Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1992-12-15
1994-05-17
Welsh, Maurice J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524839, 524840, 528 71, 528 80, 528 81, C08L 7504
Patent
active
053128656
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to coating compositions containing aqueous polyurethane dispersions, the polyurethanes on which the polyurethane dispersions are based being synthesized from a polyol mixture which consists at least predominantly of polycaprolactone diols, and to the use of the coating compositions for the production of coatings on flexible substrates, preferably on leather, leather substitutes and/or flexible plastics.
BACKGROUND OF THE INVENTION
Coating compositions based on aqueous polyurethane dispersions have been known for some time. In general, the polyurethanes on which the polyurethane dispersions are based are produced by polyaddition of polyols with diisocyanates, the co-condensation of components capable of salt formation having an advantageous effect on dispersibility. Polyurethane urea dispersions, which are also used as coating compositions, are formed in the presence of chain-extending agents, such as diamines.
RELATED ART
European patent 148 970 describes stable aqueous dispersions of polyurethane ureas which may be used inter alia as coating compositions and impregnating agents for all types of substrates, as binders in paints, as adhesives and as auxiliaries in the paper industry. The polyurethane ureas on which the dispersions are based contain as internal emulsifier chemically incorporated anionic groups and a mixture of volatile and non-volatile cations as counterions. The resistance of the films to swelling under the effect of water is increased through the contents of volatile cations while the stability of the films to hydrolysis is increased through the content of non-volatile cations.
Polyurethane urea dispersions containing a co-condensed internal emulsifier are also known from DE-OS 26 24 442. The aqueous polyurethane urea dispersions described therein are used in DE-OS 36 25 605 for the production of aqueous pigment preparations for water-based and, optionally, alcoholic gravure, flexographic and screen printing inks. The pigment preparations obtained are relatively stable to alcohols and to storage and show improved adhesion properties and drying rates.
DE-OS 37 02 615 describes coating compositions and finishes for leather based on aqueous polyurethane dispersions. The polyurethanes on which the polyurethane dispersions are based are obtained using a polyol mixture consisting of polyester polyols and, optionally, polyether polyols and the compulsorily present oleochemical polyols containing at least three functional hydroxyl groups. The leathers or leather substitutes coated and finished with these polyurethane dispersions are entirely satisfactory in such properties as durability, brittleness, wet and dry rubbing resistance, compactness and gloss. In addition, they have high fastness values without the toxicologically unsafe aziridines having to be used for crosslinking, so that they are particularly suitable as top coats.
Although the above-described coating compositions based on aqueous polyurethane dispersions are improved in their properties, it has been preferred until very recently, for example in the leather industry for finishing leather, to apply polyurethanes to leather and leather substitutes from organic solution. In the field of printing inks, too, the consumption of solvent-containing inks is still considerably higher in relation to the consumption of water-based inks in which water is the sole liquid component or the principal liquid component besides alcohols.
Accordingly, there is still a need to improve coating compositions based on aqueous polyurethane dispersions in their properties, above all in their adhesion, hardness, resistance to water and alcohols, drying behavior and their wetting of the substrate, so that they may be used to the same extent as solvent-containing polyurethane systems.
Accordingly, the problem addressed by the present invention was to provide coating compositions based on aqueous polyurethane dispersions which are improved in their resistance to alcohols, their adhesion and the other properties
REFERENCES:
patent: 4098743 (1978-07-01), Scriven et al.
patent: 4124552 (1978-11-01), Koleske et al.
patent: 4171391 (1979-10-01), Parker
patent: 4203883 (1980-05-01), Hangauer, Jr.
Gruetzmacher Roland
Hoefer Rainer
Kaindl Gerhard
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Ortiz Daniel S.
Szoke Ernest G.
Welsh Maurice J.
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