Method for recycling thermoplastic resin molded article, resin particle, method for producing the same, and electronic component

Abstract

To provide a method for recycling a thermoplastic resin molding capable of recycling the thermoplastic resin molding in such a state that metallic foreign matter mixed in a state of adhering to a pulverized product is little when the thermoplastic resin molding is recycled as a thermoplastic resin or a thermoplastic resin composition.SOLUTION: The method for recycling a thermoplastic resin or a thermoplastic resin composition as a constituent material of a thermoplastic resin molded product includes a step of grinding the thermoplastic resin molded product in a temperature range of (A) or (B) below by a grinder. (A) when the thermoplastic resin is a resin other than a cyclic olefin resin, (Ambient temperature at which elastic modulus of the thermoplastic resin is reduced by half) - 15°C. or higher, and (melting point of the thermoplastic resin) - 10°C, or lower. (B) when the thermoplastic resin is a cyclic olefin resin, (glass transition temperature (Tg) of the cyclic olefin resin) - 15°C. or higher and (flow starting temperature of the cyclic olefin resin) - 10°C, or lower.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for recycling thermoplastic resin molded articles, resin particles and a method for producing the same, and electronic parts. [Background technology]

[0002] In recent years, there has been growing interest in recycling in order to protect the global environment. In particular, with regard to the recycling of plastic molded products (thermoplastic resin molded products), the raw materials for which are finite resources such as petroleum, if plastic waste could be recycled, it would be useful from both a resource conservation and economic perspective, and various technological developments are being promoted.

[0003] One example of plastic recycling is material recycling, in which waste plastic is crushed, processed into pellets, and reused as raw material for plastic (see Patent Document 1). Waste plastic includes not only plastic that has been used as a product and then disposed of, but also plastic that is discarded without being used as a product, such as sprues and runners in injection molding. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-72796 Summary of the Invention [Problem to be solved by the invention]

[0005] When recycling plastics, if the molded products, which are waste plastics, are crushed, and the molded products have a high hardness above a certain level, friction and other factors are increased in the crusher, which can result in the inclusion of metal powder as impurities. Furthermore, when air is blown through pipes, the resin passing through the pipes can abrade the inner walls of the pipes, resulting in the inclusion of metal powder. Metallic foreign matter such as metal powder is usually removed using a metal checker (magnet) or by sieving. For example, metal wear powder from pipes can be removed using a metal checker (magnet).

[0006] However, the inventors discovered that metallic foreign matter may be mixed in not only as metal powder but also in a state where it is attached to the pulverized material. In this case, if the size of the pulverized material to which the metallic foreign matter is attached is larger than the mesh size of the sieve, it will remain and cannot be removed even by sieving. Furthermore, if the metallic foreign matter is simply metal powder, it can be removed with a metal checker (magnet). However, if the metallic foreign matter is mixed in in a state where it is attached to the pulverized material, it cannot be attracted by a magnet depending on the weight of the pulverized material and the position of the metallic foreign matter, and therefore cannot be removed.

[0007] As mentioned above, if metal is mixed into the crushed material, the quality of the resulting recycled product will be unstable, and if the amount of metal foreign matter is large, it may not be usable as a recycled product. For example, if the recycled product is used in electronic parts such as connectors, the mixed metal may cause a decrease in insulation or heat generation, impairing the product's functionality. When a load is applied to the molded product, stress may concentrate in the areas where foreign matter (metal powder) is present, becoming the starting point of fracture and preventing the product from achieving its original strength.

[0008] The present invention has been made in consideration of the above-mentioned conventional problems, and an object of the present invention is to provide a method for recycling thermoplastic resin molded articles that can be recycled by reducing the amount of metallic foreign matter that gets mixed in and adheres to the pulverized material when the thermoplastic resin molded article is recycled as a thermoplastic resin or a thermoplastic resin composition. Another object of the present invention is to provide resin particles with reduced metallic foreign matter contamination, a method for producing the same, and an electronic component. [Means for solving the problem]

[0009] In response to the new problem of metallic foreign matter adhering to the pulverized material and being mixed in, which cannot be removed by conventional methods, the inventors have identified the mechanism by which metallic foreign matter is mixed in when adhering to the pulverized material, and have found a method for suppressing metal adhesion to the pulverized material. That is, the inventors have discovered that, while the amount of metallic foreign matter adhering to the pulverized material increases when the temperature of the molded product to be pulverized is low, the amount of metallic foreign matter adhering to the pulverized material can be reduced when the molded product to be pulverized is pulverized when the temperature of the molded product to be pulverized is high, and have completed the present invention. One aspect of the present invention that solves the above problem is as follows.

[0010] (1) A method for recycling a thermoplastic resin or a thermoplastic resin composition that is a constituent material of a thermoplastic resin molded product, comprising: A method for recycling a thermoplastic resin molded article, comprising the step of crushing the thermoplastic resin molded article by a crusher at a temperature within the following temperature range (A) or (B): (A) When the thermoplastic resin is other than a cyclic olefin resin, the temperature range is from −15° C. or higher, which is the environmental temperature at which the elastic modulus of the thermoplastic resin at room temperature is reduced by half, to −10° C. or lower, which is the melting point of the thermoplastic resin. (B) When the thermoplastic resin is a cyclic olefin resin, the temperature range is the glass transition temperature (Tg) of the cyclic olefin resin minus 15°C or more and the flow initiation temperature of the cyclic olefin resin minus 10°C or less.

[0011] (2) The method for recycling thermoplastic resin molded products according to (1), wherein the crusher is a crusher that crushes the thermoplastic resin molded products by the rotation of a rotary blade arranged on a rotating member, and the linear velocity of the tip of the rotary blade is 64π m / min or more.

[0012] (3) A method for recycling thermoplastic resin molded products according to (1) or (2), wherein the crusher is a crusher that crushes the thermoplastic resin molded products by rotating a rotary blade arranged on a rotating member, and has a clearance of 0.25 mm or more between the rotary blade and a member other than the rotary blade.

[0013] (4) The method for recycling a thermoplastic resin molded article according to any one of (1) to (3), wherein the temperature range of (A) or (B) is maintained in the step.

[0014] (5) The method for recycling a thermoplastic resin molded article according to any one of (1) to (4) above, wherein the thermoplastic resin composition contains a filler.

[0015] (6) The method for recycling a thermoplastic resin molded product according to any one of (1) to (5), wherein the thermoplastic resin is one selected from the group consisting of polyarylene sulfide resin, liquid crystalline resin, polyacetal resin, polybutylene terephthalate resin, cyclic olefin resin, polyaryl ether ketone resin, polypropylene resin, and polyamide resin.

[0016] (7) The method for recycling a thermoplastic resin molded product according to any one of (1) to (5), wherein the thermoplastic resin is one selected from the group consisting of polyarylene sulfide resin, liquid crystalline resin, polyacetal resin, polybutylene terephthalate resin, cyclic olefin resin, and polyaryl ether ketone resin.

[0017] (8) The method for recycling a thermoplastic resin molded product according to (7), wherein, when the thermoplastic resin is one of the following thermoplastic resins, the temperature range of the thermoplastic resin molded product in the step is set to the following temperature range. Polyarylene sulfide resin: 105°C or higher, temperature range of polyarylene sulfide resin melting point -10°C or lower Liquid crystal resin: 105°C or higher, temperature range of the liquid crystal resin melting point -10°C or lower Polyacetal resin: Temperature range of 60°C or higher, or 10°C below the melting point of polyacetal resin Polybutylene terephthalate resin: -75°C or higher, temperature range below the melting point of polybutylene terephthalate resin -10°C Cyclic olefin resin: Temperature range above the glass transition temperature (Tg) of cyclic olefin resin and below the flow initiation temperature of cyclic olefin resin -10°C Polyaryletherketone resin: 145°C or higher, or the melting point of polyaryletherketone resin -10°C or lower

[0018] (9) A method for producing resin particles in which resin particles containing reduced metal foreign matter are obtained by pulverizing a resin molded product in a temperature range of the following (A) or (B): A method for producing resin particles, wherein when 5 kg of resin particles obtained by crushing at a temperature within the range of (A) or (B) below are inspected with a metal detection device that satisfies the conditions below, the number of times an induced electromotive force of 1000 mV or more is detected is 50% or less of the number of times it is detected when 5 kg of resin particles crushed at room temperature are inspected. (A) When the thermoplastic resin is other than a cyclic olefin resin, the temperature range is from −15° C. or higher, which is the environmental temperature at which the elastic modulus of the thermoplastic resin at room temperature is reduced by half, to −10° C. or lower, which is the melting point of the thermoplastic resin. (B) When the thermoplastic resin is a cyclic olefin resin, the temperature range is the glass transition temperature (Tg) of the cyclic olefin resin minus 15°C or more and the flow initiation temperature of the cyclic olefin resin minus 10°C or less. [Conditions for metal detection equipment] A metal detection device in which a detection coil is arranged radially outward of a cylinder made of a non-magnetic material, and when a high-frequency current is applied to the detection coil to cause it to oscillate, resin particles poured from a hopper fall due to gravity and pass through the internal space of the cylinder, and which can detect the induced electromotive force generated when metal foreign matter attached to the resin particles passes through the internal space.

[0019] (10) The method for producing resin particles according to (9) above, wherein the metal foreign matter contains iron.

[0020] (11) Resin particles obtained by crushing a resin molded product and having reduced metal foreign matter contamination, Resin particles in which the metal foreign matter is substantially present in a state of adhering to the surface of the resin particles, [solid bulk density of the resin particles / density of the resin composition constituting the resin particles] x 100 is 46.0% or more, and when 5 kg of the resin particles are inspected using a metal detection device that satisfies the following conditions, an induced electromotive force of 1000 mV or more is detected 80 or less times. [Conditions for metal detection equipment] A metal detection device in which a detection coil is arranged radially outward of a cylinder made of a non-magnetic material, and when a high-frequency current is applied to the detection coil to cause it to oscillate, resin particles poured from a hopper fall due to gravity and pass through the internal space of the cylinder, and which can detect the induced electromotive force generated when metal foreign matter attached to the resin particles passes through the internal space.

[0021] (12) Resin particles obtained by crushing a resin molded product and having reduced metal foreign matter contamination, The metal foreign matter is present substantially in a state of adhering to the surface of the resin particle, and [specific surface area calculated assuming all of the resin particles are true spheres of the average particle diameter / BET specific surface area of ​​the resin particle] × 100 × (100 / (100 - average particle diameter (mm)))) is 60% or more, and when 5 kg of the resin particles are inspected using a metal detection device that satisfies the following conditions, an induced electromotive force of 1000 mV or more is detected 80 or less times. [Conditions for metal detection equipment] A metal detection device in which a detection coil is arranged radially outward of a cylinder made of a non-magnetic material, and when a high-frequency current is applied to the detection coil to cause it to oscillate, resin particles poured from a hopper fall due to gravity and pass through the internal space of the cylinder, and which can detect the induced electromotive force generated when metal foreign matter attached to the resin particles passes through the internal space.

[0022] (13) The resin particles according to (11) or (12), wherein the metal foreign matter contains iron.

[0023] (14) An electronic component having reduced contamination with metallic foreign matter, which is formed by molding the resin particles according to (11) or (12). [Effects of the Invention]

[0024] According to the present invention, a method for recycling a thermoplastic resin molded article can be provided, which allows the thermoplastic resin molded article to be recycled as a thermoplastic resin or a thermoplastic resin composition with a low content of metal foreign matter. Furthermore, according to the present invention, it is possible to provide resin particles with reduced contamination of metallic foreign matter, a method for producing the same, and an electronic component. DETAILED DESCRIPTION OF THE INVENTION

[0025] <Recycling methods for thermoplastic resins> The method for recycling a thermoplastic resin according to the present embodiment (hereinafter also simply referred to as the "recycling method according to the present embodiment") is a method for recycling a thermoplastic resin or a thermoplastic resin composition that is a constituent material of a thermoplastic resin molded product, and is characterized by including a step of pulverizing the thermoplastic resin molded product by a pulverizer in the temperature range of the following (A) or (B): (A) If the thermoplastic resin is other than a cyclic olefin resin, the temperature range is from -15°C or higher, where the elastic modulus of the thermoplastic resin at room temperature is reduced by half, to -10°C or lower, where the melting point of the thermoplastic resin is (B) When the thermoplastic resin is a cyclic olefin resin, the temperature range is the glass transition temperature (Tg) of the cyclic olefin resin minus 15°C or more and the flow initiation temperature of the cyclic olefin resin minus 10°C or less.

[0026] Here, the term "tip of the blade" in this specification refers to the part of the rotary blade that is involved in crushing between the rotary blade and the fixed blade. Furthermore, the "rotary blade" in this specification is not necessarily a thin, sharp member. Furthermore, the term "rotary blade" as used herein refers to a member that rotates at a linear velocity of 64π m / min or more and crushes an object by pinching it between two rotary blades or between a rotary blade and a fixed blade. The rotary blade may be a rotating member having multiple small blades. Furthermore, although the term "fixed" blade is used herein for convenience, it does not necessarily refer to a blade that is completely stationary, but may also refer to blades that rotate in the same direction but at different speeds, or may rotate in different directions. Also, a "fixed blade" is not necessarily a thin, sharp member. The rotating direction of the rotary blade and fixed blade need not only be parallel to each other, but they may also rotate when combined at an angle, such as in the case of an inclined blade or a bevel gear. Rotating at a linear velocity of 64π m / min or more does not only mean that the rotating blade alone rotates at 64π m / min or more, but also means that when the fixed blade is rotating, if one blade is considered to be stationary (fixed blade), the other blade (rotating blade) has a relative linear velocity of 64π m / min or more due to the relationship between the rotation direction, speed difference, etc.

[0027] In this embodiment, when a thermoplastic resin molded product (hereinafter simply referred to as a "molded product") is crushed, the molded product is kept at a predetermined temperature range, thereby reducing the inclusion of metallic foreign matter. The estimated mechanism is shown below, but the actual mechanism of metallic foreign matter contamination is not necessarily as described below. When a molded product rotating in contact with the rotating member and / or rotary blade comes into contact with a component inside the crusher (excluding the rotating blade and fixed blade), the "component inside the crusher" is scraped, and the scraped component adheres to and becomes mixed into the rotating molded product. For example, a crushed material may be sandwiched between the side of the rotating member perpendicular to the rotation axis of the rotor and the inner wall surface of the crusher body, and as the crushed material rotates, the side of the rotating member or the inner wall surface of the crusher body is scraped by the crushed material, resulting in the crushed material adhering to and becoming mixed in. Another example is a crushed material sandwiched between the rotating blade and a screen (mesh), and as the crushed material rotates, the screen (mesh) is scraped by the crushed material, resulting in the crushed material adhering to and becoming mixed in. In either case, the object sandwiched is not limited to a crushed material, but may also be a molded product. The reason why the components inside the crusher are scraped as described above is thought to be that the molded product has a high hardness above a certain level at room temperature. In this embodiment, by setting the temperature within a predetermined range when crushing the molded article, the molded article is softened, and the amount of metal powder that rubs against the inner wall and peels off and becomes free can be reduced. Therefore, in the recycling method of this embodiment, it is possible to recycle thermoplastic resin molded articles with a low content of metallic foreign matter. The recycling method of this embodiment will be described in detail below. The constituent material of the thermoplastic resin molded product may be a thermoplastic resin or a thermoplastic resin composition. A thermoplastic resin composition is a thermoplastic resin blended with an additive such as a filler. In the following description, unless otherwise specified, the term "thermoplastic resin" may also include a thermoplastic resin composition.

[0028] In the recycling method of this embodiment, as described above, when a thermoplastic resin molded product is pulverized, the temperature is set to a predetermined range (the above (A) or (B)) depending on whether the thermoplastic resin is a cyclic olefin resin. For example, a thermoplastic resin molded product at a temperature lower than the predetermined temperature range may be heated to the predetermined temperature range. Alternatively, parts other than the product obtained during injection molding (e.g., runners, sprues, etc.) or defective products generated during the manufacturing process of a molded product may be introduced into a pulverizer after molding while the temperature of the molded product is still within the predetermined temperature range (before it cools below the predetermined temperature range). In the above (A), the thermoplastic resin is other than a cyclic olefin resin, and the temperature range is set based on the ambient temperature and melting point at which the elastic modulus at room temperature of the thermoplastic resin constituting the thermoplastic resin molded product to be pulverized is reduced by half. Therefore, in order to implement the recycling method of this embodiment, it is necessary to identify the thermoplastic resin constituting the thermoplastic resin molded product and to know the ambient temperature and melting point at which the elastic modulus at room temperature of the thermoplastic resin is reduced by half. That is, before pulverizing a thermoplastic resin molded product, the thermoplastic resin constituting the thermoplastic resin molded product is identified, and the ambient temperature at which the elastic modulus of the thermoplastic resin at room temperature is halved and its melting point are determined. The ambient temperature at which the elastic modulus of the thermoplastic resin at room temperature is halved can be determined, for example, from the temperature dependence of the elastic modulus obtained by dynamic mechanical analysis (DMA) of the thermoplastic resin. It can also be determined from the temperature dependence of the elastic modulus obtained by tensile testing or bending testing using a universal testing machine. The melting point can be a temperature generally known as the melting point of the thermoplastic resin. Then, during pulverization, the temperature is set to a range from −15°C or higher (the ambient temperature at which the elastic modulus of the thermoplastic resin constituting the thermoplastic resin molded product to be pulverized) to −10°C or lower (the melting point of the thermoplastic resin). From the viewpoint of sufficiently softening the thermoplastic resin, the temperature range is preferably above the ambient temperature at which the elastic modulus of the thermoplastic resin at room temperature is halved and below −20°C or lower (the melting point of the thermoplastic resin), and more preferably above +15°C or higher (the ambient temperature at which the elastic modulus of the thermoplastic resin at room temperature is halved) to −30°C or lower (the melting point of the thermoplastic resin). On the other hand, in the case of (B) above, when the thermoplastic resin is a cyclic olefin resin, the predetermined temperature range for crushing the thermoplastic resin molded article is set based on the glass transition temperature (Tg) and flow initiation temperature of the cyclic olefin resin. Therefore, when implementing the recycling method of this embodiment, if the specified thermoplastic resin is a cyclic olefin resin, it is necessary to know the glass transition temperature (Tg) and flow initiation temperature of the cyclic olefin resin. That is, if the specified thermoplastic resin is a cyclic olefin resin, the glass transition temperature (Tg) and flow initiation temperature of the cyclic olefin resin are determined before crushing the thermoplastic resin molded article. The glass transition temperature (Tg) can be a temperature commonly known as the glass transition temperature (Tg) of thermoplastic resins. The flow initiation temperature can be measured using a melt viscosity measuring device capable of measuring temperature rise, such as a high-temperature flow tester.

[0029] If the thermoplastic resin constituting the thermoplastic resin molded product is unknown, it can be identified by known methods, such as infrared spectroscopy, gas chromatography mass spectrometry (GC / MS), or NMR measurement, where appropriate, to identify the thermoplastic resin.

[0030] The crusher is not particularly limited, and various types can be used. However, the true value of the recycling method of this embodiment is demonstrated by a crusher equipped with a crushing container that accommodates the thermoplastic resin molded article to be crushed and a rotating member that achieves crushing by rotating within the crushing container. More specifically, it is a crusher that crushes the thermoplastic resin molded article by rotating a rotary blade disposed on the rotating member. This is because, in such a crusher, friction occurs between the molded article and the rotary blade and the inner wall of the crushing container during crushing, which is expected to cause the metal on the inner wall to rub and become loose. However, in the recycling method of this embodiment, the molded article and its fragments soften during crushing, reducing friction with the inner wall of the crushing container and preventing the metal on the inner wall from becoming loose as metal powder. Examples of the crusher include high-speed rotary crushers such as hammer mills and pin mills, roll crushers, cutter mills, and the like. The material of the rotary blade of the crusher is not particularly limited, and examples include those made of various metals, but common examples include alloy steels such as high-speed steel, die steel, molybdenum steel, and tungsten steel, and those containing iron such as carbon steel. The material of the inner wall of the crusher is not particularly limited, and examples thereof include various metals. Common examples include alloy steels such as high-speed steel, die steel, molybdenum steel, and tungsten steel, and iron-containing materials such as carbon steel. As described above, the foreign metal matter that may be mixed in by crushing a molded product originates from components (rotary blades, inner walls, etc.) inside the crusher, and therefore the foreign metal matter includes the material of the components inside the crusher. Therefore, for example, if at least one of the rotating blades and inner walls of the crusher is made of a material containing iron, such as alloy steel or carbon steel, the foreign metal matter will contain iron, and more specifically, will include a metal component derived from at least one of alloy steel and carbon steel. The proportion of iron in the foreign metal matter varies depending on the material of the components inside the crusher, but for example, if the components inside the crusher are made of general alloy steel or carbon steel, it will usually be in the range of 80 to 100 mass%.

[0031] On the other hand, in the recycling method of this embodiment, the effect is more pronounced when the crusher is a crusher that crushes thermoplastic resin molded articles by rotating a rotary blade arranged on a rotating member, as described above, and the linear velocity of the tip of the rotary blade is 64π m / min or greater. In high-speed crushers with a linear velocity of the tip of the rotary blade of 64π m / min or greater, the clearance between the rotary blade and components other than the rotary blade—for example, the clearance between the rotary blade and the side of the crusher body itself perpendicular to the rotation axis of the rotor, or the clearance between the rotary blade and the screen (mesh)—tends to be larger than in crushers with a linear velocity of less than 64π m / min. For example, this clearance may be 0.25 mm or greater, or 0.30 mm or greater. When such clearance is large and the rotary blade rotates at high speed, the molded articles rotating in contact with the rotating member and / or the rotary blade come into contact with components inside the crusher (excluding the rotary blade and fixed blade), which can easily shave off these "components inside the crusher." In the recycling method of this embodiment, the molded article is softened by maintaining the temperature within a predetermined range (above (A) or (B)) during crushing, thereby reducing friction between the molded article and the components inside the crusher and preventing metal from being liberated from the components inside the crusher. Therefore, the recycling method of this embodiment is particularly effective when using a high-speed crusher with a linear velocity of the tip of the rotary blade of 64π m / min or more. Furthermore, high-speed crushers with a linear velocity of the tip of the rotary blade of 64π m / min or more have the advantage of having high processing capacity and being able to recycle a large number of thermoplastic resin molded articles in a short period of time. In consideration of crushing processing capacity, the linear velocity of the tip of the rotary blade in such a high-speed crusher is preferably 68π m / min or more, and more preferably 73π m / min or more. The upper limit of the linear velocity of the tip of the rotary blade is generally 150π m / min. When a molded product is crushed using a crusher with a linear velocity of the tip of the rotary blade of 64π m / min or more at a temperature below the ambient temperature of −15°C, at which the elastic modulus of the thermoplastic resin constituting the thermoplastic resin molded product at room temperature is reduced by half, the molded product does not soften and rubs against the inner wall of the crushing container, causing the metal constituting the inner wall to become liberated as metal powder and mix with the resin (see Comparative Example 1 described below).

[0032] In the recycling method of this embodiment, it is preferable to maintain the temperature range of (A) or (B) in the step of crushing the thermoplastic resin molded article using a crusher. If the temperature drops during crushing and the molded article and its fragments harden, there is a risk of metal foreign matter being mixed in, as described above. Therefore, if the temperature falls below the lower limit of the above temperature range during crushing, it is preferable to heat the molded article to within the above temperature range.

[0033] In particular, when the thermoplastic resin composition used as a constituent material of the thermoplastic resin molded product contains a filler, it is preferable to set the temperature during pulverization within the temperature range (A) or (B). When the thermoplastic resin composition contains a filler, the filler may rub against the inner wall of the pulverizing container, liberating the metal on the inner wall as metal powder, which may result in more metal foreign matter being mixed in than when the thermoplastic resin composition does not contain a filler. Therefore, when the thermoplastic resin composition used as a constituent material of the thermoplastic resin molded product contains a filler, it is even more important that the molded product softens during pulverization than when the thermoplastic resin composition does not contain a filler. The filler is not particularly limited, but examples thereof include organic or inorganic fillers such as fibrous fillers, granular fillers, and plate-like fillers.

[0034] In the recycling method of this embodiment, the thermoplastic resin that is the constituent material of the thermoplastic resin molded product may be, for example, one selected from the group consisting of polyarylene sulfide resin, liquid crystal resin, polyacetal resin, polybutylene terephthalate resin, cyclic olefin resin, polyaryl ether ketone resin, polypropylene resin, and polyamide resin. Among them, one selected from the group consisting of polyarylene sulfide resin, liquid crystal resin, polyacetal resin, polybutylene terephthalate resin, cyclic olefin resin, and polyaryl ether ketone resin is preferred.

[0035] Typical environmental temperatures at which the elastic modulus of a thermoplastic resin is reduced to half of its room temperature are listed below. Polyarylene sulfide resin: 120℃ Liquid crystal resin: 120℃ Polyacetal resin: 75℃ Polybutylene terephthalate resin: 90℃ Polyaryletherketone resin: 160℃

[0036] The melting points of the above thermoplastic resins are listed below. However, since cyclic olefin resins do not have a melting point, the flow initiation temperature is listed. Polyarylene sulfide resin: 280-290°C Liquid crystal resin: 280 to 370°C Polyacetal resin: 165 to 180°C Polybutylene terephthalate resin: 220 to 228°C Cyclic olefin resin: 170-260°C (flow temperature) Polyaryletherketone resin: 370℃ Polypropylene resin: 160℃ Polyamide resin: 225 to 265°C

[0037] In the recycling method of this embodiment, when the thermoplastic resin constituting the thermoplastic resin molded product is one of the above-mentioned thermoplastic resins, it is crushed by a crusher at a predetermined temperature range for each. The temperature range to be set during crushing for each thermoplastic resin constituting the thermoplastic resin molded product is shown below. Polyarylene sulfide resin: 105°C or higher, temperature range of polyarylene sulfide resin melting point -10°C or lower Liquid crystal resin: 105°C or higher, temperature range of the liquid crystal resin melting point -10°C or lower Polyacetal resin: Temperature range of 60°C or higher, or 10°C below the melting point of polyacetal resin Polybutylene terephthalate resin: 75°C or higher, temperature range of polybutylene terephthalate resin melting point -10°C or lower Cyclic olefin resin: Temperature range of cyclic olefin resin glass transition temperature -15°C or higher, and cyclic olefin resin flow initiation temperature -10°C or lower Polyaryletherketone resin: 145°C or higher, or the melting point of polyaryletherketone resin -10°C or lower

[0038] In the recycling method of this embodiment, the thermoplastic resin molded product is pulverized as described above to reduce the content of metallic foreign matter. The product can then be removed from the pulverizer in granular or powder form and stored. Alternatively, the product can be remolded as is, or it can be mixed with new (virgin) material of the same thermoplastic resin and molded. Furthermore, if the pulverized material obtained as described above is mixed with various raw materials to repelletize or maintain physical properties and compounded, the amount of metallic foreign matter mixed in can be reduced, thereby reducing damage to the extruder.

[0039] There are no particular restrictions on the size of the pulverized thermoplastic resin molded product, but it is preferably 2 to 10 mm, more preferably 2.5 to 9 mm, and particularly preferably 3 to 8 mm.

[0040] <Resin particles and their manufacturing method> The method for producing resin particles of this embodiment is a method for producing resin particles in which resin particles with reduced metal foreign matter contamination are obtained by crushing a resin molded product at a predetermined temperature range, and is carried out under conditions such that when 5 kg of resin particles obtained by crushing at a temperature range of (A) or (B) below are inspected with a metal detection device that meets the following conditions, with the metal foreign matter substantially present and attached to the surface of the resin particles, the number of times an induced electromotive force of 1000 mV or more is detected is 50% or less of the number of times it is detected when 5 kg of resin particles crushed at room temperature are inspected. (A) When the thermoplastic resin is other than a cyclic olefin resin, the temperature range is from −15° C. or higher, which is the environmental temperature at which the elastic modulus of the thermoplastic resin at room temperature is reduced by half, to −10° C. or lower, which is the melting point of the thermoplastic resin. (B) When the thermoplastic resin is a cyclic olefin resin, the temperature range is the glass transition temperature (Tg) of the cyclic olefin resin minus 15°C or more and the flow initiation temperature of the cyclic olefin resin minus 10°C or less. [Conditions for metal detection equipment] A metal detection device in which a detection coil is arranged radially outward of a cylinder made of a non-magnetic material, and when a high-frequency current is applied to the detection coil to cause it to oscillate, resin particles poured from a hopper fall due to gravity and pass through the internal space of the cylinder, and which can detect the induced electromotive force generated when metal foreign matter attached to the resin particles passes through the internal space. As such a metal detection device, for example, the metal detection devices described in JP-A-2011-237278, JP-A-2016-145804, JP-A-2018-025552, JP-A-2018-091787, JP-A-2018-118196, etc. can be used. More specifically, Metallidar manufactured by Saika Technical Research Institute, a general incorporated foundation, can be used as a commercially available product. In the method for producing resin particles according to the present embodiment, it is not necessary for the metallic foreign matter to be present only in a state of being substantially attached to the surface of the resin particles, and a step for satisfying this requirement, such as a step of removing metallic particles not attached to the resin particles by sieving or the like, may be carried out before the above-described inspection is carried out.

[0041] In the method for producing resin particles according to this embodiment, a resin molded product is pulverized within a predetermined temperature range. By setting the temperature range, the amount of metallic foreign matter contaminating the resin particles is reduced. This temperature range is set so that, when 5 kg of resin particles obtained by pulverization within the temperature range (A) or (B) described above are inspected with a metal detector under the same conditions, the number of detections of an induced electromotive force of 1000 mV or greater is 50% or less of the number of detections when 5 kg of resin particles pulverized at room temperature are inspected. When inspected with a metal detector under the same conditions, the detection of an induced electromotive force of 1000 mV or greater indicates that metallic foreign matter has passed through the internal space of the metal detector. A low number of detections of an induced electromotive force of 1000 mV or greater indicates that fewer metallic foreign matter has passed through. Therefore, in this embodiment, a temperature range is identified in which the number of detections of an induced electromotive force of 1000 mV or greater is 50% or less of the number of detections of an induced electromotive force of 1000 mV or greater for resin particles pulverized at room temperature is obtained. By pulverizing the resin particles within this temperature range, resin particles with reduced metallic foreign matter can be obtained. In this embodiment, it is assumed that the metallic foreign matter is present in a state where it is substantially attached to the surface of the resin particles when the above inspection is carried out.

[0042] As described above in the recycling method of this embodiment, the temperature range is set to the temperature range (A) or (B) specified for each thermoplastic resin. Therefore, by setting the temperature range as described above, resin particles with a low content of metallic foreign matter can be obtained.

[0043] In this embodiment, the number of times an induced electromotive force of 1000 mV or more is detected is used as an indicator of the reduction in the inclusion of metal foreign matter. However, since the degree of insulation required for molded products made from resin particles varies depending on the application, and the detection sensitivity can be affected by the particle size of the resin particles, the appropriate induced electromotive force threshold can be changed as appropriate by a person skilled in the art, and the technical concept of the manufacturing method of this embodiment is included in the number of times the induced electromotive force is detected, determined in this manner, when the number of times the induced electromotive force is detected is 50% or less when crushed in the above temperature range compared to when crushed at room temperature.

[0044] On the other hand, the resin particles of this embodiment, in a first form, are resin particles obtained by pulverizing a resin molded product and having reduced contamination with metal foreign matter, and the metal foreign matter is essentially present in a state of adhering to the surface of the resin particles, and [solid bulk density of resin particles / density of resin composition constituting the resin particles] x 100 is 46.0% or more, and when 5 kg of resin particles are inspected using a metal detection device that meets the following conditions, an induced electromotive force of 1000 mV or more is detected 80 or less times. In addition, in a second form, the resin particles of this embodiment are resin particles in which the inclusion of metallic foreign matter obtained by pulverizing a resin molded product has been reduced, and the metallic foreign matter is substantially present in a state of adhering to the surface of the resin particles, and [specific surface area of ​​calculated value assuming all resin particles are true spheres of average particle diameter / BET specific surface area of ​​resin particles] × 100 × particle diameter correction is 60% or more, and when 5 kg of resin particles are inspected with a metal detection device that meets the following conditions, the number of times an induced electromotive force of 1000 mV or more is detected is 80 or less.

[0045] Both the first and second types of resin particles of this embodiment can be produced by the resin particle manufacturing method of this embodiment described above. Therefore, the inclusion of metallic foreign matter is reduced. The resin particles of the first type have a [bulk density of resin particles / density of resin composition constituting the resin particles] × 100 of 46.0% or more, which specifies the shape of the resin particles. Specifically, this indicates that the resin particles have little shape variation and a low aspect ratio. In contrast, resin particles pulverized without satisfying the temperature conditions specified in the resin particle manufacturing method of this embodiment have shape variation and a high aspect ratio. On the other hand, for the resin particles of the second form, [specific surface area calculated assuming all resin particles are true spheres of the average particle diameter / BET specific surface area of ​​resin particles] × 100 × particle size correction is 60% or more, which specifies the surface condition of the resin particles. Specifically, it indicates that the resin particles have a relatively smooth surface. In contrast, resin particles crushed without satisfying the temperature conditions specified in the resin particle manufacturing method of this embodiment have a rough surface. The smaller the particle diameter, the higher the specific surface area. Therefore, to correct for this, the particle size correction is "(100 / (100 - average particle diameter (mm)))".

[0046] <Electronic components> The electronic component of this embodiment is an electronic component formed from the resin particles of this embodiment described above, and has reduced metallic foreign matter contamination. As described above, the resin particles of this embodiment have reduced metallic foreign matter contamination. Therefore, the electronic component of this embodiment formed from these resin particles also has reduced metallic foreign matter contamination. Therefore, deterioration of insulation and heat generation caused by the mixed metallic foreign matter are suppressed, and deterioration of product functionality can be prevented. Furthermore, if metallic foreign matter is present in an electronic component, when a load is applied to the electronic component, stress concentration occurs at the location where the metallic foreign matter is present, which can become the starting point of damage. However, the electronic component of this embodiment can suppress such damage.

[0047] Specific examples of the electronic component of this embodiment include a relay, a switch, a connector, an actuator, a sensor, a transformer bobbin, a terminal block, a bus bar, a cover, a socket, a coil, and a plug. [Example]

[0048] The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to the following examples.

[0049] [Example 1] First, as a molded product of polyphenylene sulfide resin, "DURAFIDE (registered trademark) 1140A1 (Natural color)" (containing 40% glass fiber by mass, non-fiber-reinforced PPS resin has a melting point of 278°C and a density of 1.66 g / cm3), which is a glass fiber-reinforced polyphenylene sulfide resin (PPS resin) composition manufactured by Polyplastics Co., Ltd. 3 ) was used in an injection molding machine (Sumitomo SE100D) with a mold temperature set at 140°C and a cylinder temperature of 320°C. The molded products were prepared while they were still hot during molding, and the temperature of the molded products was 190°C (88°C below the melting point of PPS resin (278°C)).

[0050] The prepared molded product at 190°C was placed in a crusher (Horai Corporation, V210, rotary blade diameter: 160 mm, clearance between the rotary blade and the side of the crusher body itself perpendicular to the rotation axis of the rotor: 0.30 mm). Next, the molded product was crushed by rotating the rotary blade (rotating member) of the crusher so that the linear velocity of its tip was 75.7π m / min, and a crushed product was obtained. The crushed product was resin particles of 2 to 8 mm. The compacted bulk density of the crushed product was 0.776 g / cm. 3 That is, [solid bulk density of pulverized material / density of resin composition constituting the pulverized material]×100 was 46.7%.

[0051] [Counting the number of metal foreign objects] For 5 kg of the obtained pulverized material, a metal checker (SAIKA, Metallidar MHD15) was used to count the number of times an induced electromotive force of 1000 mV or more was detected, which was taken as the number of metallic foreign matter in the pulverized material. In reality, an induced electromotive force was observed in the range of 1000 to 10239 mV. The counting results are shown in Table 1. Furthermore, when the resin particles sampled (rejected and diverted) during detection by the metal checker were visually inspected, black foreign matter was confirmed. This black foreign matter, normal resin particles not diverted by the metal checker, and the molded product before crushing were analyzed using FT-IR and XRF. FT-IR showed the same spectrum for all. Meanwhile, XRF confirmed a significant increase in iron (Fe) content only in the black foreign matter compared to the normal resin particles and the molded product before crushing. Nearly identical spectra were obtained for all other components. These analysis results indicate that the resin particles (black foreign matter) diverted by the metal checker are metallic foreign matter, including iron, that has adhered to crushed molded product.

[0052] [Comparative Example 1] The molded product was crushed in the same manner as in Example 1, except that the temperature of the molded product when it was fed into the crusher was 25°C (room temperature). The compacted bulk density of the crushed product obtained was 0.756 g / cm 3 That is, [solid bulk density of pulverized material / density of resin composition constituting pulverized material] x 100 was 45.5%. Next, the number of metallic foreign matter particles in the obtained pulverized material was counted in the same manner as in Example 1. The counting results are shown in Table 1.

[0053] [Table 1]

[0054] From Table 1, it can be seen that Example 1, in which the molded article was brought to a predetermined temperature during pulverization, had a smaller number of metallic foreign matter particles than Comparative Example 1, in which the molded article was pulverized at room temperature. This demonstrates that the recycling method of this embodiment can recycle thermoplastic resin molded articles with a low content of metallic foreign matter.

Claims

1. A method for recycling a thermoplastic resin or a thermoplastic resin composition that is a constituent material of a thermoplastic resin molded product, comprising: A method for recycling a thermoplastic resin molded article, comprising the step of pulverizing the thermoplastic resin molded article by a pulverizer at a temperature within the following (A) or (B): (A) When the thermoplastic resin is other than a cyclic olefin resin, the temperature range is from −15° C. to the environmental temperature at which the elastic modulus of the thermoplastic resin at room temperature is reduced by half, to −10° C. to the melting point of the thermoplastic resin. (B) When the thermoplastic resin is a cyclic olefin resin, the temperature range is the glass transition temperature (Tg) of the cyclic olefin resin minus 15°C or more and the flow initiation temperature of the cyclic olefin resin minus 10°C or less.

2. 2. The method for recycling thermoplastic resin molded products according to claim 1, wherein the crusher is a crusher that crushes the thermoplastic resin molded products by rotation of a rotary blade arranged on a rotating member, and the linear velocity of the tip of the rotary blade is 64π m / min or more.

3. 2. The method for recycling thermoplastic resin molded products according to claim 1, wherein the crusher is a crusher that crushes the thermoplastic resin molded products by rotating a rotary blade arranged on a rotating member, and has a clearance of 0.25 mm or more between the rotary blade and a member other than the rotary blade.

4. The method for recycling a thermoplastic resin molded product according to any one of claims 1 to 3, wherein the temperature range of (A) or (B) is maintained in the step.

5. The method for recycling a thermoplastic resin molded article according to any one of claims 1 to 3, wherein the thermoplastic resin composition contains a filler.

6. The thermoplastic resin is one selected from the group consisting of polyarylene sulfide resin, liquid crystal resin, polyacetal resin, polybutylene terephthalate resin, cyclic olefin resin, polyaryl ether ketone resin, polypropylene resin, and polyamide resin. The recycling method for thermoplastic resin molded products according to any one of claims 1 to 3.

7. The thermoplastic resin is one selected from the group consisting of polyarylene sulfide resin, liquid crystal resin, polyacetal resin, polybutylene terephthalate resin, cyclic olefin resin, and polyaryl ether ketone resin. The recycling method for thermoplastic resin molded products according to any one of claims 1 to 3.

8. 8. The method for recycling a thermoplastic resin molded product according to claim 7, wherein, when the thermoplastic resin is one of the following thermoplastic resins, the temperature range of the thermoplastic resin molded product in the step is set to the following temperature range. Polyarylene sulfide resin: 105°C or higher, temperature range of the melting point of polyarylene sulfide resin minus 10°C or lower Liquid crystalline resin: 105°C or higher, melting point of liquid crystalline resin -10°C or lower Polyacetal resin: Temperature range of 60°C or higher, or 10°C below the melting point of polyacetal resin Polybutylene terephthalate resin: -75°C or higher, melting point of polybutylene terephthalate resin -10°C or lower temperature range Cyclic olefin resin: temperature range of the glass transition temperature (Tg) of the cyclic olefin resin or higher and the flow initiation temperature of the cyclic olefin resin minus 10°C or lower Polyaryletherketone resin: temperature range of 145°C or higher, or the melting point of the polyaryletherketone resin minus 10°C or lower

9. A method for producing resin particles, comprising pulverizing a resin molded product at a temperature within the following range (A) or (B) to obtain resin particles having reduced metallic foreign matter contamination, A method for producing resin particles, wherein when 5 kg of resin particles obtained by pulverizing the resin particles in a temperature range of (A) or (B) below are inspected with a metal detection device that satisfies the following conditions, the number of times an induced electromotive force of 1000 mV or more is detected is 50% or less of the number of times it is detected when 5 kg of resin particles pulverized at room temperature are inspected. (A) When the thermoplastic resin is other than a cyclic olefin resin, the temperature range is from −15° C. to the environmental temperature at which the elastic modulus of the thermoplastic resin at room temperature is reduced by half, to −10° C. to the melting point of the thermoplastic resin. (B) When the thermoplastic resin is a cyclic olefin resin, the temperature range is the glass transition temperature (Tg) of the cyclic olefin resin minus 15°C or more and the flow initiation temperature of the cyclic olefin resin minus 10°C or less. [Conditions for metal detection device] A metal detection device in which a detection coil is arranged radially outward of a cylinder made of a non-magnetic material, and when a high-frequency current is applied to the detection coil to cause it to oscillate, resin particles poured from a hopper fall due to gravity and pass through the internal space of the cylinder, and which can detect the induced electromotive force generated when metal foreign matter attached to the resin particles passes through the internal space.

10. The method for producing resin particles according to claim 9 , wherein the metallic foreign matter contains iron.

11. Resin particles obtained by pulverizing a resin molded product and having reduced metal foreign matter contamination, Resin particles in which the metal foreign matter is present substantially in a state of adhering to the surface of the resin particles, [solid bulk density of the resin particles / density of the resin composition constituting the resin particles] x 100 is 46.0% or more, and when 5 kg of resin particles are inspected using a metal detection device that satisfies the following conditions, an induced electromotive force of 1000 mV or more is detected 80 or less times. [Conditions for metal detection device] A metal detection device in which a detection coil is arranged radially outward of a cylinder made of a non-magnetic material, and when a high-frequency current is applied to the detection coil to cause it to oscillate, resin particles poured from a hopper fall due to gravity and pass through the internal space of the cylinder, and which can detect the induced electromotive force generated when metal foreign matter attached to the resin particles passes through the internal space.

12. Resin particles obtained by pulverizing a resin molded product and having reduced metal foreign matter contamination, The metal foreign matter is present substantially in a state of adhering to the surface of the resin particle, and [specific surface area calculated assuming all of the resin particles to be true spheres of the average particle diameter / BET specific surface area of ​​the resin particle] x 100 x (100 / (100-average particle diameter (mm)))) is 60% or more, and when 5 kg of the resin particles are inspected using a metal detection device that satisfies the following conditions, an induced electromotive force of 1000 mV or more is detected 80 or less times. [Conditions for metal detection device] A metal detection device in which a detection coil is arranged radially outward of a cylinder made of a non-magnetic material, and when a high-frequency current is applied to the detection coil to cause it to oscillate, resin particles poured from a hopper fall due to gravity and pass through the internal space of the cylinder, and which can detect the induced electromotive force generated when metal foreign matter attached to the resin particles passes through the internal space.

13. The resin particles according to claim 11 or 12, wherein the metallic foreign matter contains iron.

14. An electronic component having reduced contamination of metallic foreign matter, produced by molding the resin particles according to claim 11 or 12.

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