JPH01268882A - Surface treatment of resin coating on metallic material - Google Patents

Abstract

PURPOSE:To execute the surface treatment which greatly enhances the adhesiveness of the non-etching part of a metallic material and a resin by roughening the surface to be coated with the resin prior to resist printing, then forming masked parts and unmasked parts by an etching resist and etching the unmasked parts. CONSTITUTION:The surface of the metallic material, more particularly Al material to be coated with the resin is roughened to preferably 1-10mum (Rmax) toughness by a mechanical polishing method such as, for example, sandblasting. The etching resist is then printed by planographic printing, etc., on the roughened surface to form the masked parts in grating, zigzag grating or other shapes. The size of the printing lines in this case is preferably 0.05-0.5mm and the pitch of the printing line 0.1-10mm. After the unmasked parts are subjected to, for example, DC electrolytic etching, the resist is removed by an inorg. acid soln. or org. solvent. An aq. dispersion of fluoroplastic such as tetrafluoroethylene is coated on the Al surface from which the resist is removed and thereafter, the surface is baked. The resin coating is thus executed.

Description

DETAILED DESCRIPTION OF THE INVENTION 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, in which the surface to be coated with the resin is preliminarily treated as a base.

Prior art and its problems Generally, when applying a fluororesin to the surface of an aluminum material by coating or glueing, it is important to have good adhesion between the surface to be applied and the resin, and various methods have been used to improve the adhesion. Surface roughening methods have been used. One of these methods is an etching method. This involves printing etching resist in a predetermined pattern on the surface to be coated with resin, forming masked areas and non-masked areas using the resist.
Next, the non-masked portions are etched chemically or electrically to form four resin anchoring portions, and then the resist remaining on the masked portions is removed.

However, in this method, the mask area where the resist is printed is not necessarily etched, so when the fluororesin is coated after the resist is removed, there is a problem that the adhesion between the aluminum material and the resin is very poor in this area. was there.

In view of the above points, an object of the present invention is to provide a surface treatment method that can greatly improve the adhesion between the non-etched portion of an aluminum material and a resin in surface treatment that employs chemical or electrical etching. With the goal.

Means for Solving the Problems In order to achieve the above object, the surface treatment method according to the present invention prints etching resist in a predetermined pattern on the surface to be coated with resin to form masked areas and non-masked areas by the resist. In the surface treatment in which the non-mask portions are then etched to form recesses for resin anchoring, the surface to be coated with resin is roughened before resist printing.

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

Examples of products made of aluminum include rice cookers, rice cake makers, bread makers, frying pans, pots, hot plates, ice cube trays, and oven plates.

The base treatment method for coating aluminum material with resin according to the present invention is shown in the flow sheet of FIG. 1 attached hereto.

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

The surface to be coated with resin is then roughened, generally by mechanical polishing methods such as sandblasting, wire brushing, and Chofu polishing. The surface roughening may be performed by chemical or electrical processing or soching. The roughness of the surface roughening is preferably 1 to 101111 (Rm
ax). The reason for this is that if the length is less than 1 m, sufficient adhesion cannot be obtained, and if the length exceeds 10 m, the next printing cannot be done clearly.

After surface roughening, the abrasive powder produced is preferably removed by alkaline or acid cleaning before the next printing.

Next, in the printing process, etching resist printing can be performed using lithographic printing, intaglio printing, letterpress printing, screen printing,
This is done by gravure printing, etc. The pattern formed is a lattice, vertical stripes, horizontal stripes, houndstooth check, or the like. In the case of a grid-like pattern, a large number of square or rectangular non-masked parts are formed by the grid-like mask parts. The thickness of the printed lines is preferably 0.05 to 0.5 mm, and the pitch of the printed lines is preferably 0.11-1oII. The printing ink is appropriately selected according to the printing method.

Next, in the etching step, when chemical etching is performed, a solution of an inorganic acid such as hydrochloric acid is used.

When electrical etching is performed, direct current electrolysis, alternating current electrolysis, or alternating current electrolysis is performed in an electrolytic solution containing an alkali.

Direct current electrolytic etching is particularly preferred because it does not damage the printed resist. As a result of this etching, the unmasked parts are made into four parts for resin anchoring. The depth of this recess is
Usually 1001 m, preferably 20 to 50 m.

After etching, the resist is typically removed. The resist is removed by treating the resist surface with an inorganic acid solution or an organic solvent. However, if a fluororesin-based printing ink is used, there is no need to remove the resist.

The coated metal material is coated with a resin by applying an aqueous dispersion of a fluororesin such as tetrafluoroethylene resin to the aluminum material and then baking the material. Note that an alumite layer may be formed on the underlying surface before the resin film is applied. Examples of coating metal materials with resin include coating steel materials with vinyl chloride resin, in addition to coating aluminum materials with fluororesin as described above.

Embodiments Next, embodiments of the present invention will be specifically described based on the drawings.

Example 1 In FIGS. 2 to 5, the aluminum material has a thickness of 1.
A 5 mm aluminum plate (AIloo) (1) was used.

First, the surface of this aluminum plate (1) was mechanically polished by wire brushing to a roughness of 5/11!1 (
Rmax). This roughened aluminum plate (
1) was then immersed in a treatment solution of 5% sodium hydroxide aqueous solution at 50° C. for 1 minute to remove abrasive powder produced by roughening the surface and to degrease it.

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 lines formed by resist (2) is 0.
2 mm, the pitch of the grid lines was 0.5+ni, and the size of the non-masked portion (3) not masked by the grid pattern resist (2) was 0.5 mm x 0.5 mm. As the printing ink, a white ink containing titanium oxide was used.

Next, as shown in FIG. 3, the aluminum plate (1) having the grid pattern printing resist (2) was
The aluminum plate (1) was immersed in an electrolytic solution consisting of a 5% sodium chloride aqueous solution at a temperature of 3°C, and the aluminum plate (1) was used as an anode and a carbon plate was connected to the counter electrode, and the current density was 20 A/drti'.
Direct current electrolytic etching was performed for 1 minute. As a result, the non-mask portion (3) is etched, and the aluminum plate (
A large number of resin anchoring recesses (4) were formed on the surface of 1).

In this way, the surface of the aluminum plate (1) has a roughness of 40μ@
(Rmax).

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

Next, as shown in FIG. 5, an aqueous dispersion of tetrafluoroethylene resin (manufactured by DuPont, product number 456-300) was spray coated on the surface of the aluminum plate (1) which had been subjected to the surface treatment in this way. Baking was performed at a temperature of about 400° C. for 10 minutes to form a resin coating layer (5) with a thickness of 30 μl on the surface of the roughened aluminum plate (1).

Example 2 In mechanically polishing the surface of the aluminum plate (1), sandblasting was performed using alumina particles instead of wire brushing, and the surface of the aluminum plate (1) was polished to a roughness of 5IyI (Rmax). It turned into a face. The other points were operated in the same manner as in Example 1.

Comparative Example The aluminum plate (1) was operated in the same manner as in Example 1 except that the surface of the aluminum plate (1) was not mechanically polished.

Evaluation of Adhesion A peel test was conducted on the resin coating layers formed in Example 1, Example 2, and Comparative Example 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 in the examples in which the polishing operation was performed before printing was significantly greater than in the comparative examples in which this polishing was performed.

Effects of the Invention According to the base treatment method of 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 can be etched in this area even if it is not etched in the next step. It can exhibit great adhesion to the coated resin layer. Therefore, it is possible to effectively solve the problem of poor adhesion at the mask portion as in the case of the prior art described at the beginning of this document.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a flow sheet for carrying out the method of the present invention, and FIGS. 2 to 5 are for explaining the method of the present invention in the order of steps. The figure is a partially enlarged plan view of an aluminum plate after etching resist printing, Figure 3 is a partially enlarged sectional view of an aluminum plate with resist printing after etching, and Figure 4 is a roughened aluminum plate with resist printing removed after etching. FIG. 5 is a partially enlarged sectional view of the plate, showing a state in which the surface of the roughened aluminum plate is coated with resin. (1) Aluminum plate, (2) Etching resist, (3) Non-mask portion, (4) Resin anchoring recess, (5) Resin coating layer. Above Figure 1

Claims (1)

[Claims] Etching resist is printed in a predetermined pattern on the surface to be coated with resin to form a masked part and a non-masked part by the resist, and then the non-masked part is etched.In the base treatment, the surface to be coated with resin is printed with resist. A surface treatment method for coating metal materials with resin, which is characterized by roughening the surface beforehand.