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Polyamide-imide coated substrate

a technology of polyamideimide and substrate, applied in the direction of record information storage, transportation and packaging, instruments, etc., can solve the problems of increasing manufacturing costs, introducing environmental and safety issues, increasing the cost of manufacturing automotive parts, etc., and achieves cost savings, excellent performance, and cost reduction

Inactive Publication Date: 2014-06-05
TATA STEEL NEDERLAND TECH BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention offers an advantage to automotive manufacturers through the use of a single layer of polyamide-imide that can replace both the phosphate layer and the electrophoretic layer. This layer exhibits improved corrosion resistance, humidity barrier properties, friction and adhesion properties, and does not require anti-corrosion pigments. The polyamide-imide layer has a thermal stability between -60°C and 400°C, meaning it will not crack or degrade at reduced or elevated temperatures. It also has a dry film thickness between 3 and 5 μm, which exhibits excellent performance at reduced cost relative to other thicker coatings. The layer has a coefficient of friction between 0.13 and 0.25 at a temperature between -10 and 120°C, which meets automotive manufacturing standards even without lubricant application. The polyamide-imide layer is lubricating, which means an additional step of providing a lubricant and / or texture during subsequent forming and / or stamping operations is not required.

Problems solved by technology

This is not trivial and increases manufacturing costs.
The use of phosphoric acid also introduces environmental and safety issues related to the handling and disposal of such solutions.
The use of electrophoretic deposition to apply organic coatings increases the cost of manufacturing automotive parts due to the high voltages that are required to apply such coatings.

Method used

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  • Polyamide-imide coated substrate

Examples

Experimental program
Comparison scheme
Effect test

example 1

Preparation of Aqueous Polyamide-Amic Acid Solution

[0031]200 g of polyamide amic acid (TORLON® Al-50 from Solvay Advanced Polymers, available as wet powder with a solids content of 35 wt %, is dispersed in a mixture of water (485 g) and dimethyl ethanol amine (50 g). The dispersion is then warmed to a temperature between 60 and 70° C. until the solids dissolve to produce a brown aqueous solution having about 9% by weight polyamide-amic acid.

example 2

Application of the Aqueous Polyamide-Amic Acid Solution

[0032]The aqueous polyamide-amic acid solution is cooled to room temperature and 0.5 wt % of wetting agent BYK® 380N (from Byk Chemie) is added thereto. This solution is applied on a galvanised steel strip by roller coating at a speed of 150-250 m / min. The applied coating is then cured via near-infrared at s temperature of 260° C. for 5-10 s to remove the aqueous solvent and form a layer of polyamide-imide on the galvanised steel strip surface.

Experiments

[0033]In the experiments hereunder the layer of polyamide-imide has been applied on a galvanised steel strip (E1).The present invention (E1) has been compared to a number of commercial coating systems that are used in the automotive industry to reduce the effects of corrosion caused by surface defects, scratches and cut edges. C1-C3 are comparative examples in which galvanised steel strips have been provided with titanium phosphate (C1), a layer of acrylic containing chromate pi...

experiment 1

est

[0035]In order to evaluate the performance of the layer polyamide-imide in respect of its corrosion resistance the coated steel strip of the invention was subjected to a salt spray test. The salt spray test was performed according to ASTM B117, using a 5% NaCl solution at 35° C., with an overpressure of 2-3.5 mbar (200 to 350 Pascal) to create fog inside the spray chamber.

[0036]Table 1 shows the corrosion resistance properties of a galvanised steel strip provided with a layer of polyamide-imide (E1-E4) and comparative examples C1-C4. All thicknesses relate to the thickness of the respective layers, i.e. exclusive of the underlying galvanised coating layer. It can be seen from Table 1 that the present invention El offers a significant improvement in corrosion resistance relative to C1-03 with just 2% white rust being observed after 15 days and 5% white rust being observed after 25 days. Similar results are obtained for examples E2-E4. The observed improvement in corrosion resistan...

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Abstract

Steel substrate suitable for forming operations which includes a coating thereon wherein the coating includes a corrosion resistant layer of polyamide-imide having a dry film thickness between 1 and 10 μm.

Description

FILED OF THE INVENTION[0001]The present invention relates to a steel substrate comprising a corrosion protective coating and to a method for making the same. The present invention further relates to the use of the steel substrate in forming operations to form a part.BACKGROUND OF THE INVENTION[0002]Galvanized steel is used in applications where rust resistance is needed, for instance, in the automotive industry where the zinc layer reduces the onset of rust at exposed edges and surfaces.[0003]Additional coating layers are provided to make the galvanised steel substrate more aesthetically pleasing and to further protect the steel substrate from corrosion. In this respect galvanised steel substrates are first provided with a phosphate coating (2-5 μm) to enhance paint adhesion, by enhancing paint adhesion such phosphate coatings indirectly enhance corrosion resistance.[0004]The application of the phosphate coating comprises the steps of dissolving metal phosphate salts in a solution o...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C23F11/00
CPCC23F11/00C09D5/08C09D179/08C08G73/14Y10T428/265Y10T29/49
Inventor FLORES RAMIREZ, JOSE REYESWAINER, MAGALI AUDREY VALERIAHANNOUR, FOUZIA
Owner TATA STEEL NEDERLAND TECH BV
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