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

• Current Assignee: Chemische Werke Huls Aktiengesellschaft
• Original Assignee: Chemische Werke Huls Aktiengesellschaft
• Inventors: Wolf, Elmar, Disteldorf, Josef, Hubel, Werner
• Primary Examiner(s): Torrence, Dolph H.
• Application Number:
  US06/292,499
• Time in Patent Office: 1,153 Days
• Field of Search: 260/239 A
• US Class Current: 540/202
• CPC Class Codes: C07D 229/00 Heterocyclic compounds containing rings of less than five members having two nitrogen atoms as the only ring hetero atoms
• CPC Class Codes: C08G 18/798 containing urethdione groups
• CPC Class Codes: C08G 2150/20 Compositions for powder coatings

Abstract

A process for producing a substantially isocyanurate-free uretidione dimer of isophorone diisocyanate, which is more than 98% decomposable by heat to isophorone diisocyanate, which comprises dimerizing isophorone diisocyanate, optionally in an inert organic solvent, in the presence of a catalyst of the formula X_m P(NR₂)_3-m wherein m=0, 1, 2; X=Cl OR of R wherein R is selected from the group consisting of the same or different aklyl radical, aralkyl radical, cycloalkyl radical, substituted cycloalkyl radical and radicals wherein two or more of the aforementioned radicals form a hererocyclic ring together with the nitrogen atom; 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.

Claims

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

wherein

m=0, 1, or 2,

X=Cl, OR or R, and

R 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.

2. The process of claim 1 wherein said dimerization reaction is carried out at 10°

-30°

C.

3. The process of claim 1 wherein said isolation is carried out after 20-50% conversion has occured.

4. The process of claim 1 wherein said catalyst has the formula

5. The process of claim 4 wherein said catalyst is present in an amount of 0.5-2% by weight.

6. The process of claim 1 or 4 wherein said catalyst has the formula

7. The process of claim 1 wherein any unreacted isophorone diisocyanate recovered from the reaction mixture is returned to the reaction mixture.

8. The process of claim 1 wherein R is methyl or ethyl.

12. The uretidione dimer prepared by the process of claim 7.

9. An uretidione dimer of isophorone diisocyanate which is substantially free of isocyanurate and which is more than 98% decomposable by heat to isophoronediisocyanate.

10. The uretidione dimer of claim 9 which has an NCO content of 16.8-18%.

11. The uretidione dimer of claim 9 wherein the content of monomeric IPDI is less than 1% by weight.