Abstract: A stabilised aqueous dispersion of particulate zinc oxide comprises water, a stabilising agent and zinc oxide, the particles of which are coated with dense amorphous silica. Useful stabilising agents include cellulose ethers which contain quaternary ammonium groups and polyalkylene glycols. The dispersions have excellent stability at high concentrations of zinc oxide and are useful for preparing sunscreen formulations, cosmetics and veterinary products.

Abstract: A process for the preparation of an ester comprises carrying out an esterification in the presence of a catalyst comprising the reaction product of an orthoester or a condensed orthoester of titanium or zirconium, an alcohol containing at least two hydroxyl groups, a 2-hydroxy acid and a base. The process can be a direct esterification or a transesterification and can be a polyesterification. The catalyst can effectively produce esters without leading to a haze in the final product and there is a reduced amount of yellowing of polyesters in comparison to known catalysts.

Abstract: A printing ink for radiation curing, e.g. by UV radiation or an electron beam, comprises a mixture of a polymerizable composition, a pigment or a dye and a titanium or zirconium compound which is an alkoxide of an unsaturated alcohol, said polymerizable composition comprising at least one unsaturated monomer and, optionally, at least one prepolymer and being polymerizable by exposure to radiation. The titanium or zirconium compound acts as an adhesion promoter for the ink.

Abstract: A process for preparing a composition suitable for topical application to human skin is disclosed. The process comprises mixing particles of metallic oxide dispersed in oil and having a primary particle size less than 0.2 micrometer with one or more emulsifiers, an aqueous phase and a hydrophilic organic sunscreen so as to prepare an emulsion. The composition contains up to 10 percent by weight metallic oxide and up to 7 percent by weight hydrophilic organic sunscreen. The emulsions are useful as sunscreen compositions, skin protectants, moisturisers, and after-sun lotions. The measured Sun Protection Factor for a composition of the invention is considerably higher than would be expected from a knowledge of the individual UV absorbing characteristics of the metallic oxide and the hydrophilic organic sunscreen.

Abstract: A method of curing a powder coating composition comprises reacting a polyester resin with an alkanolamine derivative of titanium or zirconium. This derivative is the reaction product of an orthoester or a condensed orthoester of titanium or zirconium with a trialkanolamine and with a dialkanolamine or a monoalkanolamine. In the reaction product the ratio of trialkanolamino radicals to Ti or Zr atoms is from 0.5:1 to 1.5:1 and the ratio of monoalkanolamino radicals or dialkanolamino radicals to Ti or Zr atoms is from 0.2:1 to 2.0:1. The reaction products are preferably derivatives of ethanolamines or isopropanolamines and can be used to cure carboxyl-rich resins or hydroxyl-rich resins.

Abstract: A printing ink comprises a polymeric binder, a solvent and an adhesion promoting agent which is the reaction product of a zirconium orthoester and ethyl acetoacetate in which the molar ratio of zirconium to ethyl acetoacetate is from 1:1 to 1:4. Preferably, the inks are based on nitrocellulose or an ester type modified cellulose. The inks have been found to have adhesion and heat stability properties similar to inks containing titanium acetylacetonate but the zirconium additives have a much reduced tendency to discolor the ink.

Abstract: A method of preparing sunscreens in which a dispersion of zinc oxide particles in an oil is formed by milling in the presence of a particulate grinding medium and mixed with cosmetically acceptable materials is claimed. The particles of zinc oxide have an average size of from 0.005 to 0.15 micron and the dispersion is substantially transparent to visible light but with an extinction coefficient at 308 nm (E(308)) and at 360 nm (E(360)) of at least 9 liters per gram per centimeter. The ratio E(360):E(308) is in the range 0.75:1 to 1.5:1.In a preferred method a mixed dispersion containing titanium dioxide and zinc oxide, having E(308) at least 15 liters per gram per centimeter, E(360) at least 10 liters per gram per centimeter and the ratio E(360):E(308) in the range 0.3:1 to 1.5:1 is used. The mixed dispersion is also claimed.The sunscreens prepared have a good balance of absorption for UVA and UVB radiation and better SPF values than those prepared from titanium dioxide and/or zinc oxide powders.

Abstract: The invention concerns a process for producing a water-in-oil emulsion comprising mixing an oil dispersion of particles of a metallic oxide having a primary particle size less than 0.2 micron with one or more emulsifiers and an aqueous phase.The method enables the production of such emulsions containing relatively small quantities of emulsifiers and a novel emulsion made available by the invention contains less than 1% by weight of emulsifiers, 10 to 60% by weight of an oil phase and at least 40% by weight of an aqueous phase.The emulsions so formed are useful in preparing UV absorbing compositions such as sunscreens, skin protectants, moisturisers and after-sun lotions.

Abstract: Process for producing a layered ceramic product which includes sintering layers of sinterable particulate ceramic material while in face-to-face contact. Before such contact, the surface of at least one of the layers is modified to provide a zone of weakness between the layers. This zone acts to deflect a crack propagating across the layers thereby increasing the work required to break the product. The product may also have improved fracture toughness.

Abstract: A method of preparing sunscreens in which a dispersion of zinc oxide particles in an oil is formed by milling in the presence of a particulate grinding medium and mixed with cosmetically acceptable materials is claimed. The particles of zinc oxide have an average size of from 0.005 to 0.15 micron and the dispersion is substantially transparent to visible light but with an extinction coefficient at 308 nm (E(308)) and at 360 nm (E(360)) of at least 9 liters per gram per centimeter. The ratio E(360):E(308) is in the range 0.75:1 to 1.5:1. In a preferred method a mixed dispersion containing titanium dioxide and zinc oxide, having E(308) at least 15 liters per gram per centimeter, E(360) at least 10 liters per gram per centimeter and the ratio E(360):E(308) in the range 0.3:1 to 1.5:1 is used. The mixed dispersion is also claimed. The sunscreens prepared have a good balance of absorption for UVA and UVB radiation and better SPF values than those prepared from titanium dioxide and/or zinc oxide powders.

Abstract: A composite particulate pigmentary material is disclosed which comprises an association of at least two chemically distinct materials in which the particles of one material carry a positive surface charge and the particles of the second material carry a negative surface charge and particles are held in association as a result of these surface charges. Also disclosed is a method for preparing composite particulate pigmentary material comprising forming aqueous dispersions of two particulate materials under conditions in which the surface charges of the particles of the two materials are of different signs and mixing the dispersions. Typical materials useful for preparing the composite include inorganic pigments, fillers and extenders and organic polymeric microspheres. The product is useful as a pigment in, for example, paints, inks, paper and plastics.

Abstract: The invention concerns a process for producing a water-in-oil emulsion comprising mixing an oil dispersion of particles of a metallic oxide having a primary particle size less than 0.2 micron with one or more emulsifiers and an aqueous phase.The method enables the production of such emulsions containing relatively small quantities of emulsifiers and a novel emulsion made available by the invention contains less than 1% by weight of emulsifiers, 10 to 60% by weight of an oil phase and at least 40% by weight of an aqueous phase.The emulsions so formed are useful in preparing UV absorbing compositions such as sunscreens, skin protectants, moisturizers and after-sun lotions.

Abstract: A method of preparing a mixture of zirconia and a stabilising agent for the zirconia comprises milling an aqueous suspension of particulate zirconia and particulate stabilising agent in a bead mill for at least 2 minutes in the presence of a particulate mixing medium having an average particle size from 0.2 mm to 3 mm. Preferred stabilising agents are oxides of yttrium, cerium, calcium or magnesium. Surprisingly, ceramics prepared from the product mixture are more resistant to degradation by attack from water above 100.degree. C. than are ceramics prepared from coprecipitated powders.

Abstract: An oil-in-water emulsion containing 0.5% to 30% metallic oxides having a particle size of less than 0.2 micron, less than 10% total emulsifier, 5% to 30% of an oil phase and at least 60% of an aqueous phase is provided. The invention also makes available a method of preparing such emulsions in which the emulsion is formed by use of a dispersion in water of the metallic oxide particles. By comparison with previously known emulsions of this type relatively small quantities of emulsifiers are used and it is possible to use an emulsion system with a low HLB value (e.g. less than 6). Preferably no hydrophilic emulsifiers are used. The emulsions are suitable for preparing UV-absorbing compositions such as sunscreens, moisturisers and after-sun lotions. The ability to use no, or little, hydrophilic emulsifiers is advantageous since, in, general, these emulsifiers are not biodegradable whereas hydrophobic emulsifiers generally are biodegradable.

Abstract: A process for the production of substantially crystalline silicon nitride comprising heating a mixture of ammonia and a silicon halide by means of an electric plasma formed in a stream of a non-oxidizing gas is described. Energy is transferred to the stream of gas at a rate of at least 30 kilowatts per mole of silicon halide per minute and at least 25 kilowatts. In a preferred embodiment gaseous material is caused to recirculate within the reactor so that there is a recirculation ratio (RR) greater than 2.5 where RR is defined by ##EQU1## wherein M.sub.n =mass flow of gas stream through the inlet nozzle, R=internal radius of the reactor into which said gas stream flows, M=mass flow of gases in the reactor at a distance 4R downstream from the inlet nozzle, R.sub.n =radius of inlet nozzle, D.sub.n =density of gas stream passing through the inlet nozzle, D=density of gases in reactor at a distance 4R downstream from the inlet nozzle.

Abstract: A novel process for preparing titanium dioxide from a titanium chloride consists of heating an aqueous solution of the titanium chloride in the presence of a salt of a polycarboxylic acid. The process is useful for producing titanium dioxide having a particle size between 0.1 and 1 micrometer and a purity which is suitable for more demanding electroceramic applications.

Abstract: An oil-in-water emulsion containing 0.5% to 30% metallic oxides having a particle size of less than 0.2 micron, less than 10% total emulsifier, 5% to 30% of an oil phase and at least 60% of an aqueous phase is provided.The invention also makes available a method of preparing such emulsions in which the emulsion is formed by use of a dispersion in water of the metallic oxide particles.By comparison with previously known emulsions of this type relatively small quantities of emulsifiers are used and it is possible to use an emulsion system with a low HLB value (e.g. less than 6). Preferably no hydrophilic emulsifiers are used.The emulsions are suitable for preparing UV-absorbing compositions such as sunscreens, moisturizers and after-sun lotions. The ability to use no, or little, hydrophilic emulsifiers is advantageous since, in, general, these emulsifiers are not biodegradable whereas hydrophobic emulsifiers generally are biodegradable.

Abstract: The invention consists of a new method of curing a polyester powder coating composition. The resin is cured by the use of an organotitanium or organozirconium derivative of an alkanolamine having the formula M.sub.3 [(OR).sub.3 N].sub.4 or O[M(OR).sub.3 N].sub.2 or R.sup.1 [OM(OR).sub.3 N].sub.x where M represents Ti or Zr, R represents a divalent aliphatic radical, x is 1 to 4 and R .sup.1 is a saturated hydrocarbyl group or a group containing one or more ether linkages. The method is suitable for use with both hydroxyl-rich and carboxyl-rich polyester resins and the cured coatings have desirable physical properties.

Abstract: An oil dispersion which is substantially transparent to visible light comprises an oil, particles of zinc oxide having an average size of from 0.005 to 0.15 micron and an organic dispersing agent. The solids content of the dispersion is at least 30 weight percent, its extinction coefficients at 308 nm (E(308)) and 360 nm (E(360)) wavelengths are both at least 9 liters per gram per centimeter and the ratio E(360):E(308) is in the range 0.75:1 to 1.5:1.A method of preparing the dispersion is also described in which the ingredients are milled together in the presence of a particulate grinding medium until the required particle size and optical properties are obtained.The dispersions are useful in sun-screening preparations and especially those products designed to provide a balanced protection from UVA and UVB radiation.

Abstract: a process for the preparation of anatase titanium dioxide having a high surface area and suitable as a catalyst support is described.The process involves forming an aqueous dispersion of titanium dioxide at a pH less than 3 and preferably less than 1 and depositing a first coating of a hydrous oxide of an element which acts as a rutilisation inhibitor and a second coating of a phosphate on the particles of titanium dioxide.The product of the process has a high surface area which is retained on heating for long periods at high temperature.A novel product is particulate anatase titanium dioxide which has been coated with a rutile inhibitor and a phosphate, has a specific surface area of at least 50 m.sup.2 /g and retains at least 80% of its surface area after heating at 800.degree. C. for 7 days.