Semifinished Product, Method of Production and Use Thereof

Abstract

A semifinished product is disclosed and includes a high-quality, weather-resistant coating. Also disclosed is a method for manufacturing the semifinished product and the use thereof.

Claims

1. A semifinished product, the semifinished product comprising a metallic core layer and a polymer coating with a formulation comprising from 5 to 70% by weight of hydroxy-functional fluoropolymers, from 5 to 70% by weight of polyesters based on di- or polycarboxylic acids or on derivatives of these and on aliphatic or cycloaliphatic di- or polyols, where at least one aliphatic or cycloaliphatic di- or polycarboxylic acid or derivatives thereof must be present in the polyester, from 2 to 25% by weight of crosslinking agents, from 0.01 to 2% by weight of crosslinking catalysts, up to 20% by weight of UV absorbers and up to 10% by weight of UV stabilizers, wherein a metallic anticorrosion layer has been provided to the core layer, and wherein the metallic anticorrosion layer exhibits cathodic protection from corrosion in respect of the core layer.

2. The semifinished product as claimed in claim 1, wherein the core layer comprises at least one layer made of steel.

3. The semifinished product as claimed in claim 1, wherein the metallic anticorrosion layer comprises zinc, aluminum, tin, magnesium or alloys of these.

4. The semifinished product as claimed in claim 1, wherein the thickness of the core layer is from 0.2 mm to 4 mm and the thickness of the polymer coating, after drying and crosslinking, is from 0.5 to 200 m.

5. The semifinished product as claimed in claim 1, wherein the thickness of the metallic anticorrosion layer is from 1 m to 200 m.

6. The semifinished product as claimed in claim 1, wherein the polymer coating comprises organic and/or inorganic pigments or dyes.

7. A process for the coating of a semifinished product comprising the steps of: A. providing a metallic core layer B. coating the metallic core layer with a metallic anticorrosion layer C. applying to the coated metallic core layer a polymer coating with a formulation comprising from 5 to 70% by weight of hydroxy-functional fluoropolymers, from 5 to 70% by weight of polyesters based on di- or polycarboxylic acids or on derivatives of these and on aliphatic or cycloaliphatic di- or polyols, wherein at least one aliphatic or cycloaliphatic di- or polycarboxylic acid or derivatives thereof must be present in the polyester, from 2 to 25% by weight of crosslinking agents, from 0.01 to 2% by weight of crosslinking catalysts, up to 20% by weight of UV absorbers and up to 10% by weight of UV stabilizers; and D. drying and/or calcinating of the polymer coating.

8. The process as claimed in claim 7, wherein, after the application of the anticorrosion layer (step B) and the application of the polymer coating (step C), a heat-treatment is carried out.

9. The process as claimed in claim 7, wherein the resultant coating is provided together with a further scratch-resistant coating, conductive layer, antisoiling coating and/or reflection-increasing layers or other optically functional layers.

10. The use of a semifinished product as claimed in claim 1 in vehicle construction, for packaging, for household equipment or in the construction sector for the construction of facades and of roofs, in the fitting-out of interiors and surface-finishing, and also in the design/construction of other metal structures.

11. The semifinished product as claimed in claim 2, wherein the metallic anticorrosion layer comprises zinc, aluminum, tin, magnesium or alloys of these.

12. The semifinished product as claimed in claim 2, wherein the thickness of the core layer is from 0.2 mm to 4 mm and the thickness of the polymer coating, after drying and crosslinking, is from 0.5 to 200 m.

13. The semifinished product as claimed in claim 3, wherein the thickness of the core layer is from 0.2 mm to 4 mm and the thickness of the polymer coating, after drying and crosslinking, is from 0.5 to 200 m.

14. The semifinished product as claimed in claim 2, wherein the thickness of the metallic anticorrosion layer is from 1 m to 200 m.

15. The semifinished product as claimed in claim 3, wherein the thickness of the metallic anticorrosion layer is from 1 m to 200 m.

16. The semifinished product as claimed in claim 4, wherein the thickness of the metallic anticorrosion layer is from 1 m to 200 m.

17. The semifinished product as claimed in claim 2, wherein the polymer coating comprises organic and/or inorganic pigments or dyes.

18. The semifinished product as claimed in claim 3, wherein the polymer coating comprises organic and/or inorganic pigments or dyes.

19. The semifinished product as claimed in claim 4, wherein the polymer coating comprises organic and/or inorganic pigments or dyes.

20. The semifinished product as claimed in claim 5, wherein the polymer coating comprises organic and/or inorganic pigments or dyes.

Description

DESCRIPTION OF THE INVENTION

[0060] In the process of the invention for the coating of a semifinished product, the semifinished product is first provided (A: provision of a metallic core layer), then a metallic anticorrosion layer is provided thereto (B: coating of the core layer with a metallic anticorrosion layer) and the material is then coated with a polymer coating with a formulation described above (C: application of a polymer coating with a formulation as described above), and the coating is then dried and/or calcined (D: subsequent drying and/or calcination of the polymer coating). The formulation constituents crosslink here to the polymer coating.

[0061] The metallic anticorrosion layer is preferably applied by means of a hot-dip-coating process, or via an electrolytic or galvanic coating process.

[0062] In alternative embodiments, it is also possible to produce the metallic anticorrosion layer by means of other plating processes, for example roll plating, PVD processes or CVD processes.

[0063] Application of the metallic anticorrosion layer can optionally be followed by a heat treatment in order to improve the structure of the anticorrosion layer and/or bonding thereof to the core layer, for example via diffusion processes.

[0064] Before the application of the polymer coating it is optionally possible to pretreat the surface of the anticorrosion layer.

[0065] The process for the coating of semifinished products with the polymer coating has a plurality of embodiments. In the simplest embodiment, the coating takes place directly on to the anticorrosion layer. In a process that is in particular used for this purpose, the formulation in organic solution is applied together with other formulation constituents in the form of organosol to the substrate, and the applied layer is then dried. The coating method here is by way of example knife coating, roll coating, dip coating, curtain coating, or spray coating. The crosslinking of the coating takes place in parallel with drying.

[0066] In a particularly preferred, but not exclusive, variant of the abovementioned coating variant of the present application, the formulations are used in the context of coil-coating processes. Coil coating is a process for the single- or double-sided coating of surfaces, for example steel coil or aluminum coil. The resultant material is a composite material made of a metallic carrier material comprising a core layer and anticorrosion layer, optionally pretreated, and of an organic polymer coating. Methods for, and embodiments of, coil coating processes are known to the person skilled in the art.

[0067] In a second embodiment, the polymer coating is realized in the form of a surface-finishing film, equipped with the coating formulation and applied to the respective substrate material or semifinished product. In this case the coating formulation is first coated onto an appropriate film substrate material, thus adhering securely thereto. This surface-finishing film is applied subsequently to the respective finished substrate material. The underside of the surface-finishing film here has been either coated with a self-adhesive formulation or equipped with a hot melt or with an adhesive layer. A temperature- and pressure-assisted application procedure bonds this modified underside on the finished substrate material.

[0068] By way of the properties of the material of the surface-finishing film it is thus possible to realize further product features, including for example optical features. This type of process is moreover very flexible: by way of example, it can be used in situ when semifinished products to be coated are relatively large, without use of solvents or of high temperatures.

[0069] In a third variant, similar to the second embodiment, a heat-transfer process is applied to the coating formulation in order to apply the polymer coating to the respective substrate material.

[0070] In this case, an appropriate carrier material made of film or of paper is equipped in a first coating step with a release layer which permits heat-transfer, to the respective substrate material, of the coating formulation applied in a second coating step.

[0071] It is optionally possible here, if necessary, in a third coating step, to apply an adhesive layer which ensures appropriate adhesion of the heat-transfer layer structure on the respective substrate material.

[0072] A fourth embodiment is provided by solvent-free powder coating. Suitable processes and embodiments relating thereto are well known to the person skilled in the art.

[0073] One or more further functional layers can then optionally be provided to the polymer coating. These can by way of example be a scratch-resistant coating, a conductive layer, an antisoiling coating and/or a reflection-increasing layer, or other optically functional layers. These additional layers can by way of example be applied by means of Physical Vapor Deposition (PVD) or Chemical Vapor Deposition (CVD).

[0074] It is optionally possible to apply an additional scratch-resistant coating for further improvement of scratch resistance. Scratch-resistant coatings can by way of example be silicon oxide layers applied directly by means of PVD or CVD.

[0075] The surface of the composite moldings can moreover have what is known as an antisoiling coating, in order to facilitate cleaning. Again, this coating can be applied by means of PVD or CVD.

[0076] In another example of an option, there is additionally a further, comparatively thin, extremely abrasion-resistant layer located on the polymer coating. This is a particularly hard thermoset layer, the thickness of which is preferably below 5 m, particularly preferably from 0.5 to 2.0 m. This layer can by way of example be produced from a polysilazane formulation. Application sectors for the semifinished products of the invention are found in particular in architecture, allowing creativity in the construction of facades and of roofs and for surface-finishing, and also in the design/construction of other metal structures. This applies in particular in highly stressed outdoor applications, for example sports stadiums, factory/industrial plant structures, bridge construction, transport, marine applications, etc. However, the advantages can also be utilized for indoor applications. Other application sectors for the use of semifinished products of the invention are found in vehicle construction, where this in particular comprises not only private and commercial vehicles but also shipbuilding and aircraft construction, and special-purpose vehicles. Another sector for use of semifinished products of the invention is found in the field of packaging, because the advantages are especially relevant to food packaging. The principle here is to combine long life in relation to aesthetic considerations with the traditional criteria of powerful protection from corrosion. In another preferred embodiment, the metal structures are constituents of household equipment (white goods), in particular of stoves, refrigerators, washing machines or dishwashers.

[0077] It is assumed that no further information is required to permit a person skilled in the art to make extensive use of the above description. The preferred embodiments and examples are therefore to be interpreted as disclosure that is merely descriptive and certainly not in any way restrictive.

[0078] Alternative embodiments of the present invention can be obtained in analogous manner.

EXAMPLES

[0079] Studies relating to the compatibility of polyesters and of fluoropolymers:

TABLE-US-00001 Polyester:Lumiflon LF 200F ratio Example Polyester 20:80 50:50 80:20 Example 1 P1 extremely extremely extremely cloudy cloudy cloudy Example 2 P2 extremely extremely extremely cloudy cloudy cloudy Example 3 P3 clear minimal clear clouding Example 4 P4 clear clear clear P1: Dynapol LH 744-23, Evonik Industries AG, polyester based on 45 mol % of aliphatic dicarboxylic acid P2: Dynapol LH 538-02, Evonik Industries AG, polyester based on 50 mol % of aliphatic dicarboxylic acid, and also on cycloaliphatic dicarboxylic anhydride P3: Dynapol LH 748-02/B, Evonik Industries AG, polyester based on 100 mol % of cycloaliphatic dicarboxylic anhydride P4: Dynapol LH 750-28, Evonik Industries AG, polyester based on 100 mol % of cycloaliphatic dicarboxylic anhydride The molar concentrations stated are based in each case on the acid content of the polyester concerned. Lumiflon LF 200, Asahi Glass Chemicals, hydroxy-functional fluoropolymer, based on FEVE (fluorinated ethylene vinyl ether)

TABLE-US-00002 Polyester:Lumiflon LF 916F ratio Example Polyester 20:80 50:50 80:20 Example 5 P1 extremely extremely extremely cloudy cloudy cloudy Example 6 P2 clear clear extremely cloudy Example 7 P3 clear clear clear Example 8 P4 clear clear clear Lumiflon LF 916F, Asahi Glass Chemicals, hydroxy-functional fluoropolymer, based on fluorinated ethylene vinyl ether (FEVE).

[0080] Adequate compatibility with the fluoropolymer-polyol component Lumiflon LF is possessed especially by the polyesters P3 and P4, based solely on aliphatic dicarboxylic acids or appropriate derivatives.