Drying and gas or vapor contact with solids – Process – With nondrying treating of material
Patent
1993-04-30
1994-10-04
Hruskoci, Peter A.
Drying and gas or vapor contact with solids
Process
With nondrying treating of material
34406, 210710, 210737, 210770, 210774, 210930, 241 23, C02F 1120
Patent
active
053522508
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a process for working up (recycling) lacquer coagulum containing lacquer overspray and coagulant containing layer silicates, in which the lacquer coagulum containing layer silicates is dried in vacuo, treated at low temperatures and subsequently ground, and to the use of the lacquer coagulum thus worked up as a principal ingredient, additive or filler in lacquers and paints, building materials, sealing materials, undersealing compounds or adhesives.
STATEMENT OF RELATED ART
In the application of lacquers, waxes or similar coating materials containing water-insoluble organic substances to metal surfaces or plastic surfaces, for example in the automotive industry, the lacquers or coating materials cannot be completely applied to the parts to be coated. In the lacquering of motor vehicle bodies in particular, so-called overspray collects in the spray booths, being removed therefrom with water and flushed into a so-called "settling tank". In order, on the one hand, not to disrupt the function of water-carrying pipes, nozzles and sprinkler systems by tacky lacquer particles and, on the other hand, to remove the ingredients taken up from the circulating water, chemicals have to be added to the water to coagulate the substances mentioned. The chemicals added should detackify the sprayed lacquer particles taken up by the water and agglomerate them into a dischargeable coagulum in a single step.
In view of a growing environmental awareness, consideration has recently been given to me notion of using the lacquer coagulum collecting in industrial coating and lacquering plants as valuable raw materials in recycling strategies rather than disposing of them as waste. In addition, an amendment to the "Technische Anleitung Abfall (Technical Directive on Waste)" is about to be passed, banning the dumping and export of lacquer residues. The annual accumulation of lacquer residues is still put at around 250,000 t per year (VDI Nachrichten of Mar. 16, 1990), so that there is considerable useful material potential in the recycling of lacquer residues.
There has been no shortage of attempts to reduce the amount of overspray collecting by suitably designing the spray booths, to work up the lacquer sludges collecting via the spray booth water or to convert them into economically useful products. Thus. DE-A-32 27 227 describes a process, for recovering waterborne paint from the overspray collecting during lacquering with wet lacquers, which has been used for years in the electrophoretic processing of water-soluble electrophoretic lacquers. However, so-called solvent-containing lacquer waste cannot be worked up by this process.
The processing of lacquer sludges described in U.S. Pat. No. 4,303,559 essentially comprises grinding the sludge, drying the fragments obtained and regrinding the dried fragments. The particles obtained in this way may then be pressed and cured, for example to form sheets which may be used for insulation purposes.
In addition, DE-C-35 25 254 describes a process for reprocessing lacquer waste, in which the lacquer waste collected in crosslinkable form is convened into an aqueous dispersion by addition of suffactants, particularly anionic, cationic, nonionic or amphoteric surfactants, and application of mechanical forces. After curing under heat or pressure, the aqueous dispersions or emulsions obtained are used as vibrationdamping materials and as sound- and heat-insulating materials.
In addition, the above-cited article in VDI-Nachrichten describes the drying and utilization of lacquer coagulum by a "dry purge" concept which drives out hydrocarbens from the lacquer sludges without any emissions and converts the remaining resins into an odorless non-toxic powder. This powder has a calorific value of the order of 21,000 KJ/kg and may be used in cement kilns or heat generators.
Very recently, the lacquer residues purified by washing, particularly where the lacquer overspray is of one type only, have been freed from water in a kneader, made up with solvent and
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Geke Juergen
Huesemann Lutz
Rehm Hans-Joergen
Henkel Kommanditgesellschaft auf Aktien
Hruskoci Peter A.
Jaeschke Wayne C.
Ortiz Daniel S.
Wisdom, Jr. Norvell E.
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