Bayer Aktiengesellschaft

Hans J Kreuder

Eckhard De Cleur

Rolf Dhein

Hans Rudolph

Rolf-Volker Meyer

Kuno Wagner

Hanns P Muller

Josef Pedain

Kurt Findeisen

Rudolf Merten

Hanns-Peter Muller

Walter Schafer

Ludwig Rottmaier

Eberhard Konig

Christian Wegner

Wolfgang Kremer

Theo Kempermann

Bernd Peltzer

Johannes Beckers

1,2,4-Triazole-blocked polyisocyanates are excellent crosslinking agents for polyhydroxyl compounds. Their comparatively high melting point makes these compositions particularly suitable for coatings which are applied by fluidisation dip coating or electrostatic powder spraying.

1,2,4-Triazole-blocked polyisocyanates as cross-linkers for lacquer

New amidine/isocyanate adducts are particularly useful as catalysts for hardening epoxy resins, in particular pulverulent coating compositions based on epoxy resins. New bicyclic amidines are excellent starting materials for manufacturing these amidine/isocyanate adducts.

Bicyclic amidine-isocyanate adducts

Tetrahydropyrimidine-isocyanate addition products

Bicyclic amidines

The present invention relates to lacquer polyisocyanates which contain about 0 to 8% free isocyanate groups, about 10 to 28% blocked isocyanate groups and about 2 to 10% of the structural units, --NH--NH--CO--O, all percentages based on the weight of the polyisocyanates, but excluding the weight of the blocking agent. Also provided is a process for preparing these polyisocyanates which comprises reacting about 10 to 30 mol % of the isocyanate groups of an organic polyisocyanate with reaction products which have (i) alcoholic hydroxyl groups and (ii) structural units of the formula, --O--CO--NH--NH--CO--O--, and/or of the formula H.sub.2 N--NH--CO--O--, with the formation of urethane groups and optionally groups corresponding to the formula, --NH--NH--CO--O--, and reacting about 50 to 90 mol % of the isocyanate groups of the organic polyisocyanate with a blocking agent. The reaction products containing alcoholic hydroxyl groups are obtained by reacting 1 mol of hydrazine or of hydrazine hydrate with about 1 to 2 mols of a cyclic carbonate. A final object of the present invention is the use of the new lacquer polyisocyanates as the isocyanate component in thermosetting, two-component polyurethane lacquers.

Lacquer polyisocyanates, process for the production thereof and use

A powder lacquer binder composition which comprises a homogeneous crosslinkable mixture comprising: (A) a polymer containing more than one carboxyl group and having a melting and softening point of from 20.degree. to 150.degree. C. (as determined by differential thermoanalysis) and an acid number of from 10 to 150 mg of KOH/g; and (B) a 1,2-polyepoxide which is N,N',N'-triglycidyl triazolidine-3,5-dione having an epoxide value of from 0.6 to 1.13; the mixture containing from 0.5 to 1.5 1,2-epoxide group per carboxyl group; and a process for the preparation thereof.

Power lacquer binders and process for the preparation thereof

Compounds having a melting point above 40.degree. C. which compounds contain uretone imine groups and which are substantially free from volatile isocyanate blocking agents which are split off under stoving conditions are excellent crosslinking agents for pulverulent coating compositions based on hydroxyl groups-containing polymers.

Pulverulent coating composition

The present invention relates to mixtures which are suitable for use as lacquer powders or as binders for lacquer powders and which are solid and capable of being pulverized at temperatures below about 40.degree. C. and liquid at temperatures above about 150.degree. C., which mixtures comprise

Pulverulent coating substance

Object of the invention are pulverulent coating compositions which are obtained if the coating compositions contain as crosslinking agents polyglycidyl esters of polycarboxylic acids and as binders polyesters from polyalcohols and predominantly aromatic polycarboxylic acids which contain free carboxyl groups.

Pulverulent coating agents

Alkyd resin lacquers which contain cellulose nitric acid esters can be prevented from 'lifting' and yellowing by the addition of bis-[hydroxyphenyl]-alkanes which are substituted in the nucleus.

Nitrocellulose alkyd resin lacquers containing

The invention relates to a pulverulent coating material prepared from a polyester which contains free carboxyl groups of succinic acid and cross-linking agents which react with carboxyl groups at elevated temperatures.

Growing community of inventors

Krefeld, Germany

Hans J Kreuder