Foamed resin composite metal panels and resin-coated metal plates

Abstract

To achieve further weight reduction of metal panels without compromising their rigidity. [Solution] The foamed resin composite metal panel of the present invention comprises two resin-coated metal plates and a foamed resin layer provided between the resin-coated metal plates. Each of the resin-coated metal plates has a resin coating layer on both sides of the metal plate. The resin coating layer on the side in contact with the foamed resin layer has a thickness of 8 to 150 μm. In a cross-section of the resin coating layer cut in the thickness direction, a resin phase with a melting point of 100 to 160°C, a surface tension of 30 to 36 mN / m, and an average particle size of 1.0 to 10.0 μm is unevenly distributed in the range from the surface in contact with the foamed resin layer to 5 μm. Furthermore, the area ratio of the resin phase in the above range in the cross-section is 5 to 50%, the average particle size of the bubbles contained in the foamed resin layer is 30 to 200 μm, and the average bulk density of the foamed resin layer is 0.15 to 0.50 g / cm³. 3 That is the case.

Description

[Technical Field]

[0001] This invention relates to foamed resin composite metal panels and resin-coated metal plates. [Background technology]

[0002] As one measure to reduce the weight of building materials, ship floors, and wall materials for vehicles, a laminated lightweight panel has been proposed and is already in practical use, for example, as shown in Patent Document 1 below, in which a foamed resin layer is bonded and laminated between two metal plates as a core layer.

[0003] In the case of resin composite metal panels using foamed resin as described above, if the adhesive strength between the foamed resin and the metal plate is low, there is a possibility that the interface between the foamed resin and the metal plate may delaminate when the panel is subjected to impact or a heavy load. Therefore, when resin composite metal panels using foamed resin are used as materials in places where heavy loads are known to occur (for example, flooring material in the cargo area of ​​an automobile), it is necessary to increase the adhesive strength between the foamed resin and the metal plate. For this reason, various technologies have been proposed for manufacturing resin composite metal panels.

[0004] For example, Patent Document 2 discloses a method for manufacturing a resin composite panel using plated steel sheets as metal sheets. The manufacturing method disclosed in Patent Document 2 describes a method for manufacturing a laminated panel using plated steel sheets that have been plated on both sides, such as zinc plating, and applying a primer or paint to the surface of the plated steel sheet that comes into contact with a rigid foamed urethane resin. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-56121 [Patent Document 2] Japanese Patent Publication No. 2002-144477 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In automotive applications, where further weight reduction of vehicles is expected to be required in the future, if the goal is to further reduce the weight of resin composite metal panels using foamed resin, it is conceivable to reduce the thickness of the metal plate used in the metal panel and to lower the density of the foamed resin layer. Based on the above idea, the inventors diligently conducted research to achieve weight reduction of resin composite metal panels and found that in the method of manufacturing laminated panels by applying a normal primer or paint, as described in Patent Document 2 above, the distribution of bubble particle size in the foamed resin layer tends to vary, and the panel rigidity tends to become uneven. Undesirable is that the impact resistance of the panel decreases when the panel rigidity becomes uneven due to such variation in the distribution of bubble particle size.

[0007] Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to provide a resin-coated metal sheet that can achieve further weight reduction of a metal panel without reducing the rigidity of the metal panel, and a foamed resin composite metal panel using such a resin-coated metal sheet. [Means for solving the problem]

[0008] To solve the above problems, the inventors conducted diligent research and found that the variation in the bubble particle size distribution in the foamed resin layer was caused by the fluidity of the coating applied to the metal plate that serves as the base material during injection molding of the foamed resin layer. Based on this finding, the inventors conducted further research and were able to realize a resin-coated metal plate having a coating that can suppress the variation in the bubble particle size distribution in the foamed resin layer. By using such a resin-coated metal plate, it was possible to further reduce the weight of the foamed resin composite metal panel while maintaining the rigidity of the panel. Based on these findings, the gist of the present invention is as follows:

[0009] (1) The device comprises two resin-coated metal plates and a foamed resin layer containing air bubbles in the layer, wherein each of the two resin-coated metal plates has a resin coating layer on both sides of the base metal plate, the resin coating layer on the side in contact with the foamed resin layer has a thickness of 8 to 150 μm, and in a cross-section of the resin coating layer on the side in contact with the foamed resin layer cut in the thickness direction, the direction from the surface in contact with the foamed resin layer toward the metal plate Within a range of 0 μm to 5 μm in the direction, a resin phase with a melting point of 100 to 160°C, a surface tension of 30 to 36 mN / m, and an average particle size of 1.0 to 10.0 μm is unevenly distributed. Furthermore, the area ratio of the resin phase within the range of 0 μm to 5 μm in the cross-section is 5 to 50%, the average particle size of the bubbles contained in the foamed resin layer is 30 to 200 μm, and the average bulk density of the foamed resin layer is 0.15 to 0.50 g / cm³. 3 This is a foamed resin composite metal panel. (2) The foamed resin composite metal panel according to (1), wherein the foamed resin constituting the foamed resin layer is rigid polyurethane foam. (3) The foamed resin composite metal panel according to (1) or (2), wherein the resin coating layer on the side in contact with the foamed resin layer has a matrix resin constituting the resin coating layer having a melting point of 225°C or higher and a surface tension of 42 to 52 mN / m. (4) The foamed resin composite metal panel according to (3), wherein the absolute value of the difference between the surface tension of the matrix resin and the surface tension of the resin constituting the resin phase is 20 mN / m or less. (5) The foamed resin composite metal panel according to (3), wherein the matrix resin is either a polyester resin or a polyamide resin. (6) The foamed resin composite metal panel according to (1) or (2), wherein the resin phase is composed of at least one of the following resins: polyethylene resin, carboxylic acid-modified polyethylene resin, polypropylene resin, carboxylic acid-modified polypropylene resin, ethylene-propylene copolymer resin, or carboxylic acid-modified ethylene-propylene copolymer resin. (7) The foamed resin composite metal panel according to (1) or (2), wherein the thickness of the foamed resin layer is 3.0 to 48.0 mm. (8) The foamed resin composite metal panel according to (1) or (2), wherein the thickness of the metal plate is 0.1 to 2.0 mm. (9) The foamed resin composite metal panel according to (1) or (2), wherein the overall thickness of the foamed resin composite metal panel is 3.0 to 50.0 mm. (10) A resin-coated metal plate comprising a base metal plate and resin coating layers provided on both sides of the metal plate, wherein the resin coating layer provided on at least one surface of the metal plate has a thickness of 8 to 150 μm, and in a cross section obtained by cutting the resin coating layer in the thickness direction, a resin phase having a melting point of 100 to 160°C and a surface tension of 30 to 36 mN / m, with an average particle size of 1.0 to 10.0 μm, is unevenly distributed within a range of 0 μm to 5 μm from the surface of the resin coating layer along the thickness direction, and furthermore, the area ratio of the resin phase in the range of 0 μm to 5 μm in the cross section is 5 to 50%. (11) The resin-coated metal plate according to (10), wherein the matrix resin constituting the resin coating layer in which the resin phase is unevenly distributed has a melting point of 225°C or higher and a surface tension of 42 to 52 mN / m. (12) The resin-coated metal plate according to (11), wherein the absolute value of the difference between the surface tension of the matrix resin and the surface tension of the resin constituting the resin phase is 20 mN / m or less. (13) The resin-coated metal plate according to (11), wherein the matrix resin is either a polyester resin or a polyamide resin. (14) The resin-coated metal plate according to (10) or (11), wherein the resin phase is composed of at least one of the following resins: polyethylene resin, carboxylic acid-modified polyethylene resin, polypropylene resin, carboxylic acid-modified polypropylene resin, ethylene-propylene copolymer resin, or carboxylic acid-modified ethylene-propylene copolymer resin. (15) The resin-coated metal plate according to (10) or (11), wherein the thickness of the metal plate is 0.1 to 2.0 mm. [Effects of the Invention]

[0010] As described above, according to the present invention, in the foamed resin composite metal panel, it is possible to achieve further weight reduction of the metal panel without reducing the rigidity as the metal panel.

Brief Description of the Drawings

[0011] [Figure 1] It is an explanatory drawing schematically showing the configuration of the resin-coated metal plate according to an embodiment of the present invention. [Figure 2] It is an explanatory drawing for explaining the resin coating layer of the resin-coated metal plate according to the same embodiment. [Figure 3] It is an explanatory drawing for explaining the resin coating layer of the resin-coated metal plate according to the same embodiment. [Figure 4] It is an explanatory drawing schematically showing the configuration of the foamed resin composite metal panel according to the same embodiment.

Modes for Carrying Out the Invention

[0012] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0013] (Regarding the resin-coated metal plate) First, hereinafter, the resin-coated metal plate as a material of the foamed resin composite metal panel according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3.

[0014] (Regarding the overall configuration of the resin-coated metal plate) FIG. 1 is an explanatory drawing schematically showing the configuration of the resin-coated metal plate according to the present embodiment. As schematically shown in FIG. 1, the resin-coated metal plate 10 according to the present embodiment has a metal plate 11 as a base material and resin coating layers provided on both surfaces of the metal plate 11. [[ID=4(3]]

[0015] In the following, for convenience, the resin coating layer that comes into contact with the foamed resin when used as a material for a foamed resin composite metal panel will be referred to as "resin coating layer 13A," and the resin coating layer on the opposite side of resin coating layer 13A (in other words, the resin coating layer on the side corresponding to the outer surface of the foamed resin composite metal panel when it becomes a foamed resin composite metal panel) will be referred to as "resin coating layer 13B."

[0016] [Regarding the metal plate 11] The metal plate 11, which is the base material of the resin-coated metal plate 10 according to this embodiment, is not particularly limited, and various known metal plates can be used. Examples of such metal plates include steel plates, plated steel plates, aluminum plates, stainless steel plates, titanium plates, and the like. Furthermore, the plating layer of the plated steel plate is not particularly limited, and various known plating layers can be applied.

[0017] Among the metal sheets described above, steel sheets, plated steel sheets, and aluminum sheets are particularly preferred because they are superior in terms of processability, strength, rigidity, and manufacturing cost. The strength and elongation of the metal sheet used can be appropriately determined within a range that does not impair the cutability and processability of the resin-coated metal sheet 10.

[0018] Furthermore, from the viewpoint of reducing the weight of the resin-coated metal plate 10, it is preferable that the metal plate 11 used is a so-called thin sheet material. In this embodiment, the thickness of such metal plate 10 (thickness d0 shown in Figure 1) is preferably in the range of 0.1 to 2.0 mm.

[0019] Here, the actual thickness of the thin sheet material is preferably set appropriately within the above range, depending on the characteristics of the metal sheet used.

[0020] For example, when using a steel plate or plated steel plate as the metal plate 11, its thickness is preferably 0.1 mm or more. By making the thickness of the steel plate (including plated steel plate) 0.1 mm or more, it is possible to appropriately prevent localized holes from forming on the surface of the metal plate 11 even when a hard, protruding, heavy object falls onto the resin-coated metal plate 10 or the foamed resin composite metal panel made from such resin-coated metal plate 10. The thickness of such steel plate (including plated steel plate) can be appropriately determined according to the strength, rigidity, and other characteristics required for the area where the foamed resin composite metal panel made from such resin-coated metal plate 10 is applied. Furthermore, the thickness of the steel plate (including plated steel plate) as the base material for the resin-coated metal plate 10 is usually preferably one-tenth or less of the total thickness of the foamed resin composite metal panel, and at most about 1.0 mm or less.

[0021] Furthermore, when using an aluminum plate as the metal plate 11, its thickness is preferably 0.2 mm or more and 2.0 mm or less. By keeping the thickness of the aluminum plate used as the metal plate 11 within the above range, it is possible to achieve weight reduction while suppressing a decrease in the rigidity of the resin-coated metal plate 10.

[0022] Furthermore, when using a stainless steel plate as the metal plate 11, its thickness is preferably 0.1 mm or more and 0.8 mm or less, and when using a titanium plate as the metal plate 11, its thickness is preferably 0.1 mm or more and 0.8 mm or less.

[0023] Furthermore, in order to confirm the thickness of the metal plate 11 as described above, from the state in which it has become a resin-coated metal plate 10, the following procedure should be followed. That is, the resin-coated metal plate 10 should be immersed in boiling hydrogen peroxide water to peel off the resin coating layer (usually the resin coating layer peels off within 30 minutes), and the thickness of the metal plate 11 after the resin coating layer has been peeled off should be measured with a micrometer. Alternatively, in order to confirm the thickness of the metal plate 11 from the state in which a foamed resin composite metal panel has been manufactured using the resin-coated metal plate 10, a test piece approximately 25 mm wide x 150 mm long should be cut from the foamed resin composite metal panel using a high-speed precision cutter or the like, the metal plate should be peeled off the test piece, and the remaining foamed resin layer should be removed together with the coating resin by immersing it in boiling hydrogen peroxide water, and then the thickness of the metal plate 11 should be measured with a micrometer in the same manner as described above.

[0024] Furthermore, various surface treatments may be applied to the surface of the metal plate 11 as described above. For example, a treatment film layer (not shown) containing inorganic hydrated oxides or inorganic oxides may be provided for the purpose of further improving the adhesion of the resin coating layers 13A and 13B described later. Furthermore, for the purpose of improving adhesion, a metal plating layer (not shown) of the same type as the metal elements contained in such inorganic hydrated oxides or inorganic oxides may be provided below such treatment film layer (not shown).

[0025] Examples of the inorganic hydrated oxides and inorganic oxides mentioned above include chromium hydrated oxide, zirconium hydrated oxide, titanium hydrated oxide, tungsten hydrated oxide, nickel hydrated oxide, cerium hydrated oxide, silica, and the like. By providing a treated coating layer containing one or more of these compounds, the adhesion of the resin-coated metal plate 10 can be further improved.

[0026] [Regarding the resin coating layer 13A] Next, the resin coating layer 13A of the resin-coated metal plate 10 according to this embodiment will be described in detail with reference to Figures 1 to 3. Figures 2 and 3 are explanatory diagrams illustrating the resin coating layer 13A of the resin-coated metal plate according to this embodiment.

[0027] As mentioned earlier, the resin coating layer 13A according to this embodiment is a resin coating layer located on the side that comes into contact with the foamed resin when the resin-coated metal plate 10 is used as a material for a foamed resin composite metal panel. As schematically shown in Figure 2, this resin coating layer 13A comprises a matrix resin 101 that constitutes the resin coating layer 13A and a resin phase 103 that exists within the matrix resin 101.

[0028] In the resin coating layer 13A according to this embodiment, the resin phase 103 is not uniformly dispersed in the matrix resin 101, but rather is unevenly distributed on the surface side of the resin coating layer 13A (the surface side opposite to the metal plate 11), as will be described in detail below. Furthermore, this resin phase 103 has a specific melting point, surface tension, and average particle size, as will be described in detail below.

[0029] In this embodiment, the resin-coated metal plate 10 having the resin coating layer 13A is used as the material for a foamed resin composite metal panel. When a foamed resin layer is formed on the surface of the resin coating layer 13A, the foamed resin layer is formed by injecting liquid foamed resin raw material into a mold and curing the resin raw material.

[0030] Here, the curing reaction that proceeds with the formation of the foamed resin layer is an exothermic reaction. Therefore, in conventionally used resin-coated metal plates, there was a possibility that the coating film would soften due to this heat generation. When the coating film softens, it deforms as a result of the softening, blocking the flow of the foamed resin raw material. As a result, the bubbles generated during the curing reaction aggregate and become coarser. This leads to variations in bubble diameter and variations in the density of the foamed resin layer, which reduces the rigidity of the panel.

[0031] However, in the resin coating layer 13A according to this embodiment, the presence of the resin phase 103 in specific locations makes it possible to prevent softening of the resin coating layer 13A while increasing the fluidity of the foamed resin with the resin phase 103. As a result, it is possible to prevent the coarsening of bubbles generated in the foamed resin, and to prevent a decrease in the rigidity of the manufactured foamed resin composite metal panel.

[0032] Regarding the thickness of the resin coating layer 13A: First, the thickness of the resin coating layer 13A according to this embodiment (thickness d1 in Figure 1) will be explained. In the resin coating layer 13A according to this embodiment, its thickness d1 is in the range of 8 to 150 μm. If the thickness of the resin coating layer 13A is less than 8 μm, the resin phase 103 will protrude excessively from the surface of the resin coating layer 13A, which is undesirable because it reduces adhesion with the foamed resin when manufacturing the foamed resin composite metal panel. By making the thickness of the resin coating layer 13A 8 μm or more, it is possible to prevent excessive protrusion of the resin phase 103 from the surface and ensure adhesion with the foamed resin. The thickness of the resin coating layer 13A is preferably 10 μm or more, and more preferably 12 μm or more.

[0033] On the other hand, if the thickness of the resin coating layer 13A exceeds 150 μm, when the foamed resin raw material is injected into the mold during the manufacturing of the foamed resin composite metal panel, the flow resistance of the foamed resin raw material becomes too large, resulting in localized accumulation of the foamed resin raw material. This makes it easier for the generated bubbles to aggregate and enlarge, reducing the rigidity of the manufactured foamed resin composite metal panel. From this viewpoint, the thickness of the resin coating layer 13A should be 150 μm or less. Preferably, the thickness of the resin coating layer 13A is 100 μm or less, and more preferably 50 μm or less.

[0034] To confirm the thickness of the resin coating layer 13A as described above, from the state in which the resin-coated metal plate 10 has been formed, the resin-coated metal plate 10 can be cross-section-embedded and polished, and the thickness of the coating resin can be measured with an optical microscope.

[0035] Regarding resin phase 103: The resin phase 103 present in the resin coating layer 13A according to this embodiment functions as a wax to ensure the fluidity of the foamed resin raw material when manufacturing a foamed resin composite metal panel. The resin phase 103 will be described in detail below.

[0036] ◇Regarding the average particle size of resin phase 103 First, the average particle size of the resin phase 103 present in the resin coating layer 13A according to this embodiment will be described. In the resin coating layer 13A according to this embodiment, the average particle size of the resin phase 103 is in the range of 1.0 to 10.0 μm.

[0037] When the average particle size of the resin phase 103 is less than 1.0 μm, the surface of the resin phase 103 is less likely to appear on the surface of the coating resin layer. This makes it difficult to lower the surface tension of the coating resin layer, increasing the flow resistance of the foamed resin raw material and making it easier for the bubble size to increase, which is undesirable. When the average particle size of the resin phase 103 is 1.0 μm or more, the surface of the resin phase 103 is more likely to appear on the surface of the coating resin layer. This lowers the surface tension of the coating resin layer, reducing the flow resistance of the foamed resin raw material. This ensures the fluidity of the foamed resin raw material and makes it possible to refine the bubbles in the foamed resin when manufacturing foamed resin composite metal panels. The average particle size of the resin phase 103 is preferably 2.0 μm or more, and more preferably 3.0 μm or more.

[0038] On the other hand, if the average particle size of the resin phase 103 exceeds 10.0 μm, the surface of the resin phase 103 tends to protrude from the surface of the coated resin layer, causing the surface tension of the coated resin layer to drop too low, which is undesirable because it tends to reduce the adhesion between the resin-coated metal plate and the foamed resin layer. By making the average particle size of the resin phase 103 1.0 μm or more, it is possible to improve the fluidity of the foamed resin raw material, suppress the enlargement of air bubbles in the foamed resin layer, and improve the adhesion between the resin-coated metal plate and the foamed resin layer after panel molding. The average particle size of the resin phase 103 is preferably 8.0 μm or less, and more preferably 5.0 μm or less.

[0039] ◇Regarding the melting point and surface tension of the resin constituting the resin phase 103 Next, the resin constituting the resin phase 103 according to this embodiment has a melting point in the range of 100 to 160°C and a surface tension in the range of 30 to 36 mN / m.

[0040] If the melting point of the resin constituting the resin phase 103 is less than 100°C, the resin phase 103 will soften and flow quickly due to the heat generated when the foaming resin raw material is injected, making it more likely to detach from the surface of the coating resin and reducing the effect of promoting the fluidity of the foaming resin raw material, which is undesirable. By setting the melting point of the resin constituting the resin phase 103 to 100°C or higher, it is possible to suppress the premature detachment of the resin phase 103 from the surface of the coating resin when the foaming resin raw material is injected, thereby ensuring the fluidity of the foaming resin raw material and enabling the miniaturization of bubbles in the foamed resin when manufacturing foamed resin composite metal panels. The melting point of the resin constituting the resin phase 103 is preferably 115°C or higher, and more preferably 120°C or higher.

[0041] On the other hand, if the melting point of the resin constituting the resin phase 103 exceeds 160°C, the timing at which the resin phase 103 begins to melt will be delayed when manufacturing the foamed resin composite metal panel. As a result, it will be impossible to ensure sufficient fluidity of the foamed resin raw material when manufacturing the foamed resin composite metal panel. Therefore, by setting the melting point of the resin constituting the resin phase 103 to 160°C or lower, the resin phase 103 will melt sufficiently from an early stage of the curing reaction when forming the foamed resin layer, making it possible to ensure sufficient fluidity of the foamed resin raw material. The melting point of the resin constituting the resin phase 103 is preferably 155°C or lower, and more preferably 140°C or lower.

[0042] Furthermore, the surface tension of the resin constituting the resin phase 103 is in the range of 30 to 36 mN / m. If the surface tension of the resin constituting the resin phase 103 is less than 30 mN / m, the interfacial strength between the matrix resin 101 constituting the resin coating layer 13A and the resin phase 103 present in the matrix resin 101 is weak. As a result, the resin phase 103 tends to detach prematurely from the surface of the coating resin when the foamed resin raw material is injected, reducing the effect of promoting the fluidity of the foamed resin raw material, which is undesirable. By making the surface tension of the resin constituting the resin phase 103 30 mN / m or higher, it is possible to ensure the fluidity of the foamed resin raw material and to make the bubbles in the foamed resin finer. Preferably, the surface tension of the resin constituting the resin phase 103 is 31 mN / m or higher, and more preferably 32 mN / m or higher.

[0043] On the other hand, if the surface tension of the resin constituting the resin phase 103 exceeds 36 mN / m, the effect of reducing the surface tension of the coating resin layer surface is small, and the effect of suppressing the flow resistance of the foamed resin raw material is small, which is undesirable because the bubble particle size tends to increase. By making the surface tension of the resin constituting the resin phase 103 36 mN / m or less, it becomes possible to refine the bubble particle size while ensuring the effect of reducing the surface tension of the coating resin layer surface, and it becomes possible to ensure the fluidity of the foamed resin raw material when manufacturing foamed resin composite metal panels. The surface tension of the resin constituting the resin phase 103 is preferably 35 mN / m or less, and more preferably 34 mN / m or less.

[0044] ◇Regarding the uneven distribution of the resin phase 103 in the resin coating layer 13A Next, we will explain the uneven distribution of the resin phase 103 within the resin coating layer 103. In the resin-coated metal plate 10 according to this embodiment, as schematically shown in Figure 2, in a cross-section obtained by cutting the resin coating layer 13A in the thickness direction, the resin layer 103 described above is unevenly distributed within a range of 0 μm to 5 μm (within the range from position P1 to position P2 in Figure 2) in the direction toward the metal plate 11 from the surface in contact with the foamed resin layer in the foamed resin composite metal panel. Furthermore, within this range of 0 μm to 5 μm (within the range from position P1 to position P2 in Figure 2), the area ratio of the resin phase is 5 to 50%.

[0045] As schematically shown in Figure 2, the presence of a large amount of the resin phase 103, which is unevenly distributed within the range from position P1 to position P2, allows a sufficient amount of resin phase 103 to contribute to the flow of the foamed resin raw material, making it possible to refine the bubbles in the foamed resin.

[0046] Here, if the area ratio of the resin phase 103 within the above range is less than 5%, there is too little resin phase 103 present in the range from position P1 to position P2, making it impossible to ensure the fluidity of the foamed resin raw material during the manufacture of the foamed resin composite metal panel. The area ratio of the resin phase 103 within the above range is preferably 10% or more, and more preferably 15% or more.

[0047] On the other hand, if the area ratio of the resin phase 103 within the above range exceeds 50%, there will be too much resin phase 103 within the range from position P1 to position P2, making it impossible to ensure adhesion between the resin coating layer 13A and the foamed resin. Therefore, the area ratio of the resin phase 103 within the above range should be 50% or less. Preferably, the area ratio of the resin phase 103 within the above range is 40% or less, and more preferably 35% or less.

[0048] Furthermore, in the resin coating layer 13A according to this embodiment, when considering a cross-section obtained by cutting the resin coating layer 13A in the thickness direction, as illustrated in Figure 2, it is preferable that the area ratio of the resin phase is 4% or less within a range of 0 μm to 5 μm (within the range from position P3 to position P4 in Figure 2) in the direction toward the surface of the resin coating layer 13A from the surface in contact with the metal plate 11.

[0049] If the area ratio of the resin phase 103 exceeds 4% within the range from position P3 to position P4, the amount of resin phase 103 in that range becomes too large, making it difficult to ensure adhesion between the metal plate 11 and the resin coating layer 13A. The area ratio of the resin phase 103 within the range from position P3 to position P4 is more preferably 3% or less, and even more preferably 2% or less.

[0050] Furthermore, the area ratio of the resin phase 103 within the range from position P3 to position P4 is better as low as possible, and there is no specific lower limit. The area ratio of the resin phase 103 within the range from position P3 to position P4 may be 0%.

[0051] ◇Regarding the measurement methods for the above characteristics Here, the uneven distribution of the resin phase 103 as described above can be measured by preparing a cross-sectional polished sample obtained by cutting the resin-coated metal plate 10 at an arbitrary position in the thickness direction, and observing this cross-sectional polished sample with a scanning electron microscope (SEM). More specifically, the prepared cross-sectional polished sample is ultrasonically treated in o-dichlorobenzene at 150°C for 30 minutes to dissolve the resin phase 103 in the resin coating layer 13A. As a result, the areas where the resin phase 103 was present in the cross-sectional polished sample become voids, making it easy to determine the position of the resin phase 103. After this treatment, carbon is vacuum-deposited onto the surface of the cross-sectional polished sample, and observation is performed with an SEM at a magnification of 5000x.

[0052] In the cross-sectionally polished sample after the above processing, observe a region of 5 μm in the depth direction from the interface and 25 μm in the direction parallel to the interface at any three locations on the surface side of the resin coating layer 13A, and identify the area of ​​voids using functions implemented in the SEM. This allows you to calculate the area ratio of voids within the region of interest. Perform such observations and average the obtained area ratios. The average value obtained in this way can be treated as the area ratio of the resin phase 103 within the range from position P1 to position P2.

[0053] In the resin-coated metal plate 10 according to this embodiment, depending on the thickness of the resin coating layer 13A and the average particle size of the resin phase 103, it is possible that the resin phase 103 located near the surface of the resin coating layer 13A may form a protrusion, as schematically shown in Figure 3. In this case, for the position P1 described above, the position of the surface of the resin coating layer 13A in the area where the resin phase 103 does not exist can be treated as the reference plane.

[0054] Furthermore, each SEM image obtained from the above observations is binarized to determine the number of resin phases 103 and the total area of ​​all resin phases 103 (more specifically, the number and total area of ​​pores corresponding to the resin phases 103). Then, the average area per resin phase 103 is calculated by dividing the total area of ​​the resin phases 103 by the number of resin phases 103. This average area is then used to calculate the average particle size of the resin phases 103 using the formula for the area of ​​a circle. The average particle sizes calculated from the three resulting microscope images are then averaged. The average value obtained in this way can then be used as the average particle size of the resin phases 103.

[0055] Similarly, in the cross-sectional polished sample after acetone treatment, a 17 μm × 25 μm area corresponding to the interface between the resin coating layer 13A and the metal plate 11 is observed, and the area of ​​voids is identified using functions implemented in the SEM. This allows the area ratio of voids in the 17 μm × 25 μm area of ​​interest to be calculated. Such observations are performed in any three locations, and the obtained area ratios are averaged. The average value obtained in this way can then be treated as the area ratio of the resin phase 103 within the range from position P3 to position P4.

[0056] Furthermore, the melting point of the resin constituting the resin phase 103 described above is determined by immersing the resin-coated metal plate 10 in boiling hydrogen peroxide water to peel off and extract the resin coating layer 13A, and analyzing a film sample of about 5 to 10 mg using differential scanning calorimetry (DSC). In this differential scanning calorimetry, an endothermic peak of melting separate from the melting point of the matrix resin phase appears in the temperature range of 100°C to 160°C, and this value can be taken as the melting point of the resin constituting the resin phase 103. For example, a commercially available differential scanning calorimeter (e.g., DSC7030 manufactured by Hitachi High-Tech Science Corporation) can be used, the obtained sample can be sealed in an aluminum pan, and measurements can be taken in the range of 50 to 350°C at a heating rate of 10°C / min.

[0057] ◇Specific examples of resins constituting the resin phase 103 The resin phase 103 exhibiting the properties described above is preferably composed of at least one of the following resins: polyethylene resin, carboxylic acid-modified polyethylene resin, polypropylene resin, carboxylic acid-modified polypropylene resin, ethylene-propylene copolymer resin, or carboxylic acid-modified ethylene-propylene copolymer resin. By using such resins, it becomes easier to realize the resin phase 103 having the above-described properties.

[0058] In this case, to identify the resin used as the resin phase 103 from the state of an already manufactured resin-coated metal plate 10, the resin type can be identified by polishing IR analysis, Raman spectroscopy, or the like, at the portion of the cross-section of the resin coating layer 13A of the resin-coated metal plate 10 that corresponds to the resin phase 103.

[0059] ≪About Matrix Resin 101≫ Next, the matrix resin 101 in the resin coating layer 13A according to this embodiment will be described in detail. The matrix resin 101 is the main resin constituting the resin coating layer 13A. It is preferable to use a matrix resin 101 that has polar groups capable of hydrogen bonding in the polymer chains constituting the resin. By using a resin with such polar groups, it is possible to further improve the adhesion between the metal plate 11 and the resin coating layer 13A.

[0060] Furthermore, it is preferable that the resin coating layer 13A according to this embodiment is less prone to softening even when the resin-coated metal plate 10 having the resin coating layer 13A according to this embodiment is used as a material for a foamed resin composite metal panel and is exposed to the reaction heat generated when the foamed resin layer is formed on the surface of the resin coating layer 13A. This makes it possible to further suppress the softening of the resin coating layer 13A and the increase in viscosity caused by such reaction heat.

[0061] More specifically, the melting point of the matrix resin 101 used in the resin coating layer 13A is preferably 225°C or higher. This makes it possible to further suppress the occurrence of bubble coarsening, uneven bubble particle size, and uneven bubble density when forming the foamed resin layer of the foamed resin composite metal panel. The melting point of the matrix resin 101 is more preferably 227°C or higher, and even more preferably 228°C or higher. On the other hand, there is no particular upper limit for the melting point of the matrix resin 101, but in practice it is approximately 265°C.

[0062] Furthermore, in the resin coating layer 13A according to this embodiment, the surface tension of the matrix resin 101 is preferably in the range of 42 to 52 mN / m. By having a surface tension of 42 mN / m or more for the matrix resin 101, the adhesive strength between the resin coating layer 13A and the foamed resin can be further improved. This makes it possible to further prevent the resin-coated metal plate 10 from peeling off and the foamed resin composite metal panel from buckling, even when a heavy object is placed on the foamed resin composite metal panel. The surface tension of the matrix resin 101 is more preferably 43 mN / m or more, and even more preferably 44 mN / m or more.

[0063] On the other hand, by making the surface tension of the matrix resin 101 52 mN / m or less, a decrease in the interfacial strength between the matrix resin 101 and the resin phase 103 can be prevented. The surface tension of the matrix resin 101 is more preferably 50 mN / m or less, and even more preferably 48 mN / m or less.

[0064] In this case, to determine the melting point and surface tension of the matrix resin 101 from the state of the resin-coated metal plate 10, a sample of about 5 to 10 mg can be taken from the portion of the cross-section of the resin coating layer 13A of the resin-coated metal plate 10 that corresponds to the matrix resin 101, and measured in the same manner as the resin phase 103.

[0065] The resin used as the matrix resin 101 according to this embodiment may be a thermoplastic resin or a thermosetting resin. Examples of such resins include polyester resins and polyamide resins. In particular, it is preferable to use a polyester resin (homoPET (polyethylene terephthalate resin), PET-IA (polyethylene terephthalate-isophthalate copolymer resin), PET-PBT (polyethylene terephthalate-polybutylene terephthalate copolymer resin), and a blend of these resins. This is because these resins have a high melting point and excellent fusion properties, adhesion strength, and corrosion resistance with the metal plate 11.

[0066] Regarding the difference in surface tension between the matrix resin 101 and the resin phase 103: In the resin coating layer 13A according to this embodiment, the absolute value of the difference between the surface tension of the matrix resin 101 and the surface tension of the resin constituting the resin phase 103 is preferably 20 mN / m or less. By making the absolute value of the difference in surface tension 20 mN / m or less, it is possible to make the average particle size of the resin phase 103 in the resin coating layer 13A smaller. This makes it easier to ensure the fluidity of the foamed resin raw material when manufacturing foamed resin composite metal panels. Here, there is no particular lower limit for the absolute value of the difference in surface tension as described above, but it is practically about 10 mN / m.

[0067] The resin coating layer 13A of the resin-coated metal plate 10 according to this embodiment has been described in detail above with reference to Figures 2 and 3.

[0068] [Regarding the resin coating layer 13B] Next, returning to Figure 1, we will describe the resin coating layer 13B of the resin-coated metal plate 10 according to this embodiment.

[0069] In the resin-coated metal plate 10 according to this embodiment, the resin coating layer 13B located on the opposite side of the resin coating layer 13A is not particularly defined, and any known resin can be used to achieve the various properties (e.g., corrosion resistance) required for the outer surface of the foamed resin composite metal panel.

[0070] One application of the foamed resin composite metal panel manufactured using the resin-coated metal plate 10 according to this embodiment is as flooring material for the cargo area of ​​an automobile. In the cargo area of ​​an automobile, carpets or the like are often bonded to the surface of the flooring material. Therefore, considering adhesion to carpets or the like, the surface tension of the resin constituting the resin coating layer 13B is preferably 38 mN / m or more.

[0071] The resin-coated metal plate 10 according to this embodiment has been described in detail above with reference to Figures 1 to 3.

[0072] (Regarding the manufacturing method of resin-coated metal sheets) Next, an example of a method for manufacturing the resin-coated metal plate 10 according to this embodiment, as described above, will be explained.

[0073] <Preparation of metal plate 11> First, a metal plate 11, which will serve as the base material for the resin-coated metal plate 10, is prepared. The method for manufacturing the base material metal plate 11 is not particularly limited and can be manufactured using various known methods. It is preferable to clean the surface of the prepared metal plate 11 by performing a surface cleaning treatment using a solvent such as acetone.

[0074] The metal plate 11 after cleaning may be subjected to various surface treatments as needed. For example, a treated coating layer containing inorganic hydrated oxides or inorganic oxides may be formed by various known methods for the purpose of further improving the adhesion of the resin coating layers 13A and 13B described later.

[0075] <Formation of resin coating layer 13A> Next, a resin coating layer 13A is formed on one surface of the prepared metal plate 11. There is no particular method for forming the resin coating layer 13A, and various known methods can be used, such as coating the metal plate with a water-based or oil-based resin using a roll coater, curtain coater, etc., directly extruding a thermoplastic resin onto the metal plate using a resin extruder and laminating it, or laminating a thermoplastic resin film onto a heated metal plate by pressing it with a heat-resistant rubber roll.

[0076] For example, when coating a metal plate 11 with resin by melt extrusion, one or more types of resin pellets that will become the resin phase 103 can be melt-extruded and dispersed together with the resin pellets of the matrix resin 101 in the surface extruder of a multilayer extruder, or the resin powder that will become the resin phase 103 can be melt-extruded together with the resin of the matrix resin 101 to directly laminate the resin onto the surface of the metal plate 11.

[0077] Furthermore, when forming a resin coating layer 13A by laminating a resin film onto the surface of the metal plate 11, it is preferable to use a method in which the thermoplastic resin film is pressed onto the heated metal plate 11 with a pressure roll coated with heat-resistant rubber. This is because such a method does not result in air bubbles being trapped and also improves the adhesion of the film. The resin film used may be an unstretched film manufactured by a co-extrusion film formation apparatus having a conventional multilayer extruder, or it may be a stretched film manufactured by stretching it longitudinally and transversely and then heat-treating it after multilayer extrusion.

[0078] Here, the above resin film can be manufactured by melt-extruding one or more types of resin pellets that will become the resin phase 103 together with resin pellets of the matrix resin 101 into the surface extruder of a multilayer extruder, or by melt-extruding resin powder that will become the resin phase 103 together with the matrix resin 101.

[0079] Furthermore, in the above method, instead of adding resin pellets or resin powder that will become the resin phase 103 to the matrix resin 101, a masterbatch pellet prepared by pre-mixing and extruding a resin that will become the resin phase 103 into the matrix resin 101 at a high concentration may be used.

[0080] In any of the above methods, the resin that forms the resin phase 103 is one that falls within the melting point and surface tension range described above. Furthermore, it is preferable that the matrix resin 101 also falls within the melting point and surface tension range described above.

[0081] Here, in order to ensure that the average particle size of the resin constituting the resin phase 103 is within the range of 1.0 to 10.0 μm, if a resin powder is used for the resin phase 103, it is sufficient to use a resin with an average particle size within the range of 1.0 to 10.0 μm. Furthermore, when blending resin pellets that will become the resin phase 103 with the matrix resin 101 to form a film, differences in the particle size and dispersion state of the resin that will become the resin phase 103 will occur depending on the shape and rotation speed of the extrusion screw. Therefore, the extrusion conditions should be adjusted so that the average particle size and dispersion state of the resin phase 103 are in the desired state. In addition, when using a masterbatch pellet prepared by kneading and extruding the resin that will become the resin phase 103 at a high concentration with the matrix resin 101, the kneading conditions should be adjusted so that the average particle size of the resin phase 103 in the masterbatch pellet is within the range of 1.0 to 10.0 μm.

[0082] Furthermore, in the manufacturing method described above, if there is a large difference in surface tension between the matrix resin 101 and the resin that will become the resin phase 103, the particle size of the resin phase 103 tends to become larger. Therefore, two or more resins with different surface tensions may be used to form the film together.

[0083] For example, if the matrix resin 101 is a thermoplastic polyester resin and the resin that becomes the resin phase 103 is a resin that does not have polar groups in its molecule, such as polyethylene resin, then under normal melt extrusion conditions, the resin phase 103 is difficult to finely disperse. In such cases, the matrix resin 101 and the resin that becomes the resin phase 103 should be formed or kneaded together with a carboxylic acid-modified polyethylene or the like, which has an intermediate surface tension between the two. This allows the carboxylic acid-modified polyethylene, which has an intermediate surface tension, to cover the surface of the polyethylene resin, which has a low surface tension, and enables the fine dispersion of the polyethylene with a low surface tension in the polyester resin that becomes the matrix phase. For the combination of resins that become the resin phase 103 as described above, the type and amount should be adjusted in conjunction with the kneading conditions so that the average particle size of the resin in the resin phase 103 is within the range of 1.0 to 10.0 μm.

[0084] <Formation of resin coating layer 13B> Next, a resin coating layer 13B is formed on the other surface of the prepared metal plate 11. The method for forming the resin coating layer 13B is not particularly limited, and various known methods can be used, such as coating a metal plate with an aqueous or oil-based resin using a roll coater, curtain coater, etc., directly extruding a thermoplastic resin onto a metal plate using a resin extruder and laminating it, or laminating a thermoplastic resin film onto a heated metal plate by pressing it with a heat-resistant rubber roll.

[0085] Alternatively, the resin coating layer 13A and the resin coating layer 13B may be formed simultaneously.

[0086] The method for manufacturing the resin-coated metal plate 10 according to this embodiment has been described above.

[0087] (Regarding foamed resin composite metal panels) Next, a foamed resin composite metal panel using the resin-coated metal plate 10 according to this embodiment as a material will be described with reference to Figure 4. Figure 4 is a schematic diagram illustrating the configuration of a foamed resin composite metal panel according to this embodiment.

[0088] <About the overall composition of foamed resin composite metal panel 1> As schematically shown in Figure 4, the foamed resin composite metal panel 1 according to this embodiment comprises two resin-coated metal plates 10 and a foamed resin layer 20 containing air bubbles in the layer, provided between these two resin-coated metal plates 10.

[0089] Here, the two resin-coated metal plates 10 that constitute the foamed resin composite metal panel 1 are as described above, and are arranged such that the resin coating layer 13A on each resin-coated metal plate 10 is in contact with the foamed resin layer 20.

[0090] As explained above, the two resin-coated metal plates 10 that make up the foamed resin composite metal panel 1 are as described, so a detailed explanation will be omitted below.

[0091] Furthermore, the overall thickness of the foamed resin composite metal panel 1 (thickness dT in Figure 4), as shown in Figure 4, is preferably within the range of 3.0 to 50.0 mm. A more detailed thickness can be determined as appropriate according to various conditions such as the load-bearing capacity and installation space required for the area where the foamed resin composite metal panel 1 is used.

[0092] For example, if the thickness of the metal plate 11 of the resin-coated metal plate 10 is 0.5 mm or less, the overall thickness dT of the foamed resin-metal composite panel is preferably around 3.0 to 10.0 mm from the viewpoint of panel rigidity and weight reduction. If the thickness of the metal plate 11 of the resin-coated metal plate 10 exceeds 0.5 mm, there is no particular upper limit to the overall thickness dT of the foamed resin-metal composite panel 1, but for typical automobile luggage boards, etc., it is possible to ensure sufficient load-bearing capacity by making it 50.0 mm or less.

[0093] The overall thickness dT of the foamed resin-metal composite panel 1 described above can be measured using a micrometer or calipers.

[0094] <Regarding the foamed resin layer 20> The foamed resin layer 20 according to this embodiment is a layer located between two resin coating layers 13A, and is composed of foamed resin 201 with air bubbles 203 within it.

[0095] [Regarding the average particle size of bubble 203] In the foamed resin layer 20 according to this embodiment, the average particle size of the bubbles 203 contained in the layer is in the range of 30 to 200 μm. If the average particle size of the bubbles 203 contained in the foamed resin layer 20 is less than 30 μm, unevenness in the density of the bubbles 203 is likely to occur, resulting in an uneven distribution of stiffness within the foamed resin composite metal panel 1, which is undesirable. By making the average particle size of the bubbles 203 contained in the foamed resin layer 20 30 μm or more, unevenness in the density of the bubbles 203 can be suppressed, and the stiffness required for the foamed resin composite metal panel 1 can be secured. Preferably, the average particle size of the bubbles 203 contained in the foamed resin layer 20 is 50 μm or more, and more preferably 100 μm or more.

[0096] On the other hand, if the average particle size of the bubbles 203 contained in the foamed resin layer 20 exceeds 200 μm, the rigidity of the foamed resin composite metal panel 1 decreases, making the panel more prone to bending when a heavy object is placed on it, and potentially causing the panel to buckle, which is undesirable. By making the average particle size of the bubbles 203 contained in the foamed resin layer 20 200 μm or less, it is possible to ensure the rigidity required for the foamed resin composite metal panel 1. The average particle size of the bubbles 203 contained in the foamed resin layer 20 is preferably 180 μm or less, and more preferably 150 μm or less.

[0097] Here, the average particle size of the bubbles 203 contained in the foamed resin layer 20 can be determined as follows. First, regarding the foamed resin composite metal panel 1 of interest, when the foamed resin composite metal panel 1 is viewed from above in a plan view, three locations are cut in the thickness direction at the 1 / 4, 1 / 2, and 3 / 4 positions in the width direction at the center of the panel in the vertical direction. Test pieces measuring 15 mm × 10 mm are then cut and collected using a high-speed precision cutting machine. Subsequently, cross-sectional embedded polished samples are prepared using each of the obtained test pieces. For each of the obtained cross-sectional embedded polished samples, three locations on the cross-section of the foamed resin layer (two locations near the interface on the side closer to the resin-coated metal plate, and approximately the center in the thickness direction) are photographed using an optical microscope at a magnification of 200x. The microscopic images of each of the three observed locations are binarized to determine the number of bubbles present and the total area of ​​all bubbles. The average area per bubble is obtained by dividing the obtained total area of ​​bubbles by the number of bubbles, and the average particle size of the bubbles is calculated inversely using the formula for the area of ​​a circle. The average particle size obtained from the nine observed microscope images can be averaged by the number of observed locations, and the resulting average value can be used as the average particle size of bubble 203.

[0098] [Regarding the average bulk density of the foamed resin layer 20] Furthermore, in the foamed resin layer 20 according to this embodiment, the average bulk density of the foamed resin layer 20 is 0.15 to 0.50 g / cm³. 3 It falls within the range. The average bulk density is 0.15 g / cm³. 3 If the average bulk density of the foamed resin layer 20 is less than 0.15 g / cm³, the bubbles 203 become flattened, resulting in the resin walls between the bubbles 203 becoming too thin, and consequently, the strength of the foamed resin layer 20 decreases. This is undesirable because it reduces the rigidity and buckling strength of the foamed resin composite metal panel 1. 3 As a result, the shape of the air bubbles 203 can be made uniform, ensuring the strength of the foamed resin layer 20 and securing the rigidity required for the foamed resin composite metal panel 1. The average bulk density of the foamed resin layer 20 is preferably 0.20 g / cm³. 3 The above is more accurate, and more preferably 0.25 g / cm³ 3 That's all.

[0099] On the other hand, when the average bulk density of the foamed resin layer 20 exceeds 0.50 g / cm 3 , not only will the weight reduction of the foamed resin composite metal panel 1 be insufficient, but also the interval between the bubbles 203 in the foamed resin layer 20 will become wider, making the bubbles likely to grow and the distribution likely to vary. As a result, the distribution of rigidity within the panel is likely to become non-uniform, which is not preferable. Also, from the perspective of the cost of the foamed resin, it is not preferable. By setting the average bulk density of the foamed resin layer 20 to 0.50 g / cm 3 or less, while suppressing the manufacturing cost, the distribution of the bubbles 203 in the foamed resin layer 20 can be made uniform, the foamed resin composite metal panel 1 can be lightened, and the rigidity required for the panel itself can be ensured. The average bulk density of the foamed resin layer 20 is preferably 0.40 g / cm 3 or less, and more preferably 0.35 g / cm 3 or less.

[0100] Here, the average bulk density of the foamed resin layer 20 can be specified as follows. First, 1) a sample with a size of about 5 cm × 5 cm is cut and collected from the foamed resin composite metal panel using a high-speed precision cutter. 2) Only the resin-coated metal plate 10 is peeled off from the foamed resin composite metal panel sample using a cutter blade to form the foamed resin layer into an accurate rectangular parallelepiped. Next, 3) the length, width, and thickness of the foamed resin layer sample are measured using calipers to obtain the volume of the rectangular parallelepiped. 4) The weight of the foamed resin layer sample is measured using a precision electronic balance. 5) The weight of the foamed resin layer sample is divided by the volume of the foamed resin layer sample to calculate the bulk density of the single foamed resin layer. 6) Such measurements are performed on a plurality of foamed resin layer samples, and the average value of the obtained values is taken as the average bulk density of the foamed resin layer 20.

[0101] In the foamed resin composite metal panel 1 according to this embodiment, the resin coating layer 13A described above is located on the surface of the resin-coated metal plate 10 that is in contact with the foamed resin. As a result, the fluidity of the foamed resin is not impaired when forming the foamed resin layer 20. Consequently, the bubbles generated during the curing reaction of the foamed resin do not become coarse and are distributed uniformly. As a result, the average density of the bubbles 203 and the average bulk density of the foamed resin layer 20 are achieved within the formed foamed resin layer 20, ensuring rigidity throughout the entire panel while further reducing the weight of the panel.

[0102] [Regarding the thickness of the foamed resin layer 20] The thickness (thickness d3 in Figure 4) of the foamed resin layer 20, which has the average particle size of the bubbles 203 as described above and an average bulk density within the above range, is preferably in the range of 3.0 to 48.0 mm. By making the thickness d3 of the foamed resin layer 20 3.0 mm or more, it becomes possible to make the average particle size and distribution state of the bubbles 203 more uniform, and even when the foamed resin composite metal panel 1 is used as a luggage board for an automobile, it is possible to achieve better load-bearing capacity. The thickness d3 of the foamed resin layer 20 is more preferably 4.0 mm or more, and even more preferably 5.0 mm or more.

[0103] On the other hand, by setting the thickness d3 of the foamed resin layer 20 to 48.0 mm or less, it becomes possible to further reduce the weight of the panel while ensuring the rigidity required for the foamed resin composite metal panel 1. The thickness d3 of the foamed resin layer 20 is more preferably 20.0 mm or less, and even more preferably 10.0 mm or less.

[0104] In this case, to determine the thickness d3 of the foamed resin layer 20 from the state of an already manufactured foamed resin composite metal panel, a sample of approximately 5 cm x 5 cm can be cut from the foamed resin composite metal panel using a high-speed precision cutter, the cross-section of the sample can be polished, and the thickness of the foamed resin layer 20 can be measured with calipers.

[0105] [Regarding the foamed resin 201 that constitutes the foamed resin layer 20] The foamed resin 201 constituting the foamed resin layer 20 according to this embodiment can be any known foamed resin, as long as it is cured and foamed using a liquid foamed resin raw material. In particular, it is preferable to use a thermosetting rigid foamed polyurethane resin foam as the foamed resin 201, from the viewpoint of excellent adhesion without the use of adhesive when joining with the resin-coated metal plate 10, high hardness of the formed foamed resin layer, and the ability to increase the volume of air bubbles and easily reduce density.

[0106] As a raw material for the above-mentioned thermosetting rigid polyurethane foam, it is preferable to use a two-component mixed raw material mainly composed of polyol, polyisocyanate, and a foaming agent, from the viewpoint of achieving high hardness after curing.

[0107] In particular, using an ester-based polyol as the polyol mentioned above is preferable because it allows for particularly hardening of the foamed resin layer 20 after curing of the foamed resin 201. Examples of raw materials for such polyols include diol adipate and diethylene glycol adipate triol. If necessary, the hardness may be adjusted using polyether polyol-based raw materials such as propylene glycol and glycerin.

[0108] Examples of the polyisocyanates mentioned above include diphenylmethane isocyanate (MDI) and tolylene diisocyanate (TDI).

[0109] Examples of the foaming agents mentioned above include alternative fluorocarbons (HFCs), water, hydrocarbons such as cyclopentane, and hydrofluoroolefins (HFOs).

[0110] Furthermore, polyurethane catalysts, foaming agents, etc., may be added to the polyol liquid composed of the above raw materials as appropriate.

[0111] As the polyurethane catalyst mentioned above, it is preferable to use a tertiary amine compound because it reacts with an aqueous blowing agent to generate urea bonds and carbon dioxide. Furthermore, it is preferable to use mainly silicone oil as the foaming agent. Using such a foaming agent is effective in improving the mixability of the raw materials, dispersing bubbles, refining bubbles, and suppressing bubble aggregation.

[0112] The foamed resin composite metal panel 1 according to this embodiment has been described in detail above with reference to Figure 4.

[0113] (Regarding the manufacturing method of foamed resin composite metal panels) Next, the manufacturing method of the foamed resin composite metal panel 1 according to this embodiment, as described above, will be explained.

[0114] In the manufacturing method of the foamed resin composite metal panel 1 according to this embodiment, first, two resin-coated metal plates 10, as previously described, are placed in the upper and lower molds of a RIM (Reaction Injection Molding) apparatus, respectively, so that the resin coating layer 13A is in contact with the foamed resin raw material. Subsequently, the foamed resin raw material is injected into the RIM apparatus, and the curing reaction of the foamed resin and foaming / bubble growth proceed simultaneously, forming a hard foamed resin layer 20. After curing, the molded product is removed from the mold of the RIM apparatus and allowed to cool naturally to obtain the foamed resin composite metal panel 1 according to this embodiment. Herein, the settings of the RIM apparatus are not particularly limited and may be set appropriately according to the characteristics of the foamed resin raw material used.

[0115] Here, if the time between mixing the raw material liquid for the foamed resin layer and injecting it into the apparatus is long, the viscosity of the raw material liquid will increase rapidly as hardening and foaming begin, and the size of the bubbles may increase in areas where the fluidity of the raw material liquid decreases within the apparatus. For this reason, it is preferable to inject the raw material liquid between the two resin-coated metal plates 10 as quickly as possible after mixing the raw material liquid.

[0116] As mentioned earlier, the average particle size of the bubbles 203 in the formation of the foamed resin layer 20 is mainly controlled by the composition of the foamed resin raw materials.

[0117] Conventionally, when the thickness of the foamed resin layer in foamed resin composite metal panels was thin, approximately 10.0 mm or less, the reaction heat generated when the foamed resin raw material was mixed and injected between two resin-coated metal plates softened the coating on the surface of the resin-coated metal plates, hindering the fluidity of the foamed resin raw material. As a result, the foamed resin accumulated locally within the panel, and the generated bubbles tended to aggregate and become coarse. In foamed resin composite metal panels, unevenness in bubble size and bubble density reduces the rigidity of the panel, making it prone to buckling. Therefore, conventionally, there were limitations to reducing the weight of the panel by lowering the density of the foamed resin.

[0118] However, in the foamed resin composite metal panel 1 according to this embodiment, by providing the resin coating layer 13A described above on the surface of the two resin-coated metal plates that are in contact with the foamed resin, it is possible to prevent the coating from softening due to the reaction heat generated while maintaining the fluidity of the foamed resin raw material in a desirable state. As a result, it is possible to reduce the density of the foamed resin and lighten the panel while maintaining the rigidity of the foamed resin composite metal panel 1.

[0119] The manufacturing method of the foamed resin composite metal panel 1 according to this embodiment has been briefly described above. [Examples]

[0120] In the following, the resin-coated metal plate and foamed resin composite metal panel according to this embodiment will be described in detail with reference to examples and comparative examples. Note that the following examples are merely examples of the resin-coated metal plate and foamed resin composite metal panel according to this embodiment, and the resin-coated metal plate and foamed resin composite metal panel according to this embodiment are not limited to the examples below.

[0121] <Fabrication of resin-coated metal plates> Commercially available metal plates, as shown in Table 1 below, were prepared and used as the base material for the resin-coated metal plates. First, each metal plate was immersed in acetone and ultrasonically degreased to clean its surface. Next, a chemical conversion coating, as shown in Table 1, was formed on the surface of each metal plate.

[0122] [Table 1]

[0123] <Preparation of resin raw materials for forming a resin coating layer> Using commercially available resin films and resin particles, resin films as shown in Tables 2-1 to 2-3 below were prepared. In Table 2 below, the meanings of *1 to *5 are as follows. Also, in Tables 2-1 to 2-3 below, "Polyethylene (LDPE)" refers to low-density polyethylene, and "Polyethylene (HDPE)" refers to high-density polyethylene. *1: Polyethylene terephthalate resin film *2: Polyethylene terephthalate / isophthalate 11 mol% copolymer resin film *3: Polyethylene terephthalate / polybutylene terephthalate 40% by mass copolymer resin film *4: Glycol-modified polyethylene terephthalate (PETG) film *5: Softening onset temperature measured by a thermomechanical analyzer (TMA) (the melting point measured by DSC was unclear).

[0124] Furthermore, the surface tensions in Tables 2-1 to 2-3 were determined based on the wettability of the wettability test mixture (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in accordance with JIS K 6768:1999 "Plastics - Films and Sheets - Wetting Tension Test Method".

[0125] More specifically, for the matrix resin raw materials, a sample of the matrix resin alone was prepared for measurement, and the measurement was performed in accordance with JIS K 6768:1999 "Plastics - Films and Sheets - Wetting Tension Test Method". When preparing the sample for measurement, if the matrix resin raw material was of the paint type, the resin was applied to a steel plate as a base material to create a painted plate, and its surface tension was measured. If the matrix resin raw material was of the thermoplastic resin type, the resin pellets were formed into a film using a T-die extruder, and its surface tension was measured.

[0126] Furthermore, for the resin raw materials used in the resin phase, the resin raw materials alone were formed into films using a T-die extruder, and the surface tension of these films was measured in accordance with JIS K 6768:1999 "Plastics - Films and Sheets - Wetting Tension Test Method".

[0127] [Table 2-1]

[0128] [Table 2-2]

[0129] [Table 2-3]

[0130] Films as shown in Tables 2-1 to 2-3, which were formed using a T-die extruder, were fused to the metal plates shown in Table 1 using a film laminating apparatus to form a resin coating layer. The film laminating apparatus used was a dedicated resin film laminating apparatus equipped with a metal plate feeding device, a hot press for heating the metal plates, film feeding devices for the front and back surfaces, a heat-resistant rubber laminating roll, and a cooling water tank. Details of the resin coating layers formed on each metal plate are summarized in Tables 4-1 to 4-3 below.

[0131] <Preparation of foamed resin raw materials> Using commercially available general reagents, foam resin raw materials for forming a foamed resin layer were prepared as shown in Table 3 below.

[0132] [Table 3]

[0133] <Fabrication of foamed resin composite metal panels> The resin-coated metal plate prepared as described above was cut to match the mold size (40 cm in length x 80 cm in width) of the RIM manufacturing machine. The cut resin-coated metal plate was then attached by suction to the upper and lower molds of a panel manufacturing mold, which is equipped with an upper mold and a lower mold having steel plate suction holes, with the resin coating layer on the side to be handled as the resin coating layer 13B in contact with the mold surface.

[0134] Subsequently, the upper and lower molds were closed, and the foamed resin raw materials listed in Table 3, which had been mixed in a mixing tank, were injected through the resin injection port provided in the mold. After 1 minute, the upper and lower molds were opened, the foamed resin composite metal panel was removed, and allowed to cool naturally.

[0135] <Mass measurement of foamed resin composite metal panels> The mass of the foamed resin composite metal panel (40 cm long x 80 cm wide) prepared as described above was measured using a platform scale capable of measuring in 0.01 kg increments, and the obtained measurement result was measured in 1 m 2 It was converted to mass per unit area.

[0136] <Distribution state and area ratio of the resin phase in the resin coating layer> For the foamed resin composite metal panel prepared as described above, the distribution state and area ratio of the resin phase in the resin coating layer corresponding to the resin coating layer 13A were measured in accordance with the method previously described.

[0137] <Average bubble size in the foamed resin layer> The average particle size of bubbles in the foamed resin layer of the foamed resin composite metal panel prepared as described above was measured according to the method previously explained.

[0138] <Average bulk density of the foamed resin layer> The average bulk density of the foamed resin layer in the fabricated foamed resin composite metal panel was measured using a bulk density measurement method. Specifically, the average bulk density was measured by following the steps (a) to (g) below. (a) Using a high-speed precision cutting machine, a 10cm x 10cm sample was cut from the fabricated foamed resin composite metal panel, and the length, width, and thickness of the sample were measured using calipers. The volume of the sample was then determined by calculating length x width x thickness. (b) The mass of the sample obtained in (a) was measured using a precision electronic balance. (c) The same resin-coated metal plate used in the foamed resin composite metal panel of interest was cut into 10cm x 10cm pieces, and the length, width, and overall thickness of the cut samples were measured with a micrometer. This allowed the volume of the resin-coated metal plate used in the foamed resin composite metal panel of interest to be determined by calculating length x width x thickness. The mass of the resin-coated metal plates in (d) and (c) was measured using a precision electronic balance. The mass of the foamed resin layer alone was calculated by subtracting twice the mass of the resin-coated metal plate sample (d) from the mass of the foamed resin composite metal panel sample (b). (f) The volume of the foamed resin layer alone was calculated by subtracting twice the volume of the resin-coated metal plate sample (c) from the volume of the foamed resin composite metal panel sample (a). The bulk density of the foamed resin layer was calculated by dividing the mass of the foamed resin layer in (g)(e) by the volume of the foamed resin layer in (f).

[0139] The above series of steps was performed on multiple samples taken from the same foamed resin composite metal panel, and the average bulk density of the foamed resin layer was obtained by averaging the obtained bulk densities.

[0140] <Evaluation of foamed resin composite metal panels> Each foamed resin composite metal panel manufactured as described above was evaluated from the perspectives of peel strength and panel impact resistance.

[0141] [Peel strength] For the fabricated foamed resin composite metal panel, when viewed from above in a plan view, three locations were cut in the thickness direction using a high-speed precision cutting machine at the 1 / 4, 1 / 2, and 3 / 4 positions in the width direction of the vertical center of the panel, thereby obtaining test specimens measuring 25 mm in length and 150 mm in width. For each test specimen, approximately 30 mm of the resin coating layer on both sides located at the widthwise ends was peeled off to create the gripping portion of the tensile testing machine's chuck.

[0142] The chuck gripping portions on both sides of the test specimen were clamped in the chucks of a tensile testing machine, and the specimen was peeled 100 mm at a tensile speed of 20 mm / min (chuck movement of 200 mm). The peel strength between the resin-coated metal plate and the foamed resin layer was then measured.

[0143] The obtained peel strength over the entire length of the peel was evaluated according to the following evaluation criteria, and a score of "A" or "B" was considered a passing grade. ◇Evaluation Criteria Rating "A": Peel strength of 15N / 25mm or higher "B": Peel strength is 10N / 25mm or more and less than 15N / 25mm "C": Peel strength is 5N / 25mm or more and less than 10N / 25mm "D": Peel strength is less than 5N / 25mm

[0144] [Panel Impact Resistance Test] The impact resistance test of the panel was conducted using a foamed resin composite metal panel measuring 40 cm (length) x 80 cm (width). Two wooden stands measuring 50 cm (length) x 20 cm (width) x 5 cm (height) were prepared and placed side by side with a 40 cm gap between them. The foamed resin composite metal panel of the above size was supported by the two wooden stands, with the 0-20 cm and 60-80 cm sections (with a 40 cm distance between support points) of the panel positioned on the wooden stands. A poly tank filled with water and weighing 20 kg was dropped from a height of 30 cm onto the center of the panel positioned as described above.

[0145] The impact resistance of the panels was assessed by visually observing the degree of deformation, and evaluated according to the following evaluation criteria, with scores of "A" and "B" being considered passing grades. ◇Evaluation Criteria Rating "A": No panel buckling or deflection. "B": Buckling occurred in the surface material (coated resin metal plate) of a portion of the panel, but there was no overall bending. "C": The panel's surface material (coating resin metal plate) peeled off, and the panel completely buckled and bent.

[0146] [Table 4-1]

[0147] [Table 4-2]

[0148] [Table 4-3]

[0149] As is clear from Tables 4-1 to 4-3 above, the foamed resin composite metal panel corresponding to the embodiment of the present invention exhibited excellent peel strength and impact resistance, while the foamed resin composite metal panel corresponding to the comparative example of the present invention did not achieve sufficient performance in at least one of peel strength or impact resistance.

[0150] Although preferred embodiments of the present invention have been described in detail above with reference to the attached drawings, the present invention is not limited to these examples. It is clear to any person with ordinary skill in the art to which the present invention belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these are also understood to fall within the technical scope of the present invention.

[0151] The embodiments disclosed herein are illustrative and not restrictive in all respects. The embodiments described above may be omitted, replaced, or modified in various ways without departing from the appended claims, the technical scope of the invention as described later, and the spirit thereof. For example, the constituent elements of the embodiments described above can be combined in any way without impairing their effects. Furthermore, such any combination will naturally yield the effects and benefits of each constituent element in the combination, as well as other effects and benefits that will be obvious to those skilled in the art from the description herein.

[0152] Furthermore, the effects described herein are merely descriptive or illustrative, and not limiting. In other words, the technology according to the present invention may produce other effects that will be apparent to those skilled in the art from the description herein, in addition to or instead of the effects described above.

[0153] Furthermore, the following configurations also fall within the technical scope of the present invention. (1) Two resin-coated metal plates, A foamed resin layer containing air bubbles is provided between the two resin-coated metal plates, It has, Each of the two resin-coated metal plates has a resin coating layer on both sides of the base metal plate. The resin coating layer on the side in contact with the foamed resin layer has a thickness of 8 to 150 μm. In a cross-section of the resin coating layer on the side in contact with the foamed resin layer, a resin phase with a melting point of 100 to 160°C, a surface tension of 30 to 36 mN / m, and an average particle size of 1.0 to 10.0 μm is unevenly distributed within a range of 0 μm to 5 μm in the direction toward the metal plate from the surface in contact with the foamed resin layer, and furthermore, the area ratio of the resin phase in the range of 0 μm to 5 μm in the cross-section is 5 to 50%. The average particle size of the bubbles contained in the foamed resin layer is 30 to 200 μm. The average bulk density of the foamed resin layer is 0.15 to 0.50 g / cm³. 3This is a foamed resin composite metal panel. (2) The foamed resin composite metal panel according to (1), wherein the foamed resin constituting the foamed resin layer is rigid polyurethane foam. (3) The foamed resin composite metal panel according to (1) or (2), wherein the resin coating layer on the side in contact with the foamed resin layer has a matrix resin constituting the resin coating layer having a melting point of 225°C or higher and a surface tension of 42 to 52 mN / m. (4) The foamed resin composite metal panel according to (3), wherein the absolute value of the difference between the surface tension of the matrix resin and the surface tension of the resin constituting the resin phase is 20 mN / m or less. (5) The foamed resin composite metal panel according to (3) or (4), wherein the matrix resin is either a polyester resin or a polyamide resin. (6) The foamed resin composite metal panel according to any one of (1) to (5), wherein the resin phase is composed of at least one of the following resins: polyethylene resin, carboxylic acid-modified polyethylene resin, polypropylene resin, carboxylic acid-modified polypropylene resin, ethylene-propylene copolymer resin, or carboxylic acid-modified ethylene-propylene copolymer resin. (7) The foamed resin composite metal panel according to any one of (1) to (6), wherein the thickness of the foamed resin layer is 3.0 to 48.0 mm. (8) The foamed resin composite metal panel according to any one of (1) to (7), wherein the thickness of the metal plate is 0.1 to 2.0 mm. (9) The foamed resin composite metal panel described in any one of (1) to (8), wherein the overall thickness of the foamed resin composite metal panel is 3.0 to 50.0 mm. (10) A metal plate that serves as the base material, A resin coating layer is provided on both sides of the aforementioned metal plate, It has, The resin coating layer provided on at least one surface of the metal plate is The thickness is 8 to 150 μm, and A resin-coated metal plate, wherein in a cross-section obtained by cutting the resin coating layer in the thickness direction, a resin phase having a melting point of 100 to 160°C, a surface tension of 30 to 36 mN / m, and an average particle size of 1.0 to 10.0 μm is unevenly distributed within a range of 0 μm to 5 μm from the surface of the bark coating layer along the thickness direction, and furthermore, the area ratio of the resin phase in the range of 0 μm to 5 μm in the cross-section is 5 to 50%. (11) The resin-coated metal plate according to (10), wherein the matrix resin constituting the resin coating layer in which the resin phase is unevenly distributed has a melting point of 225°C or higher and a surface tension of 42 to 52 mN / m. (12) The resin-coated metal plate according to (11), wherein the absolute value of the difference between the surface tension of the matrix resin and the surface tension of the resin constituting the resin phase is 20 mN / m or less. (13) The resin-coated metal plate according to (11) or (12), wherein the matrix resin is either a polyester resin or a polyamide resin. (14) The resin-coated metal plate according to any one of (10) to (13), wherein the resin phase is composed of at least one of the following resins: polyethylene resin, carboxylic acid-modified polyethylene resin, polypropylene resin, carboxylic acid-modified polypropylene resin, ethylene-propylene copolymer resin, or carboxylic acid-modified ethylene-propylene copolymer resin. (15) The resin-coated metal plate described in any one of (10) to (14), wherein the thickness of the metal plate is 0.1 to 2.0 mm. [Explanation of Symbols]

[0154] 1. Foamed resin composite metal panel 10 Resin-coated metal plate 11 Metal plate 13A, 13B Resin coating layer 20 Foamed resin layer 101 Matrix resin 103 Resin phase 201 Foamed resin 203 bubbles

Claims

1. Two resin-coated metal plates, A foamed resin layer containing air bubbles is provided between the two resin-coated metal plates, It has, Each of the two resin-coated metal plates has a resin coating layer on both sides of the base metal plate. The resin coating layer on the side in contact with the foamed resin layer has a thickness of 8 to 150 μm. In a cross-section obtained by cutting the resin coating layer on the side in contact with the foamed resin layer in the thickness direction, a resin phase having a melting point of 100 to 160°C, a surface tension of 30 to 36 mN / m, and an average particle size of 1.0 to 10.0 μm is unevenly distributed within a range of 0 μm to 5 μm in the direction toward the metal plate from the surface in contact with the foamed resin layer, and furthermore, the area ratio of the resin phase in the range of 0 μm to 5 μm in the cross-section is 5 to 50%. The average particle size of the bubbles contained in the foamed resin layer is 30 to 200 μm. The average bulk density of the foamed resin layer is 0.15 to 0.50 g / cm³. ３ This is a foamed resin composite metal panel.

2. The foamed resin composite metal panel according to claim 1, wherein the foamed resin constituting the foamed resin layer is a rigid polyurethane foam.

3. The foamed resin composite metal panel according to claim 1 or 2, wherein the resin coating layer on the side in contact with the foamed resin layer has a matrix resin constituting the resin coating layer having a melting point of 225°C or higher and a surface tension of 42 to 52 mN / m.

4. The foamed resin composite metal panel according to claim 3, wherein the absolute value of the difference between the surface tension of the matrix resin and the surface tension of the resin constituting the resin phase is 20 mN / m or less.

5. The foamed resin composite metal panel according to claim 3, wherein the matrix resin is either a polyester resin or a polyamide resin.

6. The foamed resin composite metal panel according to claim 1 or 2, wherein the resin phase is composed of at least one of the following resins: polyethylene resin, carboxylic acid-modified polyethylene resin, polypropylene resin, carboxylic acid-modified polypropylene resin, ethylene-propylene copolymer resin, or carboxylic acid-modified ethylene-propylene copolymer resin.

7. The foamed resin composite metal panel according to claim 1 or 2, wherein the thickness of the foamed resin layer is 3.0 to 48.0 mm.

8. The foamed resin composite metal panel according to claim 1 or 2, wherein the thickness of the metal plate is 0.1 to 2.0 mm.

9. The foamed resin composite metal panel according to claim 1 or 2, wherein the overall thickness of the foamed resin composite metal panel is 3.0 to 50.0 mm.

10. A metal plate that serves as the base material, A resin coating layer is provided on both sides of the aforementioned metal plate, It has, The resin coating layer provided on at least one surface of the metal plate is The thickness is 8 to 150 μm, and A resin-coated metal plate, wherein in a cross-section obtained by cutting the resin coating layer in the thickness direction, a resin phase having a melting point of 100 to 160°C, a surface tension of 30 to 36 mN / m, and an average particle size of 1.0 to 10.0 μm is unevenly distributed within a range of 0 μm to 5 μm from the surface of the bark coating layer along the thickness direction, and furthermore, the area ratio of the resin phase in the range of 0 μm to 5 μm in the cross-section is 5 to 50%.

11. The resin-coated metal plate according to claim 10, wherein the matrix resin constituting the resin coating layer in which the resin phase is unevenly distributed has a melting point of 225°C or higher and a surface tension of 42 to 52 mN / m.

12. The resin-coated metal plate according to claim 11, wherein the absolute value of the difference between the surface tension of the matrix resin and the surface tension of the resin constituting the resin phase is 20 mN / m or less.

13. The resin-coated metal plate according to claim 11, wherein the matrix resin is either a polyester resin or a polyamide resin.

14. The resin-coated metal plate according to claim 10 or 11, wherein the resin phase is composed of at least one of the following resins: polyethylene resin, carboxylic acid-modified polyethylene resin, polypropylene resin, carboxylic acid-modified polypropylene resin, ethylene-propylene copolymer resin, or carboxylic acid-modified ethylene-propylene copolymer resin.

15. The resin-coated metal plate according to claim 10 or 11, wherein the thickness of the metal plate is 0.1 to 2.0 mm.

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