Polishing compositions based on cerium and process for the preparation thereof

Claim 2

A cerium based polishing composition comprising a polishing agent comprising a ceric oxide and a boron compound.

Claim 3

The composition as defined by claim 1, wherein said polishing agent comprises ceric oxide or a composition containing ceric oxide.

Claim 4

The composition as defined by claim 1, wherein said ceric oxide is present in the composition in an amount of at least 30% by weight.

Claim 5

The composition as defined by claim 3, wherein said ceric oxide is a powder having particle dimensions of less than 20 μm.

Claim 6

The composition as defined by claim 4, wherein said ceric oxide is a powder having particle dimensions between 0.1 μm and 10 μm.

Claim 7

The composition as defined by claim 5, wherein said ceric oxide has a specific surface area of from about 1 m 2 /g to 35 m 2 /g.

Claim 8

The composition as defined by claim 6, wherein said ceric oxide has a specific surface area of between about 3 m 2 /g to 10 m 2 /g.

Claim 9

The composition as defined by claim 2, wherein said ceric oxide composition comprises a crystallographic phase of a CeO 2 based composition and a crystallographic phase comprising a pyrosilicate of rare earth values corresponding to the formula Ln 2-x Ce x Si 2 O 7 , wherein Ln is at least one element selected from the group consisting of lanthanides, yttrium, and mixtures thereof, and x is greater than or equal to 0 and less than 2.0.

Claim 10

The composition as defined by claim 8, wherein said composition comprises between 75% to 95% by weight of rare earth values in the form of oxides and has a percentage of ceric oxide relative to the total weight of rare earth oxides of from about 60% to 85%, and from about 5% to 25% by weight silicon expressed as SiO 2 .

Claim 11

The composition as defined by claim 2, said ceric oxide composition further comprising at least one colorless oxide of a rare earth value other than cerium.

Claim 12

The composition as defined by claim 10, wherein said ceric oxide composition comprises from about 40% to 99.5% by weight ceric oxide and from about 0.5% to 60% by weight of rare earth oxides.

Claim 13

The composition as defined by claim 1, wherein said boron compound is selected from the group consisting of boric acids, metallic borates and ammonium borates, said borates being present in an anhydrous or a hydrated form.

Claim 14

The composition as defined by claim 11, wherein said boron compound is selected from the group consisting of orthoboric acid or its precursor B 2 O 3 , metaboric acid, pyroboric acid, tetraboric acid, sodium tetraborate, sodium tetraborate decahydrate, sodium tetraborate pentahydrate, sodium metaborate, sodium metaborate tetrahydrate, potassium metaborate, potassium pentaborate tetrahydrate, potassium tetraborate octahydrate, ammonium pentaborate tetrahydrate and ammonium tetraborate tetrahydrate.

Claim 15

The composition as defined by claim 12, wherein said boron compound is orthoboric acid or its precursor B 2 O 3 .

Claim 16

The composition as defined by claim 12, wherein said boron compound is borax.

Claim 17

The composition as defined by claim 1, wherein said boron compound expressed as elemental boron is present in an amount of between 0.05% to 5% by weight relative to said polishing agent.

Claim 18

The composition as defined by claim 16, wherein said boron compound is present in an amount between 0.05% to 1.0%.

Claim 19

The composition as defined by claim 1, further comprising an aluminum silicate.

Claim 20

The composition as defined by claim 18, wherein said aluminum silicate is a clay or an organophilic clay.

Claim 21

The composition as defined by claim 19, wherein said clay is selected from the group consisting of kaolin, serpentine, montmorillonite, vermiculite, halloysite, chlorite, attapulgite and sepiolite clays.

Claim 22

The composition as defined by claim 18, wherein said clay is selected from the group consisting of montmorillonite, halloysite and attapulgite clays.

Claim 23

The composition as defined by claim 21, wherein said clay is a montmorillonite clay.

Claim 24

The composition as defined by claim 18, wherein said aluminum silicate expressed as aluminum silicate is present in an amount of between 0.5% and 10% by weight relative to said polishing agent.

Claim 25

The composition as defined by claim 23, wherein said aluminum silicate is present in an amount of between 1.0% to 3.0% by weight.

Claim 26

A process for preparing a polishing agent containing ceric oxide comprising the steps of: (a) mixing simultaneously and continuously a solution of a cerium salt, a solution containing a base, and a solution of at least one acid, salt or mixture of an acid and salt, the anion or anions of which are capable of forming insoluble rare earth compounds, the number of basic equivalents in said solution being at least equal to the number of cerium equivalents at a pH of at least 6.0 to form a precipitate; (b) filtering said precipitate; (c) drying said precipitate; and (d) calcining said precipitate.

Claim 27

A process for preparing a polishing agent containing ceric oxide comprising the steps of: (a) mixing simultaneously and continuously a solution of a cerium salt, a solution containing a base, and a solution of at least one acid, salt or mixture of an acid and salt, the anion or anions of which are capable of forming insoluble rare earth compounds, the number of basic equivalents in said solution being at least equal to the number of cerium equivalents at a pH of at least 6.0 to form a precipitate; (b) filtering said precipitate; (c) drying said precipitate; and (d) calcining said precipitate.

Claim 28

The process as defined by claim 25, wherein an aqueous solution of at least one trivalent rare earth value is added.

Claim 29

The process as defined by claim 25, wherein said anion is selected from the group consisting of fluoride, sulfate, borate and phosphate.

Claim 30

A process for preparing a polishing agent containing ceric oxide as a composition, said process comprising the steps of: (a) mixing simultaneously a solution of a cerium salt, a solution containing a base, a solution containing an aqueous solution of a salt of at least one trivalent rare earth compound or yttrium and an aqueous solution of at least one oxygen derivative of silicon capable of forming insoluble rare earth compounds for form a precipitate; (b) filtering said precipitate; (c) drying said precipitate; and (d) calcining said precipitate at a temperature of at least 850° C. or higher.

Claim 31

A process for preparing a polishing agent containing ceric oxide as a composition, said process comprising the steps of: (a) mixing simultaneously a solution of a cerium salt, a solution containing a base, a solution containing an aqueous solution of a salt of at least one trivalent rare earth compound or yttrium and an aqueous solution of at least one oxygen derivative of silicon capable of forming insoluble rare earth compounds for form a precipitate; (b) filtering said precipitate; (c) drying said precipitate; and (d) calcining said precipitate at a temperature of at least 850° C. or higher.

Claim 32

A process for preparing a polishing agent containing a composition containing a ceric oxide and at least one colorless oxide of a rare earth value comprising the steps of; (a) mixing simultaneously and continuously a solution of a cerium salt, a solution containing a base, and a solution of at least one trivalent salt of a rare earth value, said trivalent salt being selected from the group consisting of the lanthanides, yttrium, and mixtures thereof, the oxide of which is colorless and having the number of basic equivalents higher than or equal to said cerium and rare earth equivalents, at a pH of at least 6.0 to form a precipitate; (b) filtering said precipitate; (c) drying said precipitate; and (d) calcining said precipitate.

Claim 33

A process for preparing a polishing agent containing a composition containing a ceric oxide and at least one colorless oxide of a rare earth value comprising the steps of; (a) mixing simultaneously and continuously a solution of a cerium salt, a solution containing a base, and a solution of at least one trivalent salt of a rare earth value, said trivalent salt being selected from the group consisting of the lanthanides, yttrium, and mixtures thereof, the oxide of which is colorless and having the number of basic equivalents higher than or equal to said cerium and rare earth equivalents, at a pH of at least 6.0 to form a precipitate; (b) filtering said precipitate; (c) drying said precipitate; and (d) calcining said precipitate.

Claim 34

A process for the preparation of a polishing composition comprising: (a) mixing a polishing agent containing ceric oxide with a solution to form a polishing bath; and (b) adding to said polishing bath a boron compound.

Claim 35

A process for the preparation of a polishing composition comprising: (a) mixing a polishing agent containing ceric oxide with a solution to form a polishing bath; and (b) adding to said polishing bath a boron compound.

Claim 36

The process as defined by claim 30, wherein said process further comprises adding aluminum silicate to said polishing bath.

Claim 37

The process as defined by claim 30, wherein said process further comprises the step of initially preparing a powder mixture of said polishing agent and said boron compound.

Claim 38

The process as defined by claim 30, wherein said polishing agent, expressed as CeO 2 , is present in an amount of between 30 grams to 300 grams per liter of said bath.