Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Patent
1996-07-18
1998-10-06
Gorr, Rachel
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
528 60, 528 85, 524591, 4284231, 4274071, C08G 1830
Patent
active
058177337
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a water-dilutable polyurethane resin which is obtainable from (a) and has at least 1, preferably at least 2, and less than 3 hydroxyl and/or amino groups, isocyanate groups and at least one group capable of forming anions, which group is neutralized before or after the incorporation of component (d) into the polyurethane molecule, and groups, to prepare an intermediate which contains terminal isocyanate groups and at least some of whose free isocyanate groups have been reacted subsequently if desired with the component (e).
The present invention also relates to processes for the preparation of these polyurethane resins, to coating compositions which contain these polyurethane resins, to processes for the preparation of these coating compositions and to processes for the preparation of a multilayer protective and/or decorative coating on a substrate surface.
Because of ever stricter environmental regulations, the paint industry has made great efforts to reduce the organic solvents employed in coating compositions. Aqueous coating compositions have been developed which are increasingly displacing the conventional coating compositions, which contain exclusively organic solvents. In order to prepare these aqueous coating compositions it is common to employ water-dilutable binders dissolved in organic compounds. Polyurethane resins in particular have acquired a high degree of importance in this context. Even in the preparation of these water-dilutable polyurethane resin solutions in organic compounds, however, there is a demand for the polyurethane resin solution to have a minimal solvent content and a correspondingly high solids content. The demand is therefore for water-dilutable polyurethane resins, dissolved in organic compounds, which can be prepared with as high a solids content as possible.
For example, German Patent Application P 43 20 969.6, which is not a prior publication, discloses the preparation of polyurethane resins using ethoxyethyl propionate as solvent. The use of ethoxyethyl propionate in this context offers the advantage that, on the one hand, the polyurethane resins can be prepared without a stripping operation, and therefore in a cost-effective manner, and that, furthermore, the good viscosity-regulating properties of ethoxyethyl propionate and the good resistance at elevated temperatures mean that it is possible to prepare high-solids polyurethane resin solutions.
Further disclosures, for example in EP-A 438 090, relate to binder compositions for the preparation of pigment pastes and to aqueous coating compositions which contain these pigment pastes. These pigment pastes known from EP-A-438 090 contain from 20 to 50 parts by weight of a polyester-urethane resin which is obtainable by reacting a diisocyanate (A) with one or more polyesterpolyols (B), with low molecular weight diols (C) some of which have at least one acid group which is capable of forming anions, and--if desired--with low molecular weight triols (D). employ diols having sterically hindered primary hydroxyl groups, such as, for example, 2-ethyl-2-butyl-1,3-propanediol etc., to improve the hydrolysis resistance. However, EP-A-438 090 contains no information as to how very high-solids polyurethane resin solutions can be obtained.
The object of the present invention is consequently to provide water-dilutable polyurethane resins which have properties which are improved in relation to the prior art. Above all, the polyurethane resins should lead to aqueous coating compositions which, when used in basecoat/clearcoat procedures, give improved multicoat finishes.
In particular, the water-dilutable polyurethane resin solutions should be able to be prepared with as high a solids content as possible and should permit the preparation of aqueous coating compositions having a minimal content of organic solvents.
This object is surprisingly achieved by the polyurethane resins of the type indicated at the outset, which are characterized in that the component (a) which is employed comprises ##STR3## in whic
REFERENCES:
patent: 4701480 (1987-10-01), Markusch et al.
patent: 5545708 (1996-08-01), Onwunaka et al.
BASF Lacke & Farben AG
Gorr Rachel
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