Structure, structure manufacturing method, and millimeter wave radar module

Abstract

Provided are: a structure obtained by joining two resin members, wherein at least one among the resin members is a resin member having a high electromagnetic wave absorption rate; a structure manufacturing method; and a millimeter wave radar module. This structure has a first member formed of a thermoplastic resin composition A and a second member formed of a thermoplastic resin composition B, wherein: the first member and the second member are at least partially joined; the transmittance of a test piece, obtained by molding the thermoplastic resin composition A so as to have a thickness of 2 mm, at a frequency of 76.5 GHz is at least 70.0%; the transmittance of a test piece, obtained by molding the thermoplastic resin composition B so as to have a thickness of 2 mm, at a frequency of 76.5 GHz is less than 50.0%; and the absorption rate of the test piece, obtained by molding the thermoplastic resin composition B so as to have a thickness of 2 mm, at a frequency of 76.5 GHz is at least 40.0%.

Description

Structure, method for manufacturing structure, and millimeter-wave radar module

[0001] The present invention relates to a structure, a method for manufacturing the structure, and a millimeter-wave radar module, and more particularly to a structure in which a first member and a second member are joined.

[0002] Thermoplastic resins, including polybutylene terephthalate resin, are widely used in various equipment components because they have excellent mechanical strength, chemical resistance, electrical insulation, and other properties, as well as excellent heat resistance, moldability, and recyclability.

[0003] Recently, welding processes have been increasingly used to improve productivity, and laser welding, which has little effect on electronic components, has been widely used. For example, Patent Document 1 discloses a laser-welded product using two molded bodies (members) made of polybutylene terephthalate resin.

[0004] International Publication No. 2017 / 146196

[0005] Here, structures formed by bonding two resin members, such as laser-welded bodies, are also expected to be applied to millimeter-wave radar. Millimeter-wave radar transmits millimeter-wave radio waves with wavelengths of 1 to 10 mm at frequencies of 30 to 300 GHz, particularly 60 to 90 GHz, and detects the presence of obstacles, as well as the distance and relative speed of the object, by receiving reflected waves that collide with the object and return. Recently, such millimeter-wave radar has been affected by noise, not only from transmitted electromagnetic waves but also from reflected electromagnetic waves, which can cause malfunctions. Therefore, there is an increasing demand for structures with high electromagnetic wave absorption and low transmittance and reflectance. The present invention aims to solve this problem by providing a structure formed by bonding two resin members, at least one of which is a resin member with high electromagnetic wave absorption, a method for manufacturing such a structure, and a millimeter-wave radar module.

[0006] In light of the above-mentioned problems, the present inventors have conducted research and found that the above-mentioned problems can be solved by joining a resin member having high electromagnetic wave transmittance with a resin member having low electromagnetic wave transmittance. Specifically, the above-mentioned problems have been solved by the following means. <1> A structure comprising a first member formed from a thermoplastic resin composition A and a second member formed from a thermoplastic resin composition B, wherein the first member and the second member are at least partially joined, and wherein a test piece obtained by molding the thermoplastic resin composition A to a thickness of 2 mm at a frequency of 76.5 GHz has a transmittance calculated according to formula (C) of 70.0% or more, a test piece obtained by molding the thermoplastic resin composition B to a thickness of 2 mm has a transmittance calculated according to formula (C) of less than 50.0% at a frequency of 76.5 GHz, and an absorptance calculated according to formula (A) of 40.0% or more at a frequency of 76.5 GHz. Formula (C) (In the above formula (C), T represents the transmission attenuation measured by the free space method.) Formula (A) (In the above formula (A), R represents the return loss measured by the free space method, and T represents the transmission loss measured by the free space method.) <2> The structure according to <1>, wherein the thermoplastic resin composition B contains a conductive carbon compound. <3> The structure according to <2>, wherein the conductive carbon compound contains carbon nanotubes. <4> The structure according to any one of <1> to <3>, wherein the thermoplastic resin composition B contains a reinforcing material. <5> The structure according to any one of <1> to <4>, wherein the thermoplastic resin composition B contains a polybutylene terephthalate resin. <6> The structure according to any one of <1> to <5>, wherein the thermoplastic resin composition A contains a polybutylene terephthalate resin. <7> The structure according to any one of <1> to <6>, wherein the first member and the second member are joined by any one of laser welding, vibration welding, ultrasonic welding, two-color molding, insert molding, screwing, bonding with an adhesive, and fitting. <8> The structure according to any one of <1> to <6>, wherein the first member and the second member are joined by laser welding, and the first member is on the laser transmission side during laser welding. <9> The structure according to any one of <1> to <8>, wherein the difference between the absorptance at a frequency of 76.5 GHz of a test piece obtained by molding the thermoplastic resin composition A to a thickness of 2 mm, as calculated according to formula (A), and the absorptance at a frequency of 76.5 GHz of a test piece obtained by molding the thermoplastic resin composition B to a thickness of 2 mm, as calculated according to formula (A), is 40.0% or more. <10> The structure according to any one of <1> to <9>, including an electromagnetic wave control element. <11> The structure according to any one of <1> to <10>, wherein the structure has a housing having a hollow structure surrounded by at least the first member and the second member, and the housing contains an element. <12> The structure according to <11>, wherein the element is an element that transmits and / or detects electromagnetic waves, and at least one type of the electromagnetic waves is transmitted through the first member and at least one type of the electromagnetic waves is absorbed by the second member. <13> The structure according to <12>, wherein a first member or a second member is present in both directions opposite to the direction in which the electromagnetic waves are transmitted and / or detected.<14> A method for producing a structure, comprising at least partially joining a first member formed from thermoplastic resin composition A and a second member formed from thermoplastic resin composition B, wherein a test piece obtained by molding the thermoplastic resin composition A to a thickness of 2 mm has a transmittance of 70.0% or more at a frequency of 76.5 GHz, as calculated according to formula (C), a test piece obtained by molding the thermoplastic resin composition B to a thickness of 2 mm has a transmittance of less than 50.0% at a frequency of 76.5 GHz, as calculated according to formula (C), and a test piece obtained by molding the thermoplastic resin composition B to a thickness of 2 mm has an absorptance of 40.0% or more at a frequency of 76.5 GHz, as calculated according to formula (A). (In the above formula (C), T represents the transmission attenuation measured by the free space method.) Formula (A) (In the above formula (A), R represents the return loss measured by the free space method, and T represents the transmission loss measured by the free space method.) <15> A millimeter-wave radar module having the structure described in any one of <1> to <13>.

[0007] The present invention makes it possible to provide a structure in which two resin members are joined together, at least one of which is a resin member with a high electromagnetic wave absorption rate, a method for manufacturing the structure, and a millimeter-wave radar module.

[0008] FIG. 1 is an example of a schematic diagram of a structure of this embodiment; FIG. 2 is an example of a variation of the schematic diagram of a structure of this embodiment; FIG. 3 is an example of a variation of the schematic diagram of a structure of this embodiment; FIG. 4 is an example of a variation of the schematic diagram of a structure of this embodiment; FIG. 5 is an example of a variation of the schematic diagram of a structure of this embodiment; FIG. 6 is a schematic diagram showing a test piece for measuring laser weld strength in the examples; FIG. 7 is a schematic diagram showing a test piece for measuring laser weld strength in the examples; FIG. 8 is a schematic diagram showing a method for measuring laser weld strength in the examples; FIG. 9 is a schematic diagram showing a dumbbell-shaped test piece produced in Example 11;

[0009] Hereinafter, a detailed description will be given of an embodiment of the present invention (hereinafter simply referred to as "the present embodiment"). Note that the following present embodiment is an example for explaining the present invention, and the present invention is not limited to this embodiment. In this specification, the term "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits. In this specification, various physical property values ​​and characteristic values ​​are those at 23°C unless otherwise specified. In this specification, weight average molecular weight and number average molecular weight are polystyrene-equivalent values ​​measured by GPC (gel permeation chromatography). If the measurement method, etc., of the specifications shown in this specification differ depending on the year, they shall be based on the specifications as of January 1, 2021, unless otherwise specified. In this specification, the unit of reflection loss and transmission loss is "dB" (decibels).

[0010] The molded article of this embodiment has a first member formed from thermoplastic resin composition A and a second member formed from thermoplastic resin composition B, with the first member and the second member being at least partially bonded. A test piece molded from the thermoplastic resin composition A to a thickness of 2 mm has a transmittance of 70.0% or more at a frequency of 76.5 GHz as calculated according to formula (C), a test piece molded from the thermoplastic resin composition B to a thickness of 2 mm has a transmittance of less than 50.0% at a frequency of 76.5 GHz as calculated according to formula (C), and a test piece molded from the thermoplastic resin composition B to a thickness of 2 mm has an absorption of 40.0% or more at a frequency of 76.5 GHz as calculated according to formula (A). This configuration provides a structure in which at least one of the resin members is a resin member with high electromagnetic wave absorption. Furthermore, a structure in which at least one of the resin members is a resin member with high electromagnetic wave transmittance can be obtained. That is, the structure of this embodiment can include an electromagnetic wave control body. Such an electromagnetic wave control body is composed of, for example, a first member and a second member, and may further include a third member. Also, such an electromagnetic wave control body may include, for example, a plurality of further members in addition to the third member. Formula (C) (In the above formula (C), T represents the transmission attenuation measured by the free space method.) Formula (A) (In the above formula (A), R represents the return loss measured by the free space method, and T represents the transmission loss measured by the free space method.)

[0011] In this specification, unless otherwise specified, the transmittance refers to the transmittance obtained according to formula (C) at a frequency of 76.5 GHz for a test piece molded to a thickness of 2 mm (preferably, 100 mm x 100 mm x 2 mm). In this specification, unless otherwise specified, the absorbance refers to the absorbance obtained according to formula (A) at a frequency of 76.5 GHz for a test piece molded to a thickness of 2 mm (preferably, 100 mm x 100 mm x 2 mm). In this specification, unless otherwise specified, the reflectance refers to the reflectance obtained according to formula (B) at a frequency of 76.5 GHz for a test piece molded to a thickness of 2 mm (preferably, 100 mm x 100 mm x 2 mm). (In the above formula (B), R represents the return loss measured by the free space method.)

[0012] FIG. 1 is a schematic diagram of an example of a structure according to this embodiment, where (a) shows the structure as viewed from the outside and (b) shows a cross-sectional view. In the embodiment shown in FIG. 1 , 1 denotes a first member formed from thermoplastic resin composition A, and 2 denotes a second member formed from thermoplastic resin composition B. In this embodiment, a test piece molded to a thickness of 2 mm from thermoplastic resin composition A has a transmittance of 70.0% or more, a test piece molded to a thickness of 2 mm from thermoplastic resin composition B has a transmittance of less than 50.0%, and a test piece molded to a thickness of 2 mm from thermoplastic resin composition B has an absorption rate of 40.0% or more. This configuration allows electromagnetic noise to be suppressed by the second member 2 formed from thermoplastic resin composition B. The structure according to this embodiment is preferably a molded article having a hollow structure, and an element 3 (e.g., an element susceptible to electromagnetic wave noise or an element prone to generating electromagnetic wave noise, such as a detection unit of a millimeter-wave radar) is preferably housed inside the hollow structure.

[0013] Specifically, the structure of this embodiment preferably includes a hollow housing surrounded by at least the first member 1 and the second member 2, and the housing contains an element 3, as illustrated in FIG. 1 . The housing in the first embodiment may also be a housing surrounded by the first member, the second member, and a third member. Here, the first member functions as an electromagnetic wave transmitting member that transmits electromagnetic waves, and the second member functions as an electromagnetic wave absorbing member that absorbs electromagnetic waves. The structure also preferably includes an element that transmits and / or detects electromagnetic waves, and at least one type of the electromagnetic waves is transmitted through the first member and absorbed by the second member. This configuration allows the first member and / or the second member to be positioned opposite the surface from which the electromagnetic waves are emitted in the element that transmits and / or detects electromagnetic waves, making it possible to control the direction of irradiation of the laser electromagnetic waves. Furthermore, it is preferable that the first member and / or the second member are present in both directions facing the direction of transmission and / or detection of the electromagnetic waves. This configuration allows the electromagnetic waves to pass through only in some directions, while suppressing or absorbing the reflection of the electromagnetic waves that may cause noise or malfunction in other directions. An example of an embodiment in which the first member and the second member are present in both directions facing the direction of transmission and / or detection of the electromagnetic waves is shown in FIG. 3, which will be described later.

[0014] A specific example of the encapsulated element is an element containing an electromagnetic wave-emitting electronic substrate for millimeter-wave radar. Furthermore, by forming a structure having a surface facing an electromagnetic wave-transmitting member (first member) that transmits the electromagnetic waves emitted from the element and a surface facing an electromagnetic wave-absorbing member (second member) that absorbs the electromagnetic waves emitted from the element, it becomes possible to precisely control the direction of laser electromagnetic wave irradiation. Note that the electromagnetic wave-transmitting member (first member) in this embodiment does not necessarily mean that it transmits 100% of electromagnetic waves, but rather it may be a member formed from thermoplastic resin composition A, i.e., a resin composition having a transmittance of 70.0% or more at a frequency of 76.5 GHz, as calculated according to formula (C) for a test piece molded to a thickness of 2 mm. The electromagnetic wave-absorbing member (second member) in this embodiment does not necessarily mean that it absorbs 100% of electromagnetic waves, but rather it may be a member formed from thermoplastic resin composition B. That is, any component formed from a resin composition in which a test piece molded to a thickness of 2 mm has a transmittance, as calculated according to formula (C), of less than 50.0% at a frequency of 76.5 GHz, and in which a test piece molded to a thickness of 2 mm has an absorptance, as calculated according to formula (A), of 40.0% or more at a frequency of 76.5 GHz, is sufficient.

[0015] The structure of this embodiment is preferably used for radar applications. Specifically, it is used for housings, covers, millimeter-wave radar components, and the like for millimeter-wave radar. In particular, in this embodiment, the structure of this embodiment is preferably used as a millimeter-wave radar module. Examples of millimeter-wave radar modules include automotive millimeter-wave radars used in automatic brake control devices, inter-vehicle distance control devices, pedestrian accident reduction steering devices, erroneous transmission suppression control devices, pedal misapplication acceleration suppression devices, approaching vehicle warning devices, lane keeping assist devices, rear-end collision prevention warning devices, parking assist devices, and vehicle periphery obstacle warning devices; railway and aviation millimeter-wave radars used in platform monitoring / railroad crossing obstacle detection devices, in-train content transmission devices, tram / railway collision prevention devices, and runway foreign object detection devices; millimeter-wave radars for transportation infrastructure such as intersection monitoring devices and elevator monitoring devices; millimeter-wave radars for various security devices; millimeter-wave radars for medical and nursing care applications such as child and elderly monitoring systems; and millimeter-wave radars for transmitting various information content.

[0016] FIG. 2 is an example of a variation of the schematic diagram of the structure of this embodiment, and the same reference numerals are used as in FIG. 1 and a cross-sectional view is shown as in FIG. 1(b). In the structure shown in FIG. 2(a), the first member 1 has a curved surface. That is, in the structure of this embodiment, the first member 1 does not necessarily have to be flat, and its shape can be freely determined. Also, in the structure shown in FIG. 2(a), the first member 1 has the same thickness everywhere when viewed from the cross section, but the thickness of the first member 1 may vary depending on the position. In the structure shown in FIG. 2(a), there is a space between the first member 1 and the element 3, but this space may contain other members. Also, in the structure shown in FIG. 2(a), a portion of the element 3 is not covered by either the first member 1 or the second member 2. That is, in the direction of the element 3 where control of electromagnetic wave absorption or transmission is not required, there is little need to provide the first member 1 or the second member 2. In this case, a third member (not shown) may be further provided to cover the element 3. Also, as shown in Fig. 2(b), the second member 2 may be a structure having a curved surface.

[0017] FIG. 3 is an example of a variation of the schematic diagram of the structure of this embodiment, and the reference numerals are the same as those in FIG. 1 , and the cross-sectional view is the same as that in FIG. 1( b). In the structures shown in FIGS. 3( a) and 3( b), the element 3 is entirely covered by the first member 1 and the second member 2. That is, the first member 1 and the second member 2 form the housing of the element 3. In the structure shown in FIG. 3( a), the second member 2 surrounds the element 3 so that it is in contact with the majority of the element 3. This configuration allows for more effective control of the absorption and transmission of electromagnetic waves. Furthermore, since the second member 2 and the element 3 are in contact with each other over most of the element 3, noise due to reflection of electromagnetic waves emitted from the element 3 can be reduced. Alternatively, as in the structure shown in FIG. 3( b), the first member 1 may surround the element 3 so that it is in contact with the majority of the element 3.

[0018] The structure shown in FIG. 4 is an example of a variation of the schematic diagram of the structure of this embodiment, and shows a front view of the structure. While the reference numerals are the same as those in FIG. 1 , FIG. 4 is a plan view. In the structures shown in FIGS. 4( a) and 4(b), a flat plate-shaped first member 1 and a flat plate-shaped second member 2 are in contact with each other. However, in the structure shown in FIG. 4(a), the portion where the first member 1 and the second member 2 are in contact is relatively short, while in the structure shown in FIG. 4(b), the portion where the first member 1 and the second member 2 are in contact is relatively long. Because the structures shown in FIGS. 4(a) and 4(b) are flat, they are not hollow structures, such as housings containing elements. The structures shown in FIGS. 4(a) and 4(b) are used as sheets to be provided when it is desired to partially transmit electromagnetic waves. Although the structures shown in FIGS. 4(a) and 4(b) are flat, the shape can be appropriately determined depending on the application. For example, the structures may be curved or wave-shaped instead of flat. Furthermore, the thickness does not need to be constant.

[0019] The structure shown in FIG. 5 is an example of a variation of the schematic diagram of the structure of this embodiment, and shows a front view of the structure. The reference numerals are the same as those in FIG. 1 . Like the structure shown in FIG. 4 , the structure shown in FIG. 5 is not a hollow structure, but rather, like the structure shown in FIG. 4 , is a plate-like structure used as a sheet or the like to be provided when it is desired to partially transmit electromagnetic waves. The structure shown in FIG. 5( a) is a structure in which a second member is provided within a first member. In this manner, by providing an electromagnetic wave transmission member (first member) and an electromagnetic wave absorption member (second member), it is possible to transmit electromagnetic waves in desired locations and absorb electromagnetic waves in other desired locations. Furthermore, in the structure shown in FIG. 5( a), the second member is provided within the first member, but as shown in FIG. 5( b), a first member 1 may be provided within a second member 2. Furthermore, multiple second members 2 may be provided within the first member 1. Furthermore, the shapes of the first member 1 and the second member 2 can be appropriately determined depending on the application.

[0020] <Thermoplastic resin composition A> Thermoplastic resin composition A is a resin composition containing a thermoplastic resin, and a test piece molded to a thickness of 2 mm has a transmittance of 70.0% or more at a frequency of 76.5 GHz as determined according to formula (C). By using thermoplastic resin composition A with such a high transmittance, attenuation of the emitted radar is small, making it possible to improve radar sensitivity.

[0021] The transmittance is 70.0% or more, but may be 80.0% or more, and the upper limit is 100.0% or less, but 99.0% or less is practical. By increasing the transmittance, when laser welding is performed with the strength of electromagnetic waves used for radar detection, the laser welding strength can be increased.

[0022] In this embodiment, the absorbance at a frequency of 76.5 GHz of a test piece molded to a thickness of 2 mm from thermoplastic resin composition A, as determined according to formula (A), is preferably 50.0% or less. The absorbance is 40.0% or less, preferably 30.0% or less, more preferably 20.0% or less, even more preferably 15.0% or less, even more preferably 10.0% or less, and even more preferably 8.0% or less. Although a lower limit of 0% is ideal, a value of 0.5% or more will sufficiently satisfy the required performance.

[0023] In this embodiment, the reflectance at a frequency of 76.5 GHz of a test piece molded to a thickness of 2 mm from thermoplastic resin composition A, as determined according to formula (B), is preferably 50.0% or less. The reflectance is 40.0% or less, preferably 30.0% or less, more preferably 20.0% or less, even more preferably 15.0% or less, even more preferably 10.0% or less, and even more preferably 5.0% or less. The lower limit is ideally 0%, but even if it is 0.3% or more, the required performance is sufficiently met.

[0024] The above-mentioned absorptance, transmittance, and reflectance can be achieved, for example, by not blending conductive carbon compounds such as carbon black and carbon nanotubes into thermoplastic resin composition A, or by significantly reducing the amount of such compounds blended.

[0025] Next, the components contained in the thermoplastic resin composition A will be described. The thermoplastic resin composition A is not particularly limited as long as it contains a thermoplastic resin and satisfies a predetermined transmittance. The thermoplastic resin composition A may consist of only a thermoplastic resin, or may contain a stabilizer, a release agent, a reinforcing material, and other components in addition to the thermoplastic resin. The thermoplastic resin composition A may also contain a dye. The dye may be a light-transmitting dye or a light-absorbing dye.

[0026] <<Thermoplastic Resin>> Preferred examples of the thermoplastic resin used in this embodiment include polyester resins (thermoplastic polyester resins); polyamide resins; polycarbonate resins; polystyrene-based resins; polyolefin resins such as polyethylene resins, polypropylene resins, and cyclic cycloolefin resins; polyacetal resins; polyimide resins; polyetherimide resins; polyurethane resins; polyphenylene ether resins; polyphenylene sulfide resins; polysulfone resins; polymethacrylate resins; and the like. It is more preferable that the thermoplastic resin is selected from polyester resins, polycarbonate resins, and polyamide resins, and it is even more preferable that the resin contains a polyester resin, and it is even more preferable that the resin contains a polybutylene terephthalate resin. The details of these resins are the same as those described in the thermoplastic resin composition B below, and the preferred ranges are also the same.

[0027] The content of the thermoplastic resin in the thermoplastic resin composition A in this embodiment is preferably 30% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, even more preferably 45% by mass or more, and even more preferably 50% by mass or more. By ensuring that the content is above the lower limit, the flowability during injection molding tends to be further improved. Furthermore, the content of the thermoplastic resin in the thermoplastic resin composition A may be 100% by mass, but may also be 96% by mass or less, 93% by mass or less, or 90% by mass or less. When a reinforcing material is further included, the content is preferably 85% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, and even more preferably 70% by mass or less. By ensuring that the content is below the upper limit, the mechanical strength of the resulting structure tends to be further improved. The thermoplastic resin composition A in this embodiment may contain only one type of thermoplastic resin, or may contain two or more types. When two or more types are included, the total amount is preferably within the above range.

[0028] <<Light-Transmitting Dye>> The light-transmitting dye has a high light transmittance in the wavelength range of the irradiated laser light, for example, in the wavelength range of 800 nm to 100 nm. The light-transmitting dye is not particularly limited, and any known dye can be used as long as it transmits at least a certain percentage of the laser used for laser welding. Thermoplastic resin composition A may or may not contain a light-transmitting dye. By including a light-transmitting dye, the design of the resulting structure can be improved. The light-transmitting dye refers to, for example, a dye that has a light transmittance of 70% or more when a total of 100% by weight of polybutylene terephthalate resin (e.g., Novaduran (registered trademark) 5008), 30% by weight of glass fiber (e.g., Nippon Electric Glass Co., Ltd., product name: T-127), and 0.2% by weight of a dye (a dye considered to be a light-transmitting dye) is blended. The light-transmitting dye can be selected appropriately depending on the application, and its color is not particularly limited. The light-transmitting dye used in this embodiment is preferably a black dye and / or a black dye composition. The black dye composition refers to a dye composition that exhibits black by combining two or more chromatic dyes, such as red, blue, and green. A first embodiment of the black dye composition includes a green dye and a red dye. A second embodiment of the black dye composition includes a red dye, a blue dye, and a yellow dye. The light-transmitting dye is a normal dye. Specific examples of light-transmitting dyes include naphthalocyanine, aniline black, phthalocyanine, porphyrin, perinone, quaterrylene, azo, azomethine, anthraquinone, pyrazolone, squaric acid derivatives, perylene, chromium complexes, and immonium. Azomethine, anthraquinone, and perinone are preferred, with anthraquinone and perinone being more preferred.

[0029] Examples of commercially available colorants include Plast Yellow 8000, Plast Red M 8315, Plast Red 8370, and Oil Green 5602, all manufactured by Arimoto Chemical Industry Co., Ltd.; Macrolex Yellow 3G, Macrolex Red EG, and Macrolex Green 5B, all manufactured by LANXESS Corporation; and KP Plast HK, KP Plast Red HG, KP Plast Red H2G, KP Plast Blue R, KP Plast Blue GR, and KP Plast Green G, all manufactured by Kiwa Chemical Industry Co., Ltd. Furthermore, dyes described in Japanese Patent No. 4157300 and Japanese Patent No. 4040460 can also be used, the contents of which are incorporated herein by reference.

[0030] When the thermoplastic resin composition A contains a light-transmitting dye, the content thereof is preferably 0.001 to 5 parts by mass per 100 parts by mass of the thermoplastic resin. The lower limit of the content is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and even more preferably 0.2 parts by mass or more. By setting the content at or above the lower limit, the resulting first component is colored, enhancing its design. The upper limit of the content is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, even more preferably 1 part by mass or less, even more preferably 0.8 parts by mass or less, and even more preferably 0.5 parts by mass or less. Setting the content at or below the upper limit effectively suppresses bleed-out of the light-transmitting dye. The thermoplastic resin composition A may contain only one type of light-transmitting dye, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0031] <<Light-Absorbing Dye>> The light-absorbing dye has a maximum absorption wavelength in the wavelength range of the irradiated laser light, for example, in the wavelength range of 800 nm to 1100 nm. Thermoplastic resin composition A may or may not contain a light-absorbing dye. By including a light-absorbing dye, the design of the resulting structure can be improved. The light-absorbing dye refers to a dye that, for example, when a polybutylene terephthalate resin (e.g., Novaduran (registered trademark) 5008), 30% by mass of glass fiber (e.g., Nippon Electric Glass Co., Ltd., product name: T-127), and 0.3 parts by mass of a dye (a dye believed to be a light-absorbing dye) are blended and the light transmittance is measured using the measurement method described in the Examples below (measurement of light transmittance from the opposite gate side), the transmittance is less than 20%, or even 10% or less. The light-absorbing dye is typically a pigment. Examples of the light-absorbing pigment include black pigments such as carbon black, white pigments such as titanium oxide and zinc sulfide, and chromatic pigments such as the SUMITONE CARMINE series manufactured by Sumika Color Co., Ltd. and the PV FAST series manufactured by CLARIANT Co., Ltd., and at least one or two or more of these can be used in combination. Among these, those containing carbon black are preferred. As the carbon black, at least one or two or more of furnace black, thermal black, channel black, lamp black, and acetylene black can be used in combination. It is also preferred to use carbon black that has been pre-masterbatched to facilitate dispersion.

[0032] When the thermoplastic resin composition A contains a light-absorbing dye, the content thereof is preferably 0.001 to 5 parts by mass per 100 parts by mass of the thermoplastic resin. The lower limit of the content is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and even more preferably 0.2 parts by mass or more. By setting the content at or above the lower limit, the resulting first component is colored, enhancing its design. The upper limit of the content is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, even more preferably 1 part by mass or less, even more preferably 0.8 parts by mass or less, and even more preferably 0.5 parts by mass or less. Setting the content at or below the upper limit effectively suppresses bleed-out of the light-absorbing dye. The thermoplastic resin composition A may contain only one type of light-absorbing dye, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range. Furthermore, the dye contained in the thermoplastic resin composition A is preferably 95% by mass or more, more preferably 98% by mass or more, and even more preferably 99% by mass or more of either a light-transmitting dye or a light-absorbing dye.

[0033] <<Reinforcing Material>> The thermoplastic resin composition A in this embodiment may contain a reinforcing material. By containing a reinforcing material, the mechanical strength of the obtained structure can be improved. Details of the reinforcing material are the same as those of the reinforcing material that may be blended into the thermoplastic resin composition B described below, and the preferred range is also the same.

[0034] The thermoplastic resin composition A in this embodiment preferably contains 10 parts by mass or more of a reinforcing material (preferably glass fiber) per 100 parts by mass of the thermoplastic resin (preferably polybutylene terephthalate resin), more preferably 20 parts by mass or more, even more preferably 35 parts by mass or more, and even more preferably 48 parts by mass or more. By setting the content at or above the lower limit, the mechanical strength of the resulting structure tends to be further increased. Furthermore, the content of the reinforcing material (preferably glass fiber) is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less, per 100 parts by mass of the thermoplastic resin (preferably polybutylene terephthalate resin). By setting the content at or below the upper limit, the appearance of the structure tends to be improved, and the flowability of the thermoplastic resin composition A tends to be further improved.

[0035] The content of the reinforcing material (preferably glass fiber) in the thermoplastic resin composition A in this embodiment is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and even more preferably 25% by mass or more in the thermoplastic resin composition A. The content of the reinforcing material (preferably glass fiber) in the thermoplastic resin composition A is more preferably 50% by mass or less, even more preferably 45% by mass or less, even more preferably 40% by mass or less, and even more preferably 35% by mass or less. By setting the content to be equal to or greater than the lower limit, the mechanical strength tends to be further increased. By setting the content to be equal to or less than the upper limit, the appearance of the structure tends to be improved, and the fluidity of the thermoplastic resin composition A when melted tends to be further improved. The thermoplastic resin composition A in this embodiment may contain only one type of reinforcing material (preferably glass fiber), or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0036] <<Other Components>> The thermoplastic resin composition A of this embodiment may contain other components in addition to those described above, as necessary, as long as the desired physical properties are not significantly impaired. Examples of other components include various resin additives. The other components may be contained alone or in any combination and ratio of two or more. Specific examples include reactive compounds such as stabilizers, release agents, flame retardants, and moisture-heat resistance improvers, impact resistance improvers, nucleating agents, UV absorbers, antistatic agents, antifogging agents, antiblocking agents, flow improvers, plasticizers, dispersants, antibacterial agents, and laser print improvers. The thermoplastic resin composition A of this embodiment may contain at least one stabilizer and release agent. Details of the stabilizer and release agent are the same as those of the stabilizer and release agent that may be blended in the thermoplastic resin composition B described below, and the preferred ranges are also the same. The blend amounts are preferably within the same ranges. Furthermore, the thermoplastic resin composition A of this embodiment preferably does not substantially contain a conductive carbon compound (or a conductive compound). "Substantially free of conductive carbon compounds (and further conductive compounds)" means that the content of conductive carbon compounds (and further conductive compounds) is, for example, less than 0.01 parts by mass, preferably less than 0.001 parts by mass, and more preferably less than 0.0001 parts by mass, per 100 parts by mass of the thermoplastic resin. Furthermore, the thermoplastic resin composition A in this embodiment may be used after being laser-printed.

[0037] <Thermoplastic Resin Composition B> Thermoplastic resin composition B is a resin composition containing a thermoplastic resin, and a test piece molded to a thickness of 2 mm has a transmittance of less than 50.0% at a frequency of 76.5 GHz, as calculated according to formula (C), and a test piece molded to a thickness of 2 mm has an absorptance of 40.0% or more at a frequency of 76.5 GHz, as calculated according to formula (A). By achieving a transmittance of less than 50.0%, electromagnetic noise can be effectively suppressed and electromagnetic waves opposing the second member can be made less likely to pass through. Furthermore, when a housing is formed including a first member and a second member, electromagnetic waves leaking from the inside can be made less likely to pass through. The above absorptance, transmittance, and reflectance can be achieved by using, for example, a conductive carbon compound such as carbon nanotubes.

[0038] The transmittance (2 mm thick) is less than 50.0%, preferably 45.0% or less, more preferably 38.0% or less, even more preferably 25.0% or less, even more preferably 10.0% or less, and even more preferably 5.0% or less. By setting it to the upper limit or less, electromagnetic noise that affects the element or is emitted from the element tends to be more effectively suppressed. Furthermore, the lower limit of the transmittance may be 0%, but 0.1% or more is practical.

[0039] Furthermore, when the thermoplastic resin composition B is molded into a 3 mm thickness (preferably, 100 mm × 100 mm × 3 mm thickness), the transmittance calculated according to formula (C) at a frequency of 76.5 GHz is preferably 26.0% or less. The transmittance (3 mm thickness) is preferably 24.0% or less, more preferably 21.0% or less, and even more preferably 15.0% or less. The lower limit is ideally 0%, but even if it is 4.0% or more, the required performance is sufficiently met.

[0040] The absorbency (2 mm thickness) is 40.0% or more, preferably 45.0% or more, more preferably 50.0% or more, even more preferably 55.0% or more, even more preferably 60.0% or more, and even more preferably 65.0% or more. The upper limit is ideally 100%, but even if it is 90.0% or less, the required performance is sufficiently met.

[0041] Furthermore, when thermoplastic resin composition B is molded into a 3 mm thickness (preferably, 100 mm x 100 mm x 3 mm thickness), the absorbance calculated according to formula (A) at a frequency of 76.5 GHz is preferably 63.0 to 100%. The absorbance (3 mm thickness) is preferably 57.0% or more, more preferably 59.0% or more, even more preferably 64.0% or more, even more preferably 66.0% or more, and even more preferably 70.0% or more. While an upper limit of 100% is ideal, the required performance is fully satisfied even if the absorbance is 90.0% or less.

[0042] In this embodiment, the reflectance at a frequency of 76.5 GHz of a test piece obtained by molding thermoplastic resin composition B to a thickness of 2 mm, as determined according to formula (B), is preferably 50.0% or less. The reflectance (2 mm thickness) is preferably 45.0% or less, more preferably 40.0% or less, even more preferably 35.0% or less, even more preferably 30.0% or less, and even more preferably 25.0% or less. The lower limit is ideally 0%, but even if it is 1.0% or more, the required performance is sufficiently met.

[0043] Furthermore, when thermoplastic resin composition B is molded into a 3 mm thickness (preferably 100 mm × 100 mm × 3 mm thickness), the reflectance calculated according to formula (B) at a frequency of 76.5 GHz is preferably 38.0% or less. The reflectance (3 mm thickness) is preferably 33.0% or less, more preferably 28.0% or less, even more preferably 24.0% or less, even more preferably 20.0% or less, and even more preferably 16.5% or less. Although a lower limit of 0% is ideal, a reflectance of 3.0% or more, or even 8.0% or more, will fully satisfy the required performance.

[0044] Next, the components contained in the thermoplastic resin composition B will be described. The thermoplastic resin composition B is not particularly limited as long as it contains a thermoplastic resin and satisfies the predetermined transmittance and absorbance. The thermoplastic resin composition B preferably contains a thermoplastic resin and a conductive compound, and may further contain a stabilizer, a release agent, a reinforcing material, and other components.

[0045] <<Thermoplastic Resin>> Preferred examples of the thermoplastic resin used in this embodiment include polyester resins (thermoplastic polyester resins); polyamide resins; polycarbonate resins; polystyrene-based resins; polyolefin resins such as polyethylene resins, polypropylene resins, and cyclic cycloolefin resins; polyacetal resins; polyimide resins; polyetherimide resins; polyurethane resins; polyphenylene ether resins; polyphenylene sulfide resins; polysulfone resins; polymethacrylate resins; and the like. The thermoplastic resin is more preferably selected from polyester resins, polycarbonate resins, and polyamide resins, even more preferably contains a polyester resin, and even more preferably contains a polybutylene terephthalate resin. Each thermoplastic resin will be described in detail below.

[0046] <<Polyester Resin>> As the polyester resin, known thermoplastic polyester resins can be used, and polyethylene terephthalate resin and polybutylene terephthalate resin are preferred, and it is more preferred to include at least a polybutylene terephthalate resin. The polybutylene terephthalate resin used in the resin composition of this embodiment is a polyester resin having a structure in which terephthalic acid units and 1,4-butanediol units are ester-bonded, and includes, in addition to polybutylene terephthalate resin (homopolymer), a polybutylene terephthalate copolymer containing other copolymerization components other than terephthalic acid units and 1,4-butanediol units, and a mixture of a homopolymer and a polybutylene terephthalate copolymer.

[0047] The polybutylene terephthalate resin may contain one or more dicarboxylic acid units other than terephthalic acid. Specific examples of the other dicarboxylic acids include aromatic dicarboxylic acids such as isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyl-2,2'-dicarboxylic acid, biphenyl-3,3'-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, bis(4,4'-carboxyphenyl)methane, anthracenedicarboxylic acid, and 4,4'-diphenyletherdicarboxylic acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and 4,4'-dicyclohexyldicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, and dimer acid. In the polybutylene terephthalate resin used in this embodiment, terephthalic acid units preferably account for 80 mol % or more, and more preferably 90 mol % or more, of all dicarboxylic acid units.

[0048] The diol unit may contain one or more other diol units in addition to 1,4-butanediol. Specific examples of other diol units include aliphatic or alicyclic diols having 2 to 20 carbon atoms, bisphenol derivatives, and the like. Specific examples include ethylene glycol, propylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, decamethylene glycol, cyclohexanedimethanol, 4,4'-dicyclohexylhydroxymethane, 4,4'-dicyclohexylhydroxypropane, and ethylene oxide addition diol of bisphenol A. In addition to the above-mentioned bifunctional monomers, small amounts of trifunctional monomers such as trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol, and trimethylolpropane can also be used in combination to introduce a branched structure, or monofunctional compounds such as fatty acids can be used in combination to adjust the molecular weight. In the polybutylene terephthalate resin used in this embodiment, 1,4-butanediol units preferably account for 80 mol % or more, and more preferably 90 mol % or more, of all diol units.

[0049] As described above, the polybutylene terephthalate resin is preferably a polybutylene terephthalate homopolymer obtained by polycondensation of terephthalic acid and 1,4-butanediol. Alternatively, the polybutylene terephthalate copolymer may contain, as the carboxylic acid unit, one or more dicarboxylic acids other than the aforementioned terephthalic acid and / or, as the diol unit, one or more diols other than the aforementioned 1,4-butanediol. When the polybutylene terephthalate resin is a polybutylene terephthalate resin modified by copolymerization, specific preferred copolymers include polyester ether resins copolymerized with polyalkylene glycols, particularly polytetramethylene glycol, dimer acid-copolymerized polybutylene terephthalate resins, and isophthalic acid-copolymerized polybutylene terephthalate resins. Of these, polyester ether resins copolymerized with polytetramethylene glycol are preferred. These copolymers refer to those in which the copolymerization amount is 1 mol% or more but less than 50 mol% of the total polybutylene terephthalate resin segments. In particular, the copolymerization amount is preferably 2 mol % or more but less than 50 mol %, more preferably 3 to 40 mol %, and even more preferably 5 to 20 mol %. By setting the copolymerization ratio in this range, fluidity, toughness, and tracking resistance tend to be easily improved, which is preferable.

[0050] The amount of terminal carboxyl groups in the polybutylene terephthalate resin may be appropriately selected and determined, but is usually 60 eq / ton or less, preferably 50 eq / ton or less, and more preferably 30 eq / ton or less. By setting the amount to the above upper limit or less, alkali resistance and hydrolysis resistance tend to be improved. The lower limit of the amount of terminal carboxyl groups is not particularly specified, but is usually 10 eq / ton or more, taking into consideration the productivity of polybutylene terephthalate resin production.

[0051] The amount of terminal carboxyl groups in the polybutylene terephthalate resin is a value measured by dissolving 0.5 g of the polybutylene terephthalate resin in 25 mL of benzyl alcohol and titrating the solution with a 0.01 mol / L benzyl alcohol solution of sodium hydroxide. The amount of terminal carboxyl groups can be adjusted by any conventionally known method, such as adjusting the polymerization conditions during polymerization, such as the raw material charge ratio, polymerization temperature, and pressure reduction method, or by reacting a terminal blocking agent.

[0052] The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.5 to 2 dL / g. From the viewpoint of moldability and mechanical properties, an intrinsic viscosity in the range of 0.6 to 1.5 dL / g is more preferable. By setting the intrinsic viscosity to 0.5 dL / g or more, the mechanical strength of the resulting resin composition tends to be further improved. Furthermore, by setting the intrinsic viscosity to 2 dL / g or less, the fluidity of the resin composition tends to be further improved, and moldability tends to be improved. The intrinsic viscosity of the polybutylene terephthalate resin is a value measured at 30°C in a mixed solvent of tetrachloroethane and phenol in a 1:1 (mass ratio).

[0053] Polybutylene terephthalate resin can be produced by batch or continuous melt polymerization of a dicarboxylic acid component containing terephthalic acid as the main component or an ester derivative thereof with a diol component containing 1,4-butanediol as the main component. Alternatively, after producing a low-molecular-weight polybutylene terephthalate resin by melt polymerization, the degree of polymerization (or molecular weight) can be increased to a desired value by further solid-state polymerization under a nitrogen gas flow or reduced pressure. The polybutylene terephthalate resin is preferably produced by a continuous melt polycondensation process of a dicarboxylic acid component containing terephthalic acid as the main component and a diol component containing 1,4-butanediol as the main component.

[0054] The catalyst used in carrying out the esterification reaction may be a conventionally known catalyst, such as a titanium compound, a tin compound, a magnesium compound, or a calcium compound. Among these, titanium compounds are particularly preferred. Specific examples of titanium compounds used as esterification catalysts include titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate.

[0055] In addition to the above, the polyester resin may be found in paragraphs 0013 to 0016 of JP-A-2010-174223, the contents of which are incorporated herein by reference.

[0056] <<Polycarbonate Resin>> Polycarbonate resins are optionally branched homopolymers or copolymers obtained by reacting a dihydroxy compound or a small amount of a polyhydroxy compound with phosgene or a carbonate diester. The method for producing the polycarbonate resin is not particularly limited, and polycarbonate resins produced by the conventionally known phosgene method (interfacial polymerization method) or melt method (ester exchange method) can be used.

[0057] The dihydroxy compound used as the raw material is preferably an aromatic dihydroxy compound, and examples thereof include 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), tetramethylbisphenol A, bis(4-hydroxyphenyl)-p-diisopropylbenzene, hydroquinone, resorcinol, and 4,4-dihydroxydiphenyl, with bisphenol A being preferred. Also usable are compounds in which one or more tetraalkylphosphonium sulfonates are bonded to the above aromatic dihydroxy compounds.

[0058] Among the polycarbonate resins mentioned above, aromatic polycarbonate resins derived from 2,2-bis(4-hydroxyphenyl)propane or aromatic polycarbonate copolymers derived from 2,2-bis(4-hydroxyphenyl)propane and other aromatic dihydroxy compounds are preferred. Furthermore, copolymers primarily composed of aromatic polycarbonate resins, such as copolymers with polymers or oligomers having a siloxane structure, may also be used. Furthermore, two or more of the above-mentioned polycarbonate resins may be mixed and used.

[0059] To adjust the molecular weight of the polycarbonate resin, a monovalent aromatic hydroxy compound may be used, such as m- and p-methylphenol, m- and p-propylphenol, p-tert-butylphenol, and p-long-chain alkyl-substituted phenol.

[0060] The viscosity average molecular weight (Mv) of the polycarbonate resin is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 13,000 or more. By using a polycarbonate resin with a viscosity average molecular weight of 5,000 or more, the mechanical strength of the resulting resin composition tends to be further improved. Furthermore, the viscosity average molecular weight (Mv) of the polycarbonate resin is preferably 60,000 or less, more preferably 40,000 or less, and even more preferably 30,000 or less. By using a polycarbonate resin with a viscosity average molecular weight of 60,000 or less, the fluidity of the resin composition tends to be improved, and moldability tends to be improved. When two or more polycarbonate resins are contained, it is preferable that the mixture satisfies the above range (hereinafter, the same applies to molecular weight).

[0061] In this embodiment, the viscosity average molecular weight (Mv) of the polycarbonate resin is a value calculated from the intrinsic viscosity ([η]) obtained by measuring the viscosity of a methylene chloride solution of the polycarbonate resin at 20°C using an Ubbelohde viscometer, and then using the following Schnell viscosity formula: [η] = 1.23 × 10 －４ Mv ０．８３

[0062] The method for producing the polycarbonate resin is not particularly limited, and polycarbonate resins produced by either the phosgene method (interfacial polymerization method) or the melt method (ester interchange method) can be used. Also preferred is a polycarbonate resin produced by the melt method and then subjected to post-treatment to adjust the amount of terminal OH groups.

[0063] <<Polyamide Resin>> Polyamide resins are polymers whose structural units are acid amides obtained by ring-opening polymerization of lactams, polycondensation of aminocarboxylic acids, or polycondensation of diamines and dibasic acids, and may be aliphatic polyamide resins or semi-aromatic polyamide resins. Specific examples include polyamide 6, 11, 12, 46, 66, 610, 612, 6I, 6 / 66, 6T / 6I, 6 / 6T, 66 / 6T, 66 / 6T / 6I, 9T, and 10T, xylylenediamine-based polyamide resins (described in detail below), polytrimethylhexamethylene terephthalamide, polybis(4-aminocyclohexyl)methanedodecamide, polybis(3-methyl-4-aminocyclohexyl)methanedodecamide, and polyundecamethylenehexahydroterephthalamide. The "I" in the above text represents an isophthalic acid component, and the "T" represents a terephthalic acid component. Regarding the polyamide resin, the description in paragraphs 0011 to 0013 of JP-A-2011-132550 can be referred to, the contents of which are incorporated herein by reference.

[0064] The polyamide resin used in this embodiment is composed of diamine-derived structural units and dicarboxylic acid-derived structural units, and is preferably a xylylenediamine-based polyamide resin in which 50 mol% or more of the diamine-derived structural units are derived from xylylenediamine. The diamine-derived structural units of the xylylenediamine-based polyamide resin are preferably derived from at least one of meta-xylylenediamine and para-xylylenediamine, with 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more of the diamine-derived structural units being derived from at least one of meta-xylylenediamine and para-xylylenediamine. The dicarboxylic acid-derived structural units of the xylylenediamine-based polyamide resin are preferably derived from α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms, with 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more of the dicarboxylic acid-derived structural units being derived from α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms. Suitable α,ω-straight chain aliphatic dibasic acids having 4 to 20 carbon atoms include adipic acid, sebacic acid, suberic acid, dodecanedioic acid, and eicodionic acid, with adipic acid and sebacic acid being more preferred.

[0065] Diamines other than metaxylylenediamine and paraxylylenediamine that can be used as raw diamine components for xylylenediamine-based polyamide resins include aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, and 2,4,4-trimethylhexamethylenediamine; 1,3-bis( Examples of the diamine include alicyclic diamines such as bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminomethyl)decalin, and bis(aminomethyl)tricyclodecane; and diamines having an aromatic ring such as bis(4-aminophenyl)ether, paraphenylenediamine, and bis(aminomethyl)naphthalene, and these can be used alone or in combination of two or more.

[0066] Examples of dicarboxylic acid components other than the above-mentioned α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms include phthalic acid compounds such as isophthalic acid, terephthalic acid, and orthophthalic acid, and isomers of naphthalenedicarboxylic acids such as 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid, and these can be used alone or in combination of two or more.

[0067] <<Polystyrene-Based Resin>> Examples of polystyrene-based resins include homopolymers of styrene-based monomers and copolymers of styrene-based monomers and monomers copolymerizable with styrene-based monomers. Examples of styrene-based monomers include styrene, α-methylstyrene, chlorostyrene, methylstyrene, and tert-butylstyrene. In the styrene-based resin of this embodiment, 50 mol% or more of the monomer units are styrene-based monomers. More specific examples of polystyrene-based resins include polystyrene resin, acrylonitrile-styrene copolymer (AS resin), high-impact polystyrene resin (HIPS), acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), acrylonitrile-styrene-acrylic rubber copolymer (ASA resin), acrylonitrile-ethylene propylene rubber-styrene copolymer (AES resin), and styrene-IPN type rubber copolymer. In this embodiment, the styrene-based resin is preferably an acrylonitrile-styrene copolymer (AS resin), high impact polystyrene resin (HIPS), acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), acrylonitrile-styrene-acrylic rubber copolymer (ASA resin), acrylonitrile-ethylene propylene rubber-styrene copolymer (AES resin), or styrene-IPN type rubber copolymer, more preferably a high impact polystyrene resin (HIPS), and even more preferably a butadiene rubber-containing polystyrene.

[0068] When the polystyrene-based resin contains a rubber component, the content of the rubber component in the polystyrene-based resin is preferably 3 to 70% by mass, more preferably 5 to 50% by mass, and even more preferably 7 to 30% by mass. A rubber component content of 3% by mass or more tends to improve impact resistance, and a rubber component content of 70% by mass or less tends to improve flame retardancy, which is preferable. The average particle size of the rubber component is preferably 0.05 to 10 μm, more preferably 0.1 to 6 μm, and even more preferably 0.2 to 3 μm. An average particle size of 0.05 μm or more tends to improve impact resistance, and an average particle size of 10 μm or less tends to improve appearance, which is preferable.

[0069] The weight-average molecular weight of the polystyrene resin is usually 50,000 or more, preferably 100,000 or more, more preferably 150,000 or more, and usually 500,000 or less, preferably 400,000 or less, more preferably 300,000 or less. The number-average molecular weight is usually 10,000 or more, preferably 30,000 or more, more preferably 50,000 or more, and preferably 500,000 or less, more preferably 300,000 or less.

[0070] The melt flow rate (MFR) of the polystyrene resin, measured in accordance with JIS K7210 (temperature 200°C, load 5 kgf), is preferably 0.1 to 30 g / 10 min, more preferably 0.5 to 25 g / 10 min. An MFR of 0.1 g / 10 min or more tends to improve fluidity, while an MFR of 30 g / 10 min or less tends to improve impact resistance.

[0071] Examples of methods for producing such polystyrene resins include known methods such as emulsion polymerization, solution polymerization, suspension polymerization, and bulk polymerization.

[0072] The content of the thermoplastic resin in the thermoplastic resin composition B in this embodiment is preferably 30% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, even more preferably 45% by mass or more, and even more preferably 50% by mass or more. By ensuring that the content is equal to or greater than the lower limit, fluidity during injection molding tends to be further improved. Furthermore, the content of the thermoplastic resin in the thermoplastic resin composition B is more preferably 96% by mass or less, even more preferably 93% by mass or less, and may even be 90% by mass or less. When a reinforcing material is further included, the content is preferably 85% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, and even more preferably 70% by mass or less. By ensuring that the content is equal to or less than the upper limit, the mechanical strength of the resulting structure tends to be further improved. The thermoplastic resin composition B in this embodiment may contain only one type of thermoplastic resin, or may contain two or more types. When two or more types are included, the total amount is preferably within the above range.

[0073] <<Conductive Compound>> The thermoplastic resin composition B in this embodiment preferably contains a conductive compound. By including a conductive compound, the absorbance of the second member can be increased. Furthermore, the reflectance and transmittance of the second member can be reduced. Examples of the conductive compound used in this embodiment include metals, metal oxides, conductive carbon compounds, and conductive polymers, with conductive carbon compounds being preferred. Examples of metals include copper, nickel, silver, and stainless steel, with metal fillers, stainless steel fibers, and magnetic fillers being preferred. Examples of metal oxides include alumina and zinc oxide, with alumina fibers and zinc oxide nanotubes being preferred. Examples of conductive carbon compounds include carbon black, graphene, graphite, fullerenes, carbon nanocoils, carbon nanotubes, and carbon fibers, with carbon nanotubes being more preferred. Fibers coated with metals, metal oxides, or conductive carbon compounds are also preferred. Examples include carbon-coated potassium titanate whiskers and metal-coated fibers.

[0074] The conductive compound in this embodiment is preferably a relatively thin and long shape, such as a fiber, tube, or whisker. The diameter (number average fiber diameter) of the conductive compound is preferably 0.5 to 100 nm, more preferably 1 to 30 nm. From the viewpoint of imparting good electromagnetic wave absorption properties, the aspect ratio of the conductive compound is preferably 5 or more, more preferably 50 or more. There is no particular upper limit, but it is, for example, 500 or less.

[0075] The conductive carbon compound used in this embodiment is preferably carbon nanotubes. The carbon nanotubes are single-walled carbon nanotubes and / or multi-walled carbon nanotubes, and preferably contain at least multi-walled carbon nanotubes. Carbon materials partially having a carbon nanotube structure can also be used. The carbon nanotubes are not limited to a cylindrical shape, and may have a coiled shape with a spiral at a pitch of 1 μm or less. Carbon nanotubes are commercially available, and examples of such carbon nanotubes include those available from Bayer MaterialScience, Nanosil, Showa Denko K.K., and Hyperion Catalysis International. In addition to the name carbon nanotubes, they may also be called graphite fibrils, carbon fibrils, carbon nanofibers, carbon nanostructures, etc.

[0076] In this embodiment, the conductive compound may be blended in the form of a masterbatch with a thermoplastic resin. In this case, the thermoplastic resin is selected from the thermoplastic resins described above. For example, when the main thermoplastic resin is polybutylene terephthalate resin, the thermoplastic resin used for masterbatching is preferably polybutylene terephthalate resin, polystyrene-based resin, polyolefin resin, or polycarbonate resin, with polybutylene terephthalate resin and polystyrene-based resin being more preferred. The concentration of the thermoplastic resin used for masterbatching is preferably 99.5% by mass or less, more preferably 95% by mass or less, and also preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 30% by mass or more, and even more preferably 50% by mass or more. By setting the concentration within the above upper and lower limits, the dispersibility of the conductive compound (especially the conductive carbon compound) in the main thermoplastic resin tends to be further improved. It goes without saying that the main thermoplastic resin does not need to be a single type, as described above, but may be a mixture of two or more types.

[0077] The content of the conductive compound (preferably carbon nanotubes) in the thermoplastic resin composition B in this embodiment is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.10% by mass or more, and may be 0.20% by mass or more, even 0.40% by mass or more, particularly 0.50% by mass or more, or even 0.70% by mass or more. By setting the content at or above the lower limit, electromagnetic wave absorption properties are effectively exhibited. Furthermore, the content of the conductive compound (preferably carbon nanotubes) in the thermoplastic resin composition B in this embodiment is preferably 10.0% by mass or less, more preferably 8.0% by mass or less, even more preferably 6.0% by mass or less, even more preferably 4.0% by mass or less, even more preferably 3.0% by mass or less, and may be 2.0% by mass or less. By setting the content at or below the upper limit, the fluidity of the resin tends to be further improved.

[0078] The thermoplastic resin composition B in this embodiment also preferably contains 0.01 parts by mass or more of a conductive compound (preferably carbon nanotubes) relative to 100 parts by mass of the thermoplastic resin, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, even more preferably 0.5 parts by mass or more, and even more preferably 1.0 parts by mass or more. By ensuring that the amount is above the lower limit, electromagnetic wave absorption properties are effectively exhibited. The thermoplastic resin composition B in this embodiment also preferably contains 10.0 parts by mass or less of a conductive compound (preferably carbon nanotubes) relative to 100 parts by mass of the thermoplastic resin, more preferably 8.0 parts by mass or less, even more preferably 6.0 parts by mass or less, even more preferably 4.0 parts by mass or less, even more preferably 3.0 parts by mass or less, and even optionally 2.5 parts by mass or less. By ensuring that the amount is below the upper limit, the fluidity of the resin tends to be further improved. The thermoplastic resin composition B in this embodiment may contain only one type of conductive compound, or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0079] <<Reinforcing Material>> The thermoplastic resin composition B in this embodiment may contain a reinforcing material. By containing a reinforcing material, the mechanical strength of the obtained structure can be improved. The reinforcing material that can be used in this embodiment is not particularly limited, and may be any of fibers, fillers, beads, etc., although fibers are preferred.

[0080] When the reinforcing material is a fiber, it may be a short fiber or a long fiber. When the reinforcing material is a short fiber, filler, beads, or the like, examples of the thermoplastic resin composition B in this embodiment include pellets, powdered pellets, and films formed from the pellets. When the reinforcing material is a long fiber, examples of the reinforcing material include long fibers for so-called unidirectional (UD) materials, and sheet-like long fibers such as woven fabrics and knitted fabrics. When these long fibers are used, components other than the reinforcing material of the thermoplastic resin composition B in this embodiment can be impregnated into the sheet-like long fiber reinforcing material to form a sheet-like thermoplastic resin composition B (e.g., a prepreg).

[0081] Examples of raw materials for the reinforcing material include inorganic substances such as glass, carbon (carbon fiber, etc.), alumina, boron, ceramics, and metals (steel, etc.), and organic substances such as plants (including kenaf, bamboo, etc.), aramid, polyoxymethylene, aromatic polyamide, polyparaphenylene benzobisoxazole, and ultra-high molecular weight polyethylene, with glass being preferred.

[0082] In this embodiment, the thermoplastic resin composition B preferably contains glass fibers as a reinforcing material. The glass fibers are selected from glass compositions such as A-glass, C-glass, E-glass, R-glass, D-glass, M-glass, and S-glass, with E-glass (alkali-free glass) being particularly preferred. Glass fibers refer to fibrous materials having a circular or polygonal cross section cut perpendicular to the longitudinal direction. The number-average fiber diameter of the glass fibers per single fiber is typically 1 to 25 μm, preferably 5 to 17 μm. By setting the number-average fiber diameter to 1 μm or more, the moldability of the thermoplastic resin composition B tends to be further improved. By setting the number-average fiber diameter to 25 μm or less, the appearance of the resulting structure tends to be improved, and the reinforcing effect also tends to be improved. The glass fibers may be single fibers or multiple single fibers twisted together. The glass fiber may be in the form of a glass roving obtained by continuously winding a single fiber or a plurality of twisted fibers, a chopped strand cut to a length of 1 to 10 mm (i.e., glass fiber having a number average fiber length of 1 to 10 mm), or a milled fiber pulverized to a length of about 10 to 500 μm (i.e., glass fiber having a number average fiber length of 10 to 500 μm). However, chopped strands cut to a length of 1 to 10 mm are preferred. Glass fibers of different forms can also be used in combination. Glass fibers having an irregular cross-sectional shape are also preferred. This irregular cross-sectional shape refers to a shape in which the flatness, expressed as the ratio of the major axis to the minor axis of the cross section perpendicular to the longitudinal direction of the fiber, is, for example, 1.5 to 10, preferably 2.5 to 10, more preferably 2.5 to 8, and particularly preferably 2.5 to 5.

[0083] The glass fiber may be surface-treated with, for example, a silane-based compound, an epoxy-based compound, a urethane-based compound, or the like, or may be oxidized, in order to improve its affinity with the resin component, as long as the properties of the thermoplastic resin composition B in this embodiment are not significantly impaired.

[0084] In this embodiment, the thermoplastic resin composition B preferably contains 10 parts by mass or more of a reinforcing material (preferably glass fiber) per 100 parts by mass of the thermoplastic resin (preferably polybutylene terephthalate resin), more preferably 20 parts by mass or more, even more preferably 35 parts by mass or more, and even more preferably 48 parts by mass or more. By setting the content at or above the lower limit, the mechanical strength of the resulting structure tends to be further increased. Furthermore, the content of the reinforcing material (preferably glass fiber) is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less, per 100 parts by mass of the thermoplastic resin (preferably polybutylene terephthalate resin). By setting the content at or below the upper limit, the appearance of the structure tends to be improved, and the flowability of the thermoplastic resin composition B tends to be further improved.

[0085] The content of the reinforcing material (preferably glass fiber) in the thermoplastic resin composition B in this embodiment is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and even more preferably 25% by mass or more in the thermoplastic resin composition B. The content of the reinforcing material (preferably glass fiber) in the thermoplastic resin composition B is more preferably 50% by mass or less, even more preferably 45% by mass or less, even more preferably 40% by mass or less, and even more preferably 35% by mass or less. By setting the content to be equal to or greater than the lower limit, the mechanical strength tends to be further increased. By setting the content to be equal to or less than the upper limit, the appearance of the structure tends to be improved, and the fluidity of the thermoplastic resin composition B when melted tends to be further improved. The thermoplastic resin composition B in this embodiment may contain only one type of reinforcing material (preferably glass fiber), or may contain two or more types. When two or more types are contained, the total amount is preferably within the above range.

[0086] <<Stabilizer>> The thermoplastic resin composition B in this embodiment may contain a stabilizer, and preferably contains a phosphorus-based stabilizer and / or a phenol-based stabilizer.

[0087] Any known phosphorus stabilizer can be used. Specific examples include phosphorus oxoacids such as phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, and polyphosphoric acid; metal acid pyrophosphates such as sodium acid pyrophosphate, potassium acid pyrophosphate, and calcium acid pyrophosphate; phosphates of Group 1 or Group 2B metals such as potassium phosphate, sodium phosphate, cesium phosphate, and zinc phosphate; organic phosphate compounds, organic phosphite compounds, and organic phosphonite compounds, with organic phosphite compounds being particularly preferred. Examples of phenolic stabilizers include hindered phenolic antioxidants. For details, please refer to the descriptions in paragraphs 0105 to 0111 of WO 2020 / 013127, the contents of which are incorporated herein by reference.

[0088] The content of the stabilizer is usually 0.001 parts by mass or more, preferably 0.01 parts by mass or more, and usually 1 part by mass or less, preferably 0.5 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin. By setting the content of the stabilizer to be equal to or greater than the lower limit of the above range, the effect as a stabilizer can be obtained more effectively. Furthermore, by setting the content of the stabilizer to be equal to or less than the upper limit of the above range, the effect does not plateau, which is economical. The thermoplastic resin composition B in this embodiment may contain only one type of stabilizer, or may contain two or more types. When two or more types are contained, it is preferable that the total amount is within the above range.

[0089] <<Release Agent>> The thermoplastic resin composition B in this embodiment preferably contains a release agent (lubricant). Examples of release agents include aliphatic carboxylic acids, esters of aliphatic carboxylic acids and alcohols, aliphatic hydrocarbon compounds having a number average molecular weight of 200 to 15,000, waxes, and polysiloxane-based silicone oils. For details of these, please refer to paragraphs 0112 to 0121 of WO 2020 / 013127, the contents of which are incorporated herein by reference.

[0090] The content of the release agent is usually 0.001 part by mass or more, preferably 0.01 part by mass or more, and usually 2 parts by mass or less, preferably 1 part by mass or less, relative to 100 parts by mass of the thermoplastic resin. By setting the content of the release agent to be equal to or more than the lower limit of the above range, it is easy to obtain a sufficient effect of mold releasability, and by setting the content of the release agent to be equal to or less than the upper limit of the above range, sufficient hydrolysis resistance is obtained and mold contamination during injection molding is less likely to occur.

[0091] <<Other Components>> The thermoplastic resin composition B of this embodiment may contain other components in addition to those described above, as necessary, as long as the desired physical properties are not significantly impaired. Examples of other components include various resin additives. The other components may be contained alone or in any combination and ratio of two or more. Specific examples include flame retardants, reactive compounds (e.g., epoxy compounds), pigments, dyes, UV absorbers, antistatic agents, antifogging agents, antiblocking agents, flow improvers, plasticizers, dispersants, and antibacterial agents. The thermoplastic resin composition B of this embodiment preferably contains at least one stabilizer and mold release agent. The thermoplastic resin composition B of this embodiment is adjusted so that the total of the thermoplastic resin (preferably polybutylene terephthalate resin) and other optional components is 100% by mass. In the thermoplastic resin composition B of this embodiment, the total of the thermoplastic resin, conductive compound (preferably carbon nanotubes), and reinforcing material (preferably glass fiber) preferably accounts for 95% by mass or more of the thermoplastic resin composition B. In addition, in the thermoplastic resin composition B of this embodiment, the total of the thermoplastic resin, conductive compound, reinforcing material, stabilizer, and release agent preferably accounts for 99% by mass or more of the thermoplastic resin composition B. Furthermore, in this embodiment, the thermoplastic resin composition B preferably does not substantially contain a light-absorbing dye (e.g., a dye having a maximum absorption wavelength in the wavelength range of 800 nm to 1100 nm, a black colorant, etc.). However, the light-absorbing dye here is intended to exclude those that also fall under the category of conductive compounds. Furthermore, the thermoplastic resin composition B may be in a form that is substantially free of carbon black. "Substantially free" means, for example, less than 0.01 parts by mass, preferably less than 0.001 parts by mass, and more preferably less than 0.0001 parts by mass, per 100 parts by mass of the thermoplastic resin.

[0092] <Thermoplastic Resin Composition A and Thermoplastic Resin Composition B> In this embodiment, the difference between the absorptance of a test piece molded to a thickness of 2 mm from thermoplastic resin composition A at a frequency of 76.5 GHz, as determined according to formula (A), and the absorptance of a test piece molded to a thickness of 2 mm from thermoplastic resin composition B at a frequency of 76.5 GHz, as determined according to formula (A), is preferably 40% or more. By adopting such a configuration, for example, the directionality of the electromagnetic waves emitted from the element can be improved. The difference in absorptance is preferably 40% or more, and more preferably 50% or more. Furthermore, the upper limit of the difference in absorptance is ideally 100%, but even a value of 90% or less sufficiently satisfies the required performance. The low radar absorptance of the first component and the high absorptance of the second component can be expected to improve the directionality of the emitted electromagnetic waves while simultaneously reducing unnecessary noise. In this embodiment, the resin components contained in thermoplastic resin composition A and thermoplastic resin composition B preferably share 80% by mass, more preferably 90% by mass or more, and even more preferably 95% by mass or more. In this way, the resin components contained in the thermoplastic resin composition A and the thermoplastic resin composition B are common, which tends to further improve the bonding strength between the member 1 and the member 2. In addition, in this embodiment, it is preferable that 70% by mass of the composition of the thermoplastic resin composition A and the thermoplastic resin composition B is common, more preferably 80% by mass or more, and even more preferably 85% by mass or more. In this way, by having a common composition between the thermoplastic resin composition A and the thermoplastic resin composition B, the molding shrinkage rate and the like tend to be the same, and the bonding strength over time can be more effectively maintained at a high level.

[0093] <Method for Producing Thermoplastic Resin Compositions> Thermoplastic resin composition A and thermoplastic resin composition B can each be produced by a conventional method for preparing a resin composition. Typically, the components and various optional additives are thoroughly mixed together and then melt-kneaded in a single-screw or twin-screw extruder. Alternatively, thermoplastic resin composition A and thermoplastic resin composition B can be prepared by premixing the components, or by premixing only a portion of the components, feeding the mixture into an extruder using a feeder, and melt-kneading the mixture. As described above, some components, such as conductive compounds and optically transparent dyes, may be melt-kneaded with a thermoplastic resin to prepare a masterbatch, which may then be blended with the remaining components and melt-kneaded. When using a reinforcing material such as glass fiber, it is also preferable to feed the masterbatch from a side feeder midway through the extruder cylinder. The heating temperature during melt-kneading can usually be selected appropriately from a range of 220 to 300°C. If the temperature is too high, decomposition gases are likely to be generated, which may cause opacity. Therefore, it is desirable to select a screw configuration that takes shear heat generation, etc. into consideration. To prevent decomposition during kneading and subsequent molding, it is desirable to use an antioxidant or a heat stabilizer.

[0094] <Method for manufacturing the first member and the second member> The method for manufacturing the first member and the second member is not particularly limited, and any molding method commonly used for resin compositions can be used. Examples include injection molding, ultra-high speed injection molding, injection compression molding, two-color molding, gas-assisted hollow molding, molding using an insulated mold, molding using a rapidly heated mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding), extrusion molding, sheet molding, thermoforming, rotational molding, lamination molding, press molding, blow molding, etc., among which injection molding is preferred. For details of injection molding, please refer to the descriptions in paragraphs 0113 to 0116 of Japanese Patent No. 6183822, the contents of which are incorporated herein by reference.

[0095] <Structure and Manufacturing Method Thereof> In the structure of this embodiment, the first member and the second member are at least partially bonded, and typically only partially bonded. The bonding in this embodiment includes a mode in which at least a portion of the surface of the first member and at least a portion of the surface of the second member are in direct contact with each other or via an adhesive, thereby integrating the two members. A preferred mode is a mode in which at least a portion of the surface of the first member and at least a portion of the surface of the second member are in direct contact with each other, thereby integrating the two members. More specifically, the first member and the second member are preferably bonded by any of laser welding, vibration welding, ultrasonic welding, two-color molding, insert molding, screwing, adhesive bonding, and fitting, more preferably by laser welding, vibration welding, ultrasonic welding, or adhesive bonding, even more preferably by laser welding, vibration welding, or ultrasonic welding, and even more preferably by laser welding. In this embodiment, in particular, the first member and the second member are joined by laser welding, and it is preferable that the first member be on the laser transmission side during laser welding. That is, it is preferable that the second member be on the laser absorption side. Therefore, the structure of this embodiment includes at least a partial joining of a first member formed from a thermoplastic resin composition A and a second member formed from a thermoplastic resin composition B. Here, the thermoplastic resin composition A has a transmittance of 70% or more at a frequency of 76.5 GHz, as determined according to formula (C), for a test piece molded to a thickness of 2 mm. The thermoplastic resin composition B has a transmittance of less than 50% at a frequency of 76.5 GHz, as determined according to formula (C), and an absorptance of 40% or more at a frequency of 76.5 GHz, as determined according to formula (A).

[0096] Next, a laser welding method will be described. In this embodiment, a structure can be manufactured by laser welding a first member and a second member. Laser welding allows the first member and the second member to be firmly welded without using an adhesive. The shape of the members is not particularly limited, but since the members are joined together by laser welding, it is usually preferable that the shape has at least a surface contact area (flat surface, curved surface). In laser welding, for example, laser light transmitted through the first member is absorbed by the second member, melts the second member, and the two members are welded together. Here, the thickness of the first member through which the laser light transmits (the thickness in the laser transmission direction at the portion through which the laser light transmits) can be appropriately determined taking into consideration the application and other factors, but the thickest portion is, for example, 5 mm or less, preferably 4 mm or less. The lower limit of the thinnest portion is 0.1 mm or more.

[0097] The laser light source used for laser welding can be determined based on the absorption wavelength of the light of the light-absorbing dye. A laser with a wavelength in the range of 900 to 1100 nm is preferred, and for example, a semiconductor laser or fiber laser can be used. In this embodiment, galvano scanning laser welding is more preferred. Galvano scanning laser welding, also known as galvano laser welding or quasi-simultaneous welding, is a method in which a laser beam is scanned using a built-in galvanometer mirror. The use of galvano scanning laser welding enables laser welding over a wide range, facilitating laser welding of uneven materials and materials with different thicknesses. In galvano scanning laser welding, the laser irradiation speed is preferably 500 to 1500 mm / s, and the number of laser irradiation cycles is preferably 3 to 30 cycles.

[0098] More specifically, the following description will be given taking, as an example, the welding of a first member as a transmission-side member and a second member as an absorption-side member. First, the welding points of the two members are brought into contact with each other. Surface contact between the two welding points is desirable, and they may be flat surfaces, curved surfaces, or a combination of flat and curved surfaces. Next, laser light is irradiated from the first member side (laser transmission side). If necessary, a lens may be used to focus the laser light at the interface between the two members. The focused beam passes through the transmission-side resin member and is absorbed near the surface of the absorption-side resin member, generating heat and melting it. The heat is then transferred by thermal conduction to the transmission-side resin member, melting it and forming a molten pool at the interface between the two members. After cooling, the two members are joined. A structure formed by welding the first member and the second member in this manner has high welding strength. Note that the term "structure" in this embodiment encompasses not only finished products and parts, but also components that form part of these.

[0099] The first and second members in the structure can have a laser welding strength of 800 MPa or more, and can further be 1000 MPa or more, or 1300 MPa or more. The upper limit of the laser welding strength is not particularly specified, but 3000 MPa or less is practical. The laser welding strength is measured according to the description in the examples below.

[0100] The present invention will be explained in more detail below with reference to examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or the like, measurements can be made using other instruments with equivalent performance.

[0101] 1. Raw Materials <First Member (Thermoplastic Resin Composition A)> The following raw materials were used: In Table 1 below, PBT means polybutylene terephthalate resin (the same applies to the following tables). Novaduran is a resin composition pellet containing glass fiber, a release agent, and other ingredients.

[0102] <Second member (thermoplastic resin composition B)> The following raw materials were used: In Table 2 below, HIPS stands for high impact polystyrene, and CNT stands for carbon nanotubes (the same applies to the following tables).

[0103]

[0104] For the materials shown in Table 2, the components other than the glass fiber (GF) were placed in a stainless steel tumbler as shown in Table 3 and mixed by stirring for 1 hour. Each component in Table 3 is expressed in parts by mass. The resulting mixture was placed in the main hopper of a 30 mm vent-type twin-screw extruder (manufactured by The Japan Steel Works, Ltd., "TEX30α"), and the glass fiber (GF) was fed from the seventh side feeder from the hopper. The mixture was kneaded and extruded into strands under the following conditions: extruder barrel temperatures C1 to C15 were set to 260°C, the die was set to 250°C, the screw rotation speed was 200 rpm, and the output rate was 40 kg / hour, to obtain pellets of thermoplastic resin composition B.

[0105] 2. Absorption, Reflectance, and Transmittance at a Frequency of 76.5 GHz Pellets of thermoplastic resin composition A and pellets of thermoplastic resin composition B were injection molded using an injection molding machine ("NEX80" manufactured by Nissei Plastic Industrial Co., Ltd.) with a cylinder setting temperature of 260°C and a mold temperature of 80°C, to obtain test pieces of 100 mm x 100 mm x 2 mm thickness and 100 mm x 100 mm x 3 mm thickness. Using the obtained test pieces, the absorption calculated according to formula (A), the reflectance calculated according to formula (B), and the transmittance calculated according to formula (C) at a frequency of 76.5 GHz were measured as follows. For the measurements, a network analyzer "N5252A" manufactured by Keysight Corporation was used. The test pieces were placed so that the TD (flow direction) of the injection molded article was parallel to the electric field direction. Formula (A) (In the above formula (A), R represents the return loss measured by the free space method, and T represents the transmission loss measured by the free space method.)

[0106] Formula (B) (In the above formula (B), R represents the return loss measured by the free space method.)

[0107] Formula (C) (In the above formula (C), T represents the transmission attenuation measured by the free space method.)

[0108]

[0109] 3. Examples 1 to 10 (Laser Welding) <Molding of First Member (Thermoplastic Resin Composition A)> The resin pellets were dried at 120°C for 7 hours and then molded using an injection molding machine ("J55" manufactured by The Japan Steel Works, Ltd.) at a cylinder temperature of 260°C and a mold temperature of 60°C to produce a molded body (transparent resin member I) having a thickness of 1.5 mm as shown in FIG.

[0110] <Molding of second member (thermoplastic resin composition B)> The resin pellets obtained above were dried at 120°C for 7 hours, and then molded using an injection molding machine ("J55" manufactured by The Japan Steel Works, Ltd.) at a cylinder temperature of 260°C and a mold temperature of 60°C to produce a molded body (absorbent resin member II) as shown in Figure 7.

[0111] The first and second members shown in Tables 4 and 5 were selected, and holes 21 and 22 were drilled in each as shown in Figures 8 and 9. Welding strength measurement jigs 23 and 24 were placed inside the holes. Then, a lid-shaped transmissive resin member I was placed on a box-shaped absorbing resin member II. A laser light source was positioned vertically above the flange, which was the overlapping portion of the transmissive resin member I and the absorbing resin member II. A laser was irradiated under the conditions shown in Tables 4 and 5 while applying a pressure of 4.92 N / mm (pressure during welding) inward from both sides in the thickness direction to the overlapping portion of the transmissive resin member I and the absorbing resin member II using a glass plate, thereby obtaining a laser-welded body. The portion marked X in Figure 8 is the portion irradiated with the laser. The welding apparatus is as follows.

[0112] <Galvano scanning laser welding> Laser device: YLR-300-AC-Y14 manufactured by IPG Wavelength: 1070 nm Collimator: 7.5 mm Laser type: Fiber Laser intensity (output): 180 W Galvano scanner: Fiber Elephant's 21 manufactured by ARGES Aperture: 21 mm Laser irradiation speed: 900 mm / s Laser irradiation cycles: as shown in Table 4 or Table 5 Circumference of welded part: 137 mm The laser light was defocused and the position of the laser scanner was adjusted so that the spot diameter irradiated on the welded surface was 2 mm in diameter.

[0113] <Laser welding strength> As shown in Figure 9, measuring jigs 25 and 26 were inserted into the top and bottom of a box made of the transparent resin member I and the absorbing resin member II prepared above, respectively, and connected to the jigs 23 and 24 stored inside. The box was then pulled up and down (tensile speed: 5 mm / min) to measure the strength (welding strength, unit: MPa) at which the transparent resin member I and the absorbing resin member II separated. The testing device used was a 1t Tensilon universal testing machine (load cell 10 kN) manufactured by ORIENTEC. The results are shown in Tables 4 and 5 below.

[0114] As is clear from the above results, in the present invention, the first member and the second member were appropriately laser welded together.

[0115] 4. Example 11 (Two-Color Molding) The resin pellets were dried at 120°C for 7 hours and then molded using an injection molding machine (Japan Steel Works, Ltd., "J180") at a first cylinder temperature of 260°C, a second cylinder temperature of 260°C, and a mold temperature of 80°C to produce 5 mm-thick dumbbell-shaped test specimens as shown in Figure 10. In Figure 10, (a) shows a schematic diagram of the entire dumbbell test specimen, and (b) is an enlarged explanatory view of the circled portion in (a), showing a cross-sectional view of (a) in the flow direction. In (b) of Figure 10, 31 indicates thermoplastic resin composition A and 32 indicates thermoplastic resin composition B. Specifically, thermoplastic resin composition A was filled from the first cylinder from the gate on the side of the dumbbell-shaped test specimen to the center, and then thermoplastic resin composition B was filled from the gate on the opposite side of the dumbbell-shaped test specimen. The dumbbell-shaped test specimen was molded so that a resin-bonded portion was formed at the center. At this time, the thermoplastic resin composition A was filled so as to be tilted approximately 5°C toward the flow direction. The tensile breaking stress of the two-color molded dumbbell-shaped test pieces obtained above was measured using a universal testing machine (Tensilon RTF2350 manufactured by A&D Co., Ltd.). The results are shown in Table 6 below.

[0116]

[0117] REFERENCE SIGNS LIST 1 First member 2 Second member 3 Element 21, 22 Hole 23, 24 Measuring jig 25, 26 Measuring jig 31 Thermoplastic resin composition A 32 Thermoplastic resin composition B

Claims

1. A first member formed from a thermoplastic resin composition A and a second member formed from a thermoplastic resin composition B, The first member and the second member are at least partially joined together, The thermoplastic resin composition A has a transmittance of 70.0% or more at a frequency of 76.5 GHz, the transmittance being calculated according to formula (C) of a test piece having a thickness of 2 mm, The thermoplastic resin composition B has a transmittance of less than 50.0% at a frequency of 76.5 GHz, as determined according to formula (C), for a test piece molded to a thickness of 2 mm. The thermoplastic resin composition B has an absorbance of 40.0% or more at a frequency of 76.5 GHz, the absorbance being calculated according to formula (A) of a test piece molded to a thickness of 2 mm. structure. Formula (C) [0010] (In the above formula (C), T represents the transmission attenuation measured by the free space method.) Formula (A) [0025] (In the above formula (A), R represents the return loss measured by the free space method, and T represents the transmission loss measured by the free space method.)

2. 2. The structure of claim 1, wherein said thermoplastic resin composition B comprises a conductive carbon compound.

3. The structure of claim 2 , wherein the conductive carbon compound comprises carbon nanotubes.

4. 2. The structure of claim 1, wherein said thermoplastic resin composition B comprises a reinforcement material.

5. 2. The structure of claim 1, wherein said thermoplastic resin composition B comprises a polybutylene terephthalate resin.

6. The structure of claim 1 , wherein the thermoplastic resin composition A comprises a polybutylene terephthalate resin.

7. 2. The structure according to claim 1, wherein the first member and the second member are joined by any one of laser welding, vibration welding, ultrasonic welding, two-color molding, insert molding, screwing, adhesion with an adhesive, and fitting.

8. The first member and the second member are joined by laser welding, The structure according to claim 1 , wherein the first member is a laser transmitting side during laser welding.

9. 2. The structure according to claim 1, wherein the difference between the absorption rate of a test piece obtained by molding the thermoplastic resin composition A to a thickness of 2 mm at a frequency of 76.5 GHz according to formula (A) and the absorption rate of a test piece obtained by molding the thermoplastic resin composition B to a thickness of 2 mm at a frequency of 76.5 GHz according to formula (A) is 40.0% or more.

10. The structure of claim 1 including an electromagnetic wave control.

11. The structure according to claim 1 , further comprising a housing having a hollow structure surrounded by at least the first member and the second member, the housing containing an element.

12. 12. The structure of claim 11, wherein the element is an element that transmits and / or detects electromagnetic waves, and at least one type of the electromagnetic waves is transmitted through the first member and at least one type of the electromagnetic waves is absorbed by the second member.

13. 13. The structure of claim 12, wherein the first member and / or the second member are present in any direction opposite to the direction in which the electromagnetic waves are emitted and / or detected.

14. The thermoplastic resin composition B contains a conductive carbon compound, the conductive carbon compound comprises carbon nanotubes; The thermoplastic resin composition B includes a reinforcing material, The thermoplastic resin composition B contains a polybutylene terephthalate resin, The thermoplastic resin composition A contains a polybutylene terephthalate resin, the first member and the second member are joined by any one of laser welding, vibration welding, ultrasonic welding, two-color molding, insert molding, screw fastening, adhesion with an adhesive, and fitting; The first member and the second member are joined by laser welding, the first member is a laser transmitting side during laser welding, the difference between the absorptance, determined according to formula (A) at a frequency of 76.5 GHz, of a test piece obtained by molding the thermoplastic resin composition A to a thickness of 2 mm, and the absorptance, determined according to formula (A) at a frequency of 76.5 GHz, of a test piece obtained by molding the thermoplastic resin composition B to a thickness of 2 mm, is 40.0% or more; An electromagnetic wave control body is included, the structure has at least a housing having a hollow structure surrounded by the first member and the second member, the housing containing an element, the element is an element that transmits and / or detects electromagnetic waves, at least one type of the electromagnetic waves is transmitted through the first member, and at least one type of the electromagnetic waves is absorbed by the second member; 2. The structure of claim 1, wherein the first member and / or the second member are present in any direction opposite to the direction in which the electromagnetic waves are emitted and / or detected.

15. A first member formed from a thermoplastic resin composition A; and at least a portion of the second member formed from the thermoplastic resin composition B, The thermoplastic resin composition A has a transmittance of 70.0% or more at a frequency of 76.5 GHz, the transmittance being calculated according to formula (C) of a test piece having a thickness of 2 mm, The thermoplastic resin composition B has a transmittance of less than 50.0% at a frequency of 76.5 GHz, as determined according to formula (C), for a test piece molded to a thickness of 2 mm. The thermoplastic resin composition B has an absorbance of 40.0% or more at a frequency of 76.5 GHz, the absorbance being calculated according to formula (A) of a test piece molded to a thickness of 2 mm. A method for manufacturing a structure. Formula (C) [0030] (In the above formula (C), T represents the transmission attenuation measured by the free space method.) Formula (A) [0045] (In the above formula (A), R represents the return loss measured by the free space method, and T represents the transmission loss measured by the free space method.)

16. A millimeter wave radar module comprising the structure according to any one of claims 1 to 14.

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