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
2000-05-25
2002-01-29
Niland, Patrick D. (Department: 1714)
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...
C252S182200, C252S182220, C252S182240, C252S182260, C524S507000, C524S539000, C524S589000, C524S590000, C525S123000, C525S127000, C525S440030, C525S453000, C525S455000, C528S044000, C528S060000, C528S065000, C528S059000, C528S085000, C564S123000, C564S152000, C564S153000, C564S160000, C564S163000, C564S167000
Reexamination Certificate
active
06342576
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to urethanized &bgr;-hydroxyalkylamide compounds, to a process for preparing them, to their use for preparing highly reactive powder coating materials, and to the powder coating materials themselves.
2. Description of the Background
Powder coating materials based on triglycidyl isocyanurate (TGIC) and acid functional polyesters give corrosion-resistant and weather-stable powder coatings. EP 0 536 085 describes, however, how the preparation of TGIC in solid form necessitates expensive processes or a relatively great, and therefore likewise expensive, purification effort. Moreover, TGIC is classified by the European Community as a category II mutagen (to be regarded as inducing heritable genetic defects) and as of May 31, 1998 has had to be labeled as toxic.
Toxicologically acceptable crosslinkers which are also more reactive include hydroxyalkylamides. In patents U.S. Pat. Nos. 4,076,917 and 4,101,606, the hydroxyalkylamides are combined with polymers having at least one carboxyl or anhydride function, in particular with polyacrylates, to form powder coating materials. EP 0 322 834 describes heat-curing powder coating materials which are composed of polyesters containing acid groups and of &bgr;-hydroxyalkylamides. These coatings with &bgr;-hydroxyalkylamide crosslinkers are highly weather-stable, very flexible, hard and chemical-resistant. For numerous applications, such as in the sanitation industry or in the coating of laboratory equipment, the chemical resistance is not, however, sufficient.
It was therefore the object of the present invention to find novel crosslinkers which in combination with carboxyl-containing polymers can be processed to powder coating materials which give coatings extremely resistant to chemicals.
SUMMARY OF THE INVENTION
It has surprisingly been found that urethanized &bgr;-hydroxyalkylamide compounds constitute outstanding crosslinkers and, in combination with acidic polymers in powder coating materials, bring about a massively increased chemical resistance without detriment to the flexibility, hardness, reactivity, or weathering stability.
The present invention therefore provides urethanized &bgr;-hydroxyalkylamide compounds synthesized from the components
A) from 65 to 96% by weight of &bgr;-hydroxyalkylamide and
B) from 4 to 35% by weight of a nonaromatic polyisocyanate having an NCO functionality≧2,
the urethanized &bgr;-hydroxyalkylamide compounds carrying hydroxyl groups terminally and having a functionality≧2.
DETAILED DESCRIPTION OF THE INVENTION
The invention preferably provides urethanized &bgr;-hydroxyalkylamide compounds wherein the &bgr;-hydroxyalkylamide A) has the formula
in which R
1
is hydrogen or a C
1
-C
5
alkyl group, R
2
is hydrogen, a C
1
-C
5
alkyl group or
wherein R
1
is as defined above, and A is a chemical bond or, a monovalent or polyvalent organic group selected from saturated, unsaturated and aromatic hydrocarbon groups, and substituted hydrocarbon groups, having 2 to 20 carbon atoms, m is 1 or 2, n is from 0 to 2 and m+n is at least 2.
With particular preference, these compounds of the invention have a functionality of four or more.
The invention further provides for the use of the urethanized &bgr;-hydroxyalkylamide compounds to prepare transparent or pigmented, outdoor-resistant powder coating materials having high reactivity and hardness, excellent gloss and very good chemical resistance, prepared from the urethanized &bgr;-hydroxyalkylamide compound and carboxyl-containing polymers and also from the adjuvants customary in the chemistry of powder coatings, such as pigments, fillers, leveling agents, devolatilizers, catalysts if desired, and other additives, for example.
The invention also provides transparent and pigmented powder coating materials comprising the urethanized &bgr;-hydroxyalkylamide compounds of the invention.
The &bgr;-hydroxyalkylamides A) are known in principle and are described, for example, in U.S. Pat. Nos. 4,076,917; 4,101,606; EP 0 322 834 and EP 0 473 380. The structure can be described as follows:
in which R
1
is hydrogen or C
1
-C
5
alkyl, R
2
is hydrogen, C
1
-C
5
alkyl or
where R
1
is as defined above, and A is a chemical bond or a monovalent or polyvalent organic group derived from saturated, unsaturated or aromatic hydrocarbon groups, including substituted hydrocarbon groups of 2 to 20 carbon atoms, m is 1 or 2, n is from 0 to 2 and m+n is at least 2.
The nonaromatic polyisocyanate B) having an NCO functionality≧2 can be any aliphatic, (cyclo)aliphatic, cycloaliphatic or heterocyclic polyisocyanate having at least two isocyanate groups, or a mixture thereof. Polyisocyanates of this kind are mentioned, for example, in Houben-Weyl, Methoden der Organischen Chemie, Volume 14/2, page 61 ff. and in J. Liebigs Annalen der Chemie, Volume 562, pages 75 to 136. Representative examples of the polyisocyanates are aliphatic isocyanates such as alkylene isocyanates, e.g., ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 2-methylpentamethylene 1,5-diisocyanate (MPDI), hexamethylene diisocyanate (HDI), trimethylhexamethylene 1,6-diisocyanate (TMDI), especially the 2,2,4 and the 2,4,4 isomer, and technical-grade mixtures of both isomers, decamethylene diisocyanate and dodecamethylene diisocyanate, and also cycloalkylene isocyanates, e.g. 1,3-cyclopentyl diisocyanate, 1,2-cyclohexyl diisocyanate, 1,4-cyclohexyl diisocyanate, &ohgr;,&ohgr;′-diisocyanato-1,4-methylcyclohexane, &ohgr;,&ohgr;′-diisocyanato-1,3-dimethylcyclohexane, 1-methyl-2,4-diisocyanatocyclohexane, 4,4′-methylenebis(cyclohexyl isocyanate), norbornane diisocyanate (NBDI) and 3,3,5-trimethyl-1-isocyanato-3-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI). Advantageous polyisocyanates are those obtainable by reacting polyisocyanates with themselves via isocyanate groups; especially isocyanurates, which come about through the reaction of three isocyanate groups. Mixtures of diisocyanates and isocyanurates, especially of 2-methylpentamethylene 1,5-diisocyanate, 2,2,4-trimethylhexamethylene 1,6-diisocyanate, 2,4,4-trimethylhexamethylene 1,6-diisocyanate, norbomane diisocyanate, isophorone diisocyanate, the isocyanurate of 2-methylpentamethylene 1,5-diisocyanate, the isocyanurate of hexamethylene diisocyanate or the isocyanurate of isophorone diisocyanate, are particularly advantageous. The polyisocyanates may likewise include biuret groups or allophanate groups.
The invention additionally provides a process for preparing urethanized hydroxyalkylamide compounds, which comprises reacting from 65 to 96% by weight of at least one &bgr;-hydroxyalkylamide A) with from 4 to 35% by weight of at least one nonaromatic polyisocyanate B), the urethanized &bgr;-hydroxyalkylamide compounds carrying hydroxyl groups terminally and having a functionality≧2.
The urethanized &bgr;-hydroxyalkylamide compounds of the invention can be prepared in a solvent. Preferably, however, they are prepared in bulk—that is, without solvent. For this purpose, the &bgr;-hydroxyalkylamide A) is introduced initially and the polyisocyanate B) is added. The reaction can be monitored by determining the NCO number and is over after from 30 minutes to 3 hours. Known methods and technologies are used for cooling, comminuting and bagging.
The present invention further provides for the use of the urethanized &bgr;-hydroxyalkylamide compounds of the invention to prepare transparent or pigmented weathering-resistant powder coating materials of high reactivity and hardness and excellent gloss.
The invention additionally provides transparent or pigmented powder coating materials which comprise the urethanized &bgr;-hydroxyalkylamide compounds of the invention and carboxyl-containing polymers and also the adjuvants customary in the chemistry of powder coatings, such as pigments, fillers, leveling agents, devolatilizers, catalysts if desired, and other additives, for example. In comparison to &bgr;-h
Degussa-Huels AG
Niland Patrick D.
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