Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1991-10-29
1993-05-18
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525157, 525569, 525513, 525519, C08L 2902, C08L 6126, C08L 2916
Patent
active
052122425
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a coating composition containing polymers, prepared by copolymerization of ethylenically unsaturated monomers which are in part hydroxyalkyl esters of .alpha.,.beta.-ethylenically unsaturated carboxylic acids and suitable auxiliaries and additives, optionally pigments, optionally fillers, organic solvent and an acid catalyst.
The present invention furthermore relates to processes for the preparation of this coating composition and the use of this coating composition for automobile repair finishing and as a stoving paint.
The crosslinking of paint films containing as the crosslinking component highly etherified melamine resins or other highly etherified amino resins and, as coreactant for these resins, hydroxyl-containing binders, has the disadvantage that this process is only operable at elevated temperatures.
For many applications it is undesirable to use high temperatures in the crosslinking process. This is true in particular for the field of automobile repair finishing. The use of polyisocyanates which leads to a reduction of the necessary crosslinking temperature is disadvantageous due to the toxicity of the polyisocyanates.
Furthermore it is known to use acid catalysts for the systems based on amino resin and hydroxyl-containing binder, in order thereby to reduce the stoving temperatures.
EP-B-64,338 discloses a coating composition based on hydroxyl-containing linear addition polymers and an essentially completely alkylated melamine-formaldehyde crosslinking agent, the acid catalyst used being a mixture of alkylated arylsulfonic acids. The mixture contains variously alkylated arylsulfonic acids.
EP-A-158,161 likewise discloses acid-curing coating compositions which in addition to melamineformaldehyde crosslinking agents also contain as binders hydroxyl-containing branched acrylate copolymers. Acid catalysts used are preferably sulfonic acid compounds or mixtures of different catalysts. Coating compositions which are fast curing at room temperature are obtained when the catalysts used are the mixtures of variously alkylated arylsulfonic acids disclosed in EP-B-64,338, but these coating compositions are significantly deficient with regard to the duration of the processibility of the coating compositions at room temperature (pot life). About 2 h after mixing the individual components of the coating composition, the viscosity of the system has already increased to twice the initial viscosity so that processing of the coating compositions is no longer possible or only possible with technical disadvantages. With these systems the haze of the resulting coatings is also in need of improvement.
The object of the present invention was therefore to provide coating compositions based on hydroxyl-containing addition polymers and amino resin crosslinking agents, which are fast curing at low temperatures, in particular at room temperature, but at the same time have as long a pot life as possible (at least about 4 h). The resulting coatings should moreover have as low a haze as possible and should have good hardness and good solvent resistance.
This object is surprisingly achieved by a coating composition containing polymers, prepared by copolymerization of ethylenically unsaturated monomers which are in part hydroxyalkyl esters of .alpha.,.beta.-ethylenically unsaturated carboxylic acids and suitable auxiliaries and additives, optionally pigments, optionally fillers, organic solvent and an acid catalyst.
This coating composition is one wherein the acid catalysts used comprise least one hydroxyl group and correspond to the following formulae (I) or (II): ##STR1## in which: R.sup.1 =a linear or branched alkyl or alkoxyalkyl radical having 2 to 12 carbon atoms and having 1, 2 or 3 hydroxyl groups carbon atoms and, if desired, up to 3 hydroxyl groups different, or an aliphatic or aromatic N-heterocycle least one hydroxyl group.
The present invention furthermore relates to a process for the preparation of these coating compositions and their use as an automobile repair finish or as a stoving pai
Gross Lutz-Werner
Jung Werner-Alfons
Wieditz Stefan
BASF Lache+Farben Aktiengesellschaft
Clark W. R. M.
Sabourin Anne Gerry
Seidleck James J.
Werner Frank G.
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