Stock material or miscellaneous articles – Structurally defined web or sheet – Physical dimension specified
Patent
1987-03-11
1989-03-14
Jacobs, Lewis T.
Stock material or miscellaneous articles
Structurally defined web or sheet
Physical dimension specified
4273855, 4284231, 4284233, 4284237, 4284244, 4284246, 524710, 524773, 524871, 524872, B05D 302, B32B 2740, B32B 900, C08L 7504
Patent
active
048123560
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a coating composition for a flexible substrate, which hardens chemically on account of its content of isocyanate prepolymer or polyisocyanate. In particular the invention relates to a one-component coating composition of this kind, which in the ready-mixed state has a long shelf life if moisture is excluded, but after application to the substrate hardens by the action of moisture from the ambient atmosphere. The flexible substrates can be sheet materials, for example, which can be flexed or folded on account of their small thickness; sheet materials of this kind include, but are not limited to, metal foils, plastic films, artificial leather, paper, cardboard, roll roofing and the like. The substrates can also be hard and soft foams, and massive parts such as extrusions, pipes and other metal surfaces which are exposed to thermal expansion, as well as concrete surfaces.
The invention furthermore relates to a method for the production of a colored, highly elastic protective coating on a flexible substrate of the kind specified. Lastly, the invention relates to a variety of applications of this one-component, moisture-hardening coating composition.
Coating compositions for the production of a colored coating on a flexible substrate are known. The known coating compositions have a number of disadvantages. For example, one known coating composition has to be applied in about four coats to assure sufficient coverage. These great coating thicknesses are necessary because the basic binding agent does not permit high pigmentation, and therefore the desired shade of color can be obtained with sufficient covering power only in a plurality of coats. If the substrate is too severely bent or folded, the coating obtained from the known coating composition tends to crack and spall because the hardened coating is insufficiently elastic.
In the case of moisture-hardening one-component coating compositions containing polyisocyanate as binding agent, the elasticity of the hardened coating film might be improved by reducing the binding agent content and/or increasing the plasticizer content. In practical testing, however, difficulties arise with regard to curing, because if the polyisocyanate content is too low, the curing of the composition would require an exceedingly long period of time, on the one hand, and on the other hand the cure might be inadequate, so that the coating might be still sticky after a curing time of 10 hours and more.
Setting out from this knowledge, the present invention has the object of overcoming the above-described and other disadvantages of known coating compositions. In particular it is the object of the present invention to prepare a moisture-hardening one-component coating composition which will give a colored, light-resistant and highly elastic coating film which provides excellent adhesion to flexible substrates. Even in a coating thickness of only 50 micrometers good covering power is to be obtained, which will be capable of reliably protecting even delicate materials such as soft polyurethane foams against degradation by the action of visible light and/or ultraviolet light. The coating must furthermore be weather resistant and if necessary protect the substrate against mechanical damage.
The solution of this problem according to the invention is a moisture-hardening one-component coating composition for flexible substrates, which has the following composition: prepolymer and toluylene diisocyanate prepolymer in a ratio of from 54 to 68 parts by weight of the former to 32 to 46 percent by weight of the latter,
The coating composition according to the invention yields colored coatings after hardening which even in comparatively light coating thickness of only 50 micrometers give absolute coverage and have high resistance to light. The cured coating films have an unusually high elasticity, elongation and adherence to the substrate, so that a flexible substrate can be folded or creased without any tearing of a coating formed from the coating composition according to the
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patent: 3380950 (1968-04-01), Blomeyer
patent: 3919173 (1975-11-01), Coyner et al.
patent: 4131693 (1978-12-01), Wendt et al.
patent: 4375521 (1983-03-01), Arnold
patent: 4436784 (1984-03-01), Ehrhart
patent: 4567230 (1986-01-01), Meyer et al.
John Reinmar
Meyer Rainer-Leo
Muller Gunter
Nagel Rolf
BGB-Gesellschaft Reinmar John
Jacobs Lewis T.
Meyer Rainer-Leo
Meyer geb. Kloffer
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