Nissan Chemical Industries Limited

Nissan Chemical Corporation

Tohru Nishimura

Isao Ota

Kiyomi Ema

Kenji Tanimoto

Noriyuki Takakuma

Toshio Kasai

Naoki Kawashita

Kouji Yamaguchi

Takao Kaga

Yoshitane Watanabe

Yoshiyuki Kashima

Eiichiro Ishimizu

Yutaka Ohmori

Gen Yamada

Shigeru Mitsui

A polishing composition having silica-based abrasive grains and a polishing method. A polishing composition having silica particles, wherein on the basis of a colloidal silica dispersion of the silica particles, the dispersion has an Rsp of 0.15 to 0.7 as measured using pulse NMR, and the colloidal silica particles have a shape coefficient SF1 of 1.20 to 1.80, wherein Rsp is calculated based on equation (1):=()/()  (1)

Polishing composition comprising polishing particles having high water affinity

A method for producing an active silicic acid solution in which the existing amount of foreign matters as plate-like fine particles is reduced and a method for producing a silica sol in which such foreign matters are reduced. The method fulfills the following condition; the existing amount of plate-like fine particles having a length of one side of 0.2 to 4.0 &#x3bc;m and a thickness of 1 to 100 nm is measured to be 0% to 30% in accordance with measuring method A, the method including the steps of: preparing an active silicic acid solution by subjecting an alkali silicate aqueous solution having a silica concentration of 0.5% by mass to 10.0% by mass to cation-exchange to remove alkaline components; and filtering the active silicic acid solution through a filter whose removal rate of particles having a primary particle size of 1.0 &#x3bc;m is 50% or more.

Method for producing purified active silicic acid solution and silica sol

A method for producing an active silicic acid solution in which the existing amount of foreign matters as plate-like fine particles is reduced and a method for producing a silica sol in which such foreign matters are reduced. The method fulfills the following condition: the existing amount of plate-like fine particles having a length of one side of 0.2 to 4.0 &#x3bc;m and a thickness of 1 to 100 nm is measured to be 0% to 30% in accordance with measuring method A, the method including the steps of: preparing an active silicic acid solution by subjecting an alkali silicate aqueous solution having a silica concentration of 0.5% by mass to 10.0% by mass to cation-exchange to remove alkaline components; and filtering the active silicic acid solution through a filter whose removal rate of particles having a primary particle size of 1.0 &#x3bc;m is 50% or more.

To provide a method for producing an alkali silicate aqueous solution containing a reduced amount of foreign substance of plate-like fine particles and a method for producing a silica sol containing a reduced amount of foreign substance of plate-like fine particles. A method for producing an alkali silicate aqueous solution fulfilling the following condition: the existing amount of plate-like fine particles having a length of one side of 0.2 to 4.0 &#x3bc;m and a thickness of 1 to 100 nm is determined to be 0 to 30%. The method for producing an alkali silicate aqueous solution includes the steps of adjusting a silica concentration of an alkali silicate aqueous solution to 0.5 to 10.0% by mass and filtering the alkali silicate aqueous solution through a filter having a removal rate of particles with a primary particle size of 1.0 &#x3bc;m of 50% or more.

Method for producing purified alkali silicate aqueous solution and silica sol

There is provided an abrasive used for polishing a substrate which comprises silica as a main component, for example a rock crystal, a quartz glass for photomask, for CMP of an organic film, Inter Layer Dielectric (ILD) and shallow trench isolation of a semiconductor device, or for polishing a hard disk made of glass. A sol which particles are dispersed in a medium, wherein the particles have a particle size of 0.005 to 1 &#x3bc;m and comprise as a main component crystalline cerium oxide of the cubic system and as an additional component a lanthanum compound, a neodymium compound or a combination thereof, wherein the additional component is contained in X/(Ce+X) molar ratio of 0.001 to 0.5 in which X is lanthanum atoms, neodymium atoms or a combination thereof. The sol is prepared by reacting an aqueous solution which a cerium (III) salt is mixed with a lanthanum (III) salt and/or a neodymium (III) salt, with an alkaline substance to give a suspension in which cerium (III) hydroxide is homogeneously mixed with lanthanum (III) hydroxide and/or neodymium (III) hydroxide, and blowing oxygen or a gas containing oxygen into the suspension.

Cerium oxide sol and abrasive

The present invention provides an abrasive compound suitable for polishing the surface of a glass substrate for an optical disk platter or a magnetic disk platter. More specifically, the present invention provides an abrasive compound for a glass hard disk platter, characterized as comprising a stable slurry having water and, dispersed therein as an abrasive, cerium(IV) oxide particles having an average secondary particle size of 0.1 to 0.5 &#x3bc;m and containing CeOin a concentration of 0.2 to 30 wt %. Preferably, the present invention provides the above abrasive compound in which cerium amounts for 95% or more in terms of oxides of the total amount of rare earth elements in the abrasive.

Abrasive compound for glass hard disk platter

For aluminum disks and glass-made hard disks, those disks having a mean waviness of less than 3 &angst; are being desired in order to increase the density of memory capacity. The present invention provides polishing compositions that can give smoothly polished surfaces for the disks. The polishing compositions are polishing compositions for aluminum disks or substrates having silica on the surface thereof, which contain colloidal silica particle groups having different particle size distributions and have a SiO concentration of 0.5 to 50% by weight.

Polishing composition

Substantially monodisperse crystalline ceric oxide sols and processes for producing such sols are provided. Sols include crystalline ceric oxide particles having a particle size I (particle size converted from specific surface area by gas absorption method) ranging from 10 nm to 200 nm and a ratio of particle size II (particle size measured by dynamic light scattering method) to particle size I ranging from 2 to 6. Sols can be prepared by reacting a cerium (III) salt with an alkaline substance in an aqueous medium under an inert gas atmosphere to obtain a suspension of cerium (III) hydroxide, immediately blowing oxygen or a gas containing oxygen into the suspension to obtain a sol comprising crystalline ceric oxide particles, and wet grinding the resulting sol. Sols are also prepared by calcining cerium carbonate at a temperature of 300 to 1100&deg; C. to give cerium oxide particles, and wet-grinding the resulting particles.

Crystalline ceric oxide sol and process for producing the same

Production of an alumina powder characterized by having a single or multiple crystal structure selected from the group consisting of &ggr;, &dgr; and &thgr;-forms, a primary particle size of 10 to 50 nm, a mean secondary particle size of 100 to 500 nm, and a granular primary particle shape, or an alumina powder characterized by having an a-form crystal structure, a primary particle size of 60 to 150 nm, a mean secondary particle size of 200 to 500 nm, and a granular primary particle shape, using as a raw material an alumina hydrate comprising rectangular plate-like primary particles having a boehmite structure and having a length of one side of 10 to 50 nm; and preparation of a polishing composition comprising the alumina powder, water and a polishing accelerator.

Alumina powder, process for producing the same and polishing composition

The present invention relates to a polishing composition for polishing alumina disks, polishing substrates having silica surfaces and semiconductor wafers, comprising a stable aqueous silica sol containing moniliform colloidal silica particles having a ratio (D /D ) of a particle diameter D nm (as measured by dynamic light scattering method) to a mean particle diameter D (as measured by nitrogen absorption method) of 3 or more, wherein D is between 50 to 800 nm and D is between 10 to 120 nm, said moniliform colloidal silica particles being composed of spherical colloidal silica particles and a metal oxide-containing silica bond which bonds these spherical colloidal silica particles together, wherein the spherical colloidal silica particles are linked together in rows in only one plane by observation through an electron microscope, and further wherein said polishing composition contains 0.5 to 50% by weight of said moniliform colloidal silica particles.

According to the present invention, a process is provided for producing crystalline ceric oxide particles having a particle diameter of 0.005 to 5 &mgr;m, which comprises the steps of reacting a cerium (III) salt with an alkaline substance in an (OH)/(Ce ) molar ratio of 3 to 30 in an aqueous medium in an inert gas atmosphere to produce a suspension of cerium (III) hydroxide, and blowing oxygen or a gas containing oxygen into the suspension at a temperature of 10 to 95&deg; C. and at an atmospheric pressure.

Polishing abrasive of crystalline ceric oxide particles having surfaces modified with hydroxyl groups

A polishing composition for an aluminum disk includes water, an alumina abrasive agent and a polishing accelerator. The polishing accelerator is preferably basic aluminum nitrate. A process for polishing an aluminum disk using the polishing composition is also provided.

Polishing composition for aluminum disk and polishing process therewith

According to the present invention, a process is provided for producing crystalline ceric oxide particles having a particle diameter of 0.005 to 5 .mu.m, which comprises the steps of reacting a cerium (III) salt with an alkaline substance in an (OH)/(Ce.sup.3+) molar ratio of 3 to 30 in an aqueous medium in an inert gas atmosphere to produce a suspension of cerium (III) hydroxide, and blowing oxygen or a gas containing oxygen into the suspension at a temperature of 10 to 95.degree. C. and at an atmospheric pressure.

Growing community of inventors

Sodegaura, Japan

Tohru Nishimura