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Uretidione dimer of isophorone diisocyanate and method of preparation

  • US 4,476,054 A
  • Filed: 08/13/1981
  • Issued: 10/09/1984
  • Est. Priority Date: 08/13/1980
  • Status: Expired due to Fees
First Claim
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1. A process for producing a substantially isocyanate-free uretidione dimer of isophorone diisocyanate, which is more than 98% decomposable by heat to isophorone diisocyanate, which comprises:

  • dimerizing isophorone diisocyanate in the presence of a catalyst of the formula
    
    
    space="preserve" listing-type="equation">X.sub.m P(NR.sub.2).sub.3-m whereinm=0, 1, or 2,X=Cl, OR or R, andR is selected from the group consisting of the same or different C1 -C8 -alkyl radical, benzyl radical, phenylethyl radical, cyclohexyl radical, and cyclopentyl radical, at temperatures of 0°

    -80°

    C.,isolating the resulting 1,3-diazacyclobutane-2,4-dione after 5-70% conversion, without previous inactivation of the catalyst, from the reaction mixture as the residue of a thin film distillation and isolating the catalyst and monomer as the distillate of said distillation.

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