JP2020040247A - Metal-resin composite - Google Patents

Abstract

To provide a metal-resin composite that is excellent in sealability of a joining face, has high bond strength, and can ensure high heat shock resistance at low cost.SOLUTION: A metal-resin composite 1 contains a metal body 2 having an outer surface 4 on which a nano-sized recess 5 is formed, and a resin body 3 that covers the outer surface 4 to enter the nano-sized recess 5 and contains a polyamide resin containing a fluorene compound, as a main resin content. The nano-sized recess 5 preferably has 5-500 nm of a diameter, and 5-500 nm of a depth.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a metal-resin composite of a metal body having a nano-sized recess and a resin body.

In recent years, composite parts in which a metal body and a resin body are integrated have been adopted in various industries. For example, in the automotive parts manufacturing industry, conventionally used metal parts are being replaced with the above-mentioned composite parts due to the need for weight reduction of parts.
As a method of manufacturing a composite component of this type, for example, Patent Literature 1 discloses a roughening process in which the surface of an aluminum component is roughened with an etchant, and a bonding process in which a resin composition is bonded to the roughened surface. Wherein the etching agent is an alkaline etching agent containing an amphoteric metal ion, an oxidizing agent and an alkali source, and an acid containing at least one of ferric ion and cupric ion and an acid. Disclosed is a method for producing an aluminum-resin composite, which is at least one selected from a series of etching agents.

JP 2013-52671 A Japanese Patent No. 5302315 Japanese Patent No. 5728025 JP-A-2006-128590 International Publication No. WO 2017/026250

The joint surface between the resin body and the metal body of the metal-resin composite is preferably a fine uneven surface from the viewpoint of ensuring excellent sealing properties at the joint surface.
Therefore, it has been studied to form fine irregularities on the outer surface of the metal body and join the resin body to the outer surface. However, if the irregularities are very small, such as nano-sized, it is difficult to flow the resin body into the irregularities, and the bonding strength between the resin body and the metal body tends to decrease. In particular, when a polyamide resin is used, the joining strength is significantly reduced.

On the other hand, since polyamide resins have high heat shock resistance and can be procured at relatively low cost, there is a demand to use them as resin materials for metal-resin composites.
An object of the present invention is to provide a metal-resin composite having excellent sealing properties at a joint surface between a resin body and a metal body, high bonding strength between the resin body and the metal body, and high heat shock resistance at low cost. To provide a metal-resin composite that can ensure the following.

The metal-resin composite (1) of the present invention includes a metal body (2) having an outer surface (4) on which a nano-sized recess (5) is formed, and a recess (5) of the metal body (2). And a resin body (3) that covers the outer surface (4) so as to penetrate and contains a polyamide resin containing a fluorene-based compound as a main resin component.
In the metal-resin composite (1) of the present invention, the nano-sized concave portion (5) may have a diameter of 5 nm to 500 nm and a depth of 5 nm to 500 nm.

In the metal-resin composite (1) of the present invention, the content of the fluorene-based compound in the resin body (3) may be 0.5 to 10% by mass.
In the method for producing a metal-resin composite (1) of the present invention, a step of forming a nano-sized recess (5) on an outer surface (4) of a metal body (2); 5) covering the outer surface (4) of the metal body (2) with a resin body (3) containing a polyamide resin containing a fluorene-based compound as a main resin component so as to penetrate the metal body (2).

In the method for producing a metal-resin composite (1) of the present invention, the step of forming the concave portion (5) may include a step of forming the concave portion (5) by etching.
In the above description, the numerals and the like in parentheses indicate the reference numerals of the corresponding components in the embodiment described later, but these reference numerals do not limit the scope of the claims.

As described above, according to the metal-resin composite of the present invention, since the resin body enters the recess, the metal body and the resin body can be anchor-joined. Since the concave portion has a nano size, the sealing property of the joint surface between the metal body and the resin body can be improved.
In addition, since the resin body contains a polyamide containing a fluorene-based compound as a main resin component, the viscosity of the resin body in a low shear rate region is reduced, and the resin body flows well into the nano-sized recess. be able to. As a result, the resin body can be firmly engaged with the concave portion of the metal body, so that a high bonding strength can be developed between the metal body and the resin body.

  Further, since the main resin component of the resin body is polyamide, the metal-resin composite has high heat shock resistance and can be manufactured at low cost.

FIG. 1 is a schematic sectional view of a metal-resin composite according to one embodiment of the present invention. FIG. 2 is a diagram showing a surface state of the metal body of FIG. FIG. 3 is a diagram for comparing a difference in bonding strength between PPS and PA66 with respect to a metal body. FIG. 4 is a diagram showing the relationship between the shear rate and the viscosity of each of PPS and PA66. FIG. 5A is a diagram for explaining the interaction between the molecular chains of PA66, and FIG. 5B is a diagram for explaining the interaction between the molecular chains of PPS. FIG. 6A is a diagram showing the state of the molecular chain of PA66 in the high shear rate range, and FIG. 6B is a view showing the state of the molecular chain of PA66 in the low shear rate range. FIG. 7 is a diagram showing the state of the molecular chain of PA66 containing a fluorene-based compound. FIG. 8 is a diagram showing the bonding strength between a resin body and a metal body in Examples, Comparative Examples, and Reference Examples.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic sectional view of a metal-resin composite 1 according to one embodiment of the present invention. FIG. 2 is a diagram showing a surface state of the metal body 2 of FIG.
The metal-resin composite 1 is used as a composite component in which a metal body and a resin body are integrated, and has a wide variety of industrial fields. Such industrial fields include, for example, transport machinery / equipment manufacturing, electronic component / device / electronic circuit manufacturing, production machinery / equipment manufacturing, electric machinery / equipment manufacturing, and the like. More specific applications include, for example, a housing for a torque sensor and a rack housing constituting an electric power steering (EPS) in an automobile and its accessories manufacturing industry, and an electric oil pump for idling stop (EOP). Various housing members such as a housing of the vehicle, for example, various gears such as a reduction gear for electric power steering, for example, a resin retainer of a bearing, a door roller of a sliding door car (resin wound bearing), a hydraulic or electro-hydraulic power steering And a reservoir tank for use. The industrial fields and applications of the metal-resin composite 1 listed above are merely examples, and the metal-resin composite of the present invention can be applied to a wide variety of industrial fields and applications.

The metal-resin composite 1 includes a metal body 2 and a resin body 3.
Examples of the metal material applicable to the metal body 2 include aluminum, copper, steel, magnesium, titanium, and the like. Note that the listed metal materials may be alloys of the materials.
The metal body 2 has an outer surface 4 that forms a bonding surface with the resin body 3.

As shown in FIG. 2, on the outer surface 4 of the metal body 2, a large number of nano-sized concave portions 5 are formed in a dot shape. Here, the nano-sized concave portion 5 means a concave portion having a diameter of more than 0 nm and less than 1000 nm.
In this embodiment, it is not necessary for the multiple recesses 5 to have the same diameter uniformly. For example, as shown in FIG. 2, the diameter _{D 1} of the one recess 5 is about 50 nm, the diameter _{D 2} of the other recess 5 may be about 20 nm. Preferably, the recess 5 has a diameter of 5 nm to 500 nm and a depth of 5 nm to 500 nm. The size (diameter, depth) of such a recess 5 can be measured, for example, from an image observed with an electron microscope.

Further, the large number of recesses 5 preferably occupy 15% to 85% of the surface area of the outer surface 4 of the metal body 2. For example, the occupancy of the recess 5 on the outer surface 4 of the metal body 2 can be measured from an image observed with an electron microscope.
The recess 5 of the outer surface 4 of the metal body 2 can be formed by roughening the outer surface 4 of the metal body 2 by, for example, chemical etching, laser etching or the like. As an example, the concave portion 5 can be formed by a surface treatment method described in paragraphs [0056] to [0090] of Patent Document 2 and paragraphs [0021] to [0029] of Patent Document 3 and the like.

  Polyamide (PA) is used as a resin material of the resin body 3. In addition to polyamide, for example, resins such as polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), polyacetal (POM), and thermoplastic elastomer (acid-modified ethylene-based elastomer, EGMA, EPDM, polyamide elastomer, etc.) are referred to as polyamide. You may use together. In this case, the amount of the resin other than the polyamide is preferably small from the viewpoint of cost without impairing the physical properties of the polyamide in the resin body 3. For example, in the resin portion of the resin body 3, the amount is 0 to 30% by mass. Preferably, there is. On the other hand, the amount of polyamide in the resin portion of the resin body 3 is preferably, for example, 70 to 100% by mass, and is 100% by mass (that is, use of polyamide alone in the resin portion excluding reinforcing fibers described below). Is more preferable.

  Examples of the polyamide used include, for example, aliphatic polyamides (PA6, PA66, PA46, PA410, PA12, PA612, PA610, PA11, etc.) and aromatic polyamides (PA6T, PA9T, PA10T, PA6T / X, PAMDX6, PPA). ) And the like. Of these, aliphatic polyamides are preferably used, and polyamide 66 (PA66) is more preferably used. These can be used alone or in combination of two or more.

  The resin body 3 covers the outer surface 4 of the metal body 2 so as to enter the recess 5 and is joined to the metal body 2. Specifically, the resin body 3 is directly bonded to the metal body 2 by the anchor effect of the portion 6 of the resin body 3 that has entered the recess 5. In addition to the expression that the resin body 3 is bonded to the metal body 2, the “resin body 3” is “fixed to the metal body 2”, “attached to the metal body 2”, “ May be expressed. "

  Here, the inventor of the present application examined how the bonding strength of each of polyphenylene sulfide (PPS) and polyamide (PA66) changes according to the size (diameter) of the concave portion 5 of the metal body 2. The resins used were polyphenylene sulfide (FZ-2140 (trade name) manufactured by DIC Corporation) and polyamide (70G33HS1L (trade name) good flow grade manufactured by Dupont).

As shown in FIG. 3, as shown in FIG. 3, when the size of the concave portion 5 was 1 μm or more, both the polyphenylene sulfide and the polyamide could be bonded to the metal body 2 with almost the same and relatively high strength.
On the other hand, if the size of the concave portion 5 is very small, such as 5 nm to 500 nm (nano size), the result is that the polyamide does not bond to the metal body 2. Although the polyamide used was a commercially available good-flow grade, there was a large difference in bonding strength as compared with polyphenylene sulfide.

Then, as a result of earnest study by the inventor of the present application, it has been found that there is a difference in viscosity in a low shear rate region between polyphenylene sulfide and polyamide. More specifically, as shown in FIG. 4, for example, in a high shear rate region where the shear rate exceeds 100 sec ⁻¹ , the viscosity of the polyamide is lower than the viscosity of polyphenylene sulfide, but as the shear rate decreases, The viscosity of polyphenylene sulfide is lower than that of polyamide. For example, the viscosity of polyphenylene sulfide is lower than the viscosity of polyamide in a low shear rate range of 1 sec ^-1 or less, and the viscosity difference is large in a speed range of 0.1 sec ^-1 or less. Therefore, it was thought that if the viscosity of the polyamide in the low shear rate region was reduced, the bonding strength to the metal body 2 having the nano-sized concave portions 5 could be improved.

Next, in order to reduce the viscosity of the polyamide in a low shear rate region, attention was paid to the difference in molecular structure between polyphenylene sulfide and polyamide.
More specifically, as shown in FIG. 5A, in the polyamide (PA66), molecular chains are cross-linked by a hydrogen bond between an oxygen atom (O) and a hydrogen atom (H). As shown in (1), in polyphenylene sulfide (PPS), such a hydrogen bond does not exist, and molecular chains are not cross-linked. That is, it is considered that the presence or absence of the hydrogen bond between the molecular chains affects the difference in the viscosity in the low shear rate region.

As shown in FIG. 6A, such a hydrogen bond is broken by a high shear force in a high shear rate region, and thus it is considered that the degree of freedom of each molecular chain is increased. This is demonstrated by the fact that the viscosity of the polyamide in a high shear rate region exceeding 100 sec ^-1 is lower than that of polyphenylene sulfide, as shown in FIG. In addition, polyphenylene sulfide has no hydrogen bond between molecular chains, but the large benzene ring acts as an obstacle and the degree of freedom is lower than that of polyamide, so the viscosity in the high shear rate region is higher than that of polyamide. it is conceivable that.

On the other hand, as shown in FIG. 6B, in the low shear rate region, the hydrogen bond is not broken by the low shear force, the movement of each molecular chain is limited by the hydrogen bond still existing, and the viscosity of the polyamide is lower than that of polyphenylene sulfide. It is expected to be higher.
Therefore, in this embodiment, the resin body 3 containing polyamide as a main resin component contains a fluorene-based compound. As a result, as shown in FIG. 7, the fluorene-based compound acts on the hydrogen bond, the bond strength of the hydrogen bond can be reduced, and even in a low shear rate region, compared with the case where the fluorene-based compound is not added. Therefore, it is considered that the degree of freedom of each molecular chain is increased.

Examples of the fluorene-based compound to be used include fluorene-based compounds described in paragraphs [0017] to [0032] of Patent Document 4 and fluorene-based compounds described in paragraphs [0064] to [0090] of Patent Document 5. No.
In the resin body 3, the content of the fluorene-based compound is, for example, 0.5 to 10% by mass, and preferably 2.5 to 7.5% by mass. When the content of the fluorene-based compound is 0.5 to 10% by mass, it is possible to ensure excellent bonding strength between the resin body and the metal body while favorably suppressing the deterioration of the base material properties of the resin body 3. Can be.

In addition, the resin body 3 may contain reinforcing fibers as necessary. The content of the reinforcing fibers may be, for example, 0 to 70% by mass. Examples of the reinforcing fiber include various fibers such as carbon fiber, glass fiber, and aramid fiber.
Further, the resin body 3 may contain an optional additive other than the fluorene-based compound, if necessary. Optional additives include, for example, fillers, colorants, conductive agents, flame retardants, flame retardant aids, plasticizers, lubricants, antioxidants, ultraviolet absorbers, heat stabilizers, release agents, antistatic agents , A dispersant, a flow regulator, a leveling agent, an antifoaming agent, a surface modifier, a low stress agent, a nucleating agent, a crystallization accelerator and the like. These can be used alone or in combination of two or more.

Next, a method for manufacturing the metal-resin composite 1 will be described.
To manufacture the metal-resin composite 1, for example, the concave portion 5 is formed in the metal body 2 by roughening the outer surface 4 of the metal body 2 by chemical etching, laser etching or the like.
On the other hand, a resin material containing polyamide as a main resin component is melted (melted and mixed if necessary), and the fluorene-based compound is added to the molten resin in the above-described mixing ratio. At that time, an optional additive may be added.

  Next, a mold having a retainer for holding the metal body 2 (metal core) is prepared. Then, with the metal body 2 held by the retainer, the mold is connected to the injection molding apparatus. In this state, the resin material containing the polyamide and the fluorene-based compound melted in the injection molding apparatus is injected into the cavity of the mold, and then cooled, whereby the metal body 2 and the resin body 3 are integrated. A molded product (metal-resin composite 1) is obtained.

As described above, according to the metal-resin composite 1, as shown in FIG. 1, since the resin body 3 enters the recess 5, the metal body 2 and the resin body 3 can be anchor-joined. Since the concave portion 5 has a nano size, the sealing property of the joint surface between the metal body 2 and the resin body 3 can be improved.
In addition, since the resin body 3 contains a polyamide containing a fluorene-based compound as a main resin component, the viscosity of the resin body 3 in a low shear rate region is reduced, and the resin body 3 ( Molten resin) can be satisfactorily flowed. As a result, the portion 6 of the resin body 3 can be firmly engaged with the concave portion 5 of the metal body 2, so that a high bonding strength between the metal body 2 and the resin body 3 can be exhibited.

  Further, since the main resin component of the resin body 3 is polyamide, the metal-resin composite 1 has high heat shock resistance and can be manufactured at low cost.

Next, the present invention will be described based on examples, comparative examples, and reference examples, but the present invention is not limited to the following examples.
<Example 1, Comparative Example 1, and Reference Examples 1-2>
(A) Preparation of Raw Material Resin The raw material resin shown in Table 1 below was melted in an injection molding apparatus, and additives were added at a predetermined mixing ratio. In addition, about the comparative example 1, the additive was not added.
(B) Roughening treatment of metal body NMT2 treatment of Taisei Plus Co., Ltd. was performed on a metal body made of an aluminum alloy (A7075) to form a large number of nano-sized recesses on the surface of the metal body. This recess generally had a diameter of 5 nm to 500 nm and a depth of 5 nm to 500 nm. Further, the concave portion was formed on almost the entire surface of the metal body.
(C) Molding of Insert Molded Product While the metal body 2 having the nano-sized concave portion was held by a mold retainer, the mold was connected to an injection molding apparatus. In this state, the raw resin melted in the injection molding apparatus is injected into the cavity of the mold, and then cooled to form a molded product (metal-resin composite) in which the metal body and the resin body are integrated. I got

<Evaluation test>
The joining strength between the metal body and the resin body of the insert molded product obtained in Example 1, Comparative Example 1, and Reference Examples 1 and 2 was measured. More specifically, it was manufactured in a state where samples of length × width × thickness = 75 mm × 10 mm × 4 mm were butt-joined to each other at a junction between the metal body and the resin body. Thereby, a test sample of length × width × thickness = 150 mm × 10 mm × 4 mm was obtained. By pulling this test sample toward the metal body side and the resin body side, it was measured how much force the joint was broken. The results are shown in FIG.

  As shown in FIG. 8, in Example 1 in which the fluorene-based compound was added, the bonding strength between the metal body and the resin body was improved about 1.5 times as compared with Comparative Example 1 in which no fluorene-based compound was added. It was found that the bonding strength of Example 1 was comparable to the bonding strength when using polyphenylene sulfide (PPS) shown in FIG. Comparing polyamide and polyphenylene sulfide, polyamide can be procured at a relatively low cost, so if the formulation of Example 1 is used, the cost of the metal-resin is low and the bonding strength between the metal body and the resin body is high. A complex can be obtained.

  On the other hand, in Reference Examples 1 and 2, the lubricant (external lubricant, internal lubricant) generally used to increase the fluidity of the resin material was blended, but the bonding strength between the metal body and the resin body was The result was far lower than that of Example 1 and lower than that of Comparative Example 1 in which no additive was added. That is, in order to allow the resin to flow into the nano-sized concave portions favorably, any additive may be used as long as it is an additive for increasing the fluidity. Has been demonstrated.

As mentioned above, although one Embodiment of this invention was described, this invention can be implemented in another form.
For example, various design changes can be made within the scope of the matters described in the claims.

  DESCRIPTION OF SYMBOLS 1 ... Metal-resin composite, 2 ... Metal body, 3 ... Resin body, 4 ... Outer surface, 5 ... Recess (of metal body), 6 ...

Claims (5)

A metal body having an outer surface on which nano-sized recesses are formed,
A metal-resin composite, comprising: a resin body that covers the outer surface so as to enter the concave portion of the metal body and includes a polyamide resin containing a fluorene-based compound as a main resin component.   The metal-resin composite according to claim 1, wherein the nano-sized recess has a diameter of 5 nm to 500 nm and a depth of 5 nm to 500 nm.   The metal-resin composite according to claim 1 or 2, wherein the content of the fluorene-based compound in the resin body is 0.5 to 10% by mass. Forming a nano-sized recess on the outer surface of the metal body,
Covering the outer surface of the metal body with a resin body containing a polyamide resin containing a fluorene-based compound as a main resin component so as to enter the concave portion of the metal body. The method of manufacturing a metal-resin composite according to claim 4, wherein the step of forming the recess includes the step of forming the recess by etching.

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