Composite molded articles and resin compositions

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

Reference to related applications

[0001] This application enjoys priority from the preceding Japanese application, Japanese Patent Application No. 2024-4923 (filing date: January 16, 2024), the entirety of which disclosure is incorporated herein by reference. [Technical Field]

[0002] This invention relates to composite molded articles and resin compositions. [Background technology]

[0003] By combining materials with different properties, such as electrically conductive materials like metals and electrically insulating materials like resins, lightweight, high-strength, or high-performance parts are used in a variety of fields. For example, metal-resin composite molded products, which are made by joining metal components and thermoplastic resins, are used in automotive interior components such as console boxes around the instrument panel, engine components, interior parts, housings for electronic devices such as digital cameras and mobile phones, interface connection parts, and power terminal parts.

[0004] While methods such as adhesive bonding and screw fastening are commonly known for joining different materials like metals and resins, they are undesirable due to the increased number of steps and parts involved. Therefore, various methods have been proposed for joining components made of metal or other materials with resin materials.

[0005] For example, Patent Document 1 describes a method of laser processing the surface of a metal material in one scanning direction and then laser processing it in another scanning direction intersecting that scanning direction, and then joining a different material to this surface. Patent Document 2 describes a method of improving the bonding strength when joining a resin molded product to a metal plate by keeping the undercut rate of the irregularities within a predetermined range when forming irregularities on the surface of the metal plate. Patent Document 3 describes a composite molded product of metal and resin in which crater-like depressions are formed in the metal using laser light or the like, and granular sputter is formed on the flank-like raised areas where the metal surface has melted and scattered. Patent Document 4 describes a composite structure in which a surface-roughened metal member and a polyarylene sulfide resin composition member are joined, wherein 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, the number average value of the interface development area ratio (Sdr) is in the range of 5 or more, 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 creating an insert mold made of a resin material and a metal material that ensures airtightness and has excellent durability. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 4020957 [Patent Document 2] Japanese Patent Publication No. 2020-116806 [Patent Document 3] Japanese Patent Publication No. 2013-71312 [Patent Document 4] Patent No. 6819798 [Patent Document 5] Patent No. 6615478 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, conventional methods for joining metal components to resin materials cannot adequately ensure airtightness at the joint between the component and the resin material (i.e., problems such as gaps forming at the joint between the component and the resin material may occur), and there is a need to improve this aspect. Furthermore, when composite molded products are used in environments with large temperature fluctuations, such as around automobile engines, the expansion and contraction rates (so-called linear expansion coefficients) due to temperature changes are extremely different between resin and metal, which can lead to the following problems. For example, if the resin component of a metal-resin composite molded product is thin-walled or has areas with large changes in wall thickness, or if the metal component has sharp corners, there have been problems such as the metal-resin composite molded product breaking 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 long-term temperature changes.

[0008] This invention was made to solve the above problems. Specifically, it aims 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 produce such a composite molded article. [Means for solving the problem]

[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 a recess on at least a part of the surface of the member, and the resin molded product comprises at least a resin that has entered into the recess and a stretched elastomer present in the resin, wherein in a cross-section when the composite molded product is cut in the thickness direction of the resin molded product, the aspect ratio, which is the ratio of the major axis to the minor axis, is 1.5 or more, and at least a part of the stretched elastomer is located in the recess in the cross-section and is present along the interface in a recess interface region along the interface between the member and the resin molded product.

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

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

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

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

[0014] [6] A resin composition used for producing the composite molded article 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. When the resin composition is molded so as to enter into the concave portions of a member having surface roughened portions having concave portions on at least a part of the surface at a molding temperature not lower than the melting point of the elastomer, the elastomer extends within the concave portions and in a concave interface region along the interface between the member and the resin composition, and an extended elastomer having an aspect ratio of 1.5 or more along the interface is formed. ]

[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 capable of obtaining such a composite molded article.

Brief Description of the Drawings

[0016] [Figure 1]Figure 1A is a plan view of the composite molded product according to the embodiment, and Figure 1B is a side view of the composite molded product according to the embodiment. [Figure 2] Figure 2 is an enlarged cross-sectional view of a portion of the composite molded product shown in Figure 1, when it is cut in the thickness direction of the composite molded product. [Figure 3] Figure 3A is a plan view of the component shown in Figure 1, and Figure 3B is a side view of the component shown in Figure 1. [Figure 4] Figure 4 schematically illustrates the state of the interface between a component and a resin molded product, depending on the size of the Spc on the surface of the component in a composite molded product. [Figure 5] Figure 5A is a plan view of the composite molded product according to Example 4, and Figure 5B is a cross-sectional view of Figure 5A, XX. [Figure 6] Figure 6 is a schematic diagram of the test apparatus used in airtightness testing. [Figure 7] Figure 7 is a scanning electron microscope image of a cross-section of the composite molded product according to Example 4, when it is cut in the thickness direction of the composite molded product. [Figure 8] Figure 8 is a scanning electron microscope image of a cross-section of the composite molded product according to Comparative Example 2, when it is cut in the thickness direction of the composite molded product. [Figure 9] Figures 9A to 9E schematically show the process for preparing test specimens related to Reference Examples 1 to 5. [Modes for carrying out the invention]

[0017] The following describes composite molded articles and resin compositions according to embodiments of the present invention. Figure 1A is a plan view of a composite molded article according to this embodiment, Figure 1B is a side view of a composite molded article according to this embodiment, and Figure 2 is an enlarged cross-sectional view of a part of the composite molded article shown in Figure 1 when it is cut in the thickness direction of the composite molded article. Figure 3A is a plan view of the member shown in Figure 1, and Figure 3B is a side view of the member shown in Figure 1. Figure 4 is a diagram that schematically illustrates the state of the interface between the member and the resin molded article according to 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 Figure 1 comprises a member 20 and a resin molded product 30 joined to the member 20. The composite molded product 10 shown in Figure 1 is a busbar. However, composite molded products are not limited to busbars and can be used in a variety of applications. For example, composite molded products may be interior components of automobiles such as console boxes around the instrument panel, engine components, interior parts, housings of electronic devices such as digital cameras and mobile phones, interface connection parts, or power terminal parts.

[0019] <<Components>> The member 20 has a surface roughening portion 21 (see Figures 2, 3A, and 3B) having recesses 21A in at least a part of the surface 20A of the member 20, and two through holes 22 (see Figures 1A and 3A) that penetrate in the thickness direction of the member 20. Note that the member 20 does not need to have the through holes 22 as long as it has the surface roughening portion 21. The surface roughening portion 21 is uneven, and the recesses 21A present in the surface roughening portion 21 are filled with resin 31, which will be described later, as shown in Figure 2.

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

[0021] Since the surface roughened portion 21 has an uneven surface, it has not only recesses 21A but also protrusions 21B. The recesses 21A are located between the protrusions 21B. In Figure 2, the recesses 21A refer to the region sandwiched between the imaginary line (dashed line) connecting the tops of the protrusions 21B and the surface of the surface roughened portion 21. The method for forming the surface roughened portion 21 can be any conventionally known method, for example, a method of chemically or mechanically roughening the surface of the member 20. Specifically, this includes methods such as forming metal clusters by laser irradiation, blasting methods such as sandblasting and shot blasting, etching methods, immersion methods with corrosive aqueous solutions or suspensions, and anodic oxidation methods.

[0022] The arithmetic mean curvature (Spc) of the peaks in the surface roughened portion 21 is preferably between 2000 (1 / mm) and 4500 (1 / mm). 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 points (peaks) in contact with the resin molded product are rounded, while a large Spc indicates that the points in contact with the resin molded product are pointed.

[0023] If the Spc of the surface roughened portion 21 is within the above range, the formation of a gap between the member 20 and the resin molded product 30 can be further suppressed, so that airtightness can be more sufficiently ensured not only initially but also after the heat shock test. This can be inferred as follows. Figures 4A to 4C schematically show the joint surface between member 40 and resin molded product 50 in the case of a large value ("large Spc"), a medium value ("medium Spc"), and a small value ("small Spc") for the peak of the surface roughened portion 41 formed on the surface 40A of member 40. When the Spc of the surface roughened portion 41 of member 40 is large (see Figure 4A), the peak of the surface roughened portion 41 has a sharp shape. When the resin composition in contact with the surface roughened portion 41 cools, shrinkage (shrinkage) 51 occurs. However, if the peaks of the surface roughened portion 41 are sharp, gaps are likely to form between the resin composition and the member 40 at the joint surface of these peaks, which is disadvantageous for achieving high airtightness. On the other hand, when the Spc of the surface roughened portion 41 is small (see Figure 4C), the surface roughened portion 41 has a surface texture that changes gradually as a whole. The surface area of ​​the joint between the member 40 and the resin molded product 50 is small, and it is 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 surface roughened portion 41 is moderate (Figure 4B), the molten resin composition penetrates the surface roughened portion 41 sufficiently, and the recesses 41A formed in the surface roughened 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, it is less likely that loosening of the joint (leak path) caused by the expansion and contraction of the resin constituting the resin molded product that occurs during the heat shock test will be formed, and it is presumed that the adhesion between the component 20 of the composite molded product 10 and the resin molded product 30 can be maintained at an extremely high level even after the heat shock test.

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

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

[0026] When member 20 is a metal member and the protrusion 21B is composed of metal clusters, in order to adjust Spc to be within a desired range, the energy applied to the surface that forms the bonding surface between the metal member and the resin molded product by laser irradiation is controlled. When a pulsed laser is used as the laser, if the average output is P and the frequency is f, the energy E per pulse is expressed as P / f. Therefore, by adjusting the average output P (so-called laser output) and / or the frequency f, the energy applied to the surface that forms the bonding 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, so Spc tends to decrease. Conversely, decreasing the frequency of the pulsed laser increases the amount of energy per pulse applied to the surface of the metal member, so Spc tends to increase, but Spc saturates when the amount of energy becomes sufficiently large.

[0027] The particle size of the particles constituting the metal cluster 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 can fill the recesses, which are the gaps between the particles constituting the metal cluster, thereby further improving adhesion. If the particle size is 500 μm or less, gaps with the metal member are less likely to occur due to resin shrinkage after molding, and airtightness can be more sufficiently ensured.

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

[0029] Furthermore, if the constituent material of member 20 is metal, the surface 20A of member 20 may be subjected to surface treatment such as anodizing or painting. From the viewpoint of lightness and strength, it is preferable to use aluminum, magnesium, copper, or titanium as the metal, and in applications where conductivity is required, such as terminals, it is more preferable to use aluminum or copper, with copper being particularly preferred. In addition, in applications where rigidity is required in thin walls, it is particularly preferable to use magnesium, titanium, and especially titanium.

[0030] <<Resin molded products>> The resin molded product 30 includes resin 31 that has entered into recesses 21A present in at least the surface roughened portion 21, and stretched elastomer 32 present in the resin 31, 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 addition to the resin 31 and the stretched elastomer 32, the resin molded product 30 may also include elastomer 33 having an aspect ratio of 1 or more and less than 1.5, inorganic fillers and / or additives.

[0031] The resin molded product 30 shown in Figures 1A and 1B covers a part of the member 20. The resin molded product 30 has a disc portion 30A, an annular portion 30B adjacent to the disc portion 30A and having a smaller outer diameter than the disc portion 30A, and a flat portion 30C located on both outer sides of the disc portion 30A in the longitudinal direction of the member 20 and adjacent to the disc 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 resins such as polypropylene resin, polyethylene resin, poly(1-)butene resin, and polypentene resin; polyester resins such as polybutylene terephthalate resin (PBT), polyethylene terephthalate resin (PET), and polytrimethylene terephthalate resin (PTT); polyacetal resins; polyarylene sulfide resins such as polyphenylene sulfide resin; and polyamide resins. Resin mixtures obtained by blending multiple resins are also included in the above resins. Polyarylene sulfide 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) Polyarylene sulfide resins are polymer compounds mainly composed of repeating units of -(Ar-S)- (where Ar is an arylene group), and in this embodiment, polyarylene sulfide resins with generally known molecular structures can be used.

[0034] Examples of the above-mentioned arylene groups include p-phenylene groups, m-phenylene groups, o-phenylene groups, substituted phenylene groups, p,p'-diphenylene sulfone groups, p,p'-biphenylene groups, p,p'-diphenylene ether groups, p,p'-diphenylene carbonyl groups, and naphthalene groups. The PAS resin may be a homopolymer consisting only of the above-mentioned repeating units, or a copolymer containing the following different repeating units may be preferred from the viewpoint of processability, etc.

[0035] As the homopolymer, a polyphenylene sulfide resin (also called PAS resin) is preferably used, in which p-phenylene groups are used as the arylene groups and p-phenylene sulfide groups are used as repeating units. Furthermore, as the copolymer, two or more different combinations of arylene sulfide groups consisting of the aforementioned arylene groups can be used, but a combination containing p-phenylene sulfide groups and m-phenylene sulfide groups is particularly preferred. Among these, a combination containing 70 mol% or more, preferably 80 mol% or more, of p-phenylene sulfide groups is suitable in terms of physical properties such as heat resistance, moldability, and mechanical properties.

[0036] Furthermore, among these PAS resins, a high molecular weight polymer with a substantially linear structure obtained by condensation polymerization from monomers mainly composed of bifunctional halogen aromatic compounds is particularly preferred. Note that the polyarylene sulfide resin used in this embodiment may be a mixture of two or more polyphenylene sulfide resins with different molecular weights.

[0037] In addition to linear polyphenylene sulfide resins, other examples include polymers in which a small amount of monomers such as polyhalo-aromatic compounds having three or more halogen substituents are used during condensation polymerization to form a partially branched or crosslinked structure, and polymers in which the melt viscosity is increased by oxidative crosslinking or thermal crosslinking by heating a low molecular weight linear polymer at high temperature in the presence of oxygen, thereby improving moldability.

[0038] (Polybutylene terephthalate resin) Polybutylene terephthalate resins (PBT resins) contain at least terephthalic acid or its ester-forming derivative (C 1-6The resin is obtained by polycondensation of a dicarboxylic acid component containing alkyl esters or acid halides (such as those of 1,4-butanediol) having at least 4 carbon atoms, or a glycol component containing an ester-forming derivative thereof (such as an acetylated compound). 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 preferably 30 meq / kg or less, and more preferably 25 meq / kg or less.

[0040] In PBT resin, dicarboxylic acid components (comonomer components) other than terephthalic acid and its ester-forming derivatives include, for example, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-dicarboxydiphenyl ether, etc. 8-14 Aromatic dicarboxylic acids; such as succinic acid, adipic acid, azelaic acid, sebacic acid, etc. 4-16 C alkanedicarboxylic acids; cyclohexanedicarboxylic acids, etc. 5-10 Cycloalkane dicarboxylic acids; ester-forming derivatives of these dicarboxylic acid components (C 1-6 Examples include alkyl ester derivatives and acid halides. These dicarboxylic acid components can be used individually or in combination of two or more.

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

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

[0043] Among these glycol components, C 2-6 alkylene glycols such as ethylene glycol, trimethylene glycol, polyoxyalkylene glycols such as diethylene glycol, or alicyclic diols such as cyclohexanedimethanol are more preferred.

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

[0045] The melt viscosity of the resin composition constituting the 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, the elastomer will be easier to stretch when it enters the recess interface region R described later. If it is 350 Pa·s or less, the resin 31 will be easier to enter the recess 21A, so that the stretched elastomer 32 can be present in the recess interface 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: Using a capillary rheometer ("Capillograph®" manufactured by Toyo Seiki Seisakusho Co., Ltd.), a 1 mmφ × 20 mmL flat die is used as the capillary, with a barrel temperature of 310°C and a shear rate of 1000 sec. -1 The melt viscosity is measured under the following conditions.

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

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

[0049] In addition to the melt viscosity characteristics mentioned above, the crystallization temperature characteristics are also considered to have an influence on the properties of the resin composition. When a resin composition with a low recrystallization temperature is used, its properties allow the resin to easily penetrate into depressions on the surface of the metal component, improving wettability. As a result, mechanical bonding due to the anchoring effect is exerted, and the adhesion at the interface between the component (especially the metal component) and the resin composition is further improved.

[0050] <Stretched elastomer> The stretched elastomer 32 is an elastomer whose aspect ratio (major axis / minor axis), which is the ratio of the major axis to the minor axis, is 1.5 or greater in the cross-section obtained when the composite molded product 10 is cut in the thickness direction of the resin molded product 30. In this specification, "minor axis" means the shortest diameter of the elastomer, and "major axis" means the longest diameter of the elastomer. The aspect ratio of the elastomer in the cross-section of the composite molded product can be determined from images acquired using a scanning electron microscope (SEM).

[0051] The stretched elastomer 32 has an aspect ratio of 1.5 or more, but it is preferable that the aspect ratio of the stretched elastomer 32 be between 5 and 30. If the aspect ratio is 5 or more, the stretched elastomer 32 will be layered, so airtightness can be ensured not only initially but also after the heat shock test, and if it is 30 or less, the elastomer will be maintained as a single shape in the stretched state. The lower limit of the aspect ratio of the stretched elastomer 32 is more preferably 8 or more, 11 or more, or 21 or more, and the upper limit is more preferably 28 or less, 25 or less, or 20 or less. For example, it is more preferable that the aspect ratio of the stretched elastomer 32 be between 8 and 30, between 10 and 25, or between 11 and 20.

[0052] At least a portion of the stretched elastomer 32 is located within the recess 21A in the above cross-section and is situated within the recess interface region R along the interface IF between the resin 31 and the surface roughening portion 21 in the resin 31. In this specification, "recess interface region" means the region located within the recess in the cross-section when the composite molded product is cut in the thickness direction of the composite molded product, 1 μm away from the interface between the resin and the surface roughening portion toward the interior of the resin, and sandwiched between a virtual line along this interface and the interface. In Figure 2, the recess interface region R is the region within the recess 21A that is 1 μm away from the interface IF between the resin 31 and the surface roughening portion 21 toward the interior of the resin 31, and sandwiched between a virtual line (dotted line) along the interface IF and the interface IF. At least a portion of the stretched elastomer 32 is located within the recess interface region R, but if a portion of the stretched elastomer 32 is located within the recess interface region R, the other portion of the stretched elastomer 32 may be located outside the recess interface region R. Figure 2 shows not only the stretched elastomer 32 in which the entirety is located within the recessed interface region R, but also the stretched elastomer 32 in which a portion is located within the recessed interface region R and the other portion is located outside the recessed interface region.

[0053] At least a portion of the stretched elastomer 32 located within the recessed interface region R is located along the interface IF. This arrangement of the stretched elastomer 32 allows it to mitigate stress and strain generated at the interface IF between the member 20 and the resin molded product 30, even when the composite molded product 10 expands or contracts due to a heat shock test. This prevents cracks and gaps from forming, thus ensuring good airtightness even after the heat shock test. In this specification, "at least a portion of the stretched elastomer is located 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 a degree that can be generally perceived as being along the interface.

[0054] In the above cross-section, it is sufficient for one stretched elastomer 32 to be present within the recessed interface region R, but it is preferable for two or more to be present. If two or more stretched elastomers 32 are present within the recessed interface region R, it is preferable that the average aspect ratio of the stretched elastomers 32 within the recessed interface region R is within the same range as the aspect ratio of the stretched elastomers 32 described above. For example, if five or more stretched elastomers are confirmed in the above cross-section, the average aspect ratio of the stretched elastomers is the average 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 outside the recess 21A.

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

[0057] The melt index (MI) of the elastomer, measured under conditions of 190°C and a load of 21N, is preferably between 1g / 10min and 10g / 10min. If the melt index (MI) of the elastomer is 1g / 10min or higher, the elastomer can be stretched, and if it is 10g / 10min or lower, it becomes easier to form the stretched elastomer 32 within the recessed 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 easily enter the recess 21A during the 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 by differential scanning calorimetry (DSC).

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

[0060] Olefin-based elastomers are copolymers containing ethylene and / or propylene as components. Specifically, examples include, but are not limited to, ethylene-propylene copolymers, ethylene-butene copolymers, ethylene-octene copolymers, ethylene-propylene-butene copolymers, ethylene-propylene-diene copolymers, ethylene-ethyl acrylate copolymers, ethylene-vinyl acetate copolymers, and ethylene-glycidyl methacrylate copolymers. However, epoxy group-containing olefin copolymers having reactive groups with inorganic fillers are most preferred.

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

[0062] [ka] In formula (1) above, R represents hydrogen or a lower alkyl group, and X represents one or more groups selected from -COOCH3, -COOC2H5, -COOC4H9, -COOCH2CH(C2H5)C4H9, -C6H5, and -CN.

[0063] As the α-olefin, C2-4 olefins such as ethylene and propylene can be used, with ethylene and propylene being preferred. As the α,β-unsaturated acid glycidyl ester, glycidyl acrylate and glycidyl methacrylate are preferred. In addition, 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 in the copolymer in the ranges of 30 mol% to 90 mol% and 70 mol% to 10 mol%, respectively, and the third component can be contained in the range of 0 mol% to 30 mol%.

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

[0066] Styrene-based elastomers include hard segments composed of styrene, α-methylstyrene, vinyltoluene, or other aromatic vinyl monomers, either alone or in copolymer form, and α-olefins (such as ethylene, propylene, 1-butene, 1-hexene, 1-octene, etc.). 2-12 Examples include block or graft copolymers (or hydrogenated versions thereof) of soft segments composed of at least one monomer selected from olefins, diene monomers (butadiene, isoprene, etc.), or other monomers, either alone or in copolymer form.

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

[0068] Examples of typical 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.) are introduced into these copolymers [epoxidized styrene-diene copolymers (epoxidized styrene-diene-styrene block copolymers or their hydrogenated polymers, etc.) in which the unsaturated bonds of the diene are epoxidized].

[0069] Silicone elastomers are elastomers that mainly contain organopolysiloxanes and are classified into polydimethylsiloxane-based, polymethylphenylsiloxane-based, and polydiphenylsiloxane-based types. Some of the organopolysiloxane may be modified with vinyl groups, alkoxy groups, etc. 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 elastomers include, but are not limited to, block copolymers in which aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate are used as the hard segment, and polyethers such as polyethylene glycol and polytetramethylene glycol, or aliphatic polyesters such as polyethylene adipate, polybutylene adipate, and polycaprolactone are used as the soft segment.

[0072] Examples of polyamide elastomers include, but are not limited to, block copolymers in which nylon 6, nylon 66, nylon 11, nylon 12, etc. are used as hard segments and polyethers or aliphatic polyesters are used as soft segments.

[0073] Examples of urethane-based elastomers include, but are not limited to, block copolymers in which a polyurethane 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 serves as the hard segment, and a polyether such as polyethylene glycol, polypropylene glycol, or polytetramethylene glycol, or an aliphatic polyester such as polyethylene adipate, polybutylene adipate, or polycaprolactone serves as the soft segment.

[0074] The stretched elastomer 32 is a reactive elastomer, and it is preferable that the reactive elastomer has glycidyl groups. Having glycidyl groups in the reactive elastomer enhances the adhesion between the metal member and the resin composition when the member 20 is a metal member. This is achieved through physical interactions with the metal member surface via van der Waals forces and the formation of chemical bonds through intermolecular forces between the metal member surface and functional groups formed on the metal member surface. Furthermore, when the member 20 is a metal member, the adhesion between the elastomer and the member 20 can be improved during the molding of the resin molded product 30. This makes it easier for the elastomer to stretch and form the stretched elastomer 32 when the resin composition fills the recess 21A.

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

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

[0077] Elastomer 33 is identical to stretched elastomer 32 except for its aspect ratio. Therefore, elastomer 33 has the same melting point and melt viscosity as described in the section on stretched elastomer 32.

[0078] <Inorganic fillers> Inorganic fillers are included to improve properties such as mechanical strength, heat resistance, dimensional stability (deformation resistance, warping), and electrical properties. Depending on the purpose, inorganic fillers can be used in the form of fibers, powders, or plates. Examples of fibrous fillers include glass fibers, asbestos fibers, carbon fibers, silica fibers, silica-alumina fibers, zirconia fibers, boron nitride fibers, boron fibers, potassium titanate fibers, and inorganic fibrous materials such as stainless steel, aluminum, titanium, copper, and brass. Particularly representative fibrous fillers are glass fibers and carbon fibers. On the other hand, examples of granular 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, and other materials such as 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, the use of glass fibers, calcium carbonate, glass beads, or a combination thereof is preferred. These inorganic fillers can be used individually or in combination of two or more.

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

[0080] The inventors of this invention have diligently researched the airtightness of composite molded products both initially and after heat shock testing, and have found that by placing a stretched elastomer along the interface within the recessed interface region, sufficient airtightness can be ensured not only initially but also after heat shock testing. Here, heat shock testing, also known as thermal shock testing, is a test in which a material is repeatedly subjected to rapid temperature changes, causing the material to expand and contract, generating thermal stress and thermal strain inside the material, and observing whether defects such as cracks occur in the material. In particular, the interface between the component and the resin molded product is a place where defects such as cracks are likely to occur and can be the starting point for a decrease in airtightness, so gas and liquid leakage is likely to occur from this interface. However, by placing at least a part of the stretched elastomer along the interface within the recessed interface region, even when the composite molded product expands and contracts due to heat shock testing, the stretched elastomer mitigates the stress and strain generated at the interface between the component and the resin molded product, preventing the formation of cracks and gaps, and thus ensuring good airtightness even after heat shock testing. According to this embodiment, since at least a portion of the stretched elastomer 32 is present within the recessed interface region R along the interface IF, sufficient airtightness can be ensured not only initially but also after the heat shock test.

[0081] <<<<Manufacturing method for composite molded products>>> First, a member 20 having a surface roughened portion 21 is prepared. The surface roughened portion 21 may be formed by laser processing to create metal clusters as described above, but it may also be formed by etching or blasting. For example, if the constituent material of the member 20 is metal and the surface roughened portion 21 is formed by laser processing, the member 20 having the surface roughened portion 21 can be formed as follows. When a laser is irradiated onto the member 20 made of metal, the metal on the surface of the member 20 melts due to the high-energy beam of the laser, is pushed out to the outside of the irradiated area, and then solidifies into a spherical shape due to surface tension. Spherical objects generated by laser scanning the surface of the member 20 at a minute pitch overlap, forming a metal cluster. Alternatively, the member 20 sublimes, and the scattered liquid metal particles solidify (re-adhere) and accumulate, forming a spherical metal cluster and thus forming the surface roughened 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 appropriately determined according to the metal material constituting the member 20. Furthermore, in order to make the molten metal extruded outside the laser irradiation area into tiny spheres, it is preferable to set the laser scanning pitch to 30 μm or less, and more preferably to 20 μm or less, or 10 μm or less.

[0083] The energy delivered to the metal surface per unit area per unit time is determined by the laser output and irradiation speed. Therefore, in addition to laser output, irradiation speed is also a factor in forming spherical metal clusters. The irradiation speed is preferably between 600 mm / s and 2000 mm / s. With appropriate laser output and irradiation speed, a localized, very short-duration temperature rise occurs on the metal surface, thereby forming spherical metal clusters. The irradiation speed is more preferably between 800 mm / s and 2000 mm / s, between 900 mm / s and 1800 mm / s, and even more preferably between 1000 mm / s and 1500 mm / s.

[0084] Furthermore, a resin composition containing an elastomer is prepared. When the resin composition is molded at a molding temperature above the melting point of the elastomer, so as to fill the recess 21A of a surface roughened portion 21 having a recess 21A in at least a part of the surface 20A of the member 20, the elastomer stretches within the recess interface region R located within the recess 21A and along the interface IF, forming a stretched elastomer 32 with an aspect ratio of 1.5 or more along the interface IF. Of the elastomer, the elastomer that did not stretch or stretched only slightly becomes elastomer 33. The reason for molding at a temperature above the melting point of the elastomer is that molding at a temperature above the melting point of the elastomer softens the elastomer, making it easier to stretch.

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

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

[0087] In the above insert molding, it is preferable to set the injection speed in the range of 15 mm / sec to 100 mm / sec. In insert molding, when molten resin is injected into the mold, it cools and solidifies into a solid layer (skin layer) upon contact with the mold wall. However, since the molten resin flows between the two solid layers (skin layers), a shear force is generated between the solid layer (skin layer) and the fluid layer. Thus, the shear force generated between the solid layer (skin layer) and the fluid layer causes the molecular chains to be stretched in the flow direction as they flow. Therefore, when the resin composition enters the recess 21A, the orientation of the molecular chains caused by the shear force makes it easier for the elastomer to form an elongated 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., but when the injection speed is 15 mm / sec to 100 mm / sec, the shear rate is estimated to be in the range of 100 (1 / sec) to 10000 (1 / sec). By performing insert molding under the above conditions, at least a portion of the stretched elastomer 32 can be formed within the recessed interface region R along the interface IF. [Examples]

[0088] To illustrate the present invention in detail, examples are given below, but the present invention is not limited to these descriptions. Figure 5A is a plan view of a composite molded product according to Example 4, Figure 5B is a cross-sectional view of Figure 5A, and Figure 6 is a schematic diagram of the test apparatus used in the airtightness test. Figure 7 is a scanning electron microscope image of the cross-section of the composite molded product according to Example 4 when it is cut in the thickness direction, and Figure 8 is a scanning electron microscope image of the cross-section of the composite molded product according to Comparative Example 2 when it is cut in the thickness direction. Figures 9A to 9E are schematic diagrams showing the process of preparing test pieces according to Reference Examples 1 to 5.

[0089] <Preparation of resin composition> First, the following resin composition was obtained by blending each component to achieve the composition shown below. (Resin composition 1) • Polyarylene sulfide resin 1 (manufactured by Polyplastics Co., Ltd., melt viscosity: 20 Pa·s (shear rate 1000 sec) -1 , temperature 310℃)): 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 (manufactured by Nippon Electric Glass Co., Ltd., "ECS03T747H"): 70.8 parts by mass Calcium carbonate 1 (Asahi Mining & Powder Co., Ltd. "MC-35W"): 47.2 parts by mass Pentaerythritol stearate (LOXYOL VPG861, manufactured by Emery Oleochemicals Japan): 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℃)): 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 (manufactured by Nippon Electric Glass Co., Ltd., "ECS03T747H"): 70.8 parts by mass Calcium carbonate 1 (Asahi Mining & Powder Co., Ltd. "MC-35W"): 47.2 parts by mass Pentaerythritol stearate (LOXYOL VPG861, manufactured by Emery Oleochemicals Japan): 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℃)): 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 (manufactured by Nippon Electric Glass Co., Ltd., "ECS03T747H"): 61.2 parts by mass Pentaerythritol stearate (LOXYOL VPG861, manufactured by Emery Oleochemicals Japan): 0.9 parts by mass • Carbon black (Mitsubishi Chemical Corporation "MA600B"): 0.3 parts by mass Antioxidant 1 (BASF Japan Ltd. "Irganox 1010"): 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℃)): 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℃): 57 parts by mass Reactive elastomer 3 (E group: 59.5% by weight, GMA group: 10.5% by weight, MA group: 0% by weight, melting point: 96.7°C): 14.2 parts by mass • Glass fiber 2 (manufactured by Nippon Electric Glass Co., Ltd., "ECS03T747"): 85.6 parts by mass Calcium carbonate 2 (manufactured by Toyo Fine Chemical Co., Ltd., Whiteon P-30): 36.7 parts by mass Pentaerythritol stearate (LOXYOL VPG861, manufactured by Emery Oleochemicals Japan): 1.0 parts by mass • Carbon black (Mitsubishi Chemical Corporation "MA600B"): 1.0 parts by mass • Antioxidant 2:0.5 parts by mass (BASF Japan Ltd.'s "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℃)): 100 parts by mass • Glass fiber 3 (Owens Corning Manufacturing Co., Ltd. "CS GL-HF"): 70.5 parts by mass Pentaerythritol stearate (LOXYOL VPG861, manufactured by Emery Oleochemicals Japan): 0.4 parts by mass • Carbon black (Mitsubishi Chemical Corporation "MA600B"): 0.9 parts by mass • Alkoxysilane compound (Shin-Etsu Chemical Co., Ltd. "KBE-903P"): 1.1 parts by mass

[0094] <Example 1> First, a copper component made of C1100 with a busbar shape, as shown in Figures 1A and 1B, measuring 88.0 mm in length, 20.1 mm in width, and 1.6 mm in thickness, was prepared. Then, using a fiber laser processing machine (ML-7350DL manufactured by Amada Weldtech Co., Ltd.), the front, back, and both sides of the copper component were irradiated with a laser under the conditions shown in Table 1, forming copper clusters in the center of each surface and creating a surface roughening area 5 mm wide. This resulted in the formation of a copper component with surface roughening areas on each surface.

[0095] Then, using the copper member as an insert member under the following conditions, insert molding was performed on the copper member having a surface roughened portion, using resin composition 1 to form a resin molded product on the surface of the copper member so that it had the shape shown in Figures 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 so as to cover the surface roughened portion. 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 Figure 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 Figure 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 Figure 1B) was 5.8 mm. • Injection molding machine: Sodick TR100EH Cylinder temperature: 330℃ • Mold temperature: 150℃ ·Injection speed: 70mm / s • Holding pressure: 50MPa ·Cooling time: 20sec

[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 product was obtained in the same manner as in Example 1, except that the laser output was changed to 19.5W and resin composition 2 was used instead of resin composition 1.

[0098] <Example 4> First, an annular aluminum member 61 made of A5052 aluminum, with an outer diameter of φ50 mm, an inner bore diameter of φ20 mm, and a thickness of 1 mm, was prepared as shown in Figures 5A and 5B. Then, using a fiber laser processing machine (Amada Weldtech ML-7350DL), a laser was irradiated concentrically onto the surface of the aluminum member 61 in the area from φ20 mm to φ26 mm (the bonding surface with the resin molded product 62 described later) under the conditions shown in Table 1, thereby forming aluminum clusters and creating a surface roughening area. This resulted in the formation of an aluminum member 61 having a surface roughening area on its surface.

[0099] Then, using the aluminum member 61 having a surface roughened portion as an insert member, insert molding was performed using the resin composition 3 under the following conditions, and a resin molded product was formed on the surface of the aluminum member 61 to have the shape shown in Figures 5A and 5B, thereby forming a composite molded product 60 consisting of the aluminum member 61 and the 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℃ • Mold temperature: 150℃ ·Injection speed: 15mm / s • Holding pressure: 50MPa ·Cooling time: 20sec

[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 product 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 article 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 the presence of stretched elastomers, etc., and calculation of the average aspect ratio> In the composite molded products of Examples 1-5 and Comparative Examples 1 and 2, a scanning electron microscope (Hitachi High-Tech Corporation's "SU5000") was used to observe the cross-section of the composite molded product to confirm whether at least a portion of the stretched elastomer is present along the copper member-resin molded product interface or the aluminum member-resin molded product interface within the recess interface region of copper clusters present in the surface roughened portion of the copper member or aluminum clusters present in the surface roughened portion of the aluminum member, and whether elastomer with an aspect ratio of 1 or more and less than 1.5 is present outside the recess interface region within the recess. Specifically, the composite molded product was cut in the thickness direction, and the cross-section was observed at a magnification of 10,000x to confirm the presence of stretched elastomer and elastomer with an aspect ratio of 1 or more and less than 1.5. Furthermore, if at least a portion of the stretched elastomer was confirmed to be present along the interface within the recess interface region, the short and long axes of the stretched elastomer were measured, the aspect ratio of the stretched elastomer was determined, and the average aspect ratio, which is the arithmetic mean, was calculated.

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

[0105] As shown in Figure 6, the test apparatus 70 was equipped with a chamber 71 that was sealed from the outside. A jig 72 and a composite molded product 80 were placed inside the chamber 71. The jig 72 was a bottomed rectangular parallelepiped, and the composite molded product 80 according to Examples 1-5 and Comparative Examples 1 and 2 was placed on top of the jig 72, sealing the inside of the jig 72 from the rest of the chamber 71. The valve 73 was opened and the inside of the jig 72 was evacuated by a vacuum pump 74, and then the valve 73 was closed and the chamber 71 was filled with helium gas by a helium cylinder 75. Helium gas leaking from the joint portion of the composite molded product 80 inside the chamber 71 was detected by a helium detector 76. The control device 77 displayed the helium gas detection results. The helium detector 76 used was a helium leak tester G-FINE manufactured by Cosmo Instruments Co., Ltd. and an L300i manufactured by Inficon Co., Ltd.

[0106] The helium pressure in chamber 71 was set to 400 kPa, and the vacuum pressure in jig 72 was set to 100 kPa. If the airtightness of the joint between the copper or aluminum component of the composite molded product 80 and the resin molded product was low, the helium gas in chamber 71 would flow into jig 72 and be detected by the helium detector 76. In this test, the helium pressure detected by the helium detector 76 (detection pressure) was 1.0 × 10⁻⁶. -7 Pa·m 3 If the value is greater than / s, it will be judged as poor airtightness, 1.0 × 10 -7 Pa·m 3 If the value was less than / s, it was judged to be good airtightness.

[0107] <Heat shock test> In the composite molded products of Examples 1 to 5 and Comparative Examples 1 and 2, a heat shock test was performed using the ES-106LH and ES-77LHS thermal shock testers manufactured by Hitachi Appliances, Ltd. The heat shock test consisted of 250 cycles, each consisting of 30 minutes of standing at -40°C followed by 30 minutes of standing at 150°C. After 250 cycles, the resin molded product was removed from the chamber and the airtightness test described above was performed to evaluate its resistance to thermal shock (heat shock resistance).

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

[0109] As shown in Table 1 and Figure 8, the composite molded articles of Comparative Examples 1 and 2 failed to achieve airtightness after the initial and heat shock tests because at least a portion of the stretched elastomer was not present within the recessed interface region. In Comparative Example 1, the presence of the stretched elastomer was not confirmed, so the average aspect ratio of the stretched elastomer in Comparative Example 1 was not measured. In contrast, as shown in Table 1 and Figure 7, the composite molded articles of Examples 1 to 5 showed high airtightness at the joints between the copper member and the polyarylene sulfide resin, and between the aluminum member and the polyarylene sulfide resin, even after the initial and heat shock tests, because at least a portion of the stretched elastomer was present within the recessed interface region along the copper member-resin molded article interface or the aluminum member-resin molded article interface. This confirmed that sufficient airtightness after the initial and heat shock tests can be obtained by ensuring that the stretched elastomer is present within the recessed interface region along the copper member-resin molded article interface or the aluminum member-resin molded article interface.

[0110] <Reference examples 1~5> To investigate the relationship between the melting point of the reactive elastomer and the average aspect ratio of the reactive elastomer after molding, sample pieces corresponding to Reference Examples 1 to 5 were prepared. First, resin compositions 1 to 4 were molded under the following conditions to obtain disc-shaped molded products with a diameter of 70 mm and a thickness of 3 mm, having a 30 μm thick flash (see Figure 9A). For simplicity, flash was formed on the molded product to reproduce the state in which resin compositions 1 to 4 had entered the surface roughened areas with recesses. (Molding conditions) • Molding machine: Toshiba Corporation EC60N i1.5A Cylinder temperature: 320℃ • Mold temperature: 150℃ ·Injection speed: 30mm / s • Holding pressure: Minimum filling pressure (the minimum pressure required for the cavity to be completely filled) + 5MPa ·Cooling time: 10sec

[0111] From the resulting molded product with burrs, a burr-containing portion with a length of 0.2 to 0.4 mm and a base width of 6 mm was cut out using a band saw (manufactured by YS Koki Co., Ltd.) (see Figure 9B), and the cut-out burr-containing portion was embedded in epoxy resin to protect it (see Figure 9C). Subsequently, the epoxy resin-embedded burr-containing portion was cut using a polishing machine (manufactured by Bühler Co., Ltd.) until the thickness of the burr-containing portion was reduced to about half, exposing the cross-section of the burr-containing portion (see Figure 9D). After that, the burr-containing portion with the exposed cross-section was cut out using a diamond cutter (manufactured by Bühler Co., Ltd.), fixed to a sample stage with hot wax (manufactured by Maruto Co., Ltd.), and the cross-section of the burr-containing portion was milled under the following conditions. (Cutting conditions) • Cutting machine: Hitachi High-Tech Corporation's ArBrade5000 • Pressure voltage: 3.4kV • Discharge voltage: 1.2kV • Cooling: None ·Processing time: 4.0h • Intermittent time: None

[0112] Then, the machined cross-section of the burr-containing portion was polished in that order with grits #400, #1000, and #2000 to obtain test pieces relating to Reference Examples 1 to 5 (see Figure 9E).

[0113] The burr-containing portions of the test specimens related to the obtained reference examples 1 to 5 were observed using SEM under the following conditions, and SEM observation images were obtained. (SEM observation conditions) ·Equipment: Phenom-World tabletop SEM-EDX Phenom Pro X ·Conditions: Backscattered electron image, 10kV • Magnification: 10,000x

[0114] Then, from the SEM observation images, five elastomer strands near the surface of the burr were randomly selected for each sample piece. The aspect ratio was calculated from the ratio of the major axis to the minor axis of each elastomer strand, and the average aspect ratio was obtained by arithmetic mean taking the calculated aspect ratios.

[0115] The results are shown in Table 2. In Table 2, "Ratio" refers to the ratio of the aspect ratio of the elastomer in the burrs in the test specimens for Reference Examples 1 to 4, with the aspect ratio of the elastomer in the burrs in the test specimen for Reference Example 5 being set to 1. [Table 2]

[0116] As shown in Table 2, the elastomer in the burrs of the specimens in Reference Examples 1 to 4 was more stretched than the elastomer in the burrs of the specimen in Reference Example 5. This is thought to be because the elastomer in the burrs of the specimen in Reference Example 5 had a melting point above 80°C, while the elastomer in the burrs of the specimens in Reference Examples 1 to 4 had a melting point below 80°C. From the results of Reference Examples 1 to 5, it is thought that a lower melting point of the elastomer makes it easier for at least a portion of the elastomer to penetrate into the recesses during the molding of the resin molded product, thus making it easier to form a stretched elastomer.

[0117] 10…Composite molded product 20... Components 20A…Surface 21...Surface roughening part 21A…recess 21B... protruding part 30…Resin molded product 31… Resin 32…Stretched elastomer 33… Elastomer IF…interface

Claims

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

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 resin composition, and the melt viscosity of the polyarylene sulfide resin composition is 50 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 in the manufacture of a composite molded article according to claim 1, It comprises a resin and an elastomer having an aspect ratio of 1 or more and less than 1.5, which is the ratio of the major axis to the minor axis. A resin composition in which, when molded at a molding temperature above the melting point of the elastomer, the resin composition enters into the recess of a surface roughened portion having recesses on at least a part of its surface, the elastomer stretches within the recess interface region located within the recess and along the interface between the member and the resin composition, forming a stretched elastomer with an aspect ratio of 1.5 or more along the interface.

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