Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Ethylenically unsaturated reactant admixed with either...
Patent
1993-02-25
1994-08-09
Marquis, Melvyn J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Ethylenically unsaturated reactant admixed with either...
525 30, 525920, 525921, 525922, 427421, C08L 6706
Patent
active
053367162
DESCRIPTION:
BRIEF SUMMARY
The invention relates to paints comprising .alpha.,.beta.-unsaturated carbonyl groups or a mixture of such resins, and/or carbonyl groups or a mixture of such crosslinking agents and .alpha.,.beta.-unsaturated carbonyl groups or a mixture of such catalysts.
The invention also relates to the use of these paints for the finishing of automobile bodies.
Paints of the type described above are known (cf. DE-OS-3,843,323 and Farbe+Lack, 95 (1989) page 71). They crosslink by the addition of hydroxyl groups onto activated carbon double bonds. According to DE-OS-3,843,323 and the Farbe+Lack paper, the addition of hydroxyl groups onto activated carbon double bonds is catalyzed by basic catalysts.
The object of the present invention is to provide novel paints of the type described above which are an improvement over those of prior art. The novel paints should in particular furnish crosslinked paint films which possess good solvent resistance and good weather resistance even when energy-saving baking conditions (low baking temperatures and/or short baking times) are used.
Surprisingly, this object is achieved by the preparation of paints of the type described above which contain as the catalyst (D) a Bronsted acid or a mixture of Bronsted acids.
Compared with paints which cure in the presence of basic catalysts, the paints according to the invention are distinguished by the fact that they furnish at comparable baking times already at lower baking temperatures crosslinked paint films which possess good solvent resistance and good water resistance. Compared with paints containing basic catalysts, the advantageous paint characteristics may be achieved, surprisingly, using smaller amounts of catalyst. A further advantage of the paints according to the invention lies in the fact that they may also comprise as crosslinking agents, in addition to the crosslinking agent (C) containing .alpha.,.beta.-unsaturated carbonyl groups, amino resins which can crosslink under conditions of acid catalysts with resins containing hydroxyl groups.
The paints according to the invention may be both organic solvent borne and aqueous.
In principle, any resin which contains both hydroxyl groups and .alpha.,.beta.-unsaturated carbonyl groups and which can be used as paint binder, may be employed as the resin (A). Examples of these are polyacrylate, polyester, alkyd, urethane, polyether and epoxy resins containing both hydroxyl groups and .alpha.,.beta.-unsaturated carbonyl groups. The resins may be prepared by known methods. Water-thinnable resins may be prepared by incorporating solubilizing groups (for example carboxylate groups) into the resin molecules. The number average molecular weight of the resins should expediently be between 250 and 100,000, preferably between 500 and 20,000, the .alpha.,.beta.-unsaturated carbonyl group content should be between 0.01 and 20, preferably between 0.1 and 5, mol per kg of resin and the hydroxyl group content should be between 0.01 and 50 mol, preferably between 0.1 and 10 mol per kg of resin.
.alpha.,.beta.-Unsaturated carbonyl groups have the formula ##STR1## and may be, for example, acryloyl, methacryloyl, itaconoyl, maleoyl, fumaroyl, crotonoyl, cinnamoyl, acrylamido or methacrylamido groups. The hydroxyl groups should preferably be primary hydroxyl groups.
A reaction product obtained from 1 mol of N-methylolacrylamide or 1 mol of N-methylolmethacrylamide, 1 mol of a diisocyanate and a hydroxyl-containing resin is preferably used as the resin (A). Resins of this type and the preparation of these resins are described in DE-OS-3,843,323.
In principle, any hydroxyl-containing resin suitable for the preparation of paints, which contains on statistical average at least two hydroxyl groups per resin molecule, may be used as the hydroxyl-containing resin (B). Examples of these are hydroxyl-containing polyacrylate, polyester, alkyd, urethane, polyether and epoxy resins.
The resins can be prepared by known methods. Water-thinnable resins may be prepared by incorporating solubilizing groups (for example carboxyl
REFERENCES:
patent: 3558563 (1971-01-01), Cunningham
Kappes Elisabeth
Poth Ulrich
Aylward D.
BASF Lacke & Farben Aktiengesellschaft
Marquis Melvyn J.
Sabourin Anne Gerry
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