Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1993-03-18
1995-04-18
Lusignan, Michael
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
427284, 427285, 427393, 428481, 428526, 428530, 525443, C08L 5100, C08L 6700
Patent
active
054079950
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to aqueous coating compositions, in particular for the coating of veneer films and continuous edges, containing a coating component I, which comprises
A) one or more water-dilutable melamine and/or urea resins,
B) one or more hydroxyl-containing polyesters and
C) if desired, pigments and/or fillers and, if desired, customary auxiliaries and additives and
D) if desired, diluents,
The invention also relates to processes for the coating of veneer films and continuous edges, using these aqueous coating compositions.
Impregnated papers which, when pressed onto boards, represent a preparative treatment in terms of priming (base film) or often also have a decorative effect (decorative film), have been well established in the furniture and board-making industry for a long time. After being pressed onto chipboards or hardboards, the films must be overcoated.
This additional operating procedure is unnecessary when a veneer film is used which is already coated by the film producer, following impregnation. The veneer films and continuous edges (for the continuous coating of edges) thus obtained are delivered to the furniture and board-making industry in the form of rolls, where they are glued onto substrates, such as, for example, chipboards or hardboards, by applying heat and/or pressure. This gives surfaces which usually do not need to be further coated, i.e. can be further processed as pressed.
German Offenlegungsschrift 2,316,158 has disclosed aqueous acid-curing two-component coatings based on etherified amino resins and polyester resins, which are also used for the coating of films for the furniture industry. In these two-component coatings, linear and/or branched polyesters having a molecular weight between 200 and 6000 and an OH number of up to 450 mg of KOH/g are used. These polyesters are prepared in the usual manner by reacting conventional dicarboxylic acids with conventional alcohols carrying two or more hydroxyl groups.
The coating agents described in German Offenlegungsschrift 2,316,158 are distinguished by rapid curing and high hardness, scratch resistance and stackability of the resulting coating, but have the disadvantage of a high formaldehyde emission of veneer films and continuous edges coated with these coatings. However, since the legal requirements with respect to formaldehyde emission of veneer films used in the furniture industry become ever more stringent, there is a very high demand for veneer films having less formaldehyde emission. Another disadvantage is the high plasticizer content of these coating agents, which is necessary for achieving good adhesion of the paints on the film and which can also lead to emissions under the drying conditions customary in practice or to slow emission from the paint film.
The development of special, water-repellant pore-leaving printing inks also makes available veneer films having a three-dimensional pore structure, which constitute an excellent imitation of a wood veneer (cf., for example, German Offenlegungsschrift 3,247,677, German Offenlegungsschrift 3,314,610 and German Offenlegungsschrift 3,024,391).
These veneer films having a three-dimensional pore structure are prepared by coating the films printed with the water-repellant pore-leaving printing ink with an aqueous acid-curing paint which, apart from a melamine resin, also contains a water-dilutable polyester resin or an acrylate resin or an ethoxylated glycerol derivative. However, these aqueous coating agents too have the disadvantage that, apart from solvents and water, other coating components, such as plasticizers, polyols or degradation products thereof, are also emitted under the drying conditions customary in practice.
Moreover, the impregnated and coated decorative papers described in the examples of German Offenlegungsschrift 3,314,610 have an excessively high formaldehyde emission of more than 3.5 mg/hm.sup.2, determined according to DIN 52 368. Finally, the decorative papers coated with these coating agents have only insufficient resistance to household c
REFERENCES:
patent: 4208488 (1980-06-01), Kraft et al.
patent: 4331717 (1982-05-01), Wenzel et al.
Hintze-Bruning Horst
Roll Joachim
BASF Lacke & Farben Aktiengesellschaft
Lusignan Michael
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