CONVERSION-COATED METAL PLATE, SURFACE-TREATED METAL PLATE, COMPOSITE MEMBER, AND METHOD FOR PRODUCING CONVERSION-COATED METAL PLATE

Abstract

According to one aspect of the present invention, there is provided a chemical conversion coated metal sheet including a metal substrate and a chemical conversion coating film laminated on at least one surface of the metal substrate, in which the chemical conversion coating film contains a water-soluble resin, and a lubricant having carbon-oxygen bonds; a thickness of the chemical conversion coating film is 0.2 to 1m; and the lubricant includes 1 atom % or more of carbon atoms configuring the carbon-oxygen bonds relative to a total of carbon atoms contained in the lubricant.

Claims

1. A chemical conversion coated metal sheet, comprising a metal substrate and a chemical conversion coating film laminated on at least one surface of the metal substrate, wherein the chemical conversion coating film contains a water-soluble resin, and a lubricant having carbon-oxygen bonds; a thickness of the chemical conversion coating film is 0.2 to 1 m; and the lubricant includes 1 atom % or more of carbon atoms configuring the carbon-oxygen bonds relative to a total of carbon atoms contained in the lubricant.

2. The chemical conversion coated metal sheet according to claim 1, wherein the lubricant is a polyolefin wax.

3. The chemical conversion coated metal sheet according to claim 1, wherein the water-soluble resin is at least one of a water-soluble urethane resin and a water-soluble acrylic resin.

4. The chemical conversion coated metal sheet according to claim 1, wherein the chemical conversion coating film further contains a water-based resin other than the water-soluble resin.

5. A surface-treated metal sheet, comprising the chemical conversion coated metal sheet according to claim 1 and an adhesive layer disposed on a part or a whole of a surface of the chemical conversion coating film in the chemical conversion coated metal sheet.

6. A composite member, comprising the surface-treated metal sheet according to claim 5 and a resin layer disposed on the adhesive layer in the surface-treated metal sheet.

7. The composite member according to claim 6, wherein the resin layer contains a polypropylene resin.

8. A method for producing the chemical conversion coated metal sheet according to claim 1, the method comprising: forming the chemical conversion coating film by applying a chemical conversion coating film-forming coating liquid containing the water-soluble resin and the lubricant onto at least one surface of the metal substrate.

Description

EXAMPLES

[0078] Hereafter, the present invention will be described in further detail by way of examples. However, the following examples do not limit the present invention, and it is all encompassed within the scope of the present invention to carry out the present invention by making changes within a range that does not depart from the gist of the present invention. Also, unless specifically mentioned, parts denotes parts by mass, and % denotes mass %.

[0079] First, a method of measurement and evaluation used in the examples will be described below.

[0080] (Corrosion Resistance (Salt Water Spray Test))

[0081] A test piece was cut out from a chemical conversion coated metal sheet obtained by a later-mentioned production method. After the cut edge (edge surface) was sealed with a tape, a salt water spray test (SST) was carried out for 500 hours in accordance with JIS Z 2371(2015), so as to determine a white rust generation ratio. The results are shown in Table 1.

[0082] (Press-Formability (Kinetic Friction Coefficient))

[0083] The kinetic friction coefficient of a chemical conversion coated metal sheet obtained by a later-mentioned production method was measured with use of a kinetic friction coefficient measurement apparatus (HEIDON (registered trademark) 14D manufactured by Shinto Scientific Co., Ltd.). Specifically, a sum of five points located at different measurement sites were subjected to measurement with respect to the same sample (chemical conversion coated metal sheet) under the following conditions, and an average value of a sum of three points excluding the maximum value and the minimum value was determined as the kinetic friction coefficient.

[0084] Sliding surface: 10 mm steel ball

[0085] Sliding speed: 100 mm/min

[0086] Sliding distance: 50 mm

[0087] (Weldability)

[0088] The welding was carried out with use of a portable spot welding machine (UNI-PROD 10 DIGITAL DELUXE manufactured by Daido Kogyo Co., Ltd.). The materials of the electrodes were chromium copper alloy for both of the anode and the cathode, and a tip end of the electrodes has a curved surface of 4 mm. The welding was carried out by partially superposing a non-coated metal sheet and a chemical conversion coated metal sheet obtained by a later-mentioned production method onto each other. Specifically, the chemical conversion coated metal sheet was superposed so as to be in contact with a part of the surface of the non-coated metal sheet, and welding was carried out by applying a load of 30 to 50 kg onto one electrode and pressing the non-coated metal sheet into the chemical conversion coated metal sheet side. The welding current at the time of welding was set to be 3 kA, and the energization time was set to be 0.25 seconds. Here, onto the other electrode, a load of such a degree that the other electrode may not be separated from the chemical conversion coated metal sheet is applied. The evaluation results are shown in Table 1.

[0089] (Adhesiveness (Adhesive Strength))

[0090] In a composite member obtained by a production method described later, the end of the surface-treated metal sheet as viewed in the longitudinal direction and the end of the resin layer as viewed in the longitudinal direction were held with a chuck of a tensile tester in an atmosphere of 25 C. and pulled at a tensile speed of 10 mm/min. The tensile strength at which the resin layer was peeled off from the surface-treated metal sheet was measured, and the obtained value was determined as the adhesive strength. Here, the end of the surface-treated metal sheet as viewed in the longitudinal direction is an end on the side that is not covered with the resin layer, and the end of the resin layer as viewed in the longitudinal direction is an end on the side to which the surface-treated metal sheet is not bonded.

Examples 1 to 3 and Comparative Examples 1 to 5

[Chemical Conversion Coated Metal Sheet]

[0091] A chemical conversion coating film-forming coating liquid was applied onto a surface of a hot-dip galvannealed steel sheet having a thickness of 1.0 mm with use of a bar coater so that the film thickness after drying would be the film thickness shown in Table 1, followed by heating at 100 C. for one minute to obtain a chemical conversion coated metal sheet provided with the chemical conversion coating film. The composition of the chemical conversion coating film-forming coating liquid (the added amount is in terms of solid components) is shown in Table 1. As the water-soluble resin, ELASTRON (registered trademark) MF-25K manufactured by DKS Co., Ltd. was used. As the water-based resin, SUPERFLEX (registered trademark) 170 manufactured by DKS Co., Ltd. was used. As the colloidal silica, SNOWTEX (registered trademark) 40 (having a surface area average particle size of 10 to 20 nm) manufactured by Nissan Chemical Industries, Ltd. was used. As the silane coupling agent, KBM903 (-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. was used. In Examples 1 to 3 and Comparative Examples 1, 2, and 5, a polyethylene wax (Hi-WAX (registered trademark) 800P800PF manufactured by Mitsui Chemicals, Inc.) subjected to a later-mentioned plasma treatment was used as the lubricant. In Comparative Example 4, a polyethylene wax (Hi-WAX (registered trademark) 800PF manufactured by Mitsui Chemicals, Inc.) that had not been subjected to a plasma treatment was used as the lubricant. Here, in Comparative Example 3, the chemical conversion coating film-forming coating liquid does not contain a lubricant. In Comparative Example 5, the chemical conversion coating film-forming coating liquid does not contain a water-soluble resin.

[0092] <Plasma Treatment of Lubricant>

[0093] The plasma treatment of the lubricant was carried out by using a reactive ion etching apparatus (DEM-451T manufactured by Anelva Corporation). An oxygen gas was introduced into the apparatus, and the pressure was set to be 13 Pa. With use of a high-frequency power source having an output of 200 W with 13.56 MHz, a glow discharge was generated, and a plasma treatment was carried out on the lubricant for 3 minutes. Subsequently, the lubricant subjected to the treatment was immersed into distilled water for one hour, followed by drying.

[0094] With use of a Fourier transform infrared spectrophotometer, the ratio of the carbon atoms configuring the carbon-oxygen bonds relative to the carbon atoms contained in the lubricant (ratio of carbon having a carbon-oxygen bond relative to the carbon in the lubricant) was measured from the absorption in a neighborhood of 1750 cm.sup.1 deriving from the carbon-oxygen bonds and the absorption in a neighborhood of 2950 cm.sup.1 deriving from the carbon-hydrogen bonds. In the lubricant subjected to the plasma treatment, the aforementioned ratio was 6 atom %. Here, the lubricant before being subjected to the plasma treatment did not have a carbon-oxygen bond. In other words, in the lubricant before being subjected to the plasma treatment, the aforementioned ratio was 0 atom %.

[0095] [Surface-Treated Metal Sheet and Composite Member]

[0096] UNISTOLE (register& trademark) R-300 manufactured by Mitsui Chemicals, Inc., which was an acid-modified polypropylene adhesive, was applied onto the chemical conversion coating film of each of the chemical conversion coated metal sheets with use of a bar coater so that the film thickness would be 20 m, followed by heating at 220 C. for two minutes to obtain a surface-treated metal sheet provided with an adhesive layer.

[0097] Next, injection molding was carried out with use of an injection molding machine (PNX60 manufactured by Nissei Plastic Industrial Co., Ltd.). First, the above surface-treated metal sheet was cut to a size of 100 mm25 mm and put into a mold. Thereafter, Prime Polypro (registered trademark) V7000 manufactured by Prime Polymer Co., Ltd., which is a polypropylene resin containing 20 mass % of glass fibers, was melted and ejected so as to cover the surface of the adhesive layer, thereby to obtain a composite member provided with a resin layer having a size of 100 mm length25 mm width3 mm thickness. The resin layer and the surface-treated metal sheet were bonded so as to overlap with each other at 12.5 mm length25 mm width. The injection conditions are shown in Table 2.

TABLE-US-00001 TABLE 1 Configuration Chemical conversion coating film Physical properties Water- Silane Film Kinetic Adhesive soluble Water-based Colloidal coupling thickness Salt water friction strength resin Lubricant resin silica agent (m) spray test coefficient Weldability (MPa) Example 1 24.25% 1.5% 24.25% 45% 5% 0.8 5% or less 0.15 Weldable 14.6 Example 2 24.25% 3% 24.25% 0.5 10% 0.15 Weldable 14.7 Example 3 24.25% 3% 24.25% 0.25 20% 0.2 Weldable 15.1 Comparative 24.25% 3% 24.25% 2 5% or less 0.12 Not weldable 13.9 Example 1 Comparative 24.25% 3% 24.25% 0.1 50% 0.28 Weldable 15.2 Example 2 Comparative 25% 25% 0.8 5% or less 0.34 Weldable 14.5 Example 3 Comparative 24.25% 3% (not 24.25% 0.8 10% 0.14 Weldable 9.8 Example 4 subjected to plasma treatment) Comparative 1.5% 48.5% 0.8 40% 0.15 Weldable 14.7 Example 5

TABLE-US-00002 TABLE 2 Injection molding machine PNX60 manufactured by Nissei Plastic Industrial Co., Ltd. Molding machine 100 25 3.0 mm Shape of molded article (Insert side: 0.8 mmt) Cylinder Nozzle 240 temperature Front part 250 ( C.) Central part 250 Rear part 240 Rearmost part 230 Mold temperature ( C.) 45 to 55 Injection Limit pressure (MPa) 40 pressure Holding pressure (MPa) 50 Filling speed (mm/s) 10 Rotation speed of screw (rpm) 80 Back pressure (MPa) 5 Settings Injection pressure-holding time (s) 6.5 Cooling time (s) 25 Intermediate time (s) 0.3 Metering finishing position (mm) 30 V-P switching position (mm) 7.5 Actual Metering (s) 7.38 measurement Packing (s) 2.47 1 cycle (s)

[0098] From Table 1, studies can be made as follows.

[0099] The chemical conversion coated metal sheets according to Examples 1 to 3 satisfying the constitutional requirements of the present invention were excellent in weldability, corrosion resistance, and press-formability. Further, the composite members produced by using the chemical conversion coated metal sheets according to Examples 1 to 3 were excellent in adhesive strength as well. Accordingly, the chemical conversion coated metal sheets according to Examples 1 to 3 were chemical conversion coated metal sheets excellent in press-formability and were chemical conversion coated metal sheets useful as a material to be formed into a composite member excellent in adhesiveness.

[0100] In contrast, the metal sheets other than those described above did not satisfy the constitutional requirements of the present invention, and hence desired characteristics could not be obtained, as will be described in detail in the following.

[0101] In the chemical conversion coated metal sheet according to Comparative Example 1 in which the film thickness was too large, the weldability was poor. On the other hand, in the chemical conversion coated metal sheet according to Comparative Example 2 in which the film thickness was too small, the corrosion resistance and the press-formability were poor.

[0102] In the chemical conversion coated metal sheet according to Comparative Example 3 that did not contain a lubricant, the press-formability was poor. On the ether hand, regarding the chemical conversion coated metal sheet according to Comparative Example 4 containing a lubricant that had not been subjected to a plasma treatment, the adhesiveness of the composite member produced by using the chemical conversion coated metal sheet according to Comparative Example 4 was poor.

[0103] In the chemical conversion coated metal sheet according to Comparative Example 5 that did not contain a water-soluble resin, the corrosion resistance was poor.

[0104] This application is based on Japanese Patent Application No. 2016-069931 filed on Mar. 31, 2016, the contents of which are incorporated in the present application.

[0105] While the present invention has been fully and appropriately described in the above by way of embodiments in order to express the present invention, it is to be recognized that those skilled in the art can readily change and/or modify the embodiments described above. Therefore, it is to be interpreted that the changes or modifications made by those skilled in the art are encompassed within the scope of the claims unless those changes or modifications are at a level that departs from the scope of the claims described in the claims section of the present application.

INDUSTRIAL APPLICABILITY

[0106] According to the present invention, there is provided a chemical conversion coated metal sheet that is excellent in press-formability and that is useful as a material to be formed into a composite member excellent in adhesiveness. Also, a surface-treated metal sheet useful in combining with a resin molded article is provided by using the chemical conversion coated metal sheet. Further, a composite member excellent in adhesiveness is provided by using the surface-treated metal sheet, that is, by producing the composite member using the chemical conversion coated metal sheet.