Compositions: coating or plastic – Coating or plastic compositions – Coating repellent
Patent
1992-05-26
1994-07-19
Green, Anthony
Compositions: coating or plastic
Coating or plastic compositions
Coating repellent
210698, 210728, 210729, 210930, 252DIG8, 134 38, C09D 520
Patent
active
053305647
DESCRIPTION:
BRIEF SUMMARY
The invention relates to aqueous and storage-stable compositions for the deposition of a subsequently-removable barrier layer upon internal surfaces of spray-coating booths and the like, and a process for their production.
During painting processes carried out in spray-coating booths, surfaces inside the booth--particularly floors, gratings, pipes and other equipment--are liable to become coated in excess paint. To facilitate the removal of these unwanted paint layers, it is common practice to pre-coat the surfaces which may be affected with protective coatings or barrier layers, which are relatively easily removable. These protective coating layers and paint layers have previously been removed by washing down with warm or hot water, by dissolution with solvents, or by mechanical treatment. Besides the ability easily to be removed, further requirements of the protective coatings are that they are not coloured, and do not absorb light but are instead reflective.
U.S. Pat. No. 2,563,499 describes a protective coating which, together with the adhering paint-spray, can be removed with only warm or hot water. The protective coating was produced from an aqueous suspension of a colouring pigment and a colloidal clay together with an emulsion of a paraffin wax. Oleic acid/triethanolamine or mixed polyether-sorbitan monopalmitate was used as the emulsifier.
U.S. Pat. No. 3,476,575 describes a protective coating which consists of an aqueous emulsion of a terpenehydrocarbon polymer, an oil, wax, a fatty-acid salt as the emulsifier, and a colouring pigment. In addition, it can also contain other usual additives, as well as fillers, thickening agents, preservatives and antioxidants. This protective coating can also be removed optimally with only hot water or steam.
The use of solvents, oils and waxes in coating compounds can lead to severe impairment of the coagulation effect following their disposal in the water circulating in the coagulation section. Large amounts of these solvents are not collected, but instead enter the water circulating in the coagulation streams. In addition, the use of emulsifiers can lead to foam formation.
The basic aim of the invention is to prepare a storage-stable protective coating composition which after use is easy to remove from treated surfaces with cold water, and which is free from solvents and oil and does not contain emulsifiers. The components of the formulation should not lead to emulsion formation with paint constituents to cause a separate effluent problem, for example de-emulsification. The aim is also to be achieved by using ecologically, toxicologically, and particularly aquatically safe formulations, and biodegradable substances.
According to the invention there are provided aqueous, storage-stable compositions for the deposition of temporary barrier layers on spray-coating booths and the like, which compositions contain metal salt thereof, amine and/or alkali metal hydroxide, and and/or carboxymethylcellulose,
The preferred carboxylic acid is 2-ethyl-hexanoic acid, which is preferably used in a proportion of from 10 to 25% by weight. The sodium or potassium salts of this acid may also be used, either alone or in mixture with the acid.
As the pH-regulator, monoethanolamine and/or triethanolamine are preferably used, either alone or in mixture with sodium hydroxide or potassium hydroxide. Alkanolamine-free formulations are equally possible when the pH value is controlled by an alkali metal hydroxide.
Layered silicates are used as a thixotropic and/or thickening agent. Bentonites, hectorites, laponites or saponites are preferred for this purpose. Alternatively, polyacrylates and/or carboxymethylcellulose can be used in place of, or in mixture with, the layered silicates. These components are preferably used in a proportion of from 3 to 8% by weight.
The pH values of the total formulations lie between pH 6 and 10, preferably between pH 7 and 8; their viscosity values (according to DIN 53 211) lie between 30 and 50 DIN-sec, but preferably between 35 and 40 DIN-sec.
Apart from t
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Bruegel Emil
Buick Kurt
Fehr Hans
Geke Juergen
Huesemann Lutz
Green Anthony
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Szoke Ernest G.
Wisdom, Jr. Norvell E.
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