Unilever Patent Holdings B.v.

Crosfield Limited

Pq Silicas UK Limited

Crossfield Limited

Peter W Stanier

Derek Aldcroft

John R Newton

Ian P McKeown

James P Quinn

Pamela E Baines

Charlotte R Evans

Simon Cartwright

Simon R Stebbing

Bryan Rogers

An amorphous precipitated silica with controlled abrasivity and effective cleaning properties for use in an oral composition produced through comminution and classification of the silica to form particles with an oil absorption value of 150 cm/100 g or less, a weight median particle diameter dso of less than 3 &#x3bc;m and a dgo value, wherein 90% by weight of the particles have a diameter less than the dgo value, of 6 &#x3bc;m or less.

Silicas

An amorphous silica suitable for use in a dental composition has a weight mean particle size in the range 3 to 15 &#x3bc;m with at least 90 per cent by weight of particles having a size below 20 &#x3bc;m, a Radioactive Dentine Abrasion (RDA) determined on an aqueous slurry of the silica powder of 100 to 220, a Pellicle Cleaning Ratio (PCR), when incorporated in a dental composition at 10 per cent by weight, greater than 85, the ratio of PCR to RDA being in the range 0.4:1 to less than 1:1 and having a Plastics Abrasion Value (PAV) in the range 11 to 19. A silica having the above properties is prepared by a precipitation route. The silica made available by the invention is also useful as an anti-blocking agent in plastics.

Amorphous silica

Silica particles for incorporation into a dentifrice composition, preferably as a thickening agent, have a polyether glycol such as polyethylene glycol applied thereto in order to enhance dentifrice cohesion

Particulate materials for use in dentifrice compositions

An amorphous silica having an RDA value of between 40 and 70, an oil absorption capacity of between 90 and 145 cc/100 g and a moisture loss of less than 7% w/w, can be incorporated at a 10% to 25% loading into a transparent toothpaste having a refractive index of below 1.445, this toothpaste having an RDA value of less than 60.

Amorphous silicas and oral compositions

Inorganic material in particles form

An amorphous silica having an RDA value of between 30 and 70, an oil absorption capacity of between 100 and 155 cc/100 g and a moisture loss of less than 7% w/w, can be incorporated at a 10% to 25% loading into a transparent toothpaste having a refractive index of above 1.445, this toothpaste having an RDA value of between 30 and 60.

Amorphous silicas

Granular Compositions

A thickening system containing an amorphous silica and xanthan gum in a silica/xanthan gum weight ratio from 160:1 to 2:1, preferably 100:1 to 5:1, most preferably 30:1 to 6.5:1 can be used to stabilise and thicken cosmetic compositions containing alpha-hydroxy carboxylic acids.

Thickener for cosmetic composition

An amorphous silica has a pore volume in the range of from about 1.6 to about 2.5 cc g.sup.-1, a mean pore diameter in the range of from about 8.0 to about 20 nm, a surface area in the range from about 450 to about 1100 m.sup.2 g.sup.-1 and an oil absorption in the range of from about 250 to about 350 cc/100g.

Amorphous silicas suitable for use as abrasives in transparent toothpastes can be prepared by a precipitation route. These silicas are distinguished by having a BET surface area of 100 to 450 m.sup.2 /g, a weight mean particle size of 5 to 15 microns, a plastics abrasion value of 16 to 26, a mean pore diameter from 2 to 12 nm, a transmission of at least 70% in the refractive index range from 1.430 to 1.443 and an oil absorption in the range from about 70 to about 130 cm.sup.3 /g.

Silicas for use in transparent toothpaste compositions

A silica matting agent has a wax coating comprising a mixture of three waxes, i.e. hard microcrystalline, plasticising monocrystalline and synthetic polyethylene. The use of this ternary mixture gives the matting agent improved interaction with lacquers and improved sedimentation.

Silica products

A precipitated silica, suitable for use in toothpastes, has a high absorbency, i.e. 110 to 180 cm.sup.3 100 g, and good abrasivity with a plastics abrasion value of 12 to 20. The silica provides abrasion even at a relatively low particle size.

Precipitated silicas

Amorphous silicas suitable for use as abrasives in transparent toothpastes can be prepared by a precipitation route. These silicas are distinguished by having a BET surface area of 420 to 550 m.sup.2 /g, a weight mean particle size of 5 to 20 micron, a perspex abrasion value of 15 to 28, a mean pore diameter from 3 to 8 nm and a transmission of at least 70% in the R1 range from 1.444 to 1.460.

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Cheshire, United Kingdom

Peter W Stanier