Silicon Dioxide Dispersion

Abstract

The invention relates to a silicon dioxide dispersion that comprises a) an outer flowable phase containing 1) polymerizable monomers, oligomers and/or prepolymers that can be converted to polymers by non-radical reaction; and/or 2) polymers, and b) a disperse phase containing amorphous silicon dioxide. The inventive dispersion is characterized in that the average particle size d max of the silicon dioxide as measured by small angle neutron scattering (SANS) is between 3 and 50 nm at a maximum half-width of the distribution curve of 1.5 d max . Such a silicon dioxide dispersion can be easily manufactured even at higher concentrations of the disperse phase and can be used to produce polymer materials that have advantageous properties, especially advantageous mechanical properties.

1 - 26 . (canceled) 
   
   
       27 . A silicon dioxide dispersion, comprising:
 a) an external phase, said external phase comprising at least one of polymerizable monomers, oligomers, prepolymers convertible to polymers by nonradical reactions, or polymers,   b) a disperse phase comprising amorphous silicon dioxide particles,   
     wherein the average particle size d max  of said amorphous silicon dioxide particles as measured by small-angle neutron scattering is between 3 and 50 nm and wherein the half-width of the distribution curve is not more than 1.5 d max . 
   
   
       28 . The dispersion of  claim 27 , wherein the average particle size of said amorphous silicon dioxide particles is between 6 and 40 nm. 
   
   
       29 . The dispersion of  claim 28 , wherein the average particle size of said amorphous silicon dioxide particles is between 8 and 30 nm. 
   
   
       30 . The dispersion of  claim 29 , wherein the average particle size of said amorphous silicon dioxide particles is between 10 and 25 nm. 
   
   
       31 . The dispersion of  claim 27 , wherein the half-width of the distribution curve is not more than 1.2 d max . 
   
   
       32 . The dispersion of  claim 31 , wherein the half-width of the distribution curve is not more than d max . 
   
   
       33 . The dispersion of  claim 32 , wherein the half-width of the distribution curve is not more than 0.75 d max . 
   
   
       34 . The dispersion of  claim 27 , wherein said external phase is from 20-90% by weight of said dispersion. 
   
   
       35 . The dispersion of  claim 34 , wherein said external phase is from 30 to 80% by weight of said dispersion. 
   
   
       36 . The dispersion of  claim 35 , wherein said external phase is from 40 to 70% by weight of said dispersion. 
   
   
       37 . The dispersion of  claim 27 , wherein said disperse phase is from 10-80% by weight of said dispersion. 
   
   
       38 . The dispersion of  claim 37 , wherein said disperse phase is from 20-70% by weight of said dispersion. 
   
   
       39 . The dispersion of  claim 38 , wherein said disperse phase is from 30-60% by weight of said dispersion. 
   
   
       40 . The dispersion of  claim 27 , wherein said amorphous silicon dioxide particles are substantially spherical. 
   
   
       41 . The dispersion of  claim 27 , further comprising auxiliaries selected from the group consisting of solvents, plasticizers, crosslinkers, catalysts, stabilizers, dispersants, curing agents, reaction mediators and agents for influencing the fluidity of the dispersion. 
   
   
       42 . The dispersion of  claim 27 , wherein said dispersion is water-free. 
   
   
       43 . The dispersion of  claim 27 , wherein said external phase comprises at least one substance selected from the group consisting of polyols, polyamines, linear or branched polyglycol ethers, polyesters and polylactones. 
   
   
       44 . The dispersion of  claim 27 , wherein said external phase comprises at least one reactive resin. 
   
   
       45 . The dispersion of  claim 27 , wherein one or more of said polymerizable monomers, oligomers or prepolymers comprise main chains, and wherein said main chains comprise one or more C, O, N or S atoms. 
   
   
       46 . The dispersion of  claim 27 , wherein said external phase comprises polymerizable monomers that lack radically polymerizable double bonds and/or reactive resins. 
   
   
       47 . The dispersion of  claim 27 , wherein said external phase further comprises silanes. 
   
   
       48 . The dispersion of  claim 47 , wherein said amorphous silicon dioxide particles comprise silanol groups on their surfaces, and wherein said silanes are present in an amount of 60-150 mol % of the molar amount of the silanol groups on the surface of the amorphous silicon dioxide particles of said disperse phase. 
   
   
       49 . A process for preparing a silicon dioxide dispersion, comprising:
 a) providing:   i) an aqueous silicate solution,   ii) one or more constituents of an external phase   b) polycondensing said aqueous silicate solution to a silicate particle size of 3-50 nm to produce a silica sol,   c) adjusting said silica sol to an alkaline pH,   d) mixing said silica sol with said one or more constituents of an external fluid phase to produce a dispersion.   
   
   
       50 . The process of  claim 49 , further comprising concentrating said silica sol prior to said mixing of the silica sol with said external phase. 
   
   
       51 . The process of  claim 49 , further comprising removing water and/or other solvent constituents from said dispersion. 
   
   
       52 . The process of  claim 49 , wherein said aqueous silicate solution is an alkali metal silicate solution. 
   
   
       53 . The process of  claim 52 , wherein said alkali metal silicate solution comprises a sodium silicate solution or potassium silicate solution. 
   
   
       54 . The process of  claim 49 , wherein the concentration of said aqueous silicate solution is 20-50% by weight. 
   
   
       55 . The process of  claim 49 , wherein said silica sol is adjusted to a pH of between 10 and 12. 
   
   
       56 . The process of  claim 50 , wherein said silica sol is concentrated to a concentration of 30-40% by weight. 
   
   
       57 . The process of  claim 51 , wherein water is removed by means of a process selected from the group consisting of distillation, membrane separation, extraction and use of a molecular sieve. 
   
   
       58 . A process for producing a polymeric material comprising the use of a silicon dioxide dispersion of  claim 27 . 
   
   
       59 . The process of  claim 58 , wherein said polymeric material produced is selected from the group consisting of polyurethanes, polyureas, epoxy resins, polyester resins and polysiloxanes. 
   
   
       60 . The process of  claim 58 , wherein said polymeric material produced is a thermoset. 
   
   
       61 . The process of  claim 58 , wherein said polymeric material produced is a thermoplastic. 
   
   
       62 . The process of  claim 58 , wherein said polymeric material produced comprises a polymeric coating, a paint, an ink, or a foam. 
   
   
       63 . A polymeric material produced from a dispersion of  claim 27 .