Composite molded article and resin composition

Abstract

The present invention provides: a composite molded article which is capable of securing sufficient airtightness not only at the initial stage but also after a heat shock test; and a resin composition which enables the achievement of such a composite molded article. According to one embodiment of the present invention, there is provided a composite molded article 10 which includes: a member 20; and a resin molded article 30 that is joined to the member 20. The member 20 has a surface roughened part 21, which has a recessed part 21A, in at least a part of a surface 20A of the member 20. The resin molded article 30 includes: a resin 31 that enters at least the recessed part 21A; and a stretched elastomer 32 that is present in the resin 31 and has an aspect ratio, which is the ratio of the major axis to the minor axis, of 1.5 or more in a cross section when the composite molded article 10 is cut in the thickness direction of the resin molded article 30. At least a part of the stretched elastomer 32 is located in the recessed part 21A in the cross section, and is present along the interface IF of the member 20 and the resin molded article 30 in a recessed part interface region R that extends along the interface IF.

Description

Composite molded article and resin composition REFERENCE TO RELATED APPLICATIONS

[0001] This application benefits from the priority of an earlier Japanese application, Patent Application No. 2024-4923 (filing date: January 16, 2024), the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a composite molded article and a resin composition.

[0003] By combining materials with different properties, such as electrically conductive materials such as metals and electrically insulating materials such as resins, lightweight, strong, or highly functional parts are being used in a variety of fields. For example, metal-resin composite molded products, in which a metal member is bonded to a thermoplastic resin, are used in automobile interior components such as console boxes around instrument panels, engine-related components, interior parts, housings, interface connections, and power terminals for electronic devices such as digital cameras and mobile phones.

[0004] Generally, bonding and screwing are known as methods for joining different materials, such as metal and resin, but these methods are not desirable because they increase the number of processes and parts required. Therefore, various methods have been proposed for joining components made of metal materials and resin materials.

[0005] For example, Patent Document 1 describes laser processing of the surface of a metal material in one scanning direction, followed by laser processing in another scanning direction intersecting the scanning direction, and then joining a different material to the surface. Patent Document 2 describes improving the joining strength when joining a resin molded product to the surface by forming irregularities on the surface of a metal plate and maintaining an undercut rate of the irregularities within a predetermined range. Patent Document 3 describes a metal-resin composite molded product in which crater-like depressions are formed in the metal using laser light or the like, and granular spatter is formed on the ridge-like protrusions where the metal surface is melted and scattered. Patent Document 4 describes a composite structure formed by joining a surface-roughened metal member and a polyarylene sulfide resin composition member, in which the number-average developed area ratio (Sdr) of the interface is in the range of 5 or more when any five points on the surface of the surface-roughened metal member are measured using a confocal microscope in accordance with ISO (International Organization for Standardization) 25178, and the melt viscosity of the PPS resin is in the range of 15 to 500 [Pa s]. Furthermore, Patent Document 5 discloses a metal insert part and a method for manufacturing a resin molded product using a metal insert part, with the aim of performing insert molding using a resin material and a metal material that ensures airtightness and excellent durability.

[0006] Japanese Patent No. 4020957 Japanese Patent Application Laid-Open No. 2020-116806 Japanese Patent Application Laid-Open No. 2013-71312 Japanese Patent No. 6819798 Japanese Patent No. 6615478

[0007] However, conventional methods for joining components made of metal or other materials with resin materials fail to ensure sufficient airtightness at the joint between the components and the resin material (i.e., problems such as the formation of gaps at the joint between the components and the resin material can occur), and improvements in this area are needed. Furthermore, when composite molded products are used in environments with large temperature changes, such as in automobile engine peripherals, the following problems can arise due to the extremely different expansion and contraction rates (so-called linear expansion coefficients) of resin and metal with temperature changes. For example, when the resin component of a metal-resin composite molded product is thin or has portions with large thickness variations, or when the metal component has sharp corners, the metal-resin composite molded product can break due to temperature changes during use. For this reason, the applications and shapes of metal-resin composite molded products are currently quite limited. Therefore, there is a strong demand for composite molded products that can withstand temperature changes over long periods of time.

[0008] The present invention has been made to solve the above problems, and an object of the present invention is to provide a composite molded article that can ensure sufficient airtightness not only initially but also after a heat shock test, and a resin composition from which such a composite molded article can be obtained.

[0009] [1] A composite molded product comprising a member and a resin molded product joined to the member, wherein the member has a surface roughened portion having recesses on at least a portion of the surface of the member, and the resin molded product contains a resin that has entered at least the recesses and an expanded elastomer that is present in the resin and has an aspect ratio, which is the ratio of the major axis to the minor axis, of 1.5 or more in a cross section when the composite molded product is cut in the thickness direction of the resin molded product, and at least a portion of the expanded elastomer is located within the recesses and present along the interface between the member and the resin molded product in a recess interface region that is along the interface.

[0010] [2] The composite molded article according to the above [1], wherein the stretched elastomer is a reactive elastomer, and the reactive elastomer has a glycidyl group.

[0011] [3] The composite molded article according to the above [1] or [2], wherein the resin is composed of a polyarylene sulfide-based resin composition, and the melt viscosity of the polyarylene sulfide-based resin composition is 10 Pa·s or more and 350 Pa·s or less.

[0012] [4] The composite molded product according to [1] or [2] above, wherein the resin is composed of a polybutylene terephthalate-based resin composition, and the melt viscosity of the polybutylene terephthalate-based resin composition is 50 Pa·s or more and 300 Pa·s or less.

[0013] [5] The composite molded product according to any one of [1] to [4] above, wherein the member is a metal member and the roughened surface portion is a metal cluster.

[0014] [6] A resin composition used in the production of the composite molded product according to any one of [1] to [5] above, comprising a resin and an elastomer having an aspect ratio, which is the ratio of the major axis to the minor axis, of 1 or more and less than 1.5, wherein when the resin composition is molded at a molding temperature equal to or higher than the melting point of the elastomer so as to fill a recess in a member having a roughened surface portion having a recess on at least a part of its surface, the elastomer stretches in a recess interface region located within the recess and along the interface between the member and the resin composition, forming a stretched elastomer having an aspect ratio of 1.5 or more along the interface.

[0015] According to one aspect of the present invention, it is possible to provide a composite molded article that can ensure sufficient airtightness not only initially but also after a heat shock test, and a resin composition that can be used to obtain such a composite molded article.

[0016] FIG. 1A is a plan view of a composite molded product according to an embodiment, and FIG. 1B is a side view of the composite molded product according to an embodiment. FIG. 2 is an enlarged cross-sectional view of a portion of the composite molded product shown in FIG. 1 when the composite molded product is cut in the thickness direction of the composite molded product. FIG. 3A is a plan view of the member shown in FIG. 1, and FIG. 3B is a side view of the member shown in FIG. 1. FIG. 4 is a diagram schematically illustrating the state of the interface between the member and the resin molded product depending on the size of the SPC on the surface of the member in the composite molded product. FIG. 5A is a plan view of a composite molded product according to Example 4, and FIG. 5B is a cross-sectional view taken along the X-X line of FIG. 5A. FIG. 6 is a schematic diagram of a testing device used in an airtightness test. FIG. 7 is a scanning electron microscope photograph of a cross section of the composite molded product according to Example 4 when cut in the thickness direction of the composite molded product. FIG. 8 is a scanning electron microscope photograph of a cross section of the composite molded product according to Comparative Example 2 when cut in the thickness direction of the composite molded product. 9A to 9E are diagrams schematically showing the manufacturing process of the test pieces according to Reference Examples 1 to 5.

[0017] Hereinafter, a composite molded article and a resin composition according to an embodiment of the present invention will be described. Fig. 1A is a plan view of a composite molded article according to this embodiment, Fig. 1B is a side view of the composite molded article according to this embodiment, and Fig. 2 is an enlarged cross-sectional view of a portion of the composite molded article shown in Fig. 1 when the composite molded article is cut in the thickness direction of the composite molded article. Fig. 3A is a plan view of the member shown in Fig. 1, and Fig. 3B is a side view of the member shown in Fig. 1. Fig. 4 is a diagram schematically illustrating the state of the interface between the member and the resin molded article depending on the size of the Spc on the surface of the member in the composite molded article.

[0018] <<<<Composite Molded Product>>> The composite molded product 10 shown in Fig. 1 includes a member 20 and a resin molded product 30 joined to the member 20. The composite molded product 10 shown in Fig. 1 is a bus bar. Note that the composite molded product is not limited to bus bars and can be used for a variety of purposes. For example, the composite molded product may be an automobile interior component such as a console box around the instrument panel, an engine-related component, an interior component, a housing, an interface connection, or a power terminal of an electronic device such as a digital camera or a mobile phone.

[0019] <<Member>> The member 20 has a roughened surface portion 21 (see FIGS. 2, 3A, and 3B) having recesses 21A in at least a part of a surface 20A of the member 20, and two through-hole portions 22 (see FIGS. 1A and 3A) that penetrate the member 20 in the thickness direction. Note that the member 20 does not need to have the through-hole portions 22 as long as it has the roughened surface portion 21. The roughened surface portion 21 has an uneven shape, and a resin 31, which will be described later, fills the recesses 21A present in the roughened surface portion 21, as shown in FIG. 2.

[0020] The entrance width W (see FIG. 2 ) of the recess 21A is not particularly limited, but is preferably, for example, 5 nm to 1000 μm, more preferably 10 μm to 100 μm, and particularly preferably 30 μm to 50 μm. The depth D (see FIG. 2 ) of the recess 21A is not particularly limited, but is, for example, preferably 10 nm to 1000 μm, more preferably 1 μm to 100 μm, and particularly preferably 1 μm to 10 μm.

[0021] Since the roughened surface portion 21 has an uneven shape, it has not only recesses 21A but also protrusions 21B. The recesses 21A are provided between the protrusions 21B. In FIG. 2 , the recesses 21A refer to the region sandwiched between the surface of the roughened surface portion 21 and an imaginary line (broken line) connecting the tops of the protrusions 21B. The roughened surface portion 21 can be formed using a conventionally known method, such as a method of chemically or mechanically roughening the surface of the member 20. Specific examples of the method include a method of forming metal clusters by laser irradiation, a blasting method such as sandblasting or shot blasting, an etching method, an immersion method in an aggressive aqueous solution or suspension, and an anodization method.

[0022] The arithmetic mean curvature (Spc) of the peaks in the roughened surface portion 21 is preferably 2000 (1 / mm) or more and 4500 (1 / mm) or less. Spc is a surface texture parameter defined in ISO 25178, and represents the average value of the principal curvatures of the peaks formed on the surface to be evaluated. A small Spc indicates that the point of contact with the resin molded product (peak) is rounded, while a large Spc indicates that the point of contact with the resin molded product is sharp.

[0023] If the Spc of the roughened surface portion 21 is within the above range, the occurrence of gaps between the member 20 and the resin molded product 30 can be further suppressed, thereby ensuring sufficient airtightness not only initially but also after a heat shock test. This is presumed as follows. Figures 4A to 4C schematically show the bonding surface between the member 40 and the resin molded product 50 when the Spc of the peaks of the roughened surface portion 41 formed on the surface 40A of the member 40 is large ("large Spc"), medium ("medium Spc"), and small ("small Spc"). When the Spc of the roughened surface portion 41 of the member 40 is large (see Figure 4A), the peaks of the roughened surface portion 41 have a sharp shape. When the resin composition in contact with the roughened surface portion 41 cools, a sink mark (shrinkage) 51 occurs. However, if the peaks of the roughened surface portion 41 are sharp, gaps are likely to form between the resin composition and the member 40 at the joint surface of the peaks, which is disadvantageous in terms of achieving high airtightness. On the other hand, when the Spc of the roughened surface portion 41 is small (see FIG. 4C), the roughened surface portion 41 has a surface texture that changes gradually overall. The surface area of ​​the joint between the member 40 and the resin molded product 50 is small, making it difficult to achieve high adhesion between the member 40 and the resin molded product 50 during the molding stage of the composite molded product. In contrast, when the Spc of the roughened surface portion 41 is moderate ( FIG. 4B ), the molten resin composition penetrates the roughened surface portion 41 sufficiently, and the recesses 41A formed in the roughened surface portion 41 can form many anchors with the resin molded product 50. For these reasons, if the Spc of the surface roughened portion 21 is within the above range, loosening (leak paths) of the joint due to the expansion and contraction of the resin constituting the resin molded product that occurs during the heat shock test is less likely to form, and it is therefore presumed that the adhesion between the member 20 of the composite molded product 10 and the resin molded product 30 can be maintained extremely high even after the heat shock test.

[0024] The lower limit of the Spc of the roughened surface portion 21 is preferably 2100 (1 / mm) or more, or 2200 (1 / mm) or more. The upper limit of the Spc of the roughened surface portion 21 is preferably 4000 (1 / mm) or less, 3500 (1 / mm) or less, or 3000 (1 / mm) or less. For example, the Spc of the roughened surface portion 21 is more preferably 2000 (1 / mm) or more to 4000 (1 / mm) or less, 2100 (1 / mm) or more to 4000 (1 / mm) or less, 2100 (1 / mm) or more to 2800 (1 / mm) or less, or 2200 (1 / mm) or more to 2800 (1 / mm) or less.

[0025] The Spc of the roughened surface portion 21 is measured using a laser microscope (Keyence's "VK-X3000"). When measuring the Spc of the roughened surface portion 21 of the composite molded product 10, first, the resin molded product 30 on the roughened surface portion 21 is removed using a chemical or the like, and the Spc is measured with the surface of the roughened surface portion 21 exposed.

[0026] When the member 20 is a metal member and the protrusions 21B are composed of metal clusters, the Spc can be adjusted to fall within a desired range by controlling the energy applied by laser irradiation to the surface that will become the joining surface between the metal member and the resin molded product. When a pulsed laser is used as the laser, the energy per pulse E is expressed as P / f, where P is the average output and f is the frequency. Therefore, by adjusting the average output P (i.e., laser output) and / or the frequency f, the energy applied to the surface that will become the joining surface between the member and the resin molded product can be controlled. For example, increasing the frequency of the pulsed laser reduces the amount of energy per pulse applied to the surface of the metal member, which tends to decrease the Spc. Conversely, decreasing the frequency of the pulsed laser increases the amount of energy per pulse applied to the surface of the metal member, which tends to increase the Spc. However, once the amount of energy becomes sufficiently large, the Spc saturates.

[0027] The particle size of the particles constituting the metal clusters is preferably 1 μm or more and 500 μm or less, more preferably 5 μm or more and 300 μm or less, and particularly preferably 10 μm or more and 200 μm or less. If the particle size is 1 μm or more, the resin fills the recesses that are the gaps between the particles constituting the metal clusters, and adhesion can be further improved. On the other hand, if the particle size is 500 μm or less, gaps with the metal member are less likely to occur due to shrinkage of the resin after molding, and airtightness can be more sufficiently ensured.

[0028] The constituent material of the member 20 is not particularly limited, but examples thereof include metal, resin, ceramic, etc. Examples of metal include aluminum, copper, silver, gold, iron, titanium, nickel, magnesium, zinc, and alloys thereof such as carbon steel and stainless steel.

[0029] Furthermore, when the constituent material of the member 20 is a metal, the surface 20A of the member 20 may be subjected to a surface treatment such as anodizing or may be painted. From the viewpoints of light weight and strength, it is preferable to use aluminum, magnesium, copper, or titanium as the metal, and in applications requiring conductivity such as terminals, it is more preferable to use aluminum or copper, with copper being particularly preferred. Furthermore, in applications requiring rigidity in a thin wall, it is particularly preferable to use magnesium or titanium, and titanium in particular.

[0030] <<Resin Molded Article>> The resin molded article 30 includes at least a resin 31 that has filled the recesses 21A present in the roughened surface portion 21, and an expanded elastomer 32 that is present in the resin 31 and has an aspect ratio (major axis / minor axis) of 1.5 or more, which is the ratio of the major axis to the minor axis. In addition to the resin 31 and the expanded elastomer 32, the resin molded article 30 may also include an elastomer 33 that has an aspect ratio of 1 or more and less than 1.5, an inorganic filler, and / or an additive.

[0031] 1A and 1B covers a portion of the member 20. The resin molded product 30 has a disk portion 30A, an annular portion 30B adjacent to the disk portion 30A and having a smaller outer diameter than the disk portion 30A, and flat portions 30C located on both outer sides of the disk portion 30A in the longitudinal direction of the member 20 and adjacent to the disk portion 30A.

[0032] <Resin> The resin 31 is not particularly limited, and for example, a thermoplastic resin can be used. Examples of thermoplastic resins include polyolefin-based resins such as polypropylene resin, polyethylene resin, poly(1-)butene resin, and polypentene resin; polyester-based resins such as polybutylene terephthalate resin (PBT), polyethylene terephthalate resin (PET), and polytrimethylene terephthalate resin (PTT); polyacetal-based resins; polyarylene sulfide-based resins such as polyphenylene sulfide resin; and polyamide-based resins. The resin also includes a resin mixture obtained by blending multiple resins. Polyarylene sulfide-based resins are characterized by excellent mechanical properties, electrical properties, heat resistance, and other physical and chemical properties, as well as good processability.

[0033] (Polyarylene sulfide resin) A polyarylene sulfide resin is a polymer compound mainly composed of a repeating unit -(Ar-S)- (where Ar is an arylene group), and in this embodiment, a polyarylene sulfide resin having a generally known molecular structure can be used.

[0034] Examples of the arylene group include a p-phenylene group, an m-phenylene group, an o-phenylene group, a substituted phenylene group, a p,p'-diphenylenesulfone group, a p,p'-biphenylene group, a p,p'-diphenylene ether group, a p,p'-diphenylenecarbonyl group, a naphthalene group, etc. The PAS resin may be a homopolymer consisting of only the above repeating units, or a copolymer containing the following different repeating units may be preferred in terms of processability, etc.

[0035] As a homopolymer, a polyphenylene sulfide resin (also referred to as a PAS resin) having a p-phenylene sulfide group as a repeating unit, in which a p-phenylene group is used as the arylene group, is preferably used. Furthermore, as a copolymer, a combination of two or more different arylene sulfide groups composed of the above-mentioned arylene groups can be used, and a combination containing a p-phenylene sulfide group and an m-phenylene sulfide group is particularly preferred. Among these, a copolymer containing 70 mol % or more, preferably 80 mol % or more, of p-phenylene sulfide groups is suitable from the viewpoint of physical properties such as heat resistance, moldability, and mechanical properties.

[0036] Among these PAS resins, a high molecular weight polymer having a substantially linear structure obtained by condensation polymerization of a monomer mainly composed of a bifunctional halogenated aromatic compound is particularly preferred. The polyarylene sulfide resin used in this embodiment may be a mixture of two or more polyphenylene sulfide resins having different molecular weights.

[0037] In addition to the linear polyphenylene sulfide resin, examples of the polymer include a polymer in which a partially branched structure or a crosslinked structure is formed by using a small amount of a monomer such as a polyhaloaromatic compound having three or more halogen substituents during condensation polymerization, and a polymer in which the melt viscosity is increased by oxidative crosslinking or thermal crosslinking by heating a low-molecular-weight linear polymer at a high temperature in the presence of oxygen or the like, thereby improving moldability.

[0038] (Polybutylene terephthalate-based resin) Polybutylene terephthalate-based resin (PBT-based resin) contains at least terephthalic acid or its ester-forming derivative (C １－６ It is a resin obtained by polycondensation of a dicarboxylic acid component containing an alkylene glycol (such as an alkyl ester or acid halide of 1,4-butanediol) having at least 4 carbon atoms, and a glycol component containing an alkylene glycol (1,4-butanediol) or an ester-forming derivative thereof (such as an acetylated product). The PBT resin is not limited to homopolybutylene terephthalate, but may also be a copolymer containing 60 mol % or more (particularly 75 mol % to 95 mol %) of butylene terephthalate units.

[0039] The amount of terminal carboxyl groups in the PBT resin is not particularly limited, but is, for example, preferably 30 meq / kg or less, more preferably 25 meq / kg or less.

[0040] In the PBT resin, examples of dicarboxylic acid components (comonomer components) other than terephthalic acid and its ester-forming derivatives include C terephthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-dicarboxydiphenyl ether, etc. ８－１４ aromatic dicarboxylic acids of C, such as succinic acid, adipic acid, azelaic acid, and sebacic acid; ４－１６ alkanedicarboxylic acids such as cyclohexanedicarboxylic acid; ５－１０ cycloalkanedicarboxylic acids of the formula (C); ester-forming derivatives of these dicarboxylic acid components (C １－６ These dicarboxylic acid components may be used alone or in combination of two or more.

[0041] Among these dicarboxylic acid components, C ８－１２ Aromatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid ６－１２ The alkanedicarboxylic acids are more preferred.

[0042] In the PBT resin, examples of glycol components (comonomer components) other than 1,4-butanediol include C glycols such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, and 1,3-octanediol. ２－１０ alkylene glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, and the like; alicyclic diols such as cyclohexanedimethanol and hydrogenated bisphenol A, and the like; aromatic diols such as bisphenol A and 4,4'-dihydroxybiphenyl, and the like; C-type alkylene glycols of bisphenol A such as ethylene oxide 2-mol adduct of bisphenol A and propylene oxide 3-mol adduct of bisphenol A, and the like; ２－４or ester-forming derivatives of these glycols (acetylated products, etc.). These glycol components can be used alone or in combination of two or more.

[0043] Among these glycol components, C ethylene glycol, trimethylene glycol, etc. ２－６ More preferred are alkylene glycols such as those listed above, polyoxyalkylene glycols such as diethylene glycol, and alicyclic diols such as cyclohexanedimethanol.

[0044] Examples of comonomer components that can be used in addition to the dicarboxylic acid component and the glycol component include aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 4-carboxy-4'-hydroxybiphenyl; aliphatic hydroxycarboxylic acids such as glycolic acid and hydroxycaproic acid; C hydroxycarboxylic acids such as propiolactone, butyrolactone, valerolactone, and caprolactone (ε-caprolactone, etc.); ３－１２ lactones; ester-forming derivatives of these comonomer components (C １－６ alkyl ester derivatives, acid halides, acetylated derivatives, etc.

[0045] The melt viscosity of the resin composition constituting resin 31 is preferably 50 Pa·s or more and 350 Pa·s or less. If the melt viscosity of the resin composition is 50 Pa·s or more, when the elastomer enters the recessed portion interfacial region R described below, the elastomer is easily stretched. On the other hand, if the melt viscosity is 350 Pa·s or less, resin 31 easily enters recessed portion 21A, allowing stretched elastomer 32 to be present in recessed portion interfacial region R. The lower limit of the melt viscosity of the resin composition is more preferably 60 Pa·s or more, 70 Pa·s or more, or 100 Pa·s or more, and the upper limit is more preferably 320 Pa·s or less, 300 Pa·s or less, or 280 Pa·s or less. For example, the melt viscosity of the resin composition is more preferably 50 Pa·s or more and 350 Pa·s or less, 70 Pa·s or more and 300 Pa·s or less, or 100 Pa·s or more and 280 Pa·s or less.

[0046] The melt viscosity of the resin composition is measured in accordance with ISO 11433 as follows: A capillary rheometer ("Capillograph (registered trademark)" manufactured by Toyo Seiki Seisaku-sho, Ltd.) is used, a flat die of 1 mmφ×20 mmL is used as a capillary, a barrel temperature is 310° C., and a shear rate is 1000 sec －１ The melt viscosity is measured under the following conditions.

[0047] When the resin 31 is composed of a polyester resin composition, the temperature is 310°C and the shear rate is 1000 sec －１ The melt viscosity of the polyester resin composition measured under the above conditions is preferably 100 Pa·s or more and 300 Pa·s or less, and more preferably 150 Pa·s or more and 280 Pa·s or less, for the same reasons as those for the melt viscosity of the resin composition described above.

[0048] When the resin 31 is composed of a polyarylene sulfide-based resin composition, the temperature is 310° C. and the shear rate is 1000 sec －１ The melt viscosity of the polyarylene sulfide resin composition measured under the conditions above is preferably 100 Pa·s or more and 350 Pa·s or less, and more preferably 150 Pa·s or more and 300 Pa·s or less, for the same reasons as those for the melt viscosity of the resin composition.

[0049] In addition to the melt viscosity characteristics, the crystallization temperature characteristics are also thought to be influential in the properties of resin compositions. When a resin composition with a low recrystallization temperature is used, the resin easily penetrates into recesses on the surface of the metal component due to its properties, improving wettability, resulting in a mechanical bond due to the anchoring effect, and further improving the adhesion at the interface between the component (especially the metal component) and the resin composition.

[0050] <Stretched Elastomer> The stretched elastomer 32 is an elastomer having an aspect ratio (major axis / minor axis), which is the ratio of the major axis to the minor axis, of 1.5 or more in a cross section obtained by cutting the composite molded article 10 in the thickness direction of the resin molded article 30. In this specification, the "minor axis" refers to the shortest axis of the elastomer, and the "major axis" refers to the longest axis of the elastomer. The aspect ratio of the elastomer in the cross section of the composite molded article can be determined from an image obtained using a scanning electron microscope (SEM).

[0051] The aspect ratio of the stretched elastomer 32 is 1.5 or greater, but the aspect ratio of the stretched elastomer 32 is preferably 5 to 30. If the aspect ratio is 5 or greater, the stretched elastomer 32 will be layered, ensuring airtightness not only initially but also after a heat shock test. If the aspect ratio is 30 or less, the elastomer will maintain a single shape in its stretched state. The lower limit of the aspect ratio of the stretched elastomer 32 is more preferably 8 to 30, 11 to 21, or 21 or greater, and the upper limit is preferably 28 to 25, or 20 to 20. For example, the aspect ratio of the stretched elastomer 32 is more preferably 8 to 30, 10 to 25, or 11 to 20.

[0052] In the cross section, at least a portion of the stretched elastomer 32 is located within the recess 21A and within a recess interface region R along the interface IF between the resin 31 and the roughened surface portion 21 in the resin 31. In this specification, the term "recess interface region" refers to a region located within the recess in a cross section obtained by cutting the composite molded product in the thickness direction of the composite molded product, 1 μm away from the interface between the resin and the roughened surface portion toward the interior of the resin, and sandwiched between an imaginary line along this interface and the interface. The recess interface region R in FIG. 2 is a region within the recess 21A that is 1 μm away from the interface IF between the resin 31 and the roughened surface portion 21 toward the interior of the resin 31, and sandwiched between an imaginary line (two-dot chain line) along the interface IF and the interface IF. At least a portion of the stretched elastomer 32 is present within the recess interface region R, but as long as a portion of the stretched elastomer 32 is present within the recess interface region R, other portions of the stretched elastomer 32 may be present outside the recess interface region R. FIG. 2 shows not only stretched elastomer 32 that is entirely within recessed interface region R, but also stretched elastomer 32 that is partially within recessed interface region R and partially outside the recessed interface region.

[0053] At least a portion of the stretched elastomer 32 present in the recessed interface region R is present along the interface IF. By having the stretched elastomer 32 present in this manner, even if the composite molded article 10 expands or contracts during a heat shock test, the stretched elastomer 32 relieves the stress and strain generated at the interface IF between the member 20 and the resin molded article 30, preventing cracks, gaps, and the like from occurring, thereby ensuring good airtightness even after the heat shock test. In this specification, "at least a portion of the stretched elastomer is present along the interface" includes not only cases where at least a portion of the stretched elastomer extends parallel to the interface, but also cases where it extends offset from the interface to an extent that it can be recognized as generally along the interface.

[0054] In the cross section, it is sufficient that one stretched elastomer 32 is present in the recessed interface region R, but it is preferable that two or more stretched elastomers 32 are present. When two or more stretched elastomers 32 are present in the recessed interface region R, it is preferable that the average aspect ratio of the stretched elastomers 32 in the recessed interface region R is in the same range as the above aspect ratio of the stretched elastomers 32. For example, when five or more stretched elastomers are identified in the cross section, the average aspect ratio of the stretched elastomers is the average value of the aspect ratios of three randomly selected stretched elastomers.

[0055] The average aspect ratio of the stretched elastomer 32 is preferably at least twice, and more preferably at least five times, the average aspect ratio of the elastomer present outside the recesses 21A.

[0056] It is preferable that the difference in melt viscosity between resin 31 and elastomer is small. If the difference in melt viscosity between resin 31 and elastomer is small, the elastomer is less likely to be rolled up without being stretched, stretched elastomer 32 is more likely to be formed in the recesses, and stretched elastomer 32 is less likely to peel off from resin 31. Furthermore, even if the difference in melt viscosity between resin and elastomer is large, if the elastomer has a low viscosity, it is presumed that the elastomer will be stretched, and stretched elastomer 32 will be formed in the recesses.

[0057] The melt index (MI) of the elastomer measured under conditions of 190°C and a load of 21 N is preferably 1 g / 10 min or more and 10 g / 10 min or less. If the melt index (MI) of the elastomer is 1 g / 10 min or more, the elastomer can be stretched, and if it is 10 g / 10 min or less, stretched elastomer 32 can be easily formed in the recess interface region R.

[0058] The melting point of the elastomer is preferably 80°C or lower, and more preferably 60°C or lower. If the melting point of the elastomer is 80°C or lower, at least a portion of the elastomer 33 will be more likely to enter the recesses 21A during molding of the resin molded product 30, making it easier to form the stretched elastomer 32. The lower limit of the melting point of the elastomer may be 45°C or higher. The melting point of the elastomer can be determined using a differential scanning calorimeter (DSC).

[0059] The stretched elastomer 32 is not particularly limited, but examples thereof include olefin-based elastomers, styrene-based elastomers, silicone-based elastomers, polyester-based elastomers, polyamide-based elastomers, and urethane-based elastomers.

[0060] The olefin elastomer is a copolymer containing ethylene and / or propylene as a component, and specific examples thereof include an ethylene-propylene copolymer, an ethylene-butene copolymer, an ethylene-octene copolymer, an ethylene-propylene-butene copolymer, an ethylene-propylene-diene copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-vinyl acetate copolymer, and an ethylene-glycidyl methacrylate copolymer, although the elastomer is not limited thereto. Most preferred is an epoxy group-containing olefin copolymer, which has a group reactive with an inorganic filler.

[0061] Furthermore, among olefin-based elastomers, graft copolymers in which one or more polymers or copolymers composed of repeating units represented by the following general formula (1) are chemically bonded in a branched or crosslinked structure to an ethylene-unsaturated carboxylic acid alkyl ester copolymer or an olefin-based copolymer composed of an α-olefin and a glycidyl ester of an α,β-unsaturated acid can also be used.

[0062] In the above formula (1), R is hydrogen or a lower alkyl group, and X is —COOCH ３ , -COOC ２ H ５ , -COOC ４ H ９ , -COOCH ２ CH(C２ H ５ ) C ４ H ９ , -C ６ H ５ and —CN.

[0063] The α-olefin may be a C2-4 olefin such as ethylene or propylene, with ethylene or propylene being preferred. The α,β-unsaturated acid glycidyl ester is preferably glycidyl acrylate or glycidyl methacrylate. Alternatively, a third component such as a C1-12 (meth)acrylic acid ester or vinyl acetate may be copolymerized.

[0064] The olefin and glycidyl ester can be adjusted to be in the range of 30 mol% or more and 90 mol% or less and 70 mol% or more and 10 mol% or less, respectively, in the copolymer, and the third component can be contained in the range of 0 mol% or more and 30 mol% or less.

[0065] The olefin-based elastomer is preferably an ethylene-glycidyl methacrylate copolymer (hereinafter also referred to as EGMA). The ratio of glycidyl methacrylate to ethylene is not particularly limited, but is preferably 1 part by mass to 30 parts by mass, more preferably 3 parts by mass to 20 parts by mass, and even more preferably 8 parts by mass to 15 parts by mass, based on 100 parts by mass of the copolymer, when the modified sites of the copolymer are converted into the mass of each monomer.

[0066] The styrene-based elastomers are composed of a hard segment made of a homopolymer or copolymer of an aromatic vinyl monomer such as styrene, α-methylstyrene, or vinyltoluene, and an α-C copolymer made of an α-olefin (ethylene, propylene, 1-butene, 1-hexene, 1-octene, etc.). ２－１２ Examples include block or graft copolymers (or hydrogenated products thereof) with a soft segment composed of a homopolymer or copolymer of at least one monomer selected from the group consisting of olefins, diene monomers (butadiene, isoprene, etc.), and the like.

[0067] The styrene-based elastomer may also be an elastomer having a reactive functional group, such as an acid-modified elastomer modified with an acid or acid anhydride, such as (meth)acrylic acid or maleic anhydride, or an epoxy-modified elastomer obtained by using a copolymerizable monomer having a glycidyl group or an epoxy group (such as glycidyl (meth)acrylate) or by epoxidizing the unsaturated bond of an elastomer.

[0068] Representative styrene-based elastomers include styrene-diene-styrene block copolymers [styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), etc.], hydrogenated block copolymers [styrene-ethylene-butylene-styrene block copolymer (or hydrogenated (styrene-butadiene-styrene block copolymer)) (SEBS), styrene-ethylene-propylene-styrene block copolymer (or hydrogenated (styrene-isoprene-styrene block copolymer)) (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), hydrogenated polymers of random styrene-butadiene copolymers, etc.], and modified copolymers in which functional groups (epoxy groups, carboxyl groups, acid anhydride groups, etc.) have been introduced into these copolymers [epoxidized styrene-diene copolymers in which the unsaturated bonds of the diene have been epoxidized (epoxidized styrene-diene-styrene block copolymers or hydrogenated polymers thereof, etc.)].

[0069] Silicone elastomers are elastomers containing organopolysiloxane as a main component, and are divided into polydimethylsiloxane-based, polymethylphenylsiloxane-based, and polydiphenylsiloxane-based elastomers. A portion of the organopolysiloxane may be modified with a vinyl group, an alkoxy group, or the like. Specific examples of silicone elastomers include silicone rubber (poly(dimethylsiloxane) and poly(dimethylsiloxane-co-methylvinylsiloxane)).

[0070] Commercially available silicone elastomers include the KE series (manufactured by Shin-Etsu Chemical Co., Ltd.), SE series, CY series, and SH series (all manufactured by Toray Dow Corning Silicone Co., Ltd.).

[0071] Examples of polyester-based elastomers include, but are not limited to, block copolymers having an aromatic polyester such as polyethylene terephthalate or polybutylene terephthalate as a hard segment and a polyether such as polyethylene glycol or polytetramethylene glycol, or an aliphatic polyester such as polyethylene adipate, polybutylene adipate, or polycaprolactone as a soft segment.

[0072] Examples of polyamide elastomers include, but are not limited to, block copolymers having nylon 6, nylon 66, nylon 11, nylon 12, or the like as hard segments and polyether or aliphatic polyester as soft segments.

[0073] Examples of urethane-based elastomers include, but are not limited to, block copolymers having a polyurethane as a hard segment obtained by reacting a diisocyanate such as 4,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tolylene diisocyanate, or hexamethylene diisocyanate with a glycol such as ethylene glycol or tetramethylene glycol, and a polyether such as polyethylene glycol, polypropylene glycol, or polytetramethylene glycol, or an aliphatic polyester such as polyethylene adipate, polybutylene adipate, or polycaprolactone as a soft segment.

[0074] The stretched elastomer 32 is a reactive elastomer, and the reactive elastomer preferably has a glycidyl group. When the member 20 is a metal member, the reactive elastomer having a glycidyl group can enhance the adhesion between the metal member and the resin composition through physical interaction with the surface of the metal member due to van der Waals forces and through the formation of chemical bonds due to intermolecular forces between the elastomer and the functional groups formed on the surface of the metal member. Furthermore, when the member 20 is a metal member, the adhesion between the elastomer and the member 20 can be improved during molding of the resin molded product 30. Therefore, when the resin composition fills the recess 21A, the elastomer is stretched, making it easier to form the stretched elastomer 32.

[0075] <Elastomer with aspect ratio of 1 or more and less than 1.5> The elastomer 33 with aspect ratio of 1 or more and less than 1.5 is an elastomer with an aspect ratio (major axis / minor axis) of 1 or more and less than 1.5 in a cross section when the composite molded article 10 is cut in the thickness direction of the resin molded article 30.

[0076] The elastomer 33 may be present not only inside the recess 21 A but also outside the recess 21 A. The elastomer 33 may be present inside the recess interface region R or outside the recess interface region R.

[0077] Except for the aspect ratio, the elastomer 33 is similar to the stretched elastomer 32. Therefore, the elastomer 33 has the same melting point and melt viscosity as those described in the stretched elastomer 32 section.

[0078] <Inorganic Filler> Inorganic fillers are contained for the purpose of improving performance such as mechanical strength, heat resistance, dimensional stability (resistance to deformation and warpage), and electrical properties. As inorganic fillers, fibrous, powdery, or plate-like fillers are used depending on the purpose. Examples of fibrous fillers include inorganic fibrous materials such as glass fiber, asbestos fiber, carbon fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, boron fiber, potassium titanate fiber, and fibrous metals such as stainless steel, aluminum, titanium, copper, and brass. Particularly representative fibrous fillers are glass fiber and carbon fiber. On the other hand, examples of powdery fillers include carbon black, silica, quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, silicates such as wollastonite, metal oxides such as iron oxide, titanium oxide, zinc oxide, and alumina, metal carbonates such as calcium carbonate and magnesium carbonate, metal sulfates such as calcium sulfate and barium sulfate, silicon carbide, silicon nitride, boron nitride, and various metal powders. Examples of plate-like fillers include mica, glass flakes, and various metal foils. Among these, glass fiber, calcium carbonate, and glass beads are preferably used, or a combination of these is preferred. These inorganic fillers can be used alone or in combination of two or more.

[0079] <Additives> Examples of additives include nucleating agents, pigments such as carbon black and inorganic calcined pigments, antioxidants, stabilizers, plasticizers, lubricants, mold release agents, and flame retardants.

[0080] The inventors conducted extensive research into the airtightness of composite molded articles both initially and after heat shock testing and found that by including an expanded elastomer along the interface within the recessed interfacial region, sufficient airtightness can be ensured not only initially but also after the heat shock test. The heat shock test, also known as a thermal shock test, involves repeatedly subjecting a material to rapid temperature changes, causing it to expand and contract, thereby generating thermal stress and strain within the material, and observing whether defects such as cracks occur in the material. The interface between a component and a resin molded article is particularly prone to defects such as cracks and is a potential starting point for a decrease in airtightness, making gas and liquid leakage likely to occur through this interface. However, by including at least a portion of the expanded elastomer along the interface within the recessed interfacial region, even when the composite molded article expands or contracts during the heat shock test, the expanded elastomer relieves the stress and strain generated at the interface between the component and the resin molded article, preventing cracks and gaps from forming. This is believed to ensure good airtightness even after the heat shock test. According to this embodiment, at least a portion of the stretched elastomer 32 is present along the interface IF within the recessed interface region R, so that sufficient airtightness can be ensured not only initially but also after the heat shock test.

[0081] <<<<Method for Manufacturing a Composite Molded Product>> First, a member 20 having a roughened surface portion 21 is prepared. The roughened surface portion 21 may be formed by forming metal clusters by laser processing as described above, or by etching or blasting. For example, when the member 20 is made of metal and the roughened surface portion 21 is formed by laser processing, the member 20 having the roughened surface portion 21 can be formed as follows. When a laser is irradiated onto the metal member 20, the metal on the surface of the member 20 is melted by the high-energy beam of the laser, pushed out to the outside of the irradiated area, and then solidified into spherical shapes due to surface tension. The surface of the member 20 is scanned with the laser at a fine pitch, generating spherical objects that overlap to form metal clusters. Alternatively, the member 20 sublimes, and the scattered liquid metal particles solidify (re-adhere) and accumulate, forming spherical metal clusters, thereby forming the roughened surface portion 21.

[0082] When forming metal clusters, if the laser output (energy per unit time) is low, the metal on the metal surface may not melt, or sublimation or scattering of liquid metal particles may not occur. Therefore, the laser output for forming spherical metal clusters is determined appropriately depending on the metal material constituting the member 20. Furthermore, in order to make the molten metal extruded outside the laser irradiation area into minute spheres, the laser scanning pitch is preferably 30 μm or less, more preferably 20 μm or less, or even more preferably 10 μm or less.

[0083] The laser output and irradiation speed determine the energy imparted to the metal surface per unit area per unit time. Therefore, in addition to the laser output, the irradiation speed is also a factor in forming spherical metal clusters. The irradiation speed is preferably 600 mm / s or more and 2000 mm / s or less. Appropriate laser output and irradiation speed cause a local temperature rise on the metal surface in an extremely short time, thereby forming spherical metal clusters. The irradiation speed is preferably 800 mm / s or more and 2000 mm / s or less, more preferably 900 mm / s or more and 1800 mm / s or less, and even more preferably 1000 mm / s or more and 1500 mm / s or less.

[0084] A resin composition containing an elastomer is also prepared. When the resin composition is molded at a molding temperature equal to or higher than the melting point of the elastomer so as to fill the recesses 21A of a member 20 having a roughened surface 21 with recesses 21A on at least a portion of its surface 20A, the elastomer stretches within the recesses 21A and in the recess interface region R along the interface IF, forming a stretched elastomer 32 having an aspect ratio of 1.5 or greater along the interface IF. The elastomer that is not stretched or stretched to a small degree is designated as elastomer 33. The reason for molding at a temperature equal to or higher than the melting point of the elastomer is that the elastomer softens and becomes more easily stretched when molded at a molding temperature equal to or higher than the melting point of the elastomer.

[0085] The content of the elastomer in the resin composition is preferably 3% by mass or more and 30% by mass or less. If the content of the elastomer is 3% by mass or more, the stretched elastomer 32 can be effectively present in the recessed portion interfacial region R when the resin molded product 30 is formed. If the content of the elastomer is 30% by mass or less, the elastomer content is not too high, so that the viscosity (fluidity) is suitable for injection molding, the resin composition can enter the recessed portion 21A, and at least a portion of the stretched elastomer 32 can be present in the recessed portion interfacial region R.

[0086] Next, insert molding is performed using a resin composition and the member 20 having the roughened surface portion 21 as an insert member. As a result, the resin and elastomer fill the recesses 21A of the roughened surface portion 21. When the elastomer fills the recesses 21A, it stretches to form stretched elastomer 32. In this way, a composite molded product 10 can be obtained.

[0087] In the insert molding, the injection speed is preferably in the range of 15 mm / sec to 100 mm / sec. In insert molding, when molten resin is injected into a mold, it cools upon contact with the mold wall and forms a solidified layer (skin layer). However, the molten resin flows between the two solidified layers (skin layers), generating shear forces between the solidified layer (skin layer) and the flowing layer. Thus, the shear forces generated between the solidified layer (skin layer) and the flowing layer cause the molecular chains to flow while being stretched in the flow direction. Therefore, when the resin composition enters the recess 21A, the molecular chains are oriented by the shear forces, which presumably makes it easier for the elastomer to form a stretched state. The shear rate can be calculated from the shape and thickness of the molded product, the cross-sectional area and volumetric flow rate of the injection molding machine, etc., and when the injection rate is 15 mm / sec or more and 100 mm / sec or less, the shear rate is estimated to be in the range of 100 (1 / sec) or more and 10,000 (1 / sec) or less. By performing insert molding under the above conditions, the stretched elastomer 32 can be formed in a state where at least a portion of the stretched elastomer 32 is in the recessed interface region R along the interface IF.

[0088] To explain the present invention in detail, the following examples are provided, but the present invention is not limited to these. Fig. 5A is a plan view of a composite molded product according to Example 4, Fig. 5B is a cross-sectional view taken along the X-X line in Fig. 5A, and Fig. 6 is a schematic diagram of a test apparatus used in an airtightness test. Fig. 7 is a scanning electron microscope photograph of a cross section of the composite molded product according to Example 4 when cut in the thickness direction of the composite molded product. Fig. 8 is a scanning electron microscope photograph of a cross section of the composite molded product according to Comparative Example 2 when cut in the thickness direction of the composite molded product. Figs. 9A to 9E are schematic diagrams illustrating the steps for producing test pieces according to Reference Examples 1 to 5.

[0089] <Preparation of Resin Composition> First, the components were blended to obtain the following resin composition. (Resin Composition 1) Polyarylene sulfide resin 1 (manufactured by Polyplastics Co., Ltd., melt viscosity: 20 Pa·s (shear rate: 1000 sec) －１ , temperature 310°C): 100 parts by mass Reactive elastomer 1 (ethylene (E) group: 67% by weight, glycidyl methacrylate (GMA) group: 6% by weight, methyl acrylate (MA) group: 27% by weight, melting point: 52°C): 14.2 parts by mass Glass fiber 1 (Nippon Electric Glass Co., Ltd., "ECS03T747H"): 70.8 parts by mass Calcium carbonate 1 (Asahi Komatsu Co., Ltd., "MC-35W"): 47.2 parts by mass Pentaerythritol stearate ester (Emery Oleochemicals Japan, "LOXYOL VPG861"): 0.7 parts by mass Carbon black (Mitsubishi Chemical Corporation, "MA600B"): 0.5 parts by mass Antioxidant 1 (BASF Japan Ltd., "Irganox 1010"): 0.7 parts by mass

[0090] (Resin Composition 2) Polyarylene sulfide resin 2 (manufactured by Polyplastics Co., Ltd., melt viscosity: 100 Pa·s (shear rate: 1000 sec) －１, temperature: 310°C): 100 parts by mass Reactive elastomer 1 (ethylene (E) group: 67% by weight, glycidyl methacrylate (GMA) group: 6% by weight, methyl acrylate (MA) group: 27% by weight, melting point: 52°C): 14.2 parts by mass Glass fiber 1 (Nippon Electric Glass Co., Ltd., "ECS03T747H"): 70.8 parts by mass Calcium carbonate 1 (Asahi Komatsu Co., Ltd., "MC-35W"): 47.2 parts by mass Pentaerythritol stearate ester (Emery Oleochemicals Japan, "LOXYOL VPG861"): 0.7 parts by mass Carbon black (Mitsubishi Chemical Corporation, "MA600B"): 0.5 parts by mass Antioxidant 1 (BASF Japan Ltd., "Irganox 1010"): 0.7 parts by mass

[0091] (Resin Composition 3) Polyarylene sulfide resin 3 (manufactured by Polyplastics Co., Ltd., melt viscosity: 28 Pa·s (shear rate 1000 sec －１ , temperature 310°C): 100 parts by mass; Reactive elastomer 2 (ethylene (E) group: 70% by weight, glycidyl methacrylate (GMA) group: 3% by weight, methyl acrylate (MA) group: 27% by weight, melting point: 52°C): 10.5 parts by mass; Glass fiber 2 ("ECS03T747H" manufactured by Nippon Electric Glass Co., Ltd.): 61.2 parts by mass; Pentaerythritol stearate ester ("LOXYOL VPG861" manufactured by Emery Oleochemicals Japan): 0.9 parts by mass; Carbon black ("MA600B" manufactured by Mitsubishi Chemical Corporation): 0.3 parts by mass; Antioxidant 1 ("Irganox 1010" manufactured by BASF Japan Ltd.): 0.5 parts by mass.

[0092] (Resin Composition 4) Polyarylene sulfide resin 1 (manufactured by Polyplastics Co., Ltd., melt viscosity: 20 Pa·s (shear rate: 1000 sec) －１ , temperature: 310°C): 43 parts by mass Polyarylene sulfide resin 3 (manufactured by Polyplastics Co., Ltd., melt viscosity: 28 Pa s (shear rate: 1200 sec －１, temperature: 310°C): 57 parts by mass; Reactive elastomer 3 (E group: 59.5 wt%, GMA group: 10.5 wt%, MA group: 0 wt%, melting point: 96.7°C): 14.2 parts by mass; Glass fiber 2 (Nippon Electric Glass Co., Ltd., "ECS03T747"): 85.6 parts by mass; Calcium carbonate 2 (Toyo Fine Chemical Co., Ltd., Whiten P-30): 36.7 parts by mass; Pentaerythritol stearate ester (Emery Oleochemicals Japan, LOXYOL VPG861): 1.0 part by mass; Carbon black (Mitsubishi Chemical Corporation, "MA600B"): 1.0 part by mass; Antioxidant 2: 0.5 parts by mass (BASF Japan Ltd., "Irganox 245")

[0093] (Resin Composition 5) Polyarylene sulfide resin 3 (manufactured by Polyplastics Co., Ltd., melt viscosity: 28 Pa·s (shear rate 1000 sec) －１ , temperature 310°C): 100 parts by mass Glass fiber 3 ("CS GL-HF" manufactured by Owens Corning Manufacturing Co., Ltd.): 70.5 parts by mass Pentaerythritol stearate ester ("LOXYOL VPG861" manufactured by Emery Oleochemicals Japan): 0.4 parts by mass Carbon black ("MA600B" manufactured by Mitsubishi Chemical Corporation): 0.9 parts by mass Alkoxysilane compound ("KBE-903P" manufactured by Shin-Etsu Chemical Co., Ltd.): 1.1 parts by mass

[0094] Example 1 First, a copper member made of C1100 and having a busbar shape as shown in Figures 1A and 1B, with a length of 88.0 mm, a width of 20.1 mm, and a thickness of 1.6 mm, was prepared. Then, using a fiber laser processing machine ("ML-7350DL" manufactured by Amada Weld Tech Co., Ltd.), a laser was irradiated onto the front, back, and both side surfaces of the copper member under the conditions shown in Table 1, forming copper clusters in the center of each surface and forming a roughened surface portion with a width of 5 mm. This resulted in the formation of a copper member having a roughened surface portion on each surface.

[0095] Then, a copper member having a roughened surface was used as an insert member and insert molding was performed using resin composition 1 under the following conditions. A resin molded product was formed on the surface of the copper member to have the shape shown in FIGS. 1A and 1B, thereby forming a composite molded product consisting of the copper member and resin molded product according to Example 1. The resin molded product was insert molded to cover the roughened surface. The insert molding conditions were as follows. The diameter of the disc portion of the resin molded product was 42 mm, the thickness T1 (see FIG. 1A) was 5.0 mm, the outer diameter of the annular portion was 33 mm, the inner diameter was 31 mm, the thickness T2 (see FIG. 1A) was 4.6 mm, the length of the flat portion was 15.5 mm, the width was 24.3 mm, and the thickness T3 (see FIG. 1B) was 5.8 mm. Injection molding machine: Sodick TR100EH Cylinder temperature: 330°C Mold temperature: 150°C Injection speed: 70 mm / s Holding pressure: 50 MPa Cooling time: 20 seconds

[0096] Example 2 In Example 2, a composite molded article according to Example 2 was obtained in the same manner as in Example 1, except that Resin Composition 2 was used instead of Resin Composition 1.

[0097] Example 3 In Example 3, a composite molded article was obtained in the same manner as in Example 1, except that the laser output was changed to 19.5 W and resin composition 2 was used instead of resin composition 1.

[0098] Example 4 First, an annular aluminum member 61 made of A5052 and having an outer diameter of φ50 mm, an inner hole diameter of φ20 mm, and a thickness of 1 mm, as shown in Figures 5A and 5B, was prepared. Then, using a fiber laser processing machine (ML-7350DL manufactured by Amada Weld Tech), a laser was irradiated concentrically over a range of φ20 mm to φ26 mm on the surface of the aluminum member 61 (the bonding surface with the resin molded product 62, described below) under the conditions shown in Table 1, forming aluminum clusters and forming a roughened surface portion. This resulted in the formation of an aluminum member 61 having a roughened surface portion on its surface.

[0099] Then, insert molding was performed using resin composition 3 on an aluminum member 61 having a roughened surface, with the aluminum member 61 as an insert member under the following conditions, and a resin molded product was formed on the surface of the aluminum member 61 so as to have the shape shown in Figures 5A and 5B, thereby forming a composite molded product 60 consisting of the aluminum member 61 and resin molded product 62 according to Example 4. The insert molding conditions were as follows. The resin molded product had an outer diameter of φ30 mm and a thickness of 3 mm. Injection molding machine: Sodick TR100EH; Cylinder temperature: 320°C; Mold temperature: 150°C; Injection speed: 15 mm / s; Holding pressure: 50 MPa; Cooling time: 20 sec

[0100] Example 5 In Example 5, a composite molded product was obtained in the same manner as in Example 4, except that a copper member made of C1100 having the same shape and dimensions as the aluminum member was used instead of the aluminum member.

[0101] Comparative Example 1 In Comparative Example 1, a composite molded article was obtained in the same manner as in Example 1, except that Resin Composition 4 was used instead of Resin Composition 1.

[0102] <Comparative Example 2> In Comparative Example 2, a composite molded product was obtained in the same manner as in Example 1, except that Resin Composition 5 was used instead of Resin Composition 1 and no elastomer was added.

[0103] <Confirmation of Presence of Stretched Elastomer, etc., and Calculation of Average Aspect Ratio> For the composite molded products of Examples 1 to 5 and Comparative Examples 1 and 2, the cross sections of the composite molded products were observed using a scanning electron microscope ("SU5000" manufactured by Hitachi High-Technologies Corporation) to confirm whether or not at least a portion of the stretched elastomer was present along the copper member-resin molded product interface or the aluminum member-resin molded product interface within the recessed interfacial region of the copper clusters present in the roughened surface portion of the copper member or the aluminum clusters present in the roughened surface portion of the aluminum member, and whether or not an elastomer having an aspect ratio of 1 or more and less than 1.5 was present outside the recessed interfacial region within the recessed portion. Specifically, the composite molded product was cut in the thickness direction of the composite molded product, and the cross section was observed at a magnification of 10,000 times to confirm the presence of the stretched elastomer and the elastomer having an aspect ratio of 1 or more and less than 1.5. Furthermore, when at least a portion of the stretched elastomer was confirmed along the interface within the recessed interface region, the minor axis and major axis of the stretched elastomer were measured to determine the aspect ratio of the stretched elastomer, and the average aspect ratio, which is the arithmetic mean value, was calculated.

[0104] <Airtightness Test> An airtightness test was conducted on the joint surface between the copper member or aluminum member and the resin molded product in the composite molded products according to Examples 1 to 5 and Comparative Examples 1 and 2. The configuration of the test equipment for the airtightness test (helium leak test, vacuum method) is shown in Figure 6.

[0105] As shown in FIG. 6 , the testing device 70 included a chamber 71 sealed from the outside. A jig 72 and a composite molded article 80 were placed inside the chamber 71. The jig 72 had a rectangular parallelepiped shape with a bottom, and the composite molded articles 80 according to Examples 1 to 5 and Comparative Examples 1 and 2 were placed on top of the jig 72, sealing the interior of the jig 72 from the rest of the chamber 71. With a valve 73 open, the interior of the jig 72 was evacuated by a vacuum pump 74. Then, with the valve 73 closed, the chamber 71 was filled with helium gas from a helium cylinder 75. Helium gas leaking from the joints of the composite molded article 80 inside the chamber 71 was detected by a helium detector 76. A control device 77 displayed the helium gas detection results. A G-FINE helium leak tester manufactured by Cosmo Instruments Co., Ltd. and an L300i helium leak tester manufactured by Inficon Co., Ltd. were used as the helium detector 76.

[0106] The helium pressure in the chamber 71 was set to 400 kPa, and the vacuum pressure in the jig 72 was set to 100 kPa. If the airtightness of the joint between the copper or aluminum member and the resin molded product of the composite molded product 80 is low, the helium gas in the chamber 71 will flow into the jig 72 and be detected by the helium detector 76. In this test, the helium pressure (detected pressure) detected by the helium detector 76 was 1.0 × 10 －７ P.A.M. ３ / s or more is judged to be poor airtightness, and 1.0 x 10 －７ P.A.M. ３ When the value was less than 1 / s, the airtightness was judged to be good.

[0107] <Heat Shock Test> A heat shock test was performed on the composite molded articles of Examples 1 to 5 and Comparative Examples 1 and 2 using thermal shock testers ES-106LH and ES-77LHS manufactured by Hitachi Appliances, Inc. The heat shock test was performed for 250 cycles, with one cycle consisting of leaving the resin molded article at -40°C for 30 minutes and leaving it at 150°C for 30 minutes. After 250 cycles, the resin molded article was removed from the tank and subjected to the above-mentioned airtightness test to evaluate its cold and thermal shock resistance (heat shock resistance).

[0108] The results are shown in Table 1 below.

[0109] As shown in Table 1 and FIG. 8 , the composite molded articles of Comparative Examples 1 and 2 were unable to achieve airtightness initially or after the heat shock test because at least a portion of the stretched elastomer was not present in the recessed interfacial region. Since the presence of the stretched elastomer was not confirmed in Comparative Example 1, the average aspect ratio of the stretched elastomer in Comparative Example 1 was not measured. In contrast, as shown in Table 1 and FIG. 7 , the composite molded articles of Examples 1 to 5 had at least a portion of the stretched elastomer present in the recessed interfacial region along the copper member-resin molded article interface or the aluminum member-resin molded article interface. Therefore, it was confirmed that the bonded portions between the copper member and the polyarylene sulfide-based resin and the bonded portions between the aluminum member and the polyarylene sulfide-based resin were highly airtight at the initial stage and after the heat shock test. This confirmed that sufficient airtightness was achieved initially and after the heat shock test by having the stretched elastomer present in the recessed interfacial region along the copper member-resin molded article interface or the aluminum member-resin molded article interface.

[0110] Reference Examples 1 to 5: Sample pieces for Reference Examples 1 to 5 were prepared to examine the relationship between the melting point of the reactive elastomer and the average aspect ratio of the reactive elastomer after molding. First, the resin compositions 1 to 4 were molded under the following conditions to obtain disk-shaped molded articles with a diameter of 70 mm and a thickness of 3 mm and a 30 μm-thick flash (see FIG. 9A). Flash was formed on the molded articles to simply replicate the state in which the resin compositions 1 to 4 had entered the roughened surface portion with a recess. (Molding Conditions) Molding machine: Toshiba Corporation EC60N i1.5A; Cylinder temperature: 320°C; Mold temperature: 150°C; Injection speed: 30 mm / s; Holding pressure: Minimum filling pressure (minimum pressure required to completely fill the cavity) + 5 MPa; Cooling time: 10 seconds.

[0111] A burr-containing section measuring 0.2-0.4 mm in length and 6 mm in base width was cut out of the resulting molded product with burrs using a band saw (manufactured by YS Koki Co., Ltd.) (see Figure 9B). The cut-out burr-containing section was then embedded in epoxy resin to protect it (see Figure 9C). The burr-containing section embedded in the epoxy resin was then cut out using a polishing machine (manufactured by Buhler Co., Ltd.) until the thickness of the burr-containing section was reduced to approximately half, exposing the cross-section (see Figure 9D). The exposed burr-containing section was then cut out using a diamond cutter (manufactured by Buhler Co., Ltd.) and fixed to a sample stage with hot wax (manufactured by Maruto Co., Ltd.). The cross-section of the burr-containing section was milled under the following conditions: (Cutting Conditions) Cutting Machine: ArBrade 5000 (manufactured by Hitachi High-Tech Corporation); Applied Voltage: 3.4 kV; Discharge Voltage: 1.2 kV; Cooling: None; Machining Time: 4.0 h; Intermittent Time: None.

[0112] The cut cross section of the burr-containing portion was then polished with grit sizes #400, #1000, and #2000 in this order to obtain test pieces according to Reference Examples 1 to 5 (see FIG. 9E).

[0113] The burr-containing portions of the obtained test pieces according to Reference Examples 1 to 5 were observed with an SEM under the following conditions to obtain SEM observation images: (SEM observation conditions) Apparatus: Phenom-World tabletop SEM-EDX Phenom Pro X Conditions: backscattered electron image, 10 kV Observation magnification: 10,000 times

[0114] Then, from the SEM observation images, five elastomers near the surface layer of the burrs were randomly selected for each sample piece, and the aspect ratio was calculated from the ratio of the major axis to the minor axis of each elastomer, and the calculated aspect ratios were arithmetically averaged to obtain the average aspect ratio.

[0115] The results are shown in Table 2. The "ratio" in Table 2 refers to the ratio of the aspect ratio of the elastomer in the burr in the test piece of Reference Examples 1 to 4 when the aspect ratio of the elastomer in the burr in the test piece of Reference Example 5 is taken as 1.

[0116] As shown in Table 2, the elastomer in the burrs of the test pieces of Reference Examples 1 to 4 was more stretched than the elastomer in the burr of the test piece of Reference Example 5. This is thought to be because the elastomer in the burr of the test piece of Reference Example 5 had a melting point above 80°C, whereas the elastomer in the burrs of the test pieces of Reference Examples 1 to 4 had a melting point of 80°C or less. From the results of Reference Examples 1 to 5, it is thought that when the melting point of the elastomer is low, at least a portion of the elastomer tends to enter the recesses during molding of the resin molded product, making it easier to form a stretched elastomer.

[0117] Reference Signs List 10 Composite molded product 20 Member 20A Surface 21 Roughened surface portion 21A Concave portion 21B Convex portion 30 Resin molded product 31 Resin 32 Stretched elastomer 33 Elastomer IF Interface

Claims

1. A composite molded article comprising a member and a resin molded article joined to the member, wherein the member has a surface roughened portion having recesses on at least a part of the surface of the member, the resin molded article includes at least resin that has entered the recesses and a stretched elastomer that is present in the resin and has an aspect ratio, which is the ratio of the major axis to the minor axis in a cross section obtained by cutting the composite molded article in the thickness direction thereof, of 1.5 or more, and at least a part of the stretched elastomer is present along the interface between the member and the resin molded article within a recess interface region that is located within the recesses and along the interface in the cross section.

2. The composite molded article according to claim 1, wherein the stretched elastomer is a reactive elastomer and the reactive elastomer has a glycidyl group.

3. The composite molded article according to claim 1, wherein the resin is composed of a polyarylene sulfide - based resin composition and the melt viscosity of the polyarylene sulfide - based resin composition is 10 Pa·s or more and 350 Pa·s or less.

4. The composite molded article according to claim 1, wherein the resin is composed of a polybutylene terephthalate - based resin composition and the melt viscosity of the polybutylene terephthalate - based resin composition is 50 Pa·s or more and 300 Pa·s or less.

5. The composite molded article according to claim 1, wherein the member is a metal member and the surface roughened portion is a metal cluster.

6. A resin composition used for manufacturing the composite molded article according to claim 1, the resin composition including a resin and an elastomer having an aspect ratio, which is the ratio of the major axis to the minor axis, of 1 or more and less than 1.5, wherein when the resin composition is molded so as to enter the recesses of a member having a surface roughened portion having recesses on at least a part of the surface thereof at a molding temperature equal to or higher than the melting point of the elastomer, the elastomer is stretched within the recesses and within a recess interface region that is located along the interface between the member and the resin composition and along the interface, and a stretched elastomer having an aspect ratio of 1.5 or more along the interface is formed.

Images