Coating processes – With post-treatment of coating or coating material – Heating or drying
Patent
1993-09-27
1995-02-28
Green, Anthony
Coating processes
With post-treatment of coating or coating material
Heating or drying
4273837, 4273881, 4273884, 106 1405, 106 1411, 106 1413, 106 1414, 106 1421, 106 1441, 106 1444, 106 1445, C09D 508, C09D 510
Patent
active
053935675
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The invention relates to a powder mixture for making an anticorrosive zinc-containing undercoating agent for steel surfaces.
It is known to use zinc dust and/or zinc flakes as a corrosion-inhibiting pigment in organic undercoating agents. The undercoating agents consist essentially of a synthetic resin, which is dissolved in an organic solvent to produce a soft consistency during use. Aromatic hydrocarbons, like xylol, are primarily considered as organic solvents. The undercoating agent is stored in its liquid form in closed containers and is delivered in this manner. For a specified use it is directly applied to the previously cleaned steel surface. By evaporating the solvent, the mixture hardens and forms a solid closed layer in which the zinc dust is contained in a finely distributed form. When moist air penetrates into the undercoating, mainly basic zinc carbonate (4ZnO.multidot.CO.sub.2 .multidot.4H.sub.2 O) forms on the zinc flakes, which results during an increase in volume and an increase in the density of the undercoating and protects the steel surface lying therebelow from destruction. A further anticorrosive effect is due to the cathodic protective action of the zinc dust pigment.
Considerable amounts of organic solvents are emitted into the surrounding air during the application of the known zinc dust undercoating agents. The thus caused environmental damage has been accepted up to now because other binding agents, for example on a water base, did not appear to be suited because of the, to be expected, chemical reaction with the zinc powder.
Starting out from this, the basic purpose of the invention is to provide a one-component powder mixture to make an undercoating agent which can be environmentally friendly produced, stored and applied, and which has still good corrosion-inhibiting characteristics.
To attain this purpose the invention suggests to first produce a mixture of a dried, water-reemulsifiable powdery dispersion agent and a water-reactive zinc in a powder or flake form and which can be stored and transported in water-tight bags.
The mixture contains advantageously a water-reemulsifiable dispersion agent from the following groups: copolymer, a vinyl acetate-vinyl ester copolymer or a vinyl acetate-vinyl laurate-vinyl-versatate copolymer, an acrylate, an ethylene-vinyl laurate-vinyl chloride copolymer, a styrene copolymer, in particular a styrene acrylate or a styrene butadiene.
The mixture has furthermore advantageously a powdery filler or extender from the talcum, barium sulfate and mica group and/or a preferably organic pigment, which filler or extender is actually known in the lacquer industry. These materials help to improve the corrosion-inhibiting characteristics and to adjust the desired rheology.
In order to obtain during the application an easily homogenizable mixture out of the powdery parts with water, the use of actually known additives, like wetting agents, defoamers, thixotropic agents, agents promoting the film formation, is of an advantage.
The dry mixture of the invention contains advantageously the following parts: vinyl acetatevinyllaurate-vinyl-versatate-copolymer acrylate O), barium sulfate (BASO.sub.4) or mica (K.sub.2 O.multidot.3Al.sub.2 O.sub.3 .multidot.6SiO.sub.2 .multidot.2H.sub.2 O, or "PLASTORIT" types) promoting film formation, thixotropic agents.
The powdery dry mixture can be stored and transported in water-proof bags. Shortly before the application, 100 parts by weight of the powdery mixture is mixed by agitation with 5 to 50 parts by weight of water. After the water preferably 20 to 30 parts by weight of water, to form a viscous coating compound has evaporated, a closed continuous coating is formed. The good corrosion-inhibiting characteristics of the coating produced in this manner permit one to conclude that the zinc powder, which is reactive with water, is extensively shielded against the reaction with water by the water-absorbing dispersion agent during the short application time.
Exemplary embodiment 1
25 parts by weight of a po
REFERENCES:
patent: 3202517 (1965-08-01), Jarboe et al.
patent: 3849141 (1974-11-01), Palm et al.
patent: 3907608 (1975-09-01), Barrett et al.
patent: 3941609 (1976-03-01), Stern
patent: 3954510 (1976-05-01), Gunn et al.
patent: 4110117 (1978-08-01), McLeod
patent: 4370382 (1983-01-01), Salensky
patent: 4561896 (1985-12-01), Drake et al.
patent: 5167701 (1992-12-01), Savin
Herzog nee Kress Siglinde
Petrikat Axel
Wekenmann, deceased Guido
Green Anthony
Sika Chemie GmbH
LandOfFree
Powder mixture for making an undercoating agent for steel surfac does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Powder mixture for making an undercoating agent for steel surfac, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Powder mixture for making an undercoating agent for steel surfac will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-847257