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...
Reexamination Certificate
2002-07-12
2004-09-28
Gorr, Rachel (Department: 1711)
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...
C560S026000
Reexamination Certificate
active
06797771
ABSTRACT:
The present invention relates to novel aqueous compositions curable physically, thermally, or thermally and with actinic radiation, and comprising Theological aids based on urea urethanes. The present invention also relates to the use of the novel compositions to prepare novel aqueous coating materials, adhesives, and sealing compounds. The present invention additionally relates to novel processes for preparing novel aqueous coating materials, adhesives, and sealing compounds from aqueous or aqueous/organic compositions curable physically, thermally, or thermally and with actinic radiation and comprising rheological aids based on urea urethanes. The present invention further relates to novel coatings, adhesive films, and seals which are produced with the aid of the novel coating materials, adhesives, and sealing compounds and/or of the novel processes.
Thermally curable aqueous coating materials which comprise a crosslinking agent and an ionically and/or nonionically stabilized polyurethane which is saturated, unsaturated, and/or grafted with olefinically unsaturated compounds and is based on aliphatic, cycloaliphatic, aliphatic-cycloaliphatic, aromatic, aliphatic-aromatic and/or cycloaliphatic-aromatic polyisocyanates, and also the corresponding coatings, are known, for example, from the patents EP-A-0 089 497, DE-C-197 22 862, and DE-A-196 45 761. They are normally referred to as aqueous basecoat materials. The special rheological properties required for the storage and application of these known aqueous basecoat materials, such as viscosity, pseudoplasticity and thixotropy, are formulated through the use of an inorganic phyllosilicate of the montmorillonite type. Its use is necessary in order to give the aqueous basecoat material its familiarly good performance properties such as, for example, good atomizability, stability, and, in the case of effect aqueous basecoat materials, an excellent metallic effect, i.e., a very highly pronounced flip-flop effect. Furthermore, in preparing the known aqueous basecoat materials it is necessary to insert a homogenization step following the addition of each constituent, so making production comparatively complex.
Unfortunately, the inorganic phyllosilicates are unable to impart the desired Theological properties reliably at all times and under all circumstances. For instance, it may happen that the originally formulated viscosity of the aqueous basecoat materials provided with these phyllosilicates falls sharply on storage or on use at the customer's premises, thereby reducing the stability and deleteriously altering the metallic effect, in particular, in the aqueous basecoats in question.
The causes of this phenomenon, which may cause great problems in practice, are not yet fully understood. It is assumed that the phenomenon is related to the mechanism of rheology buildup in the monomorillonite, by way of dipoles within its molecular structure. Extremely damaging effects are exerted here by ionic materials and by materials which have strong electrical fields, examples being trivalent ferric ions, which have a particularly small ionic radius. Ferric ions of this kind are introduced into the aqueous basecoat materials by way, for example, of pigments. Surfactants and molecules with strong dipoles may also manifest themselves in an adverse manner.
Other Theological aids, such as thickeners based on polyurethanes or polyacrylates (cf. Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, N.Y., “thickeners”, pages 599 to 600), do not have these disadvantages. On the other hand, however, they have other disadvantages which prevent their use in the aqueous basecoat materials. These disadvantages include, in particular, a too weakly pronounced rheological effect and an absent thixotropic effect, and also insufficient stability, inadequate atomizability, and excessive sensitivity to a reduction in the pH of the aqueous basecoat materials in question.
A further disadvantage of the inorganic phyllosilicates is that they sometimes have adverse effects on the stability of aluminum effect pigments used in the aqueous basecoat material, with the consequence that they begin to gas if passivation is inadequate. In general, this can be remedied to a certain extent by chromating the surface of the aluminum effect pigments; however, chromating is not entirely unobjectionable from an environmental standpoint and is increasingly being shunned by users.
Another key disadvantage of the inorganic phyllosilicates is that they can be used exclusively in aqueous systems. The addition of sizable fractions of water-miscible organic solvents to aqueous basecoat materials prepared using said phyllosilicates causes streaking, phase separation, and flocculation. These adverse qualities make it impossible, for example, to use the customary and known, cost-effective dilute rinses to clean equipment and containers which have come into contact with the aqueous basecoat materials in question; instead, it is necessary to use special rinsing fluids such as mixtures of water, propanol, and butylene glycol.
A further disadvantage of the known aqueous basecoat material is that they have to be prepared in a plurality of stages, the sequence in which the constituents are incorporated being extremely critical for the success of the process. Moreover, it is frequently impossible to prepare concentrates having high solids contents, which is a disadvantage for storage and transportation.
Problems of rheology and thixotropy also occur, however, in pigment-free aqueous clearcoat materials.
Clearcoat materials are used to produce clearcoats and are frequently employed together with aqueous basecoat materials as part of the wet-on-wet process for producing multicoat color and/or effect coating systems on primed and unprimed substrates. In this process, as is known, basecoat films are applied to the substrates and are subsequently dried but not fully cured. The basecoat films are then overcoated with clearcoat films, after which both films are fully cured together.
Customary and known aqueous clearcoat materials are one-component (1K), two-component (2K) or multicomponent (3K, 4K) clearcoat materials curable thermally and/or with actinic radiation.
Aqueous one-component (1K) clearcoat materials comprise, in particular, hydroxyl-containing, water-soluble and/or water-dispersible binders, and also crosslinking agents such as blocked polyisocyanates, tris(alkoxycarbonylamino)triazine and/or amino resins.
Aqueous two-component (2K) and multicomponent (3K, 4K) clearcoat materials, as described, for example, in the European patent EP-A-0 654 052 (international patent application WO 94/03512), comprise—as is known—water-soluble and/or water-dispersible binders, containing isocyanate-reactive functional groups, especially hydroxyl groups, and also polyisocyanate crosslinking agents, the two components being stored separately from one another prior to their use.
Also known are siloxane clearcoat materials, which may be prepared by reacting hydrolyzable silicon compounds with water or water donors and which comprise organic constituents for the purpose of improving certain properties. Those materials are sold, for example, under the brand name ORMOCER® (organically modified ceramic). A general description of such systems can be found, for example, in the article by Bruce M. Novak, “Hybrid Nanocomposite Materials—Between Inorganic Glasses and Organic Polymers”, in Advanced Materials, 1993, 5, No. 6, pp. 422-433, or in the paper by R. Kasemann, H. Schmidt, 15
th
International Conference, International Centre for Coatings Technology, Paper 7, “Coatings for mechanical and chemical protection based on organic-inorganic sol-gel nanocomposites”, 1993.
In order to formulate the specifically desired rheological and thixotropic properties of the aqueous clearcoat materials, a large number of Theological aids are employed, examples being the polyurethane-based associative thickeners known from Römpp, op. cit., Georg Thieme Verlag, Stuttgart, New York, 1998, “thickeners”, pages 599 to 600,
Hupp Anne
Josten Karl-Heinz
Sapper Ekkehard
Schwarz Jörg
Vesper Willi
BASF Coatings AG
Gorr Rachel
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