Method for manufacturing resin compositions

Abstract

To provide a method for producing a resin composition using a thermoplastic resin material containing metal, which has a high yield and excellent extrudeability during melt-kneading. [Solution] The method for producing a resin composition according to the present disclosure includes the steps of: putting a thermoplastic resin material (A) containing metal and other components into an extruder and melt-kneading them to obtain resin pellets (B); reducing the amount of metal in the thermoplastic resin material (A) or resin pellets (B) using a magnet; and reducing the amount of metal in the thermoplastic resin material (A) or resin pellets (B) using a metal detector, wherein the step of reducing the amount of metal in the pellets using a metal detector is performed after the step of reducing the amount of metal in the pellets using a magnet.

Description

Technical Field

[0001] The present invention relates to a method for producing a resin composition. In particular, it relates to a method for producing a resin composition using waste materials of thermoplastic resins.

Background Art

[0002] Conventionally, thermoplastic resins have been molded into various molded products. On the other hand, in recent years, the reuse of resources has been strongly demanded, and the recycling of thermoplastic resins has also been studied. Here, waste materials of thermoplastic resins usually contain components other than thermoplastic resins such as resin additives. Here, if the waste material of the thermoplastic resin contains a metal component, various adverse effects will be exerted on a new molded product formed from the thermoplastic resin derived from such waste material. Therefore, methods for producing resin compositions using thermoplastic resin materials containing metals have been studied (Patent Documents 1, 2, etc.).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described above, methods for removing metal components from thermoplastic resin materials have been studied. However, with the promotion of the recycling of thermoplastic resins, the yield of the resin composition obtained after removing metal from the thermoplastic resin material has been low, or there has been a tendency to require improvement in the extrusion property when melt-kneading the thermoplastic resin material containing metal and other components. The present invention aims to solve the aforementioned problems and to provide a method for producing a resin composition using a thermoplastic resin material containing a metal, which has a high yield and excellent extrudeability during melt-kneading. [Means for solving the problem]

[0005] Based on the above problems, the inventors conducted research and found that the above problems can be solved by performing a step of reducing the amount of metal in a thermoplastic resin using a magnet and a step of reducing the amount of metal using a metal detector, and by performing the step of reducing the amount of metal using a metal detector after the step of reducing the amount of metal using a magnet. Specifically, the above problem was solved by the following means. [1] A process of putting a thermoplastic resin material (A) containing metal and other components into an extruder and melt-kneading them to obtain resin pellets (B), A step of reducing the amount of metal in a thermoplastic resin material (A) or resin pellet (B) containing the aforementioned metal using a magnet, The process includes reducing the amount of metal in a thermoplastic resin material (A) or resin pellet (B) containing the aforementioned metal using a metal detector. A method for manufacturing a resin composition, wherein the step of reducing the amount of metal in the pellets using the metal detector is performed after the step of reducing the amount of metal in the pellets using the magnet. [2] A method for producing a resin composition according to [1], wherein the step of reducing the amount of metal in the pellet using the magnet is performed on a thermoplastic resin material (A) containing metal. [3] A method for producing a resin composition according to [1] or [2], wherein the step of reducing the amount of metal in the pellet using the metal detector is performed on the resin pellet (B). [4] The process of reducing the amount of metal in the pellet using the magnet is performed on a thermoplastic resin material (A) containing metal, A method for producing a resin composition according to any one of [1] to [3], wherein the step of reducing the amount of metal in the pellet using the metal detector is performed on the resin pellet (B). [5] A method for producing a resin composition according to any one of [1] to [4], wherein the thermoplastic resin material (A) containing the metal is a resin pellet derived from waste material. [6] A method for producing a resin composition according to any one of [1] to [5], wherein the thermoplastic resin material (A) containing the metal comprises a magnetic metal and a non-magnetic metal. [7] A method for producing a resin composition according to any one of [1] to [6], wherein the thermoplastic resin material (A) containing the metal comprises a polystyrene resin. [8] The thermoplastic resin material (A) containing the metal is a resin pellet derived from waste material, The thermoplastic resin material (A) containing the aforementioned metal includes a magnetic metal and a non-magnetic metal. A method for producing a resin composition according to any one of [1] to [8], wherein the thermoplastic resin material (A) containing the aforementioned metal comprises a polystyrene resin. [9] A method for producing a resin composition according to any one of [1] to [8], wherein the step of reducing the amount of metal in the pellet using the magnet is performed using a magnet bar and / or a magnet roll separator. [Effects of the Invention]

[0006] The present invention provides a method for producing a resin composition that has a high yield and excellent extrudeability during melt-kneading. [Modes for carrying out the invention]

[0007] The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). Note that the following embodiment is illustrative for explaining the present invention, and the present invention is not limited to this embodiment. In this specification, "~" is used to mean that the numerical values ​​before and after it are included as the lower and upper limits. Furthermore, the upper and lower limits of the numerical values ​​in this specification are given as examples of this embodiment, regardless of the combination of upper and lower limits. In this specification, a preferred combination of embodiments is a more preferred embodiment. In this specification, all physical properties and characteristic values ​​shall be those at 23°C unless otherwise specified.

[0008] In this specification, unless otherwise specified, weight-average molecular weight and number-average molecular weight are polystyrene-converted values ​​measured by GPC (gel permeation chromatography). In this specification, the term "process" includes not only independent processes but also any process that is not clearly distinguishable from other processes, as long as its intended function is achieved. If the measurement methods, etc., described in the standards shown in this specification differ from year to year, unless otherwise specified, the standards as of January 1, 2024 shall apply. If the measurement methods, etc., described in the standards shown in this specification have been discontinued as of January 1, 2024, the standards in effect at the time of discontinuation shall apply. In this embodiment, metal analysis in the resin can be performed by ICP emission spectroscopy.

[0009] The method for producing the resin composition of this embodiment includes the steps of: putting a thermoplastic resin material (A) and other components into an extruder and melt-kneading them to obtain resin pellets (B); reducing the amount of metal in the thermoplastic resin material (A) or resin pellets (B) containing metal using a magnet; and reducing the amount of metal in the thermoplastic resin material (A) or resin pellets (B) containing metal using a metal detector, wherein the step of reducing the amount of metal in the pellets using a metal detector is performed after the step of reducing the amount of metal in the pellets using a magnet. By adopting this configuration, it is possible to produce a resin composition that has a high yield after removing metal components from the thermoplastic resin material, and also exhibits excellent extrudeability when the resin composition is melt-kneaded. When thermoplastic resin materials containing metal (e.g., resin pellets) are melt-kneaded, wear inside the melt-kneading apparatus due to the metal, and vent-up problems due to metal clogging the screen mesh during extrusion and increased resin pressure tend to occur, resulting in poor extrudeability. Therefore, it is conceivable to treat the resin pellets containing metal with a metal detector to remove the metal components. However, when resin pellets containing metal are subjected to a metal detector, not only the metal-containing resin pellets but also the surrounding non-metal-containing pellets are removed. In other words, the metal detector for resin pellets operates to remove not only the resin pellets in which metal is detected, but also the non-metal-containing resin pellets in the area where metal was detected. As a result, the yield of the final resin composition is low. In this embodiment, it is presumed that the yield of the final resin composition could be improved by performing a magnetic treatment on the resin pellets containing metal to remove resin pellets containing magnetic metal components, and then treating them with a metal detector.

[0010] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is just one example of an embodiment of the present invention and is not limited to these.

[0011] The method for producing the resin composition of this embodiment includes the step of putting a thermoplastic resin material (A) and other components into an extruder and performing melt-kneading to obtain resin pellets (B). The thermoplastic resin material (A) (in this specification, sometimes simply referred to as "the thermoplastic resin material (A) containing metal") is, for example, resin pellets and is resin pellets derived from waste materials. Such waste materials include recycled products (including recovered products, material recycled products, chemical recycled products, etc.), defective products, scraps generated when molding molded products from resin compositions, unused stored products, and the like. Recycled products include, for example, home appliances, food trays, yogurt containers, fishing nets, fiber materials, automotive airbags, water bottles, beverage bottles, building materials, heat insulation materials, automotive exterior parts, automotive interior parts, headlamp covers, and the like.

[0012] The metal contained in the thermoplastic resin material (A) containing metal may be a magnetic metal or a non-magnetic metal, and examples include those containing both a magnetic metal and a non-magnetic metal. Examples of magnetic metals include iron, cobalt, nickel, etc., and it is exemplified that it contains iron. Non-magnetic metals are metals other than magnetic metals, and examples include aluminum, gold, silver, palladium, copper, tin, etc., and it is exemplified that it contains aluminum.

[0013] The amount of metal contained in the thermoplastic resin material (A) containing metal is, for example, 3% by mass or more, and may be 5% by mass or more, and usually, it is preferably 1% by mass or less.

[0014] The thermoplastic resin material (A) usually contains a thermoplastic resin. Examples of thermoplastic resins include polystyrene resins; polycarbonate resins; polyester resins (thermoplastic polyester resins); polyamide resins; polyolefin resins such as polyethylene resins, polypropylene resins, and cyclic olefin resins; polyacetal resins; polyimide resins; polyetherimide resins; polyurethane resins; polyphenylene ether resins; polyphenylene sulfide resins; polysulfone resins; polymethacrylate resins; etc., and it is preferable to contain polystyrene resins.

[0015] Details of the above thermoplastic resin can be considered based on the descriptions in paragraphs 0010 to 0052 of JP-A No. 2022-008175, paragraphs 0016 to 0043 of JP-A No. 2022-28718, and paragraphs 0011 to 0024 of JP-A No. 2024-054065, and the contents thereof are incorporated herein.

[0016] The content of the thermoplastic resin in the thermoplastic resin material (A) containing a metal is preferably 10% by mass or more, more preferably 50% by mass or more, still more preferably 80% by mass or more, may be 90% by mass or more, and is 100% by mass or less. The thermoplastic resin contained in the thermoplastic resin material (A) containing a metal may be only one kind or two or more kinds. In the case of two or more kinds, the total amount is preferably within the above range.

[0017] In addition to the above, the thermoplastic resin material (A) containing a metal may contain a filler and a resin additive that can be usually contained in a resin composition.

[0018] Details of the filler can be considered based on the descriptions in paragraphs 0056 to 0061 of JP-A No. 2022-011052 and paragraphs 0093 to 0102 of WO 2021 / 241471, and the contents thereof are incorporated herein. The amount of the filler contained in the thermoplastic resin material (A) containing a metal is preferably 0 to 50% by mass in the thermoplastic resin material (A) containing a metal, and may be a configuration that is substantially not contained. Substantially not contained means, for example, 3% by mass or less of the thermoplastic resin material (A) containing a metal.

[0019] Examples of the resin additive include an antioxidant, a heat stabilizer, a light stabilizer, a weather resistance stabilizer, a mold release agent, a flame retardant, an ultraviolet absorber, a dye, a pigment, an antistatic agent, an antifogging agent, an antiblocking agent, a fluidity improver, a plasticizer, a dispersant, an antibacterial agent, etc. Details of these can be considered based on the descriptions in paragraphs 0048 to 0052 of JP-A No. 2024-054065, paragraphs 0047 to 0092, and paragraph 0103 of WO 2021 / 241471, and the contents thereof are incorporated herein. The total amount of resin additives is preferably 0.1 parts by mass or more and less than 10 parts by mass, based on 100 parts by mass of the total thermoplastic resin contained in the thermoplastic resin material (A) containing metal. In this embodiment, the thermoplastic resin material (A) containing metal may contain only one type of resin additive, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range. In this embodiment, the metal-containing thermoplastic resin material (A) is preferably a metal-containing resin pellet. When it is a resin pellet, the effects of the present invention tend to be exhibited more effectively.

[0020] There are no particular restrictions on other components that are kneaded together with the thermoplastic resin material (A) containing metal. Other components include thermoplastic resins, fillers, resin additives, or resin compositions containing thermoplastic resins (pellets, masterbatches), etc. Other components are preferably virgin. Furthermore, other components are preferably metal-free or contain only trace amounts of metal. The upper limit of the amount of metal in other components is preferably less than 800 ppm by mass, more preferably less than 500 ppm by mass, and even more preferably less than 300 ppm by mass. The lower limit of the metal content in other components is 0 ppm by mass or more. Furthermore, the amount of metal in other components is preferably less than 500 ppm by mass in the final resin pellet (B), more preferably less than 300 ppm by mass, and even more preferably less than 100 ppm by mass. The lower limit of the metal content in the resin pellet (B) is 0 ppm by mass or more.

[0021] The resin pellet (B) is a molten mixture of a thermoplastic resin material (A) containing metal and other components. The resin pellets (B) typically contain a thermoplastic resin. Examples of thermoplastic resins include polystyrene resins; polycarbonate resins; polyester resins (thermoplastic polyester resins); polyamide resins; polyolefin resins such as polyethylene resins, polypropylene resins, and cyclic cycloolefin resins; polyacetal resins; polyimide resins; polyetherimide resins; polyurethane resins; polyphenylene ether resins; polyphenylene sulfide resins; polysulfone resins; and polymethacrylate resins. It is preferable that the pellets contain polyphenylene ether resin.

[0022] Details of the above thermoplastic resin can be found in paragraphs 0010 to 0052 of Japanese Patent Publication No. 2022-008175, paragraphs 0016 to 0043 of Japanese Patent Publication No. 2022-28718, and paragraphs 0011 to 0025 of Japanese Patent Publication No. 2024-054065, the contents of which are incorporated herein by reference.

[0023] The thermoplastic resin content of the resin pellets (B) is preferably 10% by mass or more, more preferably 50% by mass or more, and 100% by mass or less. The thermoplastic resin contained in the resin pellets (B) may be only one type or two or more types. If there are two or more types, it is preferable that the total amount is within the above range.

[0024] In addition to the above, the resin pellet (B) may also contain fillers and resin additives that are typically included in resin compositions.

[0025] Details of the filler can be found in paragraphs 0056 to 0061 of Japanese Patent Publication No. 2022-011052 and paragraphs 0093 to 0102 of International Publication No. 2021 / 241471, the contents of which are incorporated herein by reference. The amount of filler contained in the resin pellet (B) is 0% by mass or more, and may be 10% by mass or more, 30% by mass or more, depending on the application, and preferably 60% by mass or less, and more preferably 50% by mass or less. The resin pellet (B) may contain only one type of filler or two or more types. In the case of two or more types, it is preferable that the total amount is within the above range. Examples of resin additives include antioxidants, heat stabilizers, light stabilizers, weather stabilizers, mold release agents, flame retardants, ultraviolet absorbers, dyes, pigments, antistatic agents, antifogging agents, antiblocking agents, flow improvers, plasticizers, dispersants, and antibacterial agents. Details of these can be found in paragraphs 0048 to 0052 of Japanese Patent Publication No. 2024-054065, paragraphs 0047 to 0092, and paragraph 0103 of International Publication No. 2021 / 241471, the contents of which are incorporated herein by reference. The total amount of resin additives is preferably 0.1 parts by mass or more and less than 10 parts by mass, relative to 100 parts by mass of the total thermoplastic resin contained in the resin pellet (B). In this embodiment, the resin pellet (B) may contain only one type of resin additive, or it may contain two or more types. If it contains two or more types, it is preferable that the total amount is within the above range.

[0026] The method for producing the resin composition of this embodiment includes the step of putting a thermoplastic resin material (A) containing a metal and other components into an extruder and performing melt-kneading to obtain resin pellets (B). The mass ratio of the metal-containing thermoplastic resin material (A) to the other components is preferably 10:90 to 90:10, and more preferably 20:80 to 80:20. The extruder may be supplied with a thermoplastic resin material (A) containing metal and other components pre-mixed together, or the components may be supplied to the extruder using a feeder, either without pre-mixing them, or with only some of them pre-mixed. The extruder may be a single-screw extruder or a twin-screw extruder. Furthermore, when incorporating fillers (especially glass fibers), it is preferable to supply them from a side feeder located in the middle of the extruder cylinder. The heating temperature during melt mixing is determined considering the melting temperature of the thermoplastic resin, but it can usually be appropriately selected from the range of 170 to 350°C. The extruder may be equipped with a polymer filter and / or screen mesh. The screen mesh may be appropriately selected from #10, #20, #30, #40, #60, #80, #100, #150, #200, #250, #300, etc., and multiple meshes may be combined.

[0027] The method for manufacturing the resin composition of this embodiment includes a step of reducing the amount of metal in a metal-containing thermoplastic resin material (A) or resin pellet (B) using a magnet. By performing the step of reducing the amount of metal in the pellet using a magnet (sometimes referred to as "magnet treatment" in this specification), magnetic metal can be effectively reduced. In particular, since magnet treatment can detect and remove only the pellets containing metal, it becomes possible to manufacture the resin composition with a high yield. A magnet bar or a magnetic roll separator (MRS) is preferably used for magnet treatment. An example of a magnet bar is a grid-shaped magnet bar with a magnetic force rating of 10,000 gauss. A magnetic roll separator (MRS) is a method of separating non-separable substances using a so-called belt-type magnetic roll separator, in which an endless belt is placed between a magnet rod (magnetic roller) and a non-magnet rod (non-magnetic roller), and the substance to be separated is transported by the endless belt. Furthermore, an invention is disclosed that separates materials containing magnetic material from materials not containing magnetic material based on the relationship between the inertial force of the material to be separated generated by the conveying speed of the endless belt, the magnetic force of the magnet rod, and the weight of the material to be separated. As an example of the magnet treatment, refer to the description in Japanese Patent Application Publication No. 8-141432, which is incorporated herein by reference. In this embodiment, it is preferable to perform the magnetic treatment on a thermoplastic resin material (A) containing metal. By performing the treatment on a thermoplastic resin material (A) containing metal, the amount of metal during melt-kneading in the extruder can be reduced, and the extrudeability of the resin composition tends to improve. In particular, even when the extruder is equipped with a polymer filter and / or screen mesh, clogging of the polymer filter and / or screen mesh can be effectively suppressed, and the extrudeability of the resin composition can be further improved.

[0028] The method for producing the resin composition of this embodiment includes a step of reducing the amount of metal in a thermoplastic resin material (A) or resin pellet (B) containing metal using a metal detector. By performing the step of reducing the amount of metal in the pellet using a metal detector (sometimes referred to as "metal detector treatment" in this specification), non-magnetic metals can be effectively reduced in addition to magnetic metals. The metal detector is also called a metal detector or metal detector, and examples include the Metallider metal detector manufactured by Saiga Technical Research Institute, the RAPID COMPACT metal detector manufactured by SESTOTEC, the metal detector manufactured by MinebeaMitsumi, and the metal detector manufactured by Anritsu. In this embodiment, it is preferable to perform the metal detector treatment on the resin pellet (B). By performing the treatment on the resin pellet (B), the yield of the resulting resin composition can be increased.

[0029] In the resin composition manufacturing method of this embodiment, it is preferable that the step of reducing the amount of metal in the pellets using a metal detector is performed after the step of reducing the amount of metal in the pellets using a magnet. By performing the magnet treatment first, the amount of metal can be reduced while maintaining a high yield. Furthermore, by using a metal detector on resin pellets from which magnetic metal has been reduced, the probability of removing thermoplastic resin material or resin pellets that do not contain metal can be effectively reduced. In other words, if metal detection is performed on thermoplastic resin material or resin pellets as if they contain metal, the thermoplastic resin material or resin pellets in the area where metal was detected will be removed, resulting in a relatively lower yield of the final resin composition. In this embodiment, by performing metal detector treatment on magnet-treated thermoplastic resin material, a resin composition can be manufactured with a high yield. In the method for producing the resin composition of this embodiment, the magnetic treatment and the metal detector treatment may be performed once each, or more times. From the standpoint of production efficiency, it is preferable to perform the magnetic treatment and metal detector treatment once each. On the other hand, in order to improve the accuracy of metal removal, the magnetic treatment and / or metal detector treatment may be performed two or more times, without departing from the spirit of the present invention. For example, one example is to perform the treatment in the order of magnetic treatment, metal detector treatment, and then magnetic treatment again.

[0030] In this embodiment, it is preferable to perform the step of reducing the amount of metal in the pellets using a magnet on a thermoplastic resin material (A) containing metal, and the step of reducing the amount of metal in the pellets using a metal detector on resin pellets (B). With this configuration, a resin composition with high yield and superior moldability can be obtained. An example of a resin composition obtained by the manufacturing method of this embodiment is a resin pellet. However, the resin composition of this embodiment may also be molded directly after melt-kneading in an extruder, without the need for pellets. In this case, the resin composition becomes a molded product such as an injection-molded product or an extruded product.

[0031] The resin composition (pellets) obtained by the manufacturing method of this embodiment can be molded into new molded articles using various molding methods. There are no particular restrictions on the shape of the new molded articles, and they can be appropriately selected according to the use and purpose of the molded articles. Examples include film-shaped, rod-shaped, cylindrical, annular, circular, elliptical, polygonal, irregularly shaped, hollow, frame-shaped, box-shaped, panel-shaped, button-shaped, and the like.

[0032] The method for molding the new molded product is not particularly limited, and conventionally known molding methods can be employed. Examples include injection molding, injection compression molding, extrusion molding, shape extrusion, transfer molding, hollow molding, gas-assisted hollow molding, blow molding, extrusion blow molding, IMC (in-mold coating) molding, rotational molding, multilayer molding, two-color molding, insert molding, sandwich molding, foam molding, and pressure molding. In particular, the resin composition of this embodiment is suitable for molded products obtained by injection molding, injection compression molding, and extrusion molding. However, it goes without saying that the resin composition obtained by the manufacturing method of this embodiment is not limited to molded products obtained by these methods.

[0033] The new molded products in this embodiment are preferably used in electrical and electronic equipment / components, office automation equipment / components, information terminal equipment / components, machine parts, home appliances, vehicle parts, building materials, various containers, leisure goods and miscellaneous items, lighting equipment, and the like. [Examples]

[0034] The present invention will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate, as long as they do not depart from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or other reasons, measurements can be taken using other instruments with equivalent performance.

[0035] 1.Raw materials The following ingredients were used. [Table 1]

[0036] <Manufacturing of resin pellets (A1)> With respect to 39.3 parts by mass of polyphenylene ether (A), 0.2 parts by mass of stabilizer (C) and 1.5 parts by mass of mold release agent (D) were mixed, and using a twin-screw extruder (manufactured by Shibaura Machine Co., Ltd.: TEM18SS), melt kneading was carried out at a cylinder temperature of 280 °C and a screw rotation speed of 350 rpm to obtain resin pellets (A1).

[0037] Examples 1 to 3, Comparative Examples 1 and 2, Reference Example 1 <Compound> With respect to 41 parts by mass of the resin pellets (A1) obtained above, 59 parts by mass of polystyrene shown in Table 2 or Table 3 were blended, and using a twin-screw extruder (manufactured by Shibaura Machine Co., Ltd.: TEM18SS), melt kneading was carried out at a cylinder temperature of 280 °C and a screw rotation speed of 350 rpm to obtain resin pellets (B1). The screen meshes of #40 and #100 were used in combination. At this time, as shown in Table 2 or Table 3, the resin pellets (A1) before being charged into the extruder or the resin pellets (B1) were subjected to magnet treatment or metal detector treatment by MRS. In Tables 2 and 3, the descriptions of "1" and "2" for the magnet treatment or metal detector treatment by MRS indicate the order in which the treatments were carried out. For example, Example 1 shows that the resin pellets (A1) were subjected to MRS treatment and the resin pellets (B1) obtained by melt kneading were subjected to metal detector treatment. Also, the MRS treatment was carried out using a product manufactured by Daicatek Co., Ltd., product number: DDR200, magnetic force rating 11000 gauss, with a cut-out amount of 100 kg / h, a belt speed of 0.5 m / s, and a separation plate angle of 80 degrees. The metal detector treatment was carried out using a product manufactured by Zak贺 Technical Research Institute Co., Ltd., product number: MHD1-20, with a supply amount of 5 kg / h and a detection voltage of 600 mV.

[0038] The following evaluations were carried out using the resin pellets (B1) after MRS treatment or metal detector treatment.

[0039] <Manufacture of ISO test pieces> The pellets (B1) obtained by the above manufacturing method were dried at 100°C for 2 hours, and then 4 mm thick ISO3167:93A type test specimens (hereinafter referred to as "ISO test specimens") were injection molded in accordance with ISO-15103 under conditions of cylinder temperature of 280°C and mold temperature of 70°C using an injection molding machine (Shibaura Machine Co., Ltd., "EC75SX").

[0040] <Tensile strength> In accordance with ISO-527, the tensile strength (in MPa) was measured using the ISO test specimens obtained above.

[0041] <Charpy impact strength> The ISO test specimens obtained above were machined in accordance with ISO-179-1 and ISO-179-2 to remove the gripping portions at both ends and to create a notch in the center, thereby forming a notched Charpy impact test specimen. The impact resistance of the obtained notched Charpy impact test specimens was evaluated in accordance with ISO-179-1 and ISO-179-2, measuring the notched Charpy impact strength (unit: kJ / m) at 23°C. 2 ) was measured. Furthermore, the notched Charpy impact strength was measured after heat treatment at 100°C for 100 hours, and its retention rate was determined (notched Charpy impact strength retention rate after heat resistance test).

[0042] <Yield before extrusion, yield after extrusion> Pre-extrusion yield was measured as the percentage of resin pellets (A1) that remained unremoved after magnetic treatment using MRS or metal detection before being fed into the extruder. Post-extrusion yield was measured as the percentage of resin pellets (B1) that remained unremoved after magnetic treatment using MRS or metal detection after being fed into the extruder. In other words, the yield is based on the amount of resin pellets (B1) after being fed into the extruder, and losses due to extrusion are not included in the yield. While magnetic spectroscopy (MRS) can detect and remove only metal-containing pellets, metal detector spectroscopy removes not only metal-containing resin pellets but also non-metal-containing pellets in the surrounding area. In other words, a metal detector for resin pellets will remove not only the resin pellets in which metal is detected, but also the non-metal-containing resin pellets in the area where metal was detected. Therefore, the yield shown here differs from the percentage of pellets remaining after removing only the metal-containing pellets.

[0043] <Resin pressure 50 minutes after the start of extrusion> The above extruder was used with a combination of screen meshes #40 and #100, and the resin pressure (in MPa) was measured 50 minutes after material was introduced. By treating the resin pellets (A1) before extrusion with a magnetic detector using MRS or a metal detector, metal did not clog the screen mesh, and the resin pressure did not rise. In other words, a lower resin pressure indicates better extruder performance. Note that Example 1 does not use a mesh.

[0044] [Table 2]

[0045] [Table 3]

[0046] As is clear from the above results, the method for producing the resin composition of the present invention yielded high yield and excellent extrudeability of the resulting resin pellets (Examples 1-3). In particular, performing metal detection treatment on the resin pellets after extrusion (B1) resulted in a significantly higher yield. Furthermore, performing magnetic treatment with MRS on the resin pellets before extrusion (A1) allowed for the maintenance of a low resin pressure, resulting in even better extrudeability. In contrast, when only metal detection treatment was performed on the resin pellets (A1) before extrusion (Comparative Example 1), the yield was low. Furthermore, when magnetic treatment using MRS was performed after metal detection treatment (Comparative Example 2), the yield was also low. In particular, even if large metal particles are removed by screen meshing, improving apparent impact resistance, fine metal particles that pass through the screen mesh tend to remain, worsening the notched Charpy impact strength after heat resistance testing. However, this problem has been avoided in the present invention.

[0047] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible without departing from the intent and scope of the invention.

Claims

1. A process of obtaining resin pellets (B) by putting a thermoplastic resin material (A) containing metal and other components into an extruder and melt-kneading them, A step of reducing the amount of metal in a thermoplastic resin material (A) or resin pellet (B) containing the aforementioned metal using a magnet, The process includes reducing the amount of metal in a thermoplastic resin material (A) or resin pellet (B) containing the aforementioned metal using a metal detector. A method for manufacturing a resin composition, wherein the step of reducing the amount of metal in the pellets using the metal detector is performed after the step of reducing the amount of metal in the pellets using the magnet.

2. A method for producing a resin composition according to claim 1, wherein the step of reducing the amount of metal in the pellet using the magnet is performed on a thermoplastic resin material (A) containing metal.

3. A method for producing a resin composition according to claim 1, wherein the step of reducing the amount of metal in the pellet using the metal detector is performed on the resin pellet (B).

4. The process of reducing the amount of metal in the pellet using the magnet is performed on a thermoplastic resin material (A) containing metal. A method for producing a resin composition according to claim 1, wherein the step of reducing the amount of metal in the pellet using the metal detector is performed on the resin pellet (B).

5. A method for producing the resin composition according to claim 1, wherein the thermoplastic resin material (A) containing the metal is a resin pellet derived from waste material.

6. A method for producing the resin composition according to claim 1, wherein the thermoplastic resin material (A) containing the metal comprises a magnetic metal and a non-magnetic metal.

7. A method for producing the resin composition according to claim 1, wherein the thermoplastic resin material (A) containing the metal includes a polystyrene resin.

8. The thermoplastic resin material (A) containing the aforementioned metal is a resin pellet derived from waste material. The thermoplastic resin material (A) containing the aforementioned metal includes a magnetic metal and a non-magnetic metal. A method for producing a resin composition according to any one of claims 1 to 4, wherein the thermoplastic resin material (A) containing the metal includes a polystyrene resin.

9. A method for producing a resin composition according to any one of claims 1 to 7, wherein the step of reducing the amount of metal in the pellets using the magnet is performed using a magnet bar and / or a magnet roll separator.

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