Aminoazole-blocked isocyanate components

Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...

Reexamination Certificate

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C528S075000, C528S073000, C528S423000, C252S182220, C252S182200, C548S262400, C548S265400, C526S258000, C526S302000

Reexamination Certificate

active

06586552

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to aminoazole-blocked isocyanate components and to thermally curable compositions containing polyisocyanate components blocked with at least one aminoazole.
BACKGROUND OF THE INVENTION
Azole-blocked isocyanates, in particular polyisocyanates, are known, as shown in U.S. Pat. Nos. 4,976,837, 5,596,064, 5,889,106, 6,051,675 and EP-A-1 041 097. They may be used as crosslinking agents in thermally curable compositions based on binders with groups comprising active hydrogen, such as in particular binders comprising hydroxyl groups and/or primary and/or secondary amino groups. When heated, they eliminate the azole blocking agent to regenerate free isocyanate groups, which then react by addition with the binder groups comprising active hydrogen and are thus able to effect crosslinking.
Novel blocked isocyanate components have now been found which are thermally self crosslinkable and may be used in thermally self and/or externally crosslinkable compositions.
SUMMARY OF THE INVENTION
This invention provides isocyanate components blocked with at least one aminoazole, wherein the isocyanate components are selected from the group consisting of monoisocyanates with at least one olefinically unsaturated double bond per molecule and polyisocyanates.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Examples of aminoazole-blockable monoisocyanates with at least one olefinically unsaturated double bond per molecule are in particular free-radically homo- or copolymerisable monoisocyanates, such as, dimethyl-m-isopropenylbenzyl isocyanate or isocyanatoalkyl (meth)acrylates, such as, isocyanatoethyl (meth)acrylate.
Examples of aminoazole-blockable polyisocyanates are diisocyanates, such as, aliphatic, cycloaliphatic, aromatic or araliphatic diisocyanates, for example, hexane diisocyanate, trimethylhexane diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate, biscyclohexylmethane diisocyanate, norbornane diisocyanate, diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, tolylene diisocyanate, phenylene diisocyanate, naphthylene diisocyanate, xylylene diisocyanate as well as triisocyanates, such as, trisisocyanatononane.
Further examples of aminoazole-blockable polyisocyanates are oligomeric polyisocyanates derived from diisocyanates, for example from diisocyanates stated in the preceding paragraph, and having number average molecular masses in the range from for example 336 to 1000 and isocyanate contents of, for example, 8 to 25 wt. %, in particular, such polyisocyanate oligomers which contain heteroatoms in the residue linking the isocyanate groups. Examples of such substances are corresponding polyisocyanates comprising carbodiimide groups, allophanate groups, uretidione groups, isocyanurate groups, urethane groups and/or biuret groups. Particularly preferred compounds are uretidione polyisocyanates, biuret polyisocyanates, isocyanurate polyisocyanates or allophanate polyisocyanates each derived from hexane diisocyanate, uretidione polyisocyanates or isocyanurate polyisocyanates derived from isophorone diisocyanate and addition products of 3 mols of tolylene diisocyanate and 1 mol of triol, such as, trimethylolpropane.
Further aminoazole-blockable polyisocyanates are isocyanate-functional polymers having number average molecular masses of for example 800 to 10,000 and isocyanate contents of, for example, 2 to 27 wt. %. Processes for the production of such isocyanate-functional polymers are known to the person skilled in the art.
Production may, for example, proceed by free-radical homo- or copolymerisation of monoisocyanates with at least one olefinically unsaturated double bond per molecule.
Isocyanate-functional polymers may in particular also be produced by reacting simple polyisocyanates, for example above-stated simple diisocyanates or oligomeric polyisocyanates, in particular diisocyanates, with sub-stoichiometric quantities of organic compounds with at least two groups capable of reacting with isocyanate groups. Compounds of this kind that are preferably used are compounds comprising at least two primary and/or secondary amino groups and/or hydroxyl groups. Examples are low molecular weight polyols, polyamines and/or amino alcohols, such as, ethylene glycol, hexanediol, neopentyl glycol, butylethylpropanediol, cyclohexanedimethanol, trimethylolpropane, pentaerythritol, ethylenediamine, diethylenetriamine, ethanolamine, methylethanolamine, as well as oligomeric or polymeric compounds having a number average molecular mass of 300 to 5,000. Examples of the latter are polymeric polyols, for example, polyester polyols, polyethers polyols and/or hydroxy-functional acrylate resins known per se in polyurethane chemistry.
The blocked polyisocyanate components according to the invention are blocked with at least one aminoazole, wherein the single or various aminoazoles are in each case bound as a monofunctional blocking agent. For the purposes of the present invention, aminoazoles comprise 5-membered aromatic nitrogen heterocycles with a hydrogen-bearing nitrogen atom as one of the 5 ring members (azole nitrogen) together with a primary or secondary, preferably primary, amino group as an amino substituent on one of the C atoms of the azole ring. Depending upon the type of azole, further substituents may be present on the azole ring. Preferably, however, such further substituents may not contain active hydrogen. In particular, in addition to the directly bound amino substituents, the aminoazoles comprise no further hydroxyl or amino groups directly or indirectly bound to the aminoazole. The azole ring may also be a component of a fused ring system.
Examples of amino-substituted azole ring systems of the above-stated type are corresponding pyrrole, pyrazole, imidazole, 1,2,3- and 1,2,4-triazole, benzindazole and benzimidazole derivatives. The preferred blocking agent for the purposes of the present invention is 3-amino-1,2,4-triazole.
The isocyanate groups to be blocked of the polyisocyanate components are preferably exclusively blocked with at least one aminoazole. If desired, however, up to 80%, preferably no more than 50% of the isocyanate groups to be blocked may be blocked with other monofunctional blocking agents. Other blocking agents that may be considered alone or in combination are monofunctional compounds known for blocking isocyanates, such as, the CH-acidic, NH-, SH- or OH-functional compounds known for this purpose. Examples are CH-acidic compounds, such as, acetylacetone or CH-acidic esters, such as, acetoacetic acid alkyl esters, malonic acid dialkyl esters; aliphatic or cycloaliphatic alcohols, such as, n-butanol, 2-ethylhexanol, cyclohexanol; phenols; oximes, such as, methyl ethyl ketoxime, acetone oxime, cyclohexanone oxime; lactams, such as, caprolactam; azole blocking agents of the imidazole, pyrazole, triazole or tetrazole type hitherto known as blocking agents and which do not contain amino substituents.
While the production of aminoazole-blocked monoisocyanate components is trivial, blocked polyisocyanate components according to the invention may be produced by reacting the free isocyanate groups of the polyisocyanate components with at least one aminoazole, optionally, together with at least one further monofunctional blocking agent.
Where the polyisocyanate components are completely and exclusively blocked with aminoazole in an equivalent ratio of 1 mol of aminoazole per mol of isocyanate groups, it is expedient to add the polyisocyanate to the aminoazole, although the opposite mode of addition is also possible. The polyisocyanate and aminoazole are preferably brought into contact in the shortest possible time, wherein adequate cooling to abate the heat evolved during the exothermic blocking reaction should be provided. The reaction temperature should preferably not exceed 60° C., particularly preferably 50° C.
When producing co-blocked polyisocyanate components according to the invention, the polyisocyanate component is reacted with 0.2 to less than 1 mol of aminoazole and greater than 0 to 0.8 mol of at leas

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