The present invention provides alumina hydrate particles, a flame retardant and a resin composition that are each for an electric wire/cable covering material improvable in flame retardancy and mechanical properties while the covering material keeps acid resistance; such an electric wire/cable; and producing methods thereof. The alumina hydrate particles of the present invention for electric wire/cable covering material have an average particle size of 0.5 to 2.5 μm, and having a primary particle variation R of 24% or less, the variation R being represented by the following expression:
primary particle variation R (%)=“standard deviationσ(μm) of major axis diameters of the primary particles”/“average value(μm) of the major axis diameters of the primary particles”×100.

The present invention provides alumina hydrate particles, a flame retardant and a resin composition that are each for an electric wire/cable covering material improvable in flame retardancy and mechanical properties while the covering material keeps acid resistance; such an electric wire/cable; and producing methods thereof. The alumina hydrate particles of the present invention for electric wire/cable covering material have an average particle size of 0.5 to 2.5 μm, and having a primary particle variation R of 24% or less, the variation R being represented by the following expression:
primary particle variation R (%)=“standard deviationσ(μm) of major axis diameters of the primary particles”/“average value(μm) of the major axis diameters of the primary particles”×100.

Provided are a method for producing boehmite nanoparticles and an apparatus for producing the same, and more particularly, a method for producing boehmite nanoparticles and an apparatus for producing the same, which allow continuous production of nano-sized boehmite nanoparticles in a uniform size. The method for producing boehmite nanoparticles includes (S1) supplying a mixture including an aluminum hydroxide and an organic acid to a reaction unit; and (S2) heating and pressurizing the mixture supplied to the reaction unit simultaneously and sequentially.

Provided are a method for producing boehmite nanoparticles and an apparatus for producing the same, and more particularly, a method for producing boehmite nanoparticles and an apparatus for producing the same, which allow continuous production of nano-sized boehmite nanoparticles in a uniform size. The method for producing boehmite nanoparticles includes (S1) supplying a mixture including an aluminum hydroxide and an organic acid to a reaction unit; and (S2) heating and pressurizing the mixture supplied to the reaction unit simultaneously and sequentially.

A process for preparing crystalline boehmite includes combining a stoichiometric amount of flash calcined gibbsite (AI.sub.2O.sub.3) and gibbsite (Al(OH).sub.3) in a pressurizable reaction vessel; heating the flash calcined gibbsite and gibbsite in the reaction vessel to a temperature of about 200° C. to about 280° C. and for a time sufficient to form crystalline boehmite. A crystalline boehmite exhibiting a crystallite from about 600 Å to about 850 Å when measured in the 120 direction of the crystallographic space group Cmcm.

A process for preparing crystalline boehmite includes combining a stoichiometric amount of flash calcined gibbsite (AI.sub.2O.sub.3) and gibbsite (Al(OH).sub.3) in a pressurizable reaction vessel; heating the flash calcined gibbsite and gibbsite in the reaction vessel to a temperature of about 200° C. to about 280° C. and for a time sufficient to form crystalline boehmite. A crystalline boehmite exhibiting a crystallite from about 600 Å to about 850 Å when measured in the 120 direction of the crystallographic space group Cmcm.

The invention provides highly reactive nano-sized alumina particle compositions, including alumina compositions with a BET surface areas on the order of 2000 m.sup.2/g. Also disclosed are impregnated alumina supports comprising materials that are metal oxides or carbonates. Methods for the synthesis and fabrication of these compositions are provided, along methods for the use of these compositions as sorbents.

The invention provides highly reactive nano-sized alumina particle compositions, including alumina compositions with a BET surface areas on the order of 2000 m.sup.2/g. Also disclosed are impregnated alumina supports comprising materials that are metal oxides or carbonates. Methods for the synthesis and fabrication of these compositions are provided, along methods for the use of these compositions as sorbents.

A boehmite structure includes a plurality of boehmite particles where adjacent boehmite particles are bonded to each other. The boehmite structure has a porosity of 30% or less. A method of producing a boehmite structure includes obtaining a mixture by mixing hydraulic alumina with a solvent including water, and pressurizing and heating the mixture under a condition of a pressure of 10 to 600 MPa and a temperature of 50 to 300° C.

A boehmite structure includes a plurality of boehmite particles where adjacent boehmite particles are bonded to each other. The boehmite structure has a porosity of 30% or less. A method of producing a boehmite structure includes obtaining a mixture by mixing hydraulic alumina with a solvent including water, and pressurizing and heating the mixture under a condition of a pressure of 10 to 600 MPa and a temperature of 50 to 300° C.