Foreign body detection method for colored recycled resin

Abstract

To provide a foreign body detection method that easily detects foreign bodies contained in colored recycled resin.SOLUTION: Provided is a method for detecting foreign bodies contained in colored recycled resin, comprising: a colored sheet creation step of creating a colored sheet S2 made of colored recycled resin; an inspection sheet creation step of creating an inspection sheet S3 by heat-pressing the created colored sheet S2 and a pair of uncolored sheets S1 made of uncolored resin so as to mix the colored recycled resin with the uncolored resin in a state of sandwiching the colored sheet S2 between the pair of uncolored sheets S1; and a foreign body detection step of detecting foreign bodies contained in the inspection sheet S3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a foreign matter detection method for detecting foreign matter contained in colored recycled resin. [Background technology]

[0002] Conventionally, resins have been reused (recycled) from resin molded products such as thermoplastic resins. Such reused resins are called recycled resins, and are used when producing other products. However, foreign matter may be present in recycled resins due to the surface treatment of molded products before recycling or the manner of use. Since such foreign matter reduces the properties of the product, it is important to know the level of these foreign matter contained. From this point of view, for example, Patent Document 1 discloses a method in which recycled resins are pressed to be flattened into a sheet shape, and foreign matter mixed in the recycled resin is detected. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-070903 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, for example, when the recycled resin is a colored resin (colored recycled resin), even if a foreign matter is mixed in the colored recycled resin, it is difficult to identify the foreign matter. In particular, when the colored recycled resin is colored in a so-called dark color such as black, it is difficult to detect the foreign matter contained therein.

[0005] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a foreign matter detection method that can easily detect foreign matter contained in colored recycled resin. [Means for solving the problem]

[0006] In view of the above problems, the foreign matter detection method for colored recycled resin of the present invention is a method for detecting foreign matter contained in colored recycled resin, and is characterized by including a colored sheet preparation step of preparing a colored sheet made of the colored recycled resin, an inspection sheet preparation step of sandwiching the prepared colored sheet between a pair of uncolored sheets made of uncolored resin, and heat-pressing the colored sheet and the pair of uncolored sheets so that the colored recycled resin and the uncolored resin are mixed, to prepare an inspection sheet, and a foreign matter detection step of detecting the foreign matter contained in the inspection sheet. Effect of the Invention

[0007] According to the present invention, foreign matter contained in colored recycled resin can be easily detected. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2A is a schematic diagram for explaining a colored sheet preparation step in the foreign matter detection method according to the embodiment, and FIG. 2B is a schematic diagram for explaining a test sheet preparation step. [Diagram 2] Photograph (a) shows the results of observing a test sheet, and photograph (b) shows the results of observing a colored sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a method for detecting foreign matter in a colored recycled resin according to an embodiment of the present invention will be described with reference to FIGS.

[0010] [Colored sheet production process] In this process, first, as shown in FIG. 1(a), pellets P2 of colored recycled resin are prepared. The pellets P2 are particles produced by crushing or melting and then granulating resin molded products used in, for example, vehicle dashboards. The colored recycled resin may be a material recycled after consumption, i.e., PCR (Post-Consumer Recycled) material. The colored recycled resin may also be a material recycled from waste materials generated in the manufacturing process, i.e., PIR (Post-Industrial Recycled) material.

[0011] The pellets P2 are resins colored by adding coloring agents or pigments to thermoplastic resins such as polypropylene resin, polyethylene resin, or polypropylene resin. The colored recycled resin is preferably a so-called dark color such as black, dark blue, gray, or dark brown. Since such pellets P2 are produced from the same resin moldings to obtain stable quality, the quality of each pellet P2 is controlled by grade as one rod.

[0012] The pellets P2 made of such colored recycled resin are hot pressed to produce a colored sheet S2. For example, in the case of pellets P2 made of polypropylene resin, the mold temperature during hot pressing is set to 200°C, and about 4 to 10 pellets (about 0.1 g) of pellets P2 are weighed and hot pressed for 1 minute. This allows the production of a colored sheet S2 of about 100 μm.

[0013] Similarly, a pellet P1 of uncolored resin is prepared. The pellet P1 is a particle made of unused resin, and is made of the same type of thermoplastic resin (for example, polypropylene resin) as the pellet P2. Therefore, the pellet P1 has a color inherent to the resin (for example, white or transparent). The pellet P1 is hot-pressed in the same manner as the colored sheet S2 to produce a pair of uncolored sheets S1, S1.

[0014] [Test sheet preparation process] 1(b), in this step, the colored sheet S2 thus produced is sandwiched between a pair of uncolored sheets S1, S1 made of uncolored resin, and the colored sheet S2 and the pair of uncolored sheets S1, S1 are heat-pressed so that the colored recycled resin and the uncolored resin are mixed, to produce an inspection sheet S3. Note that the conditions for heat-press molding of the inspection sheet S3 may be, for example, the same conditions as the heat-press conditions used to produce the colored sheet S2.

[0015] The thickness of each of the uncolored sheets S1 and the colored sheets S2 is not particularly limited, so long as the colored recycled resin and the uncolored resin are uniformly mixed so that the color of the inspection sheet S3 is lighter (diluted) than the color of the colored sheet S2.

[0016] [Foreign matter detection process] In this step, the foreign matter C contained in the inspection sheet S3 is detected. In this embodiment, the color of the inspection sheet S3 is lighter than the color of the colored sheet S2, so the color of the foreign matter contained in the colored sheet S2 is clearly reflected on the surface of the inspection sheet S3. In this way, the foreign matter C contained in the colored recycled resin can be confirmed. In particular, when the color of the colored recycled resin and the color of the foreign matter C are close to each other, the foreign matter C contained in the colored recycled resin becomes easier to detect because the color of the inspection sheet S3 is lighter.

[0017] FIG. 2(a) is a photograph showing the results of observing an inspection sheet, and FIG. 2(b) is a photograph showing the results of observing a colored sheet. As shown in FIG. 2(a), the circular inspection sheet S3 was observed, and a foreign body C was confirmed in the inspection sheet S3. However, as shown in FIG. 2(b), the circular colored sheet S2 was observed, and it was difficult to identify the foreign body C because the color of the colored recycled resin in the colored sheet S2 was close to the color of the foreign body C. In addition, multiple voids B were observed in the colored sheet S2.

[0018] In the foreign matter detection process, both sides of the inspection sheet S3 are captured by an imaging device, and images are subjected to a binarization process to calculate the total area ratio of the foreign matter C to the area of ​​the inspection sheet S3, thereby identifying the proportion of the foreign matter C. Furthermore, the grade of the colored recycled resin pellets P2 may be set according to the identified proportion of the foreign matter C. [Explanation of symbols]

[0019] S1: Uncolored sheet, S2: Colored sheet, S3: Inspection sheet, C: Foreign matter

Claims

[Claim 1] A method for detecting foreign matter contained in colored recycled resin, comprising: A colored sheet production process for producing a colored sheet made of the colored recycled resin; a test sheet preparation step of sandwiching the prepared colored sheet between a pair of uncolored sheets made of uncolored resin, and heat-pressing the colored sheet and the pair of uncolored sheets so that the colored recycled resin and the uncolored resin are mixed to prepare a test sheet; a foreign matter detection step of detecting the foreign matter contained in the test sheet; A method for detecting foreign matter in colored recycled resin, comprising:

Images