Organic compounds -- part of the class 532-570 series – Organic compounds – Four or more ring nitrogens in the bicyclo ring system
Reexamination Certificate
2001-07-06
2002-09-17
Sergent, Rabon (Department: 1711)
Organic compounds -- part of the class 532-570 series
Organic compounds
Four or more ring nitrogens in the bicyclo ring system
C252S182200, C252S182210, C528S045000, C528S052000, C528S053000, C528S054000, C528S073000, C528S067000, C540S202000, C544S193000, C548S951000, C548S952000, C560S115000, C560S354000, C560S355000, C564S032000
Reexamination Certificate
active
06452003
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for preparing low-odor and storage-stable monomer-containing polyisocyanurates from isophorone diisocyanate.
2. Discussion of the Background
Polyisocyanurates as polyisocyanate adducts are valuable components for producing high-quality coatings having good mechanical properties and good light and weather resistance. Polyisocyanurates derived from isophorone diisocyanate (IPDI) are also used as raw material for elastomer applications. Here, it can be desirable for the IPDI-based polyisocyanurate, also referred to as IPDI trimer, to be used in monomer containing form.
Polyisocyanurates are typically obtained by the catalytic trimerization of suitable isocyanates. Suitable isocyanates include, for example, aromatic, cycloaliphatic and aliphatic bifunctional and higher-functional polyisocyanates. Suitable catalysts include, for example, tertiary amines (U.S. Pat. No. 3,996,223), alkali metal salts of carboxylic acids (CA 2 113 890; EP 056 159), quaternary ammonium salts (EP 798 299; EP 524 501; U.S. Pat. No. 4,186,255; U.S. Pat. No. 5,258,482; U.S. Pat. No. 4,503,226; U.S. Pat. No. 5,221,743), amino silanes (EP 197 864; U.S. Pat. No. 4,697,014) and quaternary hydroxyalkylammonium salts (EP 017 998; U.S. Pat. No. 4,324,879). Depending on the catalyst, the use of various cocatalysts is also possible, e.g. OH-functional compounds or Mannich bases derived from secondary amines and aldehydes or ketones.
To carry out the trimerization, the polyisocyanates are allowed to react in the presence of the catalyst, if desired with addition of solvents and/or auxiliaries, until the desired conversion has been reached. In this context, the term “partial trimerization” is typical since the desired conversion is generally significantly below 100%. The reaction is then stopped by deactivation of the catalyst. Deactivation is achieved by addition of a catalyst inhibitor such as p-toluene sulfonic acid, hydrogen chloride or dibutyl phosphate; and unavoidably and often undesirably results in the contamination of the resulting polyisocyanate containing isocyanurate groups.
In the trimerization of isocyanates on an industrial scale, the use of quaternary hydroxyalkylammonium carboxylates as oligomerization catalysts is particularly advantageous. This type of catalyst is thermally labile and allows targeted thermal deactivation, so that it is not necessary to stop the trimerization by addition of potentially quality-reducing inhibitors when the desired conversion has been reached.
Monomer-containing IPDI trimer, which is suitable, for example, for elastomer applications, has an NCO content of at least 25% by weight for viscosity reasons. The polyisocyanurate is prepared by partial trimerization of IPDI in the presence of one or more suitable catalysts. The catalyst must then either be removed completely from the reaction solution, which can be achieved by short-path distillation or thin-film evaporation, or be deactivated because the trimer is not storage-stable in the presence of active catalyst residues. If the NCO content of the IPDI polyisocyanurate obtained is below the desired level, it can easily be adjusted as desired by diluting the solution with monomeric IPDI.
Alkali metal salts of carboxylic acids are not well suited as catalysts for the preparation of monomer containing IPDI trimer since these catalysts can be removed from the reaction products only with difficulty, if at all. With respect to the available amine-containing catalysts, it has been found that the resulting IPDI trimer solutions usually have a distinctly perceptible and undesirable odor, which is sufficiently pronounced to be noticeable and unpleasant in the final application. In industrial practice, the undesirable odor is eliminated by freeing the reaction solution after partial trimerization and catalyst deactivation of excess IPDI, of odor-imparting components and possibly of undesirable catalyst inhibitors. This freeing is generally achieved by short-path distillation or thin-film evaporation. The solid resin that has been freed of monomer is subsequently converted by the addition of fresh IPDI into the desired, low-odor and monomer-containing IPDI polyisocyanurate.
The sequence of partial trimerization/deactivation, monomer removal/purification and subsequent dissolution of the solid resin in the monomer is very complicated. The monomer removal step is particularly time-consuming and costly, and it limits the capacity or and creates a bottleneck in the known processes.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for preparing monomer containing polyisocyanurates that avoids the problems associated with conventional processes.
It is another object of the present invention to provide a more economical process for preparing monomer-containing polyisocyanurates.
It is another object of the present invention to provide a process for preparing low-odor monomer-containing polyisocyanurates.
It is another object of the present invention to provide a process for preparing storage-stable monomer-containing polyisocyanurates.
It is another object of the present invention to provide a process for preparing low-odor and storage-stable monomer-containing polyisocyanurates from isophorone diisocyanate.
It is another object of the present invention to provide a process for preparing monomer-containing polyisocyanurates which avoids the monomer removal step.
It is another object of the present invention to provide a more economical process for preparing low-odor and storage-stable monomer-containing polyisocyanurates from isophorone diisocyanate which avoids the need for the monomer removal step.
It is another object of the present invention to provide low-odor and storage-stable monomer-containing polyisocyanurates.
It is another object of the present invention to provide low-odor and storage-stable monomer-containing polyisocyanurates that avoids the need for quality-reducing catalyst inhibitors.
It is another object of the present invention to provide low-odor and storage-stable monomer-containing polyisocyanurates that avoids the need for monomer removal and/or chemical deactivation of the isophorone diisocyanate trimerization catalyst.
The objects of the present invention, and others, may be accomplished with the present invention, the first embodiment of which provides a process, including:
partially trimerizing isophorone diisocyanate in the presence of a catalyst having the formula:
[R—NX
3
]
⊕
Y
⊖
wherein R and X are butyl groups and Y
− is CH
3
COO
−
; or
wherein R is a benzyl group, Y
−
is a carboxylate anion having from 4 to 8 carbon atoms and each X is an alkylene group having from 2 to 3 carbon atoms, wherein the three alkylene groups share a common carbon atom and, together with the N atom in the formula, form a tricyclic structure, and wherein at least one alkyene group has at least one OH group in an &agr; or &bgr; or &ggr; position relative to the N atom,
to obtain a monomer-containing polyisocyanurate mixture.
Another embodiment of the present invention provides a monomer-containing polyisocyanurate mixture, prepared by a process including:
partially trimerizing isophorone diisocyanate in the presence of a catalyst having the formula:
[R—NX
3
]
⊕
Y
⊖
wherein R and X are butyl groups and Y
−
is CH
3
COO
−
; or
wherein R is a benzyl group, Y
−
is a carboxylate anion having from 4 to 8 carbon atoms and each X is an alkylene group having from 2 to 3 carbon atoms, wherein the three alkylene groups share a common carbon atom and, together with the N atom in the formula, form a tricyclic structure, and wherein at least one alkyene group has at least one OH group in an &agr; or &bgr; or &ggr; position relative to the N atom.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Various other objects, features and attendant advantages of the present invention will be more fully appreciated as the same becomes better unde
Ewald Michael
Kohlstruk Stephan
Lomoelder Rainer
Degussa - AG
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Sergent Rabon
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