Fluororesin coating structure

Abstract

To provide a fluororesin coating structure that is used in severe conditions such as high temperature and high humidity, and prevents the peeling of fluororesin even when strong impact force is applied thereto.SOLUTION: A fluororesin coating structure has a container-like substrate having a bottom, a side wall extending from the bottom, and a flange part extending in the outer circumferential direction from the top end of the side wall, a first coating layer that covers the bottom and the inner surface of the side wall, and a second coating layer that covers the first coating layer and contains fluororesin. The first coating layer is exposed from the entire periphery of the coverage area of the second coating layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fluororesin coated structure. [Background technology]

[0002] Fluororesin coatings are widely used in cooking utensils and the like, taking advantage of the releasability, slipperiness, stability, and other properties derived from fluororesins. Rice cookers are known as structures coated with fluororesin (referred to as "fluororesin-coated structures" in this specification). In rice cookers, a fluororesin coating is applied to the inner surface of a container-shaped substrate to prevent cooked rice from sticking to the substrate (see Patent Documents 1 and 2).

[0003] The fluororesin coating may contain fluororesin to such an extent that at least the surface portion thereof can exhibit the desired effect of preventing cooked rice from adhering, etc. Patent Document 1 describes that another coating layer (e.g., a primer layer) is provided between the top layer containing fluororesin and the substrate to improve adhesion strength.

[0004] In the case of commercial rice cookers, if a fluororesin coating is applied to the upper surface of the flange of the container-shaped base material, the oven will be used several to several dozen times a day under harsh cooking conditions of high temperature (and sometimes high pressure) and a lot of steam, and furthermore, when the flange comes into contact with the lid when the lid is attached or detached before or after cooking, the fluororesin may peel off and become mixed into the cooked rice as a foreign matter. Patent Document 2 describes that, in order to address such a problem, the fluororesin coating is applied to an area excluding the upper edge of a specified width on the inner circumferential surface of the base material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-159836 A [Patent Document 2] JP 2008-119035 A Summary of the Invention [Problem to be solved by the invention]

[0006] The inventors investigated laminating a coating layer containing a fluororesin (second coating layer) on top of another coating layer (first coating layer) as in Patent Document 1 when applying a fluororesin coating to the inner peripheral surface of a substrate except for the upper edge of a specified width as in Patent Document 2.

[0007] Usually, it is conceivable to mask the upper edge of the above-mentioned predetermined width using a masking tool so that the upper end of the coating area of ​​the first coating layer and the upper end of the coating area of ​​the second coating layer coincide with each other, and then form the first coating layer and the second coating layer in sequence. However, in this method, it has been found that in reality, due to, for example, the powder of fluororesin getting around, the second coating layer may partially protrude from the first coating layer and be formed directly on the surface of the substrate. The second coating layer has a smaller adhesion strength to the substrate than the first coating layer. In addition, the lid used for commercial rice cookers is mechanically abutted against the flange part of the substrate with a relatively large impact force without a cushioning material such as a rubber packing. Therefore, in the above case, if the rice cooker is used as a commercial rice cooker under harsh cooking conditions of high temperature (and sometimes high pressure) and a lot of steam, several to several dozen times a day, and furthermore, when the flange comes into contact with the lid when the lid is attached or detached before or after cooking and a large impact force is repeatedly applied, the second coating layer (containing fluororesin) formed directly on the surface of the base material may peel off and become mixed into the cooked rice as a foreign matter.

[0008] An object of the present invention is to provide a fluororesin coated structure in which the fluororesin is unlikely to peel off even when used under harsh conditions such as high temperature and high humidity and when a strong impact force is applied. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a fluororesin coating structure, comprising: a container-shaped substrate having a bottom, a sidewall extending from the bottom, and a flange extending in an outer circumferential direction from an upper end of the sidewall; a first coating layer covering an inner surface of the bottom and the sidewall; a second coating layer covering the first coating layer and containing a fluororesin; and wherein the first coating layer is exposed from the entire periphery of a coverage area of ​​the second coating layer.

[0010] In one embodiment of the present invention, an upper end of the second coating layer may be located below an upper surface of the flange portion.

[0011] In one embodiment of the present invention, the first coating layer may further cover at least a region of the upper surface of the flange portion adjacent to the inner surface of the side wall portion.

[0012] In one embodiment of the present invention, the upper surface of the flange portion may have an area that is covered with the first coating layer and an area that is exposed from the first coating layer.

[0013] In one embodiment of the present invention, the first coating layer may include an engineering plastic.

[0014] In one embodiment of the present invention, the engineering plastic may include at least one selected from the group consisting of polyethersulfone (PES), polyetheretherketone (PEEK), polyamideimide, and epoxy resin.

[0015] In one embodiment of the present invention, the first coating layer may further contain a fluororesin.

[0016] In one embodiment of the present invention, the first coating layer may have a laminated structure of two or more layers.

[0017] In one embodiment of the present invention, the fluororesin coated structure may be a commercial cooking utensil. Effect of the Invention

[0018] According to the present invention, a first coating layer is provided between a container-shaped substrate and a second coating layer containing a fluororesin, and the first coating layer is exposed from the entire periphery of the coating area of ​​the second coating layer, thereby reliably preventing the second coating layer containing a fluororesin from coming into direct contact with the substrate, thereby providing a fluororesin coated structure in which the fluororesin is unlikely to peel off even when used under harsh conditions such as high temperature and high humidity and when a strong impact force is applied. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram illustrating a fluororesin-coated structure in one embodiment of the present invention, in which (a) is a schematic cross-sectional view of the fluororesin-coated structure, and (b) is a schematic enlarged cross-sectional view of a region surrounded by a dashed line in (a). [Diagram 2] FIG. 2 is a diagram for explaining a fluororesin coating structure in one modified example of the embodiment in FIG. 1, showing a schematic enlarged cross-sectional view of a region corresponding to FIG. 1(b). [Diagram 3] FIG. 2 is a diagram for explaining a fluororesin coating structure in another modified example of the embodiment in FIG. 1, showing a schematic enlarged cross-sectional view of a region corresponding to FIG. 1(b). [Figure 4] FIG. 2 is a diagram for explaining a fluororesin coating structure in yet another modified example of the embodiment in FIG. 1, showing a schematic enlarged cross-sectional view of a region corresponding to FIG. 1(b). [Diagram 5] FIG. 2 is a diagram for explaining a fluororesin coating structure in yet another modified example of the embodiment in FIG. 1, showing a schematic enlarged cross-sectional view of a region corresponding to FIG. 1(b). [Figure 6] FIG. 2 is a diagram for explaining a fluororesin coating structure in a comparative example, showing a schematic enlarged cross-sectional view of a region corresponding to FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, a fluororesin coating structure in one embodiment of the present invention will be described in detail, but the present invention is not limited to this embodiment.

[0021] Referring to FIG. 1, a fluororesin coating structure 20 of the present embodiment has a container-like substrate 9 having a bottom 1, a side wall 3 extending from the bottom 1, and a flange 5 extending radially outward from the upper end of the side wall 3.

[0022] The substrate 1 has a container-like structure as a whole. The inner surface 2 of the bottom 1 and the inner surface 4 of the side wall 3 constitute the inner surface of the container. The flange 5 may have a flat upper surface 6, and the upper surface 6 of the flange 5 may contact a lid (not shown) to seal the internal space of the container. When the bottom 1, the side wall 3, and the flange 5 are integrally formed, the boundaries between them are not necessarily clear, but are shown by dotted lines in the accompanying drawings for convenience. The substrate 1 may be made of any appropriate material, and when the fluororesin coating structure 20 is a cooking utensil, it may be made of a thermally conductive material, typically a metal. For example, when the fluororesin coating structure 20 is a rice cooker, the substrate 1 may be made of aluminum.

[0023] The fluororesin coating structure 20 further has a first coating layer 11 that covers the inner surfaces of the bottom portion 1 and the side wall portion 3. More specifically, the first coating layer 11 may continuously cover the entire inner surface 2 of the bottom portion 1 and at least a part of the inner surface 4 of the side wall portion 3. In the embodiment shown in Fig. 1, the upper end 12 of the first coating layer 11 is located below the upper surface 6 of the flange portion 5, more specifically, by a distance B (thus, the entire upper surface 6 of the flange portion 5 and the upper end region of the inner surface 4 of the side wall portion 3 are exposed from the first coating layer 11), but this is not essential to the present invention.

[0024] The first coating layer 11 can appropriately bond the base material 9 and the second coating layer 13, and can be made of any suitable material as long as it is more difficult to peel off from the base material 9 than the second coating layer 13 (has high durability). For example, the first coating layer 11 may be made of any suitable resin or may be mainly composed of any suitable resin.

[0025] More specifically, the first coating layer 11 may contain an engineering plastic. Thereby, the first coating layer 11 can be laminated on the base material 9 with high adhesion strength and can have high hardness.

[0026] The engineering plastic may be at least one selected from the group consisting of those other than fluororesins, such as polyethersulfone (PES), polyetheretherketone (PEEK), polyamideimide (PAI), polyimide (PI), epoxy resin, polyphenylene sulfide (PPS), polysulfone (PSU), polyphenylsulfone (PPSU), polybenzimidazole (PBI), and polyetherimide (PEI).

[0027] In addition to the engineering plastic, the first coating layer 11 may further contain a fluororesin. Thereby, the second coating layer 13 containing the fluororesin can be laminated on the first coating layer 11 with high adhesion strength.

[0028] The fluororesin that can be contained in the first coating layer 11 may be the same as or different from the fluororesin that can be contained in the second coating layer 13 described below. The fluororesin that can be contained in the first coating layer 11 may be, for example, at least one selected from the group consisting of tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-tetrafluoroethylene-hexafluoropropylene copolymer (EFEP), chlorotrifluoroethylene polymer (PCTFE), and tetrafluoroethylene polymer (PTFE).

[0029] The first coating layer 11 may be a single layer or may have a laminated structure of two or more layers. For example, when the first coating layer 11 has a laminated structure of two layers, the first coating layer 11 may be composed of a primer layer formed on the substrate 11 and a middle layer formed by laminating the primer layer on the substrate 11. The primer layer may contain an engineering plastic and may not contain a fluororesin, and the middle layer may contain an engineering plastic and a fluororesin.

[0030] The thickness of the first coating layer 11 is not particularly limited, but may be, for example, 1 μm or more and 1000 μm or less.

[0031] The fluororesin coating structure 20 further includes a second coating layer 13 that covers the first coating layer 11 and contains a fluororesin. In the embodiment shown in Fig. 1, an upper end 14 of the second coating layer 13 is located below the upper surface 6 of the flange portion 5, more specifically, at a position lower by a distance A, but this is not essential to the present invention.

[0032] The second coating layer 13 may contain a fluororesin to an extent that it can exert a desired effect (for example, in the case of a rice cooker, preventing cooked rice from sticking, etc.) For example, the second coating layer 13 may be made of a fluororesin or may have a fluororesin as its main component.

[0033] The fluororesin contained in the second coating layer 13 may be, for example, at least one selected from the group consisting of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-tetrafluoroethylene-hexafluoropropylene copolymer (EFEP), chlorotrifluoroethylene polymer (PCTFE), and tetrafluoroethylene polymer (PTFE).

[0034] The second coating layer 13 can be understood as the outermost layer of the fluororesin coating, that is, the top layer. The second coating layer 13 can be suitably used as a release layer for releasing food in the food industry.

[0035] The thickness of the second coating layer 13 is not particularly limited, but may be, for example, 1 μm or more and 1000 μm or less.

[0036] In this embodiment, the first coating layer 11 is exposed from the entire circumference of the covered area of ​​the second coating layer 13. More specifically, the second coating layer 13 may continuously cover a part of the inner surface of the first coating layer 11, and the first coating layer 11 may be exposed from the entire outer circumference of the covered area of ​​the second coating layer 13. In the embodiment shown in Fig. 1, the upper end 12 of the first coating layer 11 is located at a position higher than the upper end 14 of the second coating layer 13 by a distance C, and therefore, the first coating layer 11 is exposed circumferentially from the upper end 14 of the second coating layer 13 (in other words, the outer circumference of the covered area of ​​the second coating layer 13) with a width corresponding to the distance C.

[0037] Distance C may be, for example, 1 mm or more and 200 mm or less, particularly 50 mm or less. Although not essential to the present invention, distance A may be, for example, 1 mm or more and 200 mm or less, particularly 50 mm or less, and distance B may be, for example, 0 mm or more and 199 mm or less.

[0038] The first coating layer 11 is exposed from the entire periphery of the area covered by the second coating layer 13, thereby reliably preventing the second coating layer 13 from coming into direct contact with the substrate 9. Therefore, according to the fluororesin coating structure 20 of the present embodiment, even if it is used under harsh conditions such as high temperature and high humidity and a strong impact force is applied, peeling of the second coating layer 13 (containing fluororesin) can be effectively prevented, and therefore a fluororesin coating structure 20 with a long coating life (excellent durability) can be realized.

[0039] The fluororesin coating structure 20 of this embodiment may be an article in the food industry where release of food is desired, and may be, for example, a cooking utensil and / or a commercial cooking utensil. In a commercial cooking utensil, a lid (not shown), which may be made of metal, may be mechanically abutted against the upper surface 6 of the flange portion 5 of the base material 9 with a relatively large impact force without a cushioning material such as a rubber packing. The commercial cooking utensil may be, for example, a commercial rice cooker. Even if the fluororesin coating structure 20 is used as a commercial rice cooker under harsh rice cooking conditions of high temperature (potentially high pressure) and high steam content several to several dozen times a day, and further, when the lid is attached or detached before or after cooking rice, and a large impact force is repeatedly applied to the upper surface 6 of the flange portion 5 by contacting the lid, the second coating layer (containing fluororesin) 13 can be effectively prevented from peeling off, and the problem of the fluororesin being mixed into cooked rice as a foreign matter can be eliminated.

[0040] The fluororesin coating structure of the present invention is not limited to the above-described embodiment, and various modifications are possible.

[0041] As one modified example, referring to FIG. 2, in a fluororesin coating structure 21, the first coating layer 11' further covers at least a region 6a adjacent to the inner surface 4 of the side wall 3 on the upper surface 6 of the flange 5. The upper surface 6 of the flange 5 may have a region 6a covered with the first coating layer 11' and a region 6b exposed from the first coating layer 11'. In the embodiment shown in FIG. 2, the first coating layer 11' covers a region (inner peripheral region) 6a adjacent to the inner surface 4 of the side wall 3 on the upper surface 6 of the flange 5, but does not cover a region (outer peripheral region) 6b extending from the region 6a in the outer peripheral direction. The position of the end 12' of the first coating layer 11' is not particularly limited.

[0042] 3, in a fluororesin coating structure 23, the first coating layer 11' further covers at least a region 6a of the upper surface 6 of the flange portion 5 that is adjacent to the inner surface 4 of the side wall portion 3. Furthermore, the second coating layer 13' reaches the upper surface 6 of the flange portion 5 and covers the first coating layer 11'. The position of the end 14' of the second coating layer 13' is not particularly limited.

[0043] As yet another modified example, referring to FIG. 4, a fluororesin coating structure 25 has a protruding portion 7 protruding from the upper surface 6 at the edge of the upper surface 6 of the flange 5, and the first coating layer 11'' extends on the upper surface 6 of the flange 5 such that an end 12'' thereof reaches the inner surface (side wall) of the protruding portion 7. The position of the end 14 of the second coating layer 13 is not particularly limited. The second coating layer 13 may not reach the upper surface 6 of the flange 5 as shown in the figure, or may reach the upper surface 6 of the flange 5 and cover the first coating layer 11''. The protruding portion 7 may be, for example, a fitting portion for fitting the container-shaped substrate 9 with a lid (not shown), but is not limited thereto.

[0044] As yet another modification example, referring to FIG. 5, the fluororesin coating structure 27 has a protruding portion 7 protruding from the upper surface 6 at the edge of the upper surface 6 of the flange 5, and the first coating layer 11''' extends on the upper surface 6 of the flange portion 5 and the inner surface (side wall portion) of the protruding portion 7 such that its end portion 12''' reaches near the upper surface 8 of the protruding portion 7. The position of the end portion 14'' of the second coating layer 13'' is not particularly limited. The second coating layer 13'' may reach the upper surface 6 of the flange portion 5 and cover the first coating layer 11''', or may not reach the upper surface 6 of the flange portion 5. The protruding portion 7 may be, for example, a fitting portion for the container-shaped substrate 9 to fit with a lid (not shown), but is not limited thereto.

[0045] In any of the modification examples of the fluororesin coating structures 21, 23, 25, 27 shown in FIGS. 2 to 5, the first coating layers 11', 11'', 11''' are exposed from the entire circumference of the covering regions of the second coating layers 13, 13', 13'', thereby reliably preventing the second coating layers 13, 13', 13'' from directly contacting the substrate 9. Since the first coating layers 11', 11', 11''' are laminated on the substrate 9 with a higher adhesion strength than the second coating layers 13, 13', 13'', even if a lid (not shown) mechanically contacts the first coating layers 11', 11'', 11''' on the region 6a and, in some cases, the inner surface (side wall portion) of the protruding portion 7 with a relatively large impact force without a buffer material such as a rubber packing, the concern that the first coating layers 11', 11'', 11''' will peel off can be substantially ignored. Therefore, the fluororesin coating structures 21, 23, 25, 27 can exhibit the same effects as the above-described fluororesin coating structure 20.

[0046] In contrast, in the fluororesin coating structure 60 of the comparative example shown in FIG. 6, when the first coating layer 61 and the second coating layer 63 are formed with equal coverage areas covering a position lower than the upper surface 6 of the flange portion 5 by a distance D, the upper end 64 of the second coating layer 63 protrudes upward from the upper end 62 of the first coating layer 61 and is formed directly on the surface of the substrate (the inner surface of the side wall portion 3 in the example shown in FIG. 6). It is difficult to form the second coating layer 63 without the upper end 64 of the second coating layer 63 protruding upward (for example, when the second coating layer 63 is formed by electrostatic coating, fluororesin powder may get around and invade between the masking jig and the coated object). In such a fluororesin coating structure 60, the portion of the second coating layer 63 that is in direct contact with the substrate is easily peeled off. If the fluororesin coated structure 60 is used as a commercial rice cooker under harsh cooking conditions of high temperature (and sometimes high pressure) and a lot of steam, several to several dozen times a day, and further, when the upper surface 6 of the flange portion 5 comes into contact with the lid when the lid is attached or detached before or after cooking and a large impact force is repeatedly applied, the second coating layer (containing the fluororesin) 63 may peel off and become mixed into the cooked rice as a foreign matter.

[0047] In addition, the description of the above embodiment can be applied to the fluororesin coating structures of the modified examples and comparative examples unless otherwise specified. EXAMPLES

[0048] Example 1 Example 1 relates to an example in which a fluororesin coating structure 20 shown in FIG. 1 was produced.

[0049] First, the base material 9 was prepared by subjecting die-cast aluminum to a blasting treatment (although it is not necessary to subject it to an anodizing treatment and a heat treatment).

[0050] Thereafter, a liquid composition containing PEEK in a solvent was sprayed onto the upper surface of the flange portion and the inner surface of the side wall portion in an area corresponding to distance B while the area was masked with a masking jig, the masking jig was removed, and the material was dried (solvent removed) and baked.

[0051] Next, a liquid composition containing PES and PTFE in a solvent was sprayed on the surface while masked with a masking tool in the same manner as above, and the masking tool was removed, followed by drying (solvent removal).

[0052] Next, PFA powder was electrostatically coated on the upper surface of the flange portion and the inner surface of the side wall surface in an area corresponding to the distance A while being masked with a masking jig, the masking jig was removed, and the material was fired.

[0053] In this manner, a fluororesin coating structure sample of Example 1 was obtained. In Example 1, distance B was about 0 mm and distance A was about 10 mm (hence, distance C was about 10 mm). The thickness of the first coating layer was about 15 μm, and the thickness of the second coating layer was about 45 μm.

[0054] When the obtained fluororesin-coated structure sample was visually inspected, it was found that the first coating layer was exposed from the entire periphery of the area covered by the second coating layer, and no part of the second coating layer was found to protrude from the first coating layer. [Industrial Applicability]

[0055] The fluororesin coated structure of the present invention can be used, for example, as a cooking utensil, particularly a cooking utensil for commercial use; however, the uses of the fluororesin coated structure of the present invention are not limited thereto and the structure can be used in a wide variety of applications. [Explanation of symbols]

[0056] 1 bottom 2 Inner surface (bottom) 3 Side wall 4 Inner surface (side wall) 5 Flange 6 Top surface (flange part) 6a, 6b area 7 Protrusion 8 Top surface (protrusion) 9 Container-shaped base material 11, 11', 11'', 11''' 1st coating layer 12 Top end (first coating layer) 12', 12'', 12'' ends (first coating layer) 13, 13', 13'' 2nd coating layer 14 Top end (second coating layer) 14', 14'' ends (second coating layer) 20, 21, 23, 25, 27 Fluorine resin coating structure

Claims

1. A fluororesin coating structure, a container-shaped substrate having a bottom, a sidewall extending from the bottom, and a flange extending in an outer circumferential direction from an upper end of the sidewall; a first coating layer covering an inner surface of the bottom and the sidewall; a second coating layer covering the first coating layer and containing a fluororesin; The first coating layer is exposed from the entire periphery of the covering area of ​​the second coating layer, On the upper surface of the flange portion, there is a region covered with the first coating layer and a region exposed from the first coating layer. Fluororesin coated structure.

2. The fluororesin coating structure according to claim 1 , wherein an upper end of the second coating layer is located below an upper surface of the flange portion.

3. 3. The fluororesin coating structure according to claim 1, wherein the first coating layer further covers at least an area of ​​the upper surface of the flange portion adjacent to the inner surface of the side wall portion.

4. The fluororesin coating structure according to any one of claims 1 to 3, wherein the first coating layer comprises an engineering plastic.

5. 5. The fluororesin coating structure according to claim 4, wherein the engineering plastic comprises at least one selected from the group consisting of polyethersulfone, polyetheretherketone, polyamideimide, and epoxy resin.

6. The fluororesin coating structure according to claim 4 or 5, wherein the first coating layer further comprises a fluororesin.

7. The fluororesin coating structure according to any one of claims 1 to 6, wherein the first coating layer has a laminated structure of two or more layers.

8. The fluororesin coated structure according to any one of claims 1 to 7, which is a commercial cooking utensil.

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