Surface observation method for resin molded body

Abstract

To easily observe a surface condition of a resin molding.SOLUTION: In a method for observing a surface of a resin molding, a halogenated solution containing a halogen element is coated on the surface of the resin molding, so that a halide ion contained in the applied halogenated solution impregnates according to a surface condition of the resin molding, in order to evaluate a surface condition of the resin molding on the basis of observation results of a coloring density distribution due to colored trihalide ions, pentahalide ions and / or the halogen element, and a luminescence distribution in an X-ray image according to the halogen element which can serve as a contrast medium.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a surface observation method for a resin molded body, and more particularly to a surface observation method for a resin molded body for analyzing the surface condition of the resin molded body and the cause of fracture on the fracture surface. [Background technology]

[0002] Traditionally, when a plastic part made from a resin molded body breaks, fractography is performed to investigate the cause. Fractography is a method widely used, mainly in the metals field, to estimate the fracture mechanism or cause of fracture from the characteristics of the fracture surface pattern, but since resin materials also show a variety of fracture surface patterns depending on the fracture mechanism, just like metal materials, similar analytical techniques have been adopted, and the origin of fracture on the fracture surface of a resin molded body is generally confirmed using a stereomicroscope or a scanning electron microscope (SEM).

[0003] Meanwhile, a method for observing the fracture surface of a resin molded body has been disclosed in which a contrast agent containing iodine or the like is used with X-ray CT to observe the penetration behavior of the contrast agent, making it possible to visualize information on density, crystallinity, orientation, and the like (see Patent Document 1). Also, a penetrant inspection method is available as a method for detecting the position and size of surface defects. This method uses capillary action to detect defects such as cracks by penetrating a liquid, and it has been disclosed that it can also be applied to resins (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-233751 [Patent Document 2] Special Publication No. 49-107587 Summary of the Invention [Problem to be solved by the invention]

[0005] When identifying the origin of fracture on the fracture surface of a resin molded product using a stereo microscope or SEM, the area that can be observed at one time is small, so samples with large fracture surfaces require multiple repeated observations. In particular, molded products containing inorganic fillers such as glass fiber reinforcement exhibit irregular fracture patterns due to the influence of glass fiber orientation, making it difficult to identify the origin of fracture and requiring significant time for observation. Furthermore, while penetrant testing can easily identify open defects on the surface of molded products, such as cracks in resin parts, identifying the origin of fracture deep within the cracks requires further cutting of the sample and observation with an SEM or stereo microscope. Furthermore, observation with X-ray CT using contrast agents containing iodine requires preparations such as cutting the sample and image processing, making it difficult to conduct simple investigations.

[0006] This invention has been proposed in consideration of the above-mentioned situation, and aims to provide a method for observing the surface of a resin molded body that can be easily performed without requiring much effort in observation and preparation when observing the surface condition of a resin molded body. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the surface observation method of the resin molded body according to this application includes a step of applying a halogenated solution containing a halogen element to the surface of the resin molded body, and a step of determining the surface condition of the resin molded body based on the results of observation in the visible light and radiation regions regarding the distribution of the halogen element contained in the applied halogenated solution on the surface of the resin molded body.

[0008] The process of determining the surface condition of the resin molded body may involve determining, for an observation area on the surface of the resin molded body, an observation area in which the distribution of halogen elements is relatively dense, such that the distribution is relatively dark in the visible light region and the absorption is relatively large in the radiation region, as a ductile fracture area, and determining, for an observation area in which the distribution of halogen elements is relatively sparse, such that the distribution is relatively light in the visible light region and the absorption is relatively small in the radiation region, as a brittle fracture area.

[0009] The step of determining the surface condition of the resin molding may include determining, for the ductile fracture region and the brittle fracture region adjacent to each other on the fracture surface of the resin molding, that the ductile fracture region is the origin of the fracture surface.

[0010] The halide solution may be an alkali metal halide salt solution. The alkali metal may be a halide salt where sodium or potassium is used. The halide solution may include iodine and potassium iodide. [Effects of the Invention]

[0011] According to the present invention, the surface condition of a resin molding, particularly the ductile fracture region, can be easily observed. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view illustrating a first mode in which a test piece is broken following three-point bending. [Figure 2] 1 is a photograph illustrating the staining caused by dilute iodine tincture applied to the fracture surface of a test specimen. [Figure 3] FIG. 10 is a perspective view illustrating a second mode in which a test piece breaks following three-point bending. [Figure 4] FIG. 1 is a diagram illustrating the relationship between a photograph of the fracture surface of a test piece coated with dilute iodine tincture and micrographs of ductile fracture and brittle fracture. [Figure 5] FIG. 1 shows a photograph and a CT image of the fracture surface of a test piece to which dilute iodine tincture was applied. [Figure 6] This is a photograph of a potassium iodide solution. [Figure 7] 1 is a photograph of the fracture surface of a test piece coated with potassium iodide. [Figure 8] 1 is a photograph of the fracture surface of a test piece coated with iodotoluene. [Figure 9] FIG. 1 shows a CT image of a test piece coated with iodotoluene. DETAILED DESCRIPTION OF THE INVENTION

[0013] The surface observation method for a resin molded body according to the present application will be described in detail below with reference to the drawings. The surface observation method for a resin molded body according to this embodiment is intended to observe the surface of a resin molded body formed from a resin such as polyacetal (POM), but the resin molded body may be formed from other types of resin. In addition to scratches and sliding marks on the surface of the resin molded body being observed, it is possible to identify ductile fracture regions such as jetting and flow marks that occurred during molding, cracks and crazing that occurred due to residual stress, and, in the case of a fracture surface, ductile fracture regions near the fracture initiation point.

[0014] In this embodiment, the halogen element is preferably bromine (Br2) or iodine (I2), and iodine (I2) is particularly preferred because it is easy to handle. The halogenated solution contains bromine (Br2) or iodine (I2), and dissociates in the solution to form Br - , I - The halide solution may be any solution that produces a color with the halogen ions and can be used as a contrast agent for radiographic imaging, and may be an alkali metal halide salt solution. The alkali metal in the alkali metal salt solution may be sodium or potassium.

[0015] Dilute iodine tincture, which is used for medical purposes, is an example of a halogenated solution containing easily available halogen elements. Dilute iodine tincture is a solution containing iodine (I2) and potassium iodide (KI) as halogen elements, and is prepared by dissolving iodine and potassium iodide in an ethanol solution. Dilute iodine tincture is prepared by dissolving iodine in an ethanol solution through the intervention of potassium iodide, and the iodine is dissolved in an ethanol solution to form I3 - or I5 - The brown color is produced by the generation of iodine-based pigments such as: Furthermore, iodine has a large atomic weight, making it suitable as a contrast agent for X-ray imaging.

[0016] Furthermore, in this embodiment, observation in the radiation region is assumed to be observation using X-rays. Observation using X-rays is not limited to X-ray images obtained by simple imaging using X-rays, and X-ray CT images using computed tomography (CT) technology may also be used. Note that the radiation used for observation is not limited to electromagnetic waves such as X-rays, but may also be charged particles such as electron beams or ion beams.

[0017] In the surface observation method of this embodiment, in the first step, a halogenated solution containing a halogen element is applied to the surface of a resin molded product to be observed. For example, a cotton swab is impregnated with the halogenated solution containing a halogen element and applied to the entire surface of the resin molded product or to a specific region to be observed. The application of the halogenated solution containing a halogen element to the resin molded product is not limited to application using a cotton swab or the like, but may also be by spraying the halogenated solution containing a halogen element, or by immersing the resin molded product in the halogenated solution containing a halogen element. In this specification, the application of the halogenated solution containing a halogen element includes modes such as spraying or impregnation of the halogenated solution containing a halogen element onto the resin molded product.

[0018] The halogenated solution containing halogen elements applied to a resin molded product is distributed according to the surface condition of the applied surface. When the applied surface is a fractured surface, a brittle fracture region is observed adjacent to a ductile fracture region. It is known that the formation of a fracture surface due to fracture occurs when a ductile fracture that occurs from the origin of the fracture surface converts to a brittle fracture as the fracture progresses, and a brittle fracture region is formed adjacent to the ductile fracture region.

[0019] The surface area per unit area of ​​the fracture surface varies depending on the surface condition, and it is known that in the ductile fracture region, the resin is stretched, causing minute elongations, minute cracks, and crazes on the fracture surface, resulting in a relatively large surface area, while in the brittle fracture region, no minute elongations are observed and the surface area is relatively small. For this reason, in the ductile fracture region, the amount of halide ions penetrating into the minute cracks and crazes is large, and after the solution dries, the amount of halogen elements distributed is relatively large. In the brittle fracture region, no minute elongations are observed, and few halide ions penetrate the surface, resulting in a relatively small amount of halogen elements distributed after the solution dries.

[0020] In the surface observation method of this embodiment, in the next step, the distribution of halogen elements on the coated surface of the resin molded article is observed in the visible light region and the radiation region. Here, the visible light region refers to electromagnetic waves with wavelengths of about 360 to 700 nm that can be observed visually by humans. The radiation region is intended for observation using X-rays, as described above.

[0021] In the visible light region, the halogen elements contained in the halogenated solution become trihalide ions or pentahalide ions, which penetrate the coated surface. The halide ions that penetrate the coated surface are colored, so the surface becomes deeply colored. When the surface dries, the trihalide ions and pentahalide ions return to the halogen elements and halogen compounds. However, because the halogen elements are also colored, the density of the halogen distribution on the coated surface can be observed by visually observing the distribution of light and dark colors. Therefore, this method can be used to observe surfaces regardless of whether the halogenated solution has dried or not.

[0022] For example, if the color of a certain observation area on the coated surface is relatively dark compared to other areas, it can be determined that the distribution of the halogen element in this observation area is relatively dense. Conversely, if the color of a certain observation area is relatively light compared to other areas, it can be determined that the distribution of the halogen element in this observation area is relatively sparse. In observing the fracture surface, if there are multiple dark-colored areas on the coated surface, or if they have a pattern such as dots, a mesh, a patch, or a gradation, the darkest colored area may be determined to be the ductile fracture area, which is the initiation point of the initial fracture. If the resin molded product does not contain an inorganic filler, etc., a brittle fracture area may not be confirmed on the fracture surface of creep fracture, fatigue fracture, etc. In such cases, a particularly darkly colored area within the ductile fracture area can be determined to be the initiation point of the fracture.

[0023] As mentioned above, trihalide ions and pentahalide ions penetrate the ductile fracture region of the fracture surface and return to elemental halogens when dried, but in either case, the distribution of halogen elements is relatively high. In the brittle fracture region, penetration of halide ions is low, so the distribution of halogen elements is relatively low, and the distribution of halogen elements is also low. Among the halogen elements contained in the halogenated solution containing halogen elements, the unionized halogen elements do not penetrate into the interior of the resin molded product. Therefore, the color intensity in the applied region is affected by the amount of penetration of halide ions.

[0024] In the radiological field, halogen elements can be used as contrast agents because their atomic weight is larger than that of other elements constituting resin moldings, and the distribution of halogen elements can be observed by the brightness distribution in X-ray images of the coated surface. For example, if the brightness of a certain observation area on the coated surface is relatively high compared to other areas, it can be determined that the distribution of halogen elements in this observation area is relatively dense. Conversely, if the brightness of a certain observation area is relatively low compared to other areas, it can be determined that the distribution of halogen elements in this observation area is relatively sparse. Furthermore, by using not only X-ray images obtained by simple imaging but also X-ray CT images, it is possible to determine the distribution of halogen elements in the depth direction of the fracture surface and inside the resin molding.

[0025] When observing an X-ray image, if the absorption in the pixels of a certain observation area on the coated surface is relatively large compared to the pixels of other areas, for example, if the brightness of the pixel is relatively high, the distribution of the halogen element in this observation area is relatively dense, and it can be determined to be a ductile fracture area. Also, if the coated surface is a fracture surface and the absorption in the pixels of the observation area is relatively small compared to other areas, for example, if the brightness of the pixel is relatively low, the distribution of the halogen element in this observation area is relatively sparse, and it can be determined to be a brittle fracture area.

[0026] When the observation area is a fracture surface, whether it is observed in the visible light region or the radiation region, if it is observed that a brittle fracture region is adjacent to a ductile fracture region, the ductile fracture region can be determined to be the fracture initiation point. Such determination of the fracture initiation point can be performed separately in the visible light region and the radiation region. Therefore, by comparing the results of determinations in the visible light region and the radiation region, the accuracy of the determination of the initiation point can be improved.

[0027] According to the surface observation method of this embodiment, when observing a coated surface in the visible light region, the distribution of the shades of colored trihalide ions, pentahalide ions, or halogen elements distributed on the coated surface can be observed by visual inspection, and since no equipment or measurement preparation is required, the time required for observation can be shortened. Furthermore, while scanning electron microscopes (SEMs) and X-ray imaging devices have limitations on the size of samples that can be placed in a tank, it is sufficient to visually observe the fracture surface coated with a halogenated solution containing halogen elements, and there is no size limitation.

[0028] When organic colorants such as dyes or pigments, such as ink, are applied to a resin molding instead of a halogenated solution containing halogen elements, the difference between ductile and brittle fracture regions can sometimes be observed in the visible light range due to differences in the amount of dye soaked in with dyes and the amount of colorant used depending on the layering state of the resin molding surface with pigments. However, because organic colorants do not act as contrast agents, it is not possible to determine the depth direction of the fracture surface or the ductile fracture region inside the resin molding, which cannot be confirmed visually, using X-ray images. Therefore, halogenated solutions containing halogen elements are superior for determining ductile fracture regions even inside resin moldings.

[0029] Although halation may occur when observing a metal composite sample with an X-ray imaging device, visual observation in the visible light range can also be applied to metal composite samples. Furthermore, in the case of complex fracture surfaces, it may be difficult to distinguish between ductile and brittle fracture when a halogenated solution containing halogen elements is applied to the fracture surface and observed with X-rays. However, by visually observing the distribution of the color shades of the trihalide ions, pentahalide ions, or halogen elements applied to the fracture surface, ductile and brittle fractures can be easily distinguished.

[0030] Furthermore, when observing a fracture surface with X-rays, the surface observation method of this embodiment makes it possible to observe the surface condition of a sample that is difficult to distinguish visually, such as a black sample.Furthermore, it is possible to observe the fracture surface in the depth direction and the fracture surface inside the sample, which are difficult to observe visually. [Example]

[0031] An example in which the surface observation method of this embodiment is applied will be described. In the example, as an evaluation material, Duracon (registered trademark) manufactured by Polyplastics is used as a polyacetal (POM) that does not contain a filler. POM M90-44 (hereinafter sometimes referred to as M90-44 (unfilled)) and Duracon (registered trademark) manufactured by Polyplastics, a polyacetal containing glass fiber reinforcement. POMGH-25 (hereinafter sometimes referred to as GH-25 (GF reinforced material)) was prepared. Then, test pieces with dimensions of 80 mm x 10 mm x 4 mm were prepared using M90-44 (unfilled material) and GH-25 (GF reinforced material). Here, POM To make it easier to identify the fracture initiation point, a notch was made in the M90-44 (unfilled material) at approximately the center of the specimen's length along one of the short sides of the rectangular cross section that was approximately perpendicular to the length. The notch was cut to a depth of 2 mm at a 45° angle.

[0032] (Experimental Example 1) FIG. 1 is a perspective view illustrating a first mode of breaking a test specimen in a three-point bending test. As shown in the figure, a roughly rectangular parallelepiped test specimen made of M90-44 (unfilled material) has a notch formed approximately in the center of its length, with the surface including the short side as the bottom surface defined as the bottom, and the surface opposite the bottom as the top surface. The bottom is supported by two supports near both ends in the lengthwise direction, and an indenter is pressed against the top surface at a position opposite the notch in the lengthwise center. In accordance with ISO 178, the indenter is pressed at a normal testing speed of 2 mm / min, continuing until the test specimen breaks from the notch. Upon breakage, a fracture surface is formed in the test specimen, starting from the notch and extending along the cross section, and the test specimen is separated into two pieces. For convenience, individual test pieces may also be referred to as "test pieces" below.

[0033] Dilute iodine tincture was applied to the fracture surface of one of the test pieces obtained by breakage. Dilute iodine tincture contains iodine I2 (3 g), potassium iodide KI (2 g), ethanol (73.4 ml), and purified water (appropriate amount). A cotton swab was soaked in this dilute iodine tincture and applied to the fracture surface of the test piece.

[0034] Figure 2 is a photograph illustrating the staining caused by the application of dilute iodine tincture to the fracture surface of a test specimen. Figure 2(a) is a photograph showing the fracture surface before the application of dilute iodine tincture. On the fracture surface, the side where the notch is formed is the tensile side, and the compression side pressed down by the indenter. The fracture surface is formed from the notch on the tensile side, and a whitened region is observed following the notch on the tensile side. Here, it is thought that ductile fracture occurs at the origin of the fracture surface formation, and as the formation of the fracture surface progresses, the ductile fracture converts to brittle fracture. Therefore, it is thought that the whitened region following the notch contains ductile fracture.

[0035] Figure 2(b) is a photograph showing the fracture surface after application of dilute iodine tincture. The fracture surface is colored brown by colored iodine ions, but the color varies in shade, with the area following the notch being relatively dark, while the rest of the area is relatively light. Therefore, as mentioned above, the areas with relatively dark coloring are judged to be ductile fracture areas where the iodine distribution is relatively dense. Meanwhile, the other areas with relatively light coloring are judged to be brittle fracture areas where the iodine distribution is relatively sparse.

[0036] (Experimental Example 2) FIG. 3 is a perspective view illustrating a second mode of breaking a test specimen in a three-point bending test. As shown in the figure, a test specimen having a substantially rectangular shape made of GH-25 (GF reinforced material) has a rectangular cross section approximately perpendicular to the longitudinal direction at approximately the center of the longitudinal direction. The surface including one long side of the rectangular cross section is designated as the first side, and the surface opposite the first side is designated as the second side. The first side is supported near both ends in the longitudinal direction by two supports, and an indenter is pressed at approximately the center of the longitudinal direction of the second side. In accordance with ISO 178, the indenter is advanced at a normal testing speed of 2 mm / min until the test specimen breaks. Upon breakage, a fracture surface extending along the cross section is formed on the test specimen, and the test specimen is separated into two pieces. Dilute iodine tincture was applied to the fracture surface of one of the broken pieces. The same dilute iodine tincture as in Experimental Example 1 was used.

[0037] Figure 4 illustrates the relationship between a photograph of the fracture surface of a test piece coated with dilute iodine tincture and micrographs of ductile fracture and brittle fracture. Figure 4(a) is a photograph showing a fracture surface coated with dilute iodine tincture. In the fracture surface colored brown by colored iodine ions, it is observed that the area including the vertex formed by the intersection of one end of the edge formed by the first side surface and the edge forming the short side of the approximately rectangular fracture surface is colored relatively darker than other areas.

[0038] Figure 4(b) is an SEM micrograph of an area where relatively dark coloring is observed. In this area, minute stretching of the resin is observed, and therefore it is determined to be a ductile fracture area. Glass fibers added to the resin are also observed in the micrograph. Figure 4(c) is an SEM micrograph of an area where relatively light coloring is observed, unlike the area where relatively dark coloring is observed. In this area, no minute stretching can be confirmed on the fracture surface, and therefore it is determined to be a brittle fracture area. Glass fibers added to the resin are also observed in the micrograph.

[0039] From the micrographs in Figure 4(b) and Figure 4(c), it was confirmed that the darker areas were ductile fracture areas, and the lighter areas were brittle fracture areas. Therefore, it was confirmed that ductile fracture occurred on the first side of the fracture surface, which was supported by the support, on the tension side, and then the ductile fracture transformed into brittle fracture, and the formation of the fracture surface due to brittle fracture progressed to the second side of the compression side.

[0040] (Experimental Example 3) As in Experimental Example 1, a test piece made of M90-44 (unfilled material) was broken in accordance with the three-point test in the first mode shown in Figure 1. The indenter was pressed down at the normal test speed of 2 mm / min in accordance with ISO 178, and dilute iodine tincture was applied to the fracture surface of one of the test pieces obtained by breaking. The same dilute iodine tincture as in Experimental Example 1 was used.

[0041] Figure 5 shows a photograph and a CT image of the fracture surface of one of the test pieces broken in Experiment 3, on which dilute iodine tincture was applied. Figure 5(a) is a photograph showing the fracture surface to which dilute iodine tincture was applied. As mentioned above, on the fracture surface, the relatively darkly colored area following the notch on the tensile side is determined to be a ductile fracture area. In addition, the relatively lightly colored area is determined to be a brittle fracture area.

[0042] Figure 5(b) shows cross-sectional images taken from three directions by X-ray CT, and Figure 5(c) shows a volume-rendered image constructed from the X-ray CT images. In the cross-sectional image in Figure 5(b) and the volume-rendered image in Figure 5(c), high-brightness areas are observed only on the outermost surface of the fracture surface. The high-brightness areas in the X-ray CT images in Figures 5(a) and 5(b) roughly correspond to the areas that are darkly stained by dilute iodine tincture when observed with visible light, as in Figure 5(a). Therefore, the high-brightness areas are thought to be areas where iodine, which has high absorption, is densely distributed and are ductile fracture areas.

[0043] (Comparative Example 1) Figure 6 is a photograph of potassium iodide solutions. The left side of the figure shows potassium iodide solution in water as a solvent, and the right side of the figure shows potassium iodide solution in ethanol as a solvent. Both are colorless and transparent solutions.

[0044] Figure 7 shows photographs of the fracture surfaces of test specimens coated with potassium iodide solution. Figure 7(a) shows the fracture surface of M90-44 (unfilled material) coated with potassium iodide solution, and Figure 7(b) shows the fracture surface of GH-25 (GF reinforced material) coated with potassium iodide solution. Test specimens with fracture surfaces of M90-44 (unfilled material) and GH-25 (GF reinforced material) were prepared in the same manner as in Experimental Examples 1 and 2, respectively. The potassium iodide solution used was ethanol-based. As shown in Figure 6, potassium iodide solution is colorless. No coloring was observed on the fracture surfaces in either Figure 7(a) or Figure 7(b). Therefore, it was not possible to visually observe the distribution of color intensity on the fracture surface in the visible light range.

[0045] (Comparative Example 2) Figure 8 is a photograph of the fracture surface of a test piece coated with iodotoluene. Figure 8(a) shows the fracture surface of a test piece coated with iodotoluene. This test piece was formed from M90-44 (unfilled material) as in Experimental Example 3 and was broken by pressing at the normal test speed of 2 mm / min. Iodotoluene is colorless, and no coloration was observed on the fracture surface coated with iodotoluene. Therefore, it was not possible to visually observe the distribution of color intensity on the fracture surface in the visible light range.

[0046] For comparison, Figure 8(b) shows the fracture surface of a specimen coated with dilute iodine tincture. The specimen in Figure 8(b) was prepared in the same manner as in Figure 8(a), and the dilute iodine tincture used was the same as in Experimental Example 1. The fracture surface coated with dilute iodine tincture exhibits a brownish-red color, and the distribution of the color shade can be visually observed using visible light. In the figure, a darkly colored ductile fracture region can be observed following the notch on the tensile side.

[0047] Figure 9 shows CT images of the test piece coated with iodotoluene. Figure 9(a) shows the same photograph of the test piece coated with iodotoluene as Figure 8(a). Here, the photograph in Figure 8(a) has been rotated so that the longitudinal direction of the fracture surface extends horizontally in the plane of the page, allowing for comparison with the CT image in Figure 9.

[0048] Figure 9(b) shows X-ray CT images taken from three directions. If Figure 9(a) is a top view of the fracture surface, then the CT images corresponding to the top view are shown in the upper left, the front view in the lower left, and the right side view in the lower right of Figure 9(b). Figure 9(c) is a volume rendering image constructed from the CT images. In the X-ray CT images of Figures 9(b) and 9(c), high brightness can be seen in the areas where fine cracks and crazes were observed on the fracture surface in the photograph of Figure 9(a). [Industrial Applicability]

[0049] The present invention can be used to observe the surface condition of a resin part made of a resin molded body.

Claims

1. A method for observing the surface of a resin molded body, comprising: a step of applying a halogenated solution containing a halogen element to a surface of a resin molded body; and determining the surface condition of the resin molded body based on the results of observation of the distribution of halogen elements contained in the applied halogenated solution on the surface of the resin molded body in the visible light and radiation regions, The step of determining the surface state of the resin molded body includes determining, with respect to an observation region on the surface of the resin molded body, an observation region in which the halogen element distribution is relatively dense, so that the halogen element is relatively dark in the visible light region and has relatively large absorption in the radiation region, as a ductile fracture region, and determining, with respect to an observation region in which the halogen element distribution is relatively sparse, so that the halogen element is relatively light in the visible light region and has relatively small absorption in the radiation region, as a brittle fracture region; The halogenated solution contains iodine and is colored in the visible light region. method.

2. The method according to claim 1, wherein the step of determining the surface condition of the resin molding comprises determining that the ductile fracture region and the brittle fracture region adjacent to each other on the fracture surface of the resin molding are the origin of the fracture surface.

3. 3. The method according to claim 1, wherein the halogenation solution is an alkali metal halide salt solution.

4. 4. The method of claim 3, wherein the alkali metal is a halide salt of sodium or potassium.

5. 5. The method of claim 4, wherein the halogenating solution comprises iodine and potassium iodide.

6. The method of claim 5, wherein the halogenated solution comprises iodine and potassium iodide dissolved in an aqueous ethanol solution.

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