JP2003103563A - Composite of metal and resin and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make merit of a metallic case body compatible with that of a synthetic resin structure and to attain high productivity, good mass-producibility and the freedom of the design of a shape and a structure, in regard to electronic equipment and the like. SOLUTION: A metal frame 6 pretreated is inserted into an injection mold for injecting a rib 7. A thermoplastic resin composition is filled on the surface of the metal frame by injection molding and thereby the rib 7 is molded. The metal frame 6 and the rib 7 made of the thermoplastic resin composition are joined integrally in the case body of a case cover 3 thus molded, and it is possible to make the most of the characteristic features of a metal in respect to both the strength and the design of outward appearance and moreover to attain intricacy of the shape and the structure inside the case body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-resin composite used for a housing of electronic equipment including an IC or the like, a structural component, and a method for manufacturing the same. More specifically, regarding the structure of a structure in which a metal and a thermoplastic resin made by sheet metal working, press working, cutting work, etc. are integrated, various industrial control devices, household electrical appliances, communication devices such as mobile phones, etc. , Medical equipment, housings for vehicles and building materials, structural parts,
The present invention relates to a composite of metal and resin used for exterior parts and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art A technique for integrating metal and synthetic resin is required from a wide range of fields such as manufacturing parts for automobiles, home electric appliances, industrial equipment, etc., and many adhesives have been developed for this purpose. . Among these are very good adhesives. An adhesive that exhibits a function at room temperature or by heating is used for joining a metal and a synthetic resin into one piece, and this method is a general technique at present.

However, there have been studies to find a more rational joining method that does not use an adhesive. Light metals such as magnesium, aluminum and their alloys,
As far as the present inventors know, a method of integrating a high-strength engineering resin with an iron alloy such as stainless steel without interposing an adhesive has not been put into practical use at present. The inventors of the present invention have made intensive research and development on these.

The reason why the present inventors proceed with this development is as follows. In other words, the recent development and market expansion of portable electronic devices such as mobile phones, portable personal computers, and PDAs require a structure that is lighter, stronger, and has an excellent appearance. It is made of a light alloy such as aluminum or magnesium, or a thin stainless sheet. The combination of the made exterior part and the chassis made of high strength resin whose material is completely different from this makes up that request,
There is a demand for rational joining methods between the two.

Further, in the IT era, since electromagnetic interference has entered the environment of not only businesses but also general consumers, it is necessary to shield electromagnetic waves emitted by electric and electronic devices as much as possible. Aluminum alloy as a shield material is a preferable shield material because it has a high malleability and is easy to work because it is a metal. On the other hand, the polybutylene terephthalate (PBT) resin mainly used in the present invention is excellent in heat resistance and mechanical strength, so if a method for joining the two is found by an easy means, it can contribute to this field. .

The use of the composite of metal and resin is not limited to the portable electronic equipment aiming at weight reduction and electromagnetic wave shielding as described above, but injection of metal and thermoplastic resin excellent in heat resistance and strength is also performed. If it can be firmly bonded by heat-pressing and other heat-molding processes, a surprisingly wide range of applications can be expected. That is, when it is used as a case or chassis in a stationary electronic / electric machine or a general machine (for example, a television, a personal computer, a sewing machine, etc.), there are great advantages in weight reduction and design. Also, if a lightweight and durable pipe is obtained from a composite of metal and resin, it may be used for the arms and legs of a robot (for example, a welfare robot). Furthermore, if practical technology is advanced to the point where the strength deterioration due to temperature cycling in a metal-resin composite can be completely suppressed, it can be used for a wide variety of mechanical parts. Furthermore, if the application is advanced until the composite of metal and resin can be used in mobile machines such as automobiles and airplanes, it will be the most promising application.

The insert molding method is first considered as the easiest joining means for the above purpose, considering cost and productivity. That is, bending and cutting a metal plate,
A thermoplastic resin melted after the metal shape is first made into a desired shape by a processing method such as pressing such as drawing and cutting such as milling, and then the metal shape is inserted into an injection mold. It is a method of injecting a composition.

An invention likely to be adapted to this means is disclosed and proposed in Japanese Patent Publication No. 5-51671. The proposed invention is similar to electroplating in which a metal plate of copper, brass, iron, stainless steel, nickel, zinc, aluminum or the like is immersed in an aqueous solution in which an alkali salt of triazine thiols, an amine ammonium salt or the like is dissolved. The idea is to perform an electrochemical treatment (in this invention, "organic plating").
Is called).

It has been shown that when this "organic plating" treatment is carried out, an organic material layer is firmly deposited on the metal surface and the surface becomes an organic layer. It is disclosed that if plastic sheets are stacked and pressed with a hot plate, metal and plastic stock are firmly bonded.

In order to re-try this proposed invention, the present inventors have tried using an aluminum alloy as a metal to be used and injecting various synthetic resins. In a follow-up experiment conducted by the present inventors, a high aluminum / resin adhesion (heat fusion) strength was confirmed when nylon 12 was used for this synthetic resin. Therefore, a detailed study was made on mass production, that is, commercialization by insert injection molding in which a molded aluminum metal was inserted and nylon 12 resin was injected into this mold.

However, the result of the examination was not so preferable. As a problem, for example, a pretreatment is required before the above-mentioned "organic plating" for removing oil and fat on the aluminum surface, for removing metal oxide, or for activation. This pretreatment should be carried out under a stable environment and under strict conditions, and the desired adhesive strength cannot be obtained. The conditions for applying "organic plating" are delicate and management during mass production is not easy. In that case, a good adhesive force cannot be obtained unless the mold temperature is considerably high. If the mold temperature is raised, the molding cycle becomes longer, and depending on the shape, the molded product may be deformed when released from the mold. It turns out that there are various problems such as that.

[0012]

[Problems to be Solved by the Invention] The above-mentioned proposed technology has not been commercialized by other companies in the same industry, and the present inventors have postponed commercialization. However, if a practical method can be established, it can be widely applied to various fields and the market is expected to be large. As the bonding method, we selected a bonding method by injection of engineering resin with a metal piece insert, a so-called injection molding method, and focused on reforming the surface layer on the metal side.

The present invention has been made based on the above technical background, and achieves the following objects. An object of the present invention is to strongly bond a metal and a resin, and to provide a metal-resin composite used for a housing of an electronic device and a method for producing the same. Another object of the present invention is to provide a composite in which a metal and a resin, which are used for a housing of an electronic device and the like, are strongly adhered by an injection molding method with high productivity, and a manufacturing method thereof. Still another object of the present invention is to use a metal having a high electromagnetic shielding property, and further, having a moldability of a synthetic resin, which is used for a casing of an electronic device, in which a metal and a resin are strongly adhered, and the production thereof. To provide a method.

[0014]

The present invention adopts the following means in order to achieve the above object. The metal-resin composite of the present invention is a metal form whose surface is treated with a water-soluble reducing agent, and on the surface, polyalkylene terephthalate, a copolymer mainly composed of the polyalkylene terephthalate,
Alternatively, the thermoplastic resin composition containing the polyalkylene terephthalate as a component is integrally attached. Here, it is preferable that the metal shape is subjected to a cutting and / or polishing step before the surface is treated with the water-soluble reducing agent.

[Metal Shaped Object] As the metal material of the metal shaped object, an aluminum alloy can be preferably used. Aluminum alloys are preferable because they have a large coefficient of thermal expansion and are excellent in malleability and workability. Metal shapes can be cut, cut, bent, drawn, polished, etc. by sawing, milling, drilling, pressing, grinding, polishing, etc. to obtain the shape and structure required for inserts in injection molding. To be done.
The metal shape processed into the required shape and structure requires that the surface to be bonded be thick and not be oxidized or hydroxylated, and those that show rust on the surface after being left for a long time are polished. Then need to be removed.

It should be noted that there is a metal shaped object to be noted. As will be described later in detail, since the metal material and the thermoplastic resin composition which is a synthetic resin material have different coefficients of thermal expansion, the length of expansion and contraction when heated or cooled is different. Since it is impossible to make the thermal expansion coefficients of both substantially the same, an integrated product,
That is, on the adhesive surface of the composite, a shift stress is always generated due to a temperature change. In the case of bonding with an adhesive, the difference in thermal expansion and contraction between the two uses an elastic adhesive, and the thermal strain is absorbed only by the deformation within this elastic deformation, but in the present invention, highly rigid ones are directly bonded. There is no escape. Therefore, it is necessary to devise a means for absorbing and relieving the displacement stress when the temperature changes.

One is that the aluminum alloy has the largest coefficient of thermal expansion among metals, and is therefore close to that of a resin material, which is preferable for the present invention. Further, even when an aluminum-based material is used, the thickness of the adhesive portion is It is better to reduce the displacement stress by making it as small as possible, and it is better that the surface to be the adhesive surface has a high surface roughness, so if the rough surface is formed in advance with a grindstone, sandpaper, etc. It is effective for adhesion of the composition and metal. In addition, it does not create long, straight adhesive surfaces. Alternatively, a method may be used in which convex bosses are formed on the surface of the metal and the joining force is mechanically used together.

[Cutting and / or polishing] The cutting and / or polishing referred to in the present invention means that after the necessary shaping is carried out by the above various metal working methods, further cutting and / or polishing is carried out. If the final step of forming the required shape is cutting or polishing, and if preservation from the end of the cutting or polishing is preferable as described later, cutting and / or polishing in this section can be omitted. . The purpose of this step is to renew the metal surface before contact with the water-soluble reducing agent so that the effect of the next step will be as uniform as possible over the renewed surface. This is because the metal surface is usually covered with oxides or hydroxides, but when stored for a long period of time, the oxide layer penetrates into the interior and becomes thick, and if it becomes severe, it becomes a rust surface.

To give an example of aluminum alloys, commercially available aluminum sheets have been baptized by pressure and heat in the rolling process, and there are also those whose surface is lightly acid-treated in order to improve weather resistance. The surface oxide layer is quite thick.
It is assumed that the aluminum plate is polished with a strong flow of compressed air mixed with fine sand grains (blast treatment). By this polishing, the surface covered with the oxide is peeled off, the metal aluminum atoms are exposed for a moment, and at the next moment, it is oxidized by oxygen in the air to form an oxide film. The thickness is thin. The metal shape after polishing does not change so quickly if it is stored under dry air, but under high temperature and high humidity, oxides and hydroxides increase and the original state (surface state before polishing) quickly approaches. . Therefore, for storage after this step, it is important to check the environment such as humidity temperature and shorten the period.

This step will be specifically described. Cutting is literally cutting. Polishing is preferably carried out using sandpaper, a powder abrasive, an abrasive paste, or the like. Polishing called sand blasting, air blasting, or blasting using sand grains or fine powder abrasives and compressed air or compressed nitrogen is more preferable. For the purpose, it is better that the temperature does not rise so much during polishing and the coexistence of moisture and water is small. Therefore, the blast treatment is preferable at the time of commercialization on the premise of mass production. The preservation of the metal shape after this step is as described above. According to the inventors of the present invention, the shape of the blast-treated aluminum alloy seemed to be almost the same as the one subjected to the next step immediately if it was stored in dry air for about one week.

[Washing] Since the surface of the metal-shaped object has processing oil and finger oil, it is washed. In addition, the metal shape after blasting is usually finished with a clean-up in which sand particles are blown off by a compressed air pulse, so a cleaning process may not be necessary, but since it has fine oil droplets and dirt,
Cleaning is not a bad thing. This washing is preferably performed by a combination of washing with an organic solvent and washing with water. For example, it is immersed in a water-soluble organic solvent such as acetone or ethanol to remove oily stains, washed with water, and air-dried with forced air. If strong oily substances are attached, wash with an organic solvent such as benzine or xylene, and then wash with water.
Air dry with forced air.

The storage period after washing should be as short as possible. If possible, the washing step and the next step (reducing agent treatment step)
Is preferably carried out subsequently. When the treatment is continuously performed in this way, the drying can be simplified and can be omitted in some cases. When storage is required until the next step, storage is preferably performed at least under dry air, and the temperature is preferably room temperature or lower. In the case of aluminum alloy shaped products,
Although it was the summer season, after washing and drying, it was stored in dry air at room temperature for 24 hours and sent to the next step. However, no significant difference was observed immediately from the thing sent to the next step. Although the present inventors have not performed it, it is theoretically possible that the effective period can be extended by storing it under dry nitrogen and at a low temperature.

[Treatment with a water-soluble reducing agent] Next, a specific method of treatment with a water-soluble reducing agent will be described. As the water-soluble reducing agent used in the present invention, hydrazine and its derivatives, alkali metal borohydrides, and alkali metal aluminum hydrides can be used. Preferably, hydrazine, sodium borohydride and lithium aluminum hydride can be used. These water-soluble reducing agents are dissolved in water so as to have a concentration of several%, and the above-mentioned cleaned metal shape is immersed therein for a certain period of time.

For example, the method for preparing the hydrazine treatment solution is as follows. Commercially available hydrazine hydrate or an aqueous hydrazine solution can be used as a raw material for the treatment liquid. Obtain this and dilute it with water to make the hydrazine concentration 1-5%, preferably 2-4%. Although depending on the aluminum alloy used, when an aluminum alloy of A1050 standard (Japanese Industrial Standard (JIS)) was used, good results were obtained when the hydrazine concentration of the hydrazine aqueous solution was set to 3% and immersed for 60 to 120 seconds.

When the concentration of the reducing agent is increased, it seems that the treatment time can be shortened, but the decomposition reaction of the reducing agent may proceed due to contact with a metal, which causes a danger in the process. From the viewpoint of safe work, too high a concentration is not preferable. On the other hand, when the concentration is lowered, the immersion time for exhibiting the effect becomes longer.

The treated metal form is preferably stored under dry air and protected from moisture. Confirmation experiments have not been carried out until it should be stored under dry nitrogen. In the case of the aluminum alloy, it was confirmed that the effect was retained even if the aluminum alloy was stored for up to 1 week at room temperature under dry air.

[Thermoplastic Resin Composition] Next, the thermoplastic resin composition used will be described. This thermoplastic resin composition is one or more selected from polyalkylene terephthalate, a copolymer mainly composed of polyalkylene terephthalate, or a thermoplastic resin composition containing polyalkylene terephthalate as a component. PBT is preferred as the polyalkylene terephthalate. Further, as the thermoplastic resin composition, a polymer of PBT alone,
Polymer compound of PBT and polycarbonate (PC), polymer compound of PBT and acrylonitrile butadiene styrene resin (ABS resin), PBT
And a polymer compound of polyethylene terephthalate (PET) are preferred.

Further, the inclusion of the filler is very important from the viewpoint of matching the thermal expansion coefficients of the metallic shape and the thermoplastic resin composition as described above. As the filler, glass fibers, carbon fibers, aramid fibers, and other high-strength fibers similar thereto are preferable. Further, a thermoplastic resin composition containing a pulverized product of calcium carbonate, magnesium carbonate, silica, talc, clay, carbon fiber or aramid fiber, and other similar resin-filling inorganic fillers is very preferable. Even if it does not contain a filler, it will adhere strongly and very strong force is required to peel off the thermoplastic resin composition adhered to the metal. However, when the molded composite is subjected to a temperature cycle test, in a resin system containing no filler, the adhesive strength may be rapidly reduced by repeated cycles. It is estimated that there are two causes for this.

One reason is that there is a large difference in linear expansion coefficient between the metal shape and the thermoplastic resin composition. Although the linear expansion coefficient of aluminum is the largest among metals, it is still considerably smaller than that of thermoplastic resins. The presence of the filler lowers the coefficient of linear expansion of the thermoplastic resin composition and brings it closer to the coefficient of thermal expansion of an aluminum alloy (2.386 × 10 ^{−5 for} pure aluminum). It is estimated that the linear expansion coefficient can be made quite close to that of aluminum alloy by selecting the kind of filler and its content.

The other is the relationship between the cooling shrinkage of the metal shape after insert molding and the molding shrinkage of the thermoplastic resin composition. The molding shrinkage of the thermoplastic resin composition containing no filler is about 0.6% even if it is small. On the other hand, the cooling shrinkage of the aluminum alloy is, for example, about 0.2% as it cools from injection to room temperature by about 100 ° C., which is much smaller than the molding shrinkage of the thermoplastic resin composition, and there is a difference between the two. Therefore, when the composite is released from the mold and time elapses, and the resin settles down, internal strain occurs at the interface between the metal and the resin, and the interface is destroyed by a slight impact and peeled off.

It has already been stated that the coefficient of thermal expansion of aluminum is the largest among the metals and is preferable as the metal species used. Nevertheless, the coefficient of thermal expansion of aluminum-based metals, more specifically, the coefficient of linear expansion with respect to temperature changes, is 2 to 3 × 10 ^-5 ° C ^-1 . On the other hand, the linear expansion coefficient of PBT or a polymer compound containing PBT is 7 to 8 × 10 ^-5 ° C ^-1 . In order to reduce the linear expansion coefficient of the PBT or the polymer compound containing PBT, the content of the filler is preferably high, and the content is preferably 20% or more, more preferably 30% or more.

High-strength fiber or inorganic filler in PBT or PBT-containing polymer compound in an amount of 30 to 50%
When included, the coefficient of linear expansion becomes 2-3 × 10 ^-5 ° C ^-1 , which is almost the same as that of aluminum. In addition, at this time, the molding shrinkage also decreases. In terms of molding shrinkage, the high crystallinity of PBT raises the shrinkage, so it is possible to further lower the compounding rate by mixing PET, PC, ABS, PS, etc., which are low crystalline resins, into a compound. However, since the PBT concentration also decreases, it is not clear yet.

[Injection molding] In the present invention, a metallic shape is immersed in an aqueous solution in which a water-soluble reducing agent is dissolved, dried, and then inserted into an injection molding die to form a die. After closing, the thermoplastic resin composition is injected into the cavity formed between the metal shape and the injection mold.

The injection conditions will be described. The higher the mold temperature and the injection temperature are, the better results are obtained. However, it is not forcibly raised, and a sufficient adhesive effect can be exhibited under almost the same conditions as in the ordinary injection molding using the thermoplastic resin composition. .
In order to increase the adhesive strength, it should be noted that pin gates are used as much as possible in the mold gate structure. It is thought that the pin gate will instantly raise the resin temperature due to the shearing friction that occurs when passing through the resin, and this will produce a good effect. In short, it is presumed that it is better to devise such that the high temperature resin melt comes into contact with the adhesive surface as much as possible within the range that does not hinder smooth molding.

[Operation] According to the present invention, the shape mainly containing metal, especially aluminum, and the thermoplastic resin composition containing polyalkylene terephthalate can be firmly adhered by the insert molding method. Practically, as the thermoplastic resin composition, PBT containing a high concentration of filler or a compound containing PBT as a main component is preferable. The reason why this is possible is that the metal is treated with a water-soluble reducing agent. By this reducing agent treatment,
It is presumed that a metal surface state having appropriate etching and appropriate reactivity was obtained. The use of the present invention is believed to be useful for reducing the weight of portable electronic devices and simplifying the manufacturing process of devices that require electromagnetic wave shielding.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. An example in which the housing of the electronic device of the present invention is adopted in a mobile phone will be described. FIG. 1 is a front view of a mobile phone equipped with the housing of the present invention. Mobile phone 1
The telephone main body 2 is made of resin, and an electronic device such as an IC that realizes the function of the telephone is installed inside the telephone main body 2.

The telephone main body 2 is composed of two bodies, and is divided into two parts by the dividing surface at the center in the thickness direction. A case cover 3 is arranged on the upper surface of the telephone main body 2, and a rear surface main body 4 is arranged on the rear surface thereof. The case cover 3 performs both the function of the control panel and the function of the telephone body 2, and a plurality of push buttons 5 are arranged to form a key group. The push button 5 drives contacts (not shown) arranged in the telephone body 2. The case cover 3 and the back surface main body 4 are integrally fixed by a fixing means (not shown) such as a screw or a notch.

FIG. 2 is a sectional view of the case cover taken along the line II-II in FIG. The outer surface of the case cover 3 is formed of a metal frame 6 made of an aluminum alloy. The metal frame 6 is made by plastic working by a press machine and a die driven by the press machine, and further machined as necessary. The plastic working method and machining method for this metal are well known and will not be described in detail here. The metal frame 6 shields electromagnetic waves generated from electronic components such as ICs or electromagnetic waves from other electronic devices.

The metal frame 6 is treated with a reducing agent such as hydrazine. On the inner surface of the metal frame 6,
The rib 7 made of a thermoplastic resin composition is integrally fixed to the partition wall for reinforcement. This fixing is injection-molded by the method described later and integrated with the metal frame 6. As the thermoplastic resin composition, the one as described above is used. Before injection-molding the ribs 7, the surface of the metal frame 6 is treated with a reducing agent such as hydrazine as follows.

A brief description will be given of the case of using hydrazine. A commercially available hydrazine hydrate aqueous solution having a concentration of 80% was diluted with ion-exchanged water to prepare a hydrazine aqueous solution having a concentration of 5% as a hydrazine hydrate. Into this hydrazine aqueous solution, the metal frame 6 whose surface was washed with an organic solvent or the like, washed with water and dried was put and dipped, and the solution was stirred.
After immersion for about 1 minute, the product was taken out and washed with separately prepared ion-exchanged water.

The metal frame 6 whose surface is treated with hydrazine is inserted into an injection molding die for injecting the rib 7. FIG. 3 is a cross-sectional view of an injection molding die in which the surface of the metal frame 6 is filled with the thermoplastic resin composition by injection molding. The pretreated metal frame 6 is inserted and arranged in the cavity 11 of the movable side mold plate 10.

The fixed mold plate 15 is closed with the metal frame 6 inserted in the cavity 11. The cavity 11 is
A space formed by the metal frame 6, the movable mold plate 10, and the fixed mold plate 15 in a state where the movable mold plate 10 and the fixed mold plate 15 are closed. Runner 17 in this cavity 11,
The molten resin forming the rib 7 is supplied through the gate 16 to form the rib 7. In the case of the completed case cover 3, the metal frame 6 and the rib 7 made of the thermoplastic resin composition are integrally joined to each other, and the characteristics of the metal are utilized in terms of strength and appearance. Moreover, the shape and structure of the inside of the housing can be complicated. The backside body 4 that constitutes the telephone body 2 together with the case cover 3 is manufactured in the same manner.

[0043]

EXAMPLES Examples of the present invention will be described below in place of experimental examples.

[Experimental Example 1] A commercially available 1 mm thick aluminum plate for electrical work obtained by a rolling method was used as 20 mm x 50 mm.
Was cut into 16 rectangular pieces. The aluminum piece was taken out by immersing it in 2 liters of acetone for 10 minutes, immersed in 2 liters of ion-exchanged water, stirred, opened in a plastic colander, and further washed with 1 liter of ion-exchanged water.

On the other hand, a commercially available hydrazine hydrate aqueous solution having a concentration of 80% was diluted with ion-exchanged water to prepare 2 liters of a hydrazine aqueous solution having a concentration of 5% as hydrazine hydrate. The water-drained aluminum pieces were put into this and the liquid was occasionally stirred with a glass rod. This operation causes small foaming from the surface of the aluminum piece. The aluminum piece was taken out of the hydrazine aqueous solution, with the time point when the surface became slightly blackish as the end point. This period was about 1 minute of immersion, which was quickly taken out using SUS tweezers and put into a beaker containing 2 liters of ion-exchanged water prepared separately.

After stirring well, the mixture was poured into a plastic colander to drain water, and ion-exchanged water was further applied to wash the aluminum pieces. After that, it was forcibly dried using an air gun, and stored in a polyethylene bag with a zipper capable of sealing the opening. This aluminum piece is inserted into an injection molding die, and PBT / PC resin containing 20% glass fiber and 10% carbon fiber (PBT about 90% + PC about 10%, "Toughpet S" manufactured by Mitsubishi Rayon Co., Ltd.) is injected, An integrated composite was obtained as shown in FIG.

In FIG. 4, 21 is a metal piece. This is the same thickness as the aluminum piece obtained earlier, 1 mm, which is 20 mm x
It has a rectangular shape of 50 mm. The resin composition is injected into the two pin gates 22 and 23 to form a boss 24 and a rib 25. The boss 24 has a circular adhesive surface with a diameter of 8 mm, and the rib 25 has an adhesive surface with an adhesive surface of 8 mm.
It has a rectangular shape of mm × 25 mm. Both the boss and the rib have a height of 8 mm, and the boss has a hole with a diameter of 2 mm in the center so that the threaded measuring end for torque measurement can be screwed.

More specifically, about the insert of the aluminum piece, the aluminum piece after the reducing agent treatment is taken out from the plastic bag by opening the chuck of the poly bag 3 days after the start of storage.
It was inserted into the mold by picking it up with gloves so that oil and the like would not adhere to it. The mold temperature was 90 ° C, and the final part temperature of the heating cylinder and the nozzle temperature of the injection molding machine were 270 ° C.

After the molded product was left in the room for 2 days after molding,
The adhesion was tested. I tried to peel off the resin part by pressing the aluminum plate part on the desk and pushing the tip of the boss and the rib strongly in the horizontal direction with my thumb, but I could not peel it off even if I pressed it until my finger was almost scratched. This simple test was carried out on two molded products, but they were the same.

Next, with respect to the other two pieces, the resin portion of the rib was directly above from above with the pliers (so that the pliers were in the vertical direction).
I grabbed it and tried to peel the rib by tilting the pliers. However, the adhesive surface of both pieces did not peel off at all, and the rib broke from the middle. When the boss was similarly sandwiched with pliers and bent, both could be peeled off from the aluminum plate, but small resin debris remained on the aluminum surface to which the boss was adhered, causing material destruction. Was there.

With respect to the other two pieces, the threaded measuring end was inserted into the hole in the boss and the torque measuring device was rotated. I tried to measure the torque when the boss was peeled off, but in all of them, the hole on the resin side was scraped around around the torque of about 50 Ncm and it spun, and the boss did not peel off.

Take another two pieces and place them on a metal plate,
A temperature cycle test between 90 ° C and -20 ° C was performed.
The temperature was raised from room temperature at + 1 ° C / min to 90 ° C for 2 hours, then returned to room temperature (25 ° C during the experiment) at a rate of -1 ° C / min, allowed to stand for 2 hours, and then again at the same rate- Cooled to 20 ° C. This is a temperature cycle test in which the temperature is raised at -20 ° C for 2 hours, then raised at + 1 ° C / minute, returned to room temperature, left for 2 hours, and then raised again. After a total of 10 cycles, the test was performed using the same pliers and torque measuring device as described above. The result was the same as the test result without the temperature cycle test.

A high temperature and high humidity test was carried out on another two pieces. Specifically, it was left for 24 hours under the conditions of 90 ° C. and 60% humidity, returned to room temperature for 1 hour, and then tested using the same pliers and torque measuring instrument as described above. The result was the same as the result of the above test without the high temperature and high humidity test.

[Experimental Example 2] Aluminum pieces treated with a reducing agent in the same manner as in Example 1 were prepared and stored. However, the one stored for one week after the treatment with the reducing agent was used. Except for this, in the same manner as in Experimental Example 1, ten test composites shown in FIG. 4 were obtained. The ten obtained pieces were subjected to a destructive test using pliers and a torque measuring device in the same manner as in Experimental Example 1.
However, it was divided into groups of five, and a group that was subjected to the temperature cycle test and a group that was not subjected to the temperature cycle test. However, all results were similar to Example 1 and the adhesion was very strong.

[Experimental Example 3] The thermoplastic resin composition to be injected was PBT (“Toughpet G1030B” manufactured by Mitsubishi Rayon Co., Ltd.) containing no filler. Except for this, the test composite shown in FIG.
I got 0. The ten obtained pieces were subjected to a destructive test using pliers and a torque measuring device in the same manner as in Experimental Example 1. However, it was divided into groups of five, and a group that was subjected to the temperature cycle test and a group that was not subjected to the temperature cycle test. The set which was not subjected to the temperature cycle test was similar to the experimental example 1 and the adhesion was very strong, but the five sets of the set which were subjected to the temperature cycle test were peeled off only by strongly pressing both the pliers and the boss with fingers. The absence of filler seemed to weaken the temperature cycling test.

[Experimental Example 4] 10 g of commercially available sodium borohydride was dissolved in 1 liter of ion-exchanged water to prepare an aqueous solution having a concentration of about 1%. Except that this aqueous solution was used instead of the hydrazine aqueous solution, the aluminum pieces were treated with a reducing agent in exactly the same manner as in Experimental Example 1, and the PBT resin composition was injection molded. After the molded product was left in the room for 2 days after molding, the adhesive strength was tested. I tried to peel the resin part by pressing the aluminum plate part on the desk and pushing the tip of the boss and the rib horizontally with my thumb strongly, but I couldn't remove it even if I pressed it until the finger was scratched.

Experimental Example 5 10 g of commercially available lithium aluminum hydride was slowly dissolved little by little in 1 liter of ion-exchanged water. It was presumed that there was foaming and that it was partly decomposed only by dissolving in water, but 10 g was dissolved regardless. Except that this aqueous solution was used instead of the hydrazine aqueous solution, the aluminum pieces were treated with a reducing agent in exactly the same manner as in Experimental Example 1, and the PBT resin composition was injection molded. After the molded product was left in the room for 2 days after molding, the adhesive strength was tested. I tried to peel the resin part by pressing the aluminum plate part on the desk and pushing the tip of the boss and the rib strongly in the horizontal direction with my thumb, but I couldn't remove it even if I pressed it until my finger was almost scratched.

[Experimental Example 6] A commercially available 1 mm thick aluminum plate for electrical work obtained by the rolling method was used as 20 mm x 50 mm.
Was cut into 100 rectangular pieces. The aluminum piece was attached to a rubber sheet with double-sided tape and placed in a blasting device. Air blasting was performed by setting the air pulse time so that the unevenness was about 5 μm level. After taking it out from the blasting machine for 5 hours on average, soak it in 4 liters of acetone for 10 minutes to take it out, soak it in 4 liters of ion-exchanged water, stir it, and open it in a plastic colander.
Further, 2 liters of ion-exchanged water was added for washing.

Next, in the same manner as in Experimental Example 1, the aluminum pieces were immersed in a 5% aqueous hydrazine solution for 2 minutes for treatment with a reducing agent, quickly taken out using SUS tweezers, and separately prepared 4 liters of ion-exchanged water. I put it in a beaker containing. After stirring well, it was poured into a plastic colander to drain water, and ion-exchanged water was further applied to wash the aluminum pieces. After that, it was forcibly dried using an air gun and placed in a dryer filled with a calcium chloride desiccant and stored.

Three days after the start of storage, the aluminum piece was taken out of the dryer, picked up with gloves so as to prevent oil and the like from adhering, and inserted into an injection molding die to make a glass fiber 20.
%, PBT / PET resin containing 10% carbon fiber (PBT approx. 85% and PET approx. 15%, original resin made by Mitsubishi Rayon Co., Ltd.)
Was injected to obtain an integrated composite as shown in FIG.
The mold temperature was 90 ° C, and the final part temperature of the heating cylinder and the nozzle temperature of the injection molding machine were 290 ° C.

After the molded product was left in the room for 1 week after molding,
The adhesion was tested. I tried to peel off the resin part by pressing the aluminum plate part on the desk and pushing the tip of the boss and the rib strongly in the horizontal direction with my thumb, but I could not peel it off even if I pressed it until my finger was almost scratched. This simple test was carried out on five molded products, but they were the same.

Next, with respect to a total of 70 pieces including the above-mentioned 5 pieces, the resin portion of the rib was grasped from above (with the pliers in the vertical direction) with the pliers, and the pliers were tilted to remove the ribs. However, the adhesive surface of all 70 pieces did not peel off at all, and the rib was broken from the middle. When the boss part was similarly pinched with pliers and bent, 15 pieces could be peeled off from the aluminum plate, but small resin debris remained on the aluminum surface to which the boss was adhered, causing material destruction. Was there.
The remaining 55 pieces could not be peeled off and the boss broke in the middle.

With respect to another 10 pieces, the threaded measuring end was inserted into the hole in the boss and the torque measuring device was rotated. I tried to measure the torque when the boss peeled off, but in all of them, around the torque of about 200 Ncm, the hole on the resin side was scraped and it spun, and the boss did not peel off.

Another 10 pieces were taken and placed on a metal dish, and a temperature cycle test between 120 ° C. and −20 ° C. was carried out. Increase the temperature from room temperature by + 2 ° C / min to 120 ° C. 2
Hold for a period of time, and then at room temperature at a rate of -2 ° C / min (25 during experiment)
℃) and leave for 2 hours, then at the same speed -20
Cooled to ℃. Place at -20 ℃ for 2 hours, this time + 2 ℃
It is a temperature cycle test in which the temperature is raised at a temperature of / min, the temperature is returned to room temperature, the temperature is left for 2 hours, and then the temperature is raised again. After a total of 200 cycles, the test was conducted using the same pliers and torque measuring device as described above. The result was the same as the test result without the temperature cycle test.

A high temperature and high humidity test was carried out on another 10 pieces. Specifically, under the conditions of 90 ° C and 60% humidity, 24
After leaving it for one hour and returning it to room temperature for one hour, a test was performed using the same pliers and torque measuring device as described above. The result was the same as the result of the above test without the high temperature and high humidity test.

When viewed as a whole, surprisingly stable results were obtained as a fracture test for adhesives. It is thought that this is because the aluminum surface was renewed by the blasting treatment, and as a result, the reducing agent treatment worked on the entire renewed surface and brought out stable surface performance.

[0067]

As described above in detail, in the composite of the present invention and the method for producing the same, the thermoplastic resin composition and the metal shape which are integrated can be easily integrated without peeling. Therefore, it was possible to make a housing of an electronic device that has no problem in terms of shape and structure and mechanical strength. According to the present invention, it is useful for reducing the weight of a mobile electronic device or the like having a metal housing and for simplifying the manufacturing process of a device that requires an electromagnetic wave shield.

[Brief description of drawings]

FIG. 1 is a front view of a mobile phone equipped with a housing of the present invention.

FIG. 2 is a cross-sectional view of the case cover taken along the line II-II in FIG.

FIG. 3 is a cross-sectional view of an injection molding die in which a surface of a metal frame 6 is filled with a thermoplastic synthetic resin by injection molding.

FIG. 4 is a three-dimensional view of the experimentally produced composite.

[Explanation of symbols]

1 ... Mobile phone 2 ... Phone body 3… Case cover 5 ... push button 6, 12 ... Metal frame 7 ... rib 11 ... Cavity 10 ... movable side template 15 ... Fixed side template

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B29L 31:34 B29L 31:34 (72) Inventor Masao Takahashi 1-9, Nihonbashihonmachi, Chuo-ku, Tokyo Taisei Plus Co., Ltd. (72) Inventor Masao Shiraishi 1-9 Nihonbashihonmachi, Chuo-ku, Tokyo Taisei Plus Co., Ltd. F-term (reference) 4F206 AA25 AB11 AB16 AD03 AD27 AH42 JA07 JB12 4F211 AA13 AA20 AA24 AA28 AB16 AB17 AD03 AD08 AD33 AG03 TA08 TC02 TH02 TH21 TN82

Claims (9)

[Claims] 1. A metal form whose surface is treated with a water-soluble reducing agent, a polyalkylene terephthalate, a copolymer mainly comprising the polyalkylene terephthalate, or a heat containing the polyalkylene terephthalate as a component on the surface. A composite of a metal and a resin, wherein one or more kinds selected from a plastic resin composition are integrally attached. 2. The metal-resin composite according to claim 1, wherein the water-soluble reducing agent is hydrazine. 3. The metal-resin composite according to claim 1, wherein the water-soluble reducing agent is an alkali metal borohydride or an alkali metal aluminum hydride. 4. The composite of metal and resin according to claim 1, which is selected from claims 1 to 3, wherein the metal shape is made of an aluminum alloy. 5. The metal / resin composite according to claim 1, wherein the polyalkylene terephthalate is polybutylene terephthalate. 6. A composite of a metal and a resin according to claim 1, wherein the thermoplastic resin composition is a polymer of polybutylene terephthalate alone, or a polymer compound of polybutylene terephthalate and polycarbonate. , A polymer compound of polybutylene terephthalate and acrylonitrile butadiene styrene resin, a polymer compound of polybutylene terephthalate and polyethylene terephthalate, a polymer compound of polybutylene terephthalate and polystyrene, and a composite of metal and resin. 7. The composite of metal and resin according to claim 6, wherein the compound is high-strength fiber such as glass fiber, carbon fiber or aramid fiber, and / or calcium carbonate, magnesium carbonate, silica, A composite of a metal and a resin, characterized in that inorganic fillers for resin filling such as talc and clay are added. 8. A composite of a metal and a resin according to claim 1, which is selected from claims 1 to 7, wherein the metal shape is cut and / or cut before the surface is treated with the water-soluble reducing agent. Alternatively, a metal-resin composite characterized by being subjected to a polishing step. 9. The method for producing a composite of a metal and a resin according to claim 1, wherein the metal shape is subjected to a treatment of immersing it in an aqueous solution in which a water-soluble reducing agent is dissolved. A method for producing a composite of a metal and a resin, which comprises drying, inserting the mold into an injection mold, closing the mold, and injecting the thermoplastic resin composition containing the polyalkylene terephthalate.