JP2632928B2 - 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 the case of this method, in order to secure the adhesion between the aluminum material and the resin, it is necessary to remove the printing resist after the etching as described above, so that the number of steps is large and the operation is troublesome. . Also, since the mask portion on which the resist is printed is not necessarily etched,
When the fluororesin is coated after the removal of the resist, there is a problem that the adhesion between the aluminum material and the resin is extremely poor in this portion.

In view of the above, the present invention simplifies the undercoating process by omitting the step of removing the printing resist in the undercoating process employing chemical or electrical etching, and allows the non-etched portion of the aluminum material and the resin to be removed. An object of the present invention is to provide a base treatment method capable of significantly improving adhesion.

In order to achieve the above object, the undercoating method according to the present invention prints an etching resist in a predetermined pattern on a surface to be coated with a fluororesin to form a mask portion and a non-mask portion by the resist. Then, in the base treatment for etching the non-mask portion, an ink having a primer function for coating a fluororesin is used as the resist printing ink.

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.

The surface to be coated with the resin is then preferably roughened. This surface roughening is generally performed 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 preferably 1 to 10 μm (Rmax). The reason is that if the thickness is less than 1 μm, sufficient adhesion cannot be obtained, and if it exceeds 10 μm, 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.

Printing inks generally comprise a) a vehicle (resin, oil, solvent ink, plasticizer, etc.), b) a colorant (face material), and c) an additive (surfactant, anti-skinning agent, stabilizer, Antifoaming agent). In the present invention, a resist printing ink having a primer function for coating with a fluororesin is used. That is, the resist printing ink according to the present invention contains a resin having a primer function for coating a fluororesin as a resin component of the vehicle.

a) In the vehicle, typical examples of a resin having a primer function for coating a fluororesin include, for example, ethylene tetrafluoride resin (PTFE), other fluororesins, polyamideimide (PAI), and polyether sulfone (PES). And polyphenylene sulfide (PPS). These resins are used alone or in combination of two or more. Siloxane resins, epoxy resins, and the like can be used in combination with the above resins depending on the conditions. However, if the required heat resistance is extremely high, these cannot be used.
When using a combination of one or more of PAI, PES, PPS, siloxane resin and epoxy resin with PTFE, PAI, PES, PPS, siloxane resin and epoxy resin are all adhesion of printing resist to aluminum material Has the effect of improving the
It is mixed with PTFE at a weight ratio of 0.1-9.

Oils and solvents constituting the vehicle are for improving the drying property and printability of the ink.

b) Colorants (pigments) may not be included. When this is used, titanium oxide or another inorganic pigment is used from the viewpoint of heat resistance.

c) Additives are also used to improve the dispersibility and stability of the ink.

Further, in order to improve the adhesion of the printing resist to the aluminum material, a chromate, a phosphate or the like may be added to the ink.

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. The depth of the recess is usually 100 μm, preferably 20 to 50 μm.

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 an 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.

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 aluminum plate (1) was degreased by immersing it for 1 minute in a treatment solution comprising a 5% aqueous solution of sodium hydroxide at 50 ° C.

Next, as shown in FIG. 2, an etching resist (2) was printed in a grid pattern on the surface of the degreased aluminum plate (1) by screen printing. As the printing ink, a white ink containing titanium oxide as a pigment and PTEF and PAI at a ratio of 1: 1 as a vehicle resin was used. The vehicle contains oil, solvent, and various additives in addition to the above resin. This ink has a primer resin for fluororesin coating. The thickness of the grid lines formed by the resist (2) is 0.2 mm, the pitch of the grid lines is 0.5 mm,
The size of the unmasked portion (3) that is not masked by the lattice-shaped resist (2) was 0.5 mm × 0.5 mm.

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

 Thus, a roughened base surface was formed.

Then, as shown in FIG. 4, 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) which had been subjected to the base treatment. Baking was performed at a temperature of 400 ° C. for 10 minutes to form a resin coating layer (5) having a thickness of 30 μm on the surface of the roughened aluminum plate (1).

Example 2 In the printing process on the surface of the aluminum plate (1), the vehicle resin of Example 1 (PTFE and PA) was used as the printing ink.
Instead of I), an ink containing PTFE and PES at a ratio of 1: 1 was used. Otherwise, the procedure was the same as in Example 1.

Example 3 In the printing process of the surface of the aluminum plate (1), the vehicle resin of Example 1 (PTFE and PA
Instead of I), a material containing PTFE and epoxy resin at a ratio of 1: 1 was used. Otherwise, the procedure was the same as in Example 1.

Example 4 In the printing step of the surface of the aluminum plate (1), the vehicle resin of Example 1 (PTFE and PA
Instead of I), an ink containing only PAI was used. Otherwise, the procedure was the same as in Example 1.

Example 5 In the printing process of the surface of the aluminum plate (1), the vehicle resin of Example 1 (PTFE and PA
The one containing PES was used instead of I). Otherwise, the procedure was the same as in Example 1.

Example 6 In the printing process on the surface of the aluminum plate (1), the vehicle resin of Example 1 (PTFE and PA
The one containing PPS was used instead of I). Otherwise, the procedure was the same as in Example 1.

Comparative Example In the printing process of the surface of the aluminum plate (1), a screen printing ink containing a normal vehicle resin having no primer function for coating with a fluororesin was used as a printing ink. Then, the roughened aluminum plate (1) was immersed in a hydrochloric acid solution to remove the resist (2) remaining on the mask portion. Otherwise, the procedure was the same as in Example 1.

Evaluation of Adhesion The resin coating layers formed in Examples 1 to 6 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, in the case of the example using the printing ink having a primer function for fluororesin coating, the peel strength of the resin coating layer is remarkably higher than in the case of the comparative example in which this was not used. large.

Effect of the Invention According to the undercoating method of the present invention, since a resist printing ink having a primer function for coating a fluororesin is used, the step of removing the printing resist is omitted to simplify the undercoating treatment. And the adhesion between the non-etched portion of the aluminum material and the resin can be significantly improved.

[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 4 are diagrams for explaining the method of the present invention in the order of steps. FIG. 3 is a partially enlarged plan view of the aluminum plate after etching resist printing, FIG. 3 is a partially enlarged cross-sectional view of the aluminum plate having resist printing after etching, and FIG. 4 is a surface of the roughened aluminum plate coated with resin. It is a partial expanded sectional view showing a state. (1) ... aluminum plate, (2) ... etching resist, (3) ... non-mask part, (4) ... concave part for resin anchoring,
(5) ... resin coating layer.

Claims (1)

(57) [Claims] In a base treatment for printing a resist pattern on a surface to be coated with a fluororesin in a predetermined pattern to form a mask portion and a non-mask portion with a resist, and then etching the non-mask portion, An undercoating method for resin coating of a metal material, wherein a printing ink having a primer function for coating a fluororesin is used.