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
1993-12-27
1998-06-02
Seidleck, James 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...
4274071, 427409, 4273884, 524839, 524840, 528 44, 528 45, 528 80, 528 84, C08K 320
Patent
active
057601283
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for the production of a multi-layer finish on a substrate surface, in which
(1) a pigmented aqueous base coating which contains crosslinked polymer microparticles obtainable from polyester-polyols and polyisocyanates, is applied to the substrate surface,
(2) a polymer film is formed from the composition applied in stage (1),
(3) a transparent topcoat is applied to the basecoat thus obtained and
(4) the basecoat is then stoved together with the topcoat.
The invention also relates to a water-borne coating which contains crosslinked polymer microparticles obtainable from polyester-polyols and polyisocyanates and to the use of this coating for the production of filler and/or stone-chip intermediate primer layers in automotive finishes.
The process described above can be employed in particular in automotive finishing to produce multi-layer finishs of the basecoat-clearcoat type--in particular for the production of metallic effect finishes (compare, for example, German Offenlegungsschrift 3,606,512).
In the preparation of the crosslinked polymer microparticles by the process disclosed in German Offenlegungsschrift 3,606,512, dispersions having a relatively high coagulate content and an unsatisfactory storage stability are as a rule obtained. Another disadvantage of the polymer microparticles disclosed in German Offenlegungsschrift 3,606,512 is that aqueous metallic effect coatings which contain these polymer microparticles often display a relatively high evolution of hydrogen.
The object on which the present invention is based is to improve the process described in the precharacterizing clause of the main claim.
This object is achieved, surprisingly, by employing in the process described in the precharacterizing clause a basecoat which contains crosslinked polymer microparticles which are obtainable by
(A) reacting a polyester-polyol or a mixture of polyester-polyols with a polyisocyanate or with a mixture of polyisocyanates and
(B) when at least 25% of the NCO groups have reacted, dispersing the resulting reaction mixture in water.
In the first step of the process for the preparation of the polymer microparticles employed according to the invention, a polyester-polyol or a mixture of polyester-polyols with a polyisocyanate or with a mixture of polyisocyanates are reacted with one another so that at least 25%, preferably 30 to 60 and particularly preferably 35 to 45%, of the NCO groups contained in the reaction mixture are reacted. The prepolymers obtained in this manner are then dispersed in water, where they react completely to give crosslinked polymer microparticles.
In order to obtain crosslinked polymer microparticles, the OH functionality of at least part of the polyester-polyol component must be more than 2 and/or the NCO functionality of at least part of the polyisocycanate component must be more than 2. Polyester-polyols or polyester-polyol mixtures having an average OH functionality of 2.0 to 4.0, preferably 2.0 to 3.0, particularly preferably 2.2 to 2.6, and polyisocyanates or polyisocyanate mixtures having an average NCO functionality of 2.0 to 4.0, preferably 2.0 to 3.0, particularly preferably 2.9 to 3.1, are advantageously employed.
In order to obtain stable polymer microparticle dispersions, at least part of the polyester-polyol components and/or at least part of the polyisocyanate component must contain stabilizing ionic and/or nonionic groups. The stabilizing groups are preferably in the polyester-polyol component. Stabilizing groups which are employed are preferably ionic, particularly preferably anionic, groups, such as, for example, carboxylate, sulfonic acid and phosphate groups. Carboxylate groups are especially preferably employed as stabilizing groups. Poly(oxyalkylene) groups, such as, for example, poly(oxyethylene), poly(oxypropylene) and poly(oxyethyleneoxypropylene) groups, are mentioned as an example of nonionic stabilizing groups.
The content of stabilizing groups needed for formation of a stable dispersion can be determined with the aid of simple
REFERENCES:
patent: 4172191 (1979-10-01), Nachtkamp et al.
patent: 4558090 (1985-12-01), Drexler et al.
patent: 4822685 (1989-04-01), Perez et al.
patent: 4859743 (1989-08-01), Ambrose et al.
patent: 4914148 (1990-04-01), Mille et al.
patent: 4945128 (1990-07-01), Mille et al.
patent: 5075372 (1991-12-01), Mille et al.
Baltus Wolfgang
Berg Jan
Dobbelstein, deceased Arnold
BASF Lacke
Cooney Jr. John M.
Farben AG
Seidleck James J.
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