, infusion rate, stir rate, and volume can be varied according to the invention. The precipitating liquid may be aqueous or non-aqueous, depending upon the relative solubility of the compound and the desired suspending vehicle.

Abstract: Means and methods of producing catalytically coated microspheres of hydrocarbon fuel in a tower into which precharged free floating initially frozen globules of hydrocarbon fuel are drawn through a catalytic plasma field by an attracting electrostatic force disposed thereabove for catalytic coating and partial neutralization of the globule precharge until the coated globules descends in response to gravitational forces through the plasma field into a container disposed therebeneath.

Abstract: A process for producing highly uniform microspheres of silica having an average diameter of 0.1-10 .mu.m from the hydrolysis of a silica precursor, such as tetraalkoxysilanes, which is characterized by employing precursor solutions and feed rates which initially yield a two-phase reaction mixture.

Abstract: A finely divided aluminoxane comprising an aluminoxane represented by formula [I] or [II] ##STR1## wherein R denotes a hydrocarbon group having 1 to 10 carbon atoms and m denotes an integer of 2 to 50,an average particle size being 5 to 200 .mu.m and a specific an average particle size being 5 to 200 .mu.m and a specific surface area being 20 to 1000 m.sup.2 /g, a process for producing same, and a catalyst component for polymerization of olefins being said finely divided aluminoxane.

Abstract: Highly monodispersed nonporous spherical SiO.sub.2 particles are prepared having mean particle diameters between 0.05 and 10 .mu.m with a standard deviation of not more than 5% and a method for the preparation of such particles. The particles can be produced by a two step process wherein first a sol of primary particles is prepared by hydrolytic polycondensation of tetraalkoxysilanes in an aqueous/alcoholic ammoniacal medium. The SiO.sub.2 particles are then converted to the desired particle size by a continuous measured addition of tetraalkoxysilane or organotrialkoxysilane controlled by the extent of the reaction. The SiO.sub.2 particles produced by this process are particularly useful as sorption material in chromatography.

Abstract: This invention relates to the preparation of small spheroidal solid agglomerates. More particularly, the process produces strong solid spheroidal agglomerates containing alumina or a mixture of alumina and at least one other inorganic material, which process comprises:(a) mixing at high speed a portion of alumina or a mixture of alumina and at least one other inorganic material in the form of hydrophilic mircon-sized particles in a water-immiscible liquid thereby forming a dispersion;(b) gradually adding to the dispersion an aqueous acidic phase while continuing the high-speed mixing until substantially spherical micro-agglomerates form within the water-immiscible liquid;(c) subjecting the micro-agglomerates to agitation in a vessel having a hydrophobic inner surface at a speed low enough to achieve substantially uniformly sized spheroidal agglomerates;(d) drying the agglomerates to produce hardened spheroidal uniformly sized agglomerates; and(e) optionally further separating the agglomerates by size.

Abstract: Disclosed is a method of making a catalyst precursor by aging an aqueous solution containing the monoperoxovanadium ion, VO(O.sub.2).sup.+, until a vanadium-containing sol or gel is formed, and reacting said vanadium while in said aqueous sol or gel form, with an antimony compound that contains Sb having a valence of 3. In one embodiment, the VO(O.sub.2).sup.+ ion is made by reacting H.sub.2 O.sub.2 with a vanadium compound.Also disclosed is making a catalyst by drying and calcining such precursor. When the drying is effected by spray drying a microspheroidal catalyst is produced. The catalysts useful for ammoxidation of propane are more attrition resitant than catalysts of the same empirical formula made by prior art methods.

Abstract: A method for preparing silica gel particles, which comprises suspending a mixed solution of a silicic acid ester and water in an organic liquid immiscible with the mixed solution, followed by gelation wherein said organic liquid contains an ethyl cellulose having an ethoxy group content of at least 47% by weight and being soluble in the organic liquid.

Abstract: A process for producing a blend of maraging steel alloys and an oxidizable metal comprises forming an aqueous solution or iron, cobalt, nickel and molybdenum in a predetermined ratio. Thereafter, a reducible solid material containing the metals is produced from the solution. The solid material is reduced to metallic powder particles which are entrained in a carrier gas and fed into a high temperature zone to form droplets which are cooled to form essentially spherical shaped metal alloy particles. These particles are combined with a predetermined amount of at least one easily oxidizable metal selected from the group consisting of aluminum, titanium and vanadium to form a relative uniform blend of the spherical shaped particles and the readily oxidizable metal.

Abstract: A process for the manufacture of substantially spherical particles of at least one metal compound of Group II of the Periodic Table, comprising dissolving such compound in a solvent therefor to form a solution and introducing the solution into a non-solvent medium; said non-solvent medium consisting essentially of at least two liquids that are non-solvents for said compound, at least one of said non-solvents being immiscible with the solvent solution and at least one of said non-solvents being miscible with said solvent solution.

Abstract: Monosized ceramic particles produced through synergistic combination of monosized latex particles and organometallic reagents in a solvent system. By swelling a poly(vinyltoluene) or other monosized latex with an appropriate organometallic reagent, decomposing the organometallic to ceramic within the latex vehicle, and then removing the latex polymer through thermolysis, monosized ceramic particles are produced. The swelling of the monosized latex particles with the organometallic reagent requires the judicious selection of a solvent system specific to the latex polymer and organic being employed.

Abstract: Ultra-fine spherical particles of a metal oxide having an average particle diameter of 40 nm or smaller can be prepared by a method in which a vaporizable metal compound is vaporized and decomposed under heating to give ultra-fine particles of a metal oxide followed by immediate cooling down to a temperature at which coalescence of the fine particles are prevented from coalescence. The fine particles have characteristics such as an excellent power of ultraviolet scattering.

Abstract: Disclosed is a method of making a catalyst precursor by reacting the ion VO(O.sub.2).sup.+ in aqueous solution with an antimony compound that contains Sb having a valence of 3. In one embodiment, the VO(O.sub.2).sup.+ ion is made by reacting H.sub.2 O.sub.2 with a vanadium compound.Also disclosed is making a catalyst by drying and calcining such precursor. When the drying is effected by spray drying a new microspheroidal catalyst is produced. The catalysts useful for ammoxidation of propane are more attrition resistant than catalysts of the same empirical formula made by prior art methods.

Abstract: A composition of matter is prepared by a process comprising the steps of impregnating a alumina-containing support material with a thiosulfate (preferably ammonium thiosulfate), drying the thus impregnated material, impregnating the dried material with a transition metal compound, drying and calcining the transition metal impregnated material. This composition of matter is used as catalyst composition for hydrogenating unsaturated hydrocarbon compounds, and as catalyst composition for hydrotreating of hydrocarbon-containing feed streams (in particular heavy oils) which contain metal and sulfur compounds as impurities.

Abstract: A composition of matter is prepared by a process comprising the steps of impregnating a alumina-containing support material with a thiocyanate (preferably ammonium thiocyanate), drying the thus impregnated material, impregnating the dried material with a transition metal compound, drying and calcining the transition metal impregnated material. This composition of matter is used as catalyst composition for hydrotreating of hydrocarbon-containing feed streams (in particular heavy oils) which contain metal and sulfur compounds as impurities.In another embodiment, a hydrotreating process comprises contacting hydrocarbon-containing feed stream (in particular heavy oils), which contains compounds of sulfur and metals, in the presence of a fixed catalyst bed comprising (X) at least one layer of impregnated substantially spherical alumina-containing particles which have been prepared by a process comprising the steps of impregnating specific starting material with NH.sub.

Abstract: Highly monodispersed nonporous spherical SiO.sub.2 particles are prepared having mean particle diameters between 0.05 and 10 .mu.m with a standard deviation of not more than 5% and a method for the preparation of such particles. The particles can be produced by a two step process wherein first a sol of primary particles is prepared by hydrolytic polycondensation of tetraalkoxysilanes in an aqueous/alcoholic ammoniacal medium. The SiO.sub.2 particles are then converted to the desired particle size by a continuous measured addition of tetraalkoxysilane or organotrialkoxysilane controlled by the extent of the reaction. The SiO.sub.2 particles produced by this process are particularly useful as sorption material in chromatography.

Abstract: A hydrotreating process comprises contacting a substantially liquid hydrocarbon-containing feed stream, which contains compounds of sulfur and metals (preferably Ni and/or V), in the presence of a fixed catalyst bed comprising (a) at least one layer of impregnated substantially spherical alumina-containing particles which have been prepared by a process comprising the steps of impregnating specific starting material with (NH.sub.4).sub.2 SO.sub.4 and then heating the thus impregnated material at about 500.degree.-900.degree. C. for improved crush strength retention. In a preferred embodiment, the fixed catalyst bed further comprises at least one layer (b) of catalyst particles comprising a refractory inorganic carrier and at least one hydrogenation promoter. A composition of matter comprising the impregnated, spherical alumina-containing particles described above, and a process for preparing them are also provided.

Abstract: A process for the preparation of at least one porous oxide or hydroxide body comprises:(i) adding at least one body comprising a sol of the oxide or hydroxide to a fluid freezing medium; and(ii) raising the temperature of the solid, quenched sol so that solvent nucleation occurs, resulting in the formation of crystals of the dispersion medium, and the dispersion medium melts thereby leaving one or more porous oxide or hydroxide bodies.

Abstract: This invention relates to the preparation of small spheroidal solid agglomerates. More particularly, the process produces strong solid spheroidal agglomerates containing alumina or a mixture of alumina and at least one other inorganic material, which process comprises:(a) mixing at high speed a portion of alumina or a mixture of alumina and at least one other inorganic material in the form of hydrophilic micron-sized particles in a water-immiscible liquid thereby forming a dispersion;(b) gradually adding to the dispersion an aqueous acidic phase while continuing the high-speed mixing until substantially spherical micro-agglomerates form within the water-immiscible liquid;(c) subjecting the micro-agglomerates to agitation in a vessel having a hydrophobic inner surface at a speed low enough to achieve substantially uniformly sized spheroidal agglomerates;(d) drying the agglomerates to produce hardened spheroidal uniformly sized agglomerates; and(e) optionally further separating the agglomerates by size.

Abstract: Mechanically strong, H.sub.2 O-stable, macroporous spheroidal silica particulates, well adopted as catalysts/catalyst supports, are produced by (i) granulating and agglomerating a particular hydrosol of silica with a particular silica xerogel or aerogel, and (ii) drying the resultant silica particulates.

Abstract: The invention discloses a catalyst on the basis of silicon and titanium having the form of microspheres and constituted by oligomeric silica and by titanium-silicalite crystals having an oligomeric silica/titanium-silicalite molar ratio comprised within the range of from 0.05 to 0.11, wherein the crystals of titanium-silicalite are encaged by means of Si-O-Si bridges.

Abstract: This invention relates to highly attrition resistant catalysts, catalyst precursors and catalyst supports and to processes for making and using them.

Abstract: Metal halide particles useful, among other things, as olefin polymerization catalyst precursors and catalyst supports are prepared by vaporizing the metal halide and then condensing it in the presence of a diluent.

Abstract: Hollow porous microspheres are used as substrates and containers for catalyst to make microsphere catalysts.The hollow porous microspheres are made from dispersed particle compositions. The microspheres have a single central cavity, have substantially uniform diameters and substantially uniform wall thickness and the walls of the microspheres have substantially uniform void content, i.e., interconnecting voids, and have substantially uniform distribution of interconnecting voids. The interconnecting voids in the walls of the microspheres are continuous and extend from the outer wall surface of the microsphere to the inner wall surface of the microsphere.The microsphere catalysts are prepared by coating or impregnating the hollow porous microspheres with a catalyst or by applying a catalyst support to the microspheres and then coating or impregnating the microspheres and catalyst support with a catalyst.

Abstract: Uniform droplets of a bead-forming liquid are produced by positioning the end of a capillary tube in the throat of a venturi. An immiscible fluid flowing through the venturi detaches the droplets from the end of the capillary tube to produce uniform, spherical droplets which harden into spheroidal beads which have a uniform size.

Abstract: Substantially spherical solid particles of a substantially uniform particle size are prepared by dispersing a solution of a polymerizable substance in a first liquid by means of a suitble emulsifier to form droplets of the polymerizable substance of a substantially uniform particle size, which are thereafter poured into a second liquid with which the first liquid is immiscible and which contains a sufficient amount of a reactant to polymerize the polymerizable substance. After the polymerization the substantially spherical particles formed are recovered. In a preferred embodiment, an aqueous solution of an alkaline metal silicate, especially sodium silicate, is dispersed in a coparaffinate by means of a suitable emulsifier, and the emulsion is poured into an aqueous solution of the polymerization reactant to form gelled, substantially spherical hydrated silicate particles.

Abstract: This invention relates to the preparation of small substantially spherical solid catalysts. More particularly, the process produces strong solid substantially spherical agglomerates comprising inorganic materials, which process comprises:(a) mixing at high speed a portion of an inorganic material in the form of hydrophilic micron-sized particles in a water-immiscible liquid thereby forming a dispersion;(b) gradually adding to the dispersion an aqueous phase while containing the high speed mixing until substantially spherical microagglomerates form within the water-immiscible liquid;(c) subjecting the microagglomerates to agitation in a vessel having a hydrophobic inner surface at a speed low enough to achieve substantially uniformly sized spherical agglomerates;(d) drying the agglomerates to produce hardened substantially spherical uniformly sized agglomerates; and(e) optionally further separating the agglomerates by size.

Abstract: Microcapsules having a hydrophobic core material and capsule walls formed by the reaction of water-insoluble polyamines with water-soluble bisulphite adducts of polyisocyanates, a process for the production thereof which is characterized in that a mixture of a hydrophobic core material and water-insoluble polyamines is emulsified in water or in an aqueous protective colloid solution to the required particle size, water-soluble bisulphite adducts of polyisocyanates in the form of powders or aqueous solutions are added and the mixture is left to react to completion at temperatures of from 1.degree. to 140.degree. C., and applications thereof.

Abstract: A process for the formation of a spherical catalyst support comprising the steps of:(a) forming a mixture comprising:(i) 30-85 wt. % diatomite;(ii) 15-40 wt. % solvent;(iii) 0-15 wt. % fluxing agent; and(iv) 0-15 wt. % organic burnout material;(b) forming said mixture into generally spherical balls;(c) calcining said balls at a temperature in the range of about 700.degree. to 2300.degree. F. for about 10-45 minutes; and(d) thereafter, depositing at least one catalytically active substance on the surface of said spherical support in any suitable manner.The spherical support produced by the above process is especially useful as a support for immobilizing enzymes and microbial cells.

Abstract: Disclosed is an amorphous, spherical inorganic compound having a particle size of 0.1 to 1.0 .mu.m, which comprises as main constituents (1) an oxide of at least one metal selected from the group consisting of metals of the Groups I, II, III and IV of the Periodic Table, said metal oxide being capable of combining with silicon dioxide, and (2) silica.

Abstract: A catalyst which is a hollow microsphere comprising an outer shell in which there are feeder pores and an active ingredient arranged within the shell. The microsphere has a diameter ranging from 20 to 120 microns and the shell has a thickness ranging from 0.1 to 20.0 microns. The active ingredient fills 1.0% to 100% of the void space within the microsphere.

Abstract: For the preparation of spheroidal alumina, an alumina sol having a solids content of more than 20 to 40% by weight of alumina is prepared from alumina hydrate, which consists of boehmite/pseudo-boehmite, by thorough stirring in aqueous dilute acid, and the alumina sol is caused in the presence of 1 to 10% by weight of urea to drop into a forming column whose top portion is filled with a liquid hydrocarbon and whose bottom portion is filled with an aqueous solution of ammonia and which is held at room temperature, and the thus formed spheroidal particles are dried and activated. The resultant spheroidal particles may also be subjected to a per se known aging treatment.

Abstract: Microcapsules having a hydrophobic core material and capsule walls formed by the reaction of water-insoluble polyamines with water-soluble bisulphite adducts of polyisocyanates, a process for the production thereof which is characterized in that a mixture of a hydrophobic core material and water-insoluble polyamines is emulsified in water or in an aqueous protective colloid solution to the required particle size, water-soluble bisulphite adducts of polyisocyanates in the form of powders or aqueous solutions are added and the mixture is left to react to completion at temperatures of from 1.degree. to 140.degree. C., and applications thereof.