Resin recovery method

Abstract

To provide a method for recovering more resin contained in ASR (Automobile Shredder Residue).SOLUTION: There is provided a resin recovery method for recovering a specific resin from ASR (Automobile Shredder Residue) containing multiple types of resin. The resin recovery method includes a resin sorting and recovery process in which the ASR is put into a liquid, and the specific resin is selected from a sedimented resin by specific gravity.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a method for recovering resin from ASR (automotive shredder dust), which is generated in large quantities when automobiles are scrapped. [Background technology]

[0002] Traditionally, end-of-life vehicles were processed by pressing and shredding after batteries, engines, tires, and other valuable parts were removed, and then recycled as scrap metal and non-ferrous metal. During this shredding process, a large amount of ASR (Automotive Surplus Residue) is generated, which is a mixture of plastics, rubber, iron, aluminum, copper, etc. This ASR is separated according to the Automobile Recycling Law, and metals, non-ferrous metals, and glass are being recycled. However, ASR contains more than 33% of multiple types of resins (plastics), but these resins are difficult to recycle and were either disposed of in landfills or burned / melted in waste incinerators.

[0003] In recent years, there has been growing expectation to recover and reuse the resin contained in ASR (Actual Substrate Removal). As a technology for recovering resin from ASR, for example, a technology has been disclosed that involves grading the resin group that floats using specific gravity fractionation with a liquid, according to the amount of inorganic filler components such as talc (see Non-Patent Documents 1 and 2). As shown in Non-Patent Documents 1 and 2, the resin group that settles after specific gravity fractionation using a liquid such as water accounts for approximately 55% of the total resin contained in ASR. However, compared to the floating resin, which is mostly polyolefin resin, the resin has a complex component composition and is mostly black, making separation difficult. Therefore, the entire amount has not been recovered and has been incinerated as raw material for cement, etc. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Report on the FY2015 Low-Carbon 3R Technology and System Demonstration Project (Development of a System for Material Recycling from ASR) (February 29, 2016, Toyota Tsusho Corporation, https: / / www.env.go.jp / recycle / car / pdfs / h27_report01_mat05.pdf) [Non-Patent Document 2] Optimization of the Recycling Process from ASR Recovered Resin: Development of an Advanced Sorting Scheme for Automotive-Derived Resins - Report (July 2018, Veolia Jenets Co., Ltd., https: / / www.nissan-global.com / JP / ENVIRONMENT / A_RECYCLE / R_FEE / SAISHIGEN / 2017 / PDF / report_asr_recovery_resin_recycle_process.pdf) [Overview of the project] [Problems that the invention aims to solve]

[0005] This invention has been made in view of these circumstances, and the object of this invention is to provide a method for recovering more resin contained in ASR. [Means for solving the problem]

[0006] The inventors of the present invention conducted intensive research to solve the above problems and found that the above problems can be solved by adding ASR to a liquid, recovering the resin that separates and settles due to its specific gravity, and then selecting a specific resin from the recovered resin. This led to the completion of the present invention.

[0007] In other words, the present invention is as follows: [1] A resin recovery method for recovering a specific resin from an ASR containing multiple types of resins, A resin recovery method characterized by comprising a resin sorting and recovery step of adding the ASR to a liquid and selecting a specific resin from the resin that has separated and settled according to its specific gravity.

[0008] [2] The resin recovery method according to [1] above, characterized in that the resin sorting in the resin sorting and recovery step is performed using an optical identification device. [3] The resin recovery method according to [2] above, characterized in that the optical identification device is an image identification device. [4] The resin recovery method according to [2] above, characterized in that the optical identification device is a spectroscopic analyzer. [5] The resin recovery method according to [4] above, characterized in that the spectroscopic analyzer is at least one selected from a Raman scattering optical identifier, a mid-infrared absorption optical identifier, and a near-infrared absorption optical identifier. [6] The resin recovery method according to any one of [1] to [5] above, characterized in that the specific resin to be sorted in the resin sorting and recovery step is at least one resin selected from high-rigidity polyolefin resin, polystyrene resin, and nylon resin. [7] A resin recovery method according to any one of [1] to [6] above, characterized by having an iron oxide-containing resin removal step before the resin sorting and recovery step, which removes iron oxide-containing resins from the resins separated and settled by specific gravity.

[0009] [8] A method for producing resin pellets, characterized by having a pelletizing step of processing the resin recovered by any of the resin recovery methods described in [1] to [7] above into pellets. [9] The method for producing resin pellets according to [8] above, characterized in that the pelletizing process is performed using a tandem extruder in the pelletizing step. [Effects of the Invention]

[0010] According to the resin recovery method of the present invention, a larger amount of resin contained in ASR can be recovered. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows a flow chart (example) of a resin recovery method according to one embodiment of the present invention. [Figure 2] This is a photograph of the resin used for sorting resin using the image recognition device in preliminary test 1. [Figure 3] It is an explanatory diagram of the screening method used in Preliminary Test 1. [Figure 4] It is a diagram showing the data of discrimination scores used in Preliminary Test 1. [Figure 5] It is a diagram showing the discrimination result using the data of discrimination scores in FIG. 4. [Figure 6] It is a diagram showing the Raman scattering spectrum data of each resin used in Preliminary Test 2, and shows the Raman scattering spectrum data of 25% talc-containing PP. [Figure 7] It is a diagram showing the Raman scattering spectrum data of each resin used in Preliminary Test 2, and shows the Raman scattering spectrum data of PP. [Figure 8] It is a diagram showing the Raman scattering spectrum data of each resin used in Preliminary Test 2, and shows the Raman scattering spectrum data of ABS. [Figure 9] It is a diagram showing the Raman scattering spectrum data of each resin used in Preliminary Test 2, and shows the Raman scattering spectrum data of nylon resin. [Figure 10] It is a diagram showing the Raman scattering spectrum data of PP with different talc contents used in Preliminary Test 2. From top to bottom in descending order of the value at 500 cm-1, it shows 50% talc-containing PP, 40% talc-containing PP, 30% talc-containing PP, 20% talc-containing PP, talc, 10% talc-containing PP, and PP. [Figure 11] It is a diagram showing the mid-infrared absorption spectrum data of each resin used in Preliminary Test 2. From top to bottom in descending order of the value at 3.85 μm, it shows nylon resin, ABS, PVC, and 25% talc-containing PP. [Figure 12] It is a diagram showing the near-infrared absorption spectrum data of each resin used in Preliminary Test 2. From top to bottom, it shows nylon resin, PP, 25% talc-containing PP, and ABS.

Mode for Carrying Out the Invention

[0012] The present invention relates to a resin recovery method for recovering a specific resin from ASR containing multiple types of resins, and is characterized by comprising a resin sorting and recovery step in which the ASR is placed in a liquid and the specific resin is selected from the resins that have separated and settled according to their specific gravity. The term "resin recovery method" in this invention is synonymous with "resin manufacturing method," and the effects of this right extend to resins recovered by the recovery method of this invention.

[0013] According to the resin recovery method of the present invention, it is possible to recover resins contained in ASR that were not previously recovered, thereby recovering more resin from ASR. In particular, it is possible to recover specific resins contained in resin that has separated and settled due to the specific gravity of the liquid.

[0014] The ASR of the present invention is a mixture of combustible materials such as plastics, rubbers, fabrics, and sponges contained in interior materials such as seats and dashboards of automobiles, and non-combustible materials such as glass fragments and metals and non-ferrous metals that could not be recovered. The ASR contains approximately 33% resin. Of this, polyolefin resins such as polypropylene resin (PP) and polyethylene resin (PE) make up about 72%, polystyrene resins such as ABS resin and polystyrene resin (PS) make up about 11%, and other resins such as nylon resin, polyvinyl chloride resin (PVC), polyacetal resin (POM), polybutylene terephthalate resin (PBT), polyacrylic resin (PMMA), and resins mixed with carbon fibers make up about 10%.

[0015] While there are no particular restrictions on the size (maximum width) of ASR used for resin recovery, it is usually 100 mm or less, preferably 5 to 80 mm, more preferably 10 to 60 mm, and even more preferably 20 to 50 mm. Within this range, errors in specific gravity separation due to increases or decreases in resin deposits within the ASR can be reduced. Furthermore, it eliminates the need for large processing equipment, thus reducing costs. If the maximum width of the ASR exceeds 100 mm, it is preferable to crush it before use.

[0016] As described above, the resin recovery method of the present invention is not particularly limited as long as it has a resin sorting and recovery step in which ASR is added to a liquid and a specific resin is selected from the resin separated and settled by specific gravity, and other steps may also be included. As shown in Figure 1, an example of the resin recovery method of the present invention is one which has a liquid specific gravity separation step (S1) in which ASR is added to a liquid and separated by specific gravity, an iron oxide-containing resin removal step (S2) in which iron oxide-containing resin is removed from the resin separated and settled by specific gravity, and a resin sorting and recovery step (S3) in which a specific resin is selected from the resin separated and settled in the liquid specific gravity separation step.

[0017] [Resin sorting and recovery process] The resin sorting and recovery process involves adding ASR to a liquid and sorting a specific resin from the resin that separates and settles based on its specific gravity. The specific gravity of the liquid into which the ASR is added is, for example, about 0.95 to 1.10, preferably 1.00 to 1.08, more preferably 1.00 to 1.06, and even more preferably 1.00 to 1.05. The liquid is not particularly limited and can be, for example, water or a liquid adjusted with a specific gravity adjusting agent such as calcium chloride.

[0018] Examples of specific resins to be sorted in the resin sorting and recovery process include polyolefin resins, polystyrene resins, nylon resins, polyvinyl chloride (PVC), polyacetal (POM), polybutylene terephthalate (PBT), and polyacrylic resins (PMMA). Preferably, high-rigidity polyolefin resins, polystyrene resins, and nylon resins are used.

[0019] High-rigidity polyolefin resin is talc-containing PP (polypropylene) with a talc content of 18% or more. Specifically, this includes medium-talc-containing PP with a talc content of 18-25% and high-talc-containing PP with a talc content of 25% or more. Talc-containing PP with a talc content of 18% or more is black, has a specific gravity of approximately 1.04-1.07, a flexural elastic strength of 1400 MPa or more, and a Charpy impact strength of 8 kJ / m². 2 It possesses the characteristics described above.

[0020] Polystyrene resins include, for example, ABS and PS, and these ABS and PS are usually mixed in ASR.

[0021] Nylon resin can be found, for example, in sheet form within ASR, or as tire-shaped components within ASR.

[0022] The resin sorting process in the resin sorting and recovery process is not particularly limited as long as it is possible to select a specific resin from the resin separated and settled by specific gravity, and a method using an optical identification device is preferred, for example. Examples of optical identification devices include image identification devices and spectroscopic analyzers, and the resin sorting of the present invention may be performed by combining these devices.

[0023] Resin sorting using an image recognition device involves extracting, analyzing, and identifying characteristics such as color, shape, and gloss of the resin contained in the ASR from image data captured from the ASR, thereby sorting the type of resin contained in the ASR. This method using an image recognition device makes it possible to sort black resins, which are more difficult to sort than white resins. Since this sorting can be performed by installing the image recognition device on the manufacturing line, it is possible to process large quantities of resins. The image recognition device may also utilize AI (artificial intelligence) for image recognition.

[0024] Specifically, resin sorting using an image recognition device can be performed by methods such as identifying resins based on color information (RGB values, HSV values, etc.) acquired from an image of the resin, or identifying resins based on the shape of the resin as it appears in the image. The former method, using color information, makes it possible to sort black resins contained in ASR, such as high-rigidity polyolefin resins, polystyrene-based resins such as ABS and PS, and nylon resin. The latter method, using shape, makes it possible to distinguish resins with specific shapes, such as nylon resin present as tire-shaped parts in ASR. A preferred method for identifying resins based on color information acquired from an image of the resin according to the present invention can be performed by converting RGB values ​​from the RGB color system to HSV values ​​from the HSV color system, and then using a discrimination score obtained by combining feature quantities such as the mean, standard deviation, and median of these HSV values.

[0025] Resin sorting using a spectroscopic analyzer involves irradiating the target ASR with light and analyzing the attenuation of scattered and reflected light to sort the types of resins contained in the ASR. This sorting is based on pre-acquired data and can sort composite materials consisting of multiple components based on their component ratios or characteristic wavelength ranges. Specifically, for example, it can sort black resins, which are more difficult to sort than white resins in ASR, by type, or sort high-rigidity polyolefin resins in ASR based on their talc content. Examples of spectroscopic analyzers include Raman scattering optical identification systems, mid-infrared absorption optical identification systems, and near-infrared absorption optical identification systems. Multiple spectroscopic analyzers may be used in combination.

[0026] Specifically, resin sorting using a spectroscopic analyzer can be performed in the following ways: Irradiating resin separated and settled by specific gravity with a single-wavelength laser, measuring the Raman scattering spectrum of the scattered light, and comparing it with previously acquired Raman scattering spectrum data for each type of resin to identify a specific resin (using a Raman scattering optical identification device); irradiating resin separated and settled by specific gravity with mid-infrared light, measuring the mid-infrared absorption spectrum of the attenuated reflected light, and comparing it with previously acquired mid-infrared absorption spectrum data for each type of resin to identify a specific resin (using a mid-infrared absorption optical identification device); or irradiating resin separated and settled by specific gravity with near-infrared light, measuring the near-infrared absorption spectrum of the attenuated reflected light, and comparing it with previously acquired near-infrared absorption spectrum data for each type of resin to identify a specific resin (using a near-infrared absorption optical identification device). This allows for more accurate sorting of resins. Furthermore, it enables the sorting of black resins, which are more difficult to sort than white resins.

[0027] The sorting method, which combines resin sorting using the image recognition device described above with resin sorting using a spectroscopic analyzer, specifically involves installing an image recognition device on the production line to sort the resins contained in ASR into high-rigidity polyolefin resin, nylon resin, and other resin groups. Subsequently, the sorted high-rigidity polyolefin resin is further sorted by talc content using a spectroscopic analyzer. The sorted other resin groups are then sorted by type using a spectroscopic analyzer. By using the image recognition device and spectroscopic analyzer in combination in this way, it becomes possible to sort many types of resins without omission and to sort efficiently, enabling mass processing. Furthermore, as mentioned above, the image recognition device is capable of mass processing, so it is possible to efficiently sort by changing the number of resin types sorted in each sorting step, such as sorting many types of resins with the image recognition device and sorting the remaining resins with the spectroscopic analyzer.

[0028] The resin recovery method of the present invention may include other steps before and after the resin sorting and recovery step described above. Other steps include the iron oxide-containing resin removal step described later.

[0029] While exploring ways to recover resin contained in ASR, the inventors discovered that ASR contains black iron oxide, a metal. Specifically, when using resins containing metals as resin materials, it is necessary to clearly distinguish them from resins that do not contain metals. However, it was found that black iron oxide-containing PP (polypropylene) was present in the ASR that separated and settled due to specific gravity. The fact that ASR contains black iron oxide, a metal, was not anticipated because metals are usually removed from ASR beforehand by magnetic separation at shredder plants. Furthermore, since the specific gravity of black iron oxide-containing PP is similar to that of polystyrene-based resins (ABS / PS) also contained in ASR that settle due to specific gravity separation, accurately separating and recovering them was difficult.

[0030] By separating and removing the black iron oxide contained in ASR using a magnetic separator with a stronger magnetic force than those used in shredder plants, the resin contained in ASR can be utilized to its fullest potential.

[0031] (Iron oxide-containing resin removal process) The iron oxide-containing resin removal step is a step performed before the resin sorting and recovery step described above, in which the iron oxide-containing resin is removed from the resin that has been separated and settled by specific gravity. The method for removing the iron oxide-containing resin is not particularly limited as long as it can remove the iron oxide-containing resin, but high magnetic separation treatment using a high magnetic separation device is preferred. The magnetic force strength for the high magnetic separation treatment is preferably 5,000 to 20,000 gauss, more preferably 8,000 to 15,000 gauss, and even more preferably 10,000 to 12,000 gauss. This makes it possible to remove the iron oxide-containing resin that could not be removed by the normal magnetic separation (approximately 3,000 to 5,000 gauss) performed in a shredder factory.

[0032] The iron oxide-containing resin removal process may be performed before, after, or both before and after separation by specific gravity, but it is preferable to perform it at least after separation by specific gravity. This makes it possible to recover high-quality black iron oxide-containing PP with fewer metals other than black iron oxide-containing PP from the treated material removed from the resin recovered by separation by specific gravity. The recovered black iron oxide-containing PP can be used as a raw material for large molded products.

[0033] The resin recovered by the resin recovery method of the present invention described above (the specific resin selected in the resin sorting and recovery process) is preferably at least one resin selected from high-rigidity polyolefin resin, polystyrene resin, and nylon resin. The properties of each resin are the same as those of the resin separated and settled according to the specific gravity described above. Furthermore, the resin recovered by the resin recovery method of the present invention can be used as a recycled material and can be used, for example, as a material for packaging materials such as containers, or building materials such as flooring and wall materials.

[0034] [Method for manufacturing resin pellets] The resin recovered by the resin recovery method of the present invention can be used as a raw material for resin products in its unprocessed state, or it can be molded and used as a raw material for resin products (see Figure 1). When molded and used as a raw material for resin products, examples of molding methods include pelletizing, sheeting, and filming, with pelletizing being preferred so that it can be used for various applications when reused. Furthermore, it is preferable to perform composite material molding to impart high functionality to the resin recovered by the resin recovery method of the present invention. As an example of a method to impart high functionality, carbon fibers such as used carbon fibers can be mixed to create a carbon fiber-containing resin. This makes it possible to impart functions such as improved strength, electromagnetic shielding ability, and antistatic ability to the resin.

[0035] The method for producing the resin pellets of the present invention will be described below. The present invention's method for producing resin pellets is characterized by comprising a pelletizing step of processing the resin recovered by the above-described resin recovery method into pellets.

[0036] (Pellet processing process) The extruder used for pellet processing is not particularly limited and can include, for example, a single-screw extruder, a twin-screw extruder, a vented extruder, a tandem extruder, etc., but a tandem extruder is preferred. This allows for the complete removal of fine impurities adhering to the resin using a metal mesh or the like in the first stage, and the production of high-quality pellets from the resin from which the impurities have been removed in the second stage. Furthermore, tandem extruders are less prone to problems such as clogging. The pelletizer method used for pellet processing is not particularly limited and can include, for example, an underwater cutting method, a hot cutting method, a strand cutting method, etc., but a strand cutting method is preferred. This allows for the production of high-purity, high-quality pellets. [Examples]

[0037] The present invention will be described in detail below with reference to examples, but these examples are not intended to limit the scope of the present invention.

[0038] First, using specific resins included in the group of resins that separated and settled due to the specific gravity of ASR, we performed resin selection using discrimination scores with an image recognition device (preliminary test 1) and resin selection using a spectroscopic analyzer (preliminary test 2).

[0039] Here, Figure 2 is a photograph of the resin used for sorting using the image recognition device in Preliminary Test 1, Figure 3 is an explanatory diagram of the sorting method used in Preliminary Test 1, Figure 4 is a diagram showing the discrimination score data used in Preliminary Test 1, and Figure 5 is a diagram showing the discrimination results using the discrimination score data from Figure 4. Figures 6 to 10 show the Raman scattering spectral data of each resin used in Preliminary Test 2, Figure 6 shows the Raman scattering spectral data of 25% talc-containing PP, Figure 7 shows the Raman scattering spectral data of PP, Figure 8 shows the Raman scattering spectral data of ABS, Figure 9 shows the Raman scattering spectral data of nylon resin, and Figure 10 shows the Raman scattering spectral data of PP with different talc content. Figure 11 shows the mid-infrared absorption spectral data in Preliminary Test 2, from top to bottom showing nylon resin, ABS, PVC, and 25% talc-containing PP. Figure 12 shows the near-infrared absorption spectrum data from preliminary test 2, with nylon resin, PP, 25% talc-containing PP, and ABS shown from top to bottom.

[0040] [Preliminary Examination 1] (Sorting of resins using an image recognition device) As shown in Figure 2, specific resins included in the group of resins that separated and settled due to the specific gravity of ASR were photographed. Specifically, the resins that settled due to ASR specific gravity fractionation were 25% talc-containing PP (high-rigidity polyolefin resin, sample numbers No. 9-13), ABS (polystyrene-based resin, sample numbers No. 1-2), and PC (sample number No. 3). For reference, 5% talc-containing PP (sample number No. 4) and 15% talc-containing PP (sample numbers No. 5-8) were used as resins that floated due to ASR specific gravity fractionation. Subsequently, as shown in Figure 3, RGB values ​​in the RGB color system were obtained from the images of the captured resins.

[0041] Next, as shown in Figure 4, the RGB values ​​obtained from the images of each resin (sample numbers No. 1 to 13) were converted to HSV values ​​in the HSV color system, and a discrimination score was obtained by combining feature quantities such as the mean, standard deviation, and median of the HSV values. As shown in Figure 5, it was confirmed that the obtained discrimination score DS could be used to distinguish between 25% talc-containing PP and the other resin groups (ABS, PC).

[0042] [Preliminary Examination 2] (Selection of resins using a spectroscopic analyzer 1) Using a Raman scattering optical identification device (manufactured by SIEM Co., Ltd.), Raman scattering spectral data were measured for 25% talc-containing PP (high-rigidity polyolefin resin), PP (talc-free PP), ABS, and nylon resin. The results are shown in Figures 6-9.

[0043] The Raman scattering spectral data for each resin has peaks that characterize each resin (indicated by circles in each figure). Specifically, as shown in Figures 6 and 7, at 600 cm²... -1 The counts were approximately 50,000 for PP containing 25% talc and approximately 10,000 for PP (talc-free PP), at 600 cm². -1 By checking the count in this area, resin sorting is possible. Also, as shown in Figure 8, ABS is 1000 cm -1 and 2200cm -1 By identifying characteristic peaks that appear in the vicinity, resin sorting is possible. Furthermore, as shown in Figure 9, nylon resin is present at 1350 cm². -1 and 1750cm -1 By identifying characteristic peaks that appear in the vicinity, resin sorting becomes possible. From the above, we confirmed that resins can be sorted using Raman scattering spectral data obtained from a Raman scattering optical identification device.

[0044] In addition, using a Raman scattering optical discrimination device (manufactured by Sym Corporation), Raman scattering spectrum data of PP with different talc contents were measured. The talc contents of each PP used were 20%, 30%, 40%, and 50%. For comparison, Raman scattering spectrum data of pure PP, pure talc, and 10% talc-containing PP, which is a resin that floats by specific gravity separation of ASR, were measured. The results are shown in FIG. 10. Each graph in FIG. 10 shows, from top to bottom in descending order of the value at 500 cm -1 50% talc-containing PP, 40% talc-containing PP, 30% talc-containing PP, 20% talc-containing PP, talc, 10% talc-containing PP, and PP. As shown in FIG. 10, it was confirmed that the talc content of PP can be identified by discriminating the height of the peak rise that appears up to 500 cm -1 using a calibration curve.

[0045] (Selection of Resin Using a Spectroscopic Analyzer 2) Using a mid-infrared absorption spectroscopic device (manufactured by Sym Corporation), mid-infrared absorption spectrum data of 25% talc-containing PP (high-rigidity polyolefin resin), ABS (polystyrene resin), nylon resin, and PVC (polyvinyl chloride resin) were measured. The results are shown in FIG. 11. Each graph in FIG. 11 shows, from top to bottom in descending order of the value at 3.85 μm, nylon resin, ABS, PVC, and 25% talc-containing PP.

[0046] The arrows in FIG. 11 indicate the peaks that characterize 25% talc-containing PP, ABS, and nylon resin. It was found that resin selection is possible by confirming these characteristic peaks. Specifically, 25% talc-containing PP has a characteristic peak at a wavelength of 3.37 μm, ABS has a characteristic peak at a wavelength of 3.29 μm, and nylon resin has a characteristic peak at a wavelength of 3.03 μm. In addition, PVC can be distinguished from other resins by giving a narrow peak with less structure at a wavelength of 3.4 - 3.5 μm. From the above, it was confirmed that resins can be selected using mid-infrared absorption spectrum data obtained using a mid-infrared absorption spectroscopic device.

[0047] (Selection of resins using a spectroscopic analyzer 3) Near-infrared absorption spectral data were measured for 25% talc-containing PP (high-rigidity polyolefin resin), ABS (polystyrene-based resin), nylon resin, and PP (talc-free PP) using a near-infrared absorption spectrometer (manufactured by SIEM Co., Ltd.). The results are shown in Figure 12. The graphs in Figure 12, from top to bottom, represent nylon resin, PP, 25% talc-containing PP, and ABS.

[0048] The arrows in Figure 12 indicate peaks characteristic of 25% talc-containing PP, ABS, and nylon resin. It was found that resin sorting is possible by identifying these characteristic peaks. Specifically, 25% talc-containing PP has characteristic peaks around wavelengths of 2300 nm and 2500 nm, ABS has characteristic peaks around wavelengths of 2300 nm and 2500 nm, and nylon resin has characteristic peaks around wavelengths of 2050 nm and 2300 nm. From the above, we confirmed that resins can be sorted using near-infrared absorption spectral data obtained from a near-infrared absorption spectrometer.

[0049] <Examples> A specific resin was recovered from ASR using the resin recovery method of the present invention. 100 kg of ASR was added to 1000 L of water adjusted to a specific gravity of approximately 1.05 (final specific gravity), and the resin that separated and settled due to specific gravity (separated and settled resin group) was recovered.

[0050] Next, resins containing iron oxide were removed from the separated and settled resin group (iron oxide-containing resin removal process). Specifically, a high-magnetic-force separation device with a magnetic field strength of 10,000 gauss was used to remove black iron oxide-containing PP. This allowed us to separate approximately 1.3 kg of black iron oxide-containing PP.

[0051] (Sorting of resins using an image recognition device) Next, the separated and settled resins were sorted using an image recognition device. Specifically, similar to the resin sorting using the image recognition device in preliminary test 1, the resins were sorted into high-rigidity polyolefin resins and other resin groups (ABS, nylon resin, PVC, etc.) using the discrimination score DS. This allowed for the separation of the resin into high-rigidity polyolefin resin and other resin groups (polystyrene-based resin (ABS), nylon resin, PVC, etc.).

[0052] (Selection of resins using a spectroscopic analyzer) Next, the resins that were sorted into the other resin group by the image recognition device were further sorted using a spectroscopic analyzer. Specifically, similar to the resin sorting 2 using a spectroscopic analyzer in preliminary test 2, we used Raman scattering spectral data obtained from a Raman scattering optical recognition device to sort the resins that had been sorted into other resin groups by the image recognition device. This allowed for sorting into polystyrene-based resin (ABS), nylon resin, and PVC.

[0053] Furthermore, the resins sorted into high-rigidity polyolefin resins by the image recognition device were sorted by talc content, similar to the resin sorting 1 using the spectroscopic analyzer described above. Specifically, similar to the resin sorting using a spectroscopic analyzer in preliminary test 2, the resins separated into high-rigidity polyolefin resins by an image recognition device were sorted by talc content using Raman scattering spectral data obtained from a Raman scattering optical recognition device. This allowed for the separation of high-rigidity polyolefin resin into medium-talc-containing PP (18-25%) and high-talc-containing PP (25% or more). Thus, by using the resin recovery method of the present invention, high-rigidity polyolefin resin can be separated according to its talc content, enabling the supply of PP separated by talc content, or the supply of mixtures of PP with different talc content at a constant mixing ratio.

[0054] It has been found that using the resin recovery method of the present invention, high-rigidity polyolefin resins (medium-talc PP, high-talc PP), polystyrene resins, nylon resins, and PVC, each with a different talc content, can be recovered from resins separated and settled by specific gravity fractionation using liquids. Specifically, the settled resins included approximately 24% medium-talc-containing PP (talc content less than 18-25%), approximately 8% high-talc-containing PP (talc content of 25% or more), approximately 11% polystyrene-based resin (ABS), approximately 4% nylon resin, and approximately 6% other resins (PVC, etc.). The water-floating resin consisted of approximately 24% PP, approximately 14% low-talc PP (talc content less than 18%), and approximately 7% PE.

[0055] (Manufacturing of resin pellets) Next, resin pellets were manufactured using the resin recovered by the above resin recovery method. Specifically, the high-rigidity polyolefin resin recovered using the resin recovery method was processed into pellets using a tandem extruder. The pelletizer used for pellet processing employed a strand-cutting method.

[0056] It has been found that pellets obtained using the resin pellet manufacturing method of the present invention have few impurities and high purity. Furthermore, because the pellets are of high purity, they can be used as recycled materials and as building materials such as flooring and wall coverings. [Industrial applicability]

[0057] The resin recovery method of the present invention is industrially useful because it allows for the recovery of reusable resin from ASR.

Claims

1. A step of removing iron oxide-containing resins by adding ASR containing multiple types of resins from which metals have been removed in advance to a liquid, and removing the resin containing iron oxides from the resins that have separated and settled due to specific gravity, The process includes a resin sorting and recovery step that selects specific resins from resins from which resins containing iron oxide have been removed. The resin sorting in the aforementioned resin sorting and recovery process is performed using an optical identification device, which is an image identification device and a spectroscopic analyzer. A method for manufacturing resin pellets, characterized by comprising a pelletizing step for processing the resin sorted and recovered in the aforementioned resin sorting and recovery step into pellets.

2. The method for producing resin pellets according to claim 1, characterized in that the spectroscopic analyzer is at least one selected from a Raman scattering optical identifier, a mid-infrared absorption optical identifier, and a near-infrared absorption optical identifier.

3. The method for producing resin pellets according to claim 1 or 2, characterized in that the specific resin to be sorted in the resin sorting and recovery step is at least one resin selected from high-rigidity polyolefin resin, polystyrene resin, and nylon resin.

4. The spectroscopic analyzer is a Raman scattering optical identification device, and the specific resin to be sorted in the resin sorting and recovery process is a high-rigidity polyolefin resin, A method for producing resin pellets according to claim 3, characterized by sorting high-rigidity polyolefin resin according to its talc content.

5. The method for producing resin pellets according to claim 1, characterized in that the pelletizing process is performed using a tandem extruder in the pelletizing step.

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