Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
138 words
A surface-modified pigment of natural kaolin or kaolin-like material intended for use as a pigment in paper and coats of paint, characterised in that it has on its pigment particles precipitated primary and secondary layers bonded to one another by hydrogen or ion bonding, the primary layer consisting of anionic Al 2 O 3 ―SiO 2 hydrate gel having a molar ratio of SiO 2 :Al 2 O 3 of from 3 to 30, preferably from 8 to 15, and being present in an amount corresponding to from 2 to 15% by weight of SiO 2 , based upon the original quantity of kaolin or kaolin-like material, and the secondary layer consisting of a polymeric binder which is included in a quantity of at least 2% by weight, based upon the original quantity of kaolin or kaolin-like material.
Claim 2
Dependent Claim
138 words
A surface-modified pigment of natural kaolin or kaolin-like material intended for use as a pigment in paper and coats of paint, characterised in that it has on its pigment particles precipitated primary and secondary layers bonded to one another by hydrogen or ion bonding, the primary layer consisting of anionic Al 2 O 3 ―SiO 2 hydrate gel having a molar ratio of SiO 2 :Al 2 O 3 of from 3 to 30, preferably from 8 to 15, and being present in an amount corresponding to from 2 to 15% by weight of SiO 2 , based upon the original quantity of kaolin or kaolin-like material, and the secondary layer consisting of a polymeric binder which is included in a quantity of at least 2% by weight, based upon the original quantity of kaolin or kaolin-like material.
Claim 3
Dependent Claim
28 words
A pigment as claimed in claim 1, characterised in that the polymeric binder of the secondary layer consists of hydrogen-bonded gelatin, urea formaldehyde resin, polyacrylate or oligomerous silica.
Claim 4
Dependent Claim
30 words
A pigment as claimed in claim 2, characterised in that polyethoxy compounds in the form of non-ionic tensides or polyethylene glycols are included as cross-linking agents in the hydrogen bond.
Claim 5
Dependent Claim
29 words
A pigment as claimed in claim 1, characterised in that the polymeric binder of the secondary layer consists of ion-bonded cationic starch, cation-active polyamides or high-condensed cation-active urea resins.
Claim 6
Dependent Claim
196 words
A process of producing a surface-modified pigment as claimed in any one of claims. 1-4; characterised in that pigment particles consisting of kaolin or kaolin-like material are coated with a primary and a secondary layer under the action of hydrogen or ion bonding by dispersing the pigment particles in water and by admixing to the dispersion a water glass solution and a solution of aluminium salt and acid in order to precipitate at a pH of from 1.5 to 5.0, preferably from 2.5 to 3.5, a layer of anionic Al 2 O 3 ―SiO 2 hydrate gel which serves as the primary layer and has a composition corresponding to a molar ratio of SiO 2 :Al 2 O 3 of 3-30, preferably from8 to 15, and which gel is added in a quantity corresponding to from 2 to 15% by weight of Si0 2 , based upon the original amount of kaolin or kaolin-like material, and by further admixing a polymeric binder in an amount of at least 2% by weight, based upon the original amount of kaolin or kaolin-like material, in order to form the secondary layer, and that the surface-modified pigment is not dried.