Film forming composition comprising modified nanoparticles and modified nanoparticles for use in film forming compositions
The present invention relates to a film forming composition comprising a resin and modified nanoparticles comprising nanoparticles and adsorbed thereon a segmented copolymer, preferably a segmented blockcopolymer, comprising an adsorbing segment and a hydrophobic surface active segment, wherein the adsorbing segment has one or more functional groups that adsorb on the nanoparticles and wherein the hydrophobic segment is more hydrophobic than the resin providing surface migration of the nanoparticles. The invention also relates to novel modified particles and the use of the specified segmented copolymer of specified modified particles in a film forming composition for imparting thereto improved surface properties such as scratch resistance.
1. Modified nanoparticles comprising colloidal amorphous silica nanoparticles having an average diameter between 1 and 400 nanometers having adsorbed thereon a segmented copolymer, comprising an adsorbing segment and a hydrophobic surface active segment, wherein the adsorbing segment has one or more functional groups that adsorb on the nanoparticles, wherein the amount of copolymer on the nanoparticles is at most 100 wt % (relative to the total solid weight of the nanoparticles) and wherein the particle surface is esterified with mono-alcohol by chemical reaction between the hydroxyl groups of the alcohol and the silanol groups (Si—OH) of the amorphous colloidal silica particles.
2. Modified nanoparticles according to claim 1 , wherein the nanoparticles are amorphous silica nanoparticles and wherein the segmented copolymer is an A-B blockcopolymer produced by controlled radical polymerization producing a hydrophobic macromonomer block forming the surface active hydrophobic segment and a block having one or more basic functional groups.
3. Modified nanoparticles according to claim 2 , wherein the segmented copolymer comprises crosslinkable groups.
4. The modified nanoparticles of claim 1 , wherein the segmented copolymer comprises a blockcopolymer or a graft copolymer.
5. A film forming composition comprising a resin and the modified nanoparticles of claim 1 .
6. A scratch resistant coating, comprising a film forming composition comprising the modified nanoparticles according to claim 1 , wherein the modified nanoparticles are enriched at the surface of the coating.
7. The scratch resistant coating according to claim 6 , wherein the coating is a clear coating.