Silane-modified binder dispersions

1. A method for stabilizing inorganic nanoparticles, wherein the method comprises forming an aqueous formulation comprising

A) a silane-modified copolymer a1) comprising groups of general formula (1)

—Si(R 1 O) 2 R 2   (1)

wherein

R 1 is a C 2 - to C 8 -alkyl radical; and

R 2 is (R 1 O) or a C 1 - to C 5 -alkyl radical,

and

wherein the silane-modified copolymer is built up from

I) a hydroxy-functional hydrophobic polymer containing as builder monomers

Ia) (meth)acrylic acid esters having C 1 - to C 18 -hydrocarbon radicals in the alcohol part and/or vinylaromatics and/or vinyl esters;

Ib) hydroxy-functional monomers; and

IS1) silane-functional monomers capable of polymerization; and

II) a hydroxy-functional hydrophilic polymer containing as builder components

IIa) (meth)acrylic acid esters having C 1 - to C 18 -hydrocarbon radicals in the alcohol part and/or vinylaromatics and/or vinyl esters;

IIb) hydroxy-functional monomers; and

IIc) acid-functional monomers,

and a polyorganosiloxane a2) containing hydroxyl groups;

B) inorganic particles, which are optionally surface modified, and having an average particle size (z-mean), as determined by means of dynamic light scattering in dispersion, of less than 200 nm, wherein said inorganic particles B) are inorganic nanoparticles in a colloidally disperse form in organic solvents or in water; and

C) water;

wherein the inorganic particles are introduced by mechanical stirring.

2. The method of claim 1 , wherein said silane-functional monomer IS1), which is capable of polymerization, is a compound of the general formula (2)

(R 1 O) 2 R 2 Si—(CH═CH 2 )  (2)

wherein

R 1 is a C 2 - to C 8 -alkyl radical; and

R 2 is (R 1 O) or a C 1 - to C 5 -alkyl radical;

and/or a compound of the general formula (3)

(R 1 O) 2 R 2 Si(CH 2 ) m —O(CO)—(CR 3 ═CH 2 )  (3)

wherein

R 1 is a C 2 - to C 8 -alkyl radical;

R 2 is (R 1 O) or a C 1 - to C 5 -alkyl radical;

R 3 is H or CH 3 ; and

m is 1 to 4.

3. The method of claim 1 , wherein said silane-functional monomer IS1), which is capable of polymerization, is selected from the group consisting of vinyltriethoxysilane, vinyltrisisopropoxysilane, vinyl-tris-(2-methoxyethoxy)silane, vinylmethyldiethoxysilane, vinylmethyldiisopropoxysilane, vinylethyldiethoxysilane, 3-(triethoxysilyl)-propyl methacrylate or 3-(tris-isopropoxysilyl)-propyl methacrylate, vinylphenyldiethoxysilane, vinylphenylmethylethoxysilane or vinyltri-t-butoxysilane.

4. The method of claim 1 , wherein said polyorganosiloxane a2) containing hydroxyl groups is a compound of the general formula (I)

wherein

X is an aliphatic, optionally branched C 1 to C 10 radical or

a [—CH 2 —O—(CH 2 ) p —]Si unit, wherein r is an integer from 1 to 4;

R is a —CH(OH)Y group, wherein

Y is a —CH 2 —N(R 2 R 3 ) group, wherein

R 2 is H or a methyl, ethyl, n-propyl, iso-propyl, or cyclohexyl radical, or a 2-hydroxyethyl, 2-hydroxypropyl, or 3-hydroxypropyl radical; and

R 3 is a 2-hydroxyethyl, 2-hydroxypropyl, or 3-hydroxypropyl radical,

R 1 is, identically or differently, H or a C 1 - to C 10 -hydrocarbon radical optionally containing hetero atoms; and

n is an integer from 1 to 40.

5. The method of claim 1 , wherein said polyorganosiloxane a2) having the general formula (I) has a number-average molecular weight in the range of from 200 to 3,000 g/mol and an average OH functionality of at least 1.8.

6. The method of claim 1 , wherein said polyorganosiloxane a2) having the general formula (I) has a number-average molecular weight in the range of from 250 to 2,250 g/mol.

7. The method of claim 1 , wherein said inorganic particles B) are selected from the group consisting of inorganic oxides, mixed oxides, carbides, borides and nitrides of elements of main group II to IV and/or elements of subgroup I to VIII of the periodic table, including the lanthanides.

8. The method of claim 1 , wherein said inorganic particles B) are surface-modified inorganic nanoparticles.