Film-forming treatment liquid

Abstract

An object of the present invention is to provide a treatment liquid and a treatment method that are capable of enhancing the corrosion resistance of a metal material. This object is achieved by, after forming a chemical conversion treatment film on the surface of a metal material, forming a film using a film-forming treatment liquid, the treatment liquid comprising: a silicon compound containing at least one member selected from the group consisting of alkoxysilyl, alkoxysilylene, and a siloxane bond; an organometallic compound; and water.

Claims

1. A film formation method comprising step D of applying a film-forming treatment liquid to a metal material having a silicic acid conversion treatment film, and step C of applying a silicic acid conversion treatment liquid to a metal material before step D to obtain the metal material having a silicic acid conversion treatment film, (a) the film-forming treatment liquid comprising: a silicon compound comprising a resin, wherein the resin comprises at least one member selected from the group consisting of alkoxysilyl, alkoxysilylene, and a siloxane bond, and wherein the resin has a weight average molecular weight of 11000 to 200000; a non-silicon resin, wherein the non-silicon resin is selected from the group consisting of epoxy resins, urethane resins, polyester resins and melamine resins; an organometallic compound; and water, and (b) the silicic acid conversion treatment liquid comprising at least one silicic acid compound selected from the group consisting of lithium silicate, sodium silicate, potassium silicate, ammonium silicate, choline silicate, calcium silicate, magnesium silicate, and hexafluorosilicic acid, (c) the silicate ion concentration in the silicic acid conversion treatment liquid is 10 g/L to 700 g/L.

2. The formation method according to claim 1, further comprising step A of etching the surface of the metal material before step C.

3. The formation method according to claim 2, further comprising step B of desmutting the metal material between step A and step C.

4. The formation method according to claim 1, further comprising step E of curing after step D.

5. The formation method according to claim 4, wherein the curing is a heat treatment.

6. The formation method according to claim 1, wherein a metal of the organometallic compound is at least one member selected from the group consisting of titanium, zirconium, aluminum, and tin.

7. The formation method according to claim 1, wherein the organometallic compound content in the film-forming treatment liquid is 0.01 to 50 parts by mass, relative to 100 parts by mass of the silicon compound.

8. The formation method according to claim 1, wherein the water content in the film-forming treatment liquid is 1 to 100 parts by mass, relative to 100 parts by mass of the silicon compound.

Description

EXAMPLES

(1) The present invention is described below in more detail with reference to Examples. However, the scope of the invention is not limited to these Examples.

Example 1

(2) A mixture of 10 mass % of an acrylic silicone resin (weight average molecular weight: about 20,000, alkoxysilyl content: 40 mass %), 10 mass % of a bisphenol A epoxy resin, and 80 mass % of propylene glycol monoethyl ether was prepared. Subsequently, 3 parts by mass of water and 2 parts by mass of aluminum monoacetylacetonate bis(ethyl acetoacetate) were added to 100 parts by mass of the mixture to prepare a film-forming treatment liquid.

(3) A metal material (magnesium alloy AZ91 substrate (size: 100600.3 mm)) was subjected to a phosphoric acid conversion treatment by immersion for 3 minutes in a 50 g/L aqueous solution of sodium phosphate adjusted to a temperature of 60 C.

(4) The film-forming treatment liquid prepared above was sprayed over the obtained metal material having a phosphoric acid conversion treatment film, and heat treatment was performed at 200 C. for 30 minutes using a dryer to form a film.

Example 2

(5) The procedures were performed in the same manner as in Example 1, except that the metal material was subjected to a zirconium conversion treatment in place of the phosphoric acid conversion treatment. The zirconium conversion treatment was performed by immersing the metal material for 1 minute in a 100 g/L aqueous solution of ammonium zirconium nitrate.

Example 3

(6) The procedures were performed in the same manner as in Example 1, except that the metal material was subjected to a trivalent chromium conversion treatment in place of the phosphoric acid conversion treatment. The trivalent chromium conversion treatment was performed by immersing the metal material for 1 minute in a 100 g/L aqueous solution of trivalent chromium nitrate adjusted to a temperature of 40 C.

Example 4

(7) The procedures were performed in the same manner as in Example 1, except that the metal material was subjected to a silicic acid conversion treatment in place of the phosphoric acid conversion treatment. The silicic acid conversion treatment was performed by immersing the metal material for 3 minutes in a 100 g/L aqueous solution of sodium silicate (water glass No. 3) adjusted to a temperature of 60 C.

Example 5

(8) The procedures were performed in the same manner as in Example 4, except that a film-forming treatment liquid of a different composition was used. The film-forming treatment liquid used in this Example was prepared as follows. A mixture consisting of 20 mass % of silicone resin (produced by Shin-Etsu Chemical Co., Ltd., weight average molecular weight: about 11,000 to 100,000), 10 mass % of a methyltrimethoxysilane oligomer, and 70 mass % of propylene glycol monomethyl ether was prepared. Subsequently, 10 parts by mass of water and 5 parts by mass of titanium diisopropoxy bis(ethyl acetylacetonate) were added to 100 parts by mass of the mixture to prepare a film-forming treatment liquid.

Example 6

(9) The procedures were performed in the same manner as in Example 4, except that the metal material was subjected to etching and desmutting treatments before the silicic acid conversion treatment. The etching treatment was performed by immersing the metal material for 30 seconds in a 100 g/L aqueous solution of nitric acid adjusted to 50 C. The desmutting treatment was performed by immersing the etched metal material for 3 minutes in a 100 g/L aqueous solution of sodium hydroxide adjusted to a temperature of 20 C.

Comparative Example 1

(10) The procedures were performed in the same manner as in Example 1, except that the metal material was degreased with an alkali in place of the phosphoric acid conversion treatment. The alkali degreasing treatment was performed by immersing the metal material in a 10 g/L aqueous solution of sodium hydroxide.

Example 7

(11) The procedures were performed in the same manner as in Example 1, except that an aluminum alloy A5052 substrate (size: 100500.2 mm) was used in place of the magnesium alloy AZ91 substrate as a metal material.

Example 8

(12) The procedures were performed in the same manner as in Example 2, except that an aluminum alloy A5052 substrate (size: 100500.2 mm) was used in place of the magnesium alloy AZ91 substrate as a metal material.

Example 9

(13) The procedures were performed in the same manner as in Example 3, except that an aluminum alloy A5052 substrate (size: 100500.2 mm) was used in place of the magnesium alloy AZ91 substrate, as a metal material.

Example 10

(14) The procedures were performed in the same manner as in Example 4, except that an aluminum alloy A5052 substrate (size: 100500.2 mm) was used in place of the magnesium alloy AZ91 substrate as a metal material.

Example 11

(15) The procedures were performed in the same manner as in Example 5, except that an aluminum alloy A5052 substrate (size: 100500.2 mm) was used in place of the magnesium alloy AZ91 substrate as a metal material.

Example 12

(16) The procedures were performed in the same manner as in Example 6, except that an aluminum alloy A5052 substrate (size: 100500.2 mm) was used in place of the magnesium alloy AZ91 substrate as a metal material, and the etching and desmutting treatment methods were changed accordingly. In this Example, the etching treatment was performed by immersing the metal material for 30 seconds in a 100 g/L aqueous solution of sodium hydroxide adjusted to a temperature of 50 C. The desmutting treatment was performed by immersing the etched metal material for 3 minutes in a 50 g/L aqueous solution of nitric acid adjusted to a temperature of 60 C.

Comparative Example 2

(17) The procedures were performed in the same manner as in Comparative Example 1, except that an aluminum alloy A5052 substrate (size: 100500.2 mm) was used in place of the magnesium alloy AZ91 substrate as a metal material.

Test Example 1: Corrosion Resistance Test

(18) The film-comprising metal materials obtained in Examples 1 to 12 and Comparative Examples 1 and 2 described above were tested for corrosion resistance by a hot-water immersion test (immersed in 100 C. hot water). Each film-comprising metal material was immersed in 100 C. hot water. The time from the start of the immersion until the rusting area accounted for 10% of the surface area of the film-comprising metal material was measured. Table 4 shows the test results.

(19) TABLE-US-00001 TABLE 1 Corrosion resistance test results Metal (Rust development Pretreatment material time) Example 1 Phosphoric acid Magnesium 3 hours conversion alloy treatment Example 2 Zirconium 9 hours conversion treatment Example 3 Trivalent chromium 9 hours conversion treatment Example 4 Silicic acid 12 hours conversion treatment Example 5 Silicic acid 12 hours conversion treatment Example 6 Etching treatment, 24 hours Desmutting treatment, stilicic acid conversion treatment Comparative Degreasing 1 hours Example 1 treatment Example 7 Phosphoric acid Aluminum 36 hours conversion alloy treatment Example 8 Zirconium 48 hours conversion treatment Example 9 Trivalent chromium 48 hours conversion treatment Example 10 Silicic acid 48 hours conversion treatment Example 11 Silicic acid 48 hours conversion treatment Example 12 Etching treatment, 96 hours Desmutting treatment, Silicic acid conversion treatment Comparative Degreasing 24 hours Example 2 treatment

(20) The above results clearly show that forming a film by application of the treatment liquid of the present invention to a metal material having a chemical conversion treatment film can enhance the corrosion resistance.