JP2000271957A - Production of metal insert resin molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively produce a metal insert resin molded product easy to produce and capable of ensuring airtightness sufficient to protect the electric part or electric contact in a part even in spite of a severe environmental change. SOLUTION: In a method for producing a resin molded product in which a metal part comprising copper or a copper alloy is inserted, a black oxide film is preformed on the surface of the metal part comprising copper or a copper alloy wholly or partially and this metal part is inserted in the mold of an injection molding machine to perform injection molding by using a thermoplastic resin material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a resin molded product in which a metal part made of copper or a copper alloy is inserted.

[0002]

2. Description of the Related Art Resin composite parts obtained by insert molding of metal parts are used in a wide variety of industrial fields, mainly in the fields of electrics and automobiles. There are various types of such resin composite molded parts, and the purpose of inserting a metal part also differs depending on the function and use of the product, but for example, it is used for various sensor parts such as a speed sensor used in automobiles and home electric appliances. Button type switch parts.
In the former example, generally, a metal terminal is inserted into a metal mold for injection molding together with a wound coil bobbin and the like, and is integrally molded with resin. At this time, since the metal terminal has a function of electrically connecting the inside and the outside of the molded product, a part of the metal terminal is molded so as to be exposed from the surface of the resin molded product. As is well known, automobile parts are used in a harsh environment, and in particular, electric and electronic parts are susceptible to moisture and moisture, so that it is necessary to prevent them from easily entering the inside. However, it is generally difficult to bond a metal and a resin. In particular, in metal insert molding using a thermoplastic resin, almost no adhesion between the metal and the resin is obtained, and moisture and water are not easily absorbed through the interface between the metal and the resin. Moisture easily enters the interior. For this reason, conventionally, countermeasures such as applying a thermosetting adhesive to the boundary portion between the metal terminal and the resin by post-processing, or assembling and sealing a rubber-like protected component have been taken. On the other hand, in the latter example, the hoop-shaped copper lead frame is fed into the injection mold and inserted.
It is continuously and integrally molded with resin. Next, bending, trimming, assembling, and the like of the externally exposed terminal portion are sequentially performed, and the completed switch component is finally soldered to a printed circuit board or the like, thereby constituting a part of a home appliance or the like. .
One of the problems in the process of manufacturing such a switch component is that flux enters the switch during the soldering process. In other words, the solder flux previously applied to the metal terminals as a solder adhesion improver reduces the viscosity due to the heat during soldering, and a part of the flux conveys the interface between the metal and the resin and contaminates the internal contacts of the switch. Poor electrical contact may occur. For this reason, conventionally, flux penetration has been prevented by applying a fluorine-based water repellent or the like to the base of the terminal in advance and then soldering.

[0003]

A problem common to the above-mentioned examples is that, in order to protect an electric circuit and an electric contact inside the part from external influences such as moisture and humidity, the parts are not easily assembled during the assembly process. Secondary processing and installation of protection parts are necessary,
This complicates the production process and increases the cost of the product. The root cause of this problem is that it is originally difficult to obtain a strong chemical interaction (such as a chemical bond) between a thermoplastic resin and a metal such as copper, and therefore, it is merely an injection molding die. Even if hot melted resin is poured into the inside and the insert metal is coated, it is practically possible to prevent the formation of extremely minute gaps at the resin / metal interface during the cooling process of the molded product and subsequent changes in the use environment. Was difficult. Therefore, an object of the present invention is to provide an inexpensive manufacturing method of a metal insert resin molded product that is easy to manufacture and that can secure sufficient airtightness to protect electric circuits and electrical contacts inside components even under severe environmental changes. It is to provide a method.

[0004]

Means for Solving the Problems As a result of intensive studies in view of such circumstances, the present inventor previously formed a black oxide film on all or a part of the surface of a metal component made of copper or a copper alloy, and then formed a black oxide film. By inserting metal parts into the mold of the injection molding machine and injection molding using a thermoplastic resin material, it is possible to ensure initial airtightness, as well as to be high even after severe environmental degradation tests such as cooling and heating cycle tests The present inventors have found that airtightness can be obtained and the product can be easily commercialized, and have led to the present invention. That is, the present invention is a method for producing a resin molded product in which a metal component made of copper or a copper alloy is inserted, and a black oxide film is formed on all or a part of the surface of the metal component made of copper or a copper alloy in advance. Forming a metal part, and then inserting the metal part into a mold of an injection molding machine and performing injection molding using a thermoplastic resin material.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a specific configuration of the present invention will be described in detail. First, a method of forming a black oxide film on the surface of a metal component made of copper or a copper alloy used in the present invention will be described. This method is generally called a blackening treatment, and is performed by immersing copper or a copper alloy in an aqueous solution of a hydroxide (eg, sodium hydroxide) and a chlorite (eg, sodium chlorite). , An ultrafine projection-like black oxide film is formed on the surface of copper or a copper alloy. This metal treatment method is mainly used in the manufacturing process of a glass-epoxy printed circuit board, and is performed for the purpose of improving the adhesion of the epoxy resin to the copper foil when bonding the epoxy resin to the copper foil. Have been done. On the other hand, as for the thermoplastic resin, as is well known, in the molding process, except for the behavior such as partial decomposition of the polymer due to heat, generally, it shows almost no chemical reactivity such as crosslinking, and in the cooling process. There are also effects such as shrinkage behavior,
Almost no remarkable adhesion improving effect as obtained by the combination of the blackened metal and the thermosetting resin was recognized, and it has not been used for metal insert molding of a thermoplastic resin. Nevertheless, as shown in the examples of the present invention described later, since a remarkable improvement effect was found with respect to airtightness, good airtightness when blackening-treated metal was insert-molded with a thermoplastic resin. It is thought that there is a mechanism other than adhesion at the resin / metal interface for the expression. Regarding this mechanism, according to the study of the present inventor, the fine coating structure generated on the metal surface by the blackening treatment results in an extremely large contact area with the resin,
As a result, it is presumed that the airtightness required for practical use is ensured because the passage for moisture and humidity to travel through the metal / resin interface and enter the interior of the component is significantly extended.

Next, the thermoplastic resin material used in the present invention will be described. The thermoplastic resin used in the present invention, polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene copolymer resin, polyvinyl chloride resin, polycarbonate resin, polyamide resin,
Polyacetal resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene sulfide resin, liquid crystalline polyester resin, polyimide resin, syndiotactic polystyrene resin, polycyclohexane dimethylene terephthalate resin and the like, and more preferably, molding processing Polyacetal resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene sulfide resin, polyamide resin, liquid crystalline polyester resin, polyimide resin, syndiotactic polystyrene resin, polycyclohexane dimethylene terephthalate, which is easy and has excellent electrical and mechanical properties Thermoplastic resin containing as a main component at least one resin selected from the group consisting of resins is preferably used. It is. As the thermoplastic resin material used in the present invention, in addition to the above thermoplastic resin, various known inorganic and organic fillers, flame retardants, flame retardant auxiliaries, ultraviolet absorbers, and stabilizers as long as airtightness is not deteriorated. Of course, it may contain additives such as colorants, processing aids and the like.

Next, an injection molding apparatus is generally used to insert-mold the blackened metal part using the thermoplastic resin material. The injection molding apparatus used in the present invention is not special, and a commercially available injection molding machine can be used. There is no particular limitation on the molding method and molding conditions in the present invention, but as common general knowledge in insert molding, it is desirable to adjust the conditions so that the molten resin comes into firm contact with the insert metal and a sufficient holding pressure is applied.

[0008]

EXAMPLES Examples of the present invention will be described below.
The present invention is not limited to these examples unless departing from the gist of the present invention. In the embodiment, the shape of the insert metal part (made of brass) used for resin molding is shown in FIG.
FIG. 2 shows the shape of a resin molded product obtained by inserting the metal component into an injection mold and performing injection molding with a thermoplastic resin. FIG. 3 is a schematic view of a test device in an airtightness evaluation performed using the resin molded product.
Shown in Further, in the examples, the method used for evaluating the airtightness is as follows.

(1) Airtightness test The resin molded product shown in FIG.
The airtightness was evaluated using the test device shown in FIG. First, a method of setting an evaluation sample is as follows. A resin molded product is set in a metal container portion of a pressure-resistant airtight container via a rubber O-ring, and then fixed so that the resin molded product is sandwiched between metal upper lids (container The male part and the female part are cut into the upper part and the upper lid part, respectively, so that they are fixed). The pressure-resistant airtight container was put into a water tank, and the pressure in the pressure-resistant airtight container was gradually increased by gradually opening the compressed air valve until a desired pressure was reached, and the presence or absence of air leakage from the metal insert was confirmed. If there is no air leakage in a still state for 1 minute under a predetermined pressure, the airtightness under the pressure is determined to be OK.
The test was started at 0.1 MPa, and if OK, the test was sequentially increased by 0.1 MPa, and the test was performed up to a maximum of 0.6 MPa. For samples that were OK at 0.6 MPa in the airtightness test in the initial state, the airtightness test was similarly performed after performing the following heat shock resistance test for a predetermined cycle. The test is n
= 5 samples. (2) Heat shock resistance test A commercially available heat shock tester was used.
hr to 180 ° C. × 2 hr) as one cycle, and the resin molded product was taken out of the tank every 20 cycles and subjected to the above airtightness test to evaluate heat shock resistance.

Example 1 A brass insert part shown in FIG. 1 was electrolytically degreased using a commercially available degreasing agent (Enbond CA / Meltex Co., Ltd.), and then a commercially available blackening agent (Emplate M
B-438A / Emplate MB-438B / Meltex Co., Ltd.) at 80 ° C. for 5 minutes.
After washing with water and drying, a blackening treatment was performed on the brass insert part. This insert part is set in the mold for injection molding,
Using a polyphenylene sulfide resin containing 30% by weight of glass fiber and 30% by weight of calcium carbonate, injection molding was performed under the molding conditions shown in Table 1 to obtain a sample for evaluation having the shape shown in FIG. The test was performed. Table 3 shows the results.

Example 2 A polybutylene terephthalate resin containing 15% by weight of glass fiber and 15% by weight of glass flake was used as a molding resin, and injection molding was performed under the molding conditions shown in Table 2. A sample for evaluation was prepared in the same manner as in Example 1,
The above airtightness test was performed. Table 3 shows the results.

Comparative Example 1 A sample for evaluation was prepared in the same manner as in Example 1, except that the insert part made of brass was not subjected to the blackening treatment, and the above airtightness test was performed. Table 3 shows the results.

Comparative Example 2 An evaluation sample was prepared in the same manner as in Example 2 except that the brass insert part was not subjected to the blackening treatment, and the above airtightness test was performed. Table 3 shows the results.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

[0017]

As is apparent from the above description and Examples, the metal insert resin molded product obtained by the method of the present invention has extremely high airtightness at the resin / metal interface and is exposed to a severe environment. Can maintain its excellent airtightness, so that a highly reliable product can be provided for a long period of time. Therefore, the resin molded article produced by the production method of the present invention is suitable for metal insert resin parts in a wide range of fields, including various sensor parts for automobiles, various switch parts for home appliances, capacitor parts for various industrial equipment, and the like. It can be used for

[Brief description of the drawings]

FIG. 1 is a view showing the shape of an insert metal part used in Examples, (a) is a top view, and (b) is a front view.

FIG. 2 is a view showing the shape of a resin molded product obtained by injection-molding a thermoplastic resin material into an insert metal part used in Examples, (a) is a top view, and (b) is a perspective view. It is.

FIG. 3 is a schematic view of a test device in an airtightness evaluation performed in an example, (a) is an overall view, and (b) is an enlarged sectional view of a pressure-resistant airtight container.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) B29K 67:00 77:00 81:00 B29L 31:34

Claims (5)

[Claims] 1. A method for producing a resin molded product in which a metal part made of copper or a copper alloy is inserted, wherein a black oxide film is previously formed on all or part of the surface of the metal part made of copper or a copper alloy. Then, the metal part is inserted into a mold of an injection molding machine and injection molded using a thermoplastic resin material. 2. A thermoplastic resin material comprising a polyacetal resin, a polyethylene terephthalate resin, a polybutylene terephthalate resin, a polyphenylene sulfide resin,
2. The metal according to claim 1, wherein at least one resin selected from the group consisting of a polyamide resin, a liquid crystalline polyester resin, a polyimide resin, a syndiotactic polystyrene resin, and a polycyclohexane dimethylene terephthalate resin is used as a main component. Manufacturing method of insert resin molded product. 3. A resin molded product substantially forming a part of an electric circuit device, produced by the production method according to claim 1. 4. The resin molded product according to claim 3, wherein the metal component made of copper or a copper alloy has a function substantially as an electric connection terminal. 5. The resin molded product according to claim 3, which is a component of any one of a sensor, a switch, and a capacitor.