JP2764165B2 - Base treatment method for resin coating of metal material - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a metal material such as an aluminum material with, for example, a fluororesin, on a surface to be coated with the resin in advance.

Conventional technology and its problems In general, when a fluororesin is applied to the surface of an aluminum material by coating or bonding, adhesion between the surface to be applied and the resin is important, and various methods have been used to improve the adhesion. A roughening method has been performed. One of the methods is an etching method. In this method, an etching resist is printed on a surface to be coated with a resin in a predetermined pattern to form a mask portion and a non-mask portion of the resist, and then the non-mask portion is chemically or electrically etched to anchor the resin. A recess is formed, and then the resist remaining on the mask portion is removed.

However, in this method, since the mask portion on which the resist is printed is not necessarily etched, when the fluororesin is coated after removing the resist, there is a problem that the adhesion between the aluminum material and the resin is very poor in this portion. was there.

In view of the above, the present invention can significantly improve the adhesiveness between a non-etched portion of an aluminum material and a resin in a base treatment employing chemical or electrical etching, and can improve the surface of a metal material. A dense and uniform rough surface pattern can be formed extremely stably by etching, and the etched concave portions (pores) have a substantially constant size, and a large number of fine irregularities are formed on the inner surface of the concave portion. It is an object of the present invention to provide a base treatment method in which the adhesion of a resin to a metal material is extremely good due to an excellent anchoring effect.

Means for Solving the Problems The undercoating method for coating a metal material with a resin according to the present invention, in order to achieve the above object, prints an etching resist in a predetermined pattern on a surface to be coated with a resin, and forms a mask portion with the resist. In a base treatment for forming a non-mask portion and then etching the non-mask portion, the surface to be coated with the resin is roughened before printing the resist, and the entire surface to be coated with the resin is roughened with a roughness of 1 to 1. After forming a rough surface of 10 μm (Rmax), the non-mask portion is etched after the above-described resist printing, and has a tapered inner peripheral wall gradually tapering from the bottom to the opening, and has a thickness of 20 to 50 μm. It is characterized in that a large number of groove-shaped resin embedding recesses having a cross section having a depth are formed, and the inner surface of the recesses is further roughened.

In this specification, the term "aluminum"
It includes not only pure aluminum but also commercially available aluminum containing a small amount of impurities, aluminum alloys based on aluminum, and the like.

Products made of aluminum materials include rice cookers,
Examples include a rice cake sticker, a baking pan, a frying pan, a pan, a hot plate, an ice tray, an oven dish, and the like.

The method of treating the underlayer in the resin coating of the aluminum material according to the present invention is shown in the flow sheet of FIG.

First, the surface to be coated with the resin is preferably degreased. This degreasing treatment may be performed together with the cleaning treatment after the next roughening.

Then, the surface to be coated with the resin is generally roughened by a mechanical polishing method such as sandblasting, wire brushing, and feather polishing. The roughening may be performed by chemical or electrical etching. The roughness of the surface roughening is 1 to 10 μm (Rmax). The reason for this is that if the thickness is less than 1 μm, sufficient adhesion cannot be obtained.
If it exceeds m, the next printing cannot be performed clearly.

After the roughening, the resulting abrasive powder is preferably removed by an alkali or acid wash before the next printing.

Next, in the printing step, printing of the etching resist is performed by lithographic printing, intaglio printing, letterpress printing, screen printing, gravure printing, or the like. The pattern to be formed has a lattice shape, a vertical stripe shape, a horizontal stripe shape, a staggered lattice shape, or the like. In the case of a lattice pattern, a large number of square or rectangular non-mask parts are formed by the lattice mask part. Print line thickness is 0.05 ~ 0.5mm, print line pitch is
0.1 to 10 mm is preferred. The printing ink is appropriately selected according to the printing method.

Next, when performing chemical etching in the etching step, a solution of an inorganic acid such as hydrochloric acid is used. When electrical etching is performed, DC electrolysis, AC electrolysis or AC / DC superposition electrolysis is performed in an electrolytic solution containing an alkali. DC electrolytic etching is particularly preferred in that it does not damage the print resist. As a result of this etching, the non-mask portion is formed as a concave portion for anchoring the resin.

Here, the resin anchoring concave portion has a predetermined size and a cross section having an inner peripheral surface that expands in a reverse taper shape toward a tapered inner peripheral wall bottom that gradually tapers from the bottom to the opening. It is groove-shaped, and the inner surface of the resin anchor recess is roughened (see FIG. 3). The depth of the concave portion is usually 100 μm or less, preferably 20 to 50 μm.

After the etching, the resist is usually removed. The removal of the resist is performed by treating the resist surface with an inorganic acid solution or an organic solvent. However, when a fluorine resin-based printing ink is used, it is not necessary to remove the resist.

The coating of the resin on the metal material subjected to the base treatment is performed by applying an aqueous dispersion of a fluororesin such as ethylene tetrafluoride resin to the aluminum material and then performing baking. In some cases, an alumite layer is formed on the base surface before the resin film. Examples of the resin coating on the metal material include, in addition to the fluorine resin coating on the aluminum material as described above, a steel material coating with a vinyl chloride resin.

Embodiment Next, an embodiment of the present invention will be specifically described with reference to the drawings.

Example 1 In FIGS.
A 5 mm aluminum plate (A1100) (1) was used.

First, the surface of this aluminum plate (1) was mechanically polished by wire brushing to have a roughness of 5 μm (Rma
x) was roughened. The surface-roughened aluminum plate (1) was then immersed in a treatment solution comprising a 5% aqueous solution of sodium hydroxide at 50 ° C. for 1 minute to remove abrasive powder generated by the surface roughening and degrease.

Next, as shown in FIG. 2, an etching resist (2) was printed in a grid pattern on the surface of the polished aluminum plate (1) by screen printing. Here, the thickness of the grid line formed by the resist (2) is
0.2 mm, the pitch of the grid lines was 0.5 mm, and the size of the non-mask portion (3) that was not masked by the grid pattern resist (2) was 0.5 mm × 0.5 mm. As the printing ink, a white ink containing titanium oxide was used.

Then, as shown in FIG. 3, the aluminum plate (1) having the grid-patterned printing resist (2) was placed on the aluminum plate (30).
The aluminum plate (1) was used as an anode, a carbon plate was connected to the counter electrode, and a direct current electrolytic etching was performed at a current density of 20 A / dm ² for 3 minutes by dipping in an electrolytic solution composed of a 5% aqueous solution of sodium chloride at 5 ° C. Done. As a result, the non-mask portion (3) was etched, and a large number of resin anchoring concave portions (4) were formed on the surface of the aluminum plate (1). As shown in the figure, the resin anchoring concave portion (4) has a predetermined size and expands in an inverse taper shape toward the bottom of the tapered inner peripheral wall which gradually tapers from the bottom to the opening. It has a cross-sectional groove shape having an inner peripheral surface, and the inner surface of the resin anchoring concave portion (4) is roughened.

Thus, the surface of the aluminum plate (1) has a roughness of 40 μm.
(Rmax).

Next, as shown in FIG. 4, the roughened aluminum plate (1) was immersed in a hydrochloric acid solution to remove the resist (2) remaining on the mask portion. Thus, a roughened base surface was formed.

Then, as shown in FIG. 5, an aqueous dispersion of ethylene tetrafluoride resin (manufactured by DuPont, part number 456-300) was applied by spray coating on the surface of the aluminum plate (1) thus undercoated, Bake at a temperature of about 400 ° C for 10 minutes, and apply a thickness on the surface of the roughened aluminum plate (1).
A 30 μm resin coating layer (5) was formed.

Example 2 In mechanical polishing of the surface of an aluminum plate (1),
Sand blasting was performed using alumina particles instead of wire brushing, and the surface of the aluminum plate (1) was polished and roughened to a roughness of 5 μm (Rmax). Otherwise, the procedure was the same as in Example 1.

Comparative Example The surface of the aluminum plate (1) was not mechanically polished,
Otherwise, the procedure was the same as in Example 1.

Evaluation of Adhesion The resin coating layers formed in Example 1, Example 2, and Comparative Example were subjected to a peeling test in accordance with the JIS method. The results are shown in the table below.

As is clear from this table, the peel strength of the resin coating layer is significantly higher in the example where the polishing operation was performed before printing than in the comparative example where the polishing was not performed.

Advantageous Effects of the Invention The present invention provides an etching resist in a predetermined pattern on a surface to be coated with a resin, forms a mask portion and a non-mask portion with the resist, and then, in a base treatment for etching the non-mask portion, applies a resin The surface to be coated is roughened before printing the resist, and a roughened surface having a roughness of 1 to 10 μm (Rmax) is formed on the entire surface to be coated with the resin. Etching the part, having a tapered inner peripheral wall gradually tapering from the bottom to the opening, and forming a large number of resin embedded recesses having a cross-sectional groove shape having a depth of 20 to 50 μm, and further, According to the present invention, the surface on which the resist is to be printed is roughened in advance, so that the mask portion on which the resist is printed has the following characteristics. In the process Even if it is not ring, it is possible to exert a greater adhesion to the resin layer coated on this part. Therefore, it is possible to effectively solve the problem that the adhesiveness is poor in the mask portion as in the case of the related art described at the beginning of this document.

In addition, a dense and constant rough surface pattern can be formed extremely stably on the surface of the metal material by etching, and the etched concave portions (pores) have a substantially constant size. A large number of fine irregularities are formed, the adhesion of the resin to the metal material is extremely good due to the excellent anchoring effect, and particularly, roughening and etching before the resist printing on the metal material surface The synergistic effect with the roughening up to the inner surface of the concave portion by the treatment provides an effect that the adhesion of the resin coating layer to the metal material can be further increased.

[Brief description of the drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a flow sheet for carrying out the method of the present invention, and FIGS. 2 to 5 are diagrams for explaining the method of the present invention in the order of steps. The figure is a partially enlarged plan view of the aluminum plate after the printing of the etching resist, FIG. 3 is a partially enlarged sectional view of the aluminum plate having the resist printing after the etching, and FIG. 4 is a roughened aluminum plate from which the resist printing is removed after the etching. 5 is a partially enlarged cross-sectional view showing a state where the surface of the roughened aluminum plate is covered with a resin. (1) ... aluminum plate, (2) ... etching resist, (3) ... non-mask part, (4) ... concave part for resin anchoring, (5) ... resin coating layer.

Claims (1)

(57) [Claims] An etching resist is printed in a predetermined pattern on a surface to be coated with a resin, a mask portion and a non-mask portion are formed by the resist, and the resin is coated in a base treatment for etching the non-mask portion. The surface to be roughened before printing the resist, and forming a roughened surface having a roughness of 1 to 10 μm (Rmax) on the entire surface to be coated with the resin;
After the resist printing, the non-mask portion is etched and has a tapered inner peripheral wall gradually tapering from the bottom to the opening, and a large number of resin embedded recesses having a cross-sectional groove shape having a depth of 20 to 50 μm. And a roughening process for the inner surface of the concave portion.