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
1996-03-22
2003-05-06
Morris, Terrel (Department: 1771)
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...
C524S591000, C524S839000, C524S840000, C428S903300, C427S407100, C427S409000, C239S120000, C239S124000, C521S040000, C521S040500
Reexamination Certificate
active
06559220
ABSTRACT:
The invention relates to the preparation of a water-dilutable paint capable of protecting a painted surface against stone chips and compensation primer, to their use and to processes for producing the same, especially in the motorcar industry.
DESCRIPTION OF PRIOR ART
A basic problem in the lacquering of surfaces, particularly surfaces of automobile bodies, is the resistance of the overall lacquer to chipping by stones. The stone impact resistance of conventional paints depends substantially on the surface primer layer located on the electrocoat layer. The surface primer layer, having a thickness of about 30 to 40 &mgr;m, smoothes the rough surface of the crude automobile body to allow subsequent coating with a covering lacquer, fills up minor surface inequalities, and mainly offers protection against mechanical attacks (stone chip protection function).
A conventional automobile lacquer coating according to the so-called “base coat/clear coat process” consists, for example, of a total of four layers. These four layers are applied one after the other in separate lacquering devices. The first layer, directly located on the car sheet metal, is the electrocoat layer which is applied by electro-dipcoating—mainly cathodic dipcoating (CDC)—for protection against corrosion. The nature of the electro-dipcoating prevents the formation of overspray.
The second layer, located on the electrocoat layer and having a layer thickness of about 30 to 40 &mgr;m is the so-called surface primer layer which, on the one hand, smoothes the rough surface of the crude automobile body to allow subsequent coating with a covering lacquer, it also levels minor surface inequalities and mainly offers protection against mechanical attacks (stone chip protection function). This layer is substantially produced by electrostatic application of a baking enamel, for example, with electrostatic high rotation bell, followed by baking at temperatures of above 160° C.
The third layer, located on the surfacer primer layer, is the base coat layer which imparts to the automobile body the desired color by virtue of adequate pigments. The water soluble base coat is applied by conventional spray methods.
The fourth and uppermost layer, located on the base coat layer, is the clear coat layer which, analogous to the base coat layer, is applied by conventional spray methods and, which on the one hand, imparts the desired lustre and, on the other hand, protects the base coat against environmental factors (UV radiation, salt water etc.).
The object of the invention is to produce a paint which protects against stone chip which meets the requirements of the tests prescribed by the automobile industry and, at the same time, takes over the function of the conventional surface primer layer or the function of the conventional surface primer layer and the conventional base coat layer.
SUMMARY OF THE INVENTION
This problem is solved in the present invention by providing a water-dilutable paint capable of protecting the painted surface against stone chips (hereinafter referred to as “stone chip protection paint”), containing from 20 to 60% by weight binders and from 2 to 10% by weight pigments, and a water-dilutable compensation primer, containing from 40 to 80% by weight binders. The compensation primer may additionally contain up to 20% by weight pigments.
Pigments, as defined by the present invention, include inorganic or organic multicoloured or achromatic colorants that are practically insoluble in the medium in which they are applied, such as described, for example, in “Glasurit-Handbuch Lacke und Farben”, 11th edition, published by Curt R. Vincentz, Hannover 1984, p. 97-108, i.e. carbon black titanium dioxide, effect pigments, such as aluminum bronzes, mica pigments and the like.
A binder as defined here and in the text following includes substances which bond together similar or different kinds of substances, in particular the non-volatile component of a lacquer without pigment and filler, but including plasticizers, drying agents and other non-volatile additives, preferably the water compatible film-forming resins, such as polyester, polyurethane and acrylate resins and the like, as described, for example, in “Glasurit-Handbuch Lacke und Farben”, loc. cit. p. 19-96 or in H. Wagner, H. F. Sarx “Lackkunstharz e”, Carl Hanser Verlag Munich 1972.
In a further embodiment of the invention, the ratio of binders to pigments in the water-dilutable stone chip protection paint is between 5:1 and 12:1 or between 10:1 and 15:1 in the case of the water-dilutable compensation primer.
Inasmuch as the water-dilutable stone chip protection paint or the compensation primer contains pigments, the latter can be an effect pigment, in particular an aluminium bronze.
In a preferred embodiment of the invention, the binder of the stone chip protection primer or the compensation paint is a water compatible blocked isocyanate, a polyurethane resin, a polyester resin and/or melamine resin.
In a further embodiment of the present invention, the polyester resin has of the present invention a molecular weight of from 5,000 to 10,000; exhibits an adequate number of carboxyl groups which after neutralization with bases impart to the polyester resin sufficient water-dilutable properties; and contains functional groups, in particular hydroxyl groups which render the polyester resin cross-linkable.
The polyester resin can have an OH number of from 20 to 80, in particular from 30 to 60 and an acid number between 10 and 50, in particular from 15 to 35.
Its glass transition temperature (Tg) may be between −20 and +30. In a further embodiment of the invention, the polyester resin is in particular a polycondensation product of a diol and a dicarboxylic acid in the presence of a component containing more than 2 functional groups.
The diol is selected from the group consisting of 1,6-hexanediol, neopentyl glycol, 1,4-dimethylolcyclohexane, hydroxypivalic acid neopentyl glycol ester (HPN), perhydrogenated bisphenol A, trimethylolpropane and trimethylolpropane monoallyl ether.
The dicarboxylic acid is selected from the group consisting of adipic acid, phthalic acid, isophthalic acid, hexahydrophthalic acid, tetrahydrophthalic acid or their possible anhydrides, in particular from the group of dimeric fatty acids.
The component containing more than 2 functional groups may be a triol, a tricarboxylic acid, a monohydroxydicarboxylic acid, in particular a dihydroxymonocarboxylic acid, preferably trimellitic acid, trimethylolpropane and dimethylolpropionic acid.
The best properties can be achieved with binders exhibiting elastomeric characteristics after baking. These can be specific polyurethanes in which, due to their segmented structure, a specific sequence of soft and hard segments is observed. Preferred binders are soft polyester resins having a high molecular weight and a high hydroxy-functionality, obtained by polycondensation of dimeric fatty acids and polyalcohols, preferably diols, their crosslinked sites being produced by trifunctional (hydroxy)carboxylic acids. These polyester resins are also used with blocked polyisocyanates or melamine resins as cross-linking agents.
Furthermore, the water-dilutable stone impact-protection paint or compensation primer can additionally contain organic solvents and additives.
The term solvent as used hereinafter includes those organic substances which can dissolve other substances in a physical manner, such as, e.g., lower alcohols, glycol ether, lower ketones, in particular organic solvents which are substantially miscible with water, such as butanol, isopropanol, methylethyl ketone and many others, such as described for example, in “Glasurit-Handbuch Lacke und Farben”, loc. cit. pages 117-138.
Additives are defined as substances that are added in small amounts to other substances, in particular liquid substances, to change their properties in a desired manner or to facilitate their processing. Additives include gloss products, wetting agents, drying agents sedimentation inhibitors, antifloating agents, film-inhibiting agent
Bollig & Kemper GmbH & Co. KG
Cohen & Pontani, Lieberman & Pavane
Guarriello John J.
Morris Terrel
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