Sorting and recovering method and method for producing recycled articles containing polybutylene terephthalate resin

Abstract

To provide a method for sorting and recovering molded articles containing more than 95% by mass of polybutylene terephthalate resin from molded articles containing polybutylene terephthalate resin.SOLUTION: Method for sorting and recovering molded articles containing more than 95% by mass of polybutylene terephthalate resin from molded articles containing polybutylene terephthalate resin, comprises introducing molded articles X containing polybutylene terephthalate resin into liquid A having a density of 1.31 to 1.33 g / cm3 and recovering molded articles Xa floating in liquid A from among the molded articles X introduced into liquid A.SELECTED DRAWING: None

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to a method for sorting and recovering waste and a method for producing recycled materials containing polybutylene terephthalate resin. [Background technology]

[0002] In recent years, recovering and reusing reusable plastics from waste has become an extremely important issue for protecting the global environment. Plastics are primarily made from petroleum, and when incinerated or landfilled as waste, they are prone to causing environmental problems, making recycling increasingly important.

[0003] Among plastic materials, polyethylene terephthalate (PET) resin (hereinafter referred to as "PET resin") is a resin that is generally being collected and separated. PET bottles in particular are produced in large quantities, and because each part is generally made from a single resin, such as polyethylene terephthalate resin for the bottles and polypropylene or polyethylene resin for the caps, separation is easy and recycling costs are relatively low, leading to a high collection rate in Japan.

[0004] Methods for separating plastics include, for example, a spectroscopic method (see, for example, Patent Documents 1 and 2), a wind-based separation method (see, for example, Patent Documents 3 and 4), and a separation method that utilizes the specific gravity of liquids (see, for example, Patent Document 5). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-108526 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-153882 [Patent Document 3] Japanese Patent Application Publication No. 09-193155 [Patent Document 4] Japanese Patent Application Laid-Open No. 2000-288422 [Patent Document 5] Japanese Patent Application Laid-Open No. 2006-326506 Summary of the Invention [Problem to be solved by the invention]

[0006] Among polyester resins, polybutylene terephthalate resin (hereinafter referred to as "PBT resin") crystallizes more easily than PET resin, making it easier to mold. Furthermore, its relatively low melting point among engineering plastics allows it to be combined with a variety of additives. For this reason, PBT resin is used in a wide range of applications, often incorporating inorganic fillers, amorphous resins, flame retardants, and other additives. However, because many molded products containing PBT resin contain various additives, it can be difficult to achieve consistent quality when recycled by melt-blending and re-pelletizing recovered PBT resin-containing molded products. On the other hand, there are also products, such as automotive connectors, monolayer films, and semiconductor carriers, that are made almost entirely of PBT resin. Recovering only these products from the market would facilitate recycling.

[0007] In view of the above, an embodiment of the present invention provides a method for sorting and recovering molded articles containing more than 95% by mass of PBT resin from molded articles containing PBT resin. Another embodiment of the present invention provides a method for producing recycled materials containing PBT resin. [Means for solving the problem]

[0008] The present invention encompasses the following aspects, but is not limited to the following aspects. [1] A method for sorting and recovering molded articles containing more than 95% by mass of polybutylene terephthalate resin from molded articles containing polybutylene terephthalate resin, the method comprising: 3and collecting molded articles Xa floating in the liquid A from among the molded articles X introduced into the liquid A. [2] The method according to [1], wherein the liquid A comprises dichloromethane. [3] Density 1.28~1.29g / cm 3 The method according to [1] or [2], further comprising: introducing the molded article Xa recovered from the liquid A into a liquid B; and recovering molded articles Xb that sink into the liquid B from the molded articles Xa introduced into the liquid B. [4] The method according to [3], wherein the liquid B comprises bromobutane.

[0009] [5] A method for producing a recycled material containing a polybutylene terephthalate resin, comprising measuring the intrinsic viscosity of a molded article sorted and recovered by the method according to any one of [1] to [4], and then performing solid-state polymerization of the molded article. [6] The method for producing a recycled material containing a polybutylene terephthalate resin according to [5], wherein the solid-state polymerization is carried out so that the intrinsic viscosity of the solid-state polymer obtained by the solid-state polymerization is in the range of 0.6 to 1.3 dL / g. [7] A method for producing a recycled material containing the polybutylene terephthalate resin according to [5] or [6], further comprising melt-kneading a raw material containing the solid-state polymer obtained by the solid-state polymerization. [8] A method for producing a recycled material containing a polybutylene terephthalate resin, comprising melt-kneading a raw material containing the molded article sorted and recovered by the method according to any one of [1] to [4]. [9] The method for producing a recycled material containing a polybutylene terephthalate resin according to [7] or [8], wherein the raw material further contains an additive. [Effects of the Invention]

[0010] According to an embodiment of the present invention, a method for sorting and recovering molded articles containing more than 95% by mass of PBT resin from molded articles containing PBT resin can be provided. Also, according to another embodiment of the present invention, a method for producing recycled materials containing PBT resin can be provided. [Brief explanation of the drawings]

[0011] [Figure 1A] FIG. 1A is a flow chart that schematically illustrates steps in an example of a method for producing a recycled material containing a PBT resin according to an embodiment of the present invention. [Figure 1B] FIG. 1B is a flowchart schematically showing the steps of another example of a method for producing a recycled material containing a PBT resin according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

[0013] In an embodiment, a method for sorting and recovering molded articles containing more than 95% by mass of polybutylene terephthalate resin from molded articles containing polybutylene terephthalate resin (hereinafter also referred to as a "sorting and recovery method"), 3 The method includes: introducing a molded article X containing a polybutylene terephthalate resin into the liquid A; and recovering a molded article Xa floating in the liquid A from among the molded articles X introduced into the liquid A.

[0014] In this way, by using a liquid of a predetermined density, it is possible to select and recover molded articles containing more than 95% by mass of PBT resin from molded articles containing PBT resin by a density-based method. This method is also suitable for selecting and recovering molded articles containing more than 95% by mass of PBT resin from recovered products. The PBT resin content of the molded articles to be selected and recovered may be, for example, more than 95% by mass, 99% by mass or more, or 99.5% by mass or more.

[0015] In the embodiment, the separation and recovery method is carried out in a manner that the density is 1.31 to 1.33 g / cm 3 The method includes pouring a molded article X containing a PBT resin into the liquid A, and recovering molded articles Xa floating in the liquid A from among the molded articles X poured into the liquid A (hereinafter also referred to as "step A").

[0016] The method for obtaining the molded article X containing the PBT resin is not particularly limited. A method for sorting out molded articles X containing PBT resin from resin molded articles collected from the market as general industrial waste, etc., includes, for example, a method of sorting by spectroscopic measurement, etc. Examples of the sorting method by spectroscopic measurement include a method of irradiating a sample with near-infrared light and determining the type of resin based on the transmitted light that passes through the sample or the reflected light that is reflected from the sample.

[0017] Furthermore, molded articles containing halogen elements such as bromine and antimony derived from flame retardants may be excluded in advance by fluorescent X-ray analysis or the like.

[0018] Furthermore, some of the resin molded products collected from the market have metal inserts, such as terminals and collars. To reduce contamination factors during sorting using density, molded products with metal inserts may be removed in advance. Molded products with metal inserts can be removed, for example, by using a magnetic material such as a magnet to remove them, or by shredding them in a crusher and then removing them using a magnetic material.

[0019] In step A, the molded article X containing PBT resin may be introduced into liquid A in the form of a molded article. However, for example, if each molded article X is large, the molded article X may be crushed in advance and the crushed molded article X may be introduced into liquid A. A combination of these forms may also be used. The method for crushing the molded article X and the size and shape of the crushed product are not particularly limited. For example, a commercially available crusher may be used to crush the molded article. Crusher manufacturers include Morita Seiki Co., Ltd., Kawata Co., Ltd., and Horai Co., Ltd. If the number of molded articles to be crushed is small, a crusher such as a Wiley crusher may be used.

[0020] The molded articles to be subjected to the sorting and recovery method may be one type or a combination of two or more types. For example, in step A, one or more types of molded articles X may be introduced into liquid A in the form of molded articles or crushed materials.

[0021] Density 1.31~1.33g / cm 3 Examples of Liquid A include dichloromethane, 3-chloro-1,2-propanediol, and isopropyl bromide. For example, one or a combination of two or more of these may be used. From the viewpoint of preventing melting and deterioration of the PBT resin when Liquid A is removed, Liquid A is preferably a liquid with a low boiling point, and from this viewpoint, it preferably contains dichloromethane. For example, Liquid A may contain dichloromethane in an amount of 50% by mass or more, 70% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass, based on the total amount of Liquid A.

[0022] Additives that can be included in molded articles containing PBT resin include, for example, flame retardants, flame retardant aids, inorganic fillers, antioxidants, and lubricants. Examples of flame retardants include bromine-based flame retardants and phosphorus-based flame retardants. Examples of flame retardant aids include nitrogen-based compounds such as melamine cyanurate and antimony oxides. Examples of inorganic fillers include glass fiber, talc, and mica. However, these flame retardants, flame retardant aids, and inorganic fillers generally have a higher density than PBT resin, and molded articles containing these additives generally have a higher density than PBT resin. Furthermore, the amount of antioxidants and lubricants added to molded articles is typically around 1% by mass or less, and their impact on the density of the molded article is usually very small. Furthermore, elastomers and other additives are sometimes added to molded articles to impart impact resistance, and amorphous resins are sometimes added to molded articles to improve dimensional accuracy, but these are often used in combination with inorganic fillers. Therefore, in general, the density of molded products containing PBT resin almost always exceeds the density of PBT resin. Therefore, when the density is 1.31 to 1.33 g / cm 3 In step A using liquid A, a molded article X containing PBT resin is poured into liquid A and the molded article X floating in liquid A is recovered, and it is generally believed that a molded article whose main component is PBT resin can be recovered.

[0023] In process A, molded product X is mixed with a material having a density of 1.31 to 1.33 g / cm 3 The molded article Xa is then poured into liquid A, and the molded article Xa floating in liquid A is recovered. The recovered molded article Xa may be in the form of a molded article, a pulverized product, or a combination thereof, depending on the form of the molded article X poured into liquid A. The molded article X poured into liquid A will float or sink in liquid A depending on its density. In step A, molded articles that do not sink but float in liquid A are recovered. The time from pouring the molded article X into liquid A to recovering the molded article Xa floating in liquid A is preferably 1 to 60 minutes, more preferably 5 to 15 minutes. To speed up the floating and settling, stirring, ultrasonic treatment, centrifugation, or a combination thereof may be performed. This allows molded articles containing inorganic fillers such as glass fibers to be removed more efficiently.

[0024] In step A, there is no particular limitation on the method for recovering the molded article Xa floating in the liquid A. For example, the molded article Xa floating in the liquid A can be recovered using a rotary screen, a screw conveyor, or the like. After collecting the molded product Xa, the liquid A may be reused.

[0025] In the embodiment, the separation and recovery method is carried out in a manner that the density is 1.28 to 1.29 g / cm 3 The method may further include introducing the molded articles Xa recovered from liquid A into liquid B, and recovering molded articles Xb that sink into liquid B from the molded articles Xa introduced into liquid B (hereinafter also referred to as "step B"). In step B, the molded article Xa may be introduced into liquid B in the form of a molded article, or the molded article Xa in the form of a pulverized product may be introduced into liquid B. A combination of these forms is also possible. For example, if the molded article Xa recovered in step A is in the form of a pulverized product, the molded article Xa in the form of a pulverized product may be introduced into liquid B as is.

[0026] As mentioned above, generally, the density of molded products containing PBT resin is higher than that of PBT resin, and it is considered very rare that the density is lower than that of PBT resin. However, even if a component with a lower density than PBT resin, such as an amorphous resin or elastomer, is contained in a molded product without being used in combination with an inorganic filler, it can be separated by using liquid B, which has a lower density than PBT resin, in process B.

[0027] Examples of Liquid B include dichlorotoluene, bromobutane, and dichloroethylene. For example, one or a combination of two or more of these may be used. Liquid B is preferably a liquid with a low boiling point in order to reduce melting and degradation of the PBT resin when Liquid B is removed by drying. From this viewpoint, bromobutane and dichloroethylene (cis-isomer) are preferred. For example, Liquid B may contain one or more selected from the group consisting of bromobutane and dichloroethylene (cis-isomer) in an amount of 50% by mass or more, 70% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass, based on the total amount of Liquid B. For example, Liquid B may contain bromobutane in an amount of 50% by mass or more, 70% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass, based on the total amount of Liquid B.

[0028] In process B, the molded product Xa is mixed with a molten metal having a density of 1.28 to 1.29 g / cm 3 The molded article Xa is then poured into liquid B, and the molded article Xb floating in liquid B is recovered. The recovered molded article Xb may be in the form of a molded article, a pulverized product, or a combination thereof, depending on the form of the molded article Xa poured into liquid B. The time from pouring the molded article Xa into liquid B until the molded article Xb settling in liquid B is recovered is, for example, preferably 1 to 60 minutes, more preferably 5 to 15 minutes. To speed up the floating and settling, stirring, ultrasonic treatment, centrifugation, or a combination thereof may be performed.

[0029] In step B, there is no particular limitation on the method for recovering the molded article Xb that has settled in liquid B. For example, the molded article Xb that has settled in liquid B may be recovered using a screw conveyor, a sludge conveyor, or the like, or after removing floating matter, it may be separated from liquid B using a filter press or the like. After collecting the molded product Xb, the liquid B may be collected and reused.

[0030] In order to remove Liquid A and / or Liquid B from the molded article recovered in Step A or Step B, drying by heating or the like may be carried out. For drying, for example, a dryer or the like may be used. The heating temperature depends on the boiling points of Liquid A and / or Liquid B, but is, for example, preferably 60 to 200°C, more preferably 70 to 150°C. The heating time is, for example, preferably 0.3 to 3 hours, more preferably 0.5 to 1 hour.

[0031] By the above-described method for sorting and recovering, molded articles containing more than 95% by mass of PBT resin can be sorted and recovered in the form of molded articles or pulverized products thereof from molded articles containing PBT resin.

[0032] The molded articles sorted and recovered by the above-described sorting and recovery method can be used to produce recycled materials containing PBT resin. In the above-described sorting and recovery method, molded articles containing more than 95% PBT resin can be sorted and recovered in the form of molded articles or crushed products thereof. In the production of recycled materials containing PBT resin according to the embodiments described below, molded articles in the form of molded articles or crushed products recovered by the sorting and recovery method according to the embodiments can be used as they are, or crushed products obtained by crushing the recovered molded articles can be used. The recycled materials containing PBT resin can be in the form of pellets, for example.

[0033] As described in detail below, the method for producing a recycled material containing a PBT resin according to an embodiment may include measuring the intrinsic viscosity (IV) of the molded article sorted and recovered by the above-described sorting and recovery method, and then performing solid-state polymerization of the molded article. The method for producing a recycled material containing PBT resin according to an embodiment may also include melt-kneading a raw material containing polybutylene terephthalate resin, as described in detail below. The raw material containing polybutylene terephthalate resin used in the melt-kneading may be, for example, a solid-phase polymer obtained by the solid-phase polymerization described above and / or a molded product sorted and recovered by the sorting and recovery method described above, and additives such as an antioxidant and a lubricant may also be added.

[0034] In such a method for producing recycled materials, molded articles containing more than 95% by mass of PBT resin sorted and recovered by the above-mentioned sorting and recovery method are used, so it is possible to produce recycled materials whose main component is PBT resin, for example, recycled materials whose PBT resin content is more than 95% by mass, more preferably 99% by mass, and even more preferably 99.5% by mass or more.

[0035] In the manufacturing method of the recycled material containing PBT resin according to the embodiment, there are no particular limitations on the method for melt-kneading the raw materials. For example, the materials may be fed into an extruder, melt-kneaded, and pelletized. There are no particular limitations on the equipment or conditions of the extruder used, but it is preferable to use a single-screw extruder to prevent deterioration due to melt-kneading. When using a twin-screw extruder, for example, the discharge rate and rotation speed can be reduced, or an element or screw pattern with low kneading capacity can be used. Furthermore, additives such as antioxidants and lubricants may be added as needed during melt-kneading.

[0036] For example, when producing recycled materials for products that require durability, such as automobiles, the intrinsic viscosity (IV) of the molded articles and / or their pulverized material sorted and recovered by the above-mentioned sorting and recovery method may be measured, and solid-state polymerization may be carried out according to the intrinsic viscosity (IV). The intrinsic viscosity (IV) can be measured in o-chlorophenol at a temperature of 35°C.

[0037] The intrinsic viscosity (IV) of PBT resins for use in injection-molded products is preferably 0.6 dL / g or more, and more preferably 0.7 dL / g or more. Furthermore, the intrinsic viscosity (IV) is preferably 1.3 dL / g or less, and more preferably 1.2 dL / g or less. PBT resins having an intrinsic viscosity (IV) within this range are suitable for use in injection-molded products. For example, it is preferable to carry out solid-state polymerization so that the intrinsic viscosity (IV) of the resulting solid-state polymer is in the range of 0.6 to 1.3 dL / g, more preferably 0.7 to 1.2 dL / g.

[0038] The solid-state polymerization conditions can be appropriately adjusted taking into account the target intrinsic viscosity, etc. For example, solid-state polymerization can usually be carried out under reduced pressure or in an inert gas atmosphere. The polymerization temperature may be, for example, 120 to 220°C, preferably 140 to 200°C, and more preferably about 150 to 190°C. The polymerization time is, for example, 1 to 50 hours, more preferably about 3 to 20 hours. These conditions can be appropriately adjusted to obtain the desired intrinsic viscosity. For example, if a PBT resin with an intrinsic viscosity of about 0.80 dL / g is subjected to solid-state polymerization and the intrinsic viscosity is desired to be increased to about 0.90 dL / g, in some cases, the solid-state polymerization may be carried out in a nitrogen atmosphere, for example, at about 170°C for about 15 hours, but the conditions are not limited thereto and can be appropriately adjusted.

[0039] Since molded articles and the like collected from the market may differ in the intrinsic viscosity (IV) and degree of deterioration of the PBT resin originally used, the intrinsic viscosity (IV) can be measured, for example, every 1000 kg, preferably every 500 kg, and more preferably every 100 kg, and then adjusted by solid-state polymerization. Furthermore, when solid-state polymerization is performed in the form of a molded article, the polymerization begins from the surface of the molded article, which may result in variations in the intrinsic viscosity. From the viewpoint of suppressing variations in the intrinsic viscosity, it is preferable to solid-state polymerize a molded article in the form of a pulverized product.

[0040] An example of a method for producing recycled materials according to an embodiment, including an example of a sorting and recovery method according to an embodiment, will be described with reference to the drawings. FIG. 1A is a flowchart outlining the steps of an example of a method for producing a recycled material containing PBT resin according to an embodiment, and FIG. 1B is a flowchart outlining the steps of another example of a method for producing a recycled material containing PBT resin according to an embodiment. Both the method shown in FIG. 1A and the method shown in FIG. 1B involve sorting and recovering molded articles containing more than 95% by mass of PBT resin in the form of pulverized material using an example of the sorting and recovery method according to an embodiment. The sorting and recovery method according to an embodiment and the method for producing a recycled material containing PBT resin according to an embodiment are not limited to the methods shown in FIG. 1A and 1B. For example, while FIGS. 1A and 1B include a solid-state polymerization step (S5) described below, the method for producing a recycled material containing PBT resin according to an embodiment may, but does not necessarily, include steps such as measuring the intrinsic viscosity (IV) of the selected molded articles and solid-state polymerization of the selected molded articles, as needed. In addition, the sorting and recovery method of the embodiment is for a material having a density of 1.31 to 1.33 g / cm 3 It goes without saying that the method may be any method including the steps of: putting a molded article X containing a polybutylene terephthalate resin into liquid A; and recovering molded articles Xa floating in liquid A from the molded articles X put into liquid A (step A).

[0041] In both the method shown in FIG. 1A and the method shown in FIG. 1B, molded articles containing more than 95% by mass of PBT resin are sorted and collected in the form of pulverized material from molded articles collected from the market, and then recycled material containing PBT resin is produced using the pulverized material.

[0042] The method shown in FIG. 1A will be described as an example. In the method shown in FIG. 1A, first, spectroscopic measurement is performed on molded articles collected from the market, and molded articles containing PBT resin are selected and collected. In FIG. 1A, this is shown as a spectroscopic separation step (S1). Next, from the molded articles containing PBT resin selected and collected in the spectroscopic separation step (S1), molded articles with metal inserts are removed, for example, by a method using a magnetic material. In FIG. 1A, this is shown as a magnetic component separation step (S2). Next, the molded articles containing PBT resin are pulverized. In FIG. 1A, this is shown as a pulverization step (S3). Next, the molded articles in the form of pulverized material obtained in the pulverization step (S3) are pulverized to a density of 1.31 to 1.33 g / cm. 3 The molded product Xa is then poured into liquid A, and a pulverized product Xa suspended in liquid A is recovered. In FIG. 1A, this process is designated as step A (SA). The molded product Xa recovered in step A (SA) is then dried. In FIG. 1A, this process is designated as drying step (S4). The pulverized molded product Xa dried in drying step (S4) proceeds to the next step (S5), where the intrinsic viscosity of the molded product Xa is measured, followed by solid-state polymerization. In FIG. 1A, this process is designated as solid-state polymerization step A (S5). After the solid-state polymerization step (S5), the resulting solid-state polymer is melt-kneaded. In FIG. 1A, this process is designated as melt-kneading step (S6). In the method shown in FIG. 1A, a recycled material containing PBT resin is obtained in this manner.

[0043] In the method shown in FIG. 1B, between step A (SA) and the drying step (S4), the pulverized molded product Xa recovered in step A (SA) is dried to a density of 1.28 to 1.29 g / cm. 3 1A except that a step (referred to as step B(SB) in FIG. 1B) of pouring the powder into liquid B and recovering the pulverized molded product Xb that settles in liquid B is performed. In the method shown in FIG. 1B, the pulverized molded product Xb recovered in step B(SB) is dried in a drying step (S4).

[0044] For example, a PBT resin composition may be produced by further adding additives such as a flame retardant, an inorganic filler, an antioxidant, a lubricant, an elastomer, etc. to the recycled material containing PBT resin obtained by the method for producing a recycled material containing PBT resin according to the embodiment, as needed. In this case, for example, the material may be fed into an extruder such as a twin-screw extruder, melt-kneaded, and pelletized. [Example]

[0045] Specific examples are given below, but the present invention is not limited to these examples.

[0046] Test pieces 1 to 10 were prepared as follows using the materials shown in Table 1. The amount of additive listed in Table 1 is the ratio (mass %) to the total amount of resin and additive. The test piece materials listed in Table 1 were melt-mixed and extruded using a 30 mm diameter twin-screw extruder (TEX-30 manufactured by The Japan Steel Works, Ltd.) at the following cylinder temperature and screw rotation speed of 130 rpm to obtain pellets for preparing each test piece. The cylinder temperature was 250°C for the pellets used for test pieces 1 to 7, which were made of polybutylene terephthalate resin; 260°C for the pellets used for test piece 8, which were made of polyamide resin; 320°C for the pellets used for test piece 9, which were made of polyphenylene sulfide resin; and 200°C for the pellets used for test piece 10, which were made of polyacetal resin. These pellets were dried at 140°C for 3 hours for test pieces 1 to 7, 100°C for 8 hours (vacuum drying) for test piece 8, 140°C for 3 hours for test piece 9, and 80°C for test piece 10 for 4 hours. Then, they were injection molded at the following cylinder and mold temperatures to prepare Type 1A tensile test pieces (test pieces 1 to 10) conforming to ISO 3167. The cylinder temperatures were 250°C for test pieces 1 to 7, 260°C for test piece 8, 320°C for test piece 9, and 200°C for test piece 10. The mold temperatures were 80°C for test pieces 1 to 7, 80°C for test piece 8, 140°C for test piece 9, and 80°C for test piece 10. Table 1 also shows the density of each test piece obtained. The following process was carried out using the obtained test pieces to prepare recycled materials.

[0047] [Table 1]

[0048] The IR of each test piece was measured by the attenuated total reflection (ATR) method using a Fourier infrared spectrophotometer "FT-IR NICOLET iS5" (product name) manufactured by Thermo Fisher Scientific, and only test pieces containing polybutylene terephthalate resin were selected.

[0049] A 12,000 gauss bar magnet was applied to the selected tensile test specimens to confirm that they did not stick to each other.

[0050] Thereafter, the selected test pieces were crushed in a Willey crusher to obtain crushed products.

[0051] The obtained pulverized material was placed in a 500 ml beaker containing 300 ml of dichloromethane, and the mixture was stirred. After 10 minutes, the floating pulverized material was collected.

[0052] The ground material recovered from the above treatment using dichloromethane was added to a 500 ml beaker containing 300 ml of bromobutane, and the mixture was stirred. After 10 minutes, the settled ground material was recovered.

[0053] The pulverized material recovered from the above treatment using bromobutane was placed in a dryer at 120°C and dried for 1 hour.

[0054] The intrinsic viscosity of the dried pulverized product was measured using an Ubbelohde viscometer in o-chlorophenol at a temperature of 35° C. The intrinsic viscosity was 0.68 dL / g.

[0055] The dried pulverized product was subjected to solid-state polymerization at 160° C. for 10 hours in a nitrogen atmosphere. After the intrinsic polymerization, the intrinsic viscosity of the resulting polymer was measured and found to be 0.73 dL / g.

[0056] To 100 parts by mass of the polymer obtained by the above solid-state polymerization, 0.4 parts by mass of "Irganox 1010" (trade name) manufactured by BASF Japan Ltd. was added as an antioxidant, and the mixture was melt-kneaded at 250°C using a twin-screw extruder ("PCM-30" (trade name) manufactured by Ikegai Corporation) and pelletized using a cutter.

[0057] The melting point of the resulting pellets was measured using a Yanaco Technical Science micromelting point analyzer "MP-100X" (trade name), and was found to be 224°C. This melting point, along with the fact that test pieces containing polybutylene terephthalate resin were selected by IR analysis, indicates that the resulting pellets primarily contain polybutylene terephthalate resin. Furthermore, 1 g of the resulting pellets was placed in a crucible and heated in an electric furnace at 600°C for 3 hours. The residue was then measured and found to be 0.0002 g, confirming that the pellets were PBT resin pellets containing almost no inorganic matter. [Explanation of symbols]

[0058] S1 Spectroscopic separation process S2 Magnetic component separation process S3 Crushing process SA process A SB Engineering B S4 Drying Project S5 Solid Phase Recognition Engineering S6 Melt Mixing Process

Claims

1. A method for sorting and recovering molded articles containing more than 95% by mass of polybutylene terephthalate resin from molded articles containing polybutylene terephthalate resin, comprising: ３ and collecting molded articles Xa floating in the liquid A from the molded articles X introduced into the liquid A.

2. The method of claim 1 , wherein Liquid A comprises dichloromethane.

3. A method for producing a recycled material containing polybutylene terephthalate resin, comprising measuring the intrinsic viscosity of the molded article sorted and recovered by the method of claim 1, and then performing solid-state polymerization of the molded article.

4. The method for producing a recycled material containing polybutylene terephthalate resin according to claim 3, wherein the solid-state polymerization is carried out so that the intrinsic viscosity of the solid-state polymer obtained by the solid-state polymerization is in the range of 0.6 to 1.3 dL / g.

5. The method for producing a recycled material containing the polybutylene terephthalate resin according to claim 3, further comprising melt-kneading a raw material containing the solid-state polymer obtained by the solid-state polymerization.

6. A method for producing a recycled material containing polybutylene terephthalate resin, comprising melt-kneading a raw material containing the molded articles sorted and recovered by the method of claim 1.

7. The method for producing a recycled material containing polybutylene terephthalate resin according to claim 5 or 6, wherein the raw material further contains an additive.

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