JP7798968B2 - Polyamide resin composition for metal-resin bonding - Google Patents

Description

The present invention relates to a metal/resin composite structure, a method for manufacturing a metal/resin composite structure, and an engine mount member.

Technology for joining resin and metal components is in demand in a wide range of industrial fields, including automobiles, communications equipment, home appliances, and industrial machinery.

One technique proposed for joining resin and metal components is the so-called "injection joining" method, which involves injecting a resin material into a metal component inserted into a mold.

For example, a technique has been disclosed in which a resin material such as polybutylene terephthalate resin (hereinafter referred to as "PBT") or polyphenylene sulfide resin (hereinafter referred to as "PPS") is injection-bonded to a surface-roughened metal component (see, for example, Patent Document 1). Furthermore, by further developing metal surface roughening technology, a method has also been disclosed in which polyamide resins such as PA6 and PA66 are injection-molded onto a surface-roughened metal component (Patent Documents 2 to 4).

Japanese Patent Application Laid-Open No. 2004-216425 Japanese Patent Application Laid-Open No. 2006-315398 Japanese Patent Application Laid-Open No. 2007-182071 International Publication No. 2008/081933

However, the bonding strength of the composite structures of resin and metal members obtained using the methods disclosed in Patent Documents 2 to 4 was still not at a sufficient level.

For example, when conventional composite structures are applied to powertrain components that require high rigidity at high temperatures, such as engine mount brackets, which are components inside an automobile engine compartment and support the engine, the bonding strength at high temperatures is still not sufficient, leaving room for improvement.

The present invention was made in consideration of the above circumstances, and aims to provide a metal/resin composite structure in which a resin member made of a polyamide resin composition is firmly bonded and fixed to a metal member, a method for manufacturing the same, and an engine mount member.

The present invention relates to the following metal/resin composite structure, method for manufacturing a metal/resin composite structure, and engine mount member.

The metal/resin composite structure of the present invention is a metal/resin composite structure having a metal member having a textured surface and a resin member bonded to the textured surface of the metal member, wherein the resin member is made of a polyamide resin composition containing polyamide resin (A) and talc (B), wherein the polyamide resin (A) contains component units (a1) derived from a dicarboxylic acid and component units (a2) derived from a diamine, the component units (a1) derived from the dicarboxylic acid containing component units derived from terephthalic acid, and the component units (a2) derived from the diamine containing component units derived from a linear aliphatic diamine having 4 to 15 carbon atoms and component units derived from a branched aliphatic diamine having 4 to 18 carbon atoms, and the content of the talc (B) is 0.1 to 5 mass% of the polyamide resin composition.

The engine mount member of the present invention includes the metal/resin composite structure of the present invention.

The method for manufacturing a metal/resin composite structure of the present invention includes the steps of: 1) placing a metal member having a textured surface in an injection molding die; and 2) injecting the molten polyamide resin composition onto the surface of the metal member having the textured surface, allowing it to solidify, and bonding the resin member.

The present invention provides a metal/resin composite structure in which a resin member made of a polyamide resin composition is firmly bonded and fixed to a metal member, a method for manufacturing the same, and an engine mount member.

FIG. 1 is an external view schematically showing an example of the structure of the metal/resin composite structure of this embodiment. FIG. 2 is a schematic diagram showing a method for measuring ten-point roughness.

The present inventors have discovered that polyamide resin (A) containing component units derived from a branched aliphatic diamine exhibits good fluidity during molding. However, resin compositions containing such polyamide resins do not exhibit sufficient bonding strength with metal members having a textured structure.

In response to this, the present inventors have discovered that by combining talc (B) with polyamide resin (A) containing component units derived from branched aliphatic diamines, it is possible to significantly increase the bonding strength between metal and resin members while maintaining fluidity during molding.

The reason for this is not clear, but is presumed to be as follows.
That is, since polyamide resin (A) contains component units derived from branched aliphatic diamines, it exhibits good fluidity during molding, but its crystallization rate is slow. Therefore, it hardly crystallizes during injection molding, but tends to crystallize after injection molding. As a result, the amount of cure shrinkage on the metal member after injection molding is large, which tends to cause gaps at the interface between the metal member and the resin member, resulting in low bonding strength.
In contrast, by blending a predetermined amount of talc (B) with the polyamide resin (A), crystallization can be moderately promoted even during injection molding, thereby reducing the amount of cure shrinkage (on the metal member) after injection molding is completed, making it difficult for gaps to form at the interface between the metal member and the resin member, and increasing the bonding strength.

Furthermore, by further adding polyamide resin (C), which has a lower heat of fusion (ΔH) (crystallinity) than polyamide resin (A), it is possible to achieve a high level of balance between the fluidity and crystallization rate of the resin composition during injection molding. This makes it even less likely for gaps to form at the interface between the metal member and the resin member, further increasing the bonding strength.

Embodiments of the present invention will be described in detail below with reference to the drawings.

1. Metal/Resin Composite Structure FIG. 1 is an external view that schematically shows an example of the structure of a metal/resin composite structure 100 according to this embodiment.

As shown in FIG. 1, the metal/resin composite structure 100 according to this embodiment includes a metal member 110 having an uneven surface, and a resin member 120 joined to the metal member 110.

1-1. Metal member 110
The metal member 110 has a fine uneven structure on at least a part of the surface to be bonded to the resin member 120 .

(material)
The metal material constituting the metal member 110 is not particularly limited, but may be, for example, iron, high-tensile steel, stainless steel, aluminum, aluminum alloy, magnesium, magnesium alloy, copper, copper alloy, titanium, or titanium alloy. These may be used alone or in combination. Among them, from the viewpoint of light weight and high strength, aluminum (single aluminum) and aluminum alloy are preferred, and aluminum alloy is more preferred. Furthermore, from the viewpoint of high strength, iron and high-tensile steel are preferred. As aluminum alloys, alloy numbers 1050, 1100, 2014, 2024, 3003, 5052, 6061, 6063, and 7075 specified in JIS H4000 are preferably used.

The shape of the metal member 110 is not particularly limited as long as it can be bonded to the resin member 120, and may be, for example, a flat plate, curved plate, rod, cylinder, or block. The surface 111 to be bonded to the resin member 120 is not particularly limited, and may be either a flat surface or a curved surface.

It is preferable that the metal component 110 is formed into a predetermined shape by plastic processing such as cutting and pressing, punching, machining, polishing, electrical discharge machining, or other thinning processes, and then subjected to the roughening treatment described below. If the formed metal component 110 has been left in the open air for a long period of time and has developed an oxide film (rust) on its surface, it is preferable to remove this by polishing or chemical treatment.

(Uneven structure)
The metal member 110 preferably has a fine uneven structure including a plurality of protrusions on at least the surface 111 that contacts the resin member 120. This can improve the bonding strength between the metal member 110 and the resin member 120.

The center-to-center distance (pitch) of the multiple convex portions constituting the fine uneven structure need only be sufficient to bond the metal member 110 and the resin member 120 well. While not particularly limited, a distance of 5 nm to 500 μm is preferred. When the center-to-center distance of the multiple convex portions is 5 nm or greater, the recesses between the convex portions are appropriately large, allowing the polyamide resin composition to easily penetrate the recesses during bonding, further improving the bonding strength between the metal member 110 and the resin member 120. Furthermore, when the center-to-center distance of the multiple convex portions is 500 μm or less, the recesses are not too large, further preventing gaps from forming at the metal-resin interface of the metal/resin composite structure 100. This further prevents moisture and other contaminants from penetrating through the gaps at the metal-resin interface, further preventing a decrease in bonding strength when the metal/resin composite structure is used under high temperature and high humidity conditions. From the same perspective, the center-to-center distance of the multiple convex portions is more preferably 5 μm to 250 μm. The center-to-center distance between multiple protrusions is the average distance between the center of one protrusion and the center of an adjacent protrusion.

The center-to-center distance between the multiple protrusions can be measured by removing the resin member from the metal/resin composite structure by mechanical peeling, solvent cleaning, or the like, and observing the exposed surface of the metal member 110 using an electron microscope or laser microscope, or a surface roughness measuring device.

Specifically, a concave-convex structure in which the center-to-center distance between multiple convex portions is less than 0.5 μm can be observed using an electron microscope, while a concave-convex structure in which the center-to-center distance between multiple convex portions is 0.5 μm or more can be observed using a laser microscope or surface roughness measuring device. For example, in a photograph of the surface of the metal member 110 taken with an electron microscope or laser microscope, 50 convex portions are arbitrarily selected and the center-to-center distance between each of these convex portions is measured. All of the measured center-to-center distances between the convex portions are then added up and divided by 50 (average) to determine the "center-to-center distance between multiple convex portions."

The average ten-point mean roughness (Rz) of the surface 111 of the metal member 110 having a fine uneven structure over an evaluation length of 4 mm is not particularly limited, but is preferably greater than 2 μm, more preferably greater than 2 μm and not greater than 50 μm, and even more preferably greater than 2.5 μm and not greater than 45 μm.

The average value of the ten-point average roughness (Rz) can be measured in accordance with JIS B0601 (ISO 4287). Specifically, as described below, the ten-point average roughness (Rz) is measured on a total of six straight line sections: three arbitrary parallel straight line sections and three arbitrary perpendicular straight line sections, and the average of these is taken as the average Rz value (see Figure 2 described below).

The average length (RSm) of the roughness curve element of the surface 111 of the metal member 110, which has a fine uneven structure, is preferably 0.5 to 500 μm. In particular, from the perspective of bonding strength, it is preferable that the center-to-center distance between multiple convex portions is less than 0.5 μm and that the average length (RSm) of the roughness curve element is 0.5 to 500 μm. As described above, the average length of the roughness curve element can also be measured according to JIS B0601 (ISO 4287).

1-2. Resin member 120
The resin member 120 is a molded product of a polyamide resin composition.

The polyamide resin composition contains polyamide resin (A) and talc (B).

1-2-1. Polyamide resin (A)
The polyamide resin (A) contains a component unit (a1) derived from a dicarboxylic acid and a component unit (a2) derived from a diamine.

[Component unit (a1) derived from dicarboxylic acid]
The component unit (a1) derived from a dicarboxylic acid is not particularly limited, but from the viewpoint of facilitating an increase in crystallinity, it is preferable that the component unit (a1) contains a component unit derived from terephthalic acid.

The content of the component units derived from terephthalic acid is not particularly limited, but is preferably 20 to 100 mol % relative to the total number of moles of component units (a1) derived from dicarboxylic acids. A content of the above component units of 20 mol % or more tends to increase the crystallinity and mechanical strength of polyamide resin (A). From the same viewpoint, the content of the above component units is more preferably 50 to 100 mol %.

The dicarboxylic acid-derived component unit (a1) may further contain component units derived from dicarboxylic acids other than those mentioned above, provided that the effects of the present invention are not impaired. Examples of other dicarboxylic acids include aromatic dicarboxylic acids other than terephthalic acid (e.g., naphthalenedicarboxylic acid, isophthalic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid), and aliphatic dicarboxylic acids having 4 to 20 carbon atoms.

The total content of component units derived from other dicarboxylic acids (total content of component units derived from aromatic dicarboxylic acids other than terephthalic acid, component units derived from alicyclic dicarboxylic acids, and component units derived from aliphatic dicarboxylic acids having 4 to 20 carbon atoms) is preferably 0 to 80 mol %, more preferably 0 to 50 mol %.

[Diamine-derived component unit (a2)]
The diamine-derived component unit (a2) is not particularly limited, but from the viewpoint of increasing the fluidity during injection molding (to the extent that the mechanical strength of the resulting molded article is not impaired), it is preferable that the diamine-derived component unit (a2) contains a linear aliphatic diamine-derived component unit and a branched aliphatic diamine-derived component unit.

The linear aliphatic diamine is preferably a linear aliphatic diamine having 4 to 15 carbon atoms. Examples of linear aliphatic diamines having 4 to 15 carbon atoms include 1,4-butanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, and 1,10-decanediamine. Of these, 1,6-hexanediamine, 1,9-nonanediamine, and 1,10-decanediamine are preferred, with 1,6-hexanediamine being more preferred. These aliphatic diamines may be used alone or in combination.

The content of component units derived from linear aliphatic diamines is preferably 20 to 80 mol % of the total content of component units derived from linear aliphatic diamines and component units derived from branched aliphatic diamines. When the content of these component units is 20 mol % or more, the crystallization rate does not become too slow, making it easy to appropriately increase the crystallinity and mechanical strength of polyamide resin (A). When the content of these component units is 80 mol % or less, the crystallization rate of polyamide resin (A) does not become too high, making it less likely that fluidity will be impaired during molding. From the same perspective, the content of component units derived from linear aliphatic diamines is more preferably 30 to 60 mol % of the total content.

The branched aliphatic diamine is preferably a branched aliphatic diamine having 4 to 18 carbon atoms. Examples of branched aliphatic diamines having 4 to 18 carbon atoms include 2-methyl-1,5-pentanediamine, 2-methyl-1,8-octanediamine, 2-methyl-1,6-hexanediamine, 2-methyl-1,7-heptanediamine, 2-methyl-1,9-nonanediamine, and 2-methyl-1,10-decanediamine. Of these, 2-methyl-1,8-octanediamine and 2-methyl-1,5-pentanediamine are preferred, with 2-methyl-1,5-pentanediamine being more preferred. These aliphatic diamines may be used alone or in combination. For example, the diamine-derived component unit (a2) preferably includes at least one of a component unit derived from 2-methyl-1,8-octanediamine and a component unit derived from 2-methyl-1,5-pentanediamine.

The content of component units derived from branched aliphatic diamines is preferably 20 to 80 mol % of the total content of component units derived from linear aliphatic diamines and component units derived from branched aliphatic diamines. When the content of these component units is 20 mol % or more, the crystallization rate of polyamide resin (A) tends to be appropriately slowed, making it easier to improve fluidity during molding. When the content of these component units is 80 mol % or less, the crystallinity and mechanical strength of polyamide resin (A) are less likely to be impaired. From the same perspective, the content of component units derived from branched aliphatic diamines is more preferably 40 to 70 mol % of the total content.

The total of the component units derived from linear aliphatic diamines and the component units derived from branched aliphatic diamines is preferably 60 to 100 mol %, more preferably 70 to 100 mol %, and even more preferably 100 mol %, based on the total number of moles of component units (a2) derived from diamines.

The diamine-derived component units (a2) may further contain component units derived from other diamines, provided that the effects of the present invention are not impaired. Examples of other diamines include aromatic diamines and alicyclic diamines. The total content of component units derived from other diamines may be 5 mol % or less based on the total number of moles of diamine-derived component units (b).

Examples of such polyamide resins (A) include polyamide resins containing, as dicarboxylic acid-derived component units (a1), component units derived from terephthalic acid; and, as diamine-derived component units (a2), component units derived from 1,6-hexanediamine and component units derived from 2-methyl-1,5-pentanediamine or 2-methyl-1,8-octanediamine.

[Physical properties]
The heat of fusion (ΔH) of the polyamide resin (A) measured by a differential scanning calorimeter (DSC) is preferably higher than that of the polyamide resin (C) described below. Specifically, the heat of fusion (ΔH) of the polyamide resin (A) is preferably higher than 20 J/g. When the heat of fusion (ΔH) of the polyamide resin (A) is higher than 20 J/g, the crystallinity is not too low, and therefore the heat resistance is easily increased. From the same viewpoint, the heat of fusion (ΔH) of the polyamide resin (A) is more preferably 30 to 130 J/g.

The melting point (Tm) of polyamide resin (A) measured with a differential scanning calorimeter (DSC) is preferably 280 to 340°C. If the melting point (Tm) of polyamide resin (A) is 280°C or higher, mold releasability, mechanical strength, heat resistance, etc. are less likely to be impaired, and if it is 340°C or lower, there is no need to increase the molding temperature excessively, making it easier to achieve moldability. The melting point (Tm) of polyamide resin (A) is more preferably 290 to 320°C.

The glass transition temperature (Tg) of polyamide resin (A) measured with a differential scanning calorimeter (DSC) is preferably 70 to 170°C, and more preferably 128 to 155°C. When the glass transition temperature (Tg) of polyamide resin (A) is within the above range, heat resistance is less likely to be impaired.

The heat of fusion (ΔH), melting point (Tm) and glass transition temperature (Tg) of the polyamide resin (A) can be measured using a differential scanning calorimeter (DSC220C, manufactured by Seiko Instruments Inc.).
Specifically, approximately 5 mg of polyamide resin (A) is sealed in a measuring aluminum pan and heated from room temperature to 350°C at 10°C/min. To completely melt the resin, it is held at 350°C for 3 minutes and then cooled to 30°C at 10°C/min. After leaving it at 30°C for 5 minutes, it is heated a second time to 360°C at 10°C/min. The temperature (°C) of the endothermic peak during this second heating is taken as the melting point (Tm) of polyamide resin (A), and the inflection point corresponding to the glass transition is taken as the glass transition temperature (Tg). The heat of fusion (ΔH) is determined from the area of the exothermic peak of crystallization during the first heating process in accordance with JIS K7122.

The heat of fusion (ΔH), melting point (Tm), and glass transition temperature (Tg) of polyamide resin (A) can be adjusted by the composition of dicarboxylic acid and diamine.

The intrinsic viscosity [η] of polyamide resin (A), measured in 96.5% sulfuric acid at 25°C, is preferably 0.5 to 2.0 dl/g. When the intrinsic viscosity [η] of polyamide resin (A) is 0.5 dl/g or higher, the mechanical strength (toughness, etc.) of the resulting resin part (molded article) is easily increased, while when it is 2.0 dl/g or lower, fluidity during molding is less likely to be impaired. From the same perspective, the intrinsic viscosity [η] of polyamide resin is more preferably 0.80 to 1.15 dl/g. The intrinsic viscosity [η] can be adjusted by, for example, the amount of end-capping of polyamide resin (A).

The intrinsic viscosity of the polyamide resin (A) can be measured in accordance with JIS K6810-1977.
Specifically, 0.5 g of polyamide resin (A) is dissolved in 50 ml of 96.5% sulfuric acid solution to prepare a sample solution. The flow time of this sample solution is measured using an Ubbelohde viscometer at 25±0.05°C, and the obtained value is applied to the following formula to calculate the viscosity.
[η]=ηSP/[C(1+0.205ηSP)]

In the above formula, each algebra or variable represents:
[η]: Intrinsic viscosity (dl/g)
ηSP: specific viscosity C: sample concentration (g/dl)

ηSP is calculated by the following formula:
ηSP=(t-t0)/t0
t: number of seconds for the sample solution to flow down (seconds)
t0: Number of seconds (seconds) after blank sulfuric acid is flowed

From the viewpoint of thermal stability during compounding and molding, at least some of the molecular terminal groups of polyamide resin (A) may be capped with a terminal capping agent. For example, if the molecular terminal is a carboxyl group, the terminal capping agent is preferably a monoamine, and if the molecular terminal is an amino group, the terminal capping agent is preferably a monocarboxylic acid.

Examples of monoamines include aliphatic monoamines such as methylamine, ethylamine, propylamine, and butylamine; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; and aromatic monoamines such as aniline and toluidine. Examples of monocarboxylic acids include aliphatic monocarboxylic acids having 2 to 30 carbon atoms such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, oleic acid, and linoleic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; and alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid. The aromatic monocarboxylic acid and alicyclic monocarboxylic acid may have a substituent on the ring structure.

The content of polyamide resin (A) is preferably 20 to 99% by mass relative to the polyamide resin composition. When the content of polyamide resin (A) is 20% by mass or more, the properties of polyamide resin (A) are more easily obtained. From the same perspective, the content of polyamide resin (A) is more preferably 35 to 80% by mass relative to the polyamide resin composition.

1-2-2. Talc (B)
Talc (B) can appropriately increase the crystallization rate of the polyamide resin (A), thereby increasing the bonding strength between the metal member 110 and the resin member 120.

Talc (B) generally contains hydrous magnesium silicate (SiO ₂ : 58-64%, MgO: 28-32%, Al ₂ O ₃ : 0.5-5%, Fe ₂ O ₃ : 0.3-5%) as a main component.

The average particle size of talc (B) is not particularly limited, but is preferably 1 to 15 μm. When the average particle size of talc is within this range, it is easy to disperse in polyamide resin (A) without impairing the fluidity of the polyamide resin composition. From the same perspective, the average particle size of talc is more preferably 1 to 7.5 μm.

The average particle size of talc (B) can be measured by laser diffraction, for example, using a Shimadzu particle size distribution analyzer, Model SALD-2000A, manufactured by Shimadzu Corporation.

The content of talc (B) is preferably 0.1 to 5% by mass relative to the polyamide resin composition. A talc content of 0.1% by mass or more can moderately crystallize the polyamide resin (A) during injection molding, thereby further reducing the amount of cure shrinkage due to crystallization of the polyamide resin (A) after injection molding. This further reduces the likelihood of gaps forming between the surface 111 of the metal member 110 (specifically, between the multiple convex portions constituting the uneven structure) and the resin member 120, further enhancing bonding strength. A talc (B) content of 5% by mass or less prevents excessive crystallization of the polyamide resin (A) during injection molding, thereby preventing loss of fluidity and further suppressing poor conformability of the polyamide resin composition to the fine uneven structure of the surface 111 of the metal member 110 (poor filling between the multiple convex portions constituting the fine uneven structure). From the same perspective, the content of talc (B) is preferably 0.1 to 3.5% by mass relative to the polyamide resin composition.

The content of talc (B) is preferably 0.02 to 11 parts by mass, and more preferably 0.1 to 7 parts by mass, per 100 parts by mass of the total of polyamide resin (A) and talc (B).

1-2-3. Other Components The polyamide resin composition may further contain other components in addition to those described above, provided that the effects of the present invention are not impaired. Examples of other components include a polyamide resin (C) other than the polyamide resin (A), a fibrous inorganic filler (D), a lubricant (E), and other additives (e.g., colorants, antioxidants, heavy metal deactivators (chelating agents), flame retardant aids, ultraviolet absorbers, heat stabilizers, antistatic agents, antibacterial agents, antifogging agents, antiblocking agents, nucleating agents, dispersants, thickeners, foaming agents, pigments, dyes, organic fillers, etc.). Among these, a polyamide resin (C) other than the polyamide resin (A), a fibrous inorganic filler (D), and a lubricant (E) are preferred.

(Polyamide resin (C))
The heat of fusion (ΔH) of the polyamide resin (C) is preferably lower than the heat of fusion (ΔH) of the polyamide resin (A). Specifically, the heat of fusion (ΔH) of the polyamide resin (C) measured by a differential scanning calorimeter (DSC) is preferably 0 to 5 J/g. When the heat of fusion (ΔH) of the polyamide resin (C) is 5 J/g or less, the crystallinity of the resin composition can be reduced, thereby further reducing the amount of cure shrinkage on the metal member 110 and making it easier to further increase the bonding strength with the metal member 110. From the same viewpoint, the heat of fusion (ΔH) of the polyamide resin (C) is more preferably 0 J/g. Furthermore, the polyamide resin (C) is preferably an amorphous resin.

The difference in the heat of fusion (ΔH) between polyamide resin (C) and polyamide resin (A) is not particularly limited, but is preferably 20 J/g or more. A difference in the heat of fusion (ΔH) of 20 J/g or more makes it easier to adjust the crystallization rate of the polyamide resin composition during injection molding. From the same perspective, the difference in the heat of fusion (ΔH) between polyamide resin (C) and polyamide resin (A) is more preferably 30 to 130 J/g, and even more preferably 30 to 60 J/g. The heat of fusion (ΔH) of polyamide resin (C) can be measured using the same method as described above.

Polyamide resin (C) is not particularly limited as long as its heat of fusion (ΔH) satisfies the above range, but it contains component units (c1) derived from a dicarboxylic acid and component units (c2) derived from a diamine.

[Component unit (c1) derived from dicarboxylic acid]
The component unit (c1) derived from a dicarboxylic acid is not particularly limited, but from the viewpoint of adjusting the crystallinity, it is preferable that the component unit (c1) contains a component unit derived from isophthalic acid.

The content of the component units derived from isophthalic acid is not particularly limited, but is preferably 20 to 100 mol % relative to the total number of moles of component units (c1) derived from dicarboxylic acids. A content of the above component units of 20 mol % or more tends to increase the crystallinity of polyamide resin (A). From the same perspective, the content of the above component units is more preferably 50 to 100 mol %.

The dicarboxylic acid-derived component units (c1) may further contain component units derived from dicarboxylic acids other than those mentioned above. Examples of other dicarboxylic acids include aromatic dicarboxylic acids other than isophthalic acid (e.g., terephthalic acid), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid), and aliphatic dicarboxylic acids having 4 to 20 carbon atoms. Among these, terephthalic acid is preferred from the viewpoint of its good affinity with the polyamide resin (A).

The molar ratio of isophthalic acid-derived component units to terephthalic acid-derived component units in dicarboxylic acid-derived component units (c) is preferably isophthalic acid-derived component units/terephthalic acid-derived component units = 60/40 to 100/0. By appropriately lowering the crystallization rate of polyamide resin (C), it is possible to adjust the balance between fluidity and crystallization rate during molding when combined with polyamide resin (A).

Furthermore, the content of component units derived from isophthalic acid in component units (c1) derived from dicarboxylic acid constituting polyamide resin (C) is preferably greater than the content of component units derived from isophthalic acid in component units (a1) derived from dicarboxylic acid constituting polyamide resin (A).

The total content of component units derived from other dicarboxylic acids is preferably 0 to 80 mol%, and more preferably 0 to 50 mol%.

[Diamine-derived component unit (c2)]
The diamine-derived component unit (c2) is not particularly limited, but preferably contains an aliphatic diamine-derived component unit.

The aliphatic diamine is preferably an aliphatic diamine having 4 to 15 carbon atoms. From the viewpoint of appropriately adjusting the crystallization rate when combined with polyamide resin (A), the aliphatic diamine having 4 to 15 carbon atoms is preferably a linear aliphatic diamine. The linear aliphatic diamine is the same as described above, and is preferably 1,6-hexanediamine. Note that the diamine-derived component unit (c2) does not necessarily have to contain a branched aliphatic diamine-derived component unit.

The content of the component units derived from linear aliphatic diamines is preferably 40 to 100 mol % relative to the total number of moles of component units (c2) derived from diamines. A content of 40 mol % or more of these component units tends to slow the crystallization rate, while a content of 100 mol % or less tends to maintain heat resistance. From the same perspective, the content of these component units is more preferably 60 to 100 mol % relative to the total number of moles of component units (c2) derived from diamines.

[Physical properties]
Since the polyamide resin (C) is an amorphous resin, the melting point (Tm) is not observed.

The glass transition temperature (Tg) of polyamide resin (C) is not particularly limited, but is preferably the same as the glass transition temperature (Tg) of polyamide resin (A), and may be, for example, 90 to 130°C.

The intrinsic viscosity [η] of polyamide resin (C) is not particularly limited, but is lower than the intrinsic viscosity [η] of polyamide resin (A), for example, 0.50 to 1.50 dl/g, preferably 0.50 to 0.90 dl/g.

The melting point (Tm), glass transition temperature (Tg), and intrinsic viscosity [η] can be measured using the same methods as described above.

The content of polyamide resin (C) is not particularly limited, but can be 0 to 30% by mass relative to the polyamide resin composition. If the content of polyamide resin (C) is above a certain amount, the crystallization rate tends to slow, while if it is 30% by mass or less, heat resistance is less likely to be impaired. From a similar perspective, the content of polyamide resin (C) can be 0 to 20% by mass relative to the polyamide resin composition.

The content of polyamide resin (C) can be 0 to 60% by mass relative to the total of polyamide resin (C) and polyamide resin (A). When the content of polyamide resin (C) is a certain amount or more, the crystallinity of the resin composition can be reduced, and the amount of cure shrinkage on the metal member 110 during injection molding can also be further reduced. When the content of polyamide resin (C) is 60% by mass or less, the crystallinity of the resulting resin composition is less likely to be impaired, and the mechanical strength and heat resistance of the molded product are less likely to be impaired. From the same perspective, the content of polyamide resin (C) can be more preferably 1 to 40% by mass, and even more preferably 5 to 40% by mass, relative to the total of polyamide resin (C) and polyamide resin (A).

(Fiber-like inorganic filler (D))
The fibrous inorganic filler (D) can impart high mechanical strength to the resin member 120, which is a molded product of the polyamide resin composition.

Examples of fibrous inorganic fillers (D) include glass fiber, carbon fiber, wollastonite, potassium titanate whiskers, calcium carbonate whiskers, aluminum borate whiskers, magnesium sulfate whiskers, zinc oxide whiskers, milled fiber, and cut fiber. One of these may be used alone, or two or more may be used in combination. Among these, glass fiber and wollastonite are preferred, with glass fiber being more preferred, as they tend to increase the mechanical strength of the resin member 120.

The average fiber length of the fibrous inorganic filler (D) can be, for example, 1 μm to 20 mm, preferably 5 μm to 10 mm, from the viewpoints of the moldability of the resin composition and the mechanical strength and heat resistance of the resulting molded body. The aspect ratio of the fibrous inorganic filler (D) can be, for example, 5 to 2000, preferably 30 to 600.

The average fiber length and average fiber diameter of the fibrous inorganic filler (D) can be measured by the following method.
1) The resin composition is dissolved in a hexafluoroisopropanol/chloroform solution (0.1/0.9% by volume), and then filtered to obtain a filtrate.
2) The filtered material obtained in 1) is dispersed in water, and the fiber length (Li) and fiber diameter (di) of each of 300 randomly selected fibers are measured using an optical microscope (magnification: 50x). The number of fibers with a fiber length of Li is designated as qi, and the weight-average length (Lw) is calculated based on the following formula, which is the average fiber length of the fibrous filler.
Weight average length (Lw) = (Σqi × Li ² ) / (Σqi × Li)
Similarly, the number of fibers having a fiber diameter Di is taken as ri, and the weight average diameter (Dw) is calculated based on the following formula, and this is taken as the average fiber diameter of the fibrous filler.
Weight average diameter (Dw) = (Σri×Di ² )/(Σri×Di)

The content of the fibrous inorganic filler (D) is not particularly limited, but is preferably 0 to 75% by mass, more preferably more than 0% by mass and not more than 75% by mass, and even more preferably 15 to 60% by mass, relative to the polyamide resin composition.

(Lubricant (E))
The lubricant (E) can improve the flowability and kneading processability of the polyamide resin composition during molding, and the releasability from a mold.

The lubricant (E) is not particularly limited, but is typically a metal salt of a medium-chain fatty acid having 8 to 10 carbon atoms or a long-chain fatty acid having 12 or more carbon atoms.

Examples of fatty acids include octylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, behenic acid, montanic acid, sebacic acid, and ricinoleic acid, with montanic acid, 12-hydroxystearic acid, and behenic acid being preferred.

Examples of metal salts include lithium salts, sodium salts, potassium salts, magnesium salts, calcium salts, barium salts, zinc salts and aluminum salts, with calcium salts, magnesium salts, zinc salts, aluminum salts and lithium salts being preferred.

Examples of metal salts of such fatty acids include calcium 12-hydroxystearate, zinc 12-hydroxystearate, magnesium 12-hydroxystearate, aluminum 12-hydroxystearate, lithium 12-hydroxystearate, calcium behenate, zinc behenate, magnesium behenate, lithium behenate, calcium montanate, zinc montanate, magnesium montanate, aluminum montanate, and lithium montanate. These can be used alone or in combination of two or more.

The content of lubricant (E) is, for example, 0 to 10% by mass, and preferably 0.1 to 8% by mass, relative to the polyamide resin composition. When the content of lubricant (E) is above a certain level, fluidity is improved and kneading and moldability are likely to be improved. When the content is below a certain level, the kneading processability of the resin composition is less likely to be impaired.

When two or more lubricants (E) are included, the content of the metal montanate salt in the total lubricant (E) is 20 to 100% by mass, preferably 30 to 100% by mass, and more preferably 50 to 100% by mass. This can increase the bonding strength of the metal/resin composite structure.

(Physical Properties of Polyamide Resin Composition)
The injection flow length (L/t) of the polyamide resin composition varies depending on the composition, but is preferably 18 mm or more, and more preferably 20 to 30 mm. When the flow length (L/t) is at least a certain level, the composition has excellent fluidity, and therefore, when joined to the metal member 110, the polyamide resin composition is easily filled without gaps between the convex portions of the uneven structure on the surface 111 of the metal member 100. The flow length can be measured by injection molding using a bar flow mold.

The flow length of the polyamide resin composition can be adjusted by the composition and content ratio of polyamide resins (A) and (C), the content of talc (B) and fibrous inorganic filler (D), etc. In order to increase the flow length, it is preferable to increase the content of branched aliphatic diamine in polyamide resin (A) or add polyamide resin (C), for example.

(Method for producing polyamide resin composition)
The polyamide resin composition can be produced by a known resin kneading method, for example, by mixing the above-mentioned components in a Henschel mixer, V blender, ribbon blender, or tumbler blender, or by mixing and then melt-kneading the components in a single-screw extruder, multi-screw extruder, kneader, or Banbury mixer, followed by granulation or pulverization.

1-3. Physical Properties The metal/resin composite structure 100 according to the present embodiment includes a metal member 110 having a fine uneven structure on its surface, and a resin member 120 made of a polyamide resin composition firmly bonded to the surface having the fine uneven structure.

Specifically, the tensile shear strength of the joint surface between the metal member 110 and the resin member 120 is preferably 40 MPa or more, more preferably 45 MPa or more, and even more preferably 47 to 70 MPa.

Furthermore, it is preferable that the fracture surface after measuring the tensile shear strength exhibits a base material fracture morphology. Base material fracture is defined as a fracture morphology in which residual resin is observed over 80% or more of the area of the interface at the metal/resin joint.

Bond strength can be measured using a tensile test under the following conditions: 23°C, 60 mm chuck distance, and 10 mm/min tensile speed. Specifically, a special jig is attached to a tensile tester, and the breaking load (N) of the metal/resin composite structure is measured under the above conditions. The breaking load (N) is then divided by the area of the metal/resin bonded portion to calculate the bond strength (tensile shear strength) (MPa).

The bond strength can be adjusted by the composition of the polyamide resin composition, particularly the type and content of polyamide resin (A), talc (B), and polyamide resin (C). To increase the bond strength, it is preferable to adjust the composition so that the fluidity during injection molding is increased while also achieving appropriate crystallization during injection molding. From the perspective of achieving appropriate crystallization during injection molding, it is preferable to increase the content of talc (B) appropriately. From the perspective of increasing fluidity, it is preferable to increase the content of branched aliphatic diamine in polyamide resin (A) or add polyamide resin (C).

2. Manufacturing Method of Metal/Resin Composite Structure The manufacturing method of the metal/resin composite structure 100 according to the present embodiment is not particularly limited, but may include, for example, 1) a step of placing a metal member 110 having a concave-convex structure on its surface in an injection molding die, and 2) a step of injecting a molten polyamide resin composition onto the surface of the metal member 110 having the concave-convex structure, allowing it to solidify, and joining a resin member 120 to the surface.

Regarding step 1), first, a metal member 110 having an uneven structure on at least a portion of its surface is prepared.

The method for obtaining the metal member 110 having a fine uneven structure is not particularly limited, and examples thereof include a method using laser processing as disclosed in Japanese Patent No. 4020957; a method of immersing a metal member in an aqueous inorganic base solution such as NaOH and / or an aqueous inorganic acid solution such as HCl or HNO ₃ ; a method of treating a metal member by an anodic oxidation method as disclosed in Japanese Patent No. 4541153; a displacement crystallization method in which etching is performed with an acid-based etching agent as disclosed in International Publication No. 2015-8847, preferably an acid-based etching agent aqueous solution containing an inorganic acid, ferric ions, cupric ions, and optionally manganese ions, aluminum chloride hexahydrate, sodium chloride, etc.; a method of immersing a metal member in an aqueous solution of one or more selected from hydrazine hydrate, ammonia, and water-soluble amine compounds as disclosed in International Publication No. 2009/31632 (hereinafter, sometimes referred to as the NMT method), and a hot water treatment method as disclosed in Japanese Patent Laid-Open No. 2008-162115.

These methods can be selected arbitrarily depending on the type of metal used and the distance between the centers of the multiple protrusions. However, from the perspective of the bonding strength between the metal member 110 and the resin member 120, the replacement crystallization method and the NMT method are preferred in this embodiment.

Then, the mold is opened and the prepared metal member 110 with the concave-convex structure is placed in the cavity (space) within the mold.

Regarding step 2), the polyamide resin composition is injected into the cavity of the mold so that at least a portion of the polyamide resin composition contacts the surface having the fine uneven structure of the metal member 110. Thereafter, the polyamide resin composition is cooled and solidified, thereby joining the metal member 110 and the resin member 120 together.

The temperature of the injection molding mold is not particularly limited as long as it can melt the polyamide resin composition to a state suitable for injection molding, but can be, for example, 100 to 250°C.

After injection and pressure holding, the mold is cooled, then opened and ejected using an ejector pin if necessary, to obtain the metal/resin composite structure 100.

The mold may be a known injection molding mold, such as a mold for high speed heat cycle molding (RHCM, heat & cool molding) or a core-back mold for foam molding.

3. Uses of Metal/Resin Composite Structure The metal/resin composite structure 100 according to the present embodiment has high productivity and a high degree of freedom in shape control, and therefore can be deployed in a variety of uses.

Furthermore, the metal/resin composite structure 100 according to this embodiment has high heat resistance, mechanical properties, friction resistance, sliding properties, airtightness, and watertightness, making it suitable for use in applications that suit these properties.

Examples of such applications include vehicle structural parts, vehicle mounted items, electronic device housings, home appliance housings, structural parts, machine parts, various automotive parts, electronic device parts, household goods applications such as furniture and kitchenware, medical equipment, building material parts, and other structural and exterior parts.

Specific examples include the following parts, designed to use metal to support areas where resin alone is not strong enough. In the vehicle industry, these include instrument panels, console boxes, door handles, door trim, shift levers, pedals, glove boxes, bumpers, hoods, fenders, trunks, doors, roofs, pillars, seats, steering wheels, ECU boxes, electrical components, engine peripherals, drivetrain and gear peripherals, intake and exhaust system parts, and cooling system parts. In addition, examples of building materials and furniture include glass window frames, handrails, curtain rails, dressers, drawers, closets, bookshelves, desks, and chairs. Examples of precision electronic components include connectors, relays, and gears. Examples of transport containers include shipping containers, suitcases, and trunks.

Furthermore, by combining the high thermal conductivity of the metal member 110 with the insulating properties of the resin member 120, it can be used in components for equipment that requires optimal heat management design, such as various home appliances. Specific examples include home appliances such as refrigerators, washing machines, vacuum cleaners, microwave ovens, air conditioners, lighting equipment, electric water heaters, televisions, clocks, ventilation fans, projectors, and speakers, as well as electronic information devices such as personal computers, mobile phones, smartphones, digital cameras, tablet PCs, portable music players, portable game consoles, chargers, and batteries.

Other uses include toys, sports equipment, shoes, sandals, bags, tableware such as forks, knives, spoons, and plates, stationery such as ballpoint pens, mechanical pencils, files, and binders, cooking utensils such as frying pans, pots, kettles, spatulas, ladles, slotted ladles, whisks, and tongs, parts for lithium-ion secondary batteries, and robots.

In addition, the metal/resin composite structure 100 according to this embodiment has excellent mechanical properties and wear resistance because the resin member 120 contains polyamide. This makes it extremely useful as a sliding part for dynamic applications such as gears, bushings, and door checker arms.

The metal/resin composite structure 100 according to this embodiment is also useful as a bracket constituting an engine mount member that supports an engine (vibration member) on a support member in a vibration-damping manner. An engine mount member in which a polyamide resin composition is integrally molded into an insert fastener formed on the bracket for fixing the vibrating member and/or support member, or into a metal reinforcing rib embedded in the bracket body for increased strength, is obtained by forming a finely textured surface on the surface of the fastener or the metal reinforcing rib, and then insert molding the polyamide resin composition. The engine mount member according to this embodiment has a bracket that exhibits high bonding strength and heat resistance, and also has high vibration characteristics, so it can effectively withstand vibrations from an engine, etc.

The present invention will be described below with reference to examples. The scope of the present invention should not be construed as being limited by these examples.

1. Metallic member <Preparation of surface-treated metallic member (M-1)>
An aluminum plate (thickness: 2.0 mm) of alloy number 6063 specified in JIS H4000 was cut into a length of 45 mm and a width of 18 mm. This aluminum plate was immersed in an alkaline etching agent (15% by mass of sodium hydroxide, 3% by mass of zinc oxide) at 30°C for 3 minutes (hereinafter sometimes abbreviated as "alkaline etching agent treatment"), and then immersed in 30% by mass of nitric acid at 30°C for 1 minute. This alkaline etching agent treatment was repeated once more. Next, the resulting aluminum alloy plate was immersed in an acid etching agent (4.1% by mass of sulfuric acid, 3.9% by mass of ferric chloride, 0.2% by mass of cupric chloride) at 30°C for 5 minutes and etched by shaking. Next, ultrasonic cleaning was performed in running water (in water for 1 minute) and dried to obtain a surface-treated metal member (M-1).

The surface properties of the obtained surface-treated metal member (M-1) were as follows:
Center-to-center distance of multiple convex portions: 95 μm
Average element length Rsm: 104 μm
Rz of six straight line sections: 19.2 μm, 20.8 μm, 18.5 μm, 18.2 μm, 18.4 μm, 19.6 μm
Average Rz value: 19 μm
Etching rate: 2.9% by mass

<Preparation of Surface-Treated Metal Member (M-2)>
An aluminum plate in which alloy number A6063 was changed to alloy number A5052 was etched by immersing it in an acid etching agent (sulfuric acid: 8.2 mass%, ferric chloride: 7.8 mass% (Fe ³⁺ : 2.7 mass%), cupric chloride: 0.4 mass% (Cu ²⁺ : 0.2 mass%), ion-exchanged water: balance) at 30°C for 80 seconds and shaking it. The plate was then ultrasonically cleaned in running water (in water for 1 minute) and dried to obtain a surface-treated metal member (M-2).

The surface properties of the obtained surface-treated metal member (M-2) were as follows:
Center-to-center distance of multiple convex portions: 92 μm
Average element length Rsm: 96.8 μm
Rz of six straight line sections: 17.8 μm, 18.1 μm, 19.6 μm, 17.8 μm, 17.2 μm, 18.0 μm
Average Rz value: 18.1 μm
Etching rate: 2.6% by mass

The surface properties of the surface-treated metal parts (center-to-center distance between multiple convex portions and surface roughness) were measured using the following methods.

(Center-to-center distance of multiple protrusions)
The interval period of the surface-treated metal member was measured using a laser microscope (VK-X100 manufactured by KEYENCE Corporation). Specifically, 50 randomly selected convex portions were selected from a photograph taken of the surface of the metal member, and the center-to-center distance between adjacent convex portions was measured. All the measured center-to-center distances were added up and divided by 50 to obtain the "center-to-center distance between multiple convex portions."

(surface roughness)
The surface roughness of the surface-treated metal member was measured using a surface roughness measuring device "Surfcom 1400D (manufactured by Tokyo Seimitsu Co., Ltd.)," and the etching rate was calculated from the ten-point average roughness (Rz) on the six straight lines shown in Figure 2, the average element length (Rsm), and the mass ratio of the metal member before and after the etching treatment.
The measurement conditions were as follows:
・Stylus tip radius: 5μm
Reference length: 0.8 mm
Evaluation length: 4 mm
・Measurement speed: 0.06mm/sec
Measurements were taken on a total of six straight lines on the surface of the metal member, including three arbitrary parallel lines and three arbitrary perpendicular lines to these lines, and the average value was calculated (see Figure 2).

2. Constituents of Polyamide Resin Composition (1) Polyamide Resin <Polyamide Resin (PA-1)>
1,312 g (11.3 mol) of 1,6-hexanediamine, 1,312 g (11.3 mol) of 2-methyl-1,5-pentanediamine, 3,655 g (22.0 mol) of terephthalic acid, 5.5 g (5.2 × ¹⁰ mol) of sodium hypophosphite as a catalyst, and 640 ml of ion-exchanged water were charged into a 1-liter reactor. After purging with nitrogen, ^the mixture was reacted for 1 hour at 250°C and 35 kg/cm². The molar ratio of 1,6-hexanediamine to 2-methyl-1,5-pentanediamine was 50:50. After 1 hour, the reaction product produced in the reactor was withdrawn into a receiver connected to the reactor and set at a pressure approximately 10 kg/ ^cm² lower, yielding a polyamide precursor with an intrinsic viscosity [η] of 0.15 dL/g. Next, this polyamide precursor was dried and then melt-polymerized using a twin-screw extruder at a cylinder set temperature of 330° C. to obtain a polyamide resin (PA-1).

The composition of the resulting polyamide resin (PA-1) was as follows: Among the dicarboxylic acid-derived component units, the content of component units derived from terephthalic acid was 100 mol %; among the diamine-derived component units, the content of component units derived from 1,6-hexanediamine was 50 mol %; and the content of component units derived from 2-methyl-1,5-pentanediamine was 50 mol %. Furthermore, the polyamide resin (PA-1) had an intrinsic viscosity [η] of 0.9 dl/g, a melting point Tm of 300°C, a glass transition temperature of 140°C, and a heat of fusion (ΔH) of 45 J/g.

<Polyamide resin (PA-2)>
2,800 g (24.1 mol) of 1,6-hexanediamine, 1,390 g (8.4 mol) of terephthalic acid, 2,581 g (15.5 mol) of isophthalic acid, 109.5 g (0.9 mol) of benzoic acid, 5.7 g of sodium hypophosphite monohydrate, and 545 g of distilled water were placed in a 13.6 L autoclave and purged with nitrogen. Stirring was started at 190 ° C, and the internal temperature was raised to 250 ° C over 3 hours. At this time, the internal pressure of the autoclave was raised to 3.02 MPa. After continuing the reaction for 1 hour, the low-order condensate was discharged to the atmosphere through a spray nozzle installed at the bottom of the autoclave and extracted. Thereafter, the low-order condensate was cooled to room temperature, pulverized in a pulverizer to a particle size of 1.5 mm or less, and dried at 110 ° C for 24 hours. The water content of the obtained low-order condensate was 3,000 ppm, and the intrinsic viscosity [η] was 0.14 dl/g. Next, this low-order condensate was melt-polymerized in a twin-screw extruder having a screw diameter of 30 mm and an L/D ratio of 36 at a barrel setting temperature of 330°C, a screw rotation speed of 200 rpm, and a resin supply rate of 6 kg/h to obtain a polyamide resin (PA-2).

The composition of the resulting polyamide resin (PA-2) was as follows: Among the dicarboxylic acid-derived component units, the content of component units derived from terephthalic acid was 70 mol %, and the content of component units derived from isophthalic acid was 30 mol %; among the diamine-derived component units, the content of component units derived from 1,6-hexanediamine was 100 mol %. Furthermore, the polyamide resin (PA-2) had an intrinsic viscosity [η] of 0.9 dl/g, a melting point (Tm) of 330°C, a glass transition temperature (Tg) of 125°C, and a heat of fusion (ΔH) of 50 J/g.

<Polyamide resin (PA-3)>
2,800 g (24.1 mol) of 1,6-hexanediamine, 2,581 g (15.5 mol) of terephthalic acid, 1,390 g (8.4 mol) of isophthalic acid, 109.5 g (0.9 mol) of benzoic acid, 5.7 g of sodium hypophosphite monohydrate, and 545 g of distilled water were placed in an autoclave with a capacity of 13.6 L and purged with nitrogen. Stirring was started at 190 ° C, and the internal temperature was raised to 250 ° C over 3 hours. At this time, the internal pressure of the autoclave was raised to 3.02 MPa. After continuing the reaction for 1 hour, the low-order condensate was discharged to the atmosphere from a spray nozzle installed at the bottom of the autoclave and extracted. Thereafter, the low-order condensate was cooled to room temperature, pulverized in a pulverizer to a particle size of 1.5 mm or less, and dried at 110 ° C for 24 hours. The resulting low-order condensate had a water content of 3,000 ppm and an intrinsic viscosity [η] of 0.14 dl/g.
Next, this low-order condensate was melt-polymerized in a twin-screw extruder having a screw diameter of 30 mm and an L/D ratio of 36 at a barrel setting temperature of 330°C, a screw rotation speed of 200 rpm, and a resin supply rate of 6 kg/h to obtain a polyamide resin (PA-3).

The composition of the resulting polyamide resin (PA-3) was as follows: Among the dicarboxylic acid-derived component units, the content of component units derived from terephthalic acid was 30 mol %, and the content of component units derived from isophthalic acid was 70 mol %; among the diamine-derived component units, the content of component units derived from 1,6-hexanediamine was 100 mol %. Furthermore, the intrinsic viscosity [η] of polyamide resin (PA-3) was 0.65 dl/g, no melting point (Tm) was observed, the glass transition temperature (Tg) was 125°C, and the heat of fusion (ΔH) was 0 J/g.

The compositions and physical properties of polyamide resins (PA-1) to (PA-3) are shown in Table 1.

The intrinsic viscosity [η], melting point (Tm), glass transition temperature (Tg), and heat of fusion (ΔH) of polyamide resin were measured using the following methods.

[Intrinsic viscosity [η]]
In accordance with JIS K6810-1977, 0.5 g of polyamide resin was dissolved in 50 ml of 96.5% sulfuric acid solution to prepare a sample solution. The flow time of the obtained sample solution was measured using an Ubbelohde viscometer at 25±0.05°C. The measurement results were applied to the following equation to calculate the intrinsic viscosity [η] of the polyamide resin.
[η]=ηSP/[C(1+0.205ηSP)]
ηSP=(t-t0)/t0
[η]: Intrinsic viscosity (dl/g)
ηSP: specific viscosity C: sample concentration (g/dl)
t: number of seconds for the sample solution to flow down (seconds)
t0: Number of seconds (seconds) after blank sulfuric acid is flowed

[Melting point (Tm), glass transition temperature (Tg), heat of fusion (ΔH)]
The melting point (Tm), glass transition temperature (Tg), and heat of fusion (ΔH) of the polyamide resin were measured using a differential scanning calorimeter (DSC220C, manufactured by Seiko Instruments Inc.). Specifically, approximately 5 mg of polyamide resin was sealed in a measurement aluminum pan and set in the differential scanning calorimeter. The polyamide resin was then heated from room temperature to 350°C at 10°C/min. To completely melt the resin, the pan was held at 360°C for 3 minutes and then cooled to 30°C at 10°C/min. After leaving the pan at 30°C for 5 minutes, the pan was heated a second time to 360°C at 10°C/min. The temperature (°C) of the endothermic peak during this second heating was taken as the melting point (Tm) of the polyamide resin, and the inflection point corresponding to the glass transition was taken as the glass transition temperature (Tg). The heat of fusion ΔH was determined in accordance with JIS K7122 from the area of the exothermic peak of crystallization during the first temperature rise.

(2) Talc Talc: average particle size 6 μm

(3) Fibrous inorganic filler Glass fiber: ECS03T-251H manufactured by Nippon Electric Glass Co., Ltd. (glass fiber having an average fiber diameter of 10.5 μm)

(4) Lubricant: calcium montanate

3. Preparation and Evaluation of Metal/Resin Composite Structures [Examples 1 to 5 and Comparative Examples 1 to 7]
(Preparation of Pellets of Polyamide Resin Composition)
The polyamide resin, talc (B), glass fiber (D), and lubricant (E) shown in Table 2 were kneaded in the proportions shown in Table 2 using a 30 mmφ vented twin-screw extruder with a barrel temperature set at 335°C, and the mixture was pelletized using a pelletizer to obtain pellets of the composition.

(injection molding)
Next, a small dumbbell metal insert mold was attached to an injection molding machine J55AD manufactured by Japan Steel Works, Ltd. Next, the mold was heated to 160°C, and then a surface-treated metal member shown in Table 2 was placed in the mold.

The pellets of the polyamide resin composition prepared above were then dried for 24 hours at 110°C and 10 Torr (1330 Pa), after which they were placed in the hopper of the injection unit of the injection molding machine and injection molded at a cylinder temperature of 335°C, a mold temperature of 150°C, an injection speed of 40 mm/sec, a holding pressure of 90 MPa, and an injection holding pressure time of 8 seconds to obtain a metal/resin composite structure.

The bonding strength and fluidity of the resulting metal/resin bonded bodies were evaluated using the following methods.

(Joining strength)
A tensile tester Model 1323 (manufactured by Aiko Engineering Co., Ltd.) was used, and a dedicated jig was attached to the tensile tester. The breaking load (N) of the metal/resin composite structure was measured at room temperature (23°C) under the conditions of a chuck distance of 60 mm and a tensile speed of 10 mm/min.
The breaking load (N) was then divided by the area of the metal/resin joint to calculate the joint strength (tensile shear strength) (MPa).

(Flow length test (injection flowability))
Using a bar flow mold having a width of 10 mm and a thickness of 0.5 mm, injection was carried out under the following conditions, and the flow length (mm) of the resin in the mold was measured.
Injection molding machine: Sodick Plastec Co., Ltd., Tupearl TR40S3A
Injection pressure setting value: 2000 kg/ ^cm2
Cylinder set temperature: 335℃
Mold temperature: 150°C

The evaluation results for Examples 1 to 5 and Comparative Examples 1 to 7 are shown in Table 2.

As shown in Table 2, the metal/resin composite structures of Examples 1 to 5, which contain polyamide resin (A) and a specified amount of talc (B), exhibit high bonding strength. Furthermore, the polyamide resin compositions of Examples 1 to 5 also exhibit good fluidity during injection molding.

In particular, it can be seen that the addition of polyamide resin (C) further increases the bonding strength of the metal/resin composite structure (comparison between Examples 1 and 3).

In contrast, the metal/resin composite structures of Comparative Examples 1, 2, and 6, which do not contain polyamide resin (A), and the metal/resin composite structures of Comparative Examples 3 and 4, which do not contain talc, all exhibit low bonding strength.

The present invention provides a metal/resin composite structure in which a resin member made of a polyamide resin composition is firmly bonded and fixed to a metal member, a method for manufacturing the same, and an engine mount member.

100 Metal/resin composite structure 110 Metal member 111 Surface (joining surface)
120 Resin member

Claims (13)

A polyamide resin composition for metal-resin bonding, which is bonded to a surface having an uneven structure of a metal member having an uneven structure on the surface,
the concave-convex structure has a plurality of convex portions, and the center-to-center distance of the plurality of convex portions is 5 nm to 500 μm;
The polyamide resin composition for metal-resin bonding comprises:
A composition comprising a polyamide resin (A), talc (B), and a polyamide resin (C) ,
The polyamide resin (A) contains a component unit (a1) derived from a dicarboxylic acid and a component unit (a2) derived from a diamine ,
The dicarboxylic acid-derived component unit (a1) includes a terephthalic acid-derived component unit,
The diamine-derived component unit (a2) comprises a component unit derived from a linear aliphatic diamine having 4 to 15 carbon atoms, a component unit derived from a branched aliphatic diamine having 4 to 18 carbon atoms , and
Including,
the content of the talc (B) is 0.1 to 5% by mass relative to the polyamide resin composition,
The heat of fusion (ΔH) of the polyamide resin (C) measured by a differential scanning calorimeter is lower than that of the polyamide resin (A).
Polyamide resin composition for metal-resin bonding . the branched aliphatic diamine-derived component units include at least one of 2-methyl-1,8-octanediamine-derived component units and 2-methyl-1,5-pentanediamine-derived component units;
The polyamide resin composition for metal-resin bonding according to claim 1 . the component units derived from the linear aliphatic diamine include component units derived from 1,6-hexanediamine,
The branched aliphatic diamine-derived component units include 2-methyl-1,5-pentanediamine-derived component units .
The polyamide resin composition for metal-resin bonding according to claim 1 or 2 . The heat of fusion (ΔH) of the polyamide resin (C) is 0 to 5 J/g.
The polyamide resin composition for metal-resin bonding according to any one of claims 1 to 3 . The polyamide resin (C) contains a component unit (c1) derived from a dicarboxylic acid and a component unit (c2) derived from a diamine,
The dicarboxylic acid-derived component unit (c1) includes an isophthalic acid-derived component unit,
The diamine-derived component unit (c2) includes a component unit derived from an aliphatic diamine having 4 to 15 carbon atoms.
The polyamide resin composition for metal-resin bonding according to any one of claims 1 to 4 . The dicarboxylic acid-derived component unit (c1) may further include a terephthalic acid-derived component unit,
the molar ratio of the component units derived from isophthalic acid to the component units derived from terephthalic acid is such that the component units derived from isophthalic acid/the component units derived from terephthalic acid is 60/40 to 100/0;
The polyamide resin composition for metal-resin bonding according to claim 5 . The content of the polyamide resin (C) is 1 to 40 mass% based on the total amount of the polyamide resin (C) and the polyamide resin (A).
The polyamide resin composition for metal-resin bonding according to any one of claims 1 to 6 . The polyamide resin composition further contains a fibrous inorganic filler.
The polyamide resin composition for metal-resin bonding according to any one of claims 1 to 7 . The content of the fibrous inorganic filler is more than 0% by mass and 75% by mass or less with respect to the polyamide resin composition.
The polyamide resin composition for metal-resin bonding according to claim 8 . The metal member includes one or more selected from iron, high-tensile steel, stainless steel, aluminum, aluminum alloy, magnesium, magnesium alloy, copper, copper alloy, titanium, and titanium alloy;
The polyamide resin composition for metal-resin bonding according to any one of claims 1 to 9 . The content of the talc (B) is 0.1 to 0.35% by mass relative to the polyamide resin composition for metal-resin bonding.
The polyamide resin composition for metal-resin bonding according to any one of claims 1 to 10 . The average particle size of the talc (B) is 1 to 15 μm.
The polyamide resin composition for metal-resin bonding according to any one of claims 1 to 11 . The average particle size of the talc (B) is 6 to 15 μm.
The polyamide resin composition for metal-resin bonding according to any one of claims 1 to 11 .