Flow controllers for powder lacquers

Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From heterocyclic reactant containing as ring atoms oxygen,...

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Details

528408, 528271, 525410, 525540, C08G 5900

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active

057863083

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to flow controllers for powder lacquers containing polymers with oxazoline and/or oxazine monomer units and to processes for their production.


BACKGROUND OF THE INVENTION

Low-solvent or solvent-free coating systems are acquiring increasing significance. This group of coating systems includes powder coating, i.e. the coating of metals and plastics by application and sintering of heat-curing powders. They may be applied by rotational coating, powder spraying, fluidized-bed coating and, above all, by electrostatic coating. Thermoset powder lacquers of epoxy, polyester and acrylic resins are particularly suitable for electrostatic powder coating. Thermoplastics of polyamide, polyester, polyethylene, polyethylene vinyl acetate, polyvinyl chloride and polyepoxides are preferably used for fluidized-bed coating. Powder coating is used above all for machine parts and domestic goods (for example steel furniture). To promote the flow of the polymer powder during stoving or sintering, flow controllers are added so that any irregularities formed during application, such as streaks, bubbles, craters, orange peel structures and pinholes, are largely eliminated. Known flow controllers include acrylate copolymers. These are generally liquid polyacrylate-based products, for example the commercial products Perenol.RTM. F 40, Perenol.RTM. F 30 P mod (Henkel KGaA) or Modaflow.RTM. (Monsanto), which basically may be incorporated in the powder lacquers by two different methods: controller into a binder component of the powder lacquer. The solidified melt is then size-reduced and made up for subsequent processing.
The disadvantage of master batch technology is that the formulation of powder lacquers is limited because the binder of the master batch has to be identical or at least compatible with the principal binder of the formulation.
Flow controllers applied to a carrier can lead to a reduction in the gloss of the lacquer and to a reduction in the transparency of clear lacquers and, under adverse conditions, to a deterioration in the storage stability of the powder lacquer on account of the incompatibility of the generally inorganic carrier with the lacquer film.


RELATED ART

In addition, either method gives solid flow controllers containing 100% by weight of active substance. To eliminate these disadvantages, powder-form flow controllers based on polyacrylates have been developed, more particularly for the production of clear lacquers, requiring neither an inert carrier nor a master batch process. One such flow controller is described, for example, in EP-A1 0 355 676. The disadvantage of these solid polyacrylates is that the improvement in flow obtainable with small quantities is inadequate and, although satisfactory flow properties are obtained where larger quantities are used, the resulting films are cloudy.
In addition, the softening temperatures are still so low that the flow controllers can become lumpy after prolonged storage.
Polyoxazolines are known compounds which are obtained in the polymerization of oxazolines substituted in the 2-position. The production of oxazolines substituted by long-chain alkyl groups is described, for example, in EP-A1 315 858. The cationic polymerization of oxazolines is comprehensively described, for example, by S. Kobayashi and T. Saegusa in the monograph "Ring Opening Polymerization", Ed. K. J. Ivin, T. Saegusa, Vol. 2, pages 761-790, London, Elsevier, 1984.
5,6-Dihydro4H-1,3-oxazines substituted in the 2-position, hereinafter referred to as oxazines, are also known compounds of which the synthesis is described, for example, in DE-A1 39 14 155. The polymerization of the oxazines is described in the monograph cited above (pages 791-795).
The copolymerization of oxazolines and oxazines is also known.
Polyoxazolines are produced by living cationic polymerization. It is known that this polymerization can be carried out in standard reactors, for example glass vessels or stirred tank reactors, in the presence of suitable solvents or in the abs

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"Ring Opening Polymerization", Ed. K.J.Ivin, T.Segusa, vol. 2, , London, Elsvier, 1984, pp. 761-790.
Cyclic 1,3-Oxaza Compounds, S. Kobayashi and T. Saegusa, Department of Synthetic Chemistry, Chapter 11, pp. 761-791.

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