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Aqueous organoalkoxysilane/metal oxide sol-gel compositions

  • US 4,814,017 A
  • Filed: 10/03/1986
  • Issued: 03/21/1989
  • Est. Priority Date: 10/03/1986
  • Status: Expired due to Term
First Claim
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1. A method of making an organoalkoxysilane/metal oxide sol-gel composition in an aqueous medium comprising the steps of:

  • a. adding a less than equivalent quantity of water to an organoalkoxysilane of the general formula
    
    
    space="preserve" listing-type="equation">R.sub.x Si(OR'"'"').sub.4-x wherein R is an organic radical, R'"'"' is a low molecular weight alkyl radical, and x is at least one and less than 4;

    b. partially hydrolyzing said organoalkoxysilane according to the general reaction
    
    
    space="preserve" listing-type="equation">R.sub.4 Si(OR'"'"').sub.4-x +yH.sub.2 O→

    R.sub.x Si(OR'"'"').sub.4-x-y (OH).sub.y +yR'"'"'OH wherein y is at least one and less than 4-x, until said quantity of water is essentially completely reacted;

    c. adding to said essential anhydrous partially hydrolyzed organoalkoxysilane a metal alkoxide of the general formula M(OR")z wherein M is a metal selected from the group consisting of titanium and zirconium, R" is a low molecular weight alkyl radical, and z is the valence of M;

    d. reacting said metal alkoxide with said partially hydrolyzed organoalkoxysilane according to the following general reaction ##STR5## until substantially all of said metal alkoxide has reacted with said partially hydrolyzed organoalkoxysilane to form an oxide network; and

    e. adding sufficient water to essentially completely hydrolyze said composition to form an aqueous sol.

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