DD302022A9 - Process for the preparation of a decorative anti-corrosion coating - Google Patents

Abstract

The invention relates to a method for producing a decorative organic corrosion protection coating with high moisture and weather resistance on surfaces of metal, in particular steel or concrete, and is particularly suitable as an exterior painting for rail vehicles. The aim of the invention is a cost-effective method for producing decorative, high-weather and moisture-resistant protective coatings for metallic and concrete substrates. The invention has as its object to develop the per se known method of applying conventional tar reaction resin paints according to the invention to the effect that in combination with a polyurethane topcoat a decorative and weather-resistant coating is achieved in which the bleeding of tar components is not to be promoted. It was found that a tar epoxy resin coating with dry film thickness between 60 and 350 microns as a primer layer and a subsequent application of a topcoat of aliphatic polyurethane reaction resin varnish with color pigments, such as titanium dioxide and an addition of 15 to 30%, based on the color pigmented master paint composition, a platy Aluminum pigment in a dry film thickness of 30 to 40 my m, a maximum of 80 to 100 my, on the cured primer layer meets the requirements as far as possible.

Description

Field of application of the invention

The invention relates to a method for producing a decorative organic corrosion protection coating with high moisture and weather resistance on surfaces of metal, especially steel, or concrete, and is particularly suitable as an exterior painting for rail vehicles.

Characteristic of the known technical solutions

Known processes, where high decorative properties and high durability are required, envisage the use of two-component two-component polyurethane coating systems or the combination of two-component epoxy coatings as a primer with 1-2 layers of two-component polyurothane topcoats. In DE 3346763.3303828 3-layer paint systems for heavy corrosion protection with good moisture resistance are presented, which consists of a solvent-type primer layer, for. Alkyd resin, epoxy resin, and free-radically polymerizable and oxidatively polymerizable solvent-free coating composition, e.g. B. oil-modified alkyd resins with curing catalyst, with a certain content of a flaky pigment, ι. Example, mica-like iron oxides, Al powder, and a top coat of air-dry type, z. As polyurethane. A disadvantage of these coating methods is not always sufficient moisture resistance and their high workload when applying the Ansti ichstoffe to achieve the required for a good corrosion protection effect mineshift thickness of ISOpm.

It has long been known that terepoyid resin paints provide excellent corrosion protection against the effects of moisture and, with just a few operations, dry film thicknesses of up to 1: 1 mm can be achieved. A disadvantage is their lower UV resistance in outdoor weathering, which causes a deterioration of the decorative appearance by chalking, loss of gloss, etc. Often, their jet-black appearance is disturbing. Since these paints tend to bloom or exude, it is virtually impossible to apply topcoats without sacrificing the visual appearance. With DE-patent 2 042835 a method was known which is intended to eliminate this disadvantage. However, the high synthetic effort required to produce such paint binders according to the invention is disadvantageous.

Object of the invention

The aim of the invention is a cost-effective method for producing decorative, high-weather and moisture-resistant Schutziiberzüge for metallic and concrete substrates.

Explanation of the essence of the invention

The object of the invention is to develop the method known per se for the use of conventional tarry reaction resin paints according to the invention in that in combination with a polyurethane topcoat paint a decorative and weather-resistant coating is achieved in which bleeding of tar constituents is not to be feared.

According to the invention is on a clean grease and stainless Obei surface, preferably steel, a tar epoxy resin paint commonly used Reieptur, consisting of

Epoxy resin, e.g. Bisphenol Epichlorhydrinkondonsat,

- Pigments, fillers, eg. Talc, silicates, chalk,

- paraffin-free coal tar or coal tar pitch,

Hardener, e.g. Amines, polyamides,

- aromatic solvents, glycols, alcohols,

odor advantageously applied by brushing, spraying or, preferably, by hydraulic pneumatic spraying with cold paint ^C of 15-25 C and warmed to 50-8O ⁰ C paint as a primer layer.

Subsequently, the coating layer is at room temperature between 24 and 48 hours, or distortion as accelerated cured to 3 hours at temperatures between 4O ⁰ C and 80 "C within 1. The dry layer diche of the paint film should be at least 60pm and no more than 350pm.

Subsequently, a polyurethane paint is added to this primer layer, based on

Stock, e.g. Acrylate, polyester polyol,

- Pigments titanium white and flaky pigment,

- hardener, e.g. aliphatic polyisocyanates,

- aromatic solvents, esters

applied as a topcoat composition, for which all important application techniques, such as pneumatic or hydraulic spraying and brushing, etc., are suitable. Dio curing can take place at room temperature or at elevated temperatures between 4O ⁰ C and 100 ° C within 0.5 to Z hours.

To obtain a consistently decorative surface, as a flaky pigment, aluminum pigment paste having the following properties for a maximum of 10 days before processing the topcoat

Solids content (%): 50-85

Spending value 000cmVg): 12-30

Leafing value (%): 30-75

and in emern concentration range of 15 to 30%, preferably 20 to 25%, based on the titanium white pigmer.lierte base paint component homogeneously incorporated.

To ensure the weather resistance of the protective coating uine dry film thickness of 30 to 40pm to a maximum of 80 to 100 μηι sufficient.

embodiment

On the cleaned and stainless steel outer surface of a refrigerated truck, a protective coating is to be applied. The primer layer of terephthalate is after homogeneous mixing of the epoxy resin with a polyamide hardener coal tar system in the ratio of 2: 1 parts by adhering to a pre-reaction time of 30 minutes by the hydraulic hot spraying method at an injection pressure of 80 to 120 bar and a coating temperature of 5O ⁰ C. to> 0 ° C, sprayed to achieve and dry film thickness of 100 to 120μηι in one operation. Curing takes place at a temperature of 50 ⁰ C over 1.5 hours and einor postcure of 24 hours at normal temperature. The polyurethane topcoat component required for the top coat is flashed in 10 parts by weight of C-8 aromatic solvent just before processing by slowly stirring in 20 parts by weight of aluminum pigment paste containing gasoline hydrocarbons as a pasting agent, having a spreading value of 12,000 cmVg and a leafing value of 65% to 70 parts by weight of the titania pigmented polyester polyol masterbatch component to homogeneity of the aluminum pigment in the paint. By adding the polyisocyanate hardener of HD I (hexamethylene diisocyanate) in the mass mixing ratio of 3: 1 and the adjustment of the processing viscosity to 30 to 40 seconds flow time (cup no. 4), the processing after about 30 minutes of reaction time with the hydraulic injection process at an effective Spray pressure of 120 to 160 bar done.

In this case, 1 to 2 operations are required to achieve the minimum layer thickness of 40pm. Subsequently, the curing is preferably carried out at a temperature of 5O ⁰ C for 1 to 2 hours.

In this way, a protective cover with high decorative effect, as required in metallic finishes for car bodies, coupled with high outdoor weathering resistance produced.

Claims (4)

A process for the preparation of a decorative primer layer and topcoat organic corrosion inhibiting coating having high moisture and weather resistance, characterized by applying a primer layer of terephthalic acid paint having a dry film thickness of 60 to 350 μm, preferably 100 to 120 μm, to the cleaned, grease-free substrate and the application of a topcoat of reaction resin varnish of the aliphatic polyurethane type with an addition of Farbpigrnenten, such as titanium dioxide, and 15 to 30%, preferably 20 to 25% of a flaky-like aluminum pigment based on the pigmented master paint composition on the hardened Grundiörungsschicht with a dry film thickness of 30 to 40Mm, rMaximal 80 to 100mm. 2. The method according to item 1, characterized in that an aluminum pigment paste having a solids content of 50 to 85%, a spreading value of 12 to 30 × 1000 cm ² / g and a leafing value of 30 to 45% is used as the aluminum pigment. 3. The method according to item 1, characterized in that for the formation of the ürundierungsschicht a Polyliocynatgehärtetes highly hydroxyl and high molecular weight tar epoxy resin or a Toer polyurethane resin binder as a coating composition is used. 4. The method according to item 1, characterized in that the curing of the primer layer is carried out at temperatures between 40 and 80 ⁰ C accelerated and the curing of the dock layer at temperatures between 40 and 100 ⁰ C is carried out.