DD235267A1 - TEMPORARY CORROSION PROTECTION FOR SURFACE-TREATED STEEL SHEETS AND PROFILES - Google Patents

Abstract

The invention relates to the production of a temporally closed temporary corrosion protection layer on packetized surface-finished steel sheets and profiles for preventing corrosion damage, in particular by condensation. According to the invention, the elements to be preserved are provided on all sides with a protective layer of a solid wax. The solid wax is a mixture of post-treated paraffinic hydrocarbons from high boiling selectively refined petroleum fractions with an oil content of 25-35% and paraffin content of 65-75%. Other characteristic data are: Melting point 50-60C Viscosity at 90C6-8 c StThe invention is applicable to the production of highly refined metallurgical products.

Description

Field of application of the invention

The invention relates to the generation of a temporally closed temporary corrosion protection layer on surface-finished steel sheets and profiles for preventing corrosion damage during transport and storage in the packaged state.

The following statements relate in particular to the corrosion protection in the production of profiles made of plastic-coated sheet steel. It is within the scope of the invention to apply the disclosed solution also for flat surface-finished steel sheets.

Characteristic of the known technical solutions

The surface-treated material is exposed to high stresses, especially during forming. The coating materials are stretched in the forming zones by stretching the outer fibers and thereby reduced in their layer thickness. Due to the porosity of the coating systems, corrosion damage can occur here as well as on undeformed profile parts during long-term condensation. Intense condensation is when the condensation can not evaporate due to external conditions such. B. in the packetized profile sheet package. The onset during transport and storage condensation on o. G. Weaknesses of the double-sided coating as well as on the unprotected cutting and side edges of the profiled sheets forms the origin of long-term corrosion damage to the subsequently used surface-finished profiled sheet and leads to a reduction in the utility value properties and, consequently, to a decisive reduction in the service life of these products.

Internationally, it is common to certain ranges, the particularly high corrosion loads during transport and storage - such. B. in overseas transport in tropical climates - are exposed to one-sided with organic protective films prior to profiling. For this purpose, the film is laminated to the top after the organic coating.

The much larger part of surface-finished profiles should be selected by choosing a suitable packaging -. As wooden boxes, tin boxes, special containers u. a. - be protected against corrosion damage during transport and storage. The packaging of the profile packages is done outside the profiling mostly manually.

It is known that structurally conditioned existing cavities, eg. B. in body parts, preserved. In DE-OS 2,755,947 such a method is described, wherein the cavities are flooded with liquefied contactor wax; After subsequent heating of the body parts filled with contactor wax, the excess liquid wax is drained off.

Furthermore, a method is described in DE-OS 2,704,126, are preserved in the elongated tubes and profiles made of steel. In this case, an uneven wax layer is smeared on the axially linear or axially rotating profiled profile body of rod-shaped pressed wax bodies. The wax layer is melted on subsequent heating to a closed film.

It is known that painted metal parts are preserved with a special protective wax.

These protective waxes are wax components or wax suspensions incorporated in a solvent. Depending on the dispersion or solvent, they have a different drying time of 30 minutes to 12 hours.

As masses for the production of a protective coating on metals u. a. known:

- oxygen-containing wax, emulsifier, white-colored powder of inorganic material (DE-OS 3 216 550)

- Microcrystalline wax, oil, alkali metal sulfonate (DE-AS 2 330 375)

- Wax, mineral oil, ester compounds, metal naphthenate (DE-AS 2 044 285)

- Alkyl-Venylacetate-Copolymers and Paraffins (DD-PS 125 138)

The above solutions are subject to the following shortcomings:

The lamination of protective films takes place only on one side on the upper side of the tape, the underside and the profile edges remain unprotected. The removal of the protective film from the individual profiled sheets before use by the processor is very laborious and costly for this.

The production and installation of appropriate packaging elements and containers is usually very material, cost and time consuming. Despite high packaging costs, condensation can not be avoided if there are corresponding environmental influences. The removal of the packaging elements and removal of the profiled sheets from the containers at the processor is labor-intensive and laborious for him. The packaging is not returned due to high transport costs and thus represents a financial loss.

The cited preserved with liquid protective wax cavities in car body parts are structurally related and require a complex long-term protection, as this significantly affects the utility properties. These cavities differ greatly from the only temporary, inevitably resulting during the transport and storage of packetized cavities within the packages. Package cavities require temporary corrosion protection due to the problem of condensation. Transport preservation of packaged and packed profiles by wax flooding is unsuitable for such applications due to the uncontrolled, remaining in the cavities waxes and problems occurring during the unstacking of the profile packages and subsequent, consuming wax removal.

The smearing and subsequent melting of solid wax is practically only on rotationally symmetric bodies such. B. pipes, apply. For non-rotating and surface-finished broadband profiles, this method is unsuitable for technical and economic reasons.

The use of the known types of protective wax for the stated purpose is unsuitable, since these agents have an unacceptably high drying time for the process of continuous profiling, which adversely affects the capacity of the continuously operating equipment. Another deficiency is that prior to processing or use of the preserved elements, the applied protective layer must be removed. This process step is laborious and in most cases requires the use of solvents or industrial cleaners. Linked to this are compliance with safety regulations, additional environmental impact and cost-effectiveness issues. Similar problems should also be considered when using hot water or steam with the same aim.

Object of the invention

The object of the invention is to achieve a closed temporary corrosion layer on surface-finished steel sheets and profiles for the all-round preservation of packaged transport and storage units from condensation, which has no adverse effect on the subsequent processing of the semi-finished products.

Explanation of the essence of the invention

The object of the invention is to develop a temporary corrosion protection for surface-finished steel sheets and profiles, which causes an all-round protection over an influenceable period and can be removed from the coated substrate without the use of additional agents or substances.

According to the invention the object is achieved in that optionally on the surface-finished sheet immediately after a profiling a fine mist of heated at 70-100 ⁰ C solid wax is sprayed.

The solid wax according to the invention is a mixture of post-treated paraffin hydrocarbons from high-boiling selectively refined petroleum fractions with the following parameters:

oil content 25-35% paraffin content 65-75% melting temperature 50-60 ° C Viscosity ν at 90 ^° C. 6-8 c St

It contains no water-soluble acids and bases and is free from any solvents. Immediately after application, the solid wax forms a solid non-porous protective layer at room temperatures.

The protective layer thickness to be selected is adjustable depending on the desired preservation time and the respective weathering coefficient, depending on the product range climate zone, since the anticorrosion layer has the surprising property to weather without residue without further effects solely by atmospheric influences in a relatively short time. There are no obvious adverse effects on the surfaces of the previously preserved material

embodiment

The invention will be explained in more detail below using an exemplary embodiment.

As a temporary corrosion inhibitor known under the trade name "Zeresin" solid wax is used, which is used in the usual way for the production of ornamental candles, pesticides, molding compositions or textile auxiliaries and is characterized by the following values:

oil content approximately 30% paraffin content approximately 70% melting temperature 55 ° C Viscosity at 90 ^° C. 7 c St

The heated to a temperature of 80-90 ⁰ C solid wax is sprayed on both sides with a layer thickness of 25 μτη immediately after completion of the Profiliervorganges in the form of a wax over the entire width of the profiled sheet produced in a continuous profiling plant for plastic-coated trapezoidal sheets, including its side edges , The t / Vachsnebelpartikel deposit on the profile surface to a protective layer closed on all sides.

As a result of the rapid solidification of the applied protective wax at room temperature, no contamination of the outlet part of the profiling occurs.

The degradation of this temporary corrosion protection layer is primarily due to atmospheric influences such as wind and rain as well as by sweating of oil in the heat and embrittlement of the solid hydrocarbons.

Claims (3)

Invention claim: 1. Temporary corrosion protection for surface-treated steel sheets and profiles as a protective wax, characterized in that the elements to be preserved on all sides with a protective layer of a solid wax, consisting of solid mixtures of post-treated paraffin hydrocarbons from high-boiling selectively refined petroleum fractions with an oil content of 25-35% and Paraffin content of 65-75% and characterized by the parameters melting temperature 50-60 ^C C and viscosity at 90 ⁰ C of 6-8 c St be provided. 2. Temporary corrosion protection according to item 1, characterized in that the protection is applied in continuous profiling systems immediately after the profiling on the finished product. 3. Temporary corrosion protection according to item 1 and 2, characterized in that the solid wax layer is sprayed as a mist on the product to be preserved.